Lithium-ion battery positive electrode material, preparation method and application

Abstract

The present invention discloses a lithium-ion battery positive electrode material, a preparation method and an application. By adjusting and optimizing the doping elements and doping amounts as well as the parameters of the preparation process, single crystal or single crystal-like particles are obtained, microcracks and interface side reactions are reduced, and lithium cobalt oxide with good storage, cycle and gas production performance at a voltage of 4.50V or even higher is obtained, which is suitable for the field of power batteries.

Description

Technical Field

[0001] The present disclosure relates to the technical field of lithium-ion battery positive electrode materials, and in particular to lithium-ion battery positive electrode materials, preparation methods, and applications. Background Art

[0002] Rechargeable lithium-ion batteries are a new generation of green energy storage batteries, boasting outstanding advantages such as high power density, high voltage, high energy density, no memory effect, stable cycling, and long life. They have been widely used in products such as mobile phones, computers, new energy vehicles, smart networking, and distributed energy storage. There are many types of lithium-ion batteries, primarily composed of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium nickel oxide, lithium nickel cobalt manganese oxide, and lithium cobalt oxide / lithium nickel cobalt manganese oxide composites. Lithium cobalt oxide has the highest theoretical density, resulting in outstanding tap density and compaction density among existing materials in practical applications, leading to its widespread use in the 3C industry. Lithium nickel cobalt manganese oxide has excellent storage and cycling performance and is widely used in the power battery field. Lithium iron phosphate has excellent safety performance and is widely used in the energy storage field.

[0003] With the continuous deepening of lithium cobalt oxide research, the charging voltage of lithium cobalt oxide has been increased to 4.50V and even higher, and the specific capacity has increased to 185-187mAh / g or even higher. Lithium cobalt oxide is one of the most ideal cathode materials in the 3C industry. With the development of technology, lithium cobalt oxide has become a new development trend in the field of power batteries, and higher requirements are being placed on the energy density, storage performance, cycle performance, and gas production performance of lithium cobalt oxide.

[0004] The volume energy density of lithium-ion batteries = discharge capacity × discharge voltage platform × compaction density. Currently, the volume energy density of ternary nickel cobalt manganese oxide batteries has been upgraded from 5 series to 9 series. However, the lower discharge platform and relatively low compaction density of the ternary 9 series limit the further improvement of the energy density of the ternary 9 series. High-voltage lithium cobalt oxide above 4.5V has a high discharge platform of 4.2g / cm 3 The compacted electrode has a volume energy density greater than the ternary 9 series, and has broad application potential in the field of power batteries. However, compared with the 3C field, the power electric field has higher requirements for battery storage, gas production, and stability.

[0005] When the voltage of lithium cobalt oxide increases from 4.2V to 4.5V, more lithium ions are released from the lattice, which will cause structural instability; the degree of lithium desorption on the surface of the material becomes higher, and the structural phase change extends from the surface of the material to the interior of the particles; due to the obvious overlap of the energy band structures of cobalt and oxygen, the dissolution of cobalt and the precipitation of oxygen will be accelerated under high voltage, resulting in intensified interfacial side reactions, worsening storage and gas production, and thus affecting the actual application of lithium cobalt oxide in the field of power batteries.

[0006] In order to overcome the above problems, the doping coating method is usually adopted at present, and the coating and sintering are carried out under high temperature conditions. The coating material can absorb excess lithium and reduce residual lithium, which helps to improve the high-temperature safety performance of the material and reduce gas production. However, under high voltage conditions, as the number of lithium ions released increases, the valence of cobalt is prone to increase, and it is easy to react with the electrolyte, causing cobalt to dissolve, resulting in capacity attenuation and deterioration of storage performance.

[0007] Therefore, it is necessary to provide a new optimized process to reduce microcracks, reduce interface side reactions, reduce gas production, and improve storage performance, which is suitable for lithium cobalt oxide at 4.50V or even higher voltages.

[0008] In view of this, the present disclosure is proposed. Summary of the Invention

[0009] The purpose of the present disclosure is to provide a lithium-ion battery positive electrode material, preparation method and application, and to provide a lithium cobalt oxide that has excellent storage performance at a voltage above 4.50V and can be better applied in the field of power batteries.

[0010] The present disclosure is achieved as follows:

[0011] In a first aspect, the present disclosure provides a lithium-ion battery positive electrode material, comprising large particles and small particles,

[0012] The large particles include the general formula Li a Co 1-b1-b2-b3-b Ni b3 Mn b2 Al b1 Q b The large particle core of O2 is coated with a general formula T e E f O g The cladding layer;

[0013] The small particles include the general formula Li c Co 1-d1-d2-d3-d Ni d3 Mn d2 Al d1 Q′ d The surface of the small particle core of O2 is coated with a general formula T e E f O g The cladding layer;

[0014] The median particle size of the large particle core is 18 μm to 22 μm, the median particle size of the small particle core is 4 μm to 6 μm, the molar ratio of the small particles to the large particles is 0.1 to 0.5, the large particle core is a layered single crystal structure, and the small particle core is a layered single crystal or layered single crystal-like structure;

[0015] wherein, 0.98≤a≤1.02, 0.002≤b≤0.05, 0.01≤b1≤0.035, 0.003≤b2≤0.025, 0.001≤b3≤0.015, 0.98≤c≤1.01, 0.001≤d≤0.06, 0.01≤d1≤0.05, 0.003≤d2≤0.03, 0.0015≤d3≤0.02, 0.8≤e≤3, 0≤f≤3, 1.5≤g≤5, b2>b3, d2>d3, Q and Q′ are each independently selected from at least one of Mg, Y, La, Zr, Cu, Na and W; and T and E are each independently selected from at least one of Mg, B, La, St, W, Y, Zr, Ti, F, P and C.

[0016] In some embodiments, the median particle size of the large particle core is 19 μm to 20 μm, and the median particle size of the small particle core is 4.5 μm to 5.5 μm.

[0017] In some embodiments, the general formula is: (Li a Co 1-b1-b2-b3-b Ni b3 Mn b2 Al b1 Q b O2·tLi c Co 1-d1-d2-d3- d Ni d3 Mn d2 Al d1 Q′ d O2)·xT e E f O g , where 0.001≤x≤0.04, 0.12≤t≤0.45.

[0018] In some embodiments, 0.12≤t / (1+t)≤0.30.

[0019] In some embodiments, 1-d1-d2-d3-d≤1-b1-b2-b3-b.

[0020] In some embodiments, d and b satisfy d≥b.

[0021] In some embodiments, both Q and Q' include at least one of Mg, La, and Zr.

[0022] In some embodiments, the T is at least one of Mg, Al, Ti, and Zr.

[0023] In some embodiments, the E is at least one of F, P and C.

[0024] In a second aspect, the present disclosure provides a method for preparing the lithium-ion battery positive electrode material as described in any one of the aforementioned embodiments, comprising: coating, mixing the large particle core, the small particle core and the coating layer raw materials and sintering them to obtain the lithium-ion battery positive electrode material.

[0025] In some embodiments, the preparation of large-particle cores is also included: a precursor mixture containing lithium, nickel, cobalt, manganese, aluminum, and Q is sintered to obtain a large-particle core, wherein the ratio of the total molar amount of lithium to nickel, cobalt, manganese, aluminum, and Q in the precursor mixture is m1+m2, wherein m1 is 1.04 to 1.12, and m2=(N1*n1) / 3, wherein N1 is the molar amount of the Q element replacing the Co position, and n1 is the valence state of the Q element replacing the Co position.

[0026] In some embodiments, in the large particle core preparation step, the sintering temperature is 950° C. to 1100° C., the sintering time is 8 h to 14 h, and the sintering is performed in an oxygen-containing atmosphere.

[0027] In some embodiments, the preparation of small particle cores is also included: a precursor mixture containing lithium, nickel, cobalt, manganese, aluminum, and Q' is sintered to obtain large particle cores, wherein the ratio of the total molar amount of lithium to nickel, cobalt, manganese, aluminum and Q' in the precursor mixture is m3+m4, wherein m3 is 1.02~1.09, m4=(N2*n2) / 3, wherein N2 is the molar amount of the Q' element replacing the Co position, and n2 is the valence state of the Q' element replacing the Co position.

[0028] In some embodiments, in the small particle core preparation step, the sintering temperature is 850° C. to 1028° C., the time is 8 h to 14 h, and the sintering is performed in an oxygen-containing atmosphere.

[0029] In some embodiments, in the coating step, the sintering temperature is 700° C. to 1000° C., the time is 7 h to 13 h, and the sintering is performed in an oxygen-containing atmosphere.

[0030] In some embodiments, the Q-containing compound and the Q′-containing compound used in the steps of preparing the large particle core and the small particle core are both micro-nano-sized particles.

