Cathode active material, method for preparing the same, secondary battery and electronic device

Abstract

A cathode active material includes a first lithium-containing phosphate particle; and a second lithium-containing phosphate particle, at least partially embedded in the first lithium- containing phosphate particle. A first lithium-containing phosphate and a second lithium- containing phosphate independently have a formula of LiMPO4, where M includes at least one selected from Fe, Mn, Ti, V, Nb and Sn.

Description

[0001] CATHODE ACTIVE MATERIAL, METHOD FOR PREPARING THE SAME, SECONDARY BATTERY AND ELECTRONIC DEVICE

[0002] FIELD

[0003] The present disclosure relates to the technical field of batteries, and more particularly to a cathode active material, a method for preparing a cathode active material, a secondary battery and an electronic device.

[0004] BACKGROUND

[0005] At present, a lithium-containing phosphate is a common cathode active material for secondary batteries, and is normally produced by a solid-phase process. The lithium- containing phosphate products have large secondary particles aggregated by many small particles (i.e., primary particles), but it is difficult to control the size and roundness of the secondary particles, and the compaction density thereof is low. In order to improve the compaction density, in an existing preparation method, large, medium, and small particles with different particle sizes are mixed for one batch.

[0006] However, addition of the large particles will increase polarization of the material, affecting the capacity utilization, and addition of the small particles will increase the specific surface area of the material, affecting the processing performance of the material in the subsequent processes. In addition, the large, medium, and small particles generally are prepared by separate calcinating, mixing, and secondary calcinating, resulting in complex processes and high costs.

[0007] Therefore, there is still a need for providing a lithium-containing phosphate having an improved compaction density.

[0008] SUMMARY

[0009] The present disclosure provides a cathode active material, a method for preparing a cathode active material, a secondary battery and an electronic device.

[0010] In a first aspect, embodiments of the present disclosure provide a cathode active material. The cathode active material includes a first lithium-containing phosphate particle; and a second lithium-containing phosphate particle, at least partially embedded in the first lithium-containing phosphate particle. A first lithium-containing phosphate and a second lithium-containing phosphate independently have a formula of LiMPCh, where M comprises at least one selected from Fe, Mn, Ti, V, Nb and Sn. In some embodiments, the first lithium-containing phosphate and the second lithium- containing phosphate independently have a formula of LiFei-xNxPO4, where 0.001 <X^ 1, and N is selected from Mn, Ti, V, Nb and Sn.

[0011] In some embodiments, the first lithium-containing phosphate and the second lithium- containing phosphate are independently selected from lithium manganese iron phosphate, lithium manganese phosphate, lithium titanium iron phosphate, lithium titanium phosphate, lithium vanadium iron phosphate, lithium vanadium phosphate, lithium niobium iron phosphate, lithium niobium phosphate, lithium tin iron phosphate and lithium tin phosphate; optionally from lithium manganese iron phosphate, lithium vanadium phosphate and lithium manganese phosphate.

[0012] In some embodiments, the first lithium-containing phosphate is different from the second lithium-containing phosphate.

[0013] In some embodiments, a mass ratio of the first lithium-containing phosphate particle to the second lithium-containing phosphate particle ranges from 10: 1 to 1 : 10.

[0014] In some embodiments, the first lithium-containing phosphate particle and the second lithium-containing phosphate particle form a heterostructure.

[0015] In some embodiments, the first lithium-containing phosphate particle and / or the second lithium-containing phosphate particle is coated with carbon.

[0016] In some embodiments, the cathode active material has a specific surface area of 10 m2 / g to 20 m2 / g; and / or a median particle size (Dv50) of 1 pm to 1.5 pm.

[0017] In some embodiments, the cathode active material has a compaction density measured at 3 tons of greater than 2.55g / cm3.

[0018] In a second aspect, embodiments of the present disclosure provide a method for preparing a cathode active material. The method includes: preparing a first lithium- containing phosphate particle with a pore structure having at least one macropore; forming a second lithium-containing phosphate particle in the at least one macropore of the pore structure in situ, to obtain a cathode active material. The second lithium-containing phosphate particle is at least partially embedded in the first lithium-containing phosphate particle; and a first lithium-containing phosphate and a second lithium-containing phosphate independently have a formula of LiMPO4, where M comprises at least one selected from Fe, Mn, Ti, V, Nb and Sn.

[0019] In some embodiments, preparing the first lithium-containing phosphate particle includes: adding a first metal source material, a first phosphorus source material and a first lithium source material into a first solvent, performing mixing and grinding to obtain a first mixed slurry; adding a template agent to the first mixed slurry, performing drying, calcinating, and crushing to obtain a crushed product; and removing the template agent from the crushed product to obtain the first lithium-containing phosphate particle.

[0020] In some embodiments, adding the first metal source material, the first phosphorus source material, and the first lithium source material into the first solvent, performing mixing and grinding to obtain the first mixed slurry includes: mixing the first metal source material, the first phosphorus source material and the first lithium source material to obtain a first mixture, wherein a relationship among moles of a metal element of the first metal source material, phosphorus and lithium is 1 : 1: (1-1.05); and adding the first mixture into the first solvent to obtain the first mixed slurry. A solid in the first mixed slurry has a particle size of 0.4 pm to 0.6 pm; and / or a solid content of the first mixed slurry is ranged from 10wt% to 50wt%.

[0021] In some embodiments, preparing the first lithium-containing phosphate particle further includes: mixing a first carbon source material with the first metal source material, the first phosphorus source material and the first lithium source material to obtain the first mixture, wherein an amount of the first carbon source material is from 10wt% to 15wt% based on a total weight of the first metal source material, the first phosphorus source material, and the first lithium source material.

[0022] In some embodiments, preparing the first lithium-containing phosphate particle further includes: adding an additional metal source material into the first solvent. An amount of the additional metal source material is 2000ppm to 5000ppm.

[0023] In some embodiments, a mass ratio of the template agent to the first mixture is 1 :5 to 4:5.

