Power supply device

Abstract

To provide a power supply device that prevents a chain reaction of gas ejection caused by an increase in the pressure inside an adjacent storage battery even when the pressure inside a first storage battery increases and gas ejects from a valve.SOLUTION: A power supply device includes a first storage battery which is a lithium ion battery containing a nickel-cobalt-manganese based positive electrode active material, a second storage battery which is a lithium ion battery containing an iron phosphate based positive electrode active material, and a case that houses the first storage battery and the second storage battery, the case includes a plurality of attachments therein, the first storage battery and the second storage battery are respectively placed on the attachments, adjacent first storage batteries, adjacent second storage batteries, and the adjacent first and second storage batteries are all arranged at a distance from each other, the first storage battery includes a valve that opens when the pressure inside the first storage battery rises to release internal gas, and the gas is released from the valve in the direction of the second storage battery or in the direction of the wall of the case.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power supply device. [Background technology]

[0002] Conventionally, power supply devices have been used that house two or more different types of storage batteries inside a single housing.

[0003] For example, Patent Document 1 discloses a battery pack including a battery pack case and battery cells housed in the battery pack case, the internal space of the battery pack case being composed of a first region and a second region, the first battery cell being arranged in the first region and the second battery cell being arranged in the second region, the second battery cell being arranged surrounding the periphery of the first battery cell, the first battery cell and the second battery cell having a first discharge voltage platform and a second discharge voltage platform, respectively, the average discharge voltage of the first discharge voltage platform being higher than the average discharge voltage of the second discharge voltage platform, and when the sum of the discharge capacities corresponding to the first discharge voltage platform and the second discharge voltage platform is 100% for each of the first battery cell and the second battery cell, the discharge capacity percentage corresponding to the second discharge voltage platform of the second battery cell is larger than the discharge capacity percentage corresponding to the second discharge voltage platform of the first battery cell. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-547579 Summary of the Invention [Problem to be solved by the invention]

[0005] In a conventional power supply device containing multiple storage batteries, if an abnormality occurs in one storage battery and the internal pressure rises, high-temperature gas is ejected from the valve. If this gas is ejected toward an adjacent storage battery, the adjacent storage battery is also heated, causing the internal pressure to rise, leading to a chain reaction of high-temperature gas being ejected from the adjacent storage battery. In this way, when an abnormality occurs in one storage battery within the power supply device, high-temperature gas can be ejected from multiple storage batteries in a chain reaction.

[0006] The present disclosure aims to provide a power supply device that prevents a chain reaction of gas emissions due to an increase in pressure inside an adjacent storage battery even if the pressure inside a first storage battery increases and gas is released from a valve. [Means for solving the problem]

[0007] Means for solving the above problems include the following aspects. <1> one or more first storage batteries that are lithium-ion batteries containing a nickel-cobalt-manganese based positive electrode active material; one or more second storage batteries that are lithium-ion batteries containing an iron phosphate-based positive electrode active material; a housing that houses the first storage battery and the second storage battery, The housing has a plurality of attachments therein, the first storage battery and the second storage battery are each placed on the attachment; adjacent first storage batteries, adjacent second storage batteries, and adjacent first and second storage batteries are all arranged apart from each other; the first storage battery has a valve that opens when the internal pressure of the first storage battery increases to release internal gas, The gas is ejected from the valve toward the second storage battery or toward a wall of the housing. [Effects of the Invention]

[0008] According to the present disclosure, a power supply device is provided that, even if the pressure inside a first storage battery rises and gas is released from a valve, prevents the pressure inside an adjacent storage battery from rising and causing a chain reaction of gas release. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of a power supply device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Power supply> A power supply device according to an embodiment of the present disclosure includes one or more first storage batteries that are lithium ion batteries containing a nickel-cobalt-manganese based positive electrode active material, one or more second storage batteries that are lithium ion batteries containing an iron phosphate based positive electrode active material, and a housing that houses the first storage batteries and the second storage batteries. The housing has a plurality of attachments inside, and the first storage battery and the second storage battery are placed on the attachments. Adjacent first storage batteries, adjacent second storage batteries, and adjacent first and second storage batteries are all spaced apart from each other. The first storage battery has a valve that opens when the internal pressure of the first storage battery increases to release the internal gas. The gas ejected from the valve is ejected from the valve toward the second storage battery or toward the wall of the housing.

[0011] By having the above-mentioned configuration, the power supply device according to an embodiment of the present disclosure is able to prevent a chain reaction of gas ejection due to an increase in pressure inside an adjacent storage battery, even if the pressure inside a first storage battery rises and gas is ejected from the valve.

