Disclosure of Invention
The invention aims to provide a ternary cathode precursor and a preparation method thereof, a ternary cathode material and a preparation method thereof, and a lithium ion battery, and aims to solve the problem that the surface of the ternary cathode material is subjected to irreversible phase change to influence the cycle performance of the battery in the battery cycle process.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a ternary anode precursor material, which comprises ternary anode precursor particles and metal phosphate coated on the surfaces of the ternary anode precursor particles, wherein metal ions in the metal phosphate are selected from at least one of lanthanum ions, neodymium ions, yttrium ions, praseodymium ions, niobium ions, tantalum ions and samarium ions.
According to the ternary anode precursor material provided by the invention, the surface of ternary anode precursor particles is coated with metal phosphate, and metal ions in the metal phosphate are selected from at least one of lanthanum ions, neodymium ions, yttrium ions, praseodymium ions, niobium ions, tantalum ions and samarium ions. The metal phosphate has good structural stability, and after the ternary positive electrode precursor particles are coated, the side reaction between the obtained ternary positive electrode material and the electrolyte can be reduced, and the cycle performance of the battery containing the ternary positive electrode material is improved; in addition, the coprecipitation of the metal phosphate coated in the precursor stage is beneficial to improving the coating uniformity and improving the cycle performance of the battery to a greater extent.
As a preferable aspect of the ternary cathode precursor material of the present invention, the ternary cathode precursor particles are doped with the metal ions, and the content of the metal ions increases in a gradient manner from inside to outside of the ternary cathode precursor material. At least one of lanthanum ion, neodymium ion, yttrium ion, praseodymium ion, niobium ion, tantalum ion and samarium ion is adopted to carry out gradient doping on the ternary anode precursor particles, so that the stability of the final ternary anode material bulk phase structure is improved, the crystal phase transformation in the cycle process of the anode material is slowed down, and the cycle performance of the ternary anode material is further improved.
As a preferable case of the ternary cathode precursor material of the present invention, the metal phosphate is at least one selected from lanthanum phosphate, neodymium phosphate, yttrium phosphate, praseodymium phosphate, niobium phosphate, tantalum phosphate, and samarium phosphate. The ternary positive electrode precursor particles are coated by the material, so that the coating uniformity of the ternary positive electrode precursor particles can be improved, the side reaction between the ternary positive electrode material formed by the ternary positive electrode precursor particles and an electrolyte is finally reduced, and the cycle performance of a battery containing the ternary positive electrode material is improved. Particularly, when the metal phosphate coating the ternary cathode precursor particles is at least one of lanthanum phosphate, neodymium phosphate and praseodymium phosphate, the lanthanum phosphate, neodymium phosphate and praseodymium phosphate have monazite structures and have very good structural stability, so that the structural stability of the coating layer can be further improved, and the influence of the electrolyte on the ternary cathode material is reduced.
As a preferable situation of the ternary cathode precursor material, the particle size of the ternary cathode precursor particles is 3-16 μm. In this case, the particle size of the ternary positive electrode precursor material is in an appropriate range, has a good compaction ratio, and is not easily broken due to an excessively large particle size.
As a preferable aspect of the ternary cathode precursor material of the present invention, the weight ratio of the metal phosphate to the ternary cathode precursor particles is 0.05% to 5%. In this case, the coating layer formed of the metal phosphate can completely cover the surface of the ternary positive electrode precursor particle. If the coating amount of the metal phosphate is too high, impurities introduced into the positive electrode active material are excessive, resulting in a decrease in gram capacity and rate performance of the positive electrode material.
The second aspect of the invention provides a preparation method of a ternary cathode precursor material, which comprises the following steps:
respectively preparing phosphoric acid or a phosphate solution, a metal salt solution and ternary anode precursor slurry, wherein metal ions in the metal salt solution are at least one selected from lanthanum ions, neodymium ions, yttrium ions, praseodymium ions, niobium ions, tantalum ions and samarium ions, and the ternary anode precursor slurry is slurry formed by ternary anode precursor particles;
and mixing and reacting the phosphoric acid or phosphate solution, the metal salt solution and the ternary anode precursor slurry, and generating metal phosphate on the surface of the ternary anode precursor particles in situ to obtain the ternary anode precursor material coated by the metal phosphate.
According to the preparation method of the ternary cathode precursor material, the metal phosphate coating layer is generated on the surface of the ternary cathode precursor through a solution coprecipitation method, so that in-situ coating of ternary cathode precursor particles can be realized, and the coating uniformity and the structural stability are improved. After the ternary anode precursor material is converted into the ternary anode material, the side reaction of the ternary anode material and the electrolyte can be reduced in the circulation process, and the circulation performance of the battery is improved. In addition, in the process of calcining the ternary cathode precursor coated in the manner after the lithium source is introduced, metal ions in the coating layer permeate into the ternary cathode material, so that metal doping of the ternary cathode material is realized, the structural stability of the ternary cathode material is improved, and the cycle performance is improved.
As an optimized situation of the preparation method of the ternary cathode precursor material, the solid content of the ternary cathode precursor slurry is 5% -50%, the molar concentration of the phosphoric acid or phosphate solution is 0.5-3 mol/L, and the concentration of metal ions in the metal salt solution is 0.05-2 mol/L. In this case, phosphoric acid or phosphate reacts with metal ions in the reaction system and is bonded on the surface of the ternary positive electrode precursor to form a uniform coating layer.
As a preferable situation of the preparation method of the ternary cathode precursor material, the temperature of the mixing reaction is 20-80 ℃. Under the temperature condition, phosphoric acid or phosphate reacts with metal ions in a reaction system, and the phosphoric acid or phosphate is combined with the surface of the ternary positive electrode precursor to form a coating layer.
