Battery

Abstract

A battery 1000 according to the present disclosure comprises a positive electrode 103, a negative electrode 101, and an electrolyte layer 102 positioned between the positive electrode 103 and the negative electrode 101. The positive electrode 103 has a positive electrode active material layer 106; and the positive electrode active material layer 106 has a transition metal element and oxo anions, and includes a compound capable of occluding and releasing lithium ions. The negative electrode 101 has a negative electrode current collector 100 and a negative electrode active material layer 104; and the negative electrode active material layer 104 includes an alloy containing Bi and Ni.

Description

Technical Field

[0001] This disclosure relates to batteries.

Background Art

[0002] In recent years, in lithium secondary batteries that have been actively researched and developed, battery characteristics such as weight energy density, volume energy density, charge-discharge voltage, charge-discharge cycle life characteristics, and storage characteristics are greatly influenced by the electrodes used. Therefore, by improving the electrode active material, improvement of battery characteristics has been attempted.

[0003]

[0004]

[0005]

Prior Art Documents

[0006]

Patent Documents

Patent Document 1

Patent Document 2

[0007]

Non-Patent Documents

Non-Patent Document 1

[0008] This disclosure provides a battery having a configuration suitable for expanding the plateau region. [Means for solving the problem]

[0009] The battery disclosed herein is Positive electrode and, The negative electrode and, An electrolyte layer located between the positive electrode and the negative electrode, Equipped with, The positive electrode has a positive electrode active material layer, The positive electrode active material layer contains a compound having a transition metal element and an oxoanion, and capable of intercalating and releasing lithium ions. The negative electrode comprises a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer comprises an alloy containing Bi and Ni. [Effects of the Invention]

[0010] According to this disclosure, it is possible to provide a battery having a configuration suitable for expanding the plateau region. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic cross-sectional view showing an example of the battery configuration according to the present disclosure. [Figure 2] Figure 2 is a graph showing an example of the X-ray diffraction pattern of a negative electrode active material layer composed of a BiNi thin film fabricated on nickel foil. [Figure 3] Figure 3 is a schematic partially enlarged cross-sectional view showing a modified example of the negative electrode of a battery according to the present disclosure. [Figure 4] Figure 4 is a schematic cross-sectional view showing a modified example of the battery according to the present disclosure. [Figure 5] Figure 5 shows the results of a charge-discharge test of the test cell according to Example 1, and is a graph showing the voltage during discharge and the discharge capacity per unit mass of positive electrode active material. [Figure 6] Figure 6 shows the results of a charge-discharge test of the test cell according to Example 2, and is a graph showing the voltage during discharge and the discharge capacity per unit mass of positive electrode active material. [Figure 7] Figure 7 shows the results of a charge-discharge test of the test cell according to Reference Example 1, and is a graph showing the voltage during discharge and the discharge capacity per unit mass of positive electrode active material. [Figure 8] Figure 8 shows the results of a charge-discharge test of the test cell according to Reference Example 2, and is a graph showing the voltage during discharge and the discharge capacity per unit mass of positive electrode active material. [Figure 9] Figure 9 shows the results of a charge-discharge test of the test cell according to Reference Example 3, and is a graph showing the voltage during discharge and the discharge capacity per unit mass of positive electrode active material. [Modes for carrying out the invention]

[0012] (Knowledge that forms the basis of this disclosure) As described in the [Background Technology] section, improvements in lithium secondary batteries are being made to battery characteristics by improving the electrode active material.

[0013] When lithium metal is used as the negative electrode active material, a lithium secondary battery with high energy density per unit weight and per unit volume can be obtained. However, in lithium secondary batteries with this configuration, lithium deposits in a dendrite-like manner during charging. Because some of the deposited lithium metal reacts with the electrolyte, there is a problem of low charge-discharge efficiency and poor cycle characteristics.

[0014] In response to this, the use of carbon, particularly graphite, as the negative electrode has been proposed. In a negative electrode using carbon, charging and discharging occur through the insertion and removal of lithium from the carbon. In a negative electrode with such a configuration, lithium metal does not precipitate in a dendrite-like manner due to the charge-discharge mechanism. Furthermore, in lithium secondary batteries employing a negative electrode with such a configuration, the reaction is topotactic, resulting in excellent reversibility and nearly 100% charge-discharge efficiency. For these reasons, lithium secondary batteries employing negative electrodes made of carbon, particularly graphite, have been put into practical use. However, the theoretical capacity density of graphite is 372 mAh / g, which is about 1 / 10 of the theoretical capacity density of lithium metal, which is 3884 mAh / g. Therefore, the active material capacity density of a negative electrode using graphite is low. Moreover, since the actual capacity density of graphite has almost reached its theoretical capacity density, there is a limit to how high a capacity can be achieved with a negative electrode using graphite.

[0015] In response to these issues, lithium-ion secondary batteries using aluminum, silicon, tin, etc., which electrochemically alloy with lithium during charging, have long been proposed. The capacity density of metals that alloy with lithium is significantly higher than that of graphite. In particular, the theoretical capacity density of silicon is high. Therefore, electrodes using aluminum, silicon, tin, etc., which alloy with lithium, are promising as negative electrodes for batteries exhibiting high capacity, and various secondary batteries using these as negative electrodes have been proposed (Patent Document 1).

[0016] However, negative electrodes using metals that alloy with lithium, as described above, expand when they absorb lithium and contract when they release lithium. When such expansion and contraction are repeated during charging and discharging, the alloy itself, which is the electrode active material, becomes pulverized by charging and discharging, degrading the current collection characteristics of the negative electrode, and thus sufficient cycle characteristics have not been obtained. Several attempts have been made to improve these shortcomings. For example, attempts have been made to deposit silicon on a roughened current collector by sputtering or vapor deposition, or to deposit tin by electroplating (Patent Document 2). In this attempt, the active material, i.e., the metal that alloys with lithium, is in close contact with the current collector as a thin film, so even when the negative electrode repeatedly expands and contracts due to the absorption and release of lithium, the current collection performance hardly deteriorates.

[0017] However, as mentioned above, forming the active material by sputtering or vapor deposition results in high manufacturing costs, making it impractical. Forming the active material by electroplating, which is inexpensive, is more practical, but silicon is extremely difficult to electroplat. Furthermore, tin, which is easily electroplated, has poor discharge flatness, making it unsuitable for use as a battery electrode.

[0018] Another metal that alloys with lithium is bismuth (Bi). Bi forms compounds called LiBi and Li3Bi with lithium (Li). The potentials of LiBi and Li3Bi are almost the same. On the other hand, tin, which has poor discharge flatness, forms several types of compounds with lithium, and the potentials of each compound are quite different from each other. In other words, Bi does not have the property of having a large difference in potential between the multiple types of compounds it forms with lithium, as tin does. For this reason, electrodes containing Bi as an active material have a flat potential and therefore excellent discharge flatness. Consequently, electrodes containing Bi as an active material are considered suitable as electrodes for batteries.

[0019] However, Bi has poor malleability and ductility, making it difficult to manufacture in the form of metal sheets or foils, and the resulting form is small spheres or powder. For this reason, electrodes containing Bi as an active material have been investigated that are manufactured by coating Bi powder onto a current collector. However, electrodes manufactured using such Bi powder have not been able to obtain sufficient cycle characteristics because they become pulverized after repeated charging and discharging, resulting in deterioration of current collection characteristics. For example, Non-Patent Literature 1 describes the manufacture of an electrode containing Bi as an active material using Bi powder and PVdF (polyvinylidene fluoride) or PI (polyimide) as a binder. Non-Patent Literature 1 describes the charging and discharging of a battery manufactured using this electrode. However, the results of the initial charge-discharge curve and cycle characteristics of the manufactured electrode are both very poor. Although measured at a very low rate equivalent to 0.042 IT, the initial charge-discharge efficiency is low and the cycle degradation is severe, making it unsuitable for practical use. Regarding this cyclic degradation, Non-Patent Literature 1 suggests that as the Bi active material expands during Li insertion and contracts during Li desorption, the active material becomes smaller, preventing electron conduction paths from being formed, and thus a decrease in capacity occurs.

[0020] As described above, the inventors focused on Bi, which does not exhibit a large difference in potential between the various compounds formed with Li and has excellent discharge flatness, and diligently investigated batteries that could improve cycle characteristics. As a result, the inventors arrived at a new technological concept in which the cycle characteristics of a battery can be improved when an alloy containing Bi and Ni is used as the active material.

[0021] The inventors of the present invention conducted further detailed studies on batteries in which an alloy containing Bi and Ni is used as the active material. Specifically, they investigated the selection of an appropriate positive electrode material when an alloy containing Bi and Ni is used as the negative electrode active material.

[0022] Layered or spinel-type lithium metal composite oxides are among the cathode materials that are being actively researched and developed. Lithium-ion secondary batteries using such lithium metal composite oxides as cathode materials can achieve high voltages of around 4V. For this reason, lithium-ion secondary batteries using lithium metal composite oxides as cathode materials are being increasingly put into practical use as batteries with high energy density.

[0023] Currently, the cathode materials used in lithium-ion secondary batteries include lithium cobalt composite oxide (LiCoO2), which is relatively easy to synthesize; lithium nickel composite oxide (LiNiO2), which uses nickel that is cheaper than cobalt; and lithium nickel manganese composite oxide (LiNi 0.5 Mn 0.5 Lithium manganese composite oxide (LiMn2O4) using manganese, lithium nickel cobalt manganese composite oxide (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2), Lithium nickel cobalt aluminum composite oxide (LiNi 1 / 3 Co 1 / 3 Al 1 / 3 Lithium composite oxides such as O2 have been proposed.

