Positive electrode material, positive electrode plate, battery and electric device

Abstract

According to the positive electrode material, the battery and the power utilization device provided by the embodiment of the invention, in the positive electrode material, the differential capacity curve of the first ternary positive electrode material is controlled to have a characteristic peak at 4.1-4.2 V, so that more capacity is contributed, the energy density is favorably improved, and meanwhile, the energy density is improved. The differential capacity curve of the second ternary positive electrode material in the second active particles is controlled to have no characteristic peak at 4.1-4.2 V, so that the positive electrode material has better cycle performance and safety performance; according to the invention, the second ternary positive electrode material with high safety can be uniformly distributed in the first ternary positive electrode material system with poor safety, the first ternary positive electrode material with poor safety can be partitioned in a small range, and large-area thermal runaway is avoided, so that relatively high energy density and relatively good cycle performance and safety performance are considered.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a positive electrode material, a positive electrode sheet, a battery, and an electrical device. Background Technology

[0002] As a core carrier of new energy technologies, the improvement of energy density in lithium-ion batteries has become a key driving force for industrial development. In the cathode material system, high-nickel ternary material LiNi... x Co y M 1-x-y O Z (M=Mn, Al, x>0.6) Due to the significant increase in nickel content, the specific capacity (≥200 mAh / g) and energy density (>250 Wh / kg) can be improved, making it the current mainstream technology route.

[0003] However, the increased nickel content makes the drawbacks such as Li / Ni cation mixing, surface side reactions, and microcracks more prominent, resulting in a decrease in the cycle life and thermal stability of the battery. On the other hand, medium-nickel single crystal materials (such as single crystal NCM523 / 622) improve structural integrity and cycle life by eliminating grain boundaries, but their specific capacity is low (<180 mAh / g). Although the capacity can be increased by high-voltage charging, it is easy to cause lattice oxygen loss and intensified cation mixing, leading to uncontrolled surface side reactions and deterioration of thermal stability.

[0004] Therefore, there is an urgent need to develop a new material design strategy that can simultaneously improve cycle life and safety while maintaining the energy density of high-nickel systems. Summary of the Invention

[0005] This application provides a cathode material, a cathode sheet, a battery, and an electrical device, aiming to solve the problem that existing ternary cathode materials cannot effectively balance energy density and cycle performance.

[0006] To solve the above problems, this application provides the following technical solution: This application proposes a cathode material, comprising a first active particle and a second active particle; The first active particle includes a first ternary cathode material. In the first ternary cathode material, the molar percentage of nickel is greater than or equal to 80 mol% based on the total molar amount of transition metal elements other than lithium, and the differential capacity curve of the first ternary cathode material has a characteristic peak at 4.1~4.2V. The second active particle includes a second ternary cathode material. In the second ternary cathode material, the molar percentage of nickel is greater than or equal to 30 mol% and less than 80 mol% based on the total molar amount of transition metal elements other than lithium. Furthermore, the differential capacity curve of the second ternary cathode material does not have a characteristic peak at 4.1~4.2V.

[0007] The cathode material provided in this application includes a first active particle and a second active particle. The first active particle includes a first ternary cathode material as a high-nickel ternary cathode material, and the second active particle includes a second ternary cathode material as a medium-nickel ternary cathode material. By controlling the differential capacity curve of the first ternary cathode material to have a characteristic peak at 4.1~4.2V, it contributes more capacity, which is beneficial to improving energy density. At the same time, by controlling the differential capacity curve of the second ternary cathode material in the second active particle to have no characteristic peak at 4.1~4.2V, better cycle performance and safety performance are ensured. This allows the cathode material composed of the first and second active particles to uniformly distribute the high-safety second ternary cathode material within the low-safety first ternary cathode material system, achieving small-scale isolation of the low-safety first ternary cathode material and avoiding large-area thermal runaway, thus balancing high energy density and good cycle performance and safety performance. Therefore, the cathode material proposed in this application can effectively alleviate the problem that existing ternary cathode materials cannot effectively balance energy density and cycle performance, and has good application prospects.

[0008] Furthermore, in the cathode material, the first active particle is a polycrystalline particle, and the second active particle is a single-crystal particle.

[0009] Furthermore, in the aforementioned cathode material, the chemical formula of the first ternary cathode material is Li. 1+ a1 Ni x1 Co y1 Mn z1 O2, where x1+y1+z1=1, -0.1 <a1<0.2,0.8≤x1<1.0; The chemical formula of the second ternary cathode material is Li 1+a2 Ni x2 Co y2 Mn z2 O2, where x² + y² + z² = 1, -0.1 <a2<0.2,0.3≤x2<0.8。

[0010] Furthermore, in the cathode material, 0 < x1 - x2 < 0.7.

[0011] Furthermore, in the cathode material, the mass ratio of the first active particle to the second active particle is (45:55) to (95:5).

[0012] Furthermore, in the cathode material, the particle size D50 of the first active particle is 6~20 μm, and the particle size D50 of the second active particle is 1~6 μm; and / or The particle size D50 of the second active particle is 0.5~3 μm.

[0013] Furthermore, in the cathode material, the specific surface area of ​​the first active particle is 0.1~0.7 m² / g; and the specific surface area of ​​the second active particle is 0.5~2.0 m² / g.

[0014] Furthermore, in the cathode material, the first active particle further includes a first doping element and a first coating element, and / or the second active particle further includes a second doping element and a second coating element; The first doping element and the second doping element are independently selected from at least one of Al, B, Ba, Bi, Ca, Cr, Ce, Co, Er, Ga, Ge, Ho, K, La, Mg, Mo, Na, Nb, Pd, P, Si, Sb, Sr, Se, Ru, Rh, Ta, Te, Ti, W, V, Y, Zr and Zn; The first coating element and the second coating element are independently selected from at least one of Al, B, Ba, Bi, Ca, Cr, Ce, Co, Er, Ga, Ge, Ho, K, La, Mg, Mo, Na, Nb, Pd, P, Si, Sb, Sr, Se, Ru, Rh, Ta, Te, Ti, W, V, Y, Zr and Zn.

[0015] This application also proposes a positive electrode sheet, comprising a positive current collector and a positive active material layer disposed on the positive current collector, wherein the positive active material layer comprises the positive electrode material as described in any one of claims 1 to 7.

[0016] This application also proposes a battery comprising a positive electrode and a negative electrode; the positive electrode comprises a positive current collector and a positive active material layer disposed on the positive current collector, the positive active material layer comprising the positive electrode material as described above.

