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At least 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Revisiting metal fluorides as lithium-ion battery cathodes

Metal fluorides, promising lithium-ion battery cathode materials, have been classified as conversion materials due to the reconstructive phase transitions widely presumed to occur upon lithiation. We challenge this view by studying FeF 3 using X-ray total scattering and electron diffraction techniques that measure structure over multiple length scales coupled with density functional theory calculations, and by revisiting prior experimental studies of FeF 2 and CuF 2 . Metal fluoride lithiation is instead dominated by diffusion-controlled displacement mechanisms, and a clear topological relationship between the metal fluoride F- sublattices and that of LiF is established. Initial lithiation of FeF3 forms FeF2 on the particle's surface, along with a cation-ordered and stacking-disordered phase, A-Li x Fe y F 3 , which is structurally related to alpha-/beta-LiMn 2+ Fe 3+ F 6 and which topotactically transforms to B- and then C-Li x Fe y F 3 , before forming LiF and Fe. Lithiation of FeF 2 and CuF 2 results in a buffer phase between FeF 2 /CuF 2 and LiF. Overall, the resulting principles will aid future developments of a wider range of isomorphic metal fluorides.

25 ENERGY STORAGE↗
DOE OSTI2021

Solid-state rigid-rod polymer composite electrolytes with nanocrystalline lithium ion pathways

A critical challenge for next-generation lithium-based batteries lies in development of electrolytes that enable thermal safety along with use of high-energy-density electrodes. We describe molecular ionic composite (MIC) electrolytes based on an aligned liquid crystalline polymer combined with ionic liquids and concentrated Li salt. This high strength (200 MPa) and non-flammable solid electrolyte possesses outstanding Li + conductivity (1 mS cm -1 at 25 °C) and electrochemical stability (5.6 V vs Li|Li + ) while suppressing dendrite growth and exhibiting low interfacial resistance (32 Ω cm 2 ) and overpotentials (≤ 120 mV @ 1 mA cm -2 ) during Li symmetric cell cycling. A heterogeneous salt doping process modifies a locally ordered polymer-ion assembly to incorporate an inter-grain network filled with defective LiFSI & LiBF 4 nanocrystals, strongly enhancing Li + conduction. Furthermore, this modular material fabrication platform shows promise for safe and high-energy-density energy storage and conversion applications, incorporating the fast transport of ceramic-like conductors with the superior flexibility of polymer electrolytes.

25 ENERGY STORAGE↗
DOE OSTI2013

Influence of cationic substitutions on the first charge and reversible capacities of lithium-rich layered oxide cathodes

The reversible capacity values of lithium-rich layered oxide cathodes depend on the length (capacity) of the plateau region during the first charge. With an aim to understand the factors that control the length of the plateau region and thereby enhance the reversible capacity, the effects of various cationic substitutions in Li 1.2 Mn 0.6 Ni 0.2 O 2 have been investigated systematically. Specifically, substitutions of (i) M 3+ = Al 3+ , Cr 3+ , Fe 3+ , Co 3+ , and Ga 3+ for equal amounts of Mn 4+ and Ni 2+ in Li 1.2 Mn 0.6-0.5x Ni 0.2-0.5x M x O 2 with x = 0.06, 0.13, and 0.2, (ii) Ti 4+ for Mn 4+ in Li 1.2 Mn 0.6-x Ti x Ni 0.2 O 2 with x = 0.025, 0.05, and 0.1, and (iii) Mg 2+ for Ni 2+ in Li 1.2 Mn 0.6 Ni 0.2-x Mg x O 2 with x = 0.025, 0.05, and 0.1 have been investigated. The cationic substitutions affect the first charge capacity values both in the sloping region corresponding to the oxidation of the transition-metal ions to the 4+ state and in the plateau region corresponding to the oxidation of O 2- ions to O 2 and/or transition-metal ions beyond 4+, which control the reversible capacity values in subsequent cycles. While the changes in the sloping-region capacity could be readily understood by considering the redox activities of the transition-metal ions, the plateau-region capacity is found to depend sensitively on the metal–oxygen covalence, which is dictated by the relative positions of the metal:3d band with respect to the top of the O 2- :2p band, and electron delocalization. For instance, an overlap of the Co 3+/4+ :t 2g band with the top of the O 2- :2p band along with a partially filled t 2g band across the shared octahedral edges makes the oxygen loss from the lattice and/or oxidation beyond 4+ much more facile.

