JP2012028024A - Capacity recovery method for lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacity recovery method for a lithium ion secondary battery that efficiently recovers battery capacity (discharge capacity) having decreased owing to insertion of Li to a non-opposite part of a negative electrode active material layer.SOLUTION: The capacity recovery method for the lithium ion secondary battery having the negative electrode active material layer comprising an opposite part opposed to a positive electrode active material layer with a separator interposed therebetween and the non-opposite part in which the positive electrode active material layer opposed with the separator interposed is not present includes a leaving process (step S4) of leaving the lithium ion secondary battery as it is in a temperature environment of 45-65°C.

Description

  The present invention relates to a capacity recovery method for a lithium ion secondary battery.

In recent years, lithium ion secondary batteries have been used as driving power sources for portable electronic devices such as hybrid vehicles, notebook computers, and video camcorders.
Patent Document 1 discloses a wound-type electrode in which the width of the active material coating portion (negative electrode active material layer) of the negative electrode plate is set larger than the width of the active material coating portion (positive electrode active material layer) of the positive electrode plate. A lithium ion secondary battery including a plate group (electrode body) is disclosed.

JP 2005-190913 A

That is, in the lithium ion secondary battery of Patent Document 1, the negative electrode active material layer is located on the opposite side of the negative electrode active material layer across the width direction of the negative electrode active material layer with the separator interposed therebetween. And a non-facing portion where there is no positive electrode active material layer facing each other.
In this lithium ion secondary battery, when charged, Li (lithium ions) released from the positive electrode active material layer (positive electrode active material) is inserted into the opposite portion of the negative electrode active material layer (negative electrode active material of the opposite portion). Is done. On the other hand, when discharge is performed, Li released from the facing portion of the negative electrode active material layer (negative electrode active material of the facing portion) is inserted into the positive electrode active material layer (positive electrode active material).

  By the way, in the lithium ion secondary battery having a non-opposing portion of the negative electrode active material layer like the lithium ion secondary battery of Patent Document 1, it was released from the positive electrode active material layer during charging (particularly during high rate charging). A part of Li (lithium ion) may be inserted into the non-opposing part. In addition, a part of Li (lithium) inserted into the facing portion of the negative electrode active material layer (negative electrode active material of the facing portion) may move (diffuse) to the non-facing portion (negative electrode active material of the non-facing portion). there were.

  However, since the non-opposing portion of the negative electrode active material layer does not have an opposing positive electrode active material layer, it is difficult to release Li in the non-opposing portion during discharge. That is, this non-opposing portion is a negative electrode active material layer, but hardly participates in discharge. For this reason, the amount of Li that can be released from the negative electrode active material layer during discharge is reduced by the amount of Li inserted into the non-opposing portion, that is, the battery capacity may be reduced.

  The present invention has been made in view of such problems, and can efficiently recover the battery capacity (discharge capacity) that has been reduced by inserting Li into the non-opposing portion of the negative electrode active material layer. It is an object of the present invention to provide a capacity recovery method for a lithium ion secondary battery.

  One embodiment of the present invention is a positive electrode plate including a positive electrode current collector plate, and a positive electrode active material layer including a positive electrode active material and disposed on the positive electrode current collector plate, a negative electrode current collector plate, and a negative electrode active material A negative electrode plate having a negative electrode active material layer disposed on the negative electrode current collector plate, and a separator interposed between the positive electrode plate and the negative electrode plate, and the positive electrode via the separator A lithium ion secondary battery in which an active material layer and the negative electrode active material layer face each other, wherein the negative electrode active material layer includes a facing portion facing the positive electrode active material layer via the separator, and the separator. A lithium ion secondary battery capacity recovery method comprising: a non-facing portion in which the positive electrode active material layer opposed to the non-facing portion is present, wherein the lithium ion secondary battery is placed in a temperature environment of 45 ° C. to 65 ° C. LITIU that is left unattended It is the capacity recovery method of ion secondary battery.

  In the above-described capacity recovery method for a lithium ion secondary battery, a lithium ion secondary battery having a non-opposing portion (a portion where a positive electrode active material layer facing through a separator does not exist) in the negative electrode active material layer is 45 ° C. or higher and 65 ° C. Leave in a temperature environment of ℃ or less (keep standing in a state where no charge / discharge is performed). In other words, a standing treatment for leaving the lithium ion secondary battery is performed while maintaining the temperature of the lithium ion secondary battery within a range of 45 ° C to 65 ° C.

  By performing such a leaving treatment, Li inserted into the non-opposing portion of the negative electrode active material layer with use can be efficiently moved to the opposing portion of the negative electrode active material layer. Li that has moved to the facing portion of the negative electrode active material layer can contribute to the charge / discharge reaction again. Therefore, according to the capacity recovery method of the lithium ion secondary battery described above, it is possible to efficiently recover the battery capacity (discharge capacity) that has decreased due to the insertion of Li in the non-opposing portion of the negative electrode active material layer. .

  Furthermore, the capacity recovery method of the lithium ion secondary battery described above, wherein the leaving treatment is a capacity recovery method of a lithium ion secondary battery in which the lithium ion secondary battery is left in a state where the SOC is 30% or less. good.

  In the above-described capacity recovery method of the lithium ion secondary battery, the lithium ion secondary battery is maintained in a temperature environment of 45 ° C. or more and 65 ° C. or less in a state where the SOC (State Of Charge) of the lithium ion secondary battery is 30% or less. The neglected process is performed under the neglect. In other words, in a state where the battery voltage of the lithium ion secondary battery is set to a value equal to or lower than the battery voltage value at which the lithium ion secondary battery becomes SOC 30%, the temperature of the lithium ion secondary battery is 45 ° C. or higher and 65 ° C. or lower. Perform neglecting treatment to leave in the environment.

By setting the lithium ion secondary battery to a state where the SOC is 30% or less, Li inserted into the non-opposing portion of the negative electrode active material layer with use can easily move to the opposing portion of the negative electrode active material layer. Therefore, by performing the above-described leaving treatment, Li inserted into the non-opposing portion of the negative electrode active material layer with use can be effectively moved to the opposing portion of the negative electrode active material layer. For this reason, the battery capacity (discharge capacity) reduced by inserting Li into the non-opposing portion of the negative electrode active material layer can be effectively recovered.
Note that the lithium ion secondary battery has a property that the battery voltage value decreases as the SOC value decreases.

  Furthermore, in the method for recovering the capacity of the lithium ion secondary battery described above, an SOC adjustment process for adjusting the SOC value of the lithium ion secondary battery to an SOC specified value of 30% or less and the SOC adjustment process were performed. It is preferable to use a capacity recovery method for a lithium ion secondary battery in which a capacity recovery process including the above-described storage process for leaving the lithium ion secondary battery is repeated a plurality of times.

  Li was inserted into the non-facing portion of the negative electrode active material layer by repeatedly performing a capacity recovery process including a SOC adjustment process and a neglect process (a capacity recovery process combining the SOC adjustment process and the neglect process) multiple times. Thus, the battery capacity (discharge capacity) reduced by the above can be recovered more effectively.

  Furthermore, in any one of the above-described methods for recovering the capacity of a lithium ion secondary battery, the leaving treatment is performed by discharging the battery voltage of the lithium ion secondary battery so that the lithium ion secondary battery becomes SOC 0%. The lithium ion secondary battery capacity may be recovered by leaving the lithium ion secondary battery in a state where the voltage value is lower than the voltage value.

  In the above-described capacity recovery method of the lithium ion secondary battery, the lithium ion secondary battery is discharged, and the battery voltage is determined from the battery voltage value (terminal voltage value) at which the SOC of the lithium ion secondary battery becomes 0%. In this state, the lithium ion secondary battery is left to stand.

  By setting the battery voltage of the lithium ion secondary battery to such a low voltage value as described above, Li inserted into the non-opposing part of the negative electrode active material layer with use is further increased by the opposing part of the negative electrode active material layer. It becomes easy to move to. Therefore, by performing the above-described leaving treatment, Li inserted into the non-opposing portion of the negative electrode active material layer with use can be more effectively moved to the opposing portion of the negative electrode active material layer. For this reason, the battery capacity (discharge capacity) reduced by inserting Li into the non-opposing part of the negative electrode active material layer can be recovered more effectively.

  Further, in the capacity recovery method of the lithium ion secondary battery, the battery voltage value of the lithium ion secondary battery is set to a voltage regulation value lower than a battery voltage value at which the lithium ion secondary battery has SOC 0%. A capacity recovery method including a capacity recovery process including a discharge process for discharging until reaching the capacity and a process for leaving the lithium ion secondary battery that has been subjected to the discharge process repeated a plurality of times. Is preferred.

  Reduced by inserting Li into the non-opposing portion of the negative electrode active material layer by repeatedly performing capacity recovery processing (capacity recovery processing combining discharge processing and storage processing) including discharge processing and storage processing multiple times. The obtained battery capacity (discharge capacity) can be recovered more effectively.

  Further, in any one of the above-described capacity recovery methods of the lithium ion secondary battery, the leaving treatment includes a capacity recovery method of the lithium ion secondary battery in which the leaving time of the lithium ion secondary battery is 4 hours or more. Good.

  In the above-described capacity recovery method of the lithium ion secondary battery, the leaving time of the lithium ion secondary battery is set to 4 hours or longer in the leaving treatment (one leaving treatment). Thereby, the battery capacity (discharge capacity) reduced by inserting Li into the non-opposing portion of the negative electrode active material layer can be recovered more effectively.

1 is a perspective view of a lithium ion secondary battery according to an embodiment. It is a perspective view of the positive electrode plate of the lithium ion secondary battery. It is a perspective view of the negative electrode plate of the lithium ion secondary battery. It is an expanded sectional view of the same negative electrode plate, and corresponds to the AA sectional view of FIG. It is a graph showing the relationship between a leaving temperature and a capacity | capacitance recovery rate. It is a graph showing the relationship between SOC (battery voltage) and a capacity | capacitance recovery rate. It is a graph showing the relationship between leaving time and a capacity | capacitance recovery rate. It is a graph showing the relationship between the number of times of capacity recovery processing and the capacity recovery rate. 2 is a flowchart showing a flow of a capacity recovery method for a lithium ion secondary battery according to Example 1; 6 is a flowchart showing a flow of a capacity recovery method for a lithium ion secondary battery according to Example 2;

Next, a capacity recovery method for a lithium ion secondary battery according to an embodiment of the present invention will be described with reference to the drawings.
First, the lithium ion secondary battery 100 used in this embodiment will be described.

  As illustrated in FIG. 1, the lithium ion secondary battery 100 includes an electrode body 110 and a battery case 180 that accommodates the electrode body 110. The electrode body 110 includes a positive electrode plate 130, a negative electrode plate 120, and a separator 150. The separator 150 is made of polyethylene, and is interposed between the positive electrode plate 130 and the negative electrode plate 120 to separate them. The separator 150 is impregnated with an electrolytic solution 160 having lithium ions.

  The battery case 180 is made of aluminum and has a battery case main body 181 and a sealing lid 182. Among these, the battery case main body 181 has a bottomed rectangular box shape. Note that an insulating film (not shown) made of a resin and bent in a box shape is interposed between the battery case main body 181 and the electrode body 110.

  The sealing lid 182 has a rectangular plate shape, closes the opening of the battery case body 181, and is welded to the battery case body 181. A rectangular plate-shaped safety valve 197 is sealed on the sealing lid 182.

  Further, a plate-like positive electrode current collecting member 191 bent in a crank shape is welded to the positive electrode plate 130 of the electrode body 110 (see FIG. 1). Further, a plate-like negative electrode current collecting member 192 bent in a crank shape is welded to the negative electrode plate 120. Of the positive electrode current collecting member 191 and the negative electrode current collecting member 192, the positive electrode terminal portion 191A and the negative electrode terminal portion 192A located at the respective tips penetrate the sealing lid 182 and protrude from the lid surface 182A. Insulating members 195 made of electrically insulating resin are interposed between the positive electrode terminal portion 191A and the sealing lid 182 and between the negative electrode terminal portion 192A and the sealing lid 182, respectively.

  Moreover, the electrolyte solution 160 adds lithium hexafluorophosphate as a solute to the mixed organic solvent which adjusted ethylene carbonate (EC) and diethyl carbonate (DEC) to EC: EMC = 3: 7 by volume ratio. A non-aqueous electrolyte with a lithium ion concentration of 1 mol / l.

  The electrode body 110 is a wound type in which a belt-like positive electrode plate 130 and a negative electrode plate 120 are wound into a flat shape via a belt-like separator 150 (see FIG. 1). Specifically, the strip-shaped positive electrode plate 130, the negative electrode plate 120, and the separator 150 extending in the longitudinal direction DA are wound in the longitudinal direction DA to form a wound electrode body 110 (FIGS. 1 to 4). reference). In the electrode body 110, the positive electrode active material layer 131 of the positive electrode plate 130 and the negative electrode active material layer 121 of the negative electrode plate 120 face each other with the separator 150 interposed therebetween (see FIG. 4).

