Ternary positive electrode material as well as preparation method and application thereof
Through the methods of multi-element doping and surface coating, the problem of structural instability of ternary positive electrode materials at high energy density was solved, the thermal stability and electrochemical performance of the materials were improved, and the risks of cation mixing and side reactions were reduced.
Patent Information
- Application Number
- CN202510810752.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-17
- Publication Date
- 2025-09-16
AI Technical Summary
Existing ternary positive electrode materials have structural instability and safety issues at high energy density, especially under abuse conditions, they are prone to phase change, volume expansion and electrochemical performance degradation, leading to the risk of thermal runaway.
By adopting the method of multi-element bulk doping and surface coating, elements such as Na+, Mg2+, Zr4+ are introduced into the ternary positive electrode material to form a fast ion conductor lithium silicate component, expand the lithium ion layer spacing, and form a uniform and dense coating layer on the material surface, thereby enhancing structural stability and suppressing electrolyte side reactions.
The thermal stability and electrochemical performance of the ternary positive electrode material were significantly improved, the degree of cation mixing was reduced, and the structural stability and cycle stability of the material under deep delithiation conditions were improved.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of lithium-ion batteries, and in particular relates to a ternary positive electrode material, a preparation method thereof, and applications thereof. Background Art
[0002] Lithium-ion batteries, with their high energy / power density, long cycle life, and environmental friendliness, have become the most important energy storage device on the market, finding widespread application in energy systems such as portable electronic devices, electric vehicles, and large-scale energy storage systems. With the transformation of energy structures and the upgrade of large electrical equipment, lithium-ion batteries have undoubtedly brought significant changes and convenience to our lives. However, safety issues cannot be ignored, especially with the advent of high-energy-density power lithium-ion batteries, which have made safety issues even more prominent. Therefore, to achieve longer lifespans and wider applications, there is an urgent need for safe lithium-ion batteries.
[0003] Ternary cathode materials are one of the most widely used cathode materials for power batteries due to their high energy density, low cost, and market-leading performance. However, as nickel content increases, capacity retention and peak exothermic reaction temperature decrease, significantly deteriorating battery life and safety. Therefore, research on the electrochemical performance and thermal stability of ternary cathode materials is becoming increasingly important.
[0004] Studies have shown that under conditions of abuse, ultra-high nickel cathode materials gradually undergo phase transitions at the surface, and during charge and discharge, they experience volume expansion and increased cation mixing due to repeated lithium insertion and extraction. These phenomena have a significant impact on the overall performance of the battery: crack formation and surface reconstruction lead to increased electrochemical impedance, causing a decrease in reversible capacity, and the resulting electrochemical polarization or concentration polarization leads to increased heat generation from the electrochemical reaction. Structural damage to the material and oxygen release also reduce the thermal stability of the material, triggering side reactions with the electrolyte, resulting in intense heat release and ultimately thermal runaway. Therefore, it can be concluded that the safety performance of the battery is closely linked to changes in the material structure.
[0005] In the past few decades, extensive research has been conducted to improve the safety of cathode materials. Based on this, many strategies have been adopted to optimize the materials to achieve the coexistence of high capacity and high thermal stability. As one of the most common modification methods, atomic doping enhances the structural integrity of the cathode by substituting atoms in the lattice with stable dopants. For example, by introducing a small amount of magnesium, aluminum, titanium, molybdenum, tungsten, and sodium to replace Ni, Co, and Mn sites, the volume change during phase transformation can be effectively reduced, thus maintaining the crystal structure under deep de-lithiation conditions. Surface coating is another widely used modification method, aiming to form a thermodynamically more stable coating on the material surface to reduce side reactions between the electrode material and the electrolyte. However, the insulation of many coatings hinders the performance of the battery at high charge-discharge rates. To ensure the smooth transmission of Li + , lithium compounds and ion-conductive polymers are also used as surface coating materials. At the same time, the method of simultaneous doping and coating, as a dual modification strategy, can simultaneously combat microcracks and surface side reactions, but there is still much room for improvement in its safety performance and electrochemical stability performance. Summary of the Invention
[0006] In view of this, the technical problem to be solved by the present invention is to provide a ternary cathode material with good thermal stability and excellent electrochemical performance, its preparation method and application.
[0007] The present invention provides a ternary cathode material, and the chemical formula of the ternary cathode material is Li a Ni x Co y Mn z Si b Al c Na d M e A f O2; wherein, 0.10 ≤ x ≤ 0.99, 0.01 ≤ y ≤ 0.40, z = 1 - x - y, 0.95 ≤ a ≤ 1.05, 0 < b ≤ 0.05, 0 < c ≤ 0.05, 0 < d ≤ 0.05, 0 ≤ e ≤ 0.05, 0 < f ≤ 0.05; M is selected from one or more of magnesium, potassium, zinc, zirconium, titanium, strontium, cesium, and calcium; A is selected from one or more of strontium, potassium, and cesium. <00
[0009] Preferably, 0.90≤x≤0.99, 0.01≤y≤0.10.
[0010] Preferably, the DSC decomposition temperature of the ternary cathode material is ≥245°C;
[0011] And / or, the lithium-nickel mixing value of the ternary positive electrode material is ≤3.0%;
[0012] And / or, the unit cell parameter c value of the ternary cathode material is ≥14.19;
[0013] And / or, the D50 of the ternary positive electrode material is 8.5 to 15 μm.
