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At least 1,099 records · Page 61

Cracking the failure of lithium batteries

Lithium batteries that use a solid electrolyte have the potential to improve safety and increase the amount of stored energy . This makes solid-state electrochemical cells a promising option for electric vehicles and wearable devices. However, nonuniform plating or stripping of lithium at the interface between an anode (negative electrode) and the electrolyte during charging and discharging leads to growth of detrimental lithium filaments (dendrites) that short-circuit the battery cell. This problem even occurs when the battery operates at small currents. The underlying mechanism of this failure is not well understood. On page 311 of this issue, Wang et al. (1) report that structural defects accumulate in the lithium metal anode under repeated charging and discharging at a small current. This is similar to mechanical fatigue that is observed over longer periods of intermittent straining of a material. Here, the observation could guide the design of lithium batteries with increased life span.

25 ENERGY STORAGE↗

Recent Developments and Challenges in Hybrid Solid Electrolytes for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) have attracted worldwide research interest due to their high energy density and long cycle life. Solid-state LIBs improve the safety of conventional liquid-based LIBs by replacing the flammable organic electrolytes with a solid electrolyte. Among the various types of solid electrolytes, hybrid solid electrolytes (HSEs) demonstrate great promise to achieve high ionic conductivity, reduced interfacial resistance between the electrolyte and electrodes, mechanical robustness, and excellent processability due to the combined advantages of both polymer and inorganic electrolyte. This article summarizes recent developments in HSEs for LIBs. Approaches for the preparation of hybrid electrolytes and current understanding of ion-transport mechanisms are discussed. The main challenges including unsatisfactory ionic conductivity and perspectives of HSEs for LIBs are highlighted for future development. The present review provides insights into HSE development to allow a more efficient and target-oriented future endeavor on achieving high-performance solid-state LIBs.

25 ENERGY STORAGE↗

Trapping and imaging dynamic battery nanointerfaces via electrified cryo-EM

The electrified interface between a liquid and a solid underpins diverse phenomena, from ion-transfer during battery operation to action potentials enabling biological communication. However, conventional tools are blind to the nanoscale dynamics of this metastable interface. Here, we leverage electrified cryo–electron microscopy (eCryo-EM), a technique that rapidly freezes and kinetically traps these dynamic, nonequilibrium states during battery operation for nanoscale characterization. Collective snapshots of the electrified interface at controlled time intervals quantifies early-stage growth kinetics of the solid electrolyte interphase (SEI), a passivation film that governs electron and ion transport. Unexpectedly, the diffusivity of charged species of the two SEI films with differing chemistry and performance are estimated to be within 10% of the other, indicated by the slope of their diffusion-limited SEI growth regimes. Instead, the slope of the reaction-limited SEI growth regimes differs by a factor of 3, suggesting that lowered reactivity of the high-performance electrolyte is largely responsible for its high coulombic efficiency.

Science & Technology - Other Topics↗

Effect of particle size on thermodynamics and lithium ion transport in electrodes made of Ti 2 Nb 2 O 9 microparticles or nanoparticles

This study compares the charging mechanisms, thermodynamics, lithium ion transport, and operando isothermal calorimetry in lithium-ion battery electrodes made of Ti 2 Nb 2 O 9 microparticles or nanoparticles synthesized by solid-state or sol-gel methods, respectively. First, electrochemical testing showed that electrodes made of Ti 2 Nb 2 O 9 nanoparticles exhibited larger specific capacity, smaller polarization, and better capacity retention at large currents than those made of Ti 2 Nb 2 O 9 microparticles. Furthermore, potentiometric entropy measurements revealed that electrodes made of either Ti 2 Nb 2 O 9 microparticles or nanoparticles showed similar thermodynamics behavior governed by lithium intercalation in solid solution, as confirmed by in situ XRD measurements. However, electrodes made of Ti 2 Nb 2 O 9 nanoparticles featured smaller overpotential and faster lithium ion transport than those made of Ti 2 Nb 2 O 9 microparticles. In fact, operando isothermal calorimetry revealed smaller instantaneous and time-averaged irreversible heat generation rates at electrodes made of Ti 2 Nb 2 O 9 nanoparticles, highlighting their smaller resistive losses and larger electrical conductivity. Finally, the measured total heat generation over a charging/discharging cycle matched the measured net electrical energy loss. Overall, Ti 2 Nb 2 O 9 nanoparticles synthesized by the novel sol-gel method displayed excellent cycling performance and reduced heat generation as a fast-charging lithium-ion battery anode material. These features present major advantages for actual battery systems including larger energy and power densities, simpler thermal management, and enhanced safety.

