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Title: Two-dimensional lithium diffusion behavior and probable hybrid phase transformation kinetics in olivine lithium iron phosphate


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Hong, Liang, Li, Linsen, Chen-Wiegart, Yuchen-Karen, Wang, Jiajun, Xiang, Kai, Gan, Liyang, Li, Wenjie, Meng, Fei, Wang, Fan, Wang, Jun, Chiang, Yet-Ming, Jin, Song, and Tang, Ming. Two-dimensional lithium diffusion behavior and probable hybrid phase transformation kinetics in olivine lithium iron phosphate. United States: N. p., 2017. Web. doi:10.1038/s41467-017-01315-8.
Hong, Liang, Li, Linsen, Chen-Wiegart, Yuchen-Karen, Wang, Jiajun, Xiang, Kai, Gan, Liyang, Li, Wenjie, Meng, Fei, Wang, Fan, Wang, Jun, Chiang, Yet-Ming, Jin, Song, & Tang, Ming. Two-dimensional lithium diffusion behavior and probable hybrid phase transformation kinetics in olivine lithium iron phosphate. United States. doi:10.1038/s41467-017-01315-8.
Hong, Liang, Li, Linsen, Chen-Wiegart, Yuchen-Karen, Wang, Jiajun, Xiang, Kai, Gan, Liyang, Li, Wenjie, Meng, Fei, Wang, Fan, Wang, Jun, Chiang, Yet-Ming, Jin, Song, and Tang, Ming. 2017. "Two-dimensional lithium diffusion behavior and probable hybrid phase transformation kinetics in olivine lithium iron phosphate". United States. doi:10.1038/s41467-017-01315-8.
@article{osti_1406617,
title = {Two-dimensional lithium diffusion behavior and probable hybrid phase transformation kinetics in olivine lithium iron phosphate},
author = {Hong, Liang and Li, Linsen and Chen-Wiegart, Yuchen-Karen and Wang, Jiajun and Xiang, Kai and Gan, Liyang and Li, Wenjie and Meng, Fei and Wang, Fan and Wang, Jun and Chiang, Yet-Ming and Jin, Song and Tang, Ming},
abstractNote = {},
doi = {10.1038/s41467-017-01315-8},
journal = {Nature Communications},
number = 1,
volume = 8,
place = {United States},
year = 2017,
month =
}
  • Virtually all intercalation compounds used as battery electrodes exhibit significant changes in unit cell volume during use. Na xFePO 4 (0 < x < 1, NFP) olivine, of interest as a cathode for sodium-ion batteries, is a model for topotactic, high strain systems as it exhibits one of the largest discontinuous volume changes (~17% by volume) during its first-order transition between two otherwise isostructural phases. Using synchrotron radiation powder X-ray diffraction (PXD) and pair distribution function (PDF) analysis, we discover a new strain-accommodation mechanism wherein a third, <10 nm scale nanocrystalline phase forms to buffer the large lattice mismatch betweenmore » primary phases. The new phase has a and b lattice parameters matching one crystalline endmember phase and c lattice parameter matching the other, and is not detectable by powder diffraction alone. Finally, we suggest that this strain-accommodation mechanism may apply to systems with large transformation strains but in which true “amorphization” does not occur.« less
  • An objective in battery development for higher storage energy density is the design of compounds that can accommodate maximum ion concentration change over useful electrochemical windows. Not surprisingly, many storage compounds undergo phase transitions in-situ, including production of metastable phases. Unique to this environment is the frequent application of electrical over- and underpotentials, which are the electrical analogs to undercooling and superheating. Surprisingly, overpotential effects on phase stability and transformation mechanisms have not been studied in detail. Here we use synchrotron X-ray diffraction performed in-situ during potentiostatic and galvanostatic cycling, combined with phase-field modeling, to reveal a remarkable dependence ofmore » phase transition pathway on overpotential in the model olivine Li1-xFePO4. At both low (e.g., <20 mV) and high (>75 mV) overpotentials a crystal-to-crystal olivine transformation is preferred, whereas at intermediate overpotentials a crystalline-to-amorphous phase transition dominates. At nanoscale particle size, amorphization is further emphasized. Implications for battery use and design are considered.« less
  • Hybrid nanoparticles of LiFePO{sub 4} with carbon and lithium phosphates were synthesized through organic-inorganic co-assembly procedure using a triblock copolymer (F108 or P123). We found that the triblock copolymers play a critical role in controlling size of hybrid particle and the degree of crystallinity of the inorganic nanostructures. The hybrid using P-123 had more graphitic carbon which resulted in fast electron mobility. Also, magic angle spinning nuclear magnetic resonance (MAS-NMR) revealed that the crystallinity of the hybrid using P123 is higher than that using F108 which is not measurable in X-ray diffraction. Electrochemical performance of the hybrid using P123 asmore » a cathode material in Li-ion batteries showed superior rate capability at 20 C of charging rate and 2 C of discharging rate without capacity loss, in which discharge capacity was 102 mAh/g. - Graphical abstract: Hybrid nanoparticles were synthesized through organic-inorganic co-assembly based on synthetic procedure of mesoporous materials. P123-LFP showed superior high-rate capability at a 20 C charging rate and 2 C discharging rate without capacity loss in Li-ion battery. Highlights: Black-Right-Pointing-Pointer LiFePO{sub 4} nanohybrids are synthesized through the organic-inorganic co-assembly method. Black-Right-Pointing-Pointer Copolymers (F108 or P123) serve as structure directing agents and a carbon source. Black-Right-Pointing-Pointer P123 produces more graphitic carbon and higher crystalline nanohybrids. Black-Right-Pointing-Pointer Nanohybrids using P123 show superior rate capability in Li-ion battery.« less