A strategy used to design high capacity (>200 mAh g−1), Li2MnO3-stabilized LiMO2 (M = Mn, Ni, Co) electrodes for lithium-ion batteries is discussed. The advantages of the Li2MnO3 component and its influence on the structural stability and electrochemical properties of these layered xLi2MnO3·(1 −
				x)LiMO2 electrodes are highlighted. Structural, chemical, electrochemical and thermal properties of xLi2MnO3·(1 −
				x)LiMO2 electrodes are considered in the context of other commercially exploited electrode systems, such as LiCoO2, LiNi0.8Co0.15Al0.05O2, Li1+xMn2−xO4 and LiFePO4.

Li2MnO3-stabilized LiMO2 (M = Mn, Ni, Co) electrodes for lithium-ion batteries

Recent advances to develop manganese-rich electrodes derived from ‘composite’ structures in which a Li2MnO3
				(layered) component is structurally integrated with either a layered LiMO2 component or a spinel LiM2O4 component, in which M is predominantly Mn and Ni, are reviewed. The electrodes, which can be represented in two-component notation as xLi2MnO3·(1 −
				x)LiMO2 and xLi2MnO3·(1 −
				x)LiM2O4, are activated by lithia (Li2O) and/or lithium removal from the Li2MnO3, LiMO2 and LiM2O4 components. The electrodes provide an initial capacity >250 mAh g−1 when discharged between 5 and 2.0 V vs. Li0 and a rechargeable capacity up to 250 mAh g−1 over the same potential window. Electrochemical charge and discharge reactions are followed on compositional phase diagrams. The data bode well for the development and exploitation of high capacity electrodes for the next generation of lithium-ion batteries.

Advances in manganese-oxide ‘composite’ electrodes for lithium-ion batteries

Ni-rich layered oxides and Li-rich layered oxides are topics of much research interest as cathodes for Li-ion batteries due to their low cost and higher discharge capacities compared to those of LiCoO2 and LiMn2O4. However, Ni-rich layered oxides have several pitfalls, including difficulty in synthesizing a well-ordered material with all Ni3+ ions, poor cyclability, moisture sensitivity, a thermal runaway reaction, and formation of a harmful surface layer caused by side reactions with the electrolyte. Recent efforts towards Ni-rich layered oxides have centered on optimizing the composition and processing conditions to obtain controlled bulk and surface compositions to overcome the capacity fade. Li-rich layered oxides also have negative aspects, including oxygen loss from the lattice during first charge, a large first cycle irreversible capacity loss, poor rate capability, side reactions with the electrolyte, low tap density, and voltage decay during extended cycling. Recent work on Li-rich layered oxides has focused on understanding the surface and bulk structures and eliminating the undesirable properties. Followed by a brief introduction, an account of recent developments on the understanding and performance gains of Ni-rich and Li-rich layered oxide cathodes is provided, along with future research directions.

Nickel-Rich and Lithium-Rich Layered Oxide Cathodes: Progress and Perspectives

Review on electrode–electrolyte solution interactions, related to cathode materials for Li-ion batteries

Localized surface plasmon resonance (LSPR) in semiconductor nanocrystals (NCs) that results in resonant absorption, scattering, and near field enhancement around the NC can be tuned across a wide optical spectral range from visible to far-infrared by synthetically varying doping level, and post synthetically via chemical oxidation and reduction, photochemical control, and electrochemical control In this review, we will discuss the fundamental electromagnetic dynamics governing light matter interaction in plasmonic semiconductor NCs and the realization of various distinctive physical properties made possible by the advancement of colloidal synthesis routes to such NCs Here, we will illustrate how free carrier dielectric properties are induced in various semiconductor materials including metal oxides, metal chalcogenides, metal nitrides, silicon, and other materials We will highlight the applicability and limitations of the Drude model as applied to semiconductors considering the complex band structures 

Localized Surface Plasmon Resonance in Semiconductor Nanocrystals

The first-order metal-insulator phase transition in VO(2) is characterized by an ultrafast several-orders-of-magnitude change in electrical conductivity and optical transmittance, which makes this material an attractive candidate for the fabrication of optical limiting elements, thermochromic coatings, and Mott field-effect transistors. Here, we demonstrate that the phase-transition temperature and hysteresis can be tuned by scaling VO(2) to nanoscale dimensions. A simple hydrothermal protocol yields anisotropic free-standing single-crystalline VO(2) nanostructures with a phase-transition temperature depressed to as low as 32 degrees C from 67 degrees C in the bulk. The observations here point to the importance of carefully controlling the stoichiometry and dimensions of VO(2) nanostructures to tune the phase transition in this system.

/pdf/depressed-phase-transition-in-solution-grown-vo2-1utvzf830b.pdf

Depressed phase transition in solution-grown VO2 nanostructures.

Soft X-ray (200 to 1000 eV) absorption spectroscopy at the O K-edge and the metal L II,III -edges, in both the fluorescence yield (FY) and the partial electron yield (PEY) mode, has been used to probe the electronic structure of electrochemically deintercalated Li 1-x Ni 05 Mn 05 O 2  FY and PEY spectra of the transition metal L II,III -edges, indicated that Mn ions remain mostly unchanged in the Mn 4+ state at all levels of charge However, the Ni FY L-edge spectra show a continuous shift to higher energy during charge, but remain mostly unchanged in the PEY data The results of the FY data show that the Ni ions in the bulk are oxidized form Ni 2+ to Ni 4+ during charge The difference between the surface-sensitive PEY data and the bulk-sensitive FY data indicates that the surface of Li 1-x Ni 05 Mn 05 O 2 has a different electronic structure than the bulk The shift in the O K-edge to lower energies and the development of a shoulder on the low energy side of the first pre-edge peak indicates that the holes compensating the lithium ion deintercalation are located in O 2p states as well as Ni 3d states These results show that soft X-ray absorption is a powerful technique for studying the electronic structure of new battery materials and it provides unique complementary information to that obtained from hard X-ray (above 1000 eV) absorption studies at the transition metal K-edges

https://iopscience.iop.org/article/10.1149/1.1637896/pdf

Soft X-Ray Absorption Spectroscopic Study of a LiNi0.5Mn0.5 O 2 Cathode during Charge

Hard X-ray photoelectron spectroscopy (HAXPES) provides numerous exciting opportunities to deepen our understanding of materials chemistry and electronic structure, as is evident from recent review...

Zugen Fu

Papers

Depressed phase transition in solution-grown VO2 nanostructures.

Soft X-Ray Absorption Spectroscopic Study of a LiNi0.5Mn0.5 O 2 Cathode during Charge

NIST HAXPES at NSLS and NSLS-II