  As shown in FIG. 2, the positive electrode plate 130 has a belt-like shape extending in the longitudinal direction DA. The positive electrode current collector plate 138 made of aluminum foil and both main surfaces of the positive electrode current collector plate 138 extend in the longitudinal direction DA. It has two positive electrode active material layers 131 and 131 arranged in a strip shape. The positive electrode active material layer 131 includes a positive electrode active material 137 made of lithium nickelate, a conductive material (not shown) made of acetylene black, and a binder (not shown) made of polyvinylidene fluoride (PVDF). .

  Further, as shown in FIG. 3, the negative electrode plate 120 is formed on a negative electrode current collector plate 128 made of a copper foil in a strip shape extending in the longitudinal direction DA, and on both main surfaces 128 F and 128 F of the negative electrode current collector plate 128. It has two negative electrode active material layers 121 and 121 arranged in a strip shape extending in the direction DA. The negative electrode active material layer 121 includes a negative electrode active material 127 made of graphite (graphite) and a binder (not shown) made of PVDF.

  As shown in FIGS. 3 and 4 (AA sectional view of FIG. 3), the negative electrode active material layer 121 includes a facing portion 122 that faces the positive electrode active material layer 131 with the separator 150 interposed therebetween, and a separator 150. And the non-opposing portion 123 (the first non-opposing portion 124 and the second non-opposing portion 125 described below) in which the positive electrode active material layer 131 facing each other does not exist. Specifically, the negative electrode active material layer 121 has a larger area than the positive electrode active material layer 131, and the non-opposing portion 123 is positioned around the opposing portion 122.

  The non-opposing portions 123 are two second non-opposing portions 125 and 125 located on both ends of the negative electrode active material layer 121 in the longitudinal direction DA, and 2 located on both ends of the negative electrode active material layer 121 in the width direction DB, respectively. It consists of two first non-opposing parts 124, 124. Note that the position of the boundary between the non-facing portion 123 (the first non-facing portion 124 and the second non-facing portion 125) and the facing portion 122 in the negative electrode active material layer 121 is located between the negative electrode plate 120, the separator 150, and the positive electrode plate 130. It is determined when the electrode body 110 is formed by turning. In FIG. 4, for reference, the positions of the positive electrode plate 130 and the separator 150 when the electrode body 110 is formed are indicated by a two-dot chain line.

  By the way, conventionally, in a lithium ion secondary battery having a non-opposing portion of the negative electrode active material layer, a part of Li (lithium ions) released from the positive electrode active material layer during charging (particularly during high rate charging) is non- It was sometimes inserted in the opposite part. In addition, a part of Li (lithium ion) inserted in the facing portion of the negative electrode active material layer (negative electrode active material of the facing portion) moves (diffuses) to the non-facing portion (negative electrode active material of the non-facing portion). There was a thing. However, since the opposing positive electrode active material layer does not exist in the non-opposing portion, it is difficult to release Li in the non-opposing portion during discharge. That is, the non-opposing portion is hardly involved in the discharge while being the negative electrode active material layer. For this reason, the amount of Li that can be released from the negative electrode active material layer during discharge is reduced by the amount of Li inserted in the non-opposing portion, and the battery capacity may be reduced.

  In contrast, in the present embodiment, the capacity of the lithium ion secondary battery is reduced as a result of the following capacity recovery process, which is caused by the insertion of Li into the non-opposing portion of the negative electrode active material layer (discharge). Capacity). The capacity recovery method (capacity recovery process) of the lithium ion secondary battery according to the present embodiment will be described below.

  First, SOC adjustment processing is performed on the lithium ion secondary battery 100 (SOC is adjusted). Specifically, for example, using a known charging / discharging device, the lithium ion secondary battery 100 is discharged (or charged), and the SOC of the lithium ion secondary battery 100 is a specified value of 30% or less (for example, , SOC 0%). In other words, the lithium ion secondary battery 100 is discharged (or charged), and the battery voltage value of the lithium ion secondary battery 100 is set to a battery voltage value (between terminals) at which the lithium ion secondary battery 100 becomes SOC 30%. Voltage value) or less (in this embodiment, 3.54 V or less).

  Here, instead of the SOC adjustment process, the lithium ion secondary battery 100 may be discharged. Specifically, the lithium ion secondary battery 100 is discharged, and the battery voltage (inter-terminal voltage) of the lithium ion secondary battery 100 is set to a battery voltage value at which the lithium ion secondary battery 100 has SOC 0% (this embodiment). Then, the voltage is lowered to a specified value (for example, 1.5 V) lower than 3.0 V).

The SOC of the lithium ion secondary battery 100 can be grasped from the battery voltage value of the lithium ion secondary battery 100. Specifically, in the lithium ion secondary battery 100, for example, when the battery voltage value is 4.1V, SOC is 100%, when the battery voltage value is 3.54V, SOC is 30%, and the battery voltage value is 3.0V. SOC is 0%.
Moreover, in a well-known charging / discharging apparatus, the battery voltage value (The voltage value between terminals of 191 A of positive electrode terminal parts and 192 A of negative electrode terminals) of the lithium ion secondary battery 100 is detectable. Therefore, the battery voltage value of the lithium ion secondary battery 100 can be grasped by a known charging / discharging device.

Next, the lithium ion secondary battery 100 that has been subjected to the SOC adjustment process (or the discharge process) is left to stand. Specifically, the lithium ion secondary battery 100 subjected to the SOC adjustment process (or discharge process) is left in a temperature environment of 45 ° C. or more and 65 ° C. or less for a predetermined time. For example, the temperature of the lithium ion secondary battery 100 is set to 45 ° C. to 65 ° C. for a predetermined time by heating the lithium ion secondary battery 100 having an SOC of 30% or less by SOC adjustment processing with a heater (not shown). Within the range (for example 45 ° C.). Alternatively, the lithium ion secondary battery 100 whose SOC is reduced to 30% or less by the SOC adjustment process is placed in a known constant temperature bath (not shown), and the temperature of the lithium ion secondary battery 100 is set to 45 ° C. to a predetermined time. The temperature is maintained within a range of 65 ° C. (for example, 45 ° C.).
The standing time is preferably 4 hours or longer.

