High-Performance Supercapacitors with Femtosecond-Laser-Nanostructured Current Collectors

The interfacial resistance between a current collector and an active material of a supercapacitor leads to energy losses and a decrease in the specific power of the device. In addition, low adhesion of the active material to the collector can cause degradation of the supercapacitor during operation. In this study, we propose a method to reduce the interfacial resistance at the interface between a current collector and active material by forming laser-induced periodic surface structures (LIPSS). We show that laser structuring in inert gas (N₂) environment results in improvement of electrochemical characteristics of supercapacitors. The charge-transfer resistance determined by the voltage drop during the cell discharge after femtosecond laser processing of the collectors decreases by 90% compared to the untreated collectors. The main effects of improving the electrochemical characteristics can be understood by an increase in the contact area between the electrode material and the collector due to the formation of LIPSS, which reduces the specific resistance. Laser structuring also causes certain chemical changes on the surface of the current collector, which can contribute to improving the electrical conductivity and the chemical stability of the contact. The LIPSS on the surface improves the adhesion of the active material to the current collector, which reduces the risk of mechanical delamination during the cyclic charge-discharge processes. A significant reduction in internal resistance with nanostructured electrodes opens promising avenues for increasing the specific power of supercapacitors of various types. The laser processing method does not require the use of additional reagents or multicomponent sublayers, which simplifies the approach and makes it attractive for application requiring scale up.