[0031] In some embodiments, the Q-containing compound used in the large particle core preparation step is at least one of a Q-containing oxide, hydroxide, and carbonate.

[0032] In some embodiments, the Q′-containing compound used in the small particle core preparation step is at least one of a Q′-containing oxide, a hydroxide, and a carbonate.

[0033] In some embodiments, the coating layer raw material includes at least two of the oxide of T, the hydroxide of T, the fluoride of T, the phosphide of T, the oxide of E, the hydroxide of E, the fluoride of E and the phosphide of E.

[0034] In a third aspect, the present disclosure provides a lithium-ion battery positive electrode, comprising the lithium-ion battery positive electrode material described in any one of the aforementioned embodiments or the lithium-ion battery positive electrode material obtained by the method described in any one of the aforementioned embodiments.

[0035] In a fourth aspect, the present disclosure provides a lithium-ion battery positive electrode, comprising the lithium-ion battery positive electrode described in the aforementioned embodiment.

[0036] In a fifth aspect, the present disclosure provides a lithium-ion battery comprising the lithium-ion battery positive electrode described in the aforementioned embodiment.

[0037] In a sixth aspect, the present disclosure provides an electrical device comprising the lithium-ion battery described in the aforementioned embodiment.

[0038] The present disclosure has the following beneficial effects:

[0039] In this disclosure, the nickel element in the large and small particle skeletons can increase capacity without destroying the structure, while manganese can stabilize the structure. The simultaneous presence of nickel and manganese changes the cobalt band structure, inhibiting cobalt dissolution to a certain extent and improving storage. Furthermore, the large particle core has a layered single crystal structure, while the small particle core has a layered single crystal or layered single crystal-like structure, which can increase the compaction density of the graded sample and improve cycling performance.

[0040] The present invention adjusts and optimizes the doping elements and doping amounts as well as the parameters of the preparation process to obtain single crystal or single crystal-like particles, reduce microcracks and reduce interface side reactions, and obtain lithium cobalt oxide suitable for the field of power batteries with good storage, circulation and gas production performance at a voltage of 4.50V or even higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 Flowchart for the preparation of cathode materials for lithium-ion batteries;

[0043] Figure 2 XRD pattern of the sample obtained in Example 1;

[0044] Figure 3This is the XRD pattern of the sample obtained in Example 2;

[0045] Figure 4 This is the SEM image of the sample obtained in Example 2;

[0046] Figure 5 This is the SEM image of large particles in Example 13.

[0047] Figure 6 This is the SEM image of large particles in comparative example 8. DETAILED DESCRIPTION

[0048] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer were followed. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially.

[0049] One embodiment of the present disclosure provides a lithium-ion battery positive electrode material, comprising large particles and small particles.

[0050] The large particles include the general formula Li a Co 1-b1-b2-b3-b Ni b3 Mn b2 Al b1 Q b The large particle core of O2 is coated with a general formula T e E f O g The cladding layer;

[0051] The small particles include the general formula Li c Co 1-d1-d2-d3-d Ni d3 Mn d2 Al d1 Q′ d The surface of the small particle core of O2 is coated with a general formula T e E f O g The cladding layer;

[0052] The median particle size of the large particle core is 18 μm to 22 μm, the median particle size of the small particle core is 4 μm to 6 μm, the molar ratio of the small particles to the large particles is 0.1 to 0.5, the large particle core is a layered single crystal structure, and the small particle core is a layered single crystal or layered single crystal-like structure;

[0053] wherein, 0.98≤a≤1.02, 0.002≤b≤0.05, 0.01≤b1≤0.035, 0.003≤b2≤0.025, 0.001≤b3≤0.015, 0.98≤c≤1.01, 0.001≤d≤0.06, 0.01≤d1≤0.05, 0.003≤d2≤0.03, 0.0015≤d3≤0.02, 0.8≤e≤3, 0≤f≤3, 1.5≤g≤5, b2>b3, d2>d3, Q and Q′ are each independently selected from at least one of Mg, Y, La, Zr, Cu, Na and W; and T and E are each independently selected from at least one of Mg, B, La, St, W, Y, Zr, Ti, F, P and C.

[0054] The positive electrode material in this embodiment is Li a Co 1-b1-b2-b3-b Ni b3 Mn b2 Al b1 Q b O2 is the general formula of large particle primary product, Li c Co 1-d1-d2-d3-d Ni d3 Mn d2 Al d1 Q′ d O2 is the general formula of small particle primary product, T e E f O g In large particles, Co, Ni, Mn, and Al are skeleton elements, and Q is a doping element; in small particles, Co, Ni, Mn, and Al are skeleton elements, and Q' is a doping element.

[0055] The present disclosure introduces Q, Q', T, and E elements, among which Co, Ni, Mn, and Al elements occupy the Co position in the positive electrode material. When Q and Q' occupy the Co position, they inhibit the change in the Co valence state and inhibit the release of O; when they occupy the Li position, they improve the channel and enhance the ability to deintercalate and deintercalate lithium ions; the doping of Q and Q' elements is beneficial to stabilizing the structure, improving the channel and enhancing the ability to deintercalate and deintercalate lithium ions, while also improving electronic conductivity. E and T elements greatly improve interface stability. In addition, the introduction of Q, Q', T, and E elements can also inhibit the generation of microcracks on the surface of the positive electrode material, thereby improving the electrical performance of the positive electrode material under high voltage.

[0056] The nickel element in the skeleton of large and small particles can increase the capacity without destroying the structure, and manganese can stabilize the structure. The simultaneous presence of nickel and manganese changes the cobalt band structure, inhibiting cobalt dissolution to a certain extent and improving storage. In addition, the manganese doping amount is greater than the nickel doping amount, and the structural stability is better. When large and small particles adopt a single crystal structure, the single crystal in this application refers to a single particle rather than a plurality of particles aggregated, which can increase the compaction density of the graded sample and improve the cycle performance. However, if there is too much nickel and manganese, the particles are easily crushed during sintering and polycrystalline is likely to appear. In particular, it is more difficult for large particles to grow, resulting in a decrease in compaction density, deterioration of the cycle, and affecting the overall performance.

[0057] In some embodiments, the median particle size of the large particle core is 19 μm to 20 μm, specifically 19 μm, 19.5 μm, 20 μm, or any value between 19 μm and 20 μm, and the median particle size of the small particle core is 4.5 μm to 5.5 μm, specifically 4.6 μm, 4.8 μm, 5 μm, 5.2 μm, 5.4 μm, 5.5 μm, or any value between 4.5 μm and 5.5 μm. The large particle core and the small particle core are beneficial to improving the compaction density of the electrode within this range. In addition, the type and doping amount of the doping element in the large particle core and the small particle core can be the same or different. When the type and doping amount of the doping element are different, or the concentration of the core and the coating layer are different, a concentration gradient will be formed in the positive electrode material, which is beneficial to improving the battery capacity and cycle performance.

[0058] In some embodiments, the general formula is: (Li a Co 1-b1-b2-b3-b Ni b3 Mn b2 Al b1 Q b O2·tLi c Co 1-d1-d2-d3- d Ni d3 Mn d2 Al d1 Q′ d O2)·xT e E f O g , where 0.001≤x≤0.04, 0.12≤t≤0.45.

[0059] In some embodiments, 0.12≤t / (1+t)≤0.30.

[0060] When t / (1+t)>0.30, the cycle performance, gas production performance and compaction density of lithium cobalt composite oxide at high voltage cannot be guaranteed; when t / (1+t)<0.15, the capacity and storage performance of lithium cobalt composite oxide at high voltage cannot be guaranteed; preferably, 0.15≤t / (1+t)≤0.28; more preferably, 0.18≤t / (1+t)≤0.24; in this case, the compaction density of the battery plate is>4.2g / cm 3 , storage performance is better, and the rest of the performance is balanced.

[0061] In some embodiments, 1-d1-d2-d3-d≤1-b1-b2-b3-b, and the doping amount of small particles is greater than that of large particles, thereby improving stability.

[0062] In some embodiments, d and b satisfy d≥b.

[0063] In some embodiments, both Q and Q′ include at least one of Mg, La, and Zr, and the element types of Q and Q′ may be consistent or inconsistent.

[0064] In some embodiments, the T is at least one of Mg, Al, Ti, and Zr.

[0065] In some embodiments, the E is at least one of F, P and C.

[0066] It is particularly noted that when the E element in the lithium cobalt oxide disclosed herein is F, the doping occupies the O position, lowering the overall Fermi level to match the reduction in the driving force for carbonate dehydrogenation; in the process of F replacing the O position, the Co element is reduced, which increases the energy barrier for electron conduction from the electrolyte, reduces interfacial side reactions, improves gas production, reduces Co dissolution, and improves storage.

