INVESTIGATION OF CAPACITY FADE IN FLAT-PLATE RECHARGEABLE ALKALINE MnO2/Zn ...

146 Pages·2016·7.6 MB·English

INVESTIGATION OF CAPACITY FADE IN FLAT-PLATE
RECHARGEABLE ALKALINE MnO /Zn CELLS
2

by

Sean Mehta

A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF
THE REQUIREMENTS FOR THE DEGREE OF

MASTER OF SCIENCE

in

The Faculty of Graduate and Postdoctoral Studies

(Chemical and Biological Engineering)

THE UNIVERSITY OF BRITISH COLUMBIA
(Vancouver)

January 2016

©Sean Mehta, 2016
Abstract

The rechargeable alkaline manganese dioxide-zinc (RAMTM) battery system has been difficult to
commercially develop in the past due to irreversible phase formation and progressive and cumulative
capacity fade. This system has many advantages however, such as low cost and environmentally
sustainable materials, long shelf life, moderate energy density, and safety. A flat-plate architecture was
developed and investigated in half and full-cell apparatuses with the goal of understanding and improving
cumulative capacity fade in the electrolytic manganese dioxide (EMD) cathode.
Two types of cathode current collectors (CCs) were developed, a thin film foil CC and an expanded metal
mesh CC and used to assess the effect of various additives over 30+ cycles under various operating
conditions. Conductive carbon black (Super C65) and graphite (KS44) additives were shown to improve
cell performance at 15 wt. % KS44 graphite providing an electrically conductive network between adjacent
EMD particles.
In addition, other chemical additives (BaSO , Sr(OH) ·8H O, Ca(OH) , and Bi O ) were investigated at 5 wt.
4 2 2 2 2 3
% with Bi O providing a reproducible improvement over a control recipe. Mechanical stability of the
2 3
cathode electrode and pressure application were significant causes of cell failure. Slow rates of discharge,
and shallow depth of discharge (DOD) charge/discharge protocols reduced capacity fade by limiting
electrochemically irreversible phase formation such as Mn O , Mn O , Zn MnO , and Mn(OH) . Analytical
2 3 3 4 2 4 2
characterization techniques including Scanning Electron Microscopy/ Energy Dispersive X-Ray
Spectroscopy (SEM/EDS), X-Ray Photoelectron Spectroscopy (XPS), Powder X-Ray Diffraction (XRD), and
Potentiostatic Electrochemical Impedance Spectroscopy (PEIS) were used to provide supporting evidence
indicating that the main causes of capacity fade are linked to the cathode electrode’s mechanical
properties, increased cell resistance, and progressive and irreversible phase formation.
ii
Preface

The work presented in this thesis was conducted in the David P. Wilkinson laboratory at UBC chemical and
biological engineering (CHBE) and Clean Energy Research Centre (CERC). Under the supervision of and
regular discussion with Dr. David P. Wilkinson and Dr. Arman Bonakdarpour, I performed all laboratory
work (besides that which is stated here), data analysis, and writing.
A Co-op student, Faye Cuadra helped to prepare cells which are presented in section 3.1.3 with time cut-
off and shallow depth of discharge protocols. Several Co-op students (Kimia Yeganeh, Faye Cuadra,
Beichen Zhang, and William Xi) helped to prepare electrolyte and electrode samples (control and 5 wt. %
BaSO in Figure 3.30) which are in part presented in section 3.3.2. Greg Afonso was responsible for the
4
design and manufacturing of the full and half-cell hardware (and multiple iterations thereof) presented in
Figures 2.1 - 2.3.
A subset of this work investigating cathode additives and rate capability studies has been submitted for
publication, titled “Impact of Cathode Additives on the Cycling Performance of Rechargeable Alkaline
Manganese Dioxide-Zinc Batteries”. Mehta, S.;Bonakdarpour, A.; Wilkinson, D. P. A second manuscript
is in progress at the submission date of this thesis, discussing the development of flat-plate rechargeable
alkaline manganese dioxide-zinc cells with and without BaSO as a chemical additive in the cathode.
4

