WO2016202163A1

WO2016202163A1 - Method for synthesizing lithium-ion positive-electrode material linio2/c

Info

Publication number: WO2016202163A1
Application number: PCT/CN2016/083773
Authority: WO
Inventors: 田东
Original assignee: 田东
Priority date: 2015-06-16
Filing date: 2016-05-28
Publication date: 2016-12-22
Also published as: CN105047869A

Abstract

A method for synthesizing a lithium-ion positive-electrode material LiNiO₂/C comprises the following steps: 1) mixing nickel oxide and an organic carbon source by adding water, performing spray granulation after ball-milling treatment, pre-treating obtained powder in an inert atmosphere, to obtain carbon-covering nickel oxide powder; 2) dissolving a lithium source in water, adding the nickel oxide powder obtained in the step 1), and performing spray granulation after ball-milling treatment, to obtain dried powder; 3) treating the dried powder obtained in the step 2) in an inert atmosphere, further performing high-temperature heat treatment, and obtaining the lithium-ion positive-electrode material of LiNiO₂/C through air classification. Coating nickel oxide with carbon first can prevent the agglomeration of lithium nickelate during subsequent high-temperature treatment, and therefore can prevent the formation of excessively large lithium nickelate grains, thereby improving the electrical conductivity of the material and enhancing the cyclic stability of lithium nickelate.

Description

Method for synthesizing lithium ion cathode material LiNiO2/C

Technical field

The invention relates to a cathode material for a lithium ion battery, in particular to a method for synthesizing a lithium ion cathode material LiNiO ₂ /C prepared by a carbon-coated nickel oxide process.

Background technique

At present, with the shortage of global petroleum resources and the deteriorating climate environment, the development of human society faces severe challenges. The development of clean and energy-efficient new energy vehicles has been highly valued by countries around the world. The development of new energy vehicles is the key to their power supply. Lithium-ion batteries have the advantages of high energy density, small self-discharge, no memory effect, wide operating voltage range, long service life and no environmental pollution. They are the main power source for new energy vehicles. The key electrode material of lithium ion battery is the final determinant of battery performance, and the positive electrode material plays an important role in improving the performance of lithium ion battery. Therefore, the development of high-performance, low-cost cathode materials is of great significance to promote the development of new energy vehicles and related emerging industries.

The positive electrode material is one of the most critical factors affecting the energy density, specific energy, and lifetime of a lithium ion battery. Among the existing positive electrode materials, the layered structure positive electrode material is still the mainstream. The first-generation layered material LiNiO ₂ has good electrochemical stability and excellent cycle performance, but its capacity is only 50% of its theoretical capacity, and there are major problems such as resources and safety; LiNiO2 has the highest specific capacity, but it is difficult to synthesize. There is a big safety hazard; LiMnO _{2 has} good thermal stability and is inexpensive, but the obvious phase transition during charging and discharging leads to poor cycle stability. Multi-layered cathode material, such as LiNi1/3Ni1/3Mn1/3 O2, LiNi0.8A10.2O2, combines the advantages of existing layered structural materials to achieve a specific energy of 160mAg/g, but high Ni and Ni in the material. The content still has problems such as cost and resources, and safety is also a fatal shortcoming of the material. Spinel-type LiMn2O4 has been commercialized due to its high safety and low cost, and its relatively low specific energy or specific power has become the most deadly shortcoming of these two materials, hindering these two. The field of application of materials.

Lithium nickelate is one of the candidate materials for cathode materials for secondary lithium ion batteries. It is considered to be the most promising cathode material for lithium ion secondary batteries. Nickel lithium oxy-oxide cathode materials are used. The cost of lithium ion secondary batteries will be lower than that of lithium. There is a large reduction in the cobalt oxygen system. However, LiNiO ₂ applications are currently limited by many unfavorable factors, including: stoichiometric LiNiO _{2 is} difficult to synthesize, and small changes in synthesis conditions lead to non-stoichiometric LiNiO ₂ production: non-stoichiometric LiNiO ₂ due to lithium and nickel atoms The exchange of atomic positions in the layer deteriorates the electrochemical performance and the specific capacity decreases significantly; the first cycle has about 20% irreversible capacity; the thermal stability is poor, and it is not resistant to overshoot. All of these are closely related to their own crystal structure, and the crystal structure is closely related to the preparation method and process. Therefore, the modification of the conventional lithium nickelate to enhance the capacity of the LiNiO ₂ positive electrode material is one of the most effective methods for improving the material properties.

