Electrical transport properties in LiMn2O4, Li0.95Mn2O4, and LiMn1.95B0.05O4 (B=Al or Ga) around room temperature

Abstract

Low temperature dielectric properties of YMn 0.95 Ru 0.05 O 3 AIP Conf. Correlation between high ionic conductivity and twin structure of La 0.95 Sr 0.05 Ga 0.9 Mg 0.1 O 3 − δ Nature of small-polaron hopping conduction and the effect of Cr doping on the transport properties of rare-earth manganite La 0.5 Pb 0.5 Mn 1−x Cr x O 3In order to identify the carrier responsible for the electrical transport at room temperature in LiMn 2 O 4 from the viewpoint of practical applications as a cathode material, the bulk conductivity measurements by complex-plane impedance analyses have been carried out on LiMn 2 O 4 , Li 0.95 Mn 2 O 4 , and LiMn 1.95 B 0.05 O 4 ͑BϭAl 3ϩ or Ga 3ϩ ͒ together with the measurements of four-probe dc conductivities and dielectric relaxation processes, because these are two candidates for the carrier, a Li ion or a nonadiabatic small polaron of an e g electron on Mn 3ϩ . The comparison of the ionic conductivity estimated numerically from the parameters obtained experimentally for the Li-diffusion in LiMn 2 O 4 with the bulk conductivity indicates that the Li-diffusion seems difficult to play the primary role in the electrical conduction. Instead, a hopping-process of nonadiabatic small polarons of e g electrons is likely to dominate predominantly the electrical transport properties. The dielectric relaxation process, and the activation energies and the pre-exponential factors of the bulk conductivities in Li 0.95 Mn 2 O 4 and LiMn 1.95 B 0.05 O 4 are explained self-consistently in terms of the polaronic conduction.

A.C conductivity and dielectric properties of spinel LiMn2O4 nanorods

“…Hence, it is concluded that the conductivity in spinel LiMn 2 O 4 nanorods is mainly due to electrical conduction in grains. The observed activation energy for spinel LiMn 2 O 4 nanorods is comparable to the reported values (0.39 eV,0.38 eV, 0.42 eV)[37,41,42].…”

Electronic and Electrochemical Properties of Li1–xMn1.5Ni0.5O4 Spinel Cathodes As a Function of Lithium Content and Cation Ordering

“…Charge transport is expected to take place in the form of incoherent motion via adiabatic small-polaron hopping between eg orbitals of the Ni ions; this mechanism is characteristic of many oxides, and has been evidenced in LiMn2O4. [29][30][31][32][33] A small polaron manifests in an ionic solid as a point charge accompanied by a local distortion of the ions around that charge. 34,35 This distortion creates a selftrapping effect in which the charge carrier is at the bottom of a potential well created by its presence through electron-phonon coupling.…”

Electrochemical strain microscopy time spectroscopy: Model and experiment on LiMn2O4

“…However, the lock-in detection system of the microscope can measure other AC-mediated responses as explained in Section I. Taking into account that LiMn 2 O 4 is a small polaron semiconductor, 27 an additional contribution can emerge from AC mediated dipoles. Chen et al 35 suggested that voltage spectroscopy hysteresis loops can be used to distinguish between polar and non-polar contributions.…”

“…1, [26][27][28] It was theoretically shown that the polaron hopping can impact lithium ion movements 28 and experimentally deduced that lithium diffusivity is intrinsically related to the polaronic properties. 29 As this coupling is little understood and it is hard to quantify, it will be reserved to future studies.…”