CN104538609B - Negative electrode composite material for lithium ion battery and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a negative electrode composite material for a lithium ion battery, which has a core-shell structure comprising a core layer and a shell layer; the core layer is a mixture of titanium dioxide and silicon dioxide, and the mass ratio of the titanium dioxide to the silicon dioxide is (0.1-10): 1; the shell layer is made of carbon materials, and accounts for 5-20% of the composite material by mass percent. According to the invention, the surfaces of titanium dioxide and silicon dioxide are coated with the carbon material, on one hand, the core layer is a mixture of titanium dioxide and silicon dioxide, the titanium dioxide and the silicon dioxide are mutually permeated, so that the volume expansion of the whole negative electrode material in the charging and discharging processes can be reduced to a certain extent, and the expansion of the negative electrode material can be limited to a certain extent by the carbon material positioned on the shell layer; on the other hand, the carbon material of the shell layer can improve the ionic conductivity and the electronic conductivity of the cathode material, and the lithium ion battery containing the composite material has excellent cycle performance and rate capability.

Description

A kind of negative electrode composite material for lithium ion battery and preparation method thereof

technical field

The invention belongs to the technical field of lithium ion batteries, and in particular relates to a negative electrode composite material for lithium ion batteries with high ion conductivity and electron conductivity and a preparation method thereof.

Background technique

Silica has been widely used as a resource that exists in large quantities on the earth, but some problems have been encountered when applying silica to the negative electrode of lithium-ion batteries. Due to the stable structure of silicon dioxide, silicon dioxide cannot effectively intercalate and extract lithium ions during the charging and discharging process of lithium-ion batteries. At the same time, ordinary silicon dioxide has no nano-mesoporous structure, and its ion conductivity and electronic conductivity are low. As a result, silica cannot exert its effective capacity. Moreover, silicon dioxide has a large volume expansion effect during charge and discharge, which easily leads to electrode cracking and pulverization, which in turn leads to rapid decline in electrode capacity, which limits the capacity improvement and cycle stability of silicon dioxide.

Studies have found that when silica has a nano-porous structure, it has good electrochemical activity and can effectively deintercalate with lithium ions. At the same time, silica/carbon composites can effectively improve its ionic conductivity and Electronic conductivity, so as to obtain a high-capacity and long-cycle silica negative electrode. At present, there are related reports that put silicon oxide and conductive agent into a high-energy ball mill to prepare a composite negative electrode material, and then reduce the silicon oxide with an alkali metal to prepare a silicon composite carbon material. However, the wear energy of the mechanical ball is high, the uniformity of the ball milling cannot be guaranteed, and the carbon material and the silicon material cannot be fused uniformly, and the carbon material is only distributed on the outer surface of the silicon material, and cannot enter the inside of the silicon material well. The electrical conductivity and electronic conductivity cannot be improved, which limits the electrochemical performance of the material.

In view of this, it is necessary to provide a negative electrode composite material for lithium-ion batteries and a preparation method thereof, the composite material has high ionic conductivity and electronic conductivity, and the lithium-ion battery comprising the composite material has an excellent cycle performance, and can avoid the serious volume expansion of the silicon negative electrode material during the charging and discharging process, which causes the active material to fall off and the cycle life to decrease rapidly, and the raw material cost used in this method is low, the preparation process is simple, and it is easy for industrial production.

Contents of the invention

One of the objectives of the present invention is to: address the deficiencies in the prior art, and provide a negative electrode composite material for lithium ion batteries, the composite material has higher ion conductivity and electronic conductivity, and the lithium ion containing the composite material The battery has excellent cycle performance, and can avoid the shortcomings of the serious volume expansion of the silicon negative electrode material during the charging and discharging process, which causes the active material to fall off and the cycle life to decrease rapidly.

