Lithium iron phosphate battery and method for manufacturing the same

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

[Technical field]

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

[0002] Lithium ion batteries are known to have a high energy density, are capable of rapid charging and discharging, and are expected to have a long life. It is also known that lithium ion batteries can be made of various 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). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-212045 A Summary of the Invention [Problem to be solved by the invention]

[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 consideration of these points, and has an object to increase the discharge energy of a lithium iron phosphate battery. [Means for solving the problem]

[0006] In a first aspect of the present invention, there is provided a method for producing 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 it, wherein at least one of the amorphous carbon of the positive electrode and the amorphous carbon of the negative electrode has 10% by weight or less of fullerenes or carbon nanotubes.

[0007] 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, and the amorphous carbon of the positive electrode material may contain 10% by weight or less of the fullerene or the carbon nanotube.

[0008] 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, and the amorphous carbon of the negative electrode material may contain 10% by weight or less of the fullerene or the carbon nanotube.

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

[0010] 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, and the amorphous carbon of the positive electrode material may contain 5% by weight or less of the fullerene or the carbon nanotube.

[0011] 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, and the amorphous carbon of the negative electrode material may contain 5% by weight 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 has 10% by weight or less of fullerenes or carbon nanotubes.

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

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

[0015] [Figure 1] 1 shows an example of a schematic configuration of a lithium iron phosphate battery 10 according to the present embodiment. [Diagram 2] An example of a manufacturing flow of the lithium iron phosphate battery 10 according to this embodiment will be described below. [Diagram 3] 1 shows an example of the configuration of a lithium iron phosphate battery 10 according to this embodiment. [Figure 4] An example of an assembly flow for the lithium iron phosphate battery 10 according to this embodiment will be described below. [Diagram 5] The results of analyzing the conductive assistant of the lithium iron phosphate ion battery 10 according to this embodiment using a high performance liquid chromatograph are shown. [Figure 6] 1 shows a first example of charge / discharge characteristics of the lithium iron phosphate battery 10 according to this embodiment. [Figure 7] 2 shows a second example of the charge / discharge characteristics of the lithium iron phosphate battery 10 according to the present embodiment. [Figure 8] 4 shows an example of the charge / discharge cycle characteristics of the lithium iron phosphate battery 10 according to this embodiment. [Figure 9] 13 shows an example of charge / discharge characteristics of a second comparative subject. [Figure 10] 4 shows an example of charge / discharge cycle characteristics of a second comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] <General configuration of lithium iron phosphate battery 10> 1 shows an example of a schematic configuration of a lithium iron phosphate battery 10 according to this embodiment. The lithium iron phosphate battery 10 is a rechargeable secondary battery. The lithium iron phosphate 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 includes 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 by using, for example, lithium iron phosphate, amorphous carbon, and a binder such as PVDF (Poly Vinylidene Difluoride) as a positive electrode material. Here, the amorphous carbon is a conductive assistant such as Ketjen Black or Acetylene Black. The conductive assistant is a material used to reduce the resistance of an electrode when forming an electrode of 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 μm and a plurality of through holes of 1 μm or less. The separator 40 is formed 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, a solution, a gel-like substance, or the like. The electrolyte 50 is, for example, an organic electrolytic solution in which about 1 mol of a lithium salt (LiPF6, LiBF4, LiClO4, or the like) is dissolved in an organic solvent. The material of the organic solvent is, for example, ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or the like.

[0021] The storage container 60 stores the positive electrode 20, the negative electrode 30, the separator 40, and the electrolyte 50. The storage container 60 is desirably 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 ion 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 ion 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, the lithium iron phosphate ion battery 10 discharges when a discharge circuit such as a load is connected to the positive terminal 61 and the negative terminal 62. When the lithium iron phosphate ion battery 10 is discharged, electrons flow from the negative electrode 30 to the positive electrode 20 through the discharge circuit, and the lithium ions stored in the negative electrode 30 move to the positive electrode 20 through the electrolyte 50 and combine with the electrons in the positive electrode 20 to be reduced to lithium oxide.

[0024] The lithium iron phosphate ion 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 ion battery 10 has 5% by weight 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. Here, the fullerenes may have a C60 structure, or alternatively, may have a C70 structure. The fullerenes may also 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 nanotube in the conductive assistant serves to reduce the electrical resistance of the electrode, i.e., the discharge energy of the lithium iron phosphate battery 10 increases when an appropriate amount of fullerene or carbon nanotube is included in the conductive assistant.

