JP6892285B2 - Non-aqueous electrolyte battery - Google Patents

Description

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

In the production of non-aqueous electrolyte batteries, the cost of non-aqueous electrolyte solution accounts for a large proportion of the material cost of the battery. Therefore, it is desired to reduce the volume of the non-aqueous electrolytic solution. However, if the volume of the non-aqueous electrolyte solution is reduced too much, the input / output characteristics may be deteriorated. Further, if the volume of the non-aqueous electrolyte solution is reduced too much, the heat dissipation property of the non-aqueous electrolyte battery deteriorates, the temperature rise at the time of overcharging becomes large, and there is a problem that thermal runaway is likely to occur. This problem needs to be improved because it increases the risk, especially in batteries with high energy density.

Japanese Unexamined Patent Publication No. 2012-38702 JP-A-2007-220455 Japanese Unexamined Patent Publication No. 2005-183116 Japanese Unexamined Patent Publication No. 2000-1736662

It is an object of the present invention to provide a non-aqueous electrolyte battery capable of exhibiting high volumetric energy density and excellent safety.

According to embodiments, non-aqueous electrolyte batteries are provided. The non-aqueous electrolyte battery includes a container, a group of electrodes housed in the container, and a non-aqueous electrolyte solution housed in the container. The container is equipped with a gas release mechanism. The electrode group includes a negative electrode containing lithium titanate and a positive electrode. The non-aqueous electrolytic solution contains a solvent having a boiling point in the range of 85 ° C. or higher and 130 ° C. or lower. The non-aqueous electrolyte battery according to the embodiment has a volumetric energy density of 100 Wh / L or more. The non-aqueous electrolyte battery according to the embodiment has a ratio A / B and a ratio B / C within the following ranges:
0.55 ≤ A / B ≤ 0.7: (1);
1.2 ≦ B / C ≦ 1.35: (2).
here,
^{A is the volume [cm 3} ] of the voids in the container excluding the voids of the electrode group.
B is the volume [cm ³ ] of the non-aqueous electrolyte solution.
C is the volume [cm ³ ] of the voids of the electrode group.

FIG. 1 is a schematic exploded perspective view of an example non-aqueous electrolyte battery according to the embodiment. FIG. 2 is an enlarged cross-sectional view of part II of FIG.

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 explaining the embodiment and promoting its understanding, and the shape, dimensions, ratio, etc. of the figure are different from those of the actual device. The design can be changed as appropriate by taking into consideration.

(Embodiment)
According to embodiments, non-aqueous electrolyte batteries are provided. The non-aqueous electrolyte battery includes a container, a group of electrodes housed in the container, and a non-aqueous electrolyte solution housed in the container. The container is equipped with a gas release mechanism. The electrode group includes a negative electrode containing lithium titanate and a positive electrode. The non-aqueous electrolytic solution contains a solvent having a boiling point in the range of 85 ° C. or higher and 130 ° C. or lower. The non-aqueous electrolyte battery according to the embodiment has a ratio A / B and a ratio B / C within the following ranges:
0.55 ≤ A / B ≤ 0.7: (1);
1.2 ≦ B / C ≦ 1.35: (2).
here,
^{A is the volume [cm 3} ] of the voids in the container excluding the voids of the electrode group.
B is the volume [cm ³ ] of the non-aqueous electrolyte solution.
C is the volume [cm ³ ] of the voids of the electrode group.

The non-aqueous electrolyte battery according to the embodiment contains an amount of the non-aqueous electrolyte solution capable of exhibiting a high volumetric energy density for the reason described below, but is gas before the thermal runaway or the battery swelling occurs. Gas can be discharged from the inside of the container through the opening mechanism. As a result, the non-aqueous electrolyte battery according to the embodiment can exhibit high volumetric energy density and excellent safety.

First, the non-aqueous electrolyte solution contained in the non-aqueous electrolyte battery according to the embodiment contains a solvent having a boiling point in the range of 85 ° C. or higher and 130 ° C. or lower. By containing such a non-aqueous electrolyte solution, the non-aqueous electrolyte battery according to the embodiment vaporizes the solvent contained in the non-aqueous electrolyte solution before reaching the temperature at which thermal runaway occurs or before the battery swells. The heat of vaporization at that time can suppress the temperature rise of the non-aqueous electrolyte battery.

Further, in the non-aqueous electrolyte battery according to the embodiment, the ratio A / B is in the range of 0.55 or more and 0.7 or less, and the ratio B / C is in the range of 1.2 or more and 1.35 or less.

Here, the ratio B / C is the ratio of the volume B of the non-aqueous electrolyte solution to the volume C of the voids of the electrode group. In other words, the ratio B / C is the ratio of the amount of the non-aqueous electrolyte solution contained in the non-aqueous electrolyte battery to the volume of the voids of the electrode group that can be impregnated with the non-aqueous electrolyte solution. In the non-aqueous electrolyte battery according to the embodiment in which the ratio B / C is in the range of 1.2 or more and 1.35 or less, the volume of the non-aqueous electrolyte solution is the void of the electrode group including the negative electrode containing lithium titanate. Not excessive with respect to volume. Non-aqueous electrolyte batteries containing an excess of non-aqueous electrolyte show a low volumetric energy density. On the other hand, the non-aqueous electrolyte battery according to the embodiment can exhibit a high volumetric energy density because the volume of the non-aqueous electrolyte solution is not excessive. Further, the non-aqueous electrolyte battery according to the embodiment having a ratio B / C in the range of 1.2 or more and 1.35 or less is a non-aqueous electrolyte solution in an amount sufficient to exhibit excellent input / output characteristics. including. Further, the non-aqueous electrolyte battery according to the embodiment having a ratio B / C in the range of 1.2 or more and 1.35 or less can also exhibit excellent heat dissipation.

The ratio A / B is the ratio of the volume A of the voids in the container excluding the voids of the electrode group to the volume B of the non-aqueous electrolytic solution. On the other side, the volume A is the volume obtained by subtracting the volume occupied by the electrode group, the non-aqueous electrolyte solution, and other members from the internal volume of the container. The volume A is, on the other side, the volume of the gap in the container. That is, the ratio A / B is the ratio of the size of the space in which the volatile component of the non-aqueous electrolyte solution, for example, the non-aqueous solvent can be vaporized and diffused, to the amount of the non-aqueous electrolyte solution contained in the non-aqueous electrolyte battery. ..

The non-aqueous electrolyte battery according to the embodiment has a ratio A / B in the range of 0.55 or more and 0.7 or less and a ratio B / C in the range of 1.2 or more and 1.35 or less. Sufficient to increase the pressure inside the vessel to a pressure at which the gas release mechanism can be activated by vaporizing the amount of non-aqueous electrolyte solution indicated by the ratio B / C before reaching the temperature at which thermal runaway occurs or before battery swelling occurs. It can have a volume A.

As a result, the non-aqueous electrolyte battery according to the embodiment contains a gas in an amount capable of exhibiting a high energy density, but before reaching a temperature at which thermal runaway occurs or before battery swelling occurs. Gas can be discharged from the inside of the container through the opening mechanism. As a result, the non-aqueous electrolyte battery according to the embodiment can exhibit high volumetric energy density and excellent safety. In addition, the non-aqueous electrolyte battery according to the embodiment can also suppress battery swelling.

On the other hand, in a non-aqueous electrolyte battery in which the non-aqueous solvent of the non-aqueous electrolyte solution is a solvent having a boiling point of less than 80 ° C., even if the ratio A / B and the ratio B / C are within the above ranges, the temperature at which thermal runaway occurs. Even at a lower temperature or a temperature at which battery swelling cannot occur at all, the pressure inside the container increases, and gas is discharged from the inside of the container via the gas release mechanism. Such non-aqueous electrolyte batteries exhibit a low volumetric energy density due to the narrow range of chargeable states they can use. Further, such a non-aqueous electrolyte battery may not be put into practical use because it can emit gas even under normal use conditions.

Further, in a non-aqueous electrolyte battery in which the non-aqueous solvent of the non-aqueous electrolyte solution is a solvent having a boiling point higher than 130 ° C., the temperature rise cannot be suppressed by the vaporization of the non-aqueous solvent. Further, in such a non-aqueous electrolyte battery, even if the ratio A / B and the ratio B / C are within the above ranges, when the temperature of the battery rises, the pressure inside the container is such that the gas release mechanism can be operated. The pressure cannot be increased.

The volume ratio of the solvent having a boiling point in the range of 80 ° C. or higher and 130 ° C. or lower in the non-aqueous electrolytic solution is preferably 10% or more and 90% or less, and more preferably 50% or more and 80% or less. ..

Further, in a non-aqueous electrolyte battery in which the negative electrode does not contain lithium titanate, for example, a non-aqueous electrolyte battery in which a carbon material is used as the negative electrode active material in the negative electrode, the carbon material changes in volume, that is, expands as Li is inserted and removed. And contraction. Therefore, in such a non-aqueous electrolyte battery, it is necessary to include a large volume of the non-aqueous electrolyte solution with respect to the volume of the voids of the electrode group, for example, in order to prevent the electrode group from withering during the volume expansion of the negative electrode group. is there.