[0067] In a second aspect, the present disclosure provides a method for preparing the lithium-ion battery positive electrode material as described in any one of the aforementioned embodiments, comprising: coating, mixing the large particle core, the small particle core and the coating layer raw materials and sintering them to obtain the lithium-ion battery positive electrode material.

[0068] In this disclosure, a large-particle core and a small-particle core are first prepared, and then both are coated simultaneously. This allows for element exchange between the large and small particles, improving their compatibility and capacity and cycle performance. Furthermore, under high voltage conditions, the material maintains high-voltage density and excellent gas production performance.

[0069] In some embodiments, the preparation of large-particle cores also includes sintering a precursor mixture containing lithium, nickel, cobalt, manganese, aluminum, and Q to obtain large-particle cores, wherein the ratio of the total molar amount of lithium to nickel, cobalt, manganese, aluminum and Q in the precursor mixture is m1+m2, wherein m1 is 1.04~1.12, m2=(N1*n1) / 3, wherein N1 is the molar amount of the Q element replacing the Co position, and n1 is the valence state of the Q element replacing the Co position, specifically m1 can be at least one of 1.04, 1.06, 1.08, 1.10, 1.12 or 1.04~1.12. During the first sintering, excessive addition of lithium will, on the one hand, result in a small amount of lithium loss during the sintering process, and on the other hand, it will be beneficial to the growth of particles, promote fuller particles, eliminate secondary grain boundaries between particles, make up for the loss of sintering lithium, improve material processing performance, compaction density, reduce defects, and lower the sintering temperature. Excessive addition of lithium is especially necessary for the preparation of large-grained single crystals and small-grained single crystals or single-crystal-like materials.

[0070] In some embodiments, in the large particle core preparation step, the sintering temperature is 950°C to 1100°C, specifically 950°C, 1000°C, 1050°C, 1100°C or any value between 950°C and 1100°C, and the time is 8h to 14h, specifically 8h, 9h, 10h, 11h, 12h or any value between 8h and 12h, and the sintering is carried out in an oxygen-containing atmosphere, such as a mixture of oxygen and nitrogen.

[0071] In some embodiments, the preparation of small particle cores is also included: a precursor mixture containing lithium, nickel, cobalt, manganese, aluminum, and Q' is sintered to obtain large particle cores, wherein the ratio of the total molar amount of lithium to nickel, cobalt, manganese, aluminum and Q' in the precursor mixture is m3+m4, wherein m3 is 1.02~1.09, m4=(N2*n2) / 3, wherein N2 is the molar amount of the Q' element replacing the Co position, and n2 is the valence state of the Q' element replacing the Co position, specifically m3 can be at least one of 1.02, 1.04, 1.06, 1.08, 1.09 or 1.02~1.09.

[0072] In some embodiments, in the small particle core preparation step, the sintering temperature is 850°C to 1025°C, specifically 850°C, 900°C, 950°C, 1000°C or any value between 850°C and 1025°C, and the time is 8h to 14h, specifically 8h, 9h, 10h, 11h, 12h or any value between 8h and 12h, and the sintering is carried out in an oxygen-containing atmosphere.

[0073] In some embodiments, in the coating step, the sintering temperature is 700°C to 1000°C, specifically 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C or any value between 700°C and 1000°C, and the time is 7h to 13h, specifically 7h, 8h, 9h, 10h, 11h, 12h, 13h or any value between 7h and 13h, and the sintering is carried out in an oxygen-containing atmosphere.

[0074] In this embodiment, the large particle core has a relatively high sintering temperature due to its large size. In the coating step, only the coating layer components need to be coated on the particle surface, so the sintering temperature can be slightly lower.

[0075] In some embodiments, the Q-containing compound and the Q′-containing compound used in the steps of preparing the large particle core and the small particle core are both micro-nano-scale particles. The use of small particles is conducive to the uniform dispersion of elements.

[0076] In some embodiments, the Q-containing compound used in the large particle core preparation step is at least one of a Q-containing oxide, hydroxide, and carbonate.

[0077] In some embodiments, the Q′-containing compound used in the small particle core preparation step is at least one of a Q′-containing oxide, a hydroxide, and a carbonate.

[0078] In some embodiments, the coating layer raw material includes at least two of the oxide of T, the hydroxide of T, the fluoride of T, the phosphide of T, the oxide of E, the hydroxide of E, the fluoride of E and the phosphide of E.

[0079] In a third aspect, the present disclosure provides a lithium-ion battery positive electrode, comprising the lithium-ion battery positive electrode material described in any one of the aforementioned embodiments or the lithium-ion battery positive electrode material obtained by the method described in any one of the aforementioned embodiments.

[0080] In a fourth aspect, the present disclosure provides a lithium-ion battery positive electrode, comprising the lithium-ion battery positive electrode described in the aforementioned embodiment.

[0081] In a fifth aspect, the present disclosure provides a lithium-ion battery comprising the lithium-ion battery positive electrode described in the aforementioned embodiment.

[0082] In a sixth aspect, the present disclosure provides an electrical device comprising the lithium-ion battery described in the aforementioned embodiment.

[0083] The features and performance of the present disclosure are further described in detail below with reference to the embodiments.

[0084] Example 1

[0085] This embodiment provides a lithium cobalt oxide, such as Figure 1 As shown, the preparation method is as follows:

[0086] S1. According to the chemical formula Li 1.006 Co 0.9367 Ni 0.01 Mn 0.0218 Al 0.027 Mg 0.0045 The molar ratio of O2 is 16μm, and Ni-Mn-Al doped cobalt tetroxide and magnesium oxide are weighed, and lithium carbonate is added so that the ratio of the molar amount of lithium to the total molar amount of the five elements of cobalt, nickel, manganese, aluminum and magnesium is 1.078. Place it in a ball mill with a rotation speed of 400r / min and a mass ratio of the ball material of 1.5:1. Mix the materials for 3 hours to obtain a mixed powder. Calcine the mixed powder at a calcination temperature of 1070℃ and a holding time of 12 hours. After natural cooling and crushing, crush and sieve to obtain a large-particle primary powder of lithium cobalt oxide with a D50 of 19.5μm.

[0087] S2. According to the chemical formula Li 1.006 Co 0.9327 Ni 0.01 Mn 0.0218 Al 0.03 Mg 0.0055 The molar ratio of O2 was weighed to be 4.5μm doped Ni-Mn-Al cobalt oxide and magnesium oxide, and lithium carbonate was added so that the ratio of the molar amount of lithium to the total molar amount of the five elements of cobalt, nickel, manganese, aluminum and magnesium was 1.048. It was placed in a ball mill with a rotation speed of 400r / min and a mass ratio of the ball material of 1.5:1. The materials were mixed for 3 hours to obtain a mixed powder. The mixed powder was calcined at a calcination temperature of 1025℃ and a calcination time of 10 hours. After natural cooling and sieving, a primary powder of lithium cobalt oxide small particles with a D50 of 5.3μm was obtained.

[0088] S3. The large-particle primary powder and the small-particle primary powder were placed in a molar ratio of 1:t=4:1, and the additives aluminum fluoride and titanium oxide (aluminum fluoride: titanium oxide=1:1, corresponding to x=0.005) were placed in a three-dimensional mixing device, placed in a ball mill, and rotated at 300r / min. The mass ratio of the balls and materials was 1.2:1. The materials were mixed for 2 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 950°C and kept warm for 8 hours. After natural cooling and crushing, it was pulverized to obtain (Li 1.006 Co 0.9367 Ni 0.01 Mn 0.0218 Al 0.027 Mg 0.0045 O2·0.25Li 1.006 Co 0.9327 Ni 0.01 Mn 0.0218 Al0.03 Mg 0.0055 O2)·0.005AlTiF3O2.

[0089] Example 2

[0090] This embodiment provides a lithium cobalt oxide, and the preparation method is as follows:

[0091] S1. According to the chemical formula Li 1.006 Co 0.9632 Ni 0.0017 Mn 0.0036 Al 0.027 Mg 0.0045 The molar ratio of O2 is 16μm, and Ni-Mn-Al doped cobalt tetroxide and magnesium oxide are weighed, and lithium carbonate is added so that the molar ratio of lithium to the total molar ratio of the five elements of cobalt, nickel, manganese, aluminum and magnesium is 1.076. Place it in a ball mill with a rotation speed of 400r / min and a mass ratio of the ball material of 1.5:1. Mix the materials for 3 hours to obtain a mixed powder. Calcine the mixed powder at a calcination temperature of 1065℃ and a holding time of 12 hours. After natural cooling and crushing, crush and sieve to obtain large-particle primary powder of lithium cobalt oxide.

