Charging control method for battery modules and lithium metal secondary batteries

Abstract

This invention provides a battery module capable of charging a lithium metal secondary battery while suppressing capacity degradation, and a charging control method for the lithium metal secondary battery. The battery module comprises: a lithium metal secondary battery having an electrode stack having a negative electrode comprising lithium metal or a lithium alloy; a control mechanism for controlling the charging current of the lithium metal secondary battery; a measuring mechanism for measuring the surface pressure of the lithium metal secondary battery; and a first setting mechanism for setting the charging current of the lithium metal secondary battery based on the surface pressure of the lithium metal secondary battery.

Description

[0001] Cross-referencing of related applications

[0002] This application claims priority based on Japanese Patent Application No. 2025-019948, filed on February 10, 2025, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to a battery module and a charging control method for a lithium metal secondary battery. Background Technology

[0004] A lithium metal secondary battery is a secondary battery that uses lithium metal as the negative electrode. By using lithium metal, the negative electrode can be thinned, and the energy density can be increased.

[0005] Unlike conventional graphite-based anodes, the thickness change of anodes containing lithium metal or lithium alloys under charge-discharge conditions can be observed as surface pressure. It is known that when lithium is deposited from the anode containing lithium metal or lithium alloys during charging of a lithium metal secondary battery, causing porosity, the pressure (surface pressure) at the electrode surface of the anode containing lithium metal or lithium alloys increases. Porosity of the anode containing lithium metal or lithium alloys can lead to its degradation. However, methods are known to suppress the degradation of the anode containing lithium metal or lithium alloys by charging while simultaneously detecting the surface pressure of the lithium metal secondary battery (e.g., see Japanese Patent No. 2023-551995). Summary of the Invention

[0006] The purpose of this invention is to provide a battery module and a charging control method for lithium metal secondary batteries that can charge the battery while suppressing capacity degradation, which helps to stabilize battery performance and thus improve energy efficiency.

[0007] The battery module and the charging control method for the lithium metal secondary battery of one aspect of the present invention adopt the following structure.

[0008] [1] The battery module has the following features:

[0009] A lithium metal secondary battery having an electrode stack having a negative electrode comprising lithium metal or a lithium alloy;

[0010] A control mechanism that controls the charging current of the lithium metal secondary battery;

[0011] The measuring apparatus measures the surface pressure of the lithium metal secondary battery; and

[0012] The first setting mechanism sets the charging current of the lithium metal secondary battery according to the surface pressure of the lithium metal secondary battery.

[0013] According to the above scheme, by using the first setting mechanism to set the charging current according to the surface voltage of the lithium metal secondary battery, the lithium metal secondary battery can be charged while suppressing dendrite growth.

[0014] [2] The lithium metal secondary battery in the above [1] scheme also has a second setting mechanism for setting the charging current of the lithium metal secondary battery according to the resistance of the lithium metal secondary battery during charging.

[0015] According to the above scheme, as a charging current that suppresses the increase in the thickness of the negative electrode containing lithium metal or lithium alloy, the lithium metal secondary battery can be charged while suppressing the capacity degradation of the lithium metal secondary battery caused by the electrolysis of lithium ions from the negative electrode containing lithium metal or lithium alloy.

[0016] [3] In the above [2] scheme, the battery module uses the control mechanism to set the value of the smaller of the charging current set by the first setting mechanism and the charging current set by the second setting mechanism as the final value of the charging current of the lithium metal secondary battery.

[0017] According to the above scheme, the charging current can be set to suppress the growth of dendrites in the negative electrode containing lithium metal or lithium alloy, or to suppress the increase in the thickness of the negative electrode containing lithium metal or lithium alloy. As a result, the lithium metal secondary battery can be charged while suppressing the capacity degradation of the lithium metal secondary battery caused by the electrolysis of lithium ions from the negative electrode containing lithium metal or lithium alloy.

[0018] [4] A charging control method for a lithium metal secondary battery having a negative electrode comprising lithium metal or a lithium alloy has the following characteristics:

[0019] The control process controls the charging current of the lithium metal secondary battery;

[0020] The measurement process includes measuring the surface pressure of the lithium metal secondary battery; and

[0021] The first setting step involves setting the charging current of the lithium metal secondary battery based on the surface pressure of the lithium metal secondary battery.

