Aqueous zinc ion battery negative electrode material and preparation method and application thereof

Abstract

The invention provides an aqueous zinc ion battery negative electrode material as well as a preparation method and application thereof, and belongs to the technical field of aqueous zinc ion batteries. The aqueous zinc ion battery negative electrode material provided by the invention comprises a zinc substrate and a thiophene bonding layer adhered to the surface of the zinc substrate, and the thiophene bonding layer comprises thiophene monomers and an organic binder. The thiophene bonding layer is constructed on the surface of the zinc substrate, so that uniform deposition of zinc ions is ensured, dendritic crystal growth is effectively inhibited, and meanwhile, the stability of the zinc substrate and an electrolyte interface is improved, so that the cycling stability of the zinc-based negative electrode material in an aqueous zinc ion battery is improved, and the service life of the battery is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of aqueous zinc ion batteries, and in particular relates to an aqueous zinc ion battery negative electrode material and a preparation method and application thereof. Background Art

[0002] Under the general trend of "carbon peak and carbon neutrality", new energy storage technologies such as high-performance energy conversion and storage systems are the core of the new energy revolution. Lithium-ion batteries are widely used in portable electronic devices and new energy vehicles due to their low energy consumption, high specific capacity, and long life. However, problems such as limited lithium resource supply and difficult degradation of organic electrolytes have brought about environmental pollution and flammable and explosive safety hazards, which have posed a challenge to the further commercial development of lithium-ion batteries.

[0003] Aqueous zinc-ion battery is a typical secondary zinc-based battery, and its structure usually includes a positive electrode that can accommodate zinc ions, a neutral zinc salt electrolyte, and a metallic zinc negative electrode. During the battery charging and discharging process, zinc ions move back and forth between the positive and negative electrodes. The advantage of aqueous zinc-ion batteries is that the ion transfer rate of its aqueous electrolyte is about two orders of magnitude higher than that of organic electrolytes, which significantly improves the diffusion and transfer efficiency of ions. At the same time, the aqueous electrolyte itself has extremely high safety and is non-flammable. In addition, the use of aqueous electrolytes significantly reduces the manufacturing cost of batteries. Due to the stable properties of aqueous solutions and the need to isolate oxygen, the battery can also be designed as an open system, which greatly facilitates industrial-scale production. In addition, metallic zinc is abundant in reserves and low in price, which has obvious cost advantages; as a negative electrode material, zinc has a theoretical specific capacity of up to 820mAh·g -1 The redox potential is as low as -0.76 V (relative to the standard hydrogen electrode, SHE) and it exhibits good stability in aqueous solution, making it an ideal negative electrode material for aqueous batteries.

[0004] The side reactions generated by the zinc negative electrode are one of the main bottlenecks restricting the development of aqueous zinc-ion batteries. First, during the charge and discharge process, the zinc negative electrode is prone to form dendrites, which not only significantly reduce the Coulomb efficiency of the battery, but may also pierce the diaphragm, causing safety hazards such as short circuits. The formation of such dendrites is mainly caused by the uneven deposition of zinc ions on the electrode surface. Due to the uneven deposition of zinc ions during discharge, electrons tend to gather on the protrusions, resulting in a tip effect, which intensifies the growth of dendrites. Although high concentrations of zinc salts in the electrolyte can improve the stability of the battery, they will cause the conductivity of zinc ions to decrease, thereby affecting the electrochemical performance of the battery. The poor stability of the interface between the zinc negative electrode and the electrolyte is also one of the important issues restricting battery performance. Insufficient interface stability causes the zinc negative electrode to easily undergo corrosive side reactions during the cycle, such as hydrogen evolution reaction. This side reaction will not only accelerate the material loss of the zinc negative electrode, but also affect the internal stability of the battery, ultimately reducing the cycle life and stability of the battery. Therefore, how to improve the stability of the interface between the zinc negative electrode and the electrolyte and the uneven deposition of zinc ions is an urgent problem to be solved. Summary of the invention

[0005] In view of this, the object of the present invention is to provide an aqueous zinc ion battery negative electrode material and a preparation method and application thereof. The negative electrode material provided by the present invention can ensure uniform deposition of zinc ions during the cycle process, inhibit dendrite growth, and improve the stability of the interface between the zinc substrate and the electrolyte, thereby improving the cycle stability of the zinc-based negative electrode material in the aqueous zinc ion battery and extending the battery life.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The invention provides an aqueous zinc ion battery negative electrode material, comprising a zinc substrate and a thiophene bonding layer adhered to the surface of the zinc substrate, wherein the thiophene bonding layer comprises a thiophene monomer and an organic binder.