[0024] In some embodiments, the template agent is silicon dioxide balls or silica microspheres, the template agent is removed by acid etching or alkali etching; or the template agent is polystyrene, the template agent is removed by calcination.

[0025] In some embodiments, forming the second lithium-containing phosphate particle in the at least one macropore of the pore structure in situ, to obtain the cathode active material includes: adding a second metal source material, a second phosphorus source material, a second lithium source material, and an optional second carbon source material into a second solvent, performing mixing and grinding to obtain a second mixed slurry; and adding the first lithium-containing phosphate particle to the second mixed slurry, performing drying, calcinating, and crushing to obtain the cathode active material.

[0026] In some embodiments, the calcinating comprises a first calcinating at a temperature from 200 °C to 280 °C, a second calcinating at a temperature from 350 to 400 °C, and a third calcinating at a temperature from 720 to 780 °C.

[0027] In a third aspect, embodiments of the present disclosure provide a secondary battery including a cathode active material according to any one of the embodiments of the first aspect, or a cathode active material prepared by the method according to any one of the embodiments of the second aspect.

[0028] In a fourth aspect, embodiments of the present disclosure provide an electronic device including the battery according to any one of the embodiments in the third aspect.

[0029] According to the embodiments of the present disclosure, the second lithium-containing phosphate particle is at least partially embedded in the first lithium-containing phosphate particle, such that the cathode active material has an improved compaction density. In addition, the method for preparing the cathode active material has a simple preparation process and low cost. The secondary battery including the cathode active material has improved electrochemical performance.

[0030] Additional aspects and advantages of the present disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure.

[0031] DETAILED DESCRIPTION

[0032] Embodiments of the present disclosure are described in detail below. When a plurality of embodiments and modified examples are included in the following description, use in appropriate combination of characteristic portions thereof are anticipated in advance.

[0033] The embodiments described here are only part of the embodiments of the present disclosure and are not all embodiments of the present disclosure. Based on the embodiments of the present disclosure, other embodiments obtained by those skilled in the art without creative work are within the scope of the present disclosure.

[0034] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present disclosure belongs. The terms used herein is for the purpose of describing particular embodiments only and is not intended to limit the present disclosure. The terms “comprise” and “include” and any variation thereof in the description and claims of the present disclosure are intended to indicate a non-exclusive inclusion.

[0035] In the description of the embodiments of the present disclosure, the technical terms “first”, “second” and the like are only used for distinction between different objects and are not to be understood as indicating or implying relative importance or implicitly indicating a number, a particular order or a primary or secondary relationship of the technical features. In the description of the embodiments of the present disclosure, “a plurality of’ means two or more, unless specified otherwise.

[0036] Terms used herein in embodiments of the present disclosure are only for the purpose of describing specific embodiments, but should not be construed to limit the present disclosure. As used in the embodiments of the present disclosure and the appended claims, “a / an”, and “the” in singular forms are intended to include plural forms, unless clearly indicated in the context otherwise.

[0037] When term “about” is used, this term may mean that there can be a variance in value of up to ±10%, of up to 5%, of up to 2%, of up to 1%, of up to 0.5%, of up to 0.1%, or up to 0.01%.

[0038] In the description of the present disclosure, the term “and / or”, which describes an associated relationship of associated objects, means that there may be three relationships, for example, A and / or B, which may mean that A exists alone, A and B exist at the same time, and B exists alone. A character “ / ” generally indicates that contextual objects are in an “or” relationship.

[0039] In the description of the present disclosure, the term “range” disclosed in the present disclosure is defined in the form of a lower limit and an upper limit, a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The range defined in this way can be inclusive or exclusive, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is understood that ranges of 60-110 and 80-120 are also obtained. In addition, if the listed minimum values are 1 and 2, and if the listed maximum values are 3, 4 and 5, the ranges of 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 may be obtained. In the present disclosure, unless otherwise specified, the numerical range “a-b” means the abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range “0-5” means that all the real numbers between “0-5” have been listed, and “0-5” is only the abbreviated representation of these numerical combinations. In addition, when a parameter is an integer >2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0040] In the related art, in order to improve the compaction density of the lithium-containing phosphate particle, large particles and small particles are mixed. However, the addition of the large particles will increase polarization of the cathode active material (i.e., the lithium- containing phosphate particle), affecting the capacity utilization, and the addition of the small particles will increase the specific surface area of the cathode active material, affecting the processing performance of the material in the subsequent processes. In addition, the large particles and the small particles generally are prepared by separate calcinating, mixing, and secondary calcinating, resulting in complex processes and high costs.

[0041] Therefore, an object of the present disclosure is to provide a cathode active material of lithium-containing phosphate particles, which has a high compaction density.

[0042] In a first aspect, embodiments of the present disclosure provide a cathode active material. The cathode active material includes a first lithium-containing phosphate particle; and a second lithium-containing phosphate particle, at least partially embedded in the first lithium-containing phosphate particle. A first lithium-containing phosphate and a second lithium-containing phosphate independently have a formula of LiMPCh, where M includes at least one selected from Fe, Mn, Ti, V, Nb and Sn.

[0043] According to the cathode active material in the embodiments of the present disclosure, the second lithium-containing phosphate particle is at least partially embedded in the first lithium-containing phosphate particle, such that the cathode active material has an improved compaction density, resulting in better electrochemical performances. Without wishing to be bound by any theory, the first lithium-containing phosphate particle has a macropore formed by a template to allow the second lithium-containing phosphate particle to form in the first lithium-containing phosphate particle. During the formation of the second lithium-containing phosphate particle, the first and second particles may have close contact to each other, reducing the gaps between the two particles, and thus improving the compaction density of the final cathode active material prepared.

