Cathode-Free Aqueous Micro-battery for an All-in-One Wearable System with Ultralong Stability

Abstract

Constructing an all-in-one wearable electronic system integrated with an energy-harvesting, an energy-storing, and a working unit can fundamentally solve the problems of sustainable energy supply, miniaturization, and lightweight for further commercialization. Here, an all-in-one wearable system consisting of solar cell, cathode-free zinc ion micro-battery (ZIMB) and piezoresistive pressure sensor is proposed, achieving an ultralong and stable power supply. Under the action of photocurrent, this integrated system is stimulated to in situ generate MnO₂ on the initial cathode-free substrate, meanwhile converts into chemical energy for powering the sensor, which eliminates prepreparation and treatment of the cathode for energy storage units. The facial cathode-free ZIMB combining the all-in-one design enhances matching degree between different units and improves the integration. The working mechanism of the cathode-free ZIMB is analyzed systematically through multiple ex situ characterizations and density functional theory (DFT) simulation. And the integrated sensing system illuminating for 12.0 h realizes the ultralong energy supply of the pressure sensor up to 150 000 cycles. As a concept, the integrated wearable electronic is used to detect human physiological signals, showcasing potential applications in activity monitoring, intelligent robotics, human–computer interaction, and other related fields.