  By performing such capacity recovery processing (processing including SOC adjustment processing (or discharge processing) and neglecting processing, in other words, processing combining SOC adjustment processing (or discharging processing) and neglecting processing), lithium is obtained. As the ion secondary battery 100 is used, Li inserted into the non-facing portion 123 (the first non-facing portion 124 and the second non-facing portion 125) of the negative electrode active material layer 121 is efficiently converted into the negative electrode active material layer. 121 can be moved to the facing portion 122. Li moved to the facing portion 122 of the negative electrode active material layer 121 can contribute to the charge / discharge reaction again. Therefore, according to the capacity recovery method of the lithium ion secondary battery of the present embodiment, the battery capacity (discharge capacity) decreased by inserting Li into the non-facing portion 123 of the negative electrode active material layer 121 is efficiently recovered. Can be made.

(Capacity recovery test)
Next, preferable conditions for recovering the battery capacity of the lithium ion secondary battery 100 were investigated.
First, the preferable leaving temperature range was investigated. Specifically, first, when Li is inserted into the non-facing portion 123 of the negative electrode active material layer 121, the battery capacity (discharge capacity) compared to the lithium ion secondary battery 100 in the initial state (new state). A lithium ion secondary battery 100 (hereinafter also referred to as a sample battery) is prepared. Such a sample battery can be manufactured as follows, for example.

  First, a plurality of lithium ion secondary batteries 100 in an initial state (for example, a battery capacity of 5.0 Ah) are prepared. Then, these batteries are subjected to CCCV (Constant Current / Constant Voltage) charging at a constant current of 1 C and an upper limit battery voltage value of 4.1 V under a temperature environment of 25 ° C. to obtain SOC 100%. In the present embodiment, when the battery voltage value of the lithium ion secondary battery 100 is 4.1 V, the SOC is 100%. Thereafter, these batteries are left for one week. As a result, when Li is inserted into the non-opposing portion 123 of the negative electrode active material layer 121, the battery capacity (discharge capacity) is reduced by 5% compared to the lithium ion secondary battery 100 in the initial state (new state). The obtained lithium ion secondary battery 100 (sample battery) can be obtained.

  In addition, the battery capacity (discharge capacity) of each battery is measured as follows. First, for each battery, the upper limit battery voltage value is set to 4.1 V with a constant current of 1 C, and CCCV charging is performed to obtain SOC 100%. Thereafter, for each battery, the lower limit battery voltage value is set to 3.0 V at a constant current of 1 C, and CCCV discharge is performed to obtain SOC 0%. The amount of electricity discharged at this time is measured as the battery capacity (discharge capacity). In the present embodiment, when the battery voltage value of the lithium ion secondary battery 100 is 3.0 V, the SOC is 0%.

Further, 1C is a current value at which the discharge having a rated capacity value (nominal capacity value) is constant-current discharged and discharge is completed in one hour. When the rated capacity (nominal capacity) of the lithium ion secondary battery 100 is 5.0 Ah, 1C = 5.0 A.
Also, SOC is an abbreviation for State Of Charge.

  Further, in the present embodiment, in the sample battery manufactured as described above, the factor that the battery capacity (discharge capacity) is reduced by 5% from the initial state (initial capacity) is caused by the non-facing portion 123 of the negative electrode active material layer 121. It was confirmed that Li was inserted. Specifically, the sample battery produced as described above was disassembled, and the amount of Li in the non-facing portion was measured by a known analysis method. And the amount of Li of the non-facing part in a sample battery was compared with the amount of Li of the non-facing part in the lithium ion secondary battery 100 of an initial state (measured beforehand by a well-known analysis method). As a result, in the sample battery, Li corresponding to 5% of the initial capacity (battery capacity of the lithium ion secondary battery 100 in the initial state) increases in the non-facing portion as compared with the lithium ion secondary battery 100 in the initial state. It was.

  Next, six sample batteries (sample batteries 1 to 6) with SOC 0% (battery voltage value 3.0 V) were prepared, and these sample batteries were left untreated. Specifically, these sample batteries were allowed to stand in a thermostat (not shown) for 4 hours with different temperatures (temperature in a thermostat not shown) when left.

  Specifically, the sample battery 1 was left in the thermostatic bath for 4 hours with the temperature in the thermostatic bath set at −15 ° C. (left in a temperature environment of −15 ° C. for 4 hours). The sample battery 2 was left in the thermostatic bath for 4 hours with the temperature in the thermostatic bath set to 0 ° C. (left in a temperature environment of 0 ° C. for 4 hours). The sample battery 3 was allowed to stand in the thermostatic bath for 4 hours with the temperature in the thermostatic bath set to 25 ° C. (left in a temperature environment of 25 ° C. for 4 hours).

  The sample battery 4 was left in the thermostatic bath for 4 hours with the temperature in the thermostatic bath set at 45 ° C. (left in a temperature environment of 45 ° C. for 4 hours). The sample battery 5 was left in the constant temperature bath for 4 hours at a temperature in the constant temperature bath of 60 ° C. (left in a temperature environment of 60 ° C. for 4 hours). The sample battery 6 was left in the constant temperature bath for 4 hours at a temperature in the constant temperature bath of 70 ° C. (left in a 70 ° C. temperature environment for 4 hours).

  Then, about the sample batteries 1-6, the battery capacity (battery capacity after leaving) was measured and the capacity recovery rate (%) was calculated. The capacity recovery rate is calculated based on the battery capacity of the sample battery before the neglected treatment as a reference, and when the battery capacity of the lithium ion secondary battery 100 in the initial state is recovered as a recovery rate of 100%. . That is, the capacity recovery rate is determined by leaving the battery capacity difference between the sample battery and the initial battery in which the battery capacity is reduced by 5% with respect to the lithium ion secondary battery 100 (also referred to as the initial battery) in the initial state. This is the ratio (%) of the increased (recovered) “sample battery capacity increase (recovery amount)”. For example, when the battery capacity of the lithium ion secondary battery 100 in the initial state is 5.0 Ah and the battery capacity (4.75 Ah) of the sample battery is recovered to 4.85 Ah by the above-described leaving treatment, the capacity recovery rate = ((4.85-4.75) / (5.0-4.75)) × 100 = 40%.

  In the sample battery 1 left in a temperature environment of −15 ° C., the capacity recovery rate was about 10%. In the sample battery 2 left in a temperature environment of 0 ° C., the capacity recovery rate was about 18%. In the sample battery 3 left in a temperature environment of 25 ° C., the capacity recovery rate was about 32%. In the sample battery 4 left in a temperature environment of 45 ° C., the capacity recovery rate was about 47%. In the sample battery 5 left in a temperature environment of 60 ° C., the capacity recovery rate was about 56%. In the sample battery 6 left in a temperature environment of 70 ° C., the capacity recovery rate was about 40%. Based on these results, a graph showing the relationship between the standing temperature and the capacity recovery rate was created. This graph is shown in FIG.

