In situ formation of Co 3 O 4 nanocrystals embedded in laser-induced graphene foam for high-energy flexible micro-supercapacitors.

The cost-effective synthesis of flexible energy storage devices with high energy and power densities is a challenge in wearable electronics. Here, we report a facile, efficient, and scalable approach for preparing three-dimensional (3D) laser-induced graphene foam (Co 3 O 4 @LIG) embedded with porous Co 3 O 4 nanocrystals using a CO 2 infrared laser. The in situ formed Co 3 O 4 @LIG nanocomposites directly serve as active materials, current collectors, and the conductive substrate for micro-supercapacitors (MSCs). Benefiting from rational structural features, the MSC based on Co 3 O 4 @LIG nanocomposites (Co 3 O 4 @LIG-MSC) with an interdigitated electrode configuration exhibits excellent electrochemical performance, including a high specific capacitance (143.5 F g -1 ), excellent rate capability, high energy density (19.9 W h kg -1 at a power density of 0.5 W kg -1 ), and remarkable power density (15.0 W kg -1 at an energy density of 15.8 W h kg -1 ). Furthermore, the device possesses good stability under different bending diameters and cycling stability. Such a highly integrated flexible MSC with high energy and power densities made by a directly laser scribing strategy has some potential for the fabrication of wearable energy storage devices.