Lattice‐Cell Orientation Disorder in Complex Spinel Oxides

Abstract

Transition metal (TM) substitution has been widely applied to change complex oxides crystal structures to create high energy density electrodes materials in high performance rechargeable lithium-ion batteries. The complex local structure in the oxides imparted by the TM arrangement often impacts their electrochemical behaviors by influencing the diffusion and intercalation of lithium. Here, a major discrepancy is demonstrated between the global and local structures of the promising high energy density and high voltage LiNi 0.5 Mn 1.5 O 4 spinel cathode material that contradicts the existing structural models. A new single-phase lattice-cell orientation disorder model is proposed as the mechanism for the local ordering that explains how the inhomogeneous local distortions and the coherent connection give rise to the global structure in the complex oxide. Further, the single-phase model is consistent with the electrochemical behavior observation of the materials.

Effectively enhanced structural stability and electrochemical properties of LiNi0.5Mn1.5O4cathode materialsviapoly-(3,4-ethylenedioxythiophene)-in situcoated for high voltage Li-ion batteries

“…S1, † (111) peak for pristine LNMO shis slightly to the high 2-theta, indicated that the decrease of intensity and lattice parameter of the LiNi 0.5 Mn 1.5 O 4 electrode without PEDOT. [47][48][49][50] But there is no evident of diffraction peaks shi of the cycled LNMO electrode with PEDOT coating. The diffraction peak shi for the electrode cycled in pristine LNMO is most likely caused by the dissolution of Mn 3+ from the bulk structure, which leads to generate the smaller radius of Mn 4+ via the disproportionation reaction.…”

Enhancing the Ion Transport in LiMn1.5Ni0.5O4 by Altering the Particle Wulff Shape via Anisotropic Surface Segregation

“…[53][54][55][56] For long term annealing at 700 °C, LiMn 1.5 Ni 0.5 O 4 intended to become ordered structure, and the ordered structure is disturbed upon further higher heating. 57,58 While these samples were annealed at 800 °C and cooled down quickly, both of them retained the fully disordered structure. Both patterns of undoped and doped specimens did not show any superstructure peaks arising from ordered structure (P4 3 32 space group) and both were successfully refined according to the Fd 3 m space group of a disordered structure; the corresponding reliable factors R wp and R p are 3.76% and 2.89 % for the undoped specimen, and they were 3.36% and 2.47% for the doped specimen.…”

Tracing Phase Transformation and Lattice Evolution in a TRIP Sheet Steel under High-Temperature Annealing by Real-Time In Situ Neutron Diffraction

“…The large cross-section of all components in the material make it possible to differentiate mixed phases and to monitor the phase evolutions under the external stimuli [33][34][35][36]. The static neutron incident slits and detectors of the TOF diffractometer ensure the high resolution to precisely resolve the lattice parameters/strains [37,38]. The average structure information given from a bulk provide statistical quantities such as phase fraction [39], preferential orientation [40], lattice site occupancy [41,42] and their evolutions [43,44].…”