Lanthanum-titanium double-doped core-shell high-nickel precursor as well as preparation method and application thereof

Abstract

The invention provides a lanthanum-titanium double-doped core-shell high-nickel precursor as well as a preparation method and application thereof. The core-shell high-nickel precursor sequentially comprises an inner core and an outer shell coating the surface of the inner core from inside to outside, and the density of the inner core is greater than that of the outer shell; wherein the inner core comprises a lanthanum-doped high-nickel precursor material, and the shell comprises a titanium-doped high-nickel precursor material. According to the invention, through the synergistic cooperation of lanthanum doping in the inner core and titanium doping in the shell, the high-nickel precursor with the stable inner core and the loose outer layer is obtained, and the electrochemical performance of the positive electrode material is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical devices of lithium ion systems, and relates to a lanthanum-titanium dual-doped core-shell high-nickel precursor, a preparation method and uses thereof. Background Art

[0002] With the rapid development of electric vehicles and renewable energy storage systems, improving the energy density, cycle life, and safety of lithium-ion batteries has become a research focus. Since the increase in nickel content in high-nickel cathode materials can give the materials greater reversible capacity, the development of high-performance high-nickel cathode materials has become one of the main development directions for future power lithium battery materials.

[0003] The production of high nickel cathode materials generally adopts the complex coprecipitation method to prepare its polycrystalline spherical precursor (such as LiNi x Co y Mn z (OH)2, x≥0.6), and then the corresponding positive electrode material is prepared by mixed lithium sintering. High-nickel precursor materials have broad application prospects in lithium-ion batteries due to their high energy density and capacity performance. However, as the nickel content continues to increase and the Mn content decreases, the primary particles that make up the secondary spherical particles in the material become disordered in spatial orientation, resulting in anisotropic stress and strain at the grain boundaries within the secondary particles during the charge and discharge process, triggering microcracks within the secondary particles of the high-nickel precursor material, thereby significantly reducing the stability of the high-nickel positive electrode material and causing its cycle performance to decline.

[0004] Therefore, how to effectively avoid the generation of microcracks in high-nickel precursor materials and improve the structural stability, energy density and cycle performance of the resulting high-nickel positive electrode materials is a technical problem that needs to be solved urgently. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present invention aims to provide a lanthanum-titanium dual-doped core-shell high-nickel precursor, its preparation method, and its use. In the present invention, by synergistically combining lanthanum doping in the core and titanium doping in the shell, a high-nickel precursor with both a stable core and a loose outer layer is obtained, thereby improving the electrochemical performance of the positive electrode material.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a lanthanum-titanium dual-doped core-shell high-nickel precursor, wherein the core-shell high-nickel precursor comprises, from the inside to the outside, a core and a shell covering the surface of the core, wherein the density of the core is greater than the density of the shell;

[0008] The core comprises a lanthanum-doped high-nickel precursor material, and the shell comprises a titanium-doped high-nickel precursor material.

[0009] It should be noted that the definition of the high-nickel precursor in the present invention is that, based on the total molar amount of the main metal elements in the precursor excluding the doping elements being 100%, the molar ratio of nickel elements in the main metal elements is ≥80%, such as 80%, 83%, 85%, 88%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99%, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0010] In the high-nickel precursor material of the present invention, lanthanum ions are doped in the inner core. On the one hand, it can effectively induce the growth direction of the primary particles of the high-nickel precursor, increase the a / c axis ratio, make the precursor and the cathode material grow in a layered structure, and promote the inner part of the precursor to be in a layered structure and closely arranged. On the other hand, the lanthanum ion radius is relatively large, and after doping, it can effectively inhibit the volume change of the material during charge and discharge, reduce the structural stress, enhance the internal structural stability of the cathode material, and extend the service life of the battery; titanium ions are doped in the outer shell, which can more effectively disperse and transfer stress, reduce the problem of cracks appearing inside the sphere caused by stress concentration, promote the uniform distribution of each element and refine the morphology of the primary particles in the outer layer of the precursor, forming a porous and loose performance on the outside; the inner core and the outer shell cooperate synergistically. Different specific cations are doped in the inner core and the outer shell respectively, which changes the stacking morphology and internal structure of the primary particles in the inner and outer layers, forming a high-nickel precursor with a stable inner core and a loose outer layer, which is beneficial to lithium ion transmission and avoids the problems of surface rupture and crack appearance of the spherical precursor material; thereby improving the stability, cycle performance, specific capacity and energy density of the cathode material obtained from the precursor.

[0011] In the present invention, the doping elements in the inner core and the outer shell cannot be exchanged and are indispensable. Only by working together can a high-nickel precursor with a stable inner core and a loose outer layer be formed.

[0012] The following are the preferred technical solutions of the present invention, but do not limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0013] Preferably, the inner core is formed by arranging and assembling primary particles, and the morphology of the primary particles in the inner core is in the shape of thick strips or lamellar, and they are closely arranged.

