Method for rapidly screening positive electrode material with high temperature long life
By conducting short-term cycle tests at high temperatures and detecting the metal dissolution rate of ternary cathode materials, the problem of long screening cycles in existing technologies has been solved, enabling rapid and accurate screening of cathode materials with long high-temperature lifespans. This method is applicable to ternary layered cathode materials with various nickel-cobalt-manganese ratios.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-27
- Publication Date
- 2026-07-21
AI Technical Summary
Existing technologies make it difficult to quickly and accurately screen ternary cathode materials with excellent high-temperature lifespan from numerous candidate materials, resulting in long research and development cycles and high costs.
By conducting short-term cycle tests at high temperatures, the dissolution rate of the target metal element in the cathode material is detected. The dissolution rate R = (C surface - C bulk phase) / C bulk phase is calculated to screen cathode materials with long high-temperature life.
It enables rapid and accurate screening of cathode materials with long high-temperature lifespan, shortens the R&D cycle, improves R&D efficiency, and is applicable to ternary layered cathode materials with various nickel-cobalt-manganese ratios, and is not affected by differences in the initial state of the materials.
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Figure CN122430362A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium battery material testing technology, specifically a method for rapidly screening cathode materials with long high-temperature lifespan. Background Technology
[0002] Lithium-ion batteries are widely used in 3C products, electric vehicles, and electrochemical energy storage due to their advantages such as high energy density, wide operating temperature range, and low self-discharge rate. Among them, ternary layered cathode materials (LiNi) are particularly important. x Co y Mn z O2 (x+y+z=1) has become a research hotspot due to its high specific capacity and relatively low cost. However, even slight differences in the proportions of nickel, cobalt, and manganese in ternary materials can have a significant impact on their high-temperature cycle life, and the performance differences of many materials are not obvious in the early stages of high-temperature cycling, often requiring hundreds of cycles to become apparent. Existing material screening technologies mainly rely on long-term cycle testing, resulting in long development cycles and high time costs, making it difficult to meet the needs of rapid research and development. Therefore, how to quickly and accurately screen ternary cathode materials with excellent high-temperature life from numerous candidate materials has become a pressing technical challenge in this field. Summary of the Invention
[0003] In view of this, the present invention provides a method for rapidly screening cathode materials with long high-temperature lifespan. By measuring the metal dissolution rate after short-term high-temperature cycling, cathode materials with excellent high-temperature lifespan can be screened quickly and accurately, significantly shortening the material screening cycle and improving R&D efficiency.
[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention discloses a method for rapidly screening cathode materials with long high-temperature lifespan, comprising the following steps: S1. Prepare at least two cathode materials to be tested into cathodes and assemble them into a battery; S2. Perform a high-temperature charge-discharge cycle test on the battery under the same conditions. S3. Detect the dissolution rate R of the target metal element in the positive electrode material of the battery after each cycle test. The calculation formula is: R = (C 表面 -C 体相 ) / C 体相 C 表面 The content of the target metal element on the surface of the cathode material, C 体相 The content of the target metallic element within the bulk phase of the cathode material; S4. Compare the dissolution rate R of each cathode material, and select cathode materials with long high-temperature life based on the relationship between the dissolution rates R.
[0005] As a further aspect of the present invention: the target metallic element is at least one of nickel, cobalt, and manganese.
[0006] As a further aspect of the present invention: in step S2, the temperature of the high-temperature charge-discharge cycle test is 80~110℃, and the number of cycles is 10~20 cycles.
[0007] As a further aspect of the present invention: in step S2, the current density of the high-temperature charge-discharge cycle test is 1 mA / g to 1000 mA / g, and the voltage range is 2 V to 4.5 V.
[0008] As a further aspect of the present invention: the chemical formula of the cathode material is LiNi x Co y Mn z O2, where x+y+z=1.
[0009] As a further aspect of the present invention: the negative electrode material of the battery is at least one of lithium metal, natural graphite, artificial graphite, graphene, mesophase carbon microspheres, amorphous carbon, soft carbon, hard carbon, silicon suboxide, silicon, and lithium titanate.
