CAPACITY-COMPENSATION ELECTROLYTE ADDITIVE, PREPARATION METHOD AND APPLICATION, ELECTROLYTE CONTAINING THE SAME, AND SECONDARY BATTERY
20230223597 · 2023-07-13
Inventors
Cpc classification
Y02E60/10
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
H01M10/0525
ELECTRICITY
International classification
H01M10/0525
ELECTRICITY
H01M10/054
ELECTRICITY
Abstract
The present disclosure discloses a capacity-compensation electrolyte additive and electrolyte having the same, the additive comprises one or more of Li.sub.xP.sub.y, Na.sub.mP.sub.n and K.sub.pP.sub.q, where 0<x≤3, 0<y≤11, 0<m≤3, 0<n≤11, 0<p≤3 and 0<q≤11, the electrolyte is applied to a lithium-ion battery, a sodium-ion battery or a potassium-ion battery. The additive can decompose active ions and electrons during whole charge-discharge cycle, and improves the initial Coulombic efficiency of the battery, specific capacity and cycling stability, so as to achieve uniform capacity compensation; and the additive is dissolved prior to electrolyte solvents, the products stabilize both of cathode and anode solid electrolyte layer, and improve capacity retention ratio in batteries so as to achieve stable cycling. Adding additive in electrolyte will not hazard electrode structure, can achieve uniform capacity compensation, has higher safety and easy to implement.
Claims
1. A capacity-compensation electrolyte additive, comprising one or more of Li.sub.xP.sub.y, Na.sub.mP.sub.n and K.sub.pP.sub.q, where 0<x≤3, 0<y≤11, 0<m≤3, 0<n≤11, 0<p≤3 and 0<q≤11.
2. The electrolyte additive according to claim 1, wherein the additive comprises one or more of the Li.sub.xP.sub.y, the Na.sub.mP.sub.n and the K.sub.pP.sub.q, where 1≤x<3, 4≤y≤10, 1≤m<3, 4≤n≤10, 1≤p≤3 and 4≤q≤10.
3. The electrolyte additive according to claim 1, wherein preferably, the Li.sub.xP.sub.y is selected from one or more of LiP.sub.4, LiP.sub.8, LiP.sub.7, LiP.sub.8 and LiP.sub.10; preferably, the Na.sub.mP.sub.n is selected from one or more of NaP.sub.4, NaP.sub.5, NaP.sub.7 and NaP.sub.10; and preferably, the K.sub.pP.sub.q is selected from one or more of KP.sub.4, KP.sub.5, KP.sub.7 and K.sub.3P.sub.7.
4. The electrolyte additive according to claim 1, wherein the additive is dissolved in an electrolyte, and the electrolyte is applied to a secondary battery; and preferably, the secondary battery comprises a lithium-ion battery, a sodium-ion battery or a potassium-ion battery.
5. A preparation method of the capacity-compensation electrolyte additive according to claim 1, wherein the preparation method comprises: adding red phosphorus to a Li-biphenyl solution, a Na-biphenyl solution or a K-biphenyl solution respectively, and stirring the solution at a certain temperature to obtain a Li.sub.xP.sub.y solid, a Na.sub.mP.sub.n solid or a K.sub.pP.sub.q solid, where 0<x≤3, 0<y≤11, 0<m≤3, 0<n≤11, 0<p≤3 and 0<q≤11.
6. An application of the additive according to claim 1 in the field of electrolyte preparation.
7. The application according to claim 6, wherein the application comprises: soaking and dissolving one or more of the Li.sub.xP.sub.y, the Na.sub.mP.sub.n and the K.sub.pP.sub.q in an electrolyte solvent to obtain the electrolyte containing the additive, where 0<x≤3, 0<y≤11, 0<m≤3, 0<n≤11, 0<p≤3 and 0<q≤11.
8. An electrolyte for a secondary battery, wherein the electrolyte comprises an electrolyte salt, an organic solvent and the capacity-compensation electrolyte additive according to claim 1.
9. The electrolyte according to claim 8, wherein the organic solvent comprises one or more of an ester solvent, an ether solvent, a sulfone solvent and a nitrile solvent; preferably, the ester solvent is selected from one or more of ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene carbonate, chlorocarbonate, ethyl propionate and propyl propionate; preferably, the ether solvent is selected from one or more of dimethoxyethane, 1,3-dioxolane and diglyme; preferably, the sulfone solvent is selected from one or more of sulfolane and dimethyl sulfoxide; and preferably, the nitrile solvent is selected from one or more of succinonitrile and hexanedinitrile.
10. The electrolyte according to claim 8, wherein the mass of the electrolyte additive accounts for 0.1%-25% of the total mass of the electrolyte.
11. A secondary ion battery, comprising a cathode, an anode, a separator and the electrolyte according to claim 8.
12. The secondary ion battery according to claim 11, wherein the secondary battery comprises a lithium-ion battery, a sodium-ion battery or a potassium-ion battery; preferably, the cathode of the lithium-ion battery is selected from one or more of LiCoO.sub.2, LiNiO.sub.2, LiMn.sub.2O.sub.4, LiNi.sub.0.5Mn.sub.1.5O.sub.4, Li.sub.3V.sub.2(PO.sub.4).sub.3, LiFePO.sub.4, LiNi.sub.aCo.sub.bMn.sub.1-a-bO.sub.2, LiNi.sub.cCo.sub.dAl.sub.1-c-dO.sub.2 and S, where 0<a<1, 0<b<1, 0<c<1, and 0<d<1; preferably, the cathode of the sodium-ion battery is selected from one or more of sodium cobaltate, sodium manganate, sodium nickelate, sodium vanadate, sodium manganese phosphate, sodium iron phosphate, sodium vanadium phosphate, nickel-iron sodium manganate and sodium-rich sodium manganate; and preferably, the cathode of the potassium-ion battery is selected from one or more of a Prussian blue analogue containing potassium, KMO.sub.2, K.sub.3V.sub.2(PO.sub.4).sub.2F.sub.3, KVOPO.sub.4, KVPO.sub.4F, K.sub.1-eVP.sub.2O.sub.7, K.sub.4Fe.sub.3(PO.sub.4).sub.2(P.sub.2O.sub.7) and KFeC.sub.2O.sub.4, where M in the KMO.sub.2 is a transition metal, and 0<e<1.
13. The secondary ion battery according to claim 11, wherein the anode is selected from one or more of artificial graphite, natural graphite, a carbon-based anode, a carbon nanotube, silicon and alloys thereof, tin and alloys thereof, germanium and alloys thereof, a phosphorus-based anode, a lithium metal, Li.sub.4Ti.sub.5O.sub.12 and a transition metal compound M.sub.iX.sub.k, where M is a metal element, X is selected from O, S, F or N, 0<i<3, and 0<k<4.
14. Application of a capacity-compensation electrolyte additive, comprising one or more of Li.sub.xP.sub.y, Na.sub.mP.sub.n and K.sub.pP.sub.q, where 0<x≤3, 0<y≤11, 0<m≤3, 0<n≤11, 0<p≤3 and 0<q≤11, an electrolyte for a secondary battery, wherein the electrolyte comprises an electrolyte salt, an organic solvent and the capacity-compensation electrolyte additive, and a secondary ion battery, comprising a cathode, an anode, a separator and the electrolyte.
15. The method of claim 5, wherein the additive comprises one or more of the Li.sub.xP.sub.y, the Na.sub.mP.sub.n and the K.sub.pP.sub.q, where 1≤x<3, 4≤y≤10, 1≤m<3, 4≤n≤10, 1≤p≤3 and 4≤q≤10.
16. The method of claim 5, wherein the additive comprises one or more of the Li.sub.xP.sub.y, the Na.sub.mP.sub.n and the K.sub.pP.sub.q, where 1≤x<3, 4≤y≤10, 1≤m<3, 4≤n≤10, 1≤p≤3 and 4≤q≤10.
17. The method of claim 5, wherein preferably, the Li.sub.xP.sub.y is selected from one or more of LiP.sub.4, LiP.sub.8, LiP.sub.7, LiP.sub.8 and LiP.sub.10; preferably, the Na.sub.mP.sub.n is selected from one or more of NaP.sub.4, NaP.sub.5, NaP.sub.7 and NaP.sub.10; and preferably, the K.sub.pP.sub.q is selected from one or more of KP.sub.4, KP.sub.5, KP.sub.7 and K.sub.3P.sub.7.
