Study On The Interlayer Configuration Of Lithium-Sulfur Battery

With the rapid development of the global economy and social sciences,the increasing environmental pollution,and the exhaustion of energy,environmentally friendly new energy is sought.Lithium-sulfur batteries have become one of the most promising high-energy batteries owing to its high energy density,abundant resources,low cost and environmental friendliness.Nevertheless,there are problems such as poor conductivity of sulfur and sulfide,large volume change,low working voltage,severe shuttle effect,and easy lithium growth of lithium anodes during process of lithium-sulfur batteries,Causes poor cycle performance low Coulombic efficiency,which seriously hinders the commercial production process of lithium-sulfur batteries.In view of the above problems,this paper mainly starts from the interlayer structure,which designs different interlayer structures for lithium-sulfur batteries to improve the electrochemical performances.Three-dimensional porous carbon nanotube flexible paper(MWCNTsP)prepared by multi-walled carbon nanotubes(MWCNTs)and paper fibers by vacuum filtration.Baseing on 3D porous MWCNTsP,doped with dithiothreitol strong(DTT)and modified with the hydroxyl functional group as a novel interlayer structure between the positive electrode and the separator,improving the electrochemical performance.In addition,porous flexible MWCNTsP was used as the current collector and DTT/MWCNTs film was used as the interlayer between the positive electrode and the separator.The unique 3D configuration electrode is more favorable for suppressing the shuttle effect and preparing a high-capacity lithium-sulfur battery.(1)DTT doped with flexible MWCNTsP interlayer can effectively shear the high-order polysulfide to prevent its dissolution,hinder the shuttle effect,improve the cycle performance and the coulombic efficiency of the Li-S battery.The Li-S battery with DTT interlayer structure showed that the initial discharge capacity reached to1288 mAh/g at 0.05 C;the discharge capacity remained 452 mAh/g and Coulomb efficiency of 93% after 200 cycles at 1 C.(2)Modified with the hydroxyl functional group the flexible MWCNTsP interlayer which the-OH can effectively adsorb polysulfide and inhibit the dissolution and diffusion of polysulfide.In addition,the microporous structure of the interlayer structure is also beneficial to the adsorption of polysulfides,and can be used as a secondary current collector to make full use of active substances,improve the cycle performance and the coulombic efficiency of the Li-S battery.The Li-S battery with MWCNTs-OH interlayer showed that the initial discharge capacity reached to 1532 mAh/g at 0.1 C,and 190 cycles at different current rates,showed excellent rate performance.(3)DTT doped with MWCNTs film interlayer can effectively prevent high-order lithium polysulfide from migrating to the anode and shearing high-order polysulfide,inhibiting the production of high-order polysulfides and reducing activity material,improve the cycle performance and the coulombic efficiency of the Li-S battery.The3 D showed that the initial discharge capacity reached to 1352 mAh/g and the Coulombic efficiency reached around 100% with the 3D configuration electrode.Additionally,the batteries maintained a specific capacity of 582 mAh/g and 208mAh/g at the current rate of 5 C and 10 C respectively.