Synergistic electronic-state modulation and structural design strategies of multichannel carbon skeleton for robust...

The escalating energy demands and environmental challenges have driven the development of sodium metal batteries (SMBs) as promising alternatives to lithium-ion batteries (LIBs). However, the practical application of SMBs is hindered by the uncontrolled Na dendrite growth and severe volume expansion during Na deposition process. Herein, a self-standing nitrogen-doped three-dimensional carbon skeleton composed of multi-channel carbon nanofibers (MCNFs) was constructed by a simple electrospinning route following by subsequent calcination to serve as a sodiophilic host for stable sodium metal deposition. The abundant nitrogen-doped sodiophilic sites of MCNFs reduce the nucleation barrier and induce dendrite-free Na deposition. Meanwhile, the conductive porous MCNFs skeleton not only shortens ions/electrons migration distances, but also reduces local current densities and provides enough Na metal storage space. The refined electronic-state modulation and unique structural design of the MCNFs skeleton synergistically suppress Na dendrite growth and alleviate volume change. As a freestanding Na deposition current collector, the Na//MCNFs asymmetric battery demonstrates superior cycling stability over 1300 cycles with an Average Coulombic efficiency (ACE) of 99.9 % at 1 mA cm^-2/0.5 mAh cm^-2. Especially, the Na@MCNFs//NVP full cell with a lean Na metal anode achieves exceptional cycling stability, retaining 79.8 % of initial capacity after 2700 cycles at 5C. This work provides vital guidance for constructing functional host by elaborate electronic-state modulation and unique structure design for dendrite-free metal-based batteries.