CN102569750A - Cathode composite material of lithium ion battery and preparation method thereof - Google Patents

Abstract

The invention provides a lithium ion battery negative electrode composite material, including graphene and an electrode active material; the electrode active material is one of mesophase pitch carbon microspheres, silicon, lithium titanate, titanium dioxide, tin dioxide and graphite or more. In the invention, the graphene and the electrode active material are mixed with water, and the obtained mixed solution is dried to obtain the negative electrode composite material of the lithium ion battery. The present invention uses graphene as a conductive additive, graphene has good electrical conductivity, mechanical strength and huge specific surface area, it can be well attached to the surface of the electrode active material, helps to shorten the diffusion path of lithium ions, and improves the The ionic conductivity of the lithium-ion battery negative electrode composite material; and the addition of graphene can also strengthen the sufficient contact between the battery negative electrode material and the current collector, thereby better improving the cycle performance and rate performance of the lithium-ion battery. The invention provides Lithium-ion battery anode materials have good electrical properties.

Description

Lithium-ion battery negative electrode composite material and preparation method thereof

technical field

The invention relates to the technical field of lithium battery electrodes, in particular to a lithium ion battery negative electrode composite material and a preparation method thereof.

Background technique

Today, with the rapid development of information technology and the increasing emphasis on environmental protection, the development of chemical power sources is facing greater challenges. Lithium-ion batteries have been greatly developed because of their advantages such as high energy density, high output voltage, long service life, good cycle performance, low self-discharge rate, no memory effect and good environmental performance. It has been widely used in electronic products such as mobile phones, notebook computers, cameras, vehicles such as electric vehicles and electric bicycles, aerospace vehicles such as airplanes, satellites and spaceships, and military equipment such as warships and submarines. It is widely used and has broad development prospects.

The development of consumer electronics, electric vehicles and energy storage has put forward higher requirements for the energy density, power density, cycle times and safety of lithium-ion batteries. Among them, the improvement of lithium-ion battery anode materials is to improve its performance. One of the key points is also a hot and difficult point of research. At present, in commercial production, mesophase carbon microspheres, as electrode active materials, have high lithium storage capacity and good voltage platform, and have been widely used in lithium-ion battery anode materials. However, the spherical particles of mesophase carbon microspheres contact each other in a point-to-point manner, resulting in less contact surface and poor contact effect, resulting in low conductivity, and it will also affect the lithium ion in the process of high-current charge and discharge. Therefore, this kind of mesophase carbon microspheres is not suitable for the use of high-rate charge and discharge as the negative electrode material of lithium-ion batteries, and is far from meeting the development requirements of power lithium-ion batteries.

In order to improve the rate performance of lithium-ion batteries, conductive carbon black is often added to the electrode active material in the prior art. However, due to the point contact between the traditional conductive carbon black and the active material, it cannot form a good conductive network. In the case of high-current charging and discharging, its specific capacity drops rapidly, which also cannot meet the development requirements of power lithium-ion batteries. In 1991, Japanese expert Iijima (Iijima) discovered carbon nanotubes (CNTs). CNTs have good axial one-dimensional conductivity. YZHANG et al. found that one CNT can act as hundreds to thousands of carbon blacks. The conduction distance achieved by the particles, its fibrous structure can maintain the conductive network during the cycle, improve the utilization rate of the electrode active material and improve the rate discharge capacity of the electrode (Y ZHANG, XG ZHANG, HL ZHANG, et al.Composite anode material of silicon/graphite/carbon nanotubes for Li-ion batteries[J]. Electrochem Acta, 2006, 51: 4994～5000.).

The lithium-ion battery negative electrode composite material reported in the above literature with CNTs as conductive additive has better electrode rate discharge ability than conductive carbon black as conductive additive, but the rate performance of this lithium-ion battery negative electrode composite material is still low. , still cannot meet the development needs of power lithium-ion batteries, thus limiting the application of lithium-ion batteries.

Contents of the invention

The purpose of the present invention is to provide a lithium-ion battery negative electrode composite material and a preparation method thereof. The lithium-ion battery negative electrode composite material provided by the present invention has a higher rate performance, which is beneficial to the application of lithium-ion batteries.

The invention provides a lithium ion battery negative electrode composite material, including graphene and electrode active materials;

The electrode active material is one or more of mesophase pitch carbon microspheres, silicon, lithium titanate, titanium dioxide, tin dioxide and graphite.

Preferably, the particle size of the graphene is 4 μm˜30 μm.

Preferably, the mass ratio of the graphene to the electrode active material is 1: (1-100).

Preferably, the mass ratio of the graphene to the electrode active material is 1: (10-50).

Preferably, the electrode active material is one or more of mesophase pitch carbon microspheres, silicon, lithium titanate and tin dioxide.

