JP2014130729A - Method for manufacturing nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a nonaqueous electrolyte secondary battery in which a material derived from a charge carrier is suppressed from being precipitated by forming a coat of a more preferable mode on the surface of a negative electrode active material.SOLUTION: A manufacturing method of the present invention includes: a step (S10) of preparing a positive electrode and a negative electrode, while a sodium component is contained, as inevitable impurities, in at least the negative electrode; a step (S20) of forming an electrode body using the prepared positive electrode and the negative electrode; a step (S30) of forming an assembly including the electrode body accommodated within a battery case; a first injecting step (S40) of injecting a nonaqueous solvent having a dielectric constant of 10 or less into the battery case; a second injection step (S50) of, after the first injection step, injecting a nonaqueous electrolyte containing a lithium bis(oxalato)borate into the battery case; and a step (S60) of performing initial charge of the assembly.

Description

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

  Lithium ion secondary batteries and other non-aqueous electrolyte secondary batteries are becoming increasingly important as on-vehicle power supplies or personal computers and portable terminals. In particular, a lithium ion secondary battery that is lightweight and obtains a high energy density is preferable as a high-output power source mounted on a vehicle.

  By the way, in a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery, a part of the non-aqueous electrolyte is decomposed during charging, and the decomposition product is formed on the surface of the negative electrode active material (for example, natural graphite particles). A film, that is, a SEI (Solid Electrolyte Interface) film may be formed. The SEI film plays a role of protecting the negative electrode active material, but is formed by consuming charge carriers (for example, lithium ions) in the non-aqueous electrolyte. That is, since the charge carriers are fixed in the SEI film, the charge carriers can no longer contribute to the battery capacity. For this reason, the formation of a large amount of the SEI film causes a decrease in capacity retention rate (deterioration of cycle characteristics).

In order to cope with such a problem, various additives are added to the non-aqueous electrolyte in order to form a stable film on the surface of the negative electrode active material in advance instead of the SEI film. For example, Patent Document 1 describes a non-aqueous electrolyte for a secondary battery containing lithium bis (oxalato) borate (Li [B (C ₂ O ₄ ) ₂ ]) as an additive.

JP 2005-255952 A

By the way, a sodium component (for example, sodium salt) may be included as an inevitable impurity in the electrode body of a non-aqueous electrolyte secondary battery including a positive electrode and a negative electrode (for example, a negative electrode containing carboxymethyl cellulose). When an electrode body containing a sodium component as an impurity is impregnated with a non-aqueous electrolyte, the sodium component may be dissolved in the non-aqueous electrolyte. When the nonaqueous electrolytic solution containing lithium bis (oxalato) borate described in Patent Document 1 is injected into the electrode body, sodium ions (Na ⁺ ) in the nonaqueous electrolytic solution are [B (C ₂ O ₄ ). _2] ^- to spread faster than. From this, for example, when the electrode body is an electrode body formed by laminating or winding a rectangular positive electrode and negative electrode, sodium ions tend to gather at the center in the width direction perpendicular to the longitudinal direction of the electrode body. That is, the concentration of sodium ions is high at the center in the width direction. Then, [B (C ₂ O ₄ ) ₂ ] ⁻ diffuses with a delay in the central portion where the sodium ion concentration is high. For this reason, in the central part of the electrode body in the width direction, sodium ions and [B (C ₂ O ₄ ) ₂ ] ⁻ are actively associated, and Na [B (C ₂ O ₄ ) ₂ ] is an electrode. It tends to be deposited at the center in the width direction of the body. As a result, the coating amount produced by the decomposition of [B (C ₂ O ₄ ) ₂ ] may vary in the width direction of the electrode body. As described above, since a large amount of a film formed by the decomposition of [B (C ₂ O ₄ ) ₂ ] is present on the surface of the negative electrode active material at the central portion in the width direction of the electrode body, the resistance of the portion is reduced. May grow. Therefore, when charging / discharging is repeated, a substance derived from the charge carrier (for example, a metal such as metallic lithium) may be deposited at the center of the electrode body.

  The present invention has been created to solve the above-described conventional problems, and the object thereof is to suppress deposition of a substance derived from a charge carrier by forming a film having a preferable aspect on the surface of the negative electrode active material. The manufacturing method of the manufactured non-aqueous-electrolyte secondary battery is provided.

  In order to achieve the above object, the present inventor has conducted various studies, and as a result, when impregnating a non-aqueous electrolyte containing lithium bis (oxalato) borate into an electrode body containing a sodium component as an inevitable impurity, First, it has been found that the above object can be realized by impregnating an electrode body with a nonaqueous solvent having a small relative dielectric constant.

  That is, the method of manufacturing a non-aqueous electrolyte secondary battery disclosed herein is a step of preparing a positive electrode including a positive electrode active material and a negative electrode including a negative electrode active material, where at least the prepared negative electrode is unavoidable. Sodium (Na) component is contained as an impurity; a step of producing an electrode body using the prepared positive electrode and negative electrode; a step of producing an assembly in which the electrode body is housed in a battery case; relative dielectric constant A first injection step of injecting a non-aqueous solvent of 10 or less into the battery case; a second injection of a non-aqueous electrolyte containing lithium bis (oxalato) borate into the battery case after the first injection step; Injection step; and a step of initial charging the assembly to a predetermined charging voltage.

In this specification, the “non-aqueous electrolyte secondary battery” includes a non-aqueous electrolyte (typically, an electrolyte containing a supporting salt (supporting electrolyte) in a non-aqueous solvent (organic solvent)). Battery.
In the present specification, the term “secondary battery” refers to a battery that can be repeatedly charged and discharged, and is a term that includes a so-called chemical battery such as a lithium ion secondary battery and a physical battery such as an electric double layer capacitor.
Further, in the present specification, the “sodium (Na) component” is a term including a case where sodium exists alone (typically in an ionic state) and a case where it exists as a compound containing Na as a constituent element. is there.

