Cation ordered Ni-rich layered cathode for ultra-long battery life

Abstract

Fluorine doping of a compositionally graded cathode, with an average concentration of Li[Ni0.80Co0.05Mn0.15]O2, yields a high discharge capacity of 216 mAhg–1 with unprecedented cycling stability by retaining 78% of its...

Comprehensive Study of Li+/Ni2+ Disorder in Ni-Rich NMCs Cathodes for Li-Ion Batteries

“…The [010] and [110] HAADF-STEM images, in which the Li and TM slabs can be easily distinguished, were interpreted visually, sometimes supporting the conclusions by plotting the intensity profiles. The local structure of the disordered regions was analyzed by estimation of the brightness of the dots, associated with Ni ions migrated to Li slabs, and followed by tentative assignment of the local areas to layered, spinel, or rock-salt structure types [15,[27][28][29][30][31]. The development of state-of-the-art techniques, aimed at the quantitative analysis of high-resolution STEM images, based on the application of statistical parameter estimation theory [33,[52][53][54], makes it possible to directly quantify the number of atoms in each projected atomic column in the HAADF-STEM image.…”

“…Transmission electron microscopy (TEM) is an alternative approach, very suitable for local area analysis [27]. High-resolution high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and annular brightfield STEM (ABF-STEM) imaging techniques are widely used to obtain the local structural information, but in most cases in a rather empirical and less quantitative manner [15,[28][29][30][31]. Nevertheless, the tools based on statistical parameter estimation approaches for retrieving local crystallographic information from the TEM images are already available and can be potentially applied to measuring the cationic disorder in Ni-rich NMCs at an atomic scale [32,33].…”

A Review of Degradation Mechanisms and Recent Achievements for Ni‐Rich Cathode‐Based Li‐Ion Batteries

“…[ 143 ] Most recently, Sun's group investigated the origin of the ultralong cycle life of F − ‐doped NCM cathode materials from an atomic point of view. [ 134 ] This study reveals F − ‐doped NCM materials will induce the formation of an ordered structure with 2 a hex × 2 a hex × c hex superlattice. As shown in Figure 24c, Ni migration at the Li‐sites occurs every two rows to form this superlattice structure.…”

“…Up to now, numerous substitutional elements have been proposed, such as Mg, Zr, Ce, Mo, Ta, etc., as cation dopant and F, Br, etc., as anion dopant. [ 129–135 ] Table 2 summarizes the most important dopants for Ni‐rich cathodes that have been published in the last three years.…”

Why is the O3 to O1 phase transition hindered in LiNiO2 on full delithiation?

“…Note that such unfavorable Ni ion migration to tetrahedral sites is effectively suppressed by substitution of Ni ions by other metal ions, leading to the improvement of electrode reversibility in the high-voltage region, which will be reported in detail elsewhere. Although stoichiometric layered materials, like LiNiO 2 derivatives, show excellent capacity retention as electrode materials, 22,23 now the experimentally available reversible capacity is approaching its theoretical limit. To further increase reversible capacities, Li-enrichment in the host structure is necessary.…”