The present invention provides a kind of preparation method of negative electrode composite material of lithium ion battery, comprises the following steps:

Mixing graphene, electrode active material and water to obtain a mixed solution;

Drying the mixed solution to obtain a lithium-ion battery negative electrode composite material;

The electrode active material is one or more of mesophase pitch carbon microspheres, silicon, lithium titanate, titanium dioxide, tin dioxide and graphite.

Preferably, the graphene, electrode active material and water are mixed, specifically:

Grinding the graphene and the electrode active material to obtain the ground graphene and the electrode active material;

Under ultrasonic conditions, the ground graphene is mixed with electrode active materials and water.

Preferably, the drying is spray drying or freeze drying.

Preferably, the spray drying temperature is 150°C-300°C.

Preferably, the freeze-drying temperature ranges from -20°C to 60°C.

The invention provides a lithium ion battery negative electrode composite material, including graphene and electrode active materials; the electrode active materials are one or more of intermediate pitch carbon microspheres, silicon, lithium titanate, titanium dioxide, tin dioxide and graphite Various. In the invention, the graphene, the electrode active material are mixed with water and then dried to obtain the lithium ion battery negative electrode composite material. The lithium-ion battery negative electrode composite material provided by the present invention includes graphene, which has good electrical conductivity, mechanical strength and huge specific surface area, and the organic combination with the active material can increase the contact area between graphene and electrode active materials. It helps to shorten the diffusion path of lithium ions and improve its ionic conductivity. At the same time, the addition of graphene can also strengthen the full contact between the battery negative electrode material and the current collector, thereby effectively improving the cycle performance and rate performance of lithium-ion batteries; In addition, Graphene can be well attached to the surface of the electrode active material, avoiding the separation and shedding of the electrode active material caused by the volume expansion or contraction of the electrode active material during charging and discharging, and increasing its service life. Experimental results show that after 50 charge-discharge cycles at a rate of 0.1C, the specific capacity of the lithium-ion battery negative electrode composite material provided by the invention remains at about 90%; The specific capacity decay of the lithium ion battery negative electrode composite material provided by the invention is relatively slow, and the rate performance is good; the lithium ion battery negative electrode composite material provided by the invention can still maintain its specific capacity above 60% after 2 years of use.

In addition, the preparation method of the negative electrode composite material of the lithium ion battery provided by the present invention is simple, the raw materials are easily obtained, the production cost is reduced, and it is beneficial to the wide application of the lithium ion battery.

Description of drawings

Fig. 1 is the SEM image of the negative electrode composite material of lithium ion battery prepared by the embodiment of the present invention 1;

Fig. 2 is the discharge specific capacity figure of the negative electrode composite material of lithium ion battery prepared by the embodiment of the present invention 1 and comparative example,

Wherein, curve 1 is the discharge specific volume diagram of the lithium ion battery negative electrode composite material prepared in Example 1 of the present invention, and curve 2 is the discharge specific volume diagram of the lithium ion battery negative electrode composite material prepared in the comparative example of the present invention;

Fig. 3 is the discharge rate performance figure of the negative electrode composite material of lithium ion battery prepared by the embodiment of the present invention 1 and comparative example,

Wherein, curve 1 is the discharge rate performance curve of the lithium ion battery negative electrode composite material prepared in Example 1 of the present invention, and curve 2 is the discharge rate performance curve of the lithium ion battery negative electrode composite material prepared in the comparative example of the present invention;

Fig. 4 is a SEM image of the negative electrode composite material of lithium ion battery prepared in Example 2 of the present invention.

Detailed ways

The invention provides a lithium ion battery negative electrode composite material, including graphene and electrode active materials;

The electrode active material is one or more of mesophase pitch carbon microspheres, silicon, lithium titanate, titanium dioxide, tin dioxide and graphite.

Lithium-ion battery refers to a battery system that uses two different lithium intercalation compounds that can reversibly intercalate and deintercalate lithium ions as the positive and negative electrodes of the battery, respectively. It is a rechargeable battery that primarily relies on the movement of lithium ions between the positive and negative electrodes to function. When charging, lithium ions are deintercalated from the positive electrode, passed through the electrolyte and separator, and inserted into the negative electrode; on the contrary, lithium ions are deintercalated from the negative electrode, passed through the electrolyte and separator, and inserted into the positive electrode. The negative electrode material of the battery is the main component of the lithium-ion battery, and the performance of the negative electrode material directly affects the performance of the lithium-ion battery.

The lithium ion battery negative electrode composite material provided by the invention includes graphene. Graphene was obtained by Geim et al., a professor of physics at the University of Manchester in 2004, by using adhesive tape to peel off highly oriented graphite. Graphene has the characteristics of atomic-scale thickness, huge specific surface area, good thermal conductivity and electron transport performance, high mechanical strength and stability. The lithium-ion battery negative electrode composite material provided by the present invention includes graphene. Since graphene has a perfect two-dimensional structure, it can be organically combined with the electrode active material, making the contact between it and the electrode active material The area is greatly increased, which helps to shorten the diffusion path of lithium ions, improves its ion conductivity, and strengthens the full contact between the electrode active materials and the negative electrode composite material of the battery and the current collector, thereby improving the efficiency of lithium ions. The rate performance and cycle performance of the battery negative electrode composite material; graphene can be well attached to the surface of the electrode active material, avoiding the separation and shedding of the electrode active material caused by the volume expansion and shrinkage of the electrode active material during charge and discharge , thereby prolonging the service life of the lithium-ion battery.

