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DOE OSTI2024

Trace LiBF 4 Enabling Robust LiF-Rich Interphase for Durable Low-Temperature Lithium-Ion Pouch Cells

Lithium-ion batteries (LIBs) with electrolytes containing lithium tetrafluoroborate (LiBF 4 ) can achieve large capacity retention under low temperature, but the accompanying rapid capacity decay inhibits commercialization. Here, in this study, the impact of LiBF 4 as a supplemental salt to LiPF 6 is systematically investigated using low ethylene carbonate (EC)-content electrolytes, along with a low-melting-point cosolvent. It is found that rational adjustment of the amount of LiBF 4 could not only regulate the interactions of anions and solvents in Li + solvation sheaths but also tune the composition and morphology of solid electrolyte interphase (SEI). It is worth noting that electrolytes with trace amount of LiBF 4 (0.05 M) show synergetic interaction between PF 6 - and Li + and decreased interaction between EC and Li + , achieving a dense and LiF-rich SEI, which enables a 200 mAh pouch cell with less gas generation, long-lived cycling, and higher low-temperature capacity, simultaneously. This work provides new insight into utilizing trace LiBF 4 for stable interface construction of durable low-temperature LIBs.

25 ENERGY STORAGE↗
DOE OSTI2026

Unravelling fast-charging degradation in NMC/Gr pouch cells: Lithium plating and SEI properties

As fast-charging technology expands across the electric vehicle and emerging energy-storage applications, understanding its impact on battery performance and longevity is critical. In this study, 1.8 Ah LiNi 0.6 Mn 0.2 Co 0.2 O 2 /graphite pouch cells were charged at various charging rates (0.5C, 2C, 4C, and 6C) to investigate the degradation mechanisms. Our results showed that well-designed NMC/Gr pouch cells could reach over 1000 cycles with a 2C charging rate, while only reaching around 500 cycles with 4C and 6C charging rates. Fast-charging effects on NMC and graphite electrodes were obtained through a series of post-mortem characterizations, including electrochemical impedance spectroscopy (EIS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). Although higher charging rates cause pulverization of NMC secondary particles, the dominant degradation mechanism driving the fading of fast-charging-related performance lies in the graphite anode, where lithium plating and LiF-rich solid electrolyte interphase (SEI) formation result in Li inventory loss and impedance growth. The postmortem results suggest that the formation of a LiF-rich SEI, which exacerbates anode impedance and some irreversible Li + ion loss, is likely driven by the substantial decomposition of PF 6 − during fast charging, an effect often overlooked in smaller laboratory-scale studies.

Luo, Mei [Argonne National Laboratory (ANL), Argon↗
DOE OSTI2025

Role of Salt Concentration on Interphase Dynamics and Chemistry of Silicon Anodes during Electrochemical Cycling

We investigated the chemistry and structure of the solid electrolyte interphase (SEI) grown over a silicon anode as a function of the lithium salt concentration. In these experiments, in situ neutron reflectivity measurements were performed to measure the thickness and composition of the SEI formed from 1.0 and 5.5 M lithium bis(trifluoromethane)sulfonimide (LiTFSI) in standard ethylene carbonate:dimethyl carbonate electrolytes. These measurements reveal the formation of a 350+ Å thick SEI layer that is predominantly organic (∼80%) and dimensionally stable when using a 1.0 M salt solution. In contrast, increasing the salt concentration to 5.5 M resulted in an SEI that exhibited thickness changes from 100 to 375 Å and became up to 30% inorganic. In conclusion, these compositional and structural changes point to the role of salt speciation on the resulting passivation of silicon electrodes and indicate the need to form more organic-like passivation layers to promote the calendar life of silicon anodes.

