A Low Temperature Soldered All Ceramic Lithium Battery

Solid Interfaces for the Garnet Electrolytes

Solid-state electrolytes (SSEs) have attracted extensive interests due to the advantages in developing secondary batteries with high energy density and outstanding safety. Possessing high ionic conductivity and the lowest reduction potential among the state-of-the-art SSEs, the garnet type SSE is one of the most promising candidates to achieve high performance solid-state lithium batteries (SSLBs). However, the elastic modulus of the garnet electrolyte leads to deteriorated interfacial contacts, and the increasing in electronic conduction at either anode/garnet interface or grain boundary results in Li dendrite growth. Here, recent developments of the solid interfaces for the garnet electrolytes, including the strategies of Li dendrite suppression and interfacial chemical/electrochemical/mechanical stabilizations are presented. A new viewpoint of the double edges of interfacial lithiophobicity is proposed, and the rational design of the interphases, as well as effective stacking methods of the garnet-based SSLBs are summarized. Moreover, practical roles of the garnet electrolyte in SSLB industry are also discussed. This work delivers insights into the solid interfaces for the garnet electrolytes, which provides not only the promotion of the garnet-based SSLBs, but also a comprehensive understanding of the interfacial stabilization for the whole SSE family.

Flexible Composite Electrolyte Membranes with Fast Ion Transport Channels for Solid-State Lithium Batteries

Numerous endeavors have been dedicated to the development of composite polymer electrolyte (CPE) membranes for all-solid-state batteries (SSBs). However, insufficient ionic conductivity and mechanical properties still pose great challenges in practical applications. In this study, a flexible composite electrolyte membrane (FCPE) with fast ion transport channels was prepared using a phase conversion process combined with in situ polymerization. The polyvinylidene fluoride-hexafluoro propylene (PVDF-HFP) polymer matrix incorporated with lithium lanthanum zirconate (LLZTO) formed a 3D net-like structure, and the in situ polymerized polyvinyl ethylene carbonate (PVEC) enhanced the interface connection. This 3D network, with multiple rapid pathways for Li+ that effectively control Li+ flux, led to uniform lithium deposition. Moreover, the symmetrical lithium cells that used FCPE exhibited high stability after 1200 h of cycling at 0.1 mA cm-2. Specifically, all-solid-state lithium batteries coupled with LiFePO4 cathodes can stably cycle for over 100 cycles at room temperature with high Coulombic efficiencies. Furthermore, after 100 cycles, the infrared spectrum shows that the structure of FCPE remains stable. This work demonstrates a novel insight for designing a flexible composite electrolyte for highly safe SSBs.

Fundamentals of the Cathode-Electrolyte Interface in All-solid-state Lithium Batteries

All-solid-state lithium batteries (ASSBs) enabled by solid-state electrolytes (SEs) including oxide-based and sulfide-based electrolytes have gained worldwide attention because of their intrinsic safety and higher energy density over conventional lithium-ion batteries (LIBs). However, despite the high ionic conductivity of advanced SEs, ASSBs still exhibit high overall internal resistance, the most significant contributor of which can be ascribed to the cathode-SE interfaces. This review seeks to clarify the critical issues regarding the cathode-SE interfaces, including fundamental principles and corresponding solutions. First, major issues concerning electro-chemo-mechanical instability between cathodes and SEs and their formation mechanisms are discussed. Then, specific problems in oxides and sulfides and various solutions and strategies toward interfacial modifications are highlighted. Efforts toward the characterization and analysis of cathode-SE interfaces with advanced techniques are also summarized. Finally, perspectives are offered on several problems demanding urgent solutions and the future development of SE applications and ASSBs.

Enhanced Moisture Stability of Lithium-Rich Antiperovskites for Sustainable All-Solid-State Lithium Batteries

Lithium-rich antiperovskites (LiRAPs) solid electrolytes have attracted extensive interest due to their advantages of structural tunability, mechanical flexibility, and low cost. However, LiRAPs are instinctively hygroscopic and suffer from decomposition in air, which not only diversifies their electrochemical performances in present reports but also hinders their application in all-solid-state lithium batteries (ASSLBs). Herein, the origin of the hygroscopicity, and also the effect of the hygroscopicity on the electrochemical performances of Li_3-x (OH_x )Cl are systematically investigated. Li_3-x (OH_x )Cl is demonstrated to be unstable in the air and prone to decompose into LiOH and LiCl. Nevertheless, with fluorine doping on chlorine sites, the hygroscopicity of LiRAPs is suppressed by weakening the intermolecular hydrogen bond between LiRAPs and H₂ O, forming a moisture-resistive Li_3-x (OH_x )Cl_0.9 F_0.1 . Taking advantage of its low melting point (274 °C), two prototypes of ASSLBs are assembled in the ambient air by means of co-coating sintering and melt-infiltration. With LiRAPs as the solder, low-temperature sintering of the ASSLBs with low interfacial resistance is demonstrated as feasible. The understanding of the hygroscopic behavior of LiRAPs and the integration of the moisture-resistive LiRAPs with ASSLBs provide an effective way toward the fabrication of the ASSLBs.