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Low-concentration lithium salt electrolyte and lithium secondary battery containing same

A lithium secondary battery and electrolyte technology, applied in secondary batteries, non-aqueous electrolyte batteries, secondary battery repair/maintenance, etc., can solve problems such as cycle performance degradation, reduce reduction and decomposition, and inhibit lithium dendrites The effect of forming and reducing the amount of lithium salt

Active Publication Date: 2019-06-25
HEFEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

By forming a stable SEI film on the surface of the negative electrode, it improves the problem of cycle performance degradation caused by the instability of the negative electrode interface film of conventional lithium-ion batteries, effectively inhibits the reduction and decomposition of the electrolyte, and is also effective when using lithium metal negative electrodes. Can inhibit the formation of lithium dendrites and improve the safety of batteries

Method used

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  • Low-concentration lithium salt electrolyte and lithium secondary battery containing same
  • Low-concentration lithium salt electrolyte and lithium secondary battery containing same
  • Low-concentration lithium salt electrolyte and lithium secondary battery containing same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] 1) Preparation of composite low-concentration lithium salt electrolyte:

[0030] The electrolyte solution is prepared in a glove box with water and oxygen content less than 0.1ppm, and the temperature is room temperature. Mix ethylene carbonate (EC) and diethyl carbonate (DEC) in a mass ratio of 3:7, seal it and put it in the refrigerator until it is cooled to -10°C, transfer it to a glove box, add LiFOP (lithium salt ( Ⅰ)) and LiAsF 6 (lithium salt (II)) to make the concentration of LiFOP 0.1mol / L, and make LiAsF 6 The concentration of the mixture is 0.4mol / L, and it is left to stand for 24 hours after being fully mixed.

[0031] 2) Preparation of electrode sheets:

[0032] Positive electrode: the positive active material LiFePO 4 , binder PVDF, and conductive agent SP are mixed according to the mass ratio of 8:1:1, N-methylpyrrolidone is added, stirred in a high-speed vibrating ball mill until stable and uniform, and the positive electrode slurry is obtained; the ...

Embodiment 2～8 and comparative example 1～4

[0042] The composition of the electrolyte and the electrodes used are shown in Table 1. The specifications of the lithium metal negative electrode used are 15.6 mm in diameter and 0.45 mm in thickness, and the EMC and DMC are ethyl methyl carbonate and dimethyl carbonate, respectively. Test method is the same as embodiment 1.

[0043] Table 1: Electrolyte composition and electrode selection of Examples 1-8 and Comparative Examples 1-4. Wherein EMC and DMC are ethyl methyl carbonate and dimethyl carbonate respectively.

[0044]

[0045] The electrolytes of Examples 1-3 and Comparative Examples 1-2 were tested for liquid absorption rate and contact angle, and the test results are shown in Table 2.

[0046] The above batteries were tested for cycle performance at room temperature (25°C), and the test results are shown in Table 3.

[0047] Carry out rate performance test to embodiment 1~3 and comparative example 1~2, test result sees figure 1 .

[0048] Carry out the 1C cy...

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Abstract

The invention provides electrolyte solution containing low-concentration lithium salt and a lithium secondary battery containing the electrolyte solution. The electrolyte contains lithium salt (I), lithium salt (II) and a solvent, wherein the lithium salt (I) is selected from one of lithium bis(oxalato)borate, lithium tetrafluoxalato phosphate, 2-trifluoromethyl-4,5-dicyanoimidazole lithium, lithium difluorooxalatoborate, lithium chlorotrifluoroborate, and lithium trioxalatoborate or more; the lithium salt (II) is selected from one of lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium tetrafluoroborate, lithium perchlorate, LiCF3SO3 and LiN (CxF2x + 1SO2) (CyF2y + 1SO2) or more, wherein x and y are each independently an integer of 0-5, and the total concentration of the lithium salt (I) and the lithium salt (II) is 0.3-0.6 mol / L.

Description

technical field [0001] The present invention relates to the technical field of lithium batteries, in particular to a lithium secondary battery electrolyte containing low-concentration lithium salts, and a lithium secondary battery containing the electrolyte. Background technique [0002] Lithium-ion batteries are widely used in electric vehicles and consumer electronics due to their advantages such as high energy density, high output power, long cycle life, no memory effect and low environmental pollution. With the rapid development of the lithium-ion battery market, people hope that lithium-ion batteries have better electrochemical performance, higher energy density and power density. This is especially true for batteries used in portable devices, electric vehicles and energy storage systems in smart grids. Lithium-ion battery electrolyte, as the carrier of positive and negative ions, has an important impact on the stability of the battery. The main components of the curre...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/0568H01M10/052H01M10/0525H01M10/42
CPCY02E60/10
Inventor 项宏发郑浩孙毅梁鑫
Owner HEFEI UNIV OF TECH
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