Single-crystal positive electrode material, preparation method thereof, positive electrode sheet, lithium ion battery and electric device

Abstract

The application belongs to the technical field of batteries, and particularly relates to a single-crystal positive electrode material, a preparation method thereof, a positive electrode sheet, a lithium ion battery and an electric device, the single-crystal positive electrode material comprising Li 1+ a Ni x Co y Mn z A m O2, and a single-particle roundness PD of the single-crystal positive electrode material is 0.0-0.8. The single-crystal positive electrode material has good surface smoothness, is used for preparing a solid-state battery, and solid-solid contact of an electrolyte with the single-crystal positive electrode material is closer, so that interface defects and voids can be effectively reduced, interface impedance can be significantly reduced, a stable ion transmission channel can be provided, capacity and cycle performance are improved, and lithium dendrite growth can be inhibited, and safety is improved.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to single-crystal cathode materials and their preparation methods, cathode sheets, lithium-ion batteries, and electrical devices. Background Technology

[0002] Solid-state batteries, due to their absence of liquid electrolytes, offer enhanced safety and high energy density, making them a significant development direction in the new energy field in recent years. Ternary cathode materials in solid-state batteries are mainly divided into polycrystalline and monocrystalline types. Polycrystalline materials are composed of aggregated nanoparticles, which are prone to cracking at grain boundaries during battery cycling due to anisotropic volume changes. This hinders ion / electron transport and causes problems with solid-solid contact, resulting in faster performance degradation. In contrast, monocrystalline cathode materials lack grain boundaries and crystallographic uniformity, exhibiting a more stable structure and interface stability, thus demonstrating superior cycle performance. However, monocrystalline cathode materials still suffer from issues such as uneven particle size, wide particle size distribution, poor individual particle roundness, and surface roughness, meaning their performance in solid-state batteries has not yet reached its optimal level. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention proposes a single-crystal cathode material and its preparation method, a cathode sheet, a lithium-ion battery, and an electrical device. This single-crystal cathode material has good surface smoothness and, when used in the preparation of solid-state batteries, can effectively improve the solid-solid interface contact effect, thereby increasing capacity, cycle performance, and safety.

[0004] In a first aspect, this application provides a single-crystal cathode material. According to embodiments of this application, the single-crystal cathode material comprises: Li 1+a Ni x Co y Mn z A m O2, Wherein, 0.1≤a≤0.1, 0.8≤x≤1.0, 0.0≤y≤0.2, 0.0≤z≤0.2, and 0.0<m<0.1; A includes at least one of the following elements: Al, Ti, Zr, Na, Sr, K, Ca, La, Ce, Pr, Nd, Ta, V, Rh, Ru, Ga, In, Y, Cu, Mg, Zn, Mo, Nb, Sb, P, Sn, W, Cl, F, and B. The single-particle roundness PD of the single-crystal cathode material is 0.0~0.8.

[0005] The single-crystal cathode material of this application controls the PD to be 0.0~0.8. The single-crystal cathode material has rounded edges, high surface smoothness, and low edge sharpness. When used in solid-state batteries, the electrolyte can be better coated on the surface of the single particle, which can effectively improve the solid-solid interface contact between the single-crystal cathode material and the electrolyte, thereby improving the ion transport efficiency and the electrical and safety performance of the solid-state battery.

[0006] According to embodiments of this application, the single-crystal cathode material satisfies at least one of the following conditions: The single-particle roundness PD of the single-crystal cathode material is 0.02~0.4; A includes at least one of the elements Al, Ti, Zr, Sr, La, Ce, Pr, Ta, W, Y, Mg, Zn, Mo, Nb, Sb, Sn, P, Cl, F, and B.

[0007] According to embodiments of this application, the uniformity of edge roundness U between different particles of the single-crystal cathode material PD The value is 0.0~0.6, preferably 0.01~0.3.

[0008] According to embodiments of this application, the single-crystal cathode material satisfies at least one of the following conditions: The single-particle roundness S of the single-crystal cathode material CP The value is 0.0~0.4, preferably 0.05~0.25; The uniformity of roundness among different particles of the single-crystal cathode material U CP The value is 0.0~0.3, preferably 0.05~0.15.

[0009] According to embodiments of this application, the single-crystal cathode material satisfies at least one of the following conditions: The proportion of granules after compression in the single-crystal cathode material is 0%~20%, preferably 0%~15%; K before and after pressurization of the single-crystal cathode material 90 Volatility V K90 The value is 0~0.15, preferably 0~0.1.

[0010] According to embodiments of this application, the single-crystal cathode material satisfies at least one of the following conditions: I (003) / I (104) The value is 1.2~3.5, preferably 1.4~2.8; I (003) / (I (003) +I (101) +I (104) The value is 0.25~0.85, preferably 0.35~0.75; Among them, I (003)I (101) I (104) These are the absolute intensity values ​​of the (003) peak, (101) peak, and (104) peak in the XRD diffraction pattern of the single-crystal cathode material, respectively.

[0011] According to embodiments of this application, the Li / Ni mixture of the single-crystal cathode material is 0%~2.0%, preferably 0%~1.5%.

[0012] A second aspect of this application provides a method for preparing the aforementioned single-crystal cathode material. According to an embodiment of this application, the method includes: pre-sintering a first mixture containing a nickel-cobalt-manganese precursor, a first lithium salt, and a first additive under rotating conditions to obtain a first processed product; mixing the first processed product with an optional second lithium salt and performing a first sintering to obtain a second processed product; mixing the second processed product with a second additive and performing a second sintering to obtain a third processed product; mixing the third processed product with a third additive and performing a third sintering to obtain the single-crystal cathode material; wherein the first lithium salt is lithium hydroxide; based on the total mass of the first lithium salt and the second lithium salt, the mass percentage of the first lithium salt is 50% to 100%.

[0013] In the method described in this application, pre-sintering is performed while maintaining the rotation of the first mixture, which effectively improves the contact between the first lithium salt and the nickel-cobalt-manganese precursor. High-temperature sintering is then performed, resulting in a single-crystal cathode material product with high roundness and a smooth surface. The prepared cathode material exhibits microscopic characteristics such as low cation mixing and better layered structure, and macroscopically displays narrow particle size distribution, good sphericity, good surface smoothness, high roundness, and high compressive strength. When used in solid-state batteries, the electrolyte can better coat the surface of the cathode material particles, which is beneficial for ion transport and improves the battery's electrical and safety performance.

[0014] According to an embodiment of this application, based on the total mass of the first lithium salt and the second lithium salt, the mass percentage of the first lithium salt is 60% to 80%.

[0015] According to embodiments of this application, the above method satisfies at least one of the following conditions: The heating rate of the pre-sintering is 2℃ / min to 10℃ / min; The pre-sintering temperature is 500℃~850℃; The pre-sintering holding time is 4h~14h; The pre-sintering atmosphere is at least one of air, oxygen, and nitrogen; The pre-sintering is carried out in a rotary kiln; The rotation speed is 100 rpm to 2400 rpm.

[0016] According to an embodiment of this application, the first sintering includes a first-stage sintering and a second-stage sintering performed sequentially, and satisfies at least one of the following conditions: The heating rate of the first sintering section is 3℃ / min~10℃ / min; The sintering temperature of the first section is 400℃~700℃; The holding time for the first sintering stage is 1 hour to 7 hours; The heating rate for the two-stage sintering is 2℃ / min to 8℃ / min; The temperature for the two-stage sintering is 700℃~950℃; The holding time for the two-stage sintering is 5h~15h; The atmosphere for the first sintering is at least one of air, oxygen, and nitrogen.

