Single-crystal ternary positive electrode material, preparation method therefor, positive electrode sheet, and battery

Abstract

The present description belongs to the technical field of battery materials. Disclosed are a single-crystal ternary positive electrode material, a preparation method therefor, a positive electrode sheet and a battery. The apparent factor of the single-crystal ternary positive electrode material is [Formula 1], wherein 1.1≤Z≤3, x=D90 / D10, 2≤x≤5; S(D90) is the number averaged circularity, the total number of target particles is n, and the number averaged circularity is defined as the sum of circularity values of all of the target particles divided by n. The area and circumference corresponding to a two-dimensional projection image of a single target particle are respectively S1 and l1, the circumference of a circle having the area S1 is l2}, and the circularity = l2 / l1. The D10' is the corresponding particle size of a material obtained by compacting the single-crystal ternary positive electrode material at 200 MPa, D10 does not exceed 2.4 μm, and D10' does not exceed 2.3 μm. The single-crystal ternary positive electrode material has smooth surfaces and rounded edges, which are beneficial for fabricating batteries having excellent electrochemical properties.

Description

Single-crystal ternary positive electrode material, preparation method thereof, positive electrode sheet and battery

[0001] Cross-reference to Related Applications

[0002] This application claims priority to the Chinese patent application No. 202410651224.2, filed on May 24, 2024, entitled "Single-crystal ternary positive electrode material, preparation method thereof, positive electrode sheet and battery", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of battery materials, in particular, to a single-crystal ternary positive electrode material, a preparation method thereof, a positive electrode sheet and a battery. BACKGROUND

[0004] Currently, the ternary positive electrode material is usually a polycrystalline secondary particle formed by agglomeration of nanoscale primary particles. During the charge and discharge cycle, the unit cell volume of the primary particles changes, resulting in anisotropic stress distribution within the secondary particles, which in turn causes intergranular cracks in the polycrystalline secondary particles, and even leads to the fragmentation of the polycrystalline particles. On the other hand, the preparation of the positive electrode sheet requires rolling, and the agglomerated polycrystalline secondary particles are easily broken, which affects the cycle life of the battery and restricts its commercial application.

[0005] The single-crystal ternary positive electrode material is composed of individual micron-sized particles, which has high mechanical strength and is not easily broken during the electrode sheet rolling process. Moreover, it does not produce intergranular cracks during the charge and discharge cycle, and has superior cycle stability. It is a high-performance positive electrode material that is expected to partially replace polycrystalline ternary positive electrode materials.

[0006] The conventional preparation method of single-crystal materials usually involves mixing hydroxide precursor secondary particles with a lithium source, followed by high-temperature sintering and then airflow crushing. However, this process forcibly breaks the agglomerated particles, resulting in sharp edges and corners. These sharp edges and corners can cause at least one of the following problems:

[0007] (1) During the preparation of the battery electrode, it can cause severe wear to the equipment, shorten the service life of the equipment accessories, and greatly increase the manufacturing cost of the battery;

[0008] (2) During the rolling process of the electrode sheet preparation, particles with sharp edges and corners are more likely to break, leading to delamination of the single crystals and surface defects, and forming more fine powder particles;

[0009] (3) The sharp edges and corners can cause uneven charge and discharge of the material during the battery charge and discharge process, resulting in strong polarization, and even particle fragmentation due to stress during the cycle process, leading to rapid degradation of the battery life.

[0010] (4) When the single crystal material is surface-coated, sharp corners are difficult to be completely coated, affecting the coating effect, so that the cycle performance cannot be improved.

[0011] In view of this, the present disclosure is proposed.

[0012] SUMMARY

[0013] The purpose of the present disclosure includes providing a single crystal ternary positive electrode material, a preparation method thereof, a positive electrode sheet and a battery to solve or improve at least one of the above technical problems.

[0014] The present disclosure can be achieved as follows:

[0015] In a first aspect, the present disclosure provides a single crystal ternary positive electrode material, wherein the apparent factor of the single crystal ternary positive electrode material is 1.1-3.0. The apparent factor of the single crystal ternary positive electrode material is 1.1-3.0.

[0016] wherein x=D 90 / D 10 , 2≤x≤5; D 90 is the particle size corresponding to the cumulative particle size distribution based on volume of the single crystal ternary positive electrode material reaching 90%, D 10 is the particle size corresponding to the cumulative particle size distribution based on volume of the single crystal ternary positive electrode material reaching 10%; the D 10 of the single crystal ternary positive electrode material is not more than 2.4 μm.

[0017] S(D 90 ) is the number average circularity, which is equal to the sum of the circularities of all target particles contained in the single crystal ternary positive electrode material divided by n; the circularity Q = l2 / l1, wherein S1 and l1 are defined as the area and the circumference of the two-dimensional projection diagram of a single target particle, l2 is defined as the circumference of a circle with the area S1, the target particle is defined as a single crystal ternary positive electrode material particle with a particle size greater than or equal to D 90 , n is the total number of target particles contained in the single crystal ternary positive electrode material.

[0018] H is the hardness, wherein D 10 ' is the particle size corresponding to the cumulative particle size distribution based on volume of the pressed material reaching 10%, the pressed material is the material obtained after the single crystal ternary positive electrode material is pressed using a pressure of 200 MPa; the D 10 ' of the single crystal ternary positive electrode material is not more than 2.3 μm.

[0019] In an optional embodiment, the single crystal ternary positive electrode material comprises at least one of the following features:

[0020] Feature one: D of the single-crystal ternary cathode material is not more than 8.6 μm; 90 not more than 8.6 μm;

[0021] Feature two: H of the single-crystal ternary cathode material is not less than 80%;

[0022] Feature three: S(D 90 ) of the single-crystal ternary cathode material is not more than 0.9.

[0023] In an optional embodiment, the apparent factor of the single-crystal ternary cathode material is 1.1634-2.9571;

[0024] and / or, x of the single-crystal ternary cathode material is 2.36-3.88;

[0025] and / or, D 90 of the single-crystal ternary cathode material is 5.01 μm-8.56 μm;

[0026] and / or, D 10 of the single-crystal ternary cathode material is 1.81 μm-2.34 μm;

[0027] and / or, H of the single-crystal ternary cathode material is 81%-96%;

[0028] and / or, S(D 90 ) of the single-crystal ternary cathode material is 0.68-0.87;

[0029] and / or, D 10 ’ of the single-crystal ternary cathode material is 1.57 μm-2.25 μm.

[0030] In an optional embodiment, the single-crystal ternary cathode material further comprises at least one of the following features:

[0031] Feature four: the particle size of the single-crystal ternary cathode material is not more than 20 μm;

[0032] Feature five: the general formula of the single-crystal ternary cathode material is Li d Ni a Co b M c M’ 1-a-b-c O2, wherein, 0.95≤d<1.1, a>0, b>0, c>0, 0.95≤(a+b+c)≤1; M comprises at least one of Al and Mn, M’ comprises at least one of a doping element and a coating element, the doping element and the coating element are independently selected from at least one of Zr, Sr, Mo, Ba, W, B, Ti, Mg, Li, C, F, Si, Ca, Cu, La, P, Ce, Bi, In, Nb and Y.

[0033] Feature six: in the single-crystal ternary cathode material, the cell parameter c and the cell parameter a satisfy c / a≥4.899;

[0034] Feature seven: the (003) crystal face diffraction peak intensity I (003) and the (104) crystal face diffraction peak intensity I (104) satisfy: I (003) / I (104) ≥1.51;

[0035] Feature eight: the surface roughness Ra of the electrode sheet corresponding to the single-crystal ternary cathode material is not more than 2.20 μm.

