Reversible over-charge protective electrolyte additive of lithium ion battery and its making method

A technology of electrolyte additive and lithium ion battery, applied in the field of electrolyte additive

Inactive Publication Date: 2008-03-19
WUHAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The present invention proposes a lithium-ion battery reversible overcharge protection electrolyte additive and a preparation method thereof. The purpose is to establish an overcharge protection mechanism inside the lithium-ion battery, which has a reversible overcharge protection function, and the battery can be repeatedly overcharged. Lithium-ion battery overcharge safety issues

Method used

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  • Reversible over-charge protective electrolyte additive of lithium ion battery and its making method

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] Diphenylamine was used as an electrolyte additive, and the battery used was a 103050 lithium-ion battery without liquid injection. Its cathode is LiFePO 4 , the negative electrode is graphite, and the electrolyte is 1mol / LLiPF dissolved with 5% (mass ratio) diphenylamine 6 / EC+DMC (volume ratio 1:1) solution.

[0013] After the battery was vacuum-dried at 85° C. for 24 hours, it was transferred to a dry glove box. Inject 3.5 ml of the above-mentioned electrolyte solution into the battery by means of vacuum pressure injection. After sealing, use 50mA current to form, and then repeat the electric overcharge test. The overcharge current is 100mA, 200mA, 300mA, 500mA respectively, and the overcharge degree is 100% of the battery capacity.

[0014] Experiments have found that when the battery is overcharged at the above-mentioned currents, there is a voltage plateau that does not rise with the increase of the overcharge degree. The voltage platforms at 100mA, 200mA, 300...

Embodiment 2

[0016] O-nitrodiphenylamine is used as the electrolyte additive, and the battery used is Li / LiFePO 4 Button batteries. Among them, the cathode is LiFePO 4 , the negative electrode is a lithium sheet, and the electrolyte is 1moi / L LiPF dissolved with 3% (mass ratio) o-nitrodiphenylamine 6 / EC+DMC (volume ratio 1:1) solution.

[0017] When the battery is charged and discharged at a constant current of 20mA / g, the charging voltage does not continue to rise with the progress of overcharging, but a stable voltage plateau appears at around 3.75V, which clearly shows the effect of additives on the overcharging voltage. Clamp function. After repeated charge and discharge cycles for 50 weeks, the battery overcharge platform has not changed significantly, and the battery capacity has remained basically stable. It shows that the additive can provide long-term and effective reversible overcharge protection for the battery.

Embodiment 3

[0019] Diphenylamine and triphenylamine were used as electrolyte additives, and the battery used was a 103050 lithium-ion battery without liquid injection. Its cathode is LiFePO 4 , the negative electrode is graphite, and the electrolyte is 1mol / L LiPF dissolved in 5% (mass ratio) diphenylamine and 2% (mass ratio) triphenylamine 6 / EC+DMC (volume ratio 1:1) solution.

[0020] After the battery was vacuum-dried at 85° C. for 24 hours, it was transferred to a dry glove box. Inject 3.5 ml of the above-mentioned electrolyte solution into the battery by means of vacuum pressure injection. After sealing, use 50mA current to form, and then repeat the electric overcharge test. Charge and discharge at a constant current of 500mA, and the degree of overcharge is 100% of the battery capacity. With the progress of overcharging, the charging voltage did not continue to rise, but a stable voltage plateau appeared at around 3.7V, which clearly showed the clamping effect of the additive o...

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Abstract

The invention provides a reversible overcharge protective electrolyte additive for a lithium battery and a preparation method thereof. The invention is characterized in that the additive contains at least one aromatic compound selected from amino-benzene, diphenylamine, triphenylamine, pyrrole, thiophene, phenylene sulfide and benzene, or at least one derivative thereof, the mass percentage of the additive in the electrolyte is in a range from 0.3 percent to 20 percent. An auxiliary solvent made of methylbenzene, dimethylbenzene, carbon tetrachloride or chloroform, in a volume less than 20 percent of the electrolyte, is added into the common electrolyte, to increase the dissolvability of the additive molecule in the electrolyte. Then the electrolyte additive is added. The additive molecule can rapidly undergo polymerization at a certain electric potential and form a polymer bridge between the anode and the cathode, and the electronic conductivity of the polymer bridge can reversibly change between insulation state and conduction state along with the voltage variation of the anode, thereby providing the battery with reversible overcharge protection.

Description

technical field [0001] The invention relates to an electrolyte additive capable of providing reversible overcharge protection for batteries, which is suitable for lithium-ion batteries with overcharge safety hazards and belongs to the technical field of chemical power sources. Background technique [0002] The safety of the battery in the overcharged state has always been the biggest application problem faced by the organic electrolyte secondary battery. The unsafe behavior of overcharging of lithium-ion batteries mainly comes from the organic solution electrolyte used in it. For an aqueous solution secondary battery, when it is in an overcharged state, water is oxidized at the positive electrode of the battery to generate oxygen, and reduced at the negative electrode to generate hydrogen, and the resulting gas product can reversibly recombine into water inside the battery. This reversible decomposition-recombination of water provides an internal overcharge protection mecha...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/40H01M6/16H01M10/056H01M10/0567
CPCY02E60/122Y02E60/10
Inventor 艾新平李素丽冯金奎杨汉西曹余良
Owner WUHAN UNIV
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