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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Chemical Heterointerface Engineering on Hybrid Electrode Materials for Electrochemical Energy Storage

Abstract The chemical heterointerfaces in hybrid electrode materials play an important role in overcoming the intrinsic drawbacks of individual materials and thus expedite the in‐depth development of electrochemical energy storage. Benefiting from the three enhancement effects of accelerating charge transport, increasing the number of storage sites, and reinforcing structural stability, the chemical heterointerfaces have attracted extensive interest and the electrochemical performances of hybrid electrode materials have been significantly optimized. In this review, recent advances regarding chemical heterointerface engineering in hybrid electrode materials are systematically summarized. Especially, the intrinsic behaviors of chemical heterointerfaces on hybrid electrode materials are refined based on built‐in electric field, van der Waals interaction, lattice mismatch and connection, electron cloud bias and chemical bond, and their combination. The strategies for introducing chemical heterointerfaces are classified into in situ local transformation, in situ growth, cosynthesis, and other strategy. The recent progress about the chemical heterointerfaces engineering specially focusing on metal‐ion batteries, supercapacitors, and Li–S batteries are introduced in detail. Furthermore, the classification and characterization of chemical heterointerfaces are briefly described. Finally, the emerging challenges and perspectives about future directions of chemical heterointerface engineering are proposed.

Li, Wenbin↗
DOE OSTI2022

Dual Passivation of Cathode and Anode through Electrode–Electrolyte Interface Engineering Enables Long-Lifespan Li Metal–SPAN Batteries

The reliability and durability of lithium metal (Li 0 )–sulfur batteries are largely limited by the undesired Li 0 plating-stripping irreversibility and the detrimental polysulfide dissolution, yet approaches that can simultaneously address the above anodic and cathodic problems are scarce. In this study, we report the stable operation of a Li 0 -SPAN (sulfurized polyacrylonitrile) battery via an anode–cathode dual-passivation approach. By combination of a fluorinated localized high concentration electrolyte (LHCE) and a Li 3 N-forming additive (TMS-N 3 ), robust and highly conductive electrode passivation layers are formed in situ on the surface of both the Li 0 anode and the SPAN cathode. The resulting highly reversible, dendrite-free, and high-density Li 0 plating morphology enables a high Coulombic efficiency of 99.4%. Advanced tender energy X-ray spectroscopy also reveals the eliminated Li 2 S formation and minimized polysulfide dissolution in SPAN cathodes, leading to a high capacity of 580 mAh/g SPAN and stable cycling with negligible capacity decay (0.7%) for 800 cycles. This electrode–electrolyte interphase engineering strategy has tackled the major limitations of Li–S batteries in both ether- and carbonate-based electrolyte systems and under a wide temperature range from –10 to +50 °C, thus providing insightful guidelines for the rational design of highly durable and high-energy-density Li 0 -S batteries.

25 ENERGY STORAGE↗
DOE OSTI2018

Substrate Engineered Interconnected Graphene Electrodes with Ultrahigh Energy and Power Densities for Energy Storage Applications

Supercapacitors combine the advantages of electrochemical storage technologies like high energy density batteries and high power density capacitors. At 5-10 W h Kg -1 , the energy densities of current supercapacitors are still significantly lower than energy densities of lead acid (20-35 W h Kg -1 ), Ni-metal hydride (40-100 W h Kg -1 ) and Li-ion (120-170 W h Kg -1 ) batteries. Recently, graphene based supercapacitors have shown energy density of 40-80 W h kg -1 . However, their performance is mainly limited due to the reversible agglomeration and restacking of individual graphene layers caused by π-π interactions. The restacking of graphene layers leads to significant decrease of ion-accessible surface area and the low capacitance of graphene based supercapacitors. Here, we introduce a microstructure substrate based method to produce fully delaminated and stable interconnected graphene structure using flash reduction of GO in a few seconds. With this structure, here we achieve the highest amount of volumetric capacitance obtained so far by any type of pure carbon based material. The affordable and scalable production method is capable of producing electrodes with energy density of 0.37 Wh cm -3 and power density of 416.6 W cm -3 . This electrode maintained more than 91 % of its initial capacitance after 5000 cycles. Moreover, combining with ionic liquid, this solvent free graphene electrode material is highly promising for on-chip electronics, micro supercapacitors as well as high power applications.

