CN116425137A - Titanium-doped phosphate positive electrode material, preparation method thereof and secondary battery - Google Patents
Titanium-doped phosphate positive electrode material, preparation method thereof and secondary battery Download PDFInfo
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- CN116425137A CN116425137A CN202310197183.XA CN202310197183A CN116425137A CN 116425137 A CN116425137 A CN 116425137A CN 202310197183 A CN202310197183 A CN 202310197183A CN 116425137 A CN116425137 A CN 116425137A
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- titanium
- positive electrode
- phosphate
- electrode material
- doped
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- 239000010452 phosphate Substances 0.000 title claims abstract description 201
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 title claims abstract description 200
- 239000007774 positive electrode material Substances 0.000 title claims abstract description 153
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 132
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- 229910052719 titanium Inorganic materials 0.000 claims abstract description 111
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- 238000010438 heat treatment Methods 0.000 claims description 19
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- 229910052720 vanadium Inorganic materials 0.000 claims description 8
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 7
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- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 claims description 3
- 229910002113 barium titanate Inorganic materials 0.000 claims description 3
- VKJLWXGJGDEGSO-UHFFFAOYSA-N barium(2+);oxygen(2-);titanium(4+) Chemical compound [O-2].[O-2].[O-2].[Ti+4].[Ba+2] VKJLWXGJGDEGSO-UHFFFAOYSA-N 0.000 claims description 3
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Abstract
The application belongs to the technical field of battery materials, and particularly relates to a titanium-doped phosphate positive electrode material, a preparation method thereof and a secondary battery. The preparation method of the titanium-doped phosphate positive electrode material comprises the following steps: preparing a titanium source solution and a phosphate system solution respectively; mixing the titanium source solution with the phosphate system solution, and preparing a solid precursor by a liquid phase method; and sequentially carrying out crushing treatment and sintering treatment on the solid precursor to obtain the titanium-doped phosphate positive electrode material. According to the method, the doped titanium source solution is added into the phosphate system solution, and the particle size of the phosphate system positive electrode material is refined by using the doped titanium element under the conditions that the sintering temperature is not changed and the grinding process is not increased, so that the phosphate system positive electrode material with relatively large particle size and excellent discharge performance is prepared. Simplifying the preparation process and conditions of the phosphate positive electrode material, being beneficial to providing production efficiency and being suitable for industrialized mass production and application.
Description
Technical Field
The application belongs to the technical field of battery materials, and particularly relates to a titanium-doped phosphate positive electrode material, a preparation method thereof and a secondary battery.
Background
Along with the global energy crisis and environmental protection problems becoming more and more interesting for the world, the power type lithium ion battery is more and more well seen by the global battery industry and related industries. The positive electrode material is a key part of the power type lithium ion battery, and the improvement of the performance and the reduction of the cost of the positive electrode material directly affect the whole power battery industry. Olivine-structured lithium phosphate material LiMPO 4 (M＝Fe 2+ 、Mn 2+ Etc.) are of great interest because of their very stable thermodynamic properties. The lithium iron phosphate is used as a representative, raw materials are rich in mineral sources and low in price, and the lithium iron phosphate has high market competitiveness, so that the lithium iron phosphate is the first choice positive electrode material of the current power type lithium ion battery.
The existing methods for improving the discharge performance of the phosphate positive electrode material comprise element doping, particle refinement, carbon coating and the like. The particle refinement method is generally carried out by reducing the sintering temperature or adopting a sand grinding method in the sample sintering process. However, lowering the sintering temperature affects the growth of crystals, which tends to form other structures with unstable structures, thereby affecting the discharge performance; and the sanding method can increase energy consumption and reduce productivity.
Therefore, a method or process for preparing the high-rate phosphate-based positive electrode material is still to be further studied.
Disclosure of Invention
The application aims to provide a titanium-doped phosphate positive electrode material, a preparation method thereof and a secondary battery, and aims to solve the problem that the rate performance of the existing phosphate positive electrode material needs to be improved to a certain extent.
In order to achieve the purposes of the application, the technical scheme adopted by the application is as follows:
in a first aspect, the present application provides a method for preparing a titanium doped phosphate positive electrode material, comprising the steps of:
preparing a titanium source solution and a phosphate system solution respectively;
mixing the titanium source solution with the phosphate system solution, and preparing a solid precursor by a liquid phase method;
and sequentially carrying out crushing treatment and sintering treatment on the solid precursor, and carrying out sintering treatment to obtain the titanium-doped phosphate positive electrode material.
In some possible implementations, the step of formulating the titanium source solution includes: a titanium source and a complexing agent are dissolved in water to form the titanium source solution.
In some possible implementations, the step of formulating the phosphate-based solution includes: according to the chemical general formula of LiMPO 4 The stoichiometric ratio of elements in the phosphate of (2) is obtained, and then the lithium source, the phosphorus source and the M source are dissolved in a solvent to prepare the phosphate solution; wherein the M source comprises at least one of a manganese source, a vanadium source and an iron source.
In some possible implementations, the step of sintering process includes: placing the crushed product and a first carbon source in a first inert atmosphere for one-stage sintering to obtain a semi-finished product; and placing the semi-finished product and a second carbon source in a second inert atmosphere for two-stage sintering to obtain the titanium-doped phosphate positive electrode material.
In some possible implementations, the mass ratio of the titanium source, the complexing agent, and water in the titanium source solution is (1-3) 1: (18-22).
In some possible implementations, the mass ratio of the titanium source solution to the phosphate-based solution is (0.2-2): 100.
in some possible implementations, the titanium source includes at least one of titanic acid, titanates, metatitanic acid, metatitanates, titanates, and titanates derivatives.
In some possible implementations, the complexing agent includes at least one of an organic acid, an organic acid salt.
In some possible implementations, the first carbon source and the second carbon source each independently include at least one of an organic alcohol, a saccharide.
In some possible implementations, the organic acid includes at least one of ethylenediamine tetraacetic acid, lactic acid, oxalic acid, polyhydroxyacrylic acid.
In some possible implementations, the organic acid salts include at least one of diethylenetriamine pentacarboxylate, heptonate, amino carboxylate.
In some possible implementations, the organic alcohol includes at least one of methanol, ethanol, benzyl alcohol, ethylene glycol, glycerol.
In some possible implementations, the saccharide includes at least one of starch, sucrose, glucose, fructose, maltose, lactose.
