Facilitating polysulfide confinement using N-doped honeycomb-like carbon with high pyridinic-nitrogen content for high-performance Li-S batteries

Increasing the amount of the nitrogen dopant, especially pyridinic-N species, in carbonaceous materials has been shown to significantly enhance the performance of lithium-sulfur (Li-S) batteries. Despite the positive impact of N doping on carbonaceous materials, the practical realisation of a high N dopant content of >5 at.% remains a significant challenge. Furthermore, to regulate the specific N species in carbonaceous materials is another hurdle. Herein, we obtained a three-dimensional honeycomb-like N-doped mesoporous carbon (PNMC) material with a high N dopant content of 8.82 at.% (pyridinic-N content, 3.49 at.%) by calcining calcium pantothenate under an Ar atmosphere after a phosphorisation process. It is believed that the P dopant contributes to the enhancement of not only the N content but also the polysulfide adsorption capability of the N dopant. As expected, the sulfur cathode comprising PNMC prepared at 800°C (S/PNMC-800) exhibited superior electrochemical performance as confirmed by the discharge specific capacity of 556.7 mA h g⁻¹ observed after 300 cycles at 1 C. This study proposes a facile regulation technique to dope pyridinic-N species in carbonaceous materials, which may trigger the future inventive development of functional S hosts for use in Li-S batteries. [Figure not available: see fulltext.]