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Electrolyte for the lithium ion battery

A lithium-ion battery and electrolyte technology, applied in secondary batteries, non-aqueous electrolyte batteries, organic electrolyte batteries, etc., can solve the problems of high production cost of fluorophosphate ester, low flame retardant efficiency of additives, limited flame retardant efficiency, etc. question

Inactive Publication Date: 2007-08-15
UNIV OF SCI & TECH OF CHINA +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] U.S. Patent United States Patent 6,455,200 uses hexamethoxyphosphazene as a flame retardant additive for lithium-ion battery electrolytes. This additive has little effect on the battery performance of lithium-ion batteries, but the flame retardant efficiency of this additive is low
United States Patent 6,924,061 synthesizes fluorophosphates to prepare flame-retardant electrolytes. This type of additive has good flame-retardant efficiency and does not damage battery performance, but the production cost of such fluorophosphates is relatively high.
US patent UnitedStates Patent 7,026,074 uses a series of self-made aryl phosphates as flame retardant additives for lithium-ion battery electrolytes. This type of additive has little effect on battery performance, but the flame retardant efficiency of this type of additive is limited, and it is difficult to achieve complete non-combustibility
[0004] X.M.Wang (J.Electrochem.Soc., 2001, (148): A1058) used trimethyl phosphate (TMP) as a flame retardant, studied the combustion performance and electrochemical stability of the TMP-containing electrolyte, and found that TMP itself has Good flame retardant effect and oxidation stability, but poor reduction stability
Yao (J.Power Source, 2005, (144): 170) found that trimethyl phosphite can be used as a flame retardant additive for lithium-ion battery electrolyte, and trimethyl phosphite has a certain flame retardant effect, and at the same time Trimethyl phosphate can improve the interface properties between the positive electrode and the electrolyte, but has poor compatibility with the graphite negative electrode

Method used

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  • Electrolyte for the lithium ion battery
  • Electrolyte for the lithium ion battery
  • Electrolyte for the lithium ion battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Dissolve 5.45g ethylene carbonate (EC) in 5.45g diethyl carbonate (DEC) and add 1.52g LiPF 6 1M LiPF 6 +EC / DEC (1:1wt) solution, and as a reference electrolyte, add 5wt% or 0.62g methyl methylphosphonate (DMMP) and 2wt% or 0.25g vinyl ethylene carbonate (VEC) , to obtain a flame retardant electrolyte.

[0035] Graphite was used as the negative electrode, lithium sheet was used as the counter electrode, and Celgard2400 was used as the separator to assemble the negative electrode half-cell. Figure 1 is the curve obtained from the cyclic voltammetry test. The reduction peak at 1.2-1.0V in the figure is the reduction of VEC to form a film, which protects the graphite electrode and prevents the peeling of the graphite structure caused by DMMP.

[0036]Using graphite as the anode, LiCoO 2 As the positive electrode, Celgard2400 as the separator, assembled into a full battery. at 0.2mA / cm 2 The capacity-voltage curve obtained by charging and discharging three times at a c...

Embodiment 2

[0038] With the 1M LiPF that makes in embodiment 1 6 +EC / DEC (1:1wt) solution was used as a reference electrolyte, and 10 wt%, ie, 1.24g DMMP was added to prepare a flame-retardant electrolyte. Using MCMB as the anode, LiCoO 2 As the positive electrode, Celgard2400 as the separator, assembled into a full battery. Fig. 3 is the cycle performance curve of the full battery containing the reference electrolyte and the flame-retardant electrolyte. The performance of comparative benchmark electrolyte and flame retardant electrolyte is shown in the table below:

[0039] First discharge capacity

Embodiment 3

[0041] Mix 2.30gDMMP, 1.15gEC and 1.15gDEC, add 0.608gLiPF to the mixed solvent 6 , dubbed 1M LiPF 6 +DMMP / EC / DEC (2:1:1wt) electrolyte. Using LiCoO 2 As the positive electrode, a lithium sheet is used as the counter electrode, and Celgard3501 is used as the diaphragm to assemble the positive electrode half-cell. The discharge capacity-cycle number curve of the constant current charge and discharge test is shown in Figure 4, and the positive half-cell performance of the flame-retardant electrolyte and the reference electrolyte in Example 4 is shown in the following table:

[0042] First discharge capacity

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Abstract

The related non-aqueous electrolyte with flame-proof function for Li-ion cell is prepared by adding 1-100wt% (1-30% better) alkylphosphate (methyl-dimethylphosphonate) as the fire-retardant additive based on current product. When adding 5% the methyl-dimethylphosphonate, the electrolyte can reduce its self-extinguishing time obviously, and can achieve up non-combustible state when the addition quantity up to 10%.

Description

technical field [0001] The invention relates to an electrolyte solution for a lithium ion battery. More specifically, the present invention relates to a non-aqueous electrolytic solution having a flame-retardant function. Background technique [0002] Due to the advantages of high energy density, high output voltage, long cycle life, and no environmental pollution, lithium-ion batteries have extremely important applications in electronic products, electric vehicles, aerospace and other fields. However, the current lithium-ion battery electrolyte is composed of flammable organic solvents and lithium salts. These organic solvents and their vapors are easy to catch fire and cause fires or even explosions, which directly lead to safety issues for lithium-ion batteries. Therefore, the use of flame-retardant or even non-flammable electrolytes has important practical significance for solving the safety problems of lithium-ion batteries. [0003] United States Patent 6,455,200 use...

Claims

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Application Information

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IPC IPC(8): H01M10/40H01M6/16C09K21/06H01M10/056H01M10/0567
CPCY02E60/122Y02E60/10
Inventor 陈春华项宏发张承平
Owner UNIV OF SCI & TECH OF CHINA
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