A lithium-rich manganese-based lithium ion battery and an activation method and application thereof

Abstract

This invention provides a lithium-rich manganese-based lithium-ion battery, its activation method, and its applications. The activation method includes activating the lithium-rich manganese-based lithium-ion battery to obtain an activated lithium-rich manganese-based lithium-ion battery. The activation includes sequential constant-voltage charging and step charging. The single step amplitude U of the step charging is 0 < U ≤ 1V. The constant-voltage and step charging method used in this invention suppresses the release of active oxygen and controls the rearrangement of transition metal ions and lithium ions during the activation process. Different voltages and step amplitudes allow lithium ions to be extracted from the lithium-rich manganese-based structure in batches and to varying degrees, maintaining the structural integrity of the lithium-rich manganese-based material, thereby improving the battery's initial charge-discharge efficiency, discharge specific capacity, and cycle stability. Simultaneously, the activation method is simple, easy to operate, low-cost, and highly practical, significantly improving the battery's electrical performance and demonstrating excellent development prospects.

Description

Technical Field

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

[0002] Due to the development of 3C digital energy storage devices in recent years, the application of lithium-ion batteries has become increasingly widespread, and their market share has also increased. The trend of lithium-ion batteries is becoming more pronounced, and the development of new energy vehicles has entered a golden age. High energy density and low cost are the future development trends of lithium-ion batteries. The main cathode materials for lithium-ion batteries include lithium cobalt oxide (LCO) and nickel-cobalt-manganese ternary materials (NCM), with a maximum specific capacity of 200 mAh / g, leaving limited room for improvement. Furthermore, the materials are expensive, resources are limited, and there is little room for cost reduction. While lithium iron phosphate (LFP) and lithium manganese oxide (LMO) have significant cost advantages, their specific capacity is relatively low, making it difficult to improve the overall system energy density and meet the increasingly higher energy density requirements of the future.

[0003] The lithium-rich manganese-based cathode material (xLi2MnO3·(1-x)LiMO2, where 0≤x≤1 and M represents metal elements such as Ni and Co) has a specific capacity of over 250mAh / g. Moreover, this material is dominated by Mn, and the amount of other elements such as Ni and Co can be significantly reduced, which can minimize the cost of the material. At the same time, it is also one of the few cathode materials that can achieve 500Wh / kg in battery systems.

[0004] The high capacity of lithium-rich manganese-based batteries is partly due to the specific capacity provided by the rearranged Mn ions and O anions. Therefore, controlling the atomic arrangement after activation has a significant impact on the subsequent electrical performance of the material, because different rearranged structures vary considerably in the maintenance and stability of the layered structure during subsequent cycling. In other words, during the activation process of lithium-rich manganese-based materials, the rearrangement of transition metal ions has a huge impact on the subsequent electrochemical performance.

[0005] Mn in lithium-rich manganese-based materials 4+ Located in an octahedral crystal field, Mn 4+ The outer orbital electrons are arranged in a 1s... 2 2s 2 2p 6 3s 2 3p 6 3D 3 The three electrons in the outer d orbital occupy t2 in the octahedral field. g The orbital has very low energy, making it difficult for electrons to escape from t2. g The orbital derailment caused Mn to... 4+ It is difficult to be oxidized to Mn 5+However, charge transfer cannot be achieved in traditional electrochemical processes. Therefore, the activation method of lithium-rich manganese-based batteries is crucial for maximizing the performance of lithium-rich manganese-based materials.

[0006] Traditional activation methods for lithium-rich manganese-based batteries involve charging them to 4.6–4.8V using a constant current and constant voltage charging method. After activation, lithium ions are completely extracted from the lithium-rich manganese-based material structure, making transition metal ions more prone to migration, resulting in poor structural stability, continuous capacity decay, and a severe drop in discharge plateau voltage. CN104319422A discloses a method for improving the cycle stability of lithium-rich manganese lithium-ion batteries. This method includes a two-step activation treatment of the lithium-rich manganese lithium-ion battery after electrolyte injection at room temperature to fully utilize the performance of the lithium-rich manganese material. However, the structural reaction mechanism of lithium-rich manganese-based materials is still unclear, and there is no clear theory to explain the atomic rearrangement mechanism during the activation process of lithium-rich manganese-based materials.

