Coating structure applicable to high-voltage charge-discharge and manufacturing method of coating structure

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a coating structure applicable to high-voltage charge-discharge and a manufacturing method of the coating structure. A first metal oxide layer and a second metal oxide layer coat the surface of a cathode material layer, the first metal oxide layer coats the surface of the cathode material layer, the second metal oxide layer coats the outer surface of the first metal oxide layer, and the weight of the first metal oxide layer occupies 40 to 70 percent of the total weight of the first metal oxide layer and the second metal oxide layer. The coating structure contains active substances, so the first charge-discharge efficiency of a material is improved; by a surface ceramic oxide layer, corrosion of hydrogen fluoride (HF), release of metal ions and extraction of active oxygen are well inhibited; and a lithium ion secondary battery with the structure is applicable to charge-discharge at high voltage of more than 4.30 V, high in energy density, high in cycle performance and high in safety performance, and high-temperature storage performance is greatly improved.

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to a coating structure suitable for high-voltage charging and discharging and a manufacturing method thereof. Background technique [0002] The ternary lithium-nickel-cobalt-manganese (NCM) material has attracted extensive attention from researchers because of its high capacity (up to 250 mAh / g, 91% of the theoretical capacity), good safety, and low price. However, due to the existence of high-valent nickel during the charge and discharge process, the surface structure of the ternary lithium nickel cobalt manganese material is unstable, and it is easily corroded by HF in the electrolyte during the high voltage charge and discharge process, which makes the capacity decay faster, limiting for its use at high voltages. At present, the main method to solve these problems is to coat the surface of ternary lithium nickel cobalt manganese, which can effectively alleviate the...

AI Technical Summary

Problems solved by technology

However, due to the existence of high-valent nickel during the charge and discharge process, the surface structure of the ternary lithium nickel cobalt manganese material is unstable, and it is easily corroded by HF in the electrolyte during the high voltage charge and discharge process, which makes the capacity decay faster, limiting for its use at high voltage

At present, the main method to solve these problems is to coat the surface of the ternary lithium nickel cobalt manganese. The coating can effectively alleviate the dissolution of metal ions; at the same time, it can reduce the corrosion of active substances by HF, thereby effectively improving circulation, high temperature storage and safety. Performance, such as: the invention patent with the publication number CN 102364723 A uses aluminum coating to coat the ternary lithium nickel cobalt manganese to improve its cycle performance, however, the inactive material Al2O3 leads to a decrease in material capacity, which eventually leads to a decrease in energy density

The invention patent with the publication number CN 102244260 A also pointed out that a layer of composite oxides of Al and Sn or Al and Co is coated on the surface of the ternary lithium nickel cobalt manganese, due to the introduction of active materials (Co and Sn), the maximum suppression However, this kind of coating has an obvious defect, Co is exposed on the surface and is easy to dissolve, resulting in a decrease in cycle performance; at the same time, in the entire coating process, water is used as a solvent, resulting in ternary lithium nickel The surface of cobalt manganese deteriorates, which further deteriorates the cycle performance

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