CN111224096A

CN111224096A - Power device and preparation method thereof

Info

Publication number: CN111224096A
Application number: CN201911238295.5A
Authority: CN
Inventors: 谢中淮
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-12-06
Filing date: 2019-12-06
Publication date: 2020-06-02

Abstract

The invention provides a power device and a preparation method thereof, the power device is improved in stability under high voltage by adopting novel materials, and the prepared power device is high in specific capacity, good in large-current cycle performance and long in cycle life. The method provided by the invention has the advantages of simple process and high yield, and is suitable for industrial production.

Description

Power device and preparation method thereof

Technical Field

The invention relates to the technical field of power devices, in particular to a power device containing an improved compound.

Background

Lithium-based power devices are currently the most demanding mobile power devices in the market due to their high specific capacity and high energy density. At present, the commonly used anode materials of the lithium power device mainly comprise lithium nickelate, lithium manganate, lithium iron phosphate and other materials, but the materials generally have the defects of difficult sufficient energy release under high voltage and large current, and the cycle life is severely attenuated under the large current. Therefore, a new lithium-based power device which can adapt to high-voltage and high-current working environments and has stable cycle performance, high specific capacity and long cycle life is urgently needed.

Disclosure of Invention

The specific scheme is as follows:

a power device comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, the positive electrode comprising a positive electrode active material, a conductive agent, and a binder, the negative electrode comprising a negative electrode active material, a binder; the positive electrode active material has a composition of the following general formula (1):

LiNi_1-x-yM_xN_yBO_3-zA_2z(1)

wherein M is at least one element selected from the group consisting of Ti, Cr, Al, Mg, Cu and Zn, N is at least one element selected from the group consisting of Bb, Si, As, Sn, La, Ce and Nd, A is at least one element selected from halogen and S, 0< x <0.358, 0< y <0.336, and 0< z < 0.199.

Further, a preparation method of the positive electrode active material is provided, which comprises the following steps: weighing and mixing raw materials of a lithium source, a Ni source, an M source, an N source and a boron source according to a stoichiometric ratio, ball-milling for 2-8 hours in a solvent medium, pre-drying for 1-3 hours in an oven at 50-80 ℃ to obtain a sol-gel precursor, and then carrying out spray drying to obtain precursor powder; heating the precursor at a heating rate of 1-10 ℃/min in a mixed atmosphere of inert gas and A source gas with a certain mixing volume ratio, carrying out constant-temperature heat treatment at 600-800 ℃ for 6-30 hours, and cooling to room temperature along with the furnace to obtain LiNi_1-x-yM_xN_yBO3_-zA_2zAnd obtaining a positive active material product.

Furthermore, the power device of the invention is any one of common lithium batteries such as a lithium ion battery and a lithium polymer battery.

Further, M is selected from Ti.

Further, the N is selected from Sn.

Further, the boron source is boric acid.

Further, the heat treatment temperature is 600 ℃, and the heat treatment time is 28 hours.

The invention has the following beneficial effects:

1. because Ni has a higher discharge platform in charge-discharge cycles, the Ni-based doped anode active material can enable the anode material to have a charge voltage of more than 4.3V, and can fully release energy in the anode.

2. The M source contains elements, so that the electric conductivity of the anode material can be improved, large-current discharge is facilitated, the cost of the material can be reduced, and the high-rate discharge performance of the power device is obviously improved.

3. The N source contains elements with stable performance, the crystal structure of the material can be stabilized by doping the N source elements, and the circulation stability of the power device can be improved when high voltage and large current are applied.

4. The source A contains elements which can improve the crystal surface morphology of the anode material, enhance the compatibility of the anode material and the electrolyte and improve the conduction capability of lithium ions, thereby improving the large-current discharge capability and the cycling stability of the anode material.

Through the scheme, the power device has the advantages of improved stability under high voltage, high specific capacity, good large-current cycle performance and long cycle life.

Drawings

Fig. 1 is an SEM image of the product prepared in example 1.

Detailed Description

The present invention will be described in more detail below with reference to specific examples, but the scope of the present invention is not limited to these examples.

Test example: the power device comprises a positive electrode, a negative electrode and a diaphragm arranged between the positive electrode and the negative electrode, wherein the positive electrode comprises a positive electrode active material, a conductive agent and a binder, and the negative electrode comprises a negative electrode active material and a binder. The diaphragm comprises a polypropylene/polyethylene composite film; the negative electrode is natural graphite; the electrolyte comprises ethylene carbonate: propylene carbonate: ethyl methyl carbonate 2:1:1 and lithium salt 1M lithium hexafluoroborate.

