Patent Description:
Of electrochemical batteries, a metal air battery and a fuel cell have a common feature in that air including oxygen is supplied to a cathode. For example, the metal air battery includes a plurality of metal air cells, and each of the metal air cells includes an anode capable of intercalating and deintercalating ions and a cathode using oxygen in air as an active material. A reduction/oxidation reaction of oxygen introduced from the outside occurs at the cathode, and an oxidation/reduction reaction of a metal occurs at the anode. The metal air battery changes chemical energy generated when the oxidation/reduction reaction occurs into electrical energy and outputs the electrical energy. The metal air battery absorbs oxygen during discharging and emits oxygen during charging.

In addition, the fuel cell is a device that directly changes chemical energy of a fuel into electrical energy through an electrochemical reaction and is a kind of a power generation device that is capable of continuously generating electricity so long as a fuel is supplied thereto. In the fuel cell, when air including oxygen is supplied to a cathode, and a fuel such as methanol or hydrogen is supplied to an anode, an electrochemical reaction occurs through an electrolyte film between the cathode and the anode, thereby generating electricity.

To provide improved performance, improved configurations of the electrochemical battery are needed.

<CIT> relates to a metal-air battery featuring continuous air recirculation.

<CIT> relates to a vehicular metal-air battery system providing oxygen to the vehicle's cabin.

<CIT> relates to a vehicular metal-air battery system providing storage for oxygen generated during charge.

The invention provides an electrochemical battery according to claims <NUM> and <NUM>, and a method for operating an electrochemical battery according to claims <NUM> and <NUM>. Optional features of the invention are set out in the dependent claims.

Hereinafter, an electrochemical battery maintaining an oxygen concentration by air recirculation will be described in detail with reference to the accompanying drawings, wherein like reference numerals refer to like elements throughout. In the drawings, the dimensions of elements are exaggerated for clarity of the inventive concept. The following embodiments are merely examples, and various modifications may be made thereto. It will be understood that when an element is referred to as being "on," "connected to" or "coupled to" another element, it may be directly on, connected or coupled to the other element, or intervening elements may be present.

Thus, "a first element," "component," "region," "layer," or "section" discussed below could be termed a second element, component, region, layer, or section without departing from the teachings herein.

As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms, including "at least one," unless the content clearly indicates otherwise.

The exemplary term "lower," can therefore, encompasses both an orientation of "lower" and "upper," depending on the particular orientation of the figure. The exemplary terms "below" or "beneath" can, therefore, encompass both an orientation of above and below.

For example, "about" can mean within one or more standard deviations, or within ± <NUM>%, <NUM>%, <NUM>%, or <NUM>% of the stated value.

Gas concentrations are in volume percent. For example, an oxygen concentration of <NUM>% refers to an oxygen concentration of <NUM>% by volume.

<FIG> is a schematic block diagram of an electrochemical battery <NUM> according to an embodiment. Referring to <FIG>, the electrochemical battery <NUM> according to the present embodiment may include a battery module <NUM> including an electrochemical cell, an air supplier <NUM> configured to supply air to the battery module <NUM>, an air recirculator <NUM> configured to recirculate air exhausted from the battery module <NUM>, and a controller <NUM> configured to control operation of the air supplier <NUM> and the air recirculator <NUM>. In an embodiment, the controller is configured to maintain a constant oxygen concentration in the air supplied to the battery module <NUM>. The controller may be configured to operate intermittently or continuously. In addition, the electrochemical battery <NUM> may further include an oxygen sensor <NUM> configured to measure an oxygen concentration. The oxygen sensor <NUM> may be disposed to measure at least one selected from an oxygen concentration in air supplied to the battery module <NUM>, an oxygen concentration in the battery module <NUM>, and an oxygen concentration in air exhausted from the battery module <NUM>.

The battery module <NUM> may include at least one metal air cell using oxygen in air as a cathode active material or at least one fuel cell which is configured to convert chemical energy of a fuel into electrical energy through an electrochemical reaction. For example, in an embodiment where the battery module <NUM> comprises at least one metal air cell, each metal air cell in the battery module <NUM> may generate electricity by using an oxidation of a metal and a reduction of oxygen. For example, when a metal of the metal air cell is lithium (Li), the metal air cell may generate electricity through a reaction in which lithium (Li) reacts with oxygen to generate lithium oxide (Li<NUM>O<NUM>) during discharge. On charge, lithium (Li) may be reduced from lithium oxide and oxygen may be generated. Besides lithium (Li), various other metals such as sodium, zinc, potassium, calcium, magnesium, iron, or aluminum may be used, and a reaction principal thereof may be substantially the same as lithium (Li). For example, the battery module <NUM> may include at least one selected from a sodium (Na) air cell, zinc (Zn) air cell, potassium (K) air cell, calcium (Ca) air cell, magnesium (Mg) air cell, iron (Fe) air cell, and an aluminum (Al) air cell, and alloy air cell including at least one of Li, Na, Zn, K, Ca, Mg, and Fe.

