Evaluation of a ceramic separator for use in rechargeable alkaline Zn/MnO2 batteries

• Published in: Journal of power sources 2018-08, Vol.395, p.430-438
• Main Authors: Duay, Jonathon, Kelly, Maria, Lambert, Timothy N.
• Format: Article
• Language: English
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2018.05.072

Rechargeable Zn/MnO2 alkaline batteries are a promising technology for grid storage applications since they are safe, low cost, and considered environmentally friendly. Here, a commercial ceramic sodium ion conductor which is impervious to zincate [Zn(OH)42−], a contributor to MnO2 cathode failure, is evaluated as the battery separator. As received, the ionic conductivity of this separator was measured with electrochemical impedance spectroscopy to be 3.5 mS cm−1, while its thickness is 1.0 mm, resulting in large total membrane resistance of 25.3 Ω. Reducing the thickness of the ceramic to 0.5 mm provided for a decreased resistance of 9.8 Ω. Crossover experiments conducted using inductively coupled plasma - mass spectrometry measurements failed to measure any Zn(OH)42− transport indicating a diffusion coefficient that is at least two orders of magnitude less than that for the commercial cellophane and Celgard separators. For 5% DOD at a C/5 rate, the cycle lifetime was increased by over 22% using the 0.5 mm thick ceramic separator compared to traditional Celgard and cellophane separators. Scanning electron microscopy/energy dispersive X-ray spectroscopy and X-ray diffraction characterization of cycled electrodes showed limited amounts of zinc species on the cathode utilizing the ceramic separator, consistent with its prevention of Zn(OH)42− transport. [Display omitted] •NaSICON used here for first time as Zn/MnO2 Battery Separator.•NaSICON reduced the amount of Soluble Zinc Crossover to Cathode.•NaSICON separator was stable over two months in 30% NaOH.•Reducing thickness extended cycle lifetime 122% over Commercial Membranes.