Energy storage element

Abstract

It efficiently generates and outputs stable electricity from unstable electricity generated from natural energy sources, etc. [Solution] The energy storage element comprises a first electrode having a first polarity current collector 31 and an active material layer 32, a second electrode having a second polarity current collector 35 and an active material layer 34, a separator 33 sandwiched between the two electrodes, a first charging terminal 31' connected to the first polarity current collector 31, a second charging terminal 35' connected to the second polarity current collector 35, a third discharge terminal 31' connected to the first polarity current collector 31 and separated from the first terminal 31', and a fourth terminal connected to the second polarity current collector 35 and either identical to or separated from the second terminal 35', and the maximum current supplied by the power generation unit is I INMAX The rated input current of the storage battery is I BR The longer of the distance between the first terminal 31' and the second terminal 35' and the distance between the third terminal 31' and the fourth terminal is L. P-N The distance between the first terminal 31' and the third terminal 35' is L P-P When defined as such, it satisfies formula 1 in the specification.

Description

[Technical Field]

[0001] This invention relates to an energy storage element. [Background technology]

[0002] Power generation and storage units and energy storage elements using solar panels are known (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 7042527 [Patent Document 2] Patent No. 7072925 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The power generation and storage units and storage elements described above may not be able to efficiently generate and output stable power from unstable power generated from natural energy sources.

[0005] This invention was devised in light of these challenges, and aims to provide an energy storage element applicable to a storage and discharge system that efficiently generates and outputs stable power from unstable power generated from natural energy sources. However, this is not the only objective; another objective of this invention is to achieve effects and benefits that cannot be obtained by conventional technology, resulting from the various configurations shown in the embodiments for carrying out the invention described later. [Means for solving the problem]

[0006] A power storage element according to one aspect of the present invention, which solves the above problems, is a power storage element that constitutes a battery capable of charging DC power supplied from a power generation unit. It comprises a first electrode having a first polarity current collector and an active material layer formed on the surface of the first polarity current collector, a second electrode having a second polarity current collector and an active material layer formed on the surface of the second polarity current collector, a separator sandwiched between the first electrode and the second electrode, a first charging terminal connected to the first polarity current collector, a second charging terminal connected to the second polarity current collector, a third discharge terminal connected to the first polarity current collector and separated from the first terminal, and a fourth terminal connected to the second polarity current collector and identical to or separated from the second terminal. The maximum current supplied by the power generation unit is I INMAX , the rated input current of the storage battery is I BR The longer of the distance between the first and second terminals and the distance between the third and fourth terminals is L. P-N The distance between the first terminal and the third terminal is L P-P If defined as such, then the following equation 1 is obtained.

number

[0007] The disclosed energy storage element makes it possible to realize a storage and discharge system that can generate stable power with high efficiency. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram illustrating a storage and discharge system according to the first embodiment. [Figure 2] Figures (a) to (d) illustrate the charging and discharging operation of the two-terminal element according to the same embodiment. [Figure 3] (a) and (b) are diagrams illustrating the movement of electrons and lithium ions in a two-terminal element with a tab structure on both sides in the same embodiment. [Figure 4](a) and (b) are diagrams for explaining the movement of electrons and lithium ions in a two-terminal element with a single-sided tab structure in the same embodiment. [Figure 5] It is a diagram illustrating the configuration of a storage battery using the two-terminal element according to the same embodiment. [Figure 6] It is a block diagram illustrating a charge-discharge system according to a first comparative example with respect to the same embodiment. [Figure 7] It is a block diagram illustrating a charge-discharge system according to a second comparative example with respect to the same embodiment. [Figure 8] (a) and (b) are diagrams for explaining the influence of the output voltage of a solar power generator in a charge-discharge system according to the first and second embodiments. [Figure 9] It is a diagram illustrating a first configuration of a three-terminal element according to the second embodiment. [Figure 10] (a) and (b) are diagrams illustrating a second configuration of a three-terminal element according to the same embodiment. [Figure 11] (a) and (b) are diagrams showing the configuration of a three-terminal element according to a comparative example with respect to the same embodiment. [Figure 12] It is a diagram for explaining the movement of electrons and lithium ions in a second configuration of a three-terminal element according to the same embodiment. [Figure 13] It is a diagram illustrating the configuration of a storage battery using the three-terminal element according to the same embodiment. [Figure 14] It is a diagram illustrating another configuration of a storage battery using the three-terminal element according to the same embodiment. [Figure 15] It is a block diagram illustrating a charge-discharge system including a wind power generator according to the third embodiment. [Figure 16] It is a block diagram illustrating a charge-discharge system including a plurality of wind power generators according to the same embodiment. [Figure 17] It is a block diagram illustrating a charge-discharge system including a solar power generator, a wind power generator, and a hydroelectric generator according to the same embodiment.

Embodiments for Carrying Out the Invention

[0009] The storage and discharge system and energy storage elements as embodiments will be described with reference to the drawings. The embodiments shown below are merely illustrative, and there is no intention to exclude various modifications and applications of technologies not explicitly shown in the embodiments below. The configuration of these embodiments can be modified in various ways without departing from their spirit. Furthermore, they can be selected or combined as needed.

