CN106099089A - A kind of preparation method of anode material of lithium-ion battery biological carbon - Google Patents

Abstract

The invention discloses a method for preparing biochar for negative electrode materials of sodium ion batteries. Block B; (3) add concentrated sulfuric acid to block B and carry out homogeneous reaction to obtain reaction product C; (4) filter and dry reaction product C and transfer it to a tubular atmosphere furnace for carbonization to obtain carbonized product D (5) Soak the carbonized product D with deionized water and absolute ethanol respectively, wash and filter with suction, and then dry to obtain a negative electrode material for a sodium-ion battery with a spherical structure. The biochar prepared by the method of the invention has uniform composition, high purity and uniformly dispersed spherical structure, which can effectively shorten the diffusion path of sodium ions and improve the capacity and cycle stability of the sodium ion battery. The grapefruit peel used in the invention is green and pollution-free, can turn waste into treasure, and has a simple preparation method, low reaction temperature, short reaction time, no need for follow-up treatment, and is environmentally friendly.

Description

A kind of preparation method of biochar for sodium ion battery negative electrode material

technical field

The invention belongs to the field of preparation of negative electrode materials for sodium ion batteries, and in particular relates to a method for preparing biochar for the negative electrode materials of sodium ion batteries.

Background technique

Lithium-ion batteries are widely used in the portable electronics market due to their high energy density, long cycle life, and no memory effect. However, as industries such as vehicles and large-scale power systems rely more heavily on lithium-ion batteries, global lithium resources will not be able to effectively meet the huge demand for power lithium-ion batteries, which will further push up the prices of lithium-related materials and increase the battery capacity. cost, which ultimately hinders the development of the new energy industry. Therefore, it is critical to develop other related energy storage technologies that are inexpensive alternatives to lithium-ion batteries. Sodium reserves in the earth are 4 to 5 orders of magnitude higher than lithium, and it is widely distributed. Therefore, replacing lithium-ion batteries with sodium-ion batteries can alleviate the shortage of lithium resources. At the same time, sodium and lithium are in the same main group of the periodic table and have similar physical and chemical properties, and sodium-ion batteries have a similar working principle to lithium-ion batteries, making similar compounds used as electrodes in these two systems materials made possible. However, due to the larger radius of Na ions than Li ions, the reversible capacity and rate performance are reduced. The key to the research of sodium-ion batteries lies in the development of new high-performance electrode materials. Based on the successful experience of lithium-ion batteries, current research mainly focuses on positive electrode materials. If the research on negative electrode materials is improved, the performance of sodium-ion batteries will be greatly improved.

Grapefruit is one of the top fruits that people like to eat. It belongs to renewable resources. It is abundant in my country's Guangxi, Sichuan, Hainan and other places, and is sold all over the country. People generally only eat its meat, and the pomelo peel, which accounts for 54% to 44% of the pomelo fruit weight, is mostly discarded as waste, which not only pollutes the environment, but also wastes available resources. Grapefruit peel itself has a rich porous structure and honeycomb-like characteristics. The main components are pectin, cellulose and hemicellulose, which are the precursors for the preparation of excellent biochar. Organic matter with a larger radius can not only effectively increase the size of the material. The interlayer spacing provides conditions for the rapid transmission of sodium ions, increases the capacity of the battery, and can also form intramolecular hydrogen bonds to stabilize the structure of the material, thereby improving the cycle stability of the material. If the discarded pomelo peels can be recycled to prepare biochar for sodium-ion battery anode materials, it will not only increase the added value of pomelo, reduce battery production costs, and achieve considerable economic benefits, but also reduce the environmental impact caused by solid waste. pollute. In addition, biocarbon materials prepared from pomelo peels can also be used as lithium-ion batteries, sensors, and supercapacitors, which have a very wide range of uses and research prospects.

