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Results for “anode solid electrolyte interphase”

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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Impact of dual-layer solid-electrolyte interphase inhomogeneities on early-stage defect formation in Si electrodes

While intensive efforts have been devoted to studying the nature of the solid-electrolyte interphase (SEI), little attention has been paid to understanding its role in the mechanical failures of electrodes. Here we unveil the impact of SEI inhomogeneities on early-stage defect formation in Si electrodes. Buried under the SEI, these early-stage defects are inaccessible by most surface-probing techniques. With operando full field diffraction X-ray microscopy, we observe the formation of these defects in real time and connect their origin to a heterogeneous degree of lithiation. This heterogeneous lithiation is further correlated to inhomogeneities in topography and lithium-ion mobility in both the inner- and outer-SEI, thanks to a combination of operando atomic force microscopy, electrochemical strain microscopy and sputter-etched X-ray photoelectron spectroscopy. Our multi-modal study bridges observations across the multi-level interfaces (Si/LixSi/inner-SEI/outer-SEI), thus offering novel insights into the impact of SEI homogeneities on the structural stability of Si-based lithium-ion batteries. Severe structural deformation during (de)lithiation is the main factor limiting the stability of Si anodes in Li-ion batteries. Here, a multi-modal approach is used to visualize these deformations in their early-stage and link them to inhomogeneities in the dual-layer solid-electrolyte interphase.

25 ENERGY STORAGE↗
DOE OSTI2020

High-Power Lithium Metal Batteries Enabled by High-Concentration Acetonitrile-Based Electrolytes with Vinylene Carbonate Additive

To enable next-generation high power, high-energy-density lithium (Li) metal batteries (LMBs), an electrolyte possessing both high Li Coulombic efficiency (CE) at high-rate and good anodic stability on cathodes is critical. Acetonitrile (AN) is a well-known organic solvent for high anodic stability and high ionic conductivity, yet its application in LMBs is limited due to its poor compatibility with Li metal anode even at high salt concentration conditions. Here, we developed a highly concentrated AN-based electrolyte with vinylene carbonate (VC) additive to suppress Li+ depletion at high current densities. Addition of VC in the AN-based electrolyte leads to the formation of a polycarbonate-based solid electrolyte interphase which minimizes Li corrosion and leads to very high Li CE of up to 99.1% at a current density of 0.2 mA cm-2. Using such an electrolyte, fast charging of Li||NMC333 cells has been realized at a high current density of 3.6 mA cm-2, and stable cycling of Li||NMC622 cells with a high cathode loading of 4 mAh cm-2 has also been demonstrated.

Peng, Zhe↗
DOE OSTI2025

Reactivity of Carbonate Solvent Electrolytes on Lithium Silicon Anodes

Silicon (Si) is promising for lithium-ion battery (LIB) anodes due to their high theoretical capacity and low electrochemical potential. However, significant challenges remain, including severe volumetric expansion during cycling and the electrochemical instability of electrolytes, which leads to the formation of a nonuniform solid electrolyte interphase (SEI). To investigate SEI formation mechanisms, computational molecular dynamics simulations offer valuable insights. In this work, we examine the trajectories and charge transfer behavior of lithium hexafluorophosphate (LiPF 6 ) salt with various solvent compositions using density functional theory (DFT) and ab initio molecular dynamics (AIMD). Among the tested electrolyte systems, LiPF 6 with vinylene carbonate (VC) added to ethyl methyl carbonate (EMC) exhibits the lowest reactivity with the Si anode. In contrast, the effects of fluoroethylene carbonate (FEC) and VC depend on whether the primary solvent is EMC alone or a mixture of ethylene carbonate (EC) and EMC. Moreover, we show that electrolyte reactivity varies with the degree of lithiation of the Si anode (LiSi vs Li 15 Si 4 ) and under different charge states. To decouple electrolyte reactivity from surface effects, we analyze the dissociation and formation energies of individual species from solvated configurations. Overall, these first-principles-based findings provide a strategic foundation for electrolyte design to improve cycling stability and extend calendar life in LIBs using Si anodes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

In Situ Formation of Li 3 P Layer Enables Fast Li + Conduction across Li/Solid Polymer Electrolyte Interface

Abstract Solid‐state polymer electrolytes provide better flexibility and electrode contact than their ceramic counterparts, making them a worthwhile pursuit for all‐solid‐state lithium‐metal batteries. However, their large Li/solid state electrolyte interfacial resistance, small critical current density, and rapid lithium dendrite growth during cycling still limit their viability. Owing to these restrictions, all‐solid‐state cells with solid polymer electrolytes must be cycled above room‐temperature and with a small current density. These problems can be mitigated with an in situ formed artificial solid electrolyte interphase that rapidly conducts Li + ions. Herein, a Li 3 P layer formed in situ at the Li‐metal/solid polymer electrolyte interphase is reported that significantly reduces the electrode/electrolyte interfacial resistance. Additionally, this layer increases the wettability of the solid polymer by the metallic lithium anode, allowing for the critical current density of lithium symmetric cells to be doubled by homogenizing the current density at the interface. All‐solid‐state Li/Li symmetric cells and Li/LiFePO 4 cells with the Li 3 P layer show improved cycling performance with a high current density.

