Jahn-Teller structural phase transition around 280K in LiMn2O4

Systematic Studies on “Abundant” Battery Materials: Identification and Reaction Mechanisms

“…The metal borate (LiMBO 3 ) family forms a special class of polyanionic cathodes with the lowest-weight polyanions (BO 3 ) 3¹ with a molecular weight of 58.8, which is significantly lighter than the larger tetrahedral (PO 4 ) 3¹ unit with a molecular weight of 95.0. A large theoretical capacity of 220 mAh/g is calculated based on the LiFeBO 3 chemical formula, which is much larger than the 170 mAh/g for LiFePO 4 . Furthermore, the true density of LiFeBO 3 is 3.46 g/cm 3 , which is close to that of LiFePO 4 and suitable for maximizing the volume energy density due to the minimum volume occupation of the planar triangle BO 3 oxyanion unit.…”

“…4). 4 In the lithium manganospinel system, LiMn 2 O 4 is of particular interest because it takes the threshold manganese valence, 3.5, where the cubic lattice is apt to exhibit JT distortion when the manganese valence is slightly reduced by lithium insertion 5 or oxygen extraction. 2 This situation led us to an investigation of the low temperature structure of LiMn 2 O 4 and the discovery of the unique Verwey-like chargeordering transition with large local JT distortion in the vicinity of T t = 280 K (Fig.…”

“…4,6,7 3. Olivine LiFePO 4 Defeating some negative perspectives raised at an early stage of the development, LiFePO 4 has been commercialized and received the common agreement of the battery community as most promising for the next generation lithium battery cathode. Operation under very high rate condition is possible, in spite of its insulating nature.…”

Diffusion of Li atoms in LiMn2O4 - A structural point of view -

“…is orthorhombic Fddd, a = 24.7550 (9), b = 24.8832 (9), c = 8.2003(3) Å, Z = 72. Numbers of crystallographically independent atom sites in a unit cell are 4 for Li (Li1-Li4 sites), 5 for Mn (Mn1-Mn5 sites) and 9 for O (O1-O9 sites).…”

Stress-induced charge-ordering process in LiMn2O4

“…[3][4][5] The cubic LMO lattice (Fd3m space group) has a single crystallographic Mn site, where the Mn ions have an average valence of +3.5. A structural transition accompanying the rearrangement of Mn 3+ and Mn 4+ occurs when the temperature is lowered to 280-290 K, [5][6][7][8][9] and it consequently leads to lowering of the lattice symmetry [10] due to the Jahn-Teller distortion of the MnO 6 octahedron with Mn 3+ that has one electron localized at the e g band, [11,12] as well as abrupt changes of conductivity, [13] magnetic property [5] and elastic constants. [14] Although similar to the Verway transition in Fe 3 O 4 , [15] the transition of LMO results in a complex charge-frustrated system, in contrast to the alternative charge-ordering configuration of Fe 3 O 4 .…”