Electrochemically induced solvent participation regulated lithium-rich manganese-based positive electrode material and method

Abstract

The application provides a lithium-rich manganese-based positive electrode material and a method for electrochemically inducing a solvent to participate in regulation, which comprises mixing a lithium-rich manganese-based layered oxide positive electrode material, a conductive agent and a binder according to a predetermined ratio, preparing a uniform slurry and coating the slurry on the surface of an aluminum foil current collector, and obtaining a positive electrode sheet after drying and rolling; assembling the positive electrode sheet, a negative electrode and a separator into an electrochemical cell; injecting an electrolyte containing at least one functional solvent into the electrochemical cell; and performing first or previous several times of charge-discharge treatment on the electrochemical cell, so that the functional solvent participates in the initial structure evolution regulation of the positive electrode material during high-potential charge-discharge process, thereby improving the electrochemical stability of the lithium-rich manganese-based positive electrode material in the subsequent cycle process without changing the material bulk composition. The method is simple in process and strong in repeatability, and is suitable for the field of lithium ion batteries.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery cathode material technology, and more specifically, it relates to a lithium-rich manganese-based cathode material and method with electrochemically induced solvent participation in regulation. Background Technology

[0002] Lithium-rich manganese-based layered oxide cathode materials possess the electrochemical characteristics of both transition metal redox reactions and lattice oxygen participation, resulting in high theoretical specific capacity and energy density, making them important candidate cathode materials for realizing high-energy-density lithium-ion batteries. However, in practical applications, these materials still suffer from problems such as large irreversible capacity loss during the first charge-discharge cycle, significant voltage decay, and insufficient cycle stability, which severely restrict their large-scale application.

[0003] To address the aforementioned issues, existing technologies typically modify lithium-rich manganese-based cathode materials through elemental doping, surface coating, structural design, or morphology control. However, these methods generally suffer from drawbacks such as complex processes, high preparation costs, and limited applicability to material systems. Furthermore, they often focus on controlling the static structure of the material, paying insufficient attention to the dynamic structural evolution behavior of the material during the first or initial high-potential charge-discharge cycles.

[0004] Studies have found that lithium-rich manganese-based cathode materials undergo significant structural rearrangement and local environmental changes during the first or initial charge-discharge cycles, a process that has a crucial impact on their subsequent cycle performance. However, in existing battery systems, the electrolyte typically serves only as a lithium-ion transport medium, and its potential regulatory role in the initial electrochemical activation stage of the material has not been fully explored. Therefore, how to effectively regulate the structural evolution behavior of lithium-rich manganese-based cathode materials during the initial charge-discharge stage through electrochemical means without altering the bulk material composition remains a pressing technical problem to be solved in this field. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an electrochemically induced solvent-mediated regulation of lithium-rich manganese-based cathode material and method, thereby solving the technical problem that in the prior art, traditional lithium-rich manganese-based cathode materials undergo significant structural rearrangement and local environmental changes during the first or first few charge-discharge cycles, which affects the electrochemical stability of the lithium-rich manganese-based cathode material in subsequent cycles.

[0006] The purpose and effectiveness of this invention, which describes an electrochemically induced solvent-mediated controlled lithium-rich manganese-based cathode material and method, are achieved through the following specific technical means: An electrochemical treatment method for lithium-rich manganese-based cathode materials with electrochemically induced solvent participation and regulation includes the following steps: S1: Obtain lithium-rich manganese-based layered oxide cathode material; S2: Mix lithium-rich manganese-based layered oxide cathode material, conductive agent and binder in a predetermined ratio to prepare a uniform slurry and coat it on the surface of aluminum foil current collector. After drying and rolling, a cathode sheet is obtained. S3: An electrochemical cell is assembled using a positive electrode, a negative electrode, and a separator. S4: Injecting an electrolyte containing at least one functional solvent into an electrochemical cell; S5: Perform the first or first few charge-discharge treatments on the electrochemical battery to allow the functional solvent to participate in the electrochemical regulation of the layered structure of lithium-rich manganese-based base oxides during the charge-discharge process, thereby improving the electrochemical stability of the cathode material in subsequent cycles.

[0007] In a preferred embodiment, in step S1, the chemical formula of the lithium-rich manganese-based layered oxide is: Where 0.1≤x≤0.3, and M is one or more of Ni, Co, Al, Fe, Cr, Ti, Zr, and Mo.

