The interlayer modification and the intercalation pseudocapacitance have been combined in vanadium oxide electrode for aqueous zinc-ion batteries. Intercalation pseudocapacitive hydrated vanadium oxide Mn 1.4 V 10 O 24 •12H 2 O with defective crystal structure, interlayer water, and large interlayer distance has been prepared by a spontaneous chemical synthesis method. The inserted Mn 2+ forms coordination bonds with the oxygen of the host material and strengthens the interaction between the layers, preventing damage to the structure. Combined with the experimental data and DFT calculation, it is found that Mn 2+ refines the structure stability, adjusts the electronic structure, and improves the conductivity of hydrated vanadium oxide. Also, Mn 2+ changes the migration path of Zn 2+ , reduces the migration barrier, and improves the rate performance. Therefore, Mn 2+ -inserted hydrated vanadium oxide electrode delivers a high specific capacity of 456 mAh g −1 at 0.2 A g -1 , 173 mAh g -1 at 40 A g -1 , and a capacity retention of 80% over 5000 cycles at 10 A g -1 . Furthermore, based on the calculated zinc ion mobility coefficient and Zn(H 2 O) n 2+ diffusion energy barrier, the possible migration behavior of Zn(H 2 O) n 2+ in vanadium oxide electrode has also been speculated, which will provide a new reference for understanding the migration behavior of hydrated zinc-ion.

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Manganese sulfide (MnS) has been found to be a suitable electrode material for lithium-ion batteries (LIBs) owing to its considerable theoretical capacity, high electrochemical activity, and low discharge voltage platform, while its poor electrical conductivity and severe pulverization caused by volume expansion of the material limit its practical application. To improve the rate performance and cycle stability of MnS in LIBs, the structure-control strategy has been used to design and fabricate new anode materials. Herein, the MnS@MXene@CNF (MMC, CNFs means carbon nanofibers) electrode has been prepared by electrospinning and a subsequent high-temperature annealing process. The MMC electrode exhibits excellent cyclic stability with a capacity retention rate close to 100% after 1000 cycles at 1000 mA/g and an improved rate performance with a specific capacity up to 500 mAh/g at a high current density of 5000 mA/g, much higher than the 308 mAh/g of the MnS@CNF (MC) electrode. The elevated electrochemical performance of the MMC electrode not only benefits from the unique structure of MnS nanoparticles evenly dispersed in the well-designed flexible self-supporting three-dimensional (3D) CNF network but, more importantly, also benefits from the formation of sulfur-bridged Mn–S–C bonds at the MnS/MXene interface. The newly formed bonds between MnS and MXene nanosheets can stabilize the structure of MnS near the interfaces and provide a channel for fast charge transfer, which notably increase both the reversibility and the rate of the conversion reaction during the charge/discharge process. This work may pave a new path for designing stable and self-supporting anodes for high-performance LIBs.

The shuttle effect of soluble lithium polysulfides (LiPSs) between electrodes and slow reaction kinetics lead to extreme inefficiency and poor high current cycling stability, which limits the commercial application of Li–S batteries. Herein, the multi-dimensional composite frame has been proposed as the modified separator (MCCoS/PP) of Li–S battery, which is composed of CoS2 nanoparticles on alkali-treated MXene nanosheets and carbon nanotubes. Both experiments and theoretical calculations show that bifunctional catalytic activity can be achieved on the MCCoS/PP separator. It can not only promote the liquid–solid conversion in the reduction process, but also accelerate the decomposition of insoluble Li2S in the oxidation process. In addition, LiPSs shuttle effect has been inhibited without a decrease in lithium-ion transference numbers. Simultaneously, the MCCoS/PP separator with good LiPSs adsorption capability arouses redistribution and fixing of active substances, which is also beneficial to the rate performance and cycling stability. The Li–S batteries with the MCCoS/PP separator have a specific capacity of 368.6 mAh g−1 at 20C, and the capacity decay per cycle is only 0.033% in 1000 cycles at 7C. Also, high area capacity (6.34 mAh cm−2) with a high sulfur loading (7.7 mg cm−2) and a low electrolyte/sulfur ratio (7.5 μL mg−1) is achieved.

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