[0010] [1. First Embodiment] Figure 1 is a block diagram illustrating an embodiment of the storage and discharge system 100.

[0011] The storage and discharge system 100 comprises one or more storage batteries 1, one or more solar panels 2A (solar generators), a D-CS (Direct-Charge System) 3, and a DC / AC inverter 4.

[0012] The storage battery 1 may be, for example, a lithium-ion secondary battery (hereinafter simply referred to as "lithium-ion battery"), preferably a manganese-based lithium-ion battery.

[0013] Battery 1 is connected in parallel to solar panel 2A via D-CS3. D-CS3 has a function to shut off the input or output circuit based on the battery voltage to prevent overcharging and over-discharging of battery 1. However, in the normal charging and discharging state, solar panel 2A and battery 1 are directly connected, and it is also directly connected to DC / AC inverter 4. Note that D-CS3 may simply be a switch.

[0014] Since the storage battery 1 is connected in parallel with the solar panel 2A, the panel voltage (e.g., 300V to 400V) is fixed to the battery voltage. Different from the system equipped with the MPPT (Maximum Power Point Tracking) circuit (described later using FIGS. 6 and 7), in the power storage and discharge system 100 shown in FIG. 1, the panel voltage is constant. Exactly speaking, the panel voltage is the voltage rise due to the cable resistance and current up to the storage battery 1, but basically it is the battery voltage. The converted energy (power) P of solar power generation is converted into the current represented by I = P / V.

[0015] The input voltage to the DC / AC inverter 4 is fixed to the battery voltage, and the required power fluctuation is dealt with by the change in the current amount. When the required current of the DC / AC inverter 4 is smaller than the generated current, it is supplied by the current from the solar panel 2A, and the surplus current automatically goes to the charging of the storage battery 1. Also, when the required current of the DC / AC inverter 4 is larger than the generated amount of the solar panel 2A, the insufficient current is automatically discharged from the storage battery 1.

[0016] The solar panel 2A may function as an example of a power generation unit having a first internal resistance and supplying DC power from the output terminals. The storage battery 1 may be connected in parallel with the output terminals of the power generation unit and have a second internal resistance lower than the first internal resistance. The DC power discharged by the storage battery 1 may be converted into at least one of the desired AC power or DC power and output. The voltage V of the output terminals of the power generation unit IN is the voltage of the storage battery 1 as V B , the current flowing from the output terminals of the power generation unit is I IN , and the wiring resistance between the power generation unit and the storage battery 1 is R IN-B When defined as such, V IN = V B + I IN × R IN-B It may be controlled by.

[0017] The first internal resistance fluctuates according to the environmental temperature of the power generation unit, and the second internal resistance may be lower than the minimum value of the first internal resistance.

[0018] Next, we will describe battery 1 in detail. A storage battery 1 is composed of one or more energy storage elements (cells). Each energy storage element is typically composed of a sheet-like body made up of a positive electrode, a negative electrode, and a separator that insulates them, all stacked together. There are two types of structures for energy storage elements: a jelly roll type in which the sheet-like body is wound into a roll, and a stack type in which multiple sheet-like bodies are stacked together. Among the stack type energy storage elements, there are mainly two types: a double-tab structure in which a positive electrode tab (positive electrode terminal) and a negative electrode tab (negative electrode terminal) are provided on opposite sides of the sheet-like body, and a single-tab structure in which a positive electrode tab and a negative electrode tab are provided on the same side of the sheet-like body. Furthermore, energy storage elements can be two-terminal elements in which one positive electrode tab and one negative electrode tab are shared for charging and discharging, or elements that have separate positive electrode tabs for charging and positive electrode tabs for discharging. In particular, elements that have two positive electrode tabs for charging and discharging, and one negative electrode tab shared for charging and discharging, will be called three-terminal elements. In the first embodiment, the case in which a two-terminal element is used will be described.

[0019] Figure 2 illustrates the charging and discharging operations of two-terminal elements. Figure 2(a) shows the charging operation of a two-terminal element 20A with a tab structure on both sides, Figure 2(b) shows its discharging operation, Figure 2(c) shows the charging operation of a two-terminal element 20B with a tab structure on one side, and Figure 2(d) shows its discharging operation.

[0020] In the case of a two-terminal element 20A with a tab structure on both sides, during charging, as shown in Figure 2(a), lithium ions (Li in the figure) + The lithium ions move through the active material layer from the positive electrode to the negative electrode. Also, during discharge, as shown in Figure 2(b), lithium ions move through the active material layer from the negative electrode to the positive electrode.

[0021] On the other hand, in the case of the two-terminal element 20B with a tab structure on one side, during charging, as shown in Figure 2(c), lithium ions move from the positive electrode to the negative electrode within the active material layer, and lithium ions also reciprocate within the active material layer. During discharge, as shown in Figure 2(d), lithium ions move from the negative electrode to the positive electrode within the active material layer, and lithium ions also reciprocate within the active material layer.

