Battery Usage Instructions

Abstract

To provide a battery whose battery capacity decrease can be suppressed, a manufacturing method for a battery, and a using method for a battery.SOLUTION: A battery 1 according to the present disclosure includes a negative electrode layer NL, an alloy layer AL, and a positive electrode layer PL. The negative electrode layer NL contains a negative electrode active material. The alloy layer AL exists between the negative electrode layer NL and a current collector C, and contains lithium alloy having a higher electrode potential than the negative electrode active material contained in the negative electrode layer NL. The positive electrode layer PL contains a lithium compound as a positive electrode active material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to batteries, methods for manufacturing batteries, and methods for using batteries. [Background technology]

[0002] Patent Document 1 discloses a sheet battery. The sheet battery described in Patent Document 1 comprises a bipolar electrode unit having a positive electrode active material layer on one side of a current collector and a negative electrode active material layer on the other side of the current collector, and a solid electrolyte. The sheet battery described in Patent Document 1 prevents self-discharge between the positive electrode active material layer and the negative electrode active material layer by using a solid electrolyte as the electrolyte. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2000-100471 [Overview of the project] [Problems that the invention aims to solve]

[0004] Incidentally, it is known that in lithium-ion secondary batteries, which are a typical example of sheet-type batteries as described in Patent Document 1, the battery capacity gradually decreases with repeated charging and discharging.

[0005] One of the reasons for the decrease in battery capacity of lithium-ion secondary batteries is the degradation of lithium exchanged between the positive and negative electrodes. Conventional lithium-ion secondary batteries lacked a method for replenishing depleted lithium. Therefore, batteries experiencing a decrease in capacity due to lithium degradation had to continue being used in that reduced capacity state.

[0006] That is, in the lithium-ion secondary battery according to the prior art, there is a problem that the decrease in battery capacity cannot be sufficiently suppressed. Patent Document 1 does not disclose a technique capable of solving the above problems.

[0007] The present disclosure has been made to solve such problems, and an object thereof is to provide a battery capable of suppressing a decrease in battery capacity, a method for manufacturing the battery, and a method for using the battery.

Means for Solving the Problems

[0008] The battery according to one aspect of the present disclosure includes a negative electrode layer containing a negative electrode active material, an alloy layer containing a lithium alloy that is located between the negative electrode layer and the current collector and has an electrode potential higher than that of the negative electrode active material, and a positive electrode layer containing a lithium compound as a positive electrode active material. It is a battery.

[0009] The method for manufacturing a battery according to one aspect of the present disclosure includes a step of forming a metal layer containing a metal, a step of forming a negative electrode layer containing a negative electrode active material, a step of forming a positive electrode layer containing a lithium compound as a positive electrode active material, a step of laminating the metal layer, the negative electrode layer, and the positive electrode layer, and a step of generating an alloy of the metal and lithium in the metal layer by applying an electric current to the laminated metal layer, negative electrode layer, and positive electrode layer. It is a method for manufacturing a battery.

[0010] The method for using a battery according to one aspect of the present disclosure includes defining a first discharge voltage and a second voltage having a value smaller than the first voltage value for the above-described battery, when the battery capacity of the battery is larger than a predetermined value, discharging the battery so that the discharge voltage of the battery does not fall below the first discharge voltage, When the battery capacity of the battery is smaller than a predetermined value, the battery is discharged until the discharge voltage of the battery becomes a second discharge voltage. This is a method of using a battery.

Effects of the Invention

[0011] According to the present disclosure, it is possible to provide a battery capable of suppressing a decrease in battery capacity, a method for manufacturing a battery, and a method for using a battery.

Brief Description of the Drawings

[0012] [Figure 1] FIG. 1 is a schematic cross-sectional view showing the configuration of a battery according to a first embodiment. [Figure 2] FIG. 2 is a flowchart showing a method of using a battery according to a first embodiment. [Figure 3] FIG. 3 is a flowchart showing a method of manufacturing a battery according to a first embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view for explaining a method of manufacturing a battery according to a first embodiment. [Figure 5] FIG. 5 is a graph showing the results of a performance test in an example.

Modes for Carrying Out the Invention

[0013] (First Embodiment) <Configuration of the Battery> Hereinafter, a first embodiment according to the present disclosure will be described in detail with reference to the drawings. First, the configuration of the battery according to the present embodiment will be described in detail. FIG. 1 is a schematic cross-sectional view showing the configuration of the battery according to the first embodiment.