[0012] Conventionally, power supplies containing two or more different types of storage batteries housed within a single housing have been used. In such power supplies, if an abnormality occurs in one storage battery and the internal pressure rises, high-temperature gas is ejected from a valve. Furthermore, if this gas is ejected toward an adjacent storage battery, the adjacent storage battery also heats up, causing the internal pressure to rise, leading to a chain reaction of high-temperature gas being ejected from the adjacent storage battery. In other words, gas ejected from one storage battery can cause further gas to be generated from the adjacent storage battery on the opposite side, and so on. In this way, when an abnormality occurs in one storage battery within a power supply unit, high-temperature gas can be ejected from multiple storage batteries.

[0013] In contrast, a power supply device according to an embodiment of the present disclosure includes a first storage battery that is a lithium-ion battery containing a nickel-cobalt-manganese positive electrode active material, and a second storage battery that is a lithium-ion battery containing an iron phosphate positive electrode active material. When an abnormality occurs in the storage batteries, the temperature of the gas expelled from the valve due to an increase in internal pressure is relatively lower in the second storage battery containing an iron phosphate positive electrode active material than in the first storage battery containing a nickel-cobalt-manganese positive electrode active material. Furthermore, the second storage battery containing an iron phosphate positive electrode active material is less likely to generate abnormal heat at a high state of charge (SOC).

[0014] In the present disclosure, when the internal pressure of the first storage battery increases, gas is ejected from the valve either toward the second storage battery or toward the wall of the housing. When gas from the first storage battery is ejected toward the second storage battery, the second storage battery, which contains an iron phosphate-based positive electrode active material, is less likely to generate abnormal heat, thereby preventing a chain reaction of pressure increase within the second storage battery and gas ejection from the second storage battery. Furthermore, when gas from the first storage battery is ejected toward the wall of the housing, heating of other storage batteries by the gas is prevented, preventing a chain reaction of gas ejection from the other storage batteries. Therefore, even if the internal pressure of the first storage battery increases and gas is ejected from the valve, a chain reaction of pressure increase within adjacent storage batteries and gas ejection is prevented. In other words, a chain reaction of temperature increase and gas ejection throughout the power supply device is prevented.

[0015] In particular, in the case of a power supply device that uses a reused battery for at least one of the first and second storage batteries, it is conceivable that multiple types of storage batteries with different thermal stability will be mixed. However, even when some of the batteries are reused, the power supply device according to the embodiment of the present disclosure can suppress chain reaction temperature increases and gas emissions throughout the power supply device.

[0016] Next, a specific configuration of the power supply device according to the embodiment of the present disclosure will be described.

[0017] Fig. 1 is a schematic cross-sectional view showing an example of a power supply device according to an embodiment of the present disclosure. The power supply device 10 shown in Fig. 1 includes a housing 4, first storage batteries 1A-1D that are lithium-ion batteries containing a nickel-cobalt-manganese-based positive electrode active material, and second storage batteries 2A-2E that are lithium-ion batteries containing an iron phosphate-based positive electrode active material. The housing 4 includes a plurality of attachments (not shown) therein, and the first storage batteries 1A-1D and second storage batteries 2A-2E are respectively placed on the attachments. Each of the first storage batteries 1A-1D and second storage batteries 2A-2E has a valve (not shown) that opens when the internal pressure increases to release internal gas.

[0018] The power supply device 10 has a plurality (four in FIG. 1) of first storage batteries 1A-1D and a plurality (five in FIG. 1) of second storage batteries 2A-2E. Adjacent storage batteries (the first storage batteries 1A-1D and the second storage batteries 2A-2E) are arranged at a distance from each other. In the power supply device 10, the first storage batteries 1A-1D are stacked so that they are not arranged adjacent to each other. That is, in the power supply device 10, the first storage battery 1A, the second storage battery 2A, the first storage battery 1B, the second storage battery 2B, the first storage battery 1C, the second storage battery 2C, the first storage battery 1D, the second storage battery 2D, and the second storage battery 2E are stacked in this order from one side (the upper side in FIG. 1) in the stacking direction of the storage batteries, and the first storage batteries 1A-1D are not arranged adjacent to each other.

[0019] By arranging the first storage batteries 1A-1D so that they are not adjacent to each other, even if the internal pressure of a first storage battery increases and gas is released from the valve, the gas can be released from the valve toward the second storage battery or toward the wall of the housing. For example, consider a case where the internal pressure of storage battery 1B increases and gas is released from the valve. If the valve is located on one side or the other of first storage battery 1B in the stacking direction (upper or lower side in FIG. 1), the gas will be released from the valve toward the upper second storage battery 2A or the lower second storage battery 2B. If the valve is located on a side of first storage battery 1B in the stacking direction (right, left, front, or rear side in FIG. 1), the gas will be released from the valve toward the wall of housing 4.

[0020] In other words, one way to ensure that the gas emitted due to an increase in pressure inside the first storage battery is directed from the valve toward the second storage battery or toward the wall of the housing is to configure the power supply device so that the first storage batteries are not adjacent to each other.

