Rational design of a high performance all solid state flexible micro-supercapacitor on paper

Micro-supercapacitors have attracted considerable attention due to their feasibility as power supplies for future integration into autonomous and portable devices. However, the conventional lab-on-chip fabrication method requires multiple patterning and metallization procedures, while the rigid substrate restricts versatility in applications such as flexible and wearable electronics. Here, we report the low cost, facile and scalable fabrication process of an all solid state flexible micro-supercapacitor on commercially available photo paper for the first time. Three dimensional interconnected coral-like polyaniline–manganese oxide composite material is electrochemically deposited on the interdigital finger electrodes. Electrochemical measurements reveal that the high aspect ratio finger electrode pattern and small gap interdigital finger electrode design is crucial to ensure superior performance. The optimized device shows an ultra high areal energy density of 6.3 μW h cm−2 at a power density of 35 μW cm−2 (94.73 mF cm−2 at 0.1 mA cm−2), while it maintains 4.8 μW h cm−2 at a power density of 3500 μW cm−2 (71.43 mF cm−2 at 10.0 mA cm−2). Meanwhile, it also has good flexibility. Such a flexible micro-supercapacitor is promising for future applications in lightweight, wearable or foldable electronics.