Lithium-rich manganese-based battery and activation method and application thereof

Abstract

The invention provides a lithium-rich manganese-based battery and an activation method and application thereof, and the activation method comprises the following steps: standing the lithium-rich manganese-based battery, then charging, and then discharging to cut-off voltage to complete activation; in the discharging process, the I1 current density is adopted for discharging when the voltage is within the range of 3.3 V to 3.0 V, the I2 current density is adopted for discharging when the rest voltage ranges are larger than 3.3 V and smaller than 3.0 V, and I1 is smaller than I2. According to the activation method disclosed by the invention, the current is accurately regulated and controlled in a specific interval of 3.3-3.0 V, so that the phase change behavior and interface reaction of the lithium-rich manganese-based material are accurately regulated and controlled, the advantage of high theoretical specific capacity of the lithium-rich manganese-based material is fully exerted, the bottleneck that the capacity of the lithium-rich manganese-based material is difficult to reach over 300mAh / g under high voltage is broken through, and the performance of the lithium-rich manganese-based material is improved. And meanwhile, the structural stability of the lithium-rich manganese-based material is also ensured.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a lithium-rich manganese-based battery, its activation method, and its application. Background Technology

[0002] Lithium-ion batteries are widely used in portable electronic devices due to their high energy density, long cycle life, and environmental friendliness, and they also show promising application prospects in the field of large-scale power batteries. Lithium-rich manganese-based cathode materials, with their ultra-high theoretical specific capacity (300-400 mAh / g), excellent cost-effectiveness, and environmental compatibility, are widely recognized as core candidate materials for next-generation high-energy-density lithium-ion batteries, demonstrating broad application prospects in power batteries and energy storage systems. However, significant technical bottlenecks still exist in the practical application of this material, and its performance potential has not yet been fully explored.

[0003] From the perspective of current technology, the application scenarios of lithium-rich manganese-based cathode materials are mostly concentrated in the low-to-medium voltage range (such as below 4.55V). Within this range, the research focus is mainly on modification methods such as doping, coating, and morphology control to optimize the cycle stability and structural reliability of the materials. However, the low voltage window severely limits the deep insertion / extraction of lithium ions and the full release of oxygen activity in the materials, making it difficult to translate their theoretical high capacity potential into practical application performance, and significantly weakening the intrinsic advantages of the materials.

[0004] Despite attempts to push lithium-rich manganese-based materials to higher voltage ranges (e.g., 4.6V and above) to unlock their capacity potential, current technologies have yielded unsatisfactory results. Even under high voltage conditions, the reversible specific capacity of these materials remains mostly at 250-280 mAh / g, failing to break the critical threshold of 300 mAh / g. The core reason for this capacity bottleneck lies in the lack of in-depth understanding of the lithium-ion re-intercalation mechanism. It is generally believed that high voltages can lead to drastic structural phase transitions (such as the irreversible transformation of layered structures into rock-salt phase structures), intensified interfacial side reactions, and the dissolution of transition metal ions, resulting in rapid voltage decay and deteriorated cycle stability. This situation not only restricts the competitiveness of lithium-rich manganese-based materials in high-energy-density battery systems but also prevents the full realization of their core advantages as next-generation high-capacity cathodes.

[0005] Based on the above research, there is a need to provide an activation method for lithium-rich manganese-based batteries. This activation method can improve the capacity of lithium-rich manganese-based cathode materials under high voltage, achieving a breakthrough in reversible capacity of over 300 mAh / g, thus enabling the practical application of high-energy-density lithium-ion batteries. Summary of the Invention

[0006] The purpose of this invention is to provide a lithium-rich manganese-based battery, its activation method and application. The activation method, by precisely controlling the phase transition behavior and interface reaction of the lithium-rich manganese-based material, enables the lithium-rich manganese-based material to fully utilize its high theoretical specific capacity advantage, breaking through the bottleneck that the lithium-rich manganese-based material is difficult to achieve a capacity of more than 300 mAh / g under high voltage, while also ensuring the structural stability of the lithium-rich manganese-based material.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides an activation method for a lithium-rich manganese-based battery, the activation method comprising the following steps:

[0009] The lithium-rich manganese-based battery is left to stand, then charged, and then discharged to the cutoff voltage to complete the activation.

