JP2013120680A - Water electrolysis hybrid storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water electrolysis hybrid storage battery capable of preventing overcharge without providing an expensive protective switch, or the like, corresponding to a high current and a large voltage and preventing burst, firing, and the like, of an enclosed storage battery such as a lithium ion storage battery due to overcharge of the emergency.SOLUTION: In a water electrolysis hybrid storage battery consisting of a virtual battery 32 constituted of parallel connection of enclosed storage batteries and water electrolytic device 26A, i.e., electrochemical cells using an aqueous solution as an electrolyte, or of a series connection of a plurality of virtual batteries, when overcharge energy leading to overcharge of the enclosed storage batteries is applied to the virtual battery, the water electrolytic device absorbs energy by performing electrolysis reaction of water, and prevents the charging voltage of the virtual battery from reaching the overvoltage dangerous voltage of the enclosed storage batteries.

Description

  The present invention relates to a water electrolysis hybrid storage battery in which a single or a plurality of virtual batteries formed by connecting in parallel a sealed storage battery such as a lithium ion storage battery and an electrochemical cell having an anti-overcharge function are connected in series.

  Conventional automobiles mainly using fossil fuel as driving energy have an adverse effect on the global environment due to the exhaust gas. On the other hand, widespread use of electric vehicles that do not emit exhaust gas or hybrid vehicles that significantly reduce their emissions is highly expected from the viewpoint of environmental improvement, and effective use of surplus power at night This is also recommended. In addition, it is desired to provide a distributed power storage system for power stabilization.

  However, there are problems such that the storage battery is very heavy, expensive, or low in safety. For example, an aqueous solution storage battery such as a lead storage battery having a low unit price per energy is very heavy, and an organic solution storage battery such as a lithium ion storage battery having a high energy density and a light weight is very expensive and has a problem in safety.

  Organic solution storage batteries such as lithium-ion storage batteries are not overcharged and are not flammable unlike aqueous storage batteries such as lead storage batteries. Because the electrolyte (electrolyte) is a combustible material, there is a risk of battery explosion due to overheating. . In order to solve such safety problems, a protection circuit and a protection switch for protecting an organic solution storage battery such as a lithium ion storage battery from overcharging have been conventionally used.

  For this reason, in the lithium ion storage battery, not only the cost of a single battery derived from an expensive battery material is high, but also the cost of electronic circuits and parts constituting the protection circuit and the protection switch is high, and the battery is very expensive. . As disclosed in Patent Document 1, the protection circuit and the protection switch referred to here measure the voltage and temperature of the battery and the current flowing through the battery. A protection circuit or protection switch that protects a battery by disconnecting the battery from a charge / discharge circuit when exposed to temperature or overcurrent.

  Conventionally, such a protection circuit and a protection switch are not necessary for a lead storage battery. However, as described above, the protection circuit and the protection switch are indispensable for a lithium ion storage battery because of dangers due to overvoltage, overtemperature, and overcurrent. In particular, preventing overcharging that has a serious impact on safety was the most important role for protection circuits and protection switches. Unlike portable devices such as mobile phones, laptop computers, and power tools, when a lithium-ion battery is used in an electric vehicle or power storage system, the specifications (rated) voltage and specifications (rated) current may be As a result, the specifications of the protection circuit and protection switch need to be compatible with large currents and voltages, and measures such as heat, resistance, and arc are required. There is a problem that the cost of the switch becomes very expensive.

  Further, the protection circuit and the protection switch are activated immediately even in the case of overcharge of about several milliseconds, and the lithium ion storage battery is disconnected from the power load circuit. In order to connect the lithium ion storage battery once disconnected from the circuit to the circuit again, for example, an operation of switching the protection switch after confirming the safety of the circuit through a plurality of procedures is required. Such disconnection of the lithium ion storage battery from the power load circuit, confirmation of safety, and switching of the protection switch are basically automatic operations, and no effort is required. However, there is a problem that a protection circuit software composed of a complicated algorithm is required, and development for verifying the reliability is very difficult and takes time.

  In addition, the lithium ion storage battery connected to the power load circuit is responsible for absorbing voltage fluctuations in the load circuit, but when the lithium ion storage battery is disconnected from the circuit by the protection circuit and the protection switch, it is the same as the lithium ion storage battery. There has been a problem that a voltage fluctuation load is directly applied to another electronic device connected to the power load circuit. Furthermore, since the timing at which the lithium ion storage battery is disconnected from the power load circuit by the protection circuit cannot be predicted, for example, when the lithium ion storage battery is used as a power source for an electric vehicle, the regenerative brake is switched to the normal brake. There were various problems in linking with other systems, such as difficulty in predicting and setting timing. The influence that can be exerted on the system by disconnecting the storage battery from the power load at an unexpected timing becomes more serious as the power capacity of the load circuit or the electrical capacity of the storage battery increases. For example, in the case of a stationary power storage device, the effects of disconnection and re-input from the power line are immeasurable. Therefore, it has been desired to improve the overcharge resistance of an organic solution storage battery such as a lithium ion storage battery and eliminate the need for disconnecting the battery from the circuit by a protection circuit or a protection switch.

