Transformative Catalytic Carbon Conversion Enabling Superior Graphitization and Nanopore Engineering in Hard Carbon Anodes for Sodium‐Ion Batteries
Gui-Lai Zhang, Hong Gao, Dingyi Zhang, Jun Xiao, Limeng Sun, Jiayi Li, Congcong Li, Yiwen Sun, Xinyao Yuan, Peng Huang, Yi Xu, Xin Guo, Yufei Zhao, Yong Wang, Yao Xiao, Guoxiu Wang, Hao Liu
Abstract
ABSTRACT Hard carbons are promising anode materials for sodium‐ion batteries (SIBs), but they face challenges in balancing rate capability, specific capacity, and initial Coulombic efficiency (ICE). Direct pyrolysis of the precursor often fails to create a suitable structure for sodium‐ion storage. Molecular‐level control of graphitization with open channels for Na + ions is crucial for high‐performance hard carbon, whereas closed pores play a key role in improving the low‐voltage (< 0.1 V) plateau capacity of hard carbon anodes for SIBs. However, creation of these closed pores presents significant challenges. This work proposes a zinc gluconate‐assisted catalytic carbonization strategy to regulate graphitization and create numerous nanopores simultaneously. As the temperature increases, trace amounts of zinc remain as single atoms in the hard carbon, featuring a uniform coordination structure. This mitigates the risk of electrochemically irreversible sites and enhances sodium‐ion transport rates. The resulting hard carbon shows an excellent reversible capacity of 348.5 mAh g −1 at 30 mA g −1 and a high ICE of 92.84%. Furthermore, a sodium storage mechanism involving “adsorption–intercalation–pore filling” is elucidated, providing insights into the pore structure and dynamic pore‐filling process.