In some possible implementations, the phosphate comprises at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate.
In some possible implementations, the titanium source includes at least one of titanium chloride, barium meta-titanate, orthotitanic acid, tetrabutyl titanate, meta-titanic acid, barium titanate, lithium titanate, tetraethyl titanate, isopropyl titanate.
In some possible implementations, the flow rates of the first inert atmosphere and the second inert atmosphere are each independently 0.1-1 mL/min.
In some possible implementations, the conditions for the one-stage sintering are: heating to 300-800 ℃ at a speed of 1-5 ℃/min, preserving heat for 2-10 h, cooling and crushing.
In some possible implementations, the conditions for the two-stage sintering are: heating to 300-1000 ℃ at a speed of 1-5 ℃/min, preserving heat for 2-10 h, cooling and crushing.
In some possible implementation manners, the titanium-doped phosphate positive electrode material contains 0.5-1.5% of titanium element by mass.
In some possible implementations, the particle size D50 of the titanium doped phosphate based positive electrode material is 70-200 nm.
In some possible implementations, the compacted density of the titanium-doped phosphate positive electrode material is 2.2-2.6 g/cm 3 。
In some possible implementations, the thickness of the carbon coating layer in the titanium-doped phosphate positive electrode material is 2-5 nm.
In some possible implementations, the carbon material in the titanium-doped phosphate positive electrode material is 1-20% by mass.
In a second aspect, the present application provides a titanium doped phosphate based positive electrode material comprising a core and a carbon coating, wherein the core comprises a metal oxide having the chemical formula LiMPO 4 And titanium element doped in the phosphate, wherein M comprises at least one of Mn, fe, and V.
In some possible implementation manners, the titanium-doped phosphate positive electrode material contains 0.5-1.5% of titanium element by mass.
In some possible implementations, the thickness of the carbon coating layer in the titanium-doped phosphate positive electrode material is 2-5 nm.
In some possible implementations, the carbon material in the titanium-doped phosphate positive electrode material is 1-20% by mass.
In some possible implementations, the particle size D50 of the titanium doped phosphate based positive electrode material is 70-200 nm.
In some possible implementations, the compacted density of the titanium-doped phosphate positive electrode material is 2.2-2.6 g/cm 3 。
In a third aspect, the present application provides a secondary battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte; wherein the positive electrode comprises the titanium-doped phosphate positive electrode material prepared by the method or the titanium-doped phosphate positive electrode material.
According to the preparation method of the titanium-doped phosphate positive electrode material, the titanium source solution and the phosphate solution are respectively prepared, and then the titanium source solution and the phosphate solution are mixed, so that the titanium source is fully mixed with the phosphate precursor material in a solution state, and the titanium source is ensured to be uniformly doped in the solid precursor. After mixing, the exothermic effect of the raw material components is utilized to play a role of self-heating evaporation by a liquid phase method, so that the solvent in the mixed solution is volatilized to obtain a solid precursor. And crushing the solid precursor, and then performing sintering treatment to obtain the phosphate anode material uniformly doped with titanium element. According to the method, the doped titanium source solution is added into the phosphate system solution, and the particle size of the phosphate system positive electrode material is refined by using the doped titanium element under the conditions that the sintering temperature is not changed and the grinding process is not increased, so that the phosphate system positive electrode material with relatively large particle size and excellent discharge performance is prepared. Simplifying the preparation process and conditions of the phosphate positive electrode material, being beneficial to providing production efficiency and being suitable for industrialized mass production and application.
The second aspect of the application provides a titanium-doped phosphate positive electrode material comprising LiMPO doped with titanium element 4 A phosphate core and a carbon material coating; the titanium element doped in the inner core is beneficial to not only thinning the grain size of the phosphate positive electrode material, but also improving the multiplying power performance of the phosphate positive electrode material. The carbon material coating layer improves the structural stability of the phosphate positive electrode material, the ionic and electronic conductivity, and reduces the electrochemical properties such as the internal resistance of charge transfer. Therefore, the titanium-doped phosphate positive electrode material has more small particle distribution, and some larger particles exist in the material system, and the material system has high compaction density, high capacity, good rate performance and excellent discharge performance due to the size particle grading.
The secondary battery provided by the third aspect of the application has the characteristics of high compaction density, high capacity, good multiplying power performance, excellent discharging performance and the like, and is beneficial to improving the electrochemical performances of the secondary battery, such as energy density, circulation stability, multiplying power performance and the like, because the positive electrode contains the titanium-doped phosphate positive electrode material.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following description will briefly introduce the drawings that are needed in the embodiments or the description of the prior art, it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of a method for preparing a titanium-doped phosphate-based positive electrode material according to an embodiment of the present application;
FIG. 2 is a scanning electron microscope image of the titanium-doped phosphate-based positive electrode material provided in example 1 of the present application;
FIG. 3 is a scanning electron microscope image of the titanium doped phosphate positive electrode material provided in example 2 of the present application;
FIG. 4 is a scanning electron microscope image of the titanium doped phosphate positive electrode material provided in example 4 of the present application;
FIG. 5 is a scanning electron microscope image of the titanium doped phosphate positive electrode material provided in example 6 of the present application;
FIG. 6 is a scanning electron microscope image of the titanium-doped phosphate-based positive electrode material provided in comparative example 1 of the present application;
FIG. 7 is a scanning electron microscope image of the titanium-doped phosphate-based positive electrode material provided in comparative example 3 of the present application;
fig. 8 is a scanning electron microscope image of the titanium-doped phosphate-based positive electrode material provided in comparative example 4 of the present application.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved by the present application more clear, the present application is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.
In this application, the term "and/or" describes an association relationship of an association object, which means that there may be three relationships, for example, a and/or B may mean: a alone, a and B together, and B alone. Wherein A, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship.
In the present application, "at least one" means one or more, and "a plurality" means two or more. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c" may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.
It should be understood that, in various embodiments of the present application, the sequence number of each process does not mean that the sequence of execution is sequential, and some or all of the steps may be executed in parallel or sequentially, where the execution sequence of each process should be determined by its functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.
The terminology used in the embodiments of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this application in the examples and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The weights of the relevant components mentioned in the examples of the present application may refer not only to specific contents of the respective components but also to the proportional relationship between the weights of the respective components, and thus, it is within the scope of the disclosure of the examples of the present application as long as the contents of the relevant components are scaled up or down according to the examples of the present application. Specifically, the mass in the examples of the present application may be a mass unit known in the chemical industry such as μ g, mg, g, kg.
The terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated for distinguishing between objects such as substances from each other. For example, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX, without departing from the scope of embodiments of the present application. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature.
As shown in fig. 1, a first aspect of the embodiment of the present application provides a method for preparing a titanium-doped phosphate positive electrode material, which includes the steps of:
S10, respectively preparing a titanium source solution and a phosphate system solution;
s20, mixing a titanium source solution and a phosphate system solution, and preparing a solid precursor by a liquid phase method;
s30, crushing and sintering the solid precursor in sequence, and sintering to obtain the titanium-doped phosphate positive electrode material.
According to the preparation method of the titanium-doped phosphate positive electrode material, the titanium source solution and the phosphate solution are respectively prepared, and then the titanium source solution and the phosphate solution are mixed, so that the titanium source is fully blended with the phosphate precursor material in a solution state, and the titanium source is ensured to be uniformly doped in the solid precursor. After mixing, the exothermic effect of the raw material components is utilized to play a role of self-heating evaporation by a liquid phase method, so that the solvent in the mixed solution is volatilized to obtain a solid precursor. And crushing the solid precursor, and then sintering to obtain the phosphate anode material uniformly doped with titanium element. According to the embodiment of the application, the doped titanium source solution is added into the phosphate system solution, so that the particle size of the phosphate system positive electrode material is thinned by using the doped titanium element under the conditions of not changing the sintering temperature and not increasing the grinding process, and the phosphate system positive electrode material with relatively large particle occupation and excellent discharge performance is prepared. Simplifying the preparation process and conditions of the phosphate positive electrode material, being beneficial to providing production efficiency and being suitable for industrialized mass production and application.
In some possible implementations, in the step S10, the step of preparing the titanium source solution includes: the titanium source and complexing agent are dissolved in water to form a titanium source solution. According to the embodiment of the application, the titanium source solution is prepared in advance, so that the titanium source is uniformly dissolved in the solvent, and the doping uniformity of the titanium source is improved when the titanium source is mixed with the phosphate precursor later. The phenomena of insufficient dissolution, precipitation of dissolved substances, uneven doping and the like of the titanium source directly added into the phosphate solution are avoided. Wherein, the complexing agent is added for complexing titanium ions, improving the dissolution stability of the titanium source, so that the titanium source substance can be normally added into the phosphate solution without precipitation of insoluble substances.
In some possible implementations, the mass ratio of titanium source, complexing agent and water in the titanium source solution is (1-3) 1: (18-22). Under the condition of the proportion, the titanium source can be ensured to be fully and stably dissolved in the solution such as water, the sedimentation and precipitation of the titanium source are avoided, the dissolution stability of the titanium source is improved, and the subsequent uniform and stable doping of the titanium source into the phosphate precursor is facilitated. In some embodiments, the mass ratio of titanium source, complexing agent, and water in the titanium source solution may be 1:1:18, 1:1:19, 1:1:20, 1:1:21, 1:1:22, 2:1:18, 2:1:19, 2:1:20, 2:1:21, 2:1:22, 3:1:18, 3:1:19, 3:1:20, 3:1:21, 3:1:22, and the like.
In some possible implementations, the titanium source includes at least one of titanic acid, titanates, metatitanic acid, metatitanates, titanates, and titanate derivatives. In some embodiments, the titanium source comprises at least one of titanium chloride, barium meta-titanate, orthotitanic acid, tetrabutyl titanate, metatitanic acid, barium titanate, lithium titanate, tetraethyl titanate, isopropyl titanate. The titanium sources adopted in the embodiment have good water solubility, are favorable for being uniformly and stably doped into the post-phosphate precursor, and utilize titanium element in the compound to dope, so that the discharge performance of the positive electrode material is improved.
In some possible implementations, the complexing agent includes at least one of an organic acid, an organic acid salt. In some embodiments, the organic acid comprises at least one of ethylenediamine tetraacetic acid, lactic acid, oxalic acid, polyhydroxyacrylic acid. In some embodiments, the organic acid salt comprises at least one of diethylenetriamine pentacarboxylate, heptonate, amino carboxylate. The complexing agents adopted in the embodiment have good complexing effect on titanium ions, and the complexing effect on the titanium ions further improves the dissolution uniformity and stability of the titanium ions in the solution, so that the precipitation of dissolved matters is avoided.
In some possible implementations, the step of formulating the phosphate-based solution includes: according to the chemical general formula of LiMPO 4 The stoichiometric ratio of elements in the phosphate of (2) is obtained, and then the lithium source, the phosphorus source and the M source are dissolved in a solvent to prepare a phosphate solution; wherein the M source comprises at least one of a manganese source, a vanadium source and an iron source; the solvent includes, but is not limited to, water, methanol, ethanol, etc., as long as the lithium source, the phosphorus source, and the M source are uniformly and stably dissolved in the solvent to form a stable phosphate precursor slurry. In some embodiments, the phosphate-based solution may be formulated at a mass percent concentration of 0.5 to 1wt%, 1 to 1.5wt%, 1.5 to 2wt%, 2 to 5wt%, 5 to 10wt%, etc.
In some possible implementations, the phosphate comprises at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate. The phosphates have relatively stable structure, environmental friendliness and lower cost in the process of lithium intercalation, and have high application prospects in the anode materials of secondary batteries. Especially, the lithium iron manganese phosphate anode material has the advantages of lithium iron phosphate and lithium manganese phosphate, has higher discharge platform and energy density, and has good low-temperature working performance.
In some possible implementations, the lithium source includes at least one of lithium hydroxide, lithium oxalate, lithium acetate, lithium carbonate.
In some possible implementations, the phosphorus source includes that the phosphorus source is at least one of phosphoric acid, ammonium dihydrogen phosphate, ammonium phosphate.
In some possible implementations, the manganese source includes at least one of manganese acetate, manganese sulfate, manganese nitrate, manganese chloride.
In some possible implementations, the iron source includes at least one of ferrous sulfate, ferrous acetate, ferrous nitrate.
In some possible implementations, the vanadium source includes at least one of vanadium sulfate, vanadium nitrate, vanadium chloride.
