Research ArticleELECTROCHEMISTRY

Systems-level investigation of aqueous batteries for understanding the benefit of water-in-salt electrolyte by synchrotron nanoimaging

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Science Advances  06 Mar 2020:
Vol. 6, no. 10, eaay7129
DOI: 10.1126/sciadv.aay7129
  • Fig. 1 Experimental setup for operando TXM imaging of LiV3O8-LiMn2O4 aqueous Li-ion batteries.

    (A) Schematic showing the experimental layout. CCD, charge-coupled device. (B) Operando cell design and key components. (C) Photo of the operando TXM experiment. Photo credit: Yu-chen Karen Chen-Wiegart, Stony Brook University and Brookhaven National Laboratory.

  • Fig. 2 Electrochemical performance of the LiV3O8-LiMn2O4 couple.

    (A) Voltage profile of the 1 M LiTFSI:LiBETI electrolyte cell and the WIS electrolyte cell at 0.1 C during the first charge and discharge between 2.5 and 0.3 V. (B) Cycling behavior of the WIS electrolyte cell at 0.1 C between 2.5 and 0.3 V. (C) Voltage profile of the 1 M LiTFSI:LiBETI electrolyte cell and the WIS electrolyte cell at 1 C during the first charge and discharge between 2.0 and 0.3 V. (D) Cycling behavior of the WIS electrolyte cell at 1 C between 2.0 and 0.3 V. The rates are normalized by the capacity of the LiMn2O4 cathode, and the gravimetric capacity values are normalized by the mass of LiMn2O4.

  • Fig. 3 SEM and EDS characterizations of pristine and post-cycled electrodes.

    Surface morphological evolution of (A to F) the LiMn2O4 cathode and (H to M) the LiV3O8 anode. (A and H) Pristine states. (B and I) After one cycle at 0.1 C, 2.5 to 0.3 V, with the conventional 1 M LiTFSI:LiBETI electrolyte. (C and J) After 10 cycles at 0.1 C, 2.5 to 0.3 V, with the WIS electrolyte. (D to F and K to M) Higher-magnification SEM images of the electrodes in (A) to (C) and (H) to (J), respectively. EDS spectra collected on (G) LiMn2O4 electrodes and (N) LiV3O8 electrodes in pristine state after being cycled in the 1 M LiTFSI:LiBETI electrolyte and after being cycled in the WIS electrolyte.

  • Fig. 4 Operando imaging of LiV3O8-LiMn2O4 cell with the 1 M LiTFSI:LiBETI conventional aqueous electrolyte.

    (A) Image stack of delithiation. (B) Voltage profile of the cell and the image cross-correlation calculated by n frame and n + 1 frame, with n being the index of any given frame. (C to I) The TXM operando images collected from the cell at different time points labeled in (B). The particle displayed in (C) to (I) is marked with a white square in (A). (J) Decrease in x-ray attenuation during charging as particle undergoes a dissolution process. The ROIs displayed in (I) to (IV) are marked with green rectangles in (A); the color scales correspond to specific cycling state, as marked by (c-i). Videos of the full series of operando images including the full frame and the individual particle can be found in the Supplementary Materials.

  • Fig. 5 Operando imaging of LiV3O8-LiMn2O4 cell with the WIS electrolyte.

    (A) Image stack of full cycling. (B) Voltage profile of the cell and the image correlation calculated by n frame and n + 1 frame, with n being the index of any given frame. (C to I) The TXM operando images collected from the cell at the different time points labeled in (B). The particle displayed in (C) to (I) is marked with a white arrow in (A). (J) Evolutions of x-ray attenuation during a full cycle as particle shrinks in charging and expands in discharging. The ROIs displayed in (I) to (IV) are marked with red rectangles in (A); the color scales correspond to specific cycling state, as marked by (c-i). Videos of the full series of operando images including the full frame and the individual particle can be found in the Supplementary Materials.

  • Fig. 6 3D tomography and 2D XANES spectroscopic mapping of various states of LiMn2O4 electrodes in WIS system.