[0007] Based on the above research, how to provide an activation method for lithium-rich manganese-based lithium-ion batteries that can control the release of active oxygen from lithium-rich manganese-based materials, optimize the activation and rearrangement process, and maintain the lithium-rich manganese-based materials as stable layered structures, thereby improving the initial efficiency, discharge specific capacity, and cycle performance of lithium-rich manganese-based lithium-ion batteries, has become an urgent problem to be solved. Summary of the Invention

[0008] The purpose of this invention is to provide a lithium-rich manganese-based lithium-ion battery, its activation method and application. The activation method can effectively suppress the release of active oxygen in the battery and control the rearrangement of transition metal ions and lithium ions during the activation process, thereby significantly improving the battery's first charge-discharge efficiency, discharge specific capacity and cycle stability.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, there is an activation method for a lithium-rich manganese-based lithium-ion battery, the activation method comprising: activating the lithium-rich manganese-based lithium-ion battery to obtain an activated lithium-rich manganese-based lithium-ion battery.

[0011] The activation includes sequential constant voltage charging and step charging;

[0012] The single step amplitude U of the step charging is 0 < U ≤ 1V, for example, it can be 0.01V, 0.1V, 0.2V, 0.3V, 0.4V, 0.5V, 0.6V, 0.7V, 0.8V, 0.9V or 1V, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0013] The step charging method employed in this invention enables a step change in voltage of the lithium-rich manganese-based lithium-ion battery, thereby controlling the sequence, manner, and speed of migration and extraction of transition metal ions, lithium ions, and oxygen atoms during the activation process. This step charging method provides the activation energy required for the extraction of lithium metal at different sites in the lithium-rich manganese-based lithium-ion battery, ensuring the extraction of different lithium ions at different voltages. By employing different step amplitudes, lithium ions can be extracted from the lithium-rich manganese-based structure in batches and to varying degrees, suppressing the release of activated oxygen and controlling the rearrangement process of metal ions. This maintains the structure of the lithium-rich manganese-based material during subsequent cycles, preserving its integrity and thus improving the battery's initial charge-discharge efficiency, discharge specific capacity, and cycle stability.

[0014] Preferably, the single step amplitude U is 0.01≤U≤0.5V, for example, it can be 0.01V, 0.1V, 0.2V, 0.3V, 0.4V or 0.5V, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 0.02≤U≤0.2V.

[0015] Preferably, the cutoff current of the step charging is KC, where K is 0 < K ≤ 0.3, for example, it can be 0.005, 0.01, 0.1, 0.2 or 0.3, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 0.005 ≤ K ≤ 0.1.

[0016] Preferably, the cutoff current of the constant voltage charging is K1C, where K1 is 0 < K1 ≤ 0.3, for example, it can be 0.005, 0.01, 0.1, 0.2 or 0.3, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 0.005 ≤ K1 ≤ 0.1.

[0017] Preferably, the total step amplitude of the step charge is 0.01 to 1V, for example, it can be 0.01V, 0.1V, 0.3V, 0.5V, 0.7V, 0.9V or 1V, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] Preferably, the constant voltage charging voltage is 4.40 to 4.55V, for example, it can be 4.40V, 4.45V, 4.50V or 4.55V, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, the activation further includes constant current discharge after step charging.

[0020] Preferably, the discharge current of the constant current discharge is 0.05 to 0.15C, for example, it can be 0.05C, 0.1C or 0.15C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] Preferably, the number of activations is N, where N≥1, for example, it can be 1, 2, 3, 4, 6, 7, 8, 9, 10 or 11 times, and N is preferably 1 to 2.

[0022] Preferably, the cutoff current of the (N+1)th activation is not lower than the cutoff current of the Nth activation.

[0023] Preferably, the cutoff current of the (N+1)th activation is 1 to 3 times the cutoff current of the Nth activation, for example, it can be 1, 2 or 3 times, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] The activation voltage range described in this invention can be adjusted according to different needs. When a high energy density battery is desired, the activation voltage range is wider, with an exemplary selectable floating range between ±0.5V; when a high cycle life battery is desired, the activation voltage range is narrower, with an exemplary selectable floating range between ±0.25V.

