Group 07 Kristen Losensky Trenton Wood

Summary: How it Works Typical rechargable Li-O 2 cell: Anode (-) is Li metal Non aqueous Li + conducting electrolyte Cathode (+) is porous material Key Reaction: Cathode (+) O 2 reduced to form O 2 2- O 2 2- combines with Li + from the electrolyte to form Li 2 O 2 during discharge 2

Summary: Research Performed Constructed a Li-O 2 cell Electrolyte: 0.10 M LiClO 4 in dimethyl sulfoxide (DMSO) Cathode (+): nanoporous gold (NPG) Anode (-):Li metal foils (0.38 mm thick) Operated in 1 atm O 2 Investigations Capacity Reaction(s) and Side Product(s) Effect of salt/solvent and electrode substrate Kinetics 3 TEM image of NPG Peng, Zhangquan, Stefan A. Freunberger, Yuhui Chen, and Peter G. Bruce. "A Reversible and Higher-Rate Li-O 2 Battery." Science 337 (2012): Web. 27 Oct

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 4

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 5

Introduction: Primary Batteries Categorized by: Maximum Discharge Rate Internal Resistance Temperature Shelf Life Goal: Steady output of current over working life 6

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 7

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 8 _batteries_replace_primaries

Basic Principles: Electrochemistry Voltaic/Galvanic Cells – spontaneous reaction does electrical work Electrolytic Cell – Electricity used to carry out a reaction 9

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

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 11 Baltruschat, Helmut. "Differential Electrochemical Mass Spectrometry." J Am Soc Mass Spectrom 15 (2004): Elsevier Inc. Web. 31 Oct

Previous Work Organic Carbonate Electrolytes Decompose irreversibly at the cathode Produce side products: HCO 2 Li, CH 3 CO 2 Li, [C 3 H 6 (CO 2 Li) 3 ], Li 2 CO 3 Little or no evidence of Li 2 O 2 formation 12 Peng, Zhangquan, Stefan A. Freunberger, Yuhui Chen, and Peter G. Bruce. "A Reversible and Higher-Rate Li- O 2 Battery." Science 337 (2012): Web. 27 Oct Ethers More stable to reduced O 2 species Increasing electrolyte decomposition upon cycling Do not yield reversible Li 2 O 2 formation/decomposition during cycling FTIR spectra of a discharged NPG cathode in 0.1 LiPF 6 -DME

Materials and Methods Lithium Electrode Lithium metal foils (0.38 mm thick) Submerged in 0.1 M LiClO 4 -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 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/cm 2 ) Vacuum dried at 200 °C for 24 hours 13

Results: Capacity 95% of initial capacity is retained after 100 cycles 14 Peng, Zhangquan, Stefan A. Freunberger, Yuhui Chen, and Peter G. Bruce. "A Reversible and Higher-Rate Li-O 2 Battery." Science 337 (2012): Web. 27 Oct Charge/discharge curves (left) and cycling profile (right) for a Li-O 2 cell with a 0.1 M LiClO 4 -DMSO electrolyte and a NPG cathode at a current density of 500 mAg -1

Results: Reaction(s) and Side Product(s) Goal: demonstrate that cathode reaction is formation/ decomposition of Li 2 O 2 Occurrence and extent of side reactions and side products 15 Peng, Zhangquan, Stefan A. Freunberger, Yuhui Chen, and Peter G. Bruce. "A Reversible and Higher-Rate Li-O 2 Battery." Science 337 (2012): Web. 27 Oct Vibrational Spectra of a NPG cathode at the end of discharge and charge in 0.1 M LiClO 4 -DMSO (A) FTIR and (B) SERS spectra

Results: Reaction(s) and Side Product(s) What is the extent of the side reactions (formation of Li 2 CO 3 and HCO 2 Li)? Do the side reactions increase with more cycling? Create mixtures of Li 2 O 2 with Li 2 CO 3 and Li 2 O 2 with HCO 2 Li FTIR Spectra and Calibration Curve Fraction of Li 2 CO 2 and HCO 2 Li <1% Li 2 O 2 at discharge >99%, no sign of this value decreasing 1H and 13C NMR indicate lack of solution-soluble decomposition products 16 FTIR Calibration Curve Peng, Zhangquan, Stefan A. Freunberger, Yuhui Chen, and Peter G. Bruce. "A Reversible and Higher-Rate Li-O 2 Battery." Science 337 (2012): Web. 27 Oct

Results: DEMS Analysis Differential Electrochemical Mass Spectrometry (DEMS) Analyzes the gases consumed or evolved O 2 was the only gas detected No CO 2, SO 2, or SO 3 detected Charge to Mass Ratio: 2e - /O 2 17 Peng, Zhangquan, Stefan A. Freunberger, Yuhui Chen, and Peter G. Bruce. "A Reversible and Higher-Rate Li-O 2 Battery." Science 337 (2012): Web. 27 Oct

Results: DEMS Analysis Presence of only O 2 confirms Li 2 O 2 formation during discharge Stability of Electrolyte 18 Peng, Zhangquan, Stefan A. Freunberger, Yuhui Chen, and Peter G. Bruce. "A Reversible and Higher-Rate Li- O 2 Battery." Science 337 (2012): Web. 27 Oct

Results: Effect of Salt/Solvent and Electrode Substrate (1) Replace LiClO 4 with LiTFSI [lithium bis(trifluoromethanesulfonyl)imide] (2) Replace NPG with Carbon Black (Super P) 19 Peng, Zhangquan, Stefan A. Freunberger, Yuhui Chen, and Peter G. Bruce. "A Reversible and Higher-Rate Li-O 2 Battery." Science 337 (2012): Web. 27 Oct (a) Discharge/charge curve for 0.1 M LiTFSI-DMSO electrolyte at a current density of 500mAg-1. (b) FTIR

Results: Effect of Electrode Substrate Replacement of NPG with Carbon (Super P) 15% side reaction products Higher charging voltage than NPG Most O 2 evolved above 4 V, evolution of CO 2 20 Peng, Zhangquan, Stefan A. Freunberger, Yuhui Chen, and Peter G. Bruce. "A Reversible and Higher-Rate Li-O 2 Battery." Science 337 (2012): Web. 27 Oct

Results: Effect of Electrode Substrate Replacement of NPG with Super P infused with nano particulate gold Side products are 15% of discharge products O 2 discharge still mostly above 4.0 V 21 Peng, Zhangquan, Stefan A. Freunberger, Yuhui Chen, and Peter G. Bruce. "A Reversible and Higher-Rate Li-O 2 Battery." Science 337 (2012): Web. 27 Oct

Results: Kinetics Desire to increase kinetics of electrode reaction Low for charging NPG cathode, 0.1 M LiClO 4 - DMSO Rate 500 mAg -1 = 5000 mAg -1 for C electrode of same volume 1.0 μAcm -2 based on total active surface area (50m 2 /g) C based electrodes Rate of 70 mAg μAcm -2 based on surface area for super P (60 m 2 /g) 22 TEM image of NPG Peng, Zhangquan, Stefan A. Freunberger, Yuhui Chen, and Peter G. Bruce. "A Reversible and Higher-Rate Li-O 2 Battery." Science 337 (2012): Web. 27 Oct

Assessment Proved reversible cycling based on Li 2 O 2 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 23 tradekorea.com

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 24

References (Pictures) 1. glows-like-iphone-battery-icon/ 2. tradekorea.com 3. gems.com/prospect/gold_specimen/Natural_gold2.htm ries_replace_primaries 25

References 1. Peng, Zhangquan, Stefan A. Freunberger, Yuhui Chen, and Peter G. Bruce. "A Reversible and Higher-Rate Li-O 2 Battery." Science 337 (2012): Web. 27 Oct McMurry, John. Organic Chemistry. 7th ed. Mason: Cengage Learning, Print. 3. Baltruschat, Helmut. "Differential Electrochemical Mass Spectrometry." J Am Soc Mass Spectrom 15 (2004): Elsevier Inc. Web. 31 Oct Kotz, John C., Paul M. Treichel, and John R. Townsend. Chemistry & Chemical Reactivity. 7th ed. Belmont: Brooks/Cole Cengage Learning, Print. 5. "Battery." Merriam-Webster. Merriam-Webster, Web. 31 Oct

References 6. "Primary Cells & Batteries." Jaycar Electronics, Web. 31 Oct "How to Select Secondary (Rechargeable) Batteries." Global Spec Electronics. N.p., Web. 31 Oct

QUESTIONS? 28