JP5118905B2 - Electrode active material, electrode, non-aqueous electrolyte secondary battery, vehicle, battery-mounted device, and method for producing electrode active material - Google Patents

Description

  The present invention relates to an electrode active material, an electrode including the electrode active material, a non-aqueous electrolyte secondary battery including the electrode, a vehicle equipped with the non-aqueous electrolyte secondary battery, a battery-mounted device, and a method for manufacturing the electrode active material About.

From the viewpoints of high functionality, large capacity, low cost, etc. of the nonaqueous electrolyte secondary battery, various materials have been studied for the electrode active material. For example, a positive electrode active material mainly composed of an olivine-type lithium-containing iron phosphate complex represented by LiFePO ₄ has been proposed (see Patent Document 1). Moreover, the general _{formula: (Li 2 O) a ·} (Fe 2 O 3) b · (V 2 O 5) c · (P 2 O 5) d ( where, 0 ≦ a ≦ 0.5,0 ≦ b ≦ An electrode active material mainly composed of lithium-containing iron vanadium phosphate glass and glass ceramics represented by 0.5, 0 ≦ c ≦ 0.5, 0 ≦ d ≦ 0.5 is known (Patent Document 2). reference).

JP 09-134724 A JP 2007-42618 A

  Since the lithium-containing iron phosphate complex proposed in Patent Document 1 has low conductivity, when this is used as a positive electrode active material for a nonaqueous electrolyte secondary battery, the discharge rate characteristics and low-temperature characteristics of the battery are sufficient. There is a problem that is not. Therefore, Patent Document 2 proposes that an electrode active material mainly composed of lithium-containing iron vanadium phosphate glass and glass ceramic is used for the positive electrode of the nonaqueous electrolyte secondary battery. Thereby, the discharge rate characteristic of this battery can be made higher than that of the lithium-containing iron phosphate complex of Patent Document 1. The discharge rate characteristic refers to the magnitude of the change in battery voltage that occurs when the battery continues to be discharged at a predetermined current. The high discharge rate characteristic refers to the battery voltage even when discharged with a large discharge current. Is relatively less likely to decrease, and indicates a transition at a high value.

However, even in a battery using the electrode active material according to Patent Document 2, when the discharge current is increased, the battery voltage rapidly decreases. That is, the discharge rate characteristic is not sufficient. As a specific example, FIG. 2 shows an electrode active material (general formula: (Li ₂ O) _0.5 · (Fe ₂ O ₃ ) _0.5 · (V ₂ O ₅ ) _0.5 · (P ₂ O ₅ ) _{0.5 according to} Patent Document 2. ) Is used for the positive electrode of a non-aqueous electrolyte secondary battery, and a graph showing the discharge rate characteristics is shown (detailed experimental conditions will be described later). In this graph, the horizontal axis represents the discharge capacity per unit weight of the positive electrode active material, and the vertical axis represents the battery voltage.

In this battery, when the discharge current per unit area of the positive electrode (hereinafter also referred to as unit area discharge current) is discharged with a relatively small current of 0.1 or 0.2 mA / cm ² , the battery voltage gradually increases. The state of decrease and the state of decrease are almost the same (for example, when the discharge capacity per unit weight is 100 mAh / g, the battery voltage is 2.6 V in all cases). On the other hand, when discharging at a discharge current larger than these, for example, a current corresponding to a unit area discharge current of 0.5 mA / cm ² or more, the battery voltage is 0.1 or 0.2 mA / cm ^2. It drops faster than the battery voltage of, and then remains at a low value.

Moreover, it can be seen that as the unit area discharge current increases to 0.5, 1.0, and 2.0 mA / cm ² , the battery voltage decreases faster and then remains at a low value ( For example, battery voltages when the discharge capacity per unit weight of the electrode active material is 100 mAh / g are 2.1, 1.8, and 1.5 V, respectively). In other words, even with a battery using this electrode active material, if the discharge is performed with a relatively large unit area discharge current of 0.5 mA / cm ² or more, the lower limit voltage of the battery is reached in a short time. You can't make it too big. Therefore, for example, even when this battery is mounted on a hybrid electric vehicle and sudden start or acceleration is desired, this battery cannot sufficiently supply the required large discharge current. Alternatively, control that does not allow a large discharge current to flow is unavoidable.

  The present invention has been made in view of the present situation, and when used in a non-aqueous electrolyte secondary battery, when a particularly large discharge current (unit area discharge current) is passed, the lithium-containing iron vanadium phosphate is used. An object of the present invention is to provide an electrode active material in which the discharge rate characteristics of the battery are higher than when an electrode active material is used. Furthermore, an electrode using this electrode active material, a non-aqueous electrolyte secondary battery having high discharge rate characteristics using this electrode, and capable of obtaining a large discharge current (unit area discharge current) and power (battery output) An object of the present invention is to provide a vehicle on which the nonaqueous electrolyte secondary battery is mounted, a battery-mounted device, and a method for manufacturing an electrode active material.

