Battery Control System

Abstract

The present invention provides a battery control system that makes it possible for two or more types of batteries to be used in appropriate situations according to temperature. According to the present invention, a battery control system has a first battery that is for normal-temperature use, a second battery that is for low-temperature use, a first circuit that has a first transistor and is electrically connected to the first battery, a second circuit that has a second transistor and is electrically connected to the second battery, and at least one temperature sensor that detects the temperature of the first battery and the second battery. When the temperature detected using the temperature sensor is at or above Tr, the power of the second battery is transferred to the first battery via the first circuit and the second circuit, and when the temperature detected using the temperature sensor is below Tr, the power of the first battery is transferred to the second battery via the first circuit and the second circuit.

Description

Battery control system and vehicle

[0001] One aspect of the present invention relates to a battery control system or a vehicle equipped with a battery control system.

[0002] Another embodiment of the present invention is not limited to the above technical field, but relates to an electronic device equipped with a battery control system.Another embodiment of the present invention relates to a power storage device equipped with a battery control system, and the power storage device can store power obtained from a power generation facility such as a solar power generation panel.

[0003] One embodiment of the present invention is not limited to the above technical fields, but relates to a semiconductor device, a display device, a light-emitting device, a recording device, a driving method thereof, or a manufacturing method thereof. That is, the technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method.

[0004] Secondary batteries have become indispensable in modern society as a reusable energy source. Secondary batteries that use lithium ions as carrier ions are called lithium-ion batteries, while secondary batteries that use sodium ions as carrier ions are called sodium-ion batteries.

[0005] A configuration has been proposed for a vehicle equipped with a secondary battery, which includes a first battery that stores power supplied to a drive source, and a second battery that has characteristics that provide greater output at low temperatures than the first battery (see Patent Document 1).

[0006] JP 2020-92509 A

[0007] The above-mentioned Patent Document 1 describes that when the temperature is below a predetermined level, the second battery is used preferentially over the first battery. It also describes that the usage ratio of the first battery and the second battery may be controlled to change depending on the temperature, but does not disclose any specific control method. In such a control system, it is important that the two types of batteries are used in an appropriate state depending on the temperature.

[0008] In view of the above, one embodiment of the present invention aims to provide a battery control system including two or more types of batteries, in which each battery is used in an appropriate state depending on temperature. Another embodiment of the present invention aims to provide a battery control system including two or more types of batteries, in which an output from each battery is controlled depending on temperature. Another embodiment of the present invention aims to provide a battery control system including two or more types of batteries, in which an energy exchange, i.e., a power transfer, is enabled between the batteries depending on temperature.

[0009] Another object of one embodiment of the present invention is to enable efficient use of batteries and to suppress unevenness in the state of deterioration.Another object of one embodiment of the present invention is to supply stable power.

[0010] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that it is possible to extract problems other than these from the description in the specification, drawings, and claims (hereinafter referred to as the specification, etc.).

[0011] In view of the above, one aspect of the present invention is a battery chargeable / dischargeable device including a first battery capable of being charged / discharged in a first temperature range, a second battery capable of being charged / discharged in a second temperature range, a first circuit having a first transformer electrically connected to the first battery, a second circuit having a second transformer electrically connected to the second battery, and one or more temperature sensors for detecting temperatures of the first battery and the second battery, wherein when a temperature detected by the temperature sensor is equal to or higher than Tr, the first circuit and the second circuit detect a temperature of the second battery. a first circuit and a second circuit for transferring power from the first battery to the second battery when a temperature detected by a temperature sensor is lower than Tr; an upper limit of the first temperature range is higher than an upper limit of a second temperature range, a lower limit of the first temperature range is lower than an upper limit of the second temperature range, and a lower limit of the second temperature range is lower than a lower limit of the first temperature range; and Tr satisfies a range higher than the lower limit of the first temperature range and lower than the upper limit of the second temperature range.

[0012] Another aspect of the present invention is a battery control system having a first battery that can be charged and discharged within a first temperature range, a second battery that can be charged and discharged within a second temperature range, a first DCDC circuit electrically connected to the first battery, a second DCDC circuit electrically connected to the second battery, and one or more temperature sensors that detect the temperatures of the first battery and the second battery, wherein when the temperature detected using the temperature sensor is equal to or higher than Tr, the first DCDC circuit makes the output from the first battery greater than the output from the second battery, and when the temperature detected using the temperature sensor is lower than Tr, the second DCDC circuit makes the output from the second battery greater than the output from the first battery, wherein the upper limit of the first temperature range is higher than the upper limit of the second temperature range, the lower limit of the first temperature range is lower than the upper limit of the second temperature range, and Tr satisfies a range higher than the lower limit of the first temperature range and lower than the upper limit of the second temperature range.

[0013] Another aspect of the present invention is a battery comprising: a first battery capable of being charged and discharged within a first temperature range; a second battery capable of being charged and discharged within a second temperature range; a first circuit having a first transformer electrically connected to the input side of the first battery; a second circuit having a second transformer electrically connected to the input side of the second battery; a first DCDC circuit electrically connected to the output side of the first battery; a second DCDC circuit electrically connected to the output side of the second battery; and one or more temperature sensors that detect the temperatures of the first battery and the second battery, wherein when the temperature detected by the temperature sensor is equal to or higher than Tr, the first DCDC circuit makes the output from the first battery larger than the output from the second battery, and the temperature sensor is used to detect the temperature of the first battery. When the detected temperature is below Tr, the second DCDC circuit increases the output from the second battery to be greater than the output from the first battery; when the temperature detected using the temperature sensor is equal to or greater than Tr, the first circuit and the second circuit transfer power from the second battery to the first battery; when the temperature detected using the temperature sensor is below Tr, the first circuit and the second circuit transfer power from the first battery to the second battery; the upper limit of the first temperature range is higher than the upper limit of the second temperature range, the lower limit of the first temperature range is lower than the upper limit of the second temperature range, and Tr satisfies a range higher than the lower limit of the first temperature range and lower than the upper limit of the second temperature range.

[0014] In one aspect of the present invention, it is preferable that the discharge capacity of the second battery when discharged at the lower limit of the second temperature range is 50% or more of the discharge capacity when discharged at 25°C.

[0015] In one aspect of the present invention, the first battery is preferably a lithium ion battery, and the second battery is preferably a sodium ion battery.

[0016] In one embodiment of the present invention, it is preferable that the positive electrode active material of the first battery has a layered rock salt crystal structure, and the positive electrode active material of the second battery has an olivine crystal structure.

[0017] In one aspect of the present invention, the positive electrode active material of the first battery preferably contains Li, Ni, Co, and Mn, and the positive electrode active material of the second battery preferably contains Li, Fe, and phosphorus.

[0018] In one aspect of the present invention, the median diameter of the positive electrode active material of the second battery is preferably smaller than the median diameter of the positive electrode active material of the first battery.

[0019] In one aspect of the present invention, the electrolyte of the second battery is different from the electrolyte of the first battery, and the electrolyte of the second battery contains ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC), and when the total content of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate is 100 vol%, it is preferable that the volume ratio of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate is x:y:100-x-y (where 5≦x≦35 and 0<y<65).

[0020] One aspect of the present invention is a vehicle equipped with the above-described battery control system.

[0021] The battery control system according to one aspect of the present invention makes it possible to use each battery in an appropriate state according to temperature. The battery control system according to one aspect of the present invention also makes it possible to control the output from each battery according to temperature. The battery control system according to one aspect of the present invention also makes it possible to exchange energy, i.e., transfer power, between each battery according to temperature.

[0022] According to the above-described embodiment of the present invention, it is possible to efficiently use each battery and suppress unevenness in the state of deterioration of the batteries. Furthermore, according to the above-described embodiment of the present invention, it is possible to supply stable power.

[0023] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc.

[0024] FIGS. 1A and 1B are diagrams illustrating a battery control system according to one aspect of the present invention. FIG. 2 is a diagram illustrating a battery control system according to one aspect of the present invention. FIGS. 3A and 3B are diagrams illustrating a battery control system according to one aspect of the present invention. FIGS. 4A and 4B are diagrams illustrating a battery control system according to one aspect of the present invention. FIG. 5 is a diagram illustrating a battery control system according to one aspect of the present invention. FIG. 6 is a diagram illustrating a battery control system according to one aspect of the present invention. FIGS. 7A to 7E are diagrams illustrating a battery control system according to one aspect of the present invention. FIGS. 8A and 8B are diagrams illustrating a battery control system according to one aspect of the present invention. FIGS. 9A and 9B are diagrams illustrating a battery control system according to one aspect of the present invention. FIG. 10 is a diagram illustrating a battery control system according to one aspect of the present invention. FIGS. 11A and 11B are diagrams illustrating an electric vehicle equipped with a battery control system according to one aspect of the present invention. FIG. 12 is a diagram illustrating an example of using a battery control system in an electric vehicle according to one aspect of the present invention. FIG. 13 is a diagram illustrating an example of using a battery control system in an electric vehicle according to one aspect of the present invention. FIG. 14 is a diagram illustrating an example of using a battery control system in an electric vehicle according to one aspect of the present invention. FIGS. 15A and 15B are diagrams illustrating a positive electrode according to one embodiment of the present invention. FIG. 16 is a diagram illustrating a method for producing a positive electrode active material according to one embodiment of the present invention. FIG. 17 is a diagram illustrating a method for producing a positive electrode active material according to one embodiment of the present invention. FIG. 18 is a diagram illustrating a method for producing a positive electrode active material according to one embodiment of the present invention. FIGS. 19A and 19B are diagrams illustrating a battery according to one embodiment of the present invention. FIGS. 20A and 20B are diagrams illustrating a laminate cell according to one embodiment of the present invention. FIGS. 21A and 21B are diagrams illustrating a method for producing a laminate cell according to one embodiment of the present invention. FIGS. 22A to 22C are diagrams illustrating a battery cell according to one embodiment of the present invention. FIGS. 23A to 23C are diagrams illustrating a battery cell according to one embodiment of the present invention. FIGS. 24A to 24D are diagrams illustrating a cylindrical battery cell according to one embodiment of the present invention. FIGS. 25A to 25C are diagrams illustrating a vehicle according to one embodiment of the present invention.

[0025] Hereinafter, examples of embodiments of the present invention will be described with reference to the drawings, etc. However, the present invention should not be construed as being limited to the following examples. The embodiments of the present invention can be modified within the scope of the spirit of the present invention.

[0026] Embodiment 1 In this embodiment, a battery control system according to one embodiment of the present invention will be described.

[0027] As shown in FIG. 1A , a battery control system 10 according to one embodiment of the present invention includes at least a driving battery 101 , a temperature sensor 102 , and a battery management unit (referred to as BMU) 112 .

[0028] The battery control system 10 in FIG. 1B also includes at least a driving battery 101, a temperature sensor 102, a BMU 112, and a DCDC circuit 105.

[0029] <Configuration Example 1 of Battery Control System> In a battery control system 10 according to one embodiment of the present invention, the driving battery 101 includes two types of batteries: a battery 101a and a battery 101b. For example, the battery 101a can be a room-temperature battery with excellent battery characteristics at room temperature or medium temperature, and the battery 101b can be a low-temperature battery with excellent battery characteristics at low temperatures. The room-temperature battery, which will be described in detail later, can be charged and discharged in a first temperature range. The low-temperature battery, which will be described in detail later, can be charged and discharged in a second temperature range. The battery control system 10 according to one embodiment of the present invention can control these two types of batteries as follows.

[0030] The battery control system 10 of one embodiment of the present invention controls the transfer of power from the battery 101b to the battery 101a when it determines using the temperature sensor 102 that the temperature of the driving battery 101 or the like is equal to or higher than Tr. Furthermore, the battery control system 10 of one embodiment of the present invention controls the transfer of power from the battery 101a to the battery 101b when it determines using the temperature sensor 102 that the temperature of the driving battery 101 or the like is lower than Tr. Details of the temperature sensor will be described later.

[0031] The temperature Tr can be determined based on the temperature ranges in which the normal temperature battery and the low temperature battery can be charged and discharged. Specifically, Tr should be higher than the lower limit of the first temperature range in which the normal temperature battery can be charged and discharged, and lower than the upper limit of the second temperature range in which the low temperature battery can be charged and discharged.

[0032] Furthermore, for room-temperature batteries, the output decreases as the temperature drops, so the temperature range of Tr can be determined based on the percentage of output reduction. For example, it is desirable to satisfy a range lower than the temperature at which the output of the room-temperature battery drops to 80% of its maximum output and higher than the lower limit of the temperature range in which charging and discharging is possible. However, the percentage of reduction in the maximum output indicated by the above numerical values ​​can be determined arbitrarily, and it is desirable for this percentage to be either 70% or more and 95% or less.

[0033] Specifically, the temperature Tr may be any one temperature selected from the range of -40°C to 85°C, preferably from -20°C to 45°C.

[0034] The battery control system 10 according to one aspect of the present invention enables the above-described control using a circuit including a transformer, etc. The circuit including a transformer, etc. may be provided in the BMU 112.

[0035] According to this aspect of the present invention, power can be exchanged between the batteries, i.e., power can be transferred, depending on the temperature. As a result, each battery can be used in an appropriate state depending on the temperature. Furthermore, uneven deterioration of the batteries can be suppressed, and more stable power can be supplied.

[0036] <Configuration Example 2 of Battery Control System> The battery control system 10 according to one aspect of the present invention can also control the above-described two types of batteries as follows.

[0037] When the battery control system 10 of one embodiment of the present invention determines using the temperature sensor 102 that the temperature of the driving battery 101 or the like is Tr, it can control the output from the battery 101a to be higher than the output from the battery 101b. Note that in this specification and the like, the output from the battery may be interpreted as the power of the battery. Furthermore, when the battery control system 10 of one embodiment of the present invention determines using the temperature sensor 102 that the temperature of the driving battery 101 or the like is lower than Tr, it can control the output from the battery 101b to be higher than the output from the battery 101a.

[0038] The temperature Tr is the temperature as described in <Configuration Example 1 of Battery Control System>.

[0039] In the battery control system 10 of one embodiment of the present invention, the above-described control is possible using the DCDC circuit 105. Typically, the above-described control is possible using a switch (SW) included in the DCDC circuit 105.

[0040] Furthermore, the DCDC circuit 105 may have a function of aligning the output voltages of the batteries 101a and 101b if there is a difference between the output voltages.

[0041] According to one aspect of the present invention, it is possible to control the output from each battery according to the temperature. As a result, each battery can be used in an appropriate state according to the temperature. Furthermore, it is possible to suppress unevenness in the deterioration state of each battery, and more stable power can be supplied.

[0042] <Configuration Example 3 of Battery Control System> The battery control system 10 according to an aspect of the present invention can also control the above-described two types of batteries as follows.

[0043] For example, after controlling the output from each battery to be different depending on the temperature Tr as in <Configuration Example 2 of Battery Control System>, it is possible to control the transfer of power between each battery depending on the temperature Tr as in <Configuration Example 1 of Battery Control System>.

[0044] Furthermore, for example, after transferring power between each battery according to temperature Tr as in <Configuration Example 1 of Battery Control System>, it is also possible to control the output from each battery to be different according to temperature Tr as in <Configuration Example 2 of Battery Control System>.

[0045] The temperature Tr is the temperature as described in <Configuration Example 1 of Battery Control System>.

[0046] According to one embodiment of the present invention, each battery can be used in an appropriate state depending on the temperature, and the unevenness in the deterioration state of each battery can be suppressed, thereby enabling a more stable power supply.

[0047] Next, each of the components shown in FIGS. 1A and 1B will be described.

[0048] 1A and 1B, a battery control system 10 according to one embodiment of the present invention includes a driving battery 101. In this embodiment, at least two types of batteries, 101a and 101b, are used as the driving battery 101. The batteries 101a and 101b may be distinguished from each other by assigning ordinal numbers such as first and second.

[0049] Note that the battery control system 10 according to one embodiment of the present invention may include two or more types of batteries, for example, three types of batteries. That is, the two types of batteries described in the above <Configuration Examples 1 and 2 of the Battery Control System> may be replaced by two or more types of batteries, for example, three types of batteries. As the number of types of batteries increases, the number of temperatures corresponding to the temperature Tr exemplified in the above Configuration Examples 1 to 3 can be increased.

[0050] For example, when three types of batteries, namely, batteries 101a to 101c, are used, the above-mentioned <Configuration Example 1 of Battery Control System> can perform the following control.

[0051] A battery control system 10 according to one embodiment of the present invention controls the transfer of power from one or both of batteries 101b and 101c to battery 101a when it determines, using a temperature sensor 102, that the temperature of the driving battery 101 or the like is equal to or higher than Tr1. Furthermore, the battery control system 10 according to one embodiment of the present invention controls the transfer of power from one or both of batteries 101a and 101c to battery 101b when it determines, using the temperature sensor 102, that the temperature of the driving battery 101 or the like is lower than Tr1 and equal to or higher than Tr2. Furthermore, the battery control system 10 according to one embodiment of the present invention can control the transfer of power from one or both of batteries 101a and 101b to battery 101c when it determines, using the temperature sensor 102, that the temperature of the driving battery 101 or the like is lower than Tr2.

[0052] The temperatures Tr1 and Tr2 are determined based on the temperature range in which the room temperature battery can be charged and discharged, with the temperature Tr1 being lower than the temperature Tr2. Specifically, the temperatures Tr1 and Tr2 are each preferably any one of the temperatures selected from the range of -40°C or higher and 85°C or lower, and preferably -20°C or higher and 45°C or lower.

[0053] The temperatures Tr1 and Tr2 are determined based on the temperature range in which the room temperature battery can be charged and discharged, and can be set to, for example, the temperatures at which the output of the room temperature battery is 60% and 80% of the maximum output. However, 60% and 80% are specifications of the battery control system 10, and the percentage of maximum output can be determined arbitrarily.

[0054] For example, when three types of batteries, namely, batteries 101a to 101c, are used, the above-mentioned <Configuration Example 2 of Battery Control System> can perform the following control.

[0055] The battery control system 10 according to one embodiment of the present invention can control the output from the battery 101a to be higher than the outputs from the batteries 101b and 101c when it determines, using the temperature sensor 102, that the temperature of the driving battery 101 or the like is equal to or higher than Tr1. Furthermore, the battery control system 10 according to one embodiment of the present invention can control the output from the battery 101b to be higher than the outputs from the batteries 101a and 101c when it determines, using the temperature sensor 102, that the temperature of the driving battery 101 or the like is lower than Tr1 and equal to or higher than Tr2. Furthermore, the battery control system 10 according to one embodiment of the present invention can control the output from the battery 101c to be higher than the outputs from the batteries 101a and 101b when it determines, using the temperature sensor 102, that the temperature of the driving battery 101 or the like is lower than Tr2.

[0056] The temperatures Tr1 and Tr2 are determined based on the temperature range in which the room temperature battery can be charged and discharged, with the temperature Tr1 being lower than the temperature Tr2. Specifically, the temperatures Tr1 and Tr2 are each preferably any one of the temperatures selected from the range of -40°C or higher and 85°C or lower, and preferably -20°C or higher and 45°C or lower.

[0057] The temperatures Tr1 and Tr2 are determined based on the temperature range in which the room temperature battery can be charged and discharged, and can be set to, for example, the temperatures at which the output of the room temperature battery is 60% and 80% of the maximum output. However, 60% and 80% are specifications of the battery control system 10, and the percentage of maximum output can be determined arbitrarily.

[0058] For example, when three types of batteries, namely, batteries 101a to 101c, are used, temperatures Tr1 and Tr2 can be applied to the above-mentioned <Configuration Example 3 of Battery Control System> in the same manner as above.

[0059] In this way, the driving battery 101 may include two or more types of batteries.

[0060] The battery 101a and the battery 101b included in the driving battery 101 preferably include an assembled battery. An assembled battery includes a plurality of battery cells. The battery 101a and the battery 101b may also include a single battery cell (simply referred to as a battery cell). When assembled batteries are used for the battery 101a and the battery 101b, the battery control system 10 of one embodiment of the present invention is preferably applied to an electric vehicle (EV), a power storage device, or the like. The EV will be described later. When battery cells are used for the battery 101a and the battery 101b, the battery control system 10 of one embodiment of the present invention is preferably applied to an electronic device such as a smartphone.

[0061] <Room Temperature Battery> Of the two types of batteries exemplified as the battery control system 10 according to one aspect of the present invention, one is a room temperature battery and the other is a low temperature battery.

[0062] For example, the battery 101a used as a room-temperature battery is one that can be charged and discharged at room temperature or a medium temperature. That is, the battery 101a can be charged and discharged within a first temperature range, and the first temperature range is preferably 0°C or higher and +85°C or lower, more preferably +5°C or higher and +65°C or lower, even more preferably +5°C or higher and +45°C or lower, and even more preferably +5°C or higher and +35°C or lower.