[0014] The present invention also provides a method for preparing the above-mentioned ternary cathode material, comprising the following steps:
[0015] S1) mixing a ternary precursor, a lithium source, and a primary additive to obtain a mixture A; wherein the primary additive comprises a silicate group; and the primary additive comprises at least two of the metal elements sodium, aluminum, magnesium, potassium, zinc, zirconium, titanium, strontium, cesium, and calcium, and includes the metal elements sodium and aluminum;
[0016] S2) sintering the mixture A at a high temperature in an oxidizing atmosphere and crushing the mixture to obtain a positive electrode material B;
[0017] S3) mixing the positive electrode material B with a secondary additive to obtain a mixture C; the secondary additive comprises one or more of the metal elements strontium, potassium and cesium;
[0018] S4) sintering the mixture C at a low temperature in an oxidizing atmosphere and sieving to obtain a ternary positive electrode material.
[0019] Preferably, the general formula of the ternary precursor is Ni x Co y Mn z (OH)2; wherein, 0.10≤x≤0.99, 0.01≤y≤0.40, z=1-xy;
[0020] And / or, the lithium source is selected from one or more of LiOH, LiOH·H2O and Li2CO3.
[0021] Preferably, the primary additive is selected from one or more of sodium silicate, potassium silicate, zinc silicate, zirconium silicate, calcium silicate, titanium silicate, magnesium silicate, strontium silicate, cesium silicate, calcium magnesium silicate, magnesium aluminum silicate, sodium aluminum silicate, sodium zirconium silicate, sodium titanate silicate, lithium sodium magnesium silicate, lithium aluminum silicate, lithium magnesium silicate, sodium magnesium aluminum silicate and potassium sodium aluminum silicate;
[0022] And / or, the secondary additive is selected from one or more of strontium hydroxide, potassium nitrate and cesium phosphate.
[0023] Preferably, the total molar number of elements nickel, cobalt and manganese in the ternary precursor and the molar ratio of the lithium source is 1:(1.00 - 1.10);
[0024] And / or, the addition amount of the primary additive is 100 - 5000 ppm of the mass of the ternary precursor;
[0025] And / or, the addition amount of the secondary additive is 100 - 5000 ppm of the mass of the cathode material B.
[0026] Preferably, in the step S2), the temperature of the high-temperature sintering is 700°C - 900°C; the time of the high-temperature sintering is 10 - 20 h; the heating rate of the high-temperature sintering is 1 - 5°C / min;
[0027] In the step S4), the temperature of the low-temperature sintering is 200°C - 650°C; the time of the low-temperature sintering is 4 - 10 h; the heating rate of the low-temperature sintering is 0.5 - 5°C / min.
[0028] The present invention also provides a lithium-ion battery, including the above ternary cathode material.
[0029] The present invention provides a ternary cathode material, and the chemical formula of the ternary cathode material is Li a Ni x Co y Mn z Si b Al c Na d M e A f O2; wherein, 0.10 ≤ x ≤ 0.99, 0.01 ≤ y ≤ 0.40, z = 1 - x - y, 0.95 ≤ a ≤ 1.05, 0 < b ≤ 0.05, 0 < c ≤ 0.05, 0 < d ≤ 0.05, 0 ≤ e ≤ 0.05, 0 < f ≤ 0.05; M is selected from one or more of magnesium, potassium, zinc, zirconium, titanium, strontium, cesium and calcium; A is selected from one or more of strontium, potassium and cesium. Compared with the prior art, by performing Na + 、Mg 2+ 、Zr 4+The bulk doping of multiple elements such as [element names] can significantly expand the layer spacing of the lithium-ion layer in the material structure, reduce the degree of cation mixing, and the fast ion conductor-like lithium silicate component formed by the reaction can improve the conductivity of lithium ions. Moreover, the silicon-oxygen bond in the lithium silicate component has strong stability, which can effectively reduce the volume change of the material during phase transformation and maintain a stable crystal structure even under deep de-lithiation conditions. Secondly, through surface coating, while removing residual alkali, a uniform and dense coating layer is formed, which can effectively inhibit the side reaction between the material surface and the electrolyte during charge and discharge, and improve the cycle stability of the material. Brief Description of the Drawings
[0030] Figure 1 This is the scanning electron microscope image of the ternary cathode material obtained in Example 1 of the present invention. Detailed Embodiments
[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0032] The present invention provides a ternary cathode material, and the chemical formula of the ternary cathode material is Li a Ni x Co y Mn z Si b Al c Na d M e A f O2; wherein, 0.10 ≤ x ≤ 0.99, 0.01 ≤ y ≤ 0.40, z = 1 - x - y, 0.95 ≤ a ≤ 1.05, 0 < b ≤ 0.05, 0 < c ≤ 0.05, 0 < d ≤ 0.05, 0 ≤ e ≤ 0.05, 0 < f ≤ 0.05; M is one or more of magnesium, potassium, zinc, zirconium, titanium, strontium, cesium, and calcium; A is one or more of strontium, potassium, and cesium.
[0033] Nickel plays a key role in increasing battery capacity in ternary materials. The more nickel content, the greater the capacity of the battery, which means that it can provide a longer driving range. In a specific embodiment provided by the present invention, optionally, x is 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 0.99 or a range between any two of the above values. Depending on x, the ternary positive electrode material can be divided into medium-low nickel positive electrode material and high nickel positive electrode material; when x≤0.6, the ternary positive electrode material is a medium-low nickel positive electrode material with better stability, but slightly inferior energy density; when x>0.6, the ternary positive electrode material is a high nickel positive electrode material with higher capacity.
