In-Situ Implanted Robust and Durable Cathode-Electrolyte Interphase for High-Performance Sodium-Based Dual-Ion Batteries

The practical applications of economically viable and environmentally friendly sodium-based dual-ion batteries (Na-DIBs) are currently restricted because of the short life spans of these systems. The development of a robust and durable cathode–electrolyte interphase (CEI) layer is expected to serve as an effective measure to enhance the cycling performances of Na-DIBs. Herein, a high charging voltage is employed during precycling to decompose sodium difluoro(oxalato)borate (NaDFOB) on an expanded mesocarbon microbead (HRO-MCMB) cathode surface, thereby promoting the formation of an inorganic-rich CEI layer. This CEI layer not only serves as a chemically stable and mechanically strong barrier but also effectively inhibits the volume expansion and exfoliation of the cathode graphite layer. Consequently, the HRO-MCMB cathode modified with 0.02 M NaDFOB exhibited a capacity retention of 97.0% after 1000 cycles at a current density of 1 C. The HRO-MCMB(+)||HC(−) (HC = hard carbon) full cell maintained a specific capacity of 110.9 mAh g–1 after 300 cycles at 1 C. Furthermore, the Na-DIB full cell exhibited an impressive energy density of up to 422.6 Wh kg–1, and its maximum power density reached 4682.9 W kg–1. Overall, this study provides a novel strategy for the practical development of high-performance Na-DIBs.