Enhancing the Low‐Temperature Performance of Sodium‐Ion Battery by Introducing Nanodiamonds in Anode Prepared from Cattail Grass

Abstract Sodium‐ion batteries (SIBs) have received much attention as ideal candidates for next‐generation large‐scale energy storage systems, but their performance significantly deteriorates at low temperatures, limiting their application in cold or high‐altitude environments. This work presents an easier approach to improving low‐temperature performance by incorporating nanodiamonds (NDs) into hard carbon anodes derived from cattail grass. The modified anode shows a larger specific surface area, offering more active sites for Na + . After 90 cycles at 0.1 A g −1 , the reversible capacity of the modified anode reaches 365.1 mA h g −1 at room temperature and remains 245.1 mA h g −1 at −40 °C. Even under a high current density of 1.0 A g −1 , it delivered 108.2 mA h g −1 after 500 cycles with a capacity retention rate of 90%. The improved low‐temperature performance is attributed to the introduced NDs in SIBs, which in crease the number of the reversible active sites, reduce charge transfer resistance, lower activation energy, and effectively inhibit the formation of Na dendrites. This work presents a potential pathway into designing efficient and stable anode materials for SIBs at low temperatures.