Formation method of lithium ion battery

Abstract

The invention belongs to the technical field of batteries, and particularly relates to a formation method of a lithium ion battery. By reducing the decomposition voltage of the lithium supplement agent and optimizing segmented charging, the duration time of the whole formation process is remarkably shortened, the production efficiency of battery manufacturing is effectively improved, the energy consumption and the time cost are reduced, and the method has important significance on large-scale industrial production. According to the method, the lithium supplement agent is subjected to refined lithium removal through a low current rate, sufficient and uniform release of active lithium is guaranteed, and meanwhile, a compact and stable SEI film can be formed easily through reasonable segmented current. According to the battery formed by adopting the method, the high initial capacity and the excellent cycle life brought by the lithium supplement technology are obtained, and meanwhile, the interface deterioration risk possibly caused by too long formation time is effectively avoided, so that the comprehensive performance of the battery is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a formation method for lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries have broad application prospects in portable electronic products, power batteries, and energy storage due to their high energy density, long lifespan, and environmental friendliness. However, during the first charge and discharge of lithium-ion batteries, the organic electrolyte will decompose and reduce on the surface of the negative electrode, such as graphite, to form a solid electrolyte interphase (SEI) film. This SEI film continuously consumes lithium from the positive electrode during cycling, resulting in a decrease in the reversible specific capacity of the cell and a reduction in battery cycle life, making it difficult to meet the current market demand for cycle performance.

[0003] Therefore, lithium-ion battery replenishment technology has emerged. Compared to negative electrode replenishment, positive electrode replenishment technology has significant advantages in terms of safety, cost, and compatibility with existing battery processes. The positive electrode replenishment method typically involves mixing the positive electrode replenishing agent with the main material, conductive agent, and binder in a specific ratio during a homogenization process to create a positive electrode slurry. This slurry is then coated with a specific areal density and assembled with the negative electrode sheet to form a battery. The formation process is a crucial and complex manufacturing process that significantly impacts the subsequent performance of lithium-ion batteries. The lithium-ion battery formation process primarily involves the formation of a dense solid electrolyte interface film on the surface of the negative electrode material. Simultaneously, during the constant voltage stage of formation (high voltage, low current), side reactions of the electrolyte occur, affecting battery performance. When using existing formation processes for replenished lithium-ion cells, the cell temperature tends to rise, and the formation time is prolonged, leading to reduced formation efficiency and consequently affecting the efficiency of mass production. Therefore, optimizing the formation method and improving formation efficiency have become key research areas.

[0004] The invention with application publication number CN119495858A provides a method for lithium replenishment formation in batteries. Based on the gas production curve and differential capacity curve, the starting voltage, peak voltage and ending voltage of the lithium replenishment reaction are determined. Formation is carried out by segmented charging and resting, which can control the reaction process of the lithium replenishment material, optimize the battery electrode interface, prevent adverse phenomena such as black spots and lithium plating, and improve the cycle performance of lithium-ion batteries. However, this method is highly dependent on the testing equipment and testing conditions. The optimization of the formation process still requires the application of small-scale experimental data such as pouch or button cells to large-scale production cells such as aluminum-cased cells.

[0005] The invention disclosed in application publication number CN116073000B provides a charging method, apparatus, device, and computer storage medium for secondary batteries. This technical solution detects the state of harmonics (SOH) of the secondary battery when it is at a preset charging node. If the SOH value is low, post-lithiation is performed. After the re-lithiation, if the active lithium content of the secondary battery meets the standard, normal charge-discharge cycles are performed. This allows for the assessment of active lithium loss in the secondary battery and the replenishment of active lithium, extending the cycle life and increasing the energy density of the secondary battery, thereby improving its cycle performance and rate performance. However, this invention primarily addresses the issue of post-lithiation of the battery cell and does not address the problem of improving the formation efficiency of lithium batteries.

[0006] Current research on lithium replenishment technology focuses mainly on the synthesis of lithium replenishment agent materials. There is relatively little research on the application of lithium replenishment agents in lithium-ion batteries, especially on the formation process of lithium replenishment agents. Moreover, existing formation processes have long formation times and low formation efficiency. Summary of the Invention

[0007] This invention aims to provide a lithium-ion battery formation method. This method reduces the formation and delithiation time by optimizing the formation charging current ratio of lithium iron phosphate and lithium replenishing agent, and by forming a lithium replenishing composition with lithium replenishing agent and reducing agent to reduce the decomposition voltage of lithium replenishing agent. The battery obtained by using this formation method can effectively reduce the formation time and improve the formation efficiency while ensuring cycle performance, thereby saving the time cost of battery manufacturing.

