Modified high-nickel positive electrode material, and preparation method therefor and use thereof

Abstract

The present application relates to the technical field of new energy, and discloses a modified high-nickel positive electrode material, and a preparation method therefor and a use thereof. The modified high-nickel positive electrode material provided by the present application comprises a porous matrix material having a general chemical formula of LiNixMyM'zO2, and an interstitial filler substance, wherein 0.80≤x≤0.98, 0<y≤0.20, 0<z≤0.02, x+y+z=1, M is at least two of Co, Mn, and Al, and M' is at least two of Zr, Sr, Ca, Mg, Ba, Y, Nb, Ti, Mo, Sn, Ta, Sb, Bi, and W. The interstitial filler substance is located inside pores in the matrix material and comprises a sinter derived from an additive B, and the additive B comprises boron nitride and a calcium-containing compound. The modified high-nickel positive electrode material provided by the present application has excellent pressure resistance and cycle structure stability. The present application further provides a preparation method for and a use of the modified high-nickel positive electrode material.

Description

Modified high-nickel positive electrode material, preparation method and application thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy, in particular to a modified high-nickel positive electrode material, a preparation method and application thereof. BACKGROUND

[0002] The layered metal oxide positive electrode material has formed a relatively systematic and mature system according to different elements and component ratios. The material system of nickel-cobalt-manganese or nickel-cobalt-aluminum can be collectively referred to as a ternary material. When the molar amount of nickel accounts for more than 80% of the molar amount of transition metals in the layered metal oxide positive electrode material, it is referred to as a high-nickel material. The high-nickel material has advantages such as high capacity, high specific energy, stable performance and low cost, and is therefore considered to be an attractive choice in the field of power batteries and other fields, and is also a widely used and deeply researched positive electrode material. With the further improvement of energy density requirements, the application of high-nickel or even super-high-nickel materials has become a more explicit and urgent need. It is inevitable that more technical difficulties need to be overcome to achieve effective application. For example, the synthesis conditions of the material are increasingly harsh, the structural stability is poor, and the safety is decreased, and so on.

[0003] At the same time, new process technologies for battery applications have gradually emerged, such as blade batteries, tab-free technology, and so on. People have gradually put forward higher requirements in the process of applying positive electrode materials, such as the pursuit of the limit of the useable compaction density, the prediction and prevention of failure mechanisms during use, and so on. Therefore, for high-nickel positive electrode materials, in addition to solving the technical and cost problems of synthesizing materials, the processing performance of the material, such as the hygroscopicity and pressure resistance of the material, also needs to be considered. Furthermore, the compatibility of the material volume change and the continuous occurrence of side reactions during battery cycling needs to be further improved, so that these characteristics can be recognized and even accepted.

[0004] In order to realize the high specific energy application of high-nickel positive electrode powder material, the powder material needs to go through a high compaction process during the production of electrode sheets, and needs to go through a continuous particle embedding and de-embedding expansion and contraction process during the battery cycling process. Therefore, the improvement of the pressure resistance and material strength of high-nickel / super-high-nickel materials plays a crucial role in the application of high-nickel / super-high-nickel materials, and plays a crucial role in the technical development of high specific energy batteries.

[0005] The performance improvement of the current high-nickel material mainly focuses on the improvement of electrochemical performance and process improvement and cost reduction. On the one hand, developers improve the capacity release and stability of the material by means of component and size adjustment, doping and coating modification, sintering and post-treatment optimization, etc. On the other hand, the performance is improved by controlling and optimizing the equipment and parameters of the processes such as mixing, sintering, washing and crushing.

[0006] With the increase of nickel content, the pressure resistance and cracking problem of high-nickel material becomes more and more serious due to the increase of lattice structure instability and the weakening of nickel-cobalt-manganese synergistic effect.

[0007] At present, there is still no in-depth research and systematic solution to the problems of insufficient particle strength in the production process of high-nickel positive electrode material and cracking during the cycle process. The few research works on the improvement of the insufficient strength and cracking of high-nickel positive electrode material focus on the strengthening modification of the material grain boundary by introducing oxides or fluorides, etc. The effect cannot be defined, and the improvement is mainly the auxiliary effect of other performance improvement. The conclusion is speculative, and there is no special modification work of strength and cracking and no effective proof. SUMMARY

[0008] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides a modified high-nickel positive electrode material, which can effectively improve the pressure resistance of the obtained high-nickel positive electrode material and significantly improve the powder strength and structural stability thereof.

[0009] The present application also provides a preparation method of the modified high-nickel positive electrode material.

[0010] The present application also provides an application of the modified high-nickel positive electrode material.

[0011] According to the embodiment of the first aspect of the present application, a modified high-nickel positive electrode material is provided, which comprises:

[0012] a base material, the chemical formula of the base material is LiNi x M y M’ zO2; wherein, 0.80≤x≤0.98, preferably 0.80≤x≤0.95, 0

[0013] a gap-filling substance, the gap-filling substance being present inside the pores; the gap-filling substance comprising a sintered product derived from the additive B,

[0014] the additive B comprises boron nitride and a calcium-containing compound.

[0015] The modified high-nickel positive electrode material provided in the present application has stable structure of the base material due to the combination of materials, and can improve the compression resistance to a certain extent.

[0016] Further, in the additive B, the boron nitride is a lubricating substance, which is beneficial to the gap filling of the base material and can improve the compression resistance.

[0017] Further, in the additive B, the Ca ions in the calcium-containing compound can adhere to the polyatomic ions (SO4 - roots, residues of the preparation of the precursor, etc., thereby improving the bonding strength between the gap-filling substance and the base material and further improving the mechanical strength of the obtained modified high-nickel positive electrode material.

[0018] By using the combination of the above-mentioned boron nitride and calcium-containing compound, the synergistic effect of lubrication and gap filling and adhesion is achieved, and the compression resistance and particle strength of the material of the present application are unexpectedly improved.

[0019] Overall, in the obtained modified high-nickel positive electrode material, the internal porosity can be significantly reduced, and the mechanical properties such as compression resistance and crack resistance can be improved by limiting the material and structure, and finally the particle cracking ratio and cracking width of the obtained modified high-nickel positive electrode material in the long cycle or high rate electrochemical process are significantly reduced.

