Modification method of ternary cathode material

Abstract

The invention provides a modification method of a ternary positive electrode material. The modification method comprises the following steps of 1) dispersing a nickel salt, a cobalt salt and a manganese salt in a dispersion solvent according to a certain proportion, adding a lithium salt solution and a modifying agent solution to form a mixed solution at a certain dropping speed after uniform stirring, and controlling pH of the mixed solution during the dropping process; 2) performing spray drying to obtain first powder after the mixed solution is stirred for a certain time, performing roasting for 5-8 hours under a temperature of 400-600 DEG C, performing grinding after cooling to a room temperature, performing roasting for 10 hours under a temperature of 900 DEG C, and performing grinding again to form second powder after cooling to the room temperature; 3) mixing and ball-milling the second powder, a certain amount of modifying agent and alcohol, performing baking for 10-20 hours to form third powder under a temperature of 60-80 DEG C; and 4) placing the third powder in a tubular furnace to which ammonia gas is continuously introduced, performing nitridation for 0.5 hour under a temperature of 500 DEG C, and obtaining the composite modified ternary positive electrode material after cooling to the room temperature.

Description

【Technical field】 [0001] The invention belongs to the technical field of batteries, in particular to a method for modifying a ternary cathode material. 【Background technique】 [0002] At present, battery technology is still the main technical bottleneck restricting the development of electric vehicles. The ternary cathode material has attracted extensive research due to its advantages such as ultra-high specific capacity, high working voltage platform and high thermal stability. Due to the high charge cut-off voltage of this material , The charging and discharging process will cause structural collapse, oxygen evolution will cause safety hazards, and there are also defects such as high initial irreversible capacity and poor rate performance that hinder its commercialization process. [0003] For the above-mentioned defects in ternary cathode materials, the general modification methods are mainly element doping and surface coating. Element doping is mainly metal cation and f...

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Problems solved by technology

Element doping is mainly metal cation and fluorine anion doping, which can enhance the structural stability of the material to a certain extent, but there is uneven doping, and the doping elements are distributed on the surface and bulk phase of the material particles, which is easy to form impurity phases. Doping cannot solve the oxygen evolution problem of the material under high voltage; the surface coating technology is to coat a protective layer on the surface of the lithium-rich ternary positive electrode material. The protective layer is electrochemically inert and can suppress the high voltage of the material to a certain extent. The structural collapse caused by charging and discharging can alleviate the corrosion of the electrode material by the electrolyte, and at the same time improve the conductivity of the material, but there is uneven coating, the process is complicated, and a large amount of toxic industrial wastewater is formed at the same time, and coating is the same as doping. Can not solve the oxygen evolution problem of materials under high voltage charge and discharge

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