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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Ultrafast Heterogeneous Nucleation Enables a Hierarchical Surface Configuration of Lithium‐Rich Layered Oxide Cathode Material for Enhanced Electrochemical Performances

Abstract Lithium‐rich layered oxides have attracted much attention for the high energy density, but they still suffer from cycling degradation and sluggish kinetic capability. In the present study, a novel modification of Li 1.143 Mn 0.544 Ni 0.136 Co 0.136 O 2 sphere cathode materials by a hierarchical surface configuration is proposed, which integrates advantages of dual oxide layers of both amorphous and nanocrystalline Al 2 O 3, as well as an inner spinel membrane. Mainly promoted by an ultrafast heterogeneous nucleation of Al(NO) 3 nanoseeds caused by huge solubility differences, it only takes several minutes for pretreatment. After common annealing at low temperature, the obtained material is capable to deliver a high discharge capacity of 296.3 mAh g −1 with initial Coulombic efficiency of 92.9% at 0.1 C rate, and maintain stable cycling at both 0.2 and 0.5 C rates. Besides, rate performances are also enhanced as a result of the superior interface gained after surface modification, which produces reduced polarization during cycling. Through comprehensive analyses, improved surface property and stability are confirmed as the key to these enhancements. This strategy is anticipated to inspire new modification designs in future high energy density cathode materials.

Guo, Haocheng↗
DOE OSTI2025

Etching-assisted upcycling of Ni-lean to Ni-rich cathode materials

Upcycling is recognized as a sustainable recycling approach for spent lithium-ion batteries. However, existing upcycling methods typically involve intricate pretreatment or post-treatment steps, complicating their practical application. Here, in this study, we propose a straightforward, etching-assisted upcycling method that effectively transforms polycrystalline Ni-lean cathodes into high-performance single crystal Ni-rich cathodes. During the etching step, nickel acetate was dissolved into acetic acid and then polycrystalline NMC111 are etched in the solution. Finally, polycrystalline NMC111 are converted into single crystal particles coated with amorphous nickel acetate. This significantly enhances elemental diffusion during subsequent sintering by minimizing both particle size and the contact distance between NMC111 and nickel acetate. As elemental diffusion is improved and acetate ions decompose completely during sintering, the process requires neither additional pretreatment nor post-treatment. The resulting cathode materials (Etched-UP622) exhibit superior structural and electrochemical properties compared to the Control622, achieving an energy density of 719.7 Wh/kg, approximately 56.7 mAh/g higher than Control622 and 125.5 Wh/kg higher than NMC111. Etched-UP622 also delivers higher discharge capacity, improved rate performance and cycling stability, surpassing Control622 and NMC111. Meanwhile, NMC811 also can be synthesized by the proposed strategy, and the discharge capacity can reach 166.9 mAh/g at 1C, similar to 14 mAh/g higher than Control811. Overall, this etching-assisted strategy simplifies the upcycling process and offers a scalable, sustainable route for producing high-quality cathode materials.

Acid etching↗
DOE OSTI2017

Unraveling the Complex Delithiation and Lithiation Mechanisms of the High Capacity Cathode Material V 6 O 13

V 6 O 13 is a promising Li-ion battery cathode material for use in the high temperature oil field environment. The material exhibits a high capacity, and the voltage profile contains several plateaus associated with a series of complex structural transformations, which are not fully understood. The underlying mechanisms are central to understanding and improving the performance of V 6 O 13 -based rechargeable batteries. In this study, we present in situ X-ray diffraction data that highlight an asymmetric six-step discharge and five step charge process, due to a phase that is only formed on discharge. The LixV 6 O 13 unit cell expands sequentially in c , b , and a directions during discharge and reversibly contracts back during charge. The process is associated with change of Li ion positions as well as charge ordering in LixV 6 O 13 . Density functional theory calculations give further insight into the electronic structures and preferred Li positions in the different structures formed upon cycling, particularly at high lithium contents, where no prior structural data are available. Lastly, the results shed light into the high specific capacity of V 6 O 13 and are likely to aid in the development of this material for use as a cathode for secondary lithium batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Low-cobalt and cobalt-free, high-energy cathode materials for lithium batteries

Described herein are low or no-cobalt materials useful as electrode active materials in a cathode for lithium or lithium-ion batteries. For example, compositions of matter are described herein, such as electrode active materials that can be incorporated into an electrode, such as a cathode. The disclosed electrode active materials exhibit high specific energy and voltage, and can also exhibit high rate capability and/or long operational lifetime.

