High Entropy-Induced Kinetics Improvement and Phase Transition Suppression in K-Ion Battery Layered Cathodes.
basic_science · Level V
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- Record sourced from PubMed, PMID 38113246.
- Also identified by DOI 10.1021/acsnano.3c06393.
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Abstract
Layered oxides are widely accepted to be promising cathode candidate materials for K-ion batteries (KIBs) in terms of their rich raw materials and low price, while their further applications are restricted by sluggish kinetics and poor structural stability. Here, the high-entropy design concept is introduced into layered KIB cathodes to address the above issues, and an example of high-entropy layered K<sub>0.45</sub>Mn<sub>0.60</sub>Ni<sub>0.075</sub>Fe<sub>0.075</sub>Co<sub>0.075</sub>Ti<sub>0.10</sub>Cu<sub>0.05</sub>Mg<sub>0.025</sub>O<sub>2</sub> (HE-KMO) is successfully prepared. Benefiting from the high-entropy oxide with multielement doping, the developed HE-KMO exhibits half-metallic oxide features with a narrow bandgap of 0.19 eV. Increased entropy can also reduce the surface energy of the {010} active facets, resulting in about 2.6 times more exposure of the {010} active facets of HE-KMO than the low-entropy K<sub>0.45</sub>MnO<sub>2</sub> (KMO). Both can effectively improve the kinetics in terms of electron conduction and K<sup>+</sup> diffusion. Furthermore, high entropy can inhibit space charge ordering during K<sup>+</sup> (de)insertion, and the transition metal-oxygen covalent interaction of HE-KMO is also enhanced, leading to suppressed phase transition of HE-KMO in 1.5-4.2 V and better electrochemical stability of HE-KMO (average capacity drop of 0.20%, 200 cycles) than the low-entropy KMO (average capacity drop of 0.41%, 200 cycles) in the wide voltage window.