Carbon matrix composite material, preparation method therefor and lithium ion battery comprising same

Abstract

A carbon matrix composite material, a preparation method therefor and a battery comprising the same. The carbon matrix composite material comprises micron-sized soft carbon, micron-sized hard carbon, a nano-active material, a first carbon coating layer and a second carbon coating layer, wherein the first carbon coating layer is coated on a surface of the nano-active material to form composite particles; the composite particles are dispersed on the surfaces of the soft carbon and the hard carbon, and in the second carbon coating layer; and the second carbon coating layer coats soft carbon, the hard carbon and the composite particles.

Claims

1. A carbon-based composite material, comprising a micron-sized soft carbon, a micron-sized hard carbon, a nano-active substance, a first carbon coating layer and a second carbon coating layer; the first carbon coating layer is coated on the surface of the nano-active substance to form composite particles; the composite particles are dispersed on the surfaces of the soft carbon and the hard carbon and dispersed into the second carbon coating layer; the second carbon coating layer is disposed to coat the soft carbon, the hard carbon and the composite particles.

2. The carbon-based composite material according to claim 1, wherein the ratio of the median particle diameter of the soft carbon to that of the hard carbon is 1:(1-3).

3. The carbon-based composite material according to claim 1 wherein the carbon-based composite material contains the nano-active substance in a proportion of 1-60 wt %, the first carbon coating layer in a proportion of 0.2-15 wt %, the soft carbon in a proportion of 15-60 wt %, the hard carbon in a proportion of 15-60 wt %, and the second carbon coating layer in a proportion of 5-50 wt %.

4. The carbon-based composite material according to claim 3, wherein the carbon-based composite material contains the nano-active substance in a proportion of 10-50 wt %, the first carbon coating layer in a proportion of 0.5-13 wt %, the soft carbon in a proportion of 20-50 wt %, the hard carbon in a proportion of 20-50 wt %, and the second carbon coating layer in a proportion of 10-40 wt %.

5. The carbon-based composite material according to claim 1, wherein the nano-active material comprises a material that is electrochemically active to lithium.

6. The carbon-based composite material according to claim 1, wherein the nano-active substance comprises any one selected from the group consisting of a silicon elementary substance, a tin elementary substance, an antimony elementary substance, a germanium elementary substance, an aluminum elementary substance, a magnesium elementary substance, a zinc elementary substance, a gallium elementary substance, a cadmium elementary substance, a titanium oxide, a silicon oxide, a tin oxide, a cobalt oxide, an iron oxide, a copper oxide, a manganese oxide, a nickel oxide, a tin-antimony alloy, an indium-antimony alloy, a silver-antimony alloy, an aluminum-antimony alloy, a silver-tin alloy, a silicon-iron alloy, a silicon-magnesium compound, and a silicon-iron compound, or a combination of at least two selected therefrom.

7. The carbon-based composite material according to claim 1, wherein the soft carbon comprises an amorphous carbon material which is configured to be graphitized after heat treatment at 800-3200° C., the amorphous carbon material comprising any one selected from the group consisting of coke, carbon fibers, and mesocarbon microbeads, or a combination of at least two selected therefrom.

8. The carbon-based composite material according to claim 1, wherein the hard carbon comprises an amorphous carbon material which is configured to be graphitized after heat treatment at 800-3200° C., the amorphous carbon material comprising any one selected from the group consisting of a resin carbon, an organic polymer pyrolytic carbon, a plant hard carbon, and an asphalt hard carbon, or a combination of at least two selected therefrom.

9. The carbon-based composite material according to claim 1, wherein the median particle diameter of the carbon-based composite material is 1-45 μm.

