Lithium garnet-cathode interfacial chemistry: inclusive insights and outlook toward practical solid-state lithium metal batteries

Solid-state lithium batteries have attained tremendous interest over the past few years as a possible alternative to the present lithium-ion battery because of their improved safety and higher energy density. The key component of a solid-state battery is the solid electrolyte. Among various inorganic solid electrolytes ranging from sulfides to oxides, garnet structured oxide solid electrolytes emerged as a promising candidate due to their high lithium-ion conductivity as well as excellent stability with lithium metal and potential electrodes. However, garnet solid electrolyte-based solid-state battery's practical realization is limited by various challenges at the electrode-garnet interface, particularly the significant interface resistance and poor critical current density. Although significant developments have been made toward accomplishing an effective anode-garnet interface, the cathode-garnet interface is still challenging, and in-depth analysis with more emphasis on cathode-garnet interfacial chemistry is lacking. From this point of view, this review discusses the fundamentals of the cathode-garnet interface in detail and carefully summarizes the issues with various cathode materials and possible strategies to overcome them for the realization of 'anode free' high energy density lithium metal batteries. (C) 2021 Elsevier Ltd. All rights reserved.