Batteries And Electrochemical Capacitors

impending introduction of large fleets of
gasoline-electric hybrid vehicles, which
will help alleviate, at least momentarily,
the worldwide impact on the economy
and the environment induced by the
inexorable depletion of fossil fuels and
the release of greenhouse gases into
the atmosphere. Driven primarily by
a fast-growing and highly competitive
market and the support of governments,
Batteries and
scientists and engineers in industry,
academia, and national laboratories have
engaged in a frenzied search of means
for maximizing battery performance in
Electrochemical
terms of power and capacity, i.e., the
actual charge the device can store, while
minimizing weight and volume and
Capacitors
mitigating safety risks.
General Considerations
by Daniel A. Scherson and Attila Palencsár
Batteries consist of single (although
the term defines a collection), or mul-
tiple galvanic cells, connected in series
The invention of the battery can be attributed to Alessandro
to generate higher voltages. For example,
Volta (1745-1827) of Como, Italy, who in 1800 described an
in a car battery, six individual 2.0 V lead-
acid cells provide 12 V. Each such cell
assembly consisting of plates of two different metals, such as
consists of two electrodes: the anode, or
Zn and Cu, placed alternately in a stack-like fashion separated
source of electrons, and the cathode, or
by paper soaked in an aqueous solution, such as brine or
sink of electrons, labeled, respectively, as
vinegar. As discovered by Volta, this contraption was capable of
negative and positive in consumer batter-
ies. Whereas the voltage of a cell (E ) is
producing an electrical shock when its ends were touched. In
cell
prescribed by the nature of the chemical
a broad sense, batteries can be deﬁ ned as devices that convert
reactions at the two electrodes, the power
chemical into electrical energy using electrodes, immersed in
it can deliver, defined as the product of
the voltage (E) and the current (I), are
media (liquids, gels, and even solids) that support the transport
governed by much more subtle factors.
of ions, or electrolyte. This mode of operation is fundamentally
Some batteries can be used only once,
different from that associated with conventional solid-state
so-called non-rechargeable or primary,
and others multiple times, rechargeable
capacitors, invented about half a century earlier in Leyden,
or secondary. The most common primary
The Netherlands, in which charge is physically stored in
battery, i.e., Zn|MnO , is depicted in Fig.
2
nonreactive electrodes separated by a dielectric, or insulating
1a. For this system, the anode is a collec-
tion of Zn metal particles dispersed in a
material. However, the latter shares important commonalities
strongly alkaline aqueous solution mixed
with yet another class of devices developed much later known
with a polymer, and the cathode is a hol-
as electrochemical capacitors, which, as described later in
low molded cylinder made out of MnO .
2
Direct physical (electronic) contact
this article, rely on charge separation at electrode|electrolyte
between the two electrodes (and, thus,
interfaces to store energy.
(continued on next page)
Automotive, communications,
and a host of consumer market
applications, introduced in the first
quarter of the twentieth century, made
batteries a household term. However,
the technological explosion brought
about by the advent of the transistor
and the concomitant miniaturization
of electronic circuitry (as eloquently
evidenced by the seemingly ever-evolving
multifunctional cell phones, portable
digital assistants, laptop computers,
digital cameras, games, and, more
recently, portable media devices, such as
the iPod), may be regarded as perhaps
the major factor responsible for batteries
becoming among the most ubiquitous
devices ever invented. Further major
market expansions are expected from the
FIG. 1. (a) Schematic diagram of commercial primary (non-rechargeable) Zn|MnO and (b) secondary
2
(rechargable) Ni|MH batteries. Adapted with permission from the manufacturers.
The Electrochemical Society Interface • Spring 2006
17

Batteries and
anode, denoted as MH, consists of an
Electrochemical Capacitors
alloy incorporating an array of mainly
(continued from previous page)
rare earth elements (or mischmetal).
During charging, the metal sites in
Ni(OH) undergo oxidation to yield
2
NiOOH, whereas the anode reduces
water to elemental hydrogen, which
combines with the metal to form a
hydride, a virtual hydrogen storage. The
construction of this battery differs from
that of Zn|MnO in that the electrodes
2
are sandwiched with the separator in
between and wound to form a cylinder,
resembling a jellyroll.
Selection of a battery for a specific
device is often made based primarily
on its performance characteristics. One
such figure of merit is obtained by
applying a constant current (I), while
monitoring E as a function of time.
cell
Shown in Fig. 2 is a plot of E vs. time
cell
FIG. 2. Cell voltage (E ) vs. time (in hours) for the discharge of a AA
cell
for various I for an AA Ni
Ni
|MH battery.
|MH battery at various constant currents as indicated. Adapted with
As indicated therein, for I = 250 mA (see
permission from the manufacturer.
purple curve, top), E decreases slowly
cell

