nano-composite materials for energy storage devices: impact of...

www.nano-tech.gatech.edu

Gleb Yushin

[email protected]; www.nano-tech.gatech.edu

School of Materials Science & Engineering

Georgia Institute of Technology, Atlanta, GA 30332, USA

NAATBatt, January 18, 2013

Nano-Composite Materials for Energy Storage Devices:

Impact of the Electrode Architecture

Contributors and Collaborators: Benjamin Hertzberg, Kara Evanoff, Jim Benson, Sofiane

Boukhalfa, Hyea Kim, Jung Tae, Alexandre Magasinski, Igor Kovalenko, Patrick Dixon,

Bogdan Zhdyrko, Igor Luzinov, and others

mailto:[email protected]://www.nano-tech.gatech.edu/http://www.nano-tech.gatech.edu/http://www.nano-tech.gatech.edu/


Activities in Our Laboratory in the Past Years

Synthesis and

Characterization of

Porous Carbons

(primarily for EDLC

applications)

Synthesis, Modification

and Mechanical

Characterization of Metal

Nanostructures and

Nanostructured Films

Nano-Composite

Materials for Li-ion

Battery and

Supercapacitor

Applications

ACS Nano, 2011 Adv. Func. Mater., 2012

Adv. Func. Mater., 2011

Adv. Mater., 2011

Science, 2011

Electrochem. Comm., 2011

Adv. Ener. Mater., 2011

Adv. Ener. Mater., 2011

Small, 2011

Adv. Func. Mater., 2011 Environ. Science and Tech, 2011

Nature Mater., 2010

JACS, 2010

JACS, 2010

ACS Nano, 2010

J. Electrochem. Soc., 2010

Carbon, 2012

ACS Nano, 2011

Ener. Env. Science., 2012

Fundamental Studies of

Degradation Mechanisms

in Commercial Li-ion Cells

Carbon, 2012

will provide examples


Improving Stability and Power Capabilities

of High-Energy Electrodes

Ability to store energy of Li-ion batteries is largely governed by the ability of their electrode materials to host high content of ions

Many active materials exhibit outstanding ability for ion storage but suffer from large volume changes during insertion/extraction of ions (rapid electrode degradation) and/or low electrical and ionic conductivity (low power density)

Rational design of the architecture of high-capacity electrodes allows one to overcome these limitations while still achieving up to 90 % of the theoretical energy storage

Multi-functionality of battery (supercapacitor) electrodes permit for weight savings of the system

Many examples in this presentations deal with Si anodes, but they are broadly applicable to various materials


Vertically Aligned CNT - Based Electrodes

• Ultra-High electrical conductivity

• High thermal conductivity

• Thicker electrodes and thus smaller

contribution of inactive components

(separators, metal foils, etc.)

Traditional Electrodes

and Cell Architecture

• Low electrical conductivity

• Low thermal conductivity

• Heavy/bulky metal foils





Si- coated Vertically Aligned CNT Anodes

0 50 100 150 200 2500

1000

2000

3000

4000

De

allo

yin

g

Ca

pa

city /

mA

h g

-1 Si

Cycle Index

C/20 C/2C/5

Evanoff, K. et. al, Advanced Materials, 2011 Patent pending


Si-coated Vertically Aligned CNT Anodes

20 30 40 50 60 70 80 90 1000.1

1

10

100

1000

10000

Re

sis

tivity

/ O

hm

·cm

Temperature / oC

novel electrode based on Si and C coated VACNTs

conventional electrode composed of Si nanopowder

with carbon black additives and PVDF binder > 100 times lower electrical

resistance than that of

nanopowder electrode with

much higher density but

comparable thickness

Evanoff, K. et. al, Advanced Materials, 2011

20 30 40 50 60 70 80 90 1000.1

1

10

100

1000

10000

novel electrode based on Si and C coated VACNTs

conventional electrode composed of Si nanopowder

with carbon black additives and PVDF binder

Th

erm

al C

on

du

ctivity /

W·m

K-1

Temperature / oC

> 1000 times higher thermal

conductivity as compared to

nanopowder electrode with much

higher density but comparable

thickness

Excellent thermal properties of

the CNT-Cu interface


Multifunctional Nano-Composite Fabric

Traditional Electrodes

and Cell Architecture




• No mechanical strength

Uncoated portion of CNT fabric

also serves as a Current Collector Strong and flexible Mg- or

Si- coated CNT fabric as an

Anode

15-50 µm

Anode

15-50 µm

Cathode

Active coating (e.g., Si or Mg for anodes and LiV2O5 for cathodes)

