阅读说明：本技术 一种硬碳负极材料及其制备方法 (Hard carbon negative electrode material and preparation method thereof ) 是由 不公告发明人 于 2019-04-23 设计创作，主要内容包括：本发明提供了一种硬碳负极材料及其制备方法,涉及锂电池负极材料技术领域,所述制备方法包括：将玻璃钢破碎,筛分得到玻璃钢颗粒A；将颗粒A放入鼓泡床,升温,升温时颗粒A流化翻动,收集预碳化树脂颗粒B；将颗粒B浸入强碱溶液中,加热,将不溶物洗涤至中性,烘干,得到不溶物颗粒C；将颗粒C与淀粉混匀,混匀后的混合物料在惰性气氛下加热,碳化,再在惰性气氛条件下冷却至室温,得到固体D；将固体D粉碎并分级,得到硬碳负极材料；硬碳负极材料由制备方法制得。本发明所述的硬碳负极材料及其制备方法,以玻璃钢为原料,成本低,并且解决了退役风机的无害化处理问题,低成本的技术方案解决了玻璃钢内玻璃与树脂分离的难题。(The invention provides a hard carbon negative electrode material and a preparation method thereof, relating to the technical field of lithium battery negative electrode materials, wherein the preparation method comprises the following steps: crushing glass fiber reinforced plastics, and screening to obtain glass fiber reinforced plastic particles A; placing the particles A into a bubbling bed, heating, fluidizing and turning over the particles A when the temperature is raised, and collecting pre-carbonized resin particles B; immersing the particles B into a strong alkali solution, heating, washing insoluble substances to be neutral, and drying to obtain insoluble substance particles C; uniformly mixing the particles C with starch, heating the uniformly mixed mixture in an inert atmosphere, carbonizing, and cooling to room temperature in the inert atmosphere to obtain a solid D; crushing and grading the solid D to obtain a hard carbon negative electrode material; the hard carbon cathode material is prepared by the preparation method. The hard carbon cathode material and the preparation method thereof have the advantages that the glass fiber reinforced plastic is used as the raw material, the cost is low, the problem of harmless treatment of a decommissioned fan is solved, and the technical scheme with low cost solves the problem of separation of glass and resin in the glass fiber reinforced plastic.)

1. The preparation method of the hard carbon negative electrode material is characterized by comprising the following steps:

s1, crushing the glass fiber reinforced plastics, and screening to obtain glass fiber reinforced plastics particles A with the particle size of 0.5-3 mm;

s2, putting the glass fiber reinforced plastic particles A into a bubbling bed, heating to 400-600 ℃ under the inert atmosphere condition, fluidizing and turning the glass fiber reinforced plastic particles A during heating, and collecting pre-carbonized resin particles B blown out by airflow;

step S3, immersing the pre-carbonized resin particles B into a strong alkali solution, heating, washing insoluble substances until filtrate is neutral, and drying to obtain insoluble substance particles C;

step S4, uniformly mixing the insoluble particles C and starch, heating the uniformly mixed material to 900-1400 ℃ in an inert atmosphere, carbonizing the uniformly mixed material for 1-5 hours, and cooling the uniformly mixed material to room temperature in the inert atmosphere to obtain a solid D;

and step S5, crushing and grading the solid D to obtain the hard carbon negative electrode material.

2. The method for preparing the hard carbon negative electrode material is characterized in that the glass fiber reinforced plastics are taken from blades and cabins of waste wind turbines.

3. The method for preparing a hard carbon anode material according to claim 1, wherein the inert atmosphere comprises a nitrogen atmosphere, an argon atmosphere, or a helium atmosphere.

4. The preparation method of the hard carbon anode material is characterized in that the strong alkali solution comprises one or a mixture of two of sodium hydroxide and potassium hydroxide, and the mass fraction of the strong alkali solution is within a range of 30-50%.

5. The method for preparing the hard carbon negative electrode material according to claim 1, wherein in the step S2, the temperature is raised to 400-600 ℃ within 0.5-5 min under the inert atmosphere condition.

6. The method for preparing a hard carbon negative electrode material according to claim 1, wherein in step S3, the pre-carbonized resin particles B are immersed in a strong alkali solution, heated to 80-100 ℃, and reacted for 3-5 hours.

7. The method for producing a hard carbon negative electrode material according to claim 1, wherein in step S4, the mass ratio of the insoluble matter particles C to the starch when mixed is in the range of 0.2 to 2.

8. The preparation method of the hard carbon negative electrode material as claimed in claim 1, wherein in the step S4, the uniformly mixed material is heated to 900-1400 ℃ at a heating rate of 0.5-10 ℃/min in an inert atmosphere.