Electrodes↗
DOE OSTI2025

Dimolybdenum Paddlewheel Complexes with Cation Binding Sites as Electrolyte Additives to Manipulate the Solid-Electrolyte Interphase at Lithium Metal Anodes

The use of electrolyte additives at millimolar loadings to control the surface chemistry of lithium metal anodes (LMAs) is a leading strategy to improve lithium metal batteries and promote electrosynthetic reactions. Whereas previous studies employed either inorganic or organic additives, in this study, we report the first organometallic additive, Mo 2 (mea) 4 [1, mea = 2-(2-methoxyethoxy)acetate], a dimolybdenum paddlewheel complex that is stable under Li plating conditions and features cation binding sites in the second coordination sphere that promote reversible Li + coordination. Binding of Li + ions to 1 induces immobilization of cationically charged aggregates (or products thereof) into the solid electrolyte interphase (SEI), imparting multiple beneficial functions. The modified SEI was found to protect the LMA against parasitic side reactions, produce modest but measurable improvements to Li plating properties (e.g., overpotential, surface structure, and Coulombic efficiency), and improve interfacial charge transport properties. Furthermore, the most notable benefit to battery cycling performance appears in calendar aging tests, which show that the presence of the additive protects the LMA from parasitic side reactions that would otherwise decrease overall cell cycling efficiency over time. Collectively, these data disclose a tactic for designing electrolyte additives using principles of organometallic synthesis.

Additives↗
DOE OSTI2025

Enhanced Reversibility of Iron Metal Anode with a Solid Electrolyte Interphase in Concentrated Chloride Electrolytes

Iron is a promising candidate for a cost-effective anode for large-scale energy storage systems due to its natural abundance and well-established mass production. Recently, Fe-ion batteries (FeIBs) that use ferrous ions as the charge carrier have emerged as a potential storage solution. The electrolytes in FeIBs are necessarily acidic to render the ferrous ions more anodically stable, allowing a wide operation voltage window. However, the iron anode suffers severe hydrogen evolution reaction with a low Coulombic efficiency (CE) in an acidic environment, shortening the battery cycle life. Herein, a hybrid aqueous electrolyte that forms a solid-electrolyte interphase (SEI) layer on the Fe anode surface is introduced. The electrolyte mainly comprises FeCl 2 and ZnCl 2 as cosalts, where the Zn-Cl anionic complex species of the concentrated ZnCl 2 allows dimethyl carbonate (DMC) to be miscible with the aqueous ferrous electrolyte. SEI derived from DMC's decomposition passivates the iron surface, which leads to an average CE of 98.3% and much-improved cycling stability. As a result, this advancement shows the promise of efficient and durable FeIBs.

25 ENERGY STORAGE↗
DOE OSTI2025

Fine‐Tuning Li‐Ion Solvation Structure by Enhanced Solvent‐Diluent Interactions for Long‐Cycling Lithium Metal Batteries

Achieving durable lithium (Li) metal anodes in liquid electrolytes remains challenging, primarily due to the instability of the formed solid-electrolyte interphases (SEIs). Modulating the Li-ion solvation structures is pivotal in forming a stable SEI for stabilizing Li metal anodes. Here a strategy is developed to fine-tune the Li-ion solvation structures through enhanced dipole–dipole interactions between the Li-ion-coordinated solvent and the non-Li-ion-coordinating diluent, for creating a stable SEI in the developed binary salt electrolyte. The enhanced dipole–dipole interactions weaken the coordination between Li-ions and the solvents while strengthening the interaction between Li-ions and dual anions, thereby facilitating the Li-ion transport and a robust anion-derived SEI with a distinct bilayer structure. Consequently, the developed electrolyte exhibited exceptional electrochemical performance in high energy-density Li||LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cells, with long calendar life, stable cyclability at 1 C, and reliable operation between 25 and −20 °C, and it also demonstrat remarkable cycling stability for a Li||NMC811 pouch cell with projected energy density of 402 Wh kg −1 , maintaining 80% capacity retention over 606 cycles under practical conditions.

25 ENERGY STORAGE↗
DOE OSTI2026

Long cycle and calendar life of Si-based Li-ion batteries enabled by localized high-concentration electrolytes and their surprising water tolerance

Silicon-based anodes promise an increase in energy density for Li-ion batteries, yet they suffer from a poor calendar life. Researchers have posited that fluorinated lithium salt forms reactive side products that destroy the solid electrolyte interphase (SEI), even without cycling. HF is one such reactive side product formed from trace water contamination in the electrolyte. Some electrolytes, such as localized high concentration electrolytes (LHCEs) may improve cell stability in highly reactive systems, such as Li metal and Si. In the present study, LHCEs containing 200-300 ppm of water retained up to 8% greater capacity (1200-1300 mAh/g Si) in calendar life tests over 200 days compared to dried electrolytes (< 20 ppm water). Calendar aging took place at 100% state of charge. Cells with 200-300 ppm water performed comparably to cells with 20 ppm water in cycle life tests (900-1000 mAh/g Si) . Even adding 1000 ppm water did not lead to rapid capacity fade in cells undergoing cycle life tests. Nano-FTIR spectroscopy revealed chemical and structural differences in the SEI for cells with 1000 ppm water compared to 200-300 ppm water. The SEI differences, including increased Li2O concentration, may have contributed to improved calendar life. This research reveals the capabilities of LHCEs to improve the calendar and cycle life of Si-based Li-ion batteries, despite the presence of a highly reactive contaminant.