Multifunctional Nano-Composite Fabric

• Ultra-High electrical conductivity

• High thermal conductivity

• No metal foil current collectors needed

• Enhanced safety (when solid electrolyte is

used)

• High mechanical strength / multi-

functionalilty

solid electrolyte


Si-C Nano-Composite Anode Fabric

20 40 60 80 100 120 1400

50

100

150

200

250

300

350

400

450

500

550

600

Regular Graphite-PVDF Anode on Cu foil

Li E

xtr

actio

n C

ap

acity (

mA

h/g

)

Cycle Index

Multifunctional Si-on-CNT Fabric Anode (54% Si)

(limited Li insertion to avoid Li insertion into CNT)

Regular Graphite Anode

Si-on-CNT Fabric Anode

1 mm

40 mm

Note:

Density of 90 um Graphite coating < 1.6 g/cc

(each side) ; Density of 18 um Cu = 9 g/cc

Evanoff, K. et. al, ACS Nano, 2012


Si-C Nano-Composite Anode Fabric

0.0 0.1 0.2 0.3 0.4 0.5 0.60

25

50

75

100

Si-CNT fabric before cycling

Si-CNT fabric after cycling

Str

ess / M

Pa

Strain / %

25

50

75

100

125

150

Str

uctu

ral ste

el A

36

Cast iron A

ST

M 4

0

Ti 99.5

%

Al allo

y 7

13

Al allo

y 5

14

Bra

ss

Cu 9

9.5

%

Cast iron A

ST

M 2

0

Specific

Str

ength

/ k

Nm

kg

-1

Al allo

y 4

43

Si-

CN

T

fab

ric

Evanoff, K. et. al, ACS Nano, 2012

0 5 10 15 20 25 30 350

25

50

75

100

125

150

175

Ar annealing at 500 oC

CNT fabric after Str

ess / M

Pa

Strain / %

synthesized CNT fabric


Metal Oxide / Carbon

Nanocomposites for Supercapacitors

(a)

(b)

(c)

(d)

1 µm

1 µm

1 µm

1 µm

not coated CNTs

100 ALD cycles

300 ALD cycles

500 ALD cycles

0 100 200 300 400 50060

80

100

120

140

160

180

Ave

rag

e t

ub

e d

iam

ete

r (n

m)

Number of ALD cycles

In an ideal case ALD is a surface-limited process, the

average coating thickness or the average tube diameter

should increase proportionally to the number of the ALD

cycles

An ImageJ software analysis of multiple SEM micrographs

reveals linear increase in the average tube diameter with the

number of ALD cycles, suggesting that the time allocated for

the diffusion of the precursor gases into the porous structure

in each cycle was sufficient for the reaction to be surface

kinetics-controlled

Coating thickness

increases at

0.1nm/cycle


5 10 15 200

400

800

1200

1600

Sp

ecific

Ca

pa

cita

nce

(F

g(V

Ox)-

1)

Current Density (A g-1)

100 ALD cycles

300 ALD cycles

500 ALD cycles

5 10 15 20

0

100

200

300

400

500

600

Sp

ecific

Ca

pa

cita

nce

(F

g-1)

Current Density (A g-1)

100 ALD cycles

300 ALD cycles

500 ALD cycles

not coated CNT electrode

0 4 8 12 16-0.6

-0.3

0.0

0.3

0.6

Vo

lta

ge

(V

)

Time (s)

20 A g-1 scan rate

100 ALD cycles

300 ALD cycles

500 ALD cycles

IR

Vanadium oxide capacitance >

1000 F/g at very high current

density of 20 A/g

Very small IR drop at 20 A/g

S. Baukhalfa, K. Evanoff and G. Yushin, Energy & Env. Science, 2012

Metal Oxide / Carbon Nanocomposites

for Supercapacitors


Catalyst-Free Al Nanowire Growth by CVD

• Trimethylamine alane (TMAA) as an organometallic CVD precursor

• Catalyst-free

0 1 2 3 4 5

Al

Inte

nsi

ty (

a.u

.)

