Synergistic effect of carbon nanotube and encapsulated carbon layer enabling high-performance SnS_2-based anode for lithium storage

Tin disulfide(SnS_(2)),due to large interlayer spacing and high theoretical capacity,is regarded as a prospective anode material for lithium-ion batteries.Nevertheless,the poor electron conductivity of SnS_(2) and huge volumetric change during the lithiation/delithiation process lead to a rapid capacity decay of the battery,hindering its commercialization.To address these issues,herein,SnS_(2) is in-situ grown on the surface of carbon nanotubes(CNT)and then encapsulated with a layer of porous amorphous carbon(CNT/SnS_(2)@C)by simple solvothermal and further carbonization treatment.The synergistic effect of CNT and porous carbon layer not only enhances the electrical co nductivity of SnS_(2) but also limits the huge volumetric change to avoid the pulverization and detachment of SnS_(2).Density functional theo ry calculations show that CNT/SnS_(2)@C has high Li^(+)adsorption and lithium storage capacity achieving high reaction kinetics.Consequently,cells with the CNT/SnS_(2)@C anode exhibit a high lithium storage capacity of 837mAh/g after 100 cycles at 0.1 A/g and retaining a capacity of 529.8 mAh/g under 1.0 A/g after 1000 cycles.This study provides a fundamental understanding of the electrochemical processes and beneficial guidance to design high-performance SnS_(2)-based anodes for LIBs.

Overview of coals as carbon anode materials for sodium-ion batteries

Energy storage is an important technology in achieving carbon-neutrality goals.Compared with lithium-ion batteries,the raw materials of sodium-ion batteries are abundant,low-cost,and highly safe.Furthermore,their costs are expected to be further reduced as large-scale applications take off,making them viable for energy storage applications.The primary anode material for sodium-ion batteries is hard carbon,which has a high sodium-ion storage capacity but is relatively expensive,limiting its applications in energy storage.In order to widen the applications of sodium-ion batteries in energy storage and other fields,it is particularly important to develop anode materials that have both high performance and low cost.Coals,with abundant reserves and worldwide availability,can serve as low-cost carbon sources for anode materials.Additionally,coals of different grades of metamorphism have different structural characteristics that can be tailored for the structural characteristics of coal-based anode materials for sodium-ion batteries.Recent research on tailoring coals as the anode materials for sodium-ion batteries is summarized and the recent progress made towards mitigating the existing issues is analysed in this review.Specifically,the impacts of different grades of metamorphism on the sodium-ion storage performance of coal-based anode materials prepared using direct carbonization are discussed in detail.Studies on improving the electrochemical performances of coal-based anode materials through pore and microcrystalline structure controls and surface as well as interface modifications are presented.Finally,the advantages and disadvantages of different preparation methods are identified.To make the industrial applications of coal-based anode materials for sodium-ion batteries more viable,the importance of the de-ashing process is introduced.