Lithium iron phosphate ion battery and method for manufacturing lithium iron phosphate ion battery

Abstract

With the present invention, the discharge energy of a lithium iron phosphate ion battery is increased. This method for manufacturing a lithium iron phosphate ion battery involves: a step of forming a positive electrode containing lithium, iron, phosphorus, and amorphous carbon; a step of forming a negative electrode containing graphite and amorphous carbon; and a step of putting the positive electrode, the negative electrode, and a predetermined electrolyte in a predetermined container and sealing the container. At least one of the amorphous carbon of the positive electrode and the amorphous carbon of the negative electrode has a carbon nanotube or a fullerene of 10 wt.% or less.

Description

Lithium iron phosphate battery and method for manufacturing the same

[0001] The present invention relates to a lithium iron phosphate ion battery and a method for manufacturing a lithium iron phosphate ion battery.

[0002] Lithium-ion batteries are known to have high energy density, rapid charge / discharge capability, and are expected to have a long life. Lithium-ion batteries can be constructed using a variety of materials, such as ternary lithium-ion batteries that use nickel, manganese, and cobalt as the positive electrode material, and lithium iron phosphate-ion batteries that use lithium iron phosphate (LFP: LiFePO4) as the positive electrode material (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2017-212045

[0004] Compared to ternary lithium-ion batteries, lithium iron phosphate batteries can be constructed without using rare metals such as cobalt, which reduces manufacturing costs. However, lithium iron phosphate batteries have a problem in that they have lower discharge energy than ternary lithium-ion batteries.

[0005] The present invention has been made in view of these points, and has as its object to increase the discharge energy of a lithium iron phosphate battery.

[0006] In a first aspect of the present invention, there is provided a method for manufacturing a lithium iron phosphate ion battery, comprising the steps of forming a positive electrode containing lithium, iron, phosphorus, and amorphous carbon, forming a negative electrode containing graphite and amorphous carbon, and placing the positive electrode, the negative electrode, and a predetermined electrolyte in a predetermined container and sealing the container, wherein at least one of the amorphous carbon of the positive electrode and the amorphous carbon of the negative electrode contains 10 wt % or less of fullerenes or carbon nanotubes.

[0007] In the step of forming the positive electrode, the positive electrode is formed by applying a positive electrode slurry using a positive electrode material containing lithium iron phosphate and amorphous carbon to a substrate and drying the slurry, and the amorphous carbon of the positive electrode material may contain 10 wt % or less of the fullerene or the carbon nanotube.

[0008] In the step of forming the negative electrode, the negative electrode is formed by applying a negative electrode slurry using a negative electrode material having graphite and amorphous carbon to a substrate and drying the slurry, and the amorphous carbon of the negative electrode material may contain 10 wt % or less of the fullerene or the carbon nanotube.

[0009] At least one of the amorphous carbon of the positive electrode and the amorphous carbon of the negative electrode may contain 5 wt % or less of fullerenes or carbon nanotubes.

[0010] In the step of forming the positive electrode, the positive electrode is formed by applying a positive electrode slurry using a positive electrode material containing lithium iron phosphate and amorphous carbon to a substrate and drying the slurry, and the amorphous carbon of the positive electrode material may contain 5 wt % or less of the fullerene or the carbon nanotube.

[0011] In the step of forming the negative electrode, the negative electrode is formed by applying a negative electrode slurry using a negative electrode material having graphite and amorphous carbon to a substrate and drying the slurry, and the amorphous carbon of the negative electrode material may contain 5 wt % or less of the fullerene or the carbon nanotube.

[0012] In a second aspect of the present invention, there is provided a lithium iron phosphate ion battery comprising: a positive electrode containing lithium, iron, phosphorus, and amorphous carbon; a negative electrode containing graphite and amorphous carbon; and an electrolyte, wherein at least one of the amorphous carbon of the positive electrode and the amorphous carbon of the negative electrode contains 10% by weight or less of fullerenes or carbon nanotubes.

[0013] At least one of the amorphous carbon of the positive electrode and the amorphous carbon of the negative electrode may contain 5 wt % or less of fullerenes or carbon nanotubes.

[0014] The present invention has the effect of increasing the discharge energy of a lithium iron phosphate battery.

