LAUSR

Despite the advantages of the fiber‐shaped Zn‐ion microbattery (FZMB) in powering wearable electronics, several fundamental challenges hinder its practical application, mainly including dendrite growth on Zn anodes (leading to short cycle life) and low electrical conductivity of cathode (resulting in poor rate performance). Herein, a facile approach of sputtering a nano‐thin conductive carbon layer on Zn anode to effectively suppress dendrite growth and a dual‐conductive polymer strategy to fabricate ultraconductive core‐sheath fiber cathode (poly(3,4‐ethylenedioxythiophene)‐poly(styrene sulfonate) (PEDOT:PSS) fiber@polyaniline nanobulges) are demonstrated. The carbon layer suppresses Zn dendrites by uniformizing surface electric field and providing abundant nucleation sites. The superior conductivity of the cathode is inherited from two conductive polymers (in particular, PEDOT:PSS fibers have an ultrahigh conductivity of 3676 S cm−1) and their strong intermolecular interactions. The resulting FZMB shows excellent stability (over 100% capacity retention after 3000 cycles) and supercapacitor‐level rate performance (73% capacity retention from 0.1 to 10 A g−1). Kinetics and mechanism studies reveal that the surface‐controlled dual‐ion migration mechanism is also correlated with the high rate performance. The corresponding quasi‐solid‐state device exhibits high stability under extreme deformation conditions and superior water‐proof capability (94.6% capacity retention after 12 h underwater immersion), demonstrating great practical application potential.