Lithium ion battery

Abstract

The invention provides a lithium ion battery. The lithium ion battery comprises a positive plate which comprises a positive diaphragm; a negative plate which comprises a negative diaphragm; and an electrolyte including an organic solvent and an additive. The double-sided coating weight of the positive diaphragm is 28-56mg / cm <2>, and the compaction density is not less than 3.5 g / cm <3>; the double-sided coating weight of the negative electrode diaphragm is 14-28mg / cm <2>, and the compaction density is not less than 1.4 g / cm <3>; the organic solvent comprises linear carboxylic ester with a structure as shown in a formula I; in the formula I, R1 and R2 are independently selected from alkyl with 2-4 carbon atoms respectively; the mass fraction of the linear carboxylic ester with the structureas shown in the formula I in the organic solvent is 5-60%; the additive is prepared from 1, 3-propane sultone and fluoroethylene carbonate; the mass fraction of the 1, 3-propane sultone in the electrolyte is 0.1%-5%; the mass fraction of the fluoroethylene carbonate in the electrolyte is 0.1%-7%. The lithium ion battery provided by the invention has high energy density, high initial coulombic efficiency, excellent rapid charging performance and low-temperature charging performance at the same time.

Description

[0001] This application is a divisional application of the original invention patent application (the application date is October 16, 2015, the application number is 201510673313.8, and the invention name is "lithium-ion battery"). technical field [0002] The invention relates to the technical field of batteries, in particular to a lithium ion battery. Background technique [0003] Lithium-ion batteries have unique advantages such as high energy density, high working voltage, low self-discharge rate, long cycle life, and no pollution. They have been widely used as power sources in mobile electronic products such as mobile phones and notebook computers. However, with the expansion of market demand for electronic products and the development of network technology, users put forward higher requirements for lithium-ion batteries. High energy density and excellent fast charging performance directly affect the user experience. [0004] At present, there are several ways to increa...

AI Technical Summary

Problems solved by technology

A small amount of FEC can significantly improve the normal temperature cycle performance of lithium-ion batteries, but a high content of FEC has two disadvantages: First, when the positive and negative are extremely high coating weight and high compaction density, this thicker interface film will It will lead to serious lithium precipitation in the battery; second, high-content FEC will decompose a large amount of HF, especially at high temperature, the gas production is very significant, affecting battery storage and high-temperature cycle performance (reaction formula Ⅰ)

[0007] 1,3-propane sultone (PS) can also be used as an additive to the electrolyte to participate in the electrochemical process of the battery. The disadvantage of PS is its reduction potential (0.7V VS Li / Li + ) is closer to the reduction potential of cyclic carbonates (0.5V VS Li / Li + )(K.Xu,Chemical Reviews 2014), so it is not suitable to be used alone as an anode film-forming additive

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