[0063] Being chargeable and dischargeable means that cycle characteristics can be obtained at the above temperature, and it is preferable that the battery 101a has good cycle characteristics at the above temperature. The cycle characteristics are obtained by repeating a cycle (referred to as a cycle test) under specified conditions, with charge and discharge being one cycle, for example, 200 times. The cycle characteristics are sometimes expressed as a discharge capacity or a discharge capacity retention rate relative to the number of cycles. The discharge capacity retention rate is sometimes evaluated as the degree to which the discharge capacity at the final cycle, for example, the 200th cycle, is maintained relative to the maximum discharge capacity. A retention rate of 80% or more, preferably 90% or more, more preferably 95%, and even more preferably 98% or more, indicates good cycle characteristics. The battery for which the cycle test is performed may be either a half-cell or a full-cell. In this embodiment, the cycle test is preferably performed on a full-cell.

[0064] At temperatures below the lower limit of the first temperature range, the room temperature battery cannot be charged or discharged, or even if it can be charged or discharged, it cannot obtain a sufficient discharge capacity. The inability to obtain a sufficient discharge capacity includes, for example, a case where the discharge capacity retention rate in the cycle characteristics is less than 50%.

[0065] At temperatures higher than the upper limit of the first temperature range, the room temperature battery cannot be charged or discharged, or even if it can be charged or discharged, it cannot obtain a sufficient discharge capacity. The inability to obtain a sufficient discharge capacity includes, for example, a case where the discharge capacity retention rate in the cycle characteristics is less than 50%.

[0066] <Low Temperature Battery> A low temperature battery has different battery characteristics from a normal temperature battery. For example, the battery 101b used as a low temperature battery is one that can be charged and discharged at low temperatures. That is, the battery 101b can be charged and discharged in a second temperature range, which is preferably lower than 0°C and higher than -40°C, more preferably lower than -5°C and higher than -30°C, and even more preferably lower than -10°C and higher than -20°C.

[0067] The relationship between the above-mentioned first temperature range and the above-mentioned second temperature range is preferably such that the upper limit of the first temperature range is higher than the upper limit of the second temperature range, the lower limit of the first temperature range is lower than the upper limit of the second temperature range, and the lower limit of the second temperature range is lower than the lower limit of the first temperature range.

[0068] The term "chargeable / dischargeable" means that the cycle characteristics can be obtained at the above temperature. The battery for the cycle test may be either a half cell or a full cell, but in this embodiment, the cycle test is preferably performed on a full cell.

[0069] Furthermore, as for the discharge characteristics of a battery capable of being charged and discharged at low temperatures, the discharge capacity in an environment of 0° C. or below, preferably −20° C. or below, more preferably −40° C. or below, i.e., the value of the discharge capacity at the lower limit of the second temperature range, is preferably 50% or more, more preferably 60% or more, more preferably 70% or more, more preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more of the value of the discharge capacity in an environment of 25° C. Furthermore, the form of the battery to be subjected to the discharge test may be either a half cell or a full cell, but in this embodiment, the discharge test is preferably performed on a full cell.

[0070] At temperatures below the lower limit of the second temperature range, the low-temperature battery cannot be charged or discharged, or even if it can be charged or discharged, it cannot obtain a sufficient discharge capacity. The inability to obtain a sufficient discharge capacity includes, for example, a case where the discharge capacity retention rate in the cycle characteristics is less than 50%.

[0071] At temperatures higher than the upper limit of the second temperature range, the low-temperature battery cannot be charged or discharged, or even if it can be charged or discharged, it cannot obtain a sufficient discharge capacity. The inability to obtain a sufficient discharge capacity includes, for example, a case where the discharge capacity retention rate in the cycle characteristics is less than 50%.

[0072] In this way, it is preferable that battery 101a has different battery characteristics from battery 101b. In other words, the temperature range in which battery 101a can be charged and discharged is different from the temperature range in which battery 101b can be charged and discharged. Having two or more types of batteries with different temperature ranges in which they can be charged and discharged is preferable because it allows driving battery 101 to be charged and discharged over a wide temperature range.

[0073] A lithium ion battery can be used as the room temperature battery that satisfies the above battery characteristics, and a sodium ion battery can be used as the low temperature battery that satisfies the same battery characteristics. In other words, the room temperature battery can be a battery with a different carrier ion from the low temperature battery.

[0074] Alternatively, a combination of lithium ion batteries may be used as a battery that satisfies the above-described battery characteristics. In this case, a lithium composite oxide (sometimes referred to as NCM) containing Ni, Mn, and Co is used as the positive electrode active material for the room temperature battery, and LiFePO 4 having an olivine-type crystal structure is used as the positive electrode active material for the low temperature battery. ４ (sometimes referred to as LFP) can be used. Alternatively, LFP can be used as the positive electrode active material for the room temperature battery, and NCM can be used as the positive electrode active material for the low temperature battery. NCM and LFP will be described later. In other words, the positive electrode active material for the room temperature battery may be a lithium ion battery different from the positive electrode active material for the low temperature battery.

[0075] Furthermore, when using a combination of lithium-ion batteries, the same type of positive electrode active material may be used. In this case, it is preferable to make the particle size of the positive electrode active material for the room temperature battery different from that of the positive electrode active material for the low temperature battery. For example, it is preferable to make the particle size of the positive electrode active material for the low temperature battery smaller than that of the positive electrode active material for the room temperature battery. Here, the particle size can be, for example, the median diameter (D50).

[0076] Furthermore, when using a combination of lithium-ion batteries, if the same type of positive electrode active material is used, the organic solvents may be different. In this case, it is preferable to use an organic solvent suitable for a room-temperature battery (sometimes referred to as a room-temperature organic solvent) and an organic solvent suitable for a low-temperature battery (sometimes referred to as a low-temperature organic solvent). In other words, the organic solvent for the room-temperature battery may be different from that for the low-temperature battery.

[0077] As described above, in one embodiment of the present invention, two or more types of batteries with different battery characteristics depending on temperature are used, so that the driving battery 101 can operate in a wide temperature environment.

[0078] Furthermore, in one embodiment of the present invention, heat generated from one of two or more types of batteries may be used as a heat source to warm the other. For example, when a low-temperature battery is charged or discharged in a low-temperature environment, the low-temperature battery generates heat. This heat can be used to warm the room-temperature battery in the low-temperature environment. Then, after the room-temperature battery has warmed up, for example, after its temperature reaches 0°C or higher, the room-temperature battery can be operated. Battery operation includes at least charging and discharging.

[0079] 1A and 1B, the battery control system 10 according to one aspect of the present invention includes a temperature sensor 102. The temperature sensor 102 is preferably provided at a position where it can detect the temperature of the driving battery 101.

[0080] The battery control system 10 according to one embodiment of the present invention may be capable of detecting the temperatures of the battery 101a and the battery 101b, and may be provided with at least two or more temperature sensors 102. When two or more temperature sensors 102 are provided, it is also possible to detect an average temperature.

[0081] For example, when the battery 101a and the battery 101b are housed in the same housing as a battery pack, the temperature of the battery 101a and the temperature of the battery 101b can be detected by locating one or more temperature sensors 102 in contact with the housing. In the case of a housing housed under the floor of a vehicle, when two or more temperature sensors are provided for the housing, it is preferable to locate them on the low-temperature side close to the outside air and on the high-temperature side close to the interior of the vehicle. In this way, locating two or more temperature sensors on the low-temperature side and the high-temperature side makes it easier to manage the temperature of the battery, which is preferable.

[0082] Furthermore, if the housing has no or little temperature distribution, it is sufficient to provide one temperature sensor 102 .

[0083] When a thermistor is used as the temperature sensor 102, the contact portion of the thermistor is brought into contact with the driving battery 101 to detect a change in the resistance value of the contact portion, and the temperature of the driving battery 101 can be calculated based on the resistance value. The driving battery 101 can be interpreted as the battery 101a, the battery 101b, or the battery pack housing.

[0084] <BMU> As shown in FIGS. 1A and 1B, the battery control system 10 according to one aspect of the present invention includes a BMU 112. As shown in FIGS.

[0085] The BMU 112 is electrically connected to the driving battery 101, and in this embodiment, since the driving battery 101 has the battery 101a and the battery 101b, the BMU 112 has a circuit 103a corresponding to the battery 101a and a circuit 103b corresponding to the battery 101b. In other words, the BMU 112 has the circuits 103a and 103b corresponding to the batteries of the driving battery 101.

[0086] As described above in <Configuration Example 1 of Battery Control System>, the circuits 103a, 103b, etc., included in the BMU 112 can transfer power between the batteries 101a and 101b depending on the temperature. To achieve this, the circuits 103a and 103b each preferably include a transformer and a switch electrically connected to the transformer. The transformer electrically connected to the input side of the battery has a configuration in which a primary coil and a secondary coil are wound around a common iron wire, and when a current flows through one of the coils, an induced electromotive force is generated in the other coil. The current flowing through one of the coils is controlled by a switch electrically connected to the other coil. Specifically, when the switch is turned on, a constant current flows through one of the coils, and the switch can be repeatedly turned on and off until the current reaches a level corresponding to the amount of current to be transferred between the batteries.

[0087] When power from battery 101a is transferred to battery 101b, a current corresponding to the amount of power transferred is supplied to circuit 103b via circuit 103a, and a current is supplied to battery 101b via circuit 103b. When power from battery 101b is transferred to battery 101a, a current corresponding to the amount of power transferred is supplied to circuit 103a via circuit 103b, and a current is supplied to battery 101a via circuit 103a.

[0088] Note that the circuits 103a and 103b may be provided in other units instead of in the BMU 112. Specific configurations of the circuits 103a and 103b will be described later.

[0089] <DCDC Circuit> The battery control system 10 shown in FIG. 1B includes a DCDC circuit 105, unlike the battery control system 10 shown in FIG. 1A.

[0090] The DCDC circuit 105 is electrically connected to the driving battery 101, and since the present embodiment has two types of batteries 101a and 101b, the DCDC circuit 105 has a DCDC circuit 105a corresponding to the battery 101a and a DCDC circuit 105b corresponding to the battery 101b. That is, the DCDC circuit 105 has a DCDC circuit 105a and a DCDC circuit 105b corresponding to the batteries of the driving battery 101, and these are electrically connected to the output side of the batteries.

[0091] As described above in <Configuration Example 2 of Battery Control System>, the DCDC circuit 105a and the DCDC circuit 105b can make the output from the battery 101a higher than the output from the battery 101b. To achieve this, the DCDC circuit 105a and the DCDC circuit 105b each preferably have at least a coil and a switch electrically connected to the coil. Other specific examples of the DCDC circuit 105a and the DCDC circuit 105b will be described later.

[0092] Furthermore, the DCDC circuit 105 can be used to make the output voltages from the battery 101a and the battery 101b uniform.

[0093] In the above <Configuration Example 2 of Battery Control System>, it has been described that the output from each battery is made different depending on the temperature, but if the output voltages from each battery are made uniform by the DCDC circuit 105 and the output current of battery 101a is different from the output current of battery 101b, the output from each battery can be made different depending on the temperature. In order to make the output currents different, it is preferable that the DCDC circuit 105a and the DCDC circuit 105b each have the above-mentioned coil and a switch electrically connected to the coil.

[0094] <Specific Example of Battery Control System> Next, FIG. 2 shows a specific example of the battery control system 10 shown in FIG. 1B.

[0095] 1B, the battery control system 10 preferably includes a control circuit 18 and switches SW11 to SW15 to which a signal from the temperature sensor 102 is input. Although the control circuit 18 is provided within the battery control system 10 in FIG. 2, the present invention is not limited to this and the control circuit 18 may be provided outside the control system 10. For example, the control circuit 18 may be provided in an ECU (Electronic Control Unit).

[0096] As described above, when a thermistor is used as the temperature sensor 102, a signal related to the resistance value is input to the control circuit 18, and the control circuit 18 can detect the temperature corresponding to the resistance value. An example of the configuration of a temperature sensor using a thermistor will be described later.

[0097] Next, the configuration of SW11 to SW15 will be described with reference to FIG. 2 . SW11 is preferably located between the input and the circuit 103a and between the input and the circuit 103b, SW12 is preferably located between the circuit 103a and the battery 101a, and SW13 is preferably located between the circuit 103b and the battery 101b. SW14 is preferably located between the battery 101a and the DCDC circuit 105a, and SW15 is preferably located between the battery 101b and the DCDC circuit 105b. The above-described SW11 to SW15 are controlled by a control circuit 18. Specifically, the on / off of SW11 to SW15 is controlled in accordance with the temperature input to the control circuit 18. Switching elements such as transistors can be used for SW11 to SW15.

[0098] <Charging> A case where the battery 101a and the battery 101b are charged will be described. When charging the battery 101a, at least SW11 and SW12 are turned on in accordance with the temperature obtained by the temperature sensor 102. When charging the battery 101b, at least SW11 and SW13 are turned on in accordance with the temperature obtained by the temperature sensor 102. In the battery control system 10 of one embodiment of the present invention, the battery 101a can be charged via the circuit 103a, and the battery 101b can be charged via the circuit 103b. Note that SW14 and SW15 are preferably turned off during charging.

[0099] It is also possible to charge battery 101a preferentially depending on the temperature, specifically, when the temperature is 25°C or higher. In this case, for example, SW11 and SW12 are turned on and SW13 is turned off. When charging battery 101a at 25°C or higher, if battery 101b is cooled simultaneously with, immediately before, or immediately after charging, battery 101b can also be charged. Note that 25°C is an example.

[0100] When the battery 101a is given priority for charging according to the temperature, if the battery 101a that started charging first generates heat, the heat can be used to warm the battery 101b that will be charged later. When warming the battery 101b, it is preferable to manage the temperature taking into consideration the battery characteristics of the battery 101b.

[0101] Furthermore, depending on the temperature, specifically, when the temperature is -10°C or lower, it is also possible to charge battery 101b with priority. In this case, for example, SW11 and SW13 may be turned on and SW12 may be turned off. When charging battery 101b at -10°C or lower, battery 101a can also be charged by warming battery 101a simultaneously with, immediately before, or immediately after charging. Note that -10°C is an example.

[0102] When the battery 101b is given priority for charging according to the temperature, if the battery 101b that started charging first generates heat, the heat can be used to warm the battery 101a that will be charged later. When warming, it is advisable to manage the temperature taking into consideration the battery characteristics of the battery 101a.

[0103] Furthermore, either the battery 101a or the battery 101b may be charged first, but if either one of them can be charged quickly, then that one can be charged first, and the other can be charged later.

[0104] In this way, the battery control system 10 according to one aspect of the present invention makes it possible to charge each battery in an appropriate state depending on the temperature.

[0105] <During Discharge> Next, a description will be given of the case where batteries 101a and 101b are discharged. When discharging battery 101a, at least SW14 is turned on in accordance with the temperature obtained by temperature sensor 102. When discharging battery 101b, at least SW15 is turned on in accordance with the temperature obtained by temperature sensor 102. During discharge, it is advisable to turn off at least SW12 and SW13, but SW11 may be either off or on.

[0106] As described above in <Configuration Example 2 of Battery Control System>, the battery control system 10 can use the DCDC circuit 105a and the DCDC circuit 105b to control the output from the battery 101a so that it differs from the output from the battery 101b depending on the temperature. The output from the battery may be interpreted as discharging from the battery. Furthermore, the DCDC circuit 105a and the DCDC circuit 105b can make the output voltage of the battery 101a and the output voltage of the battery 101b the same.

[0107] It is also possible to discharge only battery 101a in accordance with the temperature. In this case, for example, SW14 may be turned on and SW15 may be turned off. It is also possible to discharge only battery 101b in accordance with the temperature. In this case, for example, SW15 may be turned on and SW14 may be turned off.

[0108] In this way, the battery control system 10 according to one aspect of the present invention makes it possible to discharge each battery in an appropriate state depending on the temperature.

[0109] <During Transfer> Next, a case where the power of one of the batteries 101a and 101b is transferred to the other will be described. In order to transfer the output from the battery 101a to the battery 101b in accordance with the temperature obtained by the temperature sensor 102, SW12 and SW13 are turned on, and the battery 101a is electrically connected to the battery 101b via the circuits 103a and 103b. When transferring the output from the battery 101a to the battery 101b in accordance with the temperature obtained by the temperature sensor 102, SW12 and SW13 should also be turned on. Note that at least SW11, SW14, and SW15 should be turned off during transfer.

[0110] Depending on the temperature, the power of the battery 101b can be transferred to the battery 101a. For example, it is possible to transfer part or all of the power of the battery 101b to the battery 101a.

[0111] Depending on the temperature, the power of the battery 101a can be transferred to the battery 101b. For example, it is possible to transfer a part or all of the power of the battery 101a to the battery 101b.

[0112] In this way, the battery control system 10 according to one aspect of the present invention makes it possible to use each battery in an appropriate state depending on the temperature.

[0113] <Diodes> Furthermore, the battery control system 10 of one embodiment of the present invention preferably includes a diode 17a and a diode 17b. As shown in FIG. 2 , the diode 17a is preferably located between the DCDC circuit 105a and the output. By including the diode 17a, the current flow, i.e., the output direction, can be limited to one direction. Similarly, the diode 17b is preferably located between the DCDC circuit 105b and the output. By including the diode 17b, the current flow, i.e., the output direction, can be limited to one direction.

[0114] While a specific example of the battery control system 10 shown in Fig. 1B has been described using Fig. 2, the battery control system 10 shown in Fig. 1A corresponds to the system in Fig. 2 from which at least the DCDC circuits 105a and 105b have been omitted. That is, the battery control system 10 shown in Fig. 1A may also include SW14, SW15, diode 17a, and diode 17b.

[0115] <Configuration Example of Temperature Sensor Using Thermistor> Next, a configuration using a thermistor, typically an NTC thermistor, for the temperature sensor 102 will be described. For example, as shown in FIG. 3A, the thermistor 16a may be positioned near or in contact with the battery 101a. Preferably, the contact portion of the thermistor 16a is in contact with the battery 101a. In FIG. 3A, the thermistor 16a is electrically connected to a resistive element 23a. Changes in the resistance value of the thermistor 16a can be detected by using a resistive divider between two resistive elements. Because a resistive divider is used, the thermistor 16a is preferably electrically connected to a wiring at a constant potential.

[0116] Furthermore, a buffer amplifier 19a is electrically connected to the thermistor 16a, and the signal can be amplified by the buffer amplifier 19a. The output from the buffer amplifier 19a is converted into a digital signal via an analog-to-digital conversion circuit (A / D circuit) 20a and input to the control circuit 18.

[0117] The battery 101b and thermistor 16b may also have a similar configuration for the temperature sensor 102.

[0118] Specifically, the thermistor 16a can detect voltage (denoted as Va in FIG. 3A), and data can be obtained, for example, as shown in FIG. 3B, where the horizontal axis represents temperature and the vertical axis represents voltage (Va). Based on this data, the control circuit 18 can manage the temperature of the battery 101a.

[0119] Similarly, the thermistor 16b can obtain data such as that shown in FIG. 3B, and the control circuit 18 can manage the temperature of the battery 101b.

[0120] Furthermore, by combining the data from the thermistor 16a and the thermistor 16b, it is possible to obtain the average temperature of the battery 101a and the battery 101b.

[0121] 4A shows an example in which a differentiator 21a is provided instead of the A / D circuit 20a in a configuration relating to a battery 101a and a temperature sensor 102 having a thermistor 16a, etc. Similarly, a differentiator 21b can be provided instead of the A / D circuit 20b in a configuration relating to a temperature sensor 102 having a battery 101b and a thermistor 16b, etc., but this is not shown in FIG.

[0122] 4B shows details of the differentiator 21a and the control circuit 18. The differentiator 21a includes a sample-and-hold circuit 300, a comparator 301, a DA converter 302, a successive approximation register 303, a second control circuit 304, a clock generation circuit 305, and the like.

[0123] 4B can hold the voltage (analog value) output from the buffer amplifier 19a in a sample-and-hold circuit 300. While the analog value is being converted into a digital value by a comparator 301 and a successive approximation register 303, the sample-and-hold circuit 300 preferably holds the analog value. The transistor included in the sample-and-hold circuit 300 can be an OS transistor. An OS transistor is a transistor in which an oxide semiconductor layer is applied to an active layer.

[0124] The off-state current of an OS transistor is, for example, 1 aA (1×10) per 1 μm channel width at room temperature. −１８ A) Below, 1zA (1×10 −２１ A) or less, or 1yA (1 x 10 −２４ Note that the off-state current of a Si transistor per 1 μm of channel width at room temperature can be 1 fA (1×10 −１５ A) More than 1pA (1×10 −１２ A) or less. Therefore, it can be said that the off-state current of an OS transistor is about 10 orders of magnitude lower than that of a Si transistor. A transistor with such a low off-state current is suitable for the sample-and-hold circuit 300.

