JP2013225410A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit the deposition of dendrite regardless of type of an electrode material in a secondary battery.SOLUTION: A secondary battery includes: a first electrode 1; and a second electrode 2 that is disposed facing the first electrode 1 and has a surface area larger than a facing surface of the first electrode 1. Further, an electrolytic solution 4 including at least metal ions is disposed between the first electrode 1 and the second electrode 2. Further, the secondary battery includes position change means 7,9 changing a position of a facing surface of the second electrode 2 relative to the first electrode 1.

Description

  The present invention relates to a secondary battery having at least a pair of electrodes.

  Conventionally, various types of secondary batteries have been used as power sources for driving cellular phones and cordless power tools. Alkaline secondary batteries using alkaline electrolyte and lead acid batteries using dilute sulfuric acid electrolyte Are widely known. In recent years, lithium-ion secondary batteries having features such as large capacity and high output have been introduced into the market, and the market scale is expanding. Lithium ion secondary batteries are used not only as portable electric products but also as power supply devices for electric vehicles, hybrid vehicles, emergency power supply facilities, and the like.

  In a general lithium ion secondary battery, a ceramic material such as lithium cobaltate or lithium nickelate is used for the positive electrode, and a carbon-based material such as graphite or amorphous carbon is used for the negative electrode. The carbon-based material of the negative electrode has a layered crystal structure and functions as an intercalation electrode that holds lithium ions ionized at the positive electrode between the layers. By using such a negative electrode, deposition of lithium metal on the electrode surface is suppressed.

  However, even when a negative electrode made of a carbon-based material is used, lithium metal may be deposited on a part of the negative electrode surface due to a bias in current density or lithium ion concentration, and dendrite may grow from that site. As a result, a short circuit between the electrodes may occur, and the battery capacity may be reduced due to a lack of active material.

  In order to solve such a problem, a technique for suppressing the precipitation of dendrite by making the utilization factor of the active material on the electrode surface (contribution rate of the active material to the battery reaction) uniform has been proposed. For example, Patent Document 1 describes a secondary battery in which a current collector is exposed in a groove shape on the surface of a positive electrode or a negative electrode. In this technique, a masking tape is radially attached to the surface of a current collector of an electrode on which an active material layer is formed, and the current collector is exposed by peeling the masking tape after the active material layer is formed. Thus, it is said that reducing the amount of active material at a site where dendrite is likely to occur can make the utilization rate of the active material uniform and make it difficult to deposit metal.

JP 2003-151534 A

  However, the conventional technique for changing the distribution of the amount of active material can only average the active material utilization rate that is different for each part, and cannot reduce the active material utilization rate in the entire electrode. Therefore, for example, at the time of rapid charging in which a large current is applied between the electrodes in a short time, the active material utilization rate increases on the entire electrode surface, and the generation of dendrites cannot be suppressed.

  Further, in the conventional lithium ion secondary battery, a carbon-based material is mainly used as the negative electrode active material. If zinc or lithium, which is a negative electrode active material of a general primary battery, can be used instead of this carbon-based material, the capacity density of the electrode can be increased, and the performance of the battery can be improved. is there. On the other hand, dendrite is more likely to be generated on the surface of these zinc and lithium than on the surface of the carbon-based material, and there is a problem that practical application is difficult.

  One of the objects of the present invention has been developed in view of the above-described problems, and is to provide a secondary battery that can suppress the generation of dendrite regardless of the type of electrode material. It should be noted that the present invention is not limited to this purpose, and is a function and effect derived from each configuration shown in the embodiment for carrying out the invention described later, and can also provide a function and effect that cannot be obtained by conventional techniques. Can be positioned as

(1) The secondary battery disclosed herein includes a first electrode and a second electrode that is disposed to face the first electrode and has a larger surface area than the facing surface of the first electrode. Moreover, it is arrange | positioned between said 1st electrode and said 2nd electrode, and is equipped with the electrolyte solution containing a metal ion at least. Furthermore, the position change means which changes the position of the opposing surface of said 2nd electrode with respect to said 1st electrode is provided.
In addition, it is preferable that the said secondary battery is equipped with the container which accommodates said 1st electrode, said 2nd electrode, and said electrolyte solution inside. The position changing means preferably changes a relative position of each of the facing surfaces of the first electrode and the second electrode, and at least one of the first electrode and the second electrode is changed. Preferably, it is driven manually or automatically. Here, if the opposing surface on the first electrode side is referred to as a first opposing surface, and the opposing surface on the second electrode side is referred to as a second opposing surface, the position changing means includes the first opposing surface or the first opposing surface. It is preferable to move the position of the two opposing surfaces.

(2) Moreover, it is preferable to provide an estimation means for estimating the generation of dendrites due to the reduction of the metal ions. In this case, it is preferable that the position changing unit changes the position of the facing surface of the second electrode based on the estimation result of the estimating unit.
It is preferable that the estimation means estimate the possibility of occurrence of dendrites (for example, the possibility of generation of dendrites that have not yet occurred or the possibility of growth of dendrites that have already occurred). Alternatively, it is preferable to estimate the generation amount of dendrite (for example, the estimated generation amount estimated to occur in the future, the actual generation amount of dendrite that has already been generated, etc.).
Moreover, it is preferable that the position of the opposing surface of the second electrode is appropriately changed when dendrites are generated as a result of estimation by the estimation means. In this case, for example, it is conceivable to move the position of the first facing surface or the second facing surface for each segment. Alternatively, when there is a possibility that dendrite may occur as a result of estimation by the estimation means, it is preferable to change the position of the facing surface of the second electrode as appropriate. In this case, it is conceivable to continuously move the position of the first facing surface or the second facing surface continuously.

(3) Moreover, it is preferable that the said estimation means estimates generation | occurrence | production of the said dendrite based on a charging / discharging state. The charge / discharge state here includes, for example, states such as a current value and a voltage value related to charge / discharge, a temperature of the electrolytic solution, and a charge capacity.
For example, it is preferable to estimate that the possibility of dendrite generation is high as the current value is large, and that the possibility of dendrite generation is low as the current value is small. For example, it is preferable that the moving speed is decreased as the temperature is higher, and the moving speed is increased as the temperature is lower. For example, it is preferable that the moving speed is decreased as the charging capacity is increased, and the moving speed is increased as the charging capacity is decreased.

(4) Moreover, it is preferable that said 2nd electrode has a some segment area | region on the surface. In this case, it is preferable that a part of each of the segment regions is disposed to face the first electrode. Further, the position changing means is arranged on the first electrode for each segment area based on the generation state of the dendrites obtained by the estimating means (the possibility of occurrence of dendrites, the amount of generated dendrites, etc.). It is preferable to select opposing segment regions.
For example, the second electrode is intermittently driven based on the generation state of the dendrite. For example, when the generation of the dendrite is detected when a certain segmental area is a surface facing the first electrode, the second electrode is arranged so that another segmental area faces the first electrode. Driven.

(5) Further, after the position changing means moves the metal ion or the reduced product of the metal ion containing the dendrite in the electrolyte or to the first electrode, the position of the opposing surface of the second electrode Is preferably changed.
That is, it is preferable that when the facing surface is moved, a metal ion or a reduced product of metal ions including dendrite does not remain on the unused surface. Since the working metal left on the unused surface can no longer be used for electrochemical reactions, the working metal can be desorbed, ionized and decomposed in the electrolyte before moving the opposing surface, or moved to the first electrode. preferable.

(6) Moreover, it is preferable to provide the removal means which scrapes off the dendrite which generate | occur | produced in said 2nd electrode.
(7) Moreover, it is preferable to provide a decomposing means for decomposing the surface layer of the second electrode, and a reproducing means for regenerating the surface layer after decomposing the surface layer by the decomposing means.
(8) Moreover, it is preferable that said 2nd electrode is formed in endless cyclic | annular form.
(9) Alternatively, it is preferable that the second electrode is formed in a belt-like shape whose end is wound around a reel.

