Hyperelastic aerogels with anisotropic layer-strut cellular structure for piezoresistive sensor and compressible supercapacitor applications

The elastic composite aerogels based on two-dimensional transition metal carbides/nitrides/carbonitrides (MXene) hold significant potential as high-performance multifunctional materials for sensors and energy storage devices, but they are still plagued by the issues of brittleness and unsatisfactory conductivity. Herein, aiming to address these problems,we have combined Ti3C2TX MXene with poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) as a conductive adhesive and spring -like carbon nanocoils (CNCs) as crosslinking chains to construct hyperelastic aerogels through the directional freeze-casting technique. The MXene/ PEDOT:PSS/CNC aerogels feature an anisotropic layer-strut cellular structure. Benefiting from this unique structure, the aerogels exhibit impressive mechanical property, achieving a maximum resilient strain of 80 % (corresponding 64.3 kPa). The piezoresistive sensors based on the aerogels perform a high sensitivity of 0.23 kPa-1, a low detection limit of -45 Pa, and a stable long-term sensing of over 5000 cycles. The aerogels can also work as excellent electrode materials, displaying a high specific capacitance of 134.5 F g-1 at 0.5 A g-1 and superior rate performance. Furthermore, the assembled compressible supercapacitor shows stable electrochemical performance with compressive strain increasing from 0 to 80 %. The designed MXene/PEDOT:PSS/CNC aerogels are expected to serve as novel multifunctional platforms for thermal insulation, shock absorption, sensitive strain detecting, and highly stable compressive energy storage.