  In the past, the inventor has connected in series a plurality of virtual batteries in which an organic solution storage battery and an aqueous solution storage battery are connected in parallel for the purpose of improving the overcharge resistance of an organic solution storage battery such as a lithium ion storage battery. A hybrid storage battery was proposed (Patent Document 1). According to this invention, the organic solution storage battery and the aqueous solution storage battery have close average discharge voltages, the overcharge danger voltage of the organic solution storage battery is higher than the end-of-charge voltage of the aqueous solution storage battery, and the organic solution storage battery It is comprised so that the charge end voltage of a storage battery may become lower than the charge end voltage of an aqueous solution type storage battery. With this configuration, when the virtual battery is given overcharge energy that leads to overcharging of the organic solution storage battery, the aqueous solution storage battery absorbs energy by performing a hydrogen generation reaction, and the virtual battery charge voltage is reduced to the aqueous solution storage battery. Therefore, it is possible to prevent the organic solution storage battery from reaching the overcharge danger voltage.

Japanese Patent Application No. 2011-2224070

  The hybrid storage battery disclosed in Patent Document 1 suppresses the voltage increase up to the overcharge danger voltage of the lithium ion storage battery by causing a hydrogen generation reaction of a lead storage battery connected in parallel with the lithium ion storage battery at the time of overcharging. It improves the overcharge resistance performance of the lithium ion storage battery. The present invention is suitable for use in a stationary power storage system or a large vehicle such as a bus or a truck with less space and weight restrictions because the energy density of the lead storage battery connected in parallel with the lithium ion storage battery is low. On the other hand, since the lead storage battery is very heavy, there is a problem that it is difficult to use it as a power source for a traveling body that requires a high weight energy density such as a small car, a sports car, and an airplane.

  Note that an organic solution storage battery such as a lithium ion storage battery is sealed in a sealed container so that water is not mixed in the electrolytic solution, and can be said to be a sealed storage battery. As specific examples of the sealed storage battery, in addition to the lithium ion storage battery, a calcium ion storage battery disclosed in JP-A-6-163080, JP-A-8-321305, and the like; Novak; Electrochem. Soc. , Vol. 140 No. 1, Jan (1993) 140 and M.I. E. Spahr; Examples include a magnesium ion storage battery disclosed in Power Sources 54 (1995) 346 and the like. In general, it can be said that all storage batteries having a configuration that adversely affects the electrode reaction in the positive electrode or the negative electrode or the ionic conduction in the electrolyte and the composition of the electrolyte when water is mixed in the electrolyte can be said to be a sealed storage battery.

  In light of the above, an object of the present invention is to provide a water-electrolytic hybrid storage battery that has good overcharge resistance and a relatively high energy density while being a storage battery including a sealed storage battery such as a lithium ion storage battery. There is.

  In order to achieve the above object, the water electrolysis hybrid storage battery of the present invention comprises a virtual battery formed by connecting a sealed storage battery and a water electrolysis device in parallel, or a plurality of the virtual batteries connected in series. A water electrolysis type hybrid storage battery, wherein the sealed storage battery is overcharged when charged exceeding a charge end voltage, and is in a dangerous state when charged beyond the overcharge danger voltage of the sealed battery The water electrolysis apparatus is a first water electrolysis cell group consisting of a plurality of water electrolysis cells connected in series or in series, or a plurality of water electrolysis cells connected in parallel, or connected in series. A plurality of the first water electrolysis cell groups, the water electrolysis cell having two electrodes and an electrolyte that is an aqueous solution, and the water electrolysis device starts the water electrolysis reaction when the voltage of the water electrolysis device is Less than voltage Both water electrolysis reactions occur in one of the water electrolysis cells, resulting in power consumption. The water electrolysis reaction start voltage of the water electrolysis device is higher than the overcharge danger voltage of the sealed storage battery. When the overcharged energy that leads to overcharging of the sealed storage battery is given to the virtual battery, power is consumed in the water electrolysis device, so that the overcharged energy is reduced. The sealed storage battery is prevented from reaching its overcharge dangerous voltage.

  Here, it is preferable that the water electrolysis reaction start voltage of the water electrolysis device is configured to be higher than the charge end voltage of the sealed storage battery.

  Moreover, it is preferable that the said water electrolysis apparatus has a catalyst which accelerates | stimulates the reaction in which water is produced | generated from oxygen and hydrogen.

Moreover, it is preferable that the electrode of the said water electrolysis cell contains the high surface area conductive material which is a conductive material whose specific surface area as a material particle is 10 m < ² > / g or more.
The high surface area conductive material is preferably activated carbon.

The water electrolysis device may be a nickel metal hydride storage battery.
Further, the water electrolysis device may be a nickel cadmium storage battery.

  Moreover, it is preferable that the water electrolysis type hybrid storage battery of this invention has a temperature control apparatus.

  Moreover, it is preferable that the said sealed storage battery is modularized so that attachment or detachment is possible as a cassette module.

  According to the present invention, power consumption occurs in the water electrolysis device even when overcharged, and the voltage of the entire storage battery is kept below the overcharge danger voltage of a sealed storage battery represented by a lithium ion storage battery or the like. Therefore, according to the present invention, it is possible to provide a water electrolysis type hybrid storage battery having good overcharge resistance while being a storage battery including a sealed storage battery such as a lithium ion storage battery. In addition, the overcharged water electrolysis device connected in parallel to a sealed storage battery such as a lithium ion storage battery does not contain an active material compared to a lead storage battery, and thus has a simple structure. A high-density configuration can be obtained.