[0022] Thus, although the structure of the active material layer is the same in both the double-tab structure and the single-tab structure, the movement of lithium ions differs depending on the position of the electrodes. In the double-tab structure, the movement of lithium ions is relatively uniform, but because of the distance between the positive and negative electrodes, the distance traveled by lithium ions is long.

[0023] On the other hand, in a single-tab structure, the lithium ions travel a short distance at the start of charging and discharging, allowing for high-current discharge with low resistance. However, as the available lithium ions gradually spread further, the resistance gradually increases. Furthermore, repeated charging and discharging can lead to an uneven distribution of lithium ions.

[0024] Figure 3 shows the electrons of a two-terminal element 20A with a tab structure on both sides (e in the figure). - ) and lithium ions (Li in the diagram) + This is a diagram illustrating the movement of the battery. Figure 3(a) shows the case of charging, and Figure 3(b) shows the case of discharging.

[0025] The two-terminal element 20A comprises a positive electrode composed of a positive electrode current collector 21 and a positive electrode side active material layer 22 formed on the surface of the positive electrode current collector 21, a negative electrode composed of a negative electrode current collector 25 and a negative electrode side active material layer 24 formed on the surface of the negative electrode current collector 25, and a separator 23 that separates the positive electrode side active material layer 22 and the negative electrode side active material layer 24.

[0026] In the case of a two-terminal element 20A with a tab structure on both sides, during charging, electrons are injected from the negative tab side of the negative electrode current collector 25 (right side in Figure 3(a)) and emitted from the positive tab side of the positive electrode current collector 21 (left side in Figure 3(a)). During discharge, electrons are injected from the positive tab side of the positive electrode current collector 21 (left side in Figure 3(b)) and emitted from the negative tab side of the negative electrode current collector 25 (right side in Figure 3(b)).

[0027] In a double-tab structure, as shown in Figures 3(a) and (b), a lithium ion diffusion section 26 exists between the positive and negative electrode tabs. Since lithium ions move through this diffusion section 26, the resistance at the start of charging and discharging increases as the lithium ion movement speed increases.

[0028] Figure 4 shows the electrons of a two-terminal element 20B with a tab structure on one side (e in the figure). - ) and lithium ions (Li in the diagram) + This diagram illustrates the movement of the battery. Figure 4(a) shows the case of charging, and Figure 4(b) shows the case of discharging.

[0029] In the case of the two-terminal element 20B with a tab structure on one side, during charging, electrons are injected from the negative tab side of the negative electrode current collector 25 (left side in the case of Figure 4(a)), and electrons are emitted from the positive tab side of the positive electrode current collector 21 (left side in the case of Figure 4(a)). During discharge, electrons are injected from the positive tab side of the positive electrode current collector 21 (left side in the case of Figure 4(b)), and electrons are emitted from the negative tab side of the negative electrode current collector 25 (left side in the case of Figure 4(b)).

[0030] In a single-tab structure, as shown in Figure 4, the positive and negative electrode tabs are located close together, resulting in faster lithium ion movement at the start of charging and discharging, enabling high input / output. However, the lithium ion diffusion region 26 is not located between the positive and negative electrode tabs but far from both tabs, and therefore does not contribute to the diffusion of lithium ions that affects charging and discharging. As a result, lithium ion movement gradually slows down, and the charge / discharge rate decreases over time. Furthermore, lithium ion movement tends to be more frequent in areas close to both tabs, making it prone to non-uniformity.

[0031] Figure 5 illustrates the configuration of a storage battery 1 using a two-terminal element 20. The two-terminal element 20 in the figure may be either a two-terminal element 20A with tabs on both sides or a two-terminal element 20B with tabs on one side.

[0032] When the storage battery 1 is constructed using two-terminal elements 20, both the single-tab structure and the double-tab structure involve connecting the two-terminal elements 20 in series, as shown in Figure 5. This allows for the construction of a storage battery 1 where the sum of the cell voltages of the two-terminal elements 20 is the battery voltage. In the configuration shown in Figure 5, the charging input and the load output are directly connected, so the input voltage affects the output voltage, and conversely, the output voltage affects the input voltage.

[0033] In conventional "chemical batteries" that utilize chemical reactions, the hysteresis of the polarization reaction causes the voltage for charging and the voltage for discharging to be different from each other.

[0034] In direct charging, the panel voltage is fixed by the battery voltage (normally the discharge voltage), so it is necessary to choose whether to charge or discharge. In order to build a system that passes through only the amount used as a load and charges only the excess, the charging voltage and discharge voltage of battery 1 must be equal.

[0035] Lithium-ion batteries that utilize the intercalation phenomenon rather than electrochemical reactions that create polarization potential during charging and discharging achieve these characteristics and are therefore suitable for application to the storage and discharging system 100 shown in Figure 1.

[0036] Figure 6 is a block diagram illustrating a storage and discharge system 600 according to a first comparative example to this embodiment.