[0036] In an optional embodiment, the doping reagent for providing the doping element includes at least one of the oxides, fluorides, carbonates, hydroxides, nitrides, borides and nitrates corresponding to the doping element;

[0037] And / or, the coating reagent for providing the coating element includes at least one of the oxides, fluorides, carbonates, hydroxides, nitrides, borides and nitrates corresponding to the coating element.

[0038] In an optional embodiment, the surface roughness Ra of the electrode sheet corresponding to the single-crystal ternary cathode material is 0.86 μm to 2.12 μm.

[0039] In a second aspect, the disclosure provides a preparation method of the single-crystal ternary cathode material according to any one of the preceding embodiments, including the following steps:

[0040] mixing the precursor of the single-crystal ternary cathode material with a first lithium source and then performing first calcination to obtain a first mixture;

[0041] rapidly transferring the first mixture to water under a high-temperature state and combining with stirring to achieve first crushing to obtain a second mixture;

[0042] mixing the second mixture with a second lithium source and then performing second calcination to obtain a third mixture;

[0043] performing second crushing on the third mixture to obtain a fourth mixture.

[0044] In an optional embodiment, the preparation of the first mixture includes at least one of the following features:

[0045] Feature 1: the type of the precursor of the single-crystal ternary cathode material is a hydroxide precursor;

[0046] Feature 2: the ratio of the total mole amount of the transition metal elements in the precursor of the single-crystal ternary cathode material to the mole amount of lithium elements in the first lithium source is 1:0.4 to 1:0.7;

[0047] Feature 3: the temperature of the first calcination is 650-750℃;

[0048] Feature 4: the time of the first calcination is 1-3h;

[0049] Feature 5: the first calcination is performed in an oxygen-containing atmosphere.

[0050] In an optional embodiment, the precursor of the single-crystal ternary cathode material comprises a nickel-cobalt-manganese hydroxide or a nickel-cobalt-aluminum hydroxide.

[0051] In an optional embodiment, the first crushing comprises at least one of the following features:

[0052] Feature 6: the first crushing is achieved by thermal expansion and cold contraction effect;

[0053] Feature 7: the temperature of the water used for the first crushing is greater than 0℃ and not more than 50℃;

[0054] Feature 8: the stirring speed of the first crushing is 100-200rpm;

[0055] Feature 9: the stirring time of the first crushing is 5-20min;

[0056] and / or, the second crushing is performed by using an air flow crushing method.

[0057] In an optional embodiment, the transfer time of the first mixture from the high-temperature state to the water is not more than 30min.

[0058] In an optional embodiment, the preparation of the third mixture comprises at least one of the following features:

[0059] Feature 10: the ratio of the total moles of lithium in the first lithium source and the second lithium source to the total moles of transition metal elements in the second mixture is 1.05:1 to 1.1:1;

[0060] Feature 11: the temperature of the second calcination is 800-950℃;

[0061] Feature 12: the time of the second calcination is 4-6h;

[0062] Feature 13: the second calcination is performed in an oxygen-containing atmosphere.

[0063] In an optional embodiment, when the single-crystal ternary cathode material contains a doping element, the precursor of the single-crystal ternary cathode material, the first lithium source, and a doping reagent for providing the doping element are mixed and then subjected to the first calcination; or, the second mixture, the second lithium source, and a doping reagent for providing the doping element are mixed and then subjected to the second calcination.

[0064] Or, when the single-crystal ternary cathode material contains a coating element, the preparation method further comprises: mixing the fourth mixture with a coating reagent for providing the coating element and then performing a third calcination.

[0065] In optional embodiments, the oxygen content in the oxygen-containing atmosphere in the first calcination is ≥20wt%; and / or, the second calcination is performed in an oxygen-containing atmosphere with an oxygen content ≥20wt%; and / or, the third calcination is performed in an oxygen-containing atmosphere with an oxygen content ≥20wt%. In a third aspect, the disclosure provides a positive electrode tab, wherein the active material in the positive electrode tab comprises the single-crystal ternary cathode material of any one of the preceding embodiments.

[0066] In optional embodiments, the positive electrode tab has at least one of the following characteristics:

[0067] Feature nine: the first discharge specific capacity of the positive electrode tab corresponding to 0.1C is not less than 171.0mAh / g;

[0068] Feature ten: the capacity retention rate of the positive electrode tab corresponding to 0.1C after 50 cycles is not less than 89.2%;

[0069] Feature eleven: the first discharge specific capacity of the positive electrode tab corresponding to 1C is not less than 148.3mAh / g;

[0070] Feature twelve: the first discharge specific capacity of the positive electrode tab corresponding to 5C is not less than 125.8mAh / g.

[0071] In a fourth aspect, the disclosure provides a battery cell containing the positive electrode tab of the preceding embodiments.

[0072] In a fifth aspect, the disclosure provides a battery containing the battery cell of the preceding embodiments.

[0073] In a sixth aspect, the disclosure provides an electric device containing the battery cell or battery of the preceding embodiments.

[0074] In optional embodiments, the electric device comprises a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric automobile, a ship or a spacecraft.

[0075] The beneficial effects of the disclosure include:

[0076] The disclosure proposes a single-crystal ternary cathode material with a specific range of apparent factors, which has the characteristics of smooth surface and rounded corners, which is beneficial to make the electrode with it as a positive electrode material have higher specific capacity, rate performance and cycle performance. The corresponding single-crystal ternary cathode material preparation method is simple, easy to operate, and can be produced industrially. The above-mentioned single-crystal ternary cathode material can further prepare a battery with excellent electrochemical performance and an electric device, etc. Attached Figure Description

[0077] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this disclosure and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0078] Figure 1 shows the XRD patterns of the single-crystal ternary cathode materials obtained in Examples 1-5 and Comparative Example 1.

[0079] Figure 2 shows the SEM images of the single-crystal ternary cathode materials obtained in Examples 1, 10 and Comparative Example 1 of the experimental examples;

[0080] Figure 3 shows the relationship between the apparent factor of the single-crystal ternary cathode materials obtained in Examples 1-13 and Comparative Examples 1-4 and the surface roughness of the corresponding electrode sheets of each single-crystal ternary cathode material. Detailed Implementation

[0081] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions in the embodiments of this disclosure will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0082] The following is a detailed description of the single-crystal ternary cathode material, its preparation method, cathode sheet, and battery provided in this disclosure.

[0083] This disclosure proposes a single-crystal ternary cathode material, the apparent factor of which is... The apparent factor of single-crystal ternary cathode materials ranges from 1.1 to 3.0.

[0084] This disclosure proposes a single-crystal ternary cathode material with a specific range of apparent factors. This single-crystal ternary cathode material has the characteristics of smooth surface and rounded edges, which is beneficial to enable electrodes and batteries using it as cathode material to have high specific capacity, rate performance and cycle performance.

[0085] The apparent factor combines multiple apparent indexes (such as particle size distribution, particle shape and hardness) of the single-crystal ternary cathode material, and the apparent indexes are related to the tap density of the single-crystal ternary cathode material, and the tap density of the single-crystal ternary cathode material is closely related to the surface roughness and electrochemical performance of the electrode sheet containing the single-crystal ternary cathode material. Generally, the greater the tap density of the cathode material, the better the electrochemical performance of the corresponding electrode; in addition, the surface roughness of the electrode sheet is one aspect of the electrode performance, and the smaller the surface roughness, the better the cycle performance of the electrode. Therefore, the apparent factor can be used to predict part of the performance of the cathode material and the electrode. For example, the apparent factor defined in the present disclosure is linearly and positively correlated with the surface roughness of the electrode sheet containing the single-crystal ternary cathode material.

[0086] The apparent factor of the single-crystal ternary cathode material is 1.1-3.0, and in some optional modes, the apparent factor of the single-crystal ternary cathode material can exemplarily be 1.1634-2.9571, such as 1.1634, 1.1959, 1.3481, 1.5992, 1.6826, 1.7659, 1.7735, 1.7978, 1.9834, 2.1570, 2.2532, 2.5193, 2.8008 or 2.9571, etc. The single-crystal ternary cathode material with the apparent factor in the above range can enable the battery using the same as the cathode material to obtain better comprehensive performance (including specific capacity, rate performance and cycle performance, etc.).

