Introduction of a multifunctional percolated framework into Na metal for highly stable sodium metal batteries†

Abstract

Introducing highly sodiophilic skeletons is a highly efficient approach to mitigating the challenges of sodium metal anodes (SMAs). However, the limited functionality of skeletons and poor processability of bare sodium metal further obstruct the practical application of SMAs. Herein, a stable SMA with high processability is realized by introducing a percolated multi-functional NPC/Na₂Se framework throughout metallic Na using simple heating infusion and rolling/folding processes. This percolated framework provides mechanical strength to mitigate cracking and facilitates interconnected pathways for the rapid and even distribution of charges, reducing hotspots and promoting homogeneous Na deposition. Moreover, the Na₂Se in the NPC/Na₂Se framework produces a stable solid electrolyte interphase (SEI) for fast Na⁺ diffusion. At the same time, the NPC acts as a 3D matrix to confine the Na and buffer the huge volume change. Consequently, the modified Na@NPC/Na₂Se anode demonstrates excellent performance in both low-cost carbonate (1200 h at 1.0 mA cm⁻²) and ether-based (8000 h at 5.0 mA cm⁻²) electrolytes with high coulombic efficiency (99.89% after 200 h of plating/stripping). More remarkably, the Na@NPC/Na₂Se‖NVP full cell manifests unprecedented cycling (85 mA h g⁻¹ at 20C after 4000 cycles) and excellent rate capability (∼105 mA h g⁻¹ at 50C). This electrode featuring a multi-functional framework creates new opportunities for the development of SMAs and can be extended to anode free batteries.