[0014] At the same time, the outer shell is also formed by arranging and assembling primary particles, and the morphology of the primary particles in the outer shell is in the shape of thin strips or needles, and they are arranged in a loose and porous manner.

[0015] It is understandable that in the present invention, "thick" and "thin" in the primary particles are relative expressions, that is, in the strip structure, the relatively thinner structure is the thin strip, and the relatively thicker structure is the thick strip.

[0016] In the present invention, by doping lanthanum ions in the inner core and titanium ions in the outer shell, the morphology of the primary particles in the corresponding structure is regulated, thereby obtaining a high-nickel precursor with a stable inner core and a porous outer layer.

[0017] Preferably, the median particle size D50 of the inner core is 6 - 12 μm, such as 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm or 12 μm, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0018] Preferably, the median particle size D50 of the lanthanum-titanium double-doped core-shell high-nickel precursor is 13 - 15 μm, such as 13 μm, 13.5 μm, 14 μm, 14.5 μm or 15 μm, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0019] In the present invention, by regulating the median particle size D50 of the inner core to be 6 - 12 μm and / or the median particle size D50 of the lanthanum-titanium double-doped core-shell high-nickel precursor to be 13 - 15 μm, the relationship between the inner core and the outer shell thickness is coordinated, the stability of the internal crystal structure is better improved, and lithium ions are better transported, thereby improving the cycle stability and conductivity of the battery.

[0020] Preferably, in the high-nickel precursor material doped with lanthanum, the doping mass of lanthanum is 0.6% - 11.1%, such as 0.6%, 1%, 1.5%, 2%, 2.5%, 3%, 3.3%, 3.5%, 3.8%, 4%, 4.3%, 4.5%, 4.8%, 5%, 5.3%, 5.5%, 5.8%, 6%, 6.3%, 6.5%, 6.8%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11% or 11.1%, etc., preferably 3% - 7%, but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0021] Preferably, in the high-nickel precursor material doped with titanium, the doping mass of titanium is 0.08% - 4.8%, such as 0.08%, 0.1%, 0.5%, 1%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.8%, 3%, 3.5%, 4%, 4.5% or 4.8%, etc., preferably 1.5% - 3%, but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0022] In the present invention, appropriate amounts of lanthanum doping and titanium doping are beneficial to regulating the morphology and stacking mode of the primary particles of the core and the outer layer, thereby stabilizing the internal structure, dredging the lithium ion transmission channels, and optimizing the electrochemical performance. Preferably, the amount of lanthanum doping in the core is 3% - 7% and / or the amount of titanium doping in the shell is 1.5% - 3%, which further improves the cycle stability and conductivity of the battery.

[0023] Preferably, the specific surface area of the core-shell high-nickel precursor with dual lanthanum-titanium doping is 13 - 19 m 2 / g, such as 13 m 2 / g, 13.5 m 2 / g, 14 m 2 / g, 14.5 m 2 / g, 15 m 2 / g, 15.5 m 2 / g, 16 m 2 / g, 16.5 m 2 / g, 17 m 2 / g, 17.5 m 2 / g, 18 m 2 / g, 18.5 m 2 / g or 19 m 2 / g, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0024] Preferably, the tapped density of the core-shell high-nickel precursor with dual lanthanum-titanium doping is 1.8 - 2.1 g / cm 3 , such as 1.8 g / cm 3 , 1.85 g / cm 3 , 1.9 g / cm 3 , 1.95 g / cm 3 , 2 g / cm 3 , 2.05 g / cm 3 or 2.1 g / cm 3 etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0025] Preferably, the main metal elements in the high-nickel precursor materials in the core and the shell each independently include nickel, cobalt, and manganese.

[0026] In the present invention, it is preferred that the initial molar ratio of the main metal elements in the core and the shell is the same except for the doping elements.

[0027] In a second aspect, the present invention provides a method for preparing a core-shell high-nickel precursor with dual lanthanum-titanium doping as described in the first aspect, and the preparation method includes the following steps:

[0028] (1) The nickel-containing main metal salt solution, lanthanum salt solution, precipitant solution, and complexing agent solution are added in parallel to carry out the first coprecipitation reaction to obtain the core;

[0029] (2) After obtaining the core, the lanthanum salt solution is replaced with a titanium salt solution, and the second coprecipitation reaction is continued to obtain the core-shell high-nickel precursor doped with lanthanum and titanium.

