Advances in physical vapor deposited silicon/carbon based anode materials for Li-ion batteries.

This paper explores the latest developments in physical vapor deposition (PVD) techniques for fabricating silicon-carbon (Si/C) based thin films as anodes of Lithium-Ion batteries (LiBs). Properties of Si/C based materials, such as high thermal stability, electrical conductivity and mechanical strength, have addressed the critical challenges associated with the use silicon as anode material for LiBs, including as volume expansion during lithiation, structural stability and electrode degradation. The review article aims to provide recent advances in the use of Si/C-based thin film materials deposited via PVD processes as anodes for LiBs. PVD deposition processes provide numerous benefits including the precise control over the structure, thickness, morphology, as well as the design of deposited thin-film materials, and this article provides an in-depth analysis on the design and synthesis of Si/C thin films, as well as its electrochemical performance and stability when used as anode for LiBs. The primary aim of this paper is to underscore the advantages provided by PVD processes in overcoming challenges associated with using pure silicon as anode material for LiBs, or in improving the electrochemical performance of Si/C-based anode materials through the design of several Si/C films, covering both multilayer and nanocomposite Si/C film configurations outlined in sections 2 and 3, respectively. Insights into the mechanisms governing lithium-ion insertion/extraction processes within the Si/C matrix are provided, offering an understanding of the material's behavior during battery cycling.

The Electrochemical and Structural Changes of Phosphorus-Doped TiO2 through In Situ Raman and In Situ X-Ray Diffraction Analysis.

Doping is a widely employed technique to enhance the functionality of lithium-ion battery materials, tailoring their performance for specific applications. In our study, we employed in situ Raman and in situ X-ray diffraction (XRD) spectroscopic techniques to examine the structural alterations and electrochemical behavior of phosphorus-doped titanium dioxide (TiO2) nanoparticles. This investigation revealed several notable changes: an increase in structural defects, enhanced ionic and electronic conductivity, and a reduction in crystallite size. These alterations facilitated higher lithiation rates and led to the first observed appearance of LiTiO2 in the Raman spectra due to anatase lithiation, resulting in a reversible double-phase transition during the charging and discharging processes. Furthermore, doping with 2, 5, and 10 wt % phosphorus resulted in an initial increase in specific capacity compared to undoped TiO2. However, higher doping levels were associated with diminished capacity retention, pinpointing an optimal doping level for phosphorus. These results underscore the critical role of in situ characterization techniques in understanding doping effects, thereby advancing the performance of anode materials, particularly TiO2, in lithium-ion batteries.

Sputtered Silicon-Coated Graphite Electrodes as High Cycling Stability and Improved Kinetics Anodes for Lithium Ion Batteries.

Amorphous Si thin films with different thicknesses were deposited on synthetic graphite electrodes by using a simple and scalable one-step physical vapor deposition (PVD) method. The specific capacities and rate capabilities of the produced electrodes were investigated. X-ray diffraction, scanning electron microscopy, Raman spectroscopy, profilometry, cyclic voltammetry, galvanostatic techniques, and in situ Raman spectroscopy were used to investigate their physicochemical and electrochemical properties. Our results demonstrated that the produced Si films covered the bare graphite electrodes completely and uniformly. Si-coated graphite, Si@G, with an optimal thickness of 1 µm exhibited good stability, with an initial discharge capacity of 628.7 mAhg-1, a capacity retention of 96.2%, and a columbic efficiency (CE) higher than 99% at C/3. A discharge capacity of 250 mAh g-1 was attained at a high current rate of 3C, which was over 2.5 times that of a bare graphite electrode, thanks to the high activated surface area (1.5 times that of pristine graphite) and reduced resistance during cycling.

Limiting voltage and capacity fade of lithium-rich, low cobalt Li1.2Ni0.13Mn0.54Fe0.1Co0.03O2 by controlling the upper cut-off voltage.

A new Li1.2Ni0.13Mn0.54Fe0.1Co0.03O2 material with a higher content of Fe and lower content of Co was designed via a simple sol-gel method. Moreover, the effect of upper cut-off voltage on the structural stability, capacity and voltage retention was studied. The Li1.2Ni0.13Mn0.54Fe0.1Co0.03O2 electrode delivers a discharge capacity of 250 mA h g-1 with good capacity retention and coulombic efficiency at 4.6 V cut-off voltage. Importantly, improved voltage retention of 94% was achieved. Ex situ XRD and Raman proved that the electrodes cycled at 4.8 V cut-off voltage showed huge structural conversion from layered-to-spinel explaining the poor capacity and voltage retention at this cut-off voltage. In addition, ex situ FT-IR demonstrates that the upper cut-off voltage of 4.8 V exhibits a higher intensity of SEI-related peaks than 4.6 V, suggesting that reducing the upper cut-off voltage can inhibit the growth of the SEI layer. In addition, when the Li1.2Ni0.13Mn0.54Fe0.1Co0.03O2 cathode was paired with a synthesized phosphorus-doped TiO2 anode (P-doped TiO2) in a complete battery cell, it exhibits good capacity and cycling stability at 1C rate. The material developed in this study represents a promising approach for designing high-performance Li-rich, low cobalt cathodes for next-generation lithium-ion batteries.

