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At least 199 records · Page 11

Origin of structural degradation in Li-rich layered oxide cathode

Li- and Mn-rich (LMR) cathode materials that utilize both cation and anion redox can yield substantial increases in battery energy density 1,2,3 . However, although voltage decay issues cause continuous energy loss and impede commercialization, the prerequisite driving force for this phenomenon remains a mystery 3,4,5,6 In this work, with in situ nanoscale sensitive coherent X-ray diffraction imaging techniques, we reveal that nanostrain and lattice displacement accumulate continuously during operation of the cell. Evidence shows that this effect is the driving force for both structure degradation and oxygen loss, which trigger the well-known rapid voltage decay in LMR cathodes. By carrying out micro- to macro-length characterizations that span atomic structure, the primary particle, multiparticle and electrode levels, we demonstrate that the heterogeneous nature of LMR cathodes inevitably causes pernicious phase displacement/strain, which cannot be eliminated by conventional doping or coating methods. We therefore propose mesostructural design as a strategy to mitigate lattice displacement and inhomogeneous electrochemical/structural evolutions, thereby achieving stable voltage and capacity profiles. These findings highlight the significance of lattice strain/displacement in causing voltage decay and will inspire a wave of efforts to unlock the potential of the broad-scale commercialization of LMR cathode materials.

25 ENERGY STORAGE↗

Developing low-cost rechargeable batteries: beyond traditional layered oxide cathodes for Li-ion and beyond Li-ion batteries

Here, the rising demand for energy storage systems, driven by the rapid adoption of electric vehicles and the global shift toward renewable energy, necessitates continuous efforts to lower the cost of current lithium-ion batteries (LIBs) and enhance the sustainability of existing battery chemistries. This feature article examines the key challenges associated with Ni- and Co-containing LIB cathodes and compares advancements in cathode development for non-traditional Li-ion and beyond Li-ion chemistries. First, a review of earth-abundant element containing disordered rock-salt cathodes is presented, with a discussion of key strategies such as compositional tuning and carbon coating to improve their electrochemical performance. Hurdles in developing oxide-based cathodes for Na- and K-ion batteries are also highlighted, followed by an in-depth overview of polyanion and Prussian blue cathodes for Na- and K-ion systems. Overall, this article provides a systematic perspective on the design of earth-abundant, low-cost, and sustainable cathode materials for both LIB and beyond LIB technologies.

Lohani, Harshita [Lawrence Berkeley National Labor↗

A Numerical Study on the Impact of Cathode Catalyst Layer Loading on the Open Circuit Voltage

The open-circuit voltage (OCV) is the measured potential when no current is drawn from a cell. Additionally, theoretically this potential is given by the equilibrium potential, which is determined from thermodynamics based on the operating conditions. In practice, the actual potential at zero current is measured to be approximately 300 mV lower than the theoretical value.

42 ENGINEERING↗

Mask Free OLED Fabrication Process for Non-Tunable and Tunable White OLED Panels

In this program we demonstrated a method for mask free fabrication of OLEDs. Conventional OLEDs use at least 2 shadowmasks during the fabrication process to define the deposition pattern for the organic layers and for the cathode layer. Although effective, the use of masks requires mask handling and mask change equipment which increases the cost of the OLED deposition system. New sets of masks are required for every new product design, and the mask sets require frequent cleaning as organic material builds up on the masks over time and can be a source of particle defects resulting in yield loss. The method investigated in this program uses laser removal of organic material to pattern the organic layers and define a moisture impermeable seal region. This method is digital and can be applied to any new panel design, avoiding the costs of new masks sets and associated yield loss. In addition, we developed a platform technology for producing white color tunable or dim-to-warm white OLEDs and demonstrated patterning of tunable white OLEDs using the low-cost mask free fabrication process.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Enhancing Oxygen Stability in Low-Cobalt Layered Oxide Cathode Materials by Three-Dimensional Targeted Doping