The raw material components such as the phosphorus source, the lithium source, the manganese source, the iron source and the vanadium source adopted in the embodiment have higher solubility, can be uniformly and stably dissolved in a solvent to form a mixed solution, and are favorable for uniformly doping the titanium source into a solid precursor after being mixed with a titanium source solution.
In some possible implementations, in step S20, the titanium source solution is mixed with the phosphate solution, and the solid precursor is prepared by a liquid phase method, where the liquid phase method includes an autothermal evaporation method. The exothermic effect of the raw material components is utilized to play a role of self-heating evaporation by a liquid phase method, so that the solvent in the mixed solution is volatilized to obtain a solid precursor.
In some possible implementations, after mixing the titanium source solution with the phosphate-based solution, the mass ratio of the titanium source to the phosphate-based precursor is (0.2-2): 100, in this case, the mixing ratio of the titanium source in the mixed solution ensures that the titanium source can form a high doping amount for the phosphate-based precursor, thereby being beneficial to obtaining the phosphate-based cathode material highly doped with titanium through subsequent sintering, and improving the discharge performance of the phosphate-based cathode material by thinning the particle size of the phosphate-based cathode material through the titanium element with high doping amount. In some embodiments, after mixing the titanium source solution with the phosphate-based solution, the mass ratio of the titanium source to the phosphate-based precursor may be (0.2 to 0.5): 100. (0.5-0.8): 100. (0.8-1.0): 100. (1.0-1.3): 100. (1.3-1.6): 100. (1.6-1.8): 100. (1.8-2.0): 100, etc.
In some possible implementations, in the step S30, the step of sintering includes:
s31, placing the crushed product and a first carbon source in a first inert atmosphere for one-stage sintering to obtain a semi-finished product;
s32, placing the semi-finished product and the second carbon source in a second inert atmosphere for two-stage sintering to obtain the titanium-doped phosphate positive electrode material.
According to the embodiment of the application, the sintering treatment of the solid precursor is performed twice, so that the crystallinity of the composite material particles is improved, and the particle size is prevented from being oversized and agglomerated. Meanwhile, the carbon source added in the first-stage sintering and the second-stage sintering processes is gasified in a high-temperature calcination atmosphere of the carbon source to provide a reducing atmosphere, and the carbon source can be coated on the surface of the titanium-doped phosphate material in the sintering process to form carbon coating on the surface of the particles. The carbon source in the embodiments of the present application may be added to the calcination system in a gaseous, solid or liquid form, and the carbon source may be added prior to calcination or during sintering.
In some possible implementations, in the step S31, the conditions for the one-stage sintering are: heating to 300-800 ℃ at a speed of 1-5 ℃/min, preserving heat for 2-10 h, cooling and crushing. And (3) completing the first sintering treatment at a lower temperature, so that raw material components such as a lithium source, a manganese source, an iron source, phosphate and the like in the precursor are sintered and primarily converted into lithium iron phosphate or lithium manganese iron phosphate or lithium vanadium phosphate crystals. The first sintering process converts the titanium source doped in the phosphate-based precursor into titanium element in situ, and stably doped in the phosphate-based positive electrode material. Meanwhile, the carbon source can be coated on the surface of the titanium-doped phosphate material in the sintering process to initially form a carbon coating layer. Cooling and pulverizing to obtain semi-finished product. The semi-finished product is then placed in a second inert atmosphere containing a carbon source.
In some possible implementations, in the step S32, the conditions of the two-stage sintering are: heating to 300-1000 ℃ at a speed of 1-5 ℃/min, preserving heat for 2-10 h, cooling and crushing. The second sintering treatment is carried out under the condition of higher temperature, so that the crystallinity of the lithium iron manganese phosphate material is further improved, and the graphitization degree of the carbon material in the coating layer is improved.
According to the embodiment of the application, the primary sintering is performed at a relatively low temperature, the secondary sintering is performed at a relatively high temperature after cooling, and the sintering treatment stages at two different temperatures are beneficial to improving the crystallinity of the composite material particles and preventing the particle size from being oversized and agglomerated.
In some possible implementations, the first carbon source and the second carbon source each independently include at least one of an organic alcohol, a saccharide. In some possible implementations, the organic alcohol includes at least one of methanol, ethanol, benzyl alcohol, ethylene glycol, glycerol. In some possible implementations, the saccharide includes at least one of starch, sucrose, glucose, fructose, maltose, lactose. The carbon sources used in the above embodiments of the present application can provide a reducing atmosphere after being gasified in a high temperature calcination atmosphere, and can form carbon coatings on the particle surfaces.
In some possible implementations, the inert gas in the first inert atmosphere and the second inert atmosphere includes nitrogen, helium, argon, and the like.
In some possible implementations, the flow rates of the first inert atmosphere and the second inert atmosphere are each independently 0.1-1 mL/min. Illustratively, the flow rates of the first inert atmosphere and the second inert atmosphere are each independently 0.1 to 0.3mL/min, 0.3 to 0.5mL/min, 0.5 to 0.8mL/min, 0.8 to 1mL/min, and the like.
In some possible implementation modes, the titanium-doped phosphate positive electrode material contains 0.5-1.5% of titanium element by mass percent; under the doping condition, the titanium source has higher doping amount in the phosphate positive electrode material, and the titanium source with high doping amount is beneficial to thinning the particle size of the phosphate positive electrode material, improving the multiplying power performance of the phosphate positive electrode material, and preparing the titanium-doped phosphate positive electrode material with good multiplying power performance and more small particle distribution on the premise of not changing the sintering temperature and adopting no sanding process. In some embodiments, the titanium-doped phosphate positive electrode material may contain 0.5-0.8%, 0.8-1%, 1-1.2%, 12-1.5% by mass of titanium element, etc.
In some possible implementations, the particle size D50 of the titanium-doped phosphate-based positive electrode material is 70-200 nm; the titanium-doped phosphate positive electrode material with small particle size has high ratio, and the tap density of the positive electrode material is improved by the grading of small particles and large particles. The particle diameter D50 of the titanium-doped phosphate-based positive electrode material may be, for example, 70 to 100nm, 100 to 120nm, 120 to 150nm, 150 to 180nm, 180 to 200nm, or the like.
