Super-Stretchable and High-Energy Micro-Pseudocapacitors Based on MXene Embedded Ag Nanoparticles.

The advancement of aqueous micro-supercapacitors offers an enticing prospect for a broad spectrum of applications, spanning from wearable electronics to micro-robotics and sensors. Unfortunately, conventional micro-supercapacitors are characterized by low capacity and slopy voltage profiles, limiting their energy density capabilities. To enhance the performance of these devices, the use of 2D MXene-based compounds has recently been proposed. Apart from their capacitive contributions, these structures can be loaded with redox-active nanowires which increase their energy density and stabilize their operation voltage. However, introducing rigid nanowires into MXene films typically leads to a significant decline in their mechanical properties, particularly in terms of flexibility. To overcome this issue, we demonstrate herein super stretchable micro-pseudocapacitor electrodes composed of MXene nanosheets and in-situ reconstructed Ag nanoparticles (Ag-NP-MXene) delivering high energy density, stable operation voltage of ∼1 V, and fast charging capabilities. Careful experimental analysis and theoretical simulations of the charging mechanism of the Ag-NP-MXene electrodes reveal a dual nature charge storage mechanism involving ad(de)sorption of ions and conversion reaction of Ag nanoparticles. The superior mechanical properties of synthesized films obtained through in-situ construction of Ag-NP-MXene structure show an ultrastretchability, allowing the devices to provide stable voltage and energy output even at 100% elongation. This article is protected by copyright. All rights reserved.