Garnet-Type Solid-State Electrolytes: Materials, Interfaces, and Batteries

Abstract

Solid-state batteries with desirable advantages, including high-energy density, wide temperature tolerance, and fewer safety-concerns, have been considered as a promising energy storage technology to replace organic liquid electrolyte-dominated Li-ion batteries. Solid-state electrolytes (SSEs) as the most critical component in solid-state batteries largely lead the future battery development. Among different types of solid-state electrolytes, garnet-type Li7La3Zr2O12 (LLZO) solid-state electrolytes have particularly high ionic conductivity (10–3 to 10–4 S/cm) and good chemical stability against Li metal, offering a great opportunity for solid-state Li-metal batteries. Since the discovery of garnet-type LLZO in 2007, there has been an increasing interest in the development of garnet-type solid-state electrolytes and all solid-state batteries. Garnet-type electrolyte has been considered one of the most promising and important solid-state electrolytes for batteries with potential benefits in energy density, electrochemical stability, high temperature stability, and safety. In this Review, we will survey recent development of garnet-type LLZO electrolytes with discussions of experimental studies and theoretical results in parallel, LLZO electrolyte synthesis strategies and modifications, stability of garnet solid electrolytes/electrodes, emerging nanostructure designs, degradation mechanisms and mitigations, and battery architectures and integrations. We will also provide a target-oriented research overview of garnet-type LLZO electrolyte and its application in various types of solid-state battery concepts (e.g., Li-ion, Li–S, and Li–air), and we will show opportunities and perspectives as guides for future development of solid electrolytes and solid-state batteries.

Sulfide and Oxide Inorganic Solid Electrolytes for All-Solid-State Li Batteries: A Review

“…Tatsumisago et al [24] and Sakuda et al [25] published important reviews on sulfide electrolytes, while Thangadurai et al [26,27] reviewed garnet electrolytes. Furthermore, the fundamentals of ASSBs were reviewed by several authors [28][29][30][31][32][33][34][35]. The number of reviews on various aspects of electrolytes, cathodes, mechanical properties, and interface engineering has grown exponentially since 2018 .…”

A Review of Functional Separators for Lithium Metal Battery Applications

“…To solve the challenge of interfacial resistance in SEs, Wang et al suggested a method of coating nanoscale and lithiophilic zinc oxide (ZnO) onto the surface of a garnet-type SE [ 153 ]. Generally, the garnet-type SE is widely used in SEs owing to its high energy density, electrochemical stability, high temperature stability, and safety [ 154 ]. Because of the ultrathin and conformal ZnO surface coating, molten Li reacts with ZnO and produces better contact with the surface of the garnet electrolyte by reducing the interfacial resistance ( Figure 14 a).…”

“…; ( b ) Ge-coated garnet electrolyte. Reprinted with permission from [ 154 ]. Copyright (2017) John Wiley and Sons.…”

A Self‐Healing Amalgam Interface in Metal Batteries

“…In contrast to Li-amalgam-LLTO cell, the pure Li-LLTO cell shows a poor contact between lithium metal and electrolyte even after cycling (Figure 3d,e). [40,41] XRD analysis reveals that Li-deficient alloy (LiHg 3 ) phase appearing in the interface can be transformed to Li-rich alloy (Li 3 Hg) phase ((JCPDF)-04-004-8747) after the first cycle (Figure 1l and Figure 3l), and SEM images show that the lithium amalgam interface between the metal anode and electrolyte undergoes a reversible phase transition from solid to liquid at room temperature during delithiation/lithiation cycling process (Figure 3g). Clearly, it can be observed that the liquid amalgam appears in the interface between lithium amalgam anode and electrolyte, when Liamalgam-LLTO cell is disassembled and broken down into two parts ( Figure S13, Supporting Information).…”