Preparation method and application of high-performance aqueous alkaline reversible high-voltage zinc ion battery electrolyte
Technical Field
The invention belongs to the field of aqueous alkaline zinc ion secondary batteries, and particularly relates to a relevant technology and application of aqueous alkaline reversible high-voltage zinc ion battery electrolyte.
Background
Organic lithium ion batteries are currently the most competitive secondary energy storage devices with high energy density and voltage platforms, and have been commercially applied in various fields such as electronic products and electric automobiles. However, expensive and scarce raw materials such as lithium carbonate and metallic lithium, and inflammable organic electrolytes, lead to a rapid increase in manufacturing costs of lithium ion batteries and raise serious safety problems, and thus development of new non-lithium battery technologies is attracting attention. In recent years, the aqueous chargeable alkaline zinc ion battery is expected to become a novel electrochemical energy storage device for large-scale commercial application because of the advantages of excellent environmental compatibility, good intrinsic safety, abundant zinc ore raw material reserves, low cost of electrolyte and the like. In aqueous rechargeable alkaline zinc-ion battery systems, metallic zinc exhibits a suitable redox potential (-0.76V vs. standard hydrogen electrode, SHE), an ideal theoretical specific capacity (820 mAh g -1 ,5855 mAh cm -3 ) And conductivity is formed byIs one of the most promising negative electrode materials.
However, dendrite formation and hydrogen evolution side reactions of zinc cathodes in alkaline electrolytes are very troublesome problems during the charge and discharge of aqueous rechargeable alkaline zinc-ion batteries. Due to OH in the electrolyte - For Zn 2+ Has a strong affinity, so that the charge carriers of the system are in the form of highly soluble zincate complexes (e.g. [ Zn (OH) 4 ] 2− ) In the form of a gel. However, thermodynamic instability and local supersaturation result in zincate complexes tending to convert to needle-like dendrites containing non-conductive ZnO at the anode surface, thereby rendering the zinc metal anode ineffective. According to the Poubaix plot, the hydrogen evolution potential (E H2/H2O = -0.83 v, she) is higher than the reduction potential of zinc, so the reduction process of zinc is inevitably accompanied by (HER), which aggravates the uneven distribution of zinc species and corrosion and passivation of the negative electrode surface. On the other hand, under high pressure, the competitive hydrogen evolution and oxygen production of the alkaline electrolyte seriously damages the surface stability of the cathode material and accelerates the structural collapse, and finally limits the voltage range of the zinc-based energy storage device, thus preventing the improvement of energy density.
The invention introduces a high-efficiency glycine electrolyte additive to overcome the technical defects of the existing alkaline zinc ion battery. On the one hand, the electrolyte optimization strategy has the advantages of simple modification flow, low cost, less additive consumption and high repeatability, and the glycine has the non-toxic and harmless nature, so that the electrolyte optimization strategy is an environment-friendly electrolyte additive capable of meeting the requirement of mass production. Gly derived from glycine, on the other hand - Contention priority over H 2 O molecules are adsorbed on the metallic zinc anode so as to effectively regulate and control the electric double layer on the surface of the anode and assist [ Zn (OH) 4 ] 2− To prevent uncontrolled radial diffusion thereof, which inhibits the occurrence of side reactions such as dendrite formation, corrosion and passivation to a certain extent, and matches high pressure Ni x Co (1-x)/ 2 Mn (1-x)/2 O 2 The positive electrode assembled water system alkaline reversible high-voltage zinc ion full battery shows excellent electrochemical performance.
Disclosure of Invention
The invention aims to provide a preparation method and application of a high-performance aqueous alkaline reversible high-voltage zinc ion battery electrolyte, and aims to improve the cycling stability of a zinc metal negative electrode and a high-voltage resistant positive electrode in the alkaline electrolyte, so that the electrochemical performance of the whole alkaline reversible high-voltage zinc ion battery is improved. In order to achieve the above purpose, the invention adopts the following technical scheme:
(1) Completely dissolving the alkaline salt solid in deionized water under the assistance of ultrasonic waves, and cooling to room temperature to obtain an alkaline salt solution with the concentration of 1-6 mol L -1 ;
(2) Adding the glycine additive into the alkaline salt solution, and stirring until the solution is clear and transparent to prepare an aqueous alkaline mixed electrolyte;
(3) The preparation method of the aqueous alkaline reversible high-voltage zinc ion full battery comprises the following steps: zinc foil is used as a negative electrode, nickel cobalt manganese composite oxide (supplied by Shenzhen Hua fresh materials science and technology Co., ltd.) is used as a positive electrode material, glass fiber is used as a diaphragm, and the aqueous alkaline mixed electrolyte containing glycine additive is introduced to assemble the button secondary battery (CR 2025 type).
The alkaline salt described in the above step (1) includes, but is not limited to, potassium hydroxide, sodium hydroxide, lithium hydroxide, etc.; the pH range of the resulting alkaline salt solution was: 12-14.
