High-temperature stable nickel cobalt lithium manganate composite electrode, and preparation method and application thereof

Abstract

The invention provides a high-temperature stable nickel cobalt lithium manganate composite electrode, and a preparation method and application thereof. The high-temperature stable nickel cobalt lithium manganate composite electrode is of a core shell structure; nickel cobalt lithium manganate is an original core; two-dimensional nanometer materials coat the surface of the nickel cobalt lithium manganate; lithium iron phosphate coats the outer surfaces of the two-dimensional nanometer materials, wherein the two-dimensional nanometer materials comprise one material or combination of several materials from VOPO4.2H2O, vanadium disulfide, tungsten disulfide and germylene. The high-temperature stable nickel cobalt lithium manganate composite electrode provided by the invention has the advantages that the corrosion of electrolyte on the nickel cobalt lithium manganate is prevented; the high-temperature stability and the circulation stability of the nickel cobalt lithium manganate are improved; the two-dimensional nanometer materials are used as a middle layer, so that a nickel cobalt lithium manganate voltage platform can be balanced; the electric conductibility and the rate capability of the whole composite material are improved; the sharp decay of the electric conductibility of the nickel cobalt lithium manganate caused by a lithium manganese phosphate layer is prevented.

Description

technical field [0001] The invention belongs to the technical field of positive electrode materials for lithium ion batteries, and relates to a high-temperature stable nickel-cobalt-lithium manganese oxide composite electrode and a preparation method and application thereof. Background technique [0002] At present, there are three main material systems in the automotive power lithium battery market: lithium manganese oxide battery, lithium iron phosphate battery, and nickel-cobalt-manganese ternary material lithium battery. Relatively speaking, the ternary lithium-ion power battery was the first to be used, and has the advantages of the highest energy density, mature technology, high platform voltage, and mature raw material supply. It is also the most widely used in electric bicycles and motorcycles. Due to its safety and service life, the high-capacity and high-voltage ternary lithium power battery pack is very dangerous, which restricts its application in pure electric ...

AI Technical Summary

Problems solved by technology

Although the invention improves the cycle performance and overcharge and overdischarge problems of nickel-cobalt lithium manganese oxide lithium-ion batteries, the invention uses the formed lithium iron phosphate material to modify the surface of nickel manganese oxide lithium material. It only stays on the surface of large particles, does not separate the lithium nickel manganese oxide in the inner layer from the electrolyte, and has a limited inhibitory effect on the reaction between the electrode and the electrolyte, making the cycle stability of the material poor. The advantages of lithium iron phosphate and lithium nickel manganese oxide are completely complementary

CN104733708A discloses a method for growing lithium iron phosphate on the surface of nickel-cobalt lithium manganese oxide particles by using a hydrothermal method, coating and modifying the surface of nickel-cobalt lithium manganese oxide so that the inner layer of lithium nickel manganese oxide material is separated from the electrolyte, effectively inhibiting the The reaction between the electrode material and the electrolyte is improved, the structural stability of the material is improved, and the prepared composite material has good cycle performance and safety performance. The lithium iron phosphate directly prepared by the hydrothermal method in this invention is not coated with carbon. The lithium iron phosphate material on the surface itself has a low discharge specific capacity and poor ion and electronic conductivity, thus reducing the discharge capacity of the composite material.

[0005] It can be seen that the mixed use of lithium iron phosphate and nickel-cobalt lithium manganate materials with different structures does have a certain impact on the improvement of the electrochemical performance of the material, but how to make the lithium iron phosphate and nickel-cobalt lithium manganate Composite materials give full play to their respective advantages at the same time. While improving the safety of nickel-cobalt-lithium manganese oxide, they can also maintain its high specific capacity. This problem has not yet been resolved.