U.S. patent application number 13/169487 was filed with the patent office on 2012-03-01 for electrolyte flow configuration for a metal-halogen flow battery.
This patent application is currently assigned to Primus Power Corporation. Invention is credited to Jonathan L. Hall, Gerardo Jose la O', Pallavi Pharkya, Rick Winter.
Application Number | 20120052340 13/169487 |
Document ID | / |
Family ID | 45697665 |
Filed Date | 2012-03-01 |
United States Patent
Application |
20120052340 |
Kind Code |
A1 |
la O'; Gerardo Jose ; et
al. |
March 1, 2012 |
Electrolyte Flow Configuration for a Metal-Halogen Flow Battery
Abstract
A flow battery and method of operating a flow battery. The flow
battery includes a first electrode, a second electrode and a
reaction zone located between the first electrode and the second
electrode. The flow battery is configured with a first electrolyte
flow configuration in charge mode and a second flow configuration
in discharge mode. The first electrolyte flow configuration is at
least partially different from the second electrolyte flow
configuration.
Inventors: |
la O'; Gerardo Jose;
(Alameda, CA) ; Winter; Rick; (Orinda, CA)
; Hall; Jonathan L.; (San Mateo, CA) ; Pharkya;
Pallavi; (Fremont, CA) |
Assignee: |
Primus Power Corporation
Hayward
CA
|
Family ID: |
45697665 |
Appl. No.: |
13/169487 |
Filed: |
June 27, 2011 |
Current U.S.
Class: |
429/51 ;
429/70 |
Current CPC
Class: |
H01M 12/085 20130101;
Y02E 60/10 20130101 |
Class at
Publication: |
429/51 ;
429/70 |
International
Class: |
H01M 10/44 20060101
H01M010/44; H01M 2/38 20060101 H01M002/38; H01M 8/18 20060101
H01M008/18 |
Claims
1. A flow battery, comprising: a first electrode; a second
electrode; a reaction zone located between the first electrode and
the second electrode, wherein: the flow battery is configured with
a first electrolyte flow configuration in charge mode and a second
flow configuration in discharge mode; and the first electrolyte
flow configuration is at least partially different from the second
electrolyte flow configuration; a charge mode electrolyte inlet
configured to provide at least a portion of the electrolyte into
the reaction zone in the charge mode; a discharge mode electrolyte
inlet configured to provide at least a portion of the electrolyte
into the reaction zone in the discharge mode, wherein the discharge
mode electrolyte inlet is different from the charge mode
electrolyte inlet; and a common charge and discharge mode
electrolyte outlet configured to provide the electrolyte out of the
reaction zone in the charge and the discharge modes.
2. (canceled)
3. (canceled)
4. The flow battery of claim 1, wherein: the first electrode
comprises a permeable electrode which serves as a positive
electrode in the discharge mode; and the second electrode comprises
an impermeable, oxidizable metal electrode which serves as a
negative electrode in the discharge mode.
5. The flow battery of claim 4, wherein: the charge mode
electrolyte inlet is located in the reaction zone between the first
and the second electrodes; the discharge mode electrolyte inlet is
located outside the reaction zone adjacent to a surface of the
first electrode facing away from the reaction zone; and the common
electrolyte outlet is located in the reaction zone between the
first and the second electrodes.
6. The flow battery of claim 5, wherein: the charge mode
electrolyte inlet is connected to plural charge mode inlet channels
in a first surface of a first frame supporting at least one
electrode of the cell; the discharge mode electrolyte inlet is
connected to plural discharge mode inlet channels in a second
surface of the first frame opposite to the first surface of the
frame; and the common electrolyte outlet is connected to plural
outlet channels in the first surface of the frame.
7. The flow battery of claim 6, wherein: the flow battery comprises
a vertical stack of horizontal flow cells electrically connected in
series, and a stack of frames supporting the stack of flow cells;
each flow cell comprises one first electrode and one second
electrode; the plural charge mode inlet channels are connected to a
charge mode inlet manifold formed by first aligned openings in the
stack of frames; the plural discharge mode inlet channels are
connected to a discharge mode inlet manifold formed by second
aligned openings in the stack of frames; the plural outlet channels
are connected to a common outlet manifold formed by third aligned
openings in the stack of frames; the stack of flow cells is located
separately from a reservoir containing a first volume and a second
volume; the first electrode comprises a porous ruthenized titanium;
and the second electrode comprises titanium that is coated with
zinc during the charge mode.
8. The flow battery of claim 7, further comprising: a charge mode
pump connected to the charge mode inlet manifold; a discharge mode
pump connected to the discharge mode inlet manifold; at least one
bypass channel in the second surface of the frame which is
connected to the common outlet manifold; plural conductive spacers
which electrically connect the first electrode of one flow cell in
the stack with the second electrode of an adjacent flow cell in the
stack; and plural flow channels located between the conductive
spacers and above the first electrodes in each cell, such that the
discharge mode electrolyte inlet is connected to the plural flow
channels.
9. The flow battery of claim 5, wherein: the charge mode
electrolyte inlet is configured to provide all of the electrolyte
into the reaction zone in the charge mode and the discharge mode
electrolyte inlet is configured to provide no electrolyte into the
reaction zone in the charge mode; and the discharge mode
electrolyte inlet is configured to provide all or a portion of the
electrolyte into the reaction zone in the discharge mode and the
charge mode electrolyte inlet is configured to provide no
electrolyte or a portion of the electrolyte into the reaction zone
in the discharge mode.
10-20. (canceled)
21. A method of operating a flow battery comprising: flowing an
electrolyte in a first flow configuration in charge mode and a
second flow configuration in discharge mode, wherein the first flow
configuration is at least partially different from the second flow
configuration; and wherein: the flow battery comprises a flow cell
including a first electrode, a second electrode, and a reaction
zone located between the first electrode and the second electrode.
in the charge mode, the electrolyte is provided from a charge mode
electrolyte inlet into the reaction zone, and from the reaction
zone into a common electrolyte outlet; in the discharge mode, at
least a portion of the electrolyte is provided from a discharge
mode electrolyte inlet into the reaction zone, and from the
reaction zone into the common electrolyte outlet; and the discharge
mode electrolyte inlet is different from the charge mode
electrolyte inlet.
22. (canceled)
23. The method of claim 21, wherein: the first electrode comprises
a permeable electrode which serves as a positive electrode in the
discharge mode; and the second electrode comprises an impermeable,
oxidizable metal electrode which serves as a negative electrode in
the discharge mode.
24. The method of claim 21, wherein: the charge mode electrolyte
inlet is located in the reaction zone between the first and the
second electrodes; the discharge mode electrolyte inlet is located
outside the reaction zone adjacent to a surface of the first
electrode facing away from the reaction zone; and the common
electrolyte outlet is located in the reaction zone between the
first and the second electrodes.
25. The method of claim 24, wherein: the first flow configuration
is different from the second flow configuration in the flow cell;
in the charge mode, all of the electrolyte is provided from the
charge mode electrolyte inlet into the reaction zone in the charge
mode and no electrolyte is provided into the reaction zone through
the first electrode from the discharge mode electrolyte inlet; and
in the discharge mode, all or a portion of the electrolyte is
provided from the discharge mode electrolyte inlet through the
first electrode into the reaction zone and no electrolyte or a
portion of the electrolyte is provided from the charge mode
electrolyte inlet into the reaction zone.
26-29. (canceled)
30. The method of claim 23, wherein: the electrolyte comprises a
metal halide electrolyte; the flow cell is located in a stack of
flow cells; and the stack of flow cells is located separately from
a reservoir containing a first volume and a second volume; and
further comprising pumping the metal-halide electrolyte between the
reservoir and the stack of flow cells in the charge and the
discharge mode using at least one pump.
31. (canceled)
32. The method of claim 30, wherein the first electrode comprises a
porous ruthenized titanium, the second electrode comprises zinc
plated titanium, and the stack comprises a vertical stack of
horizontal flow cells connected in series.
33. The method of claim 21, wherein the flow battery operates with
a higher voltaic and columbic efficiency than the same battery
operating with the same first and second flow configurations.
34-36. (canceled)
37. The method of claim 24, wherein: in the charge mode: (a) all of
the electrolyte is provided from the charge mode electrolyte inlet
into the reaction zone; and (b) the electrolyte is provided from
the reaction zone into the common electrolyte outlet through both
of: (i) a charge mode electrolyte outlet located in the reaction
zone between the first and the second electrodes; and (ii) the
first electrode and a bypass conduit located outside the reaction
zone adjacent to a surface of the first electrode facing away from
the reaction zone; and (c) no electrolyte is provided into the
reaction zone through the first electrode from the discharge mode
electrolyte inlet; and in the discharge mode: (a) all of the
electrolyte is provided from the discharge mode electrolyte inlet
into both of: (i) into the reaction zone through the first
electrode; and (ii) directly into the bypass conduit; (b) the
electrolyte is provided from the reaction zone into the common
electrolyte outlet through the charge mode electrolyte outlet; and
(c) no electrolyte is provided from the charge mode electrolyte
inlet into the reaction zone.
Description
FIELD
[0001] The present invention is directed to electrochemical systems
and methods of using same.
BACKGROUND
[0002] The development of renewable energy sources has revitalized
the need for large-scale batteries for off-peak energy storage. The
requirements for such an application differ from those of other
types of rechargeable batteries such as lead-acid batteries.
Batteries for off-peak energy storage in the power grid generally
are required to be of low capital cost, long cycle life, high
efficiency, and low maintenance.