10. A lithium ion battery, wherein, the anode active material of the lithium ion battery comprises the carbon-based composite material of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic structural view of the carbon-based composite material in Example 1 of the present application;

(2) FIG. 2 is a scanning electron microscope image of the carbon-based composite anode material in Example 1 of the present application;

(3) FIG. 3 is an XRD pattern of the carbon-based composite anode material in Example 1 of the present application;

(4) FIG. 4 is a first charge-discharge curve of a battery comprising the carbon-based composite anode material in Example 1 of the present application;

(5) FIG. 5 is a cycle performance curve of a battery comprising the carbon-based composite anode material in Example 1 of the present application.

DETAILED DESCRIPTION

(6) The technical solution of the present application is further illustrated below by the specific embodiments in combination with the appended drawings.

EXAMPLE 1

(7) (1) Si with a particle size of 30-120 nm was placed in a rotary furnace, the rotary speed was adjusted to be 1 r/min, nitrogen gas was introduced, the temperature was raised to 800° C. at a temperature raising rate of 0.5° C./min, acetylene gas was introduced at a flow rate of 1.5 L/min, the temperature was maintained for 1 h, followed by natural cooling to room temperature, thus a carbon-coated nano-active substance, namely the composite particles consisting of the nano-active substance and a first carbon coating layer, was obtained;

(8) (2) coke with a median particle diameter of 3-5 μm, plant hard carbon with a median particle diameter of 5-7 μm and the carbon-coated nano-active substance were placed in a fusion machine in a mass ratio of 40:40:20, the rotating speed was adjusted to be 2500 r/min, the cutter gap width was set to be 0.1 cm, fusion was conducted for 1 h, thus a first precursor was obtained;

(9) (3) the first precursor and asphalt powder with a particle size of 0.5-10 μm were placed in a VC high-efficiency mixer in a mass ratio of 70:30 where the rotating speed was adjusted to be 1500 r/min, and mixed for 0.5 h, thus a second precursor was obtained;

(10) (4) the second precursor was VC hot mixed at 300° C. for 1 h, thus a third precursor was obtained;

(11) (5) the third precursor was placed in a box furnace, argon gas was introduced, the temperature was raised to 900° C. at a temperature raising rate of 1.5° C./min and maintained for 3 h, followed by natural cooling to room temperature, then it was crushed, screened and demagnetized, thus a carbon-based composite material with a particle size of 1-45 μm was obtained, which is a high capacity rate type carbon-based composite anode material and comprises the nano-active substance in a proportion of 16 wt %, the first carbon coating layer in a proportion of 2 wt %, soft carbon in a proportion of 30 wt %, hard carbon in a proportion of 30 wt % and the second carbon coating layer in a proportion of 22 wt %.

(12) FIG. 1 is a schematic structural view of the carbon-based composite material in this example. As can be seen from FIG. 1, in this example, the carbon-based composite material comprises a soft carbon (coke), a hard carbon (plant hard carbon), a nano-active substance (Si), a first carbon coating layer and a second carbon coating layer; the first carbon coating layer is coated on the surface of the nano-active substance to form composite particles; the composite particles are dispersed on the surfaces of the soft carbon and the hard carbon and in the second carbon coating layer; and the second carbon coating layer is the outermost layer structure of the carbon-based composite material and is disposed to coat the soft carbon, the hard carbon and the composite particles.

(13) FIG. 2 is a scanning electron microscope image of the carbon-based composite anode material in this example, from which it can be seen that the composite anode material is formed by irregular particles having a median particle diameter of around 12 μm.

(14) FIG. 3 is an XRD pattern of the carbon-based composite anode material in this example, and characteristic peaks of soft carbon, hard carbon, and nano-silicon can be seen.

(15) FIG. 4 is a first charge-discharge curve of a battery comprising the carbon-based composite anode material in this example, from which it can be seen that the first reversible capacity is 818.5 mAh/g and the first coulombic efficiency is 88.7%.

(16) FIG. 5 is a cycle performance curve of a battery comprising the carbon-based composite anode material in this example, from which it can be seen that the capacity retention is 91.7% after 300 cycles.

