Photovoltaically self-charging cells with WO3·H2O/CNTs/PVDF composite†
Two-electrode photovoltaically self-charging cells (PSCs) possess compact structures for both energy conversion and storage with shared electrolyte and electrodes. It remains challenging to develop PSCs that are efficient in both energy conversion and storage. In this work, WO3·H2O nanoplates were synthesized by a modified acid-directed hydrothermal process and used to prepare a WO3·H2O/CNTs/PVDF composite film for energy storage in PSCs. The method with the assistance of polyethylenimine was essential to form smaller sized WO3·H2O nanoplates, thus larger surface area and higher columbic efficiency in cyclic voltammetry tests. Such an electrode composite made it more facile to assemble PSCs, which displayed an energy conversion efficiency of 2.12% with simultaneous energy storage of 1.38 C cm−2. Higher Li+ concentration in the electrolyte will be helpful to maintain the photocurrent at a larger value during irradiation. A higher performance of PSCs can be potentially obtained by optimizing the contact of electron collector and pseudocapacitive electrode materials.