Origin of High Interfacial Resistance in Solid‐State Batteries: LLTO/LCO Half‐Cells**

Abstract

The interface between cathode and electrolyte is a significant source of large interfacial resistance in solid-state batteries (SSBs). Spark plasma sintering (SPS) allows densifying electrolyte and electrodes in one step, which can improve the interfacial contact in SSBs and significantly shorten the processing time. In this work, we proposed a two-step joining process to prepare cathode (LiCoO 2 , LCO)/electrolyte (Li 0.33 La 0.57 TiO 3 , LLTO) half cells via SPS. Interdiffusion between Ti 4 + / Co 3 + was observed at the interface by SEM/STEM, resulting in the formation of the LiÀ TiÀ LaÀ CoÀ O and LiÀ TiÀ CoÀ O phases in LLTO and the LiÀ CoÀ TiÀ O phase in LCO. Computational modeling was performed to verify that the LiÀ TiÀ CoÀ O phase has a LiTi 2 O 4 host lattice. In a study of interfacial electrical properties, the resistance of this interdiffusion layer was found to be 10 5 Ω, which is 40 times higher than the resistance of the individual LLTO phase. The formation of an interdiffusion layer is identified as the origin of the high interface resistance in the LLTO/LCO half-cell.

Dilithium phthalocyanine - A Single Ion Transport Interfacial layer for Solid-State Lithium Batteries

“…The uneven solid-solid interfaces limit ion migration and enhance the Li-dendrite formation on anodes. [1][2][3] The interfacial issues influence and limit the overall performance of the solid-state Liion battery. A space charge layer (SLC) is formed at the interface by the redistribution of mobile carriers upon contact of two phases with different chemical potentials.…”