PRE-LITHIATED LITHIUM ION POSITIVE ELECTRODE MATERIAL, AND PREPARATION METHOD THEREFOR AND USE THEREOF

Abstract

Disclosed are a pre-lithiated lithium ion positive electrode material, a preparation method therefor and use thereof. The lithium ion positive electrode material has a chemical formula of Li.sub.2O/[A.sub.(3-x)Me.sub.x].sub.1/3-LiAO.sub.2, wherein A comprises M, and wherein M is at least one of Ni, Co, and Mn; and wherein Me is at least one of Ni, Mn, Al, Mg, Ti, Zr, Y, Mo, W, Na, Ce, Cr, Zn or Fe; and wherein 0 < × < 0.1. The material is co-doped with multiple elements, and these elements act synergistically to inhibit the irreversible phase change at a high voltage and improve the stability of the structure of a substrate. The spinel phase A.sub.(3-x)Me.sub.xO.sub.4 structure contains the doping elements, which work together to improve the interfacial activity of the material and introduce more electrochemically active sites.

Claims

1. A pre-lithiated lithium ion positive electrode material, which has a chemical formula of Li.sub.2O/[A.sub.(3-x)Me.sub.x].sub.1/3-LiAO.sub.2, wherein A comprises M, and wherein M is at least one of Ni, Co, and Mn; and wherein Me is at least one of Ni, Mn, Al, Mg, Ti, Zr, Y, Mo, W, Na, Ce, Cr, Zn or Fe; and wherein 0 < × < 0.1; wherein the lithium ion positive electrode material has a shallow surface layer being capable of forming a spinel phase A.sub.(3-x)Me.sub.x structure.

2. The pre-lithiated lithium ion positive electrode material of claim 1, wherein A further comprises M′, and wherein M′ is at least one of Mg, Ti, Zr, Y, Ce, Sr, La or Al.

3. The pre-lithiated lithium ion positive electrode material of claim 1, wherein LiAO.sub.2 in the Li.sub.2O/[A.sub.(3-x)Me.sub.x].sub.1/3-LiAO.sub.2 is LiNi.sub.(1-m-n)Co.sub.nMn.sub.mO.sub.2, with 0 ≤ m ≤ 1 and 0 ≤ n ≤ 1.

4. A method for preparing the pre-lithiated lithium ion positive electrode material of claim 1, comprising: (1) preparing a sulfate solution of A, then adding a precipitant and a complexing agent, and stirring and reacting to obtain a precursor slurry; (2) subjecting the precursor slurry to centrifugation, drying, and sieving to obtain a precursor; (3) mixing a lithium source with the precursor, and calcining and crushing to obtain a lithium ion positive electrode material; and (4) adding the lithium ion positive electrode material to a pre-lithiation solution, and stirring, aging, drying, and tempering to obtain Li.sub.2O/[A.sub.(3-x)Me.sub.x].sub.1/3-LiAO.sub.2, wherein the pre-lithiation solution comprises: a lithium source, Me and a conjugate, wherein Me is at least one of Ni, Mn, Al, Mg, Ti, Zr, Y, Mo, W, Na, Ce, Cr, Zn or Fe; and the conjugate is selected from a group consisting of a naphthalene-containing conjugate, citric acid conjugate or tartaric acid conjugate containing a hydroxyl + carboxyl combination, a carboxyl + carbon-carbon double bond combination, a hydroxyl + carbon-carbon double bond combination, a hydroxyl + carboxyl + carbon-carbon double bond combination, or a carbon-carbon double bond + carbonyl combination.

5. The method of claim 4, wherein the naphthalene-containing conjugate is at least one of naphthalene, naphthoquinone, naphthalene sulfonic acid, naphthalene sulfuric acid, naphthalene nitric acid, naphthalene boric acid, or naphthalene titanic acid.

6. The method of claim 4, wherein the lithium source in step (3) is at least one of lithium carbonate, lithium oxide or lithium hydroxide.