9. The preparation method of the hard carbon anode material according to claim 1, wherein in the step S4, the uniformly mixed material is heated in a heating furnace, and the heating furnace comprises a push plate furnace, a roller bed furnace, a mesh belt furnace, a tube furnace, a box furnace or a converter.

10. A hard carbon negative electrode material, characterized in that it is produced by the method for producing a hard carbon negative electrode material according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of lithium battery cathode materials, in particular to a hard carbon cathode material and a preparation method thereof.

Background

With the development of energy research, wind power is used as a clean energy source and is developed in a blowout mode at home and abroad. In 2018, the installed capacity of newly added wind power in the whole world reaches 51.3GW, and in the fifth year, the installed capacity exceeds 50 gigawatts. By the end of the last year, the global wind power generation capacity reaches 591 GW. When clean energy is brought by wind power generation, the treatment that the service life of a large number of wind power generation units is reached or waste wind turbines are damaged is difficult. The main parts of the fan blade, the engine room and the like are made of glass fiber reinforced plastics which are made of glass fibers with different lengths and are infiltrated by plastics such as epoxy resin, unsaturated resin and the like. The material is difficult to degrade in nature, and the treatment in deep burying and other ways can cause environmental pollution.

At present, the rapid development of electric vehicles and energy storage markets puts higher requirements on lithium batteries, and the requirements are focused on the aspects of safety performance, cycle life, quick charging performance, low-temperature performance, energy density and the like. And these properties are largely dependent on the anode material.

Graphite materials, as the most mature anode materials at present, occupy over 95 percent of the market share. From the viewpoint of material structure, since graphite has a layered structure with an interlayer spacing of about 0.334nm, lithium ions enter the interlayer space, and thus the graphite expands by about 10% in volume. If the charge rate is too fast, the effect is too severe, which can lead to flaking of the graphite and even short circuit explosions. Generally, the slow charging rate of the commercially available batteries is mainly to avoid such a risk. In addition, the graphite material is also poor in low-temperature charge and discharge properties due to problems such as electrolyte compatibility.

Accordingly, attention has been directed to other materials, such as soft carbon, hard carbon, carbon/silicon composites, metal oxides, and the like. The hard carbon material has more excellent safety performance, quick charging performance and low temperature performance. The temperature for processing the hard carbon material is generally not more than 1500 ℃, and the interlayer spacing is more than 0.38 nm. Therefore, the hard carbon material basically does not expand in volume in the charging and discharging processes, belongs to a low-strain negative electrode, and has the cycle life 3-5 times that of graphite. The hard carbon material has large interlayer spacing and more lithium embedding channels, so the fast charge and discharge performance is greatly superior to that of a graphite material, the phenomenon of lithium precipitation is not easy to occur, and the safety performance is extremely high. In addition, the hard carbon material can be compatible with low-temperature electrolyte, so that the charge and discharge functions can be realized even at-40 ℃.

At present, main production raw materials of various hard carbon materials are coconut shells, starch, asphalt, resin and other carbon-containing compounds. Each of these materials has advantages and disadvantages. Asphalt, coconut shells and other substances are low in price, but ash content is too high, so that the obtained hard carbon has poor self-discharge rate and high-temperature storage performance. The starch has low ash content and moderate price, but the carbonization rate is only about 30 percent, and the starch is used as a raw material independently, so the energy consumption is slightly higher. The resin material has low ash content and controllable structure and purity, but has higher cost than other raw materials.

Therefore, if the glass fiber reinforced plastic of the waste fan can be used as a raw material, the problem of separation of glass and resin is solved, the resin-based hard carbon material is prepared, the advantages of the resin-based hard carbon can be brought into play, the cost of the hard carbon material is obviously reduced, the problem of harmless treatment of the retired fan can be solved, and obvious benefits can be brought in the aspects of technology and products.

Disclosure of Invention

The invention solves the problems of high cost of raw materials for preparing the negative electrode material of the lithium battery, low carbonization rate and poor performance of the prepared negative electrode material in the prior art.

In order to solve the problems, the invention provides a preparation method of a hard carbon negative electrode material, which comprises the following steps:

s1, crushing the glass fiber reinforced plastics, and screening to obtain glass fiber reinforced plastics particles A with the particle size of 0.5-3 mm;

s2, putting the glass fiber reinforced plastic particles A into a bubbling bed, heating to 400-600 ℃ under the inert atmosphere condition, fluidizing and turning the glass fiber reinforced plastic particles A during heating, and collecting pre-carbonized resin particles B blown out by airflow;

step S3, immersing the pre-carbonized resin particles B into a strong alkali solution, heating, washing insoluble substances until filtrate is neutral, and drying to obtain insoluble substance particles C;

step S4, uniformly mixing the insoluble particles C and starch, heating the uniformly mixed material to 900-1400 ℃ in an inert atmosphere, carbonizing the uniformly mixed material for 1-5 hours, and cooling the uniformly mixed material to room temperature in the inert atmosphere to obtain a solid D;

and step S5, crushing and grading the solid D to obtain the hard carbon negative electrode material.

