Integrated Multi-scale Synchrotron Radiation Technology Studies on AlPO4 Coating Modification Mechanism in Lithium-rich Manganese-based Cathode

This is the data of the article titled Integrated Multi-scale Synchrotron Radiation Technology Studies on AlPO4 Coating Modification Mechanism in Lithium-rich Manganese-based Cathode.Figure 1 shows the basic morphology and structural information of the LMR material before and after coating:Figure 1a （XRD patterns of pristine LMR and LMR@0.5% APO samples） was get for phase analysis using Bruker D8 advance X (Cu-Kα radiation, λ=1.542 Å) in the 2θ range of 10-80° at room temperature.Figure 1b, c (the Al 2p and P 2p XPS spectrum of LMR@0.5% APO sample) was obtained for elemental composition information on a Thermo ESCALAB250 instrument.Figure 1d, e, f (SEM and EDS images of pristine LMR and LMR@0.5% APO samples) was obtained to observe the morphology of the samples, using Scanning electron microscopy (SEM, S-4800N, Hitachi).Figure 1g, h (HRTEM images of pristine LMR and LMR@0.5% APO samples) was obtained for the bulk structure of samples, using a Tecnai G2 F20 S-TWIN, FEI transmission electron microscope. Figure 2 shows the electrochemical performance of the LMR material before and after coating. The electrochemical performance tests were carried out using coin-type 2025 cells. Both cathode materials were meticulously composed of a mixture containing 80 wt% active material, 10 wt% poly (vinylidene difluoride) (PVDF) binder in a precise amount of N-methyl-2-pyrrolidone (NMP), 5 wt% Super P, and 5 wt% Vapor-grown carbon fiber. The resulting slurry was uniformly cast onto aluminum foil and dried overnight at 70°C under vacuum conditions to remove the NMP. Then disc electrodes with a diameter of 12 mm were punched from the coated foil, achieving an average active material mass loading of 2.5-3.5 mg cm-2. The assembly of the half-cell was performed in an argon-enriched glovebox to ensure a contamination-free environment, utilizing pure lithium as the counter electrode. Additionally, polypropylene membrane (Celgard-2400) was implemented as the separator. The electrolyte solution consisted of 1 M LiPF6 dissolved in a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) in a volumetric ratio of 1:1:1. Precisely 100 μL of this kind of electrolyte was added each coin cell to maintain uniform electrochemical performance. All measurements for the electrochemical testing of the coin-type cells were performed at ambient room temperature. Galvanostatic cycling tests were performed at a constant current density of 1 C (1 C = 250 mAh g-1) over 2.0–4.6 V using a NEWARE battery-testing system.Figure 2a is the cycle performance of pristine LMR and LMR@0.5% APO samples at 1 C.Figure 2b, c are the initial charge and discharge curves and dQ/dV curves of pristine LMR and LMR@0.5% APO samples at 0.1 C.Figure2d, e are the dQ/dV curves of pristine LMR and LMR@0.5% APO samples from the 3rd to 200th cycle at 1C. Figure 3 shows the evolution of the surface of the samples. The ex-situ hXAS test for the Mn K-edge of the LMR sample was carried out at Shanghai Synchrotron Radiation Facility (SSRF) BL16U1 beamline, with a photon flux of 3.7×1012 photons s-1 at the sample position, using transmission mode. Calibration was carried out using the Mn K-edge data of standard Mn foil. The Mn L-edge sXAS of LMR sample was collected at SSRF BL08U1A beamline, using the TEY (Total Electron Yield) mode, with photon fluxes of 1.5×108 photons s-1 and the pressure range of 10-6 Torr. Calibration was carried out using the Mn L-edge data of the standard MnO2 sample. The XAS data were all processed using the Athena software from IFEFFIT software package for energy calibration, noise removal, background subtraction and normalization.Figure 3a is the initial charge and discharge curve of the pristine LMR sample.Figure 3b is the ex-situ hard XANES spectra at Mn K-edge for pristine LMR sample during the first cycle.Figure 3c, d are the ex-situ soft XANES spectra and differential spectra at Mn L-edge for pristine LMR sample during the first cycle. Figure 3d is the soft XANES spectra at Mn L-edge for pristine LMR sample after 200 cycles.Figure 3e, f are the ex-situ soft XANES spectra