[0024] However, as the inventors continued their investigation, they found that when the positive electrode material exemplified above is combined with a negative electrode material in which an alloy containing Bi and Ni is used as the negative electrode active material, there is room for improvement in the discharge flatness of the resulting battery.

[0025] As a result of diligent research, the present inventors have discovered that by using a positive electrode containing a specific positive electrode active material in an electrode containing an alloy containing Bi and Ni as the negative electrode active material, the discharge flatness of the battery can be improved, that is, the plateau region of the battery voltage can be extended, and thus have completed this disclosure.

[0026] A wide battery voltage plateau is a significant advantage in that it facilitates the design of energy-efficient devices when incorporating batteries.

[0027] (Summary of an aspect according to the present disclosure) The battery according to the first aspect of the present disclosure is a positive electrode, a negative electrode, an electrolyte layer positioned between the positive electrode and the negative electrode, and includes The positive electrode has a positive electrode active material layer, The positive electrode active material layer includes a compound having a transition metal element and an oxoanion and capable of occluding and releasing lithium ions, The negative electrode has a negative electrode current collector and a negative electrode active material layer, The negative electrode active material layer includes an alloy containing Bi and Ni.

[0028] According to the first aspect, a battery having a configuration suitable for expanding the plateau region can be provided.

[0029] In the second aspect, for example, in the battery according to the first aspect, the oxoanion may contain B, Si, P, or S.

[0030] According to the battery according to the second aspect, a wider plateau region can be realized.

[0031] In the third aspect, for example, in the battery according to the second aspect, the oxoanion is BO3 3- , SiO4 4- , PO4 3- , P2O7 4- , or SO4 2- and may be.

[0032] According to the battery according to the third aspect, a wider plateau region can be realized.

[0033] In the fourth aspect, for example, in the battery according to any one of the first to third aspects, the electrochemical reaction between the compound and lithium may include a two-phase coexistence reaction.

[0034] According to the battery according to the fourth aspect, a wider plateau region can be realized.

[0035] In the fifth embodiment, for example, in a battery according to any one of the first to fourth embodiments, the positive electrode active material layer may contain the compound as the main component of the positive electrode active material.

[0036] According to the fifth embodiment of the battery, a wider plateau region can be achieved.

[0037] In the sixth embodiment, for example, in a battery according to any one of the first to fifth embodiments, the compound may have an olivine structure.

[0038] According to the battery of the sixth embodiment, a wider plateau region can be achieved.

[0039] In the seventh embodiment, for example, in a battery according to any one of the first to sixth embodiments, the transition metal element may be at least one selected from the group consisting of Fe, Mn, Co, and Ni.

[0040] According to the battery of the seventh embodiment, a wider plateau region can be achieved.

[0041] In the eighth embodiment, for example, in a battery according to any one of the first to seventh embodiments, the positive electrode active material layer may contain LiFePO4.

[0042] According to the battery of the eighth embodiment, a wider plateau region can be achieved.

[0043] In the ninth embodiment, for example, in a battery according to any one of the first to eighth embodiments, the negative electrode active material layer may contain BiNi.

[0044] According to the ninth embodiment, a battery with a wide plateau region and improved volumetric energy density can be realized.

[0045] In the tenth embodiment, for example, the battery according to the ninth embodiment may contain BiNi as the main component of the negative electrode active material.

[0046] According to the tenth embodiment, a battery with a wider plateau region and improved volumetric energy density can be realized.

[0047] In the 11th embodiment, for example, in the battery according to the 9th or 10th embodiment, the BiNi may have a monoclinic crystal structure in which the space group belongs to C2 / m.

[0048] According to the battery of the 11th embodiment, in addition to a wide plateau region and improved volumetric energy density, the battery's cycle characteristics can also be improved.

[0049] In the twelfth embodiment, for example, a battery according to any one of the first to eleventh embodiments may include at least one selected from the group consisting of LiBi and Li3Bi.

[0050] According to the twelfth embodiment, a battery with a wider plateau region and improved volumetric energy density can be realized.

[0051] In the 13th embodiment, for example, in a battery according to any one of the first to 12 embodiments, the negative electrode active material layer may not contain a solid electrolyte.

[0052] According to the 13th embodiment, a battery with a wider plateau region and improved volumetric energy density can be realized.

[0053] In the 14th embodiment, for example, in a battery according to any one of the first to 13 embodiments, in the X-ray diffraction pattern of the negative electrode active material layer obtained by surface X-ray diffraction measurement using Cu-Kα rays, Let I(1) be the height intensity of the maximum peak present in the diffraction angle range 2θ from 29° to 31°. When I(2) is the height intensity of the maximum peak that exists in the diffraction angle range 2θ from 41° to 43°, The ratio of I(2) to I(1), I(2) / I(1), may be 0.28 or less.

[0054] The battery according to the 14th embodiment can have improved cycle characteristics and increased capacity, in addition to a wide plateau region and improved volumetric energy density.

[0055] In the 15th embodiment, for example, in a battery according to any one of the first to 14th embodiments, the negative electrode current collector may include at least one selected from the group consisting of Cu and Ni.

[0056] According to the 15th embodiment, a battery with a wider plateau region and improved volumetric energy density can be realized.

[0057] In the 16th embodiment, for example, in a battery according to any one of the first to 15 embodiments, the negative electrode active material layer may be a heat-treated plated layer.

[0058] The battery according to the 16th embodiment can have improved cycle characteristics and increased capacity, in addition to a wide plateau region and improved volumetric energy density.

[0059] In the 17th embodiment, for example, in a battery according to any one of the first to 16 embodiments, the electrolyte layer may be a solid electrolyte layer.

[0060] The battery according to the 17th embodiment can have improved cycle characteristics in addition to a wide plateau region and increased volumetric energy density.

[0061] In the eighteenth aspect of this disclosure, for example, in the battery according to the seventeenth aspect, the solid electrolyte layer may include a halogen solid electrolyte, and the halogen solid electrolyte may not contain sulfur.

[0062] According to the 18th embodiment, a battery with a wider plateau region and improved volumetric energy density can be realized.

[0063] In a 19th aspect of this disclosure, for example, in the battery according to the 17th aspect, the solid electrolyte layer may include a sulfide solid electrolyte.

[0064] According to the 19th embodiment, a battery with a wider plateau region and improved volumetric energy density can be realized.

[0065] In the 20th aspect of this disclosure, for example, in a battery according to any one of the first to 16th aspects, the electrolyte layer may include an electrolyte solution.

[0066] According to the 20th embodiment, a battery can be realized with a wider plateau region and improved volumetric energy density.

[0067] (Embodiments of the present disclosure) Embodiments of this disclosure will be described below with reference to the drawings. The following descriptions are general or specific examples. The numerical values, compositions, shapes, film thicknesses, electrical properties, and secondary battery structures shown below are examples and are not intended to limit this disclosure.

[0068] Figure 1 is a schematic cross-sectional view showing an example of the configuration of a battery 1000 according to an embodiment of this disclosure.

[0069] The battery 1000 comprises a negative electrode 101, a positive electrode 103, and an electrolyte layer 102 located between the negative electrode 101 and the positive electrode 103.

[0070] The negative electrode 101 comprises a negative electrode current collector 100 and a negative electrode active material layer 104. The negative electrode active material layer 104 is located between the negative electrode current collector 100 and the electrolyte layer 102. The negative electrode active material layer 104 contains an alloy containing Bi and Ni.

[0071] The positive electrode 103 has a positive electrode active material layer 106. The positive electrode active material layer 106 contains a compound that has a transition metal element and an oxoanion, and is capable of intercalating and releasing lithium ions.

[0072] As shown in Figure 1, the positive electrode 103 may include a positive electrode current collector 105 that is in contact with the positive electrode active material layer 106. By providing the positive electrode current collector 105, electricity can be extracted from the battery 1000 with high efficiency.

[0073] Battery 1000 contains an alloy containing Bi and Ni as the negative electrode active material, and a compound having a transition metal element and an oxoanion, and capable of intercalating and releasing lithium ions, as the positive electrode active material. This configuration allows battery 1000 to improve discharge flatness, i.e., to broaden the plateau region of the battery voltage.

[0074] In battery 1000, the electrolyte layer 102 is a solid electrolyte layer. Therefore, even if the negative electrode active material layer 104, which contains an alloy with Bi and Ni as the negative electrode active material, repeatedly expands and contracts due to charging and discharging, the electrolyte does not enter the negative electrode active material layer 104. As a result, the reduction of electron conduction paths within the negative electrode active material layer 104 due to repeated charging and discharging is suppressed. Consequently, battery 1000 is less susceptible to a decrease in the current collecting ability of the negative electrode active material layer 104 due to charging and discharging, and can therefore have good cycle characteristics.

[0075] Battery 1000 is, for example, a lithium secondary battery. During charging and discharging of battery 1000, the metal ions intercepted and released in the negative electrode active material layer 104 of the negative electrode 101 and the positive electrode active material layer 106 of the positive electrode 103 are lithium ions.

