Preparation method and application of W-Y composite coated NCM613 positive electrode material
By constructing a WY composite coating layer on the surface of NCM613 cathode material, the problem of interfacial and bulk instability of the material in lithium-ion batteries was solved, and the high electrochemical performance and structural stability of the material were improved, especially the excellent cycle performance under high temperature conditions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CENTRAL SOUTH UNIVERSITY OF FORESTRY AND TECHNOLOGY
- Filing Date
- 2026-01-14
- Publication Date
- 2026-05-01
AI Technical Summary
In the prior art, NCM613 cathode material exhibits interfacial and bulk instability during cycling in lithium-ion batteries, leading to a rapid decline in cycling performance and structural stability. A single W-based or rare earth coating layer is insufficient in terms of modification effect.
A WY composite coating layer was constructed on the surface of NCM613 material using a nano-tungstic acid and yttrium dioxide composite as the coating material. The dense WY composite coating layer was formed by high-temperature sintering, which enhanced the structural stability and electrochemical performance of the material.
The discharge specific capacity, first efficiency, and high-rate capacity of NCM613 material at 0.1C were significantly improved, as were the cycling performance and structural stability at high temperatures. The discharge specific capacity at 0.1C increased from 164.3 mAh·g⁻¹ to 174.9 mAh·g⁻¹, the first efficiency increased from 78.45% to 84.46%, the high-rate capacity at 5C increased from 23.2 mAh·g⁻¹ to 95 mAh·g⁻¹, and the capacity retention after 100 cycles at 1C at 60℃ increased from 16.0% to 66.1%.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-ion batteries and relates to a method for preparing WY composite coated NCM613 cathode material and its application. Background Technology
[0002] With the rapid development of the new energy vehicle industry, the comprehensive demand for lithium-ion battery cathode materials in terms of high energy density, long cycle life, and low cost is becoming increasingly urgent. Medium-high nickel ternary layered oxides, such as LiNi, are being developed. 0.6 Co 0.1 Mn 0.3 O2 (NCM613) has become one of the key materials in current power battery systems due to its balanced energy density and safety. However, with the increase of nickel content, Li... + with Ni 2+ Cation mixing easily occurs between them, resulting in the loss of active sites; during the repeated insertion and extraction of lithium ions, the cell volume change intensifies, which easily induces the generation of microcracks and harmful phase transformations, leading to a rapid decline in cycle performance and structural stability. To overcome the above bottlenecks, effective modification research on NCM613 materials has become an important direction to promote its practical application.
[0003] Currently, the main methods to improve the electrochemical performance of materials are surface coating and elemental doping modification. Elemental doping can enhance the structural stability of cathode materials. Existing research shows that doping ions include Na. + Y 3+ F - Such substances are typically used to inhibit structural degradation and improve Li + Conductivity. Surface coating processes reduce direct contact between the material and the electrolyte by constructing a coating layer on the material surface, thereby mitigating side reactions at the electrode / electrolyte interface. Traditional single coatings, such as TiO2 and Al2O3, primarily improve cross-sectional stability to some extent by acting as a physical barrier to isolate the material from the electrolyte. However, these coatings have limited inhibitory effects on the degradation of deep bulk structures, and their modification effects require more precise control over process parameters (sintering temperature, time, coating amount, etc.), posing challenges to process reproducibility and scalability.
[0004] In recent years, tungsten-based coatings have attracted widespread attention due to their unique properties. Studies have shown that tungsten (W) can not only form stable interfacial layers (such as WO3 and Li2WO4), but also potentially dope the lattice surface at high temperatures, thereby synergistically improving the stability of the interface and near-surface region. For example, Song et al. reported that WO3 coatings effectively improved the cycling performance of NCM622 (Guowen Song, Hui Zhong, Yanyang Dai, et al. WO3 membrane-encapsulated layered LiNi).0.6 Co 0.2 Mn 0.2 O2 cathode material for advanced Li-ion batteries[J]. Ceramics International, 2019, 45(6): 6774-6781). Nevertheless, the effect of single W-based coating on the bulk phase of the material, especially the suppression of Li⁺ / Ni²⁺ mixing, is still insufficient.
