JP4929763B2 - Lithium secondary battery - Google Patents

Description

  The present invention relates to a lithium secondary battery, and in particular, a negative electrode having a negative electrode active material layer including at least one selected from the group consisting of Si simple substance, Sn simple substance, Si oxide, Sn oxide, Si alloy and Sn alloy. The present invention relates to a provided lithium secondary battery.

  In recent years, with the development of portable devices such as personal computers and mobile phones, the demand for batteries as power sources has increased. A battery used for the above applications is required to be used at room temperature, and at the same time, a high energy density and excellent cycle characteristics are required.

  In response to this requirement, new high capacity active materials have been developed for each of the positive electrode and the negative electrode, and in particular, a solution by using a negative electrode active material of a simple substance of Si or Sn, an oxide, or an alloy that can obtain a very high capacity. Is going to be planned.

  At that time, the problem is the fine powdering of the negative electrode active material that accompanies charging and discharging, and there has been a concern that the negative electrode active material particles lose their current collecting ability and the cycle characteristics deteriorate as charging and discharging are repeated. In order to solve this problem, a technique is disclosed in which an amorphous Si thin film is used as a negative electrode active material to improve current collection and suppress deterioration of cycle characteristics (see, for example, Patent Document 1).

In addition, when metallic lithium is used as the negative electrode, a buffer gap is provided between the negative electrode surface and the separator as a means of preventing damage to the separator and abnormal precipitation of lithium, suppressing internal short circuit and solving cycle deterioration. A technique is disclosed (for example, see Patent Document 2).
JP 2002-83594 A Japanese Patent Laid-Open No. 10-12279

  However, since the negative electrode active material of a simple substance of Si, an oxide or an alloy has a large expansion / contraction due to charge / discharge, even an amorphous Si thin film used as a negative electrode active material in Patent Document 1 is charged / discharged. As the process is repeated, the negative electrode current collector is greatly deformed and wrinkles or breaks, so that the capacity of the cycle characteristics is likely to decrease.

  In order to reduce the adverse effect due to the expansion of the negative electrode active material, a new problem arises when the technique described in Patent Document 2 is applied. That is, the positive electrode active material in the facing portion of the spacer (insulating structure member) for providing the buffer gap cannot participate in the charge / discharge reaction because there is no negative electrode active material facing it, resulting in a capacity loss.

  Further, in the vicinity of the positive electrode active material where there is no opposing negative electrode in this way, an active material that has been charged and an active material that is not so are adjacent to each other, so that it is easy to make a local battery. In this case, lithium diffusion may occur from the positive electrode active material that has not been charged to the active material that has been charged. When lithium is diffused, a part of the positive electrode active material facing the negative electrode is already supplied with lithium before the lithium returns from the negative electrode. Therefore, during discharge, lithium released by charging returns into the positive electrode active material. In other words, the charge / discharge capacity is reduced and the cycle characteristics are remarkably deteriorated.

  The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a lithium secondary battery capable of preventing capacity loss and cycle characteristic deterioration.

In order to solve the conventional problems, the lithium secondary battery of the present invention is
Selected from the group consisting of a negative electrode current collector and Si simple substance, Sn simple substance, Si oxide, Sn oxide, Si alloy and Sn alloy that occlude / release lithium ions formed on a part of the surface of the negative electrode current collector A negative electrode active material layer containing at least one or more of
A positive electrode having a positive electrode current collector, and a positive electrode active material layer containing an active material capable of inserting and extracting lithium ions on a portion of the surface of the positive electrode current collector;
A lithium secondary battery having a separator disposed between a negative electrode and a positive electrode,
A space holding member is formed between the exposed portion of the negative electrode current collector and the separator,
The space holding member is arranged to face the exposed portion of the positive electrode current collector.

  With this configuration, a space necessary for expanding and contracting the negative electrode active material can be secured in advance by the space holding member, so that deterioration of cycle characteristics can be prevented.

  According to the lithium secondary battery of the present invention, since the space necessary for the expansion and contraction of the negative electrode active material can be secured in advance by the space holding member, it is possible to prevent deterioration of cycle characteristics. In addition, the space holding member is formed between the exposed portion of the negative electrode current collector and the separator, and is disposed opposite to the exposed portion of the positive electrode current collector, thereby inhibiting the reaction of the positive and negative electrode active materials. There is no.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following contents as long as it is based on the basic features described in this specification.