As a preferable aspect of the preparation method of the ternary cathode precursor material of the present invention, the ternary cathode precursor particles are NixCoyMn1-x-y(OH)2Wherein x is more than 0 and less than 1, and y is more than 0 and less than 1; the NixCoyMn1-x-y(OH)2The preparation method comprises the following steps:
adding nickel salt, cobalt salt and manganese salt into deionized water in proportion, preparing a main metal salt solution, and providing a complexing agent and a precipitating agent;
feeding the main metal salt solution, the complexing agent and the precipitator into a reaction kettle, heating the mixture in an inert atmosphere to perform coprecipitation chemical reaction, and preparing a ternary anode precursor NixCoyMn1-x-y(OH)2。
The ternary positive electrode precursor prepared by the method has better particle size uniformity.
As a preferable aspect of the preparation method of the ternary cathode precursor material of the present invention, in the process of the heating for coprecipitation chemical reaction, the particle size of the slurry in the reaction kettle is tested, and the Ni is waited forxCoyMn1-x-y(OH)2The particle size of the slurry is 3-16 mu m, and then the feeding is stopped. Control of NixCoyMn1-x-y(OH)2Has a particle diameter of 3 to 16 μm and can be used at the same timeThe compaction and rate capability of the material, and the risk of pulverization of the material is reduced.
The third aspect of the invention provides a preparation method of a ternary cathode material, wherein the ternary cathode precursor material prepared by the preparation method provided by the first aspect of the invention is mixed with a lithium source and then calcined to prepare the ternary cathode material.
According to the preparation method of the ternary cathode material, provided by the invention, the ternary cathode precursor with the surface coated with the metal phosphate is used as a raw material, and the ternary cathode material obtained after lithium is prepared has good coating uniformity, so that the cycle performance of a battery containing the ternary cathode material can be improved. In addition, in the calcining treatment process of lithium preparation, metal ions in the coating layer permeate into the ternary cathode material, so that the structural stability of the crystal is improved, and the cycle performance of the battery containing the ternary cathode material is further improved.
The invention provides a ternary cathode material, which is prepared by the preparation method provided by the first aspect of the invention.
The ternary cathode material provided by the invention is prepared by the method, so that a coating layer formed on the surface of the ternary cathode material has better coating uniformity, and the cycle performance of a battery containing the ternary cathode material can be improved. In addition, due to the ternary cathode material prepared by the method, metal ions in the coating layer permeate into the ternary cathode material, so that the structural stability of the ternary cathode material crystal can be improved, and the cycle performance of a battery containing the ternary cathode material is further improved.
A fifth aspect of the invention provides a lithium battery comprising the ternary cathode material as provided in the fourth aspect of the invention.
The lithium battery provided by the invention contains the ternary cathode material, so that the cycle performance of the battery can be effectively improved.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application more clearly apparent, 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 merely illustrative of the present application and are not intended to limit the present application.
In this application, the term "and/or" describes an association relationship of associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a is present alone, A and B are present simultaneously, and B is present alone. Wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.
In the present application, "at least one" means one or more, "a plurality" means two or more. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, "at least one (a), b, or c", or "at least one (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, and c may be single or plural, respectively.
It should be understood that, in various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, some or all of the steps may be executed in parallel or executed sequentially, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.
The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the examples of this application 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.
In a first aspect, an embodiment of the present application provides a ternary cathode precursor material, including ternary cathode precursor particles, and a metal phosphate coated on surfaces of the ternary cathode precursor particles, where a metal ion in the metal phosphate is selected from at least one of a lanthanum ion, a neodymium ion, an yttrium ion, a praseodymium ion, a niobium ion, a tantalum ion, and a samarium ion.
In the embodiment of the application, the ternary cathode precursor is a precursor material of a ternary cathode material, and the ternary cathode material is matched with lithium to obtain the ternary cathode material. The ternary positive electrode material is used as a battery positive electrode active material, common ternary positive electrode materials can be selected, and correspondingly, a ternary positive electrode precursor is a precursor material corresponding to the ternary positive electrode material.
In the embodiment of the application, the ternary positive electrode precursor particles are granular substances formed by the ternary positive electrode precursor. In some embodiments, the ternary positive electrode precursor is selected from a nickel cobalt aluminum ternary precursor or a nickel cobalt manganese ternary precursor. Wherein the nickel-cobalt-aluminum ternary precursor can be selected from NixCoyMn1-x-y(OH)2、NixCoyMn1-x-yCO3At least one of; the nickel-cobalt-aluminum ternary precursor can be selected from NixCoyAl1-x-y(OH)2、NixCoyAl1-x-yCO3At least one of (1). Wherein x is more than 0 and less than 1, and y is more than 0 and less than 1.
In some embodiments, the ternary positive electrode precursor particles have a particle size of 3 to 16 μm. Under the condition, the particle size of the ternary cathode precursor material is in a proper range, the particle size of the corresponding obtained ternary cathode material is proper, the compaction rate is high, and the ternary cathode material is not easy to break. If the particle size of the ternary positive electrode precursor particles is too small, the material synthesis difficulty is high, the material is difficult to synthesize by a common process, and the lower the compaction rate of the material is, the more fine material powder is; if the particle size of the ternary positive precursor particles is too large, the particles are easy to be too large in the process of manufacturing, and the particles are easy to be broken, so that the performance of the battery is influenced.
In the embodiment of the application, the surface of the ternary cathode precursor is combined with the metal phosphate to form a stable coating layer, so that the irreversible reaction between the ternary cathode material and the electrolyte can be responded, and the cycle performance of the battery containing the corresponding ternary cathode material can be improved. Specifically, the metal ions in the metal phosphate are at least one selected from lanthanum ions, neodymium ions, yttrium ions, praseodymium ions, niobium ions, tantalum ions, and samarium ions. The phosphate formed by the metal ions has better structural stability, and after the ternary positive electrode precursor particles are coated, the side reaction between the obtained ternary positive electrode material and the electrolyte can be reduced, and the cycle performance of the battery containing the ternary positive electrode material is improved; in addition, the metal phosphate has better coating uniformity in the precursor synthesis stage, so that the cycle performance of the battery can be improved to a greater extent.