[0087] x=D 90 / D 10 , 2≤x≤5, that is, x can be any value in the range of 2-5, such as 2, 2.5, 3, 3.5, 4, 4.5 or 5, etc. In some optional modes, the D 90 / D 10 value of the single-crystal ternary cathode material is 2.36-3.88, such as 2.36, 3.22, 3.35, 3.55, 3.67 or 3.88, etc.

[0088] D 90 is the particle size corresponding to the 90% of the cumulative particle size distribution by volume of the single-crystal ternary cathode material, and D 10 is the particle size corresponding to the 10% of the cumulative particle size distribution by volume of the single-crystal ternary cathode material.

[0089] In some optional modes, the D 90 of the single-crystal ternary cathode material is not more than 8.6 μm, and can exemplarily be 5.01 μm-8.56 μm, such as 5.01 μm, 5.92 μm, 6.09 μm, 6.59 μm, 6.82 μm, 7.39 μm, 7.89 μm or 8.56 μm, etc.

[0090] In some alternative manners, the single-crystal ternary cathode material has a S(D 10 of no more than 2.4 μm, and exemplarily can be 1.81 μm to 2.34 μm, such as 1.81, 1.84, 1.92, 1.96, 2.02, 2.11, 2.15, or 2.34, etc.

[0091] S(D 90 ) is a number average circularity, and the target particle is defined as a single-crystal ternary cathode material particle having a particle size of greater than or equal to D 90 , and the total number of the target particles contained in the single-crystal ternary cathode material is n, and the number average circularity is equal to the sum of the circularities of all the target particles contained in the single-crystal ternary cathode material divided by n.

[0092] The area and the perimeter of the two-dimensional projection map of the single-particle target particle are defined as S1 and l1, respectively, and the circumference of a circle having an area S1 is defined as l2, and the circularity Q = l2 / l1.

[0093] In some alternative manners, the single-crystal ternary cathode material has a S(D 90 of no more than 0.9, and exemplarily can be 0.68 to 0.87, such as 0.68, 0.70, 0.71, 0.73, 0.77, 0.79, 0.80, 0.82, 0.84, or 0.87, etc.

[0094] The single-crystal ternary cathode material having the above D 90 , D 10 , and S(D 90 ) ranges is beneficial to improve the tap density of the electrode containing the single-crystal ternary cathode material, reduce the surface roughness of the electrode sheet, and improve the electrochemical performance of the electrode and the corresponding battery, based on the grading filling effect and the diverse contact types (such as point, line, and surface interworking) of the irregularly shaped powder. 90 / D 10 can reflect the particle size distribution width of the powder, and the powder having the D 90 , D 10 has a grading filling effect, which can improve the tap density; the powder in the above S(D 90 ) range has an irregular shape, and thus has diverse contact types (such as point, line, and surface interworking), which is further beneficial to improve the contact of the powder and thus improve the tap density; and the higher tap density is beneficial to improve the electrochemical performance of the electrode sheet.

[0095] H is the hardness, wherein D 10 ' is the particle size corresponding to the cumulative particle size distribution of 10% by volume of the pressed material, and the pressed material is the material obtained after the single-crystal ternary cathode material is pressed using a pressure of 200 MPa.

[0096] In some optional modes, the D of the single-crystal ternary cathode material is not more than 2.3 μm, and exemplarily can be 1.57 μm to 2.25 μm, such as 1.57 μm, 1.69 μm, 1.72 μm, 1.74 μm, 1.77 μm, 1.82 μm, 1.92 μm or 2.25 μm, etc. 10 ’ not more than 2.3 μm, exemplarily can be 1.57 μm to 2.25 μm, such as 1.57 μm, 1.69 μm, 1.72 μm, 1.74 μm, 1.77 μm, 1.82 μm, 1.92 μm or 2.25 μm, etc.

[0097] In some optional modes, the H of the single-crystal ternary cathode material is not less than 80%, and exemplarily can be 81% to 96%, such as 81%, 87%, 88%, 89%, 90%, 91%, 92% or 96%, etc.

[0098] In some optional modes, the particle size of the single-crystal ternary cathode material is not more than 20 μm, which can also be understood as that in the single-crystal ternary cathode material, the particle size of the largest particle is less than or equal to 20 μm.

[0099] In some optional modes, the general formula of the single-crystal ternary cathode material is Li d Ni a Co b M c M’ 1-a-b-c O2, wherein 0.95≤d<1.1, a>0, b>0, c>0, 0.95≤(a+b+c)≤1. The above a, b, c and d are in terms of moles, and the unit is mol.

[0100] M includes at least one of Al and Mn, that is, M can be only Al, M can also be only Mn, and M can also contain Al and Mn at the same time.

[0101] M’ includes at least one of a doping element and a coating element, that is, M’ can be only a doping element, M’ can also be only a coating element, and M’ can also contain a doping element and a coating element at the same time. When a+b+c=1, the single-crystal ternary cathode material does not contain a doping element or a coating element.

[0102] Exemplarily, the above doping element and coating element are each independently selected from at least one of Zr, Sr, Mo, Ba, W, B, Ti, Mg, Li, C, F, Si, Ca, Cu, La, P, Ce, Bi, In, Nb and Y. In some optional modes, the doping element and the coating element can be the same, and in other optional modes, the doping element and the coating element can also be different.

[0103] Exemplarily, the doping agent for providing the doping element can include at least one of an oxide, a fluoride, a carbonate, a hydroxide, a nitride, a boride, and a nitrate corresponding to the doping element. Similarly, the coating agent for providing the coating element can also include at least one of an oxide, a fluoride, a carbonate, a hydroxide, a nitride, a boride, and a nitrate corresponding to the coating element.

[0104] In some optional modes, in the single-crystal ternary cathode material, the cell parameter c and the cell parameter a satisfy c / a≥4.899, such as 4.9174, 4.9234, 4.9375, 4.9425, or 4.9487, etc. The single-crystal ternary cathode material with the above c / a value has good crystallinity and highly ordered layered structure, and the crystal structure is relatively stable. Within the above range, the larger the c / a value, the more excellent the layered structure of the material, and the more conducive to the deintercalation of lithium ions between the layers.

[0105] In some optional modes, the single-crystal ternary cathode material has a (003) crystal face diffraction peak intensity I (003) and a (104) crystal face diffraction peak intensity I (104) satisfying: R=I (003) / I (104) ≥1.51, such as 1.51, 1.62, 1.68, 1.74, or 1.87, etc. The R value can judge the degree of Li and Ni disordering, and the larger the R value, the lower the degree of disordering of the material, and the more conducive to the insertion and extraction of lithium ions.

[0106] In some optional modes, the surface roughness Ra of the electrode sheet corresponding to the single-crystal ternary cathode material is not more than 2.20 μm, exemplarily can be 0.86 μm-2.12 μm, such as 0.86 μm, 1.17 μm, 1.20 μm, 1.23 μm, 1.24 μm, 1.52 μm, 1.61 μm, 1.62 μm, 1.67 μm, 1.75 μm, 1.76 μm, 1.84 μm, or 2.12 μm, etc. The apparent factor of the present disclosure is linearly correlated with the surface roughness of the electrode sheet, and the single-crystal ternary cathode material corresponding to the electrode with the above surface roughness has a neat and smooth shape, and basically no sharp corners.

