Cobalt-free high-nickel ternary gradient lithium ion battery positive electrode material and preparation method thereof

Abstract

The invention belongs to the technical field of lithium ion battery positive electrode materials, and discloses a cobalt-free high-nickel ternary gradient lithium ion battery positive electrode material and a preparation method thereof. The positive electrode material comprises a body material and a coating material, the chemical formula of the body material is LiNixMyMnzO2, x is more than or equal to 0.7 and less than or equal to 0.9, z is more than or equal to 0.05 and less than or equal to 0.2, and x + y + z = 1; m is one of Zr, V, Mg, Al, Sr, La, Ce, W, Ti or Zn, and the coating material is Li2TiO3 and Li2ZrO3. According to the gradient design, the nickel content is gradually reduced from the material core body to the outer shell layer, the high-nickel core body provides relatively high capacity, along with the reduction of nickel, the side reaction caused by contact between the high-nickel material and electrolyte is reduced, and the cycling stability of the positive electrode material is improved; and the coating layer forms a protective layer, so that the problem of side reaction on the surface of the positive electrode material is solved, and meanwhile, the conductivity is also enhanced.

Description

technical field [0001] The invention relates to the technical field of lithium ion battery cathode materials, in particular to a cobalt-free and high nickel ternary gradient lithium ion battery cathode material and a preparation method thereof. Background technique [0002] With the increasing energy crisis, it is imminent to find a new type of green energy that can replace traditional petroleum energy. Lithium-ion batteries have attracted extensive attention of researchers due to their high reversible capacity, long cycle life, environmental friendliness, and wide application range. [0003] Among the cathode materials for lithium-ion batteries, nickel-cobalt-manganese (NCM) ternary materials combine the properties of lithium nickelate, lithium cobaltate, and lithium manganate materials, and have the advantages of high specific capacity, long cycle life, and high stability. Widely used in lithium-ion battery cathode materials. Cobalt plays a vital role in traditional NCM t...

AI Technical Summary

Problems solved by technology

Cobalt plays a vital role in traditional NCM ternary materials. However, in recent years, the price of cobalt has gradually increased, resulting in a soaring price of traditional cathode materials, which seriously limits the wide application of lithium-ion batteries. Therefore, high nickel or Cobalt-free and high-nickel cathode materials have been developed

In practical applications, the removal of cobalt can significantly reduce the cost, but the nickel-manganese (NM) cathode material shows poor cycle stability

[0004] On this basis, researchers have improved the specific capacity and stability of cobalt-free high-nickel cathode materials by replacing cobalt elements and element doping, but the electrochemical performance of the obtained materials cannot meet expectations.

For example, the patent CN113889615A uses tungsten instead of cobalt to provide a cobalt-free high-nickel ternary concentration gradient core-shell structure lithium-ion battery positive electrode material, but the electrochemical performance of this material is poor, and the discharge specific capacity is the highest at 1C rate. It is 188.6mAh / g, which cannot meet the current requirements for higher specific capacity performance

As another example, the patent CN110970601A discloses a double-gradient coated high-nickel ternary positive electrode material. Although the material is a high-nickel material, there is still a certain amount of cobalt, which cannot fundamentally solve the problem of the cobalt-free system.

As another example, patents CN106910874A, CN111628149A, etc. all disclose gradient high-nickel ternary positive electrode materials, the first discharge capacity can reach 200mAh / g, and have excellent electrochemical performance, but they are all NCM systems, and the use of cobalt cannot be completely avoided

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