Water-Dispersed Poly(p-Phenylene Terephthamide) Boosting Nano-Al2O3-Coated Polyethylene Separator with Enhanced Thermal Stability and Ion Diffusion for Lithium-Ion Batteries

Abstract

Polyethylene (PE) membranes coated with nano-Al2O3 have been improved with water-dispersed poly(p-phenylene terephthamide) (PPTA). From the scanning electron microscope (SEM) images, it can be seen that a layer with a honeycombed porous structure is formed on the membrane. The thus-formed composite separator imbibed with the electrolyte solution has an ionic conductivity of 0.474 mS/cm with an electrolyte uptake of 335%. At 175 °C, the assembled battery from the synthesized composite separator explodes at 3200 s, which is five times longer than the battery assembled from an Al2O3-coated polyethylene (PE) membrane. The open circuit voltage of the assembled battery using a composite separator drops to zero at 600 s at an operating temperature of 185 °C, while the explosion of the battery with Al2O3-coated PE occurs at 250 s. More importantly, the interface resistance of the cell assembled from the composite separator decreases to 65 Ω. Hence, as the discharge rate increases from 0.2 to 1.0 C, the discharge capacity of the battery using composite separator retains 93.5%. Under 0.5 C, the discharge capacity retention remains 99.4% of its initial discharge capacity after 50 charge–discharge cycles. The results described here demonstrate that Al2O3/PPTA-coated polyethylene membranes have superior thermal stability and ion diffusion.

Allyl and Benzyl Modified Aramid Nanofibers as an Enhancement in Polystyrene-Based Composites

“…In a recent development of the preparation methods, macroscopic aramid fibers were successfully protonated and dispersed in dimethyl sulfoxide (DMSO) to prepare ANFs (Yang et al, 2011 ). ANFs prepared using this method were subsequently added into matrix materials such as polyurethane (PU) (Kuang et al, 2015 ; Chen et al, 2016 ), poly (vinyl alcohol) (PVA) (Guan et al, 2017 ), polylactic acid (PLA) (Bettini et al, 2017 ), and polyethylene (PE) (Cai et al, 2019 ) for performance enhancement.…”

Al2O3 Thin Layer Formed inside Porous Membrane Using Spray Synthesis Method and Its Application

“…This means that the shrinkage was caused by the residual strain above the temperature at which the film softens. The thermal behavior of pristine PE separators varies greatly depending on the report, with some cases showing significant shrinkage and some cases showing almost no shrinkage [36,37]. This suggests that the thermal shrinkage of the separator is greatly influenced by the manufacturing process.…”

“…The separator in an LIB, which maintains the physical isolation between electrodes, as well as an electrolyte container to provide Li+ ion transport channels during cycling, is a critical part for improving battery performance such as cycle life, energy density, power density, and safety [31][32][33]. Many proposals have been made to improve thermal stability, coating various inorganic particles on the separator surface using a simple bar process or a dip process [34][35][36][37].…”