WO2022149393A1

WO2022149393A1 - Power storage element

Info

Publication number: WO2022149393A1
Application number: PCT/JP2021/044939
Authority: WO
Inventors: ハルシユジヤガード; 泰地葛本; 吉一堀越
Original assignee: 株式会社村田製作所
Priority date: 2021-01-06
Filing date: 2021-12-07
Publication date: 2022-07-14

Abstract

This secondary cell comprises a cell element including a first electrode, a second electrode, and a separator, the first electrode and the second electrode being wound via the separator in the cell element. The first electrode and/or the second electrode include a current collector which extends in one direction and has a substantially rectangular notch part in a corner of one end thereof, an active material layer formed on the current collector in a region excluding the exposed region, and a current collection tab provided to the current collector in the exposed region.

Description

Power storage element

This technology relates to a power storage element.

In recent years, electronic devices such as mobile phones, smartphones, and wearable terminals have become widespread. Therefore, the importance of a secondary battery is increasing as a power storage element used as a power source in these electronic devices.

As the performance of electronic devices has improved, it has become necessary to further increase the capacity of secondary batteries. Therefore, in the secondary battery, in addition to the positive electrode, the negative electrode, the separator, and the electrolytic solution, various developments of an electrode body composed of the positive electrode, the negative electrode, and the separator are underway (for example, Patent Documents 1 and 1). 2).

US Patent Application Publication No. 2014/0315061 European Patent Application Publication No. 2793285

In such a secondary battery, it is desired to realize further increase in capacity by increasing the amount of active material held in the battery element.

Therefore, it is desirable to provide a power storage element capable of further increasing the capacity.

The power storage element according to an embodiment of the present technology includes a battery element including a first electrode, a second electrode, and a separator. In the battery element, the first electrode and the second electrode are wound via the separator. At least one of the first electrode or the second electrode extends in one direction and is shorter than the length of the current collector having a substantially rectangular notch at one end and the notch in one direction from one end. It includes an exposed region provided in the range, an active material layer formed in the current collector in the region excluding the exposed region, and a current collector tab provided in the current collector in the exposed region.

According to the power storage element according to the embodiment of the present technology, in the battery element, the first electrode and the second electrode are wound via a separator, and at least one of the first electrode and the second electrode is one end. For a current collector having a substantially rectangular notch at the corner of the above, an exposed area provided in a range shorter than the length in the longitudinal direction in which the notch is provided, and a current collector in an area excluding the exposed area. Includes the formed active material layer. Therefore, it is possible to realize a higher capacity.

The effect of this technique is not necessarily limited to the effect described here, and may be any of a series of effects related to this technique described later.

It is a schematic vertical sectional view which shows the sectional structure of the secondary battery which is an example of the power storage element which concerns on one Embodiment of this technique. It is a schematic plan view which shows the structure of the electrode provided in the secondary battery which concerns on the same embodiment. It is a schematic plan view which shows the structure of the electrode provided in the secondary battery which concerns on a comparative example. It is a schematic plan view explaining the dimension of each part of the electrode in the secondary battery which concerns on the same embodiment. It is a block diagram which shows the structure of the battery pack which is an example of the application example of the secondary battery which concerns on the same embodiment.

Hereinafter, one embodiment of the present technology will be described in detail with reference to the drawings. The order of explanation is as follows.

1. 1. Power storage element 1-1. Configuration 1-2. Operation 1-3. Manufacturing method 1-4. Action and effect 2. Applications of power storage elements

<1. Power storage element>
First, with reference to FIG. 1, a power storage element according to an embodiment of the present technology will be described.

The type of power storage element is not particularly limited, but specifically, it is an electrochemical device such as a battery or a capacitor. This battery may be a primary battery or a secondary battery. Hereinafter, a secondary battery, which is an example of a power storage element, will be described.

The secondary battery described here is a secondary battery that obtains a battery capacity by utilizing the occlusion and release of an electrode reactant, and includes a positive electrode, a negative electrode, and an electrolytic solution. In the secondary battery, the charge capacity of the negative electrode is larger than the discharge capacity of the positive electrode in order to prevent the electrode reactant from precipitating on the surface of the negative electrode during charging. That is, the electrochemical capacity per unit area of the negative electrode is larger than the electrochemical capacity per unit area of the positive electrode.

