Abstract: A lithium-seawater battery is being developed for undersea sensors and vehicles. This new energy source promises significantly higher energy density than Commercial Off the Shelf (COTS) primary batteries for air independent, undersea operations. The critical enabler for this effort is a water and gas impermeable, glass-ceramic electrolyte (GCE). The electrolyte provides an ionic pathway between lithium and seawater and it prevents direct contact between them. As a result, anodes made with GCEs have shown high voltage and high efficiency in aqueous electrolytes. The lithium metal anode is encased in a collapsible pouch composed of a flexible laminate and a thin (250 μm) glass-ceramic electrolyte “window”. The aluminum foil based laminate is impermeable to water and atmospheric gases. A metal tab protrudes from the pouch as an electrical lead and a non aqueous Li-ion electrolyte fills the gap between Li and the ceramic membrane. Critical elements for high efficiency and high voltage are low pouch permeability (keeping water and atmospheric gases out and nonaqueous electrolyte in), the shape of the pouch with respect to collapse and pressure tolerance, and the electrochemical performance of the GCE pouch anodes in seawater. Keywords: Lithium Primary Battery; Seawater Battery; Li Ion Conducting Ceramic; 2 1 power-sources_lisfc

1. Lithium-Seawater Battery for Undersea Sensors and Vehicles
Christian R. Schumacher1
, Charles J. Patrissi*1
, Steven P. Tucker2
1- Naval Undersea Warfare Center (NUWC)
1176 Howell Street
Newport, RI 02841
2-Science Application International Corp. (SAIC)
28 Jacome Way
Middletown, RI 02842
*Tel: 401.832.4242, charles.patrissi@navy.mil
Abstract: A lithium-seawater battery is being developed for
undersea sensors and vehicles. This new energy source promises
significantly higher energy density than Commercial Off the Shelf
(COTS) primary batteries for air independent, undersea
operations. The critical enabler for this effort is a water and gas
impermeable, glass-ceramic electrolyte (GCE). The electrolyte
provides an ionic pathway between lithium and seawater and it
prevents direct contact between them. As a result, anodes made
with GCEs have shown high voltage and high efficiency in
aqueous electrolytes. The lithium metal anode is encased in a
collapsible pouch composed of a flexible laminate and a thin (250
µm) glass-ceramic electrolyte “window”. The aluminum foil
based laminate is impermeable to water and atmospheric gases.
A metal tab protrudes from the pouch as an electrical lead and a
non aqueous Li-ion electrolyte fills the gap between Li and the
ceramic membrane. Critical elements for high efficiency and high
voltage are low pouch permeability (keeping water and
atmospheric gases out and nonaqueous electrolyte in), the shape
of the pouch with respect to collapse and pressure tolerance, and
the electrochemical performance of the GCE pouch anodes in
seawater.
Keywords: Lithium Primary Battery; Seawater Battery;
Li Ion Conducting Ceramic;
Introduction
Development of affordable, safe and environmentally compatible
energy sources for Autonomous Undersea Systems (AUS)
propulsion and hotel power continues to be an important goal of
the U.S. Department of the Navy (DON). Power source
requirements include: high energy density, air-independence,
pressure tolerance, and robust performance while maintaining
minimal signature, reasonable cost/safety and a long shelf life.
Lithium seawater batteries have been investigated due to the high
energy density of lithium and abundant supply of seawater
catholyte for undersea applications. Lithium has the highest
voltage (3.04V) and capacity (3.86 Ah/kg) of all metallic anode
materials, while seawater can be metered into the battery as
necessary, significantly contributing to battery energy density.
The discharge reactions for the lithium water battery are as
follows:
Anode:
Li → Li+
+ e-
3.05 V (1)
Cathode:
H2O + e-
→ ½ H2 + OH-
-0.83 V (2)
Overall:
Li + H20 → Li+
+ OH-
+ ½ H2 2.22 V (3)
The overall electrochemical reaction has a thermodynamic
potential of 2.22 V and a theoretical specific energy of 8530 Wh/
kg based on lithium, which is the only reactant that has to be
supplied with the battery.
