JP6894201B2 - Non-aqueous electrolyte secondary battery - Google Patents

Description

The present invention relates to a non-aqueous electrolyte secondary battery.

Non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries (lithium secondary batteries) are lighter and have higher energy density than existing batteries. Therefore, in recent years, so-called portable power sources such as personal computers and mobile terminals and vehicle drive It is used as a power source. In particular, lithium-ion secondary batteries, which are lightweight and have high energy density, will become more and more popular as high-output power sources for driving vehicles such as electric vehicles (EV), hybrid vehicles (HV), and plug-in hybrid vehicles (PHV). It is expected to continue.

In a typical configuration of a non-aqueous electrolyte secondary battery, the positive electrode comprises a positive electrode active material layer containing a positive electrode active material. A lithium composite metal oxide containing lithium and other metals, a lithium transition metal phosphoric acid compound, and the like are typically used as the positive electrode active material, and typical examples of the other metals include There are manganese (Mn), nickel (Ni), cobalt (Co), iron (Fe) and the like.

In a non-aqueous electrolyte secondary battery, the above-mentioned other metals are eluted from the positive electrode active material due to the generation of acid (eg, hydrofluoric acid) due to the decomposition of the non-aqueous electrolyte, especially during repeated charging and discharging at a high temperature. However, it is known that this eluted metal can adversely affect the battery characteristics. Therefore, Patent Document 1 describes a technique in which zeolite is arranged in the positive electrode active material layer to trap Fe or Mn eluted from the positive electrode active material in order to suppress capacity deterioration of the lithium ion secondary battery. Proposed.

Patent No. 5309927

As a result of diligent studies by the present inventor, the technique described in Patent Document 1 for trapping an eluted metal using ordinary zeolite has improved the metal lithium precipitation resistance when a non-aqueous electrolyte secondary battery is repeatedly charged and discharged. It turned out that there was room.

Therefore, an object of the present invention is to provide a non-aqueous electrolyte secondary battery having high resistance to metallic lithium precipitation during repeated charging and discharging.

The non-aqueous electrolyte secondary battery disclosed herein includes a positive electrode having a positive electrode active material layer containing a positive electrode active material, a negative electrode, an electrode body having a separator interposed between the positive and negative electrodes, and a non-aqueous electrolyte. Including. In the non-aqueous electrolyte secondary battery, Ag-containing zeolite is arranged in at least one of the positive electrode active material layer, the positive electrode active material layer surface, the separator surface, and the separator.
According to such a configuration, not only the metal eluted from the positive electrode active material can be trapped by the zeolite, but also the Ag ion released from the zeolite can be precipitated and supported on the negative electrode, so that the resistance of the negative electrode can be supported. Can be reduced. As a result, the resistance to metal lithium precipitation during repeated charging and discharging can be enhanced. Therefore, according to such a configuration, it is possible to provide a non-aqueous electrolyte secondary battery having high resistance to metallic lithium precipitation during repeated charging and discharging.

It is sectional drawing which shows typically the internal structure of the lithium ion secondary battery which concerns on one Embodiment of this invention. It is a schematic diagram which shows the structure of the winding electrode body of the lithium ion secondary battery which concerns on one Embodiment of this invention. It is a schematic diagram which shows a part of the laminated structure of the wound electrode body of the lithium ion secondary battery which concerns on one Embodiment of this invention.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. It should be noted that matters other than those specifically mentioned in the present specification and necessary for carrying out the present invention (for example, general configurations and manufacturing processes of non-aqueous electrolyte secondary batteries that do not characterize the present invention). Can be grasped as a design matter of a person skilled in the art based on the prior art in the field. The present invention can be carried out based on the contents disclosed in the present specification and common general technical knowledge in the art. Further, in the following drawings, members / parts having the same action are described with the same reference numerals. Further, the dimensional relations (length, width, thickness, etc.) in each drawing do not reflect the actual dimensional relations.

In the present specification, the "secondary battery" generally refers to a power storage device that can be repeatedly charged and discharged, and is a term that includes a so-called storage battery such as a lithium ion secondary battery and a power storage element such as an electric double layer capacitor.
Hereinafter, the present invention will be described in detail by taking a flat-angle type lithium ion secondary battery as an example, but the present invention is not intended to be limited to those described in such embodiments.

