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

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 Li 6 PS 5 Cl 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 Li 6 PS 5 Cl achieves a porosity of 1.7%, a substantial reduction from the porosity of 10.9% for Li 6 PS 5 Cl. As a result, Li symmetric cells incorporating the 1-undecanethiol densified Li 6 PS 5 Cl 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 0.8 Co 0.1 Mn 0.1 O 2 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.