Summary of the invention

The object of the present invention is to provide a method for synthesizing a lithium ion cathode material LiNiO ₂ /C prepared by a carbon-coated nickel oxide process, which is simple in process route and suitable for large-scale industrial production.

The invention comprises the following steps:

1) mixing nickel monoxide and an organic carbon source with water, ball milling treatment, spray granulation, and the obtained powder is pretreated in an inert atmosphere to obtain carbon coated nickel oxide powder;

2) dissolving the lithium source in water, adding the nickel niobate powder obtained in the step 1), and then ball-milling and then spray granulating to obtain a dry powder;

3) The dry powder obtained in the step 2) is treated in an inert atmosphere, and then subjected to a high-temperature heat treatment to obtain a lithium ion positive electrode material LiNiO ₂ /C by gas flow classification.

In the step 1), the organic carbon source may be one of water-soluble organic substances, and the water-soluble organic substance may be selected from the group consisting of glucose, sucrose, fructose, polyethylene glycol, polyacrylic acid, and shell polymerization. One of sugar and the like; the time of the ball milling treatment is 5 to 10 h; the temperature of the pretreatment is 400 to 500 ° C, and the pretreatment time is 5 to 8 h.

In the step 2), the lithium source may be one of a water-soluble lithium salt lithium acetate and lithium hydroxide; the ball milling treatment time is 2 to 3 hours.

In the steps 1) and 2), the nickel oxide and lithium sources are n (Li):n (Ni) = 1.03 to 1.07 in terms of elemental molar amount; in the step 1), the mass of the organic carbon source is 10% to 15% of the mass of the nickel oxide; in the steps 1) and 2), the water may be used without brine, wherein the water in the step 1) is added in an amount of 3 to 4 times the mass ratio of nickel monoxide. Step 2) The amount of water added is 3-4 times the mass of the carbon coated nickel oxide powder by mass ratio.

In the steps 1) and 3), the inert atmosphere may be nitrogen gas or argon gas or the like.

In the step 3), the treatment temperature is 500 to 600 ° C, the treatment time is 10 to 20 h; the high temperature heat treatment temperature is 750 to 850 ° C, and the high temperature heat treatment time is 2 to 20 h.

Compared with the conventional method for synthesizing lithium ion positive electrode material LiNiO ₂ , the invention has the advantages that the nickel oxide of the synthetic raw material is first coated with carbon to avoid the agglomeration of lithium nickelate caused by high temperature treatment in the later stage, and the prevention of lithium nickelate. The grain production is too large, which can effectively increase the diffusion rate of lithium ions in charge and discharge over-symmetry. The water-soluble organic carbon source is used to make the carbon source more uniformly coated on the surface of the particle, and the organic material has a high conductivity nanocarbon coating layer formed by sintering pyrolysis, thereby improving the conductivity of the material and improving the nickel acid. Lithium cycle stability.

detailed description

In order to make the technical means, the creative features, the workflow, and the method of use of the present invention easy to understand and understand, the present invention will be further described below in conjunction with specific embodiments.

Example 1

According to n (Li): n (Ni) = 1.03, weigh 910 lithium acetate and 1000 g of nickel oxide, add 100 g of organic carbon source glucose according to the weight of 10% of nickel oxide, add nickel monoxide and glucose to add 3 L of brine-free The mixture was uniformly mixed, ball-milled for 8 hours, spray granulated, and the obtained powder was pretreated at 500 ° C for 7 h in an inert atmosphere to obtain a carbon-coated nickel oxide powder. Lithium acetate was dissolved in 3.5 L of anhydrous saline, and carbon-coated nickel oxide powder was added thereto to be uniformly stirred, ball-milled for 3 hours, and spray-granulated to obtain a dry powder. The powder was placed in a rotary kiln, sintered at 650 ° C for 8 h in an N 2 atmosphere, and further heated to 800 ° C for 5 h, cooled, sieved, and classified by gas flow to obtain a product.

The resulting product had a carbon content of 1.2%.

