The Radical-redox Mediator In The Cathode Material For High Energy Density Lithium Batteries

Energy storage devices has become more and more attention,owning to important transformative technology to realize low-carbon economy and sustainable energy supply.Lithium-sulfur?Li-S?batteries,due to their low cost and high energy density,represent the potential next-generation energy storage device for a multitude of emerging applications,ranging from stationary grid storage to mobile electric vehicles.However,practical applications are still limited by rapid capacity decay caused by multielectron redox reactions and complex phase transformations.Therefore,the noval radical-redox mediator are introduced into the cathode material of lithium sulfur battery to accelerate the reaction kinetics of polysulfide conversion,suppress the"shuttle effect"and enhance the battery performance.The main contents of the article are as follows:?1?Here,we include commercially available titanium silicalite-1?TS-1?designed a Li-S battery cathode?CNTs-S/TS-1?.Results were obtained that,TS-1 can promote polysulfide conversion,benefiting from functionalities of the strong chemical interactions between the lithium polysulfides?Li PS?and TS-1 in a working Li-S battery.In-situ UV-visible spectroscopy together with other experimental results confirm that incorporation of TS-1 mediators enables direct conversion between S₈^2-and S₃^*-radicals during the discharge process,which effectively promotes the kinetic behaviors of soluble Li PS and regulates uniform nucleation and growth of solid sulfide precipitates.These features give our TS-1 engineered sulfur cathode an ultrahigh initial capacity of 1459m Ah g^-1at 0.1 C.Moreover,the system has an impressively high areal capacity(3.84 m Ah cm^-2)and long cycling stability with a high sulfur loading of 4.9 mg cm^-2.?2?The CNTs,ferrocene?Fc?and glutathione?GSH?were ultrasonically dispersed to obtained composite?CNTs/Fc+GSH?.The cathode?CNTs-S/Fc+GSH?was prepared by conventional coating method.Results were obtained that,the CNTs-S/Fc+GSH cathode achieved a higher initial discharge capacity of 1413 m Ah g^-1 at 0.2 C.At the same time,the electrode retained a discharge capacity of 780 m A h g^-1at 5 C,showing excellent discharge capacity at high rate.Moreover,the electrode still has a reversible capacity of nearly 300 m A h g^-1 after 1500cycles at 2 C with an average capacity decay rate as low as 0.039%per cycle.