CN102136567B - Preparing method of tin-nickel-carbon composite cathode material of lithium ion battery - Google Patents

Abstract

The invention discloses a preparation method of a tin-nickel-carbon composite negative electrode material for a lithium ion battery, which belongs to the technical field of lithium ion batteries, and uses an electrodeposition process to prepare a tin-nickel-carbon composite negative electrode material for a lithium ion battery; the electrodeposition process is: process ( 1) Graphite powder → chemically modify the surface of the graphite powder → add to the pyrophosphate alloy plating solution → ultrasonically disperse the pyrophosphate alloy plating solution added to the graphite powder; process (2) Copper foil current collector →Activation treatment; process (3) uses the copper foil current collector obtained in process (2) as the cathode, uses the hard graphite plate as the anode, and uses the plating solution obtained in process (1) as the electrolyte to perform electrodeposition coating, and finally obtains Composite coating. Compared with the prior art, the preparation method of a tin-nickel-carbon composite negative electrode material for a lithium ion battery of the present invention uses electrodeposition to prepare the tin-nickel-carbon composite negative electrode material, which has the advantages of low cost, simple preparation process, excellent electrochemical performance and long service life. Features.

Description

A preparation method of tin-nickel-carbon composite negative electrode material for lithium ion battery

technical field

The invention relates to the technical field of lithium-ion batteries, in particular to a method for preparing a tin-nickel-carbon composite negative electrode material for lithium-ion batteries. the

Background technique

Due to the shortage of energy and the increasingly serious urban environmental pollution, it is an urgent social problem that the world is facing to find an alternative energy source that replaces oil, is environmentally friendly and clean, and solves urban air pollution. Advanced electric vehicles are recognized as the future It is the most important way to develop energy-saving, environment-friendly and green transportation. At present, the electric vehicles and hybrid vehicles that are competing to develop in various countries need batteries to provide power. As the supporting power supply of electric vehicles, the outstanding performance of lithium-ion batteries has unique advantages. Positive and negative active materials in batteries and electrode preparation technology are the key to controlling the performance of lithium-ion batteries, which has become the consensus of researchers at home and abroad. the

Graphite powder has become the main body of current lithium battery anode materials due to its relatively simple processing technology, low cost, good lithium ion storage capacity and cycle charge and discharge capacity. However, the theoretical specific capacity of graphite powder is small, the capacity decay rate is large, and the high-rate charge-discharge performance is poor, prompting people to seek more excellent lithium-ion battery anode materials. From the perspective of electrode preparation technology, the coating and rolling method is mainly used in large-scale production. This process is simple and low in cost, but the coating has weak binding force on the current collector. During repeated cycles, especially in the process of high-power charging and discharging In the process, the coated negative electrode material is easy to fall off, the battery life is shortened, and the cost of use is greatly increased. the

In the past one or two years, there have been related reports on the preparation and performance research of oxide anode materials, tin alloys and tin alloy-carbon composite anodes at home and abroad. The synthesis methods include solid-phase method, chemical reduction method, low-pressure gas-phase method, and sol-gel method. and electrodeposition methods. Among them, the electrodeposition method is simple in process, easy to scale, and has a strong combination with the current collector, which has important research value. However, the current electrodeposition process specification is unstable, and the carbon content in the coating is low, so it is difficult to be applied. the

To sum up, at present, the main body of the negative electrode material is still graphite powder. The research and development of the tin-nickel/graphite composite negative electrode preparation process and its electrochemical performance with higher charge storage capacity and cycle performance and good combination with the current collector is the key to realize An important way for high-power charging and discharging of lithium batteries. the

Contents of the invention

The technical task of the present invention is to provide a tin-nickel-carbon composite negative electrode material for lithium-ion batteries that uses electrodeposition to prepare tin-nickel-carbon composite negative electrode materials, has low cost, simple preparation process, excellent electrochemical performance, and long service life. Preparation method of negative electrode material. the

The technical solution adopted by the present invention to solve its technical problems is: use electrodeposition process to prepare tin-nickel-carbon composite negative electrode material for lithium ion battery; electrodeposition process is:

Process (1): Graphite powder → chemically modify the surface of graphite powder → add to pyrophosphate alloy bath → ultrasonically disperse the pyrophosphate alloy bath added with graphite powder;

