3D printing of serrated NiCo2S4-based electrodes for wearable micro-supercapacitors

The application of 3D printing technology in fabricating quasi-solid-state micro-supercapacitors (MSCs) offers inherent benefits in programmable structural design and high-mass-loading electrode fabrication. Nevertheless, the absence of high-performance printable inks and the sluggish ion transport within thick electrodes present significant challenges to their practical charge storage capabilities. Here, a new NiCo 2 S 4 -based nanocomposite ink with excellent rheological properties has been successfully developed and the 3D structure of quasi-solid-state MSCs is rationally engineered through the direct-ink-writing 3D printing technology. Beneficial from the firmly anchored NiCo 2 S 4 nanoparticles on the reduced graphene oxide (rGO) and the ordered 3D micropores, the thick electrodes with serrated architectures provide abundant reaction sites and exhibit enhanced ion transport. Consequently, the MSCs with triple-layer-serrated electrodes can deliver a high areal capacitance up to 416.7 mF cm −2 . In comparison to the latticed counterparts, the areal capacitances of serrated MSCs with single-, double-, and triple-layer electrodes are amplified by 127.1%, 349.8%, and 585.9%, respectively (under 1 mA cm −2 ). This study offers novel insights into the cross-scale design of materials and electrode architectures for quasi-solid-state MSCs with high areal capacitance, promoting their integration into flexible and portable electronic devices.