High nickel LiNi_0.8Co_0.15Al_0.05O₂ (NCA) cathode material has become one of the most promising cathode materials in the field of power batteries, but the side reaction between the conventional LiPF₆-based electrolyte and the surface of the NCA material results in poor material interface stability. In this work, a compatible lithium difluoro(oxalate)borate (LiDFOB)-based electrolyte by the employment of sulfolane (SL) as a representative sulfur-containing solvent has been built to enhance the interfacial stability of NCA electrode. The composition, morphology and electrochemical properties are studied by X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy et al. Results show that the decomposition of LiDFOB on the surface of the positive electrode material contributes to forming a uniform cathode electrolyte interface (CEI) film, which subsequently reduces the dissolution of metal ions and hinders the structure transition of the material from the layered structure to spinel or rock-salt phases. Besides, the sulfur-containing products resulted from the decomposition of SL promote the conductivity of Li⁺ ions for CEI film, which makes up for shortcomings of LiDFOB. Moreover, more LiF has been formed due to the synergistic action between LiDFOB salt and SL solvent, improving the stability and density of CEI film, reducing the thickness of CEI film, and further improving the cycle performance of the battery.

高镍LiNi _0.8 Co _0.15 Al _0.05 O ₂（NCA）正极材料已成为动力电池领域最有希望的正极材料之一，但传统的LiPF ₆之间存在副反应基电解质和NCA材料的表面导致较差的材料界面稳定性。在这项工作中，通过使用环丁砜（SL）作为代表性的含硫溶剂，建立了兼容的二氟（草酸）硼酸锂（LiDFOB）基电解质，以增强NCA电极的界面稳定性。通过X射线光电子能谱，扫描电子显微镜和透射电子显微镜等研究了组成，形态和电化学性质。结果表明，LiDFOB在正极材料表面的分解有助于形成均匀的阴极电解质界面（CEI）膜，随后减少了金属离子的溶解并阻碍了材料从层状结构到尖晶石的结构转变或岩盐相。用于CEI膜的⁺离子，弥补了LiDFOB的缺点。此外，由于LiDFOB盐和SL溶剂之间的协同作用，已经形成了更多的LiF，从而改善了CEI膜的稳定性和密度，减小了CEI膜的厚度，并进一步改善了电池的循环性能。