The present invention has no special restrictions on the technical parameters of the graphene, such as particle size, specific surface area and electrical conductivity, and the graphene well-known to those skilled in the art can be used. In the present invention, the particle size of the graphene is preferably 4 μm to 30 μm, more preferably 6 μm to 25 μm; the specific surface area of the graphene is preferably 120 m ² /g to 200 m ² /g, more preferably 135 m ^{2 /g} g˜170 m ² /g; the electrical conductivity of the graphene is preferably 600 S/cm˜900 S/cm, more preferably 680 S/cm˜800 S/cm.

The lithium-ion battery negative electrode composite material provided by the present invention includes electrode active materials. The present invention has no special restrictions on the electrode active materials, and the electrode active materials known to those skilled in the art as lithium-ion battery negative electrode materials can be used. In the present invention, the electrode active material is one or more of mesophase pitch carbon microspheres, silicon, lithium titanate, titanium dioxide, tin dioxide and graphite, preferably mesophase pitch carbon microspheres, silicon, One or more of lithium titanate and tin dioxide, more preferably one of mesophase pitch carbon microspheres, silicon, lithium titanate and tin dioxide, the graphite is preferably artificial graphite and natural graphite one or both. In the lithium-ion battery negative electrode composite material provided by the present invention, the mass ratio of the graphene to the electrode active material is preferably 1: (1-100), more preferably 1: (10-50), most preferably 1: (15-45).

The invention provides a lithium ion battery negative electrode composite material, including graphene and an electrode active material; the electrode active material is one of mesophase pitch carbon microspheres, silicon, lithium titanate, titanium dioxide, tin dioxide and graphite or more. The present invention uses graphene as a conductive additive. Graphene's excellent electrical conductivity, huge specific surface area, and good mechanical properties make it organically combined with the electrode active material, improving the connection between the graphene and the electrode. The contact area between the active materials helps to shorten the diffusion path of lithium ions, improve its ionic conductivity, and at the same time strengthen the full contact between the battery negative electrode composite material and the current collector, and improve the cycle performance and performance of the lithium ion battery negative electrode composite material. Rate performance; at the same time, graphene can be well attached to the surface of the electrode active material, avoiding the separation and shedding of the electrode active material caused by the volume expansion and shrinkage of the electrode active material during charging and discharging, and prolonging the life of the electrode active material. The service life of the lithium-ion battery is shortened.

Experimental results show that after 50 charge-discharge cycles at a rate of 0.1C, the specific capacity of the lithium-ion battery negative electrode composite material provided by the invention remains at about 90%; The negative electrode composite material of the lithium ion battery provided by the invention has slow capacity decay and good rate performance; the negative electrode composite material of the lithium ion battery provided by the invention can still maintain a specific capacity above 60% after 2 years of use.

The present invention provides a kind of preparation method of negative electrode composite material of lithium ion battery, comprises the following steps:

Mixing graphene, electrode active material and water to obtain a mixed solution;

Drying the mixed solution to obtain a lithium-ion battery negative electrode composite material;

The electrode active material is one or more of mesophase pitch carbon microspheres, silicon, lithium titanate, titanium dioxide, tin dioxide and graphite.

The invention firstly mixes graphene, electrode active material and water to obtain a mixed solution. In the present invention, before mixing the graphene, the electrode active material and water, the graphene and the electrode active material are preferably ground to obtain the ground graphene and the electrode active material, preferably under ultrasonic conditions, the obtained The ground graphene is mixed with electrode active material and water. The present invention has no special limitation on the parameters of the grinding, and the technical solution of grinding well known to those skilled in the art can be adopted. In the present invention, the particle size of the graphene is preferably 4 μm to 30 μm, more preferably 6 μm to 25 μm; the specific surface area of the graphene is preferably 120 m ² /g to 200 m ² /g, more preferably 135 m ^{2 /g} g～170m ² /g; the conductivity of the graphene is preferably 600S/cm～900S/cm, more preferably 680S/cm～800S/cm; the electrode active material is mesophase pitch carbon microspheres, silicon, One or more of lithium titanate, titanium dioxide, tin dioxide and graphite, preferably one or more of mesophase pitch carbon microspheres, silicon, lithium titanate and tin dioxide, more preferably mesophase One of pitch carbon microspheres, silicon, lithium titanate and tin dioxide, the graphite is preferably one or both of artificial graphite or natural graphite; the mass ratio of the graphene to the electrode active material Preferably it is 1:(1-100), more preferably 1:(10-50), most preferably 1:(15-45).