18. The method of claim 5, wherein the additive is dissolved in an electrolyte, and the electrolyte is applied to a secondary battery; and preferably, the secondary battery comprises a lithium-ion battery, a sodium-ion battery or a potassium-ion battery.
19. The application of claim 6, wherein the additive comprises one or more of the Li.sub.xP.sub.y, the Na.sub.mP.sub.n and the K.sub.pP.sub.q, where 1≤x<3, 4≤y≤10, 1≤m<3, 4≤n≤10, 1≤p≤3 and 4≤q≤10.
20. The application of claim 6, wherein preferably, the Li.sub.xP.sub.y is selected from one or more of LiP.sub.4, LiP.sub.8, LiP.sub.7, LiP.sub.8 and LiP.sub.10; preferably, the Na.sub.mP.sub.n is selected from one or more of NaP.sub.4, NaP.sub.5, NaP.sub.7 and NaP.sub.10; and preferably, the K.sub.pP.sub.q is selected from one or more of KP.sub.4, KP.sub.5, KP.sub.7 and K.sub.3P.sub.7.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0233]
[0234]
[0235]
[0236]
[0237]
DETAILED DESCRIPTION OF THE PRESENT DISCLOSURE
[0238] Specific implementations of the present disclosure will be described below. Apparently, the described embodiments are only a part of embodiments of the present disclosure rather than all embodiments. All other embodiments obtained by those ordinarily skilled in the art without involving inventive effort based on the embodiments in the present disclosure fall within the protection scope of the present disclosure.
[0239] The present application provides a capacity-compensation electrolyte additive, including one or a combination of more of Li.sub.xP.sub.y, Na.sub.mP.sub.n and K.sub.pP.sub.q, where 0<x≤3, 0<y≤11, 0<m≤3, 0<n≤11, 0<p≤3, and 0<q≤11. The additive may be dissolved in an electrolyte and applied to a secondary battery. The additive may decompose prior to an electrolyte solvent and an electrolyte salt to release the active ions for compensating the capacity loss occurred in the first cycle and subsequent cycle processes of the battery, and therefore the cycle stability and energy density of the batter are improved.
[0240] According to some implementations of the present application, the secondary battery includes a lithium-ion battery, a sodium-ion battery or a potassium-ion battery.
[0241] According to some implementations of the present application, in the lithium-ion battery, the additive is preferably Li.sub.xP.sub.y, and preferably, 1≤x<3, and 4≤y≤10; and the Li.sub.xP.sub.y is preferably LiP.sub.4, LiP.sub.5, LiP.sub.7, LiP.sub.8 or LiP.sub.10, and most preferably, LiP.sub.5 or LiP.sub.7;
[0242] According to some implementations of the present application, in the sodium-ion battery, the additive is preferably Na.sub.mP.sub.n, and preferably, 1≤m<3, and 4≤n≤10; and the Na.sub.mP.sub.n is preferably NaP.sub.4, NaP.sub.5, NaP.sub.7 or NaP.sub.10, and most preferably, NaP.sub.5 or NaP.sub.7; and
[0243] According to some implementations of the present application, in the potassium-ion battery, the additive is preferably K.sub.pP.sub.q, and preferably, 1≤p≤3, and 4≤q≤10; and the K.sub.pP.sub.q is preferably KP.sub.4, KP.sub.5, KP.sub.7 or K.sub.3P.sub.7, and most preferably, KP.sub.5 or K.sub.3P.sub.7.
[0244] Electrolyte lithium compensating additives in the prior art have the defects of poor compatibility with the electrolyte solvents. Researches on lithium polyphosphide mostly remain in these common lithium polyphosphide compounds such as Li.sub.3P and Li.sub.5P, which are mostly used to compensate lithium in electrodes or to modify lithium metal surfaces. The applicant of the present disclosure tried to add these substances to the electrolyte, and it was verified by a large number of experiments that these conventional lithium polyphosphate solids show poor solubility in widely used electrolyte solvents, and are unsuitable for serving as electrolyte lithium-compensating additives.
[0245] After long-term creative work, the applicant of the present disclosure developed a new polyphosphide preparation method. By this method, LiP.sub.4, LiP.sub.5, LiP.sub.7, LiP.sub.8 and LiP.sub.10, especially LiP.sub.5 and LiP.sub.7 could be prepared, and it was verified by a large number of experiments that these lithium polyphosphates could be dissolved in common ester, ether, sulfone or nitrile organic solvents which could serve as the electrolyte solvents. Meanwhile, the applicant also found that when these lithium polyphosphates which could be dissolved in the electrolyte solvents were added to the electrolyte, the lithium polyphosphates could decompose prior to the electrolyte solvents on the surface of an electrode, achieving an excellent effect of compensating lithium and electrons. Therefore, capacity loss caused by formation of the SEI in a battery cycling process and generation of dead lithium in the subsequent cycling process could be compensated.
[0246] In a sodium-ion battery, the applicant of the present disclosure developed sodium polyphosphates (such as NaP.sub.4, NaP.sub.5, NaP.sub.7 and NaP.sub.10) which could be dissolved in the electrolyte solvents, and added to the electrolyte as the additive, and the sodium polyphosphates could also decompose prior to the solvents in the electrolyte, achieving the effect of compensating the sodium and the electrons. Therefore, capacity loss caused by formation of the SEI in the battery cycling process and generation of dead sodium in the subsequent cycling process could be compensated.
[0247] In a potassium-ion battery, the applicant of the present disclosure developed potassium polyphosphates (such as KP.sub.4, KP.sub.5, KP.sub.7 and K.sub.3P.sub.7) which could be dissolved in the electrolyte solvents, and added them to the electrolyte as the additive, and the potassium polyphosphates could also decompose prior to the solvents in the electrolyte, achieving the effect of compensating the potassium and the electrons. Therefore, capacity loss caused by formation of the SEI in the battery cycling process and generation of dead potassium in the subsequent cycling process could be compensated. These achievements and technical solutions are discovered and reported by the applicant for the first time.
[0248] The above additives are higher in solubility in the common electrolyte solvents, and have a lower LUMO energy level and a higher HOMO energy level. The additive is decomposed on an anode side prior to the electrolyte solvents due to the LUMO energy level lower than that of the electrolyte solvents, so that stable SEI is preferentially formed on the surface of the anode. The additive is decomposed on a cathode side prior to the electrolyte solvents due to the HOMO energy level higher than that of the electrolyte solvents, so that stable CEI is preferentially formed on the surface of the cathode. Thus, the additive can improve the stability of an electrode-electrolyte interface in the battery and improve the cycle property of the battery.
[0249] The present application further provides a preparation method of the above-mentioned electrolyte additive. The additive includes one or more of the Li.sub.xP.sub.y, the Na.sub.mP.sub.n and the K.sub.pP.sub.q, and the method includes the step that a certain amount of red phosphorus is added to a Li-biphenyl solution, a Na-biphenyl solution or a K-biphenyl solution, and stirred at a certain temperature to obtain a Li.sub.xP.sub.y solid, a Na.sub.mP.sub.n solid or a K.sub.pP.sub.q solid by centrifuging and evaporating the solvent to dryness.
[0250] In the prior art, there was no report on preparation of the Li.sub.xP.sub.y, Na.sub.mP.sub.n and K.sub.pP.sub.q solids by adopting the above method. The applicant firstly adopted mild liquid-solid reactions, namely reactions between Li-biphenyl and red phosphorus, between Na-biphenyl and red phosphorus, and between K-biphenyl and red phosphorus, to prepare the Li.sub.xP.sub.y, Na.sub.mP.sub.n and K.sub.pP.sub.q solids respectively. In this method, different lithium, sodium, potassium and phosphorus compounds could be prepared by regulating the proportions of the Li-biphenyl, the Na-biphenyl and the K-biphenyl to the red phosphorus, and high-temperature heating can be avoided. The prepared phosphorus-containing compound was soaked in the electrolyte, and soluble components could be dissolved in the electrolyte as capacity compensation additives, which played a role in compensating active ions and electrons.
