Polymer derived mesoporous hard carbon nanospheres as high-performance anode materials for potassium-ion batteries

Potassium ion batteries (PIBs) have attracted considerable attention owing to their unique advantages. Nevertheless, the large radius of potassium ions and their sluggish kinetics hinder the further development of potassium ion batteries. In this study, mesoporous hard carbon nanospheres (PCN- x , where x corresponds to pyrolysis temperatures of 700 ℃, 800 ℃, and 900 ℃) have been successfully prepared from a facile hydrothermal and pyrolysis processes at different temperatures of phenolic resin precursor. The obtained PCN- x materials offer several advantages, including abundant active sites, favorable interlayer spacing (0.4113 nm), high specific surface area (574.720 2 m 2 g −1 ), and exceptional structural stability . These merits collectively contribute to enhancing the stability of potassium ion intercalation/deintercalation behavior and provide a high pseudocapacitive capacity. While used as anode materials for PIBs, these materials exhibit remarkable battery performance, including a superior initial charge capacity of 395.2 mAh g −1 at the current rate of 100 mA g −1 , exemplary rate performance (209 mAh g −1 at 5 A g −1 ), and outstanding cycle stability, retaining a capacity of 249 mAh g −1 after 1000 cycles. The present work introduces a low-cost and straightforward method for the preparation of anode materials of PIBs and provides valuable insights into the energy storage field.