Enhancing thermal and ionic conductivities of electrospun PAN and PMMA nanofibers by graphene nanoflake additions for battery-separator applications

Abstract

SUMMARY The present study reports the fabrication and characterization of electrospun polyacrylonitrile (PAN) and polymethyl methacrylate (PMMA) nanofiber separators embedded with graphene nanoflakes. Different weight percentages (0, 2, 4, and 8 wt%) of graphene nanoflakes were dispersed in dimethylformamide (DMF) and ethanol using sonication and high‐speed agitations, and then PAN and PMMA powders were added to the dispersions prior to the mixing process. Ratios of 85:15 for DMF : PAN and 88:12 for ethanol : PMMA were chosen during the dispersion and dissolution processes. After the fabrication of the membranes via the electrospinning process, thermal, dielectric, ionic, and surface hydrophobic properties of the PAN and PMMA nanofiber separators were investigated in detail. Test results revealed that the physical properties, such as wettability, dielectric constant, ionic conductivity, and thermal conductivity values of the nanocomposite separators were significantly increased as a function of graphene concentrations. For example, the water contact angle, ionic conductivity, dielectric constant, and thermal conductivity values of the membranes were increased from 120° to 145°, 3.31 × 10−4 to 5.52 × 10−4 S/m, 3.5 to 8.5 W/m K, and 1.0 to 5.0 W/m K, respectively, when the graphene concentration was increased from 0% to 8% in PMMA. Similar trends were observed in the PAN fibers, as well. Lithium‐ion (Li‐ion) batteries have become the major source of power for portable electronic devices, and because separators are one of the major components of these batteries, the present alternatives can be an option for long‐lasting Li‐ion battery fabrications. Copyright © 2014 John Wiley & Sons, Ltd.

A review of nanofibrous structures in lithium ion batteries

“…In cathodes, common difficulties arise from the relatively high internal resistance, particularly in lithium iron phosphate (LFP) cathodes, as well as degradation during cycling [13e16]. Separator studies mostly focused on improving mechanical strength, durability, and ionic conductivity [17,18]. The present review discusses nanofibrous LIB components separately, in the order of anodes, cathodes, and then separators, based on studies conducted in the last 10 years.…”

Electrospun porous carbon nanofibers as lithium ion battery anodes

“…In recent years, carbon-based materials with various nanostructures, including carbon nanotubes [1,2], graphenes [3][4][5], and carbon nanofibers [6][7][8][9], have been developed to improve the performance of lithium ion batteries. Among these nanomaterials, carbon nanofibers, which possess a straight, continuous, and interconnected structure, can increase the electron-conductive pathway and reduce the distance of lithium ion diffusion, leading to low resistance and high capacity when used as an anode for lithium ion batteries.…”

Modeling and simulation of 2D lithium-ion solid state battery

“…This is mainly a consequence of a lack of established techniques with regards to battery simulation [1]. Many have tried to increase the efficiency of the battery experimentally [29][30][31]. Many have tried to increase the efficiency of the battery experimentally [29][30][31].…”