Characteristics of Interpenetrated Polymer Network System made of Polyethylene Oxide-LiBF₄ Complex and Polystyrene as the Electrolyte for Lithium Secondary Battery

We propose a polymer blending method for preparing the PEO (polyethylene oxide)-LiBF₄ complex electrolyte for lithium secondary battery applying to the IPN (interpenetrated polymer network) gel electrolyte. The polymer blend mixture of PEO-PS (polystyrene)-LiBF₄ was prepared as a film by the hot-pressing method. The resulting IPN film was plasticized with the electrolyte solution of 0.5 M LiBF₄/EC(ethylene carbonate)-PC(propylene carbonate) (1 : 1 vol.), in which the formation of PEO-LiBF₄ complex was confirmed by the Raman spectroscopy. The basic properties as an electrolyte of Li metal batteries, i.e., ionic conductivity, chemical stability at the polymer gel electrolyte/lithium metal interface, and charge-discharge performance of the Li/(PEO-LiBF₄/PS) gel electrolyte/LiCoO₂ cell were studied and discussed.