[0010] As a further aspect of the present invention, the measurement range of the metal dissolution rate (the detection depth from the material surface towards the bulk phase) is 10nm-1000nm.
[0011] As a further aspect of the present invention: in step S4, the process of selecting a cathode material with a long high-temperature lifespan based on the dissolution rate R specifically means that the lower the metal dissolution rate, the longer the high-temperature lifespan of the cathode material.
[0012] Compared with the prior art, the beneficial effects of the present invention are: (1) Fast and efficient: The high-temperature life of the material can be evaluated by short-term cycling (10 weeks) at high temperature. Compared with the traditional long-term cycling test that requires hundreds of weeks, it can save several weeks or even months of testing time and significantly accelerate the research and development process. (2) Accurate and reliable: There is a good correlation between the metal dissolution rate and the high-temperature cycle life of the material. The lower the dissolution rate, the longer the high-temperature cycle life of the material. The screening results are accurate and reliable. (3) Strong universality: It is applicable to various ternary layered cathode materials with nickel, cobalt and manganese ratios, and is not affected by the difference in the initial state of the material (such as crystallinity, morphology, etc.), and has good versatility and promotion value; (4) Easy to operate: It can be completed with only conventional battery assembly, high temperature cycling and elemental analysis equipment. No complicated pretreatment or special consumables are required, and it is easy to promote and apply in research and development and production. Attached Figure Description
[0013] Figure 1This is a comparison curve of the cycle life of four ternary layered cathode materials in Example 1 of the present invention at a high temperature of 100°C. Figure 2 The left image shows the nickel element energy spectrum distribution of the four ternary layered cathode materials in Example 1 of this invention after high-temperature cycling, and the right image shows the change curve of nickel content from the bulk phase to the surface. Figure 2 (a) shows the test results for material 5515; Figure 2 (b) shows the test results for material 613; Figure 2 (c) shows the test results for material 7205; Figure 2 (d) shows the test results for material 7401.
[0014] Figure 3 This is a comparison chart of the nickel dissolution rate and the number of cycles when the discharge cycle capacity drops to 80% of the initial value for the four ternary layered cathode materials in Example 1 of the present invention. Detailed Implementation
[0015] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.
[0016] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
[0017] In addition, unless otherwise specified, the preparation processes in the following embodiments are all conventional methods in the prior art, and therefore will not be described in detail; unless otherwise specified, the parts in the following embodiments refer to parts by weight.
[0018] Example 1 This embodiment provides a method for rapidly screening ternary layered cathode materials with excellent high-temperature cycling stability, specifically including the following steps: (1) Battery assembly Four ternary layered cathode materials with different nickel contents were selected as test subjects, and their chemical formulas are: LiNi 0.55 Co 0.15 Mn 0.3 O2 (hereinafter referred to as 5515), LiNi 0.6 Co 0.1 Mn 0.3 O2 (hereinafter referred to as 613), LiNi0.72 Co 0.05 Mn 0.23 O2 (hereinafter referred to as 7205), LiNi 0.74 Co 0.01 Mn 0.25 O2 (hereinafter referred to as 7401). The above four materials are used to make positive electrode sheets, and CR2032 button cells are prepared according to the same assembly process. The assembly sequence of the battery from bottom to top is as follows: negative electrode shell, lithium metal negative electrode sheet, glass fiber separator, positive electrode sheet, steel gasket, spring sheet, and positive electrode shell. After assembly, an equal amount of electrolyte is injected and the battery is sealed.
[0019] (2) High temperature cycling test The four types of button batteries were subjected to charge-discharge cycle tests in a constant temperature environment of 100℃. The test conditions were: charging cut-off voltage 4.4V, discharging cut-off voltage 2.8V, and charge / discharge current density of 200mA / g. All batteries were cycled for 10 cycles under the above conditions before the test was stopped.
