Densifying Solid Electrolytes through Surface Lubrication to Mitigate Shorting of Solid-State Batteries

Abstract

Lithium dendrite penetration has caused internal short-circuits that have limited the life of lithium metal all-solid-state batteries. Defects and pores in dry compacted solid electrolytes promote dendrite growth. This study introduces an organic molecular coating, 1-undecanethiol, that anchors strongly to the surface of Li₆PS₅Cl and functions as an adsorbed lubrication layer, thus reducing interparticle friction, facilitating particle rearrangement and densification. Under a compacting pressure of 375 MPa, the 1-undecanethiol coated Li₆PS₅Cl achieves a porosity of 1.7%, a substantial reduction from the porosity of 10.9% for Li₆PS₅Cl. As a result, Li symmetric cells incorporating the 1-undecanethiol densified Li₆PS₅Cl pellet exhibit up to a 4-fold increase in critical current density and demonstrate remarkable 4600 h cycling at a current density of 1 mA cm^–2. Likewise, the Li||LiNi_0.8Co_0.1Mn_0.1O₂ full cell shows a 4-fold increase in cycling current density. This work points to the potential of organic surface engineering to enable long-life solid-state batteries.