[0037] The storage and discharging system 600 includes a storage battery 6, one or more solar panels 2A (solar generators), a charge / discharge controller 7, and a power controller that combines a DC / AC inverter 8a and an MPPT circuit 8b.

[0038] When converting solar energy into electricity, the amount of electricity that can be extracted is expressed as P = IV. While the current and voltage of the solar panel 2A vary depending on its state, the role of the MPPT circuit 8b is to maximize this power P.

[0039] The MPPT circuit 8b continuously changes the voltage of the solar panel 2A and searches for the point where the product of the changing current and voltage is maximum.

[0040] The charge / discharge controller 7 is connected to the DC / AC inverter 8a and controls the charging and discharging of the battery 6.

[0041] In the storage and discharge system 600, the output of the 2A solar panel is converted to a 100V AC voltage by the power controller. This 100V AC voltage is then converted to a DC voltage through AC / DC conversion and used to charge the battery 6. Conversely, the DC voltage discharged from the battery 6 is converted back to a 100V AC voltage and returned to the power controller.

[0042] Figure 7 is a block diagram illustrating a storage and discharge system 700 according to a second comparative example to this embodiment.

[0043] The storage and discharge system 700 comprises a storage battery 6, one or more solar panels 2A, a charge / discharge controller 7, and a power controller that combines a DC / AC inverter 8a and an MPPT circuit 8b.

[0044] The battery storage and discharge system 700 is an efficiency-improving system known as the multi-DC link type. The DC voltage output from the MPPT circuit 8b is directly used to charge the battery 6, and the DC voltage discharged from the battery 6 is returned to the MPPT bus and output via the DC / AC inverter 8a.

[0045] The 700 energy storage / discharge system tends to have a higher power generation rate per unit of solar radiation, i.e., a higher power generation efficiency, compared to the 600 energy storage / discharge system. Furthermore, while the 600 energy storage / discharge system often experiences a phenomenon called recombination, where power generation and efficiency fluctuate when solar radiation and temperature are high, this recombination is less likely to occur in the 700 energy storage / discharge system.

[0046] In the case of the storage / discharge system 600, the current from the MPPT circuit 8b is detected, the insufficient power is requested from the battery 6, and after DC / AC → AC / DC → DC / DC conversion, it is necessary to mix and then perform further DC / AC conversion. In the case of the storage / discharge system 700, the insufficient power from the MPPT circuit 8b is requested from the battery 6, and the insufficient power is supplied to the DC / AC inverter 8a through a DC / DC converter (not shown). In either case, monitoring of the current and management of charging and discharging of the battery 1 are necessary, but according to the storage / discharge system 100 shown in Figure 1, since the panel voltage is fixed to the battery voltage, charging and discharging of the battery 1 automatically switches according to the required current, enabling efficient operation without the need for DC / DC conversion.

[0047] Since solar panel 2A is composed of semiconductor elements, the resistance of the elements decreases as the temperature rises. On the other hand, electronic circuits such as MPPT circuit 8b are placed in the shade, so their internal resistance does not change. Alternatively, since the resistance of the conductors included in MPPT circuit 8b increases with temperature, as the temperature of solar panel 2A rises, the resistance of solar panel 2A decreases, while the circuit resistance of MPPT circuit 8b remains unchanged or increases.

[0048] When sunlight is strong, the voltage of solar panel 2A decreases and the current increases. However, when the resistance of solar panel 2A decreases and the circuit resistance is high, it becomes easier for the current to be converted into "heat" within solar panel 2A than for it to flow out as current, thus reducing the amount of current. This is the "recombination" mentioned earlier, but lithium-ion batteries have lower internal resistance compared to many chemical batteries. Manganese-based lithium-ion batteries, in particular, have low internal resistance, and even when solar panel 2A becomes hot and its resistance decreases, it can maintain even lower resistance, making it possible to maintain the power generation efficiency of solar panel 2A even when exposed to strong light at high temperatures.

[0049] [2. Second Embodiment] In addition to the two-terminal element 20 described in the first embodiment, the storage battery can also be composed of a three-terminal element or a four-terminal element. Therefore, in the second embodiment, a storage and discharge system using a three-terminal element will be described. Note that this embodiment is also applicable to a four-terminal element.

[0050] The energy storage element described in Patent Document 2 comprises a positive electrode, a negative electrode, a separator, and first to third terminals. The first terminal is a charging terminal (tab) connected to the outer circumference of the positive electrode current collector, the second terminal is connected to the outer circumference of the negative electrode current collector and is used for at least one of charging and discharging, and the third terminal is a discharge terminal connected to the outer circumference of one of the positive electrode current collector and the negative electrode current collector at a distance from the first or second terminal.

[0051] When using a two-terminal element, the amount of current changes depending on the load size. As the load (current) increases, the panel voltage rises, and the current decreases accordingly. On the other hand, when using a three-terminal element, the battery and the load are disconnected, and the battery and the solar panel are disconnected. Therefore, even if the load (current) increases, the relationship between the battery voltage and the panel voltage does not change, thus preventing a decrease in current.