solar (photovoltaic), phonons, energy storage (inc↗
DOE OSTI2015

Mitigating mechanical failure of crystalline silicon electrodes for lithium batteries by morphological design [Morphological design of silicon electrode with anisotropic interface reaction rate for lithium ion batteries]

Although crystalline silicon (c-Si) anodes promise very high energy densities in Li-ion batteries, their practical use is complicated by amorphization, large volume expansion and severe plastic deformation upon lithium insertion. Recent experiments have revealed the existence of a sharp interface between crystalline Si (c-Si) and the amorphous Li x Si alloy during lithiation, which propagates with a velocity that is orientation dependent; the resulting anisotropic swelling generates substantial strain concentrations that initiate cracks even in nanostructured Si. Here we describe a novel strategy to mitigate lithiation-induced fracture by using pristine c-Si structures with engineered anisometric morphologies that are deliberately designed to counteract the anisotropy in the crystalline/amorphous interface velocity. This produces a much more uniform volume expansion, significantly reducing strain concentration. Based on a new, validated methodology that improves previous models of anisotropic swelling of c-Si, we propose optimal morphological designs for c-Si pillars and particles. The advantages of the new morphologies are clearly demonstrated by mesoscale simulations and verified by experiments on engineered c-Si micropillars. The results of this study illustrate that morphological design is effective in improving the fracture resistance of micron-sized Si electrodes, which will facilitate their practical application in next-generation Li-ion batteries. In conclusion, the model and design approach present in this paper also have general implications for the study and mitigation of mechanical failure of electrode materials that undergo large anisotropic volume change upon ion insertion and extraction.

25 ENERGY STORAGE↗
DOE OSTI2021

Lithium vanadium oxide (Li 1.1 V 3 O 8 ) thick porous electrodes with high rate capacity: utilization and evolution upon extended cycling elucidated via operando energy dispersive X-ray diffraction and continuum simulation

The phase distribution of lithiated LVO in thick (~500 μm) porous electrodes (TPEs) designed to facilitate both ion and electron transport was determined using synchrotron-based operando energy dispersive X-ray diffraction (EDXRD). Probing 3 positions in the TPE while cycling at a 1C rate revealed a homogeneous phase transition across the thickness of the electrode at the 1st and 95th cycles. Additionally, continuum modelling indicated uniform lithiation across the TPE in agreement with the EDXRD results and ascribed decreasing accessible active material to be the cause of loss in delivered capacity between the 1st and 95th cycles. The model was supported by the observation of significant particle fracture by SEM consistent with loss of electrical contact. Overall, the combination of operando EDXRD, continuum modeling, and ex situ measurements enabled a deeper understanding of lithium vanadium oxide transport properties under high rate extended cycling within a thick highly porous electrode architecture.

25 ENERGY STORAGE↗
DOE OSTI2019

Computational evaluation of new lithium-3 garnets for lithium-ion battery applications as anodes, cathodes, and solid-state electrolytes

In this work, we explore a set of new garnet oxide structures that can be used as an anode, cathode or solid-electrolyte in lithium-ion batteries (LIBs) using high-throughput density functional theory. Specifically, we tested around 180 combinations of elemental substitutions for the dodecahedral X sites and octahedral Y sites in the Li 3 X 3 Y 2 O 12 type garnet structure and identified 19 stable (i.e., on the convex hull) and 11 nearly stable (i.e., within 50 meV/atom of the convex hull) Li 3 garnets with respect to decomposition to other stable phases in the Open Quantum Materials Database in the respective four-dimensional Li-X-Y -O chemical spaces. Our high-throughput screening strategy allows us to elucidate rules for garnet stability in terms of the ionic radii of the constituent elements. We evaluated the electrochemical window of these new, stable/nearly stable Li3-garnet compounds and classify each for potential applications as an anode, cathode, or solid-state electrolyte to be used in LIBs. Finally, Li + ion diffusivity is calculated for the representative Li 3 Nd 3 W 2 O 12 model system. The results we present here are expected to serve as a guideline for designing new garnet oxides for Li-ion battery applications.

