A cooperative interface constructed by "lithiophilic" nitrogen-doped graphene frameworks and "sulfiphilic" nickel-iron layered double hydroxides (LDH@NG) is proposed to synergistically afford bifunctional Li and S binding to polysulfides, suppression of polysulfide shuttles, and electrocatalytic activity toward formation of lithium sulfides for high-performance lithium-sulfur batteries. LDH@NG enables high rate capability, long lifespan, and efficient stabilization of both sulfur and lithium electrodes.
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.
Surface reactions constitute the foundation of various energy conversion/storage technologies,s uch as the lithium-sulfur (Li-S) batteries.T oe xpedite surface reactions for high-rate battery applications demands in-depth understanding of reaction kinetics and rational catalyst design. Now an in situ extrinsic-metal etching strategy is used to activate an inert monometal nitride of hexagonal Ni 3 Nt hrough ironincorporated cubic Ni 3 FeN. In situ etched Ni 3 FeNr egulates polysulfide-involving surface reactions at high rates.E lectron microscopywas used to unveil the mechanism of in situ catalyst transformation. The Li-S batteries modified with Ni 3 FeN exhibited superb rate capability,r emarkable cycling stability at ah igh sulfur loading of 4.8 mg cm À2 ,a nd lean-electrolyte operability.T his work opens up the exploration of multimetallic alloys and compounds as kinetic regulators for highrate Li-S batteries and also elucidates catalytic surface reactions and the role of defect chemistry.
Lithium-sulfur (LiS) 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 LiS 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 LiS 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 (LiO and SrS 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 LiS cell yields high rate performance and ultralow capacity decay rate of 0.062% (a quarter of pristine LiS 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 hold great promise to serve as next‐generation energy storage devices. However, the practical performances of Li–S batteries are severely limited by the sulfur cathode regarding its low conductivity, huge volume change, and the polysulfide shuttle effect. The first two issues have been well addressed by introducing mesoporous carbon hosts to the sulfur cathode. Unfortunately, the nonpolar nature of carbon materials renders poor affinity to polar polysulfides, leaving the shuttling issue unaddressed. In this contribution, atomic cobalt is implanted within the skeleton of mesoporous carbon via a supramolecular self‐templating strategy, which simultaneously improves the interaction with polysulfides and maintains the mesoporous structure. Moreover, the atomic cobalt dopants serve as active sites to improve the kinetics of the sulfur redox reactions. With the atomic‐cobalt‐decorated mesoporous carbon host, a high capacity of 1130 mAh gS−1 at 0.5 C and a high stability with a retention of 74.1% after 300 cycles are realized. Implanting atomic metal in mesoporous carbon demonstrates a feasible strategy to endow nanomaterials with targeted functions for Li–S batteries and broad applications.
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