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Zou, Min

Publications and source records attributed to Zou, Min.

11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Fabrication method for a component having magnetic and non-magnetic dual phases

Methods for forming a dual-phase magnetic component from an initial component comprising a non-magnetic austenite composition are provided. The method may include: forming a coating on a portion of the surface of the initial component to form a masked area while leaving an unmasked area thereon. Thereafter the initial component may be heated to a treatment temperature such that nitrogen diffuses out of the unmasked area of the initial component to transform the non-magnetic austenite composition to a magnetic phase in the unmasked area. Thereafter, the initial component may be cooled from the treatment temperature to form a dual-phase magnetic component having a magnetic region corresponding to the unmasked area and a non-magnetic region corresponding to the masked area.

Huang, Shenyan↗
DOE OSTI2023

Simultaneously improved J sc and V oc achieving 19.15% efficiency in ternary blend polymer solar cell containing a Y-type acceptor with thiophene based end groups

Simultaneously enhancing the short-circuit current density (J sc ) and open-circuit voltage (V oc ) of current state-of-the-art polymer solar cells (PSCs) containing wide bandgap polymers as donors and Y6 derivatives as acceptors is of great challenge but essential for further improvement of the photovoltaic performances. Here, in this work, two Y-type non-fullerene acceptors of BTP-T and BTP-TCl were designed and successfully synthesized with relatively weak electron-accepting thiophene based end groups, where blue-shifted absorption and upshifted LUMO energy levels were achieved to fill the well-known absorption gap at 700 nm of typical binary devices based Y-type molecules and rise the output voltage, respectively. Simultaneously increased J sc and V oc were achieved in ternary blend devices containing D18:BTP-eC9:BTP-TCl with a significantly improved PCE up to 19.15 %, which is over 7 % increase compared to the binary device. Our results illustrated the great potential of rational design of Y6 derivatives for constructing ternary PSCs to improve their performances.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Atomic layer deposition of lithium zirconium oxides for the improved performance of lithium-ion batteries

Recently there has been increasing interest to develop lithium-containing films as solid-state electrolytes or surface coatings for lithium-ion batteries (LIBs) and related systems. Here, in this study, we for the first time investigated the thin film growth of lithium zirconium oxides (Li x Zr y O or LZOs) through combining two individual atomic layer deposition (ALD) processes of ZrO 2 and LiOH, i.e., sub-ALD of ZrO 2 and LiOH. We revealed that the hygroscopic nature of the LiOH component has a big impact on the growth of LZOs. We found that an increased temperature to 225 °C was more effective than an elongated purge to mitigate the adverse effects of physisorbed H 2 O. We further discovered that, during the resultant LZO super-ALD processes, the growth of sub-ALD LiOH has been promoted while the growth of sub-ALD ZrO 2 has been inhibited. In this study, a suite of instruments has been applied to characterize the LZO super-ALD processes and the resultant LZO films, including in situ quartz crystal microbalance (QCM), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), atomic force microscopy (AFM), synchrotron-based X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Furthermore, we applied the resulting LZO films over LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622) cathodes in LIBs and demonstrated that the LZO coating films could evidently improve the lithium-ion insertion and extraction rates of the NMC622 electrodes up to 3.4 and 2.6 times, respectively. The LZO-coated NMC622 cathodes exhibited much better performance than the uncoated NMC622 ones.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Molecular Layer Deposition of Crosslinked Polymeric Lithicone for Superior Lithium Metal Anodes

In this work, we for the first time developed a novel lithium-containing crosslinked polymeric material, a lithicone that enables excellent protection effects over lithium (Li) metal anodes. This new lithicone was synthesized via an accurately controllable molecular layer deposition (MLD) process, in which lithium tert -butoxide (LTB) and glycerol (GL) were used as precursors. The resultant LiGL lithicone was analyzed using a suite of characterizations. Furthermore, we found that the LiGL thichicone could serve as an exceptional polymeric protection film over Li metal anodes. Our experimental data revealed that the Li electrodes coated by this LiGL lithicone can achieve a superior cycling stability, accounting for an extremely long cyclability of >13,600 Li-stripping/plating cycles and having no failures so far in Li/Li symmetric cells at a current density of 5 mA/cm 2 and an areal capacity of 1 mAh/cm 2 . We found that, with a sufficient protection by this LiGL coating, Li electrodes could realize long-term stable cyclability with little formation of Li dendrites and solid electrolyte interphase. This novel LiGL represents a facile and effective solution to the existing issues of Li anodes and potentially paves a technically feasible route for lithium metal batteries.

Meng, Xiangbo↗
DOE OSTI2021

Effect of Cu nanoparticles on the tribological performance of polydopamine + polytetrafluoroethylene coatings in oil-lubricated condition

For this study, the effect of Cu nanoparticles (NPs) on the tribological performance of the thick polydopamine (PDA) + polytetrafluoroethylene (PTFE) coatings in DTE-32 Mobil lubricated condition was investigated. PDA + PTFE + Cu NP coatings with 45 µm thickness were spray-coated with 0.12, 0.25, and 0.50 wt% of Cu NPs in an aqueous PDA + PTFE solution, respectively. The mechanical properties were studied by PeakForce quantitative nanomechanical (PFQNM) characterization and nanoindentation. The Young's modulus increased, and the coefficient of friction (COF) reduced with the addition of Cu NPs compared to PDA + PTFE coating. The PDA + PTFE + 0.25 wt% Cu and PDA + PTFE + 0.50 wt% Cu coatings increased the durability by 52% and 33%, respectively, compared to the coating without Cu NPs. The better tribological performance of the nanocomposite coatings is contributed by the better mechanical properties, better adherence, and enhanced cross-linking between the constituents of the nanocomposite coatings due to the presence of Cu NPs. The addition of 0.25 wt% Cu NPs in PDA + PTFE increased the thermal conductivity by 12%.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Tribological properties of PDA + PTFE coating in oil-lubricated condition