[0015] 1 shows an example of a schematic configuration of the lithium iron phosphate ion battery 10 according to the present embodiment. FIG. 2 shows an example of a manufacturing flow for the lithium iron phosphate ion battery 10 according to the present embodiment. FIG. 3 shows an example of a configuration of the lithium iron phosphate ion battery 10 according to the present embodiment. FIG. 4 shows an example of an assembly flow for the lithium iron phosphate ion battery 10 according to the present embodiment. FIG. 5 shows the results of analyzing the conductive additive of the lithium iron phosphate ion battery 10 according to the present embodiment using high performance liquid chromatography. FIG. 6 shows a first example of the charge / discharge characteristics of the lithium iron phosphate ion battery 10 according to the present embodiment. FIG. 7 shows a second example of the charge / discharge characteristics of the lithium iron phosphate ion battery 10 according to the present embodiment. FIG. 8 shows an example of the charge / discharge cycle characteristics of the lithium iron phosphate ion battery 10 according to the present embodiment. FIG. 9 shows an example of the charge / discharge cycle characteristics of the second comparative object.

[0016] 1 shows an example of the schematic configuration of a lithium iron phosphate ion battery 10 according to this embodiment. The lithium iron phosphate ion battery 10 is a rechargeable secondary battery. The lithium iron phosphate ion battery 10 includes a positive electrode 20, a negative electrode 30, a separator 40, an electrolyte 50, and a storage container 60.

[0017] The positive electrode 20 contains lithium, iron, phosphorus, and amorphous carbon. The active material of the positive electrode 20 is lithium iron phosphate. The positive electrode 20 is an electrode formed from, for example, lithium iron phosphate, amorphous carbon, and a binder such as PVDF (Polyvinylidene Difluoride) as positive electrode materials. Here, the amorphous carbon is a conductive additive such as ketjen black or acetylene black. The conductive additive is a material used to reduce the resistance of an electrode when forming an electrode for a lithium-ion battery.

[0018] The negative electrode 30 includes graphite and amorphous carbon. The active material of the negative electrode 30 is graphite. The negative electrode 30 is an electrode formed using, for example, amorphous carbon, a thickener such as CMC (Carboxymethyl Cellulose), and a binder such as SBR (Styrene-Butadiene Rubber) as negative electrode materials.

[0019] The separator 40 separates the positive electrode 20 and the negative electrode 30 while allowing lithium ions to move between the positive electrode 20 and the negative electrode 30. The separator 40 is, for example, a film having a thickness of about several tens of micrometers and having a plurality of through-holes of 1 μm or less. The separator 40 is made of, for example, polyethylene, polypropylene, or the like.

[0020] The electrolyte 50 ionizes lithium into positive and negative ions, allowing the ions to move. The electrolyte 50 is a solvent, solution, gel-like substance, or the like. For example, the electrolyte 50 is an organic electrolytic solution in which approximately 1 mol of a lithium salt (LiPF6, LiBF4, LiClO4, etc.) is dissolved in an organic solvent. Examples of the organic solvent material include ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC).

[0021] The storage container 60 accommodates the positive electrode 20, the negative electrode 30, the separator 40, and the electrolyte 50. The storage container 60 is preferably a container that seals the positive electrode 20, the negative electrode 30, the separator 40, and the electrolyte 50. The storage container 60 has a positive terminal 61 electrically connected to the positive electrode 20 and a negative terminal 62 electrically connected to the negative electrode 30.

[0022] The lithium iron phosphate battery 10 is charged when a power source is connected to the positive terminal 61 and the negative terminal 62. When the lithium iron phosphate battery 10 is charged, electrons move from the positive electrode 20 to the negative electrode 30, and lithium ions pass from the positive electrode 20 through the electrolyte 50 and are stored in the negative electrode 30, thereby generating a potential difference between the positive electrode 20 and the negative electrode 30.

[0023] On the other hand, lithium iron phosphate ion battery 10 discharges when a discharge circuit such as a load is connected to positive terminal 61 and negative terminal 62. When lithium iron phosphate ion battery 10 is discharged, electrons flow from negative electrode 30 to positive electrode 20 through the discharge circuit, and lithium ions stored in negative electrode 30 move to positive electrode 20 through electrolyte 50, where they combine with electrons in positive electrode 20 and are reduced to lithium oxide.

[0024] The lithium iron phosphate battery 10 according to this embodiment improves discharge energy by including fullerenes or carbon nanotubes in at least one of the positive electrode 20 and the negative electrode 30. For example, the lithium iron phosphate battery 10 includes 5 wt % or less of fullerenes or carbon nanotubes in at least one of the amorphous carbon of the positive electrode 20 and the amorphous carbon of the negative electrode 30. The fullerenes may have a C60 structure, or alternatively, may have a C70 structure. Alternatively, the fullerenes may be a mixture of fullerenes with a C60 structure and fullerenes with a C70 structure.