[0025] Preferably, the lithium-rich manganese-based lithium-ion battery includes a lithium-rich manganese-based cathode material, wherein the lithium-rich manganese-based cathode material is xLi2MnO3·(1-x)LiMeO2, where 0≤x≤1, and Me is a transition metal.

[0026] The lithium-rich manganese-based cathode material is xLi2MnO3·(1-x)LiMeO2, where 0≤x≤1, for example, it can be 0, 0.2, 0.4, 0.6, 0.8 or 1.0, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Preferably, Me includes any one or a combination of at least two of Ni, Co, Fe, Mn, Al, Mg or Ti. Typical but non-limiting combinations include combinations of Ni and Co, combinations of Ni and Fe, or combinations of Ni and Mn.

[0028] As a preferred embodiment of the activation method described in the first aspect of the present invention, the activation method includes the following steps:

[0029] An activated lithium-rich manganese-based lithium-ion battery is obtained by performing N activations on a lithium-rich manganese-based lithium-ion battery, where N≥1.

[0030] The activation includes the following steps:

[0031] (1) The lithium-rich manganese-based lithium-ion battery is charged at a constant voltage of 4.40 to 4.55V until the cutoff current is 0.005 to 0.1C;

[0032] (2) After constant voltage charging is completed, step charging is performed with a single step amplitude of 0.01 to 0.5V. The cutoff current of a single step charging is 0.005 to 0.1C; the total step amplitude of step charging is 0.01 to 1V.

[0033] (3) After the step charging is completed, the activation is completed by constant current discharge with a discharge current of 0.05 to 0.15C.

[0034] In a second aspect, the present invention provides an activated lithium-rich manganese-based lithium-ion battery, wherein the activated lithium-rich manganese-based lithium-ion battery is obtained by the activation method described in the first aspect.

[0035] Thirdly, the present invention provides an application of the activated lithium-rich manganese-based lithium-ion battery as described in the second aspect, the activated lithium-rich manganese-based lithium-ion battery being used in mobile phones, laptops, or electric vehicles.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] This invention utilizes a step-charging method to induce a step change in voltage in lithium-rich manganese-based lithium-ion batteries, thereby suppressing the release of reactive oxygen species and controlling the rearrangement of transition metal ions and lithium ions during the activation process. Different step amplitudes allow lithium ions to be extracted from the lithium-rich manganese-based structure in batches and to varying degrees, maintaining the structure and integrity of the material during subsequent cycles. This improves the battery's initial charge-discharge efficiency, discharge specific capacity, and cycle stability. The activation method provided by this invention enables lithium-rich manganese-based lithium-ion batteries to be used within a lower voltage range and suppresses the transformation of the lithium-rich manganese material to a spinel structure during cycling. Furthermore, the activation method is simple, easy to operate, low-cost, and highly practical, significantly improving the battery's electrical performance and demonstrating excellent development prospects. Attached Figure Description

[0038] Figure 1 These are the charge-discharge curves of the activation process of the lithium-rich manganese-based lithium-ion battery in Example 1 and the charge-discharge curves of the first cycle.

[0039] Figure 2 This is the differential curve of the first cycle after activation of the lithium-rich manganese-based lithium-ion battery in Example 1.

[0040] Figure 3 These are the charge-discharge curves of the activation process of the lithium-rich manganese-based lithium-ion battery in Example 4, and the charge-discharge curves of the first cycle.

[0041] Figure 4This is the differential curve of the first cycle after activation of the lithium-rich manganese-based lithium-ion battery in Example 4.

[0042] Figure 5 These are the charge-discharge curves of the activation process of the lithium-rich manganese-based lithium-ion battery in Example 7 and the charge-discharge curves of the first cycle.

[0043] Figure 6 This is the differential curve of the first cycle after activation of the lithium-rich manganese-based lithium-ion battery in Example 7.

[0044] Figure 7 These are the charge-discharge curves of the activation process of the lithium-rich manganese-based lithium-ion battery in Example 10 and the charge-discharge curves of the first cycle.

[0045] Figure 8 This is the differential curve of the first cycle after activation of the lithium-rich manganese-based lithium-ion battery in Example 10.

[0046] Figure 9 These are the charge-discharge curves of the activation process of the lithium-rich manganese-based lithium-ion battery in Example 11 and the charge-discharge curves of the first cycle.

