Kavli Affiliate: Kristin Persson
| First 5 Authors: Peichen Zhong, Peichen Zhong, , ,

| Summary:
Despite decades of study, the identity of the dominant ceLi+-conducting phase within the inorganic SEI of Li-ion batteries remains unresolved. While the mosaic model describes LiF/ceLi2O/ceLi2CO3 nanocrystallites within a disordered matrix, these crystalline phases inherently offer limited ionic conductivity. Growing evidence suggests that interfaces, grain boundaries, and amorphous phases may instead host the primary fast-ion pathways. Motivated by mixed-anion electrolyte decomposition products, we combine diffusion-based generative structure prediction with machine-learning interatomic potentials (MLIPs) to interrogate lithium difluorophosphate (ceLiPO2F2), a key decomposition product of phosphorus- and fluorine-containing electrolytes. We identify a stable crystalline polymorph and, through MLIP-accelerated molecular dynamics, show that the amorphous counterpart is more conductive, with projected room-temperature $σ$ $approx$ 0.18 mS cm$^-1$ and $E_mathrma$ $approx$ 0.40 eV. This enhancement is attributed to structural disorder, which flattens the Li site-energy landscape, and to a low formation energy for Li-interstitial defects, which supplies additional mobile carriers. We present mixed-anion, amorphous Li–P–O–F phases as promising candidates for the ceLi+-conducting medium of the inorganic SEI, offering a path forward for engineering improved battery interfaces.
| Search Query: arXiv Query: search_query=au:”Persson Kristin”&id_list=&start=0&max_results=3
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