Lithium ion battery

Abstract

The present invention provides a lithium ion battery, which comprises: a positive electrode sheet, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode membrane sheet arranged on the positive electrode current collector; a negative electrode sheet, wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode membrane sheet arranged on the negative electrode current collector; a separation membrane arranged between the positive electrode sheet and the negative electrode sheet in a spacer manner; and a non-aqueous electrolyte, wherein the non-aqueous electrolyte comprises a lithium salt, a non-aqueous organic solvent and an additive, both surface coating weights of the positive electrode membrane sheet are not less than 28 mg / cm<2> and the compaction density is not less than 3.5 g / cm<3>, both surface coating weights of the negative electrode membrane sheet is not less than 14 mg / cm<2> and the compaction density is not less than 1.4 g / cm<3>, the non-aqueous organic solvent comprises a linear carboxylic acid ester having a structure represented by a formula I, R1 and R2 in the formula I are respectively and independently selected from C2-C4 alkyl, and the additive comprises 1,3-propanesultone and fluoroethylene carbonate. The lithium ion battery of the present invention has advantages of high energy density, high first Kurun efficiency, excellent fast charging performance, and excellent low-temperature charging performance. The formula I is defined in the specification.

Description

technical field [0001] The invention relates to the technical field of batteries, in particular to a lithium ion battery. Background technique [0002] 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. [0003] At present, there are several ways to increase the energy density of lithium-ion batteries. (1) Develop positive electrode active materials for high-voltage systems. However, the current positive electrode active materials for applications above 4.4V are not perfect, and some ...

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)

[0006] 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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