[0125] The value output from the sample-and-hold circuit 300 is input to the comparator 301 and compared with the data in the successive approximation register 303 via the second control circuit 304. The successive approximation register 303 outputs digital data in which the analog voltage value is divided into at least two or more parts and each part is assigned to a respective bit. Before being input to the comparator 301, the digital data may be converted from digital to analog via a DA converter 302. The comparator 301 then compares the data from the sample-and-hold circuit 300 with the data from the successive approximation register 303. If the data match, the comparator 301 outputs a 0, and if the data do not match, the comparator 301 outputs a 1. The value 0 or 1 is output to the second control circuit 304, and data determined to match is output as a digital value from the successive approximation register 303 to the control circuit 18. In this way, the voltage converted into a digital value can be detected.

[0126] Furthermore, data DataA, data DataB, and data DataC may be output from the second control circuit 304 to the control circuit 18. Data DataA may be assigned a sign (e.g., +) indicating that the temperature is dropping, or a sign (e.g., -) indicating that the temperature is dropping. Data DataB may be, for example, data related to time. For example, time may be counted based on a clock signal (CKL1) input to the differentiator 21a, and output as the time data. Data DataC is a flag in the event of an error. For example, if the temperature and voltage relationship shown in the graph of FIG. 3B is satisfied, a relationship of approximately 5°C change per approximately 50 mV can be derived. Therefore, using the time data, error data can be assigned based on the time required for a 5°C change per 50 mV. The second control circuit 304 can determine that an error has occurred if this standard is exceeded and set a flag.

[0127] 4A and 4B, the temperature of the battery 101a can be obtained using a temperature sensor having a differentiator, etc. Similarly, the temperature of the battery 101b can be obtained. Furthermore, the average temperature of the batteries 101a and 101b can also be obtained.

[0128] Furthermore, as shown in FIGS. 4A and 4B, it is preferable to provide a difference calculator using a temperature sensor or the like, as this allows error processing.

[0129] <Specific Example of Circuit 103> Next, the circuit configurations of the circuit 103a and the circuit 103b will be described with reference to Fig. 5. Note that the circuit 103b has a similar circuit configuration to the circuit 103a, and therefore the description of the circuit 103b will be simplified in some cases.

[0130] The circuit 103a includes a transformer 22a, which may be, for example, an insulating transformer. One coil Wa1 of the transformer 22a may be referred to as the primary circuit of the transformer 22a, and the other coil Wa2 of the transformer 22a may be referred to as the secondary circuit of the transformer 22a. In the primary circuit, one end of the coil Wa1 is electrically connected to SW12, and the other end is electrically connected to SW25a. SW12 is also electrically connected to the battery 101a.

[0131] Similarly to the primary circuit, the secondary circuit of the transformer 22a also has a coil Wa2 and a switch SW26a, one end of the coil Wa2 being electrically connected to the switch SW11 and the other end being electrically connected to the switch SW26a.

[0132] When a current flows through one coil of the transformer 22a, for example, coil Wa1, a magnetic field generated from that coil generates an induced electromotive force in the other coil, for example, coil Wa2. This phenomenon is sometimes called mutual induction. As a result, a voltage is induced in the other coil, for example, coil Wa2, causing a current to flow through coil Wa2. In this embodiment, the number of turns of coil Wa1 is the same as that of coil Wa2, but the numbers of turns may be different.

[0133] In the circuit 103a, it is preferable to use switching elements such as MOS transistors for the switches SW25a and SW26a. Furthermore, a resistive element may be electrically connected to the switch SW25a for rectification. Similarly, a resistive element may be electrically connected to the switch SW26a. The timing at which the current caused by the induced electromotive force flows can be controlled by turning the switches SW25a and SW26a on and off.

[0134] The circuit 103b has a configuration similar to that of the circuit 103a, except that one end of the coil Wb1 in the circuit 103b is electrically connected to the switch SW13, which is also electrically connected to the battery 101b.

[0135] <Charging> A case where the battery 101a is charged will be described. The circuit 103a including the transformer 22a and the circuit 103b including the transformer 22b may be used as a flyback converter or a forward converter.

[0136] First, the case of a flyback converter will be described. When SW26a is turned on and current flows through coil Wa2, the generated magnetic flux magnetizes the iron wire (also referred to as the core) of circuit 103a. The magnetization of the core is sometimes referred to as energy storage. When SW25a is turned off, the voltage of coil Wa2 drops and no current flows through coil Wa1. When SW26a is then turned off, the energy stored in the core is released and current flows through coil Wa1.

[0137] If SW12 is on, the current flowing through the coil Wa1 is supplied to the battery 101a, enabling charging.

[0138] The battery 101b is charged in the same manner as the battery 101a.

[0139] Next, the case of a forward converter will be described. When SW26a is turned on, an induced electromotive force is generated in coils Wa1 and Wa2. The induced electromotive force is sometimes referred to as electromotive force. Current flows in coils Wa1 and Wa2 in accordance with the induced electromotive force. The direction of the current is controlled using a diode, so that energy is stored in a choke coil, for example. After that, when SW26a is turned off, the energy stored in the choke coil is released, and current flows in the direction controlled by the diode.

[0140] If SW12 is on, the current flowing through the choke coil is supplied to the battery 101a, enabling charging.

[0141] That is, the circuit 103a includes a diode and a choke coil.

[0142] The battery 101b is charged in the same manner as the battery 101a.

[0143] <During Transfer> Next, a case where power from one of the batteries 101a and 101b is transferred to the other will be described with reference to Fig. 6. Fig. 6 shows the circuit configuration shown in Fig. 5 with arrows (Xa, Ya, Xb, and Yb) indicating the direction of current.

[0144] The case where power from battery 101a is transferred to battery 101b will be described. First, SW25a and SW12 are turned on to extract the current to be transferred from battery 101a. In FIG. 6, an arrow Ya indicates the current from battery 101a flowing through coil Wa1 of transformer 22a. The current flowing as indicated by arrow Ya may be referred to as I (discharge). The current to be transferred from battery 101a can be determined according to the temperature. The current to be transferred can also be determined according to the SOC of battery 101a. The SOC indicates the state of charge rate of the battery cell.

[0145] When SW25a is turned off and SW26a is turned on, a current corresponding to I (discharge) is generated in coil Wa2. In Fig. 6, an arrow Xa is added to the current flowing in coil Wa2 of transformer 22a, and the current flowing as indicated by arrow Xa is sometimes referred to as I (return), which is also called the return of charge.

[0146] Because SW26b is on, a current corresponding to I(return) flows through the coil Wb2 of the transformer 22b of the circuit 103b. In Figure 6, the current flowing through the coil Wb2 is indicated by an arrow Xb, and the current flowing as indicated by the arrow Xb is sometimes referred to as I(supply), also known as the supply of charge. The current indicated by the arrow Xb has the same value as the current indicated by the arrow Xa.

[0147] Thereafter, when SW26b is turned off and SW25b is turned on, a current corresponding to I(supply) flows through the coil Wb1 of the transformer 22b. In Fig. 6, the current flowing through the coil Wb2 is indicated by an arrow Yb, and the current flowing as indicated by the arrow Yb is sometimes referred to as I(charge).

[0148] If SW13 is on, the I(charge) is used to charge the battery 101b, thus transferring power from the battery 101a to the battery 101b.

[0149] Although the case where the power of the battery 101a is transferred to the battery 101b has been described, it is also possible to transfer the power of the battery 101b to the battery 101a, in which case the current flow will be in the opposite direction to that described above.

[0150] <Specific Example of DCDC Circuit> Next, a configuration example of a DCDC circuit will be described with reference to FIGS. 7A to 7E.

[0151] 7A shows a SW 14 controlled by a control circuit 18 and a DCDC circuit 105a electrically connected to the SW 14. An output from a battery 101a (not shown in FIG. 7A) is supplied to the DCDC circuit 105a via the SW 14. The DCDC circuit 105a has a coil 31a, which can amplify the output of the battery 101a, specifically the output voltage.

[0152] The DCDC circuit 105a has a switch, specifically a transistor 32a, electrically connected to the coil 31a, and the transistor 32a is controlled by the control circuit 18. The transistor 32a, electrically connected to the coil 31a, repeatedly turns on and off, thereby amplifying the output voltage.

[0153] The DCDC circuit 105a preferably includes a diode 33a electrically connected to the coil 31a. The diode 33a is preferably provided to rectify the signal.

[0154] The DCDC circuit 105a further includes a sense circuit 34a located at the output of the diode 33a. The sense circuit 34a can output voltage or current data of the sense circuit 34a to the control circuit 18. Based on this data, the control circuit 18 controls the on / off of the transistor 32a so that the amplified output voltage falls within an appropriate range. The output voltage amplified to the appropriate range is then output to the diode 17a and supplied to the drive motor 108 via the diode 17a.

[0155] The DCDC circuit 105b has a configuration similar to that of the DCDC circuit 105a, and therefore a description thereof will be omitted. In the DCDC circuit 105b, an output voltage amplified to an appropriate range is output to the diode 17b, and is supplied to the drive motor 108 via the diode 17b. The appropriate range is preferably a voltage appropriate for rotating the drive motor 108, and is often higher than the voltage obtained from the batteries 101a and 101b.

[0156] 7B and 7C show connection examples of the sense circuit 34a. As shown in Fig. 7B, the sense circuit 34a can have a current sense circuit 35 and a voltage sense circuit 36 ​​connected in series thereto. As shown in Fig. 7C, the sense circuit 34a can have a circuit in which the current sense circuit 35 and the voltage sense circuit 36 ​​are connected in parallel.

[0157] 7D shows a specific example of the current sense circuit 35. The current sense circuit 35 may include a resistor element 37 and an operational amplifier 38 electrically connected to both ends of the resistor element 37. The output value of the operational amplifier 38 is voltage data, and this data is output to the control circuit 18. For example, if the voltage data is too high, the transistor 32a is controlled to lower the voltage, and if the voltage data is too low, the transistor 32a is controlled to raise the voltage. Depending on the current sense circuit 35, it may also be possible to output current data to the control circuit 18.

[0158] 7E shows a specific example of the voltage sense circuit 36. The voltage sense circuit 36 ​​preferably includes resistor elements 39a and 39b. Voltage data obtained by resistive division is output to the control circuit 18. For example, if the voltage data is too high, the transistor 32a is controlled to lower the voltage, and if the voltage data is too low, the transistor 32a is controlled to raise the voltage. Depending on the voltage sense circuit 36, current data can also be output to the control circuit 18.

[0159] The battery control system according to one aspect of the present invention makes it possible to control the output from each battery in accordance with temperature. Also, the battery control system according to one aspect of the present invention makes it possible to exchange energy between the batteries, i.e., transfer energy, in accordance with temperature.

[0160] According to one aspect of the present invention, it is possible to efficiently use each battery and suppress unevenness in the state of deterioration. Furthermore, according to another aspect of the present invention, it is possible to supply stable power.

[0161] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0162] Embodiment 2 In this embodiment, a new configuration of a battery control system according to one embodiment of the present invention will be described.

[0163] When the battery 101a and the battery 101b are combined into a battery pack, the states of the battery cells may vary. The states of the battery cells change differently between the battery 101a and the battery 101b, which have different battery characteristics. Therefore, in the battery control system 10 according to one embodiment of the present invention, an example will be described in which the BMU 112 is provided with a balancing circuit 104a and a balancing circuit 104b to manage the states of the battery cells.

[0164] The battery control system 10 shown in Fig. 8A differs from that shown in Fig. 1A in that the BMU 112 is provided with a balancing circuit 104a and a balancing circuit 104b. The battery control system 10 shown in Fig. 8B differs from that shown in Fig. 1B in that the BMU 112 is provided with a balancing circuit 104a and a balancing circuit 104b.

[0165] FIG. 9A shows the battery cell states, specifically, the SOCs, of the battery 101a (battery 101a(1), battery 101a(2), battery 101a(m)) that comprise the battery pack. The SOC differences are represented by the areas of the shaded regions. When the deterioration rates of battery 101a(1) and battery 101a(2) differ, the SOCs of the two batteries differ.

[0166] 9A also shows balancing circuits 104a (balancing circuit 104a(1), balancing circuit 104a(2), and balancing circuit 104a(m)) included in the BMU 112. The balancing circuit 104a(1) is electrically connected to the battery 101a(1) and is capable of grasping the current state of the battery 101a(1), specifically, the SOC. Similarly, the balancing circuits 104a(2) and subsequent circuits are electrically connected to the batteries 101a(2) and subsequent circuits, respectively, and are therefore capable of grasping the current SOC of the battery 101a.

[0167] 9B shows the relationship between battery 101b (battery 101b(1), battery 101b(2), battery 101b(n)) having a battery pack and balancing circuit 104b (balancing circuit 104b(1), balancing circuit 104b(2), balancing circuit 104b(n)). As in FIG. 9A, the current SOC of battery 101b can be determined by balancing circuit 104b.

[0168] Furthermore, after determining the SOC, it is advisable to equalize the SOC of each battery cell (referred to as cell balancing). For example, before charging the drive battery 101, it is advisable to perform cell balancing on the battery 101a. Also, before charging the drive battery 101, it is advisable to perform cell balancing on the battery 101b.

[0169] Furthermore, it is preferable to perform cell balancing on the batteries 101a and 101b before charging the driving battery 101. It is preferable that the cell balancing process makes the SOC of the battery 101b equal to the SOC of the battery 101a, but this is not necessary.

[0170] 9A and 9B, the number of battery cells in battery 101a is m and the number of battery cells in battery 101b is n, but m and n are natural numbers equal to or greater than 1. Furthermore, m, which is the number of battery cells, may be equal to n (m=n). Furthermore, m, which is the number of battery cells, may be greater than n (m>n). Furthermore, m, which is the number of battery cells, may be less than n (m<n).

[0171] In Figures 9A and 9B, the size of battery 101a and the size of battery 101b are shown to be equal, but the size of battery 101a may be different from the size of battery 101b, for example, the size of battery 101a may be larger than the size of battery 101b.

[0172] The battery 101a may be a laminated battery cell, which will be described later, and the battery 101b may be a prismatic battery cell or a cylindrical battery cell, which will be described later.

[0173] The battery 101a may be a rectangular battery cell, which will be described later, and the battery 101b may be a laminated battery cell or a cylindrical battery cell, which will be described later.

[0174] The battery 101a may be a cylindrical battery cell, which will be described later, and the battery 101b may be a laminated battery cell or a prismatic battery cell, which will be described later.

[0175] Considering the size or shape of the batteries, it is preferable that the SOC of the battery 101b is made equal to the SOC of the battery 101a through cell balancing, but this is not necessary.

[0176] In this way, the battery control system 10 according to one aspect of the present invention can grasp the state of each battery, and therefore can use each battery in an appropriate state depending on the temperature.

[0177] <Balance Circuit> FIG. 10 shows a concrete example of the balance circuit 104a, typically the balance circuit 104a(1) of FIG. 9A.

[0178] The balancing circuit 104a(1) has a transformer 220a, and a switch 250a and a switch SW260a that control the transformer 220a. The transformer 220a has coils Wa10 and Wa20, and when it is determined that the battery 101a(1) should be charged based on its SOC, a current is supplied to the battery 101a(1) via the coil Wa10. When it is determined that the battery 101a(1) should be discharged based on its SOC, a current is released from the battery 101a(1) via the coil Wa20.

[0179] The balance circuit 104a(2) and subsequent circuits can have the same configuration as the balance circuit 104a(1), and therefore the description thereof will be omitted.

[0180] The balance circuit 104b can have a configuration similar to that of the balance circuit 104a, and therefore a description thereof will be omitted.

[0181] As described above, the battery control system 10 according to one aspect of the present invention can perform cell balancing for each battery, thereby enabling efficient charging of the battery pack according to the temperature.

[0182] Furthermore, based on the above-described understanding of the SOC, the BMU 112 and the like can execute a remaining battery capacity estimation process. For example, the remaining battery capacity estimation process can be performed by estimating the SOC-OCV characteristics of each battery cell, estimating the FCC, or estimating the internal resistance. OCV stands for open circuit voltage. FCC stands for full charge capacity. The internal resistance can be estimated from the voltage and current between the positive and negative terminals of the battery cell.

[0183] In this way, the battery control system 10 according to one aspect of the present invention can control the power output from each battery according to the temperature, and can use each battery in an appropriate state according to the temperature.

[0184] Embodiment 3 In this embodiment, an electric vehicle (EV) equipped with a battery control system according to one embodiment of the present invention will be described.

[0185] 11A , an electric vehicle 100 of this embodiment includes a drive battery 101, a temperature sensor 102, a BMU 112, a DCDC circuit 105, a charge control circuit 106, an inverter 107, a drive motor 108, a normal charge port 109 a, a quick charge port 109 b, a charger 110, tires 113, a heater 114, a 12V battery 116, and lights 119. The heater 114 includes a heater that controls the air conditioning inside the vehicle and a heater that controls the temperature of the drive battery 101.

[0186] The electric vehicle 100 in Fig. 11A has the battery control system 10 shown in Fig. 1B of the above embodiment. The electric vehicle 100 can transfer power between the battery 101a and the battery 101b as in at least <Configuration Example 1 of Battery Control System>. Furthermore, the electric vehicle 100 can make the output from the battery 101a different from the output from the battery 101b as in <Configuration Example 2 of Battery Control System>. Furthermore, the electric vehicle 100 can be controlled as in <Configuration Example 3 of Battery Control System>.

[0187] The electric vehicle 100 in Fig. 11A may also have the battery control system 10 shown in Fig. 1A of the above embodiment. The electric vehicle 100 in Fig. 11A may also have the battery control system 10 shown in Fig. 8A and Fig. 8B of the above embodiment.

[0188] The output voltage from the driving battery 101 of the electric vehicle 100 is set to 300 V or more and 900 V or less, preferably 350 V or more and 800 V or less. In this embodiment, the combined voltage of the battery 101a and the battery 101b is set to 3300 V or more and 900 V or less, preferably 350 V or more and 800 V or less.

[0189] The output voltage can be determined according to the number of battery cells in battery 101a and battery 101b. For example, battery 101a is an assembled battery having 100 battery cells, and may have three such assembled batteries. The 100 battery cells are connected in series, and the three assembled batteries are connected in parallel. Battery 101b also has an assembled battery having multiple battery cells, and may further have multiple such assembled batteries. Using this configuration, the output voltage from drive battery 101 can be increased.

[0190] Furthermore, the output voltage can be increased using the DCDC circuit 105. For example, even if the output voltage from the drive battery 101 is less than 600 V, the DCDC circuit 105 can increase the voltage to between 600 V and 900 V, preferably between 650 V and 850 V. The increased voltage is output to the drive motor 108.

[0191] The normal charging port 109a or the fast charging port 109b in FIG. 11A can be made to correspond to the input of the battery control system in FIG. 1B, and the drive motor 108 in FIG. 11A can be made to correspond to the output of the battery control system.

[0192] Next, the battery pack 201 will be described. The battery pack 201 is a battery unit that can be installed in the electric vehicle 100. The battery pack 201 of this embodiment shown in FIG. 11A includes a drive battery 101, a temperature sensor 102, a BMU 112, and the like. The battery pack 201 also includes a cooling device, etc., but these are not shown in FIG. 11A . The cooling device may be a water-cooled or air-cooled system. The battery pack 201 has a housing made of iron or the like, and the housing is designed to be highly airtight to prevent electrical failure due to water ingress. Considering the configuration of the battery pack 201, the battery control system shown in FIG. 1A of the above embodiment can also be considered as the battery control system included in the battery pack 201 of FIG. 11A.

[0193] It is also possible to directly mount the driving battery 101, the temperature sensor 102, the BMU 103, etc. on the electric vehicle 100 without configuring a unit called the battery pack 201.

[0194] 11B shows the external appearance of electric vehicle 100 according to this embodiment. Fig. 11B shows battery pack 201 stored in the floor, and also shows tires 113, lights 119, normal charging port 109a, and quick charging port 109b, among other things, that can be seen from the exterior. It is preferable that light 119 is supplied with power from drive battery 101.

[0195] <Charging Port, On-Board Charger (Charger), Charging Device (Charging Station)> As shown in FIG. 11A , an electric vehicle 100 according to one embodiment of the present invention has a normal charging port 109a. The normal charging port 109a is electrically connected to a charging station, enabling charging of the drive battery 101 from the charging station. The normal charging port 109a is electrically connected to a charger 110, which has a conversion device such as an AC-DC circuit. The AC-DC circuit or the like can be used to convert alternating current from the charging station to direct current. That is, during normal charging, the electric vehicle 100 performs the process of converting alternating current to direct current. Therefore, normal charging may require a long charging time.

