Discovery of a “Bipolar Charging” Mechanism in the Solid-State Electrochemical Process of a Flexible Metal–Organic Framework

Metal–organic frameworks (MOFs) are well-known for their application to various types of energy storage; nevertheless, their potential in electron storage has scarcely been investigated. Indeed, the synthetic strategy of MOFs toward the pseudocapactive materials is still absent due to the lack of a detailed insight into the solid-state redox process of MOFs. In this manuscript, we reported the discovery of a new electrochemical mechanism, namely, “bipolar charging” mechanism by analyzing the solid-state electrochemical process of a flexible redox active MOF. In a single redox cycle, not only the Li-ions but also the bulky anions are separately intercalated into the pores of the MOF and contribute to the total capacity. With this “bipolar charging” mechanism, a general synthetic strategy could be proposed. Furthermore, MOF materials employing this mechanism may exhibit remarkable reactivity and high cyclic stability and be adopted as versatile electrode materials in various battery architectures.