Fe–P networks and the Li insertion extraction induced electrochemical performance in LiFePO\(_{4}\) cathode materials

This study reclassifies Fe–P network types in the LiFePO \(_{4}\) ${}_4$ structure and comprehensively analyzes their associated electrochemical properties. Six low-energy Fe–P networks were examined for variations in energy, voltage, volume, and charge across Li compositions from 0 to 1. We calculated the relative formation energy for each network and identified stable components to determine the voltage platform. Most structures align with the ground state, FePO \(_{4}\) ${}_4$ /LiFePO \(_{4}\) ${}_4$ two-phase configuration. Notably, certain Fe–P networks (FY, AC \(^{'}\) ${}^{{}^{\prime }}$ , and a subset of AA \(^{'}\) ${}^{{}^{\prime }}$ ) exhibit stability in Li \(_{x}\) ${}_x$ FePO \(_{4}\) ${}_4$ ( \(\varvec{0}<\varvec{x}<\varvec{1}\) $\mathbf{0}<\mathit{x}<\mathbf{1}$ ), causing a distinct voltage platform jump during charge and discharge. Volume change analysis reveals comparable trends among similar Fe–P network structures. Charge changes in FePO \(_{4}\) ${}_4$ /LiFePO \(_{4}\) ${}_4$ are primarily element-dependent rather than Fe–P network-dependent. Our findings suggest the potential design of new structures with improved electrochemical performance for specific Fe–P network types.