[0076] The negative electrode active material layer 104 contains Bi and Ni as an alloy, for example, BiNi. The negative electrode active material layer 104 may contain BiNi as the main component. Here, "the negative electrode active material layer 104 contains BiNi as the main component" is defined as "the BiNi content in the negative electrode active material layer 104 is 50% by mass or more." The BiNi content in the negative electrode active material layer 104 can be determined, for example, by confirming that Bi and Ni are contained in the negative electrode active material layer 104 by elemental analysis using EDX (energy-dispersive X-ray spectroscopy), and then calculating the ratio of the contained compounds by performing Rietveld analysis on the X-ray diffraction results of the negative electrode active material layer 104.

[0077] With the above configuration, a battery 1000 can be obtained that has a wide voltage plateau region and improved volumetric energy density.

[0078] The BiNi contained in the negative electrode active material layer 104 may have a monoclinic crystal structure whose space group belongs to C2 / m.

[0079] With the above configuration, in addition to a wide plateau region and improved volumetric energy density, the battery's cycle characteristics can also be improved.

[0080] The negative electrode active material layer 104, which mainly contains BiNi, may be composed of, for example, BiNi formed in the form of a thin film (hereinafter referred to as "BiNi thin film").

[0081] In the X-ray diffraction pattern of the negative electrode active material layer 104 obtained by surface X-ray diffraction measurement using Cu-Kα rays, when the height intensity of the maximum peak located in the diffraction angle 2θ range of 29° to 31° is defined as I(1), and the height intensity of the maximum peak located in the diffraction angle 2θ range of 41° to 43° is defined as I(2), the ratio of I(2) to I(1), I(2) / I(1), may be 0.28 or less.

[0082] Here, the maximum peak in the X-ray diffraction pattern within the diffraction angle range of 2θ from 29° to 31° corresponds to the peak originating from the (2,2,1) plane of the intermetallic compound BiNi. Similarly, the maximum peak in the X-ray diffraction pattern within the diffraction angle range of 2θ from 41° to 43° corresponds to the peak originating from the (2,2,3) plane of the intermetallic compound BiNi. A peak intensity ratio I(2) / I(1) of 0.28 or less means that the proportion of the (2,2,3) plane to the (2,2,1) plane of BiNi, which has a monoclinic crystal structure with space group C2 / m, is low on the surface of the negative electrode active material layer 104. In other words, it means that the orientation of the (2,2,1) plane is stronger on the surface of the negative electrode active material layer 104. A negative electrode active material layer 104 with such orientation in the crystal structure of BiNi on its surface can have high adhesion to the negative electrode current collector 100. Therefore, because the negative electrode active material layer 104 has such surface orientation, even if the negative electrode active material layer 104 repeatedly expands and contracts due to charging and discharging, a decrease in current collection performance is less likely to occur. Accordingly, the battery 1000 of this disclosure can have improved cycle characteristics and increased capacity, in addition to a wide plateau region and improved volumetric energy density.

[0083] The X-ray diffraction pattern of the active material layer 104 can be obtained by X-ray diffraction measurements using the θ-2θ method with Cu-Kα rays having wavelengths of 1.5405 Å and 1.5444 Å, i.e., wavelengths of 0.15405 nm and 0.15444 nm.

[0084] The diffraction angle of a peak in an X-ray diffraction pattern is defined as the angle that shows the maximum intensity of the peak-shaped portion where the signal-to-noise ratio (i.e., the ratio of signal S to background noise N) is 1.3 or greater and the full width at half maximum (FWHM) is 10° or less. FWHM is the maximum intensity of the X-ray diffraction peak. MAX When the intensity is I MAX This refers to the width represented by the difference between two diffraction angles that are half the value of the given value.

[0085] The negative electrode active material layer 104, which is composed of a BiNi thin film containing BiNi as the main component and satisfying the above-mentioned surface orientation properties, can be manufactured, for example, by electroplating. A method for manufacturing the negative electrode 101 by manufacturing the negative electrode active material layer 104 by electroplating is as follows, for example.

[0086] First, the substrate for electroplating is prepared. In the case of the negative electrode 101, for example, the negative electrode current collector 100 serves as the substrate. For example, a current collector containing Ni is prepared as the negative electrode current collector 100. The manufacturing method of the negative electrode 101 is, for example, A Bi plating layer is fabricated on a current collector containing Ni by electroplating, The current collector and the Bi plating layer are heated to diffuse the Ni contained in the current collector into the Bi plating layer, thereby obtaining an electrode in which an active material layer containing BiNi is formed on the current collector. This includes the Bi plating layer. The heating temperature for the Bi plating layer is, for example, 250°C or higher, and may also be 350°C or higher.

[0087] The manufacturing method for the negative electrode 101 will be explained in more detail.

[0088] First, prepare the substrate for electroplating. In the case of the negative electrode 101, for example, the negative electrode current collector 100 will be the substrate. As an example, nickel foil will be prepared as the negative electrode current collector 100. After pre-degreasing the nickel foil with an organic solvent, one side will be masked and the foil will be degreased by immersion in an acidic solvent to activate the surface of the nickel foil. The activated nickel foil will be connected to a power supply so that current can be applied. The nickel foil connected to the power supply will be immersed in a bismuth plating bath. As a bismuth plating bath, for example, Bi 3+An organic acid bath containing ions and organic acids is used. Then, by applying a current to the nickel foil while controlling the current density and application time, Bi is electroplated onto the unmasked nickel foil surface. After electroplating, the nickel foil is recovered from the plating bath, the masking is removed, and then it is washed with pure water and dried. By these methods, a Bi plating layer is created on the nickel foil surface. The bismuth plating bath used to create the Bi plating layer is not particularly limited and can be appropriately selected from known bismuth plating baths capable of depositing a thin film of elemental Bi. In the bismuth plating bath, an organic sulfonic acid bath, a gluconic acid and ethylenediaminetetraacetic acid (EDTA) bath, or a citric acid and EDTA bath may be used as the organic acid bath. In addition, a sulfuric acid bath may be used as the bismuth plating bath. Additives may also be added to the bismuth plating bath.

[0089] Table 1 shows the target thickness of the Bi-plated layer produced by electroplating Bi, and the actual thickness of the Bi-plated layer produced.

[0090] Samples of the Bi-plated layer were prepared using the same method as in Example 1 described below. Specifically, the current application time to the nickel foil, which was the plating substrate, was adjusted to aim for a plating thickness of 5 μm, and samples were prepared. The thickness of the obtained Bi-plated layer was measured using a Seiko Instruments SEA6000VX X-ray fluorescence spectrometer. The average thickness of the Bi layer in the five samples was 5.7 μm, 5.1 μm, 5.1 μm, 5.7 μm, and 5.8 μm.

[0091] [Table 1]

[0092] Next, the nickel foil and the Bi plating layer formed on the nickel foil are heated. This heat treatment allows for the solid-phase diffusion of Ni from the nickel foil to the Bi plating layer, thereby creating an active material layer composed of a BiNi thin film. Here, a sample of nickel foil electroplated with Bi is subjected to a heat treatment, for example, at a temperature of 250°C or higher in a non-oxidizing atmosphere for 30 minutes to less than 100 hours, which allows for the solid-phase diffusion of Ni from the nickel foil to the Bi plating layer, thereby creating an active material layer composed of a BiNi thin film.

[0093] For the above sample, in which Bi was electroplated onto nickel foil to a thickness of approximately 5 μm, an active material layer composed of a BiNi thin film was fabricated by heat treatment at 400°C for 60 hours in an argon atmosphere. Furthermore, the surface structure of the fabricated BiNi thin film active material layer was analyzed by surface X-ray diffraction measurement.

[0094] Figure 2 is a graph showing an example of the X-ray diffraction pattern of a negative electrode active material layer composed of a BiNi thin film fabricated on nickel foil. The X-ray diffraction pattern was measured using the θ-2θ method with Cu-Kα rays at wavelengths of 1.5405 Å and 1.5444 Å, using an X-ray diffractometer (RIGAKU, MiNi Flex) from the surface of the active material layer, i.e., in the thickness direction of the active material layer 104. From the X-ray diffraction pattern shown in Figure 2, the phases of BiNi, whose space group is assigned to C2 / m as a crystal structure, and the nickel foil as a current collector and Ni contained in the active material layer were identified.

[0095] In the X-ray diffraction pattern of the negative electrode active material layer obtained by surface X-ray diffraction measurement using Cu-Kα rays, as shown in Figure 2, the intensity ratio I(2) / I(1) of the maximum peak height intensity I(1) located in the diffraction angle 2θ range of 29° to 31° and the maximum peak height intensity I(2) located in the diffraction angle 2θ range of 41° to 43° was calculated, and the ratio I(2) / I(1) was 0.28 or less.

[0096] From the X-ray diffraction pattern results shown above, it can be seen that on the surface of the negative electrode active material layer 104, which was fabricated by electroplating Bi onto a negative electrode current collector 100 containing Ni to create a Bi plating layer, and then heating the Bi plating layer on the negative electrode current collector 100 together with the negative electrode current collector 100, the ratio of (2,2,3) planes to (2,2,1) planes of BiNi, which has a monoclinic crystal structure whose space group belongs to C2 / m, is low. In other words, it can be seen that the orientation of the (2,2,1) plane is strong on the surface of the negative electrode active material layer 104. From this, it was found that by fabricating a Bi plating layer on a negative electrode current collector containing Ni, and then heat-treating the resulting Bi plating layer on the Ni-containing negative electrode current collector, it is possible to orient BiNi, which has a monoclinic crystal structure whose space group belongs to C2 / m, so that the (2,2,1) plane becomes the surface. A negative electrode equipped with a BiNi thin film having such orientation as the negative electrode active material layer can further improve the battery's cycle characteristics in addition to a wide plateau region and improved volumetric energy density.

