The loss of sulfur in the cathode of a lithium sulfur battery (LSB) severely hinders the practical application of LSBs, and so do the insulativity of S and its lithiation end products. The incorporation of MXene can significantly improve the performance of LSBs; however, the underlying mechanism at the atomic scale has not been deeply explored. In the present work, by using density functional theory calculations, we systemically studied the interactions of lithium (poly)­sulfides (Li2S m ) on Ti-based bare MXenes (Ti n X n–1) and surface functionalized Ti2C with −F, −O, and −OH groups. Through analyzing the geometric and electronic structures, binding energies, and deformation charge densities of Li2S m adsorbed MXenes, we found that the strong Ti–S bonds dominate the interactions between Li2S m and MXenes. The strong Coulombic interactions help cathodes to confine S from dissolution. Besides, the conductivities of MXenes and Li2S m @MXenes are beneficial for the overall performance of the LSB. These will provide in-depth theoretical guidance support for the utilization of MXene in LSBs.

The unipolar resistive switches are investigated in silicon highly rich SiOx (x < 0.75) films. The as-deposited SiO0.73 films contain high concentration (1.0 × 1019 cm−3) of silicon dangling bonds (Si-DBs) and are rich in SiO2≡Si–Si and O3≡Si–Si configurations. Unlike the currently reported normal silicon-rich SiOx (x > 1.8) based devices, our Pt/SiO0.73/Pt devices operate at lower voltage regime (<2.0 V) and exhibit much lower resistance (∼30 Ω). The reset voltage (∼0.7 V) is lower than set voltage (∼1.7 V) and the performance is reduced in the vacuum environment. We propose a Si-DBs percolation model to explain the above characteristics. The experimental evidences for supporting our model are presented and discussed.

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