Multistage interface regulation and control symbiotic phase lithium ion battery composite positive electrode material and preparation method thereof

Abstract

The invention belongs to the technical field of lithium ion battery electrode materials, and particularly relates to a multistage interface regulation and control symbiotic phase lithium ion battery composite positive electrode material and a preparation method thereof. A one-step synthesis strategy is designed, the interaction between a high-nickel eight-series ternary positive electrode material and a spinel type lithium manganate structure is optimized, and Li2WO4 surface coating and W element doping are formed on an interface of the high-nickel eight-series ternary positive electrode material and the spinel type lithium manganate structure, so that the lithium ion battery composite positive electrode material is obtained, and the structural stability and redox reversibility of the composite positive electrode material can be effectively improved. The battery prepared from the composite positive electrode material has high-capacity output, excellent rate capability and cycling stability, and is suitable for high-performance application scenes such as electric automobiles and energy storage systems.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion battery electrode materials, and specifically relates to a multi-level interface-regulated symbiotic phase lithium-ion battery composite positive electrode material and a preparation method thereof, which is applicable to the field of high-energy-density ion power batteries. Background Art

[0002] Lithium-ion batteries, due to their high energy density, long cycle life, and low self-discharge, are widely used in electric vehicles, portable electronic devices, and energy storage systems. As market demand for battery energy density and endurance continues to increase, the performance optimization of cathode materials, the core component of lithium-ion batteries, has become a research hotspot.

[0003] Current high-energy-density lithium-ion batteries face numerous challenges, including poor cycle life, structural instability, and safety concerns under high voltages. While conventional high-nickel layered oxides offer high capacity potential, their interfaces are susceptible to structural collapse and oxygen release. The introduction of spinel lithium manganese oxide structures and interface manipulation strategies can effectively improve their structural stability and electrochemical performance. However, challenges such as poor compatibility between different crystalline phases and limited ion diffusion remain to be addressed.

[0004] Based on this, the present invention devised a one-step synthesis strategy that optimizes the interaction between high-nickel octa-series ternary cathode materials and spinel lithium manganese oxide structures, and forms a Li₂WO₄ surface coating and W doping at their interface. This effectively improves the structural stability and redox reversibility of the composite cathode material. Batteries fabricated using this composite cathode material achieve high-capacity output while exhibiting excellent rate performance and cycling stability, making them suitable for high-performance applications such as electric vehicles and energy storage systems. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the existing technology and propose a multi-level interface-regulated symbiotic phase lithium-ion battery composite positive electrode material and its preparation method, aiming to solve the deficiencies of lithium-ion batteries in the existing technology in terms of long-term cycle stability, wide temperature range, safety, etc.

[0006] Furthermore, the present invention also provides the use of the multi-level interface-regulated symbiotic phase lithium-ion battery composite positive electrode material in the preparation of lithium-ion batteries or lithium-ion secondary batteries.

[0007] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0008] A method for preparing a multi-level interface-regulated symbiotic phase lithium-ion battery composite positive electrode material, which constructs a symbiotic phase positive electrode structure through a multi-level interface regulation strategy and can be used as a positive electrode material for lithium-ion batteries with both high capacity and ultra-long cycle performance.

[0009] The preparation method specifically comprises the following steps:

[0010] 1) grinding and blending the high nickel octa-series ternary cathode material with a lithium source and a W source dopant in a certain proportion to obtain a mixed material I;

[0011] 2) Sintering the mixed material I in step 1) in air or oxygen atmosphere to promote phase transformation and the formation of a symbiotic structure, and finally preparing a composite positive electrode material.

[0012] Furthermore, in step 1), the high nickel eight series ternary positive electrode material is LiNi x M 1-x-y Co y O2, wherein M is at least one of Al, Mn, Mg, Ti, and W, and x≥0.5, 0<y≤1.

[0013] Further preferably, in step 1), the high nickel eight series ternary positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O2.

[0014] Furthermore, in step 1), during mixing, the molar ratio of the high nickel octa-series ternary positive electrode material, the lithium source, and the W source dopant is (1.0-1.1): (0.001-0.005): 0.003.

[0015] Further preferably, in step 1), during mixing, the molar ratio of the high nickel octa-series ternary positive electrode material to the lithium source is 1:(0.001-0.005).

