Micro-supercapacitors (MSC) are fastest energy storage devices with high power density and superior durability, which makes them useful in various applications such as small consumer electronics, electric vehicles and stationary grids.¹ A lot of performance discrepancies are reported earlier in many developed supercapacitor’s electrode material, few of them are discussed as: lower conductivity of the active material, less porosity in the structure, scale up issues, stability problem due to use of metals as current collector, slow ionic dynamics in sandwich configuration and many more. To overcome above issues, considerable efforts have been devoted for the development of a metal –free current collector of favorable cost and electrochemically stable material in both the electrode and current collector.² Considering carbon based materials as an efficient candidate due to its unique structural, electrical and optical properties and would be an innovative work to produce the current collector from a carbon material, which is lightweight as well corrosion free in an aqueous electrolyte.³ Therefore, we approached towards reduced graphene oxide (rGO) acquiring sufficient conductivity to replace metals and utilise it as an active material as well as charge collector in planar microsupercapacitor application.

In this work, we have grown reduced graphene oxide film on three dimensional network of Copper foam (Cuf@Cu) via single-step electrochemical deposition method (Fig. 1a). The as-developed film transferred over polyethylene terephthalate (PET) sheet, named as “ErGO@PET” and patterned in planar interdigitated finger electrodes as shown in Fig. 1a. The cyclic voltammetry (CV) and Galvanostatic charge-discharge (GCD) response shows perfect electric double layer capacitance (Fig. 1b-d) and delivers 80% capacitance even at a very high scan rate of 200 mV s^-1 (Fig. 1e).The as fabricated ErGO-MSC delivers a specific capacitance of 1.7 mF cm^-2 at a scan rate of 10 mV s^-1, an energy density of 487 μWh cm^-2 and a power density of 0.877 W cm^-2 (Fig. 1f), respectively in aqueous gel electrolyte (PVA-H₃PO₄). These results give deep insights to enhance the storage properties by unique porosity and extreme conductivity of the material in storage applications.

Acknowledgement: NK acknowledges INST, Mohali for providing fellowship and instrumentation support. This work was financially supported by DST SERB (CRG/2020/005683).

References:

1 T. Purkait, G. Singh, D. Kumar, M. Singh and R. S. Dey, Sci. Rep., 2018, 8, 1–13.

2 M. Wu, Y. Li, B. Yao, J. Chen, C. Li and G. Shi, J. Mater. Chem. A, 2016, 4, 16213–16218.

3 N. Kamboj, T. Purkait, M. Das, S. Sarkar, K. S. Hazra and R. S. Dey, Energy Environ. Sci., 2019, 12, 2507–2517.