“One stone two birds” design for hollow spherical Na4Fe3(PO4)2P2O7/C cathode enabled high‐performance sodium‐ion batteries from iron rust

Abstract

AbstractSodium‐ion battery (SIB) is considered as a revolutionary technology toward large‐scale energy storage applications. Developing cost‐effective cathode material as well as economical synthesis procedure is a key challenge for its commercialization. Herein, we develop a facile and economic strategy to simultaneously remove rust from the surface of carbon steel and achieve porous and hollow spherical Na4Fe3(PO4)2P2O7/C (HS‐NFPP/C). Benefiting from the desirable structure that fastens the electronic/ionic transportation and effectively accommodates the volume expansion/contraction during discharge/charge process, the as‐prepared cathode exhibits outstanding rate capability and ultralong cycle life. An extraordinarily high‐power density of 32.3 kW kg−1 with an ultrahigh capacity retention of 89.7% after 10 000 cycles are achieved. More significantly, the 3 Ah HC||HS‐NFPP/C full battery manifests impressive cycling stability. Therefore, this work provides an economical and sustainable approach for the massive production of high‐performance Na4Fe3(PO4)2P2O7 cathode, which can be potentially commercialized toward SIB applications.image