[0044] In some embodiments, the first lithium-containing phosphate and the second lithium- containing phosphate may be independently selected from lithium iron phosphate, lithium manganese iron phosphate, lithium manganese phosphate, lithium titanium iron phosphate, lithium titanium phosphate, lithium vanadium iron phosphate, lithium vanadium phosphate, lithium niobium iron phosphate, lithium niobium phosphate, lithium tin iron phosphate and lithium tin phosphate. In some embodiments, the first lithium-containing phosphate and the second lithium- containing phosphate may be independently selected from lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate and lithium manganese phosphate.

[0045] In some embodiments, the first lithium-containing phosphate and the second lithium- containing phosphate independently have a formula of LiFei-xNxPCh, where 0.001 <X^ 1, and N is selected from Mn, Ti, V, Nb and Sn.

[0046] For example, when X=l, the first lithium-containing phosphate and the second lithium- containing phosphate may be LiMnPCh, LiTiPCh, LiVPCh, LiNbPCh, or LiSnPCh. When 0.001 < X < 1, the first lithium-containing phosphate and the second lithium-containing phosphate may be LiFei.xMnxPO4, LiFei-xTixPCh, LiFei-xVxPCh, LiFei-xNbxPCh, or LiFei- xSnxPCh. For example, when x = 0.4, the first lithium-containing phosphate and the second lithium-containing phosphate may be LiFeo.6Mno.4PO4, LiFeo.6Tio.4PO4, LiFeo.6Vo.4PO4, LiFeo.6Nbo.4PO4, or LiFeo.6Sno.4PO4.

[0047] Specific lithium-containing phosphates are provided in the above embodiments. Selection of the phosphates may further improve performances of a battery including the lithium-containing phosphate as the cathode active material. It should be noted that the first lithium-containing phosphate may be the same as or different from the second lithium- containing phosphate.

[0048] In some embodiments, the first lithium-containing phosphate is different from the second lithium-containing phosphate.

[0049] In some embodiments, a mass ratio of the first lithium-containing phosphate particle to the second lithium-containing phosphate particle ranges from 10: 1 to 1 : 10; optionally from 5: 1 to 1 :5; and optionally from 10:3 to 3 : 10. The mass ratio of the first lithium-containing phosphate particle and the second lithium-containing phosphate particle is in any of the above ranges, further improving the compaction density of the final product.

[0050] In some embodiments, the first lithium-containing phosphate particle and the second lithium-containing phosphate particle form a heterostructure.

[0051] When the first lithium-containing phosphate is different from the second lithium- containing phosphate, the cathode active material is prone to forming the heterostructure. The heterostructure may improve the stability of the cathode active material and improve the electrochemical performance.

[0052] In some embodiments, the cathode active material has a specific surface area of 10 m2 / g to 20 m2 / g; and / or a median particle size (Dv50) of 1 pm to 1.5 pm. In some embodiments, the cathode active material has a specific surface area of 12 m2 / g to 18 m2 / g; and / or a median particle size (Dv50) of 1.2 pm to 1.4 pm.

[0053] The cathode active material has an appropriate specific surface area and an appropriate median particle size, which is beneficial for the subsequent processing of materials.

[0054] In some embodiments, the cathode active material has a compaction density measured at 3 tons according to GB / T 30835-2014 of greater than 2.55 g / cm3, optionally, greater than 2.60 g / cm3.

[0055] The cathode active material has a high compaction density, such that a capacity of a secondary battery including the cathode active material is improved.

[0056] In a second aspect, embodiments of the present disclosure provide a method for preparing a cathode active material. The method includes SI : preparing a first lithium-containing phosphate particle with a pore structure having at least one macropore; and S2: forming a second lithium-containing phosphate particle in the macropore of the pore structure in situ, to obtain a cathode active material. The second lithium-containing phosphate particle is at least partially embedded in the first lithium-containing phosphate particle; and a first lithium-containing phosphate and a second lithium-containing phosphate independently have a formula of LiMPCh, where M comprises at least one selected from Fe, Mn, Ti, V, Nb and Sn.

[0057] The cathode active material prepared by the method in the second aspect may be the cathode active material in the first aspect. The first lithium-containing phosphate particle and the second lithium-containing phosphate particle in the second aspect may be the first lithium-containing phosphate particle and the second lithium-containing phosphate particle in the first aspect, respectively.

[0058] According to the method for preparing the cathode active material in the embodiments of the present disclosure, the cathode active material has an improved compaction density and better electrochemical performances. Without wishing to be bound by any theory, the first lithium-containing phosphate particle has a macropore formed by the template to allow the second lithium-containing phosphate particle to form in the first lithium-containing phosphate particle. During the formation of the second lithium-containing phosphate particle, the first and second particles may have close contact to each other, reducing the gaps between the two particles, and thus improving the compaction density of the final cathode active material prepared.

[0059] In some embodiments, a diameter of the macropore is from 200 nm to 1000 nm, optionally 300 nm to 500 nm; and / or a specific surface area of the first lithium-containing phosphate particle is from 30 m2 / g to 80 m2 / g, optionally 40 m2 / g to 60 m2 / g.

[0060] In some embodiments, SI includes: adding a first metal source material, a first phosphorus source material, and a first lithium source material into a first solvent, performing mixing and grinding to obtain a first mixed slurry; adding a template agent to the first mixed slurry, performing drying, calcinating, and crushing to obtain a crushed product; and removing the template agent from the crushed product to obtain the first lithium- containing phosphate particle.

[0061] In SI, by adding the template agent, the lithium-containing phosphate particle is attached to the template agent for growth, and then the template agent is removed to obtain the lithium-containing phosphate particle with at least one three-dimensional macropore.

[0062] In some embodiments, a mass ratio of the template agent to the first mixed slurry is 5:1 to 5:4, optionally, 10:3 to 5:3, such as 5:2, or 2: 1.

[0063] The template agent is added into the first mixed slurry by stirring using a mixer. A stirring speed may be controlled at 50 r / min to 150 r / min for 10 min to 40 min.

