Investigating the Cyclability and Stability at the Interfaces of Composite Solid Electrolytes in Li Metal Batteries

Sarah E Holmes; Fang Liu; Wenbo Zhang; Philaphon Sayavong; Solomon T Oyakhire; Yi Cui

doi:10.1021/acsami.2c14677

Investigating the Cyclability and Stability at the Interfaces of Composite Solid Electrolytes in Li Metal Batteries

ACS Appl Mater Interfaces. 2022 Dec 7;14(48):53736-53743. doi: 10.1021/acsami.2c14677. Epub 2022 Nov 23.

Authors

Sarah E Holmes¹, Fang Liu^{2

3}, Wenbo Zhang³, Philaphon Sayavong¹, Solomon T Oyakhire⁴, Yi Cui^{2

5}

Affiliations

¹ Department of Chemistry, Stanford University, Stanford, California94305, United States.
² Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin53706, United States.
³ Department of Materials Science and Engineering, Stanford University, Stanford, California94305, United States.
⁴ Department of Chemical Engineering, Stanford University, Stanford, California94305, United States.
⁵ Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California94025, United States.

PMID: 36416366
DOI: 10.1021/acsami.2c14677

Abstract

Despite the fact that much work has been dedicated to finding the ideal additive for composite solid electrolytes (CSEs) for lithium-based solid-state batteries, little is known about the properties of a CSE that enable stable cycling with a lithium metal anode. In this work, we use three CSEs based on lithium nitride (Li₃N), a fast lithium-ion conductor, and lithium hydroxide (LiOH) to investigate the properties and interfacial interactions that impact the cyclability of CSEs. We present a method for stabilizing Li₃N with a shell of LiOH, and we incorporate Li₃N, core-shell particles, and LiOH into CSEs using polyethylene oxide (PEO) and lithium bis(trifluoromethanesulfonyl)imide. Through improved interfacial chemistry, CSEs with core-shell particles have superior electrochemical cycling performance compared to those with unprotected Li₃N in symmetric Li-Li cells. This CSE features a high ionic conductivity of 0.66 mS cm^-1 at 60 °C, a high critical current density of 1.2 mA cm^-2, and a wide voltage window of 0-5.1 V. Full cells with the core-shell CSE and lithium iron phosphate cathodes exhibit stable cycling and high reversible specific capacities in cells as high as 2.5 mAh cm^-2. We report that the improved ionic conductivity and amorphous PEO content have a limited effect on the solid-state electrolyte performance, while improving the electrolyte-Li metal anode interface is key to cycling longevity.

Keywords: composite solid−electrolyte; lithium metal battery; solid-state; solid−electrolyte interface; stability.