High-energy-density lithium ion battery and preparation method thereof

Abstract

The invention relates to a high-energy-density lithium ion battery and a preparation method thereof. The high-energy-density lithium ion battery comprises a positive pole piece, a negative pole piece and a membrane, wherein an active substance on the positive pole piece is nickel cobalt lithium manganate, namely Li<1+a>Ni<x>Co<y>Mn<z>O2; an active substance on the negative pole piece is a silicon-carbon material. The preparation method of the high-energy-density lithium ion battery comprises the following steps: manufacturing the positive pole piece with the active substance, nickel cobalt lithium manganate, namely Li<1+a>Ni<x>Co<y>Mn<z>O2; manufacturing the negative pole piece with the silicon-carbon material as the active substance; coiling or laminating the positive pole piece, the negative pole piece and the celgard membrane to prepare a power battery core. The lithium ion battery provided by the invention is high in energy density, high in coulombic efficiency and high in cycling stability. The preparation method has the advantages of simple process, low cost and easiness for industrialized production.

Description

technical field [0001] The invention relates to the field of lithium ion battery materials, in particular to a high specific energy lithium ion battery and a preparation method thereof. Background technique [0002] Lithium-ion batteries have the advantages of high energy density, light weight, small size, long cycle life, no memory, and low pollution. and other equipment have a wide range of applications. At present, the specific energy density of lithium-ion batteries used in 3C electronic products is increasing day by day, especially for mobile phone batteries, the energy density has reached about 550Wh / L. In 2015, the specific energy of the new energy vehicle power battery module will reach more than 150Wh / kg. With the advancement of science and technology, people have put forward higher requirements for lithium-ion batteries (high capacity, high energy density, long cycle life, small self-discharge, no memory effect, and no pollution to the environment). [0003] In ...

AI Technical Summary

Problems solved by technology

One of the biggest problems with this type of positive electrode material is that when it is charged above 4.5V for the first time, an irreversible electrochemical reaction occurs xLi 2 MnO 3 ·(1-x)MO 2 →xMnO 2 ·(1-x)MO 2 +xLi 2 O, namely Li in the material + With Li 2 The form of O is released from the unit cell, and this part of lithium ions cannot be fully re-intercalated into the original unit cell during discharge, resulting in a large initial irreversible capacity of the material, low Coulombic efficiency, and poor cycle stability.

[0004] In order to improve the specific energy of lithium-ion batteries, anode materials with high specific capacity are developed. The theoretical specific capacity of silicon-based materials reaches 4200mAh / g. Expansion rate > 300%, leading to pulverization and shedding of materials during charging and discharging, resulting in poor battery cycle performance

[0005] The lithium-ion battery composed of the above positive and negative electrode materials consumes more active lithium for the first time, which reduces the specific energy of the battery, poor cycle performance, easy gas inflation, poor safety performance, and is difficult to be practically applied.

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