Investigating the Electrochemical Behavior of Cobalt(II) Terephthalate (CoC8H4O4) as the Organic Anode in K-ion Battery

•Cobalt terephthalate as the organic anode was studied in K-ion cell•Nearly 100% Coulombic efficiencies could be maintained•The average capacities of 146 mAh g−1 for 200 cycles were realized

The electrochemical behavior of cobalt terephthalate (CoTP) as the organic anode was initially carried out in K-ion battery, with the main intention to test whether the abnormal capacity enhancement of CoTP previously occurring in Li-ion battery could continuously happen in the different K-ion battery system. However, as confirmed by the cyclic voltammetry and X-ray photoelectron spectroscopy (XPS), the Co element of CoTP was irreversibly reduced from Co2+ cation to Co0 atom in the 1st discharge process, thus converting CoTP into K2TP in the following electrochemical cycles. Despite of that, the satisfactory specific and rate capacities could be realized for CoTP after a small amount of conductive Super P was added, with the average capacities of 146 mAh g−1 for 200 cycles under the current density of 60 mA g−1, which were comparable or even superior to some inorganic anodes recently reported for K-ion battery.

Graphical abstractDownload high-res image (180KB)Download full-size image