Innovative Strategy to Asymmetric Supercapacitors: Microcrystalline Cellulose as a Dual-Role Substrate for Positive and Negative Electrodes

It is well-known that nickel-based metal–organic frameworks (MOF) and MnO have obvious redox properties. However, poor electrical conductivity of the MOF and water solubility of MnO limit their use in asymmetric supercapacitors (ASC). Using substrate materials is a viable strategy, but the positive and negative capacity gap owing to substrate material differences is still a research challenge. To resolve this issue, our work employs an entirely different strategy. Microcrystalline cellulose (MCC) serves as a foundational material for both positive and negative electrodes. The electrode materials (cello-MOF-L-0.1 and cello-M) obtained via this strategy are integrated into ASC devices, which significantly enhance the poor performance resulting from the disparity between the two electrodes, therefore achieving superior electrochemical performance. The morphological structure and chemical composition of the materials were also investigated using X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) techniques. The constructed ASC device can achieve a charge storage capability of 400 C g–1 (0.2 A g–1) and 43 Wh kg–1 at a power density of 723 W kg–1. At a current density of 10 A g–1, the ASC device loses a capacity of 15% after 5000 cycles. Further, the potential reasons contributing to the varied performances and the mechanisms of charge storage have been thoroughly probed through scientific characterization methods.