[0047] Figure 10 This is the differential curve of the first cycle after activation of the lithium-rich manganese-based lithium-ion battery in Example 11.

[0048] Figure 11 These are the charge-discharge curves of the activation process of the lithium-rich manganese-based lithium-ion battery in Example 12 and the charge-discharge curves of the first cycle.

[0049] Figure 12 This is the differential curve of the first cycle after activation of the lithium-rich manganese-based lithium-ion battery in Example 12.

[0050] Figure 13 The figures show the charge-discharge curves of the activation process and the charge-discharge curves of the first cycle of the lithium-rich manganese-based lithium-ion battery in Comparative Example 1.

[0051] Figure 14 This is the differential curve of the first cycle after activation of the lithium-rich manganese-based lithium-ion battery in Comparative Example 1.

[0052] Figure 15 The figures show the charge-discharge curves of the activation process and the charge-discharge curves of the first cycle of the lithium-rich manganese-based lithium-ion battery in Comparative Example 2.

[0053] Figure 16 This is the differential curve of the first cycle after activation of the lithium-rich manganese-based lithium-ion battery in Comparative Example 2.

[0054] Figure 17 These are the charge-discharge curves of the activation process and the charge-discharge curves of the first cycle of the lithium-rich manganese-based lithium-ion battery in Comparative Example 3.

[0055] Figure 18This is the differential curve of the first cycle of the lithium-rich manganese-based lithium-ion battery after activation, as shown in Comparative Example 3. Detailed Implementation

[0056] 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.

[0057] The lithium-rich manganese-based lithium-ion batteries used in the following embodiments were prepared using the following method:

[0058] Lithium carbonate and nickel-manganese carbonate precursor (Ni) were mixed at a mass ratio of 23:50. 0.25 Mn 0.75 A mixture of CO3 and other gases was obtained; under an air atmosphere, the gas inlet rate was 1.5 L / min, and the temperature was increased from room temperature (20°C) to 500°C for 160 min, and the mixture was sintered for 5 hours. The temperature was then increased to 850°C at a rate of 3°C / min, and sintered for 16 hours. The mixture was then allowed to cool naturally to 25°C, and after sieving, lithium-rich manganese-based cathode material Li was obtained. 1.2 Ni 0.2 Mn 0.6 O2;

[0059] Li in a mass ratio of 18:1:1 1.2 Ni 0.2 Mn 0.6 O2, conductive carbon black, and polyvinylidene fluoride (HSV900) were mixed in N-methylpyrrolidone to obtain a slurry with a solid content of 50 wt%. The slurry was coated onto an aluminum foil with a thickness of 20 μm and a coating gap of 200 μm. After drying at 120°C for 30 min, the resulting powder thickness was approximately 30 μm. The powder was then rolled and compacted to a density of 2.2 g / cm³. 3 Lithium-rich manganese-based positive electrode sheet was obtained;

[0060] The lithium-rich manganese-based positive electrode, a 500μm thick lithium metal negative electrode, a glass microfiber filter paper GF / D (whatman) separator, and a high-voltage electrolyte (Shandong Hairong Power Materials Co., Ltd., model 8825) are assembled into a button cell in a glove box to obtain the lithium-rich manganese-based lithium-ion battery.

[0061] Example 1

[0062] This embodiment provides an activation method for a lithium-rich manganese-based lithium-ion battery, the activation method comprising:

[0063] (1) The lithium-rich manganese-based lithium-ion battery is charged at a constant voltage of 4.40V until the cutoff current is 0.01C.

[0064] (2) After constant voltage charging is completed, step charging is performed with a single step amplitude of 0.01V until the cutoff current is 0.01C and the cutoff voltage is 4.6V.

[0065] (3) After constant voltage charging and step charging are completed, constant current discharge is carried out at 0.1C to 2.5V to complete one activation;

[0066] The activation process and the charge-discharge curve for the first cycle are as follows: Figure 1 As shown, the differential curve for the first cycle after activation is as follows: Figure 2 As shown.

[0067] Example 2

[0068] This embodiment provides an activation method for a lithium-rich manganese-based lithium-ion battery, the activation method comprising:

[0069] (1) The lithium-rich manganese-based lithium-ion battery is charged at a constant voltage of 4.40V until the cutoff current is 0.005C.