For efficient utilization of lithium, the parasitic corrosion reaction
with water must be minimized or eliminated. Once initiated, this
highly exothermic reaction (-53.3 kJ/ g-mol of lithium) can further
accelerate corrosion. Additionally, to ensure adequate shelf life,
the lithium anode must be protected from ambient oxygen,
nitrogen and water, which can cause corrosion or passivation of
the lithium anode surface.
Historically, protection of the lithium anode has been
accomplished by the use of a hydroxyl (OH-) ion at concentrations
greater than 1.5M, which forms a dynamic protective LiOH film.
1-6
The film prevents short circuits, but allows high current
densities (> 0.2 to 0.4 kA/m2). The control of this film is
accomplished by an electrolyte management subsystem and
internal cell features such as a reservoir, pump, heat exchanger,
and flowing electrolyte controller. The rate of discharge is
inversely proportional to the concentration of electrolyte, with cell
power controlled by adjusting molarity of the LiOH at the
anode[1]. In practice these batteries are shown to be complicated
to manage and control. Prototype Li-water batteries designed for
high7
and low rate8
operation were demonstrated using hydroxide
catholytes.
More recently, Glass Ceramic Electrolytes (GCEs) 9-14
have been
developed in an effort to physically separate Li and water while
maintaining ionic contact between them. The solid state Li+
conductivity (10-4
S/cm) of GCEs limits rate performance,
however, they are water impermeable so parasitic Li corrosion is
eliminated. In addition, GCE electrical conductivity is low (< 10-
11
S/cm) which prevents self discharge after the battery is
activated. Anodes for Li-water batteries have been developed
which encase the Li anode inside a flexible, hermetic pouch.15-17
A GCE “window” provides ionic contact with the aqueous
catholyte.
Figure 1 shows a conceptual drawing of a Li-water battery with a
seawater catholyte. Typically, the metal anode is isolated from
seawater by a pouch composed of a flexible laminate barrier film
which is adhered to the GCE. A Li ion conductive separator is
used between the Li and GCE to prevent a possible reduction
reaction between Li and certain oxides present in the ceramic.15
Gas and hydroxide ion are produced at the cathode during battery
discharge. In principle, battery operation is simple and efficient.
The key to long service and shelf life, and high Li coulombic
efficiency, is low pouch permeability. The reported open circuit
potential of Li/GCE anodes in aqueous electrolytes is 3.04 V vs.
SHE, indicating no mixed potential and therefore no reaction with
water. Coulombic efficiencies > 96+% have also been reported
for Li/CGE anodes in aqueous electrolytes.

2. Catholyte:
Sea Water
Li Metal
e-e-
Li+
Li+
H2
OH-
H2O
Li+ Conducting Glass
Ceramic Electrolyte
Current
Collector
(Cathode
Reaction
Surface)
Flexible Film
Proprietary
Interlayer
LOAD
OH-
Catholyte:
Sea Water
Li Metal
e-e-
Li+
Li+
H2
OH-
H2O
Li+ Conducting Glass
Ceramic Electrolyte
Current
Collector
(Cathode
Reaction
Surface)
Flexible Film
Proprietary
Interlayer
Catholyte:
Sea Water
Li Metal
Catholyte:
Sea Water
Li Metal
Catholyte:
Sea Water
Li Metal
e-e-
Li+
Li+
H2
OH-
H2O
Li+ Conducting Glass
Ceramic Electrolyte
Current
Collector
(Cathode
Reaction
Surface)
Flexible Film
Proprietary
Interlayer
LOAD
OH-
Figure 1. Schematic Diagram of Li Seawater Battery
NUWC’s Lithium Water Battery Design
The Naval Undersea Warfare Center (NUWC), in Newport, RI,
has been investigating Li-ion conducting Glass Ceramic
Electrolytes since 2005 and developing a Lithium Seawater
Battery since 2006.
NUWC’s design of a pressure tolerant GCE-based lithium pouch
anode is shown in Fig. 2. The pouch consists of a GCE sealed in a
flexible barrier laminate, a metallic lithium slug, a polymeric
battery separator, current collector lead, and a proprietary liquid
interlayer. The contoured “bellows” shape allows for pouch
collapse, as lithium is conducted thru the ceramic, with minimal
pressure differential between the incompressible interior
components and sea water exterior. NUWC has demonstrated
successful pouch collapse with >96% Li utilization.