On the other hand, lithium titanate can show a small volume change or no volume change at both the insertion of Li at the time of charging the non-aqueous electrolyte battery and the desorption of Li at the time of discharging. Therefore, the non-aqueous electrolyte battery according to the embodiment can prevent liquid withering even if the ratio B / C of the volume B of the non-aqueous electrolyte solution to the volume C of the voids of the electrode group is 1.2 or more and 1.35 or less. it can.

When the ratio A / B is less than 0.55, it means that the space in which the solvent of the non-aqueous electrolyte can be vaporized and diffused is too small with respect to the amount of the electrolyte in the non-aqueous electrolyte battery. .. In such a non-aqueous electrolyte battery, the rate of increase in pressure inside the container when the solvent of the non-aqueous electrolyte solution is vaporized is too large. Therefore, in such a non-aqueous electrolyte battery, the pressure inside the container increases even at a temperature lower than the temperature at which thermal runaway occurs or at a temperature at which battery swelling cannot occur at all, and gas is discharged from the container via the gas release mechanism. To. Such non-aqueous electrolyte batteries exhibit a low volumetric energy density due to the narrow range of chargeable states they can use. Further, such a non-aqueous electrolyte battery may not be put into practical use because it can emit gas even under normal use conditions. Alternatively, in such a non-aqueous electrolyte battery, when the solvent of the non-aqueous electrolyte solution is vaporized, the container may swell before the gas is discharged from the gas release mechanism.

On the other hand, when the ratio A / B is larger than 0.7, the space in which the solvent of the non-aqueous electrolyte solution can be vaporized and diffused is too large for the amount of the electrolyte solution in the non-aqueous electrolyte battery. Point to. In such a non-aqueous electrolyte battery, the rate of increase in pressure inside the container when the solvent of the non-aqueous electrolyte solution is vaporized is too small. In such a non-aqueous electrolyte battery, when the temperature of the battery rises, the pressure inside the container cannot be increased to a pressure at which the gas release mechanism can be operated. Therefore, such a non-aqueous electrolyte battery may have an excessively high temperature, and has a safety problem such as a possibility of explosion.

The ratio A / B is preferably in the range of 0.55 or more and 0.7 or less, and more preferably in the range of 0.6 or more and 0.7 or less.

Further, in the non-aqueous electrolyte battery having a ratio B / C of less than 1.2, the volume of the non-aqueous electrolyte solution is too small, and it is not possible to sufficiently suppress the temperature rise due to the vaporization of the solvent of the non-aqueous electrolyte solution. .. Further, if the amount of the non-aqueous electrolytic solution is too small, the distribution of the electrolytic solution is biased in the electrode group. The bias in the distribution of the electrolytic solution causes a bias in the usage rate in the electrode group, which in turn causes local deterioration of the electrode group. Therefore, such a non-aqueous electrolyte battery is inferior in life characteristics. On the other hand, when the ratio B / C is larger than 1.35 and the ratio A / B is 0.55 or more, the volume of the voids of the electrode group is too small with respect to the volume of the non-aqueous electrolytic solution. In this case, it is not possible to show a high volumetric energy density. Alternatively, when the ratio B / C is larger than 1.35 and the ratio A / B is less than 0.55, the volume of the non-aqueous electrolytic solution is too large with respect to the volume of the voids of the electrode group. In such a non-aqueous electrolyte battery, the battery may swell due to the vaporization of the non-aqueous electrolyte solution.

The ratio B / C is preferably in the range of 1.2 or more and 1.35 or less, and more preferably in the range of 1.2 or more and 1.3 or less.

Next, the non-aqueous electrolyte battery according to the embodiment will be described in more detail.

The non-aqueous electrolyte battery according to the embodiment includes a container, an electrode group, and a non-aqueous electrolyte solution. The container contains a group of electrodes and a non-aqueous electrolyte solution.

The container is equipped with a gas release mechanism. The gas release mechanism can form an opening when the pressure inside the container rises until it reaches a predetermined design value, and can discharge the gas inside the container. Then, the gas release mechanism can reduce the pressure inside the container by discharging the gas inside the container. The gas release mechanism will be described later.

The electrode group includes a negative electrode and a positive electrode. The electrode group may also include a separator located between the negative electrode and the positive electrode. The voids of the electrode group can include, for example, the voids of the negative electrode, the voids of the positive electrode, and the voids of the separator.

The negative electrode can include a negative electrode current collector and a negative electrode active material-containing layer formed on the negative electrode current collector.

The negative electrode current collector can have, for example, a band shape. The negative electrode current collector having a band-shaped shape can have two surfaces as its main surface. The negative electrode active material-containing layer may be formed on one surface of the negative electrode current collector, or may be formed on both surfaces. The negative electrode current collector may also include a portion that does not support the negative electrode active material-containing layer. This portion can serve as a negative electrode current collector tab.

The negative electrode active material-containing layer can contain a negative electrode active material and, if necessary, a conductive agent and a binder. Lithium titanate can be contained in the negative electrode active material-containing layer as at least a part of the negative electrode active material. Further, the negative electrode active material-containing layer may contain voids. These voids can be, for example, voids formed by particles of the negative electrode active material, particles of the conductive agent, and particles of the binder.

The positive electrode can include a positive electrode current collector and a positive electrode active material-containing layer formed on the positive electrode current collector.

The positive electrode current collector can have, for example, a strip-shaped form. The positive electrode current collector having a band-shaped shape can have two surfaces as its main surface. The positive electrode active material-containing layer may be formed on one surface of the positive electrode current collector, or may be formed on both surfaces. The positive electrode current collector may also include a portion that does not support the positive electrode active material-containing layer. This portion can serve as a positive electrode current collector tab.

The positive electrode active material-containing layer can contain a positive electrode active material and, if necessary, a conductive agent and a binder. Further, the positive electrode active material-containing layer may contain voids. These voids can be, for example, voids formed by particles of the positive electrode active material, particles of the conductive agent, and particles of the binder.

The separator can be located, for example, between the positive electrode active material-containing layer and the negative electrode active material-containing layer. The separator may be porous. That is, the separator may also include voids.

In the electrode group including the negative electrode, the positive electrode, and the separator, a part of the negative electrode and a part of the positive electrode may at least face each other. Therefore, the electrode group may be a laminated type or a wound type. In the laminated electrode group, a plurality of positive electrodes and a plurality of negative electrodes are alternately laminated with a separator sandwiched between them. The winding type electrode group has a structure in which a positive electrode and a negative electrode are laminated with a separator sandwiched between them, and the laminated body thus obtained is spirally wound.

Further, the non-aqueous electrolyte battery according to the embodiment can further include a lead electrically connected to the electrode group. For example, the non-aqueous electrolyte battery according to the embodiment can also include two leads. One lead can be electrically connected to the positive electrode current collector tab. The other lead can be electrically connected to the negative electrode current collector tab.

The non-aqueous electrolyte battery according to the embodiment may further include a terminal that is electrically connected to the lead and is drawn out of the container. For example, the non-aqueous electrolyte battery according to the embodiment can be provided with two terminals. One terminal can be connected to a lead electrically connected to the positive electrode current collector tab. The other terminal can be connected to a lead electrically connected to the negative electrode current collector tab.

Alternatively, one terminal can be directly connected to the positive electrode current collecting tab, and the other terminal can be directly connected to the negative electrode current collecting tab. That is, in the non-aqueous electrolyte battery according to the embodiment, the lead may be omitted.

The non-aqueous electrolyte battery according to the embodiment may exhibit a volumetric energy density of 100 Wh / l or more. Even in the non-aqueous electrolyte battery of the embodiment having such a high volume energy density, the non-aqueous electrolyte battery according to the embodiment causes the battery to swell before reaching the temperature at which thermal runaway occurs or due to the reason described above. Before, the gas can be discharged from the container through the gas release mechanism, which can show excellent safety. The volumetric energy density is preferably in the range of 200 Wh / l or less, and more preferably in the range of 150 Wh / l or less.

Next, each component that can be provided in the non-aqueous electrolyte battery according to the embodiment will be described in more detail.

(1) Negative electrode Lithium titanate contained in the negative electrode has a property of increasing resistance at the time of discharge, and it is difficult for a large current to flow even if a minute short circuit occurs. Therefore, even if the positive electrode and the negative electrode are short-circuited, lithium titanate can be instantly discharged, and thus can act as an insulating material. Lithium titanate, which acts as an insulating material, can prevent further short-circuit currents from flowing. Further, as described above, lithium titanate can exhibit a small volume change at both the insertion of Li at the time of charging the non-aqueous electrolyte battery and the removal of Li at the time of discharging. Or there is no volume change. Therefore, lithium titanate can prevent deterioration due to repeated charging and discharging, and can realize excellent life performance.

Examples of lithium titanate contained in the negative electrode include lithium titanate Li _{4 + x} Ti ₅ O ₁₂ (0 ≦ x ≦ 3) having a spinel-type crystal structure.