iii
Table of Contents

Abstract ........................................................................................................................................................ ii
Preface ......................................................................................................................................................... iii
Table of Contents ........................................................................................................................................ iv
List of Tables ................................................................................................................................................ vi
List of Figures ............................................................................................................................................. viii
Acknowledgements ....................................................................................................................................xiii
1 Introduction ............................................................................................................................................... 1
1.1 Electrochemical Battery Energy Storage Technologies ............................................................. 1
1.1.1 Electrochemical Battery Energy Storage – Basics, Demand and Growth ................................ 1
1.1.2 Alkaline Cell Raw Materials Economics .................................................................................... 3
1.1.3 Rechargeable Alkaline Electrochemical Energy Storage Technologies .................................... 6
1.1.4 Basic Operation of the MnO /Zn Alkaline Cell ......................................................................... 9
2
1.2 The Alkaline Cell ...................................................................................................................... 11
1.2.1 History of the Alkaline Cell ..................................................................................................... 11
1.2.2 Alkaline Cell Electrochemistry ................................................................................................ 13
1.2.3 Cathode Capacity Failure ....................................................................................................... 15
1.3 Manganese Dioxide Properties ............................................................................................... 17
1.3.1 Manganese Dioxide Solid State Chemistry ............................................................................ 17
1.3.2 Synthesis of Manganese Dioxide ........................................................................................... 18
1.4 Recent Advancements in Rechargeable Alkaline Cells ........................................................... 19
1.4.1 Cathode Additives .................................................................................................................. 19
1.4.2 Flat-Plate Architecture ........................................................................................................... 21
1.5 Objectives ................................................................................................................................. 23
2 Experimental Methods ............................................................................................................................ 24
2.1 Electrochemical Measurements .............................................................................................. 24
2.1.1 Electrochemical Measurements: Experimental Full-Cell Setup ............................................. 24
2.1.2 Electrochemical Measurements: Half-Cell Setup .................................................................. 26
2.1.3 Electrochemical Measurements: Cell Cycling Regimes .......................................................... 29
2.2 Electrode Current Collectors ................................................................................................... 31
iv
2.3 Analytical Characterization ..................................................................................................... 34
2.3.1 X-Ray Diffraction (XRD) Studies ............................................................................................. 34
2.3.2 Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS) ...... 35
2.3.3 Potentiostatic Electrochemical Impedance Spectroscopy (PEIS)........................................... 37
2.3.4 X-Ray Photoelectron Spectroscopy (XPS) ............................................................................. 38
2.3.5 Galvanostatic Intermittent Titration Technique (GITT) ........................................................ 39
3 Results and Discussion ........................................................................................................................... 40
3.1 Effect of Different Operating Conditions ................................................................................ 40
3.1.1 In-Situ Pressure Application ................................................................................................... 40
3.1.2 Depth of Discharge (DOD) ...................................................................................................... 43
3.1.3 Charging and Discharging Protocols ...................................................................................... 46
3.1.4 Galvanostatic Intermittent Titration Technique (GITT) ......................................................... 53
3.1.5 Differential Capacity Analysis ................................................................................................. 55
3.1.6 Coulombic and Energy Efficiency ........................................................................................... 57
3.1.7 Cyclic Voltammetry ................................................................................................................ 59
3.2 Electrode Thickness Effects ...................................................................................................... 61
3.2.1 Scalability and Mass Production Potential ............................................................................. 61
3.2.2 Effect of Current Collector on Identical Cathode Mix ........................................................... 64
3.2.3 Current Collector Discharge Profile Comparison ................................................................... 66
3.3 Effect of Cathode Additives ..................................................................................................... 69
3.3.1 Conductive Additives (KS44 graphite, Super C65 Carbon Black) ........................................... 69
3.3.2 Effect of Cathode Additives on Cycling Performance ............................................................ 75
3.3.3 Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS) ...... 84
3.3.4 Powder X-Ray Diffraction (XRD) Analysis of the Cathode Electrode ..................................... 90
3.4 Analytical Characterization ...................................................................................................... 99
3.4.1 X-Ray Photoelectron Spectroscopy (XPS) Measurements ..................................................... 99
3.4.2 Potentiostatic Electrochemical Impedance Spectroscopy (PEIS)......................................... 100
4 Future Work and Recommendations.................................................................................................... 104
4.1 Improvements in Cell Fabrication and Assembly .................................................................. 104
4.1.1 Effect of Binder .................................................................................................................... 104
4.1.2 Effect of Gelling Agent ......................................................................................................... 105
4.1.3 Effect of Sonication vs. Ball Milling ...................................................................................... 105
v
4.1.4 Current Collector Active Material Loading Density ............................................................. 106
4.1.5 Effect of Mixing/Electrode Homogeneity ............................................................................ 107
4.1.6 Automated Electrode Processing ......................................................................................... 107
4.1.7 Electrolyte Preparation, Dispensation, and Composition .................................................... 108
4.1.8 Anode Performance ............................................................................................................. 110
4.2 Improvement in Cell Performance through Materials Synthesis, Cathode Additives, and
Characterization ........................................................................................................................... 111
4.2.1 Conductive Additives ........................................................................................................... 111
4.2.2 Cathode Additive Studies ..................................................................................................... 112
4.2.3 Alternative Synthesis Conditions of EMD ............................................................................ 114
4.2.4 Cell Setup to Focus on EMD Materials Testing .................................................................... 115
4.2.5 Analytical Characterization .................................................................................................. 115
4.3 Industry Recommendations ................................................................................................... 116
5 Conclusions ............................................................................................................................................ 119
Bibliography.............................................................................................................................................. 123
Appendices ............................................................................................................................................... 128
Appendix A – Materials Preparation ............................................................................................. 128
Appendix B – Materials Information ............................................................................................. 130
Appendix C - Instrumentation ....................................................................................................... 132