[0022] According to the above scheme, the charging current used to suppress the growth of dendrites in the negative electrode containing lithium metal or lithium alloy can charge the lithium metal secondary battery while suppressing the capacity degradation of the lithium metal secondary battery caused by the electrolysis of lithium ions from the negative electrode containing lithium metal or lithium alloy.

[0023] [5] The charging control method for the lithium metal secondary battery in the above [4] scheme further includes a second setting step of setting the charging current of the lithium metal secondary battery according to the resistance of the lithium metal secondary battery during charging.

[0024] According to the above scheme, as a charging current to suppress the increase in thickness of the negative electrode containing lithium metal or lithium alloy, the lithium metal secondary battery can be charged while suppressing the capacity degradation of the lithium metal secondary battery caused by the electrolysis of lithium ions from the negative electrode containing lithium metal or lithium alloy.

[0025] [6] In the charging control method of the lithium metal secondary battery in the above-mentioned scheme [4] or [5], the resistance of the lithium metal secondary battery in the second setting step is the largest value among the values ​​obtained by measuring the DC resistance of the lithium metal secondary battery multiple times.

[0026] According to the above scheme, the resistance of lithium metal secondary batteries can be measured more accurately.

[0027] [7] In the lithium metal secondary battery charging control method of the above [6] scheme, the control step is used to set the value of the smaller of the charging current set by the first setting step and the charging current set by the second setting step as the final value of the charging current of the lithium metal secondary battery.

[0028] According to the above scheme, the charging current can be set to suppress the growth of dendrites in the negative electrode containing lithium metal or lithium alloy, or to suppress the increase in the thickness of the negative electrode containing lithium metal or lithium alloy. As a result, the lithium metal secondary battery can be charged while suppressing the capacity degradation of the lithium metal secondary battery caused by the electrolysis of lithium ions from the negative electrode containing lithium metal or lithium alloy.

[0029] According to the present invention, a battery module capable of charging a lithium metal secondary battery while suppressing capacity degradation and a charging control method for the lithium metal secondary battery can be provided. Attached Figure Description

[0030] Figure 1 This is a block diagram illustrating a battery module according to one embodiment of the present invention. Detailed Implementation

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0032] [Battery Module]

[0033] Figure 1 This is a block diagram illustrating a battery module according to one embodiment of the present invention. Figure 1As shown, the battery module 1 of this embodiment includes a lithium metal secondary battery 10, a control mechanism 20, a measuring mechanism 30, and a first setting mechanism 40.

[0034] The lithium metal secondary battery 10 includes an electrode stack. The electrode stack includes a positive electrode, a negative electrode, a separator disposed between the positive and negative electrodes, and an electrolyte. Alternatively, a solid electrolyte can be used instead of the electrolyte and separator.

[0035] (positive electrode)

[0036] The positive electrode includes a positive current collector layer and a positive active material layer. For example, aluminum can be used as the material for the positive current collector layer. The positive active material layer contains the positive active material. Examples of positive active materials include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and LiNi... p Mn q Co r O2 (p+q+r=1), LiNi p Al q Co r O2 (p+q+r=1), lithium manganese oxide (LiMn2O4), and Li 1+x Mn 2-x-y M y O4 (x+y=2, M=at least one selected from Al, Mg, Co, Fe, Ni and Zn) represents heteroelement-substituted Li-Mn spinel, lithium titanate (an oxide containing Li and Ti), lithium metal phosphate (LiMPO4, M=at least one selected from Fe, Mn, Co and Ni), etc. The positive electrode active material layer may also include various additives used as materials for the positive electrode active material layer, such as binders and conductive additives.

[0037] (negative electrode)

[0038] The negative electrode comprises a negative electrode current collector layer and a negative electrode active material layer. For example, copper can be used as the material for the negative electrode current collector layer. The negative electrode active material layer comprises a negative electrode active material. Lithium metal or a metal alloyed with lithium can be used as the negative electrode active material. Examples of metals alloyed with lithium include Mg, Si, Au, Ag, In, Ge, Sn, Pb, Al, and Zn. Furthermore, carbonaceous materials can be included as the negative electrode active material. Examples of carbonaceous materials include natural graphite, artificial graphite, mesophase carbon microspheres (MCMB), hard carbon, and soft carbon.