25 ENERGY STORAGE↗
DOE OSTI2025

Enhanced Performance of Silicon Anodes through Hybrid Surface Engineering

Silicon (Si) is a promising anode material for nextgeneration lithium-ion batteries (LIBs) due to its high theoretical capacity. However, Si-containing anodes typically suffer from unacceptably short lives because of the unrestricted growth of the solid electrolyte interphase (SEI). Here, in this study, hybrid surface coatings are developed to stabilize the SEI in high loading pure Si anodes using atomic and molecular layer deposition. The coatings, consisting of LiF paired with lithicone, create an ionically conductive surface that enhances the capacity retention, rate performance, and longevity. Careful binder selection helps demonstrate the full utility of the coatings by enabling high loading electrodes to cycle continuously at current densities of 1200 mA/g Si . Uncoated controls, in comparison, fail within just 10 cycles at lower loadings. X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy are used to provide supporting evidence of the coating composition and efficacy. The data indicate that our lithicone coating is converted to Li 2 CO 3 upon cycling contributing to favorable LiF/Li 2 CO 3 interfaces that enhance the space-charge effect at the active material’s surface. When applied to electrodes made with thermally stable binders and increasingly higher loadings (approaching 5 mAh/cm 2 ), ion transport through the bulk electrode, rather than SEI growth, is shown to be the limiting factor. Furthermore, data suggests a favorable interaction between lithicone precursors and poly(acrylic acid) binders mitigates thermal decomposition at higher temperatures. The work presented here represents the successful realization of composite coatings containing LiF/Li 2 CO 3 components to stabilize high-loading Si anodes. This work helps inform advanced surface engineering strategies to achieve highly reversible, high-capacity Si anodes capable of fast charging for high-performance LIBs.

atomic layer deposition↗
DOE OSTI2025

Temperature-dependent solid electrolyte interphase reactions drive performance in lithium-mediated nitrogen reduction to ammonia

The solid electrolyte interphase (SEI) is a vital component to control mass transport and selectivity in the lithium-mediated reduction of N 2 to NH 3 (Li-N 2 R). Finding strategies that generate the optimal SEI, a complex network of organic and inorganic species, can potentially improve Li-N 2 R performance. Here, we unravel structure-property relationships of the SEI by correlating its composition with the NH 3 faradaic efficiency (FENH3). By modifying the reaction temperature, we alter electrolyte decomposition reactions and observe changes in the SEI that explain FE NH3 trends between electrolyte solvents. We quantify a complex reaction environment at elevated temperatures where SEI formation is counteracted by etching reactions. This tradeoff leads to temporal fluctuations of FE NH3 , but the maximal FE NH3 can reach up to 40%, the highest value reported for batch cells at ambient pressure, thus far. In conclusion, our work underscores the potential of novel electrolytes that steer SEI selectivity and, ultimately, improve Li-N 2 R performance.

electrocatalytic nitrogen reduction↗
DOE OSTI2026

Tuning Solid Electrolyte Interphase Formation before Plating Onset in Anode-Free Sodium Batteries

Sodium (Na) batteries are of growing interest due to the higher earth abundance of sodium than lithium, as well as their promising theoretical energy density when metallic Na anodes are used. However, Na plating and stripping are heavily influenced by the physicochemical properties of the solid electrolyte interphase (SEI), which is directly influenced by the solvent and salt used for the electrolyte. While most studies focus on the SEI that forms on the surface of Na metal after plating, we expand this analysis by identifying a nanoscale “pre-plating” SEI that forms on the current collector (CC) prior to the onset of Na plating. Here, we systematically investigate an array of Na salt and glyme solvents in the electrolyte and determine the associated impacts on pre-plating SEI formation on aluminum CCs. By combining analytical electrochemistry approaches with a multimodal suite of spectroscopy techniques (X-ray, infrared, and Raman), supported by density functional theory calculations, we reveal a direct correlation between the Na + coordination environment and pre-plating SEI composition. We find that longer-chain glymes produce larger proportions of organic alkoxide products in the interphase, consistent with increased Na + −glyme interactions, while the fraction of salt-derived inorganic products (e.g., NaF) correlates with Na + −anion coordination. These insights highlight the critical influence of electrolyte composition particularly solvent identity and Na + coordination on the initial SEI formation in anode-free Na batteries.

