High-Performance Sulfide-based Solid-state Electrolytes and Interfaces for All-solid-state Li Batteries

Abstract

All-solid-state Lithium metal batteries (ASSLMBs) cannot only maximize the energy density, but also show improved safety compared with the conventional liquid electrolyte-based Li-ion batteries. Solid-state electrolytes (SSEs), as the most important component in the ASSLMBs, can determine the electrochemical performance. High ionic conductivity is one of the most basic requirements for an excellent SSE. Sulfide-based SSEs exhibit ultrahigh ionic conductivity (> 10-2 S cm-1 at room temperature) that can be comparable to the liquid electrolytes, making this kind of SSEs popular and promising.1 However, air sensitivity and Li metal incompatibility are two major obstacles, which are together with the problematic cathode interface, hindering the development of sulfide SSEs for practical ASSLMBs.2, 3 In our work, we employed the strategy of element substitution to design F-substituted Li6PS5Cl, Sn-substituted Li6PS5I, and Sn-substituted Li3PS4 as high-performance Li-metal compatible sulfide SSEs.4-6 Using these element doping SSEs can derive functional interphases that contain LiF, LiI, and Li-Sn alloy, respectively. These interfacial contents were demonstrated as important to achieve stable Li plating/stripping. Importantly, we found that replacing P with Sn could significantly improve the air stability and ionic conductivity at the same time. The high reaction energy between the Sn-substituted PS4 tetrahedra and moisture was regarded as the main reason for the improved air stability, while the expanded unit cell and increased Li+ concentration led to superior ionic conductivity. Our modifications on various common-used sulfide SSEs with multi-function elements provide more choices of sulfide SSEs for practical ASSLMBs. At the cathode side,7-10 we used interface modification (coating strategy) to improve the interfacial Li+ transport and chemical inertness. Thus, excellent electrochemical performance was achieved. Re ferences N. Kamaya, R. Kanno*, et al. A lithium superionic conductor, Nat. Mater. 2011, 10, 682-686.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.F. Zhao, X. Sun*, et al. Ultrastable anode interface achieved by fluorinating electrolytes for all-solid-state Li metal batteries, ACS Energy Lett. 2020, 5, 1035-1043F. Zhao, X. Sun*, et al. A Versatile Sn-Substituted Argyrodite Sulfide Electrolyte for All-Solid-State Li Metal Batteries, Adv. Energy Mater. 2020, 10, 1903422.F. Zhao, X. Sun*, et al. An Air-Stable and Li-Metal-Compatible Glass-Ceramic Electrolyte enabling High-Performance All-Solid-State Li-Metal Batteries. Adv. Mater. 2021, 33, 2006577.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 Methods, 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.