title: Investigating the Dendritic Growth during Full Cell Cycling of Garnet Electrolyte in Direct Contact with Li Metal.
abstract: All-solid-state batteries including a garnet ceramic as electrolyte are potential candidates to replace the currently used Li-ion technology, as they offer safer operation and higher energy storage performances. However, the development of ceramic electrolyte batteries faces several challenges at the electrode/electrolyte interfaces, which need to withstand high current densities to enable competing C-rates. In this work, we investigate the limits of the anode/electrolyte interface in a full cell that includes a Li-metal anode, LiFePO4cathode, and garnet ceramic electrolyte. The addition of a liquid interfacial layer between the cathode and the ceramic electrolyte is found to be a prerequisite to achieve low interfacial resistance and to enable full use of the active material contained in the porous electrode. Reproducible and constant discharge capacities are extracted from the cathode active material during the first 20 cycles, revealing high efficiency of the garnet as electrolyte and the interfaces, but prolonged cycling leads to abrupt cell failure. By using a combination of structural and chemical characterization techniques, such as SEM and solid-state NMR, as well as electrochemical and impedance spectroscopy, it is demonstrated that a sudden impedance drop occurs in the cell due to the formation of metallic Li and its propagation within the ceramic electrolyte. This degradation process is originated at the interface between the Li-metal anode and the ceramic electrolyte layer and leads to electromechanical failure and cell short-circuit. Improvement of the performances is observed when cycling the full cell at 55 °C, as the Li-metal softening favors the interfacial contact. Various degradation mechanisms are proposed to explain this behavior.
authors.affiliation: CIC Energigune, Parque Tecnológico de Álava, C/Albert Einstein 48, 01510, Miñano, Spain.
authors.forename: Frederic
authors.identifier: http://orcid.org/0000-0002-5675-0711
authors.initials: F
authors.lastname: Aguesse
authors.affiliation: CIC Energigune, Parque Tecnológico de Álava, C/Albert Einstein 48, 01510, Miñano, Spain.
authors.forename: William
authors.initials: W
authors.lastname: Manalastas
authors.affiliation: CIC Energigune, Parque Tecnológico de Álava, C/Albert Einstein 48, 01510, Miñano, Spain.
authors.forename: Lucienne
authors.initials: L
authors.lastname: Buannic
authors.affiliation: CIC Energigune, Parque Tecnológico de Álava, C/Albert Einstein 48, 01510, Miñano, Spain.
authors.forename: Juan Miguel
authors.initials: JM
authors.lastname: Lopez Del Amo
authors.affiliation: CIC Energigune, Parque Tecnológico de Álava, C/Albert Einstein 48, 01510, Miñano, Spain.
authors.forename: Gurpreet
authors.initials: G
authors.lastname: Singh
authors.affiliation: CIC Energigune, Parque Tecnológico de Álava, C/Albert Einstein 48, 01510, Miñano, Spain.|IKERBASQUE, Basque Foundation for Science , Maria Diaz de Haro 3, 48013, Bilbao, Spain.
authors.forename: Anna
authors.identifier: http://orcid.org/0000-0003-4169-9156
authors.initials: A
authors.lastname: Llordés
authors.affiliation: CIC Energigune, Parque Tecnológico de Álava, C/Albert Einstein 48, 01510, Miñano, Spain.|Department of Materials, Imperial College London , Exhibition Road, SW7 2AZ, London, U.K.
authors.forename: John
authors.initials: J
authors.lastname: Kilner
keywords: Li-metal/garnet interface; all-solid-state batteries; degradation mechanisms; dendritic lithium formation; full cell cycling; garnet electrolyte; post mortem analysis