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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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33 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Measuring the buried interphase between solid electrolytes and lithium metal using neutrons

Interfaces are the key to next-generation high-energy batteries including solid-state Li metal batteries. In solid-state batteries, the buried nature of solid–solid electrolyte–electrode interfaces makes studying them difficult. Neutrons have significant potential to non-destructively probe these buried solid–solid interfaces. This work presents a comparative study using both neutron depth profiling (NDP) and neutron reflectometry (NR) to study a model lithium metal–lithium phosphorus oxynitride (LiPON) solid electrolyte system. In the NDP data, no distinct interphase is observed at the interface. NR shows a difference between electrodeposited, and vapor deposited LiPON–Li interfaces but finds both are gradient interphases that are less than 30 nm thick. Additional simulations of the LiPON–Li 2 O–Li system demonstrate that NDP has an excellent resolution in the 50 nm–1 μm regime while NR has an ideal resolution from 0.1–200 nm with different sample requirements. Together NDP and NR can provide a complementary understanding of interfaces between Li metal and solid electrolytes across relevant length scales.

Westover, Andrew S. [Oak Ridge National Laboratory↗
DOE OSTI2021

An ultrathin solid-state electrolyte film coated on LiNi 0.8 Co 0.1 Mn 0.1 O 2 electrode surface for enhanced performance of lithium-ion batteries

We report layered Ni-rich oxide is a promising cathode material for lithium-ion batteries (LIBs) of high energy density, yet its poor electrochemical stability induced by electrode-electrolyte interfacial degradation has still needed to be addressed. Surface coating is one of the powerful techniques to tackle this issue, nevertheless, it has been extensively used on particle but not electrode regarding a larger area of protection. Herein, we have covered a nano-scaled layer of lithium phosphorus oxynitride (LiPON) on the electrode level of LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM) surface and found lower impedance, longer cycle life, and better safety for treated battery. Most notably, such an NCM-LiPON based 1.3 Ah pouch cell delivers an energy density of 364.4 Wh kg -1 (based on positive and negative materials), along with the retention of 80.0% over 745 cycles at 0.5 C-rate, which is 1.3 times longer than the bare one. This results from modification of both superficial cathode-electrolyte interphase (CEI) and structure stabilization of general particle surface, therefore, role of conformal coating upon electrode surface should be highlighted.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Oxygen Vacancy Evolution at Li x V 2 O 5 /LiPON Solid State Electrochemical Interfaces Using Depth Resolved Cathodoluminescence Spectroscopy

The formation of oxygen vacancies at buried LiPON/ Li x V 2 O 5 interfaces has been observed on a near-nanometer scale and nondestructively using depth-resolved cathodoluminescence spectroscopy (DRCLS) and interfacial markers. Before electrochemical cycling, as-deposited LiPON/Li x V 2 O 5 exhibits a 1.6 eV defect optical emission, which density functional theory calculations identify as originating from oxygen vacancies. This defect appears first within a few nanometers of the buried LiPON/Li x V 2 O 5 interface without cycling, indicating that spontaneous O diffusion from the Li x V 2 O 5 lattice into LiPON may have caused these interface-localized oxygen vacancy defects. DRCLS measured the intensity and spatial distribution of this oxygen vacancy signal as a function of electrochemical cycling in a LiPON/Li x V 2 O 5 half-cell, showing oxygen vacancy signal increasing and moving deeper into the electrode with increased cycle number. Significant electrochemical irreversibility was also observed, with poor Coulombic efficiency and a 15% drop in capacity over 50 cycles. Theoretical simulations predict that the presence of oxygen vacancies increases the energy barrier for lithium diffusion significantly, indicating that this aggregation of oxygen vacancies could be another battery degradation mechanism accompanying lithiation induced phase changes.

36 MATERIALS SCIENCE↗
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 OSTI2023

In Situ Measurement of Buried Electrolyte–Electrode Interfaces for Solid State Batteries with Nanometer Level Precision

Many technologies including high-energy solid-state batteries rely on high quality solid–solid interfaces. Solid–solid interfaces are particularly difficult to study as their nature requires the interface to be buried. Here, in this work, we demonstrate the use of a combination of neutron reflectometry and in situ electrochemistry to measure the interface between Li metal and the solid electrolyte LiPON across an 8 cm 2 area. Neutron reflectometry measurements confirm the interphase to be less than 7 nm thick. The neutron reflectometry data further emphasize that the interphase that forms is a chemical gradient consisting of a Li-rich layer that gradually decreases in Li content until it blends into pure LiPON. Experimental confirmation that we can make ideal solid–solid interphases less than 10 nm thick will help facilitate the adoption of high efficiency next generation solid state batteries. Further this combination of complementary techniques provides a more general methodology for studying buried solid–solid interfaces across applications.

