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.

Layered materials with two-dimensional ion diffusion channels and fast kinetics are attractive as cathode materials for secondary batteries. However, one main challenge in potassium-ion batteries is the large ion size of K⁺, along with the strong K⁺−K⁺ electrostatic repulsion. This strong interaction results in initial K deficiency, greater voltage slope, and lower specific capacity between set voltage ranges for layered transition metal oxides. In this review, a comprehensive review of the latest advancements in layered cathode materials for potassium-ion batteries is presented. Except for layered transition metal oxides, some polyanionic compounds, chalcogenides, and organic materials with the layered structure are introduced separately. Furthermore, summary and personal perspectives on future optimization and structural design of layered cathode materials are constructively discussed. We strongly appeal to the further exploration of layered polyanionic compounds and have demonstrated a series of novel layered structures including layered K₃V₂(PO₄)₃.