In one possible embodiment, the phosphate coated on the surface of the ternary positive electrode precursor particle is a monometal phosphate. Illustratively, the metal phosphate is selected from at least one of lanthanum phosphate, neodymium phosphate, yttrium phosphate, praseodymium phosphate, niobium phosphate, tantalum phosphate, and samarium phosphate. The ternary positive electrode precursor particles are coated by the material, so that oxygen on the surfaces of the ternary positive electrode precursor particles can be stabilized, the stability of the ternary positive electrode precursor can be improved, the coating uniformity of the ternary positive electrode precursor particles can be improved, the side reaction between the ternary positive electrode material formed by the ternary positive electrode precursor particles and an electrolyte can be reduced, and the cycle performance of a battery containing the ternary positive electrode material can be improved. Particularly, when the metal phosphate coating the ternary positive electrode precursor particles is at least one of lanthanum phosphate, neodymium phosphate and praseodymium phosphate, the lanthanum phosphate, neodymium phosphate and praseodymium phosphate have monazite structures, so that the structural stability of the coating layer can be further improved, the ternary positive electrode precursor and a ternary positive electrode material formed by the ternary positive electrode precursor are better protected, the side reaction between the ternary positive electrode material and an electrolyte is reduced, and the cycle performance of the ternary positive electrode material is improved.
In another possible embodiment, the phosphate coated on the surface of the ternary positive electrode precursor particle is a phosphate formed by two or more metals, and the metal phosphate is, for example, neodymium lanthanum pentaphosphate, praseodymium lanthanum phosphate or praseodymium yttrium phosphate. The coating layer formed by neodymium lanthanum pentaphosphate, praseodymium lanthanum phosphate or praseodymium yttrium phosphate can also improve the coating uniformity and stability of the ternary anode precursor particles, finally reduce the side reaction between the ternary anode material formed by the ternary anode precursor particles and the electrolyte, and improve the cycle performance of the battery containing the ternary anode material.
As a preferable situation of the ternary cathode precursor material in the embodiment of the present application, the ternary cathode precursor particles are doped with metal ions, and the content of the metal ions in the ternary cathode precursor material increases in a gradient manner from inside to outside. The method has the advantages that at least one of lanthanum ions, neodymium ions, yttrium ions, praseodymium ions, niobium ions, tantalum ions and samarium ions is adopted to carry out gradient doping on the ternary anode precursor particles, so that the structural stability of the ternary anode precursor crystal can be improved, the structural stability of the ternary anode material crystal corresponding to the ternary anode precursor is further improved, the cracking risk of the ternary anode material in the circulating process is reduced, and the circulating performance of the ternary anode material is finally improved.
In some embodiments, the weight ratio of the metal phosphate to the ternary positive electrode precursor particles is from 0.05% to 5%. In this case, the coating layer formed of the metal phosphate can completely cover the surface of the ternary positive electrode precursor particle. If the coating amount of the metal phosphate is too high, impurities introduced into the positive electrode active material are excessive, resulting in a decrease in gram capacity and rate performance of the positive electrode material.
The ternary positive electrode precursor material provided by the embodiment of the application can be prepared by the following method.
In a second aspect, an embodiment of the present application provides a method for preparing a ternary cathode precursor material, including the following steps:
s01, respectively preparing phosphoric acid or a phosphate solution, a metal salt solution and a ternary anode precursor slurry, wherein metal ions in the metal salt solution are selected from at least one of lanthanum ions, neodymium ions, yttrium ions, praseodymium ions, niobium ions, tantalum ions and samarium ions, and the ternary anode precursor slurry is formed by ternary anode precursor particles.
In this step, phosphoric acid or a phosphate solution provides anions for the preparation of metal phosphates. In some embodiments, the phosphoric acid or phosphate salt solution is an aqueous solution of phosphoric acid or phosphate salt.
In some embodiments, the molar concentration of the phosphoric acid or phosphate solution is 0.5 to 3 mol/L.
The metal salt solution provides metal ions for preparing the metal phosphate, and the metal ions in the metal salt solution are selected from at least one of lanthanum ions, neodymium ions, yttrium ions, praseodymium ions, niobium ions, tantalum ions and samarium ions. These ions react with phosphoric acid or a phosphate solution in a liquid phase system to form a metal phosphate, and the metal phosphate is bonded to the surface of the ternary positive electrode precursor to form a surface coating layer. In some embodiments, the metal salt solution is an aqueous solution of a metal salt.
In some embodiments, the metal salt solution has a concentration of metal ions of 0.05 to 2 mol/L.
In the embodiment of the application, the ternary cathode precursor slurry is a slurry formed by ternary cathode precursor particles, and specifically, the ternary cathode precursor slurry is an aqueous dispersion of the ternary cathode precursor particles. The ternary positive electrode precursor particles are granular substances formed by the ternary positive electrode precursor.
In some embodiments, the ternary positive electrode precursor particles have a particle size of 3 to 16 μm. The particle size of the ternary positive electrode precursor particles is within the range, so that the phenomenon of fine powder caused by undersize particles can be reduced, the phenomenon of particle breakage caused by oversized particles can also be reduced, and after the ternary positive electrode precursor particles are converted into the ternary positive electrode material, the ternary positive electrode material can give consideration to both compaction and rate capability.
