A High-Performance Alloy-Based Anode Enabled by Surface and Interface Engineering for Wide-Temperature Sodium-Ion Batteries

Abstract

Alloy-based anodes have shown great potential to be applied in sodium-ion batteries (SIBs) due to their high theoretical capacities, suitable working potential, and abundant earth reserves. However, their practical applications are severely impeded by large volume expansion, unstable solid-electrolyte interfaces (SEI), and sluggish reaction kinetics during cycling. Herein, a surface engineering of tin nanorods via N-doped carbon layers (Sn@NC) and an interface engineering strategy to improve the electrochemical performance in SIBs are reported. In particular, the authors demonstrate that uniform surface modification can effectively facilitate electron and sodium transport kinetics, confine alloy pulverization, and simultaneously synergize interactions with the ether-based electrolyte to form a robust organic-inorganic SEI. Moreover, it is discovered that the diethylene glycol dimethyl ether electrolyte with strong stability and an optimized Na+ solvation structure can co-embed the carbon layer to achieve fast reaction kinetics. Consequently, Sn@NC anodes deliver extra-long cycling stability of more than 10 000 cycles. The full cell of Na3V2(PO4)3║Sn@NC exhibits high energy density (215 Wh kg−1), excellent high-rate capability (reaches 80% capacity in 2 min), and long cycle life over a wide temperature range of −20 to 50 °C.