A negative electrode composite material for a lithium ion battery, the composite material has a core-shell structure comprising a core layer and a shell layer;

The core layer is a mixture of titanium dioxide and silicon dioxide; or, the core layer is a composite formed of titanium dioxide and silicon dioxide; or, the core layer is a composite formed by titanium dioxide and silicon dioxide, titanium dioxide and A mixture composed of silicon dioxide, and the mass ratio of the titanium dioxide to the silicon dioxide is (0.1-10):1;

The shell layer is carbon material, and the mass percentage of the shell layer in the composite material is 5%-20%.

As an improvement of the negative electrode composite material for lithium ion batteries of the present invention, the titanium dioxide is anatase titanium dioxide, rutile titanium dioxide or brookite titanium dioxide.

As an improvement of the negative electrode composite material for lithium ion batteries of the present invention, the particle diameter of the core layer is 50 nm-2 μm, and the thickness of the shell layer is 50 nm-1 μm. The particle size of the core layer should not be too large, otherwise the diffusion path of lithium ions is too long, which will lead to the inability of lithium ions to achieve rapid intercalation and extraction, and then make the rate performance of the battery containing the negative electrode material poor. For titanium dioxide, the particle size is relatively small. Small can change its lithium intercalation capacity and rate performance; the thickness of the shell layer should not be too large, otherwise the energy density of the battery containing the negative electrode material will be reduced, and the thickness of the shell layer should not be too small, otherwise the performance of the negative electrode material cannot be improved. Ionic conductivity and electronic conductivity.

As an improvement of the negative electrode composite material for lithium ion batteries of the present invention, the micropores of the titanium dioxide and the silicon dioxide are embedded with the carbon material, and the carbon material is at least one of hard carbon, soft carbon and graphite. One, thereby effectively improving the ionic conductivity and electronic conductivity of the material.

When titanium dioxide is used as the negative electrode material, in the lithium ion intercalation/extraction process, the volume expansion is small, the intercalation/extraction depth is small, the stroke is short, the discharge platform potential is high, the safety performance is good, the first irreversible capacity loss is small, the raw material is abundant, non-toxic and harmless , no SEI film is formed during charging and discharging. However, it also has the following problems: its own conductivity is poor, and TiO ₂ particles are easy to agglomerate during the repeated lithium ion intercalation and deintercalation process, resulting in slow diffusion of lithium ions in the solid active material, and lithium ions cannot be quickly intercalated and deintercalated. Poor, which limits its application in power lithium batteries.

In the present invention, carbon materials are coated on the surface of titanium dioxide and silicon dioxide. On the one hand, the core layer is a mixture of titanium dioxide and silicon dioxide, or a composite formed of titanium dioxide and silicon dioxide, or a composite made of titanium dioxide and silicon dioxide. The formed composite, a mixture of titanium dioxide and silicon dioxide, instead of pure silicon dioxide, can reduce the volume expansion of the entire negative electrode material during the charge and discharge process, resulting in the shedding of the active material and the rapid decrease in cycle life. Shortcomings, and the carbon material located in the shell can also limit the expansion of the negative electrode material to a certain extent. In addition, silicon dioxide can also firmly connect titanium dioxide and carbon materials through chemical bonds, thereby making the structure of the entire negative electrode material stable; On the one hand, the core layer is covered by the shell layer, so that the titanium dioxide in the core layer is not easy to agglomerate, thereby increasing the diffusion rate of lithium ions in titanium dioxide; on the other hand, the carbon material in the shell layer can improve the ionic conductivity and Electronic conductivity, the lithium-ion battery containing the composite material has excellent cycle performance and excellent rate performance.

Another object of the present invention is to provide a kind of preparation method of negative electrode composite material for lithium ion battery, comprising the following steps:

The first step is to weigh the silicate, titanate and surfactant respectively according to the molar ratio, add the silicate, titanate and surfactant to the solvent, mix and stir evenly, add ammonia water dropwise during the stirring process, adjust When the pH value reaches 6.5-9.5, a precipitate is formed, and the intermediate product is obtained after centrifugation;

In the second step, the intermediate product obtained in the first step is dried, and then calcined at a temperature of 500° C. to 1200° C. under an inert atmosphere to obtain a product.

