Fluid-enhanced surface diffusion controls intraparticle phase transformations

Yiyang Li, Hungru Chen, Kipil Lim, Haitao D. Deng, Jongwoo Lim, Dimitrios Fraggedakis, Peter M. Attia, Sang Chul Lee, Norman Jin, Jože Moškon, Zixuan Guan, William E. Gent, Jihyun Hong, Young Sang Yu, Miran Gaberšček, M. Saiful Islam, Martin Z. Bazant, William C. Chueh

Research output: Contribution to journalArticlepeer-review

100 Citations (SciVal)


Phase transformations driven by compositional change require mass flux across a phase boundary. In some anisotropic solids, however, the phase boundary moves along a non-conductive crystallographic direction. One such material is LiXFePO4, an electrode for lithium-ion batteries. With poor bulk ionic transport along the direction of phase separation, it is unclear how lithium migrates during phase transformations. Here, we show that lithium migrates along the solid/liquid interface without leaving the particle, whereby charge carriers do not cross the double layer. X-ray diffraction and microscopy experiments as well as ab initio molecular dynamics simulations show that organic solvent and water molecules promote this surface ion diffusion, effectively rendering LiXFePO4 a three-dimensional lithium-ion conductor. Phase-field simulations capture the effects of surface diffusion on phase transformation. Lowering surface diffusivity is crucial towards supressing phase separation. This work establishes fluid-enhanced surface diffusion as a key dial for tuning phase transformation in anisotropic solids.

Original languageEnglish
Pages (from-to)915-922
Number of pages8
JournalNature Materials
Issue number10
Early online date17 Sept 2018
Publication statusPublished - 31 Oct 2018

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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