CN116387508A - Aluminum-boron co-doped ternary positive electrode material and preparation method and application thereof - Google Patents

Aluminum-boron co-doped ternary positive electrode material and preparation method and application thereof Download PDF

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CN116387508A
CN116387508A CN202310381891.9A CN202310381891A CN116387508A CN 116387508 A CN116387508 A CN 116387508A CN 202310381891 A CN202310381891 A CN 202310381891A CN 116387508 A CN116387508 A CN 116387508A
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boron
aluminum
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朱永明
宫相硕
高鹏
王桢
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Harbin Institute of Technology Weihai
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E60/10—Energy storage using batteries

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Abstract

The invention provides an aluminum-boron co-doped ternary positive electrode material, which is prepared from the following raw materials of a precursor, a lithium source, an aluminum source and a boron source; the chemical formula of the ternary positive electrode material is Li (Ni x Co y Mn z ) 1‑b‑c Al b B c O 2 Wherein x is more than or equal to 0.7 and less than or equal to 0.98,0.01, y is more than or equal to 0.1, z is more than or equal to 0.01 and less than or equal to 0.2, and x+y+z=1; b is more than 0 and less than or equal to 0.015,0, c is more than or equal to 0.015, and b+c is more than 0 and less than or equal to 0.03. The invention is characterized in that proper amount of Al and B are doped in the positive electrode material, and specific Al/B doping sequence and doping amount are limited, and the modified positive electrode material has excellent electrochemical performance, thus effectively improving the specific discharge capacity and cycle of the batteryRing performance and rate performance. Particularly in the high voltage range of 2.75-4.5V, has excellent cycle performance and rate performance. The process is simple and easy to control, has high yield ratio, and is favorable for popularization and application of industrial mass production.

Description

Aluminum-boron co-doped ternary positive electrode material and preparation method and application thereof
Technical Field
The invention relates to the technical field of battery anode materials, in particular to an aluminum-boron co-doped ternary anode material, and a preparation method and application thereof.
Background
Since the advent of Lithium Ion Batteries (LIBs) in the nineties of the 20 th century, lithium ion batteries have attracted considerable attention due to their ultra-high energy density and excellent long-cycle stability, particularly in electronic devices, electric Vehicles (EV) and energy storage systems. The lithium ion battery is used as an important power source of the electric automobile, and the most important research direction is to increase specific energy density, increase the cycle performance and safety stability of the lithium ion battery and reduce the cost. Thus, there is a current urgent need to develop efficient, sustainable, low cost batteries. In lithium ion batteries, the most important component determining the performance of the battery is the positive electrode material. Among the numerous positive electrode materials, nickel cobalt manganese/lithium aluminate ternary positive electrode materials (LiNi x Co y Mn 1–x–y O 2 /LiNi x Co y Al 1–x–y O 2 Abbreviated as NCM/NCA), in particular high nickel NCM/NCA (0.5. Ltoreq.x<1) Is expected to be thick. In such materials, the specific discharge capacity increases with the nickel content, but the cycle performance decreases. The increase of nickel content brings about a great increase of capacity, but brings about a series of new problems, which can be mainly divided into surface problems and bulk problems, such as surface residual alkali, transition metal dissolution, cation mixing and discharging, and the like.
In order to improve the electrochemical performance of the NCM ternary material and meet the market demand, the NCM ternary material is modified mainly by the following means: and (1) doping modification. Introducing transition metal ions and other non-metal ions into the crystal lattice of the NCM ternary material to improve the electronic conductivity and the ionic conductivity of the material, so as to further enhance the stability of the ternary material structure; and (2) coating modification. Coating a thinner metal oxide layer on the surface of the material to reduce side reactions, namely, in a high state of charge (SOC), the generated special coating protective layer reduces the direct contact area of the material and electrolyte, prevents the electrolyte from corroding the material, reduces the side reactions such as oxygen release and the like, prolongs the cycle life of the material and improves the stability of the material; and (3) structural design. Structural design is carried out on the material, element distribution in the material is changed, and stability and safety in the battery circulation process can be effectively improved.
