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The major challenge faced by potassium-ion batteries (PIBs) lies in the shortage of high-performance and cost-effective electrode materials. Herein, we demonstrate a candied-haws structure containing FeS 2 @C core−shell units as an advanced anode for PIBs. This special material is featured with thin amorphous carbon as the shell, which can confine the active iron disulfide core during the (de)potassiation processes to maintain the structural integrity. Moreover, consecutive carbon nanofibers interconnect with each other to generate a high-performance three-dimensional conductive framework, contributing to attaining enhanced reaction kinetics. Consequently, when measured as an anode material for PIBs, the FeS 2 @C nanocomposite achieves a large reversible capacity of 292 mAh g −1 at 0.1 A g −1 after 300 cycles and a high-rate capacity of 183 mAh g −1 at 2 A g −1 .

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Potassium-ion batteries (PIBs) as energy storage devices show great development potential in the field of large-scale energy storage on account of their abundant potassium resources, rapid K+ mobility in electrolyte,...

Potassium manganese hexacyanoferrate shows great potential as a cathode material for potassium-ion batteries (PIBs) due to its impressive electrochemical performance, abundant elements, and easy synthesis. However, severe capacity fading and poor K+ diffusion kinetics greatly limit its large-scale application. Herein, we propose a facile anion exchange method to construct Mn–Ni Prussian blue analogue (denoted MnNi-PBA) spheres. The introduction of Ni can stabilize the structure to enhance the cycling performance, and rich active sites can be provided by the formation of a unique porous spherical structure, thus enabling shorter ion diffusion pathways during charge/discharge. Consequently, the MnNi-PBA sphere cathode delivers an initial discharge capacity of 130.6 mAh g–1 at 10 mA g–1, an enhanced rate capability of 66.3 mAh–1 at 200 mA g–1, and a long cycle life with 83.8% capacity retention after 500 cycles. When assembled with a pitch-derived soft carbon anode, a full cell exhibits excellent cycling stability and rate performance. In addition, ex situ X-ray diffraction demonstrates that the MnNi-PBA spheres undergo reversible structural changes (monoclinic ↔ cubic) throughout the cycling process. Therefore, this work may offer a design strategy to synthesize Mn-based Prussian blue analogues for the application of PIBs.