To obtain the ground graphene and the electrode active material, the present invention preferably mixes the ground graphene, the electrode active material and water under ultrasonic conditions, preferably to obtain a uniform mixed solution. The present invention has no special limitation on the parameters of the ultrasound, such as temperature, time, etc., and the technical solutions of ultrasound well known to those skilled in the art can be used. In the present invention, the water is preferably deionized water, and the ratio of the quality of the water to the total mass of the graphene and the electrode active material is preferably 100: (0.5-10), more preferably 100: (1-5), most preferably 100:(2-3).

After the mixed solution is obtained, the present invention dries the mixed solution to obtain the lithium ion battery negative electrode composite material. The present invention has no special requirements on the drying parameters, such as temperature, time, etc., and the drying technical solutions well known to those skilled in the art can be adopted. In the present invention, the drying is preferably spray drying or freeze drying, more preferably spray drying; the spray drying temperature is preferably 150°C to 300°C, more preferably 160°C to 290°C, more preferably 180°C ~280°C; the freeze-drying temperature is preferably -20°C-60°C, more preferably -10°C-50°C; the drying time is preferably 10h-100h, more preferably 50h-80h.

The invention uses graphene and electrode active materials as raw materials, mixes them with water to obtain a mixed solution, and dries the mixed solution to obtain a lithium ion battery negative electrode composite material. The lithium ion battery negative electrode composite material provided by the invention has higher rate performance, cycle performance and service life. The preparation method of the lithium-ion battery negative electrode composite material provided by the invention has few steps, simple operation, easy-to-obtain raw materials, reduces production costs, and is beneficial to the wide application of lithium-ion batteries.

The present invention carries out scanning electron microscope (SEM) scanning analysis to the obtained negative electrode composite material of lithium ion battery, obtains the appearance characteristic of lithium ion battery negative electrode composite material, the result shows that in the lithium ion battery negative electrode composite material provided by the invention, graphene It is well attached to the surface of the electrode active material, and the contact area between the graphene and the electrode active material is obviously increased.

The present invention tests the electrical properties of the obtained lithium-ion battery negative electrode composite material, and the results show that the lithium-ion battery negative electrode composite material provided by the present invention is charged and discharged 50 times at a rate of 0.1C, and its specific capacity is still maintained at the initial ratio. About 90% of the capacity, with the increase of the charge and discharge current, at a rate of 0.5C, the specific capacity decay of the negative electrode composite material of the lithium ion battery provided by the invention is slow, and the rate performance is good.

The present invention tests the service life of the obtained negative electrode composite material of lithium ion battery, and the result shows that the specific capacity of the negative electrode composite material of lithium ion battery provided by the present invention can still be kept above 60% after being used for 2 years.

The invention provides a lithium ion battery negative electrode composite material, including graphene and an electrode active material; the electrode active material is one of mesophase pitch carbon microspheres, silicon, lithium titanate, titanium dioxide, tin dioxide and graphite or more. In the invention, the graphite is mixed with the electrode active material and water, and the obtained mixed solution is dried to obtain the negative electrode composite material of the lithium ion battery. The lithium ion battery negative electrode composite material provided by the present invention includes graphene, and its huge specific surface area enhances the contact between graphene and the electrode active material, which is beneficial to the transmission of lithium ions, and it also has better electrical conductivity , improve the ionic conductivity, and at the same time strengthen the contact between the battery negative electrode material and the current collector, improve the cycle performance and rate performance of the battery negative electrode composite material; at the same time, graphene can be well attached to the electrode active material, effectively The separation and shedding of the electrode active material caused by the volume expansion and shrinkage of the electrode active material during the charging and discharging process are avoided, thereby prolonging its service life. In addition, the method provided by the present invention is simple, and the graphene is mixed with the electrode active material in an ultrasonic manner, so that the mixture between the graphene and the electrode active material is more uniform, and the negative electrode of the lithium ion battery is further improved. properties of composite materials. The preparation method provided by the invention has easy-to-obtain raw materials, reduces production costs, and is beneficial to the wide application of lithium-ion batteries.

In order to further illustrate the present invention, the lithium-ion battery negative electrode composite material provided by the present invention and its preparation method are described in detail below in conjunction with the examples, but they should not be understood as limiting the protection scope of the present invention.

Example 1

Mix 0.1g of graphene with a particle size of about 10μm, a specific surface area of 153m ² /g, and a conductivity of 712S/cm with 10g of mesophase pitch carbon microspheres, grind them evenly, add 1010mL of deionized water to it, and ultrasonically disperse Obtain a uniformly mixed mixed solution; join the mixed solution into a spray dryer, control the flow rate of the mixed solution to be 3mL/min, the temperature at the feed inlet is 150°C, and the temperature at the outlet is 50°C. Lithium-ion battery anode composite material.

