JP7282482B2 - battery system - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to non-aqueous electrolyte batteries and battery systems.

Lead-acid batteries are used as the main batteries installed in automobiles. On the other hand, an idling stop vehicle is equipped with an assembled battery in which a non-aqueous electrolyte secondary battery using lithium titanate as a negative electrode active material and a lead-acid battery are connected in parallel in order to meet the demand and supply of large current. The average operating voltage of this assembled battery is about 2.4 V, and excellent life characteristics and output characteristics can be expected as compared with the case where a lead-acid battery is used as a main battery.

In order to further increase the current and extend the service life in the future, a vehicle power supply system that combines a lead-acid battery with a battery having a near full charge voltage is being studied.

Japanese Patent No. 3930574 Japanese Patent No. 5428708 U.S. Patent Publication US2010/255352A1 JP 2011-15516 A

The problem to be solved by the present invention is a non-aqueous electrolyte battery capable of reducing deterioration of lead-acid batteries connected in parallel and improving input/output performance at large currents, and a non-aqueous electrolyte battery comprising the battery. To provide a battery system.

According to embodiments, a battery system is provided. The battery system includes a first assembled battery composed of lead-acid batteries, and a second assembled battery connected in parallel to the first assembled battery and having a plurality of non-aqueous electrolyte batteries connected in series. A non-aqueous electrolyte battery includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. The negative electrode includes a negative electrode active material containing a lithium-titanium composite oxide having a spinel crystal structure with an average operating potential of 1.58 V (vs. Li/Li ⁺ ) or more. The lithium-titanium composite oxide contains at least one metal element selected from the group consisting of Mn, Co, Ni, V, Zr, Nb, Mo and W. The ratio of the atomic ratio of the metal element to the sum of the atomic ratio of the metal element and the atomic ratio of titanium is 0.5% or more .

1 is an exploded perspective view of a non-aqueous electrolyte battery according to an embodiment; FIG. 2 is a partially exploded perspective view of an electrode group used in the non-aqueous electrolyte battery of FIG. 1. FIG. 1 is a block diagram showing an electric circuit of a battery system according to an embodiment; FIG.

As listed in Patent Document 4, a lead-acid battery (first lead-acid battery) with an average operating voltage of 12 V and a non-aqueous electrolyte battery using lithium titanate with an average operating voltage of 12 V as a negative electrode (second non- A power supply system for idling stop vehicles has been developed that supplements the lead-acid battery at a relatively low cost by combining it with a water electrolyte battery and eliminating the need for a DC-DC converter.

However, in Patent Document 4, since the operating voltages of the first lead-acid battery and the second non-aqueous electrolyte battery are almost the same, the life of the lead-acid battery, which exhibits the most stable life when fully charged, does not improve much. Specifically, a lead-acid battery with an average operating voltage of 12V has a full charge final voltage of about 13.8V, a fully charged open circuit voltage of 13.2V, a fully discharged open circuit voltage of 10.8V, and a fully discharged voltage of 10.8V. is 9.0 V, and there is a range of voltages that actually operate. The second non-aqueous electrolyte battery using lithium titanate as the negative electrode has an average operating voltage of 2.4 V, a full charge end voltage of 2.8 V, a full charge open circuit voltage of 2.6 V, and a full discharge open circuit voltage of 2. .2V, and the full discharge voltage is about 1.8V. Therefore, when five second non-aqueous electrolyte batteries are connected in series, the average operating voltage is 12 V, the fully charged voltage is 14 V, and the fully discharged voltage is about 9 V, which are almost the same as those of the first lead-acid battery.

Therefore, when the second non-aqueous electrolyte battery using lithium titanate as the negative electrode discharges, the parallel-connected lead-acid battery cannot remain fully charged and is discharged to some extent. Therefore, although the battery system as a whole can achieve high input/output, deterioration of the lead-acid battery is not greatly suppressed.

If six second nonaqueous electrolyte batteries are connected in series, the average operating voltage can be 14.4V, the full charge voltage can be 16.8V, and the full discharge voltage can be 10.8V. In this case, the open circuit voltage at full discharge of the assembled battery in which six second non-aqueous electrolyte batteries are connected in series matches the open circuit voltage at full charge of the first lead-acid battery. Therefore, in the charging/discharging region of the assembled battery of the second non-aqueous electrolyte batteries, the first lead-acid battery can be fully charged, so that the first lead-acid battery is almost always maintained in a fully charged state. On the other hand, since the assembled battery of the second non-aqueous electrolyte battery is in a completely discharged state, the output is insufficient. In addition, it is possible to charge with a voltage exceeding the full charge voltage of the lead-acid battery, for example, about 14 V, but in that case, electrolysis of the electrolyte always progresses in the first lead-acid battery, and power loss continues to occur. , the problem of losing the fuel efficiency improvement effect remains. Furthermore, in the case of a vented lead-acid battery, maintenance is required because the frequency of water injection increases.
(First embodiment)
A first embodiment provides a non-aqueous electrolyte battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte. The negative electrode includes a negative electrode active material containing a lithium-titanium composite oxide having a spinel crystal structure with an average operating potential of 1.58 V (vs. Li/Li ⁺ ) or more. According to such a non-aqueous electrolyte battery, the battery voltage can be lowered by increasing the negative electrode potential while maintaining the positive electrode potential at a predetermined value.

When this negative electrode is used, for example, the non-aqueous electrolyte battery has an average operating voltage of 2.37V, a fully charged voltage of 2.77V, and a fully discharged voltage of 1.77V. When six of these batteries are connected in series, the resulting assembled battery has an average operating voltage of 14.22V, a full charge voltage of 16.62V, and a full discharge voltage of 10.62V. The following table shows the full charge end voltage, full charge open circuit voltage, average operating voltage, complete discharge open circuit voltage, and complete discharge end voltage of the non-aqueous electrolyte battery of the embodiment, the assembled battery of the non-aqueous electrolyte battery of the embodiment, and the lead-acid battery. 2.

A lead-acid battery (unit battery) has a voltage of about 2.0V. A 12V or 24V assembled battery in which a plurality of such cells are arranged in series is commercially available. A battery pack with a nominal voltage that slightly exceeds the upper limit voltage (for example, 12V) of a lead-acid battery pack can suppress a voltage drop due to discharge of the lead-acid battery when used in parallel with a lead-acid battery pack. The life of the entire assembled battery can be improved.

Lithium titanate (Li ₄ Ti ₅ O ₁₂ ) having a spinel crystal structure has an average operating potential of 1.55 V (vs. Li/Li ⁺ ), and a fully charged non-aqueous electrolyte battery using this as a negative electrode active material The voltage is about 2.8V. In an assembled battery in which five non-aqueous electrolyte batteries are connected in series, the operating voltage range of the lead-acid battery and the operating voltage range of the non-aqueous electrolyte battery match. Therefore, suppression of deterioration of the lead-acid battery cannot be expected.