[0064] In some embodiments, the template agent may be silicon dioxide balls or silica microspheres, and the template agent may be removed by acid etching or alkali etching. The silicon dioxide ball or the silica microsphere has a diameter ranging from 200 nm to 1000 nm, optionally 300 nm to 500 nm. For example, the silicon dioxide balls or silica microspheres may be removed by using hydrofluoric acid having a concentration of 4 to 8 mol / L, and an etching time may be range from 0.5 h to 2 h.

[0065] Alternatively, the template agent may be polystyrene, and the template agent is removed by calcination.

[0066] In some embodiments, adding the first metal source material, the first phosphorus source material, and the first lithium source material into the first solvent, performing mixing and grinding to obtain the first mixed slurry includes: mixing the first metal source material, the first phosphorus source material and the first lithium source material to obtain a first mixture, where a relationship among moles of a metal element of the first metal source material, phosphorus and lithium is 1 : 1 : (1-1.05); and adding the first mixture into the first solvent to obtain the first mixed slurry. A solid in the first mixed slurry has a particle size of 0.4 pm to 0.6 pm; and / or a solid content of the first mixed slurry is ranged from 10 wt% to 50 wt%.

[0067] In some embodiments, SI further includes: mixing a first carbon source material with the first metal source material, the first phosphorus source material and the first lithium source material to obtain the first mixture. In some embodiments, an amount of the first carbon source material is from 10wt% to 15wt% based on a total weight of the first metal source material, the first phosphorus source material, and the first lithium source material.

[0068] In some embodiments, SI further includes: adding an additional metal source material (different from the first metal source material) into the first solvent. An amount of the additional metal source material is 2000ppm to 5000ppm, optionally, 3000ppm to 4000ppm. For example, the first metal source material provides Fe element, and the additional metal source material may provide at least one selected from Mn, Ti, V, Nb and Sn. For example, the additional metal source material includes at least one selected from titanium dioxide, manganese carbonate, manganese oxide, ammonium metavanadate, vanadium pentoxide, niobium trioxide, and tin tetrachloride.

[0069] In some embodiments, S2 includes adding a second metal source material, a second phosphorus source material, a second lithium source material, and an optional second carbon source material into a second solvent, performing mixing and grinding to obtain a second mixed slurry; adding the first lithium-containing phosphate particle to the second mixed slurry, performing drying, calcinating, and crushing to obtain the cathode active material.

[0070] In S2, the first lithium-containing phosphate particle with the pore structure having at least one macropore may be used as a template to allow the second lithium-containing phosphate particle to grow in the macropore, such that the second lithium-containing phosphate particle is at least partially embedded in the macropore of the first lithium- containing phosphate particle. In this way, the macropore of the first lithium-containing phosphate particle is filled by the second lithium-containing phosphate particle to obtain the cathode active material, such that the roundness of the first lithium-containing phosphate particle is improved, and the compaction density of the cathode active material is increased, thereby improving the capacity of the secondary battery including the cathode active material. For example, the cathode active material may have a specific surface area of 10 m2 / g to 20 m2 / g, a median particle size (Dv50) of 1 pm to 1.5 pm, and a compaction density measured at 3 tons of greater than 2.55 g / cm3.

[0071] In addition, the carbon source is added during the preparations of the first and second lithium-containing phosphate particles to allow the first lithium-containing phosphate particle and the second lithium-containing phosphate particle to be coated with carbon, such that a barrier may be formed between the first lithium-containing phosphate particle and the second lithium-containing phosphate particle. In this way, the first lithium-containing phosphate particle and the second lithium-containing phosphate particle will not grow together, they are separate phases, which further improves the electrical performances of the final product.

[0072] In some embodiments, the first metal source material, the first phosphorus source material, the first lithium source material, and the first carbon source material in SI may be the same as or different from the second metal source material, the second phosphorus source material, the second lithium source material, and the second carbon source material in S2, respectively.

[0073] In some embodiments, the first metal source material and the second metal source material may be iron source material, and may independently include at least one selected from anhydrous iron phosphate, dihydrate iron phosphate, iron oxide, and iron oxalate.

[0074] In some embodiments, the first phosphorus source material and the second phosphorus source material may independently include at least one selected from iron phosphate, phosphoric acid, diammonium phosphate, sodium dihydrogen phosphate, lithium dihydrogen phosphate, and lithium-containing phosphate.

[0075] In some embodiments, the first lithium source material and the second lithium source material may independently include at least one selected from lithium carbonate, lithium hydroxide, lithium dihydrogen phosphate, lithium-containing phosphate, and lithium citrate.

[0076] In some embodiments, the first carbon source material and the second carbon source material may be independently selected from sucrose, glucose, polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), citric acid, graphene, carbon nanotubes, and carbon black.

[0077] In some embodiments, in SI or S2, drying includes spray drying. In some embodiments, drying includes; using a nebulizer, controlling an inlet temperature to be in a range of 250°C to 280°C and an outlet temperature to be in a range of 90°C to 105°C, and adjusting a cyclone pressure difference to control a moisture content of a dried material to be less than 2% and a partical size of the dried material to be within 20pm to 30pm.

[0078] In some embodiments, in SI or S2, calcinating includes: calcinating at a first temperature of 200 °C to 280 °C for Ih to 3 h in a calcinating furnace under nitrogen protection, calcinating at a second temperature of 350 °C to 400 °C for Ih to 3h, calcinating at a third temperature ranging from 720 °C to780 °C for 8h tolOh. A heating rate is in a range of 2 to 5 °C / min. A product obtained after the calcinating is cooled to a room temperature.

[0079] In some embodiments, in SI or S2, crushing includes crushing by using an airflow crusher.

[0080] The method for preparing the cathode active material has a simple preparation process and low cost.

[0081] In a third aspect, embodiments of the present disclosure provide a secondary battery including a cathode active material according to any one of the embodiments of the first aspect, or a cathode active material prepared by the method according to any one of the embodiments of the second aspect of the present disclosure.

