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Tang, Wei

Publications and source records attributed to Tang, Wei.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Microsphere LiMn 0.6 Fe 0.4 PO 4 /C cathode with unique rod-like secondary architecture for high energy lithium ion batteries

LiMn x Fe 1-x PO 4 /C is considered a promising next-generation cathode material with significant commercial potential, inheriting the safety of LiFePO 4 while offering higher energy densities. However, the extremely low conductivity and the Jahn-Teller effect induced by Mn 3+ limit its practical capacity and rate performance. Effective modifications can be achieved through particle nanonization and uniform carbon coating. Here, in this work, we synthesized microspherical LiMn 0.6 Fe 0.4 PO 4 /C cathode materials using a hydrothermal method combined with spray drying carbon coating. The cathode material exhibits a microsphere structure composed of aggregated nanorods with a uniform 3 nm carbon coating, showing good dispersibility, small specific surface area and high tap density. In-situ diffraction analysis showed that expanding the single-phase solid solution region during (de)lithiation can reduce the energy barrier for electron transport, improve the kinetics of the (dis)charge process, and enhance both cycling and rate performance. The initial capacity at 0.1C can reach 155 mAh/g, and the capacity remains at 133.5 mAh/g with a retention rate of 97.1 % after 300 cycles. The synergistic effect of particle nanonization and uniform carbon coating endows the LiMn x Fe 1-x PO 4 /C material with excellent electrochemical performance.

25 ENERGY STORAGE↗
DOE OSTI2024

Ameliorating the sodium storage performance of hard carbon anode through rational modulation of binder

Hard carbon anodes have emerged as promising candidates for sodium-ion batteries due to their inherent advantages. Nevertheless, the surface imperfections in these materials often culminate in irreversible electrolyte consumption, fostering the development of a heterogeneous and fragile solid electrolyte interface (SEI), thereby compromising the initial Coulombic efficiency (ICE). Here, drawing inspiration from the catalytic potential of C=O (carbonyl) bonds in directing preferential salt reduction, we introduce a novel strategy that leverages the modulation of the binder, a long-term overlooked pivotal components in the electrode process. Specifically, Polymethyl methacrylate (PMMA), abundant in C=O groups, is partially substituted for PVDF, ensuring robust adhesion of the electrode material to the current collector while preserving superior mechanical properties. The accurate combination of two binders with delightful compatibility in the state-of-art electrode process, can promote a uniform formation of the SEI on the hard carbon surface enriched in inorganic components, which can ensure long-term interfacial stability and suppresses excessive solvent decomposition and facilitates Na + transfer at the interface. Consequently, the initial Coulombic efficiency of the hard carbon anode with 70 %PMMA binder achieves 86 %, with prominent cycling stability (88 % capacity retention over 500 cycles) at a high current density of 1.2 A g −1 . When paired with high loading cathodes to assemble the pouch cell, it also demonstrates stable operational scenarios.

25 ENERGY STORAGE↗
DOE OSTI2024

ARQUIN: Architectures for Multinode Superconducting Quantum Computers

Many proposals to scale quantum technology rely on modular or distributed designs wherein individual quantum processors, called nodes, are linked together to form one large multinode quantum computer (MNQC). One scalable method to construct an MNQC is using superconducting quantum systems with optical interconnects. However, internode gates in these systems may be two to three orders of magnitude noisier and slower than local operations. Surmounting the limitations of internode gates will require improvements in entanglement generation, use of entanglement distillation, and optimized software and compilers. Still, it remains unclear what performance is possible with current hardware and what performance algorithms require. In this article, we employ a systems analysis approach to quantify overall MNQC performance in terms of hardware models of internode links, entanglement distillation, and local architecture. We show how to navigate tradeoffs in entanglement generation and distillation in the context of algorithm performance, lay out how compilers and software should balance between local and internode gates, and discuss when noisy quantum internode links have an advantage over purely classical links. Here, we find that a factor of 10–100× better link performance is required and introduce a research roadmap for the co-design of hardware and software towards the realization of early MNQCs. While we focus on superconducting devices with optical interconnects, our approach is general across MNQC implementations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