The solution is an electrode active material used for an electrode of a non-aqueous electrolyte secondary battery, which has a general formula: (Li ₂ O) _a · (Fe ₂ O ₃ ) _b · (M ₂ O ₃ ) _{0.5- b} · (V ₂ O ₅ ) _c · (P ₂ O ₅ ) _d (M: at least one of Co, Mn, and Ni) provided that 0 <a ≦ 0.5, 0 <b <0.5, 0 <c It is an electrode active material mainly composed of at least one of glass and glass ceramics made of lithium-containing iron vanadium phosphate represented by ≦ 0.5 and 0 <d ≦ 0.5.
Furthermore, another solution is an electrode active material used for an electrode of a non-aqueous electrolyte secondary battery, which has a general formula: (Li ₂ O) _a · (Fe ₂ O ₃ ) _b · (Co ₂ O ₃ ) _{0.5 -b.} (V ₂ O ₅ ) _c · (P ₂ O ₅ ) _d provided that 0 <a ≦ 0.5, 0 <b <0.5, 0 <c ≦ 0.5, 0 <d ≦ 0. 5 is an electrode active material mainly composed of at least one of glass and glass ceramics made of lithium-containing iron cobalt vanadium phosphate represented by 5.

These electrode active materials of the present invention include lithium-containing iron vanadium phosphate or lithium-containing iron cobalt vanadium phosphate containing both Fe and metal M (M: at least one of Co, Mn, and Ni) or Co. The main component is at least one of glass and glass ceramics.
When this electrode active material is used for an electrode (positive electrode) of a nonaqueous electrolyte secondary battery, the electrode active material of Patent Document 2, that is, an electrode active material containing Fe but not containing metal M including Co is used. A battery having a higher discharge rate characteristic than when used can be configured. In particular, when the discharge current is large (unit area discharge current is 0.5 mA / cm ² or more), it is possible to suppress a decrease in battery voltage due to discharge. Thus, when the electrode active material of the present invention is used for an electrode of a nonaqueous electrolyte secondary battery, a large discharge current can flow and a large power (battery output) can be obtained.

On the other hand, in the olivine-type lithium-containing iron phosphate complex LiFePO ₄ proposed in Patent Document 1, even if this constituent element Fe is Co, the discharge of the non-aqueous electrolyte secondary battery using this as an electrode is used. Rate characteristics cannot be improved (Reference: Journal of Power Sources 160 (2006) 523-528). However, vanadium is added to this LiFePO ₄ , and further, as in the present invention, a part of Fe is replaced with metal M or Co among them, and the metal M or Co among them is contained together with Fe. When it does, in the battery using it, a discharge rate characteristic can be improved as mentioned above. Therefore, in lithium-containing iron vanadium phosphoric acid, a new finding has been obtained that when a part of Fe is contained together with the metal M or Co among them, the discharge rate characteristics of a battery using the Fe are improved.

  The symbols a, b, c, and d used in the general formula of the electrode active material are 0 <a ≦ 0.5, 0 <b <0.5, 0 <c ≦ 0.5, 0. <D ≦ 0.5 may be satisfied, but preferably a = c = d = 0.5 and 0.2 ≦ b ≦ 0.3. By using an electrode active material having such a composition for a non-aqueous electrolyte secondary battery, a battery having high discharge rate characteristics can be reliably configured.

  Further, in this electrode active material, as the cations to be inserted / leaved, alkali metal ions such as lithium ion, sodium ion, potassium ion and cesium ion, alkaline earth metals such as calcium ion and barium ion, magnesium ion, Ammonium ions such as aluminum ion, silver ion, zinc ion, tetrabutylammonium ion, tetraethylammonium ion, tetramethylammonium ion and triethylammonium ion, imidazolium ions such as imidazolium ion and ethylmethylimidazolium ion, pyridinium ion , Hydrogen ion, tetraethylphosphonium ion, tetramethylphosphonium ion, tetraphenylphosphonium ion, tetraphenylsulfonium ion Triethyl phosphonium ion, and the like. Of these, alkali metal ions are preferably used, and lithium ions are more preferably used.