[0020] According to some embodiments of the present application, in the base material, 0.80≤x≤0.98, preferably 0.80≤x≤0.96, and further preferably 0.80≤x≤0.95. For example, it can be specifically 0.80, 0.85, 0.90, 0.91, 0.92, 0.93, 0.94 or 0.95.

[0021] According to some embodiments of the present application, in the base material, M is a combination of Co and Mn. The molar ratio of Co to Mn is 1.5-2.5:1. For example, it can be specifically 1.6:1, 1.7:1, 1.8:1, 1.9:1, or about 2:1, etc.

[0022] According to some embodiments of the present application, in the base material, y can be 0.01≤y≤0.20, preferably 0.02≤y≤0.20, more preferably 0.04≤y≤0.20, and further preferably 0.045≤y≤0.20. For example, it can be specifically about 0.02, 0.03, 0.04, 0.045, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, or about 0.20.

[0023] According to some embodiments of the present application, in the base material, z can be 0.002≤z≤0.02, preferably 0.005≤z≤0.018. For example, it can be specifically about 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.015, or about 0.018.

[0024] According to some embodiments of the present application, in the base material, M' includes at least two of Zr, Sr, Y, Nb, Ca, Ti, Sb, and W, and is not particularly limited as long as it can play a certain doping role. Preferably, M' includes at least two of Zr, Sr, Y, Nb, Ti, Sb, and W. Further specifically, M' includes at least two or at least one of Zr, Sr, Y, Nb, and W.

[0025] According to some embodiments of the present application, in the base material, M' is selected from a combination of Zr, Sr, Y, and W, or a combination of Zr, Sr, Nb, and W. In M', the mole percentage of Zr is 50% to 60%. For example, it can be specifically 54%, 55%, or 56%, etc., and can also be an end value, the same below. The mole percentage of Sr is 10% to 20%. For example, it can be specifically 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, or 19%, and can also be an end value, the same below. The mole percentage of Y or Nb is 5% to 10%. For example, it can be specifically 6%, 7%, 8%, or 9%. The mole percentage of W is 15% to 30%. For example, it can be specifically 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%.

[0026] According to some embodiments of the present application, the base material has a divergent structure. Specifically, the base material is a secondary particle formed by arrangement and stacking of primary particles.

[0027] According to some embodiments of the present application, the calcium-containing compound includes at least one of calcium carbonate, calcium hydroxide, calcium phosphate and calcium pyrophosphate.

[0028] According to some embodiments of the present application, the concentration of the element B derived from the additive B in the modified high-nickel positive electrode material is 200 ppm to 5000 ppm, preferably 250 ppm to 4800 ppm. For example, it can be specifically about 300 ppm, 500 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 2000 ppm, 3000 ppm, 4000 ppm, 4500 ppm, 4700 ppm, 4800 ppm or about 4900 ppm.

[0029] According to some embodiments of the present application, the concentration of the element Ca derived from the additive B in the modified high-nickel positive electrode material is 100 ppm to 2000 ppm, preferably 150 ppm to 1800 ppm. For example, it can be specifically about 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1500 ppm, 1700 ppm, 1800 ppm or about 1900 ppm.

[0030] According to some embodiments of the present application, the structure of the boron nitride in the additive B includes at least one of nanowires and nanosheets. Further, the average equivalent particle size of the boron nitride is 25 nm to 35 nm. For example, it can be specifically about 30 nm.

[0031] According to some embodiments of the present application, the modified high-nickel positive electrode material further has a coating layer, and the coating layer contains a sintered product derived from an additive C.

[0032] According to some embodiments of the present application, the coating layer is wrapped on the surface of the modified high-nickel positive electrode material.

[0033] The additive C includes at least one of boric acid, aluminum oxide, aluminum hydroxide, cerium oxide, aluminum fluoride, cerium fluoride, magnesium oxide, magnesium hydroxide.

[0034] Through the setting of the coating layer and the combination of the additive C, the capacity of the obtained modified high-nickel positive electrode material can be significantly improved.

[0035] According to some embodiments of this application, the additive C comprises boric acid, and at least one selected from aluminum oxide, aluminum hydroxide, cerium oxide, aluminum fluoride, cerium fluoride, magnesium oxide, and magnesium hydroxide. Preferably, the additive C comprises boric acid, and at least one selected from cerium fluoride, magnesium oxide, and aluminum fluoride. The mass ratio of boric acid to other substances in additive C is 0.025-5:1, preferably 0.1-4:1. For example, it can be 0.1:1, 0.2:1, 0.5:1, 1:1, 1.5:1, 2:1, 3:1, or 4:1, etc.

[0036] According to some embodiments of this application, the additive C is 0.3% to 3% by mass relative to the primary sintering product, preferably 0.5% to 2%. In actual production, the additive C is close to the mass of the coating layer, or it can be determined according to the mass percentage of the coating layer in the modified high-nickel cathode material.

[0037] According to some embodiments of this application, the modified high-nickel cathode material actually possesses a core-shell structure, wherein:

[0038] The core includes a matrix material and a filling material disposed inside the pores of the matrix material;

[0039] The shell is a coating layer that surrounds the surface of the core and contains a sintered material derived from additive C.

[0040] According to some embodiments of this application, the coating layer accounts for 0.1% to 4% of the mass percentage of the modified high-nickel cathode material, preferably 0.5% to 3.5%, and more preferably 0.5% to 2.0%. Specifically, it can be about 0.5%, 1.0%, 1.5%, 2.0%, 3.0%, or about 3.5%.

[0041] According to some embodiments of this application, the breakdown point P of the modified high-nickel cathode material is... τ The pressure ranges from 40 MPa to 65 MPa. This collapse point refers to the point at which the compacted density breaks down as the pressure increases under continuously varying pressure.

[0042] According to some embodiments of this application, the breakdown point P of the modified high-nickel cathode material is... τ The pressure is 45 MPa to 62 MPa, preferably 49 MPa to 62 MPa. More specifically, it can be about 46 MPa, 50 MPa, 51 MPa, 52 MPa, 53 MPa, 54 MPa, 55 MPa, 56 MPa, 57 MPa, 58 MPa, 59 MPa, 60 MPa or about 61 MPa.