  According to the disclosed secondary battery, the surface area of the second electrode is made larger than the facing surface of the first electrode, and the position of the facing surface of the second electrode with respect to the first electrode is changed. The part facing one electrode can be changed. Thereby, the current density on the surface of the second electrode can be reduced, and the active material utilization rate per unit surface area in the second electrode can be reduced.

  Therefore, metal ions ionized in the electrolytic solution can be made difficult to deposit on the surface of the second electrode, and the generation of dendrites can be prevented. Further, even if minute dendrite is generated on the surface of the second electrode, the portion can be moved to a position not facing the first electrode, and dendrite growth can be suppressed. Furthermore, since it becomes difficult to generate dendrite in the second electrode, the range of selection of the electrode material and the active material can be widened, and the performance of the secondary battery can be enhanced.

It is a figure which shows typically the internal structure of the secondary battery which concerns on 1st embodiment, (a) is a side surface and block block diagram, (b) is AA sectional drawing of (a). It is a perspective view which shows typically the structure of the internal peripheral surface of the negative electrode of the secondary battery of FIG. 2 is a graph for explaining the control contents of the secondary battery of FIG. 1, (a) is a graph illustrating the relationship between the current value A and the charge capacity C and the rotation speed V, and (b) is a temperature T and a correction coefficient. It is a graph which illustrates the relationship with K. 2 is a flowchart illustrating a control procedure of the secondary battery in FIG. 1. It is sectional drawing which shows typically the internal structure of the secondary battery which concerns on a modification. It is a figure which shows typically the internal structure of the secondary battery which concerns on a modification, (a) is what formed the shape of the negative electrode in the strip | belt shape, (b) arrange | positions the positive electrode inside the negative electrode. It is a figure which shows typically the internal structure of the secondary battery which concerns on 2nd embodiment, (a) is a side surface and a block block diagram, (b) is BB sectional drawing of (a). It is a perspective view which shows typically the positive electrode and negative electrode of the secondary battery of FIG. It is a graph for demonstrating the control content of the secondary battery of FIG. 7, (a) is a charge curve which shows the change of the charge voltage on constant current conditions, (b) is the discharge voltage on constant current conditions. It is a discharge curve which shows a change. It is a flowchart which illustrates the control procedure of the secondary battery of FIG. It is a figure which shows typically the internal structure of the secondary battery which concerns on 3rd embodiment, (a) is a side surface and a block block diagram, (b) is CC sectional drawing of (a). It is a perspective view which shows typically the positive electrode and negative electrode of the secondary battery of FIG.

  The secondary battery will be described with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment. Each configuration of the present embodiment can be implemented with various modifications without departing from the spirit of the present embodiment, and can be selected or combined as necessary.

[1. First embodiment]
[1-1. Device configuration]
As shown in FIGS. 1A and 1B, the secondary battery 10 of the first embodiment is one in which a positive electrode 1, a negative electrode 2, and an electrolytic solution 4 are accommodated in a metal or resin container 8. The specific composition and material of each of these elements vary depending on the type of the secondary battery 10, but here, lithium ions are transferred between the positive electrode 1 and the negative electrode 2 through the nonaqueous electrolyte solution 4. The case of a lithium ion secondary battery that performs charging / discharging will be described.

The positive electrode 1 (first electrode) is a plate-like electrode in which the positive electrode active material layer 1b is formed on the surface of the positive electrode current collector 1a. The positive electrode current collector 1a is a part connected to the conductive wire via the positive electrode current collector 1d, and is formed of, for example, a plate-like or foil-like metal (such as copper or aluminum).
The positive electrode active material layer 1b is a layered portion including a lithium composite oxide (such as a lithium nickel composite oxide, a lithium cobalt composite oxide, or a lithium manganese composite oxide) that is a positive electrode active material. A conductive material and a binder (binder) are added to the positive electrode active material layer 1b as necessary. As shown in FIG. 1B, the positive electrode active material layer 1b is formed on one surface of the plate-like positive electrode current collector 1a facing the negative electrode 2 side. Hereinafter, the portion of the surface of the positive electrode active material layer 1b that faces the negative electrode 2 is referred to as a first facing surface 1c.

  The negative electrode 2 (second electrode) is an endless annular electrode in which the negative electrode active material layer 2b is formed on the surface of the negative electrode current collector 2a. As shown in FIG. 1B, the negative electrode 2 is formed in a ring shape that is circular in a side view, and is provided so as to be rotatable with respect to the container 8 with the center of the ring as a rotation axis. The negative electrode current collector 2a is a part connected to the conductive wire through the negative electrode current collector 2d, and is formed by joining both ends of a band-shaped metal (such as copper or aluminum). The plate thickness of the negative electrode current collector 2a is a thickness that ensures rigidity sufficient to maintain the circular shape of the negative electrode 2 in a side view. Further, as shown in FIG. 2, a rack 2e forming a rack and pinion type power transmission structure is formed on the inner peripheral surface of the negative electrode current collector 2a in cooperation with a drive gear 7b described later.

  The negative electrode active material layer 2b is a layered portion containing a carbon-based material such as graphite or amorphous carbon, which is a negative electrode active material, and is formed in layers on the outer peripheral side of the surface of the negative electrode current collector 2a. Similarly to the positive electrode active material layer 1b, a conductive material and a binder (binder) are added to the negative electrode active material layer 2b as necessary. Hereinafter, the portion of the surface of the negative electrode active material layer 2b that faces the positive electrode 1 is referred to as a second facing surface 2c.

  The surface area of the negative electrode active material layer 2b is formed larger than the area of the first facing surface 1c. That is, only the second facing surface 2c, which is a part of the entire surface of the negative electrode active material layer 2b, functions as an electrode at a certain moment, and other portions are rested without being used as electrodes ( State of not functioning as an electrode).

  As shown in FIG. 1B, the positive electrode 1 and the negative electrode 2 are disposed so that the positive electrode active material layer 1 b and the negative electrode active material layer 2 b face each other with the separator 3 interposed therebetween in the electrolytic solution 4. The electrolytic solution 4 is, for example, an aprotic solvent (nonaqueous solvent), or a solution obtained by dissolving a lithium compound (supporting electrolyte) such as an inorganic lithium salt or an organic lithium salt in this solvent.

  As shown in FIG. 1A, a charge / discharge circuit is connected between the positive electrode current collector 1d and the negative electrode current collector 2d outside the container 8. The secondary battery 10 is charged according to the charging voltage and charging current given from the charging / discharging circuit, and the electric power in the secondary battery 10 is supplied to the charging / discharging circuit side after charging.

  The separator 3 is a porous film-like member that allows movement of lithium ions in the electrolytic solution 4 while preventing a short circuit due to contact between the positive electrode 1 and the negative electrode 2, and is made of a resin porous material such as polyethylene, polyester, or polypropylene. Quality sheet and non-woven fabric. When the distance between the positive electrode 1 and the negative electrode 2 is sufficiently secured, the separator 3 may be omitted.

  In the vicinity of the outer periphery of the negative electrode 2, a scraper 5 (removing means) is provided for scraping off dendrite that may be deposited on the surface of the negative electrode active material layer 2b. The scraper 5 is a wedge-shaped member made of metal or resin, and is fixed to the container 8 so that the distance between the tip and the negative electrode active material layer 2b is a predetermined distance (for example, several [μm] or more). . This predetermined distance is set to be at least smaller than the distance from the first facing surface 1c to the second facing surface 2c, and in this embodiment, is set to be smaller than the distance from the separator 3 to the second facing surface 2c.

