| With the progress of science and technology and the development of high technology war situation,the soldier’s individual combat ability and survival ability have attracted more and more attention,which requires the soldiers to carry enough equipment and supplies to ensure their continued combat capability.Therefore,smart wearable individual combat equipment that combines lightweight,convenient and energy storage has emerged.With the development of technologies such as sensors,wireless communication networks and microchips,smart clothing is becoming more and more multifunctional,which makes smart wearable energy storage not only applicable to special fields such as aerospace and defense military,but also gradually to the civilian development.The future development goal of smart clothing is to integrate it into clothing without affecting the comfort level of clothing.The flexibility,weavability and deformation performance of energy storage electronic devices become the key factors for the development of smart clothing.At present,the development of two-dimensional flexible supercapacitors in wearable electronic devices is largely limited by their large in size,heavy in weight,small in specific capacity,low in energy density,and poor in breathability.Fiber-shaped supercapacitors(FSSs)have the merits of small volume,high flexibility and easy assembly into various designed structures that attract increasing interest and are considered as one of the promising energy storage candidates for wearable textiles.However,one-dimensional FSSs generally have lower energy densities,lower stretchability,and capacitor performance that deteriorate in extreme environments.Therefore,it is urgent to have a breakthrough study in related fields.In this thesis,we designed a FSS with high energy density based on the conductive polymer.Then,we developed a highly stretchable tandem FSS and solved the problem of low energy density and the deteriorate performance of the supercapacitors at extreme temperatures.An integrated self-powered supercapacitor was further studied.The main contents are summarized as follows:Stretchable fiber-shaped tandem supercapacitor.Wearable electronic devices are inevitable bended and stretched during application.Stretchable fiber-shaped supercapacitors in particular can be realized by winding fiber electrodes on elastomeric substrates or by assembling fiber electrodes into a helical geometry.Additional metal wire interconnections are often required when electrically connecting multiple fiber supercapacitors(in series or in parallel)to satisfy the voltage or current output specifications of the intended applications.However,a series connection of the device in the stretching process tends to breakdown or damage.Therefore,integration of the device is of vital importance in practical application.Here I circumvent these problems by developing a new type of "internal tandem" stretchable fiber-shaped supercapacitors based on high crystalline "all-in-one" polymer fiber with wet-spinning method.This polymer fiber has the combined properties of high conductivity,high flexibility,high specific capacitance and wide electrochemical window that can simultaneously function as electrical conductive wire and as energy storage electrode in an assembled device.The symmetric assembled tandem FSS groups are fabricated without the use of metal wire and additional welding connection showing tunable voltage output,tailored capacitance and outstanding stretchablility.The resulting andem FSS groups assemblies consisting of 8 serially connected cells display high-voltage output of 12.8V,ultrahigh energy density of 41.1 μW h cm-2 at power density of 3520 pW cm-2 and remarkable stretchability of up to 400%without obvious capacitance degradation.This work provides a new family of flexible fiber electrode and novel concept designs of flexible power systems that could be threaded or integrated into wearable and portable electronics.Wide-temperature fiber-shaped supercapacitor.Most of reported FSSs are operated at room temperature and used the toxic flammable organic electrolyte or corrosive strong acid or base which may have safety hazards especially for wearable textiles directly sticking on the human skin at harsh environmental temperatures.The performance of the supercapacitors may deteriorate at extreme temperatures which results in issues such as capacitance decay,internal resistance increase,cycle life degradation and thermal runaway triggered by thermal stress from internal heat generation,which severely limit the practical application.The key method to solve the electrochemical performance deterioration of supercapacitors in extreme environments is to design a new kind of all-climate FSS by combination of aqueous LiCI-PVA based gel polymer electrolyte and core-shell nanocrystalline polymer fiber electrode.The inner core of the fiber consists of conductive polymer and a small amount of amorphous RuO2 which provide high pseudocapacitance.The outer shell consists of nanocrystalline conductive polymer which not only provides pseudocapacitance,but also functions as current collector and buffer layer that suppress the structural pulverization and prevent the possible side-reaction of the RuO2 under extreme operating temperature.The new kind of aqueous symmetric FSSs with high safety and record high areal energy density at wide operating temperature ranging from-60 to 75℃ based on aqueous LiCI-PVA based gel electrolyte.Even at the temperature of-60℃,the FSSs still can deliver high energy density of 14.2 μW h cm-2.The capacitance of FSS still could maintain 97.2%after 5000 cycles at-60℃,respectively.It shows the potential application in wide temperature wearable electronics.Self-powered fiber-shaped supercapacitor.On the basis of solving the application of FSS in flexible stretchable and wide temperature range,the rapid self-discharge of FSS has always been a serious problem.While the development of self-powered energy storage devices can effectively solve the self-discharge problem and make people get rid of the complete dependence on the power network.Although solar energy is clean,renewable and unlimited,solar energy is an intermittent power supply due to the limited availability of the sunlight.Therefore,we designed a multifunctional fiber electrode material can be used as the common-used electrode for the energy harvest and energy storage units.Meanwhile,the structural stability,electrode connecting and integration capability of the self-powered supercapacitor can be further improved.As a result,the elf-powered supercapacitor based on the conductive polymer electrodes demonstrate a highest total energy conversion efficiency(TCE)of 5.1%,ultralong 1700 cycle stability and long term stability of 63 days.To the best of our knowledge,the TCE of 5.1%with 1700 cycle stability is among the best in the reported performance of SCs.This provides a good prospect for self-powered integrated electronics to power wearable electronic devices.In summary,this thesis studies a series of high stretchability,all,climate and self-powered FSS based on conductive polymers fiber electrode.We have deeply researched the influence of inorganic acids on the structure of conductive polymers and the influence of structural rearrangement of conductive polymers on its electrical conductivity,mechanical properties and electrochemical performance,which has positively promoted the understanding of the energy storage process and mechanism of conductive polymers.In addition,the multi-functional flexible FSSs also provide new ideas and methods for the development of wearable energy devices. |
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