Coating has remarkable effect on solving the surface problem of the material, but has very limited effect on a crystal structure, and a bulk phase structure is also a key point affecting the performance of the material, so that the performance of the material needs to be further improved by doping modification. Doping a particular single element can lead to significant improvements in electrochemical performance, particularly when two or more elements are co-doped, interactions between the elements can occur, leading to a leap in performance. When the doping order or doping amount of two or more elements is changed, the effect of the doped elements on the material is also different.
Chinese patent CN110112403A discloses a high specific capacity nickel cobalt lithium manganate positive electrode material and a preparation method thereof, wherein the material comprises a precursor, an aluminum doping body, a boron doping body, a coating body and a lithium source, and the structural stability of the nickel cobalt lithium manganate in the circulation process is effectively improved by coating a layer of silicon dioxide on the surface of the material and doping boron element and aluminum element into the bulk phase of the material. However, the doped elements are more, so that mutual interference is easy to form, and the performance of the material is influenced.
In summary, how to prepare a ternary positive electrode material with excellent electrochemical performance, and the preparation process is simple and convenient to operate, and the process is stable and easy to control is still the focus of current research.
Disclosure of Invention
In order to solve the problems, the invention provides an aluminum-boron co-doped ternary positive electrode material, wherein the preparation raw materials of the ternary positive electrode material comprise a precursor, a lithium source, an aluminum source and a boron source; the chemical formula of the ternary positive electrode material is Li (Ni x Co y Mn z ) 1-b-c Al b B c O 2 Wherein x is more than or equal to 0.7 and less than or equal to 0.98,0.01, y is more than or equal to 0.1, z is more than or equal to 0.01 and less than or equal to 0.2, and x+y+z=1; b is more than 0 and less than or equal to 0.015,0, c is more than or equal to 0.015, and b+c is more than 0 and less than or equal to 0.03. Examples of x include 0.75, 0.8, 0.85, 0.9, 0.95, and examples of y include 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09Examples of z include 0.05, 0.1, and 0.15, examples of b include 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.011, 0.012, 0.013, 0.014, and 0.015, examples of c include 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.011, 0.012, 0.013, 0.014, and 0.015, but the present invention is not limited to the above values, and other values not listed in the above numerical range are equally applicable. More preferably, the ratio of b to 0.008,0.001 is greater than 0.001 and less than or equal to c is greater than or equal to 0.008, and the ratio of b+c is greater than or equal to 0.002 and less than or equal to 0.016.
The following preferred technical solutions are used as the present invention, but not as limitations on the technical solutions provided by the present invention, and the technical objects and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solutions.
The second aspect of the invention provides a preparation method of the ternary positive electrode material, which comprises the following steps:
step S1: preparing a precursor: weighing a nickel source, a cobalt source and a manganese source, mixing to prepare a salt solution, adding the salt solution, a precipitator and a complexing agent into a reactor, reacting at 40-60 ℃ to obtain a solid-liquid mixture, filtering the solid-liquid mixture, and drying to obtain a precursor;
step S2: mixing the precursor with a lithium source, adding an aluminum source, and performing first calcination to obtain a sintered product A; adding a boron source, performing secondary calcination to obtain a sintered product B, and grinding the sintered product B to powder to obtain the ternary anode material.
Preferably, the chemical formula of the precursor is Ni x Co y Mn z (OH) 2 Wherein x is more than or equal to 0.7 and less than or equal to 0.98,0.01, y is more than or equal to 0.1, z is more than or equal to 0.01 and less than or equal to 0.2, and x+y+z=1. Examples of x include 0.75, 0.8, 0.85, 0.9, and 0.95, examples of y include 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, and 0.09, examples of z include 0.05, 0.1, and 0.15, but the present invention is not limited to the above-mentioned values, and other non-mentioned values in the above-mentioned numerical ranges are applicable. More preferably, the 0.8.ltoreq.x.ltoreq. 0.95,0.02.ltoreq.y.ltoreq. 0.06,0.02.ltoreq.z.ltoreq.0.15, and x+y+z=1.
Ni is used in the present invention x Co y Mn z (OH) 2 And as a precursor, the high-nickel low-cobalt ternary cathode material is adopted, so that the specific capacity of the battery is improved, the content of cobalt in the battery is reduced, and the material cost of the battery is reduced.
Preferably, in the step S1, the nickel source is NiSO 4 ·6H 2 O、Ni(CH 3 COO) 2 ·4H 2 One of O; the cobalt source is CoSO 4 ·7H 2 O、Co(CH 3 COO) 2 ·4H 2 One of O; the manganese source is MnSO 4 ·H 2 O、MnCO 3 、Co(CH 3 COO) 2 ·4H 2 One of O.
