Browsing by Author "Wu, Linmin"

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    Ab initio study of anisotropic mechanical properties of LiCoO2 during lithium intercalation and deintercalation process
    (Office of the Vice Chancellor for Research, 2016-04-08) Wu, Linmin; Zhang, Jing
    The mechanical properties of LixCoO2 under various Li concentrations and associated anisotropy have been systematically studied using the first principles method. During the lithium intercalation process, the Young's modulus, bulk modulus, shear modulus, and ultimate strength increase with increasing lithium concentration. Strong anisotropy of mechanical properties between a-axis and c-axis in LixCoO2 is identified at low lithium concentrations, and the anisotropy decreases with increasing lithium concentration. The observed lithium concentration dependence and anisotropy are explained by analyzing the charge transfer using Bader charge analysis, bond order analysis, and bond strength by investigating partial density of states and charge density difference. With the decrease of Li concentration, the charge depletion in the bonding regions increases, indicating a weaker Co-O bond strength. Additionally, the Young's modulus, bulk modulus, shear modulus, and toughness are obtained by simulating ab initio tensile tests. From the simulated stress-strain curves, LixCoO2 shows the highest toughness, which is in contraction with Pugh criterion prediction based on elastic properties only.
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    Ab initio study of anisotropic mechanical properties of LiCoO2 during lithium intercalation and deintercalation process
    (AIP, 2015-12) Wu, Linmin; Zhang, Jing; Department of Mechanical Engineering, School of Engineering and Technology
    The mechanical properties of LixCoO2 under various Li concentrations and associated anisotropy have been systematically studied using the first principles method. During the lithium intercalation process, the Young's modulus,bulk modulus,shear modulus, and ultimate strength increase with increasing lithium concentration. Strong anisotropy of mechanical properties between a-axis and c-axis in LixCoO2 is identified at low lithium concentrations, and the anisotropy decreases with increasing lithium concentration. The observed lithium concentration dependence and anisotropy are explained by analyzing the charge transfer using Bader charge analysis, bond order analysis, and bond strength by investigating partial density of states and charge density difference. With the decrease of Li concentration, the charge depletion in the bonding regions increases, indicating a weaker Co-O bond strength. Additionally, the Young's modulus,bulk modulus,shear modulus, and toughness are obtained by simulating ab initio tensile tests. From the simulated stress-strain curves, LixCoO2 shows the highest toughness, which is in contraction with Pugh criterion prediction based on elastic properties only.
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    Abrasive Resistant Coatings—A Review
    (MDPI, 2014-05-21) Wu, Linmin; Guo, Xingye; Zhang, Jing; Mechanical Engineering, School of Engineering and Technology
    Abrasive resistant coatings have been widely used to reduce or eliminate wear, extending the lifetime of products. Abrasive resistant coatings can also be used in certain environments unsuitable for lubrications. Moreover, abrasive resistant coatings have been employed to strengthen mechanical properties, such as hardness and toughness. Given recently rapid development in abrasive resistant coatings, this paper provides a review of major types of abrasive coatings, their wearing mechanisms, preparation methods, and properties.
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    Additive Manufacturing of Metallic Materials: A Review
    (Springer, 2017) Zhang, Yi; Wu, Linmin; Guo, Xingye; Kane, Stephen; Deng, Yifan; Jung, Yeon-Gil; Lee, Je-Hyun; Zhang, Jing; Mechanical Engineering, School of Engineering and Technology
    In this review article, the latest developments of the four most common additive manufacturing methods for metallic materials are reviewed, including powder bed fusion, direct energy deposition, binder jetting, and sheet lamination. In addition to the process principles, the microstructures and mechanical properties of AM-fabricated parts are comprehensively compared and evaluated. Finally, several future research directions are suggested.
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    Designing a Low-cost, Light-weight Electric Snowmobile
    (Office of the Vice Chancellor for Research, 2015-04-17) Baharuddin, Fatin; Chen, Guiming; Chen, Yu-Ren; Gandhi, Bhavesh Vijay; Mohammed, Samad Abdul; Wible, Grant; Wu, Linmin; Yong, Zhen Wei; Zhang, Yi; Golub, Michael; Zhang, Jing
    The Indiana University-Purdue University, Indianapolis Jaguar team is participating in the 2015 SAE Clean Snowmobile Challenge (CSC) with the aim of achieving a low-cost snowmobile that weigh less than 200 kg (441 lb). It was re-engineered to be an environmental friendly snowmobile without forgetting to improve the towing capability and less noise. We are using the Phantom Snowmobile PD250LT that is manufactured by FMC Motor Company and sold through out North America. The modified NetGain WarP 7 DC-series motor is connected directly to the sprocket shaft using a Goodyear Synchronous Belt. The belt itself is very quiet and can produce less than 59 dB.
