In a solid-state battery, the liquid electrolyte is replaced by a solid material known as a solid electrolyte that also helps the lithium ions move quickly. One technical challenge is that while the lithium ions can move quickly within the solid electrolyte, they have a hard time moving from the solid electrolyte to the electrodes and vice versa. The solid electrolyte can be compared to a cadre of trains, also quickly shuttling the lithium ions to the station, but then the passengers still have to travel a bit farther to get home. One way that scientists have managed to speed up this ‘direct shuttling’ – and thus battery charging speeds and performance – is by adding a little bit of liquid electrolyte to the positive side of the battery.