The positive electrode active material used in each example was the positive electrode material prepared in each example below.

Example 1

Weighing raw material Li according to stoichiometric ratio₂CO₃、TiO₂、NiO、SnO₂Mixing with boric acid, ball-milling for 5 hours in an ethanol medium, pre-drying for 2 hours in an oven at 60 ℃ to obtain a sol-gel precursor, and then carrying out spray drying to obtain precursor powder; heating the precursor at a heating rate of 10 ℃/min in a mixed atmosphere of nitrogen and fluorine gas with a volume ratio of 85:15, carrying out constant-temperature heat treatment at 800 ℃ for 26 hours, and cooling to room temperature along with the furnace to obtain LiNi_0.601Ti_0.161Sn_0.238BO_3.97 ₁F_0.058And obtaining a positive active material product. As can be seen from the SEM image of fig. 1, the product particles were uniform, mostly spherical in shape, and had micron-sized particle diameters.

Example 2

Weighing raw materials LiOH, NiO, Ti powder and SnO according to stoichiometric ratio₂Mixing ammonium hydrogen borate tetrahydrate, ball-milling for 3 hours in an ethanol medium, pre-drying for 1.6 hours in an oven at 56 ℃ to obtain a sol-gel precursor, and then performing spray drying to obtain precursor powder; heating the precursor at a heating rate of 5 ℃/min in a mixed atmosphere of argon and chlorine with a volume ratio of 80:20, carrying out constant-temperature heat treatment at 600 ℃ for 28 hours, and cooling to room temperature along with the furnace to obtain the LiNi_0.581Ti_0.153Sn_0.266BO_3.972Cl_0.056And obtaining a positive active material product.

Example 3

Weighing raw material Li according to stoichiometric ratio₂CO₃、NiO、MgO、SiO₂Mixing ammonium hydrogen borate tetrahydrate, ball-milling for 6 hours in an ethanol medium, pre-drying for 1 hour in an oven at 80 ℃ to obtain a sol-gel precursor, and then performing spray drying to obtain precursor powder; heating the precursor at a heating rate of 8 ℃/min in a mixed atmosphere of argon and bromine gas with a volume ratio of 65:35, carrying out constant-temperature heat treatment at 700 ℃ for 25 hours,cooling to room temperature along with the furnace to obtain LiNi_0.666Mg_0.166Si_0.16 ₈BO_3.982Br_0.036And obtaining a positive active material product.

Comparative example 1;

unlike the previous examples, the positive active material is LiNiBO prepared by a conventional solid phase method₃The other components were the same as those in the test examples.

The following table shows the test data of the examples and comparative examples, the cycle current was 1C, the charge cut-off voltage was 4.5V, and the discharge cut-off voltage was 2.7V. Therefore, compared with the comparative example adopting the conventional nickel borate, the power device has higher specific capacity under high voltage and large current, and the cycle performance and the cycle life are obviously improved.

TABLE 1

While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention.

Claims

1. A power device comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, the positive electrode comprising a positive electrode active material, a conductive agent, and a binder, the negative electrode comprising a negative electrode active material, a binder; the positive electrode active material has a composition of the following general formula (1):

LiNi_1-x-yM_xN_yBO3_-zA_2z(1)

2. Preparation of the positive electrode active material as claimed in claim 1A method comprising the steps of: weighing and mixing raw materials of a lithium source, a Ni source, an M source, an N source and a boron source according to a stoichiometric ratio, ball-milling for 2-8 hours in a solvent medium, pre-drying for 1-3 hours in an oven at 50-80 ℃ to obtain a sol-gel precursor, and then carrying out spray drying to obtain precursor powder; heating the precursor at a heating rate of 1-10 ℃/min in a mixed atmosphere of inert gas and A source gas with a certain mixing volume ratio, carrying out constant-temperature heat treatment at 600-800 ℃ for 6-30 hours, and cooling to room temperature along with the furnace to obtain LiNi_1-x-yM_xN_yBO3_-zA_2zAnd obtaining a positive active material product.

3. The power supply of claim 1, said M being selected from Ti.

4. The power supply of claim 1, said N being selected from Sn.

5. The method of claim 2, wherein the boron source is boric acid.

6. The method of claim 2, wherein the heat treatment temperature is 600 ℃ and the heat treatment time is 28 hours.