On the other hand, by using a negative electrode active material containing a lithium-titanium composite oxide having a spinel-type crystal structure with an average operating potential of 1.58 V (vs. Li/Li ⁺ ) or more for the negative electrode, a non-aqueous electrolyte battery can be produced. The nominal voltage can be 2.37V or less. An assembled battery in which six non-aqueous electrolyte batteries having this nominal voltage are connected in series has an average operating voltage of about 14.22 V, so even if the non-aqueous electrolyte batteries have an SOC of about 50%, the lead-acid battery can be kept fully charged. , the deterioration of the lead-acid battery can be suppressed. The final operating voltage of the second non-aqueous electrolyte battery using lithium titanate (Li ₄ Ti ₅ O ₁₂ ) having a spinel crystal structure as the negative electrode active material is about 2.2 V. When 6 are connected in series, the final operating voltage of the assembled battery is 13.2V. In this case, the fully discharged open circuit voltage of the second non-aqueous electrolyte battery matches the fully charged open circuit voltage of the first lead-acid battery. Therefore, in the charging/discharging region of the second non-aqueous electrolyte battery, the first lead-acid battery can be fully charged. Since the non-aqueous electrolyte battery is in a completely discharged state, the output is insufficient. In addition, since the voltage exceeds the full charge voltage of the lead-acid battery, electrolysis of the electrolyte always progresses in the first lead-acid battery, and power loss continues, so the problem of losing the fuel efficiency improvement effect remains. Furthermore, in the case of a lead-acid battery with a release valve, maintenance is required because the frequency of water injection increases.

According to the first embodiment, the operating voltage of the non-aqueous electrolyte battery is lowered by increasing the negative electrode potential. Therefore, in the assembled battery in which six non-aqueous electrolyte batteries are connected in series according to the first embodiment, the voltage of the lead-acid battery is kept at full charge, thereby suppressing deterioration and improving the input/output characteristics of the non-aqueous electrolyte battery. can be improved. In a system in which this assembled battery is connected in parallel with an assembled battery of lead-acid batteries, the input/output of a large current is handled by the assembled battery of non-aqueous electrolyte batteries of the first embodiment, so voltage drop due to discharge of the lead-acid battery is suppressed. As a result, the life of the entire assembled battery is improved. For example, at least one metal element selected from the group consisting of Mn, Co, Ni, V, Zr, Nb, Mo and W in an amount equivalent to 10% in atomic ratio of titanium in Li ₄ Ti ₅ O ₁₂ By forming a solid solution with titanium, the average action potential can be lowered by about 0.15 V (vs. Li/Li ⁺ ) to about 1.65 V. This can result in an average operating voltage of the battery of about 2.30V. As a result, the SOC of the non-aqueous electrolyte battery at the open circuit voltage of 13.2 V when the lead-acid battery is fully charged is about 0% to about 25% in the case of an assembled battery in which six non-aqueous electrolyte batteries are connected in series. Therefore, the SOC (capacity) capable of inputting/outputting a large current is expanded while the lead-acid battery is kept fully charged, and the input/output performance at a large current is improved. Compared to five-series, the lead-acid battery is maintained at full charge over a wide SOC range of the non-aqueous electrolyte battery.

Here, the SOC indicates the state of charge of the non-aqueous electrolyte battery, with 100% being fully charged and 0% being completely discharged. Non-aqueous electrolyte batteries are charged at the current and voltage specified by the manufacturer. For example, a positive electrode containing manganese oxide and a negative electrode containing a negative electrode active material containing a lithium-titanium composite oxide having a spinel crystal structure of 1.55 (vs. Li/Li ⁺ ) of a non-aqueous electrolyte battery. In this case, after constant-current charging at 1C to the full charge voltage, constant-voltage charging at 2.8V is performed, and when the current value converges to 1/20C, constant-current and constant-voltage charging is performed. After resting for 10 minutes, the discharge capacity at the time of discharging to 1.8 V at 1 C is defined as the rated capacity. The SOC indicates the ratio of the charged amount of electricity to the rated capacity. Table 3 shows the non-aqueous electrolyte battery of another example of the embodiment, the assembled battery formed by connecting 6 such non-aqueous electrolyte batteries in series, the full charge end voltage of the lead storage battery, the full charge open circuit voltage, the average operating voltage, the full Discharge open circuit voltage, full discharge final voltage.

A nonaqueous electrolyte battery may include a container, an electrode group housed in the container and including a positive electrode, a negative electrode, and a separator, and a nonaqueous electrolyte housed in the container.

Any structure can be adopted for the electrode group as long as the positive electrode and the negative electrode face each other with a separator interposed therebetween. For example, the electrode group may have a structure in which a positive electrode and a negative electrode are laminated with a separator interposed therebetween, or a structure in which the positive electrode and the negative electrode are wound in a spiral shape or a flat spiral shape with a separator interposed therebetween. The shape of the electrode group as a whole can be determined according to the container in which it is housed.

The negative electrode, positive electrode, separator, nonaqueous electrolyte and container of the nonaqueous electrolyte battery are described below.

(1) Negative Electrode The negative electrode includes a negative electrode current collector and a negative electrode mixture layer formed on one or both sides of the negative electrode current collector.

The negative electrode mixture layer contains a negative electrode active material, and may optionally contain a negative electrode binder and a negative electrode electrical conductor.

The negative electrode active material includes a lithium-titanium composite oxide having a spinel crystal structure with an average operating potential of 1.58 V (vs. Li/Li ⁺ ) or more.

The upper limit of the average action potential is desirably 1.95 V (vs. Li/Li ⁺ ). This is because if the average operating potential is too high, the operating voltage of the battery may drop, resulting in a significant decrease in energy density. Also, the voltage range may become too low, and the SOC range of the non-aqueous electrolyte battery capable of keeping the lead-acid battery fully charged may be narrowed. A more preferable range of the average action potential is 1.60 V (vs. Li/Li ⁺ ) or more and 1.90 V (vs. Li/Li ⁺ ) or less. More preferably, it is 1.65 V (vs. Li/Li ⁺ ) or more and 1.85 V (vs. Li/Li ⁺ ) or less.

The average working potential is obtained by placing an electrode and a lithium metal foil facing each other, placing a separator therebetween, placing a lithium metal foil different from the lithium metal foil facing the electrode in the vicinity of the electrode, The battery is charged and discharged three times by moving lithium ions between the lithium metal foils facing the electrodes. The charge and discharge conditions are as follows: apply a reduction current to the measurement electrode from an OCV (open circuit voltage) of about 3 V, charge the electrode at 1 C to the full charge voltage, and then charge at a constant voltage of 1.0 V, and the current value is 1. A constant-current constant-voltage charge is applied to end charging when the temperature converges to /20C. Then, after resting for 10 minutes, discharge to 3V at 1C. A value obtained by dividing the discharge energy (Wh) at that time by the amount of discharge electricity is defined as the average operating voltage. The electrolytic solution is prepared by dissolving 1 mol/L of lithium hexafluorophosphate in a solvent containing ethylene carbonate and methyl ethyl carbonate at a volume ratio of 1:1. It is desirable to use the same separator as that used in the battery to be measured, but since the counter electrode is lithium metal, it is easily short-circuited, and if left as it is, the measurement may be hindered. Therefore, a glass filter non-woven fabric having a thickness of about 30 μm can be used as a separator.