[0097] The components of the battery 1000 in this embodiment will be described in more detail below.

[0098] [Negative electrode] As described above, the negative electrode 101 has a negative electrode current collector 100 and a negative electrode active material layer 104. The composition of the negative electrode active material layer 104 is as described above. Therefore, the negative electrode active material layer 104 includes an alloy containing Bi and Ni as a negative electrode active material having the property of intercalating and releasing lithium ions. The negative electrode active material layer 104 includes, for example, BiNi as the negative electrode active material. The negative electrode active material layer 104 may also include BiNi having a crystal structure in which the space group belongs to C2 / m.

[0099] Bi is a metallic element that alloys with lithium. On the other hand, Ni does not alloy with lithium, so it is presumed that alloys containing Ni reduce the load on the crystal structure of the negative electrode active material during the desorption and insertion of lithium atoms during charging and discharging, thereby suppressing the decrease in the battery's capacity retention rate. When BiNi functions as the negative electrode active material, lithium is intercalated when Bi forms an alloy with lithium during charging. That is, a lithium bismuth alloy is generated in the negative electrode active material layer 104 when the battery 1000 is charged. The generated lithium bismuth alloy includes, for example, at least one selected from the group consisting of LiBi and Li3Bi. That is, when the battery 1000 is charged, the active material layer 104 includes, for example, at least one selected from the group consisting of LiBi and Li3Bi. When the battery 1000 is discharged, lithium is released from the lithium bismuth alloy, and the lithium bismuth alloy returns to BiNi.

[0100] BiNi, used as the negative electrode active material, reacts during charging and discharging of the battery 1000, for example, as follows. Note that the following example of reactions is for the case where the lithium bismuth alloy produced during charging is Li3Bi. Charging: BiNi+3Li + +3e - →Li3Bi+Ni Discharge: Li3Bi + Ni → BiNi + 3Li + +3e -

[0101] The negative electrode active material layer 104 may contain substantially only BiNi as the negative electrode active material. In this case, the battery 1000 can have improved capacity and improved cycle characteristics, in addition to a wide plateau region and improved volumetric energy density. Note that "the negative electrode active material layer 104 contains substantially only BiNi as the negative electrode active material" means, for example, that the negative electrode active material contained in the negative electrode active material layer 104 contains 1% by mass or less of other negative electrode active materials other than BiNi. The negative electrode active material layer 104 may contain only BiNi as the negative electrode active material.

[0102] The negative electrode active material layer 104 does not necessarily contain a solid electrolyte. For example, the negative electrode active material layer 104 may be a layer made of BiNi and / or a lithium bismuth alloy and nickel generated during charging.

[0103] The negative electrode active material layer 104 may be disposed in direct contact with the surface of the negative electrode current collector 100.

[0104] The negative electrode active material layer 104 may be in the form of a thin film.

[0105] The negative electrode active material layer 104 may be a heat-treated plating layer. The negative electrode active material layer 104 may be a heat-treated plating layer provided in direct contact with the surface of the negative electrode current collector 100. That is, as described above, the negative electrode active material layer 104 may be a layer formed by heat-treating a Bi plating layer formed on the Ni-containing negative electrode current collector 100.

[0106] If the negative electrode active material layer 104 is a heat-treated plating layer that is in direct contact with the surface of the negative electrode current collector 100, the negative electrode active material layer 104 adheres firmly to the negative electrode current collector 100. This further suppresses the deterioration of the current collection characteristics of the negative electrode 101 that occurs when the negative electrode active material layer 104 repeatedly expands and contracts. Therefore, the cycle characteristics of the battery 1000 are further improved. Furthermore, if the negative electrode active material layer 104 is a heat-treated plating layer, the negative electrode active material layer 104 contains a high density of Bi, which alloys with lithium, thus enabling even higher capacity.

[0107] The negative electrode active material layer 104 may contain materials other than alloys containing Bi and Ni.

[0108] The negative electrode active material layer 104 may further contain a conductive material.

[0109] Examples of conductive materials include carbon materials, metals, inorganic compounds, and conductive polymers. Examples of carbon materials include graphite, acetylene black, carbon black, Ketjenblack, carbon whiskers, needle coke, and carbon fibers. Examples of graphite include natural graphite and artificial graphite. Examples of natural graphite include lump graphite and flake graphite. Examples of metals include copper, nickel, aluminum, silver, and gold. Examples of inorganic compounds include tungsten carbide, titanium carbide, tantalum carbide, molybdenum carbide, titanium boride, and titanium nitride. These materials may be used individually or in combination.

[0110] The negative electrode active material layer 104 may further contain a binder.

[0111] Examples of binders include fluororesins, thermoplastics, ethylene propylene diene monomer (EPDM) rubber, sulfonated EPDM rubber, and natural butyl rubber (NBR). Examples of fluororesins include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluororubber. Examples of thermoplastics include polypropylene and polyethylene. These materials may be used individually or in combination.

[0112] The thickness of the negative electrode active material layer 104 is not particularly limited and may be, for example, 1 μm or more and 100 μm or less.

[0113] The material of the negative electrode current collector 100 is, for example, a single metal or alloy. More specifically, it may be a single metal or alloy containing at least one selected from the group consisting of copper, chromium, nickel, titanium, platinum, gold, aluminum, tungsten, iron, and molybdenum. The negative electrode current collector 100 may also be stainless steel.

[0114] The negative electrode current collector 100 may include at least one selected from the group consisting of copper (Cu) and nickel (Ni).

[0115] The negative electrode current collector 100 may be in the form of a plate or foil. From the viewpoint of easily ensuring high conductivity, the negative electrode current collector 100 may be a metal foil, or a metal foil containing nickel. Examples of nickel-containing metal foils include nickel foil and nickel alloy foil. The nickel content in the metal foil may be 50% by mass or more, or 80% by mass or more. In particular, the metal foil may be a nickel foil containing substantially only nickel as the metal. The negative electrode current collector 100 may be a metal foil formed of a metal other than nickel, with a Ni layer, such as a Ni plating layer, formed on its surface.

[0116] The negative electrode current collector 100 may be a multilayer film.

[0117] Figure 3 is a schematic partially enlarged cross-sectional view showing a modified example of the negative electrode of a battery according to an embodiment of the present disclosure. The negative electrode of a battery according to an embodiment of the present disclosure may be a negative electrode 109 having a porous substrate 107 and a negative electrode active material layer 108 located on the surface of the substrate 107, as shown in Figure 3. The negative electrode active material layer 108 contains an alloy containing Bi and Ni, similar to the negative electrode active material layer 104 described above. The negative electrode active material layer 108 contains, for example, BiNi as the alloy containing Bi and Ni. In a negative electrode 109 having such a configuration, the porous substrate 107 is, for example, conductive. In this case, the substrate 107 can function as a current collector of the negative electrode 109. The negative electrode 109 may further have a negative electrode current collector (not shown) made of, for example, a plate-shaped or foil-shaped conductor. In this case, for example, the plate-shaped or foil-shaped negative electrode current collector and the substrate 107 function as current collectors of the negative electrode. A porous body refers to a structure having multiple pores, including open pores that open to the outside. Examples of porous bodies in this specification include meshes and porous structures. A porous structure is a structure composed of a porous material having multiple pores, and the size of the pores is not particularly limited. An example of a porous structure is a foam. A porous structure may also be a three-dimensional mesh structure in which the pores are in communication with each other. In this specification, "pore" includes both those that are filled with, for example, an active material layer and those that are not. That is, even those that are filled with, for example, an active material layer are considered "pores".

[0118] [Positive electrode] The positive electrode 103 has a positive electrode active material layer 106. The positive electrode active material layer 106 contains a material capable of intercalating and releasing metal ions such as lithium ions. This material is, for example, a positive electrode active material.

[0119] The positive electrode active material layer 106 contains a compound as the positive electrode active material that has a transition metal element and an oxoanion, and is capable of intercalating and releasing lithium ions.

[0120] By using a positive electrode active material containing the above-mentioned compounds in combination with a negative electrode active material containing an alloy containing Bi and Ni, the battery 1000 of this embodiment can broaden the plateau region of the battery voltage.

[0121] The electrochemical reaction between the above compound and lithium includes, for example, a two-phase coexistence reaction. By using a positive electrode active material containing such a compound in combination with a negative electrode active material containing an alloy containing Bi and Ni, the battery 1000 of this embodiment can further extend the plateau region of the battery voltage.

[0122] It is already known that compounds that involve a two-phase coexistence reaction in their electrochemical reaction with lithium can be used as positive electrode active materials for lithium secondary batteries.

[0123] For example, lithium iron phosphate (LiFePO4), which has an olivine structure, is known to undergo a two-phase coexistence reaction between LiFePO4 and FePO4 when charged and discharged by Li-ion insertion and deinsertion (Non-Patent Literature 2).

[0124] Furthermore, when lithium iron borate (LiFeBO3) is charged and discharged by the insertion and removal of Li ions, LiFeBO3 and Li 0.5 It is known that a two-phase coexistence reaction occurs between FeBO3 and the other phase (Non-Patent Literature 2).