    (A) 3D nanotomographic reconstruction of a 20-μm electrode, fully charged (delithiated) at a rate of 0.5 C. (B) LiMn2O4 pristine state. (C) Ten-micrometer electrode, fully charged (delithiated) at a rate of 0.1 C, which delivered ~100% theoretical capacity. (D) Twenty-micrometer electrode, fully charged at a rate of 0.5 C, which delivered 85% theoretical capacity. Note that (D) is the projection of (A) at the x-z plane. (E) XANES spectra of selected regions (30 × 30 pixels) in (B) to (D); inset figure shows the spectra at the white line positions, which correspond to the oxidation state changes in the electrodes.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/10/eaay7129/DC1

    The conditions of FIB-SEM lift-out procedure

    Fig. S1. Characterizations of LiV3O8 powder and LiV3O8 half-cell.

    Fig. S2. Characterizations of LiMn2O4 powder and LiMn2O4 half-cell.

    Fig. S3. TXM images of LiMn2O4-LiV3O8 cell with the 1 M LiTFSI:LiBETI and WIS electrolyte collected above and below Mn K-edge.

    Fig. S4. Voltage profile versus TXM images of the operando LiV3O8-LiMn2O4 cell with the 1 M LiTFSI:LiBETI electrolyte.

    Fig. S5. Voltage profile versus TXM images of the operando LiV3O8-LiMn2O4 cell with the WIS electrolyte.

    Fig. S6. Measured area change of the tagged particle with the operando cell’s depth of discharge in Fig. 5.

    Fig. S7. The electrochemical profiles of two cells which LiMn2O4 electrodes were XANES imaged in Fig. 6.

    Fig. S8. The high-resolution SEM images corresponding to Fig. 3 (B and E).

    Fig. S9. The experimental setup for tomography and 2D XANES imaging.

    Fig. S10. The viscosity as a function of shear rate for the WIS electrolyte and the 1 M LiTFSI:LiBETI electrolyte.

    Fig. S11. Graphical abstract.

    Movie S1. Video of the full frame of 1 M aqueous electrolyte cell—Full field of view.

    Movie S2. Video of the full frame of 1 M aqueous electrolyte cell—Individual particle.

    Movie S3. Video of the full frame of the WIS electrolyte cell—Full field of view.

    Movie S4. Video of the full frame of the WIS electrolyte cell—Individual particle.

    Movie S5. Nanotomography of 20-μm-thick LiMn2O4 electrode cycled in the WIS electrolyte.

  • Supplementary Materials

    The PDF file includes:

    • The conditions of FIB-SEM lift-out procedure
    • Fig. S1. Characterizations of LiV3O8 powder and LiV3O8 half-cell.
    • Fig. S2. Characterizations of LiMn2O4 powder and LiMn2O4 half-cell.
    • Fig. S3. TXM images of LiMn2O4-LiV3O8 cell with the 1 M LiTFSI:LiBETI and WIS electrolyte collected above and below Mn K-edge.
    • Fig. S4. Voltage profile versus TXM images of the operando LiV3O8-LiMn2O4 cell with the 1 M LiTFSI:LiBETI electrolyte.
    • Fig. S5. Voltage profile versus TXM images of the operando LiV3O8-LiMn2O4 cell with the WIS electrolyte.
    • Fig. S6. Measured area change of the tagged particle with the operando cell’s depth of discharge in Fig. 5.
    • Fig. S7. The electrochemical profiles of two cells which LiMn2O4 electrodes were XANES imaged in Fig. 6.
    • Fig. S8. The high-resolution SEM images corresponding to Fig. 3 (B and E).
    • Fig. S9. The experimental setup for tomography and 2D XANES imaging.
    • Fig. S10. The viscosity as a function of shear rate for the WIS electrolyte and the 1 M LiTFSI:LiBETI electrolyte.
    • Fig. S11. Graphical abstract.

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). Video of the full frame of 1 M aqueous electrolyte cell—Full field of view.
    • Movie S2 (.mp4 format). Video of the full frame of 1 M aqueous electrolyte cell—Individual particle.
    • Movie S3 (.mp4 format). Video of the full frame of the WIS electrolyte cell—Full field of view.
    • Movie S4 (.mp4 format). Video of the full frame of the WIS electrolyte cell—Individual particle.
    • Movie S5 (.mp4 format). Nanotomography of 20-μm-thick LiMn2O4 electrode cycled in the WIS electrolyte.

    Files in this Data Supplement:

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