  When the deposition height of the dendrite grown on the surface of the negative electrode active material layer 2b exceeds a predetermined distance, the tip of the scraper 5 comes into contact with the dendrite when the negative electrode 2 rotates, and the dendrite is scraped. Thereby, the deposition height of dendrite is maintained below a predetermined distance.

  Further, the secondary battery 10 incorporates a driving device 7 for changing the position of the negative electrode 2 with respect to the positive electrode 1. This drive device 7 (position changing means) changes the part functioning as an electrode by moving at least one of the opposing surfaces while keeping the opposing distance between the positive electrode 1 and the negative electrode 2 substantially constant. is there.

  The drive device 7 of the present embodiment changes the position of the second facing surface 2c by moving the negative electrode 2. The driving device 7 is provided with a motor 7a, a drive gear 7b, and a tensioner 7c. The entire negative electrode 2 is continuously driven by the driving device 7 so that the position of the second facing surface 2c on the negative electrode active material layer 2b moves. Driven by rotation.

  However, the negative electrode 2 is continuously driven to rotate at least when the secondary battery 10 is charged. At the time of discharging, it may be continuously rotated or rotated as necessary, or the negative electrode 2 is rotated by a necessary rotation angle in order to move the position of the second facing surface 2c. Also good. In this case, the negative electrode 2 may be moved at a speed or timing according to the discharge rate of electric power or the discharge amount so that the portion where the lithium ions are inserted faces the positive electrode 1 in the surface of the negative electrode active material layer 2b.

  For example, the insertion amount of lithium ions and the lithium concentration distribution on the surface of the negative electrode active material layer 2b are recorded in a recording device (not shown), and based on those records, the electrode surface appropriate for the required current value is set as the positive electrode. 1 to face. In addition, it becomes possible to arrange | position an electrode surface rapidly by enabling the negative electrode 2 to rotate to both a normal rotation direction and a reverse rotation direction.

  The motor 7a is an electric motor that rotationally drives the drive gear 7b in response to power supply from a power source (not shown). The rotational speed of the motor 7a is controlled by a control device 9 (position changing means) described later. As shown in FIG. 2, the drive gear 7b is a pinion (gear) that meshes with a rack 2e formed on the inner peripheral surface of the negative electrode 2, and transmits power transmitted from the motor 7a to the negative electrode 2 side. The rotation speed of the negative electrode 2 is proportional to the rotation speed of the motor 7a.

  The tensioner 7c is a roller that applies tension to maintain the annular shape of the negative electrode 2 while supporting the negative electrode 2 from the inner peripheral surface side (negative electrode current collector 2a side). The two tensioners 7c shown in FIG. 1B are provided so as to be movable in the direction of enlarging or reducing the inner diameter of the annular negative electrode 2 with respect to the container 8. The negative electrode 2 is rotationally driven by the motor 7a while the inner side of the negative electrode current collector 2a is supported at three points by the drive gear 7b and the two tensioners 7c.

  A current sensor 11 and a voltage sensor 12 are interposed on the charge / discharge circuit that connects the positive electrode current collector 1d and the negative electrode current collector 2d outside the container 8. The current sensor 11 detects a current value A related to charging / discharging, and the voltage sensor 12 detects a voltage value B. Further, a temperature sensor 13 for detecting the temperature T of the electrolytic solution 4 is provided at an arbitrary position in the container 8. Information on the current value A, voltage value B, and temperature T detected by these sensors 11 to 13 is transmitted to the control device 9.

  The control device 9 (estimating means, position changing means) is configured, for example, as an LSI device or an embedded electronic device in which a microprocessor, ROM, RAM, etc. are integrated. A current sensor 11, a voltage sensor 12, and a temperature sensor 13 are connected to the signal input side of the control device 9. On the other hand, a motor 7a is connected to the signal output side, and the rotational speed of the negative electrode 2 is controlled. As shown in FIG. 1A, a speed calculation unit 9a, a correction coefficient calculation unit 9b, and a control unit 9c are provided inside the control device 9. The speed calculation unit 9a functions as an estimation unit that estimates the generation of dendrites due to reduction of metal ions, and the control unit 9c functions as a position change unit that changes the positions of the opposing surfaces of the positive electrode 1 and the negative electrode 2.

  The speed calculation unit 9a calculates the rotation speed V of the negative electrode 2 based on the current value A and the voltage value B. Here, for example, the charge capacity C of the negative electrode 2 estimated from the current value A and the voltage value B is calculated. Alternatively, the maximum charging capacity determined from the size, composition, material, and the like of the negative electrode 2 is stored in advance, and the capacity decrease corresponding to the usage time and usage history of the secondary battery 10 is subtracted from the maximum charging capacity to charge the battery. The capacity C may be obtained.

  The speed calculator 9a sets the rotation speed V to be larger as the current value A is larger or the charging capacity C is smaller. As shown in FIG. 3A, the rotational speed V may be calculated based on a preset map of current value A, charging capacity C and rotational speed V, a mathematical formula, or the like. The value of the rotational speed V calculated here is transmitted to the controller 9c.

  In addition, as the current value A during charging increases, the reactivity (transfer rate) of lithium ions on the surface of the negative electrode active material layer 2b increases, and the likelihood of dendrite generation (possibility of dendrite generation) accordingly. Will increase. On the other hand, since the amount of current (unit density) per unit surface area of the negative electrode active material layer 2b is reduced by setting the rotational speed V to be large, the probability of dendrite generation is reduced.

  Further, the smaller the charge capacity C, the maximum value of lithium ions that can be inserted into the negative electrode 2 per unit time (that is, the maximum number of lithium ions that can be taken into the negative electrode active material layer 2b by the intercalation reaction). ) Decreases and the charging speed decreases. On the other hand, since the total area of the 2nd opposing surface 2c which opposes the 1st opposing surface 1c of the positive electrode 1 increases during unit time by setting the rotational speed V large, it is negative electrode per unit time. 2 increases the maximum value of lithium ions that can be inserted, and the charging speed increases.

  The correction coefficient calculator 9b calculates a correction coefficient K for the rotational speed V of the negative electrode 2 based on the temperature T. Here, the correction coefficient K is set smaller as the temperature T is higher, and the correction coefficient K is set larger as the temperature T is lower. The value of the correction coefficient K may be obtained on the basis of a correspondence map or a mathematical formula between the preset temperature T and the correction coefficient K as shown in FIG. 3B, for example. Note that the vertical axis of FIG. 3B is a logarithmic scale, and exponentially as the temperature T decreases from the normal temperature (based on the value of the correction coefficient K at the normal temperature (for example, 25 [° C.]) ( A characteristic that the correction coefficient K increases abruptly and the correction coefficient K decreases logarithmically (gently) as the temperature T rises above normal temperature is given. The value of the correction coefficient K calculated here is transmitted to the control unit 9c.

  The lower the temperature T, the lower the reactivity in the vicinity of the surface of the negative electrode active material layer 2b and the lower the charging rate. On the other hand, by setting the rotation speed V large, the total area of the second facing surface 2c that faces the first facing surface 1c of the positive electrode 1 increases during a unit time, so that lithium ions are not charged during charging. The probability of being taken into the negative electrode active material layer 2b increases, and the charging speed increases.

  The control unit 9c controls the rotation speed VM of the motor 7a during charging of the secondary battery 10 based on the rotation speed V calculated by the speed calculation unit 9a and the correction coefficient K calculated by the correction coefficient calculation unit 9b. Is. The motor rotation speed VM is given by, for example, the product of the rotation speed V and the correction coefficient K. Note that the motor rotation speed VM may be calculated based on a correspondence map or a mathematical expression between the rotation speed V and the correction coefficient K set in advance and the motor rotation speed VM. The control unit 9c transmits a control signal corresponding to the motor rotation speed VM to the motor 7a, and performs control such that the actual rotation speed of the motor 7a matches the motor rotation speed VM.