[0196] 11A, the charger 110 is electrically connected to the charge control circuit 106, and power is supplied from the charge control circuit 106 to the driving battery 101. The charge control circuit 106 will be described later.

[0197] 11A , an electric vehicle 100 according to one embodiment of the present invention has a rapid-charge port 109b, and the electric vehicle 100 can also be charged via the rapid-charge port 109b. In rapid charging, a process of converting AC current to DC current is performed at the charging station. The charging station can be equipped with a large-scale circuit for this process, and this process can be performed at high speed, thereby shortening the charging time during rapid charging.

[0198] As mentioned above, the battery voltage required for the electric vehicle 100 is increasing, and therefore the number of battery cells included in the drive battery 101 is on the rise. Performing normal charging on a battery pack having a large number of battery cells can take a considerable amount of time. Therefore, rapid charging is more suitable than normal charging for charging an electric vehicle 100 equipped with a high battery voltage.

[0199] In this embodiment, one of the batteries 101a and 101b may be configured to be capable of rapid charging, and the other may be configured to be capable of normal charging. For example, the battery 101a is a normal temperature battery and therefore can be rapid charged, while the battery 101b is a low temperature battery and therefore normal charging is more suitable than rapid charging.

[0200] The quick charge port 109b is electrically connected to the charge control circuit 106 without going through the charger 110, and power is supplied from the charge control circuit 106 to the driving battery 101. The charge control circuit 106 will be described later.

[0201] The charging station may be a home power source or a charging station provided at a commercial facility, and charging stations capable of rapid charging are often installed at such charging stations.

[0202] In addition, the charging method or connector standard may be a predetermined system such as CHAdeMO (registered trademark) or Combo.

[0203] <Charge Control Circuit, Inverter, and Drive Motor> The electric vehicle 100 according to one embodiment of the present invention includes a charge control circuit 106. The charge control circuit 106 may include a current sensor, a relay circuit, a fuse, and the like. As the relay circuits, the charge control circuit 106 may include a relay circuit for rapid charging, a relay circuit for normal charging, and a main relay circuit. Each of the relay circuits is electrically connected to a current sensor, and can forcibly terminate rapid charging or normal charging when the current sensor or the like determines that the current exceeds a predetermined current value. The charge control circuit 106 allows the electric vehicle 100 to be safely charged. Although FIG. 11A illustrates the charge control circuit 106 as being separate from the battery pack 201, the charge control circuit 106 may be incorporated in the battery pack 201.

[0204] The charging control circuit 106 can control the output voltage of the drive battery 101, for example, a high-voltage system of 300 V to 850 V, and more preferably 400 V to 800 V. The charging control circuit 106 can also control electronic components in a high-voltage system (any voltage higher than 12 V, such as 42 V or 48 V). For example, the charging control circuit 106 controls on-board components of a 42 V system (such as the heater 114 or electric power steering).

[0205] The charging control circuit 106 is also supplied with power from the drive battery 101 via the DCDC circuit 105. The DCDC circuit 105 adjusts the voltage to a level suitable for powering the drive motor 108. That is, if the voltage output from the drive battery 101 is high, the DCDC circuit 105 converts it to a low voltage. The power is then transferred to the inverter 107, which converts the direct current into alternating current. That is, the inverter 107 is a type of conversion device.

[0206] The drive motor 108 receives an appropriate amount of power from the inverter 107 and can rotate the tires 113 .

[0207] 11A , an electric vehicle 100 according to one embodiment of the present invention includes a 12V battery 116. A lead battery can be used as the 12V battery 116. The 12V battery 116 is used when starting the electric vehicle 100. The 12V battery 116 can also supply power to 12V-based on-board components (such as turn signals or audio). Such a 12V battery may be referred to as an auxiliary battery.

[0208] The output from the 12V battery 116 may be supplied to the DCDC circuit 105c. That is, the DCDC circuit 105 may include DCDC circuits 105a to 105c.

[0209] An electric vehicle equipped with a battery control system according to an embodiment of the present invention can control the energy output of each battery according to temperature. Also, an electric vehicle equipped with a battery control system according to an embodiment of the present invention can exchange energy between the batteries, i.e., transfer energy, according to temperature.

[0210] According to one aspect of the present invention, it is possible to efficiently use each battery of an electric vehicle, thereby suppressing unevenness in the state of deterioration. Furthermore, according to another aspect of the present invention, it is possible to supply stable power to an electric vehicle.

[0211] <First Use Example> Next, a first use example of the battery control system or the like according to one embodiment of the present invention will be described with reference to FIG.

[0212] In step S51, the charging station plug is inserted into the charging port 109, in step S52 charging of the batteries 101a and 101b begins, in step S53 the plug is removed from the charging port 109, and in step S54 the electric vehicle 100 starts to travel.

[0213] In step S55, temperature information is obtained from the temperature sensor 102, and in step S56, it is determined whether the temperature is equal to or higher than Tr. Tr is within a first temperature range of the battery 101a and can be determined according to specifications. For example, Tr can be the temperature at which the output of the battery 101a falls to 80% or less of the maximum output. For example, if the temperature is 0°C, it is determined in step S55 whether the temperature is equal to or higher than 0°C.

[0214] If the temperature is equal to or higher than Tr (YES), in step S56, the output of battery 101a is controlled to be greater than the output of battery 101b. The output of battery 101b may be stopped in step S56. For example, if the temperature is 25°C, the output of battery 101b may be stopped and only the output of battery 101a may be supplied to the drive motor. When the temperature is equal to or higher than 25°C and battery 101b is not operating or has deteriorated significantly, it is preferable to use only battery 101a as the drive battery 101.

[0215] If the temperature is below Tr (NO), control is performed in step S58 to make the output of battery 101b greater than the output of battery 101a. The output of battery 101a may be stopped in step S58. For example, if the temperature is -20°C, the output of battery 101a may be stopped and only the output of battery 101b may be supplied to the drive motor. When the temperature is -20°C or lower and battery 101a does not operate or has deteriorated significantly, it is preferable to use only battery 101b as the drive battery 101.

[0216] By operating the batteries 101a and 101b appropriately in accordance with the temperature in this manner, it is possible to supply appropriate power to the drive motor 108 while suppressing the deterioration of each battery.

[0217] Next, in step S59, the electric vehicle 100 is stopped. Stopping means that the vehicle is temporarily stopped, and is different from parking. In this state, temperature information is acquired from the temperature sensor 102 in step S60, and in step S61, it is determined whether the temperature is equal to or higher than Tr. Although the temperature Tr used as the judgment criterion in step S61 has been described as being equal to the temperature Tr used as the judgment criterion in step S55, the temperature Tr used as the judgment criterion in step S61 may be higher than the temperature Tr used as the judgment criterion in step S55. Furthermore, the temperature Tr used as the judgment criterion in step S61 may be lower than the temperature Tr used as the judgment criterion in step S55.

[0218] If the temperature is equal to or higher than Tr (YES), in step S62, the power of battery 101b is transferred to battery 101a. However, this is premised on the fact that there is power remaining in battery 101b. For example, when the temperature is Tr=25° C., if it is possible to operate the drive motor 108 using only battery 101a, power can be transferred to battery 101a until the power of battery 101b becomes zero or close to zero.

[0219] If the temperature is below Tr (NO), the power of battery 101a is transferred to battery 101b in step S63. However, this is premised on the fact that there is power remaining in battery 101a. For example, if the temperature is −20° C. and the drive motor 108 can be driven by battery 101b alone, power can be transferred to battery 101b until the power of battery 101a becomes zero or close to zero.

[0220] After the power transfer, the electric vehicle 100 starts running in step S64, whereby the power of the batteries 101a and 101b can be maintained at an appropriate state according to the temperature, and deterioration of each battery can also be suppressed.

[0221] According to one aspect of the present invention, for two or more types of batteries, the output of one battery can be increased in accordance with the temperature of the other battery, and power from one battery can be transferred to the other battery in accordance with the temperature during periods when the vehicle is not in operation, thereby making it possible to adjust the SOC of each battery to an appropriate state in accordance with the temperature. For example, the one battery can be a room temperature battery, and the other battery can be a low temperature battery. Note that the one and the other are merely examples, and these can be interpreted differently depending on the temperature.

[0222] <Use Example 2> Next, a use example 2 of the battery control system or the like according to one embodiment of the present invention will be described with reference to FIGS. 13 and 14 .

[0223] First, as in Usage Example 1, in step S51 the charging stand plug is inserted into charging port 109. Then, unlike Usage Example 1, in step S71 temperature information is acquired from temperature sensor 102, and in step S72 it is determined whether the temperature is equal to or higher than Tm. Tm can be determined based on the battery characteristics of battery 101a and battery 101b; for example, if Tm=-10°C, it is determined in step S72 whether the temperature is equal to or higher than -10°C.

[0224] If the temperature is above Tm (YES), as in Usage Example 1, charging of batteries 101a and 101b begins in step S52, the plug is removed from charging port 109 in step S53, and electric vehicle 100 starts running in step S54.

[0225] If the temperature is below Tm (if NO), the heater 114 is operated, unlike in Use Example 1. Thereafter, the process returns to step S72, and it is determined whether the temperature is equal to or higher than Tm. That is, in Use Example 2, the temperature during charging of the batteries 101a and 101b is controlled to be equal to or higher than Tm.

[0226] The subsequent steps S54 to S59 are the same as those in Usage Example 1. The process proceeds from (Y) in Fig. 13 to (Y) in Fig. 14, and the subsequent steps S60 to S64 are the same as those in Usage Example 1.

[0227] When charging the battery, it is preferable to set the temperature to, for example, 0° C. or higher, since this allows for high charging characteristics.

[0228] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0229] Embodiment Mode 4 In this embodiment mode, a structure of a battery cell that can be applied to the above embodiment modes will be described. Unless otherwise specified, the battery cell shown in this embodiment mode can be applied to a room temperature battery or a low temperature battery.

[0230] Specifically, the positive electrode of the battery cell will be described with reference to FIGS. 15A and 15B.

[0231] [Positive Electrode] The battery cell has a positive electrode. Fig. 15A shows an example of a cross-sectional view of the positive electrode. The positive electrode has a positive electrode active material layer 571 on a positive electrode current collector 550. The positive electrode active material layer 571 includes a positive electrode active material 561, a positive electrode active material 562, a binder (binding agent) 555, a conductive additive 553, and an electrolyte solution 556.

[0232] [Positive Electrode Current Collector] The positive electrode has a positive electrode current collector 550. A highly conductive material can be used for the positive electrode current collector 550. Specifically, metals such as copper, gold, platinum, aluminum, iron, or titanium, and alloys of these metals, etc., can be used. Stainless steel can also be used as an iron alloy. A metal or alloy that does not dissolve at the potential of the positive electrode can be used for the positive electrode current collector 550. An aluminum alloy containing an element that improves heat resistance, such as silicon, titanium, neodymium, scandium, or molybdenum, can be used for the positive electrode current collector 550. A metal that reacts with silicon to form silicide, such as titanium, can be used for the positive electrode current collector 550. Metal elements that react with silicon to form silicide, such as titanium, can be used for the positive electrode current collector 550. In addition to titanium, other metal elements that react with silicon to form silicide include zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, and nickel.

[0233] The thickness of the positive electrode current collector 550 is preferably 5 μm to 30 μm, and more preferably 10 μm to 20 μm, and the positive electrode current collector 550 may be in the form of a sheet or plate. The positive electrode current collector 550 may be subjected to a punching process or an expanded metal process. The punching process is a stamping process, and the expanded metal process is a process in which slits are made and the positive electrode current collector 550 is stretched. The punching and expanded metal processes result in a mesh-like positive electrode current collector 550 having circular, elliptical, or diamond-shaped openings. Using a positive electrode current collector 550 having the openings can also produce a lightweight battery cell.

[0234] [Positive Electrode Active Material] The positive electrode includes a positive electrode active material. The positive electrode active material 561 and the positive electrode active material 562 shown in FIG. 15A are sometimes referred to as positive electrode active material particles, but the positive electrode active material may have a variety of shapes other than particulate. The positive electrode active material 561 and the positive electrode active material 562 may be either primary particles or secondary particles. In this specification, the term "primary particle" refers to the smallest unit particle (clump) that does not have a grain boundary when observed at 5000x magnification using a scanning electron microscope (SEM). In other words, the primary particle is the smallest unit particle. The term "secondary particle" refers to a particle (particle independent from other particles) formed by agglomeration of the primary particles so as to share a portion of the grain boundary (such as the outer periphery of the primary particle). In other words, the secondary particle has a grain boundary.

[0235] A material capable of inserting and desorbing carrier ions can be used for the positive electrode active material 561 and the positive electrode active material 562. The carrier ions can be lithium ions, sodium ions, potassium ions, calcium ions, strontium ions, barium ions, beryllium ions, or magnesium ions.

[0236] Materials capable of inserting and extracting lithium ions include lithium composite oxides having an olivine-type crystal structure, a layered rock salt-type crystal structure, or a spinel-type crystal structure.

[0237] For example, a lithium composite oxide having an olivine-type crystal structure is LiMPO ４ (where M=one or more of Fe, Mn, Ni, and Co). Since Fe and Mn have excellent thermal stability, using Fe or Mn as M, or using Fe and Mn as M, is suitable as a positive electrode active material. When Fe is used as M, LiFePO ４ This is sometimes referred to as LFP. LFP is sometimes referred to as a composite oxide containing lithium, iron, and phosphorus, and may contain elements other than the exemplified elements, and may further contain elements that do not contribute to capacity.

[0238] For example, a lithium composite oxide having a layered rock salt crystal structure is LiMO ２(where M=one or more of Fe, Mn, Ni, and Co). When Co is used as M, LiCoO ２ This is sometimes referred to as LCO or lithium cobalt oxide. LCO is sometimes referred to as a composite oxide containing lithium and cobalt, and may contain elements other than the exemplified elements, as well as elements that do not contribute to capacity.

[0239] Lithium cobalt oxide may contain one or more elements selected from the group consisting of nickel, chromium, aluminum, iron, magnesium, molybdenum, zinc, zirconium, indium, gallium, copper, titanium, niobium, silicon, fluorine, and phosphorus. These elements may be referred to as "additive elements." The additive elements are often located in the surface layer of the active material, and the "surface layer" refers to a region up to 50 nm deep, preferably up to 30 nm deep, and more preferably up to 10 nm deep from the surface of the active material.

[0240] Furthermore, as a lithium composite oxide having a layered rock salt type crystal structure, LiNi ｘ Co ｙ Mn ｚ O ２ There is a NiCoMn system represented by (x>0, y>0, 0.8<x+y+z<1.2). ｘ Co ｙ Mn ｚ O ２ (x>0, y>0, 0.8<x+y+z<1.2) is sometimes written as NCM. ｘ Co ｙ Mn ｚ O ２In the above formula, it is preferable that, for example, 0.1x<y<8x and 0.1x<z<8x are satisfied. As a specific example, it is preferable that x, y, and z satisfy x:y:z=1:1:1 or a value thereabout. As another specific example, it is preferable that x, y, and z satisfy x:y:z=5:2:3 or a value thereabout. As another specific example, it is preferable that x, y, and z satisfy x:y:z=8:1:1 or a value thereabout. As another specific example, it is preferable that x, y, and z satisfy x:y:z=9:0.5:0.5 or a value thereabout. As another specific example, it is preferable that x, y, and z satisfy x:y:z=6:2:2 or a value thereabout. As another specific example, it is preferable that x, y, and z satisfy x:y:z=1:4:1 or a value thereabout. NCM may be referred to as a lithium composite oxide having Ni, Co, and Mn, or as a composite oxide having Li, Ni, Co, and Mn.

[0241] The NCM may also contain one or more elements selected from calcium, boron, gallium, aluminum, boron, and indium at a concentration of 0.1 aT% to 3 aT%. Calcium, boron, gallium, aluminum, boron, and indium at the above concentrations may be referred to as "additive elements." The additive elements are often located in the surface layer of the active material, and the surface layer refers to a region up to 50 nm deep, preferably up to 30 nm deep, and more preferably up to 10 nm deep from the surface of the active material.

[0242] Furthermore, a NiCoMn-based lithium composite oxide containing aluminum as a main component may be referred to as NCMA, which may be referred to as a lithium composite oxide containing Ni, Co, Mn, and Al, or as a composite oxide containing Li, Ni, Co, Mn, and Al.

[0243] Furthermore, a lithium composite oxide containing Ni and Co as a main component and containing aluminum may be referred to as an NCA. An NCA may be referred to as a lithium composite oxide containing Ni, Co, and Al, or as a composite oxide containing Li, Ni, Co, and Al.

[0244] For example, the spinel-type crystalline lithium composite oxide is lithium manganese spinel (LiMn ２ O ４ ) etc.

[0245] In addition, NaFeO is a material that can insert and extract sodium ions. ２ , NaNiO ２ , NaCoO ２ , NaMnO ２ , NaVO ２ , Na(Ni Ｘ Mn １−Ｘ ) O ２ (0<X<1), Na(Fe Ｘ Mn １−Ｘ ) O ２ (0<X<1), NaVPO ４ F, Na ２ FePO ４ F, Na ３ V ２ (P.O. ４ ) ３ The following can be mentioned:

[0246] Furthermore, V ２ O ５ , Nb ２ O ５ These oxides are being studied as positive electrode active materials.

[0247] The average particle size of the positive electrode active material 561 is 1 μm or more and 50 μm or less, preferably 5 μm or more and 30 μm or less. Here, the average particle size can be, for example, the median diameter (D50). In the case of a lithium composite oxide represented by NCM, the positive electrode active material 561 may exist as secondary particles. It is preferable that the secondary particles also satisfy the above average particle size. Secondary particles are considered to be agglomerations of primary particles, and when considered as agglomerations of primary particles satisfying the above average particle size, the size of the secondary particles should satisfy 10 μm or more and 100 μm or less, preferably 20 μm or more and 80 μm or less.

[0248] In order to increase the packing density of the active material, a positive electrode active material 562 having a different particle size may be further added. Different particle sizes refer to different maximum values ​​of average particle diameters or different median diameters (D50). The particle size of the positive electrode active material 562 is preferably 1 / 6 to 1 / 10 of the particle size of the positive electrode active material 561.

[0249] The charge density can be increased even without the positive electrode active material 562, and when the positive electrode active material 562 is not included, the number of manufacturing steps can be reduced, leading to further cost reduction.

[0250] The active material of the positive electrode active material 561 may be the same as or different from the active material of the positive electrode active material 562. The same active material includes the same main raw material of the active material, and may differ in the presence or absence of an additive element, etc. The different active material includes the active material including different main raw materials of the active material.

[0251] The positive electrode active material 561 and the positive electrode active material 562 may contain an additive element, and the additive element may be located in the surface layer portion. The additive element may be unevenly distributed in the surface layer portion. "Uneven distribution" means that the additive element is present unevenly or unevenly, and includes a state in which the concentration of the additive element is higher in the surface layer portion. "Uneven distribution" may also be referred to as "segregation" or "precipitation."

[0252] 15A shows a surface layer portion 572 of positive electrode active material 561. In a cross-sectional view, surface layer portion 572 exists within 50 nm, more preferably within 35 nm, even more preferably within 20 nm, and most preferably within 10 nm from the surface of positive electrode active material 561 toward the inside. Although not shown, positive electrode active material 562 may have a surface layer portion similar to surface layer portion 572.

[0253] The structure of the active material having the surface layer portion 572 may be referred to as a core-shell structure.

[0254] Although the positive electrode active material 561 is shown as particulate in FIG. 15A , it is not limited to being particulate. As shown in FIG. 15B , the cross-sectional shape of the positive electrode active material 561 may be elliptical, rectangular, trapezoidal, conical, square with rounded corners, or asymmetrical. Note that the particulate positive electrode active material may be deformed into the shape shown in FIG. 15B by pressing in the positive electrode fabrication process. The other configurations in FIG. 15B are the same as those in FIG. 15A , and therefore will not be described again.

[0255] 15A , the positive electrode has a binder 555. The binder 555 is provided to prevent the positive electrode active material 561, the positive electrode active material 562, or the conductive additive 553 from sliding off the positive electrode current collector 550. The binder 555 also plays a role in binding the positive electrode active material 561 and the conductive additive 553 together. Similarly, the binder 555 also plays a role in binding the positive electrode active material 562 and the conductive additive 553 together. Therefore, the binder 555 may be positioned so as to be in contact with the positive electrode current collector 550, between the positive electrode active material 561 and the conductive additive 553, between the positive electrode active material 562 and the conductive additive 553, or so as to be entangled with the conductive additive 553.

