Abstract
Spinel LiNi0.5Mn1.5O4 (LNMO) can adopt two crystallographic structures: an ordered P4332 structure and a disordered Fd3̅m structure. The disordered phase is associated with the reduction of a small amount of Mn4+ to Mn3+. LNMO single-crystals likely contain local regions of both ordered and disordered regions, which ensemble-averaged characterizations fail to distinguish. Herein, we employ high-spatial-resolution synchrotron X-ray nanodiffraction techniques to identify lattice distortions and structural defects in LNMO samples with octahedral and plate-like morphologies containing ∼6% and ∼22% of Mn3+, respectively. Differences in properties between the two particles give rise to different distributions of lattice variations, which may indicate differences in phase distributions. Bragg coherent diffraction is also used to observe phase heterogeneities in single grains. Lattice distortions and structural defects could shut down or open up local diffusion pathways for lithium ions, making lithium ion diffusion more complicated and potentially more tortuous than that in a perfect LNMO lattice.
Original language | English |
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Pages (from-to) | 690-695 |
Number of pages | 6 |
Journal | ACS Energy Letters |
Volume | 7 |
Issue number | 2 |
DOIs | |
State | Published - Feb 11 2022 |
Externally published | Yes |
Funding
The work was supported by the National Science Foundation under Grant No. DMR-1832613. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. This research used 3-ID of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. The authors acknowledge Dr. Chunguang Kuai for assistance with synchrotron XRD measurements and Dr. Chengjun Sun for assistance with XANES measurements.