Stability Enhancement of Hard Carbon Anode Materials in Sodium-Ion Batteries through Controllable Oxygen-Doped Pitch Coating.

Biomass-derived hard carbon (HC) materials, celebrated for their superior sodium storage capability and economic viability, have emerged as a promising candidate for anode materials in sodium-ion batteries (SIBs). However, the electronic conductivity, cycling stability, and initial Coulombic efficiency (ICE) of HC materials remain significant challenges hindering their broader application. In this study, we successfully developed a HC anode material using Indian trumpetflower seeds (ITS) as precursors, enhanced by coating with pitch on their surface. This ITS-based HC material not only delivers an impressive reversible capacity of 430.3 mAh g @ 300 mA g but also maintains a capacity retention of 63% at a current density of 1500 mA g, along with a remarkable ICE of 90.92%. After 900 cycles, the capacity retention remains high at 77%, demonstrating exceptional cycling stability. These performance enhancements are attributed to the appropriate concentration of carbonized oxygen-doped pitch (CODP) coating, which avoids direct contact between the electrolyte and ITS and introduces oxygen atoms to provide more active sites. This work not only provides a promising precursor for the fabrication of high-performance HC anodes for SIBs but also introduces an innovative synthetic strategy, injecting momentum into the commercialization process of SIBs.