Excellent Cathode Interfaces Achieved by Atomic/Molecualr Layer Depositions for Sulfide-Based All-Solid-State Batteries

Abstract

All-solid-state Lithium batteries (ASSLBs) are attracting a large amount of attention due to the improved safety and high energy density compared with conventional liquid electrolyte-based Li-ion batteries (LIBs). Sulfide-based solid-state electrolytes (SSEs) exhibit ultrahigh ionic conductivity up to 10-2 S cm-1 at room temperature (RT). [1] However, the interface between sulfide SSEs and oxide cathode materials is considered unstable. The reason of the poor cathode interface stability is originated form the low oxidation potential of sulfide SSEs. This causes big chemical-potential gap between sulfides and oxide cathode materials, which would cause the formation of space-charge layer and increase the interfacial impedance. [1] Additionally, the low oxidation limit of sulfides leads to severe decomposition of SSEs at the cathode interface, thus affecting the interfacial Li+ transport. Designing coating materials for cathode particles is the most common strategy to alleviate the cathode interface problems. [2]Atomic/molecular layer deposition (ALD/MLD) is an advanced film fabricating technique, capable of tuning the interface property with atomic-level thickness control at relatively low temperature (< 400 oC). Compared with the conventional wet chemical method (e.g., sol-gel method), the ALD/MLD method can not only show the ability of developing Li-containing ternary oxides and organic coatings with uniform and conformal features, but also completely avoid the negative effects of using solvents and high-temperature treatments. [2-4] In our work, we employed ALD/MLD to elaborately design LiNbOx, LiZrOx, LiPOx, and PEDOT coating materials to solve the interface problem between sulfide SSEs and oxide cathode materials. [5-8] Ion-conducting and electron-insulating ALD coating layers can prevent the interfacial side reactions and improve the Li+ transport, while the semiconductor MLD layer can suppress the interfacial degradation. Therefore, excellent performance of sulfide-based ASSLBs was obtained. Ex/in-situ synchrotron X-ray characterizations (XANES, EXAFS, STXM) were used to analyze the local structure of ALD/MLD coatings and reveal the working mechanism of designed interfaces. The flexible design of functional cathode interface realized by ALD/MLD coatings paves the way to achieve advanced sulfide-based ASSLBs. Re ferences C. Yu, F. Zhao, X. Sun*, et al. Recent Development of lithium argyrodite solid-state electrolytes for solid-state batteries: synthesis, structure, stability and dynamics. Nano Energy 2021, 83, 105858.Y. Zhao, F. Zhao, X. Sun*, et al. Atomic/molecular layer deposition for energy storage and conversion. Chem. Soc. Rev., 2021, 50, 3889-3956.Y. Zhao, X. Sun*, et al. Addressing interfacial issues in liquid-based and solid-state batteries by atomic and molecular layer deposition, Joule 2018, 2, 2583-2604.Y. Zhao, X. Sun*. Molecular Layer Deposition for Energy Conversion and Storage, ACS Energy Lett. 2018, 3, 899-914.F. Zhao, X. Sun*, et al. Tuning bifunctional interface for advanced sulfide-based all-solid-state batteries. Energy Storage Mater. 2020, 33, 139-146.C. Wang, F. Zhao, X. Sun* et al. Manipulating Interfacial Nanostructure to Achieve High-Performance All-Solid-State Lithium-Ion Batteries, Small M e thods, 2019, 3, 1900261.S. Deng, X. Sun*, et al. Dual-functional interfaces for highly stable Ni-rich layered cathodes in sulfide all-solid-state batteries Energy Storage Mater. 2020, 27, 117-123.S. Deng, X. Sun*, et al. Eliminating the Detrimental Effects of Conductive Agents in Sulfide-Based Solid-State Batteries, ACS Energy Lett. 2020, 5, 1243-1251.