[0008] Preferably, the thickness of the thiophene adhesive layer is 50 μm to 200 μm.

[0009] Preferably, the mass ratio of the thiophene monomer to the organic binder is 1:(4-9).

[0010] Preferably, the thiophene monomers include 2,5-thiophenedicarboxylic acid, 2-thiopheneacetic acid and 4-amino-2-thiophenecarboxylic acid.

[0011] Preferably, the organic binder includes polyvinylidene fluoride and polytetrafluoroethylene.

[0012] Preferably, the zinc substrate has a thickness of 20 μm to 100 μm.

[0013] Preferably, the diameter of the zinc substrate is 10 mm to 18 mm.

[0014] The present invention also provides a method for preparing the negative electrode material of the aqueous zinc ion battery described in the above technical solution, comprising the following steps:

[0015] The thiophene monomer, the organic binder and N-methylpyrrolidone are mixed to obtain a slurry.

[0016] The slurry is coated on the surface of a zinc substrate and dried to obtain the aqueous zinc ion battery negative electrode material.

[0017] Preferably, the mass concentration of the thiophene monomer in the slurry is 160 mg·mL -1 ~250mg·mL -1 .

[0018] The present invention also provides the use of the negative electrode material of the aqueous zinc ion battery described in the above technical solution or the negative electrode material of the aqueous zinc ion battery prepared by the preparation method described in the above technical solution in an aqueous zinc ion battery, wherein the negative electrode material is used for the aqueous zinc ion battery at a current density of 1 mA·cm -2 ~10 mA cm -2 , capacity is 1 mAh cm -2 ~5mAh·cm -2 When the half-cell average coulombic efficiency is 99.2% to 99.7%.

[0019] The present invention provides an aqueous zinc ion battery negative electrode material, comprising a zinc substrate and a thiophene bonding layer adhered to the surface of the zinc substrate, wherein the thiophene bonding layer comprises a thiophene monomer and an organic binder. The present invention constructs a thiophene bonding layer with strong strain resistance on the surface of the zinc substrate, which can directly avoid direct contact between the zinc substrate and the electrolyte, thereby avoiding severe interfacial reactions and corrosion, and improving the stability of the interface between the zinc substrate and the electrolyte; on the other hand, there is an interaction between S and Zn in the thiophene functional group, which plays an important role in regulating zinc ions, can effectively regulate the zinc ion flux, thereby ensuring uniform deposition of zinc ions, and effectively inhibiting dendrite growth, thereby improving the cycle stability of the zinc-based negative electrode material in the aqueous zinc ion battery and extending the battery life. Experimental results show that the aqueous zinc ion battery negative electrode material provided by the present invention has a current density of 1 mA·cm -2 ~5mA·cm -2 , capacity is 1 mAh cm -2 When the half-cell has an average coulombic efficiency of 99.26% to 99.55%, the cycle life is 195h to 1000h.

[0020] At the same time, the preparation method provided by the present invention is simple to operate and low in cost. By adopting simple coating, a negative electrode material with good cycle stability in an aqueous zinc ion battery can be prepared, which is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0022] Figure 1 It is a comparison chart of the cycle performance of the symmetrical batteries prepared in Example 2 and Comparative Example 3.

[0023] Figure 2 It is a comparison chart of the cycle performance of the symmetrical batteries prepared in Examples 1 to 3 and Comparative Examples 1 to 2. DETAILED DESCRIPTION

[0024] The invention provides an aqueous zinc ion battery negative electrode material, comprising a zinc substrate and a thiophene bonding layer adhered to the surface of the zinc substrate, wherein the thiophene bonding layer comprises a thiophene monomer and an organic binder.

[0025] In the present invention, the thickness of the thiophene bonding layer is preferably 50 μm to 200 μm, more preferably 70 μm to 150 μm, and most preferably 100 μm. In the present invention, a thicker thiophene bonding layer can prevent the zinc substrate from directly contacting the electrolyte to a greater extent, but it will slow down the migration rate of zinc ions and reduce the number of zinc ion transmissions, while a thinner thiophene bonding layer can speed up the migration rate of ions, but the uniformity of zinc ions, corrosion protection and dendrite inhibition effects are not ideal.