25 ENERGY STORAGE↗
DOE OSTI2020

Temperature and processing effects on lithium ion conductivity of solution‐deposited lithium zirconium phosphate (LiZr 2 P 3 O 12 ) thin films

Abstract Lithium zirconium phosphate (LiZr 2 P 3 O 12 ) thin films have been prepared on platinized silicon substrates via a chemical solution deposition approach with processing temperatures between 700°C and 775°C. Films that were subject to a single high‐temperature anneal were found to crystallize at temperatures above 725°C. Crystallization was observed in films annealed after each deposited layer at 700°C and above. In both cases, grain size was found to increase with annealing temperature. Ion conductivity was found to increase with annealing temperature in singly annealed films. In per‐layer annealed films ion conductivity was found to initially increase then decrease with increasing annealing temperature. A maximum ion conductivity of 1.6 × 10 −6 S/cm was observed for the singly annealed 775°C condition, while a maximum ion conductivity of 5.8 × 10 −7 S/cm was observed for the 725°C per‐layer annealed condition. These results are consistent with an increasing influence of cross‐plane, internal interface resistance and vapor phase carrier loss in the per‐layer annealed samples. This work demonstrates that post‐deposition processing methods can strongly affect the ion conducting properties of LiZr 2 P 3 O 12 thin films.

Brummel, Ian A.↗
DOE OSTI2017

Transforming from planar to three-dimensional lithium with flowable interphase for solid lithium metal batteries

Solid-state lithium (Li) metal batteries are prominent among next-generation energy storage technologies due to their significantly high energy density and reduced safety risks. Previously, solid electrolytes have been intensively studied and several materials with high ionic conductivity have been identified. However, there are still at least three obstacles before making the Li metal foil-based solid-state systems viable, namely, high interfacial resistance at the Li/electrolyte interface, low areal capacity, and poor power output. The problems are addressed by incorporating a flowable interfacial layer and three-dimensional Li into the system. The flowable interfacial layer can accommodate the interfacial fluctuation and guarantee excellent adhesion at all time, whereas the three-dimensional Li significantly reduces the interfacial fluctuation from the whole electrode level (tens of micrometers) to local scale (submicrometer) and also decreases the effective current density for high-capacity and high-power operations. As a consequence, both symmetric and full-cell configurations can achieve greatly improved electrochemical performances in comparison to the conventional Li foil, which are among the best reported values in the literature. Noticeably, solid-state full cells paired with high–mass loading LiFePO4 exhibited, at 80°C, a satisfactory specific capacity even at a rate of 5 C (110 mA·hour g -1 ) and a capacity retention of 93.6% after 300 cycles at a current density of 3 mA cm -2 using a composite solid electrolyte middle layer. In addition, when a ceramic electrolyte middle layer was adopted, stable cycling with greatly improved capacity could even be realized at room temperature.

25 ENERGY STORAGE↗
DOE OSTI2013

Effects of Carbonate Solvents and Lithium Salts on Morphology and Coulombic Efficiency of Lithium Electrode

The application of lithium (Li) metal anode in rechargeable batteries is hindered by Li dendrite growth during Li deposition and low Li Coulombic efficiency (CE), where the nonaqueous electrolyte plays a critical role. In this work, the effects of different carbonate solvents and Li salts on Li deposition morphology and CE were systematically investigated. Typically cyclic carbonates are found to favor the formation of uniform Li film and improve Li CE than linear carbonates do. Several specific cyclic carbonates that are conventionally used as solid electrolyte interface formation additives in Li ion batteries can also improve the CE of Li anode. Furthermore, among the nine electrolyte salts studied, LiAsF6 and LiBOB lead to the highest CE for Li anode. LiBOB also leads to much smoother Li morphology than other salts do. Considering the better safety of LiBOB as compared to LiAsF6, LiBOB is a promising Li salt for rechargeable Li metal batteries with high CE. By combining the best electrolyte solvent/salt that can lead to high Li CE and novel electrolyte additives that can prevent dendrite formation, it is possible to find an electrolyte that not only prevents Li dendrite formation but also lead to high CE during Li deposition/stripping processes.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2017

Multifunctional structural lithium-ion battery for electric vehicles

An innovative concept for a multifunctional structural battery using lithium-ion battery materials as load bearing elements in a sandwich panel construction has been demonstrated. The structural battery prototype has exhibited an initial capacity of 17.85 Ah, an energy density of 248 Wh L −1 , a specific energy of 102 Wh kg −1 , and a capacity retention of 85.8% after 190 charge–discharge cycles at ~ C/3 rate and eight mechanical loading cycles (upto 1060 N). The mechanical stiffness in three-point bend tests follows expectations based on sandwich beam theory, proving that the battery materials are sharing in the load-carrying function of the sandwich panel. While areas for improvement of the fabrication and performance of the prototype still exist, the results of the current investigation demonstrate the promising potential of the proposed structural battery concept for the efficient use of space and mass in an electric vehicle.