[0034] In a specific embodiment provided by the present invention, 0.90≤x≤0.99, at this time the ternary positive electrode material is an ultra-high nickel positive electrode material; optionally, x is 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99 or a range between any two of the above values; in the embodiment provided by the present invention, x is specifically taken as 0.94 as an example for illustration.
[0035] Cobalt is mainly responsible for improving the stability of the battery and extending its service life in the positive electrode material. It can reduce the occupancy of the cationic mixture, stabilize the layered structure of the material, reduce the impedance value, and improve the conductivity, thereby improving the cycle and rate performance of the battery. However, too high a cobalt content will also lead to a decrease in actual capacity, so its proportion also needs to be precisely controlled. In a specific embodiment provided by the present invention, optionally, y is 0.01, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40 or a range between any two of the above values.
[0036] In a specific embodiment provided by the present invention, the ternary positive electrode material is an ultra-high nickel positive electrode material, 0.01≤y≤0.10; optionally, y is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10 or a range between any two of the above values.
[0037] In a specific embodiment provided by the present invention, optionally, a is 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, 1.05 or a range between any two of the above values.
[0038] In a specific embodiment provided by the present invention, optionally, b is 0.01, 0.02, 0.03, 0.04, 0.05 or a range between any two of the above values.
[0039] In a specific embodiment provided by the present invention, optionally, c is 0.01, 0.02, 0.03, 0.04, 0.05 or a range between any two of the above values.
[0040] In a specific embodiment provided by the present invention, optionally, d is 0.01, 0.02, 0.03, 0.04, 0.05 or a range between any two of the above values.
[0041] In a specific embodiment provided by the present invention, optionally, e is 0, 0.01, 0.02, 0.03, 0.04, 0.05 or a range between any two of the above values.
[0042] In a specific embodiment provided by the present invention, optionally, f is 0.01, 0.02, 0.03, 0.04, 0.05 or a range between any two of the above values.
[0043] In a specific embodiment provided by the present invention, the ternary cathode material comprises a core and a coating layer wrapped around the core; the chemical formula of the core is Li a Ni x Co y Mn z Si b Al c Na d M e O2; the coating layer is a calcined product of an inorganic compound containing A. Surface coating with the inorganic compound containing A can remove residual alkali while forming a uniform and dense coating layer, effectively inhibiting side reactions between the material surface and the electrolyte during charge and discharge, and improving the material's cycling stability. The inorganic compound containing A is preferably one or more of strontium hydroxide, potassium nitrate, and cesium phosphate.
[0044] In a specific embodiment provided by the present invention, the ternary positive electrode material is an ultra-high nickel positive electrode material, and the DSC decomposition temperature of the ternary positive electrode material is ≥245°C; the higher the DSC decomposition temperature, the better the thermal stability of the ternary positive electrode material.
[0045] In a specific embodiment provided by the present invention, the ternary positive electrode material is an ultra-high nickel positive electrode material, and the lithium-nickel intermixing value of the ternary positive electrode material is ≤3.0%. The lithium-nickel intermixing value of the ternary positive electrode material refers to the phenomenon in which the lithium ions and nickel ions in the ternary positive electrode material in a lithium-ion battery interchange their positions in the crystal structure. This phenomenon can lead to a decrease in battery performance, particularly a decrease in capacity and cycle stability. The lower the lithium-nickel intermixing value, the better the battery's energy and cycle stability.
[0046] The unit cell parameter c value reflects the interlayer structural characteristics of the ternary cathode material. If the c value is too low, the layered structure stability of the material is poor, which easily leads to cation mixing, affecting the conductivity and cycle performance of the material. A higher c value can increase the capacity of the material, but if the c value is too high, the nickel ion concentration in the lithium layer will increase, making it difficult for lithium to be deintercalated in the layered structure, thereby affecting the electrochemical performance. In a specific embodiment provided by the present invention, the ternary cathode material is an ultra-high nickel cathode material; the unit cell parameter c value of the ternary cathode material is ≥14.19, preferably 14.19≤c value≤14.21, and more preferably 14.193≤c value≤14.203.
[0047] D50 refers to the particle size at which the cumulative particle size distribution percentage of the sample reaches 50%. A smaller D50 value indicates a smaller particle size, which helps shorten the diffusion path of lithium ions and increase the migration rate of lithium ions, thereby improving the battery's charge and discharge rate and cycle stability. However, too small a particle size may also lead to an increase in specific surface area, increasing the probability of side reactions, thereby affecting the battery's cycle life and safety. In a specific embodiment provided by the present invention, the ternary positive electrode material is an ultra-high nickel positive electrode material; the D50 of the ternary positive electrode material is preferably 8.5-15μm; optionally, the D50 of the ternary positive electrode material is 8.5μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, or a range between any two of the above values. Within this range, the battery can have higher cycle stability and safety.
[0048] The present invention is to carry out Na + Mg 2+ 、Zr 4+ The bulk doping of multiple elements such as lithium ions can significantly expand the interlayer spacing of the lithium ion layer in the material structure and reduce the degree of cation mixing. The fast ion conductor lithium silicate component formed by the reaction can improve the conductivity of lithium ions. Moreover, the silicon-oxygen bond in the lithium silicate component has strong stability, which can effectively reduce the volume change of the material during phase change and maintain a stable crystal structure under deep delithiation conditions. Secondly, through surface coating, while removing residual alkali, a uniform and dense coating layer is formed, which can effectively inhibit the side reaction between the material surface and the electrolyte during charging and discharging, and improve the cycle stability of the material.
