A lithium-ion battery with improved low-temperature charge-discharge performance

Abstract

The invention discloses a lithium ion battery with improved low temperature charge and discharge performances. A positive material of the lithium ion battery comprises, by mass, 45-47% of a nickel-cobalt-manganese ternary material, 45-47% of lithium manganate, 3-5% of polyvinylidene fluoride, 0.5-1% of conductive carbon black, 1-3% of vapor grown carbon fibers, and 0.5-1.5% of carbon nanotubes. A negative material of the lithium ion battery comprises, by mass, 63-66% of artificial modified graphite, 28-30% of soft carbon, 0.5-1% of conductive carbon black, 0.5-1% of vapor grown carbon fibers, 0.5-1% of carbon nanotubes, 1-2% of carboxymethylcellulose and 2-3% of styrene-butadiene rubber. A diaphragm of the lithium ion battery is a ceramic diaphragm. An electrolyte of the lithium ion battery comprises an electrolyte and a solvent. The electrolyte is lithium hexafluorophosphate. The electrolyte has a lithium hexafluorophosphate concentration of 1-1.2mol / L. The solvent is prepared from ethylene carbonate, dimethyl carbonate, gamma-butyrolactone, methyl acetate and propylene carbonate according to a mass-to-volume ratio of (1-2): (1-2): (0.1-0.3): (0.3-0.5): (0.1-0.3). The lithium ion battery has low internal resistance and good charging and discharging capability in a low temperature state.

Description

technical field [0001] The invention relates to a lithium ion battery, in particular to a lithium ion battery with improved low-temperature charging and discharging performance. Background technique [0002] At present, lithium-ion batteries have been widely used due to their advantages of light weight, high energy density, small self-discharge, long life, high discharge power and environmental protection. Lithium-ion batteries include four major material parts: positive electrode, negative electrode, diaphragm and electrolyte. These four major material parts directly affect the performance of lithium-ion batteries. The low temperature cycle performance is slightly insufficient. At low temperature, especially at -20°C~-30°C, the internal resistance of the battery increases significantly, and the power supply voltage may not be able to discharge the power directly or the discharge power may be greatly attenuated, even at It cannot be charged at low temperature. Therefore, i...

AI Technical Summary

Problems solved by technology

Its disadvantage is that when the battery is in a low temperature state, it is necessary to sacrifice part of the power of the lithium-ion battery to make the heating component run for heat supply, which will greatly reduce the capacity of the battery. The battery will be depleted quickly