Figure shows the synthesis process of 811@MoO3 and 811@Al2O3. After PEALD cycle, the artificial CEI layer of MoO3 and Al2O3 are synthesized on the surface of 811 electrode. Figure is the SEM image of 811@MoO3. The TEM samples were prepared by FIB cutting, as shown in Figure . Based on the data obtained, few crystalline phases were detected in the 811@MoO3 layer, possibly due to the formation of MoO3 amorphous structure on the NMC811. d-spacing of the crystalline planes was estimated via the distance between the bright spots in the SAED pattern. In Figure , the (101) and (311) lattice of MoO3 can be identified in the SAED of 811@MoO3. Figure is the SEM-EDS mapping of 811@MoO3. The thickness of MoO3 layer is about 1 μm. Figure and 2f are the SEM and TEM images of 811@Al2O3, respectively. The Al2O3 layer was uniformly deposited after 200 cycles on the NMC811 electrode surface. As can be seen, a thinner layer with a more uniform structure was formed in theasl2O3 coating compared with that in the MoO3 protective layer. This could be attributed to the point that Al2O3 is a more compact substance than MoO3, so a thinner layer of Al2O3 could provide the same level of protection as a thicker layer of MoO3. In Figure , the SAED pattern shows the (113) lattice plane of Al2O3, the diffraction ring indicates the Al2O3 is near amorphous. The creation of an amorphous Al2O3 layer on the NMC811 surface is accounted for a great condition for providing rapid Li + ion diffusion. Figure is the SEM-EDS mapping of 811@Al2O3. The thickness of Al2O3 layer is about 1 μm. EDS was also conducted on the NMC811, NMC@Al2O3, and NMC@MoO3 samples, which is shown in Figure . As shown in Figure , the MoO3 and Al2O3 are uniformly deposited on the 811 electrodes. With reference to the EDX spectrum of the 811 (Figure ), Mo and Al Kα signals were appeared in the 811@MoO3 (Figure ) and 811@Al2O3 (Figure ) samples, which confirm the successful of PEALD coatings. The XRD spectra were obtained to evaluate the crystal structure of the NMC811 before and after the coating procedure. As could be seen in Figure , NMC811 powder showed diffraction peaks at 18.68 (003), 36.62 (101), 37.96 (006), 38.28 (012), 44.40 (104), 48.60 (015), 58.66 (107), 64.42 (018), 64.86 (110), and 68. 16 (113). The spectrum of 811@MoO3 and 811@Al2O3 shows similar peaks with NMC, indicates after ALD coating MoO3 and Al2O3, the main crystal structure of NMC is maintained. Besides, there are no obvious peaks of MoO3 and Al2O3, this might be due to the coating layer is very thin and it is nearly amorphous structure.