Catalytic Co9S8 decorated carbon nanoboxes as efficient cathode host for long-life lithium-sulfur batteries

Lithium sulfur(Li-S)batteries with high specific capacity and energy density can bring enormous opportunities for the nextgeneration energy storage systems.However,the severe dissolution and shuttle effect of lithium polysulfides(LiPSs)is still the key issue that seriously impedes the development of practical Li-S batteries.Here,polar Co9S8 inlaid carbon nanoboxes(Co9S8@C NBs)have been investigated as cathode host for high-performance Li-S batteries.In this integrated structure,Co9S8 nanocrystals not only provide strong chemisorptive capability for polar LiPSs,but also act as a catalyst to accelerate polysulfide redox reactions;while carbon nanobox with large inner space can offer enough space to relieve the volume expansion and physically confine LiPSs’dissolution.As a result,the S/Co9S8@C NBs cathode exhibits high specific capacity at 1C and the capacity retention was^83%after 400 cycles,corresponding to an average decay rate of only^0.043%per cycle.

MoSe2 nanosheets as a functional host for lithium-sulfur batteries

Lithium-sulfur batteries(LSBs) hold great potential for large-scale electrochemical energy storage applications. Currently, the shuttle of soluble lithium polysulfide(LiPSs) intermediates with sluggish conversion kinetics and random deposition of Li2S have severely degraded the capacity, rate and cycling performances of LSBs, preventing their practical applications. In this work, ultrathin MoSe2 nanosheets with active edge sites were successfully grown on both internal and external surfaces of hollow carbon spheres with mesoporous walls(MCHS). The resulting MoSe2@MCHS composite acted as a novel functional reservoir for Li PSs with high chemical affinity and effectively mediated their fast redox conversion during charge/discharge as elucidated by experimental observations and first-principles density functional theory(DFT) calculations. The as-fabricated Li-S cells delivered high capacity, superior rate and excellent cyclability. The current work presents new insights on the delicate design and fabrication of novel functional composite electrode materials for rechargeable batteries with emerging applications.

Modularized sulfur storage achieved by 100% space utilization host for high performance lithium-sulfur batteries

Popularization of lithium-sulfur batteries(LSBs) is still hindered by shuttle effect and volume expansion.Herein, a new modularized sulfur storage strategy is proposed to solve above problems and accomplished via employing 100% space utilization host material of cobalt loaded carbon nanoparticles derived from ZIF-67. The modular dispersed storage of sulfur not only greatly increases the proportion of active sulfur,but also inhibits the occurrence of volume expansion. Meanwhile, 100% space utilization host material can greatly improve the conductivity of the cathode, provide a larger electrolyte wetting interface and effectively suppress the shuttle effect. Moreover, loaded cobalt particles have high catalytic activity for electrochemical reaction and can effectively improve the redox kinetics. The cell with new cathode host material carbonized at 650 ℃(ZIF-67(650 ℃)) exhibits superior rate performance and can maintain a high specific capacity of 950 m Ah/g after 100 cycles at 0.2 C, showing a good cycle stability.

Recent advances in cathodes for all-solid-state lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries have been regarded as the candidate for the next-generation energy storage system due to the high theoretical specific capacity(1675 m Ah/g), energy density(2600 Wh/kg)and the abundance of elemental sulfur, but the application of Li-S batteries is impeded by a series of problems. Recently, all-solid-state Li-S batteries(ASSLSBs) have drawn great attention because many drawbacks such as safety issues caused by metallic lithium anodes and organic liquid electrolytes can be overcome through the use of solid-state electrolytes(SEs). However, not only the problems brought by sulfur cathodes still exist, but more trouble arouses from the interfaces between SEs and cathodes, hampering the practical application of ASSLSBs. Therefore, in order to deal with the problems, enormous endeavors have been done on ASSLSB cathodes during the past few decades, including engineering of cathode active materials, cathode host materials, cathode binder materials and cathode structures. In this review, the electrochemical mechanism and existing problems of ASSLSBs are briefly introduced. Subsequently, the strategies for developing cathode materials and designing cathode structures are presented. Then there follows a brief discussion of SE problems and expectations, and finally, the challenges and perspectives of ASSLSBs are summarized.