JP5136706B2 - Cathode material for non-aqueous electrolyte lithium ion battery and battery using the same - Google Patents

Description

  The present invention is a non-aqueous solution using lithium nickel oxide (in the present invention, a lithium nickel-based composite oxide containing lithium and nickel as main components, hereinafter also referred to as LiNi oxide) as a positive electrode material active material. The present invention relates to a positive electrode material for an electrolyte lithium ion battery and a non-aqueous electrolyte lithium ion battery using the same.

Currently, lithium ion secondary batteries are commercialized as non-aqueous electrolyte secondary batteries for portable devices such as mobile phones. This non-aqueous electrolyte lithium-ion secondary battery needs to be made thinner as the portable device becomes lighter and thinner. Recently, the development of a thin battery using a laminate film as an exterior material has progressed. Laminate type thin battery using lithium cobalt oxide (LiCoO ₂ ) as active material, graphite material or carbonaceous material as negative electrode active material, organic solvent or polymer electrolyte in which lithium salt is dissolved in non-aqueous electrolyte is put into practical use It is being done.

Furthermore, in recent years, with the increase in functionality and performance of portable devices, the power consumption of the devices is increasing, and there is an increasing demand for higher capacity for batteries serving as power sources. Therefore, LiNi oxides (LiNiO ₂ and Li _x Ni _1-ab Co _a Al _b O ₂ ) that can be expected to have a higher capacity than conventional lithium cobalt oxides are being developed.

  Apart from these applications, in order to promote the introduction of electric vehicles (EV), hybrid vehicles (HEV), and fuel cell vehicles (FCV) against the backdrop of the recent increase in environmental protection movements, these motor drive power supplies and hybrid devices Auxiliary power supplies are being developed. Non-aqueous electrolyte lithium ion secondary batteries that can be repeatedly charged and discharged are also used for such applications. In applications where high output and high energy density are required, such as EV, HEV, FCV motor drive, etc., a single large battery cannot be made practically, and an assembled battery constructed by connecting a plurality of batteries in series. Is generally used. It has been proposed to use a laminate-type thin nonaqueous electrolyte lithium ion battery (simply referred to as a thin laminate battery) as one battery constituting such an assembled battery.

  Even in a thin laminated battery for such applications requiring high output and high energy density, the battery outer container is similarly changed to a metal sheet material. Specifically, a metal thin film such as aluminum foil and a resin film that physically protects a metal thin film such as polyethylene terephthalate and heat fusion such as an ionomer so that gas such as water vapor and oxygen is not exchanged inside and outside the container. A laminate sheet in which adhesive resin films are stacked to form a multilayer is used. The outer container of the thin laminated battery has a rectangular shape in plan view and has a predetermined thin shape. A battery is formed by inserting a plate-like positive electrode and negative electrode into an outer container and enclosing a liquid nonaqueous electrolyte.

  Such a thin laminate type battery is lightweight because it does not have an individual metal outer container, and even when the pressure inside the container becomes high due to overcharge or the like, and it ruptures, it has less impact than a metal container. Therefore, it is also suitable for applications that require high output and high energy density, such as EV, HEV, and FCV motor drives.

  Furthermore, the thin laminated battery used for such applications as high power and high energy density such as EV, HEV, FCV motor drive, etc. is the power source as in the case of the portable device described above. The demand for higher capacity has become stronger for batteries. Therefore, the development of LiNi oxides that can be expected to have a higher capacity than conventional lithium cobalt oxides is progressing.

  However, in a LiNi battery using a positive electrode material containing this LiNi oxide as a positive electrode active material (also simply referred to as LiNi positive electrode material), high-valence Ni ions in the positive electrode material oxidize oxygen ions. As a result, oxygen radicals are released and the electrolyte solution is decomposed. Therefore, a battery using the positive electrode material has a problem that a large amount of gas is generated due to gas generation at the electrode during initial charging or high-temperature storage, and the battery greatly expands.

  In order to solve the above problem, Patent Document 1 discloses a method of suppressing gas generation by controlling the pH of the positive electrode material.

JP 2002-203552 A

  However, in the method described in Patent Document 1, since a positive electrode material active material is obtained from a raw material hydroxide by a coprecipitation method, a hydroxyl group (OH) remains on the surface. The OH remaining on the surface suppresses radicals, but this method is effective only when moisture enters the cell. Even if the alkalinity of the material is suppressed by pH control, the temperature is high (60 ° C. or higher; when used in a car, especially in the vicinity of the engine room or motor) in an environment of about 60 ° C. when the voltage is high (charged). There is a problem that it does not function much in charging and discharging. That is, in a state where the voltage is high (charged state), the reaction proceeds spontaneously at a high temperature and gas is generated, so that there is a problem that it does not function so much during charge / discharge (during use).

  Therefore, the present invention has been focused on the above-mentioned problems of the prior art, and a positive electrode material for a non-aqueous electrolyte lithium ion battery capable of suppressing the decomposition of the electrolytic solution even during charge and discharge at high temperature, and It is an object of the present invention to provide a battery used, a submodule in which a plurality of the batteries are connected, a battery pack, and a vehicle equipped with these.

  The present invention is achieved by a positive electrode material for a non-aqueous electrolyte lithium ion battery comprising a lithium nickel oxide surface containing a Li compound attached thereto.

  According to the positive electrode material for a non-aqueous electrolyte lithium ion battery of the present invention, a battery using the positive electrode material is charged and discharged at a high temperature by attaching a Li compound to the surface of the LiNi oxide as a positive electrode material active material. However, generation of oxygen radicals from the LiNi oxide can be remarkably suppressed. Therefore, it is possible to suppress the decomposition of the electrolytic solution as much as possible and to greatly reduce the swelling of the battery.

It is drawing which represented typically the mode of the particle | grains by which Li compound was attached so that the surface of LiNi oxide used for the positive electrode material of this invention might be coat | covered (coat). It is drawing which represented typically the mode of the particle | grains by which Li compound was used so that it might be scattered on the LiNi oxide surface used for the positive electrode material of this invention. The cross-sectional schematic of the flat type (stacked type) non-aqueous electrolyte lithium ion secondary battery which is not a bipolar type is shown. 1 is a schematic cross-sectional view schematically showing the overall structure of a bipolar non-aqueous electrolyte lithium ion secondary battery. It is a schematic diagram which shows an example of the assembled battery which connected the bipolar battery of this invention in 2 series 20 parallel. 5 (a) is a plan view of the assembled battery, FIG. 5 (b) is a front view of the assembled battery, and FIG. 5 (c) is a right side view of the assembled battery. In (c), all show the inside of the assembled battery through the outer case so that it can be seen that the bipolar batteries are connected in series and in parallel. It is a figure which shows an example of the assembled battery which connected in parallel the bipolar battery A of this invention and the lithium ion secondary battery B10 which is not the bipolar type of this invention. FIG. 6A is a plan view of the assembled battery, FIG. 6B is a front view of the assembled battery, and FIG. 6C is a right side view of the assembled battery. In (c), the inside of the assembled battery is shown through the outer case so that it can be seen that the bipolar battery A and the non-bipolar lithium ion secondary battery B are connected in series and parallel mixing. . It is a figure which shows an example of the composite assembled battery of this invention. FIG. 7A is a plan view of the composite assembled battery, FIG. 7B is a front view of the composite assembled battery, and FIG. 7C is a right side view of the composite assembled battery. It is a schematic diagram which shows the electric vehicle of the state which mounts a composite assembled battery. It is explanatory drawing explaining the absolute maximum length used when measuring the particle size of particle | grains.

  The positive electrode material for a non-aqueous electrolyte lithium ion battery according to the present invention is characterized in that it contains a LiNi oxide surface with a Li compound attached thereto. Hereinafter, embodiments of the present invention will be described.

