Low-temperature type lithium ion battery with high voltage and high volume energy density

Abstract

The invention provides a low-temperature type lithium ion battery with high voltage and high volume energy density. The low-temperature type lithium ion battery comprises a cathode, an anode, an isolating membrane and an electrolyte solution, wherein the isolating membrane is formed by coating polyvinylidene fluoride-hexafluoropropylene copolymer coatings on both sides of a polyolefin isolating membrane substrate. According to the low-temperature type lithium ion battery with high voltage and high volume energy density provided by the invention, the polyvinylidene fluoride-hexafluoropropylene copolymer coated on the surfaces of the isolating membrane can polymerize with polyvinylidene fluoride in positive and negative pole pieces, so that the cathode and the anode are tightly attached with the isolating membrane together, the expansion of the cathode and the anode is reduced, the inner volume of the battery is further reduced, and the energy density is improved; moreover, the polyvinylidene fluoride on the surfaces of the isolating membrane has good electrolyte retention, and is matched with the low-temperature type lithium ion electrolyte solution and good cathode and anode space conducting network, so that lithium ions can be relatively high in diffusion and disembedding speed between the electrolyte solution and the cathode and the anode under low temperature, and the discharging capacity of greater than or equal to 90% at -20 DEG C can be realized.

Description

technical field [0001] The invention relates to the field of lithium-ion batteries, in particular to a high-voltage, high-volume, energy-density, low-temperature lithium-ion battery. Background technique [0002] Lithium-ion batteries are widely used in people's daily life. With the development of wearable devices and portable electronic devices in the direction of thinner and more The standby time in winter or low temperature environment has higher and higher requirements for lithium-ion batteries. [0003] There are many ways to increase the energy density of batteries, such as selecting high-capacity positive and negative electrode materials, selecting thinner auxiliary materials, and increasing the charging voltage. Among them, increasing the charging voltage is one of the effective ways to increase the volumetric energy density of lithium-ion batteries. However, as the charging voltage increases, the safety performance and cycle performance of lithium-ion batteries dec...

AI Technical Summary

Problems solved by technology

However, as the charging voltage increases, the safety performance and cycle performance of lithium-ion batteries decline. At the same time, the increase in volumetric energy density is often accompanied by the increase in the coating surface density and compaction density of the positive and negative electrodes, resulting in lithium-ion battery life at low temperature. The diffusion resistance under the environment becomes larger, so the low-temperature performance of high-energy-density lithium-ion batteries is poor, which cannot meet people's needs in winter or low-temperature environments

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