[0043] The modified high-nickel positive electrode material provided in the application has a collapse point that is 10% higher than the collapse point of the existing high-nickel positive electrode material with the same nickel content. In actual production, the improvement can reach 20%, or even 40% or more than about 80%.

[0044] According to some embodiments of the application, the porosity inside the modified high-nickel positive electrode material is ≤3%. In the application, porosity refers to the percentage of blank area in the total area of the particle in the cross-sectional SEM image. Generally, the cross-sectional SEM images of multiple modified high-nickel positive electrode materials need to be counted.

[0045] According to some embodiments of the application, the porosity inside the modified high-nickel positive electrode material is 0.1% to 3.0%, preferably 0.1% to 2.0%, more preferably 0.1% to 1.0%, further preferably 0.25% to 0.8%, and more preferably 0.25% to 0.57%. Specifically, it can be about 0.1%, 0.15%, 0.2%, 0.25%, 0.28%, 0.3%, 0.31%, 0.32%, 0.33%, 0.35%, 0.4%, 0.5%, 0.6%, 0.55%, 1.0%, 1.1%, 1.2%, 1.3%, or about 1.5%.

[0046] According to some embodiments of the application, in the modified high-nickel positive electrode material, there are divergent structures and composite interstitial structures, that is, the primary particles are divergent from inside to outside, the regularity is better, the uniformity of the interstitial distribution between the primary particles is improved, the interstitial pores are generally reduced, and the interstitial pores are filled with specific interstitial substances. After the cycle test of the button cell, the particle cross-sectional image of the modified high-nickel positive electrode material is observed from the electrode sheet, and the results show that, compared with the conventional high-nickel positive electrode material, the cracking degree is improved, and the number of cracks and the cracking width are significantly reduced.

[0047] According to the embodiments of the second aspect of the application, a preparation method of a modified high-nickel positive electrode material is provided. The modified high-nickel positive electrode material in the preparation method can be the modified high-nickel positive electrode material containing the matrix material and the interstitial substance described above. The preparation method comprises mixing a precursor Ni a M b (OH)2, a lithium source, an additive A, and an additive B in an oxygen-containing environment to obtain a primary sintered product;

[0048] The primary sintered product contains the matrix material and the interstitial substance. The transition metal elements such as Ni, Co, and Mn come from the precursor and the additive A, M' comes from the additive A, and the interstitial substance comes from the additive B;

[0049] The precursor Ni a M b(OH)2, 0.80≤a≤0.98, specifically can be 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97 or 0.98, 0

[0050] The additive A is at least two of oxides, hydroxides or carbonates of Zr, Sr, Ca, Mg, Ba, Y, Nb, Ti, Mo, Sn, Ta, Sb, Bi and W;

[0051] The additive B comprises boron nitride and a calcium-containing compound;

[0052] The primary sintering comprises a first holding platform and a second holding platform; the temperature of the first holding platform is 350-650°C; the temperature of the second holding platform is 680-900°C.

[0053] In the preparation method provided in the application, lithium salt, suitable additive A and additive B are added in the primary sintering process, and specific temperatures of the first holding platform and the second holding platform are limited; thus, the additive A plays a doping role, and a small amount of additive A that is not doped into the crystal lattice can exist in the gaps and surface of the modified high-nickel positive electrode material; the additive B plays a role of filling the gaps, and a small amount of additive B can participate in preliminary doping and surface coating, and a small amount of sintered additive B can exist on the surface of the base material, but does not affect the performance. The second holding platform is beneficial to the remodeling and growth of the crystal and effectively releases the internal stress of the crystal.

[0054] Specifically, the limitation of the temperature of the first holding platform allows the lithium source and the additive A to achieve the best melting effect and reactivity, and is more conducive to the lithium salt and the additive A to infiltrate into the gaps of the precursor, and further, the additive A in the gaps, in which the element M' and Li in the lithium salt penetrate into the interior of the primary particles and form part of the crystal lattice, to obtain a sintered material with modified grain morphology; the first holding platform can also significantly improve the temperature uniformity of the mixture to be sintered and achieve sufficient oxygen concentration of the microenvironment atmosphere by sufficient exhaust for a certain time. The second holding platform is mainly considered from the perspective of thermodynamic reaction conditions, and the temperature of the platform is kept constant for a period of time, which is beneficial to the full development of the crystal and the release of surface stress, to form a material with complete crystal form and stable surface structure.

[0055] The lithium salt and the precursor also have the function of flux, which can reduce the melting / decomposition temperature of the additive B to some extent, decompose it into smaller particles, and fully play the role of filling gaps. At the same time, the additive B itself has the function of sintering aid, for example, compared with lithium, the Ca element in the calcium-containing compound can combine with S anion during sintering process, improve the utilization rate of lithium, and also can reduce the reaction energy barrier and modify the crystal surface and grain boundary, and can promote the sintering product of the additive B to "adhere to the combination" with the matrix material, and improve the filling effect; when the additive B contains boron nitride, the N-B bond in the boron nitride is very strong, the substance is very stable, and the melting point is about 3100 degrees. It can be used as lubricating and interface stabilizing substance. In addition, the additive B has a high melting / decomposition temperature, and the high temperature of the second holding platform can promote it to decompose into smaller size, and then achieve the effect of filling the gap. Overall, by using the synergistic effect of the two substances in the additive B and by setting two holding platforms, the additive B can fully play the role of filling the gap.

[0056] According to the preparation method of the embodiments of the present application, the particle strength of the obtained modified high-nickel positive electrode material is unexpectedly and significantly improved, and finally the pressure resistance of the modified high-nickel positive electrode material is improved.

[0057] By testing the pressurization process of the powder particles, the collapse point P τ is obtained. The results show that, compared with the traditional high-nickel positive electrode material, the P τ of the modified high-nickel positive electrode material prepared by the present application is greatly improved; moreover, after the modified high-nickel positive electrode material provided by the present application is cycled under the same conditions, the scanning electron microscope test shows that the cracking condition is obviously improved.

