Method for in-situ modification of electrode material by negative thermal expansion material
By modifying electrode materials in situ with negative thermal expansion materials, the problem of structural collapse of lithium-rich manganese-based cathode materials during charging and discharging was solved, improving electrochemical performance and safety, and achieving enhanced material stability and safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-05
- Publication Date
- 2026-03-31
AI Technical Summary
During the charging and discharging process, lithium-rich manganese-based cathode materials suffer structural collapse due to oxygen evolution, resulting in a decline in electrochemical performance. Furthermore, they react with the electrolyte to generate Li2O, which inhibits Li+ transport and affects battery performance and safety.
The method of in-situ modification of electrode materials using negative thermal expansion materials involves adding negative thermal expansion materials or their precursors during the synthesis of electrode materials. This utilizes the thermal expansion properties of the materials to absorb heat and reduce internal stress, thereby improving interfacial contact and suppressing oxygen evolution and side reactions.
It significantly improves the specific capacity and cycle stability of electrode materials, enhances electrochemical performance, and reduces structural deformation and safety risks.
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Figure CN121769029A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of energy materials technology, specifically to an in-situ modification method for improving the electrochemical performance and safety of electrode materials. Background Technology
[0002] Lithium-ion batteries possess advantages such as high energy density, high coulombic efficiency, strong self-charging capability, and long cycle life, and have been widely used in portable electronic products, electric vehicles, hybrid vehicles, and stationary energy storage. Lithium-rich manganese-based cathode materials (LRMO) are particularly valuable due to their high specific capacity (>300 mAh g⁻¹). -1 With its high operating voltage (2.0-4.8V) and low cost, LRMO has become one of the most promising cathode materials for lithium-ion batteries. However, LRMO still faces many challenges, such as low coulombic efficiency in the first cycle, poor rate performance, and severe voltage decay. Therefore, research on modifications to address these problems is of great significance.
[0003] The key scientific challenge in lithium-rich manganese-based cathode materials is currently suppressing the release of surface and bulk oxygen. During charge and discharge, irreversible oxygen release from the crystal lattice forms micropores within the material, accelerating the structural transformation from layered to spinel phase, ultimately leading to structural collapse and a sharp decline in electrochemical performance. The released oxygen can also react with free Li in the electrolyte. + The reaction produces Li₂O, which not only reduces the amount of reversible Li₂O produced. + Furthermore, the accumulation of Li₂O on the electrode surface further inhibits Li₂O₃ deposition. + The transmission of oxygen is a crucial process. To address these challenges, common modification methods include ion doping, surface modification, single-crystal structure design, and surface treatment. These modification techniques affect materials by suppressing lattice oxygen loss, improving electronic and ionic conductivity, inhibiting electrolyte corrosion, and suppressing structural phase transitions. Surface modification is an extremely effective method, suppressing oxygen evolution during charge and discharge, improving material structural stability, and inhibiting side reactions at the interface with the electrolyte.
[0004] The concept of this invention is to modify electrode materials in situ with negative thermal expansion materials. By improving the interface and suppressing the electrochemical performance decay caused by side reactions during cycling, the invention utilizes the properties of negative thermal expansion materials to absorb heat in situ and reduce deformation hazards, thereby alleviating stress accumulation and reducing internal stress, thus improving the specific capacity and cycling stability of the electrode materials. Summary of the Invention
[0005] Based on the technical problems existing in the background technology, the present invention proposes a method for in-situ modification of electrode materials with negative thermal expansion materials, with the aim of improving the electrochemical performance and safety of electrode materials.
[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A negative thermal expansion material or its precursor is added during the synthesis of electrode materials, and the electrode material modified in situ by calcination is obtained.
[0007] The negative thermal expansion material refers to a material that shrinks in volume when heated, and the negative thermal expansion material precursor refers to the substance that is synthesized before the target product, the negative thermal expansion material, is synthesized.
[0008] The electrode materials mentioned refer to positive electrode materials and negative electrode materials.