(Embodiment 1)
The lithium secondary battery of the present invention will be described.

  FIG. 1 is a schematic cross-sectional view of a stacked lithium secondary battery according to the first embodiment. In FIG. 1, a lithium secondary battery 10 includes a positive electrode 1, a negative electrode 2 that opposes the positive electrode 1 and occludes lithium ions during charging and releases lithium ions during discharging, and a separator 3 interposed between the positive electrode 1 and the negative electrode 2. And an electrolyte (not shown) that conducts lithium ions impregnated in the separator 3. The positive electrode 1 and the negative electrode 2 are accommodated in the case 4 together with the separator 3 and the electrolyte. The negative electrode 2 includes a negative electrode current collector 21 and a negative electrode active material layer 22 formed on a part of the surface of the negative electrode current collector 21. On the surface of the negative electrode current collector 21, a space holding member 23 that secures a space between the exposed portion where the negative electrode active material layer 22 is not formed and the separator 3 is disposed. The positive electrode 1 includes a positive electrode current collector 11 and a positive electrode active material layer 12 formed on a part of the surface of the positive electrode current collector 11. The space holding member 23 is disposed on the surface of the positive electrode current collector 11 so as to face an exposed portion where the positive electrode active material layer 12 is not formed.

  Since the space holding member 23 is disposed on the exposed portion of the negative electrode current collector 21 where the negative electrode active material layer 22 is not formed, the space holding member 23 does not face the negative electrode active material layer 22. All can participate in charge / discharge reactions. Further, since the space holding member 23 is disposed on the surface of the positive electrode current collector 11 so as to face the exposed portion where the positive electrode active material layer 12 is not formed, the space holding member 23 does not face the positive electrode active material layer 12. All layers 12 can participate in the charge / discharge reaction. Therefore, the negative electrode active material layer 22 and the positive electrode active material layer 12 are uniformly charged and discharged. Accordingly, good cycle characteristics are exhibited.

  The width of the space holding member 23 is arbitrary, but is preferably 10 μm or more and 1 cm or less in consideration of holding the energy density. Although the thickness of the space holding member 23 is also arbitrary, the short-circuit between the negative electrode 2 and the positive electrode 1 due to expansion of the negative electrode active material layer 22 during charging is suppressed, and the positive electrode 1 and the negative electrode 2 are sufficiently connected via the separator 3. It is preferable that the thickness be in close contact.

  In addition, the space holding member 23 needs at least two places in order to form a space. For example, when the negative electrode current collector 21 is a rectangular parallelepiped, as shown in FIG. 1, a space holding member 23 is required in a part or the whole in the vicinity of two opposing sides on the same surface.

  Although FIG. 1 shows the case of a stacked battery, in the case of a battery configuration in which both surfaces of the positive electrode 1 are opposite to the negative electrode 2, such as a cylindrical battery or a rectangular battery having a spiral electrode group. Can have a configuration in which the active material layer 22 and the space holding member 23 are provided on both sides of the negative electrode 2 facing each other, and the positive electrode active material layer 12 is provided on both sides of the positive electrode 1 facing each other.

  The negative electrode active material layer 22 is a negative electrode including at least one selected from the group consisting of Si simple substance, Sn simple substance, Si oxide, Sn oxide, Si alloy, and Sn alloy as an active material that occludes and releases lithium. It has an active material layer. More specifically, Si, Sn and their alloys, oxides, etc. may be crystalline or amorphous.

  The space holding member 23 can be used as long as it does not react electrochemically or chemically with lithium ions and electrolyte. Examples thereof include a polymer material, a metal material, an oxide, a nitride material, and a carbon material. It is preferable that the space holding member 23 is a porous body. This is to facilitate electrolyte injection. In the case of not being a porous body, even if the space holding member 23 has a hole portion such as a through hole in the part, the same effect as in the case of the porous body can be obtained.

  The negative electrode current collector 21 may be an electron conductor that is substantially chemically stable in the configured negative electrode 2. For example, copper (Cu), nickel (Ni), titanium (Ti), etc. can be generally used as a material.

The positive electrode active material layer 12 can be made of a material generally known as a positive electrode active material for a lithium secondary battery, such as lithium cobalt oxide LiCoO ₂ .

  As the positive electrode current collector 11, aluminum (Al), Al alloy, Ni, Ti, or the like can be generally used.