  From the graph of FIG. 5, it can be seen that the capacity recovery rate is increased by setting the leaving temperature (environment temperature at the time of leaving) within the range of 45 ° C. to 65 ° C. Therefore, by leaving the lithium ion secondary battery 100 in a temperature environment of 45 ° C. or higher and 65 ° C. or lower, the non-opposing portion 123 (the first non-facing portion 124 and the second non-facing portion 125 of the negative electrode active material layer 121). It can be said that the battery capacity (discharge capacity) reduced by the insertion of Li into the battery can be efficiently recovered. From this result, it can be said that the leaving temperature (environmental temperature during leaving) is preferably 45 ° C. or more and 65 ° C. or less.

  Next, the preferred SOC value (or battery voltage value) when left untreated was investigated. Specifically, seven sample batteries (batteries whose battery capacity is reduced by 5% from the initial capacity) are prepared (sample batteries 7 to 13), and these sample batteries are set to SOC (or battery voltage value). Differentiated, and left in a temperature environment of 25 ° C. for 4 hours.

  Specifically, the sample battery 7 was left for 4 hours in a temperature environment of 25 ° C. in a state where the SOC was 80% (battery voltage value was 3.9 V). The sample battery 8 was left in a temperature environment of 25 ° C. for 4 hours in a state where the SOC was 60% (battery voltage value was 3.73 V). The sample battery 9 was left for 4 hours in a temperature environment of 25 ° C. in a state where the SOC was 30% (battery voltage value was 3.54 V). The sample battery 10 was left in a temperature environment of 25 ° C. for 4 hours in a state where the SOC was 0% (battery voltage value was 3.0 V).

  The sample batteries 11 to 13 were discharged for 4 hours under a temperature environment of 25 ° C. in a state where the battery voltage value was set to a value lower than the battery voltage value (specifically, 3.0 V) at which SOC becomes 0%. I left it alone. Specifically, the sample battery 11 is discharged, and the battery voltage value is set to 2.79 V, which is lower than the battery voltage value (specifically, 3.0 V) at which SOC becomes 0%. Thereafter, the sample battery 11 was left in a temperature environment of 25 ° C. for 4 hours. Further, the sample battery 12 was discharged to have a battery voltage value of 2.37 V, and then the sample battery 12 was left in a temperature environment of 25 ° C. for 4 hours. Moreover, after discharging the sample battery 13 to make the battery voltage value 1.5V, the sample battery 13 was left in a temperature environment of 25 ° C. for 4 hours.

  Next, for sample batteries 7 to 13, the battery capacity (battery capacity after being left) was measured, and the capacity recovery rate (%) was calculated as described above. In the sample battery 7 in which the SOC is 80% (battery voltage value is 3.9 V), the capacity recovery rate is about 5%. In the sample battery 8 in which the SOC is 60% (battery voltage value is 3.73 V), the capacity recovery rate is about 10%. In the sample battery 9 in which the SOC is 30% (battery voltage value is 3.54 V), the capacity recovery rate is about 20%. In the sample battery 10 in which the SOC was 0% (battery voltage value was 3.0 V), the capacity recovery rate was about 32%.

  In the sample batteries 11 to 13 in which the battery voltage value is lower than the battery voltage value (specifically, 3.0 V) at which the SOC becomes 0%, a sample in which the SOC is 0% (battery voltage value is 3.0 V) The capacity recovery rate was higher than that of the battery 10. Specifically, in the sample battery 11 having a battery voltage value of 2.79 V, the capacity recovery rate was about 50%. In the sample battery 12 having a battery voltage value of 2.37 V, the capacity recovery rate was about 60%. In the sample battery 13 having a battery voltage value of 1.5 V, the capacity recovery rate was about 70%. Based on these results, a graph representing the relationship between SOC (or battery voltage value) and capacity recovery rate was created. This graph is shown in FIG.

  From the graph of FIG. 6, it can be seen that the capacity recovery rate is increased by leaving the lithium ion secondary battery in a state where the SOC is 30% or less (in other words, the battery voltage value is 3.54 V or less). In particular, the capacity recovery rate is greatly improved by leaving the lithium ion secondary battery in a state where the battery voltage value is lower than the battery voltage value (specifically, 3.0 V) at which SOC becomes 0%. I understand.

  Therefore, by leaving the lithium ion secondary battery 100 in a state where the SOC is 30% or less, the non-opposing portion 123 (the first non-facing portion 124 and the second non-facing portion 125) of the negative electrode active material layer 121 is Li. It can be said that the battery capacity (discharge capacity) reduced by insertion of can be efficiently recovered. In other words, in a state where the battery voltage of the lithium ion secondary battery 100 is set to a value equal to or lower than the battery voltage value (specifically, 3.54 V) at which the lithium ion secondary battery 100 has an SOC of 30%, By leaving the battery 100 unattended, the battery capacity (discharge capacity) decreased due to the insertion of Li into the non-opposing portion 123 (the first non-opposing portion 124 and the second non-opposing portion 125) of the negative electrode active material layer 121. It can be said that it can be recovered efficiently.

  In particular, by leaving the lithium ion secondary battery 100 in a state where the battery voltage value is lower than the battery voltage value (specifically, 3.0 V) at which SOC becomes 0%, It can be said that the battery capacity (discharge capacity) reduced by inserting Li into the facing portion 123 (the first non-facing portion 124 and the second non-facing portion 125) can be recovered more effectively. In the above test, the standing temperature is set to 25 ° C., but the same tendency is observed in relation to the SOC (battery voltage) and the capacity recovery rate at other standing temperatures (for example, temperatures of 45 ° C. or more and 65 ° C. or less). was gotten.

  Next, the relationship between the standing time and the capacity recovery rate was investigated. Specifically, six sample batteries (batteries whose battery capacity is reduced by 5% from the initial capacity) (sample batteries 14 to 19) are prepared, and the battery voltage value of these sample batteries is set to 1.5 V by discharging. After being lowered to a temperature of 25 ° C., it was left in a temperature environment of 25 ° C. with different standing times.

  Specifically, the sample battery 14 was left for 1 hour in a temperature environment of 25 ° C. The sample battery 15 was left for 2 hours in a temperature environment of 25 ° C. The sample battery 16 was left for 4 hours in a temperature environment of 25 ° C. The sample battery 17 was left for 8 hours in a temperature environment of 25 ° C. The sample battery 18 was left for 12 hours in a temperature environment of 25 ° C. The sample battery 19 was left for 16 hours in a temperature environment of 25 ° C.

