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

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At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

High-Throughput Exploration of Lithium-Alloy Protection Layers for High-Performance Lithium-Metal Batteries

To realize high specific capacity Li-metal batteries, a protection layer for the Li-metal anode is needed. We are carrying out combinatorial screening of Li-alloy thin films as the protection layer which can undergo significant lithiation with minimum change in volume and crystal structure. In this paper, we have fabricated lithium-free binary alloy thin film composition spreads of Co 1–x Sn x on Cu layers on Si substrates. The crystallinity of the thin films was tuned by varying the deposition temperature followed by electrochemical lithiation to form Li-alloy ternary thin films. Synchrotron diffraction is used as the main tool to investigate the crystallinity of the films before and after lithiation. Co 3 Sn 2 alloy thin films are found to exhibit significant lithium uptake capacity while maintaining its structural integrity, and are thus a good candidate of the Li-metal protection layer.

25 ENERGY STORAGE↗
DOE OSTI2022

Asphericity Can Cause Nonuniform Lithium Intercalation in Battery Active Particles

Uniform intercalation is desired to enable next-generation Li-ion batteries. While we expect nonuniformity in materials undergoing a phase change, single-phase intercalation materials such as nickel manganese cobalt oxide are believed to lithiate uniformly at the particle/electrolyte interface. However, recent imaging reveals nonuniform lithiation. Motivated by this discrepancy, we examine if aspherical particle shape can cause such nonuniformity since the conventional belief is based on spherical particle theory. We obtain real particle geometries using rapid lab-based X-ray computed tomography and subsequently perform physics-based calculations accounting for electrochemical reactions at the particle/electrolyte interface and lithium transport inside the particle bulk. The aspherical geometry breaks the symmetry and causes nonuniform reaction distribution. Such nonuniformity is exacerbated as the particle becomes more aspherical. We report the proposed mechanism represents a fundamental limit on achievable lithiation uniformity in aspherical particles in the absence of other mechanisms causing inhomogeneity, such as grain structure, nonuniform carbon-binder coating, etc.

25 ENERGY STORAGE↗
DOE OSTI2018

Detrimental Effects of Chemical Crossover from the Lithium Anode to Cathode in Rechargeable Lithium Metal Batteries

The interfacial stability is one of the crucial factors affecting long-term cyclability of lithium (Li) metal batteries (LMBs). While cross contamination (such as Mn+2 crossover from cathode to contaminate graphite anode) phenomena has been well studied in Li ion batteries (LIBs), the similar phenomena has rarely been studied in LMBs. Here, we systematically investigated the cathode failure triggered by the chemical crossover between the electrode pair in rechargeable LMBs. In strong contrast to LIBs, the cathode in LMBs suffers more significant and irreversible capacity fade during cycling and its capacity cannot be fully recovered even when Li metal anode has been replaced in the successive cycling. In-depth characterizations of the cathode surface reveal severe CEI deterioration related to the accumulation of highly resistive polymeric components and lithium fluoride. The soluble decomposition products generated by extensive salt-anion decomposition at Li metal surface can diffuse toward cathode side and result in severe deterioration of cathode as well asseparator surfaces. A polydopamine coated separator with selective Li-ion permeability has been developed to mitigate the detrimental chemical crossover and enhance the cathode stability.

Lee, Hongkyung↗
DOE OSTI2020

Improving Lithium Metal Composite Anodes with Seeding and Pillaring Effects of Silicon Nanoparticles

Metallic lithium (Li) anodes are crucial for the development of high specific energy batteries yet plagued by their poor cycling efficiency. Electrode architecture engineering is vital for maintaining a stable anode volume and suppress Li corrosion during cycling. In this paper, a reduced graphene oxide “host” framework for Li metal anodes is further optimized by embedding silicon (Si) nanoparticles between the graphene layers. They serve as Li nucleation seeds to promote Li deposition within the framework even without pre-stored Li. Meanwhile, the LixSi alloy particles serve as supporting “pillars” between the graphene layers, enabling a minimized thickness shrinkage after full stripping of metallic Li. Combined with a Li compatible electrolyte, 99.4% Coulombic efficiency over ~600 cycles is achieved, and stable cycling of a Li||NMC532 full cell for ~380 cycles with negligible capacity decay is realized.