[1-2. flowchart]
Inside the control device 9, the flowchart shown in FIG. 4 is repeatedly executed at a predetermined cycle.
In step A10, based on the current value A detected by the current sensor 11, it is determined whether or not the secondary battery 10 is charged or discharged. For example, when the current value A is 0, it is determined that neither charging nor discharging is performed, and this flow is finished as it is. On the other hand, when the current value A is not 0, the process proceeds to step A20.

  In step A20, it is determined whether charging or discharging is being performed. The charge / discharge state can be determined based on the sign of the current value A (current direction), the sign of the voltage value B detected by the voltage sensor 12, and the like. If it is determined that the battery is being charged, the process proceeds to Step A30 to drive the negative electrode 2 to rotate. On the other hand, when it is determined that discharging is in progress, the process proceeds to step A60.

  In step A30, the charge capacity C of the negative electrode 2 is calculated in the speed calculation unit 9a, and the rotation speed V is calculated based on the current value A and the charge capacity C. In subsequent Step A40, the correction coefficient K is calculated based on the temperature T of the electrolytic solution 4 in the correction coefficient calculation unit 9b. Thereafter, in step A50, the product of the rotational speed V and the correction coefficient K is calculated as the motor rotational speed VM, and the motor 7a is controlled based on this. The motor 7a is rotationally driven until the charging of the secondary battery 10 is completed, for example.

  On the other hand, when the process proceeds from step A20 to step A60, the negative electrode 2 is formed in accordance with the discharge rate and amount of power so that the portion of the surface of the negative electrode active material layer 2b where the lithium ions are inserted faces the positive electrode 1. Driven. When the discharge speed is constant, the negative electrode 2 can be driven to rotate at a constant speed. Moreover, if the rotation speed of the negative electrode 2 is high, even if the discharge speed is not constant, it is possible to supply power without delay. On the other hand, when the rotation speed of the negative electrode 2 is low, the rotation speed may be set according to the discharge speed.

[1-3. Action, effect]
(1) In the secondary battery 10 described above, the entire negative electrode 2 in which the surface area of the negative electrode active material layer 2b is set larger than the surface area of the first facing surface 1c is rotationally driven. At this time, the position of the 2nd opposing surface 2c on the negative electrode active material layer 2b moves, and the site | part on the negative electrode 2 facing the 1st opposing surface 1c is changed. Thereby, the current density about the surface of the negative electrode 2 can be reduced, and the active material utilization rate per unit surface area of the negative electrode active material layer 2b can be reduced.

  Therefore, lithium ions ionized in the electrolytic solution 4 can be made difficult to deposit on the surface of the negative electrode 2, and the generation of dendrites can be suppressed. Even if a dendrite seed crystal is generated on the surface of the negative electrode 2, the seed crystal can be moved to the outside of the second facing surface 2c, and dendrite growth can be suppressed. In addition, if the size of the seed crystal is very small, it is possible to ionize the entire amount in the electrolytic solution 4 without leaving an insulating portion during discharge.

  Furthermore, since it becomes difficult to produce dendrite in the negative electrode 2, the range of selection of an electrode material and an active material can be expanded, and the performance of a secondary battery can be improved. For example, if metallic lithium is used for the negative electrode current collector 2a and the negative electrode active material layer 2b, the capacity density of the negative electrode 2 can be increased.

(2) Further, since the negative electrode 2 of the secondary battery 10 is formed in an endless annular shape, the second opposing surface 2c is set with the center of the ring as the rotation axis without changing the position or moving direction of the negative electrode 2. Can be moved continuously.
Thereby, precipitation of a lithium crystal can be suppressed over a long time. Furthermore, by continuously rotating and driving the negative electrode 2 during charging without stopping, the active material utilization rate for the entire surface of the negative electrode active material layer 2b can be reduced, and the effect of suppressing the precipitation of lithium crystals is enhanced. be able to.

(3) In addition, the negative electrode 2 continuously moves while the secondary battery 10 is being charged. Thereby, the variation in current density due to electrode design and manufacturing accuracy can be leveled, and local concentration of dendrites can be prevented. That is, the size of the generated dendrite can be reduced, the minute dendrite can be dispersed over a wide range, and the growth in the height direction can be suppressed.
As described above, since the minute dendrite is ionized in the electrolytic solution 4 at the time of discharge, the dendrite generated widely and shallowly can be treated as not practically present.

  (4) In particular, in the secondary battery 10 described above, since the rotation speed V is set larger as the current value A during charging is larger, the amount of current (current density) per unit surface area of the negative electrode active material layer 2b is reduced. And the occurrence probability of dendrites can be reduced. The current density on the surface of the negative electrode active material layer 2b depends on the total area and the current value A of the second facing surface 2c that is in a state of facing the first facing surface 1c during the unit time. Therefore, it is possible to carry out control to keep the current density constant by adjusting the rotation speed V when the current value A fluctuates.

  (5) Generally, the higher the temperature T of the electrolytic solution 4 is, the more lithium ion intercalation reaction is promoted during charging, and the lower the temperature T is, the lower the reactivity is. In consideration of such temperature characteristics, in the secondary battery 10 described above, the lower the temperature T, the larger the rotation speed V is set. Therefore, the probability that lithium ions are taken into the negative electrode active material layer 2b, and the negative electrode active material The probability that the lithium in the layer 2b is ionized can be increased, and the charge rate and the discharge performance can be increased.

(6) Further, in the secondary battery 10 described above, the rotation speed V is set larger as the charge capacity C is smaller. Thereby, the maximum amount of lithium ions that can be inserted into the negative electrode 2 per unit time can be increased, and the charging rate can be increased. For example, even if the charge capacity C of the negative electrode 2 decreases due to secular change, the larger the amount of decrease, the shorter the time required for full charge and the charge efficiency can be maintained.
In addition, the charge capacity C per unit surface area of the negative electrode 2 can be freely set regardless of the electrochemical characteristics of the positive electrode 1 and the type of active material, and the degree of freedom in designing the secondary battery 10 is increased. be able to.

  (7) In the secondary battery 10, since the scraper 5 is provided on the outer periphery of the negative electrode 2, even if dendrite is deposited on the surface of the negative electrode active material layer 2 b, the dendrite is scraped with the rotation of the negative electrode 2. And the deposition height can be kept below a predetermined distance. Therefore, a short circuit between the positive electrode 1 and the negative electrode 2 due to dendrite can be reliably prevented.

[1-4. Negative electrode shape modification 1]
FIG. 5 shows a secondary battery 20 as a modified example in which the shape of the negative electrode 2 of the above-described embodiment is changed. Here, elements similar to those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted. Whereas the negative electrode 2 described above is rigid enough to maintain the ring shape, the negative electrode 21 of this modification is formed in a deformable film shape, and the peripheral surface of the drive gear 7b and the periphery of the tensioner 7c. Wound around the surface. Further, on the path through which the negative electrode 21 is conveyed, a removal tank 22 for removing dendrites generated on the surface of the negative electrode 21, a cleaning tank 23 for regenerating the negative electrode active material layer 2b, a regeneration tank 24, and drying A unit 25 is interposed.