[0005] To overcome these challenges, rare earth element coating technology has emerged. Due to their unique 4f electron shell structure and large ionic radius, rare earth elements exhibit unique advantages in stabilizing layered oxide crystal frameworks and suppressing cation mixing. Wang et al. used Eu2O3 to coat single-crystal NCM613, effectively improving the material's structural reversibility (Zhuang Wang, Xiangyun Qiu, Jilei Du, et al. Investigation of surface engineering on single-crystal NCM613 cathode through Eu2O3 coating to enhance performances[J]. Journal of Alloys and Compounds, 2025, 1033). However, while such single rare earth coatings can effectively consolidate the bulk phase, their physical isolation performance and optimization ability for interfacial ion transport are generally weaker than those of W-based coatings. Summary of the Invention
[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing WY composite-coated NCM613 cathode material and its application. By using a nano-tungstic acid and yttrium dioxide composite as the coating material, a WY composite coating layer is constructed on the surface of NCM613 material, thus developing a high-performance, high-stability high-nickel ternary cathode material.
[0007] To achieve the above objectives, the present invention provides the following technical solution:
[0008] This invention provides a method for preparing WY composite-coated NCM613 cathode material, comprising the following steps:
[0009] (1) Mix nano-tungstic acid and yttrium oxide in a predetermined ratio to obtain the WY composite precursor;
[0010] (2) Mix the NCM613 active material with the WY composite precursor obtained in step (1) according to a set ratio, and after thorough grinding, obtain a uniform mixture;
[0011] (3) Place the mixture obtained in step (2) in a tube furnace and sinter it at 600~800℃ for 1~4 hours under an inert atmosphere. Then grind the sintered product after cooling in the furnace to obtain WY composite coated NCM613 cathode material.
[0012] In the preferred embodiment, in step (1), nano-tungstic acid and yttrium oxide are added to a planetary ball mill at a W:Y molar ratio of 1:0.05~0.25 and ball-milled at a speed of 200~1000 rpm for 2~24 hours.
[0013] In a preferred embodiment, in step (2), the NCM613 active substance and the WY composite precursor obtained in step (1) are mixed at a molar ratio of 1:0.001~0.01.
[0014] In the preferred embodiment, in step (3), the temperature is raised to 700°C and sintered for 2 hours under the protection of an argon atmosphere.
[0015] The present invention also provides the application of the WY composite-coated NCM613 cathode material in lithium-ion batteries.
[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0017] LiNi 0.6 Co 0.1 Mn 0.3 The commercial application of O2 (NCM613) is limited by its interfacial and bulk instability during cycling. This invention proposes a WY composite-coated NCM613 cathode material, which constructs a more uniform and dense WY composite coating layer compared to single W coating. The WY composite-coated NCM613 material exhibits significantly optimized electrochemical performance, with a discharge specific capacity of 164.3 mAh·g at 0.1C. -1 Increased to 174.9 mAh·g -1 The first-efficiency performance increased from 78.45% to 84.46%, and the 5C high-rate capacity increased from 23.2 mAh·g. -1 Increased to 95mAh·g -1 After 100 cycles at 60°C and 1C, the capacity retention rate increased from 16.0% to 66.1%. Attached Figure Description
[0018] Figure 1 XRD patterns of NCM613, NCM613@0.3%W and NCM613@0.3%WY samples;
[0019] Figure 2 for Figure 1 A magnified view of a portion of the (003) diffraction peak;
[0020] Figure 3 SEM images of NCM613 (A,a), NCM613@0.3%W (B,b) and NCM613@0.3%WY (C,c) at different magnifications;
[0021] Figure 4 HAADF-STEM and HRTEM images of NCM613(b) and NCM613@0.3%WY(a, c, d), and elemental mappings of Ni, Co, Mn, W and Y of NCM613@0.3%WY (e, f).
