“Sweat‐Driven” MXene Composites with Energy‐Storage and Thermal‐Management Multifunctions: A Platform for Versatile Electronic Skins

Abstract

Most exogenous electronic skins (e‐skins) currently face challenges of complex structure and poor compatibility with the human body. Utilizing human secretions (e.g., sweat) to develop e‐skins is an effective solution strategy. Here, a new kind of “sweat‐driven” e‐skin is proposed, which realizes energy‐storage and thermal‐management multifunctions. Through the layer‐by‐layer assembly of MXene‐carbon nanotube (CNT) composite with paper, lightweight and versatile e‐skins based on supercapacitors and actuators are fabricated. Long CNTs wrap and entangle MXene nanosheets, enhancing their long‐distance conductivity. Furthermore, the CNT network overcomes the structural collapse of MXene in sweat, improving the energy‐storage performance of e‐skin. The “sweat‐driven” all‐in‐one supercapacitor with a trilayer structure is patternable, which absorbs sweat as electrolyte and harnesses the ions therein to store energy, exhibiting an areal capacitance of 282.3 mF cm−2 and a high power density (2117.8 µW cm−2). The “sweat‐driven” actuator with a bilayer structure can be driven by moisture (bending curvature of 0.9 cm−1) and sweat for personal thermal management. Therefore, the paper serves as a separator, actuating layer, patternable layer, sweat extractor, and reservoir. The “sweat‐driven” MXene‐CNT composite provides a platform for versatile e‐skins, which achieve the interaction with humans and offer insights into the development of multifunctional wearable electronics.