[0125] Furthermore, when lithium iron sulfate (Li2Fe(SO4)2) is charged and discharged by the insertion and removal of Li ions, if Li2Fe(SO4)2 is monoclinic, a two-phase coexistence reaction occurs between the two phases of Li2Fe(SO4)2 and Li2Fe(SO4)2, and if Li2Fe(SO4)2 is orthorhombic, Li2Fe(SO4)2 and Li2Fe(SO4)2 react together. 1.5 Two-phase coexistence reaction between Fe(SO4)2 and Li 1.5 It is known that a two-phase coexistence reaction occurs continuously between the two phases of Fe(SO4)2 and LiFe(SO4)2 (Non-Patent Document 3).

[0126] Furthermore, it is known that lithium manganese silicate (Li2MnSiO4) undergoes a two-phase coexistence reaction between Li2MnSiO4 and LiMnSiO4 when charged and discharged by Li ion insertion and deinsertion (Non-Patent Literature 4).

[0127] Therefore, in the battery according to this embodiment, the conventionally proposed known compounds described above can be used as compounds that have a transition metal element and an oxoanion, and whose electrochemical reaction with lithium involves a two-phase coexistence reaction.

[0128] The positive electrode active material layer 106 of the battery 1000 according to this embodiment may contain the above compound as its main component. Here, "main component" refers to the component that is present in the largest amount by mass.

[0129] In the above compound, the oxoanion may contain B, Si, P, or S. By using such a compound as a positive electrode active material, a broader plateau region can be achieved.

[0130] In the above compound, the oxoanion is BO3 3- SiO4 4- , PO4 3- P2O7 4- , or SO4 2- This may also be the case. By using such compounds as positive electrode active materials, a wider plateau region can be achieved.

[0131] In the above compound, the transition metal element may be at least one selected from the group consisting of Fe, Mn, Co, and Ni. By using such a compound as a positive electrode active material, a broader plateau region can be achieved.

[0132] In the above compound, the transition metal element may be at least one selected from the group consisting of Fe and Mn. The transition metal element may contain Fe, or it may be Fe. By using such a compound as a positive electrode active material, a wider plateau region can be achieved.

[0133] The above-mentioned compounds may have an olivine structure. By using such compounds as cathode active materials, a broader plateau region can be achieved.

[0134] The above compound may be at least one selected from the group consisting of LiFePO4, LiFeBO3, Li2Fe(SO4)2, and Li2MnSiO4. By using such a compound as a positive electrode active material, a broader plateau region can be achieved.

[0135] The positive electrode active material layer 106 may contain LiFePO4. By using LiFePO4 as the positive electrode active material, a wider plateau region can be achieved.

[0136] Examples of materials for the positive electrode current collector 105 include metal materials. Examples of metal materials include copper, stainless steel, iron, and aluminum.

[0137] The positive electrode active material layer 106 may contain a solid electrolyte. As the solid electrolyte, the solid electrolyte exemplified as the material constituting the solid electrolyte layer 102 may be used.

[0138] The positive electrode active material may have a median diameter of 0.1 μm or more and 100 μm or less. When the positive electrode active material has a median diameter of 0.1 μm or more, the positive electrode active material and the solid electrolyte can form a good dispersion state. This improves the charge and discharge characteristics of the battery. When the positive electrode active material has a median diameter of 100 μm or less, the lithium diffusion rate improves. This allows the battery to operate at high power.

[0139] The positive electrode active material may have a larger median diameter than the solid electrolyte. This allows the positive electrode active material and the solid electrolyte to form a good dispersion state.

[0140] From the viewpoint of the battery's energy density and output, in the positive electrode active material layer 106, the ratio of the volume of the positive electrode active material to the sum of the volume of the positive electrode active material and the volume of the solid electrolyte may be 0.30 or more and 0.95 or less.

[0141] To prevent the solid electrolyte from reacting with the positive electrode active material, a coating layer may be formed on the surface of the positive electrode active material. This can suppress the rise in the reaction overpotential of the battery. Examples of coating materials included in the coating layer are sulfide solid electrolytes, oxide solid electrolytes, or halide solid electrolytes.

[0142] The thickness of the positive electrode 103 may be 10 μm or more and 500 μm or less. If the thickness of the positive electrode 103 is 10 μm or more, sufficient energy density of the battery can be ensured. If the thickness of the positive electrode 103 is 500 μm or less, the battery can operate at high power.

[0143] The positive electrode 103 may contain a conductive material to enhance its electronic conductivity.

[0144] The positive electrode 103 may contain a binder.

[0145] The same materials that can be used for the negative electrode active material layer 104 may be used as the conductive material and binder.

[0146] The positive electrode 103 may contain a non-aqueous electrolyte, a gel electrolyte, or an ionic liquid in order to facilitate the transfer of lithium ions and improve the output characteristics of the battery.

[0147] Non-aqueous electrolytes include a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent. Examples of non-aqueous solvents are cyclic carbonate solvents, linear carbonate solvents, cyclic ether solvents, linear ether solvents, cyclic ester solvents, linear ester solvents, or fluorine solvents. Examples of cyclic carbonate solvents are ethylene carbonate, propylene carbonate, or butylene carbonate. Examples of linear carbonate solvents are dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate. Examples of cyclic ether solvents are tetrahydrofuran, 1,4-dioxane, or 1,3-dioxolane. Examples of linear ether solvents are 1,2-dimethoxyethane, or 1,2-diethoxyethane. An example of a cyclic ester solvent is γ-butyrolactone. An example of a linear ester solvent is methyl acetate. Examples of fluorinated solvents include fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, or fluorodimethylene carbonate. One non-aqueous solvent selected from these may be used alone, or a mixture of two or more non-aqueous solvents selected from these may be used.

[0148] Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), or LiC(SO2CF3)3. One lithium salt selected from these may be used alone, or a mixture of two or more lithium salts selected from these may be used. The concentration of the lithium salt is, for example, in the range of 0.5 mol / liter to 2 mol / liter.

[0149] As the gel electrolyte, polymer materials impregnated with a non-aqueous electrolyte can be used. Examples of polymer materials include polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, or polymers having ethylene oxide bonds.

[0150] Examples of cations contained in ionic liquids are: (i) aliphatic chain quaternary salts such as tetraalkylammonium or tetraalkylphosphonium, (ii) Aliphatic cyclic ammonium compounds such as pyrrolidiniums, morpholiniums, imidazoliniums, tetrahydropyrimidiniums, piperadiniums, or piperidiniums, (iii) Nitrogen-containing heterocyclic aromatic cations such as pyridiniums or imidazoliums That is the case.

[0151] An example of anion found in ionic liquids is PF6. - BF4 - SbF6 - AsF6 - , SO3CF3 - , N(SO2CF3)2 - , N(SO2C2F5)2 - , N(SO2CF3)(SO2C4F9) - , or C(SO2CF3)3 - That is the case.

[0152] The ionic liquid may contain a lithium salt.

[0153] [Electrolyte layer] The electrolyte layer 102 contains an electrolyte material. The electrolyte layer 102 is composed of, for example, a non-aqueous electrolyte. The electrolyte material contained in the electrolyte layer 102 may be a solid electrolyte or an electrolyte solution. Figure 1 shows an example configuration in which the electrolyte layer 102 is a solid electrolyte.

[0154] When the electrolyte material is a solid electrolyte, a halogen solid electrolyte, a sulfide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, or a complex hydride solid electrolyte may be used as the solid electrolyte.

[0155] A halide solid electrolyte refers to a solid electrolyte containing a halogen element. A halide solid electrolyte may also contain oxygen in addition to the halogen element. A halide solid electrolyte does not contain sulfur (S).

[0156] The halide solid electrolyte may be, for example, a material represented by the following compositional formula (1). Li α M β X γ ...Equation (1) Here, α, β, and γ are values ​​greater than 0, M is at least one selected from the group consisting of metal elements and metalloid elements other than Li, and X is at least one selected from the group consisting of F, Cl, Br, and I.

[0157] "Metallic elements" are B, Si, Ge, As, Sb, and Te.

[0158] "Metallic elements" refer to all elements in groups 1 through 12 of the periodic table, excluding hydrogen, as well as all elements in groups 13 through 16, excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se. In other words, they are the elements that can form cations when forming halogen compounds and inorganic compounds.

[0159] In compositional formula (1), M may contain Y, and X may contain Cl and Br.

[0160] Examples of halide solid electrolytes that may be used include Li3(Ca,Y,Gd)X6, Li2MgX4, Li2FeX4, Li(Al,Ga,In)X4, Li3(Al,Ga,In)X6, LiI, etc. Here, in these solid electrolytes, element X is at least one selected from the group consisting of F, Cl, Br, and I. In this disclosure, when an element in a formula is represented as "(Al,Ga,In)", this notation indicates at least one element selected from the group of elements in parentheses. That is, "(Al,Ga,In)" is synonymous with "at least one selected from the group consisting of Al, Ga, and In". The same applies to other elements.

[0161] Other examples of halide solid electrolytes include Li a Me b Yc It is a compound represented by X6. Here, a + mb + 3c = 6 and c > 0 are satisfied. Me is at least one selected from the group consisting of a metal element other than Li and Y and a metalloid element. m represents the valence of Me. The "metalloid element" is B, Si, Ge, As, Sb, and Te. The "metal element" is all elements contained in Groups 1 to 12 of the periodic table (excluding hydrogen), and all elements contained in Groups 13 to 16 of the periodic table (excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se).

