An in situ constructed VO2–VN binary host was realized to accomplish smooth immobilization–diffusion–conversion of polysulfides, targeting high-sulfur-load Li–S batteries.

Rechargeable lithium–sulfur batteries have attracted tremendous scientific attention owing to their superior energy density. However, the sulfur electrochemistry involves multielectron redox reactions and complicated phase transformations, while the final morphology of solid‐phase Li2S precipitates largely dominate the battery's performance. Herein, a triple‐phase interface among electrolyte/CoSe2/G is proposed to afford strong chemisorption, high electrical conductivity, and superb electrocatalysis of polysulfide redox reactions in a working lithium–sulfur battery. The triple‐phase interface effectively enhances the kinetic behaviors of soluble lithium polysulfides and regulates the uniform nucleation and controllable growth of solid Li2S precipitates at large current density. Therefore, the cell with the CoSe2/G functional separator delivers an ultrahigh rate cycle at 6.0 C with an initial capacity of 916 mAh g−1 and a capacity retention of 459 mAh g−1 after 500 cycles, and a stable operation of high sulfur loading electrode (2.69–4.35 mg cm−2). This work opens up a new insight into the energy chemistry at interfaces to rationally regulate the electrochemical redox reactions, and also inspires the exploration of related energy storage and conversion systems based on multielectron redox reactions.

The lithium–sulfur (Li–S) battery is regarded as a next‐generation energy storage system due to its conspicuous merits in high theoretical capacity (1672 mAh g−1), overwhelming energy density (2600 Wh kg−1), and the cost‐effectiveness of sulfur. However, the practical application of Li–S batteries is still handicapped by a multitude of key challenges, mainly pertaining to fatal lithium polysulfide (LiPS) shuttling and sluggish sulfur redox kinetics. In this respect, rationalizing electrocatalytic processes in Li–S chemistry to synergize the entrapment and conversion of LiPSs is of paramount significance. This review summarizes recent progress and well‐developed strategies of the mediator design toward promoted Li–S chemistry. The current advances, existing challenges, and future directions are accordingly highlighted, aiming at providing in‐depth understanding of the sulfur reaction mechanism and guiding the rational mediator design to realize high‐energy and long‐life Li–S batteries.

Lithium-sulfur (LiS) batteries are strongly considered as the next-generation rechargeable cells. However, both the shuttle of lithium polysulfides (LiPSs) and sluggish kinetics in random deposition of lithium sulfides (Li S) significantly degrade the capacity, rate performance, and cycling life of LiS cells. Herein, bifunctional Ba Sr Co Fe O perovskite nanoparticles (PrNPs) are proposed as a promoter to immobilize LiPSs and guide the deposition of Li S in a LiS cell. The oxygen vacancy in PrNPs increases the metal reactivity to anchor LiPSs, and co-existence of lithiophilic (O) and sulfiphilic (Sr) sites in PrNP favor the dual-bonding (LiO and SrS bonds) to anchor LiPSs. The high catalytic nature of PrNP facilitates the kinetics of LiPS redox reaction. The PrNP with intrinsic LiPS affinity serves as nucleation sites for Li S deposition and guides its uniform propagation. Therefore, the bifunctional LiPS promoter in LiS cell yields high rate performance and ultralow capacity decay rate of 0.062% (a quarter of pristine LiS cells). The proposed strategy to immobilize LiPSs, promotes the conversion of LiPS, and regulates deposition of Li S by an emerging perovskite promoter and is also expected to be applied in other energy conversion and storage devices based on multi-electron redox reactions.

