Group 07 Kristen Losensky Trenton Wood 1 11-2-12.

Group 07

Kristen Losensky

Trenton Wood

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Reversible Li-O2 Batteries

11-2-12

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Summary: How it Works

• Typical rechargable Li-O2 cell:• Anode (-) is Li metal• Non aqueous Li+ conducting electrolyte• Cathode (+) is porous material

• Key Reaction: • Cathode (+) O2 reduced to form O2

2-

• O22- combines with Li+ from the

electrolyte to form Li2O2 during discharge

http://www.wired.com/gadgetlab/2010/06/mystery-charger-glows-like-iphone-battery-icon/

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Summary: Research Performed• Constructed a Li-O2 cell

• Electrolyte: 0.10 M LiClO4 in dimethyl sulfoxide (DMSO)

• Cathode (+): nanoporous gold (NPG)• Anode (-):Li metal foils (0.38 mm

thick)• Operated in 1 atm O2

• Investigations• Capacity• Reaction(s) and Side Product(s) • Effect of salt/solvent and electrode

substrate• Kinetics

TEM image of NPG

Peng, Zhangquan, Stefan A. Freunberger, Yuhui Chen, and Peter G. Bruce. "A Reversible and Higher-Rate Li-O2 Battery." Science 337 (2012): 563-66. Web. 27 Oct. 2012.

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Introduction: Batteries• “a combination of apparatus for producing a single

electrical effect “• “a group of two or more cells connected together to

furnish electric current; also: a single cell that furnishes electric current “• Miriam Webster

• Primary Battery – can not be recharged

• Secondary Battery – can be recharged

http://www.best-rechargeablebatteries.com/

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Introduction: Primary Batteries

• One-life battery• Production of anions and cations ions produce voltage across the cell

• Discharge rate depends on lifetime and battery material

http://www.jaycar.com.au/images_uploaded/battprim.pdf

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Introduction: Primary Batteries

• Categorized by:Maximum Discharge Rate

Internal Resistance

Temperature

Shelf Life

• Goal:Steady output of current

over working life

http://www.jaycar.com.au/images_uploaded/battprim.pdf

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Introduction: Secondary Batteries

• Rechargeable• Can undergo reverse electrolysis reactions to recharge the cell

• Recharging is done by applying a voltage to the cell, usually AC

http://en.wikipedia.org/wiki/Rechargeable_battery

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Introduction: Secondary Batteries

• Energy output is less than a compared primary cell

• Cost effectiveness weighed against number of cycles a cell can go through

• Secondary batteries tend to have lower shelf lives

http://batteryuniversity.com/learn/article/will_secondary_batteries_replace_primaries

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Basic Principles: Electrochemistry• Voltaic/Galvanic Cells –

spontaneous reaction does electrical work

• Electrolytic Cell – Electricity used to carry out a reaction

http://www.infoswis.com/voltaic-cell/

𝐸𝑐𝑒𝑙𝑙𝑜 =𝐸 h𝑐𝑎𝑡 𝑜𝑑𝑒

𝑜 −𝐸𝑎𝑛𝑜𝑑𝑒𝑜

𝐸=𝐸𝑜−𝑅𝑇𝑛𝐹

ln (𝑄)

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Basic Principles: Infrared Spectroscopy

• Infrared (IR) region • 7.8E-07 m to 1.0E-04 m• Wavenumber = reciprocal wavelength

• Typically use 4000 to 400 cm-1

• Molecules stretch or bend only at specific frequencies

McMurry, John. Organic Chemistry. 7th ed. Mason: Cengage Learning, 2008. Print.

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Basic Principles: Differential Electrochemical Mass Spectroscopy (DEMS)

• Collects electrochemical gaseous products, detects with mass spectroscopy

• Ion current for a species is recorded in parallel to the faradaic electrode current during potential sweep

• Mass Spectrometric Voltammograms

• Detection of volatile electrochemical reaction products Baltruschat, Helmut. "Differential Electrochemical Mass

Spectrometry." J Am Soc Mass Spectrom 15 (2004): 1693-706. Elsevier Inc. Web. 31 Oct. 2012.

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Previous Work• Organic Carbonate Electrolytes

• Decompose irreversibly at the cathode• Produce side products: HCO2Li, CH3CO2Li, [C3H6(CO2Li)3], Li2CO3

• Little or no evidence of Li2O2 formation


• Ethers• More stable to reduced O2

species• Increasing electrolyte

decomposition upon cycling• Do not yield reversible Li2O2

formation/decomposition during cycling FTIR spectra of a discharged NPG cathode in

0.1 LiPF6-DME

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Materials and Methods• Lithium Electrode

• Lithium metal foils (0.38 mm thick) • Submerged in 0.1 M LiClO4-propylene carbonate for 3 days

• Rinsed with DMSO to remove the propylene carbonate

• NPG Electrode• Dealloyed white gold leaf by floating in nitric acid bath for 5 min• Dried by heating under vacuum at 150 °C overnight• Pore size is 30-50 nm

• Carbon Electrodes• Super P:PTFE 8:2 m/m• Coated pastes composed of carbon, binder and 2-propanol onto a

stainless steel mesh current collector (1.5 mg/cm2)• Vacuum dried at 200 °C for 24 hours

http://www.nccp.ru/EN/Li/Li-cat.php

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Results: Capacity• 95% of initial capacity is retained after 100 cycles


Charge/discharge curves (left) and cycling profile (right) for a Li-O2 cell with a 0.1 M LiClO4-DMSO electrolyte and a NPG cathode at a current density of 500 mAg-1

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Results: Reaction(s) and Side Product(s)

• Goal: demonstrate that cathode reaction is formation/ decomposition of Li2O2

• Occurrence and extent of side reactions and side products


Vibrational Spectra of a NPG cathode at the end of discharge and charge in 0.1 M LiClO4-DMSO (A) FTIR and (B) SERS spectra

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Results: Reaction(s) and Side Product(s)

• What is the extent of the side reactions (formation of Li2CO3 and HCO2Li)?

