Bioinspired oxygen selective membrane for Zn-air batteries

摘要

Zn-air and other metal-air batteries suffer from limited shelf life due to carbonization by CO2 and evaporation of water through the cathode. Bioinspired oxygen selective membranes (OSMs) with common similarities to lungs alveoli were prepared and applied as an oxygen selective passive membrane on the cathode of the Zn-air batteries, which limit CO2 and H2O transport while actively supporting O-2 flux. The OSMs were prepared from polycarbonate and iron(II) phthalocyanine in volatile chlorogenic solvent ("breath figures self-assembly" mechanism) under controlled humidity conditions. Membranes were characterized by scanning electron microscopy, UV-visible spectroscopy, and gas chromatography. These membranes contain polycarbonate in a pulmonary alveolus-like structure of 0.2-4.0 microns thick, inclosing iron(II) phthalocyanine as an oxygen carrier molecule. The electrochemical measurements are performed to evaluate the membrane O-2 permeability in both half- and full-cell Zn-air configurations. The effect of relative humidity, iron(II) phthalocyanine, and polycarbonate content is investigated during the optimization of membrane permeabilities and selectivity results. By installing the OSM on top of the cathode of a Zn-air prototype cell, we were able to reduce the water evaporation by 88% while supporting an oxygen limiting current of 73 mA cm(OSM)(-2) with an OSM (PC 11%, FePc 9.1%).