Manthiram, Arumugam↗
DOE OSTI2022

The Effects of Phosphate Impurity on Recovered LiNi 0.6 Co 0.2 Mn 0.2 O 2 Cathode Material via a Hydrometallurgy Method

From portable electronics to electric vehicles, lithium-ion batteries have been deeply integrated into our daily life and industrial fields for a few decades. The booming field of battery manufacturing could lead to shortages in resources and massive accumulation of battery waste, hindering sustainable development. Therefore, hydrometallurgy-based approaches have been widely used in industrial recycling to recover cathode materials due to their high efficiency and throughput. Further, impurities have always been a great challenge for hydrometallurgical recycling, introducing challenges to maintain the consistency of product quality because of potential unintended effects caused by impurities. Herein, after comprehensive investigation, we first report the impacts of phosphate impurity on a recycled LiNi 0.6 Co 0.2 Mn 0.2 O 2 ("NCM622") cathode via a hydrometallurgy method. We demonstrate that a passivation layer of Li 3 PO 4 is formed at grain boundaries during sintering, which significantly raises the activation barrier and hinders lithium diffusion. In addition, the distinct degradation of cathode electrochemical properties is observed from poor particle morphology and high cation mixing as a result of phosphate impurity. Cathode powders with 1 at. % phosphate impurity retain a capacity of 146 mAh/g after 100 cycles at 0.33C, 6% less than that of a virgin cathode. Furthermore, cathodes with higher phosphate concentrations perform even worse in electrochemical tests. Therefore, phosphate impurities are detrimental to the hydrometallurgical recycling of NCM cathode materials and need to be excluded from the recycling process.

25 ENERGY STORAGE↗
DOE OSTI2016

The structural and chemical origin of the oxygen redox activity in layered and cation-disordered Li-excess cathode materials

Lithium-ion batteries are now reaching the energy density limits set by their electrode materials, requiring new paradigms for Li + and electron hosting in solid-state electrodes. Reversible oxygen redox in the solid state in particular has the potential to enable high energy density as it can deliver excess capacity beyond the theoretical transition-metal redox-capacity at a high voltage. Nevertheless, the structural and chemical origin of the process is not understood, preventing the rational design of better cathode materials. We demonstrate how very specific local Li-excess environments around oxygen atoms necessarily lead to labile oxygen electrons that can be more easily extracted and participate in the practical capacity of cathodes. The identification of the local structural components that create oxygen redox sets a new direction for the design of high-energy-density cathode materials.

25 ENERGY STORAGE↗
DOE OSTI2012

Structure and high-temperature properties of the (Sr,Ca,Y)(Co, Mn)O{sub 3-y} perovskites - perspective cathode materials for IT-SOFC

