Deformation-tolerant metal anodes for flexible sodium-air fiber batteries

Although flexible sodium-air(Na-air)batteries with high theoretical energy density offer promising opportunities for next-generation smart electronics,enhancing the safety and efficiency of flexible sodium metal anodes under dynamic and continuous deformation remains a challenge.Here,a flexible sodiated carbon nanotube layer to suppress dendrite growth under various deformations is demonstrated through a Fermi level-driven spontaneous synthetic process.The resulting sodiated carbon nanotube layer,which has a spontaneously formed solid-electrolyte interface and a robust interlocked structure,creates a uniformly distributed electric field and stable interface even under deformation,affording dendrite-free flexible Na metal anodes.With this deformation-tolerant Na metal anode,we have constructed a new family of highly flexible Na-air fiber batteries with excellent cycling performance for 400 cycles at a current density of 1000​mA·g^(−1) and a capacity limit of 500 mAh·g^(−1) under dynamic deformation.These Na-air fiber batteries can be further woven into self-powering systems to support flexible electronic devices.