Y. Zhang, Biao Zheng, Qingfeng Fu, Yan Duan, Aiping Hu, Wenbin Zhong, Jilei Liu
Porous carbon (PC) is widely used in energy storage devices such as supercapacitors due to its high surface area and abundant ion-accessible pores. However, its excessive open porosity in sodium-ion batteries (SIBs) leads to severe side reactions and low initial Coulombic efficiency. Regulating pore structures to transform PC into hard carbon (HC) with rich closed-pores is essential for improving sodium storage performance. Here, we report a direct microstructural conversion of PC into high-performance HC anodes for SIBs via the upcycling of polytetrafluoroethylene (PTFE) waste. Assisted by Brønsted-basic NH 3, the ultrastrong C–F bonds in PTFE are efficiently cleaved, inducing in situ carbon deposition that transforms open pores into a closed-pore structure with curved graphitic domains. The optimized YPT-1200 electrode achieves a high reversible capacity of 370.3 mAh g –1 with satisfactory initial Coulombic efficiency of 78.0% as well as impressive cycling stability (83.4% capacity retention over 300 cycles at 0.5C).