25 ENERGY STORAGE↗

Amorphization of Pseudocapacitive T−Nb 2 O 5 Accelerates Lithium Diffusivity as Revealed Using Tunable Isomorphic Architectures

Abstract Intercalation pseudocapacitance can combine capacitor‐like power densities with battery‐like energy densities. Such surface‐limited behavior requires rapid diffusion where amorphization can increase solid‐state diffusivity. Here intercalation pseudocapacitive materials with tailored extents of amorphization in T‐Nb 2 O 5 are first reported. Amorphization was characterized with WAXS, XPS, XAFS, and EPR which suggested a peroxide‐rich (O 2 2− ) surface that was consistent with DFT predictions. A series of tunable isomorphic architectures enabled comparisons while independently varying transport parameters. Through process of elimination, solid‐state lithium diffusion was identified as the dominant diffusive‐constraint dictating the maximum voltage sweep rate for surface‐limited kinetics ( v SLT ), termed the Surface‐Limited Threshold (SLT). The v SLT increased with amorphization however stable cycling required crystalline T‐Nb 2 O 5 . A current‐response model using series‐impedances well‐matched these observations. This perspective revealed that amorphization of T‐Nb 2 O 5 enhanced solid‐state diffusion by 12.2 % and increased surface‐limitations by 17.0 % (stable samples). This approach enabled retaining 95 % lithiation capacity at ∼800 mV s −1 (1,600 C‐rate equivalent).

25 ENERGY STORAGE↗

NASA Tech Briefs, June 2003

Topics covered include: Nulling Infrared Radiometer for Measuring Temperature; The Ames Power Monitoring System; Hot Films on Ceramic Substrates for Measuring Skin Friction; Probe Without Moving Parts Measures Flow Angle; Detecting Conductive Liquid Leaking from Nonconductive Pipe; Adaptive Suppression of Noise in Voice Communications; High-Performance Solid-State W-Band Power Amplifiers; Microbatteries for Combinatorial Studies of Conventional Lithium-Ion Batteries; Correcting for Beam Aberrations in a Beam-Waveguide Antenna; Advanced Rainbow Solar Photovoltaic Arrays; Metal Side Reflectors for Trapping Light in QWIPs; Software for Collaborative Engineering of Launch Rockets; Software Assists in Extensive Environmental Auditing; Software Supports Distributed Operations via the Internet; Software Estimates Costs of Testing Rocket Engines; yourSky: Custom Sky-Image Mosaics via the Internet; Software for Managing Inventory of Flight Hardware; Lower-Conductivity Thermal-Barrier Coatings; Process for Smoothing an Si Substrate after Etching of SiO2; Flexible Composite-Material Pressure Vessel; Treatment to Destroy Chlorohydrocarbon Liquids in the Ground; Noncircular Cross Sections Could Enhance Mixing in Sprays; Small, Untethered, Mobile Roots for Inspecting Gas Pipes; Paint-Overspray Catcher; Preparation of Regular Specimens for Atom Probes; Inverse Tomo-Lithography for Making Microscopic 3D Parts; Predicting and Preventing Incipient Flameout in Combustors; MEMS-Based Piezoelectric/Electrostatic Inchworm Actuator; Metallized Capillaries as Probes for Raman Spectroscopy; Adaptation of Mesoscale Weather Models to Local Forecasting; Aerodynamic Design using Neural Networks; Combining Multiple Gyroscope Outputs for Increased Accuracy; and Improved Collision-Detection Method for Robotic Manipulator.

Source record↗

Optimizing Microenvironment of Asymmetric N,S-Coordinated Single-Atom Fe via Axial Fifth Coordination toward Efficient Oxygen Electroreduction

We report single-atom catalysts (SACs) are attractive candidates for oxygen reduction reaction (ORR). The catalytic performances of SACs are mainly determined by the surrounding microenvironment of single metal sites. Microenvironment engineering of SACs and understanding of the structure–activity relation-ship is critical, which remains challenging. Herein, a self-sacrificing strategy is developed to synthesize asymmetric N,S-coordinated single-atom Fe with axial fifth hydroxy (OH) coordination (Fe-N 3 S 1 OH) embedded in N,S codoped porous carbon nanospheres (Fe-N/S-C). Such unique penta-coordination microenvironment is determined by cutting-edge techonologies aiding of systematic simulations. The as-obtained Fe-;N/S-C exhibits superior catalytic ORR activity, and showcases a half-wave potential of 0.882 V surpassing the benchmark Pt/C. Moreover, theoretical calculations confirmed the axial OH in Fe-N 3 S 1 OH can optimize 3d orbitals of Fe center to strengthen O 2 adsorption and enhance O 2 activation on Fe site, thus reducing the ORR barrier and accelerating ORR dynamics. Furthermore, Fe-N/S-C containing H 2 -O 2 fuel cell performs a high peak power density of 512 mW cm -2 , and Fe-N/S-C based Zn-air batteries show the peak power density of 203 and 49 mW cm -2 in liquid and flexible all-solid-state configurations, respectively. This study offers a new platform for fundamentally understand the axial fifth coordination in asymmetrical planar single-atom metal sites for electrocatalysis.