EXAMPLE 2

(17) (1) a silicon-iron alloy with a particle size of 120-180 nm was placed in a rotary furnace, the rotary speed was adjusted to be 1.5 r/min, nitrogen gas was introduced, the temperature was raised to 1000° C. at a temperature raising rate of 7° C./min, methane gas was introduced at a flow rate of 2.5 L/min, the temperature was maintained for 0.5 h, followed by natural cooling to room temperature, thus a carbon-coated nano-active substance, namely the composite particles consisting of the nano-active substance and a first carbon coating layer, was obtained;

(18) (2) mesocarbon microbeads with a median particle diameter of 4-7 μm, resin carbon with a median particle diameter of 6-9 μm, the carbon-coated nano-active substance and sodium dodecyl sulfate were dispersed into propyl alcohol in a mass ratio of 43:30:25:2, and the mixture was spray dried, thus a first precursor was obtained;

(19) (3) the first precursor and asphalt powder with a particle size of 1-7 μm were placed in a VC high-efficiency mixer in a mass ratio of 65:35 where the rotating speed was adjusted to be 3000 r/min, and mixed for 1 h, thus a second precursor was obtained;

(20) (4) the second precursor was treated by kneading molding at 350° C. for 0.5 h, thus a third precursor was obtained;

(21) (5) the third precursor was placed in a pipe furnace, nitrogen gas was introduced, the temperature was raised to 750° C. at a temperature raising rate of 3° C./min and maintained for 5 h, followed by natural cooling to room temperature, then it was crushed, screened and demagnetized, thus a carbon-based composite material with a particle size of 1-45 μm was obtained, which is a high capacity rate type carbon-based composite anode material and comprises the nano-active substance in a proportion of 20 wt %, the first carbon coating layer in a proportion of 1.5 wt %, soft carbon in a proportion of 32 wt %, hard carbon in a proportion of 22.5 wt % and the second carbon coating layer in a proportion of 24 wt %. In this example, the carbon-based composite material comprises a soft carbon (mesocarbon microbeads), a hard carbon (resin carbon), a nano-active substance (silicon-iron alloy), a first carbon coating layer and a second carbon coating layer; the first carbon coating layer is coated on the surface of the nano-active substance to form composite particles; the composite particles are dispersed on the surfaces of the soft carbon and the hard carbon and in the second carbon coating layer; and the second carbon coating layer is the outermost layer structure of the carbon-based composite material and is disposed to coat the soft carbon, the hard carbon and the composite particles.

EXAMPLE 3

(22) (1) Si with a particle size of 20-50 nm was placed in a rotary furnace, the rotary speed was adjusted to be 3 r/min, nitrogen gas was introduced, the temperature was raised to 900° C. at a temperature raising rate of 3° C./min, acetone gas was introduced at a flow rate of 7 L/min, the temperature was maintained for 0.2 h, followed by natural cooling to room temperature, thus a carbon-coated nano-active substance, namely the composite particles consisting of the nano-active substance and a first carbon coating layer, was obtained;

(23) (2) carbon fibers with a median particle diameter of 5-8 μm, asphalt hard carbon with a median particle diameter of 5-8 μm, the carbon-coated nano-active substance and a fatty acid polyethylene glycol ester were dispersed into ethyl alcohol in a mass ratio of 45:20:30:5, and the mixture was spray dried, thus a first precursor was obtained;

(24) (3) the first precursor and glucose were dispersed in ethyl alcohol in a mass ratio of 65:35, the mixture was spray dried, thus a second precursor was obtained;

(25) (4) the second precursor was treated by kneading molding at 200° C. for 2 h, thus a third precursor was obtained;

