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All sources NASA NTRS DOE OSTI

DOE OSTI2025

Electrolyte-driven interphase stabilization in high-voltage sodium-ion full cells

Sodium-ion batteries with a high-voltage O3-type layered oxide cathode paired with a hard carbon anode can offer high energy density; however, significant interfacial instabilities driven by electrode/electrolyte reactions limit a broader industrial adoption. Localized high concentration electrolytes (LHCEs) are a rational choice as they promote salt decomposition over solvent, forming stable, inorganic-rich electrode-electrolyte interphases (EEIs). We present here a comparison of high-voltage (4.2 V) hard carbon | NaNi 1/3 Fe 1/3 Mn 1/3 O 2 pouch cells in LHCEs and in a standard carbonate-based electrolyte by (i) examining the influence of diluent choice on the electrochemical performance of LHCEs and (ii) investigating how the electrolyte chemistry affects the composition and structure of EEIs formed. Importantly, LHCEs demonstrate superior electrochemical performance, achieving 37% higher capacity after 200 cycles (119 vs. 87 mA h g -1 ) compared to the carbonate-based electrolyte. The enhanced stabilization provided by LHCEs at the interface with high-voltage sodium layered oxide cathode is revealed by gas evolution measurements obtained through online electrochemical mass spectrometry (OEMS). Time-of-flight secondary ion mass spectrometry paired with focused ion beam and advanced statistical analyses reveal that the superior performance of LHCE stems from a robust, thin cathode electrolyte interphase formed on the sodium layered oxide cathode and a homogeneous solid electrolyte interphase formation on the hard carbon anode. Furthermore, this study highlights the critical importance of electrolyte design in interphase stabilization, which plays a key role in advancing sodium-ion batteries toward commercial viability.

25 ENERGY STORAGE↗

DOE OSTI2025

Interfacial Strength in Hierarchical Carbon Fiber Composites: Interplay of Interphase Modulus and Roughness

A facile, direct deposition approach that exploits van der Waals interactions between carbonaceous materials is utilized to create unidirectional hybrid carbon fiber composites. Two small molecule crosslinkers, a trifunctional aromatic (TL) and a difunctional aliphatic (DL) acyl chloride, are first utilized to create a crosslinked interphase with a softer and stiffer modulus respectively. TL crosslinked interphase with a higher modulus improved the tensile strength by 50%, despite non-covalent linking between fiber and matrix, elucidating the critical role of the interphase in alleviating modulus mismatch between the high modulus carbon fiber and the rubbery matrix. Fractional quantities of carbon nanotubes are additionally dispersed in the small molecule crosslinkers which behaved as a dispersant, helping introduce nanoasperities on the carbon fiber surface. Strong “pi-pi” interactions between CNTs and CF contributed to tensile properties, which are increased by 66% compared to the control. A cohesive zone model suggests that a stiffer interphase is better able to exploit surface heterogeneities and roughness on the fiber, synergistically enhancing interfacial strength.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Enhancing Composite Toughness Through Hierarchical Interphase Formation

High strength and ductility are highly desired in fiber-reinforced composites, yet achieving both simultaneously remains elusive. A hierarchical architecture is developed utilizing high aspect ratio chemically transformable thermoplastic nanofibers that form covalent bonding with the matrix to toughen the fiber-matrix interphase. The nanoscale fibers are electrospun on the micrometer-scale reinforcing carbon fiber, creating a physically intertwined, randomly oriented scaffold. Unlike conventional covalent bonding of matrix molecules with reinforcing fibers, here, the nanofiber scaffold is utilized - interacting non-covalently with core fiber but bridging covalently with polymer matrix - to create a high volume fraction of immobilized matrix or interphase around core reinforcing elements. This mechanism enables efficient fiber-matrix stress transfer and enhances composite toughness. Molecular dynamics simulation reveals enhancement of the fiber-matrix adhesion facilitated by nanofiber-aided hierarchical bonding with the matrix. The elastic modulus contours of interphase regions obtained from atomic force microscopy clearly indicate the formation of stiffer interphase. These nanoengineered composites exhibit a ≈60% and ≈100% improved in-plane shear strength and toughness, respectively. This approach opens a new avenue for manufacturing toughened high-performance composites.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Irreparable Interphase Chemistry Degradation Induced by Temperature Pulse in Lithium–Ion Batteries