[0009] A method for in-situ modification of electrode materials using negative thermal expansion materials, characterized by comprising the following steps: Step 1: According to the molar ratio, dissolve the different raw materials required for the electrode material in deionized water to obtain a mixed metal salt solution; Step 2: Add precipitant solution and complexing agent solution to the metal salt solution obtained in Step 1 to carry out a co-precipitation reaction to obtain the electrode material precursor; Step 3: The electrode material precursor and lithium salt from Step 2 are mixed in stoichiometric ratio and then calcined in an oxygen atmosphere to obtain the electrode material. Step 4: Mix the electrode material from Step 3 with the negative thermal expansion precursor powder in a certain mass ratio, and then calcine to obtain the electrode material modified in situ by the negative thermal expansion material.
[0010] In step one, the different raw materials required for the electrode material are any one or a combination of oxides, hydroxides, sulfates, acetates, nitrates, and chlorides of the corresponding raw materials.
[0011] In step two, the precipitant solution includes a sodium hydroxide solution or a sodium carbonate solution.
[0012] In step two, the complexing agent solution includes one of ammonia, ethylenediaminetetraacetic acid, or sodium citrate solution.
[0013] In step three, the lithium salt includes any one or a combination of lithium hydroxide, lithium carbonate, lithium oxalate, lithium phosphate, lithium dihydrogen phosphate, and lithium hydrogen phosphate.
[0014] In step three, the calcination is first performed by heating the temperature to 300-500℃ for pre-calcination, and then by heating the temperature to 500-900℃ for calcination.
[0015] In step four, the mass ratio of the negative thermal expansion material precursor powder to the electrode material is (0.01~20):100).
[0016] The method provided by this invention utilizes materials with negative thermal expansion characteristics to modify electrode materials in situ, improving the interface between the electrode material and the negative thermal expansion material, reducing interfacial resistance, and suppressing the electrochemical performance decay caused by side reactions during cycling. In addition, the thermal shrinkage characteristics can alleviate stress accumulation and reduce deformation, absorb heat during electrode cycling to reduce volume, eliminate or reduce internal stress and volume expansion during cycling, eliminate or reduce adverse effects such as performance degradation and safety accidents caused by deformation and heat, and thus significantly improve the electrochemical performance of the electrode material, which is conducive to large-scale promotion and application. Attached Figure Description
[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 A schematic diagram of an in-situ modified electrode material with negative thermal expansion characteristics.
[0019] Figure 2 This is a scanning electron microscope (SEM) image of the final product prepared in Example 1.
[0020] Figure 3 The image shows the EDS spectrum of the final product prepared in Example 1.
[0021] Figure 4 The XRD diffraction patterns are those of the cobalt-free lithium-rich manganese-based cathode materials prepared in Examples 1, 2, 3 and Comparative Example 1.
[0022] Figure 5 The first charge-discharge curves of the cobalt-free lithium-rich manganese-based cathode materials prepared in Examples 1, 2, 3 and Comparative Example 1 are shown.
[0023] Figure 6 The graph shows a comparison of the rate performance of the cobalt-free lithium-rich manganese-based cathode materials prepared in Examples 1, 2, 3 and Comparative Example 1. Detailed Implementation
[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0025] The material characterization and analysis instruments and methods used in the following examples and comparative examples are as follows: Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS): Using a scanning electron microscope (SEM) model JSM-7500F, manufactured by Nippon Electron, the microstructure and elemental distribution of the material surface were observed. X-ray diffraction (XRD) test: Using an X-ray diffractometer, model X'Pert Pro MPD DY129, Panaco Corporation, to analyze the phase structure of the material; Electrochemical cycle test: The electrochemical performance of the material was tested using a charge-discharge tester, model BTS-3000, manufactured by Xinwei Electronics.
