MOFs改性玻璃纤维膜的制备及其在锂硫电池隔膜中的应用

Preparation of glass fiber membrane modified by metal organic frameworks and its application in diaphragm of lithium-sulfur batteries

利用金属有机框架材料丰富的孔结构来吸附由电池正极产生的溶解性多硫化物,以及科琴黑优良的导电性来减小界面阻抗、活化被吸附的多硫化物,提高电池放电比容量及循环稳定性。采用原位生长法,在玻璃纤维膜表面沉积三种具有不同孔结构的金属有机框架材料UIO-66、MOF-5和ZIF-8;随后在玻纤膜表面涂覆科琴黑,并将其用作锂硫电池隔膜。研究表明:仅用涂覆科琴黑的玻璃纤维膜作为电池隔膜时,锂硫电池在0.2 C倍率下首圈放电比容量为967.4 mAh/g,在循环50圈后容量仅剩730.8 mAh/g;采用不同的金属有机框架材料原位生长的玻璃纤维膜,将其作为锂硫电池隔膜时,锂硫电池表现出不同的循环性能;当使用孔径最大且孔结构最为丰富的UIO-66改性的玻璃纤维膜作为锂硫电池隔膜时,锂硫电池的循环性能最为优异,在0.2 C倍率下首圈放电比容量达1270.1 mAh/g,100圈后仍有827.7 mAh/g。该研究结果为锂硫电池隔膜的制备及改性提供了一种参考方法。

In this paper, the rich porous structure of the metal organic frameworks was used to adsorb dissolved polysulfide produced by the battery cathode and the excellent electric conductivity of Ketjen black was applied to reduce the interface impedance, activate the adsorbed polysulfide, and subsequently improve the discharge capacity and cycling stability of the battery. Three kinds of metal organic frameworks with different porous structure(UIO-66,MOF-5 and ZIF-8) were deposited on the surface of glass fiber by in-situ growth method,respectively. Then, Ketjen black powder was coated on the surface of glass fiber membrane to gain the modified glass fiber membrane which was used as the diaphragm of lithium-sulfur batteries. The experimental results showed that when the glass fiber membrane modified only by Ketjen black was used as the diaphragm, the initial discharge specific capacity of battery was 967.4 mAh/g and 730.8 mAh/g after 50 cycles at 0.2C. When the glass fiber membrane in-situ growing on different metal organic frameworks was used as the battery diaphragm,lithium-sulfur batteries presented different cycling performance.When glass fiber membrane modified by UIO-66 with the largest pore diameter and the richest structure was used as the battery diaphragm, lithium-sulfur batteries presented the best cycling performance.The initial discharge specific capacity reached 1270.1 mAh/g, and 827.7 mAh/g after 100 cycles at 0.2C.This study provides an effective method for preparation and modification of lithium-sulfur battery diaphragm.