Method for manufacturing high safety carbon material

Abstract

This invention provides a method for manufacturing a high-safety carbon material, comprising: step (A), mixing carbon material, coating material, glutaraldehyde, and a solution at a weight ratio of 100:2-6:0.2-0.6:100-300 to form a mixed slurry, wherein the carbon material is soft carbon and / or artificial graphite, and the coating material is chitosan and / or sulfurized chitosan; step (B), stirring the mixed slurry evenly and heating it at 70°C-90°C to form a evaporated slurry; step (C), heating the evaporated slurry at 70°C-90°C for more than 24 hours, and then cooling it to room temperature to form a high-safety carbon material. The method of this invention helps to obtain a high-safety carbon material that can mitigate the large amount of heat released during the decomposition of the solid electrolyte interfacial film, prevent the heat generated by the decomposition of the solid electrolyte interfacial film from triggering the entire thermal runaway mechanism, and improve the safety of the negative electrode material in battery use.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a high-safety carbon material. Background Technology

[0002] In recent years, carbon materials such as soft carbon and artificial graphite have become prominent battery materials due to their high electrical capacity and long lifespan, especially as anode materials for lithium-ion batteries.

[0003] Next, during the first charge and discharge of a lithium-ion battery, the electrode material and the electrolyte react at the solid-liquid interface to form a passivation layer with solid electrolyte characteristics, generally called a solid electrolyte interface (SEI) film (or simply SEI film), which makes an important contribution to improving the cycle life of the battery.

[0004] On the other hand, battery safety during use is a crucial issue that cannot be ignored in the development of high-energy or high-capacity lithium-ion batteries. When a battery catches fire or explodes, it is theoretically known as thermal runaway, which seriously affects the safety of the battery during use.

[0005] Generally, thermal runaway occurs when a battery experiences abnormal heating during charging and discharging due to a short circuit or electrical imbalance (meaning low capacity or high internal resistance). Once the battery exceeds the critical temperature for thermal runaway (typically around 150°C), the internal materials undergo exothermic thermal decomposition. In particular, if thermal decomposition occurs at the SEI film, it will cause the SEI film to decompose and generate a large amount of exothermic heat, thus triggering the entire thermal runaway mechanism.

[0006] Therefore, there is still room for improvement in how to mitigate the large amount of heat released during SEI film decomposition, prevent the heat generated by SEI film decomposition from triggering the entire thermal runaway mechanism, and thus improve the safety of anode materials in battery use. Summary of the Invention

[0007] The inventors have discovered that by adding chitosan or sulfonated chitosan as a polymer coating material, it is beneficial to deposit a designed and commercially viable artificial solid electrolyte interface (A-SEI) film (hereinafter referred to as A-SEI film) onto the surface of carbon materials, thereby obtaining a highly safe carbon material. This highly safe carbon material helps improve the fast-charging capability and cycle life (capacity retention) of lithium-ion batteries, further mitigates the large amount of heat released during SEI film decomposition, prevents the heat generated by SEI film decomposition from triggering the entire thermal runaway mechanism, and improves the safety of the negative electrode material in battery use, thus completing this invention.

[0008] To address the aforementioned problems, the present invention provides a method for manufacturing a high-safety carbon material, comprising: step (A), mixing carbon material, coating material, glutaraldehyde, and a solution at a weight ratio of 100:2-6:0.2-0.6:100-300 to form a mixed slurry, wherein the carbon material is soft carbon and / or artificial graphite, and the coating material is chitosan and / or sulfurized chitosan; step (B), stirring the mixed slurry evenly and heating it at 70°C-90°C to form a evaporated slurry; and step (C), heating the evaporated slurry at 70°C-90°C for at least 24 hours, followed by cooling to room temperature to form the high-safety carbon material.

[0009] In one embodiment, after step (C), a step (D) is further included, in which the high-safety carbon material is sieved through a sieve with a mesh size of less than 38 micrometers and the undersize is obtained.

