Heterogeneous Effects on Chemo-Mechanical Coupling Behaviors at the Single-Particle Level

Understanding and alleviating the chemo-mechanical degradation of silicon anodes is a formidable challenge due to the large volume change during operations. Here, for a comprehensive understanding of heterogeneous effects on chemo-mechanical behaviors at the single-particle level, in-situ observation of single-crystalline silicon micropillar electrodes under the inhomogeneous extrinsic conditions, taken as an example, was made. The observation shows that the anisotropic deformation patterns and fracture starting sites are reshaped with the combination of the inhomogeneous electrochemical driving force for charge transfer at the interface between the silicon micropillar and the electrolyte, and crystal orientation-dependent lithiation dynamics. Also, the numerical simulation unravels the underlying mechanisms of deformation and fracture behaviors, and well predicts the relative depth of lithiation at the time of crack initiation under heterogeneous conditions. The results show that heterogeneities arising from extrinsic conditions may induce inhomogeneous mechanical damage and tailor lithiation degree at an active particle level, offering insights into designing large-volume-change battery particles with good mechanical integrity and electrochemical performance under heterogeneous impacts.

Iron group nuclei electron capture in super-Chandrasekhar superstrong magnetic white dwarfs

Using the theory of relativistic mean-field effective interactions, the influences of superstrong magnetic fields (SMFs) on electron Fermi energy, binding energy per nucleus and single-particle level structure are discussed in super-Chandrasekhar magnetic white dwarfs. Based on the relativistical SMFs theory model of Potekhin et al., the electron chemical potential is corrected in SMFs, and the electron capture (EC) of iron group nuclei is investigated by using the Shell-Model Monte Carlo method and Random Phase Approximation theory. The EC rates can increase by more than three orders of magnitude due to the increase of the electron Fermi energy and the change of single-particle level structure by SMFs. However, the EC rates can decrease by more than four orders of magnitude due to increase of the nuclei binding energy by SMFs. We compare our results with those of FFNs (Fuller et al.), AUFDs (Aufderheide et al.) and Nabi (Nabi et al.). Our rates are higher by about four orders of magnitude than those of FFN, AUFD and Nabi due to SMFs. Our study may have important reference value for subsequent studies of the instability, mass radius relationship, and thermal and magnetic evolution of super-Chandrasekhar magnetic white dwarfs.