affect the operating potential of an electrode Megan Butala June 2 2014 Hayner Zhao amp Kung Annu Rev Chem Biomolec Eng 3 44571 2012 A wide range of electrode potentials ID: 339225
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Slide1
How transition metal, anion, and structure
affect the operating potential of an electrode
Megan
Butala
June 2, 2014Slide2
Hayner
, Zhao & Kung.
Annu .Rev. Chem. Biomolec. Eng. 3, 445–71 (2012).
A wide range of electrode potentials
can be achievedSlide3
Power and energy are common metrics
for comparing energy storage technologies
Hayner, Zhao & Kung. Annu .Rev. Chem. Biomolec
. Eng.
3,
445–71 (2012).Slide4
What physical phenomena
are described by these metrics?
Specific energy = capacity × VocSpecific power = Specific energy × time to chargeSlide5
What physical phenomena
are described by these metrics?
Specific energy = capacity × VocSpecific power = Specific energy × time to charge
charge stored per mass active material
xLi
+
+
xe
-
+ Li
1-x
CoO
2
LiCoO
2
Ex:Slide6
What physical phenomena
are described by these metrics?
Specific energy = capacity × VocSpecific power = Specific energy × time to charge
charge stored per mass active material
V
oc
= (
μ
A
–
μ
C
)/
e
V
oc
= EMF
C
- EMF
A
xLi
+
+
xe
-
+ Li1-xCoO
2 LiCoO2
Ex:Slide7
How a battery works
V and chemical potential
Batteries by DOSSlide8
How a battery works
V and chemical potential
Batteries by DOSSlide9
Anode
Cathode
Li
+
ions and electrons are shuttled between electrodes to store and deliver energySlide10
Anode
Cathode
e
-
Li
+
Li
+
Applying a load to the cell drives Li
+
and electrons to the cathode during dischargeSlide11
Anode
Cathode
e
-
Li
+
Li
+
V
Applying a voltage to the cell drives Li
+
ions and electrons to the anode during chargeSlide12
How a battery works
V and chemical potential
Batteries by DOSSlide13
We can consider the energies of
the 3 major battery components
Goodenough & Kim. Chem. Mater. 22, 587-603 (2010)
.
e
V
oc
= μA - μC
V
oc
= EMF
C
- EMF
ASlide14
We can consider the energies of
the 3 major battery components
Goodenough & Kim. Chem. Mater. 22,
587-603
(
2010)
.
eVoc = μ
A
-
μ
C
V
oc
= EMF
C
- EMF
ASlide15
An electrode’s EMF can be understood
by the nature of its DOS
Goodenough
& Kim.
Chem. Mater.
22,
587-603 (2010).Slide16
An electrode’s EMF can be understood
by the nature of its DOS
Goodenough
& Kim.
Chem. Mater.
22,
587-603 (2010).
Lower orbital energy = higher potentialSlide17
How a battery works
V and chemical potential
Batteries by DOSSlide18
The potential of an electrode depends on chemistry and structure
M
aXb
M
=
transition metal
X = anion (O, S, F, N)
X
p-band
M
d
n+1
/
d
n
M
d
n
/d
n-1
ESlide19
Transition metal energy stabilization shows trends from L to R based on ionization energy
Goodenough
& Kim.
Chem. Mater.
22,
587-603
(2010).Slide20
Transition metal energy stabilization shows trends from L to R based on ionization energy
Goodenough
& Kim.
Chem. Mater.
22,
587-603
(2010).
Ti
CoSlide21
Transition metal energy stabilization shows trends from L to R based on ionization energy
Goodenough
& Kim.
Chem. Mater.
22,
587-603
(2010).
Ti
CoSlide22
Adapted from
Goodenough
& Kim. Chem. Mater. 22, 587-603 (2010).
S
p-band
O
p-band
F
p-band
E
The relative stabilization and bandwidth of the anion (
X
) p-band vary with electronegativity
EN ↑Slide23
The relative stabilization and bandwidth of the anion (
X
) p-band vary with electronegativityAdapted from Goodenough & Kim. Chem. Mater. 22, 587-603 (
2010)
.
S
p-band
O
p-band
F
p-band
E
BW
EN ↑Slide24
M
a
Xb
X
p-band
M
d
n+1
/
d
n
M
d
n
/d
n-1
E
U
Δ
Mott-Hubbard vs. charge transfer dominated character will alter potential
Zaanen
,
Sawatzky
& Allen.
Phys. Rev.
Lett
.
55
, 418-421 (1985)
Cox. “The Electronic Structure and Chemistry of Solids”.
Oxford Science Publications
(2005)Slide25
M
a
Xb
X
p-band
M
d
n+1
/
d
n
M
d
n
/d
n-1
E
U
Δ
Directly related to
Madelung
potential and EN of anion
X
Mott-Hubbard vs. charge transfer dominated character will alter potential
Zaanen
,
Sawatzky
& Allen.
Phys. Rev.
Lett
.
55
, 418-421 (1985)
Cox. “The Electronic Structure and Chemistry of Solids”.
