Key Laboratory of Advanced Micro/Nanomaterials and Batteries/Cells (Ministry of Education) and Institute of New Energy Material Chemistry, Chemistry College, Nankai University, Tianjin 300071, People's Republic of China.
J Chem Phys. 2010 Jul 21;133(3):034701. doi: 10.1063/1.3462998.
The major hurdle that retards the practical application of nanostructured silicon anode in rechargeable Li-ion batteries is the capacity retention during lithiation/delithiation processes, especially at high current rate (e.g., >5 C). Since fast Li transport in the electrode is the essential of high-rate capability, the rate-limiting step exists during Li transport process and needs to be determined. We here investigate Li transport properties of Si thin film anode by first-principles calculation and find that high intrinsic energy barrier (0.88 eV) of Li surface intercalation retards fast Li transport. However, this energy barrier can be efficiently reduced by surface modification, e.g., P or Al doping. The present results should shed light on designing Si anode of Li-ion batteries with high-rate capability.
在可充电锂离子电池中，纳米结构化硅阳极的实际应用受到阻碍，主要是因为在锂化/脱锂过程中容量保持率低，尤其是在高电流速率（例如，>5C）下。由于电极中快速的 Li 传输是高倍率性能的关键，因此在 Li 传输过程中存在限速步骤，需要确定该步骤。我们通过第一性原理计算研究了 Si 薄膜阳极的 Li 输运性质，发现 Li 表面嵌入的固有高能量势垒（0.88eV）阻碍了 Li 的快速传输。然而，通过表面修饰（例如 P 或 Al 掺杂）可以有效地降低这个能量势垒。本研究结果为设计具有高倍率性能的锂离子电池 Si 阳极提供了思路。