[0008] In a preferred embodiment, in step S2, the mass ratio of the lithium-rich manganese-based layered oxide cathode material, the conductive agent, and the binder is (70-90):(5-15):(5-15).

[0009] In a preferred embodiment, the positive electrode sheet is prepared by mixing the components to prepare a uniform slurry, coating it onto the surface of an aluminum foil current collector, vacuum drying it at 80-120℃ for 8-16 hours, and then rolling it to obtain the positive electrode sheet. The areal density of the active material in the positive electrode sheet is 1.5-3.0 mg / cm³. 2 .

[0010] In a preferred embodiment, in step S3, the electrochemical battery is assembled into a CR2032 coin cell using a lithium metal anode and a polypropylene separator.

[0011] In a preferred embodiment, in step S4, the functional solvent is selected from one or more of ether solvents, carbonate solvents, sulfonamide solvents, and fluorinated solvents, and the volume fraction of the functional solvent in the electrolyte is 5%-50%.

[0012] In a preferred embodiment, the electrolyte further includes a lithium salt and a base solvent, wherein the lithium salt is selected from one or more of LiPF6, LiFSI, LiTFSI, and LiDFOB, and the lithium salt concentration is 0.8-1.5 mol / L; the base solvent is selected from one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

[0013] In a preferred embodiment, in step S5, the cutoff voltage for the first or several charging processes is 4.5-4.9V, and the charging and discharging processes are performed using a constant current or a combination of constant current and constant voltage; when using the combination of constant current and constant voltage, the constant voltage holding time is 10-60 minutes.

[0014] In a preferred embodiment, the current density of the charge-discharge process is 0.05-0.2C, the charge-discharge process is carried out at room temperature or under elevated temperature conditions of 20-60°C, and the first few charge-discharge processes are 1-5 cycles.

[0015] A lithium-rich manganese-based cathode material with electrochemically induced solvent participation regulation, wherein the lithium-rich manganese-based cathode material is obtained by the above-mentioned electrochemical treatment method, and the lithium-rich manganese-based cathode material is used as a cathode active material in lithium-ion batteries.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention induces functional solvents to participate in the initial regulation of the lithium-rich manganese-based matrix structure through electrochemical means, eliminating the need for additional modification of the lithium-rich manganese-based cathode material. Existing technologies for modifying lithium-rich manganese-based cathode materials often involve elemental doping and surface coating, requiring additional process steps during material synthesis, increasing the complexity of the preparation process and production costs. The regulation process of this invention is carried out in the electrochemical treatment stage after battery assembly, without changing the original material synthesis process. It is compatible with existing lithium-ion battery production processes, with simple process steps, strong operability, and can reduce the technical threshold and cost input in the production process, making it suitable for large-scale production applications.

[0017] 2. The regulation process mainly occurs during the first or initial charge-discharge cycles of the battery. It can guide the structural evolution of lithium-rich manganese-based cathode materials in the early stages of their service life, forming a more stable and controllable electrochemical evolution path. During the first charge-discharge cycle, lithium-rich manganese-based cathode materials undergo significant structural rearrangement and local environmental changes. Traditional processes lack effective regulation of this process, easily leading to irreversible structural defects and phase transitions, which can cause performance degradation in subsequent cycles. This invention, through the participation of functional solvents in the high-potential charge-discharge process, can directionally guide the structural rearrangement in the initial stage of the material, suppressing unfavorable structural evolution and enabling the material to form a more stable crystal structure and interface state, thereby improving electrochemical stability.

[0018] 3. The lithium-rich manganese-based cathode material treated by the method of this invention exhibits more stable electrochemical performance during subsequent cycling. Through initial electrochemical regulation, the bulk structure and surface interface state of the lithium-rich manganese-based cathode material are optimized, reducing problems such as lattice distortion, transition metal ion dissolution, and interfacial side reactions caused by structural instability during cycling. This enables the battery to maintain stable capacity retention performance during long-term charge-discharge cycles, mitigate voltage decay during charge-discharge, maintain good charge-discharge characteristics, and improve the overall cycle life and reliability of the battery. Attached Figure Description

[0019] Figure 1 This is a comparison curve of the cycle performance of Example 1 and Comparative Example 1 in this invention; Figure 2 This is a voltage-capacity curve of Comparative Example 1 in the first and second charge-discharge cycles of the present invention; Figure 3 This is a voltage-capacity curve diagram of Embodiment 1 of the present invention during the first and second charge-discharge cycles. Figure 4 This is a flowchart of the steps of an electrochemical treatment method for lithium-rich manganese-based cathode materials regulated by an electrochemically induced solvent, according to the present invention. Detailed Implementation

[0020] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the technical solutions of the present invention, but should not be used to limit the scope of protection of the present invention.

