Modification Of Conducting Polymer With Amorphous Ni-Mo-P Coating And Its Application In Flexible Supercapacitors

The flexible supercapacitors(SCs)are the state-of-the-art portable energy storage devices,which have higher power density and longer cycling life than lithium ion battery as well as higher energy density than parallel-plate capacitor.In recent years,the research hotspots of flexible SCs include not only the development of electrode materials with excellent properties,but also the assembly and performance optimization of device.An essential component in SCs is the flexible electrode,which should possess excellent supercapacitive performance and high mechanical strength.Currently,as for the designs and constructions of the binder-free and flexible electrodes,many research works focus on the active materials directly growing on some flexible conductive carbon-based substrates.In this thesis,based on carbon cloth with high conductivity as the flexible electrode substrate,a series of organic-inorganic hybrids materials were designed and prepared via a simple in-situ polymerization followed by the electrodeposition in order to effectively construct controllable double electric layer and pseudocapacitance materials on the fiber surface inside carbon cloth.The specific research contents are as follows:(1)Polyaniline(PANI)@CFC composites were designed and synthesized via an in-situ polymerization of aniline on the carbon-cloth substrate.The influence of the synthetic conditions such as the molar ratio of oxidant(NH4)2S2O8 to organic monomer,concentration of organic monomer,reaction temperature and time on the performance of the resulted product was investigated.The electrochemical performance of as-prepared material was tested in 1 mol L-1 H2SO4 electrolyte by using a three-electrode system.And a specific capacitance of 486.25 mF·cm-2 at a current density of 1 mA·cm-2 is achieved.(2)The flexible Ni-Mo-P@PANI@CFC sandwiched hybrid materials were successfully designed and synthesized by a two-step process involving the in-situ polymerization of aniline on the CFC substrate followed by the electrodeposition of Ni-Mo-P parthenocissus-like dendrite layer.The influence of the synthetic conditions such as different deposition process,concentration of(NH4)6Mo7O24·4H2O on the performance of the resulted product was investigated.The performance tests show that the fabricated Ni-Mo-P@PANI@CFC sandwiched hybrid keeps 94.6%of specific capacitance retention from 1 to 40 mA·cm-2,and 92.3%of specific capacitance retention at a high current density of 40 mA·cm-2 after 2000 chanrging/discharging cycles.Furthermore,in order to verify the universality of the Ni-Mo-P coating on common CPs,Ni-Mo-P@PPy@CFC and Ni-Mo-P@PEDOT@CFC were also prepared as the controls under identical conditions.Likewise,the supercapacitive performances of PPy and PEDOT can be significantly enhanced in comparison with their Ni-Mo-P uncoated counterparts.(3)In order to further enhance the specific capacity of Ni-Mo-P@PANI@CFC electrode materials,we further designed(Ni-Mo-P@PANI)n@CFC electrode materials via repeatedly alternate coating PANI and Ni-Mo-P alloy layer by layer on the CFC.The influence of the layer numbers on the performance of the resulted product was investigated.The specific capacitances were found to rise almost linearly with increasing the numbers of coating layer.Simultaneously,the capacitance retentions maintain high levels even at 40 mA·cm-2 after 2000 galvanostatic charging/discharging cycles.The all-solid-state symmetric SC was assembled by two pieces of(Ni-Mo-P@PANI)4@CFC electrodes with a cellulose film as the separator and poly(vinyl alcohol)PVA/H2SO4 as the gel electrolyte.The electrochemical measurements indicated that the fabricated flexible supercapacitors exhibited a higher energy density of 0.38 mWh·cm-2 at a power density of 0.4 mW·cm-2.These encouraging results show their great potential in flexible and all solid-state energy storage systems.