Modification of mixed-nitrogen anions configuration for accelerating lithium ions transport in the LiFePO4 electrode

Abstract

Olivine-type LiFePO₄ (LFP) is considered a promising cathode material for lithium-ion batteries (LIBs) owing to its abundance, high specific capacity, and cycling performance. However, its poor electronic and ionic transportation properties degrade the high rate capability, which limits its use in high-energy-density LIBs for applications such as electric vehicles. Therefore, in this study, we propose a modification of the anion configuration through nitrogen substitution using ion implantation to improve electronic and ionic transport during lithiation/delithiation. We found that nitrogen substitution at the oxygen sites effectively improved the electrochemical properties through surface modification and charge-transfer kinetics. In particular, the increased amount of nitrogen substitution at the surface regions resulted in reduced ionic and electronic resistances. These modified characteristics led to a remarkable rate capability with a high capacity (128.2 mA h g⁻¹ at 10C). We expect that these modified anion effects on the electrochemical properties can be effective in the design of cathode materials for LIBs.