Screen-printable microscale hybrid device based on MXene and layered double hydroxide electrodes for powering force sensors

Coplanar energy storage devices with interdigitated electrodes have attracted a significant amount of attention as micropower units for portable and flexible electronics, and self-powered systems. Herein, we propose a simple, cost-effective, and scalable two-step screen-printing process to fabricate flexible coplanar asymmetric microscale hybrid device (MHD) with a higher energy density compared to carbon-based microsupercapacitors. 2D titanium carbide MXene (Ti3C2Tx) with a large inlayer spacing is selected as negative electrode, and Co-Al layered double hydroxide (LDH) nanosheets are selected as positive electrode. The assembled coplanar, all-solidstate, asymmetric MHD possesses a higher energy density (8.84 mu Wh cm(-2)) compared to the MXene-based, coplanar, symmetric microsupercapacitors (3.38 mu Wh cm(-2)), and exhibit excellent flexibility and reliability, as well as cycling stability (92% retention of the initial capacitance after 10,000 cycles). Moreover, we integrate the coplanar asymmetric MHDs with the force sensing resistors as portable power source units to fabricate lightweight and inexpensive integrated force sensors, which can be used to detect applied pressure variation. The two-step screen-printing method can also be extended to other MXenes and various positive electrode materials for fabrication of coplanar asymmetric MHDs on flexible substrates. Therefore, we believe that the two-step screen-printing method opens up new avenues toward developing flexible coplanar asymmetric MHDs, thus promoting the application of MHDs based on MXenes for flexible integrated electronic devices.