Imidazolium-based cationic groups of the c-IPN binder increase C/A ratio, trap PF6– from the liquid electrolyte and allow easy Li+ transport across the cathode. Fraction of the solvation structure types in the AEE and dilute aqueous electrolyte (control) at 298 K.
Introduction
Introduction to rechargeable battery electrolytes
31 The electrochemical stability window (ESW) of an electrolyte is determined based on the separation energy (Eg) of the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) of the electrolyte. 80 In the past, most research was focused on the development of materials to improve the ionic conductivity of solid electrolytes.
Introduction to multi-scale molecular simulation
By applying DFT calculations, specific information about thermodynamic properties such as Gibbs free energy of reaction can be predicted. By applying the force field, the potential energy of each atom in the system can be calculated.
Manipulation of Electrolyte Structure
Regulating electrostatic phenomena by cationic polymer binder: Toward scalable
For the n-IPN binder, the RDF of PF6- gradually increased with distance (r) (ie, being further away from the surface of the n-IPN binder) (Fig. 2.1.1a). In comparison, the c-IPN binder showed a distinct peak at r of 5.0 Å, indicating that PF6 predominately exists around the c-IPN surface. The c-IPN cathode showed higher DLi+ than the control n-IPN cathode over the entire voltage range.
Overall, the solvation structures of the c-IPN cathode showed lower HOMO energy levels than those of the n-IPN cathode, indicating that the coordinated complexes close to the c-IPN bond are difficult to oxidize. In the Li solvation structure of 5-0-1, the c-IPN cathode exhibited the lower binding energy with PF6– than the n-IPN cathode, indicating that PF6– is weakly bound to Li+ due to the electrostatic attraction with c-IPN binder. Accordingly, PF6- adjacent to the c-IPN linker is vulnerable to degradation and thus promotes
This theoretical study shows that the different CEI layers between the c-IPN and n-IPN cathodes arise from the formation of different Li+ solvation structures inside the cathodes.
Aqueous eutectic lithium-ion electrolytes for wide-temperature operation
Design of Biphasic Electrolytes applying Kosmotropic Effect
- Introduction
- Computational models and method
- Results and discussion
- Effects of kosmotropic/chaotropic anions on electrolyte structure
- Relationship between electrolyte structure and phase separation
- Biphasic liquid electrolytes for Zn-metal full cells
- Ion transport phenomena at Biphasic liquid electrolytes
- Conclusion
- References
Note that the anion–water interaction energy, water coordination number, and anion–water distance are the average values of the last 2ns of MD trajectories. The MD simulation system to calculate the ionic conduction mechanism of Zn2+ ion transported through the interfacial region of ZBPE electrolyte.
Development of Novel Solid-electrolyte Material
Introduction
Here we demonstrate a Li+-centered G-quadruplex (LiGQ) as a novel strategy for single-ion conduction based on ion-dipole interaction. Moreover, the question of whether proper directional cation migration occurs via 1D central channels formed in the guanine-based G-quadruplexes remains intriguing. In sharp contrast to the traditional single-ion conductors described above with strong ion-ion interactions and long tortuosity, ion transport of the LiGQ is enabled by directional Li+ slip through the one-dimensional (1D) central channels at the microscopic level, making the following possible: (1) interaction with weak ion (Li+) dipole (originating from the cyclic tetramer, G-quartet) and (2) short and clear ionic pathways (Fig. 4.1b).
This unusual Li+ sliding behavior of LiGQ and its self-assembled crystal structure were elucidated through in-depth experimental and theoretical investigations. In addition, we investigate its properties in the presence of various cationic salts (Li+, Na+, K+ and Mg2+), showing the effects of the radius and nature of the coordinating cations on the characteristics of the G-quadruplex structures. The superior transport kinetics of Li+ in the G-quadruplex may open a new window for its potential application in Li batteries as a single-ion conductor. a) Schematic comparison of ion transport phenomena in different ion conductors: traditional conductors vs ideal conductor.
The close stacking of the G quartets in the vertical direction leads to the formation of 1D central channels that allow straightforward Li+ conduction paths in LiGQ.
Ion Slippage through Li + -centered G-quadruplex
Both C8 and N9 substituents lean outside the quartet structure and do not disrupt N3 hydrogen bonding. The structural stability of the LiGQ upon addition of Li salts was investigated by molecular dynamics. Starting from the relaxed structure of the trapped anion system, we removed the Li+ and OTf ions.
We can therefore conclude that the Li+ and OTf ions play a viable role in the structural stability of the LiGQ. a) Relaxed structure of LiGQ with and without Li salts, respectively. The single ion conduction behavior of the LiGQ was investigated by applying an electric field of 2 V nm-1 and analyzing the MSD of Li+ and OTf- ions (Fig. 4.6). The MSD of the Li+ was analyzed in terms of movement direction (along x-, y- and z-axis).
In addition, no additional movement in the x or y direction occurred under varying direction of the electric field (Fig. 4.7c).