  Inside the removal tank 22, a scraper 5, a gap control device 26, and a stacking tray 27 are provided. The scraper 5 is supported by the case of the removal tank 22 via the gap control device 26 so that the distance between the tip of the scraper 5 and the negative electrode active material layer 2b is a predetermined distance. The predetermined distance can be arbitrarily adjusted by the gap control device 26. The stacking tray 27 is a dendrite tray that has been scraped off by the scraper 5. The greater the amount of dendrite accumulated on the accumulation tray 27, the lower the concentration of lithium ions in the electrolytic solution 4. Therefore, it is possible to determine the replacement and replenishment timing of the electrolytic solution 4 based on the amount of dendrite deposited on the accumulation tray 27.

  The cleaning tank 23 (decomposing means) is for chemically decomposing and removing lithium, lithium compounds, carbon compounds, fluorine compounds, etc. adhering to the surface of the negative electrode active material layer 2b, or removing the negative electrode active material layer 2b itself. It is chemically decomposed and removed. A cleaning liquid 23a is stored inside the cleaning tank 23, and the negative electrode 21 is immersed in the cleaning liquid 23a. At least substances unnecessary for the charge / discharge reaction are decomposed and removed from the surface of the negative electrode active material layer 2 b that has passed through the inside of the cleaning tank 23.

  The regeneration tank 24 (regeneration means) is a tank for performing a chemical treatment for stacking a new negative electrode active material on the surface of the negative electrode active material layer 2b and adjusting the surface condition. A regeneration solution 24a is stored inside the regeneration tank 24, and the negative electrode 21 is immersed in the regeneration solution 24a. When the negative electrode active material layer 2 b itself is removed in the cleaning tank 23, the negative electrode active material layer 2 b is regenerated in the regeneration tank 24. The drying unit 25 is a device for drying and fixing and fixing the negative electrode active material layer 2b on the surface of the negative electrode current collector 2a. Inside the drying unit 25, a drying device 25a for drying the negative electrode 21 is provided. When the negative electrode 21 passes through the vicinity of the drying device 25a, moisture is removed, and the negative electrode active material layer 2b is dried and fixed and fixed to the surface of the negative electrode current collector 2a.

  Thus, by providing the device for regenerating the negative electrode active material layer 2b on the transport path of the negative electrode 21, the function of the negative electrode 21 can be restored after removing the dendrite, and the useful life of the negative electrode 21 is extended. be able to. Therefore, the performance of the secondary battery 20 can be improved and the battery can be used for a long time. Further, if the negative electrode active material layer 2b, which is the surface layer of the negative electrode 21, is decomposed and regenerated, the performance of the negative electrode 21 can always be maintained as a new product, and a reduction in the charge capacity C can be prevented.

  In the secondary battery 20 as this modification, the scraper 5 is supported by the case of the removal tank 22 via the gap control device 26, and the distance between the tip of the scraper 5 and the negative electrode active material layer 2b can be adjusted. It is. For example, even when the distance between the tip of the scraper 5 and the negative electrode active material layer 2b is expanded due to aging of the surface of the negative electrode active material layer 2b (or wear of the scraper 5), the distance can be reduced. . Therefore, the control accuracy of the dendrite precipitation height can be improved.

  Moreover, by providing the scraper 5 inside the removal tank 22, scattering of the metal lithium crystal scraped off from the surface of the negative electrode active material layer 2b can be prevented, and the cleanliness of the electrolytic solution 4 can be maintained. . Furthermore, the characteristics of the electrolyte solution 4 can be quantitatively grasped from the amount of dendrite accumulated in the accumulation tray 27, and the maintainability of the secondary battery 10 can be improved.

[1-5. Negative electrode shape modification 2]
FIG. 6A shows a secondary battery 20 as a second modified example in which the shape of the negative electrode 21 of the modified example is changed. Here, the same elements as those in the first embodiment and the modification described above are denoted by the same reference numerals, and the description thereof is omitted. The negative electrode 21 is formed in a belt shape instead of an annular shape, and both ends of the negative electrode 21 are wound around a reel. One end of the negative electrode 21 is connected to the first reel 28, and the other end of the negative electrode 21 is connected to the second reel 29. Both of these reels 28 and 29 are provided so as to be rotatable in the forward and reverse directions by drive gears 7b and 7f.

  The length of the negative electrode 21 is sufficiently longer than the moving speed of the negative electrode 2. For example, the negative electrode 2 of the negative electrode 21 is wound so that the time required for the negative electrode 2 wound only on the first reel 28 side to be wound only on the second reel 29 side is several tens to several thousand hours. A standard moving speed and the length of the negative electrode 2 are set. Further, when all the negative electrodes 2 are wound around either the first reel 28 or the second reel 29 during the driving of the negative electrode 2, the rotation direction of the drive gears 7b and 7f is controlled to be reversed. The negative electrode 2 continues to be driven in the opposite direction.

  By such control, even when the negative electrode 21 having a non-annular shape is used, the secondary battery 20 having the same functions and effects as the first embodiment can be obtained. In addition, if the removal tank 22, the cleaning tank 23, the regeneration tank 24, and the drying unit 25 are provided on the transport path of the negative electrode 2, the secondary battery 20 having the same operations and effects as the above-described modified example is obtained. be able to.

[1-6. Other variations]
In the above-described embodiment, the secondary battery 10 including the scraper 5 that scrapes off the dendrite deposited on the surface of the negative electrode active material layer 2b is exemplified. The processing device 15 (shown by a broken line in FIG. 1) may be used.

  For example, even if the surface treatment device 15 for repairing the SEI film (Solid Electrolyte Interface; a protective film generated at the interface between the negative electrode 2 and the electrolytic solution 4) is supplied by supplying a small amount of lithium to the surface layer of the negative electrode active material layer 2b. Good. By providing such a surface treatment device 15, it is possible to improve the filling property of lithium ions related to charging and discharging into the negative electrode 2, and the performance of the secondary battery 10 can be improved.

  In the above-described embodiment, the controller 9 drives the motor 7a. However, the means for driving the negative electrode 2 is not limited to this. For example, in the case of the secondary battery 10 mounted on a vehicle, the negative electrode 2 may be driven using the driving force of the vehicle, or the drive gear 7b is rotated by spring power or human power. It is good also as a structure. When spring power is used, a spring or the like may be provided in place of the motor 7a. When human power is used, a lever handle or the like interlocked with the drive gear 7b may be provided instead of the motor 7a.

  In the above-described embodiment, the positive electrode 1 is disposed outside the negative electrode 2 and the motor 7a, the drive gear 7b, the tensioner 7c, and the like are disposed inside the negative electrode 2, but the positive electrode 1, the negative electrode 2, The specific arrangement position of the drive device 7 is not limited to this. For example, as illustrated in FIG. 6B, the driving device 7 may be disposed outside the negative electrode 2, or the positive electrode 1 may be disposed inside the negative electrode 2.

  In the above-described embodiment, the negative electrode 2 is rotationally driven during charging. However, the negative electrode 2 can be rotationally driven during discharging. In this case, as the rotation speed V of the negative electrode 2 increases, the amount of lithium ionized from the negative electrode active material layer 2b becomes more uniform in the circumferential direction, and the discharge reaction can be stabilized. Even during charging, as the rotational speed V of the negative electrode 2 is increased, the concentration distribution of lithium inserted into the negative electrode active material layer 2b becomes uniform in the circumferential direction, and the charging reaction can be stabilized. Therefore, it is conceivable that the rotation speed V is set to a sufficiently high speed so that the lithium ion intercalation reaction is leveled even in the maximum current state.

  Moreover, although the above-mentioned embodiment demonstrated the case where the secondary battery 10 was a lithium ion secondary battery, the kind of battery is not limited to this. For example, the same structure and configuration as in the above-described embodiment can be applied to a lithium metal secondary battery using metallic lithium for the negative electrode 2, a zinc-based secondary battery, or the like. If at least a battery in which dendrite is likely to be deposited on the electrode is applied, the same operation and effect as in the above embodiment can be obtained by applying the same structure and configuration as in the above embodiment.