vi
List of Tables

Table 1.1: Common (Non-Exhaustive) Electrochemical Storage Technologies ........................................ 1
Table 1.2: Electrochemical Energy Storage Key Feature Comparison ..................................................... 8
Table 1.3: Alkaline Cell History ................................................................................................................. 11
Table 1.4: Rechargeable Alkaline Cell Cathode Additives ......................................................................... 21
Table 1.5: Advantages of Rechargeable Alkaline MnO /Zn Battery Chemistry (left) and Flat-Plate Cell
2
Architectures (right) .................................................................................................................................. 22
Table 2.1: 10 A/m2 H Evolution Reaction (HER) Overpotentials for Common Metals ............................ 27
2
Table 2.2: Comparison of Cathode Electrode Current Collectors ............................................................. 33
Table 3.1: Comparison of estimated voltage losses dependent on rate of discharge ............................. 47

Table 3.2: Comparison of key parameters for thin film foil and expanded metal mesh CCs ................... 62

Table 3.3: Important parameters of Super C65 carbon black and KS44 graphite .................................... 69

Table 3.4: Published cathode compositions and rationale for testing ..................................................... 76
Table 3.5: Cathode additive chemical formula, molar mass, and solubility in water at 20oC .................. 77

Table 4.1: EMD to cathode additive molar ratio at 5 wt. % ...................................................................... 114