[0025] The inventors have thus found that the inclusion of an appropriate amount of fullerene or carbon nanotubes in the conductive additive serves to further reduce the electrical resistance of the electrode, i.e., the inclusion of an appropriate amount of fullerene or carbon nanotubes in the conductive additive increases the discharge energy of the lithium iron phosphate battery 10.

[0026] The amount of fullerenes or carbon nanotubes is, for example, 1% by weight or more and 5% by weight or less of the amorphous carbon in the electrode. The amount of fullerenes or carbon nanotubes may be 2% by weight or more and 4% by weight or less of the graphite in the electrode, or 2.5% by weight or more and 3.5% by weight or less. A method for manufacturing such a lithium iron phosphate battery 10 will now be described.

[0027] 2 shows an example of a manufacturing flow of the lithium iron phosphate ion battery 10 according to this embodiment. In this embodiment, a coin-type battery will be described as an example of the lithium iron phosphate ion battery 10.

[0028] First, the positive electrode 20 and the negative electrode 30 are formed. For example, the positive electrode 20 and the negative electrode 30 are formed separately. The positive electrode 20 and the negative electrode 30 may be formed in parallel in time, or may be formed at different times. For example, the negative electrode 30 may be formed after the positive electrode 20, or alternatively, the positive electrode 20 may be formed after the negative electrode 30. FIG. 2 shows an example in which the positive electrode 20 and the negative electrode 30 are formed in parallel in time.

[0029] First, the formation of the positive electrode 20 containing lithium, iron, phosphorus, and amorphous carbon will be described. The film composition of the positive electrode 20 is, for example, a 91:4:5 weight ratio of lithium iron phosphate, amorphous carbon, and PVDF. The amorphous carbon of the positive electrode material contains 5 wt. % or less of fullerenes or carbon nanotubes. In this embodiment, 3 wt. % of fullerenes is added to the amorphous carbon.

[0030] More specifically, first, the LFP cathode material of lithium, iron, and phosphorus is vacuum-dried (S81). For example, the LFP cathode material is placed in a vacuum chamber or the like, and a vacuum is created using a vacuum pump, and the LFP cathode material is dried by maintaining the temperature at about 200° C. for about 5 hours.

[0031] Next, PVDF is dissolved in a solvent such as N-methyl pyrrolidone (NMP), a dispersant is added, and the resulting solution is stirred. The dried LFP cathode material and the amorphous carbon doped with fullerenes are then added and stirred to form a cathode slurry (S82). The amount of dispersant is, for example, approximately 2% by weight of the cathode material. NMP is then added to the cathode slurry and stirred to achieve a predetermined concentration. The predetermined concentration is, for example, a solids content of 45% by weight.

[0032] Next, a cathode slurry using a cathode material containing lithium iron phosphate and amorphous carbon is applied to a substrate and dried to form a cathode 20 (S83). The substrate is, for example, aluminum foil with a graphite coating on its surface. The graphite has a thickness of, for example, about 1 μm, and the aluminum foil has a thickness of, for example, about 12 μm. It is desirable to apply a predetermined amount of the cathode slurry to the substrate so that a predetermined dry film thickness is formed. For example, the predetermined dry film thickness is, for example, about 80 μm. The cathode slurry is also desirably applied using a slot die coater or the like.

[0033] The applied positive electrode slurry is dried in air at a temperature of about 110°C for about 15 minutes, for example, to form a coating of the positive electrode material with a dry film thickness. The coating of the positive electrode material is then pressed to form a predetermined thickness. The predetermined thickness is, for example, about 70 μm. The coating of the positive electrode material with such a predetermined thickness is cut into a predetermined shape to form the positive electrode 20.

[0034] Next, the formation of the negative electrode 30 containing graphite and amorphous carbon will be described. The film composition of the negative electrode 30 is, for example, a 93.5:2.5:2:2 weight ratio of graphite, amorphous carbon, CMC, and SBR. The amorphous carbon may be ketjen black, acetylene black, or the like. The amorphous carbon of the negative electrode material contains 5 wt. % or less of fullerenes or carbon nanotubes. In this embodiment, 3 wt. % of fullerenes is added to the amorphous carbon.

