LiAlO2/LiAl5O8 Membranes Derived from Flame-Synthesized Nanopowders as a Potential Electrolyte and Coating Material for All-Solid-State Batteries

Electrolyte Coatings for High Adhesion Interfaces in Solid-State Batteries from First Principles

We introduce an adhesion parameter that enables rapid screening for materials interfaces with high adhesion. This parameter is obtained by density functional theory calculations of individual single-material slabs rather than slabs consisting of combinations of two materials, eliminating the need to calculate all configurations of a prohibitively vast space of possible interface configurations. Cleavage energy calculations are used as an upper bound for electrolyte and coating energies and implemented in an adapted contact angle equation to derive the adhesion parameter. In addition to good adhesion, we impose further constraints in electrochemical stability window, abundance, bulk reactivity, and stability to screen for coating materials for next-generation solid-state batteries. Good adhesion is critical in combating delamination and resistance to lithium diffusivity in solid-state batteries. Here, we identify several promising coating candidates for the Li7La3Zr2O12 and sulfide electrolyte systems including the previously investigated electrode coating materials LiAlSiO4 and Li5AlO8, making them especially attractive for experimental optimization and commercialization.

Novel LiAlO2 Material for Scalable and Facile Lithium Recovery Using Electrochemical Ion Pumping

In this study, α-LiAlO₂ was investigated for the first time as a Li-capturing positive electrode material to recover Li from aqueous Li resources. The material was synthesized using hydrothermal synthesis and air annealing, which is a low-cost and low-energy fabrication process. The physical characterization showed that the material formed an α-LiAlO₂ phase, and electrochemical activation revealed the presence of AlO₂* as a Li deficient form that can intercalate Li⁺. The AlO₂*/activated carbon electrode pair showed selective capture of Li⁺ ions when the concentrations were between 100 mM and 25 mM. In mono salt solution comprising 25 mM LiCl, the adsorption capacity was 8.25 mg g^-1, and the energy consumption was 27.98 Wh mol Li^-1. The system can also handle complex solutions such as first-pass seawater reverse osmosis brine, which has a slightly higher concentration of Li than seawater at 0.34 ppm.

Zero-Strain Insertion Anode Material of Lithium-Ion Batteries

The insertion type materials are the most important anode materials for lithium-ion batteries, but their insufficient capacity is the bottleneck of practical application. Here, LiAl₅ O₈ nanowires with high theoretical capacity and Li-ions diffusion coefficient are prepared and studied as an insertion anode material, which exhibits zero-strain properties upon electrochemical cycling. However, the poor electronic conductivity of LiAl₅ O₈ definitely sacrifices the capacity and limits the rate performance. Therefore, compact LiAl₅ O₈ and carbon composite are further synthesized, in which nanosized LiAl₅ O₈ particles are uniformly embedded in an amorphous carbon matrix. It displays a reversible capacity of 490.9 mAh g^-1 at 1 A g^-1 , and the capacity rises continuously to 996.8 mAh g^-1 after 1000 cycles due to the interfacial storage mechanism, that the excess Li⁺ ions can be accommodated in the grain boundaries and C/LiAl₅ O₈ interfaces.

Rapid Gas-Phase Synthesis of the Perovskite-Type BaCe0.7Zr0.1Y0.1Yb0.1O3-δ Proton-Conducting Nanocrystalline Electrolyte for Intermediate-Temperature Solid Oxide Fuel Cells

Perovskite-type proton-conducting materials, such as BaCe_0.7Zr_0.1Y_0.1Yb_0.1O_3-δ (BCZYYb), are very attractive for the next-generation equipment of electrochemical energy conversion and storage owing to their excellent conductivity in the intermediate-temperature range (300-750 °C), as well as good thermo-chemical stability, coking resistance, and sulfur tolerance. However, the lack of a reliable and cost-effective synthesis method for such multi-component co-doping oxides limits their large-scale application. In this study, for the first time, we successfully synthesize BCZYYb electrolyte nanopowders by using a rapid, scalable flame-based gas-phase synthesis method with two different barium precursors Ba(NO₃)₂ and Ba(CH₃COO)₂, named as BCZYYb (N) and BCZYYb (CA). The as-synthesized nanoparticles exhibit good crystallinity of the pure orthorhombic perovskite BCZYYb phase. BCZYYb (CA) shows more uniform doping with the element ratio of 1:0.74:0.12:0.08:0.1, which is very close to the theoretical value. The shrinkage and surface SEM (scanning electron microscope) results indicate that the flame-made powders have superior sinterability compared to the sol-gel-made powders because of the smaller primary particle size (∼20 nm). Electrochemical impedance spectroscopy tests show that BCZYYb (CA) sintered at 1450 °C has the highest protonic conductivity of 1.31 × 10^-2 S cm^-1 in wet H₂ when operating at 600 °C and still maintains a high-level conductivity of 1.19 × 10^-2 S cm^-1 even when the sintering temperature is reduced to 1350 °C, which is mainly attributed to uniform doping and good sinterability. The activation energy for the conductivity of BCZYYb (CA) is also significantly lower than that of conventional electrolytes, which suggests much better conductivity in the intermediate (∼600 °C) and even lower operating temperature. The excellent conductivity performance combined with the high-throughput production capability makes the swirling spray flame a promising synthesis method for promoting the BCZYYb electrolytes from lab to industrial-scale solid oxide fuel cells.