Example 2

According to n (Li): n (Ni) = 1.07, weigh 343g of lithium hydroxide and 1000g of nickel oxide, add 150g of organic carbon source sucrose according to the weight of 15% of nickel oxide, add nickel nitrate and sucrose to add 3.5L The mixture was uniformly mixed without brine, ball-milled for 8 hours, spray granulated, and the obtained powder was pretreated at 500 ° C for 8 hours in an inert atmosphere to obtain a carbon-coated nickel oxide powder. Lithium hydroxide was dissolved in 3.5 L of anhydrous saline, and carbon-coated nickel oxide powder was added thereto to be uniformly stirred, ball-milled for 3 hours, and spray-granulated to obtain a dry powder. Adding the powder to the rotary kiln, After sintering at 600 ° C for 8 h in an N 2 atmosphere, and then heating to 800 ° C for 4 h, cooling, sieving, gas flow classification and product.

The resulting product had a carbon content of 1.6%.

Example 3

According to n (Li): n (Ni) = 1.05, weigh 336g of lithium hydroxide and 1000g of nickel oxide, add 100g of organic carbon source polyethylene glycol according to the weight of 10% of nickel oxide, nickel niobate and polyethylene The diol was added and 3.0 L of brine-free mixture was uniformly mixed, ball-milled for 3 hours, spray granulated, and the obtained powder was pretreated at 500 ° C for 8 hours in an inert atmosphere to obtain carbon-coated nickel oxide powder. Lithium hydroxide was dissolved in 3.5 L of anhydrous saline, and carbon-coated nickel oxide powder was added thereto to be uniformly stirred, ball-milled for 3 hours, and spray-granulated to obtain a dry powder. The powder was placed in a rotary kiln, sintered at 650 ° C for 8 h in an N 2 atmosphere, and further heated to 820 ° C for 6 h, cooled, sieved, and classified by gas flow to obtain a product.

The resulting product had a carbon content of 2.3%.

Example 4

According to n(Li):n(Ni)=1.06, weigh 936g of lithium acetate and 1000g of nickel monoxide, add 150g of organic carbon source polyacrylic acid according to the weight of 15% of nickel oxide, add nickel pentoxide and polypropylene to add 3.6. L was uniformly mixed without brine, ball-milled for 8 h, spray granulated, and the obtained powder was pretreated at 500 ° C for 8 h in an inert atmosphere to obtain a carbon-coated nickel oxide powder. Lithium acetate was dissolved in 3.5 L of anhydrous saline, and carbon-coated nickel oxide powder was added thereto to be uniformly stirred, ball-milled for 3 hours, and spray-granulated to obtain a dry powder. The powder was placed in a rotary kiln, sintered at 650 ° C for 8 h in an N 2 atmosphere, heated to 880 ° C for 8 h, cooled, sieved, and classified by gas flow to obtain a product.

The resulting product had a carbon content of 2.6%.

Example 5

According to n (Li): n (Ni) = 1.04, weigh 333g of lithium hydroxide and 1000g of nickel oxide, add 100g of organic carbon source glucose according to the weight of 10% of nickel oxide, add nickel oxide and glucose to add 3.6L The mixture was uniformly mixed without brine, ball-milled for 8 hours, spray granulated, and the obtained powder was pretreated at 500 ° C for 8 hours in an inert atmosphere to obtain a carbon-coated nickel oxide powder. Lithium hydroxide was dissolved in 4.0 L of anhydrous saline, and carbon-coated nickel oxide powder was added thereto to be uniformly stirred, ball-milled for 3 hours, and spray-granulated to obtain a dry powder. The powder was placed in a rotary kiln, sintered at 650 ° C for 8 h in an N 2 atmosphere, and further heated to 880 ° C for 5 h, cooled, sieved, and classified by gas flow to obtain a product.

The resulting product had a carbon content of 2.3%.

Comparative example 1

According to n (Li): n (Ni) = 1.03, 910 lithium acetate and 1000 g of nickel oxide were weighed, added with 3 L of anhydrous brine, uniformly mixed, ball-milled for 8 h, and spray granulated to obtain a dry powder. The powder was placed in a rotary kiln, sintered at 650 ° C for 8 h in an N 2 atmosphere, and further heated to 800 ° C for 5 h, cooled, sieved, and classified by gas flow to obtain a product.