In the method for manufacturing a non-aqueous electrolyte secondary battery provided by the present invention, a relative dielectric constant of 10 is first placed in a battery case containing an electrode body having a negative electrode containing a sodium (Na) component as an unavoidable impurity. The following nonaqueous solvent is injected, and then a nonaqueous electrolytic solution containing lithium bis (oxalato) borate is injected into the battery case.
Thus, by first injecting a nonaqueous solvent having a relative dielectric constant of 10 or less into the battery case, the nonaqueous solvent can be impregnated over the entire electrode body. At this time, the Na component in the electrode body (for example, the negative electrode) hardly elutes in the non-aqueous solvent having a relative dielectric constant of 10 or less. Therefore, the non-aqueous solvent having a relative dielectric constant of 10 or less is present in the entire electrode body. When impregnated throughout, the segregation of Na component does not occur. When a non-aqueous electrolyte containing lithium bis (oxalato) borate is injected into the battery case in a state where no segregation of the Na component occurs, the Na component in the electrode body can be eluted into the non-aqueous electrolyte. Since the electrode body is already impregnated with a non-aqueous solvent having a relative dielectric constant of 10 or less, the non-aqueous electrolyte solution can be quickly impregnated into the electrode body compared to an electrode body not impregnated with anything. it can. For this reason, segregation of the Na component (typically segregation at the center in the width direction orthogonal to the longitudinal direction of the electrode body) does not occur, and Na [B (C ₂ O ₄ ) extends over the entire width direction of the electrode body. ) ₂ ] is present. The coating formed on the surface of the negative electrode active material by the decomposition of [B (C ₂ O ₄ ) ₂ ] is in a state where variation in the coating amount in the width direction of the electrode body is suppressed (preferably the coating is almost in the width direction). A uniform state). In a non-aqueous electrolyte secondary battery including an electrode body in which variation in the coating amount is suppressed, current is prevented from being concentrated locally during charge and discharge, so that a substance derived from a charge carrier (for example, metallic lithium) Precipitation is suppressed and a non-aqueous electrolyte secondary battery excellent in cycle characteristics (for example, capacity retention rate) can be obtained.

In a preferred embodiment of the production method disclosed herein, the non-aqueous solvent having a relative dielectric constant of 10 or less is a chain carbonate, and the non-aqueous electrolyte used in the second injection step is non-aqueous. The solvent contains at least a cyclic carbonate.
Since the chain carbonate has a small relative dielectric constant, the Na component in the electrode body hardly elutes into the chain carbonate. In addition, since the cyclic carbonate has a large relative dielectric constant, lithium bis (oxalato) borate is easily dissolved in the cyclic carbonate. For this reason, lithium bis (oxalato) borate can be easily diffused over the entire electrode body.

In another preferred embodiment of the production method disclosed herein, the non-aqueous electrolyte used in the second injection step is a non-aqueous solvent having a relative dielectric constant of 10 or less used in the first injection step. including.
In the second injection step, since the nonaqueous solvent having a relative dielectric constant of 10 or less used in the first injection step is used, the nonaqueous electrolytic solution is impregnated into the entire electrode body at an early stage.

In another preferred embodiment of the production method disclosed herein, carboxymethyl cellulose is used as a thickener contained in the negative electrode.
Since the negative electrode containing carboxymethyl cellulose tends to contain a large amount of sodium (Na) component as an unavoidable impurity, when the electrode body is impregnated with a non-aqueous electrolyte containing lithium bis (oxalato) borate, the center part of the electrode body Na [B (C ₂ O ₄ ) ₂ ] can be precipitated in large amounts. For this reason, when carboxymethyl cellulose is used, first, a nonaqueous solvent having a relative dielectric constant of 10 or less is injected into the battery case, and then a nonaqueous electrolytic solution containing lithium bis (oxalato) borate is injected into the battery case. The effect of adopting the configuration of the present invention can be particularly exhibited.

In another preferred embodiment of the production method disclosed herein, a lithium transition metal composite oxide is used as the positive electrode active material.
Since lithium transition metal composite oxides tend to contain a large amount of sodium (Na) component as an unavoidable impurity, when impregnated with a non-aqueous electrolyte containing lithium bis (oxalato) borate, Na is formed at the center of the electrode body. [B (C ₂ O ₄ ) ₂ ] can be precipitated in large amounts. Therefore, when a lithium transition metal composite oxide is used, a nonaqueous solvent having a relative dielectric constant of 10 or less is first injected into the battery case, and then a nonaqueous electrolyte containing lithium bis (oxalato) borate is added to the battery case. The effect by adopting the configuration of the present invention of injecting into the inside can be particularly exhibited.

In another preferred embodiment of the production method disclosed herein, the electrode body is an electrode body in which a positive electrode formed in a sheet shape and a negative electrode formed in a sheet shape are overlapped, and the electrode body A wound electrode body wound in the longitudinal direction is used.
In the wound electrode body having such a configuration, the non-aqueous electrolyte is impregnated from both ends in the width direction (winding axis direction) of the wound electrode body toward the center. For this reason, the sodium component tends to segregate in the central portion of the wound electrode body. Therefore, when a wound electrode body is used, a nonaqueous solvent having a relative dielectric constant of 10 or less is first injected into the battery case, and then a nonaqueous electrolyte containing lithium bis (oxalato) borate is injected into the battery case. In particular, the effect of adopting the configuration of the present invention can be exhibited.

Moreover, according to the present invention, as another aspect for realizing the above object, a non-aqueous electrolyte secondary battery manufactured by any of the manufacturing methods disclosed herein is provided.
In a non-aqueous electrolyte secondary battery (for example, a lithium ion secondary battery) obtained by any of the production methods disclosed herein, the coating produced by the decomposition of [B (C ₂ O ₄ ) ₂ ] is a negative electrode Since the surface of the active material is formed in a preferable state (a state in which there is little or no variation in the coating amount), precipitation of a material derived from the charge carrier (for example, metallic lithium) is prevented, and the battery performance is excellent. It can be a secondary battery. For this reason, it can be used as a drive power source for vehicles (typically automobiles, particularly automobiles equipped with electric motors such as hybrid cars, electric cars, and fuel cell cars). As another aspect of the present invention, non-aqueous electrolyte secondary batteries (for example, 40 to 80 batteries) obtained by any of the manufacturing methods disclosed herein are typically connected in series. A vehicle including the battery pack as a driving power source is provided.

It is a perspective view which shows typically the external shape of the non-aqueous-electrolyte secondary battery which concerns on one Embodiment of this invention. It is sectional drawing which follows the II-II line | wire in FIG. It is a flowchart for demonstrating the manufacturing method of the nonaqueous electrolyte secondary battery which concerns on one Embodiment of this invention. It is a side view which shows typically the vehicle (automobile) provided with the nonaqueous electrolyte secondary battery which concerns on this invention. It is a top view which shows typically the structure of the negative electrode used in the case of the measurement of the boron content in a film.

  Hereinafter, preferred embodiments of the present invention will be described. It should be noted that matters other than matters specifically mentioned in the present specification and necessary for carrying out the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field. Hereinafter, the case of a lithium ion secondary battery may be described in more detail as a typical example, but the application target of the present invention is not intended to be limited to such a battery.

  As a preferred embodiment of a method for producing a non-aqueous electrolyte secondary battery disclosed herein, a method for producing a lithium ion secondary battery will be described in detail as an example. Is not intended to be limited to such types of secondary batteries. For example, the present invention can also be applied to a non-aqueous electrolyte secondary battery using other metal ions (for example, magnesium ions) as a charge carrier.

