Water-Dispersed Poly(p-Phenylene Terephthamide) Boosting Nano-Al<sub>2</sub>O<sub>3</sub>-Coated Polyethylene Separator with Enhanced Thermal Stability and Ion Diffusion for Lithium-Ion Batteries

oleh: Haopeng Cai, Guoping Yang, Zihan Meng, Xue Yin, Haining Zhang, Haolin Tang

Format: Article
Diterbitkan: MDPI AG 2019-08-01

Deskripsi

Polyethylene (PE) membranes coated with nano-Al<sub>2</sub>O<sub>3</sub> 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 &#176;C, the assembled battery from the synthesized composite separator explodes at 3200 s, which is five times longer than the battery assembled from an Al<sub>2</sub>O<sub>3</sub>-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 &#176;C, while the explosion of the battery with Al<sub>2</sub>O<sub>3</sub>-coated PE occurs at 250 s. More importantly, the interface resistance of the cell assembled from the composite separator decreases to 65 &#937;. 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&#8722;discharge cycles. The results described here demonstrate that Al<sub>2</sub>O<sub>3</sub>/PPTA-coated polyethylene membranes have superior thermal stability and ion diffusion.