[0251] The present application further provides application of a phosphorus-containing substance as an electrolyte additive. The phosphorus-containing substance includes one or a combination of more of Li.sub.xP.sub.y, Na.sub.mP.sub.n and K.sub.pP.sub.q, and the phosphorus-containing substance is dissolved in the electrolyte;
[0252] Where, 0<x≤3, 0<y≤11, 0<m≤3, 0<n≤11, 0<p≤3 and 0<q≤11.
[0253] The application of the present disclosure includes the step that one or more of the Li.sub.xP.sub.y, the Na.sub.mP.sub.n and the K.sub.pP.sub.q is soaked in the electrolyte solvent for dissolving to obtain the electrolyte containing the additive. In order to solve the problems of damage of lithium supplement in an electrode to an electrode plate structure and low compatibility of some existing electrolyte lithium-compensating additives in the electrolyte solvent, the applicant firstly proposed that soluble polyphosphides were dissolved in the electrolyte as lithium/sodium/potassium-compensating additives, and the additives could be compatible with common electrolyte solvents, electrolyte salts and cathode/anode systems, which can not only play a role in releasing the active ions through decomposition, but can also stabilize the electrode interface and improve the cycle stability of the battery. The effects of the polyphosphides will be further validated in embodiments in combination with test data.
[0254] According to some implementations of the present application, the phosphorus-containing substance includes the Li.sub.xP.sub.y; and the application of the Li.sub.xP.sub.y serving as the additive includes:
[0255] red phosphorus is added to a Li-biphenyl solution, and stirred at a certain temperature to obtain a Li.sub.xP.sub.y solid by centrifuging and evaporating the solvent to dryness; and an electrolyte salt is added to the electrolyte solvent for dissolving, and then the Li.sub.xP.sub.y solid is soaked in the electrolyte solvent for dissolving to obtain the electrolyte with the Li.sub.xP.sub.y dissolved. Wherein, the optional solvent of the Li-biphenyl solution is one or more of the tetrahydrofuran, the dimethoxyethane, the tetraethylene glycol dimethyl ether and the diglyme.
[0256] According to some implementations of the present application, the additive is added to the electrolyte in the inert gas atmosphere, such as the argon atmosphere. It is the same as common liquid injection environment, and additional steps are not required in industrial production.
[0257] According to some implementations of the present application, the solvent of the Li-biphenyl solution is selected from the tetrahydrofuran and the dimethoxyethane. As the boiling points of the two solvents are lower, the solvents are easy to evaporate after synthesis to obtain the pure Li.sub.xP.sub.y.
[0258] According to some implementations of the present application, the concentration of the Li-biphenyl solution is 0.2 mol/L to 2.0 mol/L. The concentration of the Li-biphenyl solution is preferably 0.8 mol/L to 1.2 mol/L, and the concentration of the Li-biphenyl solution is most preferably, 1.0 mol/L to 1.1 mol/L. In the preferred concentration of the Li-biphenyl solution, the yield of the obtained lithium polyphosphates is higher.
[0259] According to some implementations of the present application, the molar ratio of the amount of the red phosphorus added to the Li-biphenyl solution to Li is 1:5 to 11:1, preferably 1:3 to 5:1, and most preferably, 1:3 to 7:3. In the preferred range, the soluble product of the obtained lithium polyphosphates in the electrolyte is higher in solubility, and can achieve a better effect of capacity compensation.
[0260] According to some implementations of the present application, the stirring time of the Li-biphenyl solution with the red phosphorus added is 2 hours to 30 hours, preferably 6 hours to 15 hours, and most preferably, 10 hours to 12 hours. In the preferred time range, the red phosphorus and the Li-biphenyl can react fully to obtain an ideal reaction product.
[0261] According to some implementations of the present application, the stirring condition of the Li-biphenyl solution with the red phosphorus added is 25° C. to 40° C., and preferably 25° C. to 35° C. Under the above reaction conditions, the Li-biphenyl can react with the red phosphorus fully to obtain the product Li.sub.xP.sub.y.
[0262] According to some implementations of the present application, the soaking time of the Li.sub.xP.sub.y solid in the electrolyte is 6 hours to 48 hours, preferably 12 hours to 30 hours, and most preferably, 20 hours to 24 hours. Within the preferred soaking time, the Li.sub.xP.sub.y solid can be fully dissolved in the electrolyte solvent to reach a certain amount of addition.
[0263] According to some implementations of the present application, the amount of the Li.sub.xP.sub.y solid soaked in the electrolyte is 0.2 g/L to 10.0 g/L, preferably 1.0 g/L to 5.0 g/L, and most preferably, 1.2 g/L to 3.0 g/L. Under the above reaction conditions, the electrolyte with the Li.sub.xP.sub.y additive dissolved is obtained, and can reach a proper concentration.
[0264] According to some implementations of the present application, the phosphorus-containing substance includes the Na.sub.mP.sub.n; and the application of the Na.sub.mP.sub.n serving as the additive includes:
[0265] adding the red phosphorus to the Na-biphenyl solution, and stirring the solution at a certain temperature to obtain the Na.sub.mP.sub.n solid by centrifuging and evaporating the solvent to dryness; and adding the electrolyte salt to the electrolyte solvent and dissolving the electrolyte salt, and then soaking and dissolving the Na.sub.mP.sub.n solid in the electrolyte solvent to obtain the electrolyte with the Na.sub.mP.sub.n dissolved. Wherein, the optional solvent of the Na-biphenyl solution is one or more of tetrahydrofuran, dimethoxyethane, tetraethylene glycol dimethyl ether and diglyme.
[0266] According to some implementations of the present application, the solvent of the Na-biphenyl solution is selected from the tetrahydrofuran and the dimethoxyethane. As the boiling points of the two solvents are lower, the solvents are easy to evaporate after synthesis to obtain the pure Na.sub.mP.sub.n.
[0267] According to some implementations of the present application, the concentration of the Na-biphenyl solution is 0.2 mol/L to 2.0 mol/L. The concentration of the Na-biphenyl solution is preferably 0.8 mol/L to 1.2 mol/L, and the concentration of the Na-biphenyl solution is most preferably 1.0 mol/L to 1.1 mol/L. In the preferred concentration of the Na-biphenyl solution, the yield of the obtained sodium polyphosphates is higher.
[0268] According to some implementations of the present application, the molar ratio of the amount of the red phosphorus added to the Na-biphenyl solution to Na is 1:5 to 11:1, preferably 1:3 to 5:1, and most preferably, 1:3 to 7:3. In the preferred range, the soluble product of the obtained sodium polyphosphates in the electrolyte is higher in solubility, and can achieve a better effect of capacity compensation.
[0269] According to some implementations of the present application, the stirring time of the Na-biphenyl solution with the red phosphorus added is 2 hours to 30 hours, preferably 6 hours to 15 hours, and most preferably, 10 hours to 12 hours. In the preferred time range, the red phosphorus and the Na-biphenyl can react fully to obtain an ideal reaction product.
[0270] According to some implementations of the present application, the stirring condition of the Na-biphenyl solution with the red phosphorus added is 25° C. to 40° C., and preferably 25° C. to 35° C. Under the above reaction conditions, the Na-biphenyl can react with the red phosphorus fully to obtain the product Na.sub.mP.sub.n.
[0271] According to some implementations of the present application, the soaking time of the Na.sub.mP.sub.n solid in the electrolyte is 6 hours to 48 hours, preferably 12 hours to 30 hours, and most preferably, 20 hours to 24 hours. Within the preferred soaking time, the Na.sub.mP.sub.n solid can be fully dissolved in the electrolyte solvent to reach a certain amount of addition.
[0272] According to some implementations of the present application, the amount of the Na.sub.mP.sub.n solid soaked in the electrolyte is 0.2 g/L to 10.0 g/L, preferably 1.0 g/L to 5.0 g/L, and most preferably, 1.2 g/L to 3.0 g/L. Under the above reaction conditions, the electrolyte with the Na.sub.mP.sub.n additive dissolved is obtained, and can reach a proper concentration.
