Abstract
Microwave heating presents a faster, lower energy synthetic methodology for the realization of functional materials. Here, we demonstrate for the first time that employing this method also leads to a decrease in the occurrence of defects in olivine structured LiFe1-xMnxPO4. For example, the presence of antisite defects in this structure precludes Li+ diffusion along the b-axis leading to a significant decrease in reversible capacities. Total scattering measurements, in combination with Li+ diffusion studies using muon spin relaxation (μ+SR) spectroscopy, reveal that this synthetic method generates fewer defects in the nanostructures compared to traditional solvothermal routes. Our interest in developing these routes to mixed-metal phosphate LiFe1-xMnxPO4 olivines is due to the higher Mn2+/3+ redox potential in comparison to the Fe2+/3+ pair. Here, single-phase LiFe1-xMnxPO4 (x = 0, 0.25, 0.5, 0.75 and 1) olivines have been prepared following a microwave-assisted approach which allows for up to 4 times faster reaction times compared to traditional solvothermal methods. Interestingly, the resulting particle morphology is dependent on the Mn content. We also examine their electrochemical performance as active electrodes in Li-ion batteries. These results present microwave routes as highly attractive for reproducible, gram-scale syntheses of high quality nanostructured electrodes which display close to theoretical capacity for the full iron phase.
Original language | English |
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Pages (from-to) | 127-137 |
Number of pages | 11 |
Journal | Journal of Materials Chemistry A |
Volume | 6 |
Issue number | 1 |
DOIs | |
State | Published - 2017 |
Externally published | Yes |
Funding
The authors gratefully acknowledge STFC for the allocation of beamtime at the Polaris and EMU beamlines at the ISIS Neutron and Muon Source. We are extremely grateful to Mr Michael Beglan at the School of Chemistry at the University of Glasgow for technical support. We thank Mr Peter Chung (School of Geographical and Earth Sciences, University of Glasgow) for his valuable assistance with SEM measurements. We thank Dr Donald MacLaren of the MCMP group at the University of Glasgow for helpful discussion of the (S)TEM data acquisition and analysis. This work was supported by funding from the EPSRC (EP/N001982/1) and we thank the School of Chemistry at the University of Glasgow for support, the Kelvin Nano-characterisation Centre and the School of Chemistry for use of facilities. Work in the Billinge group was supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences (DOE-BES) under contract No. DE-SC00112704.
Funders | Funder number |
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DOE-BES | DE-SC00112704 |
Kelvin Nano-characterisation Centre | |
U.S. Department of Energy | |
Office of Science | |
Basic Energy Sciences | |
Engineering and Physical Sciences Research Council | EP/N001982/1 |