Binder-free sheet-type all-solid-state batteries with enhanced rate capabilities and high energy densities

All-solid-state batteries using inorganic solid electrolytes are considered promising energy storage systems because of their safety and long life. Stackable and compact sheet-type all-solid-state batteries are urgently needed for industrial applications such as smart grids and electric vehicles. A binder is usually indispensable to the construction of sheet-type batteries; however, it can decrease the power and cycle performance of the battery. Here we report the first fabrication of a binder-free sheet-type battery. The key to this development is the use of volatile poly(propylene carbonate)-based binders; used to fabricate electrodes, solid electrolyte sheets, and a stacked three-layered sheet, these binders can also be removed by heat treatment. Binder removal leads to enhanced rate capability, excellent cycle stability, and a 2.6-fold increase in the cell-based-energy-density over previously reported sheet-type batteries. This achievement is the first step towards realizing sheet-type batteries with high energy and power density.