At present, the main method for preparing biochar is high-temperature carbonization. Lotfabad E M et al. used banana peel as raw material, reacted in a tube furnace at 1400°C for 5 hours, and then activated it with air in a tube furnace at 300°C for 3 hours, and obtained a negative electrode material for a sodium ion battery with a specific capacity of 221mAh/g [Lotfabad E M, Ding J, Cui K, et al. High-Density Sodium and Lithium Ion Battery Anodes from Banana Peels [J]. Acs Nano, 2014, 8(7): 7115-7129.]. Luo W et al. used cellulose as a raw material, reacted in a tube furnace at 1000°C for 2h, and then activated it in air at 240°C for 8h, and obtained a negative electrode material for a sodium ion battery with a specific capacity of 176mAh/g. [Luo W. Carbon nanofibers derived from cellulose nanofibers as a long-life anode material for rechargeable sodium-ion batteries[J].J.mater.chem.a,2013,1(36):10662-10666.]. Selvamani V et al. used garlic skin as raw material, pre-carbonized at 300°C, and then carbonized at 850°C for 2h, and obtained a negative electrode material for sodium-ion batteries with a specific capacity of 145mAh/g [Selvamani V, Ravikumar R, Suryanarayanan V, et al. al.Garlic peel derived high capacity hierarchical N-doped porous carbonanode for sodium/lithium ion cell[J].Electrochimica Acta,2016,190:337-345.]. The above-mentioned high-temperature carbonization method needs to be activated in the air, or the process of immersion activation is required. There are disadvantages such as high energy consumption in the reaction process, difficult control, and long reaction cycle. Therefore, a simple, easy-to-control, and rapid synthesis of biomass carbon is sought. It is of great significance to the research and development of high-performance sodium-ion battery anode materials.

Contents of the invention

The object of the present invention is to provide a kind of preparation method of biochar for the negative electrode material of sodium ion battery, to overcome the defect that the above-mentioned prior art exists, the process operation of the present invention is simple, reaction temperature is low, cycle is short, the chemical composition of obtained electrode material is uniform, Disperse evenly.

To achieve the above object, the present invention adopts the following technical solutions:

A preparation method of biochar for sodium ion battery negative electrode material, comprising the following steps:

1) Wash the pomelo peel to remove surface impurities, and cut it into uniform block A;

2) Freeze-drying the uniform block A to obtain block B;

3) adding concentrated sulfuric acid to block B to adjust the pH to 1-3, and then carry out a homogeneous reaction to obtain reaction product C;

4) After the reaction product C is suction filtered and dried, it is moved into a tubular atmosphere furnace for carbonization under inert conditions to obtain a carbonized product D;

5) The carbonization product D is soaked and washed with deionized water and ethanol, and then filtered and dried to obtain a porous spherical biochar.

Further, the diameter of the uniform block A in step 1) is 4-6mm.

Further, the freeze-drying temperature in step 2) is -9°C to -5°C, and the time is 12 to 36 hours.

Further, the concentration of concentrated sulfuric acid in step 3) is 1-5 mol·L ^-1 .

Further, the homogeneous reaction in step 3) specifically includes: raising the temperature from room temperature to 150°C-200°C at a heating rate of 6-15°C/min and keeping it warm for 12-24h, and then naturally cooling to room temperature.

Further, the carbonization in step 4) specifically includes: raising the temperature to 50° C. in a tubular atmosphere furnace for 10 minutes, raising the temperature to 500-800° C. in 75 minutes and keeping it warm for 1-3 hours, and then naturally cooling to room temperature.

Further, in step 5), the carbonized product D is soaked and washed with deionized water and ethanol, specifically: the carbonized product D is soaked in deionized water for 10 minutes, washed 5 times, and then soaked in absolute ethanol for 10 minutes, washed for 5 minutes. Second-rate.

Further, the drying temperature in step 5) is 80-110° C., and the drying time is 6-12 hours.

