Photo‐Cross‐Linked Single‐Ion Conducting Polymer Electrolyte for Lithium‐Metal Batteries

Abstract

Polymer electrolytes are considered potential key enablers for lithium-metal batteries due to their compatibility with the lithium-metal negative electrode. Herein, cross-linked self-standing single-ion conducting polymer electrolytes are obtained via a facile UV-initiated radical polymerization using pentaerythritol tetraacrylate as the cross-linker and lithium (3-methacryloyloxypropylsulfonyl)-(trifluoromethylsulfonyl)imide as the ionic functional group. Incorporating propylene carbonate as charge-transport supporting additive allowed for achieving single-ion conductivities of 0.21 mS cm −1 at 20 °C and 0.40 mS cm −1 at 40 °C, while maintaining a suitable electrochemical stability window for 4 V-class positive electrodes (cathodes). As a result, this single-ion polymer electrolyte featured good cycling stability and rate capability in Li||LiFePO 4 and Li||LiNi 0.6 Mn 0.2 Co 0.2 O 2 cells. These results render this polymer electrolyte as potential alternative to liquid electrolytes for high-energy lithium-metal batteries.

Polysiloxane‐Based Single‐Ion Conducting Polymer Blend Electrolyte Comprising Small‐Molecule Organic Carbonates for High‐Energy and High‐Power Lithium‐Metal Batteries

“…[40] The structural features of the anionic trifluoromethanesulfonylimide group are evident at v̅ = 1326 and 1114 cm −1 for the S  O bond and at 1187 cm −1 for the C-F bond. [41,42] Following this confirmation of the complete reaction of the two educts, the PSiO ionomer was blended with PVdF-HFP to yield selfstanding polymer electrolyte membranes (PSiOM; Figure 1c) with a thickness of about 45 ± 5 µm (Figure S2, Supporting Information) and high thermal stability exceeding 240 °C (Figure S3, Supporting Information).…”

“…Synthesis of the PSiO Ionomer and Preparation of the PSiOM Electrolyte Membranes: Lithium (3-methacryloyloxypropylsulfonyl) (trifluoromethylsulfonyl)imide (LiMTFSI) was synthesized according to a previous study. [42] Subsequently, LiMTFSI (3.36 g, 9.75 mmol), 1.31 g poly[(mercaptopropyl)methylsiloxane] (PMMS, SMS-992, M w = 4000−7000, 75−150 cSt, Gelest), and 66 mg 2,2-azobis(2methylpropionitrile) (AIBN, purified through recrystallization before use) were dissolved in 20 mL anhydrous tetrahydrofuran (THF) in a Schlenk flask. The above mixture was stirred under argon at 65 °C for 12 h to complete the polymerization (Scheme S1, Supporting Information).…”

Solid-State, Single-Ion Conducting, Polymer Blend Electrolytes with Enhanced Li+ Conduction, Electrochemical Stability, and Limiting Current Density

“…The limiting current density of PLiMTFSI–52/POEM, r = 10:1, was 1.8 mA/cm 2 , i.e., the highest current density at which a steady-state potential was reached. The limiting current density of the SIC polymer blend electrolyte (1.8 mA/cm 2 , electrolyte thickness, L , = 0.05 cm) was comparable to the theoretical limiting current density of PEO/LiTFSI (∼1.8 mA/cm 2 , electrolyte thickness = 0.025 cm) at the same ion concentration and surpassed that of a number of solvent-plasticized SIC polymers. − Although the effect of the electrolyte thickness on the limiting current density has been well established for dual-ion-conducting polymers, such a study is not commonly undertaken for SIC systems. ,, Theoretically, limiting current densities in SIC polymers should be close to infinity as t Li+ approaches 1 if one can neglect chain mobility (and thereby no anion mobility). ,, Herein, in comparison to solvent-plasticized SIC systems, the enhanced limiting current density could be attributed to the high- M n PLiMTFSI with bulky side groups and transient TFSI – –Li + –EO crosslinks at high ion concentrations ( r = 10:1). − Both features significantly reduce the ion mobility in this solid-state, SIC, polymer blend electrolyte.…”

Pendent Sulfonylimide Ionic Liquid Monomers and Ionoelastomers via SuFEx Click Chemistry

“…All EA- x ionoelastomers had >90% transmittance for essentially the entire visible spectrum (Figure C). Alternatively, pendent sulfonylimide polymers with monomers synthesized using the conventional method often have a hazy yellow-brown color, despite their nonpolymerizable counterparts being clear slightly yellow liquids or white salts. ,,− …”