[0256] It is preferable to use a rubber material such as styrene-butadiene rubber (SBR), styrene-isoprene-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, or ethylene-propylene-diene copolymer as the binder 555. Fluorine rubber can also be used as the binder.

[0257] Furthermore, it is preferable to use, for example, a water-soluble polymer as the binder 555. Examples of the water-soluble polymer that can be used include polysaccharides. Examples of the polysaccharide that can be used include cellulose derivatives such as carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, and regenerated cellulose, as well as starch. It is even more preferable to use these water-soluble polymers in combination with the above-mentioned rubber material.

[0258] Furthermore, as the binder 555, it is preferable to use a material such as polystyrene, polymethyl acrylate, polymethyl methacrylate (polymethyl methacrylate, PMMA), sodium polyacrylate, polyvinyl alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide, polyimide, polyvinyl chloride, polytetrafluoroethylene, polyethylene, polypropylene, polyisobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), ethylene propylene diene polymer, polyvinyl acetate, or nitrocellulose.

[0259] The binder 555 may be a combination of two or more of the above.

[0260] For example, the binder 555 may be a combination of a material with particularly excellent viscosity adjustment properties and another material. For example, while rubber materials have excellent adhesive strength and elasticity, it may be difficult to adjust the viscosity when mixed with a solvent. In such cases, it is preferable to mix the binder 555 with a material with particularly excellent viscosity adjustment properties. Examples of materials with particularly excellent viscosity adjustment properties include water-soluble polymers. Examples of water-soluble polymers with particularly excellent viscosity adjustment properties include the aforementioned polysaccharides, such as carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, and diacetyl cellulose, cellulose derivatives such as regenerated cellulose, and starch.

[0261] In addition, the solubility of cellulose derivatives such as carboxymethyl cellulose can be increased by converting them into salts such as sodium or ammonium salts of carboxymethyl cellulose, making them more effective as viscosity adjusters. Higher solubility can also improve dispersibility with active materials or other components when preparing electrode slurry. In this specification, cellulose and cellulose derivatives used as electrode binders also include their salts.

[0262] Water-soluble polymers stabilize viscosity by dissolving in water, allowing active materials and other materials combined as binders, such as styrene-butadiene rubber, to be stably dispersed in aqueous solutions. Furthermore, the presence of functional groups is expected to facilitate stable adsorption to the surface of active materials. Furthermore, many cellulose derivatives, such as carboxymethyl cellulose, contain functional groups such as hydroxyl or carboxyl groups, and the presence of these functional groups is expected to facilitate interactions between polymers, resulting in widespread coverage of the active material surface.

[0263] When the binder covers the surface of the active material or contacts the surface and forms a film, it is expected to function as a passive film and have the effect of suppressing decomposition of the electrolyte. Here, the "passive film" refers to a film with no electrical conductivity or a film with extremely low electrical conductivity. For example, when a passive film is formed on the surface of the active material, it can suppress decomposition of the electrolyte at the battery reaction potential. Furthermore, it is more desirable that the passive film suppresses electrical conductivity while still allowing lithium ions to conduct.

[0264] [Conductive additive] The positive electrode active material 561 is a composite oxide and therefore may have high resistance, making it difficult to collect current from the positive electrode active material 561 to the positive electrode current collector 550. In this case, as shown in Fig. 15A , the positive electrode has conductive additives 553 and 554, which function to assist the current path between the positive electrode active material 561 and the positive electrode current collector 550, the current path between the plurality of positive electrode active materials 561, the current path between the plurality of positive electrode active materials and the positive electrode current collector 550, and the like.

[0265] To fulfill such a function, the conductive additives 553 and 554 preferably have a material with lower resistance than the positive electrode active material 561. Furthermore, the conductive additives 553 and 554 may be positioned so as to be in contact with the positive electrode current collector 550, or may be positioned in the gaps in the positive electrode active material 561. The conductive additives are also called conductivity-imparting agents or conductive materials based on their roles.

[0266] Note that the positive electrode may have either the conductive additive 553 or the conductive additive 554 .

[0267] The conductive additive is typically a carbon material or a metal material. The conductive additive 553 is particulate, and examples of such particulate conductive additives include carbon black (furnace black, acetylene black, graphite, etc.). Many carbon blacks have a smaller particle size than the positive electrode active material 561. The conductive additive 554 is fibrous, and examples of such fibrous conductive additives include carbon nanotubes (CNT) and VGCF (registered trademark). Some conductive additives are sheet-shaped, and an example of a sheet-shaped conductive additive is multilayer graphene. Sheet-shaped conductive additives may appear thread-like in the cross section of the positive electrode.

[0268] The particulate conductive additive 553 can penetrate into the gaps between the positive electrode active materials 561 and is prone to agglomeration. Therefore, the particulate conductive additive 553 can assist the conductive path between the positive electrode active materials arranged nearby. The fibrous conductive additive 554 has a bent region, but is larger than the positive electrode active material 561. Therefore, the fibrous conductive additive 554 can assist the conductive path between the positive electrode active materials arranged apart or spaced apart, in addition to between the adjacent positive electrode active materials. In this way, it is preferable to mix two or more shapes of conductive additives.

[0269] For example, a sheet-like conductive additive may be used instead of the fibrous conductive additive 554. When multilayer graphene is used as the sheet-like conductive additive and carbon black is used as the particulate conductive additive, the weight of the carbon black in a mixed slurry state may be 1.5 to 20 times, preferably 2 to 9.5 times, that of the graphene.

[0270] When the mixing ratio of multilayer graphene to carbon black is within the above range, the carbon black does not aggregate and is easily dispersed. Furthermore, when the mixing ratio of multilayer graphene to carbon black is within the above range, the electrode density can be made higher than when only carbon black is used as the conductive additive. By increasing the electrode density, the capacity per unit weight can be increased.

[0271] Furthermore, by setting the mixing ratio of multilayer graphene and carbon black within the above range, rapid charging can be achieved.

[0272] [Electrolyte] The battery cell contains an electrolyte. The electrolyte described in this embodiment preferably uses an organic solvent as a solvent, and an electrolyte (lithium salt) is dissolved in the organic solvent. However, the organic solvent is not limited to an organic solvent that is liquid at room temperature; a solid electrolyte that is solid at room temperature can also be used. Alternatively, an electrolyte containing both an organic solvent that is liquid at room temperature and a solid electrolyte that is solid at room temperature (based on the state, this is called a semi-solid electrolyte) can also be used. For example, the positive electrode in FIG. 15A shows an electrolyte 556. Although not shown in FIG. 15A, the negative electrode (described later) also contains the electrolyte 556.

[0273] <Examples of organic solvents for room temperature> Examples of organic solvents for room temperature are described below.

[0274] The room temperature organic solvent is preferably an aprotic organic solvent, and examples thereof include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, chloroethylene carbonate, vinylene carbonate, γ-butyrolactone, γ-valerolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfoxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran, sulfolane, and sultone, and any combination and ratio (sometimes referred to as a ratio and expressed by volume) of two or more of these can be used.

[0275] The room-temperature organic solvent can be one or more flame-retardant and non-volatile ionic liquids (room-temperature molten salts). The use of an ionic liquid can prevent battery cell expansion, rupture, and fire even when the internal temperature rises due to an internal short circuit or overcharging. The ionic liquid is composed of a cation and an anion, and includes an organic cation and an anion. Examples of the organic cation include aliphatic onium cations such as quaternary ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations, and aromatic cations such as imidazolium cations and pyridinium cations. Examples of anions used in the ionic liquid include monovalent amide anions, monovalent methide anions, fluorosulfonate anions, perfluoroalkylsulfonate anions, tetrafluoroborate anions, perfluoroalkylborate anions, hexafluorophosphate anions, and perfluoroalkylphosphate anions.

[0276] The lithium salt dissolved in the room temperature organic solvent is, for example, LiPF ６ , LiClO ４ , LiAsF ６ , LiBF ４ , LiAlCl ４ , LiSCN, LiBr, LiI, Li ２ SO ４ , Li ２ B １０ Cl １０ , Li ２ B １２ Cl １２ , LiCF ３ SO ３ , LiC ４ F ９ SO ３ , LiC(CF ３ SO ２ ) ３ , LiC(C ２ F ５ SO ２ ) ３ , LiN(CF ３ SO ２ ) ２ , LiN(C ４ F ９ SO ２ ) (CF３ SO ２ ), and LiN(C ２ F ５ SO ２ ) ２ One or more selected from the above can be used.

[0277] The room-temperature organic solvent may also contain an additive. For example, additives such as vinylene carbonate (VC), propane sultone (PS), tert-butylbenzene (TBB), fluoroethylene carbonate (FEC), lithium bis(oxalate)borate (LiBOB), or dinitrile compounds such as succinonitrile and adiponitrile may be added to the organic solvent or ionic liquid. The concentration of the additive may be, for example, 0.1 wt % to 5 wt % of the total electrolyte solution. VC or LiBOB is particularly preferred because it easily forms a good coating on the active material, etc.

[0278] A polymer gel electrolyte may be used as the room temperature organic solvent. The use of a polymer gel electrolyte increases safety against leakage and the like. It also allows for thinner and lighter battery cells.

[0279] Examples of polymers that can be used to form gels include silicone gel, acrylic gel, acrylonitrile gel, polyethylene oxide gel, polypropylene oxide gel, and fluorine-based polymer gel.

[0280] Examples of polymers that can be used include polymers having a polyalkylene oxide structure such as polyethylene oxide (PEO), PVDF, polyacrylonitrile, and copolymers containing these. For example, PVDF-HFP, which is a copolymer of PVDF and hexafluoropropylene (HFP), can be used. The polymer formed may also have a porous shape.

[0281] Room-temperature batteries can use solid electrolytes containing inorganic materials. For example, sulfide-based solid electrolytes, oxide-based solid electrolytes, halide-based solid electrolytes, etc. can be used. Solid electrolytes containing polymeric materials such as PEO (polyethylene oxide) can also be used. When using solid electrolytes, separators and spacers are not required. Furthermore, because the battery cells can be solidified, the risk of leakage is eliminated, dramatically improving safety.

[0282] The sulfide-based solid electrolytes include thiolithium-based (Li １０ GeP ２ S １２ , Li ３．２５ Ge ０．２５ P ０．７５ S ４ etc.), sulfide glass (70Li ２ S・30P ２ S530Li ２ S・26B ２ S ３ ・44LiI, 63Li ２ S・36SiS ２ ・1Li ３ P.O. ４ , 57Li ２ S・38SiS ２ ・5Li ４ SiO ４ , 50Li ２ S・50GeS ２ etc.), sulfide crystallized glass (Li ７ P ３ S １１ , Li ３．２５ P ０．９５ S ４ Sulfide-based solid electrolytes have the advantages of being highly conductive, being able to be synthesized at low temperatures, and being relatively soft, which makes it easy to maintain conductive paths even after charging and discharging.

[0283] The oxide-based solid electrolyte includes a material having a perovskite crystal structure (La ２／３−ｘ Li ３ｘ TiO ３ etc.), materials having a NASICON type crystal structure (Li １＋Ｘ Al Ｘ Ti ２−Ｘ (P.O.４ ) ３ etc.), materials having a garnet-type crystal structure (Li ７ La ３ Zr ２ O １２ etc.), materials having a LISICON type crystal structure (Li １４ ZnGe ４ O １６ etc.), LLZO (Li ７ La ３ Zr ２ O １２ ), oxide glass (Li ３ P.O. ４ -Li ４ SiO ４ , 50Li ４ SiO ４ ・50Li ３ BO ３ etc.), oxide crystallized glass (Li １．０７ Al ０．６９ Ti １．４６ (P.O. ４ ) ３ , Li １．５ Al ０．５ Ge １．５ (P.O. ４ ) ３ Oxide-based solid electrolytes have the advantage of being stable in the atmosphere.

[0284] Halide-based solid electrolytes include LiAlCl ４ , Li ３ InBr ６ , LiF, LiCl, LiBr, LiI, etc. Furthermore, composite materials in which these halide-based solid electrolytes are filled into the pores of porous aluminum oxide or porous silica can also be used as the solid electrolyte.

[0285] Also, different solid electrolytes may be mixed and used.

[0286] Among them, Li having a NASICON type crystal structure １＋ｘ Al ｘ Ti ２−ｘ (P.O. ４ ) ３Since (0[x[1) (hereinafter referred to as LATP) contains the same elements as the main raw materials or additive elements of the positive electrode active material used in one embodiment of the present invention, i.e., aluminum and titanium, a synergistic effect can be expected in improving cycle characteristics, which is preferable. In addition, an improvement in productivity due to a reduction in the number of steps can also be expected. In this specification and the like, the NASICON-type crystal structure refers to M ２ (A.O. ４ ) ３ (M: transition metal, A: S, P, As, Mo, W, etc.), ６ Octahedron and AO ４ It refers to a structure in which tetrahedrons are arranged three-dimensionally with their vertices shared.

[0287] <Examples of organic solvents for low temperatures> Examples of organic solvents for low temperatures are described below.

[0288] The low-temperature organic solvent may contain ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC), and the volume ratio of the ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate may be x:y:100-x-y (where 5≦x≦35 and 0<y<65) when the total content of the ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate is 100 vol%. More specifically, an organic solvent containing EC, EMC, and DMC in a volume ratio of EC:EMC:DMC=30:35:35 may be used. Note that the above volume ratio may be the volume ratio before mixing with the electrolytic solution, and the outside air temperature when mixing the electrolytic solution may be room temperature (typically, 25°C).

[0289] EC is a cyclic carbonate with a high dielectric constant, which promotes the dissociation of lithium salts. However, EC has a high viscosity and a high freezing point (melting point) of 38°C, making it difficult to use EC alone as an organic solvent in low-temperature environments. Therefore, the organic solvent specifically described as one aspect of the present invention further includes EMC and DMC, rather than EC alone. EMC is a chain carbonate that reduces the viscosity of the electrolyte and has a freezing point of -54°C. DMC is also a chain carbonate that reduces the viscosity of the electrolyte and has a freezing point of -43°C. Electrolyte c, which is prepared using an organic solvent in which EC, EMC, and DMC having such physical properties are mixed in a volume ratio of x:y:100-x-y (where 5≦x≦35 and 0<y<65) at 25°C, assuming a total content of these three organic solvents as 100 vol%, is characterized by a freezing point of -40°C or lower.

[0290] A typical electrolytic solution used in battery cells freezes at around −20° C., making it difficult to fabricate a battery that can be charged and discharged at −40° C. The electrolyte described above as a low-temperature organic solvent has a freezing point of −40° C. or lower, making it possible to realize a battery cell that can be charged and discharged even in an extremely low-temperature environment of −40° C.

[0291] The lithium salt to be dissolved in the organic solvent for low temperature can be selected from those described as the lithium salt for the organic solvent for normal temperature.

[0292] The additives contained in the organic solvent for low temperature use can be selected from those described as additives for the organic solvent for normal temperature use.

[0293] [Negative Electrode] The battery cell has a negative electrode. The negative electrode has a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer has a negative electrode active material, and may further have a conductive additive and a binder.

[0294] [Negative Electrode Current Collector] The negative electrode has a negative electrode current collector, which may be made of the same material as the positive electrode current collector.

[0295] [Negative Electrode Active Material] The negative electrode contains a negative electrode active material, which may be, for example, an alloy material or a carbon material.

[0296] In addition, the negative electrode active material can be an element capable of undergoing a charge-discharge reaction through alloying and dealloying reactions with lithium. For example, a material containing at least one of silicon, tin, gallium, aluminum, germanium, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc. can be used. These elements have a larger capacity than carbon, and silicon in particular has a high theoretical capacity of 4200 mAh / g. For this reason, it is preferable to use silicon as the negative electrode active material. Alternatively, compounds containing these elements may be used. For example, SiO, Mg ２ Si, Mg ２ Ge, SnO, SnO ２ , Mg ２ Sn, SnS ２ , V ２ Sn ３ , FeSn ２ , CoSn ２ , Ni ３ Sn ２ , Cu ６ Sn ５ , Ag ３ Sn, Ag ３ Sb, Ni ２ MnSb, CeSb ３ , LaSn ３ , La ３ Co ２ Sn ７ , CoSb ３ , InSb, SbSn, etc. Here, elements capable of undergoing charge-discharge reactions by alloying / dealloying reactions with lithium, and compounds containing such elements, are sometimes referred to as alloy materials.

[0297] In this specification, "SiO" refers to, for example, silicon monoxide. ｘ Here, x preferably has a value of 1 or close to 1. For example, x is preferably 0.2 or more and 1.5 or less, and more preferably 0.3 or more and 1.2 or less.

[0298] The carbon material may be graphite, easily graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), carbon fiber (carbon nanotube), graphene, carbon black, or the like.

[0299] Examples of graphite include artificial graphite and natural graphite. Examples of artificial graphite include mesocarbon microbeads (MCMB), coke-based artificial graphite, and pitch-based artificial graphite. Here, spherical graphite having a spherical shape can be used as the artificial graphite. For example, MCMB may have a spherical shape and is therefore preferred. Furthermore, it is relatively easy to reduce the surface area of ​​MCMB, and this may be preferred. Examples of natural graphite include flake graphite and spherical natural graphite.

[0300] When lithium ions are inserted into graphite (when a lithium-graphite intercalation compound is formed), graphite exhibits a potential as low as that of metallic lithium (0.05 V to 0.3 V vs. Li / Li ＋ This allows lithium-ion batteries using graphite to exhibit high operating voltages. Graphite is also preferred because it has advantages such as a relatively high capacity per unit volume, relatively small volume expansion, low cost, and greater safety compared to lithium metal.

[0301] Titanium dioxide (TiO ２ ), lithium titanium oxide (Li ４ Ti ５ O １２ ), lithium-graphite intercalation compound (Li ｘ C ６ ), niobium pentoxide (Nb ２ O ５ ), tungsten dioxide (WO ２ ), molybdenum dioxide (MoO ２ ) and other oxides can be used.

[0302] In addition, as the negative electrode active material, a nitride of lithium and a transition metal, Li ３ Li with N-type structure ３−ｘ M ｘ N (M=Co, Ni, Cu) can be used. For example, Li ２．６ Co ０．４ N has a large discharge capacity (900 mAh / g, 1890 mAh / cm ３ ) and is preferred.

[0303] When a nitride of lithium and a transition metal is used, lithium ions are contained in the negative electrode active material, so that the above V, which does not contain lithium ions, is used as the positive electrode active material. ２ O ５ , Cr ３ O ８ It is preferable that the material can be combined with a material such as the above. Even when a material containing lithium ions is used as the positive electrode active material, it is possible to use a nitride of lithium and a transition metal as the negative electrode active material by first desorbing the lithium ions contained in the positive electrode active material.

[0304] Furthermore, a material that undergoes a conversion reaction can also be used as the negative electrode active material. For example, a transition metal oxide that does not form an alloy with lithium, such as cobalt oxide (CoO), nickel oxide (NiO), or iron oxide (FeO), can be used as the negative electrode active material. Further examples of materials that undergo a conversion reaction include Fe ２ O ３ ,CuO,Cu ２ O, RuO ２ , Cr ２ O ３ oxides such as CoS ０．８９ , sulfides such as NiS and CuS, Zn ３ N ２ , Cu ３ N, Ge ３ N ４ Nitrides such as NiP ２ , FeP ２ , CoP ３ Phosphides such as FeF ３ , BiF ３ This also occurs with fluorides such as

[0305] The conductive material and binder that can be contained in the negative electrode active material layer can be the same as the conductive material and binder that can be contained in the positive electrode active material layer.

[0306] As another embodiment of the negative electrode of the present invention, a negative electrode having no negative electrode active material can be used. In a battery cell using a negative electrode having no negative electrode active material, lithium is deposited on the negative electrode current collector during charging, and the lithium on the negative electrode current collector can be dissolved during discharging. Therefore, in a state other than a fully discharged state, lithium is present on the negative electrode current collector.

[0307] When a negative electrode having no negative electrode active material is used, a film for uniformly depositing lithium may be provided on the negative electrode current collector. For example, a solid electrolyte having lithium ion conductivity can be used as the film for uniformly depositing lithium. Examples of solid electrolytes that can be used include sulfide-based solid electrolytes, oxide-based solid electrolytes, and polymer-based solid electrolytes. Among these, polymer-based solid electrolytes are suitable as a film for uniformly depositing lithium because it is relatively easy to form a uniform film on the negative electrode current collector.