[0003] One type of electrochemical energy system suitable for such
an energy storage is a so-called "flow battery" which uses a
halogen component for reduction at a normally positive electrode,
and an oxidizable metal adapted to become oxidized at a normally
negative electrode during the normal operation of the
electrochemical system. An aqueous metal halide electrolyte is used
to replenish the supply of halogen component as it becomes reduced
at the positive electrode. The electrolyte is circulated between
the electrode area and a reservoir area. One example of such a
system uses zinc as the metal and chlorine as the halogen.
[0004] Such electrochemical energy systems are described in, for
example, U.S. Pat. Nos. 3,713,888, 3,993,502, 4,001,036, 4,072,540,
4,146,680, and 4,414,292, and in EPRI Report EM-I051 (Parts 1-3)
dated April 1979, published by the Electric Power Research
Institute, the disclosures of which are hereby incorporated by
reference in their entirety.
SUMMARY
[0005] An embodiment relates to a flow battery. The flow battery
includes a first electrode, a second electrode and a reaction zone
located between the first electrode and the second electrode. The
flow battery is configured with a first electrolyte flow
configuration in charge mode and a second flow configuration in
discharge mode. The first electrolyte flow configuration is at
least partially different from the second electrolyte flow
configuration.
[0006] Another embodiment relates to a method of operating a flow
battery. The method includes flowing an electrolyte in a first flow
configuration in charge mode and a second flow configuration in
discharge mode. The first flow configuration is at least partially
different from the second flow configuration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 illustrates a side cross section view of an
embodiment of the electrochemical system with a sealed container
containing a stack of electrochemical cells.
[0008] FIG. 2 illustrates a side cross section view of flow paths
in a stack of horizontally positioned cells.
[0009] FIG. 3A is a plan view of a first, charge side of a frame
for holding the horizontally positioned cells illustrated in FIG.
2.
[0010] FIG. 3B is a plan view of a second, discharge side of the
frame illustrated in FIG. 3A.
[0011] FIG. 4 is a plan view illustrating details of the portion
"A" of a flow channel of FIG. 3A.
[0012] FIG. 5 is a cross section of a stack of electrochemical
cells through the line A'-A' in FIG. 3A.
[0013] FIG. 6 is a cross section of a stack of electrochemical
cells through the line B'-B' in FIG. 3A.
[0014] FIG. 7 is a cross section of a stack of electrochemical
cells through the line C'-C' in FIG. 3B.
[0015] FIG. 8 illustrates a side cross section of an embodiment of
an electrolyte flow configuration during charge mode. The
electrolyte flow is configured for 100% flow-by flow.
[0016] FIG. 9A illustrates a side cross section of another
embodiment of an electrolyte flow configuration during charge mode.
The electrolyte flow is configured for majority flow-by flow and
minority flow-through flow.
[0017] FIG. 9B illustrates a side cross section of another
embodiment of an electrolyte flow configuration during charge mode.
The electrolyte flow is configured for minority flow-by flow and
majority flow-through flow.
[0018] FIG. 9C illustrates a side cross section of another
embodiment of an electrolyte flow configuration during charge mode.
The electrolyte flow is configured for majority flow-by flow with
minority flow-through flow up through the porous electrode. In
contrast to the embodiment illustrated in FIG. 9A, the minority
flow-through flow exits the cell through a bypass.
[0019] FIG. 9D illustrates a side cross section of an embodiment of
an electrolyte flow configuration during charge mode. The
electrolyte flow is configured for minority flow-by flow and
majority flow-through flow up through the porous electrode. In
contrast to the embodiment illustrated in FIG. 9B, the majority
flow-through flow exits the cell through a bypass.
[0020] FIG. 10 illustrates a side cross section of an embodiment of
an electrolyte flow configuration during discharge mode. The
electrolyte flow is configured for 100% flow-through flow.
[0021] FIG. 11A illustrates a side cross section of an embodiment
of an electrolyte flow configuration during discharge mode. The
electrolyte flow is configured for majority flow-through flow and
minority flow-by flow.
[0022] FIG. 11B illustrates a side cross section of another
embodiment of an electrolyte flow configuration during discharge
mode. The electrolyte flow is configured for majority flow-by flow
and minority flow-through flow.
[0023] FIG. 12A illustrates a side cross section of an embodiment
of an electrolyte flow configuration with segmented electrodes in
charge mode with 100% flow-by flow.
[0024] FIG. 12B illustrates a side cross section of an embodiment
of an electrolyte flow configuration with segmented electrodes in
discharge mode with 100% flow-through flow.
[0025] FIG. 12C illustrates a side cross section of an embodiment
of an electrolyte flow configuration with segmented electrodes in
charge mode with flow-by and flow-through flow and partial exit
flow through a bypass.
[0026] FIG. 13A is a plan view of a first, charge side of a frame
of an alternative embodiment for holding the horizontally
positioned cells illustrated in FIG. 2.
[0027] FIG. 13B is a plan view of a second, discharge side of the
frame of the alternative embodiment illustrated in FIG. 13A.
[0028] FIG. 13C is a schematic diagram of components of the
electrochemical system of the alternative embodiment.
DETAILED DESCRIPTION
[0029] Embodiments of the present invention are drawn to methods
and flow batteries that improve/optimize the electrolyte pathway
configuration in a metal-halogen flow battery.
[0030] The improved electrolyte pathway configuration improves the
metal plating morphology, reduces the corrosion rate on the metal,
and increases the voltaic efficiency. The improved electrolyte
pathway configuration also improves the coulombic efficiency of the
entire battery system.
[0031] The following documents, the disclosures of which are
incorporated herein by reference in their entirety for a teaching
of flow battery systems, can be useful for understanding and
practicing the embodiments described herein: U.S. patent
application Ser. No. 12/523,146, which is a U.S. National Phase
entry of PCT application no. PCT/US2008/051111 filed Jan. 11 2008,
which claims benefit of priority to U.S. patent application Ser.
No. 11/654,380 filed Jan. 16, 2007.
[0032] The embodiments disclosed herein relate to an
electrochemical system (also sometimes referred to as a "flow
battery"). The electrochemical system can utilize a metal-halide
electrolyte and a halogen reactant, such as molecular chlorine. The
halide in the metal-halide electrolyte and the halogen reactant can
be of the same type. For example, when the halogen reactant is
molecular chlorine, the metal halide electrolyte can contain at
least one metal chloride.
[0033] The electrochemical system can include a sealed vessel
containing an electrochemical cell in its inner volume, a
metal-halide electrolyte and a halogen reactant, and a flow circuit
configured to deliver the metal-halide electrolyte and the halogen
reactant to the electrochemical cell. The sealed vessel can be a
pressure vessel that contains the electrochemical cell. The halogen
reactant can be, for example, a molecular chlorine reactant.
[0034] In many embodiments, the halogen reactant may be used in a
liquefied form. The sealed vessel is such that it can maintain an
inside pressure above a liquefaction pressure for the halogen
reactant at a given ambient temperature. A liquefaction pressure
for a particular halogen reactant for a given temperature may be
determined from a phase diagram for the halogen reactant. The
system that utilizes the liquefied halogen reactant in the sealed
container does not require a compressor, while compressors are
often used in other electrochemical systems for compression of
gaseous halogen reactants. The system that utilizes the liquefied
halogen reactant does not require a separate storage for the
halogen reactant, which can be located outside the inner volume of
the sealed vessel. The term "liquefied halogen reactant" refers to
at least one of molecular halogen dissolved in water, which is also
known as wet halogen or aqueous halogen, and "dry" liquid molecular
halogen, which is not dissolved in water. Similarly, the term
"liquefied chlorine" may refer to at least one of molecular
chlorine dissolved in water, which is also known as wet chlorine or
aqueous chlorine, and "dry" liquid chlorine, which is not dissolved
in water.
[0035] In many embodiments, the system utilizes liquefied molecular
chlorine as a halogen reactant. The liquefied molecular chlorine
has a density which is approximately one and a half times greater
than that of water.
[0036] The flow circuit contained in the sealed container may be a
closed loop circuit that is configured to deliver the halogen
reactant, preferably in the liquefied or liquid state, and the at
least one electrolyte to and from the cell(s). In many embodiments,
the loop circuit may be a sealed loop circuit. Although the
components, such as the halogen reactant and the metal halide
electrolyte, circulated through the closed loop are preferably in a
liquefied state, the closed loop may contain therein some amount of
gas, such as chlorine gas.
[0037] Preferably, the loop circuit is such that the metal halide
electrolyte and the halogen reactant circulate through the same
flow path without a separation in the cell(s).
[0038] Each of the electrochemical cell(s) may comprise a first
electrode, which may serve as a positive electrode in a normal
discharge mode, and a second electrode, which may serve as a
negative electrode in a normal discharge mode, and a reaction zone
between the electrodes.
[0039] In many embodiments, the reaction zone may be such that no
separation of the halogen reactant, such as the halogen reactant or
ionized halogen reactant dissolved in water of the electrolyte
solution, occurs in the reaction zone. For example, when the
halogen reactant is a liquefied chlorine reactant, the reaction
zone can be such that no separation of the chlorine reactant, such
as the chlorine reactant or chlorine ions dissolved in water of the
electrolyte solution, occurs in the reaction zone. The reaction
zone may be such that it does not contain a membrane or a separator
between the positive and negative electrodes of the same cell that
is impermeable to the halogen reactant, such as the halogen
reactant or ionized halogen reactant dissolved in water of the
electrolyte solution. For example, the reaction zone may be such
that it does not contain a membrane or a separator between the
positive and negative electrodes of the same cell that is
impermeable to the liquefied chlorine reactant, such as the
chlorine reactant or chlorine ions dissolved in water of the
electrolyte solution.