Wu, Nan↗
DOE OSTI2020

Electrode roughness dependent electrodeposition of sodium at the nanoscale

Na metal is an attractive anode material for rechargeable Na ion batteries, however, the dendritic growth of Na can cause serious safety issues. Along with modifications of solid-electrolyte interphase (SEI), engineering the electrode has been reported to be effective in suppressing Na dendritic growth, likely by reducing localized current density accumulation. However, fundamental understanding of Na growth at the nanoscale is still limited. Here, we report an in-situ study of Na electrodeposition in electrochemical liquid cells with the electrodes in different surface roughness, e.g., flat or sharp curvature. Real time observation using transmission electron microscopy (TEM) reveals the Na electrodeposition with remarkable details. Relatively large Na grains (in the micrometer scale) are achieved on the flat electrode surface. The local SEI thickness variations impact the growth rate, thus the morphology of individual grains. In contrast, small Na grains (in tens of nanometers) grow explosively on the electrode at the point with sharp curvature. The newly formed Na grains preferentially deposit at the base of existing grains close to the electrode. Further studies using continuum-based computational modeling suggest that the growth mode of an alkali metal (e.g. Na) is strongly influenced by the transport properties of SEI. Our direct observation of Na deposition in combination with the theoretical modeling provides insights for comprehensive understanding of electrode roughness and SEI effects on Na electrochemical deposition.

25 ENERGY STORAGE↗
DOE OSTI2023

Conjugated Imine Polymer Synthesized via Step‐Growth Metathesis for Highly Stable Silicon Nanoparticle Anodes in Lithium‐Ion Batteries

Abstract This work reports a new method to synthesize polyphenylmethanimine (polyPMI) as a linear or a hyperbranched, conjugated polymer using an aldehyde‐imine metathesis reaction. This work details the reaction mechanisms of this polymerization by characterizing a red‐shift in its absorption spectrum as polymer conjugation length increases and verifies that this optical shift results from extended π‐condensation using density functional theory. This new synthetic approach provides a polymer that can potentially be depolymerized for facile recyclability and is compatible with air‐ and water‐sensitive chemistries. As an example of the utility of this new approach, this work demonstrates that this polymer can be directly grown on silicon nanoparticles to create silicon anodes for lithium‐ion batteries with a high degree of electrochemical interfacial passivation. These silicon anodes exhibit Coulombic efficiencies above 99.9% and can accommodate silicon nanoparticle expansion and contraction during lithiation and delithiation as demonstrated by stable reversible capacities for 500 cycles. Finally, this work demonstrates that polyPMI facilitates the formation of a lithium fluoride rich solid electrolyte interphase that remains chemically and mechanically stable after long term cycling.

25 ENERGY STORAGE↗
DOE OSTI2019

An ultrathin ionomer interphase for high efficiency lithium anode in carbonate based electrolyte

High coulombic efficiency and dendrite suppression in carbonate electrolytes remain challenges to the development of high-energy lithium ion batteries containing lithium metal anodes. Here we demonstrate an ultrathin (≤100 nm) lithium-ion ionomer membrane consisting of lithium-exchanged sulfonated polyether ether ketone embedded with polyhedral oligosilsesquioxane as a coating layer on copper or lithium for achieving efficient and stable lithium plating-stripping cycles in a carbonate-based electrolyte. Operando analyses and theoretical simulation reveal the remarkable ability of the ionomer coating to enable electric field homogenization over a considerably large lithium-plating surface. The membrane coating, serving as an artificial solid-electrolyte interphase filter in minimizing parasitic reactions at the electrolyte-electrode interface, enables dendrite-free lithium plating on copper with outstanding coulombic efficiencies at room and elevated (50 °C) temperatures. The membrane coated copper demonstrates itself as a promising current collector for manufacturing high-quality pre-plated lithium thin-film anode.