  Thereafter, for the sample batteries 14 to 19, the battery capacity (battery capacity after being left) was measured, and the capacity recovery rate (%) was calculated as described above. In the sample battery 14 in which the standing time was 1 hour, the capacity recovery rate was about 32%. In the sample battery 15 in which the standing time was 2 hours, the capacity recovery rate was about 45%. In the sample battery 16 in which the standing time was 4 hours, the capacity recovery rate was about 62%. In the sample battery 17 in which the standing time was 8 hours, the capacity recovery rate was about 65%. In the sample battery 18 in which the standing time was 12 hours, the capacity recovery rate was about 66%. In the sample battery 19 in which the standing time was 16 hours, the capacity recovery rate was about 68%. Based on these results, a graph representing the relationship between the standing time and the capacity recovery rate was created. This graph is shown in FIG.

  From the graph of FIG. 7, it can be seen that the capacity recovery rate is increased by setting the standing time to 4 hours or longer. Accordingly, the battery capacity is reduced by inserting Li into the non-facing portion 123 (the first non-facing portion 124 and the second non-facing portion 125) of the negative electrode active material layer 121 by setting the standing time to 4 hours or longer. It can be said that (discharge capacity) can be effectively recovered. In the above test, the standing temperature is set to 25 ° C., but the same tendency is obtained in the relationship between the standing time and the capacity recovery rate at other standing temperatures (for example, temperatures of 45 ° C. or more and 65 ° C. or less). It was.

Next, the relationship between the number of capacity recovery processes and the capacity recovery rate was investigated. Here, the capacity recovery process refers to a process including the SOC adjustment process (or discharge process) and the leaving process described above, in other words, a process combining the SOC adjustment process (or discharge process) and the leaving process.
Specifically, five sample batteries (batteries whose battery capacity is reduced by 5% from the initial capacity) are prepared (sample batteries 20 to 24), and the capacity recovery process is repeated five times for these sample batteries. It was. Each time the capacity recovery process was completed, the battery capacity was measured for the sample batteries 20 to 24, and the capacity recovery rate (%) was calculated as described above.

In the sample batteries 20 to 24, the conditions of the SOC adjustment process (or discharge process) are different. Specifically, in the sample 20, the SOC adjustment process is performed prior to each leaving process, and the SOC of the battery is adjusted to 60%. In sample 21, the SOC adjustment process is performed prior to each leaving process, and the SOC of the battery is adjusted to 30%. In the sample 22, the SOC adjustment process is performed prior to each leaving process, and the SOC of the battery is adjusted to 0%. In sample 23, a discharge process is performed prior to each leaving process, and the battery voltage is reduced to 2.79V. In sample 24, a discharge process is performed prior to each leaving process, and the battery voltage is reduced to 1.5V.
In the sample batteries 20 to 24, the conditions for the neglecting process are the same. Specifically, the sample batteries 20 to 24 that have been subjected to the SOC adjustment process (or the discharge process) are left in a temperature environment of 25 ° C. for 4 hours.

Here, the result of each sample will be described in detail.
First, with respect to the sample 20, as a capacity recovery process, an SOC adjustment process for adjusting the SOC of the battery to 60% and a leaving process for 4 hours in a temperature environment of 25 ° C. were continuously performed. After completing the first capacity recovery process, the battery capacity of the sample battery 20 was measured, and the capacity recovery rate (%) was calculated as described above. Subsequently, the sample battery 20 was subjected to a second capacity recovery process, and then the battery capacity was measured to calculate the capacity recovery rate (%). In this manner, the sample 20 was subjected to the capacity recovery process five times, and the battery capacity was measured and the capacity recovery rate (%) was calculated every time the capacity recovery process (standby process) was completed. The result is indicated by * in FIG.

  As indicated by * in FIG. 8, in the sample 20 that is left to be adjusted after adjusting the SOC of the battery to 60%, the capacity recovery rate increases as the number of capacity recovery processes increases, and the capacity recovery process is repeated 3 By performing the process once, the capacity recovery rate could be about 30%. However, after the fourth time, the capacity recovery rate did not change even when the capacity recovery process was performed (that is, the battery capacity did not recover any more).

  Sample 21 was continuously subjected to an SOC adjustment process for adjusting the SOC of the battery to 30% and a leaving process for 4 hours in a temperature environment at 25 ° C. as a capacity recovery process. After completing the first capacity recovery process, the battery capacity of the sample battery 21 was measured, and the capacity recovery rate (%) was calculated as described above. Subsequently, a second capacity recovery process was performed on the sample battery 21, and then the battery capacity was measured to calculate the capacity recovery rate (%). In this way, the capacity recovery process was performed five times for the sample 21, and the battery capacity was measured and the capacity recovery rate (%) was calculated every time the capacity recovery process (standby process) was completed. The result is indicated by a cross in FIG.

  In the sample 21 where the battery SOC is adjusted to 30% and left as shown by x in FIG. 8, the capacity recovery rate increases as the number of capacity recovery processes is repeated, and the capacity recovery process is repeated 5 By performing the test once, the capacity recovery rate could be increased to about 80%.

  Sample 22 was continuously subjected to an SOC adjustment process for adjusting the SOC of the battery to 0% and a leaving process for 4 hours in a temperature environment of 25 ° C. as a capacity recovery process. After completing the first capacity recovery process, the battery capacity of the sample battery 22 was measured, and the capacity recovery rate (%) was calculated as described above. Subsequently, the sample battery 22 was subjected to a second capacity recovery process, and then the battery capacity was measured to calculate the capacity recovery rate (%). In this manner, the sample 22 was subjected to the capacity recovery process five times, and the battery capacity was measured and the capacity recovery rate (%) was calculated every time the capacity recovery process (standby process) was completed. The result is indicated by Δ in FIG.

  As indicated by a triangle in FIG. 8, in the sample 22 that is left to be adjusted after adjusting the SOC of the battery to 0%, the capacity recovery rate increases as the number of capacity recovery processes increases, and the capacity recovery process is repeated 4 The capacity recovery rate can be made 100% by performing the process once (that is, the battery capacity that is reduced by inserting Li into the non-opposing portion 123 of the negative electrode active material layer 121 can be recovered 100%. did it).