[0016] Further preferably, in step 1), during mixing, the molar ratio of the high nickel octa-series ternary positive electrode material and the W source dopant is (1.0-1.1):0.003.

[0017] Furthermore, in step 1), the lithium source is spinel lithium manganate (LiMn2O4) or lithium nickel manganate (LiNi 0.5 Mn 1.5 O4).

[0018] Furthermore, in step 1), the W source dopant is any one of Li2WO4, WO2 and WO3.

[0019] More preferably, in step 1), ball milling is used for grinding, the ball milling speed is 200-500 rpm, and the grinding time is 2-3 h.

[0020] Furthermore, the sintering temperature in step 2) is 750-850° C., and the sintering time is 8-15 hours.

[0021] Furthermore, the present invention also provides a multi-level interface-regulated symbiotic phase lithium-ion battery composite positive electrode material prepared by the above method.

[0022] Furthermore, based on a general inventive concept, the present invention also provides an application of the multi-level interface-regulated symbiotic phase lithium-ion battery composite positive electrode material in the preparation of lithium-ion batteries or lithium-ion secondary batteries.

[0023] Specifically, when preparing a lithium-ion battery or a lithium-ion secondary battery, a certain amount of the multi-level interface-regulated symbiotic phase lithium-ion battery composite positive electrode material, a conductive agent and an additive are mixed to obtain a mixed powder, which is then mixed with a solvent to obtain a mixed slurry; finally, the mixed slurry is coated on a current collector to make a button-type electrode disc, which is used as the positive electrode, and a metal lithium sheet is used as the negative electrode to assemble a CR2032 button battery.

[0024] Specifically, the conductive agent is at least one of carbon nanotubes, graphene or Super P.

[0025] Specifically, in the obtained mixed slurry, the weight ratio of the multi-level interface-regulated symbiotic phase high-capacity ultra-long cycle lithium-ion battery, the conductive agent and the additive is (80-95): (1-5): (0.5-10).

[0026] Specifically, the solvent is any one of water, anhydrous ethanol and NMP.

[0027] Specifically, the loading amount of the mixed slurry on the prepared electrode disc is 1 to 10 mg / cm 2 .

[0028] Furthermore, based on a general inventive concept, the present invention also provides a lithium ion battery or a lithium ion secondary battery prepared by the above method.

[0029] Compared with the prior art, the advantages of the present invention are:

[0030] 1. The present invention realizes the preparation of high-capacity positive electrode materials of symbiotic phase through multi-level interface control technology. The positive electrode materials are used in lithium-ion batteries, which have the characteristics of high capacity and ultra-long cycle stability, can meet the needs of electric vehicles, portable electronic devices and grid-scale energy storage applications, and significantly improve the performance and service life of the battery.

[0031] 2. High capacity: The multi-level interface-regulated symbiotic phase lithium-ion battery composite cathode material of the present invention is used to prepare lithium-ion batteries, which can achieve an areal capacity of 2.5 mAh / cm at a rate of 0.2C and 25°C. 2 The material can achieve a specific capacity of 220.6 mAh / g and has a capacity retention rate of 97.1% after 100 cycles.

[0032] 3. Excellent cycle performance: The multi-level interface-regulated symbiotic phase lithium-ion battery composite positive electrode material of the present invention was used to prepare a lithium-ion battery. At a rate of 0.2C and 25°C, the capacity retention rate reached 86.4% after 1200 cycles, demonstrating ultra-long cycle stability. After 200 cycles, the discharge capacity was 211.01 mAh / g, with a retention rate of 95.9%.

[0033] 4. The preparation method of the present invention is simple and low-cost, and has low requirements on the equipment and process conditions. The material treated according to a certain coefficient has a higher energy density and is accompanied by better electrochemical performance.

[0034] 5. Industrial adaptability: Parameters such as sintering temperature and doping elements are adapted to existing production lines, which can reduce overall production costs.

[0035] 6. The present invention constructs a stable Li + / e - transmission channel, improving the interface reaction kinetics, and improving the structural stability and reversibility of oxygen redox reaction through W element doping and Li2WO4 surface coating.

[0036] 7. The composite cathode material prepared by the present invention has the characteristics of high capacity output and ultra-long cycle life, achieving a good balance between industrial feasibility and electrochemical performance.

[0037] 8. Safety: The lithium-ion battery prepared by the multi-level interface-regulated symbiotic phase lithium-ion battery composite positive electrode material of the present invention has excellent rate and wide temperature performance and good safety performance, and can meet high energy density and safety requirements.