[0010] During the discharge process, the discharge is carried out using a current density of I1 when the voltage is in the range of 3.3V-3.0V, and the discharge is carried out using a current density of I2 when the voltage range is >3.3V and <3.0V, where I1 < I2.

[0011] The differences between ternary cathode materials and lithium-rich manganese-based materials are as follows: From the fundamental differences in material structure and capacity characteristics, the maximum lithium intercalation capacity of the layered structure of ternary cathode materials is only 278 mAh / g, and its crystal structure fundamentally limits the possibility of exceeding 300 mAh / g in specific capacity. In contrast, the crystal structure of lithium-rich manganese-based materials has unique advantages. They are considered to be single-phase solid solutions of R-3m or C2 / m phases, or nanocomposites of two phases: LiTMO2 (R-3m space group) and Li2MnO3 (C2 / m space group). Both structures indicate that the lithium ion proportion in the transition metal (TM) layer of the Li2MnO3 phase reaches 1 / 3. It is known that during charging of lithium-rich manganese-based materials, lithium ions in the TM layer can be successfully extracted under voltage activation; however, during discharge, these lithium ions are difficult to re-intercalate to their original sites. The inherent lithium intercalation limit of the layered structure is 290 mAh / g, therefore, the problem of the re-intercalation path for excess lithium ions needs to be solved.

[0012] The solution to the problem of excess lithium ion re-intercalation pathways is directly related to the current control in the 3.3V-3.0V range during discharge. The reason is as follows: during discharge, the reduction kinetics of manganese ions are poor, and lithium ion diffusion lag easily occurs at high current densities, leading to reaction inhibition. This invention, by using low current density discharge in the 3.3V-3.0V range, can effectively reduce the kinetic barrier, provide sufficient time for lithium ion diffusion, and promote Mn... 4+Fully reduced; meanwhile, the stable voltage range of the spinel phase is 3.5-5.0V. When the voltage drops to the 3.3V-3.0V range, the octahedral interstices of the spinel phase can provide additional lithium intercalation sites for lithium ions. Current regulation in this range can further promote the transformation of the layered structure of lithium-rich manganese-based materials into the spinel structure, laying the structural foundation for improving the discharge specific capacity.

[0013] Furthermore, this invention chooses to use low-current discharge only in the 3.3V-3.0V range, rather than using low-current discharge throughout, primarily to avoid structural damage and uncontrolled phase transition. While using low-current discharge throughout could improve the initial discharge specific capacity, it would continuously promote Mn production. 4+ To Mn 3+ Transformation, excess Mn 3+ Disproportionation reactions can easily occur, leading to material structural collapse. If a small current is maintained below 3.0V, an irreversible transformation from the spinel phase to the rock salt phase will be induced, ultimately causing material failure. Therefore, using a large current in the voltage range >3.3V can reduce excessive manganese participation in this stage by increasing the kinetic barrier of manganese reduction; maintaining a large current discharge in the voltage range <3.0V can effectively suppress the transformation from the spinel phase to the rock salt phase, thereby ensuring capacity improvement while maintaining material structural stability.

[0014] In summary, this invention uses a low current density for discharge in the voltage range of 3.3V-3.0V, and a high current density for discharge in the voltage ranges above 3.3V and below 3.0V. This not only improves the capacity but also ensures the structural stability of the material.

[0015] It is understood that the lithium-rich manganese-based battery described in this invention refers to a battery whose positive electrode material is a lithium-rich manganese-based material.

