Synthesis and Performance of Disordered Positive Electrode Materials for Lithium Ion Batteries
This work explores these recent theories and looks to improve the design and understanding of disordered materials. Many elemental combination series are synthesized between x = 0.00 to 0.33 in Li1+xMy(1-x)N(1-y)(1-x)O2 using solid state synthesis methods with varying temperature and excess Li content to explore the role of synthesis in disordering. Choices for M and N include V, Ti, Mn, Fe, Mo, and Cr in order to investigate capacity relationships due to available redox and Li channels. Materials are characterized by X-Ray Diffraction (XRD), in-situ and ex-situ XRD, scanning electron microscopy, Mossbauer spectroscopy, induced coupled plasma optical emission spectroscopy and electrochemical testing. The structural and electrochemical data is compared with theoretical models based on available redox capacity and percolation theory.
Figure 1 shows that synthesis temperature plays an important role in the disordering process. Figure 2 demonstrates a series of Li1+xTiy(1-x)Fe(1-y)(1-x)O2 (0.00 ≤ x ≤ 0.25) heated at 800 °C. Electrochemical results were found to agree with current and proposed theories of disordered materials.
Discussion will include the importance of synthesis in disordered materials, as well as the performance of select series and how they compare to theoretical models.
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