Article
Polymer Science
Praveenkumar Sappidi, Xiaoyang Liu, Kathryn E. O'Harra, Jason E. Bara, C. Heath Turner
Summary: Molecular dynamics simulations and complementary experiments were used to study the inter- and intramolecular structures and conformational properties of imidazolium ionenes in an ionic liquid. Different chemical and structural variations of the polymers were found to affect their internal interactions and interactions with surrounding molecules, resulting in changes in chain flexibility and alignment of imidazolium groups. The concentration of alkyl groups and polymer architecture also play important roles in determining the polymer structure and properties.
Article
Chemistry, Physical
Martin Otero-Lema, Pablo Martinez-Crespo, Trinidad Mendez-Morales, Hadrian Montes-Campos, Luis M. Varela
Summary: In this paper, classical Molecular Dynamics simulations were used to study the interfacial structure of two ternary mixtures based on protic and aprotic ionic liquids. The simulations revealed the evolution of density profiles and the adsorption behavior of ions at charged interfaces. The results also showed the formation of a dense layer of solvent molecules at the interface. The influence of hydrogen bonds in differentiating between protic and aprotic mixtures was highlighted.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Chemistry, Multidisciplinary
Junze Guo, Weidong Zhang, Zeyu Shen, Shulan Mao, Xinyang Wang, Shichao Zhang, Jiahui Zhang, Yingying Lu
Summary: Poly(ethylene oxide) (PEO) based solid-state electrolytes show potential for practical all solid-state Li-metal batteries (ASSLMBs) due to their good chemical stability. However, the use of thin PEO presents a risk of short circuit in its semi-molten state, and PEO can be oxidatively decomposed by cathodes under high voltage, hindering the practical application of PEO-based ASSLMBs. In this study, the introduction of Nanodiamonds (NDs) into PEO electrolytes is found to greatly improve the electrochemical performance of PEO-based batteries by readjusting the Li+ and e(-) conductivity at the anode/cathode interface.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Correction
Chemistry, Physical
Yury A. Budkov, Nikolai N. Kalikin, Andrei L. Kolesnikov
Summary: The correction for 'Electrochemistry meets polymer physics: polymerized ionic liquids on an electrified electrode' by Yury A. Budkov et al. published in Phys. Chem. Chem. Phys., 2022, DOI: 10.1039/d1cp04221a addresses any errors in the original article.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Huamei Yang, Ju Jiang, Bingzhe Zhang, Wenyuan Zhang, Weining Xie, Jing Li
Summary: This study investigates the effect of [BMIM]HSO4/ethanol pretreatment on the thermal behavior of undissolved cellulose. The results show that the pretreatment effectively lowers the thermal stability of cellulose and promotes its thermal decomposition at low temperature.
Article
Chemistry, Physical
Beichen Liu, Wenxiao Guo, Matthew A. Gebbie
Summary: In this study, we investigate the influence of ionic correlations on the reaction rates and selectivity of CO2 electroreduction. Through experiments, we find that at intermediate concentrations, the reduction rates of CO2 are accelerated and the efficiency of CO production is enhanced. The acceleration of CO2 reduction is due to the amplification of potential-dependent driving forces, rather than changes in onset potential. These findings are applicable to both cocatalytic and noncatalytic ions.