[0017] According to embodiments of this application, the above method satisfies at least one of the following conditions: The heating rate for the second sintering is 2℃ / min to 8℃ / min; The second sintering temperature is 630℃~760℃; The second sintering holding time is 4h~10h; The atmosphere for the second sintering is at least one of air, oxygen, and nitrogen.

[0018] According to embodiments of this application, the above method satisfies at least one of the following conditions: The heating rate of the third sintering is 2℃ / min to 8℃ / min; The temperature of the third sintering is 300℃~550℃; The holding time for the third sintering is 4h~10h; The atmosphere for the third sintering is at least one of air, oxygen, and nitrogen.

[0019] According to embodiments of this application, the above method satisfies at least one of the following conditions: The nickel-cobalt-manganese precursor is Ni x Co y Mn z (OH)2, Ni x Co y Mn z O p At least one of the following, wherein 0.8≤x≤1.0, 0.0≤y≤0.2, 0.0≤z≤0.2, and 0.7≤p≤1.6; The second lithium salt includes at least one of LiOH and Li2CO3; The first additive includes H2WO4, WO3, NaOH, Al(OH)3, Al2O3, ZrO2, Nb2O5, LiNbO3, CeO2, Sr(OH)2, Sr(NO3)2, SrCO3, SrTiO3, La2O3, La(OH)3, Pr2O3, and Pr6O. 11 At least one of the following: Nd₂O₃, Ta₂O₅, V₂O₅, Rh₂O₃, RuO₄, RuO₂, GaAlP, GaN, Ga₂O₃, In₂O₃, Y₂O₃, MgO, MgCl₂, MgF₂, Mg(OH)₂, MgCO₃, ZnO, MoO₃, Sb₂O₅, SnO₂, TiB₂, H₃BO₃, H₂ZrF₆, YF₃, LiF; The second additive includes H2WO4, WO3, NaOH, Al(OH)3, Al2O3, ZrO2, Nb2O5, LiNbO3, CeO2, Sr(OH)2, Sr(NO3)2, SrCO3, SrTiO3, La2O3, La(OH)3, Pr2O3, and Pr6O. 11 At least one of the following: Nd₂O₃, Ta₂O₅, V₂O₅, Rh₂O₃, RuO₄, RuO₂, GaAlP, GaN, Ga₂O₃, In₂O₃, Y₂O₃, MgO, MgCl₂, MgF₂, Mg(OH)₂, MgCO₃, ZnO, MoO₃, Sb₂O₅, SnO₂, TiB₂, H₃BO₃, H₂ZrF₆, YF₃, CoO, Co₂O₃, Co₃O₄, Co(OH)₂, Co(OH)₃, CoOOH, CoF₃; The third additive includes H2WO4, WO3, NaOH, Al(OH)3, Al2O3, Nb2O5, LiNbO3, CeO2, Sr(OH)2, Sr(NO3)2, SrCO3, SrTiO3, La2O3, La(OH)3, Pr2O3, and Pr6O. 11 At least one of the following: Nd2O3, Ta2O5, V2O5, Rh2O3, RuO4, RuO2, GaAlP, GaN, Ga2O3, In2O3, Y2O3, MgO, MgCl2, MgF2, Mg(OH)2, MgCO3, ZnO, MoO3, Sb2O5, SnO2, TiB2, H3BO3, H2ZrF6, YF3, LiF, lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, lithium aluminum germanium phosphate, and lithium aluminum titanium phosphate.

[0020] In a third aspect, this application provides a positive electrode sheet. According to an embodiment of this application, the positive electrode sheet comprises the single-crystal positive electrode material described above. This positive electrode sheet possesses all the features and advantages of the single-crystal positive electrode material described above, which will not be repeated here.

[0021] In a fourth aspect, this application provides a lithium-ion battery. According to an embodiment of this application, the lithium-ion battery includes the aforementioned single-crystal cathode material or the aforementioned cathode sheet. This lithium-ion battery possesses all the features and advantages of the aforementioned single-crystal cathode material and the aforementioned cathode sheet, which will not be elaborated upon here.

[0022] According to an embodiment of this application, the lithium-ion battery is an all-solid-state battery.

[0023] A fifth aspect of this application provides an electrical device. According to an embodiment of this application, the electrical device includes the aforementioned single-crystal cathode material, the aforementioned cathode sheet, or the aforementioned lithium-ion battery. This electrical device possesses all the features and advantages of the aforementioned single-crystal cathode material, the aforementioned cathode sheet, or the aforementioned lithium-ion battery, which will not be elaborated upon here. Attached Figure Description

[0024] Figure 1 This is a SEM image of the single-crystal cathode material prepared in Example 1 of this application.

[0025] Figure 2 This is a SEM image of the single-crystal cathode material prepared in Comparative Example 4 of this application.

[0026] Figure 3 This is a SEM image of the single-crystal cathode material prepared in Comparative Example 5 of this application. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0028] In a first aspect, this application provides a single-crystal cathode material. According to embodiments of this application, the single-crystal cathode material comprises: Li 1+a Ni x Co y Mn z A m O2, Wherein, 0.1≤a≤0.1, 0.8≤x≤1.0, 0.0≤y≤0.2, 0.0≤z≤0.2, and 0.0<m<0.1; A includes at least one of the following elements: Al, Ti, Zr, Na, Sr, K, Ca, La, Ce, Pr, Nd, Ta, V, Rh, Ru, Ga, In, Y, Cu, Mg, Zn, Mo, Nb, Sb, P, Sn, W, Cl, F, and B. The single-particle roundness PD of the single-crystal cathode material is 0.0~0.8 (specifically, such as 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or any two of them).

[0029] Specifically, a smaller PD value indicates that the edges of the single-crystal cathode material particles are more rounded, without obvious sharp edges. A larger PD value indicates that the edges of the single-crystal cathode material particles are more angular. If the single-crystal cathode material particles have more sharp edges, it is detrimental to the coating of the solid electrolyte when used in solid-state batteries, resulting in more severe uneven solid-solid contact, hindering ion transport within the particles, and thus affecting the capacity of the single-crystal cathode material. The single-crystal cathode material of this application controls the PD to be 0.0~0.8, with rounded edges, high surface smoothness, and low edge sharpness. This allows the electrolyte to be better coated on the surface of the single particles, effectively improving the solid-solid interface contact between the single-crystal cathode material and the electrolyte, thereby increasing ion transport efficiency and improving the electrical and safety performance of the solid-state battery.

