Controlled Synthesis And Sodium(Lithium) Storage Performance Research Of(Co,Fe,Sn)based Hollow Nano/micro Functional Materials

The sodium(lithium)batteries have recently attracted increasing attention for large-scale energy storage in renewable energy and smart grid applications.Co,Sn,Fe-based functional materials were used as one of most promising electrodes for SIBs(LIBs)because of the high theoretical capacity,a variety of valence and phase structure,which can be synthesized different morphology and composition of nano-materials through simple chemical method.However,those electrodes suffer drastic capacity deterioration,severe mechanical disintegration due to the tremendous volumetric changes during charge and discharge cycle,resulting in poor stability.The research employed template-assistant and solvothermal reaction to prepare a class of hollow nano/microstructure materials.This kind of material has a high storage capacity and unique hollow porous structure,which is beneficial to improve the cycle stability and the magnification performance.The intrinsic hollow structure can shorten sodium(lithium)transport path,enlarge the specific surface area of electrode and expose more active site,leading to fully chemical reaction between electrode and electrolyte.Meanwhile,the intrinsic hollow structure can alleviate the mechanical stress caused by volume expansion and prolong life-span.Hollow porous MnCO3@SnS2 nanocubes derived from MnCO3 template are fabricated through hydrothermal reaction method.The MnCO3@SnS2 samples were eroded with hydrochloric acid solution,and the change of the morphology of the materials was studied with the erosion time as the control variables.The study found that hollow structure of the SnS2 material was formed completely after 8 hours.The initial charge capacity of the material is 610 mAh g-1 and the stable capacity is 315 mAh g-1 after 200 cycles.Hollow SnS2 anode material shows good cycle stability.The intrinsic hollow structure can effectively buffer the huge volume expansion during electrochemical reaction,and shorten the sodium ion transport path,what's more,the layered structure of SnS2 provides more active sites,which are beneficial to high efficiency.Hollow Fe2O3@MIL-101(Fe)/C nanospheres materials were synthesized by hydrothermal method combined with template-assisted and metal-based framework.It possesses both transition metal oxide material and metal-organic framework material properties,therefore,there is a high specific capacity and stable material skeleton.During the electrochemical cycle,the stable reversible capacity of Fe2O3@MIL-101(Fe)/C electrode is 710 mAhg'1(200 mA g-1 current density),and can be retained at 662 mAhg-1 after 200 cycles with the retention of 93.2%,showing good electrochemical performance.MnCO3 nanocubes materials were prepared by microemulsion method.The MnCO3@CoS nanomaterials were prepared by self-deposition on MnCO3 template surface accompany with hydrothermal reaction.Hollow CoS nanocubes material was formed by the use of hydrochloric acid erosion to remove the MnCO3 template,Electrochemical tests showed that the stable reversible capacity of CoS anode material was maintained at 1050 mAh g-1 at 100 mA g-1 current density,and there was still 990 mAh g-1 capacity after cycling 100 times with a capacity retention rate of 94.3%.Hollow porous CoS samples with well morphology,good dispersion,with a stable cubic configuration and excellent electrochemical performance.