Recent advances in flexible fiber-shaped metal-air batteries

Metal-air batteries in fiber shape, which are theoretically endowed with high energy densities, have emerged as a versatile platform for the advance of next-generation flexible electronics. The past decade has witnessed the booming development of fiber-shaped metal-air batteries including flexible lithium-air (oxygen) batteries, zinc-air batteries, aluminum-air batteries and lithium-CO2 batteries. Here the recent advances of fiber-shaped metal-air batteries are briefly summarized, with particular emphasis on the fabrication of flexible electrodes, the electrolyte exploitation and encapsulating material optimization. The remaining challenges and promising directions are highlighted to provide clues for the practical implementation of fiber-shaped metal-air batteries.