[0030] In this paper, the PD detection method is as follows: Step 1, take SEM images of the single-crystal cathode material under a scanning electron microscope (SEM) at a magnification of 30K, and select individual particles with a particle size of D. 50 ±D 50 Particles within a 20% range are selected as target particles. Step 2: Using the Metis software, 32 line segments passing through the center of each particle are drawn. The angle between adjacent line segments and the particle's center point is controlled within 11.25±5°. The starting and ending points of the line segments are located on the particle's outline, resulting in 64 points on the particle's outline, labeled A1, A2, A3, ..., A... 64 Step 3: Connect any two adjacent points to obtain 64 line segments. Each pair of adjacent line segments forms a sacral angle, resulting in 64 sacral angles. The software Metis is used to process these 64 sacral angles and obtain their angle values, which are labeled G1, G2, G3, ..., G... 64 Step 4, according to formula G p =(G1+G2+G3+...+G 63 +G 64 ) / 64 Calculate the average value G of the 64 arc angles in step 3. p Step 5, according to the formula The calculated value is g, and the angularity of a single particle is PD = g / G. p The roundness of individual particles of 20 single-crystal cathode material particles was tested according to the above method, and the average value was taken as the final test result.

[0031] According to embodiments of this application, the single-particle roundness PD of the monocrystalline cathode material is 0.02~0.4. This further improves surface smoothness, thereby enhancing the electrical and safety performance of solid-state batteries, while also being easily achievable.

[0032] According to embodiments of this application, A includes at least one element selected from Al, Ti, Zr, Sr, La, Ce, Pr, Ta, W, Y, Mg, Zn, Mo, Nb, Sb, Sn, P, Cl, F, and B. This allows for further improvement of the electrochemical performance of the cathode material, and the aforementioned elements are widely available and relatively inexpensive.

[0033] According to embodiments of this application, the uniformity of edge roundness U between different particles of the single-crystal cathode material PD The value is 0.0~0.6, specifically 0.01~0.3. As an example, the uniformity of edge roundness U between different particles of a single-crystal cathode material... PD Specifically, it can be a range of 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, or any two of them. PD This value reflects the uniformity of the roundness among different particles of the cathode material. The smaller the value, the better the overall roundness and smoothness of the cathode material. A larger value indicates that there are significant differences in roundness among different particles of the cathode material. Large differences in roundness among different particles will lead to significant differences in the ion transport distance within different particles during charging and discharging in solid-state batteries. After multiple charge-discharge cycles, some particles may undergo irreversible structural changes, affecting the long-term cycle performance of the cathode material.

[0034] In this article, U PD The detection method is as follows: Test the G of 20 cathode material particles according to the method described above. p They are respectively labeled as G p1 G p2 G p3 G p20 According to the formula t=(G P1 +G P2 +G P3 +...+G P19 +G P20 The calculation of 20 single-particle G yields 20 G values. p The average value t, according to the formula The calculated value of w and the uniformity of edge roundness U between different particles are obtained. PD= w / t.

[0035] According to an embodiment of this application, the single-particle roundness S of the single-crystal cathode material is... CPIt ranges from 0.0 to 0.4, specifically from 0.05 to 0.25. As an example, the single-particle roundness S of a single-crystal cathode material... CP Specifically, the value can be 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, or any two of these ranges. A smaller value indicates better sphericity and roundness of the individual particles, and a smoother surface. A larger value indicates poorer sphericity and a rougher surface, resulting in poorer sphericity. Within the above range, single-crystal cathode materials can effectively improve the solid-solid interface contact in solid-state batteries, thereby improving the electrochemical and safety performance of the battery.

[0036] In this article, S CP The testing method is as follows: Step 1, take a CP image of a single particle under a scanning electron microscope at a magnification of 30K, and select a particle size of D... 50 ±D 50 Particles within a 20% range are designated as target particles. Step 2: Using the Metis software, 32 line segments passing through the center of each particle are drawn. The angle between adjacent line segments and the particle's center point is controlled within 11.25±5°. The starting and ending points of the line segments are located on the particle's outline. This yields 32 sets of line segment length data, labeled H1, H2, H3, ..., H... 32 Step 3, according to formula D p =(H1+H2+H3+...+H 31 +H 32 The average value D of the 32 line segment lengths is calculated by 32 / 32. p This refers to the particle size of a single particle. Step 4: According to the formula... k was calculated, and the roundness S of a single particle was obtained. CP =k / D p .

[0037] According to embodiments of this application, the uniformity of roundness U between different particles of the single-crystal cathode material CP It ranges from 0.0 to 0.3, specifically from 0.05 to 0.15. As an example, U... CP Specifically, the value can be 0.0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, or any two of these ranges. The smaller the value, the better the uniformity of particle size among different particles, indicating better single-crystalization of the cathode material, which is more conducive to improving the overall performance of solid-state batteries.

[0038] In this article, U CP The testing method is as follows: Test the D of 20 cathode material particles according to the method described above. p They are labeled as D. p1 D p2 Dp3 ... D p20 According to formula D a =(D1+D2+D3+...+D 19 +D 20 ) / 20 Calculate the average particle size D of 20 individual particles. a According to formula U CP = Calculate U CP .

[0039] According to embodiments of this application, the compressive breakage ratio (CR) of the single-crystal cathode material is 0% to 20%, specifically 0% to 15%. As an example, the CR can be 0%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, or any range between two of these. A smaller CR indicates that the cathode material is more pressure-resistant, less prone to breakage, and has higher compressive strength, effectively improving particle breakage during charging and discharging and enhancing electrical performance.

[0040] In this paper, the CR (Crippled Particle Ratio) test method after compression is as follows: Step 1, the single-crystal cathode material and electrolyte powder (such as lithium phosphorus sulfur chlorine) are mixed at a mass ratio of 7:3, and then placed in an agate mortar and mixed for five minutes to obtain a mixed powder. A pressure of 500 MPa is applied to the mixed powder. Step 2, the pressurized mixed powder is placed under a scanning electron microscope, and five different regions are randomly selected to take five photographs. Each photograph contains at least 50 particles. Step 3, the total number of particles in the five photographs is counted and recorded as n1. Simultaneously, the number of cracked particles is counted and recorded as n2. Step 4, the ratio of n2 to n1 is calculated, which is the CR, i.e., CR = n2 / n1 × 100%.

[0041] According to embodiments of this application, the Kc of the single-crystal cathode material before and after pressurization... 90 Volatility V K90 It ranges from 0 to 0.15, specifically from 0 to 0.1. As an example, V... K90 Specifically, it can be 0, 0.02, 0.04, 0.06, 0.08, 0.1, 0.12, 0.15, or a range between any two of them. V K90 The smaller the value, the less adhesion between particles. When used in solid-state batteries, this allows the solid electrolyte to be more evenly coated on the surface of the cathode material particles, reducing the exposed surface of the uncoated electrolyte layer. This, in turn, can improve ion transport, capacity, and cycle performance.

[0042] In this article, V K90 The testing method is as follows: Step 1, the single-crystal cathode material powder is tested with a particle size analyzer to obtain the D of the sample before pressure, under unpressurized conditions. 10[压前] D50[压前] and D 90[压前] Calculate K 90[压前] =(D 90[压前] -D 10[压前] ) / D 50[压前] Step 2: After applying a 5T pressure to the single-crystal cathode material, the density (D) of the compressed sample is measured using a particle size analyzer. 10[压后] D 50[压后] and D 90[压后] Calculate K 90[压后] =(D 90[压后] -D 10[压后] ) / D 50[压后] Then through formula V K90 =(K 90[压前] -K 90[压后] ) / K 90[压前] V was calculated K90 .