[0049] The present invention also provides a preparation method of the above-mentioned ternary positive electrode material, comprising the following steps: S1) mixing a ternary precursor, a lithium source and a primary additive to obtain a mixture A; the primary additive includes a silicate group; the primary additive includes at least two of the metal elements sodium, aluminum, magnesium, potassium, zinc, zirconium, titanium, strontium, cesium and calcium, and includes the metal elements sodium and aluminum; S2) sintering the mixture A at a high temperature in an oxidizing atmosphere, and crushing it to obtain a positive electrode material B; S3) mixing the positive electrode material B with a secondary additive to obtain a mixture C; the secondary additive includes one or more of the metal elements strontium, potassium and cesium; S4) sintering the mixture C at a low temperature in an oxidizing atmosphere, and sieving it to obtain a ternary positive electrode material.
[0050] The present invention has no particular limitation on the sources of all raw materials, and any commercially available raw materials may be used.
[0051] The ternary precursor, lithium source and primary additive are mixed to obtain a mixture A; the general formula of the ultra-high nickel precursor is preferably Ni x Co y Mn z(OH)2; wherein, 0.10≤x≤0.99, 0.01≤y≤0.40, z=1-xy; the x and y are the same as described above and will not be repeated here; the D50 of the ternary precursor is preferably 8.5-15μm; optionally, the D50 of the ternary precursor is 8.5μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm or a range between any two of the above values; the lithium source can be a lithium source well known to those skilled in the art without any special restrictions. In the present invention, it is preferably one or more of LiOH, LiOH·H2O and Li2CO3, more preferably LiOH·H2O; the element nickel in the ternary precursor , the molar ratio of the total molar number of cobalt and manganese to the lithium source is preferably 1: (1.00-1.10); an excess of lithium salt can compensate for the volatilization of lithium during high-temperature sintering; optionally, the molar ratio of the total molar number of elements nickel, cobalt and manganese in the ternary precursor to the lithium source is 1: 1.00, 1: 1.01, 1: 1.02, 1: 1.03, 1: 1.04, 1: 1.05, 1: 1.06, 1: 1.07, 1: 1.08, 1: 1.09, 1: 1.10 or a range between any two of the above values; the primary additive is preferably a nanomaterial, more preferably sodium silicate, potassium silicate, zinc silicate, zirconium silicate, calcium silicate, titanium silicate, magnesium silicate, strontium silicate, cesium silicate, magnesium calcium silicate, magnesium aluminum silicate , sodium aluminum silicate, sodium zirconium silicate, sodium titanate, lithium magnesium sodium silicate, lithium aluminum silicate, lithium magnesium silicate, sodium magnesium aluminum silicate and sodium potassium aluminum silicate; the addition amount of the primary additive is preferably 100-5000ppm of the mass of the ternary precursor; optionally, the addition amount of the primary additive is 100ppm, 200ppm, 500ppm, 800ppm, 1000ppm, 1200ppm, 1500ppm, 1800ppm, 2000ppm, 2200ppm, 2500ppm, 2800ppm, 3000ppm, 3200ppm, 3500ppm, 3800ppm, 4000ppm of the mass of the ternary precursor m, 4200ppm, 4500ppm, 4800ppm, 5000ppm or a range between any two of the above values; by doping a primary additive of a specific concentration, the interlayer spacing of the lithium ion layer in the material structure can be expanded, and the degree of cation mixing can be reduced. The fast ion conductor lithium silicate component formed by the reaction can improve the conductivity of lithium ions, and the silicon-oxygen bond in the lithium silicate component has strong stability, which can effectively reduce the volume change of the material during phase change and maintain a stable crystal structure under deep delithiation conditions; the mixing method is a method well known to those skilled in the art and is not particularly limited. In the present invention, a high-speed mixer is preferably used to make the raw material mixing more uniform.
[0052] The mixture A is sintered at high temperature in an oxidizing atmosphere and crushed to obtain a positive electrode material B; the oxidizing atmosphere is selected according to the type of the ternary precursor. When the ternary precursor is a medium-low nickel ternary precursor, that is, x≤0.6, the oxidizing atmosphere is preferably air; when the ternary precursor is a high nickel ternary precursor, that is, x>0.6, the mass concentration of oxygen in the oxidizing atmosphere is ≥95%, more preferably 95% to 99%; high-temperature sintering in a relatively high oxygen atmosphere can promote orderly arrangement of cations; optionally, the mass concentration of oxygen in the oxidizing atmosphere is 95%, 96%, 97%, 98%, 99% or a range between any two of the above values; the temperature of the high-temperature sintering is preferably 700°C to 900°C; optionally, the temperature of the high-temperature sintering is 700°C, 720°C, 730°C, 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, 800°C, 810°C, 820°C, 830°C, 840°C, 860°C, 870°C, 880°C, 890°C, 900°C, 900°C, 900°C, 900°C, 920°C, 920°C, 930°C, 9 , 750℃, 780℃, 790℃, 800℃, 810℃, 830℃, 850℃, 880℃, 890℃, 900℃ or the range between any two of the above values; the high temperature sintering time is preferably 10-20h; optionally, the high temperature sintering time is 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h or the range between any two of the above values; the heating rate of the high temperature sintering is preferably 1-5℃ / min; optionally, the heating rate of the high temperature sintering is 1℃ / min, 1.5℃ / min, 1.8℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min or the range between any two of the above values.