[0092] S2. According to the chemical formula Li 1.006 Co 0.9495 Ni 0.005 Mn 0.01 Al 0.03 Mg 0.0055 The molar ratio of O2 is 4.5μm, and Ni-Mn-Al doped cobalt tetroxide and magnesium oxide are weighed, and lithium carbonate is added so that the ratio of the molar amount of lithium to the total molar amount of the five elements of cobalt, nickel, manganese, aluminum and magnesium is 1.044. Place it in a ball mill with a speed of 400r / min and a mass ratio of the ball material of 1.5:1. Mix the materials for 3 hours to obtain a mixed powder. Calcinate the mixed powder at a calcination temperature of 1020℃ and a calcination time of 10 hours. After natural cooling and sieving, obtain a primary powder of small particles of lithium cobalt oxide.

[0093] S3. The large-particle primary powder and the small-particle primary powder were placed in a molar ratio of 1:t=4:1, and the additives aluminum fluoride and titanium oxide (aluminum fluoride: titanium oxide=1:1, corresponding to x=0.005) were placed in a three-dimensional mixing device, placed in a ball mill, and rotated at 300r / min. The mass ratio of the balls and materials was 1.2:1. The materials were mixed for 2 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 940°C and kept warm for 8 hours. After natural cooling and crushing, it was pulverized to obtain (Li 1.006 Co 0.9632 Ni 0.0017 Mn 0.0036 Al 0.02 7Mg 0.0045O2·0.25Li 1.006 Co 0.9495 Ni 0.005 Mn 0.01 Al 0.03 Mg 0.0055 O2)·0.005AlTiF3O2.

[0094] Example 3

[0095] This embodiment provides a lithium cobalt oxide, and the preparation method is as follows:

[0096] S1. According to the chemical formula Li 1.006 Co 0.9632 Ni 0.0017 Mn 0.0036 Al 0.027 Mg 0.0045 The molar ratio of O2 is 16μm, and Ni-Mn-Al doped cobalt tetroxide and magnesium oxide are weighed, and lithium carbonate is added so that the molar ratio of lithium to the total molar ratio of cobalt, nickel, manganese, aluminum and magnesium is 1.076. Place it in a ball mill with a rotation speed of 400r / min and a mass ratio of balls of 1.5:1. Mix the materials for 3 hours to obtain a mixed powder. Calcine the mixed powder at a calcination temperature of 1060°C and a heat preservation time of 12 hours. After natural cooling and crushing, crush and sieve to obtain large-particle primary powder of lithium cobalt oxide.

[0097] S2. According to the chemical formula Li 1.006 Co 0.9592 Ni 0.0017 Mn 0.0036 Al 0.03 Mg 0.0055 The molar ratio of O2 is 4.5μm, and Ni-Mn-Al doped cobalt tetroxide and magnesium oxide are weighed, and lithium carbonate is added so that the ratio of the molar amount of lithium to the total molar amount of the five elements of cobalt, nickel, manganese, aluminum and magnesium is 1.041. Place it in a ball mill with a rotation speed of 400r / min and a mass ratio of the ball material of 1.5:1. Mix the materials for 3 hours to obtain a mixed powder. Calcinate the mixed powder at a calcination temperature of 1015℃ and a calcination time of 10 hours. After natural cooling and sieving, obtain a primary powder of small particles of lithium cobalt oxide.

[0098] S3. The large-particle primary powder and the small-particle primary powder were placed in a three-dimensional mixing device with a molar ratio of 1:t=4:1, and the additives aluminum fluoride and titanium oxide (aluminum fluoride: titanium oxide=1:1, corresponding to x=0.005) were placed in a ball mill at a speed of 300 r / min and a mass ratio of balls and materials of 1.2:1. The mixed powder was obtained by mixing for 2 hours, calcining the mixed powder at a temperature of 890°C and a holding time of 8 hours. After natural cooling and crushing, the powder was pulverized to obtain (Li 1.006 Co0.9632 Ni 0.0017 Mn 0.0036 Al 0.02 7Mg 0.0045 O2·0.25Li 1.006 Co 0.9592 Ni 0.0017 Mn 0.0036 Al 0.03 Mg 0.0055 O2)·0.005AlTiF3O2.

[0099] Example 4

[0100] This embodiment provides a lithium cobalt oxide, and the preparation method is as follows:

[0101] S1. According to the chemical formula Li 1.006 Co 0.9622 Ni 0.0017 Mn 0.0036 Al 0.027 Mg 0.0045 La 0.001 The molar ratio of O2 is 16μm, and Ni-Mn-Al doped cobalt tetroxide, magnesium oxide, and lanthanum oxide are weighed, and lithium carbonate is added so that the molar amount of lithium and the total molar amount of the five elements of cobalt, nickel, manganese, aluminum, magnesium and lanthanum is 1.073. Place it in a ball mill with a speed of 400r / min and a mass ratio of the ball material of 1.5:1. Mix the materials for 3 hours to obtain a mixed powder. Calcine the mixed powder at a calcination temperature of 1070°C and a heat preservation time of 12 hours. After natural cooling and crushing, crush and sieve to obtain large-particle primary powder of lithium cobalt oxide.

[0102] S2. According to the chemical formula Li 1.006 Co 0.9485 Ni 0.005 Mn 0.01 Al 0.03 Mg 0.0055 La 0.001 The molar ratio of O2 is 4.5μm, and Ni-Mn-Al doped cobalt tetroxide, magnesium oxide, and lanthanum oxide are weighed, and lithium carbonate is added so that the molar amount of lithium and the total molar amount of the five elements of cobalt, nickel, manganese, aluminum, magnesium and lanthanum is 1.044. Place it in a ball mill with a speed of 400r / min and a mass ratio of the ball material of 1.5:1. Mix the materials for 3 hours to obtain a mixed powder. Calcinate the mixed powder at a calcination temperature of 1025℃ and a calcination time of 10 hours. After natural cooling and sieving, obtain a primary powder of small particles of lithium cobaltate.

[0103] S3. The large-particle primary powder and the small-particle primary powder were placed in a molar ratio of 1:t=4:1, and the additives aluminum fluoride and titanium oxide (aluminum fluoride: titanium oxide=1:1, corresponding to x=0.005) were placed in a three-dimensional mixing device, placed in a ball mill, and rotated at 300r / min. The mass ratio of the balls and materials was 1.2:1. The materials were mixed for 2 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 950°C and kept warm for 8 hours. After natural cooling and crushing, it was pulverized to obtain (Li 1.006 Co 0.9622 Ni 0.0017 Mn 0.0036 Al 0.02 7Mg 0.0045 La 0.001 O2·0.25Li 1.006 Co 0.9485 Ni 0.005 Mn 0.01 Al 0.03 Mg 0.0055 La 0.001 O2)·0.005AlTiF3O2.

[0104] Example 5

[0105] This embodiment provides a lithium cobalt oxide, and the preparation method is as follows:

[0106] S1. According to the chemical formula Li 1.006 Co 0.9622 Ni 0.0017 Mn 0.0036 Al 0.027 Mg 0.0045 W 0.001 The molar ratio of O2 is 16μm, and Ni-Mn-Al doped cobalt tetroxide, magnesium oxide, and tungsten oxide are weighed, and lithium carbonate is added so that the molar amount of lithium and the total molar amount of the five elements of cobalt, nickel, manganese, aluminum, magnesium and tungsten are 1.068. Place it in a ball mill with a speed of 400r / min and a mass ratio of the ball material of 1.5:1. Mix the materials for 3 hours to obtain a mixed powder. Calcine the mixed powder at a calcination temperature of 1070℃ and a holding time of 12 hours. After natural cooling and crushing, crush and sieve to obtain large-particle primary powder of lithium cobalt oxide.

[0107] S2. According to the chemical formula Li 1.006 Co 0.9485 Ni 0.005 Mn 0.01 Al 0.03 Mg 0.0055 W 0.001The molar ratio of O2 is 4.5μm, and Ni-Mn-Al doped cobalt tetroxide, magnesium oxide, and tungsten oxide are weighed, and lithium carbonate is added so that the molar amount of lithium and the total molar amount of the five elements of cobalt, nickel, manganese, aluminum, magnesium and tungsten are 1.040. Place it in a ball mill with a speed of 400r / min and a mass ratio of the ball material of 1.5:1. Mix the materials for 3 hours to obtain a mixed powder. Calcinate the mixed powder at a calcination temperature of 1025℃ and a calcination time of 10 hours. After natural cooling and sieving, obtain a primary powder of small particles of lithium cobalt oxide.

[0108] S3. The large-particle primary powder and the small-particle primary powder were placed in a molar ratio of 1:t=4:1, and the additives aluminum fluoride and titanium oxide (aluminum fluoride: titanium oxide=1:1, corresponding to x=0.005) were placed in a three-dimensional mixing device, placed in a ball mill, and rotated at 300r / min. The mass ratio of the balls and materials was 1.2:1. The materials were mixed for 2 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 950°C and kept warm for 8 hours. After natural cooling and crushing, it was pulverized to obtain (Li 1.006 Co 0.9622 Ni 0.0017 Mn 0.0036 Al 0.02 7Mg 0.0045 W 0.001 O2·0.25Li 1.006 Co 0.9485 Ni 0.005 Mn 0.01 Al 0.03 Mg 0.0055 W 0.001 O2)·0.005AlTiF3O2.