[0020] (3) Metal dissolution rate detection The cycled battery was disassembled in an inert atmosphere glove box. The positive electrode was removed and cleaned with anhydrous dimethyl carbonate (DMC) to remove residual electrolyte. After drying, a transmission electron microscope (TEM) sample was prepared. Elemental distribution analysis of the material particles was performed using an energy dispersive spectroscopy (EDS) instrument mounted on the TEM. During testing, a cross-sectional area of the material particles was selected, and a radial line scan was performed from the particle surface to the bulk phase interior at a depth of 80 nm. The nickel content at the outermost layer (0 nm) and the bulk phase interior (80 nm) was recorded, denoted as C. 表面 and C 体相 The nickel dissolution rate R of each material is calculated according to the following formula: R = (C 表面 - C 体相 ) / C 体相 × 100% The nickel content test results and leaching rate calculation values of the four materials are shown in Table 1.
[0021] Table 1
[0022] Note: The nickel content in bulk and surface phases is a mass fraction (in decimals).
[0023] (4) High-temperature life verification To verify the correlation between the above-mentioned dissolution rate and the high-temperature lifespan of the materials, another batch of fresh batteries from the same period were subjected to long-term cycle testing under the same test conditions as in step (2) (100℃, 4.4V-2.8V, 200mA / g) until the battery discharge capacity decayed to 80% of the initial value, and the number of cycles for each material was recorded. The test results are as follows: Figure 1 As shown, the order of the number of cycles for the four materials to reach 80% capacity decay is: 613 > 7401 > 7205 > 5515.
[0024] (5) Results Analysis Figure 3 The image shows the energy dispersive spectral density (EDS) distribution of nickel in four materials after 10 weeks of high-temperature cycling (left) and the nickel content variation curve from the bulk phase to the surface (right). From... Figure 2 As can be seen from the data in Table 1, the nickel dissolution rate of the four materials is ranked as follows: 613 (-9.8%) > 7401 (-11.6%) > 7205 (-13.3%) > 5515 (-15.2%). That is, the smaller the absolute value of the nickel dissolution rate (the less negative it is), the less nickel is dissolved in the material.
[0025] The above nickel dissolution rates are ranked in order of long-term cycle life. Figure 1 For example, to make a comparison, Figure 3 As shown, the two exhibit a highly consistent correlation: the lower the nickel dissolution rate (the smaller the negative value), the longer the number of cycles required for the material to reach 80% capacity decay at high temperatures, i.e., the longer the high-temperature lifetime. This result indicates that by measuring the transition metal dissolution rate of materials after short-term cycling at high temperatures, ternary layered cathode materials with excellent high-temperature lifetimes can be effectively predicted and screened.
[0026] This embodiment 1 verifies the feasibility and accuracy of the method of the present invention, proving that only 10 weeks of high-temperature cycling is needed to achieve rapid assessment of the high-temperature life of materials. Compared with the traditional long-term cycling test that requires hundreds of weeks, it can significantly shorten the screening cycle and significantly improve R&D efficiency.
[0027] Example 2 This embodiment provides a method for rapidly screening ternary layered cathode materials with excellent high-temperature cycling stability, specifically including the following steps: (1) Battery assembly Four ternary layered cathode materials, the same as those in Example 1, were selected: LiNi 0.55 Co 0.15 Mn 0.3 O2 (5515), LiNi 0.6 Co 0.1 Mn 0.3 O2 (613), LiNi 0.72 Co 0.05 Mn 0.23O2 (7205), LiNi 0.74 Co 0.01 Mn 0.25 O2 (7401). Positive electrode sheets were fabricated using the same process as in Example 1 and assembled into CR2032 button cells. The assembly sequence, electrolyte injection volume, and sealing method were all the same as in Example 1.
[0028] (2) High temperature cycling test The four types of button batteries were subjected to charge-discharge cycle tests in a constant temperature environment of 110℃. The test conditions were: charging cut-off voltage 4.4V, discharging cut-off voltage 2.8V, and charge / discharge current density of 1000 mA / g. All batteries were cycled for 10 cycles under the above conditions before the test was stopped.