[0082] In some embodiments, the secondary battery may be a lithium-ion secondary battery. The lithium-ion secondary battery includes a positive electrode plate, a negative electrode plate and an electrolyte. In the lithium-ion secondary battery, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. The positive electrode film layer includes the cathode active material according to any one of the embodiments in the first aspect of the present disclosure, or the cathode active material prepared by the method according to any one of the embodiments of the second aspect of the present disclosure.

[0083] As an example, the positive electrode current collector has two surfaces along a thickness direction thereof and facing in opposite directions, and the positive electrode film layer is provided on either or both of the two surfaces.

[0084] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil may be used. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metallic material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a substrate of a high molecular material such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0085] In some embodiments, the positive electrode film layer optionally includes a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylenehexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0086] In some embodiments, the positive electrode film layer optionally includes a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0087] In some embodiments, the positive electrode plate may be prepared by: dispersing the above- mentioned components for preparing the positive electrode plate, such as the cathode active material, the conductive agent, the binder and any other components in a solvent (such as N-methyl pyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and obtaining the positive electrode plate after drying, cold pressing and other processes.

[0088] In the lithium-ion secondary battery, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector. The negative electrode film layer includes an anode material.

[0089] As an example, the negative electrode current collector has two surfaces along a thickness direction thereof and facing in opposite directions, and the negative electrode film layer is provided on either or both of the two surfaces.

[0090] In some embodiments, the negative current collector may be a metal foil or a composite current collector. For example, as the metal foil, a copper foil may be used. The composite current collector may include a polymeric material substrate and a metal layer formed on at least one surface of the polymeric material substrate. The composite current collector may be formed by forming a metallic material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a substrate of a high molecular material such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0091] In some embodiments, the anode material may be an anode material known in the art for a battery. As an example, the anode material may include at least one selected from artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials and lithium titanate. The silicon-based material may be at least one selected from elemental silicon, siliconoxygen compounds, silicon-carbon complexes, silicon-nitrogen complexes, and silicon alloys. The tin-based material may be at least one selected from elemental tin, tin oxide compounds, and tin alloys. The present disclosure is not limited to these materials, and other materials that may be used as an anode material for a battery may be used. These anode materials may be used separately or in combination (for example two or more kinds of materials are used).

[0092] In some embodiments, the negative electrode film layer optionally includes a binder. The binder may be at least one selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

[0093] In some embodiments, the negative electrode film layer optionally includes a conductive agent. The conductive agent may be at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0094] In some embodiments, the negative electrode film layer optionally includes other adjuvants, such as thickeners (e.g. sodium carboxymethylcellulose (CMC-Na)).

[0095] In some embodiments, the negative electrode plate may be prepared by: dispersing the above- mentioned components for preparing the negative electrode sheet, such as the anode material, the conductive agent, the binder and any other components in a solvent (such as deionized water) to form a negative electrode slurry; coating the negative electrode slurry on the negative electrode current collector, and obtaining the negative electrode plate after drying, cold pressing and other processes.

[0096] In the lithium-ion secondary battery, the electrolyte serves to conduct ions between the positive electrode plate and the negative electrode plate. The kind of the electrolyte is not particularly limited in the present disclosure, and may be selected according to requirements. For example, the electrolyte may be liquid, gel, or solid.

[0097] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte includes an electrolyte salt and a solvent.

[0098] In some embodiments, the electrolyte salt may include at least one selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonimide, lithium bi s-trifluorom ethane sulfonimide, lithium triflate, lithium difluorophosphate, lithium difluorooxalato borate, lithium dioxalato borate, lithium difluorooxalato phosphate, and lithium tetrafluorooxalato phosphate.

[0099] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0100] In some embodiments, the electrolyte optionally includes an additive. For example, the additive may include a negative electrode film-forming additive, a positive electrode film-forming additive, and may further include an additive capable of improving properties of the battery, such as an additive for improving overcharge properties of the battery, and an additive for improving high-temperature or low-temperature properties of the battery.

[0101] In some embodiments, the separator is further included in the lithium-ion secondary battery. The type of the separator is not particularly limited in the present disclosure, and any known separator having a porous structure and good chemical and mechanical stability may be used.

[0102] In some embodiments, the material of the separator may be at least one selected from glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, which is not limited in the present disclosure. In a case where the separator is a multilayer composite film, the materials of individual layers may be the same or different.

[0103] In some embodiments, the battery may be a battery module or a battery pack, which may be applied in electronic devices, such as mobile terminals and vehicles.

[0104] In some embodiments, the secondary battery includes an outer package. The outer package is used to encapsulate the electrodes and the electrolyte.

[0105] In some embodiments, the outer package of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell and the like. Alternatively, the outer package of the secondary battery may be a soft package, such as a soft bag. The soft bag may be made of a polymer material such as plastics, polypropylene, polybutylene terephthalate and polybutylene succinate.

[0106] The shape of the secondary battery may be cylindrical, square or any other shape, which is not limited in the present disclosure.

[0107] The secondary battery including the cathode active material has improved electrical performance.

[0108] In a fourth aspect, embodiments of the present disclosure provide an electronic device including the battery according to any one of the embodiments in the third aspect.

[0109] In some embodiments, the electronic device may be electric cars, electric motorcycles, computers, mobile phones, and smart wearable devices.

[0110] Hereinafter, the present disclosure will be further described with Examples, but the present disclosure is not limited to these Examples.

[0111] It is noted that materials and reagents used in the embodiments may be obtained commercially or prepared according to common methods in the related art.

[0112] Examples

[0113] Inventive Example 1 (IE1)

[0114] 1000 g FePCU, 250 g Li2CO3, 100g glucose and 7 g TiCF were added into 2500 g deionized water, stirred for 10 min at 60 r / min in a stirring tank to obtain a first mixed slurry, and the first mixed slurry was ground by a sand mill at 1300 r / min to make particles in the first mixture have a Dv50 of 506 nm. 800 g of silicon dioxide pellets with an average particle size of 400 nm were added into the first mixed slurry, and stirred for 30 min to obtain a first slurry. The first slurry was subjected to spray drying to obtain a first dried material. The first dried material was placed into a furnace and calcinated at 250 °C for 2 h, 380 °C for 2h, and 750 °C for 10 h in sequence to obtain a first calcinate. The first calcinate was crushed through air flow pulverizing to obtain a crushed product. The crushed product was soaked in 6 mol / L hydrofluoric acid, and then was filtered and washed to neutral with ethanol aqueous solution, and dried to obtain a first lithium-containing phosphate particle with a three-dimensional macropore.

