(Invited) Laser Processing of Solid-state Electrolytes for All-Solid-state Lithium Batteries

Abstract

Solid-state electrolytes (SSEs) with high ionic conductivity, wide electrochemical stability window and operating temperature window, are promising to replace flammable organic liquid electrolytes for high energy/power density and safe battery systems. However, the processing of SSE components in all-solid-state lithium batteries (ASSLBs) is challenging due to the intrinsic brittleness, air sensitivity, high sintering temperature (for garnet-type SSEs), and poor solid-solid contact. Here, using garnet-type SSEs as a model system, we report rapid laser processing to tackle these processing challenges. First, rapid laser sintering can be used to densify porous LLZO green body with minimal Li loss. Reactive laser sintering can be used to synthesize pure LLZO phase from precursor mixtures. Local laser heating is capable of generating dense/porous bilayers or gradient porous structures. It provides versatile tunability to generate various grain structures to be linked with ion transport properties. Second, laser heating or pulse laser ablation can be used to treat the surface to remove contaminates (Li2CO3, etc.) or generate 3D interfaces that helps to reduce interfacial resistance. Finally, ultrafast laser sintering is beneficial for co-sintering of cathode/SSE to facilitate solid-solid contact while minimizing side reactions. With direct laser energy absorption, extremely fast heating and cooling rates, highly tunable laser parameters, promising scalability, and great integrability, laser-based processing could be an ideal manufacturing approach for ASSLBs. Despite the above benefits, challenges such as temperature gradient induced crack formation will also be discussed in this presentation.