Solution-processed perylene diimide-ethylene diamine cathodes for aqueous zinc ion batteries

Organic electroactive compounds can be applied as alternative cathodes in rechargeable zinc ion batteries (ZIBs) instead of using inorganic cathode materials with low stability or high toxicity. However, many reported organic ZIB cathodes have some limitations, which are their tedious synthesis processes and low yields. In this work, perylene diimide-ethylenediamine/carbon black (PDI-EDA/CB) composites are prepared with a high yield of over 88% under mild conditions via a solution-based processing method. As the organic cathodes in aqueous ZIBs, the PDI-EDA/CB composites have a high specific capacity of 118.0 mA h g^-1 at 0.05 A g^-1; this capacity can be maintained as 95.0 mA h g^-1 even at a high current density of 5.00 A g^-1. Also, PDI-EDA/CB has good cycling stability by reserving 70.5% of its initial capacity after 1500 charge-discharge cycles at 1.00 A g^-1, outperforming many recently reported ZIB cathodes. As disclosed by the structural and electrochemical characterization of PDI-EDA/CB, its excellent electrochemical performance is due to the zinc ion storage mechanism of PDI-EDA and the solution-based fabrication method.