The electrode reactant is not particularly limited, but is a light metal such as an alkali metal and an alkaline earth metal. Alkali metals include lithium, sodium and potassium. Alkaline earth metals include beryllium, magnesium and calcium.

In the following, the case where the electrode reactant is lithium will be taken as an example. A secondary battery that obtains battery capacity by utilizing the occlusion and release of lithium is a so-called lithium ion secondary battery. In a lithium-ion secondary battery, lithium is occluded and released in an ionic state.

<1-1. Configuration>
[overall structure]
FIG. 1 is a schematic vertical sectional view showing a sectional configuration of a secondary battery according to the present embodiment. As shown in FIG. 1, the secondary battery includes a battery element 10, a container member 11, a lid member 12, and a tab terminal 13.

The container member 11 is an accommodating member having a vessel-like structure for accommodating the battery element 10. Specifically, the container member 11 has a structure in which the side wall is upright from the outer edge of the bottom surface to the entire circumference and the upper surface facing the bottom surface is open. That is, the container member 11 has a concave cross-sectional shape. The shape of the bottom surface of the container member 11 may be circular, elliptical, semi-circular or fan-shaped by cutting out a part of the circular shape, or polygonal.

The lid member 12 is an accommodating member having a vessel-like structure attached to the opening of the container member 11. Specifically, the lid member 12 has a structure in which a side wall is provided on the outer edge of the bottom surface over the entire circumference, and the upper surface facing the bottom surface is open. That is, the container member 11 has a concave cross-sectional shape whose height is lower than that of the container member 11.

By attaching the lid member 12 to the container member 11 so that the openings face each other, it is possible to form a space in which the battery element 10 is housed inside the container member 11 and the lid member 12. The container member 11 and the lid member 12 may be coupled to each other by using at least one of gaskets, adhesives, or caulking structures.

Specifically, the bottom surface of the lid member 12 is provided so as to have a similar shape to the bottom surface of the container member 11 and to be larger than the bottom surface of the container member 11. According to this, the lid member 12 can be fitted to the container member 11 while facing each other's openings to form a space in which the battery element 10 can be accommodated inside the container member 11 and the lid member 12. can.

The three-dimensional shape defined by the container member 11 and the lid member 12 described above is a columnar three-dimensional shape, and more specifically, a flat and columnar three-dimensional shape. The flat and columnar three-dimensional shape has a pair of bottoms facing each other substantially parallel to each other and a side wall connecting the pair of bottoms, and the distance (that is, height) between the bottoms with respect to the outer diameter of the bottoms. It is a small three-dimensional shape. The secondary battery according to the present embodiment may be a so-called coin-type secondary battery having a flat cylindrical shape, a button-type secondary battery, or the like.

The tab terminal 13 is a first terminal that protrudes outward from the inside of the lid member 12 and is provided in the center of the lid member 12 and is connected to either the positive electrode or the negative electrode of the battery element 10. The tab terminal 13 is made of a material having electrical conductivity such as a metal material. Specifically, the tab terminal 13 may function as a positive electrode terminal by being connected to the positive electrode of the battery element 10, and the container member 11 may function as a negative electrode terminal by being connected to the negative electrode of the battery element 10. good. The tab terminal 13 and the container member 11 can each function as a positive electrode terminal or a negative electrode terminal by being electrically insulated from each other by an organic insulator such as a gasket or an adhesive.

Each of the container member 11, the lid member 12, and the tab terminal 13 described above is a Fe—Cr or Fe—Cr—Ni stainless steel material having good corrosion resistance (for example, in the JIS standard). It may be composed of a stainless steel material such as the symbol SUS304, SUS305, or SUS430).

