Synthesis Process of CoSeO3 Microspheres for Unordinary Li-ion Storage Performances and Mechanism of Their Conversion Reaction with Li ions.

Multicomponent materials with various double cations have been studied as anode materials of lithium-ion batteries (LIBs). Heterostructures formed by coupling different-bandgap nanocrystals enhance the surface reaction kinetics and facilitate charge transport because of the internal electric field at the heterointerface. Accordingly, metal selenites can be considered efficient anode materials of LIBs because they transform into metal selenide and oxide nanocrystals in the first cycle. However, few studies have reported synthesis of uniquely structured metal selenite microspheres. Herein, synthesis of high-porosity CoSeO3 microspheres is reported. Through one-pot oxidation at 400 °C, CoSex -C microspheres formed by spray pyrolysis transform into CoSeO3 microspheres showing unordinary cycling and rate performances. The conversion mechanism of CoSeO3 microspheres for lithium-ion storage is systematically studied by cyclic voltammetry, in situ X-ray diffraction and electrochemical impedance spectroscopy, and transmission electron microscopy. The reversible reaction mechanism of the CoSeO3 phase from the second cycle onward is evaluated as CoO + xSeO2 + (1 - x)Se + 4(x + 1)Li+ + 4( x + 1)e- ↔ Co + (2x + 1)Li2 O + Li2 Se. The CoSeO3 microspheres show a high reversible capacity of 709 mA h g-1 for the 1400th cycle at a current density of 3 A g-1 and a high reversible capacity of 526 mA h g-1 even at an extremely high current density of 30 A g-1 .

Yolk-shell-structured microspheres composed of N-doped-carbon-coated NiMoO4 hollow nanospheres as superior performance anode materials for lithium-ion batteries.

Novel yolk-shell-structured microspheres consisting of N-doped-carbon-coated metal-oxide hollow nanospheres are designed as efficient anode materials for lithium-ion batteries and synthesized via a spray pyrolysis process. A NiMoO4 yolk-shell architecture formed via spray pyrolysis is transformed into equally structured NiSe2-MoSe2 composite microspheres. Because of the complementary effect between the Ni and Mo components that prevents severe crystal growth during selenization, NiSe2-MoSe2 nanocrystals are uniformly distributed over the yolk-shell structure. Then, the yolk-shell-structured NiSe2-MoSe2 microspheres are oxidized, which yields microspheres composed of NiMoO4 hollow nanospheres by nanoscale Kirkendall diffusion. Uniform coating with polydopamine and a subsequent carbonization process produce uniquely structured microspheres consisting of N-doped-carbon-coated NiMoO4 hollow nanospheres. The discharge capacity of the yolk-shell-structured NiMoO4-C composite microspheres for the 500th cycle at a current density of 3.0 A g-1 is 862 mA h g-1. In addition, the NiMoO4-C composite microspheres show a high reversible capacity of 757 mA h g-1 even at an extremely high current density of 10 A g-1. The synergetic effect between the hollow nanospheres comprising the yolk-shell structure and the N-doped carbon coating layer results in the excellent lithium-ion storage performance of the NiMoO4-C composite microspheres.

Advances in the synthesis and design of nanostructured materials by aerosol spray processes for efficient energy storage.

The increasing demand for energy storage has motivated the search for highly efficient electrode materials for use in rechargeable batteries with enhanced energy density and longer cycle life. One of the most promising strategies for achieving improved battery performance is altering the architecture of nanostructured materials employed as electrode materials in the energy storage field. Among numerous synthetic methods suggested for the fabrication of nanostructured materials, aerosol spray techniques such as spray pyrolysis, spray drying, and flame spray pyrolysis are reliable, as they are facile, cost-effective, and continuous processes that enable the synthesis of nanostructured electrode materials with desired morphologies and compositions with controlled stoichiometry. The post-treatment of spray-processed powders enables the fabrication of oxide, sulfide, and selenide nanostructures hybridized with carbonaceous materials including amorphous carbon, reduced graphene oxide, carbon nanotubes, etc. In this article, recent progress in the synthesis of nanostructured electrode materials by spray processes and their general formation mechanisms are discussed in detail. A brief introduction to the working principles of each spray process is given first, and synthetic strategies for the design of electrode materials for lithium-ion, sodium-ion, lithium-sulfur, lithium-selenium, and lithium-oxygen batteries are discussed along with some examples. This analysis sheds light on the synthesis of nanostructured materials by spray processes and paves the way toward the design of other novel and advanced nanostructured materials for high performance electrodes in rechargeable batteries of the future.