WO2018028507A1

WO2018028507A1 - Method for preparing positive electrode material for aluminium ion battery

Info

Publication number: WO2018028507A1
Application number: PCT/CN2017/095880
Authority: WO
Inventors: 许志
Original assignee: 福建新峰二维材料科技有限公司
Priority date: 2016-08-07
Filing date: 2017-08-03
Publication date: 2018-02-15
Also published as: CN107706421A; CN107706421B

Abstract

Provided is a method for preparing a positive electrode material for an aluminium ion battery. The method comprises the following steps: firstly treating foam nickel using an etching method (S101); then performing a surface pre-treatment on the foam nickel (S102); then growing graphene on the surface of the foam nickel so as to form a graphene/foam nickel structure (S103); then treating the graphene/foam nickel using an etching method (S104); coating a layer of PMMA solvent on the surface of the graphene/foam nickel, and baking same into a film, so as to obtain a PMMA/graphene/foam nickel structure (S105); then performing an acid treatment on the PMMA/graphene/foam nickel, and dissolving the foam nickel, so as to obtain a PMMA/graphene structure (S106); and finally, removing the PMMA in the PMMA/graphene so as to obtain graphene based on a foam structure (S107). By chemical vapour deposition and etching technologies, the synthesis of a binder-free positive electrode material for an aluminium ion battery is realised. The material has an ultra-large capacity and a relatively low charge voltage, thereby preventing the volume expansion of the material during a charge-discharge process, and has a good cycle stability.

Description

Preparation method of positive electrode material for aluminum ion battery

Technical field

The invention relates to the technical field of aluminum ion batteries, and in particular to a method for preparing a positive electrode material for an aluminum ion battery.

Background technique

In today's energy era, it is important to develop energy storage devices with high energy density. Lithium-ion batteries (LIBs) are widely used in portable electronic products and network storage due to their relatively high discharge voltage, energy density, and good power performance. However, because of its high cost and lack of raw material lithium, new types of alternative products have emerged, such as aluminum-ion batteries. Compared with lithium-ion batteries, aluminum-ion batteries have the following characteristics: aluminum resources are abundant, low in price, and widely distributed. Aluminum-ion batteries have the advantages of safety, high performance and low cost, so they have broad application prospects in large-scale electric energy storage.

In fact, aluminum-ion batteries have long been discovered by researchers, but they cannot be used for rechargeable batteries, so their commercialization is not going well. There are three main reasons: one is poor cycle life; the other is that the charging speed is too slow and the capacity is low; thirdly, the fatal disadvantage is that the aluminum ions in the electrolyte are unstable, chemical reactions are easy to occur, and there is serious safety. Hidden dangers, these weaknesses have made aluminum-ion batteries have not been put into practical use. Therefore, in order to solve the above problems, it is necessary to find a new positive electrode material and a new stable electrolyte for the aluminum ion battery.

Summary of the invention

In view of the above problems, the present invention provides an ultra-high capacity and ultra-stable aluminum ion battery. A method of preparing a polar material.

In order to solve the above technical problem, the technical solution adopted by the present invention is: a method for preparing a positive electrode material for an aluminum ion battery, the method comprising the following steps:

Treating nickel foam by etching;

Surface pretreatment of the etched nickel foam to clean the surface and remove surface oxides;

Graphene is grown on the surface of the pretreated nickel foam to form a graphene/foam nickel structure;

Etching the graphene/foam nickel to induce the formation of nanoribbons on the surface of the graphene;

The surface of the graphene/foam nickel after the etching treatment is coated with a PMMA solvent and baked to form a PMMA/graphene/foam nickel structure;

Acid treatment of PMMA/graphene/foam nickel to fully dissolve the foamed nickel to obtain a PMMA/graphene structure;

PMMA in PMMA/graphene is removed to obtain graphene based on foam structure.

Preferably, the etching process is at least one of a plasma etching method, a chemical etching method, and a laser etching method, and the gas used in the plasma etching method is Ar, H ₂ , He, N ₂ , At least one of NH ₃ .

