Dopant Segregation Boosting High-Voltage Cyclability of Layered Cathode for Sodium Ion Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 31583768.
- Also identified by DOI 10.1002/adma.201904816.
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Abstract
As a widely used approach to modify a material's bulk properties, doping can effectively improve electrochemical properties and structural stability of various cathodes for rechargeable batteries, which usually empirically favors a uniform distribution of dopants. It is reported that dopant aggregation effectively boosts the cyclability of a Mg-doped P2-type layered cathode (Na<sub>0.67</sub> Ni<sub>0.33</sub> Mn<sub>0.67</sub> O<sub>2</sub> ). Experimental characterization and calculation consistently reveal that randomly distributed Mg dopants tend to segregate into the Na-layer during high-voltage cycling, leading to the formation of high-density precipitates. Intriguingly, such Mg-enriched precipitates, acting as 3D network pillars, can further enhance a material's mechanical strength, suppress cracking, and consequently benefit cyclability. This work not only deepens the understanding on dopant evolution but also offers a conceptually new approach by utilizing precipitation strengthening design to counter cracking related degradation and improve high-voltage cyclability of layered cathodes.