[0017] This application also proposes an electrical device, including a battery as described above, wherein the battery serves as the power supply for the electrical device. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a cathode material provided in an embodiment of this application; Figure 2 This is a 3kx scanning electron microscope image of the cathode material in Example 1 of this application; Figure 3 This is a 5kx scanning electron microscope image of the cathode material in Example 1; Figure 4 This is the energy dispersive X-ray spectrum of Mo element in the first active particle in Example 1; Figure 5 This is the Sr elemental energy dispersive X-ray spectrum of the second active particle in Example 1; Figure 6 This is the X-ray diffraction pattern of the cathode material in Example 1; Figure 7 This is a scanning electron microscope image of the positive electrode in Test Example 5; Figure 8 This is a comparison chart of the charge-discharge curves of the various materials in Example 1; Figure 9 This is the differential capacity curve of the cathode material in Example 1; Figure 10 This is the differential capacity curve of the first active particle and the second active particle in Example 1. Detailed Implementation

[0019] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] The applicant found that high nickel content is a key technological route to improve energy density and is also the main development trend of current ternary cathode materials. However, with the increase of nickel content, drawbacks such as Li / Ni cation mixing, surface side reactions, and microcracks become more prominent, leading to poorer cycle life and thermal stability. At the same time, the surface nickel content directly affects material performance; for example, it makes the material more susceptible to reaction with CO2 and moisture in the air, resulting in increased surface alkalinity, and the highly active Ni content during charging... 4+ Increased levels of these substances make the battery more prone to side reactions with the electrolyte, leading to poor storage and unstable battery performance.

[0021] To balance safety and cycling performance, medium-nickel single-crystal ternary materials (such as single-crystal NCM523 / 622) have become an important development direction. Among them, medium-nickel single-crystal structures have no grain boundaries, a dense particle structure, and high mechanical strength, reducing the contact between the electrolyte and the active material, thereby reducing the risk of gas generation and thermal runaway, suppressing phase transitions and structural collapse during cycling, and significantly extending lifespan. However, their specific capacity is relatively low (<180 mAh / g). Although the capacity can be increased by high-voltage charging (≥4.35V), it easily leads to lattice oxygen loss and intensified cation mixing, resulting in uncontrolled surface side reactions and deterioration of cycling performance and thermal stability.

[0022] To address the aforementioned issues, this application provides a cathode material comprising a first active particle and a second active particle. The first active particle comprises a first ternary cathode material, wherein, based on the total molar amount of transition metal elements other than lithium, the molar amount of nickel is greater than or equal to 80 mol%, and the differential capacity curve of the first ternary cathode material exhibits a characteristic peak at 4.1~4.2V. The second active particle comprises a second ternary cathode material, wherein, based on the total molar amount of transition metal elements other than lithium, the molar amount of nickel is greater than or equal to 30 mol% and less than 80 mol%, and the differential capacity curve of the second ternary cathode material does not exhibit a characteristic peak at 4.1~4.2V.

[0023] By charging and discharging the coin cell prepared from the positive electrode material with a small current (e.g., 0.1C), a "voltage-specific capacity" charge-discharge curve is obtained. The voltage and specific capacity data of the nth data point are subtracted from the voltage and specific capacity data of the (n+1)th data point to obtain dV and dQ data. The data dQ / dV is obtained by dividing dQ by dV. The dQ / dV curve is obtained by plotting dQ / dV on the ordinate and voltage on the abscissa.

[0024] In the charge-discharge curve, the voltage plateau has a high capacity, with a large capacity within a very small voltage fluctuation range. This is represented by a characteristic peak on the dQ / dV curve. Typically, each peak on the dQ / dV curve represents an electrochemical reaction. Since different materials have different reaction potentials, the peak positions and heights in the dQ / dV curves will vary.

[0025] The cathode material provided in this application includes a first active particle and a second active particle. The first active particle includes a first ternary cathode material as a high-nickel ternary cathode material, and the second active particle includes a second ternary cathode material as a medium-nickel ternary cathode material. By controlling the differential capacity curve of the first ternary cathode material to have a characteristic peak at 4.1~4.2V, it contributes more capacity and is beneficial to improving energy density. At the same time, by controlling the differential capacity curve of the second ternary cathode material in the second active particle to not have a characteristic peak at 4.1~4.2V, it ensures better cycle performance and safety performance. The cathode material composed of the first active particle and the second active particle can uniformly distribute the high-safety second ternary cathode material within the low-safety first ternary cathode material system, which can achieve small-scale isolation of the low-safety first ternary cathode material and avoid large-area thermal runaway, thereby achieving both high energy density and good cycle performance and safety performance.

[0026] Therefore, the cathode material provided in this application embodiment can effectively alleviate the problem that existing ternary cathode materials cannot effectively balance energy density and cycle performance, and has good application prospects.

[0027] In the cathode material provided by the embodiments of the present application, the above-mentioned first ternary cathode material and the above-mentioned second ternary cathode material can be lithium nickel cobalt manganese oxide and / or lithium nickel cobalt aluminate, that is, the above-mentioned cathode material can be composed of lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminate with a high nickel content and lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminate with a low nickel content blended together, which can give play to the high energy density advantage of the high-nickel ternary cathode material and the high thermal stability of the low-nickel ternary cathode material.

[0028] Optionally, in one embodiment, the above-mentioned first active particles are polycrystalline particles, and the second active particles are single-crystalline particles, that is, the first ternary cathode material is a high-nickel polycrystalline ternary cathode material, while the second ternary cathode material is a medium-nickel single-crystalline material.

[0029] In this embodiment, because there are no grain boundaries inside the particle structure of the medium-nickel single-crystalline material, the particle structure is dense, and the mechanical strength is high, it can reduce the contact between the electrolyte and the active material, thereby reducing the risk of gas generation and thermal runaway, inhibiting the phase change and structural collapse during the cycle, significantly extending the life, and its lower nickel content and higher cobalt content improve the intrinsic stability of the material. Through the polycrystalline and single-crystalline composite system, the contradiction between the thermal stability of the high-nickel material and the capacity of the medium-nickel material can be broken through, and a composite material with high energy density, high safety, and long life can be obtained.

[0030] Optionally, in one embodiment, the ternary cathode materials in each active particle in the cathode material can be detected by a scanning electron microscope, an energy dispersive X-ray spectrometer (EDS), and X-ray diffraction (XRD).

