Al2O3 Coating Layer Research Articles

Facile combustion synthesis of amorphous Al2O3-coated LiMn2O4 cathode materials for high-performance Li-ion batteries

The unique Al2O3-coating layer can suppress the Mn dissolution and resist HF corrosion, hence stabilizing the crystal structure of spinel LiMn2O4 cathode materials.

Providing A Long-term Protection for NCM811 Cathode Material by Al2O3 Coating Layer

The degradation of Ni-rich LiNi0.8Co0.1Mn0.1O2 cathode material is successfully suppressed via a facile Al2O3 coating method. The coated Al2O3 layer on the electrode surface is inactive and amorphous, it does not react with the electrolyte and could provide a long-term protection on the electrode during cycling. The electrochemical performance of the modified NCM811 was improved dramatically both at room and elevated temperature. The capacity retention of pristine NCM811 was enhanced from 81.8% to 91.7% when the coating amount reached to 2 wt% at 25°C and much increased from 68.5% to 87.7% at 55°C. Such excellent high temperature performance clearly confirmed the effect of Al2O3 on the structure stability of electrode, it successfully built a favorable protection of the bulk NCM811 from direct contact with electrolyte and suppressed the undesired side reactions.

Al2O3 Coating Layer on the High Temperature Conductive Stability of Pt/ZnO/Al2O3 Film Electrode

Al2O3 Coating Layer on the High Temperature Conductive Stability of Pt/ZnO/Al2O3 Film Electrode

Comparative Study of the Electrochemical Behaviors for LiCoO2 Electrode Coated with Two Different Al2O3 Coating Layer

Comparative Study of the Electrochemical Behaviors for LiCoO2 Electrode Coated with Two Different Al2O3 Coating Layer

A water-based Al2O3 ceramic coating for polyethylene-based microporous separators for lithium-ion batteries

To develop an environmentally friendly and cost-effective water-based inorganic coating process for hydrophobic, polyolefin-based microporous separators, the effect of surfactants in an aqueous inorganic coating solution comprising alumina (Al2O3) on polyethylene (PE)-based microporous separators is investigated. By using a selected surfactant, i.e., disodium laureth sulfosuccinate (DLSS), the aqueous Al2O3 coating solution maintained a dispersed state over time and facilitated the formation of a uniform Al2O3 coating layer on PE separator surfaces. Due to the hydrophilic nature of the Al2O3 coating layers, the as-prepared, ceramic-coated PE separators had better wetting properties, greater electrolyte uptake, and larger ionic conductivities compared to those of the bare PE separators. Furthermore, half cells (LiMn2O4/Li metal) containing Al2O3-coated PE separators showed improved capacity retention over several cycles (93.6% retention after 400 cycles for Al2O3 coated PE separators, compared to 89.2% for bare PE separators operated at C/2) and rate capability compared to those containing bare PE separators. Moreover, because the Al2O3-coated layers are more thermally stable, the coated separators had improved dimensional stability at high temperatures (140 °C).

Low-Cost Al2O3 Coating Layer As a Preformed SEI on Natural Graphite Powder To Improve Coulombic Efficiency and High-Rate Cycling Stability of Lithium-Ion Batteries.

Coulombic efficiency especially in the first cycle, cycling stability, and high-rate performance are crucial factors for commercial Li-ion batteries (LIBs). To improve them, in this work, Al2O3-coated natural graphite powder was obtained through a low-cost and facile sol-gel method. Based on a comparison of various coated amounts, 0.5 mol % Al(NO3)3 (vs mole of graphite) could bring about a smooth Al2O3 coating layer with proper thickness, which could act as a preformed solid electrolyte interface (SEI) to reduce the regeneration of SEI and lithium-ions consumption during subsequent cycling. Furthermore, we examined the advantages of Al2O3 coating by relating energy levels in LIBs using density functional theory calculations. Owing to its proper bandgap and lithium-ion conduction ability, the coating layer performs the same function as a SEI does, preventing an electron from getting to the outer electrode surface and allowing lithium-ion transport. Therefore, as a preformed SEI, the Al2O3 coating layer reduces extra cathode consumption observed in commercial LIBs.

Al2O3-coated porous separator for enhanced electrochemical performance of lithium sulfur batteries

In this paper, Al2O3-coated separator with developed porous channels is prepared to improve the electrochemical performance of lithium sulfur batteries. It is demonstrated that the Al2O3-coating layer is quite effective in reducing shuttle effect and enhancing the stability of the sulfur electrode. The initial discharge capacity of the cell with Al2O3-coated separator can reach 967 mAh g−1 at the rate of 0.2C. After 50th charge/discharge cycle, this cell can also deliver a reversible capacity of as high as 593.4 mAh g−1. Significantly, the charge-transfer resistance of the electrode tends to be reducing after using Al2O3-coated separator. The improved cell performance is attributed to the porous architecture of the Al2O3-coating layer, which serves as an ion-conducting skeleton for trapping and depositing dissolved sulfur-containing active materials, as confirmed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS).

