JP6984202B2 - A control device and a control method for a non-aqueous electrolyte secondary battery, a non-aqueous electrolyte secondary battery system having the control device, and a method for manufacturing a non-aqueous electrolyte secondary battery. - Google Patents

Description

The present invention relates to a control device and a control method for a non-aqueous electrolyte secondary battery, a non-aqueous electrolyte secondary battery system having the control device, and a method for manufacturing a non-aqueous electrolyte secondary battery. The non-aqueous electrolyte secondary battery according to the present invention is used, for example, as a driving power source or an auxiliary power source for a motor of a vehicle such as an electric vehicle, a fuel cell vehicle, or a hybrid electric vehicle.

In recent years, in order to cope with global warming, it is urgently desired to reduce the amount of carbon dioxide. In the automobile industry, expectations are high for the reduction of carbon dioxide emissions through the introduction of electric vehicles (EVs) and hybrid electric vehicles (HEVs), and electric devices such as secondary batteries for driving motors that hold the key to their practical application. Is being actively developed.

The secondary battery for driving a motor is required to have extremely high output characteristics and high energy as compared with a consumer lithium ion secondary battery used in mobile phones, notebook computers and the like. Therefore, lithium-ion secondary batteries, which have the highest theoretical energy among all batteries, are attracting attention and are currently being rapidly developed.

Lithium-ion secondary batteries generally include a positive electrode in which a positive electrode active material or the like is applied to both sides of a positive electrode current collector using a binder, and a negative electrode in which a negative electrode active material or the like is applied to both sides of a negative electrode current collector using a binder. However, it has a configuration in which it is connected via an electrolyte layer and is housed in a battery case.

Conventionally, a carbon / graphite-based material, which is advantageous in terms of charge / discharge cycle life and cost, has been used for the negative electrode of a lithium ion secondary battery. However, since carbon / graphite-based negative electrode materials are charged / discharged by occluding / discharging lithium ions into graphite crystals, _{the charging / discharging capacity obtained from LiC 6} , which is the maximum lithium-introduced compound, has a theoretical capacity of 372 mAh / g or more. Has the drawback of not being obtained. Therefore, it is difficult to obtain a capacity and energy density satisfying the practical level for vehicle applications with carbon / graphite negative electrode materials.

On the other hand, _{a battery using a silicon-containing negative electrode active material such as a SiO x} (0 <x <2) material forming a compound with Li or an alloy-based material containing silicon is a conventional carbon / graphite-based negative electrode material. Since the energy density is improved as compared with that of the above, it is expected as a negative electrode material in vehicle applications. For example, in the _{silicon oxide having a chemical composition represented by SiO x} , Si (single crystal nanoparticles) and amorphous SiO ₂ are phase-separated from each other when viewed microscopically.

On the other hand, as an effort to increase the energy density of the positive electrode material, the layered compound xLi ₂ MnO _3- (1-x) LiMe'O ₂ (Me'in the formula represents Co, Mn, Ni, Cr, etc.). ) Has been attempted to be used as a positive electrode active material. In this solid solution positive electrode active material, a part of Li is replaced with a transition metal, and Li has an excessive crystal structure. Then, when the solid solution positive electrode active material is charged with a high voltage, _{activation due to reorganization of the crystal structure (change from a layered structure (Li 2} MnO ₃ ) to a spinel structure (LiMn ₂ O ₄ )) occurs. High capacity can be achieved.

However, in such a solid solution positive electrode active material, oxygen gas is released due to a change in the crystal structure during charging, and the battery swells due to the oxygen gas when actually used as the positive electrode active material of the lithium ion secondary battery. It's a problem. Further, when oxygen gas is generated, there is a problem that sufficient charge / discharge characteristics cannot be exhibited.

A technique described in Patent Document 1 has been proposed for such a problem. Specifically, the technique described in Patent Document 1 is xLi ₂ MnO _3- (1-x) LiMn _a Co _b Ni _c O ₂ (in the formula, 0.2 ≦ x ≦ 0.5, 0.3 ≦ a). ≦ 0.5, 0.1 ≦ b ≦ 0.3, 0.3 ≦ c ≦ 0.5, a + b + c = 1) At least a part of the surface of the solid solution is other than Mn, Co and Ni. It is coated with an oxide or an oxide lithium salt of the transition metal of. As a result, it is said that a high-capacity solid solution positive electrode active material in which the generation of oxygen gas during charging is suppressed is provided.

Japanese Unexamined Patent Publication No. 2012-129166

In a battery having a small capacity, it is possible to suppress a decrease in the discharge capacity by alleviating the influence of the generation of oxygen gas at the time of charging by the technique described in Patent Document 1. However, as a result of further studies by the present inventors, for example, in a high-capacity and high-density (battery volume per battery capacity) battery that can be used as a driving power source for an electric vehicle or the like, oxygen is supplied during charging. It was found that when gas is generated, the discharge capacity decreases (cycle durability decreases) as the number of cycles increases.

Therefore, an object of the present invention is to provide a means capable of suppressing a decrease in cycle durability of a high-capacity and high-density non-aqueous electrolyte secondary battery using a solid solution positive electrode active material and a silicon-containing negative electrode active material.

In one embodiment of the present invention, an activation treatment (containing a solid solution positive electrode active material to be activated) for producing a high-capacity and high-density non-aqueous electrolyte secondary battery using a solid solution positive electrode active material and a silicon-containing negative electrode active material. In the process of reorganizing the crystal structure by performing a charge process on the power generation element), the value of the charge state of the power generation element is set in advance from the relationship between the charge state of the power generation element and the amount of gas generated. The above problem is solved by controlling the charging process so as not to exceed the upper limit of the state.

Further, in another embodiment of the present invention, when a high-capacity and high-density non-aqueous electrolyte secondary battery using a solid solution positive electrode active material and a silicon-containing negative electrode active material is used, the value of the charged state of the power generation element is determined. The above problem is solved by controlling the charge / discharge of the power generation element so as not to exceed the upper limit value of the charge state set in advance from the relationship between the charge state of the power generation element and the amount of gas generated.

In the present invention, a high-capacity and high-density non-aqueous electrolyte secondary battery using a solid-solution positive electrode active material and a silicon-containing negative electrode active material is manufactured or manufactured by controlling the state of charge so that the amount of gas generated is small. use. Therefore, it is possible to prevent a decrease in capacity and an imbalance in the A / C ratio due to oxidation of the negative electrode due to gas generation, and it is possible to suppress a decrease in cycle durability of the battery.

A flat (non-bipolar) non-aqueous electrolyte secondary battery, which is an example of a non-aqueous electrolyte secondary battery manufactured by the manufacturing method according to the present invention and controlled by the control method and the control device according to the present invention. It is a plan view which shows. It is sectional drawing which follows the IIA-IIA line of FIG. It is sectional drawing which follows the IIB-IIB line of FIG. FIG. 3 is a block diagram showing a configuration including a control device for carrying out an activation treatment, among the methods for manufacturing a non-aqueous electrolyte secondary battery according to an embodiment of the present invention. Relationship between the charge state (positive electrode capacity), which is the basis for setting the upper limit value of the charge state stored in the control device (particularly the storage unit) of FIG. 3A, the positive electrode potential (●), and the amount of oxygen gas generated (○). It is a figure which shows an example. It is a block diagram which shows the electric vehicle equipped with the non-aqueous electrolyte secondary battery which concerns on one Embodiment of this invention. 3 is a graph plotting the discharge capacity in each cycle of the cycle durability test for Example 3 and Comparative Example 3. "The value of the ratio of the battery volume (the product of the projected area of the battery including the battery exterior and the thickness of the battery) to the rated capacity of the battery is 10 cm ³ / Ah or less, and the rated capacity is 3 Ah or more. It is a graph which plotted the discharge capacity in each cycle of the cycle durability test when the same comparative experiment (cycle durability test) as shown in FIG. 5A was performed using the battery which is not "battery".

Hereinafter, embodiments for carrying out the present invention will be described in detail, but the present invention is not limited to the following embodiments. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.

The present invention comprises a positive electrode containing an activated solid solution positive electrode active material, a negative electrode containing a silicon-containing negative electrode active material, and an electrolyte layer containing a non-aqueous electrolyte interposed between the positive electrode and the negative electrode. The present invention relates to a method for manufacturing a non-aqueous electrolyte secondary battery having a power generation element, and a control method and a control device.

<< Configuration example of non-aqueous electrolyte secondary battery >>
FIG. 1 is a flat (non-bipolar) non-aqueous electrolyte which is an example of a non-aqueous electrolyte secondary battery manufactured by the production method according to the present invention and controlled by the control method and the control device according to the present invention. It is a top view which shows the secondary battery (hereinafter, also simply referred to as a "stacked battery"). FIG. 2A is a cross-sectional view taken along the line IIA-IIA of FIG. FIG. 2B is a cross-sectional view taken along the line IIB-IIB of FIG. Examples of the non-aqueous electrolyte secondary battery (laminated battery) 10 include a lithium-based secondary battery such as a lithium-ion secondary battery. However, the non-aqueous electrolyte secondary battery shown below is an example of a non-aqueous electrolyte secondary battery manufactured by the manufacturing method according to the present invention and to be controlled by the control method and the control device according to the present invention. Non-aqueous electrolyte secondary batteries having structures other than the above are also included in the technical scope of the present invention.

As shown in FIG. 1, the laminated battery 10 of the present embodiment has a structure in which a substantially rectangular power generation element 21 in which a charge / discharge reaction actually proceeds is sealed inside a battery outer body 29 which is an outer body. Have. Here, the power generation element 21 has a configuration in which a positive electrode, an electrolyte layer 17, and a negative electrode are laminated. The positive electrode has a structure in which the positive electrode active material layers 15 are arranged on both sides of the positive electrode current collector 12. The negative electrode has a structure in which the negative electrode active material layers 13 are arranged on both sides of the negative electrode current collector 11. Specifically, the negative electrode, the electrolyte layer, and the positive electrode are laminated in this order so that one positive electrode active material layer 15 and the negative electrode active material layer 13 adjacent thereto face each other via the electrolyte layer 17. .. As a result, the adjacent positive electrode, electrolyte layer and negative electrode form one cell cell layer 19. Therefore, it can be said that the laminated battery 10 shown in FIG. 1 has a configuration in which a plurality of single battery layers 19 are stacked and electrically connected in parallel.