[0040] In many embodiments, the reaction zone may be such that no
separation of halogen ions, such as halogen ions formed by
oxidizing the halogen reactant at one of the electrodes, from the
rest of the flow occurs in the reaction zone. In other words, the
reaction zone may be such that it does not contain a membrane or a
separator between the positive and negative electrodes of the same
cell that is impermeable for the halogen ions, such as chlorine
ions. Furthermore, the cell may be a hybrid flow battery cell
rather than a redox flow battery cell. Thus, in the hybrid flow
battery cell, a metal, such as zinc is plated onto one of the
electrodes, the reaction zone lacks an ion exchange membrane which
allows ions to pass through it (i.e., there is no ion exchange
membrane between the cathode and anode electrodes) and the
electrolyte is not separated into a catholyte and anolyte by the
ion exchange membrane.
[0041] In certain embodiments, the first electrode may be a porous
electrode or contain at least one porous element. For example, the
first electrode may comprise a porous or a permeable carbon, metal
or metal oxide electrode. For example, the first electrode may
comprise porous carbon foam, a metal mesh or a porous mixed metal
oxide coated electrode, such as a porous titanium electrode coated
with ruthenium oxide (i.e., ruthenized titanium). In a discharge
and charge modes, the first electrode may serve as a positive
electrode, at which the halogen may be reduced into halogen ions.
The use of the porous material in the first electrode may increase
efficiency of the halogen reactant's reduction and hence the
voltaic efficiency of the battery.
[0042] In many embodiments, the second electrode may comprise a
primary depositable and oxidizable metal, i.e., a metal that may be
oxidized to form cations during the discharge mode. In many
embodiments, the second electrode may comprise a metal that is of
the same type as a metal ion in one of the components of the metal
halide electrolyte. For example, when the metal halide electrolyte
comprises zinc halide, such as zinc chloride, the second electrode
may comprise metallic zinc. Alternatively, the electrode may
comprise another material, such as titanium that is plated with
zinc. In such a case, the electrochemical system may function as a
reversible system.
[0043] Thus, in some embodiments, the electrochemical system may be
reversible, i.e. capable of working in both charge and discharge
operation mode; or non-reversible, i.e. capable of working only in
a discharge operation mode. The reversible electrochemical system
usually utilizes at least one metal halide in the electrolyte, such
that the metal of the metal halide is sufficiently strong and
stable in its reduced form to be able to form an electrode. The
metal halides that can be used in the reversible system include
zinc halides, as element zinc is sufficiently stable to be able to
form an electrode. On the other hand, the non-reversible
electrochemical system does not utilize the metal halides that
satisfy the above requirements. Metals of metal halides that are
used in the non-reversible systems are usually unstable and strong
in their reduced, elemental form to be able to form an electrode.
Examples of such unstable metals and their corresponding metal
halides include potassium (K) and potassium halides and sodium (Na)
and sodium halides.
[0044] The metal halide electrolyte can be an aqueous electrolytic
solution. The electrolyte may be an aqueous solution of at least
one metal halide electrolyte compound, such as ZnCl.sub.2. For
example, the solution may be a 15-50% aqueous solution of
ZnCl.sub.2, such as a 25% solution of ZnCl.sub.2. In certain
embodiments, the electrolyte may contain one or more additives,
which can enhance the electrical conductivity of the electrolytic
solution. For example, when the electrolyte contains ZnCl.sub.2,
such additive can be one or more salts of sodium or potassium, such
as NaCl or KCl.
[0045] FIG. 1 illustrates an electrochemical system 100 which
includes at least one electrochemical cell, an electrolyte and a
halogen reactant contained in a sealed container 101. The sealed
container 101 is preferably a pressure containment vessel, which is
configured to maintain a pressure above one atmospheric pressure in
its inner volume 102. Preferably, the sealed container 101 is
configured to maintain a pressure in its inner volume above the
liquefaction pressure for the halogen reactant, such as elemental
chlorine. For functioning at a normal temperature such as
10-40.degree. C., the sealed container may be configured to
maintain an inside pressure of at least 75 psi or of at least 100
psi or of at least 125 psi or of at least 150 psi or of at least
175 psi or of at least 200 psi or of at least 250 psi or of at
least 300 psi or of at least 350 psi or of at least 400 psi or of
at least 450 psi or of at least 500 psi or of at least 550 psi or
of at least 600 psi, such as 75-650 psi or 75-400 psi and all
subranges described previously. The walls of the sealed container
may be composed of a structural material capable to withstand the
required pressure. One non-limiting example of such a material is
stainless steel.
[0046] The at least one electrochemical cell contained inside the
sealed container 101 is preferably a horizontally positioned cell,
which may include a horizontal positive electrode and horizontal
negative electrode separated by a gap. The horizontally positioned
cell may be advantageous because when the circulation of the liquid
stops due to, for example, turning off a discharge or a charge
pump, some amount of liquid (the electrolyte and /or the halogen
reactant) may remain in the reaction zone of the cell. The amount
of the liquid may be such that it provides electrical contact
between the positive and negative electrodes of the same cell. The
presence of the liquid in the reaction zone may allow a faster
restart of the electrochemical system when the circulation of the
metal halide electrolyte and the halogen reagent is restored
compared to systems that utilize a vertically positioned cell(s),
while providing for shunt interruption. The presence of the
electrolyte in the reaction zone may allow for the cell to hold a
charge in the absence of the circulation and thus, ensure that the
system provides uninterrupted power supply (UPS). The horizontally
positioned cell(s) in a combination with a liquefied chlorine
reactant used as a halogen reactant may also prevent or reduce a
formation of chlorine bubbles during the operation.
[0047] In many embodiments, the sealed container may contain more
than one electrochemical cell. In certain embodiments, the sealed
container may contain a plurality of electrochemical cells, which
may be connected in series. In some embodiments, the plurality of
electrochemical cells that are connected in series may be arranged
in a stack. For example, element 103 in FIG. 1 represents a
vertical stack of horizontally positioned electrochemical cells,
which are connected in series. The stack of horizontally positioned
cells may be similar to the one disclosed on pages 7-11 and FIGS.
1-3 of WO2008/089205, which is incorporated herein by reference in
its entirety. The advantages of a single horizontally positioned
cell apply to the stack as well.
[0048] The electrochemical system can include a feed pipe or
manifold that may be configured in a normal discharge operation
mode to deliver a mixture comprising the metal-halide electrolyte
and the liquefied halogen reactant to the at least one cell. The
electrochemical system may also include a return pipe or manifold
that may be configured in the discharge mode to collect products of
an electrochemical reaction from the at least one electrochemical
cell. Such products may be a mixture comprising the metal-halide
electrolyte and/or the liquefied halogen reactant, although the
concentration of the halogen reactant in the mixture may be reduced
compared to the mixture entering the cell due to the consumption of
the halogen reactant in the discharge mode.
[0049] For example, in FIG. 1 a feed pipe or manifold 115 is
configured to deliver a mixture comprising the metal-halide
electrolyte and the liquefied halogen reactant to the horizontally
positioned cells of the stack 103. A return pipe or manifold 120 is
configured to collect products of an electrochemical reaction from
cells of the stack. As will be further discussed, in some
embodiments, the feed pipe or manifold and/or the return pipe or
manifold may be a part of a stack assembly for the stack of the
horizontally positioned cells. In some embodiments, the stack 103
may be supported directly by walls of the vessel 101. Yet in some
embodiments, the stack 103 may be supported by one or more pipes,
pillars or strings connected to walls of the vessel 101 and/or
reservoir 119.
[0050] The feed pipe or manifold and the return pipe or manifold
may be connected to a reservoir 119 that may contain the liquefied,
e.g. liquid, halogen reactant and/or the metal halide reactant.
Such a reservoir may be located within the sealed container 101.
The reservoir, the feed pipe or manifold, the return pipe or
manifold and the at least one cell may form a loop circuit for
circulating the metal-halide electrolyte and the liquefied halogen
reactant.
[0051] The metal-halide electrolyte and the liquefied halogen
reactant may flow through the loop circuit in opposite directions
in charge and discharge modes. In the discharge mode, the feed pipe
or manifold 115 may be used for delivering the metal-halide
electrolyte and the liquefied halogen reactant to the at least one
cell 103 from the reservoir 119 and the return pipe or manifold 120
for delivering the metal-halide electrolyte and the liquefied
halogen reactant from the at least one cell back to the reservoir.
In the charge mode, the return pipe or manifold 120 may be used for
delivering the metal-halide electrolyte and/or the liquefied
halogen reactant to the at least one cell 103 from the reservoir
119 and the feed pipe or manifold 115 for delivering the
metal-halide electrolyte and/or the liquefied halogen reactant from
the at least one cell 103 back to the reservoir 119.
[0052] In some embodiments, when the system utilizes a vertical
stack of horizontally positioned cells, the return pipe or manifold
120 may be an upward-flowing return pipe or manifold. The pipe 120
includes an upward running section 121 and a downward running
section 122. The flow of the metal-halide electrolyte and the
liquefied halogen electrolyte leaves the cells of the stack 103 in
the discharge mode upward through the section 121 and then goes
downward to the reservoir through the section 122. The upward
flowing return pipe or manifold may prevent the flow from going
mostly through the bottom cell of the stack 103, thereby, providing
a more uniform flow path resistance between the cells of the
stack.
[0053] The electrochemical system may include one or more pumps for
pumping the metal-halide electrolyte and the liquefied halogen
reactant. Such a pump may or may not be located within the inner
volume of the sealed vessel. For example, FIG. 1 shows discharge
pump 123, which fluidly connects the reservoir 119 and the feed
pipe or manifold 115 and which is configured to deliver the
metal-halide electrolyte and the liquefied halogen reactant through
the feed pipe or manifold 115 to the electrochemical cell(s) 103 in
the discharge mode. In some embodiments, the electrochemical system
may include charge pump depicted as element 124 in FIG. 1. The
charge pump fluidly connects the return pipe or manifold 120 to the
reservoir 119 and can be used to deliver the metal-halide
electrolyte and the liquefied halogen reactant through the return
pipe or manifold to the electrochemical cell(s) in the charge mode.
