Manipulating K‑Storage Mechanism of Soft Carbon via Molecular Design-Driven Structure Transformation

The emerging potassium-ion batteries (PIBs) have been placing stratospheric expectations for realizing grid-scale electrochemical storage of renewable energy. However, the unsatisfactory K-storage of PIB anode materials, especially promising carbonaceous materials, significantly limited the development of PIBs. Here, a molecular design strategy was proposed to realize controllable structure transformation of soft carbon (SC) materials for enhanced K-storage performance. The optimized SC-PCN material delivered a high reversible K-storage capacity of 838 mAh/g at 50 mA/g, outstanding rate capability (213 mAh/g at 1000 mA/g), and excellent long-term cycling performance (301 mAh/g maintained after 300 cycles at 500 mA/g), superior to most previously reported carbon-based PIB anodes materials. Reaction kinetic analysis revealed that the proposed molecular design strategy can achieve the transformation from a surface capacitive-dominated mechanism to a capacitive-diffusion hybrid mechanism for SC-PCN, benefiting from its unique microstructures with highly defective surface generated via the synergistic effect from template removal, N doping, and surface reconstruction. The optimal hybrid K-storage mechanism should be responsible for the excellent K-storage properties of the prepared SC-PCN

Structure Manipulation of C₁N₁‑Derived N‑Doped Defective Carbon Nanosheets to Significantly Boost K‑Storage Performance

Nanocarbon materials demonstrated huge advantages for K-storage applications due to their wide range of structural tunabilities. However, their K-storage performance was still limited by the underutilization of disordered and ordered carbon structures simultaneously. Here, we developed a C1N1-based reconstruction strategy to fabricate N-doped defective carbon nanosheet (NdC) materials for K-storage. The disordered carbon defects and ordered carbon interlayers were well balanced via choosing suitable precursors for self-condensation generation of the C1N1 skeleton as well as subsequently regulating the high-temperature reconstruction process, resulting in a significantly enhanced intercalation-adsorption K-storage mechanism. As a result, the optimized G-NdC materials delivered a high reversible discharging capacity of 620 mA h/g at 50 mA/g and 241 mA h/g even at 1000 mA/g as well as 210 mA h/g after 300 cycles at 500 mA/g. These excellent K-storage properties should be ascribed to the unique order–disorder balanced microstructures with fast surface capacitive-controlled reaction kinetics. This study emphasized the important roles of carbon defects in the K-storage process and provides a deep insight into the understanding of nanocarbon-based K-storage mechanisms