A “Two‐in‐One” Strategy for Flexible Aqueous Batteries Operated at −80 °C

Abstract

The development of aqueous metal-ion batteries has attracted great attention due to their relatively low cost and high safety levels. However, their practical applications are hindered by the ease at which their aqueous electrolytes freeze. Inspired by the antifreezing properties of salts and alcohol cryoprotective agents, a "two-in-one" cryoprotective agent, hydroxyl-functionalized poly( ionicliquid) (PIL-OH)-based hydrogel electrolyte for aqueous lithiumion batteries (ALIBs) is developed. The synergy of both ionic hydration and hydrogen bond interactions between the PIL-OH and water molecules impairs the hydrogen-bond networks of water and depresses the freezing point of water below −80 °C. Benefiting from exceptional ultralow temperature tolerance, the prepared PIL-OH hydrogel exhibits a highly enhanced low temperature adaptability and a high ionic conductivity of 0.08 mS cm −1 at −80 °C. The PIL-OH hydrogel-based flexible ALIBs exhibit high flexible durability and good cycling stability with 93% capacity retention over 200 cycles at −80 °C. The PIL-OH hydrogel report herein opens up new opportunities for practical applications of wearable and flexible aqueous batteries at ultralow temperature environments, such as the North and South Poles.

Ionic Liquid-Type Additive for Lithium Metal Batteries Operated in LiPF6 Based-Electrolyte Containing 2500 ppm H2O

“…Lithium metal batteries (LMBs) have high energy densities and thus are considered as the most promising next-generation battery system to use in daily-life applications. − Ni-rich ternary electrodes, which have high gram capacity and operating voltages and are cost-effective and nontoxic, are used for the fabrication of LMBs with high energy densities. − However, Ni-rich cathodes have poor structural and compositional stability and are sensitive to HF and H 2 O in electrolytes. − Therefore, transition metal ions are leached, and unstable interfacial structures are formed in the cathode and anode, − thereby limiting the practical applicability of Ni-rich cathodes …”

Antibacterial and Angiogenic Poly(ionic liquid) Hydrogels

“…Since the first synthesis of quaternary ammonium salts by Jocobs et al in 1915, its antibacterial properties have been gradually discovered, which is also the first proposal of generalized poly (ionic liquids) (PILs) antibacterial agents [ 21 , 22 ]. The antibacterial mechanism is the positively charged ionic liquids (ILs) that attract the negatively charged bacterial cell walls through the anion–cation interactions [ 23 , 24 ]. Imidazolium PILs are one of the most widely used ILs, which have potent broad-spectrum bactericidal activity and slight cell toxicity [ 25 ].…”

Regulating Frozen Electrolyte Structure with Colloidal Dispersion for Low Temperature Aqueous Batteries

“…Although GOQDs can increase the temperature at which ice crystals appear during cooling, the DSC results during heating showed that the melting enthalpy decreased with the addition of GOQDs, indicating that the addition of GOQDs reduced the amount of ice crystallization. The water content and the non‐freezing water content could be calculated as follows: [21] $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr {{\rm W}}_{fs}\left({\rm \char37 }\right)={{{\rm \Delta }H}\over{{\Delta H}_{m,{\rm \ }{\rm H}2{\rm O}}^{^\circ{}}}}\times 100\hskip0.17em\char37 \hfill\cr}}$$$ $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr {{\rm W}}_{nfs}\left(\char37 \right)=1-{{\rm W}}_{fs}\hfill\cr}}$$$ …”