FeP Coated in Nitrogen/Phosphorus Co-doped Carbon Shell Nanorods Arrays as High-Rate Capable Flexible Anode for K-ion Half/Full Batteries

Abstract

Building a proper flexible electrode with high cycling stability, rate capacity and initial coulombic efficiency (ICE) for flexible potassium-ion batteries (PIBs) remains a challenge. Herein, nitrogen/phosphorus co-doped carbon coated FeP nanorods arrays on carbon cloth (FeP@N, PC NRs/CC) as high-rate capable flexible self-supporting anode was successfully fabricated. The composite electrode combines the advantages of FeP nanorods arrays (FeP NRs), carbon cloth (CC) and N, P co-doped carbon shell (N, P–C), which comprehensively improves the electrochemical stability of the flexible electrode, while the open space between FeP nanorods can facilitate electrolyte impregnation and enhance K+ transfer, thus effectively elevating the corresponding rate capability. For the FeP@N, PC NRs/CC electrode, it delivers a reversible capacity of 388.8 mA h g−1 at 0.5 A g−1 up to 400 cycles. Even at 1.5 A g−1, it can still achieve a remarkable rate capacity of 346.9 mA h g−1. Moreover, the assembled soft-packed cell can always light the LED lights when it is bent at different angles, which exhibits excellent mechanical flexibility.