In some possible implementations, the thickness of the carbon coating layer in the titanium-doped phosphate-based cathode material is 2-5 nm. In some possible implementations, the carbon material in the titanium-doped phosphate positive electrode material is 1-20% by mass. In the titanium-doped phosphate positive electrode material, the thickness and the content of the carbon coating layer are not too high, if the carbon layer is too thick or the ratio is too high, the specific surface area and the compaction density of the electrode material can be affected, meanwhile, the activation transition period in the early charging period of the battery is longer, and the irreversible capacity loss is increased. In addition, the thickness and the dosage of the carbon coating layer can not be too low, if the carbon coating layer is too low, the carbon coating is incomplete, and the conductivity improvement of the phosphate electrode material is not obvious. The thickness of the carbon coating layer in the titanium-doped phosphate-based cathode material may be 2 to 3nm, 3 to 4nm, 4 to 5nm, or the like, for example. For example, the carbon material in the titanium-doped phosphate positive electrode material may be 1 to 5%, 5 to 10%, 10 to 15%, 15 to 20% by mass, and the like.
In some possible implementation modes, the compacted density of the titanium-doped phosphate positive electrode material is 2.2-2.6 g/cm 3 . Because the titanium-doped phosphate positive electrode material with small particle size has high proportion, the compaction density of the positive electrode material is improved by the small particle size and the large particle size. Illustratively, the compacted density of the titanium-doped phosphate positive electrode material is 2.2-2.3 g/cm 3 、2.3～2.4g/cm 3 、2.4～2.5g/cm 3 、2.5～2.6g/cm 3 Etc.
In a second aspect, the embodiment of the present application provides a titanium-doped phosphate-based cathode material, including a core and a carbon coating layer, where the core includes a material having a chemical formula of LiMPO 4 And titanium doped in the phosphate, wherein M comprises at least one of Mn, fe, V.
The second aspect of the embodiment provides a titanium-doped phosphate positive electrode material comprising LiMPO doped with titanium element 4 A phosphate core and a carbon material coating; the titanium element doped in the inner core is beneficial to not only thinning the grain size of the phosphate positive electrode material, but also improving the multiplying power performance of the phosphate positive electrode material. The carbon material coating layer improves the structural stability of the phosphate positive electrode material and ionsAnd electron conductivity, reducing electrochemical properties such as internal resistance of charge transfer. Therefore, the titanium-doped phosphate positive electrode material has more small particle distribution, and some larger particles exist in the material system, and the material system has high compaction density, high capacity, good rate performance and excellent discharge performance due to the size particle grading.
The titanium-doped phosphate positive electrode material provided by the embodiment of the application can be prepared by the method of the embodiment.
In some possible implementation manners, the titanium-doped phosphate positive electrode material contains 0.5-1.5% of titanium element by mass.
In some possible implementations, the thickness of the carbon coating layer in the titanium-doped phosphate-based cathode material is 2-5 nm.
In some possible implementations, the carbon material in the titanium-doped phosphate positive electrode material is 70-200 nm in mass percent.
In some possible implementations, the particle size D50 of the titanium-doped phosphate-based cathode material is 70-200 nm.
In some possible implementation modes, the compacted density of the titanium-doped phosphate positive electrode material is 2.2-2.6 g/cm 3 。
The beneficial effects of the embodiments of the present application are discussed in detail in the foregoing, and are not described herein.
A third aspect of the embodiments provides a secondary battery including a positive electrode, a negative electrode, a separator, and an electrolyte; wherein the positive electrode contains the titanium-doped phosphate positive electrode material prepared by the method or the titanium-doped phosphate positive electrode material.
The secondary battery provided by the third aspect of the embodiment of the application has the characteristics of more small particle distribution, high compaction density, high capacity, good rate performance, excellent discharge performance and the like, and is beneficial to improving the electrochemical performances of the secondary battery, such as energy density, cycle stability, rate performance and the like, because the positive electrode contains the titanium-doped phosphate positive electrode material.
In some possible implementations, the positive electrode sheet in the secondary battery includes a current collector and a positive electrode active material layer that are laminated and laminated, and the positive electrode active material layer includes the above-mentioned titanium-doped phosphate positive electrode material, a conductive agent, a binder, and the like. In some embodiments, the mass percentage of the titanium-doped phosphate positive electrode material in the positive electrode active material layer is 90% -95%. Specifically, the mass percentage of the alkali metal phosphate composite electrode material in the positive electrode active material layer may be 90%, 91%, 92%, 93%, 94%, 95%, or the like.
In some possible implementations, the preparation process of the positive electrode active material into the positive electrode sheet includes, but is not limited to: mixing the titanium-doped phosphate positive electrode material, the conductive agent and the binder to obtain electrode slurry, coating the electrode slurry on a current collector, and preparing the positive electrode plate through the steps of drying, rolling, die cutting and the like.
In some possible implementations, the content of the binder in the positive electrode active material layer is 2wt% to 5wt%. In particular embodiments, the binder content may be a typical, but non-limiting, content of 2wt%, 3wt%, 4wt%, 5wt%, etc.
In some possible implementations, the binder includes one or more of polyvinylidene chloride, soluble polytetrafluoroethylene, styrene-butadiene rubber, hydroxypropyl methylcellulose, carboxymethyl cellulose, polyvinyl alcohol, acrylonitrile copolymer, sodium alginate, chitosan derivatives.
In some possible implementations, the content of the conductive agent in the positive electrode active material layer is 1wt% to 5wt%. In specific embodiments, the content of the conductive agent may be a typical but non-limiting content of 3wt%, 4wt%, 5wt%, etc.
In some possible implementations, the conductive agent includes one or more of graphite, carbon black, acetylene black, graphene, carbon fiber, C60, and carbon nanotubes.
In some possible implementations, the positive electrode current collector includes, but is not limited to, any one of copper foil, aluminum foil.
The secondary battery can be a lithium ion battery or a lithium metal battery and other systems.
The application does not limit the negative electrode plate, the electrolyte, the diaphragm and the like in the secondary battery in the embodiment, and can be applied to any battery system.
In some possible implementations, the negative electrode of the secondary battery includes, but is not limited to, graphite, soft carbon (e.g., coke, etc.), hard carbon, etc., carbon materials, or nitrides, tin-based oxides, tin alloys, and nano-negative electrode materials, etc.
In some possible implementations, the separator includes at least one material of polypropylene fibers, polyacrylonitrile fibers, polyvinyl formal fibers, poly (ethylene terephthalate), polyethylene terephthalate, polyamide fibers, poly (paraphenylene terephthalamide).
In some possible implementations, the electrolyte includes at least one soluble lithium salt.
