JP2021136188A - Nonaqueous electrolyte battery and battery pack - Google Patents

Abstract

To provide a nonaqueous electrolyte battery superior in charge-discharge cycle life, and a battery pack having the nonaqueous electrolyte battery.SOLUTION: A nonaqueous electrolyte battery which comprises a positive electrode 3, a negative electrode 2 containing a lithium titanium-containing oxide, and a nonaqueous electrolyte and satisfies the expression (1) is provided according to an embodiment hereof. The positive electrode 3 contains a positive electrode active material including a lithium-containing manganese oxide, and a lithium-containing nickel cobalt manganese oxide. In the positive electrode active material, the content of the lithium-containing nickel cobalt manganese oxide is 3 wt% or more and 20 wt% or less. 0.005≤(GCo/SCo)/(GTi/STi)≤0.15 (1), where GCo is a weight (mg) of Co included in a positive electrode active material-containing layer 3b, SCo is an area (cm2) of the positive electrode active material-containing layer 3b, GTi is a weight (mg) of Ti included in a negative electrode active material-containing layer 2b, and STi is an area (cm2) of the negative electrode active material-containing layer 2b.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to non-aqueous electrolyte batteries and battery packs.

Secondary batteries, including lithium-ion secondary batteries, are widely used in vehicles such as mobile devices and automobiles, and storage batteries. Secondary batteries are power storage devices whose market size is expected to expand.

The secondary battery includes electrodes including a positive electrode and a negative electrode. The secondary battery may further contain an electrolyte. The electrodes of a secondary battery of a certain design include a current collector and an active material-containing layer provided on the main surface of the current collector. The active material-containing layer of the electrode can be, for example, a layer composed of active material particles, a conductive agent, and a binder, and can be a porous body capable of retaining an electrolyte.

An example of an active material used for the positive electrode of a lithium ion battery or a secondary battery is a lithium-containing manganese oxide. A lithium ion secondary battery using lithium-containing manganese oxide for the positive electrode and lithium titanate for the negative electrode has excellent low-temperature output and longevity performance.

International Publication No. 2016/132436 International Publication No. 2016/143123

An object of the present invention is to provide a non-aqueous electrolyte battery having an excellent charge / discharge cycle life, and a battery pack including the battery.

According to the embodiment, a non-aqueous electrolyte battery containing a positive electrode, a negative electrode including a negative electrode active material-containing layer containing a lithium titanium-containing oxide, and a non-aqueous electrolyte, and satisfying the following equation (1) is provided. NS. The positive electrode includes a positive electrode active material-containing layer containing a positive electrode active material containing a lithium-containing manganese oxide and a lithium-containing nickel cobalt manganese oxide. The content of lithium-containing nickel-cobalt-manganese oxide in the positive electrode active material is 3 wt% or more and 20 wt% or less.
0.005 ≤ (G _Co / S _Co ) / (G _Ti / S _Ti ) ≤ 0.15 (1)
However, G _Co is the weight of Co contained in the positive electrode active material-containing layer (mg), S _Co is the area of the positive electrode active material-containing layer (cm ² ), and G _Ti is the weight of Ti contained in the negative electrode active material-containing layer. (Mg) and _STi ^{are the areas (cm 2} ) of the negative electrode active material-containing layer.

According to another embodiment, a battery pack including the non-aqueous electrolyte battery according to the above embodiment is provided.

A partially cutaway perspective view showing an example of the battery according to the embodiment. FIG. 1 is an enlarged cross-sectional view of part A of the battery shown in FIG. A partially cutaway perspective view showing another example of the battery according to the embodiment. A partially cutaway perspective view showing still another example of the battery according to the embodiment. FIG. 4 is an enlarged cross-sectional view of a portion B of the battery shown in FIG. The exploded perspective view which shows an example of the battery pack which concerns on embodiment. The block diagram which shows an example of the electric circuit of the battery pack shown in FIG. The graph which shows the discharge potential curve of the positive electrode A which uses only the 1st positive electrode active material as an active material. The graph which shows the discharge potential curve of the positive electrode B which uses only the 2nd positive electrode active material as an active material. The graph which shows the discharge potential curve of the positive electrode C which uses the 1st positive electrode active material and the 2nd positive electrode active material as an active material. The graph which shows the charge / discharge potential curves of the positive electrode and the negative electrode of the non-aqueous electrolyte battery of embodiment which provided with a positive electrode C. The graph which shows the charge / discharge potential curves of the positive electrode and the negative electrode of the non-aqueous electrolyte battery of embodiment which provided with a positive electrode C.

A lithium ion secondary battery using lithium-containing manganese oxide for the positive electrode and lithium titanate for the negative electrode has excellent low-temperature output and longevity performance. On the other hand, such a battery has a problem that gas is generated. Further, there is a problem that the battery performance is deteriorated due to the elution of Mn from the positive electrode.

As a countermeasure against gas generation, an active material having a layered structure can be added. Among such active materials, lithium-containing cobalt oxide acts as a gas adsorbent, and therefore, gas generation is reduced by using both lithium-containing manganese oxide and lithium-containing cobalt oxide as the positive electrode active material.

However, the lithium-containing cobalt oxide has a problem that it is greatly deteriorated at a high potential. Therefore, the use of lithium-containing nickel-cobalt-manganese oxide as an alternative to lithium-containing cobalt oxide has been studied. Lithium-containing nickel-cobalt-manganese oxide has a large expansion and contraction when occluding and releasing lithium ions, and has a problem in cycle life performance.

Hereinafter, embodiments will be described with reference to the drawings. In addition, the same reference numerals are given to common configurations throughout the embodiment, and duplicate description will be omitted. In addition, each figure is a schematic view for facilitating the explanation of the embodiment and its understanding, and the shape, dimensions, ratio, etc. of the figure may differ from those of the actual device. The design can be changed as appropriate by taking into consideration.

(First Embodiment)
According to the first embodiment, a non-aqueous electrolyte battery including a positive electrode including a positive electrode active material-containing layer, a negative electrode including a negative electrode active material-containing layer, and a non-aqueous electrolyte is provided. The positive electrode active material-containing layer contains a positive electrode active material containing a lithium-containing manganese oxide as a first positive electrode active material and a lithium-containing nickel cobalt manganese oxide as a second positive electrode active material. The content of the second positive electrode active material in the positive electrode active material is 3 wt% or more and 20 wt% or less. The negative electrode active material-containing layer contains a lithium titanium-containing oxide. The non-aqueous electrolyte battery satisfies the following equation (1).

0.005 ≤ (G _Co / S _Co ) / (G _Ti / S _Ti ) ≤ 0.15 (1)
However, G _Co is the weight of Co contained in the positive electrode active material-containing layer (mg), S _Co is the area of the positive electrode active material-containing layer (cm ² ), and G _Ti is the weight of Ti contained in the negative electrode active material-containing layer. (Mg) and _STi ^{are the areas (cm 2} ) of the negative electrode active material-containing layer.

The reason for setting the content of the second positive electrode active material in the positive electrode active material within the above range and the reason _{for specifying the ratio of (G Co} / S _Co ) / (G _Ti / S _Ti ) within the range of Eq. (1). And explain.
If the content is less than 3 wt% or the _{ratio value represented by (G Co} / S _Co ) / (G _Ti / S _Ti ) is less than 0.005, the reduction decomposition of the non-aqueous electrolyte at the negative electrode Since the generated gas cannot be absorbed by the positive electrode, the cycle performance is inferior. Further, if the content exceeds 20 wt%, the cycle performance is inferior. On the other hand, when the _{ratio value represented by (G Co} / S _Co ) / (G _Ti / S _Ti ) exceeds 0.15, regardless of the magnitude of the deviation between the initial charge potential curve and the discharge potential curve of the positive electrode. However, the cycle performance will be inferior.

For the reasons described above, the content of the second positive electrode active material in the positive electrode active material is set within the above range, and _{the ratio of (G Co} / S _Co ) / (G _Ti / S _Ti ) is set to the formula (1). By specifying the range, it is possible to improve the cycle performance.

A more preferable range of the content of the second positive electrode active material in the positive electrode active material is 4 wt% or more and 10 wt% or less. Further, a more preferable range of the ratio value represented by _{(G Co} / S _Co ) / (G _Ti / S _{Ti) is 0.01 or more and 0.08 or less.} By specifying the value of the content or ratio of the second positive electrode active material in this range, or by specifying the values of both, the cycle performance can be further improved.

