3D Printed Flexible Zinc-Ion Battery for Real-Time Health Monitoring Devices

The growing need for multifunctional wearable electronics for mobile applications has triggered the demand for flexible and reliable energy storage devices. 3D printing technology has emerged as a promising and attractive method for manufacturing these devices. This study presents the design and fabrication of a flexible quasi-solid-state Zn-ion battery using the direct-writing 3D printing technique. A conductive silver paste with high conductivity was printed onto a PET substrate to serve as the current collector. The cathode was fabricated from carbon-coated MnO₂ nanorods produced using hydrothermal methods, while the anode consisted of commercial zinc powder. The cathode and anode slurries exhibiting excellent viscoelasticity were 3D printed on the current collector. To complete the flexible quasi-solid-state zinc-ion battery, a PVA gel electrolyte was printed onto the PET substrate. This battery delivered an initial capacity of 267.3 mAh g^-1 and maintained a capacity of 189.7 mAh g^-1 after 500 cycles at a current density of 0.2 A g^-1. Furthermore, the 3D printed battery successfully powered a portable human heart rate sensor, showcasing the potential of 3D printing technology as an environmentally friendly, cost-effective, and scalable solution for wearable energy storage devices.