[0058] According to some embodiments of the present application, the preparation method of the modified high-nickel positive electrode material in the embodiments of the second aspect of the present application can obtain the modified high-nickel positive electrode material in the embodiments of the first aspect of the present application.

[0059] According to some embodiments of the present application, in the precursor Ni a M b (OH)2, the value range of a is 0.8 to 0.956. For example, it can be about 0.81, 0.85, 0.88, 0.9, 0.91, 0.92, 0.93 or about 0.95.

[0060] According to some embodiments of the present application, in the precursor Ni a M bThe value of b ranges from 0.02 to 0.2, preferably from 0.08 to 0.2. For example, it can be about 0.02, 0.03, 0.04, 0.045, 0.05, 0.06, 0.08, 0.1, 0.11, 0.12, 0.15 or about 0.2.

[0061] According to some embodiments of the present application, the porosity of the precursor is 2% to 15%, preferably 3% to 10%, more preferably 3% to 5%, and can be about 3%, 3.2%, 3.8%, 4%, 4.2%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or about 10%. The porosity of the precursor is greater than that of the modified high-nickel positive electrode material, because on the one hand the precursor is subjected to the primary sintering, secondary sintering and the like, which leads to a decrease in porosity, and on the other hand the additive B has a gap-filling effect, which ultimately significantly reduces the porosity.

[0062] According to some embodiments of the present application, the particle size D50 of the precursor is 2 μm to 20 μm, preferably 4 μm to 15 μm, and more preferably 10 μm, 11 μm, 11.5 μm, 12 μm or about 12.5 μm.

[0063] According to some embodiments of the present application, the precursor is self-made or commercially available. Whether self-made or commercially available, the crystal growth is carried out in stages, and the ratio of the flow rate / solid content of the mixed metal salt in different crystal growth stages is controlled, so that the crystal grows rapidly in the system, and finally a high-porosity precursor with good sphericity, narrow distribution and a radial outward appearance is obtained. The high-porosity precursor is beneficial to the mixing process of the primary sintering, the infiltration of the additive A, and the filling of the additive B into the pores of the precursor, which helps to build a composite pressure-resistant structure of the primary particles and the secondary spherical surface, significantly improves the strength of the powder and improves the structural stability, and obtains a modified high-nickel positive electrode material with excellent compression and cracking resistance.

[0064] According to some embodiments of the present application, the additive A includes at least two of the oxides, hydroxides or carbonates of Zr, Sr, Y and W.

[0065] According to some embodiments of the present application, the additive A includes at least two of the oxides, hydroxides or carbonates of Zr, Sr, Nb and W.

[0066] In actual production, the type and amount of the additive A are determined according to the chemical formula of the target base material, which is a routine operation. In another aspect, the chemical composition formula of the base material can be calculated from the raw materials and their charging amounts.

[0067] According to some embodiments of the present application, the lithium source comprises lithium carbonate and / or lithium hydroxide, preferably lithium hydroxide.

[0068] According to some embodiments of the present application, the molar ratio of lithium element in the lithium source to the precursor is 1-1.05:1, preferably 1.02-1.04:1. For example, it can be specifically 1:1, 1.01:1, 1.02:1, 1.03:1, 1.04:1 or 1.05:1, etc.

[0069] According to some embodiments of the present application, the temperature of the first holding platform is 350-650°C, preferably 400-600°C, and further preferably 450-600°C. For example, it can be specifically about 420°C, 450°C, 480°C, 500°C or 600°C, etc.

[0070] According to some embodiments of the present application, the holding time of the first holding platform is 2-6h. For example, it can be specifically about 3h, 4h or about 5h.

[0071] According to some embodiments of the present application, the temperature of the second holding platform is 680-850°C, preferably 710-830°C. For example, it can be specifically about 700°C, 710°C, 750°C, 780°C, 800°C or 830°C, etc.

[0072] According to some embodiments of the present application, the holding time of the second holding platform is 6-16h. For example, it can be specifically about 10h, 12h, 14h or 15h, etc.

[0073] According to some embodiments of the present application, in the primary sintering, the first holding platform is performed first, and then the second holding platform is performed. After the primary sintering, the temperature is lowered to room temperature, which can be lowered naturally, and after the temperature is lowered, crushing can be performed.

[0074] In actual production, the amount of additive B added in production is appropriately determined according to various specific conditions such as the concentration or porosity of the modified high-nickel positive electrode material.

[0075] According to some embodiments of the present application, the preparation method further comprises washing the product of the primary sintering with water, and mixing the water-washed product with additive C and then performing secondary sintering;

[0076] The additive C comprises at least one of boric acid, aluminum oxide, aluminum hydroxide, cerium oxide, aluminum fluoride, cerium fluoride, magnesium oxide, and magnesium hydroxide.

[0077] According to some embodiments of the present application, the mass ratio of the water used in the water washing to the mass of the product of the primary sintering is 0.4-2.0:1, preferably 0.5-1.5:1. For example, it can be about 0.5:1, 1:1 or about 1.5:1. In this way, residual alkali can be effectively removed, and the processing performance of the modified high-nickel positive electrode material is improved.

[0078] According to some embodiments of the present application, the temperature of the water washing is 5-30°C, preferably 10-25°C. For example, it can be about 10°C, 15°C, 20°C or about 25°C, or the end value as above. In actual production, it can be selected and adjusted as needed; the present application does not make strict limitations.

[0079] According to some embodiments of the present application, the duration of the water washing is 3-50 min, preferably 5-45 min. For example, it can be about 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 40 min or about 45 min. The duration of the water washing is the time consumed between the product of the primary sintering being completely soaked by water and the completion of the solid-liquid separation. The method of the solid-liquid separation includes at least one of filtration and centrifugation.

[0080] According to some embodiments of the present application, the preparation method further comprises drying the obtained water washing product after the water washing.

[0081] According to some embodiments of the present application, the temperature of the drying is 100-160°C. For example, it can be about 100°C, 110°C, 120°C, 130°C, 140°C, 150°C or about 160°C, preferably 100-130°C.