The (G _Co / S _Co ) / (G _Ti / S _Ti ) values are the composition of each of the first positive electrode active material and the second positive electrode active material, the weight ratio of the second positive electrode active material in the positive electrode active material, and the negative electrode active material. The desired value can be set by adjusting the composition of the above, the composition of the negative electrode active material-containing layer, or the amount (g / m ^{2) of each of the positive electrode and the negative electrode.}

The open circuit voltage of the positive electrode when the non-aqueous electrolyte battery is discharged to 1.8V at 0.2C should be 3.6V (vs.Li ^/ Li +) or more and 3.9V (vs.Li ^/ Li +) or less. Is desirable. By setting the open circuit voltage to 3.6 V (vs. Li ^/ Li +) or more, deterioration of the positive electrode due to over-discharging can be suppressed. In addition, by setting the open circuit voltage to 3.9 V (vs.Li ^/ Li +) or less, the range where the open circuit voltage of the positive electrode ^{is higher than 3.9 V (vs.Li /} Li +) is used as the charge / discharge region. Therefore, a high capacity can be obtained. The more preferable range of the open circuit voltage of the positive electrode when the non-aqueous electrolyte battery is discharged to 1.8 V at 0.2 C is 3.65 V (vs.Li ^/ Li +) or more and 3.80 V (vs.Li ^{/ Li +).} ) It is as follows.

8 to 12 show a discharge potential curve or a charge / discharge potential curve of the electrode. The positive electrode potential is the one when a constant current constant voltage (CCCV) is charged to 4.25 V at 0.2 C and then discharged to 3.1 V at 0.2 C. The negative electrode potential is the one when CCCV is charged to 1.4 V at 0.2 C and then discharged to 2 V at 0.2 C. The discharge potential curve of the positive electrode (hereinafter, positive electrode A) containing only the first positive electrode active material is shown in FIG. 8, and the positive electrode containing only the second positive electrode active material (hereinafter, positive electrode B) is shown in FIG. ) Is shown in FIG. 9, a positive electrode composed of a first positive electrode active material and a second positive electrode active material, and containing a positive electrode active material having a content of the second positive electrode active material of 10 wt% (hereinafter, positive electrode C). ) Is shown in FIG. In the graphs of FIGS. 8 to 10, the horizontal axis represents DOD (degree of discharge), and the vertical axis represents the positive electrode potential V (vs. Li ^/ Li +). As shown in FIG. 8, the potential of the positive electrode A is 4.0 V (vs.Li ^/ Li +) or more up to about 90% DOD, and steeply 3.0 V (vs.Li / Li +) when the DOD is around 100%. ^It descends to about +). As shown in FIG. 9, as for the potential of the positive electrode B, the positive electrode potential drops substantially continuously as the DOD progresses. Further, as shown in FIG. 10, the potential of the positive electrode C is 3.8 V or more until the DOD is about 90%, and drops sharply at around 100%. For a positive electrode having such a potential potential, for example, a first positive electrode active material and a second positive electrode active material are mixed, and the content of the second positive electrode active material in the positive electrode active material is 3 wt% or more and 20 wt%. It can be obtained by doing the following. When the non-aqueous electrolyte battery is discharged to 1.8 V at 0.2 C by adjusting the production conditions such as the composition of the non-aqueous electrolyte and the aging conditions using this positive electrode and the negative electrode containing lithium titanium-containing oxide. the open circuit voltage of the positive electrode can be less than or equal to 3.6V (vs.Li/Li ⁺⁾ or 3.9V (vs.Li/Li ^+).

Of the non-aqueous electrolyte batteries according to the embodiment having the positive electrode C and the negative electrode containing the lithium titanium-containing oxide, the charge / discharge potential curve of the non-aqueous electrolyte battery satisfying the open circuit voltage is shown in FIG. The charge / discharge potential curve of the non-aqueous electrolyte battery that does not satisfy the voltage is shown in FIG. The horizontal axis of FIGS. 11 and 12 is the capacity (Ah) of the battery, and the vertical axis is the potential V (vs. Li ^/ Li +).
In FIG. 11, the charge / discharge potential curve of the positive electrode C is shown by P ₁ , and the charge / discharge potential curve of the negative electrode is shown _{by N 1.} When _{the potential difference between P 1} and N ₁ is 1.8 V, the open circuit voltage of the positive electrode is, for example, 3.64 V (vs. Li / Li ⁺ ). As the over-discharge progresses, the positive electrode potential P ₁ decreases while the negative electrode potential N ₁ also increases, so that the over-discharge can be stopped in a state where the positive electrode potential P _{1 does not decrease extremely.}

On the other hand, in FIG. 12, a charge-discharge potential curve of the positive electrode A at P _2, shows a charge-discharge potential curve of the negative electrode with N _2. When _{the potential difference between P 2} and N ₂ is 1.8 V, the open circuit voltage of the positive electrode ^{is smaller than 3.6 V (vs. Li /} Li +) (for example, 3.55 ^{V (vs. Li / Li +} )). In this case, when the over-discharge proceeds, there is proceeded tendency decrease in positive electrode potential P _2.
Further, the charge-discharge range of the positive electrode 3.0V (vs.Li/Li ⁺⁾ or 4.25V charging capacity per unit area when (vs.Li/Li ⁺⁾ or less A (mAh ^{/ m} 2) When the charge / discharge range of the negative electrode is 1.4 ^{V (vs.Li / Li +} ) or more and 2.0 V (vs.Li / Li +) or less, the charge capacity per unit area is B (mAh / m ² ). At that time, it is desirable that the non-aqueous electrolyte battery satisfies 0.9 ≦ A / B ≦ 1.1 (2). Increasing the charge capacity ratio (A / B) has a small effect on the over-discharging of the positive electrode, but it is difficult for the positive electrode potential to rise, so that it is difficult to over-charge and the cycle characteristics can be improved. Therefore, the cycle performance of the battery can be improved by satisfying the equation (2): 0.9 ≦ A / B ≦ 1.1.

Hereinafter, the battery according to the embodiment will be described in detail.
(1) Positive electrode The positive electrode includes a positive electrode current collector and a positive electrode active material-containing layer supported on one or both surfaces of the positive electrode current collector.

The positive electrode active material-containing layer contains a lithium-containing manganese oxide as a first positive electrode active material and a lithium-containing nickel cobalt manganese oxide as a second positive electrode active material. The content of lithium-containing nickel-cobalt-manganese oxide in the positive electrode active material-containing layer is adjusted to 3 wt% or more and 20 wt% or less.

The lithium-containing manganese oxide includes, for example, spinel-type lithium manganate, which is a compound represented by _{the chemical formula LiMn 2-x} M _x O _4. Here, M is at least one selected from the group consisting of Mg, Ti, Cr, Fe, Co, Zn, Al, and Ga. The subscript x is 0.22 or more and 0.7 or less. Hereinafter, the lithium-containing manganese oxide may be referred to as “LMO”.

Lithium-containing nickel cobalt manganese oxide, for _{example, LiNi 1-yz Co y Mn} z O 2 ( where, 0 <y <1,0 <z <1 and 0 <y + z <1) including.

The positive electrode active material may contain other positive electrode active materials other than the first and second positive electrode active materials. The other positive electrode active material can include, for example, one or more compounds selected from the group consisting of lithium-containing cobalt oxide, lithium-containing nickel-cobalt composite oxide, and lithium-containing manganese-cobalt oxide. Examples of lithium-containing cobalt oxides include Li _w CoO ₂ . The range of the subscript w in the chemical formula Li _w CoO _{2 is 0 <w ≦ 1.} Examples of the lithium-nickel-cobalt composite _{oxide, LiNi 1-y Co y O} 2 ( where, 0 <y <1) including. Examples of lithium manganese cobalt oxide include LiMn _y Co _1-y O ₂ (where 0 <y <1).

The positive electrode active material is, for example, in the form of particles. When it is in the form of particles, the positive electrode active material may be primary particles or may be secondary particles in which primary particles are aggregated.

