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Lithium ion battery electrolyte suitable for NCM811 and SiO-C material system and preparation method

A lithium-ion battery and electrolyte technology, which is applied in secondary batteries, circuits, electrical components, etc., can solve the problems of inability to form a stable solid-state electrolyte film, low cycle stability, and capacity decay, so as to alleviate the phase transition of materials and metal Effects of ion dissolution, excellent cycle performance, and low orbital energy level

Active Publication Date: 2019-12-20
SHENZHEN BAK POWER BATTERY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The inventor of the present application found in the process of realizing the embodiment of the present application that the existing lithium-ion battery electrolyte has at least the following technical problems: the lithium-ion battery with NCM811 as the positive electrode and SiO-C as the negative electrode, the existing electrolyte and The compatibility of electrode materials is poor. NCM811 is a positive electrode material, which is prone to phase transition and oxygen evolution during the cycle of lithium-ion batteries. NCM811 reacts with the electrolyte and produces gas, which leads to rapid capacity decay and low cycle stability; SiO -C is the negative electrode material. A stable solid electrolyte film cannot be formed on the surface of the material. The electrolyte directly contacts and reacts with the electrode, which leads to the failure of the electrode and the rapid decline in capacity, which leads to further improvement in the cycle performance of the corresponding lithium-ion battery.

Method used

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  • Lithium ion battery electrolyte suitable for NCM811 and SiO-C material system and preparation method

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preparation example Construction

[0036] In a second aspect, the present invention provides a method for preparing a lithium-ion battery electrolyte suitable for NCM811 and SiO-C material systems, comprising the following steps:

[0037] Step 1. In a glove box filled with argon and moisture less than 2 ppm, respectively add ethyl methyl carbonate, diethyl carbonate, and ethylene carbonate into the reaction vessel and stir well to obtain mixed solvent 1;

[0038] Step 2. Slowly add lithium hexafluorophosphate and lithium difluorophosphate into the above-mentioned mixed solvent 1 in a glove box filled with argon gas and the water content is less than 2 ppm, and stir well in the reaction vessel to obtain mixed solution 2;

[0039] Step 3. In a glove box filled with argon and moisture less than 2 ppm, vinylene carbonate, fluoroethylene carbonate, vinyl sulfate, and 1,3-propane sultone were added to the above mixed solution 2 respectively, and the Stir well in the reaction vessel evenly, and transfer it into a stor...

Embodiment 1

[0042] The lithium-ion battery electrolyte suitable for NCM811 and SiO-C material systems is made of the following components in proportion by weight: 86 parts of organic solvent, 13.2 parts of lithium salt and 9.6 parts of additives.

[0043] The organic solvent is composed of ethyl methyl carbonate, diethyl carbonate and ethylene carbonate; the mass ratio of the ethyl methyl carbonate, diethyl carbonate and ethylene carbonate is 42:25:19.

[0044] The lithium salt is composed of lithium hexafluorophosphate and lithium difluorophosphate; the mass ratio of lithium hexafluorophosphate to lithium difluorophosphate is 12:1.2.

[0045] The additive is composed of vinylene carbonate, fluoroethylene carbonate, vinyl sulfate and 1,3-propane sultone; the vinylene carbonate, fluoroethylene carbonate, vinyl sulfate and 1,3 - The mass ratio of propane sultone is 1.1:6:1.3:1.2.

[0046] Wherein, based on the total mass of the SiO—C material, the mass content of SiO is 5%.

[0047] The p...

Embodiment 2

[0052] The lithium-ion battery electrolyte suitable for NCM811 and SiO-C material systems is made of the following components by weight: 76 parts of organic solvent, 16 parts of lithium salt and 8 parts of additives.

[0053] The organic solvent is composed of ethyl methyl carbonate, diethyl carbonate and ethylene carbonate; the mass ratio of the ethyl methyl carbonate, diethyl carbonate and ethylene carbonate is 40:20:16.

[0054] The lithium salt is composed of lithium hexafluorophosphate and lithium difluorophosphate; the mass ratio of lithium hexafluorophosphate to lithium difluorophosphate is 14:2.

[0055] The additive is composed of vinylene carbonate, fluoroethylene carbonate, vinyl sulfate and 1,3-propane sultone; the vinylene carbonate, fluoroethylene carbonate, vinyl sulfate and 1,3 - The mass ratio of propane sultone is 1:5:1:1.

[0056] Wherein, based on the total mass of the SiO—C material, the mass content of SiO is 5%.

[0057] The preparation method of the l...

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Abstract

The invention discloses a lithium ion battery electrolyte suitable for a NCM811 and SiO-C material system and a preparation method. In the electrolyte of the present invention, an organic solvent composed of ethyl methyl carbonate, diethyl carbonate, and ethylene carbonate, a lithium salt composed of lithium hexafluorophosphate and lithium difluorophosphate, and an additive composed of vinylene carbonate, fluoroethylene carbonate, ethylene sulfate, and 1,3-propane sultone are compounded in a certain proportion, and cooperate to react, during a lithium ion battery cycle, on the surface of NCM811 and SiO-C and form a stable solid electrolyte protective film to prevent direct contact between the electrolyte and NCM811 and SiO, thereby reducing the side reactions between the electrode and theelectrolyte, and reducing the phase transition and volume change of the material, and further improving the cycling performance of the lithium ion battery. Experimental results show that by using theelectrolyte of the present invention, the lithium ions of the NCM811 and SiO-C material system has a capacity retention rate of more than 90% after 500 cycles of 1C / 1C at room temperature, and has excellent cycle performance.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a lithium ion battery electrolyte suitable for NCM811 and SiO-C material systems and a preparation method. Background technique [0002] With the rapid development of electric vehicles, the market places higher requirements on the energy density and cycle performance of lithium-ion batteries. The traditional lithium cobalt dioxide (LCO) and graphite (C) lithium-ion battery system has low energy density and high cost, which can no longer meet the market demand of electric vehicles. [0003] To increase the energy density of lithium-ion batteries, the common measure is to increase the charge cut-off voltage of the battery, but the battery is under high voltage, and the positive electrode material will have certain defects, such as structural collapse, ion mixing and metal ion dissolution; the second is to use High-energy-density ternary cathode materials are combined...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/0567H01M10/0568H01M10/0569H01M10/0525
CPCH01M10/0525H01M10/0567H01M10/0568H01M10/0569Y02E60/10
Inventor 刘远洲李宇时洪玲潘启明孙鸿飞雷树升曹珍姚琦张政
Owner SHENZHEN BAK POWER BATTERY CO LTD
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