Xiaojian Ma

TL;DR: Several barium vanadates nanobelts cathodes constructed with two sorts of architectures exhibit superior rate capability and long-term cyclability owing to fast zinc-ion kinetics, which provides a reasonable strategy to engineer cathode materials with robust architectures to improve the electrochemical performance of AZIBs.

Abstract: The intricate charge–discharge reactions and bad conductivity nature of sulfur determine the extreme importance of cathode engineering for Li–S batteries. Herein, spinel ZnCo2O4 porous particles@N‐doped reduced graphene oxide (ZnCo2O4@N‐RGO) are prepared via the combined procedures of refluxing and hydrothermal treatment, consisting of interconnected uniform ZnCo2O4 nanocubes with an average size of 5 nm anchored on graphene nanosheets. The as‐obtained composite can act as an inimitable cathode scaffold to suppress the shuttling of polysulfides by chemical confinement of ZnCo2O4 and N‐RGO for the first time, as demonstrated by the adsorption energy of ZnCo2O4 to Li2S4 via the strong chemical bonding between Zn or Co and S. The RGO nanosheets with a relatively high specific surface area provide a good conductive network and structural stability. The introduction of doped N atoms and numerous ZnCo2O4 porous nanoparticles can inhibit the transfer of lithium polysulfides between the cathode and anode. Due to the unique structural and compositional features, the as‐obtained hybrid materials with the high sulfur loading of 71% and even 82% still deliver high specific capacity, good rate capability, and enhanced cycling stability with exceptionally high initial Coulombic efficiency, which displays a high utilization of sulfur.

Abstract: Despite great breakthroughs, the search for anode materials with high performance for lithium‐ion batteries (LIBs) remains challenging. Hence, engineering advantageous structures via effective routes can bring new possibilities to the development of the LIB field. Herein, the precise synthesis of three‐dimensional (3D) hybrids of ultrathin carbon‐wrapped CoO (CoO@C) dandelions is reported by the pyrolysis of two‐dimensional (2D) Kagóme metal–organic layers (MOLs) at 400 °C under an Ar atmosphere. Due to the special coordination structure of the paternal MOLs, the resulting CoO nanowires show a small diameter of 5–10 nm and are uniformly confined within the ultrathin carbon layer. Based on the time‐dependent pyrolysis experiments, a crystal transformation mechanism of in situ self‐templated‐recrystallization‐self‐assembly accompanied by phase and morphology changes is first presented to reveal the formation of the 3D dandelion‐like spheres with assembly of nanowire arrays from a 2D Kagóme MOL. By virtue of structural and compositional features, including a 3D array structure, the small size of the primary ultrathin nanowires, and a uniform ultrathin graphitic carbon layer, these unique CoO@C dandelions display high specific capacity, good rate capability, and excellent cycling stability. Importantly, this approach can be extended to accurately synthesize other desired composite structures.