金属锂负极集流体的微磁场与三维结构协同作用研究

Lithium metal is regarded as the "holy grail" anode material for lithium based batteries, but the problem of lithium dendrite produced during charge and discharge process restricts its further development. This project proposed a novel method of synergetic effects between micro-magnetic field and three-dimensional structure by building a magnetic three-dimensional composite current collector to solving this problem. The stripping/plating behavior of lithium metal will be controlled by magnetohydrodynamic (MHD) effect and magnetizing force produced by the metal permanent magnetic nanoparticles in the current collector, which lead to the formation of fine grains and elimination of lithium dendrites. Furthermore, the three-dimensional structure with large specific surface area will reduce the local current density to inhibit the growth of lithium dendrite, and provide expansion space. The research contents of the project include: the regulation laws of phase and microstructure of the magnetic three-dimensional lithium metal current collector; the diffusion and transmission laws of charge and lithium ion in this new system; the correlation characteristics between phase and structure, electrochemistry and magnetic properties; the relevant calculations about micro-magnetism; the mechanism of micro-magnetic field affecting the lithium metal stripping/plating process; the theoretical model of synergetic effects between micro-magnetic field and three-dimensional current collector. The research idea in the project is novel and feasible, which will enrich the theoretical research of lithium metal anode materials, and it is significant for the development and application of new lithium based battery materials.

金属锂被誉为锂基电池负极材料中的“圣杯”，但充放电过程中产生的锂枝晶制约了其发展。为此，本项目提出构筑磁性三维复合集流体的学术思路，拟利用微磁场和三维集流体的协同作用解决锂枝晶问题，即通过集流体内金属永磁纳米颗粒产生的磁流体力学效应、磁化力作用等调控金属锂的剥离/沉积行为、细化组织、减缓或消除锂枝晶生长；利用三维结构集流体增大比表面积，减小局部电流密度抑制锂枝晶生长并提供膨胀空间等，以获得优异的综合性能。项目研究内容包括：磁性三维金属锂负极集流体的物相与显微结构的调控规律；研究新体系内电荷和锂离子的扩散和传输规律,结合微磁学相关理论计算，阐明物相和结构特征、电化学与磁学性能等三者之间的关联特性，揭示微磁场对金属锂剥离/沉积过程的作用机制，建立微磁场与三维结构集流体的协同作用理论模型。本项目研究思路新颖，将丰富金属锂负极材料的理论研究，同时对新型锂基电池材料的开发与应用具有显著的实际意义。

金属锂一直被誉为是理想的锂电池负极材料，但充放电过程中产生的锂枝晶制约了其发展。为此，本项目通过构筑磁性三维复合集流体的学术思路，利用微磁场和三维结构集流体的协同作用抑制锂枝晶生长，实现锂在集流体内部的深度沉积。即通过集流体内磁性纳米颗粒产生的磁流体力学效应、磁化力作用等调控金属锂的剥离/沉积行为，从而起到细化组织、抑制锂枝晶生长；同时利用三维结构集流体增大比表面积，减小局部电流密度抑制锂枝晶生长并提供膨胀空间等。项目首先采用胶晶模板法合成了一种新型三维有序大孔（3DOM）Cu集流体。3DOM体系结构场可以提供更大的比表面积，抑制锂的体积变化。随后，项目采用脉冲电镀，制备了一种由三维有序大孔/介孔（3DOM/m） Cu/Zn组成的亲锂性多孔集流体。内孔包覆的亲锂性金属Zn可促进锂的孔内形核，提高空间的利用率。此外，还通过去合金化的方法，利用黄铜制备亲锂的3D CuZn集流体。残留在骨架内部的CuZn相可诱导锂的内部形核，抑制锂枝晶的生长，显著改善电池性能。同时在此基础上引入微磁场，即在三维集流体上负载磁性粒子，同时利用磁场在电池内部引入微磁场。磁场MHD效应减小电极表面锂离子的浓差极化，三维结构/微磁场协同促进了锂的均匀形核和生长，从而抑制了锂枝晶生长。为了改善铜集流体的疏锂性，同时充分利用泡沫铜内部大空间，项目通过将镍钴合金和氧化锌负载到泡沫铜上，引入的微磁场有效促使锂在三维集流体内部的深度沉积。本项目研究思路新颖，丰富了金属锂负极材料的理论研究，并对新型锂基电池材料的开发与应用具有显著的实际意义。