Novel naphthalene benzimidazole-based materials for potassium metal batteries: revealing the importance of molecular weight for material performance

A family of novel naphthalene benzimidazole (NBI)-based materials with different molecular weights was prepared by condensing 1,4,5,8-naphthalenetetracarboxylic dianhydride with 2,3-diaminophenazine, 2,3,7,8-tetraaminophenazine or their mixture. Of these materials, only intermediate molecular weight NBI provides high specific discharge capacity and exhibits good cycling stability and rate capability in potassium cells, while polymeric NBI also demonstrated decent performance in lithium cells. The results suggest a new approach for further rational design of NBI materials for metal-ion batteries with improved performance.