The Role and Substitution of Cobalt in the Cobalt‐Lean/Free Nickel‐Based Layered Transition Metal Oxides for Lithium Ion Batteries

Here, the Nickel-based layered transition metal oxide cathode represented by NCM (LiNi x Co y Mn z O 2 , x+y+z=1) and NCA (LiNi x Co y Al z O 2 , x+y+z=1) is widely used in the electric vehicle market due to its specific capacity and high working potential, in which Cobalt (Co) plays a huge role in improving the structural stability during the cycle. However, the limited supply of Co, due to its scarcity and the influence of geopolitics, poses a significant constraint on the further advancement of the Nickel-based layered transition metal oxide cathode in the field of energy storage. In this paper, the mechanism of Co in the Nickel-based layered transition metal oxides is reviewed, including its critical role for structural stability such as the inhibition of cationic mixing and the release of lattice oxygen et al. Subsequently, it outlines various strategies to enhance the performance of Co-lean/free materials, such as ion doping, including single-ion doping and multi-ion co-doping, and various surface coating strategies, so as to eliminate the adverse effects of Co loss on materials. Ultimately, this paper offers a glimpse into the promising future of Cobalt-free strategies for high performance of Nickel-based layered transition metal oxides.

25 ENERGY STORAGE↗
DOE OSTI2024

Deciphering Chemical/Electrochemical Compatibility of Li 3 InCl 6 in 5.2 V High-Voltage LiCoO 2 All-Solid-State Batteries

Large interfacial resistance is a widely recognized impediment to the advancement of high-voltage, all-solid-state batteries. However, a comprehensive understanding of the fundamental cause behind the interfacial resistance between solid electrolytes and typical layered oxide cathodes has not yet been achieved. Here, we investigated the high-voltage stability of Li 3 InCl 6 and elucidated the underlying interfacial electrochemical reactions between LiCoO 2 and Li 3 InCl 6 . Further, the pairing of Li 3 InCl 6 with LiCoO 2 exhibited a superior capacity retention of 73.6% even at 5.2 V, much higher than 28.2% charged at 4.6 V in lithium-ion batteries after 70 cycles. The enhanced high-voltage stability of ASSBs is attributed to the stable interface formed between LiCoO 2 and Li 3 InCl 6 and the reinforced surface and bulk structure stability. On the other hand, the ultrahigh voltage still causes the partial decomposition of Li 3 InCl 6 and generates interfacial compounds such as InClO and cobalt and indium chlorides/oxides.

25 ENERGY STORAGE↗
DOE OSTI2024

Research Progress and Perspectives on Pre‐Sodiation Strategies for Sodium‐Ion Batteries

Sodium‐ion batteries (SIBs) with abundant elements have garnered significant attention from researches as a promise compensation to lithium‐ion batteries (LIBs). However, the large‐scale commercial application of SIBs is partially hindered by the limited initial coulombic efficiency (ICE) due to the irreversible formation of solid electrolyte interphase (SEI) and intercalation into the defects in the anode. Similar to pre‐lithiation techniques, pre‐sodiation approaches are considered to be one of the most direct and effective way to compensate for the loss of active sodium at the anode side of SIBs during the initial cycle. In this context, additional sodium ions are pre‐injected to the cathode/anode material by chemical/electrochemical methods, aiming to improve battery span life and energy density. Here, this review delves into the necessity and impact of pre‐sodiation techniques, compiling the latest research progress, for instance, self‐sacrificing cathode additives, over‐sodiated cathode materials, direct contact and solution chemical pre‐sodiation. Notably, the research mechanisms underlying solution chemical pre‐sodiation are highlighted. This comprehensive overview aims to foster a deeper understanding of the pre‐sodiation techniques and expects to provide guidance for realizing the commercial application of high energy density sodium‐ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2024

A comprehensive review on liquid electrolyte design for low-temperature lithium/sodium metal batteries

