The development of electrocatalysts with high catalytic activity is conducive to enhancing polysulfides adsorption and reducing activation energy of polysulfides conversion, which can effectively reduce polysulfide shuttling in Li-S batteries. Herein, a novel catalyst NiCo-MoO_x/rGO (rGO = reduced graphene oxides) with ultra-nanometer scale and high dispersity is derived from the Anderson-type polyoxometalate precursors, which are electrostatically assembled on the multilayer rGO. The catalyst material possesses dual active sites, in which Ni-doped MoO_x exhibits strong polysulfide anchoring ability, while Co-doped MoO_x facilitates the polysulfides conversion reaction kinetics, thus breaking the Sabatier effect in the conventional electrocatalytic process. In addition, the prepared NiCo-MoO_x/rGO modified PP separator (NiCo-MoO_x/rGO@PP) can serve as a physical barrier to further inhibit the polysulfide shuttling effect and realize the rapid Li⁺ migration. The results demonstrate that Li-S coin cell with NiCo-MoO_x/rGO@PP separator shows excellent cycling performance with the discharge capacity of 680 mAh·g⁻¹ after 600 cycles at 1 C and the capacity fading of 0.064% per cycle. The rate performance is also impressive with the remained capacity of 640 mAh·g⁻¹ after 200 cycles even at 4 C. When the sulfur loading is 4.0 mg·cm⁻² and electrolyte volume/sulfur mass ratio (E/S) ratio is 6.0 μL·mg⁻¹, a specific capacity of 830 mAh·g⁻¹ is achieved after 200 cycles with a capacity decay of 0.049% per cycle. More importantly, the cell with NiCo-MoO_x/rGO@PP separator exhibits cycling performance under wide operating temperature with the reversible capacities of 518, 715, and 915 mAh·g⁻¹ after 100 cycles at −20, 0, and 60 °C, respectively. This study provides a new design approach of highly efficient catalysts for sulfur conversion reaction in Li-S batteries.

Lithium metal batteries (LMBs) based on metallic Li exhibit high energy density to be competent for advanced energy storage applications. However, the unstable solid electrolyte interphase (SEI) layer due to continuous decomposition of electrolytes, and the attendant problem of Li dendrite growth frustrate their commercialization process. Herein, a hybrid SEI comprising abundant LiF, lithiophilic Li-Ge alloy, and Ge nanoparticles is constructed via a simple brush coating method. This fluorinated interface layer with embedded Ge-containing components isolates the Li anode from the corrosive electrolyte and facilitates homogenous Li nucleation as well as uniform growth. Consequently, the modified Li anode exhibits remarkable stability without notorious Li dendrites, delivering stable cycling lives of more than 1000 h for symmetric Li||Li cells and over 600 cycles for Li||Cu cells at 1 mA·cm⁻². Moreover, the reinforced Li anodes endow multiple full-cell architectures with dramatically improved cyclability under different test conditions. This work provides rational guidance to design an artificial hybrid SEI layer and would stimulate more ideas to solve the dendrite issue and promote the further development of advanced LMBs.

Lithium–sulfur (Li-S) batteries have been considered as promising candidates for large-scale high energy density devices due to the potentially high energy density, low cost, and more pronounced ecological compatibility. However, the complex Li-S conversion reactions, unsatisfactory battery performance, and unsafe metallic Li anode restrict the development of Li-S batteries to achieve commercialization. This review mainly focuses on three aspects which are the remaining challenges, recent advances, and applications in Li-S batteries. Firstly, this review portrays Li-S conversion chemistry involving the multi-step and multi-electron reaction mechanism, as well as the remaining challenges. Then, the scientific strategies and very recent advances of the cathode, electrolyte, lithium anode, and other constituent parts of Li-S batteries are detailly summed up, as well as their advantages and limitations. For the sake of promoting the Li-S batteries practicalization, next section is primarily concerned with problems, the corresponding solutions, and application scenarios of practical pouch cells. Finally, the important findings as guidelines and some future directions as trends for developing emerging Li-S batteries are briefly summarized.