Nonstoichiometry and Defects in Hydrothermally Synthesized ε-LiVOPO 4
- Binghamton Univ., NY (United States). NorthEast Center for Chemical Energy Storage; Binghamton Univ., NY (United States)
- Binghamton Univ., NY (United States). NorthEast Center for Chemical Energy Storage
- Binghamton Univ., NY (United States)
- Binghamton Univ., NY (United States). NorthEast Center for Chemical Energy Storage; Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
ε-LiVOPO4 has been synthesized through the hydrothermal method by adjusting the pH of the hydrothermal solution and the reaction temperature. This phase is formed between 180 and 220 °C, as diamond-like crystals around 10–15 μm in size. X-ray diffraction (XRD) analysis shows that hydrothermal ε-LiVOPO4 lattice parameters a and b linearly decrease, while c linearly increases when the synthesis temperature increases. Thermogravimetric analysis with mass spectroscopy reveals 1.5 to 0.5% water loss at about 350 °C for ε-LiVOPO4 synthesized at 180 and 220 °C, suggesting water or protons incorporation into the structure. Magnetic studies reveal ferrimagnetism in hydrothermal ε-LiVOPO4 below 10 K, as opposed to antiferromagnetic ordering below 14 K found in samples synthesized at high temperature. In-situ XRD upon heating of the hydrothermal ε-LiVOPO4 synthesized at 180, 200, and 220 °C reveals that the temperature dependences of their lattice parameters merge at about 500 °C; furthermore, at the same temperature the structure reversibly changes from triclinic to monoclinic. The lattice parameters and the magnetic properties of the hydrothermal samples heated to 750 °C are similar to those of solid-state synthesized ε-LiVOPO4. Based on structure and composition analysis, we suggest that hydrothermal samples can be described as an ε-Li1+xHyV1–zOPO4 (x, y, z < 0.1) solid solution. The electrochemical characterization of hydrothermal ε-LiVOPO4 reveals the first cycle capacity of about 300 mAh/g, which holds for about five cycles, gradually decreasing thereafter. The low-voltage region does not reveal voltage plateaus corresponding to Li1.5VOPO4 and Li1.75VOPO4 phases found in the solid-state material, further suggesting structural disorder in the low-temperature samples evidenced from the lattice parameters and the magnetic properties.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Northeastern Center for Chemical Energy Storage (NECCES); State Univ. of New York (SUNY), Albany, NY (United States); Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0001294; SC0012583; AC02-06CH11357
- OSTI ID:
- 1767481
- Alternate ID(s):
- OSTI ID: 1774618
- Journal Information:
- ACS Applied Energy Materials, Vol. 2, Issue 7; ISSN 2574-0962
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
energy storage (including batteries and capacitors)
defects
charge transport
materials and chemistry by design
synthesis (novel materials)
lithium-ion batteries
cathode
LiVOPO4
hydrothermal synthesis
chemical structure
physical and chemical processes
lattices
chemical synthesis
materials