Boosting charge transfer of polymer with reduced graphene oxide for efficient NH4+ storage

Abstract

Organic materials have emerged as promising NH₄⁺ storage materials due to their advantages including rich resources and abundant active sites. However, they face challenges, such as poor conductivity and limited cycling stability. In this study, we synthesize an organic polymer, poly-quinol-phenylenediamine (POLA), and prepare POLA-30 by incorporating POLA into reduced graphene oxide (rGO). The incorporation of rGO with mechanical robustness, excellent conductivity, and large specific surface area significantly enhances the charge transfer and structural stability of POLA-30. In 0.5 M (NH₄)₂SO₄ electrolyte, POLA-30 shows a low median discharge voltage of −0.47 V at 0.05 A g⁻¹, a high specific capacity of 149 mA h g⁻¹ at 0.05 A g⁻¹, and retains 70 % of original capacity after 5000 cycles at 0.5 A g⁻¹. Ex-situ analyses further elucidate the insertion/de-insertion mechanism of NH₄⁺ in POLA-30. Additionally, a full cell assembled with POLA-30 anode and δ-MnO₂ cathode maintains 78 % of its initial capacity after 700 cycles at 0.05 A g⁻¹. This study reflects the broad application prospects of polymer electrodes.