Preferably, in step S1, the molar ratio of nickel in the nickel source, cobalt in the cobalt source, and manganese in the manganese source is 7-9.8:0.1-1:0.1-2. More preferably, the molar ratio of nickel, cobalt and manganese is 8-9.5:0.1-0.6:0.1-1.5.
Preferably, in the step S1, the precipitant is 0.5-10 mol/L NaOH solution; the complexing agent is 0.05-3 mol/L ammonia water solution.
More preferably, the concentration of the NaOH solution is 1-5 mol/L, and the concentration of the ammonia solution is 0.1-2 mol/L.
Preferably, in the step S1, the concentration ratio of the salt solution, the precipitant and the complexing agent is 1:0.8-1.2:0.02-0.05. There may be mentioned 1:0.8:0.02, 1:0.9:0.03, 1:1:0.04, 1:1.1:0.05, but is not limited to the recited values, and other non-recited values within this range are equally applicable. More preferably, the concentration ratio of the salt solution, the precipitant and the complexing agent is 1:1:0.3.
the proportion of the salt solution, the precipitant and the complexing agent in the reaction is controlled, the adding rate is controlled, the pH value in the reaction is controlled to be 11-12, and the stirring is matched at the same time, so that the efficient and stable performance of the reaction is ensured, and the prepared precursor has uniform particle size and stable performance and is more easy to be used as a matrix of the ternary anode material doped with aluminum and boron. The inventors found in experiments that, although the reaction time can be shortened by accelerating the feeding amount, if the feeding rate is too fast, the reaction is not uniform, the particle size of the prepared precursor is not uniform, and the further aluminum-boron doping effect is affected, so that the battery performance of the precursor serving as a positive electrode material is affected. Too large or too small pH can affect the growth reaction of the precursor, too small pH or too slow reaction, but too large pH can also cause the problems of small particle size of the precursor, uneven reaction and the like, and the electrochemical performance of the material is reduced due to charge and discharge in use.
Preferably, the pH at the time of the reaction in the step S1 is 11-12.
Preferably, in the step S1, the adding rate of the salt solution and the precipitant is 0.1-3 ml/min, and the adding rate of the complexing agent is 0.01-2 ml/min.
Preferably, in the step S1, stirring is performed while feeding, and the stirring speed is 300-600 rpm.
The inventor discovers that the too high or too low stirring speed can cause poor performance of the prepared precursor and affect the battery performance of the prepared positive electrode material. The inventor analyzes that the shearing can be generated due to the excessively high stirring speed, so that the uneven particle size of the precursor can influence the performance of the precursor, and the instability of a machine can be caused, so that the production and the use of a product are influenced. While too low a stirring rate may result in too high a local concentration of the reaction materials, reducing the reliability of the material.
Preferably, in the step S1, the drying temperature is 100-130 ℃ and the duration is 6-10 hours.
Further preferably, in step S1, the solid-liquid mixture is dried and then sieved through a 300 mesh sieve to obtain a precursor. And the impurity is removed by sieving treatment, so that the uniformity of the precursor is improved.
Preferably, in step S2, the lithium source is lioh.h 2 O or Li 2 CO 3 One or both of them.
More preferably, the molar ratio of the precursor to the lithium source is 1:1.05 to 1.08. The content of the lithium source is higher in the present invention due to lithium loss during calcination.
Preferably, in step S2, the aluminum in the aluminum source is 0-1.5% and not equal to 0 of the precursor molar amount; boron in the boron source is 0-1.5% of the precursor molar amount and is not equal to 0. Examples of the above-mentioned values include 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, and 1.5%, but are not limited to the above-mentioned values, and other values not mentioned in the above-mentioned numerical ranges are equally applicable. Preferably, the aluminum in the aluminum source is 0.1% -0.8% of the molar amount of the precursor; boron in the boron source is 0.1% -0.8% of the precursor molar quantity. More preferably, the aluminum in the aluminum source is 0.5% of the precursor molar amount; boron in the boron source is 0.5% of the precursor molar amount.
