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174 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Mixed-anion electrolytes: from bulk speciation to interfacial dynamics in divalent metal electrodeposition

Mixing anions is emerging as a promising strategy for multivalent electrolyte design, allowing for adjustment of the solvation structure of bulk cations and enhancing the efficiency of electrochemical processes (e.g. metal deposition for batteries and catalysis). Further progress in electrolyte development requires a fundamental understanding of how tailored electrolyte speciation in mixed anion systems can modify the dynamic electrochemical interface during metal cycling. In this study, we present an anode-focused mechanistic study of exemplar Mg electrolytes containing three different secondary anions, correlating electrochemical behavior with bulk speciation and operando interfacial dynamics. Electrospray Ionization-Mass Spectrometry (ESI-MS) results reveal a general trend of forming mixed anion contact ion pairs (CIPs) across various anions, with the extent of ion pairing influenced by the association strength of the secondary anion. Operando multiharmonic electrochemical quartz crystal microbalance with dissipation (EQCM-D) reveals how these bulk species influence interfacial mass uptake, viscoelasticity, and solvent-coupled hydrodynamic behavior during deposition and stripping. The results indicate that Mg-containing ion pairs and solvated complexes shape adsorption, nucleation, and deposit growth, leading to distinct anion-dependent interphases ranging from more permeable, solvent-coupled layers to relatively compact and rigid deposits. This work establishes a quantitative link between bulk speciation and interfacial dynamics in divalent metal electrodeposition and provides mechanistic guidance for electrolyte design.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1973

Pitting of titanium. I - Titanium-foil experiments. II - One-dimensional pit experiments.

Pitting experiments were conducted with strips of titanium foil in beakers containing chloride, bromide, or iodide solutions. The potentials were determined in reference to the saturated calomel electrode. Corrosion occurred at the edge of a foil specimen when it was maintained at a potential between the steady-state pitting potential of about 0.9 V and a potential of about 1.4 V in neutral bromide solution. A model is discussed to account for the complex relationships observed in the experiments. Conclusions based on experiments conducted with one-dimensional pits at the ends of insulated titanium pencils in the anode-facing-up position are also presented.

Beck, T. R.↗
DOE OSTI2024

Study of Void Formation at the Lithium|Solid Electrolyte Interface

There is growing recognition of the critical role of void formation in lithium metal anodes in solid-state batteries and its impact on electrochemical performance. While experimental studies have demonstrated the challenges ensuing from void formation at the lithium metal interface with the solid electrolyte, there is a need to understand and quantify the role of intrinsic transport properties in lithium metal and the impact of external stimuli, such as temperature, pressure, and current density. Here, we develop this understanding by constructing a phase field-based model that captures the evolution of void domains at the lithium-solid electrolyte interface. Growth of the pores is driven by the fast removal of lithium from the interface during stripping at high current densities. Relative magnitudes of the bulk and surface lithium diffusivities, along with the applied current density, dictate the final pore morphology. Increasing the temperature results in faster diffusion, while external applied pressure causes creep flow of lithium, both of which help to mitigate the evolution of voids by quickly transporting metal from the bulk to the interface. Finally, a phase map as a function of temperature and pressure is developed as a guide to determine the regions that can lead to the stable cycling of lithium metal.

25 ENERGY STORAGE↗
DOE OSTI2024

Potential–Dependent BDAC Adsorption on Zinc Enabling Selective Suppression of Zinc Corrosion for Energy Storage Applications

Utility-scale zinc (Zn) batteries are a promising solution to address the problem of intermittency of renewable energy sources; however, Zn-metal anodes in these batteries suffer from capacity loss due to spontaneous corrosion of the Zn especially when high-surface area anode configurations are employed. Additionally, Zn dendrites are known to form during battery charging limiting the cycle-life of these batteries. Electrolyte additives have been explored that prevent aforementioned issues, but these too come at a cost, i.e., surface-blocking additives polarize the electrode surface leading to loss in the voltaic and energy efficiencies of the battery. In this contribution, a novel electrolyte additive, benzyldimethylhexadecylammonium chloride (BDAC), is investigated for its ability to suppresses corrosion of Zn in an acidic (pH = 3) electrolyte. An attribute of BDAC distinct from previously studied additives is that it selectively suppresses electrochemical activity when the Zn electrode is at its corrosion potential; however, during high-rate Zn deposition (charging) or stripping (discharging), BDAC is essentially deactivated and thus it does not appreciably polarize the electrode surface, thus minimizing voltaic efficiency losses. This selective corrosion suppression behavior is explored using slow-scan voltammetry, which reveals hysteresis implying a potential- or current-dependent BDAC adsorption mechanism in which BDAC reaches higher surface coverages when the partial currents at the Zn surface are low (e.g., at or near the corrosion potential), but BDAC coverage is reduced considerably when the Zn deposition or stripping rates are increased. Numerical simulations of the BDAC diffusion-adsorption process corroborate this mechanism. Ramifications of our approach to the selective suppression of Zn dendrites are discussed.

