Biological Engineering

Electrochemistry & Virus-Templated Electrodes

F. John BurpoBiomolecular Materials Laboratory

Massachusetts Institute of Technology

November 30, 2010

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Electrochemistry Review

Lithium Rechargeable Batteries

Battery Testing

Outline

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1970: Design Choice

Blue Pill: Increase CPU transistor chip density x2,000,000

Red Pill: Increase rechargeable

battery capacity x4

Imagine

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Electrochemistry Basics

Cu Zn

e-e-

(-)ions(+)ions –+

Cu2+(aq) +2e- → Cu(s) +0.337 V Zn(s) → Zn2+(aq) +2e- +0.763 V

Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s) 1.100 V

I

Salt Bridge

I

Capacity = I∙time

V

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Standard reduction potentialsHalf reaction Eo, V

F2 (g) + 2H+ + e- 2HF (aq) 3.053Ce4+ + e- Ce3+ (in 1M HCl) 1.280O2 (g) + 4H+ + 4e- 2H2O (l) 1.229Ag+ + e- Ag (s) 0.799

Cu2+ + 2e- Cu(s) 0.3402H+ + 2e- H2 (g) 0.000Pb2+ + 2e- Pb (s) -0.125 Fe2+ + 2e- Fe (s) -0.440Zn2+ + 2e- Zn (s) -0.763Al3+ + 3e- Al (s) -1.676

Li+ + e- Li(s) -3.04

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Anode: Zn(s) Zn2+(aq) + 2e- Eo = +0.76 V

What is Eo for the Zn/Cu cell?

Eocell = Eo

cathode - Eoanode= 0.34 – (-0.76) = +1.10 V

Net: Cu2+(aq) + Zn(s) Zn2+(aq) + Cu(s)

Cathode: Cu2+(aq) + 2e- Cu(s) Eo = +0.34 V

Eocell = Eo

cathode ̶ Eoanode

Products ̶̶ ReactantsProduct gets electron

Reactant gives electron

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• For a reactant-favored reaction - Electrolytic cell: Electric current chemistry

Reactants Products

DGo > 0 and so Eo < 0 (Eo is negative)

• For a product-favored reaction – Galvanic cell: Chemistry electric current

Reactants Products

DGo < 0 and so Eo > 0 (Eo is positive)

Eo and DGo DGo = - n F Eo

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When not in the standard state (Nernst Equation)

DG = - nFE DGo = - nFEo DG = DG0 + 2.303 RT log Q

E = E0 - (RT/nF) ln Q aA + bB cC + dD

• At standard state temperature, Nernst equation

ba

dc

BADC

][][][][log

n 0.0592 - E E 0

Q is the reaction quotient, or the ratio of the activities of products to reactants

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= Li+

= LiPF6

Charged state

LiC6 (graphite anode)

Li2O/Coo (cobalt oxide anode)

Anod

e Cathode

FePO4 cathode

CoO2 cathode

e- e-

C (graphite anode)

Co3O4 (cobalt oxide anode)LiFePO4 cathode

LiCoO2 cathode

Discharged stateDischarging

Lithium Rechargeable BatteriesHow They Work

Courtesy Dr. Mark Allen

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Energy Density & Capacity

Tarascon, Nature 414, 359-367 (2001)

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Energy Density & Capacity

Tarascon, Nature 414, 359-367 (2001)

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Lithium plating and dendrites

Xu, K., Chemical Reviews, 2004 4303-4417Tarascon, J.M. & Armand, M., Nature, 414, (2001)

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Chemistries of electrodes

• Most common electrode system is that of LiCoO2 and graphite

charge2 1 2discharge xLiCoO Li CoO xLi xe

charge2 1 2 6discharge

6 x xLiCoO C Li CoO Li C

discharge6charge

6 xxLi xe C Li C

3.8-3.9 V vs. Li

0.1 V vs. Li

3.7 V total

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Battery Form Factors

Tarascon, Nature 414, 359-367 (2001)

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Ubiquitous device demand for energy storage. Need for flexible, conformable, and microbatteries. Micro Power Demand: MEMS devices, medical implants, remote sensors, smart cards, and energy harvesting devices.

Demand & Capacity

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Battery Design Parameters“Design Landscape”

Pressure

Li Dendritic Growth

Cycling Life

Separator permeability

Overpotential

Charge/Discharge Rates

Energy DensityPower Density

Electrode Potentials

Solid Electrolyte Interface

Electrolyte StabilityVolume Swelling

Capacity

Background Objectives Research Design Results

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Where to go next?

Background Objectives Research Design Results

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Specthrie, J Mol Biol. 228(3):720-4 (1992)

M. Russel, B. Blaber.

M13 Bacteriophage

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M13 Bacteriophage

Flynn, Acta Materialia 51, 5867-5880 (2003)(Marvin, J. Mol. Biol. 355, 294–309 (2006)

Background Objectives Research Design Results

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Evolving the Battery

Courtesy of Angela Belcher

Background Model Aims Experiments Future

Tarascon, Nature 414, 359-367 (2001)

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Bio-Battery ApplicationsUAS Systems

Soldier Load

Plug-in HybridLab on a Chip

Background Objectives Research Design Results

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Synthesizing Electrodes

Mix Nanowires with carbon and organic binder

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Au or Ag : capable of

alloying with Li up to

AgLi9 and Au4Li15 at very

negative potential

Taillades, 2002, Sold State Ionicshttp://www.asminternational.org/

Alloy forming anodes for Lithium ion batteries

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Pure Au viral nanowires

Plateaus: 0.2 and 0.1 V/discharge0.2 and 0.45V/charge

Capacity from 2nd cycle501 mAh/g [AuLi3.69]Diameter: ~40 nm, free surface

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Coin Cell Assembly

Lower Assembly

Upper Assembly

Lithium (s)

Steel Spacer

Copper Foil – Current CollectorElectrode

2 x Polymer Separators

PlasticO-Ring

ElectrolyteElectrolyte

Background Design Results Future

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Capacity Calculation

8 95484 sec 1 1000 11 3600sec 1 240.8

e X A hour mA moleX X Xmole Amp g

= 881 mAh/g

arg 03 4 2arg

8 8 4 3Disch e

Ch eLi Co O e Li O Co

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Calculating capacity for Gold Anodedischarge

charge xAu xLi AuLi Discharge

4 15Charge4Au+15Li 15 Au Lie

Determine the active mass, not everything in the electrode is redox active

2 0.7 0.8 1.12mg X X mg active material

Example: a 2 mg electrode with 20% inactive material (super P and PTFE binder)

1 445.97 11.12 0.4991000 1 1

g mAhmg X X X mAmg g hr

In order to discharge this electrode over one hour, apply -0.499 mA

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Battery Testing16 channels for testing batteries

8 coin cell

testers

Celltest program for measurement and

analysis

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Au0.9Ag0.1

Discharge/charge curves from the first two cycles

Au0.5Ag0.5

Au0.67Ag0.33

2nd cycle : 499mAh/g459mAh/g

Au0.9Ag0.1

Curve shape similar with AuCapacity at 2nd cycle : 439mAh/g

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The Ragone Plot

Gasoline energy density ~12 kWh/kg and nuclear fission yields ~ 25 billion Wh/kg

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So What Else Can the Virus Do?

gIII, gVIgVIIIgVII, gIX

Batteries Electrochromics Solar Cells

Fuel Cells Electronics MedicineCarbon Capture

H2O Splitting

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Questions ???

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Cathode Materials