[0115] 1000 g FePCU, 250 g Li2CO3, 100g glucose and 7 g TiCF were added into 2500 g deionized water, stirred for 10 min at 60 r / min in a stirring tank to obtain a second mixed slurry, and the second mixed slurry was ground by a sand mill at 1300 r / min to make particles in the second mixed slurry have a Dv50 of 510 nm. 300g of the first lithium-containing phosphate particle was added into the second mixed slurry, and stirred for 30 min to obtain a second slurry. The second slurry was subjected to spray drying to obtain a second dried material. The second dried material was placed into a furnace and calcinated at 250 °C for 2 h, 380 °C for 2h, and 750 °C for lOh in sequence to obtain a second calcinate. The second calcinate was crushed through air flow pulverizing to obtain a lithium-containing phosphate cathode active material.

[0116] 80 parts by mass of the lithium-containing phosphate cathode active material, 10 parts by mass of acetylene black, and 10 parts by mass of poly vinylidene fluoride (PVDF) were evenly dispersed into N-methyl-2-pyrrolidone (NMP) to obtain a mixture slurry. The mixture slurry was applied on a surface of an aluminum foil with a thickness of 12 pm, the aluminum foil was dried at 100 °C and then rolled, and cut to a circular disc with a diameter of 12 mm to produce a positive electrode plate.

[0117] Further, a lithium metal plate is used as a negative electrode plate, a polypropylene microporous membrane is used as a separator, and 1 mol / L LiPFe / EC+DMC (with a volume ratio 1 : 1 : 1 that is, a solute of the electrolyte is LiPFe, and a solvent is a mixed solvent of ethylene carbonate and diethyl carbonate with a volume ratio of 1 : 1) is used as an electrolyte. The components are assembled to form a battery (i.e., a CR2025 coin battery) in a glove box under an argon atmosphere.

[0118] Inventive Example 2 (IE2)

[0119] A battery was produced in the same manner as in IE1 except that, the second mixed slurry was obtained by mixing and stirring 500 g FePCU, 125 g Li2CO3, 50g glucose and 2.1 g TiCh, and 500 g of the first lithium-containing phosphate particle was added into the second mixed slurry.

[0120] Inventive Example 3 (IE3)

[0121] A battery was produced in the same manner as in IE1 except that, the second mixed slurry was obtained by mixing and stirring 300 g FePCU, 75 g Li2CO3, 30g glucose and 2.1 g TiCh, and 1000 g of the first lithium-containing phosphate particle was added into the second mixed slurry.

[0122] Inventive Example 4 (IE4)

[0123] A battery was produced in the same manner as in IE1 except that, the first mixed slurry was obtained by mixing and stirring 530 g Fe2O3, 163 g LiOH, 100 g glucose, 765 g phosphoric acid (85%) and 7 g TiCh, the second mixed slurry was obtained by mixing and stirring 265 g Fe2O3, 81.5 g LiOH, 50 g glucose, 382.5 g phosphoric acid (85%) and 3.5 g TiO2, and 500 g of the first lithium-containing phosphate particle was added into the second mixed slurry.

[0124] Inventive Example 5 (IE5)

[0125] A battery was produced in the same manner as in IE1 except that, the silicon dioxide pellets were replaced with polystyrene pellets with an average particle size of 600 nm, and polystyrene pellets were removed by the calcination at 250°C for 2h, 380°C for 2h, and 750°C for lOh in sequence.

[0126] Inventive Example 6 (IE6)

[0127] A battery was produced in the same manner as in IE1 except that, the first mixture was obtained by mixing and stirring 1000 g FePCU, 250 g Li2CO3, 100g glucose and 7.2 g V2O5, the second mixture was obtained by mixing and stirring 500 g FePCU, 125 g Li2CO3, 50 g glucose, 3.6 g V2O5, and 500 g of the first lithium-containing phosphate particle was added into the second mixture.

[0128] Inventive Example 7 (IE7)

[0129] A battery was produced in the same manner as in IE1 except that, the first mixture was obtained by mixing and stirring 1000 g FePCU, 250 g Li2CO3, 100g glucose and 7 g TiCh, the second mixture was obtained by mixing and stirring 500 g FePCU,, 125 g Li2CO3, 50 g glucose, 3.6 g V2O5, and 500 g of the first lithium-containing phosphate particle was added into the second mixture.

[0130] Inventive Example 8 (IE8)

[0131] A battery was produced in the same manner as in IE1 except that, the first mixture was obtained by mixing and stirring 1000 g FePCU, 250 g Li2CO3, 100g glucose and 7 g MnO, the second mixture was obtained by mixing and stirring 500 g FePCU,, 125 g Li2CO3, 50 g glucose, 3.5 g MnO, and 500 g of the first lithium-containing phosphate particle was added into the second mixture.

[0132] Inventive Example 9 (IE9)

[0133] A battery was produced in the same manner as in IE1 except that, the first mixture was obtained by mixing and stirring 1000 g FePO4, 250 g Li2CO3, 100g glucose and 7 g TiO2, the second mixture was obtained by mixing and stirring 500 g FePO4„ 125 g Li2CO3, 50 g glucose, 3.5 g MnO, and 500 g of the first lithium-containing phosphate particle was added into the second mixture.

[0134] Comparative Example 1 (CE1)

[0135] Abattery was produced in the same manner as in IE1 except that, the first lithium-containing phosphate particle with the three-dimensional macropore was used as the cathode active material to prepare the positive electrode plate.