For the electrolyte, the separator 3 and the case 4, all materials and shapes used for a battery generally constituted by applying a lithium compound or a lithium alloy to an electrode active material can be applied.
(Embodiment 2)
FIG. 2 is a schematic cross-sectional view of the stacked lithium secondary battery according to the second embodiment. In FIG. 2, the same components as those in FIG.

  In FIG. 2, the lithium secondary battery 20 includes a space holding facing member 13 that secures a space between the exposed portion where the positive electrode active material layer 12 is not formed and the separator 3 on the surface of the positive electrode current collector 11. The configuration is the same as that of the lithium secondary battery 10 of Embodiment 1 except that the space holding member 23 and the space holding facing member 13 are opposed to each other with the separator 3 interposed therebetween.

  Since the space holding member 23 is disposed on the exposed portion of the negative electrode current collector 21 where the negative electrode active material layer 22 is not formed, the space holding member 23 does not face the negative electrode active material layer 22. All can participate in charge / discharge reactions. Further, since the space holding facing member 13 is disposed on the exposed portion where the positive electrode active material layer 12 is not formed on the surface of the positive electrode current collector 11, the space holding facing member 13 does not face the positive electrode active material layer 12. All layers 12 can participate in the charge / discharge reaction. Therefore, the negative electrode active material layer 22 and the positive electrode active material layer 12 are uniformly charged and discharged. Accordingly, good cycle characteristics are exhibited.

  Also in the second embodiment, the widths of the space holding member 23 and the space holding facing member 13 are preferably 10 μm or more and 1 cm or less in consideration of physical strength and the like while maintaining energy density.

  Although the thickness of the space holding member 23 and the space holding counter member 13 is arbitrary, a short circuit between the negative electrode 2 and the positive electrode 1 due to expansion of the negative electrode active material layer 22 during charging is suppressed, and the positive electrode 1 and the negative electrode 2 are separated from each other. It is preferable that the thickness be sufficiently close to each other via 3.

  In addition, the space holding member 23 and the space holding facing member 13 each need at least two places in order to form a space. Considering the maintenance of strength, the space holding member 23 and the space holding facing member 13 are required in part or in whole so that they can face the same place.

  Although FIG. 2 shows the case of a stacked battery, in the case of a battery configuration in which both surfaces of the positive electrode 1 are opposed to the negative electrode 2, such as a cylindrical battery or a rectangular battery having a spiral electrode group. Can be configured such that the negative electrode active material layer 22 and the space holding member 23 are provided on both surfaces of the negative electrode 2 facing each other, and the positive electrode active material layer 12 and the space holding and facing member 13 are provided on both surfaces of the positive electrode 1 facing each other.

  The space holding facing member 13 can be used as long as it does not react electrochemically or chemically with lithium ions and electrolyte. Examples thereof include a polymer material, a metal material, an oxide, a nitride material, and a carbon material. It is preferable that the space holding facing member 13 is a porous body. This is to facilitate electrolyte injection. In the case of not being a porous body, the same effect as in the case of a porous body can be obtained even if a part of the space holding facing member 13 has a hole portion such as a through hole.

Further, the space holding member 23 and the space holding facing member 13 have a concave structure or a convex structure, and a convex structure or a concave structure, respectively, and are formed so as to be fitted via the separator 3 as shown in FIG. Preferably it is. This is because not only the positioning of the positive electrode 1 and the negative electrode 2 is facilitated but also the positional holding between the positive electrode 1 and the negative electrode 2 is eliminated, so that the space holding member 23 faces the positive electrode active material layer 12. It is possible to suppress the occurrence of capacity loss. The uneven structure may be any shape that can be fitted. For example, there are a rectangular shape, a triangular shape, a circular diameter shape, and the like.
Although FIG. 2 shows the case of a stacked battery, in the case of a battery configuration in which both surfaces of the positive electrode 1 are opposed to the negative electrode 2, such as a cylindrical battery or a rectangular battery having a spiral electrode group, A configuration in which the active material layer 22 and the space holding member 23 are provided on both surfaces facing the negative electrode 2 and the active material layer 12 and the space holding facing member 13 are provided on both surfaces facing the positive electrode 1 is preferable.

  The materials that can be used in each configuration are the same as those in the first embodiment.

  Hereinafter, the embodiments of the present invention will be described in more detail by way of specific examples. In addition, this invention is not limited to the Example shown below.

Example 1
The negative electrode active material layer 22 and the space holding member 23 were formed on the negative electrode current collector 21 made of copper foil as follows.