In this project, we propose to develop a new concept and a generic platform that can lead to the greatly enhanced stabilization of all high-energy cathode materials, and in particular high-nickel (Ni) and low-cobalt (Co) oxides. The new concept is a 3D doping technology that hierarchically combines surface and bulk doping. We will use surface doping to stabilize the surface of primary particles and also introduce dopants in the bulk to further enhance oxygen stability, conductivity, and structural stability in low-Co oxides under high voltage and deep discharging operating conditions. This new concept not only will deliver a low-cost, high-energy cathode but also will provide a generic method that can stabilize all high-energy cathodes. The proposed novel 3D doping approach is poised to resolve some longstanding challenges in fundamental doping effects on battery materials as well as to reduce Li-ion batteries’ cost and improve their safety, energy density, and lifetime. To tackle this problem, we have formed a highly complementary multi-university/national labs/industry team to enable a doping-central and systematic investigation of low-Co materials and create a knowledge base for many electrode materials to be used in advanced electric vehicles. The successful execution of the proposed project relies on five components that can be carried out by the complementary team members: (1) a theoretical investigation of the surface and bulk stabilizing dopants (Persson), (2) a precise synthesis of materials with targeted doping (Lin and Xin), (3) development of electrolytes for high-Ni low-Co oxides (Xu), (4) multi-scale characterization of the structures and their interfaces by scanning transmission electron microscopy (SEM) and synchrotron X-ray imaging and spectroscopy tools (Xin and Lin), and (5) pouch cell-level integration (Fan). The UCI-led project will enable a doping-central and systematic investigation of low-Co materials and create a knowledge base for many electrode materials to be used in advanced electric vehicles.

25 ENERGY STORAGE↗

Cobalt-free layered oxide cathodes

A cathode and a battery providing the cathode is provided. The cathode comprises a lithium metal oxide. The lithium metal oxide comprises nickel, aluminum, and iron. The lithium metal oxide is substantially free of cobalt. The battery comprises an anode, the cathode, a separator, and an electrolyte.

Belharouak, Ilias↗

Atmospheric plasma spraying to fabricate metal‐supported solid oxide fuel cells with open‐channel porous metal support

Abstract Metal‐supported solid oxide fuel cells (MS‐SOFCs) have been fabricated by applying phase‐inversion tape‐casting and atmospheric plasma spraying (APS). The effect of the binder amount of the phase‐inversion slurries on the microstructure development of the 430L stainless steel metal support was investigated. The pore structures, the viscosity of the slurry, porosity and permeability of the as‐prepared metal supports are significantly influenced by the amount of the binder. NiO–scandia‐stabilized zirconia (ScSZ) anode, ScSZ electrolyte and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ (LSCF) cathode layers were consecutively deposited on the metal support with an ideal microstructure by APS process. The effect of plasma power of the APS on the microstructure of the electrolyte and cathode was investigated. A dense electrolyte layer and a porous cathode layer were successfully obtained at 40 and 6 kW of the APS plasma power, respectively. MS‐SOFCs, with a cell configuration of 430L/Ni‐ScSZ/ScSZ/LSCF, achieved a maximum cell power density of 1079 mW cm −2 at 700°C using humidified H 2 as fuel and ambient air as oxidant. The corresponding ohmic resistance and total resistance of MS‐SOFCs was 0.14 and 0.32 Ω cm 2 , respectively. This work demonstrates the feasibility of fabricating high‐performance MS‐SOFCs with economical and scalable techniques.

36 MATERIALS SCIENCE↗

Enabling Structure/Interface Regulation for High Performance Ni-Rich Cathodes

Here, further commercialization of Ni-rich layered cathodes is hindered by severe structure/interface degradation and kinetic hindrance that occur during electrochemical operation, which leads to safety risks and reduced range in electric vehicles (EVs). Herein, by selecting elements with different solubility properties, a multifunctional strategy that synchronously fabricates perovskite-type SrZrO 3 coating and Sr/Zr co-doping is employed to strengthen the structure/interface stability and the Li + transport mobility of LiNi 0.85 Co 0.10 Mn 0.05 O 2 (NCM). Perovskite-type SrZrO 3 protective layers formed on the particle surface can substantially mitigate the unexpected interfacial side reactions and surface phase transitions. In addition, a robust crystal framework is constructed by optimizing local O coordination through the introduction of strong Zr-O bonds. Notably, Li + diffusion kinetics is effectively improved due to expanded cell parameters and O-Li-O slab spacing with the incorporation of large-diameter Sr pillar ions, as revealed by X-ray diffraction. As a result, the Sr/Zr-modified NCM achieves a remarkable capacity retention of 99.4% after 200 cycles at 1 C, and a high rate capacity of 168.9 mAh g -1 at 10 C. This work opens new avenues to develop high-performance NCM cathodes with high energy and high power for EVs with long calendar life.