The lithium ion secondary battery 100 shown in FIG. 1 is constructed by housing a flat wound electrode body 20 and a non-aqueous electrolyte (not shown) in a flat square battery case (that is, an outer container) 30. It is a closed type lithium ion secondary battery 100. The battery case 30 is provided with a positive electrode terminal 42 and a negative electrode terminal 44 for external connection, and a thin-walled safety valve 36 set to release the internal pressure when the internal pressure of the battery case 30 rises above a predetermined level. There is. Further, the battery case 30 is provided with an injection port (not shown) for injecting a non-aqueous electrolyte. The positive electrode terminal 42 is electrically connected to the positive electrode current collector plate 42a. The negative electrode terminal 44 is electrically connected to the negative electrode current collector plate 44a. As the material of the battery case 30, for example, a lightweight metal material having good thermal conductivity such as aluminum is used.

In the wound electrode body 20, as shown in FIGS. 1 and 2, a positive electrode active material layer 54 is formed along the longitudinal direction on one side or both sides (here, both sides) of the elongated positive electrode current collector 52. The positive electrode sheet 50 and the negative electrode sheet 60 in which the negative electrode active material layer 64 is formed along the longitudinal direction on one side or both sides (here, both sides) of the long negative electrode current collector 62 are formed in two long shapes. It has a form of being overlapped with each other via a separator sheet 70 and wound in the longitudinal direction. The positive electrode active material layer non-formed portion 52a (that is, the positive electrode) formed so as to protrude outward from both ends of the winding electrode body 20 in the winding axis direction (referring to the sheet width direction orthogonal to the longitudinal direction). A portion where the positive electrode current collector 52 is exposed without forming the active material layer 54) and a portion 62a where the negative electrode active material layer is not formed (that is, a portion where the negative electrode current collector 62 is exposed without forming the negative electrode active material layer 64). ) Are joined to a positive electrode current collector plate 42a and a negative electrode current collector plate 44a, respectively.

As the positive electrode sheet 50 and the negative electrode sheet 60, the same ones used in the conventional lithium ion secondary battery can be used without particular limitation. A typical aspect is shown below.

Examples of the positive electrode current collector 52 constituting the positive electrode sheet 50 include aluminum foil and the like. Examples of the positive electrode active material contained in the positive electrode active material layer 54 include lithium transition metal oxides (eg, LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNiO ₂ , LiCoO ₂ , LiFeO ₂ , LiMn ₂ O). ₄ , LiNi _0.5 Mn _1.5 O _4, etc.), lithium transition metal phosphate compounds (eg, LiFePO _4, etc.) and the like. The positive electrode active material is preferably a lithium transition metal oxide containing at least one transition metal selected from the group consisting of Ni, Mn, Co, and Fe because the Ag-containing zeolite elutes ions that are easily trapped. The positive electrode active material layer 54 may contain components other than the active material, such as a conductive material and a binder. As the conductive material, for example, carbon black such as acetylene black (AB) or other carbon material (eg, graphite or the like) can be preferably used. As the binder, for example, polyvinylidene fluoride (PVDF) or the like can be used.

Examples of the negative electrode current collector 62 constituting the negative electrode sheet 60 include copper foil and the like. As the negative electrode active material contained in the negative electrode active material layer 64, a carbon material such as graphite, hard carbon, or soft carbon can be used. The negative electrode active material layer 64 may contain components other than the active material, such as a binder and a thickener. As the binder, for example, styrene butadiene rubber (SBR) or the like can be used. As the thickener, for example, carboxymethyl cellulose (CMC) or the like can be used.

Examples of the separator 70 include a porous sheet (film) made of a resin such as polyethylene (PE), polypropylene (PP), polyester, cellulose, and polyamide. Such a porous sheet may have a single-layer structure or a laminated structure of two or more layers (for example, a three-layer structure in which PP layers are laminated on both sides of a PE layer).