[0052] Figure 8 illustrates the effect of the output voltage of the solar panel 2A on the storage and discharge system. Figure 8(a) shows the case of a storage and discharge system 100 using a two-terminal element 20 according to the first embodiment, and Figure 8(b) shows the case of a storage and discharge system 200 using a three-terminal element 30 according to this embodiment.

[0053] When using a battery 1 with a two-terminal element 20, even if the battery voltage is constant, the battery 1 is essentially connected to the circuit, so if the voltage or resistance of the load changes, it may affect the voltage of the solar panel 2A.

[0054] On the other hand, when using a battery 1 with a three-terminal element 30, the input terminal of the three-terminal element 30 is connected in parallel to the solar panel 2A, and the output terminal is connected to the DC / AC inverter 4. In this configuration, the circuit of the solar panel 2A and the battery 1 is disconnected, and the circuit of the battery 1 and the DC / AC inverter 4 are disconnected.

[0055] As an effect, current fluctuations, current and voltage noise that may occur when the two-terminal elements 20 connect the battery 1 in parallel are absorbed. Also, when the current demanded from the DC / AC inverter 4 exceeds the current from the solar panel 2A, the terminal voltage of the battery 1 decreases. However, because the three-terminal elements 30 separate the input circuit (connection to the solar panel 2A) and the output circuit (connection to the DC / AC inverter 4), the battery voltage becomes the reference, and the panel voltage becomes battery voltage + cable resistance × current, and the voltage to the DC / AC inverter 4 becomes battery voltage - cable resistance × current. As a result, the overall voltage of the storage and discharge system 200 becomes high, thus increasing the power generation efficiency itself.

[0056] Next, an example configuration of the three-terminal element 30 will be described. Figure 9 is a diagram illustrating the first configuration (30A) of the three-terminal element 30.

[0057] The three-terminal element 30, like the two-terminal element 20, is composed of a positive electrode (first electrode) having a positive electrode current collector 31 (first polarity current collector) and an active material layer 32 formed on the surface of the positive electrode current collector 31 (first polarity current collector), a negative electrode (second electrode) having a negative electrode current collector 35 (second polarity current collector) and an active material layer 34 formed on the surface of the negative electrode current collector 35 (second polarity current collector), and a separator 33 sandwiched between the positive electrode and the negative electrode. Furthermore, the three-terminal element 30 includes a positive electrode tab 31' (first terminal) for charging connected to a positive electrode current collector 31 (first polarity current collector), a negative electrode tab 35' (second terminal) for both charging and discharging connected to a negative electrode current collector 35 (second polarity current collector), and a positive electrode tab 31' (third terminal) for discharging, which is connected to the positive electrode current collector 31 (first polarity current collector) and separated from the positive electrode tab 31' (first terminal) for charging.

[0058] Alternatively, instead of the shared negative electrode tab 35' (second terminal) used for both charging and discharging, a charging negative electrode tab (second terminal) connected to a negative electrode current collector (second polarity current collector) and a discharge negative electrode tab (fourth terminal) separate from this negative electrode tab (second terminal) may be provided, resulting in a four-terminal element. Also, although four positive electrode tabs 31' are shown in Figure 9, these are examples of the arrangement of positive electrode tabs 31', and in reality, only two positive electrode tabs 31' are needed.

[0059] Furthermore, in the case of the three-terminal element 30A shown in Figure 9, the longer of the distance between the positive electrode tab 31' (first terminal) and the negative electrode tab 35' (second terminal) for charging, and the distance between the positive electrode tab 31' (third terminal) and the negative electrode tab 35' for discharging, is L. P-N The distance between the positive electrode tabs 31′ is L P-P The maximum current supplied by the 2A solar panel (power generation unit) is I INMAX The rated input current of battery 1 is I BR If we define them as such, then the following equation 1 is also acceptable.

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[0060] Note that Equation 1 can also be applied to a four-terminal element having two negative electrode tabs, one for charging and one for discharging. In this case, the greater of the distance between the charging positive electrode tab (terminal 1) and the charging negative electrode tab (terminal 2) and the distance between the discharging positive electrode tab (terminal 3) and the discharging negative electrode tab (terminal 4) is L. P-N That's how you should define it.

[0061] The relationship between the noise of the output power of the solar panel 2A and the capacity of the storage battery 1 is complex, but when using a three-terminal element 30A that meets the above equation 1, a higher noise filtering effect can be expected.

[0062] Figure 10 is an example of the second configuration (30B, 30C) of the three-terminal element 30, and Figure 11 is a diagram showing the configurations of three-terminal elements 30D, 30E, which are comparative examples of three-terminal elements 30B, 30C.

[0063] In the case of the comparative example three-terminal elements 30D and 30E, as shown in Figures 11(a) and (b), two positive electrode tabs 31' are provided at the end of the positive electrode current collector 31, and one negative electrode tab 35' is provided at the end of the negative electrode current collector 35. In the comparative example, a bypass circuit is formed between the two positive electrode tabs 31' that passes through the uncoated portion of the active material, rather than through the active material layers 32 and 34.

