Studies On The Synthesis Of Self-supporting MoS₂-based Hybrid Electrodes And Their Electrochemical Properties

Supercapacitors and lithium-ion batteries have received extensive attention and research due to their advantages of low cost,high energy density,long cycle life,and environmental friendliness.High capacity electrode materials and reasonable electrode structure are the key to improving the e lectrochemical performance of supercapacitors.MoS₂ has rich ionic valence state,high theoretical specific capacity,and has broad development prospects in the field of energy storage.However,MoS ₂ is easy to agglomerate,easy to stack between layers,poor conductivity.In order to solve these problems,it is an effective method to combine MoS ₂ with materials which have high electrical conductivity.Metal nitrides have received extensive attention due to their ultra-high electrical conductivity,such as VN and MoN.Therefore,combining it with MoS₂ is expected to obtain electrode materials with better electrochemical performance.Therefore,in this paper,these materials are used as the substrate to support MoS₂,and they are committed to preparing composi te materials with higher electrochemical performance.The main research contents and conclusions are as follows:(1)VN/MoS₂ self-supporting electrodes is synthesized by a simple three-step method.Among them,the specific capacitance of VN/MoS ₂-6H at a scan rate of 100m V s^-1 was 523.1 m F cm^-2,that is much higher than that of VN-500(162.2 m F cm^-2)and MoS₂(226.2 m F cm^-2).In addition,the prepared sample was used for the negative electrode of lithium ion battery.The discharge capacity of the first cycl e of VN/MoS₂-6H was 6.8 m Ah cm^-2,and the discharge capacity of the second cycle was still 6.16 m Ah cm^-2.After 500 cycles at the current density of 17.0 m A cm^-2,the capacity retention rate is 95%and the Coulomb efficiency is 100%.(2)Prepare Mo₂C substrate by seed-assisted hydrothermal and calcination method,and then use hydrothermally method grow MoS₂ to obtain Mo₂C/MoS₂self-supporting electrode.The results show that Mo₂C exhibits an irregular block structure,and MoS₂ nanosheets are evenly distributed on these block structures.The problem of easy aggregation and stacking of layered MoS ₂ is effectively improving.The specific capacitance of Mo₂C/MoS₂-2 at a scan rate of 5 m V s^-1 is 2160.6 m F cm^-2,which is much higher than that of Mo₂C(135.6 m F cm^-2).After 2000 cycles at a scan rate of 100 m V s^-1 for Mo₂C/MoS₂-2,the capacity retention rate was 79%.(3)Use the same method to prepare MoN/Mo₂C/MoS₂ self-supporting electrode.The results show that MoN/Mo₂C exhibits a nanowire structure,while MoS₂nanosheets are evenly distributed on the nanowires.The results showed that the specific capacitances of MoN/Mo₂C/MoS₂-3 at a scan rate of 5 m V s^-1 were 2432 m F cm^-2,much higher than MoN/Mo₂C(305 m F cm^-2).After 2000 cycles at a scan rate of100 m V s^-1 for MoN/Mo₂C/MoS₂-3,the capacity retention rate was 93%,and it had good cycle stability.