[0026] Assembly and testing of CR2025 button batteries: The positive electrode material (the final product obtained in the example), acetylene black, and polyvinylidene fluoride (PVDF) were prepared into a slurry in a mass ratio of 8:1:1 and coated onto aluminum foil. The dried aluminum foil loaded with the slurry was cut into small circular pieces with a diameter of 1.4 cm using a cutting machine to be used as the positive electrode. Lithium metal sheet was used as the negative electrode, Celgard2500 was used as the separator, and 5V high-voltage carbonate electrolyte was used. The CR2025 button batteries were assembled in an argon atmosphere glove box. Example
[0027] This embodiment provides a method for in-situ modification of a cobalt-free lithium-rich manganese-based cathode material with the negative thermal expansion material ZrW2O8, thereby improving its electrochemical performance and safety. The cobalt-free lithium-rich manganese-based cathode material is a ZrW2O8-modified Li... 1.2 Mn 0.6 Ni 0.2 The O2 cathode material is prepared using the following steps: Dissolving NiSO4·6H2O and MnSO4·H2O in deionized water yields 2 mol L -1 50 ml of a transition metal salt solution. NaOH dissolved in deionized water yields 4 mol / L. -1 Prepare 50 ml of a 2 mol / L alkaline solution. - 1 Na₂SO₄ solution was poured into a round-bottom flask, and then heated to 55°C in a water bath for later use. The two solutions were then pumped at 5 mL / min using a peristaltic pump. -1 The solution was simultaneously pumped into a three-necked flask at a rate that allowed for the addition of a 0.5 mol L solution. -1 Ammonia was used as a complexing agent, and the mixture was continuously stirred. The entire process was carried out in an N2 environment with a stirring speed of 800 r / min and a pH maintained at 12. After feeding, the mixture was stirred continuously for 8 hours and aged for 5 hours. Then, it was filtered, washed, and dried at 60℃ for 12 hours to obtain the precursor Mn. 0.75 Ni0.25 (OH)₂. Subsequently, the precursor was thoroughly ground with an excess of 5% LiOH·H₂O in a mortar, and sintered at 500℃ and 900℃ for 5 h and 12 h under O₂ atmosphere, respectively, to obtain cobalt-free lithium-rich manganese-based cathode materials. ZrW₂O₈ precursor powder was synthesized by hydrothermal method, and 12 ml of 0.25 mol / L solution was used. -1 Zr(C2H3O2)4 and 12 ml of it have a concentration of 0.50 mol L. -1 Na₂WO₄·2H₂O were added dropwise to 12 ml of solution, resulting in a concentration of 7 mol / L. -1 The ZrW2O8 precursor powder was obtained by stirring thoroughly in an HCl solution at 130°C for 12 hours, followed by centrifugation and drying. The cobalt-free lithium-rich manganese-based cathode material was then thoroughly mixed with the ZrW2O8 precursor powder at a mass ratio of 100:5, and calcined at 600°C for 3 hours in air to obtain the in-situ modified ZrW2O8 cobalt-free lithium-rich manganese-based cathode material. Figure 1 The image shows a scanning electron microscope (SEM) image of the cobalt-free lithium-rich manganese-based cathode material prepared in Example 1. As can be seen from the image, the sample has a relatively uniform particle size and good density, and is composed of fibrous spherical particles. Figure 2 The image shows the EDS spectrum of the final product prepared in Example 1. It can be seen from the image that zirconium and tungsten elements are uniformly distributed on the surface of the cobalt-free lithium-rich manganese-based cathode material. Example