[0273] According to some implementations of the present application, the phosphorus-containing substance includes the K.sub.pP.sub.q; and the application of the K.sub.pP.sub.q serving as the additive includes:
[0274] adding the red phosphorus to the K-biphenyl solution, and stirring the solution at a certain temperature to obtain the K.sub.pP.sub.q solid by centrifuging and evaporating the solvent to dryness; and adding the electrolyte salt to the electrolyte solvent and dissolving the electrolyte salt, and then soaking and dissolving the K.sub.pP.sub.q solid in the electrolyte solvent to obtain the electrolyte with the K.sub.pP.sub.q dissolved. Wherein, the optional solvent of K-biphenyl solution is one or more of the tetrahydrofuran, the dimethoxyethane, the tetraethylene glycol dimethyl ether and the diglyme.
[0275] According to some implementations of the present application, the solvent of K-biphenyl solution is selected from the tetrahydrofuran and the dimethoxyethane. As the boiling points of the two solvents are lower, the solvents are easy to evaporate after synthesis to obtain the pure K.sub.pP.sub.q.
[0276] According to some implementations of the present application, the concentration of the K-biphenyl solution is 0.2 mol/L to 2.0 mol/L. The concentration of the K-biphenyl solution is preferably 0.8 mol/L to 1.2 mol/L, and the concentration of the K-biphenyl solution is most preferably 1.0 mol/L to 1.1 mol/L. In the preferred concentration of the K-biphenyl solution, the yield of the obtained potassium polyphosphates is higher.
[0277] According to some implementations of the present application, the molar ratio of the amount of the red phosphorus added to the K-biphenyl solution to K is 1:5 to 11:1, preferably 1:3 to 5:1, and most preferably, 1:3 to 7:3. In the preferred range, the soluble product of the obtained potassium polyphosphates in the electrolyte is higher in solubility, and can achieve a better effect of capacity compensation.
[0278] According to some implementations of the present application, the stirring time of the K-biphenyl solution with the red phosphorus added is 2 hours to 30 hours, preferably 6 hours to 15 hours, and most preferably, 10 hours to 12 hours. In the preferred time range, the red phosphorus and K-biphenyl can react fully to obtain the ideal reaction product.
[0279] According to some implementations of the present application, the stirring condition of the K-biphenyl solution with the red phosphorus added is 25° C. to 40° C., and preferably 25° C. to 35° C. Under the above reaction conditions, the K-biphenyl can react with the red phosphorus fully to obtain the product K.sub.pP.sub.q.
[0280] According to some implementations of the present application, the soaking time of the K.sub.pP.sub.q solid in the electrolyte is 6 hours to 48 hours, preferably 12 hours to 30 hours, and most preferably, 20 hours to 24 hours. Within the preferred soaking time, the K.sub.pP.sub.q solid can be fully dissolved in the electrolyte solvent to reach a certain amount of addition.
[0281] According to some implementations of the present application, the amount of the K.sub.pP.sub.q solid soaked in the electrolyte is 0.2 g/L to 10.0 g/L, preferably 1.0 g/L to 5.0 g/L, and most preferably, 1.2 g/L to 3.0 g/L. Under the above reaction conditions, the electrolyte with the K.sub.pP.sub.q additive dissolved is obtained, and can reach a proper concentration.
[0282] The present application further discloses a preparation method of a phosphide. The phosphide is Li.sub.xP.sub.y, where 0<x≤3 and 0<y≤11, and the specific preparation method includes the step that red phosphorus is added to a Li-biphenyl solution, and stirred at a certain temperature to obtain a Li.sub.xP.sub.y solid by centrifuging and evaporating the solvent to dryness. Wherein, the optional solvent of the Li-biphenyl solution is one or more of the tetrahydrofuran, the dimethoxyethane, the tetraethylene glycol dimethyl ether and the diglyme.
[0283] In the liquid-solid reaction preparation method, specific Li.sub.xP.sub.y products can be obtained by regulating a Li—P ratio. When these products are soaked in the electrolyte, soluble components (such as LiP.sub.4, LiP.sub.5, LiP.sub.7, LiP.sub.8 and LiP.sub.10) with higher compatibility with the electrolyte solvent may be dissolved, and thus such products are more suitable to serve as electrolyte capacity compensation additives.
[0284] According to some implementations of the present application, the solvent of the Li-biphenyl solution is selected from the tetrahydrofuran and the dimethoxyethane. As the boiling points of the two solvents are lower, the solvents are easy to evaporate after synthesis to obtain the pure Li.sub.xP.sub.y.
[0285] According to some implementations of the present application, the concentration of the Li-biphenyl solution is 0.2 mol/L to 2.0 mol/L. The concentration of the Li-biphenyl solution is preferably 0.8 mol/L to 1.2 mol/L, and the concentration of the Li-biphenyl solution is most preferably, 1.0 mol/L to 1.1 mol/L. In the preferred concentration of the Li-biphenyl solution, the yield of the obtained lithium polyphosphates is higher.
[0286] According to some implementations of the present application, the molar ratio of the amount of the red phosphorus added to the Li-biphenyl solution to Li is 1:5 to 11:1, preferably 1:3 to 5:1, and most preferably, 1:3 to 7:3. In the preferred range, the soluble product of the obtained lithium polyphosphates in the electrolyte is higher in solubility, and can achieve a better effect of capacity compensation.
[0287] According to some implementations of the present application, the stirring time of the Li-biphenyl solution with the red phosphorus added is 2 hours to 30 hours, preferably 6 hours to 15 hours, and most preferably, 10 hours to 12 hours. In the preferred time range, the red phosphorus and the Li-biphenyl can react fully to obtain an ideal reaction product.
[0288] According to some implementations of the present application, the stirring condition of the Li-biphenyl solution with the red phosphorus added is 25° C. to 40° C., and preferably 25° C. to 35° C. Under the above reaction conditions, the Li-biphenyl can react with the red phosphorus fully to obtain the pure Li.sub.xP.sub.y.
[0289] The present application further discloses a preparation method of a phosphide Na.sub.mP.sub.n, where 0<m≤3 and 0<n≤11, and the specific preparation method includes the step: red phosphorus is added to a Na-biphenyl solution, and stirred at a certain temperature to obtain a Na.sub.mP.sub.n solid by centrifuging and evaporating the solvent to dryness. Wherein, the optional solvent of the Na-biphenyl solution is one or more of the tetrahydrofuran, the dimethoxyethane, the tetraethylene glycol dimethyl ether and the diglyme.
[0290] In the liquid-solid reaction preparation method, specific Na.sub.mP.sub.n products can be obtained by regulating a Na—P ratio. When these products are soaked in the electrolyte, soluble components (such as NaP.sub.4, NaP.sub.5, NaP.sub.7 and NaP.sub.10) with higher compatibility with the electrolyte solvent may be dissolved, and thus, such products are more suitable to serve as electrolyte capacity compensation additives.
[0291] According to some implementations of the present application, the solvent of the Na-biphenyl solution is selected from the tetrahydrofuran and the dimethoxyethane. As the boiling points of the two solvents are lower, the solvents are easy to evaporate after synthesis to obtain the pure Na.sub.mP.sub.n.
[0292] According to some implementations of the present application, the concentration of the Na-biphenyl solution is 0.2 mol/L to 2.0 mol/L. The concentration of the Na-biphenyl solution is preferably 0.8 mol/L to 1.2 mol/L, and the concentration of the Na-biphenyl solution is most preferably 1.0 mol/L to 1.1 mol/L. In the preferred concentration of the Na-biphenyl solution, the yield of the obtained sodium polyphosphates is higher.
[0293] According to some implementations of the present application, the molar ratio of the amount of the red phosphorus added to the Na-biphenyl solution to Na is 1:5 to 11:1, preferably 1:3 to 5:1, and most preferably, 1:3 to 7:3. In the preferred range, the soluble product of the obtained sodium polyphosphates in the electrolyte is higher in solubility, and can achieve a better effect of capacity compensation.
[0294] According to some implementations of the present application, the stirring time of the Na-biphenyl solution with the red phosphorus added is 2 hours to 30 hours, preferably 6 hours to 15 hours, and most preferably, 10 hours to 12 hours. In the preferred time range, the red phosphorus and the Na-biphenyl can react fully to obtain an ideal reaction product.