  For sample 23, as a single capacity recovery process, a discharge process for reducing the battery voltage to 2.79 V by discharge and a standing process for 4 hours in a temperature environment of 25 ° C. are performed continuously. It was. After completing the first capacity recovery process, the battery capacity of the sample battery 23 was measured, and the capacity recovery rate (%) was calculated as described above. Subsequently, the sample battery 23 was subjected to a second capacity recovery process, and then the battery capacity was measured to calculate the capacity recovery rate (%). In this way, the capacity recovery process was performed five times for the sample 23, and the battery capacity was measured and the capacity recovery rate (%) was calculated each time the capacity recovery process (standby process) was completed. The result is indicated by □ in FIG.

  As shown by the □ mark in FIG. 8, in the sample 22 which is left to stand by reducing the battery voltage to 2.79 V by discharging, the capacity recovery rate becomes about 50% by one capacity recovery process, and the second time ( By performing the capacity recovery process of the second time, the capacity recovery rate was able to be 100% (that is, the battery capacity decreased by inserting Li into the non-opposing portion 123 of the negative electrode active material layer 121, 100% recovery).

  For sample 24, as a capacity recovery process, a discharge process for reducing the battery voltage to 1.5 V by discharging and a leaving process for 4 hours in a temperature environment of 25 ° C. are continuously performed. It was. After completing the first capacity recovery process, the battery capacity of the sample battery 24 was measured, and the capacity recovery rate (%) was calculated as described above. Subsequently, the sample battery 24 was subjected to a second capacity recovery process, and then the battery capacity was measured to calculate the capacity recovery rate (%). In this manner, the sample 24 was subjected to the capacity recovery process five times, and the battery capacity was measured and the capacity recovery rate (%) was calculated each time the capacity recovery process (standby process) was completed. The results are indicated by ◇ in FIG.

  As shown by ◇ in FIG. 8, in the sample 23 which is left to stand by lowering the battery voltage to 1.5 V by discharging, the capacity recovery rate becomes about 70% by one capacity recovery process, and the second time ( By performing the capacity recovery process of the second time, the capacity recovery rate was able to be 100% (that is, the battery capacity decreased by inserting Li into the non-opposing portion 123 of the negative electrode active material layer 121, 100% recovery).

  From the above results, the capacity recovery process including the SOC adjustment process (or the discharge process) and the leaving process is repeatedly performed a plurality of times, so that Li is inserted into the non-facing portion 123 of the negative electrode active material layer 121. It can be said that the obtained battery capacity (discharge capacity) can be recovered more effectively.

  Here, the marks ◇ in FIG. 7 and FIG. 8 are compared. As can be seen from FIG. 7, the capacity recovery rate of the sample battery is 65% even if the sample battery is left to stand for 8 hours after being subjected to a discharge treatment for reducing the battery voltage to 1.5 V by discharging. Only rises to On the other hand, as can be seen from the symbol ◇ in FIG. 8, two discharge treatments are performed in which the battery voltage is reduced to 1.5 V by discharging prior to the leaving treatment of leaving the sample battery for 4 hours. If the storage is left for a total of 8 hours by the storage processing (capacity recovery processing is performed twice), the capacity recovery rate can be made 100%. Also from this, the capacity recovery process including the discharge process (or the SOC adjustment process) and the leaving process is repeated a plurality of times, and this is reduced by the insertion of Li into the non-facing portion 123 of the negative electrode active material layer 121. It can be said that the obtained battery capacity (discharge capacity) can be recovered more effectively.

Example 1
Next, an example of the capacity recovery method of the lithium ion secondary battery according to the present invention will be described with reference to FIG.
First, in step S1, it is determined whether or not a predetermined period has elapsed since the previous capacity recovery process. An example of the predetermined period is a period of 6 months. When the lithium ion secondary battery 100 is used as a power source for the vehicle, it is determined in step S1 whether or not the vehicle has traveled a predetermined travel distance after performing the previous capacity recovery process. You may do it. If the capacity recovery process has never been performed, it is determined in step S1 whether a predetermined period (for example, 6 months) has elapsed since the start of battery use.

If it is determined in step S1 that the predetermined period has not elapsed (No), the process ends (END) without proceeding to step S2.
On the other hand, if it is determined in step S1 that the predetermined period has elapsed (Yes), the process proceeds to step S2 and the battery capacity of the lithium ion secondary battery 100 is measured. Specifically, the battery capacity is measured as follows. First, with respect to the lithium ion secondary battery 100, the upper limit battery voltage value is set to 4.1 V at a constant current of 1 C, and CCCV charging is performed to obtain SOC 100%. Thereafter, the lower limit battery voltage value is set to 3.0 V at a constant current of 1 C, and CCCV discharge is performed to obtain SOC 0%. The amount of electricity discharged at this time is measured as the battery capacity (discharge capacity).

  Next, it progresses to step S3 and it is judged whether the capacity | capacitance reduction rate of the lithium ion secondary battery 100 is 5% or more. Here, the capacity reduction rate is the current time with respect to the battery capacity of the lithium ion secondary battery 100 (final battery capacity measured in step S5 to be described later) when the previous capacity recovery process (before the predetermined period) is completed. It is a ratio (%) indicating how much the battery capacity measured in step S2 is reduced. For example, when the battery capacity of the lithium ion secondary battery 100 when the previous capacity recovery process (before the predetermined period) is 5.0 Ah and the battery capacity measured in this step S2 is 4.75 Ah, Reduction rate = ((5.0−4.75) /5.0) × 100 = 5 (%). In step S3 of the first embodiment, the threshold value for the capacity reduction rate is set to 5%, but other values may be used.

If it is determined in step S3 that the capacity reduction rate is less than 5% (No), the process ends (END) without proceeding to step S4.
On the other hand, if it is determined in step S3 that the capacity reduction rate is 5% or more (Yes), the process proceeds to step S4 to perform the neglect process. Specifically, the lithium ion secondary battery 100 is left in an SOC 0% state, for example, in a temperature environment of 45 ° C. for 4 hours. At this time, the lithium ion secondary battery 100 is heated by, for example, a heater (not shown) and is maintained at 45 ° C.

  By the way, in Example 1, when the battery capacity of the lithium ion secondary battery 100 is measured in step S2, the SOC of the lithium ion secondary battery 100 is 0%. Therefore, in the first embodiment, the process of step S2 is also an SOC adjustment process for adjusting the SOC of the lithium ion secondary battery 100 to 0% (also serves as the SOC adjustment process). For this reason, in the present Example 1, it is not necessary to provide an SOC adjustment process separately after the battery capacity measurement process of step S2.

  Then, it progresses to step S5 and the battery capacity of the lithium ion secondary battery 100 is measured similarly to step S2. Subsequently, it progresses to step S6 and it is judged whether the battery capacity of the lithium ion secondary battery 100 has recovered | restored the predetermined ratio. Specifically, for example, it is determined whether or not the capacity recovery rate is 50% or more.