• Do the side reactions increase with more cycling?• Create mixtures of Li2O2 with Li2CO3 and

Li2O2 with HCO2Li

• FTIR Spectra and Calibration Curve

• Fraction of Li2CO2 and HCO2Li <1%

• Li2O2 at discharge >99%, no sign of this value decreasing

• 1H and 13C NMR indicate lack of solution-soluble decomposition products

FTIR Calibration Curve


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Results: DEMS Analysis• Differential Electrochemical Mass Spectrometry (DEMS)

• Analyzes the gases consumed or evolved

• O2 was the only gas detected

• No CO2, SO2, or SO3 detected

• Charge to Mass Ratio: 2e-/O2


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Results: DEMS Analysis

• Presence of only O2 confirms Li2O2 formation during discharge

• Stability of Electrolyte


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Results: Effect of Salt/Solvent and Electrode Substrate

• (1) Replace LiClO4 with LiTFSI • [lithium

bis(trifluoromethanesulfonyl)imide]

• (2) Replace NPG with Carbon Black (Super P)


(a) Discharge/charge curve for 0.1 M LiTFSI-DMSO electrolyte at a current density of 500mAg-1. (b) FTIR

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Results: Effect of Electrode Substrate• Replacement of NPG with Carbon (Super P)

• 15% side reaction products• Higher charging voltage than NPG• Most O2 evolved above 4 V, evolution of CO2


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Results: Effect of Electrode Substrate• Replacement of NPG with Super P infused with nano

particulate gold• Side products are 15% of discharge products• O2 discharge still mostly above 4.0 V


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Results: Kinetics• Desire to increase kinetics of

electrode reaction• Low for charging

• NPG cathode, 0.1 M LiClO4-DMSO• Rate 500 mAg-1 = 5000 mAg-1 for C

electrode of same volume• 1.0 μAcm-2 based on total active

surface area (50m2/g)

• C based electrodes• Rate of 70 mAg-1

• 0.1μAcm-2 based on surface area for super P (60 m2/g)

TEM image of NPG


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Assessment

• Proved reversible cycling based on Li2O2

• Capacity and Purity are retained• Salt/Solvent choice do not have a significant effect• NPG serves as a better electrode than Carbon or Carbon

with nano particulate gold

tradekorea.comhttp://nevada-outback-gems.com/prospect/gold_specimen/Natural_gold2.htm

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Further Research• Nanoporous Gold electrodes are not practical

• Gold-coated Carbon• Explore other materials

• Effect of pore size on the cell

• Effect of Pressure on the cell

http://www.unav.es/grado/chemistry/

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References (Pictures)1. http://www.wired.com/gadgetlab/2010/06/mystery-charger-

glows-like-iphone-battery-icon/2. tradekorea.com3. http://nevada-outback-gems.com/prospect/gold_specimen/

Natural_gold2.htm4. http://www.unav.es/grado/chemistry/5. http://www.nccp.ru/EN/Li/Li-cat.php6. http://www.infoswis.com/voltaic-cell/7. http://www.best-rechargeablebatteries.com/8. http://www.jaycar.com.au/images_uploaded/battprim.pdf9. http://en.wikipedia.org/wiki/Rechargeable_battery10. http://batteryuniversity.com/learn/article/

will_secondary_batteries_replace_primaries

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References1. Peng, Zhangquan, Stefan A. Freunberger, Yuhui Chen, and

Peter G. Bruce. "A Reversible and Higher-Rate Li-O2 Battery." Science 337 (2012): 563-66. Web. 27 Oct. 2012.

2. McMurry, John. Organic Chemistry. 7th ed. Mason: Cengage Learning, 2008. Print.

3. Baltruschat, Helmut. "Differential Electrochemical Mass Spectrometry." J Am Soc Mass Spectrom 15 (2004): 1693-706. Elsevier Inc. Web. 31 Oct. 2012.

4. Kotz, John C., Paul M. Treichel, and John R. Townsend. Chemistry & Chemical Reactivity. 7th ed. Belmont: Brooks/Cole Cengage Learning, 2009. Print.

5. "Battery." Merriam-Webster. Merriam-Webster, 2012. Web. 31 Oct. 2012. <http://www.merriam-webster.com/dictionary/battery>.

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References

6. "Primary Cells & Batteries." Jaycar Electronics, 2001. Web. 31 Oct. 2012.

7. "How to Select Secondary (Rechargeable) Batteries." Global Spec Electronics. N.p., 2012. Web. 31 Oct. 2012.

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QUESTIONS?

Group 07 Kristen Losensky Trenton Wood 1 11-2-12.

Documents

Transcript of Group 07 Kristen Losensky Trenton Wood 1 11-2-12.