[0022] Figure 5 Initial charge-discharge curves at 0.1C for NCM613, NCM613@0.3%W and NCM613@0.3%WY (a), rate capacity from 0.1 to 5C (b), 0.2C cycle performance (c), and discharge characteristics of NCM613 and NCM613@0.3%WY after different cycles (d).
[0023] Figure 6 Cyclic performance of NCM613 and NCM613@0.3%WY at 60°C;
[0024] Figure 7 The CV curves are for NCM613 (a) and NCM613@0.3%WY (b). Detailed Implementation
[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0026] Unless otherwise specified, all reagents used in this embodiment are commercially available products or prepared by conventional means, and all equipment used is conventional equipment in the art. The following are some examples from the inventors' experiments:
[0027] Example 1
[0028] Nano-tungstic acid (H2WO3, Xinda New Materials Technology) and yttrium oxide (Y2O3, Suzhou Yuante New Materials) were placed in a planetary ball mill at a W:Y molar ratio of 1:0.15 and ball-milled at 600 rpm for 12 hours to obtain a uniform WY composite precursor. NCM613 active material and the WY composite precursor were weighed at a molar ratio of 1:0.003 and thoroughly ground and mixed to obtain a uniform mixture of NCM613 and the WY composite precursor. The mixture was placed in a tube furnace and sintered at 700℃ for 2 hours under argon atmosphere protection. The sintered product, after cooling in the furnace, was ground again to obtain a WY composite-coated NCM613@0.3%WY sample.
[0029] Comparative Example 1
[0030] The active material NCM613 and H2WO4 were weighed at a molar ratio of 1:0.003 and thoroughly ground and mixed to obtain a homogeneous mixture of NCM613 and nano-tungstic acid. The mixture was placed in a tube furnace and sintered at 700°C for 2 hours under argon atmosphere protection. The sintered product after furnace cooling was ground again to obtain a single W-coated NCM613@0.3%W sample.
[0031] Example 2
[0032] Nano-tungstic acid (H2WO3, Xinda New Materials Technology) and yttrium oxide (Y2O3, Suzhou Yuante New Materials) were placed in a planetary ball mill at a W:Y molar ratio of 1:0.25 and ball-milled at 1000 rpm for 2 hours to obtain a uniform WY composite precursor. NCM613 active material and the WY composite precursor were weighed at a molar ratio of 1:0.01 and thoroughly ground and mixed to obtain a uniform mixture of NCM613 and the WY composite precursor. The mixture was placed in a tube furnace and sintered at 800℃ for 1 hour under argon atmosphere protection. The sintered product, after furnace cooling, was ground again to obtain a WY composite-coated NCM613@1%WY sample.
[0033] Example 3
[0034] Nano-tungstic acid (H2WO3, Xinda New Materials Technology) and yttrium oxide (Y2O3, Suzhou Yuante New Materials) were placed in a planetary ball mill at a W:Y molar ratio of 1:0.05 and ball-milled at 200 rpm for 24 hours to obtain a uniform WY composite precursor. NCM613 active material and the WY composite precursor were weighed at a molar ratio of 1:0.001 and thoroughly ground and mixed to obtain a uniform mixture of NCM613 and the WY composite precursor. The mixture was placed in a tube furnace and sintered at 600℃ for 4 hours under argon atmosphere protection. The sintered product, after furnace cooling, was ground again to obtain a WY composite-coated NCM613@0.1%WY sample.
[0035] Materials testing:
[0036] Powder XRD analysis was performed using a Rigaku Ultima IV diffractometer (Rigaku Corporation, Japan; the light source was a Cu target with a wavelength of 1.5418 Å; the tube voltage and tube current were 40 kV and 40 mA, respectively). Scanning electron microscopy (SEM, Hitachi SU8600), transmission electron microscopy (TEM, JEM-F200), and energy-dispersive X-ray spectroscopy (EDS, Ultim Max80) were used to characterize the morphology, microstructure, and elemental distribution of the samples, respectively.