  As shown in FIG. 3, the manufacturing method of the lithium ion secondary battery (non-aqueous electrolyte secondary battery) disclosed herein includes a positive / negative electrode preparation step (S10), an electrode body preparation step (S20), It includes a three-dimensional manufacturing step (S30), a first injection step (S40), a second injection step (S50), and an initial charging step (S60).

≪Positive electrode preparation process (S10) ≫
First, the positive and negative electrode preparation step (S10) will be described. In the present embodiment, as the positive and negative electrode preparation step, a positive electrode including a positive electrode active material and a negative electrode including a negative electrode active material are prepared. In a preferred embodiment, the method further includes preparing a separator disposed between the positive electrode and the negative electrode. Here, at least the prepared negative electrode contains a sodium (Na) component as an unavoidable impurity. Typically, the prepared positive electrode, negative electrode, and separator contain a sodium (Na) component as an inevitable impurity.

  The negative electrode of the lithium ion secondary battery disclosed herein includes a negative electrode current collector and a negative electrode mixture layer including at least a negative electrode active material formed on the surface of the negative electrode current collector. The negative electrode mixture layer can contain optional components such as a binder and a thickener as needed in addition to the negative electrode active material.

  As the negative electrode current collector, a conductive member made of a metal having good conductivity is preferably used, like the current collector used in the negative electrode of a conventional lithium ion secondary battery. For example, copper, nickel, or an alloy mainly composed of them can be used. The shape of the negative electrode current collector can vary depending on the shape or the like of the lithium ion secondary battery, and is not particularly limited, and may be various forms such as a foil shape, a sheet shape, a rod shape, and a plate shape.

As the negative electrode active material, one kind or two or more kinds of materials conventionally used for lithium ion secondary batteries can be used without particular limitation. For example, a particulate (or spherical, scale-like) carbon material including a graphite structure (layered structure) at least partially, a lithium transition metal composite oxide (for example, a lithium titanium composite oxide such as Li ₄ Ti ₅ O ₁₂ ), Lithium transition metal composite nitride, etc. Examples of the carbon material include natural graphite, artificial graphite (artificial graphite), non-graphitizable carbon (hard carbon), graphitizable carbon (soft carbon), and the like. The average particle diameter of the negative electrode active material is, for example, in the range of about 1 μm to 50 μm (usually 5 μm to 30 μm), which is based on various commercially available laser diffraction / scattering methods. The median diameter (D50: 50% volume average particle diameter) that can be derived from the particle size distribution measured based on the particle size distribution measuring device. For example, a negative electrode active material at least partially coated with an amorphous carbon film can be obtained by mixing a negative electrode active material with a pitch and baking it.

  As said binder, the thing similar to the binder used for the negative electrode of a general lithium ion secondary battery can be employ | adopted suitably. For example, when an aqueous paste composition is used to form the negative electrode mixture layer, a water-soluble polymer material or a water-dispersible polymer material can be preferably used. Examples of the water dispersible polymer include rubbers such as styrene butadiene rubber (SBR); polyethylene oxide (PEO), vinyl acetate copolymer and the like. Styrene butadiene rubber is preferably used. Here, since styrene butadiene rubber is used in a state of being dispersed in water, carbon dioxide is dissolved in water during storage, and the styrene butadiene rubber aqueous dispersion (SBR aqueous dispersion) becomes acidic. If an acidic SBR aqueous dispersion is used, the negative electrode current collector may be corroded. Therefore, an alkali metal hydroxide (for example, sodium hydroxide) is added to the SBR aqueous dispersion for neutralization. It has been broken. When sodium hydroxide is used during neutralization, a large amount of sodium (Na) component is contained as an impurity in the formed negative electrode.

  The “aqueous paste-like composition” is a concept indicating a composition using water or a mixed solvent mainly composed of water as a dispersion medium for the negative electrode active material. As the solvent other than water constituting the mixed solvent, one or two or more kinds of non-aqueous solvents (lower alcohol, lower ketone, etc.) that can be uniformly mixed with water can be appropriately selected and used.

  As the thickener, for example, a water-soluble or water-dispersible polymer can be adopted. Examples of the water-soluble polymer include cellulose polymers such as carboxymethylcellulose (CMC), methylcellulose (MC), cellulose acetate phthalate (CAP), and hydroxypropylmethylcellulose (HPMC); polyvinyl alcohol (PVA); . In addition, the same materials as those mentioned as the binder can be appropriately employed. Preferably, carboxymethylcellulose is used. Since the negative electrode containing carboxymethyl cellulose tends to contain a large amount of sodium (Na) component as an unavoidable impurity, when impregnated in a non-aqueous electrolyte, a large amount of sodium ions can be eluted in the non-aqueous electrolyte. For this reason, the effect by employ | adopting the structure of this invention of inject | pouring the nonaqueous solvent whose relative dielectric constant is 10 or less in a battery case in the 1st injection | pouring process mentioned later can be exhibited especially.

  The negative electrode disclosed here can be suitably manufactured, for example, generally by the following procedure. A paste-like composition for forming a negative electrode mixture layer is prepared by dispersing the above-described negative electrode active material and other optional components (binder, thickener, etc.) in an appropriate solvent (for example, water). . A negative electrode comprising a negative electrode current collector and a negative electrode mixture layer formed on the negative electrode current collector by applying the prepared composition to the negative electrode current collector, drying, and then compressing (pressing) the negative electrode current collector. Can be produced. The negative electrode produced in this way can contain a sodium (Na) component as an unavoidable impurity. In the present embodiment, the sodium (Na) component as an unavoidable impurity means an element that can be dissolved in the non-aqueous electrolyte. The same applies hereinafter unless otherwise specified.

  The positive electrode of the lithium ion secondary battery disclosed here includes a positive electrode current collector and a positive electrode mixture layer including at least a positive electrode active material formed on the surface of the positive electrode current collector. The positive electrode mixture layer may contain an optional component such as a conductive material and a binder (binder) in addition to the positive electrode active material.

  As the positive electrode current collector, aluminum or an aluminum alloy mainly composed of aluminum is used as in the case of the positive electrode current collector used in the positive electrode of a conventional lithium ion secondary battery. The shape of the positive electrode current collector can be the same as the shape of the negative electrode current collector.