during the first 2 h to reach a fairly
constant plateau. After about 6 h, E
cell
once again drops first slowly and then
Li-ion
150
suddenly at about 10 h signaling the end
of the battery useful life. Based on the
observed lifetime, the charge or capacity
the battery can deliver under these
100
conditions, is 10 h × 3600 s/h × 0.25 A =
Ni|MH

9000 coulombs (denoted C), or in battery
technology units, 2500 mAh (250 mA
× 10 h). If I is increased, for example,
50
Ni|Cd
to meet the demands of a more power
hungry device, the observed useful life
of the battery is obviously shorter, as
illustrated by the blue curve, Fig. 2 top,
S
p
e
c
i
f
i
c

e
n
e
r
g
y
,

W
h
/
k
g
0
for I = 500 mA. Nevertheless, based on
0.1
1
10
100
the same calculation presented above,
Specific power, W/kg
the useful capacity of the battery remains
virtually unchanged. Manufacturers
FIG. 3. Speciﬁc energy vs. speciﬁc power or Ragone plots, for three common
often quote discharge rates in units of
rechargeable batteries. Ref: Handbook of batteries, D. Linden, T. B. Reddy,
C (which, although it bears the same
Eds., McGraw-Hill, New York (2002), 3rd Edition.
symbol, is not to be confused with that
for coulombs) where C/1 corresponds to
a short) is prevented by placing a non-
The voltage of an off-the-shelf
the current at which the useful capacity
woven fabric or separator between them,
Zn|MnO cell, as measured with a high
2
of the battery is consumed in 1 h. For the
which also serves to hold sufficient
impedance voltmeter (which draws
results shown in Fig. 2 top, the capacity
electrolyte to establish ionic continuity
only a miniscule current) is E ~ 1.5 V.
cell
of the battery for I = 250 and 500 mA
within the battery. The intrinsic elec-
This value corresponds to the sum of
was exhausted in 10 (purple curve) and
tronic conductivity of MnO is too low to
the individual half-cell potentials of
2
5 h (blue curve), which corresponds to
sustain high currents; hence, a conduc-
the two electrodes, as predicted by
discharge rates of 0.1 C (or C/10) and 0.2
tivity enhancer, most commonly a high
the corresponding Nernst equations,
C (or C/5), respectively.
surface area graphitic carbon, must be
although the precise nature of the
incorporated into the cathode to improve
electrochemical reactions involved have
As the C rate is increased beyond
its performance and a polymeric binder
been the subject of much heated debate.
a certain limit, however, the capacity
for mechanical stability. Electrons are
During operation, E is always smaller
of the battery can no longer be fully
cell
generated at the anode, via the oxidation
than its open-circuit value (no load) and
utilized. This is clearly illustrated for
of metallic Zn to yield a Zn2+ species, a
a function of both the demands imposed
the AA Ni|MH battery discharged at 2
two-electron transfer process, and are
by the device it powers and the depth to
C (see magenta curve, Fig. 2 bottom),
collected by a metal pin current collector
which the battery has been discharged.
for which the lifetime falls short of the
inserted in the Zn paste as shown in Fig.
0.5 h predicted based on the results
An example of a popular rechargeable
1. After flowing through the load, such
obtained at the lower C rates. A fraction
system is the Ni metal hydride (Ni|MH)
as a light bulb, the electrons are delivered
of valuable electrode material remained
battery, E ~ 1.2 V, shown schematically
through a steel casing current collector,
cell
unused, an effect found for all battery
in Fig. 1b. Its active cathode material is
to the MnO cathode, where the Mn4+
systems for sufficiently high C rates. It
2
nickel hydroxide, Ni(OH) , which has
ions are reduced to a lower valent state.
2
is a challenge faced by scientists and
a layered-type crystal lattice, and the
engineers to find means of avoiding this
18
The Electrochemical Society Interface • Spring 2006

