X. Wang, W.W. Chen, X.Y. Shi, P. Das, S.H. Zheng, J.H. Qin*, C.L. Sun, Z.-S. Wu*

Advanced Energy Materials, 2023, 13.

DOI: 10.1002/aenm.202203535 [PDF]

The rapid development of smart wearable microdevices has stimulated the urgent demand for micro-supercapacitors (MSCs) with multiple form factors, however, several factors like conventional bulky stacked geometries, rigid substrates and complex manufacturing processes have blocked their path towards practical application. Herein, a microfluidics-assisted fabrication strategy is demonstrated which utilizes capillary action for precisely customising planar MSCs, showing substrate-free configuration attributed to the use of polyvinyl alcohol hydrogel in both electrolytes and transfer template. Remarkably, the resulting MSCs with highly conductive polymer (PEDOT:PSS) -based active materials as microelectrodes, exhibit excellent areal capacitance of 21.4 mF/cm2 and noticeable capacitance retention of 88% after 10000 cycles. Furthermore, the substrate-free MSCs display extraordinary flexibility and remarkable stretchability of 640% strain. We also demonstrate significant serial and parallel integration for boosting voltage and capacitance output, demonstrative of impressive performance uniformity and applicability for different scenarios. Therefore, the exploration of microfluidics-assisted fabrication is a reliable strategy for high performance standalone microelectronics with in-plane configuration.