[0082] According to some embodiments of the present application, the constant temperature of the secondary sintering is 200-400°C, preferably 250-350°C. For example, it can be about 250°C, 300°C or about 350°C.

[0083] According to some embodiments of the present application, the duration of the secondary sintering is 5-10 h, preferably 6-8 h.

[0084] According to some embodiments of the present application, the preparation method comprises the following steps:

[0085] S1. In an oxygen-containing environment, mixing the precursor Ni(OH)2, the lithium source, the additive A and the additive B, and performing primary sintering; a M b (OH)2, a lithium source, an additive A and an additive B, and performing primary sintering;

[0086] S2. Water washing the product of the primary sintering and drying;

[0087] S3. The product obtained in step S2 is mixed with additive C and then subjected to secondary sintering.

[0088] According to the embodiments of the third aspect of the present application, a lithium secondary battery is provided, raw materials for preparing the lithium secondary battery comprising the modified high-nickel positive electrode material or the modified high-nickel positive electrode material prepared by the preparation method.

[0089] Since the lithium secondary battery adopts all the technical solutions of the modified high-nickel positive electrode material of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments. That is, the lithium secondary battery has excellent volume energy density and excellent cycle performance.

[0090] According to some embodiments of the present application, the lithium secondary battery comprises at least one of a button cell, a soft pack cell, a prismatic cell, and a cylindrical cell.

[0091] According to some embodiments of the present application, the lithium secondary battery comprises at least one of a symmetric cell, a half cell, and a full cell.

[0092] According to some embodiments of the present application, the capacity retention rate of the lithium secondary battery after 50 cycles at 1C is ≥91%. For example, it can be specifically 91%, 92%, 93%, 94%, 95%, 96%, or about 97%.

[0093] Unless otherwise specified, "about" in the present application actually means that the allowed error is within ±2%, for example, about 100 actually means 100 ± 2% × 100.

[0094] Unless otherwise specified, "between" in the present application includes the numbers, for example, "between 2 and 3" includes the end values 2 and 3.

[0095] Other features and advantages of the present application will be set forth in the specification, and in part will become apparent from the specification, or can be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0096] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which:

[0097] FIG. 1 is a cross-sectional SEM image of the modified high-nickel positive electrode material obtained in Example 1 of the present application.

[0098] FIG. 2 is a cross-sectional SEM image of the modified high-nickel positive electrode material obtained in Comparative Example 1 of the present application.

[0099] FIG. 3 is a pressure resistance performance graph of the modified high-nickel positive electrode materials obtained in Example 1 and Comparative Example 1 of the present application.

[0100] Figure 4 is a cross-sectional SEM image of the modified high-nickel positive electrode material obtained in Example 1 of the present application after cycling.

[0101] Figure 5 is a cross-sectional SEM image of the modified high-nickel positive electrode material obtained in Comparative Example 1 of the present application after cycling.

[0102] Figure 6 is a cycle performance graph of Example 1 and Comparative Example 1 of the present application.

[0103] Figure 7 is an EDS spectrum of the high-nickel positive electrode material obtained in Example 1 (a-b) and Comparative Example 1 (c-d) of the present application.

[0104] Figure 8 is a surface SEM image of the modified high-nickel positive electrode material obtained in Example 1 of the present application.

[0105] Figure 9 is a surface SEM image of the high-nickel positive electrode material obtained in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0106] The concept and the technical effects of the present application will be described in detail below in conjunction with the embodiments, so as to fully understand the purpose, features and effects of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0107] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0108] Example 1

[0109] Step S1

[0110] In an oxygen concentration environment of 90%, the chemical formula of the target base material is LiNi 0.90 Co 0.05 Mn 0.03 M’ 0.02 O2, wherein M’ = Zr 0.012 Sr 0.004 Y 0.001 W 0.003 , the feeding amount is calculated, and the precursor Ni a M bThe lithium hydroxide monohydrate, the additive A and the additive B are mixed, and then one-time sintering is performed, the one-time sintering product is obtained after crushing after temperature reduction.

[0111] The one-time sintering product contains a matrix material and a gap material.

[0112] The chemical formula of the matrix material is LiNi 0.90 Co 0.05 Mn 0.03 M’ 0.02 In LiNiCoMnO2, the transition metal elements Ni, Co and Mn come from the precursor, the doping element M’ comes from the additive A, and the gap material comes from the additive B.

[0113] The chemical formula of the precursor Ni a M b (OH)2 is Ni 0.918 Co 0.051 Mn 0.031 (OH)2; the D50 particle size is about 11.5 μm; and the porosity is about 3.8%.

[0114] The molar ratio of lithium in the lithium salt to the precursor is 1.03:1.

[0115] The additive A is a mixture of zirconium oxide, strontium oxide, yttrium oxide and tungsten trioxide, and the mixing ratio is calculated according to the composition of M’.

[0116] The additive B is a mixture of boron nitride (flaky, average equivalent particle size is about 30 nm) and calcium hydroxide, and the addition amount is calculated according to the concentration of B element and Ca element in the product obtained in this step shown in Table 1.

[0117] The one-time sintering includes a first holding platform and a second holding platform in sequence; after being heated to the first holding platform at 2℃ per minute, holding is performed, and then after being heated to the second holding platform at 2℃ per minute, holding is performed again, wherein the constant temperature of the first holding platform is 450℃; the time length is 3h, and the constant temperature of the second holding platform is 750℃; the time length is 12h.

[0118] Step S2

[0119] The one-time sintering product obtained in step S1 is washed with pure water, wherein the mass ratio of the pure water to the one-time sintering product is 1:1, the water washing temperature is 15℃, and the time length is 20min; and then drying is performed at 120℃.

[0120] Step S3

[0121] The product obtained in step S2 is mixed with the additive C, and secondary sintering is performed at 310℃ for 7h. The product is sieved through a 325 mesh screen to obtain the modified high-nickel positive electrode material of the present application, and the porosity is shown in Table 2.

[0122] In which, as shown in Table 1, the additive C includes boric acid and cerium fluoride, the mass ratio of boric acid to cerium fluoride is 3:1, and the addition amount is 1.5% relative to the mass percentage of the primary sintered product.