The LiNi oxide that can be used for the positive electrode material of the present invention is not particularly limited as long as it is used as a positive electrode active material, and conventionally known ones can be used. As described above, the LiNi oxide includes a lithium nickel composite oxide mainly composed of lithium and nickel. Examples of the LiNi oxide include, in addition to LiNiO ₂ , nickel metal partially substituted with other transition metal elements, such as LiNi _x Co _1-x O ₂ (0 <x <1), Composition formula (1);

(0 ≦ a ≦ 1.2, 0.3 ≦ b ≦ 0.85, 0 ≦ c ≦ 0.4, 0 ≦ d ≦ 0.6, 0 ≦ e ≦ 0.1, 0.9 ≦ b + c + d + e ≦ 1 .2, −0.05 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.05, M is at least one of Al, Mg, Ca, Ti, V, Cr, Fe, and Ga, and N is Lithium nickel-based composite oxide represented by (at least one of F, Cl, and S) can be used, but the present invention is not limited to these materials. These LiNi oxides, particularly the composition of the composition formula (1), can be measured by, for example, ICP (inductively coupled plasma emission spectrometry), atomic absorption method, fluorescent X-ray method, or particle analyzer.

  The average particle diameter of the LiNi oxide particles of the positive electrode material active material depends on its production method, but from the viewpoint of increasing the capacity, reactivity, and cycle durability of the LiNi oxide as the positive electrode material active material, Although it can be said that it is desirable to be in the range of 0.1 to 20 μm, the present invention is not necessarily limited to the above range. In addition, when the LiNi oxide is secondary particles, it can be said that the average particle diameter of the primary particles constituting the secondary particles is desirably in the range of 0.01 to 5 μm. It is not necessarily limited to the above range. However, it goes without saying that, depending on the manufacturing method, the LiNi oxide does not have to be secondary particles formed by aggregation, lump or the like. The particle diameter of the LiNi oxide particles and the particle diameter of the primary particles can be measured by, for example, SEM (scanning electron microscope) observation or TEM (transmission electron microscope) observation. The shape of the LiNi oxide and the Li oxide added to the oxide differs in the shape that can be taken depending on the type and manufacturing method, for example, spherical (powder), plate, needle, column, square However, the present invention is not limited to these, and any shape can be used without any problem. Preferably, an optimal shape that can improve battery characteristics such as charge / discharge characteristics is appropriately selected. Therefore, the particle size of the LiNi oxide particles mentioned above is expressed by the absolute maximum length because the shape of the particles is not uniform, and when sieving (mesh through size or mesh path size) May be used. Here, the absolute maximum length refers to the one having the maximum length L among the distances between any two points on the contour line of the particle 91 as shown in FIG.

Next, the Li compound attached to the surface of the LiNi oxide is not particularly limited, and a conventionally known Li compound can be used, but a compound having Li ion conductivity is preferable. . This is because a compound having Li ion conductivity has a low rate of increase in internal resistance even if it is scattered and coated as described later. On the other hand, in a compound that does not have Li ion conductivity, the coating (coating), the scattered and attached portions become resistances, and therefore, the decomposition of the electrolyte solution, which is the object of the present invention, is suppressed. Although swelling can be prevented, battery performance may be affected. Therefore, it can be said that a compound having Li ion conductivity is preferable in the present invention. Specific examples of the Li compound include lithium phosphate, LiPON compound, Li ₂ O—B ₂ O ₃ compound, Li ₂ O—B ₂ O ₃ —LiI compound, Li ₂ O—SiS ₂ compound, Li _2. Desirably, but at least one selected from the group consisting of S-SiS ₂ -Li ₃ PO ₄ compound, lithium cobaltate, lithium manganate, LiFePO ₄ and lithium hydroxide should be limited thereto is not. For example, in addition to the above, for example, lithium acetate, lithium acetylide ethylenediamine, lithium benzoate, lithium carbonate, lithium fluoride, lithium oxalate, lithium pyruvate, lithium stearate, lithium tartrate, lithium bromide, lithium iodide Li ₂ S—SiS ₂ compound, lithium nitrate, lithium sulfate, or the like can be used. These may be used alone or in combination of two or more. The composition of these Li compounds can be measured by, for example, ICP, atomic absorption method, fluorescent X-ray method, or particle analyzer.

As described above, the Li compound is preferably a compound having Li ion conductivity, and specifically has an ion conductivity of 10 ⁻¹⁵ S · m ⁻¹ or more, preferably 10 ⁻¹² S · m ⁻¹ or more. Things are desirable. The Li ion conductivity of such a Li compound can be measured, for example, by an AC impedance method, a constant potential step method, or a constant current step method.

  The Li compound may be attached to the surface of the LiNi oxide. For example, as shown in FIG. 1, the Li compound 13 may be attached so as to coat (coat) the surface of the LiNi oxide 11. As shown in FIG. 2, the Li compound 13 may be attached so as to be scattered on the surface of the LiNi oxide 11, but the present invention should not be limited to these. The LiNi oxide surface here refers to the surface of the LiNi oxide particles as shown in the figure. When the LiNi oxide is a secondary particle, the LiNi oxide particles are It may be the surface of the primary particles constituting the surface, or may be the surface of LiNi oxide particles (secondary particles) in which the primary particles are collected (aggregated or agglomerated). It may be the surface of both particles. That is, it can be said that the Li compound may be attached to at least one of the LiNi oxide particles (secondary particles) or the primary particles constituting the particles. 1 and FIG. 2 are examples of the surface of the LiNi oxide particles, it can be said that the LiNi oxide particles formed by collecting the primary particles are schematically represented as one particle. Note that the LiNi oxide (particle) 11 in the figure may be replaced with the primary particles constituting the LiNi oxide particles, so that the appearance of the Li compound attached to the primary particles can be seen as a schematic representation. it can.

  In addition, as an influence on the performance of the attachment due to the coating (coating) and the doting, first, it is shown that the coating (coating) is better with respect to the swelling of the battery (Table 1, Examples of Examples described later, (See 2 for comparison). This is thought to be because radical oxygen is not released into the electrolyte when the LiNi oxide (particle) surface is completely coated (coated) with the Li compound, while LiLi oxide (particle) surface is free of Li It is considered that radical oxygen is slightly emitted when the compound is scattered.

  In addition, among the influences on the performance due to the coating (coating) and the sprinkling, regarding the increase in internal resistance, it is shown that the sprinkling is better (contrast Tables 1 and 2 of the examples described later). See This is considered to be because when the surface of LiNi oxide (particles) is completely coated (coated) with a Li compound, there is no surface on which Li ions can react directly from the electrolytic solution, so the resistance becomes high. However, if there is no Li compound on the surface of the LiNi oxide (particle) as in the comparative example described later, not only the swelling of the battery can be suppressed, but the resistance increases due to the reaction between the LiNi oxide surface and the electrolyte. it is conceivable that.

  The method for attaching the Li compound to the surface of the lithium nickel oxide is not particularly limited, and a conventionally known attachment (coating, dotted) technique can be applied. Specifically, as a method for attaching, either a wet method or a dry method can be applied. Among these, as a wet method, for example, when LiNi oxide is produced by a coprecipitation method, a Li compound is mixed into a raw material before coprecipitation (a raw material of LiNi oxide that is a positive electrode material active material), and coprecipitation is performed. Then, it is thermally decomposed and baked to obtain a LiNi oxide surface with a Li compound attached thereto. On the other hand, as a dry method, for example, a Li compound is mixed in a positive electrode material active material produced by the above wet method without mixing a Li compound, and is dry mixed. Hybridization systems (Nara Machinery Co., Ltd.), Cosmos (Kawasaki Heavy Industries), Mechano-Fusion (Hosokawa Micron), Surfing System (Nihon Pneumatic Kogyo), MechanoMill / Speed Kneader / Speed Mill / Spiracoater Any known method and apparatus such as (Okada Seiko Co., Ltd.) can be applied. If necessary, then heat. As a result, it is possible to obtain a LiNi oxide surface with a Li compound attached thereto.

