JP2012164571A - Negative electrode body and lithium ion battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a negative electrode body capable of preventing alloying between Li and Al when a negative electrode collector comprising an Al-containing material is used; and a lithium ion battery including the negative electrode body.SOLUTION: A negative electrode body 1 used in a lithium ion battery 100 includes: a negative electrode collector 11 comprising Al or an Al alloy; a negative electrode layer 12 including mixed powder of a negative electrode active material particle and a sulfide solid electrolyte particle; and an alloying prevention layer 13 interposed between the negative electrode collector 11 and the negative electrode layer 12 and preventing alloying between Li and Al. The alloying prevention layer 13 has an electron conductivity of 10S/m or more and comprises a material which is not reactive with sulfide.

Description

  The present invention relates to a negative electrode body suitable for a lithium ion battery, and a lithium ion battery using the negative electrode body.

  Lithium batteries and lithium ion secondary batteries (hereinafter simply referred to as lithium ion batteries) using lithium ion transfer reactions between the positive and negative electrode bodies are used as power sources for relatively small electrical devices such as portable devices. Yes.

  This lithium ion battery includes a positive electrode body, a negative electrode body, and an electrolyte layer disposed between these electrode bodies. Each electrode body further includes a current collector having a current collecting function and an electrode layer containing an active material. And it is a secondary battery of the system which performs charging / discharging by lithium (Li) ion moving through an electrolyte layer between a positive electrode body and a negative electrode body. In recent years, an all-solid battery using an inorganic solid electrolyte instead of an organic electrolyte has been proposed (see, for example, Patent Document 1).

Examples of the lithium ion battery include those described in Patent Document 1. A positive electrode body in which a positive electrode layer is formed by an electron beam evaporation method using LiCoO ₂ as a raw material on a positive electrode current collector made of stainless steel foil, and a negative electrode made by bonding a stainless steel foil on a negative electrode layer made of Li metal film A negative electrode body on which a current collector is formed and a solid electrolyte layer made of Li ₂ SP ₂ S ₅ are described. As described in Patent Document 1, stainless steel, Cu, or the like is generally used for the negative electrode current collector.

JP 2009-259696 A JP 2005-259682 A

  As the negative electrode current collector, use of a material containing Al as a material that is more flexible, easier to handle, and less expensive than the material described in Patent Document 1 has been studied. However, when a material containing Al is used as the negative electrode current collector, Li and Al react due to contact with the Li precipitate produced on the negative electrode current collector by repeated charge and discharge of the lithium ion battery. And alloyed. Since the Li-Al alloy is brittle in crystals and pulverized, there is a risk of cracking due to volume expansion and contraction during charging and discharging of the battery. If the contact area between the negative electrode current collector and the negative electrode layer decreases along with this cracking, a high resistance layer is formed, which causes a decrease in battery characteristics.

  As an example of using a material containing Al as a current collector, Patent Document 2 discloses a current collector in which an oxide film layer is formed on the surface of a positive electrode current collector made of Al in order to prevent Al erosion by Al. The body is listed. However, even if an oxide film layer is formed on the surface of a negative electrode current collector made of a material containing Al, since this oxide film layer is an insulator, it may become a high resistance layer and reduce battery characteristics.

  The present invention has been made in view of the above circumstances, and one of its purposes is a negative electrode body used for a lithium ion battery, and a negative electrode current collector made of a material containing Al (Al or Al alloy) Is to provide a negative electrode body capable of preventing alloying of Li and Al. Another object of the present invention is to provide a lithium ion battery using the negative electrode body of the present invention.

  The present invention is provided with a Li-Al alloying prevention layer (hereinafter simply referred to as an alloying prevention layer) for preventing alloying of Li and Al between the negative electrode current collector and the negative electrode layer. Achieve the goal.

