Rapid mechanochemical synthesis of polyanionic cathode with improved electrochemical performance for Na-ion batteries.

Na-ion batteries have been considered promising candidates for stationary energy storage. However, their wide application is hindered by issues such as high cost and insufficient electrochemical performance, particularly for cathode materials. Here, we report a solvent-free mechanochemical protocol for the in-situ fabrication of sodium vanadium fluorophosphates. Benefiting from the nano-crystallization features and extra Na-storage sites achieved in the synthesis process, the as-prepared carbon-coated Na3(VOPO4)2F nanocomposite exhibits capacity of 142 mAh g−1 at 0.1C, higher than its theoretical capacity (130 mAh g−1). Moreover, a scaled synthesis with 2 kg of product was conducted and 26650-prototype cells were demonstrated to proof the electrochemical performance. We expect our findings to mark an important step in the industrial application of sodium vanadium fluorophosphates for Na-ion batteries. The high production cost and poor electrochemical performance of polyanionic cathode hinders their industrial application. Here, the authors report large-scale fabrication of sodium vanadium fluorophosphates and in situ construction of their carbon nanocomposites via a mechanochemical protocol.