Correlation of Electrochemical Performance with Lithium Environments and Cation Dynamics in Li2(Mn1–y Fe y )P2O7 using 6Li Solid-State NMR

6Li solid-state nuclear magnetic resonance (ssNMR) is used here to evaluate a series of Li2Mn1–y Fe y P2O7 cathode materials in an effort to quantify ion exchange rates and diffusion pathways. Magic angle spinning (MAS) NMR of the series of mixed metal pyrophosphates reveals a trade-off between electrochemical performance and well-resolved NMR spectra resulting from the change in electronic structure of the transition metal redox center. In …