Design and Sintering of All-Solid-State Composite Cathodes with Tunable Mixed Conduction Properties via the Cold Sintering Process

Electrodes for solid-state batteries require the conduction of both ions and electrons for extraction of the energy from the active material. In this study, we apply cold sintering to a model composite cathode system to study how low-temperature densification enables a degree of control over the mixed conducting properties of such systems. The model system contains the NASICON-structured Na3V2(PO4)3 (NVP) active material, NASICON-structured solid electrolyte (Na3Zr2Si2PO12, NZSP), and electron-conducting carbon nanofiber (CNF). Pellets of varying weight fractions of components were cold-sintered to greater than 90% of the theoretical density at 350-375 °C, a 360 MPa uniaxial pressure, and with a 3 h dwell time using sodium hydroxide as the transient sintering aid. The bulk conductivity of the diphasic composites was measured with impedance spectroscopy; the total conductivities of the composites are increased from 3.8 × 10^(-8) S·cm^(-1) (pure NVP) to 5.81 × 10^(-6) S·cm^(-1) (60 wt % NZSP) and 1.31 × 10^(-5) S·cm^(-1) (5 wt % CNF). Complimentary direct current polarization experiments demonstrate a rational modulation in transference number (τ) of the composites; τ of pure NVP = 0.966, 60 wt % NZSP = 0.995, and 5 wt % CNF = 0.116. Finally, all three materials are combined into triphasic composites to serve as solid-state cathodes in a half-cell configuration with a liquid electrolyte. Electrochemical activity of the active material is maintained, and the capacity/energy density is comparable to prior work.

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Work Title Design and Sintering of All-Solid-State Composite Cathodes with Tunable Mixed Conduction Properties via the Cold Sintering Process
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Open Access
Creators
  1. Zane Grady
  2. Zhongming Fan
  3. Arnaud Ndayishimiye
  4. Clive A. Randall
Keyword
  1. Solid-state batteries
  2. Sintering
  3. Composite electrodes
  4. Mixed conduction
  5. Solid electrolyte
License In Copyright (Rights Reserved)
Work Type Article
Publisher
  1. ACS Applied Materials & Interfaces
Publication Date September 28, 2021
Publisher Identifier (DOI)
  1. https://doi.org/10.1021/acsami.1c13913
Deposited August 02, 2022

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Version 1
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  • Created
  • Added Grady-ACS-Appl.MatIntfc-Sept._2021.pdf
  • Added Creator Zane Grady
  • Added Creator Zhongming Fan
  • Added Creator Arnaud Ndayishimiye
  • Added Creator Clive A. Randall
  • Published
  • Updated Keyword, Publisher, Description, and 1 more Show Changes
    Keyword
    • Solid-state batteries, Sintering, Composite electrodes, Mixed conduction, Solid electrolyte
    Publisher
    • ACS applied materials & interfaces
    • ACS Applied Materials & Interfaces
    Description
    • <p>Electrodes for solid-state batteries require the conduction of both ions and electrons for extraction of the energy from the active material. In this study, we apply cold sintering to a model composite cathode system to study how low-temperature densification enables a degree of control over the mixed conducting properties of such systems. The model system contains the NASICON-structured Na3V2(PO4)3 (NVP) active material, NASICON-structured solid electrolyte (Na3Zr2Si2PO12, NZSP), and electron-conducting carbon nanofiber (CNF). Pellets of varying weight fractions of components were cold-sintered to greater than 90% of the theoretical density at 350-375 °C, a 360 MPa uniaxial pressure, and with a 3 h dwell time using sodium hydroxide as the transient sintering aid. The bulk conductivity of the diphasic composites was measured with impedance spectroscopy; the total conductivities of the composites are increased from 3.8 × 10-8 S·cm-1 (pure NVP) to 5.81 × 10-6 S·cm-1 (60 wt % NZSP) and 1.31 × 10-5 S·cm-1 (5 wt % CNF). Complimentary direct current polarization experiments demonstrate a rational modulation in transference number (τ) of the composites; τ of pure NVP = 0.966, 60 wt % NZSP = 0.995, and 5 wt % CNF = 0.116. Finally, all three materials are combined into triphasic composites to serve as solid-state cathodes in a half-cell configuration with a liquid electrolyte. Electrochemical activity of the active material is maintained, and the capacity/energy density is comparable to prior work.</p>
    • <p>Electrodes for solid-state batteries require the conduction of both ions and electrons for extraction of the energy from the active material. In this study, we apply cold sintering to a model composite cathode system to study how low-temperature densification enables a degree of control over the mixed conducting properties of such systems. The model system contains the NASICON-structured Na3V2(PO4)3 (NVP) active material, NASICON-structured solid electrolyte (Na3Zr2Si2PO12, NZSP), and electron-conducting carbon nanofiber (CNF). Pellets of varying weight fractions of components were cold-sintered to greater than 90% of the theoretical density at 350-375 °C, a 360 MPa uniaxial pressure, and with a 3 h dwell time using sodium hydroxide as the transient sintering aid. The bulk conductivity of the diphasic composites was measured with impedance spectroscopy; the total conductivities of the composites are increased from 3.8 × 10^(-8) S·cm^(-1) (pure NVP) to 5.81 × 10^(-6) S·cm^(-1) (60 wt % NZSP) and 1.31 × 10^(-5) S·cm^(-1) (5 wt % CNF). Complimentary direct current polarization experiments demonstrate a rational modulation in transference number (τ) of the composites; τ of pure NVP = 0.966, 60 wt % NZSP = 0.995, and 5 wt % CNF = 0.116. Finally, all three materials are combined into triphasic composites to serve as solid-state cathodes in a half-cell configuration with a liquid electrolyte. Electrochemical activity of the active material is maintained, and the capacity/energy density is comparable to prior work.</p>
    Publication Date
    • 2021-10-13
    • 2021-09-28
  • Updated