The negative electrode active material-containing layer can contain a negative electrode active material other than lithium titanate. Examples of the negative electrode active material other than lithium titanate include monoclinic niobium titanium composite oxide, rutile type titanium dioxide (TiO ₂ ), anatase type titanium dioxide (TiO ₂ ), bronze type titanium dioxide (TiO ₂ ), and An oblique crystal type Na-containing niobium titanium composite oxide can be mentioned. It is preferable that 80% by mass or more and 100% by mass or less of the negative electrode active material is lithium titanate, and more preferably 90% by mass or more and 100% by mass or less.

The negative electrode active material may be primary particles and / or secondary particles formed by aggregating primary particles. The average particle size of the primary particles of the negative electrode active material is preferably in the range of 0.001 to 1 μm.

The negative electrode layer can further contain a conductive agent and a binder, if necessary.

The conductive agent is blended as necessary in order to improve the current collecting performance and suppress the contact resistance between the negative electrode active material and the negative electrode current collector. Examples of the conductive agent include acetylene black, carbon black, graphite, graphite and the like.

The binder can bind the negative electrode active material and the negative electrode current collector. Examples of the binder include polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF).

The blending amounts of the negative electrode active material, the conductive agent and the binder in the negative electrode active material-containing layer are 80% by mass or more and 98% by mass or less, 1% by mass or more and 10% by mass or less, and 1% by mass or more and 10% by mass or less, respectively. It is preferable to have.

The porosity of the negative electrode active material-containing layer is preferably 10% or more and 50% or less, and more preferably 20% or more and 40% or less, based on the apparent volume of the negative electrode active material-containing layer. The void ratio of the negative electrode active material-containing layer is, for example, adjusting the press load on the electrode when manufacturing the negative electrode, and adjusting the particle size of the negative electrode active material particles, the conductive agent particles, and the binder particles. It can be controlled by such as.

The negative electrode active material-containing layer can be formed, for example, by applying a slurry containing a negative electrode active material, a conductive agent, and a binder onto the negative electrode current collector and drying the slurry.

As the negative electrode current collector, for example, a metal foil such as aluminum or copper can be used.

(2) Positive electrode The positive electrode active material-containing layer can contain a positive electrode active material that can be charged and discharged in combination with lithium titanate contained in the negative electrode. Further, the positive electrode active material-containing layer may further contain a conductive agent and a binder in addition to the positive electrode active material, if necessary.

As the positive electrode active material, for example, a lithium transition metal composite oxide can be used. Examples of lithium transition metal composite oxides include, for example, Li _a CoO ₂ , Li _a Ni _1-x Co _x O ₂ (0 <x ≦ 0.5), and Li _a Mn _x Ni _y Co _z O ₂ (0). <X ≦ 0.5, 0 <y ≦ 0.5, 0 <z ≦ 0.5), Li _a Mn _2-x M _x O ₄ (M is Li, Mg, Co, Al and / or Ni. , 0 <x ≦ 0.2), Li _a MPO ₄ (M is Fe, Co and / or Ni) and the like. In the above general formula, the value of the subscript a changes in the range of 0 <a <1.5 depending on the charge / discharge state of each composite oxide.

The conductive agent is blended as necessary in order to improve the current collecting performance and suppress the contact resistance between the positive electrode active material and the positive electrode current collector. Examples of the conductive agent include acetylene black, carbon black, graphite, graphite and the like.

The binder can bind the positive electrode active material and the conductive agent. Examples of the binder include polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF).

The positive electrode active material-containing layer can be formed, for example, by applying a slurry containing a positive electrode active material, a conductive agent, and a binder onto the positive electrode current collector and drying the slurry.

As the positive electrode current collector, for example, a metal foil such as aluminum can be used.

The blending amounts of the positive electrode active material, the conductive agent and the binder in the positive electrode active material-containing layer are 80% by mass or more and 98% by mass or less, 1% by mass or more and 10% by mass or less, and 1% by mass or more and 10% by mass or less, respectively. It is preferable to have.

The porosity of the positive electrode active material-containing layer is preferably 10% or more and 50% or less, and more preferably 20% or more and 40% or less, based on the apparent volume of the positive electrode active material-containing layer. The void ratio of the positive electrode active material-containing layer is controlled by, for example, adjusting the press load on the electrode during the production of the positive electrode, and the particle size of the positive electrode active material particles, the conductive agent particles, and the binder particles. be able to.

(3) Separator The separator is made of an insulating material and can prevent electrical contact between the negative electrode and the positive electrode. Preferably, the separator is made of a material through which the electrolyte can pass or has a shape through which the electrolyte can pass. Examples of the separator include a synthetic resin non-woven fabric, a polyethylene porous film, a polypropylene porous film, and a cellulosic separator.

The porosity of the separator is preferably 30% or more and 95% or less, and more preferably 50% or more and 90% or less with respect to the apparent volume of the separator. The porosity of the separator can be controlled by, for example, rolling.

(4) Non-aqueous electrolyte The non-aqueous electrolyte can contain a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Alternatively, the non-aqueous electrolyte may include a polymer dissolved in a non-aqueous solvent.
The non-aqueous solvent includes a solvent having a boiling point of 80 ° C. or higher and 130 ° C. or lower. Examples of such a solvent include diethyl carbonate (boiling point: 127 ° C.), ethyl methyl carbonate (boiling point: 107 ° C.), dimethyl carbonate (boiling point: 90 ° C.), ethyl propionate (boiling point: 99 ° C.), and the like. Examples thereof include propyl acetate (boiling point: 102 ° C.) and acetonitrile (boiling point: 82 ° C.). The boiling point is the boiling point at 1 atm. Preferably, the non-aqueous solvent comprises ethyl methyl carbonate. One of the above solvents may be used alone, or two or more of them may be used as a mixed solvent. The non-aqueous solvent preferably contains a solvent having a boiling point in the range of 100 ° C. to 120 ° C.

A solvent having a boiling point of 80 ° C. or higher and 130 ° C. or lower may be mixed with another solvent. That is, the non-aqueous electrolyte solution can also contain a mixed solvent of a solvent having a boiling point of 80 ° C. or higher and 130 ° C. or lower and another solvent. Examples of other solvents include propylene carbonate (boiling point: 240 ° C.) and ethylene carbonate (boiling point: 260 ° C.).

Electrolyte salts include LiPF ₆ , LiBF ₄ , Li (CF ₃ SO ₂ ) ₂ N (bistrifluoromethanesulfonylamide lithium; commonly known as LiTFSI), LiCF ₃ SO ₃ (commonly known as LiTFS), Li (C ₂ F ₅ SO ₂ ). ₂ N (bis pentafluoroethanesulfonyl amide lithium; called _{LiBETI), LiClO 4, LiAsF 6} , LiSbF 6, bisoxalato Lato lithium borate _{(LiB (C 2 O 4)} 2 ( known as LiBOB)), difluoro (tri-fluoro-2 -Oxide-2-trifluoro-methylpropionato (2-)-0,0) _{Lithium salts such as lithium borate (LiBF 2} (OCOC (CF ₃ ) ₂ ) (commonly known as LiBF ₂ (HHIB))) can be mentioned. .. These electrolyte salts may be used alone or in combination of two or more. In particular, it is preferable to use _{LiPF 6} or LiBF _4.

The electrolyte salt concentration is preferably in the range of 0.5 M or more and 3 M or less. Thereby, the performance when a high load current is passed can be improved.

In addition, the non-aqueous electrolyte can further contain additives. Examples of the additive include, but are not limited to, vinylene carbonate (VC), vinylene acetate (VA), vinylene butyrate, vinylene hexanate, vinylene crotonate, catechol carbonate, propane sultone and the like. The concentration of the additive is preferably in the range of 0.1% by weight or more and 3% by weight or less with respect to 100% by weight of the non-aqueous electrolyte. A more preferable range is 0.5% by weight or more and 1% by weight or less.

(5) Container The container is provided with a gas release mechanism. The gas release mechanism can release the gas to the outside of the battery when the pressure inside the container reaches a predetermined pressure.

The container can include, for example, a portion that can be cleaved when the pressure inside the container rises above the design value as a gas release mechanism.

Alternatively, the container can be opened when the pressure inside the container rises and reaches the design value to release the gas inside the container, and then closed when the pressure inside the container drops and reaches the design value to seal the container. A mechanism that can be stopped can also be included as a gas release mechanism.

The gas release mechanism can be, for example, a gas release valve, a safety valve, a pressure reducing valve, or a gas relief valve.

The operating pressure of the gas release mechanism can be, for example, 0.5 MPa or more and 1 MPa or less.

The container can also include, for example, a container body having an opening and a lid that closes the opening of the container body. In this case, the gas release mechanism may be provided in the container body or in the lid. Alternatively, the container may not include a lid.

As the container, for example, a metal container made of aluminum, an aluminum alloy, iron, stainless steel, or the like can be used. If the container is a metal container, the container can also act as one terminal.

The metal container can include, for example, a container body including an opening and a lid that closes the opening of the container body. The container body and the lid can be joined by welding, for example.

