Unlocking iron metal as a cathode for sustainable Li-ion batteries by an anion solid solution
Mingliang Yu, Jing Wang, Ming Lei, Min Soo Jung, Zengqing Zhuo, Yufei Yang, X. R. Zheng, Sean K. Sandstrom, Chunsheng Wang, Wanli Yang, De‐en Jiang, Tongchao Liu, Xiulei Ji
Abstract
Traditional cathode chemistry of Li-ion batteries relies on the transport of Li-ions within the solid structures, with the transition metal ions and anions acting as the static components. Here, we demonstrate that a solid solution of F − and PO 4 3− facilitates the reversible conversion of a fine mixture of iron powder, LiF, and Li 3 PO 4 into iron salts. Notably, in its fully lithiated state, we use commercial iron metal powder in this cathode, departing from electrodes that begin with iron salts, such as FeF 3 . Our results show that Fe-cations and anions of F − and PO 4 3− act as charge carriers in addition to Li-ions during the conversion from iron metal to a solid solution of iron salts. This composite electrode delivers a reversible capacity of up to 368 mAh/g and a specific energy of 940 Wh/kg. Our study underscores the potential of amorphous composites comprising lithium salts as high-energy battery electrodes.