In some embodiments, the ternary cathode precursor slurry is prepared by: and adding the uncoated ternary positive precursor particles into deionized water, and uniformly stirring to obtain ternary positive precursor slurry. In some embodiments, the ternary cathode precursor slurry has a solids content of 5% to 50%. If the solid content of the ternary anode precursor slurry is too low, the reaction liquid is too thin, and the reaction efficiency of coating the metal phosphate on the surface of the ternary anode precursor is low; if the solid content of the ternary anode precursor slurry is too high, the reaction liquid is too thick, the ternary anode precursor is difficult to disperse, and the coating uniformity of the metal phosphate generated by the reaction of phosphoric acid or a phosphate solution and a metal salt is reduced.
In some embodiments, the ternary positive electrode precursor is selected from a nickel cobalt aluminum ternary precursor or a nickel cobalt manganese ternary precursor. Wherein the nickel-cobalt-aluminum ternary precursor can be selected from NixCoyMn1-x-y(OH)2、NixCoyMn1-x-yCO3At least one of; the nickel-cobalt-aluminum ternary precursor can be selected from NixCoyAl1-x-y(OH)2、NixCoyAl1-x-yCO3At least one of (1). Wherein x is more than 0 and less than 1, and y is more than 0 and less than 1.
In some embodiments, the ternary positive electrode precursor is selected from NixCoyMn1-x-y(OH)2And NixCoyMn1-x-y(OH)2The preparation method comprises the following steps:
s011, adding nickel salt, cobalt salt and manganese salt into deionized water in proportion to prepare a main metal salt solution, and providing a complexing agent and a precipitating agent.
In this step, the nickel salt, cobalt salt, and manganese salt are selected from metal salts that are soluble in deionized water. Exemplarily, the nickel salt is selected from one or more of nickel nitrate, nickel sulfate, nickel chloride and nickel acetate; the cobalt salt is selected from one or more of cobalt nitrate, cobalt sulfate, cobalt chloride and cobalt acetate; the manganese salt is selected from one or more of manganese nitrate, manganese sulfate, manganese chloride and manganese acetate.
In the embodiment of the application, nickel salt, cobalt salt and manganese salt are added into deionized water in proportion to prepare a main metal salt solution. Wherein, the adding proportion of the nickel salt, the cobalt salt and the manganese salt refers to the corresponding molar ratio of each metal element in the ternary anode precursor molecule. It should be understood that the addition ratio of the nickel salt, the cobalt salt and the manganese salt is referred to the corresponding molar ratio of each metal element in the ternary positive electrode precursor molecule, and does not mean that the addition ratio of the nickel salt, the cobalt salt and the manganese salt is strictly in accordance with the corresponding molar ratio of each metal element in the ternary positive electrode precursor molecule, and the ratio can be properly adjusted on the basis of the corresponding molar ratio of each metal element in the ternary positive electrode precursor molecule.
In some embodiments, the molar concentrations of the nickel salt, the cobalt salt and the manganese salt are respectively 0.8-2.5 mol/L. The nickel salt, the cobalt salt and the manganese salt have good solubility in the concentration range, and meanwhile, a formed reaction system has proper viscosity, so that the reaction is facilitated.
In the embodiment of the application, the complexing agent is used for complexing metal ions in nickel salt, cobalt salt and manganese salt. In some embodiments, the complexing agent is selected from at least one of ammonia, citric acid, EDTA, ammonium carbonate. The complexing agent can form complex metal ions with nickel ions, cobalt ions and manganese ions. During the reaction process, the complexing metal ions slowly release the metal ions, and the reaction speed between the complexing metal ions and the precipitating agent is controlled, so that a spherical ternary positive electrode precursor is finally formed. If no complexing agent is added, the reaction between the nickel salt, cobalt salt, manganese salt and the precipitant is too violent, and finally a flaky ternary compound may be formed. In some embodiments, the complexing agent is dissolved in deionized water to provide a complexing agent solution. In some embodiments, the concentration of the complexing agent solution is 5-18 mol/L. The concentration of the complexing agent is in the range, the solid content of the obtained reaction system is in a proper range, and the ternary positive electrode precursor with proper tap density and specific surface area can be obtained. In the embodiment of the application, the precipitator is used for promoting the nickel salt, the cobalt salt and the manganese salt to be converted into the metal compound precipitate and converted into the ternary positive electrode precursor. In some embodiments, the precipitating agent is selected from at least one of sodium hydroxide, potassium hydroxide. The precipitant can convert nickel salt, cobalt salt and manganese salt into nickel hydroxide, cobalt hydroxide and manganese hydroxide precipitate, and convert the substances into NixCoyMn1-x-y(OH)2. In some embodiments, the precipitant solution has a concentration of 5 to 15 mol/L. If the concentration of the complexing agent is too high, the growth speed of the particles is too high, and the particle size of the ternary anode precursor is not easy to control.
S012. willFeeding a main metal salt solution, a complexing agent and a precipitator into a reaction kettle, heating the mixture in an inert atmosphere to perform coprecipitation chemical reaction to prepare a ternary anode precursor NixCoyMn1-x-y(OH)2。
In the step, a main metal salt solution, a complexing agent and a precipitator are fed into a reaction kettle, and the temperature is controlled to enable nickel salt, cobalt salt and manganese salt in the main metal salt solution to have a coprecipitation chemical reaction under the action of the complexing agent and the precipitator, so that a ternary anode precursor Ni is generatedxCoyMn1-x-y(OH)2。
In some embodiments, the heating temperature for the co-precipitation chemical reaction is 45-85 ℃. The heating temperature is in the range, so that the reaction speed of the coprecipitation chemical reaction is in a proper range, and the particle size of the ternary cathode precursor is favorably controlled. If the heating temperature is too high, the reaction speed of the coprecipitation chemical reaction is too high, and the generated large-particle ternary positive electrode precursor is easy to generate ball cracks.