[0070] (2) After constant voltage charging is completed, step charging is performed with a single step amplitude of 0.05V until the cutoff current is 0.1C and the cutoff voltage is 4.6V.

[0071] (3) After the constant voltage charging and step charging are completed, the constant current discharge is carried out at a discharge current of 0.05C to 2.5V to complete one activation.

[0072] Example 3

[0073] This embodiment provides an activation method for a lithium-rich manganese-based lithium-ion battery, the activation method comprising:

[0074] (1) The lithium-rich manganese-based lithium-ion battery is charged at a constant voltage of 4.40V until the cutoff current is 0.1C;

[0075] (2) After constant voltage charging is completed, step charging is performed with a single step amplitude of 0.1V until the cutoff current is 0.005C and the cutoff voltage is 4.6V.

[0076] (3) After the constant voltage charging and step charging are completed, the constant current discharge is carried out at a discharge current of 0.15C to 2.5V to complete one activation.

[0077] Example 4

[0078] This embodiment provides an activation method for a lithium-rich manganese-based lithium-ion battery. The activation method is the same as that in Embodiment 1, except that the single step amplitude is 0.02V.

[0079] The activation process and the charge-discharge curve for the first cycle are as follows: Figure 3As shown, the differential curve for the first cycle after activation is as follows: Figure 4 As shown.

[0080] Example 5

[0081] This embodiment provides an activation method for a lithium-rich manganese-based lithium-ion battery. The activation method is the same as that in Embodiment 1, except that the single step amplitude is 0.03V.

[0082] Example 6

[0083] This embodiment provides an activation method for a lithium-rich manganese-based lithium-ion battery. The activation method is the same as that in Embodiment 1, except that the single step amplitude is 0.05V.

[0084] Example 7

[0085] This embodiment provides an activation method for a lithium-rich manganese-based lithium-ion battery. The activation method is the same as in Embodiment 1, except that the cutoff voltage for step charging is 4.55V.

[0086] The activation process and the charge-discharge curve for the first cycle are as follows: Figure 5 As shown, the differential curve for the first cycle after activation is as follows: Figure 6 As shown.

[0087] Example 8

[0088] This embodiment provides an activation method for a lithium-rich manganese-based lithium-ion battery. Except for the step charging cutoff voltage of 4.50V, the activation method is the same as that in Embodiment 1.

[0089] Example 9

[0090] This embodiment provides an activation method for a lithium-rich manganese-based lithium-ion battery. Except for the step charging cutoff voltage of 4.45V, the activation method is the same as that in Embodiment 1.

[0091] Example 10

[0092] This embodiment provides an activation method for a lithium-rich manganese-based lithium-ion battery. The activation method is the same as in Embodiment 1, except that the constant voltage charging voltage is 4.45V.

[0093] The activation process and the charge-discharge curve for the first cycle are as follows: Figure 7 As shown, the differential curve for the first cycle after activation is as follows: Figure 8 As shown.

[0094] Example 11

[0095] This embodiment provides an activation method for a lithium-rich manganese-based lithium-ion battery. The activation method is the same as in Embodiment 1, except that the constant voltage charging voltage is 4.5V.

[0096] The activation process and the charge-discharge curve for the first cycle are as follows: Figure 9 As shown, the differential curve for the first cycle after activation is as follows: Figure 10 As shown.

[0097] Example 12

[0098] This embodiment provides an activation method for a lithium-rich manganese-based lithium-ion battery. The activation method is the same as in Embodiment 1, except that the constant voltage charging voltage is 4.55V.

[0099] The activation process and the discharge curve of the first charge cycle are as follows: Figure 11 As shown, the differential curve for the first cycle after activation is as follows: Figure 12 As shown.

[0100] Example 13

[0101] This embodiment provides an activation method for a lithium-rich manganese-based lithium-ion battery, the activation method comprising two activation steps;

[0102] The first activation method of the two activations is the same as that in Example 1;

[0103] The second activation method for the two activations is the same as in Example 1, except that the cutoff current for both constant voltage charging and step charging is 0.02C.