25 ENERGY STORAGE↗
DOE OSTI2025

Resistive Switching of Spinel Li 4 Ti 5 O 12 Lithium-Ion Battery Material for Neuromorphic Computing

The rapid rise of AI has exposed significant limitations in conventional Von Neumann computing architecture, particularly in regard to speed and energy efficiency. To address these challenges, researchers are exploring a brain-inspired neuromorphic architecture that mimics biological neural networks, enabling massive parallel processing with reduced power consumption for complex AI computational demands. Recent interest has focused on utilizing battery electrodes and solid electrolyte materials for their resistive switching properties in developing a neuromorphic architecture. These properties are precisely tuned through local- and bulk-level chemical composition modifications via voltage bias stimuli. In this study, we demonstrate fabricating a three-terminal lithium-ion electrochemical transistor based on lithium titanium oxide (Li 4 Ti 5 O 12 ), a popular lithium-ion battery anode material. We deposited and characterized LTO thin films using RF sputtering, demonstrating a 6 orders of magnitude increase in electronic conductivity upon lithiation, with conductivity plateauing after 20% lithiation. Density functional theory calculations revealed transformation from the insulating to conducting state, supported by experimental characterization through X-Ray Photoelectron Spectroscopy (XPS) and Direct Current (DC) polarization analyses. The fabricated transistor consisted of LTO as the channel layer, gold as source/drain terminals, lithium phosphorus oxynitride (LiPON) as the lithium-ion conductor, and copper as the gate terminal. The device exhibited clear hysteresis in transfer characteristics due to lithium insertion/extraction processes. Long-term potentiation (LTP) and long-term depression (LTD) measurements showed an asymmetric ratio of 1.425 and maximum/minimum conductance ratio of 7.83. When implemented in a deep neural network (DNN) for MNIST handwritten digit recognition, the device achieved 92.03% accuracy over 20 training epochs. Detailed transport mechanism analysis revealed the crucial role of oxygen vacancies and interface effects in device operation. Our preliminary findings establish LTO-based lithium-ion electrochemical transistors as promising candidates for energy-efficient neuromorphic computing applications, offering potential solutions to traditional Von Neumann architecture limitations.

25 ENERGY STORAGE↗
DOE OSTI2024

Uncovering the Network Modifier for Highly Disordered Amorphous Li‐Garnet Glass‐Ceramics

Abstract Highly disordered amorphous Li 7 La 3 Zr 2 O 12 (aLLZO) is a promising class of electrolyte separators and protective layers for hybrid or all‐solid‐state batteries due to its grain‐boundary‐free nature and wide electrochemical stability window. Unlike low‐entropy ionic glasses such as Li x PO y N z (LiPON), these medium‐entropy non‐Zachariasen aLLZO phases offer a higher number of stable structure arrangements over a wide range of tunable synthesis temperatures, providing the potential to tune the LBU‐Li + transport relation. It is revealed that lanthanum is the active “network modifier” for this new class of highly disordered Li + conductors, whereas zirconium and lithium serve as “network formers”. Specifically, within the solubility limit of La in aLLZO, increasing the La concentration can result in longer bond distances between the first nearest neighbors of Zr─O and La─O within the same local building unit (LBU) and the second nearest neighbors of Zr─La across two adjacent network‐former and network‐modifier LBUs, suggesting a more disordered medium‐ and long‐range order structure in LLZO. These findings open new avenues for future designs of amorphous Li + electrolytes and the selection of network‐modifier dopants. Moreover, the wide yet relatively low synthesis temperatures of these glass‐ceramics make them attractive candidates for low‐cost and more sustainable hybrid‐ or all‐solid‐state batteries for energy storage.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Manganese‐Based Spinel Cathodes: A Promising Frontier for Solid‐State Lithium‐Ion Batteries