25 ENERGY STORAGE↗

Substitution-Mediated Calcination of Nickel-Based Cathodes: Decoupling Lithiation and Crystallization

Nickel-based layered cathodes such as LiNiO 2 offer high energy density for lithium-ion batteries, yet improvements in cycling performance and safety are required for practical use–often achieved through manganese and cobalt substitution as in LiNi 0.80 Mn 0.10 Co 0.10 O 2 (NMC811). However, how such substitution impacts calcination, the key process that governs lithiation, structural ordering, crystallization, and ultimately the resulting material properties, remains unclear. Here, in this study, we investigate substitution-mediated calcination dynamics in NMC811 compared to LiNiO 2 using multiscale-correlated in situ spectroscopy and atomistic-to-mesoscale modeling. While both systems progress through the same sequence of intermediates toward the thermodynamically favored layered phase, NMC811 exhibits an earlier onset of layering, concurrent with hydroxide decomposition followed by sluggish crystallization. Modeling reveals that Mn and Co lower the energy barrier for lithium incorporation and ordering but increase the penalty for interlayer gliding, thereby slowing crystal growth at elevated temperatures. This substitution-mediated decoupling of lithiation and crystallization explains the fine-grained microstructure observed in NMC811 versus coarsened particles in LiNiO 2 and establishes a mechanistic framework for predictive microstructure engineering of Ni-based cathodes.

Calcination↗

Probing Dopant Redistribution, Phase Propagation, and Local Chemical Changes in the Synthesis of Layered Oxide Battery Cathodes

Achieving the targeted control of layered oxide properties calls for more fundamental studies to mechanistically probe their evolution during their synthesis. Herein, dopant distribution, phase propagation, and local chemical changes as well as their interplay in multielement-doped LiNiO 2 materials are investigated using spectroscopic, imaging, and scattering techniques. It is shown that dopants undergo dynamic redistribution in the Ni(OH) 2 host lattice at the early stage of calcination (below 300 °C). Such redistribution behavior exhibits strong dopant-dependent characteristics, allowing for targeted surface and bulk doping control. The Ni oxidation process exhibits depth-dependent characteristics and the most rapid Ni oxidation takes place between 300 and 700 °C. Using Ni oxidation state as the proxy for the phase transformation, the buildup of heterogenous phase propagation in the early stage of calcination is shown, especially along the radial direction of secondary particles. Furthermore, the radial heterogenous phase distribution gradually decreases upon completing the calcination. However, a high degree of mosaic-like heterogeneity may still be present in the final product, departing from the perfect layered oxide. Overall, the present study offers fundamental insights into manipulating multiscale materials properties during calcination for obtaining stable, high-energy layered oxide cathodes.

36 MATERIALS SCIENCE↗

Uncommon Behavior of Li Doping Suppresses Oxygen Redox in P2-Type Manganese-Rich Sodium Cathodes

Utilizing both cationic and anionic oxygen redox reactions is regarded as an important approach to exploit high-capacity layered cathode materials with earth abundant elements. It has been popular strategies to effectively elevate the oxygen redox activities by Li-doping to introduce unhybridized O 2p orbitals in Na x MnO 2 -based chemistries or enabling high covalency transition metals in P2-Na 0.66 Mn x TM 1-x O 2 (TM = Fe, Cu, Ni) materials. Here, we investigated the effect of Li doping on regulating the oxygen redox activities P2-structured Na 0.66 Ni 0.25 Mn 0.75 O 2 materials. Systematic X-ray characterizations and ab initio simulations have shown that the doped Li has uncommon behavior in modulating the density of states of the neighboring Ni, Mn and O, leading to the suppression of the existing oxygen and Mn redox reactivities and the promotion of the Ni redox. Furthermore, the findings provide a complementary scenario to current oxygen redox mechanisms and shed lights on developing new routes for high-performance cathodes.

25 ENERGY STORAGE↗

Elastic Lattice Enabling Reversible Tetrahedral Li Storage Sites in a High-Capacity Manganese Oxide Cathode

The key to breaking through the capacity limitation imposed by intercalation chemistry lies in the ability to harness more active sites that can reversibly accommodate more ions (e.g., Li + ) and electrons within a finite space. However, excessive Li-ion insertion into the Li layer of layered cathodes results in fast performance decay due to the huge lattice change and irreversible phase transformation. Here, in this study, an ultrahigh reversible capacity is demonstrated by a layered oxide cathode purely based on manganese. Through a wealth of characterizations, it is clarified that the presence of low-content Li 2 MnO 3 domains not only reduces the amount of irreversible O loss; but also regulates Mn migration in LiMnO 2 domains, enabling elastic lattice with high reversibility for tetrahedral sites Li-ion storage in Li layers. This work utilizes bulk cation disorder to create stable Li-ion-storage tetrahedral sites and an elastic lattice for layered materials, with a reversible capacity of 600 mA h g –1 , demonstrated in th range 0.6–4.9 V versus Li/Li + at 10 mA g –1 . Admittedly, discharging to 0.6 V might be too low for practical use, but this exploration is still of great importance as it conceptually demonstrates the limit of Li-ions insertion into layered oxide materials.