The Li seawater battery is a reserve battery since there is no
cathode present during storage. For this reason the battery
promises long shelf life (no shelf discharge) and it is potentially
safer to store than commercial off the shelf (COTS) Li batteries.
One limitation is the relatively poor rate performance of the GCE
which directs its use toward low power applications.
Potting
Material
Ni Wire Lead
Glass Ceramic Membrane
Lithium Anode Slug
Ni Foil
G-LAM
Potting
Material
Ni Wire Lead
Glass Ceramic Membrane
Lithium Anode Slug
Ni Foil
G-LAM
Figure 2. Design of GCE Single Cell Pouch
An example of a proposed battery is shown in Fig. 3, which
consists of efficiently packed layers of anode pouches and cathode
screens connected in parallel to reach the specific application’s
required power level. Series connection of anode pouches/
cathodes can prove problematic due to leakage currents arising
from immersion in a common catholyte (sea water). Current
configuration limitations are due to the low yield of larger
dimensioned GCE plates.
Figure 3. Battery Configuration
Battery Design Improvements
Two principle GCEs are under study at NUWC, both are
manufactured by Ohara Corp. (Rancho Santa Margarita, CA).
Both membranes are based on Ohara’s Lithium-Ion Conducting
Glass-Ceramic (LIC-GC). This material exhibits high Li-ion
conductivity for a solid electrolyte (1.2 x 10 -3
S/cm at STP).
The nonporous GCEs are prepared by two methods. The AG01
material is prepared by casting an amorphous block from molten
precursors and then cutting, sintering and polishing the wafers to
thickness (75 to 350 um thick). The second processing method is
to tape cast the LIC-GC powder.
The AG01 formulation results in a fully dense membrane, with
close dimensional tolerance and a consistent surface finish.
Membranes are available in thickness 50, 75, 150, and 300 um
and outside diameters of 1” and 2”. The final conductivity in plate
form is 1 x 10 -4
S/cm.
However, the AG01 membrane processing has a fairly high cost
due to labor intensive grinding and polishing steps. Also the
larger dimension membranes (>2”OD) are problematic due to
lower yields during the final grinding and polishing steps.
The tape casting process is less labor intensive and allows for
greater geometrical scale up. Tape cast membranes are available
between 50 and 300 µm and up to 3” OD. Larger diameters (>3”)
should be possible. This processing technique requires a small
amount of binder to allow handling in the “green” form. These
binders are burned off during sintering. Recent formulations have
resulted in greater conductivity compared to AG01 (2 x 10 -4
S/cm). At present tape cast membranes show lower mechanical
strength and poorer seawater longevity than the AG01 version.

3. A small scale prototype manufacturing line has been set up at
NUWC in a humidity controlled (<0.5% relative humidity) dry
room to fabricate pouch anodes incorporating both AG01 and tape
cast Ohara membranes. Development and scale up of 1”, 2” and
3” OD GCE is ongoing. Packaging, design, fabrication and
testing are all performed in-house with limited contractor support.
Fig 4, shows NUWC’s Generation II, 2”OD GCE pouch anode.
These pouches have been tested to >96% Lithium utilization and
show anode half cell voltages of -2.5 vs Ag/AgCl at 2 mA/ cm2
current density.
Electrolyte fill port Ni foil current collector
Ceramic electrolyte membrane
Collapsible
foil pouch
Electrolyte fill port Ni foil current collector
Ceramic electrolyte membrane
Collapsible
foil pouch
Figure 4. Gen II Pouch Design
A limitation of the Gen II design is the Ni Foil current collector.
The disc shaped current collector offered a good solution to fill the
relief hole necessary to form the pouch to required depth.
However, the Ni disc must be post-potted to isolate the battery
from the seawater environment. This potting adds an additional
step, limits efficient packing of pouches, and could be a potential
leakage path.
Experimentation and optimization of the foil laminates and
forming processes has led to NUWC’s Generation III, pouch
design (Fig. 5). This iteration focused on reconfiguring the
current collector lead to a radial tab, thereby reducing pouch seals
and potential leakage paths from 3 to 2. This also eliminated a
post fabrication potting step to cover the original foil current
collector.