Compared with the prior art, the present invention has the following beneficial technical effects:

The invention uses pomelo peel as a raw material, and adopts a homogeneous phase and carbonization two-step method to prepare uniformly dispersed and uniformly sized porous spherical sodium ion battery negative electrode material biochar. The homogeneous reaction can improve the energy absorption and utilization rate of the substance, the heating is uniform and the efficiency is high, and the preparation cycle can be greatly shortened. The concentrated sulfuric acid can hydrolyze the hemicellulose, pectin and pulping cellulose in the grapefruit peel. The biochar prepared by the method of the invention has uniform composition, high purity, and uniformly dispersed spherical structure, which can effectively shorten the diffusion path of sodium ions, and improve the capacity and cycle stability of the sodium ion battery. The grapefruit peel used in the invention is green and pollution-free, can turn waste into treasure, and has a simple preparation method, low reaction temperature, short reaction time, no need for follow-up treatment, and is environmentally friendly.

Description of drawings

Fig. 1 is the scanning electron microscope (SEM) photo of the sodium-ion battery negative electrode material prepared by the embodiment of the present invention 1 biochar;

Fig. 2 is the XRD spectrum of the sodium ion battery negative electrode material prepared by the embodiment of the present invention 1～4;

Fig. 3 is the cycle performance diagram of the negative electrode materials for sodium ion batteries prepared in Examples 1 to 4 of the present invention at a current density of 50mA/g, wherein YP500 indicates that the carbonization temperature is 500°C, YP600 indicates that the carbonization temperature is 600°C, and YP700 indicates that the carbonization temperature is 600°C. The carbonization temperature is 700°C, and YP800 means that the carbonization temperature is 800°C.

detailed description

Embodiments of the present invention are described in further detail below:

A preparation method of biochar for sodium ion battery negative electrode material, comprising the following steps:

1) Wash the pomelo peel to remove surface impurities, and cut it into uniform block A with a diameter of 4-6mm;

2) Freeze-dry uniform block A at -9°C to -5°C for 12 to 36 hours to obtain block B;

3) Add concentrated sulfuric acid with a concentration of 1-5 mol·L ^-1 to block B to adjust the pH to 1-3, then raise the temperature from room temperature to 150-200°C at a heating rate of 6-15°C/min and keep it warm for 12 ~24h, then naturally cooled to room temperature to obtain reaction product C;

4) After the reaction product C is filtered and dried, it is moved into a tubular atmosphere furnace for carbonization under inert conditions. The tubular atmosphere furnace is heated to 50°C in 10 minutes, and heated to 500-800°C in 75 minutes and kept for 1-3 hours, and then naturally cooled to At room temperature, the carbonized product D was obtained;

5) Soak the carbonized product D in deionized water for 10 minutes, wash 5 times, then soak in absolute ethanol for 10 minutes, wash 5 times, then filter with suction and dry at 80-110°C for 6-12 hours to obtain a porous spherical Structural biochar.

Below in conjunction with embodiment the present invention is described in further detail:

Example 1

(1) Wash the pomelo peel to remove surface impurities, and cut it into pieces A with a diameter of 4 mm;

(2) Freeze-dry the uniform block A at a temperature of -9°C for 12 hours to obtain block B;

(3) Add 2 mol·L ^-1 concentrated sulfuric acid to block B, adjust the pH to 1, then carry out homogeneous reaction, raise the temperature from room temperature to 150°C at a heating rate of 6°C/min and keep it warm for 12h, then cool naturally To room temperature, the reaction product C is obtained;

(4) After the reaction product C was filtered and dried by suction, it was moved into a tubular atmosphere furnace for carbonization with nitrogen gas. The carbonization temperature was raised to 50°C in 10 minutes, and then to 500°C in 75 minutes. ;

(5) The carbonized product D was first soaked in deionized water for 10 min, washed 5 times, and then soaked in absolute ethanol for 10 min, washed 5 times. Then dry in a vacuum oven at 80°C for 6 hours to obtain a uniform porous spherical structure biochar.

It can be seen from Figure 1 that the biochar prepared by this method is a spherical structure with uniform dispersion and uniform size.

Example 2

(1) Wash the pomelo peel to remove surface impurities, and cut it into pieces A with a diameter of 6 mm;

(2) Freeze-dry the uniform block A at a temperature of -8°C for 18 hours to obtain block B;

(3) Add 3 mol·L ^-1 concentrated sulfuric acid to block B, adjust the pH to 2, then carry out a homogeneous reaction, raise the temperature from room temperature to 160°C at a heating rate of 8°C/min and keep it warm for 16h, then cool naturally To room temperature, the reaction product C is obtained;

(4) After the reaction product C was filtered and dried by suction, it was moved into a tubular atmosphere furnace for carbonization with nitrogen gas. The carbonization temperature was raised to 50°C in 10 minutes, and then to 600°C in 75 minutes. It was kept for 2 hours, and then naturally cooled to room temperature to obtain the carbonized product D. ;

(5) Soak the carbonized product in deionized water for 10 minutes and wash it 5 times, then soak it in absolute ethanol for 10 minutes and wash it 5 times. Then dry in a vacuum oven at 90°C for 8 hours to obtain biochar with a porous spherical structure.

Example 3

(1) Wash the pomelo peel to remove surface impurities, and cut it into pieces A with a diameter of 5 mm;

(2) Freeze-dry the uniform block A at a temperature of -7°C for 36 hours to obtain block B;

(3) Add 4 mol L ^-1 concentrated sulfuric acid to the block B, adjust the pH to 1, then carry out a homogeneous reaction, raise the temperature from room temperature to 180°C at a heating rate of 10°C/min and keep it warm for 12h, then cool naturally To room temperature, the reaction product C is obtained;

(4) After the reaction product C was filtered and dried by suction, it was transferred into a tubular atmosphere furnace for carbonization with nitrogen gas. The carbonization temperature was raised to 50°C in 10 minutes, and then to 700°C in 75 minutes. It was kept for 1 hour, and then naturally cooled to room temperature to obtain the carbonized product D. ;

(5) Soak the carbonized product in deionized water for 10 minutes and wash it 5 times, then soak it in absolute ethanol for 10 minutes and wash it 5 times. Then dry in a vacuum oven at 100° C. for 10 h to obtain porous spherical biochar.

Example 4

(1) Wash the pomelo peel to remove surface impurities, and cut it into pieces A with a diameter of 4 mm;

(2) Freeze-dry the uniform block A at a temperature of -6°C for 24 hours to obtain block B;

(3) Add 1 mol L ^-1 concentrated sulfuric acid to the block B, adjust the pH to 2, then perform a homogeneous reaction, raise the temperature from room temperature to 160°C at a heating rate of 12°C/min and keep it warm for 20h, then cool naturally To room temperature, the reaction product C is obtained;

(4) After the reaction product C was filtered and dried by suction, it was moved into a tubular atmosphere furnace for carbonization with nitrogen gas. The carbonization temperature was raised to 50°C in 10 minutes, and then to 800°C in 75 minutes. It was kept for 2 hours, and then naturally cooled to room temperature to obtain the carbonized product D. ;

(5) Soak the carbonized product in deionized water for 10 minutes and wash it 5 times, then soak it in absolute ethanol for 10 minutes and wash it 5 times. Then, it was dried in a vacuum oven at 90°C for 8 hours to obtain a porous spherical biochar.

Example 5

(1) Wash the pomelo peel to remove surface impurities, and cut it into pieces A with a diameter of 5 mm;

(2) Freeze-dry the uniform block A at a temperature of -5°C for 36 hours to obtain block B;

(3) Add 5 mol·L ^-1 concentrated sulfuric acid to block B, adjust the pH to 3, then carry out homogeneous reaction, raise the temperature from room temperature to 200°C at a heating rate of 15°C/min and keep it warm for 24h, then cool naturally To room temperature, the reaction product C is obtained;

(4) After the reaction product C was filtered and dried by suction, it was moved into a tubular atmosphere furnace for carbonization with nitrogen gas. The carbonization temperature was raised to 50°C in 10 minutes, and then to 600°C in 75 minutes. It was kept for 3 hours, and then naturally cooled to room temperature to obtain the carbonized product D. ;

(5) Soak the carbonized product in deionized water for 10 minutes and wash it 5 times, then soak it in absolute ethanol for 10 minutes and wash it 5 times. Then dry in a vacuum oven at 110° C. for 12 hours to obtain porous spherical biochar.

It can be seen from Figure 2 that samples at different carbonization temperatures have a large peak at around 2θ≈24°, which indicates that the synthesized carbon materials are composed of amorphous substances and belong to amorphous carbon materials. However, a very low peak appears at the position of 2θ≈44° in the X-ray diffraction pattern, which is similar to the peak of graphite. This shows that the synthesized carbon material belongs to amorphous carbon as a whole, but has a tendency of local graphitization. This partial graphite-like structure endows it with certain electrical conductivity. It can be seen from Figure 3 that the sodium-ion battery made of this sample at a carbonization temperature of 500-800 ° C has basically the same capacity retention rate after 500 cycles, and has a high capacity and stable cycle performance.

Claims (8)

1. the preparation method of an anode material of lithium-ion battery biological carbon, it is characterised in that comprise the following steps:

1) pomelo peel is cleaned removing surface impurity, shred to obtain homogeneous bulky A；

2) homogeneous bulky A is carried out lyophilization and obtain block B；

3) carry out homogeneous reaction after adding concentrated sulphuric acid regulation pH to 1～3 in block B, obtain product C；

4) move into carbonization under inert conditions in tube-type atmosphere furnace after being dried by product C sucking filtration, obtain carbonized product D；

5) carbonized product D is used deionized water and soak with ethanol, washing, then sucking filtration being dried, obtain mushy spherical Structure-biological carbon.

The preparation method of a kind of anode material of lithium-ion battery biological carbon the most according to claim 1, it is characterised in that Step 1) in homogeneous bulky A a diameter of 4～6mm.

The preparation method of a kind of anode material of lithium-ion battery biological carbon the most according to claim 1, it is characterised in that Step 2) in cryodesiccated temperature be-9 DEG C～-5 DEG C, the time is 12～36h.

The preparation method of a kind of anode material of lithium-ion battery biological carbon the most according to claim 1, it is characterised in that Step 3) in the concentration of concentrated sulphuric acid be 1～5mol L^-1。

The preparation method of a kind of anode material of lithium-ion battery biological carbon the most according to claim 1, it is characterised in that Step 3) in homogeneous reaction particularly as follows: and be incubated by room temperature to 150 DEG C～200 DEG C with the heating rate of 6～15 DEG C/min 12～24h, then naturally cool to room temperature.

The preparation method of a kind of anode material of lithium-ion battery biological carbon the most according to claim 1, it is characterised in that Step 4) in carbonization particularly as follows: tube-type atmosphere furnace 10min is warmed up to 50 DEG C, 75min be warmed up to 500～800 DEG C and be incubated 1～ 3h, then naturally cools to room temperature.

The preparation method of a kind of anode material of lithium-ion battery biological carbon the most according to claim 1, it is characterised in that Step 5) in use deionized water and soak with ethanol, washing particularly as follows: carbonized product D is first used deionized water carbonized product D Soak 10min, wash 5 times, use soaked in absolute ethyl alcohol 10min the most again, wash 5 times.

The preparation method of a kind of anode material of lithium-ion battery biological carbon the most according to claim 1, it is characterised in that Step 5) in be dried temperature be 80～110 DEG C, the time is 6～12h.