Capacitive Properties Of Transition Metal Sulfide/graphene Composites

Transition metal sulfide as an electrode material for supercapacitors has been extensively studied,but its poor conductivity has limited its energy storage characteristics.In order to improve its conductivity,this article combines metal sulfide with graphene and explores grapheme amount affects the performance of composite materials.In addition,in order to improve the pseudocapacitance performance of electrode materials,a bimetallic sulfide/hydroxide composite material was successfully prepared,and the influence of the ratio of two metal atoms and the ratio of sulfide to hydroxide on the electrochemical performance was investigated.The main research contents are:（1）3D micro-flower-like Co S and Co S/r GO nanocomposite nanomaterials were synthesized by one-step hydrothermal method.Since the Co S monomer itself is prone to agglomerate and affect its capacitance value,under the three-electrode system,when the current density is 1 A g^-1,it has a mass specific capacitance of 482 F g^-1.Then,the Co S/r GO composite nanomaterial was successfully synthesized by adding graphene.Under the optimal addition amount,the Co S monomer can be uniformly grown on the surface of the graphene.Graphene as a substrate can alleviate the agglomeration of Co S microspheres and make Co S uniformly dispersed.While improving the conductivity of the material and speeding up the transmission rate of electrons.Under the three-electrode system,it has a high specific capacitance of 755 F g^-1 when the current density is 1 A g^-1.After being assembled into a device,after 5000cycles at a current density of 5 A g^-1,it still maintains 89.74%of the initial specific capacitance and has an energy density of 50.84 Wh kg^-1 at a power density of 399.62W kg^-1.（2）The CoNi₂S₄/Co_xNi_1-x（OH）₂ heterostructure electrode material was synthesized by a two-step hydrothermal method.By exploring the ratio of different nickel and cobalt elements and the ratio of CoNi₂S₄ to Ni Co-OH,high redox activity can be achieved,there is a synergistic effect between CoNi₂S₄ and Ni Co-OH with stable electrochemical performance.Under the three-electrode system,when the current density is 1 A g^-1,it has a mass specific capacitance of 1568 F g^-1.（3）In order to improve the conductivity and electrochemical stability of the CoNi₂S₄/Co_xNi_1-x（OH）₂/r GO heterostructure,it is combined with graphene to prepare electrode materials.Under the three-electrode system,it has a high specific capacitance of 1904 F g^-1 at the current density is 1 A g^-1.After being assembled into a device,after 5000 cycles at a current density of 5 A g^-1,it still maintains 92.86%of the initial capacitance,and the energy density is 71.82 Wh kg^-1 when the power density is 399.62 W kg^-1.