[0016] Preferably, I1 is below 0.1C, for example, it can be 0.1C, 0.075C, 0.05C, 0.025C, 0.01C, 0.0075C or 0.005C, and I2 is above 0.1C, for example, it can be 0.1C, 0.15C, 0.2C, 0.25C, 0.3C, 0.35C, 0.4C, 0.45C or 0.5C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] Preferably, I2 / I1 ≥ 1.5, for example, it can be 1.5, 2.5, 3.5, 4.5, 5.5, 6.5 or 7.5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] Preferably, the discharge process includes: discharging the lithium-rich manganese-based battery at a current density of I2; when the voltage drops to 3.3V, reducing the current density to I1 to discharge to 3.0V; and then restoring the current density to I2 to continue discharging to the cutoff voltage.

[0019] Where I1 is 0.005C-0.1C, for example, it can be 0.1C, 0.075C, 0.05C, 0.025C, 0.01C, 0.0075C or 0.005C, and I2 is 0.1C-0.5C, for example, it can be 0.1C, 0.15C, 0.2C, 0.25C, 0.3C, 0.35C, 0.4C, 0.45C or 0.5C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] In this invention, discharge is preferably performed at a specific low current density within the voltage range of 3.3V-3.0V. If the current density in this range is too high, although the current density has been reduced relative to I2, it is still greater than 0.1C. This will cause lithium ion insertion and extraction to be too fast at high rates, leading to lattice stress cracking. Furthermore, the polarization voltage at high current may cause electrolyte decomposition, and the high capacity performance of the material cannot be fully utilized at high rates. If the current density in this range is too low, lithium ions may slowly and unevenly deposit on the surface of the negative electrode, forming lithium dendrites.

[0021] In this invention, I2 and I1 are not both 0.1C.

[0022] Preferably, during the discharge process, the discharge current density is the same in the voltage range >3.3V and the voltage range <3.0V.

[0023] Preferably, the voltage range for charging and discharging is 2.0-4.8V, that is, the present invention uses a high current density discharge of I2 in the range of 4.8V-3.3V (excluding 3.3V) and 3.0V-2.0V (excluding 3.0V), and uses a low current density discharge of I1 in the range of 3.3V-3.0V.

[0024] Preferably, the charging current density is 0.1C-0.5C, for example, it can be 0.1C, 0.15C, 0.2C, 0.25C, 0.3C, 0.35C, 0.4C, 0.45C or 0.5C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the device is allowed to stand after charging before being discharged.

[0026] Preferably, the temperature for allowing the lithium-rich manganese-based battery to stand is 40-60°C, for example, 40°C, 50°C or 60°C, and the time is 18-22h, for example, 18h, 19h, 20h, 21h or 22h, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Before activating the lithium-rich manganese-based battery, the present invention places the battery in a specific temperature environment and lets it stand for a period of time to promote the full wetting and contact between the electrolyte and the positive electrode material, so as to ensure the effective construction of the ion conduction path.

[0028] Preferably, the lithium-rich manganese-based battery includes a positive electrode and a negative electrode, wherein the positive electrode includes a lithium-rich manganese-based positive electrode material with the general chemical formula Li. x Mn a Ni b Co c M d O 1+x Where 1 < x ≤ 2, for example, it can be 1.1, 1.3, 1.5, 1.7, 1.9 or 2; 0.5 ≤ a ≤ 1, for example, it can be 0.5, 0.6, 0.7, 0.8, 0.9 or 1; 0 ≤ b ≤ 0.5, for example, it can be 0, 0.1, 0.2, 0.3, 0.4 or 0.5; 0 ≤ c ≤ 0.5, for example, it can be 0, 0.1, 0.2, 0.3, 0.4 or 0.5; 0 ≤ d ≤ 0.5, for example, it can be 0, 0.1, 0.2, 0.3, 0.4 or 0.5; 0 < a + b + c + d ≤ 1, for example, it can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1; and M is selected from any one or at least a combination of two of Co, Al, Mo, Mg, Fe, Nb, W, Zr, Ti or Cu.

[0029] The lithium-rich manganese-based material of the present invention uses manganese, a relatively inexpensive and abundant element, as its main component, which significantly reduces the dependence on expensive and scarce metals such as cobalt and nickel.

