Scalable, Self-Aligned Printing of Flexible Graphene Micro-Supercapacitors

Graphene micro-supercapacitors (MSCs) are an attractive energy storage technology for powering miniaturized portable electronics. Despite considerable advances in recent years, device fabrication typically requires conventional microfabrication techniques, limiting the translation to cost-effective and high-throughput production. To address this issue, we report here a self-aligned printing process utilizing capillary action of liquid inks in microfluidic channels to realize scalable, high-fidelity manufacturing of graphene MSCs. Microstructured ink receivers and capillary channels are imprinted on plastic substrates and filled by inkjet printing of functional materials into the receivers. The liquid inks move under capillary flow into the adjoining channels, allowing reliable patterning of electronic materials in complex structures with greatly relaxed printing tolerance. Leveraging this process with pristine graphene and ion gel inks, miniaturized all-solid-state graphene MSCs are demonstrated to concurrently achieve outstanding resolution (active footprint: <1 mm(2), minimum feature size: 20 mu m) and yield (44/44 devices), while maintaining a high specific capacitance (268 mu F cm(-2)) and robust stability to extended cycling and bending, establishing an effective route to scale down device size while scaling up production throughput.