A leaf-vein-like MnO2@PVDF nanofiber gel polymer electrolyte matrix for Li-ion capacitor with excellent thermal stability and improved cyclability

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2020-05, Vol.387, p.124058, Article 124058
• Main Authors: Shen, Xian-lei, Li, Zong-jie, Deng, Nan-ping, Fan, Jie, Wang, Liang, Xia, Zhao-peng, Kang, Wei-min, Liu, Yong
• Format: Article
• Language: English
• Subjects: Cyclability; Electrolyte; Li-ion capacitor; Nanofiber; Separator; Thermal stability
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.124058

The bionic design of MnO2@PVDF/TBAC LVNM as gel polymer electrolyte matrix for LIC with excellent cycle performance and thermal stability. [Display omitted] •A leaf-vein-like nanofiber gel polymer Electrolyte membrane coated MnO2 nanosheets was fabricated.•The membrane possessed good mechanical property and excellent electrolyte uptake.•The membrane exhibited outstanding cycle stability and excellent thermal stability. Many anode materials are fabricated and their behaviors in Li-ion capacitors (LIC) are investigated to reduce the imbalance of the power capability between the electrodes, which greatly affects the cycle performance of LIC. Yet, the separator of LIC was left out of this contribution. In this work, the in-situ growth of manganese dioxide@polyvinylidene fluoride/tetrabutylammonium chloride (MnO2@PVDF/TBAC) leaf-vein-like nanofiber membrane (LVNM) with enhanced mechanical properties and excellent porosity was developed to effectively improve the ionic conductivity of the matrix and to improve the cycle performance of the LIC. Multi-walled carbon nanotubes (MWCNTs) was employed as reducing agent to produce in-situ growth of MnO2 nanosheets as the shell of the nanofibers, which not only further enhanced the LIC cyclability by providing additional capacity for LIC, but also avoided short circuit problem. The leaf-vein-like structure could greatly enhance the porosity and electrolyte retention of the matrix to accelerate ion transport between the two electrodes. Meanwhile, the in-situ growth of MnO2 nanosheets could promote the thermal stability of the gel polymer electrolyte (GPE) matrix and improve the LIC cycle stability. The MnO2@PVDF/TBAC matrix possessed excellent thermal stability (rose to 170 °C), high porosity (73%) and good ionic conductivity (2.95 * 10−3 S/cm). The LIC assembled with MnO2@PVDF/TBAC LVNM showed enhanced specific capacitance (19.5 F g−1), good rate capability, superior cycling stability (67.20% capacity retention after 10,000 cycles at 0.5 C), and high coulombic efficiency (~100%). Thus, our work provides an effective strategy for enhancing the thermal stability and cyclability of LIC.