Study On Boosting Capacitance Performance Of Polypyrrole@Cellulose Fibers Supercapacitor Electrode By Metal Oxohydroxide

In our previous research works,using the in-situ deposited cobalt oxohydroxide(CoOOH)and the ZIF-67(a cobalt-based metal-organic framework,Co-MOF)derived CoOOH(ZIF-67-OOH)as an interlayer,the capacitance properties of polypyrrole@cellulose fibers(PPy@CFs)paper supercapacitor electrodes were significantly boosted,and the specific capacitance PPy@CoOOH@CFs and PPy@ZIF-67-OOH@CFs were 571.3 and 696.65 F g-1 at a current density of 0.2 Ag-1,respectively.However,the high cost and low abundance of cobalt metal limits its application.Therefore,the search for cheap metal oxohydroxide as an alternative to CoOOH is critically important to develop novel low-cost paper supercapacitor electrodes with high specific capacitance and cycle stability.In this work,cheap nickel oxyhydroxide(NiOOH)and cheaper iron oxyhydroxide(FeOOH)were proposed to replace precious CoOOH as an interlayer to prepare the PPy@MOOH@CFs(M=Ni/Fe)composites,and their capacitance properties were investigated.Firstly.NiOOH was successfully deposited on the surface of CFs based on "liquid phase reduction" in open system at room temperature,and the PPy@NiOOH@CFs composite was obtained by in-situ polymerization process.The results exhibited that the composite electrode had an excellent capacitance performance,and the introduction of NiOOH as an interlayer could improve the specific capacitance(528.4 F g-1 at a current density of 0.2 A g-1)and cyclic stability(capacitance retention of 87.23%after 1000 cycles)for the composite electrode.The results from PPy@NiOOH@CFs composite were very close to those from PPy@CoOOH@CFs composite(specific capacitance of 571.3 F g-1 at a current density of 0.2 A g-1 and capacitance retention of 93.02%after 1000 cycles).suggesting this low-cost and green method has great potential application in flexible supercapacitor.Secondly,the PPy@FeOOH@CFs composite electrode material was successfully fabricated via "liquid phase reduction of NaBH4" in open system at room temperature and in-situ polymerization under ice-bath.The incorporation of FeOOH as an interlayer meliorated the intrinsic defects of PPy@CFs composites.The prepared PPy@FeOOH@CFs paper supercapacitor electrode(PIC-11)obtained a high specific capacitance(513.85 F g-1 at a current density of 0.2 A g-1)and a high cyclic stability(a capacitance retention of 89.36%after 1000 cycles),which could be comparable to PPy@NiOOH@CFs composite.Owing to the excellent capacitance performance and cheaper cost,the PPy@FeOOH@CFs composite paper could be utilized as flexible electrode material in the field of energy storage.The novel low-cost composite paper-based electrode materials(PPy@MOOH@CFs,M=Ni/Fe)developed in this research provide great possibility for the commercial application of flexible supercapacitor electrode materials.