Method for improving electrochemical performance of high nickel ternary cathode material through silicon dioxide/sodium collaborative modification

Abstract

The invention discloses a method for improving electrochemical performance of a high nickel ternary cathode material through silicon dioxide/sodium collaborative modification. The method comprises thesteps of (1) respectively dissolving nickel, cobalt and manganese sources and urea in distilled water, transferring the solutions to a reactor after sufficient dissolution, then placing the reactor in an oven for reaction to obtain milky yellow powder of a high nickel ternary precursor; (2) sufficiently grinding the precursor, a lithium source and a sodium source to obtain a mixture, carrying outtwo-stage high temperature sintering on the mixture in an oxygen atmosphere in a tubular furnace, and cooling to the room temperature along with the furnace temperature to obtain Li<0.9>Na<0.1>Ni<0.8>Co<0.1>Mn<0.1>O2; and (3) mixing ethyl orthosilicate and water, then adding the mixture to Li<0.9>Na<0.1>Ni<0.8>Co<0.1>Mn<0.1>O2, stirring, drying, adding a small amount of absolute ethyl alcohol, grinding and then preserving the temperature for a period of time in a Muffle furnace to obtain an SiO2/ Li<0.9>Na<0.1>Ni<0.8>Co<0.1>Mn<0.1>O2 composite material. The method has the advantages of simpleprocess and low cost and prepares the silicon dioxide coated SiO2/ Li<0.9>Na<0.1>Ni<0.8>Co<0.1>Mn<0.1>O2 composite material with good electrochemical performance such as high rate performance and cycle performance.

Description

technical field [0001] The invention relates to the field of lithium-ion batteries, in particular to a method for improving the electrochemical performance of high-nickel ternary positive electrode materials through silicon dioxide / sodium synergistic modification. Background technique [0002] In recent years, due to the advantages of high specific energy, long cycle life, good safety, green and pollution-free, lithium-ion secondary batteries have been widely used in various portable electronic products, automobile industry and military industry. Cathode materials are an important part of lithium-ion batteries, and the performance of cathode materials is directly related to the performance of lithium-ion batteries. Nickel-cobalt-manganese ternary material is a cathode material with a layered structure, which has the characteristics of high specific capacity, good cycle performance, good safety, low cost, and easy synthesis. The high capacity and high safety of this material...

AI Technical Summary

Problems solved by technology

[0003] (1) Because the radii of Ni ions and Li ions are similar, it is easy to cause mixed cations

The cation mixing effect will cause the first charge and discharge efficiency of the ternary material to be low during the charge and discharge process.

[0004] (2) The thermodynamic stability of layered materials under heating conditions is still unclear, and high-capacity Li-ion batteries are very dangerous during charging if an exothermic reaction occurs between the active material and the electrolyte

[0005] (3) The lithium ion diffusion coefficient and electronic conductivity are low, which makes the rate performance of the material not very ideal

[0006] (4) The ternary material is a secondary spherical particle formed by the agglomeration of the primary particles. Since the secondary particles will be broken at a higher compaction density, the compaction of the ternary material electrode is limited, which also limits the capacity of the battery cell. Further increase in energy density

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