[0014] FIG. 1(a) is a schematic cross-sectional view showing a part of the battery according to the first embodiment. The battery 1 according to the present embodiment is a lithium ion secondary battery having a stacked structure as shown in FIG. 1(a). The battery 1 according to the present embodiment includes a positive electrode layer PL, a negative electrode layer NL, an alloy layer AL, a current collector C, and an electrolyte layer EL.

[0015] For example, the battery 1 according to this embodiment may be a bipolar lithium-ion secondary battery having a structure in which a plurality of bipolar electrodes are stacked with an electrolyte layer EL in between. Figure 1(b) is a schematic cross-sectional view showing an example of the electrode configuration used in the battery according to this embodiment. The bipolar electrode BE shown in Figure 1(b) has a negative electrode layer NL and an alloy layer AL on one side of the current collector C. Furthermore, the bipolar electrode BE has a positive electrode layer PL on the other side of the current collector C. By stacking bipolar electrodes BE as shown in Figure 1(b) via an electrolyte layer EL, a stacked structure as shown in Figure 1(a) can be constructed inside the battery 1.

[0016] However, the battery according to this embodiment is not limited to a bipolar type. Figures 1(c) and 1(d) are schematic cross-sectional views showing other examples of electrode configurations used in the battery according to this embodiment. The negative electrode NE shown in Figure 1(c) has a negative electrode layer NL and an alloy layer AL on both sides of the current collector C. The positive electrode PE shown in Figure 1(d) has a positive electrode layer PL on both sides of the current collector C.

[0017] The battery according to this disclosure may be, for example, a lithium secondary battery in which a negative electrode NE shown in Figure 1(c) and a positive electrode PE shown in Figure 1(d) are alternately stacked with an electrolyte layer EL in between. With this configuration, a layered structure as shown in Figure 1(a) can be formed in battery 1.

[0018] Furthermore, the batteries related to this disclosure are not limited to stacked batteries. For example, the battery according to this disclosure may be constructed by immersing a current collector C having a positive electrode layer PL and a current collector C having a negative electrode layer NL and an alloy layer AL in an electrolyte.

[0019] In other words, the battery according to this disclosure may have any configuration as long as it comprises a positive electrode layer PL, a negative electrode layer NL, an alloy layer AL, and a current collector C, with the alloy layer AL located between the negative electrode layer NL and the current collector C.

[0020] Let's return to the explanation of Figure 1(a). Current collector C is a conductor. Current collector C has a positive electrode layer PL and an alloy layer AL on its surface. In addition, current collector C has a negative electrode layer NL on its surface via the alloy layer AL.

[0021] If battery 1 is a bipolar battery, the current collector C is a plate-shaped conductor, with a negative electrode layer NL and an alloy layer AL on one side and a positive electrode layer PL on the other side. Furthermore, if battery 1 is a battery other than a bipolar type, some current collectors C have a negative electrode layer NL and an alloy layer AL on their surface, and some current collectors C have a positive electrode layer PL on their surface.

[0022] During the discharge of battery 1, the current collector C receives electrons from the negative electrode layer NL via the alloy layer AL and supplies electrons to the positive electrode layer PL. Furthermore, during the charging of battery 1, the current collector C receives electrons from the positive electrode layer PL and supplies electrons to the negative electrode layer NL via the alloy layer AL.

[0023] The current collector C may be made of any material that is applicable to the current collector of a lithium-ion secondary battery. The material used for the current collector C may be, for example, a metal or a conductive resin.

[0024] Specific examples of materials used for the current collector C include carbon-containing acrylic resin, polythiophene-based resin, polyacetylene-based resin, polyaniline-based resin, copper, and aluminum.

[0025] The positive electrode layer PL is a layer formed on the surface of the current collector C. The positive electrode layer PL contains a lithium compound as the positive electrode active material. During the discharge of battery 1, the positive electrode layer PL accepts electrons from the current collector C and lithium ions from the electrolyte layer EL. During the charging of battery 1, the positive electrode layer PL releases electrons to the current collector C and lithium ions to the electrolyte layer EL.

[0026] The positive electrode active material contained in the positive electrode layer PL can be any lithium compound that is applicable as a positive electrode active material for lithium-ion secondary batteries. For example, the positive electrode active material contained in the positive electrode layer PL may be a substance containing oxides of cobalt, nickel, iron, manganese, aluminum, etc., or it may contain phosphate compounds of these metals.