[0030] The preparation method provided by the present invention, through the coprecipitation method, through the first precipitation reaction, the doping of lanthanum ions effectively induces the growth direction of primary particles in the core of the high-nickel precursor, increases the a / c axis ratio, makes the precursor and the cathode material grow towards the layered structure, promotes the layered structure inside the precursor, and arranges them closely. The titanium doping in the second coprecipitation reaction reduces stress concentration, makes each element evenly distributed, refines the morphology of primary particles in the shell of the high-nickel precursor, and forms a loose and porous morphology on the outside; it is more conducive to accurately controlling the doping amount and doping position of elements, and the preparation process has the advantages of low cost, simple operation, and easy control of doping, and is suitable for large-scale production.

[0031] Preferably, the concentration of the nickel-containing main metal salt solution in step (1) is 1 to 2.5 mol / L, such as 1 mol / L, 1.3 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.3 mol / L, or 2.5 mol / L, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0032] Preferably, the concentration of the lanthanum salt solution in step (1) is 0.5 to 1.5 mol / L, such as 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, or 1.5 mol / L, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0033] Preferably, the concentration of the titanium salt solution in step (2) is 0.01 to 0.5 mol / L, such as 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, or 0.5 mol / L, etc., but not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0034] Preferably, the feeding rates of the nickel-containing main metal salt solution in steps (1) and (2) are independently 5-80 L / h, such as 5 L / h, 10 L / h, 15 L / h, 20 L / h, 25 L / h, 30 L / h, 35 L / h, 40 L / h, 45 L / h, 50 L / h, 55 L / h, 60 L / h, 65 L / h, 70 L / h, 75 L / h or 80 L / h, etc., but are not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0035] Preferably, the feeding rate of the lanthanum salt solution in step (1) is 1.2-1.9 L / h, such as 1.2 L / h, 1.3 L / h, 1.4 L / h, 1.5 L / h, 1.6 L / h, 1.7 L / h, 1.8 L / h or 1.9 L / h, etc., but are not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0036] In the first co-precipitation reaction process of the present invention, the concentration of the nickel-containing main metal salt solution is adjusted to 1-2.5 mol / L and / or the concentration of the lanthanum salt solution is adjusted to 0.5-1.5 mol / L and / or the feeding rate of the nickel-containing main metal salt solution is 5-80 L / h and / or the feeding rate of the lanthanum salt solution is 1.2-1.9 L / h, thereby achieving precise control of the doping amount of lanthanum in the core, better regulating the morphology of the primary particles in the core, further adjusting the crystal structure and the morphology of the primary particles, enhancing the stability of the crystal structure, avoiding the collapse of the internal structure, suppressing the volume expansion during charge and discharge, prolonging the cycle life, reducing the decomposition of the electrolyte and side reactions, and significantly improving the thermal stability and the battery life of the battery.

[0037] Preferably, the feeding rate of the titanium salt solution in step (2) is 0.8-1 L / h, such as 0.8 L / h, 0.9 L / h or 1 L / h, etc., but are not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0038] In the second co-precipitation reaction process of the present invention, the concentration of the nickel-containing main metal salt solution is adjusted to 1-2.5 mol / L and / or the concentration of the titanium salt solution is adjusted to 0.01-0.5 mol / L and / or the feeding rate of the nickel-containing main metal salt solution is 5-80 L / h and / or the feeding rate of the titanium salt solution is 0.8-1 L / h, thereby achieving precise control of the doping amount of titanium in the shell, effectively regulating the morphology of the primary particles in the shell on the basis of the morphology of the primary particles in the core, better playing the role of refining the crystal grains, improving the lithium-ion diffusion efficiency, thereby enhancing the rate performance, and using the "zero strain" characteristic to suppress the volume expansion during charge and discharge and improve the cycle life.

[0039] Preferably, the pH value of the first coprecipitation reaction in step (1) is 11 to 11.5, such as 11, 11.1, 11.2, 11.3, 11.4, or 11.5, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0040] Preferably, the reaction temperature of the first coprecipitation reaction in step (1) is 50 to 75 °C, such as 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, or 75 °C, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0041] Preferably, the reaction time of the first coprecipitation reaction in step (1) is 20 to 50 h, such as 20 h, 25 h, 30 h, 35 h, 40 h, 45 h, or 50 h, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0042] Preferably, the pH value of the second coprecipitation reaction in step (2) is 10.5 to 11, such as 10.5, 10.6, 10.7, 10.8, 10.9, or 11, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0043] Preferably, the reaction temperature of the second coprecipitation reaction in step (2) is 50 to 75 °C, such as 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, or 75 °C, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0044] Preferably, the rotation speeds of the first coprecipitation reaction in step (1) and the second coprecipitation reaction in step (2) are each independently 80 to 260 rpm, such as 80 rpm, 90 rpm, 100 rpm, 130 rpm, 150 rpm, 180 rpm, 200 rpm, 230 rpm, 250 rpm, or 260 rpm, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0045] It should also be noted that the anions in the high-nickel precursor material in the present invention can be adaptively adjusted according to the specific types of precipitants. For example, it can be a high-nickel precursor material in a hydroxide system or a high-nickel precursor material in a carbonate system.