[0039] (Electrolyte)

[0040] The electrolyte comprises an organic solvent and an electrolyte. Examples of organic solvents include cyclic polycarbonates, chain polycarbonates, cyclic ethers, chain ethers, hydrofluoroethers, aromatic ethers, sulfones, cyclic esters, chain carboxylic esters, and nitriles. Examples of cyclic polycarbonates include ethylene carbonate, propylene carbonate, vinylene carbonate, and fluoroethylene carbonate. Examples of chain polycarbonates include dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. Examples of cyclic ethers include tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, and 4-methyl-1,3-dioxolane. Examples of chain ethers include 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, and diethyl ether. Examples of hydrofluoroethers include 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, bis(2,2,2-trifluoroethyl) ether, and 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane. Examples of aromatic ethers include anisole. Examples of sulfones include sulfolane and methylsulfolane. Examples of cyclic esters include γ-butyrolactone. Examples of chain carboxylic acid esters include acetates, butyrates, and propionates. Examples of nitriles include acetonitrile and propionitrile. Organic solvents can be used alone or in combination of two or more.

[0041] Electrolytes are the source of lithium ions that act as a charge-moving medium, and they contain lithium salts. Examples of lithium salts include LiPF6, LiBF4, LiClO4, LiAsF6, LiCF3SO3, LiC(CF3SO2)3, LiN(CF3SO2)2 (LiTFSI), LiN(FSO2)2 (LiFSI), and LiBC4O8. Lithium salts can be used alone or in combination of two or more.

[0042] (Solid electrolyte)

[0043] As a solid electrolyte, sulfide-based solid electrolytes can be used, for example. Examples of sulfide-based solid electrolytes include Li₂S-P₂S₅, Li₂S-P₂S₅-LiI, Li₂S-P₂S₅-Li₂O, Li₂S-P₂S₅-Li₂O-LiI, LiS-SiS₂, Li₂S-SiS₂-Li, Li₂S-SiS₂-LiBr, Li₂S-SiS₂-LiCl, Li₂S-SiS₂-B₂S₃-LiI, Li₂S-SiS₂-P₂S₅-LiI, Li₂S-B₂S₃, and Li₂S-P₂S₅-Z. m S n(Where m and n are positive numbers, and Z is any one of Ge, Zn, and Ga.) Li₂S-GeS₂, Li₂S-SiS₂-Li₃PO₄, Li₂S-SiS₂-Li x MO y (Where x and y are positive numbers, and M is any one of P, Si, Ge, B, Al, Ga, and In.)

[0044] (Diaphragm)

[0045] There are no particular limitations on the materials used to form the diaphragm, but examples include polyethylene, polyolefins such as polypropylene, aromatic polyamides, polyimides, fluoropolymers, glass fibers, and cellulose fibers.

[0046] The control mechanism 20 is a device for controlling the charging current of the lithium metal secondary battery 10.

[0047] The measuring mechanism 30 is a device for measuring the surface pressure of the lithium metal secondary battery 10. For example, a pressure sensor can be used as the measuring mechanism 30. The surface pressure of the lithium metal secondary battery 10 refers to the pressure generated on the electrode surface of the electrode stack within the lithium metal secondary battery 10. It should be noted that the surface pressure of the lithium metal secondary battery 10 is related to the growth of dendrites in the negative electrode containing lithium metal or a lithium alloy.

[0048] The first setting mechanism 40 sets the charging current of the lithium metal secondary battery 10 based on the surface voltage of the lithium metal secondary battery 10. As a result, the charging current, which suppresses the growth of dendrites in the negative electrode containing lithium metal or lithium alloy, can charge the lithium metal secondary battery 10 while suppressing the capacity degradation of the lithium metal secondary battery 10 caused by the electrolysis of lithium ions from the negative electrode containing lithium metal or lithium alloy.