Recently, all-solid-state lithium-ion batteries (ASSLIBs), which exhibit improved safety and enhanced energy density compared to conventional commercialized lithium-ion batteries (LIBs), thereby have garnered extensive research interest. Among the promising cathode candidates, Mn-based spinel cathodes LiMn 2 O 4 (LMO) and LiNi 0.5 Mn 1.5 O 4 (LNMO), with the unique characteristics of low cost, structural stability, and 3D Li-ion diffusion channels, have demonstrated excellent performance in LIBs and presented great potential in ASSLIBs applications. However, several challenges, including structural degradations, poor interfacial contact, large interfacial resistance, and Mn-dissolution/diffusion during the electrochemical cycling, hinder their practical applications and commercialization in the ASSLIBs. Particularly, the high-voltage LNMO cathodes suffer from the challenge of electrochemical incompatibility with most of the solid-state electrolytes (SSEs). Herein, the spinel structure, the electrochemical behavior, and the structural degradation of the LMO/LNMO are explored. The characteristics and recent progress of the mitigating strategies to the challenges of various SSEs, including polymer-, oxide-, composite-, sulfide-, halide-, and LiPON-based SSEs, are introduced when paired with LMO/LNMO. Finally, the directions for future research to advance Mn-based spinel cathodes and fulfill the requirements of the next-generation ASSLIBs are also discussed.

Dou, Yu [Concordia University, Montreal, QC (Canad↗
DOE OSTI2022

Porosity Development at Li-Rich Layered Cathodes in All-Solid-State Battery during In Situ Delithiation

Structural evolutions are crucial for determining the performance of high-voltage lithium, manganese-rich layered cathodes. Moreover, interface between electrode and electrolyte plays a critical role in governing ionic transfer in all-solid-state batteries. In this work, we unveil two different types of porous structure in Li 1.2 Ni 0.2 Mn 0.6 O 2 cathode with LiPON solid-state electrolyte. Na-nopores are found near the cathode/electrolyte interface at pristine state, where cation mixing, phase transformation, oxygen loss and Mn reduction are also found. In situ Li + extraction induces the evolution of nanovoids, initially formed near the inter-face then propagated into the bulk. Despite the development of nanovoids, layered structure is conserved, suggesting the nature of nanopores and nanovoids are different and their impact would be divergent. This work demonstrates the intrinsic interfacial layer, as well as the dynamic scenario of nanovoid formation inside high-capacity layered cathode, which help understanding the performance fading in cathodes and offer insights into the all-solid-state battery design.

25 ENERGY STORAGE↗
DOE OSTI2023

Stable Supercapacity of Binder-Free TiO 2 (B) Epitaxial Electrodes for All-Solid-State Nanobatteries

Owing to its pseudocapacitive, unidimensional, rapid ion channels, TiO 2 (B) is a promising material for application to battery electrodes. In this study, we align these channels by epitaxially growing TiO 2 (B) films with the assistance of an isostructural VO 2 (B) template layer. In a liquid electrolyte, binder-free TiO 2 (B) epitaxial electrodes exhibit a supercapacity near the theoretical value of 335 mA h g –1 and an excellent charge–discharge reproducibility for ≥200 cycles, which outperform those of other TiO 2 (B) nanostructures. For the all-solid-state configuration employing the LiPON solid electrolyte, excellent stability persists. Our findings suggest excellent potential for miniaturizing all-solid-state nanobatteries in self-powered integrated circuits.

25 ENERGY STORAGE↗
DOE OSTI2021

Spatially Resolved Potential and Li-Ion Distributions Reveal Performance-Limiting Regions in Solid-State Batteries

The performance of solid-state electrochemical systems is intimately tied to the potential and lithium distributions across electrolyte–electrode junctions that give rise to interface impedance. Here, we combine two operando methods, Kelvin probe force microscopy (KPFM) and neutron depth profiling (NDP), to identify the rate-limiting interface in operating Si-LiPON-LiCoO 2 solid-state batteries by mapping the contact potential difference (CPD) and the corresponding Li distributions. The contributions from ions, electrons, and interfaces are deconvolved by correlating the CPD profiles with Li-concentration profiles and by comparisons with first-principles-informed modeling. Furthermore, we find that the largest potential drop and variation in the Li concentration occur at the anode–electrolyte interface, with a smaller drop at the cathode–electrolyte interface and a shallow gradient within the bulk electrolyte. Correlating these results with electrochemical impedance spectroscopy following battery cycling at low and high rates confirms a long-standing conjecture linking large potential drops with a rate-limiting interfacial process.

25 ENERGY STORAGE↗
DOE OSTI2021

Recent progress and future prospects of atomic layer deposition to prepare/modify solid-state electrolytes and interfaces between electrodes for next-generation lithium batteries

