Coupling Ternary Selenide SnSb ₂ Se ₄ 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 SnSb 2 Se 4 nanoparticles (SnSb 2 Se 4 /GNS). In the product, fine monodisperse SnSb 2 Se 4 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 SnSb 2 Se 4 inherits the advantages of the binary Sb 2 Se 3 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 SnSb 2 Se 4 /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.