The average particle size of the particles of the first positive electrode active material is preferably 0.01 μm or more and 10 μm or less. Further, the average particle size of the particles of the second positive electrode active material is preferably 0.05 μm or more and 30 μm or less.

The positive electrode active material-containing layer may contain a binder and a conductive agent, if necessary.

The binder can bind the active material and the conductive agent. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorinated rubber. The type of binder used may be one or more.

The conductive agent can increase the electron conductivity and suppress the contact resistance with the current collector. The conductive agent includes, for example, a carbon material such as acetylene black, carbon black, graphite, carbon nanofibers or carbon nanotubes. The type of the conductive agent used may be one type or two or more types.

The blending ratio of the positive electrode active material, the conductive agent and the binder is preferably in the range of 80 to 95% by weight of the positive electrode active material, 3 to 18% by weight of the conductive agent and 2 to 7% by weight of the binder.

As the current collector, for example, a sheet containing a material having high electrical conductivity can be used. For example, an aluminum foil or an aluminum alloy foil can be used as the current collector. When an aluminum foil or an aluminum alloy foil is used, the thickness thereof is preferably 20 μm or less. The aluminum alloy foil may contain magnesium (Mg), titanium (Ti), zinc (Zn), manganese (Mn), silicon (Si) and the like. Further, the aluminum alloy foil may contain other transition metals. The content of the transition metal in the aluminum alloy foil is preferably 1% by mass or less. Examples of the transition metal include iron (Fe), copper (Cu), nickel (Ni), and chromium (Cr). The current collector is preferably an aluminum foil or an aluminum alloy foil containing aluminum and one or more elements selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si.

The current collector may include a portion that does not support an active material-containing layer on its surface. This portion can serve, for example, as an electrode current collecting tab. Alternatively, the electrode may further include an electrode current collector tab that is separate from the electrode current collector. A separate electrode current collecting tab can be electrically connected to the electrodes.

The thickness of the positive electrode is preferably 100 μm or less. Here, the thickness of the positive electrode is the total thickness of the positive electrode active material-containing layer and the positive electrode current collector. When the positive electrode active material-containing layer is supported on both sides of the positive electrode current collector, the total thickness of the two positive electrode active material-containing layers and the positive electrode current collector is the positive electrode thickness. By making the thickness of the positive electrode 100 μm or less, the resistance of the positive electrode can be lowered, so that the overvoltage applied to the positive electrode can be reduced. As a result, it is possible to suppress a decrease in the positive electrode potential at the end of discharge, so that deterioration due to over-discharge of the positive electrode can be suppressed. In order to secure a practical battery capacity, it is desirable that the thickness of the positive electrode is 30 μm or more.

The density of the positive electrode active material-containing layer is preferably 2.5 g / cc or more and 3.1 g / cc or less. As a result, even if the thickness of the positive electrode is as thin as 100 μm or less, it is possible to secure a positive electrode capacity that can withstand practical use.

The basis weight of the positive electrode active material-containing layer, that is, the weight per unit area (g / m ² ) can be 30 g / m ² or more and 130 g / m ² or less.

In the production of a positive electrode, for example, a positive electrode active material, a positive electrode conductive agent, and a binder are suspended in an appropriate solvent, and the obtained slurry is applied to a positive electrode current collector and dried to obtain a positive electrode active material-containing layer. After making, press. In addition, the positive electrode active material, the positive electrode conductive agent, and the binder may be formed in pellet form and used as the positive electrode active material-containing layer.
(2) Negative electrode The negative electrode includes a negative electrode current collector and a negative electrode active material-containing layer supported on one or both surfaces of the negative electrode current collector. The negative electrode active material-containing layer contains a lithium titanium-containing oxide.

The negative electrode current collector can include a portion that does not support a negative electrode active material-containing layer on the surface. This portion can serve as a negative electrode tab. Alternatively, the negative electrode may include a negative electrode tab that is separate from the negative electrode current collector.

Lithium titanium-containing oxides include, for example, lithium titanium oxide, lithium titanium composite oxide in which some of the constituent elements of lithium titanium oxide are replaced with different elements, orthocrystalline lithium titanium-containing oxide, and monoclinic type. Contains lithium niobium titanium-containing oxides. Lithium titanium oxide includes, for example, lithium titanate having a spinel type structure (for example, Li _{4 + x} Ti ₅ O ₁₂ (x is a value that changes with charge and discharge, 0 ≦ x ≦ 3)), and rams delite type titanium acid. Lithium (for example, Li _{2 + y} Ti ₃ O ₇ (y is a value that changes with charge and discharge, 0 ≦ y ≦ 3)) and the like can be mentioned. On the other hand, the molar ratio of oxygen _{is formally shown as 12 for spinel type Li 4 + x} Ti ₅ O 12 and 7 for rams delite type Li _{2 + y} Ti ₃ O ₇ , but these are due to the influence of oxygen non-stoikiometry and the like. The value of can change. The type of the negative electrode active material can be one type or two or more types.

The orbital lithium-titanium-containing oxide is represented by the general formula Li _{2 + w} Na _2-x M1 _y Ti _6-z M2 _z O _{14 + δ} , M1 is Cs and / or K, and M2 is Zr, Sn, Compounds containing at least one of V, Nb, Ta, Mo, W, Fe, Co, Mn, and Al can be mentioned, and 0 ≦ w ≦ 4, 0 ≦ x ≦ 2, 0 ≦ y ≦ 2, 0 ≦ z <6, −0.5 ≦ δ ≦ 0.5.

The monoclinic lithium niobium titanium-containing oxide is represented by the general formula Li _x Ti _1-y M3 _y Nb _2-z M4 _z O _{7 + δ} , where M3 is Zr, Si, Sn, Fe, Co, Mn and Ni. Examples include at least one compound selected from the group consisting of, and M4 being at least one compound selected from the group consisting of V, Nb, Ta, Mo, W and Bi, 0≤x≤5,0. ≦ y <1, 0 ≦ z <2, −0.3 ≦ δ ≦ 0.3.

The lithium-titanium-containing oxide is, for example, in the form of particles. When it is in the form of particles, the lithium-titanium-containing oxide may be primary particles or may be secondary particles in which primary particles are aggregated.

The average particle size of the lithium titanium-containing oxide particles is preferably 0.01 μm or more and 10 μm or less.

The negative electrode active material-containing layer may contain a conductive agent and a binder, if necessary.

Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyimide, polyamide and the like. The type of binder can be one or more.

Examples of the negative electrode conductive agent include carbon black such as acetylene black and Ketjen black, graphite, carbon fiber, carbon nanotube, and fullerene. The type of the conductive agent can be one type or two or more types.

The blending ratio of the negative electrode active material, the conductive agent and the binder in the negative electrode active material-containing layer is 70% by weight or more and 96% by weight or less of the negative electrode active material, 2% by weight or more and 28% by weight or less of the conductive agent, and 2% by weight of the binder. It is preferably 28% by weight or more.

The density of the negative electrode active material-containing layer ^{is preferably 2.0 g / cm 3} or more.

The current collector is preferably an aluminum foil or an aluminum alloy foil. When an aluminum foil or an aluminum alloy foil is used, the thickness thereof is preferably 20 μm or less. The aluminum alloy foil may contain magnesium (Mg), titanium (Ti), zinc (Zn), manganese (Mn), silicon (Si) and the like. Further, the aluminum alloy foil may contain other transition metals. The content of the transition metal in the aluminum alloy foil is preferably 1% by mass or less. Examples of the transition metal include iron (Fe), copper (Cu), nickel (Ni), and chromium (Cr). The current collector is preferably an aluminum foil or an aluminum alloy foil containing aluminum and one or more elements selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si.

For the negative electrode, for example, a negative electrode active material, a negative electrode conductive agent, and a binder are suspended in an appropriate solvent, and the obtained slurry is applied to a negative electrode current collector and dried to prepare a negative electrode active material-containing layer. It is produced by pressing. In addition, the negative electrode active material, the negative electrode conductive agent, and the binder may be formed in pellet form and used as the negative electrode active material-containing layer.

The thickness of the negative electrode can be in the range of 20 μm or more and 80 μm or less. Here, the thickness of the negative electrode is the total thickness of the negative electrode active material-containing layer and the negative electrode current collector. When the negative electrode active material-containing layers are supported on both sides of the negative electrode current collector, the total thickness of the two negative electrode active material-containing layers and the negative electrode current collector is the negative electrode thickness.