anode-free batteries↗
DOE OSTI2024

Making Plasticized Polymer Electrolytes Stable Against Sodium Metal for High‐Energy Solid‐State Sodium Batteries

Solid polymer electrolytes based on plastic crystals are promising for solid-state sodium metal (Na 0 ) batteries, yet their practicality has been hindered by the notorious Na 0 -electrolyte interface instability issue, the underlying cause of which remains poorly understood. Here, in this study, by leveraging a model plasticized polymer electrolyte based on conventional succinonitrile plastic crystals, we uncover its failure origin in Na 0 batteries is associated with the formation of a thick and non-uniform solid electrolyte interphase (SEI) and whiskery Na 0 nucleation/growth. Furthermore, we design a new additive-embedded plasticized polymer electrolyte to manipulate the Na 0 deposition and SEI formulation. For the first time, we demonstrate that introducing fluoroethylene carbonate (FEC) additive into the succinonitrile-plasticized polymer electrolyte can effectively protect Na 0 against interfacial corrosion by facilitating the growth of dome-like Na 0 with thin, amorphous, and fluorine-rich SEIs, thus enabling significantly improved performances of Na//Na symmetric cells (1,800 h at 0.5 mA cm −2 ) and Na//Na 3 V 2 (PO 4 ) 3 full cells (93.0 % capacity retention after 1,200 cycles at 1 C rate in coin cells and 93.1 % capacity retention after 250 cycles at C/3 in pouch cells at room temperature). Our work provides valuable insights into the interfacial failure of plasticized polymer electrolytes and offers a promising solution to resolving the interfacial instability issue.

25 ENERGY STORAGE↗
DOE OSTI2025

Comparative Study of Vinylene Carbonate and Lithium Difluoro(oxalate)borate Additives in a SiO x /Graphite Anode Lithium-Ion Battery in the Presence of Fluoroethylene Carbonate

The SiO x /graphite composite is recognized as a promising anode material for lithium-ion batteries (LIBs), owing to the high theoretical capacity of SiO x combined with the excellent stability of graphite. However, the inherent disadvantage of volume expansion in silicon-based anodes places significant challenges on the solid electrolyte interphase (SEI) and severely degrades the electrochemical performance. Rational formulation of electrolyte, including its additives, is crucial in accommodating and optimizing the composition of the SEI and enhancing the cell performance. In this work, we present a comparative study of vinylene carbonate (VC) and lithium difluoro(oxalate)borate (LiDFOB) additives combined with fluoroethylene carbonate (FEC) in the electrolyte for SiO x /graphite∥LiNi 1–x–y–z Co x Mn y Al z O 2 full cells. VC outperformed LiDFOB as an additive, delivering higher capacity cycling, higher Coulombic efficiency, and better cycle stability up to 400 cycles. XPS and impedance analyses reveal that LiDFOB contributed to SEI/CEI with both a lower proportion of LiF and a higher proportion of poly(VC), which tended to produce higher cell impedance. XRD and XANES further indicated that using the LiDFOB additive, the NCMA cycled to a shallower degree than that of the VC additive. Although the VC additive maintained a higher capacity up to 400 cycles, microstrain and SEM analyses show a higher strained NCMA along with clear evidence of cracking over the surface of the NCMA particle in VC-based electrolyte but not in LiDFOB. In conclusion, this suggests that the negative influence of LiDFOB at the anode (inferior SEI) supersedes the negative impact of both a cracked NCMA and a deeper cycled NCMA and SiO x -based anode.

