Ionic Conductivity Enhancement of Polymer Electrolytes by Directed Crystallization

Abstract

We report that hot stretching of poly­(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) can lead to a preferred orientation of PEO crystalline lamellae, thereby reducing the tortuosity of the ion-conduction pathway along the thickness direction of the SPE film, causing improved ionic conductivity. The hot stretching method is implemented by stretching SPE films above the melting point of PEO in an inert environment followed by crystallization at room temperature while maintaining the applied strain. The effect of hot stretching on the crystalline orientation, crystallinity, morphology, and ion transport in PEO with two types of salts, lithium bis­(trifluoromethanesulfonyl)­imide (LiTFSI) and lithium triflate (LiCF3SO3), is investigated in detail. Wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS) show that the orientation of PEO crystalline lamellae induces the formation of a short ion-conduction pathway along the through-plane direction of the SPE films, leading to 1.4- to 3.5-fold enhancement in the through-plane ionic conductivity.

Modification of Nias’ Cacao Pod Husk Cellulose through Carboxymethylation Stages by Using MAOS Method and Its Application as Li‐ion Batteries’ Biopolymer Electrolyte Membrane**

“…In this work, complexed-membrane of MC/CMC (80/20) + 10 % LiClO 4 has lower crystallinity index than blend membrane of MC/CMC (80/20) cause complexed-membrane of MC/CMC (80/20) + 10 % LiClO 4 has higher ionic conductivity than blend membrane of MC/CMC (80/20). It agrees with some previous research such as, [71,72] where the amorphous phase increases ionic conductivity as lithium salt consequence which disrupts the crystallinity. [73] Thermal analysis of biopolymer electrolyte membrane Thermal stability is important in battery cell to prevent overheating, which is probably caused by overcharging.…”

The Unexpected Role of Cations in the Self-Assembly of Positively Charged Amphiphiles at Liquid/Liquid Interfaces

“…This result shows that Li + directly interacts with the tail, pinning it to the interface, in a manner that is analogous to previously reported H-bonding interactions at air/aqueous interfaces decorated with ODMS-MIM + . The binding of Li + to the tail parallels the interactions found in solutions, , polymers, battery materials, − and small molecules , where solvation and pairing interactions of the Li + cation by oxygen moieties were found. Similarly, recent work has shown how contact ion pairs are preferable in Li + binding to sulfate headgroups, yet they possess weak thermodynamic binding affinities relative to larger cations .…”

Solid-State Electrolytes for Lithium–Sulfur Batteries: Challenges, Progress, and Strategies

“…Liu et al reported a hot drawing technique by which crystalline sheets perpendicular to the drawing direction were selected, and the crystallinity of the electrolyte was reduced. As shown in Figure 3 a, this enhanced ionic conductivity in the through-plane direction of the SPE films by reducing the ionic conduction pathway [ 49 ]. Liang et al combined the zirconia skeleton (ZrO 2 @ILs) with the vertical channel of fast Li ion movement generated by hydrolysis in situ with PEO to enhance the conductivity and mechanical properties of electrolyte ions, as shown in Figure 3 b.…”

“… ( a ) Schematic diagram of different electrolyte lamellar orientations and lithium-ion transport pathways (Reprinted with permission from [ 49 ]; Copyright 2022, ACS Macro Letters); ( b ) PEO polymer with ZrO 2 @ILs vertical channel design to improve mechanical strength and ionic conductivity (Reprinted with permission from [ 50 ]; Copyright 2021, ACS Applied Materials & Interfaces). ( c ) Schematic diagram of polysulfide and lithium-ion transport by graphene-coated PP diaphragm (Reprinted with permission from [ 53 ]; Copyright 2018, ACS Applied Materials & Interfaces).…”