Although the negative electrode active material layer 13 is arranged on only one side of each of the outermost layer negative electrode current collectors located in both outermost layers of the power generation element 21, active material layers may be provided on both sides. That is, instead of using a current collector dedicated to the outermost layer having an active material layer on only one side, a current collector having active material layers on both sides may be used as it is as a current collector for the outermost layer. Further, by reversing the arrangement of the positive electrode and the negative electrode as in FIG. 1, the outermost layer positive electrode current collectors are located on both outermost layers of the power generation element 21, and the outermost layer positive electrode current collectors are located on one side or both sides of the outermost layer positive electrode current collectors. The positive electrode active material layer may be arranged.

A positive electrode current collector plate 27 and a negative electrode current collector plate 25 that are conductive to each electrode (positive electrode and negative electrode) are attached to the positive electrode current collector 12 and the negative electrode current collector 11, respectively, and are sandwiched between the ends of the battery exterior 29. It has a structure that is led out to the outside of the battery exterior body 29. The positive electrode current collector plate 27 and the negative electrode current collector plate 25 are ultrasonically welded to the positive electrode current collector 12 and the negative electrode current collector 11 of each electrode via positive electrode leads and negative electrode leads (not shown), respectively, as necessary. It may be attached by resistance welding or the like.

Further, as shown in FIG. 2B, the laminated battery 10 of the present embodiment is provided with a reference electrode (lithium metal reference electrode) 31. The reference electrode 31 is for detecting the potential of the positive electrode of the laminated battery 10 with respect to the potential of the reference electrode 31, and the lithium ion is connected to the positive electrode active material layer 15 (or the negative electrode active material layer 13). Movement can take place. In other words, it is necessary that the ionic conductivity between the positive electrode and the negative electrode is ensured. Therefore, the reference electrode 31 of the present embodiment is sandwiched between the positive electrode active material layer 15 and the negative electrode active material layer 13, and an electrolyte layer in which lithium ions are transferred during charging / discharging (in the separator 17 in the present embodiment). It is provided in. A reference electrode lead 33 is connected to the reference electrode 31, and is further taken out as a reference electrode tab 35 to the outside of the laminated battery 10 (specifically, the battery exterior 29).

[Positive electrode active material layer]
The positive electrode active material layer contains a positive electrode active material that can occlude ions such as lithium ions at the time of discharge and release ions such as lithium ions at the time of charging. Here, as described above, the non-aqueous electrolyte secondary battery according to the present invention is a so-called high-capacity and high-density battery. In order to form such a high-capacity battery, the positive electrode active material layer of the present embodiment contains an activated solid solution positive electrode active material. _{The solid solution positive electrode active material has a layered structure portion and a portion (Li 2} MnO ₃ having a layered structure) that changes to a spinel structure by being charged or charged / discharged in a predetermined potential range. Here, the specific composition of the solid solution positive electrode active material is not particularly limited, but it is preferably composed of a solid solution lithium-containing transition metal oxide. Further, the solid solution positive electrode active material is more preferably the following chemical formula (1) :.
Li [Ni _a Co _b Mn _c [Li] _d ] O _z ... (1)
In the formula, Li is lithium, Ni is nickel, Co is cobalt, Mn is manganese, O is oxygen, z is the number of oxygen satisfying the atomic value, and a, b, c and d are 0 <a <. Satisfy the relationship of 0.94, 0 ≦ b <0.94, 0 <c <0.94, 0.05 ≦ d ≦ 0.8, a + b + c = 1.
It is preferable that the solid solution lithium-containing transition metal oxide having the composition represented by is provided as a basic structure.

When such a solid solution positive electrode active material (preferably a solid solution lithium-containing transition metal oxide) is used as the positive electrode active material of a lithium ion secondary battery, it becomes possible to realize a high discharge capacity and a capacity retention rate. In particular, a very high discharge capacity can be realized by changing _{Li 2} Mn O _{3 having a layered structure to Li Mn 2 O 4} having a spinel structure in the solid solution positive electrode active material by an activation treatment described later. As a result, it can be suitably used as a lithium ion secondary battery for a vehicle drive power source or an auxiliary power source. In addition, it is fully applicable to lithium-ion secondary batteries for home and mobile devices.

In formula (1), Li is lithium, Ni is nickel, Co is cobalt, Mn is manganese, O is oxygen, z is the number of oxygen satisfying the atomic value, and a, b, c and d are 0. It satisfies the relationship of <a <0.94, 0 ≦ b <0.94, 0 <c <0.94, 0.05 ≦ d ≦ 0.8, a + b + c = 1. This has the advantage that the structure of the solid solution is sufficiently stable. The oxygen number represented by z is "satisfying the valence", and the oxygen number z "satisfying the valence" is a solid solution lithium-containing transition having a composition represented by the chemical formula (1). When the metal oxide is _{a solid solution containing Li 2} MnO ₃ and LiMe'O _{2 in} a molar ratio of x: 1-x (x is 0 <x <1), a value satisfying z = 2 + x. It is possible to ask for. Further, in this case, d = x.

In the solid solution lithium-containing transition metal oxide of the present embodiment, in the composition formula (1), a, b and c are 0 <a <0.9, 0 ≦ b <0.9, 0 <c <0. It is preferable that the relationship of .9 is satisfied, and more preferably that the relationship of 0 <a <0.87, 0 ≦ b <0.87, 0 <c <0.87 is satisfied. Further, the solid solution lithium-containing transition metal oxide of the present embodiment has a composition formula (1) as a composition that can secure an advantage from the viewpoint of energy density even if the upper limit value of the state of charge of the power generation element in the activation treatment is set. In, d preferably satisfies the relationship of 0.1 ≦ d ≦ 0.8, more preferably satisfies the relationship of 0.2 ≦ d ≦ 0.7, and 0. It is more preferable that the relationship of 2 ≦ d ≦ 0.6 is satisfied. In other words, the lithium composition (represented by 1 + d) in the above-mentioned composition formula (1) is preferably 1.1 to 1.8, more preferably 1.2 to 1.7, and even more preferably. 1.2 to 1.6.

The above-mentioned solid solution positive electrode active material may be used as the positive electrode active material itself, or the solid solution positive electrode active material has a solid solution lithium-containing transition having a composition represented by the solid solution positive electrode active material (preferably the chemical formula (1)). It may be appropriately modified and used to the extent that it can be confirmed that it is derived from (metal oxide). Here, as the modified form of the solid solution positive electrode active material, for example, the following three forms (A) to (C) are exemplified.

(A) Al, Zr, Ti, Nb, B, S, Sn, on the particle surface of the above-mentioned solid solution positive electrode active material (preferably a solid solution lithium-containing transition metal oxide having a composition represented by the chemical formula (1)). The form in which one or more elements M selected from the group consisting of W, Mo and V are present (at this time, the abundance of the element M (atomic composition molar ratio when a + b + c = 1)) is [. It is preferable that the amount exists in an amount satisfying 0.002 ≦ [M] / [a + b + c] ≦ 0.05 when M] is set);
(B) A form in which a coating layer made of a metal oxide or a composite oxide selected from the group consisting of Al, Zr and Ti is formed on the particle surface of the above-mentioned solid solution positive electrode active material (at this time, after coating). The content of the oxide or composite oxide in the solid solution positive electrode active material is preferably 0.1 to 3.0% by weight in terms of oxide);
(C) A form in which the Mn atom contained in the above-mentioned solid solution positive electrode active material is substituted with at least one selected from the group consisting of Ti, Zr and Nb.

Further, the positive electrode active material layer may further contain a positive electrode active material other than the above-mentioned predetermined solid solution positive electrode active material. Examples of such positive electrode active materials are preferably composite oxides of lithium and transition metals, transition metal oxides, transition metal sulfides, PbO ₂ , AgO, NiOOH and the like, which may be used alone or 2 It can also be used by mixing more than seeds.

Examples of composite oxide of the lithium and a transition _metal, LiMnO 2, LiMn based composite oxides such as _{LiMn 2 O 4, Li 2 MnO} 3, Li-Co based composite oxide such as LiCoO _2, LiNiO _2. Li-Ni-based composite oxides such as Li (Ni-Co-Mn) O ₂ , Li-Fe-based composite oxides such as _{LiFeO 2} , composite phosphate compounds of lithium and transition metals such as _{LiFePO 4, or} A composite sulfate compound of lithium and a transition metal is preferable. Examples of the transition metal _oxides, such as _{V 2 O 5, MnO 2,} V 2 MoO 8 or MoO _3, are preferably exemplified. As an example of the transition metal sulfide, TiS ₂ or MoS ₂ is preferably mentioned. These positive electrode active materials can be used alone or in combination of two or more.

The positive electrode active material layer includes the above-mentioned optional components (surfactant, conductive auxiliary agent, binder, electrolyte (polymer matrix, ionic conductive polymer, electrolytic solution, etc.), lithium salt for enhancing ionic conductivity, etc.) depending on the purpose. ) Can be included.

The binder of the optional component used for the positive electrode active material layer is not particularly limited as long as it is hydrophobic, and examples thereof include the following materials.

Polybutylene terephthalate, polyethylene terephthalate, polyvinylidene fluoride (PVDF) (including compounds in which hydrogen atoms are replaced with other halogen elements), polyethylene, polypropylene, polymethylpentene, polybutene, polyethernitrile, polytetrafluoroethylene, Polyacrylonitrile, polyimide, polyamide, ethylene-vinyl acetate copolymer, polyvinyl chloride, styrene / butadiene rubber (SBR), ethylene / propylene / diene copolymer, styrene / butadiene / styrene block copolymer and its hydrogen additive , Thermoplastic polymers such as styrene / isoprene / styrene block copolymers and their hydrogenated additives, tetrafluoroethylene / hexafluoropropylene copolymers (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymers (PFA). , Fluororesin such as ethylene / tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene / chlorotrifluoroethylene copolymer (ECTFE), polyvinylfluorovinyl (PVF), vinylidene fluoride- Hexafluoropropylene-based fluororubber (VDF-HFP-based fluororubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-based fluororubber (VDF-HFP-TFE-based fluororubber), vinylidene fluoride-pentafluoropropylene-based fluororubber (VDF-PFP-based fluororubber), vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene-based fluororubber (VDF-PFP-TFE-based fluororubber), vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene-based fluororubber (VDF-PFP-TFE-based fluororubber) Examples thereof include vinylidene fluoride-based fluororubbers such as VDF-PFMVE-TFE-based fluororubber) and vinylidene fluoride-chlorotrifluoroethylene-based fluororubber (VDF-CTFE-based fluororubber), and epoxy resins. Of these, polyimide, styrene-butadiene rubber, carboxymethyl cellulose, polypropylene, polytetrafluoroethylene, polyacrylonitrile, and polyamide are more preferable.

