With the rapid popularization and development of lithium-ion batteries, associated safety issues caused by the use of flammable organic electrolytes have drawn increasing attention. To address this, solid-state electrolytes have become the focus of research for both scientific and industrial communities due to high safety and energy density. Despite these promising prospects, however, solid-state electrolytes face several formidable obstacles that hinder commercialization, including insufficient lithium-ion conduction and surge transfer impedance at the interface between solid-state electrolytes and electrodes. Based on this, this review will provide an introduction into typical lithium-ion conductors involving inorganic, organic and inorganic-organic hybrid electrolytes as well as the mechanisms of lithium-ion conduction and corresponding factors affecting performance. Furthermore, this review will comprehensively discuss emerging and advanced characterization techniques and propose underlying strategies to enhance ionic conduction along with future development trends.

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LiÀ O 2 batteries that can deliver extremely high energy density have attracted worldwide attention. However, the practical use of this promising technology is hindered by an unsatisfactory cycling life and inferior energy efficiency (high discharge/charge voltage gap), although significant progress has been made in this area in the last decade. Recent reports indicate that soluble catalysts or redox mediators dissolved in aprotic electrolytes can catalyze Li 2 O 2 decom-position and reduce the voltage gap between O 2 reduction reaction and O 2 evolution reaction. Here, a specific review on a series of suitable soluble catalysts for LiÀ O 2 batteries is provided. This review will highlight the underpinning chemistry and electrochemistry mechanisms of LiÀ O 2 batteries, as well as the recent progress and challenges of soluble catalysts, with the aim of motivating researchers to further explore applications in LiÀ O 2 cells and other energy storage and conversion systems.

Synthesizing kinetically stable coordination polymers (CPs) through ligand functionalization can effectively improve their supercapacitive performances. Herein, we have successfully synthesized three novel and topological Co-CPs by varying the flexible N-donor ligand and inorganic anions, namely, interpenetrated [Co(HTATB)( o-bib)]·HO, extended two-dimensional (2D) layered Co(HTATB)( m-bib)·2HO, and three-dimensional (3D) Co(HTATB)( m-bib), where bib is the flexible N-donor bis((1 H-imidazol-1-yl)methyl)benzene linker (where o- and m- refer to ortho and meta positions, respectively) ligand and HTATB is the partial deprotonation mode from 4,4',4″- s-triazine-2,4,6-triyl-tribenzoic acid. Various Co-CPs have been directly applied in the field of supercapacitors. All these framework materials exhibit high capacitance, excellent energy delivery efficiency, and good cycling performance. For instance, the maximum specific capacitance for penetrated 3D networks is 2572 F g at 2.0 A g, and the mean energy delivery efficiency is up to 92.7% based on the tested current densities. Compared with extensional 2D layered and 3D networks, the 3D interpenetrated and polythreaded architectures could provide more active sites and thus promote fast charging and discharging processes. Furthermore, the Li uptake-release abilities of the Co-based CPs are also investigated, and the initial discharge capacity value for the 3D interpenetrated structures can reach up to 1792 mA h g at a current density of 50 mA g.