It should be noted that in the examples of the present application, the primary metal salt solution, the complexing agent and the precipitant are fed into the reaction kettle for reaction, and the reaction is performed in an inert atmosphere, so as to prevent other side reactions from occurring due to air introduced into the reaction system. Wherein the inert atmosphere comprises one of a nitrogen atmosphere and an inert gas atmosphere. Illustratively, the inert gas is helium, neon, argon, krypton, or xenon.
In some embodiments, the ternary positive precursor Ni is generated by continuously adding a main metal salt solution, a complexing agent and a precipitating agent into a reaction kettlexCoyMn1-x-y(OH)2. In this implementation situation, the reaction process can be monitored and adjusted by testing the pH, temperature or slurry particle size in the reaction kettle, and the feeding is stopped after the particle size of the synthesized ternary cathode precursor particles meets the requirements. In some embodiments, when the complexing agent is ammonia, the reaction progress can also be monitored by detecting the ammonia concentration in the reaction system. Illustratively, the reactor is tested for ammonia concentration, pH, temperature, and slurry particle size per hour, the pH is controlled as required, and the feed is stopped after the particle size requirement is met.
In some embodiments, during the heating for the coprecipitation chemical reaction, the slurry in the reaction kettle is tested for particle size and NixCoyMn1-x-y(OH)2The particle size of the slurry is 3-16 mu m, and then the feeding is stopped. Control of NixCoyMn1-x-y(OH)2The particle size of the ternary positive electrode precursor particles is 3-16 mu m, so that the phenomenon of fine powder caused by undersize particles can be reduced, the phenomenon of particle breakage caused by oversized particles can also be reduced, and after the ternary positive electrode precursor particles are converted into the ternary positive electrode material, the ternary positive electrode material can give consideration to both compaction and rate capability.
Feeding a main metal salt solution, a complexing agent and a precipitator into a reaction kettle, heating the mixture to perform coprecipitation chemical reaction under inert atmosphere to prepare a ternary anode precursor NixCoyMn1-x-y(OH)2And after the reaction is finished, the materials in the reaction kettle are aged, filtered, washed and dried to obtain uncoated ternary positive precursor particles.
Ternary positive electrode precursor Ni prepared by the methodxCoyMn1-x-y(OH)2And the particle size uniformity is better.
And S02, mixing and reacting phosphoric acid or a phosphate solution, a metal salt solution and the ternary anode precursor slurry, and generating metal phosphate on the surface of the ternary anode precursor particles in situ to obtain the ternary anode precursor material coated by the metal phosphate.
In the step, after phosphoric acid or a phosphate solution, a metal salt solution and the ternary positive electrode precursor slurry are mixed, phosphate ions in the phosphoric acid or the phosphate solution react with metal ions in the metal salt solution to generate a metal phosphate. In addition, the generated metal phosphate is bonded to the surface of the ternary positive electrode precursor to form a coating layer of the ternary positive electrode precursor. Different from direct surface coating of the ternary cathode material, the embodiment of the application coats the metal phosphate in situ on the surface of the ternary cathode precursor through chemical coprecipitation, so that the coating uniformity of the metal phosphate on the ternary cathode precursor can be improved, and the cycle performance of the ternary cathode material corresponding to the ternary cathode precursor is improved to a greater extent. In addition, when the ternary cathode precursor is converted into the corresponding ternary cathode material, the metal ions in the metal phosphate on the surface of the ternary cathode precursor can be driven to permeate into the ternary cathode precursor particles through high-temperature calcination, so that the metal doping of the ternary cathode material is realized, the crystal stability of the ternary cathode material is improved, and the cycle performance of the ternary cathode material is further improved.
In the embodiment of the application, phosphoric acid or a phosphate solution, a metal salt solution and a ternary cathode precursor slurry are mixed, the adding sequence is not strictly limited, and phosphoric acid or a phosphate solution and a metal salt solution which are prepared in advance can be added into the ternary cathode precursor slurry; or mixing phosphoric acid or phosphate solution, metal salt solution and ternary anode precursor slurry together; not limited thereto.
In some embodiments, the ternary cathode precursor slurry, the complexing agent and the precipitant are fed into the reaction kettle according to the molar concentration of the ternary cathode precursor slurry being 0.8-2.5 mol/L, the molar concentration of the phosphoric acid or phosphate solution being 0.5-3 mol/L, and the concentration of the metal ions in the metal salt solution being 0.05-2 mol/L. In this case, the phosphoric acid or the phosphate and the metal ions in the reaction system have appropriate concentrations, and the reaction system has appropriate viscosity, so that the phosphoric acid or the phosphate and the metal ions can react in situ and are combined on the surface of the ternary positive electrode precursor to form a uniformly-coated coating layer.
In some embodiments, the temperature for mixing and reacting the phosphoric acid or the phosphate solution, the metal salt solution and the ternary cathode precursor slurry is 20-80 ℃. Under the temperature condition, phosphoric acid or phosphate reacts with metal ions in a reaction system, and the phosphoric acid or phosphate is combined with the surface of the ternary positive electrode precursor to form a coating layer.
According to the preparation method of the ternary cathode precursor material, the metal phosphate coating layer is generated on the surface of the ternary cathode precursor through the solution coprecipitation method, in-situ coating of ternary cathode precursor particles can be achieved, and coating uniformity and structural stability are improved. After the ternary anode precursor material is converted into the ternary anode material, the side reaction of the ternary anode material and the electrolyte can be reduced in the circulation process, and the circulation performance of the battery is improved. In addition, in the process of calcining the ternary cathode precursor coated in the manner after the lithium source is introduced, metal ions in the coating layer permeate into the ternary cathode material, so that the metal doping of the ternary cathode material is realized, and the cycle performance of the ternary cathode material is improved.
