Conductive Metal–Organic Framework with Superior Redox Activity as a Stable High-Capacity Anode for High-Temperature K-Ion Batteries

Abstract

High-temperature rechargeable batteries are essential for energy storage in elevated-temperature situations. Due to the resource abundance of potassium, hightemperature K-ion batteries are drawing increasing research interest. However, raising the working temperature would aggravate the chemical and mechanical instability of the KIB anode, resulting in very fast capacity fading, especially when high capacity is pursued. Here, we demonstrated that a porous conductive metal−organic framework (MOF), which is constructed by N-rich aromatic molecules and CuO 4 units via π−d conjugation, could provide multiple accessible redox-active sites and promised robust structure stability for efficient potassium storage at high temperatures. Even working at 60 °C, this MOF anode could deliver high initial capacity (455 mAh g −1 ), impressive rate, and extraordinary cyclability (96.7% capacity retention for 1600 cycles), which is much better than those of reported high-temperature KIB anodes. The mechanistic study revealed that C�N groups and CuO 4 units contributed abundant redox-active sites; the synergistic effect of π−d conjugated character and reticular porous architecture facilitated the K + /e − transport and ensured an insoluble electrode with small volume deformation, thus achieving stable high-capacity potassium storage.

Arresting dissolution of two-dimensional metal–organic frameworks enables long life in electrochemical devices

“…These results indicate that the three-electron reduction of Cu 3 HHTT 2 occurs both on the HHTT moieties and the Cu nodes, consistent with previous reports on Cu-MOFs. 15,31,33…”

“…1–3 Typically, 2D cMOFs host multitopic π-conjugated aromatic ligands in square planar MX 4 (X = O, NH, or S) linkages that repeat and create porous 2D sheets. Various 2D cMOFs have been synthesized using ligands with core structures ranging from benzene 4–12 to larger structures 13–17 like triphenylene, 18–22 coronene, 23 phthalocyanine, 24,25 and hexa-cata-hexabenzocoronene. 26 This structural versatility, coupled with favorable physical properties and the potential for redox activity from both ligands and metal nodes, has prompted the exploration of 2D cMOFs as electrode materials for electrochemical energy storage (EES).…”

A synergistic pinning effect in a layer-structured oxide cathode for enhancing stability towards potassium-ion batteries

“…1–4 Presently, they are in urgent need of cathode materials which can offer high specific capacity and long-term cycling stability to support large-scale applications. 5–7 Potential cathode categories, such as transition metal oxides, 8,9 polyanionic materials, 10–12 Prussian blue analogs, 13,14 and organic compounds, 15–17 have been extensively investigated. 3,6,18,19 Layered transition metal oxides (K x TMO 2 , TM = transition metal) stand out owing to their unique intercalation mechanism, high theoretical capacity and flexible elemental composition advantages.…”