The resulting product has a carbon content of zero.

Electrochemical performance test

In order to test the performance of the lithium nickelate cathode material of the modified lithium ion battery prepared by the method of the present invention, the test was carried out by a half-cell test method using the cathode material of the above examples and comparative examples: acetylene black: PVDF (polyvinylidene fluoride) = 93:3:4 (weight ratio), adding appropriate amount of NMP (N-methylpyrrolidone) to make a slurry, coating on copper foil, drying at 110 ° C for 8 hours under vacuum to make a positive electrode sheet; The electrode and the electrolyte were 1 mol/L LiPF6/EC+DEC+DMC=1:1:1, and the polypropylene microporous membrane was a separator, which was assembled into a battery. The charge-discharge voltage is 1.0-2.5V, and the charge-discharge rate is 0.5C. The battery performance can be tested. The test results are shown in Table 1.

Table 1 compares the performance of cathode materials in different examples and comparative examples.

The basic principles and main features of the present invention and the advantages of the present invention are shown and described above, and those skilled in the art should understand that the present invention is not limited by the above embodiments, and that the above embodiments and descriptions are merely illustrative of the present invention. The present invention is subject to various modifications and improvements without departing from the spirit and scope of the invention, which fall within the scope of the invention as claimed. The requirements and their equivalents are defined.

Claims

A method for synthesizing a lithium ion positive electrode material LiNiO 2 /C, which comprises the following steps:

1) mixing nickel monoxide and an organic carbon source with water, ball milling treatment, spray granulation, and the obtained powder is pretreated in an inert atmosphere to obtain carbon coated nickel oxide powder;

2) dissolving the lithium source in water, adding the nickel niobate powder obtained in the step 1), and then ball-milling and then spray granulating to obtain a dry powder;

3) The dry powder obtained in the step 2) is treated in an inert atmosphere, and then subjected to a high-temperature heat treatment, and a lithium ion positive electrode material LiMn 2 O 4 /CLiNiO 2 /C is obtained by gas flow classification.
A method for synthesizing a lithium ion positive electrode material LiNiO 2 /C according to claim 1, wherein in the step 1), the organic carbon source is one of water-soluble organic substances, and the soluble The organic matter in water may be selected from one of glucose, sucrose, fructose, polyethylene glycol, polyacrylic acid, and chitosan.
The method for synthesizing a lithium ion positive electrode material LiNiO 2 /C according to claim 1, wherein in the step 1), the ball milling treatment time is 5 to 10 hours; and the pretreatment temperature is 400 to At 500 ° C, the pretreatment time can be 5-8 h.
The method for synthesizing a lithium ion positive electrode material LiNiO 2 /C according to claim 1, wherein in the step 2), the lithium source may be one of a water-soluble lithium salt lithium acetate and lithium hydroxide; The ball milling treatment time may be 2 to 3 hours.
A method for synthesizing a lithium ion positive electrode material LiNiO 2 /C according to claim 1, wherein in the steps 1) and 2), the nickel oxide and lithium sources may be n (Li) in terms of the number of moles of elements. : n (Ni) = 1.03 to 1.07.
A method for synthesizing a lithium ion positive electrode material LiNiO 2 /C according to claim 1, wherein in the step 1), in the step 1), the mass of the organic carbon source may be 10 of the mass of the nickel oxide. %~15%.
A method for synthesizing a lithium ion positive electrode material LiNiO 2 /C according to claim 1, wherein in steps 1) and 2), in steps 1) and 2), the water can be used without brine, wherein The amount of water added in step 1) may be 3 to 4 times that of nickel oxide, and the amount of water added in step 2) may be 3 to 4 times the mass of carbon coated nickel oxide powder.
A method of synthesizing a lithium ion positive electrode material LiNiO 2 /C according to claim 1, wherein in the steps 1) and 3), the inert atmosphere is nitrogen or argon.
The method for synthesizing a lithium ion positive electrode material LiNiO 2 /C according to claim 1, wherein in the step 3), the temperature of the treatment may be 500 to 600 ° C, and the treatment time may be 10 to 20 h; The high temperature heat treatment may be performed at a temperature of 750 to 850 ° C, and the high temperature heat treatment may be carried out for 2 to 20 hours.