Staged dendrite suppression for high safe and stable lithium-sulfur batteries

Abstract

The unavoidable dendrite growth and shuttle effect have long been stranglehold challenges limiting the safety and practicality of lithium-sulfur batteries. Herein, we propose a dual-action strategy to address the lithium dendrite issue in stages by constructing a multifunctional surface-negatively-charged nanodiamond layer with high ductility and robust puncture resistance on polypropylene (PP) separator. The uniformly loaded compact negative layer can not only significantly enhance electron transmission efficiency and promote uniform lithium deposition, but also reduce the formation of dendrite during early deposition stage. Most importantly, under the strong puncture stress encountered during the deterioration of lithium dendrite growth under limiting current, the high ductility and robust puncture resistance (145.88 MPa) of as-obtained nanodiamond layer can effectively prevent short circuits caused by unavoidable lithium dendrite. The Li||Li symmetrical cells assembled with nanodiamond layer modified PP demonstrated a stable cycle of over 1000 h at 2 mA cm⁻² with a polarization voltage of only 29.3 mV. Additionally, the negative charged layer serves as a physical barrier blocking lithium polysulfide ions, effectively mitigating capacity attenuation. The improved cells achieved a capacity decay of only 0.042% per cycle after 700 cycles at 3 C, demonstrating effective suppression of dendrite growth and capacity attenuation, showing promising prospect.