Protective catalytic layer powering activity and stability of electrocatalyst for high-energy lithium-sulfur pouch cell

Designing an electrocatalyst that simultaneously satisfies high catalytic activity and surface stability is essential for realizing high-performance lithium-sulfur (Li||S) batteries. Here, we propose an advanced electrocatalyst by constructing a thin protective catalytic layer (PCL) on the surface of metal nanoparticle catalysts. This few atomic layer thicknesses of the PCL composed of pyridinic N embedded graphitic carbon allows electrons to transfer from a metal nanoparticle to pyridinic N, resulting in an optimized p-orbital level of pyridinic N of PCL favorable for highly active conversion reaction of lithium sulfide. Further, PCL suppresses the direct contact of sulfur species with metal electrocatalysts. This surface protection effect inhibits the phase change of metal electrocatalysts to metal sulfide impurities, which maintains a highly active Li||S electrocatalysis for long-term cycling. Consequently, A h-level Li||S pouch cell with >500 W h kg−1 (specific energy based on current collector, anode, separator, electrolyte, and cathode), Coulombic efficiency (>95%), and stable life of 20 cycles was successfully realized. Design of electrocatalyst in lithium sulfur batteries is important to improve electrochemical performance. Here, authors use protective carbon layer to modulate the metal p-band center and prevent undesirable phase change of electrocatalyst for realizing 1 A h level lithium sulfur pouch cell.