[0109] Example 6

[0110] This embodiment provides a lithium cobalt oxide, and the preparation method is as follows:

[0111] S1. According to the chemical formula Li 1.006 Co 0.9622 Ni 0.0017 Mn 0.0036 Al 0.027 Mg 0.0045 Zr 0.001 The molar ratio of O2 is 16μm, and Ni-Mn-Al doped cobalt tetroxide, magnesium oxide, and zirconium oxide are weighed, and lithium carbonate is added so that the ratio of the molar amount of lithium to the total molar amount of the five elements of cobalt, nickel, manganese, aluminum, magnesium and zirconium is 1.073. It is placed in a ball mill with a rotation speed of 400r / min and a mass ratio of the ball material of 1.5:1. The materials are mixed for 3 hours to obtain a mixed powder. The mixed powder is calcined at a calcination temperature of 1070℃ and a heat preservation time of 12 hours. After natural cooling and crushing, it is crushed and sieved to obtain large-particle primary powder of lithium cobalt oxide.

[0112] S2. According to the chemical formula Li 1.006 Co 0.9485 Ni 0.005 Mn 0.01 Al 0.03 Mg 0.0055 Zr 0.001 The molar ratio of O2 is 4.5μm, and Ni-Mn-Al doped cobalt tetroxide, magnesium oxide, and zirconium oxide are weighed, and lithium carbonate is added so that the molar amount of lithium and the total molar amount of the five elements of cobalt, nickel, manganese, aluminum, magnesium and zirconium is 1.044. Place it in a ball mill with a speed of 400r / min and a mass ratio of the ball material of 1.5:1. Mix the materials for 3 hours to obtain a mixed powder. Calcinate the mixed powder at a calcination temperature of 1025℃ and a calcination time of 10 hours. After natural cooling and sieving, obtain a primary powder of small particles of lithium cobaltate.

[0113] S3. The large-particle primary powder and the small-particle primary powder were placed in a molar ratio of 1:t=4:1, and the additives aluminum fluoride and titanium oxide (aluminum fluoride: titanium oxide=1:1, corresponding to x=0.005) were placed in a three-dimensional mixing device, placed in a ball mill, and rotated at 300r / min. The mass ratio of the balls and materials was 1.2:1. The materials were mixed for 2 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 950°C and kept warm for 8 hours. After natural cooling and crushing, it was pulverized to obtain (Li 1.006 Co 0.9622 Ni 0.0017 Mn 0.0036 Al 0.02 7Mg 0.0045 Zr 0.001 O2·0.25Li 1.006 Co 0.9485 Ni 0.005 Mn 0.01 Al 0.03 Mg 0.0055 Zr 0.001 O2)·0.005AlTiF3O2.

[0114] Example 7

[0115] This embodiment provides a lithium cobalt oxide, and the preparation method is different from that of Example 2 only in that the molar ratio of the large-particle primary powder to the small-particle primary powder in step S3 is 1:t=4.3:0.7.

[0116] Example 8

[0117] This embodiment provides a lithium cobalt oxide, and the preparation method is different from that of Example 2 only in that the molar ratio of the large-particle primary powder to the small-particle primary powder in step S3 is 1:t=3.5:1.5.

[0118] Example 9

[0119] This embodiment provides a lithium cobalt oxide, and the preparation method is different from that of embodiment 2 only in that in step S3, the molar ratio of the coating addition to the primary powder of large and small particles is x=0.04.

[0120] Example 10

[0121] This embodiment provides a lithium cobalt oxide, and the preparation method is different from that of embodiment 2 only in that the molar ratio of the coating addition to the primary powder of large and small particles in step S3 is x=0.001.

[0122] Example 11

[0123] This embodiment provides a lithium cobalt oxide. The preparation method is different from that of embodiment 2 only in that the coating addition in step S3 is magnesium fluoride:titanium oxide = 1:1.

[0124] Example 12

[0125] This embodiment provides a lithium cobalt oxide. The preparation method is different from that of embodiment 2 only in that the coating addition in step S3 is magnesium fluoride:carbon=1:1.

[0126] Example 13

[0127] This embodiment provides a lithium cobalt oxide. The preparation method differs from that of embodiment 2 only in that, in step S1, lithium carbonate is added so that the ratio of the molar amount of lithium to the total molar amount of the five elements of cobalt, nickel, manganese, aluminum and magnesium is 1.072.

[0128] Example 14

[0129] This embodiment provides a lithium cobalt oxide. The preparation method differs from that of Example 2 only in that, in step S1, lithium carbonate is added so that the ratio of the molar amount of lithium to the total molar amount of the five elements of cobalt, nickel, manganese, aluminum, and magnesium is 1.083, and the particle size D50 is 19.5 μm.

[0130] Example 15

[0131] This embodiment provides a lithium cobalt oxide. The preparation method differs from that of Example 2 only in that, in step S1, the calcination temperature is 950°C and the holding time is 12 hours; in step S2, the calcination temperature is 850°C and the holding time is 12 hours; and in step S3, the calcination temperature is 700°C and the holding time is 12 hours.

[0132] Example 16

[0133] This embodiment provides a lithium cobalt oxide. The preparation method differs from that of Example 2 only in that, in step S1, the calcination temperature is 1100°C and the holding time is 8 hours; in step S2, the calcination temperature is 1000°C and the holding time is 12 hours; and in step S3, the calcination temperature is 1000°C and the holding time is 12 hours.

[0134] Comparative Example 1

[0135] This comparative example provides a lithium cobalt oxide, and the preparation method is as follows:

[0136] S1. According to the chemical formula Li 1.006 Co 0.928 Al 0.027 Mg 0.0045 Lithium carbonate, D50 16μm doped Al cobalt tetroxide, and magnesium oxide were weighed in a ball mill with a molar ratio of 1.5:1. The speed was 400r / min and the mass ratio of the balls was 1.5:1. The materials were mixed for 3 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 1070°C and kept warm for 12 hours. After natural cooling and crushing, it was crushed and sieved to obtain a large-particle primary powder of lithium cobalt oxide.

[0137] S2. According to the chemical formula Li 1.006 Co 0.9645 Al 0.03 Mg 0.0055 Lithium carbonate, D50 4.5μm doped Al cobalt tetroxide, and magnesium oxide were weighed in a ball mill with a molar ratio of 1.5:1. The mixture was mixed for 3 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 1025°C for 10 hours. After natural cooling and sieving, a small particle of lithium cobalt oxide was obtained as a primary powder.

[0138] S3. The large-particle primary powder and the small-particle primary powder were placed in a molar ratio of 1:t=4:1, and the additives aluminum fluoride and titanium oxide (aluminum fluoride: titanium oxide=1:1, corresponding to x=0.005) were placed in a three-dimensional mixing device, placed in a ball mill, and rotated at 300r / min. The mass ratio of the balls and materials was 1.2:1. The materials were mixed for 2 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 950°C and kept warm for 8 hours. After natural cooling and crushing, it was pulverized to obtain (Li 1.006 Co 0.928 Al 0.027 Mg 0.0045 O2·0.25Li 1.006 Co 0.9645 Al 0.03 Mg 0.0055 O2)·0.005AlTiF3O2.

[0139] Comparative Example 2

[0140] This comparative example provides a lithium cobalt oxide, and the preparation method is as follows:

[0141] S1. According to the chemical formula Li 1.006 Co 0.9668 Ni 0.0017 Al 0.027 Mg 0.0045 Lithium carbonate, D50 16μm doped Ni-Al cobalt tetroxide, and magnesium oxide were weighed in a ball mill at a molar ratio of 1.5:1. The speed was 400r / min and the mass ratio of the balls was 1.5:1. The materials were mixed for 3 hours to obtain a mixed powder. The mixed powder was calcined at a calcination temperature of 1065°C and a heat preservation time of 12 hours. After natural cooling and crushing, the powder was crushed and sieved to obtain a large-particle primary powder of lithium cobalt oxide.

[0142] S2. According to the chemical formula Li 1.006 Co 0.9595 Ni 0.005 Al 0.03 Mg 0.0055 Lithium carbonate, D50 4.5μm doped Ni-Al cobalt tetroxide, and magnesium oxide were weighed in a ball mill with a molar ratio of 1.5:1. The mixture was mixed for 3 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 1020°C for 10 hours. After natural cooling and sieving, a small particle of lithium cobalt oxide was obtained as a primary powder.