Further, as the separator 70, as shown in FIG. 3, a separator having a heat-resistant layer (HRL) 72 and a base material layer 74 may be used. The heat-resistant layer 72 contains an inorganic filler such as alumina, boehmite, and magnesia, and if necessary, a binder (eg, acrylic polymer, styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), etc.), a thickener (thickening agent) ( For example, carboxymethyl cellulose (CMC), methyl cellulose, etc.) may be included. The above-mentioned porous sheet can be used for the base material layer 74.

In the present embodiment, the Ag-containing zeolite is arranged in at least one of the positive electrode active material layer 54, the positive electrode active material layer 54 surface, the separator 70 surface, and the separator 70. Hereinafter, this will be specifically described with reference to embodiments.

In one aspect of the present embodiment, Ag-containing zeolite is uniformly dispersed and present in the positive electrode active material layer 54. In this way, the Ag-containing zeolite is arranged in the positive electrode active material layer 54. Further, since the Ag-containing zeolite is uniformly arranged in the positive electrode active material layer 54, the Ag-containing zeolite is also arranged on the surface of the positive electrode active material layer 54 at a low concentration. In the positive electrode sheet 50 in which the Ag-containing zeolite is uniformly dispersed in the positive electrode active material layer 54, for example, the positive electrode active material, the Ag-containing zeolite, and if necessary, a conductive material, a binder, or the like are used as N-. A positive electrode paste (including positive electrode slurry and positive electrode ink) obtained by uniformly mixing in a solvent such as methylpyrrolidone (NMP) was prepared, and the positive electrode paste was applied on one or both sides of the positive electrode current collector 52. After that, it can be produced by drying.

In another aspect of this embodiment, an Ag-containing zeolite layer is provided on the surface of the positive electrode active material layer 54. In this way, Ag-containing zeolite is arranged at a high concentration on the surface of the positive electrode active material layer 54. In the positive electrode sheet 50 in which the Ag-containing zeolite layer is provided on the surface of the positive electrode active material layer 54, for example, a coating liquid containing Ag-containing zeolite and, if necessary, a binder or the like is applied onto the positive electrode active material layer 54. After that, it can be produced by drying.

In another aspect of the present embodiment, the separator 70 has a heat-resistant layer 72 and a base material layer 74, and Ag-containing zeolite is uniformly dispersed in the heat-resistant layer 72. In this way, Ag-containing zeolite is arranged on the surface of the separator 70. The heat-resistant layer 72 may be provided on the surface of the base material layer 74 facing the positive electrode 50, or may be provided on the surface of the base material layer 74 facing the negative electrode 60. The separator 70 in which the Ag-containing zeolite is uniformly dispersed in the heat-resistant layer 72 is, for example, an inorganic filler, an Ag-containing zeolite, and a binder, if necessary, on a porous sheet to be the base material layer 74. It can be produced by applying a coating liquid containing a thickener or the like and then drying it.

In yet another aspect of this embodiment, the separator 70 is provided with an Ag-containing zeolite layer between the heat-resistant layer 72 and the base material layer 74. In this way, the Ag-containing zeolite is arranged in the separator 70. The separator 70 in which the Ag-containing zeolite layer is provided between the heat-resistant layer 72 and the base material layer 74 is provided with, for example, Ag-containing zeolite and, if necessary, a binder or the like on a porous sheet to be the base material layer 74. After applying the coating liquid containing the above, it is dried to prepare an Ag-containing zeolite layer, and the heat-resistant layer 72 is provided on the Ag-containing zeolite layer according to a conventional method. Alternatively, Ag-containing zeolite may be arranged in the separator 70 containing only the porous sheet.

Although the four aspects of the present embodiment have been described above, in the present embodiment, two or more of the above four aspects can be combined.

In this embodiment, Ag-containing zeolite is used. That is, zeolite is based on a skeleton made of silicon dioxide, and the entire crystal lattice is negatively charged by substituting a part of silicon with aluminum, and monovalent cations are used to balance the charges. Contains ions. A normal zeolite contains a Na ion as a monovalent cation, but the zeolite used in this embodiment contains an Ag ion as a monovalent cation.

The metal eluted from the positive electrode active material is deposited on the negative electrode and closes the active surface of the negative electrode. Since metallic lithium is likely to precipitate in the portion where the active surface of the negative electrode is closed, the metallic lithium precipitation resistance when the non-aqueous electrolyte secondary battery is repeatedly charged and discharged is lowered. Even when ordinary zeolite is used as in the past, by trapping the eluted metal from the positive electrode active material with zeolite, the deposition of the eluted metal on the negative electrode can be suppressed, so that the metal lithium precipitation resistance is improved. To do.