[0043] According to embodiments of this application, the single-crystal cathode material satisfies at least one of the following conditions: I (003) / I (104) The range is 1.2 to 3.5, specifically 1.4 to 2.8, and more specifically 1.2, 1.5, 1.8, 2.0, 2.2, 2.5, 2.8, 3.0, 3.2, 3.5, or any two of them. I (003) / (I (003) +I (101) +I (104) The range is 0.25 to 0.85, specifically 0.35 to 0.75, and more specifically 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, or any two of these ranges. Among them, I (003) I (101) I (104) These are the absolute intensity values ​​of the (003) peak, (101) peak, and (104) peak in the XRD diffraction pattern of the single-crystal cathode material, respectively.

[0044] Specifically, I (003) / I (104) A higher Li / Ni ratio indicates a lower degree of Li / Ni mixing, resulting in a more ordered layered structure in the cathode material. This is beneficial for lithium-ion insertion / extraction during charge / discharge processes, thus improving the cathode material's capacity and cycle performance. Meanwhile, I... (003) / (I (003) +I (101) +I (104)Within a suitable range, this indicates that the cathode material has a more ideal crystal structure and a more stable structure, which can effectively alleviate the volume change caused by phase transition during charging and discharging, thereby effectively improving cycle performance.

[0045] In this article, the I of single-crystal cathode material (003) I (101) and I (104) The testing method is as follows: The full spectrum is obtained using an X-ray diffractometer with a scanning range of 10° to 80°, a scanning step size of 0.02°, and a scanning speed of 2° / min. The absolute values ​​of the intensity of the (003) peak, (101) peak, and (104) peak are then obtained directly by fitting the full spectrum data with SmartlabStudio II. The 2θ angles of the (003) peak, (101) peak, and (104) peak are located at 18.0°±1.0°, 36.5°±1.0°, and 44.3°±1.0°, respectively.

[0046] According to embodiments of this application, the Li / Ni mixture of the single-crystal cathode material is 0% to 2.0%, specifically 0% to 1.5%. As an example, the Li / Ni mixture of the single-crystal cathode material can specifically be 0%, 0.2%, 0.4%, 0.6%, 0.7%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, or any range between two of these. A Li / Ni mixture within the above range indicates fewer disordered states in the cathode material's crystal structure, which is beneficial for lithium ion migration in the layered structure, reduces interfacial impedance and polarization effects, minimizes the loss of reversible capacity in the cathode material, and thus improves the cycle and rate performance of the cathode material.

[0047] In this paper, the Li / Ni hybridization of the single-crystal cathode material can be obtained by measuring the full spectrum using an X-ray diffractometer (which is the same as the XRD detection method described above). Then, by fitting the data using Smartlab Studio II, the Li / Ni hybridization data can be directly obtained, i.e., how many nickel ions occupy the 3b position of the lithium layer.

[0048] A second aspect of this application provides a method for preparing the aforementioned single-crystal cathode material. According to embodiments of this application, the method includes: S10: Under the condition of rotating a first mixture containing a nickel-cobalt-manganese precursor, a first lithium salt and a first additive, the first mixture is pre-sintered to obtain a first process product.

[0049] In this step, pre-sintering under rotating conditions allows for sufficient and uniform contact between the first lithium salt and the precursor, enabling the first lithium salt to melt more uniformly within the precursor. During the reaction of single-crystal particle development, the temperature difference at different locations on the surface of the single particle is smaller, and the growth rates in different directions are more similar during growth. Therefore, the final grown single-crystal particles are more rounded and have a smoother surface morphology.

[0050] According to embodiments of this application, at least one of a high-speed mixer, a milling machine, or a ball mill can be used to mix the nickel-cobalt-manganese precursor, the first lithium salt, and the first additive. This results in simple operation and uniform mixing.

[0051] According to embodiments of this application, the pre-sintering heating rate is 2℃ / min to 10℃ / min, specifically 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, or any range between two of these. This heating rate promotes uniform temperature increase, avoids excessively high local temperatures, facilitates the temperature and reaction between the first lithium salt and the precursor, and improves the structural integrity and particle uniformity of the cathode material.

[0052] According to embodiments of this application, the pre-sintering temperature is 500℃~850℃, specifically 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, or any range between two of these. This temperature range effectively promotes lithium salt melting and penetration, and uniform reaction of the precursor, thereby improving the structural integrity, particle uniformity, particle roundness, and surface smoothness of the cathode material.

[0053] According to embodiments of this application, the pre-sintering holding time is 4h to 14h, specifically 4h, 6h, 8h, 10h, 12h, 14h, or any range between two of these. This time range allows the precursor and lithium salt to fully contact and undergo a preliminary reaction, ensuring a complete reaction without wasting time.

[0054] According to embodiments of this application, the rotation speed is 100 rpm to 2400 rpm, specifically 100 rpm, 500 rpm, 800 rpm, 1200 rpm, 1600 rpm, 2000 rpm, 2400 rpm, or any range between two of these. This rotation speed range allows for sufficient and uniform contact between the precursor and lithium salt at different locations, minimizing temperature differences at different locations during the reaction stage, and thus enabling the growth of round and smooth particles. If the rotation speed is too slow, the precursor and lithium salt may not achieve uniform and sufficient contact, making it impossible to grow round and smooth single crystals. If the rotation speed is too fast, it may affect the residence time of the material inside the equipment, similarly preventing uniform and sufficient contact between the precursor and lithium salt, hindering grain growth at an appropriate rate, and making it difficult to maintain a round and smooth particle morphology.

[0055] According to embodiments of this application, after pre-sintering, the temperature is gradually cooled to below 200°C, specifically through slow, natural cooling. This helps reduce structural defects, release stress, and reduce crack formation, while also improving surface structure stability and particle uniformity.

[0056] According to embodiments of this application, the pre-sintering atmosphere is at least one of air, oxygen, and nitrogen. This ensures a complete and smooth reaction.

[0057] According to an embodiment of this application, the pre-sintering is carried out in a rotary kiln. This effectively ensures that the first mixture is sintered under rotating conditions, thereby effectively improving the surface smoothness, particle roundness, and particle uniformity of the cathode material particles.

[0058] According to embodiments of this application, the nickel-cobalt-manganese precursor can be Ni x Co y Mn z (OH)2 and Ni x Co y Mn z O p At least one of the following, wherein 0.8≤x≤1.0, 0.0≤y≤0.2, 0.0≤z≤0.2, and 0.7≤p≤1.6. This facilitates the acquisition of cathode materials with the target composition.

[0059] According to an embodiment of this application, the first lithium salt is lithium hydroxide. Lithium hydroxide has a melting point of approximately 500°C or lower and exhibits stronger reactivity. Using lithium hydroxide in the pre-sintering step allows for efficient lithiation at lower temperatures, thereby further promoting closer convergence of growth rates in different directions during growth. This results in more rounded single-crystal particles with smoother surface morphology, and also helps reduce the formation of impurity phases, improves the purity of the cathode material, enhances structural stability, and is more beneficial to battery performance.

[0060] According to embodiments of this application, the first additive may be H2WO4, WO3, NaOH, Al(OH)3, Al2O3, ZrO2, Nb2O5, LiNbO3, CeO2, Sr(OH)2, Sr(NO3)2, SrCO3, SrTiO3, La2O3, La(OH)3, Pr2O3, or Pr6O. 11 At least one of the following: Nd2O3, Ta2O5, V2O5, Rh2O3, RuO4, RuO2, GaAlP, GaN, Ga2O3, In2O3, Y2O3, MgO, MgCl2, MgF2, Mg(OH)2, MgCO3, ZnO, MoO3, Sb2O5, SnO2, TiB2, H3BO3, H2ZrF6, YF3, and LiF.