Stabilizing High-Voltage Cathodes via Ball-Mill Coating with Flame-Made Nanopowder Electrolytes

LiMn1.5Ni0.5O4 (LMNO) spinel has recently been the subject of intense research as a cathode material because it is cheap, cobalt-free, and has a high discharge voltage (4.7 V). However, the decomposition of conventional liquid electrolytes on the cathode surface at this high oxidation state and the dissolution of Mn2+ have hindered its practical utility. We report here that simply ball-mill coating LMNO using flame-made nanopowder (NPs, 5-20 wt %, e.g., LiAlO2, LATSP, LLZO) electrolytes generates coated composites that mitigate these well-recognized issues. As-synthesized composite cathodes maintain a single P4332 cubic spinel phase. Transmission electron microscopy (TEM) and X-ray photoelectron spectra (XPS) show island-type NP coatings on LMNO surfaces. Different NPs show various effects on LMNO composite cathode performance compared to pristine LMNO (120 mAh g-1, 93% capacity retention after 50 cycles at C/3, ∼67 mAh g-1 at 8C, and ∼540 Wh kg-1 energy density). For example, the LMNO + 20 wt % LiAlO2 composite cathodes exhibit Li+ diffusivities improved by two orders of magnitude over pristine LMNO and discharge capacities up to ∼136 mAh g-1 after 100 cycles at C/3 (98% retention), while 10 wt % LiAlO2 shows ∼110 mAh g-1 at 10C and an average discharge energy density of ∼640 Wh kg-1. Detailed postmortem analyses on cycled composite electrodes demonstrate that NP coatings form protective layers. In addition, preliminary studies suggest potential utility in all-solid-state batteries (ASSBs).

Use of group 13 aryloxides for the synthesis of green chemicals and oxide materials

In this work, group 13 metal aryloxides [Al(MesalO)3] (1), [Me2Ga(MesalO)]2 (2), [AlLi3(MesalO)6] (3) and [Me2GaLi(MesalO)2(THF)] (4), were obtained by reaction of methyl salicylate (MesalOH) with group-13 alkyls MMe3 (for M...

Li7Ba3Al3O11: a new supertetrahedral oxide

Colorless, transparent single crystal grains were obtained from a sample prepared by heating compacts fabricated from mixtures of Li₂O, BaO, and Al₂O₃ powders at 1093 K for 6 h under an Ar atmosphere. Single crystal X-ray diffraction analysis showed that these crystals comprised the new compound Li₇Ba₃Al₃O₁₁ having an orthorhombic cell (lattice constants: a = 13.1706(4), b = 13.1743(4), c = 13.1372(4) Å). The crystal structure of this compound is close to the cubic structure of La₃Cr_9.24N₁₁ (space group Fm3̄m) and contains eight supertetrahedra formed via the vertex-sharing of ten Li-, Li/Al-, and Al-centered oxygen tetrahedra. These supertetrahedra are arranged in the unit cell on the basis of edge-sharing. The crystal symmetry was reduced from cubic Fm3̄m to orthorhombic Pnnn as a result of the partial ordering of Li and Al atoms in the oxygen tetrahedra with various Li/Al site occupancies from 0.0/1.0 to 1.0/0.0. Polycrystalline samples of Li₇Ba₃Al₃O₁₁ were synthesized by heating a mixture of starting materials in the molar ratio corresponding to the stoichiometric composition of Li₇Ba₃Al₃O₁₁ at 1073 K for 6 h under Ar. The electrical conductivity of a polycrystalline sample was determined using the direct current two-terminal method with Li electrodes to be 1.3 × 10^-8 S cm^-1 at 553 K. The estimated activation energy in the range of 553-673 K was 0.88 eV.

In Situ Recombination of Elements in Spent Lithium-Ion Batteries to Recover High-Value γ-LiAlO2 and LiAl5O8

Recovering valuable materials from spent lithium-ion batteries is an important task because of the asymmetry in resource distribution, supply, and demand around the world. A lithium-ion battery is a combination system of various elements and their oxides. Current recovering technologies focus on the separation of valuable metal elements. They can inescapably bring secondary contamination and cost to the environment due to the addition of leachants and precipitants. To recover valuable materials, in situ recombination of elements in spent lithium-ion batteries can be a more economical and environment-friendly solution. Herein, we developed a technology based on in situ aluminothermic reduction and interstitial solid solution transformation to recover high-value γ-LiAlO₂ and LiAl₅O₈ under vacuum and high-temperature (1723 K) conditions. It was found that the process of Li₂O filling into the lattice of O-Al-O structure is an energy-reducing process, while LiAl₅O₈ was an existing high-energy transition-state matter. Since there was no wastewater generated, the process brought a new environment-friendly method for recovering valuable metals from spent lithium-ion batteries. This study also provides new comprehension regarding the design for high-value products' recovery from multi-element mixed wastes on an atomic scale.