[0104] Example 14

[0105] This embodiment provides an activation method for a lithium-rich manganese-based lithium-ion battery, the activation method comprising three activation steps;

[0106] The first activation method of the three activations is the same as that in Example 1;

[0107] The second activation method of the three-stage activation is the same as that in Example 1, except that the cutoff current for both constant voltage charging and step charging is 0.02C.

[0108] The third activation method of the three activations is the same as that in Example 1, except that the cutoff current for both constant voltage charging and step charging is 0.04C.

[0109] Comparative Example 1

[0110] This comparative example provides an activation method for a lithium-rich manganese-based lithium-ion battery, the activation method comprising:

[0111] (1) The lithium-rich manganese-based lithium-ion battery is charged at a constant current of 0.1C until the cutoff voltage is 4.55V.

[0112] (2) Charge at a constant voltage of 4.55V until the cutoff current is 0.01C to complete the charging process;

[0113] (3) After charging is complete, discharge at a constant current of 0.1C to 2.5V to complete one activation;

[0114] The activation process and the charge-discharge curve for the first cycle are as follows: Figure 13 As shown, the differential curve for the first cycle after activation is as follows: Figure 14 As shown.

[0115] Comparative Example 2

[0116] This comparative example provides an activation method for a lithium-rich manganese-based lithium-ion battery, the activation method comprising:

[0117] (1) The lithium-rich manganese-based lithium-ion battery was charged at a constant current of 0.1C until the cutoff voltage was 4.6V;

[0118] (2) Then charge at a constant voltage of 4.6V until the cutoff current is 0.01C to complete the charging;

[0119] (3) After charging is complete, discharge at a constant current of 0.1C to 2.5V to complete one activation;

[0120] The activation process and the charge-discharge curve for the first cycle are as follows: Figure 15 As shown, the differential curve for the first cycle after activation is as follows: Figure 16 As shown.

[0121] Comparative Example 3

[0122] This comparative example provides an activation method for a lithium-rich manganese-based lithium-ion battery, the activation method comprising:

[0123] (1) The lithium-rich manganese-based lithium-ion battery is charged at a constant current of 0.1C until the cutoff voltage is 4.7V;

[0124] (2) Charge at a constant voltage of 4.7V until the cutoff current is 0.01C to complete the charging process;

[0125] (3) After charging is completed, discharge at a constant current of 0.1C to 2.5V to complete one activation.

[0126] The activation process and the charge-discharge curve for the first cycle are as follows: Figure 17 As shown, the differential curve for the first cycle after activation is as follows: Figure 18 As shown.

[0127] The activated lithium-rich manganese-based lithium-ion batteries provided in the above embodiments and comparative examples were charged at a constant current and constant voltage of 0.33C to a voltage of 4.6V and a current of 0.033C, rested for 2 minutes, discharged at 0.5C to 2.5V, and after 50 cycles, their 50-cycle retention rate was tested.

[0128] The test results are shown in Table 1:

[0129] Table 1

[0130]

[0131]

[0132] The following points can be observed from Table 1:

[0133] (1) As can be seen from Examples 1 and 4, the single step amplitude in Example 1 is 0.01V, and the single step amplitude in Example 4 is 0.02V. According to the activation method provided in Example 1, from Figure 2 It can be seen that there are three bun-shaped oxidation peaks in the 3.5–4.2V range, and the latter two peaks are not obvious. According to the activation method provided in Example 4, from Figure 4 It can be seen that the oxidation peak ratio in the range of 3.5 to 4.2 V is... Figure 2 The oxidation process is significantly enhanced at a potential of 3.75V, indicating that the metal elements have undergone different rearrangements.

[0134] (2) As can be seen from Examples 4 to 6, when the step voltage is increased from 0.02V to 0.05V, the charging specific capacity gradually increases, the activated portion of Li2MnO3 increases, the irreversible discharge specific capacity increases significantly, the first charge and discharge efficiency decreases, and after the step voltage is increased, the discharge specific capacity after activation and rearrangement also decreases accordingly.

[0135] (3) As can be seen from Examples 1 and 7, the cutoff voltage for step charging in Example 1 is 4.6V, and the cutoff voltage for step charging in Example 7 is 4.55V. According to the activation method provided in Example 7, from Figure 6 It can be seen that the peak ratio of the oxidation peak is significantly weakened in the range of 3.5 to 4.2V, and the reduction peak at around 3.1V is also significantly weakened. Therefore, the contribution of Example 7 to the discharge capacity is significantly smaller than that of Example 1.

