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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7

Probabilistic machine learning for battery health diagnostics and prognostics—review and perspectives

Abstract Diagnosing lithium-ion battery health and predicting future degradation is essential for driving design improvements in the laboratory and ensuring safe and reliable operation over a product’s expected lifetime. However, accurate battery health diagnostics and prognostics is challenging due to the unavoidable influence of cell-to-cell manufacturing variability and time-varying operating circumstances experienced in the field. Machine learning approaches informed by simulation, experiment, and field data show enormous promise to predict the evolution of battery health with use; however, until recently, the research community has focused on deterministic modeling methods, largely ignoring the cell-to-cell performance and aging variability inherent to all batteries. To truly make informed decisions regarding battery design in the lab or control strategies for the field, it is critical to characterize the uncertainty in a model’s predictions. After providing an overview of lithium-ion battery degradation, this paper reviews the current state-of-the-art probabilistic machine learning models for health diagnostics and prognostics. Details of the various methods, their advantages, and limitations are discussed in detail with a primary focus on probabilistic machine learning and uncertainty quantification. Last, future trends and opportunities for research and development are discussed.

25 ENERGY STORAGE↗

Performance of the IUE Spacecraft Batteries After 70 Months

The battery performance of the IUE spacecraft launched in 1977 is updated. Changes made in the battery operational procedures are detailed. The aging effects after several eclipse seasons and the effects of 8 C temperature was anticipated. The batteries met their design goals and should meet the 10 year goal.

Tiller, S. E.↗

Stoichiometric irreversibility of aged garnet electrolytes

Solid-state lithium batteries (SSLBs) have been regarded as one of the next-generation energy storage systems. With the adoption of solid-state electrolytes (SSEs) and lithium metal anodes, SSLBs enable higher energy density and more reliable safety than the state-of-the-art lithium-ion batteries. Among potential SSEs, the cation-doped Li 7 La 3 Zr 2 O 12 (LLZO) is promising for its high ionic conductivity (~10 –3 S cm –2 ) at room temperature and high stability with Li metal anode. However, the storage of doped LLZO in the ambient condition suffers the aging effect, including the structural transition (i.e. low-temperature cubic form) and the stoichiometric changes (i.e. Li 2 CO 3 ). These changes are detrimental to LLZO ionic conductivity and interfacial stability in SSLBs. To this end, in this study we are motivated to investigate the structural and stoichiometric reversibility of aged LLZO during thermal treatment. With the help of an in-situ synchrotron-based high-energy X-ray diffraction technique, our experiments revealed that the LLZO powders became a low-temperature cubic phase when exposed to the ambient condition for an extended period of time. A high temperature cubic form can be restored after a thermal treatment of the aged LLZO powder, regardless of the type of dopant. However, the restoration of the stoichiometry remained a challenge, and the degree of the restoration showed a clear dependence on the dopant chemistry.

36 MATERIALS SCIENCE↗

A Surface Se-Substituted LiCo[O 2-δ Se δ ] Cathode with Ultrastable High-Voltage Cycling in Pouch Full-Cells

Cycling LiCoO 2 to above 4.5 V for higher capacity is enticing; however, hybrid O anion- and Co cation-redox (HACR) at high voltages facilitates intrinsic O α - (α < 2) migration, causing oxygen loss, phase collapse, and electrolyte decomposition that severely degrade the battery cyclability. Hereby, commercial LiCoO 2 particles are operando treated with selenium, a well-known anti-aging element to capture oxygen-radicals in the human body, showing an “anti-aging” effect in high-voltage battery cycling and successfully stopping the escape of oxygen from LiCoO 2 even when the cathode is cycled to 4.62 V. Furthermore, ab initio calculation and soft X-ray absorption spectroscopy analysis suggest that during deep charging, the precoated Se will initially substitute some mobile O α - at the charged LiCoO 2 surface, transplanting the pumped charges from O α - and reducing it back to O 2- to stabilize the oxygen lattice in prolonged cycling. As a result, the material retains 80% and 77% of its capacity after 450 and 550 cycles under 100 mA g -1 in 4.57 V pouch full-cells matched with a graphite anode and an ultralean electrolyte (2 g Ah -1 ).