In order to make the implementation details and operations of the present application clearly understood by those skilled in the art, and significantly reflect the advanced performance of the titanium-doped phosphate positive electrode material and the preparation method thereof in the embodiments of the present application, the following examples are used to illustrate the technical solutions described above.
Example 1
A titanium-doped phosphate positive electrode material is prepared by the following steps:
(1) Mixing a lactic acid complexing agent and deionized water according to a metering proportion, adding a tetrabutyl titanate titanium source with titanium doping amount corresponding to 0.5% of the quality of a finished product, and stirring for dissolving to obtain a titanium source solution;
(2) Preparing a lithium iron phosphate precursor solution according to a stoichiometric ratio, and adding the titanium source solution in the step (1) into the lithium iron phosphate precursor solution to obtain a mixed solution;
(3) Evaporating and drying the mixed solution through the heat release of various raw material components in the mixed solution to obtain a titanium-doped solid lithium iron phosphate precursor;
(4) Crushing a titanium-doped solid lithium iron phosphate precursor, placing the precursor into a tube furnace, keeping the temperature at a constant temperature for 7 hours from a heating rate of 5 ℃/min to 510 ℃ under an atmosphere with a flow rate of 0.3ml/min of nitrogen and ethanol, taking out and crushing after the material is cooled to room temperature, and obtaining a semi-finished product; and then, heating the semi-finished product to 700 ℃ at a speed of 3 ℃/min under the atmosphere of nitrogen and ethanol with a flow rate of 0.3ml/min, preserving heat for 10 hours at a constant temperature, cooling, and grinding by an air flow mill to obtain the lithium iron phosphate material doped with 0.5wt% of titanium.
Example 2
A titanium-doped phosphate positive electrode material is prepared by the following steps:
(1) Mixing EDTA complexing agent and deionized water according to a metering proportion, adding a titanium source tetraethyl titanate titanium source with titanium doping amount corresponding to 0.7% of the quality of a finished product, and stirring for dissolving to obtain a titanium source solution;
(2) Preparing a lithium iron phosphate precursor solution according to a stoichiometric ratio, and adding the titanium source solution in the step (1) into the lithium iron phosphate precursor solution to obtain a mixed solution;
(3) Evaporating and drying the mixed solution through the heat release of various raw material components in the mixed solution to obtain a titanium-doped solid lithium iron phosphate precursor;
(4) Crushing a titanium-doped solid lithium iron phosphate precursor, placing the precursor into a tube furnace, keeping the temperature at a constant temperature for 7 hours from a heating rate of 5 ℃/min to 510 ℃ under an atmosphere with a flow rate of 0.3ml/min of nitrogen and ethanol, taking out and crushing after the material is cooled to room temperature, and obtaining a semi-finished product; and then, heating the semi-finished product to 700 ℃ at a speed of 4 ℃/min under the atmosphere of 0.3ml/min of nitrogen and ethanol flow rate, preserving heat for 10 hours at constant temperature, cooling, and grinding by an air flow mill to obtain the lithium iron phosphate material doped with 0.7wt% of titanium.
Example 3
A titanium-doped phosphate positive electrode material is prepared by the following steps:
(1) Mixing oxalic acid complexing agent and deionized water according to a metering proportion, adding a titanium source tetraethyl titanium source with titanium doping amount corresponding to 1.2% of the quality of a finished product, and stirring for dissolving to obtain a titanium source solution;
(2) Preparing a lithium iron phosphate precursor solution according to a stoichiometric ratio, and adding the titanium source solution in the step (1) into the lithium iron phosphate precursor solution to obtain a mixed solution;
(3) Evaporating and drying the mixed solution through the heat release of various raw material components in the mixed solution to obtain a titanium-doped solid lithium iron phosphate precursor;
(4) Crushing a titanium-doped solid lithium iron phosphate precursor, placing the precursor into a tube furnace, keeping the temperature at a constant temperature for 7 hours from a heating rate of 5 ℃/min to 510 ℃ under an atmosphere with a flow rate of 0.3ml/min of nitrogen and ethanol, taking out and crushing after the material is cooled to room temperature, and obtaining a semi-finished product; and then, heating the semi-finished product to 700 ℃ at a speed of 5 ℃/min under the atmosphere of nitrogen and ethanol with a flow rate of 0.3ml/min, preserving heat for 10 hours at a constant temperature, cooling, and grinding by an air flow mill to obtain the lithium iron phosphate material doped with 1.2wt% of titanium.
Example 4
A titanium-doped phosphate positive electrode material differs from example 1 in that: and (3) replacing the lithium iron phosphate precursor solution with the lithium iron manganese phosphate precursor solution to finally prepare the lithium iron manganese phosphate material doped with 0.5wt% of titanium.
Example 5
A titanium-doped phosphate positive electrode material differs from example 1 in that: and (3) replacing the lithium iron phosphate precursor solution with the lithium iron manganese phosphate precursor solution to finally prepare the lithium iron manganese phosphate material doped with 0.7wt% of titanium.
Example 6
A titanium-doped phosphate positive electrode material differs from example 1 in that: and (3) replacing the lithium iron phosphate precursor solution with the lithium iron manganese phosphate precursor solution to finally prepare the lithium iron manganese phosphate material doped with 1.2wt% of titanium.
Comparative example 1
A phosphate positive electrode material is prepared by the following steps:
(1) Preparing a lithium iron phosphate precursor solution according to a stoichiometric ratio, and drying to obtain a solid-phase lithium iron phosphate precursor;
(2) Crushing a solid lithium iron phosphate precursor, placing the precursor into a tube furnace, keeping the temperature at a constant temperature for 7 hours from a heating rate of 5 ℃/min to 510 ℃ under an atmosphere with a flow rate of 0.3ml/min of nitrogen and ethanol, taking out and crushing after the material is cooled to room temperature, and obtaining a semi-finished product; and then, heating the semi-finished product to 700 ℃ at a speed of 5 ℃/min under the atmosphere of nitrogen and ethanol with a flow rate of 0.3ml/min, preserving heat for 10 hours at a constant temperature, cooling, and grinding by an air flow mill to obtain the lithium iron phosphate material.
