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

2018 
Abstract Rechargeable Zn/MnO 2 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) 4 2− ], a contributor to MnO 2 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) 4 2− 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) 4 2− transport.
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