  Further, in the above-described embodiment, the whole of the negative electrode 2 is illustrated as being rotationally driven. However, it is sufficient that at least the negative electrode active material layer 2b of the negative electrode 2 moves. For example, when the negative electrode active material layer 2b is slidably provided with respect to the negative electrode current collector 2a, only the negative electrode active material layer 2b may be moved.

  In the above-described embodiment, the negative electrode active material layer 2b of the negative electrode 2 is formed so that the surface area of the negative electrode active material layer 2b is larger than the area of the first counter surface 1c, and the second counter surface 2c of the negative electrode 2 is moved. Instead of this, the first facing surface 1c of the positive electrode 1 may be moved. For example, it can be considered that the positive electrode 1 moves around the outer periphery of the negative electrode 2 so that the distance between the positive electrode 1 and the negative electrode 2 is constant. As long as at least the relative position between the first facing surface 1c and the second facing surface 2c is changed, the same operations and effects as those of the above-described embodiment are achieved.

  In addition, it is preferable that a large area is formed at the pole on the side where dendrites are generated. For example, in the case of a secondary battery in which dendrite is likely to be generated in the positive electrode 1, the surface area of the positive electrode active material layer 1b of the positive electrode 1 is preferably formed larger than the area of the second facing surface 2c.

[2. Second embodiment]
[2-1. Device configuration]
The secondary battery 30 of 2nd embodiment is shown to Fig.7 (a), (b), and FIG. The same elements as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted. The negative electrode 31 of the secondary battery 30 is formed in a deformable film shape (strip shape) similarly to the negative electrode 21 according to the above-described modification. Both ends of the negative electrode 31 are wound around a reel, one end of the negative electrode 31 is connected to the first reel 32, and the other end of the negative electrode 31 is connected to the second reel 33. The first reel 32 is engaged with the drive gear 7 b and the second reel 33 is engaged with the shaft 7 d fixed to the container 8.

  If each of the first reel 32 and the second reel 33 is detachable from the drive gear 7b and the shaft 7d, the negative electrode 31 can be replaced. In this case, as shown by a broken line in FIG. 7B, by incorporating the negative electrode 31, the first reel 32, and the second reel 33 in the single cartridge 35, the incorporation into the secondary battery 30 is facilitated. The negative electrode 31 can be easily replaced.

  The secondary battery 10 of the first embodiment moves the negative electrode 2 continuously, whereas the secondary battery 30 of the second embodiment has the negative electrode 31 when it is determined that the performance of the negative electrode 31 has deteriorated. The part which functions as an electrode is changed. The direction in which the negative electrode 31 is moved is the extending direction of the strip-shaped negative electrode 31. That is, the negative electrode 31 may be moved in both the forward direction in which the negative electrode 31 is wound on the first reel 32 side and the reverse direction in which the negative electrode 31 is wound on the second reel 33 side, or may be moved in only one direction. Good.

  The negative electrode 31 includes a negative electrode current collector 31a and a negative electrode active material layer 31b formed on the surface thereof. The negative electrode current collector 31a is a part connected to the conductive wire via the negative electrode current collector 2d, and is formed of, for example, a strip-shaped metal foil whose back surface is reinforced with synthetic fiber or resin. The negative electrode active material layer 31b is formed on the side (surface) facing the positive electrode 1 of the negative electrode current collector 31a.

  Hereinafter, as in the first embodiment, a positive-side facing surface that faces the negative electrode 31 is referred to as a first facing surface 1c, and a negative-side facing surface that faces the positive electrode 1 is referred to as a second facing surface 31c. Call. The surface area of the negative electrode active material layer 31b is formed larger than the surface area of the first facing surface 1c. The region on the negative electrode active material layer 31b is divided into the same size as the first facing surface 1c, and each region is called a sector (segmented region).

  It is assumed that each sector is arranged without a gap from a sector adjacent in the extending direction of the negative electrode 31. In FIG. 8, the boundary lines of the sectors are indicated by broken lines. The sector corresponds to a region where lithium ions can be exchanged with the positive electrode 1 in a state where the position of the negative electrode 31 is fixed.

  The negative electrode 31 of the present embodiment is driven so that the portion facing the first facing surface 1c is switched for each sector. As shown in FIGS. 7A and 7B, the drive device 7 for the negative electrode 31 is provided with a motor 7a, a drive gear 7b, a shaft 7d, and a pair of pulleys 7e. The operation of the motor 7a is controlled by a control device 34. Be controlled. The pulley 7e is a fixed pulley that is rotatably supported with respect to the container 8 of the secondary battery 30, and the negative electrode 31 is wound around the outer periphery thereof. The pair of pulleys 7e function so as to keep the distance between the positive electrode 1 and the negative electrode 31 substantially constant.

  Further, a scraper 5 (removing means) is provided in the vicinity of the outer periphery of the negative electrode 31 for scraping off dendrite that may be deposited on the surface of the negative electrode active material layer 2b. FIG. 7B shows a scraper 5 that removes dendrite from the surface of the negative electrode 31 that moves in the forward direction, and a scraper 5 that removes dendrite from the surface of the negative electrode 31 that moves in the reverse direction.

  The control device 34 (estimating means, position changing means) is configured as an LSI device or an embedded electronic device similar to the control device 9 of the first embodiment, for example. A current sensor 11, a voltage sensor 12, and a temperature sensor 13 are connected to the signal input side of the control device 34. On the other hand, a motor 7a is connected to the signal output side, and the rotational speed of the negative electrode 31 is controlled. As shown in FIG. 7A, a switching condition determination unit 34 a and a switching control unit 34 b are provided inside the control device 34. The switching condition determination unit 34a functions as an estimation unit that estimates the generation of dendrites due to reduction of metal ions, and the switching control unit 34b functions as a position changing unit that changes the positions of the opposing surfaces of the positive electrode 1 and the negative electrode 31.

  The switching condition determination unit 34a determines the timing for moving the negative electrode 31 based on the current value A, voltage value B, temperature T, and the like detected by the sensors 11-13. Here, for example, it is determined whether or not the following conditions are satisfied. When any one of the conditions is satisfied, it is determined that the dendrite may have been deposited (or the dendrite generation amount and the deposition amount may have exceeded a specified amount). The determination result in the switching condition determination unit 34a is transmitted to the switching control unit 34b.

A. A predetermined time has elapsed since the last time the negative electrode 31 was moved. The charge capacity C has fallen below the specified capacity. The internal resistance value R has exceeded the specified value. A charging current greater than the specified current is input. F. Charging started at a temperature below the specified temperature. An abnormality was found in the charge / discharge curve

  Condition A is based on the sector usage period. The “predetermined time” of the condition A may be a relatively long time such as several months or years. Alternatively, based on the current value A, voltage value B, temperature T, etc., the length of the predetermined time may be set from a preset control map or arithmetic expression. For example, the higher the current value A and the voltage value B, the easier the dendrite precipitates, and the predetermined time may be shortened. Similarly, the predetermined time may be shortened on the assumption that the lower the temperature T, the easier the dendrite precipitates.

  The condition B is based on the maximum value of lithium ions that can be inserted into the negative electrode 31 per unit time, and the condition C is based on the internal resistance value R of the secondary battery 30. The charge capacity C is estimated from, for example, the current value A detected by the current sensor 11 and the voltage value B detected by the voltage sensor 12 during charging. Similarly, the internal resistance value R is estimated from the current value A and voltage value B during charging / discharging. Condition D is satisfied when the current value A during charging is equal to or greater than a predetermined current, and Condition E is satisfied when the temperature T detected by the temperature sensor 13 is equal to or lower than the predetermined temperature. .