In addition, in an embodiment in which the electrochemical battery cell of the battery module <NUM> is the fuel cell, each fuel cell in the battery module <NUM> may generate electricity by directly changing chemical energy generated through an oxidation of a fuel into electrical energy. For example, when air including oxygen is supplied to a cathode, and a fuel such as methanol or hydrogen is supplied to an anode, an electrochemical reaction occurs through an electrolyte film between the cathode and the anode, thereby generating electricity.

As is further described above, since the battery module <NUM> uses oxygen during generation of electricity, it is desirable to continuously supply oxygen to the battery module <NUM>. The supply of oxygen to the battery module <NUM> may be performed by supplying air in the atmosphere to the battery module <NUM> or supplying oxygen to the battery module <NUM> from an oxygen source such as liquid oxygen. Conventionally, when air from the atmosphere is supplied to the battery module <NUM>, since an oxygen concentration in the atmosphere is only <NUM>%, in order to sufficiently supply oxygen, air in the atmosphere is usually compressed to a pressure of about <NUM> megaPascals (MPa) and is supplied to the battery module <NUM>. When the high pressure compressed air is supplied to the battery module <NUM>, a pressure in the battery module <NUM> is increased. For example, when the pressure in the battery module <NUM> is greater than about <NUM> MPa, the electrochemical cell may be mechanically abraded and damaged. In addition, since energy is consumed for compressing air, the total efficiency of the electrochemical battery <NUM> may be reduced.

The air supplier <NUM> according to the present embodiment may be configured to control the oxygen concentration in the air supplied to the battery module <NUM> and may avoid the supplying of compressed air to the battery module <NUM>. For example, after air in the atmosphere is suctioned, the air supplier <NUM> may increase the oxygen concentration in the air supplied to the battery module <NUM> by removing moisture and nitrogen from the air. In particular, the air supplier <NUM> may be configured to improve the performance of the electrochemical battery <NUM> by adjusting the oxygen concentration in the air supplied to the battery module <NUM>.

The air recirculator <NUM> may be configured to recirculate air by supplying, to the air supplier <NUM>, at least a portion of air exhausted from the battery module <NUM>. For example, the battery module <NUM> may include an air inlet port 120a through which air is introduced from the air supplier <NUM> and an air outlet port 120b through which air remaining after a reaction in the electrochemical battery cell is exhausted. The air recirculator <NUM> may include an air flow passage <NUM> configured for transferring the air exhausted through the air outlet port 120b to the air supplier <NUM>. In order to cause a sufficient reaction or a reaction under a uniform current density in the electrochemical cell, the air supplier <NUM> may supply, to the battery module <NUM>, an oxygen amount that is greater than an oxygen amount used by the electrochemical cell. Therefore, unreacted residual oxygen may be included in the air exhausted through the air outlet port 120b. The air recirculator <NUM> may reduce a load of the air supplier <NUM> by recirculating, to the battery module <NUM>, the air exhausted through the air outlet port 120b of the battery module <NUM>.

The controller <NUM> may adjust the oxygen concentration in the air supplied to the battery module <NUM> by controlling an operation of the air supplier <NUM> and the air recirculator <NUM>. For example, a feedforward control method that does not consider the state of the battery module <NUM> may be used. The oxygen concentration in the air supplied by the air supplier <NUM> may be fixed to a specific value, and the controller <NUM> may control the air supplier <NUM> such that the air supplier <NUM> supplies air having a specific oxygen concentration regardless of an actual oxygen concentration in the battery module <NUM>.

In addition, the controller <NUM> may control the operation of the air supplier <NUM> and the air recirculator <NUM> in a feedback method, based on the oxygen concentration in the air supplied to the battery module <NUM>, the oxygen concentration in the battery module <NUM>, and the oxygen concentration in the air exhausted from the battery module <NUM>. For example, the controller <NUM> may receive a measurement result from the oxygen sensor <NUM>. When the oxygen concentration in the battery module <NUM> is less than a preset concentration, the controller <NUM> may control the air supplier <NUM> to increase the oxygen concentration in the air supplied to the battery module <NUM>. In addition, when the oxygen concentration in the battery module <NUM> is greater than the preset concentration, the controller <NUM> may control the air supplier <NUM> to decrease the oxygen concentration in the air supplied to the battery module <NUM>.

Hereinafter, an oxygen concentration for improving operation of the electrochemical battery <NUM> will be further disclosed. For example, <FIG> are graphs showing a change in performance of the electrochemical battery <NUM> according to the oxygen concentration in the air supplied to the battery module <NUM> in an embodiment in which the electrochemical cell of the battery module <NUM> is the metal air cell.