25 ENERGY STORAGE↗

Achieving High Stability and Performance in P2-Type Mn-Based Layered Oxides with Tetravalent Cations for Sodium-Ion Batteries

We report P2-type sodium-manganese-based layered cathodes, owing to their high capacity from both cationic and anionic redox, are a potential candidate for Na-ion batteries to replace Li-ion technology in certain applications. Still, the structure instability originates from irreversible oxygen redox at high voltage remains a challenge. Here, a high sustainability cobalt-free P2- Na 0.72 Mn 0.75 Li 0.24 X 0.01 O 2 (X= Ti/Si) cathode is developed. The outstanding capacity retention and voltage retention after 150 cycles are obtained in Na half-cells. Our finding shows Ti locates on the surface while Si diffuses to the bulk of the particles. Thus, Ti can act as protective layer that alleviate side reactions in carbonate-based electrolyte. Meanwhile, Si can regulate the local electronic structure and suppress oxygen redox activities. Notably, full-cells with hard carbon (≈300-335 Whkg -1 based on the cathode mass) deliver the capacity retention of 83% for P2- Na 0.72 Mn 0.75 Li 0.24 Si 0.01 O 2 and 66% for P2-Na 0.72 Mn 0.75 Li 0.24 Ti 0.01 O 2 after 500 cycles; this electrochemical stability is the best compared to other reported cathodes based on oxygen redox at present. The superior cycle performance also stems from the ability to inhibit microcracking and planar gliding within the particles. Altogether, this finding offers new composition towards developing high performance low-cost cathodes for Na-ion batteries and highlights the unique role of Ti/Si ions.

25 ENERGY STORAGE↗

Mitigating Sodium Ordering for Enhanced Solid Solution Behavior in Layered NaNiO 2 Cathodes

The O-type layered nickel oxides suffer from undesired cooperative Jahn–Teller distortion stemming from Ni 3+ ions and undergo multiple biphasic structural transformations during the insertion/extraction of large Na + ions, posing a significant challenge to stabilize the structural integrity. We present here a systematic investigation of the impact of substituting 5 % divalent (Mg 2+ ) or trivalent (Al 3+ or Co 3+ ) ions for Ni 3+ to alleviate Na + ion ordering and perturb the Jahn–Teller effect to enhance structural stability. Here, we gauge a fundamental understanding of the Mg−O and Na−O or Mg−O−Na bonding interactions, noting that the ionicity of the Mg−O bond deshields the electronic cloud of oxygen from Na + ions. Furthermore, calculations of the Van Vleck distortion modes reveal a relaxation of NiO 6 octahedra from Jahn–Teller distortion and a reduced electron density at the interlayer with Mg 2+ substitution. Long-range (operando X-ray diffraction) and short-range (magic angle spinning nuclear magnetic resonance) structural analyses provide insights into reduced ordering, allowing a stable continuous solid solution. Overall, Mg-substitution results in a high-capacity retention of ~96 % even after 100 cycles, showcasing the potential of this strategy for overcoming the structural instabilities and enhancing the performance of sodium-ion batteries.

25 ENERGY STORAGE↗

Resolving Charge Distribution for Compositionally Heterogeneous Battery Cathode Materials

The isostructural nature of Li-layered cathodes allows for accommodating multiple transition metals (TMs). However, little is known about how the local TM stoichiometry influences the charging behavior of battery particles thus impacting battery performance. In this work, we develop heterogeneous compositional distributions in polycrystalline LiNi 1–x–y Mn x Co y O 2 (NMC) particles to investigate the interplay between local stoichiometry and charge distribution. These NMC particles exhibit a broad, continuous distribution of local Ni/Mn/Co stoichiometry, which does not compromise the global layeredness. The local Mn and Ni concentrations in individual NMC particles are positively and negatively correlated with the electrochemically induced Ni oxidation, respectively, whereas the Co concentration does not impose a clear effect on the Ni oxidation. The resulting material delivers excellent reversible capacity, rate capability, and cycle life at high operating voltages. Engineering Ni/Mn/Co distribution in NMC particles may provide a path toward controlling the charge distribution and thus chemomechanical properties of polycrystalline battery particles.

25 ENERGY STORAGE↗