36 MATERIALS SCIENCE↗

Corrosion of lithium metal anodes during calendar ageing and its microscopic origins

Rechargeable lithium (Li) metal batteries must have long cycle life and calendar life (retention of capacity during storage at open circuit). Particular emphasis has been placed on prolonging the cycle life of Li metal anodes, but calendar ageing is less understood. Here, we show that Li metal loses at least 2–3% of its capacity after only 24 hours of ageing, regardless of the electrolyte chemistry. These losses of capacity during calendar ageing also shorten the cycle life of Li metal batteries. Cryogenic transmission electron microscopy shows that chemical corrosion of Li and the continuous growth of the solid electrolyte interphase—a passivation film on Li—cause the loss of capacity. Electrolytes with long cycle life do not necessarily form a solid electrolyte interphase with more resistance to chemical corrosion, so functional electrolytes must simultaneously minimize the rate of solid electrolyte interphase growth and the surface area of electrodeposited Li metal.

36 MATERIALS SCIENCE↗

Life Extension Activities for the Hubble Space Telescope

With the cancellation of the Hubble Space Telescope (HST) Servicing Mission 4 (SM4), the HST Project will face numerous challenges to keep the Telescope operating during the remainder of the decade. As part of the SM4, the HST Project had planned to install various upgrades to the Telescope including the installation of new batteries and new rate integrating gyros. Without these upgrades, reliability analysis indicates that the spacecraft will lose the capability to conduct science operations later this decade. The HST team will be severely challenged to maximize the Telescope's remaining operational lifetime, while still trying to maximize - its science output and quality. Two of the biggest areas of concern are the age and condition of the batteries and gyros. Together they offer the largest potential extension in Telescope lifetime and present the biggest challenges to the HST team. The six Ni-H batteries on HST are the original batteries from launch. With fourteen years of operational life, these batteries have collectively lasted longer than any other comparable mission. Yet as with all batteries, their capacity has been declining. Engineers are examining various methods to prolong the life of these mission critical batteries, and retard the rate of degradation. This paper will focus on these and other efforts to prolong the life of the HST, thus enabling it to remain a world-class observatory for as long as possible.