[0123] Example 2

[0124] Step S1

[0125] In an oxygen concentration environment of 90%, the chemical formula of the target base material is LiNi 0.8 Co 0.12 Mn 0.078 M’ 0.002 O2, wherein M’ = Zr 0.001 Sr 0.0002 Y 0.0002 W 0.0006 , the feed amount is calculated, the precursor Ni s M b (OH)2, lithium hydroxide monohydrate, additive A and additive B are mixed, and then primary sintering is performed, and after cooling, the primary sintered product is obtained by crushing;

[0126] In which, the primary sintered product contains base material and interstitial substance;

[0127] The chemical formula of the above base material is LiNi 0.8 Co 0.12 Mn 0.078 M’ 0.002 O2, wherein the transition metal elements Ni, Co and Mn come from the precursor, the doping element M’ comes from the additive A, and the interstitial substance comes from the additive B;

[0128] The chemical formula of the precursor Ni a M b (OH)2 is Ni 0.802 Co 0.12 Mn 0.078 (OH)2; the D50 particle size is about 12.5 μm; and the porosity is about 3.2%.

[0129] The molar ratio of lithium element in the lithium salt to the precursor is 1.04:1;

[0130] The additive A is a mixture of zirconium oxide, strontium oxide, yttrium oxide and tungsten trioxide, and the mixing ratio is calculated according to the composition of M’;

[0131] The additive B is a mixture of boron nitride (flaky, average equivalent particle size of about 30 nm) and calcium hydroxide, and the addition amount is calculated according to the concentration of B element and Ca element in the product obtained in this step shown in Table 1;

[0132] A single sintering process includes a first holding platform and a second holding platform, which are carried out sequentially. The temperature is increased to the first holding platform at 2°C per minute and then held at that temperature. The temperature is then increased to the second holding platform at 2°C per minute and held at that temperature again. The constant temperature of the first holding platform is 600°C and the holding time is 2 hours. The constant temperature of the second holding platform is 830°C and the holding time is 6 hours.

[0133] Step S2

[0134] The primary sintering product obtained in step S1 is washed with pure water, wherein the mass ratio of pure water to primary sintering product is 1.5:1, the washing temperature is 25℃, and the washing time is 15min; then it is dried at 130℃.

[0135] Step S3

[0136] The product obtained in step S2 was mixed with additive C and subjected to secondary sintering at 350°C for 6 hours. The mixture was then passed through a 325-mesh sieve to obtain the modified high-nickel cathode material of this application.

[0137] As shown in Table 1, additive C includes boric acid and cerium fluoride, with a mass ratio of boric acid to cerium fluoride of 0.5:1, and the amount added is 0.5% of the mass percentage of the primary sintering product.

[0138] Example 3

[0139] Step S1

[0140] In an environment with a 90% oxygen concentration, according to the target matrix material with the chemical formula LiNi 0.948 Co 0.029 Mn 0.015 M' 0.008 O2, where M' = Zr 0.0044 Sr 0.00116 Nb 0.00064 W 0.0018 Calculate the feed amount and add the precursor Ni a M b (OH)2, lithium hydroxide monohydrate, additive A and additive B are mixed, and then sintered once. After cooling, the mixture is crushed to obtain the sintered product.

[0141] The primary sintering product contains matrix material and interstitial material;

[0142] The chemical formula of the above matrix material is LiNi. 0.948 Co 0.029 Mn 0.015 M' 0.008 In O2, the transition metal elements Ni, Co, and Mn come from the precursor, the dopant element M' comes from additive A, and the interstitial material comes from additive B.

[0143] Precursor Ni a M b (OH)2, and the chemical formula of the precursor Ni 0.956 Co 0.029 Mn 0.015 (OH)2; the D50 particle size is about 11.0 μm; and the porosity is about 4.2%.

[0144] The molar ratio of lithium element in the lithium salt to the precursor is 1.02:1;

[0145] The additive A is a mixture of zirconium oxide, strontium oxide, niobium oxide and tungsten trioxide, and the mixing ratio is calculated according to the composition of M';

[0146] The additive B is a mixture of boron nitride (flaky, with an average equivalent particle size of about 30 nm) and calcium hydroxide, and the addition amount is calculated according to the concentrations of B element and Ca element in the product obtained in this step shown in Table 1;

[0147] The primary sintering includes a first holding platform and a second holding platform in sequence; after heating to the first holding platform at 2℃ per minute, holding is performed, and then after heating to the second holding platform at 2℃ per minute, holding is performed again, wherein the constant temperature of the first holding platform is 480℃; the time length is 6h, and the constant temperature of the second holding platform is 710℃; the time length is 15h.

[0148] Step S2

[0149] The primary sintering product obtained in step S1 is washed with pure water, wherein the mass ratio of pure water to the primary sintering product is 0.5:1, the water washing temperature is 10℃, and the time length is 30min; and then drying is performed at 100℃.

[0150] Step S3

[0151] The product obtained in step S2 is mixed with the additive C, and secondary sintering is performed at 250℃ for 8h; and then sieving is performed through a 325 mesh screen to obtain the modified high-nickel positive electrode material of the application.

[0152] As shown in Table 1, the additive C includes boric acid and cerium fluoride, the mass ratio of boric acid to cerium fluoride is 4:1, and the addition amount is 2.0% relative to the mass of the primary sintering product.

[0153] Example 4

[0154] On the basis of Example 1, in step S3, the cerium fluoride in the additive C is replaced with magnesium oxide, and except for this, the preparation raw materials and the preparation method and the parameter conditions are basically the same as those of Example 1.

[0155] Example 5

[0156] On the basis of Example 1, in step S3, cerium fluoride in additive C is replaced by aluminum fluoride, and except for this, the raw materials and the preparation method and the parameter conditions, etc. are basically the same as Example 1.

[0157] Example 6

[0158] On the basis of Example 1, in step S1, calcium hydroxide Ca(OH)2 in additive B is replaced by calcium pyrophosphate Ca2O7P2, and except for this, the raw materials and the preparation method and the parameter conditions, etc. are basically the same as Example 1.

