Elevating Energy Density for Sodium-Ion Batteries through Multielectron Reactions.
basic_science · Level V
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- Record sourced from PubMed, PMID 33621101.
- Also identified by DOI 10.1021/acs.nanolett.1c00100.
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Abstract
It remains a great challenge to explore desirable cathodes for sodium-ion batteries to satisfy the ever-increasing demand for large-scale energy storage systems. In this Letter, we report a NASICON-structured Na<sub>4</sub>MnCr(PO<sub>4</sub>)<sub>3</sub> cathode with high specific capacity and operation potential. The reversible access of the Mn<sup>2+</sup>/Mn<sup>3+</sup> (3.75/3.4 V), Mn<sup>3+</sup>/Mn<sup>4+</sup> (4.25/4.1 V), and Cr<sup>3+</sup>/Cr<sup>4+</sup> (4.4/4.3 V vs Na/Na<sup>+</sup>) redox couples in a Na<sub>4</sub>MnCr(PO<sub>4</sub>)<sub>3</sub> cathode endows a distinct three-electron redox reaction during the insertion/extraction process. The highly stable NASICON structure with a small volume variation upon cycling ensures long-time cycling stability (73.3% capacity retention after 500 cycles within the potential region of 2.5-4.6 V). The impedance analysis and interface characterization indicate that the evolution of a cathode electrolyte interphase at high potential is correlated with the capacity fading, while the robustness of the NASICON framework is redemonstrated.