Oxygen deficient perovskites Sr{sub 0.75}Y{sub 0.25}Co{sub 1-x}Mn{sub x}O{sub 3-y}, x=0.5 and 0.75, were prepared by using the citrate route at 1373-1573 K for 48 h. The cubic Pm-3m perovskite structure for x=0.5 was confirmed by electron diffraction study and refined using neutron powder diffraction (NPD) data. For x=0.75, the superstructure corresponding to a={radical}(2) Multiplication-Sign a{sub per}, b=2 Multiplication-Sign a{sub per}, c={radical}(2) Multiplication-Sign a{sub per} (a{sup 0}b{sup -}b{sup -} tilt system, space group Imma) was revealed by electron diffraction. The solid solution Sr{sub 0.75-x}Ca{sub x}Y{sub 0.25}Co{sub 0.25}Mn{sub 0.75}O{sub 3-y}, 0.1{<=}x{<=}0.6 and compound Ca{sub 0.75}Y{sub 0.25}Mn{sub 0.85}Co{sub 0.15}O{sub 2.92} were prepared in air at 1573 K for 48 h. The crystal structure of Ca{sub 0.75}Y{sub 0.25}Mn{sub 0.85}Co{sub 0.15}O{sub 2.92} was refined using NPD data (S.G. Pnma, a=5.36595(4), b=7.5091(6), c=5.2992(4) A, R{sub p}=0.057, R{sub wp}=0.056, {chi}{sup 2}=4.26). High-temperature thermal expansion properties of the prepared compounds were studied in air using both dilatometry and high-temperature X-ray powder diffraction data (HTXRPD). They expanding non-linearly at 298-1073 K due to the loss of oxygen at high temperatures. Calculated average thermal expansion coefficients (TECs) for Sr{sub 0.75}Y{sub 0.25}Co{sub 1-x}Mn{sub x}O{sub 3-y}, x=0.5, 0.75 and Ca{sub 0.75}Y{sub 0.25}Mn{sub 0.85}Co{sub 0.15}O{sub 2.92(1)} are 15.5, 15.1, and 13.8 ppm K{sup -1}, respectively. Anisotropy of the thermal expansion along different unit cell axes was observed for Sr{sub 0.15}Ca{sub 0.6}Y{sub 0.25}Co{sub 0.25}Mn{sub 0.75}O{sub 3-y} and Ca{sub 0.75}Y{sub 0.25}Mn{sub 0.85}Co{sub 0.15}O{sub 2.92}. Conductivity of Sr{sub 0.75}Y{sub 0.25}Co{sub 1-x}Mn{sub x}O{sub 3-y}, x=0.5 and 0.75 increases with the temperature reaching 110 S/cm for x=0.5 and 44 S/cm for x=0.75 at 1173 K. Samples of Sr{sub 0.75-x}Ca{sub x}Y{sub 0.25}Co{sub 0.25}Mn{sub 0.75}O{sub 3-y}, 0.1{<=}y{<=}0.6 were found to be n-type conductors at room temperature with the similar temperature dependence of the conductivity and demonstrated the increase of the {sigma} value from {approx}1 to {approx}50 S/cm as the temperature increases from 300 to 1173 K. Their conductivity is described in terms of the small polaron charge transport with the activation energy (E{sub p}) increasing from 340 to 430 meV with an increase of the calcium content from x=0 to x=0.6. - Graphical abstract: The substitution of cobalt in the 314-phase Sr{sub 0.75}Y{sub 0.25}CoO{sub 2.62} by manganese leads to the formation of oxygen deficient compounds Sr{sub 0.75}Y{sub 0.25}Co{sub 1-x}Mn{sub x}O{sub 3-y}, x=0.5 and 0.75, with the cubic and orthorhombic perovskite structures. The conductivity of the x=0.5 sample (110 S/cm) at 1173 K is substantially higher in comparison with x=0.75 (44 S/cm). Together with comparable TEC values for x=0.5 (15.5 ppm K{sup -1}) and 0.75 (15.1 ppm K{sup -1}) samples this makes the former one a promising cathode material for IT-SOFC. Partial replacement of Sr by Ca in Sr{sub 0.75}Y{sub 0.25}Co{sub 0.25}Mn{sub 0.75}O{sub 3-y} leads to the formation of the solid solution with the orthorhombic perovskite structure, Sr{sub 0.75-x}Ca{sub x}Y{sub 0.25}Co{sub 0.25}Mn{sub 0.75}O{sub 3-y}, 0.1{<=}y{<=}0.6. Along with Sr{sub 0.75}Y{sub 0.25}Co{sub 0.5}Mn{sub 0.5}O{sub 3-y}, novel perovskite Ca{sub 0.75}Y{sub 0.25}Mn{sub 0.85}Co{sub 0.15}O{sub 3-y} represent promising cathode material for IT-SOFC due to low TEC value (13.8 ppm K{sup -1}) and high conductivity of 135 S/cm at 1173 K. Highlights: Black-Right-Pointing-Pointer Mn-doped 314-phases Sr{sub 0.75}Y{sub 0.25}Co{sub 1-x}Mn{sub x}O{sub 3-y}, x=0.5, 0.75 were synthesized. Black-Right-Pointing-Pointer Sr{sub 0.75-x}Ca{sub x}Y{sub 0.25}Co{sub 0.25}Mn{sub 0.75}O{sub 3-y}, x=0.1--0.6, Ca{sub 0.75}Y{sub 0.25}Mn{sub 0.85}Co{sub 0.15}O{sub 3-y} were made. Black-Right-Pointing-Pointer High-temperature conductivity properties and crystal structure were studied. Black-Right-Pointing-Pointer High-temperature thermal expansion behavior was investigated.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Lithium-excess cathode material and co-precipitation formation method