However, while ordinary zeolite contains Na ion, the zeolite used in this embodiment contains Ag ion. Therefore, when the zeolite traps the eluted metal from the positive electrode active material, Ag ions are released from the zeolite. The Ag ions released from the zeolite are precipitated and supported on the negative electrode 60 (particularly the negative electrode active material layer 64). Since Ag easily permeates Li and has good Li ion conductivity, the resistance of the negative electrode 60 can be reduced. For this reason, when Ag-containing zeolite is used as in the present embodiment, the metal lithium precipitation resistance during repeated charging and discharging can be significantly increased as compared with the case where normal Na-containing zeolite is used. it can. Further, as a method of forming an Ag film on the negative electrode 60 (particularly, the negative electrode active material layer 64) in order to reduce the resistance of the negative electrode 60, it is also excellent in terms of simplicity.

The pore size of the Ag-containing zeolite may be appropriately determined according to the type of metal ion to be trapped (that is, the type of metal contained in the positive electrode active material). That is, as the pore diameter of the Ag-containing zeolite, a pore diameter capable of trapping the metal ion to be trapped may be appropriately adopted, and in particular, a pore diameter slightly larger than the metal ion to be trapped may be appropriately adopted.
The Ag-containing zeolite can be obtained by exchanging the Na ion of the Na-containing zeolite with the Ag ion, and can also be obtained as a commercially available product.

As the non-aqueous electrolyte, the same one as that of the conventional lithium ion secondary battery can be used, and typically, an organic solvent (non-aqueous solvent) containing a supporting salt can be used. As the non-aqueous solvent, various organic solvents such as carbonates, ethers, esters, nitriles, sulfones, and lactones used in the electrolytic solution of a general lithium ion secondary battery are used without particular limitation. Can be done. Specific examples include ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), monofluoroethylene carbonate (MFEC), difluoroethylene carbonate (DFEC), Examples thereof include monofluoromethyldifluoromethyl carbonate (F-DMC) and trifluorodimethyl carbonate (TFDMC). As such a non-aqueous solvent, one type can be used alone, or two or more types can be used in combination as appropriate. As the supporting salt, for example, a lithium salt (preferably LiPF _{6 ) such as LiPF 6} , LiBF ₄ , and LiClO ₄ can be preferably used. The concentration of the supporting salt is preferably 0.7 mol / L or more and 1.3 mol / L or less.

The non-aqueous electrolyte may be a gas generator such as biphenyl (BP) or cyclohexylbenzene (CHB); an oxalate complex compound containing a boron atom and / or a phosphorus atom, as long as the effects of the present invention are not significantly impaired. It may contain various additives such as a film forming agent such as vinylene carbonate (VC); a dispersant; and a thickener.

The lithium ion secondary battery 100 configured as described above can be used for various purposes. Suitable applications include drive power supplies mounted on vehicles such as electric vehicles (EVs), hybrid vehicles (HVs), and plug-in hybrid vehicles (PHVs). The lithium ion secondary battery 100 may also be used in the form of an assembled battery, which typically consists of a plurality of batteries connected in series and / or in parallel.

As an example, a square lithium ion secondary battery 100 including a flat wound electrode body 20 has been described. However, the lithium ion secondary battery can also be configured as a lithium ion secondary battery including a laminated electrode body. The lithium ion secondary battery can also be configured as a cylindrical lithium ion secondary battery. The technology disclosed herein is also applicable to non-aqueous electrolyte secondary batteries other than lithium ion secondary batteries.

Hereinafter, examples relating to the present invention will be described, but the present invention is not intended to be limited to those shown in such examples.

<Preparation of zeolite>
(Na-containing zeolite)
A Na-containing zeolite having a pore diameter of 4 angstroms was pulverized so as to have an average particle diameter of 1 μm.
(Li-containing zeolite)
90% of Na ions of Na-containing zeolite that had been pulverized so as to have an average particle size of 1 μm were replaced with Li ions by an ion exchange method.
(Ag-containing zeolite)
90% of Na ions of Na-containing zeolite that had been pulverized so as to have an average particle size of 1 μm were replaced with Ag ions by an ion exchange method.