[0037] Electrochemical performance testing:
[0038] The positive electrode active material, polyvinylidene fluoride (PVDF) binder (battery grade), and acetylene black (battery grade) conductive agent were weighed out in a mass ratio of 8:1:1, with N-methylpyrrolidone (NMP, battery grade) as the solvent. After magnetic stirring and mixing, the slurry was evenly coated onto aluminum foil. The coated electrode sheet was then dried in a vacuum drying oven at 110°C for 12 hours. The electrode sheet was cut into 16mm diameter discs. Using the self-made electrode sheet as the positive electrode and a lithium metal sheet as the negative electrode, a CR2016 coin cell was assembled in an argon-filled glove box. The battery was charged and discharged using a LAND charge / discharge testing system (Wuhan Landian Electronics Co., Ltd.). The voltage range was 2.8~4.3V, the ambient temperature was 25°C, and 1C = 160mAh·g. -1 .
[0039] Figure 1 The XRD patterns of the NCM613, NCM613@0.3%W, and NCM613@0.3%WY samples are shown below. Figure 1 As shown, the two coated and modified samples exhibit the same diffraction peaks as NCM613, indicating that the surface coating did not change the α-NaFeO2 layered structure (R-3m space group) of the material matrix. Figure 1 No obvious diffraction peaks of H2WO3 and Y2O3 were observed, which may be due to the low content of the coating layer, the high dispersion of the coating, or the existence of the coating layer in an amorphous form.
[0040] Depend on Figure 2 It can be seen that the (003) diffraction peak of the modified material shifts slightly to a higher angle, while the (006) / (102,108) / (110,101) diffraction peaks show almost no shift. This indicates that during the high-temperature treatment at 700℃, trace amounts of W / Y ions diffused and doped into the surface lattice of NCM613. The mechanism can be explained by W... 6+ The ionic radius of (0.60 Å) is smaller than that of Ni. 3+(0.56Å, low spin) / Co 3+ (0.545Å) / Mn 4+ (0.53Å), when the price W 6+ When doping enters the transition metal site, in order to maintain charge balance, cation vacancies or Li ions are created. + The loss of crystals causes lattice contraction, resulting in the shift of diffraction peaks to higher angles.
[0041] The lattice parameters of the three samples obtained by Rietveld are shown in Table 1. Compared with the unmodified NCM613, the cell parameters a and c of the coated samples both showed a decreasing trend. The cell parameters a of NCM613@0.3%WY decreased from 2.8751 Å to 2.8723 Å, and c decreased from 14.2391 Å to 14.2267 Å, resulting in a shrinkage of the cell volume V from 101.936 ų to 101.652 ų, confirming the lattice shrinkage effect caused by W / Y doping. Meanwhile, the c / a values of all three were greater than 4.9, with NCM613@0.3%WY having the largest c / a ratio, indicating that the layered structure of the material was not damaged. Furthermore, the I(003) / I(104) ratio increased from 1.75 for NCM613 to 1.95 for NCM613@0.3%WY, both exceeding 1.2. This demonstrates that the cationic Li in the NCM613@0.3%WY modified sample... + / Ni 2+ The degree of mixing was effectively suppressed.
[0042] Table 1. XRD Retrieved Refinement Results of NCM613, NCM613@0.3%W and NCM613@0.3%WY
[0043] Sample a(Å) c(Å) c / a <![CDATA[V / Å 3 ]]> I(003) / I(104) NCM613 2.8751 14.2391 4.9525 101.936 1.75 NCM613@0.3%W 2.8743 14.2355 4.9526 101.882 1.82 NCM613@0.3%WY 2.8723 14.2267 4.9530 101.652 1.95
[0044] Figure 3 The surface morphology of NCM613, NCM613@0.3%W, and NCM613@0.3%WY is shown below. Figure 3 (A, a) As can be seen, the uncoated NCM613 secondary spheres are composed of tightly packed primary nanoparticles, exhibiting a clear porous network structure with a smooth surface and well-defined contours. This morphology is beneficial for electrolyte wetting, but it also provides numerous active sites for side reactions. Figure 3(B, b) As can be seen, while the secondary spheres of the NCM613@0.3%W material maintained their basic morphology, their surface underwent significant changes. Numerous fine nanoparticles were observed adhering to the surface, blurring the originally clear mesh structure and reducing surface porosity. This indicates that a new phase or modification layer was formed on the material surface through the coating, covering part of the original structure. However, this coating layer is not sufficiently continuous and dense, and some areas still show exposed NCM613 surface. Figure 3 As shown in (C, c), the NCM613@0.3%WY material exhibits a greater amount of deposits on its surface compared to the NCM613@0.3%W material, forming a denser and more uniform coating layer. This indicates that the addition of Y element has a synergistic effect with W, promoting a more uniform growth of the lithium tungstate (Li2WO4)-based coating phase. This ultimately formed complete coating layer acts as an effective physical barrier, more effectively isolating the active material from the electrolyte and thus suppressing interfacial side reactions.
