Composite material, preparation method of composite material, and lithium ion battery comprising composite material

A composite material, lithium source technology, applied in battery electrodes, secondary batteries, circuits, etc., can solve the problems of organic consumption, increased cost, and insufficient connection, achieving obvious cost-effective advantages, improved pressure resistance, and good consistency Effects of Sex and Uniformity

Active Publication Date: 2014-10-01

NEC (CHINA) CO LTD

4 Cites 9 Cited by

AI-Extracted Technical Summary

Problems solved by technology

This method requires secondary roasting, which consumes a large amount of organic matter and increases...

Method used

The composite material that the embodiment of the present invention provides is multi-layer core-shell structure, and inner core selects NCA material, and middle shell selects NCM material, and outer shell selects spinel lithium nickelate material. Since the shell material itself has a certain capacity, the coating on the high-capacity core material will not cause a large loss of the capacity of the core material; and because the shell material has low alkalinity and good cycle performance, the high-alkaline After the core material is coated, it can reduce the alkalinity of the composite material and improve the cycle performance of the composite material; in addition, the outer shell layer is made of spinel lithium nickel oxide material, and the discharge platform of this material is about 4.7-4.8V. The discharge platform is higher than the middle layer and the inner core, which improves the overall pressure resistance of the material. At the same time, due to the poor oxidation of the ma...

Abstract

The invention discloses a composite material, a preparation method of the composite material, and a lithium ion battery comprising the composite material, and belongs to the field of lithium ion battery materials. The composite material is in a core-shell structure. A shell layer of the composite material comprises a middle layer and an outer layer coated outside the middle layer. An inner core of the composite material is Li(NixCoyAlz)O2; the middle layer is Li(Ni1/3Co1/3Mn1/3)O2; the outer layer is LiNi0.5Mn1.5O4; and a molar ratio of the inner core to the middle layer to the outer layer of the composite material is a:b:c, wherein a+b+c=1, b is greater than 0 and less than 0.5, c is greater than 0 and less than 0.5, x+y+z=1, y=0.15, and z is greater than or equal to 0.03 and is less than or equal to 0.05. The composite material has the characteristics of comparatively high capacity, low alkalinity and electrolyte resistance, has good cycling stability and safety performance, has an obvious cost performance advantage, and is more suitable for application of a power battery. Structural precursors of the layers of the composite material are sequentially formed by utilizing a coprecipitation synthesis technology, so that good consistency and good homogeneity are achieved and the layers are tightly connected with each other. Besides, the composite material can be obtained by a single roasting process; and the cost can be lowered effectively.

Application Domain

Cell electrodesSecondary cells

Technology Topic

CoprecipitationCyclic stability +9

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Examples

Experimental program(17)
Comparison scheme(3)

Example Embodiment

[0043] Example 1

[0044] The embodiment of the present invention provides a composite material. The composite material has a multilayer core-shell structure. The shell layer of the composite material includes an intermediate layer and an outer layer covering the intermediate layer. The core of the composite material is Li(Ni x Co y Al z )O 2 , The middle layer is Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 , The outer layer is LiNi 0.5 Mn 1.5 O 4 , The molar ratio of the inner core, middle layer, and outer layer of the composite material is a:b:c, where a+b+c=1, 0 <0.5, 0 <0.5, x+y+z=1, y=0.15, 0.03≤z≤0.05.

[0045] The composite material provided by the embodiment of the present invention has a multi-layer core-shell structure, the core is selected from NCA material, the middle shell layer is selected from NCM material, and the outer shell layer is selected from spinel lithium nickelate material. Because the shell material itself has a certain capacity, coating on the high-capacity core material will not cause a large loss in the capacity of the core material; and because the shell material has low alkalinity and good cycle performance, the alkalinity is high. The inner core material can reduce the alkalinity of the composite material and improve the cycle performance of the composite material. In addition, the outer shell layer is made of spinel lithium nickelate material, and the discharge platform of this material is about 4.7-4.8V. The discharge platform higher than the intermediate layer and the inner core improves the pressure resistance of the material as a whole. At the same time, due to the poor oxidation of the material, it is not easy to react with the electrolyte. The electrolyte is in contact with the electrolyte and is not easy to react with the electrolyte, which avoids the occurrence of dangerous situations such as swelling or even explosion caused by the reaction of the electrode material and the electrolyte when the battery is charged and discharged, and improves the safety and stability of the battery.