[0061] According to embodiments of this application, after pre-sintering and cooling, the obtained product can be subjected to weak dissociation. Specifically, weak dissociation refers to crushing using crushing equipment such as colloid mills and rotary mills to reduce adhesion between single crystal particles. This can improve particle uniformity.

[0062] S20: The first process product and an optional second lithium salt are mixed and subjected to a first sintering to obtain the second process product.

[0063] In this step, the optional second lithium salt means that the second lithium salt can be added as needed. Specifically, if sufficient lithium salt has been added in step S10 (i.e., the amount of the first lithium salt is all the lithium salt required for the reaction), the second lithium salt does not need to be added in this step; if a portion of lithium salt has been added in step S10 (i.e., the amount of the first lithium salt is part of the lithium salt required for the reaction), the remaining lithium salt is supplemented in this step, that is, the second lithium salt is added accordingly.

[0064] According to embodiments of this application, based on the total mass of the first lithium salt and the second lithium salt, the mass percentage of the first lithium salt is 50% to 100%, specifically 60% to 80%, and more specifically, 50%, 60%, 70%, 80%, 90%, 100%, or any range between two of these. Specifically, adding a portion of lithium salt in the pre-sintering step facilitates uniform mixing of the lithium salt and the precursor, and also alleviates corrosion of the rotatable sintering equipment (such as a rotary kiln), extending the service life of the sintering equipment. If the proportion of the first lithium salt is too low, the mixing with the precursor will be insufficient, and the mixture may exhibit lithium deficiency or even absence in some areas. In areas lacking or without lithium during the pre-sintering process, the lithium salt cannot uniformly penetrate the precursor particles, resulting in uneven growth of the single crystal particles and anisotropic non-uniform growth. Consequently, the morphology of the final single crystal particles is difficult to maintain a rounded and smooth shape, with poor edge roundness.

[0065] According to embodiments of this application, when a second lithium salt is added in this step, at least one of a high-speed mixer, a plow, or a ball mill can be used to mix the first process product and the second lithium salt. This results in simple operation and uniform mixing.

[0066] According to embodiments of this application, the first sintering includes sequentially performing a first-stage sintering and a second-stage sintering. This improves the structural uniformity of the cathode material, promotes crystal structure development, and consequently enhances the structural stability and electrochemical performance of the cathode material.

[0067] According to embodiments of this application, the heating rate of the sintering stage is 3°C / min to 10°C / min, specifically 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, or any range between two of these. This heating rate facilitates uniform temperature increase, avoids localized overheating or undercooling, and thus helps reduce structural defects in the cathode material and improve its electrochemical performance.

[0068] According to embodiments of this application, the sintering temperature is 400℃~700℃, specifically 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, or any range between two of these. Within the above temperature range, a uniform lithium intercalation reaction can be completed, reducing local component segregation and thus improving the uniformity and electrochemical performance of the cathode material.

[0069] According to embodiments of this application, the holding time for the sintering stage is 1 hour to 7 hours, specifically 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or any range between two of these. This time range allows the reaction to proceed fully without wasting time.

[0070] According to embodiments of this application, the heating rate of the two-stage sintering is 2℃ / min to 8℃ / min, specifically 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, or any range between two of these. This heating rate facilitates uniform temperature increase, avoids localized overheating or undercooling, and thus helps reduce structural defects in the cathode material and improve its electrochemical performance.

[0071] According to embodiments of this application, the two-stage sintering temperature is 700℃~950℃, specifically 700℃, 720℃, 750℃, 780℃, 800℃, 820℃, 850℃, 880℃, 900℃, 920℃, 950℃, or any range between two of these. This temperature range promotes the growth of single-crystal cathode materials at a suitable rate, resulting in cathode materials with fewer structural defects and better electrochemical performance.

[0072] According to embodiments of this application, the holding time for the two-stage sintering is 5h to 15h, specifically 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 3h, 14h, 15h, or any range between two of these. This time range allows the reaction to proceed fully without wasting time.

[0073] According to an embodiment of this application, the atmosphere for the first sintering is at least one of air, oxygen, and nitrogen. This facilitates the smooth progress of the reaction.

[0074] According to embodiments of this application, the second lithium salt includes at least one of LiOH and Li₂CO₃. This results in high reactivity, which is beneficial for improving the structural stability and electrochemical performance of the obtained cathode material.

[0075] According to embodiments of this application, after the first sintering, a cooling and strong dissociation treatment may be performed. Specifically, strong dissociation refers to using a crushing device such as an air jet mill to perform a high-intensity and thorough crushing treatment on the sintered product. By adjusting the parameters of the crushing device, the density of the sample after crushing is controlled. 50 Within a suitable range, the adhesion between single crystal particles is reduced, thereby improving the independence of single crystal particles.

[0076] S30: The second process product and the second additive are mixed and subjected to a second sintering to obtain the third process product.

[0077] According to embodiments of this application, at least one of a high-speed mixer, a plow, or a ball mill can be used to mix the second process product and the second additive. This results in simple operation and uniform mixing.

[0078] According to embodiments of this application, the heating rate of the second sintering is 2°C / min to 8°C / min, specifically 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, or any range between two of these. This heating rate facilitates uniform temperature increase, avoids localized overheating or undercooling, and thus helps reduce structural defects in the cathode material and improve its electrochemical performance.

[0079] According to embodiments of this application, the second sintering temperature is 630°C to 760°C, specifically 630°C, 650°C, 680°C, 700°C, 720°C, 740°C, 760°C, or any range between two of these. This temperature range promotes a complete reaction, resulting in a higher reaction rate, fewer side reactions, fewer structural defects in the obtained cathode material, and better electrochemical performance.

[0080] According to embodiments of this application, the holding time for the second sintering is 4 hours to 10 hours, specifically 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, or any range between two of these. This time range allows the reaction to proceed sufficiently without wasting time.

[0081] According to an embodiment of this application, the atmosphere for the second sintering is at least one of air, oxygen, and nitrogen. This facilitates the smooth progress of the reaction.

[0082] According to embodiments of this application, the second additive includes H2WO4, WO3, NaOH, Al(OH)3, Al2O3, ZrO2, Nb2O5, LiNbO3, CeO2, Sr(OH)2, Sr(NO3)2, SrCO3, SrTiO3, La2O3, La(OH)3, Pr2O3, and Pr6O. 11 The cathode material contains at least one of the following: Nd₂O₃, Ta₂O₅, V₂O₅, Rh₂O₃, RuO₄, RuO₂, GaAlP, GaN, Ga₂O₃, In₂O₃, Y₂O₃, MgO, MgCl₂, MgF₂, Mg(OH)₂, MgCO₃, ZnO, MoO₃, Sb₂O₅, SnO₂, TiB₂, H₃BO₃, H₂ZrF₆, YF₃, CoO, Co₂O₃, Co₃O₄, Co(OH)₂, Co(OH)₃, CoOOH, and CoF₃. This process stabilizes the surface and shallow surface structure of the cathode material particles, constructing a protective layer. Simultaneously, it reduces residual alkali in the cathode material, which is beneficial for capacity utilization and cycle life improvement.