G-quadruplex with Various Cations as Single-ion Conductor
Therefore, we first investigated the effect of the valence of the cations on the G-quadruplex structure (Fig. 4.10a). The effect of ionic radius on the coordination properties of the cations in the G-quadruplexes was investigated, as shown in Fig. In the thermodynamically favorable structures, the cations with a small ionic radius (ie Li+, Na+ and Mg2+) are located at the intraplane of the G-quartet and are coordinated by four carbonyl oxygens.
This is because the large ionic radius of the K+ ion causes strong van der Waals repulsion when located at the inner face of the G quartet, which cannot be compensated by electrostatic attraction. From the profiles, the magnitude of the ion migration barrier was as follows: Li+ < Na+ < K+ Mg2+. The cations with a small ionic radius (i.e. Li+, Na+ and Mg2+) are most stable when located at the inner face of the G quartet.
For a deeper understanding of the potential energy surface for ion migration, the relative energy profiles in Figs.
Conclusion
Divalent cation-assisted identification of physicochemical properties of metal ions that stabilize RNA G-quadruplexes. Conserved elements with the potential to form polymorphic G-quadruplex structures in the first intron of human genes. QuadBase: Genome-Wide Database of G4 DNA - Occurrence and Conservation in Humans, Chimpanzees, Mice and Rats and 146 Microbes.
Evolution of the solid-electrolyte interface in carbon anodes visualized by atomic resolution cryogenic electron microscopy. Review of single polymer lithium-ion conductors as an organic route to solid-state lithium-ion and metal batteries. Ab initio molecular dynamics study of the interaction of plutonium with oxygen in the gas phase.
Understanding the Vogel-Fulcher-Tammann law in terms of the fluctuation model of the bond coordination strength number.
Summary and Future Perspectives
Summary
In Chapter 4, we proposed a new single-ion conducting material based on Li+ slip, called Li+-centered G-quadruplex (LiGQ). LiGQs are composed of vertically stacked G-quartets that form continuous Li+ conducting channels in the center while placing counter anions on the outside of the channel through H-bonds with guanine molecules. From MD simulations, LiGQ is predicted to exhibit ion slip behavior, a one-dimensional, single-ion conducting behavior with high tLi+ (~0.91), which represents a promising possibility for LiGQ to be used as a solid electrolyte.
Furthermore, the LiGQ showed a remarkably low Ea for migration and a weak Li+ binding energy, which is expected to exhibit competitive conductivity compared to traditional single-ion conductors. Furthermore, we confirmed that the structure and ion migration barrier of G-quadruplex can be manipulated by controlling the coordinating cations in GQ. Compared with GQs containing other cations (i.e., Na+, Mg+, and K+), LiGQ was expected to exhibit superior conductive properties.
Using a multiscale simulation method, experimental observations were interpreted at the molecular level, providing a fundamental understanding of electrolyte chemistry.
Future Perspectives
These limitations of classical case-by-case simulation can be overcome by using high-throughput screening9 based on high-accuracy calculations with large-scale models that can target accurate electrolytes that meet certain descriptors. Furthermore, the evolving machine learning (ML) techniques provide a new research paradigm to understand the relationship between structure and function based on a huge data set. Various attempts are being made to create a new research approach by fusing ML with multi-scale simulation methods.
For example, parameterization of classical/reactive force fields by machine learning, 10, 11 adoption of machine learning force fields (MLFF) based on neural network model which is completely different from empirical classical force fields, 12, 13 and inverse molecular design using AI. 14 By applying introduced strategies, we expect that rechargeable batteries with safe and high energy density can be developed by tailoring promising electrolytes based on a deep understanding of structure-function relationship and underlying interactions under electrolyte-electrode system.
교수님께서는 제가 연구에 충실해야 한다고 항상 강조하셨고, 연구 과정에서 많은 조언과 도움을 주셨으며, 조화로운 연구실 분위기를 조성해주셔서 제가 성공적으로 학위 과정을 마칠 수 있었던 것은 저에게 큰 축복이었습니다. . 또한 학위과정 동안 많은 공동연구 과제를 제안해주신 이상영 교수님께 감사의 말씀을 전하고 싶습니다. 저는 인턴 시절 이상영 교수님 연구실에서 공동연구를 준비하기 시작했는데, 이는 학위 과정 전반에 걸쳐 수행한 삼성 과제를 통해 시작되었습니다.
이상영 교수 연구실과의 협업을 통해 배터리 전해액을 중심으로 다양한 주제를 연구하면서 시뮬레이션 방법을 적용하는 방법을 배울 수 있었습니다. 이번 연구기회 덕분에 이번 논문을 발표할 수 있었고, 공동연구를 통해 얻은 성과로 올해 최우수 대학원생상을 받을 수 있었습니다. 저에게 다양한 연구 기회와 지도를 해주신 교수님들뿐만 아니라, 힘든 연구실 생활을 견뎌낼 수 있도록 도와주신 연구실 선후배들에게도 감사의 말씀을 전하고 싶습니다.
박사님과 연구실에서 일하면서 직간접적으로 도움을 준 동급생, 후배들. 크리스티노.