[0026] In the present invention, the mass ratio of the thiophene monomer to the organic binder is preferably 1:(4-9), more preferably 1:(4-6). In the present invention, the mass ratio of the thiophene monomer to the organic binder can effectively bind the electrode material particles together and firmly adhere them to the current collector to form a stable electrode structure. If the ratio is too high, the active sites of the electrode material will be over-covered, reducing their utilization rate; if the ratio is too low, the electrode structure may be loose and easy to fall off during the charge and discharge process, affecting the cycle stability of the battery.

[0027] In the present invention, the thiophene monomers preferably include 2,5-thiophenedicarboxylic acid, 2-thiopheneacetic acid and 4-amino-2-thiophenecarboxylic acid. The present invention has no particular limitation on the source of the thiophene monomers, and commercial products known in the art can be used.

[0028] In the present invention, the organic binder preferably includes polyvinylidene fluoride and polytetrafluoroethylene, and more preferably polyvinylidene fluoride. The present invention has no particular limitation on the source of the organic binder, and commercially available products known in the art can be used.

[0029] In the present invention, the zinc substrate is preferably zinc foil; the thickness of the zinc substrate is preferably 20 μm to 100 μm, more preferably 30 μm to 70 μm; the diameter of the zinc substrate is preferably 10 mm to 18 mm, more preferably 12 mm to 16 mm.

[0030] The present invention also provides a method for preparing the negative electrode material of the aqueous zinc ion battery described in the above technical solution, comprising the following steps:

[0031] The thiophene monomer, the organic binder and N-methylpyrrolidone are mixed to obtain a slurry.

[0032] The slurry is coated on the surface of a zinc substrate and dried to obtain the aqueous zinc ion battery negative electrode material.

[0033] The invention mixes thiophene monomers, an organic binder and N-methylpyrrolidone to obtain slurry.

[0034] The present invention has no particular limitation on the source of the N-methylpyrrolidone, and any commercially available product known in the art may be used.

[0035] In the present invention, the mass concentration of the thiophene monomer in the slurry is preferably 160 mg·mL -1 ~250mg·mL -1 . In the present invention, the mass concentration can promote the uniform polymerization of thiophene monomers on the electrode surface to form a dense and uniform protective layer, thereby improving the electrochemical activity of the electrode. If the mass concentration is too low, it is difficult to form an effective polymer film, and the protective layer on the electrode surface is incomplete, resulting in insufficient electrochemical activity; if the mass concentration is too high, the polymer film may be too thick, hindering the transmission of electrons and ions, and reducing the electrochemical activity.

[0036] In the present invention, the mixing time is 8 hours to 16 hours, and the mixing method is preferably stirring. The present invention has no special limitation on the stirring rate, as long as the thiophene monomer, organic binder and N-methylpyrrolidone can be evenly mixed.

[0037] After obtaining the slurry, the present invention coats the slurry on the surface of the zinc substrate and dries it to obtain the aqueous zinc ion battery negative electrode material.

[0038] In the present invention, the coating is preferably carried out in a coating machine. The present invention has no particular limitation on the coating amount of the coating, as long as the desired thickness of the thiophene bonding layer can be obtained.

[0039] In the present invention, the drying time is preferably 8 hours to 16 hours, and the drying method is preferably vacuum drying. The present invention has no particular limitation on the conditions of the vacuum drying, as long as the coated slurry can be dried.

[0040] In the present invention, after the drying is completed, the dried product is preferably dried. The present invention has no special limitation on the conditions and methods of the drying, and conventional drying conditions and methods in the art can be used.

[0041] The present invention also provides the use of the negative electrode material of the aqueous zinc ion battery described in the above technical solution or the negative electrode material of the aqueous zinc ion battery prepared by the preparation method described in the above technical solution in an aqueous zinc ion battery, wherein the negative electrode material is used for the aqueous zinc ion battery at a current density of 1 mA·cm -2 ~10mA·cm -2 , capacity is 1 mAh cm -2 ~5mAh·cm -2 When the half-cell average coulombic efficiency is 99.2% to 99.7%.

[0042] The aqueous zinc ion battery negative electrode material provided by the present invention, its preparation method and application are described in detail below in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0043] Example 1

[0044] 40 mg of polyvinylidene fluoride and 160 mg of 2,5-thiophenedicarboxylic acid were dissolved in 1 mL of N-methylpyrrolidone and stirred for 12 h to obtain a slurry.