Preferably, the foamed nickel is subjected to Ar ⁺ plasma etching, and the nickel foam is placed in a plasma etching reactor at a selected power of 30-50 W, and the treatment time with Ar ⁺ plasma is 10-20 min.

Preferably, the nickel foam is pretreated by placing the nickel foam into a tube furnace, introducing Ar (flow rate of 300-600 sccm) and H ₂ (flow rate of 100-300 sccm), and heating to 800-1200 ° C, Annealing was carried out for 10-20 min.

Preferably, the method for growing graphene on the surface of the foamed nickel is to pass a flow of 10-30 sccm of methane into a tube furnace, and the corresponding total gas flow volume fraction is 1%-5%, and the reaction time is 10-30 minutes. Then, the sample was rapidly cooled to room temperature, and the gas atmosphere was Ar (flow rate of 300-600 sccm.) and H ₂ (flow rate of 100-300 sccm.), and the cooling rate was 200-500 ° C / min.

Preferably, the graphene/foam nickel is subjected to Ar ⁺ plasma etching, and the graphene/foam nickel is placed in a plasma etching reactor with a selected power of 20-50 w, and the processing time with Ar ⁺ plasma is 5-30min.

Preferably, the surface of the graphene/foam nickel after the etching treatment is coated with a PMMA solvent, and the PMMA is dissolved in ethyl acetate at a concentration of 4.5%, and baked at 100-120 ° C for 0.5-1 h. A PMMA/graphene/foam nickel structure was obtained.

Preferably, the acid treatment method is to immerse the obtained PMMA/graphene/foam nickel structure in a HCl solution having a concentration of 3 mol/L, the temperature is controlled at 60-80 ° C, and the soaking time is 2-3 hours.

Preferably, the PMMA removal method is to soak the PMMA/graphene in acetone at a temperature of 40-55 ° C for 0.5-1 hour, and then perform an annealing treatment under the condition that the gas used is Ar/H ₂ (80-100 sccm. The temperature is 600 ° - 700 C, and the time is 1-3 hours.

From the above description of the structure of the present invention, the present invention has the following advantages over the prior art:

1. The positive electrode material of the aluminum battery of the present invention is a three-dimensional graphene with a graphene nanopore zone, and the high porosity three-dimensional graphene foam has a large number of uniformly distributed nanopores such that AlCl ₄ - throughout the graphite positive electrode It is easier to embed and deintercalate, which not only overcomes the limited problem of graphite edge in the past, but also increases the capacity, and also achieves a lower charging threshold voltage, so that there is no side reaction in the cycle (previous charging threshold voltage is 2.45V, which is higher than the decomposition voltage of the ionic electrolyte), improves its cycle stability.

2. The invention realizes the synthesis of a binderless cathode material for an aluminum ion battery by chemical vapor deposition and etching technology, the material has a porous structure, a large specific surface area, and the graphene surface has a large number of nano-voids, and has a large capacity. At the same time, it has a lower charging voltage, and its critical voltage is only 2.3V, which can effectively avoid the decomposition of ions and avoid the volume expansion of the material during charging and discharging, so that the aluminum ion battery has excellent cycle stability and has an extremely long life.

3. Compared with the conventional electrode materials of other ion batteries, the present invention has good flexibility, can not be broken even under strong bending conditions, can maintain structural integrity, and the material does not need a binder. And the conductive agent can be directly applied to the positive electrode material of the aluminum ion battery or the flexible aluminum ion battery.

4. The aluminum ion battery prepared by the invention exhibits excellent electrochemical performance, high capacity, unique properties of fast charging and slow discharging, and excellent temperature characteristics.

DRAWINGS

The accompanying drawings, which are incorporated in the claims In the drawing:

1 is a flow chart of a method for preparing a positive electrode material for an aluminum ion battery according to the present invention;

2 is a flowchart of Embodiment 3 of the present invention;

3 is a graph showing electrochemical performance of an aluminum ion battery according to Embodiment 3 of the present invention;

4 is a graph showing performance curves of aluminum ion batteries at different temperatures according to Embodiment 3 of the present invention;

FIG. 5 is a comparison diagram of the appearance of a soft pack battery and a soft three-dimensional graphene-based soft pack battery according to the present invention after a period of charge and discharge cycles.

detailed description

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

Referring to FIG. 1, a method for preparing a positive electrode material for an aluminum ion battery, the method comprising the following steps:

S101, the foamed nickel is treated by Ar ⁺ plasma etching, and the nickel foam is placed in a plasma etching reactor, the selected power is 50w, and the processing time is 10 min with Ar ⁺ plasma;

S102, surface pre-treating the foamed nickel treated by Ar ⁺ plasma etching, placing the foamed nickel into a tube furnace, introducing Ar (flow rate of 500 sccm) and H ₂ (flow rate of 200 sccm), and heating to 1000 °C, annealing treatment for 20min, cleaning the surface and removing surface oxides;

S103, growing graphene on the surface of the pretreated nickel foam by CVD method, and passing 10sccm of methane into the tube furnace for reaction, the corresponding total gas flow volume fraction is 1.4%, the reaction time is 10 minutes, and then the sample is rapidly cooled. To room temperature, the gas atmosphere is Ar (flow rate is 500 sccm.) and H ₂ (flow rate is 200 sccm.), and the cooling rate is 300 ° C / min to form a graphene/foam nickel structure;

S104, performing Ar ⁺ plasma etching on graphene/foam nickel, and placing graphene/foam nickel into the plasma etching reactor, the selected power is 40w, and the processing time is 5-20 min with Ar ⁺ plasma. Inducing formation of nanoribbons on the surface of graphene;

S105, the surface of the graphene/foam nickel treated by Ar ⁺ plasma etching is coated with a PMMA solvent, and the PMMA is dissolved in ethyl acetate at a concentration of 4.5%, and baked at 110 ° C for 0.5 h, baked. Film formation to obtain a PMMA/graphene/foam nickel structure;

S106, acid treatment of PMMA/graphene/foam nickel, immersing the obtained PMMA/graphene/foam nickel structure in a HCl solution having a concentration of 3 mol/L, the temperature is controlled at 80 ° C, the soaking time is 3 hours, and the solution is fully dissolved. Nickel foam, obtaining PMMA/graphene structure;

S107, removing PMMA in PMMA/graphene, immersing PMMA/graphene in acetone at a temperature of 4 ° C for 1 hour, and performing annealing treatment under the condition that the gas used is Ar/H ₂ (80 sccm.). The temperature was 650 C for 2 hours, and a graphene-based graphene was obtained.

The positive electrode material of the aluminum battery of the invention is a three-dimensional graphene with a graphene nanopore zone, and the high porosity three-dimensional graphene foam has a large number of uniformly distributed nanopores so that AlCl ₄ - in the entire graphite positive electrode Easy to embed and de-embed, which not only overcomes the limited problem of graphite edge in the past, but also increases the capacity, while also achieving a lower charging threshold voltage, so that there is no side reaction in the cycle (previous charging threshold voltage is 2.45V , higher than the decomposition voltage of the ionic electrolyte), which improves the cycle stability.

The invention realizes the synthesis as a binderless cathode material for an aluminum ion battery by chemical vapor deposition and etching technology, the material has a porous structure, a large specific surface area, and the graphene surface has a large number of nano-voids, and has a large capacity, and at the same time With a lower charging voltage, the threshold voltage is only 2.3V, which can effectively avoid the decomposition of ions and avoid the volume expansion of the material during charging and discharging, so that the aluminum ion battery has excellent cycle stability and has an extremely long life.

Compared with the conventional electrode materials of other ion batteries, the material has good flexibility, can not be broken even under strong bending conditions, and can maintain the structural integrity. In addition, the material does not need adhesive and conductive. The agent can be directly applied to an aluminum ion battery or a flexible aluminum ion battery Positive electrode material.

Example 2

Referring to FIG. 1, a method for preparing a positive electrode material for an ultra-stable aluminum ion battery, the method comprising the following steps:

S101, treating the foamed nickel by Ar ⁺ plasma etching, placing the nickel foam into a plasma etching reactor, the selected power is 40w, and the processing time is 10 min with Ar ⁺ plasma to form nanometer on the pore wall of the foamed nickel. The pore zone; then the chemical nickel etching treatment of the nickel foam further increases the size of the nanopore, which is beneficial to

The diffusion of anions into the electrode material.

