A Nickel-Decorated Carbon Flower/Sulfur Cathode for Lean-Electrolyte Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries involve a reversible conversion reaction between sulfur and lithium sulfide (Li2S) via a series of soluble lithium polysulfide intermediates (LiPSs), enabling a high theoretical specific capacity of 1675 mAh g(-1). However, this process exhibits large polarization and low sulfur utilization and suffers critical capacity fade. The primary approach to tackle the problem has so far been to infiltrate sulfur into nanostructured carbon. However, most studies using porous carbon as host materials have tested with high electrolyte to sulfur ratios (E/S) (generally > 15 mu L mg(-1)) that compromise the cell-level energy density. Here, a flower-shaped porous carbon structure with nickel nanoparticles that can address the problems discussed above is designed. First, the 3D flower-shaped carbon structure enables short ionic transport lengths. Second, the small pore diameters 3300 m(2) g(-1) with sufficient pore volume are ideal for charging performance for low E/S ratios. Finally, Ni nanoparticles are employed onto the flower-shaped network to improve the reaction kinetics. Collectively, it is successfully demonstrated that the batteries with a high mass loading of 5 mg cm(-2) and a 5 mu L mg(-1) E/S ratio can retain cycle retention of 70% after 150 cycles.

Automated summary

By designing a flower-shaped porous carbon structure with nickel nanoparticles, the issues of large polarization, low sulfur utilization, and capacity fade in lithium-sulfur batteries have been addressed. The 3D flower-shaped carbon structure enables short ionic transport lengths, while the small pore diameters and sufficient pore volume are ideal for improving charging performance at low electrolyte to sulfur ratios. The use of Ni nanoparticles on the flower-shaped network improves reaction kinetics, leading to successful demonstration of batteries with high mass loading and good cycle retention.