JP2014157748A - 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, by which a coating can be formed on an active material layer without causing unevenness.SOLUTION: The method for manufacturing a nonaqueous electrolyte secondary battery disclosed herein includes the steps of: (a) kneading a negative electrode active material and an oxalate complex compound with a predetermined solvent to prepare a negative electrode paste A; (b) kneading a negative electrode active material with a predetermined solvent without containing an oxalate complex compound to prepare a negative electrode paste B; (c) coating the negative electrode paste B on a central strip-like region which is a negative electrode active material layer formation region on a long negative electrode collector and includes the center in the width direction orthogonal to the longitudinal direction of the negative electrode active material layer formation region; (d) coating the negative electrode paste A on a region which is the negative electrode active material layer formation region and excludes the central strip-like region; (e) constructing an electrode body using a negative electrode coated with the negative electrode pastes A and B; and (f) constructing a battery by accommodating the electrode body and a nonaqueous electrolyte in a battery case.

Description

  The present invention relates to a method for producing a non-aqueous electrolyte secondary battery containing an oxalato complex compound in a non-aqueous electrolyte.

  A non-aqueous electrolyte secondary battery such as a lithium ion secondary battery is smaller, lighter, and has a higher energy density than an existing battery, and can be excellent in output density. Therefore, it is preferably used as a so-called portable power source such as a personal computer or a portable terminal, or a vehicle-mounted power source (vehicle power source). This type of battery is typically constructed such that a wound electrode body, in which a positive electrode and a negative electrode are laminated in an insulating state and wound, and a non-aqueous electrolyte are housed in a battery case. Each of the positive electrode and the negative electrode is provided with an electrode active material layer mainly composed of a material (active material) capable of reversibly occluding and releasing charge carriers (typically lithium ions) on a corresponding current collector. Then, charge and discharge are performed as charge carriers move back and forth between the electrodes.

In a non-aqueous electrolyte secondary battery, a part of components (for example, a non-aqueous solvent and a supporting salt) contained in the non-aqueous electrolyte during decomposition is decomposed, and the SEI film containing the decomposition product on the surface of the active material of the positive and negative electrodes (Solid Electrolyte Interphase film; for example, an organic material layer such as ROCO ₂ Li or an inorganic material layer such as LiF or Li ₂ O) may be formed. Such SEI film suppresses subsequent decomposition of the non-aqueous electrolyte and elution of elements constituting the active material, so that battery performance (for example, durability) can be improved. However, since charge carriers (for example, lithium ions) consumed by the formation of the SEI film have an irreversible capacity, the formation of such a film may cause a decrease in battery capacity.
Therefore, a technique is known in which an additive that can be decomposed at a lower potential than the nonaqueous electrolytic solution to form a stable film on the surface of the active material is contained in the battery. For example, Patent Document 1 discloses a non-aqueous electrolyte secondary battery that includes an oxalato complex compound (for example, lithium bis (oxalato) borate) as a film forming agent in a non-aqueous electrolyte.

JP 2005-255952 A

  By the way, the electrode body of a nonaqueous electrolyte secondary battery contains a sodium (Na) component (for example, sodium salt) as an inevitable impurity. For example, when carboxymethyl cellulose (CMC) is used as a thickener when forming the active material layer of the negative electrode, such a sodium component can be uniformly contained in the negative electrode active material layer. The sodium component dissolves in the non-aqueous electrolyte when the negative electrode active material layer is impregnated with the non-aqueous electrolyte. Thicken. Therefore, for example, when the electrode body is an electrode body formed by laminating or further winding a flat positive electrode and a negative electrode, sodium ions of the negative electrode active material layer start to penetrate from the end in the width direction, That is, typically, they tend to gather at the center in the width direction orthogonal to the longitudinal direction. Therefore, in the negative electrode active material layer, sodium ions are unevenly distributed in the central portion in the width direction, and the concentration tends to increase.

Here, as the nonaqueous electrolytic solution, when an electrolytic solution containing oxalite, for example, an electrolytic solution containing lithium bis (oxalato) borate (LiBOB) is used, bis (oxalato) borate anion ([B (C ₂ O ₄ ) ₂ ] ⁻ ) has a slower diffusion rate than sodium ion (Na ⁺ ) which is a cation. Therefore, since the bis (oxalato) borate anion arrives at this central part where sodium ions are unevenly distributed, it often encounters sodium ions only when the central part is reached. Therefore, in this central part, association of sodium ion (Na ⁺ ) and bis (oxalato) borate anion ([B (C ₂ O ₄ ) ₂ ] ⁻ ) is actively performed, and hardly soluble Na [B (C _A large amount of ₂ O ₄ ) ₂ ] is precipitated. As a result, in the width direction of the negative electrode active material layer, a large amount of Na [B (C ₂ O ₄ ) ₂ ] tends to be deposited in the center, and Na [B (C ₂ O ₄ ) ₂ ] or non-charged during the first charge is not observed. Even in the formation of a LiBOB-derived film formed by decomposing [B (C ₂ O ₄ ) ₂ ] ⁻ in the water electrolyte, unevenness occurred in the width direction. When a secondary battery is used for a long period of time, a portion having a small LiBOB-derived film is likely to deteriorate, and a resistance of a portion having a large LiBOB-derived film can be increased. Therefore, when charging / discharging is repeated, a substance (for example, a metal such as metallic lithium (Li)) derived from the charge carrier is locally present in a portion having a high resistance in the central portion in the width direction of the negative electrode active material layer. It was deposited. In particular, lithium secondary batteries that use LiBOB as an additive for the nonaqueous electrolyte solution are liable to precipitate Li during low-temperature use, so there is a concern that the capacity may further decrease.

  The present invention has been made in view of such circumstances, and since a film derived from an oxalato complex compound such as LiBOB can be uniformly formed on the negative electrode active material layer, durability is enhanced and further low temperature characteristics are improved. An object of the present invention is to provide a method for producing a non-aqueous electrolyte secondary battery. Another related object is to provide a non-aqueous electrolyte secondary battery in which such a film is uniformly formed and the functionality is enhanced.

  According to the present invention, a method for producing a non-aqueous electrolyte secondary battery is provided. The method includes the following steps: (a) a step of kneading a negative electrode active material and an oxalato complex compound with a predetermined solvent to prepare a negative electrode paste A; (b) an oxalate complex compound not contained, A step of preparing a negative electrode paste B by kneading with a predetermined solvent, and (c) the negative electrode paste B in a negative electrode active material layer forming region on a long negative electrode current collector, A step of applying to a central band-like region including the center of the width direction (hereinafter sometimes simply referred to as “width direction”) orthogonal to the longitudinal direction; (d) the negative electrode paste A in the negative electrode active material layer forming region; A step of applying to a region excluding the central band region, (e) a step of constructing an electrode body using a negative electrode to which the negative electrode pastes A and B are applied, and (f) the electrode body, Non-aqueous electrolyte and battery case Constructing a battery with capacity including,. In addition, said (a)-(f) can also be understood as a method of manufacturing the negative electrode provided with the negative electrode active material layer on the negative electrode collector.

In order to eliminate the influence of the uneven distribution of the sodium component that occurs when the non-aqueous electrolyte permeates, the present inventors have made a negative electrode active material layer other than the region in which the sodium component is unevenly distributed before the initial charge when the film is formed. By disposing a component of the oxalato complex compound (typically, it may be an oxalato complex ion) that can be a raw material of the film in the formation region, the film formed by the reductive decomposition of the oxalato complex compound can be uniformly distributed. As a result, the present invention has been completed.
That is, in the above manufacturing method, the negative electrode paste B containing no oxalato complex compound is applied to the central band region where the sodium component can be unevenly distributed due to the permeation of the non-aqueous electrolyte, and the negative electrode paste containing the oxalato complex compound to other regions. A is applied. According to such a configuration, the oxalato complex component can be present uniformly (particularly uniformly in the width direction) without unevenness in the negative electrode active material layer before the initial charge, and a uniform film can be formed on the surface of the negative electrode active material by the initial charge. Can be formed. Therefore, the decomposition of the nonaqueous electrolytic solution and the deterioration of the active material in the subsequent charge / discharge can be suitably suppressed, and a battery having excellent durability can be realized. In addition, since a uniform film is formed on the surface of the negative electrode active material, the problem of capacity reduction during low temperature use can be solved.

  In this specification, “non-aqueous electrolyte secondary battery” refers to a battery provided with a non-aqueous electrolyte (typically, an electrolyte containing a supporting salt in a non-aqueous solvent). A battery is a typical example. Further, in this specification, the “lithium ion secondary battery” refers to a secondary battery that uses lithium ions as electrolyte ions and is charged and discharged by movement of lithium ions between the positive and negative electrodes. A secondary battery generally referred to as a lithium ion secondary battery, a lithium polymer battery, a lithium ion capacitor, or the like is a typical example included in the lithium ion secondary battery in this specification. In the present specification, the “active material” refers to a substance (composition) capable of reversibly occluding and releasing chemical species (lithium ions in a lithium ion secondary battery) serving as a charge carrier in the positive electrode or the negative electrode. Further, in the present specification, the “paste” may include a slurry or an ink form.

In a preferred embodiment of the manufacturing method disclosed herein, the width of the central strip region is 8 mm or more and 12 mm or less.
The uneven distribution of the sodium component itself due to the permeation of the non-aqueous electrolyte is caused by, for example, the non-aqueous electrolyte permeating from both ends in the width direction of the negative electrode active material layer near the center, the dimensions of the negative electrode, It is hardly affected by the substantial concentration of the sodium component. Therefore, the width of the central strip region can be set within the above-described range.