S102. Perform surface pretreatment on the oxidized nickel after the etching process, place the foamed nickel into a tube furnace, pass Ar (flow rate: 400 sccm) and H ₂ (flow rate: 200 sccm), heat to 1000 ° C, and anneal. After 30 minutes of treatment, the surface was cleaned and surface oxides were removed.

S103, growing graphene on the surface of the pretreated nickel foam by CVD method, and passing 20sccm of methane into the tube furnace for reaction, the corresponding total gas flow volume fraction is 1.4%, the reaction time is 10 minutes, and then the sample is rapidly cooled. To room temperature, the gas atmosphere was Ar ⁺ (flow rate of 500 sccm.) and H ₂ (flow rate of 200 sccm.), and the cooling rate was 300 ° C / min to form a graphene/foam nickel structure.

S104, Ar ⁺ plasma etching treatment of graphene/foam nickel, graphene/foam nickel is placed in a plasma etching reactor, the selected power is 40w, and the treatment time is 20 min with Ar ⁺ plasma, and induced A nanobelt is formed on the surface of the graphene.

S105, the PMMA treatment method is to coat the graphene/foam nickel surface with a layer of PMMA solvent (PMMA is dissolved in ethyl acetate, the concentration is 4.5%), and bake at 110 ° C for 1 h to obtain PMMA / graphene / Foam nickel structure.

S106, acid treatment of PMMA/graphene/foam nickel, the obtained PMMA/graphene The foamed nickel structure was immersed in a HCl solution having a concentration of 3 mol/L, the temperature was controlled at 80 ° C, and the immersion time was 3 hours, and the foamed nickel was sufficiently dissolved to obtain a PMMA/graphene structure.

S107, removing PMMA in PMMA/graphene, immersing PMMA/graphene in acetone at a temperature of 55 ° C for 0.5 hour, and then performing annealing treatment under the condition that the gas used for Ar/H ₂ (80 sccm.) is 650 C. At a time of 2 hours, a graphene-based graphene was obtained.

Example 3

Referring to FIG. 2, a method for preparing a positive electrode material for an aluminum ion battery, the method comprising the following steps:

S101. Surface pretreatment of the foamed nickel, placing the foamed nickel into a tube furnace, introducing Ar (flow rate of 500 sccm) and H ₂ (flow rate of 200 sccm), heating to 1000 ° C, annealing for 20 min, cleaning the surface and Removing surface oxides;

S102, growing graphene on the surface of the pretreated foamed nickel by CVD, and passing a 10 sccm flow of methane into the tube furnace for reaction, the corresponding total gas flow volume fraction is 1.4%, the reaction time is 10 minutes, and then the sample is rapidly cooled. To room temperature, the gas atmosphere is Ar (flow rate is 500 sccm.) and H ₂ (flow rate is 200 sccm.), and the cooling rate is 300 ° C / min to form a graphene/foam nickel structure;

S103, Ar ⁺ plasma etching treatment of graphene/foam nickel, graphene/foam nickel is placed in a plasma etching reactor, the selected power is 40w, and the processing time is 5-20 min with Ar ⁺ plasma. Inducing formation of nanoribbons on the surface of graphene;

S104, the surface of the graphene/foam nickel treated by Ar ⁺ plasma etching is coated with a PMMA solvent, and the PMMA is dissolved in ethyl acetate at a concentration of 4.5%, and baked at 110 ° C for 0.5 h, baked. Film formation to obtain a PMMA/graphene/foam nickel structure;

S105, acid treatment of PMMA/graphene/foam nickel, the obtained PMMA/graphene The foamed nickel structure is immersed in a HCl solution having a concentration of 3 mol/L, the temperature is controlled at 80 ° C, and the immersion time is 3 hours, and the foamed nickel is sufficiently dissolved to obtain a PMMA/graphene structure;

S106, removing PMMA in PMMA/graphene, immersing PMMA/graphene in acetone at a temperature of 4 ° C for 1 hour, and performing annealing treatment under the condition that the gas used is Ar/H ₂ (80 sccm.) The temperature was 650 C for 2 hours, and a graphene-based graphene was obtained.