[0083] According to embodiments of this application, after the second sintering, dissociation and crushing can also be performed. Specifically, dissociation and crushing refers to using equipment such as a rotary mill or colloid mill to crush the sintered product, thereby reducing the adhesion between single crystal particles and increasing particle independence.

[0084] S40: The third process product and the third additive are mixed and subjected to a third sintering to obtain the single-crystal cathode material.

[0085] According to embodiments of this application, at least one of a high-speed mixer, a plow, or a ball mill can be used to mix the third process product and the third additive. This results in simple operation and uniform mixing.

[0086] According to embodiments of this application, the heating rate of the third sintering is 2℃ / min to 8℃ / min, specifically 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, or any range between two of these. This heating rate facilitates uniform temperature increase, avoids localized overheating or undercooling, and thus helps reduce structural defects in the cathode material and improve its electrochemical performance.

[0087] According to embodiments of this application, the third sintering temperature is 300℃~550℃, specifically 300℃, 320℃, 350℃, 380℃, 400℃, 420℃, 450℃, 480℃, 500℃, 520℃, 550℃, or any range between two of these. This temperature range promotes a complete reaction, resulting in a higher reaction rate, fewer side reactions, fewer structural defects in the obtained cathode material, and better electrochemical performance.

[0088] According to embodiments of this application, the holding time for the third sintering is 4h to 10h, specifically 4h, 5h, 6h, 7h, 8h, 9h, 10h, or any range between two of these. This time range allows the reaction to proceed fully without wasting time.

[0089] According to an embodiment of this application, the atmosphere for the third sintering is at least one of air, oxygen, and nitrogen. This facilitates the smooth progress of the reaction.

[0090] According to embodiments of this application, the third additive includes H2WO4, WO3, NaOH, Al(OH)3, Al2O3, Nb2O5, LiNbO3, CeO2, Sr(OH)2, Sr(NO3)2, SrCO3, SrTiO3, La2O3, La(OH)3, Pr2O3, and Pr6O. 11 The cathode material contains at least one of the following: Nd₂O₃, Ta₂O₅, V₂O₅, Rh₂O₃, RuO₄, RuO₂, GaAlP, GaN, Ga₂O₃, In₂O₃, Y₂O₃, MgO, MgCl₂, MgF₂, Mg(OH)₂, MgCO₃, ZnO, MoO₃, Sb₂O₅, SnO₂, TiB₂, H₃BO₃, H₂ZrF₆, YF₃, LiF, lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, lithium aluminum germanium phosphate, and lithium aluminum titanium phosphate. This effectively improves the surface structural stability of the cathode material, reduces side reactions, and enhances the electrochemical performance of the cathode material.

[0091] According to embodiments of this application, after the third sintering is completed, the product can also be sieved. The mesh size of the sieve used for sieving can be between 100 and 600 mesh, more specifically, between 300 and 500 mesh. The purpose of sieving is to remove foreign matter and large particles that may be introduced during the production process.

[0092] In the method described in this application, pre-calcination is performed while maintaining the rotation of the first mixture, which effectively improves the contact between the lithium salt and the precursor. High-temperature sintering thereafter yields a single-crystal cathode material product with high roundness and a smooth surface. The prepared cathode material exhibits microscopic characteristics such as low cation mixing and better layered structure, and macroscopically displays narrow particle size distribution, good sphericity, good surface smoothness, high roundness, and high compressive strength. When used in solid-state batteries, the electrolyte can better coat the surface of the cathode material particles, which is beneficial for ion transport and improves the battery's electrical and safety performance.

[0093] A third aspect of this application provides a positive electrode sheet. According to embodiments of this application, the positive electrode sheet comprises the aforementioned monocrystalline positive electrode material. This positive electrode sheet possesses all the characteristics and advantages of the aforementioned monocrystalline positive electrode material; when used in solid-state batteries, it is less prone to grain boundary cracking, exhibits superior ion / electron transport performance, and has lower barrier properties, effectively mitigating performance degradation.

[0094] According to embodiments of this application, the positive electrode sheet may include a positive current collector and a positive electrode material layer disposed on at least one side of the positive current collector. The positive electrode material may include the aforementioned single-crystal positive electrode material, positive electrode conductive agent, and positive electrode binder, and may also include necessary positive electrode additives (including but not limited to lithium supplementation agents, film-forming additives, etc.) as needed.

[0095] In some embodiments, the positive current collector may include a metal foil or a composite positive current collector. For example, the metal foil may be aluminum foil. The composite positive current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. For example, the composite negative current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, etc.) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.).

[0096] In some embodiments, the type of positive electrode binder is not particularly limited, and those skilled in the art can choose according to actual needs. As some specific embodiments, the positive electrode binder includes at least one of polyvinylidene fluoride (PVDF), polyimide (PI), polyacrylic acid (PAA), and styrene-butadiene rubber (SBR).

[0097] In some embodiments, the positive electrode conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0098] In a fourth aspect, this application provides a lithium-ion battery. According to an embodiment of this application, the lithium-ion battery includes the aforementioned single-crystal cathode material or the aforementioned cathode sheet. This lithium-ion battery possesses all the features and advantages of the aforementioned single-crystal cathode material and the aforementioned cathode sheet, which will not be elaborated upon here.

[0099] According to the embodiments of this application, it can be understood that there is no particular limitation on the specific type of battery, which can be a primary battery or a secondary battery; the shape of the battery can be a cylindrical battery, a square battery or other arbitrary shape batteries, and according to the outer packaging, the battery can be a hard-shell battery, a soft-pack battery, etc.

[0100] According to embodiments of this application, the lithium-ion battery is an all-solid-state battery. Specifically, using the aforementioned single-crystal cathode material in a solid-state battery can effectively improve the solid-solid interface contact, reduce impedance, and enhance ion / electron transport performance. The electrolyte can also better coat the surface of the highly spherical single-crystal cathode material particles, improving the electrical performance of the cathode material and thus providing the capacity and cycle performance of the solid-state battery.

[0101] Typically, a solid-state battery includes the positive electrode, negative electrode, and solid electrolyte membrane mentioned earlier. During charging and discharging, lithium ions repeatedly insert and extract between the positive and negative electrodes. The solid electrolyte membrane, positioned between the positive and negative electrodes, primarily serves to prevent short circuits between the electrodes while allowing lithium ions to pass through.

[0102] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one side surface of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material.

[0103] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.).

[0104] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, etc. Silicon-based materials may include at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include at least one of elemental tin, tin oxide compounds, and tin alloys.

[0105] In some embodiments, the negative electrode active material layer may optionally include a negative electrode binder. The negative electrode binder may include at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0106] In some embodiments, the negative electrode active material layer may optionally include a negative electrode conductive agent. The negative electrode conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0107] In some embodiments, the negative electrode active material layer may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0108] In some embodiments, the specific type of solid electrolyte membrane is not particularly limited and can be selected according to actual needs. For example, the solid electrolyte membrane may include oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, polymer solid electrolytes, etc. The solid electrolyte membrane can be disposed as a separate membrane layer between the positive and negative electrode plates, or it can be laminated onto at least one side of the positive electrode plate or at least one side of the negative electrode plate.

[0109] In some embodiments, the lithium-ion battery described above can be a single battery cell, a battery module, or a battery pack. The number of single battery cells contained in a battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module. The number of battery modules contained in a battery pack can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery pack.