[0064] On the other hand, as shown in Figures 10(a) and (b), the three-terminal elements 30B and 30C also have two positive electrode tabs 31' on the positive electrode current collector 31, similar to the comparative example. However, in the positive electrode (first electrode), at least active material layers 32 and 34 are formed on the paths between the two positive electrode tabs 31' (first terminal and third terminal).

[0065] Specifically, in the case of the three-terminal element 30B, similar to the three-terminal elements 30D and 30E of the comparative examples, it has two positive electrode tabs 31' provided on the positive electrode current collector 31 and a negative electrode tab 35' provided on the negative electrode current collector 35, and both positive electrode tabs 31' are positioned with the active material layers 32 and 34 in between the negative electrode tabs 35'. However, unlike the configuration of the comparative examples, in the three-terminal element 30B, a notch 31a leading to the active material layers 32 and 34 is formed in the portion of the positive electrode current collector 31 located between the two positive electrode tabs 31', so that the active material layers 32 and 34 are always interposed between the two positive electrode tabs 31'.

[0066] In the case of the three-terminal element 30C, the two positive electrode tabs 31' provided on the positive electrode current collector 31 are arranged with the active material layers 32 and 34 in between. In this case as well, as shown in Figure 10(a), the active material layers 32 and 34 are always interposed between the two positive electrode tabs 31'.

[0067] Figure 12 shows the electrons in the three-terminal element 30B having the second configuration (e in the figure). - ) and lithium ions (Li in the diagram) + This is a diagram illustrating the movement of the ) component. The same applies to the three-terminal element 30C.

[0068] The three-terminal element 30B is divided into a charging section 37 located on the side where electrons flow in at the negative electrode current collector 35 and on the side where electrons flow out at the positive electrode current collector 31, a discharge section 38 located on the side where electrons flow in at the positive electrode current collector 31 and on the side where electrons flow out at the negative electrode current collector 35, and a diffusion section 36 located between the charging section 37 and the discharge section 38. Of these, the charging section 37 is the region where lithium ions move from the active material layer 32 on the positive electrode side to the active material layer 34 on the negative electrode side during charging. The discharge section 38 is the region where lithium ions move from the active material layer 34 on the negative electrode side to the active material layer 32 on the positive electrode side during discharge. This is the same for the four-terminal element.

[0069] To express the above generally, including the four-terminal element, the active material layers of the positive electrode (first electrode) and negative electrode (second electrode) can be said to have a charging section 37 which is a path between the positive electrode tab (first terminal) and the negative electrode tab (second terminal) for charging, a discharge section 38 which is a path between the positive electrode tab (third terminal) and the negative electrode tab (fourth terminal) for discharging, and a diffusion section 36 which diffuses lithium ions and separates the charging section 37 and the discharge section 38.

[0070] In the case of the two-terminal element 20, the input terminal and output terminal are connected to the same positive tab. In this case, there is a connection circuit via the tab and a connection circuit that passes through the portion coated with the active material. While the portion coated with the active material, i.e., the diffusion portion 26, has a constant voltage depending on the distribution amount of lithium ions, the uncoated portion is positioned closer to the input and output terminals. Therefore, when the output current is greater than the input current, the terminal voltage drops below the voltage of the diffusion portion 26. This is because the uncoated portion acts as a bypass, causing a voltage drop.

[0071] In contrast, in the case of the three-terminal element 30B, the circuit connection always passes through the diffusion section 36, so both the input and output terminals have the voltage of the diffusion section 36. At the input, electrons move to the diffusion section 36 due to the slightly higher generated voltage due to the circuit resistance compared to the voltage of the diffusion section 36, and at the output, electrons flow to the load as the voltage of the diffusion section 36 is used as a reference, and the voltage drops due to the circuit resistance.

[0072] As a result, in the case of the two-terminal element 20, a bypass exists that directly connects the power generation and the load. Therefore, a voltage drop occurs in proportion to the current due to the circuit resistance from the solar panel 2A to the load. In contrast, in the case of the three-terminal element 30B, the voltage change due to the resistance from the solar panel 2A to the three-terminal element 30B is a voltage that corresponds to the current, with the voltage of the diffusion section 36 as the reference. On the other hand, on the load side, a voltage drop occurs due to the circuit resistance from the three-terminal element 30B to the load, with the voltage of the diffusion section 36 as the reference. As a result, it becomes possible to control the voltage to a high level regardless of load fluctuations, and the power generation energy increases compared to the two-terminal element 20.

[0073] Furthermore, in the case of the three-terminal elements 30D and 30E in the comparative example, as described above, although the positive electrode tabs 31' are separated for charging and discharging, there is an uncoated area of ​​active material between the two positive electrode tabs 31'. Since this uncoated area acts as a bypass between the two positive electrode tabs 31', it is affected by the voltage drop from the load.

[0074] Figure 13 shows an example configuration of a storage battery 1 using a three-terminal element 30. The three-terminal element 30 in the figure is one of the three-terminal elements 30A to 30C.

