High energy density of solid-state batteries requires a thin solid electrolyte separator layer (<30 μm), that can sustain high currents and is easily processable. Polymer-ceramic composite electrolytes can potentially fulfill these requirements by combining the advantages of each type. Ceramic electrolytes have high room-temperature ionic conductivity, transference number of one, and mechanical strength to suppress lithium dendrites, whereas polymer electrolytes are easily processable and can form conformable interfaces with the electrodes. High interfacial-impedance between polymer and ceramic electrolytes make the composites with dispersed ceramic particles less attractive.¹ A composite electrolyte architecture where a three-dimensionally interconnected porous ceramic is filled with polymer electrolyte, previously reported by our group, can avoid the interfacial impedance issue, although for thin composite membranes, the interfacial impedance between ceramic framework and excess polymer layer on top/bottom surface will still dominate the overall impedance.²

Here we will present fabrication and electrochemical evaluation of ~150 μm thick composite electrolytes with the above-described 3D-interconnected ceramic architecture. The 3-D framework is obtained by partially sintering Ohara ceramic particle tapes obtained via tape casting, which are filled with curable polymer electrolyte precursors. To obtain a thin (5 μm), uniform polymer electrolyte layer on both surfaces, spray coating was employed. The resulting composite membrane exhibited good dendritic resistance in symmetric cell cycling, improved transference number compared to the polymer electrolytes. We also found significantly improved flexibility of the composite electrolytes with plasticization, however, at the cost of reduction in ionic conductivity due to damage to the ceramic network caused by plasticizer-induced swelling of the cross-linked polymer electrolyte.

This research was sponsored by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy for the Vehicle Technologies Office’s Advanced Battery Materials Research Program (Tien Duong, Program Manager). This abstract has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

References

1. Chen, X. C.; Liu, X.; Samuthira Pandian, A.; Lou, K.; Delnick, F. M.; Dudney, N. J., Determining and Minimizing Resistance for Ion Transport at the Polymer/Ceramic Electrolyte Interface. ACS Energy Letters 2019, 4 (5), 1080-1085.
2. Palmer, M. J.; Kalnaus, S.; Dixit, M. B.; Westover, A. S.; Hatzell, K. B.; Dudney, N. J.; Chen, X. C., A three-dimensional interconnected polymer/ceramic composite as a thin film solid electrolyte. Energy Storage Materials 2020, 26, 242-249.