In Example 1, a case where lithium cobaltate (LiCoO ₂ ) is used as a positive electrode active material and a SiO _x (x = 0 to 1.0) thin film is used as a negative electrode active material as a lithium secondary battery will be described.

  In Example 1, a negative electrode and an aluminum laminate battery were prepared in the following manner, and their cycle life and discharge capacity were evaluated.

(1) Manufacture of negative electrode Samples 1 to 4 shown in Table 1 using a vapor deposition apparatus 30 (manufactured by ULVAC, Inc.) having an electron beam (EB) heating means (not shown) as shown in FIG. A negative electrode 2 was prepared. The vapor deposition apparatus 30 includes a gas pipe (not shown) for introducing oxygen gas into the chamber 31 and a nozzle 32. The nozzle 32 was connected to a pipe 33 introduced into the vacuum chamber 31. The pipe 33 was connected to an oxygen cylinder via a mass flow controller. From the nozzle 32, oxygen gas with a purity of 99.7% (manufactured by Nippon Oxygen Co., Ltd.) was released at a flow rate of 0 to 150 sccm. A fixing base 34 for fixing the negative electrode current collector 21 was installed above the nozzle 32. A target 35 that is deposited in a columnar shape on the surface of the negative electrode current collector 21 was installed vertically below the fixed base 34. As the target 35, a simple substance of 99.9999% silicon (manufactured by Kojundo Chemical Laboratory Co., Ltd.) was used. The negative electrode current collector 21 was covered with a metal mask so that a negative electrode active material layer 22 having a size of 30 mm × 30 mm could be formed.

  The acceleration voltage of the electron beam applied to the silicon target 35 was set to -8 kV, and the emission was set to 500 mA. After passing through the oxygen atmosphere, the vapor of silicon alone was deposited on the copper foil placed on the fixed base 34 to form the negative electrode active material layer 22 made of a compound containing silicon and oxygen. The deposition time was set to 1 to 2.5 hours. The negative electrode thus obtained is referred to as negative electrode 1A.

  The amount of oxygen contained in the obtained negative electrode active material layer 22 was quantified by a combustion method. In the combustion method, the amount of oxygen is extracted by an inert gas-impulse heating and melting method, which is thermal decomposition at high temperature, and the amount of silicon is inductively coupled with a high-sensitivity non-dispersive infrared detector as CO gas. It was measured by (ICP spectroscopy). According to this method, the composition of the composition was as shown in Table 1.

  As the current collector sheet, an electrolytic Cu foil (manufactured by Furukawa Circuit Foil Co., Ltd., thickness 35 μm, size 40 mm × 40 mm, with lead portion of 5 mm × 10 mm) was used.

  When X-ray diffraction analysis was performed on these thin films, a crystalline peak attributed to Cu as a current collector sheet was observed, and a broad peak at a position of 2θ = 15-40 ° in any thin film. Was detected.

  From this result, it was found that the active material was amorphous. The thickness of the negative electrode active material layer was as shown in Table 1, respectively.

  The negative electrode was again introduced into the vacuum vapor deposition apparatus, and then a metal Li target (manufactured by Honjo Chemical Co., Ltd.) was vapor-deposited on the negative electrode by resistance heating. The deposition amount was changed by changing the deposition time, and lithium was added on the negative electrode surface so as to supplement the irreversible capacity of each sample.

  After vapor deposition, an adhesive tape (base material: polypropylene, acrylic adhesive) (samples 1 to 4) having a thickness of 110 μm, a length of 40 mm, and a width of 3 mm as a space holding member 23 on the negative electrode current collector 21 of each sample (samples 1 to 4). It was formed so as to surround the active material layer 22.

  Moreover, in order to compare with the characteristics of Samples 1 to 4, Comparative Sample 1 in which the space holding member 23 was not formed was produced.

  After the negative electrode 2 was prepared, vacuum drying was performed at 100 ° C. for 10 hours, and then stored at room temperature in a dry atmosphere with a dew point of −60 ° C. or less. The moisture in the electrode was dehydrated and controlled by storing.

  Moreover, the thickness at the time of charge of the active material layer 22 was confirmed by measuring the film thickness after charging with a constant current in a battery cell using the active material layer 22 as a working electrode and Li metal as a counter electrode in advance.