Wang, Hansen↗
DOE OSTI2017

Electrolyte additive enabled fast charging and stable cycling lithium metal batteries

Batteries using lithium (Li) metal as anodes are considered promising energy storage systems because of their high energy densities. However, safety concerns associated with dendrite growth along with limited cycle life, especially at high charge current densities, hinder their practical uses. Here we report that an optimal amount (0.05 M) of LiPF6 as an additive in LiTFSI-LiBOB dual-salt/carbonate-solvent-based electrolytes significantly enhances the charging capability and cycling stability of Li metal batteries. In a Li metal battery using a 4-V Li-ion cathode at a moderately high loading of 1.75mAh cm(-2), a cyclability of 97.1% capacity retention after 500 cycles along with very limited increase in electrode overpotential is accomplished at a charge/discharge current density up to 1.75 mA cm(-2). The fast charging and stable cycling performances are ascribed to the generation of a robust and conductive solid electrolyte interphase at the Li metal surface and stabilization of the Al cathode current collector.

25 ENERGY STORAGE↗
DOE OSTI2022

Spectral control of nonclassical light pulses using an integrated thin-film lithium niobate modulator

Abstract Manipulating the frequency and bandwidth of nonclassical light is essential for implementing frequency-encoded/multiplexed quantum computation, communication, and networking protocols, and for bridging spectral mismatch among various quantum systems. However, quantum spectral control requires a strong nonlinearity mediated by light, microwave, or acoustics, which is challenging to realize with high efficiency, low noise, and on an integrated chip. Here, we demonstrate both frequency shifting and bandwidth compression of heralded single-photon pulses using an integrated thin-film lithium niobate (TFLN) phase modulator. We achieve record-high electro-optic frequency shearing of telecom single photons over terahertz range (±641 GHz or ±5.2 nm), enabling high visibility quantum interference between frequency-nondegenerate photon pairs. We further operate the modulator as a time lens and demonstrate over eighteen-fold (6.55 nm to 0.35 nm) bandwidth compression of single photons. Our results showcase the viability and promise of on-chip quantum spectral control for scalable photonic quantum information processing.

Optics↗
DOE OSTI2019

Fast lithium growth and short circuit induced by localized-temperature hotspots in lithium batteries

Fast-charging and high-energy-density batteries pose significant safety concerns due to high rates of heat generation. Understanding how localized high temperatures affect the battery is critical but remains challenging, mainly due to the difficulty of probing battery internal temperature with high spatial resolution. Here we introduce a method to induce and sense localized high temperature inside a lithium battery using micro-Raman spectroscopy. We discover that temperature hotspots can induce significant lithium metal growth as compared to the surrounding lower temperature area due to the locally enhanced surface exchange current density. More importantly, localized high temperature can be one of the factors to cause battery internal shorting, which further elevates the temperature and increases the risk of thermal runaway. This work provides important insights on the effects of heterogeneous temperatures within batteries and aids the development of safer batteries, thermal management schemes, and diagnostic tools.

25 ENERGY STORAGE↗
DOE OSTI2018

Approaching the capacity limit of lithium cobalt oxide in lithium ion batteries via lanthanum and aluminium doping

Here, lithium cobalt oxides (LiCoO 2 ) possess a high theoretical specific capacity of 274 mAh/g. However, cycling LiCoO 2 -based batteries to voltages greater than 4.35 V vs. Li/Li + causes significant structural instability and severe capacity fade. Consequently, commercial LiCoO 2 exhibits a maximum capacity of only ~165 mAh/g. Here we develop a doping technique to tackle this long-standing issue of instability and thus increase the capacity of LiCoO 2 . La and Al are concurrently doped into Co-containing precursors, followed by high-temperature calcination with lithium carbonate. The dopants are found to reside in the crystal lattice of LiCoO 2 , where La works as a pillar to increase the c-axis distance and Al as a positively charged center, facilitating Li + diffusion, stabilizing the structure and suppressing the phase transition during cycling, even at a high cut-off voltage of 4.5 V. This doped LiCoO 2 displays an exceptionally high capacity of 190 mAh/g, cyclability with 96% capacity retention over 50 cycles and significantly enhanced rate capability.