  The electrode active material of the present invention can be used as a positive electrode active material or a negative electrode active material depending on selection of other battery constituent materials, particularly the electrode active material constituting the other electrode. However, from the potential, the electrode active material of the present invention is preferably used as a positive electrode active material. When the electrode active material of the present invention is used as a positive electrode active material, as a negative electrode active material that is the counter electrode, metals such as Li, Na, Mg, Ca, Al, alloys thereof, or cations are inserted / extracted. Possible carbon materials can be used.

  Furthermore, the electrode active material described above may be an electrode active material satisfying a = c = d = 0.5 and 0.2 ≦ b ≦ 0.3.

When the electrode active material of the present invention satisfying a = c = d = 0.5 and 0.2 ≦ b ≦ 0.3 is used for the electrode of the nonaqueous electrolyte secondary battery, the electrode described in Patent Document 2 Compared with the case where an active material is used, a battery having high discharge rate characteristics can be configured. In particular, when the discharge current is large (unit area discharge current is 0.5 mA / cm ² or more), it is possible to reliably suppress a decrease in battery voltage due to discharge. Thus, when the electrode active material of the present invention is used for an electrode of a non-aqueous electrolyte secondary battery, a large discharge current can surely flow.

  Furthermore, another solution is an electrode comprising the above-described electrode active material.

The electrode of the present invention includes the above-described electrode active material. Therefore, when this electrode is used as an electrode of a nonaqueous electrolyte secondary battery, it can be a battery having high discharge rate characteristics. In particular, when the discharge current of this battery is large (the unit area discharge current is 0.5 mA / cm ² or more), it is possible to suppress a decrease in battery voltage due to discharge.

  In addition, as an electrode, this electrode active material is compression-molded, and the electrode of the pellet shape of various shapes, such as a disk shape and a square plate shape, is mentioned, for example. Moreover, the electrode plate (or electrode foil) which carries | supports the electrode active material of this invention extensively on the main surface of the electrical power collector (or current collector foil) which consists of electroconductive materials, such as a metal, is also mentioned.

  Furthermore, another solution is a nonaqueous electrolyte secondary battery including the above-described electrode.

The nonaqueous electrolyte secondary battery of the present invention includes the above-described electrode. For this reason, it can be set as the battery which has a high discharge rate characteristic. In particular, when the discharge current of this battery is large (the unit area discharge current is 0.5 mA / cm ² or more), it is possible to suppress a decrease in battery voltage due to discharge. Therefore, it can be set as the nonaqueous electrolyte secondary battery which can supply a big discharge current and electric power (battery output).

  Furthermore, another solution is a vehicle on which the above-described non-aqueous electrolyte secondary battery is mounted.

In the vehicle of the present invention, the above-described non-aqueous electrolyte secondary battery is mounted. This non-aqueous electrolyte secondary battery can supply a large discharge current and electric power (battery output) corresponding to a unit area discharge current of 0.5 mA / cm ² or more to a motor for driving the wheel. For this reason, it can be set as the vehicle which has the driving performance which can perform sudden start and rapid acceleration smoothly.

Further, in the above-described vehicle, the non-aqueous electrolyte secondary battery is configured to allow discharge with a discharge current having a magnitude such that a discharge current per unit area of the electrode is 0.5 mA / cm ² or more. The vehicle is preferably equipped with a device.

In the vehicle of the present invention, in addition to the non-aqueous electrolyte secondary battery described above, a discharge control device that allows discharge at a discharge current corresponding to a unit area discharge current of 0.5 mA / cm ² or more is mounted. In this vehicle, the wheel is driven by a relatively large discharge current and electric power (battery output) corresponding to a unit area discharge current of 0.5 mA / cm ² or more from the nonaqueous electrolyte secondary battery according to the control of the discharge control device. Can be supplied to the motor. For this reason, it can be set as the vehicle which has the driving performance which can perform sudden start and rapid acceleration smoothly.

  Note that a vehicle equipped with a battery may be any vehicle that uses electric energy from a battery for all or a part of its power source. For example, an electric vehicle, a hybrid electric vehicle, a forklift, an electric wheelchair, an electric assist Bicycles, electric scooters, and railway vehicles are examples. Further, by using the above-described battery, the controllable discharge current range in the charge / discharge control device can be expanded to the large current side. Therefore, particularly when applied to a vehicle using electric energy of a battery as a part of a power source, for example, a hybrid electric vehicle, the ratio of driving the wheel by the driving motor to the driving of the wheel by the engine is increased. There is an advantage that the vehicle can be improved in fuel efficiency.

  Furthermore, another solution is a battery-equipped device on which the nonaqueous electrolyte secondary battery is mounted.

  The battery-equipped device of the present invention is equipped with the above-described non-aqueous electrolyte secondary battery. Therefore, this battery can be a battery-equipped device that can be used even in a usage method that temporarily requires a large discharge current and electric power (battery output).

