Enhanced Electrochemical Performance of the LiNi0.5Mn1.5O4 Cathode Material by the Construction of Uniform Lithium Silicate Nanoshells

In order to alleviate the rapid capacity decay caused by the instability of the crystal structure and electrode/electrolyte interface, a series of Li2SiO3-coated LiNi0.5Mn1.5O4 materials have been prepared via the lithium acetate-assisted sol-gel method followed by a short-term calcination process. During the sol-gel process, TEOS is hydrolyzed, condensed, and polymerized with the assistance of lithium acetate to form a Li+-embedded [Si-O-Si]n network structure to ensure the uniformity of the coating. By changing the amount of TEOS and lithium acetate, the coating thickness can be precisely controlled, whose effects on the structural and electrochemical properties of LiNi0.5Mn1.5O4 materials are intensively investigated. The results show that the material with an appropriate thickness of Li2SiO3 coating exhibits a larger primary particle size and reduced secondary particle agglomeration. The uniform Li2SiO3 coating with appropriate thickness can not only improve Li+ ion diffusion kinetics but also suppress side reactions and CEI growth at the electrode/electrolyte interface. Besides, the interaction of Li2SiO3 with HF can alleviate electrode corrosion and the dissolution of transition metal ions. All the abovementioned factors together promote the significant improvement of the electrochemical performance of Li2SiO3-coated LiNi0.5Mn1.5O4 materials.