Kang Yuqiong, Deng Changjian, Wang Zhengyang, Chen Yuqing, Liu Xinyi, Liang Zheng, Li Tao, Hu Quan, Zhao Yun
Division of Energy and Environment, Engineering Laboratory for the Next Generation Power and Energy Storage Batteries Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, China.
Hoffmann Institute of Advanced Materials, Shenzhen Polytechnic, Shenzhen, 518055, China.
Nanoscale Res Lett. 2020 May 13;15(1):107. doi: 10.1186/s11671-020-03327-8.
Lithium-ion batteries (LIBs) are currently the most important energy storage system. Separators in the battery play a critical role in terms of the rate capability, cycle life, and safe operation. However, commercial separators exhibit poor electrolyte wettability and limited safety. It is also extremely important to eliminate the hazardous small molecules (e.g., HO and HF) inside the battery to enhance the service life. Herein, a functionalized poly(vinylidene fluoride-co-hexafluoropropylene)@polyacrylonitrile (PVDF-HFP@PAN) separator modified by 4-Å molecular sieves (MS) was fabricated by hydrothermal method for LIBs. MS@PVDF-HFP@PAN separator exhibits high thermal stability and carbonate electrolyte wettability. In addition, it can lower the moisture value in the battery system to 13 ppm, which significantly improves the electrolyte quality. When the current density increased from 0.2 to 5 C, the discharging capacity of the cell with MS@PVDF-HFP@PAN declines from 177.6 to 143.2 mAh g, demonstrating an excellent capacity retention of 80.6%. The discharge capacity retention of NMC622 half-cell with MS@PVDF-HFP@PAN after 100 cycles is 98.6% of its initial discharge capacity, which is higher than that of a cell with the Celgard 2400 separator (91.9%).
锂离子电池（LIBs）是目前最重要的储能系统。电池中的隔膜在倍率性能、循环寿命和安全运行方面起着关键作用。然而，商用隔膜表现出较差的电解质润湿性和有限的安全性。消除电池内部的有害小分子（如HO和HF）以延长使用寿命也极为重要。在此，通过水热法制备了一种由4Å分子筛（MS）改性的功能化聚（偏二氟乙烯-共-六氟丙烯）@聚丙烯腈（PVDF-HFP@PAN）隔膜用于锂离子电池。MS@PVDF-HFP@PAN隔膜具有高热稳定性和碳酸盐电解质润湿性。此外，它能将电池系统中的水分值降低到13 ppm，显著提高了电解质质量。当电流密度从0.2 C增加到5 C时，采用MS@PVDF-HFP@PAN的电池放电容量从177.6 mAh g下降到143.2 mAh g，显示出80.6%的优异容量保持率。采用MS@PVDF-HFP@PAN的NMC622半电池在100次循环后的放电容量保持率为其初始放电容量的98.6%，高于采用Celgard 2400隔膜的电池（91.9%）。