[0031] Optionally, in one embodiment, the chemical formula of the first ternary cathode material is Li 1+a1 Ni x1 Co y1 Mn z1 O2, the chemical formula of the second ternary cathode material is Li 1+a2 Ni x2 Co y2 Mn z2 O2, where x1 + y1 + z1 = 1, -0.1 < a1 < 0.2, 0.8 ≤ x1 < 1.0, x2 + y2 + z2 = 1, -0.1 < a2 < 0.2, 0.3 ≤ x2 < 0.8. This not only makes the first ternary cathode material have a higher energy density and the second ternary cathode material have higher thermal stability, but also can achieve the balance of high energy density and high thermal stability through the synergistic combination of the two components, thereby breaking through the contradiction between the thermal stability of the high-nickel material and the capacity of the medium-nickel material, and obtaining a composite material with high energy density, high safety, and long life. Optionally, in some implementations, 0 < x1 - x2 < 0.7, so that the differentiated design of the first ternary cathode material and the second ternary cathode material can effectively balance energy density and safety, achieving a balance between the two.

[0032] Optionally, in some embodiments, the mass ratio of the first active particle to the second active particle is (45:55) to (95:5). By precisely controlling the particle size matching of the two components, the stress concentration problem between particles is effectively reduced, thereby effectively improving the cycle performance.

[0033] Optionally, in some embodiments, the mass ratio of the first active particle in the cathode material is 60-95%, which can balance energy density and safety, ensuring high energy density while significantly reducing the risk of thermal runaway, and meeting the dual requirements of performance and safety for different application scenarios.

[0034] Optionally, in some embodiments, the particle size D50 of the first active particle is 6~20 μm, and the particle size D50 of the second active particle is 1~6 μm. When the particle size D50 of the first and second active particles is within the above-mentioned particle size range, the particle size distribution is reasonable, the material dynamics are better, the stress concentration problem between particles can be reduced, thereby effectively balancing compaction capacity, possessing stronger resistance to breakage, being easier to break during the cycle, and improving cycle performance and long-term storage performance.

[0035] In some embodiments, the particle size D50 of the first active particle can be one of 6μm, 7μm, 8μm, 10μm, 15μm, 20μm or any two of these values; the particle size D50 of the second active particle can be one of 1μm, 2μm, 3μm, 4μm, 5μm, 6μm or any two of these values.

[0036] Optionally, in some embodiments, the particle size D50 of the second active particles is 0.5~3 μm, which can better fill the gaps between the first active particles, reduce porosity, increase electrode compaction density, and directly increase volumetric energy density, thereby effectively alleviating the volume expansion stress of large particles during cycling, reducing electrode pulverization, and extending battery life. At the same time, it avoids the problem of aggravated side reactions (such as surface side reactions and electrolyte decomposition) caused by nano-sized particles, which leads to particle agglomeration and difficulty in slurry dispersion.

[0037] Optionally, the particle size of the second active particle can be one of 0.5 μm, 0.6 μm, 0.8 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm or any value between two of them.

[0038] Optionally, in one embodiment, the specific surface area of ​​the first active particle is 0.1~0.7 m² / g, and the specific surface area of ​​the second active particle is 0.5~2.0 m² / g. In this embodiment, controlling the specific surface area of ​​the first active particle to be between 0.1~0.7 m² / g and the specific surface area of ​​the second active particle to be between 0.5~2.0 m² / g allows the above-mentioned cathode material to exhibit excellent dispersibility and compaction density during electrode processing, significantly improving its ability to resist particle breakage, enhancing the material's structural stability, and making it compatible with existing battery manufacturing processes.

[0039] Optionally, the specific surface area of ​​the first active particle can be one or a range between any two of 0.1 m² / g, 0.2 m² / g, 0.3 m² / g, 0.4 m² / g, 0.5 m² / g, 0.6 m² / g, and 0.7 m² / g, and the specific surface area of ​​the second active particle can be one or a range between any two of 0.5 m² / g, 0.6 m² / g, 0.8 m² / g, 1.0 m² / g, 1.5 m² / g, and 2.0 m² / g.

[0040] Optionally, the particle size of the first active particles and the second active particles can be adjusted during the preparation process by adjusting the particle size of the hydroxide precursor, and the specific surface area of ​​the first active particles and the second active particles can be adjusted by adjusting the sintering temperature, crushing intensity, surface washing, and surface coating with different substances.

[0041] Optionally, in one embodiment, the first active particle further includes a first doping element and a first coating element, and the second active particle further includes a second doping element and a second coating element; wherein the first doping element and the second doping element are independently selected from at least one of Al, B, Ba, Bi, Ca, Cr, Ce, Co, Er, Ga, Ge, Ho, K, La, Mg, Mo, Na, Nb, Pd, P, Si, Sb, Sr, Se, Ru, Rh, Ta, Te, Ti, W, V, Y, Zr, and Zn; The first coating element and the second coating element are independently selected from at least one of Al, B, Ba, Bi, Ca, Cr, Ce, Co, Er, Ga, Ge, Ho, K, La, Mg, Mo, Na, Nb, Pd, P, Si, Sb, Sr, Se, Ru, Rh, Ta, Te, Ti, W, V, Y, Zr and Zn.

[0042] In this embodiment, the first and second active particles are coated or doped with the aforementioned elements, respectively. Coating covers the grain boundaries of polycrystalline particles and the surface of single-crystal particles, reducing electrolyte erosion, inhibiting transition metal dissolution, mitigating grain boundary cracking, and improving thermal stability. Doping strengthens grain boundary bonding and suppresses phase transitions. For example, Al and Mg doping can suppress the H2→H3 phase transition during charging and discharging, reducing volume expansion; Ti and Zr doping can enhance grain boundary mechanical strength; and Nb and Ta high-valence doping can reduce cation mixing and improve the lithium-ion diffusion coefficient.

[0043] The method for preparing the cathode material provided in this application includes steps 201 to 203: Step 201: Prepare nickel-cobalt-manganese hydroxides with different compositions and particle sizes using a co-precipitation method; Step 202: The obtained nickel-cobalt-manganese hydroxide is sintered with a lithium source to prepare a first ternary cathode material and a second ternary cathode material, respectively; Step 203: Place the first ternary cathode material and the second ternary cathode material into a mixing device according to a preset mass ratio, and mix them evenly in a dry environment to obtain the cathode material.

[0044] In the embodiments of this application, the cathode material as described above can be prepared through steps 201 to 203.

[0045] Optionally, by using a combination of polycrystalline and monocrystalline composite systems, elemental doping, surface coating and sintering processes, the contradiction between the thermal stability of high-nickel materials and the capacity of medium-nickel materials can be overcome, resulting in composite materials that combine high energy density, high safety and long life, with the exothermic peak temperature increased to ≥220℃.

[0046] Optionally, the preset mass ratio can be (45:55) to (95:5), which can reduce the stress concentration problem between particles and thus effectively improve the cycle performance of the material.

[0047] Optionally, the lithium source mentioned above includes one or more of anhydrous lithium hydroxide, lithium hydroxide monohydrate, lithium carbonate, and lithium nitrate.

