Preparation Of Bacterial Cellulose-based Electrode Materials And Application In Supercapacitors

Supercapacitors are a new type of electrical energy storage devices with high power density and long cycle life,but the energy density is lower than that of secondary batteries.Bacterial cellulose?BC?is a low-cost biomacromolecular material with a three-dimensional porous network structure and excellent mechanical flexibility,thus it is considered as a potential electrode substrate material.Based on this,we have designed and developed two BC-based electrode materials with high energy density,the specific research contents are as follows:?1?We have prepared nickel-manganese layer double hydroxide/polyrrole/bacterial cellulose?NiMn-LDH/PPy/BC?ternary composites by a simple layer-by-layer deposition method.NiMn-LDH/PPy/BC-2 achieves the best electrochemical performance when the concentration of PPy/BC is 0.2 mg mL^-1.The specific capacity is as high as 653.1 C g^-1 at the current density of 1 A g^-1.It was further assembled into an asymmetric supercapacitor with Fe₃O₄@C/MWCNTs.The energy density can reach to 29.8 Wh kg^-1 at a power density of 299.0W kg^-1.?2?We have prepared MOF-PPy/PDA/BC self-supporting flexible electrodes by continuous immersion using metal-organic framework?ZIF-67?as the sacrificial template and polydopamine as the interface modification layer.MOF-PPy/PDA/BC achieves an area specific capacitance of 1.712 F cm^-2 at the current density of 0.4 mA cm^-2.When the current density is up to 20 mA cm^-2,the specific capacitance retention reaches 59.8%.The specific capacitance retention of MOF-PPy/PDA/BC is 71.1%after 5000 charge/discharge cycles at the current density of 2 mA cm^-2.The assembled symmetrical supercapacitor achieves a high specific capacitace of 1.123 F cm^-2 with PVA-H₂SO₄ gel as the solid electrolyte.The volumetric energy density is up to 3.6 mWh cm^-3 at the power density of 12.2 mW cm^-3.