  The battery-mounted device may be any device that uses the mounted battery as at least one of the energy sources. For example, various home appliances driven by a battery such as a personal computer, a mobile phone, and a battery-driven electric tool. Products, office equipment and industrial equipment. However, it is more preferable to apply to electric tools and industrial equipment that temporarily require a large discharge current and electric power (battery output).

Furthermore, another solution is an electrode active material used for an electrode of a non-aqueous electrolyte secondary battery, which has a general formula: (Li ₂ O) _a · (Fe ₂ O ₃ ) _b · (M ₂ O ₃ ) _{0.5 -b} · (V ₂ O ₅ ) _c · (P ₂ O ₅ ) _d (M: at least one of Co, Mn, and Ni) where 0 <a ≦ 0.5, 0 <b <0.5, 0 < A method for producing an electrode active material mainly comprising at least one of glass and glass ceramics comprising lithium-containing iron vanadium phosphate represented by c ≦ 0.5, 0 <d ≦ 0.5, wherein Li, Fe , A melting step of heating and melting a mixture in which compounds containing five elements of M, V, and P are mixed at a predetermined molar ratio, a solidifying step of rapidly cooling and solidifying the mixture, and a glass transition temperature thereof. An annealing treatment step of heating and holding at a temperature not lower than the melting point and not higher than the melting point, It is a production method.
Furthermore, another solution is an electrode active material used for an electrode of a non-aqueous electrolyte secondary battery, which has a general formula: (Li ₂ O) _a · (Fe ₂ O ₃ ) _b · (Co ₂ O ₃ ) _{0.5 -b.} (V ₂ O ₅ ) _c · (P ₂ O ₅ ) _d provided that 0 <a ≦ 0.5, 0 <b <0.5, 0 <c ≦ 0.5, 0 <d ≦ 0. A method for producing an electrode active material mainly composed of at least one of glass and glass ceramics made of lithium-containing iron cobalt vanadium phosphate represented by 5, comprising five elements of Li, Fe, Co, V, and P A melting step for heating and melting a mixture in which compounds are mixed at a predetermined molar ratio, a solidification step for rapidly cooling and solidifying the mixture, and an annealing for heating and holding the mixture at a temperature not lower than the glass transition temperature and not higher than the melting point. A process for producing the electrode active material.

  These electrode active material manufacturing methods of the present invention include a melting step, a solidification step, and an annealing treatment step. Therefore, the main component is at least one of glass and glass ceramics made of lithium-containing iron vanadium phosphate or lithium-containing iron cobalt vanadium phosphate containing Li, V, and P in addition to Fe and metal M or Co. The electrode active material can be manufactured.

In the melting step, examples of the compound that can be a supply source of Li, Fe, metal M, or five elements of Co, V, and P thereof include oxides composed of these elements and oxygen.
Moreover, as the heating temperature in the annealing treatment step, a temperature between the glass transition temperature and the melting point of the electrode active material to be treated is preferably selected.

  Furthermore, another solution is the above-described method for producing an electrode active material, wherein the annealing treatment step is preferably a method for producing an electrode active material which is a step of heating and holding at a temperature not lower than the crystallization temperature and not higher than the melting point. .

  In the method for producing an electrode active material of the present invention, in the annealing treatment step, the electrode active material is heated and held at a temperature not lower than the crystallization temperature and not higher than the melting point. Thereby, an electrode active material having better potential conductivity can be produced.

As the heating temperature in the annealing treatment step, for example, the above-described LiFe _0.5 Co _0.5 VPO ₇ ((Li ₂ O) _0.5. (Fe ₂ O ₃ ) _0.25. (Co ₂ O ₃ ) _0.25. (V ₂ O ₅ ) _0.5 The crystallization temperature of (P ₂ O ₅ ) _0.5 ) is 465 ° C., which is higher than the glass transition temperature, and the melting point is 600 ° C. Therefore, the heating temperature is preferably within that range, for example 500 It should be ℃.

(Embodiment 1)
First, Embodiment 1 of the present invention will be described with reference to the drawings.
FIG. 1 shows a lithium ion secondary battery 100 (hereinafter also simply referred to as a battery 100) according to Embodiment 1, FIG. 1 (a) is a perspective view of the battery 100, and FIG. 1 (b) is an enlarged longitudinal section. FIG.
This battery 100 is a nonaqueous electrolyte secondary battery including a battery case 50, a negative electrode 20, a separator 30, and an electrolyte solution (not shown), in addition to the positive electrode 10 mainly formed by compression molding of the positive electrode active material 1.

