ABSTRACT

High-resolution TEM microscopy studies were performed to investigate the crystal structure change of the carbon cathode with sodium intercalation. Although the interlayer spacing changed after electrolysis, the graphite still maintained the clear layer structure. To investigate the electronic structure and mechanical performance of the carbon cathode with intercalation compounds, we performed atomistic simulations. The results indicate that the band gap of the carbon cathode with intercalation compounds becomes narrower, implying a trend of metallization. In addition, the elastic moduli E_a and E_b parallel to basal planes decrease slightly, while E_c normal to carbon surface increases significantly, which results in the rigidity of the carbon cathode with the sodium intercalation to increase and the structure stability to deteriorate. This work can help to better understand the mechanisms of the cathode deterioration and to make further links between the sodium intercalation and the carbon cathode failure.

摘要

进行高分辨率 TEM 显微镜研究以研究碳阴极的晶体结构变化与钠嵌入。尽管电解后层间距发生变化，但石墨仍保持清晰的层状结构。为了研究具有嵌入化合物的碳阴极的电子结构和机械性能，我们进行了原子模拟。结果表明，具有嵌入化合物的碳阴极的带隙变窄，意味着金属化的趋势。此外，平行于基面的弹性模量E _a和E _b略有下降，而 E _c碳表面的法向显着增加，这导致碳阴极的刚性随着钠的嵌入增加而结构稳定性变差。这项工作有助于更好地理解阴极退化的机制，并在钠嵌入和碳阴极失效之间建立进一步的联系。