[0308] Furthermore, when a negative electrode that does not have a negative electrode active material is used, a negative electrode current collector having projections and recesses can be used. When a negative electrode current collector having projections and recesses is used, the recesses of the negative electrode current collector become cavities into which lithium contained in the negative electrode current collector can be easily deposited, and therefore, when lithium is deposited, it is possible to prevent it from forming a dendritic shape.

[0309] [Conductive additive] The negative electrode contains a conductive additive. The conductive additive contained in the positive electrode can be used as the conductive additive contained in the negative electrode.

[0310] [Separator] A battery cell has a separator placed between the positive electrode and the negative electrode. The separator provides insulation between the positive electrode and the negative electrode. The separator is preferably made of a stable material that has excellent electrolyte retention properties. Examples of separators that can be used include those made of cellulose-containing fibers such as paper, nonwoven fabrics, glass fibers, ceramics, or synthetic fibers made of nylon (polyamide), vinylon (polyvinyl alcohol-based fibers), polyester, polyimide, acrylic, polyolefin, or polyurethane.

[0311] The separator preferably has a porosity of 30% to 85%, preferably 45% to 65%. A high porosity is preferable because it facilitates impregnation with the electrolyte. The porosity of the separator may be different between the positive electrode side and the negative electrode side, and it is preferable that the porosity on the positive electrode side is higher than the porosity on the negative electrode side. To achieve different porosities, the same material may be used with different porosities, or different materials with different porosities may be used. When different materials are used, the porosity of the separator can be made different by stacking them.

[0312] The separator preferably has an average pore diameter of 40 nm to 3 μm, preferably 70 nm to 1 μm. A larger average pore diameter is preferable because it facilitates carrier ion transport. The average pore diameter of the separator may be different between the positive electrode side and the negative electrode side, and it is preferable that the average pore diameter on the positive electrode side is larger than the average pore diameter on the negative electrode side. To make the average pore diameters different, there are configurations in which the average pore diameters are made different for the same material, or configurations in which different materials with different average pore diameters are used. When different materials are used, the average pore diameters of the separator can be made different by stacking them.

[0313] The thickness of the separator is preferably 5 μm or more and 200 μm or less, and more preferably 5 μm or more and 100 μm or less.

[0314] The separator preferably has a heat resistance of 200° C. or higher.

[0315] It is preferable to use a separator made of polyimide, having a thickness of 10 μm or more and 50 μm or less and a porosity of 75% or more and 85% or less, because this improves the output characteristics of the battery cell.

[0316] The separator may be processed into a bag shape, and the bag-shaped separator may be disposed so as to wrap or sandwich either the positive electrode or the negative electrode.

[0317] When the separator has a multilayer structure, an organic material film such as polypropylene or polyethylene coated with a ceramic material, a fluorine-based material, a polyamide-based material, or a mixture thereof can be used. Examples of ceramic materials include aluminum oxide particles or silicon oxide particles. Examples of fluorine-based materials include PVDF or polytetrafluoroethylene. Examples of polyamide-based materials include nylon or aramid (meta-aramid, para-aramid).

[0318] Coating the separator surface with a ceramic material improves oxidation resistance, suppressing separator degradation during high-voltage charging and discharging and improving battery cell reliability. Coating the separator surface with a fluorine-based material also improves adhesion between the separator and electrodes, improving output characteristics. Coating the separator surface with a polyamide-based material, especially aramid, improves heat resistance, improving battery cell safety.

[0319] For example, both sides of a polypropylene film may be coated with a mixed material of aluminum oxide and aramid, or the surface of the polypropylene film that contacts the positive electrode may be coated with a mixed material of aluminum oxide and aramid, and the surface that contacts the negative electrode may be coated with a fluorine-based material.

[0320] The use of such a multilayer separator allows the functions of each material to be imparted to the separator, so that even if the separator as a whole is thin, insulation between the positive and negative electrodes can be ensured and the safety of the battery cell can be maintained, which is preferable because it allows the capacity per volume of the battery cell to be increased.

[0321] [Exterior Body] The battery cell has an exterior body. For example, a metal material such as aluminum or a resin material can be used as the exterior body. A film-like exterior body can also be used. For example, a three-layer film can be used, in which a thin, flexible metal film such as aluminum, stainless steel, copper, or nickel is provided on a film made of a material such as polyethylene, polypropylene, polycarbonate, ionomer, or polyamide, and an insulating synthetic resin film such as a polyamide resin or polyester resin is further provided on the thin metal film as the outer surface of the exterior body.

[0322] As described above, in this embodiment, examples of the configuration of the battery cell that can be applied to the above embodiment have been given, but the present invention is not limited to the above examples.

[0323] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0324] Fifth Embodiment In the present embodiment, a method for manufacturing a positive electrode active material 1 that can be applied to the above-described embodiments will be described. Unless otherwise specified, the method for manufacturing a positive electrode active material 1 shown in the present embodiment can be applied to a room temperature battery or a low temperature battery.

[0325] Specifically, a method for producing a positive electrode active material by coprecipitation will be described with reference to FIG. 16 and other figures.

[0326] [Method for producing positive electrode active material 1] <Transition metal M source> A transition metal M source 81 (referred to as M source in the drawing) shown in Fig. 16 will be described. As the transition metal M, for example, at least one of nickel, cobalt, and manganese can be used. For example, as the transition metal M, there are cases where only nickel is used, cases where two types of metals, cobalt and manganese, nickel and cobalt, or three types of metals, nickel, cobalt, and manganese, are used.

[0327] When nickel, cobalt, and manganese are used, it is preferable to set the mixing ratio of nickel, cobalt, and manganese within a range that allows a layered rock salt type crystal structure to be formed.

[0328] In particular, containing a large amount of nickel as the transition metal M is preferable because the raw material may be cheaper than when it contains a large amount of cobalt, and the charge / discharge capacity per weight may be increased. Such an active material is suitable for electric vehicles. For example, the nickel content of the transition metal M is preferably more than 25 atomic %, more preferably 60 atomic % or more, and even more preferably 80 atomic % or more. However, if the proportion of nickel is too high, chemical stability and heat resistance may be reduced. Therefore, it is preferable that the nickel content of the transition metal M is 95 atomic % or less.

[0329] The presence of cobalt as the transition metal M is preferable because it results in a high average discharge voltage and can provide a highly reliable battery cell because the cobalt contributes to stabilizing the layered rock-salt structure. Such an active material is suitable for electric vehicles.

[0330] However, since cobalt is more expensive than nickel and manganese and is unstable, if the proportion of cobalt is too high, the production cost may increase. Therefore, for example, the cobalt content of the transition metal M is preferably 2.5 atomic % or more and 34 atomic % or less. Note that the transition metal M does not necessarily have to contain cobalt.

[0331] The active material preferably contains manganese as the transition metal M, because it improves heat resistance and chemical stability, making it suitable for electric vehicles.

[0332] However, if the proportion of manganese is too high, the discharge voltage and discharge capacity tend to decrease. Therefore, for example, it is preferable that manganese is contained in the transition metal M in an amount of 2.5 atomic % or more and 34 atomic % or less. Note that the transition metal M does not necessarily have to contain manganese.

[0333] The transition metal M source 81 may be prepared as an aqueous solution containing the transition metal M. As the nickel source, an aqueous solution of a nickel salt, such as nickel sulfate, nickel chloride, or nickel nitrate, or a hydrate thereof, may be used. Alternatively, an aqueous solution of an organic acid salt of nickel, such as nickel acetate, or a hydrate thereof may be used. Alternatively, an aqueous solution of a nickel alkoxide or an organic nickel complex may be used. In this specification and the like, an organic acid salt refers to a compound of a metal with an organic acid, such as acetic acid, citric acid, oxalic acid, formic acid, or butyric acid.

[0334] The cobalt source can be a cobalt salt, such as cobalt sulfate, cobalt chloride, or cobalt nitrate, or an aqueous solution of a hydrate thereof. It can also be an aqueous solution of an organic cobalt salt, such as cobalt acetate, or a hydrate thereof. It can also be an aqueous solution of a cobalt alkoxide or an organic cobalt complex.

[0335] The manganese source can be a manganese salt such as manganese sulfate, manganese chloride, manganese nitrate, or an aqueous solution of a hydrate thereof. It can also be an aqueous solution of an organic acid salt of manganese, such as manganese acetate, or a hydrate thereof. It can also be an aqueous solution of a manganese alkoxide or an organic manganese complex.

[0336] In this embodiment, an aqueous solution of nickel sulfate, cobalt sulfate, and manganese sulfate dissolved in pure water is prepared as the transition metal M source 81. At this time, the nickel, cobalt, and manganese sulfate are weighed out so that the atomic ratio of nickel, cobalt, and manganese is Ni:Co:Mn=8:1:1 or approximately this ratio.

[0337] <Additive Element Source> Although not shown, an additive element source may be prepared in addition to the transition metal M source 81. The additive element added to the transition metal M source 81 is referred to as a first additive element. Specifically, the first additive element may include one or more elements selected from the group consisting of gallium, aluminum, boron, and indium.

[0338] When the first additive element is gallium, it can be referred to as a gallium source. As the gallium source, a compound containing gallium can be used. As the gallium-containing compound, for example, gallium sulfate, gallium chloride, or gallium nitrate, or a hydrate thereof can be used. Furthermore, as the gallium-containing compound, a gallium alkoxide or an organic gallium complex can be used. Furthermore, as the gallium-containing compound, an organic acid of gallium, such as gallium acetate, or a hydrate thereof can be used.

[0339] When the first added element is aluminum, it can be referred to as an aluminum source. An aluminum-containing compound can be used as the aluminum source. Examples of the aluminum-containing compound include aluminum sulfate, aluminum chloride, and aluminum nitrate, as well as hydrates thereof. Aluminum alkoxides or organic aluminum complexes may also be used as aluminum-containing compounds. Organic aluminum acids, such as aluminum acetate, or hydrates thereof may also be used as aluminum-containing compounds.

[0340] When the first additive element is boron, it can be referred to as a boron source. As the boron source, a compound containing boron can be used. The compound containing boron can be, for example, boric acid or a borate.

[0341] When the first additive element is indium, it can be referred to as an indium source. A compound containing indium can be used as the indium source. Examples of the indium-containing compound include indium sulfate, indium chloride, and indium nitrate, as well as hydrates thereof. Indium alkoxides or organic indium complexes may also be used as the indium-containing compound. Furthermore, organic acids of indium, such as indium acetate, or hydrates thereof may also be used as the indium-containing compound.

[0342] When a solution is used as the source of the first additive element, an aqueous solution containing the above compound is prepared.

[0343] <Chelating Agent> The chelating agent 83 shown in FIG. 16 will now be described. Examples of materials constituting the chelating agent include glycine, oxine, 1-nitroso-2-naphthol, 2-mercaptobenzothiazole, and EDTA (ethylenediaminetetraacetic acid). It is also possible to use multiple species selected from glycine, oxine, 1-nitroso-2-naphthol, and 2-mercaptobenzothiazole. An aqueous solution of these dissolved in pure water serves as a chelating agent, and an aqueous solution containing glycine may be referred to as a glycine aqueous solution. A chelating agent is a complexing agent that forms a chelate compound and is preferable to general complexing agents. Of course, a complexing agent may be used instead of a chelating agent, and ammonia water may be used as the complexing agent.

[0344] The use of a chelating agent is preferred because it makes it easier to control the pH of the reaction tank when obtaining a coprecipitate, such as a cobalt compound. The use of a chelating agent is also preferred because it suppresses the generation of unwanted crystal nuclei and promotes their growth. Suppressing the generation of unwanted nuclei suppresses the generation of fine particles, resulting in a composite oxide with a good particle size distribution. The use of a chelating agent also slows down the acid-base reaction, allowing the reaction to proceed gradually, resulting in the production of nearly spherical secondary particles.

[0345] Glycine has the effect of maintaining a constant pH value at or near a pH of 9 to 10, and the use of an aqueous glycine solution as a chelating agent is preferred because it facilitates control of the pH in the reaction vessel when obtaining the cobalt compound. Furthermore, the glycine concentration of the aqueous glycine solution is preferably 0.05 mol / L to 0.09 mol / L in the aqueous solution.

[0346] <Pure Water> The aqueous solution used in this embodiment is preferably pure water. Pure water is water with a resistivity of 1 MΩ cm or more, more preferably 10 MΩ cm or more, and even more preferably 15 MΩ cm or more. Water that satisfies this resistivity has high purity and contains very few impurities.

[0347] <Step S14> Next, in step S14 shown in FIG. 16, a transition metal M source 81 and a chelating agent 83 are mixed to prepare an acidic solution 91.

[0348] <Alkaline Solution> Next, the alkaline solution 84 shown in Fig. 16 will be described. The alkaline solution may be, for example, an aqueous solution containing sodium hydroxide, potassium hydroxide, lithium hydroxide, or ammonia, and is not limited to these aqueous solutions as long as it functions as a pH adjuster. For example, it may be an aqueous solution in which two or more species selected from sodium hydroxide, potassium hydroxide, and lithium hydroxide are dissolved in water. The water used may be pure water as described above.

[0349] Water or an aqueous solution may be prepared together with the alkaline solution 84. The water or aqueous solution may be referred to as a charging solution or an adjusting solution, and may refer to any aqueous solution in the initial reaction state. The water may be the above-mentioned pure water. A chelating agent containing the above-mentioned pure water may also be used as the aqueous solution. When a chelating agent is used, the effects described above in <Chelating Agent> are achieved. It is not necessary to prepare water or an aqueous solution.

[0350] 16, step S31 will be described. In step S31, the acidic solution 91 and the alkaline solution 84 are mixed. By mixing, the acidic solution 91 and the alkaline solution 84 react with each other, and a coprecipitate 95 can be obtained.

[0351] The reaction in step 31 may be referred to as a neutralization reaction, an acid-base reaction, or a co-precipitation reaction. The resulting coprecipitate 95 may be referred to as a precursor of the positive electrode active material.

[0352] <Reaction Conditions> When the acidic solution 91 and the alkaline solution 84 are mixed according to the coprecipitation method, the pH of the reaction system is adjusted to 9 or more and 11 or less, preferably 9.8 or more and 10.3 or less. For example, when the acidic solution 91 is placed in a reaction vessel (e.g., a beaker) and the alkaline solution 84 is added dropwise to the reaction vessel, it is preferable that the pH of the aqueous solution in the reaction vessel satisfy or maintain the above-mentioned range. "Maintaining the above-mentioned range" includes, when the pH value of the aqueous solution in the reaction vessel fluctuates upon the addition of the alkaline solution 84, the pH of the aqueous solution in the reaction vessel satisfies the above-mentioned range a certain time after the addition. The certain time is 1 second to 5 seconds, preferably 1 second to 3 seconds. Similarly, when the alkaline solution 84 is placed in a reaction vessel and the acidic solution 91 is added dropwise, it is preferable that the pH of the aqueous solution in the reaction vessel satisfy or maintain the above-mentioned range. The dropping speed of the acidic solution 91 or alkaline solution 84 is preferably set to 0.2 mL / min or more and 0.8 mL / min or less, in consideration of ease of control of the pH conditions.

[0353] In the reaction vessel, the alkaline solution 84 or the acidic solution 91 may be stirred using a stirring means. A stirrer may be used as the stirring means, and specifically, a stirrer with stirring blades may be used. The stirrer may be provided with two to six stirring blades. For example, when using four stirring blades, they may be arranged in a cross shape when viewed from above. The rotation speed of the stirring means may be 800 rpm to 1200 rpm.

[0354] The alkaline solution 84 or the acidic solution 91 in the reaction vessel is adjusted to a temperature of 50° C. or higher and 90° C. or lower. The dropping of either the alkaline solution 84 or the acidic solution 91 may be started after the solution has reached the appropriate temperature.

[0355] The inside of the reaction vessel is preferably an inert atmosphere. For example, when a nitrogen atmosphere is used, nitrogen gas is preferably introduced at a flow rate of 0.5 L / min to 2 L / min.

[0356] The reaction vessel may also be equipped with a reflux condenser, which allows nitrogen gas to escape from the reaction vessel. Water produced by reflux condensation can be returned to the reaction vessel.

[0357] After the above reaction, a cobalt compound, for example, precipitates in the reaction vessel as a coprecipitate 95. Filtration is preferably performed to recover the coprecipitate 95. During filtration, it is preferable to wash the reaction product precipitated in the reaction vessel with pure water, and then perform a new filtration using an organic solvent with a low boiling point (e.g., acetone). The filtration may be performed by suction filtration.

[0358] The filtered coprecipitate 95 is preferably further dried. For example, the coprecipitate 95 may be dried for 0.5 to 3 hours in a vacuum atmosphere at a temperature of 60 to 90° C. The coprecipitate 95 may be obtained through such a procedure.

[0359] The cobalt compound coprecipitate 95 is cobalt hydroxide (e.g., Co(OH) ２ After filtration, the cobalt hydroxide is obtained as secondary particles formed by aggregation of primary particles.

[0360] <Lithium Source> Next, a lithium compound is prepared as the lithium source 88 (referred to as Li source in the drawing) shown in Fig. 16. As the lithium compound, lithium hydroxide, lithium carbonate, lithium oxide, or lithium nitrate is prepared. For example, when cobalt hydroxide is obtained as the coprecipitate 95, lithium hydroxide can be used as the lithium compound.

[0361] The lithium compound should be crushed in advance. The mortar is preferably made of a material that does not release impurities, specifically, an alumina mortar with a purity of 90% or more, preferably 99% or more, should be used. Wet crushing using a ball mill may also be used. In wet crushing, acetone can be used as the solvent.

[0362] <Step S41> Next, in step S41 shown in Fig. 16, the coprecipitate 95 and the lithium source 88 are mixed. Thereafter, a mixed mixture 97 is obtained. A revolutionary agitator may be used as a means for mixing the coprecipitate 95 and the lithium source 88. Because the revolutionary agitator does not use media, pulverization is often not performed.

[0363] When the coprecipitate 95 and the lithium source 88 are mixed and pulverized simultaneously, a ball mill or a bead mill can be used. Alumina balls or zirconia balls can be used as media for the ball mill or bead mill. In the ball mill or bead mill, centrifugal force is applied to the media, making it possible to pulverize the material. When contamination from the media or the like is a concern, it is preferable to use the zirconia balls.

[0364] When pulverization is performed simultaneously, there are dry pulverization and wet pulverization. Dry pulverization is performed in an inert gas or air, and can pulverize to a particle size of 3.5 μm or less, preferably 3 μm or less. Wet pulverization is performed in a liquid, and can pulverize to a particle size of nanometers. In other words, wet pulverization is recommended when a smaller particle size is desired.

[0365] In this way, mixture 97 is obtained.

[0366] <Step S44> Next, in step S44 shown in Fig. 16, the mixture is heated. Step S44 may be referred to as main baking. After heating, a composite oxide can be obtained as positive electrode active material 90. Positive electrode active material 90 may reflect the shape of coprecipitate 95, which is its precursor.

[0367] <Heating Conditions> The heating temperature is preferably 700° C. or higher and lower than 1100° C., more preferably 800° C. or higher and 1000° C. or lower, and even more preferably 800° C. or higher and 950° C. or lower. In order to produce cobalt oxide through this heat treatment, heating is performed at a temperature at which at least the coprecipitate 95 and the lithium source 88 diffuse into each other. This temperature is the reason why the process is called the main calcination.

[0368] The heating time can be, for example, from 1 hour to 100 hours, and is preferably from 2 hours to 20 hours.

[0369] The heating is preferably carried out in an oxygen-containing atmosphere or a so-called dry air atmosphere containing oxygen with little water (for example, a dew point of -50°C or less, more preferably a dew point of -80°C or less).

[0370] For example, when heating at 750°C for 10 hours, the temperature rise rate should be 150°C / hour or more and 250°C / hour or less. The flow rate of dry air that can constitute the drying atmosphere is preferably 3 L / min or more and 10 L / min or less. The temperature drop time is preferably 10 hours or more and 50 hours or less until the temperature drops from the specified temperature to room temperature, and the temperature drop rate can be calculated from the temperature drop time, etc.

[0371] The crucible, sheath, setter, or container used during heating is preferably made of a material that does not release impurities. For example, it is recommended to use a crucible made of alumina with a purity of 99.9%. For mass production, mullite-cordierite (Al ２ O ３ , SiO ２ , MgO) sheaths are preferably used.

[0372] Furthermore, when recovering the material after heating, it is preferable to transfer it from the crucible to a mortar and then recover it, since this prevents impurities from being mixed into the material. The mortar is also preferably made of a material that does not release impurities, and specifically, a mortar made of alumina or zirconia with a purity of 90% or more, preferably 99% or more, may be used.

[0373] As described above, the positive electrode active material 90 can be produced, and according to Production Method 1, an NCM can be obtained as the positive electrode active material 90. The NCM may be referred to as a composite oxide.

