Flexible MXene/Laser‐Induced Porous Graphene Asymmetric Supercapacitors: Enhanced Energy Density of Lateral and Sandwich Architectures Under Different Electrolytes
Sanju Gupta, Magdalena Narajczyk, Mirosław Sawczak, Jacek B. Jasiński, Robert Bogdanowicz, Shubin Yang
Abstract
Abstract Deployment of 2D layered materials beyond graphene, i.e., MXene (Ti 3 C 2 T x , T = ─OH, F, O) is rigorously explored for generation‐II electrochemical energy storage systems. The strategic development of asymmetric supercapacitors (ASCs) comprising MXene as negative and laser−induced porous graphene (LIPG) as a positive electrode (i.e., MXene//LIPG) is reported to improve electrochemical energy storage in lateral (coplanar) and sandwich (cofacial) device configurations. Moreover, the interdigitated lateral device is scalable, flexible, current−collector, and binder‐free. Electrochemical performance is evaluated under various electrolyte compositions: aqueous (AE), organic (OE), and ionic liquid (ILE). Notably, ASCs operate up to ≈1.0 V with AE, 1.6−2.0 V with OE, and 2.4−3.0 V with ILE exhibit enhanced energy densities depending upon the electrolyte and 100% Coulombic efficiency while retaining 75–95 % of initial capacitance after thousands of cycles (≥10 000–200 000). Specifically, the highest specific energy density (289 mW h cm −3 at power density 0.2 W cm −3 ) is recorded for ILE‐sandwich, seven times higher as compared with AE‐sandwich (40 mW h cm −3 at power density 0.4 W cm −3 ) followed by intermediate value for OE‐lateral (8.5 mW h cm −3 at power density 0.14 W cm −3 ) device. On the other hand, symmetric (MXene//MXene) device provided for sandwich (ILE: 12 W h cm −3 at power density 0.5 W cm −3 ; OE: 8.8 mW h cm −3 at power density 0.1 W cm −3 , AE: 4.2 mW h cm −3 at power density 0.1 W cm −3 ) and lateral (OE: 3 mW h cm −3 at power density 0.2 W cm −3 ) configurations. Experimental findings are discussed within the framework of novel and constructive dual functionality of asymmetric electrodes’ charging mechanism offer a benchmark for high‐performing next‐generation flexible microscale supercapacitors.