Copper Porphyrin as a Stable Cathode for High‐Performance Rechargeable Potassium Organic Batteries

Abstract

Rechargeable potassium‐ion batteries (KIBs) are promising alternatives to lithium‐ion batteries for large‐scale electrochemical energy‐storage applications because of the abundance and low cost of potassium. However, the development of KIBs is hampered by the lack of stable and high‐capacity cathode materials. Herein, a functionalized porphyrin complex, [5,15‐bis(ethynyl)‐10,20‐diphenylporphinato]copper(II) (CuDEPP), was proposed as a new cathode for rechargeable potassium batteries. Spectroscopy and molecular simulation studies were used to show that both PF6− and K+ interact with the porphyrin macrocycle to allow a four‐electron transfer. In addition, the electrochemical polymerization of the ethynyl functional groups in CuDEPP resulted in the self‐stabilization of the cathode, which was highly stable during cycling. This unique charge storage mechanism enabled CuDEPP to provide a capacity of 181 mAh g−1 with an average potential of 2.8 V (vs. K+/K). These findings could open a pathway towards the design of new stable organic electrodes for KIBs.

A Self‐Conditioned Metalloporphyrin as a Highly Stable Cathode for Fast Rechargeable Magnesium Batteries

“…On the other hand, the irreversible reductive peaks in the CV could be ascribed to the reduction of Cu 2+ to Cu + . This phenomenon is also observed for CuDEPP in Mg(HMDS) 2 /MgCl 2 /PP 14 TFSI (Figure S13) and in KPF 6 electrolytes [21] . This attribution was confirmed by X‐ray photoelectron spectroscopy (XPS) as the Cu 2p peak in the first discharge state shifts approximately 2 eV to lower binding energies compared to the pristine material (Figure 3c).…”

“…Facile reduction and oxidation of fused‐ring organics is well known, and metal complexes of porphyrin and phthalocyanine with promising redox behavior in monovalent metal‐ion‐based electrochemical energy storage systems of Li [19,20] and K [21] were reported recently. Introducing terminal alkyne functionality and a copper(II) cation as central atom was found to significantly improve the stability of [5,15‐bis‐(ethynyl)‐10,20‐diphenylporphinato]copper(II) (CuDEPP) upon cycling.…”

Toward High‐Performance Dihydrophenazine‐Based Conjugated Microporous Polymer Cathodes for Dual‐Ion Batteries through Donor–Acceptor Structural Design

“…When the battery was charged to 4.4 V, the peaks centered at 134.2 and 685.3 eV correspond to the characteristic signals of P 2p and F 1s from the stored PF 6 − anion. [56,57] After discharging to 1.6 V, the obvious decrease in the intensity of P and F signals demonstrated the deinsertion of PF 6…”

Organic Electrode Materials for Non-aqueous K-Ion Batteries

“…Thereby, the natures of electrode materials are significant for the performance and safety of KIBs. Cathode materials can be generally categorized into Prussian blue and its analogs (PBAs) [17,18], polyanionic compounds [19,20], layered metal oxides [21,22], and organic materials [23][24][25]. Anode materials commonly include carbonaceous [26][27][28], K-alloying [29,30], conversion-type [31,32], and organic materials [33].…”