Search Results (24)

The global energy shortage and the gradual depletion of lithium resources have become increasingly prominent. Improving the energy density of lithium-based secondary batteries and developing other high-performance alkali-metal secondary batteries have become the research focus. In this study, two-dimensional (2D) hexagonal metal borides (h-MBenes) are investigated as ordered alkali metal adsorption substrates for alkali-metal-based battery anode materials using density functional theory (DFT). Twelve thermodynamically stable h-MBenes are screened out from thirty-three structures, and their excellent stability and metallic electronic characteristics are confirmed. The ordered multilayered growth in alkali metal adsorption is found to depend on two factors: low lattice mismatching and dynamic matching of the work function. In particular, Mg/Al/V-based h-MBenes exhibit excellent lithium lattice matching (<3.35% mismatch), enabling layer-by-layer hexagonal (001) Li growth for ≥5 layers. They have ultrahigh lithium capacities (2170–3818 mAh·g⁻¹), low migration barriers (0.01–0.05 eV), and low voltages (0.003–0.714 V). Mg/Y-based h-MBenes enable three Na layers’ adsorption with a capacity of 1717/605 mAh·g⁻¹, and Al₂B₂ achieves a 472 mAh·g⁻¹ potassium storage capacity, respectively. Due to the orderly multilayered growth mechanism, Mg/Al/V-based h-MBenes show great potential as high-safety and ultrahigh-capacity alkali-metal battery anode materials. Full article

Solid-state lithium batteries are considered ideal due to the safety of solid-state electrolytes. The Na superionic conductor-type Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) is a solid electrolyte with high ionic conductivity, low cost, and stability. However, LATP is reduced upon contact with metallic lithium, leading to lithium dendrite growth on the anode during charging. In this study, LATP was synthesized, and the relationship between crystallinity and ionic conductivity was investigated at different heat treatment temperatures. Optimal sintering conditions and ionic conductivity were analyzed for sintering temperatures from 800 to 1000 °C. To suppress reactions with Li metal, 50 nm thick Ag and 10 nm thick Al₂O₃ layers were deposited on LATP via DC sputtering and plasma-enhanced atomic layer deposition. The electrochemical stability was tested under three conditions: uncoated LATP, Al₂O₃-coated LATP, and Ag+Al₂O₃-coated LATP. The stability improved in the following order: uncoated < Al₂O₃-coated < Ag+Al₂O₃-coated. The Al₂O₃ coating suppressed secondary phase formation by preventing direct contact between LATP and Li, while Ag coating mitigated charge concentration, inhibiting dendrite growth. These findings demonstrate that Ag and Al₂O₃ nano-layers enhance electrolyte stability, advancing solid-state battery reliability and commercialization. Full article

Stabilized Li_6.25La₃Al_0.25 Zr₂O₁₂ (cubic LLZO or c-LLZO) is a Li⁺-conducting ceramic with ionic conductivities approaching 1 mS-cm. Processing c-LLZO so that it is suitable for use as a solid state electrolyte in all solid state batteries, however, is challenging due to the formation of secondary phases at elevated temperatures. The work described in this manuscript examines the formation of one such secondary phase La₂Zr₂O₇ (LZO) formed during sintering c-LLZO at 1000 °C. Specifically, spatially resolved Raman spectroscopy and X-ray Diffraction (XRD) measurements have identified gradients in Li distributions in the Li ion (Li⁺)-conducting ceramic Li_6.25La₃Al_0.25 Zr₂O₁₂ (cubic LLZO or c-LLZO) created by thermal processing. Sintering c-LLZO under conditions relevant to solid state Li⁺ electrolyte fabrication conditions lead to Li⁺ loss and the formation of new phases. Specifically, sintering for 1 h at 1000 °C leads to Li⁺ depletion and the formation of the pyrochlore lanthanum zirconate (La₂Zr₂O₇ or LZO), a material known to be both electronically and ionically insulating. Circular c-LLZO samples are covered on the top and bottom surfaces, exposing only the 1.6 mm-thick sample perimeter to the furnace’s ambient air. Sintered samples show a radially symmetric LZO gradient, with more LZO at the center of the pellet and considerably less LZO at the edges. This profile implies that Li⁺ diffusion through the material is faster than Li⁺ loss through volatilization, and that Li⁺ migration from the center of the sample to the edges is not completely reversible. These conditions lead to a net depletion of Li⁺ at the sample center. Findings presented in this work suggest new strategies for LLZO processing that will minimize Li⁺ loss during sintering, leading to a more homogeneous material with more reproducible electrochemical behavior. Full article

The demand for Li-ion batteries has increased because of their extensive use in vehicles and portable electronic devices. This increasing demand implies greater interaction between batteries and humans, making safety a paramount concern. Although traditional batteries are fabricated using Al, recent efforts to enhance safety have led to the adoption of AISI304. The strength and corrosion resistance of AISI304 are greater than those of Al; however, issues such as stress-induced phase transformation and low high-temperature strength have been observed during processing. Duplex stainless steel SAF2507, which is characterized by a dual-phase structure consisting of austenite and ferrite, exhibits excellent strength and corrosion resistance. Although SAF2507 demonstrated outstanding high-temperature strength up to 700 °C, it precipitated a secondary phase. The precipitation of this secondary phase, believed to be caused by the precipitation of the carbides of Cr and Mo, has been extensively studied. Research on the precipitation of the secondary phase near 1000 °C has been conducted owing to the annealing temperature (1100 °C) of the SAF2507 solution. The secondary phase precipitates at approximately 1000 °C because of slow cooling rates. However, few studies have been conducted on the precipitation of the secondary phase at approximately 700 °C. This study analyzed the precipitation behavior of the secondary phase at 700 °C when SAF2507 was applied and assessed its safety during heat generation in Li-ion batteries. The precipitation behavior was analyzed using field emission scanning electron microscopy for morphology, energy-dispersive X-ray spectroscopy for composition, and X-ray diffraction for phase identification. Full article

Increasing demand to store intermittent renewable electricity from, e.g., photovoltaic and wind energy, has led to much research and development in large-scale stationary energy storage, for example, ZEBRA batteries (Na-NiCl₂ solid electrolyte batteries). Replacing Ni with abundant and low-cost Zn makes the ZEBRA battery more cost-effective. However, few studies were performed on this next-generation ZEBRA (Na-ZnCl₂) battery system, particularly on its AlCl₃-NaCl-ZnCl₂ secondary electrolyte. Its properties such as phase diagrams and vapor pressures are vital for the cell design and optimization. In our previous work, a simulation-assisted method for molten salt electrolyte selection has shown its successful application in development of molten salt batteries. The same method is used here to in-depth study the AlCl₃-NaCl-ZnCl₂ salt electrolyte in terms of its phase diagrams and vapor pressures via FactSage^TM and thermo-analytical techniques (Differential Scanning Calorimetry (DSC) and OptiMelt^TM), and their effects on battery performance such as operation safety and charging/discharging reaction mechanism. The DSC and OptiMelt results show that the experimental data such as melting temperatures and phase changes agree well with the simulated phase diagrams. Moreover, the FactSage^TM simulation shows that the salt vapor pressure increases significantly with increasing temperature and molar fraction of AlCl₃. The obtained phase diagrams and vapor pressures will be used in the secondary electrolyte selection, cell design and battery operation. Full article

Separators play an essential role in lithium (Li)-based secondary batteries by preventing direct contact between the two electrodes and providing conduction pathways for Li-ions in the battery cells. However, conventional polyolefin separators exhibit insufficient electrolyte wettability and thermal stability, and in particular, they are vulnerable to Li dendritic growth, which is a significant weakness in Li-metal batteries (LMBs). To improve the safety and electrochemical performance of LMBs, Al₂O₃ nanoparticles and nanocellulose (NC)-coated non-woven poly(vinylidene fluoride)/polyacrylonitrile separators were fabricated using a simple, water-based blade coating method. The Al₂O₃/NC-coated separator possessed a reasonably porous structure and a significant number of hydroxyl groups (-OH), which enhanced electrolyte uptake (394.8%) and ionic conductivity (1.493 mS/cm). The coated separator also exhibited reduced thermal shrinkage and alleviated uncontrollable Li dendritic growth compared with a bare separator. Consequently, Li-metal battery cells with a LiNi_0.8Co_0.1Mn_0.1O₂ cathode and an Al₂O₃/NC-coated separator using either liquid or solid polymer electrolytes exhibited improved rate capability, cycle stability, and safety compared with a cell with a bare separator. The present study demonstrates that combining appropriate materials in coatings on separator surfaces can enhance the safety and electrochemical performance of LMBs. Full article