The present invention carries out scanning electron microscope (SEM) scanning analysis to the negative electrode composite material of lithium ion battery obtained, and the result is as shown in Figure 1, and Fig. 1 is the SEM image of the negative electrode composite material of lithium ion battery prepared by Example 1 of the present invention, by Fig. 1 It can be seen that graphene is well attached to the surface of mesophase pitch carbon microspheres, and the contact between graphene and mesophase pitch carbon microspheres is surface contact, and the contact area is greatly increased.

The present invention tests the electrical properties of the lithium-ion battery negative electrode composite material obtained, and the results are as shown in Figure 2 and Figure 3, and Figure 2 is the lithium-ion battery negative electrode composite material prepared by Example 1 of the present invention and comparative example at 0.1C current The discharge specific capacity diagram under the density, as can be seen from Figure 2, the first reversible capacity of the lithium-ion battery negative electrode composite material prepared in this example is as high as 330mAh/g, and it can be cycled 50 times under the 0.1C rate (1C=330mAh/g) After that, its discharge specific capacity can still be kept at 280mAh/g, which is far higher than the capacity of the lithium ion battery negative electrode composite material prepared by comparative example; Fig. 3 is the lithium ion battery negative electrode composite prepared by embodiment 1 of the present invention and comparative example The discharge rate performance diagram of the material, as can be seen from Figure 3, under the discharge condition of 0.1C～0.2C rate, the discharge rate of the lithium ion battery negative electrode composite material prepared in Example 1 and the lithium ion battery negative electrode composite material prepared in Comparative Example The specific capacity is similar. After the 0.5C rate, the discharge specific capacity of the lithium ion battery negative electrode composite material prepared in Example 1 can still maintain more than 85% of the original. The results show that the lithium ion battery material obtained in this embodiment has a higher Electrical conductivity.

The present invention tests the service life of the lithium-ion battery negative electrode composite material obtained, and the results show that the lithium-ion battery negative electrode material prepared in this embodiment has a specific capacity of about 65% of the initial specific capacity after charging and discharging 200 times. This shows that the lithium ion battery negative electrode composite material provided by the present invention has a relatively high service life.

comparative example

Mix 0.1g conductive carbon black with 10g mesophase pitch carbon microspheres, grind evenly, add 40.2mL deionized water to it, obtain a uniformly mixed mixed solution after ultrasonic dispersion; add the mixed solution to a spray dryer, The flow rate of the mixed solution was controlled to be 3 mL/min, the temperature of the feed inlet was 150° C., and the temperature of the discharge outlet was 50° C., and the lithium-ion battery negative electrode composite material was obtained at the discharge outlet.

The present invention researches the electrical performance of the lithium-ion battery negative electrode composite material that comparative example obtains, and the result is as shown in Figure 2 and Figure 3, and Fig. 2 is the lithium ion battery negative electrode composite material prepared by the embodiment of the present invention 1 and comparative example at 0.1C current The discharge specific capacity figure under the density, as can be seen from Fig. 2, after the negative electrode composite material of lithium ion battery prepared by comparative example circulates 20 times, its discharge specific capacity reduces, and after 50 cycles, its discharge capacity ratio is less than 200mAh/ g; Fig. 3 is the discharge rate performance diagram of the lithium ion battery negative electrode composite material prepared by Example 1 of the present invention and comparative example, it can be possible to go out from Fig. 3, under the discharge condition of 0.1C～0.2C rate, embodiment 1 prepares The discharge specific capacity of the lithium ion battery negative electrode composite material prepared in the comparative example is similar to that of the lithium ion battery negative electrode composite material prepared in the comparative example. 50% of its initial discharge specific capacity is far lower than the discharge specific capacity of the lithium-ion battery negative electrode composite material prepared in Example 1 under the same conditions.

Example 2

Mix 1g of graphene with a particle size of about 30μm, a specific surface area of 150m ² /g, and a conductivity of 715S/cm with 50g of mesophase pitch carbon microspheres, grind them evenly, add 2550mL of deionized water to it, and obtain Mix the mixed solution uniformly; add the mixed solution into the spray dryer, control the flow rate of the mixed solution to be 6mL/min, the temperature at the inlet is 200°C, the temperature at the outlet is 80°C, at the outlet Lithium-ion battery negative electrode composite materials are obtained everywhere.

The present invention carries out scanning electron microscope (SEM) scanning analysis to the negative electrode composite material of lithium ion battery obtained, and the result is as shown in Figure 4, and Fig. 4 is the SEM image of the negative electrode composite material of lithium ion battery prepared by Example 2 of the present invention, by Fig. 4 It can be seen that graphene is well attached to the surface of mesophase pitch carbon microspheres, and the contact between graphene and mesophase pitch carbon microspheres is surface contact, and the contact area is greatly increased.

