High-Energy Metallic Lithium Batteries Enabled by Polymer-in-Salt Electrolytes of Cyclic Carbonate Substituted Polyethers

Abstract

A class of polymer-in-salt electrolytes (PISEs) based on cross-linkable polyethers bearing pendant cyclic carbonate groups has been developed. This type of cyclic carbonate substituted polyether has a low glass transition temperature and shows good chemical and electrochemical stability. We have revealed the effects of the spacer length and the backbone on the ion conduction in detail. The PISE with a moderate interaction between polymer segments and lithium ions exhibits a higher ionic conductivity, and a nearly 3-fold increase in lithium ion transference number compared to that of conventional salt-in-polymer electrolytes. With a high concentration of salt, the growth of dendrites from the lithium–metal anode can be effectively suppressed and a uniform lithium deposition has been observed, which has been related to the formation of the inorganic-rich solid electrolyte interphase. Moreover, the in situ cross-linking of the PISE gives rise to a flexible yet mechanically robust elastomeric thin film with a fast lithium ion conduction, which eventually enables the good-performance all-solid-state Li/LiFePO4 batteries with high cycling stability and Coulombic efficiency at ambient conditions. This work is anticipated to advance the research of PISEs for potential applications in high-energy lithium metal batteries.

Mixed-Polarity Copolymers Based on Ethylene Oxide and Cyclic Carbonate: Insights into Li-Ion Solvation and Conductivity

“…43 In a different experimental study on polycarbonate-polyether copolymers with varying amounts of linear and cyclic carbonate linkages in the chain, it was found that Li + is preferentially solvated by the cyclic carbonates groups. 16,17 This phenomenon was observed at high salt concentrations, while at low salt concentrations, Li + primarily coordinated with EO units. Moreover, in POEM-r-PGCMA gel polymer electrolytes (swollen with 1:1 EC/DMC solvent), ions were found to be primarily solvated by the cyclic EC solvent, as is typical in polymer-free EC/DMC electrolytes.…”

“…Conversely, Morioka et al experimentally showed that in a linear PEO-polycarbonate, Li + was actually preferentially solvated by the carbonate groups, and the salt concentration-dependent conductivity and T g were characteristic of linear poly­(ethylene carbonate), not PEO . In a different experimental study on polycarbonate-polyether copolymers with varying amounts of linear and cyclic carbonate linkages in the chain, it was found that Li + is preferentially solvated by the cyclic carbonates groups. , This phenomenon was observed at high salt concentrations, while at low salt concentrations, Li + primarily coordinated with EO units. Moreover, in POEM- r -PGCMA gel polymer electrolytes (swollen with 1:1 EC/DMC solvent), ions were found to be primarily solvated by the cyclic EC solvent, as is typical in polymer-free EC/DMC electrolytes .…”

“…The POEM homopolymer has a dielectric constant of 10.3, 19 which is close to that of PEO (ε s ≈ 7), 20 while cyclic carbonate-substituted polyethers can exhibit much higher dielectric constants of around 62. 16,21 As we varied the content of the highly polar, glassy GCMA in the random copolymer (POEM-r-PGCMA), the difference in ionic conductivities is fully explained by T g effects without any additional contribution from polarity contrast. Raman and IR experiments further support these findings by revealing that Li + are exclusively solvated by the "low-polarity" OEM monomers.…”

“…To fully explore the potential of mixed polymer electrolytes, it is essential to understand how ionic species interact with functional groups of different polarities. In particular, we focus on polyether-poly­(cyclic carbonate) copolymers because the highly polar cyclic carbonate groups introduce significant polarity contrast to the material, and these polymers have been barely explored. − In this study, we synthesize and characterize random and block copolymers composed of oligo­(ethylene oxide) methyl ether methacrylate (OEM) and glycerol carbonate methacrylate (GCMA) monomers to investigate ionic interactions in copolymers exhibiting high polarity contrast. The POEM homopolymer has a dielectric constant of 10.3, which is close to that of PEO (ε s ≈ 7), while cyclic carbonate-substituted polyethers can exhibit much higher dielectric constants of around 62. , …”

Fabrication of Carboxylic Acid and Imidazolium Ionic Liquid Functionalized Porous Cellulosic Materials for the Efficient Conversion of Carbon Dioxide into Cyclic Carbonates

“…Carbon dioxide can be used as a starting material to produce various high value-added chemicals. One of the most useful and widely investigated reactions of carbon dioxide is its cycloaddition to epoxides for the synthesis of cyclic carbonates. , These can be used as polar solvent , and electrolyte of lithium batteries, , polycarbonate polyurethane precursors, pharmaceuticals, fine chemicals, and agricultural chemical intermediates . Therefore, many catalytic systems have been developed for the cycloaddition reaction of epoxides with carbon dioxide, such as metal complexes, frustrated Lewis pairs, super-bases, ILs, metal–organic frameworks (MOFs), and porous organic frameworks (POFs) .…”