According to the invention, by doping a proper amount of Al and B into the positive electrode material, the prepared positive electrode material has excellent electrochemical performance, the specific discharge capacity of the battery is effectively improved, and the cycle performance and the multiplying power performance of the battery are improved. The inventor analyzes that, due to the doping of aluminum and boron, primary particles which are radially arranged are generated inside the material, and the primary particles are radially arranged, so that the whole positive electrode particles are uniformly contracted, thereby eliminating local stress concentration and minimizing microcracks. Therefore, the problems that in the battery circulation process, the longitudinal stress in the spherical particles is too large and the particles are easy to damage are solved, and the circulation performance and the multiplying power performance of the material are effectively improved. However, if the content of Al and B is too high, the battery performance of the material may be affected, and the layered structure of the matrix material may be damaged when the content of Al and B is too high, and the matrix material does not participate in the chemical reaction, and too much doping amount may hinder the intercalation and deintercalation of lithium ions.
Preferably, in step S2, the aluminum source is Al 2 O 3 、Al(OH) 3 One of them.
Preferably, the specific steps of the first calcination in step S2 are: placing the mixture of the precursor, the lithium source and the aluminum source in a sintering furnace, heating to 450-550 ℃ in an oxygen environment, preserving heat for 5-10h, cooling and taking out to obtain a sintering product A; the temperature rising rate is 2-7 ℃/min.
Preferably, in step S2, the boron source is B 2 O 3 。
Preferably, the specific steps of the second calcination in the step S2 are as follows: grinding the sintering product A, adding a boron source, heating to 700-800 ℃, preserving heat for 10-30 h, cooling and taking out to obtain a sintering product B; the temperature rising rate is 2-7 ℃/min.
The inventor finds in experiments that when aluminum boron doping is carried out, as the bond energy of B-O is 809kJ/mol and the chemical bond energy of Al-O is 542kJ/mol, al-O bonds are easier to form, al is preferentially combined with O, a potential energy barrier is formed inside after combination, and B is prevented from continuously entering, and the particles can only stay outside. Particularly, if the aluminum content is too high, the doping effect of boron can be disturbed, and the two elements are mutually interfered to cause poor doping effect and influence the electrochemical performance of the material.
The inventors have unexpectedly found that when the aluminum in the aluminum source is 0.1% -0.8% of the precursor molar amount; the boron in the boron source is 0.1% -0.8% of the precursor molar quantity, and when aluminum doping is performed first and then boron doping is performed, the prepared positive electrode material has the best battery performance, and particularly has excellent cycle performance and rate performance under high pressure conditions. The inventors analyzed that it is possible that during the charge-discharge cycle of the high nickel material, especially at high voltage, the material is subjected to excessive stress in the longitudinal direction, which is prone to generate voids, poor reversibility, resulting in poor material cycle performance, and the nickel-rich material generates a lot of unstable Ni during the charge process 4+ The capacity degradation is caused, and furthermore, the continuous appearance of Ni-O phase on the surface of the particles and the disorder of excessive Li/Ni have negative effects on the electrochemical performance, and the surface of the particles is particularly serious, so that the normal transportation of lithium ions is blocked to a certain extent. At the moment, by doping Al and B, the material is prevented from generating vacancies in the longitudinal direction due to overlarge stress, particles are prevented from being damaged, the stability of the material is enhanced, and the cycle performance is improved. Meanwhile, under high voltage, the electrolyte is easier to decompose, so that the material is corroded, and at the moment, the doped Al enters the layered structure to play a role in supporting the layered structure and prevent the structure from collapsing; whereas B residing outside the particles instead provides a protective effect on the particle surface. The doping amount of Al cannot be too high, otherwise, the doping of B is disturbed, and if the doping amount of B is too high, the relative content of active substances is reduced, and the lithium ions are affectedEmbedding and extracting, on the contrary, cause deterioration of charge and discharge performance of the material.