[0295] According to some implementations of the present application, the stirring condition of the Na-biphenyl solution with the red phosphorus added is 25° C. to 40° C., and preferably 25° C. to 35° C. Under each reaction condition, the Na-biphenyl can react with the red phosphorus fully to obtain the pure Na.sub.mP.sub.n.
[0296] The present application further discloses a preparation method of a phosphide K.sub.pP.sub.q, where 0<p≤3 and 0<q≤11, and the specific preparation method includes the step: red phosphorus is added to a K-biphenyl solution, and stirred at a certain temperature to obtain a K.sub.pP.sub.q solid by centrifuging and evaporating the solvent to dryness. Wherein, the optional solvent of K-biphenyl solution is one or more of the tetrahydrofuran, the dimethoxyethane, the tetraethyleneglycol dimethyl ether and the diglyme.
[0297] In the liquid-solid reaction preparation method, specific K.sub.pP.sub.q products can be obtained by regulating a K—P ratio. When these products are soaked in the electrolyte, soluble components (such as KP.sub.4, KP.sub.5, KP.sub.7 and K.sub.3P.sub.7) with higher compatibility with the electrolyte solvent will be dissolved, and thus, such products are more suitable to serve as an electrolyte capacity-compensation additive.
[0298] According to some implementations of the present application, the solvent of K-biphenyl solution is selected from the tetrahydrofuran and the dimethoxyethane. As the boiling points of the two solvents are lower, the solvents are easy to evaporate after synthesis to obtain the pure K.sub.pP.sub.q.
[0299] According to some implementations of the present application, the concentration of the K-biphenyl solution is 0.2 mol/L to 2.0 mol/L. The concentration of the K-biphenyl solution is preferably 0.8 mol/L to 1.2 mol/L, and the concentration of the K-biphenyl solution is most preferably, 1.0 mol/L to 1.1 mol/L. In the preferred concentration of the K-biphenyl solution, the yield of the obtained potassium polyphosphates is higher.
[0300] According to some implementations of the present application, the molar ratio of the amount of the red phosphorus added to the K-biphenyl solution to K is 1:5 to 11:1, preferably 1:3 to 5:1, and most preferably, 1:3 to 7:3. In the preferred range, the soluble product of the obtained potassium polyphosphates in the electrolyte is higher in solubility, and can achieve a better effect of capacity compensation.
[0301] According to some implementations of the present application, the stirring time of the K-biphenyl solution with the red phosphorus added is 2 hours to 30 hours, preferably 6 hours to 15 hours, and most preferably, 10 hours to 12 hours. In the preferred time range, the red phosphorus and K-biphenyl can react fully to obtain the ideal reaction product.
[0302] According to some implementations of the present application, the stirring condition of the K-biphenyl solution with the red phosphorus added is 25° C. to 40° C., and preferably 25° C. to 35° C. Under the above reaction conditions, the K-biphenyl can react with the red phosphorus fully to obtain the pure K.sub.pP.sub.q.
[0303] The present application further discloses an electrolyte for a secondary battery, and the electrolyte includes an electrolyte salt, an organic solvent and the above-mentioned capacity-compensation electrolyte additives. In the working process of the electrolyte, the additive may decompose prior to an electrolyte solvent and an electrolyte salt to release the active ions for compensating the capacity loss occurred in the first cycle and subsequent cycle processes of the battery, and therefore the cycle stability and energy density of the batter are improved.
[0304] According to some implementations of the present application, the organic solvent includes one or more of an ester solvent, an ether solvent, a sulfone solvent and a nitrile solvent. The phosphorus-containing substance includes Li.sub.xP.sub.y, Na.sub.mP.sub.n and K.sub.pP.sub.q, which are higher in compatibility with the above solvents and may reach a certain solubility.
[0305] In the electrolyte during the working process of the battery, by taking LiP.sub.7 as an example, the following reaction can occur:
LiP.sub.7.fwdarw.Li.sup.+P.sub.7.sup.−
[0306] After extensive testing validation, the applicant found that the Li.sub.xP.sub.y, the Na.sub.mP.sub.n and the K.sub.pP.sub.q were higher in compatibility with common electrolytes, and extremely wide in practicability, wherein the organic solvent may be one or mixtures of more of the ester solvent, the ether solvent, the sulfone solvent and the nitrile solvent, and the proportion of the solvents may not be specifically limited, such as EC:DEC=1:1.
[0307] According to some implementations of the present application, the ester solvent is selected from one or more of ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), propylene carbonate (PC), chlorocarbonate (Cl MC), ethyl propionate (EP) and propyl propionate (PP);
[0308] According to some implementations of the present application, the ether solvent is selected from one or more of dimethoxyethane (DME), 1,3-dioxolame (1,3-DOL) and diglyme (DG);
[0309] According to some implementations of the present application, the sulfone solvent is selected from one or more of sulfolane (SL) and dimethyl sulfoxide (DMSO); and
[0310] According to some implementations of the present application, the nitrile solvent is selected from one or more of acetonitrile (AN), succinonitrile (SN) and hexanedinitrile (HN). The phosphorus-containing substance includes Li.sub.xP.sub.y, Na.sub.mP.sub.n and K.sub.pP.sub.q, which are higher in compatibility with the above additives and can reach a certain solubility, to achieve the effect of the electrolyte additives.
[0311] According to some implementations of the present application, in the electrolyte salt, the electrolyte for the lithium-ion battery includes one or a combination of more of lithium hexafluorophosphate (LiPF.sub.6), lithium tetrafluoroborate (LiBF.sub.4), lithium perchlorate (LiClO.sub.4), lithium hexafluoroarsenate (LiAsF.sub.6), lithium bis(oxalate)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiCF.sub.3SO.sub.3), lithium bis(trifluoromethylsulfonyl)imide (LiN(CF.sub.3SO.sub.2).sub.2) and lithium tetrafluorooxalate phosphate (LiPF.sub.4(C.sub.2O.sub.4)). According to some implementations of the present application, in the electrolyte salt, the electrolyte for the lithium-ion battery is selected from LiPF.sub.6, LiBF.sub.4, LiBOB, LiDFOB, LiFSI and LiTFSI. The above lithium salts do not react with the lithium polyphosphate chemically, and are higher in compatibility.
[0312] According to some implementations of the present application, the electrolyte salt for the sodium-ion battery includes NaClO.sub.4 and/or NaPF.sub.6. The above sodium salts do not react with the sodium polyphosphate chemically, and are higher in compatibility.
[0313] The electrolyte salt for the potassium-ion battery includes one or more of potassium hexafluorophosphate (KPF.sub.6), potassium bis(trifluoromethanesulfonly)imide (KTFSI) and potassium bis(fluorosulfonyl)imide (KFSI). The above electrolyte salts can be dissolved in the electrolyte properly, do not react with the potassium polyphosphate chemically, and are higher in compatibility.
[0314] According to some implementations of the present application, the mass percentage of the electrolyte additive dissolved in the electrolyte is 0.1% to 25%.
[0315] According to some implementations of the present application, the mass percentage of the electrolyte additive dissolved in the electrolyte is 8% to 12%.
[0316] According to some implementations of the present application, the mass percentage of the electrolyte additive dissolved in the electrolyte is most preferably 10%. Too few additives may result in insufficient compensation for capacity losses caused by volume expansion and pulverization of electrodes in the cycle process, while introduction of too many additives may result in excessive additive mass, leading to reduction in whole energy density of the battery.
[0317] The present application further discloses a preparation method of the electrolyte for the secondary battery, the electrolyte includes an electrolyte salt, an organic solvent and an electrolyte additive Li.sub.xP.sub.y, Na.sub.mP.sub.n or K.sub.pP.sub.q, where 0<x≤3, 0<y≤11, 0<m≤3, 0<n≤11, 0<p≤3, and 0<q≤11, and the preparation method of the electrolyte includes:
[0318] red phosphorus is added to a Li-biphenyl solution, and stirred at a certain temperature to obtain a Li.sub.xP.sub.y solid, a Na.sub.mP.sub.n solid or a K.sub.pP.sub.q solid; and the electrolyte salt is added to the electrolyte solvent for dissolving, and then the Li.sub.xP.sub.y solid, the Na.sub.mP.sub.n solid or the K.sub.pP.sub.q solid is soaked in the electrolyte solvent for dissolving to obtain the electrolyte with the Li.sub.xP.sub.y, the Na.sub.mP.sub.n or the K.sub.pP.sub.q dissolved respectively.