[0162] In order to enhance the ionic conductivity of the halide solid electrolyte material, Me may be at least one selected from the group consisting of Mg, Ca, Sr, Ba, Zn, Sc, Al, Ga, Bi, Zr, Hf, Ti, Sn, Ta, and Nb. The halide solid electrolyte may be Li3YCl6, Li3YBr6, or Li3YBr p Cl 6-p where p satisfies 0 < p < 6.

[0163] The sulfide solid electrolyte means a solid electrolyte containing sulfur (S). The sulfide solid electrolyte may contain not only sulfur but also a halogen element.

[0164] Examples of the sulfide solid electrolyte include, for example, Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, Li2S-GeS2, Li 3.25 Ge 0.25 P 0.75 S4, or Li 10 GeP2S 12 and the like can be used.

[0165] Examples of the oxide solid electrolyte include, for example, NASICON-type solid electrolytes represented by LiTi2(PO4)3 and its element substitution products, perovskite-type solid electrolytes of the (LaLi)TiO3 system, Li 14 ZnGe4O 16, LiSICON-type solid electrolytes such as Li4SiO4, LiGeO4 and their elemental substitutions, Li7La3Zr2O 12 Garnet-type solid electrolytes, such as those represented by elemental substitutions thereof, Li3PO4 and its N-substituted counterparts, and glass or glass ceramics based on Li-BO compounds such as LiBO2 and Li3BO3, with Li2SO4, Li2CO3, etc., added, can be used.

[0166] As a polymer solid electrolyte, for example, a compound of a polymer compound and a lithium salt can be used. The polymer compound may have an ethylene oxide structure. Polymer compounds having an ethylene oxide structure can contain a large amount of lithium salt. Therefore, the ionic conductivity can be further increased. Examples of lithium salts that can be used include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), and LiC(SO2CF3)3. One lithium salt selected from the exemplified lithium salts can be used alone. Alternatively, a mixture of two or more lithium salts selected from the exemplified lithium salts can be used.

[0167] Examples of complex hydride solid electrolytes that can be used include LiBH4-LiI and LiBH4-P2S5.

[0168] The electrolyte layer 102 may contain a halide solid electrolyte. The halide solid electrolyte does not contain sulfur.

[0169] The electrolyte layer 102 may consist substantially of a halide solid electrolyte. In this specification, "substantially" means that the inclusion of impurities at a content of less than 0.1% is permitted. The electrolyte layer 102 may consist substantially of a halide solid electrolyte.

[0170] With the above configuration, the ionic conductivity of the electrolyte layer 102 can be increased. This reduces the decrease in the battery's energy density.

[0171] The electrolyte layer 102 may further contain a binder. The same material that can be used for the negative electrode active material layer 104 may be used as the binder.

[0172] The electrolyte layer 102 may have a thickness of 1 μm or more and 500 μm or less. If the solid electrolyte layer 102 has a thickness of 1 μm or more, the negative electrode 101 and the positive electrode 103 are less likely to short-circuit. If the solid electrolyte layer 102 has a thickness of 500 μm or less, the battery can operate at high power.

[0173] The shape of the solid electrolyte is not particularly limited. If the solid electrolyte is a powder material, its shape may be, for example, needle-shaped, spherical, ellipsoidal, etc. For example, the solid electrolyte may be particulate.

[0174] For example, if the solid electrolyte is particulate (e.g., spherical), the median diameter of the solid electrolyte may be 100 μm or less, or 10 μm or less.

[0175] In this disclosure, “median diameter” means the particle size at which the cumulative volume in the volume-based particle size distribution is equal to 50%. The volume-based particle size distribution is measured, for example, by a laser diffraction analyzer or an image analyzer.

[0176] If the electrolyte layer 102 contains a solid electrolyte, the solid electrolyte can be manufactured, for example, by the following method.

[0177] The raw material powder is prepared to have the desired composition. Examples of raw material powders include oxides, hydroxides, halides, or acid halides.

[0178] For example, if the target composition is Li3YBr4Cl2, LiBr, YCl, and YBr are mixed in a molar ratio of approximately 3:0.66:0.33. The raw material powders may also be mixed in a pre-adjusted molar ratio to compensate for any compositional changes that may occur during the synthesis process.

[0179] The raw material powders are reacted with each other mechanochemically (i.e., using the mechanochemical milling method) in a mixing device such as a planetary ball mill to obtain a reactant. The reactant may be calcined in a vacuum or an inert atmosphere. Alternatively, a mixture of raw material powders may be calcined in a vacuum or an inert atmosphere to obtain the reactant. Calcination is preferably carried out at a temperature of 100°C or higher and 300°C or lower for at least one hour. To suppress compositional changes during calcination, it is preferable that the raw material powders be calcined in a sealed container such as a quartz tube.

[0180] These methods yield solid electrolytes.

[0181] The battery 1000 has a basic configuration of a negative electrode 101, an electrolyte layer 102, and a positive electrode 103, and is sealed in a sealed container to prevent the ingress of air and moisture. The shape of the battery 1000 can be coin-shaped, cylindrical, prismatic, sheet-shaped, button-shaped, flat, or stacked.

[0182] Figure 4 is a schematic cross-sectional view showing a modified example of a battery according to an embodiment of the present disclosure. When the electrolyte material constituting the electrolyte layer 102 is an electrolyte, the battery according to the embodiment of the present disclosure may be a battery 2000 having a configuration such as that shown in Figure 4. In Figure 4, the same reference numerals are used for components having the same function as those shown in Figure 1. The battery 2000 comprises a negative electrode 101, a positive electrode 103, an electrolyte 201, a separator 202, and an outer casing 203. The separator 202 is positioned between the negative electrode 101 and the positive electrode 103. The negative electrode 101 and the positive electrode 103 face each other via the separator 202. The negative electrode 101, the positive electrode 103, the separator 202, and the electrolyte 201 are housed in the outer casing 203. The electrolyte 201 is, for example, an electrolyte impregnated into the negative electrode 101, the positive electrode 103, and the separator 202. In a battery 2000 having a configuration in which an electrolyte solution is used as the electrolyte, the electrolyte solution 201 impregnated in the separator 202 is located between the negative electrode 101 and the positive electrode 103. That is, the electrolyte solution 201 impregnated in the separator 202 thus forms the electrolyte layer. The electrolyte solution 201 may also fill the internal space of the outer casing 203.

[0183] The electrolyte 201 includes, for example, a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.

[0184] Examples of non-aqueous solvents include cyclic carbonate solvents, linear carbonate solvents, cyclic ether solvents, linear ether solvents, cyclic ester solvents, linear ester solvents, or fluorinated solvents. Examples of cyclic carbonate solvents are ethylene carbonate, propylene carbonate, butylene carbonate, or vinylene carbonate. Examples of linear carbonate solvents are dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate. Examples of cyclic ether solvents are tetrahydrofuran, 1,4-dioxane, or 1,3-dioxolane. Examples of linear ether solvents are 1,2-dimethoxyethane, or 1,2-diethoxyethane. An example of a cyclic ester solvent is γ-butyrolactone. An example of a linear ester solvent is methyl acetate. Examples of fluorinated solvents are fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, or fluorodimethylene carbonate. One non-aqueous solvent selected from these may be used alone, or a mixture of two or more non-aqueous solvents selected from these may be used.

[0185] Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), or LiC(SO2CF3)3. One lithium salt selected from these may be used alone, or a mixture of two or more lithium salts selected from these may be used. The concentration of the lithium salt is, for example, in the range of 0.5 mol / liter to 2 mol / liter.

[0186] The separator 202 is lithium ion conductive. The material of the separator 202 is not particularly limited, as long as the passage of lithium ions is permitted. The material of the separator 202 may be at least one selected from the group consisting of solid electrolytes, gel electrolytes, ion exchange resin membranes such as lithium cation exchange resins, semipermeable membranes, and porous membranes. If the separator 202 is made from these materials, the safety of the battery 2000 can be sufficiently ensured. As for solid electrolytes, sulfide solid electrolytes such as Li2S-P2S5 and Li7La3Zr2O 12 Examples of oxide solid electrolytes include (LLZ). Examples of gel electrolytes include gel electrolytes containing fluororesins such as PVdF. Examples of ion exchange resin membranes include cation exchange membranes and anion exchange membranes. Examples of porous membranes include porous membranes made of polyolefin resin and porous membranes made of glass paper obtained by weaving glass fibers into a nonwoven fabric.

[0187] The outer casing 203 is made of a material obtained by laminating a metal foil, such as aluminum foil, with a resin film, such as polyethylene terephthalate (PET) film. The outer casing 203 may also be a resin or metal container.

[0188] The electrolyte material used in the electrolyte layer is not limited to the solid electrolyte or electrolyte solution described above; gel electrolytes or ionic liquids may also be used.

[0189] As the gel electrolyte, polymer materials impregnated with a non-aqueous electrolyte can be used. Examples of polymer materials include polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, or polymers having ethylene oxide bonds.

[0190] Examples of cations contained in ionic liquids are: (i) aliphatic chain quaternary salts such as tetraalkylammonium or tetraalkylphosphonium, (ii) Aliphatic cyclic ammonium compounds such as pyrrolidiniums, morpholiniums, imidazoliniums, tetrahydropyrimidiniums, piperadiniums, or piperidiniums, (iii) A nitrogen-containing heterocyclic aromatic cation such as pyridinium or imidazolium compounds.