[0010] In one embodiment, compared to the carbon material, the high-safety carbon material has a capacity retention rate that is improved by more than 40% after 120 5C charge-discharge cycles.

[0011] In one embodiment, the heat release of the SEI exothermic peak of the high-safety carbon material after 120 5C charge-discharge cycles is less than 7.5 J / g.

[0012] In one embodiment, the high-safety carbon material obtained in step (A) using the sulfurized chitosan exhibits an exothermic SEI peak of less than 5.5 J / g after 120 charge-discharge cycles at 5C.

[0013] In one embodiment, compared to the carbon material, the high-safety carbon material improves the fast charging capability by more than 3% under 2C fast charging conditions and by more than 3% under 5C fast charging conditions.

[0014] In one embodiment, the cumulative irreversible efficiency (AIE) of the high-safety carbon material after 200 charge-discharge cycles at 0.3C is less than 88.5%.

[0015] In one embodiment, compared to the carbon material, the high-safety carbon material has a capacity retention rate that is improved by more than 2% after 100 charge-discharge cycles at 0.3C.

[0016] In one embodiment, when testing according to the SAE J2464 standard method under the conditions of a puncture needle diameter of 3 mm, a puncture speed of 8 cm / min, and a minimum puncture depth of penetrating the battery cell, the positive electrode is LiNi. 0.8 Mn 0.1 Co 0.1 O2 and the negative electrode are composed of the aforementioned high-safety carbon material, forming a soft-pack battery with a capacity of 1Ah, which can pass the puncture test.

[0017] In one embodiment, in step (A), the solution is water or water containing 2% acetic acid by volume.

[0018] This invention addresses the aforementioned well-known problems and aims to provide a method for manufacturing a high-safety carbon material that improves the safety of the negative electrode material in battery use. Specifically, by adding chitosan or sulfur-based chitosan as a polymer coating material, an artificial A-SEI film is deposited on the carbon material surface. This helps to mitigate the large amount of heat released during SEI film decomposition, prevents the heat generated by SEI film decomposition from triggering the entire thermal runaway mechanism, and improves the safety of the negative electrode material in battery use. Attached Figure Description

[0019] Figure 1 This is a flowchart of the manufacturing method of the high-safety carbon material of the present invention.

[0020] Figure 2 To show a photograph of Control Example 1 10 seconds after the puncture test.

[0021] Figure 3 To show a photograph of Test Case 1 18 seconds after the puncture test. Detailed Implementation

[0022] The following describes the implementation of the present invention through specific embodiments. Those skilled in the art can understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0023] Unless otherwise stated herein, the term "A to B" as used in the specification and appended claims includes the meaning of "more than A and less than B". For example, the term "10 to 40% by weight" includes the meaning of "more than 10% by weight and less than 40% by weight".

[0024] First, please refer to Figure 1 , Figure 1 This is a flowchart illustrating the manufacturing method of the high-safety carbon material of the present invention. (For example...) Figure 1 As shown, the method for manufacturing the high-safety carbon material of the present invention includes steps (A) to (C). Furthermore, in one embodiment, step (D) may be further included after step (C), if necessary. Each step will be described in detail below.

[0025] Step (A)

[0026] Step (A) involves mixing carbon material, coating material, glutaraldehyde, and solution at a weight ratio of 100:2–6:0.2–0.6:100–300 to form a mixed slurry. The carbon material can be granular soft carbon and / or artificial graphite; the coating material can be chitosan and / or sulfurized chitosan. Chitosan and sulfurized chitosan are high-molecular-weight polymers with excellent thermal stability. The sulfonate groups generated after sulfonation facilitate lithium-ion transfer. Combined with glutaraldehyde (GA) as a crosslinking agent, chitosan or sulfurized chitosan undergoes a crosslinking reaction with glutaraldehyde to form a stable polymeric artificial solid electrolyte interface (A-SEI) coating the carbon material.

[0027] In some specific examples, the weight ratio of carbon material: chitosan: glutaraldehyde: solution can be 100:2:0.2:100, 100:4:0.4:100, or 100:6:0.6:100, etc. On the other hand, in some specific examples, the weight ratio of carbon material: sulfurized chitosan: glutaraldehyde: solution can be 100:2:0.2:300 or 100:4:0.4:300, etc. Furthermore, from the viewpoint of easy and uniform mixing, the weight ratio of carbon material to solution (carbon material: solution) is preferably between 1:1 and 1:3.

[0028] Next, the solution can be water or water containing 2% acetic acid by volume. Furthermore, the carbon material, chitosan or sulfurized chitosan, glutaraldehyde, and solution can all be commercially available materials, such as soft carbon produced by CPC Corporation or artificial graphite (trade name MGP) purchased from China Steel Carbon Corporation, without particular restrictions. Through step (A), the carbon material can be uniformly dispersed in the solution, and through subsequent steps, the chitosan or sulfurized chitosan undergoes a cross-linking reaction with glutaraldehyde to form an A-SEI film coating the carbon material.

[0029] Step (B)

[0030] Step (B) involves stirring the mixed slurry obtained in step (A) until homogeneous and heating it at 70°C to 90°C to form a dried slurry. Specifically, step (B) can be performed by placing the mixed slurry obtained in step (A) into a round-bottom flask, placing it on a heating plate, continuously stirring it at 300 rpm until homogeneous, and heating it at 80°C until the slurry is completely evaporated (the solution is removed) to form a dried slurry. Step (B) enables the coating of carbon materials with chitosan or sulfurized chitosan.

[0031] Step (C)

[0032] Step (C) involves heating the evaporated slurry obtained in step (B) at 70°C–90°C for at least 24 hours, followed by cooling to room temperature to form a highly safe carbon material. Specifically, step (C) may involve removing the carbon material (evaporated slurry) coated with chitosan or sulfurized chitosan from the cylindrical flask, placing it in a vacuum oven, and drying it at 80°C for 24 hours (or treating it in a horizontal furnace tube purged with nitrogen at a rate of 10°C per minute to 80°C for 24 hours) to facilitate the cross-linking reaction between chitosan or sulfurized chitosan and glutaraldehyde. The material is then cooled to room temperature (either naturally or by cooling) to form a coated A-SEI film on the carbon material, thereby obtaining a highly safe carbon material. Through step (C), chitosan or sulfurized chitosan undergoes a cross-linking reaction with glutaraldehyde to form a highly safe carbon material with a stable A-SEI film.

[0033] Step (D)

[0034] Step (D) is an optional step used to screen out high-safety carbon materials with appropriate particle size for subsequent application as anode materials. Specifically, step (D) may involve sieving the high-safety carbon materials through a sieve with a mesh size of 38 micrometers (400 mesh) or smaller and obtaining the undersize material.

[0035] Example

[0036] The present invention will be specifically described below through various embodiments and comparative examples, but the present invention is not limited to these embodiments and comparative examples.

[0037] Preparation of high-safety carbon materials

[0038] Preparation Example 1

[0039] Based on steps (A) to (C) above, the high-safety carbon material 1 of Preparation Example 1 is obtained. In step (A), the weight ratio of soft carbon: chitosan: glutaraldehyde: solution is 100:2:0.2:100. Furthermore, the soft carbon used is PPSC series soft carbon purchased from CPC Corporation, Taiwan; the chitosan used is product number 419419 purchased from SIGMA-ALDRICH; the glutaraldehyde used is product number 49629 purchased from SIGMA-ALDRICH; and the solution is water containing 2% acetic acid by volume.

[0040] Preparation Examples 2-3

[0041] Except for adjusting the weight ratio of soft carbon: chitosan: glutaraldehyde: solution to 100:4:0.4:100 and 100:6:0.6:100 respectively, high-safety carbon materials 2-3 were obtained in the same manner as in Preparation Example 1.

[0042] Preparation Example 4

[0043] Based on steps (A) to (C) above, the high-safety carbon material 4 of Preparation Example 4 was obtained. In step (A), the weight ratio of soft carbon: sulfurized chitosan: glutaraldehyde: solution was 100:2:0.2:300. Furthermore, the soft carbon used was PPSC series soft carbon purchased from CPC Corporation, Taiwan; the sulfurized chitosan was further synthesized using chitosan (product number 419419) purchased from SIGMA-ALDRICH; the glutaraldehyde used was product number 49629 purchased from SIGMA-ALDRICH; and the solution used was water.

[0044] Preparation Example 5

[0045] Except for adjusting the weight ratio of soft carbon: sulfurized chitosan: glutaraldehyde: solution to 100:4:0.4:300, high-safety carbon material 5 was obtained in the same manner as in Preparation Example 4.

[0046] Reference Example 1

[0047] Soft carbon was used as carbon material A in Reference Example 1.

[0048] Example 1

[0049] The high-safety carbon material 1 of Preparation Example 1 was prepared by using it and subjecting it to the above-described step (D).

[0050] Specifically, the negative electrode material 1 is a uniform mixture of 950g of high-safety carbon material 1, 30g of sodium alginate (purchased from ACROS, trade number: 177772500), and 20g of conductive agent (conductive carbon black, purchased from Timcal, trade name Super P) as the negative electrode material. Next, the negative electrode material is mixed with 1233g to 1438g of N-methylpyrrolidone (NMP) to form a mixture. This mixture is then coated onto a copper foil with a thickness of 14μm and dried at 85°C for 0.5 hours to remove NMP and moisture, thus forming the negative electrode of the full cell. The negative electrode includes the copper foil and a conductive film formed on the copper foil with a thickness of 100μm to 110μm. Next, using manual stacking, a negative electrode, a positive electrode, an electrolyte, and a separator (brand: Celgard, material: PP, thickness: 20μm) are assembled into a full cell (length × width × height: 4cm × 2cm × 0.2cm, cell capacity: 0.15Ah~0.2Ah).

[0051] On the other hand, the positive electrode of the full cell includes an aluminum foil as a conductive carrier and a conductive film formed on the surface of the aluminum foil. The conductive film of the positive electrode of the full cell comprises 92.5 wt% lithium nickel cobalt manganese oxide (LNMC, capacity ≥150 mAh / g), 2.5 wt% PVDF, and 5 wt% conductive carbon black (purchased from Timcal, trade name Super P). The electrolyte comprises 97 wt% 1.2 M LiPF6 solution, 1 wt% vinylene carbonate (VC), and 2 wt% 1,3-propanesulfonyl lactone (PS). The LiPF6 solution comprises LiPF6, EC, EMC, and diethyl carbonate (DEC), and the volume ratio of EC:EMC:DEC is 1:3:2. Next, the capacity retention rate and fast charging capability under 2C and 5C charge-discharge cycles were tested using a charge-discharge machine (manufacturer: Maccor, model: Series 4000). The fast charging conditions were: charging / discharging: constant current, charge-discharge rate (C-rate): constant current / 0.1C (constant current + constant voltage) and the test results are shown in Tables 1 and 2 below.

[0052] Examples 2-5

[0053] Except for using the high-safety carbon materials 2-5 from Examples 2-5, the full cells of Examples 2-5 were obtained in the same manner as in Example 1. Next, the capacity retention rate and fast-charging capability of Examples 2-5 were tested in the manner described above, and the test results are shown in Tables 1-2 described below.

[0054] Comparative Example 1

[0055] Except for using carbon material A as in Reference Example 1, a full cell of Comparative Example 1 was obtained in the same manner as in Example 1. Next, the capacity retention rate and fast charging capability of Comparative Example 1 were tested in the manner described above, and the test results are shown in Tables 1 to 2 described below.

[0056] Table 1

[0057]

[0058] Table 2

[0059]

[0060] As shown in Table 1 above, compared to the carbon material A of Comparative Example 1, which has a fast charging capability of 56% (capable of fully charging 56% of the battery capacity) under 2C fast charging conditions, the high-safety carbon materials 1-3 of Examples 1-3 have a fast charging capability of over 60% under 2C fast charging conditions. In other words, using the chitosan-coated carbon material of Examples 1-3, the fast charging capability under 2C fast charging conditions is improved by more than 3%, and even by about 7%. Furthermore, compared to the carbon material A of Comparative Example 1, which has a fast charging capability of 38% under 5C fast charging conditions, the high-safety carbon materials 1-3 of Examples 1-3 have a fast charging capability of over 40%, and even reaching 50%, under 5C fast charging conditions. In other words, as shown in Table 1 above, compared to Comparative Example 1 using carbon material A, the high-safety carbon materials 1-3 of Examples 1-3 using chitosan-coated carbon material have a fast charging capability improved by more than 3%, and even by about 12%, under 5C fast charging conditions.

[0061] Furthermore, as can be seen from Table 2 above, under the condition of 120 charge-discharge cycles at 5C, compared to the 25% capacity retention rate of carbon material A in Comparative Example 1, the high-safety carbon materials 2 and 4 to 5 in Examples 2 and 4 to 5 also have a capacity retention rate of over 40% after 120 charge-discharge cycles at 5C. Moreover, the capacity retention rate of Examples 4 to 5 using sulfurized chitosan can reach over 70%, indicating that the effect of using sulfurized chitosan is better than that of using chitosan.

[0062] Next, it can be seen from Table 2 above that, compared with Comparative Example 1 which uses carbon material A, the high-safety carbon materials 4-5 of Examples 4-5 which use carbon material coated with sulfurized chitosan have a capacity retention rate that is increased by more than 40%, or even by about 50%, after 120 charge-discharge cycles at 5C.

[0063] Test of heat release from SEI exothermic peak

[0064] For the full cells of Comparative Example 1 and Examples 2, 4-5 above, the heat release of the SEI exothermic peak after 120 cycles of 5C charge-discharge at a heating rate of 5°C / min (fully charged) was calculated, and the results are summarized in Table 3 below.

[0065] Here, heat release equals the thermal power per unit mass integrated over time.

[0066] For example, when measuring heat release using DSC, the thermal power (flow) Cp differs at temperatures T1 and T2. The unit of thermal power (flow) Cp is J / min × g. Given a heating rate of 5℃ / min, T1 corresponds to time t1, and T2 corresponds to time t2. The heat release... That is, ΔH is approximately equal to J / g.

[0067] Table 3

[0068]

[0069]

[0070] As can be seen from Table 3 above, compared to the heat release of carbon material A in Comparative Example 1, which is 46.9 J / g, the heat release of the SEI exothermic peak of high-safety carbon materials 2 and 4 to 5 after 120 cycles of 5C charge-discharge is less than 7.5 J / g. Moreover, the heat release of Examples 4 to 5 using sulfurized chitosan can achieve an even better result of less than 5.5 J / g. It can be seen that the present invention can significantly reduce the large amount of heat release during SEI film decomposition.

[0071] Accumulated Irreversible Capacity (AIE) Test

[0072] For the full cells of Comparative Example 1 and Examples 4-5 above, an AIE test was performed after 200 charge-discharge cycles at 0.3C with a heating rate of 5°C / min; that is, the coulombic efficiency of each cycle was accumulated to calculate the total loss of coulombic efficiency, and the results are summarized in Table 4 below.

[0073] Table 4

[0074]

[0075] As shown in Table 4 above, compared to the carbon material A of Comparative Example 1, which has an AIE of 88.8%, the high-safety carbon materials 4-5 of Examples 4-5 have an AIE of less than 88.5% after 200 charge-discharge cycles at 0.3C, achieving an even better result of approximately 77.7%.

[0076] Preparation Example 6

[0077] Based on steps (A) to (C) above, the high-safety carbon material 6 of Preparation Example 6 is obtained. In step (A), the weight ratio of artificial graphite: sulfurized chitosan: glutaraldehyde: solution is 100:2:0.2:300. Furthermore, the artificial graphite is YPG01 or CY92S graphite purchased from CPC Corporation, Taiwan; the sulfurized chitosan is chitosan (product number 419419) purchased from SIGMA-ALDRICH and further synthesized in-house; the glutaraldehyde is product number 49629 purchased from SIGMA-ALDRICH; and the solution is water.

[0078] Preparation Example 7

[0079] Except for adjusting the weight ratio of artificial graphite: chitosan sulfide: glutaraldehyde: solution to 100:4:0.4:300, high-safety carbon material 7 was obtained in the same manner as in Preparation Example 6.

[0080] See Example 2

[0081] Artificial graphite was used as carbon material B in Reference Example 2.

[0082] Examples 6-7

[0083] Except for using the high-safety carbon materials 6-7 from Preparation Examples 6-7, the full cells of Examples 6-7 were obtained in the same manner as in Example 1. Next, the capacity retention rate under 0.3C charge-discharge cycles was tested using a charge-discharge machine (manufacturer: Maccor, model: Series 4000), and the test results are shown in Table 5 described later.

[0084] Comparative Example 2

[0085] Except for using carbon material B as in Reference Example 2, a full cell of Comparative Example 2 was obtained in the same manner as in Example 1. Next, the capacity retention rate of Comparative Example 2 was tested in the manner described above, and the test results are shown in Table 5 described later.

[0086] Table 5

[0087]

[0088] As shown in Table 5 above, compared to the 89.6% capacity retention rate of carbon material B in Comparative Example 2, the high-safety carbon materials 6-7 of Examples 6-7 achieved a capacity retention rate of over 91% after 100 charge-discharge cycles at 0.3C. This demonstrates that, in addition to applying sulfidated chitosan (or chitosan) to soft carbon, applying sulfidated chitosan (or chitosan) to artificial graphite can also achieve improved capacity retention and mitigate the significant exothermic reaction during SEI film decomposition. Furthermore, Table 5 shows that, compared to Comparative Example 2 using carbon material B, the high-safety carbon materials 6-7 of Examples 6-7, using carbon material coated with sulfidated chitosan, showed a capacity retention rate increase of over 2%, and even approximately 3%, after 100 charge-discharge cycles at 0.3C.

[0089] Puncture test

[0090] Compare with Example 1

[0091] The SAE J2464 standard method was used for testing under the conditions of a 3mm needle diameter, a puncture speed of 8cm / min, and a minimum puncture depth of penetrating the battery cell. In the 1Ah pouch cell, the positive electrode used was LiNi. 0.8 Mn 0.1 Co 0.1 O2 (theoretical capacity of 200 mAh / g), negative electrode using 90 wt% artificial graphite + 10 wt% soft carbon, separator using PE, and electrolyte the same as in Example 1 above. The results of the puncture test, as follows... Figure 2 As shown, Figure 2 To show the photograph of Control Example 1 after 10 seconds of puncture test, it can be seen that the negative electrode of Control Example 1 ignited and exploded after 10 seconds, which means it failed the puncture test.

[0092] Test Example 1

[0093] Except for the negative electrode, which used 90 wt% of the high-safety carbon material 6 from Preparation Example 6 and 10 wt% of the high-safety carbon material 4 from Preparation Example 4, the other processes were performed in the same manner as Control Example 1, using the SAE J2464 standard method. The results of the puncture test, as shown... Figure 3 As shown, Figure 3 The photo shows Test Example 1 after 18 seconds of puncture testing. It can be seen that the negative electrode of Test Example 1 did not ignite after 18 seconds, which means it passed the puncture test.

[0094] It can be seen that, regardless of whether artificial graphite or soft carbon is used as the substrate, by cross-linking chitosan or sulfurized chitosan with glutaraldehyde, a stable A-SEI film can be formed on carbon materials such as artificial graphite or soft carbon, thereby enabling the high-safety carbon material manufactured by this invention to pass the puncture test.

[0095] Based on this, the method of the present invention helps to obtain a high-safety carbon material that can slow down the large amount of heat released during SEI film decomposition, prevent the heat generated by SEI film decomposition from triggering the entire thermal runaway mechanism, and improve the safety of the negative electrode material in battery use.

[0096] This invention is not limited to the above-described embodiments. Various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of this invention.

Claims

1. A method for manufacturing a high-safety carbon material, characterized in that, Include: Step (A) involves mixing carbon material, coating material, glutaraldehyde, and solution in a weight ratio of 100:2-6:0.2-0.6:100-300 to form a mixed slurry, wherein the carbon material is soft carbon and / or artificial graphite, and the coating material is chitosan and / or sulfurized chitosan. Step (B): The mixed slurry is stirred evenly and heated at 70°C to 90°C to form a evaporated slurry; Step (C) involves heating the evaporated slurry at 70°C to 90°C for more than 24 hours, and then cooling it to room temperature to form a highly safe carbon material.

2. The method for manufacturing high-safety carbon materials according to claim 1, characterized in that, Following step (C), the method further includes step (D), which involves sieving the high-safety carbon material through a sieve with a mesh size of 38 micrometers or less and obtaining the undersize material.

3. The method for manufacturing high-safety carbon materials according to claim 1 or 2, characterized in that, Compared to the carbon material, the high-safety carbon material has a capacity retention rate that is improved by more than 40% after 120 charge-discharge cycles at 5C.

4. The method for manufacturing high-safety carbon materials according to claim 1 or 2, characterized in that, The heat release of the SEI exothermic peak of the high-safety carbon material after 120 cycles of 5C charge-discharge is less than 7.5 J / g.

5. The method for manufacturing high-safety carbon materials according to claim 1 or 2, characterized in that, The high-safety carbon material obtained by using the sulfurized chitosan in step (A) has an exothermic SEI peak of less than 5.5 J / g after 120 charge-discharge cycles at 5C.

6. The method for manufacturing high-safety carbon material according to claim 1 or 2, characterized in that, Compared to the carbon material, the high-safety carbon material improves the fast charging capability by more than 3% under 2C fast charging conditions and by more than 3% under 5C fast charging conditions.

7. The method for manufacturing high-safety carbon materials according to claim 1 or 2, characterized in that, The high-safety carbon material has a cumulative irreversible capacity of less than 88.5% after 200 charge-discharge cycles at 0.3C.

8. The method for manufacturing high-safety carbon materials according to claim 1 or 2, characterized in that, Compared to the carbon material, the high-safety carbon material has a capacity retention rate that is improved by more than 2% after 100 charge-discharge cycles at 0.3C.

9. The method for manufacturing high-safety carbon material according to claim 1 or 2, characterized in that, Under the conditions of a 3mm needle diameter, a puncture speed of 8cm / min, and a minimum puncture depth of penetrating the battery cell, the SAE J2464 standard method is applied to the positive electrode, which uses LiNi. 0.8 Mn 0.1 Co 0.1 O2 and the negative electrode are composed of the aforementioned high-safety carbon material, forming a soft-pack battery with a capacity of 1Ah, which can pass the puncture test.

10. The method for manufacturing high-safety carbon material according to claim 1 or 2, characterized in that, In step (A), the solution is water or water containing 2% acetic acid by volume.

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