Low Self-Discharge Zn-Ion Battery-Type Electronic Skin for Sports Medicine Applications

Flexible electronic skins (e-skins) that integrate pressure sensing and energy storage are vital for achieving autonomous wearable systems, offering miniaturized architecture, reducing heavy wiring, and enabling static/dynamic pressure detection. However, their practical application remains restricted by severe self-discharge behavior and limited sensing performance. Here, a self-powered Zn-ion battery-type e-skin featuring low self-discharge is developed through the rational structural and electrochemical design. The device employs Zn-loaded carbon-nanotube-modified polyurethane foam (Zn@CPUF) as the anode, a dome-shaped zinc tetrafluoroborate (Zn(BF₄)₂) ionic gel electrolyte, and hot-pressed MnO₂-loaded carbon-nanotube-modified polyurethane foam (MnO₂@CPUF-HP) as the cathode. The dome-shaped electrolyte ensures point contact with the electrodes in the absence of external pressure, significantly suppressing interfacial reactions and parasitic self-discharge. Mechanical loading increases the electrode-electrolyte contact area, reducing internal resistance and enabling high pressure sensitivity of 42.5 kPa^-1. Benefiting from the gradient-structured electrodes, the device supports a wide detection range (1 Pa-3.23 MPa) and maintains excellent cycling stability over 10 000 compression cycles. The low self-discharge Zn-ion battery-type sensor enables monitoring of physiological and motion signals and supports hand function assessment and gesture recognition, underscoring its potential for practical and low-power wearable monitoring.