Fabrication And Properties Of Flexible Integrated Self-charging Batteries Based On Piezoelectric Nanofiber Membrane

Self-charging batteries draw on nanogenerators and lithium-ion batteries,integrate energy conversion and energy storage technologies into a single device unit.It improves the energy conversion efficiency by converting the mechanical energy in the environment into electrical energy and storing it,which is expected to alleviate the current severe energy crisis.Self-charging batteries have expanded the research on micro-nano energy sources,but have the defects of low energy conversion efficiency and poor cycle stability.The reasons lie in the following aspects: First,the output performance of the piezoelectric diaphragm is weak,and the mechanical energy cannot be fully converted into piezoelectric energy,which reduces the energy utilization rate.Second,the traditional battery structure is not suitable for self-charging batteries.The rigid battery casing absorbs most of the mechanical energy,reducing the amount of energy transferred to the piezoelectric diaphragm.In view of the above problems,this paper designed a flexible self-charging battery which based on piezoelectric nanofiber membrane and water-based electrode.On this basis,the effects of material ratio,preparation process and test environment on the selfcharging performance of SCPC were systematically studied,which effectively improved the storage capacity of SCPC and provided a theoretical basis for the practical application of SCPC.The specific work content is as follows:（1）The prepared high-performance piezoelectric nanofiber membrane enables the output performance of self-charging batteries to be improved.The PVDF-Tr FE/PEG/TPU（P-P-T）piezoelectric nanofiber membranes were rapidly and efficiently prepared based on electrospinning process,and PEG was etched by ethanol.The method promoted the crystallization of PVDF-Tr FE and generate a large number of β-phases by high-voltage electric field stretching and the hydrophilicity of PEG,prepare a unique hierarchical micronano pore structure,improve the porosity,specific surface area of the nanofiber membrane,and the output performance.（2）The use of integrated battery structures to improve the electrochemical and cycling performance of self-charging batteries.Because of the hydrophobicity of PVDF-Tr FE.An integrated battery structure of positive electrode/P-P-T film/negative electrode is prepared by directly scraping the water-based electrode slurry onto the surface of the film,which realizes the close combination of the electrode and the separator,enhances the traction of lithium ions by the electric field force,and improves the self-charging capability performance of the SCPC.（3）Assembled flexible devices to improve the energy utilization and conversion efficiency of self-charging batteries.The preparation of flexible self-charging batteries uses flexible films such as polyimide as outer packaging,which avoids excessive loss of mechanical energy on rigid packaging and improves energy utilization.The SCPC can achieve high storage capacity（0.092 μA h）under the action of small periodic compressive stress（1 Hz,6 N）,which improves energy utilization and conversion efficiency.In addition,the SCPC was also tested for environmental suitability.It is found that it has good application ability,provides great potential for flexible self-powered devices,and has broad application prospects in the fields of wearable electronic devices and implantable medical devices.