[0008] To achieve the above-mentioned objectives, the present invention is implemented through the following technical solution: A method for forming a lithium-ion battery includes the following steps: (a) Provide a lithium-ion battery, wherein the positive electrode material comprises a positive electrode active material, a lithium replenishing agent and a reducing agent; (b) The lithium-ion battery is subjected to segmented charging formation, the segmented charging formation including at least one constant current and constant voltage charging stage at a first current rate, and at least one constant current charging stage at a second current rate lower than the first current rate. The reducing agent is used to reduce the decomposition voltage of the lithium replenishing agent.

[0009] Because lithium replenishers themselves require electrochemical delithiation during the formation stage, and common lithium replenishers (such as lithium nickel oxide) typically have high decomposition voltages, traditional formation processes applied to these batteries often result in significantly prolonged formation times, low efficiency, and potential safety hazards due to prolonged high temperatures. While existing formation processes employ segmented charging or adjust steps based on test data, their focus is often limited to optimizing the charging curve itself or only applicable to small-scale experimental batteries. They fail to fundamentally address the core issue of high decomposition voltage in lithium replenishers, thus resulting in very limited improvements in formation efficiency.

[0010] This invention creates a functional composition by adding a reducing agent and a lithium replenishing agent to the positive electrode, effectively reducing the decomposition voltage of the lithium replenishing agent. This allows the lithium replenishing agent to complete the delithiation reaction at a relatively lower voltage, laying the material foundation for shortening the formation time. Furthermore, this invention designs a segmented charging process. In the high-current constant-current charging stage, most of the delithiation process of the positive electrode active material (such as lithium iron phosphate) is rapidly completed, promoting the effective formation of the initial SEI film and thus improving overall efficiency. In the low-current constant-current charging stage, the lithium replenishing agent modified with the reducing agent is allowed to undergo stable and thorough delithiation, effectively avoiding problems such as aggravated interfacial side reactions, gas generation, or localized overheating caused by excessive current. This ensures maximum lithium replenishment effect and battery interfacial stability.

[0011] This invention reduces the formation and delithiation time by optimizing the formation charging current ratio of lithium iron phosphate and the lithium replenishing agent, and by forming a lithium replenishing composition with the lithium replenishing agent and the reducing agent to lower the decomposition voltage of the lithium replenishing agent. Batteries obtained using this method can reduce formation time and improve formation efficiency while maintaining cycle performance, thus saving time and costs in battery manufacturing.

[0012] Preferably, the segmented charging formation includes the following steps in sequence: S1: Charge at a constant current rate of C1 to charge to capacity Q1; S2: Charge the battery to Q2 using a constant current rate C2, where C2 > C1; S3: Charge the battery to the first cutoff voltage V1 using a constant current and constant voltage rate C3; S4: Charge at a constant current rate C4 to the second cutoff voltage V2, where C4 ≤ C3 and V2 > V1.

[0013] Preferably, after step S4, the following step is also included: S5: Charge at a constant current rate of C5 to the second cutoff voltage V2, where C5 ≤ C4.

[0014] Preferably, after step S5, the following steps are also included: S6: Discharge at a constant current rate C6 to the third cutoff voltage V3, where V3 < V1; S7: Charge at a constant current rate of C7 to charge to capacity Q3.

[0015] Preferably, the current ratio C3 is 0.2~1C, and the current ratio C4 is 0.025~0.2C.

[0016] As a further preferred embodiment, the current multiplier C3 is 0.5C and the current multiplier C4 is 0.1C.

[0017] Preferably, the current ratio C5 is 0.025~0.2C; the current ratio C6 is 0.2~2C; and the current ratio C7 is 0.2~2C.

[0018] As a further preferred embodiment, the current ratio C5 is 0.025C; the current ratio C6 is 0.5C; and the current ratio C7 is 0.5C.

[0019] Preferably, the first cutoff voltage V1 is the main delithiation cutoff voltage of the positive electrode active material, and the second cutoff voltage V2 is the delithiation cutoff voltage of the lithium replenishing agent.

[0020] Preferably, the lithium supplement includes at least one of lithium nickelate, lithium iron phosphate, lithium borate, lithium squaric acid, lithium silicate, lithium oxalate, lithium hydroxide, lithium peroxide, and lithium iron sulfide.

