Conjugated and Non-conjugated Polymers Containing Two-Electron Redox Dihydrophenazines for Lithium-Organic Batteries

Organic p-type cathode materials have recently attracted increasing attention due to their higher redox potentials and rate capabilities in comparison to n-type cathodes. However, most of the p-type cathodes based on one-electron redox still suffer from limited stability and low specific capacity (<150 mAh g(-1)). Herein, two polymers, conjugated poly(diethyldihydrophenazine vinylene) (CPP) and non-conjugated poly(diethyldihydrophenazine ethylidene) (NCPP) containing two-electron redox dihydrophenazine, have been developed as p-type cathode materials. It is experimentally and theoretically found that the conjugated linkage among the redox centers in polymer CPP is more favorable for the effective charge delocalization on the conjugated polymer backbone and the sufficient oxidation in the higher potential region (3.3-4.2 V vs. Li/Li+). Consequently, the CPP cathode displays a higher reversible specific capacity of 184 mAh g(-1) with excellent cycling stability.

Automated summary

Organic p-type cathode materials have gained attention for their higher redox potentials and rate capabilities. However, most of the p-type cathodes based on one-electron redox still have limited stability and low specific capacity. In this study, two polymers, CPP and NCPP, containing two-electron redox dihydrophenazine, were developed as p-type cathode materials. The results show that the conjugated linkage in CPP is more favorable for charge delocalization and oxidation at higher potentials, leading to a higher reversible specific capacity of 184 mAh g(-1) and excellent cycling stability.