Among these, the battery case 50 is made of a stainless steel plate, and has a substantially coin shape having a circular bottom portion 51a and a thickness in the height direction DH. Specifically, the coin type battery case has a thickness (height) in the height direction DH of 2 mm and a circular diameter of 32 mm (2032 type). The battery case 50 includes a container body 51 and a lid body 52. Among these, the container body 51 includes a disk-shaped bottom portion 51a and a cylindrical wall portion 51b that rises from the peripheral edge in a direction perpendicular to the peripheral edge and is bent inward at the tip side and reduced in diameter. The lid 52 has a disk shape and is formed by sealing an opening 51c formed by the tip of the cylindrical wall 51b. An insulating gasket 53 is interposed between the container body 51 and the lid body 52, and serves also as a positive electrode terminal and a negative electrode terminal, respectively.
Inside the battery case 50, a pair of a positive electrode 10 and a negative electrode 20 are stacked in the height direction DH via a separator 30 (see FIG. 2B). The positive electrode 10 is disposed on the bottom 51a side of the container body 51, and the negative electrode 20 is disposed on the lid body 52 side to be electrically connected. Further, the gasket 53 described above is configured so that the negative electrode 20 is prevented from touching the cylindrical wall portion 51b of the container body 51 serving as the positive electrode terminal, and all of the inner surface 51bx of the cylindrical wall portion 51b and the inner surface 51ax of the bottom plate 51a. A part of is covered.

Next, the positive electrode 10 according to the first embodiment will be described. This positive electrode 10 is obtained by compression molding a mixture of a positive electrode active material 1, a conductive material 5 made of acetylene black (AB), and a binder 6 made of polytetrafluoroethylene (PTFE). Specifically, the positive electrode active material 1, the conductive material 5, and the binder 6 were mixed by 0.250 g, 0.089 g, and 0.018 g, respectively (mass ratio 70: 25: 5), and the diameter was 10 mm. It is compression-molded into a disk-shaped pellet having a thickness of 0.5 mm.
On the other hand, a circular lithium foil having a diameter of 15 mm and a thickness of 0.15 mm was used as the negative electrode 20. As the separator 30, a porous polyethylene sheet having a diameter of 20 mm and a thickness of 0.02 mm was used. Further, as the electrolytic solution, a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / l in a mixed solvent of ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1 was used. This electrolytic solution is absorbed and supported inside the separator 30 described above.

Next, the positive electrode active material 1 according to Embodiment 1 will be described.
This positive electrode active material 1 is made of (Li ₂ O) _{0.5 .multidot.} (Fe ₂ O ₃ ) _{0.25.multidot.} (Co ₂ O ₃ ) _{0.25.multidot.} (V ₂ O ₅ ) _0.5. (P ₂ O ₅ ) A glass body represented by _0.5 . The crystallization temperature and melting point of this positive electrode active material are 465 ° C. and 600 ° C. In addition, about these temperature, it calculated | required by DTA (Differential Thermal Analysis: Differential thermal analysis).

  Furthermore, the discharge rate characteristic of this battery when the positive electrode active material 1 according to Embodiment 1 was used for the positive electrode of a lithium ion secondary battery was investigated.

As a comparative example of the positive electrode active material 1 described above, the positive electrode active material 2 ((Li ₂ O) _{0.5 .multidot.} (Fe ₂ O ₃ ) _{0.5 .multidot.} (V ₂ O ₅ ) _{0.5 .multidot.} (P ₂ O ₅ ) _0.5 ) was prepared.
Using these positive electrode active materials 1 and 2, batteries C1 and C2 having the same specifications as those of the above-described lithium ion secondary battery 100 were prepared except for the positive electrode active material. And the discharge rate characteristic was evaluated about these batteries C1 and C2. Specifically, in a temperature environment of 25 ° C., the battery C1 and C2 are charged until the battery voltage reaches 5 V at a charging current corresponding to a positive electrode unit area of 0.1 mA / cm ^2. Current charging and constant current discharge with unit area discharge current of any one of 0.1, 0.2, 0.5, 1.0, and 2.0 mA / cm ² (battery voltage for terminating discharge is 1V) was repeated. Moreover, the discharge was performed in ascending order of unit area discharge current. That is, after charging, first, constant current discharge is performed at a unit area discharge current of 0.1 mA / cm ² , and then charging is performed again. Then, constant current discharge is performed at a unit area discharge current of 0.2 mA / cm ^2. The charge and discharge were performed up to a constant current discharge of 2.0 mA / cm ² . The test results are shown in FIG. 2 and FIG.