The metal container can include a portion of the wall thickness that is smaller than that of the other portion. This portion breaks when the gas pressure inside the battery becomes high, and the gas inside the battery can be released. That is, the metal container can include a portion that can operate as a gas release mechanism when the gas pressure inside the battery becomes higher than a predetermined pressure. This part can also be called a gas release valve or a safety valve. The gas release valve or the safety valve may be provided with a groove so as to be more easily broken. The gas release valve or the safety valve may be provided on the container body or the lid.

The wall thickness of the portion of the metal container other than the gas release mechanism is preferably 1.0 mm or less, and more preferably 0.5 mm or less.

The shape of the container can be various, such as a square type, a cylindrical type, a thin type, and a coin type, depending on the application.

(6) Lead The material of the lead is not particularly limited, but for example, the same material as the positive electrode current collector and the negative electrode current collector can be used. By using a lead made of the same material as the current collector, the contact resistance with the current collector can be suppressed.

(7) Terminal The material of the terminal is not particularly limited, but for example, the same material as the positive electrode current collector and the negative electrode current collector can be used.

Hereinafter, the non-aqueous electrolyte battery according to the embodiment will be described in more detail with reference to the drawings.

FIG. 1 is a schematic exploded perspective view of the non-aqueous electrolyte battery of the first example according to the embodiment. FIG. 2 is an enlarged cross-sectional view of part II of FIG.

The battery 100 shown in FIGS. 1 and 2 is a sealed square non-aqueous electrolyte battery. The non-aqueous electrolyte battery 100 includes an outer can 1, a lid 2, a positive electrode external terminal 3, a negative electrode external terminal 4, and an electrode group 5. The outer can 1 and the lid 2 form a container.

The outer can 1 has a bottomed square cylinder shape, and is formed of, for example, a metal such as aluminum, an aluminum alloy, iron, or stainless steel.

As shown in FIG. 2, in the flat electrode group 5, the positive electrode 6 and the negative electrode 7 are wound in a flat shape with a separator 8 interposed therebetween. The positive electrode 6 includes, for example, a band-shaped positive electrode current collector 6c made of a metal foil, a positive electrode current collector tab 6a having one end parallel to the long side of the positive electrode current collector 6c, and a positive electrode current collector 6c among the positive electrode current collectors 6c. The positive electrode active material-containing layer 6b formed on the surface of the portion excluding the tab 6a is included. On the other hand, the negative electrode 7 includes, for example, a band-shaped negative electrode current collector 7c made of a metal foil, a negative electrode current collector tab 7a having one end parallel to the long side of the negative electrode current collector 7c, and a negative electrode among the negative electrode current collectors 7c. The negative electrode active material-containing layer 7b formed on the surface of the portion excluding the current collecting tab 7a is included.

In such a positive electrode 6, a separator 8 and a negative electrode 7, the positive electrode current collecting tab 6a protrudes from the separator 8 in the winding axis direction of the electrode group 5, and the negative electrode current collecting tab 7a protrudes from the separator 8 in the opposite direction. The positive electrode 6 and the negative electrode 7 are wound so as to be displaced from each other. As a result of such winding, as shown in FIG. 1, the positive electrode current collecting tab 6a spirally wound from one end face protrudes from the electrode group 5, and the electrode group 5 is spirally wound from the other end face. The negative electrode current collecting tab 7a protrudes. A non-aqueous electrolytic solution (not shown) is impregnated in the electrode group 5.

The positive electrode lead 10 has a support plate 10a, a through hole 10b opened in the support plate 10a, and current collecting portions 10c and 10d that are bifurcated from the support plate 10a and extend downward. On the other hand, the negative electrode lead 11 has a support plate 11a, a through hole 11b opened in the support plate 11a, and current collecting portions 11c and 11d that are bifurcated from the support plate 11a and extend downward.

The current collectors 10c and 10d are arranged so as to be in contact with the positive electrode current collector tab 6a. The positive electrode 6 of the electrode group 5 and the positive electrode lead 10 are electrically connected via the positive electrode current collecting tab 6a.

The current collectors 11c and 11d are arranged so as to be in contact with the negative electrode current collector tab 7a. The negative electrode 7 and the negative electrode lead 11 of the electrode group 5 are electrically connected via the negative electrode current collecting tab 7a.

Such a positive electrode lead 10 and a negative electrode lead 11 are attached to a rectangular lid 2. Further, as shown in FIG. 1, the positive electrode external terminal 3 and the negative electrode external terminal 4 are also further attached to the lid 2. The positive electrode lead 10 and the positive electrode external terminal 3 are electrically connected. Therefore, the material of the positive electrode lead 10 is not particularly specified, but it is desirable that the material is the same as that of the positive electrode external terminal 3. Similarly, the negative electrode lead 11 and the negative electrode external terminal 4 are electrically connected. Therefore, the material of the negative electrode lead 11 is not particularly specified, but it is desirable that the material is the same as that of the negative electrode external terminal 4. For example, aluminum or an aluminum alloy is used for the positive electrode external terminal 3, and for example, aluminum, aluminum alloy, copper, nickel, nickel-plated iron or the like is used for the negative electrode external terminal 4. For example, when the material of the external terminal is aluminum or an aluminum alloy, it is preferable that the material of the lead is aluminum or an aluminum alloy. When the external terminal is copper, it is desirable that the lead material is copper or the like.

An internal insulator 15 is arranged between the support plate 10a of the positive electrode lead 10 and the lid 2, and electrically insulates the positive electrode lead 10 and the lid 2. The internal insulator 15 includes a through hole 15a corresponding to the through hole 10b of the support plate 10a of the positive electrode lead 10. Further, an insulating gasket 14 is arranged between the positive electrode external terminal 3 and the lid 2, and electrically insulates the positive electrode external terminal 3 and the lid 2. Similarly, an internal insulator 15 is arranged between the support plate 11a of the negative electrode lead 11 and the lid 2, and electrically insulates the negative electrode lead 11 and the lid 2. The internal insulator 15 includes a through hole 15a corresponding to the through hole 11b of the support plate 11a of the negative electrode lead 11. Further, an insulating gasket 14 is arranged between the negative electrode external terminal 4 and the lid 2, and electrically insulates the negative electrode external terminal 4 and the lid 2.

It is desirable that the insulating gasket 14 and the internal insulator 15 are resin molded products.

The rectangular lid 2 is provided with a liquid injection hole 12. The liquid injection hole 12 is sealed with a sealing lid (not shown) after the non-aqueous electrolytic solution is injected into the outer can 1.

The safety valve 13 is composed of a cross groove 13b provided on the bottom surface of a rectangular recess 13a provided on the lid 2. Of the recesses 13a of the lid 2, the portion provided with the groove 13b is particularly thin. Therefore, the groove 13b can release the gas in the outer can 1 to the outside by breaking when the internal pressure of the outer can 1 rises and reaches a predetermined pressure. That is, the safety valve 13 can function as a gas release mechanism.

The lid 2 is seam-welded to the peripheral edge of the opening of the outer can 1, for example, by a laser. The lid 2 is formed of, for example, a metal such as aluminum, aluminum alloy, iron or stainless steel. It is desirable that the lid 2 and the outer can 1 are made of the same type of metal.

(Method for measuring the volume A of the void in the container and the volume B of the non-aqueous electrolyte solution)
First, a non-aqueous electrolyte battery to be measured is prepared. Next, the container of the non-aqueous electrolyte battery is opened. Weigh the opened non-aqueous electrolyte battery. Let the measured weight be a [g].

Next, in an environment of 25 ° C., ethyl methyl carbonate (EMC) is poured into the container of the non-aqueous electrolyte battery until the liquid is filled. Next, the weight of the non-aqueous electrolyte battery in this state is measured. Let the measured weight be b [g].

The difference (ba) [g] between the weight b and the weight a is the weight of the EMC poured. The amount of EMC poured corresponds to the voids in the container of the non-aqueous electrolyte battery. Since the specific gravity of EMC is 1.01 [g / cm ³ ], the volume A [cm ³ ] of the void in the container is calculated by (ba) [g] ÷ 1.01 [g / cm ^3]. ..

Next, the mixture of non-aqueous electrolyte and EMC is poured out from the container. Store the poured mixture. Next, the inside of the container of the non-aqueous electrolyte battery is subjected to drying at 100 ° C. for 24 hours in a state of accommodating the electrode group. After drying, weigh the non-aqueous electrolyte battery. Let the measured weight be c [g].

On the other hand, the specific gravity of the mixture of the non-aqueous electrolyte solution and the EMC stored earlier is measured. The measurement is performed according to the following procedure. First, a part of the mixture is taken and used as a sample. Weigh this sample. Let the measured weight be d [g]. Next, the volume of this sample is measured with a measuring cylinder. Let the measured volume be e [cm ³ ]. From the weight d and the volume e, the specific gravity of the mixture can be calculated as ^{(d / e) [g / cm 3].}

Next, the difference between the weight b and the weight c is calculated. This weight difference (bc) [g] is the weight of the mixture of the non-aqueous electrolyte solution and EMC. Next, the weight of the mixture (bc) [g] is divided by ^{the specific gravity (d / e) [g / cm 3] of the mixture.} The quotient {e (bc) / d} [cm ³ ] thus obtained is the volume of the mixture.