Preferably, the preparation method of the ternary positive electrode material specifically comprises the following steps:
step S1: preparing a precursor: weighing a nickel source, a cobalt source and a manganese source according to a molar ratio, mixing to prepare a salt solution, adding 0-100 ml of base solution into a reactor, adding the salt solution, a precipitator and a complexing agent into the reactor, controlling the pH value to be 11-12, the stirring speed to be 300-600 rpm, reacting at 40-60 ℃ to obtain a solid-liquid mixture, filtering and drying the solid-liquid mixture, and sieving the solid-liquid mixture with a 300-mesh sieve to obtain a precursor; the chemical formula of the precursor is Ni x Co y Mn z (OH) 2 Wherein x is more than or equal to 0.7 and less than or equal to 0.98,0.01, y is more than or equal to 0.1, z is more than or equal to 0.01 and less than or equal to 0.2, and x+y+z=1;
step S2: mixing a precursor and a lithium source according to a molar ratio, adding an aluminum source, placing the mixture in a sintering furnace, heating to 450-550 ℃ in an oxygen environment, preserving heat for 5-10h, cooling, and taking out to obtain a sintering product A, wherein the heating rate is 2-7 ℃/min; grinding the sintering product A, adding a boron source, heating to 700-800 ℃, preserving heat for 10-30 h, cooling, and taking out to obtain a sintering product B, wherein the heating rate is 2-7 ℃/min; grinding the sintered product B into powder to obtain the ternary positive electrode material, wherein the chemical formula of the ternary positive electrode material is Li (Ni x Co y Mn z ) 1-b-c Al b B c O 2 Wherein x is more than or equal to 0.7 and less than or equal to 0.98,0.01, y is more than or equal to 0.1, z is more than or equal to 0.01 and less than or equal to 0.2, and x+y+z=1; b is more than 0 and less than or equal to 0.015,0, c is more than or equal to 0.015, and b+c is more than 0 and less than or equal to 0.03.
Preferably, the ternary positive electrode material is a spheroid-like particle. More preferably, the ternary positive electrode material has a particle size of 5 to 15 μm.
The invention further provides application of the aluminum-boron co-doped ternary positive electrode material in a lithium ion battery.
The beneficial effects are that:
(1) According to the invention, proper amounts of Al and B are doped in the positive electrode material, and the specific Al/B doping sequence and doping amount are limited, so that the prepared positive electrode material has excellent electrochemical performance after modification, and the specific discharge capacity, the cycle performance and the multiplying power performance of the battery are effectively improved. Particularly in the high voltage range of 2.75-4.5V, has excellent cycle performance and rate performance.
(2) The invention uses the nickel-cobalt-manganese based precursor, adopts the high-nickel low-cobalt ternary cathode material, improves the specific capacity of the battery, reduces the content of cobalt in the battery, and reduces the material cost of the battery. The process is simple and easy to control, has high yield ratio, and is favorable for popularization and application of industrial mass production.
Drawings
FIG. 1 is an SEM image of a high nickel layered positive electrode material NCM9055-AB prepared in example 1 of the present invention;
FIG. 2 is an SEM image of a high nickel layered cathode material NCM9055-A1B1 prepared in example 2 of the present invention;
FIG. 3 is an SEM image of the high nickel layered cathode material NCM9055 prepared in comparative example 1 of the present invention;
FIG. 4 is an SEM image of the high nickel layered cathode material NCM9055-A prepared in example 2 of the present invention;
FIG. 5 is an SEM image of the high nickel layered cathode material NCM9055-B prepared in example 3 of the present invention;
FIG. 6 is an SEM image of the high nickel layered cathode material NCM9055-BA prepared in comparative example 4 of the present invention;
FIG. 7 is a graph showing the cycle curves of the high nickel layered cathode materials obtained in examples 1-2 and comparative examples 1-4 according to the present invention at a current of 1C (1C=180 mAh/g);
fig. 8 is a graph showing the rate performance curves of the high nickel layered cathode materials obtained in examples 1-2 and comparative examples 1-4 according to the present invention at different rates.
Detailed Description
For better illustrating the present invention, the technical scheme of the present invention is convenient to understand, and the present invention is further described in detail below. The following examples are merely illustrative of the present invention and are not intended to represent or limit the scope of the invention as defined in the claims.
