Achieving Ultrahigh-Rate and Low-Temperature Sodium Storage of FePS via In Situ Construction of Graphitized Porous N-Doped Carbon.

Sodium-ion batteries (SIBs) have become an important supplementation to lithium-ion batteries. Unfortunately, the low capacity and inferior low-temperature performance of traditional hard carbon led to limited energy density and a range of applications of SIBs. Herein, we present high-performance SIBs via embedding FePS in graphitized porous N-doped carbon (FPS/GPNC) using coordination polymerization reaction. Such unique graphitized pores are in situ-constructed by the self-aggregation of Fe nanoparticles with high surface energy at high temperatures, which affords a three-dimensional open channel and a graphitized conductive network for fast transportation of Na and electrons. Moreover, an ingenious buffer barrier composed of graphitized pores is constructed for FePS to withstand volume fluctuation during cycling. Consequently, a superior capacity of 354.2 mAh g is delivered even when the rate increases to 50 A g. The impressing cycling lifespan up to 4700 cycles is achieved at 30 A g with excellent retention of 84.4%. Interestingly, the low-temperature performance (-20 °C) of FePS is explored for the first time, and excellent stability (502.6 mAh g maintained after 100 cycles at 0.1 A g) is obtained, indicating huge potential of practical application. This work provides insights into designing high-rate, high-capacity, and low-temperature SIBs.