Electrolyte containing solid particles and lithium ion secondary battery

Abstract

Disclosed is an electrolyte containing solid particles and lithium ion secondary battery, comprising: an organic solvent, an electrolyte lithium salt, and glass particles dispersed in the liquid electrolyte, and the glass refers to composite oxide glass containing a lithium oxide and a phosphorus oxide. The above technical scheme may effectively improve the safety performance of a battery, and prolong the service life of the battery.

Claims

1. An electrolyte containing solid particles, comprising: an organic solvent, an electrolyte lithium salt and glass particles dispersed in the liquid electrolyte, and the glass is composite oxide glass comprising a lithium oxide and a phosphorus oxide.

2. The electrolyte containing the solid particles according to claim 1, wherein the composite oxide glass comprising the lithium oxide and the phosphorus oxide is xLi.sub.2O-(1-x)P.sub.2O.sub.5 glass, wherein 0.3≤x≤0.7.

3. The electrolyte containing the solid particles according to claim 1, wherein the composite oxide glass comprising the lithium oxide and the phosphorus oxide is M-doped xLi.sub.2O-(1-x)P.sub.2O.sub.5 glass, wherein 0.3≤x≤0.7, M is selected from one or more of the group consisting of sulfur, boron, sodium, potassium, halogen, silicon, niobium and tantalum.

4. The electrolyte containing the solid particles according to claim 3, wherein the molar percentage content of M in the glass is less than or equal to 10%.

5. The electrolyte containing the solid particles according to claim 1, wherein further comprising a functional additive, the functional additive is selected from one or more of the group consisting of vinylene carbonate, fluoroethylene carbonate, ethylene sulfate, methylene methane disulfonate, 1,3-propane sultone, 1,4-butane sultone, 1,3-propene sultone, lithium difluorophosphate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium difluorobisoxalate phosphate, lithium tetrafluoromonooxalate phosphate, lithium bis(trifluoromethane sulfonimide) and lithium bis(fluorosulfonyl)imide.

6. The electrolyte containing the solid particles according to claim 1, wherein further comprising a suspension aid, the suspension aid is selected from one or more of the group consisting of a polymer dispersant, a surfactant and an anti-settling agent.

7. The electrolyte containing the solid particles according to claim 1, wherein the organic solvent is selected from one or more of the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

8. The electrolyte containing the solid particles according to claim 1, wherein the electrolyte lithium salt is selected from one or more of the group consisting of lithium hexafluorophosphate, lithium bis(trifluoromethane sulfonimide) and lithium bis(fluorosulfonyl)imide.

9. The electrolyte containing the solid particles according to claim 1, wherein the particle size of the glass particles dispersed in the liquid electrolyte is 0.01-2 microns.

10. The electrolyte containing the solid particles according to claim 9, wherein the particle size of the glass particles dispersed in the liquid electrolyte is 0.05-1 micron.

11. The electrolyte containing the solid particles according to claim 1, wherein the mass concentration of the glass particles in the electrolyte is 0.01%-30%.

12. A lithium ion secondary battery, comprising the electrolyte containing the solid particles according to claim 1.

13. The electrolyte containing the solid particles according to claim 2, wherein the organic solvent is selected from one or more of the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

14. The electrolyte containing the solid particles according to claim 3, wherein the organic solvent is selected from one or more of the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

15. The electrolyte containing the solid particles according to claim 2, wherein the electrolyte lithium salt is selected from one or more of the group consisting of lithium hexafluorophosphate, lithium bis(trifluoromethane sulfonimide) and lithium bis(fluorosulfonyl)imide.

16. The electrolyte containing the solid particles according to claim 3, wherein the electrolyte lithium salt is selected from one or more of the group consisting of lithium hexafluorophosphate, lithium bis(trifluoromethane sulfonimide) and lithium bis(fluorosulfonyl)imide.

17. The electrolyte containing the solid particles according to claim 2, wherein the particle size of the glass particles dispersed in the liquid electrolyte is 0.01-2 microns.

18. The electrolyte containing the solid particles according to claim 3, wherein the particle size of the glass particles dispersed in the liquid electrolyte is 0.01-2 microns.

19. The electrolyte containing the solid particles according to claim 2, wherein the mass concentration of the glass particles in the electrolyte is 0.01%-30%.

20. The electrolyte containing the solid particles according to claim 3, wherein the mass concentration of the glass particles in the electrolyte is 0.01%-30%.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The following specific embodiments describe the present disclosure in detail, but the present disclosure is not limited to the following embodiments.

Embodiment 1

[0022] Preparation of Non-Aqueous Suspension Electrolyte:

[0023] In an argon-filled glove box (oxygen content <1 ppm, and water content <1 ppm), 59.9 g of ethyl methyl carbonate (EMC) was mixed with 26.6 g of ethylene carbonate (EC), and 13.5 g of lithium hexafluorophosphate was continuously added to solution mixed uniformly, a basic electrolyte was obtained after stirring and dissolving, and it was cooled to a room temperature. 0.5Li.sub.2O-0.5P.sub.2O.sub.5(D50 was 0.2 micron) was added to the above basic electrolyte according to a weight part of 5%, it was stirred at a high speed for 10 minutes, then taken out from the glove box after sealing, ultrasonic treatment (frequency: 50 Hz) was performed by using an ultrasonic cleaner, and a suspension electrolyte was obtained after 30 minutes, and put into the glove box after sealing.