[0030] Preferably, the negative electrode sheet comprises a lithium metal sheet or a graphite negative electrode sheet.

[0031] In a second aspect, the present invention provides a lithium-rich manganese-based battery, which is obtained by activation using the activation method described in the first aspect.

[0032] Thirdly, the present invention provides an electronic device comprising a lithium-rich manganese-based battery as described in the second aspect.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) This invention precisely controls the phase change and interface reaction of materials by regulating the current density of the discharge process, breaking through the capacity bottleneck of existing lithium-rich manganese-based materials that are difficult to reach 300mAh / g under high voltage, and improving the energy density of the battery.

[0035] (2) This invention reduces the kinetic barrier of manganese ion reduction by precisely controlling the current within a specific range of 3.3V-3.0V, thereby promoting the reduction of Mn. 4+ Full reduction is achieved, which simultaneously promotes the transformation of the layered structure to a spinel structure, providing more lithium-ion insertion sites. Appropriate current settings within other voltage ranges are crucial to avoid material structural damage caused by improper current, such as suppressing the irreversible transformation from the spinel phase to the rock salt phase, thus maintaining material structural stability. Attached Figure Description

[0036] Figure 1 The first charge-discharge curves of the lithium-rich manganese-based batteries described in Example 1 and Comparative Example 1 of this invention are shown. Detailed Implementation

[0037] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0038] Example 1

[0039] This embodiment provides an activation method for a lithium-rich manganese-based battery, the activation method comprising the following steps:

[0040] (1) Lithium-rich manganese-based cathode material (Li 1.5 Ni 0.2 Co 0.1 Mn 0.7 O 2.5 Super carbon black and polyvinylidene fluoride were weighed in a mass ratio of 9:0.5:0.5 and mixed thoroughly to form a slurry. The slurry was then coated onto aluminum foil and vacuum dried at 100°C for 5 hours. After drying, the foil was placed on a roller press and cut into round sheets to obtain the positive electrode sheet.

[0041] The positive electrode was then assembled into a lithium-rich manganese-based battery. The lithium-rich manganese-based battery used a lithium metal sheet as the negative electrode, a polypropylene microporous membrane as the separator, and 1 mol / L LiPF6+EC (ethylene carbonate) / DMC (dimethyl carbonate) / EMC (ethyl methyl carbonate) as the electrolyte. The assembly of CR2430 stainless steel button cells was completed in a glove box filled with argon gas and with a moisture content of less than 0.1 ppm. The lithium-rich manganese-based battery was obtained and its charge-discharge performance was tested after standing for 12 hours.

[0042] (2) Place the lithium-rich manganese-based battery obtained in step (1) in a 50°C oven and let it stand for 20 hours.

[0043] (3) In the voltage range of 2.0-4.8V, constant current charging is performed at a charging current of 0.1C. When the voltage of the lithium-rich manganese-based battery reaches 4.8V, after standing for a period of time, constant current discharge is performed at a rate of 0.1C. When the voltage drops to 3.3V, the current density is reduced to a rate of 0.02C and constant current discharge is continued until 3.0V. After the voltage reaches 3.0V, the discharge current is restored to a rate of 0.1C and discharge is continued until the final cutoff voltage.

[0044] The initial charge-discharge curve of the lithium-rich manganese-based battery described in this embodiment is as follows: Figure 1 As shown.

[0045] Example 2

[0046] This embodiment provides an activation method for a lithium-rich manganese-based battery, the activation method comprising the following steps:

[0047] (1) Lithium-rich manganese-based cathode material (Li 1.5 Ni 0.17 Co 0.17 Mn 0.66 O 2.5 Super carbon black and polyvinylidene fluoride were weighed in a mass ratio of 9:0.5:0.5 and mixed thoroughly to form a slurry. The slurry was then coated onto aluminum foil and vacuum dried at 100°C for 5 hours. After drying, the foil was placed on a roller press and cut into round sheets to obtain the positive electrode sheet.