[0021] Example 1:

[0022] As attached Figures 1 to 4 As shown: This invention provides an electrochemical treatment method for lithium-rich manganese-based cathode materials with electrochemically induced solvent regulation, characterized by comprising the following steps: S1: Obtain lithium-rich manganese-based basal oxide cathode material.

[0023] In this embodiment, the chemical formula of the lithium-rich manganese-based layered oxide is: Where 0.1≤x≤0.3, M is one or more of Ni, Co, Al, Fe, Cr, Ti, Zr, and Mo. The material corresponding to this chemical formula possesses dual electrochemical characteristics of transition metal redox and lattice oxygen redox, which can provide a high theoretical specific capacity for lithium-ion batteries. In the formula, x represents the excess lithium content in the material. This range of excess lithium can provide additional charge-discharge capacity to the battery while maintaining the basic stability of the material's layered structure. Manganese, as the core transition metal element in the material, participates in the redox reaction during charge-discharge, contributing significantly to the capacity. M represents other transition metals or metallic elements; different combinations of elements can... It can adjust the electronic structure and crystal field environment of the material, optimize the charge and discharge voltage platform and structural stability of the material. Among them, nickel and cobalt can improve the discharge voltage and specific capacity of the material, while aluminum, iron, chromium, titanium, zirconium, molybdenum and other elements can enhance the rigidity of the crystal structure of the material and suppress the structural collapse during cycling. The lithium-rich manganese base layer oxide in this composition range can adapt to the subsequent electrochemical regulation process, ensuring that the functional solvent can effectively participate in the structural evolution regulation of the material during charge and discharge. The material can be prepared by conventional cathode material synthesis methods such as solid-state method, co-precipitation method, sol-gel method, etc. After synthesis, the material is ground and sieved to obtain powder with uniform particle size.

[0024] S2: Mix lithium-rich manganese-based morphological oxide cathode material, conductive agent and binder in a predetermined ratio to prepare a uniform slurry and coat it on the surface of aluminum foil current collector. After drying and rolling, a cathode sheet is obtained.

[0025] In this embodiment, the mass ratio of lithium-rich manganese-based layered oxide cathode material, conductive agent, and binder is (70-90):(5-15):(5-15). This mass ratio range can balance the specific capacity, conductivity, and mechanical strength of the cathode sheet. The lithium-rich manganese-based layered oxide serves as the cathode active material, and its mass proportion ensures that the electrode has sufficient electrochemical active sites to provide adequate charge and discharge capacity for the battery. The conductive agent is used to construct continuous electron transport channels between active material particles and between the active material and the current collector, reducing the internal resistance of the electrode. The binder is used to bond the active material particles and the conductive agent together, and to firmly attach the electrode to the surface of the aluminum foil current collector, preventing the active material from falling off during subsequent processing and cycling. The preparation process of the cathode sheet is as follows: the components are mixed to prepare a uniform slurry, which is then coated onto the surface of the aluminum foil current collector. After vacuum drying at 80-120℃ for 8-16 hours, the cathode sheet is obtained by rolling. The areal density of the active material in the cathode sheet is 1.5-3.0 mg / cm³. 2The mixing process ensures uniform dispersion of components within the system, preventing localized unevenness and guaranteeing consistent electrochemical performance across all areas of the electrode. The coating process evenly distributes the slurry onto the surface of the aluminum foil current collector, forming a uniformly thick active material layer. The vacuum drying process removes organic solvents from the slurry, preventing residual solvents from adversely affecting battery performance. This temperature and time range ensures complete solvent evaporation while preventing the electrode from cracking or the active material from deteriorating due to excessively high temperatures or prolonged drying times. The rolling process increases the compaction density of the electrode, expands the contact area between active material particles, further reduces the internal resistance of the electrode, and improves its mechanical strength. The range of active material areal density balances the battery's energy density and rate performance, preventing excessively high areal density from causing excessively long lithium-ion transport paths or excessively low areal density from causing insufficient battery energy density.