(1) The negative electrode body of the present invention is a negative electrode body used for a lithium ion battery, and includes a negative electrode current collector made of Al or an Al alloy, and a mixed powder of negative electrode active material particles and sulfide solid electrolyte particles. A negative electrode layer; and an alloying prevention layer interposed between the negative electrode current collector and the negative electrode layer to prevent alloying of Li and Al. The alloying prevention layer is made of a material having an electron conductivity of 10 ⁶ S / m or more and does not react with sulfide.

According to this configuration, since the alloying prevention layer is provided between the negative electrode current collector and the negative electrode layer, Li ions can be prevented from reaching the negative electrode current collector through the negative electrode layer. It is possible to prevent Li from being deposited on the negative electrode current collector by repeating the charging and discharging. Therefore, even if a material containing Al is used as the negative electrode current collector, it is possible to prevent Al from coming into contact with Li precipitates, so that Li and Al can be prevented from reacting and alloying. Formation of the high resistance layer on the electric body can be prevented. Here, in order to effectively prevent Li ions from reaching the negative electrode current collector through the negative electrode layer, the Li ion conductivity of the alloying prevention layer is preferably 10 ⁻⁸ S / m or less, More preferably, it is substantially zero.

The anti-alloying layer has an electron conductivity of 10 ⁶ S / m or more, so that it allows sufficient electron conduction between the negative electrode layer and the negative electrode current collector, and is sufficient for charging and discharging a lithium ion battery. It is possible to stably secure the current collection of the electrode body.

  In the present invention, since the negative electrode layer includes a mixed powder of negative electrode active material particles and sulfide solid electrolyte particles, the negative electrode layer has a structure in which sulfide solid electrolyte particles exist around the negative electrode active material particles. . Since the sulfide solid electrolyte particles mediate the conduction of Li ions in the negative electrode layer, the exchange of Li ions can be performed stably. A sulfide solid electrolyte is preferable because it generally exhibits higher Li ion conductivity than that of an oxide. Since the negative electrode layer contains sulfide solid electrolyte particles, the alloying prevention layer is made of a material that does not react with sulfide, thereby suppressing the reaction between the negative electrode current collector and the sulfide and changing the material of the negative electrode current collector. It can prevent and discoloration of the negative electrode current collector accompanying it can be prevented. Therefore, embrittlement of the negative electrode current collector can be prevented and the function as the current collector can be maintained.

  As described above, since an alloying prevention layer is interposed between the negative electrode current collector and the negative electrode layer, alloying of Li and Al can be prevented, so that the material containing Al in the negative electrode current collector (Al or Al alloy) can be used. The material containing Al is more flexible and less expensive than stainless steel, which has been used as a constituent material of negative electrode current collectors in the past, so the negative electrode body can be handled relatively easily and the cost can be reduced. I can plan.

  (2) As one form of the negative electrode body of the present invention, the alloying prevention layer may be made of a material mainly composed of a carbon material.

  Since the carbon material has the above-described electronic conductivity and the property of not reacting with sulfide, it can be suitably used as an alloying prevention layer. As described later, there are various specific materials for the carbon material. Among these various carbon materials, it is preferable to use graphite. The alloying prevention layer is mainly composed of one or more kinds selected from various carbon materials, and may additionally contain a conductive material.

  (3) As one form of the negative electrode body of the present invention, the negative electrode active material particles may be made of the same material as the carbon material constituting the alloying prevention layer.

  According to this configuration, the same material improves the adhesion between the alloying prevention layer and the negative electrode layer. Therefore, cracks or the like are hardly generated at the bonding interface between the alloying prevention layer and the negative electrode layer, and the formation of the high resistance layer can be further prevented.

  (4) As one form of the negative electrode body of the present invention, the alloying prevention layer has a thickness of 10 to 50 μm.

  By setting the thickness of the alloying prevention layer to 10 μm or more, a sufficient interval between the negative electrode current collector and the negative electrode layer can be ensured, and Li and Al can be prevented from reacting and alloying. The formation of the high resistance layer on the negative electrode current collector can be prevented. On the other hand, if the thickness of the alloying prevention layer is too thick, it is difficult to reduce the size of the negative electrode body, so the upper limit is preferably 50 μm or less.

