Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Room-temperature miscibility gap in LixFePO4

Nature Materials volume 5, pages 357–360 (2006)Cite this article

Abstract

The rechargeable lithium-ion cell is an advanced energy-storage system. However, high cost, safety hazards, and chemical instability prohibit its use in large-scale applications. An alternative cathode material, LiFePO4, solves these problems, but has a kinetic problem involving strong electron/hole localization1. One reason for this is believed to be the limited carrier density in the fixed monovalent Fe3+PO4/LiFe2+PO4 two-phase electrode reaction in LixFePO4. Here, we provide experimental evidence that LixFePO4, at room temperature, can be described as a mixture of the Fe3+/Fe2+ mixed-valent intermediate LiαFePO4 and Li1−βFePO4 phases. Using powder neutron diffraction, the site occupancy numbers for lithium in each phase were refined to be α=0.05 and 1−β=0.89. The corresponding solid solution ranges outside the miscibility gap (0<x<α,1−β<x<1) were detected by the anomaly in the configurational entropy, and also by the deviation of the open-circuit voltage from the constant equilibrium potential. These findings encourage further improvement of this important class of compounds at ambient temperatures.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Rietveld refinement pattern of the neutron diffraction data measured for Li0.5FePO4, at room temperature.
Figure 2: Calorimetric measurements for a 2032-type coin cell for charging and discharging processes.
Figure 3: Open-circuit voltage versus x in LixFePO4 at 25 ∘C.

Similar content being viewed by others

References

  1. Padhi, A. K., Nanjundaswamy, K. S. & Goodenough, J. B. Phospho-olivines as positive-electrode materials for rechargeable lithium batteries. J. Electrochem. Soc. 144, 1188–1194 (1997).

    Article  Google Scholar 

  2. Yamada, A. & Yamahira, T. Cathode for nonaqueous electrolyte lithium battery. European patent 1150368 (2001).

  3. Yamada, A., Chung, S.-C. & Hinokuma, K. Optimized LiFePO4 for lithium battery cathode. J. Electrochem. Soc. 148, A224–A229 (2001).

    Article  Google Scholar 

  4. Chung, S. Y., Bloking, J. T. & Chiang, Y. M. Electronically conductive phospho-olivines as lithium storage electrode. Nature Mater. 1, 123–128 (2002).

    Article  Google Scholar 

  5. Subramanya Herle, P., Ellis, B., Coombs, N. & Nazar, L. Nano-network electronic conduction in iron and nickel olivine phosphates. Nature Mater. 3, 147–152 (2004).

    Article  Google Scholar 

  6. Dahn, J. R. & McKinnon, W. R. Phase diagram of LixMo6Se8 for 0&lt;x&lt;1 from in situ x-ray studies. Phys. Rev. B 32, 3003–3005 (1985).

    Article  Google Scholar 

  7. Dahn, J. R. et al. Entropy of the intercalation compound LixMo6Se8 from calorimetry of electrochemical cells. Phys. Rev. B 32, 3316–3318 (1985).

    Article  Google Scholar 

  8. Delmas, C., Nadiri, A. & Soubeyroux, J. L. The NASICON-type titanium phosphates ATi2(PO4)3 (A=Li,Na) as electrode materials. Solid State Ionics 28–30, 419–423 (1988).

    Article  Google Scholar 

  9. Delacourt, C., Poizot, P., Tarascon, J. M. & Masquelier, C. The existence of a temperature-driven solid solution in LixFePO4 for 0&lt;x&lt;1 . Nature Mater. 4, 254–260 (2005).

    Article  Google Scholar 

  10. Andersson, A. S., Kalska, B., Häggström, L. & Thomas, J. O. Lithium extraction/insertion in LiFePO4: an X-ray diffraction and Mössbauer spectroscopy study. Solid State Ionics 130, 41–52 (2000).

    Article  Google Scholar 

  11. Yamada, A., Koizumi, H., Sonoyama, N. & Kanno, R. Phase change in LixFePO4 . Electrochem. Solid State Lett. 8, A409–A413 (2005).