The volume of the mixture {e ( ^{bc) / d} [cm 3} ] and the volume of the injected EMC, that is, the volume of the void in the container A [cm ³ ] (= (ba) /1.01). The difference is the volume B [cm ³ ] of the non-aqueous electrolyte solution.

(Measurement of void volume C of electrode group)
^{The volume C [cm 3} ] of the voids of the electrode group is measured by the following procedure.

1. 1. Preparation of pore distribution sample First, a non-aqueous electrolyte battery to be measured is prepared. Next, the non-aqueous electrolyte battery is disassembled in an Ar atmosphere or a dry atmosphere with a dew point of −60 ° C. or lower, and the electrode group is taken out from the disassembled non-aqueous electrolyte battery.

The taken-out electrode group is disassembled into a positive electrode, a negative electrode, and a separator. Next, the apparent volume of the positive electrode active material-containing layer of the positive electrode, the apparent volume of the negative electrode active material-containing layer of the negative electrode, and the apparent volume of the separator are measured, respectively. Specifically, the apparent volume can be calculated by measuring the thickness using a micrometer and measuring the width and length using a tape measure and multiplying them.

Next, a test piece of a positive electrode having a substantially square planar shape having a planar shape of ^{20 to 30 cm 2} is cut out from the positive electrode active material-containing layer. Similarly, a negative electrode test piece and a separator test piece of the same size are cut out from the negative electrode active material-containing layer and the separator, respectively.

Each of the cut test pieces is ^{immersed in 100 cm 3} of ethyl methyl carbonate and left to stand for 5 minutes. After leaving, the test piece is taken out and dried for 1 day. Each dried test piece is subjected to pore distribution measurement.

Shimadzu Autopore 9520 type can be used as the pore distribution measuring device. Specifically, one test piece is cut into a size of about 25 mm width, folded, and taken in a standard cell. The measurement is performed under the condition of an initial pressure of 20 kPa (about 3 psia, equivalent to a pore diameter of about 60 μm). Thus, the pore distribution of each sample is obtained. In addition, the porosity of each sample can be obtained from the obtained pore distribution data.

(2) Derivation of void amount By multiplying the obtained porosity [%] by the previously measured apparent volume [cm ³ ], the void amounts of the positive electrode active material-containing layer, the negative electrode active material-containing layer, and the separator are respectively. Find [cm3]. The total amount of these voids is the volume C [cm ³ ] of the voids in the electrode group.

Specifically, the output void ratios are positive electrode test piece: o (%), negative electrode test piece: p (%), and separator: q (%), and the apparent volume measured earlier is the positive electrode active material. Assuming that the content layer: r [cm ³ ], the negative electrode active material-containing layer: s [cm ³ ], and the separator: t [cm ³ ], the volume C [cm ³ ] of the voids of the electrode group can be derived by the following equation. ..

C = r × o / 100 + s × p / 100 + t × q / 100

(Method of identifying non-aqueous electrolyte)
The non-aqueous electrolyte solution contained in the non-aqueous electrolyte battery is identified by the following procedure.
First, the electrolytic solution is extracted from the non-aqueous electrolyte battery to be measured. The extracted non-aqueous electrolyte solution is analyzed by gas chromatograph mass spectrometry and ion chromatography. By this analysis, each component (solvent and solute) contained in the non-aqueous electrolytic solution can be identified. In addition, each component can be quantified from the peak area of the chart obtained by this analysis. Calculate the ratio of each solvent from the quantitative value.

In addition, from the information of each component obtained from this analysis, the boiling point of each solvent can be known by using a database such as a chemical library and a Material Safety Data Sheet (MSDS). If it is not in the database, you can check the boiling point with a boiling point measuring device (for example, DosaTherm 300).

(Method of identifying negative electrode active material)
The negative electrode active material contained in the non-aqueous electrolyte battery can be identified using X-ray diffraction (XRD) measurement and inductively coupled plasma (ICP) emission spectroscopy.

The XRD measurement of the negative electrode active material contained in the non-aqueous electrolyte battery can be performed by the following procedure.

First, the non-aqueous electrolyte battery to be measured is put into a discharged state. Next, the battery is disassembled in a glove box filled with argon and the negative electrode is taken out. The removed negative electrode is washed with an appropriate solvent and dried under reduced pressure. For example, ethyl methyl carbonate and the like can be used. After washing and drying, check that there are no white precipitates such as lithium salts on the surface.

When used for powder X-ray diffraction measurement, the washed electrode is cut into an area substantially the same as the area of the holder of the powder X-ray diffractometer, and used as a measurement sample.

The obtained measurement sample is directly attached to the glass holder for measurement. At this time, the position of the peak derived from the electrode substrate such as the metal foil is measured in advance. In addition, peaks of other components such as conductive agents and binders are also measured in advance. When the peak of the substrate and the peak of the active material overlap, it is desirable to peel off the layer containing the active material (for example, the active material layer described later) from the substrate and use it for measurement. This is to separate overlapping peaks when quantitatively measuring the peak intensity. For example, the active material layer can be peeled off by irradiating the electrode substrate with ultrasonic waves in a solvent. The active material layer is sealed in a capillary and placed on a rotating sample table for measurement. By such a method, the XRD pattern of the active material can be obtained while reducing the influence of orientation.

As a device for measuring X-ray diffraction, a fully automatic multipurpose X-ray diffractometer SmartLab (RIGAKU) is used. The measurement is performed according to the θ / 2θ continuous measurement method under the conditions of an acceleration voltage of 40 kV, an acceleration current of 40 mA, and a scanning speed of 2.0 ° / min. When using other devices, measure using standard Si powder for X-ray diffraction so that the same measurement results as above can be obtained, and perform the measurement under the conditions that the peak intensity and peak top position match those of the above device. ..

To measure the composition of the negative electrode active material incorporated in the battery by ICP emission spectroscopy, the procedure is specifically as follows. First, according to the procedure described above, the negative electrode containing the active material to be measured is taken out from the non-aqueous electrolyte battery and washed. The washed negative electrode is placed in a suitable solvent and irradiated with ultrasonic waves. For example, the negative electrode active material layer containing the negative electrode active material can be peeled from the current collector by putting the electrode body in ethyl methyl carbonate put in a glass beaker and vibrating it in an ultrasonic cleaner. Next, vacuum drying is performed to dry the peeled negative electrode active material layer. By pulverizing the obtained electrode layer with a mortar or the like, a powder containing a target negative electrode active material, a conductive agent, a binder and the like can be obtained. By dissolving this powder with an acid, a liquid sample containing a negative electrode active material can be prepared. At this time, hydrochloric acid, nitric acid, sulfuric acid, hydrogen fluoride and the like can be used as the acid. By subjecting this liquid sample to ICP emission spectroscopic analysis, the composition of the negative electrode active material can be known.

From the obtained XRD pattern and composition information, the negative electrode active material can be identified based on a database, for example, JCPDS.

According to embodiments, non-aqueous electrolyte batteries are provided. The non-aqueous electrolyte battery includes a container, a group of electrodes housed in the container, and a non-aqueous electrolyte solution housed in the container. The container is equipped with a gas release mechanism. The non-aqueous electrolytic solution contains a solvent having a boiling point in the range of 85 ° C. or higher and 130 ° C. or lower. The non-aqueous electrolyte battery according to the embodiment has a ratio A / B and a ratio B / C within the following ranges: 0.55 ≦ A / B ≦ 0.7: (1); 1.2 ≦ B / C. ≦ 1.35: (2). Here, A is the volume of the voids in the container excluding the voids of the electrode group [cm ³ ], B is the volume of the non-aqueous electrolyte solution [cm ³ ], and C is the volume of the voids of the electrode group [cm 3]. cm ³ ]. Although this non-aqueous electrolyte battery contains an amount of non-aqueous electrolyte solution capable of exhibiting a high volumetric energy density, gas is released from the container through a gas release mechanism before a thermal runaway or a battery swelling occurs. Can be discharged. As a result, this non-aqueous electrolyte battery can exhibit high volumetric energy density and excellent safety.

[Example]
Hereinafter, the above-described embodiment will be described in more detail based on the examples.

(Example 1)
In Example 1, the non-aqueous electrolyte battery of Example 1 was produced by the following procedure.

<Preparation of positive electrode>
_{As a cathode active material, a powder of lithium manganate (LiMn 2} O ₄ : LMO) having a spinel-type crystal structure (average primary particle size: 10 μm) was prepared. Further, a powder of acetylene black (AB) (average primary particle size: 0.1 μm) was prepared as a conductive agent. In addition, polyvinylidene fluoride (PVdF) was prepared as a binder.

Next, the prepared material was charged into N-methyl-2-pyrrolidone (NMP) as a solvent so that the mass ratio of LMO: AB: PvdF was 90: 5: 5. The obtained mixture was stirred to obtain a positive electrode slurry.