[0048] Optionally, in one embodiment, during step 202 above, when the obtained nickel-cobalt-manganese hydroxide is sintered with a lithium source to prepare the first ternary cathode material and the second ternary cathode material, a first dopant and a second dopant are also added respectively. The first dopant and the second dopant independently include at least one of Al, B, Ba, Bi, Ca, Cr, Ce, Co, Er, Ga, Ge, Ho, K, La, Mg, Mo, Na, Nb, Pd, P, Si, Sb, Sr, Se, Ru, Rh, Ta, Te, Ti, W, V, Y, Zr and Zn.

[0049] Optionally, in one embodiment, during step 202 above, when the obtained nickel-cobalt-manganese hydroxide is sintered with a lithium source to prepare the first ternary cathode material and the second ternary cathode material, a first coating agent and a second coating agent are also added respectively. The first coating agent and the second coating agent independently include at least one of Al, B, Ba, Bi, Ca, Cr, Ce, Co, Er, Ga, Ge, Ho, K, La, Mg, Mo, Na, Nb, Pd, P, Si, Sb, Sr, Se, Ru, Rh, Ta, Te, Ti, W, V, Y, Zr and Zn.

[0050] Optionally, the sintering temperature during the preparation of the first ternary cathode material is 300~950℃. Sintering the first ternary cathode material at the above temperature not only ensures that the lithium source fully enters the interior of the material particles, avoiding excessive LiOH / Li2CO3 residue on the surface, which would lead to increased gas production in the battery, but also reduces lithium-nickel mixing, avoiding the formation of more inert rock salt phases and coarsening of the first ternary cathode material particles, thus preventing performance degradation.

[0051] In some embodiments, during the sintering process of preparing the first ternary cathode material, the sintering temperature can be one of 300°C, 350°C, 400°C, 500°C, 800°C, 950°C, or any value between two of them.

[0052] Optionally, the sintering temperature during the preparation of the second ternary cathode material is 300~1100℃. Sintering the second ternary cathode material at this temperature allows the lithium source to fully penetrate the material particles, avoiding excessive LiOH / Li2CO3 residue on the surface, which could lead to increased battery gas generation and the inability to achieve single crystallization. It also reduces lithium-nickel mixing, preventing the formation of excessive inert rock salt phases and thus performance degradation.

[0053] In some embodiments, during the sintering process for preparing the second ternary cathode material, the sintering temperature can be one of 300°C, 350°C, 400°C, 500°C, 600°C, 900°C, 1100°C, or any value between two of these.

[0054] This application also provides an electrode sheet, including a positive current collector and a positive active material layer disposed on the positive current collector, wherein the positive active material layer includes the positive electrode material as described above.

[0055] This application also provides a battery, including a positive electrode sheet; wherein the positive electrode sheet includes a positive current collector and a positive active material layer disposed on the positive current collector, and the positive active material layer includes the positive electrode material as described above.

[0056] In the battery provided in this application embodiment, the positive electrode sheet further includes a conductive agent and a binder; optionally, the conductive agent includes at least one of graphite, hard carbon, soft carbon, carbon nanotubes, graphene, porous carbon, superconducting carbon black (Super P), acetylene black, and furnace black; the binder includes at least one of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), silicone rubber, styrene-butadiene rubber (SBR), hydrogenated nitrile butadiene rubber (HNBR), boronized polyethylene glycol, cellulose, cellulose ester, cellulose ether, nitrocellulose, carboxyalkyl cellulose, cellulose salt, sodium carboxymethyl cellulose and cellulose salt derivatives, polyacrylic acid (PAA), polyamide (PAI), polyvinyl alcohol (PVA), polyethyleneimine (PEI), and polyimide (PI).

[0057] In some embodiments, the mass percentage of each component in the positive electrode active material layer is: 80-99 wt% positive electrode active material, 0.5-10 wt% conductive agent, and 0.5-10 wt% additives.

[0058] When the mass percentage of the positive electrode active material in the positive electrode active material layer is within the above range, the positive electrode sheet can have a high specific capacity, which can fully utilize the rate performance of the battery and meet the battery's fast charging and discharging requirements.

[0059] In some embodiments, the positive electrode active material layer further contains 0.1–30 wt% of a solid electrolyte, while the proportions of the remaining components remain unchanged. The solid electrolyte includes, but is not limited to, one or more of the following: NASICON (sodium fast ion conductor) type solid electrolyte, LISICON (lithium fast ion conductor) type solid electrolyte, garnet type solid electrolyte, perovskite type solid electrolyte, anti-perovskite type solid electrolyte, sulfide solid electrolyte, halide solid electrolyte, and polymer electrolyte. The polymer electrolyte includes polymers and lithium salts; polymers include, but are not limited to, PEO (ethylene oxide), PVDF (polyvinylidene fluoride), PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene), PMMA (polymethyl methacrylate), and PAN (polyacrylonitrile); lithium salts include, but are not limited to, LiPF6, LiTFSI, LiFSI, and LiDFOB.

[0060] In some embodiments, the positive current collector is selected from a metallic material that can conduct electrons. Preferably, the positive current collector includes one or more of aluminum, copper, nickel, tin, copper, and stainless steel. In a more preferred embodiment, the positive current collector is selected from aluminum foil.

[0061] In some embodiments, the positive electrode sheet is prepared by a wet process: the components used to prepare the positive electrode sheet, such as the positive electrode material, binder and any other components, are dispersed in a solvent such as N-methylpyrrolidone to form a positive electrode slurry; the positive electrode slurry is coated on both sides of a positive electrode current collector such as an aluminum foil; after baking, rolling, cutting and slitting, the positive electrode sheet can be obtained.

[0062] In some embodiments, the positive electrode sheet is prepared by fibrillation: the components used to prepare the positive electrode sheet, such as the positive electrode material, binder and any other components, are mixed, and shear force is applied to the mixed powder to fibrillate the binder to obtain a preform; the preform is extruded or rolled into a self-supporting film; the self-supporting film is loaded onto a current collector rolling between two rollers, and after processes such as rolling, cutting and slitting, the positive electrode sheet can be obtained.

[0063] The secondary battery provided in this embodiment of the invention also includes a negative electrode, a separator, and an electrolyte.

[0064] In some embodiments, the negative electrode sheet is a lithium metal sheet or a lithium alloy sheet, and its thickness is 0~100 μm. The lithium alloy Li-M can be an alloy formed by lithium metal with one or more of the following substances: gold, indium, magnesium, zinc, chromium, nickel, molybdenum, tungsten, vanadium, titanium, niobium, zirconium, cobalt, manganese, aluminum, copper, boron, silver, tin, silicon, carbon, and phosphorus, wherein the lithium metal content is 1~99% by mass.

