The Polymer Society of Korea

Abstract

We report a porous polymer separator (PHBA) for lithium metal batteries, fabricated via a simple one-step polymerization-induced phase separation (PIPS) process. As polymerization proceeds, the growing polymer network becomes less soluble in the solvent, inducing phase separation and forming interconnected pores. PHBA is constructed from three acrylate monomers: 1,6-hexanediol diacrylate (HDDA) for mechanical strength, butyl acrylate (BA) for mechanical flexibility, and acrylonitrile (AN) for electrolyte affinity. By adjusting the monomer composition, the pore structure, wettability, and electrochemical performance of PHBA can be effectively tuned. Structural, electrochemical, and interfacial analyses have confirmed enhanced electrolyte uptake and uniform Li⁺ transport, resulting in a high ionic conductivity of 1.41 mS cm⁻¹. Li/Li symmetric cells exhibit stable lithium plating and stripping for over 750 h with low overpotential. In Li/NCM811 full cells, PHBA retains 65.1% capacity after 200 cycles at 2C and 85.6% after 100 cycles at 60 °C (1C), outperforming a commercial polyethylene separator. These results demonstrate that simple PIPS processing combined with rational monomer selection enables practical, tunable porous separators for stable lithium metal batteries.