[0110] In a fifth aspect, this application provides an electrical device. According to embodiments of this application, the electrical device includes the aforementioned single-crystal cathode material, the aforementioned cathode sheet, or the aforementioned lithium-ion battery.

[0111] According to embodiments of this application, the specific type of electrical device is not particularly limited and can be any device that uses the aforementioned lithium-ion battery as a power source or energy storage unit. As examples, electrical devices include, but are not limited to, electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), mobile terminals (e.g., mobile phones, laptops, game consoles, wearable devices, etc.), drones, aerospace equipment, satellites, ships, energy storage systems, etc.

[0112] It is understandable that, in addition to the battery mentioned above, the electrical device also includes necessary structures and components, all of which can be made with reference to conventional technologies. For example, an electric vehicle may include a body, chassis, tires, navigation system, radar system, steering system, braking system, lubrication system, cooling system, driving system, etc., which will not be described in detail here.

[0113] The embodiments of this application are described in detail below.

[0114] Example 1: (1) Lithium salt LiOH and nickel-cobalt-manganese precursor Ni 0.95 Co 0.04 Mn 0.01 The total mass of (OH)2, ZrO2, and Nb2O5 was calculated according to the ratio of n(Li):[n(Ni)+n(Co)+n(Mn)]:n(Zr):n(Nb) = 1.04:1:0.002:0.002. Then, all the nickel-cobalt-manganese precursor Ni was... 0.95 Co 0.04 Mn 0.01 (OH)₂, ZrO₂, and Nb₂O₅, along with a portion of lithium salt LiOH, are mixed. The mass of LiOH added in this step is 70% of the calculated total mass. Under an oxygen atmosphere, the temperature is increased to 700℃ at a rate of 5℃ / min and held for 8 hours at a rotary kiln speed of 1200 rpm. The temperature is then gradually reduced to room temperature. The pre-sintered product is subjected to weak dissociation using a rotary mill or colloid mill to obtain the first-process product.

[0115] (2) After mixing the first process product with the remaining 30% of lithium salt LiOH from step (1), the temperature is increased to 550°C at a rate of 5°C / min and held for 3 hours. Then the temperature is increased to 850°C at a rate of 3°C / min and held for 10 hours. After that, the temperature is gradually reduced to room temperature and strong dissociation is carried out using an air jet mill to obtain the second process product.

[0116] (3) The second process product, the second additive Co(OH)2 and Al2O3 are uniformly mixed in the ratio of [n(Ni)+n(Co)+n(Mn)]:n(Co):n(Al)=1:0.02:0.001. Under an oxygen atmosphere, the temperature is increased to 700℃ at 5℃ / min and kept at the temperature for 6h. Then the temperature is gradually reduced to room temperature. The product is dissociated using a colloid mill to obtain the third process product.

[0117] (4) The third process product, the third additive H3BO3 and LiNbO3 are uniformly mixed in the ratio of [n(Ni)+n(Co)+n(Mn)]:n(B):n(Nb)=1:0.001:0.005. Under air atmosphere, the temperature is raised to 350℃ at 6℃ / min and kept at the temperature for 6h. Then the temperature is gradually lowered to room temperature. After the product is sieved, the single crystal cathode material is obtained.

[0118] Examples 2-21: Same as Example 1, with differences shown in Tables 1 and 2.

[0119] Comparative Examples 1 to 5: Same as Example 1, with differences shown in Tables 1 and 2.

[0120] Table 1

[0121] Table 2

[0122] Performance testing: (1) Particle size test: laser particle size analyzer.

[0123] (2) SEM morphology and CP map test: SU8600 scanning electron microscope of ELIONIX Corporation, Japan. Then, the roundness, roundness uniformity, smoothness and smoothness uniformity of the cathode material were calculated according to the method described above.

[0124] (3) XRD testing: A SmartLab 9kW X-ray diffractometer from Rigaku Corporation, Japan. The specific operating procedures are as described above. I can be calculated based on the obtained XRD pattern. (003) I (101) and I (104) The Li / Ni hybrid arrangement was obtained by calculation using the fitting refinement software Smartlab Studio II.

[0125] (4) Electrochemical performance testing: The specific process for preparing the mold battery is as follows: Preparation of the composite cathode layer: The single-crystal cathode material, sulfide electrolyte (lithium phosphorus sulfur chloride), and conductive agent (vapor-grown carbon fiber, VGCF) prepared in the above examples and comparative examples were ground and mixed three times in a mill at a mass ratio of 70:27:3, with each mixing time lasting 2 minutes, to obtain a uniform composite cathode powder. An appropriate amount of the composite cathode powder was introduced into a 10mm diameter mold and pressed at 450MPa using a powder press to obtain the composite cathode layer.

[0126] Electrolyte layer preparation: Take an appropriate amount of sulfide electrolyte (lithium phosphorus sulfur chloride) powder, put it into a mold, and press it at 100MPa using a powder tablet press to obtain the electrolyte layer.

[0127] Battery Assembly: In an argon-filled glove box with both water and oxygen content less than 5 ppm, the composite positive electrode layer, electrolyte layer, and negative electrode sheet were assembled into a mold. The assembled mold was then placed in a pressure-holding device, and a pressure of 100 MPa was applied using a powder press to obtain a testable mold battery. A lithium-indium alloy negative electrode sheet was used, with a diameter of 10 mm. The electrochemical performance of the mold battery was then tested using the Shenzhen Xinwei Battery Testing System, with a nominal specific capacity set at 175 mAh / g.

[0128] Capacity, rate performance, and cycle performance testing: The charge / discharge voltage range was controlled at 3.7-1.9V. At room temperature, the mold battery was cycled twice at 0.1C, and then 100 times at 1C. The first 0.1C discharge capacity and efficiency were used to evaluate the material's first 0.1C discharge specific capacity and efficiency. The rate performance was evaluated by the ratio of the first 1C discharge specific capacity to the first 0.1C discharge specific capacity. The ratio of the 100th 1C discharge capacity to the first 1C discharge capacity is the 1C capacity retention rate, which is used to evaluate the material's cycle performance.

[0129] Table 3

[0130] The data above shows that when the roundness of the cathode material is in the range of 0.0 to 0.8, the battery capacity, cycle performance, and rate performance are all good.

[0131] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0132] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0133] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A single-crystal cathode material, characterized in that, include: Li 1+a Ni x Co y Mr z A m O2, Wherein, 0.1≤a≤0.1, 0.8≤x≤1.0, 0.0≤y≤0.2, 0.0≤z≤0.2, and 0.0<m<0.1; A includes at least one of the following elements: Al, Ti, Zr, Na, Sr, K, Ca, La, Ce, Pr, Nd, Ta, V, Rh, Ru, Ga, In, Y, Cu, Mg, Zn, Mo, Nb, Sb, P, Sn, W, Cl, F, and B. The single-particle roundness PD of the single-crystal cathode material is 0.0~0.

8.

2. The single-crystal cathode material according to claim 1, characterized in that, At least one of the following conditions must be met: The single-particle roundness PD of the single-crystal cathode material is 0.02~0.4; A includes at least one of the elements Al, Ti, Zr, Sr, La, Ce, Pr, Ta, W, Y, Mg, Zn, Mo, Nb, Sb, Sn, P, Cl, F, and B.