In some embodiments, the electrochemical system may include both
charge and discharge pumps. The charge and discharge pumps may be
configured to pump the metal-halide electrolyte and the liquefied
halogen reactant in the opposite directions through the loop
circuit that includes the feed pipe or manifold and the return pump
or manifold. Preferably, the charge and discharge pumps are
configured in such a way so that only one pump operates at a given
time. Such an arrangement may improve the reliability of the system
and increase the lifetime of the system. The opposite pump
arrangement may also allow one not to use in the system a valve for
switching between the charge and discharge modes. Such a switch
valve may often cost more than an additional pump. Thus, the
opposite pump arrangement may reduce the overall cost of the
system.
[0054] Pumps that are used in the system may be centripetal pumps.
In some embodiments, it may be preferred to use a pump that is
capable to provide a pumping rate of at least 30 L/min
[0055] FIG. 1 depicts the reservoir as element 119. The reservoir
119 may be made of a material that is inert to the halogen
reactant. One non-limiting example of such an inert material may be
a polymer material, such as polyvinyl chloride (PVC). The reservoir
119 may also store the metal halide electrolyte. In such a case, if
the liquefied chlorine is used as a liquefied halogen reactant,
then the chlorine can be separated from the metal halide
electrolyte due to a higher density (specific gravity) of the
former, and/or by a separation device as described in copending
U.S. Patent Application Ser. No. 61/364631, the disclosure of which
is hereby incorporated by reference in its entirety for a teaching
of the separation device. FIG. 1 shows liquefied chlorine at the
lower part of the reservoir (element 126) and the metal-halide
electrolyte being above the liquefied chlorine in the reservoir
(element 125).
[0056] The reservoir 119 may contain a feed line for the liquefied
halogen reactant, which may supply the halogen reactant to the feed
pipe or manifold 115 of the system. A connection between the
halogen reactant feed line and the feed manifold of the system may
occur before, at or after a discharge pump 123. In some
embodiments, the connection between the halogen reactant feed line
and the feed manifold of the system may comprise a mixing venturi.
FIG. 1 presents the feed line for the liquefied halogen reactant as
element 127. An inlet of the feed line 127, such as a pipe or
conduit, may extend to the lower part 126 of the reservoir 119,
where the liquefied halogen reactant, such as the liquefied
chlorine reactant, may be stored. An outlet of the feed line 127 is
connected to an inlet of the discharge pump 123. The electrolyte
intake feed line, such as a pipe or conduit 132, may extend to the
upper part 125, where the metal-halide electrolyte is located.
[0057] As noted above, in some embodiments, the reservoir 119 may
include a separation device, such as one or more sump plates, which
may be, for example, a horizontal plate with holes in it. The sump
plate may facilitate the settling down of the liquefied halogen
reactant, such as liquefied chlorine reactant, at the lower part
126 of the reservoir, when the liquefied halogen reactant returns
to the reservoir 119, for example, from the return pipe or manifold
120 in the discharge mode. The reservoir 119 is preferably but not
necessarily located below the stack of cells 103.
[0058] In some embodiments, the reservoir 119 may include one or
more baffle plates. Such baffle plates may be vertical plates
located at the top and bottom of the reservoir. The baffle plates
may reduce and/or prevent eddy currents in the returning flow of
the metal-halide electrolyte and the liquefied halogen reactant,
thereby enhancing the separation of the liquefied halogen from the
metal-halide electrolyte in the reservoir.
[0059] In certain embodiments, the discharge pump may be positioned
with respect to the reservoir so that its inlet/outlet is located
below the upper level of the metal-halide electrolyte in the
reservoir. In certain embodiments, the inlet/outlet of the
discharge pump may be positioned horizontally or essentially
horizontally. In such an arrangement, the flow of the metal-halide
electrolyte and the liquefied halogen reactant may make a 90 degree
turn in the discharge pump from a horizontal direction in the inlet
to a vertical direction in the feed manifold or pipe 115. In some
embodiments, the inlet of the discharge pump 123 may include a
bellmouth piece, which may slow down the flow and thereby
prevent/reduce formation of turbulence in the reservoir.
[0060] The charge pump may also be positioned with its inlet/outlet
located below the upper level of the metal-halide electrolyte in
the reservoir. In certain embodiments, the inlet/outlet of the
charge pump may be located at a lower level than the inlet/outlet
of the discharge pump. The inlet/outlet of the charge pump may also
have a bellmouth piece, which may slow down the flow and thereby
prevent/reduce formation of turbulence in the reservoir.
[0061] Thus, in summary, the reservoir 119 which has a lower part
126, which may contain the liquefied halogen reactant, such as a
liquefied molecular chlorine reactant; an upper part 125, which may
contain the metal halide reactant; a horizontal sump plate,
vertical baffle plates, a horizontal inlet of a discharge pump, a
horizontal outlet of a charge pump and a feed line for the
liquefied halogen reactant, which has an inlet in the lower part
126 of the reservoir and which is connected to the discharge pump's
inlet. The sump plate is positioned approximately at the level
where the boundary between the metal-halide electrolyte and the
halogen reactant is expected to be located. Discharge pump's inlet
and charge pump's outlet may protrude through the walls of the
reservoir.
[0062] In some embodiments, the electrochemical system may include
a controlling element, which may be used, for example, for
controlling a rate of the discharge pump, a rate of the charge pump
and/or a rate of feeding the halogen reactant into the electrolyte.
Such a controlling element may be an analog circuit. FIG. 1 depicts
the controlling element as element 128, which may control one or
more of the following parameters: rates of the charge pump 124 and
the discharge pump 123 and a feed rate of the liquefied chlorine
reactant through the feed line 127.
[0063] The inner volume of the sealed container may have several
pressurized zones, each having a different pressure. For example,
the inner volume may include a first zone, and a second zone having
a pressure higher than that of the first zone. In some embodiments,
the first zone may be enveloped or surrounded by the second, higher
pressure zone. The first zone may contain the electrolyte
/liquefied halogen reactant loop, i.e. the reservoir 119, the
cell(s) 103, pump(s) 123 and 124, manifold(s) 115, 120, while the
second surrounding or enveloping zone may be a space between the
first zone and the walls of the sealed vessel 101. In FIG. 1, the
cells 103, the feed manifold or pipe 115, the reservoir 119,
including the metal halide reactant in the upper part 125 of the
reservoir and the liquefied halogen reactant in its lower part 126,
and the return manifold or pipe 120 all may be in the first
pressure zone, while the higher pressure second zone may be
represented by the areas 129, 130 and 131 of the inner volume of
the vessel 101.
[0064] In such an arrangement, a pressure in the first zone may be
a pressure sufficient to liquefy the halogen reactant at a given
temperature. Such a pressure may be at least 75 psi or at least 100
psi or at least 125 psi or at least 150 psi or at least 175 psi or
at least 200 psi or at least 250 psi or at least 300 psi or at
least 350 psi or at least 400 psi, such as 75-450 psi or 75-400 psi
and all subranges in between. At the same time, a surrounding
pressure in the second pressure zone may be higher than a maximum
operating pressure of the first zone. Such a surrounding pressure
may be at least 75 psi or at least 100 psi or at least 125 psi or
at least 150 psi or at least 175 psi or at least 200 psi or at
least 250 psi or at least 300 psi or at least 350 psi or at least
400 psi or at least 450 psi or at least 500 psi or at least 550 psi
or at least 600 psi, such as 75-650 psi or 200-650 psi or 400-650
psi and all the subranges in between.
[0065] The enveloped arrangement may provide a number of
advantages. For example, in the event of a leak from the first
zone/loop circuit, the higher pressure in the surrounding second
zone may cause the leaking component(s) to flow inwards the first
zone, instead of outwards. Also, the surrounding higher pressure
zone may reduce/prevent fatigue crack propagation over components
of the first zone/loop circuit, including components made of
plastic, such as manifolds and walls of reservoir. The pressurized
envelope arrangement may also allow using thinner outer wall(s) for
the sealed container/vessel, which can, nevertheless, prevent
deformation(s) that could negatively impact internal flow
geometries for the metal-halide electrolyte and the liquefied
halogen reactant. In the absence of the pressurizing second zone,
thicker outer wall(s) may be required to prevent such
deformation(s) due to an unsupported structure against expansive
force of the internal higher pressure.
[0066] In certain embodiments, the outer walls of the sealed
container/vessel may be formed by a cylindrical component and two
circular end plates, one of which may be placed on the top of the
cylindrical component and the other on the bottom in order to seal
the vessel. The use of the pressurized envelope arrangement for
such outer walls allows using thinner end plates, without exposing
internal flow geometries for the metal-halide electrolyte and the
liquefied halogen reactant compared to the case when the outer
walls are exposed to the variable pressure generated during the
operation of the system.
[0067] The second pressure zone may be filled with an inert gas,
such as argon or nitrogen. In some embodiments, the second pressure
zone may also contain an additional component that can neutralize a
reagent, such as the halogen reactant, that is leaking from the
first zone, and/or to heal walls of the first zone/ loop circuit.
Such an additional material may be, for example, a soda ash. Thus,
spaces 129, 130 and 131 may be filled with soda ash.
