P2-Type Moisture-Stable and High-Voltage-Tolerable Cathodes for High-Energy and Long-Life Sodium-Ion Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 36811529.
- Also identified by DOI 10.1021/acs.nanolett.2c04465.
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Abstract
P2-Na<sub>0.67</sub>Ni<sub>0.33</sub>Mn<sub>0.67</sub>O<sub>2</sub> represents a promising cathode for Na-ion batteries, but it suffers from severe structural degradation upon storing in a humid atmosphere and cycling at a high cutoff voltage. Here we propose an in situ construction to achieve simultaneous material synthesis and Mg/Sn cosubstitution of Na<sub>0.67</sub>Ni<sub>0.33</sub>Mn<sub>0.67</sub>O<sub>2</sub> via one-pot solid-state sintering. The materials exhibit superior structural reversibility and moisture insensitivity. In-operando XRD reveals an essential correlation between cycling stability and phase reversibility, whereas Mg substitution suppressed the P2-O2 phase transition by forming a new Z phase, and Mg/Sn cosubstitution enhanced the P2-Z transition reversibility benefiting from strong Sn-O bonds. DFT calculations disclosed high chemical tolerance to moisture, as the adsorption energy to H<sub>2</sub>O was lower than that of the pure Na<sub>0.67</sub>Ni<sub>0.33</sub>Mn<sub>0.67</sub>O<sub>2</sub>. A representative Na<sub>0.67</sub>Ni<sub>0.23</sub>Mg<sub>0.1</sub>Mn<sub>0.65</sub>Sn<sub>0.02</sub>O<sub>2</sub> cathode exhibits high reversible capacities of 123 mAh g<sup>-1</sup> (10 mA g<sup>-1</sup>), 110 mAh g<sup>-1</sup> (200 mA g<sup>-1</sup>), and 100 mAh g<sup>-1</sup> (500 mA g<sup>-1</sup>) and a high capacity retention of 80% (500 mA g<sup>-1</sup>, 500 cycles).