[0021] First and second storage batteries The first and second storage batteries may be, for example, an electrode stack formed by stacking electrodes. The electrode stack is composed of a plurality of positive electrodes and negative electrodes stacked with separators interposed therebetween.

[0022] (Positive electrode active material layer) The positive electrode has a positive electrode active material layer. The positive electrode active material layer contains a positive electrode active material and may further contain, for example, a binder. The positive electrode active material layer in the first battery contains a nickel-cobalt-manganese-based positive electrode active material. Examples of the positive electrode active material in the first battery include lithium nickel cobalt manganese composite oxide (hereinafter sometimes simply referred to as "LNCM"). The simplest LNCM has the following general formula: LiNi x Co y Mn z O2 (where x, y, z in the formula satisfy 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1). LNCM may contain other additive elements in addition to Li, Ni, Co, and Mn, for example, transition metal elements other than Ni, Co, and Mn, and typical metal elements other than Li. LNCM has a layered crystal structure. LNCM should exceed 50% by mass of the entire positive electrode active material and preferably occupy, for example, 80 to 100% by mass.

[0023] The positive electrode active material layer in the second battery contains an iron phosphate-based positive electrode active material. Examples of the positive electrode active material in the second battery include lithium iron phosphate (LiFePO4, LFP), lithium manganese iron phosphate (LMFP), and the like.

[0024] The positive electrode includes, for example, a positive electrode current collector and a positive electrode active material layer fixed on the positive electrode current collector. As the positive electrode current collector, a conductive member made of a metal with good conductivity (for example, aluminum) is suitable.

[0025] (Negative electrode active material layer) In the first battery and the second battery, the negative electrode has a negative electrode active material layer. The negative electrode active material layer contains a negative electrode active material and may further contain, for example, a binder. Examples of negative electrode active materials include graphite-based carbons such as natural graphite, artificial graphite, and amorphous-coated graphite, metal compounds, elements or compounds thereof that can be alloyed with lithium, and boron-doped carbon. Examples of elements that can be alloyed with lithium include silicon and tin. In graphite-based carbons, the proportion of graphite is generally 50% by mass or more, preferably 80% by mass or more.

[0026] The negative electrode includes, for example, a negative electrode current collector and a negative electrode active material layer fixed onto the negative electrode current collector. The negative electrode current collector is preferably a conductive member made of a metal with good conductivity (e.g., copper).

[0027] (separator) The separator is an electrically insulating porous film. The separator electrically isolates the positive electrode from the negative electrode. The separator may be made of, for example, a porous polyethylene (PE) film, a porous polypropylene (PP) film, or the like. The separator may have a multi-layer structure.

[0028] (electrolyte) The power supply device according to the embodiment of the present disclosure further includes an electrolyte. Examples of the electrolyte include an electrolytic solution, and non-aqueous electrolytic solutions are particularly preferred.

[0029] The non-aqueous electrolytic solution contains a solvent (non-aqueous solvent) and an electrolyte. Examples of the solvent (non-aqueous solvent) include N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(fluorosulfonyl)imide (DEME), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI), and 1-ethyl-2,3-dimethylimidazolium bis(fluorosulfonyl)imide (DEMI-FSI).

[0030] The electrolyte in the electrolytic solution may be, for example, a Li salt. Examples of the Li salt include lithium bis(fluorosulfonyl)imide (LiFSI), LiPF6 (lithium hexafluorophosphate), lithium tetrafluoroborate (LiBF4), and Li[N(CF3SO2)2]. The amount of the electrolyte may be, for example, 1.0 to 2.0 mol / L, and preferably 1.0 to 1.5 mol / L.

[0031] In addition to the solvent and electrolyte, the electrolytic solution may contain various additives such as a thickener, a film-forming agent, a gas generating agent, etc. The electrolyte is typically a non-aqueous electrolytic solution that is liquid at room temperature (e.g., 25±10°C). The electrolytic solution typically remains liquid in the environment in which the battery is used (e.g., a temperature environment of -20 to +60°C).

[0032] ·Applications Examples of applications of the power supply device according to the embodiment of the present disclosure include power sources for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs). [Explanation of symbols]

[0033] 1A, 1B, 1C, 1D 1st storage battery, 2A, 2B, 2C, 2D, 2E 2nd storage battery, 4 boxes, 10 power supplies

Claims

[Claim 1] one or more first storage batteries that are lithium ion batteries containing a nickel-cobalt-manganese based positive electrode active material; one or more second storage batteries that are lithium-ion batteries containing an iron phosphate-based positive electrode active material; a housing that houses the first storage battery and the second storage battery, The housing has a plurality of attachments therein, the first storage battery and the second storage battery are each placed on the attachment; adjacent first storage batteries, adjacent second storage batteries, and adjacent first storage batteries and second storage batteries are all arranged apart from each other; the first storage battery has a valve that opens when the internal pressure of the first storage battery increases to release the internal gas; The gas is ejected from the valve toward the second storage battery or toward a wall of the housing.

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