[0046] Optionally, the precipitant includes but is not limited to at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, or potassium hydroxide, etc.; the complexing agent includes but is not limited to at least one of ammonia water, ammonium carbonate, ammonium bicarbonate, oxalic acid, glycine, citric acid, salicylic acid, ammonium nitrate, or EDTA (ethylenediaminetetraacetic acid), etc.

[0047] Optionally, the concentration of the precipitant solution is 1 to 10 mol / L, such as 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L or 10 mol / L, etc., and the concentration of the complexing agent solution is 1 to 10 mol / L, such as 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L or 10 mol / L, etc. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0048] In addition, during the preparation process of the present invention, a bottom liquid can be added in advance to the reaction vessel (such as a reaction kettle) before the raw materials are added in parallel.

[0049] Optionally, the bottom liquid includes water, a precipitant and a complexing agent.

[0050] Optionally, the pH value of the bottom liquid is 11.5 to 12, such as 11.5, 11.6, 11.7, 11.8, 11.9 or 12, etc., and the concentration of the complexing agent in the bottom liquid is 7 to 10 g / L, such as 7 g / L, 8 g / L, 9 g / L or 10 g / L, etc. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0051] Furthermore, the preparation method in the present invention is carried out under a nitrogen atmosphere.

[0052] In a third aspect, the present invention provides a cathode material, which is obtained by mixing and sintering a core-shell high-nickel precursor with double doping of lanthanum and titanium as described in the first aspect or a core-shell high-nickel precursor prepared by the preparation method as described in the second aspect with a lithium source.

[0053] It should be noted that the specific preparation processes for obtaining the cathode material from the high-nickel precursor material in the present invention are all conventional technical solutions, and the present invention is applicable to any conventional technical solutions that can be obtained within a reasonable range by those skilled in the art.

[0054] Exemplarily, the present invention provides a preparation method for a cathode material, and the preparation method includes:

[0055] Mixing a core-shell high-nickel precursor with double doping of lanthanum and titanium provided in the first aspect or a core-shell high-nickel precursor prepared by the preparation method as described in the second aspect with a lithium source in a molar ratio of Me:Li of 1:(1 to 1.5) uniformly, and then performing high-temperature sintering at a sintering temperature of 500 to 1000 for 6 to 20 h under an oxygen-containing atmosphere, and naturally cooling to room temperature to obtain the cathode material;

[0056] Optionally, the lithium source includes but is not limited to at least one of lithium hydroxide, lithium carbonate, or lithium acetate; the oxygen-containing atmosphere includes an air atmosphere or an oxygen atmosphere, etc.

[0057] Those skilled in the art can make adaptive selection and adjustment of the above preparation processes and parameters according to actual needs.

[0058] The positive electrode material provided by the present invention has a stable precursor raw material structure without microcracks. The high-nickel ternary precursor is doped and modified with titanium and lanthanum elements, significantly improving the cycle stability, enhancing the electronic conductivity of the battery material, and extending the service life of the battery; among them, the lanthanum ion radius is relatively large, and after doping, the lattice spacing is enlarged through the "strut effect" to inhibit the irreversible phase change of the high-nickel positive electrode material during cycling. During the cycling process, lanthanum combines with oxygen to reduce oxygen vacancies and avoid the collapse of the material structure; reduce interfacial side reactions; the titanium ion radius is relatively small, and after doping, it occupies the stable sites of nickel and cobalt, reducing the volume change and lattice stress during charge and discharge, and inhibiting the cracking phenomenon of secondary particles during stirring and sintering, thereby reducing the risk of electrolyte penetration and side reactions. In addition, titanium doping can reduce the mixing of Li+ and Ni2+ in the layered structure, refine the grains, and improve the lithium ion diffusion efficiency, thereby enhancing the rate performance and cycle life.

[0059] In a fourth aspect, the present invention also provides an electrochemical device, and the electrochemical device includes the positive electrode material as described in the third aspect.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] (1) For the high-nickel precursor material in the present invention, lanthanum ion doping is carried out in the inner core. On the one hand, it can effectively induce the growth direction of the primary particles of the high-nickel precursor, increase the a / c axis ratio, make the precursor and the positive electrode material grow in a layered structure, and promote the layered structure inside the precursor, closely arranged. On the other hand, the lanthanum ion radius is relatively large, and after doping, it can effectively inhibit the volume change of the material during charge and discharge, reduce the structural stress, enhance the internal structural stability of the positive electrode material, and extend the service life of the battery; titanium ion doping is used in the outer shell, which can more effectively disperse and transfer stress, reduce the problem of cracks appearing inside the sphere caused by stress concentration, promote the uniform distribution of each element and refine the morphology of the primary particles in the outer layer of the precursor, forming a porous performance on the outside; the inner core and the outer shell cooperate synergistically. The inner core and the outer shell are doped with different specific cations respectively, changing the stacking morphology and internal structure of the primary particles in the inner and outer layers, forming a high-nickel precursor with a stable inner core and a porous outer layer, which is beneficial to lithium ion transmission and avoids the problems of surface rupture and crack appearance of the spherical precursor material; thereby improving the stability, cycle performance, specific capacity and energy density of the positive electrode material obtained from the precursor.

