Ionic conductivity and mechanical properties of semi-interpenetrating networks based on poly(ethylene oxide)/polyvinyl alcohol/graphene oxide: a response surface methodology study

Development of solid polymer electrolyte (SPE) with rational ionic conductivity and mechanical stability for high-temperature solid-state lithium-ion batteries is still challenging. Herein, advanced semi-interpenetrating polymer networks (semi-IPNs) based on poly(ethylene oxide) (PEO)/polyvinyl alcohol (PVA)/graphene oxide (GO) nanoplatelets/lithium perchlorate salt (LiClO4) were prepared using solution-casting approach. The effects of PVA, LiClO4, and GO content variables on the ionic conductivity (IC), Young's modulus (YM), tensile strength (TS) and elongation-at-break (ELB) of the prepared solid polymer electrolytes (SPEs) were investigated using response surface methodology (RSM). Considering R2 values above 94%, it was found that tensile strength and elongation-at-break decreased by increasing LiClO4 and GO contents, respectively. The DSC results demonstrated that GO nanoplatelets could act as nucleating agents and improve crystallinity. SEM micrographs showed a change in surface morphology due to crosslinking of PVA, which was accompanied by loss of spherulites. In addition, morphological change of the samples and formation of aggregations due to incorporation of nanoparticles was detected. The remarkable ionic conductivity of 1.65 x 10-3 S/cm was obtained for the sample with 30% (by weight) of PVA, 0.6 phr GO, and 12 phr LiClO4. These observations indicated that the prepared solid polymer electrolyte nanocomposites could be used in solid Li-ion batteries with good ionic conductivity and mechanical stability.