[0029] (3) Metal dissolution rate detection The cycled battery was disassembled in an inert atmosphere glove box. The positive electrode was removed and cleaned with anhydrous dimethyl carbonate (DMC) to remove residual electrolyte. After drying, a transmission electron microscope (TEM) sample was prepared. Elemental distribution analysis of the material particles was performed using an energy dispersive spectroscopy (EDS) instrument mounted on the TEM. During testing, a cross-sectional area of the material particles was selected, and a radial line scan was performed from the particle surface to the bulk phase interior at a depth of 80 nm. The nickel content at the outermost layer (0 nm) and the bulk phase interior (80 nm) was recorded, denoted as C. 表面 and C 体相 The nickel dissolution rate R of each material is calculated according to the following formula: R = (C 表面 - C 体相 ) / C 体相 × 100% Table 2
[0030] The test results and calculated dissolution rates are shown in Table 2.
[0031] (4) High-temperature life verification To verify the correlation between the dissolution rate and the high-temperature lifespan of the materials, another batch of fresh batteries from the same period were subjected to long-term cycling tests under the same test conditions as in step (2) (110℃, 4.4V-2.8V, 1000 mA / g) until the battery discharge capacity decayed to 80% of the initial value, and the number of cycles for each material was recorded. The test results showed that the order of the number of cycles to 80% capacity decay for the four materials was consistent with the order of nickel dissolution rate: the lower the nickel dissolution rate (the smaller the negative value), the longer the high-temperature cycling life of the material.
[0032] 5) Results Analysis As can be seen from the data in Table 2, under the test conditions of 110℃ and 1000 mA / g, the nickel dissolution rate of the four materials is ranked as follows: 613 (-11.8%) > 7401 (-13.2%) > 7205 (-15.6%) > 5515 (-20.3%). That is, the smaller the absolute value of the nickel dissolution rate (the less negative it is), the less nickel is dissolved in the material.
[0033] Comparing the above nickel dissolution rate ranking with the long-term cycle life verification results, a highly consistent correlation is found: the lower the nickel dissolution rate (the smaller the negative value), the longer the number of cycles required for the material to reach 80% capacity decay at high temperature, i.e., the longer the high-temperature life. This result indicates that even under more stringent test conditions (110℃, 1000 mA / g), measuring the transition metal dissolution rate of materials after short-term cycling at high temperature can still effectively predict and screen ternary layered cathode materials with excellent high-temperature life.
[0034] This embodiment verifies that even at higher temperatures (110°C) and higher current densities (1000 mA / g), the method of the present invention can still accurately and quickly screen for cathode materials with long high-temperature lifetimes based on the nickel dissolution rate after short-term cycling.
[0035] Example 3 This embodiment provides a method for rapidly screening ternary layered cathode materials with excellent high-temperature cycling stability, specifically including the following steps: (1) Battery assembly Four ternary layered cathode materials, the same as those in Example 1, were selected: LiNi 0.55 Co 0.15 Mn 0.3 O2 (hereinafter referred to as 5515), LiNi 0.6 Co 0.1 Mn 0.3 O2 (hereinafter referred to as 613), LiNi 0.72 Co 0.05 Mn 0.23 O2 (hereinafter referred to as 7205), LiNi 0.74 Co 0.01 Mn 0.25 O2 (hereinafter referred to as 7401). Positive electrode sheets were prepared according to the same process as in Example 1 and assembled into CR2032 button cells. The assembly sequence, electrolyte injection amount and sealing method were the same as in Example 1.
[0036] (2) High temperature cycling test The four types of button batteries were subjected to charge-discharge cycle tests in a constant temperature environment of 80°C. The test conditions were: charging cut-off voltage 4.4V, discharging cut-off voltage 2.8V, and charge / discharge current density of 1 mA / g. All batteries were cycled for 10 cycles under the above conditions before the test was stopped.
[0037] (3) Metal dissolution rate detection The cycled battery was disassembled in an inert atmosphere glove box. The positive electrode was removed and cleaned with anhydrous dimethyl carbonate (DMC) to remove residual electrolyte. After drying, a transmission electron microscope (TEM) sample was prepared. Elemental distribution analysis of the material particles was performed using an energy dispersive spectroscopy (EDS) instrument mounted on the TEM. During testing, a cross-sectional area of the material particles was selected, and a radial line scan was performed from the particle surface to the bulk phase interior at a depth of 80 nm. The nickel content at the outermost layer (0 nm) and the bulk phase interior (80 nm) was recorded, denoted as C. 表面 and C 体相 The nickel dissolution rate R of each material is calculated according to the following formula: R = (C 表面 - C 体相 ) / C 体相 × 100% The nickel content test results and leaching rate calculation values of the four materials are shown in Table 3.
