Solid electrolytes and solid state batteries are currently attracting serious interest as potential future components and storage devices. Solid electrolytes (polymer, ceramic or composites) are required to construct protected lithium anodes – in case that lithium metal anodes will become again part of lithium batteries. If the cathode is still employed in contact with a liquid electrolyte, a new interface between a liquid and a solid electrolyte forms which can be highly resistive. Solid state batteries without any liquid electrolytes are considered as ultimately stable and safe devices, but are expected to suffer from poor kinetics and high costs. The lecture will include answers to the following questions:

• Are solid electrolytes necessarily worse lithium ion conductors than liquid electrolytes?

• Are solid electrolytes necessarily more stable than liquid electrolytes?

• What do we know about the interface between liquid and solid electrolytes?

• Status quo of thin and thick film solid state batteries?

• Important research tasks in the development of solid state batteries?