Molecular Design Strategy for High‐Redox‐Potential and Poorly Soluble n‐Type Phenazine Derivatives as Cathode Materials for Lithium Batteries

Abstract The n‐type phenazine (PZ) derivatives represent an emerging class of cathode materials in lithium batteries for low‐cost and sustainable energy storage. However, their low redox potential (<2 V) and high solubility hinder their application to battery systems. To explore and solve such problems in lithium batteries, we investigate the redox characteristics of 13 n‐type PZ derivatives and their dissolution behavior in seven organic electrolytes systematically by using DFT calculations. Two decisive factors are observed to tune the redox potentials for these molecules: the first is the electron density around the N active sites and the second is the chelation on lithium by both the active N and the substituent group. Specific approaches that include the reduction of aromatic rings and the introduction of functional groups at β sites in n‐type PZ derivatives can improve the redox potential to approximately 3 V. In addition, we develop a new index denoted as E diff to investigate the solubility of n‐type PZ derivatives. The most effective way to reduce the dissolution of electrodes in solvents is to improve intermolecular attraction between the electrode molecules by introducing π–π stacking and hydrogen bonds. Such all‐around guidelines should promote the application of n‐type PZ‐based organic cathodes with a high redox potential and low electrode solubility for lithium batteries.