The schematic diagram which shows schematic structure of one Embodiment of the water electrolysis type hybrid storage battery which concerns on this invention. The schematic diagram which shows schematic structure of one Embodiment of the lithium ion storage battery of the water electrolysis type hybrid storage battery shown in FIG. The schematic diagram which shows schematic structure of one Embodiment of the water electrolysis apparatus of the water electrolysis type hybrid storage battery shown in FIG. The schematic diagram which shows schematic structure of the water electrolysis cell which is one Embodiment of the water electrolysis apparatus shown in FIG. The schematic diagram which shows the one part schematic structure of FIG. 4 in detail. The voltage sweep result of the water electrolysis cell shown in FIG.4 and FIG.5. The overcharge test result in Example 1 of a water electrolysis type hybrid storage battery. (A) is a schematic diagram of the principal part of the 12V type | system | group water electrolysis type hybrid storage battery which is Example 2 of this invention, (B) is a schematic diagram which shows the structure of the 12V type conventional hybrid storage battery which is a prior invention, ( C) is a schematic diagram showing the configuration of a conventional 12V lithium ion storage battery.

  A water electrolysis type hybrid storage battery (battery) according to the present invention will be described below in detail based on a preferred embodiment shown in the accompanying drawings. Hereinafter, a lithium ion storage battery will be described as a representative example of the sealed storage battery constituting the water electrolysis hybrid storage battery of the present invention, but it goes without saying that the present invention is not limited to these.

  As shown in FIG. 1, the battery 10 according to the present invention includes a lithium ion storage battery unit 24 including a plurality (four in the illustrated example) of lithium ion storage batteries 24 </ b> A and a plurality (four in the illustrated example) of water electrolyzer 26 </ b> A. And a water electrolysis unit 26 made of The battery 10 has a structure in which virtual batteries 32 are connected in series. The virtual battery 32 is a battery in which a lithium ion storage battery 24A and a water electrolysis device 26A are connected in parallel. The battery 10 supplies electric energy by discharging to an external load such as each component of a moving body represented by an electric vehicle, for example. The battery 10 is charged by regenerative electric power generated by a regenerative brake of a moving body represented by an electric vehicle, for example. The battery 10 is charged by connecting a charger to an external power source (not shown) or the like. The battery 10 may be rapidly charged by an external charger (not shown) connected to a power source (not shown), for example, an external quick charger.

  The battery management system 19 controls the battery 10 and includes a virtual battery balance circuit unit 30 that aligns the charge levels between the virtual batteries 32 or maintains the balance thereof. The virtual battery balance circuit unit 30 includes one or a plurality of virtual battery balance circuits 30A. Each virtual battery balance circuit 30A is connected in parallel with each virtual battery 32, and the charge level of each virtual battery 32 is equalized or the balance is maintained. The battery management system 19 supplies electric energy to an external load, and abnormalities of the battery due to overdischarge, for example, deterioration of performance as a storage battery, shortening of life, and damage due to overcharge, for example, The discharge of the battery 10 is controlled so as not to cause danger such as rupture or ignition, and the charging of the battery 10 by regenerative power or a charger or the like is controlled.

  For example, the battery management system 19 controls a charging method, a charging condition, and a charging state so that the battery 10 is charged by a predetermined charging method, or each lithium ion storage battery 24A, each water electrolysis device 26A, each virtual battery 32. In order to observe the above state, a temperature sensor for measuring battery voltage, temperature, current, etc., a voltage / current sensor, or the like may be provided, or a function for outputting measurement data may be provided. In the prior art, when the lithium ion storage battery 24A is used, each lithium ion storage battery 24A requires a protection circuit and a protection switch for preventing abnormalities due to overcharge, such as overcharge and overdischarge. However, in the present invention, for the reason described later, the lithium ion storage battery 24A does not require a protection circuit or a protection switch for preventing abnormalities due to overcharging. Protection switch is not included.

  In the battery 10 of the present invention, each lithium ion storage battery 24A and each water electrolysis device 26A need to be connected in parallel to form each virtual battery 32, but a plurality (four in the illustrated example) of virtual batteries 32 are required. Are connected in series, so that a plurality (four in the illustrated example) of lithium ion storage battery units 24 consisting of lithium ion storage batteries 24A and a plurality (four in the illustrated example) of water electrolyzers connected in series are connected. The water electrolyzer unit 26 composed of 26A may be configured as a unit so that each lithium ion storage battery 24A and each water electrolyzer 26A are connected in parallel. By unitizing in this way, the same type of storage battery can be handled as a unit, and in particular, the cassette module of the lithium ion storage battery unit 24 can be easily made.

  When the lithium ion storage battery unit 24 is formed into a cassette module, when the overcharge resistance of the battery 10 is lowered, there is an advantage that the overcharge resistance of the battery 10 can be improved again by replacing only the water electrolysis device unit 26. That is, for example, when the battery 10 is repeatedly overcharged, the lithium ion storage battery unit 24 is protected from the overcharged state by the water electrolysis reaction of the water electrolyzer unit 26. It is considered that the performance deterioration is more significant than that of the lithium ion storage battery unit 24. In such a case, if the lithium ion storage battery unit 24 is formed as a cassette module, the performance of the battery 10 can be improved again only by replacing only the water electrolysis device unit 26. It goes without saying that such replacement of the water electrolyzer unit 26 can be performed even when the lithium ion storage battery unit 24 is not made into a cassette module, but water electrolysis is possible because the lithium ion storage battery unit 24 is made into a cassette module. The device unit 26 can be replaced more easily. Further, the cassette module of the lithium ion storage battery unit 24 is effective even when there is a case where it is desired to temporarily reduce the weight of the battery 10 even when sacrificing overcharge protection performance. For example, when the battery 10 is charged at a battery charging station having a power leveling function and is used as a drive source of an electric vehicle that does not have a regenerative brake or has a separate storage battery for the regenerative brake after charging, etc. This is the case.

