Natively stretchable micro-supercapacitors based on a PEDOT:PSS hydrogel

Stretchable micro-supercapacitors (MSCs) with high power density and small size have been intensively researched in the recent years. However, to date, the stretchability of the overall device is still limited by the lack of a stretchable electrode material, which results in significant performance degradation, particularly in the highly stretched state. Herein, a new method for designing natively stretchable MSCs capable of maintaining high electrochemical performance in a highly (200%) stretched state is presented. The electrode is based on the novel incorporation of the bis(trifluoromethane) sulfonamide lithium salt (LiTFSI) and poly(vinyl alcohol) (PVA) into a PEDOT:PSS hydrogel. The resultant PEDOT:PSS-LiTFSI-PVA hydrogel is operated with a PVA/H₂SO₄ electrolyte to deliver an unprecedented level of combined performance such as a large areal capacitance of 44.5 mF cm⁻², a power density of 0.04 mW cm⁻² at an area energy density of 0.004 mW h cm⁻², and an excellent stretchability of 200% while retaining 93% of the original capacitance. The MSCs deliver highly stable performance even under extensive stretching, showing a high 92% capacitance retention after 2000 cycles of 100%-strain stretching. The proposed MSC architecture is compatible with laser patterning, which enables rapid fabrication, and reflects a highly practical approach for realizing high performance, mechanically robust micro energy storage devices.