[0048] The positive electrode was then assembled into a lithium-rich manganese-based battery. The lithium-rich manganese-based battery used a lithium metal sheet as the negative electrode, a polypropylene microporous membrane as the separator, and 1 mol / L LiPF6+EC (ethylene carbonate) / DMC (dimethyl carbonate) / EMC (ethyl methyl carbonate) as the electrolyte. The assembly of CR2430 stainless steel button cells was completed in a glove box filled with argon gas and with a moisture content of less than 0.1 ppm. The lithium-rich manganese-based battery was obtained and its charge-discharge performance was tested after standing for 12 hours.

[0049] (2) Place the lithium-rich manganese-based battery obtained in step (1) in a 50°C oven and let it stand for 20 hours.

[0050] (3) In the voltage range of 2.0-4.8V, constant current charging is performed at a charging current of 0.1C. When the voltage of the lithium-rich manganese-based battery reaches 4.8V, after standing for a period of time, constant current discharge is performed at a rate of 0.1C. When the voltage drops to 3.3V, the current density is reduced to a rate of 0.02C and constant current discharge is continued until 3.0V. After the voltage reaches 3.0V, the discharge current is restored to a rate of 0.1C and discharge is continued until the final cutoff voltage.

[0051] Example 3

[0052] This embodiment provides an activation method for a lithium-rich manganese-based battery, the activation method comprising the following steps:

[0053] (1) Lithium-rich manganese-based cathode material (Li 1.5 Ni 0.2 Co 0.1 Mn 0.7 O 2.5 Super carbon black and polyvinylidene fluoride were weighed in a mass ratio of 9:0.5:0.5 and mixed thoroughly to form a slurry. The slurry was then coated onto aluminum foil and vacuum dried at 100°C for 5 hours. After drying, the foil was placed on a roller press and cut into round sheets to obtain the positive electrode sheet.

[0054] The positive electrode was then assembled into a lithium-rich manganese-based battery. The lithium-rich manganese-based battery used a lithium metal sheet as the negative electrode, a polypropylene microporous membrane as the separator, and 1 mol / L LiPF6+EC (ethylene carbonate) / DMC (dimethyl carbonate) / EMC (ethyl methyl carbonate) as the electrolyte. The assembly of CR2430 stainless steel button cells was completed in a glove box filled with argon gas and with a moisture content of less than 0.1 ppm. The lithium-rich manganese-based battery was obtained and its charge-discharge performance was tested after standing for 12 hours.

[0055] (2) Place the lithium-rich manganese-based battery obtained in step (1) in a 40°C oven and let it stand for 22 hours.

[0056] (3) In the voltage range of 2.0-4.8V, constant current charging is performed at a charging current of 0.3C. When the voltage of the lithium-rich manganese-based battery reaches 4.8V, after standing for a period of time, constant current discharge is performed at a rate of 0.3C. When the voltage drops to 3.3V, the current density is reduced to a rate of 0.005C and constant current discharge is continued until 3.0V. After the voltage reaches 3.0V, the discharge current is restored to a rate of 0.3C and discharge is continued until the final cutoff voltage.

[0057] Example 4

[0058] This embodiment provides an activation method for a lithium-rich manganese-based battery, the activation method comprising the following steps:

[0059] (1) Lithium-rich manganese-based cathode material (Li 1.5 Ni 0.2 Co 0.1 Mn 0.7 O 2.5 Super carbon black and polyvinylidene fluoride were weighed in a mass ratio of 9:0.5:0.5 and mixed thoroughly to form a slurry. The slurry was then coated onto aluminum foil and vacuum dried at 100°C for 5 hours. After drying, the foil was placed on a roller press and cut into round sheets to obtain the positive electrode sheet.

[0060] The positive electrode was then assembled into a lithium-rich manganese-based battery. The lithium-rich manganese-based battery used a lithium metal sheet as the negative electrode, a polypropylene microporous membrane as the separator, and 1 mol / L LiPF6+EC (ethylene carbonate) / DMC (dimethyl carbonate) / EMC (ethyl methyl carbonate) as the electrolyte. The assembly of CR2430 stainless steel button cells was completed in a glove box filled with argon gas and with a moisture content of less than 0.1 ppm. The lithium-rich manganese-based battery was obtained and its charge-discharge performance was tested after standing for 12 hours.

