Influences of the surfactant on the performance of nano-LiMn2O4 cathode material for lithium-ion battery

Abstract

This study synthesized spinel LiMn2O4 materials using a solid-state reaction processing technology. Neutral surfactants and the tri-block copolymer P123 (template) formed an organic self-assembly in alcohol (solvent), with LiCH3COO·2H2O and Mn(CH3COO)2·4H2O as precursors of the inorganic skeleton. Changes in the structure, particle size, and surface area of LiMn2O4 powder in relation to different surfactant contents were investigated. The changes in surface area should affect the wetting effect of the electrolyte on the cathode material, thereby further influencing the actual reaction area and charge–discharge efficiency. The results were analyzed to assess the effect of surface area on electrochemical performance of LiMn2O4 cathode materials. X-ray diffraction (XRD) analysis data showed that LiMn2O4 materials synthesized through the solid-phase reaction method are single-phase spinel, whose original structure is unaffected by the addition of surfactants. Scanning electron microscopic (SEM) observation revealed that LiMn2O4 forms different spherical particles after the addition of different concentrations of surfactants. Furthermore, Brunauer–Emmett–Teller (BET) analysis showed that specific surface areas of 0.4–1.2m2/g are relatively effective in enhancing the capacitance, similarly the formation of spherical particles is beneficial in enhancing the capacitance, and the high-current discharge efficiency is similar to the low-current discharge efficiency. As for the different concentrations of P123, the experiments added with 1.42M P123 achieved optimum results.