Ultrafast synthesis of hard carbon for high-rate and low-temperature sodium-ion storage through flash Joule heating

Developing effective strategies to promote the sodium-ion storage performance of hard carbon anodes is essential for its practical application in sodium-ion batteries. The carbonization process plays a crucial role in regulating the microstructure of hard carbon. Conventional carbonization methods of slow-heating have hit a bottleneck in structural controls of hard carbon materials. Herein, hard carbon with high-rate and low-temperature sodium storage capability is ultrafast synthesized by flash Joule heating. Compared to the hard carbon synthesized by conventional slow-heating, the hard carbon synthesized by flash Joule heating has smaller particle size, larger interlayer spacing, and larger closed-pores leading to superior performance. This work provides a simple and effective method of boosting sodium-ion storage performance for hard carbon materials.