Fungus Bran-Derived Porous N-Doped Carbon-Zinc Manganese Oxide Nanocomposite Positive Electrodes toward High-Performance Asymmetric Supercapacitors

The common forest waste fungus bran (FB) having the advantages of sustainability, abundance, and availability was used to produce carbon products or carbon matrix hosting composites. The existing abundant nitrogen in FB served as a dopant to in situ dope the formed carbon skeleton. The FB-derived N-doped carbon product was porous (named FPC) and displayed flake structures. Its specific surface area was up to 1515 m(2) g(-1) and had a suitable pore size distribution. This FPC electrode showed a promising capacity of 380 F g(-1) at a current density of 1 A g(-1). The composite was fabricated using FPC as a template to in situ form the zinc manganese oxide (ZMO) nanocubes at different ratios (the composites are denoted FPZM), and the corresponding as-prepared composites (with an FPC-to-ZMO ratio of 1:3) electrode displayed a higher charge capacitance of 537 F g(-1) at 1 A g(-1) and favorable cycle performance. The energy density of an asymmetric device with composite electrode as the positive electrode and FPC as the negative electrode was 13.54 Wh kg(-1) at 700.34 W kg(-1). The synergistic effect between the biomass-derived carbon and pseudocapacitive oxides gave an improved energy-storage performance. Our experimental results show that the forest waste can be effectively utilized as an activated carbon material for wide applications.