Lithium Difluoro(Oxalate)Borate-Induced Interphase for High-Voltage LiFe0.15Co0.85PO4@C Cathode by Solid-State Synthesis

Herein, the effect of lithium difluoro(oxalate)borate (LiDFOB) as an electrolyte additive on the electrochemical performance of LiFe0.15Co0.85PO4@C (LFCP@C) cathode, synthesized by a scalable solid-state synthesis method is reported. Galvanostatic studies revealed better electrochemical performance among the LFCP@C (LiDFOB: 0.5-2 wt%) in a half-cell assembly compared to the LiFe0.15Co0.85PO4 in the absence of LiDFOB. Also, among the various concentrations of LiDFOB, the LFCP@C (LiDFOB-1.5 wt%) and LFCP@C (LiDFOB-2 wt%) are optimized as suitable candidates for further electrochemical studies owing to the high discharge capacities of 116 and 118 mAh g(-1). In addition, the electrochemical impedance studies (EIS) exhibited an increase in the charge-transfer resistance (R (ct)) as the amount of LiDFOB was increased, whereas a lower R (ct) value is observed in the absence of additive. In addition, the diffusion coefficient calculation is calculated using the EIS data, which shows a diffusion coefficient in the order of approximate to 10(-13) cm(2) s(-1). However, as the amount of LiDFOB is increased from 0 to 2 wt%, a decrease in the diffusion coefficient is observed owing to the formation of a stable and thicker passivation layer.