Optimization of Laser‐Induced Graphene Electrodes for High Voltage and Highly Stable Microsupercapacitors

Abstract

Microsupercapacitors (µSCs) have received a lot of interest for their possible use in miniaturized electronics and in the field of the Internet of Things (IoT) to power distributed sensors. µSCs fill the gap between batteries and traditional capacitors, providing high power densities and acceptable energy densities to fulfill onboard power supply requirements, coupled with quick charge/discharge rates and extended lifetime. Charge balancing of µSCs is not a standard practice, although the optimization of electrodes can provide beneficial effects on the electrochemical performance and stability of the device. In this work, a charge‐balanced double‐layer µSC based on laser‐induced graphene (LIG) with [PYR14][TFSI] as an ionic liquid electrolyte is presented for the first time. The optimized device shows an improvement in terms of the increased lifetime of a factor of four and its energy efficiency is raised above 80%.

The Mass-Balancing between Positive and Negative Electrodes for Optimizing Energy Density of Supercapacitors

“…The charge-balanced μSC showed an improved performance: an increased lifetime of a factor of 4 and a raised energy efficiency of above 80%. 80 (10) Practice Monitoring of Two-Electrode Cell Devices. According to the charge balance, the above guidelines for the mass-balancing of SC devices have been proposed, but there still are some uncertain factors affecting the mass-balancing and, thus, electrochemical performance of SCs.…”

“…Their mass-balancing may involve the reasonable design of the configurations and in situ evaluation of the materials' performances. 74,80,119 Therefore, we must understand correctly and apply reasonably the basic principles and methods of mass-balancing to construct highperformance SCs. We believe that these analyses and guidelines are conducive to understanding and realizing mass-balancing to develop high-performance supercapacitors in the future.…”

“…As for the mass-balancing between positive and negative electrodes, the main challenges for large scale production of SCs are (1) preparing the low-cost electrode with both high mass-loading (commercial level) and high-performance like low mass-loading (laboratory level); ,, (2) realizing both high gravimetric and volumetric capacity of SC devices while maintaining well rate performance in high mass-loading (for most electrode designs, this needs a trade-off between the gravimetric and volumetric performances; (3) realizing the mass-balancing of the SC devices with especial configurations such as wearable, flexible, and microsupercapacitor devices. Their mass-balancing may involve the reasonable design of the configurations and in situ evaluation of the materials’ performances. ,, Therefore, we must understand correctly and apply reasonably the basic principles and methods of mass-balancing to construct high-performance SCs. We believe that these analyses and guidelines are conducive to understanding and realizing mass-balancing to develop high-performance supercapacitors in the future.…”

“…However, due to large ion sizes, high viscosity, and low ionic conductivity, the actual application of ionic liquid electrolytes is restricted . Similar to aqueous and organic electrolytes, the mass matching of ionic liquid-based SCs still follows the charge balance principle. ,,, But in view of these features of ionic liquid electrolytes, we should fully consider the wettability of ionic liquids to electrode materials as well as their ion transport kinetics in realizing the mass-balancing of ionic liquid-based SCs.…”

“…For microsupercapacitors (μSCs) with interdigitated laser-induced graphene electrodes and [PYR14]­[TFSI] ionic liquid electrolyte, Zaccagnini et al developed a new charge-balancing (mass-balancing) method for the first time: a three-electrode setup was designed and constructed to evaluate the single electrode properties, which were used to determine an optimal areal ratio (A + /A – ) of positive to negative electrodes for a μSC device. The charge-balanced μSC showed an improved performance: an increased lifetime of a factor of 4 and a raised energy efficiency of above 80% …”