[0319] According to some implementations of the present application, the additive is added to the electrolyte in the inert gas atmosphere, such as the argon atmosphere. It is the same as common liquid injection environment, and additional steps are not required in industrial production.
[0320] The present application further discloses a secondary ion battery, including a cathode, an anode, a separator and the electrolyte.
[0321] According to some implementations of the present application, the secondary ion battery includes a lithium-ion battery, a sodium-ion battery or a potassium-ion battery; and
[0322] According to some implementations of the present application, the cathode of the lithium-ion battery is selected from one or more of LiCoO.sub.2, LiNiO.sub.2, LiMn.sub.2O.sub.4, LiNi.sub.0.5Mn.sub.1.5O.sub.4, Li.sub.3V.sub.2(PO.sub.4).sub.3, LiFePO.sub.4, LiNi.sub.xCo.sub.yMn.sub.1-x-yO.sub.2, LiNi.sub.xCo.sub.yAl.sub.1-x-yO.sub.2 and S, and preferably, the LiCoO.sub.2, the LiMn.sub.2O.sub.4, the LiFePO.sub.4, the LiNi.sub.0.5Co.sub.0.2Mn.sub.0.3O.sub.2 and the LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1. The above preferred cathode materials may be compatible with the lithium polyphosphate, and the lithium polyphosphate may decompose in a working voltage window of the cathode materials to achieve the effects of capacity compensation and CEI stabilization.
[0323] According to some implementations of the present application, the cathode of the sodium-ion battery is selected from one or more of sodium cobaltate, sodium manganate, sodium nickelate, sodium vanadate, sodium manganese phosphate, sodium iron phosphate, sodium vanadium phosphate, nickel-iron sodium manganate and sodium-rich sodium manganate, and preferably, the sodium manganate, the sodium vanadate and the sodium vanadium phosphate. The above preferred cathode materials may be compatible with the sodium polyphosphate, and the sodium polyphosphate will decompose in a working voltage window of the cathode materials to achieve the effects of capacity compensation and CEI stabilization.
[0324] According to some implementations of the present application, the cathode of the potassium-ion battery is selected from one or more of a Prussian blue analogue containing potassium, KMO.sub.2, K.sub.3V.sub.2(PO.sub.4).sub.2F.sub.3, KVOPO.sub.4, KVPO.sub.4F, K.sub.4Fe.sub.3(PO.sub.4).sub.2(P.sub.2O.sub.7) and KFeC.sub.2O.sub.4, and preferably, the Prussian blue analogue containing potassium and the K.sub.4Fe.sub.3(PO.sub.4).sub.2(P.sub.2O.sub.7), where M in the KMO.sub.2 is a transition metal. The above preferred cathode materials may be compatible with the potassium polyphosphate, and the potassium polyphosphate will decompose in a working voltage window of the cathode materials to achieve the effects of capacity compensation and CEI stabilization.
[0325] According to some implementations of the present application, the anode is selected from artificial graphite, natural graphite, a carbon-based anode, a carbon nanotube, silicon and alloys thereof, tin and alloys thereof, germanium and alloys thereof, a phosphorus-based anode, a lithium metal, Li.sub.4Ti.sub.5O.sub.12 or a transition metal compound M.sub.iX.sub.k, where, M is a metal element, X is selected from O, S, F or N, 0<i<3, and 0<k<4.
[0326] According to some implementations of the present application, the M.sub.iX.sub.k is selected from Fe.sub.2O.sub.3, Co.sub.3O.sub.4, MoS.sub.2 and SnO.sub.2.
[0327] According to some implementations of the present application, the anode is preferably selected from the graphite, the red phosphorus-CNT complex the nano-silicon, the Li metal, the MoS.sub.2 and the black phosphorus-graphite complex. The above preferred anode materials may be compatible with polyphosphides, and the polyphosphides may decompose in a working voltage window of the cathode materials to achieve the effects of capacity compensation and SEI stabilization.
[0328] According to some implementations of the present application, a cathode/anode system is selected from the group consisting of LiNi.sub.0.5Co.sub.0.2Mn.sub.0.3O.sub.2/red phosphorus-CNT, LiNi.sub.0.5Co.sub.0.2Mn.sub.0.3 O.sub.2/nano-silicon, LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2/graphite, LiCoO.sub.2/SnO.sub.2, LiMn.sub.2O.sub.4/Li metal, LiFePO.sub.4/graphite, LiFePO.sub.4/MoS.sub.2, NaV.sub.6O.sub.15/black phosphorus-graphite complex and potassium-containing Prussian blue/graphite. In the above battery system, the additives Li.sub.xP.sub.y, Na.sub.mP.sub.n and K.sub.pP.sub.q may decompose in a voltage window of the battery preferentially, and form uniform and stable CEI and SEI films on the surfaces of the cathode and the anode.
[0329] According to some implementations of the present application, the concentration of the electrolyte salt is not specifically limited. For example, the concentration is 1.0 mol/L or 1.2 mol/L.
[0330] According to some implementations of the present application, the electrolyte may further include other additives. As the additive in the present disclosure is higher in compatibility with the electrolyte, selection of other additives is not specifically limited. Those skilled in the art may add common additives (such as film-forming additives, that is, fluoroethylene carbonate (FEC), vinylene carbonate (VC) and phenyl sulfone (PS)) according to specific battery systems.
[0331] The present application further discloses the application of the additive, the electrolyte and the secondary ion battery in the field of secondary rechargeable batteries.
[0332] The present disclosure will be described in detail below with reference to specific embodiments. Apparently, the listed embodiments are only a part of embodiments rather than all embodiments. Features in the embodiments can be mutually combined. All other embodiments obtained by those ordinarily skilled in art based on the present disclosure without involving creative labor should fall within the protection scope of the present disclosure. Conditions used by comparative examples are shown in Table 1.
Embodiment 1
[0333] An electrolyte in this embodiment includes organic solvents according to a volume ratio of EC/EMC/DMC=1/1/1, and a 1.0 mol/L LiFSI electrolyte salt is dissolved. Red phosphorus is added to a 1.0 mol/L Li-biphenyl tetrahydrofuran solution, a molar ratio of the red phosphorus to Li-biphenyl is 1:3, and the solution is stirred at 25° C. for 12 hours to obtain a solid product. The product is Li.sub.2.9P through inductively coupled plasma (ICP) elemental analysis. The phosphorus-containing compound is added to the electrolyte, and soaked for 20 hours to obtain the electrolyte with lithium polyphosphates dissolved. In the dissolved product, Li:P=1:7.8. Through mass spectrometry (as shown in
Embodiment 2
[0334] An electrolyte in this embodiment includes organic solvents according to a volume ratio, namely EC/DMC=2/1, and a 1.2 mol/L LiBF.sub.4 electrolyte salt is dissolved in the electrolyte. Red phosphorus is added to a 0.8 mol/L Li-biphenyl dimethoxyethane solution, a molar ratio of the red phosphorus to Li-biphenyl is 7:1, and the solution is stirred at 30° C. for 15 hours to obtain a solid product. The product is LiP.sub.6.4 through ICP elemental analysis. The phosphorus-containing compound is added to the electrolyte, and soaked for 12 hours to obtain the electrolyte with lithium polyphosphates dissolved. In the dissolved product, Li:P=1:8.5. Through mass spectrometry, the additives dissolved in the electrolyte solvent mainly include LiP.sub.7, LiP.sub.8 and LiP.sub.10, and the mass percentage of the additives is 5%. Taking LiNi.sub.0.5Co.sub.0.2Mn.sub.0.3O.sub.2 as a cathode material and nano-silicon as an anode material, the above electrolyte is added for assembling a CR2032 type coin cell.