[0068] The electrochemical system in a pressurized envelope
arrangement may be fabricated as follows. First, a sealed loop
circuit for the metal halide electrolyte and the liquefied halogen
reagent may be fabricated. The sealed loop circuit can be such that
it is capable to maintain an inner pressure above a liquefaction
pressure of the liquefied halogen for a given temperature. The
sealed loop circuit may include one or more of the following
elements: one or more electrochemical cells, a reservoir for
storing the metal-halide electrolyte and the liquefied halogen
reactant; a feed manifold or pipe for delivering the metal-halide
electrolyte and the liquefied halogen reactant from the reservoir
to the one or more cells; a return manifold for delivering the
metal-halide electrolyte and the liquefied halogen reactant from
the one or more cells back to the reservoir; and one or more pumps.
After the loop circuit is fabricated, it may be placed inside a
vessel or container, which may be later pressurized to a pressure,
which is higher than a maximum operation pressure for a loop
circuit, and sealed. The pressurization of the vessel may be
performed by pumping in an inert gas, such as argon or nitrogen,
and optionally, one or more additional components. When the walls
of the vessel are formed by a cylindrical component and two end
plates, the sealing procedure may include the end plates at the top
and the bottom of the cylindrical component.
[0069] FIG. 2 illustrates paths for a flow of the metal-halide
electrolyte and the liquefied halogen reactant through the
horizontally positioned cells of the stack, such as the stack 103
of FIG. 1, in the discharge mode. The electrolyte flow paths in
FIG. 2 are represented by arrows. For each of the cells in the
stack, the flow may proceed from a feed pipe or manifold 21
(element 115 in FIG. 1), into a distribution zone 22, through a
porous "chlorine" electrode 23, over a metal electrode 25, which
may comprise a substrate, which may be, for example, a titanium
substrate or a ruthenized titanium substrate, and an oxidizable
metal, which may be, for example, zinc, on the substrate, to a
collection zone 26, through an upward return manifold 27 (element
121 in FIG. 1), and to a return pipe 29 (element 122 in FIG.
1).
[0070] In some embodiments, an element 24 may be placed on a bottom
of metal electrode 25. Yet in some other embodiments, such an
element may be omitted. The purpose of the element 24 may be to
prevent the flow of the metal-halide electrolyte from contacting
the active metal electrode, when passing through a porous electrode
of an adjacent cell located beneath. In other words, element 24
prevents the electrolyte from touching one side (e.g., the bottom
side) of every metal electrode 25 so that the metal (e.g., zinc)
plates only on the opposite side (e.g., the top side) of the metal
electrode 25. In some cases, the element 24 may comprise the
polymer or plastic material.
[0071] FIG. 2 also shows barriers 30. Each barrier 30 may be a part
of a cell frame 31 discussed in a greater detail below. Barrier 30
may separate the positive electrode from the negative electrode of
the same cell. Barriers 30 may comprise an electrically insulating
material, which can be a polymeric material, such as PTFE. The cell
frames 31 can be made of a polymeric material, such as PTFE. The
cell frames 31 may comprise plate shaped frames which are stacked
on top of each other such that openings in the cell frames are
aligned to form manifolds 21, 27 and 29. However, other manifold
configurations may be used if desired.
[0072] In the configuration depicted in FIG. 2, the metal-halide
electrolyte may be forced to flow down through the porous electrode
and then up to leave the cell. Such a down-and-up flow path may
enable an electrical contact of the porous electrode and the metal
electrode in each cell with a pool of the metal halide electrolyte
remaining in each cell when the electrolyte flow stops and the feed
manifold, distribution zone, collection zone, and return manifold
drain. Such a contact may allow maintaining an electrical
continuity in the stack of cells when the flow stops and may
provide for an uninterrupted power supply (UPS) application without
continuous pump operation. The down-and-up flow path within each
cell may also interrupt shunt currents that otherwise would occur
when electrolyte flow stops. The shunt currents are not desired
because they may lead to undesirable self-discharge of the energy
stored in the system and an adverse non-uniform distribution of one
or more active materials, such as an oxidizable metal, such as Zn,
throughout the stack.
[0073] FIGS. 3A and 3B illustrate the features of charge face or
surface (e.g., bottom surface) and discharge face or surface (e.g.,
top surface), respectively, of a frame 31 for holding the
horizontally positioned electrochemical cells illustrated in FIG.
2. The frame 31 includes a charge mode inlet manifold 1 through
which electrolyte is supplied to the electrochemical cells during
charge mode. As noted above, the manifold 1 is a hole through the
frame 31 which aligns with similar holes in other stacked frames 31
to form the manifold. The manifold 1 may comprise the same manifold
as the manifolds 115, 21 shown in FIGS. 1 and 2. The electrolyte
flows from the charge mode inlet manifold 1 through flow channels
40c and inlet 61 in the frame 31 to the electrochemical cells. In
the embodiment illustrated in FIG. 3A, the charge mode inlet
manifold 1 connects to a single flow channel 40c which successively
divides into subchannels (i.e., flow splitting nodes where each
channel is split into two subchannels two or more times) to provide
a more even and laminar electrolyte flow to the electrodes 23, 25.
After passing across the electrodes 23, 25, the electrolyte exits
the cells via common exit 65 into flow channels 40e on an opposite
end or side of the frame 31 from the charge inlet manifold 1. The
electrolyte empties from the exit flow channels 40e to a common
outlet (i.e., drain) manifold 3. The outlet manifold 3 may comprise
the same manifold as manifolds 121 and 27 in FIGS. 1 and 2,
respectively. Exit channels 40e may also comprise flow splitting
nodes/subchannels as shown in FIG. 3A. As illustrated in FIG. 3A,
only the charge mode inlet manifold 1 is fluidly connected to the
channels 40c on the charge side of the frame 31.
[0074] As illustrated in FIG. 3B, on the discharge side, the
discharge mode inlet manifold 2 (not shown in FIGS. 1 and 2) is
connected to discharge inlet channels 40d while the charge inlet
manifold 1 is fluidly isolated from the discharge inlet channels
40d. The common outlet (i.e., drain) manifold 3 is connected to the
electrochemical cells via optional bypass channels 44 on the
discharge (e.g., top) surface of the frame 31. The operation of the
bypass channels 44 and bypass outlet 66 is discussed in more detail
below. Otherwise, the electrolyte flow passes from channels 40d and
inlet 62 through the porous electrode 23, flows through a reaction
zone of a cell and then exits via the common exit or outlet 65 and
then outlet channels 40e to the common outlet manifold 3.
[0075] FIG. 4 illustrates details of the portion of FIG. 3A
identified by the box labeled "A". In an embodiment, the inlet 61
from each of the charge mode flow channels 40c into the central
open space 41 which contains the electrochemical cells includes an
expansion portion 45. Portion 45 has a larger width than the
remaining channel 40c, and may have a continuously increasing width
toward the inlet 61 (i.e., triangular shape when viewed from
above). The expansion portion 45 aids in spreading the electrolyte
and thereby providing a more even and laminar flow distribution of
electrolyte across the electrodes 23, 25. In an embodiment, the
expansion portion 45 further includes bumps or pillars 46. The
bumps or pillars 46 interact with the flowing electrolyte to reduce
turbulence in the inlet flow. In this manner, a smoother, more
laminar electrolyte flow can be provided to the electrodes 23,
25.
[0076] FIG. 5 illustrates a cross section of an embodiment of a
stack of electrochemical cells in a stack of frames through the
line A'-A' in FIG. 3A. The cross section A'A' is transverse to the
flow of electrolyte in the electrochemical cell from inlet manifold
1 to outlet manifold 3. In this embodiment, the frame 31 includes
ledges 33 on which the non-porous (negative) metal electrode 25 is
seated. Additionally, the non-porous electrode 25 of a first
electrochemical cell 102a is spaced apart from and connected to the
porous (positive) electrode 23 of an adjacent electrochemical cell
102b by electrically conductive spacers 18, such as metal or carbon
spacers. An electrolyte flow path is thereby formed between the
non-porous electrode 25 of the first electrochemical cell 102a and
the porous electrode 23 of an adjacent electrochemical cell 102b.
Further, the conductive spacers divide the electrolyte flow path
into a series of flow channels 19.
[0077] In an embodiment, the electrodes 23, 25 of adjacent
electrochemical cells 102 are provided as an assembly 50. In this
embodiment, the non-porous electrode 25 of a first electrochemical
cell 102a, the conductive spacers 18 and the porous electrode 23 of
an adjacent electrochemical cell 102b are assembled as a single
unit. The individual components may be glued, bolted, clamped,
brazed, soldered or otherwise joined together. The fabrication of
an electrode assembly 50 simplifies and speeds the assembly of
stacked flow cell device. Each electrode assembly is placed into a
respective frame 31, such that one electrode (e.g., the larger
non-porous electrode 25) is supported by the ledges 33 in the frame
31, and the other electrode (e.g., the smaller porous electrode 23)
hangs in the space 41 between the ledges 33 by the spacers 18 from
the other electrode. Of course the order of the electrodes may be
reversed and the porous electrode may be supported by the ledges
33. Other electrode attachment configurations, such as bolting or
clamping to the frame, may be used. The frames 31 with the
electrodes 23, 25 are stacked upon each other to form a stack 103
of cells. As each frame is stacked, a new cell 102a is created with
a reaction zone 32 in between the bottom porous electrode 23 of an
upper frame and a top non-porous electrode 25 of an adjacent lower
frame. As seen in FIG. 5, the electrodes 23, 25 of the same cell
(e.g., 102a) do not physically or electrically contact each other
and comprise a portion of separate electrode assemblies.
