Sodium-ion capacitors can potentially combine the virtues of high power capability of conventional electrochemical capacitors and high energy density of batteries. However, the lack of high-performance electrode materials has been the major challenge of sodium-based energy storage devices. In this work, we report a microwave-assisted synthesis of single-crystal-like anatase TiO mesocages anchored on graphene as a sodium storage material. The architecture of the nanocomposite results in pseudocapacitive charge storage behavior with fast kinetics, high reversibility, and negligible degradation to the micro/nanostructure. The nanocomposite delivers a high capacity of 268 mAh g at 0.2 C, which remains 126 mAh g at 10 C for over 18 000 cycles. Coupling with a carbon-based cathode, a full cell of sodium-ion capacitor successfully demonstrates a high energy density of 64.2 Wh kg at 56.3 W kg and 25.8 Wh kg at 1357 W kg, as well as an ultralong lifespan of 10 000 cycles with over 90% of capacity retention.

Biomass-derived carbon materials have received extensive attention as electrode materials for energy storage devices, including electrochemical capacitors, lithium–sulfur batteries, lithium-ion batteries, and sodium-ion batteries.

Biomass-derived porous carbon material with sulfur and nitrogen dual-doping exhibits great potential for energy storage devices.

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This feature article reviews the recent progress of Li–S batteries to advance their practical uses.