Coupling Space Charge Storage With Alloying Reactions Anode for Ultrafast and High Energy Storage

ABSTRACT Achieving the dual objectives of high‐energy‐density and high‐power‐density within a single electrode has long been regarded as the “holy grail” for lithium‐ion batteries. Herein, a mixed electronic/ionic/alloy conductor material (Fe/Li 2 O‐Sn) is successfully developed to address this challenge by coupling the space charge storage mechanism with alloying reaction. The strong affinity and abundant interfaces between the metallic iron and the Li 2 O facilitates ultrafast lithium‐ion diffusion throughout the electrode. By the mixed electronic and ionic conducting networks, the alloying reaction of tin (Sn) not only demonstrates ultrafast reaction kinetics but also fully utilizes its high theoretical capacity. Benefiting from the unique structure, the Fe/Li 2 O‐Sn electrode delivers an outstanding electrochemical performance, including an ultrafast charging/discharging rate of 40 A g − 1 , a high‐energy‐density of 1242 Wh kg −1 , and an exceptional cycling ability of over 20,000 cycles. This synergistic integration of the space charge effect with alloying reactions in anode materials holds significant potential for the development of lithium‐ion batteries with high energy‐density, high power‐density and long‐term cycling stability.