Article
Chemistry, Physical
Chandrakant Mukesh, Shokat Sarmad, Ajaikumar Samikannu, Dariush Nikjoo, William Siljebo, Jyri-Pekka Mikkola
Summary: In this study, porous ionic liquids (ILs) utilizing microporous ZIF-8 moieties and functional ILs were prepared and thoroughly characterized. The prepared porous ILs exhibited low viscosity, high thermal stability, and reusability, and showed enhanced CO2 sorption capacity compared to neat ILs.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Chemistry, Physical
Muhammad Adnan Naseer, Muhammad Khurram Tufail, Sun Zheng, Chengzhi Wang, Hai-Bo Jin
Summary: To improve the conductivity of LLZO, a novel garnet-type solid electrolyte Li7+xLa3Zr2-xEuxO12 (0 ≤ x ≤ 0.20) with Eu3+ doping was synthesized. Density functional theory (DFT) calculation showed that Eu3+ doping enhanced Li+-ion transport by increasing Li+-ion occupancy at 96h position, resulting in reduced diffusion barrier and enhanced ionic conductivity. The LLZEO solid electrolyte with composition Li7.15La3Zr1.85Eu0.15O12 exhibited the highest ionic conductivity of 0.415 x 10-4 S/cm and the lowest activation energy of 0.28 eV at 25 degrees C. Moreover, a flexible composite electrolyte membrane using LLZEO as filler showed excellent flexibility and high ionic conductivity of 0.15 x 10-4 S/cm at 25 degrees C, making it a promising candidate for ASSLBs.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Engineering, Chemical
Chenlu Wang, Guangyong Liu, Renqiang Cao, Yu Xia, Yanlei Wang, Yi Nie, Chao Yang, Hongyan He
Summary: This study investigates the wetting processes of Li+-doped ionic liquids (ILs) on a TiO2-B(10 0) surface using molecular dynamics simulation. The results show that the doping of Li+ changes the orientation of ILs, weakens the ILs-substrate interaction, and significantly slows down the wetting process. As the Li+ concentration increases, the contact angle increases, indicating a transition from hydrophilic to hydrophobic behavior. On the other hand, heating reduces the contact angle. These results demonstrate that the strong adsorption of Li+ at the interface dominates the wetting process of Li+-doped ILs.
CHEMICAL ENGINEERING SCIENCE
(2023)
Article
Polymer Science
Heewoon Shin, Jowon Shin, Ryan C. Hayward, Hyeong Jun Kim
Summary: Ionoelastomers, consisting of cross-linked networks of polymerized ionic liquids, have unique electrochemical properties. This study investigates the structure of the electric double layer (EDL) at electrified surfaces of IEs and finds that the capacitance of fixed ions is lower than that of counterions in both polyanion and polycation IEs, resulting in an asymmetric capacitance response depending on the applied voltage. The elastic energy of the cross-linked networks restricts the rearrangement of polymeric ions at the electrified surfaces, thereby reducing the EDL capacitance.
Article
Chemistry, Physical
Sulafa Abdalmageed Saadaldeen Mohammed, Wan Zaireen Nisa Yahya, Mohamad Azmi Bustam, Md Golam Kibria, Asiah Nusaibah Masri, Nurul Diyana Mohd Kamonwel
Summary: Ionic liquids (ILs) as electrolytes have unique properties and have attracted attention. This study experimentally evaluated the reduction potentials of five ILs and investigated the parameters that affect their reduction stability. It was found that considering the molecular interaction is crucial for predicting the reduction stability, rather than solely relying on the individual energy levels of the cations or anions.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Chemistry, Multidisciplinary
Junda Huang, Jian He, Quanhui Liu, Jianmin Ma
Summary: Realizing uniform Li+ flow is crucial for achieving even Li deposition in lithium metal batteries (LMBs). In this study, a dynamic ion sieve concept is proposed, which involves designing a buffer layer near the Li anode surface to regulate Li+ spatial arrangement by introducing TMPB into the carbonate electrolyte. The buffer layer induced by TMP+ allows solvated Li+ sufficient time to redistribute and accumulate on the Li anode surface, resulting in a uniform and concentrated Li+ flow. Additionally, TFSI- participates in the formation of an inorganic-rich solid electrolyte interphase (SEI) with Li3N, enhancing the Li+ conductivity of the SEI. As a result, the stable and uniform Li deposition achieved excellent cycling performance in Li||Li symmetric cells for up to 1000 hours at 0.5 mA cm(-2). Furthermore, the Li||NCM622 full cell exhibited excellent cycling stability with a high-capacity retention rate of 66.7% after 300 cycles.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Yichao Cai, Qiu Zhang, Yong Lu, Zhimeng Hao, Youxuan Ni, Jun Chen
Summary: The Li+ transport ability of TFSI-IL electrolyte was greatly enhanced by introducing hydrofluoroether and optimizing electrolyte component ratios, resulting in robust Li deposition and significantly improved cycling stability of Li-O-2 batteries.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Materials Science, Ceramics
Masahide Kaneko, Kakeru Ninomiya, Tomoko Hishida, Yuki Takeuchi, Kazushi Otani, Maiko Nishibori
Summary: The conductivity enhancement of Li7La3Zr2O12 (LLZO), an oxide-based solid electrolyte with excess Li, was investigated experimentally through subvalent cation substitution. Sr-substituted Li-rich LLZO with high conductivity of the order of 10(-4) S/cm was prepared using a solid-state method. Detailed structural analysis through Sr K-edge X-ray absorption near edge spectroscopy, X-ray diffraction, and neutron powder diffraction analyses revealed that the conductivity enhancement is a result of the change in Li+ arrangement caused by the incorporation of excess Li into the LLZO lattice.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2023)
Article
Chemistry, Physical
Beichen Liu, Wenxiao Guo, Matthew A. Gebbie
Summary: This study investigates the influence of ionic correlations on CO2 electrochemical reduction. The findings show that increasing ion concentration leads to an acceleration of CO2 reduction rates and an enhancement of the efficiency to produce CO. Importantly, the acceleration of CO2 reduction is due to the amplification of potential-dependent driving forces. This phenomenon is observed across different types of ions.
