Solid-state batteries

Manufacturing of composite electrodes

Dry processing of composite cathodes.
© Fraunhofer IFAM

Dry processing of composite cathodes.

A main motivation for the development of solid-state batteries, besides the increased energy content, is their intrinsic safety as these contain, in contrast to conventional lithium-ion batteries, no flammable liquid electrolyte. Solid-state electrolytes further possess a high level of electrochemical stability and can thus enable the use of novel high voltage electrodes with a high cycle stability. According to theoretical calculations, specific energies above 400Wh/kg and energy densities of more than 1200 Wh/L are possible.

The scalability and processing of solid-state batteries represents a particular challenge. Hybrid electrolytes made of inorganic materials and polymers offer a material option with a high potential. Hereby, the complex structure of these electrolytes as well as the electrical and the ionic conductivity must be ensured.

One of our focus points is the manufacture of composite cathodes consisting of active material and a solid-state electrolyte, e.g. via inert processing through extrusion. The development and understanding of the individual process steps are hereby particularly in focus.

Thin-film batteries

Flexible thin-film electrode, e.g. for solid-state batteries.
© Fraunhofer IFAM

Flexible thin-film electrode, e.g. for solid-state batteries.

The low ionic conductivities of potential solid-state electrolytes can also be compensated for through the minimization of the electrolyte film thickness. The so-called thin-film technology also enables flexible as well as three-dimensional battery geometries. These are particularly of interest for miniaturized applications, but also for component integration as well as for self-sufficient sensor nodes.

During the manufacture of thin-film electrodes and batteries, the so-called PVD technology (physical vapor deposition) comes into play. Hereby, very thin layers are achieved with good phase boundaries for an optimal ionic conductivity.