[0143] S3. The large-particle primary powder and the small-particle primary powder were placed in a molar ratio of 1:t=4:1, and the additives aluminum fluoride and titanium oxide (aluminum fluoride: titanium oxide=1:1, corresponding to x=0.005) were placed in a three-dimensional mixing device, placed in a ball mill, and rotated at 300r / min. The mass ratio of the balls and materials was 1.2:1. The materials were mixed for 2 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 940°C and kept warm for 8 hours. After natural cooling and crushing, it was pulverized to obtain (Li 1.006 Co 0.9668 Ni 0.0017 Al 0.027 Mg 0.004 5O2·0.25Li 1.006 Co 0.9595 Ni 0.005 Al 0.03 Mg 0.0055 O2)·0.005AlTiF3O2.

[0144] Comparative Example 3

[0145] This comparative example provides a lithium cobalt oxide, and the preparation method is as follows:

[0146] S1. According to the chemical formula Li 1.006 Co 0.9649 Mn 0.0036 Al 0.027 Mg 0.0045 Lithium carbonate, D50 16μm doped Mn-Al cobalt tetroxide, and magnesium oxide were weighed in a ball mill with a molar ratio of O2, and the speed was 400r / min. The mass ratio of the balls was 1.5:1. The materials were mixed for 3 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 1060℃ and the insulation time was 12 hours. After natural cooling and crushing, it was crushed and sieved to obtain a large-particle primary powder of lithium cobalt oxide.

[0147] S2. According to the chemical formula Li 1.006 Co 0.9545 Mn 0.01 Al 0.03 Mg 0.0055 Lithium carbonate, D50 of 4.5μm doped Mn-Al cobalt tetroxide, and magnesium oxide were weighed in a ball mill with a molar ratio of 1.5:1. The mixture was mixed for 3 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 1015°C for 10 hours. After natural cooling and sieving, a small particle of lithium cobalt oxide was obtained as a primary powder.

[0148] S3. The large-particle primary powder and the small-particle primary powder were placed in a three-dimensional mixing device with a molar ratio of 1:t=4:1, and the additives aluminum fluoride and titanium oxide (aluminum fluoride: titanium oxide=1:1, corresponding to x=0.005) were placed in a ball mill at a speed of 300 r / min and a mass ratio of balls and materials of 1.2:1. The mixed powder was obtained by mixing for 2 hours, calcining the mixed powder at a temperature of 890°C and a holding time of 8 hours. After natural cooling and crushing, the powder was pulverized to obtain (Li 1.006 Co 0.9649 Mn 0.0036 Al 0.027 Mg 0.004 5O2·0.25Li 1.006 Co 0.9545 Mn 0.01 Al 0.03 Mg 0.0055 O2)·0.005AlTiF3O2.

[0149] Comparative Example 4

[0150] This comparative example provides a lithium cobalt oxide, and the preparation method is as follows:

[0151] S1. According to the chemical formula Li 1.006 Co 0.9675 Al 0.027 Mg0.0045 La 0.001 Lithium carbonate, D50 16μm doped Al cobalt tetroxide, magnesium oxide, and lanthanum oxide are weighed in a ball mill with a molar ratio of O2, a rotation speed of 400r / min, a mass ratio of the ball material of 1.5:1, and mixed for 3 hours to obtain a mixed powder. The mixed powder is calcined at a calcination temperature of 1070℃ and a holding time of 12 hours. After natural cooling and crushing, it is crushed and sieved to obtain a large-particle primary powder of lithium cobalt oxide.

[0152] S2. According to the chemical formula Li 1.006 Co 0.9635 Al 0.03 Mg 0.0055 La 0.001 Lithium carbonate, D50 of 4.5μm doped Al cobalt tetroxide, magnesium oxide, and lanthanum oxide were weighed in a ball mill with a molar ratio of 1.5:1. The mixture was mixed for 3 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 1025°C and a calcination time of 10 hours. After natural cooling and sieving, a small particle of lithium cobalt oxide was obtained as a primary powder.

[0153] S3. The large-particle primary powder and the small-particle primary powder were placed in a molar ratio of 1:t=4:1, and the additives aluminum fluoride and titanium oxide (aluminum fluoride: titanium oxide=1:1, corresponding to x=0.005) were placed in a three-dimensional mixing device, placed in a ball mill, and rotated at 300r / min. The mass ratio of the balls and materials was 1.2:1. The materials were mixed for 2 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 950°C and kept warm for 8 hours. After natural cooling and crushing, it was pulverized to obtain (Li 1.006 Co 0.9675 Al 0.027 Mg 0.0045 La 0.00 1O2·0.25Li 1.006 Co 0.9635 Al 0.03 Mg 0.0055 La 0.001 O2)·0.005AlTiF3O2.

[0154] Comparative Example 5

[0155] This comparative example provides a lithium cobalt oxide, and the preparation method is as follows:

[0156] S1. According to the chemical formula Li 1.006 Co 0.9675 Al 0.027 Mg 0.0045 W 0.001Lithium carbonate, D50 16μm doped Al cobalt tetroxide, magnesium oxide, and tungsten oxide were weighed in a ball mill with a rotation speed of 400r / min and a mass ratio of balls and materials of 1.5:1. The materials were mixed for 3 hours to obtain a mixed powder. The mixed powder was calcined at a calcination temperature of 1070℃ and a holding time of 12 hours. After natural cooling and crushing, the powder was crushed and sieved to obtain a large-particle primary powder of lithium cobalt oxide.

[0157] S2. According to the chemical formula Li 1.006 Co 0.9635 Al 0.03 Mg 0.0055 W 0.001 Lithium carbonate, D50 4.5μm doped Al cobalt tetroxide, magnesium oxide, and tungsten oxide were weighed in a ball mill with a molar ratio of O2. The speed was 400r / min and the mass ratio of the balls was 1.5:1. The materials were mixed for 3 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 1025°C and a calcination time of 10 hours. After natural cooling and sieving, a primary powder of small particles of lithium cobalt oxide was obtained.

[0158] S3. The large-particle primary powder and the small-particle primary powder were placed in a molar ratio of 1:t=4:1, and the additives aluminum fluoride and titanium oxide (aluminum fluoride: titanium oxide=1:1, corresponding to x=0.005) were placed in a three-dimensional mixing device, placed in a ball mill, and rotated at 300r / min. The mass ratio of the balls and materials was 1.2:1. The materials were mixed for 2 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 950°C and kept warm for 8 hours. After natural cooling and crushing, it was pulverized to obtain (Li 1.006 Co 0.9675 Al 0.027 Mg 0.0045 W 0.001 O2·0.25Li 1.006 Co 0.9635 Al 0.03 Mg 0.0055 W 0.001 O2)0.005AlTiF3O2.

[0159] Comparative Example 6

[0160] This comparative example provides a lithium cobalt oxide, and the preparation method is as follows:

[0161] S1. According to the chemical formula Li 1.006 Co 0.9675 Al 0.027 Mg 0.0045 Zr 0.001Lithium carbonate, D50 16μm doped Al cobalt tetroxide, magnesium oxide, and zirconium oxide are weighed in a ball mill with a molar ratio of O2, a rotation speed of 400r / min, a mass ratio of the ball material of 1.5:1, and mixed for 3 hours to obtain a mixed powder. The mixed powder is calcined at a calcination temperature of 1070℃ and a holding time of 12 hours. After natural cooling and crushing, it is crushed and sieved to obtain a large-particle primary powder of lithium cobalt oxide.

[0162] S2. According to the chemical formula Li 1.006 Co 0.9635 Al 0.03 Mg 0.0055 Zr 0.001 Lithium carbonate, D50 of 4.5μm doped Al cobalt tetroxide, magnesium oxide, and zirconium oxide are weighed in a ball mill with a molar ratio of 1.5:1. The mixture is mixed for 3 hours to obtain a mixed powder. The mixed powder is calcined at a temperature of 1025°C and a calcination time of 10 hours. After natural cooling and sieving, a small particle of lithium cobalt oxide is obtained as a primary powder.

[0163] S3. The large-particle primary powder and the small-particle primary powder were placed in a molar ratio of 1:t=4:1, and the additives aluminum fluoride and titanium oxide (aluminum fluoride: titanium oxide=1:1, corresponding to x=0.005) were placed in a three-dimensional mixing device, placed in a ball mill, and rotated at 300r / min. The mass ratio of the balls and materials was 1.2:1. The materials were mixed for 2 hours to obtain a mixed powder. The mixed powder was calcined at a temperature of 950°C and kept warm for 8 hours. After natural cooling and crushing, it was pulverized to obtain (Li 1.006 Co 0.9675 Al 0.027 Mg 0.0045 Zr 0.001 O2·0.25Li 1.006 Co 0.9635 Al 0.03 Mg 0.0055 Zr 0.001 O2)0.005AlTiF3O2.