[0049] The battery module 1 in this embodiment preferably further includes a second setting mechanism 50 for setting the charging current of the lithium metal secondary battery 10 based on the resistance of the lithium metal secondary battery 10 during charging. It should be noted that the resistance of the lithium metal secondary battery 10 is related to the thickness of the negative electrode containing lithium metal or lithium alloy. Therefore, as a charging current that suppresses the increase in the thickness of the negative electrode containing lithium metal or lithium alloy, the lithium metal secondary battery 10 can be charged while suppressing the capacity degradation of the lithium metal secondary battery 10 caused by the electrolysis of lithium ions from the negative electrode containing lithium metal or lithium alloy.

[0050] In the battery module 1 of this embodiment, it is preferable that the control mechanism 20 sets the smaller of the charging current set by the first setting mechanism 40 and the charging current set by the second setting mechanism 50 as the final value of the charging current of the lithium metal secondary battery 10. This allows the charging current to be set to suppress dendrite growth in the negative electrode containing lithium metal or lithium alloy, or to suppress the increase in the thickness of the negative electrode containing lithium metal or lithium alloy. As a result, the lithium metal secondary battery 10 can be charged while suppressing capacity degradation caused by the electrolysis of lithium ions from the negative electrode containing lithium metal or lithium alloy.

[0051] According to the battery module 1 of this embodiment, by using the first setting mechanism 40 to set the charging current of the lithium metal secondary battery 10 according to the surface pressure of the lithium metal secondary battery 10, the charging current is used to suppress the growth of dendrites in the negative electrode containing at least lithium metal or lithium alloy. This allows the lithium metal secondary battery to be charged while suppressing the capacity degradation of the lithium metal secondary battery 10 caused by the electrolysis of lithium ions from the negative electrode containing lithium metal or lithium alloy.

[0052] [Charging control method for lithium metal secondary batteries]

[0053] One embodiment of the present invention provides a charging control method for a lithium metal secondary battery comprising a negative electrode containing lithium metal or a lithium alloy, and includes: a control step for controlling the charging current of the lithium metal secondary battery; a measurement step for measuring the surface pressure of the lithium metal secondary battery; and a first setting step for setting the charging current of the lithium metal secondary battery based on the surface pressure of the lithium metal secondary battery.

[0054] "Controlling the process"

[0055] In the control process, the charging current of the lithium metal secondary battery is controlled. In the control process, the charging current is controlled in a manner that becomes the charging current set by the first setting process or the second setting process described later.

[0056] "Measurement process"

[0057] In the measurement process, the surface pressure of the lithium metal secondary battery is measured. For example, a pressure sensor is used to measure the surface pressure of the lithium metal secondary battery in this process.

[0058] "First setting process"

[0059] In the first setting step, the charging current of the lithium metal secondary battery is set based on the surface pressure of the lithium metal secondary battery obtained from the measurement step. By setting the charging current of the lithium metal secondary battery based on the surface pressure of the lithium metal secondary battery in the first setting step, a charging current that suppresses the growth of dendrites in the negative electrode containing lithium metal or lithium alloy can be used to charge the lithium metal secondary battery while suppressing the capacity degradation of the lithium metal secondary battery caused by the electrolysis of lithium ions from the negative electrode containing lithium metal or lithium alloy. It should be noted that the surface pressure of the lithium metal secondary battery is related to the growth of dendrites in the negative electrode containing lithium metal or lithium alloy. Therefore, in the first step, the charging current is set in a way that suppresses dendrite growth based on the relationship between the pre-measured surface pressure of the lithium metal secondary battery and the degree of dendrite growth in the negative electrode containing lithium metal or lithium alloy.