However, in the container member 11, the lid member 12, and the tab terminal 13 connected to the positive electrode having a positive electrode unipolar potential exceeding 4.0 V in the charged state, ions such as iron, chromium, or nickel from the stainless steel material are electrolytic solutions. Elution into it can reduce the corrosion resistance of stainless steel. Therefore, the surface of the container member 11, the lid member 12, or the tab terminal 13 connected to the positive electrode facing the battery element 10 may be made of a metal such as aluminum, which is unlikely to deteriorate in corrosion resistance due to a high potential. preferable. Specifically, the container member 11, the lid member 12, or the tab terminal 13 may be made of a material in which aluminum is laminated or vapor-deposited on one surface of stainless steel, or is made of a clad material in which stainless steel and aluminum are joined. May be done. Further, the container member 11, the lid member 12, or the tab terminal 13 may be made of only aluminum.

The battery element 10 is a main element of a secondary battery that performs a charge / discharge reaction, and includes a positive electrode, a negative electrode, and a separator. Although details are not shown, the battery element 10 is an electrode body in which a positive electrode and a negative electrode face each other via a separator, and the positive electrode, the negative electrode, and the separator are impregnated with an electrolytic solution. Specifically, the electrode body is a wound type electrode body in which the laminated separator, the positive electrode, and the negative electrode are wound around the height direction of the container member 11 and the lid member 12 in the axial direction. The number of turns of each of the separator, the positive electrode, and the negative electrode is arbitrary and is not particularly limited.

The positive electrode is one of the electrodes constituting the battery element 10. The positive electrode includes a positive electrode current collector, a positive electrode active material layer formed on both sides or one side of the positive electrode current collector, and a positive electrode tab bonded to the positive electrode current collector.

The positive electrode current collector is a metal leaf containing a metal material such as aluminum. The positive electrode current collector may be composed of a long-shaped foil extending in one direction.

The positive electrode active material layer contains a positive electrode active material that occludes and releases lithium, and is provided on both sides or one side of the positive electrode current collector. The positive electrode active material contains any one or more of lithium-containing compounds such as lithium-containing transition metal compounds. The lithium-containing transition metal compound is an oxide, a phosphoric acid compound, a silicic acid compound, a boric acid compound or the like containing one or more kinds of transition metal elements as constituent elements together with lithium. The positive electrode active material layer may further contain a positive electrode binder, a positive electrode conductive agent, and the like.

The positive electrode tab contains the same metal material or a different metal material as the positive electrode current collector, and is provided at the end of the longitudinal shape of the positive electrode current collector in the extending direction. One end of the positive electrode tab is joined to the positive electrode current collector, and the other end is joined to the tab terminal 13, so that electric charges can be taken out from the positive electrode current collector.

The negative electrode is the other electrode constituting the battery element 10. Like the positive electrode, the negative electrode includes a negative electrode current collector, a negative electrode active material layer formed on both sides or one side of the negative electrode current collector, and a negative electrode tab bonded to the negative electrode current collector.

The negative electrode current collector is a metal leaf containing a metal material such as copper. Like the positive electrode current collector, the negative electrode current collector may be composed of a long-shaped foil extending in one direction.

The negative electrode active material layer contains a negative electrode active material that occludes and releases lithium, and is provided on both sides or one side of the negative electrode current collector. The negative electrode active material includes any one or more of carbon materials and metal-based materials. The carbon material is graphite or the like. The metal-based material is a material containing one or more of metal elements and metalloid elements capable of forming an alloy with lithium as constituent elements, and specifically includes silicon, tin, and the like. It is a material. The metal-based material may be a simple substance, an alloy, a compound, or a mixture of two or more thereof. The negative electrode active material layer may further contain a negative electrode binder, a negative electrode conductive agent, and the like.

Like the positive electrode tab, the negative electrode tab contains the same metal material or a different metal material as the negative electrode current collector, and is provided at the end of the longitudinal shape of the negative electrode current collector in the extending direction. One end of the negative electrode tab is joined to the negative electrode current collector, and the other end is joined to the container member 11, so that electric charges can be taken out from the negative electrode current collector.

The separator is an insulating porous film interposed between the positive electrode and the negative electrode. The separator can allow lithium to pass through while preventing a short circuit between the positive electrode and the negative electrode. The separator may contain any one or more of the polymer materials such as polyethylene.