25 ENERGY STORAGE↗
DOE OSTI2021

Chemical Interplay of Silicon and Graphite in a Composite Electrode in SEI Formation

In this study, we investigated the effect of the Si/graphite weight ratio in half-cells on the solid electrolyte interphase (SEI) layer's chemistry. The nominal concentrations of active materials were (wt % Si/wt % Gr) 15/73, 30/58, 60/28, and 80/0. The electrolyte in the cells consisted of either 1.2 M LiPF 6 in ethylene carbonate/ethyl methyl carbonate (3:7 by wt) or 1.2 M LiPF 6 in ethylene carbonate:ethyl methyl carbonate (3:7 by wt) + 10 wt % fluoroethylene carbonate. These coin cells were cycled five times at the C/10 rate. As expected, the addition of silicon to the electrode significantly increased the measured capacity. Examination of the aged composite material showed that the electrolyte influenced the concentration of chemical environments on the surface. Depth profiling revealed that these concentrations of surface environments changed with sputtering time. A statistics-of-mixtures model was used to deconvolute how silicon and graphite interacted during the formation of these species and how the interaction changed with depth.

25 ENERGY STORAGE↗
DOE OSTI2020

SiO 2 Is Wasted Space in Single-Nanometer-Scale Silicon Nanoparticle-Based Composite Anodes for Li-Ion Electrochemical Energy Storage

The electrode processing conditions of silicon-based composite anodes play a pivotal role in the resulting interfacial chemical speciation and, thus, the electrochemical cycling behavior of the electrode. Systematically investigating how small chemical changes to the surface of the silicon nanoparticle (NP) affect larger, electrode-level properties is a strategy that will inform design principles to maximize electrode energy density and extend electrode lifetime. Here, we incorporate silicon nanoparticles (NPs) with an average diameter of 5.5 nm synthesized from the gas phase through a nonthermal plasma method into composite anode half-cell coin cells. We perform chemistry to functionalize the native hydride-terminated silicon NP surface with N-methylpyrrolidone (NMP) to improve slurry properties and reduce the silicon reactivity prior to composite electrode fabrication. We construct composite electrodes from these silicon NPs and observe an 86% capacity retention over 100 cycles at a rate of C/5, with an initial silicon specific capacity of 2600 mAh/g. We expose the same Si NPs to water that completely oxidizes these small-diameter NPs to SiO 2 and find that the SiO 2 NPs in the same electrode configuration exhibit no obvious lithium alloying capacity in the electrochemical potential range of lithium silicide alloy formation. As this result stands in contrast to existing literature, we provide a discussion on the origin of the discrepancies.

25 ENERGY STORAGE↗
DOE OSTI2020

Electrolyte design for Li metal-free Li batteries

Li metal, with the lowest thermodynamically achievable negative electrochemical potential and the highest specific capacity (3860 mAh g -1 ), is the ultimate anode choice for Li batteries. However, the highest reported Li plating/stripping Coulombic efficiency (CE) of 99.5% after extensive efforts is still too low for the Li metal-free (all the Li metal in cycling comes from cathode, without anode pre-lithiation) Li metal batteries. The low CE is attributed to both non-uniform Li plating/stripping on the lithiophobic Cu current collector and Li dendrite growth through lithiophilic organic–inorganic solid electrolyte interphase (SEI) formed in carbonate electrolytes. Here, we use a lithiophilic Bismuth graphite blend (Bi–Gr) substrate to replace lithiophobic Cu current collector to seed a uniform Li nucleation, and form a lithiophobic LiF-rich SEI rather than lithiophilic organic-rich SEI to suppress Li dendrite growth. Molecular dynamics simulations reveal the preferential reduction of anions in 2.0 M LiPF 6 in tetrahydrofuran/2-methyl tetrahydrofuran (2.0 M LiPF 6 –mixTHF) electrolyte to generate LiF-rich SEI on plated Li. Bi–Gr substrate and 2.0 M LiPF 6 –mixTHF electrolyte enable the Li anodes to achieve a record high CE of 99.83% at a high capacity of 1.0 mAh cm -2 and current of 0.5 mA cm -2 . The Bi particles serve as dispersed nucleation centers that promote uniform Li deposition with strong adhesion to the substrate to avoid dead Li, while the lithiophobic LiF-rich SEI promotes lateral Li growth and suppresses the vertical Li dendrite growth even at a high current density of 3.0 mA cm -2 and high areal capacities of 3.0 mAh cm -2 . The regulation of Li nucleation and growth enables the Li metal-free LiFePO 4 full cells to achieve 100 cycles at a practical areal capacity of >2.0 mAh cm -2 . This article highlights the benefits of simultaneous substrate design to improve Li nucleation and electrolyte design to promote lithiophobic SEI growth, enabling a promising and practical route Li metal-free Li metal batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Superior metal storage behavior of Zn-containing porous carbon nanostructures for Na and Li metal batteries

