基于低温直写的3D打印三维锂离子电池制造及电池性能研究

The application of three-dimensional printing (3DP) in functional devices has been the future trends of this technology. Three-dimensional (3D) lithium-ion battery can avoid the contradiction between energy density and power density that exists in conventional two-dimensional (2D) lithium-ion battery. There are some limitations in current 3D-printed lithium-ion battery at room temperature including insufficient printability and limited study on the influence of slurry components/proportions and macro/micro structures on the electrochemical performance. Therefore, the 3DP technology based on low temperature direct writing is applied to fabricate 3D lithium-ion battery for the first time. By using this technology, the printability can be greatly improved since the slurry is deposited at low temperature. In addition, the thermally induced phase separation during the printing process can be used to regulate the microstructures of the printed electrodes. The size and shape of the printed battery can be precisely controlled and the electrochemical performance can be improved through the optimization of battery macro and micro structures. Toward this goal, the slurry that is appropriate for low temperature deposition will be prepared and the influence of slurry components/proportions on the electrochemical performance will be studied. 3D lithium-ion batteries with different shapes, sizes and microstructures will be printed and the impact of macro/micro structures on electrochemical performance will be investigated. Previous research has demonstrated the advantages and potential of low temperature direct writing. This research project will provide a new manufacturing technology to fabricate 3D lithium-ion batteries and scientific basis for the design of 3D lithium-ion batteries.

3D打印功能器件是3D打印的发展趋势，三维锂离子电池可从结构上避免二维锂离子电池能量密度与功率密度的矛盾，具有重要研究价值。目前室温3D打印三维锂离子电池的成型性能较差、浆料组分配比及电极宏微观结构对电池性能的影响规律尚不明确。本项目首次使用低温直写3D打印制备三维锂离子电池，通过低温固化提高电池浆料的成型性能，使用成型过程中的热致相分离调控微观孔隙结构，精确控制电池的形状和尺寸，从结构角度调控和提升电池性能。围绕低温直写3D打印三维锂离子电池，设计制备适合于低温固化成型的电极浆料，研究揭示浆料组分配比对打印流变性能和电化学性能的影响规律；制备不同宏观结构/特征尺寸的三维锂离子电池，通过低温成型工艺调控电极微观孔隙结构，研究揭示宏微观结构对电化学性能的影响和调控机制。本项目前期研究验证了低温直写3D打印的技术优势和可行性，将开拓一种新型的三维锂离子电池制造技术，为其结构设计提供科学依据

锂离子电池是最为重要的储能器件之一，但目前的锂离子电池技术仍然面临着诸多挑战。传统的涂布电极叠层或卷绕式结构存在能量密度与功率密度的矛盾，为解决上述矛盾，基于3D打印的三维锂离子电池制造技术提供了一种新的途径。本项目提出基于低温直写3D打印的三维锂离子电池制造技术，将锂离子电池正负极浆料沉积到低温环境中固化成形，实现三维电极的制造，后续通过冷冻干燥制造出具有高孔隙率、高比表面积的三维锂离子电池。通过本研究，研制出了适合于低温3D打印的专用锂离子电池正极LiFePO4和负极Li4Ti5O12浆料，表征了其流变性能，并优化了其制造工艺，制造出了孔隙率达到65%~70%的三维电极。表征了电极的微观结构、力学性能、孔隙特征与电化学性能。研究了浆料的组分配方、固含量等对电极微观结构和电化学性能的影响，并对比了传统涂布工艺、常规的室温3D打印工艺以及低温直写3D打印工艺所制造电极的性能。通过研究发现，固含量过低或者过高对电极的微观结构、孔隙率和电化学性能均有比较明显的影响。当固含量过低时，3D打印电极性能不及涂布电极；而当固含量过高时，3D打印电极的性能也有有所下降；而当固含量合适时，3D打印电极表现出最优的性能。另外，我们还制造出了具有超高面负载量的Li4Ti5O12负极，面负载量达到32.3 mg cm-2，面容量密度达到4.8 mAh cm-2，表现出优异的性能。我们还基于COMSOL建立了三维锂离子电池的电化学仿真模型，研究了结构对性能的调控规律，为三维锂离子电池的性能优化奠定了基础。本项目的研究建立了基于低温直写3D打印的锂离子电池专用浆料、专用工艺以及性能表征的全流程技术及方案，为三维锂离子电池走向应用奠定了基础。