Lithium ion batteries (LIBs) are encouraging electrochemical devices with remarkable properties including a high energy/power density, fast charging capability, and low self-discharge rate. Further increase in energy density as well as safe usage is needed for next-generation LIBs in electric transportation vehicles. Solid-state electrolytes (SSEs) are very promising for high-performance LIBs since they enable improved safety along with increased energy density compared to flammable liquid organic electrolytes. However, utilizing SSEs with a Li metal anode is very challenging due to the possibility of undesired side reactions and the formation of an unstable solid-electrolyte interphase. Therefore, it is critical to enhance the stability of SSEs against the Li anode. One feasible approach is to form a thin and conductive interlayer between the Li anode and solid-state electrolyte. Atomic layer deposition (ALD) is a unique technique for conformal coating of complex 3D structures with finely controlled film thickness (at the atomic scale). ALD coating on the surface of SSEs can be adopted for engineering solid-electrolyte interfaces with desired attributes and improved stability. In this review paper, we have discussed recent progress in implementing the ALD technique for depositing thin layers on various SSE configurations including lithium phosphorus oxynitride (LiPON), garnets, oxides, perovskites, sulphides, Li 3 BO 3 –Li 2 CO 3 (LBCO), and sodium super ionic conductors (NASICON). We have also highlighted the major areas for future research and development in the field. We believe that this review will be very helpful for directing future research on implementing ALD for synthesizing stable and high-performance SSEs with an engineered solid-electrolyte interface for next-generation electrochemical devices (e.g., Li-ion batteries, supercapacitors, and flow batteries).

36 MATERIALS SCIENCE↗
DOE OSTI2025

Interface diagnostics platform for thin-film solid-state batteries

Understanding the impedances of battery materials and their interfaces remains a major challenge, usually addressed by electrochemical impedance spectroscopy (EIS) where frequency-dependent complex impedance of full battery cells is measured and then modeled by a network of connected electrical elements. As conventionally applied, this approach produces ambiguity in that (1) multiple different network configurations may fit the data convincingly and (2) the method offers no direct association of the electrical elements with physical features of the battery. Here we present a new methodology that resolves both sources of ambiguity, enabled by expanding the experimental scope to directly inform the configuration of elements and their parameters in the network model. We demonstrate this methodology using thin film fabrication of solid state battery devices patterned by shadow masked sputter deposition, so that diagnostic devices corresponding to individual interface and material components can be fabricated simultaneously with full cell batteries. EIS models for the diagnostic devices can then be connected to form full cell networks whose topology matches the well-known physical configuration of the battery. When connected in this way, the full network model – made from connecting the diagnostic device EIS models – fits the full cell EIS data. For the case of a thin film solid state battery composed of amorphous silicon anode, lithium phosphorus oxynitride (LiPON) solid electrolyte, and lithium vanadium oxide (Li x V 2 O 5 ) cathode, we show that the approach allows us to identify ionic impedance/conductivity of the cathode/electrolyte as a limiting impedance and the anode/electrolyte interface cycling instability as a primary degradation factor.

25 ENERGY STORAGE↗
DOE OSTI2025

Thermal evaporation of thin Li films

Thermal evaporation of lithium is considered a promising technique for the fabrication of clean lithium thin films for solid-state batteries. Here, in this study, we present a practical investigation of nanometer scale lithium films prepared by evaporation on different substrates. These substrates include Li-alloying and nonalloying metals as well as different classes of solid-state lithium-ion conductors. The deposition rate was also varied. For films less than 100 nm thick, the data show that the deposition rate has the biggest impact on the surface coverage. At 50 Å/s, Li forms small particles <1 μm in diameter while higher deposition rate of 150 Å/s resulted in more uniform film morphology on all the substrates. At the lower deposition rates, the wetting of Li to the substrate will impact the particle morphology. We also used the particles to estimate a contact angle between Li and the substrate to qualitatively compare the adhesion from substrate to substrate. The smallest contact angle was observed from lithium films on Li 7 La 3 Zr 2 O 12 and LiPON (nominal Li 2.94 PO 3.5 N 0.31 ) solid-state electrolytes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Modeling the electrical double layer at solid-state electrochemical interfaces

Models of the electrical double layer (EDL) at electrode/liquid-electrolyte interfaces no longer hold for all-solid-state electrochemistry. Here we show a more general model for the EDL at a solid-state electrochemical interface based on the Poisson–Fermi–Dirac equation. By combining this model with density functional theory predictions, the interconnected electronic and ionic degrees of freedom in all-solid-state batteries, including the electronic band bending and defect concentration variation in the space-charge layer, are captured self-consistently. Along with a general mathematical solution, the EDL structure is presented in various materials that are thermodynamically stable in contact with a lithium metal anode: the solid electrolyte Li 7 La 3 Zr 2 O 12 (LLZO) and the solid interlayer materials LiF, Li 2 O and Li 2 CO 3 . Here, the model further allows design of the optimum interlayer thicknesses to minimize the electrostatic barrier for lithium ion transport at relevant solid-state battery interfaces.

25 ENERGY STORAGE↗