Abstract
The structural evolution of Li2MoO3 during electrochemical delithiation/lithiation is reported. Li2MoO3 undergoes an irreversible crystalline to amorphous transformation which starts during the first delithiation step and gradually proceeds throughout subsequent cycles. This observation is supported by complementary data obtained from X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). The amorphization does not prevent reversible Li storage, and the Li2MoO3 cathodes exhibit initial capacities of 147 mAh/g (corresponding to 0.87 Li cycled per formula unit) at an average operating potential ∼2.5 V vs Li/Li+ with reasonably good cycling stability (81% capacity retention after 50 cycles). In-situ mass spectrometry studies reveal the amorphization of Li2MoO3 does not involve the release of oxygen gas even when charged to very positive potentials (i.e., 4.8 V vs Li/Li+). The Li storage properties and excellent oxidative stability of Li2MoO3 make it a promising candidate to improve the performance of traditional LiMO2 compounds in layered-layered composite cathodes with the general formula xLi2MoO3·(1 - x)LiMO2. Multiple synthesis routes were explored to prepare composites with x = 0.10-0.15, and their structure was characterized using XRD and time-of-flight neutron diffraction. Preliminary characterization of these materials shows that Li2MoO3 improves the cycling stability of an NMC cathode, presumably by mitigating detrimental structural rearrangement at high states of charge.
| Original language | English |
|---|---|
| Pages (from-to) | 5061-5068 |
| Number of pages | 8 |
| Journal | Chemistry of Materials |
| Volume | 30 |
| Issue number | 15 |
| DOIs | |
| State | Published - Aug 14 2018 |
Funding
This research is supported by the Assistant Secretary for 492 Energy Efficiency and Renewable Energy, Office of Vehicle 493 Technologies, of the U.S. Department of Energy (DOE) 494 through the Advanced Battery Materials Research (BMR) 495 Program. X-ray diffraction and scanning electron microscopy 496 were conducted at the Center for Nanophase Materials 497 Sciences, which is a DOE Office of Science User Facility. 498 Neutron diffraction at ORNL’s Spallation Neutron Source was 499 sponsored by the Scientific User Facilities Division, Office of 500 Basic Energy Sciences, DOE. Synchrotron measurements conducted in the F2 beamline, at Cornell High Energy Synchrotron Source (CHESS) are supported by the National Science Foundation and the National Institutes of Health/National Institute of General Medical Sciences under NSF award DMR−1332208. TEM work was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by DOE’s Office of Biological and Environmental Research and located at PNNL. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/ downloads/doe-public-access-plan).
| Funders | Funder number |
|---|---|
| National Institutes of Health/National Institute of General Medical Sciences | |
| Office of 500 Basic Energy Sciences | |
| Scientific User Facilities Division | |
| National Science Foundation | DMR−1332208 |
| U.S. Department of Energy | |
| Office of Energy Efficiency and Renewable Energy | |
| Vehicle Technologies Office |