[0027] Specific examples of positive electrode active materials contained in the positive electrode layer PL include LiCoO2, LiNiO2, LiMn2O4, and LiNi x Co y O2, LiLiLi x Co y Al z O2, LiLiLi x Co y Mn z Examples include O2 and LiFePO4. However, in the above empirical formulas, x, y, and z are real numbers of 0 or greater.

[0028] The negative electrode layer NL is a layer formed on the surface of the current collector C via the alloy layer AL. The negative electrode layer NL contains the negative electrode active material. During the discharge of battery 1, the negative electrode layer NL releases electrons to the current collector C via the alloy layer AL and releases lithium ions to the electrolyte layer EL. During the charging of battery 1, the negative electrode layer NL accepts electrons from the current collector C via the alloy layer AL and accepts lithium ions from the electrolyte layer EL.

[0029] More specifically, the negative electrode layer NL contains a negative electrode active material with a lower electrode potential than the lithium alloy contained in the alloy layer AL. However, the electrode potential referred to here may refer to, for example, the standard electrode potential. In this specification, the electrode potential may be used as an index for evaluating the difficulty of occurrence of the electrode reaction at the negative electrode during discharge. Therefore, a low electrode potential as referred to here means that the electrode reaction at the negative electrode during discharge is more likely to occur.

[0030] That is, the negative electrode active material having an electrode potential lower than that of the lithium alloy contained in the alloy layer AL referred to here means a negative electrode active material that is more likely to release lithium ions and electrons than the lithium alloy contained in the alloy layer AL during discharge of the battery. Note that the negative electrode active material having an electrode potential lower than that of the lithium alloy contained in the alloy layer AL may be rephrased as a more electrochemically negative negative electrode active material than the lithium alloy contained in the alloy layer AL.

[0031] The negative electrode active material contained in the negative electrode layer NL may be any compound that is applicable as a negative electrode active material for a lithium ion secondary battery. The negative electrode active material contained in the negative electrode layer NL may be, for example, a negative electrode active material such as a graphite-based, silicon-based, or titanium oxide-based material. Specific examples of the negative electrode active material contained in the negative electrode layer NL include LiC6, Li 4.4 Si, Li4Ti5O 12 and the like.

[0032] The electrolyte layer EL is a layer located between the positive electrode layer PL and the negative electrode layer NL and contains an electrolyte capable of accepting lithium ions. During discharge of the battery 1, the electrolyte layer EL accepts lithium ions from the negative electrode layer NL and inserts the lithium ions into the positive electrode layer PL. Also, during charging of the battery 1, the electrolyte layer EL accepts lithium ions from the positive electrode layer PL and inserts the lithium ions into the negative electrode layer NL.

[0033] The solid electrolyte contained in the electrolyte layer EL may be any compound that is applicable as a solid electrolyte for a lithium ion secondary battery. The electrolyte used as the main component of the electrolyte layer EL may be a sulfide-based electrolyte, and a specific example is Li a Si b P c S d Cl e Li a Ge b P c S d Li a P b S c Cl d Li a P b S c Examples of compounds represented by the following compositional formulas are given. However, in the above compositional formulas, a, b, c, d, and e are each real numbers of 0 or greater.

[0034] The alloy layer AL is located between the negative electrode layer and the current collector and contains a lithium alloy. More specifically, the alloy layer AL contains a lithium alloy with a higher electrode potential than the negative electrode active material contained in the negative electrode layer NL.

[0035] As described above, in this specification, electrode potential may be used as an indicator for evaluating the likelihood of electrode reaction occurring at the negative electrode during discharge. Therefore, a lithium alloy with a higher electrode potential than the negative electrode active material contained in the negative electrode layer NL, as referred to here, means a lithium alloy that releases lithium ions and electrons less readily than the negative electrode active material contained in the negative electrode layer NL during battery discharge. Furthermore, "a lithium alloy with a higher electrode potential than the negative electrode active material contained in the negative electrode layer NL" can be rephrased as "a lithium alloy that is nobler than the negative electrode active material contained in the negative electrode layer NL."

[0036] During the discharge of battery 1, the alloy layer AL transfers electrons emitted from the negative electrode layer NL to the current collector C. Furthermore, during the charging of battery 1, the alloy layer AL transfers electrons received from the current collector C to the negative electrode layer NL.

