Purgatorio Agnese, Ducale Federico, Tensi Leonardo, Rocchigiani Luca, Leonardi Maurizio, Macchioni Alceo
Department of Chemistry, Biology and Biotechnology and CIRCC, University of Perugia, Via Elce di Sotto 8, Perugia 06123, Italy.
Italmatch Chemicals S.p.A., Via S. Tommaso, 13, Spoleto, PG 06049, Italy.
Inorg Chem. 2025 Sep 8;64(35):17754-17763. doi: 10.1021/acs.inorgchem.5c02111. Epub 2025 Aug 26.
The preparation of LiS-PS (LPS) solid electrolytes for all-solid-state lithium batteries through liquid-phase methods has attracted much attention over the last years. One of the most critical aspects to be clarified is how speciation affects the ionic conductivity of the synthesized materials, which is often lower than that obtained by other synthetic approaches. This paper shed some light on the species formed upon the reaction of LiS and PS in acetonitrile under mild conditions, exploring a wide range of LiS/PS molar ratios, by means of multinuclear/multidimensional NMR spectroscopy and single-crystal X-ray diffraction. Specifically, P NMR spectroscopy clearly evidenced the initial formation of PS (two triplets at 91.2 and 74.3 ppm, = 23.16 Hz) from the reaction of PS, solubilized likely via electrostatic interactions (singlet at 81.9 ppm), with LiS. On the way to the LPS solid electrolyte, the twisted (118.3 ppm) and chair (54.3 ppm) isomers of PS, as well as (PS) (86.5 ppm) and the solvent adduct [PS(CHCN)] (299.0 ppm), were intercepted. As for (PS), the observation of a sharp singlet in the P NMR spectrum and the evaluation by diffusion P NMR spectroscopy of a hydrodynamic volume of ca. 800 Å, substantially the same than that of PS, suggest the formation of a cyclic PS species. Consistently, also PS, potentially derived by the dissociation in two equal parts of PS, was observed in the P NMR spectrum as a singlet at 31.2 ppm. For all the investigated molar ratios, rather broad resonances in the -3.0/-1.5 ppm range were observed in the Li NMR spectra, reflecting the dynamic nature of these systems. Metathetic exchange of Li with the bis(triphenylphosphine)iminium cation was found to be a successful strategy to obtain good-quality single crystals of PS, chair and twisted PS, and PS, whose solid-state structures were determined by X-ray diffractometric studies.
近年来，通过液相法制备用于全固态锂电池的LiS-PS（LPS）固体电解质备受关注。其中一个亟待阐明的关键问题是物种形态如何影响合成材料的离子电导率，该电导率通常低于其他合成方法所获得的电导率。本文借助多核/多维核磁共振光谱和单晶X射线衍射，研究了在温和条件下LiS与PS在乙腈中反应生成的物种，考察了广泛的LiS/PS摩尔比。具体而言，³¹P NMR光谱清楚地证明了PS（可能通过静电相互作用溶解，在81.9 ppm处为单峰）与LiS反应最初生成了PS（在91.2和74.3 ppm处有两个三重峰，J = 23.16 Hz）。在形成LPS固体电解质的过程中，截获了PS的扭曲异构体（118.3 ppm）和椅式异构体（54.3 ppm），以及(PS)（86.5 ppm）和溶剂加合物[PS(CHCN)]（299.0 ppm）。对于(PS)，³¹P NMR光谱中尖锐单峰的出现以及扩散³¹P NMR光谱对约800 Å流体力学体积的评估（与PS基本相同）表明形成了环状PS物种。同样，在³¹P NMR光谱中也观察到了可能由PS解离成两个相等部分而产生的PS，在31.2 ppm处为单峰。对于所有研究的摩尔比，在Li NMR光谱中观察到-3.0/-1.5 ppm范围内相当宽的共振峰，反映了这些体系的动态性质。发现Li与双（三苯基膦）亚胺阳离子的复分解交换是获得高质量PS、椅式和扭曲PS以及(PS)单晶的成功策略，其固态结构通过X射线衍射研究确定。