[0035] More specifically, first, a negative electrode slurry is formed (S84). For example, a predetermined amount of graphite powder and amorphous carbon is added to an aqueous CMC solution and stirred, and then a predetermined amount of SBR solution is added and stirred to form the negative electrode slurry. The aqueous CMC solution contains, for example, 2 wt% CMC. Distilled water is then added to the negative electrode slurry and stirred until the negative electrode slurry has a predetermined concentration. For example, the predetermined concentration is 40 wt% solids.

[0036] Next, a negative electrode slurry using a negative electrode material containing graphite and amorphous carbon is applied to a substrate and dried to form a negative electrode 30 (S85). The substrate is, for example, copper foil coated with carbon nanotubes on its surface. The carbon nanotubes have a thickness of, for example, about 1 μm, and the copper foil has a thickness of, for example, about 6 μm. It is desirable to apply a predetermined amount of the negative electrode slurry to the substrate so that a predetermined dry film thickness is formed. For example, the predetermined dry film thickness is, for example, about 80 μm. The negative electrode slurry is also desirably applied using a slot die coater or the like.

[0037] The applied negative electrode slurry is dried in air at a temperature of about 80°C for about 10 minutes, for example, to form a coating of the negative electrode material with a dry film thickness. The coating of the negative electrode material is then pressed to form a predetermined thickness. The predetermined thickness is, for example, about 60 μm. The coating of the negative electrode material with such a predetermined thickness is cut into a predetermined shape to form the negative electrode 30.

[0038] After the positive electrode 20 and the negative electrode 30 are formed, the positive electrode 20, the negative electrode 30, and a predetermined electrolyte 50 are placed in a predetermined container and sealed, thereby assembling the lithium iron phosphate ion battery 10 (S86). In this manner, the lithium iron phosphate ion battery 10 can be formed.

[0039] <Configuration Example of Lithium Iron Phosphate-Ion Battery 10> Fig. 3 shows a configuration example of the lithium iron phosphate-ion battery 10 according to this embodiment. Fig. 4 shows an example of an assembly flow for the lithium iron phosphate-ion battery 10 according to this embodiment. In other words, Figs. 3 and 4 are diagrams illustrating details of the operation of S86 for assembling the lithium iron phosphate-ion battery 10 described in Fig. 2.

[0040] The lithium iron phosphate ion battery 10 further includes a case 11, a gasket 12, a spacer 13, a washer 14, and a cap 15. The case 11 and the cap 15 are fitted together to form a container 60. Before assembling the lithium iron phosphate ion battery 10, the positive electrode 20 and the negative electrode 30 are preferably dried using a vacuum chamber or the like. In this case, for example, the positive electrode 20 is dried at approximately 110°C for approximately 8 hours, and the negative electrode 30 is dried at approximately 90°C for approximately 8 hours. The separator 40 is cut into a predetermined shape.

[0041] First, the gasket 12 is attached to the case 11 (S91). Next, the positive electrode 20 is placed in the case 11 (S92). Next, the separator 40 is placed on the positive electrode 20 inside the case 11 (S93). Next, a predetermined amount of electrolyte is dripped onto the separator 40 inside the case 11 using a pipette or the like (S94). As an example, the electrolyte is an organic electrolyte solution in which approximately 1 mole of lithium salt (LiPF6) is dissolved in EC, DMC, and EMC in a weight ratio of 1:1:1. It is desirable that the electrolyte be dripped to such an extent that the positive electrode 20, the negative electrode 30, and the separator 40 are immersed in the electrolyte solution.

[0042] Next, the negative electrode 30 is placed on the separator 40 containing the electrolyte (S95). Next, the spacer 13 is placed on the negative electrode 30 inside the case 11 (S96). Next, the washer 14 is placed on the spacer 13 inside the case 11 (S97). Next, the cap 15 is placed on the gasket 12 attached to the case 11 (S98). Next, pressure is applied from above the cap 15, and the case 11 and the cap 15 are fitted together via the gasket 12 (S99).

[0043] This completes the assembly of the lithium iron phosphate ion battery 10. Note that the assembly steps S91 to S99 are preferably performed in an argon atmosphere or a dry atmosphere with a water dew point of −50° C. or lower. The characteristics of the lithium iron phosphate ion battery 10 thus fabricated will now be described.

