A coating structure suitable for high-voltage charging and discharging and its manufacturing method

Abstract

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; the surface of the positive electrode material layer is coated with a first metal oxide layer and a second metal oxide layer, and the first A metal oxide layer is coated on the surface of the positive electrode material layer, a second metal oxide layer is coated on the outer surface of the first metal oxide layer, and the weight of the first metal oxide layer accounts for the weight of the first metal oxide layer and the second metal oxide layer. 40-70% of the total weight of the second metal oxide layer. Because the structure contains active substances, the first-cycle efficiency of the material is improved; and the ceramic oxide layer on the surface can well inhibit the corrosion of HF, the dissolution of metal ions, and the extraction of active oxygen; The secondary battery is suitable for high-voltage charging and discharging (≥4.30 V), has high energy density, good cycle and safety performance, and has greatly improved high-temperature storage performance.

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 ternary lithium nickel cobalt manganese, which can effectively alleviate the dissolution of metal ions; at the same time, reduce the corrosion of active substances by HF, thereby effectively improving circulation, high temperature storage and safety. Performance, such as: the invention patent with 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 Al 2 o 3 The introduction of the material leads to a decrease in the capacity of the material, which eventually leads to a decrease in the energy density

The invention patent with the publication number CN 102244260 A also points 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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