microenvironment↗

High Throughput Solvent-free Manufacturing of Battery Electrodes

The project goal is to develop and demonstrate an advanced solvent-free lithium-ion battery electrode process through proposed Advanced Dry Electrode Process (ADEP) equipment, which is expected to exhibit a better binder fibrillization and high throughput and suitable for high performance electrode manufacturing, and commonize the anode and cathode dry processing equipment, supply chain and operation for lithium-ion battery OEMs for replacing the solvent-based slurry casting. Our proposed approach will facilitate low-cost battery production by addressing the following gaps in present dry electrode processing: • Extend the dry electrode fabrication process to lithium-ion battery anode manufacturing • Increase the active material content for anodes and cathodes • Intensify the process through improved mixing, powder rheology and surface modifications • Enable processing of next-generation electrode materials that are not stable to solvent or ambient air exposure. The project objectives include the development of anode-compatible binder and binder fibrillization promoter for low irreversible capacity loss, low electrode binder content yet higher film mechanical strength, and the optimization of solvent-free anode and cathode process for low cost (>60% electrode cost reduction), high performance (10% increase in energy density without sacrificing cycle life) and high throughput to enable next generation lithium-ion battery electrode production. Solvent-free electrode manufacturing will also enable next-generation cell designs based on prelithiated anodes or solid-state electrolytes.

25 ENERGY STORAGE↗

Evaporation-Induced Vertical Alignment Enabling Directional Ion Transport in a 2D-Nanosheet-Based Battery Electrode

2D nanosheets have been widely explored as electrode materials owing to their extraordinarily high electrochemical activity and fast solid-state diffusion. However, the scalable electrode fabrication based on this type of material usually suffers from severe performance losses due to restricted ion-transport kinetics in a large thickness. Here, a novel strategy based on evaporation-induced assembly to enable directional ion transport via forming vertically aligned nanosheets is reported. The orientational ordering is achieved by a rapid evaporation of mixed solvents during the electrode fabrication process. Compared with conventional drop-cast electrodes, which exhibit a random arrangement of the nanosheets and obvious decrease of rate performance with increasing thickness, the electrode based on the vertically aligned nanosheets is able to retain the original high rate capability even at high mass loadings and electrode thickness. Furthermore, combined electrochemical and structural characterization reveals the electrode composed of orientation-controlled nanosheets to possess lower charge-transfer resistances, leading to more complete phase transformation in the active material.

25 ENERGY STORAGE↗

Lithium superoxide encapsulated in a benzoquinone anion matrix

Lithium peroxide is the crucial storage material in lithium–air batteries. Understanding the redox properties of this salt is paramount toward improving the performance of this class of batteries. Lithium peroxide, upon exposure to p –benzoquinone (p–C 6 H 4 O 2 ) vapor, develops a deep blue color. This blue powder can be formally described as [Li 2 O 2 ] 0.3 • [LiO 2 ] 0.7 • {Li[p–C 6 H 4 O 2 ]} 0.7 , though spectroscopic characterization indicates a more nuanced structural speciation. Infrared, Raman, electron paramagnetic resonance, diffuse-reflectance ultraviolet-visible and X-ray absorption spectroscopy reveal that the lithium salt of the benzoquinone radical anion forms on the surface of the lithium peroxide, indicating the occurrence of electron and lithium ion transfer in the solid state. As a result, obligate lithium superoxide is formed and encapsulated in a shell of Li[p–C 6 H 4 O 2 ] with a core of Li 2 O 2 . Lithium superoxide has been proposed as a critical intermediate in the charge/discharge cycle of Li–air batteries, but has yet to be isolated, owing to instability. The results reported herein provide a snapshot of lithium peroxide/superoxide chemistry in the solid state with redox mediation.

