Transcript Eco-Materials group

空氣電池的開發與應用
Development and Application of Air-battery
Department of Materials Engineering
Speaker : Prof. Chao-Ming Huang (K. S. U.)
Dec.13. 2014
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Outline
Introduction
Metal-air batteries
Li-Air battery
Zn-Air battery
Conclusions
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2013 Global energy consumption
87% !
From:http://euanmearns.com/global-energy-trends-bp-statistical-review-2014/
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Statistic of World Energy
155
65.1
40.6
Petroleum
From:http:/ BP Statistical Review of World Energy /
Natural Gas
Coal
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What is a hydrogen fuel cell ?
•Hydrogen fuel cells (HFCs) are a type of
electrochemical cell.
•HFCs generate electricity by reduction and
oxidation reactions within the cell.
•They use three main components, a fuel, an
oxidant and an electrolyte.
•HFCs operate like batteries, although they
require external fuel.
•HFCs are a thermodynamically open system.
•HFCs use hydrogen as a fuel, oxygen as an oxidant,
a proton exchange membrane as an electrolyte, and
emit only water as waste.
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Different type of fuel cell comparsion
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How do they work?
•
Fuel (H2) is first transported to the
anode of the cell
•
Fuel undergoes the anode reaction
•
Anode reaction splits the fuel into
H+ (a proton) and e-
•
Protons pass through the
electrolyte to the cathode
•
Electrons can not pass through the
electrolyte, and must travel
through an external circuit which
creates a usable electric current
•
Protons and electrons reach the
cathode, and undergo the cathode
reaction
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Zn-Air Chemistry
• Schematic representation of Zn-air cell
operation:
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Zn-Air Applications
•
Commercial, primary Zn-air batteries have been used for many years:
– Initially used as large batteries for applications such as railroad signaling,
remote communications, and ocean navigational units requiring long term, low
rate discharge.
– With the development of thin electrodes, used in small, high capacity primary
cells, such as for hearing aids, small electronics, and medical devices.
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Refuelable Zn-Air Cells
• Santa Barbara Municipal Transit District “Downtown
Waterfront Electric Shuttle”
• Powered by refuelable Zn-air cells.
• Road test underscored potential of such vehicles.
– 250 mile range between refueling
– Rapid refueling (10 minutes)
– Highway safe acceleration
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Refuelable Zn-Air cells
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Summary
• Primary Zn-air batteries have been very successful commercially.
• To take the technology to the next level, i.e, developing secondary,
electrically rechargeable batteries, or using Zn-air technologies for vehicle
propulsion, significant challenges must still be overcome:
– Understand the chemistry of the zincate anion in an alkaline solution.
– Develop stable bifunctional catalysts for both the oxygen reduction
reaction and oxygen evolution reaction.
– The air electrode should be optimized to reduce internal resistance.
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Current Battery Outlook
• Metal-air batteries have attracted much attention
recently as a possible alternative, due to their
extremely high energy density compared to that of
other rechargeable batteries:
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Why Li-air ?
• Extremely high specific capacity of Li anode material (3842 mAh g-1 for lithium,
vs. 815 mAh g-1 for Zinc)
• The couple voltage of Li-O2 in alkaline electrolytes is 2.91 V (compared to 1.65
for Zn-O2)
• The Li-air battery, when fully developed, could have practical specific energies of
300 Wh kg-1
• Li-air cell electrically rechargeable
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Different type of battery comparsion
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Secondary Li-Air Cells
• How are Li-air cells rechargeable?
Li(s) → Li+ + e(anode reaction)
Li+ + ½O2 + e- → ½Li2O2
(cathode reaction)
Li+ + e- + ¼O2 → ½Li2O
(cathode reaction)
• In 2006, Bruce et al. demonstrated that Li2O2 is formed on charging and
decomposes according to the reaction below:
Li2O2 → O2 + 2Li+ + 2e-
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Li - air Architectures
From:锂空气电池多孔碳电极材料的制备及性能研究
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Configuration of Li - air
The critical differences between Li-ion and Li-Air are:
 Li-Air battery is an open system, because of oxygen is obtained from air
Anode:
Cathode:
catalyst
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MnOx based catalysts
•Catalysts will not only affect ORR & OER potential, but they also influence the specific
capacity
 MnO2 is the most common ORR catalyst for metal-air battery, because it is cheap & stable;
Besides, their ORR-catalytic activity (ORR poential ~ 2.6 V) can compare with most efficient
catalyst—Pt( 2.6 V)
 The Bruce group had investigated various MnOx catalysts(α,β,γ, -MnO2& Mn2O3, Mn3O4)
Nano--structure has
higher capacity, duo
to high surface area
Capacity can achieve ~3000 mAh/g
Discharge @ a rate of 70 mA/cm2 & 1 atm O2
The structure of αMnO2 possesses 2x2
tunnels
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Air Electrode Requirements
• Cathode must be able to sustain an oxygen reduction reaction
(and oxidation if battery is rechargeable).