[0065] In some embodiments, the negative electrode sheet includes a negative current collector and a negative active material layer coated on one or both surfaces of the negative current collector. The negative active material layer includes a negative active material, a conductive agent, a binder, and a thickener.

[0066] In one embodiment, the negative electrode active material includes, but is not limited to, one or more of lithium metal (Li) or lithium metal alloy (Li-M), artificial graphite, natural graphite, modified graphite, fast-charging graphite, soft carbon, hard carbon, fumed silicon carbide, ground silicon carbide, silicon suboxide, pre-lithiated silicon suboxide, and pre-magnesiated silicon suboxide; wherein, the lithium metal alloy (Li-M) can be an alloy formed by lithium metal and one or more of the following substances: gold, indium, magnesium, zinc, chromium, nickel, molybdenum, tungsten, vanadium, titanium, niobium, zirconium, cobalt, manganese, aluminum, copper, boron, silver, tin, silicon, carbon, and phosphorus, wherein the mass content of lithium metal is 1-99%.

[0067] In some embodiments, the negative electrode conductive agent includes one or more of Super-P (conductive carbon black), VGCF (vapor-grown carbon fiber), and CNT (carbon nanotube).

[0068] In some embodiments, the negative electrode binder includes one or more of PVDF (polyvinylidene fluoride), SBR (styrene-butadiene rubber), NBR (nitrile rubber), BR (polybutadiene rubber), CMC (sodium carboxymethyl cellulose), and PAA (polyacrylic acid).

[0069] In some embodiments, the thickener includes one or more of sodium alginate, sodium carboxymethyl cellulose, and carboxymethyl chitosan.

[0070] In some embodiments, the mass percentage of each component in the negative electrode active material layer is: 80-100 wt% negative electrode active material, 0-10 wt% conductive agent and 0-10 wt% binder.

[0071] The negative electrode current collector is selected from a metallic material that can conduct electrons. Preferably, the negative electrode current collector includes one or more of aluminum, nickel, tin, copper, and stainless steel. In a more preferred embodiment, the negative electrode current collector is selected from copper foil.

[0072] The negative electrode sheet can be prepared according to conventional methods in the art. For example, the negative electrode active material layer is typically formed by coating a negative electrode slurry, consisting of a negative electrode active material, a negative electrode conductive agent, a negative electrode binder, and any other components, onto a negative electrode current collector, followed by drying and cold pressing. The solvent can be an aqueous solvent, but is not limited to it.

[0073] The battery provided in this embodiment of the invention also includes a separator and an electrolyte.

[0074] The diaphragm includes a base membrane, which can be one or more of the following: PE diaphragm, PP diaphragm, non-woven fabric diaphragm, and PI diaphragm.

[0075] In some embodiments, the base film has a coating on at least one side; the coating comprises: an oxide solid electrolyte, an alkaline oxide, and a polymer adhesive; the oxide solid electrolyte and the alkaline oxide are dispersed in the polymer adhesive; the alkaline oxide comprises at least one of alumina and boehmite. The oxide solid electrolyte comprises at least one of NASICON-type solid electrolyte, garnet-type solid electrolyte, and perovskite-type solid electrolyte.

[0076] The electrolyte plays a role in conducting ions between the positive and negative electrode plates. The electrolyte can be liquid, gel, or completely solid.

[0077] Electrolytes include electrolytes, which include liquid electrolytes, semi-solid electrolytes, and all-solid electrolytes. Semi-solid electrolytes are obtained by mixing liquid electrolytes and solid electrolytes in any proportion.

[0078] Liquid electrolytes, semi-solid electrolytes, and all-solid electrolytes are all used in one or more of the following: pouch cells, cylindrical cells, or prismatic cells.

[0079] In some embodiments, the electrolyte may be selected from inorganic solid electrolytes (halide solid electrolytes, oxide solid electrolytes, sulfide solid electrolytes), polymer solid electrolytes, and composite solid electrolytes (inorganic filler + polymer matrix).

[0080] In some embodiments, the solid electrolyte includes, but is not limited to, one or more of the following: NASICON (sodium fast ion conductor) type solid electrolyte, LISICON (lithium fast ion conductor) type solid electrolyte, garnet type solid electrolyte, perovskite type solid electrolyte, anti-perovskite type solid electrolyte, sulfide solid electrolyte, halide solid electrolyte, and polymer electrolyte. Polymer electrolytes include polymers and lithium salts; polymers include, but are not limited to, PEO (ethylene oxide), PVDF (polyvinylidene fluoride), PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene), PMMA (polymethyl methacrylate), and PAN (polyacrylonitrile); lithium salts include, but are not limited to, LiPF6, LiTFSI, LiFSI, and LiDFOB.

[0081] In some embodiments, the electrolyte is a liquid electrolyte comprising an electrolyte salt and a solvent. The electrolyte salt is a lithium salt, and the solvent includes, but is not limited to, one or more of the following: ethylene carbonate, propylene carbonate, butene carbonate, fluoroethylene carbonate, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, diphenyl carbonate, fluoroethylene carbonate, and dimethyl glycol ether.

[0082] In some embodiments, the electrolyte is a gel electrolyte, comprising a polymer matrix, a plasticizing solvent, and a lithium salt.

[0083] In some embodiments, the electrolyte is an in-situ polymerized electrolyte, comprising polymer monomers, lithium salts, solvents, and initiators.

[0084] In some embodiments, the electrolyte is a eutectic electrolyte, comprising a small molecule polar matrix and a lithium salt; or an ionic liquid electrolyte, comprising an ionic liquid and a lithium salt.

[0085] In some embodiments, the lithium salts mentioned above include, but are not limited to, lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroantimonyate (LiSbF6), lithium bis(trifluoromethanesulfonate imide) (LiTFSI or LiN(SO2CF3)2), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(fluorosulfonyl)imide (LiFSI or LiN(SO2CF3)2), lithium perchlorate (LiClO4), lithium iodide (LiI), and lithium magnesium bis(fluorosulfonyl)imide (Li2Mg(N(SO2CF3)2)2).

[0086] In practical applications, the negative electrode, separator and positive electrode are stacked or wound in sequence, and then packaged to obtain a bare cell. After baking the bare cell, it is injected with electrolyte, formed, resealed and sorted to obtain the battery mentioned above.

[0087] In some implementations, a liquid cylindrical battery, a pouch battery, or a prismatic battery can be formed by stacking or winding negative electrode plates, positive electrode plates, a separator, and an electrolyte. In some implementations, a semi-solid cylindrical battery, a pouch battery, or a prismatic battery can be formed by stacking or winding negative electrode plates, positive electrode plates, and gel electrolyte. In some implementations, a semi-solid cylindrical battery, a pouch battery, or a prismatic battery can be formed by stacking or winding negative and positive electrode sheets, solid electrolyte, and 0.5-50% electrolyte additives. In some implementations, a solid cylindrical battery, a pouch battery, or a prismatic battery can be formed by stacking or winding negative electrode plates, positive electrode plates, and a solid electrolyte.