[0107] Correspondingly, the present disclosure also provides a preparation method of the above single-crystal ternary cathode material, which can include the following steps, for example:

[0108] Step (1): mixing a precursor of a single-crystal ternary cathode material with a first lithium source and then performing first calcination to obtain a first mixture;

[0109] Step (2): performing first crushing of the first mixture in water to obtain a second mixture;

[0110] Step (3): mixing the second mixture with a second lithium source, and then performing a second calcination to obtain a third mixture;

[0111] Step (4): performing a second crushing on the third mixture to obtain a fourth mixture.

[0112] In some optional modes, the type of the precursor of the single-crystal ternary cathode material is a hydroxide precursor, which can be a nickel-cobalt-manganese hydroxide or a nickel-cobalt-aluminum hydroxide.

[0113] The ratio of the total molar amount of the transition metal elements in the precursor of the single-crystal ternary cathode material to the molar amount of lithium elements in the first lithium source can be 1:0.4 to 1:0.7, such as 1:0.4, 1:0.45, 1:0.5, 1:0.55, 1:0.6, 1:0.65, or 1:0.7, etc., and can also be other arbitrary values in the range of 1:0.4 to 1:0.7.

[0114] The temperature of the first calcination can be 650°C to 750°C, such as 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, 710°C, 720°C, 730°C, 740°C, or 750°C, etc., and can also be other arbitrary values in the range of 650°C to 750°C.

[0115] If the temperature of the first calcination is too low, the material can not crystallize; if the temperature of the first calcination is too high, it is easy to cause serious lithium-nickel mixing.

[0116] The time of the first calcination can be 1h to 3h, such as 1h, 1.5h, 2h, 2.5h, or 3h, etc., and can also be other arbitrary values in the range of 1h to 3h.

[0117] The first calcination can be performed in an oxygen-containing atmosphere, for example, the oxygen content in the oxygen-containing atmosphere can be ≥20wt%, such as the oxygen content in the oxygen-containing atmosphere can be 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, 90wt%, or 100wt% etc. In some optional modes, the oxygen content in the oxygen-containing atmosphere is ≥80wt%.

[0118] In the preparation process of the single-crystal ternary cathode material, the first crushing is achieved by thermal expansion and cold contraction effect. Exemplarily, the first mixture obtained by the first calcination is rapidly transferred into water in a high-temperature state. As a reference, the transfer time is not more than 30 min. Based on the high temperature of the first mixture after the first calcination and the water temperature of 0-100 °C, the first mixture will produce thermal expansion and cold contraction effect when it is transferred into water within the above-mentioned transfer time, and the stirring can effectively achieve the crushing. By using this method for the first crushing, the crushing conditions are relatively mild, which can improve the smoothness of the crushed material and reduce or avoid the generation of sharp edges and corners. In addition, by using this method for the first crushing, it is also beneficial to remove the lithium hydroxide remaining on the surface of the first mixture after the first calcination. Moreover, by the first crushing, the material crushing is more sufficient, which is beneficial to improve the element dispersion, reduce the second calcination time, and thus is beneficial to reduce the lithium-nickel mixing.

[0119] In some optional modes, the temperature of the water used for the first crushing is greater than 0 °C and not more than 50 °C, such as 5 °C, 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C or 50 °C, etc., and can also be other arbitrary values in the range of greater than 0 °C and not more than 50 °C.

[0120] The first crushing is carried out under stirring conditions. Exemplarily, the stirring speed can be 100-200 rpm, such as 100 rpm, 120 rpm, 140 rpm, 160 rpm, 180 rpm or 200 rpm, etc., and can also be other arbitrary values in the range of 100-200 rpm. The stirring time can be 5-20 min, such as 5 min, 10 min, 15 min or 20 min, etc., and can also be other arbitrary values in the range of 5-20 min.

[0121] In some optional modes, the second crushing can be carried out by using the airflow crushing method, and in other embodiments, the second crushing can also be carried out by using other methods.

[0122] In some optional modes, the ratio of the total mole amount of lithium elements in the first lithium source and the second lithium source to the total mole amount of transition metal elements in the second mixture can be 1.05:1 to 1.1:1, such as 1.05:1, 1.06:1, 1.07:1, 1.08:1, 1.09:1 or 1.1:1, etc., and can also be other arbitrary values in the range of 1.05:1 to 1.1:1.

[0123] In the preparation of the single-crystal ternary cathode material, the lithium source needs to be excessive. The present disclosure realizes the addition of the lithium source by adopting the mode of adding lithium twice, and the ratio of the total molar amount of lithium elements in the first lithium source and the second lithium source to the total molar amount of transition metal elements in the second mixture can be 1.05:1 to 1.1:1, which can avoid too much lithium source from causing too much residual lithium hydroxide. The residual lithium hydroxide needs to be washed away by using an additional washing reagent on the one hand, and on the other hand, it is an alkaline substance, which will adversely affect the performance of the material. Among them, the amount of the first lithium source used in the first time is less, and through the first calcination, the grain boundaries can be fused, so that the particles are fused together. If the amount of the first lithium source is too much, it is easy to cause the lithium in part of the lattice to be precipitated during the first crushing process, and it is difficult for the second lithium source to be supplemented into the vacancies left after the lithium is precipitated during the second lithium supplementing. In addition, by adopting the mode of adding lithium twice, the reaction between the materials can be more sufficient. The first lithium source is reacted with the precursor first, and then crushed for the first time, which is beneficial to improve the contact area between the second mixture and the second lithium source, and also beneficial to make the lithium more uniformly distributed in the third mixture.

[0124] The temperature of the second calcination can be 800°C to 950°C, such as 800°C, 820°C, 850°C, 880°C, 900°C, 920°C or 950°C, etc., and can also be any other value within the range of 800°C to 950°C.

[0125] The time of the second calcination can be 4h to 6h, such as 4h, 4.5h, 5h, 5.5h or 6h, etc., and can also be any other value within the range of 4h to 6h.

[0126] The second calcination can also be carried out in an oxygen-containing atmosphere. Illustratively, the oxygen content in the oxygen-containing atmosphere can be ≥20wt%, such as 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, 90wt% or 100wt% etc. In some optional modes, the oxygen content in the oxygen-containing atmosphere is ≥80wt%.

[0127] In the process of preparing the single-crystal ternary cathode material, when the single-crystal ternary cathode material contains a doping element, in some optional modes, the precursor of the single-crystal ternary cathode material and the first lithium source can be mixed with a doping reagent for providing the doping element before the first calcination. In some other optional modes, the second mixture and the second lithium source can be mixed with a doping reagent for providing the doping element before the second calcination.

[0128] In the process of preparing the single-crystal ternary cathode material, when the single-crystal ternary cathode material contains a coating element, the preparation method further comprises step (5): mixing the fourth mixture with a coating reagent for providing the coating element before the third calcination.

[0129] In some optional modes, the temperature of the third calcination can be 500-700°C, such as 500°C, 550°C, 600°C, 650°C, or 700°C, etc., and can also be any other value in the range of 500-700°C.

[0130] The time of the third calcination can be 4-6h, such as 4h, 4.5h, 5h, 5.5h, or 6h, etc., and can also be any other value in the range of 4-6h.

[0131] The third calcination can also be performed in an oxygen-containing atmosphere. For example, the oxygen content in the oxygen-containing atmosphere can be ≥20wt%, such as 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, 90wt%, or 100wt% etc. In some optional modes, the oxygen content in the oxygen-containing atmosphere is ≥80wt%.

[0132] In addition, the present disclosure also provides a positive electrode tab, wherein the active material in the positive electrode tab comprises the single-crystal ternary positive electrode material of any one of the preceding embodiments.

[0133] In some optional modes, the first discharge specific capacity of the positive electrode tab corresponding to 0.1C is not less than 171.0mAh / g, and can be exemplarily 171.6-203.4mAh / g, such as 171.6mAh / g, 181.7mAh / g, 183.5mAh / g, 187.2mAh / g, 187.5mAh / g, 188.5mAh / g, 190.3mAh / g, 190.9mAh / g, 193.4mAh / g, 193.7mAh / g, 198.8mAh / g, 201.7mAh / g, 202.2mAh / g, or 203.4mAh / g, etc.

