High-voltage ternary positive electrode material with core-shell structure and preparation method of high-voltage ternary positive electrode material

Abstract

The invention provides a high-voltage ternary positive electrode material with a core-shell structure and a preparation method thereof, the chemical formula of the high-voltage ternary positive electrode material is LixNiaMnbCocMdO2, 1.03 < x < = 1.3, 0.50 < = a < = 0.65, 0.30 < = b < = 0.45, 0 < c < = 0.10, a + b + c = 1, and 0 < = d < = 0.025, the high-voltage ternary positive electrode material comprises an inner core and a shell layer; the inner core comprises a nickel manganese lithium cobalt oxide ternary material, and the molar ratio of nickel to manganese to cobalt is (0.65 to 0.80) to (0.05 to 0.60) to (0.02 to 0.15); the shell layer comprises a lithium nickel manganese oxide binary material, and the molar ratio of nickel to manganese is (0.10-0.60): (0.60-0.90); wherein M is a doping element from an inner core and/or a shell layer. The high-voltage ternary positive electrode material disclosed by the invention can stably work under the ultrahigh voltage of 4.7 V, and has ultrahigh specific discharge capacity and excellent rate capability.

Description

technical field [0001] The invention belongs to the technical field of cathode materials for lithium ion batteries, and in particular relates to a high-voltage ternary cathode material with a core-shell structure and a preparation method thereof. Background technique [0002] The development of high-nickel layered and medium-low-nickel high-voltage layered oxides is currently two technical routes to achieve high energy density of lithium-ion battery cathode materials. However, with the increase of Ni content, the cycle performance and thermal stability of high-nickel secondary ball particles are significantly reduced. Due to the increase in the degree of lithium-nickel mixing, the stability of the material surface is deteriorated. H2→H3 phase transition occurs in the medium and accompanied by oxygen release, resulting in repeated contraction and expansion of the lattice constant and unit cell volume, resulting in stress that causes the particles to break, and the electrolyte...

AI Technical Summary

Problems solved by technology

[0004] Although the above-mentioned technical scheme has targetedly improved the structure and / or surface stability of the material, and improved the electrochemical performance of a certain aspect of the material, in essence, it cannot make the positive electrode material more stable from the structure of the material itself. Performance is optimized, often with trade-offs in terms of different electrochemical performance metrics or cost

Al(PO) mentioned in CN202110525350.X patent 3 ) 3 Coating the NCM811 positive electrode material improves the surface stability of the material, but there are problems such as uneven coating when the coating amount is too small, and the capacity of the material is seriously affected when the coating amount is too large, and it has no effect on improving the working voltage of the positive electrode material. Beneficial effect

CN201810954002.2 patent proposes a high-nickel ternary cathode material modified by doping with alkali metal elements or non-metal elements. Although the structural stability of the material is improved, the improvement of material performance by this method cannot meet the current market demand , and the material obtained by this method cannot further increase the energy density of the material by increasing the working voltage

CN202110416541.2 patent achieved the first charge-discharge specific capacity of 184mAh / g under the 4.6V high-voltage test system through single crystallization, but the technologies and methods involved in this method cannot avoid problems such as poor rate and cycle performance of single crystal materials

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