Energy (keV)

O

(a)

Cu foil Forest of Al nanowires

2 cm

Gas flow

(b)

100 nm

(c) Al nanowires on Cu

Limitation of the CNT:

- low DC conductivity (compared to Al and Cu)

- low concentration of dangling bonds

Metal nanowires:

- typically grown electrochemically using AAO template

- CVD growth (as CNTs) might offer more scalable process

J. Benson et al., ACS Nano, 2011


ALD-coated Al Nanowires

Battery-like AND pseudocapacitor-like behavior

Gravimetric capacitance of up to 887 F/g is 4-10 time higher than C

Volumetric capacitance of 1390-1950 F/cc is10-40 times higher than

that of C in the same electrolyte

(a) Al nanowire core

Cu foil

VOx coating

1.0 1.5 2.0 2.5 3.0

-3000

-2000

-1000

0

1000

2000

3000

porous carbon

used in commercial

supercapacitors

Ca

pa

cita

nce

(F

g-1)

Potential vs. Li/Li+ (V)

VOx coating on

Al nanowires

(e)

0.1 1 10 1000

100

200

300

400

500

600

700

800

900

porous carbon

used in commercial

supercapacitors

Capa

citance

(F

g-1)

Scan Rate (mV s-1)

50 nm VOx coating

VOx - coated

Al nanowires

300 nm

(b)

(f)

(c)

200 nm amorphous

VOx coating

Al nanowire

core

1 2 3 4 5 6

Al

O

Energy (keV)

Inte

nsity (

a.u

.)

V

(d)

J. Benson et al., ACS Nano, 2011


Drop-in Replacement: Si-C Nanocomposite Powder

produced using Hierarchical Bottom-up Assembling

Si nanoparticles’

assembly on the surface

of annealed CB

Assembly of Si-

coated CB particles

into rigid spherical

granules

Annealed carbon

black (CB)

100 nm

Si

Magasinski, A. et. al, Nature Materials, 2010

• Uniformity of the deposited Si nanoparticles

• No volume changes during Li insertion/extraction

• Compatibility with existing manufacturing

technologies (drop-in replacement)

• High electrical & thermal conductivity

Patent pending


Environmentally-friendly process: (a) growing algae captures CO2 and

produced O2; (b) alginate (as a Na-alginate) is produced from brown algae

by boiling it in a soda solution (no need for extensive chemical treatment; in

contrast, CMC synthesis involves the alkali-catalyzed reaction of cellulose

with chloroacetic acid to introduce carboxy groups); (c) solvent – water (in

contrast, PVDF requires NMP)

Alginate is extracted from

brown algae, which is: (a) the

fastest growing plant on the

planet, (b) does not need

agricultural land

Studies of Inactive Components: Electrolytes, Binders, etc.

I. Kovalenko et al., Science, 2011


Recent Activities in Our Laboratory

Cathodes for Mg-ion

Batteries (potentially

higher energy and

lower cost than Li-ion)

Anodes for Na-ion

Batteries (potentially

higher power and lower

cost than Li-ion)

Nanostructured & smooth

electro-deposition of metal

coatings on various

substrates (foils, carbon

fibers, CNTs) :

Mg and Al

• In contrast to Li, Mg

foil can be used as an

anode in Mg-ion cells

(no dendrites)

• Greatest challenge -

high-rate / high

capacity cathodes

(large +2 ion charge)

• Nearly all cathode

structures for Li-ion

batteries can be

effectively used for

Na-ion batteries

• Greatest challenge –

high-rate / high-

capacity anodes

(graphite does not

work)

• Uniform electro-deposition

of nano-grained metal

coatings is a challenge

• Applications range from

structure support to energy

storage (even as counter

anodes in half cells)


Recent Activities in Our Laboratory

High-Energy

Conversion-type

Cathodes for Li-ion

batteries

• Matching high-

capacity anodes with

high-capacity cathodes

may allow 2-3 times

improvements in the

volumetric energy

density of Li-ion cells

Room Temperature Solid

Inorganic Electrolytes for

Li-ion batteries

• Higher voltage

• Higher safety

• Potentially longer cycle life

• Broader operational T

• Potentially higher charge

rate

Li-S & Na-S Cells

• Low-cost, high-energy

density systems


Thank you!

GT patents have been licensed to Sila Nanotechnologies, Inc.,

G. Yushin & Georgia Tech are stock holders in Sila Nanotechnologies, Inc.

Disclosure

Funding

nano-composite materials for energy storage devices: impact of...

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