<FIG> is a graph showing charging and discharging performance of the electrochemical battery <NUM> according to an oxygen concentration in an embodiment in which the electrochemical cell of the battery module <NUM> is, for example, the metal air cell. In the graph of <FIG>, lithium metal was used as an anode. A current density was maintained to about <NUM> milliampere hours per square centimeter (mAh/cm<NUM>) during discharge, and discharging was performed until a voltage dropped to about <NUM> V. In addition, an applied voltage was about <NUM> V during charge. Referring to the graph of <FIG>, until the voltage dropped to about <NUM> V, when the oxygen concentration was about <NUM>%, a discharge capacity was about <NUM> milliampere hours per gram (mAh/g). When the oxygen concentration was about <NUM>%, the discharge capacity was about <NUM> mAh/g. The discharge capacity when the oxygen concentration is about <NUM>% is greater than the discharge capacity when the oxygen concentration is about <NUM>%. The discharge capacity at an oxygen concentration of about <NUM>% was about <NUM>% of the discharge capacity when the oxygen concentration was about <NUM>%, and the discharge capacity when the oxygen concentration was about <NUM>% was not significantly different from the discharge capacity when the oxygen concentration was about <NUM>%.

<FIG> is a graph showing a charge and discharge cycle of the electrochemical battery <NUM> according to an oxygen concentration in a case where the electrochemical cell of the battery module <NUM> is, for example, the metal air cell. In the graph of <FIG>, lithium metal was used as an anode. A current density was maintained to about <NUM> mAh/cm<NUM> during discharge, and discharge was performed until a voltage dropped to about <NUM> V. In addition, an applied voltage was about <NUM> V during charge. It was shown that after charging and discharging were repeated in a state in which a discharge capacity was maintained to about <NUM> mAh/g, a charge and discharge cycle at an oxygen concentration of about <NUM>% was similar to a charge and discharge cycle at an oxygen concentration of about <NUM>%, and after charging and discharging were performed about <NUM> times, performance degradation occurred at the oxygen concentrations of about <NUM>% and about <NUM>%. The charge and discharge cycle provided the greatest capacity when the oxygen concentration was about <NUM>%.

<FIG> is a graph showing a charge and discharge cycle of the electrochemical battery <NUM> according to an oxygen concentration in in an embodiment in which the electrochemical cell of the battery module <NUM> is, for example, the metal air cell and showing the results in which charging and discharging were repeated in a state in which a discharge capacity was maintained at about <NUM> mAh/g. Until a specific capacity reached a selected level of about <NUM>% of an initial specific capacity (e.g., about <NUM> mAh/g), the cycles with the greatest capacity were when oxygen concentrations of about <NUM>% and about <NUM>% were used. When the oxygen concentration was about <NUM>%, the discharge capacity of about <NUM> mAh/g was recorded only once, and the discharge capacity was reduced from a second charge and discharge cycle. A specific capacity at oxygen concentrations of about <NUM>% and about <NUM>% reached a level of about <NUM>% of an initial specific capacity from a seventh charge and discharge cycle.

From the above-described results, when the oxygen concentration is about <NUM>%, the discharge efficiency of the electrochemical battery <NUM> may be temporarily improved, but it may be seen that as charging and discharging are repeated, degradation of the electrochemical battery <NUM> is rapidly accelerated. While not wanting to be bound by theory, this degradation is understood to occur because an electrode, an electrolyte, and the like are easily oxidized due to excess oxygen. Therefore, when <NUM>% oxygen is supplied to the electrochemical battery <NUM>, a battery life of the electrochemical battery <NUM> may be shortened. In addition, when the oxygen concentration is about <NUM>%, due to the lack of oxygen, the discharge efficiency and the cycle life of the electrochemical battery <NUM> were reduced.

As can be seen from the above, in order to improve the performance and the battery life of the electrochemical battery <NUM>, the electrochemical battery <NUM> may operate at an oxygen concentration that is greater than an oxygen concentration in the atmosphere, i.e., greater than about <NUM>%, and is less than about <NUM>%. For example, the controller <NUM> may adjust the oxygen concentration in the air supplied to the battery module <NUM> of the electrochemical battery <NUM> so to maintain an oxygen concentration in a range between a value equal to or greater than about <NUM>% and a value less than about <NUM>%. More specifically, the controller <NUM> may adjust the oxygen concentration in the air supplied to the battery module <NUM> so as to maintain in an oxygen concentration in a range between a value equal to or greater than about <NUM>% and a value less than about <NUM>% or in a range between about <NUM>% and about <NUM>%.

In <FIG>, while the embodiment where the electrochemical cell of the battery module <NUM> is the metal air cell, even when the electrochemical cell of the battery module <NUM> is a fuel cell, the oxygen concentration in the air supplied to the battery module <NUM> may be provided in an appropriate range for the fuel cell. For example, when the battery module <NUM> includes a fuel cell, an oxygen concentration of about <NUM>% to about <NUM>%, about <NUM>% to about <NUM>%, or about <NUM>% to about <NUM>% may be provided.