[0061] (2) Place the lithium-rich manganese-based battery obtained in step (1) in a 60°C oven and let it stand for 18 hours.

[0062] (3) In the voltage range of 2.0-4.8V, constant current charging is performed at a charging current of 0.5C. When the voltage of the lithium-rich manganese-based battery reaches 4.8V, after standing for a period of time, constant current discharge is performed at a rate of 0.5C. When the voltage drops to 3.3V, the current density is reduced to a rate of 0.1C and constant current discharge is continued until 3.0V. After the voltage reaches 3.0V, the discharge current is restored to a rate of 0.5C and discharge is continued until the final cutoff voltage.

[0063] Example 5

[0064] This embodiment provides an activation method for a lithium-rich manganese-based battery. The activation method is the same as in Embodiment 3, except that after the voltage drops to 3.3V, the current density is reduced to 0.2C and constant current discharge is continued until 3.0V.

[0065] Example 6

[0066] This embodiment provides an activation method for a lithium-rich manganese-based battery. The activation method is the same as in Embodiment 3, except that after the voltage drops to 3.3V, the current density is reduced to 0.001C and constant current discharge is continued until 3.0V.

[0067] Example 7

[0068] This embodiment provides an activation method for a lithium-rich manganese-based battery. The activation method is the same as in Embodiment 3, except that constant current discharge is performed at a rate of 0.1C, and when the voltage drops to 3.3V, the current density is reduced to a rate of 0.08C to continue constant current discharge to 3.0V; after the voltage reaches 3.0V, the discharge current is restored to a rate of 0.1C and discharge continues to the final cutoff voltage.

[0069] Comparative Example 1

[0070] This comparative example provides an activation method for a lithium-rich manganese-based battery, wherein the activation method, except that the lithium-rich manganese-based cathode material in step (1) is Li 1.5 Ni 0.25 Mn 0.75 O2.5 In step (3), constant current charging is performed at a charging current of 0.1C within a voltage range of 2.0-4.8V. When the voltage of the lithium-rich manganese-based battery reaches 4.8V, it is left to stand for a period of time and then constant current discharge is performed at a rate of 0.1C until the final cutoff voltage. The rest is the same as in Example 1.

[0071] The initial charge-discharge curve of the lithium-rich manganese-based battery described in this comparative example is as follows: Figure 1 As shown.

[0072] Comparative Example 2

[0073] This comparative example provides an activation method for a lithium-rich manganese-based battery. Except for step (3), which involves constant current charging at a charging current of 0.1C within a voltage range of 2.0-4.8V, and after the voltage of the lithium-rich manganese-based battery reaches 4.8V, it is left to stand for a period of time and then discharged at a constant current rate of 0.1C to the final cutoff voltage. The rest of the activation method is the same as in Example 1.

[0074] Comparative Example 3

[0075] This comparative example provides an activation method for a lithium-rich manganese-based battery. Except for step (3), which involves constant current charging at a charging current of 0.1C within a voltage range of 2.0-4.8V, and after the voltage of the lithium-rich manganese-based battery reaches 4.8V, allowing it to stand for a period of time before constant current discharge at a rate of 0.02C to the final cutoff voltage, the activation method is the same as in Example 1.

[0076] Comparative Example 4

[0077] This comparative example provides an activation method for a lithium-rich manganese-based battery. Except for step (3), which involves reducing the current density to 0.02C and continuing constant current discharge until the final cutoff voltage when the voltage drops to 3.0V, the activation method is the same as in Example 1.

[0078] The current density in different discharge ranges of the above embodiments and comparative examples is shown in Table 1; the initial discharge specific capacity and first efficiency (activation process) of the lithium-rich manganese-based batteries described in the above embodiments and comparative examples are also shown in Table 1. At the same time, the lithium-rich manganese-based batteries described in the above embodiments and comparative examples were subjected to cycle performance tests, and the capacity retention rate of 100 cycles at 0.5C was tested. The test results are also shown in Table 1.