[0062] (2) The preparation method provided by the present invention, through the co-precipitation method, in the first precipitation reaction, the doping of lanthanum ions effectively induces the growth direction of primary particles in the inner core of the high-nickel precursor, increases the a / c axis ratio, enables the precursor and the cathode material to grow towards a layered structure, promotes the formation of a layered structure inside the precursor, with close arrangement. And the titanium doping in the second co-precipitation reaction reduces stress concentration, makes each element evenly distributed, refines the morphology of primary particles in the outer shell of the high-nickel precursor, and forms a loose and porous morphology on the outside; it is more conducive to accurately controlling the doping amount and doping position of elements, and the preparation process has the advantages of low cost, simple operation, easy doping control, etc., and is suitable for large-scale production.

[0063] (3) The cathode material provided by the present invention has a stable precursor raw material structure without microcracks. The high-nickel ternary precursor is doped and modified with two elements, titanium and lanthanum, which significantly improves the cycle stability, improves the electronic conductivity of the battery material, and extends the service life of the battery; among them, the lanthanum ion has a relatively large radius. After doping, the lattice spacing is enlarged through the "pillar effect", which inhibits the irreversible phase change of the high-nickel cathode material during cycling. During the cycling process, lanthanum combines with oxygen to reduce oxygen vacancies and avoid the collapse of the material structure; it reduces interfacial side reactions; the titanium ion has a relatively small radius. After doping, it occupies the stable points of nickel and cobalt, reduces the volume change and lattice stress during charge and discharge, inhibits the cracking phenomenon of secondary particles during stirring and sintering, thereby reducing the risk of electrolyte penetration and side reactions. In addition, titanium doping can reduce the mixing of Li+ and Ni2+ in the layered structure, refine the grains, and improve the lithium ion diffusion efficiency, thereby enhancing the rate performance and cycle life. Detailed implementation manners

[0064] The technical solutions of the present invention will be further described below through specific implementation manners. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0065] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusion.

[0066] In the description of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, "a plurality of" means more than two unless otherwise specifically defined.

[0067] Example 1

[0068] This embodiment provides a core-shell high-nickel precursor doped with lanthanum and titanium (D50 is 13 μm). The core-shell high-nickel precursor sequentially includes an inner core (D50 is 10 μm) and a shell coated on the surface of the inner core from inside to outside. The density of the inner core is greater than that of the shell;

[0069] The inner core includes a nickel-cobalt-manganese hydroxide precursor material doped with lanthanum, and the shell includes a nickel-cobalt-manganese hydroxide precursor material doped with titanium;

[0070] In the inner core, the doping mass of lanthanum is 5%; in the shell, the doping mass of titanium is 2.5%.

[0071] The preparation method of the lanthanum-titanium double-doped core-shell high-nickel precursor is as follows:

[0072] (1) Prepare a mixed sulfate solution with a molar ratio of nickel, cobalt, and manganese of 8:1:1 and a concentration of 2 mol / L, a lanthanum sulfate solution with a concentration of 1.0 mol / L, a titanium sulfate solution with a concentration of 0.4 mol / L, a sodium hydroxide precipitant solution with a concentration of 2 mol / L, and an ammonia water solution with a concentration of 1.5 mol / L respectively;

[0073] At the same time, prepare a bottom liquid in the reaction kettle. The bottom liquid includes sodium hydroxide, ammonia water, and water. The pH value of the bottom liquid is 11.8, and the ammonia concentration is 8 g / L;

[0074] (2) Add the nickel-cobalt-manganese mixed salt solution, lanthanum sulfate solution, precipitant solution, and complexing agent solution into the bottom liquid in parallel. Among them, the feeding rate of the nickel-cobalt-manganese mixed salt solution is 30 L / h, and the feeding rate of the lanthanum sulfate solution is 1.4 L / h. Adjust the pH value during the reaction process to 11.5, and carry out the first co-precipitation reaction at 60 °C with a rotation speed of 200 rpm. When the D50 of the particle size reaches 10 μm, the inner core is formed;

[0075] After the inner core is formed, suspend the addition of the lanthanum sulfate solution, adjust to add a titanium sulfate solution with a feeding rate of 0.9 L / h, and reduce the reaction pH to 10.8, and continue to carry out the second co-precipitation reaction to obtain a precursor slurry with a D50 of 13 μm for the final product;

[0076] (3) Age, wash, and dry the precursor slurry in sequence to obtain the lanthanum-titanium double-doped core-shell high-nickel precursor.

