High-voltage asymmetric MXene-based on-chip micro-supercapacitors

On-chip micro-supercapacitors (MSCs) are one of the most promising devices to be integrated into micro-/nano-scale electronic devices for offering sufficient peak power and energy support. However, low operate voltage and limited energy density greatly inhibit their wider practical application. Herein, high-voltage on-chip MSCs based on Ti3C2Tx MXene as a negative electrode and activated carbon as a positive electrode are designed and are simply manufactured via a novel cutting-spraying method. Through solving the excessive polarization of MXene, a single asymmetric on-chip MSCs can deliver a potential window up to 1.6 V in neutral electrolyte (PVA/Na2SO4), and share a high areal capacitance of 7.8 mF cm−2 (a stack specific capacitance of 36.5 F cm−3) and a greatly improved energy density of 3.5 mWh cm−3 at a power density of 100 mW cm−3, which are much higher than other on-chip energy storage counterparts. Besides, MSCs show an excellent capacity retention (remaining 91.4% after 10 000 cycles). More importantly, MSCs can be easily enlarged as highly integrated array in series and/or in parallel on the silicon wafers. Evidently, this study opens up new avenues for developing high-voltage MXene-based MSCs used in on-chip electronics and portable devices.