Cathode-less zinc-manganese fiber batteries with reinforced-concrete structured composite hydrogel electrolytes

Flexible fiber batteries, an essential component of wearable technology, hold the promise of significant progress with the development of high-safety zinc-manganese (Zn-Mn) fiber batteries. To counteract the issues of inadequate electrochemical performance and low voltage of Zn-Mn fiber batteries, we present a dual-strategy featuring a unique composite hydrogel electrolyte and a cathode-less design. The electrolyte, with a reinforced-concrete structure, optimizes the interaction with Zn 2+ ions, accelerating Zn 2+ ion transport, and suppressing HER and Zn dendrite growth. The resulting fiber batteries offer an outstanding energy density of 227.08 mWh cm −3 , double that of the reported Zn-ion fiber batteries, with a high capacity of 156.48 mAh cm −3 and 76.5 % retention after 2700 cycles. The cathode-less design enhances the deposition/dissolution of Zn 4 SO 4 (OH) 6 · x H 2 O, boosting the operating voltage to 1.9 V. The fiber batteries exhibit excellent adaptability, maintaining operation after washing or cutting, and they integrate seamlessly into textiles for a health tracking system, marking a significant advancement in smart fabric technology for wearable devices.