The basis weight of the negative electrode active material-containing layer, that is, the weight per unit area (g / m ² ) can be 10 g / m ² or more and 80 g / m ² or less.
(3) Non-aqueous electrolyte Non-aqueous electrolyte includes a liquid non-aqueous electrolyte prepared by dissolving an electrolyte in a non-aqueous solvent, a gel-like non-aqueous electrolyte obtained by combining a liquid non-aqueous electrolyte and a polymer material, and the like.

The electrolytes are, for example, lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium arsenic hexafluoride (LiAsF ₆ ), lithium difluorophosphate. (LiPO ₂ F ₂ ), Lithium Trifluorometasulfonate (LiCF ₃ SO ₃ ), Lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO ₂ ) ₂ ], Lithium tetrafluorofluorofluoride (LiAlF ₄ ), The following 1 Examples of lithium salts such as lithium difluorobisoxalate phosphate (LiDFBOP) shown in the above can be mentioned. These electrolytes may be used alone or in admixture of two or more. The electrolyte preferably contains lithium hexafluorophosphate. More preferred electrolytes include lithium hexafluorophosphate as the first electrolyte and at least one of lithium tetrafluoroboate and lithium difluorobisoxalate phosphate as the second electrolyte. A non-aqueous electrolyte containing an electrolyte having this composition can form a lithium ion conductive protective film on the surface of the negative electrode. By forming the protective film, the charge / discharge potential of the negative electrode at the end of discharge can be shifted to your side.

The electrolyte is preferably dissolved in a non-aqueous solvent in the range of 0.5 mol / L or more and 2.5 mol / L or less.

When the non-aqueous electrolyte contains the second electrolyte, the second electrolyte is preferably dissolved in a non-aqueous solvent in the range of 0.01 mol / L or more and 0.5 mol / L or less. By setting the concentration of the second electrolyte to 0.01 mol / L or more, a protective film having lithium ion conductivity can be uniformly formed on the surface of the negative electrode. By setting the concentration of the second electrolyte to 0.5 mol / L or less, it is possible to suppress an increase in the negative electrode resistance due to the formation of the protective film.

The non-aqueous solvent is, for example, a cyclic carbonate such as ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC); a chain such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC). Hydrocarbons; cyclic ethers such as tetrahydrofuran (THF), dimethyltetrahydrofuran (2MeTHF); chain ethers such as dimethoxyethane (DME); cyclic esters such as γ-butyrolactone (BL); methyl acetate, ethyl acetate, methyl propionate , Chain esters such as ethyl propionate; organic solvents such as acetonitrile (AN); sulfolane (SL). These organic solvents can be used alone or in the form of a mixture of two or more.

Examples of the polymer material used for the gel-like non-aqueous electrolyte include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO) and the like.

The positive electrode and the negative electrode can form an electrode group. In the electrode group, the positive electrode active material-containing layer and the negative electrode active material-containing layer can face each other via, for example, a separator.

The electrode group can have various structures. For example, the electrode group can have a stack type structure. The electrode group having a stack type structure can be obtained, for example, by alternately stacking a plurality of positive electrodes and a plurality of negative electrodes with a separator sandwiched between the positive electrode active material-containing layer and the negative electrode active material-containing layer. Alternatively, the electrode group can have a wound structure. In the winding type electrode group, for example, one separator, one negative electrode, another separator, and one positive electrode are laminated in this order to form a laminated body, and this laminated body is formed. It can be obtained by turning.

The material of the separator is not particularly limited. The separator is preferably electrically insulating. As the separator, for example, a porous film, a microporous film, a woven fabric, or a non-woven fabric, or a laminate of the same material or a different material among them can be used. Examples of the material for forming the separator include polymers such as polyethylene, polypropylene, ethylene-propylene copolymer polymer, ethylene-butene copolymer polymer, polyolefin, cellulose, polyethylene terephthalate, and vinylon. The material of the separator may be one kind, or two or more kinds may be used in combination.

The thickness of the separator is preferably 2 μm or more and 30 μm or less.

The non-aqueous electrolyte battery according to the embodiment may further include a positive electrode terminal and a negative electrode terminal. A part of the positive electrode terminal is electrically connected to a part of the positive electrode, so that the positive electrode terminal can function as a conductor for electrons to move between the positive electrode and the external terminal. The positive electrode terminal can be connected to, for example, a positive electrode current collector, particularly a positive electrode tab. Similarly, the negative electrode terminal can act as a conductor for electrons to move between the negative electrode and the external terminal by electrically connecting a part of the negative electrode terminal to a part of the negative electrode. The negative electrode terminal can be connected to, for example, a negative electrode current collector, particularly a negative electrode tab.

The exterior member houses the electrode group and the non-aqueous electrolyte. The non-aqueous electrolyte can be impregnated in the electrode group within the exterior member. A part of each of the positive electrode terminal and the negative electrode terminal can also be extended from the exterior member.

The exterior member may be formed of a laminated film or may be composed of a metal container. When using a metal container, the lid can be integral with or separate from the container. The wall thickness of the metal container is more preferably 0.5 mm or less and 0.2 mm or less. Examples of the shape of the exterior member include a flat type, a square type, a cylindrical type, a coin type, a button type, a sheet type, and a laminated type. In addition to a small battery loaded in a portable electronic device or the like, a large battery loaded in a two-wheeled or four-wheeled automobile may be used.

It is desirable that the wall thickness of the laminated film exterior member is 0.2 mm or less. An example of a laminated film is a multilayer film containing a resin film and a metal layer arranged between the resin films. The metal layer is preferably an aluminum foil or an aluminum alloy foil for weight reduction. As the resin film, for example, a polymer material such as polypropylene (PP), polyethylene (PE), nylon, or polyethylene terephthalate (PET) can be used. The laminated film can be sealed into the shape of an exterior member by heat fusion.

The metal container is made of aluminum or an aluminum alloy or the like. As the aluminum alloy, an alloy containing elements such as magnesium, zinc, and silicon is preferable. In aluminum or an aluminum alloy, it is preferable that the content of transition metals such as iron, copper, nickel and chromium is 100 ppm or less in order to dramatically improve long-term reliability and heat dissipation in a high temperature environment.

It is desirable that the metal container made of aluminum or an aluminum alloy has an average crystal grain size of 50 μm or less, more preferably 30 μm or less, still more preferably 5 μm or less. By setting the average crystal grain size to 50 μm or less, the strength of the metal container made of aluminum or an aluminum alloy can be dramatically increased, and the container can be further thinned. As a result, it is possible to realize a non-aqueous electrolyte battery suitable for in-vehicle use, which is lightweight, has high output, and has excellent long-term reliability.

Next, a specific example of the non-aqueous electrolyte battery according to the embodiment will be described with reference to the drawings.

First, the non-aqueous electrolyte battery of the first example according to the embodiment will be described with reference to FIGS. 1 and 2.

FIG. 1 is a partially cutaway perspective view of an example of a non-aqueous electrolyte battery according to the embodiment. FIG. 2 is an enlarged cross-sectional view of part A of the non-aqueous electrolyte battery shown in FIG.

The non-aqueous electrolyte battery 100 shown in FIGS. 1 and 2 includes a flat electrode group 1 and an exterior member 7 made of a laminated film. The flat electrode group 1 includes a negative electrode 2, a positive electrode 3, and a separator 4. In the flat electrode group 1, the negative electrode 2 and the positive electrode 3 are wound in a flat shape with a separator 4 interposed therebetween.

As shown in FIG. 2, the negative electrode 2 includes a negative electrode current collector 2a and a negative electrode active material-containing layer 2b supported on the negative electrode current collector 2a. As shown in FIG. 2, in the outermost portion of the negative electrode 2, the negative electrode active material-containing layer 2b is placed on the main surface of the two main surfaces of the negative electrode current collector 2a that does not face the positive electrode 3. Not supported. In the other portion of the negative electrode 2, the negative electrode active material-containing layer 2b is supported on both main surfaces of the negative electrode current collector. As shown in FIG. 2, the positive electrode 3 includes a positive electrode current collector 3a and a positive electrode active material-containing layer 3b supported on two main surfaces of the positive electrode current collector 3a.