[0077] Example 2

[0078] This embodiment provides a core-shell high-nickel precursor doped with lanthanum and titanium (D50 is 13 μm). The core-shell high-nickel precursor sequentially includes an inner core (D50 is 6 μm) and a shell coated on the surface of the inner core from inside to outside. The density of the inner core is greater than that of the shell;

[0079] The core includes a nickel cobalt manganese hydroxide precursor material doped with lanthanum, and the shell includes a nickel cobalt manganese hydroxide precursor material doped with titanium;

[0080] In the core, the doping mass of lanthanum is 3%; in the shell, the doping mass of titanium is 1.5%.

[0081] The preparation method of the core-shell high-nickel precursor with dual lanthanum and titanium doping is as follows:

[0082] (1) Prepare a mixed sulfate solution of nickel, cobalt and manganese with a molar ratio of 8:1:1 and a concentration of 2.5 mol / L, a lanthanum sulfate solution with a concentration of 0.5 mol / L, a titanium sulfate solution with a concentration of 0.1 mol / L, a sodium hydroxide precipitant solution with a concentration of 1.5 mol / L and an ammonia water solution with a concentration of 1 mol / L respectively;

[0083] At the same time, prepare a bottom liquid in the reaction kettle. The bottom liquid includes sodium hydroxide, ammonia water and water. The pH value of the bottom liquid is 11.8 and the ammonia concentration is 8 g / L;

[0084] (2) Add the nickel cobalt manganese mixed salt solution, lanthanum sulfate solution, precipitant solution and complexing agent solution into the bottom liquid in parallel. Among them, the feeding rate of the nickel cobalt manganese mixed salt solution is 50 L / h, the feeding rate of the lanthanum sulfate solution is 1.2 L / h, adjust the pH value during the reaction process to 11.0, and carry out the first co-precipitation reaction at 50 °C with a rotation speed of 200 rpm. When D50 reaches 6 μm, the core is formed;

[0085] After the core is formed, suspend the addition of the lanthanum sulfate solution, adjust to add a titanium sulfate solution with a feeding rate of 0.8 L / h, and reduce the reaction pH to 10.5, and continue to carry out the second co-precipitation reaction to obtain a precursor slurry with a D50 of 13 μm for the final product;

[0086] (3) Age, wash and dry the precursor slurry in sequence to obtain the core-shell high-nickel precursor with dual lanthanum and titanium doping.

[0087] Example 3

[0088] This example provides a core-shell high-nickel precursor with dual lanthanum and titanium doping (D50 is 15 μm). The core-shell high-nickel precursor includes a core (D50 is 12 μm) and a shell coated on the surface of the core from the inside to the outside. The density of the core is greater than the density of the shell;

[0089] The core includes a nickel cobalt manganese hydroxide precursor material doped with lanthanum, and the shell includes a nickel cobalt manganese hydroxide precursor material doped with titanium;

[0090] In the core, the doping mass of lanthanum is 7%; in the shell, the doping mass of titanium is 3%.

[0091] The preparation method of the core-shell high-nickel precursor with lanthanum and titanium co-doping is as follows:

[0092] (1) Prepare a mixed sulfate solution with a molar ratio of nickel, cobalt, and manganese of 8:1:1 at 1.5 mol / L respectively, a lanthanum sulfate solution with a concentration of 1.5 mol / L, a titanium sulfate solution with a concentration of 0.5 mol / L, a sodium hydroxide precipitant solution with a concentration of 2 mol / L, and an ammonia water solution with a concentration of 1.5 mol / L.

[0093] At the same time, prepare a bottom liquid in the reaction kettle. The bottom liquid includes sodium hydroxide, ammonia water, and water. The pH value of the bottom liquid is 11.8, and the ammonia concentration is 8 g / L.

[0094] (2) Add the nickel-cobalt-manganese mixed salt solution, lanthanum sulfate solution, precipitant solution, and complexing agent solution into the bottom liquid in a co-current manner. Among them, the feeding rate of the nickel-cobalt-manganese mixed salt solution is 10 L / h, and the feeding rate of the lanthanum sulfate solution is 1.9 L / h. Adjust the pH value during the reaction process to 11.3, and carry out the first co-precipitation reaction at 60 °C with a rotation speed of 200 rpm. When D50 reaches 12 μm, the core is formed.

[0095] After the core is formed, suspend the addition of the lanthanum sulfate solution, adjust to add the titanium sulfate solution with a feeding rate of 1 L / h, and reduce the reaction pH to 10.8. Continue to carry out the second co-precipitation reaction to obtain a precursor slurry with a D50 of 15 μm for the final product.

[0096] (3) Age, wash, and dry the precursor slurry in sequence to obtain the core-shell high-nickel precursor with lanthanum and titanium co-doping.