The electrolytic solution is impregnated in each of the positive electrode, the negative electrode and the separator, and contains a solvent and an electrolyte salt. The solvent includes any one or more of non-aqueous solvents (organic solvents) such as carbonic acid ester-based compounds, carboxylic acid ester-based compounds and lactone-based compounds. The electrolyte salt contains any one or more of light metal salts such as lithium salts.

[Detailed configuration of electrodes]
Subsequently, with reference to FIGS. 2 and 3, the configuration of the electrodes in the secondary battery according to the present embodiment will be described in more detail. FIG. 2 is a schematic plan view showing the configuration of electrodes included in the secondary battery according to the present embodiment. FIG. 3 is a schematic plan view showing the configuration of the electrodes included in the secondary battery according to the comparative example.

In the present embodiment, both the positive electrode and the negative electrode may have the configuration described below, or only one of the positive electrode or the negative electrode may have the configuration described below. However, in order to more effectively obtain the effect of increasing the capacity of the secondary battery by the present technology, it is preferable that both the positive electrode and the negative electrode have the configurations described below.

As shown in FIG. 2, the electrodes 20 included in the secondary battery include a current collector 21, an active material layer 22 formed on both sides or one side of the current collector 21, and one end of the current collector 21 on the E1 side. It is provided with a current collecting tab 23 joined to the portion. The electrode 20 is wound so that one end E1 side is inside the winding, and the lid member 12 is present in the upward direction facing FIG. 2, and the container member 11 is in the downward direction facing FIG. Is housed inside the secondary battery so that it is present.

The current collector 21 is a metal foil containing the above-mentioned metal material. The current collector 21 has a longitudinal shape extending in one direction, and has a notch 21D having a substantially rectangular shape at one corner of E1 in the extending direction. One end E1 side of the current collector 21 is the winding inside of the battery element 10 which is a winding type electrode body, and one end E1 side of the current collector 21 is a tab terminal 13 provided in the substantially center of the lid member 12. A notch 21D is provided in order to avoid a short circuit between the current collector 21 and the current collector 21. By providing the notch 21D, the central portion inside the winding of the battery element 10 can be recessed, so that the battery element 10 secures a clearance for the tab terminal 13 which is convex in the internal space of the secondary battery. can do.

The active material layer 22 is a layer containing the above-mentioned positive electrode active material or negative electrode active material, and is formed on one side or both sides of the current collector 21 excluding the exposed region 21C provided on one end E1 side of the current collector 21. .. The exposed region 21C is provided for joining the current collector tab 23 to the current collector 21 by a welding method. The current collector tab 23 is directly welded to the current collector 21 in the exposed region 21C, so that the joint strength between the current collector 21 and the current collector tab 23 can be further increased.

The current collector tab 23 contains the same metal material or a different metal material as the current collector 21 as described above. One end of the current collector tab 23 is joined to the exposed region 21C at one end of the current collector 21 on the E1 side, and the other end of the current collector tab 23 is connected to the tab terminal 13 or the container member 11.

Here, of the current collector 21 having a longitudinal shape, the region where the length of the current collector 21 in the lateral direction is shortened by the notch 21D is defined as the notch region 21B, and the notch 21D makes the current collector 21 of the current collector 21. The region where the length in the lateral direction is not shortened is referred to as the main region 21A. In the secondary battery according to the present embodiment, the active material layer 22 is provided not only in the main region 21A but also in the region other than the exposed region 21C of the notch region 21B. At this time, the exposed region 21C is provided in a range shorter than the length provided with the notch 21D from one end E1 of the current collector 21. According to this, in the secondary battery according to the present embodiment, the area of the active material layer 22 formed on the current collector 21 can be made larger, so that the capacity can be further increased. Is.