Next, a band-shaped current collector made of aluminum foil having a thickness of 15 μm was prepared. A positive electrode slurry was applied on both surfaces of the current collector. At this time, a portion where the positive electrode slurry was not applied was left along one long side of the current collector. The basis weight of the slurry was set to 80 g / m ² . Then, the coating film was dried, and the dried coating film was applied to a press. Thus, a positive electrode including the positive electrode current collector and the positive electrode active material-containing layers formed on both sides of the positive electrode current collector was obtained. The positive electrode current collector included a positive electrode current collector tab that extended along one long side and did not carry a positive electrode active material-containing layer on its surface.

<Manufacturing of negative electrode>
As a negative electrode active material, _{a powder of lithium titanate (Li 4} Ti ₅ O ₁₂ : LTO) having a spinel-type crystal structure (average primary particle size: 1 μm) was prepared. In addition, graphite powder (average primary particle size: 5 μm) was prepared as a conductive agent. In addition, PVdF was prepared as a binder.

Next, the prepared material was put into NMP as a solvent so that the mass ratio of LTO: graphite: PvdF was 90: 5: 5. The obtained mixture was stirred to obtain a negative electrode slurry.

Next, a band-shaped current collector made of aluminum foil having a thickness of 15 μm was prepared. Negative electrode slurry was applied on both surfaces of the current collector. At this time, a portion where the negative electrode slurry was not applied was left along one long side of the current collector. The basis weight of the slurry was set to 40 g / m ² . Then, the coating film was dried, and the dried coating film was applied to a press. Thus, a negative electrode including the negative electrode current collector and the negative electrode active material-containing layers formed on both sides of the negative electrode current collector was obtained. The negative electrode current collector included a negative electrode current collector tab extending along one long side and not carrying a negative electrode active material-containing layer on the surface.

<Preparation of electrode group>
As the separator, two strip-shaped resin separators having a thickness of 15 μm were prepared.
Next, the negative electrode prepared earlier, one separator, the positive electrode prepared earlier, and the separator were laminated in this order to obtain a laminated body. At this time, the stacking position was adjusted so that the positive electrode current collecting tab did not face the negative electrode and the negative electrode current collecting tab did not face the positive electrode.

The obtained laminate was wound so that the negative electrode was on the outside. Next, the winding core was pulled out from the winding body, and the winding body was subjected to a press. Next, the parts other than the positive electrode current collecting tab and the negative electrode current collecting tab were covered with insulating tape. Thus, an electrode group having the same structure as the electrode group 5 shown in FIGS. 1 and 2 was obtained.

<Manufacturing of non-aqueous electrolyte battery unit>
Next, an outer can, a lid, a positive electrode lead, a negative electrode lead, a positive electrode external terminal, a negative electrode external terminal, an insulating gasket, and an internal insulator similar to those shown in FIG. 1 were prepared. The internal volume of the outer can was 235 cm ² . The outer can was equipped with the same safety valve as described with reference to FIG. The operating pressure of the safety valve was 0.7 MPa.

As described above, the lid, the positive electrode lead, the negative electrode lead, the positive electrode external terminal, the negative electrode external terminal, the insulating gasket, and the internal insulator are fixed by using the above-mentioned members prepared above and the electrode group prepared above. did. Next, the positive electrode lead was welded to the positive electrode current collecting tab of the electrode group. Similarly, the negative electrode lead was welded to the negative electrode current collecting tab of the electrode group. Next, the electrode group was housed in the outer can. Here, the electrode length was adjusted so that the total volume of the electrode group and each member in the outer can was 84% of the inner volume of the outer can. The lid was then welded to the periphery of the opening in the outer can. Thus, a non-aqueous electrolyte battery unit was produced.

<Adjustment of non-aqueous electrolyte solution>
Ethyl methyl carbonate (MEC; boiling point 107 ° C.) and ethylene carbonate (EC; boiling point 260 ° C.) were mixed at a volume ratio of 2: 1 to obtain a mixed solvent. _{Lithium hexafluorophosphate LiPF 6} was dissolved in this mixed solvent at a concentration of 1.0 mol / L to prepare a non-aqueous electrolytic solution.

<Completion of non-aqueous electrolyte battery>
Next, the previously prepared non-aqueous electrolyte battery unit was put into a dryer and vacuum dried at 95 ° C. for 6 hours. After drying, it was carried to a glove box controlled so that the dew point was -50 ° C or lower.

In the glove box, the previously prepared non-aqueous electrolytic solution was injected into the outer can. The injection volume B was 67 cm ³ . The outer can containing the non-aqueous electrolytic solution was sealed under a reduced pressure environment of −90 kPa.
Thus, the non-aqueous electrolyte battery of Example 1 was completed.

<Overcharge test>
The non-aqueous electrolyte battery of Example 1 was charged at 1C until fully charged. Next, the non-aqueous electrolyte battery of Example 1 was further overcharged to an SOC of 250% at 1C. The maximum temperature during the test was 140 ° C. and the safety valve was opened.

The hazard level of the non-aqueous electrolyte battery of Example 1 was HL3. This hazard level is based on the EUCAR (European Council for Automotive R & D). The criteria for determining the hazard level are shown in Table 1 below.

<Storage test>
The non-aqueous electrolyte battery of Example 1 was charged at 1C until fully charged. In this state, the thickness of the non-aqueous electrolyte of Example 1 was confirmed as the thickness before storage. The non-aqueous electrolyte battery of Example 1 was then stored at 65 ° C. for 50 days. After storage, the thickness of the non-aqueous electrolyte battery was confirmed as the thickness after storage. Here, the thickness of the non-aqueous electrolyte battery is the thickness at the center of the largest surface. As a result of the measurement, it was found that the thickness before storage was 21.2 mm and the thickness after storage was 21.5 mm. In addition, the inside of the outer can was in a depressurized state.

(Example 2)
In Example 2, the non-aqueous electrolyte battery of Example 2 was produced in the same procedure as in Example 1 except that the volume B of the non-aqueous electrolyte solution was 64 cm ^3.

The prepared non-aqueous electrolyte battery of Example 2 was subjected to an overcharge test in the same procedure as in Example 1. The maximum temperature during the overcharge test was 160 ° C. and the safety valve was opened. The hazard level was HL3.

Further, the non-aqueous electrolyte battery of Example 2 was subjected to a storage test in the same procedure as in Example 1. Further, similarly to Example 1, the thickness of the non-aqueous electrolyte battery of Example 2 before storage and the thickness after storage were confirmed. As a result of the measurement, it was found that the thickness before storage was 21.2 mm and the thickness after storage was 21.4 mm. In addition, the inside of the outer can was in a depressurized state.

(Example 3)
In Example 3, the non-aqueous electrolyte battery of Example 3 was produced in the same procedure as in Example 1 except that the volume B of the non-aqueous electrolyte solution was 61 cm ^3.

The prepared non-aqueous electrolyte battery of Example 3 was subjected to an overcharge test in the same procedure as in Example 1. The maximum temperature during the overcharge test was 160 ° C. and the safety valve was opened. The hazard level was HL3.

Further, the non-aqueous electrolyte battery of Example 3 was subjected to a storage test in the same procedure as in Example 1. Further, similarly to Example 1, the thickness of the non-aqueous electrolyte battery of Example 3 before storage and the thickness after storage were confirmed. As a result of the measurement, it was found that the thickness before storage was 21.2 mm and the thickness after storage was 21.4 mm. In addition, the inside of the outer can was in a depressurized state.

(Example 4)
In Example 4, as a mixed solvent of the non-aqueous electrolyte solution, a mixture of diethyl carbonate (DEC; boiling point: 127 ° C.) and ethylene carbonate (EC; boiling point: 260 ° C.) at a volume ratio of 2: 1 was used. The non-aqueous electrolyte battery of Example 4 was produced in the same procedure as in Example 1 except that the volume B of the non-aqueous electrolyte solution was 64 cm ^3.

The prepared non-aqueous electrolyte battery of Example 4 was subjected to an overcharge test in the same procedure as in Example 1. The maximum temperature during the overcharge test was 160 ° C. and the safety valve was opened. The hazard level was HL3.

Further, the non-aqueous electrolyte battery of Example 4 was subjected to a storage test in the same procedure as in Example 1. Further, similarly to Example 1, the thickness of the non-aqueous electrolyte battery of Example 4 before storage and the thickness after storage were confirmed. As a result of the measurement, it was found that the thickness before storage was 21.2 mm and the thickness after storage was 21.3 mm. In addition, the inside of the outer can was in a depressurized state.

(Example 5)
In Example 5, lithium cobalt oxide (LiCoO ₂ : LCO) powder (average primary particle size: 10 μm) was used as the positive electrode active material, and the prepared material had a mass ratio of LCO: AB: PvdF of 90: 5: 5. The non-aqueous electrolyte battery of Example 5 was produced in the same procedure as in Example 1 except that the positive electrode slurry was prepared by mixing as described above. As the acetylene black (AB) powder, the powder having an average primary particle size of 0.1 μm was used as in Example 1.

The prepared non-aqueous electrolyte battery of Example 5 was subjected to an overcharge test in the same procedure as in Example 1. The maximum temperature during the overcharge test was 150 ° C. and the safety valve was opened. The hazard level was HL3.

