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3727658 
Journal Article 
Spinel LiMn2O4 Crystal Structure and Lithium Ion-Sieve Property of H+/Li+ Exchange 
Liu Xiao-Li; Yang Li-Xin; Wu Sai-Xiang; Li Fen 
2012 
Yes 
Chinese Journal of Inorganic Chemistry / Wu Ji Hua Xue Xue Bao
ISSN: 1001-4861 
28 
8 
1673-1679 
WOS:000309152900022 
The crystal structures and properties of spinel-type LiMn2O4 and lithium ion-sieve HMn2O4 were investigated by using the plane-wave ultrasoft pseudopotential and the generalized gradient approximation based on density functional theory. The PW91 functional was the most beneficial. HMn2O4 unit cell contracted after Li+ was substituted by H+, the lattice constant decreased to 0.799 nm from 0.823 nm of LiMn2O4, and the XRD peaks also obviously shifted toward high angle correspondingly. According to the XRD analyses of homologous lattice atoms, we concluded that two elements Mn and 0 play a decisive role in the XRD mode and intensity. Among them, Li presents +1 valence and is completely ionized, and can be exchanged by H+ thoroughly; while H displays the mutual connections of electron clouds with ambient 0 in the isoelectronic density map, and only takes 0.42 positive charge. Atomic partial densities of states show that the strong covalent bonding between Mn-O is mainly attributed to the orbital overlap of Mn-d and O-p between -7.3 similar to-1.6 eV below the Fermi level, and forms the hole tunnels of framework that are beneficial to ion exchange. The volumes of lattice point and hole polyhedrons comply with the following sequences: V-8a>V-48f>V-8b, V16cV16d, V-16c>V-48f. Li+ is most apt to migrate to an adjacent 16c position, and alkali metal ion exchanges are subjected to the limitation of ionic radius and the size of acting energy. 
LiMn2O4; XRD calculation; partial density of state; electronic population; ion-sieve