Compared with the prior art, the present invention uses silicate and titanate as precursors, and adds a surfactant, so that the silicate and titanate are coated in the uniform and fine micelles formed by the surfactant , and then by adding ammonia water dropwise, the precursor is precipitated, and then through separation, calcination, etc., a composite material with a core layer containing titanium dioxide and silicon dioxide and a shell layer containing carbon materials can be obtained, and the obtained composite material particles Small, uniform particle size and composition distribution, carbon materials can also be distributed into the pores of titanium dioxide and silicon dioxide, thereby improving the ionic conductivity and electronic conductivity of the negative electrode material. Moreover, the method has simple process, mild reaction conditions, low cost and is convenient for large-scale production.

As an improvement of the preparation method of the negative electrode composite material for lithium ion batteries of the present invention, the silicate is at least one of ethyl orthosilicate, methyl orthosilicate, propyl orthosilicate and tetrabutyl A sort of.

As an improvement to the preparation method of the negative electrode composite material for lithium ion batteries of the present invention, the titanate is at least one of tetrabutyl titanate, tetraisopropyl titanate and ethyl titanate.

As an improvement of the preparation method of the negative electrode composite material for lithium ion batteries of the present invention, the surfactant is sodium lauryl sulfate, stearic acid, sodium dodecylbenzenesulfonate and lignosulfonate At least one of these surfactants can form uniform micelles and can form carbon materials after calcination.

As an improvement to the preparation method of the negative electrode composite material for lithium ion batteries of the present invention, the solvent is at least one of ethanol, methanol, acetone and ethylene glycol.

As an improvement to the preparation method of the negative electrode composite material for lithium ion batteries of the present invention, the stirring speed in the first step is 50-500 rpm, and the stirring duration is 0.1h-3h.

As an improvement of the preparation method of the negative electrode composite material for lithium ion batteries of the present invention, the drying temperature in the second step is 60°C to 90°C, the duration of drying is 1h to 10h, and the calcination is carried out in a tube furnace. The inert gas is nitrogen or argon. During calcination, the tube furnace first raises the temperature to 500°C-1200°C at a rate of 5°C/min-20°C/min and then keeps it warm for 1h-5h.

Description of drawings

The present invention and its beneficial technical effects will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

FIG. 1 is an SEM image of the negative electrode composite material provided in Example 1 of the present invention.

Fig. 2 is a graph of the cycle life of the battery numbered S1 in the present invention.

Fig. 3 is a charge-discharge curve diagram of the 40th cycle of the battery numbered S1 in the present invention.

detailed description

Example 1

A negative electrode composite material for a lithium ion battery provided in this embodiment, the composite material has a core-shell structure comprising a core layer and a shell layer;

The core layer is a mixture of titanium dioxide and silicon dioxide (a solid solution of the two) and titanium dioxide and silicon dioxide, and the mass ratio of titanium dioxide and silicon dioxide is 1:1.5, wherein titanium dioxide is anatase type titanium dioxide. Anatase titanium dioxide belongs to the tetragonal crystal system, based on TiO ₆ octahedron, and is formed by sharing four sides and common vertices. It has two-way pore channels, along the a-axis and b-axis respectively, and has a high lithium intercalation capacity. When lithium ions are intercalated, it first forms a lithium-poor phase Li _0.01 TiO ₂ with a tetragonal structure and a lithium-rich phase Li _0.6 TiO ₂ with an orthorhombic structure, so that lithium ions can flow between the two phases to achieve a dynamic balance. The position remains constant, and its theoretical lithium intercalation specific capacity is 335mAh/ _g , but the actual reversible capacity is usually only about half of the theoretical capacity. role, hindering further intercalation of Li ⁺ , reducing its size can improve its lithium deintercalation capacity, therefore, the size of titanium dioxide in this embodiment is smaller.

