In-Situ growing tungsten Sulfide/Carbon nanosheets on sodium titanate nanorods to stabilize Surface-Structure for enhanced Sodium-ion storage

Abstract

Sodium-ions hybrid capacitors (SIHCs) have been recognized as one of the most potential energy storage devices, which can deliver high power and energy densities simultaneously. However, the sluggish kinetics of electrode materials severely restricts the performance of SIHCs. Herein, N, P-codoped carbon and WS2 nanosheets coating on sodium titanate nanorods (NTO@WS2/N, PC) were first designed by in-situ growing process and sulfuration treatment for boosting sodium-ion storage. Specifically, NTO@WS2/N, PC electrodes displayed a satisfactory specific capacity of 274.7 mAh g−1 at 3.0 A g−1 after 1200 cycles. Furthermore, as-assembled SIHCs delivered high-energy density of 112.1 Wh kg−1 and high-power density of 4334.4 W kg−1. Besides, long-term cycling test revealed that a remarkable capacity retention rate of 89.7% was obtained at 8.0 A g−1 after 2000 cycles. The excellent cycling stability and rate property could be ascribed to following aspects. On the one hand, N, P-codoped carbon could enhance the electrical conductivity and strengthen the structural integrality of the composites. On the other hand, ultrathin WS2 nanosheets and one-dimensional (1D) NTO nanorods structure were conducive to the rapid diffusion of Na+. This work provides a convenient technique to stabilize the structure of electrode materials, which can promote the practical application of SIHCs.