Departamento Química Inorgánica. Instituto Universitario de Investigación en Química Fina y Nanoquímica. Universidad de Córdoba . 14071 Córdoba, Spain.
ACS Appl Mater Interfaces. 2014 Mar 12;6(5):3290-8. doi: 10.1021/am405197s. Epub 2014 Feb 20.
Graphene nanosheets (GNS) were used as anodes in full Li-ion cells and LiFePO4 (LFPO) was used as the cathode. A rapid decrease in capacity was observed following the first cycle, the origin of which was assigned to Li consumption in the solid-electrolyte interface (SEI) formation. A reduction of the irreversible capacity from 120 to a value as low as 20 mAh g(-1), similar to a commercial graphite anode, was possible through a prelithiation treatment prior to cell assembling. However, the GNS electrode barely delivered a capacity ca. 40 mAh g(-1) at the end of cycle 50, notably lower than that of the graphite electrode (ca. 100 mAh g(-1)). X-ray photoelectron spectroscopy spectra of the pristine electrodes at the end of 6th and 22nd charges, combined with depth profile analysis, supplied valuable information on the thickness and composition of the SEI. The spectra revealed that the SEI formed on the graphite electrode was much thicker than that formed on the GNS electrode and that its composition was controlled mainly by Li2CO3. The strength and the stability of Li2CO3 are two requisites for establishing a good SEI, which is the reason why the cell made from graphite performed better.
石墨烯纳米片（GNS）被用作全锂离子电池的阳极，而 LiFePO4（LFPO）则被用作阴极。首次循环后，观察到电池容量迅速下降，其原因归因于固体电解质界面（SEI）形成过程中 Li 的消耗。通过在组装电池之前进行预锂化处理，可以将不可逆容量从 120 降低到低至 20 mAh g(-1)的值，与商业石墨阳极相似。然而，在第 50 次循环结束时，GNS 电极几乎没有提供约 40 mAh g(-1)的容量，明显低于石墨电极（约 100 mAh g(-1)）。在第 6 次和第 22 次充电结束时对原始电极进行的 X 射线光电子能谱分析，并结合深度剖析分析，提供了有关 SEI 厚度和组成的有价值的信息。这些谱图表明，在石墨电极上形成的 SEI 比在 GNS 电极上形成的 SEI 厚得多，并且其组成主要由 Li2CO3 控制。Li2CO3 的强度和稳定性是建立良好 SEI 的两个必要条件，这也是为什么由石墨制成的电池性能更好的原因。
