Hard Carbon as Anodes for Potassium-Ion Batteries: Developments and Prospects

Potassium-ion batteries (PIBs) are regarded as a potential substitute for LIBs owing to the benefits of potassium’s abundance, low cost, and high safety. Nonetheless, the practical implementation of potassium-ion batteries still encounters numerous challenges, with the selection and design of anode materials standing out as a key factor impeding their progress. Hard carbon, characterized by its amorphous structure, high specific surface area, and well-developed pore structure, facilitates the insertion/extraction of potassium ions, demonstrating excellent rate performance and cycling stability. This review synthesizes the recent advancements in hard carbon materials utilized in PIB anodes, with a particular focus on the potassium storage mechanism, electrochemical properties, and modification strategies of hard carbon. Ultimately, we present a summary of the current challenges and future development directions of hard carbon materials, with the objective of providing a reference for the design and optimization of hard carbon materials for PIBs.