Graphene wrapped TiO2@MoSe2 nano-microspheres with sandwich structure for high-performance sodium-ion hybrid capacitor

• A novel pea-pod-like TiO 2 @MoSe 2 /RGO composite was built. • A secondary substrate was constructed and the synergistic effect was used. • The strong interfacial coupling was realized through chemical bonds formation. • A high specific capacity of ∼ 446 mAh g -1 with CE ∼ 90% was achieved. Sodium-ion hybrid capacitors (SIHCs) have received extensive attention and research due to their combined advantages of high power performance and high energy density. However, the lack of high-performance anode materials has been a challenge for sodium storage devices. Herein, a heteroatom co-doped hollow spherical TiO 2 @MoSe 2 /reduced graphene oxide (RGO) with pea pods structure is designed and synthesized. This unique composite is made of TiO 2 as the stable framework, MoSe 2 sheet as the main active materials, and RGO conductive network as the protective cover. The sandwich structure provides stable and ordered transport channels for electrons and Na + , and greatly increases the number of active sites. As a result, TiO 2 @MoSe 2 /RGO exhibits satisfactory electrochemical performance. At a high current density of 2 A g -1 , TiO 2 @MoSe 2 /RGO still maintains a capacity of 106 mAh g -1 after 1000 cycles. The hybrid device possesses an energy density of 135 Wh kg −1 at power density of 1667 W kg −1 , demonstrating the design concept of heterogeneous composite provides a new route for the development of electrode materials in sodium-ion storage devices.