[0097] Example 4

[0098] The difference between this example and Example 1 is that in step (1) of this example, a mixed sulfate solution with a molar ratio of nickel, cobalt, and manganese of 9:0.5:0.5 at 2 mol / L is prepared.

[0099] All other conditions are the same as those in Example 1.

[0100] Example 5

[0101] The difference between this example and Example 1 is that the D50 of the core in this example is 5 μm.

[0102] In step (2) of the preparation method, when the D50 of the particle size reaches 5 μm, the core is formed.

[0103] All other conditions are the same as those in Example 1.

[0104] Example 6

[0105] The difference between this example and Example 1 is that the D50 of the core in this example is 12.5 μm.

[0106] In step (2) of the preparation method, when the D50 of the particle size reaches 12.5 μm, the core is formed.

[0107] All other conditions are the same as those in Example 1.

[0108] Example 7

[0109] The difference between this example and Example 1 is that in the core of this example, the doping mass of lanthanum is 11%.

[0110] In step (1) of the preparation method, the concentration of lanthanum sulfate is 2 mol / L.

[0111] All other conditions are the same as those in Example 1.

[0112] Example 8

[0113] The difference between this example and Example 1 is that in the core of this example, the doping mass of lanthanum is 0.5%.

[0114] In step (1) of the preparation method, the concentration of lanthanum sulfate is 0.4 mol / L.

[0115] All other conditions are the same as those in Example 1.

[0116] Example 9

[0117] The difference between this example and Example 1 is that in the shell of this example, the doping mass of titanium is 5%.

[0118] In step (1) of the preparation method, the concentration of titanium sulfate is 1 mol / L.

[0119] All other conditions are the same as those in Example 1.

[0120] Comparative Example 1

[0121] The difference between this comparative example and Example 1 is that neither lanthanum doping nor titanium doping is carried out in the high-nickel precursor of this comparative example, that is, it is a spherical nickel-cobalt-manganese hydroxide precursor with a D50 of 13 μm.

[0122] In the preparation method, the preparation of lanthanum sulfate solution and titanium sulfate solution in step (1) is not carried out, and in step (2), the first co-precipitation reaction is directly carried out until the particle size D50 reaches 13 μm, and then the reaction is stopped.

[0123] All other conditions are the same as those in Example 1.

[0124] Comparative Example 2

[0125] The difference between this comparative example and Example 1 is that lanthanum doping in the core is not carried out in this comparative example.

[0126] In the preparation method, the preparation of lanthanum sulfate solution in step (1) is not carried out, and lanthanum sulfate solution is not added in step (2).

[0127] All other conditions are the same as those in Example 1.

[0128] Comparative Example 3

[0129] The difference between this comparative example and Example 1 is that lanthanum doping in the core is not carried out in this comparative example.

[0130] In the preparation method, the preparation of lanthanum titanium sulfate solution in step (1) is not carried out. After stopping adding lanthanum sulfate solution in step (2), the second co-precipitation reaction can be continued.

[0131] All other conditions are the same as those in Example 1.

[0132] The specific surface area and tap density of the high-nickel precursors provided in Examples 1-9 and Comparative Examples 1-3 were tested:

[0133] Specific surface area: Tested using a fully automatic specific surface area and pore size analyzer (V-Sorb X800(DM)).

[0134] Tap density: Tested using a single-station tap density tester, and the general method for testing the tap density of powder products in GB / T 21354—2008 was used.

[0135] The test results of the above tests are shown in Table 1.

[0136] Table 1

[0137] <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Tap density (g / cm 3 )]]> Example 1 14.7 2.0 Example 2 16.0 1.93 Example 3 15.1 1.92 Example 4 14.8 1.91 Example 5 17.9 1.90 Example 6 11.3 1.96 Example 7 25.1 1.69 Example 8 13.5 1.91 Example 9 24.7 1.80 Comparative Example 1 12.5 1.91 Comparative Example 2 13.6 1.93 Comparative Example 3 12.8 1.89

[0138] [Preparation of Cathode Material]

[0139] The high-nickel precursors provided in Examples 1-9 and Comparative Examples 1-3 were respectively calcined with lithium hydroxide. The ratio of the precursor to the lithium source was 1:1.5. They were mixed evenly by a high-speed mixer and sintered in a box furnace under an air atmosphere. The sintering temperature was 800 °C, and the high-temperature sintering duration was 12 h. After cooling to room temperature, they were pulverized and sieved to obtain the cathode material.

