Bifunctional polyoxometalate clusters-modified single-walled carbon nanotubes for high-energy–density micro-supercapacitors

Abstract

The rapid advancement of wearable electronics has pushed the urgent demand for flexible power sources with high energy density and fast integrations. Herein, we created high-energy–density micro-supercapacitors (MSCs) based on phosphomolybdic acid (PMo12) clusters anchored single-walled carbon nanotubes (SWCNTs) via the electrostatic assembly. The SWCNT microelectrodes for MSCs were directly fabricated by an aerosol process without any solvent-based treatment. The PMo12 clusters were found to not only increase the electrical conductivity of SWCNT thin-film electrodes, but also offer significant pseudo-capacitance of MSCs. The MSCs based on PMo12-modified SWCNTs demonstrated an areal capacitance of 10.2 mF cm−2 when scanned at 5 mV s−1, coupled with a notable energy density of 0.71 μWh cm−2 at a power density of 7 μW cm−2, being much higher than the one without PMo12 modification. The density functional theory simulation further reveals the enhancement of electrical conductivity and areal capacitance induced by PMo12 modifications. Moreover, our strategy is highly scalable for integrations via series or parallel connections, which could deliver higher voltage output or areal capacitance. This work demonstrates great potential for high-performance MSCs toward wearable electronics applications.