  The Li compound (coating layer) has a thickness in the range of 5 nm to 1 μm, preferably 50 nm to 1 μm, more preferably 70 to 700 nm. Such an embodiment is suitably applied when the Li compound 13 is attached so as to cover the surface of the LiNi oxide 11 mainly as shown in FIG. When the thickness of the Li compound (the coating layer) is less than 5 nm, it may be difficult to sufficiently suppress the generation of oxygen radicals from the LiNi oxide that is the object of the present invention, and the decomposition of the electrolyte solution May be difficult to prevent sufficiently. On the other hand, when the thickness of the Li compound (the coating layer) exceeds 1 μm, the resistance increases even though it has Li ion conductivity, which affects the high reactivity of the positive electrode active material. There is a risk. The thickness (of the coating layer) of the Li compound can be measured, for example, by TEM observation of the particle cross section.

  The Li compound is desirably in the range of 0.5 to 10, preferably 0.7 to 7, assuming that the volume of the positive electrode material active material is 100. Such an embodiment is mainly applied to the case where the Li compound 13 is attached so as to be scattered on the surface of the LiNi oxide 11 as shown in FIG. When the Li compound is less than 0.5 with respect to the positive electrode material active material volume 100, the Li compound that can be scattered on the surface of the LiNi oxide is limited. In some cases, it is difficult to sufficiently suppress the generation of oxygen radicals from a certain LiNi oxide, and it may be difficult to sufficiently prevent decomposition of the electrolytic solution. On the other hand, when the Li compound exceeds 10 with respect to the volume 100 of the positive electrode material active material, the Li compound will cover almost the entire surface of the LiNi oxide, making it difficult to intersperse, Since the amount of the Li compound not directly involved in the reaction increases, the high reactivity of the positive electrode active material may be affected even though it has Li ion conductivity. Here, the amount of the Li compound is based on the volume 100 of the positive electrode material active material, but from the viewpoint of preventing the generation of radical oxygen in the LiNi oxide that is the positive electrode material active material, the volume of the LiNi oxide is actually It can be said that it is more desirable to use 100 as a reference. That is, it can be said that the Li compound is more desirably in the range of 0.5 to 10, preferably 0.8 to 8, where the volume of the LiNi oxide is 100. The volume of the Li compound can be measured, for example, by SEM observation or TEM observation.

  In the positive electrode material for a non-aqueous electrolyte lithium ion battery according to the present invention, any material may be used as long as it contains a Li compound attached to a LiNI oxide surface. A positive electrode material can optionally be contained. These are not particularly limited, and conventionally known ones can be widely applied. These will be described below.

  Other positive electrode materials that can be used as a positive electrode material for a non-aqueous electrolyte lithium ion battery in the present invention include a conductive auxiliary agent for increasing electronic conductivity, a binder, and an electrolyte supporting salt for increasing ionic conductivity (lithium salt). ), Polymer gels or solid electrolytes (host polymers, electrolytes, etc.). In the case of using a polymer gel electrolyte for the battery electrolyte layer, it is sufficient that a conventionally known binder, a conductive auxiliary agent for enhancing electronic conductivity, etc. are contained. Lithium salt or the like may not be contained. Even when a solution electrolyte is used for the battery electrolyte layer, the positive electrode material may not contain a host polymer, an electrolytic solution, a lithium salt, or the like as a raw material of the polymer electrolyte.

  Examples of the conductive aid include acetylene black, carbon black, graphite, and vapor grown carbon fiber (VGCF). However, it is not necessarily limited to these.

  As the binder, polyvinylidene fluoride (PVDF), SBR, polyimide, or the like can be used. However, it is not necessarily limited to these.

  The polymer gel electrolyte includes a solid polymer electrolyte having ion conductivity and an electrolyte used in a conventionally known non-aqueous electrolyte lithium ion battery, and further has lithium ion conductivity. A structure in which a similar electrolyte solution is held in a non-polymeric skeleton is also included.

Here, the electrolytic solution (electrolyte supporting salt and plasticizer) contained in the polymer gel electrolyte is not particularly limited, and various conventionally known electrolytic solutions can be appropriately used. For example, inorganic acid anion salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiTaF ₆ , LiAlCl ₄ , Li ₂ B ₁₀ Cl ₁₀ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C 2 _F 5 _{SO 2)} selected from organic acid anion salts such as 2 _N, wherein at least one lithium salt (electrolyte support salt), propylene carbonate, cyclic carbonates such as ethylene carbonate; dimethyl carbonate , Chain carbonates such as methyl ethyl carbonate and diethyl carbonate; ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-dibutoxyethane; γ-butyrolactone, etc. Lactones; Nitto such as acetonitrile Lyls; Esters such as methyl propionate; Amides such as dimethylformamide; Plasticizers such as aprotic solvents (organic) mixed with at least one selected from methyl acetate and methyl formate Those using a solvent) can be used. However, it is not necessarily limited to these.

  Examples of the solid polymer electrolyte having ion conductivity include known solid polymer electrolytes such as polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof.

  For example, polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), etc. are used as the polymer having no lithium ion conductivity used in the polymer gel electrolyte. it can. However, it is not necessarily limited to these. Note that PAN, PMMA, etc. are in a class that has almost no ionic conductivity, and therefore can be a polymer having the above ionic conductivity, but here, they are used for a polymer gel electrolyte. This is exemplified as a polymer having no lithium ion conductivity.

As an electrolyte support salt to increase the ionic conductivity, for _{example, LiPF 6, LiBF 4, LiClO} 4, LiAsF 6, LiTaF 6, LiAlCl 4, Li 2 B 10 Cl 10 inorganic acid anion salts such as, Li ( An organic acid anion salt such as CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, or a mixture thereof can be used. However, it is not necessarily limited to these.

  The ratio (mass ratio) between the host polymer and the electrolytic solution in the polymer gel electrolyte may be determined according to the purpose of use, but is in the range of 2:98 to 90:10. That is, in the present invention, particularly from the viewpoint of suppressing the decomposition of the electrolytic solution due to the release of radical oxygen from the LiNi oxide, among nonaqueous electrolytes, a solution electrolyte or a polymer gel electrolyte that uses an electrolytic solution is particularly used. It works effectively against. Therefore, regarding the ratio (mass ratio) between the host polymer and the electrolytic solution in the polymer gel electrolyte, it is not necessary to limit the amount of the electrolytic solution for the purpose of preventing the swelling of the battery due to the decomposition of the electrolytic solution, and priority is given to the battery characteristics. It is something that can be done.

  In the positive electrode material of the present invention, a LiNi oxide with a Li compound added to the surface, a positive electrode material active material other than LiNi oxide, a conductive auxiliary agent, a binder, a polymer electrolyte (host polymer, electrolyte, etc.), lithium salt The blending amount should be determined in consideration of the intended use of the battery (emphasis on output, emphasis on energy, etc.) and ion conductivity.

  Next, the positive electrode material for a non-aqueous electrolyte lithium ion battery according to the present invention can be widely applied to a non-aqueous electrolyte lithium ion battery.

  That is, the battery to which the positive electrode material of the present invention can be applied is a non-aqueous electrolyte lithium ion battery using a LiNi oxide that can be expected to have a high capacity. In particular, high energy density and high output density can be achieved, and it can be suitably used as a drive power source for vehicles, etc., and can be sufficiently applied to non-aqueous electrolyte secondary batteries for portable devices such as mobile phones. Therefore, although the following description demonstrates the nonaqueous electrolyte lithium ion secondary battery using the positive electrode material of this invention, it should not be restrict | limited at all to these.

  That is, the non-aqueous electrolyte lithium ion battery that is the subject of the present invention may be any non-aqueous electrolyte lithium ion battery that uses the above-described positive electrode material of the present invention, and other constituent requirements should be limited in any way. is not. For example, when the above non-aqueous electrolyte lithium ion battery is distinguished by usage pattern, it can be applied to any usage pattern of a primary battery and a secondary battery. When the non-aqueous electrolyte lithium ion battery is distinguished by its form and structure, it can be applied to any conventionally known form and structure such as a stacked (flat) battery and a wound (cylindrical) battery. It is. Moreover, when viewed in terms of electrical connection form (electrode structure) in the non-aqueous electrolyte lithium ion battery, it is not a bipolar type (internal parallel connection type) battery or a bipolar type (internal series connection type) battery. Is also applicable. In the bipolar battery, a single cell voltage is higher than that of a normal battery, and a battery having excellent capacity and output characteristics can be configured. Since the polymer battery does not cause liquid leakage, it is advantageous in that a non-aqueous battery having no problem of liquid junction and having high reliability and excellent output characteristics can be formed with a simple configuration. In addition, by adopting a laminated (flat) battery structure, long-term reliability can be secured by a sealing technique such as simple thermocompression bonding, which is advantageous in terms of cost and workability.

  Therefore, in the following description, a non-bipolar non-aqueous electrolyte lithium ion secondary battery and a bipolar non-aqueous electrolyte lithium ion secondary battery using the positive electrode material of the present invention will be described briefly with reference to the drawings. It should never be limited to these. That is, there are no restrictions on the constituent elements other than the positive electrode material described above.

  FIG. 3 shows a schematic cross-sectional view of a flat (stacked) non-aqueous electrolyte lithium ion secondary battery that is not a bipolar type. In the lithium ion secondary battery 31 shown in FIG. 3, a positive electrode current collector is obtained by using a laminate film in which a polymer-metal composite is combined with a battery exterior material 32 and bonding all the peripheral portions thereof by heat fusion. A negative electrode active material layer 37 is formed on both surfaces of the positive electrode plate having the positive electrode active material layer 34 formed on both surfaces of the electrode 33, the electrolyte layer 35, and the negative electrode current collector 36 (one side for the lowermost layer and the uppermost layer of the power generation element). In addition, the power generation element 38 in which the negative electrode plates are stacked is housed and sealed. In addition, the positive electrode (terminal) lead 39 and the negative electrode (terminal) lead 40 that are electrically connected to the electrode plates (positive electrode plate and negative electrode plate) are connected to the positive electrode current collector 33 and the negative electrode current collector 36 of each electrode plate. It is attached by sonic welding, resistance welding, or the like, and has a structure that is sandwiched between the heat fusion parts and exposed to the outside of the battery outer packaging material 32.

  FIG. 4 is a schematic cross-sectional view schematically showing the entire structure of a bipolar nonaqueous electrolyte lithium ion secondary battery (hereinafter also simply referred to as a bipolar battery). As shown in FIG. 4, in the bipolar battery 41, a positive electrode active material layer 43 is provided on one side of a current collector 42 composed of one or more sheets, and the negative electrode active material layer of the present invention is provided on the other side. The positive electrode active material 43 and the negative electrode active material layer 44 of the bipolar electrode 45 adjacent to each other with the electrolyte layer 46 sandwiched between the bipolar electrode 45 provided with 44 are opposed to each other. That is, in the bipolar battery 41, a plurality of bipolar electrodes 45 having the positive electrode active material layer 43 on one surface of the current collector 42 and the negative electrode active material layer 44 on the other surface are disposed via the electrolyte layer 46. The electrode laminate (bipolar battery main body) 47 has a laminated structure. Further, the uppermost layer and the lowermost layer electrodes 45a and 45b of the electrode laminate 47 in which a plurality of such bipolar electrodes 45 and the like are laminated may not have a bipolar electrode structure, and are necessary for the current collector 42 (or terminal plate). A structure in which the positive electrode active material layer 43 or the negative electrode active material layer 44 only on one side may be arranged. In the bipolar battery 41, positive and negative electrode leads 48 and 49 are joined to current collectors 42 at both upper and lower ends, respectively.

  Note that the number of stacked bipolar electrodes 45 (including the electrodes 45a and 45b) is adjusted according to a desired voltage. Further, in the bipolar battery 41, the number of lamination of the bipolar electrode 45 may be reduced if a sufficient output can be secured even if the battery is made as thin as possible. Further, in the bipolar battery 41 of the present invention, in order to prevent external impact and environmental degradation during use, the electrode laminate 47 portion is sealed under reduced pressure in a battery exterior material (exterior package) 50, and electrode leads 48, It is preferable that 49 be taken out of the battery exterior material 50. The basic configuration of the bipolar battery 41 can be said to be a configuration in which a plurality of stacked single battery layers (single cells) are connected in series. This bipolar type non-aqueous electrolyte lithium ion secondary battery is basically the same as the non-bipolar type non-aqueous electrolyte lithium ion secondary battery described above except that its electrode structure is different. The elements are summarized below.

[Current collector]
The current collector that can be used in the present invention is not particularly limited, and conventionally known current collectors can be used. For example, aluminum foil, stainless steel (SUS) foil, nickel-aluminum clad material, copper-aluminum clad material, SUS-aluminum clad material, or a plated material of a combination of these metals can be preferably used. Further, a current collector in which a metal surface is coated with aluminum may be used. Moreover, you may use the electrical power collector which bonded 2 or more metal foil depending on the case. When the composite current collector is used, as a material for the positive electrode current collector, for example, a conductive metal such as aluminum, an aluminum alloy, SUS, or titanium can be used, and aluminum is particularly preferable. On the other hand, as the material of the negative electrode current collector, for example, conductive metals such as copper, nickel, silver, and SUS can be used, and SUS and nickel are particularly preferable. Further, in the composite current collector, the positive electrode current collector and the negative electrode current collector may be electrically connected to each other directly or via a conductive intermediate layer made of a third material. In addition to the flat plate (foil), the positive electrode current collector and the negative electrode current collector are constituted by a lath plate, that is, a plate in which a mesh space is formed by expanding a plate with a cut. Can also be used.

  Although the thickness of a collector is not specifically limited, Usually, it is about 1-100 micrometers.

[Positive electrode active material layer]
Here, the constituent material of the positive electrode active material layer is characterized in that the positive electrode material of the present invention is used, and since it has already been described, the description thereof is omitted here.

  The thickness of the positive electrode active material layer is not particularly limited, and should be determined in consideration of the purpose of use of the battery (output importance, energy importance, etc.) and ion conductivity. The thickness of a general positive electrode active material layer is about 1 to 500 μm, and if it is within this range, it can be sufficiently used in the present invention, but in order to effectively express the function of the positive electrode material of the present invention, In particular, the range of 4 to 60 μm is desirable.

[Negative electrode active material layer]
The negative electrode active material layer includes a negative electrode material active material. In addition to this, conductive aids to enhance electronic conductivity, binders, electrolyte supporting salts (lithium salts) to enhance ionic conductivity, polymer gels or solid electrolytes (host polymers, electrolytes, etc.), etc. Can be. Except for the type of the negative electrode active material, the content is basically the same as that described in the section “Positive electrode material for non-aqueous electrolyte lithium ion battery” of the present invention, and thus the description thereof is omitted here.

  As the negative electrode material active material, a negative electrode active material that is also used in a conventionally known solution-type lithium ion battery can be used. Specifically, a negative electrode mainly composed of at least one selected from carbon materials such as natural graphite, artificial graphite, amorphous carbon, coke and mesophase pitch carbon fiber, graphite, and hard carbon which is amorphous carbon. Although it is desirable to use an active material, it is not particularly limited. In addition, a metal oxide (particularly a transition metal oxide, specifically titanium oxide), a composite oxide of a metal (particularly a transition metal, specifically titanium) and lithium, or the like can also be used.

[Nonaqueous electrolyte layer]
The present invention can be applied to any of (a) a separator impregnated with an electrolytic solution, (b) a polymer gel electrolyte, and (c) a polymer solid electrolyte depending on the purpose of use.

(A) Separator soaked with electrolyte solution As an electrolyte solution that can be soaked into the separator, the electrolyte contained in the polymer gel electrolyte of the above-described "positive electrode material for non-aqueous electrolyte lithium ion battery" of the present invention Since the same liquid (electrolyte salt and plasticizer) can be used, description thereof is omitted here. However, if a suitable example of the electrolytic solution is shown, LiClO ₄ , LiAsF ₆ , LiPF ₆ can be used as the electrolyte. , LiBOB, LiCF ₃ SO ₃ and Li (CF ₃ SO ₂ ) ₂ , and the solvent is ethylene carbonate (EC), propylene carbonate, diethyl carbonate (DEC), dimethyl carbonate, methyl ethyl carbonate, 1, 2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran The concentration of the electrolyte is adjusted to 0.5 to 2 mol / liter by dissolving at least one of ethers composed of 1,3-dioxolane and γ-butyllactone and dissolving the electrolyte in the solvent. However, the present invention should not be limited to these.

