Tailored Design of a Nanoporous Structure Suitable for Thick Si Electrodes on a Stiff Oxide-Based Solid Electrolyte.

Oxide-based all-solid-state batteries are ideal next-generation batteries that combine high energy density and high safety, but their realization requires the development of interface bonding technology between the stiff solid electrolyte and electrode. Even if the interface could be bonded, it is difficult to hold the interface, because only the electrode expands/contracts unilaterally during charge/discharge reactions. In particular, silicon (Si), which has eagerly awaited as a next-generation negative-electrode material for many years, changes in volume by several hundred percent.

Non-Flammable and Highly Concentrated Carbonate Ester-Free Electrolyte Solutions for 5 V-Class Positive Electrodes in Lithium-Ion Batteries.

Non-flammable and highly concentrated electrolyte solutions were designed using tris(2,2,2-trifluoroethyl) phosphate (TFEP) as a main solvent toward a radical improvement in the safety and energy density of lithium-ion batteries. Unlike conventional carbonate ester-based solutions, simple TFEP-based electrolyte solutions were not intrinsically compatible with 5 V-class LiNi Mn O positive electrodes, even at high concentrations. Based on the degradation mechanism that was analyzed by Raman spectroscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy, a fluorinated diluent of methyl 3,3,3-trifluoropropionate (FMP) was introduced to suppress the decomposition of LiBF and TFEP at high potentials.

Effect of Lithium Silicate Addition on the Microstructure and Crack Formation of LiNiCoMnO Cathode Particles.

The microstructure of LiNiCoMnO cathode materials was controlled by the addition of lithium silicate, and the influence on the cycle performance and the rate capability was investigated. Si was not included within the lattice, but localized at the grain boundaries of the primary particles and the pores inside the secondary particles. The addition of the lithium silicate greatly decreased the density of the pores between the primary particles and improved the density of the secondary particles.

Artificial lithium fluoride surface coating on silicon negative electrodes for the inhibition of electrolyte decomposition in lithium-ion batteries: visualization of a solid electrolyte interphase using in situ AFM.

The solid electrolyte interphase (SEI), which is a surface layer formed on the negative electrode, plays an important role in inhibiting the reductive decomposition of the electrolyte solution in a lithium-ion battery. However, it has not been understood well which components are important for the SEI to prevent the electrolyte decomposition. Lithium fluoride (LiF), as an artificial SEI, was formed on an amorphous-Si thin film by physical vapor deposition.

In situ Scanning Electron Microscopy of Silicon Anode Reactions in Lithium-Ion Batteries during Charge/Discharge Processes.

A comprehensive understanding of the charge/discharge behaviour of high-capacity anode active materials, e.g., Si and Li, is essential for the design and development of next-generation high-performance Li-based batteries.

Analysis of cationic structure in some room-temperature molten fluorides and dependence of their ionic conductivity and viscosity on hydrofluoric acid concentration.

To understand the ionic and nonionic species in (CH(3))(4)NF·mHF, (CH(3))(3)N·mHF, (C(2)H(5))(4)NF·mHF, and (C(2)H(5))(3)N·mHF melts, the structures of these melts were investigated by infrared spectroscopy, NMR, and high-energy X-ray diffraction. Infrared spectra revealed that three kinds of fluorohydrogenate anions, (FH)(n)F(-) (n = 1, 2, and 3), and molecular hydrofluoric acid (HF) are present in every melt. Ionic conductivity and viscosity of these melts were measured and correlated with their cationic structure.

Preparation of core/shell and hollow nanostructures of cerium oxide by electrodeposition on a polystyrene sphere template.

Core/shell nanostructures of polystyrene (PS)/CeO2 have been prepared on conductive glass substrates by using a novel electrochemical route consisting of (i) the electrophoretic deposition of a PS sphere monolayer on the substrate and (ii) the following potentiostatic electrodeposition of CeO2 on the PS sphere template in Ce(NO3)3 aqueous solutions. The structural morphologies of the deposit changed drastically depending on the Ce(NO3)3 concentration; i.e.

Atomic force microscopy study on the stability of a surface film formed on a graphite negative electrode at elevated temperatures.

The stability at elevated temperatures of a solid electrolyte interphase (SEI) formed on a graphite negative electrode in lithium ion batteries was investigated by storage tests and in situ atomic force microscopy (AFM) observation. When the fully discharged graphite electrode was stored at elevated temperatures, the irreversible capacity in the following cycle increased remarkably. On the other hand, when the electrode was stored at the fully charged state at elevated temperatures, it was severely self-discharged during storage.