Research ArticleELECTROCHEMISTRY

Composite lithium electrode with mesoscale skeleton via simple mechanical deformation

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Science Advances  15 Mar 2019:
Vol. 5, no. 3, eaau5655
DOI: 10.1126/sciadv.aau5655
  • Fig. 1 Schematics of the electrode design.

    (A and B) Fabrication of composite Li electrode via mechanical deformation. (C) Tilted view of the resulting composite electrode disk showing alternating building blocks of Li strip and porous PE film. (D) Digital photo image of the composite Li electrode. Photo credit: Zheng Liang, Stanford University. (E) SEM image of the composite Li electrode.

  • Fig. 2 COMSOL multiphysics modeling of composite electrode geometry during Li stripping.

    (A) Schematic and top-view SEM image of the composite electrode at the initial stage and (B) corresponding initial state of the model. (C) Top-view SEM image of the composite electrode after stripping 1 mAh/cm2 of Li under a current density of 3 mA/cm2 and (D) corresponding slightly stripped model. (E) Top-view SEM image of the composite electrode after stripping 3 mAh/cm2 Li under a current density of 3 mA/cm2 and (F) corresponding increasingly stripped model. In the COMSOL modeling part, the width of each Li strip and PE film is around 50 and 12 μm, respectively, and the color scale represents the local Li+ ion concentration in millimolar (mM). Additional simulation parameters are available in the Supplementary Materials.

  • Fig. 3 Electrochemical performances of symmetric cells using control Li and composite Li electrodes.

    (A) Comparison of voltage profiles and (B) the corresponding hysteresis for cells using control and composite electrodes during Li plating/stripping processes under various current rates ranging from C/2 to 5C, where 1C is 1 mA/cm2. (C) Impedance spectroscopy of cells with control and composite electrodes before cycling and (D) after the first cycle. (E to G) Long-term cycling of control Li and composite Li symmetric cells with current densities of 1, 3, and 5 mA/cm2 and a deposition/stripping capacity of 1 mAh/cm2.

  • Fig. 4 Electrochemical performance of LCO full cells using control Li and composite Li electrodes.

    (A) Rate capability of a LCO/control Li cell and a LCO/spiral Li-50 cell under various current densities from C/5 to 5C. (B) Long-term cycling of a LCO/Control Li cell and a LCO/spiral Li-50 cell at 2C. The full cell was first activated at a low rate of C/5 for 3 cycles. (C) Voltage profiles of a LCO/control Li cell and a LCO/spiral Li-50 cell at a current rate of 2C at the 20th cycle. The inset is enlarged voltage curve at initial charging stage.

  • Fig. 5 SEM images of the pristine and cycled composite Li electrode.

    (A) Top-view SEM images of the pristine composite Li electrode. (B) Top-view SEM images of the composite Li electrode after 10 cycles at 3 mA/cm2 for a total of 1 mAh/cm2. (C) Top-view SEM images of the composite Li electrode after 100 cycles at 3 mA/cm2 for a total of 1 mAh/cm2. (D) Side-view SEM images of the pristine composite electrode through unwrapping the electrode. (E) Side-view SEM images of the composite electrode after cycling under a current density of 3 mA/cm2 for a total of 1 mAh/cm2.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/3/eaau5655/DC1

    Fig. S1. Effect of Li strip thickness on the electrochemical performance of the composite electrode.

    Fig. S2. Schematics and the corresponding SEM characterization of dense composite Li electrode with nonporous PE film as the skeleton.

    Fig. S3. Li stripping on composite Li electrode with porous and dense PE films.

    Fig. S4. Comparison of long-term cycling of symmetric cells.

    Fig. S5. Morphology comparison of Li electrode center part with outer region, before and after cycling.

    Fig. S6. Characterizations of crystalline PI film.

    Fig. S7. Li stripping study of composite Li electrode without crystal PI support.

    Fig. S8. Li stripping study of composite Li electrode with rigid PI support.

    Fig. S9. Symmetric cycling of control Li electrode, composite Li electrode without PI support, and composite electrode with PI support.

    Fig. S10. High-capacity symmetric cycling of various electrodes under a high current density of 8 mA/cm2 for a total of 32 mAh/cm2 in an EC/DEC electrolyte containing 10% FEC and 1% VC.

    Fig. S11. Detailed information about Li usage for both composite Li and control Li anode and the related calculations.

    Fig. S12. The magnified simulation cell geometry in COMSOL.

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Effect of Li strip thickness on the electrochemical performance of the composite electrode.
    • Fig. S2. Schematics and the corresponding SEM characterization of dense composite Li electrode with nonporous PE film as the skeleton.
    • Fig. S3. Li stripping on composite Li electrode with porous and dense PE films.
    • Fig. S4. Comparison of long-term cycling of symmetric cells.
    • Fig. S5. Morphology comparison of Li electrode center part with outer region, before and after cycling.
    • Fig. S6. Characterizations of crystalline PI film.
    • Fig. S7. Li stripping study of composite Li electrode without crystal PI support.
    • Fig. S8. Li stripping study of composite Li electrode with rigid PI support.
    • Fig. S9. Symmetric cycling of control Li electrode, composite Li electrode without PI support, and composite electrode with PI support.
    • Fig. S10. High-capacity symmetric cycling of various electrodes under a high current density of 8 mA/cm2 for a total of 32 mAh/cm2 in an EC/DEC electrolyte containing 10% FEC and 1% VC.
    • Fig. S11. Detailed information about Li usage for both composite Li and control Li anode and the related calculations.
    • Fig. S12. The magnified simulation cell geometry in COMSOL.

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