Examples of the positive electrode active material include materials capable of inserting and extracting lithium ions, and include lithium-containing compounds (for example, lithium transition metal composite oxides) containing a lithium element and one or more transition metal elements. For example, lithium nickel composite oxide (for example, LiNiO ₂ ), lithium cobalt composite oxide (for example, LiCoO ₂ ), lithium manganese composite oxide (for example, LiMn ₂ O ₄ ), or lithium nickel cobalt manganese composite oxide (for example, LiNi _{1). / 3} Co _1/3 Mn _1/3 O ₂ ), a ternary lithium-containing composite oxide.
In addition, a polyanionic compound (for example, LiFePO ₄₎ whose general formula is represented by LiMPO _4, LiMVO _4, or Li ₂ MSiO ₄ (wherein M is at least one element of Co, Ni, Mn, and Fe), etc. ₄ , LiMnPO ₄ , LiFeVO ₄ , LiMnVO ₄ , Li ₂ FeSiO ₄ , Li ₂ MnSiO ₄ , Li ₂ CoSiO ₄ ) may be used as the positive electrode active material.

The positive electrode active material may be manufactured by various methods. The case where the positive electrode active material is a lithium nickel cobalt manganese composite oxide will be described as an example. For example, a hydroxide containing Ni, Co, and Mn at a target molar ratio (for example, Ni _1/3 Co _1/3 NiCoMn composite hydroxide represented by Mn _1/3 (OH) ₂ is prepared, mixed and fired so that the molar ratio of the hydroxide to the lithium source becomes the target value, thereby lithium nickel cobalt Manganese composite oxide can be obtained. The NiCoMn composite hydroxide can be preferably prepared by, for example, a coprecipitation method. The firing is typically performed in an oxidizing atmosphere (for example, in the air). The firing temperature is preferably 700 ° C to 1000 ° C. In the coprecipitation method, for example, since a NiCoMn composite hydroxide is prepared using sodium hydroxide having a relatively high concentration, the lithium nickel cobalt manganese composite oxide produced as described above has a sodium component as an impurity. (For example, Na ₂ SO ₄ ).

  The conductive material is not limited to a specific conductive material as long as it is conventionally used in this type of lithium ion secondary battery. For example, carbon materials such as carbon powder and carbon fiber can be used. As the carbon powder, various carbon blacks (for example, acetylene black, furnace black, ketjen black, etc.), carbon powders such as graphite powder can be used. Among these, acetylene black (AB) is a preferable carbon powder. Such conductive materials can be used singly or in appropriate combination of two or more.

  As said binder (binder), the thing similar to the binder used for the positive electrode of a common lithium ion secondary battery can be employ | adopted suitably. For example, when a solvent-based paste-like composition (a paste-like composition includes a slurry-like composition and an ink-like composition) is used as the composition for forming the positive electrode mixture layer, a polyfluoride is used. Polymer materials that are soluble in a non-aqueous solvent (organic solvent) such as vinylidene chloride (PVDF) and polyvinylidene chloride (PVDC) can be used. Alternatively, when an aqueous paste composition is used, a water-soluble (soluble in water) polymer material or a water-dispersible (water-dispersible) polymer material can be preferably used. For example, polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR) and the like can be mentioned. In addition, the polymer material illustrated above may be used as a thickener or other additives in the above composition in addition to being used as a binder.

  Here, the “solvent-based paste-like composition” is a concept indicating a composition in which the dispersion medium of the positive electrode active material is mainly a non-aqueous solvent. As the non-aqueous solvent, for example, N-methyl-2-pyrrolidone (NMP) can be used.

  The positive electrode disclosed here can be suitably manufactured, for example, generally by the following procedure. A paste-like composition for forming a positive electrode mixture layer is prepared by dispersing the above-described positive electrode active material, conductive material, and a binder that is soluble in a nonaqueous solvent in a nonaqueous solvent. A positive electrode comprising a positive electrode current collector and a positive electrode mixture layer formed on the positive electrode current collector by applying the prepared composition to the positive electrode current collector, drying, and then compressing (pressing) the positive electrode current collector. Can be produced. The positive electrode produced in this way can contain a sodium (Na) component as an unavoidable impurity.

  A conventionally well-known thing can be especially used as said separator without a restriction | limiting. For example, a porous sheet made of resin (a microporous resin sheet) can be preferably used. A porous polyolefin resin sheet such as polyethylene (PE) or polypropylene (PP) is preferred. For example, a PE sheet, a PP sheet, a sheet having a three-layer structure (PP / PE / PP structure) in which PP layers are laminated on both sides of the PE layer, and the like can be suitably used. Since many separators contain a sodium component as a plasticizer, when the separator is impregnated with a non-aqueous electrolyte, the sodium component dissolves in the non-aqueous electrolyte.

≪Electrode body production process (S20) ≫
Next, the electrode body manufacturing step (S20) will be described. In the electrode body manufacturing step, an electrode body is manufactured using the prepared positive electrode and negative electrode. Typically, an electrode body is produced using the prepared positive electrode, negative electrode and separator.
An electrode body (for example, a stacked electrode body or a wound electrode body) of a lithium ion secondary battery disclosed herein includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. Yes. Here, the positive electrode formed in a sheet shape, the negative electrode formed in a sheet shape, and a wound electrode body (a wound electrode body) including the separator sheet will be described as an example. It is not intended to be limited to.

FIG. 2 shows a wound electrode body 50 according to the present embodiment. As shown in FIG. 2, the wound electrode body 50 is wound in the longitudinal direction in a state where a sheet-like positive electrode 64 and a sheet-like negative electrode 84 are laminated with a total of two long separators 90 interposed therebetween. Then, the flat wound electrode body 50 is produced by crushing the obtained wound body from the side direction and causing it to be ablated.
At the time of the above lamination, the positive electrode mixture layer non-formed portion of the positive electrode 64 (that is, the portion where the positive electrode current collector 62 is exposed without the formation of the positive electrode mixture layer 66) 63 and the negative electrode mixture layer of the negative electrode 84 are not formed. The positive electrode 64 and the negative electrode 84 are arranged in the width direction so that the formation portion (that is, the portion where the negative electrode current collector 82 is not formed without forming the negative electrode mixture layer 86) 83 protrudes from both sides in the width direction of the separator 90. Slightly shift and overlap. As a result, in the lateral direction with respect to the winding direction of the wound electrode body 50, the electrode mixture layer non-formed portions 63 and 83 of the positive electrode 64 and the negative electrode 84 are respectively wound core portions (that is, the positive electrode mixture layer 66 and the positive electrode 64). The negative electrode composite material layer 86 of the negative electrode 84 and the two separators 90 are closely wound around). A positive electrode terminal 60 (for example, made of aluminum) is joined to the positive electrode mixture layer non-formed portion 63 to electrically connect the positive electrode 64 and the positive electrode terminal 60 of the wound electrode body 50 formed in the flat shape. Similarly, a negative electrode terminal 80 (for example, made of nickel) is joined to the negative electrode mixture layer non-forming portion 83 to electrically connect the negative electrode 84 and the negative electrode terminal 80. The positive and negative electrode terminals 60 and 80 and the positive and negative electrode current collectors 62 and 82 can be joined by, for example, ultrasonic welding, resistance welding, or the like.

