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Chemical pre-lithiation method for graphite electrode of lithium ion battery

A lithium-ion battery, graphite electrode technology, applied in battery electrodes, electrochemical generators, graphite and other directions, can solve the problems of affecting the energy density of lithium-ion batteries, affecting the first-week efficiency of the full battery, and low first-week efficiency, achieving promotion Energy density and cycle stability, controllable lithiation depth, and improved efficiency

Active Publication Date: 2021-03-12
EVE ENERGY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The present invention aims at the problem that the first-cycle efficiency of the existing commercialized lithium-ion battery is low due to the graphite negative electrode material, which affects the first-cycle efficiency of its matched full battery, thereby affecting the energy density of the lithium-ion battery, and provides a graphite electrode for the lithium-ion battery The chemical pre-lithiation method improves the first cycle efficiency of graphite electrodes, and also provides the possibility for the development of a series of high first cycle efficiency and high energy density battery systems

Method used

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  • Chemical pre-lithiation method for graphite electrode of lithium ion battery
  • Chemical pre-lithiation method for graphite electrode of lithium ion battery
  • Chemical pre-lithiation method for graphite electrode of lithium ion battery

Examples

Experimental program
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Effect test

Embodiment 1

[0030] (1) The methyl propyl ether solution of 0.5mol / L naphthalene lithium of 1mL was reacted with natural graphite electrode (loading is about 2mg, containing graphite 93wt%) under the protection of inert atmosphere for different time (5min, 30min, 1h, 3h). After the reaction was complete, it was washed three times with methyl propyl ether and dried for later use.

[0031] (2) Carry out XRD detection to the above graphite electrodes with different lithiation depths, the scan rate is 4° / min, and the xrd spectrum is as follows figure 1 As shown, with the increase of time, the pre-lithiation depth of the graphite electrode gradually deepens, and it can even be lithiated to the first-order graphite (LiC 6 ).

[0032] (3) Using natural graphite electrodes with different pre-lithiation depths as positive electrodes and lithium metal as negative electrodes, ternary electrolytes (1M LiPF 6 EC / DEC / DMC (v:v:v=1:1:1)) Assemble the half-cell, and conduct a charge-discharge test. Th...

Embodiment 2

[0034] (1) Take 3mL of 0.25mol / L tetramethylbiphenyllithium ethyl butyl ether solution and react with artificial graphite electrode (loading is about 2.5mg, containing graphite 95wt%) for 2 minutes under the protection of inert atmosphere. After the reaction was complete, it was washed three times with dimethyl carbonate and dried for later use.

[0035] (2) The artificial graphite electrode before and after pre-lithiation is used as the positive electrode, and the lithium metal is used as the negative electrode, and the ternary electrolyte (1MLiPF 6 EC / DEC / DMC (v:v:v=1:1:1)) Assemble the half-cell, and conduct a charge-discharge test. The charge and discharge curves and cycle diagrams of the previous two weeks are shown in 3 and Figure 4 As shown, after pre-lithiation, the open-circuit voltage of the half-cell decreased from 3.01V to 0.23V, and the efficiency increased from 84.45% to 98.91% in the first week. Moreover, the artificial graphite after pre-lithiation has faste...

Embodiment 3

[0038] Take 3ml of 0.001mol / L anthracene-lithium propyl amyl ether solution and react with artificial graphite electrode (with a loading of about 2.5mg, containing 95wt% graphite) for 48h under the protection of an inert atmosphere. After the reaction was complete, it was washed three times with tetrahydrofuran and dried for later use.

[0039]The artificial graphite electrode before and after pre-lithiation was used as the positive electrode, and the lithium metal was used as the negative electrode, and the ternary electrolyte (1MLiPF 6 EC / DEC / DMC (v:v:v=1:1:1)) Assemble the half-cell, and conduct a charge-discharge test. After pre-lithiation, the open-circuit voltage of the half-cell decreased from 3.13V to 0.27V, and the efficiency increased from 85.03% to 99.31% in the first week.

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Abstract

The invention discloses a chemical pre-lithiation method for a graphite electrode of a lithium ion battery. The chemical pre-lithiation method comprises the following steps: dissolving a lithiation reagent containing anion free radicals into monobasic ether to obtain a lithiation reagent solution with the concentration of 0.001-10 mol / L; and carrying out contact reaction on the prepared graphite negative plate of the lithium ion battery and a lithiation reagent solution for 1s to 48h, washing and drying to obtain the pre-lithiated graphite electrode. According to the invention, the free radical anion lithiation reagent with mild property is selected, and the graphite negative electrode material of the lithium ion battery is chemically pre-lithiated in a relatively safe chemical environment, so that the first week efficiency of the graphite electrode is improved, and the energy density of the whole battery is further improved. The used monobasic ether solvent is compatible with the graphite negative electrode, so that the phenomenon that the electrochemical performance of the graphite negative electrode is damaged by co-embedding or stripping and the like is avoided; the solution system is high in reducibility, the lithiation process is rapid, and the electrochemical performance of the electrode is not influenced.

Description

technical field [0001] The invention belongs to the technical field of new energy, and in particular relates to a chemical prelithiation method for graphite electrodes of lithium ion batteries. Background technique [0002] Lithium-ion batteries are widely used in 3C and electric vehicles due to their advantages such as high specific energy, high volumetric energy density, low self-discharge performance, and long service life. In the past 20 years, many important breakthroughs have been made in the research of lithium-ion batteries in terms of energy density, cost, safety, etc., and now the energy density of lithium-ion batteries has reached or approached the limit value of existing electrode materials. In the current commercialized lithium-ion batteries, the first-week coulombic efficiency of positive electrodes such as lithium cobalt oxide (LCO) and lithium iron phosphate (LFP) is greater than 95%, which is the source of active lithium ions; while the first-week efficiency...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/04H01M4/583H01M4/62H01M10/0525C01B32/20
CPCH01M4/0404H01M4/583H01M4/625H01M10/0525C01B32/20Y02E60/10
Inventor 艾新平沈弈非曹余良杨汉西钱江锋李惠
Owner EVE ENERGY CO LTD
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