A high-performance solid sodium battery enabled by a thin Na-Ti3C2Tx composite anode

Low-cost sodium metal batteries are expected to be used as an effective supplement to lithium-ion batteries in the energy storage field in the future, and have made great progress in recent years. However, the safety issues caused by Na dendrites and the relatively low specific capacity of sodium metal batteries are obstacles to their further commercialization. In this work, a thin Na-Ti3C2Tx composite anode was prepared. The thickness of the composite anode Na-Ti3C2Tx is only 46% of that of pure sodium, greatly reducing costs and increasing energy density. In addition, the nucleation overpotential of Na-Ti3C2Tx is 55.2% and 56% that of Na at 0.5 mA cm−2 and 2 mA cm−2 respectively, which indicates that the composite anode reduces the sodium nucleation barrier and is favorable for sodium deposition. Furthermore, the poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and Na3Zr2Si2PO12 modified polyimide membrane significantly enhances the mechanical strength and sodium ion migration and promoted the deposition and stripping of metallic sodium. The sodium battery with the composite metal sodium anode and PVDF-HFP-Na3Zr2Si2PO12 modified polyimide membrane has a specific discharge capacity of 87.9 mAh g−1, and the capacity retention rate is close to 100% without significant fluctuation after 500 cycles.