25 ENERGY STORAGE↗
DOE OSTI2023

Interface Design for High‐Performance All‐Solid‐State Lithium Batteries

All‐solid‐state batteries suffer from high interface resistance and lithium dendrite growth leading to low Li plating/stripping Coulombic efficiency (CE) of <90% and low critical current density at high capacity. Here, in this work, both challenges are simultaneously addressed and the Li plating/stripping CE is significantly increased to 99.6% at 0.2 mA cm −2 /0.2 mAh cm −2 , and critical current density (CCD) of > 3.0 mA cm −2 /3.0 mAh cm −2 by inserting a mixed ionic‐electronic conductive (MIEC) and lithiophobic LiF‐C‐Li 3 N‐Bi nanocomposite interlayer between Li 6 PS 5 Cl electrolyte and Li anode. The highly lithiophobic LiF‐C‐Li 3 N‐Bi interlayer with high ionic conductivity (10 −5 S cm −1 ) and low electronic conductivity (3.4×10 −7 S cm −1 ) enables Li to plate on the current collector (CC) surface rather than on Li 6 PS 5 Cl surface avoiding Li 6 PS 5 Cl electrolyte reduction. During initial Li plating on CC, Li penetrates into porous LiF‐C‐Li 3 N‐Bi interlayer and lithiates Bi nanoparticles into Li 3 Bi. The lithiophilic Li 3 Bi and Li 3 N nanoparticles in LiF‐C‐Li 3 N‐Li 3 Bi sub‐interlayer will move to CC along with plated Li, forming LiF‐C/Li 3 N‐Li 3 Bi lithiophobic/lithiophilic sublayer during the following Li stripping. This interlayer enables Co 0.1 Fe 0.9 S 2 /Li 6 PS 5 Cl/Li cell with an areal capacity of 1.4 mAh cm −2 to achieve a cycle life of >850 cycles at 150 mA g −1 . The lithiophobic/lithiophilic interlayer enables solid‐state metal batteries to simultaneously achieve high energy and long cycle life.

25 ENERGY STORAGE↗
DOE OSTI2020

Quantification of Inactive Lithium and Solid–Electrolyte Interphase Species on Graphite Electrodes after Fast Charging

Rapid charging of Li-ion batteries is limited by lithium plating on graphite anodes, whereby Li+ ions are reduced to Li metal on the graphite particle surface instead of inserting between graphitic layers, which directly contributes to cell capacity loss because of the low reversibility of the Li plating/stripping process. Furthermore, precisely identifying the onset and amount of Li plating is therefore vital in order to remedy these issues. We demonstrate a titration technique with a detection limit of 20 nmol (5 × 10 –4 mAh) of Li that can be used to quantify inactive Li that remains on the graphite electrode after fast charging. The titration is extended to quantify the total amount of solid carbonate species and lithium acetylide (Li 2 C 2 ) within the solid–electrolyte interphase (SEI), and electrochemical modeling is used to determine the Li plating exchange current density (10 A/m 2 ) and stripping efficiency (65%) of plated Li metal on graphite. These techniques provide a highly accurate measure of the onset of Li plating and quantitative insight into graphite SEI evolution during fast charging.

