Enabling intercalation‐type TiNb24O62 anode for sodium‐ and potassium‐ion batteries via a synergetic strategy of oxygen vacancy and carbon incorporation

Abstract

AbstractThe key to develop earth‐abundant energy storage technologies sodium‐ and potassium‐ion batteries (SIBs and PIBs) is to identify low‐cost electrode materials that allow fast and reversible Na+/K+ intercalation. Here, we report an intercalation‐type material TiNb24O62 as a versatile anode for SIBs and PIBs, via a synergistic strategy of oxygen vacancy and carbon incorporation to enhance ion and electron diffusion. The TiNb24O62−x/reduced graphene oxide (rGO) composite anode delivers high reversible capacities (130 mA h g−1 for SIBs and 178 mA h g−1 for PIBs), great rate performance (54 mA h g−1 for SIBs and 37 mA h g−1 for PIBs at 1 A g−1), and superior cycle stability (73.7% after 500 cycles for SIBs and 84% after 300 cycles for PIBs). The performance is among the best results of intercalation‐type metal oxide anodes for SIBs and PIBs. The better performance of TiNb24O62−x/rGO in SIBs than PIBs is due to the better reaction kinetics of the former. Moreover, mechanistic study confirms that the redox activity of Nb4+/5+ is responsible for the reversible intercalation of Na+/K+. Our results suggest that TiNb24O62−x/rGO is a promising anode for SIBs and PIBs and may stimulate further research on intercalation‐type compounds as candidate anodes for large ion batteries.