[0053] The positive electrode material B is mixed with a secondary additive to obtain a mixture C; the secondary additive is preferably one or more of strontium hydroxide, potassium nitrate and cesium phosphate; the amount of the secondary additive added is preferably 100 to 5000 ppm of the mass of the positive electrode material B; optionally, the amount of the secondary additive added is 100 ppm, 200 ppm, 500 ppm, 800 ppm, 1000 ppm, 1200 ppm, 1500 ppm, 1800 ppm, 2000 ppm, 2200 ppm, 2500 ppm, 2800 ppm, 3000 ppm, 3200 ppm, 3500 ppm, 3800 ppm, 4000 ppm, 4200 ppm, 4500 ppm, 4800 ppm, 5000 ppm or a range between any two of the above values, based on the mass of the positive electrode material B; the mixing method is a method well known to those skilled in the art and is not particularly limited. In the present invention, a high-speed mixer is preferably used. By coating the surface of the positive electrode material B with secondary additives, the residual alkali can be removed during the subsequent low-temperature sintering process, and a uniform and dense coating layer is formed, which can effectively inhibit the side reactions between the material surface and the electrolyte during charging and discharging, and improve the cycle stability of the material.
[0054] The mixture C is sintered at a low temperature in an oxidizing atmosphere and sieved to obtain a ternary positive electrode material; the oxidizing atmosphere is selected according to the type of the ternary precursor. When the ternary precursor is a medium-low nickel ternary precursor, that is, x≤0.6, the oxidizing atmosphere is preferably air; when the ternary precursor is a high nickel ternary precursor, that is, x>0.6, the mass concentration of oxygen in the oxidizing atmosphere is ≥95%, more preferably 95% to 99%; optionally, the mass concentration of oxygen in the oxidizing atmosphere is 95%, 96%, 97%, 98%, 99% or a range between any two of the above values; the temperature of the low temperature sintering is preferably 200°C to 650°C; optionally, the temperature of the low temperature sintering is 200°C, 260°C, 280°C, 300°C, 330°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C, 1300°C, 1400°C, 1500°C, 1600°C, 1700°C, 1800°C, 2000°C, 2100°C, 2200°C, 2300°C, 2400°C, 2500°C, 2600°C, 2800°C, 3000°C, 3 ... 0℃, 350℃, 380℃, 400℃, 450℃, 500℃, 550℃, 580℃, 600℃, 620℃, 650℃ or the range between any two of the above values; the time of the low temperature sintering is preferably 4 to 10h; optionally, the time of the low temperature sintering is 4h, 5h, 6h, 7h, 8h, 9h, 10h or the range between any two of the above values; the heating rate of the low temperature sintering is preferably 0.5 to 5℃ / min; optionally, the heating rate of the low temperature sintering is 0.5℃ / min, 1℃ / min, 1.5℃ / min, 1.8℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min or the range between any two of the above values.
[0055] The present invention also provides a lithium-ion battery comprising the above-mentioned ternary positive electrode material.
[0056] In the present invention, the ternary cathode material can be directly used as a cathode active material of a lithium-ion battery, and can also be used to prepare a cathode material of a lithium-ion battery.
[0057] In a specific embodiment provided by the present invention, the lithium ion battery includes a positive electrode sheet; the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer provided on at least one surface of the positive electrode current collector; the positive electrode active layer includes the above-mentioned ternary positive electrode material; the mass of the ternary positive electrode material is preferably 88% to 95% of the mass of the positive electrode active layer; optionally, the mass of the ternary positive electrode material is 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95% or a range between any two of the above values of the mass of the positive electrode active layer; the positive electrode active layer further includes a conductive agent; the conductive agent is a conductive agent well known to those skilled in the art and is not particularly limited. In the present invention, conductive SP, One or more of carbon nanotubes and graphene; the mass of the conductive agent is preferably 1% to 8% of the mass of the positive electrode active layer; optionally, the mass of the conductive agent is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8% of the mass of the positive electrode active layer or a range between any two of the above values; the positive electrode active layer also includes a binder; the binder is a binder well known to those skilled in the art and is not particularly limited. In the present invention, PVDF is preferably used; the mass of the binder is preferably 1% to 8% of the mass of the positive electrode active layer; optionally, the mass of the binder is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8% of the mass of the positive electrode active layer or a range between any two of the above values.
[0058] In a specific embodiment provided by the present invention, the lithium-ion battery further comprises a negative electrode sheet; the negative electrode sheet can be any negative electrode sheet well known to those skilled in the art without any special limitation, and is preferably a metal lithium sheet in the present invention.
[0059] In a specific embodiment provided by the present invention, the lithium-ion battery preferably further includes an electrolyte; the electrolyte includes a lithium salt and a solvent; the concentration of the lithium salt in the electrolyte is preferably 0.5-1.5 mol / L, more preferably 0.8-1.4 mol / L, and even more preferably 1-1.2 mol / L; the lithium salt is a lithium salt well known to those skilled in the art, and there is no special limitation. In the embodiments provided by the present invention, LiPF6 is used as an example for illustration; the solvent is a solvent well known to those skilled in the art, and there is no special limitation. In the embodiments provided by the present invention, ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) with a volume ratio of 1:1:1 are used as an example for illustration.