  Condition F is based on the charge / discharge characteristics of the secondary battery 30. For example, as shown by a solid line in FIG. 9A, a voltage fluctuation curve during charging of the secondary battery 30 under a constant current condition [curve showing the relationship between the voltage value B and time (or charge capacity C)] Is stored in advance, and it is determined that an abnormality has occurred when the actual voltage value B converted to a value under a constant current condition shows a behavior greatly deviating from the voltage fluctuation curve. Since the charge capacity C decreases as the amount of dendrite deposited increases, the charging time is extended as shown by the broken line in FIG. Therefore, it can be determined that an abnormality has occurred when the delay in the rise of the voltage fluctuation curve becomes large.

  Alternatively, as shown by a solid line in FIG. 9B, a voltage fluctuation curve at the time of discharging the secondary battery 30 under a constant current condition is stored in advance, and an actual voltage value B is obtained under a constant current condition. It may be determined that an abnormality has occurred when the value converted into a value shows a behavior that deviates significantly from the voltage fluctuation curve. In this case, a hatched area centered on the solid voltage fluctuation curve in FIG. 9B is set, and it is determined that the voltage fluctuation curve during discharge fluctuates within the hatched area, and the curve is normal. It can be considered that an abnormality has occurred when the shape of the line exceeds the shaded area. Alternatively, as indicated by the alternate long and short dash line in FIG. 9B, it may be determined that an abnormality has occurred when the voltage fluctuation curve is accompanied by a rapid voltage drop.

  The switching control unit 34b switches the sector to be used by driving the motor 7a when at least one of the above conditions A to F is satisfied by the switching condition determining unit 34a. However, when lithium remains in the negative electrode active material layer 31b of the sector used when the condition is satisfied, the sector is switched after waiting for the lithium to be almost completely desorbed and ionized. Shall. That is, the timing at which the sector is actually switched is after the sector in use is almost completely discharged.

  From this, the secondary battery 30 cannot be used continuously when lithium is not inserted in the negative electrode active material layer 31b of the sector to be used next. Therefore, it is preferable to determine whether or not to perform sector switching at the start of charging of the secondary battery 30 and to start charging after the determination is made.

  For example, the start of charging is determined based on the current value A detected by the current sensor 11, and when it is determined that charging has started, the mode shifts to a diagnostic mode in which sector switching is determined. In the diagnostic mode, it is judged whether there is a possibility that dendrite has occurred in the sector in use (or the deposition amount may have exceeded the specified amount), and if there is a possibility, the sector is switched. Charging starts after the control is performed. If there is no possibility that dendrite has occurred, charging is started without switching sectors.

  On the other hand, when lithium is inserted into the negative electrode active material layer 31b of the sector to be used next, even when the secondary battery 30 is in normal use (during discharge), there is a slight amount related to sector switching. Except for the time lag, the secondary battery 30 can be continuously used (discharged). For example, when the above-described cardridge negative electrode 31 is used, lithium may be inserted into the negative electrode active material layer 31b in advance.

[2-2. flowchart]
FIG. 10 is a flowchart illustrating a control procedure performed inside the control device 34, and is performed in a diagnosis mode when charging of the secondary battery 30 is started.
In Step B10, it is determined whether or not the condition A is satisfied by the switching condition determination unit 34a. If the predetermined time has elapsed since the last time the negative electrode 31 was moved, it is determined that dendrite may have precipitated, and the process proceeds to step B70. If this condition is not satisfied, the process proceeds to step B20. move on.

In Step B20, it is determined whether or not the condition B is satisfied. If the charge capacity C of the negative electrode 31 is below the predetermined capacity, it is determined that dendrite may have been deposited, and the process proceeds to step B70. If this condition is not satisfied, the process proceeds to step B30.
Similarly, in Steps B30, B40, B50, and B60, it is determined whether Condition C, Condition D, Condition E, and Condition F are satisfied. When each condition is satisfied, the process proceeds to Step B70. On the other hand, when none of the conditions A to F is satisfied, it is determined that there is no possibility that the dendrite has precipitated, and the diagnosis mode is terminated. In this case, charging is started without switching sectors.

On the other hand, in step B70, the switching control unit 34b performs control to completely discharge the sector used at that time. The remaining power in the sector is estimated from the current value A detected by the current sensor 11 and the voltage value B detected by the voltage sensor 12. If the remaining power becomes equal to or lower than the predetermined power, the control proceeds to step B80.
In step B80, a control signal for driving the motor 7a is output from the switching control unit 34b, and the sector to be used is switched. Thereby, since the unused sector functions as an electrode on the negative electrode 31 side, the secondary battery 30 exhibits the same performance as a new battery.

[2-3. Action, effect]
(1) In the secondary battery 30, the region on the negative electrode active material layer 31b is divided into sectors having the same size as the first facing surface 1c, and the portion facing the first facing surface 1c is switched for each sector. It is done. Thus, by moving the second opposing surface 31c of the negative electrode 31 for each sector, the active material utilization rate per unit surface area of the negative electrode active material layer 31b can be reduced, and the generation of dendrite can be suppressed. it can. Further, it is possible to continue using unused sectors where no dendrite is generated, and the performance of the secondary battery 30 can be improved.

  (2) The sector switching is performed when it is determined that there is a possibility that dendrite has occurred in the sector in use. Already used sectors will not be used afterwards. Therefore, even if dendrite is generated on the sector before movement, further dendrite growth can be prevented. Further, when there is no possibility of the occurrence of dendrite, the control for moving the sector is not performed, so that it is possible to save energy for driving the motor 7a.

  (3) Further, the negative electrode 31 of the secondary battery 30 is formed in a strip shape in which both end portions are wound around the first reel 32 and the second reel 33. Thereby, parts other than the site | part which opposes the 1st opposing surface 1c can be put together compactly in the state wound up by the 1st reel 32 and the 2nd reel 33. FIG. That is, the surface area of the negative electrode active material layer 31b of the negative electrode 31 can be remarkably increased as compared with the volume occupied by the first reel 32 and the second reel 33, and the negative electrode 31 and the secondary battery 30 can be easily downsized. It becomes. Further, if the negative electrode 31, the first reel 32, and the second reel 33 are built in a single cartridge 35, a new negative electrode 31 can be used simply by replacing the cartridge 35. Maintainability can be improved.

  (4) Further, in the secondary battery 30 described above, when at least one of the conditions A to F is satisfied, the control for moving the sector is performed, so that dendrite growth can be reliably prevented. it can. In addition, by verifying the possibility of dendrite generation from various viewpoints such as the charging capacity C, the internal resistance value R, the current value A, the temperature T, and the voltage value B variation curve as well as the usage time of the negative electrode 31, The determination accuracy can be improved.

  (5) Furthermore, in the secondary battery 30 described above, when lithium remains in the negative electrode active material layer 31b of the sector used when any of the conditions A to F is satisfied, The sector is switched after waiting for the lithium to be almost completely ionized. By interposing such a delay process, the lithium ion concentration in the electrolytic solution 4 can be maintained, and the performance of the secondary battery 30 can be ensured.

[2-4. Modified example]
In the second embodiment described above, the belt-shaped negative electrode 31 having both ends wound around the reels 32 and 33 is exemplified, but the shape of the negative electrode 31 is not limited to this. For example, as in the first embodiment, an endless ring can be used. In this case, as shown in FIG. 5, by providing a removal tank 22, a cleaning tank 23, a regeneration tank 24, a drying unit 25, etc. on the electrode transport path, it is possible to regenerate used sectors. Switching can be repeated permanently. Further, the replacement of the negative electrode 31 is not necessary, and the running cost of the secondary battery 30 can be reduced.