36 MATERIALS SCIENCE↗
DOE OSTI2024

In Situ Cyclized Polyacrylonitrile Coating: Key to Stabilizing Porous High-Entropy Oxide Anodes for High-Performance Lithium-Ion Batteries

High-entropy oxides (HEOs) composed of multiple metal elements have attracted great attention as anode materials for lithium-ion batteries (LIBs) due to the synergistic effects of various metal species. However, the practical applications of HEOs are still plagued by poor conductivity, unstable solid electrolyte interphase (SEI) and poor cycling stability. In this work, nanosized (FeCoNiCrMn) 3 O 4 HEO (NHEO) is prepared successfully by the NaCl-assisted mechanical ball-milling strategy. Novelly, polyacrylonitrile (PAN) is used as the binder and then in situ thermochemically cyclized to construct a cyclized PAN (cPAN) outer layer onto NHEO (NHEO-cPAN). The in situ formed cPAN coating not only improves the electrical conductivity, but also reinforces the structural and interfacial stability, and thereby, the resulted NHEO-cPAN electrode exhibits significantly enhanced rate and cyclic performance. Specifically, NHEO-PAN500 electrode delivers a high reversible capacity of 560 mAh g –1 at 5 A g –1 and a high-capacity retention of 83% over 800 cycles at 3 A g –1 . Furthermore, the structural evolution and electrochemical behavior of NHEO-PAN electrode during discharge/charge is systematically investigated by operando X-ray diffraction, in situ impedance spectroscopy and ex situ high-resolution transmission electron microscopy. Therefore, this work provides new insights into the engineering of electrode and interphase for high-performance HEO electrode materials, potentially enlightening the practical applications of HEO-based LIBs.

25 ENERGY STORAGE↗
DOE OSTI2025

Chemo‐Mechanics Interplay Dictates Interface Instability and Asymmetry in Plating and Stripping of Sodium Metal Electrodes

Abstract The development of practical sodium (Na) metal batteries is hindered by key challenges including dendrite growth, dead metal formation, and unstable solid electrolyte interphase (SEI) growth. A fundamental understanding of the chemo‐mechanical interactions at the Na/SEI interface is critical for designing stable Na metal electrodes. In this work, the coupled electrochemical‐mechanical processes governing the morphological evolution and stability of Na metal during plating and stripping are investigated. The heterogeneous nature of transport and morphological interactions at the Na/SEI interface is revealed to result in nonuniform mechanical overpotentials and reaction fronts, eventually leading to Na filaments or pits. The spatio‐temporal evolution of stress heterogeneities during Na plating and stripping is shown to be asymmetric, manifesting in varying morphological nonuniformities and instability modes. The crucial role of external pressure in modulating the electrochemical‐transport interactions, the mechanical response of Na, and the localized reaction currents and stresses at the Na/SEI interface is demonstrated. At different external pressure conditions, the correlation between transport heterogeneities in the SEI and the onset and propagation of interface instability has been delineated. This work highlights the need for synergistic tailoring of external pressure and SEI heterogeneity toward achieving stable electrodeposition and dissolution in Na metal electrodes.

Singla, Aditya [School of Mechanical Engineering P↗
DOE OSTI2025

Crossover Effects of Transition‐Metal Ions on Lithium‐Metal Anode in Localized High Concentration Electrolytes

Abstract The stability of the solid–electrolyte interphase (SEI) is critical to the cycle life of lithium‐metal batteries (LMBs). While the crossover effect of transition‐metal ions from cathode to anode is extensively studied in lithium‐ion batteries with graphite anodes, its impact on LMBs remains largely unexplored. Herein, this study investigates the electrochemical and chemical properties of SEI layers formed on lithium‐metal anodes in localized high‐concentration electrolytes (LHCEs) containing dissolved transition‐metal ions (Ni 2+ , Mn 2+ , and Co 2+ ). It is demonstrated that transition‐metal ions in LHCEs reduce the coulombic efficiency (CE) and significantly degrade the cycle life of LMBs. Time‐of‐flight secondary‐ion mass spectrometry (ToF‐SIMS) reveals that SEI structures differ depending on the dissolved TM ion, with Mn 2+ and Co 2+ inducing severe destabilization, and Ni 2+ exhibiting a less severe impact. These findings underscore the detrimental effects of transition‐metal crossover effects in LMB systems.