[0037] Furthermore, during the process of discharging the battery 1 until it reaches the second discharge voltage described later, the alloy layer AL releases the lithium contained in the lithium alloy as lithium ions to the negative electrode layer NL. Here, the step of discharging battery 1 until it reaches the second discharge voltage, which will be described later, is performed when the battery capacity of battery 1 decreases.

[0038] In other words, when the battery capacity of battery 1 decreases, the alloy layer AL releases the lithium contained in the lithium alloy as lithium ions to the negative electrode layer NL. With this configuration, the battery 1 according to this embodiment can replenish the lithium moving between the positive electrode layer PL and the negative electrode layer NL when the battery capacity of the battery 1 decreases. As a result, the battery 1 according to this embodiment can suppress the decrease in battery capacity.

[0039] Examples of alloys contained in the alloy layer AL include alloys of lithium with one or more metals selected from the group consisting of tin, aluminum, bismuth, indium, silver, and antimony.

[0040] A suitable combination of the negative electrode active material contained in the negative electrode layer NL and the alloy contained in the alloy layer AL is, for example, Li 4.4 One example is a combination of silicon and lithium-tin alloy. However, the combination of the negative electrode active material contained in the negative electrode layer NL and the alloy contained in the alloy layer AL is not limited to this; any combination is acceptable as long as the electrode potential of the lithium alloy is higher than that of the negative electrode active material contained in the negative electrode layer NL.

[0041] <How to use the batteries> Next, the method of using the battery according to the first embodiment will be described in detail. Figure 2 is a flowchart illustrating the method of using the battery according to the first embodiment. In the following explanation, please refer to Figure 1(a) as appropriate.

[0042] In the battery usage method according to this embodiment, a first discharge voltage and a second discharge voltage that is smaller than the first voltage value are defined for the battery 1. Here, it is preferable that the first discharge voltage is a voltage greater than the discharge voltage at which lithium ions begin to be released from the alloy layer AL. Furthermore, it is preferable that the second discharge voltage is a voltage smaller than the discharge voltage at which lithium ions begin to be released from the alloy layer AL.

[0043] In the battery usage method according to this embodiment, first, the battery is discharged so that the voltage does not fall below a first discharge voltage (step ST101). The discharge performed in step ST101 may be a discharge to utilize the power stored in battery 1 for various purposes. In other words, step ST101 may be a step that utilizes battery 1.

[0044] Step ST101 may be performed multiple times before step ST102 is executed. In this case, step ST101 may be a process of discharging and charging the battery so that the voltage does not fall below the first discharge voltage. For example, the user of battery 1 may perform step ST102 after performing step ST101 a predetermined number of times.

[0045] Next, a step (ST102) is performed to determine whether the battery capacity is less than a predetermined value. If the battery capacity is not less than a predetermined value (step ST102 NO), the battery usage method according to the first embodiment is completed.

[0046] If the battery capacity is less than a predetermined value (step ST102 YES), the battery is discharged until it reaches a second discharge voltage (step ST103), and the battery usage method according to the first embodiment is completed.

[0047] As described above, by performing step ST103, the alloy layer AL releases lithium ions to the negative electrode layer NL. When the alloy layer AL releases lithium ions to the negative electrode layer NL, the lithium moving between the positive electrode layer PL and the negative electrode layer NL is replenished.

[0048] In other words, by performing step ST103, lithium moving between the positive electrode layer PL and the negative electrode layer NL is replenished. As a result, by performing step ST103, the decrease in battery capacity of battery 1 caused by the loss of lithium moving between the positive electrode layer PL and the negative electrode layer NL is suppressed.

[0049] <Battery manufacturing method> Next, the method for manufacturing the battery according to the first embodiment will be described in detail. Figure 3 is a flowchart illustrating the manufacturing method of the battery according to the first embodiment. Figure 4 is a schematic cross-sectional view illustrating the manufacturing method of the battery according to the first embodiment. More specifically, Figure 4 is a schematic cross-sectional view showing the configuration of the battery 1 at the time when step ST204 shown in Figure 3 is completed.

[0050] In the battery manufacturing method according to the first embodiment, first, a step of forming a metal layer (step ST201) is performed. Here, the metal layer is a film containing a metal that serves as a precursor to the lithium alloy contained in the aforementioned alloy layer AL. In other words, the metal layer is a film corresponding to the alloy layer AL of battery 1, but differs from the alloy layer AL in that it does not contain lithium.