[0159] Example 7

[0160] On the basis of Example 1, after drying in step S2, directly crush and pass through a 325 mesh sieve to obtain the modified high-nickel positive electrode material of the application, that is, there is no mixing and secondary sintering of step S3, and except for this, the raw materials and the preparation method and the parameter conditions, etc. are basically the same as Example 1.

[0161] The partial parameters of Examples 1 to 7 are given in Table 1 as follows.

[0162] Table 1 Partial parameters of Examples 1 to 7

[0163] Comparative Example 1

[0164] In this example, a modified high-nickel positive electrode material is prepared, which is different from Example 1 in that:

[0165] In step S1, no additive B is added.

[0166] Comparative Example 2

[0167] In this example, a modified high-nickel positive electrode material is prepared, which is different from Example 1 in that:

[0168] In step S1, boron nitride is not contained in additive B.

[0169] Comparative Example 3

[0170] In this example, a modified high-nickel positive electrode material is prepared, which is different from Example 1 in that:

[0171] In step S1, calcium hydroxide is not contained in additive B.

[0172] Comparative Example 4

[0173] In this example, a modified high-nickel positive electrode material is prepared, which is different from Example 1 in that:

[0174] In step S1, no first holding platform is set, that is, directly heated from room temperature to the constant temperature of the second holding platform 780℃, and held for 12h.

[0175] Comparative Example 5

[0176] In this example, a modified high-nickel positive electrode material is prepared, which is different from Example 1 in that:

[0177] In step S1, the temperature of the first holding platform is set to 700°C.

[0178] Comparative Example 6

[0179] In this example, a modified high-nickel positive electrode material is prepared, which is different from Example 1 in that:

[0180] In step S1, the holding temperature of the first holding platform is 300°C.

[0181] Comparative Example 7

[0182] In this example, a modified high-nickel positive electrode material is prepared, which is different from Example 1 in that:

[0183] In step S1, no additive A is added.

[0184] Application Example

[0185] In this example, a lithium secondary battery is provided, which is as follows:

[0186] The positive electrode material prepared above, the conductive agent Super P, and the binder polyvinylidene fluoride (PVDF) are mixed and stirred uniformly at a mass ratio of 90:5:5, and N-methyl pyrrolidone (NMP) is added to prepare a positive electrode slurry (solid content about 40%) which is coated on a current collector aluminum foil, dried at 105°C, and then rolled at room temperature to a surface density of 2.8 g / cm 3 to 3.3 g / cm 3 , then punched and cut into round sheets to form a positive electrode sheet; wherein the positive electrode material is from the examples or comparative examples.

[0187] The assembly of the button cell is carried out in a glove box. The assembly is carried out in the order of "negative shell-foam nickel-lithium sheet -8 drops of electrolyte-separator 16 μm thick)-8 drops of electrolyte-positive electrode sheet-positive shell", wherein the electrolyte is composed of ethylene carbonate (EC), methyl ethyl carbonate (EMC), and dimethyl carbonate (DMC) (EC: EMC: DMC volume ratio = 1:1:1) containing 1.0 M LiPF6; the size of the battery shell (positive shell and negative shell) is 24 mm. The assembled button cell is placed in the mold groove of a hydraulic sealer (purchased from Shenzhen Keyi Zhida Technology Co., Ltd.), locked, and pressed >450 kg / cm 2Then unlock it and take out the sealed button cell battery, which is the lithium secondary battery obtained in this example.

[0188] Test case

[0189] This example tests the cross-sectional morphology of the modified high-nickel cathode materials obtained in the examples and comparative examples. The test method is to perform SEM testing after cross-section. The cross-sectional SEM images of Example 1 and Comparative Example 1 are shown in Figures 1 and 2. The test results show that the cross-sectional morphology of the modified high-nickel cathode materials obtained in the examples of this application is similar, both having radially arranged primary particles, which aggregate to form a secondary spherical structure; the gaps between the primary particles are filled with pore fillers derived from additive B. From the appearance, the cross-section of the modified high-nickel cathode material obtained in Example 1 is denser. In contrast, Comparative Example 1 lacks pore fillers, and the cross-section shows significantly more pores.

[0190] This example also tested the cross-sectional EDS spectra of the cathode materials obtained in Example 1 and Comparative Example 1. As shown in Figure 7, (a) is a cross-sectional SEM image of the cathode material obtained in Example 1, (b) is a mapping image of the B element distribution in the cross-section of the cathode material obtained in Example 1, where white dots represent B element, which is uniformly distributed in the internal and external layers. (c) is a cross-sectional SEM image of the cathode material obtained in Comparative Example 1, and (d) is a mapping image of the B element distribution in the cross-section of the cathode material obtained in Comparative Example 1, where white dots represent B element, which is faintly visible in the external layer. According to the cross-sectional EDS spectrum of Comparative Example 1, the boron element from additive C is mainly enriched on the surface of the material; according to the cross-sectional EDS spectrum of Example 1, the modified high-nickel cathode material of Example 1 also has relatively abundant boron element in its interior, including the core. Therefore, it can be concluded that the sintered material containing boron element from additive B does indeed have an interstitial filling effect.

[0191] This example also tested the withstand voltage performance of the modified high-nickel cathode materials obtained in the examples and comparative examples. The specific test method was as follows: gradually pressurize the cathode materials obtained in the examples and comparative examples to obtain the abrupt change point of dρ / dP. The pressure applied at the corresponding position is the collapse point; where ρ is the density and P is the pressure applied during the process; the test results are shown in Figure 3 and Table 2; the position indicated by the arrow in Figure 3 is the collapse point.

[0192] The cross-sectional SEM images and surface SEM images of Example 1 and Comparative Example 1 are shown in Figures 1-2 and Figures 8-9, respectively. They all show that the porosity of Example 1 is lower than that of Comparative Example 1. The porosity statistics are shown in Table 2.

[0193] Table 2. Performance of the high-nickel cathode materials obtained in the examples and comparative examples.