Further, the non-aqueous electrolyte battery of Example 5 was subjected to a storage test in the same procedure as in Example 1. After storage, the thickness of the non-aqueous electrolyte battery was confirmed. As a result of the measurement, it was found that the thickness before storage was 21.2 mm and the thickness after storage was 21.4 mm. In addition, the inside of the outer can was in a depressurized state.

(Example 6)
In Example 6, a powder of lithium nickel manganese cobalt oxide (LiMn _0.3 Ni _0.5 Co _0.2 O ₂ : NCM) (average primary particle size: 10 μm) was used as the positive electrode active material, and the prepared material was used as the mass of NCM: AB: PvdF. The non-aqueous electrolyte battery of Example 6 was prepared in the same procedure as in Example 1 except that the positive electrode slurry was prepared by mixing so that the ratio was 90: 5: 5. As the acetylene black (AB) powder, the powder having an average primary particle size of 0.1 μm was used as in Example 1.

The prepared non-aqueous electrolyte battery of Example 6 was subjected to an overcharge test in the same procedure as in Example 1. The maximum temperature during the overcharge test was 150 ° C. and the safety valve was opened. The hazard level was HL3.

Further, the non-aqueous electrolyte battery of Example 6 was subjected to a storage test in the same procedure as in Example 1. After storage, the thickness of the non-aqueous electrolyte battery was confirmed. As a result of the measurement, the thickness before storage was 21.2 mm, and the thickness after storage was 21.3 mm. In addition, the inside of the outer can was in a depressurized state.

(Example 7)
In Example 7, the same NCM used in Example 6 and the same LCO mixed powder used in Example 7 were used as the positive electrode active material, and the prepared material was NCM: LCO: AB: PvdF. The non-aqueous electrolyte battery of Example 6 was prepared in the same procedure as in Example 1 except that the positive electrode slurry was prepared by mixing so that the mass ratio of the above was 75:15: 5: 5. As the acetylene black (AB) powder, the powder having an average primary particle size of 0.1 μm was used as in Example 1.

The prepared non-aqueous electrolyte battery of Example 7 was subjected to an overcharge test in the same procedure as in Example 1. The maximum temperature during the overcharge test was 150 ° C. and the safety valve was opened. The hazard level was HL3.

Further, the non-aqueous electrolyte battery of Example 7 was subjected to a storage test in the same procedure as in Example 1. After storage, the thickness of the non-aqueous electrolyte battery was confirmed. As a result of the measurement, the thickness before storage was 21.2 mm, and the thickness after storage was 21.3 mm. In addition, the inside of the outer can was in a depressurized state.

(Example 8)
In Example 8, a mixed powder of LMO similar to that used in Example 1 and LCO similar to that used in Example 7 was used as the positive electrode active material, and the prepared material was LMO: LCO: AB: PvdF. The non-aqueous electrolyte battery of Example 8 was produced in the same procedure as in Example 1 except that the positive electrode slurry was prepared by mixing so that the mass ratio of the above was 75:15: 5: 5. As the acetylene black (AB) powder, the powder having an average primary particle size of 0.1 μm was used as in Example 1.

The prepared non-aqueous electrolyte battery of Example 8 was subjected to an overcharge test in the same procedure as in Example 1. The maximum temperature during the overcharge test was 140 ° C. and the safety valve was opened. The hazard level was HL3.

Further, the non-aqueous electrolyte battery of Example 8 was subjected to a storage test in the same procedure as in Example 1. After storage, the thickness of the non-aqueous electrolyte battery was confirmed. As a result of the measurement, the thickness before storage was 21.2 mm, and the thickness after storage was 21.4 mm. In addition, the inside of the outer can was in a depressurized state.

(Comparative Example 1)
In Comparative Example 1, the non-aqueous electrolyte battery of Comparative Example 1 was produced in the same procedure as in Example 1 except that the volume B of the non-aqueous electrolyte solution was 72 cm ^3.

The prepared non-aqueous electrolyte battery of Comparative Example 1 was subjected to an overcharge test in the same procedure as in Example 1. The maximum temperature during the overcharge test was 140 ° C. and the safety valve was opened. The hazard level was HL3.

Further, the non-aqueous electrolyte battery of Comparative Example 1 was subjected to a storage test in the same procedure as in Example 1. After storage, the thickness of the non-aqueous electrolyte battery was confirmed. As a result of the measurement, it was found that the thickness before storage was 21.2 mm and the thickness after storage was 24 mm. In addition, the inside of the outer can was in a positive pressure state.

(Comparative Example 2)
In Comparative Example 2, the non-aqueous electrolyte battery of Comparative Example 2 was produced in the same procedure as in Example 1 except that the volume B of the non-aqueous electrolyte solution was 59 cm ^3.

The prepared non-aqueous electrolyte battery of Comparative Example 2 was subjected to an overcharge test in the same procedure as in Example 1. The maximum temperature during the overcharge test was 300 ° C. and the safety valve was opened. The hazard level was HL4.

Further, the non-aqueous electrolyte battery of Comparative Example 2 was subjected to a storage test in the same procedure as in Example 1. After storage, the thickness of the non-aqueous electrolyte battery was confirmed. As a result of the measurement, it was found that the thickness before storage was 21.2 mm and the thickness after storage was 21.5 mm or less. In addition, the inside of the outer can was in a depressurized state.

(Comparative Example 3)
In Comparative Example 3, the non-aqueous electrolyte battery of Comparative Example 3 was produced in the same procedure as in Example 1 except that the volume B of the non-aqueous electrolyte solution was 54 cm ^3.

The prepared non-aqueous electrolyte battery of Comparative Example 3 was subjected to an overcharge test in the same procedure as in Example 1. The maximum temperature during the overcharge test was 300 ° C., and the hazard level at which the safety valve was opened was HL4.

Further, the non-aqueous electrolyte battery of Comparative Example 3 was subjected to a storage test in the same procedure as in Example 1. After storage, the thickness of the non-aqueous electrolyte battery was confirmed. As a result of the measurement, it was found that the thickness before storage was 21.2 mm and the thickness after storage was 21.8 mm. In addition, the inside of the outer can was in a depressurized state.

(Comparative Example 4)
In Comparative Example 4, the non-aqueous electrolyte battery of Comparative Example 4 was produced in the same procedure as in Example 1 except that the lengths of the positive electrode, the negative electrode, and the separator were each shorter than those in Example 1 by 8%.

The prepared non-aqueous electrolyte battery of Comparative Example 4 was subjected to an overcharge test in the same procedure as in Example 1. The maximum temperature during the overcharge test was 140 ° C. and the safety valve was opened. The hazard level was HL3.

Further, the non-aqueous electrolyte battery of Comparative Example 4 was subjected to a storage test in the same procedure as in Example 1. After storage, the thickness of the non-aqueous electrolyte battery was confirmed. As a result of the measurement, it was found that the thickness before storage was 20.5 mm and the thickness after storage was 20.6 mm. In addition, the inside of the outer can was in a depressurized state.

(Comparative Example 5)
In Comparative Example 5, the non-aqueous electrolyte battery of Comparative Example 5 was produced in the same procedure as in Example 1 except that the lengths of the positive electrode, the negative electrode, and the separator were each longer than those in Example 1 by 8%.

The prepared non-aqueous electrolyte battery of Comparative Example 5 was subjected to an overcharge test in the same procedure as in Example 1. The maximum temperature during the overcharge test was 300 ° C. and the safety valve was opened. The hazard level was HL4.

Further, the non-aqueous electrolyte battery of Comparative Example 5 was subjected to a storage test in the same procedure as in Example 1. After storage, the thickness of the non-aqueous electrolyte battery was confirmed. As a result of the measurement, it was found that the thickness before storage was 21.8 mm and the thickness after storage was 23.0 mm. In addition, the inside of the outer can was in a positive pressure state.

(Comparative Example 6)
In Comparative Example 6, the non-aqueous electrolyte battery of Comparative Example 6 was produced in the same procedure as in Comparative Example 4 except that the volume B of the non-aqueous electrolyte solution was 71 cm ^3.

The prepared non-aqueous electrolyte battery of Comparative Example 6 was subjected to an overcharge test in the same procedure as in Example 1. The maximum temperature during the overcharge test was 140 ° C. and the safety valve was opened. The hazard level was HL3.

Further, the non-aqueous electrolyte battery of Comparative Example 6 was subjected to a storage test in the same procedure as in Example 1. After storage, the thickness of the non-aqueous electrolyte battery was confirmed. As a result of the measurement, it was found that the thickness before storage was 20.5 mm and the thickness after storage was 20.6 mm. In addition, the inside of the outer can was in a depressurized state.

(Comparative Example 7)
In Comparative Example 7, the non-aqueous electrolyte battery of Comparative Example 7 was produced in the same procedure as in Comparative Example 5 except that the volume B of the non-aqueous electrolyte solution was set to 60 cm ^3.

The prepared non-aqueous electrolyte battery of Comparative Example 7 was subjected to an overcharge test in the same procedure as in Example 1. The maximum temperature during the overcharge test was 300 ° C. and the safety valve was opened. The hazard level was HL4.