In a third aspect, an embodiment of the present application provides a method for preparing a ternary cathode material, where a ternary cathode precursor material prepared by the preparation method provided in the first aspect of the embodiment of the present application is mixed with a lithium source and then calcined to obtain the ternary cathode material.
According to the preparation method of the ternary cathode material, the ternary cathode precursor with the surface coated with the metal phosphate is used as the raw material, and the ternary cathode material obtained after lithium is prepared has good coating uniformity, so that the rate capability and the cycle performance of a battery containing the ternary cathode material can be improved. In addition, in the calcining treatment process of lithium preparation, metal ions in the coating layer permeate into the ternary cathode material, so that the structural stability of the crystal is improved, and the rate capability and the cycle performance of the battery containing the ternary cathode material are further improved.
In the examples of the present application, the ternary positive electrode precursor material was mixed with a lithium source with reference to the stoichiometric ratio in the ternary positive electrode material.
In the embodiment of the application, the ternary cathode precursor material and a lithium source are calcined to promote lithium to be rapidly diffused into the ternary cathode precursor crystal, so that the ternary cathode material is prepared. In some embodiments, the temperature of the calcination process is from 700 ℃ to 1150 ℃. In the temperature range, the high-temperature calcination can drive metal ions in metal phosphate on the surface of the ternary positive electrode precursor to permeate into the ternary positive electrode precursor particles, so that metal doping of the ternary positive electrode material is realized, the crystal stability of the ternary positive electrode material is improved, and the cycle performance of the ternary positive electrode material is further improved.
In a fourth aspect, an embodiment of the present application provides a ternary cathode material, which is prepared by the preparation method provided in the first aspect of the embodiment of the present application.
The ternary cathode material provided by the embodiment of the application is prepared by the method, so that a coating layer formed on the surface of the ternary cathode material has better coating uniformity, and the cycle performance of a battery containing the ternary cathode material can be improved. In addition, due to the ternary cathode material prepared by the method, metal ions in the coating layer permeate into the ternary cathode material, so that the structural stability of the ternary cathode material crystal can be improved, and the cycle performance of a battery containing the ternary cathode material is further improved.
In a fifth aspect, embodiments of the present application provide a lithium battery including the ternary cathode material as provided in the fourth aspect of embodiments of the present application.
The lithium battery provided by the embodiment of the application contains the ternary cathode material, so that the rate capability and the cycle performance of the battery can be effectively improved.
The following description will be given with reference to specific examples.
Example 1
A preparation method of a lithium ion battery comprises the following steps:
according to Ni0.5Co0.2Mn0.3(OH)2Adding nickel chloride, cobalt chloride and manganese chloride into deionized water according to the molar ratio of nickel, cobalt and manganese, and preparing a main metal salt solution with the metal ion concentration of 2.1 mol/L; preparing an ammonia water solution with the concentration of 15mol/L and a sodium hydroxide water solution with the concentration of 12 mol/L;
adding a main metal salt solution, an ammonia water solution and a sodium hydroxide solution into a reaction kettle according to a stoichiometric proportion through a metering pump, carrying out coprecipitation chemical reaction, testing the pH, the temperature, the ammonia concentration and the particle size of a reaction system every hour, controlling the pH of the reaction system to be 10.95, the temperature to be 55 ℃ and the ammonia concentration to be 6.5-7 g/L, stopping feeding when the particle size of ternary positive electrode precursor particles in the reaction system reaches 8.5um, and continuously stirring and aging in the reaction kettle for 10 hours;
filtering, washing and drying the materials in the reaction kettle to obtain uncoated ternary anode precursor materials,preparing a sodium phosphate solution with the concentration of 0.5mol/L and a neodymium sulfate solution with the concentration of 0.5 mol/L; weighing uncoated ternary positive electrode precursor materials, adding deionized water, and stirring to prepare ternary positive electrode precursor slurry with the solid content of 15%; adding a sodium phosphate solution and a neodymium sulfate solution into the ternary anode precursor slurry to obtain a coated ternary anode precursor material Ni0.5Co0.2Mn0.3(OH)2·0.002NdPO4;
Mixing Ni0.5Co0.2Mn0.3(OH)2·0.002NdPO4Preparing lithium, and calcining at 950 ℃ to obtain the ternary cathode material LiNi0.5Co0.2Mn0.3O2·0.002NdPO4. And coating the slurry of the ternary cathode material on an aluminum foil, baking and then die-cutting to obtain the cathode plate. And preparing the diaphragm, the positive plate and the negative plate into the button type lithium ion battery.
Example 2
A preparation method of a lithium ion battery comprises the following steps:
according to Ni0.6Co0.2Mn0.2(OH)2Adding nickel nitrate, cobalt nitrate and manganese nitrate into deionized water according to the molar ratio of nickel, cobalt and manganese, and preparing a main metal salt solution with the metal ion concentration of 2.0 mol/L; preparing an ammonia water solution with the concentration of 13mol/L and a sodium hydroxide water solution with the concentration of 10 mol/L;
adding a main metal salt solution, an ammonia water solution and a sodium hydroxide solution into a reaction kettle according to a stoichiometric ratio through a metering pump, carrying out coprecipitation chemical reaction, testing the pH, the temperature, the ammonia concentration and the particle size of a reaction system every hour, controlling the pH of the reaction system to be 10.85, the temperature to be 58 ℃ and the ammonia concentration to be 7.5-8 g/L, stopping feeding when the particle size of ternary positive electrode precursor particles in the reaction system reaches 9.5um, and continuously stirring and aging in the reaction kettle for 8 hours;
filtering, washing and drying materials in the reaction kettle to obtain uncoated ternary anode precursor materials, and preparing ammonium dihydrogen phosphate solution with the concentration of 0.8mol/L and neodymium nitrate solution with the concentration of 0.8 mol/L; will be uncoated ternaryWeighing the anode precursor material, adding deionized water, and stirring to prepare ternary anode precursor slurry with the solid content of 10%; adding ammonium dihydrogen phosphate solution and neodymium nitrate solution into the ternary anode precursor slurry to obtain a coated ternary anode precursor material Ni0.6Co0.2Mn0.2(OH)2·0.002NdPO4;
Mixing Ni0.6Co0.2Mn0.2(OH)2·0.002NdPO4Preparing lithium, and calcining at 900 ℃ to obtain the ternary cathode material LiNi0.6Co0.2Mn0.2O2·0.002NdPO4. And coating the slurry of the ternary cathode material on an aluminum foil, baking and then die-cutting to obtain the cathode plate. And preparing the diaphragm, the positive plate and the negative plate into the button type lithium ion battery.
