Preparation Of High-performance Electrode Materials From Bacterial Cellulose For Electrochemical Energy Storage

Supercapacitors as a new-type energy storage devices have drawn much attention because they can provide higher power density than batteries and higher energy density than traditional dielectric capacitors, which show great potential application for portable electronics, power back-up, electrical vehicles, and so on. In this paper, the electrode materials including N-doped carbon nanofibers(N-CNFs), heteroatom-doped carbon nanofibers and Ni3S2/carbon nanofibers(Ni3S2/CNFs) were successfully prepared using the simple method derived from bacterial cellulose(BC). The morphologies, structure characteristics and electrochemical performances of these materials were investigated by X-ray diffraction(XRD) patterns, scanning electron microscopy(SEM), transmission electron microscopy(TEM) and high-resolution transmission electron microscope(HRTEM), X-ray photoelectronic spectroscopy(XPS), N2 absorption-desorption and electrochemical measurements.(1) N-CNFs with partial graphitization structure were successfully prepared via in-situ polymerization of pyrrole onto the BC, followed by carbonize at a low pyrolysis temperature. The results show that N-CNFs with conductive network architecture can enable fast electron and ion transport, improve the specific capacitance, rate performance and cycling stability of the material.(2) Heteroatom-doped carbon nanofibers(N-CNFs, N, P-CNFs and N, S-CNFs) were successfully prepared by impregnating NH4NO3, NH4H2PO4 and(NH4)2SO4 into the BC pellicles, followed by carbonization in N2 atmosphere at 800 °C and NH3 atmosphere at 700 °C. The abundant functional groups of BC allow for easy doping with nitrogen, nitrogen/phosphorus, and nitrogen/sulphur. Due to the nitrogen/phosphorus co-doped, N, P-CNFs electrode displayed higher specific capacitance and better stability than N-CNFs and N, S-CNFs electrodes.(3) The Ni3S2 nanoparticles have been successfully grown on CNFs derived from BC via a hydrothermal method, this composite have been employed as the electrode material for supercapacitor and presented high performance. An asymmetric supercapacitor has been constructed Ni3S2/CNFs as the positive electrode and CNFs as the negative electrode, which show higher power density and energy density and superior cycling stability. Moreover, the as-assembles supercapacitor can power a LED 3 min after charging 20 s, which exhibites a great potential application in practical.