The preferable aspect of the manufacturing method disclosed here WHEREIN: The said negative electrode paste A contains an oxalato complex compound in the ratio of 1-10 mass parts with respect to 100 mass parts of negative electrode active materials, It is characterized by the above-mentioned.
By setting the amount of the oxalato complex compound in the above range, an appropriate amount of SEI film can be formed on the surface of the negative electrode active material layer. That is, deterioration of the negative electrode active material can be suitably suppressed, and an increase in internal resistance can be suppressed without the SEI film being formed too thick.

In a preferred embodiment of the production method disclosed herein, at least one of the negative electrode paste A and the negative electrode paste B contains a thickener.
In the preparation of the negative electrode paste, the thickener is preferably used as an additive capable of controlling the applicability of the paste, but at the same time, it can be a material containing a large amount of sodium components that cause film unevenness. Since this invention can suppress suitably the generation | occurrence | production of the film | membrane nonuniformity by this sodium component, when employ | adopting the mixing | blending which adds a thickener to a negative electrode paste, the effect is exhibited clearly.

In a preferred embodiment of the production method disclosed herein, the oxalato complex compound is added to the non-aqueous electrolyte.
In the production method of the present invention, it is not always necessary to add the oxalato complex compound, which is a raw material of the film, to the non-aqueous electrolyte. For example, by adding the oxalato complex compound to the non-aqueous electrolyte, the positive electrode The SEI film can be formed also on the surface of the active material layer.

  In a preferred embodiment of the production method disclosed herein, lithium bis (oxalato) borate (hereinafter sometimes abbreviated as “LiBOB”) represented by the following formula (I) among the oxalato complex compounds. It is characterized by using. LiBOB can form a film having excellent stability on the surface of the negative electrode active material. Therefore, the decomposition of the non-aqueous electrolyte accompanying the subsequent charge / discharge, the deterioration of the negative electrode active material, and the like can be suitably suppressed, and the effects of the present invention can be exhibited at a higher level.

In a preferred embodiment of the manufacturing method disclosed herein, the method further includes a step of performing a conditioning for discharging to a predetermined discharge voltage after charging the battery constructed as described above to a predetermined charge voltage, a battery that has been subjected to the conditioning, the central element of the negative electrode active when the concentration C _a of the central element of the oxalato complex compound and 100 at the ends in the width direction of the material layer, the oxalate complex compound in the central strip region concentration C _B is characterized by configured to be in the range of 90 to 110.
According to the manufacturing method of this aspect, since the coating is uniformly formed in the width direction of the negative electrode active material layer (specifically, the surface of the negative electrode), variation in resistance in the negative electrode active material layer is suppressed, and the charge carrier Generation | occurrence | production of the precipitate originating in can be suppressed. Therefore, for example, when the battery is repeatedly charged and discharged, a battery that exhibits excellent durability can be manufactured.

  The production method disclosed herein can be particularly preferably applied when graphite is used as the negative electrode active material. The formation of a uniform coating in the width direction as described above can favorably suppress the deterioration when graphite is used as the negative electrode active material. Therefore, even in such a configuration, a battery that exhibits excellent durability can be manufactured when the battery is repeatedly charged and discharged.

As another aspect of the present invention, a non-aqueous electrolyte secondary battery is provided. Such a battery has an electrode body in which a long positive electrode having a positive electrode active material layer containing an upper positive electrode active material and a negative electrode having a long negative electrode active material layer containing a negative electrode active material are laminated via a separator. However, it is accommodated in the battery case together with the non-aqueous electrolyte. And the said negative electrode active material layer is equipped with the membrane | film | coat derived from an oxalato complex compound at least in part. Here, such a battery, when the concentration C _A of the central element of the oxalato complex compound at the end in the width direction perpendicular to the longitudinal direction of the negative electrode active material layer is 100, in the longitudinal direction of the negative electrode active material layer The concentration C _B of the central element of the oxalato complex compound in the central band region including the center in the orthogonal width direction is in the range of 90 to 110.

  In the battery having such a configuration, a film is uniformly formed in the width direction of the negative electrode active material layer. For this reason, the local increase in resistance due to coating unevenness on the surface of the negative electrode active material layer is eliminated, and the deposition of the substance derived from the charge carrier can be suppressed. Therefore, the durability can be increased without increasing the resistance of the negative electrode, and further, the low temperature characteristics can be improved. The battery having such a configuration can be particularly suitably manufactured by the method disclosed above.

  In addition, according to the production method disclosed herein, the effect of adding a film-forming agent is appropriately exhibited, and a non-aqueous electrolyte secondary that can stably exhibit high performance (for example, durability and low-temperature characteristics). A battery is provided. Such a non-aqueous electrolyte secondary battery can suppress, for example, a decrease in capacity at a low temperature and can maintain its input / output characteristics over a long period of time. For example, a hybrid vehicle (HV), a plug-in hybrid, etc. It can be suitably used as a drive power source for vehicles such as automobiles (PHV) and electric cars (EV).

It is a flowchart which shows the manufacturing method of the nonaqueous electrolyte secondary battery which concerns on one Embodiment. It is a perspective view which shows typically the external shape of the nonaqueous electrolyte secondary battery based on one Embodiment. It is the III-III sectional view taken on the line of FIG. It is a schematic diagram which shows the structure of the winding electrode body of the nonaqueous electrolyte secondary battery based on one Embodiment. It is a figure explaining the extraction position of the negative electrode active material layer in an Example.

  Hereinafter, while describing suitable embodiment of the manufacturing method of the non-aqueous-electrolyte secondary battery disclosed here, the non-aqueous-electrolyte secondary battery of this invention is also demonstrated collectively. Matters necessary for implementation other than matters specifically mentioned in the present specification can be grasped as design matters of those skilled in the art based on the prior art in the field. The non-aqueous electrolyte secondary battery having such a structure and the manufacturing method thereof can be implemented based on the contents disclosed in the present specification and the common general technical knowledge in the field.

Hereinafter, the non-aqueous electrolyte secondary battery and the manufacturing method thereof according to the present invention will be described in detail with reference to a case of a lithium ion secondary battery as a typical example, but the application target of the present invention is limited to such a battery. It is not a thing.
In the manufacturing process of the non-aqueous electrolyte secondary battery, the present inventors have found that uneven formation of the film on the surface of the negative electrode active material layer due to the uneven distribution of the sodium component that occurs when the non-aqueous electrolyte penetrates into the electrode body. In order to solve the problem, I was conducting intensive research. As a result, prior to the initial charge when the film is formed, by placing an oxalato complex compound that can be a raw material of the film in the negative electrode active material layer forming region other than the region where the sodium component is unevenly distributed, The present inventors have found that the film can be formed uniformly and uniformly by reductive decomposition of the complex compound, and the present invention has been completed.

Therefore, in the production method of the present invention, the negative paste B that does not contain the oxalato complex compound is applied to the central strip region where the sodium component can be unevenly distributed due to the permeation of the non-aqueous electrolyte, and the oxalato complex compound is applied to the other regions. By applying the negative electrode paste A containing, the oxalato complex compound is uniformly arranged in the whole negative electrode active material layer to be formed.
In other words, the non-aqueous electrolyte secondary battery manufacturing method disclosed herein essentially includes the following steps as illustrated in the flowchart of FIG.
(A) Step of preparing negative electrode paste A by kneading a negative electrode active material and an oxalato complex compound with a predetermined solvent (b) Negative electrode paste containing no oxalato complex compound and kneading the negative electrode active material with a predetermined solvent Step of preparing B (c) The negative electrode paste B is a negative electrode active material layer forming region on a long negative electrode current collector, and the center in the width direction perpendicular to the longitudinal direction of the negative electrode active material layer forming region is (D) Step of applying the negative electrode paste A to the negative electrode active material layer forming region except for the central band region (e) Application of the negative electrode pastes A and B Step of constructing electrode body using negative electrode formed (f) Step of housing a battery case containing the electrode body and a non-aqueous electrolyte In addition, the steps (a) to (f) The negative electrode active material on the negative electrode current collector It may also grasped as a method for producing a negative electrode having a layer. As long as the step (d) is performed after the step (a) and the step (c) is performed after the step (b), the steps (a) to (d) are in any order and timing. May be implemented. Steps (e) and (f) may be performed in sequence after steps (a) to (d). Hereinafter, each process is demonstrated in order.

<< Step a: Preparation of negative electrode paste A >>
In step a, a negative electrode paste A containing an oxalato complex compound that can be said to be a raw material for film formation is prepared. In this step, at least the negative electrode active material and the oxalato complex compound are kneaded in a predetermined solvent. In consideration of coatability, coating film formability, and the like, for example, a binder, a thickener, and various additives conventionally used for this type of negative electrode paste are added to the negative electrode paste A. can do.

<Negative electrode active material>
As the negative electrode active material, one type or two or more types of materials conventionally used in lithium ion secondary batteries can be used without any particular limitation. For example, a carbon particle is mentioned as a suitable negative electrode active material. A particulate carbon material (carbon particles) containing a graphite structure (layered structure) at least partially is preferably used. Any carbon material of a so-called graphitic material (graphite), non-graphitizable carbon material (hard carbon), easily graphitized carbon material (soft carbon), or a combination of these materials is preferably used. obtain. Among these, graphite particles such as natural graphite can be preferably used.

<Oxalato complex compound>
As the oxalato complex compound, one or two or more kinds can be used without particular limitation from those prepared by various known methods and various products that are generally available. As such compounds, various salts of oxalite complexes, derivatives thereof, and the like can be considered. An oxalite complex is an ionic complex formed by coordination bond of at least one oxalate ion (C ₂ O ₄ ²⁻ ) with a central element (also referred to as a coordination atom). The central element is not particularly limited as long as it is an element capable of forming such an ionic oxalite complex. For example, it is represented by a metalloid element typified by boron (B) or the like, or fluorine (F) or the like. Nonmetallic elements, noble metal elements typified by platinum (Pt), transition metal elements typified by cobalt (III), iron (III) and the like are exemplified.
As such an oxalato complex compound, for example, a compound having a structure in which an oxalate ion as a ligand is coordinated to boron (B) or fluorine (F) as a central element is preferable. ), That is, an oxalatoborate complex compound is more preferable.
As such an oxalatoborate complex compound, a compound represented by the following formula (II) or (III) is typically exemplified.

Here, R ₁ and R ₂ in the formula (II) are a halogen atom (for example, F, Cl, Br, preferably F) and a perfluoroalkyl group having 1 to 10 (preferably 1 to 3) carbon atoms. Can be selected independently from each other. A ⁺ in formulas (II) and (III) may be either an inorganic cation or an organic cation. Specific examples of the inorganic cation include alkali metal cations such as Li, Na, and K, alkaline earth metal cations such as Be, Mg, and Ca, Ag, Zn, Cu, Co, Fe, Ni, Mn, Examples thereof include cations of metals such as Ti, Pb, Cr, V, Ru, Y, lanthanoids and actinoids, protons, and the like. Specific examples of the organic cation include tetraalkylammonium ions such as tetrabutylammonium ion, tetraethylammonium ion and tetramethylammonium ion, trialkylammonium ions such as triethylmethylammonium ion and triethylammonium ion, other pyridinium ions and imidazolium. Ion, tetraethylphosphonium ion, tetramethylphosphonium ion, tetraphenylphosphonium ion, triphenylsulfonium ion, triethylsulfonium ion, and the like. Examples of preferred cations include lithium ions, tetraalkylammonium ions and protons.

In a preferred embodiment disclosed herein, a compound represented by the formula (III) can be used as the oxalato complex compound. Of these, lithium bis (oxalato) borate (LiBOB) represented by the formula (I) is a preferred example. LiBOB can form a strong and stable film on the active material surface. Therefore, the decomposition reaction of the nonaqueous electrolytic solution and the deterioration of the negative electrode active material accompanying the subsequent charge / discharge can be suitably suppressed. Further, the bis (oxalato) borate anion ([B (C ₂ O ₄ ) ₂ ] ⁻ ) generated by lithium dissociation of LiBOB has a lower diffusion rate than the sodium component that can be contained in the negative electrode as described later, and the sodium Forms poorly soluble sodium bis (oxalato) borate (NaBOB) in association with the components. The production method of the present invention can be preferably applied to the case where the above-described LiBOB is used as the oxalato complex compound because the disadvantage caused by the segregation of NaBOB can be preferably eliminated.

<Binder, thickener>
As the binder, one or two or more of various organic polymers (polymers) conventionally used in nonaqueous electrolyte secondary batteries can be used as long as they can be dissolved or dispersed in the solvent used for kneading. It can be used without any particular limitation. For example, polyvinylidene fluoride (PVdF), polyvinylidene chloride (PVdC), polyvinyl fluoride (PVF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-par Halogenated polymers such as fluoroalkyl vinyl ether copolymer (PFA); nitrile polymers such as polyacrylonitrile (PAN) and polymethacrylonitrile; polyalkyl (meth) acrylates such as polymethyl methacrylate and polymethyl acrylate and their derivatives Imide polymers such as polyamideimide and polyimide; ethylene polymers such as polyethylene oxide (PEO); polymers such as polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA); Lil-based polymers; urethane polymer such as polyurethane, alkyl trimethyl ammonium Niu These polymeric materials, in addition to use as a binder or thickening can be used as other additives of the negative electrode paste.

<Other additives>
Furthermore, although not essential, the negative electrode paste A prepared here may contain various additives such as a dispersant and a gas generating additive as long as the effects of the present invention are not impaired.

<Solvent>
Although it does not specifically limit as long as the material used for preparation of said negative electrode paste can disperse | distribute or melt | dissolve uniformly, For example, it is one of the solvents conventionally used for manufacture of a nonaqueous electrolyte secondary battery. Species or two or more can be used. Such solvents can be broadly classified into organic solvents and aqueous solvents. As the organic solvent, for example, an amide solvent, an alcohol solvent, a ketone solvent, an ester solvent, an amine solvent, an ether solvent, a nitrile solvent, a cyclic ether solvent, an aromatic hydrocarbon solvent, or the like is used. Can do. More specifically, N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide, N, N-dimethylacetamide, 2-propanol, ethanol, methanol, acetone, methyl ethyl ketone, methyl propenoate, cyclohexanone, acetic acid Methyl, ethyl acetate, methyl acrylate, diethyltriamine, N, N-dimethylaminopropylamine, acetonitrile, ethylene oxide, tetrahydrofuran, dioxane, benzene, toluene, ethylbenzene, xylene dimethyl sulfoxide, dichloromethane, trichloromethane, dichloroethane, etc. Typically, NMP can be used. In addition, the aqueous solvent is preferably water or a mixed solvent mainly composed of water. As the solvent other than water constituting the mixed solvent, one or more organic solvents (lower alcohol, lower ketone, etc.) that can be uniformly mixed with water can be appropriately selected and used. For example, it is preferable to use an aqueous solvent in which 80% by mass or more (more preferably 90% by mass or more, more preferably 95% by mass or more) of the aqueous solvent is water. From various viewpoints such as reduction of environmental burden and reduction of waste, a particularly preferable example is an aqueous solvent (for example, water) substantially composed of water.

  These materials are appropriately adjusted so that the ratio of the negative electrode active material to the entire negative electrode active material layer (that is, the total mass of the solid content of the negative electrode paste) is about 50% by mass or more, preferably 90%. Mass% to 99 mass% (for example, 95 mass% to 99 mass%).

  Further, although the ratio of the oxalato complex compound blended in the negative electrode active material layer may vary depending on, for example, the type and properties (for example, particle size and specific surface area) of the negative electrode active material, it cannot be strictly defined. For example, the amount is suitably about 1 to 10 parts by weight, preferably about 1 to 5 parts by weight with respect to parts by weight. If the amount of the oxalato complex compound is too small, the effect of suppressing the unevenness of the film formed on the negative electrode active material layer may not be sufficiently obtained. This is not preferable because the amount of the film formed on the active material layer is too large and the resistance is increased. When a binder is used, the proportion of the binder in the negative electrode active material layer can be set to, for example, 1 part by mass to 10 parts by mass with respect to 100 parts by mass of the negative electrode active material, and is usually about 1 part by mass to 5 parts by mass. It is appropriate to use parts by mass.

  In addition, the compounding quantity of a thickener and a solvent can be suitably set considering the applicability | paintability, coating-film formation property, etc. of the negative electrode paste A. For example, the solid content concentration of the negative electrode paste A is not particularly limited because it depends on the amount of the thickener and the like, but as an approximate guideline, for example, 40 mass% to 65 mass% (preferably 45 mass% to 55 mass%). , More preferably 45 mass% to 50 mass%).

  For kneading the material constituting the negative electrode paste A, various known stirring and mixing devices such as a ball mill, a roll mill, a mixer, a disper, and a kneader can be used. The kneading may be performed so that these materials are uniformly dispersed. For example, a specific example is a method of kneading a part of a solvent and an additive such as a negative electrode active material, an oxalato complex compound, a thickener and the like, then diluting with the remaining solvent, and finally mixing a binder. The Although the preferable kneading time in the preparation of such a negative electrode paste varies depending on the apparatus and kneading conditions used and cannot be generally stated, it can generally be about 10 minutes to 3 hours, for example, 10 minutes to 30 hours. It can be on the order of minutes.

<< Step b: Preparation of negative electrode paste B >>
In the process b, the negative electrode paste B which does not contain said oxalato complex compound is prepared. That is, the negative electrode paste B can typically be configured by removing the oxalato complex compound from the negative electrode paste A. Therefore, in step b, at least the negative electrode active material is kneaded with a predetermined solvent. In consideration of the coating properties and coating film formability of the negative electrode paste B, for example, a binder, a thickener, various additives conventionally used for this type of negative electrode paste, and the like are added. May be. About the material which comprises the negative electrode paste B, the thing similar to what was shown by said negative electrode paste A can be used except the point which does not use an oxalato complex compound, The compounding can also be determined similarly. . The kneading of the material constituting the negative electrode paste B can be carried out in the same manner as in the case of the negative electrode paste A described above.

<< Step c: Application of negative electrode paste B >>
In step c, the negative electrode paste B is a negative electrode active material layer forming region on a long negative electrode current collector, and a central strip region including the center in the width direction orthogonal to the longitudinal direction of the negative electrode active material layer forming region Apply to.
As the negative electrode current collector, a conductive member made of a metal having good conductivity (for example, copper, nickel, titanium, stainless steel, etc.) can be preferably used. The shape of the current collector is not particularly limited because it differs depending on the shape of the battery to be constructed. For example, a rod-like body, a plate-like body, a foil-like body, a net-like body, or the like can be considered. In addition, in a battery provided with the winding electrode body mentioned later, a foil-like body is mainly used. The thickness of the foil current collector is not particularly limited, but a thickness of about 5 μm to 50 μm can be used, more preferably about 8 μm to 30 μm, in view of the balance between the capacity density of the battery and the strength of the current collector. is there.

  In such a negative electrode current collector, a negative electrode active material layer forming region for forming a negative electrode active material layer can be set. For example, the negative electrode current collector can be provided with an uncoated portion where a negative electrode active material layer is not formed in order to improve current collection efficiency. Such an uncoated portion can typically be provided in a strip shape at one end extending in the longitudinal direction of the long negative electrode current collector. Further, the negative electrode active material layer forming region can be the entire surface of the negative electrode current collector excluding the uncoated portion. This negative electrode active material layer formation region may be formed only on one surface of the negative electrode current collector, or may be formed on both surfaces.

In this negative electrode active material layer formation region, a central strip region including the center in the width direction perpendicular to the longitudinal direction can be further set. Such a central belt-like region is preferably located at the center in the width direction of the negative electrode active material layer forming region. Further, the width of the central strip region is not strictly limited, but is preferably in the range of more than 6 mm and less than 14 mm, and more preferably, for example, 8 mm or more and 12 mm or less. Such a value is hardly influenced by the dimension of the negative electrode (negative electrode active material layer forming region), the substantial concentration of the sodium component, and the like. Therefore, the width of the central strip region can be determined as an absolute value as described above.
For the application of the negative electrode paste B, for example, a conventionally known coating apparatus such as a slit coater, a die coater, a comma coater, or a gravure coater can be used.

<< Step d: Application of negative electrode paste A >>
In step d, the negative electrode paste A is applied to the negative electrode active material layer formation region except the central band region. For the application of the negative electrode paste A, similarly to the application of the paste B, for example, a conventionally known coating apparatus such as a slit coater, a die coater, a comma coater, or a gravure coater can be used.

In addition, either said process c and process d may be implemented first, and may be implemented simultaneously. For example, using a slit die coater, a slot die coater, or two die coaters, the negative electrode paste A is applied in two stripes so that the coating pattern has a stripe shape sandwiching the central strip region, and then the central strip shape is applied. The negative electrode paste B may be applied to the region (gap).
Alternatively, for example, after applying the negative electrode paste B to the central band region, the negative electrode paste A is applied in two stripes by a slit die coater, a slot die coater, or two die coaters so as to sandwich the central band region. You may make it work.
Furthermore, the negative electrode pastes A and B may be applied simultaneously by using a slit die coater, a slot die coater, or three die coaters.

  In addition, about the negative electrode paste A and B apply | coated to the negative electrode collector as above-mentioned, Preferably, a solvent can be removed with a suitable drying method. As such a technique, natural drying, drying with hot air, low humidity air, vacuum, freezing, infrared rays, far infrared rays, electron beams, or the like can be performed alone or in combination.

  In the negative electrode pastes A and B applied on the negative electrode current collector, the concentration of the oxalato complex compound is slightly homogenized (leveled) by an action such as diffusion at the interface (for example, a width of about 1 mm). That is, it can be said that the concentration of the oxalato complex compound is inclined at the interface between the negative electrode pastes A and B. However, in the negative electrode after such negative electrode pastes A and B are applied and dried, the concentration of the oxalato complex compound in the central band region and other regions is clearly different. That is, the oxalato complex compound is essentially not contained in the central band region of the negative electrode active material layer, and the oxalato complex compound is typically 1 part by mass to 10 parts by mass with respect to 100 parts by mass of the negative electrode active material in other regions. It is included at a ratio of about part by mass. In addition, said "other area | region" is an area | region where the negative electrode paste A is apply | coated. Specifically, it is a negative electrode active material layer forming region extending on both ends of the central strip region in the width direction.

The mass of the negative electrode active material layer provided per unit area of the negative electrode current collector (the total mass of both surfaces in the structure having the negative electrode active material layer on both sides of the negative electrode current collector) also, for example, (typically ^{5mg / cm 2 ~10mg / cm 2} ) 5mg / cm 2 ~20mg / cm 2 may be of the order. In the configuration having the negative electrode active material layers on both surfaces of the negative electrode current collector, the mass of the negative electrode active material layers provided on each surface of the negative electrode current collector is usually preferably approximately the same. The density of the negative electrode active material layer, for example, (typically ^{1g / cm 3 ~1.5g / cm 3} ) 0.5g / cm 3 ~2g / cm 3 may be of the order.
Then, the thickness and density of the negative electrode active material layer can be adjusted by appropriately pressing the negative electrode. For the press treatment, various known press methods such as a roll press method and a flat plate press method can be employed. The thickness of the negative electrode active material layer after the press treatment is, for example, 20 μm or more (typically 50 μm or more), and can be 200 μm or less (typically 100 μm or less).

<< Step e: Construction of electrode body >>
In step e, an electrode body can be constructed using a negative electrode to which the negative electrode pastes A and B are applied. Typically, a negative electrode and a positive electrode can be overlapped with an insulating material such as a separator to form an electrode body. The negative electrode, the positive electrode, and the separator can increase the battery capacity per unit volume by overlapping a plurality of them, or winding a long one.
<Positive electrode>
The positive electrode of the non-aqueous electrolyte secondary battery disclosed here includes a positive electrode current collector and a positive electrode active material layer including at least a positive electrode active material formed on the positive electrode current collector. A method for producing such a positive electrode is not particularly limited. For example, a positive electrode active material, a conductive material, a binder, and the like are mixed with an appropriate solvent to prepare a positive electrode paste, and the positive electrode paste is applied onto a positive electrode current collector. It can be prepared by forming a positive electrode active material layer. Although the solid content concentration of a positive electrode paste is not specifically limited, For example, it is 10 mass%-60 mass% (preferably 10 mass%-50 mass%) as an example. The method for forming the positive electrode active material layer, the drying method, and the like can be performed in the same manner as in the case of the negative electrode described above.

<Positive electrode current collector>
As the positive electrode current collector, a conductive member made of a metal having good conductivity (for example, aluminum, nickel, titanium, stainless steel, etc.) can be preferably used. The shape of the positive electrode current collector can be the same as the shape of the positive electrode current collector.

<Positive electrode active material>
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 ).

Also, for example, the general formula: xLi [Li _1/3 Mn _2/3 ] O _2. (1-x) LiMeO ₂ , wherein Me is one or more transition metals, and x is 0 It is also possible to use a so-called solid solution type lithium-excess transition metal oxide represented by <satisfying x ≦ 1.

<Conductive material>
As the conductive material, one or more of various substances conventionally used in nonaqueous electrolyte secondary batteries can be used without any particular limitation. For example, carbon black (for example, acetylene black, furnace black, ketjen black, channel black, lamp black, thermal black, etc.), coke, activated carbon, graphite (natural graphite and its modified products, artificial graphite), carbon fiber (PAN) Carbon fiber, pitch-based carbon fiber), carbon nanotube, fullerene, graphene, or other carbon material. Among these, carbon black (typically acetylene black) can be preferably used.

<Solvent>
The solvent is not particularly limited as long as the material used for preparing the positive electrode paste can be uniformly dispersed or dissolved. For example, one or more of the solvents exemplified in the preparation of the negative electrode paste can be used.

<Binder>
As the binder, an appropriate material can be selected and used from the polymer materials exemplified as the binder for preparing the negative electrode paste. Specifically, a binder that can be dissolved or dispersed in a solvent used for preparing the positive electrode paste can be selected and used. Examples of such a binder include styrene butadiene rubber (SBR), polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), and the like.
The polymer material exemplified above for preparing the negative electrode paste may be used as a thickener and other additives for the positive electrode paste in addition to being used as a binder.
In addition, as exemplified in the preparation of the above negative electrode paste, various types of inorganic compounds that can generate gas during overcharge, materials that can function as a dispersant, and the like conventionally added to this type of positive electrode paste Additives can also be used as appropriate.

Although not particularly limited, the mass of the positive electrode active material layer provided per unit area of the positive electrode current collector (the total mass of both surfaces in the configuration having the positive electrode active material layer on both surfaces of the positive electrode current collector) is, for example, 5 mg. / Cm ^{2 to} 40 mg / cm ² (typically 10 mg / cm ^{2 to} 30 mg / cm ² ). In the configuration having the positive electrode active material layers on both surfaces of the positive electrode current collector, the mass of the positive electrode active material layers provided on each surface of the positive electrode current collector is usually preferably approximately the same.

  The proportion of the positive electrode active material in the entire positive electrode active material layer is suitably about 50% by mass or more (typically 50% by mass to 95% by mass), and usually about 70% by mass to 95% by mass. It is preferable that The proportion of the conductive material in the positive electrode active material layer can be, for example, about 0.1 to 20 parts by mass with respect to 100 parts by mass of the positive electrode active material, and is usually about 1 to 15 parts by mass ( For example, it is preferable to set it as 2 mass parts-10 mass parts, typically 3 mass parts-7 mass parts. The proportion of the binder in the positive electrode active material layer can be, for example, approximately 0.5 parts by mass to 10 parts by mass with respect to 100 parts by mass of the positive electrode active material, and is usually approximately 1 part by mass to 5 parts by mass (for example, 2 parts by mass to 7 parts by mass, typically 2 parts by mass to 5 parts by mass).

The thickness and density of the positive electrode active material layer can be adjusted by appropriately pressing the positive electrode. The thickness of the positive electrode active material layer after the press treatment is, for example, 20 μm or more (typically 50 μm or more), and can be 200 μm or less (typically 100 μm or less). The density of the positive electrode active material layer is not particularly limited, but is, for example, 1.5 g / cm ³ or more (typically 2 g / cm ³ or more) and 4.5 g / cm ³ or less (typically 4 .2 g / cm ³ or less). The positive electrode active material layer satisfying the above range can achieve high battery performance (for example, high energy density and output density).

<Separator>
As the separator, various microporous sheets similar to those conventionally used for non-aqueous electrolyte secondary batteries can be used. For example, a porous resin sheet (film, nonwoven fabric, etc.) made of a resin such as polyethylene (PE), polypropylene (PP), polyester, cellulose, polyamide or the like can be mentioned. Such a porous resin sheet may have a single layer structure, or may have a two or more layers structure (for example, a three-layer structure in which a PP layer is laminated on both sides of a PE layer). Moreover, the thing of a structure provided with a porous heat resistant layer in the single side | surface or both surfaces (typically single side | surface), such as the said porous sheet and a nonwoven fabric, may be sufficient. The thickness of the separator is preferably set within a range of about 10 μm to 40 μm, for example.

<Capacitance ratio between positive electrode and negative electrode>
Although not particularly limited, the positive electrode capacity (C _c (mAh)) calculated by the product of the theoretical capacity (mAh / g) per unit mass of the positive electrode active material and the mass (g) of the positive electrode active material. And the negative electrode capacity (C _a (mAh)) calculated by the product of the theoretical capacity per unit mass of the negative electrode active material (mAh / g) and the mass of the negative electrode active material (g) (C _a / C _c ) is usually suitably 1.0 to 2.0, for example, and preferably 1.2 to 1.9 (eg 1.7 to 1.9). The ratio of the positive electrode capacity and the negative electrode capacity facing each other directly affects the battery capacity (or irreversible capacity) and the energy density, and lithium is likely to be precipitated depending on the use conditions of the battery (for example, rapid charging). By setting the capacity ratio of the opposing positive and negative electrodes in the above range, it is possible to favorably suppress lithium deposition while maintaining good battery characteristics such as battery capacity and energy density.

<< Process f: Construction of battery >>
In step f, a battery can be constructed by housing the electrode body prepared above and the non-aqueous electrolyte in a battery case. Typically, after the electrode body is accommodated in the battery case and sealed, a non-aqueous electrolyte is injected from a liquid injection hole or the like provided in the battery case, and the non-aqueous electrolyte solution is sealed by sealing the injection hole. A secondary battery can be obtained.

<Non-aqueous electrolyte>
As the non-aqueous electrolyte, those similar to the non-aqueous electrolyte conventionally used in non-aqueous electrolyte secondary batteries can be used without particular limitation. This nonaqueous electrolytic solution typically has a composition in which a supporting salt is contained in a suitable nonaqueous solvent. Examples of the non-aqueous solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 1,3-dioxolane, and the like. One kind or two or more kinds selected from the group can be used. Examples of the supporting salt include LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) _{3 and the} like. Lithium salts can be used. As an example, a nonaqueous electrolytic solution in which LiPF ₆ is contained at a concentration of about 1 mol / L in a mixed solvent of ethylene carbonate and diethyl carbonate (for example, a volume ratio of 1: 1) can be mentioned.

<Oxalato complex compound>
Moreover, although not an essential component, this nonaqueous electrolytic solution can contain an oxalato complex compound as a film forming agent. As such an oxalato complex compound, one or two or more kinds can be appropriately selected from various compounds that can be used for the preparation of the negative electrode paste A described above. Among these, it is preferable to use a compound represented by the above formula (III), and it is more preferable to use lithium bis (oxalato) borate (LiBOB) represented by the formula (I). By adding such an oxalato complex compound to the non-aqueous electrolyte solution, a film formed by reducing and decomposing the oxalato complex compound on the surface of the positive electrode active material layer and the negative electrode active material layer is formed. Deterioration of substances can be suppressed.
The amount of the oxalato complex compound added to the non-aqueous electrolyte can be appropriately set in consideration of the amount of the external compound added to the negative electrode paste A. For example, it can be appropriately adjusted in the range of about 0.01 mol / L to 0.15 mol / L, preferably in the range of about 0.01 mol / L to 0.1 mol / L.

<Other additives>
Furthermore, although not necessarily required for the non-aqueous electrolyte, an additive such as a gas generating additive may be added, for example, about 0.01 to 10% by mass, as long as the effects of the present invention are not impaired. it can.

<Battery case>
As the battery case, materials and shapes conventionally used for non-aqueous electrolyte secondary batteries can be used. Typical examples of the material of the case include metal materials such as aluminum and steel, and resin materials such as polyphenylene sulfide resin and polyimide resin. Among these, relatively light metals (for example, aluminum and aluminum alloys) can be preferably employed for the purpose of improving heat dissipation and increasing energy density. Further, the shape of the case (outer shape of the container) is not particularly limited. For example, the shape (cylindrical shape, coin shape, button shape), hexahedron shape (cuboid shape, cube shape), bag shape, and the like are processed and deformed. It can be a shape or the like. In addition, the case can be provided with a safety mechanism such as a current interruption mechanism (a mechanism capable of interrupting current in response to an increase in battery temperature and / or internal pressure when the battery is overcharged).

<Distribution of Oxalato Complex Compound Components>
For example, the electrode body can be impregnated with the non-aqueous electrolyte by injecting the non-aqueous electrolyte into the battery case. More specifically, the non-aqueous electrolyte can be impregnated into the positive and negative electrode active material layers and the pores formed in the separator. The impregnation with the nonaqueous electrolytic solution proceeds from the end portions of the stacked positive electrode, negative electrode, and separator toward the inside of the electrode body. Typically, the non-aqueous electrolyte penetrates from the end in the width direction perpendicular to the longitudinal direction of the positive electrode, the negative electrode, and the separator toward the center. Here, as described above, a sodium component is unavoidably present in the electrode body, particularly in the negative electrode active material layer included in the negative electrode, and the sodium component dissolves in the non-aqueous electrolyte and penetrates in the width direction along with its penetration. Thickening towards the center.
Further, the negative electrode active material layer essentially does not contain an oxalato complex compound in the central band region including the center in the width direction orthogonal to the longitudinal direction, but in the region other than the central band region, Complex compounds are included. And although this oxalato complex compound melt | dissolves in a non-aqueous electrolyte and the component (for example, oxalato complex ion) can move to a center strip | belt area | region somewhat, it is roughly negative electrode active material layer area | regions other than this center strip | belt area | region. Can stay on. This can be the same when the oxalato complex compound is contained in the non-aqueous electrolyte.

Since the diffusion rate of sodium ions is generally faster than other ions (which can be oxalate complex ions here), the oxalato complex ions typically migrate to the central zone and then associate with sodium ions, A sparingly soluble oxalato complex salt can be formed in the central strip region. That is, in the negative electrode active material layer in which some of the oxalato complex ions have been transferred after impregnation with the non-aqueous electrolyte solution, the oxalate complex salt that is sparingly soluble in the central band region, and the oxalato complex in the region other than the central band region It is possible to realize a state in which the compound exists evenly. That is, the components of the oxalato complex compound can be distributed uniformly in the penetration direction of the non-aqueous electrolyte in the negative electrode active material layer (that is, the width direction orthogonal to the longitudinal direction).
For example, when lithium bis (oxalato) borate (LiBOB) is arranged as the oxalato complex compound in the negative electrode active material layer region other than the central band region, Na [B (C ₂ O ₄ ) is hardly soluble in the central band region. ₂ ], but the bis (oxalato) borate anion ([B (C ₂ O ₄ ) ₂ ] ⁻ ) is mainly present in the other negative electrode active material layer region, and the [B (C ₂ O ₄ ) ₂ ] component is wide. It can be in a uniformly distributed state in the direction.

≪Process g: Conditioning≫
In the present invention, as step g, conditioning (also referred to as an activation step) is performed in which the battery constructed as described above is charged to a predetermined charging voltage and then discharged to a predetermined discharging voltage. Can be applied. Due to the initial charging treatment such as conditioning, the oxalato complex compound component present on the surface of the negative electrode active material layer is decomposed and derived from the oxalato complex compound applied to the surface of the negative electrode active material layer (which can be the negative electrode active material). A film is formed. When the oxalato complex compound is contained in the nonaqueous electrolytic solution, the oxalato complex compound is similarly decomposed to form a film on the surface of the negative electrode active material layer (which can be the negative electrode active material). Here, as described above, in the negative electrode active material layer before conditioning, since the components of the oxalato complex compound are uniformly distributed, such a film can be formed evenly.
Thereby, the interface between the surface of the negative electrode active material and the non-aqueous electrolyte is stabilized, and the deterioration of the negative electrode active material and further decomposition of the non-aqueous electrolyte components can be prevented. In addition, since the surface resistance of the negative electrode active material layer is uniform, for example, the generation of precipitates derived from charge carriers (for example, metallic lithium in the case of a lithium ion secondary battery) can be suppressed. , Durability is improved.

  Furthermore, in a lithium ion secondary battery using LiBOB, due to uneven formation of a film derived from LiBOB, metal Li is likely to precipitate when the battery is used at a low temperature, resulting in a large decrease in capacity. However, according to the invention disclosed herein, since the uneven formation of the film derived from LiBOB is eliminated as described above, the problem of capacity reduction at low temperatures is also eliminated.

Note that the voltage between the positive and negative terminals (typically the highest voltage reached) in the charging process varies depending on, for example, the electrode material (active material) used, the non-aqueous electrolyte, etc., but at least the potential of the negative electrode is an oxalato complex compound. It is necessary to set it to be lower than the potential (reduction potential (vs. Li ^/ Li ⁺ )) that can be decomposed. On the other hand, if the potential of the positive electrode is too high, the oxidative decomposition reaction of the non-aqueous electrolyte solution is promoted, which may adversely affect the battery performance. Therefore, it is preferable that the voltage between the positive and negative terminals (typically the highest voltage reached) in the charging process is set so as not to greatly exceed the upper limit voltage of the battery. For example, in a battery in which the terminal voltage at 100% SOC is 4.1 V, the charging voltage can be 2 V to 4.5 V (typically 3.5 V to 4.2 V).

When adjusting the voltage, it may be performed by constant current charging (CC charging) from the start of charging until the voltage between the positive and negative terminals reaches a predetermined value, or between the positive and negative terminals from the start of charging. The charging may be performed by constant current constant voltage charging (CCCV charging) in which charging is performed at a constant current until the voltage reaches a predetermined value and charging is performed at a constant voltage for a predetermined time. Usually, the CCCV charging method can be preferably adopted. Thereby, an oxalato complex compound can be decomposed | disassembled suitably and a firm and dense membrane | film | coat can be stably formed on the surface of a negative electrode active material layer. The charge rate at the time of CC charge (it may be at the time of CC charge in a CCCV charge system) is not specifically limited, For example, it shall be about 1 / 50C-5C (1C is the value of the electric current which can be fully charged and discharged in 1 hour). be able to. Usually, it is appropriate to set the charging rate to about 1/30 C to 2 C (for example, 1/20 C to 1 C). If the charge rate is too low, the processing efficiency tends to decrease. On the other hand, if the charging rate is too high, the positive electrode active material may deteriorate, the uniformity of the formed film may decrease, or the reductive degradation prevention performance of the film may tend to decrease.
In addition, the said charge process may be performed once, for example, charging / discharging operation of 2 times or more can also be performed repeatedly. Furthermore, other operations (for example, pressure load due to restraint or irradiation of ultrasonic waves) can be used in combination as long as the battery performance is not greatly affected.

In the non-aqueous electrolyte secondary battery disclosed here, a film derived from the oxalato complex compound is formed on at least a part of the negative electrode active material layer. And the film | membrane derived from this oxalato complex compound is the grade which the film quantity in a center strip | belt area | region becomes in the range of 90-110, when the film quantity in the edge part of the width direction of a negative electrode active material layer is set to 100, for example. It can be homogenized. Such a coating amount can be confirmed by, for example, the concentration of the central element of the oxalato complex compound. That is, the concentration C _A of the central element of the oxalate complex compound is taken as 100, the concentration C _B of the central element of the oxalate complex compound in the central strip-like regions may be in the range of 90 to 110. For reference, for example, in a general negative electrode active material layer not containing oxalate complex compound, C _B when the C _A and 100 can be a more than 110 values (e.g., 114 or more).

  The measurement of the amount of the film, that is, the concentration of the central element of the oxalato complex compound is not particularly limited. For example, a measurement sample is collected from the central band region and the end in the width direction of the negative electrode active material layer of the battery. It can be confirmed by measuring the concentration of the central element in the measurement sample. For example, an inductively coupled plasma (ICP) emission analysis method, an atomic absorption analysis method, an ion chromatography method, or the like can be used for the concentration measurement. More specifically, the negative electrode active material layer taken out by disassembling the battery is washed with an appropriate solvent (for example, EMC), and then a measurement sample having a predetermined weight is collected. Then, the measurement sample is dissolved in an acid solvent, a measurement sample solution is prepared according to the analysis technique, and the content of the target central element in the measurement sample solution is measured.

In the technique disclosed here, LiBOB is preferably used as the oxalato complex compound. In such a case, the content of boron (B) atoms may be obtained in the measurement of the amount of the central element. In addition, when calculating | requiring the film quantity derived from LiBOB, after measuring the boron density | concentration in a sample solution by said analysis, the quantity (for example, unit) of the boron (B) atom per unit weight of a negative electrode active material layer : Μg / mg) and the film weight may be calculated based on the composition of the film. On the other hand, when investigating the distribution state (unevenness) of the film in the width direction perpendicular to the longitudinal direction of the negative electrode active material layer as described above, based on the detection value in the analysis instead of the evaluation based on the accurate concentration Can be evaluated. For example, specifically, instead of the concentration C _A of boron (B) at the end in the width direction orthogonal to the longitudinal direction of the negative electrode active material layer, and the concentration C _B of boron (B) in the central strip region Te, may be employed to detect the intensity I _a and I _B in the analysis of when measuring each.

  Hereinafter, although not intended to be particularly limited, as a schematic configuration of the non-aqueous electrolyte secondary battery according to one embodiment of the present invention, a flatly wound electrode body (winding electrode body) and A non-aqueous electrolyte secondary battery (unit cell) in a form in which a non-aqueous electrolyte is accommodated in a flat rectangular parallelepiped (square) container is shown as an example in FIGS. In the following drawings, members and parts having the same action are denoted by the same reference numerals, and redundant description may be omitted or simplified. Note that the dimensional relationship (length, width, thickness, etc.) in each figure does not reflect the actual dimensional relationship.

  A nonaqueous electrolyte secondary battery 10 according to an embodiment of the technology disclosed herein includes, for example, a battery case 80 having a flat rectangular parallelepiped shape (rectangular shape), as shown in FIGS. The wound electrode body 20 having a shape corresponding to the above-mentioned configuration is accommodated together with a non-aqueous electrolyte solution (not shown). The battery case 80 includes a flat rectangular parallelepiped (rectangular) battery case main body 84 with an open upper end, and a lid 82 that closes the opening. A positive electrode terminal 40 and a negative electrode terminal 60 for external connection are provided on the upper surface (that is, the lid body 82) of the battery case 80 so that a part of the terminals protrudes from the lid body 82 to the outside of the battery 10. Yes. Further, the lid 82 is provided with a safety valve 88 for discharging gas generated inside the battery case 80 to the outside of the case 80. For example, the non-aqueous electrolyte secondary battery 10 having such a configuration is provided in the lid body 82 after the electrode body 20 is accommodated inside the opening portion of the case 80 and the lid body 82 is attached to the opening portion of the case 80. It is constructed by injecting a non-aqueous electrolyte from the prepared electrolyte injection hole 86 and then closing the injection hole 86.

  FIG. 4 is a diagram schematically showing a long sheet structure (electrode sheet) at the stage of assembling the wound electrode body 20. The wound electrode body 20 includes a positive electrode sheet 30 in which a positive electrode active material layer 34 is formed along the longitudinal direction on one or both surfaces (typically both surfaces) of a long positive electrode current collector 32, and a long shape. A negative electrode sheet 50 having a negative electrode active material layer 54 formed in the longitudinal direction on one side or both sides (typically, both sides) of the negative electrode current collector 52 of the negative electrode current collector 52 is overlapped and wound. It is formed into a flat shape by pressing and abating from the side. In the present invention, although the negative electrode active material layer 54 cannot be confirmed by appearance in the assembly stage of the wound electrode body 20, regions 54B that do not contain an oxalato complex compound are formed on both sides of the belt in the center in the width direction. Each of the regions 54A including the oxalato complex compound is formed. And between this positive electrode active material layer 34 and the negative electrode active material layer 54, the insulating layer which prevents both short circuit is arrange | positioned. In the example shown here, when the wound electrode body 20 is produced, a long sheet-like separator 70 is used as the insulating layer. In this example, the width b1 of the negative electrode active material layer 54 is slightly wider than the width a1 of the positive electrode active material layer 34 (b1> a1). Further, the width c1 of the separator 70 is slightly wider than the width b1 of the negative electrode active material layer 54, and c1> b1> a1.

  The positive electrode sheet 30 is formed such that the positive electrode active material layer 34 is not provided (or removed) at one end portion along the longitudinal direction, and the positive electrode current collector 32 is exposed. Similarly, the negative electrode sheet 50 is formed so that the negative electrode active material layer 54 is not provided (or removed) at one end along the longitudinal direction, and the negative electrode current collector 52 is exposed. Yes. A positive current collector 42 is attached to the exposed end of the positive current collector 32, and a negative current collector 62 is attached to the exposed end of the negative current collector 52. The positive terminal 40 and the negative terminal 60 are electrically connected to each other.

  Moreover, according to this invention, the assembled battery which combined multiple nonaqueous electrolyte secondary batteries (unit cell) disclosed here is provided. In an assembled battery in which a plurality of unit cells are connected to each other (typically in series), the overall performance can be influenced by the lowest performance among the unit cells. The non-aqueous electrolyte secondary battery disclosed herein has higher reliability than conventional batteries and is excellent in durability and low-temperature characteristics, and therefore can exhibit higher battery performance as an assembled battery.

Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to the specific examples.
Using lithium bis (oxalato) borate (LiBOB) as the oxalato complex compound, a lithium ion secondary battery was fabricated by the following procedure.

<Sample 1>
(Preparation of negative electrode sheet)
Natural graphite (C) having a particle size of 10 μm as a negative electrode active material, carboxymethylcellulose (CMC) as a thickener, LiBOB as an additive, ion-exchanged water (W) as a solvent, and styrene as a binder A negative electrode paste was prepared using butadiene rubber (SBR).
That is, these materials are first blended in a mass ratio such that CMC: 100 parts by mass, CMC: 1 part by mass, LiBOB: 5 parts by mass, and W: 66 parts by mass, and put into a kneader. After kneading, ion exchange water as a solvent is further added at a ratio of W: 20 parts by mass to adjust the viscosity, and SBR: 1 part by mass (solid content) is added and mixed to contain LiBOB. A negative electrode paste A was prepared.
Further, the above materials are first blended in a mass ratio such that CMC: 100 parts by mass, CMC: 1 part by mass, LiBOB: none, W: 66 parts by mass, and put into a kneader. After kneading, ion-exchanged water as a solvent is further added at a ratio of W: 20 parts by mass to adjust the viscosity, and SBR: 1 part by mass (solid content) is added and mixed, so that the negative electrode paste does not contain LiBOB B was prepared.

As the negative electrode current collector, a copper foil having a thickness of 10 μm was used, and negative electrode active material layer formation regions were set on both surfaces so that the dimension in the width direction perpendicular to the longitudinal direction was 100 mm. Then, a region 6 mm wide in the width direction of the negative electrode active material layer forming region is defined as a central strip region B, and the negative paste B not including LiBOB is added to the central strip region B on both sides of the central strip region. A negative electrode paste A containing LiBOB in each A was applied using a slot die. These negative electrode pastes were applied so that the weight per unit area was 7.6 mg / cm ² (on both sides), dried and pressed to form a negative electrode sheet having a negative electrode active material layer on the negative electrode current collector (thickness 79 μm, An electrode density of 1.1 g / cm ³ ) was produced. After pressing, the electrode plate was processed to 3250 mm to obtain a negative electrode plate.

(Preparation of positive electrode sheet)
LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (LNCM) was used as the positive electrode active material powder, 8 parts by mass of acetylene black (AB) with respect to 100 parts by mass of this positive electrode active material, and polyvinylidene fluoride (PVdF) is blended at a ratio of 2 parts by mass, and kneaded in a kneader while adjusting the viscosity with N-methylpyrrolidone (NMP) as a solvent so that the solid content concentration is 50% by mass. A paste was prepared. As the positive electrode current collector, an aluminum foil having a thickness of 15 μm was used. The positive electrode current collector was applied to both surfaces so as to have a width of 94 mm and a basis weight of 11 mg / cm ² (on both sides) and pressed after drying. A positive electrode sheet (thickness 65 μm, electrode density 2.2 g / cm ³ ) having a positive electrode active material layer thereon was produced. After pressing, the electrode plate was processed to have a length of 3000 mm to obtain a positive electrode plate.

(Construction of non-aqueous electrolyte secondary battery)
The negative electrode sheet and the positive electrode sheet prepared above were wound together with two separator sheets and formed into a flat shape to prepare a wound electrode body. The separator sheet was a three-layer structure in which polypropylene (PP) was laminated on both sides of polyethylene (PE), and had a thickness of 20 μm, a pore diameter of 0.09 μm, and a porosity of 48 volume%. In addition, a positive electrode current collector not coated with a positive electrode active material layer is applied to one end in the winding axis direction of the wound electrode body, and a negative positive electrode active material layer is applied to the other end. The arrangement of each sheet was prepared so that the unprocessed negative electrode current collector was exposed. Then, positive and negative terminals and current collector leads are attached to the lid of the battery case, and these current collector leads are respectively connected to the positive electrode current collector and the negative electrode current collector exposed at the end of the wound electrode body. Welded. The electrode body thus connected to the lid body was accommodated in the battery case from the opening portion, and the opening portion and the lid body were welded. Next, 45 g of non-aqueous electrolyte was injected from the electrolyte injection hole provided in the lid. As a non-aqueous electrolyte, a mixed solvent containing ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a volume ratio of EC: DMC: EMC = 3: 4: 3, A solution obtained by dissolving LiPF ₆ as a supporting salt at a concentration of 1 mol / L and LiBOB as an additive at a concentration of 0.05 mol / L was used.
Thereby, a lithium ion secondary battery (sample 1) having a battery capacity of 4 Ah was constructed.

<Sample 2>
A lithium ion secondary battery (as in sample 1), except that the width of the central strip region B where the negative electrode paste B is applied is 8 mm, and the width of the region A where the negative electrode paste A is applied on both sides is 46 mm. Sample 2) was constructed. The battery capacity of the lithium ion secondary battery of Sample 2 is 4 Ah.
<Sample 3>
A lithium ion secondary battery (as in sample 1), except that the width of the central strip region B to which the negative electrode paste B is applied is 10 mm and the width of the region A to which the negative electrode paste A is applied on both sides is 45 mm. Sample 3) was constructed. The battery capacity of the lithium ion secondary battery of Sample 3 is 4 Ah.
<Sample 4>
A lithium ion secondary battery (as in sample 1), except that the width of the central strip region B where the negative electrode paste B is applied is 12 mm, and the width of the region A where the negative electrode paste A is applied on both sides is 44 mm. Sample 4) was constructed. The battery capacity of the lithium ion secondary battery of Sample 4 is 4 Ah.
<Sample 5>
A lithium ion secondary battery (as in sample 1), except that the width of the central strip region B to which the negative electrode paste B is applied is 14 mm and the width of the region A to which the negative electrode paste A is applied on both sides is 43 mm. Sample 5) was constructed. The battery capacity of the lithium ion secondary battery of Sample 5 is 4 Ah.

<Sample 6>
A lithium ion secondary battery (Sample 6) was constructed in the same manner as Sample 3 except that LiBOB as an additive was not added to the non-aqueous electrolyte. The battery capacity of the lithium ion secondary battery of Sample 6 is 4 Ah.
<Sample 7>
The width of the negative electrode active material layer forming region is set to 120 mm, the width of the central band region B to which the negative electrode paste B is applied is set to 10 mm, and the width of the region A to which the negative electrode paste A is applied on both sides is set to 55 mm. In addition, a lithium ion secondary battery (Sample 7) was constructed in the same manner as Sample 3 except that the width of the positive electrode sheet was increased and the amount of the nonaqueous electrolyte was increased to 51 g. The battery capacity of the lithium ion secondary battery of Sample 7 is 4.8 Ah.
<Sample 8>
The width of the negative electrode active material layer forming region is 140 mm, the width of the central strip region B where the negative electrode paste B is applied is 10 mm, and the width of the region A where the negative electrode paste A is applied on both sides is 65 mm. In addition, a lithium ion secondary battery (Sample 8) was constructed in the same manner as Sample 3 except that the width of the positive electrode sheet was increased and the amount of the non-aqueous electrolyte was changed to 57 g. The battery capacity of the lithium ion secondary battery of Sample 8 is 5.6 Ah.

<Sample 9>
The same as Sample 3 except that the entire negative electrode active material layer forming region was formed with a coating width of 100 mm using only the negative electrode paste B, and the concentration of LiBOB added to the non-aqueous electrolyte was increased to 0.1 mol / L. Thus, a lithium ion secondary battery (Sample 9) was constructed. The battery capacity of the lithium ion secondary battery of Sample 9 is 4 Ah.
<Sample 10>
A lithium ion secondary battery (Sample 10) was constructed in the same manner as Sample 3 except that only the negative electrode paste A was used to form the entire negative electrode active material layer formation region with a coating width of 100 mm. The battery capacity of the lithium ion secondary battery of Sample 10 is 4 Ah.
<Sample 11>
The entire negative electrode active material layer formation region was formed with a coating width of 100 mm using only the negative electrode paste A, and in the same manner as in Sample 3, except that LiBOB as an additive was not added to the nonaqueous electrolytic solution. A lithium ion secondary battery (Sample 11) was constructed. The battery capacity of the lithium ion secondary battery of Sample 11 is 4 Ah.

<Sample 12>
Same as sample 3, except that the amount of LiBOB blended in the negative electrode paste B was reduced to 1 part by mass with respect to 100 parts by mass of the above C: and the concentration of LiBOB added to the non-aqueous electrolyte was reduced to 0.01 mol / L Thus, a lithium ion secondary battery (sample 12) was constructed. The battery capacity of the lithium ion secondary battery of Sample 12 is 4 Ah.
<Sample 13>
A lithium ion secondary battery was prepared in the same manner as in Sample 3, except that the LiBOB amount added to the negative electrode paste B was increased to 10 parts by mass and the concentration of LiBOB added to the non-aqueous electrolyte was increased to 0.1 mol / L. (Sample 13) was constructed. The battery capacity of the lithium ion secondary battery of Sample 13 is 4 Ah.
<Sample 14>
Lithium ion secondary battery was performed in the same manner as Sample 3, except that the LiBOB amount added to the negative electrode paste B was increased to 15 parts by mass and the concentration of LiBOB added to the non-aqueous electrolyte was increased to 0.15 mol / L. (Sample 14) was constructed. The battery capacity of the lithium ion secondary battery of Sample 14 is 4 Ah.

[Evaluation]
(Evaluation of film formation by activation process)
The batteries of Samples 1 to 6 and 9 to 14 constructed as described above were activated according to the following procedure after 6 hours from the injection of the nonaqueous electrolytic solution.
(1) A constant current charge (CC charge) is performed up to 4.1 V at a rate of 4A (1C), and an initial charge is performed.
(2) Store in a constant temperature bath at 60 ° C. for 1 week with the initial charging state.
(3) Constant voltage charging (CV charging) is performed until the current reaches 0.1 A at 4.1 V.
In addition, for the batteries of Samples 7 and 8, in order to make the current amount per unit area equal to that of the other samples, the charge / discharge rates were set to 4.8 A and 5.6 A, respectively, and the above procedures (1) to (3) The activation process was performed.

After the activation step, the batteries of Samples 1 to 14 were disassembled, and the negative electrode near the middle of the outermost periphery and innermost periphery of the negative electrode sheet was cut from the wound electrode body to a length of 100 mm in the longitudinal direction, and EMC 2 to 3 times. Then, as shown in FIG. 5, this negative electrode active material layer is cut into parts (1) to (10) at intervals of 5 mm from the center, and a predetermined amount of the negative electrode active material layer at each part is heated and dissolved in sulfuric acid, By analyzing this solution by ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy) method, the amount (B amount) of boron atoms contained in the measurement sample was measured. And the measured value by ICP is converted into the value per unit weight of the sample used for the measurement, and further, the boron atomic weight in the parts (1) to (3) and the parts (8) to (10) for each battery. When the arithmetic average value of (B amount) is 100, the boron atom amount at each site is shown as a relative value in the “B amount” column of Table 1 below. In Table 1, an underline is provided for the relative value indicating the amount of boron atoms at each site when the relative value exceeds 110 and when the relative value is less than 90.
Note that since the negative electrode active material layer is wider than the positive electrode active material layer, the end portion of the negative electrode active material layer does not contribute to charging and discharging. And from the preliminary test about the negative electrode active material layer similar to the samples 1-14, it is the area | region (namely, said site | part (1)-(3) and site | part (8) about 10 mm-25 mm toward both ends from a center. ) To (10)) and confirm that there is almost no difference between the amount of boron atoms (film amount) and the amount of boron atoms (film amount) at the end in the width direction of the negative electrode active material layer. ing.

(Low temperature cycle test)
For the batteries of Samples 1 to 6 and 9 to 14 constructed above, after the activation process similar to the above after 6 hours from the injection of the non-aqueous electrolyte, the battery was cooled to −15 ° C., A low temperature cycle test was conducted according to the following procedure.
(1) After constant current charging (CC charging) at a rate of 4 A up to 4.1 V, pause for 10 minutes.
(2) After a constant current discharge (CC discharge) at a rate of 4 A up to 3.0 V, rest for 10 minutes.
(3) The above (1) and (2) are regarded as one cycle, and charge / discharge of 10 cycles is performed.
In addition, for the batteries of Samples 7 and 8, in order to make the current amount per unit area equal to that of the other samples, the charge / discharge rates were set to 4.8 A and 5.6 A, respectively, and the above procedures (1) to (3) The activation process was performed.
The battery after the low-temperature cycle test was disassembled, the negative electrode was taken out, and the presence or absence of lithium (Li) precipitation was visually confirmed on the surface of the negative electrode active material layer. The results are shown in the column of “Li precipitation” in Table 1. In addition, the symbol “◯” in the column indicates that no Li precipitation was confirmed, and “x” indicates that Li deposition was confirmed.

  Comparing Samples 1 to 5 in Table 1, as in Samples 2 to 4, by setting the width of the central strip region B to which the negative electrode paste B not including LiBOB is applied to a range of 8 mm to 12 mm, the negative electrode active material layer It was found that a film derived from LiBOB can be formed evenly in the width direction. Li deposition was not observed on the surface of the negative electrode active material layer having no coating unevenness even after a low temperature cycle test.

On the other hand, as in Sample 1, when the width of the central band region B that does not include LiBOB is too narrow and the region A that includes LiBOB extends to the center side, such a region A and a region in which sodium components are unevenly distributed, that is, The region where a large amount of Na [B (C ₂ O4) ₂ ] precipitates overlaps (or the region where the sodium component is unevenly distributed in region B cannot be sufficiently covered), and the width of the negative electrode active material In the direction, unevenness occurs in the component containing bis (oxalato) borate.
Further, as in sample 5, if the central band-like region B not including LiBOB is too wide and the region A including LiBOB is not sufficiently formed, the region A and Na [B (C ₂ O4) ₂ ], A region having a small amount of bis (oxalato) borate component is generated between the region and a region where a large amount of bis (oxalato) borate component is deposited, and the bis (oxalato) borate component is uneven in the width direction of the negative electrode active material.
As a result, it was confirmed that Li was deposited on the surface of the negative electrode active material layer whose resistance was increased by the unevenness of the bis (oxalato) borate component after the low-temperature cycle test. The cause of this Li precipitation is considered to be that the resistance accompanying the insertion and extraction of lithium ions of the negative electrode active material increased as a result of the excessive formation of the film by reducing and decomposing the bis (oxalato) borate component.

  In addition, from the result of sample 6, in the battery including the negative electrode active material layer formed by applying the negative electrode paste A containing LiBOB and the negative electrode paste B not containing LiBOB to an appropriate region, LiBO is particularly added to the non-aqueous electrolyte. It was confirmed that a film derived from LiBOB could be formed evenly in the negative electrode active material layer without addition.

  In addition, from the results of Samples 7 and 8, by setting the width of the central strip region B within the above range of 8 mm to 12 mm, a film derived from LiBOB can be formed uniformly in the width direction of the negative electrode active material layer. all right. That is, since the width of the region B is not affected by the dimension in the width direction of the negative electrode active material layer, it can be confirmed that it can be determined as an absolute value rather than relative to the width of the negative electrode active material layer. It was.

  Sample 9 is a battery including a negative electrode formed only by a negative electrode paste B that does not contain LiBOB that is generally manufactured. In such a battery, when a non-aqueous electrolyte containing LiBOB is injected, the bis (oxalato) borate component is unevenly distributed at the center in the width direction of the negative electrode active material layer along with the impregnation of the electrolyte into the negative electrode active material layer, It was confirmed that many films derived from LiBOB were formed, and Li was deposited in such portions after a cycle test at a low temperature.

  Samples 10 and 11 are batteries each including a negative electrode formed only by the negative electrode paste A containing LiBOB. In such a battery, the bis (oxalato) borate component contained in the negative electrode active material layer dissolves into the electrolyte solution as the nonaqueous electrolyte solution is injected, and moves to the center in the width direction along with the electrolyte solution impregnation. And found that it was unevenly distributed. It has also been found that the movement of the bis (oxalato) borate component becomes significant when LiBOB is not added to the electrolytic solution. In such a battery, it was confirmed that unevenness occurred in the formation of a film derived from LiBOB, and Li was deposited in the unevenness part after a cycle test at a low temperature.

  From the results of Samples 12 to 14, it was found that the blending of LiBOB into the negative electrode paste A has an effect of forming a film derived from LiBOB uniformly on the negative electrode active material layer regardless of the blending amount. However, the blending amount is, for example, about 1 to 10 parts by weight with respect to 100 parts by weight of the negative electrode active material. For example, when 15 parts by weight is blended, the amount of film formed is too large. As a result, it was confirmed that the resistance was increased by the coating derived from LiBOB, leading to precipitation of Li.

  A correlation was found between the distribution of the amount of boron atoms (B amount) in the width direction of the negative electrode active material layer shown in Table 1 and the precipitation of Li. That is, even if there is uneven formation of a coating derived from LiBOB in the negative electrode active material layer, when the boron atom amount (B amount) at the end in the width direction of the negative electrode active material layer is defined as 100, the boron atom amount (B It can be seen that Li precipitation does not occur if the amount is such that the amount is in the range of ± 10%. Further, when the boron atom amount (B amount) at the end in the width direction of the negative electrode active material layer is set to 100, remarkable unevenness such that the boron atom amount (B amount) in the central portion is less than 90 or exceeds 110 is obtained. If it occurs, it can be said that precipitation of Li occurs.

  From the above, according to the manufacturing method disclosed herein, the oxalato complex component can be evenly arranged in the negative electrode active material layer evenly, and the oxalato complex component is decomposed at the time of the first charge so that the negative electrode A battery in which a homogeneous film is formed on the active material can be manufactured. In such a battery, it was shown that the effect of adding LiBOB can be effectively exhibited, and as a result, high battery performance (for example, low temperature characteristics, durability, etc.) can be exhibited.

  As mentioned above, although this invention was demonstrated in detail, the said embodiment and Example are only illustrations and what changed and changed the above-mentioned specific example is contained in the invention disclosed here.

  The battery disclosed here can exhibit the effect of adding an oxalato complex compound suitably, and can exhibit higher battery performance (for example, low temperature characteristics and durability) than conventional ones. Therefore, it can be suitably used in applications requiring high durability and low temperature characteristics. Such applications include, for example, plug-in hybrid vehicles (PHV), hybrid vehicles (HV), electric vehicles (EV), electric trucks, motorbikes, electric assist bicycles, electric wheelchairs, electric railways, and other vehicles. A power source for motors (drive power source) can be mentioned. Therefore, as another aspect of the present invention, a vehicle including any of the nonaqueous electrolyte secondary batteries disclosed herein (preferably as a power source) can be provided. The vehicle may be provided with a plurality of nonaqueous electrolyte secondary batteries, typically in the form of an assembled battery in which they are connected in parallel.

10 non-aqueous electrolyte secondary battery 20 wound electrode body 30 positive electrode sheet (positive electrode)
32 Positive electrode current collector 34 Positive electrode active material layer 40 Positive electrode terminal 42 Positive electrode current collector plate 50 Negative electrode sheet (negative electrode)
52 Negative electrode current collector 54 Negative electrode active material layer 60 Negative electrode terminal 62 Negative electrode current collector plate 70 Separator sheet (separator)
80 Battery Case 82 Lid 84 Case Body 86 Injection Hole 88 Safety Valve

Claims (10)

A step of preparing a negative electrode paste A by kneading a negative electrode active material and an oxalato complex compound with a predetermined solvent;
A step of preparing a negative electrode paste B by kneading a negative electrode active material with a predetermined solvent without containing an oxalato complex compound;
The negative electrode paste B is applied to a central band-shaped region that is a negative electrode active material layer forming region on a long negative electrode current collector and includes a center in the width direction perpendicular to the longitudinal direction of the negative electrode active material layer forming region. Process,
Applying the negative electrode paste A to the negative electrode active material layer forming region excluding the central band region;
A step of constructing an electrode body using a negative electrode to which the negative electrode pastes A and B are applied, and
A step of building a battery by housing the electrode body and a non-aqueous electrolyte in a battery case;
A method for producing a non-aqueous electrolyte secondary battery.   The manufacturing method according to claim 1, wherein a width of the central belt-shaped region is 8 mm or more and 12 mm or less.   The said negative electrode paste A is a manufacturing method of Claim 1 or 2 which contains an oxalato complex compound in the ratio of 1-10 mass parts with respect to 100 mass parts of negative electrode active materials.   The manufacturing method according to any one of claims 1 to 3, wherein at least one of the negative electrode paste A and the negative electrode paste B contains a thickener.   The manufacturing method of any one of Claims 1-4 which adds the said oxalato complex compound to the said non-aqueous electrolyte.   The manufacturing method according to any one of claims 1 to 5, wherein lithium bis (oxalato) borate is used as the oxalato complex compound. Furthermore, after charging the battery constructed to a predetermined charging voltage, including a step of conditioning to discharge to a predetermined discharge voltage,
In the battery having been subjected to the conditioning, central element of the said is 100 concentration C _A of the central element of the oxalate complex compound in an edge in the width direction of the negative electrode active material layer, the in the central strip region oxalate complex compound configuring such that the concentration _{C B} is in the range of 90 to 110 a process according to any one of claims 1-6.   The manufacturing method of any one of Claims 1-7 using graphite as the said negative electrode active material. An electrode body formed by laminating a long positive electrode having a positive electrode active material layer containing a positive electrode active material and a negative electrode having a long negative electrode active material layer containing a negative electrode active material via a separator is non-aqueous electrolysis. A non-aqueous electrolyte secondary battery housed in a battery case together with a liquid,
The negative electrode active material layer includes a film derived from an oxalato complex compound at least in part,
Wherein when the oxalato 100 concentration C _A of the central element of the complex compound in an edge in the width direction perpendicular to the longitudinal direction of the negative electrode active material layer, the center in the width direction orthogonal to the longitudinal direction of the negative electrode active material layer the concentration C _B of the central element of the oxalate complex compound is within a range of 90 to 110, a non-aqueous electrolyte secondary battery in the central strip region including.   The nonaqueous electrolyte secondary battery manufactured by the method of any one of Claims 1-8.

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