[0021] Preferably, the positive electrode active material is lithium iron phosphate.

[0022] Preferably, the reducing agent includes at least one of selenium and its non-transition metal oxides, sulfur and its non-transition metal oxides, tellurium and its non-transition metal oxides, bismuth and its non-transition metal oxides, phosphorus and its non-transition metal oxides, and sulfided polyacrylonitrile.

[0023] Preferably, the amount of lithium supplementer added accounts for 0.84~1.97% of the total mass of the cathode material, and the amount of reducing agent added accounts for 0.84~1.97% of the total mass of the cathode material.

[0024] As a further preferred embodiment, the amount of lithium supplementer added accounts for 1.97% of the total mass of the cathode material, and the amount of reducing agent added accounts for 0.84% ​​of the total mass of the cathode material.

[0025] Preferably, after at least one stage of segmented charging formation, a settling step is also included.

[0026] Preferably, the pressure provided to the battery during the segmented charging formation process is 0~0.5MPa; the ambient temperature during the segmented charging formation process is 20~60℃.

[0027] A lithium-ion battery is prepared by the formation method of a lithium-ion battery as described above.

[0028] Therefore, the present invention has the following beneficial effects: (1) By reducing the decomposition voltage of the lithium replenishing agent and optimizing segmented charging, the present invention significantly shortens the duration of the entire formation process, effectively improves the production efficiency of battery manufacturing, and reduces energy consumption and time costs, which is of great significance for large-scale industrial production. (2) This invention uses a lower current rate to perform refined delithiation of the lithium replenishing agent, ensuring the full and uniform release of active lithium. At the same time, the reasonable segmented current also helps to form a dense and stable SEI film. The battery formed using this method achieves high initial capacity and excellent cycle life due to the lithium replenishment technology, while effectively avoiding the risk of interface deterioration caused by excessively long formation time, thus greatly improving the overall performance of the battery. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0030] Example 1 This embodiment provides a method for the formation of a lithium-ion battery, a lithium-ion battery and a method for its preparation.

[0031] A method for preparing a lithium-ion battery includes the following steps: (1) Preparation of positive electrode: Lithium iron phosphate (LFP), lithium nickel oxide (Li2NiO2), elemental selenium (Se), conductive carbon black (SP), carbon nanotubes (CNT), and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of LFP:Li2NiO2:Se:SP:CNT:PVDF = 93.69:1.97:0.84:1.0:0.7:1.8. The amount of lithium supplement added accounted for 1.97% of the total mass of the positive electrode material, and the amount of reducing agent added accounted for 0.84% ​​of the total mass of the positive electrode material. The mixture was thoroughly stirred in N-methylpyrrolidone to form a positive electrode slurry. This slurry was coated onto carbon-coated aluminum foil for the positive electrode current collector, and then dried, rolled, and die-cut to obtain the positive electrode sheet.

[0032] (2) Preparation of negative electrode: The negative electrode active material graphite, conductive agent acetylene black, binder styrene-butadiene rubber and thickener sodium carboxymethyl cellulose are thoroughly mixed in deionized water at a mass ratio of 95.9:1:1.8:1.3 to form a uniform negative electrode slurry. This slurry is then coated onto the negative electrode current collector copper foil, and after drying, rolling and die-cutting, the negative electrode sheet is obtained.

[0033] (3) Preparation of lithium-ion batteries: The positive electrode sheet, separator, and negative electrode sheet obtained in step (1) are stacked in sequence, with the separator positioned between the positive and negative electrodes. The stacked electrode sheet and separator are then stacked to obtain a battery cell. The battery cell is placed in a pre-formed aluminum-plastic film, and the electrolyte is injected into the baked battery cell prepared above. Vacuum sealing, high-temperature settling, and formation processes are then performed to obtain a lithium-ion battery.