A lithium-excess cathode material according to Li1+xNiaMnbCocModO2−y (0<x<0.3, 0≤a≤1, 0≤b≤1, 0≤c≤1, 0≤d≤0.2, 0≤y≤0.25) in the form of secondary spherical microparticles formed from primary spherical nanoparticles. The primary nanoparticles can in the range of ˜130 nm to 170 nm and the secondary in the range of ˜2-3 μm. A method of formation includes mixing a carbonates or hydroxides solution into a mixed solution of transition metal (M) ions with predetermined stoichiometry under stirring, and aging resulting transition metal carbonates or hydroxides at a predetermined temperature for period of time to produce primary nanoparticles of a predetermined size. A gas-solid interface reaction to uniformly creating oxygen vacancies without affecting structural integrity of Li-excess layered oxides is also provided.

Meng, Ying Shirley↗
DOE OSTI2014

High voltage cathode material for Li-ion batteries

A cathode electrode material for use in rechargeable Li-ion batteries, based on the integration of two Li-based materials of NASICON- and Spinel-type structures, is described in the present invention. The structure and composition of the cathode can be described by a core material and a surface coating surrounding the core material, wherein the core of the cathode particle is of the formula LiMn2-xNixO4−δ (0.5≦x≦0 & 0≦δ≦1) and having a spinel crystal structure, the surface coating is of the formula Li1+xMxTi2-x(PO4)3 (M: is a trivalent cation, 0.5≧x≧0) having a NASICON-type crystal structure.

Hagh, Nader Marandian↗
DOE OSTI2022

Removal of Surface Carbonate from Lithium-Ion Battery Cathode Materials via Vapor-Phase Fluorination

Herein, ultrathin metal-fluoride barrier coatings on the surface of lithium-ion battery (LIB) cathodes can improve cycling stability and prevent corrosion by acidic byproducts in the electrolyte. Atomic layer deposition (ALD) is an effective method to deposit ultrathin metal fluoride coatings on LIB cathodes. Although numerous studies have demonstrated the benefit of ALD metal fluoride coatings to LIB performance, comparatively few works have examined the effect of individual ALD precursors on the cathode surface. This paper uses X-ray photoelectron spectroscopy (XPS) measurements to elucidate the surface chemical changes on LIB cathode material surfaces upon exposure to the ALD metal fluoride precursor, hydrogen fluorine pyridine (HFPy). We found a decrease in surface carbonate and an increase in surface fluoride after HFPy exposure suggesting the conversion of lithium carbonate (Li 2 CO 3 ) to lithium fluoride (LiF). This conversion is desirable given that Li 2 CO 3 degrades LIB performance, whereas LiF provides an excellent physio-chemical barrier against chemical attack during cycling. Scanning transmission electron microscopy, X-ray energy dispersive spectroscopy, and XPS measurements following HFPy exposure to Li 2 CO 3 powder revealed the formation of a conformal LiF shell around the Li 2 CO 3 particles. Finally, we confirmed the complete conversion of similar to 7 nm ALD Li 2 CO 3 films on silicon from HFPy exposure using XPS and spectroscopic ellipsometry. The elimination of problematic Li 2 CO 3 from LIB cathode surfaces and conversion into a protective LiF coating via a single precursor vapor treatment may provide a cost-effective method for enhancing LIB performance.

