Anode material of lithium ion cell and preparation method

Abstract

The anode material is prepared from oxidation material layer of covering surface of at least one anode active material among LiCoO2, LiNi1-xCOxO2, LiNi1 / 3Mn1 / 3O2 and LiMn2O4. Weight of non-oxygen element in oxidation material layer can be 0.01-10 weight% of anode active material. Advantages of the anode material are: good cycle performance, favorable high temp property and high power discharge property, and anti over change property as well as simple technique and easy of production.

Description

【Technical field】 [0001] The invention relates to a lithium ion battery cathode material and a preparation method thereof, in particular to a lithium ion battery cathode material with good cycle performance and good high temperature performance and a preparation method thereof. 【Background technique】 [0002] As the functions of electrical products, especially portable electrical products, are becoming more and more complex, and the volume is becoming smaller and smaller, the requirements for the power supply are also increasing, which is reflected in: higher capacity, suitable cycle life, good high temperature performance, good high rate Discharge performance and anti-overcharge performance, etc. Lithium-ion batteries have developed rapidly and are widely used in the past ten years due to their superior comprehensive performance. [0003] In lithium-ion batteries, the performance of the cathode material has a direct impact on the performance of the lithium-ion battery. At ...

AI Technical Summary

Problems solved by technology

When the lithium-ion battery is repeatedly charged and discharged, especially when it is charged to a high voltage above 4.2V, the above-mentioned positive electrode active material is prone to lattice deformation and decomposition, and oxygen is generated. Oxidative decomposition of liquid, battery thermal stability and safety decrease

[0004] Trace amounts of water in the non-aqueous electrolyte used in lithium-ion batteries will also react with lithium salts such as LiPF6 in the electrolyte to produce HF acid, which will react with the positive active material in the battery, resulting in The crystal structure of the material is destroyed, thus reducing the cycle performance of the cathode material, especially at high temperatures

[0005] In addition, during the charging and discharging process of lithium-ion batteries, since the diffusion rate of lithium ions in the unit cell of the positive electrode material is significantly lower than that in the electrolyte, the concentration of lithium ions on the surface of the positive electrode material in contact with the electrolyte is different. Very large, and the ionic conductivity is also low, so it is easy to make the battery capacity drop during the battery cycle

[0006] In order to improve the above performance, Japanese Patent Laid-Open No. 2001-143703 adopts adding a kind of ultrafine alumina powder to lithium cobaltate, and then heat treatment makes the contact between alumina and lithium cobaltate particles close, but this solid substance is mutually The method of mixing is easy to make the material mixed unevenly, resulting in uneven material

In the Samsung patent CN1274956A, materials such as Si, B, Ti, Ga, Ge, Al or their oxides are added to positive electrode active materials such as lithium manganate and lithium nickelate, but this method of mixing solid powders is easy to make the material The mixing is not uniform, and there is no heat treatment after mixing, the additives and active substances must not be combined very tightly, so the effect may not be good

Li a Ni 1-x-y co x m y o 2 The surface of the surface is treated with a metal alkoxide solution such as aluminum isopropoxide and then heat-treated to obtain a layer of metal oxide coating, but in this method, the metal alkoxide as an additive is not safe, and it is easy to cause safety accidents

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