[0051] In step ST201, the metal layer may be formed on the surface of the current collector C, for example, by ion sputtering. Furthermore, in step ST201, the metal layer may be formed, for example, on the surface of a plate-like member or film using an ion sputtering method. The metal layer may then be peeled off from the plate-like member or film.

[0052] Next, the process of forming the negative electrode layer (step ST202) is performed. For example, the negative electrode layer may be formed by applying a negative electrode slurry containing a negative electrode active material, a binder, and a solvent onto the surface of a plate-like member or film, and then drying the applied negative electrode slurry. The negative electrode layer may then be peeled off from the surface of the plate-like member or film. Alternatively, for example, the negative electrode layer may be formed by applying a negative electrode slurry to the surface of the metal layer described above and drying the applied negative electrode slurry.

[0053] Next, the process of forming a positive electrode layer (step ST203) is performed. For example, the positive electrode layer may be formed by applying a positive electrode slurry containing a positive electrode active material, a binder, and a solvent onto the surface of a plate-like member or film, and then drying the applied negative electrode slurry. The positive electrode layer may then be peeled off from the surface of the plate-like member or film. Alternatively, for example, the positive electrode layer may be formed by applying a positive electrode slurry to the surface of the current collector and drying the applied positive electrode slurry.

[0054] Steps ST201 to ST203 may be executed in an order different from the one described above. Furthermore, steps ST201 to ST203 may be executed in parallel.

[0055] Next, the metal layer, negative electrode layer, and positive electrode layer, which were fabricated in steps ST201 to ST203, are laminated (step ST204). More specifically, the metal layer, negative electrode layer, and positive electrode layer are laminated in the arrangement shown in Figure 4.

[0056] In other words, in step ST204, the metal layer ML is laminated so as to be located between the negative electrode layer NL and the current collector C. Furthermore, in step ST204, the positive electrode layer PL and the negative electrode layer NL are stacked facing each other via the electrolyte layer EL.

[0057] Finally, the process of applying current to the metal layer, the negative electrode layer, and the positive electrode layer (step ST205) is performed, and the method for manufacturing the battery according to this embodiment is completed. More specifically, in step ST205, by applying current to the metal layer, the negative electrode layer, and the positive electrode layer, an alloy of the metal contained in the metal layer and lithium is formed in the metal layer. In other words, by performing step ST205, the metal layer ML is converted into the alloy layer AL. Step ST205 may also be performed as a step to charge the battery 1.

[0058] By using the manufacturing method described above, the battery 1 according to this embodiment can be manufactured. [Examples]

[0059] The negative electrode for a secondary battery according to the first embodiment will be described in more detail below. However, the negative electrode for a secondary battery according to the first embodiment is not limited to the following embodiments.

[0060] (Examples) <Fabrication of the positive electrode layer> LiRing 0.8 Co 0.15 Al 0.05 O2, Li2S-P2S5, vapor-deposited carbon fiber, PVDF (Polyvinylidene DiFluoride) binder, and butyl butyrate were mixed in a weight ratio of 88.2:9.8:1.3:0.7 and stirred using an ultrasonic disperser. The resulting mixture was applied as a positive electrode slurry onto aluminum foil and stainless steel foil, respectively, and these were heated and dried using a hot plate to create a positive electrode layer.

[0061] <Fabrication of the negative electrode layer> Powdered silicon, Li2S-P2S5, PVDF-based binder, and vapor-evolved carbon fibers were mixed in a weight ratio of 100:77.6:2:15 and stirred using an ultrasonic dispersion device. The resulting mixture was applied as a negative electrode slurry onto nickel foil and stainless steel foil, respectively, and these were heated and dried using a hot plate to create a negative electrode layer.

[0062] <Preparation of a solid electrolyte layer> A Li2S-P2S5:PVDF-based binder was mixed in a weight ratio of 99.4:0.4 and stirred using an ultrasonic dispersion device. The resulting mixture was applied to the positive electrode layer as an electrolyte layer slurry to create the electrolyte layer.

[0063] <Manufacturing of current collectors> Carbon, acrylic resin, and solvent were mixed to obtain a paste-like mixture. The resulting mixture was applied to a PET (PolyEthylene Terephthalate) film and then heat-dried. The PET film was peeled off from the thin film obtained to obtain a foil-shaped current collector.

