Fig. 2

First cycle average STXM-XAS of LMR-NMC. a dQ dV⁻¹ of the first cycle showing the voltages at which samples were harvested for STXM. The samples are pristine (P), 4.35 V (1), 4.60 V (2), 3.65 V (3), and 2.00 V (4). Regions of the dQ dV⁻¹ are shaded to show the hysteresis in the O redox relative to the TM–O redox. b Schematic and spectra comparing STXM-XAS to various other XAS detection modes (TEY, FY, and fluorescence yield X-ray microscopy, FY-XRM⁸⁷). The FY-XRM spectrum was collected on the same sample as the STXM spectrum, confirming sample preparation is not the cause of the discrepancy. c–f Spatially averaged transmission soft XAS throughout the first cycle at the c O K, d Ni L₃, e Co L₃, and f Mn L₃ edges, obtained by summing the spectra of all the pixels containing active material in each STXM spectro-image. Solid traces indicate electrodes harvested during charge, while dashed traces indicate electrodes harvested during discharge. The red and black traces below each plot indicate the differential spectra between the points indicated