  Here, the capacity recovery rate is based on the battery capacity measured in step S2 (battery capacity before performing the neglecting process in step S4), and the lithium ion when the previous capacity recovery process (before the predetermined period) is finished. The time when the battery capacity of the secondary battery 100 is recovered is calculated as a capacity recovery rate of 100%. That is, the capacity recovery rate is a difference value between the battery capacity of the lithium ion secondary battery 100 when the previous capacity recovery process (before the predetermined period) is completed and the battery capacity measured in the current step S2 (for a predetermined period). This is the ratio (%) of the difference value (capacity recovery amount due to neglected processing) between the battery capacity measured in step S5 and the battery capacity measured in step S2 with respect to the amount of capacity decrease due to use.

Specifically, for example, the battery capacity of the lithium ion secondary battery 100 when the previous capacity recovery process (before the predetermined period) is completed is 5.0 Ah, and the battery capacity measured in the current step S2 is 4. When the battery capacity measured in step S5 is 4.85 Ah at 75 Ah, the capacity recovery rate = ((4.85−4.75) / (5.0−4.75)) × 100 = 40%.
Note that the threshold value of the capacity recovery rate is not limited to 50% and may be other values.

  If it is determined in step S6 that the battery capacity of the lithium ion secondary battery 100 has been recovered by a predetermined ratio (for example, the capacity recovery rate is 50% or more) (Yes), the process ends here (END). To do.

  On the other hand, if it is determined in step S6 that the battery capacity of the lithium ion secondary battery 100 has not recovered a predetermined rate (for example, the capacity recovery rate is less than 50%) (No), steps S4 to S6 are performed again. Perform the process. In this case, the capacity recovery process (process including the SOC adjustment process and the leaving process) is repeatedly performed a plurality of times. After that, if it is determined in step S6 that the battery capacity of the lithium ion secondary battery 100 has been recovered by a predetermined ratio (Yes), the process is ended (END).

  In Example 1, when the battery capacity of the lithium ion secondary battery 100 is measured in Step S5, the SOC of the lithium ion secondary battery 100 is 0%. Therefore, in the first embodiment, when performing the second neglecting process (the process of step S4), the process of step S5 performed before that adjusts the SOC of the lithium ion secondary battery 100 to 0%. It is also an SOC adjustment process (also serves as an SOC adjustment process). Accordingly, when it is determined in step S6 that the battery capacity of the lithium ion secondary battery 100 has not recovered by a predetermined ratio (No), the capacity recovery process (the SOC adjustment process (the processes of steps S2 and S5) and the neglected process ( The process including the process of step S4) is repeated a plurality of times (for example, twice).

(Example 2)
Next, another example of the capacity recovery method of the lithium ion secondary battery according to the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in that a discharge process is added before the neglecting process, and the others are the same. Therefore, here, the description will focus on the points different from the first embodiment, and the description of the same points will be omitted or simplified.

As shown in FIG. 10, first, similarly to steps S1 to S3 of the first embodiment, processes of steps T1 to T3 are performed. If it is determined in step T3 that the capacity reduction rate is less than 5% (No), the processing is ended (END) as in the first embodiment.
On the other hand, if it is determined in step T3 that the capacity reduction rate is 5% or more (Yes), the process proceeds to step T4, and a discharge process is performed. Specifically, the lithium ion secondary battery 100 is discharged, and the battery voltage (inter-terminal voltage) of the lithium ion secondary battery 100 is set to a battery voltage value at which the lithium ion secondary battery 100 has SOC 0% (this embodiment). Then, the voltage is lowered to a specified value (for example, 1.5 V) lower than 3.0 V).

Then, it progresses to step T5 and a neglect process is performed. Specifically, the lithium ion secondary battery 100 subjected to the above-described discharge treatment is left for 4 hours in a temperature environment of 45 ° C., for example.
Next, similarly to steps S5 and S6 of the first embodiment, the processes of steps T6 and T7 are performed. In step T7, for example, it is determined whether the capacity recovery rate has reached 50% or more. If it is determined in step T7 that the battery capacity of the lithium ion secondary battery 100 has not recovered by a predetermined ratio (No), the processes of steps T4 to T7 are performed again. In this case, the capacity recovery process (the process including the discharge process and the leaving process, the processes of steps T4 and T5) is repeated a plurality of times. If it is determined in step T7 that the battery capacity of the lithium ion secondary battery 100 has been recovered by a predetermined ratio (Yes), the process is ended (END).

  In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.

100 lithium ion secondary battery 120 negative electrode plate 121 negative electrode active material layer 122 facing portion 123 non-facing portion 127 negative electrode active material 128 negative electrode current collector plate 130 positive electrode plate 131 positive electrode active material layer 137 positive electrode active material layer 138 positive electrode current collector plate 150 separator

Claims (4)

A positive electrode plate having a positive electrode current collector plate, and a positive electrode active material layer including a positive electrode active material and disposed on the positive electrode current collector plate;
A negative electrode plate having a negative electrode current collector plate, and a negative electrode active material layer that includes a negative electrode active material and is disposed on the negative electrode current collector plate;
A separator interposed between the positive electrode plate and the negative electrode plate,
A lithium ion secondary battery in which the positive electrode active material layer and the negative electrode active material layer face each other through the separator,
The negative electrode active material layer is
A facing portion facing the positive electrode active material layer via the separator;
A method for recovering the capacity of a lithium ion secondary battery comprising: a non-facing portion in which the positive electrode active material layer facing through the separator does not exist;
A method for recovering the capacity of a lithium ion secondary battery in which the lithium ion secondary battery is left in a temperature environment of 45 ° C. or higher and 65 ° C. or lower and subjected to a leaving treatment. The capacity recovery method for a lithium ion secondary battery according to claim 1,
The neglect treatment is
A method for recovering the capacity of a lithium ion secondary battery, wherein the lithium ion secondary battery is left in a state where the SOC is 30% or less. A capacity recovery method for a lithium ion secondary battery according to claim 1 or 2,
The neglect treatment is
Lithium ion secondary battery in which the lithium ion secondary battery is left in a state where the battery voltage of the lithium ion secondary battery is lower than the battery voltage value at which the lithium ion secondary battery has SOC 0% by discharging. Battery capacity recovery method. It is the capacity | capacitance recovery method of the lithium ion secondary battery as described in any one of Claims 1-3,
The neglect treatment is
A method for recovering the capacity of a lithium ion secondary battery, wherein the lithium ion secondary battery is left for 4 hours or longer.

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