Walyus, Keith D.↗

Study on the Carbon Nanostructures for Nanosized Si Electrodes

Silicon (Si) has been considered as a next-generation anode material due to natural abundance, low operating potential (<0.5 V vs. Li/Li+), and high theoretical specific capacity of 4200 mAh g-1.[1] However, the electrochemical alloying reaction of Si involves large volume changes of 400% during lithiation and delithiation, causing cracking and pulverization of Si.[1] In addition, solid electrolyte interface (SEI) of Si anode experiences constant changes due to unstable SEI reactivity.[2] Considerable efforts have been made to design nanostructured Si materials to address the issues because nanostructuring can relieve the mechanical strain.[3] However, when compared to micrometer-sized active materials having sufficient electrolyte pathway through interparticle space, the nanoparticle (NP)-based electrodes tend to be densely packed. As mass loading is higher and electrode is thicker, ion transport issue can become more severe in the densely packed electrodes.[4] In this work, we will present studies on engineered porosity impacts performance in Si NP electrodes by altering carbon nanostructures. We explore the extreme limit of effectively non-porous electrodes using quasi-spherical, Si NPs, which result in densely packed electrodes when slurry is prepared with conventional carbon black. We engineer porosity using carbon nanostructures including multi-walled carbon nanotubes and carbon nanorods in place of conventional carbon black to create pore structure in Si NP-based electrodes. These experiments provide a correlation between mass loading, porosity and silicon utilization in Si NP-based electrodes. References: [1] C. K. Chan, H. Peng, G. Liu, K. Mcllwrath, X. F. Zhang, R. A. Huggins, Y. Cui, "High-performance lithium battery anodes using silicon nanowires", Nat. Nanotechnol., 2008, 3, 31, [2] J. D. McBrayer, M.-T. F. Rodrigues, M. C. Schulze, D. P. Abraham, C. A. Apblett, I. Bloom, G. M. Carroll, A. M. Coclasure, C. Fang, K. L. Harrison, G. Liu, S. D. Minteer, N. R. Neale, G. M. Veith, C. S. Johnson, J. T. Vaughey, A. K. Burrel, B. Cunningham, "Calendar aging of silicon-containing batteries", Nat. Energy, 2021, 6, 1164, [3] H. Wu, G. Zheng, N. Liu, T. J. Carney, Y. Yang, Y. Cui, "Engineering Empty space between Si Nanoparticles for Lithium-Ion Battery Anodes", Nano Lett., 2012, 12, 904, [4] X. Zhang, Z. Ju, Y. Zhu, K. J. Takeuchi, E. S. Takeuchi, A. C. Marschilok, G. Yu, "Multiscale Understanding and Architecture Design of High Energy/Power Lithium-Ion Battery Electrodes", Adv. Energy Mater., 2021, 11, 2000808

carbon nanostructure↗

Critical Contribution of Imbalanced Charge Loss to Performance Deterioration of Si-Based Lithium-Ion Cells during Calendar Aging

Increasing the energy density of lithium-ion batteries, and thereby reducing costs, is a major target for industry and academic research. One of the best opportunities is to replace the traditional graphite anode with a high-capacity anode material, such as silicon. However, Si-based lithium-ion batteries have been widely reported to suffer from a limited calendar life for automobile applications. Heretofore, there lacks a fundamental understanding of calendar aging for rationally developing mitigation strategies. Both open-circuit voltage and voltage-hold aging protocols were utilized to characterize the aging behavior of Si-based cells. Particularly, a high-precision leakage current measurement was applied to quantitatively measure the rate of parasitic reactions at the electrode/electrolyte interface. The rate of parasitic reactions at the Si anode was found 5 times and 15 times faster than those of LiNi 0.8 Mn 0.1 Co 0.1 O 2 and LiFePO 4 cathodes, respectively. Here, the imbalanced charge loss from parasitic reactions plays a critical role in exacerbating performance deterioration. In addition, a linear relationship between capacity loss and charge consumption from parasitic reactions provides fundamental support to assess calendar life through voltage-hold tests. These new findings imply that longer calendar life can be achieved by suppressing parasitic reactions at the Si anode to balance charge consumption during calendar aging.

25 ENERGY STORAGE↗

The Importance of a Moving Boundary Approach for Modeling the SEI Layer Growth to Predict Capacity Fade

One of the contributing factors to the aging of lithium-ion batteries is the growth of the solid-electrolyte interphase (SEI) layer. The growth of the SEI layer leads to the irreversible loss of lithium available for cycling and increases the resistance of the battery. Physics-based models in literature model the kinetically limited or solvent diffusion-limited growth. In such models, the interface resistance is a constant, and the contribution to the overpotential of the intercalation reaction from the SEI layer is considered to be ohmic. In this study, we propose a model that describes the growth of the SEI layer on the electrode surface as a moving interface. The transport of lithium ions and the solvent in the electrolyte are affected by this moving interface. The equations that govern the species transport and the potential drop across the SEI layer are derived from dilute solution theory and solved by transforming the coordinates of the moving boundary. The ion transport induces changes in the conductivity across the SEI layer, which affects the potential drop that arises due to its growth. The effects of this potential on capacity fade are studied over cycling the battery.