Na and Li metals are ideal anodes for high-energy rechargeable batteries. However, their poor coulombic efficiency and the associated safety issues due to dendritic metal deposition and large volume changes during metallic plating/stripping are the major causes that persistently hinder their practical energy-storage applications. Herein, Zn-containing carbon nanostructures derived from typical zeolitic imidazolate framework-8 (ZIF-8) are proposed as advanced metal anode materials for both Na and Li metal batteries. In this study; the three-dimensional interconnected porous surfaces confine metallic Na and Li within the nanostructures, filling the carbon scaffold, and covering the electrode surface to form stable solid electrolyte interphases. Based on the metal nucleation and growth results obtained through various electrochemical tests, Zn incorporation and pore morphology have been revealed to be the key factors that regulate the metal nucleation and metallic plating/stripping during cycling. Thus, the incorporation of Zn in the closed pores of a carbon nanostructure improves the cycle performance, even in carbonate electrolytes, and produces stable Na and Li metallic anodes for next-generation rechargeable batteries.

25 ENERGY STORAGE↗
DOE OSTI2023

Boosting the Low-Temperature Performance of Graphite Anodes by Creating an Electrochemically Active Interface

Graphite is the major anode material used in commercial lithium-ion batteries (LIBs). However, the sluggish ion-transfer kinetics associated with graphite anodes significantly restrict the operation of LIBs over a wide temperature. This is primarily due to their low reversible capacity and the substantial overpotential exhibited under low-temperature conditions. To address this limitation, we demonstrate herein an approach that involves grafting an electrochemically active lithium benzenesulfonate layer onto a graphite surface through a typical reduction reaction of diazonium cations, followed by ion exchange process. This surface modification reduces the charge transfer resistance of graphite anodes, leading to an excellent reversible capacity of ~150 mAh g –1 at low-temperatures (-20 °C, 0.1C). Electrochemical impedance spectroscopy indicates that both desolvation of the lithium ions outside the graphite, and lithium diffusion within the solid electrolyte interphase and graphite lattice are two crucial rate-limiting steps during the Li (de)lithiation, with the latter dominating during the low-temperature operation. In conclusion, these findings demonstrate a facile method for enhancing the low-temperature performance of graphite through surface modification and provide valuable insights into fundamental understandings that can guide the future design of better -low-temperature graphite anodes.

25 ENERGY STORAGE↗
DOE OSTI2020

Challenges in Lithium Metal Anodes for Solid-State Batteries

In this Perspective, we highlight recent progress and challenges related to the integration of lithium metal anodes in solid-state batteries. While prior reports have suggested that solid electrolytes may be impermeable to lithium metal, this hypothesis has been disproven under a variety of electrolyte compositions and cycling conditions. Herein, we describe the mechanistic origins and importance of lithium filament growth and interphase formation in inorganic and organic solid electrolytes. Multimodal techniques that combine real and reciprocal space imaging and modeling will be necessary to fully understand nonequilibrium dynamics at these buried interfaces. Currently, most studies on lithium electrode kinetics at solid electrolyte interfaces are completed in symmetric Li–Li configurations. To fully understand the challenges and opportunities afforded by Li-metal anodes, full-cell experiments are necessary. Lastly, the impacts of operating conditions on solid-state batteries are largely unknown with respect to pressure, geometry, and break-in protocols. Given the rapid growth of this community and the diverse portfolio of solid electrolytes, we highlight the need for detailed reporting of experimental conditions and standardization of protocols across the community.

25 ENERGY STORAGE↗
DOE OSTI2023

In situ microscopy and spectroscopy characterization of microsized Sn anode for sodium-ion batteries

Microsized Sn is a promising anode material for sodium-ion batteries in terms of cost, specific capacity, and volumetric energy density, which however suffers from huge volume changes and rapid cell degradation upon cycling. Despite recent advances via nanostructured electrode design and interface engineering, the correlation between mechanical stability, solid-electrolyte interphase (SEI) and reaction kinetics/reversibility remains controversial and elusive. Here, in this work, by combining in situ scanning electron microcopy and X-ray absorption spectroscopy as well as X-ray photoelectron spectroscopy, we have investigated the underlying electro-chemo-mechanical behavior and their coupling effects during charge/discharge of microsized Sn anode. Our results revealed that microsized Sn is pulverized into nanoparticles with simultaneous formation of numerous voids and pores upon the 1st charge/discharge, while the electrolytes composition plays a critical role on the consequent parasitic reactions and eventually the sodiation/de-sodiation reversibility. In contrast to carbonate-based electrolytes, ether-based electrolytes enabled formation of inorganic species dominated SEI with improved mechanical strength, thus leading to higher specific capacity and improved cycling stability. The present findings are crucial for future development of microsized anode materials for rechargeable batteries with high volumetric energy density.