Zhang, Yancheng↗
DOE OSTI2022

High-Safety Electrolytes for Lithium-Ion Batteries : Is non-flammability of electrolyte overrated in the overall safety performance of lithium ion batteries?

It has been widely considered that the flammability of the liquid electrolyte is one of the most influential factors that determine the safety of lithium ion batteries (LIBs). Following this consideration, a completely non-flammable electrolyte was designed and adopted to graphite||LiFePO 4 (Gr||LFP) batteries. Contrary to the conventional understanding, the completely non-flammable electrolyte with phosphorus-containing solvents exhibits inferior safety performance in commercial Gr||LFP batteries, in comparison to the flammable conventional LiPF 6 -organocarbonate electrolyte. Mechanistic studies identify the exothermic reactions between the electrolyte (especially the flame retarding phosphate solvent) and the charged electrodes as the “culprit” behind such a counterintuitive phenomenon. The discovery emphasizes the importance of reducing the electrolyte reactivity when designing safe electrolytes, as well as the necessity of evaluating safety performances of electrolyte on a battery level.

25 ENERGY STORAGE↗
DOE OSTI2024

Development of Thin, Robust, Lithium-Impenetrable, HighConductivity, Electrochemically Stable, Scalable, and Low-Cost Glassy Solid Electrolytes for Solid State Lithium Batteries (Final Report)

Solid-state electrolytes (SSEs) must have thicknesses of < 50 microns in order to be competitive with current state-of-the-art organic liquid electrolyte batteries. Mixed oxy-sulfide-nitride (MOSN) glassy solid electrolytes (GSEs) can be drawn into thin ribbons using the glass redraw process, to form glasses with superior performance in a safe, lower-cost, monolithic glass film. It is expected that these new GSEs in solid-state lithium batteries (SSLBs) increase the energy density (anode basis) from ~300 mAh/g to ~ 4000 mAh/g. This project is focused on the development of candidate MOS GSE compositions, and optimization of the thin film drawing process to generate thin film glass ribbons for use in SSLBs.

25 ENERGY STORAGE↗
DOE OSTI2026

ICL Commercial Production of Lithium Iron Phosphate Cathode Powder for the Global Lithium Battery Industry Final Technical Report

ICL was investing in producing cathode active material, Lithium Iron Phosphate (LFP), used in the production of batteries for both electric vehicles and stationary storage. The demand for LFP was increasing with the global focus on sustainable energy, and there was no current manufacturer of this material in the United States. As such, imported LFP is subject to the uncertainties around supply chain and control of a foreign supplier. This investment would have allowed ICL to be a United States leader in LFP production. To gain a position in this market, ICL licensed the technology from a firm that has the process technology and has reliably supplied LFP into the battery market and currently has customers purchasing their product.

25 ENERGY STORAGE↗
DOE OSTI2018

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of lithium-ion (Li-ion) batteries. However, a number of setbacks prevent their integration into commercial devices. The main limiting factor is due to nanoscale phenomena occurring at the electrode/electrolyte interfaces, ultimately leading to degradation of battery operation. These key problems are highly challenging to observe and characterize as these batteries contain multiple buried interfaces. One approach for direct observation of interfacial phenomena in thin film batteries is through the fabrication of electrochemically active nanobatteries by a focused ion beam (FIB). As such, a reliable technique to fabricate nanobatteries was developed and demonstrated in recent work. Herein, a detailed protocol with a step-by-step process is presented to enable the reproduction of this nanobattery fabrication process. In particular, this technique was applied to a thin film battery consisting of LiCoO 2 /LiPON/a-Si, and has further been previously demonstrated by in situ cycling within a transmission electron microscope.

25 ENERGY STORAGE↗