[0136] Comparative Example 2 (CE2)

[0137] 1000 g FePO4, 250 g Li2CO3, 100g glucose and 7 g TiCf were added into 2500 g deionized water, stirred for 10 min at 60 r / min in a stirring tank to obtain a third mixture, and then the third mixture was ground by a sand mill at 1300 r / min to make particles in the third mixture have a Dv50 of 506 nm. The third mixture was subjected to spray drying to obtain a third dried material. The third dried material was placed into a furnace and calcinated at 250 °C for 2 h, 380 °C for 2 h, and 750 °C for 10 h in sequence to obtain a third calcinate. The third calcinate was crushed to obtain a third lithium-containing phosphate particle.

[0138] A battery was produced in the same manner as in IE1 except that, the third lithium- containing phosphate particle was used as the cathode active material to prepare the positive electrode plate.

[0139] Comparative Example 3 (CE3)

[0140] 500 g of the first lithium-containing phosphate particle in CE1 and 500 g of the third lithium-containing phosphate particle in CE2 were mixed at 700 r / min for 30 min to obtain a lithium-containing phosphate cathode active material.

[0141] Abattery was produced in the same manner as in IE1 except that, the above-obtained lithium- containing phosphate cathode active material was used as the cathode active material to prepare the positive electrode plate.

[0142] Test methods

[0143] Evaluation of Compaction Density

[0144] The compaction density of the cathode active materials of Inventive Examples and Comparative Examples are measured by a compaction density instrument at a testing pressure of 3 tons according to GB / T 30835-2014.

[0145] Evaluation of Particle Size

[0146] The particle size Dv50 of the particles is measured according to GB / T 30835-2014.

[0147] Evaluation of Discharge Capacity

[0148] The batteries obtained in Inventive Examples and Comparative Examples are measured on a LAND battery testing system. The charge and discharge voltage is controlled from 2.0 V to 3.75 V. Under an environment temperature of 25°C, the batteries of Inventive Examples and Comparative Examples are charged and discharged at a constant current of 0.1C, and then are charged at 0.2C, discharged at 0.2C, charged at 0.2C, discharged at 0.5C, charged at 0.2C, and discharged at 1C. 0.1C discharge capacity and 1C discharge capacity are recorded.

[0149] Table 1 shows the compaction density of the cathode active materials of Inventive Examples and Comparative Examples, and the discharge capacity of the batteries of Inventive Examples and Comparative Examples.

[0150] Table 1

[0151] According to Table 1, for IE1 to IE9, the cathode active materials have the improved compaction density, and the batteries have improved discharge capacity at 0.1 C and 1 C.

[0152] For IE1 to IE3, the mass ratios of the first lithium-containing phosphate particle to the second lithium-containing phosphate particle are about 3 : 10, 1 : 1 and 10:3, respectively. It can be seen that when the mass ratio of the first lithium-containing phosphate particle to the second lithium-containing phosphate particle is about 1 : 1, the compaction density of the cathode active material and the discharge capacity of the secondary battery are better than Examples with other ratios.

[0153] For IE4, different metal source material, phosphorus source material and lithium source material are used; for IE5, polystyrene pellets are used as the template agent; for IE6, Ti is replaced with V in the lithium-containing phosphate particle; for IE8, Ti is replaced with Mn in the lithium-containing phosphate particle. The cathode active materials in IE4 to IE6 and IE8 obtains improved compaction density, and the secondary batteries obtain improved discharge capacity at 0.1 C and 1 C compared with Comparative Examples.

[0154] In IE7, the first lithium-containing phosphate is lithium titanium iron phosphate, and the second lithium-containing phosphate is lithium vanadium iron phosphate, such that a heterostructure is formed by the first lithium-containing phosphate particle and the second lithium-containing phosphate particle, which shows better compaction density and discharge capacity compared with other examples. In IE9, the first lithium-containing phosphate is lithium titanium iron phosphate, and the second lithium-containing phosphate is lithium manganese iron phosphate, which also shows better compaction density and discharge capacity compared with other examples.

[0155] In CE1, the cathode active material is the first lithium-containing phosphate particle with three-dimensional macropores without filling the second lithium-containing phosphate particle. It can be seen that the compaction density is relatively poor, and the discharge capacity is relatively low.

[0156] In CE2, the lithium-containing phosphate particle is naturally grown without the template for creating the macropores. It can be seen that the compaction density of the third lithium-containing phosphate particle is 2.46 g / cm3, which is lower compared with Inventive Examples. Without wishing to be bound by any theory, a “normal” growth of the third lithium- containing phosphate particle due to the same calcination conditions will not suffer from the close contact between the first lithium-containing phosphate particle and the second lithium- containing phosphate particle. The third lithium-containing phosphate particles are formed freely. It is difficult to control the particle size of the third lithium-containing phosphate particles, and thus the compaction density and the capacity performances are relatively low.

[0157] In CE3, the cathode active material is obtained by mixing the first lithium-containing phosphate particle in CE1 and the third lithium-containing phosphate particle in CE2. The two lithium-containing phosphate particles are mixed mechanically. It can be seen that both the compaction density and the discharge capacity are relatively low compared with Inventive Examples. Without wishing to be bound by any theory, a simple mechanical is not enough to fill the second lithium-containing phosphate particle into the macropore of the first lithium-containing phosphate particle.

[0158] According to the embodiments of the present disclosure, the second lithium-containing phosphate particle is at least partially embedded in the first lithium-containing phosphate particle, such that the cathode active material has the improved compaction density. The secondary battery including the cathode active material has the improved electrochemical performance.

[0159] Reference throughout this specification to “an embodiment,” “some embodiments,” “one embodiment”, “another example,” “an example,” “a specific example,” or “some examples,” means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. Thus, the appearances of the phrases such as “in some embodiments,” “in one embodiment”, “in an embodiment”, “in another example,” “in an example,” “in a specific example,” or “in some examples,” in various places throughout this specification are not necessarily referring to the same embodiment or example of the present disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0160] Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed here. This application is intended to cover any variations, uses, or adaptations of the disclosure following the general principles thereof and including such departures from the present disclosure as come within known or customary practice in the art. It is intended that the specification and examples be considered as illustrative only, with a true scope and spirit of the disclosure being indicated by the following claims.

