A phenazine-based organic polymer for long-life sodium storage

Abstract

The lack of efficient and stable anode materials restricts the development of sodium ion batteries (SIBs). Organic materials have excellent sodium ion transmission performance and rich structural adjustability, showing broader application prospects. However, their high solubility and poor conductivity cause unsatisfactory electrochemical performance. In this study, a phenazine-based polymer poly(benzoquinone-alt-diaminophenazine) (PBDP) is developed by polymerizing benzoquinone (BQ) and 2,3-diaminophenazine (DAP) through a mild reaction. The introduced π-conjugated amino groups and extended aromatic plane not only suppress the dissolution of small molecules, but also improve the structural integrity and conductivity of the whole molecule. The obtained PBDP polymer demonstrates a battery capacity of 385 mAh g⁻¹ at 0.05 mA g⁻¹. Notably, it achieves a capacity retention of 87% over 5000 cycles at 1.0 A g⁻¹. Moreover, it retains a capacity of 169 mAh g⁻¹ after 10000 cycles at an ultrahigh current density of 2.0 A g⁻¹. The energy storage mechanism involves redox reactions occurring at the imine sites. This work paves the way for designing high-performance organic electrode materials.