While it is widely recognized that the operating temperature significantly affects the energy density and cycle life of lithium-ion batteries, the consequence of electrode-electrolyte interphase chemistry to sudden environmental temperature changes remains inadequately understood. Here, we systematically investigate the effects of a temperature pulse (T pulse) on the electrochemical performance of LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) pouch full cells. By utilizing advanced characterization tools, such as time-of-flight secondary-ion mass spectrometry, we reveal that the T pulse can lead to an irreversible degradation of cathode-electrolyte interphase chemistry and architecture. Despite negligible immediate impacts on the solid-electrolyte interphase (SEI) on graphite anode, aggregated cathode-to-anode chemical crossover gradually degrades the SEI by catalyzing electrolyte reduction decomposition and inducing metallic dead Li formation because of insufficient cathode passivation after the T pulse. Consequently, pouch cells subjected to the T pulse show an inferior cycle stability to those free of the T pulse. Furthermore, this work unveils the effects of sudden temperature changes on the interphase chemistry and cell performance, emphasizing the importance of a proper temperature management in assessing performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2025

Cross-scale modeling and experimental integration for advancing cathode electrolyte interphase studies in high energy density lithium-ion batteries

Electrochemical interfaces are critical to the performance and durability of lithium-ion batteries (LIBs). The solid electrode-electrolyte interphase (SEI and CEI) structures that form during cycling can passivate reactive surfaces, ensuring safe operation, but also may contribute to performance degradation. Understanding the microscopic factors influencing interphase formation, growth, and evolution is essential for balanced battery design. While significant research has focused on the anode-electrolyte interphase (SEI), the cathode-electrolyte interphase (CEI) remains less explored, despite its importance in high-voltage and advanced battery technologies. Challenges in conducting in-situ or operando experiments arise from the occluded nature of these interfaces and the long timescales involved, often leading to biased interpretations. A validated multi-scale, multi-physics modeling approach, integrated with advanced characterization techniques, can effectively elucidate the intrinsic stability of electrolyte and cathode surfaces, the impact of chemical heterogeneity, and the role of microstructural features on CEI performance. In conclusion, this article reviews current modeling and simulation strategies for studying CEI in advanced LIBs and highlights opportunities for future methodological advancements and experimental integration.

Cathode-electrolyte interphase↗

DOE OSTI2025

Minimization of Cathode|Solid-Electrolyte Interfacial Delamination through the Application of Interphase Layers

Next-generation lithium-ion batteries are expected to use solid electrolytes (SEs) to enable higher energy density and extreme fast-charge capabilities. One major mode of degradation at the cathode|SE interface is delamination between the cathode active materials and SEs, which leads to performance decay. Experimental observations indicate that implementation of interphase layers can minimize the cathode|SE delamination induced capacity fade. A multiscale computational methodology is developed here to investigate the applicability of boron substituted lithium carbonate (Li 2+x B x C 1–x O 3 , x = 0.5, or LBCO) to minimize the delamination at the cathode|SE interface. Atomistic simulations indicate that the fracture energies at both the cathode|LBCO and LBCO|SE interfaces are higher than those at the cathode|SE interface, which reduces the extent of delamination. Mesoscale simulations indicate that, apart from increasing the fracture energy, decreasing the evolution of strain energy by lowering the elastic modulus of the interphase layer can also minimize the extent of delamination at the cathode|SE interface. However, the adoption of an interphase layer with high ionic conductivity is necessary to minimize the ohmic losses during operation at higher current densities. This study provides guidance on selecting interphase layers with specific properties and thicknesses to minimize both interfacial delamination and impedance growth.

LBCO↗

DOE OSTI2022

Forming Interphase Microgrids in Distribution Systems Using Cooperative Inverters

Interphase-microgrids formed by three islanded single-phase feeders in distribution systems are proposed in this paper. Loss of utility caused by natural and human-made disasters may isolate each residential subdivision from the utility. In this case, the household loads are supplied by distributed generation (DG) units which may not be enough to meet the load demand. This can lead to deviations in voltage and frequency, and the deviations may vary for each phase. The proposed solution is to form an interphase-microgrid by seamlessly interconnecting the islanded single-phase feeders. This interphase-microgrid can effectively balance the load demands and DG generation in distribution systems after losing the utility supply. This paper presents different case studies to demonstrate the viability of forming interphase-microgrids for residential distribution systems.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2023

Irreparable Interphase Chemistry Degradation Induced by Temperature Pulse in Lithium‐Ion Batteries

Abstract While it is widely recognized that the operating temperature significantly affects the energy density and cycle life of lithium‐ion batteries, the consequence of electrode‐electrolyte interphase chemistry to sudden environmental temperature changes remains inadequately understood. Here, we systematically investigate the effects of a temperature pulse (T pulse) on the electrochemical performance of LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) pouch full cells. By utilizing advanced characterization tools, such as time‐of‐flight secondary‐ion mass spectrometry, we reveal that the T pulse can lead to an irreversible degradation of cathode‐electrolyte interphase chemistry and architecture. Despite negligible immediate impacts on the solid‐electrolyte interphase (SEI) on graphite anode, aggregated cathode‐to‐anode chemical crossover gradually degrades the SEI by catalyzing electrolyte reduction decomposition and inducing metallic dead Li formation because of insufficient cathode passivation after the T pulse. Consequently, pouch cells subjected to the T pulse show an inferior cycle stability to those free of the T pulse. This work unveils the effects of sudden temperature changes on the interphase chemistry and cell performance, emphasizing the importance of a proper temperature management in assessing performance.

