Preparation And Energy Storage Study Of The Muti-dimensional Pseudocapacitance Materials

Supercapacitors have attracted substantial attention in recent years due to their high power densities,fast charge/discharge rate and excellent cycle stability.The pseudocapacitors offer much higher specific capacitance by making use of reversible Faradaic reactions that take place at the interface between the electrode and electro-lyte.Therefore,the research focused on supercapacitors is developing pseudocapaci-tor electrode materials with great electrochemical performance.However,a lot of de-fects found in pseudocapacitors including aggregation,low electrical conductivity and poor structure stability limit its application in supercapacitors.To imporving the pre-formance of pseudocapacitors,this dissertation chooses three materials of pseudoca-pacitor blend with different substrates for synthesizing the compound,which have the novel structure,large surface areas and good electrical conductivity and structure sta-bility.The Ni_1/3Co_2/3?OH?₂/CNT composite are facilely and effectively prepared through the etching reaction by using the Cu₂O nanoparticle as templates and CNTs as supporting framwork.The hollow Ni_1/3Co_2/3?OH?₂ nanoparticles uniformly en-wound with CNTs have large surface area,good electric conduction and structure sta-bility,which benefit the improvement of electrochemical performance.When the current density increases to 40 A g^-1,the specific capacitance of Ni_1/3Co_2/3?OH?₂/CNT composite still maintain 78%of the initial value(1896 F g^-1 at 1 A g^-1 current density).After testing over 5000 cycles at 10 A g^-1 current density,the retention of specific ca-pacitance is 84.7%.For futher enhancing the electrochemical performance,the GO was used as the substrate to grow the uniformly dispersed Cu₂O nanoparticles,which depresse the obvious agglomeration of hollow Ni_1/3Co_2/3?OH?₂ nanoparticles.In the meanwhile,the carbon papers are replaced by Ag current collectors for improving the electric conduction of the whole electrode.When the current density increases to 50 A g^-1,the specific capacitance of Ni_1/3Co_2/3?OH?₂/RGO composite still maintain 40%of the initial value(3942 F g^-1 at 5 A g^-1 current density).After testing over 5000 cycles at 10 A g^-1 current density,the retention of specific capacitance is 88.9%.Binder-free Co₃O₄@layered double hydroxide?Co₃O₄@LDH?core-shell hybrid architectural nanowire arrays are prepared by two-step hydrothermal method.LDH nanosheets with large electroactive surface area uniformly disperse on the surface of Co₃O₄ nanowires,which allows fast electron transport and enhances the electrochem-ical performance of LDH nanosheets.Co₃O₄@LDH nanowire arrays with 2 to 1.5molar ratio between Co₃O₄ and LDH exhibit high specific capacitance(1104 F g^-1 at 1A g^-1),good rate capability and cycling stability?87.3%after 5000 cycling?,which is attributed to the synergistic effect of the robust Co₃O₄ nanowire arrays and LDH na-nosheets on electrochemical performance.Themolybdenumdisulfide/reducedgrapheneOxide@polyaniline?MoS₂/RGO@PANI?composite was facilely and effectively prepared through a two-step synthetic method.The rational combination of two components allowed a uniform dispersion of polyaniline?PANI?on the surface of molybdenum disul-fide/reduced graphene oxide?MoS₂/RGO?.The synergistic effect induced by the combined components resulted in outstanding energy storage performance in terms of high specific capacitance(1224 F g^-1 at 1 A g^-1),good rate capability(721 F g^-1 at 20A g^-1)and cycling stability?82.5%retention after 3000 cycles?.The symmetric su-percapacitor made of MoS₂/RGO@PANI displayed interesting characteristics,such as a high specific capacitance of 160 F g^-1 at 1 A g^-1,a maximum energy density of 22.3Wh kg^-1 and power density of 5.08 kW kg^-1.