Phendione-Transition Metal Complexes with Bipolar Redox for Lithium Batteries

1,10-Phenanthroline-5,6-dione (Phendione) - based transition metal complexes are known for their use in pharmacological and catalysis applications. However, their application in electrochemical energy storage has not been investigated thus far. Herein we prove the feasibility of employing phendione - transition metal complexes for electrochemical charge storage by taking advantage of the reversible redox of both, carbonyl groups and transition metal center, contributing thus to augmented charge storage. Interestingly, the chemistry of the counter ion in the studied complexes effectively tunes the solubility and improves the cycling stability. Whereas further studies are required to limit the solubility and active species shuttle, this study explores the bottlenecks of phendione - transition metal complexes as electrode materials for solid electrode format batteries.