Flexible Harsh environment micro supercapacitors using direct-write 2D transition metal carbides

Abstract

2D transition metal carbides (MXenes) materials have drawn great interests for supercapacitor applications due to their unique properties, such as metallic conductivity and large specific surface areas. However, it is rather difficult to fabricate MXenes by using the process from the MAX phase, which requires a high temperature and HF etching processes. Here, we demonstrate a direct-write and fast conversion of molybdenum carbide from the Mo ions polymer composite on top of a flexible polymer substrate by an infrared laser beam. XRD results validate that the material is successfully converted to Mo ₃ C ₂ . The as converted Mo ₃ C ₂ has highly porous, 3D sponge-like structure generated by the localized heating effects. Preliminary testing results show that a micro supercapacitor using as-fabricated Mo ₃ C ₂ as electrodes has a high measured specific capacitance of 50 F/g. Electrochemical tests of flexible micro supercapacitors at both low and high temperatures from -20 to 300 °C have shown repeatable and stable performances. This laser conversion method has great potential for ultra-fast and low-cost synthesis of transition metal carbides material and the Mo ₃ C ₂ -based micro supercapacitor provides a promising alternative for harsh environment applications.