Enhancing carrier transfer properties of Na-rich anti-perovskites, NaOM with tetrahedral anion groups: an evaluation through first-principles computational analysis
The practical application of Na-based solid-state electrolytes (SSEs) is limited by their low level of conduction. To evaluate the impact of tetrahedral anion groups on carrier migration, we designed a set of anti-perovskite SSEs theoretically based on the previously reported Na 4 OBr 2 , including...
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| Published in | Physical chemistry chemical physics : PCCP Vol. 26; no. 25; pp. 17934 - 17943 |
|---|---|
| Main Authors | , , , , |
| Format | Journal Article |
| Published |
26.06.2024
|
| Online Access | Get full text |
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| Summary: | The practical application of Na-based solid-state electrolytes (SSEs) is limited by their low level of conduction. To evaluate the impact of tetrahedral anion groups on carrier migration, we designed a set of anti-perovskite SSEs theoretically based on the previously reported Na
4
OBr
2
, including Na
4
O(BH
4
)
2
, Na
4
O(BF
4
)
2
, and Na
4
O(AlH
4
)
2
. It is essential to note that the excessive radius of anionic groups inevitably leads to lattice distortion, resulting in asymmetric migration paths and a limited improvement in carrier migration rate. Na
4
O(AlH
4
)
2
provides a clear example of where Na
+
migrates in two distinct environments. In addition, due to different spatial charge distributions, the interaction strength between anionic groups and Na
+
is different. Strong interactions can cause carriers to appear on a swing, leading to a decrease in conductivity. The low conductivity of Na
4
O(BF
4
)
2
is a typical example. This study demonstrates that Na
4
O(BH
4
)
2
exhibits remarkable mechanical and dynamic stability and shows ionic conductivity of 1.09 × 10
−4
S cm
−1
, two orders of magnitude higher than that of Na
4
OBr
2
. This is attributed to the expansion of the carrier migration channels by the anion groups, the moderate interaction between carriers and anionic groups, and the "paddle-wheel" effect generated by the anion groups, indicating that the "paddle-wheel" effect is still effective in low-dimensional anti-perovskite structures, in which atoms are arranged asymmetrically.
Sodium ions migrate through migration gates (MGs) in Na
4
O(BH
4
)
2
and cause rotation of the [BH
4
]
−
clusters that make up MGs. |
|---|---|
| ISSN: | 1463-9076 1463-9084 |
| DOI: | 10.1039/d3cp04162j |