[0075] The battery 1 shown in Figure 13 consists of a three-terminal element 30 and multiple two-terminal elements 20 connected in series to the charging section 37, diffusion section 36, and discharge section 38 of the three-terminal element 30. The three-terminal element 30 is used for input and output. The two-terminal elements 20 connected in series are used for voltage adjustment to increase the voltage. Note that in Figure 13, the same position in the lateral direction indicates equal voltage.

[0076] In Figure 13, the charging section 37, the diffusion section 36, and the discharge section 38 are shown as being of the same size, but in reality, the charging section 37 and the discharge section 38 are very narrow regions near the positive or negative electrode tab. The diffusion section 36 is overwhelmingly large, and lithium ions (Li in Figure 12) +Diffusion occurs between and within the electrodes, and as a result, the voltage is determined by the state of lithium ions within the electrodes. The charging section 37 and the discharging section 38 have the same voltage as the overwhelmingly large diffusion section 36. In terms of equivalent circuitry, the charging section 37, diffusion section 36, and discharging section 38 are connected by a conductor (current collector), so they are affected by the voltage of the discharging section 38, but in reality, the voltage is fixed by the voltage of the diffusion section 36.

[0077] This function allows the solar panel 2A, which is the power generation unit, to accept voltage noise from the charging unit 37 as current regardless of the voltage, and to transmit electrons to the diffusion unit 36 ​​(e in Figure 12). - The noise is transmitted in the form of movement, and can be extracted from the output section as a current of a constant voltage. However, when the input terminal and output terminal are electrically connected by the two-terminal element 20, some of the noise that enters the solar panel 2A is absorbed by the diffusion section 26, but the portion proportionally distributed by the internal resistance is output as noise from the discharge section 28.

[0078] Figure 14 shows another example of a battery 1 configuration using a three-terminal element 30. The three-terminal element 30 in the figure is one of the three-terminal elements 30A to 30C.

[0079] In the case of Figure 14, the storage battery 1 has a charging section 37, a diffusion section 36, and a discharge section 38 that are electrically connected within a three-terminal element 30, and the diffusion section 36 is configured by connecting multiple two-terminal elements 20 in series. Since the negative electrodes of the charging section 37, diffusion section 36, and discharge section 38 are common, a high-voltage device can be realized by connecting two-terminal elements 20 in series to them as needed.

[0080] Furthermore, to increase capacity, a system capable of high-current discharge can be constructed by connecting two-terminal elements 20, including the three-terminal element 30, in series with voltage-matching elements, and connecting a discharge-type positive electrode tab to the positive electrode with the highest voltage, thereby absorbing input noise and increasing the number of storage batteries 1 in parallel. In the case of Figure 14, the two-terminal element 20 is connected to the diffusion part 36 of the three-terminal element 30, but this embodiment is not limited to this, and the two-terminal element 20 may also be connected to the charging part 37 or the discharge part 38.

[0081] [3. Third Embodiment] In the first and second embodiments, storage and discharge systems 100 and 200 using a solar panel 2A as the power generation unit were described. In the third embodiment, an example is described in which a different power generation unit is applied to a system similar to these storage and discharge systems 100 and 200.

[0082] Figure 15 is a block diagram illustrating a storage and discharge system 300 equipped with a wind turbine (wind turbine 2B).

[0083] The storage and discharge system 300 is an example in which a wind turbine is used instead of the solar power generator in the storage and discharge system 100. Wind power generation by wind turbine 2B (power source) is an AC power source in which the voltage and current change depending on the rotation speed. Therefore, in the case of the storage and discharge system 300, a diode bridge 5 (AC-DC converter) that converts AC power to DC power is provided on the output side of wind turbine 2B. By connecting the storage battery 1 in parallel with the output of this diode bridge 5, the storage battery 1 can be charged.

[0084] In the storage and discharge system 300, similar to the power generation by solar panel 2A, the battery voltage fixes the output voltage of diode bridge 5, thereby fixing the voltage of the wind turbine (wind turbine 2B). When the voltage of the wind turbine is fixed, the rotational speed is fixed, and the energy from the wind flow is converted into electric current, similar to the power generation by solar panel 2A.

[0085] By using a three-terminal element 30 in the battery 1, the input circuit and output circuit are separated, so spikes (current and voltage fluctuations) caused by wind speed fluctuations (such as gusts) are absorbed, and the DC / AC inverter side is not affected. Therefore, the noise filter that was conventionally required, expensive, and caused a decrease in efficiency becomes unnecessary. In addition, since the generated energy can be stored or discharged without loss, maximum efficiency can be achieved.

[0086] Figure 16 is a block diagram illustrating a storage and discharge system 400 equipped with multiple wind turbines (wind turbines 2B).

[0087] The energy storage and discharging system 400 includes a power generation unit configured by connecting a combination of a wind turbine 2B and a diode bridge 5 connected to the output of the wind turbine 2B in parallel. The energy storage and discharging system 400 also includes a battery 1 connected in parallel to each diode bridge 5. In this configuration, each wind turbine 2B can be controlled by the voltage of a common battery 1, so power generation and storage can be performed without the use of a control circuit.