  In the second embodiment described above, the controller 34 controls the operation of the motor 7a to move the position of the second facing surface 31c on the negative electrode active material layer 31b. Similarly to the modification of the embodiment, the driving force, spring power, and human power of the vehicle may be used as means for driving the negative electrode 31.

[3. Third embodiment]
[3-1. Device configuration]
In the first embodiment, the case where the negative electrode 2 is rotationally driven at the time of charging is described, and in the second embodiment, the case where the second facing surface 31c moves when there is a possibility that dendrite has occurred has been described. On the other hand, the secondary battery 40 of the third embodiment incorporates both of these elements. A secondary battery 40 of the third embodiment is shown in FIG. Elements similar to those in the first embodiment and the second embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

  The negative electrode 41 of the secondary battery 40 is an endless annular electrode in which a negative electrode active material layer 41b is formed on the surface of a negative electrode current collector 41a. Similarly to the negative electrode 2 of the first embodiment, the negative electrode 41 is formed in a ring shape that is circular in a side view, and is provided so as to be rotatable with respect to the container 8 with the center of the ring as a rotation axis. On the other hand, the negative electrode 41 is formed wider than the negative electrode 2 of the first embodiment, and is wider than the width of the positive electrode 1 facing the negative electrode 41.

  In addition, a plurality of tracks are divided into strips on the surface of the negative electrode active material layer 41b. These tracks are arranged along the extending direction of the negative electrode 41. In FIG. 12, the boundary line of the track is indicated by a broken line. The track corresponds to a region where lithium ions can be exchanged with the positive electrode 1 when the negative electrode 41 is rotationally driven with the position of the positive electrode 1 fixed. While the sector of the second embodiment is adjacent to the extending direction of the negative electrode 31, the track of the third embodiment is arranged to be adjacent to the direction perpendicular to the extending direction of the negative electrode 41.

  In addition, the secondary battery 40 is provided with a driving device 7 for rotationally driving the negative electrode 41 and a second driving device 42 for moving the positive electrode 1. Hereinafter, as in the first embodiment, a positive-side facing surface that faces the negative electrode 41 is referred to as a first facing surface 1c, and a negative-side facing surface that faces the positive electrode 1 is referred to as a second facing surface 41c. Call.

  The driving device 7 drives the negative electrode 41 so that the position of the second facing surface 41 c on the negative electrode active material layer 41 b moves along the extending direction of the negative electrode 41. That is, the direction in which the driving device 7 moves the negative electrode 41 is the X direction in FIG. On the other hand, the second drive device 42 drives the positive electrode 1 so that the position of the first facing surface 1c on the positive electrode active material layer 1b moves in the adjacent direction of the track. That is, the direction in which the second drive device 42 moves the positive electrode 1 is the Y direction in FIG. The operations of the driving device 7 and the second driving device 42 are controlled by the control device 43.

  For example, the control device 43 is configured as an LSI device or an embedded electronic device similar to the control device 9 of the first embodiment. A current sensor 11, a voltage sensor 12, and a temperature sensor 13 are connected to the signal input side of the control device 43. On the other hand, the motor 7a and the second drive device 42 are connected to the signal output side, and the rotational speed V of the negative electrode 41 and the timing of movement of the positive electrode 1 are controlled. As shown in FIG. 11, a speed calculation unit 43a, a correction coefficient calculation unit 43b, a control unit 43c, a switching condition determination unit 43d, and a switching control unit 43e are provided inside the control device 43.

  The speed calculation unit 43a and the correction coefficient calculation unit 43b correspond to the speed calculation unit 9a and the correction coefficient calculation unit 9b of the first embodiment, respectively, and calculate the rotation speed V and the correction coefficient K of the negative electrode 41. The control unit 43c corresponds to the control unit 9c of the first embodiment, and the rotation speed VM of the motor 7a when charging the secondary battery 40 is based on the calculated rotation speed V and the correction coefficient K. To control.

  The switching condition determination unit 43d corresponds to the switching condition determination unit 34a of the second embodiment, and has a timing for moving the positive electrode 1 based on the current value A, voltage value B, temperature T, and the like detected by the sensors 11-13. Judgment. Here, for example, it is determined whether or not the above conditions A to F are satisfied. In the second embodiment, it is determined whether or not there is a possibility that the dendrite is deposited in the sector in use, whereas in the third embodiment, the possibility that the dendrite is deposited on the track in use. It is determined whether or not there is.

  The switching control unit 43e corresponds to the switching control unit 34b of the second embodiment, and drives the second driving device 42 when at least one of the above conditions A to F is satisfied by the switching condition determination unit 43d. , To change the track to be used. The track switching timing is set after the lithium remaining in the negative electrode active material layer 41b of the used track is almost completely ionized.

[3-2. Action, effect]
In the above secondary battery 40, the entire negative electrode 41 is rotationally driven during charging, and the position of the second facing surface 41c continuously moves in the X direction in any track. Thereby, like the secondary battery 10 of 1st embodiment, the current density about the surface of the negative electrode 41 can be reduced, and the active material utilization rate per unit surface area of the negative electrode active material layer 41b can be reduced. it can. As described above, the secondary battery 40 of the third embodiment has the same effect as the secondary battery 10 of the first embodiment.

  On the other hand, when it is determined that there is a possibility that dendrite has occurred in the track in use, the positive electrode 1 slides in the Y direction and faces the first opposing surface 1c (that is, the second track). The track on which the opposing surface 41c exists is switched. Thereby, the active material utilization rate per unit surface area of the negative electrode active material layer 41b can be reduced, generation of dendrites can be suppressed, and unused tracks can be used continuously. Thus, the secondary battery 40 of the third embodiment also has the same effect as the secondary battery 30 of the second embodiment.

1 Positive electrode (first electrode)
2, 21, 31, 41 Negative electrode (second electrode)
5 Scraper (removal means)
7 Drive unit (position changing means)
9, 34, 43 Control device (estimating means, position changing means)
10, 20, 30, 40 Secondary battery 22 Removal tank (removal means)
23 Cleaning tank (removal means)
24 Regeneration tank (regeneration means)

Claims (9)

A first electrode;
A second electrode disposed opposite the first electrode and having a larger surface area than the facing surface of the first electrode;
An electrolyte solution disposed between the first electrode and the second electrode and including at least a metal ion;
A secondary battery, comprising: a position changing unit that changes a position of an opposing surface of the second electrode with respect to the first electrode. Comprising estimation means for estimating the generation of dendrites due to reduction of the metal ions,
The secondary battery according to claim 1, wherein the position changing unit changes the position of the facing surface of the second electrode based on the estimation result of the estimating unit. The secondary battery according to claim 2, wherein the estimation unit estimates generation of the dendrite based on a charge / discharge state. The second electrode has a plurality of segmented regions on its surface;
A portion of each of the segment regions is disposed to face the first electrode;
The said position change means selects the segment area | region which opposes said 1st electrode for every said segment area | region based on the generation state of the said dendrite obtained by the said estimation means, The Claim 2 or 3 characterized by the above-mentioned. Secondary battery. The position changing means changes the position of the facing surface of the second electrode after moving the metal ion or the reduced product of the metal ion containing the dendrite in the electrolyte or to the first electrode. The secondary battery according to claim 4, wherein the secondary battery is characterized. The secondary battery according to claim 1, further comprising a removing unit that scrapes off dendrite generated on the second electrode. Decomposition means for chemically decomposing the surface layer of the second electrode;
The secondary battery according to claim 1, further comprising a reproducing unit that regenerates the surface layer after the decomposition of the surface layer by the decomposition unit. The secondary battery according to claim 1, wherein the second electrode is formed in an endless annular shape. The secondary battery according to any one of claims 1 to 7, wherein the second electrode is formed in a band shape having an end wound on a reel.

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