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Electrolyte for lithium ion battery, preparation method thereof, and lithium ion battery including electrolyte

A lithium-ion battery and electrolyte technology, applied in the field of lithium-ion batteries, can solve the problems of cycle performance degradation, impact on battery use, obstacles to the development of high-energy-density lithium-ion batteries, etc., and achieve the effect of reducing oxidative decomposition and improving cycle performance.

Active Publication Date: 2019-07-02
HEFEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When the charging voltage of the conventional electrolyte is higher than or equal to 4.4V, the electrolyte will undergo obvious oxidation and decomposition, resulting in rapid attenuation of cycle performance, affecting the use of the battery, and hindering the development of high energy density lithium-ion batteries.

Method used

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  • Electrolyte for lithium ion battery, preparation method thereof, and lithium ion battery including electrolyte
  • Electrolyte for lithium ion battery, preparation method thereof, and lithium ion battery including electrolyte
  • Electrolyte for lithium ion battery, preparation method thereof, and lithium ion battery including electrolyte

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] 1) Electrolyte configuration

[0027] In a glove box protected by an inert gas (wherein the water content is less than 0.1ppm, and the oxygen content is less than 0.1ppm), the lithium-ion battery electrolyte is prepared. The treated EC-DEC was mixed in a mass ratio of 1:1, and then a certain amount of lithium hexafluorophosphate (LiPF 6 ), making LiPF 6 The final concentration is 1mol / L. Divide the above electrolyte into ten parts, nine of which are added with 5- Amino-4-cyano-3-(2-ethoxy-2-carboxymethyl)-2-thiophenecarboxylic acid ethyl ester (TAEC) was shaken until it was completely dissolved, and the other part was added without additives to obtain 1.0M LiPF 6 / EC-DEC(1:1, wt%), 1.0M LiPF 6 / EC-DEC(1:1,wt%)+0.03wt% ethyl 5-amino-4-cyano-3-(2-ethoxy-2-carboxymethyl)-2-thiophenecarboxylate, 1.0 M LiPF 6 / EC-DEC(1:1,wt%)+0.1wt% ethyl 5-amino-4-cyano-3-(2-ethoxy-2-carboxymethyl)-2-thiophenecarboxylate, 1.0 M LiPF 6 / EC-DEC(1:1,wt%)+0.2wt% ethyl 5-amino-4-cyano-3...

Embodiment 2

[0035] Repeat Example 1 with the difference that step 2) the active material is LiCoO 2 , the conductive agent is conductive carbon black (Super P, Timcal Ltd.), the binder is polyvinylidene fluoride (PVDF, HSV 900, Arkema), the dispersant is N-methyl-2-pyrrolidone (NMP), according to LiCoO 2 : Super P: PVDF=84:8:8 mass ratio paste, coated on aluminum foil, then dried, rolled, punched, made into electrode sheet, the active material LiCoO on the electrode surface 2 Controlled at 5mg / cm 2 .

[0036] Prepare the negative electrode whose active material is MAG10 graphite (Hitachi Powdered Metals Co.Ltd.), the binder is PVDF, and the dispersant is N-methyl-2-pyrrolidone (NMP), according to the mass ratio of MAG10:PVDF=92:8 The slurry is coated on the copper foil, and then dried, rolled and punched to make an electrode sheet. The active material MAG10 on the electrode surface is controlled at 2.5mg / cm 2 .

[0037] Fabricate coin cell full cells in an argon-filled glove box. The...

Embodiment 3

[0042] Repeat Example 1, the difference is that the electrolyte solution prepared in step 1) is 1.0M LiPF 6 / EC-DEC-EMC(3:3:4,wt%)+0.3wt% 5-amino-4-cyano-3-(2-ethoxy-2-carboxymethyl)-2-thiophenecarboxylic acid ethyl Esters, 1.0MLiPF 6 / EC-DEC-EMC (3:3:4, wt%). The discharge capacity and capacity retention rate after the electrochemical test are shown in Table 3 below.

[0043] table 3

[0044] Additive content First discharge capacity (mAh g -1 )

[0045] By comparing the results, it is found that compared with the lithium-ion battery using the electrolyte without adding additives, adding 0.3wt% of 5-amino-4-cyano-3-(2-ethoxy-2-carboxymethyl)- The capacity retention rate of the lithium-ion battery with the electrolyte of ethyl 2-thiophenecarboxylate increased from 30% to 82% after 100 cycles. The capacity retention rate of the high-voltage positive electrode material is the highest under the addition of 0.3wt%, and the cycle is also the most stable.

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Abstract

The invention provides an electrolyte for a lithium ion battery, a preparation method thereof, and a lithium ion battery including the electrolyte. The electrolyte of the lithium ion battery includesa lithium salt, an organic solvent, and an additive having the following structure. By means of the electrolyte, the additive preferentially forms an interface film having a uniform thickness on the surface of a positive electrode during charging, protects the surface of the positive electrode material, reduces oxidative decomposition caused by direct contact between the electrolyte and the surface of the positive electrode, maintains the structure of the positive electrode material, and improves the cycle performance of the battery at high voltage.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, in particular to a lithium ion battery electrolyte, and also to a high-voltage lithium ion battery containing the electrolyte. Background technique [0002] Lithium-ion batteries are widely used in portable electronic devices due to their high energy density, high voltage, long life, no memory effect, and no pollution. It is an effective way to develop high-energy-density lithium-ion batteries by developing high-voltage cathode materials and obtaining higher energy output by increasing the cut-off voltage of the battery. However, under high voltage, the high potential on the positive electrode side will cause the conventional electrolyte to continuously oxidize and decompose, resulting in an interfacial film with uneven thickness and high impedance, and side reactions occur on the surface of the positive electrode, causing gas to be produced on the positive electrode side of the bat...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/0567H01M10/0525
CPCH01M10/0525H01M10/0567H01M2300/0025Y02E60/10
Inventor 项宏发郑逸孙毅梁鑫
Owner HEFEI UNIV OF TECH