Stabilizing Lithium-Sulfur Batteries through Control of Sulfur Aggregation and Polysulfide Dissolution.

Lithium-sulfur (Li-S) batteries are investigated intensively as a promising large-scale energy storage system owing to their high theoretical energy density. However, the application of Li-S batteries is prevented by a series of primary problems, including low electronic conductivity, volumetric fluctuation, poor loading of sulfur, and shuttle effect caused by soluble lithium polysulfides. Here, a novel composite structure of sulfur nanoparticles attached to porous-carbon nanotube (p-CNT) encapsulated by hollow MnO2 nanoflakes film to form p-CNT@Void@MnO2 /S composite structures is reported. Benefiting from p-CNTs and sponge-like MnO2 nanoflake film, p-CNT@Void@MnO2 /S provides highly efficient pathways for the fast electron/ion transfer, fixes sulfur and Li2 S aggregation efficiently, and prevents polysulfide dissolution during cycling. Besides, the additional void inside p-CNT@Void@MnO2 /S composite structure provides sufficient free space for the expansion of encapsulated sulfur nanoparticles. The special material composition and structural design of p-CNT@Void@MnO2 /S composite structure with a high sulfur content endow the composite high capacity, high Coulombic efficiency, and an excellent cycling stability. The capacity of p-CNT@Void@MnO2 /S electrode is ≈599.1 mA h g-1 for the fourth cycle and ≈526.1 mA h g-1 after 100 cycles, corresponding to a capacity retention of ≈87.8% at a high current density of 1.0 C.

Graphene-Like Carbon Film Wrapped Tin (II) Sulfide Nanosheet Arrays on Porous Carbon Fibers with Enhanced Electrochemical Kinetics as High-Performance Li and Na Ion Battery Anodes.

SnS, is a promising anode material for lithium ion batteries (LIBs) and sodium ion batteries (SIBs), however, undergoes poor cyclic lifespan due to its huge volume changes and bad electroconductivity. Here, a modified CVD method is used to directly grow graphene-like carbon film on the surface of SnS nanosheet arrays which are supported by Co-, N-modified porous carbon fibers (CCF@SnS@G). In the strategy, the SnS nanosheet arrays confined into the integrated carbon matrix containing porous carbon fibers and graphene-like carbon film, perform a greatly improved electrochemical performance. In situ TEM experiments reveal that the vertical graphene-like carbon film can not only protect the SnS nanosheet from destruction well and enhance the conductivity, but also transforms SnS nanosheet into ultrafine nanoparticles to promote the electrochemical kinetics. Systematic electrochemical investigations exhibit that the CCF@SnS@G electrode delivers a stable reversible capacity of 529 mAh g-1 at a high current density of 5 A g-1 for LIBs and 541.4 mAh g-1 at 2 A g-1 for SIBs, suggesting its good potential for anode electrodes.

Humid atmospheric pressure plasma jets exposed micro-defects on CoMoO4 nanosheets with enhanced OER performance.

Humid atmospheric pressure plasma jets (APPJs) sustained in an argon/water vapour mixture were adopted to treat CoMoO4 nanosheets arrays, which resulted in micro-defects on the surface and the appearance of hydroxyl (OH-) groups absorbed on the nanosheets. Benefiting from these changes, the plasma treated CoMoO4 exhibited similar catalytic property to RuO2, an overpotential 70 mV lower than for pristine CoMoO4 and maintained good stability after 30 hours for the water oxidation.

Hollow Co3O4@MnO2 Cubic Derived From ZIF-67@Mn-ZIF as Electrode Materials for Supercapacitors.

Hollow Co3O4@MnO2 cubic nanomaterials are synthesized by ZIF-67@Mn-ZIF sacrificial precursor through a facile thermal treatment. As a kind of supercapacitor electrode material, it demonstrates high performances, such as specific capacitance of 413 F g-1 at the current density of 0.5 A g-1; as the current densities raised from 0.5 to 10 A g-1 (20 times increasing), there is still ~41% retention of its initial capacitance. These satisfactory electrochemical properties should be put down to the hollow and porous structure and the relative higher BET surface area, which supplies more reactive sites for charge and discharge processes.

Hollow Cu-doped NiO microspheres as anode materials with enhanced lithium storage performance.

Doping is an effective way to optimize the properties of electrode materials. In this study, hollow Cu-doped NiO microspheres were obtained via the hydrothermal method, in which the microspheres were aggregated from nanoparticles. Compared with the original NiO electrode, the Cu-doped NiO electrode exhibits prominent initial capacity (1180 vs. 900 mA h g-1) and better rate capability (80% vs. 30% retention) as anode materials. The superior electrochemical properties could be attributed to the enhanced conductivity by Cu doping.