The shell layer is a carbon material, specifically hard carbon, and the mass percentage of the shell layer in the composite material is 10%. The particle diameter of the core layer is 100 nm, the thickness of the shell layer is 0.1 μm, and the carbon material is also embedded in the micropores of titania and silica.

The preparation method of negative electrode composite material for lithium ion battery comprises the following steps:

The first step is to weigh ethyl orthosilicate, tetrabutyl titanate and sodium lauryl sulfate respectively according to the molar ratio, wherein the molar ratio of ethyl orthosilicate and tetrabutyl titanate is 2:1, Add ethyl orthosilicate, tetrabutyl titanate and sodium lauryl sulfate into ethanol, mix and stir evenly, the stirring speed is 100 rpm, and the stirring duration is 2 hours. During the stirring process, ammonia water is added dropwise to adjust When the pH value reaches 7.5, a precipitate is formed, and an intermediate product is obtained after centrifugation;

In the second step, the intermediate product obtained in the first step is dried, the drying temperature is 70°C, and the duration of drying is 3h, and then the dried product is placed in a tube furnace at a rate of 10°C/min. The heating rate was raised to 1000° C., and then kept for 3 hours, followed by calcination to obtain the product.

Carry out SEM test to the negative electrode composite material prepared according to the method of this embodiment, the obtained results are shown in Figure 1, as can be seen from Figure 1: the shape and size of the negative electrode composite material of this embodiment are relatively uniform, and the negative electrode composite material The particle size is very small.

Example 2

A negative electrode composite material for a lithium ion battery provided in this embodiment, the composite material has a core-shell structure comprising a core layer and a shell layer;

The core layer is a mixture of titanium dioxide and silicon dioxide (a solid solution of the two) and titanium dioxide and silicon dioxide, and the mass ratio of titanium dioxide and silicon dioxide is 5:1, wherein titanium dioxide is rutile titanium dioxide . Rutile-type titanium dioxide belongs to the tetragonal crystal system, with TiO ₆ coordination octahedrons arranged in chains along the c-axis, sharing one edge with the upper and lower TiO ₆ coordination octahedrons, and the chains are connected by the coordination octahedrons sharing vertices. Due to the large amount of lattice distortion on the ab plane of the rutile-type titanium dioxide lattice, there is anisotropy in the Li ⁺ migration channel parallel to the c-axis, and the position of Li ⁺ embedded in the rutile lattice is far away from the a,b direction of the main channel, so that The diffusion process is slow, and the lithium intercalation performance is not good. Reducing its size can improve its lithium deintercalation capacity. Therefore, the size of titanium dioxide in this embodiment is small.

The shell layer is a carbon material, specifically soft carbon, and the mass percentage of the shell layer in the composite material is 15%. The particle diameter of the core layer is 500 nm, the thickness of the shell layer is 0.5 μm, and the carbon material is also embedded in the micropores of titania and silica.

The preparation method of negative electrode composite material for lithium ion battery comprises the following steps:

In the first step, take methyl orthosilicate, tetraisopropyl titanate and stearic acid respectively according to molar ratio, wherein, the molar ratio of methyl orthosilicate and tetraisopropyl titanate is 4:15, and Add methyl orthosilicate, tetraisopropyl titanate and stearic acid into methanol and mix well. The stirring speed is 300 rpm, and the stirring time is 1 hour. During the stirring process, ammonia water is added dropwise to adjust the pH value to 8.5, a precipitate is formed, and an intermediate product is obtained after centrifugation;

In the second step, the intermediate product obtained in the first step is dried, the drying temperature is 80°C, and the duration of drying is 5h, and then the dried product is placed in a tube furnace at a rate of 15°C/min. The heating rate was raised to 900° C. and then kept for 4 hours, followed by calcination to obtain the product.