Embodiment 3
[0335] An electrolyte in this embodiment includes organic solvents according to a volume ratio of EC/DEC=1/1, and a 1.0 mol/L LiPF.sub.6 electrolyte salt is dissolved. Red phosphorus is added to a 1.0 mol/L Li-biphenyl tetrahydrofuran solution, a molar ratio of the red phosphorus to Li-biphenyl is 2:1, and the solution is stirred at 30° C. for 10 hours to obtain a solid product. The product is LiP.sub.1.9 through ICP elemental analysis. The phosphorus-containing compound is added to the electrolyte, and soaked for 20 hours to obtain the electrolyte with lithium polyphosphates dissolved. In the dissolved product, Li:P=1:5.6. Through mass spectrometry, the additives dissolved in the electrolyte solvent mainly include LiP, LiP.sub.4 and LiP.sub.8, and the mass percentage of the additives is 15%. Taking LiNi.sub.0.5Co.sub.0.2Mn.sub.0.3O.sub.2 as a cathode material and the red phosphorus and CNT (the mass ratio is 7:3) subjected to ball milling as anode materials, the above electrolyte is added for assembling a CR2032 type coin cell.
Embodiment 4
[0336] An electrolyte in this embodiment includes organic solvents according to a volume ratio of EC/DEC=1/1, and a 1.2 mol/L LiTFSI electrolyte salt is dissolved in the electrolyte. Red phosphorus is added to a 1.2 mol/L Li-biphenyl dimethoxyethane solution, a molar ratio of the red phosphorus to Li-biphenyl is 5:1, and the solution is stirred at 35° C. for 20 hours to obtain a solid product. The product is LiP.sub.4.8 through ICP elemental analysis. The phosphorus-containing compound is added to the electrolyte, and soaked for 24 hours to obtain the electrolyte with lithium polyphosphates dissolved. In the dissolved product, Li:P=1:5.2. Through mass spectrometry, the additives dissolved in the electrolyte solvent mainly include LiP, LiP.sub.4, LiP.sub.5 and LiP.sub.10, and the mass percentage of the additives is 0.1%. Taking LiCoO.sub.2 as a cathode material and SnO.sub.2 as an anode material, the above electrolyte is added for assembling a CR2032 type coin cell.
Embodiment 5
[0337] An electrolyte in this embodiment includes organic solvents according to a volume ratio of 1, 3-DOL/DME=1/1, and a 1.0 mol/L LiBOB electrolyte salt is dissolved in the electrolyte. Red phosphorus is added to a 2.0 mol/L Li-biphenyl dimethoxyethane solution, a molar ratio of the red phosphorus to Li-biphenyl is 3:1, and the solution is stirred at 40° C. for 2 hours to obtain a solid product. The product is LiP.sub.2.7 through ICP elemental analysis. The phosphorus-containing compound is added to the electrolyte, and soaked for 48 hours to obtain the electrolyte with lithium polyphosphates dissolved. In the dissolved product, Li:P=1:6.3. Through mass spectrometry, the additives dissolved in the electrolyte solvent mainly include LiP, LiP.sub.5 and LiP.sub.10, and the mass percentage of the additives is 25%. Taking LiMn.sub.2O.sub.4 as a cathode material and a Li metal as an anode material, the above electrolyte is added for assembling a CR2032 type coin cell.
Embodiment 6
[0338] An electrolyte in this embodiment includes organic solvents according to a volume ratio of EC/DEC=1/1, and a 1.0 mol/L LiPF.sub.6 electrolyte salt is dissolved. Red phosphorus is added to a 1.0 mol/L Li-biphenyl tetrahydrofuran solution, a molar ratio of the red phosphorus to Li-biphenyl is 7:3, and the solution is stirred at 30° C. for 30 hours to obtain a solid product. The product is Li.sub.3P.sub.6.7 through ICP elemental analysis. The phosphorus-containing compound is added to the electrolyte, and soaked for 6 hours to obtain the electrolyte with lithium polyphosphates dissolved. In the dissolved product, Li:P=1:7.3. Through mass spectrometry, the additives dissolved in the electrolyte solvent mainly include LiP.sub.8, LiP.sub.7 and LiP.sub.10, and the mass percentage of the additives is 8%. Taking LiFePO.sub.4 as a cathode material and graphite as an anode material, the above electrolyte is added for assembling a CR2032 type coin cell.
Embodiment 7
[0339] An electrolyte in this embodiment includes organic solvents according to a volume ratio of EC/DEC=1/1, and a 1.0 mol/L LiPF.sub.6 electrolyte salt is dissolved. Red phosphorus is added to a 1.0 mol/L Li-biphenyl tetrahydrofuran solution, a molar ratio of the red phosphorus to Li-biphenyl is 4:1, and the solution is stirred at 25° C. for 11 hours to obtain a solid product. The product is LiP.sub.3.8 through ICP elemental analysis. The phosphorus-containing compound is added to the electrolyte, and soaked for 20 hours to obtain the electrolyte with lithium polyphosphates dissolved. In the dissolved product, Li:P=1:5.4. Through mass spectrometry, the additives dissolved in the electrolyte solvent mainly include LiP, LiP.sub.5 and LiP.sub.7, and the mass percentage of the additives is 10%. Taking LiFePO.sub.4 as a cathode material and MoS.sub.2 as an anode material, the above electrolyte is added for assembling a CR2032 type coin cell.
Embodiment 8
[0340] An electrolyte in this embodiment includes organic solvents according to a volume ratio of EC/DMC=1/1, and a 1.0 mol/L NaClO.sub.4 electrolyte salt is dissolved in the electrolyte. Red phosphorus is added to a 1.0 mol/L Na-biphenyl tetrahydrofuran solution, a molar ratio of the red phosphorus to Na-biphenyl is 7:3, and the solution is stirred at 25° C. for 12 hours to obtain a solid product. The product is Na.sub.3P.sub.6.7 through ICP elemental analysis. The phosphorus-containing compound is added to the electrolyte, and soaked for 20 hours to obtain the electrolyte with sodium polyphosphates dissolved. In the dissolved product, Na:P=1:5.4. Through mass spectrometry, the additives dissolved in the electrolyte solvent mainly include NaP.sub.5 and NaP.sub.7, and the mass percentage of the additives is 10%. Taking NaV.sub.6O.sub.15 (sodium vanadate) as a cathode material and a black phosphorus-graphite complex as an anode material, the above electrolyte is added for assembling a CR2032 type coin cell.
Embodiment 9
[0341] An electrolyte in this embodiment includes organic solvents according to a volume ratio of EC/DEC=1/1, and a 1.0 mol/L KFSI electrolyte salt is dissolved in the electrolyte. Red phosphorus is added to a 1.0 mol/L K-biphenyl tetrahydrofuran solution, a molar ratio of the red phosphorus to K-biphenyl is 1:3, and the solution is stirred at 25° C. for 12 hours to obtain a solid product. The product is K.sub.2.9P through ICP elemental analysis. The phosphorus-containing compound is added to the electrolyte, and soaked for 20 hours to obtain the electrolyte with potassium polyphosphates dissolved. In the dissolved product, K:P=1:5.8. Through mass spectrometry, the additives dissolved in the electrolyte solvent mainly include KP.sub.7 and K.sub.3P.sub.7, and the mass percentage of the additives is 10%. The electrolyte salt is 1.0 mol/L KFSI, the additive is KP.sub.7, and the mass percentage of the additive is 10%. Taking potassium-containing Prussian blue as a cathode material and graphite as an anode material, the above electrolyte is added for assembling a CR2032 type button battery.
Comparative Example 1
[0342] An electrolyte in this embodiment includes organic solvents according to a volume ratio of EC/DEC=1/1, and an electrolyte salt is 1.0 mol/L LiPF.sub.6. Taking LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 as a cathode materials and artificial graphite as an anode material, the above electrolyte is added for assembling a CR2032 type button battery.
Comparative Example 2
[0343] An electrolyte in this embodiment includes organic solvents according to a volume ratio of EC/DEC=1/1, and an electrolyte salt is 1.0 mol/L LiPF.sub.6. Taking LiFePO.sub.4 as a cathode material and graphite as an anode material, the above electrolyte is added for assembling a CR2032 type button battery.
Comparative Example 3
[0344] An electrolyte in this embodiment includes organic solvents according to a volume ratio of EC/DMC=1/1, and an electrolyte salt is 1.0 mol/L NaClO.sub.4. Taking NaV.sub.6O.sub.15 (sodium vanadate) as a cathode material and graphite as an anode material, the above electrolyte is added for assembling a CR2032 type button battery.
Comparative Example 4
[0345] An electrolyte in this embodiment includes organic solvents according to a volume ratio of EC/DEC=1/1, and an electrolyte salt is 1.0 mol/L KFSI. Taking potassium-containing Prussian blue as a cathode material and graphite as an anode material, the above electrolyte is added for assembling a CR2032 type button battery.
TABLE-US-00001 TABLE 1 No. Group Additive Electrolyte salt Solvent Cathode/anode 1 Embodiment 1 LiP.sub.7.8 10 wt % l.0 mol/L LiPF.sub.6 EC/EMC/DMC = 1/1/1 LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2/ (LiP.sub.5, LiP.sub.7, LiP.sub.10) Artificial graphite 2 Embodiment 2 LiP.sub.8..sub.5 5 wt % 1.2 mol/L LiBF.sub.4 EC/DEC = 2/1 LiNi.sub.0.5Co.sub.0.2Mn.sub.0.3O.sub.2/ (LiP.sub.7, LiP.sub.8, LiP.sub.10) Nano-silicon 3 Embodiment 3 LiP.sub.5..sub.6 15 wt % l.0 mol/L LiPF.sub.6 EC/DEC = 1/1 LiNi.sub.0.5Co.sub.0.2Mn.sub.0.3O.sub.2/ (LiP, LiP.sub.4, LiP.sub.8) Red phosphorus-CNT 4 Embodiment 4 LiP.sub.5.2 0.1 wt % 1.2 mol/L LiTFSI EC/DEC = 1/1 LiCoO.sub.2/SnO.sub.2 (LiP, LiP.sub.4, LiP.sub.5, LiP.sub.10) 5 Embodiment 5 LiP.sub.6.3 25 wt % l.0 mol/L LiBOB 1,3-DOL/DME = 1/1 LiMn.sub.2O.sub.4/Li metal (LiP, LiP.sub.5, LiP.sub.10) 6 Embodiment 6 LiP.sub.7.3 8 wt % l.0 mol/L LiPF.sub.6 EC/DEC = 1/1 LiFePO.sub.4/graphite (LiP.sub.5, LiP.sub.7, LiP.sub.10) 7 Embodiment 7 LiP.sub.5.4 10 wt % l.0 mol/L LiPF.sub.6 EC/DEC = 1/1 LiFePO.sub.4/MoS.sub.2 (LiP, LiP.sub.5, LiP.sub.7) 8 Embodiment 8 NaP.sub.5.4 10 wt % 1.0 mol/L NaClO.sub.4 EC/DMC = l/l NaV.sub.6O.sub.15/black (NaP.sub.5, NaP.sub.7) phosphorus-graphite complex 9 Embodiment 9 K.sub.2..sub.9P 10 wt % 1.0 mol/L KFSI EC/DEC = 1/1 Potassium-containing (KP.sub.7, K.sub.3P.sub.7) Prussian blue/graphite 10 Comparative No l.0 mol/L LiPF.sub.6 EC/DEC = 1/1 LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2/ Example 1 Artificial graphite 11 Comparative No l.0 mol/L LiPF.sub.6 EC/DEC = 1/1 LiFePO.sub.4/graphite Example 2 12 Comparative No 1.0 mol/L NaClO.sub.4 EC/DMC = l/l NaV.sub.6O.sub.15/black Example 3 phosphorus-graphite complex 13 Comparative No l.0 mol/L KFSI EC/DEC = 1/1 Potassium-containing Example 4 Prussian blue/graphite
[0346] The battery is activated at a charge-discharge current density of 20 mAh g.sup.−1/20 mAh g.sup.−1 in an environment at 25° C. within a voltage interval of 3.0 V to 4.3 V in Embodiments 1 to 5 and 9 and the comparative examples 1 and 4, and then cycle performance tests are conducted at 100 mAh g.sup.−1/100 mAh g.sup.−1 within the voltage interval of 3.0 V to 4.3 V. The capacity of the activated battery after the first discharge was D1, meanwhile, the capacity of the battery after 200 cycles was recorded as D200, D200/D1 was the capacity retention rate of the battery, and obtained results were shown in Table 2.
[0347] The battery is activated at a charge-discharge current density of 20 mAh g.sup.−1/20 mAh g.sup.−1 in an environment at 25° C. within a voltage interval of 2.0 V to 3.8 Vin the embodiments 6 to 8 and the comparative examples 2 and 3, and then cycle performance tests are conducted at 100 mAh g.sup.−1/100 mAh g.sup.−1 within the voltage interval of 2.0 V to 3.8 V. The capacity of the activated battery after the first discharge was D1, meanwhile, the capacity of the battery after 200 cycles was recorded as D200, D200/D1 was the capacity retention rate of the battery, and obtained results were shown in Table 2.
TABLE-US-00002 TABLE 2 First-cycle Capacity coulombic D1 retention No. Group efficiency (%) (mAh g.sup.-1) rate (%) 1 Embodiment 1 84.4 204.1 74.3 2 Embodiment 2 84.5 207.5 71.0 3 Embodiment 3 84.7 211.9 72.6 4 Embodiment 4 85.0 212.4 73.4 5 Embodiment 5 84.9 143.4 69.2 6 Embodiment 6 88.2 145.8 79.9 7 Embodiment 7 86.9 148.3 70.6 8 Embodiment 8 85.6 120.2 84.0 9 Embodiment 9 61.2 109.2 73.1 10 Comparative 84.3 202.3 52.0 example 1 11 Comparative 84.1 142.9 67.0 example 2 12 Comparative 83.4 118.5 74.3 example 3 13 Comparative 60.7 105.6 60.3 example 4
[0348]
[0349]
[0350]
[0351] From the dissolved product of the prepared Li.sub.xP.sub.y compound in the electrolyte solvent in Table 1, it can be seen that the LiP, LiP.sub.4, LiP.sub.5, LiP.sub.7 and LiP.sub.10 were higher in solubility, which might decompose to release the active ions and electrons for capacity compensation as the electrolyte additives.
[0352] From the capacity retention rate data of the lithium-ion battery system in Table 2, it can be seen that the capacity retention rates in the embodiment 1 and the embodiment 6 were higher, which showed that when the mass percentage of the additives was 8% to 12%, a better capacity compensation effect could be achieved.
[0353] From the data of the embodiment 8 and the comparative example 3 in Table 2, it can be seen that in the sodium-ion battery system, after 10 wt % of NaP.sub.7 was added in the NaV.sub.6O.sub.15/black phosphorus-graphite complex full battery, the NaP.sub.7 may play a role in compensating sodium ions and electrons to improve the initial Coulombic efficiency and cycle stability of the full battery.
[0354] From the data of the embodiment 9 and the comparative example 4 in Table 2, it can be seen that in the potassium-ion battery system, after 10 wt % of KP.sub.7 was added in the potassium-containing Prussian blue/graphite full battery, the KP.sub.7 may play a role in compensating potassium ions and electrons to improve the initial Coulombic efficiency and cycle stability of the full battery.
[0355] In conclusion, through extensive experimental validation, it can be found obviously from the data in Table 2 that in the lithium-ion battery, the initial Coulombic efficiency of the battery containing the Li.sub.xP.sub.y additive was improved compared with that in the comparative example, which proved that the Li.sub.xP.sub.y additive might play a role in capacity compensation in the first charging cycle; and the capacity retention rate in each battery system was improved compared with the comparative examples, which proved that the Li.sub.xP.sub.y additive might play a role in stabilizing the cathode CEI layer and the anode SEI layer to achieve better cycle performance. It can be seen from comparison that the content of the additives had a certain effect on the initial Coulombic efficiency and cycle stability of the battery. After the Na.sub.mP.sub.n and K.sub.pP.sub.q were added to the sodium and potassium-ion batteries, the first-cycle reversible capacity of the battery was also improved, which was related to the phosphorus-containing substance decomposing to release the active ions, and the higher capacity retention rate of the battery was related to P.sub.y.sup.− synergistic participation in formation of the more stable CEI and SEI layers.
[0356] The embodiments shown in the present specification are not intended to limit the implementation of the present disclosure, but are merely descriptive of the present disclosure. Those ordinarily skilled in the art can also make other modifications or variations of different forms on the basis of the above illustration.