Study Of Electrochemical Properties Based On Transition Metal Chalcogenide

With the rapid development of society,people’s demand for electricity is growing,but the prevailing source of electricity is still mainly obtained through the burning of non-renewable fossil fuels,which is not renewable and poses serious environmental hazards.As a result,clean energy sources such as wind power,hydroelectric power and photovoltaic power are gradually coming into the limelight,but this also raises concerns about energy storage.Lithium-ion batteries are the most widely used energy storage devices,which are widely used in cell phones,computers,electric vehicles and other fields,and are an integral part of our daily life.Recently,transition metal sulfide compounds have been favored by many researchers due to their high specific capacity and low price,but their commercialization is hindered by their tendency to cause volume expansion during charging and discharging and their low electrical conductivity.Although many efforts have been made to improve the stability of transition metal sulfides,it is still a challenge to develop a low-cost,environmentally friendly,and cycle-stable transition metal sulfide based lithium-ion battery cathode material.In this paper,a series of nanocomposites based on transition metal sulfide compounds were designed and synthesized with the aim of improving the specific capacity and cycling stability,and the materials were applied to the anode of lithium-ion batteries,and good electrochemical performance was obtained.The details are shown as follows:（1）We successfully designed and synthesized MoS₂ nanosheets loaded on carbon spheres with3D hollow structure starting from SiO₂ as a template.Due to the unique 3D hollow structure and the doping of carbon materials,the optimal C/MoS₂-0.3 hollow nanocomposites exhibit excellent electrochemical performance and can still reach an ultra-high reversible capacity of 958.50 m Ah g^-1 after up to more than 900 cycles at a high multiplicative current density of 0.5 A g^-1.（2）We designed and synthesized a series of CoS₂-coated triple N-doped carbon dodecahedral framework composites using a simple two-step heat treatment method and a cobalt-based zeolite imidazolium framework（ZIF-67）as a precursor.Since graphitic N-doped carbon in the composites can promote electron transport on the carbon framework,while pyrrole N-doped carbon can reduce the diffusion potential barrier of lithium ions in the electrode.Therefore,the best CoS₂@NC-400composite exhibits excellent electrochemical performance and can still reach a reversible capacity of 767.6 m Ah g^-1 after 500 cycles at a current density of 0.5 A g^-1.（3）We designed and successfully synthesized Zn-doped MoSe₂/SnSe₂/SnSe nanocomposites attached to a dodecahedral nitrogen-doped carbon framework derived from ZIF-8 using ZIF-8 as a template,and the optimal ZMSSNC-200 nanocomposites exhibited relatively excellent electrochemical properties.When the current density was 0.5 A g^-1,a reversible capacity of 350m Ah g^-1 could still be achieved after 500 cycles.