The ever‐increasing demand for large‐scale energy storage systems requires novel battery technologies with low‐cost and sustainable properties. Due to earth‐abundance and cost effectiveness, the development of rechargeable potassium ion batteries (PIBs) has recently attracted much attention. Since carbon‐based materials are abundant, inexpensive, nontoxic, and safe, extensive feasibility investigations have suggested that they can become promising anode materials for PIBs. This review not only attempts to provide better understanding of the potassium storage mechanism, but also summarizes the availability of new carbon‐based materials and their electrochemical performance covering graphite, graphene, and hard carbon materials plus carbon‐based composites. Finally, the critical issues, challenges, and perspectives are discussed to demonstrate the developmental direction of PIBs.

3D hierarchically porous carbon/Sn composites is synthesized by in situ NaCl template method, which can effectively avoid the direct exposure of elemental Sn to the electrolyte, efficiently alleviate the volume expansion and exhibits good potassiation/depotassiation capacity.

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Early studies indicate that graphite is feasible as the negative electrode of a potassium-ion battery, but its electrochemical performance still cannot meet the demands of applications. More efforts should be focused on increasing the specific capacity and improving the rate capability in the meantime. Thus, stainless-steel autoclave technology has been utilized to prepare phosphorus nanoparticles encapsulated in reduced graphene oxide matrix as the electrode materials for a potassium-ion battery. As a result, the composite matrix affords high reversible capacities of 354 and 253 mA h g at 100 and 500 mA g , respectively. The superior electrochemical performance is mainly because the composite matrix possesses better electronic conductivity and a robust structure, which can promote the electron-transfer performance of the electrode. Furthermore, phosphorus particles can contribute to the high capacity through an alloying mechanism. In addition, the silklike, ultrathin, film composite with a high surface area is conducive to capacitive potassium-ion storage, which plays a more important role in rate performance and a high current density capability.

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Dealloying is a powerful technology to fabricate nanoporous materials with tunable structures and compositions for battery applications. Meanwhile, electrochemical dealloying is an intrinsic process for metal anodes that exhibits fundamental correlations with electrode morphologies and structures. In this work, Li‐Ag composites are fabricated as a case study to understand the spontaneous structural evolution and the in situ formation of nanoporosity during a reversible lithiation/delithiation process. The rationally designed nanoporous AgLi (NPAgLi) framework with limited Li capacity (10 mAh cm−2) enables a dendrite‐free anode with marginal volume variation upon long‐term cycling, which can be attributed to the spatially confined reaction pattern along with efficient Li alloying/dealloying. Furthermore, full cell tests reveal the NPAgLi anode remains stable under practical conditions such as lean electrolyte (15 µL), large areal capacity (1.6 mAh cm−2), and high‐loading cathode (12 mg cm−2). This work provides new perspectives on the in situ structural evolution of Li‐rich alloy electrodes and the results are expected to contribute to the development of alkali metal anodes.