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Lithium–sulfur batteries with potentially high specific energy are viewed as very promising candidates for next‐generation lightweight and low‐cost rechargeable batteries. However, sulfur‐based cathodes suffer from dissolution of polysulfides causing shuttle effects. Here, in order to confine elemental sulfur and anchor the polysulfides, a novel host that is an inexpensive natural clay mineral, viz., vermiculite is proposed. When compared to regular carbon–sulfur composites, vermiculite–sulfur composites offer promising rate capability and much better cycling stabilities, displaying capacity retentions of ≈89 and ≈93% within 200 cycles at C/2 and 1 C, respectively, and ≈60 % at C/5 within 1000 cycles. Postmortem studies, advanced adsorption tests, density functional theory calculations, and zeta potential measurements in combination with intrinsic characteristics of the natural vermiculite provide insights into the new mechanism. The vermiculite contains naturally present surface cations which show a strong tendency to adsorb Sn2− anions, hence protecting them from dissolution. The excess surface charge is most probably compensated by excess Li+ in the space charge zones which is beneficial for charge transfer and local conductivity. The reported results show that natural clay‐minerals are promising sulfur hosts being able to fixate sulfides via electrical double layer effects, thus enabling high‐performance in lithium–chalcogen batteries. [ABSTRACT FROM AUTHOR]

Metal fluorides (MFs) are regarded as high‐capacity conversion cathode materials for next‐generation lithium‐ion batteries with high energy density. However, these cathodes suffer from poor electronic conductivity, sluggish reaction kinetics, and deleterious cathode solid electrolyte interface (CEI) formation, which may cause rapid cell degradation upon cycling. Herein, a low temperature chemical vapor deposition (CVD) carbon coating technology is successfully achieved to coat MFs‐FeF2 with a thin amorphous carbon layer, which promotes the formation of a stable CEI with improved electronic and ionic transport property. Consequently, a discharge capacity higher than 450 mAh g−1 of the CVD coated FeF2 is achieved with a capacity retention at about 75% after 2500 cycles in a saturated electrolyte. Moreover, an unprecedented cycling performance with the discharge capacity of 350 mAh g−1 after 500 cycles in a super diluted electrolyte is also achieved. Advanced cryo‐electron microscopy reveals that the carbon coating significantly suppresses the undesirable CEI formation and promotes the formation of a thin CEI with excellent chemo‐mechanical property. This work provides a feasible technology to stabilize the important interface on MFs and offers a new strategy to accelerate the commercial adoption of such cathodes. [ABSTRACT FROM AUTHOR]

Abstract: Cupric oxide (CuO) represents an attractive anode material for sodium‐ion batteries owing to its large capacity (674 mAh g−1) associated with multiple electron transfer. However, the substantial volume swelling and shrinking (≈170%) upon Na uptake and release, which mimics an electrode breathing process, disturbs the structural integrity, leading to poor electrochemical durability and low Coulombic efficiency. Here, a structural strategy to regulate the breathing of CuO nanoarray electrodes during Na cycling using an atomic layer deposition of cohesive TiO2 thin films is presented. CuO nanoarrays are electrochemically grown on 3D Cu foam and directly used as anodes for sodium storage. The regulated CuO electrode arrays enable a large reversible capacity (592 mAh g−1), a high cycle efficiency (≈100%), and an excellent cycling stability (82% over 1000 cycles), which are some of the best sodium storage performance values reported for CuO systems. Electrochemical impedance and microscopic examination reveal that the enhanced performance is a direct outcome of the efficient regulation of the breathing of CuO nanowires by TiO2 layer. [ABSTRACT FROM AUTHOR]

Lithium–sulfur chemistry suffers from poor conversion reaction kinetics, causing low‐capacity utilization of sulfur cathodes, particularly at cryogenic temperatures. Herein, based on low‐cost and abundant commercial sulfur particles directly, a low concentration electrolyte (LCE, 0.1 m) is employed to accelerate lithium–sulfur conversion reaction at low temperatures, demonstrating a broad applicability of this approach. Compared to conventional concentration (1.0 m) electrolytes, the proposed LCE successfully enhances conversion kinetics from Li2S4 to Li2S and restrains shuttle effects of polysulfides, resulting in higher capacity utilizations and more stable cycle performance at 0 and −20 °C. Further interfacial chemistry analyses on cycled electrodes reveal that a hybrid surface layer dominated by organic species as well as some favorable inorganics is constructed in the LCE, demonstrating smaller surface layer resistance. In situ EIS measurements at 0 °C and CV tests reveal main differences of electrode kinetics in 0.1 and 1 m electrolytes, further explaining the differences in working mechanism of two electrolytes. These findings elucidate the roles of LCEs on realizing faster kinetics for cryogenic lithium–sulfur batteries and provide a simple, low‐cost, and widely applicable pathway for achieving high‐performance lithium–sulfur batteries under extreme conditions. [ABSTRACT FROM AUTHOR]