Process (2): copper foil current collector → activation treatment;

Process (3): The copper foil current collector finally obtained in process (2) is used as a cathode, the hard graphite plate is used as an anode, and the plating solution obtained in process (1) is used as an electrolyte to perform electrodeposition coating, and finally a composite coating is obtained. the

The particle size of the graphite powder is 5-12 μm. The graphite is processed by a ball milling method to obtain graphite powder with a particle size of 5-12 μm. the

The described graphite powder→surface chemical modification treatment process of graphite powder is as follows: under the condition that the content of graphite powder in the bath is 15g·L ^-1 , 1.0～1.4g·L ^-1 of sixteen Alkyltrimethylammonium bromide, non-ionic surfactant and 4-6g·L ^-1 neutral electrolyte NaCl form a composite dispersant.

The non-ionic surfactant is added in a level of 0.8-1.0 g·L ^-1 .

The pyrophosphate alloy plating solution adopts an environment-friendly pyrophosphate system, including NiCl ₂ 50～70g·L ^-1 , SnCl ₂ 10～18g·L ^-1 , K ₄ P ₂ O ₇ 180～210g·L ^{-1 1.} Glycine 20g·L ^-1 ; the pH of the pyrophosphate alloy plating solution is 7.5-8.5.

The electrodeposited coating uses a hard graphite plate as an anode and a copper foil current collector as a cathode. During the plating process, the current density is 1-1.4A·dm ^-2 and the temperature is 55°C-60°C.

The composite coating obtained at the end has a mass percent content of 38%-56% of Sn, 27%-56% of Ni, and 6%-17% of graphite. the

Under the charging and discharging mechanism of 0.2C, the composite coating has a capacity density of more than 600mA.hg ^-1 for the first time, and a charge-discharge efficiency of 85%. After twenty cycles, the discharge capacity remains at about 250mA.hg ^-1 , and the charge-discharge efficiency Keep it at 90%.

Before the electrodeposition process, the graphite is pretreated by ball milling to obtain graphite powder with a particle size of 5-12 μm. Because the density of graphite is higher than that of the electrolyte, graphite particles will sink at a certain speed under the action of gravity, and will also be buoyant to it upwards from the electrolyte, so the particle size of graphite has an effect on graphite in the plating solution Very large, reducing the particle size of graphite is very effective in reducing the sedimentation velocity. Graphite is evenly suspended in the plating solution, which can create favorable conditions for the uniform distribution of graphite in the coating. the

Whether the graphite powder can be uniformly wetted with the plating solution is the prerequisite for realizing the co-deposition of the alloy coating and the graphite powder. The present invention screens various dispersants through orthogonal experiments and other methods, and finally determines the hexadecyl trimethyl bromide Ammonium chloride, Pingpingjia, and neutral sodium chloride form a composite dispersant, and its main function in the plating solution is to reduce the wetting angle of the graphite surface, make the graphite powder positively charged, and make the graphite powder easier to deposit on the cathode . When the graphite content in the plating solution is 15g·L ^-1 , the optimum composition of the composite dispersant is cetyltrimethylammonium bromide 1.0～1.4g·L ^-1 , non-ionic surfactant such as Pingpingjia 0.8 ～1.0g·L ^-1 , neutral electrolyte NaCl4～6g·L ^-1 . After being treated with the composite dispersant, the emulsion formed by the graphite powder and the plating solution can remain stable within 24 hours, and the surface of the powder is positively charged, which effectively realizes co-deposition of the powder and the coating. When the current density is 1.0～1.4A·dm ^-2 and the temperature is 55～60℃, graphite is used as anode and copper foil current collector is used as cathode. Ni, and 6% ~ 17% C composite coating.