[0088] The present invention also proposes an electrical device, wherein the battery described above is included, and the battery serves as the power supply for the electrical device.

[0089] Batteries can be used as a power source for electrical devices or as energy storage units within electrical devices. Electrical devices can include, but are not limited to, mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc. Mobile devices can include, for example, mobile phones and laptops; electric vehicles can include, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc., but are not limited to these.

[0090] The above-described embodiment of the electrical device includes the aforementioned battery and achieves the same technical effect. To avoid repetition, it will not be described again here. For relevant details, please refer to the description of the battery embodiment.

[0091] To make the inventive objectives, technical solutions, and beneficial effects of this invention clearer, the invention is further described below with reference to embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0092] The present invention will be described in detail below through embodiments.

[0093] Test method: (1) First discharge specific capacity test: The positive electrode material is fabricated into a standard coin cell or pouch cell, and the counter electrode is set to lithium metal. At room temperature, a constant current / constant voltage charge / discharge system (such as a Battery Testing System) is used to perform charge / discharge cycles at a set current density. The test steps include: Charge to the set cutoff voltage of 4.3V at the set current density (0.1C); Discharge at the same current density (0.1C) until the set discharge cutoff voltage of 2.8V is reached; Record the specific capacity during the first discharge, in mAh / g.

[0094] (2) First-lap Coulomb efficiency test: At room temperature, using a constant current and constant voltage charge-discharge apparatus, the amount of electricity passing through the battery during the first charge and discharge cycle was measured. The test steps included: Charge to the set voltage and record the total amount of electricity charged (Q_charge); Discharge to the set cutoff voltage and record the total amount of charge discharged (Q_discharge); Calculate the Coulomb efficiency for the first cycle: Coulomb efficiency = (Q_discharge / Q_charge) × 100%.

[0095] (3) 100-week capacity retention test: At room temperature, under the same current density and voltage window, the positive electrode active material was subjected to 100 charge-discharge cycles. The test procedures included: The battery was subjected to 100 charge-discharge cycles, and the discharge capacity was recorded periodically each time. Calculate the capacity retention rate after 100 cycles: Capacity retention rate = (Discharge capacity at week 100 / Initial discharge capacity) × 100% The cathode materials obtained in the examples were assembled into liquid batteries, semi-solid batteries, and solid batteries, and charge-discharge tests and cycle tests were performed. Unless otherwise specified, the techniques or conditions described in the literature in this field or the product instructions were followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0096] Example 1 (1) Preparation of the first active particle A solution of nickel sulfate, cobalt sulfate, and manganese sulfate was prepared and pumped into a container at a certain rate. Under nitrogen protection, ammonia water and sodium hydroxide solution were continuously added to the reactor to carry out the reaction. After the target particle size was reached, the reaction was terminated, yielding a spherical hydroxide precursor with a particle size distribution D50 of 13.3 micrometers and a molecular formula of Ni. 0.94 Co 0.04Mn 0.02 (OH)2; With a molar ratio of Li / Me = 1.03, the hydroxide precursor was sintered with lithium hydroxide monohydrate and zirconium oxide (ZrO2, Zr doping amount 2000 ppm) at 720℃ for 10 h in an oxygen atmosphere to obtain a first-burned product. The first-burned product was crushed, washed with water, and dried. The dried product was then sintered with ammonium molybdate ((NH4)2MoO4, Mo coating amount 1000 ppm) at 500℃ for 6 h in an oxygen atmosphere. After passing through a 200-mesh sieve, the first active particles in a polycrystalline state were obtained.

[0097] (2) Preparation of the second active particles A solution of nickel sulfate, cobalt sulfate, and manganese sulfate was prepared and pumped into a container at a certain rate. Under nitrogen protection, the solution was continuously added to the reactor along with ammonia and sodium hydroxide solution. The reaction was terminated once the target particle size was reached, yielding a spherical hydroxide precursor with a particle size distribution D50 of 3.3 micrometers and the molecular formula Ni. 0.6 Co 0.1 Mn 0.3 (OH)2; With a molar ratio of Li / Me = 1.04, the hydroxide precursor, lithium carbonate as a lithium source, and strontium hydroxide (Sr(OH)2, Sr doping amount 1000 ppm) as a dopant were sintered at 950 °C for 10 h in an oxygen atmosphere to obtain a first-burned product. The first-burned product was crushed, washed with water, and dried. The dried product was then sintered with strontium carbonate (SrCO3, Sr coating amount 500 ppm) at 400 °C for 8 h in an oxygen atmosphere. After passing through a 325-mesh sieve, the second active particles in a single-crystal state were obtained.

[0098] (3) Preparation of cathode materials The first and second active particles prepared above are weighed and mixed evenly at a mass ratio of 80:20 to obtain a mixed cathode material.

[0099] Examples 2-4 The difference between Examples 2-4 and Example 1 is that, in step (3), the mass ratio of the first active particle and the second active particle is adjusted to 90:10, 45:55 and 95:5 respectively.

[0100] Example 5 The difference between Example 5 and Example 1 is that in step (1), the particle size of the precursor is adjusted to 6.1 μm; and in step (2), the sintering temperature is adjusted to 930 °C.

[0101] Example 6 The difference between Example 6 and Example 1 is that in step (1), the particle size of the precursor is adjusted to 20.2 μm; and in step (2), the sintering temperature is adjusted to 1000 °C.

[0102] Test Example 1 Scanning electron microscopy (SEM) was performed on the cathode materials in Examples 1-6 to determine the distribution D50 and specific surface area of ​​each material. The results are shown in Table 1. The SEM results for the cathode material in Example 1 are as follows: Figure 2 , 3 As shown, there are two particle sizes in the prepared cathode material: the large-particle first ternary cathode material has a D50 of 12.8 μm; the small-particle second ternary cathode material has a D50 of 3.5 μm, and its primary particle size is 2.2 μm.

[0103] Table 1

[0104] Test Example 2 The first and second active particles in Example 1 were tested using energy-dispersive X-ray spectroscopy (EDS), and the results are as follows: Figure 4 , 5 As shown, the first active particle is coated with Mo, and the second active particle is coated with Sr.

[0105] Test Example 3 The first active particle, the second active particle, and the cathode material in Example 1 were tested by inductively coupled plasma-mass spectrometry (ICP). The contents of Ni, Co, and Mn elements are shown in Table 2.