[0060] In order to further illustrate the present invention, a ternary positive electrode material, a preparation method thereof and applications provided by the present invention are described in detail below in conjunction with embodiments.
[0061] The reagents used in the following examples are all commercially available.
[0062] Example 1
[0063] 1.1 Ni with D50 = 10 μm 0.94 Co 0.04 Mn 0.02 (OH)2 precursor, LiOH·H2O and nano-sodium magnesium aluminum silicate are mixed evenly, with a molar ratio of LiOH·H2O:precursor = 1.02, and an addition amount of nano-sodium magnesium aluminum silicate is 1000ppm of the precursor mass, to obtain mixture A after mixing; mixture A is sintered at a high temperature of 790°C, a heating rate of 4.0°C / min, a sintering time of 16h, a sintering atmosphere of oxygen, and an oxygen concentration of 95%; and positive electrode material B is obtained after crushing.
[0064] 1.2 The positive electrode material B and potassium nitrate are mixed to obtain a mixture C, where the amount of potassium nitrate added is 1000 ppm based on the mass of the positive electrode material B; the mixture C is sintered at a low temperature of 260°C, a heating rate of 3.5°C / min, a sintering time of 10 h, an oxygen atmosphere with an oxygen concentration of 95%, and sieved to obtain a ternary positive electrode material.
[0065] The ternary cathode material obtained in Example 1 was analyzed using an electron scanning microscope, and the scanning electron microscope image thereof was obtained as follows: Figure 1 shown.
[0066] Example 2
[0067] 2.1 Ni with D50=8.5μm 0.94 Co 0.04 Mn 0.02 (OH)2 precursor, LiOH·H2O, nano-sodium silicate, nano-aluminum silicate and nano-titanium silicate are mixed evenly, and the molar ratio is LiOH·H2O:precursor = 1.03, the addition amount of nano-sodium silicate is 1000ppm of the precursor mass, the addition amount of nano-aluminum silicate is 500ppm of the precursor mass, and the addition amount of nano-titanium silicate is 500ppm of the precursor mass, and the mixture A is obtained after mixing; the mixture A is sintered at a high temperature, the sintering temperature is 790°C, the heating rate is 3.0°C / min, the sintering time is 13h, the sintering atmosphere is oxygen, and the oxygen concentration is 96%; and the positive electrode material B is obtained after crushing.
[0068] 2.2 The positive electrode material B and cesium phosphate are mixed to obtain a mixture C, where the amount of cesium phosphate added is 1500ppm by mass of the positive electrode material B; the mixture C is sintered at a low temperature of 330°C, a heating rate of 0.5°C / min, a sintering time of 8h, an oxygen atmosphere with an oxygen concentration of 96%, and after screening, a ternary positive electrode material is obtained.
[0069] Example 3
[0070] 3.1 Ni with D50 = 12 μm 0.94 Co 0.04 Mn 0.02 (OH)2 precursor, LiOH·H2O, lithium aluminum silicate and sodium zirconium silicate are mixed evenly, with a molar ratio of LiOH·H2O:precursor = 1.04, an addition amount of nano lithium aluminum silicate is 1200ppm of the precursor mass, and an addition amount of nano sodium zirconium silicate is 1000ppm of the precursor mass, to obtain mixture A after mixing; mixture A is sintered at a high temperature of 830°C, a heating rate of 2.0°C / min, a sintering time of 11h, a sintering atmosphere of oxygen, and an oxygen concentration of 97%; and positive electrode material B is obtained after crushing.
[0071] 3.2 The positive electrode material B and strontium hydroxide are mixed to obtain a mixture C, where the amount of strontium hydroxide added is 1500ppm by mass of the positive electrode material B; the mixture C is sintered at a low temperature, with a sintering temperature of 600°C, a heating rate of 5°C / min, a sintering time of 5h, a sintering atmosphere of oxygen, and an oxygen concentration of 97%. After screening, the ternary positive electrode material can be obtained.
[0072] Example 4
[0073] 4.1 Ni with D50 = 14 μm 0.94 Co 0.04 Mn 0.02 (OH)2 precursor, LiOH·H2O and nano-potassium sodium aluminum silicate are mixed evenly, with a molar ratio of LiOH·H2O:precursor = 1.04, and an addition amount of nano-potassium sodium aluminum silicate is 1500ppm based on the mass of the precursor, to obtain mixture A after mixing; mixture A is sintered at a high temperature of 780°C, a heating rate of 1.8°C / min, a sintering time of 18h, a sintering atmosphere of oxygen, and an oxygen concentration of 98%; and positive electrode material B is obtained after crushing.
[0074] 4.2 The positive electrode material B and potassium nitrate are mixed to obtain a mixture C, where the amount of potassium nitrate added is 2000ppm based on the mass of the positive electrode material B; the mixture C is subjected to low-temperature sintering. The material C is subjected to low-temperature sintering at a sintering temperature of 550°C, a heating rate of 5°C / min, a sintering time of 5h, and an oxygen atmosphere with an oxygen concentration of 98%. After screening, the ternary positive electrode material can be obtained.
[0075] Example 5
[0076] 5.1 Ni with D50 = 10 μm 0.94 Co 0.04 Mn 0.02(OH)2 precursor, LiOH·H2O, nano-sodium magnesium aluminum silicate and nano-sodium potassium aluminum silicate are mixed evenly, with a molar ratio of LiOH·H2O:precursor = 1.05, an addition amount of nano-sodium magnesium aluminum silicate is 800ppm by mass of the precursor, and an addition amount of nano-sodium potassium aluminum silicate is 1100ppm by mass of the precursor, to obtain a mixture A after mixing; the mixture A is sintered at a high temperature of 810°C, a heating rate of 3.5°C / min, a sintering time of 18h, a sintering atmosphere of oxygen, and an oxygen concentration of 99%; and the positive electrode material B is obtained after crushing.