[0026] Specifically, lithium-rich manganese-based layered oxides Li were selected. 1.2 Mn 0.6 Ni 0.2 O2, used as the positive electrode active material, possesses high theoretical specific capacity and operating voltage, providing high energy density for the battery. This material, along with SuperP conductive carbon black and polyvinylidene fluoride (PVDF), is mixed in a mass ratio of 80:10:10. SuperP conductive carbon black has a high specific surface area and good conductivity, forming an effective conductive network even with low addition amounts. PVDF exhibits good bonding properties and chemical stability, maintaining stable bonding in the electrolyte environment. N-methylpyrrolidone is added to prepare a slurry, which is continuously stirred until it becomes uniform and free of particles. This slurry is then uniformly coated onto the surface of an aluminum foil current collector. The aluminum foil, as the positive electrode current collector, possesses good conductivity and chemical stability, collecting electrons generated by the positive electrode and transferring them to the external circuit. After vacuum drying at 100℃ for 12 hours, the material is rolled. This drying condition effectively removes the N-methylpyrrolidone solvent while ensuring the structural integrity of the electrode. The areal density of the positive electrode active material is controlled at 2.0-2.5 mg / cm³. 2 This areal density enables the electrode to possess both good energy density and charge / discharge performance.

[0027] S3: An electrochemical battery is assembled using a positive electrode, a negative electrode, and a separator.

[0028] In this embodiment, the electrochemical battery is assembled into a CR2032 coin cell using a lithium metal anode and a polypropylene separator. The lithium metal anode has a high theoretical specific capacity and a low redox potential, which can be matched with lithium-rich manganese-based cathode materials to form a high-voltage battery system. Furthermore, using lithium metal as the anode in laboratory tests eliminates the interference of anode performance on the electrochemical performance test results of the cathode material, accurately reflecting the intrinsic performance of the electrochemically regulated lithium-rich manganese-based cathode material. The polypropylene separator has good chemical stability and mechanical strength, maintaining structural stability in the electrolyte environment. Its porous structure can adsorb and retain the electrolyte, providing a continuous channel for lithium-ion transport. Simultaneously, it physically separates the cathode and anode plates, preventing direct contact and internal short circuits, thus ensuring battery safety. The CR2032 coin cell is a commonly used battery packaging form in laboratories. It features simple assembly process, low cost, and good test repeatability. It is suitable for electrochemical performance testing and regulation effect verification of lithium-rich manganese-based cathode materials. The assembly process is carried out in an argon-filled glove box with water and oxygen content of less than 0.5 ppm. The negative electrode shell, lithium metal negative electrode sheet, polypropylene separator, positive electrode sheet, stainless steel gasket, stainless steel spring sheet, and positive electrode shell are stacked in sequence, so that the active material side of the positive electrode sheet and the active side of the lithium metal negative electrode sheet are respectively facing the two sides of the polypropylene separator. The coin cell sealing machine is used to seal the battery to complete the assembly. The assembled battery has good sealing performance, which can prevent external moisture and oxygen from entering the battery and avoid electrolyte deterioration and electrode material oxidation.

[0029] S4: Inject an electrolyte containing at least one functional solvent into the electrochemical cell.

[0030] In this embodiment, the functional solvent is selected from one or more of ether solvents, carbonate solvents, sulfonamide solvents, and fluorinated solvents. Different types of functional solvents have different molecular structures and electrochemical properties, and can participate in the structural evolution regulation of lithium-rich manganese-based layered oxides through different mechanisms during high-potential charging and discharging. The volume fraction of the functional solvent in the electrolyte is 5%-50%. This volume fraction range ensures that there are sufficient functional solvent molecules in the electrolyte to participate in the regulation process, while avoiding the adverse effects of an excessively high proportion of functional solvent on the basic physicochemical properties and ion transport performance of the electrolyte. The electrolyte also includes a lithium salt and a base solvent. The lithium salt is selected from one or more of LiPF6, LiFSI, LiTFSI, and LiDFOB. The lithium salt is used in the... The electrolyte dissociates to generate migratable lithium ions, providing charge carriers for the battery's charging and discharging process. The lithium salt concentration is 0.8-1.5 mol / L. This concentration range ensures that the electrolyte has a sufficient lithium ion concentration to meet the charge transport requirements during charging and discharging, while avoiding problems such as excessively high electrolyte viscosity and decreased lithium ion migration rate due to excessively high lithium salt concentration, or insufficient electrolyte conductivity due to excessively low concentration. The base solvent is selected from one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. The base solvent is used to dissolve the lithium salt and functional solvent, and to adjust the electrolyte's viscosity, dielectric constant, and liquid temperature range. Mixing multiple base solvents in different proportions can synergistically optimize the overall performance of the electrolyte, enabling the electrolyte to simultaneously meet the requirements of ionic conductivity, chemical stability, and electrochemical stability.