[0078] FIG. 6 illustrates a cross section of a stack of
electrochemical cells through the line B'B' in FIG. 3A. This cross
section cuts across the charge inlet manifold 1 though the stack
103 of electrochemical cells 102 and the common outlet drain
manifold 3. As illustrated, the common outlet drain manifold 3 is
on the left side FIG. 6 while the charge inlet manifold 1 is on the
right side of FIG. 6. That is, FIG. 6 is the mirror image (i.e.,
180 degree rotation of the cross section) of FIG. 3A such that FIG.
6 may be advantageously used in combination with FIGS. 8-12 for
explanation of the electrolyte flows in the flow battery.
Specifically, the cross section of FIG. 6 illustrates the
configuration of the frames 31 and cells 102 for the charge flow
configuration illustrated in FIG. 8.
[0079] To achieve the flow configuration illustrated in FIG. 8
(100% flow-by flow in charge mode), the frame is provided with
flow-by channels 40c in the bottom face of the frame. The channels
40c connect the charge inlet manifold 1 to the reaction zone 32 of
each cell, such that 100% of the incoming electrolyte in charge
mode flows across the non-porous electrode 25 to deposit a layer of
zinc on top of each electrode 25 in each cell 102. None of the
incoming electrolyte is delivered from the charge inlet manifold 1
directly to the porous electrode 23 or through the porous electrode
23 into the reaction zone 32. At the opposite end of the
electrochemical cell from the charge inlet manifold 1, an outlet
flow channel 40e is provided in the bottom face of the frame 31 for
the electrolyte to reach the common outlet drain manifold 3. The
frame 31 also includes bypass channels 44 on the top face or
surface of the frame that allow electrolyte in the flow channels 19
to exit to the common outlet drain manifold 3.
[0080] FIG. 7 is a cross section of a stack of electrochemical
cells through the line C'-C' in FIG. 3B. FIG. 7 is the mirror image
(i.e., 180 degree rotation of the cross section) of FIG. 3B. This
cross section corresponds to the discharge flow configuration
illustrated in FIG. 10 (100% flow-through discharge flow). The
channels 40d connect the discharge inlet manifold 2 in the frame 31
to the flow channels 19 between the spacers 18 in each electrode
assembly 50. Electrolyte enters the cells 102 via discharge mode
inlet manifold 2 by passing through flow-though channels 40d
configured to deliver electrolyte to the top of the porous
electrodes 23 via inlet 62 and flow channels 19. Because there are
no flow-by channels 40c on the top face of the frame 31 which are
connected to the manifold 2, all of the electrolyte is provided to
the top of the porous electrode 23. Under a modest electrolyte flow
rate, all of the electrolyte flows through the porous electrode 23
to the reaction zone 32 below. The electrolyte then exits the cells
102 through outlet flow channels 40e to the common outlet drain
manifold 3. Under higher electrolyte flow rates, some of the
electrolyte may exit the flow channels 19 via the bypass outlet 66
and bypass channels 44 to the common outlet drain manifold 3
without passing through the porous electrode 23, reaction zone 32
and channels 40e. Alternatively, the cells and frames may be turned
upside down, such that the charge mode channels 40c are on top and
the discharge mode channels 40d are on the bottom of each
frame.
[0081] Thus, as shown in FIGS. 3A, 3B, 5, 6, 8 and 10, the charge
mode electrolyte inlet 61 is located in the reaction zone 32
between the first 23 and the second 25 electrodes. Inlet 61 is
connected to the channels 40c in the bottom of the frame, which are
connected to the charge mode inlet manifold 1. The discharge mode
electrolyte inlet 62 is located outside the reaction zone 32
adjacent to a surface of the first electrode 23 facing away from
the reaction zone 32. Specifically, inlet 62 is located between
channels 19 above the porous electrode 23 and the channels 40d in
the top of the frame 31 which connect to manifold 2. The common
electrolyte outlet or exit 65 is located in the reaction zone 32
between the first 23 and the second electrodes 25. The outlet 65 is
connected to channels 40e in the bottom of the frame 31 which
connect to manifold 3.
[0082] FIGS. 8-12 illustrate side cross sections of flow cell
embodiments with different flow configurations in charge and
discharge modes. The different flow conditions are generated by
having separate electrolyte charge mode inlet manifold 1 and
discharge mode inlet manifold 2 into the cells in the stack. A
common electrolyte outlet manifold 3 may be used in charge and
discharge modes. Thus, the flow battery preferably includes a
charge mode inlet manifold 1, a discharge mode inlet manifold 2
different from the charge mode inlet manifold 1 and a common charge
and discharge mode electrolyte outlet manifold 3. Preferably, the
common electrolyte outlet manifold 3 is configured to allow the
electrolyte out of the reaction zone in both the charge and the
discharge modes. In an embodiment, the inlet 61 from the channels
40c leading from the charge mode inlet manifold 1 is located in or
directly adjacent the reaction zone 32 between the first and the
second electrodes 23, 25. The inlet 62 from the channels 40d
leading from the discharge mode inlet manifold 2 is located outside
the reaction zone 32 adjacent to a surface of the first electrode
23 facing away from the reaction zone 32. The outlet or exit 65
leading to channels 40e to the common electrolyte outlet manifold 3
is located in or directly adjacent the reaction zone 32 between the
first and the second electrodes 23, 25.
[0083] Alternatively, separate outlets may be used in charge and
discharge modes if desired. FIGS. 8, 9A, 9B, 9C and 9D illustrate
different flow configurations for the charge mode. FIGS. 10, 11A
and 11B illustrate different flow configurations for the discharge
mode. FIGS. 12A, 12B and 12C illustrate flow configuration for
charge mode and discharge mode in a cell containing segmented
electrodes 23, 25.
[0084] As noted above, FIGS. 8, 9A, 9B, 9C and 9D illustrate the
electrolyte flow in charge mode. In the embodiment illustrated in
FIG. 8, the electrolyte flow is configured in a 100% "flow-by"
mode. In charge mode flow-by mode, the electrolyte flows from the
manifold 1 through the charge inlet 61 directly into the reaction
zone 32. That is, the electrolyte flows past or by the first and
second electrodes 23, 25 without passing through either electrode.
After passing through the reaction zone 32, the electrolyte exits
the flow cell 102 via exit 65 to the channels 40e and then into the
common outlet manifold 3.
[0085] In the embodiment illustrated in FIG. 9A, the majority of
the electrolyte flows in charge mode flow-by mode while a minority
of the electrolyte flows in charge mode "flow-through" mode. In
charge mode flow-through mode, the electrolyte flows through the
porous electrode 23. In this embodiment, the electrolyte is
provided in charge mode from manifold 2 via inlet 62 to the top of
the porous electrode 23 and flows down through the porous electrode
23 into the reaction zone 32 under the force of gravity. As in the
previous embodiment, the electrolyte exits the flow cell 102 via
exit 65 into channels 40e and then into the common outlet manifold
3. Alternatively, if the electrolyte is provided to the top of the
porous electrode 23 via manifold 1, then a separate opening is
added between manifold 1 and channels 40d on top of the frame
31.
[0086] The embodiment illustrated in FIG. 9B is similar to the
embodiment illustrated in FIG. 9A. However, in this embodiment, a
majority of the electrolyte is provided to the flow cell 102 in
charge mode flow-though mode during the charging cycle of the cell.
A minority of the electrolyte is provided in charge mode flow-by
mode during charge. Thus, in this embodiment, at least a portion of
the electrolyte is provided in charge mode flow-by mode.
[0087] In FIG. 9C the electrolyte is provided to the flow cell 102
from the charge mode inlet manifold 1 via flow-by channels 40c and
inlet 61 in the frame 31. A majority of the electrolyte flows
across the metal electrode 25 in charge mode flow-by mode. However,
unlike the embodiment illustrated in FIG. 8, the rate of
electrolyte flow is such that a minority of the electrolyte flows
up through the porous electrode 23 and exits via bypass 44 into
manifold 3.
[0088] The embodiment illustrated in FIG. 9D is similar to the
embodiment illustrated in FIG. 9C. However, in this embodiment, the
flow rate of the electrolyte and the relative sizes of the outlet
flow channels 40e and the bypass channels 44 are such that a
majority of the electrolyte flows up through the porous electrode
23 in charge mode and exits via bypass 44 into manifold 3. In this
embodiment, a minority of the electrolyte flows across the
non-porous electrode 25 exits via exit 65 and channels 40e.
[0089] As noted above, FIGS. 10 and 11A-11B illustrate the
electrolyte flow in discharge mode. The flow configurations in
discharge mode are similar to the flow configurations in charge
mode. During discharge mode, however, at least a portion of the
electrolyte flows though the porous electrode 23. In the embodiment
illustrated in FIG. 10, the electrolyte flows in 100% discharge
flow-through mode. That is, 100% of the electrolyte flows from the
discharge inlet manifold 2, through channels 40d and 19 and the
porous electrode 23 into the reaction zone 32. After passing
through the reaction zone 32, the electrolyte exits the flow cell
102 via exit 65 and channels 40e to the common outlet drain
manifold 3.
[0090] In the discharge mode embodiment illustrated in FIG. 11A, a
majority of the electrolyte is provided in discharge flow-though
mode (i.e., from manifold 2, through the channels 40d and 19 and
through the porous electrode 23) while a minority of the
electrolyte is provided in discharge flow-by mode (i.e., between
electrodes 23 and 25 into reaction zone 32). In the discharge mode
embodiment illustrated in FIG. 11B, a majority of the electrolyte
is provided in the discharge flow-by mode while a minority of the
electrolyte is provided in the discharge flow-through mode. In the
flow-through mode, the electrolyte may be provided via manifold 1.
Alternatively, if the electrolyte is provided via manifold 2, then
an additional opening is provided between manifold 2 and channels
40c.