Example 3

A negative electrode composite material for a lithium ion battery provided in this embodiment, the composite material has a core-shell structure comprising a core layer and a shell layer;

The core layer is a mixture of titanium dioxide and silicon dioxide, and the mass ratio of titanium dioxide and silicon dioxide is 0.5:1, wherein the titanium dioxide is anatase titanium dioxide.

The shell layer is made of carbon material, specifically graphite, and the mass percentage of the shell layer in the composite material is 18%. The particle diameter of the core layer is 1500 nm, the thickness of the shell layer is 1 μm, and the carbon material is also embedded in the micropores of titania and silica.

The preparation method of negative electrode composite material for lithium ion battery comprises the following steps:

The first step is to weigh propyl orthosilicate, ethyl titanate and sodium dodecylbenzenesulfonate respectively according to the molar ratio, wherein the molar ratio of propyl orthosilicate and ethyl titanate is 8:3, Add propyl orthosilicate, ethyl titanate and sodium dodecylbenzenesulfonate to acetone and mix well, the stirring speed is 400 rpm, the stirring duration is 0.5h, and ammonia water is added dropwise during the stirring process , adjust the pH value to 8.0, form a precipitate, and obtain an intermediate product after centrifugation;

In the second step, the intermediate product obtained in the first step is dried, the drying temperature is 75°C, and the duration of drying is 7h, and then the dried product is placed in a tube furnace at a rate of 8°C/min. The heating rate was raised to 600° C. and then kept for 5 hours, followed by calcination to obtain the product.

Example 4

A negative electrode composite material for a lithium ion battery provided in this embodiment, the composite material has a core-shell structure comprising a core layer and a shell layer;

The core layer is a composite formed of titanium dioxide and silicon dioxide (a solid solution of the two), and the mass ratio of titanium dioxide and silicon dioxide is 0.8:1, wherein the titanium dioxide is brookite-type titanium dioxide. Brookite-type titanium dioxide belongs to the orthorhombic crystal system, which is composed of TiO ₆ octahedron sharing edges and sharing vertices. Li ⁺ is embedded in its lattice along the c-axis {001} direction with less resistance, and the diffusion process is one-dimensional. The radius of the pore channel is about 5.8nm, the pore spacing in the a and b directions is small, the diffusion process is limited, and the lithium deintercalation capacity is small, but the lithium deintercalation capacity can be improved by reducing the size. Therefore, this embodiment Titanium dioxide is smaller in size. Moreover, the structure of brookite-type titanium dioxide basically does not change significantly during the Li ⁺ intercalation process, which can ensure its structural stability during multiple charge and discharge.

The shell layer is a carbon material, specifically graphite, and the shell layer accounts for 8% by mass of the composite material. The particle diameter of the core layer is 1000nm, the thickness of the shell layer is 300nm, and the carbon material is also embedded in the micropores of titanium dioxide and silicon dioxide.

The preparation method of negative electrode composite material for lithium ion battery comprises the following steps:

In the first step, tetrabutyl silicate, ethyl titanate and lignosulfonate were weighed respectively according to the molar ratio, wherein the molar ratio of tetrabutyl silicate and ethyl titanate was 5:3, and the silicic acid Add tetrabutyl ester, ethyl titanate and lignin sulfonate into ethylene glycol and mix well. The stirring speed is 80 rpm, and the stirring duration is 2.8 hours. During the stirring process, add ammonia water dropwise to adjust the pH value. To 6.5, a precipitate is formed, and an intermediate product is obtained after centrifugation;

In the second step, the intermediate product obtained in the first step is dried, the drying temperature is 90°C, and the duration of drying is 1h, and then the dried product is placed in a tube furnace at a rate of 18°C/min. The heating rate was raised to 1200° C., and then kept for 1.5 hours for calcination to obtain the product.