The following are exemplary but non-limiting examples of the invention:
example 1
In one aspect, the embodiment provides an aluminum-boron co-doped ternary positive electrode material, wherein the preparation raw materials of the ternary positive electrode material comprise a precursor, a lithium source, an aluminum source and a boron source; the chemical formula of the ternary positive electrode material is Li (Ni 0.9 Co 0.05 Mn 0.05 ) 0.99 Al 0.005 B 0.005 O 2 。
The second aspect of the present embodiment provides a method for preparing a ternary positive electrode material, which specifically includes the following steps:
step S1: preparing a precursor: according to the mol ratio of 9:0.5:0.5 weighing NiSO 4 ·6H 2 O、CoSO 4 ·7H 2 O，MnSO 4 H 2 O, adding water into the mixture to prepare a salt solution, adding deionized water into a reaction kettle to serve as a base solution, adding 4mol/L of salt solution, 4mol/L of NaOH solution and 1.2mol/L of ammonia water into a reactor (the adding rate of the salt solution and the precipitant is 0.4ml/min, the adding rate of the complexing agent is 0.08 ml/min), controlling the pH value to be 11-12, the stirring rate to be 500rpm, reacting at 50 ℃ for 36 hours to obtain a solid-liquid mixture, filtering and drying the solid-liquid mixture, cooling the solid-liquid mixture at 110 ℃ for 8 hours, and sieving the solid-liquid mixture through a 300-mesh sieve to obtain a precursor; the chemical formula of the precursor is (Ni 0.9 Co 0.05 Mn 0.05 (OH) 2 )；
Step S2: precursor and LiOH.H 2 O is in a molar ratio of 1:1.05 mixing, adding 0.5% mol Al (Al as aluminum source) 2 O 3 ) Calcining the mixture in a tube furnace under the oxygen environment, heating to 500 ℃, preserving heat for 8 hours, cooling, and taking out to obtain a sintered product A, wherein the heating rate is 4 ℃/min; grinding the sintered product A, adding 0.5% mol B (boron source is B) 2 O 3 ) Heating to 750 ℃, preserving heat for 20 hours, cooling, taking out to obtain a sintered product B, wherein the heating rate is 4 ℃/min; grinding the sintered product B into powder to obtain the ternary positive electrode material, wherein the chemical formula of the ternary positive electrode material is Li (Ni 0.9 Co 0.05 Mn 0.05 ) 0.99 Al 0.005 B 0.005 O 2 The sample was designated NCM9055-AB.
Example 2
The embodiment provides an aluminum-boron co-doped ternary cathode material, and the specific implementation manner is the same as that of embodiment 1, and the difference between the specific implementation manner and embodiment 1 is that the specific implementation manner of step S2 is as follows:
precursor and LiOH.H 2 O is in a molar ratio of 1:1.05 mixing, adding 1% mol Al (Al source is Al) 2 O 3 ) Calcining the mixture in a tube furnace under the oxygen environment, heating to 500 ℃, preserving heat for 8 hours, cooling, and taking out to obtain a sintered product A, wherein the heating rate is 4 ℃/min; grinding the sintered product A, adding 1% mol B (boron source B 2 O 3 ) Heating to 750 ℃, preserving heat for 20 hours, cooling, taking out to obtain a sintered product B, wherein the heating rate is 4 ℃/min; grinding the sintered product B into powder to obtain the ternary positive electrode material, wherein the chemical formula of the ternary positive electrode material is Li (Ni 0.9 Co 0.05 Mn 0.05 ) 0.98 Al 0.01 B 0.01 O 2 Is designated NCM9055-A1B1.
Comparative example 1
The present example provides a ternary positive electrode material, and the specific embodiment is the same as example 1, and differs from example 1 in that in step S2, no aluminum source and no boron source are added, and the chemical formula of the ternary positive electrode material is LiNi 0.9 Co 0.05 Mn 0.05 O 2 And is designated NCM9055.
Comparative example 2
The present embodiment provides a ternary cathode material, and the specific embodiment is the same as embodiment 1, and differs from embodiment 1 in that the specific steps in step S2 are as follows:
precursor and LiOH.H 2 O is in a molar ratio of 1:1.05 mixing, adding 1.0% mol Al (Al as aluminum source) 2 O 3 ) Calcining the mixture in a tube furnace under the oxygen environment, heating to 500 ℃, preserving heat for 8 hours, cooling, and taking out to obtain a sintered product A, wherein the heating rate is 4 ℃/min; grinding the sintering product A, heating to 750 ℃, preserving heat for 20h, cooling and taking out to obtain a sintering product B,the temperature rising rate is 4 ℃/min; grinding the sintered product B into powder to obtain the ternary positive electrode material, wherein the chemical formula of the ternary positive electrode material is Li (Ni 0.9 Co 0.05 Mn 0.05 ) 0.99 Al 0.01 O 2 The test piece is denoted as NCM9055-A.
