Chemical pre-lithiation method of graphite electrodes for lithium-ion batteries

A lithium-ion battery and graphite electrode technology, applied in battery electrodes, electrochemical generators, graphite, etc., can solve the problems of affecting the first-week efficiency of the full battery, affecting the energy density of lithium-ion batteries, and low first-week efficiency, so as to promote Energy density and cycle stability, controllable lithiation depth, and improved efficiency

Active Publication Date: 2022-03-25
EVE ENERGY CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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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 of graphite electrodes for lithium-ion batteries
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  • Chemical pre-lithiation method of graphite electrodes for lithium-ion batteries

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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 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 faster ...

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, comprising the following steps: dissolving a lithiation reagent containing anion radicals in a monobasic ether to obtain a lithiation reagent solution with a concentration of 0.001-10mol / L; preparing A good lithium-ion battery graphite negative electrode sheet is contacted with the lithiation reagent solution for 1s-48h, and the pre-lithiated graphite electrode is obtained after washing and drying. The present invention selects free radical anion lithiation reagents with mild properties to chemically pre-lithiate graphite negative electrode materials of lithium ion batteries in a relatively safe chemical environment, thereby improving the first-cycle efficiency of graphite electrodes and further increasing the energy density of the full battery. Moreover, the monovalent ether solvent used is compatible with the graphite negative electrode, and there will be no phenomena such as co-intercalation or peeling that damage its electrochemical performance; the solution system has strong reducibility, and the lithiation process is fast, and will not affect the electrochemical performance of the electrode.

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 Patents(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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