These suitable binders have excellent heat resistance, have a very wide potential window and are stable at the positive electrode potential, and can be used as an active material layer. These binders may be used alone or in combination of two or more. As these binders, those dissolved in an organic solvent in which the binder is soluble, such as N-methyl-2-pyrrolidone (NMP), can also be used in the manufacturing process.

As the surfactant, known cationic surfactants, anionic surfactants, and amphoteric surfactants can be used.

The conductive additive refers to an additive compounded to improve the conductivity of the active material layer. Examples of the conductive auxiliary agent include carbon black such as acetylene black and carbon materials such as carbon fiber. When the positive electrode active material layer contains a conductive auxiliary agent, an electronic network inside the positive electrode active material layer is effectively formed, which can contribute to the improvement of the output characteristics of the battery.

As the electrolyte, an electrolyte salt (lithium salt) is preferable, and specific examples thereof include Li (C ₂ F ₅ SO ₂ ) ₂ N, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO _{3 and the} like. Be done.

Examples of the ionic conductive polymer include polyethylene oxide (PEO) -based and polypropylene oxide (PPO) -based polymers.

Further, in the present invention, other additives such as a conductive auxiliary agent, an electrolyte (polymer matrix, ionic conductive polymer, electrolytic solution, etc.) and a lithium salt for enhancing ionic conductivity, which may be contained in the positive electrode active material layer, are used. The compounding ratio is not particularly limited. Their compounding ratio can be adjusted by appropriately referring to known knowledge about non-aqueous electrolyte secondary batteries.

[Negative electrode active material layer]
The negative electrode active material layer contains a negative electrode active material that can emit ions such as lithium ions at the time of discharge and occlude ions such as lithium ions at the time of charging. Here, as described above, the non-aqueous electrolyte secondary battery according to the present invention is a so-called high-capacity and high-density battery. In order to form such a high-capacity battery, the negative electrode active material layer of the present embodiment indispensably contains a silicon-containing negative electrode active material. The specific form of such a silicon-containing negative electrode active material is not particularly limited, but it is particularly preferable that SiOx or a silicon-containing alloy (collectively referred to as “Si material”) is essentially contained. From the viewpoint of being able to form a high-capacity negative electrode, it is more preferable to include a silicon-containing alloy indispensably. Moreover, in another preferable embodiment, it is more preferable to include the Si material together with the carbon material, and it is further preferable to include the silicon-containing alloy together with the carbon material. Hereinafter, the Si material, which is a preferable silicon-containing negative electrode active material, and the carbon material, which is preferably used in combination, will be described in more detail.

In the present specification, the Si material means SiOx (x represents an oxygen number satisfying the valence of Si) which is a mixture of _{amorphous SiO 2 particles and Si particles, and a silicon-containing alloy.} Only one of these may be used as the Si material, or two or more may be used in combination. Hereinafter, these Si materials will be described in detail.

(SiOx)
SiOx is _{a mixture of two} amorphous SiO particles and Si particles, and x represents the number of oxygens satisfying the valence of Si. There is no particular limitation on the specific value of x, and it can be set as appropriate.

Further, the SiOx may be conductive SiOx particles in which the surface of the SiOx particles is coated with a conductive substance by a mechanical surface fusion treatment. With such a configuration, Si in the SiOx particles can easily desorb and insert lithium ions, and the reaction in the active material can proceed more smoothly. In this case, the content of the conductive substance in the conductive SiOx particles is preferably 1 to 30% by weight, more preferably 2 to 20% by weight.

The average particle size of the SiOx may be about the same as the average particle size of the negative electrode active material contained in the existing negative electrode active material layer 13, and is not particularly limited. From the viewpoint of increasing the output, it may be preferably in the range of 1 to 20 μm. However, it is needless to say that the range is not limited to the above range and may be out of the above range as long as the effects of the present embodiment can be effectively exhibited. In the present specification, the "average particle diameter" refers to the volume-based median diameter (D50) obtained by the laser diffraction method. The shape of SiOx is not particularly limited and may be spherical, elliptical, columnar, polygonal, scaly, amorphous or the like.

The value of x can be obtained by fluorescent X-ray analysis. For example, it can be obtained by using the fundamental parameter method in fluorescent X-ray analysis using OKα rays. For fluorescent X-ray analysis, for example, RIX3000 manufactured by Rigaku Co., Ltd. can be used. As the conditions for fluorescent X-ray analysis, for example, rhodium (Rh) may be used as the target, the tube voltage may be 50 kV, and the tube current may be 50 mA. The x value obtained here is an average value of the measurement area because it is calculated from the intensity of the OKα ray detected in the measurement area on the substrate.

(Silicon-containing alloy)
The silicon-containing alloy is not particularly limited as long as it is an alloy with another metal containing silicon, and conventionally known findings can be appropriately referred to. Here, as preferred embodiments of the silicon-containing alloy, Si _x T _y G _z A _a , S _x T _{y Z z} A _a , Si _x T _y Sn _z A _a , Si _x Sn _y Al _z A _a , Si _x Sn _y V _z A _a , Si _x Sn _y C _z A _a , Si _x Zn _y V _z A _a , Si _x Zn _y Sn _z A _a , Si _x Zn _y Al _z A _a , Si _x Zn _y C _z A _a , Si _x Al _y C _z A _a and Si _x Al _y Nb _z A _a (A is an unavoidable impurity in the formula. Further, x, y, z, and a represent values of% by weight. 0 <x <100, 0 <y <100, 0 <z <100, and 0 ≦ a <0.5, and x + y + z + a = 100). By using these silicon-containing alloys as the negative electrode active material, the phase transition of amorphous-crystal is suppressed during Li alloying by appropriately selecting the predetermined first additive element and the predetermined second additive element. The cycle life can be improved. Further, this makes the capacity of the conventional negative electrode active material higher than that of the conventional negative electrode active material, for example, a carbon-based negative electrode active material.

(Carbon material)
The carbon material that can be used in the present invention is not particularly limited, but is graphite (graphite) which is a highly crystalline carbon such as natural graphite and artificial graphite; low crystalline carbon such as soft carbon and hard carbon; Carbon blacks such as acetylene black, channel black, lamp black, oil furnace black, and thermal black; carbon materials such as fullerene, carbon nanotubes, carbon nanofibers, carbon nanohorns, and carbon fibrils can be mentioned. Of these, it is preferable to use graphite. The shape of the carbon material is not particularly limited and may be spherical, elliptical, columnar, polygonal, scaly, amorphous or the like.

The average particle size of the carbon material is not particularly limited, but is preferably 5 to 25 μm, more preferably 5 to 10 μm. At this time, regarding the ratio of the above-mentioned average particle size to SiOx, the average particle size of the carbon material may be the same as or different from the average particle size of SiOx, but it is preferable that the average particle size is different. In particular, it is more preferable that the average particle size of the SiOx is smaller than the average particle size of the carbon material. When the average particle size of the carbon material is relatively larger than the average particle size of SiOx, the particles of the carbon material are uniformly arranged, and SiOx is arranged between the particles of the carbon material. Therefore, the negative electrode active material layer. SiOx can be uniformly arranged in the room.

The ratio of the particle size to the average particle size of the carbon material and the average particle size of SiOx (average particle size of SiOx / average particle size of the carbon material) is preferably less than 1/250 to 1,100 to 1/100. It is more preferably 1/4.

In the present embodiment, the silicon-containing negative electrode active material is used as the negative electrode active material, preferably the Si material is used, and more preferably the silicon-containing alloy is used, so that the cycle durability is higher. It is possible to show well-balanced characteristics with high initial capacity while showing the properties. Further, these characteristics can also be improved by using these silicon-containing negative electrode active materials in combination with a carbon material.

In some cases, a negative electrode active material other than the silicon-containing negative electrode active material described above may be used in combination. Examples of the negative electrode active material that can be used in combination include a lithium-transition metal composite oxide (for example, Li ₄ Ti ₅ O ₁₂ ), a metal material, and a lithium alloy-based negative electrode material. Of course, other negative electrode active materials may be used.

The negative electrode active material layer contains the above-mentioned predetermined negative electrode active material, and if necessary, to enhance a surfactant, a conductive auxiliary agent, a binder, an electrolyte (polymer matrix, an ionic conductive polymer, an electrolytic solution, etc.), and ionic conductivity. Further contains other additives such as the lithium salt of. For other additives such as surfactants, conductive auxiliaries, binders, electrolytes (polymer matrix, ionic conductive polymers, electrolytes, etc.), lithium salts to enhance ionic conductivity, see the above Positive Active Material Layer column. It is the same as the one described in.

[Electrolyte layer]
The electrolyte layer is a layer containing an electrolyte, and usually has a structure in which a separator is impregnated with an electrolytic solution.

(Separator)
The separator has a function of holding an electrolyte and ensuring lithium ion conductivity between the positive electrode and the negative electrode, and a function as a partition wall between the positive electrode and the negative electrode.

Examples of the form of the separator include a separator of a porous sheet made of a polymer or fiber that absorbs and retains the electrolyte, a non-woven fabric separator, and the like.

As the material constituting these separators, regardless of whether it is a microporous separator or a non-woven fabric separator, it is preferable that the material has an affinity with an organic electrolytic solution and can swell. Such a material is not particularly limited, and examples thereof include a material having cellulose, polyethylene glycol, or PVDF-HFP as a main skeleton. By swelling with the electrolytic solution, the pores are widened, and clogging by decomposition products can be suppressed without impairing the ionic conductivity. Further, it is desirable that the average pore diameter of the separator having these swellable materials as the main skeleton is 0.5 μm or more. With such a pore diameter, the pores are less likely to be blocked by the decomposition product and the movement of ions is less likely to be hindered, so that the cycle characteristics can be improved.

As another material that can be used for the separator, for example, a microporous (microporous membrane) can be used as long as it is a separator of a porous sheet made of a polymer or a fiber. Specific forms of the porous sheet made of the polymer or fiber include, for example, a polyolefin such as polyethylene (PE) and polypropylene (PP); a laminate in which a plurality of these are laminated (for example, three layers of PP / PE / PP). Examples thereof include a microporous (microporous film) separator made of a (structured laminate, etc.), a hydrocarbon resin such as polyimide, aramid, polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), and glass fiber.