The present invention tests the electrical properties of the obtained lithium-ion battery negative electrode composite material, and the results show that the first reversible capacity of the lithium-ion battery negative electrode composite material obtained in this embodiment is as high as 340mAh/g, and after 50 cycles at a rate of 0.1C, Its capacity can be maintained at 280mAh/g; at a rate of 0.5C, the discharge specific capacity of the lithium-ion battery negative electrode composite material obtained in this embodiment can still maintain more than 90% of the original. This shows that the lithium ion battery negative electrode composite material provided by the present invention has excellent rate performance.

The present invention tests the service life of the lithium-ion battery negative electrode composite material obtained, and the results show that the lithium-ion battery negative electrode material prepared in this embodiment has a specific capacity of about 68% of the initial specific capacity after charging and discharging 200 times. This shows that the lithium ion battery negative electrode composite material provided by the present invention has a relatively high service life.

Example 3

Mix 1g of graphene with a particle size of about 30μm, a specific surface area of 150m ² /g, and a conductivity of 715S/cm with 50g of lithium titanate powder, grind it evenly, add 2550mL of deionized water to it, and obtain a uniform mixture after ultrasonic dispersion The mixed solution; the mixed solution is added to the spray dryer, the flow rate of the mixed solution is controlled to be 6mL/min, the temperature of the feed inlet is 200 ° C, the temperature of the discharge port is 80 ° C, and the mixture is obtained at the discharge port. Lithium-ion battery anode composite material.

The present invention carries out scanning electron microscope (SEM) scanning analysis to the obtained negative electrode composite material of lithium ion battery, and the result shows that in the negative electrode composite material of lithium ion battery prepared in this embodiment, graphene is well attached to the surface of lithium titanate, The contact between graphene and lithium titanate is surface contact, and its contact area has been greatly increased.

The present invention tests the electrical properties of the obtained lithium-ion battery negative electrode composite material, and the results show that the first reversible capacity of the lithium-ion battery negative electrode composite material obtained in this embodiment is as high as 220mAh/g, and after 50 cycles at a rate of 0.1C, Its capacity can be maintained at 200mAh/g; when cycled at 1C rate for 100 times, the discharge specific capacity of the lithium-ion battery negative electrode composite material obtained in this embodiment can still maintain 170mAh/g. This shows that the lithium ion battery negative electrode composite material provided by the present invention has excellent rate performance.

The present invention tests the service life of the lithium-ion battery negative electrode composite material obtained, and the results show that the lithium-ion battery negative electrode material prepared in this embodiment has a specific capacity of about 62% of the initial specific capacity after charging and discharging 200 times. This shows that the lithium ion battery negative electrode composite material provided by the present invention has a relatively high service life.

Example 4

Mix 1g of graphene with a particle size of about 5μm, a specific surface area of 160m ² /g, and a conductivity of 720S/cm with 10g of mesophase pitch carbon microspheres, grind them evenly, add 550mL of deionized water to it, and ultrasonically disperse Obtain a uniformly mixed mixed solution; join the mixed solution into a spray dryer, control the flow rate of the mixed solution to be 10mL/min, the temperature at the feed inlet is 300°C, and the temperature at the discharge port is 100°C. The lithium-ion battery negative electrode composite material is obtained at the mouth.

The present invention carries out scanning electron microscope (SEM) scanning analysis to the obtained negative electrode composite material of lithium ion battery, and the result shows that, in the negative electrode composite material of lithium ion battery prepared in this embodiment, graphene is well attached to mesophase pitch carbon microspheres The contact between graphene and mesophase pitch carbon microspheres is surface contact, and the contact area has been greatly increased.

The present invention tests the electrical properties of the obtained lithium-ion battery negative electrode composite material, and the results show that the first reversible capacity of the lithium-ion battery negative electrode composite material prepared in this embodiment is as high as 350mAh/g, and after 50 cycles at a rate of 0.1C, Its capacity can be maintained as 290mAh/g; At 0.5C, the discharge specific capacity of the lithium ion battery negative electrode composite material prepared in this embodiment can still maintain more than 90% of the original, which shows that the lithium ion battery negative electrode composite provided by the present invention The material has high electrical conductivity.

The present invention tests the service life of the lithium-ion battery negative electrode composite material obtained, and the results show that the lithium-ion battery negative electrode material prepared in this embodiment has a specific capacity of about 60% of the initial specific capacity after charging and discharging 200 times. This shows that the lithium ion battery negative electrode composite material provided by the present invention has a relatively high service life.

Example 5

Grind 1g of graphene with a particle size of about 5μm, a specific surface area of 160m ² /g, and a conductivity of 720S/cm and 10g of nano-silicon powder, and then add 550mL of deionized water to it, and obtain a uniform mixture after ultrasonic dispersion. Mixed solution; the mixed solution is added to the spray dryer, the flow rate of the mixed solution is controlled to be 10mL/min, the temperature of the inlet is 300°C, the temperature of the outlet is 100°C, and lithium is obtained at the outlet Ion battery anode composite material.

