资源化利用废弃印刷线路板可控构筑三维多孔微/纳Cu-Sn复合负极材料及其性能调控

Sn-based materials have exhibited broad application prospects in the field of the lithium ion battery materials because of high theoretical specific capacity and excellent safety. However, huge volume change during lithiation/delithiation process and gradual exhaustion of tin resources have severely restricted their further development. In this project, Cu and Sn enriched solution is firstly obtained from leaching waste printed circuit boards with the self-made environment-friendly and high-efficiency tin-stripping solution, and then the desirably three-dimensional porous micro/nano Cu-Sn composite anode materials are directly prepared on the current collector by in situ pulse electrodeposition and following annealing, which are in accord with the conception concerning production integration from metallurgy to material. Firstly, high-efficiency stripping of soldering tin and zero emissions to the environment will be realized by utilizing the self-made tin-stripping solution. Secondly, the adhesion force between the electrode and the current collector can be strengthened by fabricating the thin-film material via in situ electrodeposition. Thirdly, the electronic conductivity of the surface of the composite material can be enhanced through CNTs composite electrodeposition. Moreover, introducing micro/nano structure and active/inactive system into the Sn-based material will improve the structural stability and the cycle performance of the as-prepared composite materials. The study shows the separation and enrichment mechanism of Cu and Sn from the enriched solution of waste printed circuit boards, the principle of lithium ion intercalation and deintercalation in the composite materials and the law of gradual change and growth of the mesophase alloy compound, the formation and growth law of the SEI film and the response mechanism to volume expansion and pulverization effect of the as-prepared composite electrode materials. These all can provide theoretical guidances and new ideas to develop the electrode materials of lithium ion batteries from comprehensive utilizing waste resources.

锡基材料因理论比容量高和安全性好等优点在锂离子电池材料领域展现出广阔的应用前景，但锂化过程中的巨大体积变化和资源的逐渐枯竭都严重制约了其进一步发展。本项目秉承冶金材料一体化的构想，拟先通过自制的环保高效退锡液处理废弃印刷线路板得Cu、Sn富集液，将其采用原位脉冲电沉积后经退火处理在集流体上直接得到三维多孔微/纳Cu-Sn复合负极材料。利用自制退锡液实现焊锡的高效退除和对环境的零排放；利用原位电沉积制备薄膜材料增强活性材料与集流体间的结合力；利用CNTs复合沉积改善材料表面的电子电导率；利用微/纳结构和活性/非活性体系提高材料结构稳定性和电池循环性能。通过研究，揭示Cu、Sn物料的分离与富集机理，明晰锂离子在复合材料中的脱/嵌机制与中间相合金化合物的渐变生长规律、SEI膜的形成与生长规律及复合材料体积膨胀与粉化效应的应对机制，为综合利用废弃资源开发锂离子电池电极材料提供理论依据和新思路。

锡基材料因理论比容量高和安全性好等优点在锂离子电池材料领域展现出广阔的应用前景，但锂化过程中的巨大体积变化和资源的逐渐枯竭都严重制约了其进一步发展。本项目秉承冶金材料一体化的构想，先通过自制的环保高效退锡液处理废弃印刷线路板得Cu、Sn富集液，将其采用原位脉冲电沉积后经退火处理在集流体上直接得到三维多孔微/纳Cu-Sn复合负极材料。研究表明：自制退锡液实现了焊锡的高效退除和对环境的零排放；原位电沉积制备薄膜材料增强了活性材料与集流体间的结合力；CNTs复合沉积改善了材料表面的电子电导率；微/纳结构和活性/非活性体系提高了材料结构稳定性和电池循环性能。通过工艺优化，获得了电化学性能优异的复合负极材料，室温下，在100 mA g-1电流密度下的首次可逆比容量687.45 mAh g-1，首次库仑效率为85.55 %，循环50次后，容量保持率为82.58 %。此外，还系统地构筑了不同结构的Sn、Si基负极材料，测试结果表明所制备的复合负极材料具有优异的电化学性能。通过本项目的研究，揭示了Cu、Sn物料的分离与富集机理，明晰了锂离子在复合材料中的脱/嵌机制与中间相合金化合物的渐变生长规律、SEI膜的形成与生长规律及复合材料体积膨胀与粉化效应的应对机制，为综合利用废弃资源开发锂离子电池电极材料提供了理论依据和新思路。本项目实施过程中，共发表学术论文32篇，其中SCI检索论文29篇，入选ESI 1‰热点论文2篇，ESI 1%高倍引论文5篇；共申请发明专利5项，其中2项已授权；培养了博士研究生1人，硕士研究生8人。