[0164] Comparative Example 7

[0165] This comparative example provides a lithium cobalt oxide, which is prepared by a method substantially the same as that of Example 2, except that a large-particle primary powder, an additive of aluminum fluoride and titanium oxide (aluminum fluoride: titanium oxide = 1:1, corresponding to x = 0.005) are placed in a three-dimensional mixing device, which is then placed in a ball mill at a rotation speed of 300 r / min and a mass ratio of balls to materials of 1.2:1. The materials are mixed for 2 hours to obtain a mixed powder, which is then calcined at a temperature of 950° C. for 8 hours, and then naturally cooled and crushed to obtain a large-particle secondary product (Li 1.006 Co0.9632 Ni 0.0017 Mn 0.0036 Al 0.027 Mg 0.0045 O2·0.005AlTi F3O2.

[0166] Small particle primary powder, additives aluminum fluoride, titanium oxide (aluminum fluoride: titanium oxide = 1:1, corresponding to x = 0.005) are placed in a three-dimensional mixing device, placed in a ball milling device, the speed is 300r / min, the mass ratio of the ball material is 1.2:1, mixed for 2 hours to obtain a mixed powder, calcined the mixed powder, the calcination temperature is 950℃, the heat preservation time is 8 hours, and after natural cooling and crushing, crushed to obtain a small particle secondary product (0.25Li 1.006 Co 0.9495 Ni 0.005 Mn 0.01 Al 0.03 Mg 0.0055 O2)·0.005AlTiF3O2. )

[0167] The large and small particles are calcined separately, and the large particle secondary product and the small particle secondary product are mixed in a molar ratio of 1:t=4:1. 1.006 Co 0.9632 Ni 0.0017 Mn 0.0036 Al 0.027 Mg 0.0045 O2·0.25Li 1.006 Co 0.9495 Ni 0.005 Mn 0.01 Al 0.03 Mg 0.0055 O2)·0.005AlTiF3O2.

[0168] Comparative Example 8

[0169] This comparative example provides a lithium cobalt oxide, which is prepared using a method substantially the same as that of Example 13, except that, in step S1, lithium carbonate is added so that the ratio of the molar amount of lithium to the total molar amount of the five elements of cobalt, nickel, manganese, aluminum, and magnesium is 1.063.

[0170] Comparative Example 9

[0171] This comparative example provides a lithium cobalt oxide that is not doped with nickel and manganese, using a method substantially the same as that of Example 14, except that, in step S1, lithium carbonate is added so that the ratio of the molar amount of lithium to the total molar amount of the five elements of cobalt, nickel, manganese, aluminum and magnesium is 1.075, and the particle size is 19.5 μm.

[0172] Comparative Example 10

[0173] This comparative example provides a lithium cobalt oxide, which is prepared using a method substantially the same as that of Example 2, except that in step S1 , the calcination temperature is 850° C. and the holding time is 12 hours.

[0174] Comparative Example 11

[0175] This comparative example provides a lithium cobalt oxide, which is prepared using a method substantially the same as that of Example 2, except that in step S1, the calcination temperature is 1200° C. and the holding time is 12 hours.

[0176] Performance Testing

[0177] The lithium cobalt oxides obtained in the above examples and comparative examples are as follows:

[0178] The lithium cobalt oxide prepared in the examples or comparative examples was used as the positive electrode material to prepare a lithium ion battery: lithium cobalt oxide, SP (conductive agent), and PVDF (binder) were mixed in a mass ratio of 92:4:4, NMP (N-methylpyrrolidone) was added, and the mixture was stirred to form a slurry, which was then coated on aluminum foil and dried at 80°C to prepare a positive electrode sheet.

[0179] Graphite, SP (conductive agent), binder, and dispersant were mixed in a mass ratio of 96.5:1.5:1.5:1.5, and a solvent (H2O) was added. The mixture was stirred to form a slurry, which was then coated on aluminum foil and dried at 80°C to form a negative electrode sheet.

[0180] The above-mentioned positive electrode sheet, negative electrode, electrolyte and separator are used as raw materials to assemble into a soft-pack battery.

[0181] Capacity testing: Four parallel samples of the prepared soft-pack batteries were formed and divided into different capacities. At room temperature (25°C), they were charged at a constant current rate of 0.2C to a voltage of V1. They were further charged at a constant voltage of V1 until the current dropped below 0.05C, reaching the V1 full charge state. The discharge capacity was then calculated by discharging the battery at a constant current rate of 0.2C to V2. The discharge capacity in grams at a 0.2C rate was calculated using the following formula: Discharge capacity in grams = discharge capacity / mass of the positive electrode material.

[0182] The test results of each embodiment and comparative example are shown in Table 1.

[0183] Table 1

[0184]

[0185]

[0186] From the comparison of the samples of Examples 1 to 3 in Table 1 and the samples of Comparative Examples 1 to 3, it can be seen that the capacity of the samples doped with nickel-manganese is significantly higher than that of the undoped samples, indicating that doping with nickel-manganese has a capacity-enhancing effect. The reason is that the nickel element plays an additional capacity-enhancing effect. As the content of small-particle nickel and manganese increases, the discharge capacity gradually increases. From the comparison of the samples of Examples 4 to 5 and the samples of Example 2, it can be seen that doping with lanthanum and tungsten has a capacity-enhancing effect. From the comparison of Example 2 and Examples 7 to 8, it can be seen that increasing the capacity of small particles increases, decreasing the proportion of small particles decreases, increasing the proportion of small particles, increasing the overall BET, shortening the lithium ion transmission channel, reducing the resistance during lithium ion deintercalation, and improving the capacity. From Example 2 and Examples 9 to 10, it can be seen that improving the quality of the coating increases the lithium ion migration impedance and reduces the capacity. From the comparison of Example 2 and Examples 11 to 12, it can be seen that improving the coating material results in a smaller change in capacity. From Examples 13 to 14 and Comparative Examples 8 to 9, it can be seen that nickel-manganese doping requires a higher lithium matching, and the nickel-manganese doping capacity is improved; nickel-manganese doping is easy to grow into agglomerates under low lithium matching ( Figure 6 ), grow into single crystal under higher lithium concentration ( Figure 5 ).

[0187] It can be seen from Examples 2, 15-16 and Comparative Examples 10-11 that the capacity decreases significantly when the temperature is too high.

[0188] The median particle size of the large particle core obtained in each embodiment and comparative example (except comparative examples 8 and 10) of the present application is about 19μm to 20μm, and the median particle size of the small particle core is about 4.5μm to 5.5μm, and the small particles in each embodiment and comparative example are all single crystal or quasi-single crystal structures. The large particles in Examples 1-16 and Comparative Examples 1-7 and 9 are all single crystal structures, and the large particles in Comparative Examples 8 and 10 are agglomerated structures. Although a large particle single crystal structure can be generated at high temperature in Comparative Example 11, the temperature is too high, the diameter of the large particles is larger, D50 reaches 25μm, and defects and excessive lithium loss will occur, thereby reducing material performance.

[0189] Figure 2 and Figure 3 The XRD patterns of Examples 1 and 2 show that there is no XRD peak corresponding to nickel-manganese doping (PDF#77-1370), indicating that nickel-manganese is in-situ doped into the crystal lattice to replace cobalt.

[0190] Figure 4 is the SEM image of the sample obtained in Example 2, Figure 5 and 6 SEM images of large particles in Example 13 and Comparative Example 8 are Figure 5 The medium and large particles are single crystal structures. Figure 6 The medium and large particles are agglomerated structures.

[0191] The resulting soft-pack batteries were tested at 45°C, 3.0-4.50V / 1.0C for 45°C cycling, 45°C storage performance, and 70°C storage gas generation. The results of the 50-day 70°C storage gas generation, 100-day 45°C storage capacity recovery, and 400-cycle retention tests for Examples 1, 2, 3, 4, 5, and 6 and Comparative Examples 1, 2, 3, 4, 5, 6, and 7 are shown in Table 2.

[0192] Table 2

[0193]

[0194] Comparison of Examples 1 to 3 with Comparative Examples 1 to 3 and 7 in Table 2 shows that at 45°C, 3.0-4.50V / 1.0C, nickel-manganese doping significantly improves cycling and 45°C storage, as well as gas production. The presence of nickel-manganese improves the band structure of cobalt, inhibits cobalt dissolution, and to a certain extent inhibits cobalt valence changes, indirectly inhibiting oxygen precipitation, thereby reducing interfacial side reactions, improving interface stability, and improving storage and gas production. Nickel-manganese doping generates a stable nickel-cobalt-manganese structure, inhibits phase change, and improves cycling. Comparative Example 7 uses a di-calcination + di-calcination process, resulting in poor matching between particle sizes, affecting lithium ion intercalation and deintercalation, and significant cycle attenuation.

