摘要
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.
基金
supported by the National Natural Science Foundation of China(22209103)
Science and Technology Commission of Shanghai Municipality(22010500400)
Australian Research Council(FT180100705)。