Example 3
A preparation method of a lithium ion battery comprises the following steps:
according to Ni0.7Co0.1Mn0.2(OH)2Adding nickel sulfate, cobalt sulfate and manganese sulfate into deionized water according to the molar ratio of nickel, cobalt and manganese, and preparing a main metal salt solution with the metal ion concentration of 1.8 mol/L; preparing an ammonia water solution with the concentration of 12mol/L and a sodium hydroxide solution with the concentration of 8 mol/L;
adding a main metal salt solution, an ammonia water solution and a sodium hydroxide solution into a reaction kettle according to a stoichiometric ratio through a metering pump, carrying out coprecipitation chemical reaction, testing the pH, the temperature, the ammonia concentration and the particle size of a reaction system every hour, controlling the pH of the reaction system to be 11.0, the temperature to be 60 ℃ and the ammonia concentration to be 8.5-9 g/L, stopping feeding when the particle size of ternary positive electrode precursor particles in the reaction system reaches 10.0um, and continuously stirring and aging in the reaction kettle for 8 hours;
filtering, washing and drying materials in the reaction kettle to obtain uncoated ternary anode precursor materials, and preparing a phosphoric acid solution with the concentration of 0.8mol/L and a neodymium chloride solution with the concentration of 0.8 mol/L; weighing uncoated ternary positive electrode precursor material, adding deionized water, stirring, and preparing ternary positive electrode precursor with solid content of 20%Sizing agent; adding phosphoric acid solution and neodymium chloride solution into the ternary anode precursor slurry to obtain the coated ternary anode precursor material Ni0.7Co0.1Mn0.2(OH)2·0.004NdPO4;
Mixing Ni0.7Co0.1Mn0.2(OH)2·0.004NdPO4Preparing lithium, and calcining at 860 ℃ to obtain the ternary cathode material LiNi0.7Co0.1Mn0.2O2·0.004NdPO4. And coating the slurry of the ternary cathode material on an aluminum foil, baking and then die-cutting to obtain the cathode plate. And preparing the diaphragm, the positive plate and the negative plate into the button type lithium ion battery.
Example 4
A preparation method of a lithium ion battery comprises the following steps:
according to Ni0.8Co0.1Mn0.1(OH)2Adding nickel acetate, cobalt acetate and manganese acetate into deionized water according to the molar ratio of nickel, cobalt and manganese, and preparing a main metal salt solution with the metal ion concentration of 1.6 mol/L; preparing an ammonia water solution with the concentration of 10mol/L and a sodium hydroxide solution with the concentration of 8 mol/L;
adding a main metal salt solution, an ammonia water solution and a sodium hydroxide solution into a reaction kettle according to a stoichiometric ratio through a metering pump, carrying out coprecipitation chemical reaction, testing the pH, the temperature, the ammonia concentration and the particle size of a reaction system every hour, controlling the pH of the reaction system to be 11.5, the temperature to be 60 ℃ and the ammonia concentration to be 9.5-10 g/L, stopping feeding when the particle size of ternary positive electrode precursor particles in the reaction system reaches 10.5um, and continuously stirring and aging in the reaction kettle for 6 hours;
filtering, washing and drying materials in the reaction kettle to obtain uncoated ternary anode precursor materials, and preparing a phosphoric acid solution with the concentration of 1mol/L and a neodymium nitrate solution with the concentration of 1 mol/L; weighing uncoated ternary positive electrode precursor materials, adding deionized water, and stirring to prepare ternary positive electrode precursor slurry with the solid content of 25%; adding phosphoric acid solution and neodymium chloride solution into the ternary anode precursor slurry to obtain a coated ternary anode precursorNi material0.8Co0.1Mn0.1(OH)2·0.008NdPO4;
Mixing Ni0.8Co0.1Mn0.1(OH)2·0.008NdPO4Preparing lithium, and calcining at 780 ℃ at high temperature to obtain the ternary cathode material LiNi0.8Co0.1Mn0.1O2·0.008NdPO4. And coating the slurry of the ternary cathode material on an aluminum foil, baking and then die-cutting to obtain the cathode plate. And preparing the diaphragm, the positive plate and the negative plate into the button type lithium ion battery.
Example 5
A preparation method of a lithium ion battery comprises the following steps:
preparing a sodium phosphate solution with the concentration of 1mol/L and a neodymium sulfate solution with the concentration of 1 mol/L; uncoated ternary positive precursor material Ni0.5Co0.2Mn0.3CO3Weighing, adding deionized water, and stirring to prepare ternary positive precursor slurry with solid content of 15%; adding a sodium phosphate solution and a neodymium sulfate solution into the ternary anode precursor slurry to obtain a monazite-coated ternary anode precursor material Ni0.5Co0.2Mn0.3CO3·0.004NdPO4;
Mixing Ni0.5Co0.2Mn0.3CO3·0.004NdPO4Preparing lithium, and calcining at 950 ℃ to obtain the ternary cathode material LiNi0.5Co0.2Mn0.3O2·0.004NdPO4. And coating the slurry of the ternary cathode material on an aluminum foil, baking and then die-cutting to obtain the cathode plate. And preparing the diaphragm, the positive plate and the negative plate into the button type lithium ion battery.