25 ENERGY STORAGE↗
DOE OSTI2026

Interfacial Chemistry Involved in Selective Separation of NMC/LMO and LCO/LMO Binary Cathode Materials by Froth Flotation Using Oleic Acid

The variability in cathode compositions within recycled lithium-ion battery (LIB) feedstocks poses a significant challenge to efficient downstream refining processes. This study demonstrates the feasibility of using froth flotation with oleic acid as a collector to selectively separate lithium nickel-manganese-cobalt oxide (NMC) and lithium cobalt oxide (LCO) from lithium manganese oxide (LMO) materials. Laboratory-scale flotation tests achieved an 80% separation efficiency in a single stage, producing a froth product with >90% purity of NMC/LCO at approximately 90% yield. Concurrently, the LMO materials were enriched in the sink product with ∼90% purity and ∼90% yield. This approach was further validated using recycled cathode materials, confirming its applicability to realistic feedstocks. The underlying mechanism governing the selective separation of NMC/LCO from LMO was investigated using ζ-potential measurements, contact angle measurements, bubble-particle attachment experiments, and X-ray photoelectron spectroscopy (XPS) analysis. Both contact angle and bubble-particle attachment results confirmed that oleic acid adsorption rendered NMC and LCO surfaces hydrophobic, thereby enhancing flotation recovery. At pH 5, oleic acid adsorbed preferentially onto NMC and LCO surfaces via electrostatic interactions, while exhibiting minimal adsorption on LMO surfaces. However, separation efficiency deteriorated at higher pH, which was attributed to the co-flotation of LMO materials caused by oleate chemisorption on MnOH + species. This work establishes froth flotation as a viable cathode/cathode separation strategy, providing a low-cost, scalable pathway to preconcentrate and enrich nickel-rich and cobalt-rich cathode active materials from incompatible cathode chemistries for direct recycling or hydrometallurgical processing. Furthermore, this study reveals, for the first time, the mechanism of oleate adsorption on the surface of different cathode materials.

PH↗
DOE OSTI2017

Investigation of structural and electrochemical properties of LaSrCo{sub 1−x}Sb{sub x}O{sub 4} (0≤x≤0.20) as potential cathode materials in intermediate-temperature solid oxide fuel cells

The structural and electrochemical properties of the layered perovskite oxides LaSrCo{sub 1−x}Sb{sub x}O{sub 4} (0≤x≤0.20) were investigated to study the effects of substituting Sb for Co for application as cathode materials in intermediate temperature solid oxide fuel cells (IT-SOFCs). The results of crystal structure analyses show the maximum content of Sb in LaSrCo{sub 1−x}Sb{sub x}O{sub 4} to be 0.05 as a pure single phase. XPS shows that Co and Sb in LaSrCo{sub 0.95}Sb{sub 0.05}O{sub 4} may possess mixed-oxidation states. The electrical conductivity increased greatly after Sb substitution. An improvement in the cathode polarization (R{sub p}) values is observed from the Sb-doped sample with respect to the undoped samples. For example, R{sub p} of LaSrCo{sub 0.95}Sb{sub 0.05}O{sub 4} on LSGM was observed to be 0.16 Ω cm{sup 2} at 800 °C in air. The main rate-limiting step for LaSrCo{sub 0.95}Sb{sub 0.05}O{sub 4} cathode is charge transfer of oxygen atoms. These results indicate that Sb can be incorporated into LaSrCo{sub 1−x}Sb{sub x}O{sub 4} based materials and can have a beneficial effect on the performance, making them potentially suitable for use as cathode materials in IT-SOFCs. - Graphical abstract: The oxygen partial pressure dependence of polarization resistances for a new layered perovskite cathode LaSrCo{sub 0.95}Sb{sub 0.05}O{sub 4} at various temperatures was measured. - Highlights: • The maximum content of Sb was 0.05 mol in LaSrCo{sub 1−x}Sb{sub x}O{sub 4}. • The maximum electrical conductivity is 194 S cm{sup −1}for LaSrCo{sub 0.95}Sb{sub 0.05}O{sub 4} at 800 °C. • A rate-limiting process of charge transfer presented.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Infiltrated Sr 0.9 Y 0.1 CoO 2.5+δ nanoparticles as a cathode material for solid oxide fuel cells operated at 450–650 °C

Catalytically active cathode materials are highly desirable for the development of low-temperature solid oxide fuel cells (LT-SOFCs). In the present study, we report the performance of a high-loading Sr 0.9 Y 0.1 CoO 2.5+δ (SYC10) nanoparticles (NPs) as a catalytic cathode infiltrated in Ce 0.8 Gd 0.2 O 2-δ (GDC) backbones for LT-SOFCs and the use of a low-loading SYC10 NPs as a catalyst for promoting the performance of a commercial cathode. The loading and calcination temperature of SYC10 NPs were systematically optimized to achieve the lowest area-specific polarization resistance at ≤650 °C. A significant reduction in polarization resistance of commercial LSCF cathode by SYC NPs has also been demonstrated at 650 °C.

08 HYDROGEN↗
DOE OSTI2019

Synthesis and Characterization of a Molecularly Designed High-Performance Organodisulfide as Cathode Material for Lithium Batteries

An innovative organodisulfide compound, 2,3,4,6,8,9,10,12–Octathia biscyclopenta[b,c]–5,11–anthraquinone–1,7–dithione (TPQD), has been successfully designed, synthesized, and characterized as a cathode material for lithium batteries. A benzoquinone is introduced to coordinate with dithiolane through 1,4–dithianes. The molecular structure, electrochemical performances, and the lithiation/delithiation mechanism of the TPQD cathode have been systematically investigated. TPQD can deliver an initial capacity of 251.7 mAh g -1 at a rate of C/10, which corresponds to the transfer of 4.7 electrons per formula. Highly reversible capacities and stable cyclic performances can be achieved at rates from C/10 to 5 C. Very interestingly, TPQD can retain a capacity of 120 mAh g -1 after 200 cycles at the 5 C rate, which is quite impressive for organodisulfide compounds. X–ray absorption spectroscopy measurements and density functional theory calculation results suggest that such a high capacity is contributed by both O redox of the quinone group and the cleavage and recombination of the disulfide bond. Moreover, the extended π–conjugation structure of the material, introduced by benzoquinone and dithiane, is beneficial for improving the high rate capability and cyclic stability. Furthermore this study illustrates an innovative approach in designing new organodisulfide compounds with improved cyclability and rate capability as cathode materials for high performance lithium batteries.

25 ENERGY STORAGE↗
DOE OSTI2022

Single-Crystalline Ni-Rich LiNi x Mn y Co 1– x – y O 2 Cathode Materials: A Perspective

To drive electrical vehicles for long-range, the energy density of Li-ion batteries must be further enhanced, which requires high-energy cathode materials. Among them, Ni-rich LiNi x Mn y Co 1–x–y O 2 (x > 0.5, NMC) is one of the most promising candidates. However, traditional poly-crystal (PC) NMC materials, whose particles are secondary clusters consisting of many primary crystalline particles, are susceptible to pulverization along the inter grain/particle boundaries, resulting in poor cycle stability. Recently, single crystal (SC)-NMC cathodes are proposed as they are believed to have several merits such as high structural integrity, lower interface with electrolyte, and potentially better energy storage performance. Nevertheless, several queries, such as the merits of SC structure and the mechanism for their structure degradation, are still controversial and required to be addressed. Here, in this study, the synthesis parameters, properties, energy storage as well as safety of SC- and PC-NMC cathodes with various Ni contents are critically reviewed, for clarifying the merits and drawbacks of SC. Furthermore, the study focuses on the recent advances of insight mechanisms and strategies for stabilizing the structure/interface by doping, morphology engineering, surface coating, and composition tailoring. The remaining challenges, safety concerns, and perspectives to enhance the electrochemical performance of SC-NMC cathodes for electric vehicle application are followed.