[0045] Figure 4 b shows an HR-TEM image of uncoated NCM613, with a clean surface and only a continuous and regular bulk NCM613 structure with lattice fringes observed. This contrasts sharply with... Figure 4 As clearly shown in a, c, and d, a uniform coating layer of approximately 10-15 nm was successfully constructed on the surface of the NCM613@0.3%WY secondary particles. This coating layer has a clear and tight interface with the internal NCM613 substrate, indicating the formation of a stable interface during the high-temperature heat treatment process. Figure 4 (c,d) It can be observed that the coating layer region exhibits lattice fringes different from the internal NCM613 body. There are two main types of typical lattice fringes: one with a spacing of about 0.267 nm, which, compared with the standard PDF card (JCPDS No. 00-012-0763), is highly consistent with the (112) crystal plane of lithium tungstate (Li2WO4); the other with a spacing of about 0.184 nm, whose measured value is similar to the main crystal plane spacing of the precursor Y2O3, and may be a new phase such as yttrium lithium oxide (such as LiYO2) or yttrium tungstate composite oxide formed at high temperature. Due to Y 3+ The doping amount is extremely small and may exist in an amorphous or highly dispersed form, making it difficult to definitively identify as a single phase by TEM. However, this result is consistent with EDS scanning ( Figure 4The detection of Y element in f) confirms that Y element has been successfully introduced and integrated into the surface coating layer. These results indicate that the WY composite coating layer is not a simple mixture of WO3 and Y2O3, but rather a composite protective layer primarily composed of crystalline Li2WO4 and possibly containing yttrium compound nanocrystals. To visually demonstrate the distribution of the coating elements, HAADF-STEM imaging and corresponding EDS elemental surface scanning analysis were performed. Figure 4 (e, f). The results show that the signals of Ni, Co, and Mn elements are uniformly distributed throughout the entire secondary sphere, reflecting the homogeneity of the original material. The signal intensities of W and Y elements are significantly enhanced at the particle edges, and their distribution profiles perfectly coincide with those of Ni, Co, and Mn. This indicates that W and Y elements have been successfully and uniformly modified on the surface of NCM613 particles, forming a complete coating layer, which is completely consistent with the observations of HR-TEM. In summary, a uniform and dense WY composite nanocoating layer with a thickness of approximately 10-15 nm, mainly composed of Li₂WO₄ and well-bonded to the substrate, has been successfully constructed on the surface of NCM613 material. This coating layer is a key structure for improving the electrochemical performance of NCM613 material.
