Lithium nickel cobalt manganese aluminate positive electrode material with shell-core-shell structure and preparation method of lithium nickel cobalt manganese aluminate positive electrode material

Abstract

The invention discloses a lithium nickel cobalt manganese aluminate positive electrode material with a shell-core-shell structure and a preparation method of the lithium nickel cobalt manganese aluminate positive electrode material. The preparation method comprises the steps of taking Co-based MOF (zif-67) as a crystal nucleus for nickel, cobalt, manganese and aluminum coprecipitation reaction, generating a high-nickel quaternary component precursor with a core-shell structure, evenly mixing the precursor, lithium salt and an additive according to a certain proportion, calcining in an oxygen atmosphere furnace, and obtaining a primary sintered matrix; crushing, washing, filter-pressing and dehydrating the primary sintered matrix to obtain a filter cake containing certain moisture, uniformly mixing the filter cake and a coating material, drying at a low temperature, and carrying out secondary sintering in an oxygen atmosphere furnace to obtain the high-nickel quaternary component positive electrode material with a 'shell-core-shell' sandwich hollow structure. The positive electrode material not only has relatively high initial discharge specific capacity, relatively low internal resistance and relatively good rate capability, but also has good cycling stability and safety performance.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a nickel-cobalt-manganese-aluminate positive electrode material with a core-shell structure and a preparation method thereof. Background technique [0002] As an energy-saving and environmentally friendly energy source, lithium-ion batteries have the characteristics of high energy density, long cycle life, and good safety. They have become the main choice for mobile electronic devices and new energy vehicles. With the increasing demand of consumers and the continuous change of lithium-ion battery technology, lithium-ion batteries are currently developing in the direction of higher specific energy, higher power, longer life and higher safety performance. [0003] Cathode materials are one of the key factors determining the performance of lithium-ion batteries. Among them, nickel-cobalt lithium manganese oxide and nickel-cobalt lithium aluminate ternary cathode materi...

AI Technical Summary

Problems solved by technology

However, the problem with secondary particles with a hollow structure is that when the secondary particles are to be coated when making positive electrode materials, the coating layer only exists on the surface of the secondary particles, and it is difficult to enter the interior of the secondary particles, forming a uniform particle in the hollow area. Cladding, even wet cladding faces this problem

The particle cracks formed by the secondary particles of the hollow structure during the long cycle provide a channel for the electrolyte to infiltrate into the hollow area inside the particle (the secondary particles have particle cracks in the first week of the cycle), although the hollow structure The apparent lithium ion diffusion coefficient of the secondary particles increases, the first coulombic efficiency increases, and the rate performance improves, but the direct contact between the inner layer particles without a uniform coating layer and the electrolyte leads to the preferential deterioration of the inner layer structure, thereby rapidly fading the capacity. reduced cycle life

At the same time, the hollow structure does not improve the thermal stability and safety performance of high-nickel ternary secondary granular cathode materials.

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