The composite coating is the positive electrode, metal lithium is the negative electrode, and lithium hexafluorophosphate is used as the electrolyte to form a button lithium battery. The electrochemical performance is tested by the battery parameter tester. Under the 0.2C mechanism, the specific capacity reaches 600mA.h.g～1 for the first time. The discharge efficiency is 85%, the discharge capacity is maintained at about 250mA.h.g-1 after 20 cycles, and the charge-discharge efficiency is maintained at 90%. the

Pingpingjia: Fatty alcohol polyoxyethylene ether, leveling agent, also known as Pingpingjia, is a non-ionic surfactant. Its appearance is milky white or beige ointment. When the molecular weight is high, it is solid (it can be made into tablets according to requirements) solid), easily soluble in water, ethanol, ethylene glycol, etc., with a cloud point, and the PH value of 1% aqueous solution is neutral. It is resistant to acid, alkali, hard water, heat and heavy metal salts. It has good wetting properties, and has good emulsifying, dispersing, cleaning and other properties. the

Compared with the prior art, the preparation method of a tin-nickel-carbon composite negative electrode material for a lithium ion battery of the present invention has the following advantages: the process specification for preparing a lithium battery tin-nickel alloy-carbon composite negative electrode by electrodeposition is proposed. A solid, uniform, and stable composite coating with tin alloy as the continuous phase and graphite powder as the dispersed phase is formed on the fluid, giving full play to the dual advantages of metal and graphite powder in storing charges, improving the dense surface morphology of the alloy coating, and Form a metallurgical combination with the current collector to obtain a negative electrode with strong binding force, excellent electrochemical performance, and long life to meet the needs of high-power charging and discharging of the battery; not only the process is simple, the cost is low, and it is easy to achieve large-scale production. the

Detailed ways

A kind of preparation method of lithium-ion battery tin-nickel-carbon composite negative electrode material of the present invention, uses electrodeposition process to prepare lithium-ion battery tin-nickel-carbon composite negative electrode material; Electrodeposition process is:

Process (1): Graphite powder → chemically modify the surface of graphite powder → add to pyrophosphate alloy bath → ultrasonically disperse the pyrophosphate alloy bath added with graphite powder;

Process (2): copper foil current collector → activation treatment;

Process (3): The copper foil current collector finally obtained in process (2) is used as a cathode, the hard graphite plate is used as an anode, and the plating solution obtained in process (1) is used as an electrolyte to perform electrodeposition coating, and finally a composite coating is obtained. the

The particle size of graphite powder is 5-12 μm. The graphite is processed by a ball milling method to obtain graphite powder with a particle size of 5-12 μm. the

The surface chemical modification treatment process of graphite powder is as follows: under the condition that the content of graphite powder in the bath is 15g L ^-1 , select 1.0～1.4g L ^-1 cetyl trimethyl Ammonium, non-ionic surfactant and 4-6g·L ^-1 neutral electrolyte NaCl form a composite dispersant.

The non-ionic surfactant is added at a level of 0.8～1.0g·L ^-1 .

The pyrophosphate alloy plating solution adopts an environment-friendly pyrophosphate system, including NiCl ₂ 50～70g·L ^-1 , SnCl ₂ 10～18g·L ^-1 , K ₄ P ₂ O ₇ 180～210g·L ^-1 , glycine 20g·L ^-1 ; the pH of the pyrophosphate alloy plating solution is 7.5-8.5.

For electrodeposition coating, the hard graphite plate is used as the anode, and the copper foil current collector is used as the cathode. During the plating process, the current density is 1-1.4A·dm ^-2 , and the temperature is 55°C-60°C.

Finally, the mass percent content of the composite coating is 38%-56% of Sn, 27%-56% of Ni, and 6%-17% of graphite. the

Under the charge and discharge mechanism of 0.2C, the capacity density of the composite coating reaches more than 600mA.hg ^-1 for the first time, and the charge and discharge efficiency is 85%. After twenty cycles, the discharge capacity remains at about 250mA.hg ^-1 and the charge and discharge efficiency remains at 90 %.

Before the electrodeposition process, the graphite is pretreated by ball milling to obtain graphite powder with a particle size of 5-12 μm. Because the density of graphite is higher than that of the electrolyte, the graphite particles will sink at a certain speed under the action of gravity, and will also be buoyed upward by the electrolyte, so the particle size of graphite has an effect on graphite in the plating solution. Very large, reducing the particle size of graphite is very effective in reducing the sedimentation velocity. Graphite is evenly suspended in the plating solution, which can create favorable conditions for the uniform distribution of graphite in the coating. the

