Monolithic Task‐Specific Ionogel Electrolyte Membrane Enables High‐Performance Solid‐State Lithium‐Metal Batteries in Wide Temperature Range

Abstract

Monolithic ionogel electrolyte membranes (IGEMs) based on gelling scaffolds and ionic liquids have aroused intensive interest because of their broad processing compatibility, nonflammability, and favorable thermal and electrochemical features. However, the absence of functional scaffolds that concurrently enable high mechanical strength and Li+ transportability of IGEMs constrains the battery power and safety. Herein, a task‐specific IGEM monolith featuring high Li+ conductivity and outstanding thermal stability is demonstrated, whereby electrospun positively charged poly(ionic liquid) nanofibers serve as a thermotolerant scaffold for the IGEM. Regulating the Li+ environment in the IGEM enables the shift from the sluggish vehicular to fast structural Li‐ion transport mode. With the unique IGEM, the solid‐state Li||LiFePO4 cells achieve improved rate capability and good cyclability in a wide temperature range from 0 to 90 °C. Furthermore, practical solid‐state Li||LiFePO4 pouch cells with a cathode capacity of ≈2 mAh cm−2 have also been demonstrated.

Enabling High‐Voltage “Superconcentrated Ionogel‐in‐Ceramic” Hybrid Electrolyte with Ultrahigh Ionic Conductivity and Single Li+‐Ion Transference Number

“…The conductivity-temperature curves have been generally reported to show break slopes, which could be attributed either to the dissociation of ion pairs or to the disappearance of wall-to-ions interactions. [29,46] However, the conductivity of present SIC electrolyte is comparable with or even higher than those of the studied ionogels, [30] for example, the electrospun polymerized ionic-liquid poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide/poly(2,2,2-trifluoroethyl methacrylate) ionogel presented conductivity ≈5 × 10 −5 S cm −1 at −20 °C; [47] the hybrid silica/PVDF-co-hydroxyethyl acrylate ionogel showed conductivity below 10 −5 S cm −1 at −20 °C; [25] the TiO 2 ionogel exhibited conductivity ≈10 −4 S cm −1 at −10 °C; [48] Adv. Mater.…”

Novel poly(epichlorohydrin)-based matrix for monolithic ionogel electrolyte membrane with high lithium storage performances

“…The ionic conductivity depends largely on temperature and increases signicantly as the temperature increases from 20 to 70 C. The MIEMs exhibit high ionic conductivities of 1.21 and 4.49 mS cm À1 at 20 and 70 C, respectively, higher than those of the counterparts as reported in literatures. 5,[42][43][44][45][46][47] This trend could be ascribed to the increase in the exibility of the MIEM and faster diffusion of the ions with increasing temperatures. The ionic conductivity of LIBs should exceed 0.1 mS cm À1 in the working temperature ranges of 20-70 C, and the MIEM prepared herein fullled this requirement.…”

Toward Understanding the Effect of Fluoride Ions on the Solvation Structure in Lithium Metal Batteries: Insights from First-Principles Simulations

“…However, TFSI − has large steric hindrance and molecular weight, which makes Li ions migrate by a slow vehicular transport mechanism. 53 In the fluorinated electrolyte, the large electronegativity of F − drives it to replace TFSI − and coordinate with Li + , forming an FLS structure (Figure 1a). The FLS structure transformed the Li + transport mechanism from the sluggish vehicular transport to a fast structural ion transport mode, which enhanced the Li + transport kinetics.…”

“…The constant distance between Li and N means that Li + migration was associated with TFSI – during the Li + diffusion. However, TFSI – has large steric hindrance and molecular weight, which makes Li ions migrate by a slow vehicular transport mechanism . In the fluorinated electrolyte, the large electronegativity of F – drives it to replace TFSI – and coordinate with Li + , forming an FLS structure (Figure a).…”