(26) (5) the third precursor was placed in a roller kiln, nitrogen gas was introduced, the temperature was raised to 980° C. at a temperature raising rate of 4° C./min and maintained for 2 h, followed by natural cooling to room temperature, then it was crushed, screened and demagnetized, thus a carbon-based composite material with a particle size of 1-45 μm was obtained, which is a high capacity rate type carbon-based composite anode material and comprises the nano-active substance in a proportion of 28 wt %, the first carbon coating layer in a proportion of 4 wt %, soft carbon in a proportion of 36 wt %, hard carbon in a proportion of 16 wt % and the second carbon coating layer in a proportion of 16 wt %. In this example, the carbon-based composite material comprises a soft carbon (carbon fibers), a hard carbon (asphalt hard carbon), a nano-active substance (Si), a first carbon coating layer and a second carbon coating layer; the first carbon coating layer is coated on the surface of the nano-active substance to form composite particles; the composite particles are dispersed on the surfaces of the soft carbon and the hard carbon and in the second carbon coating layer; and the second carbon coating layer is the outermost layer structure of the carbon-based composite material and is disposed to coat the soft carbon, the hard carbon and the composite particles.

EXAMPLE 4

(27) (1) SnO with a particle size of 150-180 nm was placed in a rotary furnace, the rotary speed was adjusted to be 5 r/min, nitrogen gas was introduced, the temperature was raised to 850° C. at a temperature raising rate of 1° C./min, acetylene gas was introduced at a flow rate of 0.5 L/min, the temperature was maintained for 3 h, followed by natural cooling to room temperature, thus a carbon-coated nano-active substance, namely the composite particles consisting of the nano-active substance and a first carbon coating layer, was obtained;

(28) (2) coke with a median particle diameter of 3-5 μm, organic polymer pyrolytic carbon with a median particle diameter of 9-13 μm and the carbon-coated nano-active substance were placed in a fusion machine in a mass ratio of 25:40:35, the rotating speed was adjusted to be 2000 r/min, the cutter gap width was set to be 0.5 cm, fusion was conducted for 1.5 h, thus a first precursor was obtained;

(29) (3) the first precursor and citric acid were dispersed in ethyl alcohol in a mass ratio of 60:40, the mixture was spray dried, thus a second precursor was obtained;

(30) (4) the second precursor was VC hot mixed at 160° C. for 0.5 h, thus a third precursor was obtained;

(31) (5) the third precursor was placed in a rotary furnace, argon gas was introduced, the temperature was raised to 650° C. at a temperature raising rate of 7° C./min and maintained for 1 h, followed by natural cooling to room temperature, then it was crushed, screened and demagnetized, thus a carbon-based composite material with a particle size of 1-45 μm was obtained, which is a high capacity rate type carbon-based composite anode material and comprises the nano-active substance in a proportion of 26.5 wt %, the first carbon coating layer in a proportion of 1.2 wt %, soft carbon in a proportion of 20 wt %, hard carbon in a proportion of 32 wt % and the second carbon coating layer in a proportion of 20.3 wt %. In this example, the carbon-based composite material comprises a soft carbon (coke), a hard carbon (organic polymer pyrolytic carbon), a nano-active substance (SnO), a first carbon coating layer and a second carbon coating layer; the first carbon coating layer is coated on the surface of the nano-active substance to form composite particles; the composite particles are dispersed on the surfaces of the soft carbon and the hard carbon and in the second carbon coating layer; and the second carbon coating layer is the outermost layer structure of the carbon-based composite material and is disposed to coat the soft carbon, the hard carbon and the composite particles.

EXAMPLE 5

(32) (1) SiO nano-particles with a particle size of 100-130 nm was placed in a rotary furnace, the rotary speed was adjusted to be 1 r/min, argon gas was introduced, the temperature was raised to 1050° C. at a temperature raising rate of 2° C./min, methane gas was introduced at a flow rate of 1 L/min, the temperature was maintained for 1 h, followed by natural cooling to room temperature, thus a carbon-coated nano-active substance, namely the composite particles consisting of the nano-active substance and a first carbon coating layer, was obtained;

(33) (2) coke with a median particle diameter of 7-9 μm, resin carbon with a median particle diameter of 10-13 μm and a carbon-coated nano-active substance were dispersed into propyl alcohol in a mass ratio of 45:30:25, and the mixture was dried by rotary evaporation, thus a first precursor was obtained;

