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Nanocrystalline Co2P2O7 and carbon nanofiber (Co2P2O7/CNFs) composites with enhanced electrochemical performance were obtained by calcination after a hydrothermal process with NH4CoPO4∙H2O/bacterial cellulose precursors under an argon atmosphere. SEM images showed that the CNFs were highly dispersed on the surfaces of Co2P2O7 microplates. The diagonal size of the Co2P2O7 plates ranged from 5 to 25 µm with thicknesses on a nanometer scale. Notably, with the optimal calcining temperature, the Co2P2O7/CNFs@600 material has higher specific micropore and mesopore surface areas than other samples, and a maximal specific capacitance of 209.9 F g−1, at a current density of 0.5 A g−1. Interestingly, CNF composite electrodes can enhance electrochemical properties, and contribute to better electrical conductivity and electron transfer. EIS measurements showed that the charge–transfer resistance (Rct) of the CNF composite electrodes decreased with increasing calcination temperature. Furthermore, the Co2P2O7/CNF electrodes exhibited higher energy and power densities than Co2P2O7 electrodes.

Summary A flexible electrode of NH4CoPO4 · H2O composite bacterial cellulose (Co‐BC) has been successfully prepared via a hydrothermal method. A bacterial cellulose (BC) membrane was used as a host matrix for nanocrystalline (NC) NH4CoPO4 · H2O. The preparation process included anchoring nanocrystalline NH4CoPO4 · H2O on BC nanofibers with an intrinsic 3D network structure. X‐ray diffraction (XRD) results indicated the orthorhombic structure of the NH4CoPO4 · H2O NC within the Pmn21 space group and BC of a Type‐I structure. FE‐SEM images revealed microplate‐like NH4CoPO4 · H2O structures on BC nanofibers. The a three‐electrode system of all samples were studied for their electrochemical properties by CV, charge/discharge and EIS estimations in a 3 M KOH electrolyte. A maximal specific area capacitance of 158.5 mF cm−2 (43.3 F g−1) was obtained at a current density of 0.25 mA cm−2 using a Co‐BC90 electrode. Moreover, this sample show an excellent capacitance retention of 99% after a 3000 cycle at 1 mA cm−2 current density.