Unraveling the role of ionic bonding interactions in electronic properties of graphene composite aerogels to enhance piezoresistive performance

Although ionic bonding interactions have already been shown to play a crucial role in determining the electronic properties of graphene composite aerogels (GCAs), there have been vast obstacles to exploring their conductive role because of the entanglement between microstructural and interlayer interactions. In this work, we proposed a multi-step induced strategy to aid in the deblocking of this entanglement, and enabling the investigation of the conductive role for ionic bonding interactions. The combined results from the experiment and Density Functional Theory (DFT) calculations suggest that the impact of ionic bonding interactions on the electronic properties was strongly associated with the size of hydrated metal ions. A hydrated metal ion with a small diameter that may form a molecular bridge for promoting electron transport, has shown the ability to enhance the electrical conductivity of GCAs, which however showed a reverse effect for the hydrated metal ion with a large diameter due to the enlarged spacing of the graphene interlayers. Such well-defined conductive mechanisms and assisted with elaborate microstructural design, are effective for achieving unprecedented electrical conductivity (13.16 S cm−1), extremely high elasticity (20.1 kPa), and extraordinary piezoresistive performance. Our work provides insight into the role of ionic bonding interactions in GCAs as well as its potential application in future flexible-sensing devices.