One Step Deposition of PEDOT–PSS on ALD Protected Silicon Nanowires: Toward Ultrarobust Aqueous Microsupercapacitors

Herein, we propose a fast and simple deposition method of a highly robust pseudocapacitive material based on a straightforward drop-cast of a commercial PEDOT:PSS solution onto 3 nm alumina-coated silicon nanowires. The composite material produced (PPSS-A@SiNWs) displays, remarkable capacitive behavior with a specific capacitance of 3.4 mF·cm–2 at a current density of 2 A·g–1 in aqueous Na2SO4 electrolyte. Moreover microsupercapacitor (MSC) devices based on this material exhibits outstanding lifetime capacity retaining 95% of its initial capacitance after more than 500 000 cycles at a current density of 0.5 A·g–1, a specification which exceeds by far most of the stability of conducting polymers previously reported in the literature. In term of pure energy storage performances, the system is able to reach excellent specific energy and power values of 8.2 mJ·cm–2 and of 4.1 mW·cm–2, respectively, at a high current density of 2 A·g–1. Results are systematically compared to both the state-of-the-art silicon based aqueous on-chip supercapacitors and to that of the pristine alumina-coated silicon nanowires (A@SiNWs) to highlight the contribution of the conductive PEDOT:PSS polymer (PPSS in this study). Hence, the aforementioned one-step deposition represents a simple, cheap and scalable method to thoroughly increase the cycling stability of a well-known conductive polymer, PEDOT–PSS, while drastically increasing the electrochemical performances of an existing technology, the Si NW-based MSCs using aqueous electrolytes.