Study On The Preparation Of Two-dimensional Electrode Materials Of Supercapacitors And Their Electrochemical Performance

One of the key challenges for supercapacitors is their limited energy density.To face this challenge,the focus on the research and development of supercapacitors should be paid to the microstructure control of electrode materials.Based on the electrochemical mechanism of supercapacitors,we prepared various 2D nanostructured electrode materials with high electrochemical performance by adopting different methods.The main result is listed as follows:?1?Study on the preparation of hierarchically structured graphene and its electrochemical performance:Graphene oxide was prepared by a modified Hummer method,and then reduced by a hydrothermal method to obtain the hierarchically nanostructured graphene.The results of electrochemical measurements indicate that the product exhibits intensively faradaic capacitive property.Its specific capacitance is far higher than the theoretical specific capacitance of graphene.It has high specific capacitance of 2152 F g^-1 at low current density of 1.5 A g^-1 and keeps relatively high specific capacitance of 606 F g^-1 at high current density of 60.6 A g^-1..?2?Study on the preparation of nanoflower-like?-MnO₂ and its electrochemical performance:Nanoflower-like?-MnO₂ was prepared by a microwave-assisted hydrothermal method.The flower architecture could provide channels for the fast transfer of electrolyte ions.The thin thickness of nanosheets minimizes the diffusion distance of electrolyte ions beneath the surface of material particles,thus resulting in the high performance of material.It has specific capacitance of 328 F g^-1 at 5 mV s^-1 in 1 M Na₂SO₄ aqueous solution.The capacitance of material still remains 89%of its initial value after 5000 cycles.?3?Study on the preparation of?-Ni?OH?₂ nanosheets and its electrochemical performance:In first step,nickel complex template was prepared by a precipitation method.In second step,two-dimensional?-Ni?OH?₂ nanosheets with high electrochemical performance were prepared by the in-situ reaction of nickel complex template in alkaline electrolyte solution.The nanosheets present high specific capacitance of 2568 F g^-1 at high current density of 1.9 A g^-1,and keep high capacitance of 1066 F g^-1 at high current density of 19.2 A g^-1.?4?Study on the preparation of Ni-Co layered double hydroxide and its electrochemical performance:The two dimensional nickel complex was doped by Co²⁺ions respectively under atmospheric and solvothermal conditions.Then,the double hydroxides with high electrochemical performance was produced by the in-situ reaction of nickel complex in alkaline electrolyte solution.The as-prepared material has high specific capacitance of 2100 F g^-1 at low current density of 2 A g^-1 and keeps high specific capacitance of 1258 F g^-1 at high current density of 41.7 A g^-1.