A universal small-molecule organic cathode for high-performance Li/Na/K-ion batteries

Organic solids are mainly composed by organic molecules interacted by Van der Waals forces, which indicates that every organic molecule can independently store electrons and counter metal ions during redox reaction in rechargeable metal-ion batteries. However, the serious dissolution problem as well as the solvent structure in electrolytes limits this universal capability for organic electrodes. In this article, a novel small-molecule organic compound namely 1,1′-(1,4-phenylene)-bis(perylene-3,4,9,10-tetracarboxylic dianhydride) (2PTCDA, 125 mAh g−1) is intentionally designed, in order to increase the insolubility against liquid electrolytes and partially extend its π-π aromatic skeleton without sacrificing the redox activity and specific capacity. Based on the insolubility and the properly-selected electrolytes, 2PTCDA can exhibit almost the same cathode performance in all Li/Na/K-ion half and full cells. Specifically, 2PTCDA can deliver the redox potential range of 1.4–3.6 V (vs. Li/Na/K) and discharge capacities of 120–137 mAh g−1 in Li/Na/K-ion half cells.