Cui, Zehao↗

DOE OSTI2023

Interphase Stabilization of LiNi 0.5 Mn 1.5 O 4 Cathode for 5 V–Class All–Solid–State Batteries

Employing high voltage cobalt-free spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) as a cathode is promising for high energy density and cost-effectiveness, but it has challenges in all-solid-state batteries (ASSBs). Here, it is revealed that the limitation of lithium argyrodite sulfide solid electrolyte (Li 6 PS 5 Cl) with the LNMO cathode is due to the intrinsic chemical incompatibility and poor oxidative stability. Through a careful analysis of the interphase of LNMO, it is elucidated that even the halide solid electrolyte (Li 3 InCl 6 ) with high oxidative stability can be decomposed to form resistive interphase layers with LNMO in ASSBs. Interestingly, with Fe-doping and a Li 3 PO 4 protective layer coating, LNMO with Li 3 InCl 6 displays stable cycle performance with a stabilized interphase at a high voltage (≈4.7 V) in ASSBs. The enhanced interfacial stability with the extended electrochemical stability window through doping and coating enables high electrochemical stability with LNMO in ASSBs. Furthermore, this work provides guidance for employing high-voltage cathodes in ASSBs and highlights the importance of stable interphases to enable stable cycling in ASSBs.

25 ENERGY STORAGE↗

DOE OSTI2025

An Atomistic Study of Reactivity in Solid-State Electrolyte Interphase Formation for Li/Li7P3S11

Lithium metal batteries offer superior volumetric and gravimetric specific capacities compared to those based on traditional graphite anodes. Although advancements in solid-state electrolytes address safety concerns, challenges remain, particularly regarding interphase formation in lithium metal anodes. This work presents a computational framework based on high-throughput first-principles density functional theory and machine-learning interatomic potentials (MLIPs) including automated iterative, active learning to enable robust computational exploration of interphase formation between lithium metal anodes and an inorganic solid-state electrolyte. As a demonstration, we apply the framework to a Li/Li7P3S11 interface and find that it accurately identifies the experimentally observed, thermodynamically stable interphase products as well as their overall spatial arrangement within a heterogeneous, amorphous layered structure, with Li2S domains of nanocrystallinity. Our simulations show two stages, a fast and slow diffusion reaction regime, that corroborate the relative phase formation rate of Li x P, Li2S, and Li3P. Using the Onsager transport theory, we capture time-dependent ionic diffusion within the reacting interface, including cross-correlation effects. We found that cross-correlation effects between Li-P and P-S ionic motion significantly influence P-ion diffusion, making it highly sensitive to the local environment and potentially leading to "kinetic trapping" of Li-P phases. The passivation of the interface is shown as the ionic fluxes all approach zero, effectively halting interphase growth.

Diffusion↗

DOE OSTI2020

Electroanalytical Measurement of Interphase Formation at a Li Metal–Solid Electrolyte Interface

The interphase between Li metal and solid electrolytes dictates performance in Li metal batteries. For the solid electrolyte Lipon, in this study we electroanalytically measure a capacity loss of 1.03 ± 0.16 μAh/cm 2 when Lipon first contacts Li metal. Assuming this capacity is all lost to interphase formation, this corresponds to a maximum Li consumption of 5.0 ± 0.8 nm to form an interphase ~4.7 nm thick. From dynamic electrochemical impedance spectroscopy (dEIS) during Li plating, we determine that nonlinear chaotic spectra demark this interphase formation and that this occurs immediately upon initiation of Li plating. dEIS also reveals interfacial resistance during both plating and stripping that decreases as the amount of plated Li increases.

25 ENERGY STORAGE↗

DOE OSTI2024

Multiscale modeling of metal-hydride interphases—quantification of decoupled chemo-mechanical energies

Abstract The quantification of interphase properties between metals and their corresponding hydrides is crucial for modeling the thermodynamics and kinetics of the hydrogenation processes in solid-state hydrogen storage materials. In particular, interphase boundary energies assume a pivotal role in determining the kinetics of nucleation, growth, and coarsening of hydrides, alongside accompanying morphological evolution during hydrogenation. The total interphase energy arises from both chemical bonding and mechanical strains in these solid-state systems. Since these contributions are usually coupled, it is challenging to distinguish via conventional computational approaches. Here, a comprehensive atomistic modeling methodology is developed to decouple chemical and mechanical energy contributions using first-principles calculations, of which feasibility is demonstrated by quantifying chemical and elastic strain energies of key interfaces within the FeTi metal-hydride system. Derived materials parameters are then employed for mesoscopic micromechanical analysis, predicting crystallographic orientations in line with experimental observations. The multiscale approach outlined verifies the importance of the chemo-mechanical interplay in the morphological evolution of growing hydride phases, and can be generalized to investigate other systems. In addition, it can streamline the design of atomistic models for the quantitative evaluation of interphase properties between dissimilar phases and allow for efficient predictions of their preferred phase boundary orientations.