(34) (3) the first precursor and sucrose were placed in a VC high-efficiency mixer in a mass ratio of 60:40 where the rotating speed was adjusted to be 2000 r/min, and mixed for 0.5 h, thus a second precursor was obtained;

(35) (4) the second precursor was VC hot mixed at 200° C. for 1.5 h, thus a third precursor was obtained;

(36) (5) the third precursor was placed in a roller kiln, nitrogen gas was introduced, the temperature was raised to 1050° C. at a temperature raising rate of 5° C./min and maintained for 2 h, followed by natural cooling to room temperature, then it was crushed, screened and demagnetized, thus a carbon-based composite material with a particle size of 1-45 μm was obtained, which carbon-based composite material is a high capacity rate type carbon-based composite anode material and comprises the nano-active substance in a proportion of 18 wt %, the first carbon coating layer in a proportion of 1.6 wt %, soft carbon in a proportion of 35 wt %, hard carbon in a proportion of 23 wt % and the second carbon coating layer in a proportion of 22.4 wt %. In this example, the carbon-based composite material comprises a soft carbon (coke), a hard carbon (resin carbon), a nano-active substance (SiO), a first carbon coating layer and a second carbon coating layer; the first carbon coating layer is coated on the surface of the nano-active substance to form composite particles; the composite particles are dispersed on the surfaces of the soft carbon and the hard carbon and in the second carbon coating layer; and the second carbon coating layer is the outermost layer structure of the carbon-based composite material and is disposed to coat the soft carbon, the hard carbon and the composite particles.

Comparison Example 1

(37) An activated carbon composite anode material was prepared in substantially the same manner as in Example 1, except that: the nano-active substance was not subjected to carbon coating, no hard carbon was added, coating modification was not performed, and VC heating or kneading molding treatment was not performed; and a battery was manufactured in the same manner as in Example 1.

Comparison Example 2

(38) A composite anode material was prepared in substantially the same manner as in Example 1, except that: the nano-active substance was not subjected to carbon coating, a soluble carbon-containing organic binder was used for replacing carbonized hard carbon, and VC heating or kneading molding treatment was not performed; and a battery was manufactured in the same manner as in Example 1.

Comparison Example 3

(39) An activated carbon composite anode material was prepared in substantially the same manner as in Example 1, except that: coke with a median particle diameter of 10-14 μm and plant hard carbon with a median particle diameter of 5-7 μm were used; and a battery was manufactured in the same manner as in Example 1.

Comparison Example 4

(40) An activated carbon composite anode material was prepared in substantially the same manner as in Example 1, except that: coke with a median particle diameter of 3-5 μm and plant hard carbon with a median particle diameter of 11-17 μm were used; and a battery was manufactured in the same manner as in Example 1.

(41) The anode materials of Examples 1-5 and Comparison Examples 1-4 were tested by the following methods:

(42) {circle around (1)} For the particle diameter described in the present application, a Malvern laser particle size analyzer MS 2000 was adopted to test the particle diameter range of the material and the average particle diameter of the raw material particles.

(43) {circle around (2)} An X-ray diffractometer X′ Pert Pro, PANalytical was adopted to test the structure of the material.

(44) {circle around (3)} A Hitachi S4800 scanning electron microscope was adopted to observe the surface topography, the particle size and the like of the sample.

(45) {circle around (4)} The first charge-discharge performance was tested by adopting the following method:

(46) the anode materials from these examples and comparison examples, a conductive agent and a binder in a mass ratio of 95:2:3 were dissolved in a solvent for blending, the resulting mixture slurry was coated on a copper foil current collector, and vacuum dried to obtain an anode plate; then the CR 2016 button cell was assembled from 1 mol/L LiPF6/EC+DMC+EMC (v/v=1:1:1) electrolyte, SK (12 μm) separator, and a housing by using a conventional process.