In order to maintain the oxygen concentration in the air supplied to the battery module <NUM> as described above, the controller <NUM> may control the operation of the air supplier <NUM> and the air recirculator <NUM>. For example, the controller <NUM> may control the air supplier <NUM> and the air recirculator <NUM> to maintain the oxygen concentration in the battery module <NUM> to a preset specific value. At this time, the controller <NUM> may compare an actual oxygen concentration measured by the oxygen sensor <NUM> with a target oxygen concentration and control the air supplier <NUM> and the air recirculator <NUM> based on a result of the comparison. For example, the controller <NUM> may control the air supplier <NUM> to adjust an air amount supplied to the battery module <NUM> and oxygen concentration in the air. The controller <NUM> may control the air recirculator <NUM> to adjust an amount of air recirculated in the air supplier <NUM> among the air exhausted through the air outlet port 120b.

<FIG> is a schematic block diagram of an air supplier <NUM> and an air recirculator <NUM> of the electrochemical battery <NUM> illustrated in <FIG>, according to an embodiment. Referring to <FIG>, the air supplier <NUM> may include an air suction device <NUM> configured to suction air from the outside, a moisture remover <NUM> configured to remove moisture from the suctioned air, and an oxygen generator <NUM> configured to generate oxygen by separating oxygen from the suctioned air. The air suction device <NUM> may be configured to adjust an air suction amount under control of the controller <NUM>. The moisture remover <NUM> is illustrated in <FIG> as being disposed in front of the oxygen generator <NUM> in an air flow direction, but a placement order may be changed between the oxygen generator <NUM> and the moisture remover <NUM>. For example, the oxygen generator <NUM> may be disposed in front of the moisture remover <NUM> in the air flow direction. In addition, the oxygen generator <NUM> and the moisture remover <NUM> may be integrated into a single assembly. Hereinafter, the embodiment where the moisture remover <NUM> is disposed in front of the oxygen generator <NUM> in the air flow direction will be further described for convenience.

The moisture remover <NUM> may be configured to remove moisture from outside air suctioned by the air suction device <NUM>. In a case where an electrochemical cell of a battery module <NUM> is a metal air cell, when moisture is present in the air, lithium hydroxide may be generated during a discharging of the electrochemical cell. Accordingly, an energy density of the electrochemical battery <NUM> may be reduced and a battery life thereof may be shortened. In this regard, the moisture remover <NUM> may be referred to as an air drier. Although not illustrated in detail, the moisture remover <NUM> may include, for example, an adsorber configured to adsorb moisture in air and a heater configured to heat the adsorber and desorb the moisture adsorbed to the adsorber. The moisture desorbed from the adsorber may be exhausted to the outside through a moisture outlet port 112a.

However, in an embodiment in which the electrochemical cell of the battery module <NUM> is a fuel cell, the moisture remover <NUM> may be omitted from the air supplier <NUM> if desired. Alternatively, a humidifier may be used in place of the moisture remover <NUM> if desired.

Air dried by the moisture remover <NUM> may be supplied to the oxygen generator <NUM>. The oxygen generator <NUM> may increase an oxygen concentration in air by removing impurities such as carbon dioxide and nitrogen included in the dried air. For example, the oxygen generator <NUM> may be configured to filter oxygen via an adsorption/desorption method or a membrane method. The oxygen, which is filtered by the oxygen generator <NUM> via the adsorption/desorption method or the membrane method, may be supplied to the battery module <NUM> through a first outlet port 113a. To this end, the first outlet port 113a of the oxygen generator <NUM> may be connected to an air inlet port 120a of the battery module <NUM>. A gas remaining after oxygen is separated may be exhausted to the outside through a second outlet port 113b.

As illustrated in <FIG>, the exhaust gas, which is exhausted through the first outlet port 113a or the second outlet port 113b, may be refluxed to the oxygen generator <NUM> so to facilitate selection of the oxygen concentration to a desired concentration. For example, a portion of the air, which is supplied to the battery module <NUM> through the first outlet port 113a, may be refluxed to the oxygen generator <NUM>. To this end, a first valve 114a may be disposed at a branch point of a reflux path, which is connected to the oxygen generator <NUM> through the first outlet port 113a. The controller <NUM> may control the first valve 114a to adjust an amount of the air which is refluxed from the first outlet port 113a to the oxygen generator <NUM>. In the same manner, a portion of the air, which is exhausted through the second outlet port 113b, may be refluxed to the oxygen generator <NUM>. To this end, a second valve 114b may be disposed at a branch point of a reflux path, which is connected to the oxygen generator <NUM> through the second outlet port 113b. The controller <NUM> may control the second valve 114b to adjust an amount of the air which is refluxed from the second outlet port 113b to the oxygen generator <NUM>.