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    Finite element study of Li diffusion and stress in LiNi0.33Mn0.33Co0.33O2 cathode using microstructures reconstructed by synchrotron X-ray tomography
    (Office of the Vice Chancellor for Research, 2016-04-08) Wu, Linmin; Zhang, Yi; Zhang, Jing
    LiNi0.33Mn0.33Co0.33O2 is a good substitute for LiCoO2 because of its good thermal stability and high energy density. In this study, the diffusion and stress in LiNi0.33Mn0.33Co0.33O2 cathode with realistic three-dimensional (3D) microstructures have been studied systematically. Synchrotron Xray tomography was used to obtain the 3D reconstructions of porous LiNi0.33Mn0.33Co0.33O2 microstructures. Li concentration distributions under various C-rates were investigated. The obtained charge/discharge curves under various C-rates were compared with the results from Newman’s model. The stress generation in the cathode was computed coupled with the diffusion. The hydrostatic stress, shear stress and von Mises stress in the particles were analyzed. The results show that the von Mises stress in particle boundaries is higher than the stress inside the particle due to the Li concentration gradient during discharge, which is consistent with the literature. Additionally, the von Mises stress near the particle contact region is much higher than other areas.
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    First principles study on the electrochemical, thermal and mechanical properties of LiCoO2 for thin film rechargeable battery
    (2014) Wu, Linmin; Hoh Lee, Weng; Zhang, Jing
    Thin film rechargeable battery has become a research hotspot because of its small size and high energy density. Lithium cobalt oxide as a typical cathode material in classical lithium ion batteries is also widely used in thin film rechargeable batteries. In this work, the electrochemical, mechanical and thermal properties of LiCoO2 were systematically investigated using the first principles method. Elastic constants under hydrostatic pressures between 0 to 40 GPa were computed. Specific heat and Debye temperature at low temperature were discussed. Thermal conductivity was obtained using the imposed-flux method. The results show good agreements with experimental data and computational results in literature.
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    In Situ Temperature Evolution and Failure Mechanisms of LiNi0.33Mn0.33Co0.33O2 Cell under Over-Discharge Conditions
    (ECS, 2018-09) Wu, Linmin; Liu, Yadong; Cui, Yi; Zhang, Yi; Zhang, Jing; Mechanical Engineering, School of Engineering and Technology
    In this work, in situ study of commercial 18650 NMC (LiNi0.33Mn0.33Co0.33O2) cells under over-discharge charge conditions (100%, 110%, and 120%) has been performed. Both voltage and cell skin temperature evolutions were simultaneously monitored in situ during discharge process. The results show that there is a clear correlation between the voltage and temperature. For the NMC cell under 120% over-discharge condition, the cell failed after only 1 cycle. The voltage dropped to negative values at the end of the discharge. The skin temperature at the end of discharge increased dramatically to 73°C, indicating strong exothermal reactions happened inside the cell. For the 110% over-discharged cell, the cell failed after 10 cycles. The voltage at the end of the discharge process became negative after the 1st cycle. The cell skin temperature increased from 23.2°C to 61.7°C. The peak temperature in each cycle kept increasing until failure. These implies the micro short circuits were developed during the charge-discharge process. The failed components were examined by SEM/EDX and XRD. The results show substantial aluminum exists inside the failed separators. The results suggest that during the over-discharge process, the alumina inside the separator was reduced to aluminum. The electrons migrate through aluminum channel, leading to the failure of the cells.
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    Modeling Nanomaterials in Lithium Ion Battery with Experimental Validation
    (Office of the Vice Chancellor for Research, 2015-04-17) Johnson, Chanel; Hammans, Andrea; Hurtman, James; Clyde, David; Wu, Linmin; Jung, Yeon-Gil; Zhang, Jing
    A lithium-ion battery (Li-ion battery or LIB) is a rechargeable battery type in which lithium ions move from the negative electrode to the positive electrode during discharge and back when charging. Lithium systems are of considerable interest due to their high energy density and low toxicity compared to other rechargeable lithium battery chemistries. Conventional Lithium-ion battery materials typically start as 10-50 micron sized particles. In many of these new chemistries, having the materials in nanoparticle form or as a nanostructured particle or film is critical to achieving the desired performance. The goal of this study is to understand the mechanisms that govern the size-dependence of electrochemical properties and mechanical properties of nanomaterials in Lithium ion batteries using first principles method. We have been developing computational models of LiCoO2 crystals. The specific objectives of the MURI project are to: (1) conduct first principles study of the electrochemical properties and mechanical properties of nanosize LiCoO2; (2) investigate Li ion diffusion phenomena in the nanomaterial; and (3) experimentally validate the computational results.
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    Molecular Dynamics Simulation of Electrical Resistivity in Sintering Process of Nanoparticle Silver Inks
    (Elsevier, 2016-12) Zhang, Yi; Wu, Linmin; Guo, Xingye; Jung, Yeon-Gil; Zhang, Jing; Department of Mechanical Engineering, School of Engineering and Technology
    A molecular dynamics (MD) model is developed to simulate low temperature sintering of silver nanoparticles and resultant resistivity. Due to the high surface to volume ratio, nanoparticle silver inks can sinter at low thermal curing temperatures, which are used in intense pulsed light (IPL) sintering process. In this study, the configurational change of nanoparticle silver during sintering is studied using the MD model. Then the resultant electric resistivity is calculated using the Reimann-Weber formula. The simulation results show that the resistivity decreases rapidly in the initial sintering stage, due to the fast neck formation and growth. Additionally, the predicted temperature-dependent resistivity evolutions are in good agreement with both experimental measurements and analytical sintering model, indicating that the resistivity decreases with increasing sintering temperature. The model provides a design tool for optimizing IPL process.