[0374] Manufacturing method 1 is preferable because it contains fewer impurities in positive electrode active material 90. However, when a sulfide is used as a starting material, sulfur may be detected in positive electrode active material 90. The sulfur concentration can be measured by performing elemental analysis of positive electrode active material 90 using GD-MS, ICP-MS, or the like.

[0375] As described above, in this embodiment, an example in which a positive electrode active material applicable to the above embodiment is produced by coprecipitation has been shown, but the present invention is not limited to the above example.

[0376] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0377] Sixth Embodiment In the present embodiment, a method for manufacturing a positive electrode active material 2 that can be applied to the above-described embodiments will be described. Unless otherwise specified, the method for manufacturing a positive electrode active material 2 shown in the present embodiment can be applied to a room temperature battery or a low temperature battery.

[0378] Specifically, a method for producing a positive electrode active material by a liquid phase method will be described with reference to Fig. 17 etc. The production method will be described.

[0379] 17, a lithium compound 803 is prepared. In step S21b, a phosphorus compound 804 is prepared.

[0380] Here, the atomic ratio of lithium, transition metal M, and phosphorus in a composite oxide that is preferably obtained as a cathode active material 90 described later is defined as x:y:z. ４ To obtain this, for example, x:y:z=1:1:1 should be used.

[0381] Representative examples of lithium compounds include lithium chloride (LiCl) and lithium acetate (CH ３ COOLi), lithium oxalate ((COOLi) ２ ), lithium carbonate (Li ２ CO ３ ), lithium hydroxide monohydrate (LiOH·H ２ O) etc.

[0382] Representative examples of phosphorus compounds include orthophosphoric acid (H ３ P.O. ４ ) and other phosphoric acids, diammonium hydrogen phosphate ((NH ４ ) ２ HPO ４ ), ammonium dihydrogen phosphate (NH ４ H ２ P.O. ４ ) and other ammonium hydrogen phosphates.

[0383] Next, in step S21c of FIG. 17 , a solvent 805 is prepared. It is preferable to use water as the solvent 805. Alternatively, a mixture of water and another liquid may be used as the solvent 805. For example, water and alcohol may be mixed. Here, the lithium compound 803 and the phosphorus compound 804, or the reaction product of the lithium compound 803 and the phosphorus compound 804, may have different solubilities in water and alcohol. Using alcohol may result in smaller particle sizes. Furthermore, using alcohol with a boiling point lower than that of water may make it easier to increase the pressure in step S83, which will be described later.

[0384] When water is used as the solvent 805, it is desirable that the water be pure water with a low impurity content and a specific resistance of preferably 1 MΩ cm or more, more preferably 10 MΩ cm or more, and even more preferably 15 MΩ cm or more. By using a highly pure material, the capacity and / or reliability of the secondary battery can be increased.

[0385] Next, in step S31 of FIG. 17 , a lithium compound 803, a phosphorus compound 804, and a solvent 805 are mixed to obtain a mixture 811 in step S32. The mixing in step S31 can be performed in an atmosphere such as air or an inert gas. Nitrogen, for example, may be used as the inert gas. Here, as an example, the lithium compound 803 prepared in step S21a, the phosphorus compound 804 prepared in step S21b, and the solvent 805 prepared in step S21c are mixed in an air atmosphere. For example, the lithium compound 803 prepared in step S21a and the phosphorus compound 804 prepared in step S21b are added to the solvent 805 prepared in step S21c to form the mixture 811 in step S32.

[0386] 17 , the lithium compound 803, the phosphorus compound 804, and the reaction products of the lithium compound and the phosphorus compound may precipitate in the solution, but some of them dissolve in the solvent without precipitating, i.e., exist in the solvent as ions. Here, if the pH of the mixture 811 is low, the reaction products may be easily dissolved in the solvent, and if the pH is high, the reaction products may be easily precipitated.

[0387] It should be noted that instead of mixing the lithium compound 803 and the phosphorus compound 804 to form the mixture 811 in step S32, Li ３ P.O. ４ , Li ２ HPO ４ , LiH ２ P.O. ４ A compound having phosphorus and lithium, such as, may be prepared and added to a solvent to form the mixture 811 in step S32.

[0388] Here, when the mixture 811 in step S32 is an aqueous solution, the pH of the mixture 811 is determined by the type and degree of dissociation of the salt contained in the mixture 811. Therefore, the pH of the mixture 811 varies depending on the lithium compound 803 and the phosphorus compound 804 used as raw materials. For example, when lithium chloride is used as the lithium compound 803 and orthophosphoric acid is used as the phosphorus compound 804, the mixture 811 in step S32 becomes a strong acid. Furthermore, when lithium hydroxide monohydrate is used as the lithium compound 803, the mixture 811 in step S32 tends to become alkaline.

[0389] Next, in step S33 of FIG. 17, a solution P812 is prepared. Next, in step S35, the mixture 811 of step S32 and the solution P812 prepared in step S33 are mixed to form a mixture 821 of step S41. Here, the pH of the mixture 821 of step S41 obtained and the mixture 831 of step S82 obtained later can be adjusted by adjusting the amount or concentration of the solution P812 added. In step S35, for example, the solution P812 may be added dropwise while measuring the pH of the mixture 811 of step S32. As the solution P812, an alkaline solution or an acidic solution is used depending on the pH of the mixture 811 of step S32. Here, using a weak alkaline or weak acidic solution may make it easier to adjust the pH. For example, the pH of the alkaline solution may be 8 or more and 12 or less. The pH of the acidic solution may be 2 or more and 6 or less. For example, ammonia water may be used as the alkaline solution. It is preferable to determine the pH and mixing amount of the solution P812 so that the mixture 831 in step S82 described below is acidic or neutral.

[0390] 17, a transition metal M source 822 is prepared. As the transition metal M source 822, one or more of an iron(II) compound, a manganese(II) compound, a cobalt(II) compound, and a nickel(II) compound (hereinafter referred to as an M(II) compound) can be used.

[0391] It is preferable to use a high-purity material as the transition metal M source used in the synthesis. Specifically, the purity of the material is 3N (99.9%) or higher, preferably 4N (99.99%) or higher, more preferably 4N (99.995%) or higher, and even more preferably 5N (99.999%) or higher. Using a high-purity material can increase the capacity or reliability of the battery cell.

[0392] In addition, it is preferable that the transition metal M source has high crystallinity. For example, it is preferable that the transition metal source has single crystal grains. The crystallinity of the transition metal source can be evaluated, for example, from a TEM (transmission electron microscope) image, a STEM (scanning transmission electron microscope) image, a HAADF-STEM (high-angle annular dark-field scanning transmission electron microscope) image, an ABF-STEM (annular bright-field scanning transmission electron microscope) image, etc. Furthermore, X-ray diffraction (XRD), electron diffraction, neutron diffraction, etc. can also be used to evaluate the crystallinity of the transition metal source. Note that the above-mentioned crystallinity evaluation can be applied not only to the transition metal source, but also to the evaluation of the crystallinity of primary particles or secondary particles.

[0393] Representative examples of iron (II) compounds include iron chloride tetrahydrate (FeCl ２ ・4H ２ O), iron sulfate heptahydrate (FeSO ４ ・7H ２ O), iron acetate (Fe(CH ３ COO) ２ ) etc.

[0394] Representative examples of manganese(II) compounds include manganese chloride tetrahydrate (MnCl ２ ・4H ２ O), manganese sulfate monohydrate (MnSO ４ ・H ２ O), manganese acetate tetrahydrate (Mn(CH ３ COO) ２ ・4H ２ O) etc.

[0395] Representative examples of cobalt (II) compounds include cobalt chloride hexahydrate (CoCl ２ ・6H ２ O), cobalt sulfate heptahydrate (CoSO ４ ・7H ２ O), cobalt acetate tetrahydrate (Co(CH ３ COO) ２ ・4H ２ O) etc.

[0396] Representative examples of nickel (II) compounds include nickel chloride hexahydrate (NiCl ２ ・6H ２O), nickel sulfate hexahydrate (NiSO ４ ・6H ２ O), nickel acetate tetrahydrate (Ni(CH ３ COO) ２ ・4H ２ O) etc.

[0397] In step S42, the compound may be prepared as an aqueous solution as the transition metal M source 822. When preparing the compound as an aqueous solution, the water used is preferably pure water with a low impurity content, and having a resistivity of preferably 1 MΩ cm or more, more preferably 10 MΩ cm or more, and even more preferably 15 MΩ cm or more.

[0398] Next, in step S41 of FIG. 17, the mixture 821 of step S41 and a transition metal M source 822 are mixed to obtain a mixture 831 of step S82.

[0399] Here, in step S41, a solvent can be added to reduce the concentration of the mixture 831 of step S82. For example, in step S41, the mixture 821 of step S41, the transition metal M source 822, and a solvent can be mixed to prepare the mixture 831 of step S82.

[0400] Next, in step S83 of FIG. 17 , the mixture 831 from step S82 is placed in a heat-resistant, pressure-resistant container such as an autoclave, and heated to a temperature of 100°C to 350°C, preferably greater than 100°C and less than 200°C, and a pressure of 0.11 MPa to 100 MPa, more preferably 0.11 MPa to 2 MPa, for 0.5 hours to 24 hours, more preferably 1 hour to 10 hours, and even more preferably 1 hour to less than 5 hours, followed by cooling. Subsequently, in step S44, the solution in the heat-resistant, pressure-resistant container is filtered and washed with water. Next, in step S85, the solution is dried and then recovered, yielding a positive electrode active material 90 in step S86. The positive electrode active material 90 can be described as a composite oxide.

[0401] The obtained positive electrode active material 90 was LiMPO ４(M is one or more of Fe(II), Ni(II), Co(II), and Mn(II)). A specific example of the positive electrode active material 90 is LiFePO ４ (LFP), LiNiPO ４ , LiCoPO ４ , LiMnPO ４ , LiFe ａ Ni ｂ P.O. ４ , LiFe ａ Co ｂ P.O. ４ , LiFe ａ Mn ｂ P.O. ４ , LiNi ａ Co ｂ P.O. ４ , LiNi ａ Mn ｂ P.O. ４ (a+b is 1 or less, 0<a<1, 0<b<1), LiFe ｃ Ni ｄ Co ｅ P.O. ４ , LiFe ｃ Ni ｄ Mn ｅ P.O. ４ , LiNi ｃ Co ｄ Mn ｅ P.O. ４ (c+d+e is 1 or less, 0<c<1, 0<d<1, 0<e<1), LiFe ｆ Ni ｇ Co ｈ Mn ｉ P.O. ４ (f+g+h+i is 1 or less, 0<f<1, 0<g<1, 0<h<1, 0<i<1), etc. Among the above, LFP is highly safe and suitable as an active material for electric vehicles. LLFP is also inexpensive and suitable as an active material for electric vehicles.

[0402] The composite oxide obtained in this embodiment is preferably highly crystalline. A composite oxide with high crystallinity can suppress cycle deterioration, etc. The composite oxide may also be in the form of a single crystal grain.

[0403] The crystal structure of the positive electrode active material 90 can be identified by performing crystal analysis such as XRD or electron beam diffraction on the positive electrode active material 90. For example, LiMPO having an olivine-type crystal structure ４ is identified as belonging to the space group Pnma.

[0404] As described above, in this embodiment, an example in which a positive electrode active material applicable to the above embodiment is produced by a hydrothermal method has been shown, but the present invention is not limited to the above example.

[0405] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0406] Seventh Embodiment In this embodiment, a method for manufacturing a positive electrode active material 3 that can be applied to the above-described embodiments will be described. Unless otherwise specified, the method for manufacturing a positive electrode active material 3 shown in this embodiment can be applied to a room temperature battery or a low temperature battery.

[0407] Specifically, a method for producing a positive electrode active material by a liquid phase method will be described with reference to Fig. 18 etc. The production method will be described.

[0408] 18, a solution 806 containing lithium is prepared. In step S21b, a solution 807 containing phosphorus is prepared.

[0409] The solution 806 containing lithium can be prepared by dissolving a lithium compound in a solvent. The lithium compound may be lithium hydroxide monohydrate (LiOH·H ２ O), lithium chloride (LiCl), lithium carbonate (Li ２ CO ３ ), lithium acetate (CH ３ COOLi), lithium oxalate ((COOLi) ２), or any one or more of the following can be used. An example of a solvent for dissolving a lithium compound is water. When water is used as the solvent, it is desirable that it be pure water with a low impurity content, preferably with a specific resistance of 1 MΩ cm or more, more preferably with a specific resistance of 10 MΩ cm or more, and even more preferably with a specific resistance of 15 MΩ cm or more. By using a highly pure material, it is possible to increase the capacity of the secondary battery and / or improve the reliability of the secondary battery.

[0410] The phosphorus-containing solution 807 can be prepared by dissolving a phosphorus compound in a solvent. ３ P.O. ４ ) or diammonium hydrogen phosphate ((NH ４ ) ２ HPO ４ ), or ammonium dihydrogen phosphate (NH ４ H ２ P.O. ４ ammonium hydrogen phosphate, etc.), can be used. Water is an example of a solvent for dissolving phosphorus compounds. When water is used as the solvent, it is desirable to use pure water with few impurities, preferably with a specific resistance of 1 MΩ cm or more, more preferably 10 MΩ cm or more, and even more preferably 15 MΩ cm or more. The use of highly pure materials can increase the capacity or reliability of the battery cell.

[0411] 18, a lithium-containing solution 806 and a phosphorus-containing solution 807 are mixed to obtain a mixture 811 in step S32. The mixing in step S31 can be performed in an atmosphere such as air or an inert gas. Nitrogen, for example, can be used as the inert gas. Here, as an example, the lithium-containing solution 806 prepared in step S21a and the phosphorus-containing solution 807 prepared in step S21b are mixed in an air atmosphere.

[0412] It should be noted that instead of mixing the lithium-containing solution 806 and the phosphorus-containing solution 807 to form the mixture 811 in step S32, Li ３ P.O. ４ , Li ２ HPO４ , LiH ２ P.O. ４ A compound having phosphorus and lithium, such as, may be prepared and added to a solvent to form the mixture 811 in step S32.

[0413] Next, in step S33 of FIG. 18, a solution 813 containing a transition metal M is prepared.

[0414] The solution 813 containing the transition metal M can be prepared by dissolving a transition metal M compound in a solvent. The transition metal M compound can be one or more of an iron (II) compound, a manganese (II) compound, a cobalt (II) compound, and a nickel (II) compound (hereinafter referred to as an M (II) compound). An example of a solvent for dissolving the transition metal M compound is water. When water is used as the solvent, it is desirable to use pure water with few impurities, preferably with a resistivity of 1 MΩ·cm or more, more preferably 10 MΩ·cm or more, and even more preferably 15 MΩ·cm or more. Using a highly pure material can increase the capacity or reliability of the battery cell.

[0415] It is preferable to use a high-purity material as the transition metal M compound used in the synthesis. Specifically, the purity of the material is 3N (99.9%) or higher, preferably 4N (99.99%) or higher, more preferably 4N (99.995%) or higher, and even more preferably 5N (99.999%) or higher. Using a high-purity material can increase the capacity or reliability of the battery cell.

[0416] In addition, it is preferable that the transition metal M compound has high crystallinity. For example, it is preferable that the transition metal compound has single crystal grains. The crystallinity of the transition metal compound can be evaluated, for example, from TEM (transmission electron microscope) images, STEM (scanning transmission electron microscope) images, HAADF-STEM (high-angle annular dark-field scanning transmission electron microscope) images, ABF-STEM (annular bright-field scanning transmission electron microscope) images, etc. Furthermore, X-ray diffraction (XRD), electron diffraction, neutron diffraction, etc. can also be used to evaluate the crystallinity of the transition metal M compound. Note that the above-mentioned crystallinity evaluation can be applied not only to transition metal M compounds but also to the evaluation of the crystallinity of primary particles or secondary particles.

[0417] Representative examples of iron (II) compounds include iron chloride tetrahydrate (FeCl ２ ・4H ２ O), iron sulfate heptahydrate (FeSO ４ ・7H ２ O), iron acetate (Fe(CH ３ COO) ２ ) etc.

[0418] Representative examples of manganese(II) compounds include manganese chloride tetrahydrate (MnCl ２ ・4H ２ O), manganese sulfate monohydrate (MnSO ４ ・H ２ O), manganese acetate tetrahydrate (Mn(CH ３ COO) ２ ・4H ２ O) etc.

[0419] Representative examples of cobalt (II) compounds include cobalt chloride hexahydrate (CoCl ２ ・6H ２ O), cobalt sulfate heptahydrate (CoSO ４ ・7H ２ O), cobalt acetate tetrahydrate (Co(CH ３ COO) ２ ・4H ２ O) etc.

[0420] Representative examples of nickel (II) compounds include nickel chloride hexahydrate (NiCl ２ ・6H ２O), nickel sulfate hexahydrate (NiSO ４ ・6H ２ O), nickel acetate tetrahydrate (Ni(CH ３ COO) ２ ・4H ２ O) etc.

[0421] Next, in step 35 of FIG. 18, the mixture 811 of step S32 and a solution 813 containing a transition metal M are mixed to obtain a mixture 823 of step S41.

[0422] Here, the atomic ratio of lithium, transition metal M, and phosphorus in a composite oxide that is preferably obtained as a cathode active material 90 described later is defined as x:y:z. ４ To obtain this, for example, x:y:z=1:1:1 should be used.

[0423] 18, a solution 813 containing a transition metal M can be added dropwise little by little to the mixture 811 of step S32 placed in a container to prepare a mixture 823 of step S41. During mixing, it is desirable to stir the solution in the container and the solution used for mixing. ２ It is desirable to remove dissolved oxygen by bubbling.

[0424] Alternatively, as a method of mixing in step S35 in Fig. 18, the mixture 811 in step S32 can be added dropwise little by little to a solution 813 containing the transition metal M placed in a container to prepare a mixture 823 in step S41. In mixing, it is desirable to stir the solution in the container and the solution used for mixing. ２ It is desirable to remove dissolved oxygen by bubbling.

[0425] Here, in step S35, a solvent can be added to adjust the concentration of the mixture 823 of step S41. For example, in step S35, the mixture 811 of step S32, the solution 813 containing the transition metal M, and a solvent can be mixed to produce the mixture 823 of step S41. When water is used as the solvent, it is desirable that the solvent be pure water with few impurities, preferably having a resistivity of 1 MΩ cm or more, more preferably 10 MΩ cm or more, and even more preferably 15 MΩ cm or more.

[0426] Next, in step S83 of FIG. 18 , the mixture 823 from step S41 is placed in a heat-resistant, pressure-resistant container such as an autoclave, and then heated to a temperature of 100°C to 350°C, preferably greater than 100°C and less than 200°C, and a pressure of 0.11 MPa to 100 MPa, more preferably 0.11 MPa to 2 MPa, for 0.5 hours to 24 hours, more preferably 1 hour to 10 hours, and even more preferably 1 hour to less than 5 hours, followed by cooling. Subsequently, in step S44, the solution in the heat-resistant, pressure-resistant container is filtered and washed with water. Next, in step S85, the solution is dried and then recovered, yielding a positive electrode active material 90 in step S86. The positive electrode active material 90 can be described as a composite oxide.

[0427] The obtained positive electrode active material 90 was LiMPO ４ (M is one or more of Fe(II), Ni(II), Co(II), and Mn(II)). A specific example of the positive electrode active material 90 is LiFePO ４ (LFP), LiNiPO ４ , LiCoPO ４ , LiMnPO ４ , LiFe ａ Ni ｂ P.O. ４ , LiFe ａ Co ｂ P.O. ４ , LiFe ａ Mn ｂ P.O. ４ , LiNi ａ Co ｂ P.O. ４ , LiNi ａ Mn ｂ P.O.４ (a+b is 1 or less, 0<a<1, 0<b<1), LiFe ｃ Ni ｄ Co ｅ P.O. ４ , LiFe ｃ Ni ｄ Mn ｅ P.O. ４ , LiNi ｃ Co ｄ Mn ｅ P.O. ４ (c+d+e is 1 or less, 0<c<1, 0<d<1, 0<e<1), LiFe ｆ Ni ｇ Co ｈ Mn ｉ P.O. ４ (f+g+h+i is 1 or less, 0<f<1, 0<g<1, 0<h<1, 0<i<1), etc. Among the above, LFP is highly safe and suitable as an active material for electric vehicles. LFP is also inexpensive and suitable as an active material for electric vehicles.

[0428] The composite oxide obtained in this embodiment is preferably highly crystalline. A composite oxide with high crystallinity can suppress cycle deterioration, etc. The composite oxide may also be in the form of a single crystal grain.

