Preparation method of silicon-based composite modified lithium iron phosphate positive electrode material, positive electrode and battery

Abstract

This invention relates to the field of cathode material technology, specifically to a method for preparing silicon-based composite modified lithium iron phosphate cathode materials, a cathode, and a battery; it addresses the problems of low electrochemical performance, energy density, and conductivity of existing lithium iron phosphate cathodes; and it achieves this by synergistically doping lithium iron phosphate with Mn-Na and Mn... 2+ Partially replaces Fe 2+ The position of Na increases the average operating voltage of the material, thereby improving the energy density. + The ionic radius is greater than that of Li + The ionic radius is increased, widening the lithium-ion diffusion channel and improving ionic conductivity and rate performance. Modified SiO2 nanoparticles are coated on the surface of lithium iron phosphate using the sol-gel method to form a dense and chemically stable protective layer, which isolates it from contact with the electrolyte, reduces side reactions, and extends cycle life. Carbon nanotubes are used to coat lithium iron phosphate, reducing the overall resistance of the electrode, improving rate performance, providing a conductive path, and enhancing the electrochemical performance of the material.

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