  The separator is not particularly limited, and a conventionally known separator can be used. For example, a porous sheet made of a polymer that absorbs and holds the electrolytic solution (for example, a polyolefin microporous material). Separator, etc.), a nonwoven fabric separator, etc. can be used. The polyolefin microporous separator having the property of being chemically stable to an organic solvent has an excellent effect that the reactivity with the electrolyte (electrolytic solution) can be kept low.

  Examples of the material for the porous sheet such as the polyolefin-based microporous separator include a laminate having a three-layer structure of polyethylene (PE), polypropylene (PP), PP / PE / PP, and polyimide.

  As the material of the nonwoven fabric separator, for example, conventionally known materials such as cotton, rayon, acetate, nylon, polyester, polypropylene, polyethylene and other polyolefins, polyimide, and aramid can be used, and the purpose of use (machines required for the electrolyte layer) Depending on strength, etc., they are 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. That is, if the bulk density of the nonwoven fabric is too large, the proportion of the non-electrolyte material in the electrolyte layer becomes too large, which may impair the ionic conductivity in the electrolyte layer.

  The thickness of the separator (including the non-woven separator) cannot be unambiguously defined because it varies depending on the usage, but it can be used for motor-driven secondary batteries such as electric vehicles (EV) and hybrid electric vehicles (HEV). In use, it is desirable to be 5 to 200 μm. When the thickness of the separator is within such a range, it is possible to suppress increase in retention and resistance. In addition, there is an effect of securing mechanical strength in the thickness direction and ensuring high output performance because it is desirable to prevent a short circuit caused by fine particles entering the separator and to narrow the space between the electrodes for high output. . In addition, when a plurality of batteries are connected, the electrode area increases, so that it is desirable to use a thick separator in the above range in order to increase the reliability of the battery.

  It is desirable that the fine pore diameter of the separator (polyolefin-based microporous separator or the like) is 1 μm or less (usually a pore diameter of about several tens of nm). Due to the fact that the average diameter of the micropores in the separator is within the above range, the “shutdown phenomenon” that the separator melts due to heat and the micropores close quickly occurs, resulting in higher reliability during abnormalities, resulting in heat resistance. Has the effect of improving. In other words, when the battery temperature rises due to overcharging (in an abnormal state), the “shutdown phenomenon” that the separator melts and closes the micropores occurs quickly, so that the positive electrode (+) of the battery (electrode) Li ions cannot pass through to the negative electrode (−) side, and no further charge is possible. As a result, overcharging cannot be performed and overcharging is eliminated. As a result, the heat resistance (safety) of the battery is improved, and it is possible to prevent gas from being released and the heat fusion part (seal part) of the battery exterior material from being opened. Here, the average diameter of the micropores of the separator is calculated as an average diameter obtained by observing the separator with a scanning electron microscope or the like and statistically processing the photograph with an image analyzer or the like.

  The porosity of the separator (such as a polyolefin microporous separator) is desirably 20 to 50%. The separator's porosity is within the above range, preventing output from being reduced due to the resistance of the electrolyte (electrolyte), and preventing the short circuit caused by fine particles penetrating the separator's pores (micropores). It has the effect of securing both sexes. Here, the porosity of the separator is a value obtained as a volume ratio from the density of the raw material resin and the density of the separator of the final product.

  The porosity of the nonwoven fabric separator is preferably 50 to 90%. If the porosity is less than 50%, the electrolyte retention deteriorates, and if it exceeds 90%, the strength is insufficient.

  The amount of the electrolytic solution impregnated in the separator may be impregnated to the range of the liquid retention capacity of the separator, but may be impregnated beyond the liquid retention capacity range. This can prevent impregnation of the electrolyte from the electrolyte layer by injecting a resin into the electrolyte seal portion, and therefore can be impregnated as long as the electrolyte layer can be retained. The electrolyte can be impregnated in the separator by a conventionally known method, for example, the electrolyte can be completely sealed after being injected by a vacuum injection method or the like.

(B) Polymer gel electrolyte and (c) Polymer solid electrolyte As the polymer gel electrolyte and polymer solid electrolyte, the polymer gel described in the section “Positive electrode material for non-aqueous electrolyte lithium ion battery” of the present invention described above is used. Since the same electrolyte and polymer solid electrolyte can be used, description thereof is omitted here.

  The electrolyte layers (a) to (c) may be used in one battery.

  In addition, the polymer electrolyte may be included in the polymer gel electrolyte layer, the positive electrode active material layer, and the negative electrode active material layer, but the same polymer electrolyte may be used, or different polymer electrolytes may be used depending on the layer. Good.

  By the way, a host polymer for a polymer gel electrolyte that is preferably used at present is a polyether polymer such as PEO and PPO. For this reason, the oxidation resistance on the positive electrode side under high temperature conditions is weak. Therefore, when using a positive electrode material having a high oxidation-reduction potential, the capacity of the negative electrode (active material layer) is preferably smaller than the capacity of the positive electrode (active material layer) opposed via the polymer gel electrolyte layer. When the capacity of the negative electrode (active material layer) is less than the capacity of the opposing positive electrode (active material layer), it is possible to prevent the positive electrode potential from rising excessively at the end of charging. In addition, the capacity | capacitance of a positive electrode (active material layer) and a negative electrode (active material layer) can be calculated | required from manufacturing conditions as theoretical capacity | capacitance at the time of manufacturing a positive electrode (active material layer) and a negative electrode (active material layer). You may measure the capacity | capacitance of a finished product directly with a measuring device. However, if the capacity of the negative electrode (active material layer) is smaller than the capacity of the opposing positive electrode (active material layer), the negative electrode potential will drop too much and the durability of the battery may be impaired. There is a need. For example, care should be taken not to lower the durability by setting the average charge voltage of one cell (single cell layer) to an appropriate value for the oxidation-reduction potential of the positive electrode active material.

  The thickness of the electrolyte layer constituting the battery is not particularly limited. However, in order to obtain a compact battery, it is preferable to make it as thin as possible within a range in which the function as an electrolyte can be ensured, and the thickness of the electrolyte layer is preferably 5 to 200 μm.

[Insulation layer]
The insulating layer is mainly used in the case of a bipolar battery. This insulating layer is formed around each electrode for the purpose of preventing adjacent collectors in the battery from contacting each other and short-circuiting due to slight unevenness at the end of the laminated electrode. It is. In this invention, you may provide an insulating layer around an electrode as needed. When this is used as a vehicle driving or auxiliary power source, it is necessary to completely prevent a short circuit (liquid drop) due to the electrolytic solution. Furthermore, vibrations and impacts on the battery are loaded for a long time. Therefore, from the viewpoint of prolonging battery life, it is desirable to install an insulating layer in order to ensure longer-term reliability and safety, and to provide a high-quality, large-capacity power supply. .

  As the insulating layer, any insulating layer may be used as long as it has insulating properties, sealing performance against falling off of the solid electrolyte, sealing performance against moisture permeation from the outside (sealing performance), heat resistance under battery operating temperature, etc. Epoxy resin, rubber, polyethylene, polypropylene, polyimide and the like can be used, but epoxy resin is preferable from the viewpoint of corrosion resistance, chemical resistance, ease of production (film forming property), economy and the like.

[Positive electrode and negative electrode terminal plate]
The positive electrode and the negative electrode terminal plate may be used as necessary. For example, in the case of a bipolar lithium ion battery, depending on the laminated (or wound) structure, the electrode terminal may be directly taken out from the outermost current collector. In this case, the positive electrode and the negative electrode terminal plate are not used. It is also good (see FIG. 4).

  When using positive and negative terminal plates, in addition to having a function as a terminal, it is better to be as thin as possible from the viewpoint of thinning, but the laminated electrode, electrolyte and current collector all have mechanical strength. Since it is weak, it is desirable to have strength to sandwich and support these from both sides. Furthermore, it can be said that the thickness of the positive electrode and the negative electrode terminal plate is usually preferably about 0.1 to 2 mm from the viewpoint of suppressing the internal resistance at the terminal portion.

  As materials for the positive electrode and the negative electrode terminal plate, materials used in a conventionally known lithium ion battery can be used. For example, aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof can be used. Aluminum is preferably used from the viewpoints of corrosion resistance, ease of production, economy, and the like.

  The material of the positive electrode terminal plate and the negative electrode terminal plate may be the same material or different materials. Furthermore, the positive electrode and the negative electrode terminal plate may be a laminate of different materials.

[Positive electrode and negative electrode lead]
Regarding the positive electrode and the negative electrode lead, not only the bipolar type but also the same type of lead used in a conventionally known lithium ion battery that is not bipolar type can be used. In addition, the part taken out from the battery exterior material (battery case) does not affect the product (for example, automobile parts, especially electronic devices, etc.) by contacting with peripheral devices or wiring and leaking electricity. It is preferable to coat with a heat-resistant insulating heat-shrinkable tube or the like.

[Battery exterior material (battery case)]
Lithium-ion batteries, not limited to bipolar type, contain the entire battery stack or battery winding body, which is the battery body, in a battery case or battery case in order to prevent external impact and environmental degradation during use. It is desirable to do. From the viewpoint of weight reduction, a polymer-metal composite laminate film in which both surfaces of metals (including alloys) such as aluminum, stainless steel, nickel, and copper are covered with an insulator (preferably a heat-resistant insulator) such as a polypropylene film. It is preferable that the battery stack is housed and sealed by joining a part or all of the peripheral part thereof by heat fusion using a conventionally known battery exterior material. In this case, the positive electrode and the negative electrode lead may be structured to be sandwiched between the heat-sealed portions and exposed to the outside of the battery exterior material. In addition, it is preferable to use a polymer-metal composite laminate film having excellent thermal conductivity because heat can be efficiently transmitted from a heat source of an automobile and the inside of the battery can be quickly heated to the battery operating temperature. The polymer-metal composite laminate film is not particularly limited, and a conventionally known film in which a metal film is disposed between polymer films and the whole is laminated and integrated can be used. As specific examples, for example, an outer protective layer made of a polymer film (laminate outermost layer), a metal film layer, a heat-sealing layer made of a polymer film (laminate innermost layer), and the whole is laminated and integrated. The thing which becomes. Specifically, in the polymer-metal composite laminate film used for the exterior material, a heat-resistant insulating resin film is first formed as a polymer film on both surfaces of the metal film, and heat fusion is performed on at least one heat-resistant insulating resin film. An insulating insulating film is laminated. Such a laminate film is heat-sealed by an appropriate method, whereby the heat-welding insulating film portion is fused and joined to form a heat-sealing portion. An example of the metal film is an aluminum film. Moreover, as said insulating resin film, a polyethylene tetraphthalate film (heat-resistant insulating film), a nylon film (heat-resistant insulating film), a polyethylene film (heat-bonding insulating film), a polypropylene film (heat-bonding insulating film) ) Etc. can be illustrated. However, the exterior material of the present invention should not be limited to these. In such a laminate film, it is possible to easily and surely join one to one (bag-like) laminate films by heat fusion using a heat fusion insulating film by ultrasonic welding or the like. In order to maximize the long-term reliability of the battery, metal films that are constituent elements of the laminate sheet may be directly joined. Ultrasonic welding can be used to join the metal films by removing or destroying the heat-fusible resin between the metal films.

  Next, as a use of the non-aqueous electrolyte lithium ion secondary battery of the present invention, for example, as a large-capacity power source for an electric vehicle (EV), a hybrid electric vehicle (HEV), a fuel cell vehicle, a hybrid fuel cell vehicle, etc. It can be suitably used for a vehicle driving power source and an auxiliary power source that require energy density and high output density. In this case, it is desirable that the assembled battery is constructed by connecting a plurality of the nonaqueous electrolyte lithium ion batteries of the present invention. That is, in the present invention, an assembled battery (vehicle sub-module) is formed using at least one of the plurality of nonaqueous electrolyte lithium ion secondary devices in parallel connection, series connection, parallel-series connection, or series-parallel connection. be able to. This makes it possible to meet the demands for capacity and voltage for various types of vehicles by combining basic batteries. As a result, it becomes possible to facilitate the design selectivity of required energy and output. For this reason, it is not necessary to design and produce different batteries for various vehicles, and it becomes possible to mass-produce basic batteries and to reduce costs by mass production. Hereinafter, a representative embodiment of the assembled battery (vehicle submodule) will be briefly described with reference to the drawings.

  FIG. 5 shows a schematic diagram of an assembled battery (42V1Ah) in which the bipolar battery (24V, 50 mAh) of the present invention is connected in two lines and 20 lines. The tabs in the parallel part were connected by copper bus bars 56 and 58, and the serial part was connected by vibration welding the tabs 48 and 49 together. The ends of the series part are connected to the terminals 62 and 64 to constitute positive and negative terminals. On both sides of the battery, detection tabs 60 for detecting the voltage of each layer of the bipolar battery 41 are taken out, and their detection lines 53 are taken out to the front part of the assembled battery 51. Specifically, in order to form the assembled battery 51 shown in FIG. 5, five bipolar batteries 41 are connected in parallel by a bus bar 56, and two bipolar batteries 41 connected in parallel are connected to each other by electrode tabs in series. These are stacked in four layers and connected in parallel by a bus bar 58 and housed in a metal assembled battery case 55. In this way, by connecting an arbitrary number of bipolar batteries 41 in series and parallel, an assembled battery 51 that can handle a desired current, voltage, and capacity can be provided. In the assembled battery 51, a positive electrode terminal 62 and a negative electrode terminal 64 are formed at the front side of the metal assembled battery case 55. After connecting the batteries in series and parallel, for example, each bus bar 56 and each positive electrode terminal 62. The negative terminal 64 is connected to the terminal lead 59. Further, the assembled battery 51 includes a positive electrode terminal 62 and a negative electrode terminal of a metal assembled battery case 55 for detecting the battery voltage (each cell layer, and further the voltage between terminals of the bipolar battery). 64 is installed at the front of the side surface. All the voltage detection tabs 60 of each bipolar battery 41 are connected to the detection tab terminal 54 via the detection line 53. In addition, an external elastic body 52 is attached to the bottom of the assembled battery case 55, and when a plurality of assembled batteries 51 are stacked to form a composite assembled battery, the distance between the assembled batteries 51 is maintained to prevent vibration. , Impact resistance, insulation, heat dissipation, etc. can be improved.

  In addition to the detection tab terminal 54, the assembled battery 51 may be provided with various measuring devices and control devices depending on the usage. Furthermore, in order to connect the electrode tabs (48, 49) of the bipolar battery 1 or the detection tab 60 and the detection line 53, ultrasonic welding, heat welding, laser welding, electron beam welding, or a rivet is used. You may make it connect using the bus-bars 56 and 58, or using the crimping method. Furthermore, in order to connect the bus bars 56, 58 and the terminal leads 59, etc., ultrasonic welding, heat welding, laser welding, or electron beam welding may be used.

  The external elastic body 52 may be made of the same material as that of the resin group used in the battery of the present invention, but is not limited thereto.

  In the assembled battery of the present invention, the bipolar non-aqueous electrolyte lithium ion battery (hereinafter also simply referred to as a bipolar battery) of the present invention has the same positive and negative electrode material as the bipolar battery, and the number of structural units of the bipolar battery. A non-aqueous electrolyte lithium ion secondary battery of the present invention (hereinafter also referred to simply as a non-bipolar battery) having the same voltage by serially connecting them in parallel may be used. That is, the battery forming the assembled battery may be a mixture of a bipolar battery of the present invention and a battery that is not a bipolar type (however, not all batteries need to be batteries of the present invention). As a result, an assembled battery that compensates for each other's weaknesses by combining a bipolar battery that focuses on output and a non-bipolar battery that focuses on energy can be achieved, and the weight and size of the assembled battery can be reduced. The proportion of each bipolar battery and non-bipolar battery to be mixed is determined according to the safety performance and output performance required for the assembled battery.

  FIG. 6 shows an assembled battery in which a bipolar battery A (42 V, 50 mAh) and a non-bipolar battery B (4.2 V, 1 Ah) 10 series (42 V) are connected in parallel. The non-bipolar battery B and the bipolar battery A have the same voltage and form a parallel connection at that portion. The assembled battery 51 ′ has a structure in which the bipolar battery A has an output sharing and the non-bipolar battery B has an energy sharing. This is a very effective means in an assembled battery in which it is difficult to achieve both output and energy. In this assembled battery 51 ′, the tabs of the parallel portion and the portion that is connected in series between the non-bipolar type batteries B adjacent in the horizontal direction in the figure are connected by the copper bus bar 56, and between the general batteries B adjacent in the vertical direction in the figure. The portions connected in series were connected by vibration welding the tabs 39 and 40 together. The ends of the portion where the non-bipolar battery B and the bipolar battery A are connected in parallel are connected to the terminals 62 and 64 to constitute positive and negative terminals. 5 except that the detection tab 60 for detecting the voltage of each layer of the bipolar battery A is taken out on both sides of the bipolar battery A, and the detection lines (not shown) are taken out at the front part of the assembled battery 51 ′. Therefore, the same members are denoted by the same reference numerals. Specifically, in order to form the assembled battery 51 ′ shown in FIG. 6, 10 non-bipolar type batteries B were sequentially welded in series from the end and connected in series. Further, the bipolar battery A and the non-bipolar battery B at both ends connected in series are connected in parallel by the bus bar 56 and accommodated in a metal assembled battery case 55. In this way, by connecting an arbitrary number of bipolar batteries A in series and parallel, an assembled battery 51 ′ that can handle a desired current, voltage, and capacity can be provided. The assembled battery 50 ′ also has a positive electrode terminal 62 and a negative electrode terminal 64 formed on the front side of the metal assembled battery case 55. After connecting the batteries A and B in series and parallel, for example, Each positive terminal 62 and negative terminal 64 are connected by a terminal lead 59. Further, the assembled battery 51 'has a detection tab terminal 54 made of metal for monitoring battery voltage (voltage of each single battery layer of the bipolar battery A, and voltage between terminals of the bipolar battery A and the non-bipolar battery B). The assembled battery case 55 is installed at the front side of the side surface where the positive electrode terminal 62 and the negative electrode terminal 64 are provided. And all the detection tabs 60 of each bipolar battery A (and non-bipolar type battery B) are connected to the detection tab terminal 54 via a detection line (not shown). In addition, an external elastic body 52 is attached to the lower part of the assembled battery case 55, and when a composite assembled battery is formed by stacking a plurality of assembled batteries 51 ′, the distance between the assembled batteries 51 ′ is maintained. In addition, vibration resistance, impact resistance, insulation, heat dissipation, and the like can be improved.

  In the assembled battery of the present invention, the above-mentioned bipolar battery is further connected in series and parallel to form a first assembled battery unit, and the voltage between the terminals of the first assembled battery unit is the same as that of the other two batteries other than the bipolar battery. There is no particular limitation such as forming a second assembled battery unit in which the secondary batteries are connected in series and parallel, and connecting the first assembled battery unit and the second assembled battery unit in parallel. .

  The other constituent requirements of the assembled battery are not limited at all, and the same constituent requirements as the assembled battery using the existing non-bipolar lithium ion secondary battery can be applied as appropriate. However, since the conventionally known constituent members and manufacturing techniques for assembled batteries can be used, the description thereof is omitted here.

  Next, at least two or more of the above-mentioned assembled batteries (vehicle submodules) are combined in series, parallel, or in series and parallel to form a combined battery (vehicle assembled battery). It is possible to meet the demand for output relatively inexpensively without producing a new assembled battery. That is, the composite assembled battery of the present invention comprises at least two or more assembled batteries (such as those composed only of the bipolar battery or non-bipolar battery of the present invention, or composed of the bipolar battery of the present invention and a non-bipolar battery). It is characterized in that it is connected in series, in parallel, or in series and parallel, and the specification of the assembled battery can be tuned by manufacturing a standard assembled battery and combining it into a composite assembled battery. Thereby, since it is not necessary to manufacture many assembled battery types with different specifications, the composite assembled battery cost can be reduced.

  As a composite assembled battery, for example, FIG. 7 is a schematic diagram of a composite assembled battery (42V, 6Ah) connected in parallel with an assembled battery (42V, 1Ah) 6 using the bipolar battery shown in FIG. Each assembled battery constituting the composite assembled battery is integrated by a connecting plate and a fixing screw, and an anti-vibration structure is formed by installing an elastic body between the assembled batteries. The tabs of the assembled battery are connected by a plate-like bus bar. That is, as shown in FIG. 7, in order to connect the six assembled batteries 51 in parallel to form the composite assembled battery 70, the tabs of the assembled batteries 51 provided on the lid of each assembled battery case 55 ( The positive electrode terminal 62 and the negative electrode terminal 64) are electrically connected using an external positive electrode terminal portion that is a plate-shaped bus bar, an assembled battery positive electrode terminal connecting plate 72 having an external negative electrode terminal portion, and an assembled battery negative electrode terminal connecting plate 74, respectively. To do. Further, a connecting plate 76 having an opening corresponding to the fixing screw hole is fixed to each screw hole (not shown) provided on both side surfaces of each assembled battery case 55 with a fixing screw 77, and The batteries 51 are connected to each other. Moreover, the positive electrode terminal 62 and the negative electrode terminal 64 of each assembled battery 51 are protected by a positive electrode and a negative electrode insulating cover, respectively, and are identified by color-coding into appropriate colors, for example, red and blue. Further, an anti-vibration structure is formed by installing an external elastic body 52 between the assembled batteries 51, specifically, at the bottom of the assembled battery case 55.

  Moreover, in the said composite assembled battery, it is desirable to connect the some assembled battery which comprises this so that attachment or detachment is possible respectively. As described above, in the composite assembled battery in which a plurality of assembled batteries are connected in series and parallel, even if some of the batteries and the assembled battery fail, the repair can be performed only by replacing the failed part.

  The vehicle according to the present invention is characterized in that the assembled battery and / or the composite assembled battery is mounted. This makes it possible to meet a large vehicle demand for space by using a light and small battery. By reducing the battery space, the weight of the vehicle can be reduced.

  As shown in FIG. 8, in order to mount the composite battery pack 70 on a vehicle (for example, an electric vehicle or the like), the composite assembled battery 70 is mounted under a seat (seat) in the center of the vehicle body of the electric vehicle 80. This is because if it is installed under the seat, the interior space and the trunk room can be widened. The place where the battery is mounted is not limited to under the seat, but may be under the floor of the vehicle, behind the seat back, under the rear trunk room, or in the engine room in front of the vehicle.

  In the present invention, not only the composite battery pack but also the battery pack may be mounted on the vehicle depending on the intended use, or the composite battery pack and the battery pack may be mounted in combination. Further, as the vehicle on which the composite assembled battery or the assembled battery of the present invention can be mounted as a driving power source or an auxiliary power source, the above-described electric vehicle, fuel cell vehicle and hybrid vehicle thereof are preferable, but are not limited thereto. It is not a thing. In addition, as a vehicle on which the assembled battery and / or the composite assembled battery of the present invention can be mounted as, for example, a driving power source or an auxiliary power source, an electric vehicle, a hybrid electric vehicle, a fuel cell vehicle, a hybrid fuel cell vehicle, etc. However, it is not limited to these.

Hereinafter, the content of the present invention will be described with reference to examples and comparative examples, but the present invention is not limited to these examples.