Further, the non-aqueous electrolyte battery of Comparative Example 7 was subjected to a storage test in the same procedure as in Example 1. After storage, the thickness of the non-aqueous electrolyte battery was confirmed. As a result of the measurement, it was found that the thickness before storage was 21.8 mm and the thickness after storage was 25.0 mm. In addition, the inside of the outer can was in a positive pressure state.

<Various measurements>
(Volume energy density)
The volumetric energy density of each battery was calculated. The following formula was used for the calculation.
Volumetric energy density (Wh / L) = X × Y ÷ Z
Here, X is the nominal voltage (V) of the battery, Y is the nominal capacity (Ah) of the battery, and Z is the internal volume (L) of the outer can. The nominal voltage X was 2.4 V for all non-aqueous electrolyte batteries. The nominal capacity Y of the non-aqueous electrolyte batteries of Comparative Examples 4 and 6 is 10.8 Ah, the nominal capacity Y of the non-aqueous electrolyte batteries of Comparative Examples 5 and 7 is 12.7 Ah, and other non-aqueous electrolytes. The nominal capacity Y of the battery was 11.7 Ah.

(Measurement of void volume A in the container and void volume C of the electrode group)
The volume A of the voids in the container of each of the non-aqueous electrolyte batteries of Examples 1 to 4 and Comparative Examples 1 to 7 and the volume C of the voids of the electrode group were measured by the methods described above.

The various measurement results are shown in Table 2 below. Table 2 also shows the volume B of the non-aqueous electrolyte solution of each non-aqueous electrolyte battery and the non-aqueous solvent.

<Result>
From the results shown in Table 2, the non-aqueous electrolyte batteries of Examples 1 to 8 show a high volumetric energy density, have a hazard level of HL3 or less in the overcharge test, and suppress battery swelling in the 65 ° C. storage test. You can see that it was possible.

On the other hand, in the non-aqueous electrolyte battery of Comparative Example 1, the ratio A / B was less than 0.55 and the ratio B / C was larger than 1.35, so that the solvent of the non-aqueous electrolyte solution was vaporized inside the container. It is considered that the space that can be diffused was too small for the amount of the electrolytic solution in the non-aqueous electrolyte battery. Therefore, in the non-aqueous electrolyte battery of Comparative Example 1, the battery swelled in the 65 ° C. storage test.

Further, in the non-aqueous electrolyte batteries of Comparative Examples 2 and 3, the ratio A / B was larger than 0.7 and the ratio B / C was less than 1.2. It is considered that the space that can be transformed and diffused was too large for the amount of the electrolytic solution in the non-aqueous electrolyte battery. Therefore, in the non-aqueous electrolyte batteries of Comparative Examples 2 and 3, in the overcharge test, the temperature became too high before the valve was opened, and the safety was lowered (hazard level was high).

The non-aqueous electrolyte battery of Comparative Example 4 had a ratio A / B of more than 0.7, and the size of the electrode group with respect to the battery volume was small. Therefore, the non-aqueous electrolyte battery of Comparative Example 4 had a low volumetric energy density.

Since the non-aqueous electrolyte battery of Comparative Example 5 had a ratio A / B of less than 0.55, the space inside the container where the solvent of the non-aqueous electrolyte solution could be vaporized and diffused was the space of the electrolyte solution in the non-aqueous electrolyte battery. Probably too small for the amount. Therefore, in the non-aqueous electrolyte battery of Comparative Example 5, in the overcharge test, the temperature became too high before the valve was opened, and the safety was lowered (hazard level was high). Further, in the non-aqueous electrolyte battery of Comparative Example 5, the battery swelled in the 65 ° C. storage test for the above reason.

Since the non-aqueous electrolyte battery of Comparative Example 6 had a ratio B / C of more than 1.35 and a ratio of A / B of 0.55 or more, the volume of the voids in the electrode group was larger than the volume of the non-aqueous electrolyte solution. Is thought to have been too small. Therefore, the non-aqueous electrolyte battery of Comparative Example 6 had a low volumetric energy density.

It is considered that the non-aqueous electrolyte battery of Comparative Example 7 had a ratio B / C of less than 1.2, and the amount of the electrolytic solution was too small with respect to the volume of the voids of the electrode group. Therefore, in the non-aqueous electrolyte battery of Comparative Example 7, the electrolytic solution did not sufficiently spread in the electrode group, and excessive deterioration occurred locally, resulting in deterioration of storage characteristics and overcharge characteristics. Conceivable.

According to one or more embodiments or embodiments described above, a non-aqueous electrolyte battery is provided. The non-aqueous electrolyte battery includes a container, a group of electrodes housed in the container, and a non-aqueous electrolyte solution housed in the container. The container is equipped with a gas release mechanism. The electrode group contains voids. The non-aqueous electrolytic solution contains a solvent having a boiling point in the range of 85 ° C. or higher and 130 ° C. or lower. The non-aqueous electrolyte battery according to the embodiment has a ratio A / B and a ratio B / C within the following ranges: 0.55 ≦ A / B ≦ 0.7: (1); 1.2 ≦ B / C. ≦ 1.35: (2). Here, A is the volume of the voids in the container excluding the voids of the electrode group [cm ³ ], B is the volume of the non-aqueous electrolyte solution [cm ³ ], and C is the volume of the voids of the electrode group [cm 3]. cm ³ ]. Although this non-aqueous electrolyte battery contains an amount of non-aqueous electrolyte solution capable of exhibiting a high volumetric energy density, gas is released from the container through a gas release mechanism before a thermal runaway or a battery swelling occurs. Can be discharged. As a result, this non-aqueous electrolyte battery can exhibit high volumetric energy density and excellent safety.

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, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.
Hereinafter, the inventions described in the claims at the time of filing the application of the present application will be added.
[1] A container equipped with a gas release mechanism and
A group of electrodes housed in the container and provided with a negative electrode containing lithium titanate and a positive electrode.
With a non-aqueous electrolytic solution containing a solvent having a boiling point in the range of 85 ° C. or higher and 130 ° C. or lower, which is contained in the container.
Equipped with
Non-aqueous electrolyte batteries with ratios A / B and ratio B / C within the following range:
0.55 ≤ A / B ≤ 0.7: (1);
1.2 ≤ B / C ≤ 1.35: (2)
here,
^{A is the volume [cm 3} ] of the voids in the container excluding the voids of the electrode group.
B is the volume [cm ³ ] of the non-aqueous electrolyte solution.
C is the volume [cm ³ ] of the void in the electrode group.
[2] The non-aqueous electrolyte battery according to [1], wherein the volume ratio of the solvent to the non-aqueous electrolyte solution is in the range of 10% or more and 90% or less.
[3] The non-aqueous electrolyte battery according to [2], which has a volumetric energy density of 100 Wh / L or more.
[4] The non-aqueous electrolyte battery according to [2], wherein the boiling point of the solvent is in the range of 100 ° C. or higher and 120 ° C. or lower.
[5] The non-aqueous electrolyte battery according to [2], wherein the operating pressure of the gas release mechanism is 0.5 MPa or more and 1 MPa or less.

1 ... Exterior can, 2 ... Lid, 3 ... Positive electrode external terminal, 4 ... Negative electrode external terminal, 5 ... Electrode group, 6 ... Positive electrode, 6a ... Positive electrode current collecting tab, 6b ... Positive electrode active material-containing layer, 7 ... Negative electrode, 7a ... Negative electrode current collecting tab, 7b ... Negative electrode active material-containing layer, 8 ... Separator, 10 ... Positive electrode lead, 11 ... Negative electrode lead, 12 ... Liquid injection hole, 13 ... Safety valve, 13a ... Recession, 13b ... Groove, 14 ... Insulation gasket , 15 ... Internal insulator, 16 ... Insulation tape, 100 ... Non-aqueous electrolyte battery.

Claims (4)

A container with a gas release mechanism and
A group of electrodes housed in the container and provided with a negative electrode containing lithium titanate and a positive electrode.
A non-aqueous electrolytic solution containing a solvent having a boiling point in the range of 85 ° C. or higher and 130 ° C. or lower, which is contained in the container, is provided.
It has a volumetric energy density of 100 Wh / L or more,
Non-aqueous electrolyte batteries with ratios A / B and ratio B / C within the following range:
0.55 ≤ A / B ≤ 0.7: (1);
1.2 ≤ B / C ≤ 1.35: (2)
here,
^{A is the volume [cm 3} ] of the voids in the container excluding the voids of the electrode group.
B is the volume [cm ³ ] of the non-aqueous electrolyte solution.
C is the volume [cm ³ ] of the void in the electrode group. The non-aqueous electrolyte battery according to claim 1, wherein the volume ratio of the solvent to the non-aqueous electrolyte solution is in the range of 10% or more and 90% or less. The non-aqueous electrolyte battery according to claim 1 or 2 , wherein the boiling point of the solvent is in the range of 100 ° C. or higher and 120 ° C. or lower. The non-aqueous electrolyte battery according to any one of claims 1 to 3, wherein the operating pressure of the gas release mechanism is 0.5 MPa or more and 1 MPa or less.

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