Cyclic Bending Reliability and Failure Mechanisms of Printed Flexible Supercapacitors

Printed flexible supercapacitor (SC) is an advantageous energy storage device for sensor powering, whereas its mechanical reliability remains to be a challenge, which is related to the electrode and separator. Herein, we study the impacts of electrode material, the material and fabrication of separator, thickness and bending radius of on the reliability and failure mechanisms of flexible SC using cyclic bending test. The electrical measurement, imaging, and chemical analysis were used to identify and analyze the failures. It was found that cellulose paper separator, PANI/carbon electrode, and low thickness together contributed to the higher reliability of flexible SC. In comparison, the bending radius has a minor impact. Two failures mechanisms were common and dominant: (1) breakage of current collector; (2) the activated carbon particles lost from electrode and entered the largely cracked areas of printed separator, forming conduction paths, and leading to the increase in leakage current.