| With the increasing demand for energy and the traditional energy model due to environmental and reserve problems can not meet the new requirements,lithium-ion batteries,supercapacitors and electrocatalytic energy storage technology came into being.In recent years,transition metal compounds,especially transition metal sulfides and hydroxides,have attracted considerable research interest as lithium-ion battery、supercapacitors or electrocatalyst materials.Although the transition metal sulfides and hydroxides as the active materials in the energy conversion and storage and other fields have made great progress,but the materials’ electrochemical performance still needs to be further improved.In this paper,bimetallic sulfide and layered bimetallic hydroxide hollow prism nanomaterials were prepared by sacrificial template method,and their electrochemical performances mentioned above were studied,respectively.The main work is as follows:First,the synthesis of cobalt-manganese bimetallic sulfide hollow nanoprisms/graphene composites and the performance of their lithium-ion batteries.The use of cobalt acetate and manganese acetate in the hydrolysis of ethanolic graphene solution,with polyvinyl pyrrolidone as the morphology control agent,using solvothermal method,the successful synthesis of graphene coated,well-dispersed,with uniform size of the cobalt-manganese acetate hydroxide nanoprisms/graphene composite material((Co,Mn)5(OH)2(CH3COO)8·2H2O/RGO).Using the synthesized cobalt-manganese acetate hydroxide nanoprisms/graphene composite as template and metal source,with thioacetamide as sulfur source,through the hydrothermal reaction to prepare a complete copy of the template of the original morphology of the CoS2@MnS hollow nanoprisms/RGO composite.In the formation of hollow structure,the dissolution of the template and the release of sulfur ion from the hydrolysis of thioacetamide are the key to the successful preparation of hollow nanoprisms.And the material is used for lithium ion battery anode material exhibits a higher specific capacity than conventional commercial graphite electrodes at a current density of 100 mA g-1,200 mA g-1 or even 1000 mA g-1,excellent cycle performance and rate performance.And the reason why the material shows such excellent LIBs performance is mainly due to the following three aspects:the hollow structure of the material greatly shortens the diffusion distance of Li+;the higher specific surface area can ensure that the electrode material is in better contact with the electrolyte solution;2D RGO increases its conductivity and structural strength.Second,the synthesis and electrochemical properties of cobalt-based layered double metal hydroxides(LDHs)hollow nanoprisms.By using the hydrolysis of cobalt acetate in ethanol solution and PVP as the morphology control agent,the cobalt acetate hydroxide(Co5(OH)2(CH3COO)8·2H2O)nanoprisms with good dispersion and uniform size were successfully synthesized by solvothermal method.Ni-Co LDH and Co-Co LDH hollow prism materials were successfully synthesized by adding different transition metal nitrates and using the synthesized cobalt acetate hydroxide nanoprisms as template and cobalt source.The two kinds of hollow LDHs synthesized in this paper successfully replicate the prismatic morphology of the template,and the wall composed of nanosheets,makes the hollow structure stronger.The key of maintaining good integrity of the hollow structure is to adjust the equilibrium relationship between the dissolution of the cobalt acetate hydroxide template,the deposition of the LDH material,and the oxidation of the divalent cobalt ion.We use this material for supercapacitors and electrocatalytic oxygen evolution to explore its use as an electrochemical energy source.The experimental results show that LDHs hollow nanoprisms not only have excellent supercapacitor performance,but also show good electrocatalytic activity in electrocatalytic oxygen evolution. |
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