Garnet-Based Electrolytes for All-Solid-State Li-S Batteries

Lithium sulfur (Li-S) batteries have emerged as one of the most promising post LIBs technologies with a remarkably high theoretical energy density and abundance of elemental sulfur. Nonetheless, there are several problems associated with Li-S batteries such as safety hazard due to lithium dendrite formation and fast capacity decay due to polysulfide dissolution effect. 1 Employment of solid-state electrolytes is a promising strategy to address those issues. Among different solid-state Li-ion electrolytes, Li-garnet attracts a lot of attention as it has a wide electrochemical window (> 6 V vs. Li/Li + ), and high ionic conductivity (~ 1 mS cm -1 ) at room temperature. However, the application of garnet is hampered by its interfacial resistance against electrodes. 2 In order to the reduce the interfacial area specific resistance (ASR) of Li/garnet interface, we devised a surfactant-processed interlayer for ceramic electrolytes (SPICE) method which can uniformly deposit a layer of ZnO onto the garnet surface. This process improves the wetting of Li and reduces the interfacial ASR to 10 Ω cm 2 at room temperature. 3 Stable Galvanostatic cycling of Li/garnet/Li at current densities up to 0.5 mA cm −2 was conducted, which presents a compelling method to solve the Li/solid electrolyte interface problem. Another strategy we applied is incorporating garnet into polymer matrix to fabricate a flexible hybrid electrolyte. Polymer-based electrolytes possess low interfacial resistance due to its intimate contact with electrodes. 4 The hybrid electrolyte merging the merits of garnet and polymer has been successfully employed in all-solid-state Li-S batteries operating at room temperature. Toward improving the energy density of the battery, we are working on tuning the cathode structure to effectively load more sulfur active materials. In this presentation, the SPICE method to tailor the interfacial resistance and the performance of all-solid-state Li-S batteries based on hybrid electrolyte will be discussed. Manthiram, A.; Fu, Y.; Chung, S.; Zu, C.; Su, Y. Chem. Rev. 2014 , 114 , 11751-11787. Han, X.; Gong, Y.; Fu, K.; He, X.; Hitz, G.; Dai, J.; Pearse, A.; Liu, B.; Wang, H.; Rubloff, G.; Mo, Y.; Thangadurai, V.; Wachsman, E.; Hu, L. Nat. Mater. 2016 , 16 , 572-579. Zhou, C.; Samson, A.; Hofstetter, K.; Thangadurai, V. Sustainable Energy & Fuels 2018 , 2 , 2165-2170. Zhou, C.; Bag, S.; Thangadurai, V. ACS Energy Lett. 2018 , 3 , 2181-2198.