[0091] In the embodiments illustrated in FIGS. 11A, 11B and 11C,
the electrodes 23, 25 are segmented. That is, rather than being
made as a single, integral component, the electrodes 23, 25
comprise a plurality of separate electrode members 23a, 23b, 25a,
25b. In this embodiment, one or more common outlet drain manifolds
3 (e.g., aligned outlet openings or holes in between the electrode
members segments) are provided between the separate electrode
members 23a, 23b, 25a, 25b. Common outlet drain manifolds 3 can be
provided in the first electrode 23, the second electrode 25 or both
electrodes 23, 25. For electrodes having a circular shape when
viewed from the top, the common outlet drain manifold 3 may be in
the middle while the electrode members comprise wedge shaped
segments arranged around the common outlet drain manifold 3.
[0092] The flow configuration illustrated in FIG. 12A is 100%
flow-by in charge mode while the flow illustrated in FIG. 12B is
100% flow-through in discharge mode. However, as in the previous
embodiments illustrated in FIGS. 9A and 9B, the charge mode flow
may be configured with partial flow-by and partial flow-through.
Further, as in the previous embodiments illustrated in FIGS. 10A
and 10B, the discharge mode flow may be configured with partial
flow-by and partial flow-through.
[0093] FIG. 12C illustrates another charge mode embodiment with
segmented electrodes 23, 25. In this embodiment, similar to the
embodiment illustrated in FIG. 9C, the electrolyte is supplied
directly to the reaction zone 32 at a relatively high flow rate. A
majority of the electrolyte flows in charge mode flow-by mode while
a portion of the electrolyte is forced up through the porous
electrode 23. In this embodiment, most of the electrolyte directly
exits the flow cell 102 via exit 65 and channels 40e to the common
outlet drain manifold 3 while some of the electrolyte passes
through bypass channels 44 to the common outlet drain manifold
3.
[0094] As discussed above, the inventors have discovered that by
providing different flow configurations in charge and discharge
modes, a flatter, smoother and denser metal electroplating can be
achieved. The different charge and discharge mode flow
configurations illustrated in FIGS. 8-9 and 10-11 can be combined
as identified by the connecting lines labeled 4, 5 and 6 between
these figures. The charge mode flow configurations illustrated in
FIGS. 9C and 9D can be combined with the discharge flow
configurations illustrated in FIGS. 10, 11A and 11B.
[0095] For example, the 100% flow-by charge mode embodiment
illustrated in FIG. 8 can be combined with the 100% flow-through
discharge mode embodiment of FIG. 10, the majority flow-through
discharge mode embodiment of FIG. 11A or the minority flow-through
discharge mode embodiment of FIG. 11B, as illustrated by arrows 4.
Thus, in an embodiment of the flow battery, the charge mode inlet
manifold 1 is configured to provide all the electrolyte into the
reaction zone 32 in charge mode flow-by mode while the discharge
mode inlet manifold 2 is configured to provide no electrolyte into
the reaction zone 32 in discharge mode flow-by mode. Alternatively,
the discharge mode inlet manifold 2 is configured to provide all or
a portion of the electrolyte into the reaction zone 32 in the
discharge mode flow-through mode and a portion of the electrolyte
into the reaction zone 32 in discharge mode flow-by mode.
[0096] Alternatively, the majority flow-by charge mode embodiment
illustrated in FIG. 9A can be combined with the 100% flow-though
discharge mode embodiment illustrated in FIG. 10 or the majority
flow-though discharge mode embodiment illustrated in FIG. 11A, as
illustrated by arrows 5. Thus, in an embodiment, the charge mode
inlet manifold 1 is configured to provide a major portion of the
electrolyte into the reaction zone 32 in the charge mode flow-by
mode and the discharge mode inlet manifold 2 is configured to
provide all of the electrolyte into the reaction zone 32 in the
discharge mode flow-through mode. Alternatively, the charge mode
inlet manifold 1 is configured to provide a major portion of the
electrolyte into the reaction zone 32 in the charge mode flow-by
mode and the discharge mode inlet manifold 2 is configured to
provide a minor portion of the electrolyte into the reaction zone
32 in the charge mode flow-by mode and the rest in discharge mode
flow-through mode.
[0097] Alternatively, the minority flow-by embodiment illustrated
in FIG. 9B may be combined with the 100% flow-through discharge
mode embodiment illustrated in FIG. 10 or the minority flow-through
discharge embodiment illustrated in FIG. 11B, as shown by arrows 6.
Thus, in an embodiment, the charge mode inlet manifold 1 is
configured to provide a minor portion of the electrolyte into the
reaction zone 32 in the charge mode flow-by mode and the discharge
mode inlet manifold 2 is configured to provide all of the
electrolyte into the reaction zone 32 in the discharge mode flow
through mode. Alternatively, the charge mode inlet manifold 1 is
configured to provide a minor portion of the electrolyte into the
reaction zone 32 in the charge mode flow-by mode and the discharge
mode inlet manifold 2 is configured to provide a minority the
electrolyte into the reaction zone 32.
[0098] The charge mode embodiments illustrated in FIGS. 9C and 9D
may be combined with any of the discharge mode embodiments
illustrated in FIGS. 10, 11A or 11B. Thus, in charge mode,
electrolyte may initially supplied charge mode flow-by mode with
subsequent portions of the electrolyte flowing up through the
porous electrode in charge mode flow-though mode while in discharge
mode the electrolyte may be supplied in 100% discharge mode
flow-through mode (FIG. 10), majority discharge mode flow-through
mode (FIG. 11A) or minority discharge mode flow-through mode (FIG.
11B).
[0099] As used above, the term "major portion" means more than 50%
of the electrolyte by volume, such as 51-99%, for example, 60-90%
by volume. The term "minor portion" means less than 50% of the
electrolyte by volume, such as 1-49%, for example, 10-40% by
volume.
[0100] The segmented electrode charge and discharge mode flow
configurations illustrated in respective FIGS. 12A, 12B and 12C may
be combined similarly as the embodiments illustrated in FIGS. 8-9
and 10-11. That is, a 100% flow-by charge mode embodiment can be
combined with a 100% flow-through discharge mode embodiment, a
majority flow-through discharge mode embodiment or a minority
flow-through discharge mode embodiment. Alternatively, a majority
flow-by charge mode embodiment can be combined with a 100%
flow-though discharge mode embodiment or a majority flow-though
discharge mode embodiment. Alternatively, a minority flow-by charge
mode embodiment may be combined with a 100% flow-through discharge
mode embodiment or a minority flow-through discharge mode
embodiment. Further, the embodiments illustrated in FIGS. 8-11 can
be combined with the embodiments illustrated in FIG. 12A, 12B and
12C. That is, one of either the first electrode 23 or the second
electrode 25 may be a single integral electrode while the other is
segmented.
[0101] In summary, as described above, the flow battery is
configured with a first electrolyte flow configuration in charge
mode and a second flow configuration in discharge mode. The first
electrolyte flow configuration is at least partially different from
the second electrolyte flow configuration. In the charge mode, at
least a portion of the electrolyte is provided from a charge mode
inlet manifold 1 into the reaction zone 32 and from the reaction
zone 32 into a common electrolyte outlet manifold 3. In the
discharge mode, at least a portion of the electrolyte is provided
from a discharge mode inlet manifold 2 into the reaction zone 32
and from the reaction zone 32 into the common electrolyte outlet
manifold 3. Thus, the flow battery may operate with a higher
voltaic and columbic efficiency than the same battery operating
with the same first and second flow configurations.
[0102] FIGS. 13A-13C illustrate an alternative embodiment of the
invention which contains two reservoirs and two outlet manifolds in
the frames. FIGS. 13A and 13B illustrate charge and discharge
sides, respectively, of a frame 31 of the alternative embodiment.
The frame shown in FIGS. 13A and 13B is similar to the frame shown
in FIGS. 3A and 3B, except that the common outlet manifold 3 is
replaced with different and separate charge mode outlet manifold 3A
and discharge mode outlet manifold 3B. While the manifolds 3A and
3B are referred to as "charge" and "discharge" mode outlet
manifolds, these designations are used for convenience only. As
will be described in more detail below, both manifolds are
preferably used in the charge mode and only the "charge" mode
outlet manifold is used in discharge mode.
[0103] As shown in FIG. 13A, the charge and discharge mode outlet
manifolds 3A and 3B may be located side by side on the opposite
side of the frame 31 from the respective charge and discharge mode
inlet manifolds 1 and 2. The inlet manifolds 1, 2, the channels
40c, 40d and the inlets 61, 62 are the same in FIGS. 13A, 13B as in
respective FIGS. 3A, 3B, described above.
[0104] However, in FIG. 13A, the charge mode electrolyte outlet 65
is configured to provide the electrolyte out of the reaction zone
in both the charge mode and the discharge mode through the exit
channels 40e into the charge mode outlet manifold 3A (rather than
into a common manifold). As shown in FIG. 13B, the discharge mode
electrolyte outlet 66 is configured to provide the electrolyte out
of the reaction zone in the charge mode through discharge mode
outlet channels 44 into the discharge mode outlet manifold 3B.
Thus, in FIG. 13B, channels 44 are referred to as discharge mode
outlet channels rather than bypass channels 44 because channels 44
in FIG. 13B connect to a different outlet manifold 3B than channels
40e.
