With the growing demand for high energy and high power density rechargeable lithium-ion batteries, increasing research is focused on improving the output voltage of these batteries. Herein, a series of pyrrolidinium and piperidinium cations with various N-substituents (including cyanomethyl, benzyl, butyl, hexyl, and octyl groups) were synthesized and investigated with respect to their electrochemical stability under high voltages. The influence of substitutions at the N-position of pyrrolidinium and piperidinium cations on their high-voltage resistance was studied by both theoretical and experimental approaches. The voltage resistance was enhanced as the electron-donating ability of the substitutes increased. Furthermore, 1-hexyl-1methylpyrrolidinium bis(trifluoromethylsulfonyl) imide ([C 6 Py][TFSI]) exhibited the highest decomposition voltage at approximately 5.12 V and showed promising potential in a lithium-ion battery.

Lithium–sulfur (Li-S) batteries with exceptional theoretical capacities and environmentally friendly characteristics have been investigated as next-generation energy storage devices. However, the dissolution and diffusion of polysulfide result in a rapid capacity degeneration, which hinders their practical application. Here, poly­(ionic liquid) (PIL)-based core–shell structured nanofibers, poly­(pyrrole)@poly­(ionic liquid)–polyacrylonitrile (PPy@PIL–PAN), were prepared via electrospinning and followed by a surface polymerization of pyrrole. The as-prepared PPy@PIL–PAN nanofibers were implemented as a functional interlayer for Li-S batteries, and it is found that the cationic poly­(ionic liquid) framework could selectively adsorb polysulfide species in the electrolytes, contributing to effective shuttle inhibition as well as stable sulfur electrochemistry. Moreover, this work sheds light on an efficient approach to improving the performance of Li-S batteries by using PIL-based functional interlayers.

Carbon nanofibers (CNF) with a 1D porous structure offer promising support to encapsulate transition-metal oxides in energy storage/conversion relying on their high specific surface area and pore volume. Here, the preparation of NiO nanoparticle-dispersed electrospun N-doped porous CNF (NiO/PCNF) and as free-standing film electrode for high-performance electrochemical supercapacitors is reported. Polyacrylonitrile and nickel acetylacetone are selected as precursors of CNF and Ni sources, respectively. Dicyandiamide not only improves the specific surface area and pore volume, but also increases the N-doping level of PCNF. Benefiting from the synergistic effect between NiO nanoparticles (NPs) and PCNF, the prepared free-standing NiO/PCNF electrodes show a high specific capacitance of 850 F g at a current density of 1 A g in 6 m KOH aqueous solution, good rate capability, as well as excellent long-term cycling stability. Moreover, NiO NPs dispersed in PCNF and large specific surface area provide many electroactive sites, leading to high CO uptake, and high-efficiency CO electroreduction. The synthesis strategy in this study provides a new insight into the design and fabrication of promising multifunctional materials for high-performance supercapacitors and CO electroreduction.

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Understanding Li+ migration behavior in hybrid solid-state electrolytes (HSEs) is essential for realizing the conductivity of HSE and high energy density Li metal batteries. Here, a highly conductive HSE with...