Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, Xi'an Jiaotong University , Xi'an 710049, China.
Shaanxi Engineering Research Center of Advanced Energy Materials & Devices, Xi'an Jiaotong University , Xi'an 710049, China.
ACS Appl Mater Interfaces. 2016 Mar;8(10):6512-9. doi: 10.1021/acsami.6b00231. Epub 2016 Mar 3.
Coulombic efficiency especially in the first cycle, cycling stability, and high-rate performance are crucial factors for commercial Li-ion batteries (LIBs). To improve them, in this work, Al2O3-coated natural graphite powder was obtained through a low-cost and facile sol-gel method. Based on a comparison of various coated amounts, 0.5 mol % Al(NO3)3 (vs mole of graphite) could bring about a smooth Al2O3 coating layer with proper thickness, which could act as a preformed solid electrolyte interface (SEI) to reduce the regeneration of SEI and lithium-ions consumption during subsequent cycling. Furthermore, we examined the advantages of Al2O3 coating by relating energy levels in LIBs using density functional theory calculations. Owing to its proper bandgap and lithium-ion conduction ability, the coating layer performs the same function as a SEI does, preventing an electron from getting to the outer electrode surface and allowing lithium-ion transport. Therefore, as a preformed SEI, the Al2O3 coating layer reduces extra cathode consumption observed in commercial LIBs.
库仑效率，特别是在第一个循环中，循环稳定性和高倍率性能是商业锂离子电池（LIB）的关键因素。为了改善这些性能，在这项工作中，通过一种低成本且简单的溶胶-凝胶法获得了氧化铝包覆天然石墨粉末。通过比较各种包覆量，0.5mol%Al(NO3)3（相对于石墨的摩尔数）可以带来具有适当厚度的光滑氧化铝包覆层，它可以作为预形成的固体电解质界面（SEI），以减少后续循环中 SEI 的再生和锂离子的消耗。此外，我们通过使用密度泛函理论计算来检查 LIB 中能量水平，从而研究了氧化铝包覆的优势。由于其适当的带隙和锂离子传导能力，涂层层起到了与 SEI 相同的作用，防止电子到达外电极表面并允许锂离子传输。因此，作为预形成的 SEI，氧化铝涂层减少了商业 LIB 中观察到的额外阴极消耗。
