Defect-Driven Configurational Entropy in the High-Entropy Oxide Li<sub>1.5</sub>MO<sub>3-δ</sub>.
basic_science · Level V
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- Record sourced from PubMed, PMID 38950351.
- Also identified by DOI 10.1021/acs.nanolett.4c00551.
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Abstract
Layered lithiated oxides are promising materials for next generation Li-ion battery cathode materials; however, instability during cycling results in poor performance over time compared to the high capacities theoretically possible with these materials. Here we report the characterizations of a Li<sub>1.47</sub>Mn<sub>0.57</sub>Al<sub>0.13</sub>Fe<sub>0.095</sub>Co<sub>0.105</sub>Ni<sub>0.095</sub>O<sub>2.49</sub> high-entropy layered oxide (HELO) with the Li<sub>2</sub>MO<sub>3</sub> structure where M = Mn, Al, Fe, Co, and Ni. Using electron microscopy and X-ray spectroscopy, we identify a homogeneous Li<sub>2</sub>MO<sub>3</sub> structure stabilized by the entropic contribution of oxygen vacancies. This defect-driven entropy would not be attainable in the LiMO<sub>2</sub> structure sometimes observed in similar materials as a secondary phase owing to the presence of fewer O sites and a 3+ oxidation state for the metal site; instead, a Li<sub>2-γ</sub>MO<sub>3-δ</sub> is produced. Beyond Li<sub>2</sub>MO<sub>3</sub>, this defect-driven entropy approach to stabilizing novel compositions and phases can be applied to a wide array of future cathode materials including spinel and rock salt structures.