7. The method of claim 4, wherein in step (3), the molar ratio of Li in the lithium source to the element A in the precursor is (1.01-1.07) : 1, and wherein M′ in A is a doping element, and the source of M′ is at least one of a metal powder, oxide, fluoride, hydroxide, phosphate, or carbonate containing the element.

8. The method of claim 4, wherein pre-lithiation solution in step (4) is prepared by: adding a conjugate, a lithium source and Me to an aqueous solution, and stirring and dissolving.

9. The method of claim 8, wherein the aqueous solution is at least one of a nitric acid solution, a sulfuric acid solution, a sodium hydroxide solution or an ethanol solution.

10. A lithium ion battery, comprising the pre-lithiated lithium ion positive electrode material of claim 1.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0045] FIG. 1 is an XPS pattern of the pre-lithiated sample of Embodiment 1 and the sample of Comparative Example 8 without a pre-lithiation treatment;

[0046] FIG. 2 is an XPS pattern of the sample of Embodiment 1 after the first charge - discharge;

[0047] FIG. 3 is SEM images of the sample of Embodiment 1 and the sample of Comparative Example 8; and

[0048] FIG. 4 is XRD patterns of the samples of Embodiment 1 and the sample of Comparative Example 8 after the first discharge.

DETAILED DESCRIPTION

[0049] In order to make those skilled in the art more clearly understand the technical solution of the disclosure, the following embodiments are set forth for description. It should be noted that the following embodiments do not constitute a limitation on the protection scope of the disclosure.

[0050] Unless otherwise specially stated, the raw materials, reagents or devices used in the following embodiments can all be obtained from conventional commercial sources, or can be obtained by existing known methods.

[0051] The disclosure adopts the following preparation method to synthesize a positive electrode material, wherein the positive electrode material can be simply described as: a material comprising a bulk phase doped with Al, Mg and Zr and a shallow layer doped with Al and Ti (the molar ratios of doping elements Al and Ti to Co in the shallow layer are respectively 0.5% and 0.25%). It should be noted that the “molar ratio” refers to the ratio of the moles of Al and Ti atoms participating in the reaction to the moles of Co atoms participating in the reaction. For example, the expression “the molar ratios of Al and Ti to Co are respectively 0.5% and 0.25%” means that for 1 mol of LiCoO.sub.2, 0.25% mol of Al.sub.2O.sub.3 and 0.25% mol of TiO.sub.2 are used for reaction therewith.

Embodiment 1

[0052] The pre-lithiated lithium ion positive electrode material of Embodiment 1 has a chemical formula of (Li.sub.2O/[Co.sub.2.95(TiAl).sub.0.05].sub.1/3).sub.0.01.Math.(Li.sub.1.01Co.sub.0.96Mg.sub.0.008Al.sub.0.024Zr.sub.0.008O.sub.2).sub.0.99.

[0053] A pre-lithiation solution (a solution containing naphthalene-lithium-Me) is prepared by mixing naphthalene, lithium carbonate, and Al and Ti, then adding a sulfuric acid solution, and stirring, wherein the naphthalene and the lithium carbonate are mixed at a molar ratio of 2 : 1.

[0054] A method for preparing the pre-lithiated lithium ion positive electrode material comprises the following steps: [0055] (1) preparing 200 L of cobalt sulfate solution with a concentration of 0.4 mol/L, preparing 6.25 L of magnesium sulfate solution with a concentration of 0.1 mol/L, preparing 9.0 L of aluminum sulfate with a concentration of 0.2 mol/L, preparing 6.25 L of zirconium sulfate with a concentration of 0.1 mol, mixing, adding 30% liquid caustic soda and 25% analytically pure aqueous ammonia, stirring at a rate of 300 rpm, controlling the pH to 10.8, and reacting at 55° C. for 20 hours to obtain a precursor slurry; [0056] (2) subjecting the precursor slurry to centrifugation, washing, filtration, drying at 110° C. for 8 h, and then sieving to obtain a spheroid precursor doped with magnesium, aluminum and zirconium; [0057] (3) mixing the spheroid precursor doped with magnesium, aluminum and zirconium with lithium carbonate at a molar ratio of Li : (Co+Mg+Al+Zr) of 1.04 : 1 to obtain a mixture, calcining the mixture in air at 720° C. for 4 h, then sintering at 1035° C. for 8 h, and crushing to obtain a lithium cobaltate positive electrode material doped with Zr, Mg and Al; and [0058] (4) adding the lithium cobaltate positive electrode material doped with Mg, Al and Y to a pre-lithiation solution, stirring for 5 minutes, and then subjecting to aging, drying, and tempering at 500° C. for 30 min to obtain a lithium ion positive electrode material with a pretreated layer N1, namely (Li.sub.2O/[Co.sub.2.95(TiAl).sub.0.05].sub.1/3).sub.0.01.Math.(Li.sub.1.01Co.sub.0.96Mg.sub.0.008Al.sub.0.024Zr.sub.0.008O.sub.2).sub.0.99.

Embodiment 2

[0059] The pre-lithiated lithium ion positive electrode material of Embodiment 2 has a chemical formula of (Li.sub.2O/[CO.sub.2.94(TiAl).sub.0.06].sub.1/3).sub.0.02.Math.(Li.sub.1.01CO.sub.0.96Mg.sub.0.008Al.sub.0.024Y.sub.0.008O.sub.2).sub.0.98.

[0060] The preparation method is roughly the same as in Embodiment 1, and the main difference lies in that in Embodiment 2, the doping elements in the precursor are magnesium, aluminum, and yttrium, the tempering temperature is 450° C., and the pretreated layer N2 produced from the pre-lithiation treatment has a total mass accounting for 2.0% of the total mass of the material.

Embodiment 3

[0061] The pre-lithiated lithium ion positive electrode material of Embodiment 3 has a chemical formula of (Li.sub.2O/[CO.sub.2.92(TiAl).sub.0.08].sub.1/3).sub.0.015.Math.(Li.sub.1.01CO.sub.0.96Mg.sub.0.008Al.sub.0.02Y.sub.0.008Ti.sub.0.004O.sub.2).sub.0.985.

[0062] The preparation method is roughly the same as in Embodiment 1, and the main difference lies in that in Embodiment 3, the doping elements in the precursor are magnesium, aluminum, yttrium and titanium, the tempering time is 1 h, and the pretreated layer N3 produced from the pre-lithiation treatment has a total mass accounting for 1.5% of the total mass of the material.

Embodiment 4

[0063] The preparation method is roughly the same as in Embodiment 1, and the main difference lies in that in Embodiment 4, the doping elements in the precursor are aluminum, yttrium and lanthanum with a ratio of Li : (Co+Y+La+Al) = 1.05: 1, and the pretreated layer N4 produced from the pre-lithiation treatment has a total mass accounting for 1.5% of the total mass of the material.

Embodiment 5

[0064] The preparation method is roughly the same method as in Embodiment 1, and the main difference lies in that the solution provided for the pretreatment in Embodiment 5 is naphthalene boric acid-lithium-Me.

Embodiment 6

[0065] The preparation method is roughly the same as in Embodiment 1, and the main difference lies in that in Embodiment 6, the precursor is nickel cobalt manganese hydroxide (Ni : Co : Mn = 5:2:3), and the pretreated layer N6 produced from the pre-lithiation treatment has a total mass of the pretreated layer N6 accounting for 1.0% of the total mass of the material.

Embodiment 7

[0066] The preparation method is roughly the same as in Embodiment 1, and the main difference lies in that in Embodiment 7, the precursor is nickel hydroxide, the doping elements in the precursor are magnesium, manganese, and cobalt, and the pretreated layer N7 produced from the pre-lithiation treatment has a total mass of the pretreated layer N7 accounting for 4.5% of the total mass of the material.

Comparative Example 1

[0067] The lithium ion positive electrode material of Comparative Example 1 has a chemical formula of Li.sub.1.01CO.sub.0.96Mg.sub.0.008Al.sub.0.024Zr.sub.0.008O.sub.2.

[0068] A method for preparing the lithium ion positive electrode material is provided, which comprises the following steps: [0069] (1) preparing 200 L of cobalt sulfate solution with a concentration of 0.4 mol/L, preparing 6.25 L of magnesium sulfate solution with a concentration of 0.1 mol/L, preparing 9.0 L of aluminum sulfate with a concentration of 0.2 mol/L, preparing 6.25 L of zirconium sulfate with a concentration of 0.1 mol, mixing, adding 30% liquid caustic soda and 25% analytically pure aqueous ammonia, stirring at a rate of 300 rpm, controlling the pH to 10.8, and reacting at 55° C. for 20 hours to obtain a precursor slurry; [0070] (2) subjecting the precursor slurry to centrifugation, washing, filtration, drying at 110° C. for 8 h, and then sieving to obtain a spheroid precursor doped with magnesium, aluminum and zirconium; and [0071] (3) mixing the spheroid precursor doped with magnesium, aluminum and zirconium with lithium carbonate at a molar ratio of Li : (Co+Mg+Al+Zr) of 1.04 : 1 to obtain a mixture, calcining the mixture in air at 720° C. for 4 h, then sintering at 1035° C. for 8 h, and crushing to obtain a lithium cobaltate positive electrode material doped with Zr, Mg and Al; and [0072] (4) mixing the lithium cobaltate positive electrode material doped with Zr, Mg and Al with lithium carbonate, an aluminum salt, and a titanium salt, wherein the amounts of lithium, aluminum and titanium added the second time are exactly the same as those in Embodiment 1, and tempering at 500° C. for 30 min to obtain the positive electrode material with the composition being L wherein M1 is a mixed coating layer composed of Li, Co, Al, Ti and O, and after direct tempering, the total mass of N1′ accounts for 1.0% of the total mass of the material.

[0073] The difference between Embodiment 1 and Comparative Example 1 lies in that Comparative Example 1 has no surface layer pre-lithiation treatment, and relates to directly coating the same substance with a solid phase and then tempering and sintering to obtain a product.

[0074] Comparative Example 2 adopts roughly the same method as in Embodiment 2, and the difference lies in that Comparative Example 2 has no pre-lithiation treatment, and the material N2′ produced from directly tempering accounts for 2.0% of the total mass after direct tempering.

[0075] Comparative Example 3 adopts roughly the same method as in Embodiment 3, and the difference lies in that Comparative Example 3 has no pre-lithiation treatment, and the material N3′ produced from directly tempering accounts for 1.5% of the total mass after direct tempering.

[0076] Comparative Example 4 adopts roughly the same method as in Embodiment 4, and the difference lies in that Comparative Example 4 has no pre-lithiation treatment, and the material N4′ produced from directly tempering accounts for 1.5% of the total mass after direct tempering.

[0077] Comparative Example 5 adopts roughly the same method as in Embodiment 5, and the difference lies in that no naphthalene boric acid is added to the provided solution, and the solution only contains lithium and Me.

[0078] Comparative Example 6 adopts roughly the same method as in Embodiment 6, and the difference lies in that Comparative Example 6 has no pre-lithiation treatment, and the material N6′ produced from directly tempering accounts for 1.0% of the total mass after direct tempering.

[0079] Comparative Example 7 adopts roughly the same method as in Embodiment 7, and the difference lies in that Comparative Example 7 has no pre-lithiation treatment, and the material N7′ produced from directly tempering accounts for 4.5% of the total mass after direct tempering.

[0080] In the above embodiments and examples, Na (a = 1, 2, 3, ...), Na′ (a = 1, 2, 3, ...), wherein the Na and Na′ are in a one-to-one correspondence.

Application Example

Comparative Example 8

[0081] The lithium ion positive electrode material of Comparative Example 8 has a chemical formula of is Li.sub.1.01CO.sub.0.96Mg.sub.0.008Al.sub.0.024Zr.sub.0.008O.sub.2.

[0082] A method for preparing the lithium ion positive electrode material is provided, which comprises the following steps: [0083] (1) preparing 200 L of cobalt sulfate solution with a concentration of 0.4 mol/L, preparing 6.25 L of magnesium sulfate solution with a concentration of 0.1 mol/L, preparing 9.0 L of aluminum sulfate with a concentration of 0.2 mol/L, preparing 6.25 L of zirconium sulfate with a concentration of 0.1 mol, mixing, adding 30% liquid caustic soda and 25% analytically pure aqueous ammonia, stirring at a rate of 300 rpm, controlling the pH to 10.8, and reacting at 55° C. for 20 hours to obtain a precursor slurry; [0084] (2) subjecting the precursor slurry to centrifugation, washing, filtration, drying at 110° C. for 8 h, and then sieving to obtain a spheroid precursor doped with magnesium, aluminum and zirconium; and [0085] (3) mixing the spheroid precursor doped with magnesium, aluminum and zirconium with lithium carbonate at a molar ratio of Li : (Co+Mg+Al+Zr) of 1.04 : 1 to obtain a mixture, calcining the mixture in air at 720° C. for 4 h, then sintering at 1035° C. for 8 h, and crushing to obtain a lithium cobaltate positive electrode material doped with Zr, Mg and Al.

[0086] The difference between Embodiment 1 and Comparative Example 0 lies in that Comparative Example 0 has no surface layer pre-lithiation treatment.

[0087] The positive electrode materials obtained in the embodiments and comparative examples are manufactured into batteries for several performance tests, specifically as follows.

[0088] The lithium cobaltate positive electrode materials respectively obtained in Embodiment 1 and Comparative Examples 0 and 1, polyvinylidene fluoride, and conductive carbon are mixed at a mass ratio of 90:5:5, NMP is added, and the support slurry is stirred, applied to an aluminum foil and dried at 60° C. to make positive electrode pieces. The positive electrode pieces, a lithium piece as a negative electrode, an electrolyte solution and a separator, as raw materials, are assembled into CR2430 button batteries in a glove box.

[0089] At room temperature, the charge-discharge capacity is tested at a charge-discharge voltage of 3.0-4.55 V and a first charge-discharge rate of 0.1 C. At 25° C., the cycle performance is tested at a charge-discharge voltage of 3.0-4.65 V and a charge rate of 0.5 C for 50 cycles, and the 50-cycle capacity retention is determined by dividing the specific discharge capacity of the 52nd cycle by the specific discharge capacity of the 3rd cycle. The charge and discharge test results of the assembled button batteries of Embodiment 1 and Comparative Examples 0 and 1 are as shown below.

TABLE-US-00001 Example No. Doping elements in bulk phase Pre-lithiation treatment Weight ratio of N or N′ 3.0-4.55 V/0.1 C, First discharge capacity (mAh/g) 3.0-4.65 V/0.5 C, 50-cycle retention Embodiment 1 Mg, Al, Zr Yes N1 = 1.0% 201.33 90.6% Comparative Example 8 Mg, Al, Zr No 0% 199.62 30.2% Comparative Example 1 Mg, Al, Zr No N1′ = 1.0% 196.16 75.6%

[0090] By comparing Embodiment 1 and Comparative Example 8, it can be seen that the first discharge capacity of the pre-lithiated sample of Example 1 at 3.0-4.55 V/0.1 C is 201.33 mAh/g, whereas the capacity of Comparative Example 8 without a pre-lithiation treatment is 199.16 mAh/g, so the capacity of Embodiment 1 is better. For the 50-cycle retention at 3.0-4.65 V/0.5 C, it can be seen that the 50-cycle capacity retention of Embodiment 1 is 90.6%, whereas that of Comparative Example 8 drops to 30.2%. The sample obtained by direct solid phase coating without pretreatment in Comparative Example 1 has a first discharge capacity of 196.16 mAh/g and a 50-cycle capacity retention at 3.0-4.65 V/0.5 C of 75.6%. It can be seen from the comparison that Embodiment 1 is superior in both capacity and cycle.

[0091] The fast cycle decay of the sample of Comparative Example 8 is mainly due to the fact that the surface layer of the positive electrode material is not treated, which makes the surface layer be easily corroded during the cycles, and the structure is easily destroyed, which leads to a series of side reactions such as oxygen evolution, thus leading to the accelerated cycle decay. The sample of Comparative Example 1 has direct solid phase coating, wherein the surface layer is coated with an inert substance, which causes the blocked transport of ions and electrons and the decrease in capacity; furthermore, since the surface layer is coated with the inert substance, which provides a certain barrier effect between the positive electrode material and the electrolyte solution. Therefore, the cycle performance of the sample of Comparative Example 1 is improved as compared with that of Comparative Example 8.

[0092] As seen from FIG. 1, in the XPS pattern of the lithium cobaltate positive electrode material of Example 1 which has undergone the surface pretreatment, a 1s peak of Li is detected by XPS, indicating that lithium enters the material which has been treated in the naphthalene-lithium-Me-containing solution, making the surface layer or shallow layer of the material rich in lithium, whereas Comparative Example 8 which is not pre-treated does not contain a 1s peak of Li. It can be seen from FIG. 2 that after the first charge - discharge of Embodiment 1, the peak of Lls detected by XPS disappears, indicating that the lithium in the pre-treated surface or shallow layer is released during the first charge - discharge and replenishes the lithium battery system. It can be seen from FIG. 1 and FIG. 2 that Co 3p is basically unchanged, indicating that a stable spinel phase Co.sub.3O.sub.4 is formed in the surface layer after de-lithiation, and since the lithiation potential of Co.sub.3O.sub.4 is relatively low (< 2 V), i.e. much less than 3.0 V, no lithium intercalation would occur subsequently in the Co.sub.3O.sub.4, so that it keeps present in the form of Co.sub.3O.sub.4. In addition, the other doping elements in the surface layer increase the electron ion conductance of the surface layer, improve the potential balance of the surface layer, and further improve the stability of the surface layer.

[0093] It can be seen from FIG. 3 that, in the left image representing the pretreated Embodiment 1, the surface layer is obviously indicated to have been pre-treated, while in the right image representing Comparative Example 8, the surface is smooth without obvious change.

[0094] It can be seen from FIG. 4 that after the first charge - discharge of Embodiment 1, the corresponding sample is mainly composed of a lithium cobaltate phase and also has a small amount of Co.sub.3O.sub.4 structure phase, indicating that during the first charge - discharge process, a spinel structure Co.sub.3O.sub.4 is formed on the particle surface, whereas for Comparative Example 8, after the first charge-discharge, the sample only has a lithium cobaltate phase.

[0095] The sample of Embodiment 1 has superior electrochemical performance, mainly for the following reasons: (1) after the surface layer of the positive electrode material is pre-lithiated, the lithium ion “donor” capacity is high during the initial charge process, which makes up for the lithium loss during the initial discharge process, thereby increasing the discharge capacity and thus the energy density; (2) the doped spinel structure Co.sub.(3-x)Me.sub.xO.sub.4 is formed on the surface after the first discharge, and the spinel phase structure has three-dimensional de-intercalation and intercalation lithium channels, which are more conducive to the diffusion and migration of lithium ions as compared with ordinary layered two-dimensional structures; (2) the spinel phase structure and the doping metal elements work together to improve the interfacial activity of the material and introduce more electrochemically active sites; and (3) the doping metal elements in the surface of the positive electrode material also makes the interfacial properties more stable, thus ensuring the cycle stability.

[0096] The samples of Embodiments 2 and 3 and Comparative Examples 2 and 3 are tested at 25° C. for the capacity at a charge-discharge voltage of 3.0-4.55 V and a charge rate of 0.1 C and the cycle performance at a charge-discharge voltage of 3.0-4.65 V and a charge rate of 0.5 C for 50 cycles, and the 50-cycle capacity retention is determined by dividing the specific discharge capacity of the 52nd cycle by the specific discharge capacity of the 3rd cycle. The charge and discharge test results of the assembled button batteries of Embodiments 2 and 3 and Comparative Examples 2 and 3 are as shown below.

TABLE-US-00002 Example No. Doping elements in bulk phase Pre-lithiation treatment Weight ratio of N or N′ 3.0-4.55 V/0.1 C, First discharge capacity (mAh/g) 3.0-4.65 V/0.5 C, 50-cycle retention Embodiment 2 Mg, Al, Y Yes N2 = 2.0% 200.2 89.6% Embodiment 3 Mg, Al, Y, Ti Yes N3 = 1.5% 201.7 92.2% Comparative Example 2 Mg, Al, Y No N2′ = 2.0% 196.7 56.7% Comparative Example 3 Mg, Al, Y, Ti No N3′ = 1.5% 198.2 64.8%

[0097] From the results of Embodiments 2 and 3, it can be seen that after the pre-lithiation treatment, the proportion of N increases, and the cycle decreases slightly. In the case of N1 = 1.5%, since the surface layer coating is thinner, the pretreatment effect is better. From the increase of the pretreated layer versus the capacity, it can be seen that as the proportion of the pretreated layer increases, the surface becomes thicker, resulting in the longer electron ion channels and the slightly decrease capacity. It can be seen from Comparative Example 2 and Comparative Example 3 that the capacity and cycle performance are significantly improved after pretreatment.

TABLE-US-00003 Example No. Doping elements in bulk phase Pre-lithiation treatment Weight ratio of N or N′ Li :(Co+Me) 3.0-4.55 V/0.1 C, First discharge capacity (mAh/g) 3.0-4.65 V/0.5 C, 50-cycle retention Embodiment 4 Al, Y, La Yes N4 = 1.5% 1.05:1 202.2 88.63% Comparative Example 4 Al, Y, La No N4′ = 1.5% 1.05:1 201.3 76.3%

[0098] It can be seen from Table 3 that the cycle performance of the pre-lithiated sample (Example 4) is significantly better than that of the direct solid phase coated sample.

TABLE-US-00004 Example No. Doping elements in bulk phase Pre-lithiation solution Weight ratio of N or N′ 3.0-4.55 V/0.1 C, First discharge capacity (mAh/g) 3.0-4.65 V/0.5 C, 50-cycle retention Embodiment 5 Mg, Al, Zr Naphthalene boric acid-lithium-Me N5 = 1.0% 202.4 91.2% Comparative Example 5 Mg, Al, Zr Lithium-Me N5′ = 1.0% 197.2 78.2%

[0099] As shown in Table 4, Embodiment 5 has a better electrochemical performance as compared with Comparative Example 5. This is because lithium penetrates the surface layer of the material after the treatment with the pretreatment solution and interacts with the shallow layer of the substrate, making the shallow layer rich in lithium, and during the first charge - discharge process, the lithium-rich substance in the shallow layer can be converted to a spinel phase Co.sub.(3-x)Me.sub.xO.sub.4 structure, which can stabilize the structure under a high voltage, improving the cycle performance; in addition, excess lithium after the pre-lithiation makes up for the lithium loss during the first charge - discharge process, thereby increasing the first discharge capacity.

