Lignin-derived carbon framework is developed for reversible sodium deposition. This framework boosts an expansive specific surface area and a wealth of oxygen-rich functional groups, which serve to cushion the volume fluctuations of sodium metal throughout the electrochemical cycle, directing the even deposition of sodium ions.

Abstract

Sodium metal batteries have become popular owing to their low redox potential, high theoretical capacity, and superior energy density. But the formation of sodium dendrites during electrochemical cycles diminishes the security and longevity of these batteries. In response to this challenge, we employ lignin as a carbon source to fabricate a three-dimensional (3D) carbon framework current collector. This framework boosts an expansive specific surface area and a wealth of oxygen-rich functional groups. These components serve to cushion the volume fluctuations of sodium metal throughout the electrochemical cycle, directing the even deposition of sodium ions. The as-prepared anode displays a low overpotential of −7 mV and a stable cycling life of 400 hours at 0.5 mA cm⁻². When coupled with Na₃V₂(PO₄)₃ cathode, the full cell can achieve a capacity of 97.6 mAh g⁻¹ and a capacity retention of 94.7 % after 60 cycles. This research shows that using lignin as a carbon source to prepare a 3D carbon framework current collector is an effective mean to inhibit the harmful effects of sodium dendrites on batteries.