[0106] Table 2

[0107] Test Example 4 X-ray diffraction (XRD) tests were performed on the cathode material in Example 2, and the results are as follows: Figure 6 As shown, the main peaks are consistent with those of ternary cathode materials.

[0108] Test Example 5 The positive electrode material in Example 2 was prepared into a positive electrode sheet using a wet process and then tested using a scanning electron microscope (SEM).

[0109] The wet preparation process is as follows: The positive electrode material, conductive agent Super-P, and binder PVDF are mixed in a mass ratio of 94:3:3 and thoroughly stirred in NMP solvent to form a uniform positive electrode slurry. This slurry is coated onto at least one side of the positive electrode current collector aluminum foil, and after drying, rolling, die-cutting, and other processes, a positive electrode sheet meeting the requirements is obtained.

[0110] SEM results are as follows Figure 7 As shown, it can be seen that the components in the electrode are evenly distributed, and the small particles play a good filling role in the gaps between the large particles.

[0111] Test Example 6 The first active particle, the second active particle, and the positive electrode material from Example 1 were used as positive electrode active materials to prepare liquid lithium metal batteries for charge-discharge testing. The charge-discharge curves and differential capacity curves are shown below. Figures 8-10 As shown; The preparation steps for liquid lithium metal batteries are as follows: The positive electrode sheet was prepared according to Test Example 5; Lithium salt LiPF6 was dissolved in organic solvent EC-DMC (ethylene carbonate-dimethyl carbonate, 1:1 volume ratio) at a concentration of 1M to obtain a liquid electrolyte. Using pure lithium metal as the negative electrode active material and copper foil as the current collector, the negative electrode sheet that meets the requirements is obtained after processes such as die cutting. The diaphragm is a hybrid coating diaphragm with a 7μm substrate and a 3μm PVDF & ceramic mixed coating; The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. Then, one end of each of the positive electrode, separator, and negative electrode is wound around the electrolyte separator to form a core. The wound core is then placed in a pre-formed aluminum-plastic film bag. The electrolyte prepared above is injected into the baked and dried cell. After vacuum sealing, settling, and formation processes, a 1Ah battery is obtained.

[0112] Depend on Figures 8-10 It can be seen that in the cathode material, the first active particle (material A) has a high specific capacity, and its charge-discharge curve has a plateau at 4.1~4.2V, while its differential capacity curve has a characteristic peak at 4.1~4.2V, thus contributing more capacity and contributing to improved energy density. The second active particle (material B) does not have a plateau in its charge-discharge curve at 4.1~4.2V, and its differential capacity curve does not have a characteristic peak at 4.1~4.2V. The doped cathode material still maintains a high capacity, with a plateau in its charge-discharge curve at 4.1~4.2V and a characteristic peak in its differential capacity curve at 4.1~4.2V, which is beneficial for improving energy density.

[0113] Test Example 7 The first active particle and the positive electrode material in Example 1 were used as positive electrode active materials to assemble a button cell. After charging to 4.3V, the positive electrode sheet was removed and mixed with commercially available electrolyte. The mixture was placed in a high-pressure crucible for differential scanning calorimetry (DSC) testing. The results showed that the DSC peak values ​​were 200℃ and 230℃, respectively. The DSC peak temperature of the mixed material increased by 30℃, indicating that the thermal stability was significantly improved.

[0114] Test Example 8 (1) The positive electrode material in Example 1 is used as the positive electrode active material. The positive electrode active material, conductive agent Super-P and binder PVDF are mixed in a mass ratio of 94:3:3. The mixture is stirred and mixed in NMP solvent to form a uniform positive electrode slurry. The slurry is coated on at least one side of the positive electrode current collector aluminum foil. After drying, rolling, die cutting and other processes, the required positive electrode sheet is obtained. (2) Artificial graphite, conductive agent Super P (conductive carbon black), binder CMC (sodium carboxymethyl cellulose) and SBR (styrene-butadiene rubber) are mixed uniformly in a mass ratio of 95.5:1.5:1.2:1.8, and deionized water is used as the solvent. After stirring evenly to obtain a slurry, it is coated onto a copper foil current collector. The negative electrode current collector is a 6μm copper foil; and it is cut into negative electrode sheets for later use. (3) Dissolve lithium salt LiPF6 in organic solvent EC-DMC (ethylene carbonate-dimethyl carbonate, 1:1 volume ratio) at a concentration of 1M to obtain liquid electrolyte; (4) The diaphragm is a hybrid coating diaphragm with a 7μm substrate and a 3μm PVDF & ceramic mixed coating; (5) Stack the positive electrode, separator and negative electrode in sequence, so that the separator is in the middle of the positive and negative electrodes to play a role in isolation. Then, wind one end of the positive electrode, separator and negative electrode around the electrolyte separator to form a core. Then, place the rolled core in the aluminum-plastic film bag that has been punched and formed. Inject the electrolyte prepared above into the baked and dried cell. After vacuum sealing, standing and formation processes, a liquid battery with a capacity of 1Ah is obtained.

[0115] Test Example 9 (1) The positive electrode material in Example 2 is used as the positive electrode active material. The positive electrode active material, conductive agent Super-P and binder PVDF are mixed in a mass ratio of 94:3:3. The mixture is stirred and mixed in NMP solvent to form a uniform positive electrode slurry. The slurry is coated on at least one side of the positive electrode current collector aluminum foil. After drying, rolling, die cutting and other processes, the required positive electrode sheet is obtained. (2) The negative electrode active material silicon-carbon negative electrode, conductive agent Super-P (conductive carbon black) and binder PAA (polyacrylic acid) are mixed in a mass ratio of 93:3:4 and thoroughly stirred in deionized water solvent to form a uniform negative electrode slurry. The slurry is then coated onto a copper foil current collector, which is a 6μm copper foil. The slurry is then cut into negative electrode sheets for later use. (3) Dissolve lithium salt LiPF6 in organic solvent EC-DMC (ethylene carbonate-dimethyl carbonate, 1:1 volume ratio) at a concentration of 1M to obtain liquid electrolyte; (4) The organic polymer PVDF (polyvinylidene fluoride), lithium salt LiTFSI and additive LLZTO (lithium lanthanum zirconium tantalum oxide) are mixed in an organic solvent DMF (dimethylformamide) at a mass ratio of 6:4:1, coated and dried to obtain a solid electrolyte membrane. (5) Stack the positive electrode, solid electrolyte membrane and negative electrode in sequence, so that the solid electrolyte membrane is in the middle of the positive and negative electrodes, which plays the role of isolating and conducting lithium ions. Then stack the positive electrode, separator and negative electrode in sequence, place them in an aluminum-plastic film bag, inject the prepared liquid electrolyte into the baked and dried cell, and after vacuum sealing, standing, formation and other processes, a semi-solid battery with a capacity of 1Ah is obtained.

