Preparation And Properties Of Nano-sized Molybdenum Disulfide Supercapacitors

Because of their unique two-dimensional structure and excellent physical and chemical properties,graphene-like two-dimensional layered materials show more promising applications in information processing,electrocatalysis,energy storage and biomedicine.MoS₂ is able to store more charge on or near the active material surface due to pseudocapacitance effect,which leads to higher capacitance.However,the MoS₂ material,as a typical graphene-like material,still has significant limitations due to its low intrinsic electronic conductivity,the generation of sulfides during cycling that lead to stacking,and the material’s susceptibility to bulk agglomeration and shrinkage.In this paper,MoS₂ was successfully compounded with Co-LDH,Mn Mo O₄ and Co Ni-LDH to improve the electrochemical properties of MoS₂ by hydrothermal and co-precipitation synthesis methods.The morphological structure and corresponding electrical properties have been evaluated by various characterisation techniques and electrochemical tests.The main studies are as follows.（1）Successful synthesis of MoS₂/Co-LDH by a simple two-step synthesis method,based on the growth of Co-LDH nanosphere-like composites on MoS₂ nanosheets.The MoS₂/Co-LDH composites were successfully synthesized by adjusting the nature of the solution,etching the Co-MOF nuclei to release Co²⁺ions,and inducing the slow hydrolysis of the ions on Co-MOF to control their nucleation and thus grow ultrathin LDH.The specific capacity of MoS₂/Co-LDH is 280.4 F g^-1 at a current density of 1 A g^-1 and the current density increases from 0.5 A g^-1 to 10 A g^-1 with a capacity retention of 66.7%.The energy density at a power density w of 750 W kg^-1 is 24.40 W kg^-1.The MoS₂/Co-LDH composite electrode material exhibited an ultra-high specific surface area,which successfully demonstrated the synergistic effect of MoS₂ nanosheets and Co-LDH.（2）Electrode materials based on MnMoO₄ nanoparticles grown on MoS₂ nanosheets were prepared,and by embedding small Mn Mo O₄ metal nanoparticles well into the folds of MoS₂ nanosheets,the voids between nanoparticles are expected to improve the electrochemical active sites of electrolytic ions and promote the rapid transfer of electrochemically reactive ions.The defect of MoS₂ can be effectively improved and its electrochemical performance can be improved.Under current density 1 A g^-1,MoS₂/Mn Mo O₄ composite electrode material could reach 596.8 F g^-1,which improved performance by 3.5 times over that of the non-composite MoS₂ electrode.At 750 W kg^-1 the energy density reaches 108.08 W kg^-1 after successfully assembly in ASC devices.（3）A simple synthetic strategy was designed and fabricated to fabricate a MoS₂/Co Ni-LDH core/shell nanosheet on nickel foam,and its electrochemical performance was characterized and evaluated.MoS₂ achieves excellent electrochemical performance due to direct contact with the conducting collector and no binder incorporation,and its well-defined three-dimensional structure has higher specific capacitance performance.The specific capacitance of MoS₂/Co Ni-LDH derived from the GCD curve at a current density of 1 A g^-1 is 3818 F g^-1,and the specific capacitance of MoS₂/Co Ni-LDH is higher than that of MoS₂/NF by 1916 F g^-1,which indicates that the synthesized MoS₂/Co Ni-LDH core/shell composites have great potential for practical applications potential.