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Reducing the activation barrier and stabilizing the sulfur species of Li2S cathodes can ultimately enhance cell efficiency and the cycle life of S‐based Li‐ion batteries (LIBs). Here, a unique synchronous synthesis method is established that can simultaneously construct Li2S encapsulated in conductive protective layers, and accordingly propose a coordination effect of catalysis and domain restriction for Li2S cathodes. Typically, based on the lithiothermic reaction of 8Li + MoS2+ CS2= 4Li2S + Mo + C, the obtained composite features abundant Mo nanocrystals embedded in crystalline Li2S matrices and then wrapped by few‐layer graphene. Notably, all three components derived from lithiothermic reaction are linked by the chemical bonding of MoS and CS, forming a compact Mo‐Li2S‐graphene triple heterostructure. Systematic studies reveal an unprecedented relevancy between charge overpotential and catalytic activation of Mo‐Li2S‐graphene, whereas a low activation potential of 2.43 V is achieved. Further studies disclose the relationship between cycle stability and confinement effect of core‐shell structure, whereas the improved confinement efficiency for polysulfides enables an excellent cycle life for the Li‐S battery. Moreover, the Mo‐Li2S‐graphene cathode demonstrates promising application for LIB, where the Mo‐Li2S‐graphene//SiC battery shows a high capacity of 764 mAh g−1 and outstanding cycle stability. [ABSTRACT FROM AUTHOR]

Reducing the initial activation barrier of Li 2 S is crucial for enhancing the coulomb efficiency and cycle life of Li─S batteries. Herein two Li 2 S-graphene cathode architectures are constructed and investigated the electrocatalytic and domain effects of two graphene on Li 2 S. Systematic studies reveal an unprecedented relevancy between Li 2 S activation and graphene electrocatalysis, as well as an intrinsic relationship between Li 2 S stability and the graphene domain. A dramatically reduced initial activation potential of 2.8 V is achieved via the S─C bonding electrocatalysis of Li 2 S-graphene structure, much lower than the initial activation potential of 3.68   V triggered by two-phase electrocatalysis of Li 2 S/graphene composite. Density functional theory calculations offer mechanism insights into the electrocatalytic effect of S─C bonding on reduced overpotential, and in situ NMR provides solid evidence for the confinement effect of core-shell structure on enhanced cyclability. Notably, a specially designed Li 2 S@graphene cathode with core-shell structure and S─C interactions exhibit both superior electrocatalytic activation and electrochemical reversibility, enabling Li─S battery promising electrochemical properties, including low charge-discharge overpotential, high specific capacity, and excellent cycling performance. More importantly, it demonstrates excellent chemical compatibility within various electrolytes. This study provides valuable theoretical insights for the development of high-performance Li 2 S-graphene cathode materials., (© 2024 Wiley‐VCH GmbH.)

Cr 2 (NCN) 3 is a potentially high-capacity and fast-charge Li-ion anode owing to its abundant and broad tunnels. However, high intrinsic chemical instability severely restricts its capacity output and electrochemical reversibility. Herein we report an effective crystalline engineering method for optimizing its phase and crystallinity. Systematic studies reveal the relevancy between electrochemical performance and crystalline structure; an optimal Cr 2 (NCN) 3 with high phase purity and uniform crystallinity exhibits a high reversible capacity of 590 mAh g -1 and a stable cycling performance of 478 mAh g -1 after 500 cycles. In-operando heating XRD reveals its high thermodynamical stability over 600 °C, and in-operando electrochemical XRD proves its electrochemical Li storage mechanism, consisting of the primary Li-ion intercalation and subsequent conversion reactions. This study introduces a facile and low-cost method for fabricating high-purity Cr 2 (NCN) 3 , and it also confirms that the Li storage of Cr 2 (NCN) 3 can be further improved by tuning its phase and crystallinity.