Improving the Battery Metrics of Commercial Hard Carbon through S-Doping for Sodium-Ion Batteries

Hard carbon (HC) is now the leading choice for the anode in Sodium-ion Batteries (SIBs) because of its low operating voltage, high reversible capacity, and the wide range of inexpensive materials that may be used to synthesize it. The primary concern in commercial HCs is the initial Coulombic efficiency (ICE) and rate capability [1-2]. Hard carbon (HC) can exhibit a wide range of microstructures, morphologies, surface areas (including different types of pores), and porosities. These characteristics are determined by the carbon-rich material employed during synthesis and significantly impact the methods by which sodium ions are stored in HCs [3]. This study presents a novel structure of S-doped hard carbon derived from commercial HC. The sulfur-doped hard carbon material exhibits 67% ICE and maintains 94% of its capacity after undergoing 500 cycles at a rate of 300 mA/g (Fig.1). The sodium-ion storage mechanism of the S-doped HC material is analyzed using ex-situ Raman, XRD, SEM, EPR, and XPS techniques. These post-treated HC are compared with available commercial HC as anodes in sodium-ion batteries (SIBs) for a state-of-the-art evaluation of the battery metrics. References: A. Vasileiadis, Y. Li, Y. Lu, Y. S. Hu, and M. Wagemaker, ACS Appl. Energy Mater. , 6 , 127–140 (2023). Nagmani, Manna, S., & Puravankara, S., Chemical Communications , 60 (22), 3071-3074 (2024). S. You, Q. Deng, Q. Zhang, K. Huang, and C. Yang, ACS Sustain. Chem. Eng. , 11 , 10590–10597 (2023). Figure 1