Lithium ion battery system with high specific energy and ultra-low-temperature rate discharge

Abstract

The invention discloses a lithium ion battery system with high specific energy and ultra-low-temperature rate discharge. The lithium ion battery system comprises a positive electrode active material,a negative electrode active material, an electrolyte and a diaphragm; the positive electrode active material of the lithium ion battery system is a high-voltage lithium cobalt oxide material, and thecharging cut-off voltage is 4.3-4.5V; and the negative electrode active material is graphite. By selecting small-particle high-voltage lithium cobalt oxide positive electrode material, high specific energy is ensured while rate capability is improved; by adoption of soft carbon or hard carbon-coated artificial graphite, the low-temperature advantage can be played while co-embedding of an electrolyte solvent can be prevented; and a carbonic ester solvent combination capable of improving the low-temperature performance, a low-temperature synergistic additive and a high-voltage-resistant cyclingstabilizer are introduced to the electrolyte formula. The ceramic diaphragm disclosed in the invention adopts a dry method polyolefin film as the base material; and the single surface is coated with ananometer ceramic coating layer, so that the synergistic effects lies in keeping dry film high ventilation degree while improving retention rate of the electrolyte in the cycle process.

Description

technical field [0001] The invention relates to the field of lithium-ion batteries, in particular to a lithium-ion battery system with high specific energy and ultra-low temperature rate discharge. Background technique [0002] Lithium-ion batteries have the advantages of good safety performance, high cycle life, and light weight. However, due to the unsatisfactory discharge performance of conventional lithium-ion at low temperature. At low temperature, the diffusion rate of lithium ions in the electrolyte and the positive and negative electrodes drops sharply, and the viscosity of the electrolyte increases, thus causing the battery to fail to work properly. At present, in the fields of military drones, electric vehicles, and electric tools, lithium-ion batteries are more and more widely used. These fields require batteries with high specific energy and can work in harsh environments. Conventional lithium-ion batteries have gradually failed to meet the needs of the market...

AI Technical Summary

Problems solved by technology

Although the low temperature and rate performance of lithium cobalt oxide are the best among the current commercial cathode materials, the design capacity of lithium cobalt oxide is low, which affects the specific energy of the battery.

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