Programmable patterning fabrication of laser-induced graphene-MXene composite electrodes for flexible planar supercapacitors

The development of laser-induced graphene (LIG) has been regarded as an effective method for satisfying the substantial requirements for the scalable fabrication of graphene-based electrode materials. Despite the rapid progress in fabricating LIG-based supercapacitors, the incompatibility between material modification and the device planarization process remains a challenging problem to be resolved. In this study, we demonstrate the attributes of novel LIG-MXene (LIG-M) composite electrodes for flexible planar supercapacitors fabricated by direct laser writing (DLW) of MXene-coated polyimide (PI) films. During the DLW process, PI was transformed into LIG, while MXene was simultaneously introduced to produce LIG-M. Combining the porous structure of LIG and the high conductivity of MXene, the as-prepared LIG-M-based supercapacitor exhibited superior specific capacitance, five times higher than that of the pristine LIG-based supercapacitor. The enhanced capacitance of LIG-M also benefited from the pseudocapacitive performance of the abundant active sites offered by MXene. Moreover, the planar LIG-M-based device delivered excellent cycling stability and flexibility. No significant performance degradation was observed after bending tests. Arbitrary electrode patterns could be obtained using the DLW technique. The patterned in-series LIG-M supercapacitor was able to power a light-emitting diode, demonstrating significant potential for practical applications.