Fabrication of Hybrid Supercapacitor by MoCl5 Precursor‐Assisted Carbonization with Ultrafast Laser for Improved Capacitance Performance

Abstract Hybrid supercapacitors use electric double‐layer capacitance and Faradaic pseudocapacitance as energy storage mechanisms. This type of supercapacitor is becoming a prime candidate for next‐generation energy storage devices, with advantages in terms of energy density, specific capacitance, and life cycle. However, reducing the electrode area and increasing the specific capacitance of hybrid supercapacitors remain challenging. In this study, a MoCl 5 Precursor‐assisted Ultrafast Laser Carbonization (MPAULC) method to fabricate symmetric hybrid supercapacitors with improved capacitance and reduced size is proposed. The method uses an ultrafast laser to induce the formation of carbon/MoO 3 composite with the assistance of the MoCl5 precursor. This ultrafast laser carbonization method exhibited high processing precision. The role of the precursor in laser processing is studied using time‐resolved imaging and temperature calculations. The specific area capacitance of the C/MoO 3 hybrid supercapacitor is 11.85 mF cm −2 , 9.2 times higher than that of the laser‐induced carbon supercapacitor without precursor. The MPAULC method provides a reliable pathway for fabricating miniaturized hybrid supercapacitors with carbon/metal oxide composite electrodes on polymer substrates.