In addition, an air flow passage <NUM> of the air recirculator <NUM> may be disposed to supply to the oxygen generator <NUM> air exhausted through an air outlet port 120b of the battery module <NUM>. Therefore mixed air of the dried outside air supplied through the air suction device <NUM> and the moisture remover <NUM> and the air exhausted through the air outlet port 120b of the battery module <NUM> may be supplied to the oxygen generator <NUM>. Since air is additionally supplied from the air outlet port 120b of the battery module <NUM>, the air suction device <NUM> may suction an oxygen amount that is less than an oxygen amount consumed by the battery module <NUM>. Accordingly, using this configuration selection of an air amount supplied to the oxygen generator <NUM> from the air outlet port 120b may be controlled. To this end, the air recirculator <NUM> may further include a third valve <NUM> disposed at the air flow passage <NUM>. The controller <NUM> may control the third valve <NUM> to adjust the air amount supplied to the oxygen generator <NUM> from the air outlet port 120b. The third valve <NUM> may be completely opened/closed or partially opened under control of the controller <NUM>. In addition, when a portion of the air supplied to the battery module <NUM> from the first outlet port 113a is refluxed to the oxygen generator <NUM>, the refluxed air may be mixed with the air dried by the moisture remover <NUM> and the air exhausted from the battery module <NUM>, and the mixed air may be supplied to the oxygen generator <NUM>.

<FIG> is a schematic block diagram of an oxygen generator <NUM> of the air supplier <NUM> illustrated in <FIG>, according to an embodiment. The oxygen generator <NUM> illustrated in <FIG> may be configured to filter oxygen via an adsorption/desorption method. In this case, the air supplier <NUM> may adjust the oxygen concentration in the air supplied to the battery module <NUM> by adjusting an adsorption amount of nitrogen in the air under control of the controller <NUM>. For example, referring to <FIG>, the oxygen generator <NUM> may include a first adsorber <NUM> and a second adsorber <NUM>, which are disposed in parallel to each other. The first adsorber <NUM> may include a first adsorbent 31a and a first recycler 31b. The second adsorber <NUM> may include a second adsorbent 32a and a second recycler 32b.

The first adsorbent 31a and the second adsorbent 32a may function to adsorb impurities such as nitrogen in air. For example, the first adsorbent 31a and the second adsorbent 32a may include at least one selected from zeolite LiX, alumina, a metal-organic framework (MOF), and a zeolite imidazolate framework (ZIF). The MOF may include a metal ion or a metal cluster which is coordinated to an organic molecule and may comprise a crystalline compound forming a primary, secondary, or tertiary porous structure. In addition, the ZIF may comprise a nanoporous compound including a tetrahedral cluster of the formula MN<NUM> that is linked by an imidazolate ligand (where M is a metal).

The first recycler 31b and the second recycler 32b may function to recycle the saturated first adsorbent 31a and the saturated second adsorbent 32a, respectively. In order to recycle the saturated first adsorbent 31a and the saturated second adsorbent 32a, the first recycler 31b and the second recycler 32b may be configured to adjust an inner pressure or temperature of the first adsorber <NUM> and an inner pressure or temperature of the second adsorber <NUM>, respectively.

The oxygen generator <NUM> having the aforementioned structure may operate, for example, in a pressure swing adsorption (PSA) method. For example, impurities such as nitrogen may be adsorbed to the first adsorbent 31a by increasing the inner pressure of the first adsorber <NUM>. The remaining air having an increased oxygen concentration may be exhausted from the first adsorber <NUM> to the first outlet port 113a. Also, the nitrogen adsorbed to the second adsorbent 32a may be desorbed from the second adsorbent 32a by decreasing the inner pressure of the second adsorber <NUM>, and the desorbed nitrogen may be exhausted from the second adsorber <NUM> to the second outlet port 113b. When the first adsorbent 31a is saturated, the inner pressure of the first adsorber <NUM> may be decreased, and the inner pressure of the second adsorber <NUM> may be increased. In this case, a desorbing operation may be performed in the first adsorber <NUM>, and an adsorbing operation may be performed in the second adsorber <NUM>. In such a manner, the first adsorber <NUM> and the second adsorber <NUM> may alternately operate. At this time, the oxygen concentration in the air supplied to the battery module <NUM> may be adjusted by adjusting the inner pressure of each of the first adsorber <NUM> and the second adsorber <NUM>.

However, an operation manner of the oxygen generator <NUM> is not limited to the PSA method, and any suitable method may be used. For example, in addition to the PSA method, the oxygen generator <NUM> may be configured to operate in at least one selected from a thermal swing adsorption (TSA) method, a pressure thermal swing adsorption (PTSA) method, and a vacuum swing adsorption (VSA) method. The PSA method means a technology of primarily adsorbing or capturing a specific gas to the first adsorbent 31a and the second adsorbent 32a at a high partial pressure, and desorbing or exhausting the specific gas when the partial pressure is decreased. In addition, the TSA method means a technology of primarily adsorbing or capturing a specific gas to the first and second adsorbents 31a and 32a at room temperature, and desorbing or exhausting the specific gas when the temperature is increased. The PTSA method means a technology in which the PSA method and the TSA method are combined. Finally, the VSA method means a technology of primarily adsorbing or capturing a specific gas to the first and second adsorbents 31a and 32a at about an atmospheric pressure, and desorbing or exhausting the specific gas under a vacuum.

