All-Solid-State Batteries Containing Lithium Thiophosphate Separators

E.C. Self, F.M. Delnick, G. Yang, T. Brahmbhatt, W-Y Tsai, J. Nanda
Oak Ridge National Laboratory,
United States

Keywords: solid-state batteries, sulfide solid electrolytes, Li metal anodes


All-Solid-State Batteries Containing Lithium Thiophosphate Separators Ethan C. Self[a], Frank M. Delnick[a], Guang Yang[a], Teerth Brahmbhatt[b], Wan-Yu Tsai[a], and Jagjit Nanda[a] [a] Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA [b] The Bredesen Center for Interdisciplinary Research and Graduate Education, The University of Tennessee, Knoxville, TN, 37996, USA Active material selection largely dictates the performance of Li-ion batteries, and replacing the graphite anode with Li metal can enable batteries with specific energies >400 Wh/kg (compared to ~250 Wh/kg for today’s state-of-the-art Li-ion systems). Li metal batteries containing conventional liquid electrolytes (e.g., LiPF6 in organic carbonates) have been unable to suppress Li dendrite formation during charging which presents major safety concerns. To stabilize Li plating/stripping, there is growing interest solid-state batteries (SSBs) containing solid electrolyte (SE) separators. Representative classes of solid-state Li+ conductors include oxides, sulfides, polymers, and phosphorus oxynitride glasses. Among these, sulfide materials offer several key advantages including: (i) high Li+ conductivity comparable to that of liquid electrolytes (ca. 1-10 mS/cm at room temperature) and (ii) soft mechanical properties which facilitates preparing dense separators. However, integrating sulfide SEs with Li metal anodes and high voltage cathodes remains challenging due to the SE’s narrow electrochemical stability window. This presentation will provide a systematic overview of how approaches commonly reported in the literature impact the cycling performance of SSBs containing sulfide SE separators. More specifically, we will discuss how different active materials, carbon additives, and interface coating strategies impact reversible capacity and cycling stability. Effects of stack pressure and anode compositions (e.g., Li metal vs. LixIn alloys) will also be highlighted. Overall these results demonstrate that, while opportunities for Li metal batteries are tremendous, enabling practical, high energy SSBs requires overcoming major challenges related to material processing, cathode design, and interfacial stabilization. Acknowledgements This research was conducted at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE) and is sponsored by the Office of Energy Efficiency and Renewable Energy (EERE) through the Vehicle Technologies Office (VTO).