Electrolyte and lithium ion battery

A technology of electrolyte and lithium salt, applied in the field of electrolyte and lithium ion battery, can solve the problems of oxidative decomposition of electrolyte solvent, deterioration of battery cycle performance, unsatisfactory high-voltage resistance performance, etc.

Inactive Publication Date: 2018-03-16
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The prior art discloses that additives are added to the electrolyte to improve the cycle stability of high-voltage lithium-ion batteries. However, its high-voltage resistance performance is not ideal, especially at the end of battery charging, and local voltage polarization is likely to be inhomogeneous. If the overpotential is too high in the local area, the electrolyte solvent will inevitably be oxidized and decomposed, resulting in serious deterioration of the battery cycle performance

Method used

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  • Electrolyte and lithium ion battery
  • Electrolyte and lithium ion battery
  • Electrolyte and lithium ion battery

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preparation example Construction

[0034] The invention provides a preparation method of electrolyte, comprising:

[0035] Mix the solvent and lithium salt to obtain an electrolyte; the solvent is selected from one or more of fluorocarbonate solvents, sulfone solvents and nitrile solvents; the concentration of the lithium salt is 3.1-5.0mol / L .

[0036] In the present invention, the solvent and the lithium salt are mixed to obtain an electrolyte solution. The present invention does not limit the mixing method, and the mixing method well-known to those skilled in the art is sufficient.

[0037] The solvent and lithium salt have been clearly described above, and will not be repeated here.

[0038]The present invention provides a lithium ion battery, comprising the electrolyte described in the above technical solution.

[0039] In the present invention, the battery includes a positive electrode, a negative electrode, a diaphragm, and an electrolyte, and the electrolyte is the electrolyte described in the above t...

Embodiment 1

[0044] In a glove box filled with argon, weigh 15ml of fluoroethylene carbonate (FEC) and slowly add lithium salt LiPF 6 , so that the concentration of the lithium salt is 3.3mol / L, stirring until the lithium salt is completely dissolved to obtain an electrolyte.

[0045] Performance test: put 2mL of the electrolyte prepared above into a conductivity tester to measure its conductivity. The electrochemical window was measured with 3mL electrolyte. Use Li 1.16 [Mn 0.75 Ni 0.25 ] 0.84 o 2 (High-voltage positive electrode) is a button battery with positive electrode material and pure metal Li as negative electrode material. The test voltage range is 2.6-4.8V, and the charge and discharge capacity of the battery is tested at 25°C. The cycle when the capacity decays to 90% of the initial capacity The number of times is 129 times.

Embodiment 2

[0050] In a glove box filled with argon, weigh 15ml of fluoroethylene carbonate (FEC) and slowly add lithium salt LiPF 6 , so that the concentration of the lithium salt is 3.1mol / L, stirring until the lithium salt is completely dissolved to obtain an electrolyte.

[0051] Performance test: put 2mL of the electrolyte prepared above into a conductivity tester to measure its conductivity. The electrochemical window was measured with 3mL electrolyte. Use Li 1.16 [Mn 0.75 Ni 0.25 ] 0.84 o 2 (High-voltage positive electrode) is a button battery with positive electrode material and pure metal Li as negative electrode material. The test voltage range is 2.6-4.8V, and the charge and discharge capacity of the battery is tested at 25°C. The cycle when the capacity decays to 90% of the initial capacity The number of times is 108 times.

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Abstract

The invention provides an electrolyte. The electrolyte comprises a solvent and lithium salt, and the concentration of the lithium salt is 3.1-5.0 mol/L. When the high-concentration electrolyte is used, a complexation state of lithium ions and a solvent is changed from complexation of 3-4 solvent molecules by each lithium ion to complexation of 1-2 solvent molecules by one lithium ion, complexationforce of the lithium ions and the solvent molecules are strong, the energy barrier for solvent reduction is increased, and work voltage is risen. The above high-concentration electrolyte is partiallyreduced on a surface of a cathode, a layer of SEI is formed which is better than that formed through reduction of current electrolytes, so that further decomposition of the electrolyte can be inhibited, thin thickness and good toughness can be kept during a cycle process, accordingly, interface impedance and lithium ion transport number cannot be increased with increase of cycle number, and highcoulombic efficiency and specific capacity can be kept at a battery cycle late period.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to an electrolyte solution and a lithium ion battery. Background technique [0002] In recent years, due to the imminent energy crisis and energy revolution, the research on lithium-ion batteries has been further deepened, and new requirements have been put forward for the performance of lithium batteries, such as higher energy density and better safety. At present, in order to improve the energy density of lithium-ion batteries, researchers mainly develop positive and negative materials with high capacity and high working voltage. For example, there are ternary materials, lithium-rich materials and high-voltage materials for the positive electrode. Above 4.7V, while the commercial lithium-ion battery (its electrolyte is composed of organic solvent and LiPF dissolved in it) 6 composed of. Among them, organic solvents are usually binary or ternary mixed so...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/0569H01M10/0568H01M10/0525
CPCH01M10/0525H01M10/0568H01M10/0569Y02E60/10
Inventor 杨光华夏永高刘兆平
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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