Example 6
A preparation method of a lithium ion battery comprises the following steps:
preparing a sodium phosphate solution with the concentration of 1.2mol/L, and a yttrium sulfate solution and a praseodymium sulfate solution with the concentration of 0.6 mol/L; uncoated ternary positive precursor material Ni0.8Co0.15Al0.05(OH)2WeighingThen adding deionized water, and stirring to prepare ternary positive electrode precursor slurry with the solid content of 15%; adding a sodium phosphate solution, yttrium sulfate and praseodymium sulfate solution into the ternary positive precursor slurry to obtain a ternary positive precursor material Ni0.8Co0.15Al0.05(OH)2·0.004YPO4·0.004PrPO4;;
Mixing Ni0.8Co0.15Al0.05(OH)2·0.004YPO4·0.004PrPO4Preparing lithium, and calcining at 950 ℃ to obtain the ternary cathode material LiNi0.8Co0.15Al0.05O2·0.004YPO4·0.004PrPO4. And coating the slurry of the ternary cathode material on an aluminum foil, baking and then die-cutting to obtain the cathode plate. And preparing the diaphragm, the positive plate and the negative plate into the button type lithium ion battery.
Comparative example 1
A preparation method of a lithium ion battery comprises the following steps:
according to Ni0.5Co0.2Mn0.3(OH)2Adding nickel sulfate, cobalt sulfate and manganese sulfate into deionized water according to the molar ratio of nickel to cobalt to manganese, wherein the ratio of nickel to cobalt to manganese is 5:2:3, and preparing a salt solution with the metal ion concentration of 2 mol/L; preparing an ammonia water solution with the concentration of 12mol/L and a sodium hydroxide solution with the concentration of 10 mol/L;
adding a nickel-cobalt-manganese sulfate solution, an ammonia water solution and a sodium hydroxide solution into a reaction kettle according to a stoichiometric ratio through a metering pump, carrying out coprecipitation synthesis reaction, testing the pH, the temperature, the ammonia concentration and the particle size in a reaction system every hour, controlling the pH of the reaction system to be 10.6, the temperature to be 60 ℃ and the ammonia concentration to be 6-7 g/L, stopping feeding when the particle size in slurry reaches 8.5 microns, and continuing stirring and aging for 8 hours;
filtering, washing and drying the materials in the reaction kettle to obtain the required ternary anode precursor material Ni0.5Co0.2Mn0.3(OH)2;
Mixing Ni0.5Co0.2Mn0.3(OH)2To carry out lithium preparationCalcining at 950 ℃ to obtain the ternary cathode material LiNi0.5Co0.2Mn0.3O2. And coating the slurry of the ternary cathode material on an aluminum foil, baking and then die-cutting to obtain the cathode plate. And preparing the diaphragm, the positive plate and the negative plate into the button type lithium ion battery.
Comparative example 2
A preparation method of a lithium ion battery comprises the following steps:
according to Ni0.5Co0.2Mn0.3(OH)2Adding nickel sulfate, cobalt sulfate and manganese sulfate into deionized water according to the molar ratio of nickel to cobalt to manganese, wherein the ratio of nickel to cobalt to manganese is 5:2:3, and preparing a salt solution with the metal ion concentration of 2 mol/L; preparing an ammonia water solution with the concentration of 12mol/L and a sodium hydroxide solution with the concentration of 10 mol/L;
adding a nickel-cobalt-manganese sulfate solution, an ammonia water solution and a sodium hydroxide solution into a reaction kettle according to a stoichiometric ratio through a metering pump, carrying out coprecipitation synthesis reaction, testing the pH, the temperature, the ammonia concentration and the particle size in a reaction system every hour, controlling the pH of the reaction system to be 10.6, the temperature to be 60 ℃ and the ammonia concentration to be 6-7 g/L, stopping feeding when the particle size in slurry reaches 8.5 microns, and continuing stirring and aging for 8 hours;
filtering, washing and drying the materials in the reaction kettle to obtain the required ternary anode precursor material Ni0.5Co0.2Mn0.3(OH)2;
Mixing Ni0.5Co0.2Mn0.3(OH)2Preparing lithium, calcining at 950 deg.C to obtain Li Ni0.5Co0.2Mn0.3O2. Taking neodymium phosphate solid powder and Li Ni according to proportion0.5Co0.2Mn0.3O2Evenly mixing, and calcining at 550 ℃ to obtain the neodymium phosphate coated ternary cathode material LiNi0.5Co0.2Mn0.3O2·0.002NdPO4。
And coating the slurry of the ternary cathode material on an aluminum foil, baking and then die-cutting to obtain the cathode plate. And preparing the diaphragm, the positive plate and the negative plate into the button type lithium ion battery.
The button lithium ion battery correspondingly prepared from the ternary positive electrode precursors obtained in the embodiments 1-6 and the comparative examples 1-2 is subjected to performance detection, and the detection method comprises the following steps:
the first efficiency and normal temperature cycle performance test is carried out under the condition of 3-4.3V, the first discharge gram capacity is tested in the 0.1C/0.1C charge-discharge test, the cycle performance is the capacity retention rate result of 100 cycles under the 1C/1C charge-discharge condition, and the result is shown in Table 1:
TABLE 1
As can be seen from table 1, in the embodiment of the application, the ternary cathode precursor is coated, so that the cycle performance of the ternary cathode material corresponding to the obtained ternary cathode precursor can be effectively improved.
The present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed.