New Perspectives in Energy Storage Materials

New Perspectives in
Energy Storage
Materials
Confocal Micro-Raman Microscopy
Jagjit Nanda
Materials Science and Technology Division
nandaj@ornl.gov

t
10 3 s
1 s
10 -3 s 10 -6 s
10 -9 s
The Scale of Things
Primary
Particles
Secondary
Particles
Cell
Electrode
10 -9 m 10 -6 m 10 -3 m 1 m
• Complex electrode assembly
• Multiple transport regime
• Spatio-temporal variation
Courtesy : Sreekanth Pannala
Battery Pack
x

Working of a Li-ion full cell

Connecting Fundamental Material Properties
to Macroscopic Parameters
• Single particle “State of Charge” (SOC).
“Enabler for full capacity utilization”
• Observation of “Lithium Gradient” in an inhomogeneous
medium.
4 Managed by UT-Battelle
for the U.S. Department of Energy
“ Transport in a complex electrode assembly”

5 Managed by UT-Battelle
for the U.S. Department of Energy
Confocal Raman-AFM Setup
Support from Energy Storage, OVT, EERE DOE
Spatial Resolution ~ 300 nm
Peizo driven mapping stage
Multiple excitation wavelength
Raman Imaging plus topography

60 µm 5 µm 700 nm
6 Managed by UT-Battelle
for the U.S. Department of Energy
High Energy and Power Li-ion Electrodes
Electrode Secondary particle Primary particle
Edge
25 µm
LiNi 0.80Co 0.15Al 0.05O 2 (NCA)
LiNi 0.33Co 0.33Mn 0.33O 2 (NCM)
xLi 2MnO 3 (1-x)LiMO 2 ( Excess Lithia compounds)

Counts
1200
1100
1000
900
800
700
600
500
400
Origin of spectroscopic “SOC”
475 cm -1
E g
550 cm -1
300 400 500 600 700 800
Raman shift / cm-1
A 1g
Charged NCA cathode (3.77V)
a - NaFeO 2 structure
oxygen
metal
• A1g – oxygen atoms vibrate in opposite directions parallel to c-axis
• Eg – oxygen atoms vibrate alternately in opposite directions parallel to Li and
transition metal planes.
• SOC proportional to A 1
A 1
/
475 cm 550cm
a
c
LiMO 2
M = Ni, Co

Counts
1200
1100
1000
900
800
700
600
500
400
Micro-Raman Technique
Positive Electrode Negative Electrode
Raman spectrum of charged
Raman Spectrum of Graphite
(3.77 V) NCA Cathode
Anode
~470 cm-1 ~550 cm-1
300 400 500 600 700 800
Raman shift / cm-1
A 470/A 550 ~ to SOC
Counts
1300
1200
1100
1000
900
800
700
600
500
400
300
200
D1 -Band
G -Band
1200 1300 1400 1500 1600 1700
Raman shift / cm-1
A D1/A G ~ Disorder
Spectra can be obtained as a function of position on the surface and
edge of the electrode material.
8

9 Managed by UT-Battelle
for the U.S. Department of Energy
Carbon Coverage : Continued
Intensity
3000
2500
2000
1500
1000
500
X = -5, Y=1
X = 5, Y = 1
Fresh Sample (uncycled)
0
200 400 600 800 1000 1200 1400 1600 1800
Raman Shift (cm -1 )
Similar carbon coverage different particle “SOC”
Uncharged
NCA

Intensity Map
Carbon
J. Nanda et al. 2010
10 Managed by UT-Battelle
for the U.S. Department of Energy
Raman Mapping : What it can do ?
Optical Micrograph Intensity Map (NCA)
Micron
State of Charge : (A 475 / A 550) × (I 475 / I 550)
SOC Map
NCA

Counts
Counts
Mapping Lithium Deficiency Regions : Li 1-xNi 0.80Co 0.20Al 0.05
7000
6000
5000
4000
3000
2000
1000
900
800
700
600
500
400
300
Spectroscopic Signature
300 400 500 600 700 800
11 Managed by UT-Battelle
for the U.S. Department of Energy
A 470/A 550 ~ 0.4
Raman shift / cm-1
A 470/A 550 ~ 1.2
300 400 500 600 700 800
Raman shift / cm-1
Edge
Mapping Pattern Surface
Microns

Y (µm)
X (µm)
12 Managed by UT-Battelle
for the U.S. Department of Energy
Severely degraded Sample
SOC Map
Current Current collector collector side side
Count
180
160
140
120
100
J. Nanda et al. Under reveiw 2010
Extreme charged regions
80
60
40
20
degraded band cathode cross-section
0
0 1 2 3 4 5
area x intensity

Counts
Counts
1300
1200
1100
1000
900
800
700
600
500
400
300
1700
1600
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
A D1/A G ~ 0.1
1200 1300 1400 1500 1600 1700
13 Managed by UT-Battelle
for the U.S. Department of Energy
Spatial anode maps of A D1/A G -greater
value, more graphite disorder (damage)
Raman shift / cm-1
1200 1300 1400 1500 1600 1700
Raman shift / cm-1
A D1/A G ~ 1.8

In situ Li-transport in Li-ion full cell
Al
e -
Li +
Separator
Cathode Anode
14 Managed by UT-Battelle
for the U.S. Department of Energy
30µm
Cu
current
collector

Counts
Counts
Counts
Counts
Counts
2500
2000
1500
2500
2000
1500
3000
2500
2000
1500
2500
2400
2300
2200
2100
2000
1900
1800
1700
1600
1500
1400
1300
1200
1100
2400
2300
2200
2100
2000
1900
1800
1700
1600
1500
1400
1300
Single Particle Charge-discharge of an in situ edge cell
300 400 500 600 700 800
1 – 0.98
Raman shift / cm-1
300 400 500 600 700 800
2 – Raman shift 1.00
/ cm-1
300 400 500 600 700 800
3 – Raman 1.12
shift / cm-1
300 400 500 600 700 800
4 – Raman 1.05
shift / cm-1
300 400 500 600 700 800
Raman shift / cm-1
300 5 – 1.12
15 Managed by UT-Battelle
for the U.S. Department of Energy
5
7
Counts
2200
2100
2000
1900
1800
1700
1600
1500
1400
1300
1200
3
1 2
Cell voltage 3.7 V
Avg. Area 474/Area 551 = 1.02 ± 0.10
400 500 600 700 800
Raman shift / cm-1 7 – 1.11 300
Counts
2500
2400
2300
2200
2100
2000
1900
1800
1700
1600
1500
1400
1300
1200
10
9
6
8
4
8 – 1.12 300
400 500 600 700 800
Raman shift / cm-1
Pos. → 472.1 ± 0.76 cm -1
Width → 56.4 ± 2.2 cm -1
Counts
Counts
2400
2300
2200
2100
2000
1900
1800
1700
1600
1500
1400
1300
1200
1100
2400
2300
2200
2100
2000
1900
1800
1700
1600
1500
1400
1300
1200
1100
electrode
300 400 500 600 700 800
10 – 0.99
Raman shift / cm-1
9 – 0.98
400 500 600 700 800
Raman shift / cm-1
x
Pos. → 547.2 ± 0.91 cm -1
Width → 56.9 ± 2.0 cm -1

Intensity
4000
3000
2000
1000
3.93 V
3.77 V
3.6 V
3.52 V
3.47 V
3.1 V
472 (60.8)
Observing “single particle” state of charge
Cathode Particle
475.5 (55.42)
475.9 (51.3)
476.3 (51)
Cathode Particle 2
Near Separator
473.9 (52.9) 550.3 (56.1) 0.84
200 300 400 500 600 700 800
Raman Shift (cm -1 )
547.5 (61.8)
471.33 (54.42) 448.3.5 (61.6) 0.71
550.5 (48.7)
553.1 (50)
553 (50)
0.87
0.94
1.03
1.43
Separator
Intensity
20 µm
7000
6000
5000
4000
3000
2000
3.93 V
3.73 V
3.65 V
3.52V
3.34 V
3.0 V
Anode Particle
Galvanostatic at 1C rate
10 µm
Anode Particle Near Separator
1300 1400 1500 1600 1700
Raman Shift (cm -1 )
1581.0 cm -1
1589.0 cm -1
1589.77 cm -1
Graphite
Li xC 6
~ LiC 6

Intensity
4000
3000 3.41 V
2000
3.68 V
1000
3.1 V
3.1 V
3.51 V
3.84 V
4.17 V
4.00 V
3.87 V
474.8 (54.1)
474.8 (51.0)
Dynamical Potentiostatic Condition
In-situ Cell
Cat Spot 3
May 21
0
300 400 500 600 700
Raman Shift (cm -1 )
549 (50.64)
550.1 (53.8)
-145 Ah
-145 Ah
-200 Ah
-200 Ah
-200 Ah
+444 Ah
1.01
+200 Ah
0.89
SOC α
A
Intensity
2500
2000
1500
1000
500
J. Nanda et. al. Manuscript (2010)
4.15V
4.05V
3.75 V
3.5 V
In-Situ Cell
Cat Spot 3
May 21
0
300 400 500 600 700
A
1
/ 1
475 cm 550cm
Raman Shift (cm -1 )
+ 373 A
+ 310 A
+ 386 A
+ 200 A

Intensity
Intensity
8000
7000
6000
5000
4000
3000
2000
1000
13000
12000
11000
10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
Fully Discharged
1b: 700 - 639 A
1c: 471 - 439 A
1 d: 353 - 335 A
Particle 1
1e: PS @ 3.85V (599 - 462 A)
1f: PS @ 3.95V (487 - 404 A)
1g: PS @ 3.95V (228 - 222 A)
1 h: PS @ 3.95V (142 - 137 A)
1I: PS @ 4.05 V (107 - 102 A)
1J PS @ 4.15 V (134 - 111 A)
1 k PS @ 4.2 V( 55 - 54 A)
Dynamical Potentiostatic Condition
Data recorded during PS @ 3.75 V
1300 1400 1500 1600 1700
Raman Shift (cm -1 )
1589.45
1589
1586.8 (13.7)
1582 (17)
1589.5
( 30 averages)
J. Nanda et al. (unpublished)
Hardwick et al. Solid State Ionics 177 (2006)

Intensity Intensity
µm
600
500
400
300
200
100
Si Si
High Capacity Si-C Composite Anode
D D 1 I
Raman Shift (cm-1 Raman Shift (cm ) -1 )
G
G
0
400 600 800 1000 1200 1400 1600
µm
D D II 2
Raman Raman Raman Intensity Intensity Intensity (arbitary (arbitary (arbitary units) units) units)
20000
16000
12000
1st 1 discharge cycle
st 1 discharge cycle
st discharge cycle
0.85 V
0.45 V
0.35 V
0.2 V
0.08 V
0.05 V
1st 1 charge cycle
st 1 charge cycle
st charge cycle
µm In-situ observation of lithiation of silicon-rich region in Si-C composite
Ratio of Si area to G-Band area
(a)
Nanda et al. Electrochem. Comm. (2009)
10 µm
(b)
10 µm
475 500 525 550 575
Wave Number (cm -1 475 500 525 550 575
Wave Number (cm )
-1 475 500 525 550 575
Wave Number (cm )
-1 )
1V
0.6V
0.4 V
500 550
19

Conclusions
• Relative measure of spatial SOC distribution of cathode
particle aggregates.
• Raman Intensity versus State of Charge : Skin Depth
Effect.
• Micron level mapping of electrodes: Observation of Ligradient.
• Kinetics of lithiation-delithiation at the primarysecondary
particle interface
20 Managed by UT-Battelle
for the U.S. Department of Energy