[0045] The obtained slurry was coated on the surface of zinc foil (30 μm thick, 12 mm in diameter) by using a coating machine. The coating thickness of the zinc foil surface was 50 μm. After vacuum drying for 12 hours, it was dried to obtain the negative electrode material.

[0046] The prepared negative electrode materials were assembled into half-cells and symmetrical cells, wherein the electrolyte was 2M ZnSO4 and the separator was glass fiber. -2 , capacity is 1 mAh cm -2 The average coulombic efficiency of the half-cell is 99.42%. The assembled symmetrical battery is subjected to cycle performance test. The test results are as follows Figure 2 As shown. At a current density of 5 mA cm -2 , capacity is 1 mAh cm -2 The cycle life is 195h.

[0047] Example 2

[0048] 40 mg of polyvinylidene fluoride and 160 mg of 2,5-thiophenedicarboxylic acid were dissolved in 1 mL of N-methylpyrrolidone and stirred for 12 h.

[0049] The obtained slurry was coated on the surface of zinc foil (30 μm thick, 12 mm in diameter) by using a coating machine. The coating thickness of the zinc foil surface was 100 μm. After vacuum drying for 12 hours, the negative electrode material was obtained by drying.

[0050] The prepared negative electrode materials were assembled into half-cells and symmetrical cells, wherein the electrolyte was 2M ZnSO4 and the separator was glass fiber. -2 , capacity is 1 mAh cm -2 The average coulombic efficiency of the half-cell is 99.55%. The assembled symmetrical battery is subjected to cycle performance test. The test results are as follows Figure 1 As shown. At a current density of 1 mA·cm -2 , capacity is 1 mAh cm -2 The cycle life is 900h.

[0051] Example 3

[0052] 40 mg of polyvinylidene fluoride and 160 mg of 2,5-thiophenedicarboxylic acid were dissolved in 1 mL of N-methylpyrrolidone and stirred for 12 h to obtain a slurry.

[0053] The obtained slurry was coated on the surface of zinc foil (30 μm thick, 12 mm in diameter) by using a coating machine. The coating thickness of the zinc foil surface was 200 μm. After vacuum drying for 12 h, the negative electrode material was obtained by drying.

[0054] The prepared negative electrode materials were assembled into half-cells and symmetrical cells, wherein the electrolyte was 2M ZnSO4 and the separator was glass fiber. -2 , capacity is 1 mAh cm -2 The average coulombic efficiency of the half-cell is 99.26%. The assembled symmetrical battery is subjected to a cycle performance test. The test results are as follows Figure 2 As shown. At a current density of 5 mA cm -2 , capacity is 1 mAh cm -2 The cycle life is 230h.

[0055] Example 4

[0056] 40 mg of polyvinylidene fluoride and 160 mg of 2-thiopheneacetic acid were dissolved in 1 mL of N-methylpyrrolidone and stirred for 12 h to obtain a slurry.

[0057] The obtained slurry was coated on the surface of zinc foil (30 μm thick, 12 mm in diameter) by using a coating machine. The coating thickness of the zinc foil surface was 100 μm. After vacuum drying for 12 hours, the negative electrode material was obtained by drying.

[0058] The prepared negative electrode materials were assembled into a symmetrical battery, wherein the electrolyte was 2M ZnSO4 and the separator was glass fiber. The assembled symmetrical battery was subjected to a cycle performance test at a current density of 2 mA cm -2 , capacity is 1 mAh cm -2 The cycle life is 800h.

[0059] Example 5

[0060] 40 mg of polyvinylidene fluoride and 160 mg of 4-amino-2-thiophenecarboxylic acid were dissolved in 1 mL of N-methylpyrrolidone and stirred for 12 h to obtain slurry.

[0061] The obtained slurry was coated on the surface of zinc foil (30 μm thick, 12 mm in diameter) by using a coating machine. The coating thickness of the zinc foil surface was 100 μm. After vacuum drying for 12 hours, the negative electrode material was obtained by drying.

[0062] The prepared negative electrode materials were assembled into a symmetrical battery, wherein the electrolyte was 2M ZnSO4 and the separator was glass fiber. The assembled symmetrical battery was subjected to a cycle performance test at a current density of 2 mA cm -2 , capacity is 1 mAh cm -2 The cycle life is 1000h.