[0038] 9. Subsequent experiments have shown that the composite cathode material prepared by the present invention can also reach ~3mAh / cm 2 Even higher surface capacity makes it easier to achieve industrial-grade applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the electrochemical performance diagram of the 811NCM&W&LMO composite positive electrode material prepared in Example 1 of the present invention and Example 2. DETAILED DESCRIPTION

[0040] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0041] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are all conventional methods; the reagents, raw materials, etc. used in the following examples are all conventional commercially available products and can be obtained from commercial channels unless otherwise specified.

[0042] In the following examples, the high nickel eight series ternary positive electrode material (LiNi 0.8 Co 0.1 Mn 0.1 The reference for the preparation method of NCM811 Cathodes (Review-Knowledge-Based Process Design for High Quality Production of NCM811 Cathodes[J]. Journal of the Electrochemical Society, 2020, 167(16): 1-12. DOI: 10.1149 / 1945-7111 / abcd11).

[0043] Example 1

[0044] Example 1 provides a method for preparing a multi-level interface-regulated symbiotic phase lithium-ion battery composite positive electrode material, using a one-step solid-phase synthesis method, and the specific steps are:

[0045] 1) High nickel eight series ternary cathode material LiNi 0.8 Co 0.1 Mn 0.1 O2, a lithium source (specifically spinel lithium manganese oxide), and a W source dopant (specifically Li2WO4) were blended in a molar ratio of 1:(0.003):0.003 by ball milling at a ball milling speed of 400 rpm for 2 h to obtain a mixture material I;

[0046] 2) The mixed material I in step 1) is sintered in an oxygen atmosphere (O2 concentration ≥ 95%) at a sintering temperature of 800°C and a sintering time of 10 hours. During the sintering process, W is doped into the lattice to form a Li2WO4 surface coating layer, and together with the pre-introduced LiMn2O4, a stable layered-spinel-coating symbiotic structure is constructed, ultimately preparing an 811NCM&W&LMO composite positive electrode material.

[0047] The preparation method of the present invention introduces a W source in a high-temperature solid-phase reaction to partially dope it into the 811NCM layered structure, simultaneously forming a surface Li2WO4 coating layer and constructing an embedded spinel structure with LiMn2O4, ultimately forming a symbiotic composite positive electrode material.

[0048] The composite cathode material prepared by the present invention has a stable symbiotic structure, good lattice matching between phases (difference <5%), the doping elements do not destroy the stability of the main crystal phase, and the interphase interface energy is lower than 50mJ / m 2 .

[0049] Example 2

[0050] The difference between Example 2 and Example 1 is that the high nickel eight series ternary positive electrode material (Ni 0.8 Co 0.1 Mn 0.1 (OH)2) was directly subjected to electrochemical testing without any treatment.

[0051] Performance Testing

[0052] The product prepared in Example 1 was assembled into a battery and subjected to electrochemical performance testing (test method reference Wang W, Shi Y, Li P. Rational rock-salt phase engineering of a nickel rich layered cathode interface for enhanced rate and cycling stability [J]. Energy & environmental science: EES, 2024, 17 (12): 4283-4294. DOI: 10.1039 / D3EE04110G);

[0053] When assembling the battery, a certain amount of the 811NCM&W&LMO composite positive electrode material, conductive agent and additives are placed in a container to obtain a mixed powder, which is then mixed with a solvent (N-methylpyrrolidone, NMP) to obtain a mixed slurry; finally, the mixed slurry is coated on a copper foil (current collector) (loading amount is 1.5 mg / cm 2 ), a button-type electrode disc with a diameter of 12 mm was made and used as the positive electrode, and a metal lithium sheet was used as the negative electrode to assemble a CR2032 button battery.

[0054] The conductive agent is Super P (Shenzhen Kejing Zhida Technology Co., Ltd., CAS1333-86-4), the additive is polyvinylidene fluoride (PVDF), and the mass ratio of the multi-level interface-regulated symbiotic phase high-capacity ultra-long cycle lithium-ion battery, the conductive agent and the additive in the mixed powder is 90:5:5; the concentration of the mixed powder in the solvent is 500 mg / ml.

