Screening of Alkaline Zinc Battery Separators using Anodic Stripping Voltammetry

28 Pages·2017·3.07 MB·English

by  Duay, Jonathon

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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