| In recent years,more and more electronic products have been used in people's lives.Of the devices currently used,batteries are the most widely used energy storage devices.However,with the lithium-ion battery most widely used at present as an example,there are still many shortcomings can not be ignored,such as the use of organic electrolytes with low safety and harsh production conditions.In various studies aiming at these drawbacks,waterbased zinc batteries have been widely recognized for their safety and ease of preparation.Therefore,in this dissertation,aqueous zinc-ion batteries are used as research objects to explore the possibility of preparing positive electrode materials from materials such as cellulose and graphite,which are widely sourced and environmentally friendly,and then we systematically study the prepared electrodes.The specific research content of this paper includes the following three parts:1)CNF/GNP composite aerogels were prepared by physical blending of cellulose nanofibers(CNF)and graphene nanoplatelets(GNP),and polypyrrole(PPy)was chemically grown in aerogel pores as an active material to prepare an aqueous system.Zinc ion battery cathode.Compared to traditional electrode materials,cellulose aerogel not only provides a porous and hydrophilic internal structure,but also has application value in terms of environmental friendliness.The electrode material skeleton formed by CNF has good mechanical strength,and the conductivity of CNF and the doping degree of PPy are enhanced by regulating the content of GNP.As a result,an aqueous zinc ion battery positive electrode material obtained by using aerogel having a CNF/GNP mass ratio of 7/3 as a substrate has a specific capacity of 159.4 mAh/g at a current density of 1 A/g,and it has better rate capacity,it still has 85.0% retention after 500 charge and discharge cycles.2)By reducing the graphene oxide with weakly reducing ascorbic acid during the hydrothermal reaction,it is self-assembled into a graphite aerogel with freestanding ability during the reduction process,and PANI is blended therein as a zinc ion battery.Electrode active material.The graphene aerogel substrate prepared by this method not only retains the conductivity of the conventional graphene coating,but also forms a three-dimensional threedimensional conductive structure,which greatly increases its specific surface area.In this experiment,rGO and CNF were used as the “nano-growth point” of PANI,which was polymerized in situ on the surface to change the morphology and doping degree of PANI.The results showed that the electrochemical performance of PANI prepared by “nano growth point” method was better than that of chemical synthesis of PANI.The sample with CNF as “nano growth point” has higher mechanical strength,and the electrode material with r GO as “nano growth point” has higher capacity and reaches 136.1 mAh/g,thus it has good rate performance and can be applied to Higher output power occasions.Samples with "rGO" as "nano growth point" still have 83.5% retention after 500 charging/discharging cycles.3)Using a graphene/CNF composite aerogel as a substrate,manganese dioxide was grown as an active material by electrochemical deposition to prepare a cathode material for an aqueous zinc ion battery.In this experiment,in order to make the pores inside the graphene aerogel link with each other,a hydrophilic CNF is introduced during the preparation of the graphene aerogel substrate,and a hydrophilic channel is formed between the graphene sheets and facilitates the diffusion of the solution and electrolyte.The results show that the manganese dioxide can be evenly coated on the surface of the graphene sheet.After electrodeposition for 15 min,it has a specific capacity of 88.7 m Ah/g at 1 A/g,and a retention rate of 66.7% after 300 charging/discharging cycles. |
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