Lithium/sodium metal batteries (LMBs/SMBs) possess immense potential for various applications due to their high energy density. Nevertheless, LMBs/SMBs are highly susceptible to the detrimental effects of an unstable solid electrolyte interphase (SEI) and dendrites during practical applications, particularly pronounced in low-temperature environments. Furthermore, sluggish ion transportation further compromises the cycling stability of LMBs/SMBs at low temperatures. To achieve stable operation of LMBs/SMBs at low temperatures, researchers have made numerous efforts including electrolyte optimization aimed at creating stable SEIs and suppressing the metal dendrites under low temperature conditions. Despite the significant advancements made recently in the liquid electrolyte design, there remains considerable hurdle in electrolyte engineering for practical low-temperature, high energy density LMBs/SMBs, calling for a profound comprehension of the intricate interplay between the electrochemical reaction kinetics and electrolyte compositions. Here, this review provides a thorough overview of various strategies in optimizing liquid electrolytes covering weakly solvating electrolytes, concentration-designed electrolytes, and solvation structure-designed electrolytes, to address the challenges faced by LMBs/SMBs at low temperatures, including slow reaction kinetics and the difficulties in Li + /Na + solvation/desolvation. Furthermore, this review discusses future prospects for the advancement of this field, intending to provide valuable insights and support for subsequent research undertakings.

25 ENERGY STORAGE↗
DOE OSTI2024

Hot-Roll Fabrication of Anisotropic Nanograin Nd-Fe-B Magnet

Nd-Fe-B based magnets have the highest energy product among all permanent magnets, which is required for numerous clean energy technologies. For higher temperature applications (T > 150°C), additions of heavy rare earth elements (HREEs) such as Dy are required to maintain sufficient coercivity during operation. Additions of Dy are expensive. Thus, it is desirable to reduce the need for HREEs by reducing the grain size to the nanoscale, which increases the coercivity and decreases its temperature dependence. Here, we report a novel nanograin Nd-Fe-B magnet fabrication method that is continuous and inexpensive. The process uses mechanically milled Nd-Fe-B melt-spun flakes as feedstock powder that is packed into a metal vessel and then hot rolled to form a fully dense and highly textured strip magnet with tailored thicknesses, down to 800 µm. Finally, using this process, fully dense nanograin bulk magnets can be synthesized in minutes compared to the traditional multi-step processes that are typically low throughput.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Effect of different grain boundary diffusion alloys on magnetic properties of Dy-free sintered NdFeB magnet

Dy-free sintered magnets were fabricated by blending Neo powder with different grain boundary diffusion alloy powders. Cu, CeAl and CeAlCu have a negative effect on H cj of magnets, while PrAlCu and AlCuGa have a positive effect. The PrAlCu-added magnet achieves the best magnetic properties among all magnets with the additions of different diffusion alloys. With increasing PrAlCu from 0-10 wt.%, H cj of the magnets gradually increases from the original 14.5 kOe to 19.2 kOe. The magnet with 7.5 wt.% PrAlCu obtains a H cj of 18 kOe and (BH) max of 39.1 MGOe. It is found that Pr and Cu in PrAlCu alloy is mainly distributed at grain boundary and triple junctions, leading to a reduced coupling among grains, thus an enhanced H cj . Here, the grain boundary engineering by adding an appropriate alloy is an effective method to improve H cj of Dy-free NdFeB magnets.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Effects of Post-sintering Annealing on (NdLa)-(FeCo)-B Magnets

A common limitation of La substitutions into (Nd, La) 2 Fe 14 B magnets is the reduction of the anisotropy field (H a ), which decreases magnet coercivity (H cj ). In this study, adding a small amount of Pr-Cu to a La-containing neo magnet may modify the grain boundary (GB), which can help recover a fraction of the degraded H cj . An optimal GB modification requires a carefully designed post-sinter heat treatment, which is the focus of this work on characterizing the effects of multi-step post-sintering annealing on the evolutions of microstructure and magnetic properties. We find that Nd and Cu concentrations at GBs and triple junctions (TJs) increase when the annealing temperatures are lowered. Annealing temperatures of 580°C and 480°C (near rare-earth-rich eutectic temperatures) enabled the development of a thick and continuous GB phase, which helps to magnetically decouple the grains, and, thus, enhance H cj . For the alloy with 25% Nd replaced by La, and with the addition of 7.5 wt.% of Pr 68 Cu 32 as GB modifier, the optimized multi-step post-sinter annealing improved the H cj from 4.8 kOe to 9 kOe.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Advanced neutron absorber Ni-Cr-Mo-Gd alloys seawater corrosion mechanism and susceptibility study