FIG. 2 is a graph showing the discharge rate characteristics in the battery C2 using the conventional positive electrode active material 2 that does not contain cobalt. In addition, the horizontal axis of this graph shows the discharge capacity per unit weight of the positive electrode active material 2, and the vertical axis shows the battery voltage of the battery C2.
In the battery C2, as described above, when discharged with a unit area discharge current of 0.5 mA / cm ² or more, discharge is performed as compared with the case of discharging with a unit area discharge current of 0.1 or 0.2 mA / cm ^2. Despite the small capacity, the battery voltage quickly dropped and remained low. Moreover, it can be seen that when the value of the unit area discharge current is increased, the battery voltage due to the discharge is greatly reduced at an earlier stage and thereafter remains low.

On the other hand, FIG. 3 is a graph showing discharge rate characteristics in the battery C1 using the positive electrode active material 1. In this graph, the horizontal axis represents the discharge capacity per unit weight of the positive electrode active material 1, and the vertical axis represents the battery voltage of the battery C1.
In the battery C1, regardless of which unit area discharge current is used for discharge, the battery voltage gradually decreases almost linearly after the battery voltage drops to around 3 V at the beginning of discharge. In this battery C1, as in the case of the above-described battery C2, the battery voltage greatly decreases as the unit area discharge current value increases. However, as is clear from the case of discharging with a relatively large unit area discharge current of 0.5 mA / cm ² or more as compared with the case of the battery C2, it can be seen that the decrease in the battery voltage due to the discharge is small. Table 1 shows the battery voltage at each unit area discharge current when the discharge capacity per unit weight of the positive electrode active material was 100 mAh / g for the above-described battery C2 and battery C1.

As can be seen from Table 1, when discharging the batteries C1 and C2 until the discharge capacity per unit weight becomes 100 mAh / g, the unit area discharge current is 0.1 and 0.2 mA / cm ² , These battery voltages are all about 2.6 V, and it can be seen that there is no difference between them. On the other hand, when a discharge corresponding to a relatively large unit area discharge current of 0.5 mA / cm ² or more is performed, the battery C1 can keep the battery voltage about 0.4 to 0.5 V higher than the battery voltage of the battery C2. I understand that. That is, in the battery C1, it can be seen that even if the discharge current is increased, the battery voltage does not decrease as much as the battery C2.

As can be seen from the above results, when the battery C1 similar to the battery 100 of the first embodiment is discharged with a discharge current corresponding to a relatively large unit area discharge current of 0.5 mA / cm ² or more, the battery C2 The battery voltage can be kept higher. That is, the lithium ion secondary battery 100 can continuously supply a larger discharge current and electric power (battery voltage) than before. Thus, the positive electrode active material 1 according to the first embodiment can be used for the positive electrode 10 of the lithium ion secondary battery 100 to constitute a battery having high discharge rate characteristics.

Next, a method for producing the positive electrode active material 1 according to Embodiment 1 will be described with reference to FIG.
First, in step S1, Li ₂ O powder Cl, Fe ₂ O ₃ powder Cf, Co ₂ O ₃ powder Cc, V ₂ O ₅ powder Cv, and P ₂ O ₅ powder Cp are mixed at a molar ratio of 2: 1: 1: 2. : Mixed at a ratio of 2. Subsequently, it progressed to step S2 used as a melting process, and this mixed raw material CM was heated and melted at 1000 ° C. for 60 minutes in an electric furnace.
Next, in step S3 which is a solidification process, the molten mixed raw material CM was solidified by rapid cooling. Specifically, the molten mixed raw material CM was poured out on a copper plate that had been cooled in advance in a refrigerator, and rapidly cooled to be vitrified.
Further, in step S4, which is an annealing treatment step, based on the glass transition temperature and melting point of the positive electrode active material 1 having this composition, which has been measured in advance by DTA, these intermediate temperatures, and further the crystallization temperature and melting point The mixture was heated for 200 minutes continuously at an intermediate temperature of 500.degree. C. close to the crystallization temperature.

Thus, the glass comprising lithium-containing iron cobalt vanadium phosphate containing Li, V, and P in addition to Fe and Co by the manufacturing method of the first embodiment including the above-described melting step, solidification step, and annealing step. The positive electrode active material 1 was successfully manufactured.
In the annealing process of the first embodiment, the temperature is maintained at 500 ° C., which is close to the crystallization temperature, at a temperature higher than the glass transition temperature (465 ° C.) and lower than the melting point (600 ° C.). Thereby, the positive electrode active material 1 which has more favorable electric potential conductivity can be manufactured.