  (5) The lithium ion battery of the present invention is a lithium ion battery comprising a positive electrode body, a negative electrode body, and a solid electrolyte layer disposed between the two electrode bodies. It is characterized by using the body.

  If it is a lithium ion battery provided with the said structure, it is excellent in a battery characteristic. As described in the description of the negative electrode body, this can prevent Li and Al from reacting and alloying by the anti-alloying layer provided in the negative electrode body to be used. This is because the formation of the resistance layer can be prevented.

  The negative electrode body of the present invention can prevent Li ions from reaching the negative electrode current collector through the negative electrode layer by interposing an alloying prevention layer between the negative electrode current collector and the negative electrode layer. Even when a material containing Al (Al or Al alloy) is used for the current collector, Li and Al can be prevented from reacting and alloying, and formation of a high resistance layer on the negative electrode current collector can be prevented. . By using a negative electrode current collector made of a material containing Al, it is relatively easy to handle the negative electrode body, and costs can be reduced.

  Since the lithium ion battery of the present invention uses the negative electrode body of the present invention, the battery characteristics are excellent.

It is a schematic block diagram of the lithium ion battery which concerns on embodiment. FIG. 2 is a schematic configuration diagram showing a state before the lithium ion battery shown in FIG. 1 is assembled.

  Hereinafter, embodiments of the negative electrode body of the present invention will be described. The negative electrode body of the present invention can be used as the negative electrode body 1 of a lithium ion battery 100 as shown in FIG. In addition to the negative electrode body 1, the lithium ion battery 100 includes a positive electrode body 2 and a solid electrolyte layer (SE layer) 3, and exchanges Li ions between the negative electrode body 1 and the positive electrode body 2. It functions as a battery. Hereinafter, each configuration of the lithium ion battery 100 will be described in detail with a focus on the configuration of the negative electrode body 1.

[Negative electrode body]
The negative electrode body 1 of the present invention includes a negative electrode current collector 11 made of Al or an Al alloy, a negative electrode layer 12, and an alloying prevention layer 13 interposed between the negative electrode current collector 11 and the negative electrode layer 12. Prepare.

(Negative electrode current collector)
The negative electrode current collector 11 collects current of a negative electrode layer 12 described later. The negative electrode current collector 11 is a conductive material, and one feature of the present invention is to use a material made of Al or an Al alloy. Al or Al alloy has the characteristics of being soft and light, is relatively easy to handle, and can reduce costs compared to conventionally used stainless steel and the like.

(Negative electrode layer)
The negative electrode layer 12 is a layer obtained by pressure molding a mixed powder of negative electrode active material particles and sulfide solid electrolyte particles. The negative electrode active material particles are composed of a negative electrode active material that is a main component of the battery reaction. As the negative electrode active material, a C, Si, Ge, Sn, Al, Li alloy, or an oxide containing Li such as Li ₄ Ti ₅ O ₁₂ can be used. A preferable average particle diameter of the negative electrode active material particles is 1 to 15 μm. The sulfide solid electrolyte particles are composed of a sulfide solid electrolyte having high Li ion conductivity, and are necessary for mediating the conduction of Li ions in the negative electrode layer 12. Examples of sulfide-based solid electrolytes include Li ₂ SP ₂ S ₅ system, Li ₂ S-SiS ₂ system, Li ₂ SB ₂ S ₃ system, and P ₂ O ₅ and Li ₃ PO ₄ are added. Also good. A preferable average particle diameter of the sulfide solid electrolyte particles is 1 to 5 μm.

  The negative electrode layer 12 may contain a conductive additive and a binder (binder) as necessary, in addition to the mixed powder of the negative electrode active material particles and the sulfide solid electrolyte particles. Examples of the conductive assistant include carbon black such as acetylene black (AB) and ketjen black (KB). Examples of the binder include polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF).