Further, the glass fiber reinforced plastics are collected from blades and cabins of waste fans.

Further, the inert atmosphere includes a nitrogen atmosphere, an argon atmosphere, or a helium atmosphere.

Further, the strong alkali solution comprises one or two of sodium hydroxide and potassium hydroxide, and the mass fraction of the strong alkali solution is within the range of 30-50%.

Further, in the step S2, the temperature is raised to 400-600 ℃ within 0.5-5 min under the inert atmosphere condition.

Further, in the step S3, the pre-carbonized resin particles B are immersed in a strong alkali solution, heated to 80 to 100 ℃, and reacted for 3 to 5 hours.

Further, in the step S4, the mass ratio of the insoluble matter particles C to the starch when kneaded is in the range of 0.2 to 2.

Further, in the step S4, the uniformly mixed material is heated to 900-1400 ℃ at a heating rate of 0.5-10 ℃/min under an inert atmosphere.

Further, in the step S4, the uniformly mixed mixture is heated in a heating furnace, where the heating furnace includes a push plate furnace, a roller bed furnace, a mesh belt furnace, a tube furnace, a box furnace or a converter.

Compared with the prior art, the preparation method of the hard carbon cathode material takes the glass fiber reinforced plastic, especially the glass fiber reinforced plastic of the waste fan as the raw material, and the starch raw material is added, so that the cost of the raw material is low, the problem of harmless treatment of the retired fan can be solved to a great extent, and remarkable benefits are brought in the aspects of cost control and environmental protection; in the pre-carbonization process, the glass fiber reinforced plastic is rapidly heated through the bubbling bed, and the effect of airflow turning is added, so that the technical scheme with low cost solves the problem of separation of glass and resin in the glass fiber reinforced plastic; according to the invention, the separated carbon material precursor is compounded with starch, and the starch is melted and invaded into the particles in the heating process, so that the pores left after the glass fibers in the raw materials are stripped are filled, the porosity and the specific surface area of the material can be obviously reduced, and the compaction density of the material and the first efficiency of the lithium battery are improved.

The invention also aims to provide a hard carbon negative electrode material prepared by the preparation method of any one of the hard carbon negative electrode materials.

When the hard carbon negative electrode material is used as a negative electrode material of a lithium battery, the capacity of the hard carbon negative electrode material reaches 400-500 mAh/g when 0.1C is discharged, the first efficiency reaches 79-87%, the capacity of the hard carbon negative electrode material still reaches 380-490 mAh/g when heavy current 10C is discharged, and good rate capability is displayed; 5C/5C rapid charging and discharging, wherein the cycle life is 4000-7000 times under the condition that the discharging depth is 95%; the capacity retention rate of 0.2C charge and discharge is 70-75% at-40 ℃, the safety is high, the cycle life is long, the low-temperature and quick charge and discharge performance is good, the preparation process is simple, and the method is suitable for mass production.

Drawings

Fig. 1 is a flow chart of a preparation method of the hard carbon negative electrode material.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

With the development of the times, large-scale equipment or buildings which are served to the deadline or need to be replaced are more around the world, wherein the problem of secondary utilization of energy is an important problem and a difficult problem facing the current time.

The glass fiber reinforced plastic is a fiber reinforced plastic, is a composite material which develops rapidly in nearly 50 years, is widely applied to various fields such as the building industry, the chemical industry, the automobile industry, the road construction, the electrical industry, the communication engineering and the like, generates huge amounts of glass fiber reinforced plastic wastes, and is a major problem in the glass fiber reinforced plastic industry at present due to the secondary utilization.

The glass fiber reinforced plastic material is a composite material which adopts glass fiber and products thereof as reinforcing materials and synthetic resin as base materials, the glass fiber is separated from the resin, the two separated materials can be respectively processed for the second time, and a new product can be prepared.