Examples of the lithium-titanium composite oxide include those containing at least one metal element selected from the group consisting of Mn, Co, Ni, V, Zr, Nb, Mo and W. According to these, the average operating potential of the negative electrode can be increased (precious) while maintaining the spinel crystal structure of lithium titanate (Li ₄ Ti ₅ O ₁₂ ).

In the lithium-titanium composite oxide, it is desirable that the metal element forms a solid solution with titanium. Also, part of the titanium component may be substituted with a metal element.

The ratio of the atomic ratio of the metal element to the sum of the atomic ratio of titanium and the atomic ratio of the metal element is preferably 0.5% or more. A higher atomic ratio of the metal elements is advantageous in raising the average operating potential of the negative electrode, but too high a ratio causes an excessive drop in battery voltage. Therefore, a more preferable range is 1% or more and 59% or less, a further preferable range is 2% or more and 30% or less, and a still more preferable range is 5% or more and 10% or less.

A lithium-titanium composite oxide can be synthesized, for example, by the method described below. At least one metal element selected from the group consisting of lithium carbonate (Li ₂ CO ₃ ) powder, titanium dioxide (TiO ₂ ) powder, Mn, Co, Ni, V, Zr, Nb, Mo and W It is synthesized by dry mixing salt (eg nitrate) powders followed by heat treatment in air.

The heat treatment temperature is desirably in the range of 200° C. or higher and 850° C. or lower. This is because a phase having a structure different from the spinel type crystal structure is likely to be generated when the content is outside this range. A more preferable range of the heat treatment temperature is 250° C. or higher and 700° C. or lower, and a further preferable range is 400° C. or higher and 600° C. or lower.

The negative electrode binder is blended to fill gaps between the dispersed negative electrode active materials and to bind the negative electrode active material and the negative electrode current collector. Examples of negative electrode binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, and styrene-butadiene rubber.

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

The negative electrode active material, the negative electrode conductor, and the negative electrode binder in the negative electrode mixture layer are each in a proportion of 68% by mass to 96% by mass, 2% by mass to 16% by mass, and 2% by mass to 16% by mass. Blending is preferred. By setting the amount of the negative electrode conductive agent to 2% by mass or more, the current collection performance of the negative electrode layer can be further improved. Moreover, by setting the amount of the negative electrode binder to 2% by mass or more, the binding between the negative electrode active material-containing layer and the negative electrode current collector can be enhanced, and excellent cycle characteristics can be expected. On the other hand, it is preferable that the negative electrode conductive agent and the negative electrode binder each be 16% by mass or less in order to increase the capacity.

A material that is electrochemically stable at the lithium absorption and release potentials of lithium titanate can be used for the negative electrode current collector. The negative electrode current collector is preferably made of copper, nickel, stainless steel, aluminum, or an aluminum alloy containing one or more elements selected from Mg, Ti, Zn, Mn, Fe, Cu, and Si. The thickness of the negative electrode current collector is preferably in the range of 5 to 20 μm. A negative electrode current collector having such a thickness can balance the strength and weight reduction of the negative electrode.

For the negative electrode, for example, a slurry is prepared by suspending a negative electrode active material, a negative electrode binder and a negative electrode conductor in a solvent, and this slurry is applied to a current collector and dried to form a negative electrode mixture layer. It is produced by pressing. The negative electrode may also be produced by forming a negative electrode active material, a negative electrode binder, and a negative electrode conductive agent into pellets to form a negative electrode mixture layer, which is placed on a negative electrode current collector.
(2) Positive Electrode The positive electrode can include a positive electrode current collector and a positive electrode mixture layer formed on one side or both sides of the positive electrode current collector. The positive electrode mixture layer may include a positive electrode active material, a positive electrode binder, and a positive electrode conductor.

Examples of positive electrode active materials include various oxides and sulfides. For example, manganese dioxide (MnO ₂ ), iron oxide, copper oxide, nickel oxide, lithium manganese composite oxide (e.g. Li _x Mn ₂ O ₄ or Li _x MnO ₂ ), lithium nickel composite oxide (e.g. Li _x NiO ₂ ), lithium cobalt composite oxides (e.g. Li _x CoO ₂ ), lithium nickel cobalt composite oxides (e.g. Li _x Ni _1-yz Co _y M _z O ₂ (M is selected from the group consisting of Al, Cr and Fe at least one element, 0≦y≦0.5 and 0≦z≦0.1)), lithium manganese cobalt composite oxide (for example, Li _x Mn _1-y-z Co _y M _z O ₂ (M is at least one element selected from the group consisting of Al, Cr and Fe, and 0 ≤ y ≤ 0.5 and 0 ≤ z ≤ 0.1)), lithium manganese nickel composite compounds (for example Li _x Mn _1/2 Ni _1/2 O ₂ ), spinel-type lithium manganese nickel composite oxides (e.g. Li _x Mn _2-y Ni _y O ₄ ), lithium phosphorous oxides having an olivine structure (e.g. Li _x FePO ₄ , Li _x Fe _{1-y Mny} PO ₄ , Li _x CoPO ₄ etc.), iron sulfate (eg Fe ₂ (SO ₄ ) ₃ ), vanadium oxide (eg V ₂ O ₅ ), Li _x Ni _{1-a -b} Co _a Mn _{b Mc} O ₂ (0.9 < x ≤ 1.25, 0 < a ≤ 0.4, 0 ≤ b ≤ 0.45, 0 ≤ c ≤ 0.1, M is Mg, Al , represents at least one element selected from the group consisting of Si, Ti, Zn, Zr, Ca and Sn). In addition, organic materials and inorganic materials such as conductive polymer materials such as polyaniline and polypyrrole, disulfide polymer materials, sulfur (S), and carbon fluoride are also included. It should be noted that x, y, and z, which have no preferred ranges described above, are preferably in the range of 0 or more and 1 or less.

The positive electrode active material is represented by the composition formula Li _1-a Ni _x Co _y Mn _z O ₂ (−0.1≦a≦0.4, 0.1≦x/(y+z)≦1.3). Oxides are preferred. This is because, among positive electrode active materials such as lithium-manganese composite oxide and lithium-cobalt oxide, which are widely used at present, voltage adaptability is the highest when a six-series-connected assembled battery is formed.

