Ion Dynamics of Water‐in‐Salt Electrolyte with Organic Solvents in Nanoporous Supercapacitor Electrodes

Abstract

Water-in-salt electrolytes blended with organics solvents, that is, organic solvent/water mixed electrolytes, are promising for applications in next-generation energy storage devices vitally needed for industrial electrification and decarbonization. However, the electrolyte ion diffusion behaviors within nanoporous supercapacitor electrodes are poorly understood. Here a systematic investigation into supercapacitor resistances and ion kinetics is carried out experimentally and with numerical simulations. The electrochemical results on the nanoporous electrodes reveal a nonmonotonic (decreasing, increasing, and then decreasing) trend of supercapacitor resistances with increasing solvent mobility, challenging the long-held views that supercapacitor resistances decrease with elevated mobility of organic solvent. The abnormal trend is examined by numerical molecular dynamics simulations of electrolyte ion diffusion within 0.95 nm nanochannels. The electrolyte conductivity is related to cation-anion interactions within nanochannels. We further confirm the crucial interplay of the van der Waals sizes of solvent molecules and channel width in determining electrolyte conductivity in nanoporous electrodes.

Construction of Bio‐inspired Film with Engineered Hydrophobicity to Boost Interfacial Reaction Kinetics of Aqueous Zinc–Ion Batteries

“…Based on the statistical theory, we uniformly selected the number of water molecules in the range of 4 Å as the average coordination number (ACN) in the solvated shell of Zn 2+ . [ 60,61 ] As shown in Figure 6c, a strong peak from the RDF of Zn‐H 2 O is centered at ≈2.2 Å, a large amount of H 2 O is present in the Zn 2+ solvation sheath. [ 25 ] After statistical analysis, the ACN of hydrated Zn 2+ is calculated to be around 4.8 from 0 to 1500 steps (Figure 6c, above).…”

Experimental Investigations on Highly Conducting Solid Bio‐Polymer Electrolytes Based on Latex of Calotropis gigantea Plant

“…[28] Li et al, developed a supercapacitor using water in salt electrolyte, with organic solvent (ACN, GBL, PC) electrolyte and nano-porous activated carbon electrode. [29] In recent times, an important field of research has come up in the formation of polymer latex film. A proportion of latex is being cast into films which act as ionic source or binder.…”

Fluorinated Ether‐Based Electrolyte for Supercapacitors with Increased Working Voltage and Suppressed Self‐discharge

“…Tailoring electrolytes to suppress self-discharge of supercapacitors has received increasing attention in recent years. [35][36][37][38][39] For example, Zhang et al examined lithium hexafluorophosphate in ethylene carbonate-diethyl carbonate (LiPF 6 /EC-DEC) and TEABF 4 in propylene carbonate (PC) as electrolytes for supercapacitors and discovered different control mechanisms for the self-discharge processes. [40] Recently, using electrolyte additives such as liquid crystals has proved to be effective in suppressing the self-discharge of supercapacitors.…”

“…On another hand, electrolytes also play an important part in regulating the self‐discharge of supercapacitors through governing the transport of ions and reactive species at the electrode/electrolyte interface. Tailoring electrolytes to suppress self‐discharge of supercapacitors has received increasing attention in recent years [35–39] . For example, Zhang et al.…”