Fiber-shaped aqueous battery: Design, advancements, and perspectives

To meet t the growing demand for safe, flexible, and environmentally friendly energy storage in wearable electronics, fiber-shaped aqueous batteries (FABs) have emerged as a key research focus. This article systematically reviews recent advances in FABs, beginning with their fundamental mechanisms: intercalation, conversion, and deposition/dissolution of ions. It then outlines design strategies across electrode fabrication (e.g., coating, in-situ growth, spinning), device configurations (parallel, twisted, coaxial, crossing), and key performance metrics such as energy density and cycling stability. The progress of FABs based on Li+/Na+, multivalent ions (Zn²⁺/Mg²⁺/Ca²⁺/Al³⁺), NH₄⁺, and alkaline electrolytes is summarized, along with integrated applications in photo-response, sensing, and multi-device power systems. Finally, the review highlights persistent challenges like low material utilization and interfacial instability, and envisions future developments in smart materials, advanced manufacturing, and standardization—providing valuable insights for next-generation flexible energy storage technologies.