[0026] The amount of fullerene or carbon nanotube is, for example, 1% by weight or more and 5% by weight or less of the amorphous carbon of the electrode. The amount of fullerene or carbon nanotube may be 2% by weight or more and 4% by weight or less of the graphite of 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 be described below.

[0027] <Manufacturing flow for lithium iron phosphate battery 10> 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. As an example, the film composition of the positive electrode 20 is a weight ratio of lithium iron phosphate, amorphous carbon, and PVDF of 91:4:5. The amorphous carbon of the positive electrode material contains 5% by weight or less of fullerene or carbon nanotube. In this embodiment, 3% by weight of fullerene 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 five hours.

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

[0032] Next, a positive electrode slurry using a positive electrode material containing lithium iron phosphate and amorphous carbon is applied to a substrate and dried to form a positive electrode 20 (S83). The substrate is, for example, an aluminum foil with a graphite-coated 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 positive electrode slurry to the substrate so that a predetermined dry film thickness is formed. For example, the predetermined dry film thickness is about 80 μm. It is also desirable to apply the positive electrode slurry 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 to form a coating film of the positive electrode material with a dry thickness. The coating film of the positive electrode material is then pressed to form a predetermined thickness. The predetermined thickness is, for example, about 70 μm. The coating film 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. As an example, the film composition of the negative electrode 30 is a weight ratio of graphite, amorphous carbon, CMC, and SBR of 93.5:2.5:2:2. The amorphous carbon is Ketjen black, acetylene black, etc. The amorphous carbon of the negative electrode material has 5% by weight or less of fullerene or carbon nanotube. In this embodiment, 3% by weight of fullerene 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 solution of CMC and stirred, and a predetermined amount of SBR solution is further added and stirred to form a negative electrode slurry. The aqueous solution of CMC contains, for example, 2% by weight of CMC. Then, distilled water is added to the negative electrode slurry and stirred so that the negative electrode slurry has a predetermined concentration. For example, the predetermined concentration is 40% by weight of solids.

[0036] Next, a negative electrode slurry using a negative electrode material having graphite and amorphous carbon is applied to a substrate and dried to form a negative electrode 30 (S85). The substrate is, for example, a copper foil having a surface coated with carbon nanotubes. 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. The predetermined dry film thickness is, for example, about 80 μm. It is also desirable to apply the negative electrode slurry 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 to form a coating film of the negative electrode material with a dry thickness. The coating film of the negative electrode material is then pressed to form a predetermined thickness. The predetermined thickness is, for example, about 60 μm. The coating film 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 battery 10> Fig. 3 shows an example of the configuration of the lithium iron phosphate battery 10 according to this embodiment. Also, Fig. 4 shows an example of an assembly flow of the lithium iron phosphate battery 10 according to this embodiment. In other words, Figs. 3 and 4 are diagrams for explaining details of the operation of S86 for assembling the lithium iron phosphate 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, it is preferable to dry the positive electrode 20 and the negative electrode 30 using a vacuum chamber or the like. In this case, as an example, the positive electrode 20 is dried at about 110° C. for about 8 hours, and the negative electrode 30 is dried at about 90° C. for about 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 in the case 11 (S93). Next, a predetermined amount of electrolyte is dropped onto the separator 40 in the case 11 with a pipette or the like (S94). As an example, the electrolyte is an organic electrolyte in which about 1 mole of lithium salt (LiPF6) is dissolved in EC, DMC, and EMC in a weight ratio of 1:1:1. It is desirable to drop the electrolyte to such an extent that the positive electrode 20, the negative electrode 30, and the separator 40 are immersed in the electrolyte.

[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 it is desirable to perform the assembly operations from S91 to S99 in an argon atmosphere or in a dry atmosphere with a water dew point of −50° C. or lower. The characteristics of the lithium iron phosphate ion battery 10 thus assembled will now be described.

[0044] <Example of characteristics of lithium iron phosphate battery 10> Fig. 5 shows the results of analyzing the conductive assistant (amorphous carbon) of the lithium iron phosphate ion battery 10 according to this embodiment using a high performance liquid chromatograph (HPLC). Fig. 5 shows the results of HPLC analysis of 2.1 mg of amorphous carbon dissolved in 5 ml of a solvent o-DCB (ortho-dichlorobenzene) and filtered through a 0.2μ filter to obtain a cloudy solution. From a comparison of the peak area values ​​of the analysis results, the content of fullerene C60 and fullerene C70 components contained in the amorphous carbon can be estimated to be about 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 produced according to the manufacturing flow and assembly flow described in FIG. 2 to FIG. 4. The horizontal axis of FIG. 6 indicates time, and the vertical axis indicates 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 object." In other words, the first comparative object is a conventional lithium iron phosphate ion battery.

[0046] In Fig. 6, the point when about 12 hours (43200 seconds) have passed is indicated by a dotted line. Fig. 6 shows the results of charging the lithium iron phosphate ion battery 10 and the first comparative example from 0 on the time axis until about 12 hours later, and shows the results of discharging the lithium iron phosphate ion battery 10 and the first comparative example after about 12 hours have passed. It can be seen from Fig. 6 that the discharge time of the lithium iron phosphate ion battery 10 according to this embodiment is increased by about 20% compared to the first comparative example. This shows that the lithium iron phosphate ion battery 10 can increase the discharge energy by about 20% compared to a conventional lithium iron phosphate ion battery.

[0047] <Examples of fullerenes or carbon nanotubes with a weight percentage greater than 5%> In the lithium iron phosphate battery 10 according to the present embodiment, an example has been described 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, 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 have 10% by weight or less of fullerenes or carbon nanotubes. Alternatively or in addition, the amorphous carbon of the negative electrode material may have 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 produced by adding 10% by weight of fullerene to the amorphous carbon positive electrode material and 10% by weight of fullerene to the amorphous carbon negative electrode material according to the production flow and assembly flow described with reference to Figs. 2 to 4.

[0050] FIG. 7 shows that the lithium iron phosphate battery 10 containing 10% by weight of fullerene in the positive electrode 20 and the negative electrode 30 can achieve a discharge energy that is approximately 20% higher than that of a conventional lithium iron phosphate battery, similar to the results of FIG. 6.

[0051] Fig. 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 shown as a result of repeating charge / discharge cycles as shown in Fig. 7 and plotting the discharge current capacity and the charge current capacity after each cycle. Fig. 8 shows that the lithium iron phosphate ion battery 10 fully functions as a rechargeable battery.

[0052] 9 and 10 show the characteristics of the second comparative example. The second comparative example is a lithium iron phosphate ion battery in which the mixed amount of fullerene is 100% by weight. In other words, the second comparative example is a lithium iron phosphate ion battery in which fullerene is used 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 example. It can be seen that the second comparative example has a small discharge amount and a steep rise in charging voltage. FIG. 10 shows an example of the charge / discharge cycle characteristics of the second comparative example. The second comparative example had a lower discharge current capacity and a lower charging current capacity than the lithium iron phosphate battery 10.

[0054] 9 and 10, it can be seen that the second comparative example functions more as a capacitor than as a battery. This is thought to be because the electric conductivity (or ionic conductivity) of fullerene is low, which reduces the ionic conductivity in the active material and reduces the battery's functionality. 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 fullerene or carbon nanotubes, such as 10% by weight or less, in the conductive assistant.

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

[0056] Although the present invention has been described above using the embodiments, 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 distributing or integrating functionally or physically in any unit. In addition, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment resulting from the combination combines the effect of the original embodiment. [Explanation of symbols]

[0057] 10 Lithium iron phosphate battery 11 Cases 12 Gasket 13 Spacer 14 Washer 15 Cap 20 positive electrode 30 negative electrode 40 Separator 50 electrolytes 60 Containment 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 has fullerenes of 5% or less by weight of the amorphous carbon of the positive electrode; The amorphous carbon of the negative electrode has fullerenes of 10% or less by weight of the amorphous carbon of the negative electrode. 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 the fullerenes in an amount of 5% by weight or less of the amorphous carbon of the positive electrode. 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 the fullerene in an amount of 10% by weight or less of the amorphous carbon of the negative electrode. The method for producing the lithium iron phosphate ion battery according to claim 1 or 2.

4. the amorphous carbon of the negative electrode has 5% or less of the fullerene by weight of the amorphous carbon of the negative electrode; A method for producing the lithium iron phosphate battery according to claim 1.

5. 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 of the amorphous carbon of the negative electrode. The method for producing the lithium iron phosphate battery according to claim 4 .

6. 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 has fullerenes of 5% or less by weight of the amorphous carbon of the positive electrode; The amorphous carbon of the negative electrode has fullerenes of 10% or less by weight of the amorphous carbon of the negative electrode. Lithium iron phosphate battery.

7. the amorphous carbon of the negative electrode has 5% or less of the fullerene by weight of the amorphous carbon of the negative electrode; 7. The lithium iron phosphate battery of claim 6.

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