A Universal Strategy for Synthesis of Large‐Area and Ultrathin Metal Oxide/rGO Film Towards Scalable Fabrication of High‐Performance Wearable Microsupercapacitors

Abstract High‐performance wearable microsupercapacitor (MSC) as energy storage components is highly desirable for developing self‐powering wearable electronics. However, synthesis of MSC electrode film concurrently possessing large area, ultrathin thickness, and high areal energy storage capability is still challenging. Herein, a universal strategy is reported to synthesize large‐area and ultrathin metal oxide nanoparticles (MONPs)/reduced graphene oxide (rGO) hybrid‐structured films by attaching self‐assembled film of a wide range of MONPs onto self‐assembled rGO film and subsequent carbonization. Combining a template‐assisted patterning strategy and a floating film salvaging process, flexible symmetric and asymmetric MSCs based on MONPs@C/rGO films can be easily prepared in large areas. MONP agglomeration is avoided and its pseudocapacitive behavior is well utilized, thereby realizing a high areal specific capacitance of 9.32 mF cm −2 in Fe 3 O 4 @C/rGO‐based symmetric MSC at a film thickness of only 275 nm, corresponding to a high volumetric specific capacitance of 338.9 F cm −3 . Moreover, the MnO@C/rGO‖Fe 3 O 4 @C/rGO‐based asymmetric MSC delivers a high volumetric energy density of 69.8 mWh cm −3 . The MSCs also demonstrate their efficient power supply in wearable self‐powering systems. This work provides a new route for scalable preparation of high‐performance wearable MSCs, and also enables customizable fabrication and performance tuning of MSCs.