Since x, y and z are each greater than 0 (0<x, 0<y, 0<z), this oxide is a nickel-cobalt-manganese composite oxide containing Ni, Co and Mn as essential components. . (1-a) becomes 0 when lithium is completely released by charging. The reason why the value of x/(y+z) is set within the above range is as follows. When the value of x/(y+z) is less than 0.1, the energy density of the positive electrode active material is lowered because the ratio of Ni to Co and Mn is decreased. On the other hand, when the value of x/(y+z) exceeds 1.3, the ratio of Ni to Co and Mn becomes large, so the thermal stability of the positive electrode active material is lowered. Therefore, the value of x/(y+z) should be 0.1 or more and 1.3 or less. A more preferable range is 0.6≦x/(y+z)≦1, y≧z. By setting y≧z, the thermal stability of the positive electrode active material is improved.

One type or two or more types of positive electrode active materials can be used.

The positive electrode binder is blended to bind the positive electrode active material and the positive electrode current collector. Examples of positive electrode binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluororubber.

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

In the positive electrode material mixture layer, it is preferable that the positive electrode active material and the positive electrode binder are mixed at a ratio of 80% by mass or more and 98% by mass or less and 2% by mass or more and 20% by mass or less. Sufficient electrode strength can be obtained by setting the amount of the positive electrode binder to 2% by mass or more. Also, by setting the positive electrode binder to 20% by mass or less, the content of the insulating material of the positive electrode can be reduced, and the internal resistance can be reduced.

When adding a conductive agent, the positive electrode active material, the positive electrode binder, and the positive electrode conductive agent are respectively 77% by mass or more and 95% by mass or less, 2% by mass or more and 20% by mass or less, and 3% by mass or more and 15% by mass or less. It is preferable to blend them in proportions. The above-mentioned effect can be sufficiently exhibited by setting the amount of the positive electrode conductive agent to 3% by mass or more. In addition, by making it 15% by mass or less, it is possible to reduce the decomposition of the non-aqueous electrolyte on the surface of the positive electrode conductor during storage at high temperatures.

The positive electrode current collector is preferably an aluminum foil or an aluminum alloy foil containing one or more elements selected from Mg, Ti, Zn, Ni, Cr, Mn, Fe, Cu and Si.

For the positive electrode, for example, a positive electrode active material, a positive electrode binder, and an optional positive electrode conductive agent are suspended in an appropriate solvent to prepare a slurry, and this slurry is applied to a positive electrode current collector and dried. After forming the positive electrode material mixture layer, it is produced by applying a press. The positive electrode is also produced by forming a positive electrode mixture layer by pelletizing a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent blended as necessary, and disposing this on a positive electrode current collector. may
(3) Separator The separator may be made of, for example, a porous film containing polyethylene, polypropylene, cellulose, or polyvinylidene fluoride (PVdF), or a synthetic resin nonwoven fabric. Among them, a porous film made of polyethylene or polypropylene melts at a certain temperature and can block electric current, so safety can be improved.
(4) Non-aqueous electrolyte The non-aqueous electrolyte is, for example, a liquid non-aqueous electrolyte prepared by dissolving an electrolyte in an organic solvent, or a gel non-aqueous electrolyte obtained by combining a liquid electrolyte and a polymer material. good.

The liquid non-aqueous electrolyte is preferably an electrolyte dissolved in an organic solvent at a concentration of 0.5 mol/L or more and 2.5 mol/L or less.

Examples of electrolytes dissolved in organic solvents include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium arsenic hexafluoride (LiAsF ₆ ), lithium trifluoromethosulfonate ( _LiCF3SO3 ), and _lithium bistrifluoromethylsulfonylimide [LiN( _{CF3SO2 ) 2} ], and mixtures thereof. The electrolyte is preferably one that is resistant to oxidation even at high potentials, most preferably LiPF ₆ .

Examples of organic solvents include cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), vinylene carbonate; linear carbonates such as diethyl carbonate (DEC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC); carbonates; cyclic ethers such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), dioxolane (DOX); chain ethers such as dimethoxyethane (DME) and diethoxyethane (DEE); γ-butyrolactone (GBL), Acetonitrile (AN) and sulfolane (SL) are included. These organic solvents can be used alone or as a mixed solvent.

Examples of polymeric materials include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO).

Alternatively, the non-aqueous electrolyte may be a room-temperature molten salt (ionic melt) containing lithium ions, a polymer solid electrolyte, an inorganic solid electrolyte, or the like.

Room-temperature molten salt (ionic melt) refers to a compound that can exist as a liquid at room temperature (within the range of 15 to 25° C.) among organic salts composed of a combination of organic cations and anions. The room-temperature molten salt includes a room-temperature molten salt that exists as a liquid by itself, a room-temperature molten salt that becomes liquid when mixed with an electrolyte, and a room-temperature molten salt that becomes liquid when dissolved in an organic solvent. In general, the melting point of room-temperature molten salt used in non-aqueous electrolyte batteries is 25° C. or lower. Also, organic cations generally have a quaternary ammonium skeleton.
(5) Container As the container, for example, a metal container having a thickness of 1 mm or less can be used. More preferably, the metal container has a thickness of 0.5 mm or less, more preferably 0.2 mm or less.

The shape of the container may be flat (thin), rectangular, cylindrical, coin-shaped, button-shaped, or the like. The container can take various forms depending on the battery dimensions.

Metal containers are made of aluminum, aluminum alloys, or the like. The aluminum alloy is preferably an alloy containing elements such as magnesium, zinc and silicon. When transition metals such as iron, copper, nickel, and chromium are included in the alloy, the content is preferably 1% by mass or less.

Alternatively, the container may be made of laminated film.

An example of the non-aqueous electrolyte battery of the first embodiment will be described with reference to FIGS. 1 and 2. FIG. As shown in FIG. 1, the nonaqueous electrolyte battery 20 includes a container 21a having an opening, a cover 21b welded to the opening of the container 21a, a flat electrode group 22 housed in the container 21a, and a non-aqueous electrolyte (not shown) housed in the container 21a and impregnated with the electrode group 22 .

The flat electrode group 22 includes a strip-shaped positive electrode 23 having a pair of long sides and a strip-shaped negative electrode 24 having a pair of long sides. As shown in FIG. 2, the positive electrode 23 and the negative electrode 24 are wound with a strip-shaped separator 25 having a pair of long sides sandwiched therebetween. The positive electrode 23, the negative electrode 24, and the separator 25 are wound with their long sides aligned.

The positive electrode 23 includes a positive electrode current collector 23a and a positive electrode mixture layer 23b carried on the surface of the positive electrode current collector 23a. As shown in FIG. 1, the positive electrode current collector 23a includes a strip-shaped portion 23c that extends in a direction parallel to the long side of the positive electrode current collector 23a and does not carry the positive electrode mixture layer 23b on its surface. This portion 23c can be used as a positive current collecting tab 23c.