A band-shaped negative electrode terminal 5 is electrically connected to the negative electrode 2. A band-shaped positive electrode terminal 6 is electrically connected to the positive electrode 3.

The electrode group 1 is housed in the exterior member 7 made of a laminated film in a state in which the ends of the negative electrode terminal 5 and the positive electrode terminal 6 extend from the exterior member 7. A non-aqueous electrolyte (not shown) is housed in the laminated film exterior member 7. The non-aqueous electrolyte is impregnated in the electrode group 1. The exterior member 7 made of a laminated film is sealed by heat-sealing each of the end portion and the two ends orthogonal to the end portion with the negative electrode terminal 5 and the positive electrode terminal 6 sandwiched at one end portion. ing.

Next, another example of the battery according to the embodiment will be described in detail with reference to FIG. FIG. 3 is a partially cutaway perspective view showing another example of the battery according to the embodiment.

The battery 100 shown in FIG. 3 is different from the battery 100 shown in FIGS. 1 and 2 in that the exterior member is composed of the metal container 17a and the sealing plate 17b.

The flat electrode group 1 includes a negative electrode, a positive electrode, and a separator, similarly to the electrode group 1 in the battery 100 shown in FIGS. 1 and 2. Further, the electrode group 1 has a similar structure between FIGS. 1 and 3. However, in FIG. 3, instead of the negative electrode terminal 5 and the positive electrode terminal 6, the negative electrode lead 15a and the positive electrode lead 16a are electrically connected to the negative electrode and the positive electrode, respectively, as will be described later.

In the battery 100 shown in FIG. 3, such an electrode group 1 is housed in a metal container 17a. The metal container 17a further contains an electrolyte (not shown). The metal container 17a is sealed by a metal sealing plate 17b. The metal container 17a and the sealing plate 17b form, for example, an outer can as an outer member.

One end of the negative electrode lead 15a is electrically connected to the negative electrode current collector, and the other end is electrically connected to the negative electrode terminal 15. One end of the positive electrode lead 16a is electrically connected to the positive electrode current collector, and the other end is electrically connected to the positive electrode terminal 16 fixed to the sealing plate 17b. The positive electrode terminal 16 is fixed to the sealing plate 17b via an insulating member 17c. The positive electrode terminal 16 and the sealing plate 17b are electrically insulated by an insulating member 17c.

4 and 5 show a battery including a stack-type electrode group as yet another example of the battery. FIG. 4 is a partially cutaway perspective view showing still another example of the battery according to the embodiment. FIG. 5 is an enlarged cross-sectional view of a portion B of the battery shown in FIG.

The battery 100 of the example shown in FIGS. 4 and 5 includes the electrode group 1 shown in FIGS. 4 and 5, the outer container 7 shown in FIGS. 4 and 5, and the positive electrode terminal 6 shown in FIGS. 4 and 5. It is provided with the negative electrode terminal 5 shown in 4.

The electrode group 1 shown in FIGS. 4 and 5 includes a plurality of positive electrodes 3, a plurality of negative electrodes 2, and a single separator 4.

As shown in FIG. 5, each positive electrode 3 includes a positive electrode current collector 3a and a positive electrode active material-containing layer 3b formed on both sides of the positive electrode current collector 3a. Further, as shown in FIG. 5, the positive electrode current collector 3a includes a portion where the positive electrode active material-containing layer 3b is not formed on the surface thereof. This portion acts as a positive electrode current collecting tab 3c.

Each negative electrode 2 includes a negative electrode current collector 2a and a negative electrode active material-containing layer 2b formed on both sides of the negative electrode current collector 2a. Further, the negative electrode current collector 2a includes a portion where the negative electrode active material-containing layer 2b is not formed on the surface (not shown). This part acts as a negative electrode current collector tab.

As shown in part in FIG. 5, the separator 4 is zigzag. A positive electrode 3 or a negative electrode 2 is arranged in a space defined by faces of the zigzag separators 4 facing each other. As a result, as shown in FIG. 5, the positive electrode 3 and the negative electrode 2 are laminated so that the positive electrode active material-containing layer 3b and the negative electrode active material-containing layer 2b face each other with the separator 4 interposed therebetween. Thus, the electrode group 1 is formed.

As shown in FIG. 5, the positive electrode current collecting tab 3c of the electrode group 1 extends beyond the respective ends of the positive electrode active material-containing layer 3b and the negative electrode active material-containing layer 2b. As shown in FIG. 5, these positive electrode current collecting tabs 3c are grouped together and connected to the positive electrode terminal 6. Although not shown, the negative electrode current collecting tab of the electrode group 1 also extends beyond the other end of each of the positive electrode active material-containing layer 3b and the negative electrode active material-containing layer 2b. Although these negative electrode current collecting tabs are not shown, they are grouped together and connected to the negative electrode terminal 5 shown in FIG.

As shown in FIGS. 4 and 5, such an electrode group 1 is housed in an exterior member made of a laminated film outer container 7.

The outer container 7 is formed of an aluminum-containing laminated film composed of an aluminum foil 71 and resin films 72 and 73 formed on both sides thereof. The aluminum-containing laminated film forming the outer container 7 is bent so that the resin film 72 faces inward with the bent portion 7d as a crease, and accommodates the electrode group 1. Further, as shown in FIGS. 4 and 5, in the peripheral edge portion 7b of the outer container 7, the portions of the resin film 72 facing each other sandwich the positive electrode terminal 6 between them. Similarly, in the peripheral edge portion 7c of the outer container 7, the portions of the resin film 72 facing each other sandwich the negative electrode terminal 5 between them. The positive electrode terminal 6 and the negative electrode terminal 5 extend from the outer container 7 in opposite directions.

In the peripheral portions 7a, 7b and 7c of the outer container 7 excluding the portions sandwiching the positive electrode terminal 6 and the negative electrode terminal 5, the portions of the resin film 72 facing each other are heat-sealed.

Further, in the battery 100, in order to improve the bonding strength between the positive electrode terminal 6 and the resin film 72, an insulating film 9 is provided between the positive electrode terminal 6 and the resin film 72 as shown in FIG. Further, at the peripheral edge portion 7b, the positive electrode terminal 6 and the insulating film 9 are heat-sealed, and the resin film 72 and the insulating film 9 are heat-sealed. Similarly, although not shown, an insulating film 9 is also provided between the negative electrode terminal 5 and the resin film 72. Further, in the peripheral edge portion 7c, the negative electrode terminal 5 and the insulating film 9 are heat-sealed, and the resin film 72 and the insulating film 9 are heat-sealed. That is, in the battery 100 shown in FIG. 5, all of the peripheral portions 7a, 7b, and 7c of the outer container 7 are heat-sealed.

The outer container 7 further contains an electrolyte (not shown). The electrolyte is impregnated in the electrode group 1.

In the battery 100 shown in FIGS. 4 and 5, as shown in FIG. 5, a plurality of positive electrode current collecting tabs 3c are grouped in the lowermost layer of the electrode group 1. Similarly, although not shown, a plurality of negative electrode current collecting tabs are grouped in the lowermost layer of the electrode group 1. However, for example, a plurality of positive electrode current collecting tabs 3c and a plurality of negative electrode current collecting tabs can be combined into one near the middle stage of the electrode group 1 and connected to each of the positive electrode terminal 6 and the negative electrode terminal 5.

According to the non-aqueous electrolyte battery of the first embodiment described above, a positive electrode active material-containing layer containing a positive electrode active material containing a lithium-containing manganese oxide and a lithium-containing nickel cobalt manganese oxide, and a lithium titanium-containing oxide. Includes a negative electrode active material-containing layer containing. The content of lithium-containing nickel-cobalt-manganese oxide in the positive electrode active material is 3 wt% or more and 20 wt% or less. The non-aqueous electrolyte battery satisfies the following equation (1).

0.005 ≤ (G _Co / S _Co ) / (G _Ti / S _Ti ) ≤ 0.15 (1)
According to the non-aqueous electrolyte battery, it is possible to suppress over-discharging of the positive electrode and improve the charge / discharge cycle life performance.

(Second Embodiment)
According to the second embodiment, a battery pack is provided. This battery pack includes the battery according to the first embodiment.