<FIG> is a schematic block diagram of an oxygen generator <NUM> of the air supplier <NUM> illustrated in <FIG>, according to another embodiment. The oxygen generator <NUM> illustrated in <FIG> may be configured to filter oxygen via a membrane method. Referring to <FIG>, the oxygen generator <NUM> may include a pump <NUM> and an oxygen separation module <NUM> to be configured to separate nitrogen and oxygen in air. A membrane <NUM> may be disposed within the oxygen separation module <NUM> to selectively separate oxygen. One membrane <NUM> is illustrated in <FIG> for convenience, but a plurality of membranes <NUM>, e.g., about <NUM> to about <NUM> membranes, may be disposed in a multi-layered structure. For example, the membrane <NUM> may include Ba<NUM>Sr<NUM>Co<NUM>Fe<NUM>O<NUM>-δ (BSCF oxide).

The air dried by the moisture remover <NUM> may be supplied to the oxygen separation module <NUM>, and the membrane <NUM> in the oxygen separation module <NUM> may filter oxygen in air. According to demand, in order to improve separation efficiency by sufficiently supplying air to the oxygen separation module <NUM>, an air compressor may be further disposed between the moisture remover <NUM> and the oxygen separation module <NUM>. A gas remaining after oxygen is separated in the oxygen separation module <NUM> may be exhausted to the outside through the second outlet port 113b. The pump <NUM> may supply oxygen to the battery module <NUM> through the first outlet port 113a by emitting oxygen from the oxygen separation module <NUM>. At this time, in order to adjust the oxygen concentration in the air supplied to the battery module <NUM>, a portion of the air dried by the moisture remover <NUM> may be mixed with oxygen emitted from the pump <NUM>. For example, a valve <NUM> may be disposed between the moisture remover <NUM> and the pump <NUM>, and the controller <NUM> may control the valve <NUM> to adjust the oxygen concentration in the air supplied to the battery module <NUM>.

<FIG> is a schematic block diagram of an air supplier <NUM> and an air recirculator <NUM> of the electrochemical battery <NUM> illustrated in <FIG>, according to another embodiment. Referring to <FIG>, the air recirculator <NUM> may further include a membrane <NUM> configured to separate oxygen from air exhausted through an air outlet port 120b of a battery module <NUM>. The membrane <NUM> may be substantially the same as the membrane <NUM> illustrated in <FIG>. For example, the membrane <NUM> may be disposed within an air flow passage <NUM>. Therefore, the membrane <NUM> may separate only oxygen from air which is exhausted though the air outlet port 120b of the battery module <NUM> and is recirculated along the air flow passage <NUM>. The oxygen, which is separated by the membrane <NUM>, may continuously flow along the air flow passage <NUM> to be supplied to the battery module <NUM> through an air inlet port 120a. Air from which the oxygen has been filtered out by the membrane <NUM>, e.g., primarily nitrogen, may be exhausted to the outside through an outlet port 133a.

In the case of the present embodiment, since the oxygen in the air exhausted through the air outlet port 120b is separated by the membrane <NUM> within the air flow passage <NUM>, connection of the air flow passage <NUM> to an oxygen generator <NUM> can be omitted. As illustrated in <FIG>, the air flow passage <NUM> may be connected between the air inlet port 120a and the air outlet port 120b of the battery module <NUM>. For example, a first end portion of the air flow passage <NUM> may be connected to the air outlet port 120b, and a second end portion thereof may be connected to a first valve 114a or be directly connected to the air inlet port 120a. In this case, the air flow passage <NUM> may directly transfer the air exhausted through the air outlet port 120b to the air inlet port 120a. The air exhausted through the air outlet port 120b and air supplied through the oxygen generator <NUM> may be mixed to each other in the air inlet port 120a and be supplied to the battery module <NUM>.

In addition, in order to improve oxygen separation efficiency of the membrane <NUM> and allow air to smoothly flow in the air flow passage <NUM>, the air recirculator <NUM> may further include a pump <NUM>. For example, the pump <NUM> may be disposed on the air flow passage <NUM> between the air outlet port 120b and the membrane <NUM> and may allow air to flow from the air outlet port 120b to the air inlet port 120a.

Since the above-described electrochemical battery <NUM> maintains the oxygen concentration in the air supplied to the battery module <NUM> to a range greater than a range of an oxygen concentration in the atmosphere, the performance of the electrochemical battery <NUM> is improved. Also, a reduction in performance of the electrochemical battery <NUM>, which is caused by a low oxygen concentration, may be prevented, and degradation of a cathode material, which is caused by an excessively high oxygen concentration may be avoided. In addition, according to embodiments, the electrochemical battery <NUM> may constantly and efficiently maintain the oxygen concentration in the battery module <NUM> by recirculating the air exhausted from the battery module <NUM>. That is, since oxygen, which does not participate in a reaction within the battery module <NUM> and is exhausted therefrom is reused, it may be possible to reduce the amount of air supplied to the battery module <NUM> from the outside. Therefore, it may be possible to reduce an amount of electric power consumed for supplying air to the battery module <NUM>, for example, electric power consumed by the air suction device <NUM>, the moisture remover <NUM>, and the oxygen generator <NUM>.

