The solid-electrolyte interphase (SEI) layer is pivotal for the stable and rechargeable batteries especially under high rate. However, the mechanism of Li+ transport through the SEI has not been clearly...

The aprotic lithium-oxygen (Li-O 2 ) battery has excited huge interest due to its having the highest theoretical energy density among the different types of rechargeable battery. The facile achievement of a practical Li-O 2 battery has been proven unrealistic, however. The most significant barrier to progress is the limited understanding of the reaction processes occurring in the battery, especially during the charging process on the positive electrode. Thus, understanding the charging mechanism is of crucial importance to enhance the Li-O 2 battery performance and lifetime. Here, recent progress in understanding the electrochemistry and chemistry related to charging in Li-O 2 batteries is reviewed along with the strategies to address the issues that exist in the charging process at the present stage. The properties of Li 2 O 2 and the mechanisms of Li 2 O 2 oxidation to O 2 on charge are discussed comprehensively, as are the accompanied parasitic chemistries, which are considered as the underlying issues hindering the reversibility of Li-O 2 batteries. Based on the detailed discussion of the charging mechanism, innovative strategies for addressing the issues for the charging process are discussed in detail. This review has profound implications for both a better understanding of charging chemistry and the development of reliable rechargeable Li-O 2 batteries in the future.

We study the electrical conductance of gold nanoconstrictions by controlling the electrochemical potential. At positive potentials, the conductance is quantized near integer multiples of G0(2e(2)/h) as shown by well-defined peaks in the conductance histogram. Below a certain potential, however, additional peaks near 0.5G(0) and 1. 5G(0) appear in the histogram. The fractional conductance steps are as stable and well defined as the integer steps. The experimental data are discussed in terms of electrochemical-potential-induced defect scattering and Fermi energy shift, but a complete theory of the phenomenon is yet to be developed.

The lithium–sulfur battery is regarded as one of the promising energy‐storage devices beyond lithium‐ion battery due to its overwhelming energy density. The aprotic Li–S electrochemistry is hampered by issues arising from the complex solid–liquid–solid conversion process. Recently, tremendous efforts have been made to optimize the electrochemical reaction in Li–S batteries through rationally designing compositions and structures of cathodes. However, a deep and comprehensive understanding of the actual mechanisms of Li–S batteries and their impact on the performance is still insufficient. The vigorous development of various electrochemical analysis and in situ techniques establish a bridge between the microstructure of components and the macroscopic electrochemical performance, thus providing more scientific guidance for the optimal design of Li–S batteries. In this review, based on insights into the mechanism of aprotic Li–S electrochemistry with the aid of in situ characterization and electrochemical methods, the advanced innovations in optimizing Li–S batteries are systematically summarized, including the materials design, cathode configurations optimization, and electrolyte engineering, with the aim to gain a comprehensive understanding of cathodic redox processes and thus achieve high‐performance Li–S batteries. The current status and possible future directions of the field are accordingly outlined.

Albeit the effectiveness of surface oxygen vacancy in improving oxygen redox reactions in Li–O2 battery, the underpinning reason behind this improvement remains ambiguous. Herein, the concentration of oxygen vacancy in spinel NiCo2O4 is first regulated via magnetron sputtering and its relationship with catalytic activity is comprehensively studied in Li–O2 battery based on experiment and density functional theory (DFT) calculation. The positive effect posed by oxygen vacancy originates from the up shifted antibond orbital relative to Fermi level (Ef), which provides extra electronic state around Ef, eventually enhancing oxygen adsorption and charge transfer during oxygen redox reactions. However, with excessive oxygen vacancy, the negative effect emerges because the metal ions are mostly reduced to low valence based on the electrical neutral principle, which not only destabilizes the crystal structure but also weakens the ability to capture electrons from the antibond orbit of Li2O2, leading to poor catalytic activity for oxygen evolution reaction (OER).

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The state-of-the-art design strategies toward highly active catalytic materials and cathode structures for Li–CO2 batteries are reviewed and discussed.