Comparative example 3
The present embodiment provides a ternary cathode material, and the specific embodiment is the same as embodiment 1, and differs from embodiment 1 in that the specific steps in step S2 are as follows:
precursor and LiOH.H 2 O is in a molar ratio of 1:1.05 mixing, adding 1% mol B (boron source B) 2 O 3 ) Calcining the mixture in a tube furnace under the oxygen environment, heating to 500 ℃, preserving heat for 8 hours, cooling, and taking out to obtain a sintered product A, wherein the heating rate is 4 ℃/min; grinding the sintering product A, heating to 750 ℃, preserving heat for 20 hours, cooling, and taking out to obtain a sintering product B, wherein the heating rate is 4 ℃/min; grinding the sintered product B into powder to obtain the ternary positive electrode material, wherein the chemical formula of the ternary positive electrode material is Li (Ni 0.9 Co 0.05 Mn 0.05 ) 0.99 B 0.01 O 2 Is designated NCM9055-B.
Comparative example 4
The present embodiment provides an aluminum-boron co-doped ternary cathode material, and the specific implementation manner is the same as that of embodiment 1, and differs from embodiment 1 in that the specific steps of step S2 are as follows:
precursor and LiOH.H 2 O is in a molar ratio of 1:1.05 mixing, adding 0.5% mol B (boron source B) 2 O 3 ) Calcining the mixture in a tube furnace under the oxygen environment, heating to 500 ℃, preserving heat for 8 hours, cooling, and taking out to obtain a sintered product A, wherein the heating rate is 4 ℃/min; grinding the sintered product A, adding 0.5% mol Al (Al as Al source) of the precursor molar quantity 2 O 3 ) Heating to 750 ℃, preserving heat for 20 hours, cooling, taking out to obtain a sintered product B, wherein the heating rate is 4 ℃/min; grinding the sintered product B into powder to obtain the ternary positive electrode material, wherein the chemical formula of the ternary positive electrode material is Li (Ni 0.9 Co 0.05 Mn 0.05 ) 0.99 B 0.005 Al 0.005 O 2 The test piece was designated as NCM9055-BA.
Performance testing
1. Image characterization
SEM tests were performed on the cathode materials of example 1 and comparative examples 1 to 4, and SEM characterization graphs are shown in fig. 1 to 5. As can be seen from FIG. 1, the ternary positive electrode material prepared by the method is of similar spherical particles and has good compactness. The primary particles on the surface are finer, the surface is denser, the structural stability is higher in the circulation process, and the generation of surface microcracks can be reduced. But at the same time, the deintercalation of lithium ions in the initial stage is difficult, and the capacity of the battery is reduced.
2. Electrochemical testing
Electrochemical performance tests were performed on the high nickel layered cathode materials of example 1 and comparative examples 1 to 4 of the present invention.
The ternary cathode material end products prepared in example 1 and comparative examples 1 to 4 were dissolved in N-methyl-2-pyrrolidone (NMP) with a binder (polyvinylidene fluoride (PVDF)) and a conductive agent (acetylene black, super P) in a mass ratio of 8:1:1, and placed on a magnetic stirrer for 12 hours. The slurry was then coated on an Al foil, the electrode sheet was dried, and then cut into circular electrode sheets having a diameter of 14 mm. The half-cell was then assembled in an argon atmosphere glove box, and the cell was allowed to stand in the glove box for 24h. Then, the cycle performance and the multiplying power performance of the battery are tested (1 C=180 mAh/g), the charge and discharge cycle is carried out under the condition that the test voltage is 2.75-4.5V, and the first discharge capacity, the cycle discharge capacity and the capacity retention rate are tested.
The test results are shown in Table 1 below.
TABLE 1
Figure BDA0004172643780000101
The result shows that the positive electrode material still maintains 127mAh/g after being subjected to a half-cell test and the NCM9055-AB has a 1C 200 cycle discharge capacity within a voltage range of 2.75-4.5V, and the capacity retention rate is 62.4% on the basis of higher discharge specific capacity; the 5C multiplying power in the multiplying power performance can reach 182mAh/g, and the multiplying power performance and the structural stability are excellent.
