Coupling Ternary Selenide SnSb₂Se₄ with Graphene Nanosheets for High-Performance Potassium-Ion Batteries

Although chalcogenide anodes possess higher potassium storage capacity than intercalated-based graphite, their drastic volume change and the irreversible electrochemical reactions still hinder the effective electron/ion transfer during the potassiation/depotassiation process. To solve the above problems, this article proposes the synthesis of a lamellar nanostructure where graphene nanosheets are embedded with SnSb₂Se₄ nanoparticles (SnSb₂Se₄/GNS). In the product, fine monodisperse SnSb₂Se₄ nanoparticles are coupled with graphene nanosheets to form a porous network framework, which can effectively mitigate the drastic volume changes during electrode reactions and guarantee efficient potassium-ion storage through the synergistic interactions among multiple elements. Various electrochemical analyses prove that SnSb₂Se₄ inherits the advantages of the binary Sb₂Se₃ and SnSe while avoiding their disadvantages, confirming the synergistic effect of the ternary–chalcogenide system. When tested for potassium storage, the obtained composite delivers a high specific capacity of 368.5 mAh g⁻¹ at 100 mA g⁻¹ and a stable cycle performance of 265.8 mAh g⁻¹ at 500 mA g⁻¹ over 500 cycles. Additionally, the potassium iron hexacyanoferrate cathode and the SnSb₂Se₄/GNS anode are paired to fabricate the potassium-ion full cell, which shows excellent cyclic stability. In conclusion, this strategy employs atomic doping and interface interaction, which provides new insights for the design of high-rate electrode materials.