Previous studies demonstrated the corrosion susceptibility of advanced neutron absorber (ANA) Ni-Cr-Mo-Gd in a seawater environment but remained inconclusive. In this paper, scanning electron microscopy was employed to identify the corrosion phase in Ni-Cr-Mo-Gd, and computational thermodynamic simulation was used to study phase corrosion potentials. Results showed that the Ni 5 Gd second phase, distributed along FCC grain boundaries in Ni-Cr-Mo-Gd, has lower corrosion potential than the substrate. Furthermore, heat treatment and alloy chemistry adjustment would not ameliorate the ANA corrosion susceptibility. Finally, isolating the Ni 5 Gd from the corrosion medium through advanced manufacturing is a viable way to improve the ANA corrosion resistance.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Study of Mechanical Properties, Microstructure, and Residual Stresses of AISI 304/304L Stainless Steel Submerged Arc Weld for Spent Fuel Dry Storage Systems

The confinement boundaries of spent nuclear fuel (SNF) canisters are typically fusion welded. Welded microstructures, strain hardening, and residual stresses combined with a chemically aggressive, chloride-rich environment led to concerns that the welded canister may be susceptible to chloride-induced stress corrosion cracking (CISCC). A comprehensive understanding of the modification of stainless steel (SS) metallurgical and mechanical properties by fusion welding could accelerate the predictive analysis of CISCC susceptibility. This paper describes a submerged arc welding (SAW) procedure that was developed and qualified on 12.7 mm (0.5 in.) thick AISI 304/304L SS to produce joints in a way similar to actual SNF canister manufacturing. This procedure has the potential to reduce the production cost and weld CISCC susceptibility by using fewer welding passes and lower heat input than current industrial applications. Global and local mechanical behaviors and properties, as well as residual stress distributions on the welded joint, were studied. The results indicate that hardness values in the fusion zone (FZ) and heat-affected zone (HAZ) are slightly higher than that of the base metal. Strain localization was presented in the HAZ before the tensile stress reached its maximum value, and then it shifted to the FZ. The specimen finally broke in the FZ. High tensile residual stresses exhibited in the FZ and the nearby HAZ suggest the highest CISCC-susceptible spots. The maximum tensile residual stresses were along the welding direction, indicating that if cracks occur, they would be perpendicular to the welding direction. This study involved developing and qualifying a SAW procedure for SNF canister production. The new procedure yielded cost savings (SAW working efficiency increased by about 80%), improved mechanical properties, and presented moderate residual stresses. Analysis revealed that the welded joint’s low-stress and high-stress damage assessments may be affected by shifts in the strain localization spot under loading.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Solid Electrolyte Bimodal Grain Structures for Improved Cycling Performance

Here, the application of solid-state electrolytes in Li batteries is hampered by the occurrence of Li-dendrite-caused short circuits. To avoid cell failure, the electrolytes can only be stressed with rather low current densities, severely restricting their performance. As grain size and pore distributions significantly affect dendrite growth in ceramic electrolytes such as Li 7 La 3 Zr 2 O 12 and its variants; here, a “detour and buffer” strategy to bring the superiority of both coarse and fine grains into play, is proposed. To validate the mechanism, a coarse/fine bimodal grain microstructure is obtained by seeding unpulverized large particles in the green body. The rearrangement of coarse grains and fine pores is fine-tuned by changing the ratio of pulverized and unpulverized powders. The optimized bimodal microstructure, obtained when the two powders are equally mixed, allows, without extra interface decoration, cycling for over 2000 h as the current density is increased from 1.0 mA·cm -2 , and gradually, up to 2.0 mA·cm -2 . The “detour and buffer” effects are confirmed from postmortem analysis. The complex grain boundaries formed by fine grains discourage the direct infiltration of Li. Simultaneously, the coarse grains further increase the tortuosity of the Li path. This study sheds light on the microstructure optimization for the polycrystalline solid-state electrolytes.