Claims

CLAIMS1. A cathode active material, comprising: a first lithium-containing phosphate particle; and a second lithium-containing phosphate particle, at least partially embedded in the first lithium-containing phosphate particle; wherein a first lithium-containing phosphate and a second lithium-containing phosphate independently have a formula of LiMPCL, where M comprises at least one selected from Fe, Mn, Ti, V, Nb and Sn.

2. The cathode active material according to claim 1, wherein the first lithium-containing phosphate and the second lithium-containing phosphate independently have a formula of LiFei-xNxPCL, where 0.001 <X^ 1, and N is selected from Mn, Ti, V, Nb and Sn.

3. The cathode active material according to claim 1 or 2, wherein the first lithium- containing phosphate and the second lithium-containing phosphate are independently selected from lithium manganese iron phosphate, lithium manganese phosphate, lithium titanium iron phosphate, lithium titanium phosphate, lithium vanadium iron phosphate, lithium vanadium phosphate, lithium niobium iron phosphate, lithium niobium phosphate, lithium tin iron phosphate and lithium tin phosphate; optionally from lithium manganese iron phosphate, lithium vanadium phosphate and lithium manganese phosphate.

4. The cathode active material according to any one of claims 1 to 3, wherein the first lithium-containing phosphate is different from the second lithium-containing phosphate.

5. The cathode active material according to claim 4, wherein a mass ratio of the first lithium-containing phosphate particle to the second lithium-containing phosphate particle ranges from 10: 1 to 1 : 10.

6. The cathode active material according to claim 4 or 5, wherein the first lithium- containing phosphate particle and the second lithium-containing phosphate particle form a heterostructure.

7. The cathode active material according to any one of claims 1 to 6, wherein the firstlithium-containing phosphate particle and / or the second lithium-containing phosphate particle is coated with carbon.

8. The cathode active material according to any one of claims 1 to 7, wherein the cathode active material has a specific surface area of 10 m2 / g to 20 m2 / g; and / or a median particle size (Dv50) of 1 pm to 1.5 pm.

9. The cathode active material according to any one of claims 1 to 8, wherein the cathode active material has a compaction density measured at 3 tons of greater than 2.55g / cm3.

10. A method for preparing a cathode active material, comprising: preparing a first lithium-containing phosphate particle with a pore structure having at least one macropore; forming a second lithium-containing phosphate particle in the at least one macropore of the pore structure in situ, to obtain a cathode active material; wherein the second lithium-containing phosphate particle is at least partially embedded in the first lithium-containing phosphate particle; and a first lithium-containing phosphate and a second lithium-containing phosphate independently have a formula of LiMPCh, where M comprises at least one selected from Fe, Mn, Ti, V, Nb and Sn.

11. The method according to claim 10, wherein preparing the first lithium-containing phosphate particle comprises: adding a first metal source material, a first phosphorus source material and a first lithium source material into a first solvent, performing mixing and grinding to obtain a first mixed slurry; adding a template agent to the first mixed slurry, performing drying, calcinating, and crushing to obtain a crushed product; and removing the template agent from the crushed product to obtain the first lithium- containing phosphate particle.

12. The method according to claim 11, wherein adding the first metal source material, the first phosphorus source material, and the first lithium source material into the first solvent, performing mixing and grinding to obtain the first mixed slurry comprises: mixing the first metal source material, the first phosphorus source material and the firstlithium source material to obtain a first mixture, wherein a relationship among moles of a metal element of the first metal source material, phosphorus and lithium is 1 : 1 : (1-1.05); and adding the first mixture into the first solvent to obtain the first mixed slurry; wherein a solid in the first mixed slurry has a particle size of 0.4 pm to 0.6 pm; and / or a solid content of the first mixed slurry is ranged from 10wt% to 50wt%.

13. The method according to claim 11 or 12, wherein preparing the first lithium- containing phosphate particle further comprises: mixing a first carbon source material with the first metal source material, the first phosphorus source material and the first lithium source material to obtain the first mixture, wherein an amount of the first carbon source material is from 10wt% to 15wt% based on a total weight of the first metal source material, the first phosphorus source material, and the first lithium source material.

14. The method according to any one of claims 11 to 13, wherein preparing the first lithium-containing phosphate particle further comprises: adding an additional metal source material into the first solvent; wherein an amount of the additional metal source material is 2000ppm to 5000ppm.

15. The method according to any one of claims 11 to 14, wherein a mass ratio of the template agent to the first mixture is 1 :5 to 4:5.

16. The method according to any one of claims 11 to 15, wherein the template agent is silicon dioxide balls or silica microspheres, the template agent is removed by acid etching or alkali etching; or the template agent is polystyrene, the template agent is removed by calcination.

17. The method according to any one of claims 10 to 16, wherein forming the second lithium-containing phosphate particle in the at least one macropore of the pore structure in situ, to obtain the cathode active material comprises: adding a second metal source material, a second phosphorus source material, a second lithium source material, and an optional second carbon source material into a second solvent, performing mixing and grinding to obtain a second mixed slurry; and adding the first lithium-containing phosphate particle to the second mixed slurry,performing drying, calcinating, and crushing to obtain the cathode active material.

18. The method according to any one of claims 11 or 17, wherein the calcinating comprises a first calcinating at a temperature from 200 °C to 280 °C, a second calcinating at a temperature from 350 to 400 °C, and athird calcinating at a temperature from 720 to 780 °C.

19. A secondary battery comprising a cathode active material according to any one of claims 1 to 9, or a cathode active material prepared by the method according to any one of claims 10 to 18.

20. An electronic device comprising a secondary battery according to claim 19.

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