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Understanding the Surface Regeneration and Reactivity of Garnet Solid-State Electrolytes.

Accepted version
Peer-reviewed

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Article

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Authors

Nagendran, Supreeth  ORCID logo  https://orcid.org/0000-0002-9843-0214
Karagoz, Burcu 
Sternemann, Christian  ORCID logo  https://orcid.org/0000-0001-9415-1106

Abstract

Garnet solid-electrolyte-based Li-metal batteries can be used in energy storage devices with high energy densities and thermal stability. However, the tendency of garnets to form lithium hydroxide and carbonate on the surface in an ambient atmosphere poses significant processing challenges. In this work, the decomposition of surface layers under various gas environments is studied by using two surface-sensitive techniques, near-ambient-pressure X-ray photoelectron spectroscopy and grazing incidence X-ray diffraction. It is found that heating to 500 °C under an oxygen atmosphere (of 1 mbar and above) leads to a clean garnet surface, whereas low oxygen partial pressures (i.e., in argon or vacuum) lead to additional graphitic carbon deposits. The clean surface of garnets reacts directly with moisture and carbon dioxide below 400 and 500 °C, respectively. This suggests that additional CO2 concentration controls are needed for the handling of garnets. By heating under O2 along with avoiding H2O and CO2, symmetric cells with less than 10 Ωcm2 interface resistance are prepared without the use of any interlayers; plating currents of >1 mA cm-2 without dendrite initiation are demonstrated.

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Keywords

40 Engineering, 4016 Materials Engineering, 34 Chemical Sciences, 3406 Physical Chemistry, 7 Affordable and Clean Energy

Journal Title

ACS Energy Lett

Conference Name

Journal ISSN

2380-8195
2380-8195

Volume Title

Publisher

American Chemical Society (ACS)
Sponsorship
European Commission Horizon 2020 (H2020) ERC (835073)
Faraday Institution (FIRG016)
Faraday Institution (via University Of Bath) (FIRG016)
Faraday Institution (via University Of Bath) (FIRG016)
Faraday Institution (FIRG016)
Faraday Institution (via University of Oxford) (CATMAT)
Royal Society (RP/R1/180147)
S.V. acknowledges funding from the Cambridge Commonwealth European and International Trust, Faraday Institution (SOLBAT, FIRG007) and Royal Society (RP/R1/180147). F.N.S also acknowledges funding from The Faraday Institution CATMAT project (FIRG016). S.N. thanks the Royal Society (United Kingdom) and Science and Engineering Research Board (Government of India) for the award of Newton-Bhabha International Fellowship (NIF/R1/180075). C.P.G thanks the EU via an Advanced EU ERC grant (EC H2020 835073). Professor Norman Fleck and Professor Vikram Deshpande are thanked for access to their laboratories for sample preparation and for helpful discussions. We thank Simon Marshall and Graham Smith for assistance in operating hot-press and Anthony Dennis and Harry Druiff for assistance in cutting hot-pressed samples. We thank Diamond Light Source, UK for access to beamline B07 (SI29728) for NAP-XPS measurements and DELTA, Germany for providing synchrotron radiation at beamline BL9 for grazing incidence X-ray diffraction measurements. We also acknowledge I11 beamline for synchrotron XRD at Diamond Light Source, UK under BAG proposal (CY28349).