(2) Production of positive electrode LiCoO ₂ which is a positive electrode active material was synthesized by mixing Li ₂ CO ₃ and CoCO ₃ at a predetermined molar ratio and heating at 950 ° C., and this was made into a size of 45 μm or less. What was classified was used. To 100 parts by weight of the positive electrode active material, 5 parts by weight of acetylene black as a conductive agent, 4 parts by weight of polyvinylidene fluoride as a binder, and an appropriate amount of N-methyl-2-pyrrolidone as a dispersion medium are added and mixed thoroughly. A positive electrode mixture paste was obtained.

The positive electrode mixture paste was applied to a current collector made of an aluminum foil having a thickness of 15 μm (manufactured by Showa Denko KK), dried, rolled, cut into a size of 50 mm × 50 mm (5 mm × 10 mm with a lead portion), and then the negative electrode The positive electrode mixture was peeled off with a width of 10 mm so as to face the active material layer 22, and the positive electrode active material layer 12 having a thickness of 75 μm and a size of 30 mm × 30 mm was produced.
. As a result, a positive electrode 1 including a positive electrode current collector 11 and a positive electrode active material layer 12 carried on the current collector was obtained.

  The positive electrode was stored at room temperature in a dry atmosphere with a dew point of −60 ° C. or lower, and the moisture in the electrode was dehydrated by vacuum drying at 80 ° C. immediately before the battery was constructed as described below.

(3) Production of Aluminum Laminate Type Lithium Secondary Battery Next, in order to evaluate the cycle characteristics in the batteries using Samples 1-4 and Comparative Sample 1 produced as described above, the aluminum laminate type lithium secondary battery shown in FIG. A secondary battery was produced.

The positive electrode 1 and the negative electrode 2 are insulated by a commercially available separator 3 of a polyethylene microporous film having a porosity of about 40% and a thickness of 20 μm, so that the positive electrode 1 and the negative electrode 2 are not misaligned. Then, the lead part was taken out and sealed all except the liquid injection port. Both ends were fixed to the negative electrode current collector 21 with an adhesive tape so that the separator 3 did not loosen during insertion. In the electrolyte 4, ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 1: 1, and a solution prepared by dissolving 1.0 mol / L of LiPF ₆ in the mixture was injected from the injection port. Thereafter, the liquid inlet was sealed while reducing the vacuum, and an aluminum laminated lithium secondary battery was produced.

(4) Charging / discharging cycle test evaluation Next, each said battery was accommodated in the thermostat of 20 degreeC, and the charging / discharging cycle test was done. At that time, the current value that discharges the design capacity in 1 hour, that is, the constant current charge until the battery voltage reaches 4.2V at an hour rate, then switches to the constant voltage charge of 4.2V, the current value is constant current charge The battery was charged until it dropped to 5% of the value. Further, at the time of discharging, re-constant current discharging was performed until the battery voltage reached 2.5 V at the same current value as that during constant current charging and at a current value of 5 hours every 20 cycles, and the capacity was measured. In this way, the ratio of the discharge capacity during the cycle to the initial discharge capacity, that is, the change in the capacity maintenance rate, was examined, and the capacity maintenance rate of the constant current discharge at the 5-hour rate after 100 cycles was compared between the samples. The value in parentheses is the capacity maintenance rate of constant current discharge at 1 hour rate.

  FIG. 4 shows the relationship between the capacity retention ratio and the number of cycles (cycle characteristics) between the battery of sample 1 and the battery of comparative sample 1. As is clear from FIG. 4, in the comparative sample 1 in which the space holding member 23 does not exist, the capacity maintenance rate was lowered early. On the other hand, in the battery of sample 1 in which the space holding member 23 is formed, the cycle characteristics are remarkably improved as compared with the comparative sample 1.

  Table 2 shows the capacity retention rate after 100 cycles and the presence or absence of wrinkles. The wrinkles here were observed from an X-ray CT cross-sectional image of the battery, and when the maximum unevenness of the negative electrode 2 was 0.1 mm or more, it was determined that there were wrinkles. In Comparative Sample 1 without the space holding member 23, wrinkles were generated when the capacity retention rate at a 5-hour rate was about 60%. On the other hand, the batteries of Samples 1 to 4 in which the space holding member 23 was formed did not show wrinkles even after 100 cycles, and maintained a capacity maintenance rate at a 5-hour rate of approximately 80% or more, and an excellent cycle. The characteristics are shown.