(47) The charge-discharge test of the button cell was carried out on a LAND cell test system from Wuhan Kingnuo Electronics Co., Ltd. under the condition of normal temperature and of constant current charging and discharging at a rate of 0.1 C, with the charge-discharge voltage being limited to be 0.005-1.5 V.

(48) {circle around (5)} the rate and the cycle performance were tested by the following methods:

(49) the anode materials from these examples and comparison examples, a conductive agent and a binder in a mass ratio of 95:2:3 were dissolved in a solvent for blending, the resulting mixture slurry was coated on a copper foil current collector, and vacuum dried to obtain an anode plate; then the 18650 cylindrical single cell was assembled from a ternary cathode plate prepared by a conventional mature process, 1 mol/L LiPF.sub.6/EC+DMC+EMC (v/v=1:1:1) electrolyte, SK (12 μm) separator, and a housing by using a conventional production process.

(50) The charge-discharge test of the cylindrical cell was carried out on a LAND cell test system of Wuhan Kingnuo Electronics Co., Ltd. under the condition of normal temperature and of constant current charging and discharging at a rate of 1 C, 10 C and 20 C, with the charge-discharge voltage being limited to be 2.75-4.2 V.

(51) The results of electrochemical tests of the anode materials prepared in Examples 1-5 and Comparison Examples 1-2 are shown in Table 1.

(52) TABLE-US-00001 TABLE 1 Item 10 C/1 C 20 C/1 C Capacity First reversible First coulombic Capacity Capacity retention at 1 C capacity at efficiency at retention retention after 300 Name 0.1 C (mAh/g) 0.1 C (%) (%) (%) cycles (%) Example 1 818.5 88.7 98.8 97.2 91.7 Example 2 734.8 88.5 98.6 97.0 90.8 Example 3 1025.3 89.0 97.5 96.2 89.4 Example 4 592.2 87.2 98.0 96.9 90.2 Example 5 646.7 87.6 98.7 97.1 91.8 Comparison 870.2 88.2 96.5 93.4 64.1 Example 1 Comparison 823.1 80.5 96.8 94.6 77.2 Example 2 Comparison 803.9 88.1 97.2 95.3 87.2 Example 3 Comparison 811.4 88.0 97.0 95.1 85.9 Example 4

(53) In Comparison Example 1, the nano-active material was not subjected to carbon coating, no hard carbon was added, and VC heating or kneading molding treatment was not performed; thereby, the cycle performance was greatly reduced due to severe expansion of the material resulted from the larger expansion of the nano-active material and the accumulation of the nano-active material on the soft carbon surface in large amounts.

(54) In Comparison Example 2, a soluble carbon-containing organic binder was used for replacing carbonized hard carbon, and VC heating or kneading molding treatment was not performed; thereby, more voids were present in interior, and the presence of voids resulted in an increase in side reactions of the material with the electrolyte, and the nano-active material had poor conductivity and an expansion that were not well suppressed, finally resulting in a decrease in first efficiency, and a deterioration in rate and cycle performance.

(55) In Comparison Example 3, the ratio of the median particle diameter of the soft carbon to that of the hard carbon was 1:0.5, the structure was not sufficiently optimized, and the rate and cycle performance were deteriorated.

(56) In Comparison Example 4, the ratio of the median particle diameter of the soft carbon to that of the hard carbon was 1:3.5, the structure was not sufficiently optimized, and the rate and cycle performance were deteriorated.

(57) According to the above experimental results, the high capacity rate type carbon composite anode material prepared by the method of the present application has excellent electrochemical performance, high capacity and first coulombic efficiency, and excellent rate performance.

(58) The applicant declares that the present application illustrates the detailed process equipment and process flow of the present application by the above examples, but the present application is not limited to the above detailed process equipment and process flow, that is, it does not mean that the present application must rely on the above detailed process equipment and process flow in order to be implemented.