[0044] <Example of Characteristics of Lithium Iron Phosphate-Ion Battery 10> Figure 5 shows the results of analyzing the conductive additive (amorphous carbon) of the lithium iron phosphate-ion battery 10 according to this embodiment using high-performance liquid chromatography (HPLC). Figure 5 shows the results of HPLC analysis of a cloudy solution obtained by dissolving 2.1 mg of amorphous carbon in 5 ml of a solvent, o-DCB (ortho-dichlorobenzene), and filtering the resulting solution through a 0.2 μm filter. From a comparison of the peak area values ​​in the analysis results, the content of fullerene C60 and fullerene C70 in the amorphous carbon can be estimated to be approximately 3.5%.

[0045] FIG. 6 shows a first example of the charge / discharge characteristics of the lithium iron phosphate ion battery 10 according to this embodiment. FIG. 6 shows the charge / discharge characteristics of the lithium iron phosphate ion battery 10 fabricated according to the manufacturing and assembly flows described in FIGS. 2 to 4. The horizontal axis of FIG. 6 represents time, and the vertical axis represents voltage. For comparison, FIG. 6 also shows the characteristics of a lithium iron phosphate ion battery in which the amorphous carbon does not contain fullerenes or carbon nanotubes as a "first comparative example." In other words, the first comparative example is a conventional lithium iron phosphate ion battery.

[0046] In Figure 6 , the dotted line indicates the time point after approximately 12 hours (43,200 seconds) have elapsed. Figure 6 shows the results of charging the lithium iron phosphate ion battery 10 and the first comparative example from time 0 to approximately 12 hours later on the time axis, and the results of discharging the lithium iron phosphate ion battery 10 and the first comparative example after approximately 12 hours have elapsed. Figure 6 shows that the lithium iron phosphate ion battery 10 according to this embodiment has a discharge time that is approximately 20% longer than the first comparative example. This indicates that the lithium iron phosphate ion battery 10 can achieve approximately 20% higher discharge energy than a conventional lithium iron phosphate ion battery.

[0047] <Example of Fullerenes or Carbon Nanotubes in an Amount Greater than 5% by Weight> In the lithium iron phosphate battery 10 according to the present embodiment, an example in which at least one of the positive electrode 20 and the negative electrode 30 contains 5% by weight or less of fullerenes or carbon nanotubes has been described above, but the present invention is not limited to this. The amount of fullerenes or carbon nanotubes may be greater than 5% by weight of the amorphous carbon of the electrode. At least one of the amorphous carbon of the positive electrode 20 and the amorphous carbon of the negative electrode 30 contains, for example, 10% by weight or less of fullerenes or carbon nanotubes.

[0048] In this case, for example, the amorphous carbon of the positive electrode material may contain 10% by weight or less of fullerenes or carbon nanotubes. Alternatively, or in addition, the amorphous carbon of the negative electrode material may contain 10% by weight or less of fullerenes or carbon nanotubes.

[0049] Fig. 7 shows a second example of the charge-discharge characteristics of the lithium iron phosphate ion battery 10 according to this embodiment. Fig. 7 shows the charge-discharge characteristics of the lithium iron phosphate ion battery 10 manufactured by adding 10 wt% fullerene to the amorphous carbon positive electrode material and 10 wt% fullerene to the amorphous carbon negative electrode material according to the manufacturing and assembly flows described with reference to Figs. 2 to 4.

[0050] 7 shows that the lithium iron phosphate ion battery 10 containing 10 wt % fullerene in the positive electrode 20 and the negative electrode 30 can increase the discharge energy by about 20% compared to the conventional lithium iron phosphate ion battery, similar to the result of FIG. 6.

[0051] Figure 8 shows an example of the charge / discharge cycle characteristics of the lithium iron phosphate ion battery 10 according to this embodiment. The charge / discharge cycle characteristics are plotted by repeating the charge / discharge cycle as shown in Figure 7 and plotting the discharge current capacity and charge current capacity after each cycle. Figure 8 shows that the lithium iron phosphate ion battery 10 fully functions as a rechargeable battery.

[0052] 9 and 10 show the characteristics of a second comparative battery. The second comparative battery is a lithium iron phosphate battery containing 100% fullerene by weight. In other words, the second comparative battery is a lithium iron phosphate battery that uses fullerene instead of amorphous carbon in the positive and negative electrode materials.

[0053] FIG. 9 shows an example of the charge / discharge characteristics of the second comparative battery. It can be seen that the second comparative battery has a small discharge amount and a steep rise in charge voltage. FIG. 10 shows an example of the charge / discharge cycle characteristics of the second comparative battery. The second comparative battery had lower discharge current capacity and charge current capacity than the lithium iron phosphate battery 10.