undesirable and wasteful phenomenon.
This task requires a deep understanding
of the underlying processes involved,
which are almost always linked to
hindrances in the transport of charged
species.
A useful means of representing the
operational performance of batteries
and other energy storage and energy
conversion devices is a graph of specific
energy (A × V × h/kg = W × h/kg) vs.
specific power (W/kg). This graph is
known as a Ragone plot, and is shown
in semilog form for three common
rechargeable batteries including Ni|MH
in Fig. 3, derived from measurements
of the type shown in Fig. 2. It becomes
evident from these data, that the Li-ion
battery has twice the specific energy
compared to Ni|MH, and four times
FIG. 4. Schematic diagram of the mode of operation of a LiCoO |graphite
2
that of Ni|Cd, a system expected to
battery. During charge Li+ ions are released from LiCoO and injected into the
2
graphite lattice. The reverse processes occur during discharge.
be gradually displaced by Ni|MH, and
Li-ion, due to environmental impact
concerns. Although specific energy and

��
specific power are important, other
� � �� x� �� x � �� x ��
factors must also be considered when
� � ��
�
selecting a battery system for a specific
��
application, including reliability (critical
� �� x �� x �� x� �
� � ��
for pacemakers), safety, self-discharge,
�
temperature, and even humidity (key for
��
� � �� x�� x
Zn|air hearing aid battery). This latter
� � ��
device is a cross between a battery and a
fuel cell, in that the reaction at the (gas
FIG. 5. Single electrode and net reactions for the LiCoO |graphite Li ion battery.
permeable) cathode is the reduction of
2
oxygen from the atmosphere.

From an overall perspective, Li-ion
batteries, today’s canonical power source
for portable electronics, undoubtedly
represent the most promising energy
storage system for a host of other
applications, including transportation;
��
hence, certain aspects of its principles of
operation deserve particular attention.
0
��
Li-Ion Batteries
The discovery of transition metal
oxides, LiMO (where M = Ni or Co) as
2
Current Density, a.u.
reversible lithium-ion cathodes display-
��
ing very positive operating potentials was
made by J. Goodenough (then at Oxford,
0.0
0.5
1.0
3
.0
3.5
4.0
4.5
and currently at the University of Texas,
Austin) in the 1970s. In particular,
��
LiCoO proved a key to the development
2
and commercialization of secondary
FIG. 6. Composite, semiquantitative (arbitrary current scale) cyclic
voltammograms for natural graphite and LiMn O recorded independently at
Li-ion batteries by Sony Corp. (a non-tra-
2
4
very slow scan rates. Data were obtained in a LiPF solution in a mixture of
ditional battery company) as power
6
alkyl carbonates. The arrows indicate the direction of the potential scans and
sources for many of their own electronic
the blue and magenta represent charge and discharge, respectively. Refs: H.
devices. A schematic representation of
Wang and M. Yoshio, Journal of Power Sources 93, 123-129 (2001), and Dana
the elementary redox processes associ-
A. Totir, Boris D. Cahan and Daniel A. Scherson, Electrochimica Acta 45, 161-
166 (1999)
ated with the operation of the Li-ion bat-
tery is shown in Fig. 4. During charging,
lithium ions, Li+, are released from the
are reversed during battery discharge
carbon as a conductivity enhancer, as
LiCoO lattice to the electrolyte solu-
(see Fig. 5), which led to the coining of
well as an organic binder to provide
2
tion incorporating a suitable salt, such
such terms as rocking chair or shuttlecock
structural integrity.
as LiPF in an organic (aprotic) solvent,
to describe more graphically its mode
A technique commonly used to
6
commonly a mixture of alkyl carbonates.
of operation. The actual electrodes are
gain insight into the properties of
At the same time, Li+ ions are inserted
made of micrometer-size particles of
electrode materials, involves scanning
into the layered graphite structure from
graphite (anode) or LiCoO (cathode),
2
the electrolyte solution. These reactions
mixed with relatively high surface area
(continued on next page)
The Electrochemical Society Interface • Spring 2006
19

Batteries and
counterbalanced by the migration of
Electrochemical Capacitors
Li+ in and out of the corresponding
(continued from previous page)
lattices. It thus follows from these data,

and also confirmed experimentally,

that the operating potential of the
LiCoO2
8.25
|graphite battery is close to the
separation between the peaks associated
�

with reactions at the cathode and the
��
anode, ca. 3.7 and 0.1 V vs. Li+/Li,
8.20
3.2
3.6
4.0
4.4
��
respectively. Furthermore, that the peaks
E
0
20
40
60
80
100
��
found in the scans in the positive and

