Anode-free sodium metal batteries (AFSMBs) are promising next-generation energy storage systems due to their high energy density and low cost. Unlike traditional designs that include a hard carbon or pre-deposited sodium metal anode, AFSMBs eliminate the anode material completely, with sodium metal forming in situ during the first charge as sodium ions deposit onto the current collector. While this design reduces weight and simplifies the structure, it also introduces new challenges. Sodium tends to deposit unevenly, forming harmful dendrites, and the interfacial layer on its surface, known as the solid electrolyte interphase (SEI), is often unstable. These issues shorten battery life and raise safety concerns.
In this work, the researchers developed a novel three-dimensional carbon nanofiber current collector and tackled these challenges by modifying its electronic structure through the introduction of Zn–N_x active sites. This structural tuning facilitates lateral sodium-ion diffusion and promotes flat, uniform sodium deposition during cycling, even at ultra-high capacities of 10 mAh cm⁻². More importantly, the Zn–N_x configuration enhances interactions with electrolyte components and facilitates the formation of a stable, inorganic-rich solid electrolyte interphase, thereby significantly improving the cycling stability of anode-free sodium metal batteries.
This study develops a novel current collector that enables the practical realization of stable, high-energy anode-free sodium metal batteries, and further highlights the crucial role of interfacial electronic structure in directing sodium behavior and improving interfacial stability at the nanoscale. The work titled “Electronic Structure Regulation Inducing Robust Solid Electrolyte Interphase for Stable Anode-free Sodium Metal Batteries” was published on Advanced Powder Materials (available online on 19 May, 2025).
DOI：https://doi.org/10.1016/j.apmate.2025.100303