Scientists have improved solid-state batteries by introducing an interlayer — made of a spreadable, “butter-like” material — that helps improve the current density tenfold, while also increasing performance and safety. The interlayer makes the battery cell significantly more stable and therefore able to withstand much higher current density. The soft mass is easy to apply onto the lithium metal anode in the battery.
Solid-state batteries could revolutionize electric transport. Unlike today’s lithium-ion batteries, solid-state batteries have a solid electrolyte and contain no environmentally harmful or flammable liquids. A solid-state battery can be compared to a dry sandwich: A layer of the metal lithium acts as a slice of bread and a ceramic substance is laid on top like a filling. This hard substance is the solid electrolyte of the battery, which transports lithium ions between the electrodes of the battery. But the sandwich is so dry, it is difficult to keep it together and there are also problems caused by the compatibility between the bread and the filling.
The material is made of nanoparticles of the ceramic electrolyte LAGP, mixed with an ionic liquid. The liquid encapsulates the LAGP particles and makes the interlayer soft and protective. The material, which has a similar texture to cold butter, fills several functions and can be spread easily.
Although the potential of solid-state batteries is well known, there is as yet no established way of making them sufficiently stable, especially at high current densities when a lot of energy is extracted from a battery cell very quickly such as at fast charge or discharge.
The new technology could lead to manufacture of large-scale, cost-effective, safe, and environmentally friendly batteries that deliver high capacity and can be charged and discharged at a high rate.