Hierarchical Porous Nanosheets Constructed by Graphene‐Coated, Interconnected TiO2 Nanoparticles for Ultrafast Sodium Storage

Abstract Sodium‐ion batteries (SIBs) are considered promising next‐generation energy storage devices. However, a lack of appropriate high‐performance anode materials has prevented further improvements. Here, a hierarchical porous hybrid nanosheet composed of interconnected uniform TiO 2 nanoparticles and nitrogen‐doped graphene layer networks (TiO 2 @NFG HPHNSs) that are synthesized using dual‐functional C 3 N 4 nanosheets as both the self‐sacrificing template and hybrid carbon source is reported. These HPHNSs deliver high reversible capacities of 146 mA h g −1 at 5 C for 8000 cycles, 129 mA h g −1 at 10 C for 20 000 cycles, and 116 mA h g −1 at 20 C for 10 000 cycles, as well as an ultrahigh rate capability up to 60 C with a capacity of 101 mA h g −1 . These results demonstrate the longest cyclabilities and best rate capability ever reported for TiO 2 ‐based anode materials for SIBs. The unprecedented sodium storage performance of the TiO 2 @NFG HPHNSs is due to their unique composition and hierarchical porous 2D structure.