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Electrolyte, construction method of negative electrode interface film and lithium ion battery

A lithium-ion battery and electrolyte technology, applied in the field of lithium-ion batteries, the construction of the negative electrode interface film, and the electrolyte, can solve the problems of poor battery performance, high viscosity, and influence on the construction of the SEI film of lithium batteries, so as to achieve the promotion of transmission rate, Effect of improving electrochemical performance and improving interface properties

Inactive Publication Date: 2019-12-20
SOUTH CHINA NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] If the lithium secondary battery electrolyte contains ethylene carbonate, since the melting point of ethylene carbonate is as high as 39°C, such a high melting point causes the electrolyte system to exhibit high viscosity at low temperature, which affects the construction of SEI film at low temperature. It also affects the transmission rate of lithium ions in the bulk electrolyte and SEI film, which will lead to poor battery performance of lithium batteries at low temperatures

Method used

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  • Electrolyte, construction method of negative electrode interface film and lithium ion battery
  • Electrolyte, construction method of negative electrode interface film and lithium ion battery
  • Electrolyte, construction method of negative electrode interface film and lithium ion battery

Examples

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Embodiment 1

[0033] This embodiment provides a lithium-ion secondary battery and a preparation method thereof, the steps are as follows:

[0034] (1) Preparation of electrolyte

[0035] Mix ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a mass ratio of EC:EMC=1:2 to obtain an organic solvent.

[0036] At room temperature, the conductive lithium salt lithium hexafluorophosphate accounting for 12.5 wt% of the organic solvent was dissolved in the organic solvent, and stirred evenly to obtain a basic electrolyte.

[0037] Dimethyl sulfite is added to the basic electrolyte to obtain an electrolyte, so that the dimethyl sulfite accounts for 0.5 wt% of the electrolyte.

[0038] (2) Preparation of lithium-ion batteries

[0039] Add the above-mentioned electrolyte solution into the graphite / lithium metal half-battery, and after charging and discharging, it becomes a lithium-ion battery, wherein the first charging current is 195mA, and the first discharging current is 390mA.

Embodiment 2

[0041] This embodiment provides a lithium-ion secondary battery and a preparation method thereof, the steps are as follows:

[0042] (1) Preparation of electrolyte

[0043] Mix ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a mass ratio of EC:EMC=1:2 to obtain an organic solvent.

[0044] At room temperature, the conductive lithium salt lithium hexafluorophosphate accounting for 12.5 wt% of the organic solvent was dissolved in the organic solvent, and stirred evenly to obtain a basic electrolyte.

[0045] Dimethyl sulfite is added to the basic electrolyte to obtain an electrolyte, so that the dimethyl sulfite accounts for 1 wt% of the electrolyte.

[0046] (2) Preparation of lithium-ion batteries

[0047] Add the above-mentioned electrolyte solution into the graphite / lithium metal half-battery, and after charging and discharging, it becomes a lithium-ion battery, wherein the first charging current is 195mA, and the first discharging current is 390mA.

Embodiment 3

[0049] This embodiment provides a lithium-ion secondary battery and a preparation method thereof, the steps are as follows:

[0050] (1) Preparation of electrolyte

[0051] Mix ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a mass ratio of EC:EMC=1:2 to obtain an organic solvent.

[0052]At room temperature, the conductive lithium salt lithium hexafluorophosphate accounting for 12.5 wt% of the organic solvent was dissolved in the organic solvent, and stirred evenly to obtain a basic electrolyte.

[0053] Dimethyl sulfite is added to the basic electrolyte to obtain an electrolyte, so that the dimethyl sulfite accounts for 2 wt% of the electrolyte.

[0054] (2) Preparation of lithium-ion batteries

[0055] Add the above-mentioned electrolyte solution into the graphite / lithium metal half-battery, and after charging and discharging, it becomes a lithium-ion battery, wherein the first charging current is 195mA, and the first discharging current is 390mA.

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Abstract

The invention relates to an electrolyte, a construction method of a negative electrode interface film and a lithium ion battery. The electrolyte comprises the following components: dimethyl sulfite, an organic solvent and conductive lithium salts, wherein the organic solvent comprises ethylene carbonate. The electrolyte can construct a stable SEI film on the surface of a graphite negative electrode through at least one charging and discharging process at a low temperature, so that the transmission rate of lithium ions at the low temperature is effectively promoted, the electrode / electrolyte interface property of a lithium secondary battery is improved, and electrochemical performance of the lithium secondary battery at the low temperature is improved.

Description

technical field [0001] The invention relates to the field of lithium batteries, in particular to an electrolyte solution, a construction method of a negative electrode interface film and a lithium ion battery. Background technique [0002] Since its commercialization in the early 1990s, lithium secondary batteries have achieved tremendous development, and have continuously replaced traditional secondary batteries in various fields, such as lead-acid batteries, nickel-cadmium batteries, nickel-hydrogen batteries, etc., and become chemical power sources. The most competitive secondary battery in the field. Compared with other secondary batteries, lithium secondary batteries have the advantages of high working voltage, long cycle life, low self-discharge rate, environmental friendliness, and no memory effect. Lithium secondary battery is mainly composed of positive and negative electrodes, electrolyte and diaphragm. In terms of working principle, it is a concentration battery,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/0569H01M10/0563H01M10/0525
CPCH01M10/0525H01M10/0563H01M10/0569H01M2300/0028H01M2300/0091Y02E60/10
Inventor 李伟善郭如徳车艳霞许梦清廖友好邢丽丹
Owner SOUTH CHINA NORMAL UNIVERSITY