In an effort to better understand the intercalation mechanism of guest ions in polyanionic electrode materials, we employed a combincation of structural, spectroscopic and electrochemical characterization tools to study how the host structures respond to the (de)insertion of guest ions during charging and discharging of an battery cell. We did case studies on a low-cost silicate electrode, pyroxene-type LiFeSi2O6, and anti-NASICON Fe2(MoO4)3. Through high-resution neutron diffraction and Ritveld refinement, we found that the structural ridigity is related to the sluggish Li-ion diffusion in LiFeSi2O6. And with the help of in-situ XRD, neutron total scattering and symmetry mode analysis, we found out that the fast, highly reversible Li-ion intercalation is in concert with the polyhedra rotational distortion in Fe2(MoO4)3. Our results showed the close correlation between polyhdra rotational distortion and electrochemical properties in polyanionic intercalation electrodes and suggested strategies for designing higher performing electrode materials.

Effect of polyhedral rotational distortion on the electrochemical properties of polyanionic intercalation electrode materials

251st National Meeting (2016)

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