Examples 1-42, 85, 86 and Comparative Examples 1-2
1. Production of Positive Electrode The LiNi oxide (average particle size 8 μm) shown in Table 1 was coated with the Li compound shown in Table 1 so as to have a thickness of 500 nm (Examples 1 to 42, 85). 86) to 75% by mass of LiNi oxides (average particle size 8 μm) shown in Table 1 (Comparative Examples 1 and 2; no Li compound added), 10% by mass of acetylene black as a conductive assistant, A slurry was prepared by adding N-methyl-2-pyrrolidone (NMP) as a solvent in a proportion of 15% by mass of vinylidene chloride, and stirring the slurry, and applying this to an applicator on an aluminum foil (thickness 20 μm) of the positive electrode current collector Then, the electrode was punched to a diameter of 15 mm and dried at 90 ° C. in a high vacuum for 6 hours. The thickness of the punched positive electrode active material layer was 50 μm. In addition, the method of coating (coating) the Li compound on the LiNi oxide was prepared using mechanofusion so that the coating thickness was 500 nm.

2. Production of Negative Electrode As a negative electrode active material powder, 85% by mass of carbon as a carbon-based material, 8% by mass of acetylene black as a conductive additive, 2% by mass of vapor grown carbon fiber (VGCF), and 5% by mass of polyvinylidene fluoride as a binder %, N-methyl-2-pyrrolidone (NMP) as a solvent is added and stirred to prepare a slurry, which is applied onto a copper foil (thickness 20 μm) of a negative electrode current collector with an applicator, and vacuum After heat drying at about 80 ° C. with a drier, the electrode was punched to a diameter of 16 mm and dried at 90 ° C. in a high vacuum for 6 hours. The thickness of the punched negative electrode (negative electrode active material layer) was 80 μm.

3. Production and Evaluation of Battery Each battery (coin cell) was configured using the positive electrode (Examples 1-42, 85, 86 and Comparative Examples 1-2) and the negative electrode (all the same) produced above. Specifically, a polypropylene (PP) microporous separator (average pore diameter of 800 nm, porosity of 35%, thickness of 30 μm) was used as the separator, and 1.0 M LiPF ₆ EC + DEC was used as the non-aqueous electrolyte. A coin cell was assembled using the solution. The capacity balance between the positive and negative electrodes was controlled by the positive electrode.

  Immediately after cell preparation, it was charged to 4.1 V at 0.2 C in terms of positive electrode and stored at room temperature for 1 week. Thereafter, the internal resistance was determined by direct current and stored at 4.1 V, 60 ° C. for one month, and then the internal resistance was determined by direct current in the same manner as in the initial stage. Moreover, the swelling (maximum swelling) of the battery was also measured. The obtained results are shown in Table 1.

Examples 43-84, 87, 88 and Comparative Examples 3-4
The LiNi oxide (average particle size 8 μm) shown in Table 1 was coated with the Li compound shown in Table 1 so as to have a thickness of 500 nm (Examples 1 to 42, 85, 86). Or instead of the LiNi oxide (average particle size 8 μm) shown in Table 1 (Comparative Examples 1 and 2; without Li compound attachment), the surface of LiNi oxide (average particle size 8 μm) shown in Table 2 is shown in Table 2. Li compounds dispersed and attached so as to be 1 with respect to the volume of LiNi oxide 100 (Examples 43 to 84, 87, 88) to LiNi oxides shown in Table 2 (average particle size 8 μm) A positive electrode, a negative electrode, and a battery were prepared and evaluated in the same manner as in Example 1 except that (Comparative Examples 3 to 4; Li compound not attached) was used. The obtained results are shown in Table 2.

  From the results shown in Tables 1 and 2 above, in each of the examples in which the LiNi oxide surface was added with a Li compound as the positive electrode material, the LiNi oxide surface was not attached with the Li compound. It was confirmed that the swelling of the battery can be suppressed as compared with the comparative example. Furthermore, regarding the battery performance, it was confirmed that the rate of increase in internal resistance after storage can be suppressed to be equal to or less than that of the comparative example. Therefore, when the voltage is high (charged state) and high temperature (60 ° C or higher), specifically, when used in a car, especially when placed near the engine room or motor, it was placed in an environment of about 60 ° C. It was found that the battery functions sufficiently even in charging and discharging in such a case. That is, it has been found that even when the voltage is high (charged) and the temperature is high, the reaction proceeds spontaneously and functions effectively without problems such as gas generation and an increase in internal resistance.

11 LiNi oxide,
13 Li compound,
31 A non-aqueous electrolyte lithium ion secondary battery that is not bipolar,
32 Battery exterior material,
33 positive electrode current collector,
34 positive electrode active material layer,
35 electrolyte layer,
36 negative electrode current collector,
37 negative electrode active material layer,
38 Power generation elements,
39 Positive electrode (terminal) lead,
40 Negative electrode (terminal) lead,
41 Bipolar non-aqueous electrolyte lithium ion secondary battery (bipolar battery),
42 current collector,
43 positive electrode active material layer,
44 negative electrode active material layer,
45 bipolar electrodes,
45a, the uppermost electrode of the electrode stack,
45b, the bottom electrode of the electrode stack,
46 electrolyte layer,
47 electrode laminate (bipolar battery body),
48 positive lead,
49 Negative lead,
50 Battery exterior material (exterior package),
51, 51 'battery pack,
52 external elastic body,
53 detection lines,
54 detection tab terminal,
55 battery pack case,
56, 58 Busbar,
59 Terminal lead,
62 positive terminal,
64 negative terminal,
70 composite battery pack,
72 composite battery positive electrode terminal connecting plate,
74 composite battery negative electrode terminal plate,
76 connecting plate,
77 fixing screws,
80 electric car,
91 particles (including irregular particles)
L Maximum length.

Claims (5)

A positive electrode material for a non-aqueous electrolyte lithium ion battery comprising a lithium nickel oxide surface coated with a Li compound and attached thereto,
The Li compound is lithium phosphate, LiPON compound, Li ₂ O—B ₂ O ₃ compound, Li ₂ O—B ₂ O ₃ —LiI compound, Li ₂ S—SiS ₂ compound, Li ₂ S—SiS ₂ —Li. ₃ PO ₄ compounds, lithium hydroxide, lithium fluoride, lithium acetate, lithium acetylide ethylenediamine, lithium benzoate, lithium bromide, lithium carbonate, lithium nitrate, lithium oxalate, lithium pyruvate, lithium stearate, lithium tartrate and sulfuric acid A positive electrode material for a non-aqueous electrolyte lithium ion battery, which is at least one selected from the group consisting of lithium.   2. The positive electrode material for a non-aqueous electrolyte lithium ion battery according to claim 1, wherein the Li compound has a thickness in a range of 50 nm to 1 μm. The Li compound is lithium phosphate, LiPON compound, Li ₂ O—B ₂ O ₃ compound, Li ₂ O—B ₂ O ₃ —LiI compound, Li ₂ S—SiS ₂ compound, Li ₂ S—SiS ₂ —Li. _{3. The} positive electrode material for a non-aqueous electrolyte lithium ion battery according to claim 1, wherein the positive electrode material is at least one selected from the group consisting of ₃ PO ₄ compounds, lithium hydroxide, and lithium fluoride.   A non-aqueous electrolyte lithium ion battery comprising the positive electrode material according to claim 1. Lithium compound is mixed in the positive electrode material active material, and dry-mixed using at least one device of hybridization system, cosmos, mechanofusion, surfing system and mechanomill speed kneader speed mill spira coater A method for producing a positive electrode material for a non-aqueous electrolyte lithium ion battery comprising a lithium nickel oxide surface coated with a Li compound and attached thereto,
The Li compound is lithium phosphate, LiPON compound, Li ₂ O—B ₂ O ₃ compound, Li ₂ O—B ₂ O ₃ —LiI compound, Li ₂ S—SiS ₂ compound, Li ₂ S—SiS ₂ —Li. ₃ PO ₄ compounds, lithium hydroxide, lithium fluoride, lithium acetate, lithium acetylide ethylenediamine, lithium benzoate, lithium bromide, lithium carbonate, lithium nitrate, lithium oxalate, lithium pyruvate, lithium stearate, lithium tartrate and sulfuric acid The manufacturing method of the positive electrode material for nonaqueous electrolyte lithium ion batteries which is at least 1 sort (s) chosen from the group which consists of lithium.