Screening of Alkaline Zinc Battery Separators using Anodic Stripping Voltammetry PDF
Preview Screening of Alkaline Zinc Battery Separators using Anodic Stripping Voltammetry
Photos placed in horizontal position with even amount of white space between photos and header Screening of Alkaline Battery Separators Using Anodic Stripping Voltammetry October 11, 2017 Jonathon Duay, Timothy N. Lambert, and Ruby Aidun Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525 Rechargeable Alkaline Zn-MnO Batteries 2 Zn-MnO 2 Separators: Cheap Zn MnO KOH 2 • Potash ~ $260 per ton • ~ $1 per lb • ~ $1-2 per lb • Abundant • 25th most abundant • Mn, 12th most abundant • Aqueous • 13,000,000 tons (2012) • 16,000,000 tons (2012) • > Safety than Li-org • Safe • Safe Co $13-15/lb Li $2.5/lb V $11-12/lb Al $0.8-0.9/lb Ni $6-9/lb Cu $2.5-3.5/lb The ultimate challenge in Zn/MnO batteries is reversibility to increase cell lifetime 2 2 Rechargeable Alkaline Zn-MnO Batteries 2 MnO Zn 2 Separators e- H+ Zn(OH) 2- 4 Mn(OH) 3- ZnMn O 2e- 6 2 4 e- KOH KOH Mn(OH) ZnO 2 3 Failure Mechanisms of MnO Cathode 2 Two failure mechanisms for cathode 1. Instability of Mn(III) resulting in formation of irreversible Mn O 3 4 2. Zn poisoning forming irreversible ZnMn O 2 4 4 Need for Selective Separator Research by Ford in the 1980s showed that the MnO cathode 2 could be stabilized at low loadings in the absence of Zinc Full 2e- MnO cathodes Wroblowaet al., J. Electrochem. Soc.(1988)pp. 2415-2418 2 have been shown to be 100% reversible but only in the absence of Zinc thus there is an imperative need for Zinc/Zincate blocking separators 5 Features of a Good Zn Battery Separator OH-, K+, or Na+ High Ionic Conductivity Metric: Electrochemical Impedance Cathode Zinc Electrode Low Zincate Permeability Zn(OH) 2- 4 Metric: Zinc Diffusion Coefficient r o t a r a p e S 6 Features of a Good Zn Battery Separator OH-, K+, or Na+ High Ionic Conductivity Metric: Electrochemical Impedance Cathode Zinc Electrode Low Zincate Permeability Zn(OH) 2- 4 Metric: Zinc Diffusion Coefficient r o t a r a p e S A rapid screening method for the determination of Zn (zincate) membrane/separator permeability is needed 7 Analysis Techniques – ICP/MS Sampling, Dilutions, and Calibration Solutions ©LibreTexts libraries -time intensive Instrumentation -lots of glassware -requires acidic solutions (2% HNO ) 3 -requires total dissolved solids <0.2% -huge dilution >300X Perkin-Elmer -expensive bulky equipment Inductively Coupled Plasma – Mass Spectrometer 8 Analysis Techniques – Complexometric Titration Colormetric Titration w/EDTA Instrumentation Or Perkin-Elmer ©LibreTexts libraries UV/Vis Spectrometer -Difficult Endpoint Determination -Requires pH ≤ 11 -Use of ammonium buffer -Dilution >20X -ppm limits of detection 9 Anodic Stripping Voltammetry (ASV) -historically done on Hg drop electrodes -done in buffered solutions Oxidation/Cleaning of Electrode Oxidation/Stripping of Metal Plating/Accumulation Wikipedia of Metal Analyst, 2012, 137, pp. 614-617 Sensitive -limits of detection (LOD): ppb levels Selective -different metals are resolved by their stripping/oxidation potential
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