Whether the graphite powder can be uniformly wetted with the plating solution is the prerequisite for realizing the co-deposition of the alloy coating and the graphite powder. The present invention screens various dispersants through orthogonal experiments and other methods, and finally determines the hexadecyl trimethyl bromide Non-ionic surfactants such as ammonium chloride and Pingpingjia, and neutral sodium chloride form a composite dispersant. Its main function in the plating solution is to reduce the wetting angle of the graphite surface, make the graphite powder positively charged, and make the graphite Powders are easier to deposit towards the cathode. When the graphite content in the bath is 15g·L ^-1 , the optimum composition of the composite dispersant is 1.0-1.4g·L ^-1 cetyltrimethylammonium bromide, 0.8 ～1.0g·L ^-1 , neutral electrolyte NaCl4～6g·L ^-1 . After being treated with the composite dispersant, the emulsion formed by the graphite powder and the plating solution can remain stable within 24 hours, and the surface of the powder is positively charged, which effectively realizes co-deposition of the powder and the coating. When the current density is 1.0～1.4A·dm ^-2 and the temperature is 55～60℃, graphite is used as anode and copper foil current collector is used as cathode. Ni, and 6% ~ 17% C composite coating.

The composite coating is the positive electrode, metal lithium is the negative electrode, and lithium hexafluorophosphate is used as the electrolyte to form a button lithium battery. The electrochemical performance is tested by the battery parameter tester. Under the 0.2C mechanism, the specific capacity reaches 600mA.h.g～1 for the first time. The discharge efficiency is 85%, the discharge capacity is maintained at about 250mA.h.g~1 after 20 cycles, and the charge-discharge efficiency is maintained at 90%. the

Except for the technical features described in the instructions, all are known technologies by those skilled in the art. the

Claims (7)

1. A preparation method for lithium-ion battery tin-nickel-carbon composite negative electrode material is characterized in that using electrodeposition process to prepare lithium-ion battery tin-nickel-carbon composite negative electrode material; electrodeposition process is: Process (1): Graphite powder → chemically modify the surface of the graphite powder → add to the pyrophosphate alloy plating solution → ultrasonically disperse the pyrophosphate alloy plating solution added to the graphite powder; Process (2): copper foil current collector → activation treatment; Process (3): use the copper foil current collector finally obtained in process (2) as the cathode, use the hard graphite plate as the anode, and use the plating solution obtained in process (1) as the electrolyte to perform electrodeposition coating, and finally obtain a composite coating; The described graphite powder→surface chemical modification treatment process of graphite powder is as follows: under the condition that the content of graphite powder in the bath is 15g·L ^-1 , 1.0～1.4g·L ^-1 of sixteen Alkyltrimethylammonium bromide, non-ionic surfactant and 4-6g·L ^-1 neutral electrolyte NaCl form a composite dispersant. 2. The preparation method of a tin-nickel-carbon composite negative electrode material for a lithium ion battery according to claim 1, characterized in that the particle size of the graphite powder is 5-12 μm. 3. The preparation method of a tin-nickel-carbon composite negative electrode material for a lithium ion battery according to claim 2, characterized in that the graphite is processed by a ball milling method to obtain graphite powder with a particle size of 5-12 μm. 4. The preparation method of a tin-nickel-carbon composite negative electrode material for a lithium-ion battery according to claim 1, characterized in that the non-ionic surfactant is added in a level of 0.8-1.0 g·L ⁻¹ . 5. The preparation method of a tin-nickel-carbon composite negative electrode material for a lithium-ion battery according to claim 1, characterized in that its described pyrophosphate alloy plating solution adopts an environment-friendly pyrophosphate system, including NiCl ₂ 50- 70g·L ^-1 , SnCl ₂ 10-18g·L ^-1 , L ₄ P ₂ O ₇ 180-210g·L ^-1 , glycine 20g·L ^-1 ; the pH of the pyrophosphate alloy plating solution is 7.5-8.5. 6. the preparation method of a kind of lithium-ion battery tin-nickel-carbon composite negative electrode material according to claim 1 is characterized in that its described electrodeposited coating, with hard graphite plate as anode, copper foil current collector as cathode, During the plating process, the current density is 1-1.4A·dm ^-2 , and the temperature is 55°C-60°C. 7. The preparation method of a tin-nickel-carbon composite negative electrode material for a lithium-ion battery according to claim 1, characterized in that the final composite coating mass percentage is 38% to 56% of Sn, 27% to 56% of Sn Ni, 6%~17% graphite.