High-Valence Surface-Modified LMO Cathode Materials for Lithium-Ion Batteries: Diffusion Kinetics and Operando Thermal Stability Investigation.

Lithium manganese oxide (LiMn2O4) is a prevalent cathode material for lithium-ion batteries due to its low cost, abundant material sources, and ecofriendliness. However, its capacity fade, low energy density, and fast auto-discharge hinders its large-scale commercialization. Consequently, scientists are urged to achieve high-performance LMO cathodes through material doping and surface modification using a wide range of transition metals, polymers, and carbon precursors. Few studies have considered the potential of high-valence transition metal oxides in stabilizing the LMO's cycling process and enhancing the overall battery performance. In this work, we report the synthesis of surface-modified lithium manganese oxide using high-valence tungsten oxide (WVIO3). Different WO3 wt % were investigated before settling for 0.5%WO3-LMO as the synergic surface-modified LMO. Using galvanostatic charge-discharge, 0.50 WO3-LMO exhibited better rate capability by retaining 51% of its initial capacity at a 20C rate, compared to 34% for the pristine LMO. Furthermore, cyclic voltammetry at different scan rates showed that 0.50 WO3-LMO possesses better ion diffusion than pristine LMO, around 10-11 and 10-13 cm2·s-1 respectively. Finally, using in situ Raman spectroscopy, reaction mechanisms during cycling were investigated, and operando accelerating rate calorimetry (ARC) visualized the surface-modified LMO's cycling thermal stability and highlighted its potential use for safe high-voltage lithium-ion batteries in automotive applications.

Elaboration of Lamellar and Nanostructured Materials Based on Manganese: Efficient Adsorbents for Removing Heavy Metals.

The lamellar and nanostructured manganese oxide materials were chemically synthesized by soft and non-toxic methods. The materials showed a monophasic character, symptomatic morphologies, as well as the predominance of a mesoporous structure. The removal of heavy metals Cd(II) and Pb(II) by the synthesized materials Na-MnO2, Urchin-MnO2 and Cocoon-MnO2 according to the mineral structure and nature of the sites were also studied. Kinetically, the lamellar manganese oxide material Na-MnO2 was the most efficient of the three materials which had more vacancies in the MnO6 layers as well as in the space between the layers. The nanomaterials Urchin-MnO2 and Cocoon-MnO2 could exchange with the metal cations in their tunnels and cavities, respectively. The maximum adsorbed quantities followed the order (Pb(II): Na-MnO2 (297 mg/g)?Urchin-MnO2 (264 mg/g)?Cocoon-MnO2 (209 mg/g), Cd(II): Na-MnO2 (199 mg/g)?Urchin-MnO2 (191 mg/g)?Cocoon-MnO2 (172 mg/g)). Na-MnO2 material exhibited the best stability among the different structures, Na-MnO2 presented a very low amount of the manganese released. The results obtained showed the potential of lamellar manganese oxides (Na-MnO2) and nanostructures (Urchin-MnO2 and Cocoon-MnO2) as selective, economical, and stable materials for the removal of toxic metals in an aqueous medium.

A new design of organic radical batteries (ORBs): carbon nanotube buckypaper electrode functionalized by electrografting.

A novel hybrid material displaying a fast and reversible charge storage capability is prepared by electrografting of an alkoxyamine-bearing acrylate onto a carbon nanotube buckypaper, followed by the quantitative generation of an electroactive polynitroxide.

Matrix type transdermal drug delivery systems of metoprolol tartrate: in vitro characterization.

The monolithic matrix type transdermal drug delivery system of metoprolol tartrate were prepared by the film casting on a mercury substrate and characterised in vitro by drug release studies, skin permeation studies and drug-excipients interaction analysis. Four formulations were developed, which differed in the ratio of matrix-forming polymers. Formulations MT-1, MT-2, MT-3 and MT-4 were composed of Eudragit RL-100 and polyvinyl pyrrolidone K-30 with the following ratios: 2:8, 4:6, 6:4 and 8:2, respectively. All the four formulations carried 10% (m/m) of metoprolol tartrate, 5% (m/m) of PEG-400 and 5% (m/m) of dimethyl sulfoxide in isopropyl alcohol: dichloromethane (40:60). Cumulative amounts of the drug released in 48 hours from the four formulations were 61.5, 75.4, 84.3 and 94.5%, respectively. The corresponding values for cumulative amounts of the permeated drug for the said formulations were 53.5, 62.5, 69.8 and 78.2%. On the basis of in vitro drug release and skin permeation performance, formulation MT-4 was found to be better than the other three formulations and it was selected as the optimized formulation.