Comparative example 2
A titanium-doped phosphate positive electrode material is prepared by the following steps:
(1) Preparing a lithium iron phosphate precursor solution according to a stoichiometric ratio, and adding a tetrabutyl titanate titanium source with titanium doping amount corresponding to 0.5% of the quality of a finished product into the lithium iron phosphate precursor solution to obtain a mixed solution;
(2) Evaporating and drying the mixed solution through the heat release of various raw material components in the mixed solution to obtain a titanium-doped solid lithium iron phosphate precursor;
(3) Crushing a titanium-doped solid lithium iron phosphate precursor, placing the precursor into a tube furnace, keeping the temperature at a constant temperature for 7 hours from a heating rate of 5 ℃/min to 510 ℃ under an atmosphere with a flow rate of 0.3ml/min of nitrogen and ethanol, taking out and crushing after the material is cooled to room temperature, and obtaining a semi-finished product; and then, heating the semi-finished product to 700 ℃ at a speed of 3 ℃/min under the atmosphere of nitrogen and ethanol with a flow rate of 0.3ml/min, preserving heat for 10 hours at a constant temperature, cooling, and grinding by an air flow mill to obtain the lithium iron phosphate material doped with 0.5wt% of titanium.
Comparative example 3
A phosphate-based positive electrode material, which differs from comparative example 1 in that: and (3) replacing the lithium iron phosphate precursor solution with the lithium iron manganese phosphate precursor solution to finally prepare the titanium-undoped lithium iron manganese phosphate material.
Comparative example 4
A titanium-doped phosphate positive electrode material differs from comparative example 2 in that: and (3) changing the lithium iron phosphate precursor solution into a lithium manganese iron phosphate precursor solution, and finally preparing the lithium manganese iron phosphate material with the titanium source directly added into the precursor solution and the doping addition amount of 0.5 weight percent.
Further, to verify the advancement of the embodiments of the present application, the following performance tests were performed for each of the examples and comparative examples, respectively:
1. the morphology of the phosphate-based positive electrode materials prepared in the examples and the comparative examples is respectively observed through a scanning electron microscope, wherein the scanning electron microscope morphology graphs of the titanium-doped phosphate-based positive electrode materials prepared in the examples 1 and 2 are sequentially shown in the accompanying drawings 2 and 3, and the scanning electron microscope morphology graphs of the titanium-doped phosphate-based positive electrode materials prepared in the examples 4 and 6 are sequentially shown in the accompanying drawings 4 and 5, so that the particle size of the positive electrode material is small, and the small particle occupation ratio is large. The morphology graphs of the scanning electron microscope of the phosphate positive electrode materials prepared in comparative examples 1, 3 and 4 are shown in fig. 6, 7 and 8 in sequence, and it can be seen that the positive electrode material particles are larger and basically have large particle size.
2. Physical and chemical properties such as the compacted density of the material powder of the phosphate-based cathode materials prepared in examples and comparative examples were respectively tested, and the test results are shown in table 1 below.
3. The phosphate positive electrode materials prepared in each example and comparative example are applied to lithium ion batteries to prepare button batteries, and the specific steps are as follows:
(1) and (3) preparing slurry, namely ball-milling the phosphate positive electrode materials prepared in each example and comparative example with SP (conductive carbon black), PVDF (polyvinylidene fluoride) and NMP (N-methyl pyrrolidone) according to the mass ratio of 93.5:2.5:4:100 for 4 hours at the rotating speed of 360r/min to obtain the positive electrode slurry.
(2) Coating slurry, adjusting the scale of a scraper of a coater, uniformly coating the ball-milled slurry on an aluminum foil, placing the coated pole piece in a vacuum drying oven at 130 ℃ and baking for 3 hours;
(3) rolling and punching, namely flatly placing the aluminum foil coated with the sizing agent in the middle of a rolling shaft, and rolling the polar plate; the front surface of the rolled pole piece is clung to the punching position, and the pole pieces are punched in sequence; the compaction density of the pole piece is controlled to be 2.0-2.4 g/cm 3 The diameter is 14mm, and the thickness is 0.05-0.10 mm; placing the punched pole piece in a vacuum drying oven, and baking for 3 hours at the temperature of 130 ℃;
(4) and assembling the button cell, namely sequentially assembling the negative electrode shell, the elastic sheet, the steel sheet, the lithium sheet, the diaphragm, the positive electrode sheet and the positive electrode shell in a glove box, injecting 10 mu L of electrolyte in the process, and sealing the button cell by using a sealing machine to obtain button cells corresponding to the phosphate positive electrode materials provided by the examples and the comparative examples respectively.
The charge and discharge tests were carried out at room temperature of 25℃at different current densities of 0.1C and 1.0C. The charge and discharge tests were carried out at a low temperature of-20℃at different current densities of 0.2C and 1.0C, and the test results are shown in Table 1 below.
TABLE 1
From the test structures shown in table 1, it can be seen that the titanium-doped phosphate positive electrode material prepared in the examples of the present application has better low-temperature and low-temperature rate performance after being applied to a secondary battery system. For the lithium iron phosphate positive electrode material, the 0.1C discharge capacity of the button cell prepared by the titanium-doped phosphate positive electrode material of the embodiment 3 reaches 160mAh/g at normal temperature, and the 1C discharge capacity reaches 150mAh/g; the 0.2C discharge capacity reaches 79mAh/g at low temperature, and the 1C discharge capacity reaches 68mAh/g; the phosphate positive electrode material which is remarkably superior to the phosphate positive electrode material of the comparative example 1 and is not doped with titanium is applied to the button cell, and is also superior to the phosphate positive electrode material of the comparative example 2 in the button cell in the rate performance. Similarly, for the lithium iron manganese phosphate positive electrode material, the 0.1C discharge capacity of the button cell prepared by the titanium-doped phosphate positive electrode material of the embodiment 6 reaches 153mAh/g at normal temperature, and the 1C discharge capacity reaches 145mAh/g; the discharge capacity of 0.2C reaches 67mAh/g at low temperature, and the discharge capacity of 1C reaches 58mAh/g; the phosphate positive electrode material which is remarkably superior to the phosphate positive electrode material of the comparative example 3 and is not doped with titanium is applied to the button cell, and is also superior to the phosphate positive electrode material of the comparative example 4 in the button cell in the rate performance. Both comparative example 2 and comparative example 4 are solutions in which the direct addition of the titanium source to the phosphate precursor solution affects the stable dissolution and uniform doping of the titanium source, thereby affecting the electrochemical performance of the phosphate cathode material. In addition, the titanium-doped phosphate positive electrode material prepared by the embodiment of the application has slightly reduced compaction compared with undoped titanium due to grain refinement after titanium doping, but the improvement of the buckling performance is far greater than the slightly reduced compaction, and the energy density is relatively greatly improved.