  In addition, since the virtual battery balance circuit 30A is connected in parallel to each virtual battery 32 of the battery 10 of the present invention, the virtual battery balance circuit 30A, the lithium ion storage battery 24A, and the water electrolysis device 26A of the battery management system 19 are connected in parallel. Connected. Again, a plurality (four in the illustrated example) of virtual battery balance circuits 30A connected in series may be used as a unit as the virtual battery balance circuit unit 30. By using the virtual battery balance circuit unit 30 as a unit, handling of the virtual battery balance circuit 30A can be facilitated as a unit.

  In the present invention, in the lithium ion storage battery 24A and the water electrolysis device 26A connected in parallel constituting the virtual battery 32, the overcharge danger voltage of the lithium ion storage battery 24A is higher than the water electrolysis reaction start voltage of the water electrolysis device 26A. Need to be configured. Moreover, it is preferable that the charge termination voltage of the lithium ion storage battery 24A is configured to be lower than the water electrolysis reaction start voltage of the water electrolysis device 26A. Here, in the present invention, the overcharge dangerous voltage of the lithium ion storage battery 24A is a charge that may cause damage due to overcharge, such as danger such as rupture or ignition, if charged exceeding this voltage. The charge termination voltage of the lithium ion storage battery 24A is a charge voltage that may cause the lithium ion storage battery 24A to be overcharged when charged beyond this voltage, and may be a fully charged voltage or a fully charged voltage. it can. Further, in the present invention, the water electrolysis reaction start voltage of the water electrolysis device 26A means that when the voltage applied to the water electrolysis device 26A exceeds this voltage, a water electrolysis reaction occurs in the water electrolysis device 26A, and as a result, the water electrolysis device 26A. Is the voltage at which power consumption begins at.

  In the present invention, the overcharge risk voltage of the lithium ion storage battery 24A is configured to be higher than the water electrolysis reaction start voltage of the water electrolysis device 26A. The battery 10 of the present invention is charged, for example, a charger, regenerative power, etc. 24A, the lithium ion storage battery 24A is charged. However, even if a charging abnormality or the like occurs and the charging voltage increases and reaches the water electrolysis reaction start voltage of the water electrolysis device 26A, This is because an electrochemical reaction takes place in the electrolyzer 26A, thereby causing power consumption, and therefore, an increase in the charging voltage can be suppressed and the voltage of the battery 10 can be kept below the overcharge dangerous voltage.

  That is, when the lithium ion storage battery 24A falls into an overcharged state that may cause a significant performance deterioration that the lithium ion storage battery 24A itself cannot be used, and may cause a safety problem, Abnormalities such as shortening, in particular, damage due to overcharging, such as danger of explosion or ignition, are prevented beforehand by power consumption by water electrolysis in the water electrolysis device 26A. That is, it is possible to prevent an abnormality caused by an overcharge of the lithium ion storage battery 24A without providing an expensive protection circuit or protection switch, which has been indispensable for the lithium ion storage battery 24A due to safety problems. . Of course, the violent water electrolysis reaction in the water electrolysis device 26A degrades the performance of the water electrolysis device 26A and is dangerous in some cases. Therefore, the battery management system 19 is configured to stop the charge by managing the charge state. Needless to say, it has been done. On the other hand, in the present invention, it is preferable that the charge termination voltage of the lithium ion storage battery 24A be lower than the water electrolysis reaction start voltage of the water electrolysis device 26A. This is because it is preferable to completely charge the lithium ion storage battery 24A without causing a reaction.

  In the battery 10 of the present invention, the lithium ion storage battery 24A may be composed of one lithium ion cell that is a lithium ion single battery, or a plurality of lithium ion cells connected in series to form a predetermined voltage. As shown in FIG. 2, a plurality (four in the illustrated example) of lithium ion cell groups 24C in which a plurality of lithium ion cells 24B are connected in parallel are connected in series. It may be configured so as to be connected to a voltage of a predetermined voltage.

  In the case where a plurality of lithium ion cells are connected in series to have a predetermined voltage, a cell balance circuit for aligning the charge balance between the plurality of lithium ion cells 24B connected in series. The unit 34 is preferably provided so that the cell balance circuit 34 included in the cell balance circuit unit 34 is connected in parallel for each lithium ion cell 24B. In addition, as shown in FIG. 2, when a plurality of (four in the illustrated example) lithium ion cell groups 24C are connected in series so as to have a predetermined voltage, the plurality of series connected in series. It is preferable to provide a cell balance circuit 34A for aligning the charge balance between the lithium ion cell groups 24C so as to be connected in parallel for each lithium ion cell group 24C. Here, the cell balance circuit 34 equalizes the charge level of each lithium ion cell 24B or maintains the balance.

