posted on 2021-10-05, 00:04authored byJean Philippe Beaupain, Katja Waetzig, Svenja-Katharina Otto, Anja Henss, Jürgen Janek, Michael Malaki, Anuj Pokle, Julian Müller, Benjamin Butz, Kerstin Volz, Mihails Kusnezoff, Alexander Michaelis
All
solid-state batteries
offer the possibility of increased safety
at potentially higher energy densities compared to conventional lithium-ion
batteries. In an all-ceramic oxide battery, the composite cathode
consists of at least one ion-conducting solid electrolyte and an active
material, which are typically densified by sintering. In this study,
the reaction of the solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 (LATP) and the active
material LiNi0.6Co0.2Mn0.2O2 (NCM622) is investigated by cosintering at temperatures between
550 and 650 °C. The characterization of the composites and the
reaction layer is performed by optical dilatometry, X-ray diffractometry,
field emission scanning electron microscopy with energy dispersive
X-ray spectroscopy, time-of-flight secondary ion mass spectrometry,
as well as scanning transmission electron microscopy (STEM). Even
at low sintering temperatures, elemental diffusion occurs between
the two phases, which leads to the formation of secondary phases and
decomposition reactions of the active material and the solid electrolyte.
As a result, the densification of the composite is prevented and ion-conducting
paths between individual particles cannot be formed. Based on the
experimental results, a mechanism of the reactions in cosintered LATP
and NCM622 oxide composite cathodes is suggested.