| In recent years,the booming market of new-energy vehicles and Artificial Intelligence（AI）requires energy storage devices with larger capacity,longer life and higher safety.Supercapacitor（SC）,as an emerging energy storage technology,has a wide range of applications in the field of mobile and wearable electronics due to its advantages of good safety,high power density and long cycle life.However,supercapacitor has fallen behind lithium-ion battery in terms of commercialization because of its narrow voltage window and low energy density.Zn-Ag battery has considerable energy density and stable battery performance,but also has high production cost and poor service life.The design of novel electrode materials is an attractive strategy for optimizing and enhancing the performance of supercapacitors and Zn-Ag batteries.In particular,the innovation of composite electrodes from the nanoscale is of great significance for reducing costs,improving capacity and cycle performance.In this paper,new composite electrodes have been prepared based on Zn O-based and Ag-based materials,and their structures have been optimized by various modification methods to obtain hybrid supercapacitor（HSC）with high energy density and long cycle life.Moreover,functional materials have been introduced to modify the Ag-based electrode material,so as to enable supercapacitor to achieve electrochromic.1.A ternary composite r GO/Zn O/Pp PD with a 3D structure has been prepared via hydrothermal reaction and in-situ polymerization,in which Zn O nanoparticles are loaded on r GO sheets and then coated with polyphenylenediamine（Pp PD）.In a three-electrode system,the specific capacitance of r GO/Zn O/Pp PD is 320 F g-1,which is 551.7%higher than the 58 F g-1 of pure Zn O.In addition,r GO/Zn O/Pp PD displays outstanding stability even after 1000cycles at 5 A g-1 with 81%retention of the initial capacitance.Moreover,symmetrical supercapacitor based on the r GO/Zn O/Pp PD exhibits the maximum power density and energy density is 10 k W kg-1 and 18.14 Wh kg-1,respectively.2.A ternary composite r GO/Ag/Pp PD has been obtained by reducing graphene oxide and silver ions,and polymerizing the Pp PD coating.And the effect of initiator dose on the yields of composite has been also discussed in detail.Besides,Ag nanoparticles and Pp PD are introduced as pseudocapacitance materials into composite,which allows the specific capacitance of r GO/Ag/Pp PD to reach 2779 m F cm-2(926 F g-1)at 1 m A cm-2.Under the synergistic effect of the three components,r GO/Ag/Pp PD as an electrode retains 89.42%of initial capacitance after 2000 cycles at 40 m A cm-2,illustrating excellent cycle stability.When r GO/Ag/Pp PD electrode has been assembled into a symmetric device,the fabricated supercapacitor demonstrates wonderful performance with an energy density of 23 Wh kg-1 at a power density of 0.5 k W kg-1.3.A composite CNFs/GO/ZIF8（CGZ）film has been synthesized from monodisperse ZIF8（Zeolitic Imidazolate Framework）crystals,cellulose nanofibers（CNFs）and graphene oxide（GO）in room temperature and aqueous solution.Subsequently,this CGZ film has been pyrolyzed at high temperature to obtain a Zn O-based highly conductive electrode CCGZ film（Carbonized-CNFs/GO/ZIF8）.The results of structural characterization manifest that CCGZ film has a highly ordered microstructure,which achieves the free-standing and integration of electrode.Furthermore,this thin film without any binder has a conductivity of 270.2 S cm-1,and a specific capacitance of 423.8 F g-1 at 5 m V s-1 which is more than 15 times higher than Zn O/carbon composite derived from ZIF8.When the power density is 200 W kg-1(132 m W cm-3),the all-solid-state symmetric supercapacitor fabricated by CCGZ film can deliver an energy density of 14.92 Wh kg-1(9.84 m Wh cm-3).After 10800 cycles,the tremendous capacitance retention rate of 87.23%indicates the tremendous cycle stability of this device.4.A conductive CNFs-Ag NWs film has been prepared via vacuum filtration,and its conductivity and transmittance can be realized by adjusting the mass density of Ag NWs.Then,transparent CNFs-Ag NWs/WO3 composite film with dual functions of energy storage and electrochromic property has been synthesized by electrochemical deposition.In the voltage range of-1.5 V～0.4 V,this film can change from dark blue to light blue and then fade back to transparent.Meanwhile,the CNFs-Ag NWs/WO3 film has a coloration efficiency of 58.65 cm2 C-1,with a coloring and bleaching time of 2.2 s and 1.1 s,respectively.Additionally,the area-specific capacitance of CNFs-Ag NWs/WO3 film is 111.6 m F cm-2 at 2m A cm-2.Transparent supercapacitors（TSCs）assembled from CNFs-Ag NWs/WO3 films have been confirmed to create a remarkable capacity of 11.5 m F cm-2 at 0.4 m A cm-2,and enabled intuitive monitoring of energy storage levels through color changes.5.A battery-type hybrid supercapacitor（Zn-Ag BSH）has been assembled using r GO/Ag/Pp PD composite and CCGZ film as positive and negative electrodes respectively,which enables energy storage device with high energy density and stable cycle performance.Furthermore,Zn-Ag BSH demonstrates an excellent capacity of 56.67 m Ah g-1 at a current density of 1 A g-1.A voltage window of up to 1.5 V contributes an energy density of 55.01 Wh kg-1 to Zn-Ag BSH,and can light up the red LED sign,showing great practical value.At the same time,Zn-Ag BSH exhibits outstanding cycle stability with a capacity retention rate of up to 94.07%after 500 cycles at 3 A g-1 and 72.16%after 1000 cycles at 77 A g-1. |
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