�
4.2
negative directions are nearly mirror
8.15
4.0
images is indicative that the reactions

3.8
are energetically reversible, i.e., about the
E
��
same potential difference, in principle,
8.10
3.6 0.0 0.5 1.0 1.5 2.0 2.5
nominally required to recharge the
Lattice Parameter,
��
battery.
0
20
40
60
80
100
Despite their extraordinary sensitivity,
electrochemical measurements do not
��
provide insight into the structural and
FIG. 7. Lattice parameter extracted from X-ray diffraction
electronic changes associated with the
measurements collected in situ vs. SOD (%) for Li Mn O , in the
x
2
4
redox processes involved, for example,
range 0 (fully charged) ≤ x ≤ 1 (fully discharged). The presence of two
those responsible for the multiplicity
distinct phases are represented by the blue and magenta circles. Top
of peaks found in the voltammetry in
inset: Cyclic voltammetry of LiMn O in the potential region in which
2
4
Fig. 6. Hence, other techniques must be
the redox transitions occur. Bottom inset: Potential (V vs. Li/Li+) vs.
Charge (mAh) during the C/10 discharge of the electrode. Refs: T.
used to gain access to such information.
Eriksson, A-K. Hjelm, G. Lindbergh and T. Gustafsson, Journal of
A better understanding of these factors
The Electrochemical Society, 149 (9) A1164-A1170 (2002) and Dana may be regarded as critical to the
A. Totir, Boris D. Cahan and Daniel A. Scherson, Electrochimica Acta rational design of materials displaying
45, 161-166 (1999).
optimum performance characteristics.

One approach involves a systematic
structural and spectroscopic study of a
group of lithium intercalation materials
Mn K-edg e
prepared individually spanning the entire
range of Li content of relevance to the
electrode operation, e.g., 0 ≤ x ≤ 1, for
LixCoO , where x = 0 and 1 corresponds
2
to fully charged and fully discharged

forms, respectively. Serendipitously,
this laborious endeavor can be avoided
�LiMn2O4
by combining electrochemistry, as
Li0.67 Mn2O4
an expedient and highly accurate
Normalized Absorbance
�Li0.34 Mn2O4
synthetic tool to prepare such group of
materials, with X-ray based techniques,
Li0.09 Mn2O4
such as X-ray diffraction (XRD) or
6.54
6.56
6.58
X-ray absorption spectroscopy (XAS)
as structural and electronic probes.
Energy, keV
Furthermore, advantage can be taken
FIG. 8. Series of in situ Mn K-edge X-ray absorption spectra
of the high transparency to X-rays of
(normalized absorbance vs. energy in keV) for Li Mn O for x values
x
carbon and other low-Z elements present
2
4
speciﬁed. Ref: Youhei Shiraishi, Izumi Nakai, Toshio Tsubata,
in the main electrode constituents to
Takuhiro Himeda and Fumishige Nishikawa, Journal Of Solid State
perform such measurements in situ. For
Chemistry, 133, 587- 590 (1997).
such experiments, charge is injected
the potential of a single electrode (half-
the direction of the potential scan, where into the electrodes in small increments
cell) in a linear fashion between two
blue and magenta represent charge and
and the system allowed to reach
prescribed limits first in one direction
discharge, respectively. These data were
equilibrium before data are acquired.
and then in reverse, while monitoring the acquired at very low scan rates, on the
Once completed, an additional charge
current, known as cyclic voltammetry.
order of a few tens of microvolts per
is injected, and the whole procedure
This method can be implemented with
second, to offset the sluggish diffusion
repeated until the desired Li+ range is
relative ease and provides an expedient
of Li+ through solid lattices, which are
covered. Alternatively, and depending
means of screening new materials, as
orders of magnitude smaller than those
on the time required for XRD or XAS
it requires very small quantities, even
of ions in liquid solutions, and allow
data acquisition, charge can be injected
down to a single microparticle. Shown
for quasi-equilibrium conditions to be
at a constant and small enough (low C)
in Fig. 6 are cyclic voltammograms of
achieved over the entire potential range
rate for the system to maintain quasi-
natural graphite and LiCoO recorded
explored.
equilibrium conditions, while monitoring
2
independently in a solution of LiPF in a
the potential and recording the desired
6
The clearly defined voltammetric
mixture of alkyl carbonates. The current
features are ascribed to changes in
data. These principles were fully exploited
axes in these plots are normalized for
the oxidation state of species within
for studies involving the cubic spinel
didactic purposes and the arrows indicate the electrode materials, which are
LiMn O , a “green” cathode material that
2
4
20
The Electrochemical Society Interface • Spring 2006

