Department of Materials Science & Engineering, Hanyang University, Seoul 133-791, Korea.
ACS Nano. 2012 Sep 25;6(9):8308-15. doi: 10.1021/nn303002u. Epub 2012 Sep 14.
Titanium dioxide (TiO(2)) is one of the most promising anode materials for lithium ion batteries due to low cost and structural stability during Li insertion/extraction. However, its poor rate capability limits its practical use. Although various approaches have been explored to overcome this problem, previous reports have mainly focused on the enhancement of both the electronic conductivity and the kinetic associated with lithium in the composite film of active material/conducting agent/binder. Here, we systematically explore the effect of the contact resistance between a current collector and a composite film of active material/conducting agent/binder on the rate capability of a TiO(2)-based electrode. The vertically aligned TiO(2) nanotubes arrays, directly grown on the current collector, with sealed cap and unsealed cap, and conventional randomly oriented TiO(2) nanotubes electrodes were prepared for this study. The vertically aligned TiO(2) nanotubes array electrode with unsealed cap showed superior performance with six times higher capacity at 10 C rate compared to conventional randomly oriented TiO(2) nanotubes electrode with 10 wt % conducting agent. On the basis of the detailed experimental results and associated theoretical analysis, we demonstrate that the reduction of the contact resistance between electrode and current collector plays an important role in improving the electronic conductivity of the overall electrode system.
二氧化钛（TiO(2)）是最有前途的锂离子电池阳极材料之一，因为其在锂插入/提取过程中成本低且结构稳定。然而，其较差的倍率性能限制了其实际应用。尽管已经探索了各种方法来克服这个问题，但以前的报告主要集中在提高活性材料/导电剂/粘合剂复合膜中与锂相关的电子电导率和动力学性能上。在这里，我们系统地研究了集流器与活性材料/导电剂/粘合剂复合膜之间的接触电阻对基于 TiO(2)的电极倍率性能的影响。为此研究，我们制备了具有密封帽和无密封帽的垂直排列 TiO(2)纳米管阵列，直接生长在集流器上，以及传统的无规取向 TiO(2)纳米管电极。与具有 10wt%导电剂的传统无规取向 TiO(2)纳米管电极相比，具有无密封帽的垂直排列 TiO(2)纳米管阵列电极在 10 C 倍率下的容量高出六倍。基于详细的实验结果和相关的理论分析，我们证明了电极和集流器之间接触电阻的降低在改善整个电极系统的电子导电性方面起着重要作用。
