Chemomechanics is an old subject, yet its importance
has been revived
in rechargeable batteries where the mechanical energy and damage associated
with redox reactions can significantly affect both the thermodynamics
and rates of key electrochemical processes. Thanks to the push for
clean energy and advances in characterization capabilities, significant
research efforts in the last two decades have brought about a leap
forward in understanding the intricate chemomechanical interactions
regulating battery performance. Going forward, it is necessary to
consolidate scattered ideas in the literature into a structured framework
for future efforts across multidisciplinary fields. This review sets
out to distill and structure what the authors consider to be significant
recent developments on the study of chemomechanics of rechargeable
batteries in a concise and accessible format to the audiences of different
backgrounds in electrochemistry, materials, and mechanics. Importantly,
we review the significance of chemomechanics in the context of battery
performance, as well as its mechanistic understanding by combining
electrochemical, materials, and mechanical perspectives. We discuss
the coupling between the elements of electrochemistry and mechanics,
key experimental and modeling tools from the small to large scales,
and design considerations. Lastly, we provide our perspective on ongoing
challenges and opportunities ranging from quantifying mechanical degradation
in batteries to manufacturing battery materials and developing cyclic
protocols to improve the mechanical resilience.
Single-crystalline nickel-rich cathodes are a rising candidate with great potential for high-energy lithium-ion batteries due to their superior structural and chemical robustness in comparison with polycrystalline counterparts. Within the single-crystalline cathode materials, the lattice strain and defects have significant impacts on the intercalation chemistry and, therefore, play a key role in determining the macroscopic electrochemical performance. Guided by our predictive theoretical model, we have systematically evaluated the effectiveness of regaining lost capacity by modulating the lattice deformation via an energy-efficient thermal treatment at different chemical states. We demonstrate that the lattice structure recoverability is highly dependent on both the cathode composition and the state of charge, providing clues to relieving the fatigued cathode crystal for sustainable lithium-ion batteries.
Understanding interactions between cell-penetrating peptides and biomembrane under tension can help improve drug delivery and elucidate mechanisms underlying fundamental cellular events. As far as the effect of membrane tension on translocation, it is generally thought that tension should disorder the membrane structure and weaken its strength, thereby facilitating penetration. However, our coarse-grained molecular dynamics simulation results showed that membrane tension can restrain polyarginine translocation across the asymmetric membrane and that this effect increases with increasing membrane tension. We also analyzed the structural properties and lipid topology of the tensed membrane to explain the phenomena. Simulation results provide important molecular information on the potential translocation mechanism of peptides across the asymmetric membrane under tension as well as new insights in drug and gene delivery.
Defects are pervasive in electrochemical systems across multiple length scales. The defect chemistry largely differs from the bulk behavior and often dictates the rate performance for battery materials. However, the impact of material defects on Li kinetics remains elusive because of their complex nature and the sensitivity of the reaction kinetics on the local atomic environment.Here we focus on the grain boundaries (GBs) in layered-oxide cathodes and address their role in Li transport using the firstprinciples theoretical approach. We construct the coincidence site lattices of ∑2(11̅ 04̅ ), ∑3(1̅ 102̅ ), ∑5(11̅ 01̅ ), and ∑9(1̅ 104̅ ) GBs. The energy profiles for Li migration across and along the grain planes are plotted. We discuss in detail how the atomistic features associated with various grain structures such as the local structural distortion and charge redistribution determine the Li transport kinetics. Specifically, the coherent ∑2 GBs facilitate Li migration with 1−2 orders of magnitude increased diffusivity than the bulk diffusion, the asymmetric ∑3 GBs significantly impede Li diffusion, and the locally disordered ∑5 and ∑9 GBs cause slightly increased Li diffusivity at the intermediate diffusion distance (∼15 Å). We further evaluate the overall Li diffusivity and conductivity in the layered-oxide lattice by a distinction of Li transport in the bulk, across the GBs, and along the grain planes. The fundamental understanding sheds insight on a prevalent defect in the state-of-the-art cathode and its potential optimization of Li kinetics.
Nucleic acid lateral flow assays (NALFAs) have attracted much attention due to their rapid, robust, simple, and cost-effective features. However, the current NALFAs are still limited by low sensitivity because of the poor understanding and control of the underlying complex flow and reaction processes. Although enormous efforts have been devoted to enhancing detection sensitivity of NALFAs, developing simple NALFAs with high sensitivity remains difficult. Thus, we proposed a novel physical−chemical coupling method using dissoluble saline barriers and developed the corresponding mathematical model to better understand the underlying processes to enhance the NALFA sensitivity. Through optimizing the design parameters (e.g., saline barriers patterns, volume, and concentrations) experimentally and numerically, we achieved the highest 10-fold sensitivity enhancement for detection of nucleic acids (including HBV, Staphylococcus aureus, and salmonella as model targets) using this method. The physical−chemical coupling method offers a facile strategy for developing highly sensitive NALFAs.
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