25 ENERGY STORAGE↗
DOE OSTI2021

Computational design of microarchitected porous electrodes for redox flow batteries

Porous electrodes are used as the core reactive component across electrochemical technologies. In flowing systems, controlling the fluid distribution, species transport, and reactive environment is critical to attaining high performance. However, conventional electrode materials like felts and papers provide few opportunities for precise engineering of the electrode and its microstructure. To address these limitations, architected electrodes composed of unit cells with spatially varying geometry determined via computational optimization are proposed. Resolved simulation is employed to develop a homogenized description of the constituent unit cells. These effective properties serve as inputs to a continuum model for the electrode when used in the negative half-cell of a vanadium redox flow battery. Porosity distributions minimizing power loss are then determined via computational design optimization to generate architected porosity electrodes. The architected electrodes are compared to bulk, uniform porosity electrodes and found to lead to increased power efficiency across operating flow rates and currents. The design methodology is further used to generate a scaled-up electrode with comparable power efficiency to the bench-scale systems. Finally, the variable porosity architecture and computational design methodology presented here thus offers a novel pathway for automatically generating spatially engineered electrode structures with improved power performance.

25 ENERGY STORAGE↗
DOE OSTI2019

Surface Engineering of 3D Gas Diffusion Electrodes for High‐Performance H 2 Production with Nonprecious Metal Catalysts

Abstract In this work, a methodology is demonstrated to engineer gas diffusion electrodes for nonprecious metal catalysts. Highly active transition metal phosphides are prepared on carbon‐based gas diffusion electrodes with low catalyst loadings by modifying the O/C ratio at the surface of the electrode. These nonprecious metal catalysts yield extraordinary performance as measured by low overpotentials (51 mV at −10 mA cm −2 ), unprecedented mass activities (>800 A g −1 at 100 mV overpotential), high turnover frequencies (6.96 H 2 s −1 at 100 mV overpotential), and high durability for a precious metal‐free catalyst in acidic media. It is found that a high O/C ratio induces a more hydrophilic surface directly impacting the morphology of the CoP catalyst. The improved hydrophilicity, stemming from introduced oxyl groups on the carbon electrode, creates an electrode surface that yields a well‐distributed growth of cobalt electrodeposits and thus a well‐dispersed catalyst layer with high surface area upon phosphidation. This report demonstrates the high‐performance achievable by CoP at low loadings which facilitates further cost reduction, an important part of enabling the large‐scale commercialization of non‐platinum group metal catalysts. The fabrication strategies described herein offer a pathway to lower catalyst loading while achieving high efficiency and promising stability on a 3D electrode.

Sanchez, Joel↗
DOE OSTI2018

Ambient Electrosynthesis of Ammonia: Electrode Porosity and Composition Engineering

Ammonia, a key precursor for fertilizer production, convenient hydrogen carrier, and emerging clean fuel, plays a pivotal role in sustaining life on Earth. Currently, the main route for NH 3 synthesis is by the heterogeneous catalytic Haber–Bosch process (N 2 +3 H 2 →2 NH 3 ), which proceeds under extreme conditions of temperature and pressure with a very large carbon footprint. Herein we report that a pristine nitrogen–doped nanoporous graphitic carbon membrane (NCM) can electrochemically convert N 2 into NH 3 in an acidic aqueous solution under ambient conditions. The Faradaic efficiency and rate of production of NH 3 on the NCM electrode reach 5.2 % and 0.08 g m –2 h –1 , respectively. Functionalization of the NCM with Au nanoparticles dramatically enhances these performance metrics to 22 % and 0.36 gm –2 h –1 , respectively. In conclusion, as this system offers the potential to be scaled to industrial levels it is highly likely that it might displace the century-old Haber–Bosch process.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
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 OSTI2019

Enhancing the Rate Capability of Niobium Oxide Electrode through Rare‐Earth Doping Engineering

Abstract Niobium oxide is considered one of the most promising electrode materials for ultrafast electrochemical energy storage devices with high energy density. In this work, we first found that trace amounts (<1 %) of Yb 3+ doping remarkably enhanced the rate capability of T−Nb 2 O 5 , which was further proved to be because of the formation of a thin layer of amorphous YbNbO x . The capacity of YbNbO x ‐coated Nb 2 O 5 reached 124 mAh g −1 at 20 C, which is the highest value reported among pristine Nb 2 O 5 electrodes. Besides, we found that doping with other rare‐earth elements such as Nd 3+ , Sm 3+ , and Gd 3+ can also improve the rate capability of T−Nb 2 O 5 . It can be concluded that rare‐earth doping can be an effective and robust method to enhance the intrinsic rate performance of electrode materials without complicated modifications.

