Journal
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Volume 18, Issue 9, Pages 6893-6900Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/c5cp07182h
Keywords
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Funding
- National Research program of China [2013AA050901]
- Public projects of Zhejiang Province [2015C31122]
- Zhejiang Natural Science Foundation [LY16B030007]
- Ningbo Natural Science Foundation [2015A610240]
- Zhejiang Province Key Science and Technology Innovation Team [2013PT16]
- National Young scholar Natural Science Foundation of China [201303235]
- National Natural Science Foundation of China [11174301]
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Electrochemical cycling stabilities were compared for undoped and Al/Co dual-doped spinel LiMn2O4 synthesized by solid state reactions. We observed the suppression of particle fracture in Al/Co dual-doped LiMn2O4 during charge/discharge cycling and its distinguishable particle morphology with respect to the undoped material. Systematic first-principles calculations were performed on undoped, Al or Co single-doped, and Al/Co dual-doped LiMn2O4 to investigate their structural differences at the atomistic level. We reveal that while Jahn-Teller distortion associated with the Mn3+O6 octahedron is the origin of the lattice strain, the networking - i.e. the distribution of mixed valence Mn ions - is much more important to release the lattice strain, and thus to alleviating particle cracking. The calculations showed that the lattice mismatching between Li+ intercalation and deintercalation of LiMn2O4 can be significantly reduced by dual-doping, and therefore also the volumetric shrinkage during delithiation. This may account for the near disappearance of cracks on the surface of Al/Co-LiMn2O4 after 350 cycles, while some obvious cracks have developed in undoped LiMn2O4 at similar particle size even after 50 cycles. Correspondingly, Al/Co dual-doped LiMn2O4 showed a good cycling stability with a capacity retention of 84.1% after 350 cycles at a rate of 1C, 8% higher than the undoped phase.
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