25 ENERGY STORAGE↗
DOE OSTI2023

A free-standing lithium phosphorus oxynitride thin film electrolyte promotes uniformly dense lithium metal deposition with no external pressure

Lithium phosphorus oxynitride (LiPON) is an amorphous solid electrolyte that has been extensively studied over the last three decades. Despite the promise of pairing it with various electrode materials, LiPON’s rigidity and air sensitivity set limitations to understanding its intrinsic properties. We report a methodology to synthesize LiPON in a free-standing form that manifests remarkable flexibility and a Young’s modulus of ∼33 GPa. We use solid-state nuclear magnetic resonance and differential scanning calorimetry to quantitatively reveal the chemistry of the Li/LiPON interface and the presence of a well-defined LiPON glass-transition temperature of 207 °C. Combining interfacial stress and a gold seeding layer, our free-standing LiPON shows a uniformly dense deposition of lithium metal without the aid of external pressure. This free-standing LiPON film offers opportunities to study fundamental properties of LiPON for interface engineering for solid-state batteries.

25 ENERGY STORAGE↗
DOE OSTI2013

Correlating cation ordering and voltage fade in a lithium–manganese-rich lithium-ion battery cathode oxide: a joint magnetic susceptibility and TEM study

Structure–electrochemical property correlation is presented for lithium–manganese-rich layered–layered nickel manganese cobalt oxide (LMR–NMC) having composition Li1.2Co0.1Mn0.55Ni0.15O2 (TODA HE5050) in order to examine the possible reasons for voltage fade during short-to-mid-term electrochemical cycling. The Li1.2Co0.1Mn0.55Ni0.15O2 based cathodes were cycled at two different upper cutoff voltages (UCV), 4.2 V and 4.8 V, for 1, 10, and 125 cycles; voltage fade was observed after 10 and 125 cycles only when the UCV was 4.8 V. Magnetic susceptibility and selected-area electron diffraction data showed the presence of cation ordering in the pristine material, which remained after 125 cycles when the UCV was 4.2 V. When cycled at 4.8 V, the magnetic susceptibility results showed the suppression of cation ordering after one cycle; the cation ordering diminished upon further cycling and was not observed after 125 cycles. Selected-area electron diffraction data from oxides oriented towards the [0001] zone axis revealed a decrease in the intensity of cation-ordering reflections after one cycle and an introduction of spinel-type reflections after 10 cycles at 4.8 V; after 125 cycles, only the spinel-type reflections and the fundamental O3 layered oxide reflections were observed. A significant decrease in the effective magnetic moment of the compound after one cycle at 4.8 V indicated the presence of lithium and/or oxygen vacancies; analysis showed a reduction of Mn4+ (high spin/low spin) in the pristine oxide to Mn3+ (low spin) after one cycle. The effective magnetic moment was higher after 10 and 125 cycles at 4.8 V, suggesting the presence of Mn3+ in a high spin state, which is believed to originate from distorted spinel (Li2Mn2O4) and/or spinel (LiMn2O4) compounds. The increase in effective magnetic moments was not observed when the oxide was cycled at 4.2 V, indicating the stability of the structure under these conditions. This study shows that structural rearrangements in the LMR–NMC oxide happen only at higher potentials (4.8 V, for example) and provides evidence of a direct correlation between cation ordering and voltage fade.

Mohanty, Debasish↗
DOE OSTI2013

Investigating phase transformation in the Li1.2Co0.1Mn0.55Ni0.15O2 lithium-ion battery cathode during high-voltage hold (4.5 V) via magnetic, X-ray diffraction and electron microscopy studies

This study is the first that provides evidence of phase transformation in a Li-rich Li1.2Co0.1Mn0.55Ni0.15O2 cathode material for lithium-ion batteries (LIBs) during constant voltage charging. Diffraction and magnetic measurement techniques were successfully implemented to investigate the structural transformation in this cathode material during holding a half-cell at 4.5 V in a charged state. The results from X-ray diffraction showed a decrease in c-lattice parameters during high-voltage hold. Magnetic data revealed an increase in average effective magnetic moments of transition metal (TM) ions at constant voltage corresponding to a change in electronic states of TM ions. Analysis showed the reduction of Ni4+ to Ni2+, which was attributed to charge compensation due to oxygen loss. The appearance of the strong {100} forbidden reflection in the single-crystal selected area electron diffraction (SAED) data was attributed to migration of transition metal ions to the octahedral vacancy sites in the lithium layer during high-voltage hold, which was in agreement with the magnetization results. After prolonged hold at 4.5 V, high-resolution transmission electron microscopy (TEM) images along with SAED results showed the presence of spinel phases in the particles, indicating a layered to spinel like phase transformation at constant voltage in agreement with the magnetic data. The results obtained from these magnetic and diffraction studies furnish the fundamental understanding of the structural transformation pathways in Li-rich cathodes at constant voltage and will be instrumental for modifying the parent structure to achieve greater stability.

Mohanty, Debasish↗