Li-Nb-O-based insertion layers between electrodes and electrolytes of Li-ion batteries (LIBs) are known to protect the electrodes and electrolytes from unwanted reactions and to enhance Li transport across interfaces. An improved operation of LIBs, including all-solid-state LIBs, is reached with Li-Nb-O-based insertion layers. This work reviews the suitability of polymorphic Li-Nb-O-based compounds (e.g., crystalline, amorphous, and mesoporous bulk materials and films produced by various methodologies) for LIB operation. The literature survey on the benefits of niobium-oxide-based materials for LIBs, and additional experimental results obtained from neutron scattering and electrochemical experiments on amorphous LiNbO₃ films are the focus of the present work. Neutron reflectometry reveals a higher porosity in ion-beam sputtered amorphous LiNbO₃ films (22% free volume) than in other metal oxide films such as amorphous LiAlO₂ (8% free volume). The higher porosity explains the higher Li diffusivity reported in the literature for amorphous LiNbO₃ films compared to other similar Li-metal oxides. The higher porosity is interpreted to be the reason for the better suitability of LiNbO₃ compared to other metal oxides for improved LIB operation. New results are presented on gravimetric and volumetric capacity, potential-resolved Li⁺ uptake and release, pseudo-capacitive fractions, and Li diffusivities determined electrochemically during long-term cycling of LiNbO₃ film electrodes with thicknesses between 14 and 150 nm. The films allow long-term cycling even for fast cycling with rates of 240C possessing reversible capacities as high as 600 mAhg⁻¹. Electrochemical impedance spectroscopy (EIS) shows that the film atomic network is stable during cycling. The Li diffusivity estimated from the rate capability experiments is considerably lower than that obtained by EIS but coincides with that from secondary ion mass spectrometry. The mostly pseudo-capacitive behavior of the LiNbO₃ films explains their ability of fast cycling. The results anticipate that amorphous LiNbO₃ layers also contribute to the capacity of positive (LiNi_xMn_yCo_zO₂, NMC) and negative LIB electrode materials such as carbon and silicon. As an outlook, in addition to surface-engineering, the bulk-engineering of LIB electrodes may be possible with amorphous and porous LiNbO₃ for fast cycling with high reversible capacity. Full article

Layered lithium transition metal (TM) oxides LiTMO₂ (TM = Ni, Co, Mn, Al, etc.) are the most promising cathode materials for lithium-ion batteries because of their high energy density, good rate capability and moderate cost. However, the safety issue arising from the intrinsic thermal instability of nickel-based cathode materials is still a critical challenge for further applications in electric vehicles and energy storage power stations. The main reasons include side reactions between the highly reactive Ni^3+/4+ and liquid electrolyte, oxygen release accompanied by structural phase transition, and internal microcrack propagation owing to the low strength of spherical secondary particles. Great efforts have been invested to modify nickel-based cathode materials such as stabilization of bulk structure by element doping, surface engineering, nanostructure design, and particle mono-crystallization. In this review, we summarize these advances and try to give an in-depth insight into the origin of the thermal instability of nickel-based cathode materials. More importantly, some effective strategies to improve thermal stability are outlined, expecting to accelerate the future development of layered TM oxides with high safety. Full article

Replacing liquid electrolytes with solid-state conductors is one of the key challenges to increasing the safety and energy density of next-generation Li secondary batteries. In this work, the NASICON-type Li_1+xAl_xZr_yTi_2−x−y(PO₄)₃ with 0 ≤ x, y ≤ 0.2 solid electrolytes were synthesized using solid-state and sol-gel techniques at various sintering temperatures (800, 900, and 1000 °C). Their morphology and conducting properties were studied to determine the optimal dopant content and synthesis method. Li_1.2Al_0.2Zr_0.1Ti_1.7(PO₄)₃ and Li_1.1Al_0.1Zr_0.2Ti_1.7(PO₄)₃ prepared at 900 °C using a solid-state reaction exhibit the highest total conductivity at 25 °C (7.9 × 10⁻⁴ and 5.4 × 10⁻⁴ S cm⁻¹, respectively), which is due to the optimal size of lithium transport channels, as well as the high density of these samples. The potential profile of Li|Li_1.2Al_0.2Zr_0.1Ti_1.7(PO₄)₃|Li cells was retained during cycling at a current density of 0.05 mA cm⁻² for 100 h, indicating a high interfacial Li metal/electrolyte stability. Full article