[0064] <Fabrication of metal layers> A tin metal layer was fabricated on one side of a foil-shaped current collector by ion sputtering.

[0065] <Battery manufacturing> A stainless steel foil with a negative electrode layer on its surface and an aluminum foil with a positive electrode layer and a solid electrolyte layer on its surface were laminated in the order of stainless steel foil, negative electrode layer, solid electrolyte layer, positive electrode layer, and aluminum foil. The resulting laminate was pressed while being heated using a roll press machine. The stainless steel foil was peeled off from the pressed laminate to obtain the first laminate.

[0066] A nickel foil with a negative electrode layer on its surface and a stainless steel foil with a positive electrode layer and a solid electrolyte layer on its surface were laminated in the order of nickel foil, negative electrode layer, solid electrolyte layer, positive electrode layer, and stainless steel foil. The resulting laminate was pressed while being heated using a roll press machine. The stainless steel foil was peeled off from the pressed laminate to obtain a second laminate.

[0067] The first laminate, the second laminate, and a current collector with a metal layer on its surface were laminated in the following order: nickel foil, negative electrode layer, solid electrolyte layer, positive electrode layer, current collector, metal layer, negative electrode layer, solid electrolyte layer, positive electrode layer, and aluminum foil. The resulting laminate was pressed while being heated using a roll press machine. A 1 cm² circular laminate was punched out from the pressed laminate to form the third laminate. The third laminate was sandwiched between two restraining plates to fabricate the battery according to this embodiment.

[0068] (Comparative example) A battery was fabricated in the same manner as in the examples, except that a metal layer was not formed.

[0069] (Charge / Discharge Test) The fabricated battery was charged with a constant current of 1 / 10C until the control voltage reached 8.10V. Then, the fabricated battery was charged with a constant voltage of 8.10V until the current reached 1 / 100C. Hereafter, the above process will be referred to as the charging process.

[0070] Note that the unit of current, C (C), is the C rate, and the same applies in the process described later. 1C is defined as the magnitude of the constant current required to completely discharge a battery from a fully charged state in one hour.

[0071] Next, the fabricated battery was subjected to constant current discharge at a current of 1 / 10C until the control voltage reached 5.0V. Then, the fabricated battery was subjected to constant voltage discharge at a control voltage of 5.0V until the current reached 1 / 100C. Hereafter, the above process will be referred to as the discharge process. The discharge process corresponds to step ST103 in Figure 2, that is, the process of discharging the battery until it reaches the second discharge voltage.

[0072] Next, the process of constant-current charging with a current of 2C until the control voltage reaches 8.10V and constant-current discharging with a current of 2C until the control voltage reaches 5.0V was repeated 20 times each, alternating between the two. Hereafter, the above process will be referred to as the cycle charge / discharge process. The constant current discharge step in the cycle charge / discharge process corresponds to step ST101 in Figure 2, that is, the step of discharging the battery so that it does not fall below the first discharge voltage.

[0073] The charging process, discharging process, and cycle charge-discharge process were repeated three times in the order described. The discharge capacity was measured at the end of the discharging process and at the end of the constant current discharge performed in the cycle charge-discharge process.

[0074] Figure 5 shows the results of the discharge capacity measurement in the charge-discharge test. Figure 5 is a graph showing the results of the charge-discharge test. More specifically, Figure 5(a) is a graph showing the results of the charge-discharge test of the battery according to the example, Figure 5(b) is a graph showing the results of the charge-discharge test of the battery according to the comparative example, and Figure 5(c) is a graph showing the results of the charge-discharge test of the battery according to the example and the battery according to the comparative example superimposed.

[0075] As shown in Figures 5(a) and 5(c), the battery according to the embodiment gradually loses its discharge capacity with each repeated charge and discharge cycle. However, the discharge capacity of the battery according to the embodiment recovers after the discharge process is performed. As a result, the battery according to the embodiment maintains a discharge capacity of 1.2 mAh or more even at the end of the third cycle charging process.

[0076] In contrast, as shown in Figures 5(b) and 5(c), the battery capacity of the comparative example does not recover even after performing the discharge process. As a result, the battery in the comparative example was unable to maintain a discharge capacity of 1.2 mAh or more at the end of the third cycle charging process.