25 ENERGY STORAGE↗

Probing the electrolyte/electrode interface with vibrational sum frequency generation spectroscopy: A review

Over the past decades, Lithium-ion batteries have seen extensive improvements, and as a result are now the primary choice in many applications for their power, energy, and durability. In recent years, battery cost has reduced by orders of magnitude through adoption of new materials and processes. Despite these advances, interfaces in these battery systems are yet to be fully understood. This is seen as a major limitation to further increase cycle life, calendar life, abuse tolerance, and performances. A major obstacle is a lack of comprehensive understanding of the complex dynamic chemical processes occurring at the electrolyte/electrode interface. In this context, vibrational sum frequency generation (vSFG) spectroscopy possesses the unique capability of probing a molecularly thin interfacial layer to obtain molecular-level information through nonlinear optical interaction. Probing the molecular level processes at the interfaces using such a versatile technique would be a game changer in the advancement of current battery research knowledge. This review article summarizes recent vSFG studies on the electrolyte/electrode interface of various electrode materials and nonaqueous electrolytes for LIBs and discusses future research perspectives. Finally, overall, this focused review highlights the advantages and versatility of vSFG that can be used to further advance present-day battery research.

25 ENERGY STORAGE↗

Phase evolution and structural modulation during in situ lithiation of MoS 2 , WS 2 and graphite in TEM

Li-ion batteries function by Li intercalating into and through the layered electrode materials. Intercalation is a solid-state interaction resulting in the formation of new phases. The new observations presented here reveal that at the nanoscale the intercalation mechanism is fundamentally different from the existing models and is actually driven by nonuniform phase distributions rather than the localized Li concentration: the lithiation process is a ‘distribution-dependent’ phenomena. Direct structure imaging of 2H and 1T dual-phase microstructures in lithiated MoS 2 and WS 2 along with the localized chemical segregation has been demonstrated in the current study. Li, a perennial challenge for the TEM, is detected and imaged using a low-dose, direct-electron detection camera on an aberration-corrected TEM and confirmed by image simulation. This study shows the presence of fully lithiated nanoscale domains of 2D host matrix in the vicinity of Li-lean regions. This confirms the nanoscale phase formation followed by Oswald ripening, where the less-stable smaller domains dissolves at the expense of the larger and more stable phases.

25 ENERGY STORAGE↗

Garnet/PVDF-HFP Hybrid Membranes for Li-Metal Batteries: Cooperative Research and Development Final Report, CRADA Number CRD-19-00807

Hazen Research, Inc., in collaboration with University of Colorado, Boulder (CU-B) and National Renewable Energy Laboratory (NREL), will develop and demonstrate a ceramic-polymer hybrid membrane based on garnet (Li7La3Zr2O12) and PVDF (Poly Vinylidene Fluoride)-HFP (Hexafluoropropylene) adaptable to Li-metal anodes. Under this CRADA, NREL will test the developed membranes providing feedback and advice to demonstrate hybrid membranes with Li-ion conductivity >10-4 S/cm at room temperature that are stable with Li-metal, followed by demonstration of full cells with Li-metal anode.

33 ADVANCED PROPULSION SYSTEMS↗

Nondestructive flash cathode recycling

Effective recycling of end-of-life Li-ion batteries (LIBs) is essential due to continuous accumulation of battery waste and gradual depletion of battery metal resources. The present closed-loop solutions include destructive conversion to metal compounds, by destroying the entire three-dimensional morphology of the cathode through continuous thermal treatment or harsh wet extraction methods, and direct regeneration by lithium replenishment. Here, we report a solvent- and water-free flash Joule heating (FJH) method combined with magnetic separation to restore fresh cathodes from waste cathodes, followed by solid-state relithiation. The entire process is called flash recycling. This FJH method exhibits the merits of milliseconds of duration and high battery metal recovery yields of ~98%. After FJH, the cathodes reveal intact core structures with hierarchical features, implying the feasibility of their reconstituting into new cathodes. Relithiated cathodes are further used in LIBs, and show good electrochemical performance, comparable to new commercial counterparts. Life-cycle-analysis highlights that flash recycling has higher environmental and economic benefits over traditional destructive recycling processes.

