Crystal Structure and Bond-Valence Investigation of Nitrogen-Stabilized LiAl5O8 Spinels

An in-depth insight into the effect of nitrogen substitution on structural stabilization is important for the design of new spinel-type oxynitride materials with tailored properties. In this work, the crystal structures of ordered and disordered LiAl₅O₈ obtained by slow cooling and rapid quenching, respectively, were analyzed by a X-ray diffraction (XRD) Rietveld refinement and OccQP program. The variation in the bonding state of atoms in the two compounds was explored by the bond valence model, which revealed that the instability of spinel-type LiAl₅O₈ crystal structure at room temperature is mainly due to the severe under-bonding of the tetrahedrally coordinated Al cations. With the partial substitution of oxygen with nitrogen in LiAl₅O₈, a series of the nitrogen-stabilized spinel Li_yAl_(16+x-y)/3O_8-xN_x (0 < x < 0.5, 0 < y < 1) was successfully prepared. The crystal structures were systematically investigated by the powder XRD structural refinement combined with ⁷Li and ²⁷Al magic-angle spinning nuclear magnetic resonance. All the Li⁺ ions entered the octahedra, while the Al resonances may be composed of multiple non-equivalent Al sites. The structural stability of spinel Li_yAl_(16+x-y)/3O_8-xN_x at ambient temperature was attributed to the cationic vacancies and high valence generated by the N ions, which alleviated the under-bonding state of the tetrahedral Al-O bond. This work provides a new perspective for understanding the composition-structure relationship in spinel compounds with multiple disorders.

Structural, morphological, and electrical properties of silver-substituted ZnAl2O4 nanoparticles

In this paper, nanoparticles of (x = 0.05 and x = 0.1) were synthesized by the sol–gel auto-combustion method and characterized by various techniques.

Spinel MgAl2O4 modification on LiCoO2 cathode materials with the combined advantages of MgO and Al2O3 modifications for high-voltage lithium-ion batteries

In order to improve the electrochemical performance of LiCoO₂ cathode in a high-voltage range of 3.0–4.5 V, spinel MgAl₂O₄ has been modified on the surface of LiCoO₂ particle by a facile high-temperature solid state reaction.

Structural limitations for optimizing garnet-type solid electrolytes: a perspective

Lithium ion batteries exhibit the highest energy densities of all battery types and are therefore an important technology for energy storage in every day life. Today's commercially available batteries employ organic polymer lithium conducting electrolytes, leading to multiple challenges and safety issues such as poor chemical stability, leakage and flammability. The next generation lithium ion batteries, namely all solid-state batteries, can overcome these limitations through employing a ceramic Li(+) conducting electrolyte. In the past decade, there has been a major focus on the structural and ionic transport properties of lithium-conducting garnets, and the extensive research efforts have led to a thorough understanding of the structure-property relationships in this class of materials. However, further improvement seems difficult due to structural limitations. The purpose of this Perspective article is to provide a brief structural overview of Li conducting garnets and the structural influence on the optimization of Li-ionic conductivities.

Characterization of thin films of the solid electrolyte LixMg1−2xAl2+xO4 (x = 0, 0.05, 0.15, 0.25)

RF-sputtered thin films of spinel Li_xMg_1−2xAl_2+xO₄ were investigated for use as solid electrolyte in Li-ion batteries.