连续硅基杂化隔膜涂层对锂离子电池性能的影响

通过卷对卷连续常压等离子体增强化学气相沉积(atmospheric pressure plasma enhanced chemical vapor deposition,AP-PECVD)法,对锂离子电池聚乙烯(PE)隔膜进行涂层,制备了硅基杂化纳米颗粒涂层隔膜。通过衰减全反射傅里叶变换红外光谱仪(ATR-FTIR)、扫描电子显微镜(SEM)和光学接触角测量仪对不同功率密度下涂层隔膜的物化性能进行表征,组装了LiFePO4/Li扣式电池并对其电化学性能进行测试,研究了100次循环后隔膜的表面特性。结果表明:纳米颗粒涂层隔膜含有-COOH、-OH、Si-O-Si、Si-OH等极性亲水基团,可显著降低电解液的接触角,提高润湿性;涂层隔膜的欧姆阻抗(Rs)和电荷迁移阻抗(Rct)显著降低,电导率增加。不同功率密度下的涂层隔膜能显著提高隔膜的物化性能和电池的电化学性能,但涂层隔膜的性能和功率密度之间并不呈正相关的关系,0.83 W/cm2功率密度下的涂层隔膜展示出更优的物化性能和电化学性。1C倍率100次循环后,未处理隔膜和涂层隔膜表面的孔隙都有一定程度的减小且Rs有所增加,但相对未处理的PE,涂层隔膜的颗粒与隔膜表面结合较好,孔径的减小和Rct的增加较少。

Nonlinear Dynamics of Phase Separation in CuCo Alloys

The dynamics of phase separation of CuCo alloys has been studied by numerically solving the nonlinear Cahn-Hilliard equation including thermal noises.The simulations show that phase separation of the alloys within the metastable region is attributed to the composition fluctuations including thermal noises.The present modeling makes it possible to describe the growth and coarsening as concomitant processes.

Dynamics of Spacing Selection for Lamellar Eutectics in Directional Solidification

Profile and its splitting features of solidifying interface of lamellar eutectic in directional solidification have been investigated by solving numerically the nonlinear coupling equation of solidification.It is argued that critical splitting point of the solidifying interface Is marginally stable,and therefore is the possible operating point of spacing selection dynamics.Three modes of the dynamics are proposed,and a new scaling law of the lamellar array is derived,which has a more general form than the classic one.