PEDOT-intercalated MnO2 layers as a high-performance cathode material for aqueous Zn-ion batteries

Manganese oxides are considered as a cathode material with great application potential for zinc ion batteries (ZIBs). However, low electron conductivity and slow ion diffusion rate are major limitations restricting their rate capacity and cycle stability. Herein, we creatively intercalated the conductive poly(3,4-ethylenedioxythiophene) into MnO2 layers (sample named PEDOT-MnO2) via a redox precipitation reaction occurring between KMnO4, MnSO4, and EDOT. We used a simpler and more environmentally friendly material preparation process than related studies. The reaction system was a single aqueous phase without organic solvents, and the reaction was carried out in a stirred solution at 0–4 °C for 6 h. The pre-intercalated PEDOT enlarges the spacing of the MnO2 layers and effectively improves the electrical conductivity of the material. In addition, the "structural pillar" effect of PEDOT acting between the layers stabilizes the crystal structure of MnO2. Thus, the optimized sample (PEDOT-MnO2-2) suggests a superior reversible capacity (344 mAh g−1 at 0.2 A g−1), a high-rate performance (121 mAh g−1 at 2 A g−1), and excellent stability (142 mAh g−1 even after 1500 cycles at 2.0 A g−1).