As shown in FIG. 2, the negative electrode 24 includes a negative electrode current collector 24a and a negative electrode mixture layer 24b carried on the surface of the negative electrode current collector 24a. As shown in FIG. 1, the negative electrode current collector 24a includes a strip-shaped portion 24c that extends in a direction parallel to the long side of the negative electrode current collector 24a and does not carry the negative electrode mixture layer 24b on its surface. This portion 24c can be used as the negative electrode current collecting tab 24c. As shown in FIG. 1, the electrode group 22 has a spirally wound positive electrode current collecting tab 23c protruding from one end face, and a spirally wound negative electrode current collecting tab 24c protruding from the other end face. ing.

As shown in FIG. 1 , the flat electrode group 22 has two holding members 26 . The holding member 26 has a first holding portion 26a, a second holding portion 26b, and a connecting portion 26c that connects the first and second holding portions 26a and 26b. Since the positive electrode current collecting tab 23c and the negative electrode current collecting tab 24c are wound in a flat shape, the center of the winding is a space. Among these spaces, the connecting portion 26c of one holding member 26 is arranged in the space inside the positive electrode current collecting tab 23c, and the connecting portion 26c of the other holding member 26 is arranged in the space inside the negative electrode current collecting tab 24c. ing. With such an arrangement, the positive electrode current collecting tab 23c and the negative electrode current collecting tab 24c are partially sandwiched by the first sandwiching portion 26a with the connecting portion 26c as a boundary, and the positive electrode current collecting tab 23c or the positive electrode current collecting tab 23c or Another portion of the negative electrode current collecting tab 24c facing the above-described portion across the space is sandwiched by a second sandwiching portion 26b.

The outermost periphery of the electrode group 22 is covered with an insulating tape 27 except for the positive collector tab 23c and the negative collector tab 24c.

Lid 21b has a rectangular shape. The lid 21b has two through holes (not shown). A liquid injection port (not shown) for injecting a non-aqueous electrolyte is further opened in the lid 21b. The injection port is sealed with a sealing lid (not shown) after injection of the electrolytic solution.

The battery shown in FIG. 1 further includes a positive lead 28, a positive terminal 21c, a negative lead 29, and a negative terminal 21d.
The positive electrode lead 28 includes a connection plate 28a for electrically connecting to the positive electrode terminal 21c, a through hole 28b opened in the connection plate 28a, and a strip-shaped portion that is bifurcated from the connection plate 28a and extends downward. and a current collector 28c. The two collector portions 28c of the positive electrode lead 28 are electrically connected to the holding member 26 by welding with the sandwiching member 26 sandwiching the positive electrode current collecting tab 23c and the positive electrode current collecting tab 23c sandwiched therebetween.

The negative electrode lead 29 includes a connecting plate 29a for electrically connecting to the negative electrode terminal 21d, a through hole 29b opened in the connecting plate 29a, and a strip-shaped portion that is bifurcated from the connecting plate 29a and extends downward. and a current collector 29c. The two current collecting portions 29c of the negative electrode lead 29 are electrically connected to the negative electrode current collecting tab 24c by welding with the sandwiching member 26 sandwiching the negative electrode current collecting tab 24c therebetween and the negative electrode current collecting tab 24c. .

A method for electrically connecting the positive electrode lead 28 and the negative electrode lead 29 to the positive electrode current collecting tab 23c and the negative electrode current collecting tab 24c, respectively, is not particularly limited, but welding such as ultrasonic welding or laser welding may be used. mentioned.

A positive electrode terminal 21c and a positive electrode lead 28 are crimped and fixed to the lid 21b via an external insulating member 21e and an internal insulating member (not shown). With this arrangement, the positive terminal 21c and the positive lead 28 are electrically connected to each other and electrically insulated from the lid 21b. A negative electrode terminal 21d and a negative electrode lead 29 are crimped and fixed to the lid 21b via an external insulating member 21e and an internal insulating member (not shown). With this arrangement, the negative terminal 21d and the negative lead 29 are electrically connected to each other and electrically insulated from the lid 21b.

The non-aqueous electrolyte battery of the first embodiment described above includes a negative electrode containing a lithium-titanium composite oxide having a spinel-type crystal structure and an average operating potential of 1.58 V (vs. Li/Li ⁺ ) or more. As a result, the SOC (capacity) range in which high-current input/output is possible can be widened, so that the high-current input/output performance of the non-aqueous electrolyte battery can be improved. Moreover, deterioration of the lead-acid batteries connected in parallel can be reduced.
(Second embodiment)
A battery system according to a second embodiment includes a first assembled battery composed of a plurality of lead-acid batteries, and a second assembled battery connected in parallel to the first assembled battery and composed of a plurality of unit cells composed of non-aqueous electrolyte batteries connected in series. and the assembled battery. The non-aqueous electrolyte battery of the first embodiment can be used for the non-aqueous electrolyte battery.

A commercially available lead-acid battery can be used as the lead-acid battery. Commercially available lead-acid batteries have, for example, nominal voltages of 2V, 4V, 6V, 12V and 24V. For the electrical connection of the lead-acid batteries in the first assembled battery, series connection, parallel connection, or a combination of series connection and parallel connection can be used.

Next, an example of the battery system according to the embodiment will be described with reference to the drawings.

A battery system 1 shown in FIG. 3 includes a first assembled battery 10 and a second assembled battery 11 . The first assembled battery 10 is an assembled battery including a plurality of lead-acid batteries. These lead-acid batteries each have a nominal voltage of 2V and are connected in series. The second assembled battery 11 is connected in parallel to the first assembled battery 10 . The second assembled battery 11 includes a plurality of non-aqueous electrolyte batteries of the first embodiment. A plurality of non-aqueous electrolyte batteries are connected in series.

In the battery system 1 shown in FIG. 3 , a first assembled battery 10 and a second assembled battery 11 are connected in parallel via a circuit opening/closing means 30 .

The circuit opening/closing means 30 includes a semiconductor switch 31 . The semiconductor switch 31 includes a metal-oxide-semiconductor junction field effect transistor (MOF-FET) through which electrons can be switched on and off. Electric control means (ECU) 32 controls energization and cut-off of the electrons through the semiconductor switch 31 .

The voltage across the terminals of the first assembled battery 10 is monitored by a sensor (not shown), and the information is sent to the electronic control unit 32 .

Battery system 1 further comprises a first electrical load 40 and an alternator 50 . The first electric load 40 and the alternator 50 are connected in parallel to the first assembled battery 10 without the semiconductor switch 31 interposed therebetween. Also, the first electric load 40 and the alternator 50 are connected in parallel to the second assembled battery 11 via the semiconductor switch 31 .