Article
Chemistry, Physical
Dmitrii Rakov, Meisam Hasanpoor, Artem Baskin, John W. Lawson, Fangfang Chen, Pavel Cherepanov, Alexandr N. Simonov, Patrick C. Howlett, Maria Forsyth
Summary: By modifying the composition of ionic liquid electrolyte and cycling conditions, the cycling performance and deposition morphology of lithium metal anodes can be improved.
CHEMISTRY OF MATERIALS
(2022)
Article
Chemistry, Physical
Tyler D. Stoffel, Justin B. Haskins, John W. Lawson, Sergiy Markutsya
Summary: In this study, coarse-grained models of ionic liquids were developed from atomistic molecular dynamics systems and corrected using new methods to match experimental data. The developed models of ionic liquids exhibited a unique multilayer ordering at vacuum interfaces.
JOURNAL OF PHYSICAL CHEMISTRY B
(2022)
Article
Engineering, Chemical
Chang Woon Jang, J. Wayne Mullinax, Jin Ho Kang, Frank L. Palmieri, Tyler B. Hudson, John W. Lawson
Summary: The material behavior of API-60 epoxy resin was investigated using atomistic molecular dynamics simulations. A hybrid, reactive force field (M-GAFF2) was developed to understand its elastic/plastic response. The study revealed that elastic deformation was caused by epoxy network rearrangement, while plastic deformation occurred after the yield point by stretching and breaking covalent bonds. M-GAFF2 effectively revealed the ductile-like deformation and failure behavior of the epoxy polymer at the microscopic level. The feasibility of M-GAFF2 under different thermodynamic constraints was verified by evaluating the tensile properties at different temperatures and degree of cure.
POLYMER ENGINEERING AND SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Jacob P. Tavenner, Mikhail I. Mendelev, John W. Lawson
Summary: We have implemented a kinetic Monte Carlo (kMC) algorithm in the widely used MD simulation software, LAMMPS, to overcome the limitations of traditional MD simulations in large-scale diffusion processes. The validation of the MD/kMC algorithm is done by reproducing results obtained from diffusion equations. Comparisons between a traditional Monte Carlo approach and the kMC algorithm are made for the case of L12 phase growth in Ni-Al alloys, demonstrating the unique advantages of the kMC approach for unlocking new capabilities in MD simulations.
COMPUTATIONAL MATERIALS SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Gabriel Plummer, Mikhail I. Mendelev, John W. Lawson
Summary: The mechanism of austenite-martensite interface migration plays a key role in understanding phase transformations and hysteresis in shape memory alloys. Molecular dynamics simulations have the potential to study these transformations in detail, but the timescales involved prevent the observation of interface formation near the transformation temperature. To overcome this challenge, a simulation methodology is presented where steady-state austenite-martensite interfaces are allowed to form close to equilibrium. These interfaces contain well-defined structures that can be perturbed to study their migration. In NiTi alloys, the interfaces are semicoherent and composed of terrace planes separated by structural disconnections. Interface migration occurs through the movement of disconnections, providing an atomic-scale mechanism. The methodology and results presented here lay a foundation for utilizing molecular dynamics simulations to further understand how the atomic-scale structure of austenite-martensite interfaces influences macroscopic properties like hysteresis in shape memory alloys.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Shreyas J. Honrao, Othmane Benafan, John W. Lawson
Summary: Shape memory alloys, especially binary NiTi, are widely used in various industries due to their favorable properties. NASA researchers have compiled a comprehensive database of shape memory properties of multi-component Ni-Ti alloys, which we utilize to train machine learning models to predict shape memory behavior. The models exhibit low errors and can be used for designing new alloys.
