Kuai Dacheng, Wang Shen, Perez-Beltran Saul, Yu Sicen, Real Gerard A, Liu Ping, Balbuena Perla B
Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States.
Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States.
ACS Energy Lett. 2024 Feb 5;9(3):810-818. doi: 10.1021/acsenergylett.3c02757. eCollection 2024 Mar 8.
Advances in sulfurized-polyacrylonitrile (SPAN)-based cathode materials promise safer and more efficient lithium-sulfur (Li-S) battery performance. To elucidate electrolyte-cathode interfacial electrochemistry and polysulfide (PS) dissolution, we emulate discharge SPAN reactions via molecular dynamics (AIMD) simulations. Plausible structures and their lithiation profiles are cross-validated via Raman/IR spectroscopy and density functional theory (DFT). Lithium bis(fluorosulfonyl)imide (LiFSI) plays versatile roles in the Li-SPAN cell electrochemistry, primarily as the major source in forming the cathode-electrolyte interphase (CEI), further verified via X-ray photoelectron spectroscopy and AIMD. Besides being a charge carrier and CEI composer, LiFSI mediates the PS generation processes in SPAN electrochemical lithiation. Analysis of AIMD trajectories during progressive lithiation reveals that, compared to carbonates, ether solvents enable stronger solvation and chemical stabilization for both salt and SPAN structures. Differentiated CEI formation and electrochemical lithiation decomposition pathways and products are profoundly associated with the intrinsic nature of lithium bonding with oxygen and sulfur.
硫化聚丙烯腈（SPAN）基正极材料的进展有望实现更安全、更高效的锂硫（Li-S）电池性能。为了阐明电解质-正极界面电化学和多硫化物（PS）溶解情况，我们通过分子动力学（AIMD）模拟来模拟放电SPAN反应。通过拉曼/红外光谱和密度泛函理论（DFT）对合理的结构及其锂化曲线进行交叉验证。双（氟磺酰）亚胺锂（LiFSI）在Li-SPAN电池电化学中发挥着多种作用，主要作为形成正极-电解质界面（CEI）的主要来源，并通过X射线光电子能谱和AIMD进一步验证。除了作为电荷载体和CEI组成部分外，LiFSI还介导SPAN电化学锂化过程中的PS生成过程。对逐步锂化过程中AIMD轨迹的分析表明，与碳酸盐相比，醚类溶剂对盐和SPAN结构具有更强的溶剂化作用和化学稳定性。不同的CEI形成以及电化学锂化分解途径和产物与锂与氧和硫键合的内在性质密切相关。
