Celgard2320

Poly(ethylene glycol) (PEG, average M_n ≈400, 1k, 2k, and 6k g mol^–1), pyridine–2,6–dicarboxylic acid, thionyl chloride, m–phenylenediamine, 4,4–methylenedianiline, hexamethylene diisocyanate (HMDI), di–tert–butyl dicarbonate, triethylamine (TEA), 4–(dimethylamino)pyridine (DMAP), poly(acrylic acid) (PAA, average M_v ≈450,000 g mol^–1), N‐methyl‐2‐pyrrolidone (NMP), and dibutyltin dilaurate (DBTL) were purchased from Aldrich. Silicon nanopowder (Si, 99%, 30–50 nm) was purchased from NanoAmor. 1 m lithium hexafluorophosphate (LiPF₆) in a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) (1:1 vol%) with 10 wt.% of fluoroethylene carbonate (FEC) was purchased from Welcos Co., Ltd (Korea). Trilayer polypropylene/polyethylene/polypropylene (PP/PE/PP, Celgard2320, thickness: 25 µm) was used as a separator for electrochemical analyses. All other chemicals and solvents were purchased from reliable commercial sources and used as received.

Nylon 66 (M_w = 262.35) was purchased from Sigma-Aldrich (St. Louis, MA, USA). Formic acid (HCOOH) was provided by Katayama Chemical (Osaka, Japan) with a purity of 98–100%. Polyacrylonitrile (PAN, M_w = 150,000) was from Scientific Polymer Products, Inc (Ontario, NY, USA). Dimethyl sulfoxide (DMSO, M_w = 78.13) was supplied from PanReac AppliChem (Chicago, IL, USA) with a purity of 99.5%. All the other chemicals used were analytical grade. Liquid electrolyte, the EC solvent (battery grade, extra dry < 20 ppm of water), was purchased from Ferro Corp (Mayfield Heights, OH, USA) and used as received without further purification. The commercialized PP separator (Celgard 2320), provided by Celgard company (Charlotte, NC, USA) was regarded as the separator of Li-ion batteries for comparison.