Compared with the third embodiment, in the processes of the first embodiment and the second embodiment, before the pretreatment of the foamed nickel, a step of adding a plasma etching treatment to the nickel foam, which further increases the surface porosity of the foamed nickel, is further performed. In turn, the specific surface area is increased, thereby increasing the capacity of the aluminum ion battery.

in

During the diffusion of anion diffusion into the graphite electrode, the charge accumulated on the graphite electrode forms a built-in electric field, which prevents more

The anion further penetrates deeper into the graphite, in the same way that a boron-doped silicon wafer and a phosphorus-doped silicon wafer are placed close together to form a diode. The cut-off charging voltage is related to its self-generated potential. Thus, even if the penetration depth is limited, when the entire graphite surface is uniformly and a large number of nanopores are distributed,

Anions can diffuse and penetrate from each pore location, increasing the embedding into the entire graphite electrode

The amount of anions. Thereby greatly improving the capacity of the aluminum ion battery. Furthermore, shorter

The anion penetration distance also makes the cut-off voltage of the aluminum ion battery during charging relatively low, avoiding the electrolyte being decomposed at a high cut-off voltage, releasing the gas, and rapidly expanding the flatulence volume of the battery, resulting in poor cycle life. In summary, the three-dimensional graphene with graphene nanopore zone formed by etching technology is used as a positive electrode material for an aluminum ion battery, exhibiting high capacity, long cycle life, excellent rate performance and temperature characteristics.

Referring to Figures 3 and 4, the aluminum ion battery prepared by the present invention exhibits excellent electrochemical performance, high capacity, unique properties of fast charging and slow discharging, and excellent temperature characteristics.

Figure 3a) is a cyclic voltammetry curve of an aluminum ion battery prepared in Example 3 of the present invention, at a scanning rate of 30 mV/s, a graphene nanoribbon structure on the surface of a three-dimensional graphene foam. b) charge and discharge curves; c) cycle performance of an aluminum/graphene nanoribbon structured bag battery on the surface of a three-dimensional graphene foam at a current density of 5000 mA/g; d) soft pack batteries at 2000, 4000, 5000, 6000 , rate performance of charge and discharge at 7000 and 8000 mA/g; e) fast charge and slow discharge performance of soft pack batteries, charging at a current density of 5000 mA/g, discharging at a current density ranging from 100 to 5000 mA/g .

Figures 4a) and b) are photographs showing a graphene nanoribbon structure of an aluminum ion battery based on a high porosity three-dimensional graphene surface, which illuminate the LED indicator at 0 ° C and 80 ° C, respectively. c) Charging and discharging curves of graphene nanoribbon structured soft-packed cells on the surface of aluminum/three-dimensional graphene foam at a current density of 5000 mA/g, charge and discharge curves at different temperatures; d) and e) soft packs The cycle performance of the battery at low temperature (0 ° C) and high temperature (40, 60, and 80 ° C).

The aluminum ion battery prepared by the invention exhibits excellent electrochemical performance and has high capacity: the capacity is up to 123 mAh/g at a current density of 5000 mA/g; excellent cycle stability: no capacity decay after 10,000 cycles; In addition, there is good rate performance, and the reversible capacity at a large current density of 8000 mA/g is 111 mAh/g.

The aluminum ion battery prepared by the invention exhibits the unique performance of fast charging and slow discharging, and the battery can be charged and discharged in excess of 3700S in 80s, and the cycle stability is excellent in the use process.

The aluminum ion battery prepared by the invention has excellent temperature characteristics: high capacity at high temperature (The capacity at a current density of 5000 mA/g is constant at 123 mAh/g in the range of 20-80 ° C) and cycle stability); high coulombic efficiency (100%) and cycle stability at low temperatures.