With advancements in the automotive industry, the demand for electric vehicles (EVs) has remarkably increased in recent years. However, the EV battery, which is a vital part of the EV, poses certain challenges that limit the performance of the EVs. The joining of dissimilar materials for different components affects the electrical and mechanical performances of EV batteries. Laser beam welding is a promising technique for joining Al and Cu for application in secondary battery fabrication because of the precise control over heat input and high process speed. However, the production of Al–Cu joints remains challenging because of the differences between their thermal and metallurgical properties and the resulting formation of brittle and hard intermetallic compounds, which reduce mechanical and electric properties. Thus, it is vital to characterize the weld to improve joint performance and enhance the laser welding process. This study investigates the joining of an Al alloy (AA1050) with Ni-coated Cu using a continuous-wave Yb fiber laser. The evaluation of the weld morphology showed a correlation between the weld characteristics and process parameters (laser power and welding speed). The weld interface width and penetration depth into the lower sheet (Cu) both increased with increasing heat input. Optical microscopy of the weld cross-section revealed many defects, such as voids and cracks. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) was employed to examine the weld microstructure. The composition analysis revealed the presence of mixed morphology of Al–Cu eutectic alloy (α-Al+Θ-Al2Cu) phase in the form of dendrites in the weld fusion zone with traces of the highly brittle Al4Cu9 phase at a high heat input condition. Furthermore, the electrical contact resistance of the weld seam was measured to determine the correlation between heat input and resistance. In addition, Vickers microhardness measurements were performed on the weld cross-section to validate the SEM/EDS results. Full article

Developing uniform ceramic-coated separators in high-energy Li secondary batteries has been a challenging task because aqueous ceramic coating slurries have poor dispersion stability and coating quality on the hydrophobic surfaces of polyolefin separators. In this study, we develop a simple but effective strategy for improving the dispersion stability of aqueous ceramic coating slurries by changing the mixing order of the ceramic slurry components. The aqueous ceramic coating slurry comprises ceramics (Al₂O₃), polymeric binders (sodium carboxymethyl cellulose, CMC), surfactants (disodium laureth sulfosuccinate, DLSS), and water. The interaction between the ceramic slurry components is studied by changing the mixing order of the ceramic slurry components and quantitatively evaluating the dispersion stability of the ceramic coating slurry using a Lumisizer. In the optimized mixing sequence, Al₂O₃ and DLSS premixed in aqueous Al₂O₃-DLSS micelles through strong surface interactions, and they repel each other due to steric repulsion. The addition of CMC in this state does not compromise the dispersion stability of aqueous ceramic coating slurries and enables uniform ceramic coating on polyethylene (PE) separators. The prepared Al₂O₃ ceramic-coated separators (Al₂O₃–CCSs) exhibit improved physical properties, such as high wettability electrolyte uptake and ionic conductivity, compared to the bare PE separators. Furthermore, Al₂O₃–CCSs exhibit improved electrochemical performance, such as rate capability and cycling performance. The half cells (LiMn₂O₄/Li metal) comprising Al₂O₃–CCSs retain 90.4% (88.4 mAh g⁻¹) of initial discharge capacity after 150 cycles, while 27.6% (26.4 mAh g⁻¹) for bare PE. Furthermore, the full cells (LiMn₂O₄/graphite) consisting of Al₂O₃–CCSs exhibit 69.8% (72.2 mAh g⁻¹) of the initial discharge capacity and 24.9% (25.0 mAh g⁻¹) for bare PE after 1150 cycles. Full article