[0060] "Second Setting Process"

[0061] The preferred method for charging a lithium metal secondary battery in this embodiment further includes a second setting step of setting the charging current of the lithium metal secondary battery based on the resistance of the lithium metal secondary battery during charging. By using the second setting step to set the charging current of the lithium metal secondary battery based on the resistance of the lithium metal secondary battery during charging, and thus using a charging current that suppresses the increase in the thickness of the negative electrode containing lithium metal or lithium alloy, the lithium metal secondary battery can be charged while suppressing the capacity degradation of the lithium metal secondary battery caused by the electrolysis of lithium ions from the negative electrode containing lithium metal or lithium alloy. It should be noted that the resistance of the lithium metal secondary battery 10 is related to the thickness of the negative electrode containing lithium metal or lithium alloy. Therefore, in the second step, based on a pre-measured relationship between the resistance of the lithium metal secondary battery during charging and the degree of increase in the thickness of the negative electrode containing lithium metal or lithium alloy, the charging current is set in a manner that suppresses the increase in the thickness of the negative electrode containing lithium metal or lithium alloy.

[0062] In the second setting process, the resistance of the lithium metal secondary battery is preferably the maximum value obtained from multiple measurements of the direct current resistance (DCR) of the lithium metal secondary battery. By obtaining the maximum value obtained from multiple measurements of the DC resistance of the lithium metal secondary battery, the resistance of the lithium metal secondary battery can be measured more accurately.

[0063] In the charging control method for a lithium metal secondary battery according to this embodiment, it is preferable to use a control step to set the smaller of the charging current set by a first setting step and the charging current set by a second setting step as the final value of the charging current for the lithium metal secondary battery. This allows the charging current to be set to suppress dendrite growth in the negative electrode containing lithium metal or lithium alloy, or to suppress the increase in the thickness of the negative electrode containing lithium metal or lithium alloy. As a result, the lithium metal secondary battery can be charged while suppressing capacity degradation caused by the electrolysis of lithium ions from the negative electrode containing lithium metal or lithium alloy.

[0064] According to the charging control method for lithium metal secondary batteries of this embodiment, by using a first setting step to set the charging current of the lithium metal secondary battery based on the surface voltage of the lithium metal secondary battery, the charging current is used as a charging current to suppress the growth of dendrites in the negative electrode containing lithium metal or lithium alloy. This allows the lithium metal secondary battery to be charged while suppressing the capacity degradation of the lithium metal secondary battery caused by the electrolysis of lithium ions from the negative electrode containing lithium metal or lithium alloy.

[0065] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments and various modifications and alterations can be made within the scope of the spirit of the present invention as described in the patent technical solution.

Claims

1. A battery module, wherein, The battery module includes: A lithium metal secondary battery having an electrode stack having a negative electrode comprising lithium metal or a lithium alloy; A control mechanism that controls the charging current of the lithium metal secondary battery; A testing apparatus that measures the surface pressure of the lithium metal secondary battery; as well as The first setting mechanism sets the charging current of the lithium metal secondary battery based on the surface pressure of the lithium metal secondary battery.

2. The battery module according to claim 1, wherein, The battery module also includes a second setting mechanism for setting the charging current of the lithium metal secondary battery based on the resistance of the lithium metal secondary battery during charging.

3. The battery module according to claim 2, wherein, Using the control mechanism, the smaller of the charging current set by the first setting mechanism and the charging current set by the second setting mechanism is set as the final value of the charging current of the lithium metal secondary battery.

4. A charging control method for a lithium metal secondary battery, comprising a negative electrode containing lithium metal or a lithium alloy, wherein... The charging control method for the lithium metal secondary battery has the following features: The control process controls the charging current of the lithium metal secondary battery; The measurement process involves measuring the surface pressure of the lithium metal secondary battery. as well as The first setting step involves setting the charging current of the lithium metal secondary battery based on the surface pressure of the lithium metal secondary battery.

5. The charging control method for a lithium metal secondary battery according to claim 4, wherein, The charging control method for the lithium metal secondary battery further includes a second setting step of setting the charging current of the lithium metal secondary battery based on the resistance of the lithium metal secondary battery during charging.

6. The charging control method for a lithium metal secondary battery according to claim 5, wherein, The resistance of the lithium metal secondary battery in the second setting process is the largest value among the values ​​obtained by measuring the DC resistance of the lithium metal secondary battery multiple times.

7. The charging control method for a lithium metal secondary battery according to claim 5, wherein, Using the control process, the smaller of the charging current set by the first setting process and the charging current set by the second setting process is set as the final value of the charging current of the lithium metal secondary battery.

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