Lithium ion battery and preparation method thereof

Abstract

The invention relates to a lithium ion battery comprising a shell, an electric core arranged inside the shell and electrolyte, wherein the electric core comprises a positive electrode, a negative electrode, and a membrane for separating the positive electrode from the positive electrode; the positive electrode comprises a positive electrode piece and a positive electrode material layer coated on the surface of the positive electrode piece; the negative electrode comprises a negative electrode piece and a negative electrode material layer coated on the surface of the negative electrode piece; the density of the coating face of the positive electrode material layer is 25-36mg / cm<2>; the density of the coating face of the negative electrode material layer is less than or equal to 36mg / cm<2>; and a ratio of the reversible capacity of the positive electrode to the reversible capacity of the negative electrode is (1.2:1)-(1.5:1). The negative electrode comprises the negative electrode piece, a negative electrode inner coating coated on the surface of the negative electrode piece, and a negative electrode outer coating coated on the surface of the negative electrode inner coating. The lithium ion battery has high multiplying power, high working voltage, high energy density, and low self discharge rate. The invention simultaneously provides a preparation method of the lithium ion battery.

Description

technical field [0001] The invention belongs to the technical field of lithium batteries, and in particular relates to a lithium ion battery and a preparation method thereof. Background technique [0002] In the 1980s, American scholar J.B.Goodenough and others first discovered lithium cobalt oxide (LiCoO 2 ), lithium nickelate (LiNiO 2 ) and lithium manganate (LiMn 2 o 4 ) can be used as a material for deintercalating lithium ions. In the 1990s, Sony successfully applied lithium cobalt oxide to commercial small electronic products for the first time. Since then, lithium-ion batteries have been widely used in various electronic devices due to their high cycle performance, high reliability and low pollution. In recent years, with the continuous development of science and technology, the functions of electronic equipment have been continuously upgraded, so higher requirements have been put forward for the energy and rate performance of lithium batteries. High-energy and hi...

AI Technical Summary

Problems solved by technology

However, in order to improve the safety of lithium-ion batteries, manufacturers usually design the ratio of the reversible capacity of the positive electrode to the reversible capacity of the negative electrode to be less than 1, which makes the energy density of lithium-ion batteries low, and its capacity is difficult to meet the needs of electronic devices with continuously upgraded functions. Large rate discharge, high voltage and high energy requirements

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