[0136] (4) As can be seen from Examples 7 to 9, when the charging cutoff voltage decreases continuously, the activated part of Li2MnO3 gradually decreases, the charging specific capacity decreases continuously, Li and Mn do not migrate out of the main structure of the material, the irreversible capacity decreases continuously, the first charge and discharge efficiency increases continuously, and when the cutoff voltage decreases to 4.45V, the metallic lithium of the negative electrode lithium sheet can also be partially reversibly charged into the structure of the lithium-rich manganese-based material.

[0137] (5) As can be seen from Examples 1 and 10, the constant voltage charging voltage in Example 1 is 4.40V, and the constant voltage charging voltage in Example 10 is 4.45V. According to the activation method provided in Example 10, from Figure 8 It can be seen that there are only two obvious oxidation peaks in the range of 3.5 to 4.2 V, and the oxidation peak near 3.8 V is significantly broadened, indicating that different metal oxidation processes have occurred, which in turn has a significant impact on the subsequent capacity performance.

[0138] (6) As can be seen from Examples 1 and 11, the constant voltage charging voltage in Example 1 is 4.40V, and the constant voltage charging voltage in Example 10 is 4.5V. According to the activation method provided in Example 11, from Figure 10 It can be seen that there are three indistinct oxidation peaks in the range of 3.5 to 4.2 V, and the reduction peak near 3.1 V is weakened, indicating that the metal elements have undergone different rearrangements.

[0139] (7) As can be seen from Examples 1 and 12, the constant voltage charging voltage in Example 1 is 4.40V, and the constant voltage charging voltage in Example 10 is 4.55V. According to the activation method provided in Example 12, from Figure 12 It can be seen that three distinct oxidation peaks appear in the range of 3.5–4.2 V, and the oxidation peak near 3.8 V is significantly enhanced. Ni 2+ Its contribution to the oxidation process has increased significantly.

[0140] (8) As can be seen from Examples 1 and 10-12, by controlling different constant voltage charging voltages, the lithium removal method is changed to a certain extent, reducing Mn. 4+ O3 4- The reduced content of intermediate states decreases the oxygen content generated in subsequent chemical steps, thereby improving the stability of the layered structure of manganese-rich lithium-based materials and significantly increasing the initial efficiency of manganese-rich lithium-ion batteries.

[0141] (9) As can be seen from Examples 10 to 12, the voltage of constant voltage charging increases sequentially while the cutoff voltage remains unchanged. The order of Li extraction in the Li2MnO3 component is adjusted, and some of them will be extracted synchronously with the lithium ions in the ternary part, which will have a certain impact on the rearrangement of the discharge process, and the cycle retention rate gradually decreases.

[0142] (10) As can be seen from Examples 1 and 13-14, as the number of activations increases, the discharge specific capacity and cycle stability of the material first increase and then decrease. Initially, the material was not fully activated and rearranged. After three activations, the Li2MnO3 structure of the material was more fully activated, and the cycle stability of the material deteriorated.

[0143] (11) As can be seen from Example 1 and Comparative Example 1, according to the activation method provided in Comparative Example 1, from Figure 14 It can be seen that the three oxidation peaks appearing in the 3.5–4.2 V range are not obvious, exhibiting broadening; as shown in Example 1 and Comparative Example 2, according to the activation method provided in Comparative Example 2, from Figure 16 It can be seen that there are only two oxidation peaks in the range of 3.5 to 4.2 V, and the oxidation peaks near 3.9 V disappear significantly; as can be seen from Example 1 and Comparative Example 3, according to the activation method provided in Comparative Example 3, from Figure 18 It can be seen that three obvious oxidation peaks appear in the range of 3.5 to 4.2V, and one obvious oxidation peak appears near 3.2V, which is the oxidation peak of layered Mn. This indicates that after activation, the contribution of Mn to the capacity is significantly enhanced, but the electrical performance of the manganese-rich lithium-ion battery provided by it is still significantly reduced compared with Example 1.

