Advanced Fiber-Shaped Aqueous Zn Ion Battery Integrated with Strain Sensor

Multifunctional batteries have attracted increasing attention, offering additional functionalities beyond the conventional batteries. Herein, we report a fiber-shaped Zn ion battery that not only acts as a high-performance power supply but also provides a sensing function to monitor human motions. Titanium fiber coated with α-MnO₂ nanoflowers is exploited as the cathode for the fiber-shaped Zn ion battery, taking full advantage of such unique three-dimensional nanoflower structures of α-MnO₂ with a large electrochemically active surface area and fast electrochemical reaction kinetics. Thus, the obtained fiber-shaped Zn ion battery shows a high capacity of 280 mAh g^-1 at 0.1 A g^-1, resulting in a notable energy density of 396 Wh kg^-1, good stability (capacity retention of 80.6% after 300 cycles), and high flexibility. As a demonstration, an electronic watch and five LEDs are successfully driven by two fiber-shaped Zn ion batteries. Furthermore, the fiber-shaped Zn ion battery is integrated with a strain sensor based on a carbon nanotube/polydimethylsiloxane film, offering good sensitivity to monitor motions of different body parts, such as the wrist, finger, elbow, and knee. This work provides insights into multifunctional battery applications for next-generation wearable electronics.