Such an improvement in the capacity retention rate has improved cycle characteristics by having the space holding member 23. Although the adhesive tape is used this time, a metal foil such as Cu foil or a porous film such as Al ₂ O ₃ may be used.

(Example 2)
Next, the result when the space holding counter member 13 is formed on the positive electrode 1 is shown. Here, a case where SiO _0.3 is applied to the negative electrode active material layer 22 will be described as an example (Sample 5).

  Adhesive tape (base material: polypropylene, acrylic adhesive, rectangular cut with a width of 3 mm and a depth of 30 μm at the center in the width direction) is formed on the positive electrode current collector 11 with a thickness of 75 μm, a length of 40 mm, and a width of 7 mm. A space holding counter member 13 was formed by pasting the active material layer 12 so as to surround it. The space holding member 13 is disposed so as to face the center portion in the width direction so as to match that of the space holding member 10. Other conditions were in accordance with Sample 2.

  Using these samples, batteries were prepared and evaluated in the same manner as Sample 2. Table 3 shows the capacity retention rate of constant current discharge at 5 hours after 100 cycles and the presence or absence of soot. The value in parentheses is the capacity maintenance rate of constant current discharge at 1 hour rate.

  As shown in Table 3, the sample 5 in which the space holding member 23 and the space holding counter member 13 are formed does not show wrinkles even after 100 cycles, and the capacity maintenance rate at a 5-hour rate of about 80% or more and 1 of about 80%. The capacity retention rate at the time rate was maintained, and excellent cycle characteristics were exhibited.

  Such an improvement in the capacity retention rate has improved the cycle characteristics by having the space holding member 23 and the space holding facing member 13.

  In this example, Si was used as a simple substance and an oxide, but an Si alloy, a Sn simple substance, an oxide, or an alloy may be used.

  In the lithium secondary battery according to the present invention, a space holding member is formed between the negative electrode current collector and the separator, and the space holding member is disposed to face the positive electrode current collector of the positive electrode. In this lithium secondary battery, cycle characteristics can be greatly improved in a negative electrode having a large expansion, such as a simple substance, oxide or alloy of Si or Sn that occludes and releases lithium.

Schematic sectional view showing the configuration of the lithium secondary battery according to Embodiment 1 of the present invention. Schematic sectional view showing the configuration of the lithium secondary battery according to Embodiment 2 of the present invention. Schematic which shows the vapor deposition apparatus used for preparation of the negative electrode active material layer in the Example of this invention The figure which shows the capacity | capacitance maintenance factor of the lithium secondary battery in embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Electrolyte 4 Case 10, 20 Lithium secondary battery 21 Negative electrode collector 22 Negative electrode active material layer 23 Space holding member 11 Positive electrode current collector 12 Positive electrode active material layer 13 Space holding opposing member 30 Vapor deposition apparatus 31 Chamber 32 Nozzle 33 Piping 34 Fixed base 35 Target

Claims (7)

Selected from the group consisting of a negative electrode current collector and Si simple substance, Sn simple substance, Si oxide, Sn oxide, Si alloy and Sn alloy that occlude / release lithium ions formed on a part of the surface of the negative electrode current collector A negative electrode active material layer containing at least one kind of
A positive electrode having a positive electrode current collector, and a positive electrode active material layer containing a positive electrode active material capable of inserting and extracting lithium ions formed on a portion of the surface of the positive electrode current collector;
A separator disposed between the negative electrode and the positive electrode;
In a lithium secondary battery having
A space holding member is formed between the exposed portion of the negative electrode current collector and the separator,
The space holding member is disposed opposite to the exposed portion of the positive electrode current collector;
Rechargeable lithium battery.   The lithium secondary battery according to claim 1, wherein a width of the space holding member is 10 μm or more and 1 cm or less.   The lithium secondary battery according to claim 1, wherein a space holding facing member is formed between the exposed portion of the positive electrode current collector and the separator. The space holding member has a concave structure or a convex structure;
The space holding facing member has a convex structure or a concave structure;
The space holding member and the space holding facing member are formed so as to be fitted via a separator,
The lithium secondary battery according to claim 3.   5. The lithium secondary battery according to claim 3, wherein a width of the space holding facing member is 10 μm or more and 1 cm or less.   6. The lithium secondary battery according to claim 1, wherein at least one of the space holding member and the space holding facing member is a porous body.   6. The lithium secondary battery according to claim 1, wherein at least one of the space holding member and the space holding facing member has a through hole.