[0134] In some optional modes, the capacity retention rate of the positive electrode tab corresponding to 0.1C cycle for 50 cycles is not less than 89.2%, and can be exemplarily 89.2-99.4%, such as 89.2%, 91.7%, 92.2%, 92.5%, 93.8%, 94.3%, 94.6%, 95.2%, 95.4%, 95.9%, 97.4%, 97.7%, 98.0%, or 99.4%, etc.

[0135] In some alternative manners, the first discharge specific capacity corresponding to 1C of the positive electrode plate is not less than 148.3 mAh / g, which may exemplarily be 148.3 mAh / g-173.9 mAh / g, such as 148.3 mAh / g, 158.8 mAh / g, 159.3 mAh / g, 159.8 mAh / g, 165.1 mAh / g, 165.3 mAh / g, 168.9 mAh / g, or 173.9 mAh / g, etc.

[0136] In some alternative manners, the first discharge specific capacity corresponding to 5C of the positive electrode plate is not less than 125.8 mAh / g, which may exemplarily be 125.8 mAh / g-152.2 mAh / g, such as 125.8 mAh / g, 136.9 mAh / g, 139.5 mAh / g, 140.0 mAh / g, 144.5 mAh / g, 145.8 mAh / g, 148.9 mAh / g, or 152.2 mAh / g, etc.

[0137] The present disclosure also provides a battery cell comprising the positive electrode plate described above.

[0138] By way of example, the battery cell described above may, but is not limited to, be used in an electric device such as a vehicle, a ship, or an aircraft, etc.

[0139] The present disclosure also provides a battery comprising the battery cell described above.

[0140] The present disclosure also provides an electric device comprising the battery cell and / or the battery described above. By way of example, the electric device may, but is not limited to, be a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric aircraft toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0141] The features and performances of the present disclosure are further described in detail below in combination with embodiments.

[0142] Embodiment 1

[0143] The present embodiment provides a single-crystal ternary positive electrode material, and the preparation process thereof comprises:

[0144] Step (1): uniformly grind the precursor of the single-crystal ternary positive electrode material and the first lithium source after mixing, and perform first calcination to obtain a first mixture.

[0145] The precursor of the single-crystal ternary positive electrode material is a nickel-cobalt-manganese hydroxide precursor Ni 0.5 Co 0.2 Mn0.3 The first lithium source is lithium hydroxide. The ratio of the total moles of Ni, Co and Mn in the nickel-cobalt-manganese hydroxide precursor to the moles of Li in the first lithium source is 1:0.55. The first calcination is performed at 700°C under an oxygen-rich atmosphere (oxygen content of 98 wt%) for 2h.

[0146] Step (2): The first mixture is transferred to water at a temperature of 30°C for the first crushing, filtered, and dried to obtain a second mixture.

[0147] The first crushing is performed under stirring at 150 rpm for 10 min, and the drying is performed at 100°C for 12h.

[0148] Step (3): The second mixture is mixed with a second lithium source and subjected to a second calcination to obtain a third mixture.

[0149] The second lithium source is lithium hydroxide. The ratio of the total moles of Ni, Co and Mn in the second mixture to the moles of Li in the second lithium source is 1:0.53. That is, the ratio of the total moles of lithium in the first lithium source and the second lithium source to the total moles of transition metal elements in the second mixture is 1.08:1. The second calcination is performed at 900°C under an oxygen-rich atmosphere (oxygen content of 98 wt%) for 5h.

[0150] Step (4): The third mixture is subjected to a second crushing by means of airflow crushing to obtain a fourth mixture (single-crystal ternary positive electrode material).

[0151] Example 2

[0152] The difference between this example and Example 1 is that the ratio of the total moles of Ni, Co and Mn in the nickel-cobalt-manganese hydroxide precursor to the moles of Li in the first lithium source is 1:0.4.

[0153] Example 3

[0154] The difference between this example and Example 1 is that the ratio of the total moles of Ni, Co and Mn in the nickel-cobalt-manganese hydroxide precursor to the moles of Li in the first lithium source is 1:0.7.

[0155] Example 4

[0156] The difference between this example and Example 1 is that, in Step (2), the stirring time is 5 min.

[0157] Example 5

[0158] The difference between this example and Example 1 is that, in Step (2), the stirring time is 20 min.

[0159] Example 6

[0160] The present embodiment provides a single-crystal ternary cathode material, and a preparation process thereof comprises:

[0161] Step (1): uniformly mix a precursor of a single-crystal ternary cathode material with a first lithium source, and then grind to obtain a first mixture.

[0162] The precursor of the single-crystal ternary cathode material is a nickel-cobalt-aluminum hydroxide precursor Ni 0.821 Co 0.154 Al 0.025 (OH)2. The first lithium source is lithium hydroxide. The ratio of the total number of moles of Ni, Co and Al in the nickel-cobalt-aluminum hydroxide precursor to the number of moles of Li in the first lithium source is 1:0.5. The first calcination is performed at 700°C in an oxygen-rich atmosphere (oxygen content is 98wt%) for 1h.

[0163] Step (2): same as step (2) of embodiment 1.

[0164] Step (3): mix the second mixture with a second lithium source, and then perform second calcination to obtain a third mixture.

[0165] The second lithium source is lithium hydroxide. The ratio of the total number of moles of Ni, Co and Al in the second mixture to the number of moles of Li in the second lithium source is 1:0.55. That is, the ratio of the total number of moles of lithium elements in the first lithium source and the second lithium source to the total number of moles of transition metal elements in the second mixture is 1.05:1. The second calcination is performed at 800°C in an oxygen-rich atmosphere (oxygen content is 98wt%) for 6h.

[0166] Step (4): same as step (4) of embodiment 1.

[0167] Embodiment 7

[0168] The present embodiment provides a single-crystal ternary cathode material, and a preparation process thereof comprises:

[0169] Step (1): uniformly mix a precursor of a single-crystal ternary cathode material with a first lithium source, and then grind to obtain a first mixture.

[0170] The precursor of the single-crystal ternary cathode material is a nickel-cobalt-manganese hydroxide precursor Ni 0.8 Co 0.1 Mn 0.1 (OH)2. In the precursor, the molar ratio of Ni, Co and Mn is 8:1:1. The first lithium source is lithium hydroxide. The ratio of the total number of moles of Ni, Co and Mn in the nickel-cobalt-manganese hydroxide precursor to the number of moles of Li in the first lithium source is 1:0.7. The first calcination is performed at 650°C in an oxygen-containing atmosphere (oxygen content is 80wt%) for 3h.

[0171] Step (2): The first mixture is transferred to water at a temperature of 5°C before 550°C for the first crushing, filtration, drying, to obtain a second mixture.

[0172] The first crushing is performed under stirring conditions of 100 rpm for 15 min, and the drying is performed at 100°C for 12 h.

[0173] Step (3): The second mixture, a second lithium source and zirconium oxide are mixed, uniformly ground and then secondly calcined to obtain a third mixture.

[0174] The second lithium source is lithium hydroxide. The ratio of the total moles of Ni, Co and Mn in the second mixture to the moles of Li in the second lithium source is 1:0.4. That is, the ratio of the total moles of lithium elements in the first lithium source and the second lithium source to the total moles of transition metal elements in the second mixture is 1.1:1. The amount of zirconium oxide is 1000 ppm of the mass of the nickel-cobalt-manganese hydroxide precursor. The second calcination is performed at 950°C under an oxygen-rich atmosphere (oxygen content is 98 wt%) for 4 h.

[0175] Step (4): The third mixture is secondly crushed by using a gas flow crushing method to obtain a fourth mixture (single-crystal ternary positive electrode material).