[0024] Battery Preparation:

[0025] Main parameters of positive electrode: calculated by the mass fraction, a positive electrode active material LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 is 95%, a binder is 3%, a conductive carbon black is 2%, and an aluminum foil was used as a current collector; main parameters of negative electrode: a negative electrode active material was 96% of an artificial graphite, the binder was 3%, the conductive carbon black was 1%, and a copper foil was used as a current collector; and a polypropylene (PP) diaphragm was used, to prepare a dry battery cell by coating, laminating and packaging processes. The above dry battery cell dried was put into the argon-filled glove box, to ensure that the above suspension electrolyte was still in a stable suspension state, 10 g of the suspension electrolyte was injected into the dry battery cell with a needle, it was taken out after sealing and stands for 24 hours, and after subsequent formation, aging and capacity separation, a soft-pack lithium ion secondary battery was obtained. The battery capacity was 2700 mAh, and the battery energy density was about 270 Wh/kg. The battery after the capacity separation was subjected to high-temperature cycling, storage performance and hot box tests respectively.

[0026] Battery Performance Test:

[0027] (1) Battery cycle life test: under the ambient temperature of 45° C., the above soft-pack lithium ion secondary battery was charged and discharged in the voltage range of 2.50 V˜4.20 V, the charge and discharge rates were both 1C, the charge-discharge cycle stability thereof under a high-temperature condition was investigated.

[0028] (2) 70° C. high-temperature shelving experiment it was charged at a room temperature and 1C to 4.2 V, and continuously charged at a constant voltage, a cut-off current was 0.05C, the battery volume was tested under a condition of 25° C. after the battery was fully charged, it was placed in a 70° C. oven after the test was completed, and after 7 days, the volume and the capacity retention rate and recovery rate of the soft-pack battery were tested.

[0029] (3) Hot box test: it was charged at a room temperature and 1C to 4.2 V, and continuously charged at a constant voltage, a cut-off current was 0.05C, the battery was placed in a hot box after it was fully charged, the room temperature was raised to 150° C., the temperature was kept for 2 h, and then the temperature was continuously raised to 200° C. at a rate of 2° C./min, the temperature was kept for 0.5 h, and it was observed whether the battery cell catches fire or explodes in this process.

Embodiment 2

[0030] In a basic electrolyte, 5% of 0.5Li.sub.2O-0.5P.sub.2O.sub.5(D50 was 0.2 micron) was added, and 0.3% of dispersant ACUMER 1000 (purchased from Shanghai Kaiyin Chemical Co., Ltd.) was added, to prepare the suspension electrolyte by ultrasonic dispersion. Battery preparation and performance tests were the same as in Embodiment 1.

Embodiment 3

[0031] In a basic electrolyte, 10% of 0.5Li.sub.2O-0.5P.sub.2O.sub.5(D50 was 0.2 micron) was added, and 0.5% of dispersant ACUMER 1000 was added, to prepare the suspension electrolyte by ultrasonic dispersion. Battery preparation and performance tests were the same as in Embodiment 1.

Embodiment 4

[0032] In a basic electrolyte, 5% of 0.5Li.sub.2O-0.5P.sub.2O.sub.5(D50 was 1 micron) was added, and 0.5% of dispersant ACUMER 1000 was added, to prepare the suspension electrolyte by ultrasonic dispersion. Battery preparation and performance tests were the same as in Embodiment 1.

Embodiment 5

[0033] In a basic electrolyte, 5% of 0.5Li.sub.2O-0.5P.sub.2O.sub.5(D50 was 0.05 micron) was added, and 0.1% of dispersant ACUMER 1000 was added, to prepare the suspension electrolyte by ultrasonic dispersion. Battery preparation and performance tests were the same as in Embodiment 1.

Embodiment 6

[0034] In a basic electrolyte, 1% of 0.5Li.sub.2O-0.5P.sub.2O.sub.5(D50 was 0.2 micron) was added, and 0.1% of dispersant ACUMER 1000 was added, to prepare the suspension electrolyte by ultrasonic dispersion. Battery preparation and performance tests were the same as in Embodiment 1.

Embodiment 7

[0035] In a basic electrolyte, 15% of 0.5Li.sub.2O-0.5P.sub.2O (D50 was 0.2 micron) was added, and 0.6% of dispersant ACUMER 1000 was added, to prepare the suspension electrolyte by ultrasonic dispersion. Battery preparation and performance tests were the same as in Embodiment 1.

Embodiment 8

[0036] In a basic electrolyte, 5% of 0.3Li.sub.2O-0.7P.sub.2O.sub.5(D50 was 0.2 micron) was added, and 0.3% of dispersant ACUMER 1000 was added, to prepare the suspension electrolyte by ultrasound. Battery preparation and performance tests were the same as in Embodiment 1.