at Mn L-edge for pristine LMR and LMR@0.5% APO samples during the first cycle. Figure 4 shows the change in bulk structure of the samples. The hXAS test for the Mn K-edge of long-cycling LMR samples was tested at SSRF BL14W beamline, with a photon flux of 2.6×1012 photons s-1 at the sample position, using transmission mode. Calibration was carried out by using the Mn K-edge data of standard Mn foil. The XAS data were all processed by using the Athena software from IFEFFIT software package for energy calibration, noise removal, background subtraction and normalization. The wavelet transform was carried out by using the wtEXAFS software with k2 weighting.Figure 4a, b are the XANES spectra at Mn K-edge of cycled pristine LMR and LMR@0.5% APO samples.Figure 4c, d are the FT-EXAFS spectra at Mn K-edge of cycled pristine LMR and LMR@0.5% APO samples.The Figure 4e, f are the wt-EXAFS spectra at Mn K-edge of pristine LMR and LMR@0.5% APO samples.Figure 4g, h are the wt-EXAFS spectra at Mn K-edge of pristine LMR and LMR@0.5% APO samples after 200 cycles. Figure 5 shows the distribution of valence states by using TXM-XANES. The Mn K-edge TXM-XANES test of LMR samples was carried out at SSRF BL18B beamline, with a photon flux of 1.3×1010 photons s-1 at the sample position, a field of view of approximately 20 μm×20 μm, and a spatial resolution of 60 nm (pixel scale: 30 nm). The active material from the electrode sheet obtained from batteries disassembled in an argon-filled glove box, was scraped off with a scalpel, then placed into a blue-capped vial and DMC solvent was added. After sealing the blue-capped vial, it was taken out of the glove box for ultrasonication. Finally, before the test, the sample was delivered into the micro-tip of glass tube using an industrial dispenser. The TXM-XANES data were all processed by using the TXM-wizard and matlab software.Figure 5a, b are the 2D valence state mappings  at Mn K-edge of the pristine and cycled LMR samples.Figure 5d, e are the 2D valence state mappings  at Mn K-edge of the pristine and cycled LMR@0.5% APO samples.The figure 5c, f are the pixel energy distribution histogram of pristine LMR and LMR@0.5% APO samples after 200 cycles. Figure 6 shows the structural changes caused by anionic redox reactions at high voltage from surface to bulk. The ex-situ hXAS test for the Mn K-edge of the LMR sample was carried out at SSRF BL16U1 beamline, with a photon flux of 3.7×1012 photons s-1 at the sample position, using transmission mode. The ex-situ hXAS test for the Ni K-edge and Co K-edge of the LMR sample was carried out at SSRF BL20U1 beamline, with a photon flux of 1012 photons s-1 at the sample position, both using fluorescence mode. All hXAS tests were calibrated using the K-edge data of transition metal foils corresponding to the tested elements. The O K-edge sXAS was tested at SSRF BL02B02 beamline using a combined TEY and TFY (Total Fluorescence Yield) mode, with a photon flux at the sample position of 3×1010 photons s-1 and the pressure range of 5×10-9 Torr. Calibration was conducted using the O K-edge data of the standard SrTiO3 sample. The XAS data were all processed using the Athena software from IFEFFIT software package for energy calibration, noise removal, background subtraction and normalization.Figure 6a, b are ex-situ soft XANES spectra in TEY mode at O K-edge of pristine LMR and LMR@0.5% APO samples.Figure 6c, d are ex-situ soft XANES spectra in TFY mode at O K-edge of pristine LMR and LMR@0.5% APO samples.Figure 6e, f are ex-situ hard XANES spectra at Mn K-edge of pristine LMR and LMR@0.5% APO samples.Figure 6g, h are ex-situ FT-EXAFS spectra at Mn K-edge of pristine LMR and LMR@0.5% APO samples.Figure 6i, j are ex-situ hard XANES spectra at Ni K-edge of pristine LMR and LMR@0.5% APO samples.Figure 6k, l are ex-situ FT-EXAFS spectra at Ni K-edge of pristine LMR and LMR@0.5% APO samples.Figure 6m, n are ex-situ hard XANES spectra at Co K-edge of pristine LMR and LMR@0.5% APO samples.Figure 6o, p are ex-situ FT-EXAFS spectra at Co K-edge of pristine LMR and LMR@0.5% APO samples. Figure S1-Figure S8 are the data form the supporting information. All data are processed like the same kind of data in Figure 1-Figure 6.