The present invention carries out scanning electron microscope (SEM) scanning analysis to the negative electrode composite material of lithium ion battery obtained, and the result shows, in the negative electrode composite material of lithium ion battery prepared in the present embodiment, graphene is well attached to the surface of nano-silicon, graphite The contact between alkene and nano-silicon is surface contact, and its contact area has been greatly increased.

The present invention tests the electrical properties of the obtained lithium-ion battery negative electrode composite material, and the results show that the first reversible capacity of the lithium-ion battery negative electrode composite material prepared in this embodiment is as high as 1200mAh/g, and after 50 cycles at a rate of 0.1C, Its capacity can be maintained as 900mAh/g; After 510 cycles at 1C, the discharge specific capacity of the lithium ion battery negative electrode composite material prepared in this embodiment can still be as high as 800mAh/g, which shows that the lithium ion battery negative electrode composite provided by the present invention The material has high electrical conductivity.

The present invention tests the service life of the lithium-ion battery negative electrode composite material obtained, and the results show that the lithium-ion battery negative electrode material prepared in this embodiment has a specific capacity of about 63% of the initial specific capacity after charging and discharging 200 times. This shows that the lithium ion battery negative electrode composite material provided by the present invention has a relatively high service life.

Example 6

Mix 1g of graphene with a particle size of about 18μm, a specific surface area of 153m ² /g, and a conductivity of 712S/cm with 5g of mesophase pitch carbon microspheres, grind them evenly, add 150mL of deionized water to it, and ultrasonically disperse Obtain a uniformly mixed mixed solution; join the mixed solution into a spray dryer, control the flow rate of the mixed solution to be 5mL/min, the temperature at the feed inlet is 250°C, and the temperature at the discharge port is 100°C. The lithium-ion battery negative electrode composite material is obtained at the mouth.

The present invention carries out scanning electron microscope (SEM) scanning analysis to the obtained lithium ion battery negative electrode composite material, and the result shows, in the lithium ion battery negative electrode composite material prepared by the present embodiment, graphene is well attached to the mesophase pitch carbon microsphere On the surface, the contact between graphene and mesophase pitch carbon microspheres is surface contact, and the contact area has been greatly increased.

The present invention tests the electrical properties of the obtained lithium-ion battery negative electrode composite material, and the results show that the first reversible capacity of the lithium-ion battery negative electrode composite material prepared in this embodiment is as high as 345mAh/g, and after 50 cycles at a rate of 0.1C, Its capacity can be maintained as 285mAh/g; At 0.5C, the discharge specific capacity of the lithium ion battery negative electrode composite material prepared in this embodiment can still maintain more than 90% of the original, which shows that the lithium ion battery negative electrode composite provided by the invention The material has high electrical conductivity.

The present invention tests the service life of the lithium-ion battery negative electrode composite material obtained, and the results show that the lithium-ion battery negative electrode material prepared in this embodiment has a specific capacity of about 63% of the initial specific capacity after charging and discharging 200 times. This shows that the lithium ion battery negative electrode composite material provided by the present invention has a relatively high service life.

Example 7

Grind 1g of graphene with a particle size of about 18μm, a specific surface area of 153m ² /g, and a conductivity of 712S/cm and 5g of tin dioxide powder, and then add 150mL of deionized water to it, and obtain a uniform mixture after ultrasonic dispersion. The mixed solution; the mixed solution is added to the spray dryer, the flow rate of the mixed solution is controlled to be 5mL/min, the temperature of the inlet is 250°C, the temperature of the outlet is 100°C, and the Lithium-ion battery anode composite material.

The present invention carries out scanning electron microscope (SEM) scanning analysis to the obtained negative electrode composite material of lithium ion battery, and the result shows that, in the negative electrode composite material of lithium ion battery prepared in this embodiment, graphene is well attached to the surface of tin dioxide, The contact between graphene and tin dioxide is surface contact, and its contact area has been greatly increased.

The present invention tests the electrical properties of the obtained lithium-ion battery negative electrode composite material, and the results show that the first reversible capacity of the lithium-ion battery negative electrode composite material prepared in this embodiment is as high as 900mAh/g, and after 50 cycles at a rate of 0.1C, Its capacity can be maintained at 850mAh/g; at 0.5C, the discharge specific capacity of the lithium ion battery negative electrode composite material prepared in this embodiment can still be maintained at 750mAh/g, which shows that the lithium ion battery negative electrode composite provided by the present invention The material has high electrical conductivity.

The present invention tests the service life of the lithium-ion battery negative electrode composite material obtained, and the results show that the lithium-ion battery negative electrode material prepared in this embodiment has a specific capacity of about 60% of the initial specific capacity after charging and discharging 200 times. This shows that the lithium ion battery negative electrode composite material provided by the present invention has a relatively high service life.