[0031] Specifically, the electrolyte is prepared by dissolving 1.0 mol / L LiPF6 in a mixed solvent of ethylene carbonate and dimethyl carbonate in a 1:1 volume ratio, with 20% functional solvent added. Ethyl carbonate has a high dielectric constant, which can effectively promote the dissociation of lithium salts and participate in the formation of the interfacial film on the electrode surface. Dimethyl carbonate has a low viscosity, which can reduce the overall viscosity of the electrolyte and improve the migration rate of lithium ions. The 1:1 volume ratio of the two solvents balances the dielectric constant and viscosity of the electrolyte, resulting in a suitable ionic conductivity. LiPF6, as a commonly used lithium salt, has moderate ionic conductivity and interfacial film-forming ability, enabling it to form a stable interfacial layer on the electrode surface. The addition of 20% functional solvent ensures that it fully participates in the structural regulation of lithium-rich manganese-based basal oxides during charge and discharge, while maintaining the basic electrochemical performance of the electrolyte. The electrolyte preparation process is carried out in an argon-filled glove box with water and oxygen content of less than 0.5 ppm. The lithium salt is slowly added to the base solvent and stirred until completely dissolved. Then, the functional solvent is added and stirred evenly to obtain a clear and transparent electrolyte. The prepared electrolyte is sealed and stored in an argon-filled glove box to avoid deterioration due to contact with moisture and oxygen. A certain amount of electrolyte is injected into the assembled electrochemical battery to fully wet all the pores of the positive electrode, separator and negative electrode, ensuring the continuity of the lithium-ion transport channel.

[0032] S5: Perform the first or first few charge-discharge treatments on the electrochemical battery to allow the functional solvent to participate in the electrochemical regulation of the layered structure of lithium-rich manganese-based base oxides during the charge-discharge process, thereby improving the electrochemical stability of the cathode material in subsequent cycles.

[0033] In this embodiment, the cutoff voltage for the first or initial charging cycles is 4.5-4.9V. This voltage range is sufficient to fully activate the lithium-rich phase component in the lithium-rich manganese-based basal oxide, triggering the initial structural rearrangement process of the material. Simultaneously, it provides sufficient electrochemical driving force for the functional solvent, enabling it to interact with the surface and near-surface of the cathode material at high potentials and participate in structural regulation. Too low a voltage will not effectively activate the lithium-rich phase and will also make it difficult to induce the functional solvent to play a regulatory role. Too high a voltage will lead to excessive decomposition of the electrolyte, generating a large number of byproducts and affecting battery performance. The charge / discharge process employs constant current or constant current-- The constant-voltage and constant-current charging / discharging methods are combined. Constant-current charging and discharging ensure that the battery reacts at a stable current density, allowing the lithium-ion insertion and extraction processes to proceed uniformly. The combination of constant-current and constant-voltage allows the active materials inside the battery to fully participate in the reaction after the constant-current charging reaches the cutoff voltage, ensuring the uniformity and sufficiency of the structural regulation process. When using this method, the constant-voltage holding time is 10-60 minutes. This time range ensures that the battery completes a full charging process while allowing sufficient time for the functional solvent to interact with the cathode material, achieving effective structural regulation. The charge-discharge treatment current density is 0.05-0.2C. Using a lower current density allows lithium ions to diffuse sufficiently within the cathode material, ensuring uniform structural rearrangement within the material. It also allows sufficient time for the functional solvent to diffuse to the surface and near-surface regions of the cathode material, enabling adequate interaction. Excessive current density leads to an overly rapid reaction rate, insufficient lithium ion diffusion, and inadequate uniform participation of the functional solvent in structural regulation, thus affecting the regulation effect. The charge-discharge treatment is conducted at room temperature (20-60℃) or under elevated temperatures. Appropriate temperatures can enhance the ionization of the electrolyte. Conductivity and reaction kinetics rate promote the interaction between functional solvents and cathode materials, improving the efficiency and effect of structure regulation. Excessive temperature will accelerate the decomposition of electrolyte and the occurrence of side reactions, while excessively low temperature will lead to slow ion transport rate and difficulty in fully carrying out the reaction. The first few charge-discharge cycles are 1-5 cycles. The initial structural rearrangement of lithium-rich manganese-based basal oxides mainly occurs in the first and first few charge-discharge processes. Regulation at this stage can guide the material structure evolution in the early stage and form a stable structural basis. Too many charge-discharge cycles will increase the processing time and cannot further improve the regulation effect.