Lithium–sulfur (Li–S) batteries have extremely high theoretical energy density that make them as promising systems toward vast practical applications. Expediting redox kinetics of sulfur species is a decisive task to break the kinetic limitation of insulating lithium sulfide/disulfide precipitation/dissolution. Herein, we proposed a porphyrin‐derived atomic electrocatalyst to exert atomic‐efficient electrocatalytic effects on polysulfide intermediates. Quantifying electrocatalytic efficiency of liquid/solid conversion through a potentiostatic intermittent titration technique measurement presents a kinetic understanding of specific phase evolutions imparted by the atomic electrocatalyst. Benefiting from atomically dispersed “lithiophilic” and “sulfiphilic” sites on conductive substrates, the finely designed atomic electrocatalyst endows Li–S cells with remarkable cycling stablity (cyclic decay rate of 0.10% in 300 cycles), excellent rate capability (1035 mAh g−1 at 2 C), and impressive areal capacity (10.9 mAh cm−2 at a sulfur loading of 11.3 mg cm−2). The present work expands atomic electrocatalysts to the Li–S chemistry, deepens kinetic understanding of sulfur species evolution, and encourages application of emerging electrocatalysis in other multielectron/multiphase reaction energy systems.

Lithium–sulfur (Li–S) batteries hold great promise as a next‐generation battery system because of their extremely high theoretical energy density and low cost. However, ready lithium polysulfide (LiPS) diffusion and sluggish redox kinetics hamper their cyclability and rate capability. Herein, porphyrin‐derived graphene‐based nanosheets (PNG) are proposed for Li–S batteries, which are achieved by pyrolyzing a conformal and thin layer of 2D porphyrin organic framework on graphene to form carbon nanosheets with a spatially engineered nitrogen‐dopant‐enriched skin and a highly conductive skeleton. The atomic skin is decorated with fully exposed lithiophilic sites to afford strong chemisorption to LiPSs and improve electrolyte wettability, while graphene substrate provides speedy electron transport to facilitate redox kinetics of sulfur species. The use of PNG as a lightweight interlayer enables efficient operation of Li–S batteries in terms of superb cycle stability (cyclic decay rate of 0.099% during 300 cycles at 0.5 C), good rate capability (988 mAh g−1 at 2.0 C), and impressive sulfur loading (areal capacity of 8.81 mAh cm−2 at a sulfur loading of 8.9 mg cm−2). The distinct interfacial strategy is expected to apply to other conversion reaction batteries relying on dissolution–precipitation mechanisms and requiring interfacial charge‐ and mass‐transport‐mediation concurrently.

Smart energy storage has revolutionized portable electronics and electrical vehicles. The current smart energy storage devices have penetrated into flexible electronic markets at an unprecedented rate. Flexible batteries are key power sources to enable vast flexible devices, which put forward additional requirements, such as bendable, twistable, stretchable, and ultrathin, to adapt mechanical deformation under the working conditions. This review summarizes the recent advances in construction and configuration of flexible batteries and discusses the general metrics to benchmark various flexible batteries with different materials and chemistries. Moreover, we present advanced prototype flexible batteries developed by some companies to afford general envision of the technological status. Lastly, the critical points are summarized in the development of flexible batteries and remaining challenges are also presented for the future design of flexible batteries in practical perspectives. K E Y W O R D S composite electrode, flexible batteries, smart energy storage, ultrathin batteries, wearable electronics 1 | INTRODUCTION Rechargeable batteries have popularized in smart electrical energy storage in view of energy density, power density, cyclability, and technical maturity. 1-5 A great success has been witnessed in the application of lithium-ion (Li-ion) batteries in electrified transportation and portable electronics, and non-lithium battery chemistries emerge as alternatives in special applications from cost and safety views. 6-10 While energy/power

Magnesium–sulfur batteries promise high volumetric energy density, enhanced safety, and low cost for electrochemical energy storage. The current obstacles to practical applications of reliable magnesium–sulfur batteries are finding electrolytes that can meet a multitude of rigorous requirements along with efficient sulfur cathodes and magnesium anodes. This review highlights recent advances in designing better electrolytes, cathodes, and anodes. A suitable electrolyte for magnesium–sulfur batteries should allow to reversibly electroplate/strip divalent magnesium ions and should be compatible with the sulfur cathode and the other cell's components. Another challenge to be addressed is the careful engineering of the interface and microstructure in the sulfur scaffold to effectively mitigate the soluble magnesium polysulfide shuttle and to enhance the reaction kinetics. We highlight that the ongoing research in this field encourages the fundamental understanding of the reaction mechanisms and the interplay among the different components by diverse characterization techniques.