  The mixing ratio of the negative electrode active material particles and the sulfide solid electrolyte particles in the negative electrode layer may cause a decrease in battery capacity when the ratio of the negative electrode active material particles to the entire negative electrode layer decreases. On the other hand, if the ratio of the negative electrode active material particles to the entire negative electrode layer becomes too large, the ratio of the sulfide solid electrolyte particles and the like is relatively reduced, and it becomes difficult to mediate the conduction of Li ions in the negative electrode layer, resulting in an internal resistance. There is a possibility that it may increase or the binding property may decrease. Therefore, preferable mixing ratios of the negative electrode active material particles and the sulfide solid electrolyte particles in the negative electrode layer are negative electrode active material particles: 40 to 60% by mass and sulfide solid electrolyte particles: 40 to 60% by mass.

(Alloy prevention layer)
The alloying prevention layer 13 reacts with a precipitate of Li generated on the negative electrode current collector 11 by repetition of charge and discharge of the lithium ion battery, and Al or an Al alloy applied to the negative electrode current collector 11, This is a layer for preventing Li and Al from alloying. By interposing the alloying prevention layer 13 between the negative electrode current collector 11 and the negative electrode layer 12, Li ions can be prevented from reaching the negative electrode current collector 11 via the negative electrode layer 12, Formation of Li precipitates can be suppressed. Therefore, it is possible to prevent Al from coming into contact with Li precipitates. In order to effectively prevent Li ions from reaching the negative electrode current collector 11 via the negative electrode layer 12, the Li ion conductivity of the alloying prevention layer 13 is preferably 10 ⁻⁸ S / m or less, More preferably, it is substantially zero. In addition, the alloying prevention layer 13 has an electron conductivity of 10 ⁶ S / m or more, thereby sufficiently allowing electron conduction between the negative electrode layer 12 and the negative electrode current collector 11, and charging the lithium ion battery. Ensuring sufficient current collection of the electrode body for discharge. Further, in order to prevent the sulfide contained in the negative electrode layer 12 from reacting with the solid electrolyte, the alloying prevention layer 13 is made of a material that does not react with sulfide.

  Examples of the constituent material of the alloying prevention layer 13 include a material mainly composed of a carbon material. Examples of the carbon material include graphite, carbon black such as acetylene black (AB) and ketjen black (KB), carbon nanotube (CNT), and the like. Among the carbon materials, it is particularly preferable to use graphite. The alloying prevention layer 13 is mainly composed of one or more selected from the above-described carbon materials, and may additionally contain a conductive material. Examples of the conductive material include one selected from Ni, Fe, Cr, and alloys thereof (for example, stainless steel). Even if the alloying prevention layer 13 includes a conductive material conventionally used as a negative electrode current collector, if the amount thereof is relatively small, the amount of expensive material used for the entire negative electrode body can be reduced. When the alloying prevention layer 13 is made of a mixed material of a carbon material and a conductive material, a preferable range of the mixing ratio is 70:30 to 95: 5.

  The constituent material of the alloying prevention layer 13 and the constituent material of the negative electrode active material particles contained in the negative electrode layer 12 are preferably the same. Since both are the same, the adhesion between the anti-alloying layer 13 and the negative electrode layer 12 is improved, and cracks and the like are less likely to occur at the bonding interface between the anti-alloying layer 13 and the negative electrode layer 12, and the high resistance layer Formation can be further prevented.

  The thickness of the alloying prevention layer 13 is 10 μm or more, so that a sufficient space between the negative electrode current collector 11 and the negative electrode layer 12 can be secured, and Li and Al can react and be alloyed. This can prevent the formation of the high resistance layer on the negative electrode current collector 13. On the other hand, when the thickness is 50 μm or less, enlargement of the negative electrode body 1 can be prevented. For example, when the alloying prevention layer 13 is formed of graphite, the thickness of the alloying prevention layer 13 is preferably 10 to 30 μm.

  If the constituent material is powder, the alloying prevention layer 13 may be produced by pressing the powder, or may be produced by a vapor phase method such as a vacuum deposition method or a laser ablation method.