Referring to FIG. 5, it can be seen that the three-dimensional graphene soft pack battery with a graphene nanopore strip provided by the present invention has no flatulence after 10 days of charge and discharge cycle at a large current density of 5000 mA/g; The three-dimensional graphene soft pack battery was charged and discharged for one day under the same conditions, and the battery volume expanded significantly, and the battery flatulence phenomenon was obvious. The cut-off voltage of the three-dimensional graphene with the graphene nanopore strip provided by the invention is reduced to 2.3V, which can effectively prevent the ionic electrolyte from being decomposed and avoid the flatulence phenomenon of the battery, so that the battery has good cycle stability.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

A method for preparing a positive electrode material for an aluminum ion battery, characterized in that the method comprises the following steps:

Treating nickel foam by etching;

Surface pretreatment of the etched nickel foam to clean the surface and remove surface oxides;

Graphene is grown on the surface of the pretreated nickel foam to form a graphene/foam nickel structure;

Etching the graphene/foam nickel to induce the formation of a nanopore zone on the surface of the graphene;

The surface of the graphene/foam nickel after the etching treatment is coated with a PMMA solvent and baked to form a PMMA/graphene/foam nickel structure;

Acid treatment of PMMA/graphene/foam nickel to fully dissolve the foamed nickel to obtain a PMMA/graphene structure;

PMMA in PMMA/graphene is removed to obtain graphene based on foam structure.
The method for preparing a positive electrode material for an aluminum ion battery according to claim 1, wherein the etching process is at least one of a plasma etching method, a chemical etching method, and a laser etching method, The gas used in the plasma etching method is at least one of Ar, H 2 , He, N 2 , and NH 3 .
The method for preparing a positive electrode material for an aluminum ion battery according to claim 1, wherein the foamed nickel is subjected to an Ar + plasma etching method, and the nickel foam is placed in a plasma etching reactor, and the selected power is 30-50w, treatment time with Ar + plasma is 10-20min.
The method for preparing a positive electrode material for an aluminum ion battery according to claim 1, wherein the nickel foam is pretreated by placing the nickel foam into a tubular furnace and introducing Ar (flow rate: 300-600 sccm). And H 2 (flow rate is 100-300 sccm), heated to 800-1200 ° C, and annealed for 10-20 min.
The method for preparing a positive electrode material for an aluminum ion battery according to claim 1, wherein the method for growing graphene on the surface of the foamed nickel is to pass a flow of 10-30 sccm of methane into a tubular furnace for reaction. The gas flow volume fraction is from 1% to 5%, the reaction time is from 10 to 30 minutes, and then the sample is rapidly cooled to room temperature, and the gas atmosphere is Ar (flow rate is 300-600 sccm.) and H 2 (flow rate is 100-300 sccm.). The cooling rate is 200-500 ° C / min.
The method for preparing a positive electrode material for an aluminum ion battery according to claim 1, wherein the graphene/foam nickel is subjected to Ar + plasma etching to deposit graphene/foam nickel into a plasma etching reaction. The selected power is 20-50w and the treatment time with Ar + plasma is 5-30min.
The method for preparing a positive electrode material for an aluminum ion battery according to claim 1, wherein the surface of the graphene/foam nickel after the etching treatment is coated with a PMMA solvent, and the PMMA is dissolved in ethyl acetate. The concentration was 4.5%, and baked at 100-120 ° C for 0.5-1 h to obtain a PMMA/graphene/foam nickel structure.
The method for preparing a positive electrode material for an aluminum ion battery according to claim 1, wherein the acid treatment method comprises immersing the obtained PMMA/graphene/foam nickel structure in a HCl solution having a concentration of 3 mol/L, and the temperature is Controlled at 60-80 ° C, soaking time is 2-3 hours.
The method for preparing a positive electrode material for an aluminum ion battery according to claim 1, wherein the PMMA removal method is: immersing PMMA/graphene in acetone at a temperature of 40-55 ° C for 0.5-1 hour, and then performing The annealing treatment is carried out under the conditions that the gas used has an Ar/H 2 (80-100 sccm.) temperature of 600 to 700 C for a period of 1-3 hours.