Despite the promising prerequisites of LLZO its integration into a battery is associated with the formation of complex solid-to-solid interfaces that arise as the main bottlenecks to achieve high power density, rate capacity, and capacity retention of SSBs, which impede their ultimate commercial usage. Whereas for the Li | LLZO interface significant improvements have been achieved, the cathode side still suffers from technical challenges such as poor contact between the LLZO and the cathode or contact loss during cycling due to volume changes within the cathode. A stable interface contact is a key requirement for high initial discharge capacities, this however, requires high temperature processing. To form sufficient bonding between the individual components in an all-oxide cathode composed by LLZO and LiCoO2 (LCO) temperatures from 600 to 1050 °C are required (see Table ).