[0034] A method for forming a lithium-ion battery includes the following steps: (a) Provides a lithium-ion battery as described above, wherein the positive electrode material comprises lithium iron phosphate (LFP) as positive electrode active material, lithium nickel oxide (Li2NiO2) as lithium supplement agent, elemental selenium (Se) as reducing agent, conductive carbon black (SP) as conductive agent, carbon nanotubes (CNT) as conductive agent, and polyvinylidene fluoride (PVDF) as binder. (b) The above-mentioned lithium-ion battery is subjected to segmented charging formation, which includes the following steps in sequence: S1: Charge at a constant current rate of C1=0.05C for 30 minutes until the charge level Q1=2.5% SOC; S2: Charge at a constant current rate of C2=0.1C for 30 minutes until the charge level Q2=7.5% SOC; S3: Charge at a constant current and constant voltage using a current multiplier C3 = 0.5C until the first cutoff voltage V1 = 3.65V; S4: Charge at a constant current rate of C4=0.1C until the second cutoff voltage V2=4.2V; S5: Charge at a constant current rate of C5=0.025C until the second cutoff voltage V2=4.2V; S6: Perform constant current discharge at a current multiplier of C6=0.5C until the third cutoff voltage V3=2.5V; S7: Charge at a constant current rate of C7=0.5C for 48 minutes until the charge level Q3=40% SOC.

[0035] During the segmented charging formation process, the battery is provided with a pressure of 0.2 MPa, the ambient temperature during the segmented charging formation process is 45℃, and each step S4 to S7 requires a 10-minute rest period after completion.

[0036] Example 2 The difference between this embodiment and Embodiment 1 is that: A method for preparing a lithium-ion battery, wherein in step (1), LFP, Li2NiO2, elemental selenium, SP, CNT, and PVDF are mixed in a mass ratio of LFP:Li2NiO2:Se:SP:CNT:PVDF = 93.69:0.84:1.97:1.0:0.7:1.8, wherein the amount of lithium supplementer added accounts for 0.84% ​​of the total mass of the cathode material, and the amount of reducing agent added accounts for 1.97% of the total mass of the cathode material. All other steps are the same as in Example 1.

[0037] Example 3 The difference between this embodiment and Embodiment 1 is that: A method for preparing a lithium-ion battery, wherein in step (1), no reducing agent elemental selenium is added; the mixture is prepared in a mass ratio of LFP:Li2NiO2:SP:CNT:PVDF = 93.69:2.81:1:0.7:1.8. All other steps are the same as in Example 1.

[0038] A method for forming a lithium-ion battery, wherein in step S3, the current rate C3 = 0.2C; in step S4, constant current charging is performed at a current rate C4 = 0.05C until the second cutoff voltage V2 = 4.2V; and in step S5, the current rate C5 = 0C. All other steps are the same as in Example 1.

[0039] Example 4 The difference between this embodiment and embodiment 3 is as follows: A method for forming a lithium-ion battery, wherein in step S4, constant current charging is performed at a current rate C4 = 0.1C until a second cutoff voltage V2 = 4.2V. All other steps are the same as in Example 3.

[0040] Example 5 The difference between this embodiment and embodiment 3 is as follows: A method for forming a lithium-ion battery, wherein in step S4, constant current charging is performed at a current rate C4 = 0.2C until a second cutoff voltage V2 = 4.2V. All other steps are the same as in Example 3.

[0041] Example 6 The difference between this embodiment and embodiment 3 is as follows: A method for forming a lithium-ion battery, wherein in step S3, constant current and constant voltage charging is performed at a current rate C3 = 0.5C to a first cutoff voltage V1 = 3.65V; and in step S4, constant current charging is performed at a current rate C4 = 0.025C to a second cutoff voltage V2 = 4.2V. All other steps are the same as in Example 3.

[0042] Example 7 The difference between this embodiment and embodiment 6 is that: A method for forming a lithium-ion battery, wherein in step S3, constant current and constant voltage charging is performed at a current rate C3=1C until a first cutoff voltage V1=3.65V. All other steps are the same as in Example 6.

[0043] Example 8 The difference between this embodiment and embodiment 3 is as follows: A method for forming a lithium-ion battery, wherein in step S3, constant current and constant voltage charging is performed at a current rate C3 = 0.5C until a first cutoff voltage V1 = 3.65V; in step S4, constant current charging is performed at a current rate C4 = 0.1C until a second cutoff voltage V2 = 4.2V; and in step S5, the current rate C5 = 0.025C. All other steps are the same as in Example 3.

[0044] Comparative Example 1 The difference between this comparative example and Example 1 is as follows: A method for forming a lithium-ion battery, wherein in step S3, constant current and constant voltage charging is performed at a current rate C3 = 0.2C to a first cutoff voltage V1 = 3.65V; and in step S4, constant current charging is performed at a current rate C4 = 0.025C to a second cutoff voltage V2 = 4.2V. All other steps are the same as in Example 1.