25 ENERGY STORAGE↗
DOE OSTI2023

Probing the Formation of Cathode-Electrolyte Interphase on Lithium Iron Phosphate Cathodes via Operando Mechanical Measurements

Interfacial instabilities in electrodes control the performance and lifetime of Li-ion batteries. While the formation of solid-electrolyte interface (SEI) on anodes has received much attention, there is still lack of understanding about the formation of cathode-electrolyte interface (CEI) on the cathodes. To fill this gap, we report on dynamic deformations on lithium iron phosphate, LiFePO 4 cathodes during charge / discharge by utilizing in-operando digital image correlation, impedance spectroscopy and Cryo X-ray photoelectron spectroscopy. LiFePO4 cathodes were cycled in either LiPF 6 , LiClO 4 or LiTFSI- containing organic liquid electrolytes. Beyond the first cycle, Li-ion intercalation results in a nearly linear correlation between electrochemical strains and the state of (dis)-charge, regardless of the electrolyte chemistry. However, during the first charge in LiPF 6 - containing electrolyte, there is a distinct irreversible positive strain evolution at the onset of anodic current rise as well as current decay at around 4.0V. Impedance studies show the increase in surface resistance in the same potential window, suggesting the formation of CEI layers on the cathode. The chemistry of the CEI layer was characterized by X-ray photoelectron spectroscopy. LiF is detected in CEI layer starting as early as 3.4 V and Li $x$ PO $y$ F $z$ appeared at voltages higher than 4.0 V during the first charge. In conclusion, our approach offers new insights into the formation mechanism of CEI layers on the cathode electrodes, which is crucial for the development of robust cathode and electrolyte chemistries for higher performance batteries.

25 ENERGY STORAGE↗
DOE OSTI2022

Electrolytes Containing Triethyl Phosphate Solubilized Lithium Nitrate for Improved Silicon Anode Performance

An electrolyte consisting of lithium nitrate (LiNO3) and lithium difluoro(oxalato)borate (LiDFOB) in ethylene carbonate (EC), ethylmethyl carbonate (EMC), and triethyl phosphate (TEP) is used to improve the long-term cycling stability of silicon anodes. TEP was selected for its ability to dissolve LiNO 3 in carbonates to a concentration of ~0.2 M. The large amount of LiNO 3 combined with the LiDFOB salt leads to a capacity retention of 87.1% after one hundred cycles due to the formation of a relatively stable solid electrolyte interphase (SEI). Ex-situ surface analysis reveals that the SEI consists of oxalates, lithium alkyl carbonates, borates, and nitrate reduction products. By selecting two components which are preferentially reduced (LiNO 3 and LiDFOB), the SEI is able to inhibit continuous solvent decomposition and allows for improved electrochemical cycling for pure silicon anodes.

25 ENERGY STORAGE↗
DOE OSTI2023

Li 3– x Zr x (Ho/Lu) 1– x Cl 6 Solid Electrolytes Enable Ultrahigh-Loading Solid-State Batteries with a Prelithiated Si Anode

We report two new families of lithium metal chloride solid electrolytes Li 3–x Zr x (M) 1–x Cl 6 (0 ≤ x ≤ 0.8; M = Ho or Lu) with ionic conductivities of up to 1.8 mS cm –1 and a low activation energy of 0.34 eV. Structural elucidation via high-resolution neutron diffraction determines the Li ion distribution in trigonal Li 3 HoCl 6 , orthorhombic-I Li 3 LuCl 6 , and orthorhombic-II Li 2.4 Zr 0.6 (Ho/Lu) 0.4 Cl 6 . The last compound exhibits well-connected Li-ion pathways and abundant Li-ion carriers/vacancies to promote diffusion. All-solid-state batteries with Li 2.6 Zr 0.4 (Ho/Lu) 0.6 Cl 6 solid electrolytes and NCM85 cathodes exhibit stable cycling up to 4.6 V vs Li + /Li, which is even preserved up to 4.8 V. Stable cathode interphases are formed for both electrolytes upon cycling to 4.3, 4.6, and 4.8 V cutoff potentials, as identified by a ToF-SIMS analysis. Solid-state cells with a prelithiated Li 0.7 Si anode exhibit a significantly increased initial coulombic efficiency of 94.5% compared to Si and a high areal capacity of up to 16.3 mAh·cm –2 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