25 ENERGY STORAGE↗

Hybrid Power Management

An engineering discipline denoted as hybrid power management (HPM) has emerged from continuing efforts to increase energy efficiency and reliability of hybrid power systems. HPM is oriented toward integration of diverse electric energy-generating, energy-storing, and energy-consuming devices in optimal configurations for both terrestrial and outer-space applications. The basic concepts of HPM are potentially applicable at power levels ranging from nanowatts to megawatts. Potential applications include terrestrial power-generation, terrestrial transportation, biotechnology, and outer-space power systems. Instances of this discipline at prior stages of development were reported (though not explicitly labeled as HPM) in three prior NASA Tech Briefs articles: "Ultracapacitors Store Energy in a Hybrid Electric Vehicle"(LEW-16876), Vol. 24, No. 4 (April 2000), page 63; "Photovoltaic Power Station With Ultracapacitors for Storage" (LEW-17177), Vol. 27, No. 8 (August 2003), page 38; and "Flasher Powered by Photovoltaic Cells and Ultracapacitors" (LEW-17246), Vol. 24, No. 10 (October 2003), page 37. As the titles of the cited articles indicate, the use of ultracapacitors as energy-storage devices lies at the heart of HPM. An ultracapacitor is an electrochemical energy-storage device, but unlike in a conventional rechargeable electrochemical cell or battery, chemical reactions do not take place during operation. Instead, energy is stored electrostatically at an electrode/electrolyte interface. The capacitance per unit volume of an ultracapacitor is much greater than that of a conventional capacitor because its electrodes have much greater surface area per unit volume and the separation between the electrodes is much smaller. Power-control circuits for ultracapacitors can be simpler than those for batteries, for two reasons: (1) Because of the absence of chemical reactions, charge and discharge currents can be greater than those in batteries, limited only by the electrical resistances of conductors; and (2) whereas the charge level of a battery depends on voltage, temperature, age, and load condition, the charge level of an ultracapacitor, like that of a conventional capacitor, depends only on voltage.

Eichenberg, Dennis↗

Effects of catholyte aging on high-nickel NMC cathodes in sulfide all-solid-state batteries

Sulfide solid-state electrolytes (SSEs) in all-solid-state batteries (SSBs) are recognized for their high ionic conductivity and inherent safety. The LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cathode offers a high thermodynamic potential of approximately 3.8 V vs. Li/Li + and a theoretical specific capacity of 200 mA h g −1 . However, the practical utilization of NMC811 in sulfide SSBs faces significant interfacial challenges. The oxidation instability of sulfide solid electrolytes against NMC811 and the formation of the cathode electrolyte interphase (CEI) during cycling lead to degradation and reduced cell performance. Volumetric changes in NMC during lithiation and de-lithiation can also cause detachment from sulfide electrolytes or internal particle cracking. Despite extensive galvanostatic cycling studies to address the issues, the calendar life of sulfide SSBs remains poorly understood. Here, we systematically studied the effects of four different catholytes on the calendar aging of LiNbO 3 (LNO)-coated NMC811, including Li 6 PS 5 Cl (LPSCl), Li 3 InCl 6 –Li 6 PS 5 Cl (LIC–LPSCl), Li 3 YCl 6 –Li 6 PS 5 Cl (LYC–LPSCl), and Li 10 GeP 2 S 12 (LGPS). Our results indicate that LPSCl provides optimal capacity retention when stored at high state-of-charge (SOC) at room temperature, but the LIC–LPSCl cathode shows significant capacity degradation and chemical incompatibility. We also established an effective electrochemical calendar aging testing protocol to simulate daily usage, enabling quick inference of the calendar life of SSBs. In conclusion, this new testing approach accelerates materials selection strategies for high-nickel NMC composite cathodes in sulfide SSBs.

