Polarization of ionic liquid and polymer and its implications for polymerized ionic liquids: An overview towards a new theory and simulation

Abstract

Ionic liquid (IL)‐containing polymers garner attention for electrochemical applications. This article overviews recent experimental and theoretical studies of polymer electrolytes that would be likely to cultivate new theoretical and computational frameworks for IL‐containing polymers. The first two sections outline the uniqueness of ILs that differentiates them from inorganic salts in polymers and explore deviation from the concept of the metaphor “room‐temperature molten salt.” Such distinct properties include (1) large intrinsic dipole moment and electronic polarizability, (2) hydrogen bonding, (3) π‐interactions, (4) a broad distribution of charges over the entire ion, and (5) the anisotropy of the ions. Moreover, the complexity of these properties substantially increases when the ions are polymerized. Indeed, their exceptional features would overcome the hurdle due to a trade‐off between ionic conductivity and mechanical robustness in inorganic salt‐doped polymers. Given these facts, the rest of the article focuses on emerging trends in the study of the dielectric response, phase separation, ion conductivity, and mechanical robustness of the polymer electrolytes, highlighting outstanding observations in experiments that may inspire existing theory and simulation. Our discussion also includes improving computational complexity for IL‐containing polymers. To this end, recent machine learning studies that consider ILs and polymer liquids are presented.

Flexible Sustained Ionogels with Ionic Hyperbranched Polymers for Enhanced Ion-Conduction and Energy Storage

“…The improvement in ionic conductivity can be attributed to the screening of interfacial interactions of nanocellulose framework by absorbed PILs that facilitate ion liquid transport through open continuous pores with minimum dissipation of energy. 45,46 3.4. Energy Storage Performance Demonstration.…”

“…The known electrolyte materials are categorized based on their solvent by aqueous, organic, and ionic liquid-based and emphasis was given to supercapacitors that used carbonbased electrodes (rGO and other carbon materials) for comparison reasons and to avoid any pseudocapacitive contributions. 13,45,54,55 Comparison was conducted to other ionic liquid-based electrolytes reported to date, such as poly(vinyl alcohol) (PVA)/cross-linked poly(2-hydroxyethyl methacrylate) (C-pHEMA)/60 wt % EMIMBF 4, 50 poly-(vinylidene fluoride) (PVDF)/ZIF-8/74 wt % EMITFSI, 56 polyoxyethylene/nitrile butadiene rubber (PEO/NBR) with 70 wt % EMIBF 4, 59 epoxy/Al 2 O 3 /50 wt % BMIM-TFSI/ LiTFSI, 13 and PVA/35 wt % BMIMCl-Li 2 SO 4 (Figure 7b). 50 The CNF-based ionogels demonstrated comparable specific energy values (36.9−37.5 Wh/kg) resulting from the high ionic liquid content (88−90 wt %) and the porous CNF networks that accommodate ion-transport (Figure 7b).…”

“…Increasing the hyperbranched polymer ionic group density, ionic conductivity increased up to 6.2 ± 0.3 mS/cm (for CNF/CNC/PIL-64 (IL)). The improvement in ionic conductivity can be attributed to the screening of interfacial interactions of nanocellulose framework by absorbed PILs that facilitate ion liquid transport through open continuous pores with minimum dissipation of energy. , …”

“…In addition, we conducted comparative analysis of the specific energy (Wh/kg) of supercapacitors containing different solid or gel electrolytes (Figure b and Table S9). The known electrolyte materials are categorized based on their solvent by aqueous, organic, and ionic liquid-based and emphasis was given to supercapacitors that used carbon-based electrodes (rGO and other carbon materials) for comparison reasons and to avoid any pseudocapacitive contributions. ,,, Comparison was conducted to other ionic liquid-based electrolytes reported to date, such as poly­(vinyl alcohol) (PVA)/cross-linked poly­(2-hydroxyethyl methacrylate) (C-pHEMA)/60 wt % EMIMBF 4, poly­(vinylidene fluoride) (PVDF)/ZIF-8/74 wt % EMITFSI, polyoxyethylene/nitrile butadiene rubber (PEO/NBR) with 70 wt % EMIBF 4, epoxy/Al 2 O 3 /50 wt % BMIM-TFSI/LiTFSI, and PVA/35 wt % BMIMCl-Li 2 SO 4 (Figure b) …”

Zwitterionicversusorganic ionic plastic crystal electrolytes with mixed anions: probing the unique physicochemical and electrolyte properties

“…For example, it has been shown that in both ionic liquid and polymer electrolytes, the ionic interactions between Li + and other ions or ionic functional groups can have an important impact on ion transport, aggregation and even the formation of conducting nanochannels. 39,49 In the zwitterion electrolytes, the tethered cationic and anionic species could change the polarizability, aggregation and ion transport characteristics compared to the OIPC systems. Future work, including simulation studies, will be used to further understand these differences.…”