  Examples of a method for forming the negative electrode body 1 include a method in which the constituent members of the negative electrode body 1 (the negative electrode layer 12, the alloying prevention layer 13, and the negative electrode current collector 11) are pressure-formed at a time. When the constituent material of the anti-alloying layer 13 is in powder form, first, the powder that becomes the constituent material of the negative electrode layer 12 is filled in the mold, and then the powder that becomes the constituent material of the anti-alloying layer 13 is filled in layers. To do. Furthermore, a negative electrode current collector 11 made of Al or an Al alloy is disposed thereon. By forming the negative electrode layer 12, the alloying prevention layer 13, and the negative electrode current collector 11 at a time, the adhesion between the members 12, 13, and 11 is improved. In addition, the negative electrode layer 12 and the alloying prevention layer 13 may be pressure-molded, and the negative electrode current collector 11 may be bonded onto the alloying prevention layer 13. In addition, the negative electrode layer 12 and the alloying prevention layer 13 may be separately pressure-molded. In any case, the pressure is preferably 150 to 550 MPa.

[Positive electrode body]
The positive electrode body 2 includes a positive electrode current collector 21 and a positive electrode layer 22.

(Positive electrode current collector)
The positive electrode current collector 21 is a conductive material, and it is preferable to use a material made of Al or an Al alloy from the viewpoint of easy handling and low cost. The positive electrode current collector 21 may be composed of only a conductive material, or may be composed of a conductive material film formed on an insulating substrate. In the latter case, the conductive material functions as a current collector.

(Positive electrode layer)
The positive electrode layer 22 is a layer obtained by pressure-molding a powder containing positive electrode active material particles that are the main component of the battery reaction. As the positive electrode active material, a material having a layered rock salt type crystal structure, for example, Liα _X β _(1-X) O ₂ (α is one selected from Co, Ni, Mn, β is Fe, Al, Ti , Cr, Zn, Mo and Bi, and X is 0.5 or more). Specific examples thereof include LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiCo _0.5 Fe _0.5 O ₂ , LiCo _0.5 Al _0.5 O _{2 and the} like. In addition, a system such as LiNi _0.80 Co _0.15 Al _0.05 O ₂ is also applicable. In addition, as the positive electrode active material, a substance having a spinel crystal structure (for example, LiMn ₂ O ₄ ) or a substance having an olivine crystal structure (for example, Li _X FePO ₄ (0 <X <1)) is used. It can also be used.

The positive electrode layer 22 may contain solid electrolyte particles that mediate Li ion conduction in the positive electrode layer 22 and improve Li ion conductivity. As solid electrolyte particles, a sulfide system such as Li ₂ SP ₂ S ₅ can be suitably used. In addition, you may contain a conductive support agent and a binder (binder) as needed.

  The conditions for pressure molding of the positive electrode layer 22 can be appropriately selected. For example, the pressurizing pressure is preferably 150 to 550 MPa.

[Solid electrolyte layer]
The solid electrolyte layer (SE layer) 3 is composed of a solid electrolyte, and is preferably composed of a sulfide-based solid electrolyte having high Li ion conductivity. Examples of sulfide-based solid electrolytes include Li ₂ SP ₂ S ₅ system, Li ₂ S-SiS ₂ system, Li ₂ SB ₂ S ₃ system, and P ₂ O ₅ and Li ₃ PO ₄ are added. Also good. The same material as that of the sulfide solid electrolyte particles, which are constituent materials of the negative electrode layer 12, may be used. In addition, you may comprise with oxide type solid electrolytes, such as LiPON.

  As shown in FIG. 2, the SE layer 3 includes a negative electrode side solid electrolyte layer (NSE layer) 3a formed on the negative electrode layer 12 side of the negative electrode body 1, and a positive electrode side solid electrolyte formed on the positive electrode layer 22 side of the positive electrode body 2. It is formed by pressure welding the layer (PSE layer) 3b. The NSE layer 3a and the PSE layer 3b are composed of the same solid electrolyte.