[0088] In wind turbine systems, it has traditionally been said that the cost of the wind turbine control circuits, such as over-rotation control circuits and pulse power generation control circuits, or the noise filter circuits that absorb the generated noise, is higher than the cost of the wind turbine 2B itself. However, with the 400 energy storage and discharge system, multiple wind turbines 2B can be managed and stored using only the energy storage circuit, making significant cost reductions possible.

[0089] Figure 17 is a block diagram illustrating a storage and discharge system 500 equipped with a solar power generator (solar panel 2A), a wind power generator (wind turbine 2B), and a hydroelectric power generator (water turbine 2C).

[0090] The 500 storage and discharge system is a combined power generation system that utilizes solar, wind, and hydroelectric power.

[0091] Solar power generation differs from wind and hydroelectric power generation in that they use either direct current (DC) or alternating current (AC), and the power generation management parameters themselves are also different. Therefore, each type of power generation was converted to DC for storage and discharge.

[0092] In this respect, in the case of the storage and discharge system 500, the voltage of the storage battery 1 controls solar power generation, wind power generation, and hydroelectric power generation respectively, so the difference between DC and AC power generation is not an issue, and the storage battery 1 itself controls the power generation. Therefore, by optimizing the voltage setting, combined power generation can be easily achieved. The power charged in the storage battery 1 corresponding to the solar panel 2A, wind turbine 2B, and hydroelectric turbine 2C may be discharged and charged into a common main battery 9.

[0093] Since battery 1 can discharge high currents, it is possible to create an EV station that uses renewable energy to store electricity in battery 1 and rapidly charge EV vehicles in locations where solar, wind, or hydroelectric power generation is available. It can also be used as emergency power during disasters.

[0094] [4. Effects] The disclosed storage and discharge system and energy storage element make it possible to realize a storage and discharge system that can generate stable power with high efficiency.

[0095] [5. Others] The embodiments described above have focused on solar power generation, wind power generation, and hydroelectric power generation, but are not limited to these. The storage battery 1 and storage / discharge systems 100, 200, 300, 400, and 500 in the embodiments described above can be used to stabilize the power generated by any power generation system, including general dynamos, geothermal power generation, and waste heat power generation.

[0096] In the embodiments described above, the storage battery 1 was given as a lithium-ion secondary battery or a manganese-based lithium-ion secondary battery, but it is not limited to these. The storage battery 1 may be, for example, a sodium-ion secondary battery or a magnesium-ion secondary battery. [Explanation of Symbols]

[0097] 1: Storage battery 2A: Solar panels (solar power generators) 2B: Windmill (wind turbine) 2C: Water turbine (hydroelectric generator) 3: D-CS (Direct-Charge System) 4: DC / AC Inverter 5: Diode Bridge 6: Storage batteries 7: Charge / Discharge Controller 8a: DC / AC inverter 8b :MPPT (Maximum Power Point Tracking) circuit 9: Main battery 20, 20A, 20B: Two-terminal elements 30, 30A, 30B, 30C: Three-terminal elements 21, 31: Positive electrode current collector 22, 32: Positive electrode side active material layer 23, 33: Separator 24, 34: Negative electrode side active material layer 25, 35: Negative electrode current collector 26, 36: Diffusion section 31a: Notch 31′: Positive tab (positive terminal) 35′: Negative tab (negative terminal) 37: Live part 38:Discharge part 100, 200, 300, 400, 500: Storage and Discharge System

Claims

1. A storage element that constitutes a battery capable of charging DC power supplied from a power generation unit, A first electrode having a first polar current collector and an active material layer formed on the surface of the first polar current collector, A second electrode having a second polarity current collector and an active material layer formed on the surface of the second polarity current collector, A separator sandwiched between the first electrode and the second electrode, A first charging terminal connected to the first polarity current collector, A second charging terminal connected to the aforementioned second polarity current collector, A third discharge terminal connected to the first polarity current collector and separated from the first terminal, It comprises a fourth terminal connected to the second polarity current collector and identical to or separate from the second terminal, The maximum current supplied by the power generation unit is I ＩＮＭＡＸ The rated input current of the storage battery is I ＢＲ The longer of the distance between the first and second terminals and the distance between the third and fourth terminals is L. Ｐ－Ｎ The distance between the first terminal and the third terminal is L. Ｐ－Ｐ If defined as such, then equation 1 follows. A storage element characterized by the following features. [Math 1]

2. The first electrode has at least the active material layer formed on the path between the first terminal and the third terminal. The energy storage element according to claim 1, characterized in that it is a feature of the present invention.

3. The active material layer of each of the first electrode and the second electrode is A charging section which forms a path between the first terminal and the second terminal, A discharge section which forms a path between the third terminal and the fourth terminal, A diffusion section separates the charging section and the discharging section, as lithium ions diffuse. The energy storage element according to claim 1 or 2, characterized by having the following features.

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