•Targeted surface modification on Li2CoPO4F with nano-SiO2 was fabricated.•Nano-SiO2 preferentially nestled up along the borders and boundaries.•SiO2 is bonded to the surface of Li2CoPO4F tightly during cycling.•The modification procedure has no influence on the heat sensitive core material.•The selectively modified Li2CoPO4F exhibits superior electrochemical performances.Tuning whole/partial surface modification on cathode material with oxide material is a sought-after method to enhance the electrochemical performance in power storage field. Herein, nano-SiO2 targeted partial surface modified high voltage cathode material Li2CoPO4F has been successfully fabricated via a facile self-assembly process in silica dispersion at ambient temperature. With the aid of polar -OH groups attracted on the surface of SiO2 micelles, the nano-SiO2 preferentially nestle up along the borders and boundaries of Li2CoPO4F particles, where protection should be deployed with emphasis against the undesirable interactions between materials and electrolytes. Compared with pristine Li2CoPO4F, the SiO2 selectively modified Li2CoPO4F cathode materials, especially LCPF-3S, exhibit desirable electrochemical performances with higher discharge capacity, more outstanding cycle stability and favorable rate capability without any additional carbon involved. The greatly enhanced electrochemical properties can be attributed to the improved lithium-ion diffusion kinetics and structure tolerance during repeated lithiation/delithiation process. Such findings reveal a great potential of nano-SiO2 modified Li2CoPO4F as high energy cathode material for lithium ion batteries.Download high-res image (259KB)Download full-size image

High-voltage cathode material LiNi0.5Mn1.5O4 has been prepared with a novel organic coprecipitation route. The as-prepared sample was compared with samples produced through traditional solid state method and hydroxide coprecipitation method. The morphology was observed by scanning electron microscopy, and the spinel structures were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. Besides the ordered/disordered distribution of Ni/Mn on octahedral sites, the confusion between Li and transition metal is pointed out to be another important factor responsible for the corresponding performance, which is worthy further investigation. Galvanostatic cycles, cyclic voltammetry, and electrochemical impedance spectroscopy are employed to characterize the electrochemical properties. The organic coprecipitation route produced sample shows superior rate capability and stable structure during cycling.Keywords: cathode material; high voltage; LiNi0.5Mn1.5O4; organic coprecipitation; spinel;