Pushing the Efficiency Limits of and Storage - Energy...Pushing the Efficiency Limits of Energy Conversion and Storage Through Rational Materials Design. ALS ChuehLab.stanford.edu

Will ChuehMaterials Science & Engineering ∙ Precourt Institute of Energy

Stanford UniversitySIMES, SLAC National Accelerator Laboratory

chuehlab.stanford.edu

Pushing the Efficiency Limits of Energy Conversion and Storage

Through Rational Materials Design

ALS

ChuehLab.stanford.edu 2

D. Diliff

R. Laddish

C.‐Y. Yu

London

Toyko

Chicago

W.C. Chueh

Solar conversion

H2O

H2Capture

Storage

Delivery

Utilization

HydrogenStorage

Carbon‐free Source

HydrocarbonBatteries

e‐

Fuel cell

e‐

, CO2

H2O , CO2

Vision: Energy when & where it’s needed

3Courtesy S. Haile

ALS

ChuehLab.stanford.edu

Theme: Material optimization & discovery guided by fundamental insights

Model Systems High Performance Devices

200 µm1 µm

4

5 nm

ALS


ALSSSRL SNC

Sensitivity Spatial ResolutionTimescale

Theme: Material optimization & discovery guided by fundamental insights

ppb ps ‐ fs Å

As Electrochemistry Takes Place

W.C. Chueh

Solar conversion

H2O

H2Capture

Storage

Delivery

Utilization

HydrogenStorage



e‐

Fuel cell

e‐

, CO2

H2O , CO2


6

W.C. Chueh 7

Understanding battery charging & dischargingYiyang Li, Johanna Nelson

W.C. Chueh

Understanding battery charging & discharging

A123

DelithiatedLithiated

8

500 nm

W.C. Chueh

Can we see lithium move inside a battery?

705 710 715

Abso

rban

ce /

arb

Photon Energy / eV

LiFePO4

FePO4

500 nm

Lithium MapX‐ray Absorption

Photon Energy = 708 eV

J. Vila‐Comamala et al. Optics Express 22 (2011) 21333‐21344.

9

W.C. Chueh 10

Snapshots of battery charging

Chueh et al. Nano Lett. (2013). Accepted.

0 20 40 60 80 1000

20

40

60

80

100

169

nm

171

nm

151

nm

165

nm

106

nm

Frac

tion

/ %

Percentile in Particle Size

Li-rich Li-poor

133

nm

214

nm

248

nm

321

nm

191

nm

W.C. Chueh 11

Snapshots of battery charging

Chueh et al. Nano Lett. (2013). Accepted.

W.C. Chueh 12

What’s next?

Live imaging of battery charging in 3D

Improving rate capabilities of LiFePO4

Propagation Limited Initiation Limited

Polyester Film

Polymer Separator

Cathode

Current collector

Anode

X-rays

W.C. Chueh

Solar conversion

H2O

H2Capture

Storage

Delivery

Utilization

HydrogenStorage



e‐

Fuel cell

e‐

, CO2

H2O , CO2


13

ALS


1 gram of platinum for every kiloton of sand

93% of platinum is imported, 80% of world reserves in South Africa

Just enough platinum in the world to convert all American cars to fuel cells

Reduce the use of precious materials

U.S. Geological Survey, Fact Sheet 087‐02 14

ALS


Electrolyte

Air E

lectrode

Fuel Electrode

Fuel cells

GM Bloom Energy

ALS


Operating Temperature~ 400 to 600 °C

• Inexpensive system components (steel)

• Reliability

• Fast start‐up time

• Fast reaction rates

• No precious catalysts required

“Best of Both Worlds”

< 100 °C > 800 °C

Fast Oxygen Ion Conducting

Oxides

Not too cold, not too hot

Low Temp

High Temp

16

ALS


Ceria

YSZ

Ceria

YSZ

Ceria

YSZ

17

200 µm

1 µm

W. C. Chueh et al. Nature Mater. 11, 155‐161 (2012)

Eliminating metal altogether

Pt

ALS


Rxn. Coord

Energy

25 to 400 °C 109 increase in rate

1 eVSolid Electrolyte

e‐

Gas

O2‐

O2‐ O2‐ O2‐ O2‐e‐ e‐ e‐ e‐

SurfaceSub‐Surface

Bulk

?

Visualizing electrochemical reactions in fuel cells

18

Albert Feng, Mike Machala, David Mueller, Yezhou Shi

ALS


Bulk properties;Surface properties measured ex‐situ

Surface properties measured in‐situ

Electro‐catalytic

Activ

ity

19

Electro‐catalytic

Activ

ity

ALS


Ambient PressureX‐ray Spectroscopy

Surface X‐ray Scattering

X‐ray O

M

z

Environmental Transmission Electron Microscopy

20

Electrostatic Lenses

X‐ray Source

Sample~ 10 Torr

ALS


Going to a simpler, model system

500 µm

Bloom Energy

50 cm500 μm

21

ALS


How is charge transferred in a fuel cell electrode?

Ce CeO

CeO

CeO

H2 H2OH+

Ce Ce-O

Ce-O

CeO

H+

H2(g) + O2‐ H2O(g) + 2e‐

Solid Electrolyte

e‐

O2‐

O2‐ O2‐ O2‐ O2‐e‐ e‐ e‐ e‐

H2OH2

CeO2

Absence of surface oxygen

Surface electrons

W.C. Chueh

Solar conversion

H2O

H2Capture

Storage

Delivery

Utilization

HydrogenStorage



e‐

Fuel cell

e‐

, CO2

H2O , CO2


23

ALS


Re‐thinking the optimal temperature for water splitting

System cost

Reaction rates

Free energy for H2O dissociation

Temperature25°C > 1,000°C

Temperature

Dark Current

Traditional PEC

Ligh

t Abs

orbe

r

Water

sunlight

H2O(l) H2(g) + O2(g)

Is room temperature the best temperature?

Xiaofei Ye, Madhur Boloor

ALS


Ligh

t Abs

orbe

r

WaterSolid

Electrolyte “Shell”

Ligh

t Abs

orbe

r

A new class of elevated‐temperature photo‐electrochemical cell

• All solid, no liquid

• Reduced corrosion

• Potentially more efficient

ALS


H2O

H2

O2‐

O2

e‐

h+

hν

O2‐ ½O2(g) + 2e‐

H2O(g) + 2e‐ H2(g) + O2‐

26


Solid Electrolyte

“Shell”

Ligh

t Abs

orbe

r

ALS



10%

Efficiency

ALS



2.0 eV light absorber bandgap

Van

Mac

kele

nber

gh

ALS


• Finding materials with the right properties

• Stability at high temperatures

• Proof‐of‐concept device underway

What’s next?

ALS


Take home message

Fundamental insights enabled by new experimental techniques are challenging the current materials design and

optimization paradigms in energy conversion

These insights are leading to unexpected ways to improve performance and efficiency of batteries, fuel cells, and solar

fuels membranes

ALS


Johanna Nelson, Yezhou Shi (not shown)

Nick Melosh, ZX Shen, Mike Toney, Hirohito Ogasawara, Anders Nilsson

31

David Mueller

Yiyang Li

Xiaofei Ye

Michael Machala

Albert FengMe

Documents

Pushing the Efficiency Limits of and Storage - Energy...Pushing the Efficiency Limits of Energy Conversion and Storage Through Rational Materials Design. ALS ChuehLab.stanford.edu