[0195] Comparison of Examples 4 to 6 with Comparative Examples 4 to 6 shows that the increase of nickel-manganese doping improves the cyclic storage and gas production.

[0196] The results of the 50-day test of 70°C storage gas production, 100-day 45°C storage capacity recovery rate, and 400-week cycle retention rate for Examples 2, 7, 8, 9, 10, 11, and 12 and Comparative Examples 1 and 7 are shown in Table 3.

[0197] Table 3

[0198]

[0199] As shown in Table 3, when comparing Examples 2, 7, and 8 with Comparative Examples 1 and 7, it can be seen that increasing the amount of small particles improves storage, while circulation and gas production deteriorate; the transmission path of small-particle lithium is shorter, which is conducive to lithium ion deintercalation and storage improvement, but the increase in small particles increases BET, the interface and electrolyte contact area increases, and gas production deteriorates; increasing the proportion of large particles reduces BET, the interface and electrolyte contact area decreases, gas production and circulation are improved, the lithium ion transmission path increases, and storage deteriorates. When comparing Examples 2, 9, and 10 with Comparative Example 1 and Comparative Example 7, it can be seen that increasing the mass of the coating improves gas production and deteriorates storage; reducing the mass of the coating deteriorates circulation and gas production, reducing the coating material, and exacerbating interface side reactions. In Examples 2, 11, and 12 with Comparative Example 1 and Comparative Example 7, the surface mismatch after C coating leads to deteriorated circulation, inhibiting cobalt dissolution and oxygen precipitation, but improving gas production performance.

[0200] The results of the 50-day test of gas production at 70°C storage, the 100-day test of capacity recovery at 45°C storage, and the 400-cycle retention rate for Examples 2, 13-16, and Comparative Examples 8-11 are shown in Table 4.

[0201] Table 4

[0202]

[0203] As shown in Table 4, Examples 2, 13-14, and Comparative Examples 8-9 sintered to approximately the same large particle size. The nickel-manganese-doped samples required a higher lithium ratio and exhibited superior storage and gas production performance. Examples 15-16 and Comparative Examples 10-11 exhibited poor large particle crystallization at lower temperatures, resulting in poor storage and gas production. At higher temperatures, the particles appeared to pass through the screen, resulting in defects and poor storage and gas production performance.

[0204] Industrial Applicability

[0205] The present invention adjusts and optimizes the doping elements and doping amounts as well as the parameters of the preparation process to obtain single crystal or single crystal-like particles, reduce microcracks and reduce interface side reactions, and obtain lithium cobalt oxide suitable for the field of power batteries with good storage, circulation and gas production performance at a voltage of 4.50V or even higher, which has good industrial application prospects.

Claims

1. A lithium-ion battery positive electrode material, characterized in that Including large particles and small particles, The large particles include the general formula Li a Co 1-b1-b2-b3-b Ni b3 Mn b2 Al b1 Q b The large particle core of O2 is coated with a general formula T e E f O g The cladding layer; The small particles include the general formula Li c Co 1-d1-d2-d3-d Ni d3 Mn d2 Al d1 Q′ d The surface of the small particle core of O2 is coated with a general formula T e E f O g The cladding layer; The median particle size of the large particle core is 18 μm to 22 μm, the median particle size of the small particle core is 4 μm to 6 μm, the molar ratio of the small particles to the large particles is 0.1 to 0.5, the large particle core is a layered single crystal structure, and the small particle core is a layered single crystal or layered single crystal-like structure; Among them, 0.98≤a≤1.02, 0.002≤b≤0.05, 0.01≤b1≤0.035 ， 0.003≤b2≤0.025, 0.001≤b3≤0.015, 0.98≤c≤1.01, 0.001≤d≤0.06, 0.01≤d1≤0.05, 0.003≤d2≤0.03, 0.0015≤d3≤0.02, 0.8≤e≤3, 0≤f≤3, 1.5≤g≤5, b2>b3, d2>d3, Q and Q′ are each independently selected from at least one of Mg, Y, La, Zr, Cu, Na and W; T and E are each independently selected from at least one of Mg, B, La, St, W, Y, Zr, Ti, F, P and C; The general formula of lithium-ion battery cathode material is: (Li a Co 1-b1-b2-b3-b Ni b3 Mn b2 Al b1 Q b O2·tLi c Co 1-d1-d2-d3- d Ni d3 Mn d2 Al d1 Q′ d O2)·xT e E f O g , where 0.001≤x≤0.04, 0.12≤t≤0.45, and 0.12≤t / (1+t)≤0.

30.

2. The lithium-ion battery positive electrode material according to claim 1, characterized in that The median particle size of the large particle core is 19 μm to 20 μm, and the median particle size of the small particle core is 4.5 μm to 5.5 μm.

3. The lithium-ion battery positive electrode material according to claim 1 or 2, characterized in that 1-d1-d2-d3-d≤1-b1-b2-b3-b.

4. The lithium-ion battery positive electrode material according to claim 1, characterized in that d and b satisfy d ≥ b.

5. The lithium-ion battery cathode material according to claim 1, wherein Both Q and Q' include at least one of Mg, La and Zr.

6. The lithium-ion battery cathode material according to claim 1, characterized in that The T is at least one of Mg, Al, Ti and Zr.

7. The lithium-ion battery cathode material according to claim 1, wherein The E is at least one of F, P and C.

8. A method for preparing the positive electrode material for a lithium-ion battery according to any one of claims 1 to 7, characterized in that: The method comprises coating, wherein the large particle core, the small particle core and the coating layer raw materials are mixed and then sintered to obtain the positive electrode material of the lithium ion battery.

9. The method for preparing a positive electrode material for a lithium-ion battery according to claim 8, characterized in that: It also includes the preparation of large-particle cores: sintering a precursor mixture containing lithium, nickel, cobalt, manganese, aluminum, and Q to obtain large-particle cores, wherein the ratio of the total molar amount of lithium to nickel, cobalt, manganese, aluminum, and Q in the precursor mixture is m1+m2, wherein m1 is 1.04~1.12, and m2=(N1*n1) / 3, wherein N1 is the molar amount of the Q element replacing the Co position, and n1 is the valence state of the Q element replacing the Co position.

10. The method for preparing a positive electrode material for a lithium-ion battery according to claim 9, characterized in that: In the large particle core preparation step, the sintering temperature is 950° C. to 1100° C., the time is 8 h to 14 h, and the sintering is performed in an oxygen-containing atmosphere.

11. The method for preparing a positive electrode material for a lithium-ion battery according to any one of claims 8 to 10, characterized in that: It also includes the preparation of small particle cores: sintering a precursor mixture containing lithium, nickel, cobalt, manganese, aluminum, and Q' to obtain small particle cores, wherein the ratio of the total molar amount of lithium to nickel, cobalt, manganese, aluminum and Q' in the precursor mixture is m3+m4, wherein m3 is 1.02~1.09, m4=(N2*n2) / 3, wherein N2 is the molar amount of the Q' element replacing the Co position, and n2 is the valence state of the Q' element replacing the Co position.

12. The method for preparing a positive electrode material for a lithium-ion battery according to claim 11, characterized in that: In the small particle core preparation step, the sintering temperature is 850° C. to 1028° C., the sintering time is 8 hours to 14 hours, and the sintering is performed in an oxygen-containing atmosphere.

13. The method for preparing a positive electrode material for a lithium-ion battery according to claim 8, wherein: In the coating step, the sintering temperature is 700° C. to 1000° C., the sintering time is 7 hours to 13 hours, and the sintering is carried out in an oxygen-containing atmosphere.

14. The method for preparing a positive electrode material for a lithium-ion battery according to claim 11, wherein: The Q-containing compound and Q′-containing compound used in the steps of preparing the large particle core and the small particle core are both micro-nano-level particles.

15. The method for preparing a positive electrode material for a lithium-ion battery according to claim 14, characterized in that: The Q-containing compound used in the large particle core preparation step is at least one of a Q-containing oxide, hydroxide and carbonate.

16. The method for preparing a positive electrode material for a lithium-ion battery according to claim 15, characterized in that: The Q'-containing compound used in the small particle core preparation step is at least one of a Q'-containing oxide, hydroxide and carbonate.

17. The method for preparing a positive electrode material for a lithium-ion battery according to claim 8, characterized in that: The coating layer raw materials include at least two of T oxide, T hydroxide, T fluoride, T phosphide, E oxide, E hydroxide, E fluoride and E phosphide.

18. A positive electrode for a lithium ion battery, characterized in that: The invention comprises the lithium-ion battery positive electrode material according to any one of claims 1 to 7 or the lithium-ion battery positive electrode material obtained by the method according to any one of claims 8 to 17.

19. A lithium ion battery, characterized in that: The lithium-ion battery positive electrode according to claim 18 is included.

20. An electrical device, characterized in that: Including the lithium ion battery according to claim 19.

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