[0045] Comparative Example 2 The difference between this comparative example and Example 1 is as follows: A method for forming a lithium-ion battery, wherein in step S3, constant current and constant voltage charging is performed at a current rate C3=1C to a first cutoff voltage V1=3.65V; in step S4, constant current charging is performed at a current rate C4=0.2C to a second cutoff voltage V2=4.2V. All other steps are the same as in Example 1.

[0046] Comparative Example 3 The difference between this comparative example and Example 2 is as follows: A method for forming a lithium-ion battery, wherein in step S4, constant current charging is performed at a current rate C4 = 0.025C until a second cutoff voltage V2 = 4.2V. All other steps are the same as in Example 2.

[0047] [Performance Testing and Analysis] Lithium-ion batteries were prepared according to the methods described in Examples 1-8 and Comparative Examples 1-3, respectively, and their performance was tested as follows. The test methods are as follows: (1) Transformation time: The formation time is defined as the sum of the times used for formation and charging in steps S1 to S5 of a lithium-ion battery formation method. The formation times in each embodiment and comparative example were statistically analyzed, and the test results are shown in Table 1 below.

[0048] (2) Loop testing: The lithium-ion batteries prepared in each embodiment and comparative example were charged at a constant power of 0.5P to the charging cutoff voltage of 3.65V, left to stand for 5 minutes, and then discharged at a constant power of 0.5P to the discharging cutoff voltage of 2.5V, left to stand for 5 minutes. This was the first charge-discharge cycle. The batteries were subjected to cyclic charge-discharge tests according to this method. The ratio of discharge capacity to charge capacity in the cyclic test is the cycle capacity retention rate. The test results are shown in Table 1 below.

[0049] Table 1: Test number Charging capacity (mAh / g) Discharge capacity (mAh / g) Conversion time (min) Capacity retention rate after 1000 cycles (%) Example 1 171.5 154.2 379 106.4% Example 2 167.1 153.7 388 105.0% Example 3 172.2 151.9 456 106.8% Example 4 171.3 150.9 422 106.6% Example 5 170.2 151.5 403 106.5% Example 6 171.8 151.7 423 106.4% Example 7 168.5 148.8 364 104.7% Example 8 171.8 154.6 398 106.7% Comparative Example 1 170.6 150.6 433 105.6% Comparative Example 2 163.7 145.5 330 102.6% Comparative Example 3 172.5 151.7 520 106.8%

[0050] Analysis of the data in Table 1 shows that: the present invention uses a stepped rate charging in steps S1 to S3 to ensure the dense and stable growth of the SEI film during the formation process; constant current charging in steps S1 and S2 is used to obtain a stable SEI film; constant current and constant voltage charging in step S3 is used to alleviate cell polarization; steps S4 to S5 help decompose the lithium replenishing agent and ensure that the lithium replenishing agent can be fully activated; in step S7, if the SOC is too low or too high, it will not be conducive to the stability of the properties and composition of the SEI film during aging. Therefore, the charge Q2 is set to 40% SOC. At this time, the battery is in the voltage plateau, which helps to avoid the battery capacity decay during aging caused by excessive decomposition reaction of electrolyte on the negative electrode.

[0051] Comparing Examples 3-5 with Comparative Example 3, it can be found that the smaller the current ratio C4, that is, the smaller the delithiation current of the lithium replenishing agent Li2NiO2, the higher the charging capacity of the cell, and the more complete the delithiation of the lithium replenishing agent. However, the longer the formation time, the cycle performance is positively correlated with the degree of delithiation of the lithium replenishing agent. That is, the more lithium replenishing agent delithiation, the better the cycle performance, but the difference is not significant and can be considered to be basically consistent.

[0052] Comparing Examples 6 / 7 with Comparative Example 3, it can be found that the smaller the third current factor C3, i.e. the smaller the lithium iron phosphate charging current, the higher the charging capacity and the slightly better cycle performance; however, compared with Comparative Example 3, the cell performance of Example 6 can be considered to be basically the same, with a more obvious time advantage and improved formation efficiency.

[0053] Based on the advantages and disadvantages of Examples 3 to 7, the formation method of Example 8 was developed. By comparing Example 8 with Comparative Example 3, it is shown that the formation method listed in Example 8 can reduce the formation time while ensuring the cycle performance of the battery cell by optimizing the formation charging current ratio of lithium iron phosphate and lithium replenishing agent.