Lithium-ion batteries (LIBs) are dangerous to recycle, as they pose a fire hazard when cut and contain various chemical hazards. If recycled safely, LIBs provide a rich secondary source for metals such as lithium and cobalt, while reducing the environmental impact of end-of-life LIBs. Discharging the spent LIBs in a 5 wt.% NaCl electrolyte at room temperature enables their safe dismantling. A sludge was observed to form during the LIB discharging, with a composition of 34.9 wt.% Fe, 35 wt.% O, 17.7 wt.% Al, 6.2 wt.% C, and 4.2 wt.% Na. The average electrolytic solution composition after the first discharge cycle contained only 12.6 mg/L Fe, 4.5 mg/L Li, 2.5 mg/L Mn, and trace amounts of Ni and Co. Separating the active cathode powder from the aluminum cathode with a 10 wt.% NaOH leach produced an aqueous filtrate with an Al metal purity of 99.7%. The leach composition consisted of 9558 mg/L Al, 13 mg/L Li, 8.7 mg/L Co, and trace amounts of Mn and Ni. The hydrometallurgical sample preparation processes in this study enables the production of a pure black mass with less than 0.05 wt.% Co, 0.2 wt.% Li, 0.02 wt.% Mn, and 0.02 wt.% Ni losses from the active cathode material. Full article

The next generation of all-solid-state batteries can feature battery safety that is unparalleled among conventional liquid batteries. The garnet-type solid-state electrolyte Li₇La₃Zr₂O₁₂ (LLZO), in particular, is widely studied because of its high Li-ion conductivity and stability in air. However, the poor interface-contact between Li and the electrolyte (garnet) severely limits the development of solid electrolytes. In this study, we synthesize cubic phase Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) using a secondary sintering method. In addition, a thin aluminum nitride (AlN) layer is introduced between the metal (Li) and the solid electrolyte. Theoretical calculations show that AlN has a high affinity for Li. Furthermore, it is shown that the AlN coating can effectively reduce the interface impedance between Li and the solid electrolyte and improve the lithium-ion transport. The assembled symmetric Li cells can operate stably for more than 3600 h, unlike the symmetric cells without AlN coating, which short-circuited after only a few cycles. The hybrid solid-state battery with a modified layer, which is assembled using LiFePO₄ (LFP), still has a capacity of 120 mAh g⁻¹ after 200 cycles, with a capacity retention rate of 98%. This shows that the introduction of an AlN interlayer is very helpful to obtain a stable Li/solid-electrolyte interface, which improves the cycling stability of the battery. Full article

In this study, industrial lithium-ion battery (LIB) waste was treated by a froth flotation process, which allowed selective separation of electrode particles from metallic-rich fractions containing Cu and Al. In the flotation experiments, recovery rates of ~80 and 98.8% for the cathode active elements (Co, Ni, Mn) and graphite were achieved, respectively. The recovered metals from the flotation fraction were subsequently used in high-temperature Cu-slag reduction. In this manner, the possibility of using metallothermic reduction for Cu-slag reduction using Al-wires from LIB waste as the main reductant was studied. The behavior of valuable (Cu, Ni, Co, Li) and hazardous metals (Zn, As, Sb, Pb), as a function of time as well as the influence of Cu-slag-to-spent battery (SB) ratio, were investigated. The results showcase a suitable process to recover copper from spent batteries and industrial Cu-slag. Cu-concentration decreased to approximately 0.3 wt.% after 60 min reduction time in all samples where Cu/Al-rich LIB waste fraction was added. It was also showed that aluminothermic reduction is effective for removing hazardous metals from the slag. The proposed process is also capable of recovering Cu, Co, and Ni from both Cu-slag and LIB waste, resulting in a secondary Cu slag that can be used in various applications. Full article

The recovery of technically important elements like lithium from slag of pyrometallurgical recycling of lithium traction batteries will be very important in future due to the expected increasing demand of this element with the upcoming world-wide implementation of electro mobility. Therefore, the investigation of possibilities to recover lithium from pyrometallurgical slag from the recycling of lithium traction batteries is mandatory. In this context, the EnAM (engineered artificial mineral) approach is very promising. Solidified melt of synthetic recycling slag with the compounds Li₂O-MgO-Al₂O₃-SiO₂-CaO-MnO contains various Li-bearing phases including spinel solid solution, Li-aluminate and eucryptite-like Li-alumosilicate. Most probably, the Ca-alumosilicate matrix (melilite-like solid solution) incorporates lithium as well. These compounds can be determined and calculated to an acceptable approximation with electron probe microanalysis (EPMA). Nevertheless, an adequate precise measurement of lithium is virtually impossible due to the extremely low fluorescence yield and long wavelength of Li Kα. Secondary mass spectrometry (SIMS) can be used to fill this gap in the analytical assessment of the slag. Therefore, the combination of these two analytical methods can distinctively improve the mineralogical and chemical characterization of lithium-containing solidified (slag) melt. Full article