25 ENERGY STORAGE↗

Optimization of Energy Storage System Economics and Controls by Incorporating Battery Degradation Costs in REopt

The use of stationary electrochemical energy storage systems utilizing lithium-ion batteries has increased rapidly as the production scale and price for lithium-ion batteries has decreased. These energy storage systems are crucial for maintaining grid resiliency, especially for grids operating with high penetration of renewable energy generation assets or for with a variety of distributed energy generation and storage systems. One challenging factor for the development of battery energy storage systems is estimating the proper sizing, in terms of both power and energy, that minimizes total costs over the lifetime of the systems; this calculation is difficult in simple cases, where a battery is costed independently, but is extremely challenging when building loads and electrical generation by photovoltaic resources are also considered. REopt is a techoeconomic optimization tool developed by NREL to address these challenges. Previously, battery degradation has been priced by simply assuming a 10-year replacement schedule for battery systems. However, this does not account for varying degradation trends observed across real-world batteries, or allow for batteries to be operated in a degradation-aware manner that optimizes battery dispatch based on operating costs. This work incorporates a battery life model into REopt. This battery life model is simple, so that it may be solvable within the constrains of a mixed-integer linear optimization problem, but is fit to accelerated aging data recorded in the lab. To achieve the best possible accuracy for lifetime estimates given these constraints, parameters for the battery life model in REopt are estimated by fitting 20-year simulations of battery life after identifying state-space battery degradation model from accelerated aging data. Comparisons of battery life predicted in REopt and from the state-space battery degradation model to ensure validity of lifetime estimates made by REopt. Battery life and cost is optimized by controlling three decision to minimize system life cost: battery sizing, daily state-of-charge, and daily energy-throughput. The cost of battery degradation as a function of these control variables is then estimated assuming two possible maintenance strategies: replacement, where the entire battery system is replaced if cell reach an end-of-life capacity threshold; and augmentation, which establishes a fund to pay for continual purchase of new batteries to maintain the initial energy capacity of the system. These two strategies offer conservative (for replacement) and optimistic (for augmentation) bounds for total system cost. The degradation cost incurred by these strategies is then used to control battery dispatch decisions, operating the battery in a degradation-aware manner that maximizes battery lifetime while also providing energy when favorable. Because the mixed-integer linear program has perfect foresight of future energy needs, batteries with degradation costs are always operated using 'just-in-time' charging, which is unrealistic, as no energy is left in the storage system to perform other energy services or to serve as emergency back-up power. To combat this, an inequality constraint on the average annual state-of-charge is imposed, and the sensitivity of system cost to average stored energy, e.g., the cost of system resiliency, can be quantified. Analysis of results has several conclusions, for instance, oversizing of battery storage systems is not a cost burden when battery storage is an optimal solution, as any additional battery capacity can simply be utilized to avoid costs of purchasing energy from a utility.

battery↗

Quantifying the Reactivity of Isolated Li x Si Domains in Si Anodes Using Operando NMR

The use of Si anodes can greatly improve the energy density of Li-ion batteries. However, understanding and mitigation of calendar aging remains a barrier to commercialization. Here, in this short report, we utilize operando Nuclear Magnetic Resonance (NMR) spectroscopy to detect and quantify lithium silicides (Li x Si) as they form and react within Si anodes in pouch cells during calendar aging. We provide direct experimental evidence of complex aging phenomena in the Si anodes, including both SEI growth and dissolution during storage. Formation of electrochemically isolated Li x Si is also observed, as indicated by the partial persistence of highly lithiated phases after the cell is discharged. Remarkably, we show that these isolated domains can themselves self-discharge over time, suggesting that their detection can be challenging in post-mortem studies. Finally, we show that aging outcomes depend heavily on the type of silicon particles contained within the electrode, and that certain surface coatings can help decrease the reactivity between lithium silicides and the electrolyte.

