# Scalable production of graphene inks via wet-jet milling exfoliation for screen-printed micro-supercapacitors

## TL;DR

This paper presents a scalable wet-jet milling method to produce graphene inks for flexible, waterproof micro-supercapacitors with high capacitance, stability, and suitability for wearable electronics.

## Contribution

It introduces a cost-effective, high-throughput exfoliation process for graphene and demonstrates its application in screen-printed, flexible, and washable micro-supercapacitors.

## Key findings

- Achieved high areal and volumetric capacitance in printed MSCs.
- Demonstrated excellent cycling and mechanical stability.
- Produced waterproof MSCs suitable for wearable devices.

## Abstract

The miniaturization of energy storage units is pivotal for the development of next-generation portable electronic devices. Micro-supercapacitors (MSCs) hold a great potential to work as on-chip micro-power sources and energy storage units complementing batteries and energy harvester systems. The scalable production of supercapacitor materials with cost-effective and high-throughput processing methods is crucial for the widespread application of MSCs. Here, we report wet-jet milling exfoliation of graphite to scale-up the production of graphene as supercapacitor material. The formulation of aqueous/alcohol-based graphene inks allows metal-free, flexible MSCs to be screen-printed. These MSCs exhibit areal capacitance (Careal) values up to 1.324 mF cm-2 (5.296 mF cm-2 for a single electrode), corresponding to an outstanding volumetric capacitance (Cvol) of 0.490 F cm-3 (1.961 F cm-3 for a single electrode). The screen-printed MSCs can operate up to power density above 20 mW cm-2 at energy density of 0.064 uWh cm-2. The devices exhibit excellent cycling stability over charge-discharge cycling (10000 cycles), bending cycling (100 cycles at bending radius of 1 cm) and folding (up to angles of 180{\deg}). Moreover, ethylene vinyl acetate-encapsulated MSCs retain their electrochemical properties after a home-laundry cycle, providing waterproof and washable properties for prospective application in wearable electronics.

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Source: https://tomesphere.com/paper/1903.08965