[0055] The CR2032 button cell was assembled and charged and discharged at a constant current between 3 and 4.3 V. The test conditions were 0.2 C and 25 ° C to compare the cycle performance of the product prepared in Example 1. The results are shown in Table 1 and Figure 1 As shown, Figure 1 This is the cycle performance curve at a rate of 0.2C.

[0056] from Figure 1 It can be concluded that the CR2032 button battery made of the 811NCM&W&LMO composite positive electrode material prepared by the present invention has a discharge capacity of 220.6mAh / g at 25°C and a 0.2C rate, and has a capacity retention rate of 97.1% after 100 cycles; the capacity retention rate is 86.4% after 1200 cycles at a 0.2C rate; and has excellent cycle stability.

[0057] The multi-level interface-regulated symbiotic phase lithium-ion battery composite cathode material of the present invention has the following advantages:

[0058] 1. Multi-level interface control technology:

[0059] In situ construction of Li + / e - Pathway: By adjusting the bulk / surface interface structure and innovative design, a stable and fast Li2WO4 interface is constructed in situ. + / e - path.

[0060] Promoting the activity of anionic oxygen redox reactions: Through multi-level interface control technology, the reversibility of anionic oxygen redox reactions on the surface of high-nickel VIII series materials at room temperature is enhanced.

[0061] 2. Symbiotic phase high capacity cathode material:

[0062] Lithium manganese oxide (LiMn2O4) cathode materials are considered ideal for lithium-ion batteries due to their high discharge capacity (≥148 mAh / g). They are resource-rich, low-cost, environmentally friendly, safe, and excellent rate performance. Optimizing the bulk / surface interface structure: A one-step synthesis strategy was used to optimize the cathode material's bulk layered / spinel / Li2WO4 / surface interface structure, resulting in the creation of a composite cathode material (811NCM&W&LMO) with a bulk-embedded structure, W doping, and Li2WO4 surface coating.

[0063] 3. Ultra-long cycle stability:

[0064] High areal loading cathode materials: composite cathode materials reach ~3mAh / cm 2 Even higher surface capacity can more easily achieve industrial-grade applications. Capacity retention rate: At 25°C, the surface capacity of the lithium-ion battery made of the 811NCM&W&LMO composite positive electrode material of the present invention at a rate of 0.2C is about 2.5mAh / cm 2, and has a capacity retention rate of 97.1% after 100 cycles; and shows ultra-long cycle stability, with a capacity retention rate of 86.4% after 1200 cycles.

[0065] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a multi-level interface-regulated symbiotic phase lithium-ion battery composite cathode material, characterized in that: The following steps are involved: 1) Grinding and blending the high nickel octa-series ternary cathode material with a lithium source and a W source dopant in a certain proportion to obtain a mixed material I; 2) Sintering the mixed material I in step 1) in air or oxygen atmosphere to promote phase transformation and formation of a symbiotic structure, thereby finally preparing a composite positive electrode material.

2. The preparation method according to claim 1, wherein In step 1), the high nickel eight series ternary cathode material is LiNi x M 1-x-y Co y O2, wherein M is at least one of Al, Mn, Mg, Ti, and W, and x≥0.5, 0<y≤1.

3. The preparation method according to claim 1, wherein In step 1), during mixing, the molar ratio of the high nickel octa-series ternary positive electrode material, the lithium source, and the W source dopant is (1.0-1.1): (0.001-0.005): 0.

003.

4. The preparation method according to claim 1, wherein When mixed, the molar ratio of the high nickel octa-series ternary positive electrode material to the lithium source is 1: (0.001~0.005).

5. The preparation method according to claim 1, wherein In step 1), the lithium source is spinel lithium manganese oxide or lithium nickel manganese oxide.

6. The preparation method according to claim 1, wherein In step 1), the W source dopant is any one of Li2WO4, WO2 and WO3.

7. The preparation method according to claim 1, wherein In step 1), the ball milling method is used for grinding, the ball milling speed is 200-500 rpm, and the grinding time is 2-3 hours.

8. The preparation method according to claim 1, wherein The sintering temperature in step 2) is 750-850°C, and the sintering time is 8-15 hours.

9. A multi-level interface-regulated symbiotic phase lithium-ion battery composite positive electrode material prepared by the method according to any one of claims 1 to 8.

10. Use of the multi-level interface-regulated symbiotic phase lithium-ion battery composite positive electrode material according to claim 9 in the preparation of lithium-ion batteries or lithium-ion secondary batteries.

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