[0105] Similar to outlet 65 and channels 40e shown in FIGS. 3A, the
charge mode electrolyte outlet 65 is located in the reaction zone
between the permeable and the impermeable electrodes, and channels
40e are located in the first or "charge" side of the frame 31, as
shown in FIG. 13A. The discharge mode electrolyte outlet 66 is
located outside the reaction zone adjacent to the surface of the
first electrode facing away from the reaction zone, and channels 44
are located in the opposite second or "discharge" side of the frame
31 as shown in FIG. 13B. The plural charge mode outlet channels 40e
are connected to the charge mode outlet manifold 3A formed by one
set of aligned openings in the stack of frames, while one or more
discharge mode outlet channels 44 are connected to a discharge mode
outlet manifold 3B formed by different aligned openings in the
stack of frames.
[0106] Preferably, the configuration shown in FIGS. 13A and 13B is
used together with separate electrolyte reservoirs, as shown in
FIG. 13C. The flow battery system 1300 shown in FIG. 13C includes
the stack 103 of flow cells described above which is fluidly
connected to separate dissolved chlorine poor and dissolved
chlorine rich reservoirs 119A and 119B, respectively. To include
flow batteries that use halogen other than chlorine, reservoir 119A
may be generically referred to as "a liquefied halogen reactant
poor electrolyte reservoir" which contains a volume configured to
selectively accumulate the electrolyte (e.g., zinc chloride), while
reservoir 119B may be referred to as "a liquefied halogen reactant
rich electrolyte reservoir" which contains a volume configured to
selectively accumulate the liquefied halogen reactant (e.g., the
dissolved chlorine) in addition to the electrolyte. In other words,
reservoir 119A contains an electrolyte (e.g., zinc chloride) which
contains less liquefied halogen reactant (e.g., dissolved chlorine)
than reservoir 119B.
[0107] System 1300 also includes a charge mode pump 123 fluidly
connected to the charge mode inlet manifold 1, and a discharge mode
pump 124 connected to the discharge mode inlet manifold 2.
[0108] The charge mode inlet manifold 1 and the charge mode outlet
manifold 3A are in fluid communication with the liquefied halogen
reactant poor electrolyte reservoir 119A but not with the liquefied
halogen reactant rich electrolyte reservoir 119B. For example, the
charge mode feed line 133 extends into the reservoir 119A and
connects to manifold 1, while the outlet from manifold 3A outlets
into the reservoir 119A.
[0109] The discharge mode inlet manifold 2 and the discharge mode
outlet manifold 3B are in fluid communication with the liquefied
halogen reactant rich electrolyte reservoir 119B but not with the
liquefied halogen reactant poor electrolyte reservoir 119A. For
example, the discharge mode feed line(s) 132/127 extend(s) into the
reservoir 119B and connect to manifold 2, while the outlet from
manifold 3B outlets into the reservoir 119B.
[0110] The flow battery system 1300 operates as follows with
reference to FIG. 13C. In the charge mode, the electrolyte is
provided from a charge mode electrolyte inlet 61 into the reaction
zone 32 of each flow cell (see FIG. 5), and from the reaction zone
32 into both a charge mode electrolyte outlet 65 and into a
discharge mode electrolyte outlet 66 illustrated in FIGS. 13A and
13B, respectively. Preferably, all of the electrolyte, such as the
dissolved chlorine poor zinc chloride electrolyte used in the flow
cells during the charge mode operation is provided using the charge
mode pump 123 from the liquefied halogen reactant poor electrolyte
reservoir 119A through the charge mode inlet conduit 1, the charge
mode inlet channels 40c, and the charge mode electrolyte inlet 61
into the reaction zone 32. The electrolyte is then provided from
the reaction zone through the charge mode electrolyte outlet 65,
the charge mode outlet channels 40e and the charge mode outlet
conduit 3A into the liquefied halogen reactant poor electrolyte
reservoir 119A, and through the permeable electrode 23, the
discharge mode electrolyte outlet 66, the channels 44 and the
discharge mode outlet conduit 3B into the liquefied halogen
reactant rich electrolyte reservoir 119B.
[0111] In the discharge mode, the electrolyte is provided from the
discharge mode electrolyte inlet 62 into the reaction zone 32, and
from the reaction zone 32 into the charge mode electrolyte outlet
65. Preferably, a dissolved chlorine rich zinc chloride electrolyte
is used in the flow cells during the discharge mode operation. This
electrolyte is provided from reservoir 119B and this electrolyte
has more dissolved chlorine (e.g., 2 to 10 times more dissolved
chlorine) than the dissolved chlorine poor zinc chloride
electrolyte provided from reservoir 119A during charge mode. Thus,
the dissolved chlorine poor reservoir 119A may be referred to as a
"charge mode reservoir" and the dissolved chlorine rich reservoir
119B may be referred to as the "discharge mode reservoir".
[0112] Preferably, all electrolyte (e.g., the dissolved chlorine
rich electrolyte) used in the flow cells during discharge mode
operation is provided using a discharge mode pump 124 from the
liquefied halogen reactant rich electrolyte reservoir 119B through
the discharge mode inlet conduit 2, the discharge mode inlet
channels 40d, the discharge mode electrolyte inlet 62 and through
the porous electrode 23 into the reaction zone 32. The electrolyte
is then provided from the reaction zone 32 through the charge mode
electrolyte outlet 65, outlet channels 40e and the charge mode
outlet conduit 3A into the liquefied halogen reactant poor
electrolyte reservoir 119A.
[0113] Thus, in charge mode, all electrolyte (i.e., the chlorine
poor electrolyte) comes into the stack 103 from reservoir 119A via
manifold 1, but leaves the stack 103 through both outlet manifolds
3A and 3B into respective reservoirs 119A and 119B. The electrolyte
is separated on exiting the stack such that the dissolved chlorine
poor portion is provided into reservoir 119A from the reaction zone
via outlet 65 and manifold 3A, while the dissolved chlorine rich
portion is provided into reservoir 119B through the permeable
electrode 23 via outlet 66 and manifold 3B. In contrast, in
discharge mode, all of the electrolyte (e.g., the dissolved
chlorine rich electrolyte) comes into the stack 103 from reservoir
119B via manifold 2 and leaves the stack 103 (as dissolved chlorine
poor electrolyte) only through outlet manifold 3A into its
respective reservoir 119A. The discharge outlet manifold 3B may be
closed off from the stack 103 in discharge mode by closing valve 67
in manifold 3B. Valve 67 may be open during the charge mode.
Therefore, as noted above, the terms "charge" and "discharge" with
respect to manifolds, channels and inlets in this embodiment are
provided for convenience only, because the discharge flows cross
over in charge and discharge mode.
[0114] In summary, with reference to FIG. 13C, in charge mode, the
charge inlet manifold 1 draws electrolyte from reservoir or tank
119A. The electrolyte enters the cell in stack 103 via inlet 61 and
is channeled using flow configurations shown in FIGS. 9C or 9D. The
chlorine poor portion of the electrolyte flowing between the two
electrodes 23, 25 in a flow cell reaction zone 32 exits the cell
via outlet 65 and is routed towards the charge outlet manifold 3A.
The electrolyte flowing via the charge outlet manifold 3A is low in
dissolved Cl.sub.2 and directed to tank 119A. The chlorine rich
electrolyte flowing through the porous electrode 23 as shown in
FIGS. 9C or 9D exits the cell via outlet 66 and routed towards the
discharge outlet manifold 3B. The electrolyte flowing via the
discharge outlet manifold 3B is rich in dissolved Cl.sub.2 and is
directed to reservoir or tank 119B.
[0115] In discharge mode, the discharge inlet manifold 2 draws the
dissolved Cl.sub.2 rich electrolyte from tank 119B. This
electrolyte enters the cell in stack 103 via inlet 62 and is
channeled using the flow configuration shown in FIG. 10. The
electrolyte exits via outlet 65 and routed towards the charge
outlet manifold 3A. The electrolyte exiting the stack via the
charge outlet manifold 3A is low in dissolved Cl.sub.2 and is
directed to tank 119A.
[0116] Therefore, with reference to FIGS. 9C, 9D and 13A, the
charge mode electrolyte inlet 61 is configured to provide all of
the electrolyte into the reaction zone 32 in the charge mode and
the discharge mode electrolyte inlet 62 is configured to provide no
electrolyte into the reaction zone in the charge mode. The
discharge mode electrolyte inlet 62 is configured to provide all of
the electrolyte into the reaction zone 32 in the discharge mode and
the charge mode electrolyte inlet 61 is configured to provide no
electrolyte into the reaction zone in the discharge mode, as shown
in FIGS. 10 and 13A.
[0117] The charge mode electrolyte outlet 65 is configured to
provide the liquefied halogen reactant poor portion of the
electrolyte out of the reaction zone 32 to the liquefied halogen
reactant poor electrolyte reservoir 119A in the charge mode, as
shown in FIGS. 9C, 9D and 13A. The discharge mode electrolyte
outlet 66 is configured to provide a liquefied halogen reactant
rich portion of the electrolyte from the reaction zone to the
liquefied halogen reactant rich electrolyte reservoir 119B in the
charge mode (e.g., because valve 67 is open), as shown in FIGS. 9C,
9D and 13A
[0118] The discharge mode electrolyte outlet 66 is configured to
provide no electrolyte from the reaction zone 32 in the discharge
mode (e.g., because the valve 67 is closed) and the charge mode
electrolyte outlet 65 is configured to provide all of the
electrolyte which comprises a liquefied halogen reactant poor
electrolyte from the reaction zone 32 to the liquefied halogen
reactant poor electrolyte reservoir 119A in the discharge mode.
[0119] Although the foregoing refers to particular preferred
embodiments, it will be understood that the invention is not so
limited. It will occur to those of ordinary skill in the art that
various modifications may be made to the disclosed embodiments and
that such modifications are intended to be within the scope of the
invention. All of the publications, patent applications and patents
cited herein are incorporated herein by reference in their
entirety.
* * * * *