Oxford Science Publications
(2005)
Increases across the row of TMs from L to RSlide26
M
a
Xb
X
p-band
M
d
n+1
/
d
n
M
d
n
/d
n-1
E
U
Δ
Mott-Hubbard vs. charge transfer character
will alter electrode potential
X
p-band
M
d
n+1
/
d
n
M
d
n
/d
n-1
E
U
Δ
early TM compounds
M =
Ti, V, . . .
late TM compounds
M =
Co, Ni, Cu, . . .Slide27
M
a
Xb
X
p-band
M
d
n+1
/
d
n
M
d
n
/d
n-1
U
EMF
Mott-Hubbard vs. charge transfer character
will alter electrode potential
X
p-band
M
d
n+1
/
d
n
M
d
n
/d
n-1
Δ
early TM compounds
M =
Ti, V, . . .
late TM compounds
M =
Co, Ni, Cu, . . .
Li
+
/Li
0
Li
+
/Li
0
EMFSlide28
For early TMs, we can consider the potential to be defined by the d-band redox couples
Adapted from
Goodenough & Kim. Chem. Mater. 22, 587-603 (2010)
.
Li
0
Ti
S
2
Li
+
/Li
0
S
p-band
Ti
d
4+
/d
3+
Ti
d
3+
/d
2+
EMFSlide29
For early TMs, we can consider the potential to be defined by the d-band redox couples
Adapted from
Goodenough & Kim. Chem. Mater. 22, 587-603 (2010)
.
Li
0
Ti
S
2
S
p-band
Li
0.5
Ti
S
2
EMF
EMF
We approximate the
d-band to be sufficiently narrow that a redox couple will have a singular energy
Li
+
/Li
0
Ti
d
4+
/d
3+
Ti
d
3+
/d
2+Slide30
For early TMs, we can consider the potential to be defined by the d-band redox couples
Adapted from
Goodenough & Kim. Chem. Mater. 22, 587-603 (2010)
.
Li
0
Ti
S
2
S
p-band
Li
Ti
S
2
Li
Ti
S
2
EMF
Li
+
/Li
0
EMF
EMF
Ti
d
4+
/d
3+
Ti
d
3+
/d
2+Slide31
Structure also affects potential: LiMn
2
O4 has octahedral and tetrahedral Li sitesThackeray, Jahnson, De Picciotto, Bruce & Goodenough
.
Mater. Res. Bull.
19,
435 (1984).
Li
x
Mn
2
O
4
Li
+
/Li
0
O
p-band
Mn
(
tet
-Li)
d
4+
/d
3+
Mn
(
oct
-Li)
d
4+
/d
3+
tetrahedral
octahedralSlide32
Structure also affects potential: LiMn
2
O4 has octahedral and tetrahedral Li sitesThackeray, Jahnson, De Picciotto, Bruce & Goodenough
.
Mater. Res. Bull.
19,
435 (1984).
Li
x
Mn
2
O
4
Li
+
/Li
0
O
p-band
Mn
(
tet
-Li)
d
4+
/d
3+
Mn
(
oct
-Li)
d
4+
/d
3+
tetrahedral
octahedral
EMFSlide33
Structure also affects potential: LiMn
2
O4 has octahedral and tetrahedral Li sitesThackeray, Jahnson, De Picciotto, Bruce & Goodenough
.
Mater. Res. Bull.
19,
435 (1984).
Li
x
Mn
2
O
4
O
p-band
Mn
(
tet
-Li)
d
4+
/d
3+
Mn
(
oct
-Li)
d
4+
/d3+
tetrahedral
octahedral
EMF
Li
+
/Li
0Slide34
We can think about electrode EMF by DOS
M
aXb
M
=
transition metal
X = anion (O, S, F, N)
X
p-band
M
d
n+1
/
d
n
M
d
n
/d
n-1
E
Position and BW of
M
d-bands
ionization energy EN of anion
coordination of MPosition and BW of anion p-band EN of anion
Madelung potentialCharge transfer vs. Mott-Hubbard Nature of M and XSlide35
We can tailor electrode potential
to suit a specific application
Specific energy = capacity × VocSpecific power = Specific energy × time to charge . . . but that is one small piece of battery performanceSlide36
We can tailor electrode potential
to suit a specific application
Specific energy = capacity × VocSpecific power = Specific energy × time to charge . . . but that is one small piece of battery performance
And these other factors depend heavily on kinetics and structure.Slide37
We can think about
electrode EMF by
DOSMaX
b
M
=
transition metalX = anion (O, S, F, N)
X
p-band
M
d
n+1
/
d
n
M
d
n
/d
n-1
E
Position and BW of
M
d-bands
ionization energy EN of anion coordination of MPosition and BW of anion p-band
EN of anion Madelung potentialCharge transfer vs. Mott-Hubbard Nature of M
and XSlide38
Hayner
, Zhao & Kung.
Annu .Rev. Chem. Biomolec. Eng. 3, 445–71 (2012).
A wide range of potentials can be achievedSlide39
Power and energy are common metrics
for comparing energy storage technologies
Hayner, Zhao & Kung. Annu .Rev. Chem. Biomolec
. Eng.
3,
445–71 (2012).Slide40
cycling
Commercial electrodes typically function through Li intercalation
xLi
+
+
xe
-
+ Li1-xCoO2
LiCoO
2
Ex:Slide41
Madelung
potential
Correction factor to account for ionic interactions – electrostatic potential of oppositely charged ionsVm = Am(z*e)/(4*pi*Epsilon0*r)