For pristine, cathode composite and fully charged samples, ex-situ X-ray absorption spectroscopy (XAS) experiments at Ni and Co K-edge were carried out at DESY (Deutsches Elektronen-Synchrotron) beamline P65 in Hamburg, Germany. The measurements were performed at the third undulator harmonic using a Si-coatedmirror to reject other harmonics, , a maximum synchrotron ring current of 100 mA and a Si(111) double crystal monochromator in continuous mode (300 s/spectrum). The samples were prepared and handled under an inert atmosphere as BN-diluted pellets, sealed in Kapton ® tape. Measurements on the Ni K-edge were carried out in transmission mode using a Ni-foil spectrum for energy calibration. Due to the lower Co concentration, the measurements were carried out in fluorescence geometry, whereby a Co foil spectrum was recorded before and after the measurements for energy calibration. For the La2Ni0.75Co0.25O4.08 samples charged at different cut off charging/discharging capacities, ex-situ high-energy-resolution fluorescence-detected X-ray absorption spectroscopy (HERFD-XAS) measurements at the Ni K-edge and the Co K-edge were carried out at beamline ID26 of the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. For the Co, first undulator harmonic was used. For the Ni, undulator third harmonic was used. Higher harmonics were rejected by Si coated mirrors. When using the third harmonic, the first harmonic was removed by a diamond attenuator. The incident energy was selected and monochromatized by a Si(111) reflection from a double crystal monochromator in a continuous scan mode of 60-120 s/spectrum and synchrotron beam current of 75 mA. Ni foil was used for the calibration of the incident energy. Three Si(531) analyzer crystals were used to select the Co Kα emission, and two Si(620) crystals for the Ni Kα emission. All crystals had a bending radius of 1 m and the emission was detected using an avalanche photodiode. The beam size was 0.1 x 0.2mm 2 (vertical x horizontal) and the total flux on the order of 5x10 12 photons/second. The intensity was normalized to the incident flux.