Dense SnS2 nanoplates vertically anchored on a graphene aerogel for pseudocapacitive sodium storage

Two-dimensional (2D) heterostructures that combine advantages of individual components and overcome the associated drawbacks show great prospects for electrochemical energy storage. However, the prevailing layer-by-layer horizontal 2D stacks with tortuous and lengthy ion transport paths dramatically slow the reaction kinetics. Herein, we reported a 2D heterostructure with dense SnS2 nanoplates uniformly and vertically anchored on a graphene aerogel (SnS2@GA) for high-performance sodium-ion batteries. A SnS2 loading of 68 wt% without aggregation was achieved in the vertically aligned heterostructure via a controlled self-assembly process at low temperature, followed by an optimized in situ sulfidation treatment. The GA skeleton with interconnected pores effectively facilitates electron transfer, improves electrolyte wettability, and accommodates the volume expansion of SnS2 upon sodiation. The SnS2 is extensively exposed because of its 2D morphology and ion-accessible vertical channels. By synergizing these characteristics with the robust heterointerface, the composite exhibits boosted electrochemical reaction kinetics based on the pseudocapacitance-dominated charge storage mechanism and enhanced structural stability. As a result, the SnS2@GA anode delivers a high reversible capacity of 690 mA h g(-1) at 0.2 A g(-1), superior rate performance (492 mA h g(-1) at 4 A g(-1)) and long cycle life with 83% capacity retention after 1000 cycles.

Automated summary

The 2D heterostructure of vertically aligned SnS2 nanoplates anchored on a graphene aerogel shows high performance in sodium-ion batteries, with excellent rate capability and long cycling stability. The unique structure effectively addresses the issue of long and tortuous ion transport paths in traditional horizontal structures, leading to boosted electrochemical reaction kinetics and enhanced structural stability.