Electrochemical Performance of Carbon Modified LiNiPO4as Li-Ion Battery Cathode: A Combined Experimental and Theoretical Study

This study demonstrates the synthesis of olivine LiNiPO(4)and carbon modified LiNiPO4(LNP/C-composites) cathode materials for use in lithium-ion batteries (LIBs) synthesized via non aqueous sol-gel process. The LNP/C-composites were fabricated through high energy ball-milling of LiNiPO(4)with different weight ratios of conductive carbon black. The electrochemical performance of LiNiPO(4)has been considerably improved by modifying the material with conductive carbon black which enhanced cathode performance as thoroughly studied by electrochemical analysis. Discharge capacities of LNP/C-composite cathodes with 25 wt% carbon were 175 mAh g(-1), 150 mAh g(-1)and 125 mAh g(-1)with corresponding capacity retention of 82.7%, 84.1% and 82.2% after 100 cycles at 0.05C, 0.1C and 1C rates, respectively. High-temperature electrochemical impedance spectra correspond to decreased charge transfer resistance with increased electronic conductivity and minimum cell polarization for the LNP/C powders. Additionally, the inflow of lithium-ion flux in cathode particle was simulated by using phase-field modeling indicating the coexistence of Li-poor and Li-rich phases during charging and discharging processes. The findings are significant for the development of optimal battery electrode materials as the methodology and insights used are readily transferable to other ion-insertion based electrodes.