Phosphor copper-based flexible high voltage supercapacitors fabricated via laser irradiation and three-dimensional packaging

Abstract

Supercapacitors (SCs) have garnered increasing attention as an alternative energy storage device but the relatively low potential window and energy density impede their application prospect. Herein, we propose a novel three-dimensional (3D) packaging method for the first time, utilizing high flexible phosphor-copper sheets (PCSs) sprayed with polytetrafluoroethylene (PTFE) and covered with polyimide (PI) films on their both sides as the serial medium followed by CO 2 laser irradiation to fabricate all-solid-state flexible high voltage supercapacitors (HVSCs). This method achieves double voltage output in the limited PI membrane compared with common 2D encapsulation. As a result, as-obtained HVSCs deliver not only an enhanced mechanical tensile strength up to 18.23 MPa but also the outstanding electrochemical performances, including ultrahigh working voltage window (10 V), high energy density (37.68 μWh/cm 2 ) and power density (3.38 mW/cm 2 ). Owing to the excellent flexibility, the HVSCs can be arbitrarily bent or twisted without obvious attenuation on capacitive property. After 10000 cycles, the capacitance retention of HVSCs still maintains to be 90.2%. This novel 3D packaging strategy may pave the way for developing high-performing SCs with wide operating voltage and high energy density for flexible displays, wearable equipment and integrated electrical devices. • PI films were pasted on the upper and lower surfaces of phosphor copper sheet. • Graphene formation from laser irradiation on PI film surface. • Phosphor copper-based supercapacitor was prepared by a novel 3D packaging method. • HVSCs deliver enhanced tensile strength, high working voltage and energy density.