vii
List of Figures

Figure 1.1 - Battery Types Market Distribution (2009)1 ............................................................................ 2
Figure 1.2 - Manganese Ore Production by Country (2007-2011 average)2 ............................................ 3
Figure 1.3 - Relative cost per Watt-hour of common electrochemical battery energy storage
technologies (2009)3 ................................................................................................................................. 5
Figure 1.4 - Volumetric and Gravimetric Energy Density of Common Electrochemical Battery
Storage Technologies4 ............................................................................................................................... 7
Figure 1.5 - Alkaline Electrochemical Cell: a) MnO cathode, b) Zinc anode, c) Separator, d) Potassium
2
Hydroxide (KOH) electrolyte, e) External Load. ........................................................................................ 10
Figure 1.6 - Typical Voltage Capacity Plot of MnO /ZnCell in Flat-Plate Configuration with C/10 Rate
2
of discharge to 0.9 V. Capacity vs. cycle data for this cell is presented in Figure 1.2.3 ........................... 15
Figure 1.7 - Capacity vs. cycle for AA cylindrical alkaline cell (continuous 10 Ω discharge to 0.9 V at
room temperature5) vs. flat-plate cell (C/10 rate of discharge to 0.9 V at room temperature). ............. 16
Figure 1.8 - Electrolytic Manganese Dioxide Structure6 ........................................................................... 17
Figure 1.9 - Proposed Electrolytic Manganese Dioxide Structure including Ruetschi Defects7................ 18
Figure 1.10 - Flat-Plate (left)8 and Cylindrical Bobbin (right)9 Rechargeable Alkaline MnO /Zn Cell
2
Architectures ............................................................................................................................................. 22
Figure 2.1 - Flat-Plate Rechargeable Alkaline Full-Cell Setup ................................................................... 24
Figure 2.2 - Schematic of Half-Cell Setup of EMD-based Cathode ........................................................... 28
Figure 2.3 - 3D rendering of half-cell hardware. Designed and manufactured by Greg Afonso .............. 29
Figure 2.4 - 3 step charge/discharge protocol. 1) Galvanostatic discharge, 2) Galvanostatic Charge, 3)
Potentiostatic Charge. .............................................................................................................................. 30
Figure 2.5 - Cathode Electrode Current Collectors (CCs): Nickel Foil (top) and Expanded Nickel Mesh
(bottom) .................................................................................................................................................... 32
Figure 2.6 - Electrode fabrication procedures for expanded nickel mesh (left) and thin film nickel foil
(right) CC showing flexibility of both types of electrodes ......................................................................... 34
Figure 2.7 - Scanning Electron Microscopy Interaction Volume10 ............................................................ 36
Figure 2.8 - Idealized Nyquist plot noting bulk resistance (R) and charge transfer resistance (R ) with
s ct
equivalent circuit model ........................................................................................................................... 37

viii
Figure 3.1 – Current and Voltage vs. Time profile for no stack pressure applied (a) and 47 psi (3.3
kg/cm2) applied pressure (b). Cell discharged at a C/10 rate to -0.4 V vs.Hg/HgO in the flood half-cell
setup....................................................................................................................................................... 40

Figure 3.2 - Voltage capacity profiles for 47 psi (30kg/cm2) stack pressure (a) and no applied pressure
(b) for cycles 1, 3, and 5. Arrows indicate the directions of charge and discharge................................. 41

Figure 3.3 - Capacity vs. cycle number for 47 psi (3.3 kg/cm2) electrode stack pressure and no stack
pressure .................................................................................................................................................... 42

Figure 3.4 - Uniform (left) and non-uniform (right) pressure distribution observed by the use of
pressure sensitive paper ........................................................................................................................... 43

Figure 3.5 - Delamination of an electrode after cycling in a flooded half-cell setup. Electrode cut in
half with scissors after being removed from flooded half-cell setup ....................................................... 43

Figure 3.6 - Voltage vs. Capacity for 1.1, 0.9, 0.5 V potential cut-off for first and fifth cycles ................. 44

Figure 3.7 - Differential capacity profile for 0.5 V (a), 0.9 V (b), and 1.1 V (c) cut-off potentials for the
first and fifth cycles. Charge/discharge voltage vs. capacity profiles for 0.5 V, 0.9 V, and 1.1 V cut-off
potentials for the first (d) and fifth (e) cycle ............................................................................................. 45

Figure 3.8 - Voltage capacity profile of baseline cells at C/1, C/10, and C/20 rates for first cycle with a
1.1 V cut-off. ............................................................................................................................................. 47

Figure 3.9 - Capacity and end of discharge potential for C/10 rate time cut-off of full MnO /Zncells at
2
10 and 25% time cut-off depth of discharge ............................................................................................ 48

Figure 3.10 - Shallow discharge (1.35 V C/2 rate and 1.4 V C/10 rate) with intermittent deep discharge
(1.1 V) capacity vs. cycle ........................................................................................................................... 50

Figure 3.11 - Power and voltage versus capacity with 20 mA galvanostatic discharge at C/10 rate of
discharge ................................................................................................................................................... 51