As the lithium ion storage battery 24A used in the present invention, lithium iron phosphate (LiFePO ₄ ) is used as a positive electrode active material, a carbon-based or silicon-based active material is used as a negative electrode, and the average operating voltage of a single cell is 3.3V. A lithium iron phosphate battery using a 3.3 V lithium ion cell (hereinafter also referred to as an LFPO lithium ion battery), lithium nickel manganese cobalt composite oxide (NMC), lithium nickel cobalt as a positive electrode active material An aluminum composite oxide (NCA), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), etc. were used, and a 3.6 V lithium ion cell having an average operating voltage of 3.6 V was used. Lithium ion storage battery etc. can be mentioned, and in addition, the conditions required for the present invention If the Suyo lithium-ion battery, it may be used any lithium-ion batteries. Here, the αV storage battery means that the average operating voltage is αV.

  In addition, as described above, a general lithium ion storage battery is overcharged or overdischarged separately from a balance circuit that balances the voltage and charge balance between the storage batteries, causing an abnormality due to overcharge and overdischarge. A protection circuit or a protection switch is provided as an essential component in order to prevent the life from being significantly impaired. The protection circuit or the protection switch is very expensive and costs almost the same as the lithium ion storage battery alone.

  However, in the virtual battery 32 of the present invention, the lithium ion storage battery 24A is connected in parallel with the water electrolysis device 26A, and before the lithium ion storage battery 24A reaches the overcharge danger voltage, the water electrolysis device 26A has an electrochemical reaction start voltage. Therefore, electric energy is consumed in the water electrolysis device 26A, and therefore, there is little risk that the lithium ion storage battery 24A is overcharged and thus enters an abnormal state. That is, since the water electrolysis device 26A serves as a protection circuit or a protection switch provided in the conventional lithium ion storage battery, the cost of the protection circuit or the protection switch can be reduced, and the cost for the battery can be greatly reduced. It becomes possible. It should be noted that the voltage and temperature information that the charging voltage is excessively high, or as a result, the water electrolysis device 26A violently undergoes an oxidation-reduction reaction and becomes high temperature is measured by the battery management system 19 and recorded or recorded at a later date. Data is transferred for correction (maintenance such as replacement of defective batteries).

  Below, the water electrolysis apparatus and water electrolysis cell which concern on the water electrolysis type hybrid storage battery of this invention are demonstrated.

  In the battery 10 of the present invention, the water electrolysis device 26A may be composed of one water electrolysis cell, which will be described later, or a predetermined water electrolysis reaction start voltage by connecting a plurality of water electrolysis cells in series. As shown in FIG. 3, a plurality (four in the illustrated example) of water electrolysis cell groups 26C in which a plurality of water electrolysis cells 26B are connected in parallel are connected in series. It may be configured so as to be connected to a voltage of a predetermined voltage.

  FIG. 4 is a schematic diagram showing a schematic configuration of one embodiment of the water electrolysis cell according to the present invention. FIG. 5 is a schematic diagram showing the schematic configuration of a part of FIG. 4 in more detail.

  As shown in FIG. 5, the water electrolysis cell 200 has two electrode layers 210, an electrolyte layer 230, and leads 240. Each electrode layer 210 includes a conductive material 211 and a current collector 212. The electrolyte layer 230 includes a separator 231 and an electrolyte 232 that is an aqueous solution. The separator 231 has a role of isolating and electrically insulating each electrode layer 210 and a role of holding the electrolyte 232. The separator 231 is filled with the electrolyte 232, and a part of the electrolyte 222 is exposed from the surface of the separator 221 and penetrates into the conductive material 211 as shown in FIG. 5. The electrolyte 232 penetrates into the conductive material 211, and the surface of the conductive material 211 is in contact with the electrolyte 232. The lead 240 is electrically connected to the current collector 112 in any one of the electrode layers 110, and is electrically connected to an external circuit not shown in FIGS.

  In the electrolyte 232 of the water electrolysis cell 200, when the voltage between the two electrodes exceeds a certain value (electrochemical reaction start voltage), an electrolysis reaction of water in the electrolyte 232 that is an aqueous solution occurs, and as a result, the water electrolysis cell Power is consumed within 200.

As described above, the electrode layer 210 includes the conductive material 211 and the current collector 212. The electrolysis reaction of water in the electrolyte 232 occurs on the surface of the conductive material 211 in each electrode layer 210, and the conductive material 211 preferably has a specific surface area of 10 m ² / g or more, and 100 m ² / g or more. It is more preferable to have a specific surface area of The larger the specific surface area of the conductive material, the faster the water electrolysis reaction occurs, and thus the power consumption per unit weight of the water electrolyzer 26A becomes very large.

  An example of the conductive material 211 is activated carbon. Activated carbon is used for electrodes of electric double layer capacitors, which is one of the reasons why electric double layer capacitors have a higher output density than storage batteries such as lithium ion storage batteries. When activated carbon is used as the conductive material 211, it is used by mixing with a binder such as polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE) in order to improve the adhesion to the current collector 212. Is preferred.

