Solid-State Battery Challenges for Industrial Solid Electrolytes

摘要

Solid State Batteries (SSB) become the main focus technology for academic as well as industrial research and development to overcome the limits of Lithium Ion Batteries in energy density and safety. Highly conductive, electrochemical stable solid electrolytes are essential to realize SSB cells. Two of the most promising materials the oxidic Li-ion conductors Li[7]La[2]Zr[3]0[12] (LLZO) and Li[2]0-Al[2]0[3]-TiO[2]-P[2]0[5] (LATP) are presented from an industrial point of view. While academic material research is often based on volumes <100g, the outlook for higher volumes is important for industry. The possibility is demonstrated, that scalable processes can be used to realise high performance LLZO and LATP. The cubic LLZO possesses a total ionic conductivity over 3x10 E 4 S/cm and stability against lithium metal. LATP is the material of interest for ionic conduction in cathodes. It has a total conductivity over 2×10 E-4 S/cm, which can be extended to over 5×10 E-4 S/cm even at low sintering temperatures. Both materials sufficiently prevent self-discharge of batteries as their electronic conductivity is 6 orders of magnitude lower than their ionic conductivity. Furthermore, their transference number of ~ 1 allows fast charging of batteries. The solid electrolytes are chemical stable in dry air and common battery electrolytes. One of the key challenges is the controlled processing of LLZO and LATP enabling low interfacial resistances against other solid-state battery components. Especially the performance of LLZO is highly depended on surface contamination. Pyrochlor and carbonate layers lead to very high interface resistances. Advanced processing is able to reduce these interface resistances by orders of magnitude. Another important challenge is the incorporation of these oxidic particles into the cell. Either sintering or incorporation of the particles into polymer-based matrixes are often used. The unique glass ceramic nature of the SCHOTT materials allows a further adaption to system and processing needs. Production of both LLZO and LATP seems feasible at industrial scale using SCHOTT melting and glass-ceramic technologies incl. modern recycling concepts. This offers the possibility towards commercialisation of Solid-State Batteries for EV applications.