The first electrical load 40 is an electrical load that is insensitive to changes in applied voltage.
Alternator 50 is an alternator that converts mechanical energy into electrical energy. Alternator 50 can send alternating current to a rectifier, not shown. This rectifier has the function of converting the received alternating current into a direct current and passing this direct current through the battery system 1 . A transmission voltage from the alternator 50 is monitored by a sensor (not shown), and the information is sent to the electronic control unit 32 .

Battery system 1 further comprises a second electrical load 60 . A second electrical load 60 is connected in parallel to the second assembled battery 11 without the semiconductor switch 31 interposed therebetween. A second electric load 60 is connected in parallel to the first assembled battery 10 , the first electric load 40 and the alternator 50 via the semiconductor switch 31 .

The second electrical load 60 is an electrical load that can malfunction when the applied voltage changes. The operating voltage of the second electric load 60 is set according to the nominal voltage of the first assembled battery 10 .

The battery system further comprises protection control means 70 for protecting the second assembled battery 11 . The protection control means 70 can include, for example, means (not shown) for monitoring the voltage across the terminals of the second assembled battery 11 . For example, when the voltage across the terminals of the second assembled battery 11 drops below the threshold value, the protection control means 70 sends a signal to the electronic control means 32 connected to the circuit opening/closing means 30 to cause the semiconductor switch 31 to switch to the first It is possible to prevent the second assembled battery 11 from being over-discharged by energizing the second assembled battery 11 from the first assembled battery 10 .

The application of the battery system 1 is not particularly limited, but may be, for example, an automotive battery system.

In the battery system 1, which is an automotive battery system, the first electrical load 40 includes, for example, air conditioning equipment and lighting equipment.

In a battery system 1, which is an automobile battery system, an alternator 50 is mechanically connected to an automobile engine. The alternator 50 is also connected to the braking system, and can convert the energy generated during braking of the vehicle into regenerative energy.

In the battery system 1, which is an automobile battery system, the second electric load 60 includes, for example, a car navigation device and audio equipment.

Next, power transmission in the battery system 1, which is an automotive battery system, will be described.

(1) When the engine is running While the engine of the automobile is running, the alternator 50 generates electricity, and the electricity thus generated is converted into direct current by a rectifier (not shown), and the first electric load 40 and the first assembled battery sent to 10.

During engine operation, when the transmitted voltage from the alternator 50 is within the range allowed by the second electrical load 60, the electronic control unit 32 places the solid-state switch 31 in a "energized" state, causing the electricity generated by the alternator 50 to is sent to the second assembled battery 11 and the second electrical load 60 .

A diode 33 is parasitic on the semiconductor switch 31 as a rectifying means that directs current from the first assembled battery 10 side to the second assembled battery 11 side in the forward direction. Therefore, even if the semiconductor switch 31 is in the "energized" state, power transmission from the second battery pack 11 to the first electric load 40 is suppressed by the parasitic diode 33 . Thanks to this, even if the second assembled battery 11 has a smaller capacity than the first assembled battery 10, it is possible to prevent the second assembled battery 11 from being over-discharged.

During engine operation, if the transmission voltage from the alternator 50 is outside the range allowed by the second electrical load 60, the electronic control unit 32 puts the solid-state switch 31 into the "shut off" state, causing the alternator 50 to The power transmission to the No. 2 assembled battery 11 and the second electric load 60 is interrupted. During this time, the second assembled battery 11 can send electricity to the second electrical load 60 .

(2) When the vehicle is braked When the vehicle is braked, the alternator 50 momentarily causes a larger current to flow through the battery system 1 than when the engine is operating. At this time, the electronic control unit 32 puts the semiconductor switch 31 into the "energized" state.

In the battery system 1, the second assembled battery 11 has a wide SOC (capacity) range capable of inputting and outputting a large current. Therefore, the large current generated by the alternator 50 during braking of the automobile flows more to the second assembled battery 11 than to the first assembled battery 10 . As a result, over-discharging and over-charging of the first assembled battery 10 are prevented, so deterioration of the first assembled battery 10 is suppressed and the life performance of the battery system 1 is improved.

(3) When the engine is stopped When the engine is stopped, the alternator 50 does not generate power, so power transmission from the alternator 50 is not performed. Instead, the first assembled battery 10 and the second assembled battery 11 are responsible for power transmission to the first electrical load 40 and the second electrical load 60 .

When the transmission voltage from the first assembled battery 10 is within the range allowed by the second electrical load 60, the electronic control unit 32 puts the semiconductor switch 31 in the "energized" state. The first assembled battery 10 thereby sends electricity to the first electrical load 40 and the second electrical load 60 . On the other hand, the second assembled battery 11 sends electricity exclusively to the second electrical load 60 due to the rectifying function of the parasitic diode 33 .

When the transmission voltage from the first assembled battery 10 is out of the range allowed by the second electrical load 60, the electronic control unit 32 puts the semiconductor switch 31 into the "shutdown" state. Therefore, the first assembled battery 10 sends electricity only to the first electrical load 40 . On the other hand, the second assembled battery 11 sends electricity only to the second electrical load 60 .

As described above, the operating voltage of the second electric load 60 is set according to the nominal voltage of the first assembled battery 10 . Therefore, actually, the time during which the power transmission voltage from the first assembled battery 10 is out of the range allowed by the second electric load 60 is extremely short. Therefore, power transmission to the second electric load 60 by only the second assembled battery 11 is also extremely short. Thanks to this, even when the second assembled battery 11 has a smaller capacity than the first assembled battery 10, it is possible to prevent the second assembled battery 11 from being over-discharged.

A battery system according to a second embodiment includes a second assembled battery in which a plurality of non-aqueous electrolyte batteries of the first embodiment are connected in series, and a second assembled battery connected in parallel to the second assembled battery and composed of a plurality of lead-acid batteries. 1 battery pack included. Since the second assembled battery can widen the SOC range (capacity range) in which high current input/output is possible, it is excellent in high current input/output performance. Therefore, when the battery system requires input/output with a large current, the second assembled battery is charged and discharged with a large current in preference to the first assembled battery. Overdischarge is prevented, and deterioration of the first assembled battery is suppressed. Thereby, the life performance of the battery system is improved.

[Example]
The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the examples listed below as long as the gist of the invention is not exceeded.

( Example 1)
<Preparation of positive electrode>
LiNi _0.333 Co _0.333 Mn _0.333 O ₂ particles were prepared as a positive electrode active material. A positive electrode active material, carbon black and PVdF were blended at weight ratios of 90%, 8% and 2%, and kneaded in N-methylpyrrolidone (NMP) to prepare a positive electrode slurry.

The prepared positive electrode slurry was applied to both sides of a strip-shaped aluminum foil having a pair of long sides. The coating amount was 60 g/m ² . At this time, the positive electrode slurry was not applied to the strip-shaped region extending in the direction parallel to one side of the aluminum foil. Then, it was dried and pressed to a density of 3.2 g/cc to form a positive electrode mixture layer, thereby obtaining a positive electrode. A strip-shaped region where the positive electrode slurry was not applied and the positive electrode material mixture layer was not carried was used as a positive electrode current collecting tab.

