Suppressing High-Current-Induced Phase Separation in Ni-Rich Layered Oxides by Electrochemically Manipulating Dynamic Lithium Distribution.

Understanding the cycling rate-dependent kinetics is crucial for managing the performance of batteries in high-power applications. Although high cycling rates may induce reaction heterogeneity and affect battery lifetime and capacity utilization, such phase transformation dynamics are poorly understood and uncontrollable. In this study, synchrotron-based operando X-ray diffraction is performed to monitor the high-current-induced phase transformation kinetics of LiNi0.6 Co0.2 Mn0.2 O2 . The sluggish Li diffusion at high Li content induces different phase transformations during charging and discharging, with strong phase separation and homogeneous phase transformation during charging and discharging, respectively. Moreover, by exploiting the dependence of Li diffusivity on the Li content and electrochemically tuning the initial Li content and distribution, phase separation pathway can be redirected to solid solution kinetics at a high charging rate of 7 C. Finite element analysis further elucidates the effect of the Li-content-dependent diffusion kinetics on the phase transformation pathway. The findings suggest a new direction for optimizing fast-cycling protocols based on the intrinsic properties of the materials.

Data on the effect of particle size, porosity and discharging rate on the performance of lithium-ion battery with NMC 622 cathode through numerical analysis.

The data presented in this article are related to the computed results reported in the article entitled "A modeling approach to study the performance of Ni-rich layered oxide cathode for lithium-ion battery" [1]. The lithium-ion battery (LIB) employed in the simulation is made up of a LiNi0.6Mn0.2Co0.2O2 (NMC 622) cathode and lithium metal foil anode. The numerical simulations were carried out using COMSOL Multiphysics 5.4 software which is based on the finite element (FE) method. The data presented in this manuscript shows how varying particle size and porosity affect the performance of the battery as the discharging rate is varied. Four different particle sizes and six different porosities were varied for the purpose of understanding the above behavior. The data presented can be used to further the analysis reported in the accompanying manuscript and aid in design of other cathode materials for LIB and other battery systems. It can also be used to compare some measured results for validation purposes. A comprehensive analysis of the data is found in [1].

Modeling of Stresses and Strains during (De)Lithiation of Ni3Sn2-Coated Nickel Inverse-Opal Anodes.

Tin alloy-based anodes supported by inverse-opal nanoscaffolds undergo large volume changes from (de)lithiation during cyclic battery (dis)charging, affecting their mechanical stability. We perform continuum mechanics-based simulation to study the evolution of internal stresses and strains as a function of the geometry of the active layer(s): (i) thickness of Ni3Sn2 single layer (30 and 60 nm) and (ii) stacking sequence of Ni3Sn2 and amorphous Si in bilayers (60 nm thick). For single Ni3Sn2 active layers, a thinner layer displays higher strains and stresses, which are relevant to mechanical stability, but causes lower strains and stresses in the Ni scaffold. For Ni3Sn2-Si bilayers, the stacking sequence significantly affects the deformation of the active layers and thus its mechanical stability due to different lithiation behaviors and volume changes.

Tyrosine-mediated two-dimensional peptide assembly and its role as a bio-inspired catalytic scaffold.

In two-dimensional interfacial assemblies, there is an interplay between molecular ordering and interface geometry, which determines the final morphology and order of entire systems. Here we present the interfacial phenomenon of spontaneous facet formation in a water droplet driven by designed peptide assembly. The identified peptides can flatten the rounded top of a hemispherical droplet into a plane by forming a macroscopic two-dimensional crystal structure. Such ordering is driven by the folding geometry of the peptide, interactions of tyrosine and crosslinked stabilization by cysteine. We discover the key sequence motifs and folding structures and study their sequence-specific assembly. The well-ordered, densely packed, redox-active tyrosine units in the YYACAYY (H-Tyr-Tyr-Ala-Cys-Ala-Tyr-Tyr-OH) film can trigger or enhance chemical/electrochemical reactions, and can potentially serve as a platform to fabricate a molecularly tunable, self-repairable, flat peptide or hybrid film.

Analysis of transformation plasticity in steel using a finite element method coupled with a phase field model.

An implicit finite element model was developed to analyze the deformation behavior of low carbon steel during phase transformation. The finite element model was coupled hierarchically with a phase field model that could simulate the kinetics and micro-structural evolution during the austenite-to-ferrite transformation of low carbon steel. Thermo-elastic-plastic constitutive equations for each phase were adopted to confirm the transformation plasticity due to the weaker phase yielding that was proposed by Greenwood and Johnson. From the simulations under various possible plastic properties of each phase, a more quantitative understanding of the origin of transformation plasticity was attempted by a comparison with the experimental observation.