[0063] Comparative Example 1

[0064] 40 mg of polyvinylidene fluoride and 160 mg of 2,5-thiophenedicarboxylic acid were dissolved in 1 mL of N-methylpyrrolidone and stirred for 12 h to obtain a slurry.

[0065] The obtained slurry was coated on the surface of zinc foil (30 μm thick, 12 mm in diameter) by using a coating machine. The coating thickness of the zinc foil surface was 25 μm. After vacuum drying for 12 hours, the negative electrode material was obtained by drying.

[0066] The prepared negative electrode material was assembled into a symmetrical battery, wherein the electrolyte was 2M ZnSO4 and the separator was glass fiber. The assembled symmetrical battery was subjected to a cycle performance test, and the test results were as follows: Figure 2 As shown. At a current density of 5 mA cm -2 , capacity is 1 mAh cm -2 The cycle life is 152h.

[0067] Comparative Example 2

[0068] 40 mg of polyvinylidene fluoride and 160 mg of 2,5-thiophenedicarboxylic acid were dissolved in 1 mL of N-methylpyrrolidone and stirred for 12 h to obtain slurry.

[0069] The obtained slurry was coated on the surface of zinc foil (30 μm thick, 12 mm in diameter) by using a coating machine. The coating thickness of the zinc foil surface was 250 μm. After vacuum drying for 12 h, the negative electrode material was obtained by drying.

[0070] The prepared negative electrode material was assembled into a symmetrical battery, wherein the electrolyte was 2M ZnSO4 and the separator was glass fiber. The assembled symmetrical battery was subjected to a cycle performance test, and the test results were as follows: Figure 2 As shown. At a current density of 5 mA cm -2 , capacity is 1 mAh cm -2 The cycle life is 179h.

[0071] Comparative Example 3

[0072] Zinc foil (30 μm thick, 12 mm in diameter) was assembled into a symmetrical battery, where the electrolyte was 2M ZnSO4 and the separator was glass fiber. The assembled symmetrical battery was subjected to a cycle performance test, and the test results are shown in the figure. Figure 1 As shown. At a current density of 5 mA cm -2 , capacity is 1 mAh cm -2 The cycle life is 25h.

[0073] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A negative electrode material for an aqueous zinc ion battery, characterized in that: The invention comprises a zinc substrate and a thiophene bonding layer adhered to the surface of the zinc substrate, wherein the thiophene bonding layer comprises a thiophene monomer and an organic bonding agent.

2. The negative electrode material according to claim 1, characterized in that The thickness of the thiophene adhesive layer is 50 μm to 200 μm.

3. The negative electrode material according to claim 1, characterized in that The mass ratio of the thiophene monomer to the organic binder is 1:(4-9).

4. The negative electrode material according to claim 1 or 3, characterized in that: The thiophene monomers include 2,5-thiophenedicarboxylic acid, 2-thiopheneacetic acid and 4-amino-2-thiophenecarboxylic acid.

5. The negative electrode material according to claim 1 or 3, characterized in that: The organic binder includes polyvinylidene fluoride and polytetrafluoroethylene.

6. The negative electrode material according to claim 1, characterized in that The thickness of the zinc substrate is 20 μm to 100 μm.

7. The negative electrode material according to claim 1 or 6, characterized in that: The diameter of the zinc substrate is 10 mm to 18 mm.

8. The method for preparing the negative electrode material for aqueous zinc ion batteries according to any one of claims 1 to 7, characterized in that: The following steps are involved: The thiophene monomer, the organic binder and N-methylpyrrolidone are mixed to obtain a slurry. The slurry is coated on the surface of a zinc substrate and dried to obtain the aqueous zinc ion battery negative electrode material.

9. The preparation method according to claim 8, characterized in that: The mass concentration of the thiophene monomer in the slurry is 160 mg·mL -1 ~250mg·mL -1 .

10. Use of the negative electrode material for aqueous zinc ion batteries according to any one of claims 1 to 7 or the negative electrode material for aqueous zinc ion batteries prepared by the preparation method according to claim 8 or 9 in aqueous zinc ion batteries, characterized in that: At a current density of 1 mA cm -2 ~10mA·cm -2 , capacity is 1 mAh cm -2 ~5mAh·cm -2 When the half-cell average coulombic efficiency is 99.2% to 99.7%.

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