<Battery No. Preparation of 1>
_{LiNi 1/3} Co _1/3 Mn _1/3 O ₂ (LNCM) as the positive electrode active material powder, AB as the conductive material, and PVDF as the binder are used as LNCM: AB: PVDF = 90: 8: 2. A paste for forming a positive electrode active material layer was prepared by mixing with N-methylpyrrolidone (NMP) in a mass ratio of. This paste was applied in strips on both sides of an aluminum foil (positive electrode current collector) (application amount: 6 mg / cm ² per side) and dried to prepare a positive electrode.
Further, graphite (C) as a negative electrode active material, CMC as a thickener, and SBR as a binder are mixed with ion-exchanged water at a mass ratio of C: CMC: SBR = 98: 1: 1. , A paste for forming a negative electrode active material layer was prepared. This paste was applied to both sides of a copper foil (negative electrode current collector) in a strip shape (application amount: 3 mg / cm ² per side) and dried to prepare a negative electrode.
Boehmite, an acrylic polymer as a binder, and CMC as a thickener are mixed with ion-exchanged water at a mass ratio of boehmite: acrylic polymer: CMC = 95: 2.5: 2.5 to withstand heat resistance. A coating liquid for layer formation was prepared. This coating liquid is applied to one side of a sheet-shaped separator base material (a porous sheet having a three-layer structure of PP / PE / PP with an average thickness of 20 μm) (application amount: 0.75 mg / cm ² ) and dried. To prepare a separator.
The prepared positive electrode, negative electrode, and separator were laminated so that the separator was interposed between the positive and negative electrodes, and wound to obtain an electrode body. At this time, the heat-resistant layer of the separator was made to face the negative electrode.
The prepared electrode body was housed in a battery case. Subsequently, a non-aqueous electrolyte was injected through the opening of the battery case, and the opening was hermetically sealed to prepare a lithium ion secondary battery assembly. The non-aqueous electrolyte contains a mixed solvent containing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of EC: EMC: DMC = 3: 3: 4, and a supporting salt. LiPF ₆ was dissolved at a concentration of 1.1 mol / L. After the electrode body was sufficiently impregnated with a non-aqueous electrolyte, the lithium ion secondary battery assembly was initially charged and aged at 60 ° C. at 60 ° C. with 100% SOC (state of charge) for 24 hours. A lithium ion secondary battery of 1 was obtained.

<Battery No. Preparation of 2>
_{LiNi 1/3} Co _1/3 Mn _1/3 O ₂ (LNCM) as a positive electrode active material powder, AB as a conductive material, PVDF as a binder, and Na-containing zeolite are used as LNCM: AB: PVDF: A paste for forming a positive electrode active material layer was prepared by mixing with N-methylpyrrolidone (NMP) at a mass ratio of Na-containing zeolite = 90: 8: 2: 5. This paste was applied in strips on both sides of an aluminum foil (positive electrode current collector) (application amount: 6.3 mg / cm ² per side) and dried to prepare a positive electrode.
Except for using this positive electrode, the battery No. Battery No. 1 was prepared in the same manner as in No. 1. A lithium ion secondary battery of 2 was obtained.

<Battery No. Preparation of 3>
The mass of boehmite, Na-containing zeolite, acrylic polymer as a binder, and CMC as a thickener, boehmite: Na-containing zeolite: acrylic polymer: CMC = 55: 40: 2.5: 2.5. A coating liquid for forming a heat-resistant layer was prepared by mixing with ion-exchanged water in a ratio. This coating liquid is applied to one side of a sheet-shaped separator base material (a porous sheet having a three-layer structure of PP / PE / PP with an average thickness of 20 μm) (application amount: 0.75 mg / cm ² ) and dried. To prepare a separator.
Except for using this separator, the battery No. Battery No. 1 was prepared in the same manner as in No. 1. A lithium ion secondary battery of 3 was obtained.

<Battery No. Preparation of 4>
The mass of boehmite, Na-containing zeolite, acrylic polymer as a binder, and CMC as a thickener, boehmite: Na-containing zeolite: acrylic polymer: CMC = 55: 40: 2.5: 2.5. A coating liquid for forming a heat-resistant layer was prepared by mixing with ion-exchanged water in a ratio. This coating liquid is applied to one side of a sheet-shaped separator base material (a porous sheet having a three-layer structure of PP / PE / PP with an average thickness of 20 μm) (application amount: 0.75 mg / cm ² ) and dried. To prepare a separator.
Using this separator, the battery No. 1 was used, except that the heat-resistant layer of the separator was made to face the positive electrode when the electrode body was manufactured. Battery No. 1 was prepared in the same manner as in No. 1. A lithium ion secondary battery of 4 was obtained.

<Battery No. Preparation of 5>
The mass of graphite (C) as a negative electrode active material, CMC as a thickener, SBR as a binder, and Na-containing zeolite as C: CMC: SBR: Na-containing zeolite = 98: 1: 1: 9. A paste for forming a negative electrode active material layer was prepared by mixing with ion-exchanged water in a ratio. This paste was applied to both sides of a copper foil (negative electrode current collector) in a strip shape (application amount: 3.3 mg / cm ² per side) and dried to prepare a negative electrode.
Except for using this negative electrode, the battery No. Battery No. 1 was prepared in the same manner as in No. 1. A lithium ion secondary battery of 5 was obtained.

<Battery No. Preparation of 6>
_{LiNi 1/3} Co _1/3 Mn _1/3 O ₂ (LNCM) as a positive electrode active material powder, AB as a conductive material, PVDF as a binder, and Li-containing zeolite are used as LNCM: AB: PVDF: A paste for forming a positive electrode active material layer was prepared by mixing with N-methylpyrrolidone (NMP) at a mass ratio of Li-containing zeolite = 90: 8: 2: 5. This paste was applied in strips on both sides of an aluminum foil (positive electrode current collector) (application amount: 6.3 mg / cm ² per side) and dried to prepare a positive electrode.
Except for using this positive electrode, the battery No. Battery No. 1 was prepared in the same manner as in No. 1. A lithium ion secondary battery of 6 was obtained.

<Battery No. Preparation of 7>
The mass of boehmite, Li-containing zeolite, acrylic polymer as a binder, and CMC as a thickener, boehmite: Li-containing zeolite: acrylic polymer: CMC = 55: 40: 2.5: 2.5. A coating liquid for forming a heat-resistant layer was prepared by mixing with ion-exchanged water in a ratio. This coating liquid is applied to one side of a sheet-shaped separator base material (a porous sheet having a three-layer structure of PP / PE / PP with an average thickness of 20 μm) (application amount: 0.75 mg / cm ² ) and dried. To prepare a separator.
Except for using this separator, the battery No. Battery No. 1 was prepared in the same manner as in No. 1. A lithium ion secondary battery of 7 was obtained.

<Battery No. Preparation of 8>
The mass of boehmite, Li-containing zeolite, acrylic polymer as a binder, and CMC as a thickener, boehmite: Li-containing zeolite: acrylic polymer: CMC = 55: 40: 2.5: 2.5. A coating liquid for forming a heat-resistant layer was prepared by mixing with ion-exchanged water in a ratio. This coating liquid is applied to one side of a sheet-shaped separator base material (a porous sheet having a three-layer structure of PP / PE / PP with an average thickness of 20 μm) (application amount: 0.75 mg / cm ² ) and dried. To prepare a separator.
Using this separator, the battery No. 1 was used except that the heat-resistant layer of the separator was made to face the positive electrode when the electrode body was manufactured. Battery No. 1 was prepared in the same manner as in No. 1. A lithium ion secondary battery of 8 was obtained.

<Battery No. Preparation of 9>
Graphite (C) as a negative electrode active material, CMC as a thickener, SBR as a binder, and Li-containing zeolite have a mass ratio of C: CMC: SBR: Li-containing zeolite = 98: 1: 1: 9. A paste for forming a negative electrode active material layer was prepared by mixing with ion-exchanged water in a ratio. This paste was applied to both sides of a copper foil (negative electrode current collector) in a strip shape (application amount: 3.3 mg / cm ² per side) and dried to prepare a negative electrode.
Except for using this negative electrode, the battery No. Battery No. 1 was prepared in the same manner as in No. 1. A lithium ion secondary battery of 9 was obtained.

<Battery No. Preparation of 10>
_{LiNi 1/3} Co _1/3 Mn _1/3 O ₂ (LNCM) as a positive electrode active material powder, AB as a conductive material, PVDF as a binder, and Ag-containing zeolite are used as LNCM: AB: PVDF: Ag-containing zeolite = 90: 8: 2: 5 was mixed with N-methylpyrrolidone (NMP) at a mass ratio to prepare a paste for forming a positive electrode active material layer. This paste was applied in strips on both sides of an aluminum foil (positive electrode current collector) (application amount: 6.3 mg / cm ² per side) and dried to prepare a positive electrode.
Except for using this positive electrode, the battery No. Battery No. 1 was prepared in the same manner as in No. 1. Ten lithium ion secondary batteries were obtained.

<Battery No. Preparation of 11>
The mass of boehmite, Ag-containing zeolite, acrylic polymer as a binder, and CMC as a thickener, boehmite: Ag-containing zeolite: acrylic polymer: CMC = 55: 40: 2.5: 2.5. A coating liquid for forming a heat-resistant layer was prepared by mixing with ion-exchanged water in a ratio. This coating liquid is applied to one side of a sheet-shaped separator base material (a porous sheet having a three-layer structure of PP / PE / PP with an average thickness of 20 μm) (application amount: 0.75 mg / cm ² ) and dried. To prepare a separator.
Except for using this separator, the battery No. Battery No. 1 was prepared in the same manner as in No. 1. Eleven lithium-ion secondary batteries were obtained.

<Battery No. Preparation of 12>
The mass of boehmite, Ag-containing zeolite, acrylic polymer as a binder, and CMC as a thickener, boehmite: Ag-containing zeolite: acrylic polymer: CMC = 55: 40: 2.5: 2.5. A coating liquid for forming a heat-resistant layer was prepared by mixing with ion-exchanged water in a ratio. This coating liquid is applied to one side of a sheet-shaped separator base material (a porous sheet having a three-layer structure of PP / PE / PP with an average thickness of 20 μm) (application amount: 0.75 mg / cm ² ) and dried. To prepare a separator.
Using this separator, the battery No. 1 was used except that the heat-resistant layer of the separator was made to face the positive electrode when the electrode body was manufactured. Battery No. 1 was prepared in the same manner as in No. 1. Twelve lithium-ion secondary batteries were obtained.

<Battery No. Preparation of 13>
The mass of graphite (C) as a negative electrode active material, CMC as a thickener, SBR as a binder, and Ag-containing zeolite as C: CMC: SBR: Ag-containing zeolite = 98: 1: 1: 9. A paste for forming a negative electrode active material layer was prepared by mixing with ion-exchanged water in a ratio. This paste was applied to both sides of a copper foil (negative electrode current collector) in a strip shape (application amount: 3.3 mg / cm ² per side) and dried to prepare a negative electrode.
Except for using this negative electrode, the battery No. Battery No. 1 was prepared in the same manner as in No. 1. Thirteen lithium-ion secondary batteries were obtained.

<Evaluation of initial limit current value>
No. 1-No. The 13 lithium-ion secondary batteries are placed in an environment of -10 ° C, charged for 5 seconds at a predetermined current value, paused for 10 minutes, discharged for 5 seconds, and charged / discharged for 1000 cycles with a pause of 10 minutes as one cycle. Carried out. After that, each lithium ion secondary battery was disassembled, and the presence or absence of precipitation of metallic lithium on the negative electrode was confirmed. Of the current values in which precipitation of metallic lithium was not confirmed on the negative electrode, the maximum current value was set as the limit current value. No. No. 1 when the limit current value of the lithium ion secondary battery according to No. 1 is used as a reference. 2-No. The ratio of the critical current values of the lithium ion secondary battery according to No. 13 was determined as a percentage (%). The results are shown in Table 1.

<Evaluation of limit current value after durability>
No. 1-No. The lithium ion secondary battery according to No. 13 was stored for 60 days in a high temperature environment of 75 ° C. and deteriorated. After that, No. 1-No. The lithium ion secondary battery according to No. 13 is placed in an environment of −10 ° C., charged at a predetermined current value for 5 seconds, paused for 10 minutes, discharged for 5 seconds, and charged / discharged with 1000 pauses for 10 minutes. A cycle was carried out. After that, each lithium ion secondary battery was disassembled, and the presence or absence of precipitation of metallic lithium on the negative electrode was confirmed. Of the current values in which precipitation of metallic lithium was not confirmed on the negative electrode, the maximum current value was set as the limit current value. No. No. 1 when the limit current value of the lithium ion secondary battery according to No. 1 is used as a reference. 2-No. The ratio of the critical current values of the lithium ion secondary battery according to No. 13 was determined as a percentage (%). The results are shown in Table 1.

In Table 1, the larger the value of the limit current value ratio, the higher the metal lithium precipitation resistance. No. Battery No. 1 and No. 2-No. Compared with the battery of No. 4, when ordinary zeolite (that is, Na-containing zeolite) is used, metal ions eluted from the positive electrode active material can be trapped, so that the metal lithium precipitation resistance is slightly improved. However, No. In the battery of No. 5, the metal lithium precipitation resistance deteriorated. This is because the metal ions eluted from the positive electrode active material are precipitated on the surface of the negative electrode. Therefore, even if the zeolite is placed in the negative electrode active material layer, the eluted metal ions can hardly be trapped. It is considered that this is because the negative electrode active material is mixed with a material having low electron conductivity, and the electron conductivity of the negative electrode is deteriorated.
No. 6 to No. In the battery of No. 9, Li-containing zeolite was used instead of normal zeolite (that is, Na-containing zeolite). 2-No. The same result as the battery of No. 5 was obtained.
On the other hand, No. 10-No. In the battery of No. 13, Ag-containing zeolite was used instead of normal zeolite (that is, Na-containing zeolite). 10-No. In the battery of 12, the metal lithium precipitation resistance was significantly improved. This is because the Ag-containing zeolite disposed in at least one of the positive electrode active material layer, the positive electrode active material layer surface, the separator surface, and the separator can trap the metal ions eluted from the positive electrode active material. It is considered that the Ag ions released by the ion exchange of the zeolite were reduced at the negative electrode to form an Ag film on the surface of the negative electrode active material, which reduced the resistance of the negative electrode. On the other hand, No. 2 in which Ag-containing zeolite was arranged in the negative electrode active material layer. In the 13th battery, No. The same result as the battery of No. 5 was obtained. This is because even if the Ag-containing zeolite is placed in the negative electrode active material layer, the eluted metal ions can hardly be trapped and the Ag ions are not released, and the negative electrode active material has electron conductivity. It is probable that the electron conductivity of the negative electrode deteriorated due to the mixing of low-grade ones.
From the above, the non-aqueous electrolyte secondary battery according to the present embodiment, wherein the Ag-containing zeolite is arranged in at least one of the positive electrode active material layer, the positive electrode active material layer surface, the separator surface, and the separator. It can be seen that the metal zeolite precipitation resistance during repeated charging and discharging is high.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above.

20 Winding electrode body 30 Battery case 36 Safety valve 42 Positive electrode terminal 42a Positive electrode current collector plate 44 Negative electrode terminal 44a Negative electrode current collector plate 50 Positive electrode sheet (positive electrode)
52 Positive electrode current collector 52a Positive electrode active material layer non-formed portion 54 Positive electrode active material layer 60 Negative electrode sheet (negative electrode)
62 Negative electrode current collector 62a Negative electrode active material layer non-formed portion 64 Negative electrode active material layer 70 Separator sheet (separator)
100 lithium ion secondary battery

Claims (1)

A positive electrode having a positive electrode active material layer containing a positive electrode active material, a negative electrode, and an electrode body having a separator interposed between the positive and negative electrodes.
With non-aqueous electrolyte
A non-aqueous electrolyte secondary battery containing
Ag-containing zeolite is arranged in at least one of the positive electrode active material layer, the positive electrode active material layer surface, the separator surface, and the separator.
Non-aqueous electrolyte secondary battery.

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