Example 5

A negative electrode composite material for a lithium ion battery provided in this embodiment, the composite material has a core-shell structure comprising a core layer and a shell layer;

The core layer is a mixture of a composite formed of titanium dioxide and silicon dioxide (a solid solution of the two) and titanium dioxide and silicon dioxide, and the mass ratio of titanium dioxide and silicon dioxide is 0.3:1, wherein titanium dioxide is rutile titanium dioxide .

The shell layer is made of carbon material, specifically hard carbon, and the mass percentage of the shell layer in the composite material is 6%. The particle diameter of the core layer is 150nm, the thickness of the shell layer is 700nm, and the carbon material is also embedded in the micropores of titanium dioxide and silicon dioxide.

The preparation method of negative electrode composite material for lithium ion battery comprises the following steps:

The first step is to weigh silicate (a mixture of tetrabutyl silicate and methyl orthosilicate, the mass ratio of the two is 1:1), titanate (tetrabutyl titanate and titanic acid) according to the molar ratio. A mixture of ethyl ester, the mass ratio of the two is 2:1) and a surfactant (a mixture of sodium lauryl sulfate and lignosulfonate, the mass ratio of the two is 3:1), silicate and The mass ratio of titanate is 40:9, tetrabutyl silicate, methyl orthosilicate, ethyl titanate, tetrabutyl titanate, sodium lauryl sulfate and lignosulfonate are added to ethanol Mix and stir evenly, the stirring speed is 350 rpm, and the stirring duration is 1.2h. During the stirring process, add ammonia water dropwise, adjust the pH value to 9.0, form a precipitate, and obtain an intermediate product after centrifugation;

In the second step, the intermediate product obtained in the first step is dried, the drying temperature is 70°C, and the duration of drying is 4h, and then the dried product is placed in a tube furnace at a rate of 7°C/min. The heating rate was raised to 800° C. and then kept for 5 hours, followed by calcination to obtain the product.

The negative electrode composite material that embodiment 1 to 5 provides is tested as follows:

First, mix the negative electrode composite materials provided in Examples 1 to 5 with the conductive agent acetylene black and the binder PVDF according to the mass ratio of 8:1:1, and use NMP to prepare the mixture into a slurry, and evenly coat it on the copper foil Put it in an oven to dry at 90°C for 2 hours, take it out and punch it into a pole piece, dry it in vacuum at 120°C for 12 hours, roll it, and dry it in vacuum at 85°C for 12 hours to prepare a pole piece for a laboratory battery. The lithium sheet is used as the counter electrode, the solute in the electrolyte is 1mol/L LiPF ₆ , the solvent is a mixed solvent of EC and DMC with a volume ratio of 1:1, and the diaphragm is a Celgard2400 membrane, which is assembled into a CR2025 in a glove box filled with an argon atmosphere. The button batteries are numbered S1-S5 respectively, the charge and discharge cut-off voltage is 0.01-1.5V, and the charge density is 0.1A/g. The cycle performance of the batteries numbered S1-S5 is tested, and the first discharge specific capacity and cycle performance are recorded. Discharge specific capacity after 40 cycles, and calculate the capacity retention rate after 40 cycles, the results are shown in Table 1.

As a comparison, pure silicon dioxide is used as the negative electrode material, and the rest is the same as above to make a CR2025 button battery, which is numbered D1, with a charge-discharge cut-off voltage of 0.01-1.5V, a charge density of 0.1A/g, and a test number of S1- For the cycle performance of the S5 battery, the first discharge specific capacity and the discharge specific capacity after 40 cycles were recorded, and the capacity retention rate after 40 cycles was calculated. The results are shown in Table 1.

Table 1: Cycle performance test results of batteries numbered S1-S5 and D1.

It can be seen that the battery comprising the negative electrode composite material of the present invention has excellent cycle performance.