displays two well-defined voltammetric
peaks at about 4.0 V vs. Li/Li+ (top
inset, Fig. 7). Analysis of a series of X-
ray diffractograms for the (111) peak of
LiMn O collected in situ during the C/10
2
4
discharge of the fully charged (λ-MnO )
2
cathode (bottom inset, Fig. 7), yielded, as
shown in Fig. 7, evidence for the presence
of one single phase (blue circles) for
states of discharge (SOD), defined as the
percent of the total capacity consumed,
higher than 35%, and another single
phase (magenta circles) for SOD < 10%,
for which the lattice parameter varied
linearly with SOD. As indicated in the
figure, these two phases coexist for 10 <
SOD < 35%.
Information regarding the oxidation
state of the Mn sites as a function of
SOD can be obtained from in situ XAS
spectra, a technique in which the
FIG. 9. (top) Schematic representation of a charged electrochemical
energy of the radiation is scanned over
capacitor and double layers at both electrode|electrolyte interfaces. Note that
the device is two double layers in series, one at each electrode|electrolyte
the range embracing the excitation of
interface. Blue and magenta shades refer to net negative and positive
core, e.g., 1s, electrons to higher lying
charges. (bottom) Schematic representation of a charged high area carbon
levels, including photoionization, or
capacitor. The lines around the carbon (gray) particles represent either
K-edge. Shown in Fig. 8 are a series of
positive (magenta) or negative (blue) charges. Positive and negative ions
Mn K-edge XAS spectra in the form of
(circles) are in pink and light blue, respectively.
normalized absorbance vs. energy (keV)
for Li Mn O for x in the range 0 ≤ x ≤ 1
x
2
4

recorded in situ in a specially designed
3.0
spectroelectrochemical cell. As the
2.5
electronic density of the metal decreases,
by virtue of an increase in the oxidation
2.0
�
state, the nucleus becomes more effective
1.5
in attracting the remaining electrons,

1.0
making it more difficult for electrons in
E cell,
the same orbital to be removed. Hence,
0.5
as the experimental data shows, the
0.0
charging of the material leads to a shift
0
100
200
300
400
500
in the energy required to photoexcite
the 1s electrons toward higher energies,
��

providing evidence that the electrons
involved have predominantly metal
FIG. 10. Voltage proﬁ les for the constant current charge (light blue) and discharge
character.
(pink) of a high area carbon electrochemical capacitor incorporating an organic
solvent.
Electrochemical Capacitors
Batteries (and also fuel cells) rely on
chemical reactions at the electrodes to
the electrode and the other is a collec-
should provide a capacity of 200 F, which
generate electrical energy. The behavior
tion of ions present in the electrolyte,
could be matched only by a conventional
of certain electrode-electrolyte interfaces,
forming a diffuse double layer of only a
capacitor of much larger dimensions.
however, resembles that of a conven-
few nanometers thick (see Fig. 9 top for a
Advantage has been taken of this
tional capacitor in that charge transfer
schematic representation of a completly
phenomenon to develop electrochemical
across the interface over a limited voltage
charged double layer capacitor). To pre-
capacitors based purely on carbon and
range, up to ca. 3 V, is greatly impaired.
serve interfacial electroneutrality, the
suitable electrolytes with exceedingly
Even though the potential should be
total charge of this diffuse layer must
high capacitances per unit weight or
thermodynamically sufficient to drive
be equal and opposite to that which
volume (see Fig. 9 bottom for a schematic
one or more electron transfer processes,
resides on the electrode. The actual spe-
representation of a charged carbon
the rates at which such reactions proceed
cific double layer capacitance of solid
based capacitor). Note that the storage
are negligibly small rendering the inter-
electrode|aqueous solution interfaces, C ,
device is comprised of two (interfacial)
dl
face as effectively charged. Exceedingly
is on the order of a few tens of µF/cm2,
capacitors connected in series. As a
careful experiments performed by
and thus much higher than those found
means of illustration, constant current
Grahame toward the middle of this past
for conventional capacitors, and a func-
charging (or discharging) of a high area
century laid the foundations of our cur-
tion of the nature of both the electrode
carbon capacitor incorporating identical
rent knowledge of electrified interfaces.
and the electrolyte solution.
electrodes immersed in an organic
Key to the success of his experiments was
Carbon is an unusual material in
electrolyte elicits a linear increase (or
the use of Hg electrodes, for which the
that forms displaying very high specific
decrease) in the cell potential, E ,
cell
surface could be renewed thereby avoid-
areas, up to 2000 m2/g, can be produced
with time (see Fig. 10), as expected
ing problems with impurities. According
inexpensively. Assuming a C of ca. 10
for a conventional capacitor. The very
to theory, one plate of the capacitor is
dl
µF/cm2, a gram of such high-area carbon
(continued on next page)
The Electrochemical Society Interface • Spring 2006
21

