The first cycle voltage profiles and gas evolution rates of a LNMO and b LNRO.The total active cathode material used for the measurement was 32.9 mg LNMO (387 μmol) and 28.6 mg LNRO (253 μmol).Recent research has explored combining conventional transition-metal redox with anionic lattice oxygen redox as a new and exciting direction to search for high-capacity lithium-ion cathodes.Here, we probe the poorly understood electrochemical activity of anionic oxygen from a material perspective by elucidating the effect of the transition metal on oxygen redox activity.
To further confirm the similar crystal structure between LNMO and LNRO, high-resolution synchrotron XRD patterns were refined by the conventional Rietveld method (Fig. Our refinements were performed based on Rm symmetry (Supplementary Fig. The refined structural parameters of LNMO and LNRO are given in Supplementary Table 1, 2, respectively.
This difference was even more pronounced in the differential capacity (d Q/d V) plots (Fig. The charge profile of LNMO was characterized by a strong anodic peak at 4.55 V, corresponding to the extended voltage plateau, as well as two weak anodic peaks around 3.8 and 4.1 V.
In comparison, the strong anodic peak in the high-voltage region was absent in the charge profile of LNRO (Fig.
Rietveld refinement results suggest the as-produced LNMO and LNRO samples fit the structural model of monoclinic solid solution, though the nanocomposite concept concerning the mixture of layered Li Ni O (LNRO).
a Synchrotron XRD patterns, showing a similar crystal structure between these two compounds; XRD Rietveld refinement of b LNMO based on monoclinic C2/m and c LNRO based on monoclinic C2/c; d scanning electron microscopy (SEM) image of LNMO, the scale bar is 1 μm; e, f high-resolution transmission electron microscopy (HRTEM) images of LNMO with fast Fourier transform (FTT) of the selected area, the scale bar in (e) and (f) is 50 and 5 nm, respectively; g electron diffraction (ED) pattern for LNMO; h SEM image of LNRO, the scale bar is 1 μm; i, j HRTEM images of LNRO with FTT of the selected area, the scale bar in (i) and (j) is 100 and 2 nm, respectively; k ED pattern for LNROScanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) were used to further verify the morphology and crystal structure.
We first used operando DEMS to monitor any oxygen evolution stemming from the 2 O compensation reaction and quantify the irreversible loss of lattice oxygen as gaseous products, thus probe the extent of irreversibility of any oxygen participation in the charging process. 3) were collected at a current density of 10 m A g.