Construction of In4/3P2S6 nanosheets uniformly dispersed on rGO for enhanced sodium ion storage performance

The tendency of stacking of the layered ternary metal phosphorous chalcogenides into large blocky structures stemming from the van der Waals interaction leads to the sluggish ion migration and reduced reactive sites. Therefore, reducing the particle size and optimizing the structure of electrode materials are the critical to improve their ion storage. In this study, the optimized two-dimensional In4/3P2S6 nanosheets uniformly anchored on reduced graphene oxide (rGO) is constructed (In4/3P2S6/rGO) by adjusting the amount of introduced graphene oxide. The favorable reduced-sized structure and multicomponent property endow the In4/3P2S6/rGO composite with rich exposed reactive sites, shortened the ions/electrons diffusion distances, increased electrical conductivity, and suppressed structural change. Compared with the reference samples, the optimized In4/3P2S6/ rGO-60 exhibits faster reaction kinetics and remarkable sodium storage performance, maintaining a high capacity of 528 mA h g-1 at 5 A g-1 after 1000 cycles, as well as an outstanding rate property (364 mA h g-1 at 20 A g-1). Furthermore, the reaction mechanism consisting of sequential insertion, conversion, and alloying processes in In4/3P2S6/rGO-60 is elucidated by cyclic voltammetry, ex-situ X-ray photoelectron spectroscopy, and in- situ electrochemical impedance spectroscopy. This strategy can be extended to other metal phosphorous chalcogenides, providing a guidance in the design of advanced electrodes for constructing high-performance sodium- ion batteries.