High performance N-doped carbon nanosheet/MnO2 cathode derived from bacterial cellulose for aqueous Zn-ion batteries

Abstract

Rechargeable aqueous Zn-ion batteries (ZIBs) have obtained extensive attention owing to their high safety, low-cost, environmental friendliness and high energy density. Nevertheless, developing suitable cathode materials remains challenging due to requirements for appropriate microstructure. We present a porous N-doped carbon nanosheet/MnO₂ (NCS/MnO₂) derived from bacterial cellulose (BC) by a simple route. BC chunks were soaked in urea solution and then carbonized under Ar flow at 900 °C. N-doped carbon nanosheets were obtained and MnO₂ was added by reaction with NaMnO₄. Benefiting from both the conductivity and porosity of the NCS support, the NCS/MnO₂ composite delivers a high capacity and long cycling stability (114 mA h g⁻¹ at 2 A g⁻¹ after 1800 cycles). The electrode reaction mechanism was further investigated and the MnO₂ dissolution/deposition mechanism was confirmed, with a critical role of zinc sulfate hydroxide (ZSH) to assist the deposition of MnO₂.