[0054] Comparing Example 1 with Comparative Example 1 / 2, it can be seen that Example 1 can also reduce the formation time while ensuring cycle performance and specific capacity, indicating that when using the lithium replenishment composition, the step-rate charging formation method adopted in Example 8 is still the best among all formation methods.

[0055] Comparing Examples 1 / 2 and Example 8, it can be found that when the lithium replenishing agent and the reducing agent are used in a suitable ratio, the formation time is significantly reduced. The reducing agent with excellent electronic conductivity can establish an excellent conductive electronic network with the lithium replenishing agent, which is conducive to the reaction between the lithium replenishing agent and the conductive reducing agent, improves the electrochemical decomposition kinetics of the lithium replenishing agent, reduces the decomposition potential of the lithium replenishing agent, fully exerts the lithium replenishing effect of the lithium replenishing agent, reduces the lithium replenishing agent formation and delithiation time, and improves the formation efficiency of the lithium replenishing battery.

[0056] The above description is merely a detailed explanation of preferred embodiments and principles of the present invention. For those skilled in the art, there may be changes in specific implementation methods based on the ideas provided by the present invention, and these changes should also be considered within the scope of protection of the present invention.

Claims

1. A method for forming a lithium-ion battery, characterized in that, Includes the following steps: (a) Provide a lithium-ion battery, wherein the positive electrode material comprises a positive electrode active material, a lithium replenishing agent and a reducing agent; (b) The lithium-ion battery is subjected to segmented charging formation, the segmented charging formation including at least one constant current and constant voltage charging stage at a first current rate, and at least one constant current charging stage at a second current rate lower than the first current rate. The reducing agent is used to reduce the decomposition voltage of the lithium replenishing agent.

2. The formation method of a lithium-ion battery according to claim 1, characterized in that, The segmented charging process includes the following steps in sequence: S1: Charge at a constant current rate of C1 to charge to capacity Q1; S2: Charge the battery to Q2 using a constant current rate C2, where C2 > C1; S3: Charge the battery to the first cutoff voltage V1 using a constant current and constant voltage ratio C3; S4: Charge at a constant current rate C4 to the second cutoff voltage V2, where C4 ≤ C3 and V2 > V1.

3. The formation method of a lithium-ion battery according to claim 2, characterized in that, Following step S4, the following steps are also included: S5: Charge at a constant current rate of C5 to the second cutoff voltage V2, where C5 ≤ C4.

4. The formation method of a lithium-ion battery according to claim 3, characterized in that, Following step S5, the following steps are also included: S6: Discharge at a constant current rate C6 to the third cutoff voltage V3, where V3 < V1; S7: Charge at a constant current rate of C7 to charge to capacity Q3.

5. The formation method of a lithium-ion battery according to claim 2, characterized in that, The current multiplier C3 is 0.2~1C, and the current multiplier C4 is 0.025~0.2C.

6. The formation method of a lithium-ion battery according to claim 4, characterized in that, The current multiplier C5 is 0.025~0.2C; the current multiplier C6 is 0.2~2C; and the current multiplier C7 is 0.2~2C.

7. The formation method of a lithium-ion battery according to claim 1, characterized in that, The lithium supplementer includes at least one of lithium nickelate, lithium iron phosphate, lithium borate, lithium squaric acid, lithium silicate, lithium oxalate, lithium hydroxide, lithium peroxide, and lithium iron sulfide; the positive electrode active material is lithium iron phosphate; the reducing agent includes at least one of selenium and its non-transition metal oxides, sulfur and its non-transition metal oxides, tellurium and its non-transition metal oxides, bismuth and its non-transition metal oxides, phosphorus and its non-transition metal oxides, and polyacrylonitrile sulfur.

8. A method for forming a lithium-ion battery according to claim 1 or 7, characterized in that, The amount of lithium supplementer added accounts for 0.84~1.97% of the total mass of the cathode material, and the amount of reducing agent added accounts for 0.84~1.97% of the total mass of the cathode material.

9. The formation method of a lithium-ion battery according to claim 1, characterized in that, After at least one stage of segmented charging formation, a settling step is also included.

10. The formation method of a lithium-ion battery according to claim 1, characterized in that, The pressure provided to the battery during the segmented charging formation process is 0~0.5MPa; the ambient temperature during the segmented charging formation process is 20~60℃.