Review Article Electrocatalysts in lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries with the merits of high theoretical capacity and high energy density have gained significant attention as the next-generation energy storage devices.Unfortunately,the main pressing issues of sluggish reaction kinetics and severe shuttling of polysulfides hampered their practical application.To overcome these obstacles,various strategies adopting high-efficient electrocatalysts have been explored to enable the rapid polysulfide conversions and thereby suppressing the polysulfide shuttling.This review first summarizes the recent progress on electrocatalysts involved in hosts,interlayers,and protective layers.Then,these electrocatalysts in Li-S batteries are analyzed by listing representative works,from the viewpoints of design concepts,engineering strategies,working principles,and electrochemical performance.Finally,the remaining issues/challenges and future perspectives facing electrocatalysts are given and discussed.This review may provide new guidance for the future construction of electrocatalysts and their further utilizations in high-performance Li-S batteries.

Promoting polysulfide conversions via cobalt single-atom catalyst for fast and durable lithium-sulfur batteries

Although promising strategies have been developed to resolve the critical drawbacks of lithium-sulfur(Li-S)batteries,the intractable issues including undesirable shuttling of polysulfides and sluggish redox reaction kinetics have still been unresolved thoroughly.Herein,a cobalt single-atom(CoSA)catalyst comprising of atomic Co distributed homogeneously within nitrogen(N)-doped porous carbon(Co-NPC)nanosphere is constructed and utilized as a separator coating in Li-S batteries.The Co-NPC exposes abundant active sites participating in sulfur redox reactions,and remarkable catalytic activity boosting the rapid polysulfide conversions.As a result,Li-S batteries with Co-NPC coating layer realize significantly enhanced specific capacity(1295 mAh·g^(-1)at 0.2 C),rate capability(753 mAh·g^(-1)at 3.0 C),and long-life cyclic stability(601 mAh·g^(-1)after 500 cycles at 1.0 C).Increasing the areal sulfur loading to 6.2 mg·cm^(-2),an extremely high areal capacity of 7.92 mAh·cm^(-2)is achieved.Further in situ X-ray diffraction,density functional theory calculations,and secondary ion mass spectrometry confirm the high catalytic capability of CoSA towards reversible polysulfide conversion.This study supplies new insights for adopting single-atom catalyst to upgrade the electrochemical performance of Li-S batteries.