The battery pack according to the embodiment may also include a plurality of batteries. Multiple batteries can be electrically connected in series or electrically in parallel. Alternatively, a plurality of batteries can be electrically connected in series and in parallel. That is, the battery pack according to the embodiment may include an assembled battery. The number of assembled batteries can be multiple. Multiple battery packs can be electrically connected in series, in parallel, or in a combination of series and parallel.

An example of the battery pack according to the embodiment will be described below with reference to FIGS. 6 and 7. FIG. 6 is an exploded perspective view showing an example of the battery pack according to the embodiment. FIG. 7 is a block diagram showing an example of the electric circuit of the battery pack shown in FIG.

The battery pack 20 shown in FIGS. 6 and 7 includes a plurality of cell cells 21. The cell 21 may be, for example, an example flat battery 100 according to the embodiment described with reference to FIG.

The plurality of cell cells 21 are laminated so that the negative electrode terminals 5 and the positive electrode terminals 6 extending to the outside are aligned in the same direction, and are fastened with the adhesive tape 22 to form the assembled battery 23. These cell cells 21 are electrically connected in series with each other as shown in FIG.

The printed wiring board 24 is arranged so as to face the side surface on which the negative electrode terminal 5 and the positive electrode terminal 6 of the cell 21 extend. As shown in FIG. 7, the printed wiring board 24 is equipped with a thermistor 25, a protection circuit 26, and a terminal 27 for energizing an external device. An insulating plate (not shown) is attached to the printed wiring board 24 on the surface facing the assembled battery 23 in order to avoid unnecessary connection with the wiring of the assembled battery 23.

The positive electrode side lead 28 is connected to the positive electrode terminal 6 located at the bottom layer of the assembled battery 23, and the tip thereof is inserted into the positive electrode side connector 29 of the printed wiring board 24 and electrically connected. The negative electrode side lead 30 is connected to the negative electrode terminal 5 located on the uppermost layer of the assembled battery 23, and the tip thereof is inserted into the negative electrode side connector 31 of the printed wiring board 24 and electrically connected. These connectors 29 and 31 are connected to the protection circuit 26 through the wirings 32 and 33 formed on the printed wiring board 24.

The thermistor 25 detects the temperature of the cell 21 and the detection signal is transmitted to the protection circuit 26. The protection circuit 26 can cut off the positive side wiring 34a and the negative side wiring 34b between the protection circuit 26 and the energizing terminal 27 to the external device under predetermined conditions. An example of the predetermined condition is when the detection temperature of the thermistor 25 becomes equal to or higher than the predetermined temperature. Further, another example of the predetermined condition is when the overcharge, overdischarge, overcurrent, or the like of the cell 21 is detected. The detection of overcharging or the like is performed on the individual cell 21 or the entire assembled battery 23. When detecting the individual cell 21, the battery voltage may be detected, or the positive electrode potential or the negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each cell 21. In the battery pack 20 of FIGS. 6 and 7, a wiring 35 for voltage detection is connected to each of the cell 21. The detection signal is transmitted to the protection circuit 26 through these wires 35.

Protective sheets 36 made of rubber or resin are arranged on the three side surfaces of the assembled battery 23 except for the side surfaces on which the positive electrode terminals 6 and the negative electrode terminals 5 project.

The assembled battery 23 is housed in the storage container 37 together with the protective sheet 36 and the printed wiring board 24. That is, the protective sheet 36 is arranged on both inner side surfaces along the long side direction and the inner side surface along the short side direction of the storage container 37, and the inside along the other short side direction on the opposite side via the assembled battery 23. The printed wiring board 24 is arranged on the side surface. The assembled battery 23 is located in a space surrounded by the protective sheet 36 and the printed wiring board 24. The lid 38 is attached to the upper surface of the storage container 37.

A heat-shrinkable tape may be used instead of the adhesive tape 22 to fix the assembled battery 23. In this case, protective sheets are arranged on both side surfaces of the assembled battery, the heat-shrinkable tape is circulated, and then the heat-shrinkable tape is heat-shrinked to bind the assembled battery.

Although FIGS. 6 and 7 show a form in which the cells 21 are electrically connected in series, they may be electrically connected in parallel in order to increase the battery capacity. Further, the assembled battery packs can be electrically connected in series and / or in parallel.

In addition, the mode of the battery pack according to the embodiment is appropriately changed depending on the intended use. As the use of the battery pack according to the embodiment, those in which cycle performance in charging / discharging a large current is desired are preferable. Specific applications include power supplies for digital cameras, two-wheeled to four-wheeled hybrid electric vehicles, two-wheeled to four-wheeled electric vehicles, and in-vehicle use such as assisted bicycles. As the use of the battery pack according to the embodiment, it is particularly suitable for in-vehicle use.

The battery pack according to the second embodiment includes the battery according to the first embodiment. Therefore, the battery pack according to the embodiment has excellent life performance.

Hereinafter, the content of the second positive electrode active material in the positive electrode active material, the (G _Co / S _Co ) / (G _Ti / S _Ti ) value, the open circuit voltage of the positive electrode, the thickness and density of the positive electrode and the negative electrode are measured. The method will be described. First, a method of taking out the positive electrode will be described.

<How to take out the positive electrode>
The battery is completely discharged to set the charge state (State of charge (SOC)) to 0%. This battery is disassembled, and a positive electrode is cut out about 2 cm square. The cut positive electrode is ^{immersed in 50 cc (cm 3} ) of ethyl methyl carbonate and left for 1 hour. Then, in order to dry the positive electrode, it is vacuum dried for 1 hour to obtain a measurement sample. The operations up to this point are performed in a glove box with an argon atmosphere.

<Measurement of composition of active material>
The composition of the active material contained in the electrode can be measured as follows.

The active material-containing layer is peeled off from the electrode as the measurement sample using, for example, a spatula to obtain a powdery sample.

The crystal structure of the active material is identified by X-Ray Diffraction (XRD) measurements on the powdered sample. The measurement is performed using CuKα ray as a radiation source in a measurement range in which 2θ is 10 ° or more and 90 ° or less. By this measurement, the X-ray diffraction pattern of the compound contained in the selected particles can be obtained.

As a device for measuring powder X-ray diffraction, for example, SmartLab manufactured by Rigaku Co., Ltd. is used. The measurement conditions are as follows:
X-ray source: Cu target Output: 45kV, 200mA
Solar slit: 5 ° for both incident and light reception
Step width: 0.02 deg
Scan speed: 20 deg / min Semiconductor detector: D / teX Ultra 250
Sample plate holder: Flat glass sample plate holder (thickness 0.5 mm)
Measurement range: Range of 10 ° ≤ 2θ ≤ 90 °.

When using other equipment, measure using standard Si powder for powder X-ray diffraction so that the same measurement results as above can be obtained, and make sure that the peak intensity and peak top position match those of the above equipment. Adjust and measure.

Subsequently, the sample containing the active material is observed with a scanning electron microscope (SEM). Even in SEM observation, it is desirable to prevent the sample from coming into contact with the atmosphere and to perform it in an inert atmosphere such as argon or nitrogen.

For example, in a 3000 times SEM observation image, some particles having the form of primary particles or secondary particles confirmed in the field of view are selected. At this time, the selected particles are selected so that the particle size distribution is as wide as possible. The types and compositions of the constituent elements of the active material are identified by EDX analysis of the observed active material particles. This makes it possible to specify the type and amount of elements other than Li among the elements contained in each of the selected particles. Perform the same operation for each of the plurality of active material particles to determine the mixed state of the active material particles.

Subsequently, as described above, the powdered sample collected from the active material-containing layer is washed with acetone and dried. The obtained powder is dissolved in hydrochloric acid, the conductive agent is filtered off, and then diluted with ion-exchanged water to prepare a measurement sample. The metal content ratio in the measurement sample is calculated by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) analysis method.