The foregoing description of the preferred embodiments of the invention is merely illustrative of the invention and is not intended to be limiting. It should be noted that, for those skilled in the art, other equivalent modifications can be made in light of the technical teaching provided by the present invention, and the present invention can be implemented as the scope of protection.

Claims (10)

1. The aluminum-boron co-doped ternary positive electrode material is characterized in that the preparation raw materials of the ternary positive electrode material comprise a precursor, a lithium source, an aluminum source and a boron source; the chemical formula of the ternary positive electrode material is
Li(Ni x Co y Mn z ) 1-b-c Al b B c O 2 Wherein x is more than or equal to 0.7 and less than or equal to 0.98,0.01, y is more than or equal to 0.1, z is more than or equal to 0.01 and less than or equal to 0.2, and
x+y+z=1; b is more than 0 and less than or equal to 0.015,0, c is more than or equal to 0.015, and b+c is more than 0 and less than or equal to 0.03.
2. The preparation method of the aluminum-boron co-doped ternary cathode material according to claim 1, wherein the preparation method of the ternary cathode material comprises the following steps:
step S1: preparing a precursor: weighing a nickel source, a cobalt source and a manganese source, mixing to prepare a salt solution, adding the salt solution, a precipitator and a complexing agent into a reactor, reacting at 40-60 ℃ to obtain a solid-liquid mixture, filtering the solid-liquid mixture, and drying to obtain a precursor;
step S2: mixing the precursor with a lithium source, adding an aluminum source, and performing first calcination to obtain a sintered product A; adding a boron source, performing secondary calcination to obtain a sintered product B, and grinding the sintered product B to powder to obtain the ternary anode material.
3. The method for preparing an aluminum-boron co-doped ternary cathode material according to claim 2, wherein the chemical formula of the precursor is Ni x Co y Mn z (OH) 2 Wherein x is more than or equal to 0.7 and less than or equal to 0.98,0.01, y is more than or equal to 0.1, z is more than or equal to 0.01 and less than or equal to 0.2, and x+y+z=1.
4. The method for preparing an aluminum-boron co-doped ternary cathode material according to claim 2, wherein in the step S1, the nickel source is NiSO 4 ·6H 2 O、Ni(CH 3 COO) 2 ·4H 2 One of O; the cobalt source is CoSO 4 ·7H 2 O、Co(CH 3 COO) 2 ·4H 2 One of O; the manganese source is MnSO 4 ·H 2 O、MnCO 3 、Co(CH 3 COO) 2 ·4H 2 One of O.
5. The method for preparing the aluminum-boron co-doped ternary cathode material according to claim 2, wherein in the step S1, the precipitant is 0.5-10 mol/L NaOH solution; the complexing agent is 0.05-3 mol/L ammonia water solution.
6. The method for preparing the aluminum-boron co-doped ternary cathode material according to claim 2, wherein the concentration ratio of the salt solution, the precipitant and the complexing agent in the step S1 is 1:0.8-1.2:0.02-0.05.
7. The method for preparing an aluminum-boron co-doped ternary cathode material according to claim 2, wherein in the step S2, aluminum in the aluminum source is 0-1.5% of the molar amount of the precursor and is not equal to 0;
boron in the boron source is 0-1.5% of the precursor molar amount and is not equal to 0.
8. The method for preparing an aluminum-boron co-doped ternary cathode material according to claim 2, wherein the specific steps of the first calcination in the step S2 are as follows: placing the mixture of the precursor, the lithium source and the aluminum source in a sintering furnace, heating to 450-550 ℃ in an oxygen environment, preserving heat for 5-10h, cooling and taking out to obtain a sintering product A; the temperature rising rate is 2-7 ℃/min.
9. The method for preparing an aluminum-boron co-doped ternary cathode material according to claim 2, wherein the specific steps of the second calcination in the step S2 are as follows: grinding the sintering product A, adding a boron source, heating to 700-800 ℃, preserving heat for 10-30 h, cooling and taking out to obtain a sintering product B;
the temperature rising rate is 2-7 ℃/min.
10. A lithium ion battery comprising the aluminum-boron co-doped ternary cathode material of claim 1 or prepared by the preparation method of any one of claims 2-9.
CN202310381891.9A 2023-04-11 2023-04-11 Aluminum-boron co-doped ternary positive electrode material and preparation method and application thereof Pending CN116387508A (en)

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