Embodiment 9

[0037] In a basic electrolyte, 5% of 0.6Li.sub.2O-0.4P.sub.2O.sub.5(D50 was 0.2 micron) was added, and 0.3% of dispersant ACUMER 1000 was added, to prepare the suspension electrolyte by ultrasound. Battery preparation and performance tests were the same as in Embodiment 1.

Contrast Example 1

[0038] A basic electrolyte was obtained by the same method as in Embodiment 1 as a comparison, without adding any additives.

Contrast Example 2

[0039] In a basic electrolyte, 50% of 0.5Li.sub.2O-0.5P.sub.2O.sub.5(D50 was 0.2 micron) was added, and 2% of dispersant ACUMER 1000 was added, to prepare the suspension electrolyte by ultrasound. Battery preparation and performance tests are the same as in Embodiment 1.

Contrast Example 3

[0040] In a basic electrolyte, 5% of 0.5Li.sub.2O-0.5P.sub.2O.sub.5(D50 was 5 microns) was added, and 0.5% of dispersant ACUMER 1000 was added, to prepare the suspension electrolyte by ultrasound, but the suspension may appear apparent settlement within a few minutes, and was not injected into a battery cell for subsequent testing.

[0041] Combined with Embodiments 1-9 and Contrast examples 1-3, it may be seen that the battery using the suspension electrolyte containing xLi.sub.2O-(1-x)P.sub.2O.sub.5 glass particles has the better high-temperature cycle life and high-temperature storage performance, and may inhibit gas generation of the battery cell under a high-temperature storage condition. At the same time, it may be seen that the addition of a small amount of the dispersant in the electrolyte has no significant effect on the performance. The excessive addition or the use of xLi.sub.2O-(1-x)P.sub.2O.sub.5 glass particles with the large particle size may lead to the significant deterioration of the battery cell performance or the deterioration of the electrolyte suspension stability so that the setting was generated.

TABLE-US-00001 TABLE 1 Physical and chemical properties of electrolyte Solid Addition Particle particles proportion size/micron Dispersant Embodiment 0.5Li.sub.2O—0.5P.sub.2O.sub.5 5% 0.2 μm — 1 Embodiment 0.5Li.sub.2O—0.5P.sub.2O.sub.5 5% 0.2 μm ACUMER 2 1000 Embodiment 0.5Li.sub.2O—0.5P.sub.2O.sub.5 10%  0.2 μm ACUMER 3 1000 Embodiment 0.5Li.sub.2O—0.5P.sub.2O.sub.5 5% 1 μm ACUMER 4 1000 Embodiment 0.5Li.sub.2O—0.5P.sub.2O.sub.5 5% 0.05 μm ACUMER 5 1000 Embodiment 0.5Li.sub.2O—0.5P.sub.2O.sub.5 1% 0.2 μm ACUMER 6 1000 Embodiment 0.5Li.sub.2O—0.5P.sub.2O.sub.5 15%  0.2 μm ACUMER 7 1000 Embodiment 0.3Li.sub.2O—0.7P.sub.2O.sub.5 5% 0.2 μm ACUMER 8 1000 Embodiment 0.6Li.sub.2O—0.4P.sub.2O.sub.5 5% 0.2 μm ACUMER 9 1000 Contrast — — 0.2 μm — example 1 Contrast 0.5Li.sub.2O—0.5P.sub.2O.sub.5 50%  0.2 μm ACUMER example 2 1000 Contrast 0.5Li.sub.2O—0.5P.sub.2O.sub.5 5% 5 μm ACUMER example 3 1000

TABLE-US-00002 TABLE 2 Comparison of high-temperature cycle, storage and hot box performance 45° C. Initial 300 Weekly 70° C. 7-day storage capacity capacity Capacity Capacity Volume (Ah) retention rate retention recovery change Hot box test Embodiment 1 2.706 91.6% 87.54% 94.11% 2.3% No fire or explosion Embodiment 2 2.707 90.7% 86.39% 93.15% 2.1% No fire or explosion Embodiment 3 2.712 93.2% 90.21% 96.35% 1.9% No fire or explosion Embodiment 4 2.695 90.9% 85.25% 93.18% 2.3% No fire or explosion Embodiment 5 2.704 92.1% 89.13% 95.7% 1.9% No fire or explosion Embodiment 6 2.682 86.2% 83.34% 89.48% 4.3% No fire or explosion Embodiment 7 2.723 90.8% 89.15% 95.26% 2.1% No fire or explosion Embodiment 8 2.693 89.1% 84.36% 91.24% 1.5% No fire or explosion Embodiment 9 2.713 92.7% 88.34% 95.8% 2.8% No fire or explosion Contrast 2.675 63.2% 68.49% 72.21% 11.7% Fire while heated to example 1 180° C. Contrast 2.693 69.4% 72.68% 78.29% 1.3% No fire or explosion example 2