When there are multiple types of active materials, the mass ratio is estimated from the content ratio of the elements unique to each active material. The ratio of the unique element to the mass of the active material is judged from the composition of the constituent elements obtained by EDX analysis. For example, the measurement sample obtained from the active material-containing layer may contain lithium-containing manganese oxide as the first active material and lithium-containing nickel cobalt manganese oxide as the second active material. In this case, the chemical formulas and formula amounts of the first and second active materials are calculated from the obtained metal ratios, and the weight ratios of the first and second active materials contained in the collected active material-containing layer of a predetermined weight are obtained. From the weight ratio of the first and second active materials, the content of the second active material in the positive electrode active material is obtained.
<Measurement method of (G _Co / S _Co ) / (G _Ti / S _{Ti) value>}
Analysis method of Co in the positive electrode 1) S _Co (cm ² ) is cut out from the positive electrode and sampled in a beaker.
2) Dissolve the active material using hydrochloric acid and hydrogen peroxide solution.
3) Filter, receive the filtrate and wash in a volumetric flask, and add water up to the marked line. This is used as a sample solution.
4) Preliminary determination of Co is performed by ICP emission spectrometry, and from the result, the sample solution is diluted so that the Co concentration becomes 5 to 10 μg / ml (D).
5) Co is quantified by ICP emission spectrometry. At this time, standard solutions having a Co concentration of 0 μg / ml, 5 μg / ml, and 10 μg / ml are used, and quantification is performed by a calibration curve method (C).
6) Calculate the amount of Co by the following formula (2).

G _Co (mg) = C × D × V × 10 ^-3 (2)
However, C is the Co concentration in the diluted solution (μg / ml), D is the dilution ratio, V is the volume of the volumetric flask (ml), and ^10-3 is the coefficient for converting μg to mg.

Analysis method of Ti in the negative electrode (1) S _Ti (cm ² ) is cut out from the negative electrode and sampled in a beaker.
(2) Dissolve the Al foil with hydrochloric acid.
(3) Sulfuric acid is added and heated to dissolve most of the active material.
(4) Add water to dilute, filter, receive the filtrate and wash in a volumetric flask A, and add water up to the marked line. This is referred to as sample solution A. The insoluble matter is used in the subsequent steps shown in (5).
(5) Transfer the insoluble matter together with the filter paper to a platinum crucible, and heat it with a gas burner or an electric furnace to incinerate it.
(6) Potassium divalent acid is added, and the mixture is heated and melted using an electric furnace.
(7) Dissolve in 10 ml of a diluted solution by adding 20 volumes of water per volume of sulfuric acid.
(8) Filter with filter paper type 5 C, receive the filtrate and washing liquid in a volumetric flask B, and add water up to the marked line. This is referred to as sample solution B.
(9) Preliminary determination of sample solution A is performed by ICP emission spectrometry, and the sample solution is diluted from the result so that the Ti concentration becomes 5 to 10 μg / ml (DA).
(10) Ti is quantified by ICP emission spectrometry. At this time, standard solutions having Ti concentrations of 0 μg / ml, 5 μg / ml, and 10 μg / ml are used, and quantification is performed by the calibration curve method (CA).
(11) Preliminary determination of sample solution B is performed by ICP emission spectrometry, and based on the results, the sample solution is diluted so that the Ti concentration is 10 μg / ml or less (DB).
(12) Ti is quantified by ICP emission spectrometry. At this time, a standard solution in which potassium divalent acid is added at a Ti concentration of 0 μg / ml, 5 μg / ml, and 10 μg / ml is used, and quantification is performed by a calibration curve method (CB).
(13) The Ti amount is calculated by the following equation (3).

G _Ti (mg) = CA x DA x VA x 10 ^-3 + CB x DB x VB x 10 ^-3 (3)
However, CA is the Ti concentration (μg / ml) in the diluted solution of sample solution A, DA is the dilution ratio of sample solution A, VA is the volume of female flask A (ml), and ^10-3 is μg converted to mg. CB is the Ti concentration (μg / ml) in the diluted solution of the sample solution B, DB is the dilution ratio of the sample solution B, and VB is the volume (ml) of the measuring flask B.

Method of calculating the value of (G _Co / S _Co ) / (G _Ti / S _{Ti ) As S Co} (cm ² ) of the positive electrode, the total area of the positive electrode active material-containing layers formed on each surface of the positive electrode current collector is totaled. Find the value. Further, as the S _Ti (cm ² ) of the negative electrode, the total area of the negative electrode active material-containing layers formed on each surface of the negative electrode current collector is obtained.

From the values of _{G Co} , S _Co , G _Ti , and S _Ti obtained above _{, (G Co} / S _Co ) / (G _Ti / S _Ti ) is calculated.
<Measurement of positive electrode open circuit voltage>
The non-aqueous electrolyte battery is charged at 0.2 C to 4.25 V with a constant current and constant voltage (CCCV), and then discharged at 0.2 C to 1.8 V. Next, the non-aqueous electrolyte battery is disassembled in an Ar atmosphere, and the electrode group is taken out. A positive electrode is cut out from the taken-out electrode group. _{The positive electrode and the counter electrode metal Li are immersed in an electrolytic solution in which 1 mol / L LiPF 6} is dissolved in a mixed solvent of ethyl methyl carbonate (EMC) and ethylene carbonate (EC), and the metal is subjected to a tester. The positive electrode potential with respect to Li is measured, and the opening circuit voltage V (vs. Li / Li ⁺ ) of the positive electrode at the time of discharging to 1.8 V at 0.2 C is used. Note that 1C is a current value capable of charging and discharging the nominal capacity of the non-aqueous electrolyte battery in 1 hour.
<Measurement method of the thickness of each of the positive electrode and the negative electrode and the density of the active material-containing layer>
First, the thickness of the electrode is measured using a thickness measuring machine. The obtained value is taken as the thickness of the positive electrode or the negative electrode.
Next, the electrode is punched to a size of 1 cm × 1 cm using a cutting machine to obtain an electrode sample. Next, the mass of this electrode sample is measured. Next, the active material-containing layer is removed from the electrode sample by immersing the electrode sample in a solvent such as N-methylpyrrolidone. The solvent used for peeling off the active material-containing layer is not particularly limited as long as it does not erode the current collector and can peel off the active material-containing layer. Next, the thickness and mass of the current collector sample are measured.

Next, the thickness of the active material-containing layer is calculated by subtracting the thickness of the current collector sample from the thickness of the electrode sample. From this thickness, the volume of the active material-containing layer is calculated. Further, the mass of the active material-containing layer is calculated by subtracting the mass of the current collector sample from the mass of the electrode sample. ^{Next, the density (g / cm 3} ) of the active material-containing layer is calculated by dividing the mass of the active material-containing layer by the volume of the active material-containing layer.

Hereinafter, examples will be described in detail.
(Example 1)
Preparation of positive electrode As the positive electrode active material, 90% by weight of the first positive electrode active material composed of lithium-containing manganese oxide particles having an average particle size of 5 μm represented by _{LiMn 1.7} Al _0.3 O _{4 and LiNi 0.5} Co _0.2 Mn _0.3 O _{A second} positive electrode active material composed of lithium-containing nickel-cobalt-manganese oxide particles having an average particle size of 5 μm represented by 2 was prepared in an amount of 10% by weight. In the positive electrode active material, acetylene black as a conductive agent and polyvinylidene fluoride (PVdF) as a binder were dispersed in N-methylpyrrolidone (NMP) at a weight ratio of 90: 5: 5. The obtained dispersion liquid was applied onto a current collector made of an aluminum foil having a thickness of 15 μm, dried, and pressed to provide a positive electrode active material-containing layer. Table 1 below shows the basis weight of one side of the positive electrode, the density of the positive electrode, and the thickness of the positive electrode.