[0046] Therefore, the composite material provided by the embodiments of the present invention has the characteristics of higher capacity, low alkalinity, and electrolyte resistance, better cycle stability and safety performance, obvious cost-effective advantages, and is more suitable for power battery applications.

Example Embodiment

[0047] Example 2

[0048] The embodiment of the present invention provides a preparation method of a composite material, the preparation method includes:

[0049] Step 1: A composite material precursor with a core-shell structure is obtained sequentially by co-precipitation reaction. The shell layer of the composite material precursor includes an intermediate layer and an outer layer covering the intermediate layer. The core of the composite material precursor is (Ni x Co y Al z )(OH) 2 , The middle layer is (Ni 1/3 Co 1/3 Mn 1/3 )(OH) 2 , The outer layer is Ni 0.25 Mn 0.75 (OH) 2;

[0050] Step 2: The composite material precursor and the lithium source are uniformly mixed in a molar ratio of 1:1 to 1.1, then roasted, and then cooled, crushed, and sieved to obtain an inner core of Li(Ni x Co y Al z )O 2 , The middle layer is Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 , The outer layer is LiNi 0.5 Mn 1.5 O 4 The composite material, the molar ratio of the inner core, middle layer and outer layer of the composite material is a:b:c, where a+b+c=1, 0 <0.5, 0 <0.5, x+y+z=1, y=0.15, 0.03≤z≤0.05.

[0051] In the embodiment of the present invention, the precursors of each layer structure of the composite material are sequentially formed by using the co-precipitation synthesis process, so that the layers of the composite material have better consistency and uniformity and the layers are tightly connected. In addition, the composite material can be obtained by mixing the precursor of the composite material with the lithium source and firing once, which can effectively reduce the cost.

[0052] Step 1 of the embodiment of the present invention specifically includes:

[0053] Step 1a: Prepare a certain amount of ternary salt solution A of Ni, Co, Al according to the molar ratio of Ni, Co, and Al as x:y:z, and according to the molar ratio of Ni, Co, and Mn as 1:1: A certain amount of Ni, Co, Mn ternary salt solution B is prepared in the ratio of 1, and a certain amount of Ni, Mn binary salt solution C is prepared according to the molar ratio of Ni, Mn of 0.25:0.75, and it is prepared according to the requirements of use A certain amount of alkali solution with a certain concentration.

[0054] Step 1b: After preparation, the ternary salt solution A of Ni, Co, and Al is added dropwise to the high-speed rotating reactor, while the alkali solution is added dropwise to control the pH value of the mixture in the reactor to 10-12 for co-precipitation reaction to obtain The solid phase is (Ni x Co y Al z )(OH) 2 的solid-liquid mixture;

[0055] When (Ni x Co y Al z )(OH) 2 When the particles are large enough, stop the dripping of the ternary salt solution A of Ni, Co, Al, and add the ternary salt solution B of Ni, Co, Mn to the reactor, and control the pH of the mixture in the reactor to 10 -12 Continue the co-precipitation reaction, in (Ni x Co y Al z )(OH) 2 The middle layer (Ni 1/3 Co 1/3 Mn 1/3 )(OH) 2;

[0056] When a certain thickness of the intermediate layer is formed, stop dripping the ternary salt solution B of Ni, Co, Mn, and add the binary salt solution C of Ni, Mn to the reactor, and control the pH of the mixture in the reactor to 10 -12 Continue the co-precipitation reaction until an outer layer of Ni with a certain thickness is formed outside the intermediate layer 0.25 Mn 0.75 (OH) 2 , Stop the reaction;

[0057] Step 1c: the solid-liquid mixture after the reaction is separated by centrifugation, the separated solid phase substance is washed to neutrality, and then dried at 100-200° C. for 1-10 hours to obtain a core-shell structure composite material precursor.

[0058] Among them, (Ni x Co y Al z )(OH) 2 The size of the particles, the thickness of the middle layer and the outer layer can be selected according to the needs of a specific lithium ion battery electrode; the dripping speed of each solution is adjusted according to the growth conditions of the particles of each layer.

