High Performance 2D Micro-Supercapacitor Electrode Composed of Graphene with Polydopamine As Inserts

Over the last years, graphene is deemed as one of the most promising electrode materials for EDLCs due to its large specific surface area (2600 m²·g^-1), high theoretical specific capacitance (550 F·g^-1) and high conductivity.¹ Among all the reported approaches to achieve a graphene-like material, the most favorable route is the reduction of GO and notably the electrochemical reduction of GO that is viewed as an economic, simple, fast and eco-friendly method with production possibility at a relatively large scale.^2,3 However, reduced graphene oxide (rGO) suffers from the small surface area due to the partial re-stacking of graphene sheets.⁴ Therefore, it is necessary to develop an effective and feasible route to avoid rGO re-stacking to obtain graphene-based electrodes with a high specific capacitance and a good stability.

Herein, we report graphene-polydopamine (PDA) composites as electrodes for micro-supercapacitor devices fabricated by a facile electrochemical approach. ⁵ We particularly address the rGO re-stacking issue by exploiting the PDA as a "chemical insert" between the graphene sheets but also explore the impact of PDA on the interfacial charge storage properties and the cycling performance. The optimized ERGO-PDA electrode possesses combined features of excellent capacitive behavior: high gravimetric and volumetric capacitances (178 F·g^-1 and 297 F·cm^-3, respectively, at 10 mV·s^-1). Even at a scan rate of 1V/s, its volumetric capacitance is still as high as 94 F/cm³ (versus only 39 F/cm³ for ERGO) with an excellent cycling stability. Additionally, the electrochemical quartz crystal microbalance analyses demonstrate a dominant cationic charge compensation and a very efficient interfacial transfer characteristics, since a totally reversible mass response during charge/discharge was observed for the optimized ERGO-PDA electrode. Here the favourable impact of PDA is shown to tackle rGO restacking issue, shedding light on the design of graphene based composite electrodes and can also be extended to other 2D materials for high performance electrochemical energy storage electrodes.

Keywords: EDLC, reduced graphene oxide, polydopamine, composite, microsupercapacitor.

References:

1. Tan, Y. B.; Lee, J.-M., Graphene for supercapacitor applications. J. Mater. Chem. A 2013, 1, 14814-14843.

2. Gao, W.; Debiemme-Chouvy, C.; Lahcini, M.; Perrot, H.; Sel, O., Tuning Charge Storage Properties of Supercapacitive Electrodes Evidenced by In Situ Gravimetric and Viscoelastic Explorations. Anal. Chem. 2019, 91, 2885-2893.

3. Guo, H.-L.; Wang, X.-F.; Qian, Q.-Y.; Wang, F.-B.; Xia, X.-H., A Green Approach to the Synthesis of Graphene Nanosheets. ACS Nano 2009, 3, 2653-2659.

4. Banda, H.; Périé, S.; Daffos, B.; Taberna, P.-L.; Dubois, L.; Crosnier, O.; Simon, P.; Lee, D.; De Paëpe, G.; Duclairoir, F., Sparsely Pillared Graphene Materials for High-Performance Supercapacitors: Improving Ion Transport and Storage Capacity. ACS Nano 2019, 13, 1443-1453.

5. Bouzina, A.; Perrot, H.; Sel, O.; Debiemme-Chouvy, C., Preventing Graphene from Restacking via Bioinspired Chemical Inserts: Toward Superior 2D Micro-Supercapacitor Electrode Performance. ACS Appl. Nano Mater. 2021, DOI : 10.1021/acsanm.1c00489.

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