Nitrogen-doped carbon supported cobalt single-atom catalysts for enhanced Cl2 adsorption and conversion in sodium-chlorine batteries

The development of sodium-chlorine (Na-Cl 2 ) secondary batteries is constrained by several key challenges, including poor cycling stability, sluggish Cl 2 redox kinetics, and insufficient electrical conductivity. In this work, we design and employ a cobalt single-atom catalyst supported on nitrogen-doped carbon (Co-NC) to mitigate these limitations. The nitrogen-doped carbon framework carbonized at 900 ℃ (NC-900) possesses a high specific surface area and an appropriate defect density, which facilitates the atomic dispersion of Co sites. The Co-NC catalyst markedly strengthens Cl 2 adsorption, reduces the energy barrier for the NaCl/Cl 2 conversion reaction, and enhances Na + transport across the electrode/electrolyte interface. Consequently, a Na-Cl 2 battery employing a 15 wt% Co-NC cathode achieves an ultrahigh initial discharge capacity of 6255.4 mAh·g -1 and retains over 95% energy efficiency after 140 cycles at room temperature. Furthermore, the Co-NC-based cell exhibits outstanding low-temperature performance, operating effectively at 0 ℃. This work offers a rationally guided catalyst design strategy for advancing high-performance chlorine-based rechargeable batteries. • Co single-atom catalyst anchored on N-doped carbon enhances Cl₂ adsorption and conversion. • Na-Cl 2 battery with Co-NC cathode delivers 6255.4 mAh·g⁻¹ initial discharge capacity. • Over 95% energy efficiency retained after 140 cycles at room temperature. • Superior low-temperature performance demonstrated at 0℃ with stable cycling.