[0054] 9 and 10 show that the second comparative example functions more as a capacitor than as a battery. This is thought to be because the low electrical conductivity (or ionic conductivity) of fullerenes reduces the ionic conductivity of the active material, thereby reducing its function as a battery. Therefore, it can be seen that the discharge energy of the lithium iron phosphate battery 10 can be increased by including an appropriate amount of fullerenes or carbon nanotubes, such as 10 wt % or less, in the conductive additive.

[0055] Although the lithium iron phosphate battery 10 according to the present embodiment has been described above as an example of a coin-type battery, the present invention is not limited to this. The lithium iron phosphate battery 10 may have any other structure as long as it uses the positive electrode 20 and / or the negative electrode 30 containing a predetermined amount of fullerene or carbon nanotubes as a conductive additive.

[0056] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by functionally or physically distributing or integrating in any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination also have the effects of the original embodiments.

[0057] REFERENCE SIGNS LIST 10 Lithium iron phosphate battery 11 Case 12 Gasket 13 Spacer 14 Washer 15 Cap 20 Positive electrode 30 Negative electrode 40 Separator 50 Electrolyte 60 Storage container 61 Positive terminal 62 Negative terminal

Claims

1. forming a positive electrode comprising lithium, iron, phosphorus, and amorphous carbon; forming a negative electrode comprising graphite and amorphous carbon; a step of sealing the positive electrode, the negative electrode, and a predetermined electrolyte in a predetermined container; having The amorphous carbon of the positive electrode contains 10% by weight or less of fullerene or 2% by weight to 10% by weight of carbon nanotubes, the amorphous carbon of the negative electrode contains 10% by weight or less of fullerenes or carbon nanotubes; At least one of the following is satisfied: How lithium iron phosphate batteries are manufactured.

2. In the step of forming the positive electrode, a positive electrode slurry using a positive electrode material having lithium iron phosphate and amorphous carbon is applied to a substrate and dried to form the positive electrode; The amorphous carbon of the positive electrode material contains 10% by weight or less of the fullerene or 2% by weight or more and 10% by weight or less of the carbon nanotube. A method for producing the lithium iron phosphate battery according to claim 1.

3. In the step of forming the negative electrode, a negative electrode slurry using a negative electrode material having graphite and amorphous carbon is applied to a substrate and dried to form the negative electrode; The amorphous carbon of the negative electrode material contains 10% by weight or less of the fullerene or the carbon nanotube. The method for producing the lithium iron phosphate ion battery according to claim 1 or 2.

4. the amorphous carbon of the positive electrode contains 5% by weight or less of the fullerene or 2% by weight to 5% by weight of the carbon nanotube; the amorphous carbon of the negative electrode contains 5% by weight or less of the fullerene or the carbon nanotube; At least one of the following is satisfied: A method for producing the lithium iron phosphate battery according to claim 1.

5. In the step of forming the positive electrode, a positive electrode slurry using a positive electrode material having lithium iron phosphate and amorphous carbon is applied to a substrate and dried to form the positive electrode; The amorphous carbon of the positive electrode material contains 5% by weight or less of the fullerene or 2% by weight or more and 5% by weight or less of the carbon nanotube. The method for producing the lithium iron phosphate battery according to claim 4 .

6. In the step of forming the negative electrode, a negative electrode slurry using a negative electrode material having graphite and amorphous carbon is applied to a substrate and dried to form the negative electrode; The amorphous carbon of the negative electrode material contains 5% by weight or less of the fullerene or the carbon nanotube. The method for producing the lithium iron phosphate ion battery according to claim 4 or 5.

7. a positive electrode comprising lithium, iron, phosphorus, and amorphous carbon; a negative electrode including graphite and amorphous carbon; Electrolytes and Equipped with The amorphous carbon of the positive electrode contains 10% by weight or less of fullerene or 2% by weight to 10% by weight of carbon nanotubes, the amorphous carbon of the negative electrode contains 10% by weight or less of fullerenes or carbon nanotubes; At least one of the following is satisfied: Lithium iron phosphate battery.

8. the amorphous carbon of the positive electrode contains 5% by weight or less of the fullerene or 2% by weight to 5% by weight of the carbon nanotube; the amorphous carbon of the negative electrode contains 5% by weight or less of the fullerene or the carbon nanotube; At least one of the following is satisfied:

8. The lithium iron phosphate battery of claim 7.