[0034] Specifically, the battery was initially charged at 25°C with a charging current density of 0.1C and a charging cutoff voltage of 4.8V. This voltage was maintained at a constant level for 30 minutes. Subsequently, the battery was discharged to 2.0V at the same current density. 25°C represents standard room temperature conditions, requiring no additional heating or cooling equipment. The operation is simple and easy to control. The low current density of 0.1C ensures sufficient diffusion of lithium ions in the cathode material, allowing for uniform structural rearrangement. The 4.8V charging cutoff voltage effectively activates the lithium-rich phase in the lithium-rich manganese-based material, while providing suitable electrochemical driving force for the functional solvent, enabling its participation in structural regulation. The 30-minute constant voltage holding time ensures a complete charging process, allowing all active sites to participate in the reaction and facilitating sufficient interaction between the functional solvent and the cathode material. Discharging to 2.0V at the same current density completes a full charge-discharge cycle, ensuring the initial structural rearrangement of the material is fully realized, resulting in a stable initial structure. After completing the above electrochemical induction treatment, the battery was subjected to cycle performance testing at 0.5C. The cycle performance test was used to evaluate the electrochemical stability of the electrochemically regulated lithium-rich manganese-based cathode material during subsequent long-term charge-discharge processes, and to verify the actual effect of the regulation method. Through the participation of functional solvents in the high-potential charge-discharge process, the initial structural rearrangement of the material can be directionally guided, and unfavorable structural evolution can be suppressed, so that the material forms a more stable crystal structure and interface state. It can guide the structural evolution behavior of the lithium-rich manganese-based cathode material in the early stage of service, forming a more stable and controllable electrochemical behavior evolution path. It can reduce problems such as lattice distortion, dissolution of transition metal ions and interface side reactions caused by structural instability during cycling, improve the electrochemical stability of the lithium-rich manganese-based cathode material in subsequent cycles, enable the battery to maintain stable capacity retention performance during long-term charge-discharge processes, alleviate voltage decay during charge-discharge processes, and maintain good charge-discharge characteristics.

[0035] A lithium-rich manganese-based cathode material with electrochemically induced solvent participation regulation, wherein the lithium-rich manganese-based cathode material is obtained by the above-mentioned electrochemical treatment method, and the lithium-rich manganese-based cathode material is used as a cathode active material in lithium-ion batteries.

[0036] Comparative Example 1: Except that the electrolyte system does not contain the aforementioned functional solvents, the other material composition, battery assembly method, and electrochemical testing conditions are the same as in Example 1.

[0037] Test results are as follows Figure 1 As shown, compared with Comparative Example 1, Example 1 exhibits more stable capacity retention behavior during cycling. Figure 2 and Figure 3The voltage-capacity curves of Comparative Example 1 and Example 1 during the first and second charge-discharge cycles are shown respectively. It can be seen that the lithium-rich manganese-based cathode material treated by the electrochemical treatment method of the present invention exhibits different electrochemical behavior evolution characteristics in the initial charge-discharge stage, and shows better stability in subsequent cycles.

[0038] It should be noted that, without departing from the technical concept of this invention, the specific types of functional solvents and their volume fraction in the electrolyte, the charge / discharge current density during electrochemical treatment, the initial charge cutoff voltage, the constant voltage holding time, and the number of treatment cycles in the embodiments can all be reasonably adjusted according to the specific composition of the lithium-rich manganese-based cathode material, the battery structure, and testing requirements. For example, the volume fraction of the functional solvent can vary within the range of 5%-50%, the initial charge cutoff voltage can be selected within the range of 4.5-4.9V, and the first few charge / discharge treatments can be 1-5 cycles. Adjustments to the above parameters can achieve the technical effect of inducing the functional solvent to participate in the initial structural evolution regulation of the lithium-rich manganese-based cathode material through electrochemical means, and should all fall within the protection scope of this invention.