[Others]
Depending on the material of the positive electrode layer 22 and the SE layer 3 (PSE layer 3b), an intermediate layer (not shown) may be provided between the positive electrode layer 22 and the SE layer 3 (PSE layer 3b). The intermediate layer is necessary when a solid sulfide is used for the SE layer 3, and is a layer that suppresses an increase in resistance between the positive electrode layer 22 and the SE layer 3. The sulfide solid electrolyte contained in the SE layer and the positive electrode active material of oxide contained in the positive electrode layer 22 may react to form a high resistance layer. By providing the intermediate layer, the formation of the high resistance layer can be suppressed, and the decrease in the discharge capacity of the lithium ion battery 100 associated with charge / discharge can be suppressed. As the material used for the intermediate layer, an amorphous Li ion conductive oxide such as LiNbO ₃ or LiTaO ₃ can be used. In particular, LiNbO ₃ can effectively suppress an increase in resistance in the vicinity of the interface between the positive electrode layer 22 and the SE layer 3.

  The lithium ion battery of this invention was produced and the battery performance was evaluated.

[Lithium ion battery of Example]
Graphite powder (volume distribution center particle size D50 = 10 μm), Li ₂ SP ₂ S ₅ solid electrolyte powder (D50 = 2.5 μm, ionic conductivity = 3 × 10 ⁻⁴ S / cm) and PTFE binder, A negative electrode mixture was prepared by mixing with a ball mill at a volume ratio of 48.5: 48.5: 3 at 50 rpm for 4 hours. This negative electrode mixture is filled in a mold, and graphite (D50 = 10 μm, electron conductivity = 10 ⁶ S / m, ion conductivity = 0 S / m) is filled in a layer thereon, and Al is further formed thereon. A foil (thickness 20 μm) was placed. This was press-molded at a pressure of 360 MPa while the mold temperature was 200 ° C. By doing so, an alloying prevention layer (graphite compact) is formed on the negative electrode current collector (Al foil), and the negative electrode layer (graphite + Li ₂ SP ₂ S ₅ solid electrolyte is formed on the alloying prevention layer. A negative electrode body is formed on which is formed. The thickness of the negative electrode layer in this negative electrode body was 60 μm, and the thickness of the alloying prevention layer was 30 μm. The graphite constituting the alloying prevention layer and the graphite contained in the negative electrode layer are materials having the same characteristics.

Also, LiCoO ₂ powder (D50 = 10 μm), Li ₂ SP ₂ S ₅ solid electrolyte powder (D50 = 2.5 μm, ionic conductivity = 3 × 10 ⁻⁴ S / cm) and acetylene black (D50 = 3 μm) And PTFE binder were mixed by a ball mill at a volume ratio of 48: 48: 3: 1 at 50 rpm for 4 hours to produce a positive electrode mixture. This positive electrode mixture was filled in a mold, and a positive electrode current collector made of Al foil (thickness 20 μm) was disposed thereon. This was press-molded at a pressure of 360 MPa while the mold temperature was 200 ° C. By doing so, a positive electrode body in which a positive electrode layer (formed body of LiCoO ₂ + Li ₂ SP ₂ S ₅ based solid electrolyte) is formed on the positive electrode current collector (Al foil) is formed. The thickness of the positive electrode layer in this positive electrode body was 60 μm.

Next, on the negative electrode layer of the negative electrode body and on the positive electrode layer of the positive electrode body, respectively, a Li ₂ S-P ₂ S ₅ solid electrolyte was formed by vapor deposition, and the negative electrode side solid electrolyte layer ( And a positive electrode side solid electrolyte layer (thickness 5 μm).

  Then, the two electrode bodies were laminated so that the solid electrolyte layers formed on the negative electrode body and the positive electrode body were opposed to each other (see FIG. 2), pressurized in the laminating direction at a pressure of 10 MPa, and at a temperature of 190 ° C. for 120 minutes. By heating, the solid electrolyte layers were fused together to join both electrode bodies (see FIG. 1), thereby producing a lithium ion battery.

  The lithium ion battery produced as described above was incorporated into a charge / discharge test cell, and this was designated as Sample No. 1-1.