    Article  Google Scholar 

  12. Kobayashi, Y. et al. Precise electrochemical calorimetry of LiCoO2/graphite lithium-ion cell—Understanding thermal behavior and estimation of degradation mechanism. J. Electrochem. Soc. 149, A978–A982 (2002).

    Article  Google Scholar 

  13. Kobayashi, Y. et al. Electrochemical and calorimetric approach to spinel lithium manganese oxide. J. Power Sources 81, 463–466 (1999).

    Article  Google Scholar 

  14. Reynier, Y. et al. Entropy of Li intercalation in LixCoO2 . Phys. Rev. B 70, 174304 (2004).

    Article  Google Scholar 

  15. Srinivasan, V. & Newman, J. Existence of path-dependence in the LiFePO4 electrode. Electrochem. Solid State Lett. 9, A110–A114 (2006).

    Article  Google Scholar 

  16. Morgan, D., Van der Ven, A. & Ceder, G. Li conductivity in LixMPO4 (M=Mn,Fe,Co,Ni) olivine materials. Electrochem. Solid State Lett. 7, A30–A32 (2004).

    Article  Google Scholar 

  17. Zhou, F., Marianetti, C. A., Cococcoini, M., Morgan, D. & Ceder, G. Phase separation in LixFePO4 induced by correlation effects. Phys. Rev. B 69, 201101 (2004).

    Article  Google Scholar 

  18. Yamada, A., Kudo, Y. & Liu, K. Y. Phase diagram of Lix(MnyFe1−y)PO4 (0&lt;x,y&lt;1) . J. Electrochem. Soc. 148, A1153–A1158 (2001).

    Article  Google Scholar 

  19. Yamada, A., Kudo, Y. & Liu, K. Y. Reaction mechanism of the olivine-type Lix(Mn0.6Fe0.4)PO4(0&lt;x&lt;1) . J. Electrochem. Soc. 148, A747–A754 (2001).

    Article  Google Scholar 

  20. Yamada, A. & Chung, S.-C. Crystal chemistry of the olivine-type Li(MnyFe1−y)PO4 and (MnyFe1−y) PO4 as possible 4 V cathode materials for lithium batteries. J. Electrochem. Soc. 148, A960–A967 (2001).

    Article  Google Scholar 

  21. Yamada, A. et al. Electrochemical, magnetic, and structural investigation of the Lix(MnyFe1−y)PO4 phases. Chem. Mater. 18, 804–813 (2006).

    Article  Google Scholar 

Download references

Acknowledgements

The authors would like to thank H. Miyashiro, S. Seki and Y. Ohno for enlightening discussions. This work was financially supported by the TEPCO Research Foundation, the Murata Science Foundation, Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, No. 16350108, and the New Energy and Industrial Technology Development Organization (NEDO).

Author information

Authors and Affiliations

  1. Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama, 226-8502, Japan

    Atsuo Yamada, Hiroshi Koizumi, Shin-ichi Nishimura, Noriyuki Sonoyama & Ryoji Kanno

  2. Institute of Applied Beam Science, Graduate School of Science and Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki, 316-8511, Japan

    Masao Yonemura

  3. Department of Electrical Engineering and Computer Sciences, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo, 671-2201, Japan

    Tatsuya Nakamura

  4. Central Research Institute of Electric Power Industry, 2-11-1 Iwadokita, Komae, Tokyo, 201-8511, Japan

    Yo Kobayashi

Authors
  1. Atsuo Yamada
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Hiroshi Koizumi
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Shin-ichi Nishimura
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Noriyuki Sonoyama
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Ryoji Kanno
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Masao Yonemura
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Tatsuya Nakamura
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Yo Kobayashi
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Atsuo Yamada.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary figures S1 - S4 and tables S1 - S2 (PDF 318 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Yamada, A., Koizumi, H., Nishimura, Si. et al. Room-temperature miscibility gap in LixFePO4. Nature Mater 5, 357–360 (2006). https://doi.org/10.1038/nmat1634

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat1634

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing