Fabrication Of Aqueous Electrochemical Energy Storage Device And High-Performance Electrodes

It remains highly challenging and opportunity to develop new-type energy storage devices driven by energy crisis and environmental pollution.In the past few decades,lithium ion batteries?LIBs?mainly dominate the markets of rechargeable secondary batteries.Nevertheless,it is urgently desired for exploring low-cost,safe,and eco-friendly energy storage system on account of the limited lithium resources,processing cost,complicated issues of safety,and some environmental issues caused by the electrolyte leakage.As alternatives for LIBs,rechargeable aqueous batteries have captured incremental attention due to cost effectiveness and environmental friendliness.The booming of aqueous Zn ion batteries?ZIBs?is driven by the instinct merits of safety,low cost,abundance in earth crust,environmental benignity and utilizing divalent cations to increase charge-storage capabilities.However,there are still many issues existing in aqueous ZIBs,for example,cumbersome preparation method,inferior performances of overall device,and low cyclic stability of electrode materials,which severely restrict their practical applications.In order to address these issues,we demonstrate three aspects in this thesis based on the safe and low-cost aqueous electrolyte,the functionalization of energy storage device and preparation methods of related electrode materials.?1?An integrated aqueous Zn-ion battery has been fabricated via electrodeposition of the cathode?PANI?and anode?metal Zn?on a laboratory filter paper coated with well-dispersed graphite sheets.The modified filter paper can act as the mechanical support and separator due to interactions posed by cellulose nanofibers,to ensure high flexibility of the integrated aqueous Zn-ion battery.High energy and power densities are also achieved by this integrated aqueous Zn-ion battery.Impressively,the device can tolerate bending,folding and twisting,with little loss in the performance under deformed states.?2?At present,it is complicated to prepare electrode materials for metal sulfide based asymmetric supercapacitors and electrochemical performances of the assembled devices are insufficient.In order to tackle aforementioned issues,we fabricated integrated Ni₃S₂based positive electrode and all-in-one negative electrode by in-situ sulfuration and electro-activation methods,respectively.More importantly,due to the integrated architecture of electrodes without any redundant components,the assembled device exhibits good rate performance and cyclic stability.It opens a new pathway for the practical applications of asymmetric supercapacitors.?3?Abundant and low-cost high-gluten wheat flour was adopted to prepare porous carbon materials for supercapacitors through an innovative method combining high-temperature carbonization with post-electrochemical activation treatment.Different from the carbonization of pure starch,the protein macromolecules consist in the high-gluten wheat flour can improve the graphitization degree and the mechanical strength of the sample during the carbonization process,so that the carbonized sample can maintain initial shape and be used for following electrochemical activation.The prepared material has a specific capacitance of 361F/g at a current density of 1A/g,indicating excellent electrochemical performances.