  The current collector 212 has a role of exchanging electrons with the conductive material 211 and needs to exist stably within an applied voltage range. Examples of suitable materials include titanium, gold, silver, platinum, carbon paper, carbon felt and the like. There is no particular limitation on the method for installing the conductive material 211 on the current collector 212. However, the conductive material 211 may be applied to the current collector 212 or may be bonded to the current collector 212 after a sheet of the conductive material is formed in advance. There are ways to do this. The shape of the current collector 212 includes a sheet shape, a mesh shape, a nonwoven fabric shape, and a woven fabric shape. In some cases, the conductive layer 211 may not be provided, and the electrode layer 210 may be composed only of the current collector 212.

The separator 231 may be anything as long as it has electrical insulation and good retention of the electrolyte 232, but preferably has the following characteristics.
1 To be as thin as possible to reduce internal resistance 2 To have a low density 3 To have good wettability with the electrolyte (electrolyte) 4 To be stable to the electrolyte (electrolyte) 5 To contain impurities that cause redox reactions No 6 Good thermal stability 7 No nests or pinholes Suitable examples of separator 231 include nonwoven paper, porous resin sheet, polyolefin microporous film, polyolefin mesh, ultra-thin glass There are papers and the like, and commercially available separators used for lithium ion storage batteries may be used.

  The electrolyte 232 may be anything as long as it is an aqueous solution, and preferred examples include an aqueous solution of sulfuric acid, an aqueous solution of nitric acid, an aqueous solution of potassium hydroxide, an aqueous solution of sodium hydroxide, and an electrolytic solution used in a general aqueous battery.

  In addition, it is preferable that the water electrolysis apparatus comprised from a water electrolysis cell or a water electrolysis cell has a catalyst which accelerates | stimulates the reaction in which water is produced | generated from oxygen and hydrogen. This is because water is again formed from hydrogen and oxygen generated by electrolysis of water by the catalyst, and there is no need to supply water to the water electrolysis cell or the water electrolysis apparatus. Preferable examples of the catalyst include palladium.

  In the water electrolysis cell of the present invention, as shown in FIG. 4, two electrode layers 210 and an electrolyte layer 230 having a sheet shape are laminated in the order of a positive electrode layer 210, an electrolyte layer 230, a negative electrode layer 320, and an electrolyte layer 330. The layer may be a cylindrical structure in which the layers are wound, and the lead 340 is connected to a location in the cylindrical central portion of the two electrode layers 210. For example, a structure in which a large number of two electrode layers 210 and electrolyte layers 230 each having a sheet shape are stacked and accommodated in a rectangular case may be used.

  In the water electrolysis type hybrid storage battery of the present invention, the water electrolysis cell 26B or the water electrolysis device 26A may have the same configuration as the nickel cadmium storage battery or the nickel hydrogen storage battery. These have a higher energy density compared to lead-acid batteries, and therefore can be water-electrolytic hybrid batteries having a higher energy density than conventional hybrid batteries using lead-acid batteries.

  Although not explicitly shown in FIGS. 1 to 3, the water electrolysis device 26 </ b> A may include two or more types of water electrolysis cells 26 </ b> B. For example, the water electrolysis apparatus 26A includes a plurality of water electrolysis cells having potassium hydroxide as the main component of the electrolyte, a plurality of water electrolysis cells connected in series, or a group of water electrolysis cells connected in parallel. One connected in series and another water electrolysis cell having dilute hydrochloric acid as the main component of the electrolyte, or a plurality of other water electrolysis cells connected in series, or a group of these other water electrolysis cells connected in parallel May be configured by connecting in parallel a plurality of these connected in series.

Example 1
Hereinafter, examples of the water electrolysis type hybrid storage battery will be described.

  (Preparation of water electrolysis cell) Activated carbon carrying manganese oxide was used as a conductive material, mixed with a PTFE binder, and kneaded into a titanium mesh as a current collector (5Ti7-077 manufactured by Dexmet) to prepare a positive electrode. The titanium mesh was used for the negative electrode. These electrodes were cut to a width of 2.5 cm and a length of 25 cm, and a 5 mm wide titanium ribbon was attached to one end by welding as a lead. A polypropylene mesh was inserted as a separator between the positive electrode and the negative electrode, and these were wound up and placed in a polypropylene container having a diameter of 3 cm and a depth of 5 cm, and a 1% sulfuric acid solution was used as an electrolyte to prepare a water electrolysis cell.

  (Estimation of water electrolysis reaction start voltage) The water electrolysis cell was installed in a charge / discharge test apparatus, the voltage was changed at a scan rate of 50 mV / s, and the change in the current value was measured. The results are shown in FIG. As shown in FIG. 6, when the terminal voltage exceeded 2.05V, the current increased rapidly, and when the terminal voltage reached 2.8V, the current amount reached 3750 mA (60 mA / cm 2). From this result, it was shown that the water electrolysis cell had an electrochemical reaction initiation voltage of 2.05V.

  (Preparation of lithium ion storage battery) A lithium nickel aluminum cobalt oxide was used as a positive electrode, graphite was used as a negative electrode, and a polypropylene porous film was used as a separator to prepare a 3.6 V lithium ion pouch cell. When this lithium ion pouch cell was installed in a charge / discharge test apparatus and a charge / discharge test was performed, the overcharge danger voltage of the lithium ion pouch cell was 4.6V, the complete charge voltage was 4.05V, and the capacity was 40 mAh. .