[0046] Figure 5 (a) shows the first charge-discharge curves of the three materials at 0.1C. It can be seen that NCM613, CM613@0.3%W and NCM613@0.3%WY materials have 164.3, 165.9 and 174.9 mAh·g, respectively. -1 Among the three materials, NCM613@0.3%WY exhibits the highest capacity. Their coulombic efficiencies are 81.9%, 84.3%, and 84.46%, respectively, with NCM613@0.3%WY showing a slightly higher efficiency. This is primarily attributed to the WY composite coating layer. This dense coating layer effectively isolates the highly active delithiated cathode material from direct contact with the electrolyte, thereby suppressing interfacial side reactions (such as electrolyte oxidation and decomposition) occurring under high voltage during the first charging cycle. This reduces the resulting loss of active lithium ions and transition metal ions, allowing more lithium ions to reversibly re-intercalate into the crystal lattice during discharge. Figure 5 (b) shows the rate performance of the three materials at 0.1, 0.2, 0.5, 1, 2, 5, and 0.2C rates. It is clear from the figure that NCM613@0.3%WY exhibits superior rate performance. As the current density increases, the capacity of all materials decreases, but NCM613@0.3%WY maintains the highest capacity retention, indicating its superior structural stability and conductivity. Especially at a high rate of 5C, its discharge specific capacity is 95 mAh·g. -1 This is significantly higher than the uncoated NCM613, which has a capacity of only 23.2 mAh·g. -1When the discharge rate recovers to 0.2C, the NCM613@0.3%WY capacity can still recover to 166.8 mAh·g. -1 This indicates that it possesses better electrochemical reversibility and structural stability, and also demonstrates that the composite coating significantly improves the ion and electron transport kinetics at the electrode interface. On the one hand, the coating suppresses the severe interfacial side reactions and the growth of thick and uneven CEI films at high rates, reducing charge transfer impedance; on the other hand, W 6+ and Y 3+ During high-temperature processing, lithium ions may diffuse to the surface of the crystal lattice. Their high valence state may introduce more lithium vacancies or improve the electronic conductivity of the material, which together promote the rapid insertion and extraction of lithium ions and the migration of electrons. Figure 5 (c) shows the three materials under long-cycle testing at 0.2C rate. The unmodified NCM613 material exhibits the most rapid capacity decay, indicating that its structure suffers irreversible damage during repeated lithium-ion insertion and extraction. In contrast, the modified materials, especially NCM613@0.3%WY, demonstrate superior cycle durability, with the highest specific capacity throughout the cycle. Furthermore, the coulombic efficiency of NCM613@0.3%WY is not only higher in the first cycle but also remains consistently close to 100% throughout the entire cycle. Figure 5 (d) shows the voltage-cycle relationship curves of NCM613 and NCM613@0.3%WY after different cycle numbers. The discharge voltage plateau of NCM613@0.3%WY decreases slowly with increasing cycle number, while the plateau of NCM613 decreases rapidly, indicating that an appropriate amount of WY coating can reduce voltage decay during cycling. Furthermore, the capacity decay of NCM613@0.3%WY under different cycles is relatively slower than that of uncoated NCM613. Based on the above results, the WY composite coating not only inhibits continuous interfacial side reactions and active material corrosion through physical isolation, but more importantly, it effectively stabilizes the bulk crystal structure of the material, slowing down the occurrence of harmful phase transformations (such as the transformation from layered to spinel / rock salt phase) and the propagation of microcracks. This is the fundamental reason why its capacity and voltage retention rates are far superior to those of the uncoated sample.
[0047] To investigate the electrochemical properties of NCM613@0.3%WY under harsh conditions, NCM613 and NCM613@0.3%WY were subjected to cyclic testing at 60℃, 1C, and 2.8-4.3V. High temperatures exacerbated interfacial side reactions and structural degradation. Figure 6 The results showed that NCM613@0.3%WY exhibited better cycling performance, with the discharge capacity increasing from 148.0 mAh·g. -1 Decayed to 97.85 mAh·g -1After 100 cycles, the capacity retention rate was 66.1%, while the capacity of NCM613 decreased from 145.2 mAh·g. -1 Decayed to 22.3 mAh·g -1 The capacity retention rate was only 16.0%, indicating that the NCM613@0.3%WY coated with WY exhibited significantly better cycling performance under high temperature testing than the uncoated material. This result effectively demonstrates that the WY composite coating layer can still provide interfacial protection and bulk stability at high temperatures.
