Controllable Preparation And Sodium/Potassium Storage Properties Of Metal Sulfide And Its Hybrid Materials

In recent years,lithium-ion batteries with low cost and low pollution have attracted extensive attention because of their high theoretical specific capacity and high working voltage.However,the limited resources of lithium and cobalt and the rapid growth of market demand have led to the price of lithium carbonate,lithium cobalt acid and other materials rising several times.At this time,sodium and potassium elements in the same main group are rich in resources and low prices.Therefore,sodium-ion batteries and potassium-ion batteries have become the key research objectives of various research institutions.Transition metal sulfides have a high specific capacity when used in sodium/potassium ion batteries.However,due to the large radius of sodium and potassium ions,serious volume expansion occurs in the process of the battery cycle,and the cycle life is greatly reduced.Therefore,CoS₂@NC,Co_1-x@ReS₂,and FeS/Co₃S₄/NiS@NC sulfides were prepared by sulfide method,and their sodium/potassium storage properties were studied.(1)The Co-NTA precursors were prepared by hydrothermal method,and the CoS₂@NC composite materials with carbon layer protection nanowires were synthesized by dopamine-coated and sulfide method.When the CoS₂@NC composite materials were used in sodium-ion battery,after 600 cycles at a current density of 1.0 A/g,the CoS₂@NC electrode still has a specific capacity of 315.77 m Ah/g.When used in potassium-ion batteries,it still has a specific capacity of 112.37 m Ah/g after 1000 cycles.The excellent cycling performance of the CoS₂@NC electrode can be attributed to the unique hollow nanowire structure and the protection of the carbon layer.(2)Select the precursor Co-NTA prepared by part of(1),and CoS_1-x was obtained by sulfide,and then nanosheet coated nanowire CoS_1-x@ReS₂ heterostructure was obtained by hydrothermal sulfide.After 570 cycles at a current density of 1.0 A/g,the sodium storage capacity of the CoS_1-x@ReS₂ electrode is 89%,and it still has a specific capacity of 333.49m Ah/g.When applied to a potassium ion battery,the CoS_1-x@ReS₂electrode still has a specific capacity of 173.66 m Ah/g after 250 cycles at a current density of 1.0 A/g.The excellent sodium/potassium storage performance of the CoS_1-x@ReS₂ electrode can be attributed to the unique structure of the hollow nanowires,the protection of rhenium disulfide nanosheets,and the synergistic effect of bimetallic metals.(3)FeCoNi precursors were prepared by co-precipitation method,and then the FeS/Co₃S₄/NiS@NC nanosheets composites with carbon layer protection were synthesized by dopamine-coated and sulfide method.When FeS/Co₃S₄/NiS@NC composites were used in sodium-ion batteries,the electrode still has a specific capacity of 473.25 m Ah/g after 300 cycles at a current density of 1.0 A/g.The excellent cycling performance of the FeS/Co₃S₄/NiS@NC electrode can be attributed to the unique structure of the particle nanosheet,the protection of the carbon layer,and the synergy between three metal sulfides.