  (Preparation of water electrolysis type hybrid storage battery) The lithium ion pouch cell and two water electrolysis cells connected in series were connected in parallel to obtain a water electrolysis type hybrid storage battery. In this water electrolysis type hybrid storage battery, since the two water electrolysis cells in series are used as the water electrolysis device, the electrochemical reaction starting voltage is 4.1V.

  (Overcharge test) The prepared water electrolysis hybrid storage battery is installed in a charge / discharge test apparatus, and the lithium ion pouch cell in the water electrolysis hybrid storage battery is discharged to an open circuit voltage of 3 V from 80 mA (in terms of lithium ion pouch cell) The battery was charged at a charge rate of 2C). During this charging, 400 mA (10 C in terms of lithium ion pouch cell) and 30 seconds of pulse charging were performed twice. As Comparative Example 1, the same test was performed using only a lithium ion pouch cell. In order to ensure safety in this experiment, the test is forcibly terminated when the voltage of the storage battery exceeds 4.6 V, which is the overcharge danger voltage of the lithium ion pouch cell, or the next charging schedule is entered. It is set to migrate. The result of the overcharge test is shown in FIG. In the water electrolysis type hybrid storage battery of Example 1, the fully charged voltage reached 4.05 V within 30 minutes. Thereafter, charging was continued at 80 mA (charging rate 2C), but even after the charging time exceeded 1 hour, the voltage did not exceed the electrochemical reaction starting voltage 4.1V. Theoretically, the total current supply at this point corresponds to 200% of the lithium ion pouch cell capacity. In addition, when a 400 mA pulse charging current was applied for 30 seconds, the voltage rose to around 4.5 V, but did not exceed 4.6 V, which is an overcharge danger voltage of the lithium ion pouch cell. On the other hand, in Comparative Example 1 having no water electrolysis apparatus, charging was performed at 80 mA (charging rate 2 C) from the state where the open circuit voltage was discharged to 3 V, and the voltage was fully charged in about 5 minutes from the start of charging. The voltage reached 4.05V. As charging continued at the same rate, the voltage continued to rise. When a 400 mA pulse charging current was applied during this period, the voltage reached 4.6 V, which was an overcharge danger voltage, immediately after the pulse charging current was applied, and the application of the pulse charging current stopped. This result has shown that the water electrolysis apparatus comprised with a water electrolysis cell contributed to suppressing the overcharge of a lithium ion pouch cell. That is, in Example 1, the voltage value did not exceed 4.1 V even after the charging current of 80 mA flowed for 1 hour because the water electrolysis apparatus when the voltage of Example 1 reached 4.1 V It is considered that water electrolysis occurred in the water electrolysis cell constituting the structure and power consumption was performed. Further, even when 400 mA pulse current was applied for 30 seconds, power consumption by the water electrolysis cell occurred, so that although the voltage rose to 4.1 V or more, which is the water electrolysis reaction start voltage, due to polarization, the voltage rise of Example 1 Is considered to be suppressed to a value lower than 4.6 V, which is the overcharge danger voltage of the lithium ion pouch cell.

(Example 2)
Examples relating to a 12V water-electrolytic hybrid storage battery will be described in detail below.

(Preparation of water electrolysis apparatus) One side of an aluminum current collector foil is made of a conductive material paste containing 90% activated carbon having a specific surface area of 1000 m ² / g as a conductive material and 10% polyvinylidene fluoride as a binder in a weight ratio. The electrode was produced by applying to a thickness of 50 μm. Two of the above electrodes were prepared, and an aluminum tab lead terminal was joined to each electrode on the side where the activated carbon was not applied by caulking. Thereafter, the side of each electrode to which the conductive material paste was applied was opposed, wound between both electrodes via a separator, dried, and then impregnated with 1% sulfuric acid solution as an electrolyte. Thereafter, the whole was enclosed in an aluminum case to obtain a water electrolysis cell. When the weight of this water electrolysis cell was measured, it was 150 g. Two water electrolysis cells were connected in series to obtain a water electrolysis apparatus. When this water electrolysis apparatus was connected to a charge / discharge test apparatus, the voltage was changed at a scan rate of 50 mV / s and the change in the current value was measured, the current value increased rapidly at a terminal voltage of 4.1V. Therefore, the water electrolysis apparatus composed of two water electrolysis cells connected in series has a water electrolysis reaction starting voltage of 4.1V.

  (Production of Water Electrolytic Hybrid Storage Battery) A lithium-ion storage battery 24A in which 25 pieces of 26650-type lithium ion cells (model name ANR26650M1B, rated voltage 3.3V, capacity 2.4Ah, weight 76g) manufactured by A123, A virtual battery was obtained by connecting in parallel a water electrolysis device 26A composed of a water electrolysis cell. Four virtual batteries were connected in series to obtain a 12V water electrolysis hybrid storage battery shown in FIG.

The charging characteristics of the lithium ion storage battery section and the water electrolysis apparatus section in the 12V water electrolysis hybrid storage battery of the present invention shown in FIG.
Overcharge danger voltage of lithium ion battery part 17.6V
Water electrolysis reaction start voltage of water electrolysis unit 16.4V
End-of-charge voltage of lithium-ion battery (= full charge voltage) 14.5V

  When the charging voltage of the 12V water electrolysis type hybrid storage battery 10 of the present invention increases, the electrochemical reaction start voltage (2) of the water electrolysis device section 26 is higher than the overcharge danger voltage (1) of the lithium ion storage battery section 24. Since the water electrolysis reaction occurs in the water electrolysis device part before the lithium ion storage battery part reaches the overcharge danger voltage (1) and electric energy is consumed because it is low, the water electrolysis type hybrid storage battery 10, and thus the lithium ion An increase in charging voltage applied to the storage battery unit 24 is suppressed.