Batteries and
Electrochemical Capacitors
(continued from previous page)
FIG. 11. Ragone plots for an array of energy storage and energy conversion devices. Ref: Venkat
Srinivasan and John Newman: http://berc.lbl.gov/venkat/Ragone-construction.pps.
and an Associate Editor for the Journal of The
small vertical traces that are observed
dimensional batteries incorporating
Electrochemical Society. He may be reached at
Daniel.scherson@case.edu.
immediately following application or
components of nanometric dimensions
reversal of the current are due to voltage
arranged in interpenetrating networks,
ATTILA PALENCSÁR is a native of Romania and
received his BS in chemistry at Babes-Bolyai
losses attributed to the internal resistance
to take advantage of short diffusional
University in Cluj Napoca, Romania. He is
of the device or IR loss.
paths and thus higher currents
currently pursuing his PhD at Case Western
An appreciation of the advantage
than those achievable with present
Reserve University under the supervision of Daniel
Scherson. He may be reached at iap@case.edu.
such an electrochemical capacitor,
technologies. The advent of novel
often referred to in the popular press as
theoretical approaches and powerful
supercapacitor or ultracapacitor, offers
computers is expected to deepen
compared to batteries can be gleaned
further our understanding of the factors
from the Ragone plot. As shown in Fig.
that control both the energetics and
11, electrochemical capacitors have
transport dynamics of ions within
superb specific power compared to
well defined lattices. Such efforts are
batteries, but modest specific energies.
being complemented by ingenious
This translates, in transportation
tactics in combinatorial chemistry and
terms, as good acceleration but poor
simultaneous high-throughput screening
range, which is precisely opposite to
of multiple electrodes that could well
batteries or fuel cells, which are yet
lead to the discovery of materials
another type of electrochemical device
displaying unsuspected properties.

in which the reactants are added to the
Acknowledgments
electrodes to generate electricity (see
contribution in this Interface issue from
The authors express their deep
the Energy Technology Division). From
appreciation to N. Dudney, G. Blomgren,
practical and technological viewpoints,
K. M. Abraham, B. Miller, R. Middaugh,
electrochemical capacitors are robust
R. Brodd, G. Amatucci, J. Miller,
devices with excellent cycle life that can
S. Sarangapani, and R. Corn for a critical
improve the effectiveness of battery-
reading of the manuscript.
based systems by shrinking the volume
Suggested Readings
of batteries required and reducing the
frequency of their replacement.
1. Handbook of Batteries, 3rd ed.,
D. Linden and T. B. Reddy, Editors,
Whether a battery, an electrochemical
McGraw-Hill, New York (2002).
capacitor, a fuel cell, or a judicious
combination of two or more of these,
2. B. E. Conway, Electrochemical
the level of sophistication involved
Supercapacitors: Scientific Fundamentals
in the design and manufacturing
and Technological Applications, Kluwer
of a power source for a specific
Academic/Plenum Publishing, New
application, including microelectronics,
York (1999).
transportation, and larger scale
About the Authors
stationary stacks over the next few years
may well approach the same degree
DANIEL SCHERSON is the Director of the Ernest B.
of complexity as the devices they will
Yeager Center for Electrochemical Sciences and
the Charles F. Marbery Professor of Research in
power. A particularly intriguing prospect
Chemistry at Case Western Reserve University. He
is the possibility of constructing three
is currently the chair of the ECS Battery Division
22
The Electrochemical Society Interface • Spring 2006