The foregoing description of the preferred embodiments of the present application is not intended to be limiting, but is intended to cover any and all modifications, equivalents, and alternatives falling within the spirit and principles of the present application.
Claims (10)
1. The preparation method of the titanium-doped phosphate positive electrode material is characterized by comprising the following steps of:
preparing a titanium source solution and a phosphate system solution respectively;
mixing the titanium source solution with the phosphate system solution, and preparing a solid precursor by a liquid phase method;
and crushing and sintering the solid precursor in sequence to obtain the titanium-doped phosphate positive electrode material.
2. The method for preparing a titanium-doped phosphate-based positive electrode material according to claim 1, wherein the step of preparing the titanium source solution comprises: dissolving a titanium source and a complexing agent in water to form the titanium source solution;
and/or the step of preparing the phosphate-based solution comprises: according to the chemical general formula of LiMPO 4 The stoichiometric ratio of elements in the phosphate of (2) is obtained, and then the lithium source, the phosphorus source and the M source are dissolved in a solvent to prepare the phosphate solution; wherein the M source comprises at least one of a manganese source, a vanadium source and an iron source;
And/or, the step of sintering treatment comprises: placing the crushed product and a first carbon source in a first inert atmosphere for one-stage sintering to obtain a semi-finished product; and placing the semi-finished product and a second carbon source in a second inert atmosphere for two-stage sintering to obtain the titanium-doped phosphate positive electrode material.
3. The method for producing a titanium-doped phosphate-based positive electrode material according to claim 2, wherein the mass ratio of the titanium source, the complexing agent and water in the titanium source solution is (1 to 3): 1: (18-22);
and/or the mass ratio of the titanium source solution to the phosphate-based solution is (0.2 to 2): 100;
and/or the titanium source comprises at least one of titanic acid, titanate salt, metatitanic acid, metatitanate, titanate ester and titanate ester derivative;
and/or the complexing agent comprises at least one of organic acid and organic acid salt;
and/or, the first carbon source and the second carbon source each independently include at least one of an organic alcohol and a saccharide.
4. The method for producing a titanium-doped phosphate-based positive electrode material according to claim 3, wherein the organic acid comprises at least one of ethylenediamine tetraacetic acid, lactic acid, oxalic acid, and polyhydroxyacrylic acid;
And/or the organic acid salt comprises at least one of diethylenetriamine pentacarboxylate, heptonate and amino carboxylate;
and/or the organic alcohol comprises at least one of methanol, ethanol, benzyl alcohol, ethylene glycol and glycerol;
and/or the saccharide comprises at least one of starch, sucrose, glucose, fructose, maltose, lactose starch, sucrose, glucose, fructose, maltose and lactose.
5. The method for producing a titanium-doped phosphate-based positive electrode material according to claim 2, wherein the phosphate comprises at least one of lithium iron phosphate, lithium manganese phosphate, and lithium vanadium phosphate;
and/or the titanium source comprises at least one of titanium chloride, barium meta-titanate, orthotitanic acid, tetrabutyl titanate, metatitanic acid, barium titanate, lithium titanate, tetraethyl titanate and isopropyl titanate;
and/or the flow rates of the first inert atmosphere and the second inert atmosphere are respectively and independently 0.1-1 mL/min.
6. The method for producing a titanium-doped phosphate-based positive electrode material according to claim 2, wherein the one-stage sintering conditions are: heating to 300-800 ℃ at a speed of 1-5 ℃/min, preserving heat for 2-10 h, cooling and crushing;
And/or, the two-stage sintering conditions are as follows: heating to 300-1000 ℃ at a speed of 1-5 ℃/min, preserving heat for 2-10 h, cooling and crushing.
7. The method for producing a titanium-doped phosphate positive electrode material according to any one of claims 1 to 6, wherein the titanium-doped phosphate positive electrode material comprises 0.5 to 1.5% by mass of titanium;
and/or the particle diameter D50 of the titanium-doped phosphate positive electrode material is 70-200 nm;
and/or the compacted density of the titanium-doped phosphate positive electrode material is 2.2-2.6 g/cm 3 ；
And/or the thickness of the carbon coating layer in the titanium-doped phosphate positive electrode material is 2-5 nm;
and/or the mass percentage of the carbon material in the titanium-doped phosphate positive electrode material is 1-20%.
8. A titanium-doped phosphate positive electrode material is characterized by comprising a core and a carbon coating layer, wherein the core comprises a compound having a chemical formula of LiMPO 4 And titanium element doped in the phosphate, wherein M comprises at least one of Mn, fe, and V.
9. The titanium-doped phosphate positive electrode material according to claim 8, wherein the titanium element is contained in the titanium-doped phosphate positive electrode material in an amount of 0.5 to 1.5% by mass;
And/or the thickness of the carbon coating layer in the titanium-doped phosphate positive electrode material is 2-5 nm;
and/or the mass percentage of the carbon material in the titanium-doped phosphate positive electrode material is 1-20%;
and/or the particle diameter D50 of the titanium-doped phosphate positive electrode material is 70-200 nm;
and/or the compacted density of the titanium-doped phosphate positive electrode material is 2.2-2.6 g/cm 3 。
10. A secondary battery, characterized in that the secondary battery comprises a positive electrode, a negative electrode, a separator, and an electrolyte; wherein the positive electrode comprises the titanium-doped phosphate positive electrode material prepared by the method of any one of claims 1 to 7 or the titanium-doped phosphate positive electrode material of any one of claims 8 to 9.
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| CN105470510A (en) * | 2016-01-11 | 2016-04-06 | 山东玉皇新能源科技有限公司 | Modified lithium iron manganese phosphate positive electrode material and preparation method therefor |
| CN110085839A (en) * | 2019-05-07 | 2019-08-02 | 佛山市德方纳米科技有限公司 | Iron phosphate compound anode material of lithium and its preparation method and application |
| CN112897491A (en) * | 2021-01-21 | 2021-06-04 | 广东邦普循环科技有限公司 | Preparation method and application of lithium iron phosphate anode material |
| CN114538401A (en) * | 2021-07-12 | 2022-05-27 | 万向一二三股份公司 | Preparation method of high-compaction lithium iron phosphate |
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