Figure 5. Gen III Pouch Design
An example of a fully discharged pouch is shown in Fig. 6. This
AG01 GCE pouch anode was discharged in ASTM seawater for
950 hours (~40 days) under a varying current load. The
redesigned pouch demonstrates full collapse at high lithium
utilizations (96+%) under ambient pressures.
Figure 6. Gen III Pouch Design
Electrochemical Testing & Results
Electrochemical testing is performed using several commercially
available pieces of testing equipment on site at NUWC. An
EG&G 362 Potentiostat is used for long duration constant current/
constant voltage experiments and as well as limited polarization
work. A Princeton Applied Research (PAR) (now Biologic)
VMP2Z potentiostat/ galvanostat was used for polarization and
impedance experiments.
A typical anode pouch discharge experiment begins with an Open
Circuit Voltage (OCV) reading to verify proper functioning of the
anode, i.e., no gross leakage or mixed voltage potential. A
normally operating pouch anode will have an OCV of 3.05 vs
SHE. Next a stepwise constant current polarization experiment is
executed over the range of: 0.25, 0.5, 1.0, 2.0, and 3.0 mA/ cm2.
Voltage transients are typical over the first several minutes of a
current density step, indicating a changing impedance with time
until the flat voltage plateau is reached. A representative
polarization curve is shown in Fig. 7. The origin of the transient
voltage decay is unknown.
-3.2
-3.0
-2.8
-2.6
-2.4
-2.2
-2.0
-1.8
-1.6
0 10 20 30 40 50 60
Time [Hrs]
AnodeVoltage[VvsSHE]
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
CurrentDensity[mA/cm2]
AG01 voltage AG01 current Density
Figure 7. Rate performance of pouch anodes
prepared with tape cast and AG01 type ceramic
electrolyte membranes. Current (lower Square line) or
Voltage (upper line).
The plateau voltage value for each constant current density range
is plotted to generate a Voltage-Current curve (V-I Curve).
Typical V-I curve for both a Tape Cast and AG01 based pouch
anodes are shown in Fig. 8. A tape cast membrane shows better
half cell anode voltage than a similar dimension AG01 membrane.
This is attributed to the higher conductivity of the tape cast
membrane. Based on the V-I curve. The V-I curve is used to
project energy and power density numbers for a configured
Lithium Seawater battery. Battery current densities of 0.5, 1.0, and
2.0 mA/ cm2
are nominally referred to as low, mid and high
current discharges, respectively.
-3.5
-3.0
-2.5
-2.0
-1.5
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Current Density [mA/ cm2]
AnodeVoltage[VvsSHE]
Tape Cast AG01

4. Figure 8. Polarization of a Li pouch anode with an
AG01 ceramic electrolyte membrane
Long term testing is conducted either as a constant current or
constant voltage experiment. Fairly flat and constant performance
is typically seen over 50 to 75% of a full pouch discharge cycle.
Power fade is typical in the last third of the discharge cycle for
both Tape cast and AG01 anodes. Fig. 9 shows a representative
anode power vs. time discharge profile for both tape cast and
AG01 based anode pouches.
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100
Li Utilization [%]
AnodePowerDensity[mW/cm2]
Tape Cast AG01
Figure 9.. Power density of pouch anodes as a
function of Li utilization. Tape cast (upper line) or
AG01 (lower line).
Lithium utilization is calculated by comparing the charge passed
to the number of equivalents of charge contained in the Li metal
anode in the pouch. Percent lithium utilizations numbers, on a
mass basis and Faraday’s law basis, of some recent tests are given
in Table 1
Table 1. Lithium Utilization Results of Gen III Pouch
Anodes
Membrane
Type
Membrane
Thickness
[um]
Lithium
Post
Test
[grams]
Li Utilization [%]
Li
Mass
Faraday’s
Law
AG01 250 0.10 97.5 95.2
AG01 250 0.21 94.8 97.7
AG01 250 0.05 98.8 99.3
Tape Cast 350 0.08 98.0 99.0
Future Work
Future investigations include studying the effects of membrane
thickness, temperature, electrolytes and cathode materials.
Additionally scale up to 3” and larger investigation of new GCEs
will be performed Finally the long term shelf life and stability and
robustness of the pouch anode are being studied.
Acknowledgements
This work was supported by NAVSEA and Office of Naval
Research (ONR) 33, Dr. Michelle Anderson.
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