SHAPE MEMORY AND SUPERELASTICITY
(2023)
Article
Chemistry, Physical
Kristian B. Knudsen, Pedro L. Arrechea, Rocco P. Viggiano, Donald A. Dornbusch, J. Wayne Mullinax, Charles W. Bauschlicher Jr, Justin B. Haskins, Baochau Nguyen, John W. Lawson, Bryan D. McCloskey
Summary: Nonaqueous Li-O2 batteries have potential for electrification, but suffer from irreversible reactions due to aggressive chemical environment. Linear and cyclic amides and ureas show slight increase in reversibility compared to glymes, but not enough for rechargeable system. Insights into degradation pathways provided using quantitative differential electrochemical mass spectrometry, acid titrations, and isotopic labeling of O2 and carbon.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Physical
J. Wayne Mullinax, Charles W. Bauschlicher Jr, Kristian B. Knudsen, Pedro L. Arrechea, Rocco P. Viggiano, Donald A. Dornbusch, Justin B. Haskins, Baochau Nguyen, Bryan D. McCloskey, John W. Lawson
Summary: In this study, potential decomposition mechanisms of amide and urea solvents were investigated using density functional theory (DFT). Proton and hydrogen abstraction reactions were examined, and the preferred abstraction sites were identified. It was found that the N-H bond of secondary amides and the α-hydrogen atoms were more susceptible to proton abstraction. Additionally, hydrogen abstraction was more favorable at the N-alkyl substituents and α-hydrogen atoms, resulting in the formation of secondary and tertiary radicals. The presence of a coordinating Li+ ion affected the proton abstraction energies, but not the hydrogen abstraction energies. The study also examined the initial steps of a Baeyer-Villiger oxidation type mechanism and found that barriers for these steps were lower with HO2- as the oxidant compared to LiO2-. A comparison with previous experimental results indicated that no single reaction could be identified as the rate-limiting step for predicting the performance of these solvents in Li-O-2 batteries.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Multidisciplinary Sciences
Timothy M. Smith, Christopher A. Kantzos, Nikolai A. Zarkevich, Bryan J. Harder, Milan Heczko, Paul R. Gradl, Aaron C. Thompson, Michael J. Mills, Timothy P. Gabb, John W. Lawson
Summary: We developed a new oxide-dispersion-strengthened NiCoCr-based alloy, GRX-810, using a model-driven alloy design approach and laser-based additive manufacturing. This alloy shows significant improvements in strength, creep performance, and oxidation resistance compared to traditional polycrystalline wrought Ni-based alloys.
Article
Engineering, Mechanical
Valery V. Borovikov, Mikhail I. Mendelev, Timothy M. Smith, John W. Lawson
Summary: MD simulations show that a different mechanism for twin nucleation and growth can compete with the Kolbe mechanism in the temperature range of 600-800 degrees C.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Nanoscience & Nanotechnology
Valery V. Borovikov, Mikhail I. Mendelev, Timothy M. Smith, John W. Lawson
Summary: This study presents the first molecular dynamics simulation of the Kolbe mechanism, revealing that atomic diffusion-mediated reordering occurs in a highly concerted manner, directly influenced by the propagation of dislocations.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
Junsoo Park, Zhigang Wu, John W. Lawson
Summary: The electronic mobility and conductivity of S1-xSex were calculated from first principles, showing that with Se alloying, the mobility initially decreases before increasing towards the Se end. Electron transport exhibits a mixture of quantum motion and temperature-activated hopping behavior, transitioning to temperature-activated around x = 0.50. Intrinsic electron conductivity increases monotonically with x, benefiting at most by an order of magnitude up to x = 0.25.
ACS MATERIALS LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Zhigang Wu, John W. Lawson
Summary: This study reports on the unresolved problems and proposed solutions when using the ab initio approach to study NiTi alloys. The results show that including the electronic free energy in the Gibbs free energy calculations significantly reduces errors in martensitic transition temperatures and resolves controversies on the ground state of NiTi. Additionally, it is discovered that the martensitic transition path in stoichiometric NiTi is directly from B2 to B19' without intermediate phases.