Yin, Dandan↗
DOE OSTI2023

Engineering Redox Flow Battery Electrodes with Spatially Varying Porosity Using Non‐Solvent‐Induced Phase Separation

Redox flow batteries (RFBs) are a promising electrochemical platform for efficiently and reliably delivering electricity to the grid. Within the RFB, porous carbonaceous electrodes facilitate electrochemical reactions and distribute the flowing electrolyte. Tailoring electrode microstructure and surface area can improve RFB performance, lowering costs. Electrodes with spatially varying porosity may increase electrode utilization and provide surface area in reaction‐limited zones; however, the efficacy of such designs remains an open area of research. Herein, a non‐solvent‐induced phase‐separation (NIPS) technique that enables the reproducible synthesis of macrovoid‐free electrodes with well‐defined across‐thickness porosity gradients is described. The monotonically varying porosity profile is quantified and the physical properties and surface chemistries of porosity‐gradient electrodes are compared with macrovoid‐containing electrode, also synthesized by NIPS. Then, the electrochemical and fluid dynamic performance of the porosity‐gradient electrodes is evaluated, exploring the effect of changing the direction of the porosity gradient and benchmarking against the macrovoid‐containing electrode. Lastly, the performance is examined in a vanadium RFB, finding that the porosity‐gradient electrode outperforms the macrovoid electrode, is independent of gradient direction, and performs favorably compared to advanced electrodes in the contemporary literature. It is anticipated that the approach motivates further exploration of microstructurally tailored electrodes in electrochemical systems.

25 ENERGY STORAGE↗
DOE OSTI2024

Exploring the potential and impact of single-crystal active materials on dry-processed electrodes for high-performance lithium-ion batteries

Roll-to-roll powder-to-film dry processing (DP) and single-crystal (SC) active materials (AMs) with many advantages are two hot topics of lithium-ion batteries (LIBs). However, DP of SC AMs for LIBs is rarely reported. Consequently, the impact of SC AMs on dry-processed LIBs is not well understood. Herein, for the first time, via a set of experimental and theoretical studies of the conventional polycrystalline-AM- and SC-AM-based DPed electrodes (DPEs), this work not only reports a high-performance dry SC-AM cathode for LIB manufacturing, but also establishes some fundamental understanding of SC-based dry-processed electrodes, including their morphology, structure, mechanical strength, electronic conductivity and LIB electrochemical behavior. Further, the results suggest that DP of SC AMs is promising, which can dramatically improve the electrochemical kinetics at electrode level and particle level. Specifically, for the rate capability and long-term cyclability in full cells, SC DPEs exhibit a discharge specific capacity of 152.1 mAh g -1 at 1C and a capacity retention rate of 79.9 % at C/3 over 500 cycles, which are superior to those of PC DPEs (135.6 mAh g -1 and 68.3 %) at the same conditions and are further confirmed by the simulation data from the theoretical modelling study. Therefore, this comprehensive work marks a significant milestone for DP strategy and SC AMs, enlightening future research and development of LIB manufacturing.

25 ENERGY STORAGE↗
DOE OSTI2023

Unraveling the impact of the degree of dry mixing on dry-processed lithium-ion battery electrodes

Dry processing of lithium-ion battery electrodes facilely realizes the powder-to-film manner, which is thus regarded as a highly promising strategy for lithium-ion battery manufacturing. However, a fundamental understanding of the impact of the involved dry mixing is still rarely reported. In this work, the degree of dry mixing is monitored by the dry mixing time, and a set of dry-processed electrodes with different degree of dry mixing is accordingly prepared and comprehensively studied. This work novelly reveals that the degree of dry mixing exhibits pronounced impact on the morphology, the homogeneity of electrode components and the degree of PTFE fiberization, which leads to difference in the mechanical strength and electrochemical performance of dry-processed electrodes. Accordingly, it is suggested that a moderate degree of dry mixing is preferred for high-performance dry-processed lithium-ion battery electrodes.

25 ENERGY STORAGE↗