25 ENERGY STORAGE↗

Transferring Liquid Metal to form a Hybrid Solid Electrolyte via a Wettability-Tuning Technology for Lithium-Metal Anodes

Integrating solid-state electrolyte (SSE) into Li-metal anodes has demonstrated great promise to unleash the high energy density of rechargeable Li-metal batteries. However, fabricating a highly cyclable SSE/Li-metal anode remains a major challenge because the densification of the SSE is usually incompatible with the reactive Li metal. Here, a liquid-metal-derived hybrid solid electrolyte (HSE) is proposed, and a facile transfer technology to construct an artificial HSE on the Li metal is reported. By tuning the wettability of the transfer substrates, electron- and ion-conductive liquid metal is sandwiched between electron-insulating and ion-conductive LiF and oxides to form the HSE. The transfer technology renders the HSE continuous, dense, and uniform. The HSE, having high ion transport, electron shut-off, and mechanical strength, makes the composite anode deliver excellent cyclability for over 4000 h at 0.5 mA cm(-2) and 1 mAh cm(-2) in a symmetrical cell. When pairing with LiFePO4 and sulfur cathodes, the HSE-coated Li metal dramatically enhances the performance of full cells. Therefore, this work demonstrates that tuning the interfacial wetting properties provides an alternate approach to build a robust solid electrolyte, which enables highly efficient Li-metal anodes.

li-metal anodes↗

A Materials Perspective on Direct Recycling of Lithium-Ion Batteries: Principles, Challenges and Opportunities

As the dominant means of energy storage technology today, the widespread deployment of lithium-ion batteries (LIBs) would inevitably generate countless spent batteries at their end of life. From the perspectives of environmental protection and resource sustainability, recycling is a necessary strategy to manage end-of-life LIBs. Compared with traditional hydrometallurgical and pyrometallurgical recycling methods, the emerging direct recycling technology, rejuvenating spent electrode materials via a non-destructive way, has attracted rising attention due to its energy efficient processes along with increased economic return and reduced CO 2 footprint. This review investigates the state-of-the-art direct recycling technologies based on effective relithiation through solid-state, aqueous, eutectic solution and ionic liquid mediums and thoroughly discusses the underlying regeneration mechanism of each method regarding different battery chemistries. It is concluded that direct regeneration can be a more energy-efficient, cost-effective, and sustainable way to recycle spent LIBs compared with traditional approaches. Additionally, it is also identified that the direct recycling technology is still in its infancy with several fundamental and technological hurdles such as efficient separation, binder removal and electrolyte recovery. Finally, in addressing these remaining challenges, this review proposes an outlook on potential technical avenues to accelerate the development of direct recycling toward industrial applications.

25 ENERGY STORAGE↗

Molten Salt Electrolytes: Computational Analysis of Transport, Electrochemical Properties and Designing New Mixtures

Electric aircraft propulsion has gained a traction over the last decade due to possible high-energy density electrochemistries with reasonable cycle life and identification of non-flammable chemistries that can guarantee much better safety. Commercial Li-ion batteries cannot reach such high capacities because of weight limitations that arise from the widely used intercalation electrodes. Also, use of organic electrolytes make them highly susceptible to fire on exposure to air and humidity. Currently, use of Lithium metal anode along with conversion electrochemistries such as Li-O2 and Li-S are being pursued to achieve such high energy densities. Safer inorganic solid-state electrolytes, recently discovered Water-in-Salt electrolytes, molten salt electrolytes are some of the alternatives being pursued for a safer/non-flammable battery. Of these safer alternatives, molten-salt electrolytes offer some attractive properties: liquid at operating temperatures resulting in better electrode-wetting, stable interface with Li-metal anodes and good ionic conductivity; their only drawback being high operating temperatures. In this talk, we will discuss some of the computational studies, driven via atomistic simulations, of the properties of molten-salt electrolytes including transport mechanism and interface stability. We will also discuss predicting electrochemical properties of these high-temperature electrolytes. Further, we will discuss a thermodynamic approach to predicting new molten-salt eutectics with lower melting points.

Molten Salt Electrolytes↗

Operando NMR characterization of cycled and calendar aged nanoparticulate silicon anodes for Li-ion batteries

Replacing graphite anodes with Si anodes can greatly increase the energy of current Li-ion batteries. Detailed characterization of Si lithiation reactions, SEI formation, and reversibility are therefore active areas of research. Solid-state 7 Li nuclear magnetic resonance (NMR) spectroscopy is useful for characterizing different lithium local environments within Si anodes. Here, we developed an operando NMR methodology to characterize aging of carbon-coated nanoparticulate Si anodes in pouch cells paired with Ni-rich cathodes. We observed a new lithiation mechanism in the Si nanoparticles: direct formation of over-lithiated Li 15+x Si 4 (x<0.6) phase. Furthermore, our novel operando cells maintained good performance with long-term cycle and calendar aging. Here we identified trapped lithium silicides as a major contributor to capacity fade with aging. Finally, we determined that the addition of Mg (TFSI) 2 to the electrolyte decreased the amount of trapped lithium silicides and therefore increased the capacity and capacity retention for the nanoparticulate Si used.

25 ENERGY STORAGE↗