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Advanced Materials for Multi-Electron Redox Flow Batteries

Monday, September 26, 2016 Harry Pratt, Cy Fujimoto, Leo Small, Travis Anderson

Project Overview Problem: Cost competitive ionic liquids have high viscosities but are promising for higher energy density redox flow batteries due to higher metal concentrations and wider voltage windows.

Approach: Couple earth-abundant electrolytes with commercial and custom membranes and rapidly test and tune in an iterative fashion using laboratory-scale cell designs.

Energy DensityRFB ≈ ½nFVcellcactive EDAQ = ½1F1.5cell2active = 1.5F

EDIL = ½2F2cell3active = 6.0F Potential for four-fold improvement

2

Increased renewables penetration on the grid

+MetIL

MetIL–

Membrane Ion Content

Membranes contain a polyphenylene backbone with pendant ionic groups; ionic content was varied qualitatively high, medium, and low.

C

C

*m*

m

CCl

O

AlCl3

O

O

CH2Cl2

Br

Br

Br

NMe3

C

C

*m

O

O

Me3N

Me3N

Br

Br

3

Small, Pratt, Fujimoto, and Anderson, J. Electrochem. Soc., 2016, A5106.

Post Cycling Studies

4

Fc Fc+ + e–

Cu+ Cu2+ + e–

Catholyte

Anolyte

• The decreased electrochemical yield was

investigated by (1) cycling rate effects; (2) crossover measurements; (3) impedance; (4) membrane stability.

• The CV as well as the overlay of the static and cycled data show that crossover was responsible for the lowered yield.

Small, Pratt, Fujimoto, and Anderson, J. Electrochem. Soc., 2016, A5106.

Chemical Stability

5

Small, Pratt, Fujimoto, and Anderson, J. Electrochem. Soc., 2016, A5106.

100 μm 100 μm

10 μm 10 μm

A B

C D

Before Cycling

After Cycling

• SEM and EDS data suggest that there was some decomposition of the ionic liquid.

• The increased resistance after cycling is attributed to the formation of a film on the surface of the membrane.

Membrane Before Cycling

Membrane After Cycling

Supporting Electrolyte

Infrared data shows membrane is stable.

Recently a number of groundbreaking solutions to higher energy density have appeared.

“Lightest Organic Radical Cation…” Huang, Wang, et. al, Science Reports, 2016

“Voltage Clustering in Redox-Active Ligands…” Zarkesh, Anstey, et. al, Dalton Trans., 2016

“Alkaline Quinone Flow Battery” Lin, Aziz, et. al, Science, 2016

25. N. H. Schlieben et al., J. Mol. Biol. 349, 801–813

(2005).

26. K. Tauber et al., Chemistry 19, 4030–4035 (2013).

27. See supplementary materials on Science Online.

28. A. C. Price, Y.-M. Zhang, C. O. Rock, S. W. White, Structure 12,

417–428 (2004).

29. The Ph-AmDHtolerates different buffers well (i.e., ammonium

chloride, formate, borate, citrate, acetate, oxalate). However, the

homotetrameric LBv-ADHs contains two Mg2+ centers; therefore,

strong chelators such as oxalate, citrate, and acetate must be

avoided as buffer salts. Removal of theseMg2+ ions inactivates the

enzyme (32).

30. B. R. Bommarius, M. Schürmann, A. S. Bommarius, Chem.

Commun. 50, 14953–14955 (2014).

31. R. Cannio, M. Rossi, S. Bartolucci, Eur. J. Biochem. 222,

345–352 (1994).

32. K. Niefind, J. Müller, B. Riebel, W. Hummel, D. Schomburg,

J. Mol. Biol. 327, 317–328 (2003).

ACK N OWLEDGM EN TS

The research leading to these results received funding from the

European Union’s Seventh Framework Programme FP7/ 2007-2013

under grant agreement 266025 (BIONEXGEN). The project leading

to this application has received funding from the European

Research Council under the European Union’s Horizon 2020

research and innovation program (grant agreement no. 638271,

BioSusAmin). T.K. and N.S.S. received funding from UK

Biotechnology and Biological Sciences Research Council (BBSRC;

BB/ K0017802/ 1). N.J.T. is grateful to the Royal Society for a

Wolfson Research Merit Award. Some aspects of the results

reported here are the subject of a provisional patent application.