[0116] Test Case 10 (1) The positive electrode material in Example 1 is used as the positive electrode active material. The positive electrode active material, conductive agent Super-P and binder PVDF are mixed in a mass ratio of 94:3:3. The mixture is stirred and mixed in NMP solvent to form a uniform positive electrode slurry. The slurry is coated on at least one side of the positive electrode current collector aluminum foil. After drying, rolling, die cutting and other processes, the required positive electrode sheet is obtained. (2) Using pure lithium metal as the negative electrode active material and copper foil as the current collector, the negative electrode sheet that meets the requirements is obtained after die cutting and other processes. (3) The organic polymer PVDF (polyvinylidene fluoride), lithium salt LiTFSI and additive LLZTO (lithium lanthanum zirconium tantalum oxide) are mixed in an organic solvent DMF (dimethylformamide) at a mass ratio of 6:4:1, coated and dried to obtain a solid electrolyte membrane. (4) Stack the positive electrode, solid electrolyte membrane and negative electrode in sequence, so that the solid electrolyte membrane is in the middle of the positive and negative electrodes, which plays the role of isolating and conducting lithium ions. Then stack the positive electrode, separator and negative electrode in sequence, place them in an aluminum-plastic film bag, bake and dry the cell, and then go through vacuum sealing, standing, formation and other processes to obtain a solid battery with a capacity of 1Ah.

[0117] Test Examples 11-14 The difference between Test Examples 11-14 and Test Example 8 is that, in step (1), the positive electrode active material is adjusted to the positive electrode material in Examples 3, 4, 5, and 6, respectively.

[0118] The batteries prepared in Test Examples 8-14 were subjected to first discharge specific capacity test, first cycle coulombic efficiency test and 100-cycle capacity retention test, respectively. The results are shown in Table 3.

[0119] Table 3

[0120] The batteries prepared from the cathode materials provided in this application have high energy density and good cycle performance, and can be widely used in liquid batteries, semi-solid batteries and solid batteries.

[0121] In summary, the cathode material provided in this application, by controlling the differential capacity curve of the first ternary cathode material to have a characteristic peak at 4.1~4.2V, contributes more capacity and is beneficial to improving energy density. Simultaneously, by controlling the differential capacity curve of the second ternary cathode material in the second active particles to have no characteristic peak at 4.1~4.2V, better cycle performance and safety performance are ensured. This allows the cathode material composed of the first and second active particles to uniformly distribute the highly safe second ternary cathode material within the less safe first ternary cathode material system, achieving small-scale isolation of the less safe first ternary cathode material and preventing large-area thermal runaway. Thus, it balances high energy density with good cycle performance and safety performance. Therefore, the cathode material proposed in this application can effectively alleviate the problem of existing ternary cathode materials failing to effectively balance energy density and cycle performance, and has good application prospects.

[0122] Terminology In this application, "multiple" refers to two or more.

[0123] The terms “first,” “second,” “third,” “fourth,” etc., in this application (if present) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0124] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0125] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, if the method includes steps A and B, it means that the method may include steps A and B performed sequentially, or it may include steps B and A performed sequentially. For example, if the method may also include step C, it means that step C may be added to the method in any order. For example, the method may include steps A, B, and C, or it may include steps A, C, and B, or it may include steps C, A, and B, etc.

[0126] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A positive electrode material, characterized in that, Includes first active particles and second active particles; The first active particle includes a first ternary cathode material. In the first ternary cathode material, the molar percentage of nickel is greater than or equal to 80 mol% based on the total molar amount of transition metal elements other than lithium, and the differential capacity curve of the first ternary cathode material has a characteristic peak at 4.1 to 4.2 V. The second active particle includes a second ternary cathode material. In the second ternary cathode material, the molar percentage of nickel is greater than or equal to 30 mol% and less than 80 mol% based on the total molar amount of transition metal elements other than lithium. Furthermore, the differential capacity curve of the second ternary cathode material does not have a characteristic peak at 4.1 to 4.2 V.

2. The cathode material according to claim 1, characterized in that, The first active particle is a polycrystalline particle, and the second active particle is a monocrystalline particle.

3. The cathode material according to claim 1 or 2, characterized in that, The chemical formula of the first ternary cathode material is Li 1+a1 Ni x1 Co y1 Mn z1 O2, where x1+y1+z1=1, -0.1 <a1<0.2,0.8≤x1<1.0; The chemical formula of the second ternary cathode material is Li 1+a2 Ni x2 Co y2 Mn z2 O2, where x² + y² + z² = 1, -0.1 <a2<0.2,0.3≤x2<0.8。 4. The cathode material according to claim 1 or 2, characterized in that, The mass ratio of the first active particle to the second active particle is (45:55) to (95:5).

5. The cathode material according to claim 2, characterized in that, The particle size D50 of the first active particle is 6–20 μm, and the particle size D50 of the second active particle is 1–6 μm; and / or The particle size D50 of the second active particle is 0.5 to 3 μm.

6. The cathode material according to claim 2, characterized in that, The specific surface area of ​​the first active particle is 0.1–0.7 m². 2 / g; the specific surface area of ​​the second active particle is 0.5–2.0 m² / g. 2 / g.

7. The cathode material according to claim 1 or 2, characterized in that, The first active particle further includes a first doping element and a first coating element, and / or the second active particle further includes a second doping element and a second coating element; The first doping element and the second doping element are independently selected from at least one of Al, B, Ba, Bi, Ca, Cr, Ce, Co, Er, Ga, Ge, Ho, K, La, Mg, Mo, Na, Nb, Pd, P, Si, Sb, Sr, Se, Ru, Rh, Ta, Te, Ti, W, V, Y, Zr and Zn; The first coating element and the second coating element are independently selected from at least one of Al, B, Ba, Bi, Ca, Cr, Ce, Co, Er, Ga, Ge, Ho, K, La, Mg, Mo, Na, Nb, Pd, P, Si, Sb, Sr, Se, Ru, Rh, Ta, Te, Ti, W, V, Y, Zr and Zn.

8. A positive electrode sheet, characterized in that, It includes a positive current collector and a positive active material layer disposed on the positive current collector, wherein the positive active material layer includes the positive electrode material as described in any one of claims 1 to 7.

9. A battery, characterized in that, The battery includes a positive electrode sheet; the positive electrode sheet includes a positive current collector and a positive active material layer disposed on the positive current collector, the positive active material layer including the positive electrode material as described in any one of claims 1 to 7.

10. An electrical appliance, characterized in that, Includes the battery as described in claim 9, wherein the battery serves as the power supply for the electrical device.

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