Department of Mechanical Engineering, Sogang University, Seoul 04107, Korea.
Department of Chemical and Biomolecular Engineering, Sogang University, Seoul 04107, Korea.
Sci Rep. 2017 Feb 13;7:42521. doi: 10.1038/srep42521.
Typical cathode materials of Li-ion battery suffer from a severe loss in specific capacity, and this problem is regarded as a major obstacle in the expansion of newer applications. To overcome this, porous cathodes are being extensively utilized. However, although it seems that the porosity in the cathode would be a panacea for high performance of LIBs, there is a blind point in the cathode consisting of porous structures, which makes the porous design to be a redundant. Here, we report the importance of designing the porosity of a cathode in obtaining ultrahigh performance with the porous design or a degraded performance even with increase of porosity. Numerical simulations show that the cathode with 40% porosity has 98% reduction in the loss of specific capacity when compared to the simple spherical cathode when the C-rate increases from 2.5 to 80 C. In addition, the loss over total cycles decreases from 30% to only about 1% for the cathode with 40% porosity under 40 C. Interestingly, however, the specific capacity could be decreased even with the increase in porosity unless the pores were evenly distributed in the cathode. The present analysis provides an important insight into the design of ultrahigh performance cathodes.
锂离子电池的典型阴极材料存在比容量严重损失的问题，这被认为是扩展新型应用的主要障碍。为了克服这个问题，多孔阴极被广泛使用。然而，尽管阴极中的孔隙似乎是提高 LIBs 性能的灵丹妙药，但多孔结构的阴极存在一个盲点，这使得多孔设计变得多余。在这里，我们报告了在获得超高性能的多孔设计或甚至增加孔隙率导致性能下降时，设计阴极孔隙率的重要性。数值模拟表明，与简单的球形阴极相比，当 C 率从 2.5 增加到 80C 时，具有 40%孔隙率的阴极的比容量损失减少了 98%。此外，在 40°C 下，具有 40%孔隙率的阴极的总循环损失从 30%降低到仅约 1%。有趣的是，然而，除非孔隙在阴极中均匀分布，否则比容量即使增加孔隙率也会降低。本分析为超高性能阴极的设计提供了重要的见解。