[0100] The samples of Embodiment 6 and Comparative Example 6 are tested at 25° C. for the capacity at a charge-discharge voltage of 3.0-4.35 V and a charge rate of 0.1 C and the cycle performance at a charge-discharge rate of 1.0 C for 50 cycles. The cycle calculation starts from the 3rd cycle, and the 50-cycle capacity retention is determined by dividing the specific discharge capacity of the 52nd cycle by the specific discharge capacity of the 3rd cycle. The charge and discharge test results of the assembled button batteries of Embodiment 6 and Comparative Example 6 are as shown in Table 5 below.

TABLE-US-00005 Example No. Doping elements in bulk phase Pre-lithiation solution Weight ratio of N or N′ 3.0-4.55 V/0.1 C, First discharge capacity (mAh/g) 3.0-4.65 V/0.5 C, 50-cycle retention Embodiment 6 Mg, Al, Zr Naphthalene boric acid-lithium-Me N6= 1.0% 180.5 91.2% Comparative Example 6 Mg, Al, Zr Lithium-Me N6′ = 1.0% 175.2 84.2%

[0101] From the results of Embodiment 6 and Comparative Example 6, it can be seen that with lithium nickel cobalt manganese oxide (5:2:3) as a substrate, the capacity and cycle performance are both improved after pretreatment. This is because lithium enters the shallow layer of the particles after pretreatment and is released during the first discharge, which makes up for the loss of lithium during the first discharge and increases the capacity, and after lithium is released from the surface layer, the shallow structure is transformed from a layered structure into a spinel phase Co.sub.(3-X)Me.sub.xO.sub.4 structure, which has three-dimensional de-intercalation and intercalation lithium channels, which are more conducive to the diffusion and migration of lithium ions as compared with ordinary layered two-dimensional structures; in addition, the spinel-like M.sub.(3-x)Me.sub.xO.sub.4 has a high voltage resistance and improved cycle performance.

[0102] The samples of Embodiment 7 and Comparative Example 7 doped with magnesium, manganese, and cobalt are tested at 25° C., with lithium nickelate as a substrate, for the capacity at a charge-discharge voltage of 2.8-4.25 V and a charge rate of 0.1 C at 25° C. and the cycle performance at a charge-discharge rate of 1.0 C for 100 cycles. The cycle calculation starts from the 3rd cycle, and the 100-cycle capacity retention is determined by dividing the specific discharge capacity of the 102nd cycle by the specific discharge capacity of the 3rd cycle. The charge and discharge test results of the assembled button batteries of Embodiment 7 and Comparative Example 7 are as shown in Table 6 below.

TABLE-US-00006 Example No. Doping elements in bulk phase Pre-lithiation solution Weight ratio of N or N′ 3.0-4.55 V/0.1 C, First discharge capacity (mAh/g) 3.0-4.65 V/0.5 C, 50-cycle retention Embodiment 7 Mg, Mn, Co Naphthalene boric acid-lithium-Me N7 = 4.5% 216 78% Comparative Example 7 Mg, Mn, Co Lithium-Me N7′ = 4.5% 208 55%

[0103] From the results of Embodiment 7 and Comparative Example 7, it can be seen that the capacity and cycle performance are both improved after pretreatment.

[0104] A detailed introduction to a pre-lithiated lithium ion positive electrode material provided by the disclosure, a preparation method therefor and use thereof according to the disclosure is provided above. The principles and implementations of the disclosure are explained by way of specific embodiments herein. The above embodiments are only provided to facilitate the understanding of the method of the disclosure and core concepts thereof, including the best mode, and also enables any person skilled in the art to practice the disclosure, including manufacturing and using any device or system, and implementing any combined method. It should be noted that several improvements and modifications may be made by an ordinary person skilled in the art without departing from the principles of the present disclosure, and that such improvements and modifications also fall within the protection scope of the appended claims of the present disclosure. The scope of patent protection of the disclosure is defined by the claims, and other embodiments conceivable by those skilled in the art may be included. If these other embodiments have structural elements that are not different from the literal expressions of the claims, or if they include equivalent structural elements that are not substantially different from the literal expressions of the claims, these other embodiments should also be included within the scope of the claims.