In situ visualization of Li/Ag2VP2O8 batteries revealing rate-dependent discharge mechanism by Kevin Kirshenbaum, David C. Bock, Chia-Ying Lee, Zhong Zhong, Kenneth J. Takeuchi, Amy C. Marschilok, and Esther S. Takeuchi Science Volume 347(6218):149-154 January 9, 2015 Published by AAAS

Fig. 1 Experimental setup and EDXRD spectra resulting from in situ measurements.EDXRD spectra obtained within three coin cells: (A) the nondischarged cell, (B and C) two different locations within a cell discharged to 0.5 elec. equiv. at C/1440, and (D to F) three different locations within a cell discharged to 0.5 elec. equiv. at C/168. Experimental setup and EDXRD spectra resulting from in situ measurements.EDXRD spectra obtained within three coin cells: (A) the nondischarged cell, (B and C) two different locations within a cell discharged to 0.5 elec. equiv. at C/1440, and (D to F) three different locations within a cell discharged to 0.5 elec. equiv. at C/168. Spectra were obtained every 20 μm through the cathode; for clarity, only half of the scans are presented in the figure. Spectra toward the top of the figure (red hues) were obtained within the side of the cathode closer to the stainless steel coil cell top, and spectra toward the bottom of the figure (black hues) were obtained closer to the Li anode. Kevin Kirshenbaum et al. Science 2015;347:149-154 Published by AAAS

Fig. 2 Intensities of Ag and Ag2VP2O8 and crystallite size of Ag as a function of beam position along the z direction.(A) Cathode discharged to 0.5 elec. equiv. at the faster rate (C/168). Intensities of Ag and Ag2VP2O8 and crystallite size of Ag as a function of beam position along the z direction.(A) Cathode discharged to 0.5 elec. equiv. at the faster rate (C/168). Three x-direction locations were measured (see schematic inset). arb., arbitrary units. (B) Cathode discharged to 0.5 elec. equiv. at the slower rate (C/1440). Two locations along the x direction were measured in this cell (see schematic inset). Error bars represent the uncertainty in the fit (see supplementary materials). Kevin Kirshenbaum et al. Science 2015;347:149-154 Published by AAAS

Fig. 3 Ex situ XRD patterns of Ag2VP2O8 cathodes Fig. 3 Ex situ XRD patterns of Ag2VP2O8 cathodes.(A) Spectra were obtained from cells discharged at the slower rate (C/1440) to 0.1 and 0.5 elec. equiv. Ex situ XRD patterns of Ag2VP2O8 cathodes.(A) Spectra were obtained from cells discharged at the slower rate (C/1440) to 0.1 and 0.5 elec. equiv.. (B) Spectra were obtained from cells discharged at the faster rate (C/168). (C) Area of the Ag(111) peak and crystallite size, as determined by the peak width. Error bars represent the uncertainty in the fit (see supplementary materials). Kevin Kirshenbaum et al. Science 2015;347:149-154 Published by AAAS

Fig. 4 X-ray absorption (XAS) and fluorescence (XRF) measurements of partially discharged Ag2VP2O8.Data in this figure are from cells discharged to 0.1 and 0.5 elec. equiv. at C/1440 (slow rate, S) and 0.1, 0.5, and 1.0 elec. equiv. at C/168 (fast rate, F), as well as Ag2VP2O8 and Ag standards. X-ray absorption (XAS) and fluorescence (XRF) measurements of partially discharged Ag2VP2O8.Data in this figure are from cells discharged to 0.1 and 0.5 elec. equiv. at C/1440 (slow rate, S) and 0.1, 0.5, and 1.0 elec. equiv. at C/168 (fast rate, F), as well as Ag2VP2O8 and Ag standards. (A) Normalized absorption at the Ag K-edge. (B) Ag K-edge near-edge region. Arrows point to isosbestic points supporting the existence of a two-phase system (Ag+ →Ag0). (C) Normalized fluorescence of V K-edge. (Inset) Pre-edge peak showing no change in peak height or position until DOD reached 1.0 elec. equiv. (D) Post-edge white line for normalized fluorescence data highlighting the dependence of the shoulder feature on DOD and discharge rate. (Inset) Normalized fluorescence of the V K-edge. The dashed box shows the region that is emphasized in the figure. Kevin Kirshenbaum et al. Science 2015;347:149-154 Published by AAAS

Fig. 5 Linear combination fits of data from Fig. 4.(A) Ag K-edge. Linear combination fits of data from Fig. 4.(A) Ag K-edge. (B) V K-edge. Error bars represent the uncertainty in the fit (see supplementary materials). (Insets) Enhancement of the linear combination fit results up to 1 elec. equiv. Kevin Kirshenbaum et al. Science 2015;347:149-154 Published by AAAS