Mechanically and thermally robust microporous copolymer separators for lithium ion batteries

Next generation, multifunctional separators can enhance energy storage, power, and safety performance of lithium ion batteries but must be simple to fabricate incorporate with existing roll-to-roll manufacturing. This study presents a strategy facilely prepare these using UV-initiated polymerization-induced phase separation (PIPS), wherein microporous polymer are fabricated directly from constituent monomers ethylene carbonate (EC) porogen. enables wide compositional design space as co-monomers specific chemical functionality readily incorporated into the PIPS precursor mixture. Herein, 1,4-butanediol diacrylate (BDDA) was copolymerized poly(ethylene glycol) (PEGDA) increase acrylate conversion in photopolymerization improve mechanical properties. By tuning ratio PEGDA EC, high porosity (41.3%) effective ionic conductivity (2.09 mS cm−1) were prepared. Inclusion essential increasing elastic modulus > 345 MPa, which is required for cell assembly by All prepared shown enable reversible cycling metal/LiNi0.5Mn0.3Co0.2O2 half-cells 100 cycles. Unlike conventional polyolefin separators, melt at 160 °C shrink up 29.8% elevated temperatures, possess exceptional, safety-enhancing thermomechanical properties, undergoing no transitions or thermal shrinkage.