阅读说明：本技术 一种三维C/Fe3O4锂离子电池负极材料及其制备方法 (Three-dimensional C/Fe3O4Lithium ion battery cathode material and preparation method thereof ) 是由 毕超奇 林少雄 蔡桂凡 石永倩 梁栋栋 王健 王叶 于 2020-06-18 设计创作，主要内容包括：本发明公开了一种三维C/Fe<Sub>3</Sub>O<Sub>4</Sub>锂离子电池负极材料及其制备方法,所述三维C/Fe<Sub>3</Sub>O<Sub>4</Sub>锂离子电池负极材料是以纤维素为模板,铁盐为前驱体,先通过浸渍处理将铁离子负载在模板上,再在惰性气氛下煅烧处理制得的。本发明制备的三维C/Fe<Sub>3</Sub>O<Sub>4</Sub>锂离子电池负极材料能够克服Fe<Sub>3</Sub>O<Sub>4</Sub>负极材料导电性能差以及在循环中体积变化较大的缺点,可以大幅度提升Fe<Sub>3</Sub>O<Sub>4</Sub>负极的电化学性能。(The invention discloses a three-dimensional C/Fe 3 O 4 Lithium ion battery negative electrode material and preparation method thereof, and three-dimensional C/Fe 3 O 4 The lithium ion battery cathode material is prepared by taking cellulose as a template and ferric salt as a precursor, firstly loading ferric ions on the template through impregnation treatment, and then calcining under inert atmosphere. Three-dimensional C/Fe prepared by the invention 3 O 4 The negative electrode material of the lithium ion battery can be gramClothes made of Fe 3 O 4 The defects of poor conductivity of the cathode material and large volume change in circulation can greatly improve Fe 3 O 4 Electrochemical properties of the negative electrode.)

1. Three-dimensional C/Fe₃O₄The lithium ion battery cathode material is characterized in that cellulose is used as a template, ferric salt is used as a precursor, ferric ions are loaded on the template through dipping treatment, and then the three-dimensional C/Fe is obtained through calcination treatment in inert atmosphere₃O₄A lithium ion battery cathode material.

2. Three-dimensional C/Fe of claim 1₃O₄The lithium ion battery cathode material is characterized in that the weight ratio of the cellulose to the ferric salt is 1 (0.2-7).

3. Three-dimensional C/Fe of claim 1₃O₄The lithium ion battery negative electrode material is characterized in that the cellulose is citric acid modified bacterial cellulose.

4. Three-dimensional C/Fe of claim 1₃O₄The lithium ion battery negative electrode material is characterized in that the preparation method of the citric acid modified bacterial cellulose comprises the following steps: adding the bacterial cellulose into an aqueous solution of citric acid, stirring for 30-60 min at 20-80 ℃, then washing until the pH value is 4-8, and drying to obtain the bacterial cellulose。

5. Three-dimensional C/Fe of claim 4₃O₄The lithium ion battery negative electrode material is characterized in that the weight ratio of the bacterial cellulose to the citric acid is 1 (0.2-3).

6. Three-dimensional C/Fe according to claim 4 or 5₃O₄The lithium ion battery negative electrode material is characterized in that the diameter of the bacterial cellulose is 40-60 nm.

7. Three-dimensional C/Fe according to any of claims 1-6₃O₄The lithium ion battery cathode material is characterized in that the ferric salt is a trivalent ferric salt.

8. Three-dimensional C/Fe of any of claims 1-7₃O₄The preparation method of the lithium ion battery cathode material is characterized by comprising the following steps:

s1, adding cellulose into an aqueous solution of ferric salt for dipping treatment, then filtering and drying, and repeating dipping, filtering and drying treatment for a plurality of times;

and S2, calcining the material obtained in the step S1 in an inert atmosphere, and cooling to obtain the catalyst.

9. Three-dimensional C/Fe of claim 8₃O₄The preparation method of the lithium ion battery negative electrode material is characterized in that in the step S1, the conditions of the dipping treatment are as follows: the temperature is 30-40 ℃, and the dipping time is 5-8 h.

10. Three-dimensional C/Fe of claim 9₃O₄The preparation method of the lithium ion battery negative electrode material is characterized in that in the step S2, the calcining conditions are as follows: and in a nitrogen atmosphere, raising the temperature to 300-500 ℃ at a heating rate of 3-6 ℃/min, and preserving the temperature for 1-3 h.

Technical Field

The invention relates to the technical field of lithium ion battery cathode materials, in particular to three-dimensional C/Fe₃O₄A lithium ion battery cathode material and a preparation method thereof.

Background

Compared with carbon materials, transition metal oxides (MxOy, M ═ Fe, Co, Cu, and Ti) as negative electrode materials of lithium ion batteries have higher theoretical capacity, better safety performance, and rate capability, and attract attention of people. Wherein Fe₃O₄More on account of its high theoretical capacity (927 mAhg)^-1)Highest electron conductivity (σ 2 × 10)⁴S/m is superior to other transition metal oxides), has the advantages of rich resources, no toxicity, environmental friendliness, good corrosion resistance, low cost and the like, and is favored. However, Fe₃O₄The violent volume change (more than 200%) in the charging and discharging process causes the iron to be pulverized, fall off, agglomerated and the like, even loses electric contact, and seriously hinders Fe₃O₄The lithium ion battery cathode material is practically applied.