[0429] The crystal structure of the positive electrode active material 90 can be identified by performing crystal analysis such as XRD or electron beam diffraction on the positive electrode active material 90. For example, LiMPO having an olivine-type crystal structure ４ is identified as belonging to the space group Pnma.

[0430] As described above, in this embodiment, an example in which a positive electrode active material applicable to the above embodiment is produced by a hydrothermal method has been shown, but the present invention is not limited to the above example.

[0431] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0432] In this embodiment, an all-solid-state battery will be described as a battery cell that can be applied to the above-described embodiment. The all-solid-state battery using a positive electrode active material described in this embodiment can be applied to a room temperature battery or a low temperature battery unless otherwise specified.

[0433] As shown in FIG. 19A , a battery cell 400 of one embodiment of the present invention is an all-solid-state battery and includes a positive electrode 410 , a solid electrolyte layer 420 , and a negative electrode 430 .

[0434] The positive electrode 410 includes a positive electrode current collector 413 and a positive electrode active material layer 414. The positive electrode active material layer 414 includes a positive electrode active material 411 and a solid electrolyte 421. The positive electrode active material layer 414 may also include a conductive additive and a binder.

[0435] Solid electrolyte layer 420 includes solid electrolyte 421. Solid electrolyte layer 420 is located between positive electrode 410 and negative electrode 430, and is a region that does not include either positive electrode active material 411 or negative electrode active material 431.

[0436] The negative electrode 430 includes a negative electrode current collector 433 and a negative electrode active material layer 434. The negative electrode active material layer 434 includes a negative electrode active material 431 and a solid electrolyte 421. The negative electrode active material layer 434 may also include a conductive additive and a binder. Note that when metallic lithium is used as the negative electrode active material 431, it is not necessary to form the material into particles, and therefore the negative electrode 430 can be formed without the solid electrolyte 421, as shown in FIG. 19B . Using metallic lithium for the negative electrode 430 is preferable because it can improve the energy density of the battery cell 400.

[0437] The solid electrolyte 421 of the solid electrolyte layer 420 may be, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a halide-based solid electrolyte.

[0438] Again, sulfide-based solid electrolytes include thiolithium-based (Li １０ GeP ２ S １２ , Li ３．２５ Ge ０．２５ P ０．７５ S ４ etc.), sulfide glass (70Li ２ S・30P ２ S530Li ２ S・26B ２ S ３ ・44LiI, 63Li ２ S・36SiS ２ ・1Li ３ P.O. ４ , 57Li ２S・38SiS ２ ・5Li ４ SiO ４ , 50Li ２ S・50GeS ２ etc.), sulfide crystallized glass (Li ７ P ３ S １１ , Li ３．２５ P ０．９５ S ４ Sulfide-based solid electrolytes have the advantages of being highly conductive, being able to be synthesized at low temperatures, and being relatively soft, which makes it easy to maintain conductive paths even after charging and discharging.

[0439] To reiterate, oxide-based solid electrolytes include materials with a perovskite crystal structure (La ２／３−ｘ Li ３ｘ TiO ３ etc.), materials having a NASICON type crystal structure (Li １＋Ｙ Al Ｙ Ti ２−Ｙ (P.O. ４ ) ３ etc.), materials having a garnet-type crystal structure (Li ７ La ３ Zr ２ O １２ etc.), materials having a LISICON type crystal structure (Li １４ ZnGe ４ O １６ etc.), LLZO (Li ７ La ３ Zr ２ O １２ ), oxide glass (Li ３ P.O. ４ -Li ４ SiO ４ , 50Li ４ SiO ４ ・50Li ３ BO ３ etc.), oxide crystallized glass (Li １．０７ Al ０．６９ Ti １．４６ (P.O. ４ ) ３ , Li １．５ Al ０．５ Ge １．５ (P.O. ４ ) ３Oxide-based solid electrolytes have the advantage of being stable in the atmosphere.

[0440] Again, the halide solid electrolyte is LiAlCl ４ , Li ３ InBr ６ , LiF, LiCl, LiBr, LiI, etc. Furthermore, composite materials in which these halide-based solid electrolytes are filled into the pores of porous aluminum oxide or porous silica can also be used as the solid electrolyte.

[0441] Also, different solid electrolytes may be mixed and used.

[0442] Again, Li having a NASICON type crystal structure １＋ｘ Al ｘ Ti ２−ｘ (P.O. ４ ) ３ Since (0[x[1) (hereinafter referred to as LATP) contains aluminum and titanium, which are elements that may be contained in the positive electrode active material used in the battery cell of one embodiment of the present invention, a synergistic effect can be expected in improving cycle characteristics, which is preferable. In addition, an improvement in productivity due to a reduction in the number of steps can also be expected. In this specification and the like, the NASICON-type crystal structure refers to a structure having a structure such as M ２ (XO ４ ) ３ (M: transition metal, X: S, P, As, Mo, W, etc.), ６ Octahedron and XO ４ It refers to a structure in which tetrahedrons are arranged three-dimensionally with their vertices shared.

[0443] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0444] 21A and 21B, the other configuration examples of the battery cell shown in this embodiment mode can be applied to a room temperature battery or a low temperature battery unless otherwise specified.

[0445] 20A and 20B is a laminated battery cell. 20A and 20B include a positive electrode 503, a negative electrode 506, a separator 507, an outer casing 509, a positive electrode lead electrode 510, and a negative electrode lead electrode 511.

[0446] 20A shows an external view of a positive electrode 503 and a negative electrode 506. The positive electrode 503 has a positive electrode current collector 501, and a positive electrode active material layer 502 is formed on the surface of the positive electrode current collector 501. The positive electrode 503 also has a region where the positive electrode current collector 501 is partially exposed (hereinafter referred to as a tab region). The negative electrode 506 has a negative electrode current collector 504, and a negative electrode active material layer 505 is formed on the surface of the negative electrode current collector 504. The negative electrode 506 also has a region where the negative electrode current collector 504 is partially exposed, i.e., a tab region. Note that the area or shape of the tab regions of the positive electrode and negative electrode are not limited to the example shown in FIG. 20A .

[0447] <Method for Manufacturing Laminated Battery Cell> An example of a method for manufacturing a laminated battery cell, the external view of which is shown in FIG. 20A, will be described with reference to FIGS. 21A and 21B.

[0448] First, as shown in FIG. 21A , a negative electrode 506, a separator 507, and a positive electrode 503 are stacked. Here, an example is shown in which five negative electrodes and four positive electrodes are used. This can also be called a laminate consisting of a negative electrode, a separator, and a positive electrode. Next, the tab regions of the positive electrodes 503 are joined together, and a positive electrode lead electrode 510 is joined to the tab region of the positive electrode on the outermost surface. For example, ultrasonic welding or the like may be used for joining. Similarly, the tab regions of the negative electrodes 506 are joined together, and a negative electrode lead electrode 511 is joined to the tab region of the negative electrode on the outermost surface.

[0449] Next, the negative electrode 506 , the separator 507 and the positive electrode 503 are arranged on the outer casing 509 .

[0450] Next, as shown in Fig. 21B, the exterior body 509 is folded at the portion indicated by the dashed line. Thereafter, the outer periphery of the exterior body 509 is joined. For example, thermocompression bonding or the like may be used for joining. At this time, an area (hereinafter referred to as an inlet) that is not joined is provided in a part (or one side) of the exterior body 509 so that an electrolyte can be introduced later.

[0451] Next, an electrolyte (not shown) is introduced into the inside of the exterior body 509 through an inlet provided in the exterior body 509. The introduction of the electrolyte is preferably carried out under a reduced pressure atmosphere or an inert atmosphere. Finally, the inlet is joined. In this manner, a laminated battery cell can be produced.

[0452] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0453] 22A to 22C, 23A to 23C, and 24A to 24D. The other configuration examples of the battery cell shown in this embodiment can be applied to a room-temperature battery or a low-temperature battery unless otherwise specified.

[0454] [Prismatic Battery Cell] The secondary battery 913 shown in FIG. 22A is a prismatic battery cell and includes a wound body 950 with terminals 951 and 952 provided inside a housing 930. The wound body 950 is immersed in an electrolyte inside the housing 930. The terminal 952 contacts the housing 930, and the terminal 951 is not in contact with the housing 930 due to the use of an insulating material or the like. Note that for convenience, the housing 930 is shown separated in FIG. 22A , but in reality, the wound body 950 is covered by the housing 930, and the terminals 951 and 952 extend outside the housing 930. The housing 930 can be made of a metal material (e.g., aluminum) or a resin material.

[0455] 22B, the housing 930 shown in Fig. 22A may be formed from a plurality of materials. For example, the secondary battery 913 shown in Fig. 22B has a housing 930a and a housing 930b bonded together, and a wound body 950 is provided in the area surrounded by the housing 930a and the housing 930b.

[0456] The housing 930a can be made of an insulating material such as organic resin. In particular, by using a material such as organic resin on the surface on which the antenna is formed, it is possible to suppress shielding of the electric field by the secondary battery 913. Note that if the shielding of the electric field by the housing 930a is small, the antenna may be provided inside the housing 930a. The housing 930b can be made of, for example, a metal material.

[0457] 22C shows the structure of the wound body 950. The wound body 950 has a negative electrode 931, a positive electrode 932, and a separator 933. The wound body 950 is a wound body in which the negative electrode 931 and the positive electrode 932 are stacked on top of each other with the separator 933 sandwiched therebetween, and the laminated sheet is wound. Note that multiple layers of the negative electrode 931, the positive electrode 932, and the separator 933 may be stacked.

[0458] Alternatively, a secondary battery 913 having a wound body 950a as shown in Figures 23A to 23C may be used as a rectangular battery cell. The wound body 950a shown in Figure 23A has a negative electrode 931, a positive electrode 932, and a separator 933. The negative electrode 931 has a negative electrode active material layer 931a. The positive electrode 932 has a positive electrode active material layer 932a.

[0459] The separator 933 has a width wider than the negative electrode active material layer 931 a and the positive electrode active material layer 932 a, and is wound so as to overlap the negative electrode active material layer 931 a and the positive electrode active material layer 932 a. From the standpoint of safety, it is preferable that the negative electrode active material layer 931 a be wider than the positive electrode active material layer 932 a. A wound body 950 a having such a shape is preferable due to its high safety and productivity.

[0460] 23B, the negative electrode 931 is electrically connected to a terminal 951. The terminal 951 is electrically connected to a terminal 911a. The positive electrode 932 is electrically connected to a terminal 952. The terminal 952 is electrically connected to a terminal 911b.

[0461] 23C , the wound body 950 a and the electrolyte are covered by the housing 930 to form the secondary battery 913. It is preferable to provide the housing 930 with a safety valve, an overcurrent protection element, etc. The safety valve is a valve that opens when the inside of the housing 930 reaches a predetermined internal pressure to prevent the battery from exploding.

[0462] As shown in Fig. 23B, the secondary battery 913 may have multiple wound bodies 950a. Using multiple wound bodies 950a can result in a secondary battery 913 with a larger charge / discharge capacity. For other elements of the secondary battery 913 shown in Figs. 23A and 23B, refer to the descriptions of the secondary battery 913 shown in Figs. 22A to 22C.

[0463] <Cylindrical Battery Cell> The secondary battery 600 shown in Fig. 24A is a cylindrical battery cell. Fig. 24B is a schematic diagram showing a cross section of the secondary battery 600. As shown in Fig. 24B, the secondary battery 600 has a positive electrode cap (battery lid) 601 on the top surface, and a battery can (external can) 602 on the side and bottom surfaces. The positive electrode cap and battery can (external can) 602 are insulated by a gasket (insulating packing) 610.

[0464] A battery element is provided inside a hollow cylindrical battery can 602, in which a strip-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 sandwiched between them. Although not shown, the battery element is wound around a center pin. One end of the battery can 602 is closed and the other end is open. The battery can 602 can be made of a metal such as nickel, aluminum, or titanium, or an alloy of these metals or an alloy of these metals with other metals (e.g., stainless steel), which are corrosion-resistant to the electrolyte. Furthermore, the battery can 602 is preferably coated with nickel, aluminum, or the like to prevent corrosion by the electrolyte. Inside the battery can 602, the wound battery element, in which the positive electrode, negative electrode, and separator are wound, is sandwiched between a pair of opposing insulating plates 608 and 609. A nonaqueous electrolyte (not shown) is poured into the battery can 602, in which the battery element is provided.

[0465] In a cylindrical battery cell, the positive and negative electrodes are wound, so it is preferable to form active material on both sides of the current collector. A positive electrode terminal (positive electrode current collector lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative electrode current collector lead) 607 is connected to the negative electrode 606. Both the positive electrode terminal 603 and the negative electrode terminal 607 can be made of a metal material such as aluminum. The positive electrode terminal 603 is resistance-welded to a safety valve mechanism 612, and the negative electrode terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 612 is electrically connected to the positive electrode cap 601 via a PTC (Positive Temperature Coefficient T) element 611. The safety valve mechanism 612 cuts off the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the internal pressure of the battery exceeds a predetermined threshold. The PTC element 611 is a thermosensitive resistor whose resistance increases when the temperature rises, and the increase in resistance limits the amount of current to prevent abnormal heat generation. ３ )-based semiconductor ceramics, etc. can be used.

[0466] 24C , a plurality of secondary batteries 600 may be sandwiched between conductive plates 613 and 614 to form an assembled battery 615. The plurality of secondary batteries 600 may be connected in parallel, in series, or in parallel and then in series. By forming an assembled battery 615 having a plurality of secondary batteries 600, a large amount of power can be extracted. The battery pack may include the assembled battery 615, a BMU, a temperature sensor, etc.

[0467] FIG. 24D is a top view of the battery pack 615. For clarity, the conductive plate 613 is shown with a dotted line. As shown in FIG. 24D, the battery pack 615 may have conductors 616 that electrically connect the multiple secondary batteries 600. A conductive plate can be superimposed on the conductors 616. A cooling device 617 may also be provided between the multiple secondary batteries 600 as a temperature control device. If the secondary batteries 600 overheat, they can be cooled by the cooling device 617. If a heating device is used as a temperature control device, the secondary batteries 600 can also be heated when they are too cold. This makes the performance of the battery pack 615 less susceptible to the effects of the outside air temperature.

[0468] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0469] Embodiment 11 In this embodiment, a vehicle or the like equipped with a battery control system or the like according to one embodiment of the present invention will be described as an example.

[0470] 25A to 25C illustrate examples of vehicles using a secondary battery according to one embodiment of the present invention. An automobile 8400 shown in FIG. 25A is an electric automobile using an electric motor as a power source for traveling. Alternatively, it is a hybrid automobile that can appropriately select and use an electric motor or an engine as a power source for traveling. By using one embodiment of the present invention, a vehicle with a long cruising distance can be realized. Furthermore, the automobile 8400 includes a secondary battery. The secondary battery not only drives the electric motor 8406 but also can supply power to a light-emitting device such as a headlight 8401 or a room light (not shown).

[0471] The secondary battery can also supply power to display devices such as a speedometer and a tachometer included in the automobile 8400. The secondary battery can also supply power to semiconductor devices such as a navigation system included in the automobile 8400.

[0472] The automobile 8500 shown in FIG. 25B can charge the secondary battery of the automobile 8500 by receiving power supply from an external charging facility using a plug-in system, a contactless power supply system, or the like. FIG. 25B shows a state in which a secondary battery 8024 mounted on the automobile 8500 is being charged via a cable 8022 from a ground-mounted charging device 8021. The charging device 8021 may be a charging station installed in a commercial facility or a home power source. For example, plug-in technology can be used to charge the secondary battery 8024 mounted on the automobile 8500 using an external power supply. Charging can be performed by converting AC power to DC power using a conversion device such as an AC-DC converter.

[0473] Although not shown, a power receiving device can be mounted on a vehicle and power can be supplied contactlessly from a ground power transmitting device to charge the vehicle. In the case of this contactless power supply method, by incorporating a power transmitting device into a road or an exterior wall, charging can be performed not only while the vehicle is stopped but also while the vehicle is moving. This contactless power supply method can also be used to transmit and receive power between vehicles. Furthermore, a solar cell can be installed on the exterior of the vehicle to charge the secondary battery while the vehicle is stopped or moving. For such contactless power supply, an electromagnetic induction method or a magnetic field resonance method can be used.

[0474] 25C shows an example of a two-wheeled vehicle using the secondary battery of one embodiment of the present invention. A scooter 8600 shown in FIG. 25C includes a secondary battery 8602, a side mirror 8601, and a turn signal light 8603. The secondary battery 8602 can supply electricity to the turn signal light 8603.

[0475] 25C is capable of storing a secondary battery 8602 in under-seat storage 8604. Even if under-seat storage 8604 is small, secondary battery 8602 can be stored in under-seat storage 8604. Secondary battery 8602 is removable, and when charging, secondary battery 8602 can be carried indoors, charged, and then stored before riding.

[0476] When the battery control system according to one embodiment of the present invention is installed in the vehicle, the battery can be used efficiently, and a next-generation clean energy vehicle can be realized.

[0477] This embodiment mode can be implemented in appropriate combination with other embodiment modes.

[0478] 10: Battery control system, 101: Drive battery, 101a: Battery, 101b: Battery, 102: Temperature sensor, 103a: Circuit, 103b: Circuit, 112: BMU, 105: DCDC circuit, 105a: DCDC circuit, 105b: DCDC circuit

Claims

1. a first battery that can be charged and discharged within a first temperature range; a second battery that can be charged and discharged in a second temperature range; a first circuit electrically connected to the first battery, the first circuit having a first transformer; a second circuit electrically connected to the second battery, the second circuit having a second transformer; one or more temperature sensors that detect temperatures of the first battery and the second battery; when the temperature detected by the temperature sensor is equal to or higher than Tr, the first circuit and the second circuit transfer power from the second battery to the first battery; when the temperature detected by the temperature sensor is lower than Tr, the first circuit and the second circuit transfer power from the first battery to the second battery; the upper limit of the first temperature range is higher than the upper limit of the second temperature range; the lower limit of the first temperature range is lower than the upper limit of the second temperature range; the lower limit of the second temperature range is lower than the lower limit of the first temperature range; The Tr is higher than the lower limit of the first temperature range and lower than the upper limit of the second temperature range. Battery control system.

2. a first battery that can be charged and discharged within a first temperature range; a second battery that can be charged and discharged in a second temperature range; a first circuit having a first transformer electrically connected to an input side of the first battery; a second circuit having a second transformer electrically connected to an input side of the second battery; a first DCDC circuit electrically connected to an output side of the first battery; a second DCDC circuit electrically connected to an output side of the second battery; one or more temperature sensors that detect temperatures of the first battery and the second battery; When the temperature detected by the temperature sensor is equal to or higher than Tr, the first DCDC circuit makes the output from the first battery larger than the output from the second battery; When the temperature detected by the temperature sensor is lower than Tr, the second DCDC circuit makes the output from the second battery larger than the output from the first battery; when the temperature detected by the temperature sensor is equal to or higher than Tr, the first circuit and the second circuit transfer power from the second battery to the first battery; when the temperature detected by the temperature sensor is lower than Tr, the first circuit and the second circuit transfer power from the first battery to the second battery; the upper limit of the first temperature range is higher than the upper limit of the second temperature range; the lower limit of the first temperature range is lower than the upper limit of the second temperature range; the lower limit of the second temperature range is lower than the lower limit of the first temperature range; The Tr is higher than the lower limit of the first temperature range and lower than the upper limit of the second temperature range. Battery control system.

3. In claim 1 or claim 2, The second battery has a discharge capacity value when discharged at the lower limit of the second temperature range that is 50% or more of a discharge capacity value when discharged at 25°C. Battery control system.

4. In claim 1 or claim 2, The first battery is a lithium ion battery and the second battery is a sodium ion battery. Battery control system.

5. In claim 1 or claim 2, the positive electrode active material of the first battery has a layered rock salt crystal structure, and the positive electrode active material of the second battery has an olivine crystal structure; Battery control system.

6. In claim 1 or claim 2, the positive electrode active material of the first battery comprises Li, Ni, Co, and Mn, and the positive electrode active material of the second battery comprises Li, Fe, and phosphorus; Battery control system.

7. In claim 1 or claim 2, the median diameter of the positive electrode active material of the second battery is smaller than the median diameter of the positive electrode active material of the first battery; Battery control system.

8. In claim 1 or claim 2, the electrolyte of the second battery is different from the electrolyte of the first battery; the electrolyte of the second battery includes ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC); When the total content of the ethylene carbonate, the ethyl methyl carbonate, and the dimethyl carbonate is 100 vol%, the volume ratio of the ethylene carbonate, the ethyl methyl carbonate, and the dimethyl carbonate is x:y:100-x-y (where 5≦x≦35 and 0<y<65). Battery control system.