[0176] Example 8

[0177] The present embodiment provides a single-crystal ternary positive electrode material, and a preparation process thereof includes:

[0178] Step (1): A precursor of the single-crystal ternary positive electrode material is mixed with a first lithium source, uniformly ground, and then firstly calcined to obtain a first mixture.

[0179] The precursor of the single-crystal ternary positive electrode material is a nickel-cobalt-manganese hydroxide precursor Ni 0.34 Co 0.33 Mn 0.33 (OH)2, and the molar ratio of Ni, Co and Mn in the precursor is 1:1:1. The first lithium source is lithium hydroxide. The ratio of the total moles of Ni, Co and Mn in the nickel-cobalt-manganese hydroxide precursor to the moles of Li in the first lithium source is 1:0.6. The first calcination is performed at 750°C under an oxygen-containing atmosphere (oxygen content is 20 wt%) for 2 h.

[0180] Step (2): The first mixture is transferred to water at a temperature of 50°C before 650°C for the first crushing, filtration, drying, to obtain a second mixture.

[0181] The first crushing is performed for 15 min under stirring at 200 rpm, and the drying is performed for 12 h at 100°C.

[0182] Step (3): mixing the second mixture with a second lithium source and aluminum oxide, grinding uniformly, and then performing second calcination to obtain a third mixture.

[0183] The second lithium source is lithium hydroxide. The ratio of the total moles of Ni, Co and Mn in the second mixture to the moles of Li in the second lithium source is 1:0.45. That is, the ratio of the total moles of lithium in the first lithium source and the second lithium source to the total moles of transition metal elements in the second mixture is 1.05:1. The amount of aluminum oxide is 1000 ppm of the mass of the nickel-cobalt-manganese hydroxide precursor. The second calcination is performed for 5 h at 900°C under an oxygen-rich atmosphere (oxygen content is 98 wt%).

[0184] Step (4): performing second crushing on the third mixture in the form of airflow crushing to obtain a fourth mixture (single-crystal ternary positive electrode material).

[0185] Example 9

[0186] The difference between this example and Example 1 is that it further includes step (5): mixing the fourth mixture with aluminum oxide, grinding uniformly, and then performing third calcination.

[0187] The amount of aluminum oxide is 1 wt% of the mass of the fourth mixture. The third calcination is performed for 4 h at 500°C under an oxygen-rich atmosphere (oxygen content is 98 wt%).

[0188] Example 10

[0189] The difference between this example and Example 2 is that it further includes step (5): mixing the fourth mixture with aluminum oxide, grinding uniformly, and then performing third calcination.

[0190] The amount of aluminum oxide is 1 wt% of the mass of the fourth mixture. The third calcination is performed for 4 h at 500°C under an oxygen-rich atmosphere (oxygen content is 98 wt%).

[0191] Example 11

[0192] The difference between this example and Example 4 is that it further includes step (5): mixing the fourth mixture with aluminum oxide, grinding uniformly, and then performing third calcination.

[0193] The amount of aluminum oxide is 1 wt% of the mass of the fourth mixture. The third calcination is performed for 4 h at 700°C under an oxygen-rich atmosphere (oxygen content is 98 wt%).

[0194] Example 12

[0195] The difference between this example and Example 5 is that it further comprises step (5): mixing the fourth mixture with aluminum oxide, grinding uniformly and then performing the third calcination.

[0196] The amount of aluminum oxide is 1 wt% of the mass of the fourth mixture. The third calcination is performed at 700°C under an oxygen-rich atmosphere (oxygen content is 98 wt%) for 4h.

[0197] Example 13

[0198] The difference between this example and Example 6 is that it further comprises step (5): mixing the fourth mixture with H3BO3, grinding uniformly and then performing the third calcination.

[0199] The amount of H3BO3 is 1 wt% of the mass of the fourth mixture. The third calcination is performed at 600°C under an oxygen-rich atmosphere (oxygen content is 98 wt%) for 6h.

[0200] Example 14

[0201] The difference between this example and Example 7 is that it further comprises step (5): mixing the fourth mixture with aluminum oxide, grinding uniformly and then performing the third calcination.

[0202] The amount of aluminum oxide is 1 wt% of the mass of the fourth mixture. The third calcination is performed at 700°C under an oxygen-rich atmosphere (oxygen content is 98 wt%) for 4h.

[0203] Comparative Example 1

[0204] The difference between this comparative example and Example 1 is that the nickel-cobalt-manganese hydroxide precursor and the lithium source (lithium hydroxide) are mixed once and then ground uniformly, and then calcined, and then the calcined product is subjected to airflow crushing.

[0205] The nickel-cobalt-manganese hydroxide precursor is the same as that used in Example 1. The ratio of the total moles of Ni, Co and Mn in the nickel-cobalt-manganese hydroxide precursor to the moles of Li in the lithium source is 1:1.08. The calcination is performed at 900°C under an oxygen-rich atmosphere (oxygen content is 98 wt%) for 12h.

[0206] Comparative Example 2

[0207] The difference between this comparative example and Example 1 is that it does not comprise step (2).

[0208] That is, the first mixture obtained in step (1) of Example 1 is directly mixed with the second lithium source and then subjected to the second calcination, and then step (4) of Example 1 is performed.

[0209] Comparative Example 3

[0210] The difference between the present comparative example and Comparative Example 1 is that the material obtained after the gas stream is broken is mixed with aluminum oxide, and after being ground uniformly, calcination is carried out under an oxygen-rich atmosphere (oxygen content is 98wt%) at 500°C for 4h.

[0211] The amount of aluminum oxide is 1wt% of the mass of the material obtained after the gas stream is broken.

[0212] Comparative Example 4

[0213] The difference between the present comparative example and Comparative Example 2 is that the material obtained after the gas stream is broken is mixed with aluminum oxide, and after being ground uniformly, calcination is carried out under an oxygen-rich atmosphere (oxygen content is 98wt%) at 500°C for 4h.

[0214] The amount of aluminum oxide is 1wt% of the mass of the material obtained after the gas stream is broken.

[0215] Comparative Example 5

[0216] The difference between the present comparative example and Example 1 is that the first breaking is carried out by dry grinding after the first mixture is cooled to room temperature.

[0217] Test Example

[0218] (1) Taking the single-crystal ternary positive electrode material obtained in Examples 1-5 and Comparative Example 1 as an example, the single-crystal ternary positive electrode material obtained is characterized by X-ray diffraction, and the obtained XRD pattern is shown in Figure 1.

[0219] As can be seen from Figure 1, the diffraction peaks of the XRD spectra of all single-crystal materials completely correspond to the LiNiO2 standard card (PDF #74-0919), indicating that all the synthesized materials are hexagonal α-NaFeO2 layer structure (R-3m space group), and there is no other impurity phase. In addition, it can be seen from Figure 1 that two groups of peaks (006) / (102) and (108) / (110) are obviously split, indicating that all the synthesized materials have good crystallinity and highly ordered layered structure.

[0220] Further, the XRD pattern is fitted by MDI.Jade.6.0, and the lattice parameters are calculated respectively, and the results are shown in Table 1.

[0221] Table 1 Lattice parameter results

[0222] As can be seen from Table 1, the c / a of the single-crystal material prepared in the examples is all greater than 4.899, indicating that all the materials have good layered structure; in addition, the R value corresponding to Examples 1-5 is higher than that of Comparative Example 1, indicating that the lithium-nickel mixing degree of the material obtained in Examples 1-5 is lower than that of the material obtained in Comparative Example 1.