[0191] An example of anion found in ionic liquids is PF6. - BF4 - SbF6 - AsF6 - , SO3CF3 - , N(SO2CF3)2 - , N(SO2C2F5)2 - , N(SO2CF3)(SO2C4F9) - , or C(SO2CF3)3 - That is the case.

[0192] The ionic liquid may contain a lithium salt. [Examples]

[0193] The details of this disclosure are disclosed below with reference to examples and reference examples. The following examples are illustrative and this disclosure is not limited to the following examples.

[0194] (Example 1) <Fabrication of the positive electrode> Lithium iron phosphate (LiFePO4, manufactured by Hitachi Zosen Corporation) was used as the positive electrode active material. A positive electrode mixture slurry was obtained by mixing the positive electrode active material with acetylene black (AB) manufactured by Denka Co., Ltd., KF polymer (an N-methyl-2-pyrrolidone (NMP) solution containing polyvinylidene fluoride (PVDF)) manufactured by Kureha Corporation, and an NMP solution. The positive electrode mixture slurry was prepared so that the mass ratio of the positive electrode active material, AB, and PVDF was 90:7:3.

[0195] A 10 μm thick aluminum foil, used as the positive electrode current collector, was coated with a positive electrode mixture slurry on one side. After drying, the positive electrode sheet coated with the positive electrode mixture slurry was pressed. Subsequently, the pressed positive electrode sheet was punched out to 2 cm x 2 cm to produce the positive electrode.

[0196] <Fabrication of the negative electrode> As a pretreatment, nickel foil (10cm x 10cm, thickness: 10μm) was pre-degreased with an organic solvent, then one side was masked and degreased by immersion in an acidic solvent to activate the nickel foil surface. In 1.0 mol / L of methanesulfonic acid, bismuth methanesulfonate was added as a soluble bismuth salt. 3+ A plating bath was prepared by adding ions to a concentration of 0.18 mol / L. The activated nickel foil was connected to a power supply so that current could be applied, and then immersed in the plating bath. Subsequently, the current density was set to 2 A / dm². 2 By controlling the process, Bi was electroplated onto the unmasked nickel foil surface to a thickness of approximately 5 μm. After electroplating, the nickel foil was recovered from the acidic bath, the masking was removed, and it was washed with pure water and dried. Subsequently, the nickel foil electroplated with Bi was heat-treated at 400°C for 60 hours in an electric furnace under an argon atmosphere. After the heat treatment, surface X-ray diffraction measurements were performed on the Bi plating layer on the nickel foil. The X-ray diffraction pattern obtained from this measurement is shown in Figure 2. From this X-ray diffraction pattern, it was confirmed that BiNi with a monoclinic crystal structure belonging to the space group C2 / m was formed. That is, a laminate was obtained consisting of a current collector made of nickel foil and an active material layer made of BiNi with a crystal structure belonging to the space group C2 / m, which was placed in direct contact with the surface of the current collector. Subsequently, the obtained laminate was punched out to 2 cm × 2 cm to create a negative electrode. Furthermore, in the active material layer of the negative electrode in Example 1, the peak intensity ratio I(2) / I(1) in the X-ray diffraction pattern was 0.28 or less.

[0197] <Preparation of test cells> The sides of the positive electrode and the negative electrode were positioned opposite each other. The positive electrode was double-coated with a microporous separator (Cellguard 3401, manufactured by Asahi Kasei). As the electrolyte, a solution was prepared by dissolving LiPF6 in vinylene carbonate (VC) at a concentration of 1.0 mol / L. Using this positive electrode, negative electrode, and electrolyte, a battery was assembled as a test cell for Example 1.

[0198] <Charge / Discharge Test> The test cell of Example 1 was subjected to a current of IT=0.05, calculated from the positive electrode capacitance, in a constant temperature bath at 25°C, resulting in a voltage of 3.2V (vsLi). + Charge to / Li) and then to 2.0V(vsLi + It discharged down to / Li).

[0199] <Result> Figure 5 shows the results of the charge-discharge test of the test cell according to Example 1, and is a graph showing the voltage during discharge and the discharge capacity per unit mass of positive electrode active material. The charge test results showed that the charge capacity of the test cell in Example 1 was 171.9 mAh / g per unit mass of positive electrode active material. The discharge test results, as shown in Figure 5, showed a discharge capacity of 147.3 mAh / g. In other words, the total discharge capacity of the test cell according to Example 1 was 147.3 mAh / g.

[0200] Discharge average of the test cell in Example 1 Voltage The average discharge voltage was 2.58V. Voltage The percentage of the total discharge capacity that falls within the ±0.1V range is the discharge capacity. Voltage This was defined as an index of flatness. Table 2 shows the results for the cell in Example 1. In Table 2, discharge Voltage The above percentage, which is an indicator of flatness, is described as "the ratio of the discharge capacity to the total discharge capacity when the cell voltage is flat." Regarding this percentage, the cell in Example 1 showed a high value of 82%.

[0201] [Table 2]

[0202] (Example 2) <Preparation of solid electrolytes> In an argon atmosphere with a dew point of -60°C or lower (hereinafter referred to as a "dry argon atmosphere"), LiBr, YCl3, and YBr3 were prepared as raw material powders in a molar ratio of LiBr:YCl3:YBr3 = 3:2 / 3:1 / 3. These raw material powders were ground and mixed in a mortar to obtain a mixed powder. Next, the obtained mixture of raw material powders was calcined in an electric furnace in a dry argon atmosphere at 500°C for 3 hours to obtain a calcined product. The obtained calcined product was ground in a mortar using a pestle. In this way, a solid electrolyte having the composition Li3YBr4Cl2 was obtained. Hereinafter, "Li3YBr4Cl2" may be written as "LYBC".

[0203] <Fabrication of the positive electrode> Lithium iron phosphate (LiFePO4) (manufactured by Hitachi Zosen Corporation) was used as the positive electrode active material. The positive electrode was prepared by mixing lithium iron phosphate (LiFePO4) as the positive electrode active material, LYBC as a solid electrolyte, and Showa Denko K.K.'s carbon nanofiber VGCF (registered trademark) as a conductive additive in an argon glove box to obtain a positive electrode mixture powder. The positive electrode active material, solid electrolyte, and conductive additive were mixed in a mass ratio of positive electrode active material:solid electrolyte:conductive additive = 50:40:10.

[0204] <Fabrication of the negative electrode> The negative electrode in Example 2 was fabricated in the same manner as in Example 1. However, the shape of the negative electrode punched out from the laminate composed of the current collector and the active material layer was φ0.92 cm. In this way, a negative electrode with a diameter of φ0.92 cm was fabricated.

[0205] <Preparation of test cells> Within an insulating outer cylinder having an inner diameter of 9.4 mm, a layer formed of positive electrode mixture powder and a negative electrode with a diameter of φ0.92 cm, prepared by the above method, were arranged so that the surface of the negative electrode containing the negative electrode active material faced the layer formed of positive electrode mixture powder. The layer formed of positive electrode mixture powder, the solid electrolyte layer, and the negative electrode were stacked such that a solid electrolyte Li3YBr4Cl2 (80 mg) was placed between the layer formed of positive electrode mixture powder and the layer of the negative electrode containing the negative electrode active material, thereby obtaining a laminate. A pressure of 360 MPa was applied to this laminate in the stacking direction, forming a battery as a test cell equipped with a positive electrode, a solid electrolyte layer, and a negative electrode. In the test cell, the thickness of the positive electrode was 22 μm, the thickness of the solid electrolyte layer was 400 μm, and the thickness of the negative electrode was 16.5 μm.

[0206] Next, current collectors made of stainless steel were attached to the positive and negative electrodes, and current collector leads were attached to the current collectors.

[0207] Finally, an insulating ferrule was used to isolate the inside of the insulating outer cylinder from the outside atmosphere, thereby sealing the inside of the cylinder.

[0208] <Charge / Discharge Test> The fabricated test cells were subjected to charge-discharge tests under the following conditions: They were charged to 3.2V (vsLi+ / Li) in a constant temperature bath at 25°C with a current of IT=0.05 calculated from the positive electrode capacity, and then discharged to 2.0V (vsLi+ / Li).

[0209] <Result> Figure 6 shows the results of the charge-discharge test of the test cell according to Example 2, and is a graph showing the voltage during discharge and the discharge capacity per unit mass of positive electrode active material. The charge test results showed that the charge capacity of the test cell in Example 2 was 171.3 mAh / g per unit mass of positive electrode active material. The discharge test results, as shown in Figure 6, showed a discharge capacity of 148.3 mAh / g. In other words, the total discharge capacity of the test cell according to Example 2 was 148.3 mAh / g.

[0210] Discharge average of test cells in Example 2 VoltageThe voltage was 2.56V. Similar to Example 1, the discharge average was used. Voltage The percentage of the total discharge capacity that falls within the ±0.1V range is the discharge capacity. Voltage This was defined as an index of flatness. Table 3 shows the results for the cell in Example 2. In Table 3, discharge Voltage The above percentage, which is an indicator of flatness, is described as "the ratio of the discharge capacity to the total discharge capacity when the cell voltage is flat." Regarding this percentage, the cell in Example 2 showed a high value of 78%.

[0211] [Table 3]

[0212] (Reference example 1) <Test Cell> ML batteries, which are marketed as coin-type lithium manganese dioxide secondary batteries, are constructed using manganese dioxide as the positive electrode active material, a lithium aluminum alloy as the negative electrode active material, and a solution of the electrolyte dissolved in an organic solvent as the electrolyte. Compared to nickel-cadmium batteries, ML batteries have a higher voltage and a wider plateau region.