Author contributions: F.G.M. and N.J.T. conceived the project and

wrote the manuscript; F.G.M. planned the experiments, expressed

and purified the AmDHs, performed the biocatalytic reactions, and

analyzed the data; T.K. performed the gene cloning of all AmDHs

and purified the ADHs; N.S.S. and M.B. provided intellectual and

technical support; and M.B. and BASF provided the ADHs. We

thank R. Heath for a preliminary kinetic assay of the Ph-AmDH.

SUPPLEMENTARY MATERIALS

www.sciencemag.org/ content/ 349/ 6255/ 1525/ suppl/ DC1

Materials and Methods

Figs. S1 to S12

Tables S1to S20

References (33–36)

30 June 2015; accepted 14 August 2015

10.1126/ science.aac9283

BATTERIES

Alkaline quinone flow batteryK aixiang Lin,1 Qing Chen,2 M ichael R. Gerhardt,2 Liuchuan Tong,1 Sang Bok K im,1

Louise Eisenach,3 Alvaro W . Val le,3 David H ardee,1 Roy G. Gordon,1,2*

M ichael J. Aziz,2* M ichael P. M arshak1,2*

Storage of photovoltaic and wind electricity in batteries could solve the mismatch problem

between the intermittent supply of these renewable resources and variable demand. Flow

batteries permit more economical long-durat ion discharge than solid-electrode batteries by

using liquid electrolytes stored outside of the battery. We report an alkaline flow battery based

on redox-act ive organic molecules that are composed ent irely of Earth-abundant elements

and are nontoxic, nonflammable, and safe for use in residential and commercial environments.

The battery operates efficiently with high power density near room temperature.These results

demonstrate the stability and performance of redox-active organic molecules in alkaline

flow batteries, potentially enabling cost-effect ive stationary storage of renewable energy.

The cost of photovoltaic (PV) and wind elec-

tricity hasdropped so much that oneof the

largest barriers to getting most of our elec-

tricity from theserenewablesources is their

intermittency(1–3).Batteriesprovideameans

to storeelectrical energy; however, traditional, en-

closed batteriesmaintain dischargeat peak power

for far too short a duration to adequately regulate

wind or solar power output (1,2). In contrast, flow

batteries can independently scale the power and

energy components of the system by storing the

electro-activespeciesoutsidethebatterycontainer

itself (3–5). In a flow battery, the power is gen-

erated in a device resembling a fuel cell, which

containselectrodesseparated byan ion-permeable

membrane. Liquid solutions of redox-active spe-

cies are pumped into the cell, where they can be

charged and discharged, beforebeing returned to

storage in an external storage tank. Scaling the

amount of energy to be stored thus involves sim-

ply making larger tanks (Fig. 1A). Existing flow

batteries are based on metal ions in acidic solu-

tion, but challengeswith corrosivity,hydrogen evo-

lution, kinetics, materialscost and abundance, and

efficiency thusfar haveprevented large-scalecom-

mercialization. The use of anthraquinones in an

acidic aqueous flow battery can dramatically

SCI EN CE sciencemag.org 25 SEPTEMBER 2015 • VOL 349 I SSUE 6255 152 9

Fig. 1. Cyclic voltammetry of elect rolyte and cell schemat ic. (A) Schematic

of cell in charge mode. Cartoon on top of the cell represents sources of

electrical energy from wind and solar. Curved arrows indicate direction of

electron flow, and white arrows indicate electrolyte solution flow. Blue ar-

row indicates migration of cations across the membrane. Essential com-

ponents of electrochemical cells are labeled with color-coded lines and

text. The molecular structures of oxidized and reduced species are shown

on corresponding reservoirs. (B) Cyclic voltammogram of 2 mM 2,6-DHAQ

(dark cyan curve) and ferrocyanide (gold curve) scanned at 100 mV/ s on

glassy carbon electrode; arrows indicate scan direction. Dotted line rep-

resents CV of 1 M KOH background scanned at 100 mV/ s on graphite foil

electrode.