In this work the tribological properties of 45 ± 2 μm-thick polytetrafluoroethylene (PTFE) and polydopamine (PDA) + PTFE coatings in oil-lubricated conditions were investigated under a normal load of 10 N and a linear reciprocating speed of 0.1 m/s. Both the PTFE and the PDA + PTFE coatings were deposited using an in-house spray-coating method. The PDA + PTFE coating was five times more durable compared to the PTFE coating in oil-lubricated conditions. Both PTFE and PDA + PTFE coatings showed lower COF in oil-lubricated conditions than in dry conditions. The nanomechanical properties measured by PeakForce Quantitative Nanomechanical (PFQNM) characterization method showed an increase in Young’s modulus and adhesion force for the PDA + PTFE coatings compared to the PTFE coatings. Chemical analysis showed that the cross-linking between PDA and PTFE polymer chains occurred during the high-temperature sintering procedure. Finally, the higher adhesion of PDA + PTFE coating to the cast iron substrate and the stronger cohesion due to the cross-linking between PDA and PTFE contributed to the higher durability of the PDA + PTFE composite coatings.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Methods of making a component with variable magnetization and related components

A method of forming a component having a variation in saturation magnetization is presented. The method includes selectively diffusing nitrogen into a metallic component of a masked metallic component by exposing the masked metallic component to a nitrogen-rich atmosphere. The masked metallic component includes a patterned oxide layer formed on a surface of the metallic component, and the patterned oxide layer includes an oxide of a metal present in the metallic component. A related component is also presented.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Dual magnetic phase material rings for AC electric machines

An AC electric machine that includes a dual magnetic phase material ring is disclosed. The AC electric machine includes a stator assembly and a rotor assembly positioned within the stator assembly and configured to rotate relative thereto, the rotor assembly comprising a rotor core including a stack of rotor laminations that collectively form the rotor core, the rotor core including a plurality of rotor poles separated by gaps therebetween. The AC electric machine also includes a dual magnetic phase material ring positioned about the stack of rotor laminations, the dual magnetic phase material ring comprising a first ring portion comprising a magnetic portion and a second ring portion comprising a non-magnetic portion.

42 ENGINEERING↗
DOE OSTI2020

Dual Phase Soft Magnetic Laminates for Low-cost, Non/Reduced-Rare-Earth Containing Electrical Machines

To accelerate the mass market adoption of electric drive vehicles, the key technology barriers in electric motors are (1) magnet cost and rare-earth element price volatility; (2) non-rare-earth electric motor performance; and (3) materials property optimization. The goal of this project was to address these barriers by advancing a unique and innovative dual phase soft magnetic material technology and demonstrating the material in a 30-kW synchronous reluctance motor without using any permanent magnet for electric vehicles. Dual phase magnetic materials offer the electric motor designer the ability to locally control the magnetic saturation level in a motor laminate, while at the same time enhancing the mechanical strength of the laminate material, resulting in an enhancement in motor performance and efficiency. Scalable dual phase soft magnetic laminates manufacturing technologies were developed in collaboration with multiple US manufacturers. 1000 lbs of alloy sheet with a thickness of 0.25mm and width of 280 mm was manufactured within the specifications. Batch sizes of up to 240 laminates per run were produced from the alloy sheet. Two prototype motors with dual phase soft magnetic laminates were designed, built, and tested. The major goal of building the subscale prototype as a pathway to develop scalable manufacturing technologies for the dual phase soft magnetic laminates was met. The additional goal of building and testing the subscale prototype in order to validate the calculated performance with the tested motor performance was also met. For the full-scale 30kW continuous power synchronous reluctance motor prototype, the tested performance met the targets in terms of continuous power at the operating speeds up to 8000 rpm. Post-test studies were conducted and the root causes for the discrepancy between the predicted and tested peak power, continuous power at high speed range, and efficiency were identified. Further modeling study showed that the dual phase rotor machine has a 27% higher torque to active weight ratio than an equivalent performance silicon steel rotor machine. Application space and multiple discussions with traction motor and electric vehicle manufacturers for commercialization of the dual phase soft magnetic material technology were identified and conducted. An initial cost model was established based on the developed manufacturing technologies with the US manufacturers. Future paths for further cost reduction were identified, including increasing the market volume by broadening the applications of the dual phase soft magnetic laminate technology for electric machines in other energy sections such as oil & gas, heating, ventilation, and air conditioning (HVAC), and power generation.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2020

Method for forming a nitrogenation barrier and machine formed using a body having the nitrogenation barrier

A method includes forming one or more oxide barrier layers on one or more protected portions of a magnetic, metallic body, and converting one or more unprotected portions of the magnetic, metallic body to a less magnetic material by exposing the magnetic metallic body having the one or more oxide barrier layers formed thereon to nitrogen. One or more protected portions of the magnetic, metallic body that are beneath the one or more oxide barrier layers are not converted to the less magnetic material. The method can be used to form one or more layers of a laminated electric motor.

36 MATERIALS SCIENCE↗