[0223] (2), taking the single-crystal ternary positive electrode material obtained in Example 1, Example 10 and Comparative Example 1 as examples, scanning electron microscopy observation was performed on each single-crystal ternary positive electrode material, and the obtained SEM images are shown in Figure 2. In Figure 2, (A) represents the SEM image of the single-crystal ternary positive electrode material obtained in Example 1, (B) represents the SEM image of the single-crystal ternary positive electrode material obtained in Example 10, and (C) represents the SEM image of the single-crystal ternary positive electrode material obtained in Comparative Example 1.

[0224] As can be seen from Figure 2, compared with the single-crystal ternary positive electrode material obtained in Comparative Example 1, the single-crystal ternary positive electrode materials obtained in Example 1 and Example 10 have better circularity and smoother corners. The circularity of the single-crystal ternary positive electrode material obtained in Example 10 is better than that of Example 1.

[0225] (3), performance detection.

[0226] ①, the apparent physical quantity test was performed on the single-crystal ternary positive electrode materials prepared in Examples 1-8, Comparative Examples 1-2 and Comparative Example 5 without coating, and each single-crystal ternary positive electrode material was prepared into an electrode, and the surface roughness of each electrode was tested, and the results are shown in Table 2.

[0227] The test method includes:

[0228] A, the microstructure of the sample was observed by JEOL JSM-6490LV scanning electron microscope to obtain a scanning electron microscope image. The sample preparation is as follows: the conductive glue for scanning electron microscope test is pasted on the sample table, the sample powder is picked up with a toothpick, the arm is shaken gently, the powder is gently scattered on the conductive glue, then the ear ball is used to blow off the powder that is not firmly bonded, and the above operation is repeated until a layer of powder is evenly spread on the surface of the conductive glue.

[0229] Subsequently, ImageJ was used to analyze the shape of the single particle in the scanning electron microscope image, and parameters such as the number of particles, area, perimeter and circularity were collected. The number of measurement samples for each single-crystal material sample was 50, and random sampling was performed.

[0230] B, the particle size and particle size distribution of the single-crystal ternary positive electrode material were analyzed by LS13320 laser particle size analyzer. Specifically, wet dispersion technology was used, mechanical stirring was used to make the sample evenly dispersed, ultrasonic high-frequency oscillation was used to make the agglomerated particles fully dispersed, and electromagnetic circulating pump was used to make the particles of different sizes evenly distributed in the whole circulating system.

[0231] C, the surface roughness Ra of the electrode was measured by SJ-210 surface roughness meter. Different positions of each electrode sample were measured for 3 times, and the average value was finally taken.

[0232] The preparation method of the electrode is as follows: single-crystal ternary positive electrode material, conductive carbon black and PVDF are weighed according to the mass ratio of 8:1:1, ground and put into a bottle, an appropriate amount of NMP solvent is added, and stirring is carried out on a stirrer for 24h to form a uniform slurry. The prepared slurry is uniformly coated on a clean aluminum foil by a wet film preparation device, and the loading amount is controlled to be 2.5±0.05mg / cm 2 Then it is placed in a 100℃ vacuum drying oven for 24h to dry until there is no material adhesion.

[0233] Table 2 test results

[0234] It can be seen from Table 2 that adjusting the preparation process conditions can obtain single-crystal materials with different apparent factors.

[0235] ②, the single-crystal ternary positive electrode material prepared in Examples 1-8, Comparative Examples 1-2 and Comparative Example 5 is not coated and is subjected to electrochemical performance testing.

[0236] The test method includes: the electrode corresponding to C in the above ① is further punched into a circular electrode sheet with a diameter of 12mm, then a metal lithium round sheet is used as a negative electrode, Celgard 2300 is used as a separator, 1mol / L LiPF6 solution (a mixed solution of EMC, DC and DMC in a volume ratio of 1:1:1) is used as an electrolyte, a CR2032 type button cell is assembled, and a LANHE CT2001A battery test system is used for rate performance test, and the results are shown in Table 3.

[0237] Table 3 test results

[0238] It can be seen from Table 3 that the single-crystal ternary positive electrode material prepared in Examples 1-8 has a higher specific capacity, cycle stability and rate performance.

[0239] ③, the coated single-crystal ternary positive electrode material prepared in Examples 9-13 and Comparative Examples 3-4 is subjected to apparent physical quantity testing and surface roughness testing of the prepared electrode, and the test method is the same as the above ①, and the test results are shown in Table 4.

[0240] Table 4 test results

[0241] It can be seen from Table 4 that the coated single-crystal ternary positive electrode material has little difference in hardness and particle size distribution coefficient (D 90 / D 10 ) compared with the uncoated related material, but the sphericity is improved, so that the apparent factor is reduced, and the apparent factor of the coated single-crystal ternary positive electrode material and the surface roughness of the electrode also meet a positive correlation.

[0242] ④ The coated single-crystal ternary cathode materials prepared in Examples 9-13 and Comparative Examples 3-4 were respectively prepared into electrodes and their electrochemical performance was tested. The test method was the same as in ② above, and the test results are shown in Table 5.

[0243] Table 5 Test Results

[0244] As can be seen from Table 5, the batteries corresponding to the electrodes prepared by the single-crystal ternary cathode materials provided in Examples 9 to 13 of this disclosure have high specific capacity and cycle stability.

[0245] ⑤ The electrode sheets corresponding to the embodiments in ① and ④, as well as the comparative examples, were placed on a hydraulic press and rolled at pressures of 2 MPa, 6 MPa, and 15 MPa, respectively. The relationship between the apparent factor of each single-crystal ternary cathode material and the surface roughness of the electrode sheets after different pressures was statistically analyzed. The results are shown in Figure 3. In Figure 3, the 17 points corresponding to each diagonal line represent the results of 13 embodiments (Examples 1-13) and 4 comparative examples (Comparative Examples 1-4). As can be seen from Figure 3, whether before or after coating, the apparent factor of the single-crystal ternary cathode material and the surface roughness of the electrode sheet are linearly positively correlated under different rolling pressures.

[0246] In summary, this disclosure proposes a single-crystal ternary cathode material with a specific range of apparent factors. This material exhibits smooth surfaces and rounded edges, which is beneficial for electrodes and batteries using it as the cathode material to achieve higher specific capacity, rate performance, and cycle performance. The corresponding preparation method for the single-crystal ternary cathode material is simple, easy to operate, and suitable for industrial-scale production. Industrial applicability

[0247] The single-crystal ternary cathode material disclosed herein has a smooth surface and rounded edges, enabling it to exhibit high specific capacity, rate performance, and cycle performance when used as a cathode material. Its preparation method is simple, easy to operate, and suitable for industrial-scale production. This single-crystal ternary cathode material can be further used to prepare batteries and electrical devices with excellent electrochemical performance.

Claims

1. A single-crystalline ternary cathode material, characterized in that, The apparent factor of the single-crystal ternary positive electrode material The apparent factor of the single-crystal ternary positive electrode material is 1.1-3.0; wherein x = D 90 / D 10 , 2≤x≤5; D 90 is the particle size corresponding to the cumulative particle size distribution of 90% by volume of the single-crystal ternary cathode material, D 10 is the particle size corresponding to the cumulative particle size distribution of 10% by volume of the single-crystal ternary cathode material; the D 10 of the single-crystal ternary cathode material is not more than 2.4 μm; S(D 90 ) is the number average circularity, which is equal to the sum of the circularities of all target particles contained in the single-crystal ternary positive electrode material divided by n; the circularity Q = l2 / l1, defining the area and the circumference corresponding to the two-dimensional projection map of a single-particle target particle as S1 and l1, respectively, defining the circumference of a circle with area S1 as l2, and defining the target particle as a single-crystal ternary positive electrode material particle with a particle size greater than or equal to D 90 in the single-crystal ternary positive electrode material; n is the total number of the target particles contained in the single-crystal ternary positive electrode material; H is hardness, wherein D 10 ’ is the particle size corresponding to 10% of the cumulative particle size distribution by volume of the compacted material obtained after compacting the single-crystal ternary cathode material using a pressure of 200 MPa; D 10 ’ is not more than 2.3 μm.