The resin is used as a carbon compound, meets the requirement of preparing raw materials of hard carbon materials, and compared with carbon compounds such as coconut shells, starch and the like, the resin separated from glass fiber reinforced plastics is low in price and also meets the time trend of material reutilization, on the premise of the purpose, the invention provides a preparation method of a hard carbon negative electrode material, which is shown in a combined figure 1 and comprises the following steps:

and step S1, coarsely crushing and crushing the glass fiber reinforced plastics to obtain glass fiber reinforced plastics particles A with small particle size. In the step, blades of the waste fan and the glass fiber reinforced plastic of the engine room are preferably detached and crushed, a screening step is added for facilitating the particle size uniformity of the prepared product, particles meeting the required particle size are screened out by a grinder in time, and the particles larger than the screened particle size are continuously ground, so that the situation that the particle size distribution is not uniform due to over-grinding, more powder is generated, and the preparation of the final product is influenced is prevented;

step S2, putting the glass fiber reinforced plastic particles A into a bubbling bed, heating to 400-600 ℃ under the inert atmosphere condition, and fluidizing and turning the glass fiber reinforced plastic particles A when heating; when the temperature reaches 400-600 ℃, the resin is subjected to polycondensation and pre-carbonization quickly; but because the properties of the glass fiber are different from those of the resin, the glass fiber can not be changed, the glass fiber and the resin after the pre-carbonization are gradually peeled off under the violent turning of the airflow, and because the riddle of the condensed pre-carbonization resin is lower than that of the glass fiber, the airflow is correspondingly controlled, the resin can be independently blown off the bubbling bed, and the pre-carbonization resin particles B blown by the airflow are collected; preferably, the blown pre-carbonized resin may be collected using a bag-type dust collector.

Separating the resin and the glass fiber is a technical difficulty in recycling the glass fiber reinforced plastic, because the resin and the glass fiber are combined very firmly. The invention adopts rapid heating pre-carbonization to ensure that the resin is shrunk and becomes fragile when being combined with the glass fiber, then the particles are turned over by hot airflow of a bubbling bed to completely strip the two materials, and the two materials are separated by the airflow by utilizing the characteristic of different densities of the two materials, thereby simply and efficiently realizing the high-efficiency separation of the glass and the resin.

Step S3, immersing the pre-carbonized resin particles B into a strong alkali solution, heating, washing insoluble substances until filtrate is neutral, and drying to obtain insoluble substance particles C; in this step, preferably, the particles B are immersed in an excess of strong alkaline solution to ensure that the glass fibers in the particles B are fully reacted and dissolved; in the step, the alkali resistance of the epoxy resin and the unsaturated resin and the corrosivity of the strong alkali solution to the glass are utilized, and the strong alkali solution with higher concentration is adopted to further remove the glass fibers mixed in the pre-carbonized resin particles B, so that the purity of the pre-carbonized resin particles is improved.

Step S4, uniformly mixing the insoluble particles C and starch, heating the uniformly mixed material to 900-1400 ℃ in an inert atmosphere, carbonizing the uniformly mixed material for 1-5 hours, and cooling the uniformly mixed material to room temperature in the inert atmosphere to obtain a solid D; in the heating process, the starch is melted after reaching the melting point and is immersed into the insoluble substance particles C, so that the pores generated after the glass fibers in the raw materials are stripped are filled, and the starch and the insoluble substance particles C are carbonized together at high temperature, the compaction density of the product is obviously improved, and the specific surface area of the product is reduced.

Step S5, crushing and grading the solid D to obtain a hard carbon negative electrode material; in the step, the obtained solid D is particles with larger particle size, and the solid D is crushed to meet the particle size requirement of the lithium battery cathode material which can be used through the steps of crushing, grading, sieving and the like, so that the final hard carbon product is obtained.

According to the preparation method of the hard carbon cathode material, the glass fiber reinforced plastics, especially the glass fiber reinforced plastics of the waste fan are used as raw materials, and the starch raw material is added, so that the raw material cost is low, the problem of harmless treatment of the retired fan can be solved to a great extent, and remarkable benefits are brought in the aspects of cost control and environmental protection; in the pre-carbonization process, the glass fiber reinforced plastic is rapidly heated through the bubbling bed, and the technical scheme of low cost solves the problem of separation of glass and resin in the glass fiber reinforced plastic through the action of airflow turning.

The lower compacted density and the first efficiency of the hard carbon material are important reasons for restricting the use of the hard carbon material, and the lower compacted density and the first efficiency of the hard carbon material are important reasons for the more pores, the lower true density, the larger specific surface and more electrolyte and lithium ions consumed for generating an SEI film during the first circulation. This patent is with resin pre-carbonization, uses hot melt starch and pre-carbonization product mix heating after that, and the pore of resin charcoal has been filled after starch melts, and this will reduce material specific surface area, promotes material true density and compaction density, generates the consumption of SEI membrane to electrolyte and lithium ion when reducing first circulation, and then improves the first efficiency of material.

The heat treatment temperature is lower than 1500 ℃ when the hard carbon cathode material is prepared, the formed product is a hard carbon structure with the interlayer spacing larger than 0.38nm, the heat treatment temperature of the product is low, the electricity charge cost of each ton of the material can be saved by more than 1 ten thousand yuan, and the manufacturing cost is greatly reduced.