Fabrication of pectin biopolymer-based biocompatible freestanding electrodes for supercapacitor applications

Implantable energy storage devices that are soft, flexible, biocompatible, and biodegradable are the focus of current bio-instrumentation research. Polymer gel-based electrodes for energy storage applications such as supercapacitors and rechargeable batteries have a wide attraction for modern technology. This work proposes a flexible, transparent, and biodegradable electrode using pectin biopolymer with a biocompatible electrolyte as a supercapacitor. The biopolymer pectin can be a promising candidate for such energy storage devices. Polyethylene glycol (PEG) was added with pectin, which forms side chains for better stability and conductivity, improving the electrode materials' ionic conduction. Two devices were fabricated using pectin only (PO) and pectin/PEG (PP) composite as electrode materials. The interesting observation with PO was that it has slightly higher specific capacitance (C-SP) than PP composite, but the long-time retention was poor. Graphite was incorporated in the Pectin/PEG composite and fabricated two more devices with Pectin/PEG/Graphite (PPG) composite-based biosupercapacitors using a 10% and 20% weight ratio of graphite to pectin. An electrochemical study was performed to understand the energy storage capacity of the fabricated electrodes. It was found that the 10% graphite incorporated sample showed excellent retention of 98.74% of capacitance with a specific capacitance of 11.48 mF/cm(2) over 2500 cycles. With the increased stability and higher specific capacitance, pectin biopolymer-based electrodes have a powerful impact on developing flexible and portable solid-stat energy storage e systems.