Example 8

Mix 1 g of graphene with a particle size of about 5 μm to 10 μm, a specific surface area of 165 m ² /g, and a conductivity of 750 S/cm with 10 g of mesophase pitch carbon microspheres, grind them evenly, add 220 mL of deionized water to it, and ultrasonically disperse Finally, a uniformly mixed mixed solution is obtained; the mixed solution is cooled to a frozen state with liquid nitrogen, and then placed in a freeze dryer, and the temperature in the freeze dryer is controlled at -10°C, and freeze-dried under vacuum conditions , after the temperature in the freeze dryer rises to 5° C., the lithium-ion battery negative electrode composite material is obtained.

The present invention carries out SEM scanning analysis to the obtained negative electrode composite material of lithium ion battery, and the result shows that graphene is well attached to the surface of mesophase pitch carbon microspheres, and the contact between graphene and mesophase pitch carbon microspheres is surface The contact area has been greatly improved.

The present invention tests the electrical properties of the obtained lithium-ion battery negative electrode composite material, and the results show that the lithium-ion battery negative electrode composite material obtained in this embodiment has an initial capacity as high as 345mAh/g, after 50 cycles at a rate of 0.1C , its capacity can still be maintained at 297mAh/g; at a rate of 0.5C, the discharge specific capacity of the lithium-ion battery negative electrode composite material obtained in this embodiment can still maintain more than 90% of the original. This shows that the lithium ion battery negative electrode composite material provided by the present invention has excellent rate performance.

The present invention tests the service life of the lithium-ion battery negative electrode composite material obtained, and the results show that the lithium-ion battery negative electrode material prepared in this embodiment has a specific capacity of about 62% of the initial specific capacity after charging and discharging 200 times. This shows that the lithium ion battery negative electrode composite material provided by the present invention has a relatively high service life.

As can be seen from the above examples, the lithium ion battery negative electrode composite material provided by the present invention includes graphene and electrode active materials, and the electrode active materials are mesophase pitch carbon microspheres, silicon, lithium titanate, titanium dioxide, tin dioxide and graphite one or more of. After the graphene is mixed with the electrode active material, deionized water is preferably added thereto, and then the obtained mixed solution is dried to obtain a lithium ion battery negative electrode composite material. The lithium-ion battery negative electrode composite material provided by the present invention uses graphene to modify the electrode active material, and the excellent electrochemical properties of graphene endow the lithium-ion battery negative electrode composite material with superior electrical properties, making it have a higher discharge specific capacity Moreover, graphene can be well attached to the electrode active material, which avoids the separation and shedding of the electrode active material caused by the volume expansion or contraction of the electrode active material during charging and discharging, and increases its service life. Further, the preparation method of the lithium ion battery negative electrode composite material provided by the present invention is preferably under the condition of ultrasound, the raw materials are mixed, so that the graphene and the electrode active material are fully mixed, and the lithium ion battery negative electrode composite material is further improved. performance. The method provided by the invention is simple to operate and is beneficial to the application of lithium ion batteries.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. A lithium-ion battery negative electrode composite material, comprising graphene and electrode active materials; The electrode active material is one or more of mesophase pitch carbon microspheres, silicon, lithium titanate, titanium dioxide, tin dioxide and graphite. 2 . The lithium ion battery negative electrode composite material according to claim 1 , wherein the particle size of the graphene is 4 μm˜30 μm. 3 . 3. The lithium-ion battery negative electrode composite material according to any one of claims 1 or 2, wherein the mass ratio of the graphene to the electrode active material is 1: (1-100). 4. The lithium-ion battery negative electrode composite material according to claim 3, wherein the mass ratio of the graphene to the electrode active material is 1: (10-50). 5. The lithium ion battery negative electrode composite material according to claim 1, wherein the electrode active material is one or more of mesophase pitch carbon microspheres, silicon, lithium titanate and tin dioxide. 6. A preparation method of lithium-ion battery negative electrode composite material, comprising the following steps: Mixing graphene, electrode active material and water to obtain a mixed solution; Drying the mixed solution to obtain a lithium-ion battery negative electrode composite material; The electrode active material is one or more of mesophase pitch carbon microspheres, silicon, lithium titanate, titanium dioxide, tin dioxide and graphite. 7. preparation method according to claim 6, is characterized in that, described graphene, electrode active material are mixed with water, specifically: Grinding the graphene and the electrode active material to obtain the ground graphene and the electrode active material; Under ultrasonic conditions, the ground graphene is mixed with electrode active materials and water. 8. The preparation method according to any one of claims 6 or 7, characterized in that the drying is spray drying or freeze drying. 9. The preparation method according to claim 8, characterized in that, the spray drying temperature is 150°C-300°C. 10. The preparation method according to claim 8, characterized in that the freeze-drying temperature is -20°C to 60°C.

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