[0028] This embodiment provides a method for improving the electrochemical performance and safety of cobalt-free lithium-rich manganese-based cathode materials, wherein the cobalt-free lithium-rich manganese-based cathode material is ZrW2O8 in-situ modified Li. 1.2 Mn 0.6 Ni 0.2 The O2 cathode material is prepared using the following steps: Dissolving NiSO4·6H2O and MnSO4·H2O in deionized water yields 2 mol L -1 50 ml of a transition metal salt solution. NaOH dissolved in deionized water yields 4 mol / L. -1 Prepare 50 ml of a 2 mol / L alkaline solution. - 1 Na₂SO₄ solution was poured into a round-bottom flask, and then heated to 55°C in a water bath for later use. The two solutions were then pumped at 5 mL / min using a peristaltic pump. -1 The solution was simultaneously pumped into a three-necked flask at a rate that allowed for the addition of a 0.5 mol L solution. -1Ammonia was used as a complexing agent, and the mixture was continuously stirred. The entire process was carried out in an N2 environment with a stirring speed of 800 r / min and a pH maintained at 12. After feeding, the mixture was stirred continuously for 8 hours and aged for 5 hours. Then, it was filtered, washed, and dried at 60℃ for 12 hours to obtain the precursor Mn. 0.75 Ni 0.25 (OH)₂. Subsequently, the precursor was thoroughly ground with an excess of 5% LiOH·H₂O in a mortar, and sintered at 500℃ and 900℃ for 5 h and 12 h under O₂ atmosphere, respectively, to obtain cobalt-free lithium-rich manganese-based cathode materials. ZrW₂O₈ precursor powder was synthesized by hydrothermal method, and 12 ml of 0.25 mol / L solution was used. -1 Zr(C2H3O2)4 and 12 ml of it have a concentration of 0.50 mol L. -1 Na₂WO₄·2H₂O were added dropwise to 12 ml of solution, resulting in a concentration of 7 mol / L. -1 The ZrW2O8 precursor powder was obtained by stirring thoroughly in an HCl solution at 130°C for 12 hours, followed by centrifugation and drying. The cobalt-free lithium-rich manganese-based cathode material was then thoroughly mixed with the ZrW2O8 precursor powder at a mass ratio of 100:3, and calcined at 600°C for 3 hours in air to obtain the in-situ modified ZrW2O8 cobalt-free lithium-rich manganese-based cathode material. Example
[0029] This embodiment provides a method for improving the electrochemical performance and safety of cobalt-free lithium-rich manganese-based cathode materials, wherein the cobalt-free lithium-rich manganese-based cathode material is ZrW2O8 in-situ modified Li. 1.2 Mn 0.6 Ni 0.2 The O2 cathode material is prepared using the following steps: Dissolving NiSO4·6H2O and MnSO4·H2O in deionized water yields 2 mol L -1 50 ml of a transition metal salt solution. NaOH dissolved in deionized water yields 4 mol / L. -1 Prepare 50 ml of a 2 mol / L alkaline solution. - 1 Na₂SO₄ solution was poured into a round-bottom flask, and then heated to 55°C in a water bath for later use. The two solutions were then pumped at 5 mL / min using a peristaltic pump. -1 The solution was simultaneously pumped into a three-necked flask at a rate that allowed for the addition of a 0.5 mol L solution. -1 Ammonia was used as a complexing agent, and the mixture was continuously stirred. The entire process was carried out in an N2 environment with a stirring speed of 800 r / min and a pH maintained at 12. After feeding, the mixture was stirred continuously for 8 hours and aged for 5 hours. Then, it was filtered, washed, and dried at 60℃ for 12 hours to obtain the precursor Mn.0.75 Ni 0.25 (OH)₂. Subsequently, the precursor was thoroughly ground with an excess of 5% LiOH·H₂O in a mortar, and sintered at 500℃ and 900℃ for 5 h and 12 h under O₂ atmosphere, respectively, to obtain cobalt-free lithium-rich manganese-based cathode materials. ZrW₂O₈ precursor powder was synthesized by hydrothermal method, and 12 ml of 0.25 mol / L solution was used. -1 Zr(C2H3O2)4 and 12 ml of it have a concentration of 0.50 mol L. -1 Na₂WO₄·2H₂O were added dropwise to 12 ml of solution, resulting in a concentration of 7 mol / L. -1 The ZrW2O8 precursor powder was obtained by stirring thoroughly in an HCl solution at 130°C for 12 hours, followed by centrifugation and drying. The cobalt-free lithium-rich manganese-based cathode material was then thoroughly mixed with the ZrW2O8 precursor powder at a mass ratio of 100:7, and calcined at 600°C for 3 hours in air to obtain the in-situ modified ZrW2O8 cobalt-free lithium-rich manganese-based cathode material. Example