[Lithium ion battery of comparative example]
A lithium ion battery was fabricated in the same manner as Sample No. 1-1 except that in the negative electrode body, an alloying prevention layer was not formed. That is, this negative electrode body is a negative electrode body in which a negative electrode layer (graphite + Li ₂ SP ₂ S ₅ based solid electrolyte compact) is formed on a negative electrode current collector (Al). This lithium ion battery was incorporated into a charge / discharge test cell, and this was designated as Sample No. 1-2.

  A lithium ion battery was fabricated in the same manner as Sample No. 1-2 except that the negative electrode body was fabricated by changing the constituent material of the negative electrode layer. This negative electrode body was formed by depositing a metal Li foil (20 μm) on the negative electrode current collector (Al) by vapor deposition. That is, this negative electrode body is a negative electrode body in which a negative electrode layer (metal Li) is formed on a negative electrode current collector (Al). This lithium ion battery was incorporated into a charge / discharge test cell, and this was designated as Sample No. 1-3.

[Battery evaluation]
For sample No.1-1 to 1-3 lithium-ion batteries, a charge / discharge cycle test with one cycle of charge / discharge was performed at a constant current of 0.05 mA / cm ² with a cutoff voltage of 3.0-4.2 V The charge / discharge cycle characteristics were examined.

  As a result, it was confirmed that the lithium ion battery of Sample No. 1-1 operated stably even after 100 cycles. On the other hand, the battery of sample No. 1-2 was 15 cycles, and the battery of sample No. 1-3 was 12 cycles.

  When the lithium ion battery of each sample was disassembled after the test was completed and the negative electrode current collector was confirmed, no cracks were found in the negative electrode current collector of sample No. 1-1. It was visually observed that the negative electrode current collector of -3 had cracks.

  From the above results, when a material containing Al is used for the negative electrode current collector in the negative electrode body, an anti-alloying layer is provided between the negative electrode current collector and the negative electrode layer, so that charging / discharging of the lithium ion battery can be performed. It can be seen that Li can be prevented from being deposited on the negative electrode current collector by repetition, and Li and Al can be prevented from reacting and alloying. It can be seen that the charge-discharge cycle characteristics can be improved by preventing the alloying of Li and Al.

  The above-described embodiments can be appropriately changed without departing from the gist of the present invention, and the scope of the present invention is not limited to the above-described configuration.

  The negative electrode body of the present invention can be suitably used for a lithium ion battery as a power source for various electric devices.

100 lithium ion battery
1 Negative electrode body
11 Negative electrode current collector 12 Negative electrode layer 13 Anti-alloying layer
2 Positive electrode body
21 Positive electrode current collector 22 Positive electrode layer
3 Solid electrolyte layer (SE layer)
3a Negative electrode side solid electrolyte layer (NSE layer) 3b Positive electrode side solid electrolyte layer (PSE layer)

Claims (5)

A negative electrode body used in a lithium ion battery,
A negative electrode current collector made of Al or Al alloy;
A negative electrode layer comprising a mixed powder of negative electrode active material particles and sulfide solid electrolyte particles;
Intervening between the negative electrode current collector and the negative electrode layer, and comprising an alloying prevention layer for preventing alloying of Li and Al,
The alloying prevention layer is made of a material having an electron conductivity of 10 ⁶ S / m or more and does not react with sulfide.   2. The negative electrode body according to claim 1, wherein the alloying prevention layer is made of a material mainly composed of a carbon material.   3. The negative electrode body according to claim 2, wherein the negative electrode active material particles are made of the same material as the carbon material constituting the alloying prevention layer.   4. The negative electrode body according to claim 1, wherein a thickness of the alloying prevention layer is 10 to 50 μm. A lithium ion battery comprising a positive electrode body, a negative electrode body, and a solid electrolyte layer disposed between both electrode bodies,
5. The lithium ion battery according to claim 1, wherein the negative electrode body is the negative electrode body according to any one of claims 1 to 4.

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