[0213] For example, the coin-type lithium manganese dioxide secondary battery "ML2032" (manufactured by Maxell Corporation) has a datasheet that describes the change in battery voltage at a 240kΩ resistor as a discharge characteristic, and it can be considered a battery with a wide plateau region. Therefore, we used the ML2032 as a test cell and conducted a charge-discharge test with a capacity of 65mAh as specified in the ML2032 datasheet.

[0214] <Charge / Discharge Test> The test cell from Reference Example 1 was charged to 3.2V (vsLi+ / Li) at a current value that resulted in IT = 0.05 in an environment of 25°C, and then discharged to 2.0V (vsLi+ / Li).

[0215] <Result> Figure 7 shows the results of the charge-discharge test of the test cell according to Reference Example 1, and is a graph showing the voltage during discharge and the discharge capacity per unit mass of positive electrode active material. As shown in Figure 7, the discharge capacity of the test cell according to Reference Example 1 was 46.1 mAh. That is, the total discharge capacity of the test cell according to Reference Example 1 was 46.1 mAh / g.

[0216] Discharge average of the test cell in Reference Example 1 Voltage The average discharge voltage was 2.33V. Voltage The percentage of the total discharge capacity that falls within the ±0.1V range is the discharge capacity. Voltage This was defined as an index of flatness. Table 4 shows the results for the cell in Reference Example 1. In Table 4, discharge Voltage The above percentage, which is an indicator of flatness, is described as "the ratio of the discharge capacity to the total discharge capacity when the cell voltage is flat." For example, the cell in Reference Example 1 had a percentage of 44%.

[0217] [Table 4]

[0218] (Reference example 2) Similar to Reference Example 1, a coin-type manganese dioxide lithium secondary battery ML2032 (manufactured by Maxell) was used as the test cell for charge-discharge testing.

[0219] <Charge / Discharge Test> The test cell from Reference Example 2 was charged to 3.2V (vsLi+ / Li) at a current of 200μA, i.e., IT = 0.003, in an environment of 25°C, and then discharged to 2.0V (vsLi+ / Li).

[0220] <Result> Figure 8 shows the results of the charge-discharge test of the test cell according to Reference Example 2, and is a graph showing the voltage during discharge and the discharge capacity per unit mass of positive electrode active material. As shown in Figure 8, the discharge capacity of the test cell according to Reference Example 2 was 65.9 mAh. That is, the total discharge capacity of the test cell according to Reference Example 2 was 65.9 mAh / g.

[0221] Average discharge of the test cell in Reference Example 2 Voltage The average discharge voltage was 2.49V. Voltage The percentage of the total discharge capacity that falls within the ±0.1V range is the discharge capacity. Voltage This was defined as an index of flatness. Table 5 shows the results for the cells in Reference Example 2. In Table 5, discharge Voltage The above percentage, which is an indicator of flatness, is described as "the ratio of the discharge capacity to the total discharge capacity when the cell voltage is flat." For example, the cell in Reference Example 2 had a percentage of 57%.

[0222] [Table 5]

[0223] (Reference example 3) <Fabrication of the positive electrode> The positive electrode active material was prepared by coprecipitation. [Ni 0.60 Co 0.20 Mn 0.20 A hydroxide represented by ](OH)2 was calcined at 500°C to obtain a nickel-cobalt-manganese composite oxide. The obtained composite oxide and lithium hydroxide LiOH were dry-mixed in a molar ratio of Li / (Ni+Co+Mn)=1.1, and the mixture was heated to 1000°C under an oxygen atmosphere and calcined for 10 hours. The elemental ratios in the composition of the calcined mixture were derived using an inductively coupled plasma atomic emission spectrometer CIROS120 (SPECTRO). The derived elemental ratios, in molar ratio, were Li:Ni:Co:Mn=1.04:0.59:0.20:0.19.

[0224] A cathode mixture slurry was obtained by mixing the cathode active material prepared in this manner with acetylene black (AB) manufactured by Denka Co., Ltd., KF polymer (an N-methyl-2-pyrrolidone (NMP) solution containing polyvinylidene fluoride (PVDF)) manufactured by Kureha Corporation, and an NMP solution. The cathode mixture slurry was prepared so that the cathode active material, AB, and PVDF were in a mass ratio of 90:7:3.

[0225] A positive electrode mixture slurry was applied to one side of an aluminum foil with a thickness of 10 μm as a positive electrode current collector. The positive electrode sheet with the positive electrode mixture slurry applied to the positive electrode current collector was pressed after drying. Thereafter, the pressed positive electrode sheet was punched into a size of 2 cm × 2 cm to fabricate a positive electrode.

[0226] <Fabrication of negative electrode> The negative electrode of Reference Example 3 was fabricated in the same manner as in Example 1.

[0227] <Fabrication of test cell> The battery as the test cell of Reference Example 3 was assembled in the same manner as in Example 1 using the positive electrode and negative electrode of Reference Example 3.

[0228] <Charge-discharge test> The test cell of Reference Example 3 was charged at a current of IT = 0.05 calculated from the positive electrode capacity in a constant temperature bath at 25°C up to 3.9 V (vsLi + / Li), and then discharged to 1.5 V (vsLi + / Li).

[0229] <Results> FIG. 9 shows the results of the charge-discharge test of the test cell according to Reference Example 3, and is a graph showing the voltage during discharge and the discharge capacity per unit mass of the positive electrode active material. As a result of the charge-discharge test, as shown in FIG. 9, the discharge capacity of the test cell of Reference Example 3 was 196.1 mAh / g per unit mass of the positive electrode active material. That is, the total discharge capacity of the test cell according to Reference Example 3 was 196.1 mAh / g.

[0230] The average discharge Voltage of the test cell of Reference Example 3 was 2.97 V. The ratio of the capacity included in the range of ±0.1 V with respect to the average discharge Voltage to the total discharge capacity was defined as an index of discharge Voltage flatness. Table 6 shows the results of the cell of Reference Example 3. In Table 6, the discharge VoltageThe above percentage, which is an indicator of flatness, is described as "the ratio of the discharge capacity to the total discharge capacity when the cell voltage is flat." For example, the cell in Reference Example 3 had a ratio of 38%.

[0231] [Table 6]

[0232] Based on the above, by including lithium iron phosphate (LiFePO4) as the positive electrode active material and an alloy containing Bi and Ni as the negative electrode active material, the plateau region of the battery can be expanded.

[0233] Furthermore, it was confirmed that batteries with a wide plateau range can be realized, similar to Examples 1 and 2, even if the positive electrode active material is not limited to lithium iron phosphate (LiFePO4), and the positive electrode active material includes a compound having a transition metal element and an oxoanion and capable of intercalating and releasing lithium ions (particularly a compound that involves a two-phase coexistence reaction in its electrochemical reaction with lithium), and the negative electrode active material includes an alloy containing Bi and Ni. [Industrial applicability]

[0234] The battery described herein can be used, for example, as a lithium secondary battery.

Claims

1. Positive electrode and, The negative electrode and, An electrolyte layer located between the positive electrode and the negative electrode, Equipped with, The positive electrode has a positive electrode active material layer, The positive electrode active material layer contains a compound having a transition metal element and an oxoanion, and capable of intercalating and releasing lithium ions. The negative electrode comprises a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer contains BiNi, The BiNi mentioned above has a monoclinic crystal structure whose space group belongs to C2 / m. battery.

2. The oxoanion comprises B, Si, P, or S. The battery according to claim 1.

3. The oxoanion is BO 3 3- , SiO 4 4- , PO 4 3- , P 2 O 7 4- , or SO 4 2- and is The battery according to claim 2.

4. The electrochemical reaction between the aforementioned compound and lithium includes a two-phase coexistence reaction. The battery according to claim 1.

5. The aforementioned compound has an olivine structure, The battery according to claim 1.

6. The transition metal element is at least one selected from the group consisting of Fe, Mn, Co, and Ni. The battery according to claim 1.

7. The positive electrode active material layer is LiFePO 4 including, The battery according to claim 1.

8. The negative electrode active material layer comprises LiBi and Li 3 Includes at least one selected from the group consisting of Bi, The battery according to claim 1.

9. The negative electrode active material layer does not contain a solid electrolyte. The battery according to claim 1.

10. In the X-ray diffraction pattern of the negative electrode active material layer obtained by surface X-ray diffraction measurement using Cu-Kα rays, Let I(1) be the height intensity of the maximum peak that exists in the diffraction angle range 2θ from 29° to 31°. When I(2) is the height intensity of the maximum peak that exists in the diffraction angle range 2θ of 41° to 43°, The ratio of I(2) to I(1), I(2) / I(1), is 0.28 or less. The battery according to claim 1.

11. The battery according to claim 1, wherein the negative electrode current collector includes at least one selected from the group consisting of Cu and Ni.

12. The negative electrode active material layer is a heat-treated plating layer. The battery according to claim 1.

13. The electrolyte layer is a solid electrolyte layer. The battery according to claim 1.

14. The solid electrolyte layer comprises a halogenated solid electrolyte. The halogenated solid electrolyte is sulfur-free. The battery according to claim 13.

15. The solid electrolyte layer contains a sulfide solid electrolyte. The battery according to claim 13.

16. The electrolyte layer contains an electrolyte solution. The battery according to claim 1.

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