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 TiO₂ nanoparticles and nitrogen-doped graphene layer networks (TiO₂@NFG HPHNSs) that are synthesized using dual-functional C₃N₄ 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 TiO₂-based anode materials for SIBs. The unprecedented sodium storage performance of the TiO₂@NFG HPHNSs is due to their unique composition and hierarchical porous 2D structure.

The first synthesis of novel nitrogen-doped few-layered graphene-wrapped TiO₂ ­hierarchical porous hybrid ­nanosheets using dual-functional C₃N₄ sheets as both the sacrificial template and hybrid carbon source results in a high reversible ­capacity, unprecedented cycling ­stability, and excellent rate capability as anode materials for sodium-ion batteries due to their unique composition and ­hierarchical porous 2D structure.

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