No abstract

As concerns about the safety of lithium‐ions batteries (LIBs) increases, aqueous zinc‐ion batteries (ZIBs) with a lower cost, higher safety, and higher co‐efficiency have attracted more and more interest. However, finding suitable cathode materials is still an urgent problem in ZIBs. In recent years, a lot of significant works have been reported, including manganese‐based cathodes, vanadium‐based cathodes, Prussian blue analog‐based materials, and sustainable quinone cathodes. In this review, some typical cathode materials are introduced. The detailed storage mechanisms and methods for improving the reaction kinetics of the zinc ions are summarized. Finally, the issues, challenges, and the research directions are provided.

are not satisfactory because of the low conductivity of sulfur and extremely dissolving of lithium polysulfide (LPS) in ether-based electrolyte. [8] Adopting the structural carbon materials with abundant pores (e.g., carbon spheres, [9][10][11][12] carbon nanotubes, [13][14][15] graphene [16,17] ) and some metal-based compounds (such as cobalt, [6,18,19] nickel, [21][22][23][24] manganese, [25][26][27][28] iron [29][30][31][32][33][34][35][36][37] ) embedded in carbon host can remarkably improve the electrochemical performance of Li-S batteries. Recently, the researchers have demonstrated that configuring the interlayer between the separator and sulfur cathode is an effective way to alleviate the "shuttle effect" in Li-S redox system. [38][39][40][41][42] To avoid the heavy and large volume of the free-standing interlayer, people have begun to modify the separator with functional materials, such as structural carbon materials [43][44][45][46][47][48] and metal-based compounds. [49,50] As the typical earthabundant, low-cost, and environmentally friendly materials, iron-based compounds have already been widely researched in Li-S batteries. [51][52][53][54] For a long time, the researchers mainly ascribed the enhanced performance of Li-S batteries to strong absorbability of sulfur host materials to LPS (Li 2 S x , x = 1, 2, 4, 6, 8). However, according to the previous researches, [7,20] the binding energy of polar metal-based compounds toward LPS may not the decisive factor; relatively speaking, the catalyst effect of host materials toward LPS plays a leading role in improving the performance of Li-S batteries. Therefore, to better help researchers screen out modified materials suitable for sulfur cathode, it is particularly important to find a "descriptor" that can measure the catalytic ability of sulfur modified materials.Considering these factors, a series of iron-based particles (Fe 3 C@Fe 3 O 4 , Fe 3 O 4 , FeS, and Fe 3 N) embedded in the 3D graphitic carbon material were synthesized as the modified materials for battery separator via a facile two-step method. Among these Fe-based functional materials, the yolk-shell Fe 3 C@Fe 3 O 4 exhibits the best catalytical ability toward LPS in Li-S batteries. By analyzing electronic energy and structure, it has been discovered how the p and d band's center affects the electrochemical performance of Li-S batteries. Not only that, through the ab initio molecular dynamics (AIMD) simulations, it is also observed the dynamic changes of LPS clusters (Li 2 S 6 ) Lithium-sulfur batteries have ultra-high energy density and are considered to be one of the most promising energy storage systems among all battery systems. However, due to various thorny problems, their commercial production has not yet been realized. The current experimental research normally lacks a systematic investigation into the conversion mechanism of the sulfur cathode from the electronic structure level. Actually, there is still a lack of powerful theoretical guidance for the design of high-performance Li-S b...

A hybrid anode based on SnS nanosheets bonded with reduced graphene oxide (SnS NS/RGO) and synthesized with graphene oxide is formed through a facile solvothermal method.