[0194] The results above show that, compared with Comparative Example 1, the Pτ of Example 1 is increased by more than 10%, and can reach about 60%, and in some cases even more than about 80%. This indicates that by allowing additive B to melt and infiltrate into the pores between primary particles, this application significantly improves the processing pressure resistance of the obtained modified high-nickel cathode material.

[0195] This example also tested the cycle performance of the lithium-ion secondary battery obtained from the application example. After cycling, the battery was disassembled, and the cross-sectional structure of the high-nickel cathode material after cycling was captured by SEM. The test method for cycle performance is as follows:

[0196] The charge-discharge cycle characteristics of coin cells were tested using a Blue Electric test cabinet at 25℃, with 1C = 200mAh / g set. Charge and discharge were performed at a rate of 1C within a voltage range of 2.8V to 4.25V. Specifically, the cells were charged at a constant current of 1C to 4.25V, then charged at a constant voltage of 4.25V to a cutoff current of 0.02C, rested for 5 minutes, and then discharged at 1C to 2.8V, rested for 5 minutes. The charge-discharge capacity after the first cycle was recorded. This cycle was repeated for 50 charge / discharge cycles, and the charge-discharge capacity after the 50th cycle was recorded.

[0197] Cycle capacity retention (%) = (50th cycle discharge capacity / 1st cycle discharge capacity) × 100%.

[0198] The test results of the cycle performance are shown in Table 3.

[0199] Table 3. Cyclic performance results of the high-nickel cathode materials obtained in the examples and comparative examples.

[0200] The cyclic process of Example 1 and Comparative Example 1 shows that, compared with Example 1, Comparative Example 1 decays faster in the first 50 weeks and has a faster overall decay rate, as shown in Figure 6.

[0201] Figures 4 and 5 show a comparison of the cross-sectional morphology of the high-nickel cathode materials after cycling in Example 1 and Comparative Example 1. Based on the cross-sectional test results of the cycled high-nickel cathode materials, the number and width of cracks in the modified high-nickel cathode materials obtained in the examples are significantly reduced. This demonstrates that the modified high-nickel cathode material provided in this application can significantly improve the stability of the cycling structure and ultimately significantly improve cycling performance.

[0202] In summary, this application, by leveraging the synergistic effects of additives A and B, and preferably by leveraging the synergistic effects of additives A, B, and C, and by precisely controlling the process parameters in each step of S1, such as the sintering regime and sintering temperature, unexpectedly obtained a modified high-nickel cathode material with excellent pressure resistance and cycle stability. When using the modified high-nickel cathode material of this application to prepare lithium secondary batteries, the cycle performance of the lithium secondary batteries can be significantly improved. Furthermore, lithium secondary batteries are expected to find wide application in the fields of power batteries, energy storage technology, and 3C small household appliance technology.

[0203] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the protection scope or spirit of this application. Furthermore, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

Claims

1. A modified high-nickel positive electrode material, characterized by, The modified high-nickel positive electrode material comprises: A base material having a chemical formula of LiNi x M y M’ z O2, wherein 0.80≤x≤0.98, 0 The base material has pores. a gap-filling substance, which is present inside the pores, the gap-filling substance comprising a sintered product derived from an additive B, the additive B comprising boron nitride and a calcium-containing compound. 2.The modified high-nickel positive electrode material of claim 1, characterized in that, The modified high-nickel positive electrode material further has a coating layer, the coating layer comprising a sintered product derived from an additive C, the additive C comprising at least one of boric acid, aluminum oxide, aluminum hydroxide, cerium oxide, aluminum fluoride, cerium fluoride, magnesium oxide, magnesium hydroxide; and / or, the additive C comprising boric acid, and at least one of aluminum oxide, aluminum hydroxide, cerium oxide, aluminum fluoride, cerium fluoride, magnesium oxide, magnesium hydroxide. 3.The modified high-nickel positive electrode material according to claim 1 or 2, characterized in that, The base material has a divergent structure; And / or, the collapse point P of the modified high-nickel positive electrode material is 4.0 V to 4.2 V. τ is 40 MPa to 65 MPa. 4.The modified high-nickel positive electrode material according to claim 1 or 2, characterized in that, The porosity inside the modified high-nickel positive electrode material is ≤3%. 5.The modified high-nickel positive electrode material according to claim 1 or 2, characterized in that, The concentration of B element derived from the additive B in the modified high-nickel positive electrode material is 200 ppm to 5000 ppm, and / or, the concentration of Ca element derived from the additive B in the modified high-nickel positive electrode material is 100 ppm to 2000 ppm.

6. A method for preparing a modified high-nickel positive electrode material, characterized by, The preparation method comprises the following steps: mixing a precursor Ni a M b (OH)2, a lithium source, an additive A and an additive B in an aerobic environment, and performing one-time sintering; The precursor Ni a M b (OH)2, 0.80≤a≤0.98, 0 The additive A is at least two of oxides, hydroxides or carbonates of Zr, Sr, Ca, Mg, Ba, Y, Nb, Ti, Mo, Sn, Ta, Sb, Bi and W; the additive B comprising boron nitride and a calcium-containing compound; The primary sintering comprises a first holding platform and a second holding platform; the temperature of the first holding platform is 350°C to 650°C; the temperature of the second holding platform is 680°C to 900°C.

7. The production method according to claim 6, characterized by, The holding time of the first holding platform is 2h to 6h; and / or, the holding time of the second holding platform is 6h to 16h.

8. The production method according to claim 6 or 7, characterized by, The preparation method further comprises: washing the product of the primary sintering with water, and mixing the water-washed product with an additive C before secondary sintering; the additive C comprising at least one of boric acid, aluminum oxide, aluminum hydroxide, cerium oxide, aluminum fluoride, cerium fluoride, magnesium oxide, magnesium hydroxide.

9. The production method according to claim 8, characterized by, The constant temperature of the secondary sintering is 200°C to 450°C; and / or, the constant temperature time of the secondary sintering is 5h to 10h.

10. A lithium secondary battery, characterized by comprising: The preparation raw material of the lithium secondary battery comprises the modified high-nickel positive electrode material according to any one of claims 1 to 5, or the modified high-nickel positive electrode material prepared by the preparation method according to any one of claims 6 to 9.

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