Li-ion battery↗

The Economic Impact of Battery Degradation Modelling Uncertainty

Battery energy storage systems (BESS) are used for a variety of applications, with their economic benefit often being the decisive factor for deployment. A multitude of physico-chemical aging mechanisms lead to capacity fade over a BESS life cycle. The models that are used to describe this capacity fade are prone to inherent model errors. Through a holistic techno-economic modelling approach, we investigate the impact of battery degradation modelling uncertainty on the economic benefit of representative BESS applications. Here, it is shown how improved parameter fit quality can reduce the resulting economic uncertainty. Furthermore, we highlight that the consideration of degradation modelling uncertainty is especially crucial when: (i) the cash flow highly depends on the available battery capacity, (ii) a fixed, e.g. warranty mandated, state of health limit acts as the threshold for battery end-of-life, (iii) long evaluation periods and low discount rates are the focus of economic evaluation.

aging↗

On the dynamics of the fluoroethylene carbonate generated solid electrolyte interphase on silicon anodes during calendar life aging

Here, the widespread use of silicon (Si)-rich anodes in lithium-ion batteries (LIBs) is impeded by an unstable solid electrolyte interphase (SEI) incurring insufficient cell life. Fluoroethylene carbonate (FEC) additive in the electrolyte significantly improves cycle life. However, the gains on calendar life remain unclear; the SEI structure still undergoes detrimental alterations at rest. Thus, elucidating the SEI dynamics during calendar aging is critical to mitigating time-dependent capacity degradation. ATR-FTIR, XPS, and ToF-SIMS are used herein to investigate the SEI structure before and after calendar aging. Si cycled without FEC exhibits no notable SEI chemistry changes Pre- and Post-aging, leaving poor passivation as the main failure pathway. Conversely, the FEC-SEI starts as short oligomeric species from FEC/EC electroreduction prior to aging; after calendar aging, polymerized carbonates become consistently more prominent. Unexpectedly, the deposition of self-polymerized FEC species results from time exposure to the delithiated Si specifically as opposed to the lithiated surface. This unexpected finding is supported by another recent Si calendar-aging research, which albeit not investigating FEC, finds global failure of the SEI upon delithiation resulting in ∼247 fold more reactive surface compared to the lithiated.

Batteries↗

Resolving three-dimensional nanoscale heterogeneities in lithium metal batteries with cryoelectron tomography

Current direct observation of sensitive battery materials and interfaces primarily relies on two-dimensional (2D) imaging, leaving out their three-dimensional (3D) relationship. Here, in this study, we used cryoelectron tomography (cryo-ET) to visualize the lithium metal anode in 3D at nanometer resolution and cryoelectron microscopy (cryo-EM) to reveal atomic details in local regions. We imaged both freshly prepared and calendar-aged Li metal anodes to reveal the development of LiH in Li dendrites and the Li-LiH interface, as well as the development of the solid-electrolyte interphase (SEI). Using a convolutional neural network-based technique, the 3D arrangement of Li metal, along with nanoscale LiH and Cu heterogeneities in dendrites, was visualized and annotated. In longer-term calendar aging, we observed more substantial LiH growth accompanied by extended SEI growth. Our results show that the growth of LiH and the extended SEI during battery calendar aging are temporally and spatially separate processes.

LiH↗

Fast-Charging Aging Considerations: Incorporation and Alignment of Cell Design and Material Degradation Pathways

Fast charging of batteries for electric vehicles is seen as one of the most direct ways to enhance adoption. Currently, fast charging is limited by increased cell aging, which is primarily driven by Li plating and degradation of cathode materials. Here, using combined sets of experimental and computational analysis and a suite of different charge protocols, we begin to examine the interplay between failure mode, cell designs, and ultimately aging mechanisms. Slight variation in cell design and the subsequent impacts that charge protocols have on aging can create distinct cell-to-cell variation. As little as 2% difference in porosity change at the cell negative electrode during cycling due to early Li metal plating has been found to alter the aging pathway and either accelerate or inhibit the loss due to Li plating.

25 ENERGY STORAGE↗