Entropy and Electronic Structure Modulation of a Prussian Blue Analogue Cathode with Suppressed Phase Evolution for Potassium-Ion Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 39542854.
- Also identified by DOI 10.1021/acs.nanolett.4c04807.
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Abstract
Severe structural evolution and high content of [Fe(CN)<sub>6</sub>]<sup>4-</sup> defects drastically deteriorate K-ion storage performances of Prussian blue-based cathodes. Herein, a potassium manganese iron copper hexacyanoferrate (KFe<sub>2/3</sub>Mn<sub>1/6</sub>Cu<sub>1/6</sub>HCF), with suppressed anionic vacancies, eliminated band gap, and low K-ion diffusion barrier, is regarded as a cathode for potassium-ion batteries. The entropy stabilization effect and robust Cu-N bond induced by the inert Cu-ion with large electronegativity boost KFe<sub>2/3</sub>Mn<sub>1/6</sub>Cu<sub>1/6</sub>HCF to exhibit great phase state stability, thus inhibiting the structural transition of monoclinic ↔ cubic. Hence, KFe<sub>2/3</sub>Mn<sub>1/6</sub>Cu<sub>1/6</sub>HCF undergoes a zero-stress solid-solution reaction mechanism, where Fe and Mn serve as dual active sites for charge compensation. Consequently, KFe<sub>2/3</sub>Mn<sub>1/6</sub>Cu<sub>1/6</sub>HCF displays a high reversible capacity of 127.5 mAh·g<sup>-1</sup> with an energy density of 469.2 Wh·kg<sup>-1</sup> at 10 mA·g<sup>-1</sup> and superior cyclic stability with a high retention of 90.7% over 100 cycles. A high-energy-density K-ion full battery is assembled, contributing an ultralong lifetime over 1000 cycles with a low-capacity fading rate of 0.038% per cycle.