<Production of negative electrode>
Li ₂ CO ₃ , TiO ₂ and MnNO ₃ were powder-mixed so that the atomic ratio Li:Ti:Mn=4:4.75:0.25, and heated to 500° C. in air to form Li ₄ Ti _{4 . .75} Mn _0.25 O ₁₂ was obtained. A spinel structure was confirmed from an X-ray diffraction pattern.

The obtained negative electrode active material, carbon black, and PVdF were kneaded in NMP at weight ratios of 95%, 3%, and 2% to prepare negative electrode slurries.

The prepared negative electrode slurry was applied to both sides of a strip-shaped aluminum foil having a pair of long sides. The coating amount was 50 g/m ² . At this time, the negative electrode slurry was not applied to the strip-shaped region extending in the direction parallel to one side of the aluminum foil. Then, it was dried and pressed to a density of 2.0 g/cc to form a negative electrode mixture layer, thereby obtaining a negative electrode. A strip-shaped region where the negative electrode slurry was not applied and the negative electrode mixture layer was not carried was used as a negative electrode current collecting tab.

<Production of electrode group and single cell>
A strip-shaped polyethylene separator having a thickness of 30 μm was placed between the positive electrode and the negative electrode, and these were wound in a flat spiral shape to obtain an electrode group. The positive electrode lead was ultrasonically welded to the positive current collecting tab of the electrode group, and the negative electrode lead was ultrasonically welded to the negative electrode current collecting tab.

The non-aqueous electrolyte was prepared by dissolving LiPF ₆ as an electrolyte in a non-aqueous solvent in which polycarbonate and methyl ethyl carbonate were mixed.

After housing the electrode group in a container made of a laminate film containing aluminum, an electrolytic solution was injected. The container was heat-sealed with the ends of the positive electrode lead and the negative electrode lead projecting from the container to obtain a flat-type non-aqueous electrolyte battery.

The non-aqueous electrolyte battery was charged at a constant voltage to 2.7 V until the current converged to 0.2 A, then rested for 30 minutes, discharged at 10 A, and the capacity was measured. The battery capacity was 10 Ah.
<Production of assembled battery>
An assembled battery of non-aqueous electrolyte batteries was obtained as a second assembled battery by connecting six of the above-mentioned single cells in series. Furthermore, it was connected in parallel with a 6-series lead-acid battery (first assembled battery) having an average operating voltage of 12 V and a capacity of 50 Ah to form an assembled battery.
(Examples 2 to 66)
The composition of the negative electrode active material, the type of metal element, the ratio of the atomic ratio of the metal element to the total atomic ratio of Ti and the metal element (atomic ratio ratio), and the firing temperature are changed as shown in Tables 5 to 9. A flat type non-aqueous electrolyte battery was obtained in the same manner as described in Example 1. The battery capacity of the non-aqueous electrolyte battery (single cell) of each example was 10 Ah.

Otherwise, in the same manner as in Example 1, an assembled battery was obtained.
(Comparative example 1)
Li ₂ CO ₃ and TiO ₂ were powder-mixed in an atomic ratio of Li:Ti=4:5 and heated to 850° C. in air to obtain Li ₄ Ti ₅ O ₁₂ . A spinel structure was confirmed from an X-ray diffraction pattern. A negative electrode was produced in the same manner as in Example 1, except that the obtained negative electrode active material was used.

A positive electrode was produced in the same manner as in Example 1.

A flat-type non-aqueous electrolyte battery was obtained in the same manner as in Example 1, except that the obtained positive electrode and negative electrode were used. The battery capacity was 10 Ah. Otherwise, in the same manner as in Example 1, an assembled battery was obtained.
(Comparative example 2)
Li ₂ CO ₃ and TiO ₂ were powder-mixed in an atomic ratio of Li:Ti=4:5 and heated to 500° C. in air to obtain Li ₄ Ti ₅ O ₁₂ . A spinel structure was confirmed from an X-ray diffraction pattern. A negative electrode was produced in the same manner as in Example 1, except that the obtained negative electrode active material was used.

A positive electrode was produced in the same manner as in Example 1.

A flat-type non-aqueous electrolyte battery was obtained in the same manner as in Example 1, except that the obtained positive electrode and negative electrode were used. The battery capacity was 10 Ah. Otherwise, in the same manner as in Example 1, an assembled battery was obtained.
(Comparative Example 3)
An assembled battery was prepared by connecting 5 single cells prepared in the same manner as in Comparative Example 1 in series.

For the non-aqueous electrolyte batteries of Examples and Comparative Examples, after 100,000 cycles simulating a negative electrode operating potential {V (vs. Li/Li ⁺ )} and an engine start, acceleration, deceleration stop, the lead-acid battery was tested. The capacity retention rate was measured by the method shown below, and the results are shown in Tables 5 to 9.

(negative electrode working potential)
The negative electrode and the lithium metal foil are opposed to each other, a separator (a glass filter having a thickness of 30 μm) is placed between them, and a lithium metal foil different from the lithium metal foil facing the negative electrode is placed near the negative electrode, The battery is charged and discharged three times by moving lithium ions between the negative electrode and the lithium metal foil facing the negative electrode. The charge and discharge conditions are as follows: apply a reduction current to the measurement electrode from an OCV (open circuit voltage) of about 3 V, charge the electrode at 1 C to the full charge voltage, and then charge at a constant voltage of 1.0 V, and the current value is 1. When the temperature converges to /20C, the charging is terminated. After resting for 10 minutes, discharge to 3V at 1C. A value obtained by dividing the discharge energy (Wh) at that time by the amount of discharge electricity is defined as the average operating voltage. The electrolytic solution used was obtained by dissolving 1 mol/L of lithium hexafluorophosphate in a solvent containing ethylene carbonate and methyl ethyl carbonate at a volume ratio of 1:1.

(Method of measuring the capacity retention rate of a lead-acid battery after 100,000 cycles simulating engine start, acceleration, deceleration stop)
The assembled batteries of Examples 1 to 66 and Comparative Examples 1 to 3 were tested by repeating the following discharge 1, discharge 2, charge 1, and charge 2.

Discharge 1: Discharge at 600 A for 1 second to simulate engine start.

Discharge 2: Discharge at 300 A for 3 seconds to simulate acceleration.

Charging 1: In order to simulate charging during steady running, constant current charging at 10 A and then constant voltage charging at 13.8 V are performed for 120 seconds. In this case, 13.8V is aimed at the end-of-charge voltage of the lead-acid battery.

Charging 2: Charging is performed at 300 A for 3 seconds to simulate vehicle deceleration.

The capacity of the lead-acid battery was measured before and after 100,000 cycles. The measurement method was to measure the discharge capacity up to 9.0 V by 5 A constant current discharge after charging for 20 hours by 5 A constant current constant voltage charging at 13.8 V. Shown in Tables 5 to 9.

