Sulfur Cathode Design Based on Bio-Catalytic Metal-Organic Framework and Its Catalytic Performance in Lithium-Sulfur Batteries
Lithium-sulfur batteries(LSBs)are promising candidates for next-generation energy storage systems due to their high theoretical specific capacity(1 675 mAh∙g-1)and energy density(2 600 Wh∙kg-1).However,the solubility of long-chain lithium polysulfides(LiPSs)in the electrolyte during charging/discharging cycles lead to the shuttle effect,resulting in active material loss from the cathode and capacity degradation.Designing efficient and catalytically active materials to limit LiPSs diffusion and accelerate redox reaction kinetics is crucial to addressing these challenges.Small-molecule bio-catalysts exhibit excellent redox properties,making them ideal candidates.However,their high solubility in conventional LSBs electrolytes causes catalytic material loss during cycling.Metal-organic frameworks(MOFs),featuring metal clusters and organic linkers,offer advantages such as high specific surface area,tunable pore structures,and structural versatility.By leveraging molecular engineering,small organic molecule catalysts immobilized and precisely regulated within the nanoscale confines of MOFs.Therefore,a biomimetic catalytic MOF catalyst(UiO-TECP)was developed using a nano-confinement strategy to immobilize the bio-catalytic unit TCEP within MOF pores,serving as an efficient sulfur host.The MOF's ordered pore structure inhibits LiPS shuttle,while confined TECP accelerates disulfide bond cleavage,enabling rapid LiPSs conversion.The S/UiO-TECP cathode demonstrated a high initial discharge capacity of 841.6 mAh∙g-1 at 1 C and outstanding long cycle stability over 500 cycles,with a capacity decay rate of just 0.06%per cycle.The biomimetic design highlights a promising approach to overcoming LiPSs shuttle effects and offers a pathway for developing advanced catalytic hosts for high-performance LSBs.
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