Na_3.5(MnVFeTi)_0.5(PO₄)₃: A Multi‐Transition‐Metal‐Ion‐Engineered NASICON‐Type Cathodes for Sodium Ion Batteries

Abstract

Electrochemically active Na‐superconductor (NASICON)‐type cathodes have the structural flexibility to include various transition elements, thus enabling high power outputs benefited by multi‐electron redox reactions. This study amalgamated multiple transition metal ions to construct a new NASICON‐type cathode i.e., carbon coated Na3.5(MnVFeTi)0.5(PO4)3 (NMVFTP/C), for Na‐ion batteries (NIBs). The NMVFTP/C cathode engineered in this study demonstrated stable Na+‐storage capacity, including long‐term cycling stability up to 4000 cycles at 3000 mA g‐1 with 96% capacity retention and a high‐rate output capacity of 86.78 mAh g‐1 at 2500 mA g‐1. To elucidate the ion transport process within the cathode, density functional theory modeling was employed. The low energy barrier for the diffusion of Na+ in the NMVFTP/C materials was proved to be a key factor supporting our material’s superior electrochemical performances.