Guo, Zezhou [Materials Science and Engineering Pro↗
DOE OSTI2023

Delineating the Impact of Transition‐Metal Crossover on Solid‐Electrolyte Interphase Formation with Ion Mass Spectrometry

Abstract Lithium‐metal batteries (LMB) employing cobalt‐free layered‐oxide cathodes are a sustainable path forward to achieving high energy densities, but these cathodes exhibit substantial transition‐metal dissolution during high‐voltage cycling. While transition‐metal crossover is recognized to disrupt solid‐electrolyte interphase (SEI) formation on graphite anodes, experimental evidence is necessary to demonstrate this for lithium‐metal anodes. In this work, advanced high‐resolution 3D chemical analysis is conducted with time‐of‐flight secondary‐ion mass spectrometry (TOF‐SIMS) to establish spatial correlations between the transition metals and electrolyte decomposition products found on cycled lithium‐metal anodes. Insights into the localization of various chemistries linked to crucial processes that define LMB performance, such as lithium deposition, SEI growth, and transition‐metal deposition are deduced from a precise elemental and spatial analysis of the SEI. Heterogenous transition‐metal deposition is found to perpetuate both heterogeneous SEI growth and lithium deposition on lithium‐metal anodes. These correlations are confirmed across various lithium‐metal anodes that are cycled with different cobalt‐free cathodes and electrolytes. An advanced electrolyte that is stable to higher voltages is shown to minimize transition‐metal crossover and its effects on lithium‐metal anodes. Overall, these results highlight the importance of maintaining uniform SEI coverage on lithium‐metal anodes, which is disrupted by transition‐metal crossover during operation at high voltages.

Chemistry↗
DOE OSTI2026

Rational Design of Weakly‐Solvating Molecules for Salt‐In‐Pre‐Ionic‐Liquid Electrolytes for Li Metal Batteries

Lithium metal batteries (LMBs) promise step‐changes in energy densities but suffer from poor cycle life due to unstable electrolyte‐lithium interfaces. Conventional carbonate electrolytes exhibit excessive lithium‐ion solvation and low oxidative stability, leading to rapid capacity loss. Herein, we report a rationally designed weakly‐solvating cyclic sulfonamide, 1‐trifluoromethanesulfonyl)amide pyrrolidine (TFMSPyr), which integrates an electron‐withdrawing trifluoromethanesulfonyl functional group at pyrrolidinic‐N. TFMSPyr acts as a pre‐ionic‐liquid solvent that forms intrinsically localized, anion‐dominated solvation, coupling molecular architecture, solvation topology, and transport dynamics. As a result, LiFSI based salt‐in‐pre‐ionic‐liquid (SIPIL) electrolytes exhibit high lithium‐ion transference number, oxidative stability > 5 V versus Li/Li + and anion‐derived solid electrolyte interphases (SEI). Li||Cu cells with SIPIL deliver a first cycle Coulombic efficiency (CE) of ≈ 99% with average CE of 99.2% for 100 cycles, and lithium half‐cells with lithium iron phosphate (LFP) cathode exhibit 82% capacity retention after 400 cycles with CE of 99.98%. In anode‐free full cells, 95% of initial capacity is retained after 63 cycles with an average CE of 99.5%. These results demonstrate that molecular engineering of solvents offers a powerful pathway to stabilize lithium metal interfaces and enable practical Anodeless LMBs.

25 ENERGY STORAGE↗
DOE OSTI2025

Floatable Protective Layers: a Strategy to Minimize Solid Electrolyte Interphase Growth and Maximize the Lithium Utilization

Abstract Maximizing lithium (Li) utilization is crucial for enhancing the long‐term stability of Li‐based batteries. In anode‐free Li batteries (AFLBs), although the initial formation of solid electrolyte interphase (SEI) is beneficial on limiting further reaction between Li and electrolyte, large volume change of Li metal anode (LMA) during cycling often leads to continuous breakdown and re‐formation of SEI and formation of inactive Li, hindering its efficiency. In this study, a novel strategy is presented to protect Li metal by applying a floatable protection layer (FPL) on a copper substrate, enabling large Li particles to be primarily deposited below FPL, but SEI to be primarily formed above FPL. This approach effectively minimizes the direct contact between electrolyte and freshly deposited Li, therefore mitigating the continuous side reactions and early failure of AFLBs. As a result, Li consumption is minimized, and the overall stability of the battery is significantly enhanced. Further development of this approach can also be used to improve the performance of other Li‐based batteries for large‐scale applications.

Lim, Hyung‐Seok [Energy and Environment Directorat↗