[0030] This embodiment provides a method for improving the electrochemical performance and safety of high-nickel ternary cathode materials, wherein the high-nickel ternary cathode material is Cu2V2O7 in-situ modified Li. 1.0 Ni 0.9 2Co 0.03 Mn 0.05 The O2 cathode material is prepared using the following steps: NiSO4·6H2O, CoSO4·7H2O and MnSO4·H2O were prepared according to Ni 2+ :Co 2+ :Mn 2 A mixture of Ni and Ni with a molar ratio of 9.2:0.3:0.5 was dissolved in deionized water to form a 2 mol / L solution. Subsequently, under nitrogen protection, the mixed solution was added to the precursor synthesis reactor at a uniform rate. Simultaneously, a certain amount of 2 mol / L NaOH solution was added to the reactor as a precipitant, and an appropriate amount of 20 wt% NH3·H2O was added as a complexing agent. During the reaction, the pH value in the reactor was strictly controlled at 10.5 ± 0.1, and the temperature was kept constant at 50 °C to ensure sufficient reaction time. After co-precipitation, the precursor was filtered and washed with deionized water, then vacuum dried at 85 °C for 24 hours to obtain the precursor Ni. 0.92 Co 0.03 Mn 0.05(OH)2. Subsequently, the precursor was thoroughly ground with an excess of 5% LiOH·H2O in a mortar, then pre-calcined at 500℃ for 5 hours, followed by calcination at 700℃ for 15 hours under a continuous oxygen flow to obtain a high-nickel ternary cathode material. The synthesis of the negative thermal expansion material Cu2V2O7 involved dissolving white solid powder NH4VO3 in pure water at 80℃ and heating and stirring thoroughly until the white solid powder was not completely dissolved. Then, a dissolved CuSO4 solution was added, and NH3·H2O was added to the system to adjust the pH to alkaline. After the reaction was complete, a yellow-green precipitate (Cu3V2O7(OH)2·nH2O) was prepared; then it was filtered, washed, and dried at 80℃ for 12 hours to obtain the Cu2V2O7 precursor. The high-nickel ternary cathode material was thoroughly mixed with Cu2V2O7 precursor powder at a mass ratio of 100:3, and then calcined at 450℃ for 2 hours in air atmosphere to obtain the Cu2V2O7 in-situ modified high-nickel ternary cathode material. Example
[0031] This embodiment provides a method for improving the electrochemical performance and safety of silicon-based anode materials. The silicon-based anode material is a ZrMo2O8 in-situ modified silicon-based anode material, which is prepared using the following steps: The synthesis of the negative thermal expansion material ZrMo2O8 involves combining ZrO(NO3)2·5H2O and N6H... 24 Mo7O 24 ·4H2O was weighed according to the molar ratio of Zr and Mo in ZrMo2O8 and dissolved separately in appropriate amounts of deionized water. After complete dissolution, the ZrO(NO3)2·5H2O aqueous solution was added dropwise to N6H 24 Mo7O 24 The reaction was carried out in a solution of 4H₂O at 55 °C for 4 h. After the reaction was completed, concentrated HCl was added dropwise to the mixture until the precipitate was completely dissolved, and the reaction was continued for another 2 h. Then, after hydrothermal reaction at 180 °C, a white precipitate was obtained, which was washed and dried to obtain the precursor ZrMo₂O₇(OH)₂(H₂O)₂. The silicon-based anode material was thoroughly mixed with Cu₂V₂O₇ precursor powder at a mass ratio of 100:5, and then calcined at 320 °C for 12 h in air atmosphere, followed by cooling to 25 °C. Then, it was calcined at 410 °C for 1.5 h and rapidly cooled to 25 °C to obtain the ZrMo₂O₈ in-situ modified silicon-based anode material.
