Non-trivial Contribution of Carbon Hybridization in Carbon-based Substrates to Electrocatalytic Activities in Li-S Batteries

Appling an electrochemical catalyst is an efficient strategy for inhibiting the shuttle effect and enhancing the S utilization of Li-S batteries. Carbon-based materials are the most common conductive agents and catalyst supports used in Li-S batteries, but the correlation between the diversity of hybridizations and sulfur reduction reaction (SRR) catalytic activity remains unclear. Here, by establishing two forms of carbon models, i.e., graphitic carbon (GC) and amorphous carbon (AC), we observe that the nitrogen atom doped in the GC possesses a higher local charge density and a lower Gibbs free energy towards the formation of polysulfides than in the AC. And the GC-based electrode consistently inherits considerably enhanced SRR kinetics and superior cycling stability and rate capability in Li-S batteries. Therefore, the function of carbon in Li-S batteries is not only limited as conductive support but also plays an unignorable contribution to the electrocatalytic activities of SRR.

Automated summary

Applying electrochemical catalysts is an effective strategy to improve the utilization of sulfur in Li-S batteries by inhibiting the shuttle effect. Carbon-based materials, commonly used as conductive agents and catalyst supports, show varying catalytic activity for sulfur reduction reaction (SRR) due to different hybridizations. By comparing graphitic carbon (GC) and amorphous carbon (AC), it is found that nitrogen-doped GC exhibits higher local charge density and lower Gibbs free energy for polysulfides formation. The GC-based electrodes consistently demonstrate enhanced SRR kinetics, superior cycling stability, and rate capability in Li-S batteries, indicating that carbon plays an important role not only as a conductive support but also as an electrocatalyst for SRR.