[0140] [Preparation and Performance Test of Lithium-Ion Battery]

[0141] Preparation of lithium-ion battery:

[0142] The cathode materials, conductive carbon black SP (TIMCAL), and polyvinylidene fluoride PVDF (HSV900) provided in Examples 1-9 and Comparative Examples 1-3 were mixed at a mass ratio of 90:5:5, respectively. N-methylpyrrolidone was used as the solvent and mixed and stirred into a slurry. The obtained slurry was evenly coated on the aluminum foil with a doctor blade having a coating gap of 100 μm. After coating, it was first dried by blowing air at 120 °C, then roll-pressed. Finally, the dried electrode sheet was cut into a Φ12 circular electrode sheet, and the weight of the electrode sheet was measured after vacuum drying at 120 °C to obtain the cathode electrode sheet of the button half-cell; the negative electrode was a Φ14 metallic lithium sheet, the separator was a Φ19 PP microporous membrane (Celgard 2400), and the electrolyte was a lithium battery basic electrolyte, that is, EC and DEC were used as a mixed solvent at a volume ratio of 1:1, and 1.1 mol / L of LiPF6 was added. The cathode electrode sheet, metallic lithium sheet, separator, and electrolyte were assembled to obtain a button cell.

[0143] Performance test:

[0144] At room temperature of 25 °C, within a voltage range of 2.0 to 4.8 V, the charge-discharge test capacity was performed at 0.1C to obtain the first discharge capacity and the first Coulomb efficiency; the charge-discharge cycle test was performed at 1C to obtain the capacity retention rate after 50 cycles. The test results are shown in Table 2.

[0145] Table 2

[0146]

[0147]

[0148] The applicant declares that the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A lanthanum-titanium double-doped core-shell high-nickel precursor, characterized in that, The core-shell high-nickel precursor includes a core and a shell coated on the surface of the core in sequence from inside to outside, and the density of the core is greater than that of the shell; Among them, the core includes a high-nickel precursor material doped with lanthanum, and the shell includes a high-nickel precursor material doped with titanium.

2. The core-shell high-nickel precursor doped with lanthanum and titanium according to claim 1, characterized in that The median particle size D50 of the core is 6-12 μm; Preferably, the median particle size D50 of the core-shell high-nickel precursor doped with lanthanum and titanium is 13-15 μm.

3. The lanthanum-titanium double-doped core-shell high-nickel precursor according to claim 1 or 2, characterized in that, In the high-nickel precursor material doped with lanthanum, the doping mass of lanthanum is 0.6%-11.1%, preferably 3%-7%; Preferably, in the high-nickel precursor material doped with titanium, the doping mass of titanium is 0.08%-4.8%, preferably 1.5%-3%.

4. The core-shell high-nickel precursor doped with lanthanum and titanium according to claim 1, wherein The specific surface area of the lanthanum-titanium double-doped core-shell high-nickel precursor is 13 to 19 m 2 / g; Preferably, the tap density of the lanthanum-titanium double-doped core-shell high-nickel precursor is 1.8 to 2.1 g / cm 3 ; Preferably, the main metal elements in the high-nickel precursor materials in the core and the shell each independently include nickel, cobalt, and manganese.

5. A method for preparing a lanthanum-titanium double-doped core-shell high-nickel precursor as described in any one of claims 1-4, characterized in that, The preparation method includes the following steps: (1) A nickel-containing main metal salt solution, a lanthanum salt solution, a precipitant solution, and a complexing agent solution are added in parallel to carry out a first co-precipitation reaction to obtain a core; (2) After obtaining the core, the lanthanum salt solution is replaced with a titanium salt solution, and the second co-precipitation reaction is continued to obtain the core-shell high-nickel precursor doped with lanthanum and titanium.

6. The preparation method according to claim 5, characterized in that, The concentration of the nickel-containing main metal salt solution in step (1) is 1-2.5 mol / L; Preferably, the concentration of the lanthanum salt solution in step (1) is 0.5-1.5 mol / L; Preferably, the concentration of the titanium salt solution in step (2) is 0.01-0.5 mol / L.

7. The preparation method according to claim 5, characterized in that, The feeding rates of the nickel-containing main metal salt solutions in step (1) and step (2) are each independently 5-80 L / h; Preferably, the feeding rate of the lanthanum salt solution in step (1) is 1.2-1.9 L / h; Preferably, the feeding rate of the titanium salt solution in step (2) is 0.8-1 L / h.

8. The preparation method according to claim 5, characterized in that, The pH value of the first co-precipitation reaction in step (1) is 11-11.5, the reaction temperature of the first co-precipitation reaction is 50-75 °C, and the reaction time of the first co-precipitation reaction is 20-50 h; Preferably, the pH value of the second co-precipitation reaction in step (2) is 10.5-11, and the reaction temperature of the second co-precipitation reaction is 50-75 °C.

9. A cathode material, characterized in that, The positive electrode material is obtained by mixing and sintering the core-shell high-nickel precursor doped with lanthanum and titanium according to any one of claims 1-4 or the core-shell high-nickel precursor prepared by the preparation method according to any one of claims 5-8 with a lithium source.

10. An electrochemical device, characterized in that, The electrochemical device includes the positive electrode material according to claim 9.

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