Deep eutectic solvent-infused two-dimensional metal–organic framework membranes as quasi-solid-state electrolytes for wearable micro-supercapacitors

Abstract

The burgeoning field of miniaturized and portable electronic devices calls for novel advances in micro-energy storage technology. Micro-supercapacitors (MSC) stand at the forefront of this endeavour, yet unlocking their full potential necessitates the exploration of high-performance electrolytes. Herein, we introduce a strategy that leverages flexible metal–organic framework (MOF, CuTCPP) nanosheet-based membranes to construct quasi-solid-state electrolytes (QSSEs) and enhance the ionic conductivity and electrochemical performance of deep eutectic solvent (DES)-based MSCs. Owing to the multiple nanochannel pathways provided by the porous MOF nanosheets, the ionic conductivity of DES within the nanochannels exhibits a 13-fold increment compared with its bulk counterpart. Furthermore, we engineered MSC harnessing the CuTCPP–DES system, whose performance surpasses that reported for most of the ionic liquid and 2D material-based MSCs. The areal-specific capacitance was 81.3 mF cm⁻² at a current density of 0.1 mA cm⁻², and the energy density was 45.17 μW h cm⁻² at a power density of 8.559 mW cm⁻². Notably, the performance of MSCs remains consistent and unaffected, even when subjected to bending. These findings contribute to the exploration and potential optimization of the inherent benefits of MOFs, thereby presenting a paradigm shift in nanoconfined systems for microscale energy storage applications.