Effect of Lithium Deficiency on Lithium-Ion Battery Cathode Li_xNi_0.5Mn_1.5O₄

Abstract

We have investigated Li effects on the structural property change in Li x Ni 0.5 Mn 1.5 O 4 (LNMO, x = 1, 0.7, 0.5, 0.3, 0.1, 0) by using Rietveld refinement with neutron diffraction measurements. The polycrystalline LNMO samples were synthesized using the sol−gel process and were calcinated at 1000 °C for 10 h. It was found that all the structures of LNMO belong to the face-centered cubic spinel structure Fd3̅ m, irrespective of Li amount, and that there exists a small amount of the NiO secondary phase for x = 1. As lithium is extracted from LNMO, oxygen reduction also follows, and the amount of oxygen released (y) from the sample changes in the manner to keep both the amount and the oxidation state of Ni/Mn cations; the total chemical formula can be written as (Li x ) x+ (Ni 0.5 Mn 1.5 ) 6.25+ (O 4−y ) −(6.25+x) for x ≤ 0.7 and LiNi 0.5−δ Mn 1.5 O 4−y−δ + δNiO with δ = 0.012 for x = 1. Both the lattice constant of a unit cell and the nearest neighbor bond distances of ions in LNMO continuously decrease with the increase of Li content, indicating that the variation of those parameters are much dependent on the strength of coulomb interactions between ions.

Low Interface Resistance in Solid-State Lithium Batteries Using Spinel LiNi0.5Mn1.5O4(111) Epitaxial Thin Films

“…This decrease in the cubic lattice constant is caused by the deposition of the LPO film. Recent work has reported that the lattice constant of LNMO bulk polycrystals decreases as the content of Li increases . The lattice constant of the LNMO(111) epitaxial thin film without LPO is close to the 8.238 Å value of a LNMO crystal with 30% Li deficiency, and the lattice constant of the LNMO(111) epitaxial thin film with LPO agrees with the lattice constant of 8.178 Å of a LNMO crystal without Li deficiency.…”

“…Recent work has reported that the lattice constant of LNMO bulk polycrystals decreases as the content of Li increases. 17 fringe around Bragg peaks in LNMO(111) epitaxial thin film with LPO is attributed to higher crystallinity as a result of the compensation of Li deficiency. These results indicate that the loss of Li content during the growth of LNMO would be compensated by the deposition of LPO even before a battery operation.…”

Statistical Multiobjective Optimization of Thiospinel CoNi2S4 Nanocrystal Synthesis via Design of Experiments

“…Rietveld refinement of powder XRD data was used to confirm that the nanocrystals synthesized under this set of optimal conditions possessed the desired Fd m thiospinel structure ( a = 9.413(3) Å, Figure d), with an average composition of CoNi 2.7 S 3.3 as determined by SEM–EDX. Although the empirical formula is off-stoichiometry, there is sufficient evidence in the literature demonstrating the presence of nonstoichiometry in thiospinel structures. ,,− In addition, high-resolution TEM images of the resulting nanocrystals possess lattice fringes consistent with the {400} and {220} lattice planes of the CoNi 2 S 4 thiospinel structure ( d = 0.24 and 0.33 nm, respectively, Figure S4).…”

Temperature-dependent oxygen behavior of LixNi0.5Mn1.5O4 cathode material for lithium battery

“…34,35 Previously we characterized the structural properties of Li from the neutron diffraction measurements. 36 And one of the results showed that, with the extraction of Li from LNMO, the amount of oxygen decreased in such a way that both the amount and the oxidation state of Ni and Mn cations are taken into account. These phenomena of oxygen and cation behavior at 30 • C motivated us to investigate the oxygen behavior and crystal structures in the wide temperature range from room temperature to 1000 • C with the variation of Li in LNMO.…”