Triggering dynamically disordered lithium sublattice in superionic conductors.
basic_science · Level V
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- Record sourced from PubMed, PMID 41917061.
- Also identified by DOI 10.1038/s41467-026-71304-3.
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Abstract
The design of superionic conductors has been largely focused on static structural features, with the dynamic ion transport mechanism less explored. Here, we explore a paradigm that harnesses the polyanion rotations to trigger the dynamically disordered Li sublattice as well as the liquid-like cation diffusion for superior ionic conductivity in crystals. A descriptor called rotation tolerance factor was proposed as a predictive metric for identifying the potential fast-rotating anion clusters with the low mass and reduced valence charge for given structural frameworks. Guided by this factor, halides with rotational polyanions, namely Li<sub>3</sub>Y(SH)<sub>6</sub>, Li<sub>3</sub>Y(NH<sub>2</sub>)<sub>6</sub>, Li<sub>2</sub>Zr(NH<sub>2</sub>)<sub>6</sub>, and an oxide (Li<sub>6.5</sub>La<sub>3</sub>Zr<sub>2</sub>O<sub>11.5</sub>(NH<sub>2</sub>)<sub>0.5</sub>) have been designed with synergistic polyanion rotation and Li⁺ sublattice disorder, which lead to enhanced Li ionic conductivities at room temperature compared to the counterparts without polyanions. The experimentally synthesized NH<sub>2</sub><sup>-</sup> incorporated Li<sub>2</sub>ZrCl<sub>5.92</sub>(NH<sub>2</sub>)<sub>0.08</sub> demonstrates a four-fold higher conductivity over Li<sub>2</sub>ZrCl<sub>6</sub> control, enabling all-solid-state Li-In | |LiCoO<sub>2</sub> and Li-In | |LiNi<sub>0.88</sub>Co<sub>0.09</sub>Mn<sub>0.03</sub>O<sub>2</sub> cells with 96.5% and 97.4% capacity retention after 190 cycles at 140 and 200 mA g<sup>-1</sup>, respectively. This work provides an insight that flexible anion rotations could promote the dynamically disordered lithium sublattice distribution as well as the ionic conductivity.