25 ENERGY STORAGE↗
DOE OSTI2024

Development of Surface Treatment Solutions for Stamping Tools Fabricated via Additive Manufacturing

Oak Ridge National Laboratory (ORNL) and H.E.F. USA, Inc. (HEF) partnered to develop wear resistant surface treatment of additive manufactured steels for stamping die applications under CRADA agreement NFE-19-07909. This project aimed at evaluating the ARCOR® process, developed by HEF, to improve the surface behavior of 410SS (stainless steel), 410NiMo SS, 630 SS, and Maraging 250 steel coupons and demo components, fabricated via wire arc additive manufacturing (WAAM), with and without post print heat treatment. The peak hardness achieved was ~1000 HV and above (Up to 1300 HV) for all materials under proper processing parameters, and far exceeded the target hardness of 746 HV (60 HRC). Finally, stamping tools were printed and nitrocarburized with the optimum parameters, and then went through 500 fabrication cycles. Characterization of the used 17-4PH stamping tool discovered no crack or delamination in the nitrocarburized layer and the interface between the nitrocarburized layer and substrate.

36 MATERIALS SCIENCE↗
DOE OSTI2023

HetArch: Heterogeneous Microarchitectures for Superconducting Quantum Systems

Noisy Intermediate-Scale Quantum Computing (NISQ) has dominated headlines in recent years, with the longer-term vision of Fault-Tolerant Quantum Computation (FTQC) offering significant potential but at currently intractable resource costs and quantum error correction (QEC) overheads. For problems of interest, FTQC will require millions of physical qubits with long coherence times, high-fidelity gates, and compact sizes to surpass classical systems. Just as heterogeneous specialization has offered scaling benefits in classical computing, it is likewise gaining interest in FTQC. However, systematic use of heterogeneity in either hardware or software elements of FTQC systems remains a serious challenge due to the vast design space and the variable physical constraints. This paper meets the challenge of making heterogeneous FTQC design practical by introducing HetArch, a toolbox for designing heterogeneous quantum systems, and using it to explore heterogeneous design scenarios. Using a hierarchical approach, we successively break quantum algorithms into smaller operations (akin to classical application kernels), thus greatly simplifying the design space and resulting tradeoffs. Specializing to superconducting systems, we then design optimized heterogeneous hardware composed of varied superconducting devices, abstracting physical constraints into design rules that enable devices to be assembled into standard cells optimized for specific operations, which, in turn, form heterogeneous modules optimized for quantum subroutines. Finally, we provide a heterogeneous design space exploration framework which reduces the simulation burden by a factor of 10^4 or more and allows us to characterize optimal design points. We use these techniques to design superconducting quantum modules for entanglement distillation, error correction, and code teleportation, reducing error rates by 2.6×, 10.7×, and 3.4× compared to homogeneous systems.

Quantum Computing, Quantum Physics, Computer Archi↗
DOE OSTI2023

Defect Recognition for Eddy Current Testing of Spent Nuclear Fuel Canister using Convolutional Neural Network

This paper proposes an accurate and robust defect detection solution for 304L and 306L stainless steel (SS) weld. In the proposed solution, Eddy current testing (ECT) is employed to generate 2-dimensional (2D) data for samples under test with defects. The 2D data can be treated as images for deep learning-based defect detection. Since convolutional neural networks (CNNs) are powerful in processing images, CNN is employed in this study for defect detection. Experiments are conducted on a submerged arc welding (SAW) 304L SS weld sample with an artificial crack generated by waterjet cutting. The ECT data on this seeded fault sample is utilized to verify the proposed solution. For this purpose, the ECT measurement are separated as from Fault area and Normal area, which are used for CNN training. After training, the testing data is used for verification. Experimental results demonstrate the feasibility and effectiveness of the proposed solution.

Niu, Guangxing↗