[0144] In summary, this invention provides a lithium-rich manganese-based lithium-ion battery, its activation method, and its application. The activation method includes: activating the lithium-rich manganese-based lithium-ion battery to obtain an activated lithium-rich manganese-based lithium-ion battery; the activation includes sequential constant voltage charging and step charging; the single step amplitude U of the step charging is 0 < U ≤ 1V. The step charging method employed in this invention causes a step change in the voltage of the lithium-rich manganese-based lithium-ion battery, thereby suppressing the release of reactive oxygen species and controlling the rearrangement of transition metal ions and lithium ions during the activation process. Different step amplitudes allow lithium ions to be extracted from the lithium-rich manganese-based structure in batches and to varying degrees, maintaining the structure and integrity of the lithium-rich manganese-based material during subsequent cycles, thus improving the battery's initial charge-discharge efficiency, discharge specific capacity, and cycle stability. The activation method provided by this invention enables the use of lithium-rich manganese-based lithium-ion batteries within a lower voltage range and can suppress the transformation of the lithium-rich manganese material to a spinel structure during cycling. Furthermore, the activation method is simple, easy to operate, low-cost, and highly practical, significantly improving the battery's electrical performance and demonstrating excellent development prospects.

[0145] 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. A method of activation of a lithium-rich manganese-based lithium-ion battery, characterized in that, The activation method comprises: activating the lithium-rich manganese-based lithium ion battery to obtain an activated lithium-rich manganese-based lithium ion battery. The activation comprises constant voltage charging and step charging performed in sequence. The single step amplitude U of the step charging is 0 The voltage of the constant voltage charging is 4.40-4.55 V.

2. The activation method of claim 1, wherein, The single step amplitude U is 0.01 3. The method of activation of claim 2, wherein, The single step amplitude U is 0.02 4. The activation method of claim 1, wherein, The cutoff current of the step charging is KC, and the K is 0 5. The activation method of claim 4, wherein, The K is 0.005 6. The activation method of claim 1, wherein, The total step amplitude of the step charging is 0.01-1 V.

7. The activation method of claim 1, wherein, The cutoff current of the constant voltage charging is K1C, and the K1 is 0 8. The activation method of claim 7, wherein, The K1 is 0.005 9. The activation method of claim 1, wherein, The activation further comprises constant current discharging after the step charging.

10. The activation method of claim 9, wherein, The discharging current of the constant current discharging is 0.05-0.15 C.

11. The activation method of claim 1, wherein, The number of activations is N, and N is greater than or equal to 1.

12. The activation method of claim 11, wherein, The N is 1-2.

13. The activation method of claim 11, wherein, The cutoff current of the N+1th activation is not lower than the cutoff current of the Nth activation.

14. The activation method of claim 1, wherein, The lithium-rich manganese-based lithium ion battery comprises a lithium-rich manganese-based positive electrode material, and the lithium-rich manganese-based positive electrode material is xLi2MnO3·(1-x)LiMeO2, wherein 0 15. The activation method of claim 14, wherein, The Me comprises any one or a combination of at least two of Ni, Co, Fe, Mn, Al, Mg or Ti.

16. The method of activation of claim 1 wherein, The activation method comprises the following steps: The lithium-rich manganese-based lithium ion battery is activated for N times, and N is greater than or equal to 1, to obtain an activated lithium-rich manganese-based lithium ion battery. The activation comprises the following steps: (1) The lithium-rich manganese-based lithium ion battery is charged at a voltage of 4.40-4.55 V to a cutoff current of 0.005-0.1 C by constant voltage charging; (2) After the constant voltage charging, step charging is performed at a single step amplitude of 0.01-0.5 V, and the cutoff current of the single step charging is 0.005-0.1 C; The total step amplitude of the step charging is 0.01-1 V; (3) After the step charging, constant current discharging is performed at a discharging current of 0.05-0.15 C, and one activation is completed.

17. An activated lithium-rich manganese-based lithium-ion battery, characterized in that, The activated lithium-rich manganese-based lithium ion battery is obtained by using the activation method according to any one of claims 1-16.

18. Use of an activated lithium-rich manganese-based lithium-ion battery as claimed in claim 17, characterized in that, The activated lithium-rich manganese-based lithium ion battery is used for mobile phones, notebook computers or electric vehicles.

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