Updated Metal Compounds (MOFs, -S, -OH, -N, -C) Used as Cathode Materials for Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries have the potential to be as efficient and as widespread as lithium-ion (Li-ion) batteries, since sulfur electrode has high theoretical capacity (1672 mA h g(sul)(-1)) and this element is affordable. However, unlike their ubiquitous lithium ion (Li-ion) counterparts, it is difficult to realize the commercialization of Li-S battery. Because the shuttle effect of polysulfide inevitably results in the serious capacity degradation. Tremendous progress is devoted to approach this problem from the aspect of physical confinement and chemisorption of polysulfide. Owing to weak intermolecular interactions, physical confinement strategy, however is not effective when the battery is cycled long-term. Chemisorption of polysulfide that derived from polar-polar interaction, Lewis acid-base interaction, and sulfur-chain catenation, are proven to significantly suppress the shuttle effect of polysulfide. It is also discovered that the metal compounds have strong chemical interactions with polysulfide. Therefore, this review focuses on latest metal-organic frameworks metal sulfides, metal hydroxides, metal nitrides, metal carbides, and discusses how the chemical interactions couple with the unique properties of these metal compounds to tackle the problem of polysulfide shuttle effect.