25 ENERGY STORAGE↗
DOE OSTI2023

Stable Lithium Plating in “Lithium Metal-Free” Solid-State Batteries Enabled by Seeded Lithium Nucleation

In the “Li 0 -free” architecture, cells are manufactured with a bare anode current collector and the Li metal anode is plated in situ during the first charging step. While this architecture has many attractive qualities from manufacturing and energy density perspectives, stable Li plating in solid-state “Li 0 -free” cells can be challenging. It is generally accepted that the Li overpotential affects Li homogeneity in “Li 0 -free” cells. We demonstrate that the nucleation overpotential for Li plating in solid-state “Li 0 -free” cells using commercial current collectors can be eliminated by introducing metal clusters that guide Li nucleation. Au is used as model alloying metal cluster. Here, we demonstrate stable Li plating with thickness 16.5 μ m (3.3 mAh cm −2 ) in oxide solid-state electrolyte “Li 0 -free” cells enabled by Au metal clusters. It is shown that 97% of the in situ plated Li can be reversibly stripped at 60 °C and 2.5 MPa. Conversely, Au interlayers which are flat and continuous instead of clustered in morphology consistently showed short-circuiting during in situ Li plating, limiting Li electrodeposition to <0.1 mAh cm −2 . These results can help guide future studies of Li nucleation and growth at solid/solid interfaces, as well as offer alternative manufacturing pathways for “Li 0 -free” solid-state batteries.

25 ENERGY STORAGE↗
NASA NTRS1990

Dry compliant seal for phosphoric acid fuel cell

A dry compliant overlapping seal for a phosphoric acid fuel cell preformed f non-compliant Teflon to make an anode seal frame that encircles an anode assembly, a cathode seal frame that encircles a cathode assembly and a compliant seal frame made of expanded Teflon, generally encircling a matrix assembly. Each frame has a thickness selected to accommodate various tolerances of the fuel cell elements and are either bonded to one of the other frames or to a bipolar or end plate. One of the non-compliant frames is wider than the other frames forming an overlap of the matrix over the wider seal frame, which cooperates with electrolyte permeating the matrix to form a wet seal within the fuel cell that prevents process gases from intermixing at the periphery of the fuel cell and a dry seal surrounding the cell to keep electrolyte from the periphery thereof. The frames may be made in one piece, in L-shaped portions or in strips and have an outer perimeter which registers with the outer perimeter of bipolar or end plates to form surfaces upon which flanges of pan shaped, gas manifolds can be sealed.

Granata, Jr., Samuel J.↗
DOE OSTI2020

First-principles Modeling and Design of Solid-State Interfaces for the Protection and Use of Lithium Metal Anodes

Li-ion batteries are one of the most advanced energy storage technologies in use today. Li-ion batteries are used in a multitude of applications ranging from consumer electronics, medical devices, sensors and grid storage. However, improving the capacity and energy density delivered by current Li-ion technology requires advanced materials research into novel chemical systems. In this project we have focused particularly in the use of solid-state electrolytes with lithium metal electrodes. Research into all solid-state batteries (ASSB) with Li metal electrodes has significantly expanded in recent years, however most studies reported experimental findings, which left substantial room for theoretical and modeling work as a tool to understand and determine design principles allowing reliable and safe use of ASSBs with Li metal. Among the remaining obstacles preventing reliable use of ASSBs with a Li metal electrode, the stability of the interface between the solid electrolyte and Li metal, and the propagation/dendrite formation of Li metal and resulting mechanical degradation of the electrolyte are key phenomenon that are yet to be fully understood. In the current project we have addressed these two coupled phenomena using first principles calculations and mesoscale continuum modeling. We have obtained chemical and electrochemical stability windows for several solid electrolyte materials. Additionally, from mathematical and numerical modeling of Li protrusion and dendrite initiation during plating and stripping we have determined design criteria in terms of chemical, electrochemical, and mechanical properties and operating conditions for which stable deposition can occur. We also considered the effects of mixed electronic-ionic conduction in solid electrolytes, which has more recently been suggested as another important mechanism involved in ASSB failure. Throughout our work we have successfully addressed important questions necessary for the use of ASSB’s. We have determined guiding principles for materials properties and operating conditions necessary to operate ASSB’s. And have proposed novel solid electrolyte materials with predicted chemical stability an ionic conductivity. Although this represents significant progress in our understanding, open questions remain in order to fully develop reliable and safely operate ASSBs with Li metal. Future work, building on this project will require further experimental, theoretical and simulation efforts to address remaining questions.