Disclosure of Invention

Based on the technical problems in the prior art, the invention provides three-dimensional C/Fe₃O₄A lithium ion battery cathode material and a preparation method thereof, aiming at improving Fe₃O₄The negative electrode material has the defects of poor conductivity and large volume change in circulation, and improves Fe₃O₄Electrochemical properties of the negative electrode.

The invention provides three-dimensional C/Fe₃O₄The lithium ion battery cathode material is prepared by taking cellulose as a template and ferric salt as a precursor, firstly loading ferric ions on the template through impregnation treatment, and then calcining the iron ions in an inert atmosphereProcessing to obtain the three-dimensional C/Fe₃O₄A lithium ion battery cathode material.

Preferably, the weight ratio of the cellulose to the iron salt is 1 (0.2-7).

Preferably, the cellulose is citric acid modified bacterial cellulose.

Preferably, the preparation method of the citric acid modified bacterial cellulose comprises the following steps: adding the bacterial cellulose into an aqueous solution of citric acid, stirring for 30-60 min at 20-80 ℃, then washing until the pH value is 4-8, and drying to obtain the bacterial cellulose.

Preferably, the weight ratio of the bacterial cellulose to the citric acid is 1 (0.2-3).

Preferably, the diameter of the bacterial cellulose is 40-60 nm.

Preferably, the bacterial cellulose is synthesized by a microorganism of the genus acetobacter, agrobacterium rhizobium or sarcina; more preferably, the bacterial cellulose is synthesized by acetobacter xylinum.

Preferably, the iron salt is a trivalent iron salt.

The three-dimensional C/Fe₃O₄The preparation method of the lithium ion battery negative electrode material comprises the following steps:

s1, adding cellulose into an aqueous solution of ferric salt for dipping treatment, then filtering and drying, and repeating dipping, filtering and drying treatment for a plurality of times;

and S2, calcining the material obtained in the step S1 in an inert atmosphere, and cooling to obtain the catalyst.

Preferably, in step S1, the conditions of the immersion treatment are: the temperature is 30-40 ℃, and the dipping time is 5-8 h.

Preferably, in step S2, the calcining conditions are: and in a nitrogen atmosphere, raising the temperature to 300-500 ℃ at a heating rate of 3-6 ℃/min, and preserving the temperature for 1-3 h.

The invention has the following beneficial effects:

since cellulose has a three-dimensional structure, the porosity of the structure can increase the contact area between the electrolyte and the electrode surface, and the large specific surface area can promote the electricity of the electrode/electrolyte interfaceThe charge is transferred, active substances in the hole walls are in direct contact with electrolyte, so that the transmission path of ions can be reduced, the porous nano structure can easily process discrete active substance nano particles, and a small amount of binder can be used or even no binder can be used in some cases; the active substance in the large space can inhibit the volume change of the active substance in the charge and discharge process, and the porous composite material can show a second conductive phase to improve the conductivity of the battery. Therefore, the invention synthesizes three-dimensional C/Fe by taking cellulose as a template₃O₄The lithium ion battery cathode material has a three-dimensional interpenetrating network structure provided by taking cellulose as a template, has larger space and specific surface area, and can contain Fe₃O₄The volume expansion generated in the charging and discharging process effectively releases the stress, and effectively solves the problem of the traditional Fe₃O₄The problem of severe volume expansion exists; but also greatly shortens the transmission path of electrons and lithium ions and increases Fe₃O₄Contact area with electrolyte, increase utilization rate, and improve Fe₃O₄The defects of poor conductivity of the negative electrode material and large volume change in circulation effectively improve Fe₃O₄Electrochemical properties of the negative electrode.

Furthermore, the citric acid modified bacterial cellulose is selected as the template, so that the adsorption performance on metal ions can be greatly improved, the load of iron ions on the template is promoted, and the Fe content is improved₃O₄Binding capacity to three-dimensional networks, resulting in better improvement of three-dimensional C/Fe₃O₄The electrochemical performance of the lithium ion battery cathode material.

Drawings

FIG. 1 is a three-dimensional C/Fe of the present invention₃O₄The synthetic route of the lithium ion battery cathode material is shown schematically.

FIG. 2 is a three-dimensional C/Fe of the present invention₃O₄Scanning Electron Micrographs (SEM) of the lithium ion battery negative electrode material.

FIG. 3 is a three-dimensional C/Fe of the present invention₃O₄Lithium ion battery cathode material and conventional Fe₃O₄And (3) a cycle performance diagram of the lithium ion battery negative electrode material under the current density of 250 mA.

FIG. 4 is a three-dimensional C/Fe of the present invention₃O₄Lithium ion battery cathode material and conventional Fe₃O₄And (3) a rate performance diagram of the lithium ion battery cathode material.

Detailed Description

The technical solution of the present invention will be described in detail below with reference to specific examples.