Lithium-ion batteries are powering a revolution in electrification, but the underlying intercalation mechanism at the electrified interface remains poorly understood. Here, we provide experimental and theoretical evidence that lithium intercalation occurs by coupled ion-electron transfer (CIET), in which classical ion transfer from the electrolyte is coupled with quantum-mechanical electron transfer from the electrode to form an ion-electron pair in the reduced state. Current-voltage responses and reaction-limited capacities, corresponding to small and large overpotentials, respectively, were measured for common electrode materials and linked by the theory. The experiments showed universal dependence of the (de-)intercalation rate on Li-ion filling fraction, as well as temperature and electrolyte effects consistent with the theory. These results could be used to guide the design of high-rate battery interfaces that maximize the CIET reaction-limited current.

Lithium-ion batteries change their geometric dimensions during cycling as a macroscopic result of a series of microscale mechanisms, including but not limited to diffusion-induced expansion/shrinkage, gas evolution, growth of solid-electrolyte interphase, and particle cracking. Predicting the nonlinear dimensional changes with mathematical models is critical to the lifetime prediction, health management, and non-destructive assessment of batteries. In this study, we present an approach to implement an elastoplasticity model for powder materials into the porous electrode theory (PET). By decomposing the overall deformation into elastic, plastic, and diffusion-induced portions and using the powder plasticity model to describe the plastic portion, the model can capture the reversible thickness change caused by Li-ion (de-)intercalation as well as the irreversible thickness change due to the rearrangement and consolidation of particles. For real-world applications of the model to predict battery health and safety, the key lies in solving the mathematical equations rapidly. Here, we implemented the coupled model into the open-source software PETLION for millisecond-scale simulation. The computational model is parameterized using values gathered from literature, tested under varying conditions, briefly compared to real-world observations, and qualitatively analyzed to find parameter-output relations.

Nanopore-based sensing platforms have transformed single-molecule detection and analysis. The foundation of nanopore translocation experiments lies in conductance measurements, yet existing models, which are largely phenomenological, are inaccurate in critical experimental conditions such as thin and tightly fitting pores. Of the two components of the conductance blockade, channel and access resistance, the access resistance is poorly modeled. We present a comprehensive investigation of the access resistance and associated conductance blockade in thin nanopore membranes. By combining a first-principles approach, multiscale modeling, and experimental validation, we propose a unified theoretical modeling framework. The analytical model derived as a result surpasses current approaches across a broad parameter range. Beyond advancing our theoretical understanding, our framework's versatility enables analyte size inference and predictive insights into conductance blockade behavior. Our results will facilitate the design and optimization of nanopore devices for diverse applications, including nanopore base calling and data storage.

Interface engineering remains a largely underexplored area and yet it holds the keys to high performance Li-ion batteries. It is the charge transfer across electrode-electrolyte interfaces, its inefficient energetics and sluggish kinetics that are oftentimes significant obstacles for achieving fast charging and high power regimes without compromising battery lifespan. This work propose a Boltzmann-averaged first principles workflow based on constant potential and constrained density functional theory for estimation of atomic scale factors influencing coupled ion-electron charge transfer kinetics across battery electrode-electrolyte interfaces. The approach estimates diabatic Li+ interface energy landscapes as function of the interface character and operational conditions, needed to simulate charging/discharging currents. Experimental trends for the LixCoO2 (0.5≤x≤1.0) electrode in varied organic electrolytes with LiPF6 and LiClO4 salts are reproduced, identifying Li+ transfer energy and Li+ adsorption energy as decisive factors influencing the enhanced kinetics in LiClO4-based electrolytes over LiPF6, rationalized by a stronger surface interaction of ClO4-.

Electrokinetic phenomena within complex structures are relevant in microfluidics. For example, ion concentration polarization is used for electrokinetic trapping for enhanced biosensing using molecular probes1. Concentration polarization near ion-selective membranes also plays an important role in separation systems for desalination2. Aside from microfluidics, electrochemical growth-dissolution phenomenon has been reported in lithium ion battery systems where lithium plating and subsequent growth of dendrites can exacerbate the loss of cyclable lithium through the formation of isolated Lithium (i-Li) islands3. Initially thought to be “dead”, these islands were shown to migrate from one electrode to the other through a deposition-dissolution mechanism3. We present a mathematical solution for the growth and migration of an electrochemically active metal particle in a background current. A broad range of phenomena such as viscous fingering4, diffusion-limited aggregation4 and electrochemical deposition5 follow Laplacian growth and have been traditionally described using conformal map-dynamics in two dimensions. Some non-Laplacian phenomena like electrochemical transport6,7 and advection-diffusion-limited aggregation6 fall into the conformally invariant category8 and can still be simplified using conformal-mapping techniques. Our solution applies conformal mapping to the non-Laplacian growth of the metal particle to evaluate the role of particle morphology in the evolution of the phase boundary. In addition to migration, dissolution-deposition was found to lead to formation of cusps on the phase boundary under certain conditions. The solution is applicable for a general class of problems with a reactive post or particle in an applied background flux. Analytical solutions such as the one presented here are expected to augment numerical simulations and lead to expressions that capture conditions for the onset of morphological instabilities. References S. Park, B. Sabbagh, R. Abu-Rjal, and G. Yossifon, Lab Chip, 22, 814–825 (2022) https://pubs.rsc.org/en/content/articlehtml/2022/lc/d1lc00864a. D. Deng et al., Desalination, 357, 77–83 (2015). F. Liu et al., Nature 2021 600:7890, 600, 659–663 (2021) https://www.nature.com/articles/s41586-021-04168-w. J. Mathiesen, I. Procaccia, H. L. Swinney, and M. Thrasher, Europhys Lett, 76, 257 (2006) https://iopscience.iop.org/article/10.1209/epl/i2006-10246-x. D. A. Kessler, J. Koplik, and H. Levine, http://dx.doi.org/10.1080/00018738800101379, 37, 255–339 (2006) https://www.tandfonline.com/doi/abs/10.1080/00018738800101379. M. Z. Bazant, J. Choi, and B. Davidovitch, Phys Rev Lett, 91, 045503 (2003) https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.91.045503. Z. Gu et al., Phys Rev Fluids, 7, 033701 (2022) https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.7.033701. M. Z. Bazant, Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 460, 1433–1452 (2004) https://royalsocietypublishing.org/doi/10.1098/rspa.2003.1218.