Nanostructural and Electrochemical Evolution of the Solid-Electrolyte Interphase on CuO Nanowires Revealed by Cryogenic-Electron Microscopy and Impedance Spectroscopy

Journal Article · Thu Dec 27 00:00:00 EST 2018 · ACS Nano

DOI:https://doi.org/10.1021/acsnano.8b08012· OSTI ID:1503645

Huang, William  ^[1]; Boyle, David T.  ^[1]; Li, Yuzhang  ^[1]; Li, Yanbin  ^[1]; Pei, Allen  ^[1]; Chen, Hao  ^[1]; Cui, Yi  ^[2]

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1. Stanford Univ., Stanford, CA (United States)
2. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)

Battery performance is critically dependent on the nanostructure and electrochemical properties of the solid-electrolyte interphase (SEI)—a passivation film that exists on most lithium-battery anodes. However, knowledge of how the SEI nanostructure forms and its impact on ionic transport remains limited due to its sensitivity to transmission electron microscopy and difficulty in accurately probing the SEI impedance. Here, we track the voltage-dependent, stepwise evolution of the nanostructure and impedance of the SEI on CuO nanowires using cryogenic-electron microscopy (cryo-EM) and electrochemical impedance spectroscopy (EIS). In carbonate electrolyte, the SEI forms at 1.0 V vs Li/Li⁺ as a 3 nm thick amorphous SEI and grows to 4 nm at 0.5 V; as the potential approaches 0.0 V vs Li/Li⁺, the SEI on the CuO nanowires forms an 8 nm thick inverted multilayered nanostructure in ethylene carbonate/diethyl carbonate (EC/DEC) electrolyte with 10 vol % fluoroethylene carbonate (FEC) and a mosaic nanostructure in EC/DEC electrolyte. Upon Li deposition, the total SEI thickness grows to 16 nm, and significant growth of the inner amorphous layer takes place in the inverted multilayered nanostructure, indicating that electrolyte permeates the SEI. Using a refined EIS methodology, we isolate the SEI impedance on Cu and find that the SEI nanostructure directly correlates to macroscopic Li-ion transport through the SEI. The inverted layered nanostructure decreases the interfacial impedance upon formation, whereas the mosaic nanostructure continually increases the interfacial impedance during growth. Furthermore these structural and electrochemical findings illustrate a more complete portrait of SEI formation and guide further improvements in engineered SEI.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
• Grant/Contract Number: AC02-76SF00515
• OSTI ID: 1503645
• Journal Information: ACS Nano, Vol. 13, Issue 1; ISSN 1936-0851
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
25 ENERGY STORAGE
batteries
cryogenic-electron microscopy
lithium-ion batteries
lithium-metal anode
solid-electrolyte interphase
transmission electron microscopy