Void volume (void volume) V1 of the wound electrode body 50 is composed of a pore volume [cm ^3] of the cathode 64, the void volume of the anode 84 [cm ^3], the void volume of the separator 90 [cm ^3] members a pore volume V2 of itself, be determined from the sum of the total pore volume V3 of the pore volume [cm ^3] between the void volume [cm ^3] and the negative electrode 84 and the separator 90 between the positive electrode 64 and the separator 90 it can. That is, V1 = V2 + V3.

Void volume of the positive electrode sheet 64 (pore volume) [cm ^3], for example, from the apparent volume of the positive-electrode mixture layer 66 [cm ^3], the volume of the positive electrode active material [cm ^3], a conductive material and a binder It is calculated | required by subtracting the volume [cm < ³ >] of submaterials, such as. Void volume of the negative electrode 84 (pore volume) [cm ^3], for example, from the apparent volume of the negative-electrode mixture layer 90 [cm ^3], the volume of the anode active material [cm ^3], a binder and a thickener It is calculated | required by subtracting the volume [cm < ³ >] of submaterials, such as. The void volume [cm ³ ] of the separator 90 is obtained, for example, by the product of the apparent volume [cm ³ ] of the separator and the porosity (percentage of holes) [%]. Here, the porosity [%] is, for example, the mass Ws of the separator sheet, the apparent volume Vs of the separator sheet, and the true density ρ _s of the separator sheet (the mass Ws divided by the actual volume not including the voids). Value) and the porosity [%] = (1−Ws / ρ _s Vs) × 100.

  The total void volume V3, for example, gradually increases the amount of nonaqueous electrolyte injected into the battery case 15 containing the wound electrode body 50, and the AC impedance of the battery after injection of the nonaqueous electrolyte is increased. Measure and determine the amount of electrolyte injected into a battery with a reduced AC impedance (that is, a state where the entire wound electrode body 50 is impregnated with the electrolyte). And it can obtain | require by subtracting the space | gap volume V2 of the member itself of this wound electrode body 50 from this calculated | required amount of electrolyte solution.

<< Assembly manufacturing process (S30) >>
Next, the assembly manufacturing process (S30) will be described. In the present embodiment, the fabricated electrode body 50 is accommodated in the battery case 15 to produce the assembly 70.

  As shown in FIGS. 1 and 2, the battery case 15 of the present embodiment is a battery case made of metal (for example, made of aluminum, and also preferably made of resin or laminate film), and the upper end is open. A case body (exterior case) 30 having a flat bottomed box shape (typically a rectangular parallelepiped shape) and a lid body 25 that closes the opening 20 of the case body 30 are provided. On the upper surface of the battery case 15 (that is, the lid body 25), a positive electrode terminal 60 that is electrically connected to the positive electrode 64 of the wound electrode body 50 and a negative electrode terminal that is electrically connected to the negative electrode 84 of the wound electrode body 50. 80 is provided. The lid 25 has a non-aqueous solvent (first injection step) having a relative dielectric constant (εr) of 10 or less, which is described later, in the case body 30 (battery case 15) in which the wound electrode body 50 is accommodated, lithium An injection port 45 for injecting a nonaqueous electrolytic solution (second injection step) containing bis (oxalato) borate is formed. The injection port 45 is sealed with a sealing plug 48 after a second injection step (S50) described later. Further, as in the case of the conventional lithium ion secondary battery, the lid 25 is provided with a safety valve 40 for discharging the gas generated inside the battery case 15 to the outside of the battery case 15 when the battery is abnormal. ing. The wound electrode body 50 is placed in a case in a posture in which the wound axis of the wound electrode body 50 is laid down (that is, the opening 20 is formed in the normal direction of the wound axis of the wound electrode body 50). Housed in the main body 30. Thereafter, the opening portion 20 of the case body 30 is sealed with the lid body 25, thereby producing the assembly 70. The lid 25 and the case body 30 are joined by welding or the like.

≪First injection process (S40) ≫
Next, the first injection step (S40) will be described. In the present embodiment, as the first injection process, a nonaqueous solvent having a relative dielectric constant of 10 or less is injected into the battery case 15. The nonaqueous solvent (organic solvent) used in the first injection step is not particularly limited as long as the relative dielectric constant (εr) is 10 or less. Examples of the nonaqueous solvent having a relative dielectric constant of 10 or less include dimethyl carbonate (DMC) having a relative dielectric constant of 2.8, diethyl carbonate (DEC) having a relative dielectric constant of 2.8, and a relative dielectric constant of 2. A chain carbonate such as ethyl methyl carbonate (EMC) which is 9, tetrahydrofuran (THF) whose dielectric constant is 7.25, cyclic ether such as 1,4-dioxane whose dielectric constant is 2.2, dielectric constant A chain ether such as dimethoxyethane (DME) having a dielectric constant of 7.26, diethyl ether having a dielectric constant of 4.27, 1,3-dioxolane having a dielectric constant of 5.78, and a dielectric constant of 4.5. Methyl formate, and 2-methyltetrahydrofuran having a relative dielectric constant of 5.24. Such non-aqueous solvents can be used alone or in combination of two or more. The nonaqueous solvent to be injected in the first injection step is preferably a nonaqueous solvent having a relative dielectric constant of 5 or less.

  The injection amount of the nonaqueous solvent having a relative dielectric constant of 10 or less injected into the battery case 15 in the first injection step is at least the void volume (space volume) V1 of the wound electrode body 50. In addition, the nonaqueous solvent injection amount [g] in the first injection step was 100% by mass based on the total amount [g] of the nonaqueous solvent injected into the battery case 15 in the first injection step and the second injection step. Sometimes, it is preferably determined to be 20% by mass to 50% by mass (for example, 35% by mass to 45% by mass).

  After injecting the non-aqueous solvent having a relative dielectric constant of 10 or less into the battery case 15, the pressure in the battery case 15 is increased (pressure impregnation) or decreased (pressure impregnation), or a combination thereof (ie, pressurization). Impregnation and reduced pressure impregnation) are preferred. At this time, the inlet 45 may be temporarily sealed with the sealing plug 48. For example, in the case of reduced pressure impregnation, the relative dielectric constant of the wound electrode body 50 is 10 or less under a reduced pressure of 5 KPa to 30 KPa (atmospheric pressure is 100 KPa), and in the case of pressurized impregnation, under a high pressure of 400 KPa to 1000 KPa. Impregnation with a non-aqueous solvent. Thereby, the wound electrode body 50 can be impregnated with the non-aqueous solvent having a relative dielectric constant of 10 or less at an early stage.

«Second injection step (S50)»
Next, the second injection process will be described. In the present embodiment, non-aqueous electrolysis including lithium bis (oxalato) borate (Li [B (C ₂ O ₄ ) ₂ ]) (hereinafter sometimes abbreviated as “LiBOB”) as the second injection step. The liquid is poured into the battery case 15. Although it does not specifically limit, in the whole non-aqueous electrolyte solution which totaled the non-aqueous solvent with a relative dielectric constant of 10 or less injected in the first injection step and the non-aqueous electrolyte solution injected in the second injection step The concentration of lithium bis (oxalato) borate is, for example, 0.01 mol / L to 0.2 mol / L (for example, 0.05 mol / L to 0.2 mol / L).

  The nonaqueous electrolytic solution used in the second injection step is obtained by dissolving a supporting salt in a suitable nonaqueous solvent. Examples of the nonaqueous solvent used in the second injection step include, in addition to the nonaqueous solvent used in the first injection step, ethylene carbonate (EC) having a relative dielectric constant (εr) of 95.3, a relative dielectric constant, and the like. Non-aqueous solvents having a relative dielectric constant greater than 10, such as cyclic carbonates such as propylene carbonate (PC) having a relative dielectric constant of 39.1, and cyclic esters such as γ-butyrolactone having a relative dielectric constant of 39.1. Such non-aqueous solvents can be used alone or in combination of two or more. From the viewpoint of preferably dissolving a support salt described later in a non-aqueous solvent, the non-aqueous solvent used in the second injection step preferably includes a non-aqueous solvent having a relative dielectric constant of 30 or more. Moreover, it is preferable that the nonaqueous electrolytic solution used in the second injection step includes a nonaqueous solvent having a relative dielectric constant of 10 or less used in the first injection step.

Examples of the supporting salt include lithium salts such as LiPF ₆ , LiClO ₄ , LiAsF ₆ , Li (CF ₃ SO ₂ ) ₂ N, LiBF ₄ , and LiCF ₃ SO ₃ . These supporting salts can be used alone or in combination of two or more. LiPF ₆ is particularly preferable. The concentration of the supporting salt is not particularly limited, but if it is too low, the amount of charge carriers (typically lithium ions) contained in the non-aqueous electrolyte is insufficient, and the ionic conductivity tends to decrease. On the other hand, when the concentration is extremely high, the viscosity of the non-aqueous electrolyte increases in a temperature range below room temperature (for example, 0 ° C. to 30 ° C.), and ion conductivity tends to decrease. For this reason, the concentration of the supporting salt is, for example, 0.1 mol / L or more (for example, 0.8 mol / L or more) and preferably 2 mol / L or less (for example, 1.5 mol / L or less).

  The injection amount [g] of the nonaqueous solvent in the second injection step is 100% by mass when the total amount [g] of the nonaqueous solvent injected into the battery case 15 in the first injection step and the second injection step is 100% by mass. 50% by mass to 80% by mass (for example, 55% by mass to 65% by mass) is preferable.

  After injecting the non-aqueous electrolyte containing LiBOB into the battery case 15, as in the first injection step, the pressure in the battery case 15 is increased (pressure impregnation) or decreased (pressure impregnation), or A combination (ie pressure impregnation and vacuum impregnation) is preferred.

≪Initial charging process (S60) ≫
Next, the initial charging step (S60) will be described. In the present embodiment, the assembly 70 is charged to a predetermined charging voltage, thereby forming a film derived from lithium bis (oxalato) borate on the surface of the negative electrode active material in the negative electrode mixture layer 86.

In this step, for example, the assembly 70 is charged at a charging rate of about 0.1 C to 2 C up to an upper limit voltage (e.g., 3.7 V to 4.1 V) when the battery is used. During this initial charge, [B (C ₂ O ₄ ) ₂ ] in the electrode body is decomposed, and the coating derived from [B (C ₂ O ₄ ) ₂ ] is the surface of the negative electrode active material in the negative electrode mixture layer 86. The coating film formed on the surface of the negative electrode active material in the width direction orthogonal to the longitudinal direction of the negative electrode mixture layer 86 is formed in a preferable state. After charging the assembly 70, it is preferable to discharge to a predetermined voltage (for example, 3V to 3.2V) at a discharge rate of about 0.1C to 2C. Moreover, it is preferable to repeat the said charging / discharging several times (for example, 3 times). By performing the charging / discharging process on the assembly 70 in this manner, the assembly 70 becomes a usable battery, that is, a lithium ion secondary battery (non-aqueous electrolyte secondary battery) 10 (FIGS. 1 and 2). reference). “1C” means the amount of current that can charge the battery capacity (Ah) predicted from the theoretical capacity of the positive electrode in one hour.

  Next, the lithium ion secondary battery (nonaqueous electrolyte secondary battery) 10 manufactured by the manufacturing method disclosed herein will be described.

  As shown in FIG. 2, the lithium ion secondary battery 10 according to the present embodiment includes a stacked or wound electrode body 50 (here, a wound electrode body) 50 including a positive electrode 64 and a negative electrode 84, and a non-aqueous electrolyte. And. LiBOB that has not been decomposed in the charge / discharge step may remain in the non-aqueous electrolyte. The positive electrode 64 includes a positive electrode current collector 62 and a positive electrode mixture layer 66 including at least a positive electrode active material formed on the surface of the positive electrode current collector 62. The negative electrode 84 includes a negative electrode current collector 82 and a negative electrode mixture layer 86 including at least a negative electrode active material formed on the surface of the negative electrode current collector 82.

  Thus, in the first injection step (S40), by injecting a non-aqueous solvent having a relative dielectric constant of 10 or less into the battery case 15, the Na component in the wound electrode body 50 is almost eluted into the non-aqueous solvent. Without this, the nonaqueous solvent is impregnated throughout the wound electrode body 50. Then, in the second injection step (S50) in a state where the Na component is hardly eluted from the wound electrode body 50, a nonaqueous electrolytic solution containing lithium bis (oxalato) borate (typically including a supporting salt). Is injected into the battery case 15 to impregnate the wound electrode body 50. As a result, the Na component is eluted from the wound electrode body 50 into the nonaqueous electrolytic solution, but the Na component is not segregated, and the Na component is present throughout the wound electrode body 50. Thereby, it is suppressed that the coating film derived from lithium bis (oxalato) borate becomes locally large. That is, a film derived from lithium bis (oxalato) borate is satisfactorily formed over the entire wound electrode body 50 (typically, the surface of the negative electrode active material). As described above, in the lithium ion secondary battery 10 including the wound electrode body 50 in which the variation in the coating amount is suppressed, current is prevented from being concentrated locally during charging and discharging, so that deposition of metallic lithium is suppressed. Is done.

  EXAMPLES Examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples.