[0077] Thus, the battery according to this embodiment, that is, the battery prepared in the example, exhibits clearly superior charge-discharge cycle characteristics compared to the battery prepared in the comparative example.

[0078] Some or all of the above embodiments may also be described as follows, but are not limited to the following: (Note 1) A negative electrode layer containing a negative electrode active material, An alloy layer containing a lithium alloy, located between the negative electrode layer and the current collector, having an electrode potential higher than that of the negative electrode active material, A positive electrode layer containing a lithium compound as a positive electrode active material, battery. (Note 2) An electrode is formed by laminating an electrode, with the negative electrode layer and the alloy layer on one side of the current collector and the positive electrode layer on the other side of the current collector, via an electrolyte. The battery described in Appendix 1. (Note 3) A first current collector having the negative electrode layer and the alloy layer on both sides, A second current collector having the positive electrode layer on both sides, The first and second current collectors are stacked alternately with an electrolyte in between. The battery described in Appendix 1. (Note 4) The lithium alloy is an alloy of lithium with one or more metals selected from the group consisting of tin, aluminum, bismuth, indium, silver, and antimony. A battery as specified in any one of the appendices 1 to 3. (Note 5) The negative electrode active material is LiC6, Li 4.4 Si and Li4Ti5O 12 It is one or more species selected from a larger group. A battery as specified in any one of the appendices 1 to 4. (Note 6) The aforementioned lithium alloy is an alloy of tin and lithium. The negative electrode active material is silicon. A battery as specified in any one of the appendices 1 to 5. (Note 7) A negative electrode layer containing a negative electrode active material, An alloy layer containing a lithium alloy, located between the negative electrode layer and the current collector, and having an electrode potential higher than that of the negative electrode active material, is provided on one side of the current collector. A positive electrode layer containing a lithium compound as a positive electrode active material is provided on the other side of the current collector. electrode. (Note 8) A negative electrode layer containing a negative electrode active material, The current collector is provided with an alloy layer on both sides, which is located between the negative electrode layer and the current collector and contains a lithium alloy whose electrode potential is higher than that of the negative electrode active material. electrode. (Note 9) For a battery described in any one of the appendices 1 to 6, a first discharge voltage and a second voltage that is smaller than the first voltage value are determined. If the battery capacity of the battery is greater than a predetermined value, the battery is discharged so that the discharge voltage of the battery does not fall below the first discharge voltage. If the battery capacity of the battery is less than a predetermined value, the battery is discharged until its discharge voltage reaches a second discharge voltage. Battery usage instructions. (Note 10) A process for forming a metal layer containing metal, A process for forming a negative electrode layer containing a negative electrode active material, A process for forming a positive electrode layer containing a lithium compound as the positive electrode active material, A step of laminating the metal layer, the negative electrode layer, and the positive electrode layer, The process includes a step of applying an electric current to the stacked metal layer, the negative electrode layer, and the positive electrode layer to form an alloy of the metal and lithium in the metal layer. Battery manufacturing method.

[0079] Although the present invention has been described above in reference to the embodiments described above, the present invention is not limited to the configuration of the embodiments described above, and of course includes various modifications, alterations, and combinations that can be made by a person skilled in the art within the scope of the claims of the present patent application. [Explanation of symbols]

[0080] 1. 1M battery, C current collector, PL positive electrode layer, NL negative electrode layer, EL electrolyte layer AL alloy layer, ML metal layer

Claims

1. A method for using a battery comprising: a negative electrode layer containing a negative electrode active material; an alloy layer located between the negative electrode layer and a current collector, the alloy layer containing a lithium alloy having an electrode potential higher than that of the negative electrode active material; and a positive electrode layer containing a lithium compound as a positive electrode active material, A first discharge voltage and a second voltage that is smaller than the first voltage value are determined for the aforementioned battery. The battery is discharged such that its discharge voltage does not fall below the first discharge voltage. If the battery capacity of the battery is less than a predetermined value, the battery is discharged until its discharge voltage reaches a second discharge voltage. Battery usage instructions.

2. The lithium alloy is an alloy of lithium with one or more metals selected from the group consisting of tin, aluminum, bismuth, indium, silver, and antimony. The method of using the battery according to claim 1.

3. The aforementioned lithium alloy is an alloy of tin and lithium. The negative electrode active material is silicon. The method of using the battery according to claim 2.

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