[0048] To further investigate the electrochemical performance, experiments were conducted at 2.8–4.3 V and 0.1 mV·s. −1 Under these conditions, NCM613 and NCM613@0.3%WY were tested using cyclic voltammetry (CV). Figure 7 As shown, the image clearly reveals a pair of major redox peaks for this material in the voltage range of approximately 3.75 V to 4.1 V, corresponding to Ni. 2+ / Ni 4+ The electrochemical reaction was observed. From the first to the third cycle, the ∆V of NCM613 in the first cycle (0.21797V) was slightly higher than that of NCM613@0.3%WY (∆V=0.1923V). In the third cycle, the ∆V of NCM613 (0.182V) was still higher than that of NCM613@0.3%WY, indicating that WY coating can reduce the polarization in the electrochemical reaction and suppress harmful side reactions at the electrode / electrolyte interface.
[0049] Table 2 Electrochemical performance test results of different samples
[0050] Sample <![CDATA[Initial discharge capacity at 0.1C, mAh·g -1 > Coulomb efficiency <![CDATA[Discharge capacity at 5C high rate mAh·g -1 > Cycle 120 times at 0.2°C / 25°C. 100 cycles at 1°C / 60°C NCM613 164.3 81.9% 23.2 67.9% 16.0% NCM613@0.3%W 165.9 84.3% 93 69.6% 31.2% NCM613@0.3%WY 174.9 84.46% 95 70.3% 66.1% NCM613@1%WY 166.4 84.2% 91 68.2% 68.3% NCM613@0.1%WY 165.1 83.7% 62 68.1% 33.6%
[0051] Therefore, this invention successfully prepared WY composite-coated modified NCM613 cathode material using a high-temperature solid-state method. The results show that the WY composite coating effectively improves the electrochemical performance and structural stability of the material while maintaining its layered structure. Among them, the NCM613@0.3%WY sample exhibited the best overall performance: its first-cycle discharge specific capacity reached 174.9 mAh·g. -1 (Uncoated sample 164.3 mAh·g) -1 The coulombic efficiency is 84.46%; the discharge capacity at a high rate of 5C is 95 mAh·g. -1 The concentration was significantly higher than that of the uncoated sample (23.2 mAh·g). -1 In both room temperature and high temperature cycling tests, the sample exhibited the highest capacity retention and the slowest voltage decay. The smaller redox peak potential difference (ΔV) in the CV test further confirmed that the composite coating effectively reduced polarization and suppressed interfacial side reactions, providing an effective strategy for the multi-element synergistic coating modification of high-nickel ternary materials.
[0052] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A method for preparing a WY composite-coated NCM613 cathode material, characterized in that, Includes the following steps: (1) Mix nano-tungstic acid and yttrium oxide in a predetermined ratio to obtain the WY composite precursor; (2) Mix the NCM613 active material with the WY composite precursor obtained in step (1) according to a set ratio, and after thorough grinding, obtain a uniform mixture; (3) Place the mixture obtained in step (2) in a tube furnace and sinter it at 600~800℃ for 1~4 hours under an inert atmosphere. Then grind the sintered product after cooling in the furnace to obtain WY composite coated NCM613 cathode material.
2. The method for preparing a WY composite-coated NCM613 cathode material according to claim 1, characterized in that, In step (1), nano-tungstic acid and yttrium oxide are added to a planetary ball mill at a W:Y molar ratio of 1:0.05~0.25 and ball-milled at a speed of 200~1000 rpm for 2~24 hours.
3. The method for preparing a WY composite-coated NCM613 cathode material according to claim 1, characterized in that, In step (2), the NCM613 active substance and the WY composite precursor obtained in step (1) are mixed in a molar ratio of 1:0.001~0.
01.
4. The method for preparing a WY composite-coated NCM613 cathode material according to claim 1, characterized in that, In step (3), the temperature is raised to 700°C and sintered for 2 hours under the protection of argon atmosphere.
5. A WY composite-coated NCM613 cathode material, characterized in that, It is prepared by any one of the methods described in claims 1 to 4.
6. The application of the WY composite-coated NCM613 cathode material according to claim 5 in lithium-ion batteries.