Construction of porous coating layer and electrochemical performances of the corresponding modified polyethylene separators for lithium ion batteries

Abstract

To effectively improve the affinity of polyethylene (PE) separators with liquid electrolyte without causing a serious pore blockage and to develop a more suitable technology for the industrial production process, porous polyvinylidene fluoride (PVDF) layer‐coated PE separators are prepared by the dip‐coating method followed by a dry‐cast process. Different from previous investigations, a less volatile solvent and a relatively volatile nonsolvent are used to yield a preferable pore structure. A brief introduction on the pore formation mechanism during the dry‐cast process is provided. The pore structure of coating layer is found to be successfully controlled by changing evaporation temperature, nonsolvent content, and PVDF concentration. The porous PVDF coating layer‐modified separators show better affinity with liquid electrolyte and thermal stability. Especially, the ionic conductivity of the modified separator/liquid electrolyte system with a suitable porous coating layer on the separator could reach two times as that of PE separator/liquid electrolyte system, and the cell assembled with modified PE separator shows better cycle performances. This modification process is proved to be a facile, controllable, and effective method for PE separator modification. Meanwhile, this work could provide some theoretical and technical guidance for the production process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41036.

Fabrication of a nano-Li+-channel interlayer for high performance Li–S battery application

“…However, given that the nano-Li + -channel PVDF interlayer was much denser in structure, the electrolyte uptake of 28.1% is a quite excellent value. As reported elsewhere, 59 the micro porous PVDF interlayer could absorb more than 200% electrolyte, caused by the excellent electrolyte wettability of PVDF polymers. As a result of the "solvation effect" between DME/DOL and -CH 2 -CF 2 -polymer chains, the 3D size of the nano-Li + -channel PVDF interlayer expanded in accordance.…”

Composite Nanofibers as Advanced Materials for Li-ion, Li-O2 and Li-S Batteries

“…PP/PE/PP) polymer separator [65]. These coated polymers improve the Celgard mono layer PP separator qualities by acting as pores multipliers, improving the close niche nanofiberous structure and thus significantly reducing the thermal shrinkage of the separator, and improving the electrolyte uptake and its adhesion to the electrode[47, 300,301]. To improve both the thermal, ionic conductivity, and interfacial properties with lithium electrodes of these nonwoven fibrous separator mat, inert ceramic oxides fillers such as silicon dioxide (SiO2), titanium dioxide (TiO2) and alumina (Al2O3) are generally incorporated into the base polymer matrix [54, 298,[302][303][304][305][306].…”

Thin buffer layer assist carbon-modifying separator for long-life lithium metal anodes

“…The C-TBL and CFL separator exhibits a slightly raised ionic conductivity compared to the pristine PP/PE separator. This is likely ascribed to the improved electrolyte wettability resulting from the enhancement of porosity by porous carbon as reported previously [43,44]. The influences of the BL thickness on the ion conduction properties of the BL separators are further investigated as shown in Fig.…”