Preparation of Negative Electrode As the negative electrode active material, lithium titanate particles having an average particle size of 3 μm represented by _{Li 4} Ti ₅ O _{12 were prepared.} Graphite as a conductive agent and polyvinylidene fluoride as a binder were dispersed in N-methylpyrrolidone (NMP) as a negative electrode active material at a weight ratio of 95: 3: 2. The obtained dispersion liquid was applied onto a current collector made of an aluminum foil having a thickness of 15 μm, dried, and pressed to provide a negative electrode active material-containing layer. Table 2 below shows the basis weight of one side of the negative electrode, the density of the negative electrode, and the thickness of the negative electrode.
As a separator, a cellulose non-woven fabric separator having a thickness of 15 μm was prepared. A group of spiral electrodes was prepared by winding so that a separator was arranged between the positive electrode and the negative electrode. The electrode group was housed in an aluminum container. This was put into a dryer and vacuum dried at 95 ° C. for 6 hours. After drying, it was carried to a glove box controlled to have a dew point of -50 ° C or lower. Into the container, 70 cc of an electrolytic solution prepared by dissolving _{1 mol / L of LiPF 6} in a mixed solvent of ethyl methyl carbonate (MEC) and ethylene carbonate (EC) was injected. The proportion of MEC in the mixed solvent was 70% by volume, and the proportion of EC was 30% by volume.
The outer container containing the electrolytic solution was sealed under a reduced pressure environment of −90 kPa. After the injection, the initial charge was performed at 1C (10A) to a state of charge (SOC) of 80%, and aging was performed for 24 hours in a constant temperature bath at 70 ° C. After aging, the can was opened and sealed again in a reduced pressure environment of −90 kPa to prepare a non-aqueous electrolyte battery.
(Examples 2 to 12)
Tables 1 to 3 show the weight ratios of the first positive electrode active material, the second positive electrode active material, the first and second positive electrode active materials, the density of each of the positive electrode and the negative electrode, the texture on one side, the thickness, and the Co / Ti weight ratio. A non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that the settings were as shown in.
(Example 13)
_{As a non-aqueous electrolyte, 1 mol / L LiPF 6} (first electrolyte) and 0.1 mol / L LiBF ₄ (second electrolyte) were dissolved in a mixed solvent of ethyl methyl carbonate (MEC) and ethylene carbonate (EC). An electrolyte was prepared. The proportion of MEC in the mixed solvent was 70% by volume, and the proportion of EC was 30% by volume.

Using the above non-aqueous electrolyte, the weight ratios of the first positive electrode active material, the second positive electrode active material, the first and second positive electrode active materials, the density and one-sided texture and thickness of each of the positive electrode and the negative electrode, and the Co / Ti weight. A non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that the ratio was set as shown in Tables 1 to 3.
(Examples 14 to 16)
Weight ratio of 1st positive electrode active material, 2nd positive electrode active material, 1st and 2nd positive electrode active materials, density and one-sided texture and thickness of each of positive electrode and negative electrode, type and concentration of second electrolyte of non-aqueous electrolyte , A non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that the Co / Ti weight ratio was set as shown in Tables 1 to 3.
(Example 17)
The type of negative electrode active material _{was changed to an oblique crystal type lithium titanium-containing oxide represented by Li 2} Na _1.5 Ti _5.5 Nb _0.5 O ₁₄ , and the first positive electrode active material and the second positive electrode active material were changed. Tables 1 to 1 show the weight ratio of the substance, the first and second positive electrode active materials, the density and one-sided texture and thickness of each of the positive electrode and the negative electrode, the type and concentration of the second electrolyte of the non-aqueous electrolyte, and the Co / Ti weight ratio. A non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that the settings were as shown in Table 3.
(Comparative Example 1)
Example 1 except that the density, the basis weight and thickness of one side, and the Co / Ti weight ratio are set as shown in Tables 1 to 3 for each of the positive electrode and the negative electrode without using the second positive electrode active material and the second electrolyte. A non-aqueous electrolyte battery was produced in the same manner as in the above.
(Comparative Example 2)
Weight ratio of 1st positive electrode active material, 2nd positive electrode active material, 1st and 2nd positive electrode active materials, density and one-sided texture and thickness of each of positive electrode and negative electrode, type and concentration of second electrolyte of non-aqueous electrolyte , A non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that the Co / Ti weight ratio was set as shown in Tables 1 to 3.
<Cycle characterization>
A 1C constant current charge / discharge cycle was carried out in a voltage range of 1.8V to 2.8V in a 45 ° C. environment. The capacity retention rate after 3000 cycles is shown in Table 3 below.
<Open circuit voltage of positive electrode>
^{The open circuit voltage V (vs. Li /} Li +) of the positive electrode when the non-aqueous electrolyte battery was discharged to 1.8 V at 0.2 C was measured by the above method, and the results are shown in Table 3.

As shown in Tables 1 to 3, the batteries of Examples 1 to 17 have a capacity retention rate of 0.005 ≦ (G _Co / S _Co ) / (G _Ti / S _Ti ) ≦ 0.15 after 3000 cycles. It is higher than that of Comparative Examples 1 and 2 which do not satisfy. Examples 1 to 11, 13 to 17 having a positive electrode thickness of 100 μm or less have a higher capacity retention rate after 3000 cycles than Example 12 having a positive electrode thickness of more than 100 μm. Further, by comparing Example 4 and Examples 13 to 15 having the same value of _{(G Co} / S _Co ) / (G _Ti / S _{Ti), it is advantageous for cycle performance to use the second electrolyte.} It turns out that there is. On the other hand, _{by comparing Example 1 and Example 17 having the same value of (G Co} / S _Co ) / (G _Ti / S _Ti ), Example 1 using lithium titanate as the negative electrode active material was carried out. It can be seen that the cycle performance is superior to that of Example 17.

Since the non-aqueous electrolyte battery according to at least one embodiment and the above-described embodiment _{satisfies 0.005 ≦ (G Co} / S _Co ) / (G _Ti / S _Ti ) ≦ 0.15, the positive electrode is excessive. It is possible to suppress discharge and improve the charge / discharge cycle life.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Electrode group, 2 ... Negative electrode, 2a ... Negative electrode current collector, 2b ... Negative electrode active material-containing layer, 3 ... Positive electrode, 3a ... Positive electrode current collector, 3b ... Positive electrode active material-containing layer, 3c ... Positive electrode current collector tab, 4 ... Separator, 5 ... Negative electrode terminal, 6 ... Positive electrode terminal, 7 ... Exterior member, 15 ... Negative electrode terminal, 15a ... Negative electrode lead, 16 ... Positive electrode terminal, 16a ... Positive electrode lead, 17a ... Metal container, 17b ... Seal plate, 17c ... Insulation member, 20 ... Battery pack, 23 ... Assembly battery, 24 ... Printed wiring board, 25 ... Thermista, 26 ... Protection circuit, 27 ... Energizing terminal, 28 ... Positive electrode side lead, 30 ... Negative electrode side lead, 36 ... Protective sheet, 37 ... storage container, 38 ... lid.

Claims (6)

A positive electrode active material containing a lithium-containing manganese oxide and a lithium-containing nickel cobalt manganese oxide is provided, and the content of the lithium-containing nickel cobalt manganese oxide in the positive electrode active material is 3 wt% or more and 20 wt% or less. A positive electrode containing a layer and
Negative electrode containing lithium titanium-containing oxide Negative electrode containing active material-containing layer and
A non-aqueous electrolyte battery containing a non-aqueous electrolyte and satisfying the following equation (1).
0.005 ≤ (G _Co / S _Co ) / (G _Ti / S _Ti ) ≤ 0.15 (1)
However, G _Co is the Co weight (mg) contained in the positive electrode active material-containing layer, S _Co is the area of the positive electrode active material-containing layer (cm ² ), and G _Ti is contained in the negative electrode active material-containing layer. Ti weight (mg) and ST _Ti ^{are the areas (cm 2} ) of the negative electrode active material-containing layer. When the non-aqueous electrolyte battery is discharged to 1.8 V at 0.2 C, the open circuit voltage of the positive electrode is 3.6 V (vs.Li ^/ Li +) or more and 3.9 ^{V (vs.Li / Li +} ) or less. The non-aqueous electrolyte battery according to claim 1. The non-aqueous electrolyte battery according to claim 1 or 2, wherein the thickness of the positive electrode is 100 μm or less. The non-aqueous electrolyte battery according to any one of claims 1 to 3, wherein the density of the positive electrode is 2.5 g / cc or more and 3.1 g / cc or less. The non-aqueous electrolyte battery according to any one of claims 1 to 4, which satisfies the following formula (2).
0.9 ≤ A / B ≤ 1.1 (2)
However, the charge capacity per unit area when A charge and discharge range of the positive electrode is not more than 3.0V (vs.Li/Li ⁺⁾ or ^{4.25V (vs.Li/Li +) (mAh /} m 2 ), And B is the charge capacity (mAh /) per unit area when the charge / discharge range of the negative electrode is 1.4 ^{V (vs.Li / Li +} ) or more and 2.0 V (vs.Li / Li +) or less. m ² ). A battery pack comprising the non-aqueous electrolyte battery according to any one of claims 1 to 5.

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