Manipulating Li <sub>2</sub> S Redox Kinetics and Lithium Dendrites by Core–Shell Catalysts under High Sulfur Loading and Lean‐Electrolyte Conditions
Mengmeng Zhen, Kaifeng Li, Mingyang Liu
Abstract
Abstract For practical lithium–sulfur batteries (LSBs), the high sulfur loading and lean‐electrolyte are necessary conditions to achieve the high energy density. However, such extreme conditions will cause serious battery performance fading, due to the uncontrolled deposition of Li 2 S and lithium dendrite growth. Herein, the tiny Co nanoparticles embedded N‐doped carbon@Co 9 S 8 core–shell material (CoNC@Co 9 S 8 NC) is designed to address these challenges. The Co 9 S 8 NC‐shell effectively captures lithium polysulfides (LiPSs) and electrolyte, and suppresses the lithium dendrite growth. The CoNC‐core not only improves electronic conductivity, but also promotes Li + diffusion as well as accelerates Li 2 S deposition/decomposition. Consequently, the cell with CoNC@Co 9 S 8 NC modified separator delivers a high specific capacity of 700 mAh g −1 with a low‐capacity decay rate of 0.035% per cycle at 1.0 C after 750 cycles under a sulfur loading of 3.2 mg cm −2 and a E / S ratio of 12 µL mg −1 , and a high initial areal capacity of 9.6 mAh cm −2 under a high sulfur loading of 8.8 mg cm −2 and a low E / S ratio of 4.5 µL mg −1 . Besides, the CoNC@Co 9 S 8 NC exhibits an ultralow overpotential fluctuation of 11 mV at a current density of 0.5 mA cm –2 after 1000 h during a continuous Li plating/striping process.