Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
Department of Material Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
Science. 2018 Mar 30;359(6383):1513-1516. doi: 10.1126/science.aap8787.
Lithium (Li) metal electrodes are not deployable in rechargeable batteries because electrochemical plating and stripping invariably leads to growth of dendrites that reduce coulombic efficiency and eventually short the battery. It is generally accepted that the dendrite problem is exacerbated at high current densities. Here, we report a regime for dendrite evolution in which the reverse is true. In our experiments, we found that when the plating and stripping current density is raised above ~9 milliamperes per square centimeter, there is substantial self-heating of the dendrites, which triggers extensive surface migration of Li. This surface diffusion heals the dendrites and smoothens the Li metal surface. We show that repeated doses of high-current-density healing treatment enables the safe cycling of Li-sulfur batteries with high coulombic efficiency.
锂（Li）金属电极在可充电电池中不可用，因为电化学电镀和剥离总是导致枝晶的生长，从而降低库仑效率，并最终使电池短路。人们普遍认为，在高电流密度下，枝晶问题会加剧。在这里，我们报告了一个枝晶演变的模式，情况正好相反。在我们的实验中，我们发现当电镀和剥离电流密度提高到~9 毫安每平方厘米以上时，枝晶会发生大量的自热，从而引发 Li 的广泛表面迁移。这种表面扩散修复了枝晶，并使 Li 金属表面变得光滑。我们表明，多次高电流密度修复处理可以使 Li-硫电池安全循环，同时保持高库仑效率。