On the other hand, in the electrode 200 included in the secondary battery according to the comparative example, as shown in FIG. 3, the active material layer 22 is provided only in the main region 21A of the current collector 21. In the secondary battery according to the comparative example, since the active material layer 22 is not formed in the entire notch region 21B, it is easy to grasp the region where the active material layer 22 is not formed, and the region where the active material layer 22 of the current collector 21 is not formed. The current collector tab 23 can be joined more easily. Further, in the secondary battery according to the comparative example, when the electrode 200 is wound as the battery element 10, the active material layer 22 is not provided in the notch region 21B existing directly under the tab terminal 13, so that the active material layer 22 and the secondary battery The possibility of a short circuit with the tab terminal 13 can be further reduced. However, in the secondary battery according to the comparative example, the active material layer 22 is not formed on the current collector 21 in the notch region 21B, and the electrode 200 has many regions that do not contribute to the capacity of the secondary battery. It is difficult to increase the capacity of the battery.

In the secondary battery according to the present embodiment, the region where the active material layer 22 is not formed on the current collector 21 can be limited to the exposed region 21C, which is a narrower region than the notch region 21B. Therefore, the current collector 21 can be used. The area of the active material layer 22 formed on the top can be increased. Therefore, the secondary battery according to the present embodiment can realize a higher capacity.

<1-2. Operation>
The secondary battery according to this embodiment can perform charge / discharge operation as follows.

In the secondary battery during charging, lithium ions are released from the positive electrode and lithium ions are stored in the negative electrode via the electrolytic solution. On the other hand, in the secondary battery at the time of discharge, lithium ions are released from the negative electrode and lithium ions are stored in the positive electrode via the electrolytic solution. That is, in the secondary battery, lithium ions can be charged and discharged by moving between the positive electrode and the negative electrode via the electrolytic solution.

<1-3. Manufacturing method>
Next, a method for manufacturing the secondary battery will be described. The secondary battery is manufactured by manufacturing a positive electrode and a negative electrode in the process described below, and then assembling each configuration including the positive electrode and the negative electrode.

[Preparation of positive electrode]
First, a positive electrode mixture is formed by mixing a positive electrode active material with a binder and a conductive material, if necessary. Next, a paste-like positive electrode mixture slurry is prepared by dispersing or dissolving the positive electrode mixture in water or an organic solvent. Subsequently, a positive electrode mixture slurry is applied to predetermined regions on both sides of the positive electrode current collector and then dried to produce a positive electrode having positive electrode active material layers formed on both sides of the positive electrode current collector. .. The positive electrode active material layer may be compression-molded using a roll press machine or the like. The compression molding may be performed while heating, or may be repeated a plurality of times.

[Manufacturing of negative electrode]
The negative electrode can be manufactured by the same method as the above-mentioned method for manufacturing the positive electrode. Specifically, first, the negative electrode active material is mixed with a binder and a conductive material, if necessary, to form a negative electrode mixture. Next, a paste-like negative electrode mixture slurry is prepared by dispersing or dissolving the negative electrode mixture in water or an organic solvent. Subsequently, a negative electrode mixture slurry is applied to predetermined regions on both sides of the negative electrode current collector and then dried to produce a negative electrode having negative electrode active material layers formed on both sides of the negative electrode current collector. .. The negative electrode active material layer may be compression-molded using a roll press machine or the like. The compression molding may be performed while heating, or may be repeated a plurality of times.

[Assembly of secondary battery]
First, the positive electrode tab is connected to the positive electrode and the negative electrode tab is connected to the negative electrode by using a welding method or the like. Next, after the positive electrode and the negative electrode are opposed to each other via the separator, the positive electrode, the negative electrode, and the separator are wound to form a wound electrode body.

Subsequently, the electrode body is housed inside the container member 11. At this time, the negative electrode tab is connected to the container member 11 by using a welding method or the like. Next, the electrolytic solution is impregnated into the electrode body by injecting the electrolytic solution into the inside of the container member 11. As a result, the electrolytic solution impregnates into each of the positive electrode, the negative electrode, and the separator, and the battery element 10 is formed.

After that, the lid member 12 to which the tab terminal 13 is attached is fitted to the container member 11. As a result, the space formed by the container member 11 and the lid member 12 is sealed. At this time, the positive electrode tab is connected to the tab terminal 13 by using a welding method or the like. By the above steps, the secondary battery according to the present embodiment can be manufactured.