[0059] The roasting described in step 2 of the embodiment of the present invention specifically includes:

[0060] Put it in a muffle furnace and roast at 700-800℃ for 2-5 hours, then continue to raise the temperature at 800℃-850℃ for 2-5 hours, and finally continue to raise the temperature to 850-950℃ and roast for 2-5 hours.

[0061] Due to the different materials of the inner core, middle shell, and outer shell, the temperature at which the crystal lattice is formed, and the speed at which lithium ions enter the crystal lattice are also different. Therefore, segmented calcination under this condition can not only make each layer better The formation of a lattice, and is conducive to the rapid entry of lithium ions into the lattice of each layer.

[0062] In the embodiment of the present invention:

[0063] The lithium source is one of lithium hydroxide, lithium nitrate, and lithium carbonate, preferably lithium carbonate.

[0064] Preferably, the speed of the reactor is 180rps-220rps.

[0065] At this speed, it is more conducive to forming a uniform and stable composite material precursor, making the connection between the layers of the composite material precursor closer.

[0066] The ternary salt solution of Ni, Co, Al is one or more of the acetate solution, nitrate solution, sulfate solution, and chloride solution of Ni, Co, and Al. The Ni The ternary salt solution of Co, Mn is one or more of the acetate solution, nitrate solution, sulfate solution, and chloride solution of Ni, Co, and Mn. The metasalt solution is one or a combination of Ni and Mn acetate solutions, nitrate solutions, sulfate solutions, and chloride solutions.

[0067] Preferably, the alkali solution is sodium hydroxide solution or ammonia water.

Example Embodiment

[0068] Example 3

[0069] Prepare 9L Ni, Co, Al nitrate solution A with a concentration of 1mol/L, wherein the molar ratio of Ni, Co, Al is 0.8:0.15:0.05; prepare 0.05L Ni, Co, Mn nitric acid with a concentration of 1mol/L Salt solution B, in which the molar ratio of Ni, Co, and Mn is 1:1:1; prepare 1 L of Ni, Mn nitrate solution C with a concentration of 1 mol/L, where the molar ratio of Ni to Mn is 0.25:0.75; Prepare a sufficient amount of 6mol/L NaOH alkali solution.

[0070] Inject solution A at a rate of 1L/h into a reactor with a rotation speed of 200rps, and at the same time inject 6mol/L NaOH alkali solution, keep the pH value in the reactor between 10-11, after the solution A is added dropwise, Immediately add solution B gradually to the reactor at a rate of 0.5L/h. After 0.1h, solution B is completely injected into the reactor, and then immediately add solution C to the reactor at a rate of 0.5L/h, and solution C is dripped After the addition is complete, the reaction is ended. The solid-liquid mixture after the reaction is separated by centrifugation, washed to neutrality, and dried at 100°C for 10 hours to obtain a molecular formula of 0.9 (Ni 0.8 Co 0.15 Al 0.05 )(OH) 2 ·0.05(Ni 1/3 Co 1/3 Mn 1/3 )(OH) 2 ·0.1Ni 0.25 Mn 0.75 (OH) 2 Composite precursors.

[0071] The dried composite material precursor and lithium carbonate are mixed uniformly at a molar ratio of 1:1.05, and then put into the muffle furnace. First, it is calcined at 750°C for 3 hours, then heated to 850°C for 5 hours, and finally heated to 950°C. It is calcined at ℃ for 2 hours, and the calcined material is crushed and sieved to obtain a modified multilayer composite material 0.9Li(Ni 0.8 Co 0.15 Al 0.05 )O 2 ·0.05Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 ·0.05LiNi 0.5 Mn 1.5 O 4.

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Classification and recommendation of technical efficacy words

Improve safety performance and stability performance
Improve pressure resistance

Protective device for agricultural buried line

InactiveCN109936122AImprove safety performance and stability performanceRealize remote sending and receiving

Owner:南晓鹏

Composite material, preparation method of composite material, and lithium ion battery comprising composite material

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

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Examples

Example Embodiment

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Example Embodiment

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Description & Claims & Application Information

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