<Example 1>
[Preparation of positive electrode]
The mass ratio of LiNi _1/3 Co _1/3 Mn _1/3 O ₂ as the positive electrode active material, acetylene black (AB) as the conductive material, and PVDF as the binder is 100: 6: 3. Thus, these materials were dispersed in NMP to prepare a paste-like composition for forming a positive electrode mixture layer. The composition was applied to a positive electrode current collector (aluminum foil) having a thickness of 15 μm at a coating amount of 45 mg / cm ² per side and dried, and then subjected to a press treatment so that the mixture density was on the positive electrode current collector. A sheet-like positive electrode A on which a positive electrode mixture layer of 2.9 g / cm ³ was formed was prepared (positive electrode preparation step). The thickness of the positive electrode A (including the positive electrode current collector) was 170 μm, the length of the positive electrode mixture layer in the width direction was 94 mm, and the length of the positive electrode A in the longitudinal direction was 4500 mm.

[Preparation of negative electrode]
Graphite, SBR as a binder, and CMC as a thickener are weighed so that the mass ratio is 100: 1: 1, and these materials are dispersed in water to form a paste-like negative electrode mixture layer A composition was prepared. The composition was applied on a negative electrode current collector (copper foil) having a thickness of 10 μm and coated at a coating amount of 22 mg / cm ² on one side and dried, and then subjected to press treatment so that the mixture density was 1 on the negative electrode current collector. A sheet-like negative electrode A on which a negative electrode mixture layer of 0.7 g / cm ³ was formed was prepared (negative electrode preparation step). The thickness of the negative electrode A (including the positive electrode current collector) was 140 μm, the length of the negative electrode mixture layer in the width direction was 100 mm, and the length of the negative electrode A in the longitudinal direction was 4700 mm.

  The prepared positive electrode A, the prepared negative electrode A, and two separator sheets having a thickness of 20 μm (polypropylene / polyethylene / polypropylene three-layer structure) were overlapped and wound to produce a wound electrode body (electrode) Body production process). Electrode terminals are joined to the ends of the positive and negative electrode current collectors of the wound electrode body, and the wound electrode body is placed in an aluminum battery case having a length of 75 mm, a width of 120 mm, a thickness of 15 mm, and a case thickness of 1 mm. The assembly which concerns on Example 1 was produced by accommodating (assembly production process).

Next, a nonaqueous solvent having a relative dielectric constant of 10 or less was injected into the battery case of the assembly according to Example 1, and the wound electrode body was impregnated with the nonaqueous solvent (first injection step). In the first injection step, a mixed solvent of 20.6 g of DMC having a relative dielectric constant (εr) of 2.8 and 19.4 g of EMC having a relative dielectric constant of 2.9 (volume ratio of DMC to EMC is 1: 1) is injected. did. Next, a non-aqueous electrolyte containing lithium bis (oxalato) borate (LiBOB) was injected into the battery case, and the wound electrode body was impregnated with the non-aqueous electrolyte (second injection step). In the second injection step, a mixed solvent of EC 38.1 g having a relative dielectric constant of 95.3, 20.6 g of DMC having a relative dielectric constant of 2.8, and 9.7 g of EMC having a relative dielectric constant of 2.9 (EC and DMC and The volume ratio of EMC was 3: 2: 1), and 1.9 g of LiBOB as an additive and 14.6 g of LiPF ₆ as a supporting salt were injected. Here, the concentration of LiBOB in the non-aqueous electrolyte in the total of the non-aqueous solvent injected in the first injection step and the non-aqueous electrolyte injected in the second injection step is 0.1 mol / L, and LiPF The concentration of ₆ was 1 mol / L. Further, the nonaqueous solvent in the nonaqueous electrolyte in the total of the nonaqueous solvent injected in the first injection step and the nonaqueous electrolyte injected in the second injection step is a volume ratio of EC, DMC, and EMC. Was a 3: 4: 3 mixed solvent.

  After the second injection step, the assembly according to Example 1 was charged for the first time. That is, charging was performed at a constant current up to 4.1 V at a charging rate of 1 C (24 A) under a temperature condition of 25 ° C. After the first charge, the battery was stored for 1 week under a temperature condition of 60 ° C. In this way, a lithium ion secondary battery according to Example 1 having a battery capacity of 24 Ah, including a negative electrode in which a coating film derived from lithium bis (oxalato) borate was formed on the surface of the negative electrode active material was produced.

<Example 2 to Example 7>
Lithium ions according to Examples 2 to 7 are the same as Example 1 except that the nonaqueous solvent or nonaqueous electrolyte to be injected in the first injection process and the second injection process is changed to those shown in Tables 1 and 2. A secondary battery was produced. In the production of the lithium ion secondary battery according to Example 3, a nonaqueous electrolytic solution containing PC having a relative dielectric constant of 64.4 was used in the second injection step. In the production of the lithium ion secondary battery according to Example 4, a nonaqueous solvent containing DEC having a relative dielectric constant of 2.8 was used in the first injection step.

[Measurement of boron content]
About the lithium ion secondary battery which concerns on Examples 1-7 after the said preservation | save, it discharged with the constant current to 3V at the discharge rate of 1C (24A) on 25 degreeC temperature conditions. Thereafter, the lithium ion secondary battery according to Examples 1 to 7 was disassembled, the negative electrode of each secondary battery was taken out, and the boron content in the coating formed on the surface of the negative electrode active material in the negative electrode mixture layer [% By mass] was measured. Specifically, as shown in FIG. 5, the length of the negative electrode mixture layer 186 of each negative electrode 184 near the middle between the innermost circumference and the outermost circumference of the extracted negative electrode is cut to 100 mm in the longitudinal direction. The negative electrode mixture layer 186 was peeled from the negative electrode current collector 182 at intervals of 5 mm from the center X in the width direction of the negative electrode mixture layer 186 and divided into 10 samples (a to j in FIG. 5). . Then, the amount of boron [μg] in each sample was quantitatively analyzed by ICP emission spectroscopy, and the amount of boron relative to the solid content of the negative electrode mixture layer in each sample was calculated. Here, the following formula {(boron amount) / (solid content of negative electrode composite material layer)} was defined as the boron content [mass%]. About the lithium ion secondary battery which concerns on each example, the average of boron content [mass%] of sample a, b, c, h, i, and j shall be 100 mass%, and boron content of each sample aj with respect to this The ratio of [% by mass] was determined. Table 3 shows the measurement results.