[0077] 5.2 The positive electrode material B and strontium hydroxide are mixed to obtain a mixture C, wherein the amount of strontium hydroxide added is 3000ppm by mass of the positive electrode material B; the mixture C is subjected to low-temperature sintering. The material C is subjected to low-temperature sintering. The sintering temperature is 380°C, the heating rate is 3°C / min, the sintering time is 9h, the sintering atmosphere is oxygen, and the oxygen concentration is 99%. After screening, the ternary positive electrode material can be obtained.
[0078] Comparative Example 1
[0079] This comparative example provides a method for preparing a ternary positive electrode material. The difference between this comparative example and Example 1 is that nano-sodium magnesium aluminum silicate is not added in step (1), and the remaining preparation methods and parameters are consistent with Example 1 to obtain a ternary positive electrode material.
[0080] Comparative Example 2
[0081] This comparative example provides a method for preparing a ternary positive electrode material. The difference between this comparative example and Example 1 is that step (2) is not performed, and the remaining preparation methods and parameters are consistent with Example 1 to obtain a ternary positive electrode material.
[0082] Comparative Example 3
[0083] This comparative example provides a method for preparing a ternary positive electrode material. The difference between this comparative example and Example 1 is that nano-sodium magnesium aluminum silicate is not added in step (1), and potassium nitrate is not added to the solution in step (2). The remaining preparation methods and parameters are consistent with Example 1 to obtain a ternary positive electrode material.
[0084] Comparative Example 4
[0085] This comparative example provides a method for preparing a ternary positive electrode material. The difference between this comparative example and Example 1 is that the addition amount of nano-sodium magnesium aluminum silicate in step (1) is changed to 6000ppm of the precursor mass, and the remaining preparation methods and parameters are consistent with Example 1 to obtain a ternary positive electrode material.
[0086] Comparative Example 5
[0087] This comparative example provides a method for preparing a ternary positive electrode material. The difference between this comparative example and Example 1 is that the amount of potassium nitrate added in step (2) is changed to 6000 ppm of the mass of the positive electrode material B, and the remaining preparation methods and parameters are consistent with Example 1 to obtain a ternary positive electrode material.
[0088] Comparative Example 6
[0089] This comparative example provides a method for preparing a ternary positive electrode material. The difference between this comparative example and Example 1 is that in step (1), the nano-sodium magnesium aluminum silicate is replaced with 500 ppm aluminum oxide, 1000 ppm magnesium oxide, and 1000 ppm sodium hydroxide. The remaining preparation methods and parameters are consistent with Example 1 to obtain a ternary positive electrode material.
[0090] Comparative Example 7
[0091] This comparative example provides a method for preparing a ternary positive electrode material. The difference between this comparative example and Example 1 is that potassium nitrate in step (2) is replaced by aluminum oxide, and the remaining preparation methods and parameters are consistent with Example 1 to obtain a ternary positive electrode material.
[0092] The ternary cathode materials obtained in the examples and comparative examples were subjected to DSC, XRD, and electrical performance tests. The test results are shown in Table 1.
[0093] The preparation method of the button battery is as follows: CR2032 button batteries are assembled in a glove box, and the ternary positive electrode materials obtained in Examples 1 to 5 and Comparative Examples 1 to 7 are used as positive electrode materials. The positive electrode material, conductive SP, and binder PVDF are weighed in a mass ratio of 90:5:5, and NMP solution is added and dispersed and stirred for 2 hours to mix evenly. The slurry is prepared and coated on aluminum foil, and then cut into pole pieces with a diameter of 14 mm, and the coating amount is 12 mg / cm 2 , compaction 3.4g / cm 3 The lithium metal sheet serves as the negative electrode, Celgard 2400 as the separator, and the electrolyte contains 1.0 mol / L LiPF6 in a 1:1:1 ratio of EC:DMC:EMC. A CR2032 button cell is assembled in the following order: negative electrode shell, positive electrode sheet, electrolyte, separator, electrolyte, lithium sheet, and positive electrode shell. A button cell sealer is used to complete the production of a ternary cathode material lithium-ion battery.
[0094] DSC test: After charging the assembled lithium-ion battery to 4.3V (0.1C), the electrode was disassembled from the buckle battery, cleaned with DMC, and dried at 60℃ for 30min. Then, DSC test was performed in the temperature range of 0-400℃ and the heating rate of 10℃ / min. The test results are shown in Table 1.
[0095] XRD test: light source: Cu target Kα radiation, tube voltage / current: 40 kV and 30 mA, angle range: 10° to 90°, rate: 5° / min, fixed step size: 0.02°.
[0096] Electrochemical performance test: The assembled lithium-ion battery was subjected to electrochemical performance test in the range of 2.5 to 4.3 V (0.1C formation, 0.5C cycle). The test results are shown in Table 1.