<FIG> is a diagram illustrating that it is possible for an air amount supplied from the outside to be decreased by using the air recirculator <NUM> in a structure of the air supplier <NUM> and the air recirculator <NUM> illustrated in <FIG> in a case where the electrochemical cell of the battery module <NUM> is, for example, the metal air cell. In an example of <FIG>, it is assumed that an oxygen amount used for a reaction within the battery module <NUM> is about <NUM> liters per minute (L/min), and it is assumed that the controller <NUM> maintains an oxygen concentration in air supplied to the battery module <NUM> at about <NUM>%. In addition, it is assumed that a proportion of an amount of oxygen actually introduced to the battery module <NUM> to an oxygen amount used in the battery module <NUM> is about two. That is, when the oxygen amount used for the reaction within the battery module <NUM> is about <NUM>/min, about <NUM>/min of oxygen may be supplied to the battery module <NUM>. It is assumed that oxygen concentration efficiency of the oxygen generator <NUM> is about <NUM>%, and it is assumed that all of gases except for oxygen in air are nitrogen.

Referring to <FIG>, the air supplied through the air inlet port 120a of the battery module <NUM> may include about <NUM>/min of oxygen and about <NUM>/min of nitrogen. Since the battery module <NUM> consumes about <NUM>/min of oxygen during an operation, air exhausted through the air outlet port 120b may include about <NUM>/min of oxygen and about <NUM>/min of nitrogen. In this case, an oxygen concentration in the air exhausted through the air outlet port 120b may be about <NUM>%. All of the air exhausted through the air outlet port 120b may be transferred to the oxygen generator <NUM> through the air flow passage <NUM>. In order to extract about <NUM>/min of oxygen, the oxygen generator <NUM> having oxygen concentration efficiency of about <NUM>% may use about <NUM>/min of oxygen. Since about <NUM>/min of oxygen is supplied through the air flow passage <NUM>, the air suction device <NUM> additionally supplies about <NUM>/min of oxygen to the oxygen generator <NUM>. For example, since an oxygen concentration in the atmosphere is <NUM>%, the air suction device <NUM> may suction about <NUM>/min of oxygen and about <NUM>/min of nitrogen from the outside, the moisture remover <NUM> may remove moisture from the suctioned air, and then, the moisture-removed air may be supplied to the oxygen generator <NUM>. Accordingly, the whole air supplied to the oxygen generator <NUM> may include about <NUM>/min of oxygen and about <NUM>/min of nitrogen. After that, in order to maintain the oxygen concentration in the air supplied to the battery module <NUM> to about <NUM>%, the oxygen generator <NUM> may exhaust about <NUM>/min of oxygen and about <NUM>/min of nitrogen to the outside and supply <NUM>/min of oxygen and <NUM>/min of nitrogen to the battery module <NUM> under control of the controller <NUM>.

As can be seen from an example of <FIG>, when the air exhausted from the battery module <NUM> is recirculated by using the air recirculator <NUM>, the air suction device <NUM> suctions about <NUM>/min of air (about <NUM>/min of oxygen and about <NUM>/min of nitrogen). On the contrary, when the air exhausted from the battery module <NUM> is not recirculated, in order to supply about <NUM>/min of oxygen to the oxygen generator <NUM>, the air suction device <NUM> suctions about <NUM>/min of air (about <NUM>/min of oxygen and about <NUM>/min of nitrogen). About <NUM>/min of nitrogen is calculated by assuming that an oxygen concentration in the atmosphere is <NUM>%. Therefore, an amount of the air suctioned by the air suction device <NUM> may be reduced by about <NUM>% by recirculating the air exhausted from the battery module <NUM>, and a load of the air suction device <NUM> and the moisture remover <NUM> may be reduced by about <NUM>%.

<FIG> is a graph showing a decrease of an air supply flow rate and an oxygen concentration of air exiting the metal air battery according to an air supply ratio of an oxygen amount actually introduced into the battery module <NUM> to an oxygen amount used in the battery module <NUM> when an oxygen concentration in air supplied to the battery module <NUM> is fixed at a constant value in a case where the electrochemical battery cell of the battery module <NUM> is, for example, the metal air cell. For example, in a case where the oxygen amount used in the battery module <NUM> is about <NUM>/min, when about <NUM>/min of oxygen is supplied, the air supply ratio may be about one. When the air supply ratio is about one, the oxygen supplied to the battery module <NUM> may be completely consumed. Accordingly, the oxygen concentration in the air exhausted from the battery module <NUM> may be about <NUM>%. Therefore, an air supply flow rate may not be decreased in the air suction device <NUM>. Referring to the graph of <FIG>, as the air supply ratio of the oxygen amount actually introduced into the battery module <NUM> to the oxygen amount used in the battery module <NUM> is increased, the oxygen concentration in the air exhausted from the battery module <NUM> may be further increased, and the air supply flow rate may be further decreased in the air suction device <NUM>.

