Unraveling the Charge Storage and Activity‐Enhancing Mechanisms of Zn‐Doping Perovskite Fluorides and Engineering the Electrodes and Electrolytes for Wide‐Temperature Aqueous Supercabatteries

Abstract

Abstract Herein, a trimetallic Ni–Co–Zn perovskite fluoride (ABF 3 ) (denoted as KNCZF) electrode material is explored for advanced aqueous supercabatteries (ASCBs), with KNCZF and activated carbon–FeBiCu@reduced graphene oxides (AC–FeBiCu@rGO) as cathode and anode, respectively, which outperform aqueous supercapacitors (ASCs) and batteries (ABs) with AC and FeBiCu@rGO anodes because of the synergistic effect of pseudocapacitive (KNCZF), capacitive (AC), and faradaic (FeBiCu@rGO) responses. One of the important findings is that the KNCZF shows a typical bulk phase conversion mechanism for charge storage in the alkaline media with the transition of ABF 3 perovskite nanocrystals into amorphous metal oxides/(oxy)hydroxides nanosheets, showing the redox‐active and redox‐inert roles for the Ni/Co and Zn species, respectively, which can be deduced by various ex‐situ techniques. Another interesting finding is that the redox‐inert Zn species largely enhance the activity of Ni/Co redox‐active species in the ABF 3 materials, mainly owing to the promotion of surface electroactive sites, adsorption of OH − , and charge transfer of surface Ni/Co atoms by Zn‐doping, which can be proved by ex‐situ characterizations and theoretical calculations. Overall, this study reveals the structure–activity relationship and charge storage mechanisms of Zn‐doping ABF 3 materials for advanced ASCBs, showing a great impact on developing advanced electrochemical energy storage.