3. The single-crystal cathode material according to claim 1, characterized in that, The uniformity of edge roundness among different particles of the single-crystal cathode material U PD The value is 0.0~0.6, preferably 0.01~0.

3.

4. The single-crystal cathode material according to claim 1, characterized in that, At least one of the following conditions must be met: The single-particle roundness S of the single-crystal cathode material CP The value is 0.0~0.4, preferably 0.05~0.25; The uniformity of roundness among different particles of the single-crystal cathode material U CP The value is 0.0~0.3, preferably 0.05~0.

15.

5. The single-crystal cathode material according to claim 1, characterized in that, At least one of the following conditions must be met: The proportion of granules after compression of the single-crystal cathode material is 0%~20%, preferably 0%~15%; K before and after pressurization of the single-crystal cathode material 90 Volatility V K90 The value is 0~0.15, preferably 0~0.

1.

6. The single-crystal cathode material according to claim 1, characterized in that, At least one of the following conditions must be met: I (003) / I (104) The value is 1.2~3.5, preferably 1.4~2.8; I (003) / (I (003) +I (101) +I (104) The value is 0.25~0.85, preferably 0.35~0.75; Among them, I (003) I (101) I (104) These are the absolute intensity values ​​of the (003) peak, (101) peak, and (104) peak in the XRD diffraction pattern of the single-crystal cathode material, respectively.

7. The single-crystal cathode material according to claim 1, characterized in that, The Li / Ni mixture of the single-crystal cathode material is 0%~2.0%, preferably 0%~1.5%.

8. A method for preparing the single-crystal cathode material according to any one of claims 1 to 7, characterized in that, include: The first mixture containing nickel-cobalt-manganese precursor, first lithium salt and first additive is pre-sintered under rotating conditions to obtain the first process product; The first process product and an optional second lithium salt are mixed and subjected to a first sintering to obtain the second process product; The second processed product and the second additive are mixed and subjected to a second sintering to obtain the third processed product; The third process product and the third additive are mixed and subjected to a third sintering to obtain the single-crystal cathode material; Wherein, the first lithium salt is lithium hydroxide, and based on the total mass of the first lithium salt and the second lithium salt, the mass percentage of the first lithium salt is 50% to 100%.

9. The method according to claim 8, characterized in that, Based on the total mass of the first lithium salt and the second lithium salt, the mass percentage of the first lithium salt is 60% to 80%.

10. The method according to claim 8, characterized in that, At least one of the following conditions must be met: The heating rate of the pre-sintering is 2℃ / min to 10℃ / min; The pre-sintering temperature is 500℃~850℃; The pre-sintering holding time is 4h~14h; The pre-sintering atmosphere is at least one of air, oxygen, and nitrogen; The pre-sintering is carried out in a rotary kiln; The rotation speed is 100 rpm to 2400 rpm.

11. The method according to claim 8, characterized in that, The first sintering includes sequential first-stage sintering and second-stage sintering, and satisfies at least one of the following conditions: The heating rate of the first sintering section is 3℃ / min~10℃ / min; The sintering temperature of the first section is 400℃~700℃; The holding time for the first sintering stage is 1 hour to 7 hours; The heating rate for the two-stage sintering is 2℃ / min to 8℃ / min; The temperature for the two-stage sintering is 700℃~950℃; The holding time for the two-stage sintering is 5h~15h; The atmosphere for the first sintering is at least one of air, oxygen, and nitrogen.

12. The method according to claim 8, characterized in that, At least one of the following conditions must be met: The heating rate for the second sintering is 2℃ / min to 8℃ / min; The second sintering temperature is 630℃~760℃; The second sintering holding time is 4h~10h; The atmosphere for the second sintering is at least one of air, oxygen, and nitrogen.

13. The method according to claim 8, characterized in that, At least one of the following conditions must be met: The heating rate of the third sintering is 2℃ / min to 8℃ / min; The temperature of the third sintering is 300℃~550℃; The holding time for the third sintering is 4h~10h; The atmosphere for the third sintering is at least one of air, oxygen, and nitrogen.

14. The method according to claim 8, characterized in that, At least one of the following conditions must be met: The nickel-cobalt-manganese precursor is Ni x Co y Mn z (OH)2, Ni x Co y Mn z O p At least one of the following, wherein 0.8≤x≤1.0, 0.0≤y≤0.2, 0.0≤z≤0.2, and 0.7≤p≤1.6; The second lithium salt includes at least one of LiOH and Li2CO3; The first additive includes H2WO4, WO3, NaOH, Al(OH)3, Al2O3, ZrO2, Nb2O5, LiNbO3, CeO2, Sr(OH)2, Sr(NO3)2, SrCO3, SrTiO3, La2O3, La(OH)3, Pr2O3, and Pr6O. 11 At least one of the following: Nd₂O₃, Ta₂O₅, V₂O₅, Rh₂O₃, RuO₄, RuO₂, GaAlP, GaN, Ga₂O₃, In₂O₃, Y₂O₃, MgO, MgCl₂, MgF₂, Mg(OH)₂, MgCO₃, ZnO, MoO₃, Sb₂O₅, SnO₂, TiB₂, H₃BO₃, H₂ZrF₆, YF₃, LiF; The second additive includes H2WO4, WO3, NaOH, Al(OH)3, Al2O3, ZrO2, Nb2O5, LiNbO3, CeO2, Sr(OH)2, Sr(NO3)2, SrCO3, SrTiO3, La2O3, La(OH)3, Pr2O3, and Pr6O. 11 At least one of the following: Nd₂O₃, Ta₂O₅, V₂O₅, Rh₂O₃, RuO₄, RuO₂, GaAlP, GaN, Ga₂O₃, In₂O₃, Y₂O₃, MgO, MgCl₂, MgF₂, Mg(OH)₂, MgCO₃, ZnO, MoO₃, Sb₂O₅, SnO₂, TiB₂, H₃BO₃, H₂ZrF₆, YF₃, CoO, Co₂O₃, Co₃O₄, Co(OH)₂, Co(OH)₃, CoOOH, CoF₃; The third additive includes H2WO4, WO3, NaOH, Al(OH)3, Al2O3, Nb2O5, LiNbO3, CeO2, Sr(OH)2, Sr(NO3)2, SrCO3, SrTiO3, La2O3, La(OH)3, Pr2O3, and Pr6O. 11 At least one of the following: Nd2O3, Ta2O5, V2O5, Rh2O3, RuO4, RuO2, GaAlP, GaN, Ga2O3, In2O3, Y2O3, MgO, MgCl2, MgF2, Mg(OH)2, MgCO3, ZnO, MoO3, Sb2O5, SnO2, TiB2, H3BO3, H2ZrF6, YF3, LiF, lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, lithium aluminum germanium phosphate, and lithium aluminum titanium phosphate.

15. A positive electrode plate, characterized in that, Includes the single-crystal cathode material according to any one of claims 1 to 7.

16. A lithium-ion battery, characterized in that, It includes the single-crystal cathode material according to any one of claims 1 to 7 or the cathode sheet according to claim 15.

17. The lithium-ion battery according to claim 16, characterized in that, The lithium-ion battery is an all-solid-state battery.

18. An electrical appliance, characterized in that, The invention includes the single-crystal cathode material according to any one of claims 1 to 7, the cathode sheet according to claim 15, or the lithium-ion battery according to claim 16 or 17.

Images