Put Brecht, Vereecken Philippe M, Labyedh Nouha, Sepulveda Alfonso, Huyghebaert Cedric, Radu Iuliana P, Stesmans Andre
KU Leuven , Department of Physics, Celestijnenlaan 200D and ‡KU Leuven Centre for Surface Chemistry and Catalysis, 3001 Leuven, Belgium.
Imec , Kapeldreef 75, 3001 Leuven, Belgium.
ACS Appl Mater Interfaces. 2015 Oct 14;7(40):22413-20. doi: 10.1021/acsami.5b06386. Epub 2015 Oct 5.
Ultrathin LiMn2O4 electrode layers with average crystal size of ∼15 nm were fabricated by means of radio frequency sputtering. Cycling behavior and rate performance was evaluated by galvanostatic charge and discharge measurements. The thinnest films show the highest volumetric capacity and best cycling stability, retaining the initial capacity over 70 (dis)charging cycles when manganese dissolution is prevented. The increased stability for film thicknesses below 50 nm allows cycling in both the 4 and 3 V potential regions, resulting in a high volumetric capacity of 1.2 Ah/cm3. It is shown that the thinnest films can be charged to 75% of their full capacity within 18 s (200 C), the best rate performance reported for LiMn2O4. This is explained by the short diffusion lengths inherent to thin films and the absence of phase transformation.
通过射频溅射制备了平均晶体尺寸约为15 nm的超薄LiMn₂O₄电极层。通过恒电流充放电测量来评估其循环行为和倍率性能。最薄的薄膜显示出最高的体积容量和最佳的循环稳定性，当防止锰溶解时，在70多个充放电循环中保持初始容量。对于厚度低于50 nm的薄膜，稳定性的提高使得其能够在4 V和3 V电位区域内循环，从而产生1.2 Ah/cm³的高体积容量。结果表明，最薄的薄膜能够在18 s内（200 C）充电至其满容量的75%，这是报道的LiMn₂O₄的最佳倍率性能。这可以通过薄膜固有的短扩散长度和不存在相变来解释。
