Heterostructured hollow fibers stitched together from nickel sulfides capped S, N-codoped carbon nanotubes as a trifunctional electrode for flexible hybrid Zn batteries

The explorations of highly performance cathodes are the key concerns of hybrid Zn batteries (HZBs) that combine the Zn-ion (ZIBs) and Zn-air (ZABs) batteries. Herein, a freestanding hollow fiber stitched by the heterostructures of S, N-codoped carbon nanotubes (SNCNT) confined nickel sulfides (Ni3S2) nanoparticles are designed as a trifunctional electrode for HZB. The nickel sulfide nanoparticles are encapsulated by in-situ grown S, N-codoped carbon nanotubes, which stitch together to assemble the hollow fibers. Their highly porous and conductive frame gives fast electron/ion pathways and abundant active sites. The interaction between Ni3S2 and SNCNT favors the OER catalytic properties and the S, N-codopant in SNCNT endows ORR activities in the heterostructured unit. Both experimental and theoretical results demonstrate the Ni3S2@SNCNT hollow fiber is a trifunctional and flexible electrode with high OER/ORR electrocatalytic activities and superior electrochemical properties. The hybrid Zn battery based on Ni3S2@SNCNT hollow fiber cathode manifests two-set charge discharge characteristics, high energy/power densities and good long-term durability. Additionally, the flexible HZB devices based on the Ni3S2@SNCNT flexible cathode achieve the high performance, unique self-breathing abilities and high adaptation in multfarious working conditions. More impressively, they exhibit good uninterrupted working ability even in the sudden transitions on working conditions. Therefore, this work not only provides a highly reliable, trifunctional and flexible electrode, but also promotes the development of the high-performance power sources for the electronics in multifarious conditions.

Automated summary

A hollow fiber electrode composed of S, N-doped carbon nanotubes confined nickel sulfide nanoparticles was designed for hybrid Zn batteries, exhibiting high electrocatalytic performance. The electrode provides fast electron/ion pathways, abundant active sites, and superior OER/ORR catalytic activities, promoting the development of high-performance power sources for electronics.