Hollow spheres of Mo2C@C as synergistically confining sulfur host for superior Li-S battery cathode

摘要

Lithium-sulfur batteries (LSBs) have attracted much attention in the field of electrochemical energy storage due to their high energy density and low cost. However, the 'shuttle effect' of sulfur cathode, resulting in the poor cyclic performance of batteries, is a big barrier for the development of LSBs. To overcome this critical drawback, herein, a matrix of well-designed double carbon shells-encapsulated metallic Mo2C nanoparticles (Mo2C/C@C) is facilely achieved as an efficient sulfur host for high-performance LSBs. During the electrochemical process, the embedded polar and metallic Mo2C nanoparticles could effectively retard polysulfide migration. While for the carbon layers, they can not only act as conductive matrix but also promote the restriction for all sulfur species and maintain the structural stability simultaneously. Specially, the inner carbon layer is mainly for encapsulation and the outside one for surface-modification. As a result, such well-designed Mo2C/C@CeS cathode could effectively adsorb soluble polysulfides both from chemical and physical aspects, and well confines them inside the porous structure of Mo2C/C@C, thus achieving a high reversible capacity and superior cycling performance.

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