As shown in Table 3, lithium ion secondary batteries manufactured by injecting a non-aqueous electrolyte composed of a non-aqueous solvent having a relative dielectric constant of 10 or less into the battery case in the first injection step (Examples 1 to 4) Then, it was confirmed that boron content is substantially equivalent over the whole width direction of a negative electrode compound-material layer. That is, in the lithium ion secondary batteries according to Examples 1 to 4, there is almost no variation in the coating amount in the width direction of the negative electrode mixture layer, and the coating film is formed almost uniformly over the entire width direction of the negative electrode mixture layer. It was confirmed that
On the other hand, in the lithium ion secondary batteries (Examples 5 to 7) manufactured by injecting a nonaqueous electrolytic solution containing a nonaqueous solvent having a relative dielectric constant greater than 10 into the battery case in the first injection step, It was confirmed that the boron content was increased in the central part of the material layer in the width direction (d to g in FIG. 5, especially e and f). That is, in the lithium ion secondary batteries according to Examples 5 to 7, the coating amount varies in the width direction of the negative electrode mixture layer, and the coating film is excessively formed in the central portion of the negative electrode mixture layer in the width direction. It was confirmed.

[Capacity maintenance rate measurement]
About the lithium ion secondary batteries according to Examples 1 to 7 after the storage, after charging at a constant current up to 4.1 V at a charge rate of 1 C (24 A) under a temperature condition of 25 ° C., and after a 10-minute pause, Discharge was performed at a constant current up to 3 V at a discharge rate of 1 C (24 A). The discharge capacity obtained at this time was used as the initial capacity. About the lithium ion secondary battery which concerns on Example 1- Example 7 after an initial stage capacity | capacitance measurement, charging / discharging was repeated 100 cycles and the capacity | capacitance maintenance factor [%] after 100 cycles was calculated | required. The charge / discharge conditions for one cycle are 0 ° C. under a temperature of 1C (24A) and charged at a constant current up to 4.1V. After a 10-minute pause, the discharge rate of 1C (24A) is up to 3V. The battery was discharged at a constant current and paused for 10 minutes. For the lithium ion secondary batteries according to Examples 1 to 7 after 100 cycles, charging was performed at a constant current up to 4.1 V at a charging rate of 1 C (24 A) under a temperature condition of 25 ° C. Thereafter, discharge was performed at a constant current up to 3 V at a discharge rate of 1 C (24 A). The discharge capacity obtained at this time was taken as the capacity after the cycle. The ratio of the capacity after 100 cycles to the initial capacity ((capacity after 100 cycles / initial capacity) × 100 (%)) was calculated as the capacity retention ratio (%). Table 4 shows the measurement results.

[Confirmation of lithium precipitation]
Furthermore, the lithium ion secondary batteries according to Examples 1 to 7 after the capacity retention rate measurement were disassembled, and the negative electrodes according to the respective examples were taken out. At this time, the presence or absence of deposition of metallic lithium in the central portion in the width direction of the negative electrode was examined. Table 4 shows the measurement results.

  As shown in Table 4, lithium ion secondary batteries (Examples 1 to 4) manufactured by injecting a nonaqueous electrolytic solution made of a nonaqueous solvent having a relative dielectric constant of 10 or less into the battery case in the first injection step. Then, compared with lithium ion secondary batteries (Example 5 to Example 7) produced by injecting a non-aqueous electrolyte containing a non-aqueous solvent having a relative dielectric constant greater than 10 into the battery case in the first injection step, It was confirmed that the capacity maintenance rate was large. This is considered to be because in the lithium ion secondary batteries according to Examples 1 to 4, the coating was formed substantially uniformly over the entire width direction of the negative electrode mixture layer. Moreover, although the deposition of metallic lithium was not confirmed in the lithium ion secondary batteries according to Examples 1 to 4, the deposition of metallic lithium was confirmed in the lithium ion secondary batteries according to Examples 5 to 7. This is considered to be because, in the lithium ion secondary batteries according to Examples 5 to 7, an excessive film was formed in the central portion in the width direction of the negative electrode mixture layer, and the resistance of the portion was increased.

  The non-aqueous electrolyte secondary battery obtained by the manufacturing method according to the present invention is mounted on a vehicle such as an automobile, in particular, because precipitation of substances derived from charge carriers is suppressed and battery performance (for example, capacity retention rate) is excellent. It can be suitably used as a power source for a motor (electric motor). Therefore, the present invention, as schematically shown in FIG. 4, is a vehicle (typically) including such a lithium ion secondary battery 10 (typically, a battery pack 200 formed by connecting a plurality of the batteries 10 in series) as a power source. Is provided with an automobile, particularly an automobile equipped with an electric motor such as a hybrid vehicle, an electric vehicle, and a fuel vehicle.

10 Lithium ion secondary battery (non-aqueous electrolyte secondary battery)
15 Battery Case 20 Opening 25 Lid 30 Case Body 40 Safety Valve 45 Inlet 48 Sealing Plug 50 Winding Electrode Body 60 Positive Terminal 62 Positive Electrode Current Collector 63 Positive Electrode Mixing Layer Non-Forming Portion 64 Positive Electrode 66 Positive Electrode Mixing Layer 70 Assembly 80 Negative electrode terminal 82 Negative electrode current collector 83 Negative electrode composite material layer non-formed portion 84 Negative electrode 86 Negative electrode composite material layer 90 Separator 100 Vehicle (automobile)
200 batteries

Claims (6)

A method of manufacturing a non-aqueous electrolyte secondary battery,
A step of preparing a positive electrode including a positive electrode active material and a negative electrode including a negative electrode active material, wherein at least the prepared negative electrode includes a sodium (Na) component as an unavoidable impurity;
Producing an electrode body using the prepared positive and negative electrodes;
Producing an assembly in which the electrode body is housed in a battery case;
A first injection step of injecting a nonaqueous solvent having a relative dielectric constant of 10 or less into the battery case;
A second injection step of injecting a non-aqueous electrolyte containing lithium bis (oxalato) borate into the battery case after the first injection step; and
Performing initial charging of the assembly to a predetermined charging voltage;
A method for producing a non-aqueous electrolyte secondary battery. The non-aqueous solvent having a relative dielectric constant of 10 or less is a chain carbonate,
The said nonaqueous electrolyte solution used in a said 2nd injection | pouring process is a manufacturing method of Claim 1 containing a cyclic carbonate at least as a nonaqueous solvent.   The manufacturing method according to claim 1 or 2, wherein the nonaqueous electrolytic solution used in the second injection step includes a nonaqueous solvent having a relative dielectric constant of 10 or less used in the first injection step.   The manufacturing method as described in any one of Claim 1 to 3 which uses carboxymethylcellulose as a thickener contained in the said negative electrode.   The manufacturing method according to any one of claims 1 to 4, wherein a lithium transition metal composite oxide is used as the positive electrode active material.   The electrode body in which a positive electrode formed in a sheet shape and a negative electrode formed in a sheet shape are superimposed as the electrode body, and a wound electrode body wound in the longitudinal direction of the electrode body is used. The manufacturing method as described in any one of 1 to 5.

Images