<FIG> is a graph showing a decrease of an air supply flow rate, an oxygen concentration of the air supplied to the battery module, and an oxygen concentration of air exiting the battery module according to oxygen concentration efficiency in the oxygen generator <NUM> when an air supply ratio of an oxygen amount actually introduced into the battery module <NUM> to an oxygen amount used in the battery module <NUM> is fixed to a constant value in a case where the electrochemical battery cell of the battery module <NUM> is, for example, the metal air cell. In the graph of <FIG>, it is assumed that the proportion of the oxygen amount actually introduced to the battery module <NUM> to the oxygen amount used in the battery module <NUM> is about two. Referring to <FIG>, as the oxygen concentration efficiency of the oxygen generator <NUM> is increased, the oxygen concentration in the air supplied to the battery module <NUM> and the oxygen concentration in the air exhausted from the battery module <NUM> may be increased, and the air supply flow rate may be decreased in the air suction device <NUM>.

As can be seen from the graphs of <FIG>, when taking into consideration the total efficiency of the electrochemical battery <NUM>, in an embodiment wherein the decrease effect of the air supply flow rate is not great in the air suction device <NUM>, it may be possible to stop recirculating air. That is, in an embodiment wherein the ratio of the oxygen amount actually introduced into the battery module <NUM> to the oxygen amount used in the battery module <NUM> is low, in an embodiment wherein the oxygen concentration efficiency of the oxygen generator <NUM> is low, or in a case where the oxygen concentration in the air exhausted from the battery module <NUM> is low, the controller <NUM> may stop recirculating the air by closing the third valve <NUM>. For example, the controller <NUM> may control the air recirculator <NUM> to recirculate or not to recirculate the air exhausted from the battery module <NUM> according to the oxygen concentration in the air exhausted from the battery module <NUM>. Specifically, when the oxygen concentration in the air exhausted from the battery module <NUM> is less than the oxygen concentration in the atmosphere (i.e., <NUM>%), the controller <NUM> may control the air recirculator <NUM> not to recirculate the air exhausted from the battery module <NUM>.

In <FIG>, in the case the electrochemical cell of the battery module <NUM> is the metal air cell, the effect of recirculating the air exhausted from the battery module <NUM> by using the air recirculator <NUM> has been described. Even when the electrochemical cell of the battery module <NUM> is the fuel cell, the efficiency of the electrochemical battery <NUM> may be improved by recirculating, to the air recirculator <NUM>, the air exhausted from the battery module <NUM>.

For understanding, embodiments of the electrochemical battery maintaining the oxygen concentration by air recirculation have been described and illustrated in the accompanying drawings. However, it will be understood that the embodiments are examples and shall not limit the scope of this disclosure. It will be understood that the scope of this disclosure is not limited to the illustrations and description provided herein and that various modifications may be made those of ordinary skill in the art.

Descriptions of features or aspects within each embodiment should be considered as available for other similar features or aspects in other embodiments.

Claim 1:
An electrochemical battery (<NUM>) comprising:
a battery module (<NUM>) comprising at least one electrochemical cell;
an air supplier (<NUM>) configured to supply air to the battery module (<NUM>) and maintain an oxygen concentration in the air that is supplied to the battery module (<NUM>), the air supplier (<NUM>) comprising an air suction device (<NUM>) configured to suction air from the outside, and an oxygen generator (<NUM>);
an air recirculator (<NUM>) configured to recirculate air exhausted from the battery module (<NUM>); and
a controller (<NUM>) configured to control the air supplier (<NUM>) and the air recirculator (<NUM>), and wherein the controller (<NUM>) is configured to maintain the oxygen concentration in the air supplied to the battery module (<NUM>),
wherein the battery module (<NUM>) comprises:
an air inlet port (120a) through which air is introduced from the air supplier (<NUM>); and
an air outlet port (120b) through which air remaining after a reaction in the at least one electrochemical cell is exhausted, and
wherein the air recirculator (<NUM>) is configured to recirculate the air exhausted through the air outlet port (120b) of the battery module (<NUM>) to the air inlet port (120a) of the battery module (<NUM>),
wherein the electrochemical battery (<NUM>) is characterised in that the oxygen generator (<NUM>) is configured to generate oxygen by separating oxygen from the suctioned air, and the air recirculator (<NUM>) comprises an air flow passage (<NUM>) connecting the air outlet port (120b) of the battery module (<NUM>) and the oxygen generator (<NUM>) such that mixed air of the air supplied through the air suction device (<NUM>) and the air exhausted through the air outlet port (120b) of the battery module (<NUM>) is supplied to the oxygen generator (<NUM>).