<1-4. Actions and effects>
In the secondary battery which is the power storage element according to the present embodiment, the notch 21D is formed in the current collector 21 for the clearance with the tab terminal 13, and the notch 21D forms the length of the current collector 21 in the lateral direction. The active material layer 22 is formed in a part of the notch region 21B in which is shortened. Further, the cutout region 21B is provided with an exposed region 21C in which the active material layer 22 is not formed at one end E1 of the current collector 21, and the current collector tab 23 is joined to the exposed region 21C. According to this, in the secondary battery according to the present embodiment, the area of the active material layer 22 formed on the current collector 21 can be made larger, so that the utilization efficiency of the internal space of the secondary battery can be improved. It is possible to improve and realize a higher capacity.

[Estimation of effect]
Next, with reference to FIG. 4, an example of estimating the area increasing effect of the active material layer 22 of the electrode 20 in the secondary battery according to the present embodiment will be described. FIG. 4 is a schematic plan view illustrating the dimensions of each part of the electrode 20 in the secondary battery according to the present embodiment.

As shown in FIG. 4, in the electrode 20, the length (width) of the current collector 21 in the lateral direction is We, and the length (width) of the notch 21D in the lateral direction is Wd. Further, the length in the longitudinal direction of the region (that is, the main region 21A) of the current collector 21 in which the notch portion 21D is not provided is set to Le, and the region of the notch region 21B excluding the exposed region 21C (that is, the notch region). The length in the longitudinal direction of 21B (the region where the active material layer 22 is formed) is defined as Ld. According to this, the area Se of the active material layer 22 formed in the main region 21A can be expressed as the product of We and Le. Further, the area Sd of the active material layer 22 formed in the notch region 21B can be expressed as the product of (We—Wd) and Ld.

Here, the active material layer 22 when the length in the longitudinal direction of the region (that is, the main region 21A) of the current collector 21 in which the notch 21D is not provided is changed with reference to the 1654 size secondary battery. The estimated area of is shown in Table 1 below. The inner diameter of the tab terminal 13 in the 1654 size secondary battery is 2.7 mm, and the height is 0.15 mm.

According to the results shown in Table 1, it can be seen that the smaller the length of the main region 21A (that is, the length of the electrode 20), the greater the effect of increasing the area of the active material layer 22 by this technique. Further, even when the safety factor of the short circuit between the tab terminal 13 and the electrode 20 is estimated to be 1.5 times, the increase rate of the area of the active material layer 22 by the present technique can be set to 2% or more.

Next, the area of the active material layer 22 when the height of the secondary battery is changed (that is, when the width of the current collector 21 is changed) is estimated below with reference to the 1654 size secondary battery. It is shown in Table 2 of. The inner diameter of the tab terminal 13 in the 1654 size secondary battery is 2.7 mm, and the height is 0.15 mm.

According to the results shown in Table 2, it can be seen that the effect of increasing the area of the active material layer 22 by this technique can be obtained regardless of the change in the width of the current collector 21.

Subsequently, both the longitudinal length of the area of the current collector 21 without the notch 21D (ie, the main area 21A) and the width of the current collector 21 with respect to the 1654 size secondary battery. The estimation of the area of the active material layer 22 when each of the above is changed is shown in Table 3 below. The inner diameter of the tab terminal 13 in the 1654 size secondary battery is 2.7 mm, and the height is 0.15 mm.

According to the results shown in Table 3, it can be seen that the smaller the length of the main region 21A (that is, the length of the electrode 20), the greater the effect of increasing the area of the active material layer 22 by this technique. On the other hand, according to the results shown in Table 3, it can be seen that the effect of increasing the area of the active material layer 22 by the present technique can be obtained regardless of the change in the width of the current collector 21.

Subsequently, with reference to the 1654 size secondary battery, the length in the longitudinal direction of the region of the notch region 21B excluding the exposed region 21C (that is, the region of the notch region 21B where the active material layer 22 is formed). The estimation of the area of the active material layer 22 when the above is changed is shown in Table 4 below. The inner diameter of the tab terminal 13 in the 1654 size secondary battery is 2.7 mm, and the height is 0.15 mm.