(Embodiment 2)
Next, the vehicle 200 equipped with the lithium ion secondary battery 100 will be described. As shown in FIG. 5, this vehicle 200 is a hybrid electric vehicle on which the lithium ion secondary battery 100 is mounted and the wheels 280 are driven by the combined use of the engine 240, the front motor 220, and the rear motor 230. The vehicle 200 is directly or indirectly driven by a vehicle body 270, an engine 240, a front motor 220, a rear motor 230, a cable 250, an inverter 260, a battery pack 210, and the engine 240, the front motor 220, and the rear motor 230 attached thereto. Wheel 280 is provided. Battery pack 210 is attached to vehicle body 270 of vehicle 200. The battery pack 210 includes a plurality of lithium ion secondary batteries 100 that are electrically connected in series, and a charge that controls charging / discharging of the plurality of lithium ion secondary batteries 100, although not shown in detail. A discharge control device 211 is arranged. The charge / discharge control device 211 communicates with, for example, a hybrid system (not shown) on the vehicle 200 side, and the positive electrode 10 using the positive electrode active material of the lithium ion secondary battery 100 according to the instructions of the hybrid system. It has control characteristics that allow discharge with a discharge current corresponding to a unit area discharge current of 0.5 mA / cm ² or more.

Therefore, in the vehicle 200 of the second embodiment, the charge / discharge control device 211 causes the discharge current and power corresponding to a relatively large unit area discharge current of 0.5 mA / cm ² or more from the mounted lithium ion secondary battery 100. (Battery output) can be supplied to the front motor 220 and the rear motor 230 to drive the wheels 280. Therefore, the electric energy of the battery 100 or the combined use with the engine 240 makes it possible to provide the vehicle 200 having good running performance capable of smoothly performing sudden start and acceleration. In addition, by using this battery 100, the controllable discharge current range in the charge / discharge control device 211 can be expanded to the large current side, so that in the vehicle 200, the front motor for driving the wheels 280 by the engine 240 is used. 220, the ratio of driving the wheels 280 by the rear motor 230 can be increased to make the vehicle 200 improved in fuel efficiency.

(Embodiment 3)
Next, a notebook PC 300 equipped with a lithium ion secondary battery 100 using the positive electrode active material 1 according to the first embodiment for the positive electrode 10 will be described. The notebook PC 300 is a battery-equipped device having a battery pack 310 and a main body 320. The battery pack 310 is accommodated in the main body 320 of the notebook PC 300, and a plurality of lithium ion secondary batteries 100 are electrically connected in series and arranged in the battery pack 310, although details are not shown. . Further, a charge / discharge control device 330 that controls charging / discharging of the battery pack 310 is disposed adjacent to the battery pack 310. The charge / discharge control device 330 allows the positive electrode 10 using the positive electrode active material 1 of the lithium ion secondary battery 100 to be discharged with a discharge current corresponding to a unit area discharge current of 0.5 mA / cm ² or more. It has characteristics.
Thus, in the notebook PC 300 according to the third embodiment, even when a large discharge current and power (battery output) are required at a time, such as when starting an external device or a hard disk, the notebook PC 300 can appropriately drive these. It can be.

In the above, the present invention has been described with reference to the first to third embodiments. However, the present invention is not limited to the above-described embodiments and the like, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof. Yes.
For example, in Embodiment 1, lithium-containing iron cobalt vanadium phosphate whose metal M is Co among lithium-containing iron vanadium phosphates is used as the positive electrode active material, but the metal M is Mn or Ni. Iron manganese vanadium phosphate or lithium-containing iron nickel vanadium phosphate may be used. In Embodiment 1, the positive electrode is in the form of a pellet obtained by compression-molding the electrode active material. However, the electrode active material is supported on a current collector (current collector foil) made of a conductive material such as metal. Alternatively, an electrode body or an electrode plate may be used. In the first embodiment, as the power generation element of the battery, a power generation element in which a pair of positive electrodes and negative electrodes are stacked via a separator is used. For example, a stacked type in which a plurality of positive electrodes and negative electrodes are alternately stacked via a separator. Alternatively, a wound-type power generation element obtained by winding a belt-like positive electrode and a negative electrode together through a separator may be used. Furthermore, in Embodiment 1, the shape of the nonaqueous electrolyte secondary battery is a coin-type battery. However, the shape is not limited to this shape. For example, the shape of the power generation element to be used is taken into account. It is good also as a shape.

It is a figure which shows the lithium ion secondary battery concerning Embodiment 1, (a) is a perspective view, (b) is an enlarged longitudinal cross-sectional view. It is a graph which shows the discharge rate characteristic of the lithium ion secondary battery C2 concerning a comparative example (conventional). 3 is a graph showing a discharge rate characteristic of the lithium ion secondary battery C1 according to the first embodiment. 3 is a flowchart showing a method for producing an electrode active material according to Embodiment 1. It is explanatory drawing which shows the vehicle concerning Embodiment 2. FIG. It is explanatory drawing which shows the notebook PC (battery mounting apparatus) concerning Embodiment 3. FIG.