The thickness of the microporous (microporous membrane) separator cannot be uniquely specified because it varies depending on the intended use. To give an example, in applications such as electric vehicles (EVs), hybrid electric vehicles (HEVs), and secondary batteries for driving motors such as fuel cell vehicles (FCVs), the length is 4 to 60 μm in a single layer or multiple layers. Is desirable.

As the material used for the nonwoven fabric separator, cotton, rayon, acetate, nylon, polyester; polyolefins such as PP and PE; polyimide, aramid and the like can be used, and these may be used alone or in combination.

Further, the bulk density of the nonwoven fabric is not particularly limited as long as sufficient battery characteristics can be obtained by the impregnated polymer gel electrolyte. Further, the thickness of the nonwoven fabric separator may be the same as that of the electrolyte layer, preferably 5 to 200 μm, and particularly preferably 10 to 100 μm.

(Electrolytes)
The electrolyte that infiltrates the separator is not particularly limited, but a liquid electrolyte or a gel polymer electrolyte is used. By using the gel polymer electrolyte, the distance between the electrodes is stabilized, the occurrence of polarization is suppressed, and the durability (cycle characteristics) is improved.

The liquid electrolyte has a function as a carrier of lithium ions. The liquid electrolyte constituting the electrolytic solution layer has a form in which a lithium salt as a supporting salt is dissolved in an organic solvent as a plasticizer. Examples of the organic solvent used include carbonates such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethylmethyl carbonate, and these are two or more kinds. It may be mixed and used. As the lithium _{salt, Li (CF 3 SO 2)} 2 N, Li (C 2 F 5 SO 2) 2 N, LiPF 6, LiBF 4, LiClO 4, LiAsF 6, LiTaF such 6, LiCF ₃ SO ₃ Compounds that can be added to the active material layer of the electrode can be similarly employed. The liquid electrolyte may further contain additives other than the above-mentioned components. Specific examples of such compounds include, for example, vinylene carbonate, methylvinylene carbonate, dimethylvinylene carbonate, phenylvinylene carbonate, diphenylvinylene carbonate, ethylvinylene carbonate, diethylvinylene carbonate, vinylethylene carbonate, 1,2-divinylethylene carbonate. , 1-Methyl-1-vinylethylene carbonate, 1-methyl-2-vinylethylene carbonate, 1-ethyl-1-vinylethylenecarbonate, 1-ethyl-2-vinylethylenecarbonate, vinylvinylene carbonate, allylethylenecarbonate, vinyl Oxymethylethylene carbonate, allyloxymethylethylene carbonate, acrylicoxymethylethylene carbonate, methacryloxymethylethylene carbonate, ethynylethylene carbonate, propargylethylene carbonate, ethynyloxymethylethylene carbonate, propargyloxyethylene carbonate, methyleneethylene carbonate, 1,1- Examples thereof include dimethyl-2-methyleneethylene carbonate. Of these, vinylene carbonate, methylvinylene carbonate and vinylethylene carbonate are preferable, and vinylene carbonate and vinylethylene carbonate are more preferable. Only one of these cyclic carbonic acid esters may be used alone, or two or more thereof may be used in combination.

The gel polymer electrolyte has a structure in which the above-mentioned liquid electrolyte is injected into a matrix polymer (host polymer) made of an ionic conductive polymer. By using a gel polymer electrolyte as the electrolyte, the fluidity of the electrolyte is eliminated, and it is easy to block the ionic conductivity between the layers. Examples of the ionic conductive polymer used as the matrix polymer (host polymer) include polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene glycol (PEG), polyacrylonitrile (PAN), and polyvinylidene fluoride-hexafluoropropylene (polyvinylidene fluoride-hexafluoropropylene). PVdF-HEP), poly (methyl methacrylate (PMMA)) and copolymers thereof and the like.

The matrix polymer of the gel electrolyte can exhibit excellent mechanical strength by forming a crosslinked structure. In order to form a crosslinked structure, a suitable polymerization initiator is used, and a polymerizable polymer for forming a polymer electrolyte (for example, PEO or PPO) is subjected to thermal polymerization, ultraviolet polymerization, radiation polymerization, electron beam polymerization, etc. It may be polymerized.

[Current collector]
The material constituting the current collector is not particularly limited, but a metal is preferably used.

Specific examples of the metal include aluminum, nickel, iron, stainless steel, titanium, copper, and other alloys. In addition to these, a clad material of nickel and aluminum, a clad material of copper and aluminum, or a plating material of a combination of these metals can be preferably used. Further, the foil may be a metal surface coated with aluminum. Of these, aluminum, stainless steel, and copper are preferable from the viewpoint of electron conductivity and battery operating potential.

The size of the current collector is determined according to the intended use of the battery. For example, if it is used for a large battery that requires high energy density, a current collector having a large area is used. There is no particular limitation on the thickness of the current collector. The thickness of the current collector is usually about 1 to 100 μm.

[Positive current collector plate and negative electrode current collector plate]
The material constituting the current collector plates (25, 27) is not particularly limited, and known highly conductive materials conventionally used as current collector plates for lithium ion secondary batteries can be used. As the constituent material of the current collector plate, for example, metal materials such as aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof are preferable. From the viewpoint of light weight, corrosion resistance, and high conductivity, aluminum and copper are more preferable, and aluminum is particularly preferable. The same material may be used for the positive electrode current collector plate 27 and the negative electrode current collector plate 25, or different materials may be used.

[Positive lead and negative electrode lead]
Further, although not shown, the current collector and the current collector plate may be electrically connected via a positive electrode lead or a negative electrode lead. As the constituent material of the positive electrode and the negative electrode lead, a material used in a known lithium ion secondary battery can be similarly adopted. The part taken out from the exterior is heat-shrinkable with heat-resistant insulation so that it does not affect the product (for example, automobile parts, especially electronic devices) by contacting peripheral devices and wiring and causing electric leakage. It is preferable to cover with a tube or the like.

[Reference electrode]
Examples of the material constituting the reference electrode 31 include Li metal and Sn—Li alloy. The reference electrode 31 of the present embodiment may be formed by coating or attaching a material constituting the reference electrode 31 to the tip end portion of the reference electrode terminal lead 33. In the form of coating the reference electrode 31, tin is plated on the tip of the thin nickel wire to be the reference electrode terminal lead 33, and this is reduced in a lithium electrolytic solution and used as the Li-plated reference electrode 31. By way of example, but not limited to these. Further, the reference electrode 31 may be large enough to measure the potential with high accuracy, and the reference electrode 31 should be as small as possible between the positive electrode active material layer 15 and the negative electrode active material layer 13 so as not to affect the battery reaction. It is preferable to put it in.

The reference electrode terminal lead 33 connects the reference electrode 31 and the reference electrode tab 35. Therefore, it is necessary to be electronically insulated from the positive electrode active material layer 15 and the negative electrode active material layer 13, and a part of the reference electrode terminal lead 33 is also electronically insulated from the positive electrode active material layer 15 and the negative electrode active material layer 13. It can be installed inside an insulated electrolyte layer (separator 17). The reference electrode terminal lead 33 does not function as the reference electrode 31, but may function as a terminal lead that takes out the potential of the reference electrode 31 to the outside. From the above, examples of the material constituting the reference electrode terminal lead 33 include Ni metal, stainless steel, and Fe metal.

The reference electrode tab 35 is joined between the laminated sheets constituting the battery exterior body 29, and has a structure taken out to the outside of the laminated battery 10. With such a structure, it is possible to prevent external impact and environmental deterioration during use. In particular, when used in a battery system for an electric vehicle, it is preferable to have a certain thickness so that the portion of the reference electrode tab 33 taken out to the outside of the battery is not broken by an impact from the outside. As the reference electrode tab 35, the same material and thickness as the electrode current collector plates 27 and 25 can be cut to a predetermined width and used. As the material constituting the reference electrode tab 35, for example, metal materials such as aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof are preferable. Further, the laminated battery 10 of the reference electrode tab 35 may be taken out from a different side from the electrode current collector plates 27 and 25 as shown in FIG. 1, or may be taken out from the same side.

[Battery exterior]
As the battery exterior 29, a known metal can case can be used, or a bag-shaped case using a laminated film containing aluminum that can cover the power generation element can be used. As the laminated film, for example, a laminated film having a three-layer structure in which PP, aluminum, and nylon are laminated in this order can be used, but the laminated film is not limited thereto. A laminated film is desirable from the viewpoint of high output, excellent cooling performance, and suitable use for batteries for large equipment for EVs and HEVs. Further, since the group pressure applied to the power generation element from the outside can be easily adjusted and the thickness of the electrolytic solution layer can be easily adjusted, an aluminumate laminate is more preferable for the exterior body.

[Cell size]
As shown in FIGS. 1 and 2A and 2B, the laminated battery 10 has a rectangular flat shape, and a positive electrode current collector plate 27 and a negative electrode current collector for extracting electric power from both sides thereof. The plate 25 is pulled out. The power generation element 21 is wrapped by the battery exterior body 29 of the laminated battery 10, and the periphery thereof is heat-sealed. The power generation element 21 has a positive electrode current collector plate 27 and a negative electrode current collector plate 25 pulled out to the outside. It is sealed with.

In the battery structure in which the power generation element is covered with an exterior body, the negative electrode active material layer has a rectangular shape (rectangular shape) because a large-sized battery is recently required for automobile applications and the like. The length of the short side is preferably 100 mm or more. Such large batteries can be used in vehicle applications. Here, the length of the short side of the negative electrode active material layer refers to the side having the shortest length among the electrodes. The upper limit of the length of the short side of the battery structure is not particularly limited, but is usually 400 mm or less. Further, the aspect ratio of the rectangular electrode is preferably 1 to 3, more preferably 1 to 2. The aspect ratio of the electrodes is defined as the aspect ratio of the rectangular positive electrode active material layer. By setting the aspect ratio in such a range, the gas generated during charging can be uniformly discharged in the surface direction, which is preferable. As a result, the cycle durability (discharge capacity retention rate) when used for a long period of time can be improved.

Further, from the viewpoint of a high energy density battery, which is different from the viewpoint of the physical size of the electrode, in the non-aqueous electrolyte secondary battery according to the present invention, the battery has a high density due to the relationship between the battery volume and the battery capacity. It is stipulated that. Specifically, in the non-aqueous electrolyte secondary battery according to the present invention, the value of the ratio of the battery volume (the product of the projected area of the battery including the battery exterior and the thickness of the battery) to the rated capacity is 10 cm ³ / Ah. It is as follows. Further, the rated capacity of the non-aqueous electrolyte secondary battery according to the present invention is 3 Ah or more. This large-sized battery has a large battery capacity per unit volume, in other words, the battery volume per unit capacity (ratio of the battery volume to the rated capacity) is small (10 cm ³ / Ah or less), and the battery capacity (rated capacity). Is specified as large (3Ah or more).

When the value of the ratio of the battery volume (the product of the projected area of the battery including the battery exterior and the thickness) to the rated capacity ^{exceeds 10 cm 3} / Ah, as described above, the problem to be solved by the present invention in the first place. It can be said that it is not necessary to apply the solution because the problem does not occur. Further, when the rated capacity is less than 3 Ah, the problem to be solved by the present invention does not occur because the capacity is small, and it is insufficient to make a large-sized battery.

The upper limit of the ratio of the battery volume (the product of the projected area and the thickness of the battery including the battery exterior) to the rated capacity is preferably 8 cm ³ / Ah or less. On the other hand, the lower limit of the value of the ratio of the battery volume (the product of the projected area and the thickness of the battery including the battery exterior) to the rated capacity is not particularly limited, but ^{it may be 2 cm 3} / Ah or more. It is preferably 3 cm ³ / Ah or more. The rated capacity is preferably 5 Ah or more, more preferably 10 Ah or more, further preferably 15 Ah or more, particularly preferably 20 Ah or more, and particularly preferably 25 Ah or more. Only when such a high-capacity and high-density battery is used, the problem of deterioration of the cycle durability of the non-aqueous electrolyte secondary battery becomes apparent due to the generation of oxygen gas from the solid solution positive electrode active material. On the other hand, in a battery such as a conventional consumer battery, which has a high capacity and is not high density as described above, even if oxygen gas is generated from the solid solution positive electrode active material, the cycle of the non-aqueous electrolyte secondary battery is accompanied by the oxygen gas. There is no decrease in durability.

The rated capacity of the non-aqueous electrolyte secondary battery is determined by the following.

(Measuring method of rated capacity)
The rated capacity of the test battery is measured by the following steps 1 to 5 in the voltage range of 3.0 V to 4.15 V at a temperature of 25 ° C. after injecting the electrolytic solution and leaving it for about 10 hours. To.

Step 1: After reaching 4.15V with a constant current charge of 0.1C, rest for 5 minutes.

Step 2: After step 1, charge for 1.5 hours with constant voltage charging and rest for 5 minutes.

Step 3: After reaching 3.0V by constant current discharge of 0.1C, discharge by constant voltage discharge for 2 hours, and then rest for 10 seconds.

Step 4: After reaching 4.1 V by constant current charging of 0.1 C, charge by constant voltage charging for 2.5 hours, and then rest for 10 seconds.

Step 5: After reaching 3.0 V by constant current discharge of 0.1 C, discharge by constant voltage discharge for 2 hours, and then stop for 10 seconds.

Rated capacity: The rated capacity is the discharge capacity (CCCV discharge capacity) in the discharge from the constant current discharge to the constant voltage discharge in step 5.

The battery volume is obtained by multiplying the projected area and the thickness of the battery including the battery exterior. Of these, regarding the projected area of the battery including the battery exterior, the projected area of the six batteries, front, back, right side, left side, plane, and bottom, can be obtained, and the largest projected area of the battery is obtained. Is usually used, which is the projected area of the battery on a flat surface or a bottom surface when the battery is placed on a flat plate in the most stable state. In addition, the thickness of the battery including the battery exterior shall be measured when fully charged. Further, the thickness of the battery including the battery exterior is measured at 8 or more points in consideration of the variation depending on the measurement points, and these are averaged values. For example, in the embodiment described later, the thickness of the battery including the battery exterior is measured at or near the points where the two diagonal lines of the power generation element are each divided into five equal parts (9 points in total), and these are averaged. did.

<< Manufacturing method of non-aqueous electrolyte secondary battery >>
One embodiment of the present invention relates to a method for manufacturing a non-aqueous electrolyte secondary battery. Here, in the method for manufacturing a non-aqueous electrolyte secondary battery according to the present embodiment, when a high-capacity and high-density non-aqueous electrolyte secondary battery is manufactured using the solid solution positive electrode active material and the silicon-containing negative electrode active material. , The power generation element containing the solid solution positive electrode active material to be activated is subjected to activation treatment (charging treatment). This activation treatment (charging treatment) causes a reorganization of the crystal structure of the solid solution positive electrode active material (change from a layered structure (Li ₂ MnO ₃ ) to a spinel structure (LiMn ₂ O ₄ )), thereby causing a solid solution positive electrode. Higher capacity of active material can be achieved. As described above, the solid solution positive electrode active material whose capacity has been increased through the activation treatment is referred to as "activated solid solution positive electrode active material" in the present specification. As for the manufacturing process before the activation treatment, conventionally known knowledge regarding the manufacturing of the non-aqueous electrolyte secondary battery can be appropriately referred to.

In the method for manufacturing a non-aqueous electrolyte secondary battery according to the present embodiment, in order to perform the activation treatment of the solid solution positive electrode active material, after forming the cell, the power generation element containing the solid solution positive electrode active material to be activated is charged. The treatment (or charge / discharge treatment) may be performed. At this time, conventionally known knowledge is appropriate for the specific conditions necessary for causing the reorganization of the crystal structure (such as the lower limit of the charged state of the power generation element required for the reorganization of the crystal structure to occur). Can be referenced. As an example, the charging process (or charging / discharging process) may be performed until the maximum potential of the positive electrode in the power generation element charged by the charging process becomes 4.3 V or more with respect to the lithium metal counter electrode. Be done. The "solid solution positive electrode active material to be activated" is not particularly limited as long as it is a solid solution positive electrode active material that has room for reorganization of the crystal structure by the activation treatment, and is an active material that has not been activated at all. It may be present, or it may be an active material that has already been subjected to some activation treatment.

Here, the present inventors have studied a non-aqueous electrolyte secondary battery using the solid solution positive electrode active material as the positive electrode as described above, and have found a new problem. That is, when such a solid solution positive electrode active material is applied to a high-capacity and high-density (battery volume per battery capacity is small) battery, the cycle durability is lowered due to the generation of oxygen gas from the positive electrode active material. It turned out that there was a case.

For the purpose of solving such a problem, the present inventors have conducted diligent studies. As a result, the upper limit value of the charge state in the charge process (or charge / discharge process) in the activation process is defined, and the power generation element is subjected to the charge process (activation process) so as not to exceed the upper limit value. We found that the problem could be solved. In the prior art, there was no recognition that oxygen gas was generated in the high charge state region. Therefore, from the viewpoint of increasing the capacity of the solid solution positive electrode active material as much as possible, it is common to perform the activation treatment beyond the charging state of the upper limit value at which oxygen gas is generated. The above-mentioned solution that the present inventors have learned is contrary to such common sense in the prior art. That is, in the method for manufacturing a non-aqueous electrolyte secondary battery according to the present embodiment, in the activation process, the value of the charge state of the power generation element is set in advance from the relationship between the charge state of the power generation element and the amount of gas generated. The charge process (or charge / discharge process) in the activation process is controlled so as not to exceed the upper limit of the state. By performing such control, oxidation of the negative electrode due to generation of oxygen gas from the solid solution positive electrode active material is prevented. As a result, even if the charge / discharge capacity of the treatment is sacrificed to some extent, the capacity decrease due to the oxidation of the negative electrode and the imbalance of the A / C ratio are prevented, and finally the decrease in the cycle durability of the battery is suppressed. You can do it. Above all, in the preferred embodiment, when the value of the charge state of the power generation element reaches the predetermined upper limit value in the activation process, the charge process in the activation process is terminated. With such a configuration, it is possible to perform the activation treatment so that the generation of oxygen gas can be suppressed to the minimum and the maximum capacity can be expressed.

FIG. 3A is a block diagram showing a configuration including a control device for carrying out an activation treatment, among the methods for manufacturing a non-aqueous electrolyte secondary battery according to an embodiment of the present invention. 3B shows a charging state (positive electrode capacity), a positive electrode potential (●), and an oxygen gas generation amount (◯), which are the basis for setting an upper limit value of the charging state stored in the control device (particularly the storage unit) of FIG. 3A. It is a figure which shows an example of the relationship with).

As shown in FIG. 3A, the control device for the non-aqueous electrolyte secondary battery according to the present embodiment is a solid solution positive electrode contained in the above-mentioned laminated battery 10 (including a power generation element containing a solid solution positive electrode active material to be activated). The charging device 200 is controlled when the active material is subjected to the activation treatment. The control device includes a control unit 100, a current sensor 110, and a voltage sensor 120 as a configuration for controlling the charging device 200.

The control unit 100 according to the present embodiment controls the charging process (or charging / discharging process) in the activation process of the power generation element 21 constituting the laminated battery 10 by controlling the charging device 200. The control unit 100 has a control unit such as a CPU or MPU, and a storage unit such as a ROM or RAM. The control unit 100 has a charge / discharge current (= charge / discharge current flowing through the power generation element 21) detected by the current sensor 110 and a terminal voltage (=) of the laminated battery 10 detected by the voltage sensor 120. Based on the terminal voltage of the power generation element 21), the charge and discharge of the power generation element 21 are controlled, and the charge state of the power generation element 21, specifically, the SOC value (State of Charge) is calculated. In the present embodiment, the control unit 100 determines the current flowing through the laminated battery 10 (current flowing through the power generation element 21) in order to execute the method for manufacturing the laminated battery 10 including the activation process described below. Detect at 110. Further, the control unit 100 detects the terminal voltage of the laminated battery 10 (= the terminal voltage of the power generation element 21) with the voltage sensor 120.

In the storage unit (not shown) of the control unit 100 according to the present embodiment, the upper limit value of the charging state when charging the power generation element 21 is stored in advance. The control unit 100 executes the activation process (charging process or charge / discharge process) so as not to exceed this upper limit value.

Here, the upper limit of the state of charge is set as follows. That is, a specific example will be described in detail in the section of Examples, but as a result of verification by the present inventors, the charge state of the laminated battery 10 (= charge state of the power generation element 21 (positive electrode capacity)) and oxygen gas generation. The relationship with the quantity is as shown in the graph indicated by the circle in FIG. 3B. That confirms the oxygen gas generation amount of the lithium ion secondary battery has been charged to the various volumes, the amount of oxygen gas is rapidly increased by the positive electrode capacity C ₁ in the boundary. On the other hand, the relationship between the charged state of the laminated battery 10 (= the charged state of the power generation element 21 (positive electrode capacity)) and the positive electrode potential (potential with respect to the lithium metal counter electrode) is as shown in the graph shown by ● in FIG. 3B. .. Thus, state of charge (positive electrode capacity) - Sets the positive electrode potential E _MAX corresponding to the charging state (the positive electrode capacity C ₁₎ generation of oxygen gas in the graph of the oxygen gas generation amount is rapidly increased as the upper limit of the state of charge , prevented in the charging process or the charge-discharge process for the activation treatment positive electrode potential E if not to exceed the upper limit value E _MAX, the generation of oxygen gas from the solid solution positive electrode active material constituting the positive electrode of the power generating element 21 can do. As a result, it is possible to effectively prevent a decrease in cycle durability due to the generation of oxygen gas. The upper limit of the power generation element (positive electrode capacity) for carrying out the control of the present invention varies depending on the type and blending amount of the solid solution positive electrode active material used, other materials and blending amounts contained in each active material layer, and the like. It can vary depending on the factors of. However, by conducting a preliminary study as shown in FIG. 3B, it is possible to inductively obtain an upper limit value of the power generation element (positive electrode capacity) for carrying out the control of the present invention. The upper limit (positive electrode potential E _MAX corresponding to the state of charge generation of oxygen gas is rapidly increased (positive electrode capacity C _1)), for example, positive electrode capacity shown in FIG. 3B - in the graph of gas generation, the differential The positive electrode capacity at the point where the coefficient (the limit value of ΔC → 0 for ΔA / ΔC when the capacity is C and the amount of gas generated is A) is 200 or more is C1, and the corresponding positive electrode potential is _EMAX . Can be determined by doing.

On the other hand, according to the estimation by the present inventors, it is considered that the upper limit value of the power generation element (positive electrode capacity) for carrying out the control of the present invention can be calculated deductively. That is, in the crystal structure of the lithium-containing transition metal oxide constituting the solid solution positive electrode active material, lithium ions are preferentially released from the 3b site and the 4h site at the initial stage of charging during the active treatment. When the charging process is continued after that, lithium ions are also released from the 2c site, and as a result, the orbital interaction between Li (2b) and O-Li (2c) is reduced, and the oxygen atom becomes molecular oxygen ( The present inventors presume that it is released to the outside of the crystal structure as _{O 2).} Therefore, in the crystal structure of the lithium-containing transition metal oxide constituting the solid solution positive electrode active material, lithium present at the 3b site and the 4h site among all the sites (3b, 4h, 2b, 2c) where lithium ions can exist. It is considered that the generation of oxygen gas can be prevented by performing the charging treatment during the activation treatment so that only the ions are released. Here, for example, in the lithium-containing transition metal oxide having the composition represented by the above-mentioned chemical formula (1), the composition ratio of lithium is represented by (1 + d). In the present specification, out of this (1 + d) mol of lithium, the amount of lithium released by the activation treatment (charging treatment) (that is, contributing to charging) is referred to as "lithium utilization amount". do. If the amount of lithium used is equal to or less than the amount of lithium existing at the 3b site and the 4h site, it is considered that the generation of oxygen gas is prevented. Therefore, based on this, a power generation element (positive electrode capacity) for carrying out the control of the present invention so that the amount of lithium utilized in the activation treatment (charging treatment) is equal to or less than the amount of lithium existing at the 3b site and the 4h site. ) Can be calculated.

Here, in the calculation of the general charge state SOC, the open circuit voltage of the laminated battery 10 (= power generation element 21) (voltage between both terminals of the laminated battery 10 in the no-load state) is used by the voltage sensor 120. Can be done. However, the generation of oxygen gas from the solid solution positive electrode active material constituting the positive electrode of the laminated battery 10 (that is, the power generation element 21) is due to the structural change of the active material due to the release of lithium ions from the solid solution positive electrode active material in the charged state. Occurs. Accordingly, in the control of suppressing the generation of oxygen gas as in the present embodiment, it is preferable to control so as not to exceed the upper limit E _MAX of the cathode potential with a reference electrode 31 for measuring the above-mentioned positive electrode potential E .. Here, the current sensor 110 and the voltage sensor 120 shown in FIG. 3A, and the reference electrode 31 shown in FIG. 2B and the like function as a charge state detection sensor.

In the above, the case where the control of the present invention is applied to the activation treatment of the solid solution positive electrode active material in the method for producing a non-aqueous electrolyte secondary battery according to the embodiment of the present invention has been described. However, the control of the present invention can also be applied when the non-aqueous electrolyte secondary battery is used (during operation). That is, the present invention can also be used for charging (or charging / discharging) when using a non-aqueous electrolyte secondary battery (the positive electrode contains an activated solid solution positive electrode active material) manufactured through the above-mentioned activation treatment. The controls of the invention are applicable. Hereinafter, the control of the non-aqueous electrolyte secondary battery according to the present invention mounted on the electric vehicle during use (during operation) will be described.

FIG. 4 is a block diagram showing an electric vehicle equipped with a non-aqueous electrolyte secondary battery according to an embodiment of the present invention.

As shown in FIG. 4, the electric vehicle 300 according to the present embodiment includes the above-mentioned laminated battery 10, the above-mentioned control device (including a control unit 100, a current sensor 110, and a voltage sensor 120), an inverter 310, and an inverter 310. It includes a motor 320. Since the control unit 100, the current sensor 110, and the voltage sensor 120 have the same configuration as the control unit 100, the current sensor 110, and the voltage sensor 120 shown in FIG. 3A, the description thereof will be omitted. Since the electric vehicle 300 shown in FIG. 4 includes the laminated battery 10 and the control device described above, it can be said that the electric vehicle 300 is a non-aqueous electrolyte secondary battery system.

The inverter 310 converts the DC power generated by the laminated battery 10 into AC power and gives it to the motor 320 to drive the motor 320 to drive the electric vehicle 300. Further, the inverter 310 converts the regenerative power, which is the AC power generated by the motor 320 when the electric vehicle 300 is braked, into DC power and gives it to the laminated battery 10, and charges the laminated battery 10.

When the laminated battery 10 is charged by the regenerative power generated by the motor 320 in this way, the control of the present invention can be applied. That is, in the present embodiment, the control unit 100 controls the charging process (or charging / discharging process) by the regenerative power when the laminated battery 10 is used (when the electric vehicle 300 is running) in the same manner as described above. Specifically, the charge state shown in FIG. 3B (the positive electrode capacity) - charging the positive electrode potential E _MAX generation of oxygen gas generation amount of the oxygen gas in the graph is equivalent to the state of charge increases rapidly (the positive electrode capacity C ₁₎ set the upper limit of the state, in the charging process by regenerative power (or the charge-discharge process) is positive electrode potential E if not to exceed the upper limit value E _MAX, from a solid solution positive electrode active material constituting the positive electrode of the power generating element 21 It is possible to prevent the generation of oxygen gas. As a result, it is possible to effectively prevent a decrease in cycle durability due to the generation of oxygen gas. Of course, in the control as in the present embodiment, similarly to the above, it is preferable to control so as not to exceed the upper limit E _MAX of the cathode potential with a reference electrode 31 for measuring the positive electrode potential E. With such a configuration, it is possible to use as much regenerative power as possible for charging the power generation element 21 while suppressing the generation of oxygen gas to the minimum.

In the above description, an application example of the control of the present invention when the laminated battery 10 is used has been described by exemplifying the control of the charging process by the regenerative power when the electric vehicle is running. However, the control of the present invention can also be applied to, for example, a normal charging process of the laminated battery 10 using a charging device.

The effects of the present invention will be described with reference to the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples.

[Example 1]
(Preparation of positive electrode sample)
A conventionally known composite of a lithium-containing transition metal oxide which is a solid solution containing _{Li 2} MnO ₃ and LiNi _0.375 Co _0.375 Mn _0.25 O _{2 in} a molar ratio of 1: 9 as a positive electrode active material. Prepared using the carbonate method. The composition formula of this lithium-containing transition metal oxide is
Li [Ni _0.3375 Co _0.3375 Mn _0.325 [Li] _0.1 ] O _2.1
Met. When this is applied to the chemical formula (1), z = 2.1 (the number of oxygen satisfying the valence), a = b = 0.3375, c = 0.325, d = 0.1, a + b + c = 1. ..

90 parts by mass of the solid solution positive electrode active material (lithium-containing transition metal oxide) prepared in this manner, 1 part by mass of lyphite graphite and 4 parts by mass of acetylene black as a conductive auxiliary agent, and polyvinylidene fluoride (PVDF) as a binder. 5 parts by mass and 74 parts by mass of N-methyl-2-pyrrolidone (NMP) as a viscosity adjusting solvent were prepared. Then, 5 parts by mass of PVDF was dissolved in 50 parts by mass of NMP to prepare a binder solution. Next, 1 part by mass of flake graphite, 4 parts by mass of acetylene black (5 parts by mass in total), and 90 parts by mass of the solid solution positive electrode active material (lithium-containing transition metal oxide) were added to 60 parts by mass of the binder solution. The mixture was kneaded with a planetary mixer (Hibismix 2P-03 type manufactured by Primex Co., Ltd.), and then 24 parts by weight of NMP was added to the kneaded product to obtain a positive electrode active material slurry (solid content concentration 60% by mass).

Then, the positive electrode active material slurry was applied to one side of a 20 μm-thick (sheet-shaped) aluminum current collector foil as a current collector by a bar coater (the mass of the positive electrode active material layer after drying was approximately 3.5 mg / cm ² ). (To be) applied. Subsequently, the current collector foil coated with the positive electrode active material slurry was dried on a hot plate (120 ° C. to 130 ° C., drying time 10 minutes) to form a positive electrode active material layer. By this drying treatment, the amount of NMP remaining in the positive electrode active material layer was set to 0.02% by mass or less. In this way, a sheet-shaped positive electrode was obtained.

Next, the sheet-shaped positive electrode is compression-molded by a roller press and cut to make the mass of the positive electrode active material layer on one side about 3.5 mg / cm ² , the thickness about 50 μm, and the density 2.70 g /. Adjusted to cm ^3.

Then, the sheet-shaped positive electrode was dried in a vacuum drying oven. After installing the sheet-shaped positive electrode inside the drying oven, the pressure was reduced (100 mmHg (1.33 × 10 ⁴ Pa)) at room temperature (25 ° C.) to remove the air in the drying oven. Subsequently, while flowing nitrogen gas (100 cm ³ / min), the temperature was raised to 120 ° C. at 10 ° C./min, the pressure was reduced again at 120 ° C., and the nitrogen in the furnace was kept exhausted for 12 hours, and then at room temperature. The temperature dropped to. In this way, the positive electrode sample was completed.

(Making a cell for measuring gas generation)
A microporous film made of polypropylene (PP) prepared as a separator by cutting out the positive electrode sample prepared above and putting it inside a piezoelectric AE sensor (VS900-M manufactured by Vallen system) so that the positive electrode active material layer is exposed. (Thickness 25 μm) and a lithium metal foil as a negative electrode (thickness 200 μm) were laminated in this order. _{Next, LiPF 6} as a supporting salt was added to an organic solvent in which an electrolytic solution (ethylene carbonate (EC) and diethyl carbonate (DEC) was mixed at a ratio of EC: DEC = 1: 2 (volume ratio)) at a concentration of 1 M (mol). / L) was dissolved using a syringe) and sealed to complete the cell for measuring gas generation.

(Activation treatment for gas generation measurement cell)
The gas generation measurement cell produced above is placed inside a constant temperature bath (25 ° C.) to control the temperature, and in that state, a charge / discharge tester: HJ0501SM8A (manufactured by Hokuto Denko Co., Ltd.) is used for gas generation measurement. The cell was charged once. In this charging process, charging is performed up to 4.8 V using a constant current method with a charging current of 0.1 C, and then charging is performed using a constant voltage method of 4.8 V until the charging capacity of the positive electrode reaches 320 mAh / g. rice field. Here, the current density of 1C means a current value at which the discharge ends when a cell having a nominal capacity value a [Ah] is discharged at a constant current for 1 hour, and in this case, 1C = a [A].

In this charging process, the terminal voltage (open circuit voltage) between the positive and negative electrodes of the gas generation measurement cell was monitored over time using a voltage sensor. In addition, the gas generation event inside the gas generation measurement cell was also monitored over time by operating the piezoelectric AE sensor. From these results, the charge state (positive electrode capacity) of the gas generation measurement cell used in this example is plotted on the horizontal axis, and the positive electrode potential (●) and the amount of oxygen gas generated (oxygen gas generation event) with respect to metallic lithium (oxygen gas generation event) ( ◯) was plotted on the vertical axis to obtain the graph shown in FIG. 3B. As shown in FIG. 3B, it can be seen that the oxygen gas generation event (oxygen gas generation amount) sharply increases with the positive electrode capacity of 294 mAh / g as a boundary. It can also be seen that the positive electrode capacity of 294 mAh / g corresponds to 4.68 V as the positive electrode potential for the lithium metal. Therefore, by setting these positive electrode capacities (or positive electrode potentials) as upper limit values and performing activation treatment (charging treatment) of the solid solution positive electrode active material so as not to exceed this, oxygen gas in the activation treatment is performed. It was shown that the outbreak can be sufficiently suppressed. Further, even during normal use of the battery provided with the positive electrode used here, the positive electrode capacity (or positive electrode potential) obtained above is set as an upper limit value, and the power generation element of the battery is not exceeded. It was also shown that the charging process can sufficiently suppress the generation of oxygen gas during the charging process.

(Preparation of negative electrode sample)
As the silicon-containing negative electrode active material, _{a silicon-containing alloy having a composition of Si 65} Sn ₅ Ti ₃₀ (composition ratio is mass ratio) was produced by the following method.

Specifically, using a stirring ball mill device C-01M manufactured by ZOZ of Germany, 1920 g of zirconia crushed balls (φ5 mm) and 1 g of carbon (SGL) were put into a SUS crushing pot, and then at 1000 rpm for 10 minutes. A pre-crushing process was carried out. After that, 100 g of each raw material powder of the alloy (high-purity metal Si ingot (5N), high-purity Ti wire (3N), high-purity Sn plate (3N)) was added and alloyed at 1500 rpm for 5 hours (alloying). Treatment), and then finely pulverized at 400 rpm for 1 hour to obtain a silicon-containing alloy (negative electrode active material). In the stirring ball mill device used in this embodiment, the revolution radius rs = 0.070 [m], the rotation radius rpl = 0 [m], and the rotation speed rpm = 1500 [times / minute]. The force is calculated as Gnl = 176.0 [G]. The average particle size (D50) of the obtained silicon-containing alloy (negative electrode active material) powder was 5.4 μm.

80 parts by mass of the silicon-containing negative electrode active material (Si ₆₅ Sn ₅ Ti ₃₀ powder) prepared in this manner, 5 parts by mass of acetylene black as a conductive auxiliary agent, and 15 parts by mass of polyamide-imide as a binder are mixed. , N-Methyl-2-pyrrolidone was dispersed in an appropriate amount to obtain a negative electrode active material slurry. Next, the obtained negative electrode active material slurry was uniformly applied to one side of a negative electrode current collector made of a copper foil (thickness 15 μm) so that the thickness of the negative electrode active material layer was 30 μm, and the negative electrode active material layer was uniformly applied in a vacuum for 24 hours. Drying gave a negative electrode sample.

(Preparation of test laminated cell)
The positive electrode sample obtained above is cut out so as to have an active material layer area; length 2.5 cm × width 2.0 cm, and these two sheets are placed so that the current collectors face each other so that the uncoated surface (aluminum current collector) is used. The surface where the foil slurry was not applied) was aligned and the current collector part was spot welded. As a result, a positive electrode having a positive electrode active material layer was formed on both sides of a double-layered current collector foil whose outer peripheral portion was integrated by spot welding. After that, an aluminum positive electrode tab (positive electrode current collector plate) was further welded to the current collector portion to form a positive electrode. That is, the positive electrode has a structure in which positive electrode active material layers are formed on both sides of the current collector foil.

On the other hand, the negative electrode sample obtained above is cut out so as to have an active material layer area; length 2.7 cm × width 2.2 cm, and then a negative electrode tab of electrolytic copper is welded to the current collector portion to form a negative electrode. Formed. That is, the negative electrode sample has a structure in which a negative electrode active material layer is formed on one side of a current collector.

A laminated power generation element consisting of five layers with a porous polypropylene separator (length 3.0 cm x width 2.5 cm, thickness 25 μm, porosity 55%) sandwiched between the negative electrode and the positive electrode to which these tabs are welded. Was produced. The configuration of the laminated power generation element was a negative electrode (single side) / separator / positive electrode (both sides) / separator / negative electrode (single side). Next, both sides of the power generation element were sandwiched between aluminum laminated film exterior materials (length 3.5 cm × width 3.5 cm), and the three sides were thermocompression-bonded to accommodate the power generation element. After injecting the same electrolytic solution 0.8 cm ^{3 as} above (in the case of the above five-layer configuration, a two-cell configuration and a liquid ^{injection amount of 0.4 cm 3} per cell) into this power generation element, the remaining one side is Temporarily sealed by thermocompression bonding to prepare a test laminated cell. In order to allow the electrolytic solution to sufficiently penetrate into the electrode pores, the mixture was held at 25 ° C. for 24 hours while being pressurized at a surface pressure of 0.5 MPa.

(Charging process of power generation element (activation process))
In this embodiment, the charge state of the power generation element corresponding to the positive electrode capacity of 294 mAh / g (4.68 V as the positive electrode potential for lithium metal) is set as the upper limit value by the preliminary study using the above-mentioned gas generation measurement cell. However, it has been found that the generation of oxygen gas from the power generation element (particularly the solid solution positive electrode active material) can be suppressed by performing the activation treatment so as not to exceed this upper limit value. Therefore, in this example, the test cell produced above was activated until it had a positive electrode capacity of 294 mAh / g (positive electrode potential for lithium metal was 4.68 V).

Specifically, first, charging was performed at 25 ° C. by a constant current charging method at 0.05 C for 4 hours (SOC of about 20%). Then, after charging to 4.45 V at a rate of 0.1 C at 25 ° C., charging was stopped and held in that state (SOC about 70%) for about 2 days (48 hours) (aging treatment). Next, one side temporarily sealed by thermocompression bonding was opened, gas was removed at 10 ± 3 hPa for 5 minutes, and then thermocompression bonding was performed again to perform temporary sealing. Further, it was formed under pressure (surface pressure 0.5 ± 0.1 MPa) with a roller, and the electrode and the separator were sufficiently brought into close contact with each other.

After that, as an activation process, charging was performed up to 4.68 V by a constant current method with a charging current of 0.1 C so as not to exceed the upper limit of the charged state of the above-mentioned power generation element. Then, after resting for 10 minutes, the activation process was performed by discharging to 2.0 V by a constant current method with a charging current of 0.1 C. The theoretical lithium utilization amount during charging in the activation treatment in this example was calculated to be 0.941.

In addition, the amount of oxygen gas generated before and after the activation treatment was measured by the Archimedes method from the volume change of the test laminate cell before and after the activation treatment. The results are shown in Table 1 below.

(Cycle durability evaluation)
The cycle durability of the test cell subjected to the above activation treatment was evaluated. Specifically, under room temperature conditions, a constant current constant voltage charging method is used in which the battery is charged with a charging current of 0.1 C until the battery voltage reaches 4.5 V, and then held for about 1 hour to 1.5 hours. The constant current method was used in which the battery was discharged with a discharge current of 0.1 C until the battery voltage reached 2.0 V. This cycle was repeated 50 times, and the ratio of the discharge capacity in the 50th cycle to the discharge capacity in the first cycle was evaluated as the "capacity retention rate (%)". The results are shown in Table 1 below:
Capacity retention rate (%) = Discharge capacity in the 50th cycle / Discharge capacity in the 1st cycle x 100
The values of charge capacity and discharge capacity in the first cycle, the value of the rated capacity of the test laminate cell, and the battery volume with respect to the rated capacity of the test laminate cell (projected area of the battery including the battery exterior and the thickness of the battery). The value of the ratio of) is also shown in Table 1 below.

[Example 2]
A conventionally known composite of a lithium-containing transition metal oxide which is a solid solution containing _{Li 2} MnO ₃ and LiNi _0.375 Co _0.375 Mn _0.25 O _{2 in} a molar ratio of 3: 7 as a positive electrode active material. Prepared using the carbonate method. The composition formula of this lithium-containing transition metal oxide is
Li [Ni _0.2625 Co _0.2625 Mn _0.475 [Li] _0.3 ] O _2.3
Met. When this is applied to the chemical formula (1), z = 2.3 (the number of oxygen satisfying the valence), a = b = 0.2625, c = 0.475, d = 0.3, a + b + c = 1. ..

A cell for measuring gas generation was produced by the same method as in Example 1 described above except that the positive electrode active material thus obtained was used, and the amount of oxygen gas generated from the solid solution positive electrode active material suddenly increased. The upper limit of the charging state of the increasing positive electrode was investigated.

Next, a test laminate cell was prepared by the same method as in Example 1 described above except that the positive electrode active material obtained in this example was used, and the activation treatment and the measurement of the amount of oxygen gas generated at that time were measured. , And cycle durability was evaluated. The results are shown in Table 1 below. The theoretical lithium utilization amount during charging in the activation treatment in this example was calculated to be 1.057.

[Example 3]
A conventionally known composite of a lithium-containing transition metal oxide, which is a solid solution containing _{Li 2} MnO ₃ and LiNi _0.375 Co _0.375 Mn _0.25 O _{2 in} a molar ratio of 5: 5, as a positive electrode active material. Prepared using the carbonate method. The composition formula of this lithium-containing transition metal oxide is
Li [Ni _0.1875 Co _0.1875 Mn _0.625 [Li] _0.5 ] O _2.5
Met. When this is applied to the chemical formula (1), z = 2.5 (the number of oxygen satisfying the valence), a = b = 0.1875, c = 0.625, d = 0.5, a + b + c = 1. ..

A cell for measuring gas generation was produced by the same method as in Example 1 described above except that the positive electrode active material thus obtained was used, and the amount of oxygen gas generated from the solid solution positive electrode active material suddenly increased. The upper limit of the charging state of the increasing positive electrode was investigated.

Next, a test laminate cell was prepared by the same method as in Example 1 described above except that the positive electrode active material obtained in this example was used, and the activation treatment and the measurement of the amount of oxygen gas generated at that time were measured. , And cycle durability was evaluated. The results are shown in Table 1 below. The theoretical lithium utilization amount during charging in the activation treatment in this example was calculated to be 1.088.

[Example 4]
A conventionally known composite of a lithium-containing transition metal oxide which is a solid solution containing _{Li 2} MnO ₃ and LiNi _0.375 Co _0.375 Mn _0.25 O _{2 in} a molar ratio of 7: 3 as a positive electrode active material. Prepared using the carbonate method. The composition formula of this lithium-containing transition metal oxide is
Li [Ni _0.1125 Co _0.1125 Mn _0.775 [Li] _0.7 ] O _2.7
Met. When this is applied to the chemical formula (1), z = 2.7 (the number of oxygen satisfying the valence), a = b = 0.1125, c = 0.775, d = 0.7, a + b + c = 1. ..

A cell for measuring gas generation was produced by the same method as in Example 1 described above except that the positive electrode active material thus obtained was used, and the amount of oxygen gas generated from the solid solution positive electrode active material suddenly increased. The upper limit of the charging state of the increasing positive electrode was investigated.

Next, a test laminate cell was prepared by the same method as in Example 1 described above except that the positive electrode active material obtained in this example was used, and the activation treatment and the measurement of the amount of oxygen gas generated at that time were measured. , And cycle durability was evaluated. The results are shown in Table 1 below. The theoretical lithium utilization amount during charging in the activation treatment in this example was calculated to be 1.057.

[Comparative Example 1]
During the charging process in the activation process, charging was performed to a state of charge exceeding the upper limit of the state of charge of the above-mentioned power generation element. Specifically, the activation treatment (charging treatment) was performed so that the theoretical lithium utilization amount at the time of charging in the activation treatment was 1.093. Other than that, a test laminated cell was prepared by the same method as in Example 1 described above, and the activation treatment, the measurement of the amount of oxygen gas generated at that time, and the cycle durability evaluation were performed. The results are shown in Table 1 below.

[Comparative Example 2]
During the charging process in the activation process, charging was performed to a state of charge exceeding the upper limit of the state of charge of the above-mentioned power generation element. Specifically, the activation treatment (charging treatment) was performed so that the theoretical lithium utilization amount at the time of charging in the activation treatment was 1.154. Other than that, a test laminated cell was prepared by the same method as in Example 2 described above, and the activation treatment, the measurement of the amount of oxygen gas generated at that time, and the cycle durability evaluation were performed. The results are shown in Table 1 below.

[Comparative Example 3]
During the charging process in the activation process, charging was performed to a state of charge exceeding the upper limit of the state of charge of the above-mentioned power generation element. Specifically, the activation treatment (charging treatment) was performed so that the theoretical lithium utilization amount at the time of charging in the activation treatment was 1.176. Other than that, a test laminated cell was prepared by the same method as in Example 3 described above, and the activation treatment, the measurement of the amount of oxygen gas generated at that time, and the cycle durability evaluation were performed. The results are shown in Table 1 below.

[Comparative Example 4]
During the charging process in the activation process, charging was performed to a state of charge exceeding the upper limit of the state of charge of the above-mentioned power generation element. Specifically, the activation treatment (charging treatment) was performed so that the theoretical lithium utilization amount at the time of charging in the activation treatment was 1.150. Other than that, a test laminated cell was prepared by the same method as in Example 4 described above, and the activation treatment, the measurement of the amount of oxygen gas generated at that time, and the cycle durability evaluation were performed. The results are shown in Table 1 below.

As can be seen from the results shown in Table 1, in Examples 1 to 4, the control of the present invention was applied to the activation treatment (charging treatment) of the solid solution positive electrode active material at the time of manufacturing the lithium ion secondary battery. It can be seen that the generation of oxygen gas during the activation treatment was suppressed, and that the cycle durability of the battery was significantly improved. On the other hand, in Comparative Examples 1 to 4 to which the control of the present invention was not applied, a large amount of oxygen gas was generated during the activation treatment, and the cycle durability of the battery was significantly reduced due to this. Recognize.

Here, for Example 3 and Comparative Example 3 described above, a graph plotting the discharge capacity in each cycle of the cycle durability test is shown in FIG. 5A. As shown in FIG. 5A, a high-capacity and high-density battery as in Example 3 and Comparative Example 3 described above (battery volume with respect to the rated capacity of the battery (projected area of the battery including the battery exterior and thickness of the battery). (Product) ratio value is 10 cm ³ / Ah or less, and the rated capacity is 3 Ah or more), when the control of the present invention is performed (Example 3) and when it is not performed (Example 3). It can be seen that there is a large difference in cycle durability from Comparative Example 3).

On the other hand, the value of the ratio of the high-capacity and high-density battery as described above (the product of the battery volume (the product of the projected area of the battery including the battery exterior and the thickness of the battery) to the rated capacity of the battery) is 10 cm ³ / Ah or less. The discharge capacity in each cycle of the cycle durability test when the same comparative experiment (cycle durability test) as in FIG. 5A is performed using a battery that is not (a battery having a rated capacity of 3 Ah or more). The graph in which is plotted is shown in FIG. 5B. As shown in FIG. 5B, in a battery that does not satisfy the condition of "high capacity and high density", there is almost a difference in cycle durability between the case where the control of the present invention is performed and the case where the control of the present invention is not performed. I know I can't.

Based on the above, the method for manufacturing and controlling the non-aqueous electrolyte secondary battery, the control device, and the non-aqueous electrolyte secondary battery system according to the present invention are high-capacity and high-density batteries containing a solid solution positive electrode active material in the positive electrode. It can be seen that the peculiar problem (decrease in cycle durability due to generation of oxygen gas in a high potential state) can be solved.

10 stacked batteries,
11 Negative electrode current collector,
12 Positive electrode current collector,
13 Negative electrode active material layer,
15 Positive electrode active material layer,
17 Electrolyte layer,
19 Single battery layer,
21 Power generation element,
25 Negative electrode current collector plate (negative electrode tab),
27 Positive electrode current collector plate (positive electrode tab),
29 Battery exterior,
31 reference electrode,
33 Reference electrode terminal lead,
35 Reference Electrode Tab,
100 control unit,
110 current sensor,
120 voltage sensor,
200 charging device,
300 electric car,
310 inverter,
320 motor.

Claims (4)

A power generation element including a positive electrode containing an activated solid solution positive electrode active material, a negative electrode containing a silicon-containing negative electrode active material, and an electrolyte layer containing a non-aqueous electrolyte interposed between the positive electrode and the negative electrode. It is a method for manufacturing a non-aqueous electrolyte secondary battery that has.
The value of the ratio of the battery volume (the product of the projected area of the battery including the battery exterior and the thickness of the battery) to the rated capacity of the non-aqueous electrolyte secondary battery is 10 cm ³ / Ah or less, and the rated capacity is Is 3Ah or more,
By subjecting the power generation element containing the solid solution positive electrode active material to be activated to a charging treatment at the manufacturing stage before using the non-aqueous electrolyte secondary battery, _{the layered structure Li 2} MnO ₃ in the solid solution positive electrode active material is applied. Includes activating treatment of the solid solution positive electrode active material by changing to _{LiMn 2} O ₄ having a spinel structure.
In the activation process, the charge process is controlled so that the value of the charge state of the power generation element does not exceed the upper limit value of the charge state set in advance from the relationship between the charge state of the power generation element and the amount of gas generated. A method for manufacturing a non-aqueous electrolyte secondary battery, further comprising. In the activation process, if the value of the charge state of the power generating element has reached the upper limit value, and terminates the charging process in the activation process, a manufacturing method of the nonaqueous electrolyte secondary battery according to claim 1 .. The solid solution positive electrode active material has the following chemical formula (1):
Li [Ni _a Co _b Mn _c [Li] _d ] O _z ... (1)
In the formula, Li is lithium, Ni is nickel, Co is cobalt, Mn is manganese, O is oxygen, z is the number of oxygen satisfying the atomic value, and a, b, c and d are 0 <a <. Satisfy the relationship of 0.94, 0 ≦ b <0.94, 0 <c <0.94, 0.2 ≦ d ≦ 0.6, a + b + c = 1.
The method for producing a non-aqueous electrolyte secondary battery according to claim 1 or 2 , which has a solid solution lithium-containing transition metal oxide having a composition represented by. The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 3 , wherein d satisfies 0.3 ≦ d ≦ 0.5.

Images