Gradient-doped high-nickel ternary positive electrode material and preparation method thereof

Abstract

A physical structure of a gradient-doped high-nickel ternary positive electrode material comprises an inner core and a shell coating the outer surface of the inner core. A preparation method of the gradient-doped high-nickel ternary positive electrode material comprises the following steps: preparing a salt solution of nickel, cobalt and manganese, the salt solution being one of a sulfate solution, a nitrate solution and a chloride solution; adding the salt solution and a sodium hydroxide solution into a reaction kettle, pumping an ammonia water solution into the reaction kettle, and after theobtained particles of which the inner cores are the nickel-cobalt-manganese ternary precursors grow to 85%-95% of the target particle size, adding a doping solution into the reaction kettle in a gradient manner; sequentially carrying out centrifugal washing, drying, screening and iron removal on the obtained ternary precursor particles with the target particle size to obtain a ternary precursor;and mixing the ternary precursor with lithium hydroxide monohydrate, and carrying out sintering, dissociating and screening to obtain the nickel-cobalt-manganese ternary positive electrode material doped with the concentration gradient. The purpose of gradient doping is achieved in a doping element gradient feeding mode, and the cycle performance of the material is optimized under the condition that the doping amount is as small as possible.

Description

technical field [0001] The invention belongs to the technical field of compound preparation methods, and in particular relates to a gradient-doped high-nickel ternary positive electrode material and a preparation method thereof. Background technique [0002] With the increasing demand for lithium-ion batteries for electric vehicles and energy storage grids, high-nickel layered oxides, LiNi x co y mn z o 2 (x+y+z=1, x≥0.7), is considered to be one of the most promising cathode materials due to its advantages of high capacity and low cost. However, its poor stability restricts its commercial use, and a large number of studies have been devoted to revealing the reasons for its poor stability and improving its stability. A large number of studies have proved that under the premise of not excessively reducing the electrochemical performance of the material, element doping on the surface of the ternary cathode material can effectively isolate the electrolyte from the active ma...

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Problems solved by technology

In the process of preparing lithium salt, element doping is carried out by means of solid-phase doping elements, which will cause local enrichment of doping elements, interfere with the uniformity of product particles, reduce product stability, and affect the electrical properties of materials to a certain extent. Capacity; while the coprecipitation method generally uses full-concentration doping, less doping can not effectively improve the cycle performance, and too much doping will cause a decrease in capacity, so the choice of doping amount seriously affects its material properties

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