1Department of Chemistry and Chemical Biology, Harvard

University, 12 Oxford Street, Cambridge, MA 02138, USA.2Harvard John A. Paulson School of Engineering and Applied

Sciences, 29 Oxford Street, Cambridge, MA 02138, USA.3Harvard College, Cambridge, MA 02138, USA.

*Corresponding author. E-mail: aziz@seas.harvard.edu (M.J.A.);

gordon@chemistry.harvard.edu (R.G.G.); michael.marshak@colorado.

edu (M.P.M.)

RESEARCH | REPORTS

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“High-energy density non-aqueous …” Jia et. al, Science Adv., 2016

Hybrid Nafion-PVDF Li-conducting membrane

Increasing Energy Density

6

Can we make the solvent and supporting electrolyte “filler” electrochemically active?

Start with Sandia’s MetILs and replace increasing amounts of “filler” with redox active compounds (I-, Fc) until it becomes impractical.

Replace 1st OTf-

with redox-active I- Single liquid

phase at 25 °C

Replace 2nd OTf-

with redox-active I- Phase

separation

Couple FcCOOH to 1st ligand

Tmelt ~70 °C

Couple FcCOOH to 2nd ligand

Tmelt >100 °C

Tmelt ~60 °C Single liquid

phase

Increasing Energy Density–Strategy

7

Fe-MetIL Fe-MetIL3

Redox activity added to the ligands and anions

2.8 M redox-active e-

7.4 M redox-active e-

Fe2+ Fe3+ + e- Fe2+ Fe3+ + e-

Fc Fc+ + e- 3I- I3

- + 2e-

MetILs3

8

Fe2+ and Fc-ligand shift to lower potentials when MetIL forms

Square Wave Voltammetry

Ethanolamine Peak

3354 (N-H) 2860 (O-H)

Fe-MetIL 7 20

Fe-MetIL3 8 15

Ethanolamine O-H and N-H IR peaks shift upon complexation

Infrared Spectroscopy

O-H N-H

MetILs3 Characterization

9

MetIL3

Membrane: Fumasep FAP-PK (anion exchange)

cobaltocene

200 mM 0.5 M LiNTf2 in PC 5 mA/cm2

Cc Cc+ + e- Fe3+ + e-

Fe3+

Fc+ + e- Fc

I3- + 2e-

3I-

100 mM 0.5 M LiNTf2 in PC 5 mA/cm2

Cell shows good cyclability after initial capacity loss.

MetILs3 Initial Flow Cell Studies

10

Polyoxometalate (POM) cathode: Na3PW12O40 PW12O40

3- + 24e- PW12O40

27-

POM

Potential

Cu

rre

nt

POM +mediator -mediator

11

Mediated Flow Batteries

• energy stored in easily exchangeable canisters of material

• mediators serve as redox shuttles between electrodes and canisters

• polyoxometalates may be substituted with traditional lithium intercalation materials

Sandia Laboratory Directed Research and Development

12

Summary and Acknowledgements

• Diels Alder polyphenylene membranes with tunable ion content provide an alternative to commercial systems.

• MetILs3 utilizes electrolyte “filler” to increase theoretical energy density 3X from 190 to 620 Wh/L over MetILs.

• In 2016 the team published two new papers including one featured on the cover of Journal of Materials Chemistry A and was granted one new patent.

The authors acknowledge the Department of Energy, Office of Electricity Delivery and Energy Reliability for funding and in particular Dr. Imre Gyuk, Energy Storage Program Manger, for his dedication and support to the entire energy storage industry.

OFFICE OF ELECTRICITY DELIVERY & ENERGY RELIABILITY