Anode‐Free Sodium Metal Batteries Based on Nanohybrid Core–Shell Templates

Abstract Anode‐free sodium metal batteries (AF‐SMBs) can deliver high energy and enormous power, but their cycle lives are still insufficient for them to be practical as a power source in modern electronic devices and/or grid systems. In this study, a nanohybrid template based on high aspect‐ratio silver nanofibers and nitrogen‐rich carbon thin layers as a core–shell structure is designed to improve the Coulombic efficiency (CE) and cycling performance of AF‐SMBs. The catalytic nanohybrid templates dramatically reduce the voltage overshooting caused by metal nucleation to one‐fifth that of a bare Al foil electrode (≈6 mV vs ≈30 mV), and high average CE values of >99% are achieved over a wide range of current rates from 0.2 to 8 mA cm −2 . Moreover, exceptionally long cycle lives for more than 1600 cycles and an additional 1500 cycles are achieved with a highly stable CE of >99.9%. These results show that AF‐SMBs are feasible with the nanohybrid electrode system.