25 ENERGY STORAGE↗
DOE OSTI2020

Stable Potassium Metal Anodes with an All-Aluminum Current Collector through Improved Electrolyte Wetting

This is the first report of successful potassium metal battery anode cycling with an aluminum-based rather than copper-based current collector. Dendrite-free plating/stripping is achieved through improved electrolyte wetting, employing an aluminum-powder-coated aluminum foil “Al@Al,” without any modification of the support surface chemistry or electrolyte additives. The reservoir-free Al@Al half-cell is stable at 1000 cycles (1950 h) at 0.5 mA cm -2 , with 98.9% cycling Coulombic efficiency and 0.085 V overpotential. The pre-potassiated cell is stable through a wide current range, including 130 cycles (2600 min) at 3.0 mA cm -2 , with 0.178 V overpotential. Al@Al is fully wetted by a 4 m potassium bis(fluorosulfonyl)imide-dimethoxyethane electrolyte (θCA = 0°), producing a uniform solid electrolyte interphase (SEI) during the initial galvanostatic formation cycles. On planar aluminum foil with a nearly identical surface oxide, the electrolyte wets poorly (θCA = 52°). This correlates with coarse irregular SEI clumps at formation, 3D potassium islands with further SEI coarsening during plating/stripping, possibly dead potassium metal on stripped surfaces, and rapid failure. The electrochemical stability of Al@Al versus planar Al is not related to differences in potassiophilicity (nearly identical) as obtained from thermal wetting experiments. Additionally, planar Cu foils are also poorly electrolyte-wetted and become dendritic. The key fundamental takeaway is that the incomplete electrolyte wetting of collectors results in early onset of SEI instability and dendrites.

25 ENERGY STORAGE↗
DOE OSTI2021

The effect of aspect ratio on the mechanical behavior of Li metal in solid-state cells

The Li metal anode is necessary for solid-state batteries to dramatically exceed the energy density of state-of-the-art conventional Li-ion batteries. To enable the Li metal anode, the mechanical properties of Li metal under compression in a commercially relevant cell configuration must be determined. This work examines the compression creep behavior of Li metal coupled with a relevant model solid-state electrolyte (Li 6.5 La 3 Ta 0.5 Zr 1.5 O 12 ) and current collector (Ni) as a function of applied stress (1–10 MPa) and Li foil thickness (100–700 μm). At 1 MPa applied stress, the strain rate of all Li foil thicknesses under compression was almost four orders of magnitude lower than what is predicted from tensile creep tests. Steady-state creep behavior was observed for Li foil ≥350 μm at 5 MPa and ≥250 μm at 10 MPa. Conversely, sustained creep deformation was not observed for 100 and 150 μm Li foils at any applied stress. It is suggested that friction at the Li/LLZO and Li/Ni interfaces leads to the formation of hydrostatic stress that controls Li deformation at low aspect ratios. Finally, these results have implications for battery pack stack pressure requirements, particularly relating to void formation during stripping and Li metal filament penetration during plating.

25 ENERGY STORAGE↗
NASA NTRS2008

Chemical Passivation of Li(exp +)-Conducting Solid Electrolytes

Plates of a solid electrolyte that exhibits high conductivity for positive lithium ions can now be passivated to prevent them from reacting with metallic lithium. Such passivation could enable the construction and operation of high-performance, long-life lithium-based rechargeable electrochemical cells containing metallic lithium anodes. The advantage of this approach, in comparison with a possible alternative approach utilizing lithium-ion graphitic anodes, is that metallic lithium anodes could afford significantly greater energy-storage densities. A major impediment to the development of such cells has been the fact that the available solid electrolytes having the requisite high Li(exp +)-ion conductivity are too highly chemically reactive with metallic lithium to be useful, while those solid electrolytes that do not react excessively with metallic lithium have conductivities too low to be useful. The present passivation method exploits the best features of both extremes of the solid-electrolyte spectrum. The basic idea is to coat a higher-conductivity, higher-reactivity solid electrolyte with a lower-conductivity, lower-reactivity solid electrolyte. One can then safely deposit metallic lithium in contact with the lower-reactivity solid electrolyte without incurring the undesired chemical reactions. The thickness of the lower-reactivity electrolyte must be great enough to afford the desired passivation but not so great as to contribute excessively to the electrical resistance of the cell. The feasibility of this method was demonstrated in experiments on plates of a commercial high-performance solid Li(exp +)- conducting electrolyte. Lithium phosphorous oxynitride (LiPON) was the solid electrolyte used for passivation. LiPON-coated solid-electrolyte plates were found to support electrochemical plating and stripping of Li metal. The electrical resistance contributed by the LiPON layers were found to be small relative to overall cell impedances.

West, William↗