金属锂由于极高理论比容量和低电极电势的特点，成为高比能二次电池的理想负极材料。然而，金属锂的不均匀沉积导致负极循环稳定性差，严重阻碍金属锂负极的实用化。锂沉积均匀性由金属锂负极与电解液之间的、具有一定组成和结构的固态电解质界面膜中锂离子输运均匀性直接决定。调控固态电解质界面膜组成和结构以提升锂离子输运均匀性，是推进金属锂负极实用化的关键。针对目前固态电解质界面膜中锂离子输运特性不明的问题，发展了表征金属锂负极固态电解界面膜中离子输运特性的电化学方法。通过制备富含氟化锂的固态电解质界面膜，演绎验证了氟化锂增强锂离子输运均匀性的作用，深入理解了氟化锂调节锂离子输运的机制，为调控固态电解质界面膜提供了明确的方向。针对固态电解质界面膜缺乏理性调控机制的问题，结合实验表征和理论计算，相继通过添加剂和锂离子溶剂化层设计构筑了锂离子均匀、快速输运的固态电解质界面膜，显著提升了锂沉积均匀性和金属锂负极循环稳定性。基于以上实践，提出了基于锂离子溶剂化层设计以调控固态电解质界面膜组成和结构的机制，为实用化条件下固态电解质界面膜的设计提供了基础。针对少锂、贫电解液等实用化条件对固态电解质界面膜的挑战，指出固态电解质界面膜本质均匀性和循环前后一致性是制约实用化条件下金属锂负极循环寿命的关键因素，提出了可持续固态电解质界面膜的设计策略，即在调控固态电解质界面膜本质均匀性的前提下，通过主溶剂和外源性载体设计持续提供固态电解质界面膜形成所需的前驱体以保证一致性。基于此设计策略构筑的320 Wh kg?1高比能金属锂软包电池可稳定循环100次，展示了该设计策略的实用化潜力。综上所述，本论文在理解固态电解质界面膜中锂离子输运特性和固态电解质界面膜调控实践的基础上，提出了基于锂离子溶剂化层设计以调控固态电解质界面膜的机制，为通过电解液理性调控固态电解质界面膜以提升锂离子输运和锂沉积均匀性提供了新思路，有效指导了实用化条件下高比能金属锂软包电池的构筑。

Lithium metal has been regarded as a promising anode for next-generation high-energy-density batteries due to its extremely high theoretical specific capacity and low electrode potential. However, the non-uniform lithium deposition results in the poor lifespan of lithium metal anode, which severely hinders its practical applications. The uniformity of lithium deposition is dictated by the transport of lithium ion in solid electrolyte interphase with specific components and structure, which exists between lithium metal anode and electrolyte. Therefore, designing solid electrolyte interphase with specific components and structure to improve the uniformity of lithium ion transport is the key foundation to promote the practical applications of lithium metal anode.To unveil the transport mechanism of lithium ion in solid electrolyte interphase on lithium metal anode, electrochemical methods were developed to measure the transport resistance of lithium ion in solid electrolyte interphase. The vital role of lithium fluoride in improving the transport uniformity of lithium ion was syllogistically confirmed by preparing the lithium fluoride-rich solid electrolyte interphase experimentally. The mechanism of lithium fluoride in improving the transport uniformity of lithium ion was uncovered, which provides a clear direction to design solid electrolyte interphase.For rational design principles of solid electrolyte interphase, additives and the design of the solvation sheath of Li ions in electrolyte were employed to construct uniform and stable solid electrolyte interphase by combining experiments and theoretical simulations, significantly improving the uniformity of Li deposition and stability of Li metal anode. Based on the above practice, the regulation of the solvation sheath of lithium ion in electrolytes was proposed as a principle to design solid electrolyte interphase with specific components and structure, guiding the design of solid electrolyte interphase under practical conditions.To construct stable solid electrolyte interphase under practical conditions including limited lithium and lean electrolytes, the inherent uniformity and the consistency of solid electrolyte interphase during cycles was demonstrated as the critical factor in dictating the lifespan of lithium metal anode under practical conditions. A sustainable solid electrolyte interphase was proposed as a design principle in response to the challenges from practical conditions. A sustainable solid electrolyte interphase will be achieved by not only improving the inherent uniformity of lithium ion transport in solid electrolyte interphase, but also providing constant supplements of building blocks of solid electrolyte interphase by the sustained release on an exogenous carrier. A pouch cell of 320 Wh kg?1 at cell level delivered 100 cycles based on a benchmark of 80% capacity retention, exhibiting the huge potential of the design of a sustainable solid electrolyte interphase.In this thesis, the design principle of solid electrolyte interphase by regulating the solvation sheath of lithium ion was proposed based on the fundamental understanding of lithium ion transport in solid electrolyte interphase and the successful construction of uniform and stable solid electrolyte interphase. This thesis provides a fresh ground to rationally design solid electrolyte interphase and improve the uniformity of lithium ion transport, finally promoting the progress of high-energy-density pouch cells with lithium metal anodes.