Flexible High Density Energy Thin Film Capacitor Device Based on Oxide Films

Flexible high energy density capacitors were fabricated by depositing La-doped anti-ferroelectric PbZrO3 thin films using sol-gel spin-coating technique. Instead of normal platinized silicon wafer, ultra-thin metal foil was... [ view full abstract ]

Flexible high energy density capacitors were fabricated by depositing La-doped anti-ferroelectric PbZrO₃ thin films using sol-gel spin-coating technique. Instead of normal platinized silicon wafer, ultra-thin metal foil was adopted as flexible substrate. The use of buffer layer was necessary to prevent reaction and element diffusion between substrate and dielectric layer, and after literature survey and preliminary experiments, electrically conductive LaNiO₃ film was chosen and spin-coated onto SUS foil prior to the deposition of La-doped anti-ferroelectric PbZrO₃ thin films. It demonstrated the effectiveness as a barrier layer on the flexible austenitic metal foil substrate which ensured microstructure uniformity with clean interface between the substrate and the dielectric layer. Through this study, we were able to obtain the recoverable energy density of the value higher than 15 J/cm³, and the energy loss value less than 5 J/cm³ with the breakdown strength higher than 1 MV/cm. It was concluded that we were able to fabricate flexible anti-ferroelectric PLZO thin film capacitors coupled with ultra-thin austenitic steel foil substrates, which could be applied to various high energy density storage device applications. Among various PLZO films, 6 mol% La-doped PLZO thin film on the thin LNO buffer layer showed the best performance with uniform microstructure and ideal slim hysteresis loops, and high maximum and low remnant polarization values. Furthermore, these flexible thin film capacitors exhibited no performance degradation after 1000 bending cycles, proving their strong potential for flexible high energy density storage and conversion applications.