[0097] Table 1 Test data corresponding to samples of Examples 1 to 5 and Comparative Examples 1 to 5
[0098]
[0099]
[0100] It can be seen from Table 1 that, compared with Comparative Examples 1 to 5, the ternary positive electrode materials prepared in Examples 1 to 5 all have higher DSC peak temperatures, lower lithium-nickel mixing values, and higher unit cell parameters c, indicating that the ternary positive electrode materials provided by the present invention have stronger thermal stability, lower degree of cation mixing, and larger interlayer spacing of lithium ion layers in the material structure. Secondly, the ternary positive electrode materials prepared in Examples 1 to 5 have higher discharge specific capacity, cycle retention rate, and lower cycle DCR growth, indicating that the ternary positive electrode materials provided by the present invention maintain structural stability without losing capacity, thereby achieving better cycle stability.
[0101] As shown in Table 1, while the ternary cathode materials prepared using Comparative Examples 4-5 exhibit higher DSC peak temperatures compared to Examples 1-5, their corresponding sample capacities and cycling performance are inferior, indicating that the presence of primary or secondary additives outside their reasonable applicable ranges can affect the electrochemical performance of the ultra-high nickel cathode materials. Similarly, the ternary cathode materials prepared using Comparative Examples 6-7 also failed to achieve the same performance levels as Examples 1-5 in all respects.
[0102] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.
Claims
1. A ternary cathode material, characterized in that: The chemical formula of the ternary cathode material is Li a Ni x Co y Mn z Si b Al c Na d M e A f O2; wherein, 0.10 ≤ x ≤ 0.99, 0.01 ≤ y ≤ 0.40, z = 1 - x - y, 0.95 ≤ a ≤ 1.05, 0 < b ≤ 0.05, 0 < c ≤ 0.05, 0 < d ≤ 0.05, 0 ≤ e ≤ 0.05, 0 < f ≤ 0.05; M is selected from one or more of magnesium, potassium, zinc, zirconium, titanium, strontium, cesium and calcium; A is selected from one or more of strontium, potassium and cesium.
2. The ternary cathode material according to claim 1, characterized in that The ternary cathode material comprises a core and a coating layer wrapped around the core; the chemical formula of the core is Li a Ni x Co y Mn z Si b Al c Na d M e O2; the coating layer is a calcined product of an inorganic compound containing A.
3. The ternary cathode material according to claim 1 or 2, characterized in that: 0.90≤x≤0.99, 0.01≤y≤0.
10.
4. The ternary cathode material according to claim 3, characterized in that The DSC decomposition temperature of the ternary cathode material is ≥245°C; And / or, the lithium-nickel mixing value of the ternary positive electrode material is ≤3.0%; And / or, the unit cell parameter c value of the ternary cathode material is ≥14.19; And / or, the D50 of the ternary positive electrode material is 8.5 to 15 μm.
5. A method for preparing the ternary cathode material according to claim 1, characterized in that: The following steps are involved: S1) mixing a ternary precursor, a lithium source, and a primary additive to obtain a mixture A; wherein the primary additive comprises a silicate group; and the primary additive comprises at least two of the metal elements sodium, aluminum, magnesium, potassium, zinc, zirconium, titanium, strontium, cesium, and calcium, and includes the metal elements sodium and aluminum; S2) sintering the mixture A at a high temperature in an oxidizing atmosphere and crushing the mixture to obtain a positive electrode material B; S3) mixing the positive electrode material B with a secondary additive to obtain a mixture C; the secondary additive comprises one or more of the metal elements strontium, potassium and cesium; S4) sintering the mixture C at a low temperature in an oxidizing atmosphere and sieving to obtain a ternary positive electrode material.
6. The preparation method according to claim 5, characterized in that The general formula of the ternary precursor is Ni x Co y Mn z (OH)2; wherein, 0.10≤x≤0.99, 0.01≤y≤0.40, z=1-xy; And / or, the lithium source is selected from one or more of LiOH, LiOH·H2O and Li2CO3.
7. The preparation method according to claim 5, characterized in that The primary additive is selected from one or more of sodium silicate, potassium silicate, zinc silicate, zirconium silicate, calcium silicate, titanium silicate, magnesium silicate, strontium silicate, cesium silicate, calcium magnesium silicate, magnesium aluminum silicate, sodium aluminum silicate, sodium zirconium silicate, sodium titanate silicate, sodium magnesium lithium silicate, lithium aluminum silicate, lithium magnesium silicate, sodium magnesium aluminum silicate and potassium sodium aluminum silicate; And / or, the secondary additive is selected from one or more of strontium hydroxide, potassium nitrate and cesium phosphate.
8. The preparation method according to claim 5, characterized in that The molar ratio of the total moles of nickel, cobalt and manganese in the ternary precursor to the lithium source is 1: (1.00-1.10); and / or, the amount of the primary additive added is 100 to 5000 ppm of the mass of the ternary precursor; And / or, the added amount of the secondary additive is 100 to 5000 ppm of the mass of the positive electrode material B.
9. The preparation method according to claim 5, characterized in that The temperature of the high-temperature sintering in step S2) is 700°C to 900°C; the time of the high-temperature sintering is 10 to 20 hours; and the heating rate of the high-temperature sintering is 1 to 5°C / min; In the step S4), the temperature of the low-temperature sintering is 200° C. to 650° C.; the time of the low-temperature sintering is 4 to 10 hours; and the heating rate of the low-temperature sintering is 0.5 to 5° C. / min.
10. A lithium ion battery, characterized in that: The invention comprises the ternary positive electrode material according to any one of claims 1 to 4 or the ternary positive electrode material prepared by the preparation method according to any one of claims 5 to 9.