  (Comparative Experiment 1) As a comparative example of FIG. 8 (A), a 12V type conventional hybrid storage battery shown in FIG. 8 (B) is connected to a 26650 type lithium ion cell manufactured by A123, 4S-2P, and AC It was obtained by connecting in parallel a lead storage battery 36A (model name S55B24L, rated voltage 12V, capacity 36Ah, weight 1280g) manufactured by DELCO. Further, as another comparative example, a 12V type conventional lithium ion storage battery shown in FIG. 8C is obtained by adding a protection circuit to the A123 company 26650 type lithium ion cell connected to 4S-25P. It was.

  8A to 8C do not show a balance circuit that keeps the balance of the charge capacity of each storage battery within a predetermined range, but these batteries include each series cell, series storage battery, and series virtual battery. Of course, it has a balance circuit that adjusts the balance of the charging capacity.

The result shown in Table 1 was obtained as a result of connecting the storage battery of the structure shown to FIG. 8 (A)-(C) to the charging / discharging test apparatus, and performing the charging / discharging test.

  As shown in Table 1, in the storage batteries of these configuration examples A to C, the water electrolysis type hybrid storage battery of the configuration example A of the present invention has an energy density, excess energy compared to the storage batteries of the configuration examples B and C of the conventional example. All of the charging power density is excellent, and it can be said that it is the most excellent overall.

  The effect of the present invention of the configuration example A shown in Table 1 described above is that, from the viewpoint of energy density, the use of a water electrolysis device composed of water electrolysis cells eliminates the need for a protection circuit for a lithium ion storage battery. It is thought that it contributed. From the viewpoint of overcharge power density, it is considered that the water electrolysis apparatus has an overcharge permissible current per unit weight much larger than that of the lead storage battery.

10 Water-electrolytic hybrid storage battery (battery)
19 Battery management system 24 Lithium ion storage battery part 24A Lithium ion storage battery 24B Lithium ion cell 24C Lithium ion cell group 26 Water electrolysis apparatus part 26A Water electrolysis apparatus 26B Water electrolysis cell 26C Water electrolysis cell group 30 Virtual battery balance circuit part 30A Virtual battery balance Circuit 32 Virtual battery 34 Cell balance circuit part 34A Cell balance circuit 36 Lead storage battery 200 Water electrolysis cell 210 Electrode layer 211 Conductive material 212 Current collector
230 Electrolyte layer 231 Separator 232 Electrolyte
234 Solvent 240 lead

Claims (9)

A water-electrolytic hybrid storage battery consisting of a virtual battery formed by connecting a sealed storage battery and a water electrolysis device in parallel, or a plurality of the virtual batteries connected in series,
The sealed storage battery is overcharged when charged beyond the end-of-charge voltage, and reaches a dangerous state when charged over the overcharge danger voltage of the sealed battery.
The water electrolysis apparatus includes a single or a plurality of water electrolysis cells connected in series, a first water electrolysis cell group composed of a plurality of water electrolysis cells connected in parallel, or a plurality of the first electrolysis cells connected in series. Consists of water electrolysis cells,
The water electrolysis cell has two electrodes and an electrolyte that is an aqueous solution,
In the water electrolysis device, when the voltage of the water electrolysis device exceeds a water electrolysis reaction start voltage, an electrolysis reaction of water occurs in at least one of the water electrolysis cells, resulting in power consumption.
The water electrolysis reaction start voltage of the water electrolysis device is configured to be lower than the overcharge danger voltage of the sealed battery,
The overcharge energy is absorbed by power consumption in the water electrolysis device when the overcharge energy to the overcharge of the closed battery is given to the virtual battery, and the closed battery is A water electrolysis type hybrid storage battery characterized in that the battery is prevented from reaching the overcharge dangerous voltage.   The water electrolysis hybrid storage battery according to claim 1, wherein a water electrolysis reaction start voltage of the water electrolysis apparatus is configured to be higher than a charge end voltage of the sealed storage battery.   The water electrolysis type hybrid storage battery according to claim 1 or 2, wherein the water electrolysis device has a catalyst that promotes a reaction of generating water from oxygen and hydrogen. The water electrolysis type hybrid storage battery according to any one of claims 1 to 3, wherein the electrode of the water electrolysis cell includes a high surface area conductive material which is a conductive material having a specific surface area of 10 m ² / g or more as material particles.   The water electrolysis type hybrid storage battery according to any one of claims 1 to 4, wherein the high surface area conductive material is activated carbon.   The water electrolysis type hybrid storage battery according to any one of claims 1 to 5, wherein the water electrolysis device is a nickel metal hydride storage battery.   The water electrolysis type hybrid storage battery according to any one of claims 1 to 6, wherein the water electrolysis device is a nickel cadmium storage battery.   The water electrolysis type hybrid storage battery according to any one of claims 1 to 7, comprising a temperature control device.   The water electrolysis type hybrid storage battery according to any one of claims 1 to 8, wherein the sealed storage battery is modularized so as to be detachable and replaceable as a cassette module.