Graphene-PVDF composite membrane for piezoelectric nanogenerators and lithium-ion batteries

Abstract

Herein, we introduce a composite membrane comprising polyvinylidene fluoride/graphene nanosheets (PVDF/graphene) for applications in piezoelectric nanogenerators (PENGs) and lithium-ion batteries (LIBs), where the graphene nanosheets play a vital role in enhancing the piezoelectric properties, surface energy, and porosity. A comparative analysis of the pure PVDF and the PVDF/graphene is conducted to evaluate their piezoelectric performance and suitability as separators in LIBs. The PVDF/graphene composite membrane produced a significantly improved piezoelectric output of ∼10.8 V under a force of 75 N, while the pure PVDF membrane exhibited only ∼3.7 V under the same conditions. Additionally, the Li//PVDF/graphene//graphite half-cell retained ∼81.3% of its specific capacity and maintained a coulombic efficiency of over 99.2% after 100 cycles at a 0.2 C rate. In contrast, the Li//pure PVDF//graphite half-cell retained only ∼48.6% specific capacity. Furthermore, in a full-cell configuration, the graphite//PVDF/graphene//LCO cell demonstrated excellent stability, retaining ∼88% of its specific capacity after 50 cycles, whereas the cell with pure PVDF membrane retained only 38%. Therefore, the PVDF/graphene nanosheet composite membrane has the potential to be used as a piezoelectric membrane in PENGs and as a separator in LIBs.