2. The single-crystalline ternary cathode material of claim 1, wherein, The single-crystal ternary positive electrode material comprises at least one of the following characteristics: Feature one: the D50 of the single-crystal ternary cathode material is not more than 8.6 μm 90 not more than 8.6 μm; Characteristic two: the H of the single-crystal ternary positive electrode material is not less than 80%; Feature 3: The S(D) of the single-crystal ternary cathode material 90 (Not exceeding 0.9) 3. The single-crystalline ternary cathode material of claim 2, wherein, The apparent factor of the single-crystal ternary positive electrode material is 1.1634-2.9571; And / or, the x of the single-crystal ternary positive electrode material is 2.36-3.88; and / or, the D50 of the single-crystal ternary cathode material is 5.01 pm to 8.56 pm. 90 5.01 pm to 8.56 pm. And / or, the D50 of the single-crystal ternary positive electrode material is 1.81 pm to 2.34 pm. 10 1.81 pm to 2.34 pm. And / or, the H of the single-crystal ternary positive electrode material is 81%-96%; and / or, the single-crystal ternary cathode material has S(D 90 ) of 0.68-0.87; and / or, the D50 of the single-crystal ternary cathode material is 1.57 pm to 2.25 pm. 10 ’ is 1.57 pm to 2.25 pm.

4. The single-crystalline ternary cathode material of any one of claims 1-3, wherein, The single-crystal ternary positive electrode material further comprises at least one of the following characteristics: Characteristic four: the particle size of the single-crystal ternary positive electrode material is not more than 20 μm; Feature five: the single-crystal ternary positive electrode material has a general formula of Li d Ni a Co b M c M’ 1-a-b-c O2, wherein 0.95≤d<1.1, a>0, b>0, c>0, 0.95≤(a+b+c)≤1; M includes at least one of Al and Mn, M’ includes at least one of a doping element and a coating element, the doping element and the coating element are independently selected from at least one of Zr, Sr, Mo, Ba, W, B, Ti, Mg, Li, C, F, Si, Ca, Cu, La, P, Ce, Bi, In, Nb and Y; Characteristic six: in the single-crystal ternary positive electrode material, the cell parameter c and the cell parameter a satisfy c / a≥4.899; Feature seven: the (003) crystal face diffraction peak intensity I of the single-crystal ternary cathode material (003) with the (104) crystal face diffraction peak intensity I (104) satisfies: I (003) / I (104) ≥1.51; Characteristic eight: the surface roughness Ra of the electrode sheet corresponding to the single-crystal ternary positive electrode material is not more than 2.20 μm.

5. The single-crystalline ternary cathode material of claim 4, wherein, The doping reagent for providing the doping element comprises at least one of the oxides, fluorides, carbonates, hydroxides, nitrides, borides and nitrates corresponding to the doping element; And / or, the coating reagent for providing the coating element comprises at least one of the oxides, fluorides, carbonates, hydroxides, nitrides, borides and nitrates corresponding to the coating element.

6. The single-crystalline ternary cathode material of claim 4 or 5, wherein, The surface roughness Ra of the electrode sheet corresponding to the single-crystal ternary positive electrode material is 0.86 μm-2.12 μm.

7. A method for producing a single-crystal ternary cathode material according to any one of claims 1 to 6, characterized by, The method comprises the following steps: Mixing the precursor of the single-crystal ternary positive electrode material with a first lithium source and then performing first calcination to obtain a first mixture; Rapidly transferring the first mixture to water under a high-temperature state and combining stirring to achieve first crushing to obtain a second mixture; Mixing the second mixture with a second lithium source and then performing second calcination to obtain a third mixture; Performing second crushing on the third mixture to obtain a fourth mixture.

8. The preparation method according to claim 7, characterized in that, The preparation of the first mixture comprises at least one of the following characteristics: Characteristic 1: the type of the precursor of the single-crystal ternary positive electrode material is a hydroxide precursor; Characteristic 2: the ratio of the total molar amount of transition metal elements in the precursor of the single-crystal ternary positive electrode material to the molar amount of lithium elements in the first lithium source is 1:0.4 to 1:0.7; Characteristic 3: the temperature of the first calcination is 650°C-750°C; Characteristic 4: the time of the first calcination is 1 h-3 h; Characteristic 5: the first calcination is performed under an oxygen-containing atmosphere.

9. The production method according to claim 8, characterized by, The precursor of the single-crystal ternary positive electrode material comprises a nickel-cobalt-manganese hydroxide or a nickel-cobalt-aluminum hydroxide.

10. The method of any one of claims 7 to 9, wherein the method further comprises, The first crushing comprises at least one of the following characteristics: Characteristic 6: the first crushing is achieved through thermal expansion and cold contraction effect; Characteristic 7: the temperature of the water used for the first crushing is greater than 0°C and not more than 50°C; Characteristic 8: the stirring speed of the first crushing is 100 rpm-200 rpm; Characteristic 9: the stirring time of the first crushing is 5 min-20 min; And / or, the second crushing is performed in an airflow crushing mode.

11. The method of any one of claims 8 to 10, wherein the method further comprises, The transferring time of the first mixture to water under a high-temperature state is not more than 30 min.

12. The method of any one of claims 7 to 11, wherein, The preparation of the third mixture comprises at least one of the following characteristics: Feature 10: the ratio of the total mole amount of lithium element in the first lithium source and the second lithium source to the total mole amount of transition metal element in the second mixture is 1.05:1 to 1.1:1; Feature 11: the temperature of the second calcination is 800℃ to 950℃; Feature 12: the time of the second calcination is 4h to 6h; Feature 13: the second calcination is performed in an oxygen-containing atmosphere.

13. The process according to any one of claims 7 to 12, characterized in that, When the single-crystal ternary cathode material contains a doping element, the precursor of the single-crystal ternary cathode material, the first lithium source, and a doping reagent for providing the doping element are mixed and then subjected to the first calcination; or, the second mixture, the second lithium source, and a doping reagent for providing the doping element are mixed and then subjected to the second calcination. Or, when the single-crystal ternary cathode material contains a coating element, the preparation method further comprises: mixing the fourth mixture and a coating reagent for providing a coating element and then performing a third calcination.

14. The method of claim 13, wherein, The oxygen content in the oxygen-containing atmosphere of the first calcination is ≥20wt%; and / or, the second calcination is performed in an oxygen-containing atmosphere with an oxygen content of ≥20wt%; and / or, the third calcination is performed in an oxygen-containing atmosphere with an oxygen content of ≥20wt%.

15. A positive electrode sheet characterized by comprising: The active material in the positive electrode sheet comprises the single-crystal ternary cathode material according to any one of claims 1 to 6.

16. The cathode sheet of claim 15, wherein, The positive electrode sheet has at least one of the following features: Feature Nine: the first discharge specific capacity of the positive electrode sheet corresponding to 0.1C is not less than 171.0mAh / g; Feature Ten: the capacity retention rate of the positive electrode sheet corresponding to 0.1C after 50 cycles is not less than 89.2%; Feature Eleven: the first discharge specific capacity of the positive electrode sheet corresponding to 1C is not less than 148.3mAh / g; Feature Twelve: the first discharge specific capacity of the positive electrode sheet corresponding to 5C is not less than 125.8mAh / g.

17. A battery cell, characterized by The battery monomer contains the positive electrode sheet according to claim 15 or 16.

18. A battery, characterized by The battery contains the battery monomer according to claim 17.

19. An electrical device, comprising: The electric device comprises the battery monomer according to claim 17 or the battery according to claim 18.

20. The powered device of claim 19, wherein, The electric device comprises a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, or a spacecraft. The electric device comprises a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, or a spacecraft.

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