Scalable Nitrate Treatment for Constructing Integrated Surface Structures to Mitigate Capacity Fading and Voltage Decay of Li‐Rich Layered Oxides

Abstract

Capacity fading and voltage decay is one of the biggest obstacles for the practical application of Li‐rich layered oxides due to the serious surface‐related detrimental reactions. Herein, we develop a versatile and scalable method to construct a robust surface‐integrated structure. All the designed samples deliver outstanding capacity and voltage stability, among which the Zn‐treated sample possesses the best electrochemical performance. Its capacity retention is larger than 90 % after 400 cycles with a voltage decay ratio as small as 0.73 mV per cycle. What is more, the rules of surface‐integrated structure with different cations in terms of capacity and voltage stability is further deciphered by combining with density function theory (DFT) calculations. It is found that to obtain advanced Li‐rich layered oxide cathodes, cations in Li‐sites should firstly ensure the binding energy of the surface‐integrated structure in a lower level and then provide Bader charge for the nearest O atoms as small as possible.

Facile Morphology Modulation to Enhance Stability and Fast Kinetics of Anionic Redox for Li-Rich Layered Oxides Cathodes

“…The peaks observed at 529.3, 531.3, and 532.5 eV correspond to lattice oxygen, oxygen vacancies, and surface deposits. , A comparison reveals that the R-LR materials exhibit fewer oxygen vacancies compared with the F-LR and S-LR materials. A suitable number of oxygen vacancies can lower the surface partial pressure, thereby suppressing oxygen release and enhancing electrical conductivity and Li + diffusion kinetics. ,− However, an excessive presence of oxygen vacancies can deteriorate the material’s structure and cyclic performance . Consequently, the structural stability of F-LR and S-LR materials might be inferior to that of R-LR materials due to the higher occurrence of oxygen defects during the synthesis process.…”

“…In Figure 3a, the XRD patterns of all three types of materials exhibit characteristic peaks corresponding to the typical layered rhombohedral structure of Li-Ni (1−x−y) Co x Mn y O 2 with R-3m space group as the main phase. 15,16 Some peaks located at 20.5−24.5°belong to the monoclinic Li 2 MnO 3 phase with the C2/m space group. 17 In addition, the (003)/(104) and (018)/(110) peaks confirm the excellent layered structure of all samples.…”

Enhancing the cycling stability of a hollow architecture Li-rich cathode via Ce-integrated surface/interface/doping engineering

“…3d, the peaks at 882.1, 888.9 and 898.1 eV and the peaks at 900.2, 907.0 and 916.2 eV are assigned to the Ce 3d 5/2 and Ce 3d 3/2 peaks of Ce 4+ ions, respectively. 34,35 The peaks at 885.4, 897.8 and 903.5 eV belong to Ce 3+ ions. The existence of Ce 4+ is due to the partial CeO 2 on the surface, which can be seen from XRD results (Fig.…”

Constructing a surface spinel layer to stabilize the oxygen frame of Li-rich layered oxides

“…17 This process reduces the migration energy barrier of transition metals, accompanied by the occurrence of the serious interface reaction. 18 They jointly drive the migration of the transition metal from the transition metal layer to lithium layer, which aggravates the structural evolution of the Li-rich cathode, 19 resulting in serious voltage and capacity attenuation. Therefore, stabilizing the oxygen frame to delay the structural evolution is critical to prepare advanced Li-rich layered oxide cathodes.…”