Air Dehydration Membranes for Nonaqueous Lithium–Air Batteries

• Published in: Journal of the Electrochemical Society 2010-01, Vol.157 (8), p.A940
• Main Authors: Zhang, Jian, Xu, Wu, Li, Xiaohong, Liu, Wei
• Format: Article
• Language: English
• Subjects: AIR; CAPACITY; CARBON; CATHODES; COATINGS; DEHYDRATION; DIFFUSION; ELECTRODES; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; Lithium-air battery; MEMBRANES; MOISTURE; O2/H2O separation; porous Ni substrate; SUBSTRATES; TEFLON; Teflon membrane; THICKNESS; zeolite membrane; ZEOLITES
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.3430093

In this paper, several types of new membranes were innovated and used as an O2-selective and H2O barrier films attached onto the cathode of non-aqueous Li-air batteries for continuous supplying of dry air into the batteries from ambient air. The membranes were prepared by depositing an O2/H2O selective coating layer on the exterior surface of a newly-invented thin porous Ni substrate sheet at thickness of ~50µm. The coatings tried include hydrophobic silicalite type zeolite and Teflon (PTFE) materials. The melted PTFE-membrane on the porous Ni sheet at 360°C enabled the Li-air batteries with Ketjen black carbon air electrodes to operate in ambient air (with 20% RH) for 21 days with a specific capacity of 1022 mAh/g carbon and a specific energy of 2792 Wh/kg carbon. Its performance is much better than the battery assembled with the same battery material but by use of a commercial, porous PTFE diffusion membranes as the moisture barrier layer on the cathode, which only had a discharge time of five and half days corresponding to a specific capacity of 267 mAh/g carbon and a specific energy of 704Wh/kg carbon. The Li-air battery with the present selective membrane barrier layer even showed better performance in ambient air operation (20% RH) than the reference battery tested in the dry air box (< 1% RH).