Wherein, the cycle life curve of the battery numbered S1 is also shown in FIG. 2 , and the charge-discharge curve at the 40th cycle is also shown in FIG. 3 .

In order to test the rate performance of the battery, the batteries numbered S1-S5 and D1 were cycle tested at the charging density of 0.5A/g, 1.0A/g and 2.0A/g, and the capacity retention rate after 40 cycles was calculated , and the results are shown in Table 2.

Table 2: Rate performance test results of batteries numbered S1-S5 and D1.

It can be seen from Table 2 that the battery comprising the negative electrode composite material of the present invention has excellent rate performance.

According to the disclosure and teaching of the above specification, those skilled in the art to which the present invention pertains can also make changes and modifications to the above embodiment. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims (9)

1. a kind of negative electrode for lithium ion battery composite comprises stratum nucleare and shell it is characterised in that described composite has Nucleocapsid structure；

Described stratum nucleare is the mixture of titanium dioxide and silicon dioxide；Or, described stratum nucleare is titanium dioxide and silicon dioxide shape The complex becoming；Or, described stratum nucleare is complex, titanium dioxide and the silicon dioxide being formed by titanium dioxide and silicon dioxide The mixture of composition；And the mass ratio of described titanium dioxide and described silicon dioxide is (0.1～10): 1；

Described shell be material with carbon element, and described shell account for described composite mass percent be 5%～20%；

Its preparation method comprises the following steps:

The first step, in molar ratio example weigh esters of silicon acis, titanate esters and surfactant respectively, by esters of silicon acis, titanate esters and surface Activating agent adds mixing and stirring in solvent, Deca ammonia in whipping process, adjusts ph value to 6.5～9.5, is formed and sink Form sediment, after centrifugation, obtain intermediate product；

Second step, the intermediate product that the first step is obtained is dried, and is then entered with 500 DEG C～1200 DEG C of temperature under an inert atmosphere Row calcining, obtains product.

2. negative electrode for lithium ion battery composite according to claim 1 it is characterised in that: described titanium dioxide be sharp Titanium ore type titanium dioxide, rutile titanium dioxide or brookite type titanium dioxide.

3. negative electrode for lithium ion battery composite according to claim 1 it is characterised in that: the particle diameter of described stratum nucleare is 50nm～2 μm, the thickness of described shell is 50nm～1 μm.

4. negative electrode for lithium ion battery composite according to claim 1 it is characterised in that: described titanium dioxide and institute It is embedded with described material with carbon element, described material with carbon element is at least one in hard carbon, soft carbon and graphite in the micropore stating silicon dioxide.

5. negative electrode for lithium ion battery composite according to claim 1 it is characterised in that: described esters of silicon acis be positive silicon At least one in acetoacetic ester, methyl silicate, positive silicic acid propyl ester and silicic acid four butyl ester.

6. negative electrode for lithium ion battery composite according to claim 1 it is characterised in that: described titanate esters be metatitanic acid At least one in four butyl esters, tetraisopropyl titanate and tetraethyl titanate.

7. negative electrode for lithium ion battery composite according to claim 1 it is characterised in that: described surfactant is At least one in sodium lauryl sulphate, stearic acid, dodecylbenzene sodium sulfonate and lignosulfonates.

8. negative electrode for lithium ion battery composite according to claim 1 it is characterised in that: described solvent be ethanol, At least one in methanol, acetone and ethylene glycol.

9. negative electrode for lithium ion battery composite according to claim 5 it is characterised in that: stirring in first step speed Spend for 50～500 turns/min, stirring duration is 0.1h～3h, in second step, drying temperature is 60 DEG C～90 DEG C, dry Persistent period be 1h～10h, calcining is carried out in tube furnace, and noble gases are nitrogen or argon, during calcining, tube furnace first with The programming rate of 5 DEG C/min～20 DEG C/min is incubated 1h～5h after being warming up to 500 DEG C～1200 DEG C.