[0032] Comparative Example 1 uses a co-precipitation method to prepare a cobalt-free lithium-rich manganese-based cathode material with the general chemical formula: Li. 1.2 Mn 0.6 Ni 0.2 O2 is prepared using the following steps: Dissolving NiSO4·6H2O and MnSO4·H2O in deionized water yields 2 mol L-1 50 ml of a transition metal salt solution. NaOH dissolved in deionized water yields 4 mol / L. -1 Prepare 50 ml of a 2 mol / L alkaline solution. - 1 Na₂SO₄ solution was poured into a round-bottom flask, and then heated to 55°C in a water bath for later use. The two solutions were then pumped at 5 mL / min using a peristaltic pump. -1 The solution was simultaneously pumped into a three-necked flask at a rate that allowed for the addition of a 0.5 mol L solution. -1 Ammonia was used as a complexing agent, and the mixture was continuously stirred. The entire process was carried out in an N2 environment with a stirring speed of 800 r / min and a pH maintained at 12. After feeding, the mixture was stirred continuously for 8 hours and aged for 5 hours. Then, it was filtered, washed, and dried at 60℃ for 12 hours to obtain the precursor Mn. 0.75 Ni 0.25 (OH)2. Subsequently, the precursor was thoroughly ground with an excess of 5% LiOH·H2O in a mortar, and sintered at 500℃ and 900℃ for 5h and 12h under O2 atmosphere to obtain cobalt-free lithium-rich manganese-based cathode material. To better react with ZrW2O8, the cobalt-free lithium-rich manganese-based cathode material was calcined at 600℃ for 3h under air atmosphere for heat treatment.
Claims
1. A method for in-situ modification of electrode materials using negative thermal expansion materials, characterized in that, A negative thermal expansion material or its precursor is added during the synthesis of electrode materials, and the electrode material modified in situ by calcination is obtained.
2. A method for in-situ modification of electrode materials using negative thermal expansion materials, characterized in that, The negative thermal expansion material refers to a material that shrinks in volume when heated, and the negative thermal expansion material precursor refers to the substance that is synthesized before the target product, the negative thermal expansion material, is synthesized.
3. A method for in-situ modification of electrode materials using negative thermal expansion materials, characterized in that, The electrode materials mentioned refer to positive electrode materials and negative electrode materials.
4. The method for in-situ modification of electrode materials using negative thermal expansion materials according to claim 1, characterized in that, Includes the following steps: Step 1: According to the molar ratio, dissolve the different raw materials required for the electrode material in deionized water to obtain a mixed metal salt solution; Step 2: Add precipitant solution and complexing agent solution to the metal salt solution obtained in Step 1 to carry out a co-precipitation reaction to obtain the electrode material precursor; Step 3: The electrode material precursor and lithium salt from Step 2 are mixed in stoichiometric ratio and then calcined in an oxygen atmosphere to obtain the electrode material. Step 4: Mix the electrode material from Step 3 with the negative thermal expansion precursor powder in a certain mass ratio, and then calcine to obtain the electrode material modified in situ by the negative thermal expansion material.
5. The method for in-situ modification of electrode materials using negative thermal expansion materials according to claim 2, characterized in that: In step one, the different raw materials required for the electrode material are any one or a combination of oxides, hydroxides, sulfates, acetates, nitrates, and chlorides of the corresponding raw materials.
6. The method for in-situ modification of electrode materials using negative thermal expansion materials according to claim 2, characterized in that: In step two, the precipitant solution includes a sodium hydroxide solution or a sodium carbonate solution.
7. The method for in-situ modification of electrode materials using negative thermal expansion materials according to claim 2, characterized in that: In step two, the complexing agent solution includes one of ammonia, ethylenediaminetetraacetic acid, or sodium citrate solution.
8. A method for in-situ modification of electrode materials using negative thermal expansion materials according to claims 2-5, characterized in that: In step three, the lithium salt includes any one or a combination of lithium hydroxide, lithium carbonate, lithium oxalate, lithium phosphate, lithium dihydrogen phosphate, and lithium hydrogen phosphate.
9. The method for in-situ modification of electrode materials using negative thermal expansion materials according to claim 2, characterized in that, In step three, the calcination is first performed by heating the temperature to 300-500℃ for pre-calcination, and then by heating the temperature to 500-900℃ for calcination.
10. The method for in-situ modification of electrode materials using negative thermal expansion materials according to claim 2, characterized in that, In step four, the mass ratio of the negative thermal expansion material precursor powder to the electrode material is (0.01~20):100).