36 MATERIALS SCIENCE↗

DOE OSTI2025

An infrared, Raman, and X-ray database of battery interphase components

Further improvements to lithium-ion and emerging battery technologies can be enabled by an improved understanding of the chemistry and working mechanisms of interphases that form at electrochemically active battery interfaces. However, it is difficult to collect and interpret spectra of interphases for several reasons, including the presence of a variety of compounds. To address this challenge, we herein present a vibrational spectroscopy and X-ray diffraction data library of ten compounds that have been identified as interphase constituents in lithium-ion or emerging battery chemistries. The data library includes attenuated total reflectance Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray diffraction data, collected in inert atmospheres provided by custom sample chambers. The data library presented in this work (and online repository) simplifies access to reference data that is otherwise either diffusely spread throughout the literature or non-existent, and provides energy storage researchers streamlined access to vital interphase-relevant data that can accelerate battery research efforts.

25 ENERGY STORAGE↗

NASA NTRS1991

Interphase layer optimization for metal matrix composites with fabrication considerations

A methodology is presented to reduce the final matrix microstresses for metal matrix composites by concurrently optimizing the interphase characteristics and fabrication process. Application cases include interphase tailoring with and without fabrication considerations for two material systems, graphite/copper and silicon carbide/titanium. Results indicate that concurrent interphase/fabrication optimization produces significant reductions in the matrix residual stresses and strong coupling between interphase and fabrication tailoring. The interphase coefficient of thermal expansion and the fabrication consolidation pressure are the most important design parameters and must be concurrently optimized to further reduce the microstresses to more desirable magnitudes.

Morel, M.↗

NASA NTRS1991

Concurrent tailoring of fabrication process and interphase layer to reduce residual stresses in metal matrix composites

A methodology is presented to reduce the residual matrix stresses in continuous fiber metal matrix composites (MMC) by optimizing the fabrication process and interphase layer characteristics. The response of the fabricated MMC was simulated based on nonlinear micromechanics. Application cases include fabrication tailoring, interphase tailoring, and concurrent fabrication-interphase optimization. Two composite systems, silicon carbide/titanium and graphite/copper, are considered. Results illustrate the merits of each approach, indicate that concurrent fabrication/interphase optimization produces significant reductions in the matrix residual stresses and demonstrate the strong coupling between fabrication and interphase tailoring.

Saravanos, D. A.↗

NASA NTRS1991

Interphase layer optimization for metal matrix composites with fabrication considerations

Morel, Michael↗

NASA NTRS1995

A Porous Ceramic Interphase for SiC/Si(sub 3)N(sub 4) Composites

A suitable interphase material for non-oxide ceramic-matrix composites must be resistant to oxidation. This means it must exhibit a slow rate of oxidation, and its oxidation product must be such as to ensure that the system survives oxidation when it does occur. Because the current benchmark interphase materials, carbon and boron nitride, lack these qualities, a porous fiber coating was developed to satisfy both the mechanical and oxidative requirements of an interphase for the SiC/SiC and SiC/Si2N4 composites that are of interest to NASA. This report presents the interphase microstructure achieved and the resulting characteristics of fiber push-out from a matrix of reaction-bonded silicon nitride (RBSN), both as-fabricated and after substantial annealing and oxidation treatments.

Ogbuji, Linus U. J. T.↗

NASA NTRS2000

Room and Elevated Temperature Tensile Properties of Single Tow Hi-Nicalon, Carbon Interphase, CVI SiC Matrix Minicomposites

Single tow Hi-Nicalon(TM), C interphase, CVI SiC matrix minicomposites were tested in tension at room temperature, 700 C, 950 C, and 1200 C in air. Monotonic loading with modal acoustic emission monitoring was performed at room temperature in order to determine the dependence of matrix cracking on applied load. Modal acoustic emission was shown to correlate directly with the number of matrix cracks formed. Elevated temperature constant load stress-rupture and low-cycle fatigue experiments were performed on precracked specimens. The elevated temperature rupture behavior was dependent on the precrack stress, the lower precrack stress resulting in longer rupture life for a given stress. It was found that the rupture lives of C-interphase Hi-Nicalon(TM) minicomposites were superior to C-interphase Ceramic Grade Nicalon(TM) minicomposites and inferior to those of BN-interphase Hi-Nicalon(TM) minicomposites.

Martinez-Fernandez, J.↗