In the batteries of Examples 1 to 66 , as shown in Tables 5 to 9, the negative electrode working potential containing the lithium-titanium composite oxide having a spinel crystal structure increased (becomes noble) due to the addition of the metal element, and the lead-acid battery. Since the non-aqueous electrolyte battery can be charged and discharged from near full charge and power flows to the non-aqueous electrolyte battery, the lead-acid battery is hardly discharged, resulting in very little reduction in capacity of the lead-acid battery.
On the other hand, in the batteries of Comparative Examples 1 and 2, the non-aqueous electrolyte battery is completely discharged and cannot be discharged at 13.8 V, which is the full charge final voltage of the lead-acid battery. No, it is severely degraded.

In addition, since the battery of Comparative Example 3 can be charged and discharged in the same voltage range as the lead-acid battery, the shared current during discharge of the lead-acid battery is smaller than that of Comparative Examples 1 and 2. Although there is some improvement, the amount of decrease is greater than in Examples 1 to 66 because the discharge is still being performed.

By comparison of Examples 1 to 7, when the type of metal element is the same as Mn, for example, Example 1 in which the atomic ratio ratio (atomic ratio ratio) of Mn to the total atomic ratio of Ti and Mn is 2% or more and 30% or less. It can be seen that the capacity retention ratios of the lead-acid batteries of Examples 5-4 are higher than those of Examples 5-7. Even if the type of metal element is changed to Co, the same tendency is shown. In addition, when the types of metal elements are changed to Ni, V, Zr, Nb, Mo, and W, as is clear from the results in Tables 5 to 8, the atomic ratio of the metal elements to the total atomic ratio of Ti and the metal elements The capacity of the lead-acid battery after 100,000 cycles of the example in which the ratio (atomic ratio) is 5% or more and 10% or less tends to be larger than the example in which the atomic ratio is less than 5% or more than 10%. I understand. As is clear from the results in Tables 5 to 9, the negative electrode working potential can vary depending on the type and atomic ratio of the metal element. On the other hand, if the atomic ratio is too large, the crystal structure will be disturbed, the cycle characteristics will deteriorate, and the resistance will increase, causing a change in the capacity of the lead storage battery after 100000 cycles.

By comparison of Examples 58 to 63 , the capacity of the lead-acid battery after 100000 cycles of Examples 58 to 61 with a firing temperature of 250 ° C. or more and 700 ° C. or less is less than 250 ° C. or more than 700 ° C. Examples 62 to 700 ° C. It can be seen that it is larger than 63. If the sintering temperature is too high, the metal element will be arranged at sites other than the Ti sites in the crystal lattice, or a solid solution of Ti and the metal element will not be formed, resulting in an increase in resistance and a decrease in capacity. On the other hand, if the firing temperature is too low, the crystal structure is inappropriate, resulting in an increase in resistance and a decrease in capacity. This indirectly affects the capacity reduction of the lead-acid battery after cycling.

Further, by comparing Example 1 with Examples 64 to 66, Example 1, which includes a layered positive electrode active material containing 33.3 atomic % or more of Ni, shows that the capacity of the lead-acid battery after 100,000 cycles is Ni-based. Example 64 containing a positive electrode active material of , Example 65 containing a layered positive electrode active material mainly composed of Co , and Example 66 containing a positive electrode active material consisting of LiMn ₂ O ₄ .

According to the non-aqueous electrolyte battery of at least one of the embodiments and examples described above, a lithium-titanium composite oxide having a spinel-type crystal structure with an average operating potential of 1.58 V (vs. Li/Li ⁺ ) or more is used. Therefore, the deterioration of lead-acid batteries connected in parallel can be reduced. In addition, it is possible to improve the input/output performance at a large current by expanding the capacity (SOC) range in which the input/output at a large current is possible.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.
The invention described in the original claims of the present application is appended below.
[1]
a positive electrode;
a negative electrode comprising a negative electrode active material comprising a lithium-titanium composite oxide having a spinel-type crystal structure and having an average operating potential of 1.58 V (vs. Li/Li ⁺ ) or higher;
non-aqueous electrolyte and
A non-aqueous electrolyte battery containing
[2]
The non-aqueous electrolyte battery according to [1], wherein the lithium-titanium composite oxide contains at least one metal element selected from the group consisting of Mn, Co, Ni, V, Zr, Nb, Mo and W. .
[3]
[2], wherein the metal element forms a solid solution with titanium, and the ratio of the atomic ratio of the metal element to the sum of the atomic ratio of the metal element and the atomic ratio of titanium is 0.5% or more. Non-aqueous electrolyte battery.
[4]
The non-aqueous electrolyte battery according to [2], which is used in a system including a lead-acid battery.
[5]
a first assembled battery comprising a lead-acid battery;
A second assembled battery in which a plurality of non-aqueous electrolyte batteries according to any one of [1] to [3] are connected in parallel to the first assembled battery and connected in series
including a battery system.

DESCRIPTION OF SYMBOLS 1... Battery system 10... First assembled battery 11... Second assembled battery 21a... Container 21b... Lid 21c... Positive electrode terminal 21d... Negative electrode terminal 22... Electrode group 23... Positive electrode 23b... Positive electrode mixture layer 23c... Positive electrode current collecting tab 24... Negative electrode 24b... Negative electrode mixture layer 24c... Negative electrode current collecting tab 25... Separator 26... Sandwiching member 28... Positive electrode lead 29... Negative electrode lead 30 Circuit opening/closing means 31 Semiconductor switch 32 Electric control means (ECU) 40 First electric load 50 Alternator 60 Second electric load.

Claims (4)

a first assembled battery comprising a lead-acid battery;
A second assembled battery connected in parallel to the first assembled battery and having a plurality of non-aqueous electrolyte batteries connected in series,
The non-aqueous electrolyte battery is
a positive electrode;
a negative electrode comprising a negative electrode active material comprising a lithium-titanium composite oxide having a spinel-type crystal structure and having an average operating potential of 1.58 V (vs. Li/Li ⁺ ) or higher;
and a non-aqueous electrolyte,
The lithium-titanium composite oxide contains at least one metal element selected from the group consisting of Mn, Co, Ni, V, Zr, Nb, Mo and W,
The ratio of the atomic ratio of the metal element to the sum of the atomic ratio of the metal element and the atomic ratio of titanium is 0.5% or more.
battery system. The battery system according to claim 1, wherein said first assembled battery has a voltage of 12V or 24V. 3. The battery system according to claim 1, wherein said second assembled battery includes an assembled battery in which six said non-aqueous electrolyte batteries are connected in series. The battery system according to any one of claims 1 to 3, wherein said average operating potential of said lithium-titanium composite oxide is 1.95 V (vs. Li/Li ⁺ ) or less.

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