Liu Changyong, Cheng Xingxing, Li Bohan, Chen Zhangwei, Mi Shengli, Lao Changshi
Additive Manufacturing Research Institute, College of Mechatronics and Control Engineering, Shenzhen University, Shenzhen 518060, China.
Division of Advanced Manufacturing, Graduate School at Shenzhen, Tsinghua University, Beijing 518000, China.
Materials (Basel). 2017 Aug 10;10(8):934. doi: 10.3390/ma10080934.
LiFePO₄ (LFP) is a promising cathode material for lithium-ion batteries. In this study, low temperature direct writing (LTDW)-based 3D printing was used to fabricate three-dimensional (3D) LFP electrodes for the first time. LFP inks were deposited into a low temperature chamber and solidified to maintain the shape and mechanical integrity of the printed features. The printed LFP electrodes were then freeze-dried to remove the solvents so that highly-porous architectures in the electrodes were obtained. LFP inks capable of freezing at low temperature was developed by adding 1,4 dioxane as a freezing agent. The rheological behavior of the prepared LFP inks was measured and appropriate compositions and ratios were selected. A LTDW machine was developed to print the electrodes. The printing parameters were optimized and the printing accuracy was characterized. Results showed that LTDW can effectively maintain the shape and mechanical integrity during the printing process. The microstructure, pore size and distribution of the printed LFP electrodes was characterized. In comparison with conventional room temperature direct ink writing process, improved pore volume and porosity can be obtained using the LTDW process. The electrochemical performance of LTDW-fabricated LFP electrodes and conventional roller-coated electrodes were conducted and compared. Results showed that the porous structure that existed in the printed electrodes can greatly improve the rate performance of LFP electrodes.
磷酸铁锂（LiFePO₄，LFP）是一种很有前景的锂离子电池正极材料。在本研究中，首次采用基于低温直写（LTDW）的3D打印技术制备三维（3D）LFP电极。将LFP油墨沉积到低温腔室中并固化，以保持打印特征的形状和机械完整性。然后将打印好的LFP电极冷冻干燥以去除溶剂，从而获得电极中的高度多孔结构。通过添加1,4 - 二氧六环作为冷冻剂，开发出了能够在低温下冻结的LFP油墨。测量了所制备LFP油墨的流变行为，并选择了合适的成分和比例。开发了一台LTDW机器来打印电极。对打印参数进行了优化，并对打印精度进行了表征。结果表明，LTDW能够在打印过程中有效地保持形状和机械完整性。对打印的LFP电极的微观结构、孔径和分布进行了表征。与传统的室温直接墨水书写工艺相比，使用LTDW工艺可以获得更高的孔体积和孔隙率。对LTDW制备的LFP电极和传统辊涂电极的电化学性能进行了测试和比较。结果表明，打印电极中存在的多孔结构可以大大提高LFP电极的倍率性能。
