In this research, the advantages of using biodegradable polylactic acid (PLA) substrate for printed supercapacitor (SC) are investigated by studying the supercapacitor’s cyclic bending reliability, failure mechanism, and the impact of the bending radius. The research has gained three interesting and significant findings: (1) Failure mechanism: the supercapacitor, except the ones with PLA/Al substrate, failed to the flaking-off of the carbon particles from the electrode, which migrate to the porous areas of the fiber structure of the separator, establishing the short circuits and leading to the increase of leakage current. The fiber structure of the separator paper, which is usually considered easy to break, was actually not broken. (2) Failure location: the failures commonly occurred to the short edges and corners of the electrode, rather than the middle area of it. This is due to the strain concentration in those areas caused by the small radius of the area during the repeated bending. (3) PLA: the results firmly proved that using PLA/barrier laminate as substrate for flexible supercapacitor is advantageous than the aluminum foil in preventing the evaporation of liquid electrolyte, bending radius stability, and bending reliability. The research suggests that using PLA/barrier substrate, developing more robust activated carbon electrodes, developing cellulose paper with more dense fiber structure and smaller porous areas, and controlling the bending radius are crucial to improving the SC’s reliability.
Zhao Fu et al. recently published an article about printed biodegradable flexible supercapacitor on the journal ACS Applied Materials & Interfaces