According to the results shown in Table 4, it can be seen that the larger the length of the notched region 21B excluding the exposed region 21C, the greater the effect of increasing the area of the active material layer 22 by this technique.

<2. Applications of power storage elements>
Here, an application of a secondary battery, which is an example of a power storage element, will be described. The application (application example) of the secondary battery is not particularly limited. The secondary battery used as a power source may be used as a main power source for electronic devices and electric vehicles, or may be used as an auxiliary power source. The main power source is a power source that is preferentially used regardless of the presence or absence of another power source, and the auxiliary power source is a power source that is used in place of the main power source or a power source that can be switched from the main power source.

Specific examples of applications for secondary batteries include video cameras, digital still cameras, mobile phones, laptop computers, headphone stereos, electronic devices such as portable radios and portable information terminals, and storage devices such as backup power supplies and memory cards. , Electric tools such as electric drills and saws, battery packs mounted on electronic devices, medical electronic devices such as pacemakers and hearing aids, electric vehicles such as electric vehicles (including hybrid vehicles), and in emergencies. It is a power storage system such as a household or industrial battery system that stores power in preparation for it. In these applications, one secondary battery may be used, or a plurality of secondary batteries may be used.

The battery pack may be configured by using a single battery or may be configured by using an assembled battery. The electric vehicle is a vehicle that operates (runs) using a secondary battery as a driving power source, and may be a hybrid vehicle that also includes a driving source other than the secondary battery. The household electric power storage system can operate household electric products and the like by using the electric power stored in the secondary battery which is the electric power storage source.

Here, an example of application of the secondary battery will be specifically described. The configuration of the application example described below is just an example, and can be changed as appropriate.

FIG. 5 shows the block configuration of the battery pack. The battery pack described here is a battery pack (so-called soft pack) using one secondary battery, and is mounted on an electronic device represented by a smartphone.

As shown in FIG. 5, the battery pack includes a power supply 410 and a circuit board 420. The circuit board 420 is connected to the power supply 410 and includes a positive electrode terminal 210, a negative electrode terminal 310, and a temperature detection terminal 430.

The power supply 410 includes one secondary battery. In the secondary battery, the positive electrode lead is connected to the positive electrode terminal 210, and the negative electrode lead is connected to the negative electrode terminal 310. The power supply 410 can be connected to the outside via the positive electrode terminal 210 and the negative electrode terminal 310, and can be charged and discharged via the positive electrode terminal 210 and the negative electrode terminal 310. The circuit board 420 includes a control unit 440, a switch 450, a PTC element 460, and a temperature detection unit 470. However, the PTC element 460 may be omitted.

The control unit 440 includes a central processing unit (CPU: Central Processing Unit), a memory, and the like, and controls the operation of the entire battery pack. The control unit 440 detects and controls the usage state of the power supply 410 as needed.

When the voltage of the power supply 410 (secondary battery) reaches the overcharge detection voltage or the overdischarge detection voltage, the control unit 440 cuts off the switch 450 so that the charging current does not flow in the current path of the power supply 410. Can be done. The overcharge detection voltage and the overdischarge detection voltage are not particularly limited. As an example, the overcharge detection voltage is 4.2V ± 0.05V, and the overdischarge detection voltage is 2.4V ± 0.1V.

The switch 450 includes a charge control switch, a discharge control switch, a charging diode, a discharging diode, and the like, and switches whether or not the power supply 410 is connected to an external device according to an instruction from the control unit 440. The switch 450 includes a metal-oxide-semiconductor field-effect transistor (MOSFET: Metal-Oxide-Semiconductor Dutor Field-Effective Transistor) and the like. The charge / discharge current is detected based on the ON resistance of the switch 450.

The temperature detection unit 470 includes a temperature detection element such as a thermistor, measures the temperature of the power supply 410 using the temperature detection terminal 430, and outputs the temperature measurement result to the control unit 440. The temperature measurement result measured by the temperature detection unit 470 is that the control unit 440 performs charge / discharge control of the power supply 410 when abnormal heat generation occurs, and the control unit 440 corrects the remaining capacity of the power supply 410 when calculating the remaining capacity. It is used when doing so.