Effects of Al<sub>2</sub>O<sub>3</sub> Coating on the Structural and Electrochemical Performance of LiNi<sub>0.5</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub>O<sub>2</sub> Cathode Material

The pristine LiNi0.5Co0.2Mn0.3O2cathode material particles were successfully coated with Al2O3via a heterogeneous nucleation process and subsequent heat-treatment. The structure and electrochemical properties of Al2O3-coated LiNi0.5Co0.2Mn0.3O2were characterized by XRD and constant-current charge/discharge cycling tests. It was found that the Al2O3coating did not alter the crystal structure of the cathode material. The Al2O3coating layer had a negative influence on the dicharge specific capacity and a positive effect on the cycling performance. The decreased discharge capacity of the coated sample can be attributed to the poor clectronic and ionic conductivity of Al2O3layer, which interfered the Li+intercaltion/deintercaltion into/from the cathode material. The enhanced cycling performance can be ascribed to the suppression of the dissolution of transition metal ions by the HF acid in the eletrolyte and the side reations between electrode and electrolyte by the Al2O3coating layer. The 2wt.% Al2O3-coated sample exhibits the optimal overall electrochemical performance, with discharge specific capacities of 157.0, 137.1 mAh/g at 0.2C and 3C rate, and capacity cycling retention rates of 97.34, 93.53% after 20 & 50 cycles, respectively.

The effect of Al2O3-coating coverage on the electrochemical properties in LiCoO2 thin films

The electrochemical properties of nanoscale Al2O3-coated LiCoO2 thin films were examined as a function of the coating coverage. Al2O3-coated LiCoO2 films showed enhanced cycle-life performance with increasing degree of coating coverage, which was attributed to the suppression of Co dissolution and F− concentration in the electrolyte. Moreover, an Al2O3-coating layer with partial coverage clearly improved the electrochemical properties, even at 60 °C or with a water-contaminated electrolyte. Even though metal-oxide coating on LiCoO2 has been actively investigated, the mechanisms of nanoscale coating have yet to be clearly identified. In this article, surface analysis suggested that the Al2O3-coating layer had transformed to an AlF3 ∙3H2O layer during cycling, which inhibited the generation of HF by scavenging H2O molecules present in the electrolyte.

Role of Alumina Coating on Li−Ni−Co−Mn−O Particles as Positive Electrode Material for Lithium-Ion Batteries

The interface reaction between Al2O3-coated Li[Li0.05Ni0.4Co0.15Mn0.4]O2 and liquid electrolyte was investigated. The Al2O3-coated Li[Li0.05Ni0.4Co0.15Mn0.4]O2 showed no large difference in the bulk structure, comparing to bare Li[Li0.05Ni0.4Co0.15Mn0.4]O2. The coated Al2O3 was found to have an amorphous structure from X-ray diffraction study. A small amount of Al2O3 coating (0.25 wt % in the final composition) showed that a uniform mesoporous Al2O3-coating layer whose thickness is of about 5 nm covers Li[Li0.05Ni0.4Co0.15Mn0.4]O2 particles, as confirmed by transmission electron microscopy. At higher concentration (2.5 wt % in the final composition), the irregular tens of nanometer-sized Al2O3 powders were observed on the surface of the active material instead of the uniform coating layer. Despite the insulating nature of Al2O3, the thin coating was effective to improve the battery performances, depending on the thickness of the Al2O3-coating layer, and used electrolytic salt. The Al2O3 coating resulted i...

Effect of MgO Addition on the Deposition of Al2O3 Coating Layer on Pt Wire by the Electrophoretic Deposition and Sintering of the Layer.

Deposition behavior of MgO-added Al2O3 coating layers on Pt wires by the electrophoretic deposition and sintering of those coating layers were examined. Electrical conductivity of the bath solution and amount of deposited Al2O3 were increased by adding MgO into the bath. Mg (acac)2 (magnesium-acetylacetonate) formed through the reaction of MgO with acetylacetone, which was thermally decomposed to MgO by calcination above 400°C. Crystalline phases in the coating layers sintered at 1500°C changed from α-Al2O3+MgO to α-Al2O3+spinel (MgAl2O4) or spinel+MgO, with increasing the MgO content. It was found that layer shrinking and crack formation depended on the amount of MgO added to the bath. Crack-free sintered thick layers were obtained when more than 10 mass% MgO was incorporated. Thermal decomposition of Mg (acac)2 to MgO, leaving pores in the layer was considered to be the crucial processes to avoid crack-formation in the sintered coatings.