Explanation of symbols

1 Positive electrode active material (electrode active material)
10 Positive electrode (electrode)
100 Lithium ion secondary battery 200 Vehicle 211 Charge / discharge control device (discharge control device)
300 Notebook PC (Battery-equipped device)
330 Charge / Discharge Control Device (Discharge Control Device)
Cc Co ₂ O ₃ powder (compound)
Cf Fe ₂ O ₃ powder (compound)
Cl Li ₂ O powder (compound)
CM mixed raw material (mixture)
Cp P ₂ O ₅ powder (compound)
Cv V ₂ O ₅ powder (compound)

Claims (11)

An electrode active material used for an electrode of a nonaqueous electrolyte secondary battery,
General _{formula: (Li 2 O) a ·} (Fe 2 O 3) b · (M 2 O 3) 0.5-b · (V 2 O 5) c · (P 2 O 5) d (M: Co, Mn, At least one of Ni)
However, 0 <a ≦ 0.5, 0 <b <0.5, 0 <c ≦ 0.5, 0 <d ≦ 0.5
An electrode active material mainly composed of at least one of glass and glass ceramic made of lithium-containing iron vanadium phosphate represented by the formula: An electrode active material used for an electrode of a nonaqueous electrolyte secondary battery,
General _{formula: (Li 2 O) a ·} (Fe 2 O 3) b · (Co 2 O 3) 0.5-b · (V 2 O 5) c · (P 2 O 5) d
However, 0 <a ≦ 0.5, 0 <b <0.5, 0 <c ≦ 0.5, 0 <d ≦ 0.5
An electrode active material mainly composed of at least one of glass and glass ceramics comprising lithium-containing iron cobalt vanadium phosphate represented by the formula: The electrode active material according to claim 1 or 2,
An electrode active material satisfying a = c = d = 0.5 and 0.2 ≦ b ≦ 0.3. The electrode provided with the electrode active material as described in any one of Claims 1-3. A nonaqueous electrolyte secondary battery comprising the electrode according to claim 4. A vehicle comprising the nonaqueous electrolyte secondary battery according to claim 5. The vehicle according to claim 6,
The non-aqueous electrolyte secondary battery is equipped with a discharge control device that allows discharge with a discharge current having a magnitude of 0.5 mA / cm ² or more per unit area of the electrode. The battery mounting apparatus which mounts the nonaqueous electrolyte secondary battery of Claim 5. An electrode active material used for an electrode of a nonaqueous electrolyte secondary battery,
General _{formula: (Li 2 O) a ·} (Fe 2 O 3) b · (M 2 O 3) 0.5-b · (V 2 O 5) c · (P 2 O 5) d (M: Co, Mn, At least one of Ni)
However, 0 <a ≦ 0.5, 0 <b <0.5, 0 <c ≦ 0.5, 0 <d ≦ 0.5
A method for producing an electrode active material mainly comprising at least one of glass and glass ceramics comprising lithium-containing iron vanadium phosphate represented by:
A melting step of heating and melting a mixture in which compounds containing five elements of Li, Fe, M, V, and P are mixed in a predetermined molar ratio;
Then, a solidification step of rapidly cooling and solidifying this,
Thereafter, an annealing treatment step of heating and maintaining the glass transition temperature to a temperature not lower than the melting point and not higher than the melting point, a method for producing an electrode active material. An electrode active material used for an electrode of a nonaqueous electrolyte secondary battery,
General formula: (Li ₂ O) _a · (Fe ₂ O ₃ ) _b · (Co ₂ O ₃ ) _0.5-b · (V ₂ O ₅ ) _c · (P ₂ O ₅ ) _d provided that 0 <a ≦ 0 .5,0 <b <0.5, 0 <c ≦ 0.5, 0 <d ≦ 0.5
A method for producing an electrode active material mainly comprising at least one of glass and glass ceramics comprising lithium-containing iron cobalt vanadium phosphate represented by:
A melting step of heating and melting a mixture in which compounds containing five elements of Li, Fe, Co, V, and P are mixed at a predetermined molar ratio;
Then, a solidification step of rapidly cooling and solidifying this,
Thereafter, an annealing treatment step of heating and maintaining the glass transition temperature to a temperature not lower than the melting point and not higher than the melting point, a method for producing an electrode active material. It is a manufacturing method of the electrode active material according to claim 9 or 10,
The said annealing process process is a manufacturing method of the electrode active material which is a process heated and hold | maintained to the temperature more than crystallization temperature and below melting | fusing point.

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