Although the present technique has been described above with reference to one embodiment and examples, the configuration of the technique is not limited to the configuration described in one embodiment and examples, and thus can be variously modified.

In the above, the case where the electrode reactant is lithium has been described, but the electrode reactant is not particularly limited. Specifically, as described above, the electrode reactant may be another alkali metal such as sodium and potassium, or an alkaline earth metal such as beryllium, magnesium and calcium. In addition, the electrode reactant may be another light metal such as aluminum.

Further, in the above embodiment, the separator is described as being a porous membrane, but the configuration of the separator is not particularly limited. The separator may be a laminated film containing a polymer compound layer.

Specifically, the separator may include a base material layer which is the above-mentioned porous film and a polymer compound layer provided on one side or both sides of the base material layer. The polymer compound layer contains a polymer compound such as polyvinylidene fluoride, which has excellent physical strength and is electrochemically stable. According to this, since the separator can improve the adhesion to each of the positive electrode and the negative electrode, it is possible to suppress the positional deviation inside the battery element 10. Therefore, a power storage element such as a secondary battery can suppress the occurrence of swelling even when a decomposition reaction of the electrolytic solution occurs.

Note that one or both of the base material layer and the polymer compound layer may contain a plurality of particles. The plurality of types of particles may be any one or more than one of particles such as inorganic particles and resin particles. According to this, since the power storage element such as a secondary battery can dissipate heat with a plurality of particles at the time of heat generation, heat resistance and safety can be improved. The inorganic particles are not particularly limited, but are particles such as aluminum oxide (alumina), aluminum nitride, boehmite, silicon oxide (silica), titanium oxide (titania), magnesium oxide (magnesia) and zirconium oxide (zirconia).

Further, in the above embodiment, the electrolyte is described as a liquid electrolyte, but the electrolyte is not limited to the liquid. The electrolyte may be a gel-like electrolyte layer.

In the battery element 10 using the gel-like electrolyte layer, the positive electrode and the negative electrode are laminated with each other via the separator and the electrolyte layer, and then the positive electrode, the negative electrode, the separator and the electrolyte layer are wound. According to this, the electrolyte layer is interposed between the positive electrode and the separator and is interposed between the negative electrode and the separator. The electrolyte layer contains a polymer compound such as polyvinylidene fluoride together with the electrolytic solution, and the electrolytic solution can be held by the polymer compound. The structure of the electrolytic solution is as described above. Even in such an electrolyte layer, lithium can be transferred between the positive electrode and the negative electrode.

Since the effects described in the present specification are merely examples, the effects of the present technology are not limited to the effects described in the present specification. Therefore, other effects may be obtained with respect to this technique.

Claims

A battery element including a first electrode, a second electrode and a separator is provided.
In the battery element, the first electrode and the second electrode are wound around the separator.
At least one of the first electrode or the second electrode
A current collector that extends in one direction and has a substantially rectangular notch at one end.
An exposed area provided in a range shorter than the length of the notch in the one direction from the one end.
The active material layer formed on the current collector in the region excluding the exposed region,
A power storage element including a current collector tab provided on the current collector in the exposed area.
The one end is one end of the winding inside of the battery element.
The power storage element according to claim 1.
moreover,
A columnar container-shaped member having an opening on one surface and accommodating the battery element,
A lid-like member that covers the opening and is attached to the vessel-like member.
The power storage element according to claim 1 or 2.
The first electrode and the second electrode include the current collector, the exposed region, the active material layer, and the current collector tab, respectively.
The power storage element according to claim 3.
The current collecting tab of either the first electrode or the second electrode is connected to a tab terminal provided in the center of the lid-shaped member.
The power storage element according to claim 4.
The current collecting tab of any one of the first electrode and the second electrode is connected to the vessel-shaped member.
The power storage element according to claim 5.
Lithium-ion secondary battery,
The power storage element according to any one of claims 1 to 6.