[0038] Table 3
[0039] (4) High-temperature life verification To verify the correlation between the dissolution rate and the high-temperature lifespan of the materials, another batch of fresh batteries from the same period were subjected to long-term cycling tests under the same test conditions as in step (2) (80℃, 4.4V-2.8V, 1 mA / g) until the battery discharge capacity decayed to 80% of the initial value, and the number of cycles for each material was recorded. The test results showed that the order of the number of cycles for the four materials to reach 80% capacity decay was consistent with the order of nickel dissolution rate: the lower the nickel dissolution rate (the smaller the negative value), the longer the high-temperature cycling life of the material.
[0040] As can be seen from the data in Table 3, under the test conditions of 80℃ and 1 mA / g, the nickel dissolution rate of the four materials is ranked as follows: 613 (-8.7%) > 7401 (-9.6%) > 7205 (-10.9%) > 5515 (-12.5%). That is, the smaller the absolute value of the nickel dissolution rate (the less negative it is), the less nickel is dissolved in the material.
[0041] Comparing the above nickel dissolution rate ranking with the long-term cycle life verification results, a highly consistent correlation is observed: the lower the nickel dissolution rate (the smaller the negative value), the longer the number of cycles required for the material to reach 80% capacity decay at high temperature, i.e., the longer the high-temperature lifetime. This result indicates that, under relatively mild test conditions (80℃, 1 mA / g), measuring the transition metal dissolution rate of materials after short-term cycling at high temperatures can also effectively predict and screen ternary layered cathode materials with excellent high-temperature lifetime.
[0042] This embodiment verifies that even at lower temperatures (80°C) and lower current densities (1 mA / g), the method of the present invention can still accurately and quickly screen for cathode materials with long high-temperature lifetimes based on the nickel dissolution rate after short-term cycling, indicating that the method has good applicability and stability.
[0043] Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
[0044] Therefore, the above description is only a preferred embodiment of this application and is not intended to limit the scope of this application; that is, all equivalent modifications made in accordance with the scope of the claims of this application shall be within the protection scope of the claims of this application.
Claims
1. A method for rapidly screening cathode materials with long high-temperature lifespan, characterized in that, Includes the following steps: S1. Prepare at least two cathode materials to be tested into cathodes and assemble them into a battery; S2. Perform a high-temperature charge-discharge cycle test on the battery under the same conditions. S3. After the cycle test, the dissolution rate R of the target metal element in the positive electrode material of the battery is detected. The calculation formula is: R = (C 表面 -C 体相 ) / C 体相 C 表面 The content of the target metal element on the surface of the cathode material, C 体相 The content of the target metallic element within the bulk phase of the cathode material; S4. Compare the dissolution rate R of each cathode material, and select cathode materials with long high-temperature life based on the relationship between the dissolution rates R.
2. The method according to claim 1, characterized in that, The target metallic element is at least one of nickel, cobalt, and manganese.
3. The method according to claim 1, characterized in that, In step S2, the temperature of the high-temperature charge-discharge cycle test is 80~110 ℃, and the number of cycles is 10~20 cycles.
4. The method according to claim 1, characterized in that, In step S2, the current density of the high-temperature charge-discharge cycle test is 1 mA / g to 1000 mA / g, and the voltage range is 2 V to 4.5 V.
5. The method according to claim 1, characterized in that, The chemical formula of the cathode material is LiNi. x Co y Mn z O2, where x+y+z=1.
6. The method according to claim 1, characterized in that, The negative electrode material of the battery is at least one of lithium metal, natural graphite, artificial graphite, graphene, mesophase carbon microspheres, amorphous carbon, soft carbon, hard carbon, silicon suboxide, silicon, and lithium titanate.
7. The method according to claim 1, characterized in that, In step S4, the process of selecting cathode materials with long high-temperature lifespan based on the dissolution rate R specifically means that the lower the metal dissolution rate, the longer the high-temperature lifespan of the cathode material.