Optimized lithium deposition on Ag nanoparticles-embedded TiO₂ microspheres: a facile spray pyrolysis approach for enhanced lithium metal anode

The lithium anode is considered the “holy grail” anode for replacing conventional graphite-based anodes because of its high theoretical capacity and lowest redox potential; however, safety problems arising from the dendritic growth of lithium and large volume fluctuation require resolution to make its commercialization viable. The introduction of a 3D matrix with lithiophilic materials can effectively overcome the challenges that lithium metal batteries associate with commercialization. In this study, we fabricated composite microspheres using TiO₂ as an electrochemically stable 3D scaffold and well-dispersed Ag nanoparticles as lithiophilic sites (defined as 600-TiO₂-5Ag) via facile spray pyrolysis. Uniquely structured 3D host materials for lithium metal anodes (LMAs) consistently demonstrated stable lithium deposition and stripping performance over 500 cycles while being tested under a current density of 1.0 mA cm^-2 in an asymmetrical cell. In addition, we studied their lithium storage mechanisms through FIB-TEM analysis. Furthermore, with the deposition of 5.0 mA h cm^-2 of lithium, the symmetric cell exhibited a low overpotential of 24 mV for over 1000 h, and a full cell assembled with commercial LiNi_0.8Co_0.1Mn_0.1O₂ (NCM 811) also displayed highly enhanced cell stability and rate capability. This work suggests combining intercalation- and alloying-type materials to synergistically enhance the lithium deposition behavior of LMAs.