Hierarchical Encapsulation and Rich sp2 N Assist Sb2Se3-Based Conversion-Alloying Anode for Long-Life Sodium- and Potassium-ion Storage
Energy and Environmental Materials
Sodium- and potassium-ion batteries (SIBs and PIBs) have exhibited great application potential in grid-scale energy storage due to the abundant natural resources of Na and K. Conversion-alloying anodes with high theoretical capacity and low-operating voltage are ideal option for SIBs and PIBs but suffer the tremendous volume variations. Herein, a hierarchically structural design and sp2 N-doping assist a conversion-alloying material, Sb2Se3, to achieve superior life span more than 1000 cycles. It is confirmed that the Sb2Se3 evolves into nano grains that absorb on the sp2 N sites and in-situ form chemical bonding of C-N-Sb after initial discharge. Simulation results indicate that sp2 N has more robust interaction with Sb and stronger adsorption capacities to Na+ and K+ than that of sp3 N, which contributes to the durable cycling ability and high electrochemical activity, respectively. The ex-situ TEM and XPS results suggest that the Sb2Se3 electrode experiences conversion-alloying dual-mechanisms based on 12-electron transfer per formula unit.
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