Figure 3.12 - C/40 Rate discharge, 12 hour discharge (30% depth of discharge): a) voltage capacity
profile, b) cut-off potential and specific capacity vs. cycle, and c) projected cell lifetime in pressurized
half-cell setup ............................................................................................................................................ 52

Figure 3.13 - Voltage vs. fraction of total discharge for C/1, C/5, C/10, C/20, and C/40 rates of discharge
to 1.1 V cut-off potential. GITT measurements at C/2 rate of discharge with 20 minutes discharge, 30
minutes rest period ................................................................................................................................... 54

Figure 3.14 - Voltage capacity profiles of cells at C/1, C/10, and C/20 rates showing polarization
potential losses (a) and polarization potential losses vs. relative current for C/1, C/2, C/5, C/10, C/20,
and C/40 rates of discharge (b) ................................................................................................................. 55
ix
Figure 3.15 - Differential capacity plot for control recipe cycles #1, #10, and #20 showing capacity
fade. Figure is annotated to show discharge peak 1 (DP1), discharge peak 2 (DP2), and charge peak
1 (CP1) ....................................................................................................................................................... 56

Figure 3.16 - Differential capacity plots for control (a) and all additives at 5 wt. % (BaSO (b), Ca(OH)
4 2
(c), Sr(OH) ·8H O (d), Bi O (e)) cycles 1, 3, and 5 with absolute value of differential capacity
2 2 2 3
discharge/charge peak height vs. cycle number (inset) and cycle 1 differential capacity for control and
all additives (f) ........................................................................................................................................... 57
Figure 3.17 - Coulombic (C.E.) and energy efficiency (E.E.) vs. cycle number for all additives at 5 wt. %
with thin film foil CC electrodes ................................................................................................................ 59

Figure 3.18 - 0.05 mv/s CV of EMD-based cathode in half-cell setup (blue) with voltage vs. time (inset)
and differential capacity (red) showing unique redox processes. ............................................................ 60
Figure 3.19 - Top view (left) showing electrode surface and side view (right) showing electrode width
after processing ........................................................................................................................................ 61

Figure 3.20 - Optical micrographs of nickel foam (left), nickel foil (centre), and expanded nickel mesh
(right) at 4x (top) and 10x (bottom) magnification ................................................................................... 64

Figure 3.21 - Normalized (left) and specific capacity (right) for control electrodes cycled at C/10
discharge rate to 1.1 V using the expanded metal mesh and thin film foil CCs ....................................... 65

Figure 3.22 - Voltage vs. capacity profiles for thin film foil CC and expanded metal mesh CC cathodes.
Cathode mix powder identical in each case (80% EMD, 15% KS44 graphite, 5% BaSO ). ........................ 67
4

Figure 3.23 - Midpoint Voltage vs. Cycle Number for thin film foil CC cells expanded metal mesh CC
cells ........................................................................................................................................................... 68

Figure 3.24 - Powder X-Ray diffraction pattern of SuperC65 carbon black and KS44 graphite ............... 70

Figure 3.25 - 3 idealized representations of EMD-graphite connectivity. Large graphite particle size
(left), intermediate graphite particle size (centre), and small graphite particle size (right). Central
spherical particle represents EMD, with graphite particles surrounding it .............................................. 71

Figure 3.26 - Voltage vs. capacity profiles of 15% KS44 graphite (left), 15% Super C65 carbon black
(right), and 7.5% KS44 Graphite/7.5% Super C65 Carbon black (bottom) ............................................... 72

Figure 3.27 - Capacity vs. cycle of electrodes prepared with 15% KS44 graphite, 15% Super C65 carbon
black and 7.5% of both KS44 graphite and Super C65 carbon black using electrodes prepared with
expanded metal mesh CCs ........................................................................................................................ 73

Figure 3.28 - Capacity vs. Cycle Number for addition of 15, 20, and 25% KS44 graphite at 1.2 and 0.9 V
cut-off potentials ...................................................................................................................................... 75

Figure 3.29 - Normalized (left) and Specific Capacity (right) for control cathode composition (84%
EMD, 16% KS44 graphite) with expanded metal mesh and foil CCs ......................................................... 78
x