• Cathode must be highly porous.
• Catalysts are typically incorporated into the carbon layer.
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Factors that affect performance
• Most metals are unstable in water and react with the electrolyte to corrode the
metal, resulting in self-discharge.
• Electrode carbonation: Absorption of CO2 (since the cell is an open system),
results in crystallization of carbonate in the air electrode, clogging pores and
decreasing performance.
• Water transpiration: Movement of water vapor either into or out of the cell.
– Excessive water loss can lead to drying of the cell and premature failure.
– Excessive gain of water can dilute the electrolyte.
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LaMnO3 Perovskite system
oxygen reduction reaction (ORR)
good redox properties,
thermochemical stability,
tunable catalytic performance.
P123 (Triblock Copolymer)
Template
Journal of the Taiwan Institute of Chemical Engineers
45 (2014) 2334–2339 (SCI, IF = 2.637)
22
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mesoporous
macroporous
irregular
↓
foamy structure
↓
very fine particles
P123. ↑
specific surface area. ↑
pore volume. ↑
23
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Discharge voltages ↑
LMP-20, 1.158V
LMP-10, 1.158V
LMP-6, 1.140V
LMP-2, 1.128V
LM, 1.090V
25 mA/cm2
600-s/cycle
↑ cycling stability
↑ discharge voltage 1.090 V→1.158 V
pure phase. LaMnO3
large surface area. 2.8X
high pore volume. 4X
Energy density = 885 W h/kg(Zn consumption)
current density =25 mA/cm2
discharge voltage = 1.18 V
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• Zinc Air Battery
• Cathode : Catalysts
• Anode : Zinc
• Electrolyte : NaOH, KOH
Discharge
(Oxygen Reduction Reaction, ORR)
Charge
(Oxygen Evolution Reaction, OER)
PS: potentiostatic, 定電壓
GS: galvanostatic, 定電流
CV: cyclic voltammogram, 循環伏安
25
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2.0
1.8
Potential/V
1.6
1.4
1.2
1.0
0.8
0
1000 2000 3000 4000
246000
248000
250000
time/s
Ch-dis: 10mA
Time: 5 min
庫倫效率=60%
Pure-SS
star-MnO2/SS
Element
CK
OK
Na K
SK
Cr K
Mn K
Fe K
Weight%
4.99
32.15
5.04
3.30
3.14
41.54
9.84
Totals
100.00
star-MnO2/SS
10-6
(μ m)
10-5
10-4
10-3
26
(mm)
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Global air battery prediction
250
201.42
million dollars
200
176.3
154.31
150
135.06
118.22
103.47
100
90.57
50
0
2014
2015
2016
2017
2018
2019
2020
Year
From: 北京國信博研信息中心
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New Tesla Patent: 400-Mile Battery
Pack Using Metal-Air & Lithium-Ion
Batteries
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Air Battery System
1)
Zinc
2)
Aluminium
3)
Lithium
From: 北京國信博研信息中心
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New Tesla Patent: Electric Vehicle Extended Range
Hybrid Battery Pack System
▪ Patent : US 20130181511
Abstract
▪ A power source comprised of a first battery pack (e.g., a
non-metal-air battery pack) and a second battery pack (e.g.,
a metal-air battery pack) is provided, wherein the second
battery pack is used when the user selects an extended range
mode of operation. Minimizing use of the second battery
pack prevents it from undergoing unnecessary, and
potentially lifetime limiting, charge cycles.
From:http://www.google.com/patents/US20130181511
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Conclusions
• Metal-air batteries offer great benefits if they can be
harnessed to their fullest potential.
• Recap of Zn-air vs. Li-air:
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