[0079] Table 1

[0080]

[0081]

[0082] As can be seen from Table 1:

[0083] Examples 1-4 and Comparative Examples 1-2, combined with Figure 1 It is evident that when the current density during the discharge process remains constant, a relatively high current density is used for discharge, which fails to enable the lithium-rich manganese-based material to break through the capacity bottleneck of 300 mAh / g, and the battery's initial efficiency is low. Examples 1-4 and Comparative Example 3 show that when the current density during the discharge process remains constant, a relatively low current density is used for discharge. While this can improve the initial discharge specific capacity, it causes the material structure to collapse, leading to a decrease in the battery's cycle performance. Examples 1-4 and Comparative Example 4 show that maintaining a low current discharge below the 3.0V voltage range induces spinel-phase salt rock formation. Irreversible phase transitions ultimately lead to material failure. As shown in Examples 3 and 5, although the discharge current density was reduced in the 3.3V-3.0V range, the current density was still too high, resulting in limited improvement in the first discharge specific capacity. As shown in Examples 3 and 6, if the discharge current density in the 3.3V-3.0V range is reduced to too low, it will affect the material stability and thus the battery cycle performance. As shown in Examples 3 and 7, the preferred ratio of I2 / I1 in this invention is ≥1.5. When I2 and I1 are too close, it is not conducive to improving the discharge specific capacity.

[0084] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An activation method for a lithium-rich manganese-based battery, characterized in that, The activation method includes the following steps: The lithium-rich manganese-based battery is left to stand, then charged, and then discharged to the cutoff voltage to complete the activation. During the discharge process, the discharge is carried out using a current density of I1 when the voltage is in the range of 3.3V-3.0V, and the discharge is carried out using a current density of I2 when the voltage range is >3.3V and <3.0V, where I1 < I2.

2. The activation method according to claim 1, characterized in that, The I1 is below 0.1C, the I2 is above 0.1C, and I2 and I1 are not both at 0.1C; And / or, the I2 / I1 ≥ 1.

5.

3. The activation method according to claim 2, characterized in that, The discharge process includes: discharging the lithium-rich manganese-based battery at a current density of I2; when the voltage drops to 3.3V, reducing the current density to I1 to discharge to 3.0V; and then restoring the current density to I2 to continue discharging to the cutoff voltage. Where I1 is 0.005C-0.1C, I2 is 0.1C-0.5C, and I2 and I1 are not both 0.1C.

4. The activation method according to any one of claims 1-3, characterized in that, The charging and discharging voltage range is 2.0-4.8V.

5. The activation method according to any one of claims 1-3, characterized in that, The charging current density is 0.1C-0.5C.

6. The activation method according to any one of claims 1-3, characterized in that, After charging, the device is left to stand for a period of time before being discharged.

7. The activation method according to any one of claims 1-3, characterized in that, The temperature for allowing the lithium-rich manganese-based battery to stand is 40-60℃, and the time is 18-22 hours.

8. The activation method according to any one of claims 1-3, characterized in that, The lithium-rich manganese-based battery includes a positive electrode and a negative electrode, wherein the positive electrode includes a lithium-rich manganese-based positive electrode material with the general chemical formula Li. x Mn a Ni b Co c M d O 1+x Where 1 < x ≤ 2, 0.5 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0 < a + b + c + d ≤ 1, and M is selected from any one or at least two combinations of Co, Al, Mo, Mg, Fe, Nb, W, Zr, Ti or Cu; The negative electrode sheet includes a lithium metal sheet or a graphite negative electrode sheet.

9. A lithium-rich manganese-based battery, characterized in that, The lithium-rich manganese-based battery is obtained by activation using the activation method described in any one of claims 1-8.

10. An electronic device, characterized in that, The electronic device includes the lithium-rich manganese-based battery as described in claim 9.

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