Claims

1. An electrochemical treatment method for lithium-rich manganese-based cathode materials with electrochemically induced solvent participation regulation, characterized in that: It includes the following steps: S1: Obtain lithium-rich manganese-based layered oxide cathode material; S2: Mix lithium-rich manganese-based layered oxide cathode material, conductive agent and binder in a predetermined ratio to prepare a uniform slurry and coat it on the surface of aluminum foil current collector. After drying and rolling, a cathode sheet is obtained. S3: An electrochemical cell is assembled using a positive electrode, a negative electrode, and a separator. S4: Inject an electrolyte containing at least one functional solvent into an electrochemical cell; S5: Perform the first or first few charge-discharge treatments on the electrochemical battery to allow the functional solvent to participate in the electrochemical regulation of the layered structure of lithium-rich manganese-based base oxides during the charge-discharge process, thereby improving the electrochemical stability of the cathode material in subsequent cycles.

2. The electrochemical treatment method for lithium-rich manganese-based cathode materials with electrochemically induced solvent-mediated regulation according to claim 1, characterized in that: In step S1, the chemical formula of the lithium-rich manganese-based layered oxide is: Where 0.1≤x≤0.3, and M is one or more of Ni, Co, Al, Fe, Cr, Ti, Zr, and Mo.

3. The electrochemical treatment method for lithium-rich manganese-based cathode materials with electrochemically induced solvent-mediated regulation according to claim 1, characterized in that: In step S2, the mass ratio of the lithium-rich manganese-based layered oxide cathode material, the conductive agent, and the binder is (70-90):(5-15):(5-15).

4. The electrochemical treatment method for lithium-rich manganese-based cathode materials with electrochemically induced solvent participation regulation according to claim 3, characterized in that: The preparation process of the positive electrode sheet is as follows: the components are mixed to prepare a uniform slurry, which is then coated onto the surface of an aluminum foil current collector. After vacuum drying at 80-120℃ for 8-16 hours, the positive electrode sheet is obtained by rolling. The areal density of the active material in the positive electrode sheet is 1.5-3.0 mg / cm³. 2 .

5. The electrochemical treatment method for lithium-rich manganese-based cathode materials with electrochemically induced solvent-mediated regulation according to claim 1, characterized in that: In step S3, the electrochemical cell is assembled into a CR2032 coin cell using a lithium metal anode and a polypropylene separator.

6. The electrochemical treatment method for lithium-rich manganese-based cathode materials with electrochemically induced solvent-mediated regulation according to claim 1, characterized in that: In step S4, the functional solvent is selected from one or more of ether solvents, carbonate solvents, sulfonamide solvents, and fluorinated solvents, and the volume fraction of the functional solvent in the electrolyte is 5%-50%.

7. The electrochemical treatment method for lithium-rich manganese-based cathode materials with electrochemically induced solvent-mediated regulation according to claim 6, characterized in that: The electrolyte also includes a lithium salt and a base solvent. The lithium salt is selected from one or more of LiPF6, LiFSI, LiTFSI, and LiDFOB, and the lithium salt concentration is 0.8-1.5 mol / L. The base solvent is selected from one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

8. The electrochemical treatment method for lithium-rich manganese-based cathode materials with electrochemically induced solvent-mediated regulation according to claim 1, characterized in that: In step S5, the cutoff voltage for the first or several charging processes is 4.5-4.9V, and the charging and discharging processes are performed using constant current or a combination of constant current and constant voltage. When using the combination of constant current and constant voltage, the constant voltage holding time is 10-60 minutes.

9. The electrochemical treatment method for lithium-rich manganese-based cathode materials with electrochemically induced solvent participation regulation according to claim 8, characterized in that: The current density of the charge-discharge process is 0.05-0.2C, and the charge-discharge process is carried out at room temperature or under elevated temperature conditions of 20-60℃. The first few charge-discharge processes consist of 1-5 cycles.

10. A lithium-rich manganese-based cathode material with electrochemically induced solvent-mediated regulation, characterized in that: The lithium-rich manganese-based cathode material is obtained by the electrochemical treatment method described in any one of claims 1-9, and the lithium-rich manganese-based cathode material is used as a cathode active material in lithium-ion batteries.

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