Facile fabrication of copper-based metal-organic-framework/graphene hybrid supported on highly stretchable wooden substrate for in-plane micro-supercapacitor with potential applications as wearable devices

Abstract

The rise in demand for flexible power sources in the application of portable and wearable devices has highlighted the importance of micro-supercapacitors (MSCs) due to their preferred features, including high power density and ultrastability. Although a wide range of active materials is available, developing cost-effective fabrication methods using flexible substrates and innovative materials is still challenging. In this work, in-plane interdigitated MSCs were developed using exfoliated graphene oxide (EGO) and a Cu-based metal-organic framework (Cu-MOF) hybrid by a facile stamping method on a flexible wood substrate. This was followed by a reduction state of EGO by nascent hydrogen. The flexible substrate was created through lignin modification and infiltration of Balsa wood sheet. The hybrid material with an equal weight percentage of Cu-MOF and EGO demonstrated significant electrochemical performance, which is explained by the synergistic interaction between the hybrid's components, resulting from the porous structure and high surface area of Cu-MOF along with plentiful active sites and electrical conductivity offered by EGO. The fabricated MSC of the hybrid material exhibited suitable areal capacitance and energy density of 5.75 mF cm^-2 and 0.798 µWh cm^-2, respectively, at a current density of 0.09 mA cm^-2. Moreover, it also showed an outstanding capacitance retention of 93 % after 2000 cycles. The results indicate that the MSC, prepared from the hybrid with the same ratio of each component, has the potential to serve as an efficient energy storage device for wearable and flexible miniaturized applications.