π-Extended Benzo[b]phenazine-Based Polymer Cathode Materials for High-Voltage and Stable Organic Batteries

Abstract

Organic materials are considered potential electrode materials for lithium-ion batteries (LIBs) due to their high theoretical capacity, abundant source, low cost, structure diversity, and environmental friendliness. Herein, we further enhance the discharge voltage and stability by extending the conjugated structure while constructing an active unit based on 5,12-dihydrobenzo[b]phenazine (BPZ) and the corresponding polymer p-DPBPZ. p-DPBPZ|Li cells exhibit excellent integral performances with discharge voltages of up to 3.20–3.45 and 3.85–4.25 V (vs Li+/Li), an initial discharge specific capacity of 151 mAh g–1, and energy density and power density of up to 537 Wh kg–1 and 1965 W kg–1, respectively. Meanwhile, the extended conjugated structure can stabilize the redox intermediates by longer delocalization; thus, the battery shows good cycle stability (average decay rate of 0.0087% per cycle at 2C). Moreover, p-DPBPZ has also shown potential as an active material for sodium-ion batteries. Our study provides innovative structures and an effective strategy for constructing high-performance organic electrode materials.