Synergistically enhanced K–Se and K–Sn storage reaction in multidimensional carbon structure

K–Sn and K–Se batteries are expected to simultaneously realize synergistic reactions in a single electrode with high capacity and stability of energy storage performance. However, the difficulty of these reactions is realizing the stable storage of K–Sn and the redox reaction of Se in the electrode simultaneously. Therefore, it is expected to design a new electrode structure to solve the above problems. Herein, a multidimensional structure of SnSe is designed with enhanced performance. In this structure, SnSe nanoparticles are co-encapsulated by "inner" 3D graphene aerogel and "outer" nitrogen doped carbon (SnSe/3D RGO@NC). The "outer" nitrogen doped carbon could provide stronger reaction product adsorption affinity as well as improve the potassium energy storage. The "inner" and "outer" carbon materials could synergistically improve the electrical conductivity, promoting the redox kinetics of Se to achieve K–Se energy storage. Ex-situ test results indicate K–Sn reaction and the redox reaction of Se were formed in the electrode. Finally, this electrode provides excellent potassium storage reversibility (312 mAh·g−1 after 350 cycles with 0.016% capacity fading per cycle) and favorable rate (196 mAh·g−1 at 5 A g−1) with K–Sn and K–Se reaction process. This study could provide ideas for structural design to utilize synergistic reactions with enhanced electrochemical performance in individual battery system.