25 ENERGY STORAGE↗
DOE OSTI2013

Preparation and electrochemical performance of sulfur-alumina cathode material for lithium-sulfur batteries

Highlights: ► Micron-sized alumina was synthesized as adsorbent for lithium-sulfur batteries. ► Sulfur-alumina material was synthesized via crystallizing nucleation. ► The Al{sub 2}O{sub 3} can provide surface area for the deposition of Li{sub 2}S and Li{sub 2}S{sub 2}. ► The discharge capacity of the battery is improved during the first several cycles. - Abstract: Nano-sized sulfur particles exhibiting good adhesion with conducting acetylene black and alumina composite materials were synthesized by means of an evaporated solvent and a concentrated crystallization method for use as the cathodes of lithium-sulfur batteries. The composites were characterized and examined by X-ray diffraction, environmental scanning electron microscopy and electrochemical methods, such as cyclic voltammetry, electrical impedance spectroscopy and charge–discharge tests. Micron-sized flaky alumina was employed as an adsorbent for the cathode material. The initial discharge capacity of the cathode with the added alumina was 1171 mAh g{sup −1}, and the remaining capacity was 585 mAh g{sup −1} after 50 cycles at 0.25 mA cm{sup −2}. Compared with bare sulfur electrodes, the electrodes containing alumina showed an obviously superior cycle performance, confirming that alumina can contribute to reducing the dissolution of polysulfides into electrolytes during the sulfur charge–discharge process.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Reaction Mechanism of the Synthesis of a Disordered Rock Salt Cathode Material

Li-rich disordered rock salt (DRX) materials have recently emerged as a class of promising cathode materials for cobalt- and nickel-free Li-ion batteries that can achieve a high energy density and high electrochemical storage capacity. Here, the synthesis conditions of DRX were found to have a significant impact on the electrochemical performance of the final product formed and hence need to be carefully controlled. To date, the formation pathway of DRX materials has remained largely unexplored. In this work, the phase evolution of a DRX material, Li 1.1 Mn 0.8 Ti 0.1 O 1.9 F 0.1 (LMTF1811), during solid-state synthesis, was monitored using in situ synchrotron X-ray diffraction (sXRD). We have observed several crystalline intermediates formed during the synthesis process before the full formation of DRX. Ex situ X- ray absorption spectroscopy (XAS) was used to assess the local structure and charge states of the transition metals. F K-edge XAS collected from the final product LMTF1811 shows that the degree of F incorporation into the DRX phase is low.

Diffraction↗
DOE OSTI2018

High-Temperature Electrochemical Performance of FeF{sub 3}/C Nanocomposite as a Cathode Material for Lithium-Ion Batteries

Iron trifluoride has been studied as a cathode material due to its cost-effectiveness, low toxicity, and high theoretical capacities of 712 mA h g{sup −1}. However, FeF{sub 3} has serious shortcomings of poor electronic conductivity and a slow diffusion rate of lithium ions, leading to a lower reversible specific capacity. In this work, FeF{sub 3}/C nanocomposite has been synthesized successfully via a high-energy ball-milling method, and acetylene black is used as the conductive agent to improve the conductivity of FeF{sub 3}. The FeF{sub 3}/C nanocomposite shows a high initial discharge capacity of 346.25 and 161.58 mA h g{sup −1} after 40th cycle at 50 mA g{sup −1}. It exhibits good cycle performance and rate performance. The high-temperature discharge capacities decreased with increase in the temperature. The initial high-temperature discharge capacities are found to be 254.17, 300.01, 281.25 and 125.16, and 216.875, 156, 141.67, 150, and 64.98 mA h g{sup −1} at 20th cycles at the 40, 50, 60, and 70 °C, respectively.

77 NANOSCIENCE AND NANOTECHNOLOGY↗