The optimal concentration of the glycine additive in the step (2) is 0.02-0.5 mol L -1 Gly derived from alkaline electrolyte - Preferential to H 2 O molecules are adsorbed on the metallic zinc cathode to inhibit H 2 O decomposition and effective control of the electric double layer on the surface of the negative electrode to assist [ Zn (OH) 4 ] 2− To hinder the uncontrolled radial diffusion thereof, which to a certain extent inhibits the occurrence of side reactions such as dendrite formation, corrosion and passivation;
the aqueous alkaline reversible high-voltage zinc ion full battery in the step (3) adopts a zinc foil cathode with the thickness of 50-250 mu m; the volume of the electrolyte is 30-120 mu L, and the glass fiber diaphragm is Whatman GF/D or Whatman GF/A;
further, the positive electrode material in the step (3) has an active material of 70 wt% nickel cobalt manganese composite oxide, a conductive agent of 20 wt% acetylene black, a binder of 10 wt% polyvinylidene fluoride, and is mixed in N-methylpyrrolidone solvation, the positive electrode material is obtained after ball milling for 1 hour, the positive electrode material is coated on a carbon cloth current collector and vacuum drying is carried out at 80 ℃ for 10 hours to prepare a positive electrode sheet, wherein the mass load of the active material nickel cobalt manganese composite oxide is 1.0-10.0 mg cm -2 The method comprises the steps of carrying out a first treatment on the surface of the Wherein the molecular formula of the nickel-cobalt-manganese composite oxide positive electrode material is Ni x Co (1-x)/2 Mn (1-x)/2 O 2 Wherein X is more than or equal to 0.5 and less than or equal to 0.8.
The application of the aqueous alkaline reversible high-voltage zinc ion battery electrolyte prepared by the preparation method is characterized in that zinc foil is used as a negative electrode, the prepared nickel-cobalt-manganese composite oxide is used as a positive electrode material, glass fiber is used as a diaphragm, and the aqueous alkaline mixed electrolyte prepared by the preparation method is introduced to assemble a button secondary battery (CR 2025 type).
Compared with the prior art, the invention has the following specific advantages:
(1) The electrolyte additive is used as a modification method for improving the performance of the zinc ion battery, and has simple operation and obvious effect.
(2) Glycine as additive has low cost, high safety, no toxicity and no harm, and is environment friendly.
(3) According to the invention, glycine is introduced into the alkaline electrolyte, and is self-ionized into glycine anions, wherein the anions have strong zinc affinity, have higher adsorption energy than water molecules on the surface of a zinc negative electrode, and can prevent the water molecules and the metal zinc negative electrode from generating hydrogen evolution side reaction. In addition, the additive can optimize the structure and composition of the double electric layer on the surface of the zinc cathode, expand the width of the double electric layer, reduce the repulsive force and extremely poor concentration of active substances in the double electric layer and obstruct Zn (OH) 4 2- Local high concentration and uncontrollable lateral diffusion on the surface of the zinc cathode promote the metal zinc cathode to show excellent reversibility in potassium hydroxide-glycine alkaline electrolyte, and zinc battery circulationThe ring life is prolonged by 50 times.
(4) Glycine additive has good practicability in alkaline reversible high-voltage zinc ion energy storage equipment, and Zn Ni is assembled by using potassium hydroxide-glycine mixed alkaline electrolyte 0.8 Co 0.1 Mn 0.1 O 2 The cycle reversibility and the multiplying power performance of the full battery are obviously improved. Specifically, zn Ni 0.8 Co 0.1 Mn 0.1 O 2 The battery is at 0.3A g -1 Can be stably circulated for 100 times under the condition, and the reversible specific capacity is up to 182 mAh g -1 In 1A g -1 The cycle life reaches 300 times under the condition of providing 106 mAh g of average reversible specific capacity -1 While maintaining a high discharge voltage plateau of 1.6V.
Drawings
FIG. 1 is a mixed alkaline electrolyte obtained in example 1 and 3 mol L -1 Linear sweep voltammogram of potassium hydroxide alkaline electrolyte tested in a three electrode system.
FIG. 2 is a mixed alkaline electrolyte obtained in example 1 and 3 mol L -1 The potassium hydroxide alkaline electrolyte is used for preparing the XRD pattern of the zinc electrode after circulation after the Zn symmetric battery is assembled.
FIG. 3 is a mixed alkaline electrolyte obtained in example 1 and 3 mol L -1 And (3) the potassium hydroxide alkaline electrolyte is used for preparing an SEM image of the recycled zinc electrode after assembling the Zn symmetric battery.
FIG. 4 is an assembly of the mixed alkaline electrolyte obtained in example 1 into Zn Ni 0.8 Co 0.1 Mn 0.1 O 2 And (3) multiplying power performance diagram of full battery.
FIG. 5 shows the assembly of Zn Ni into the mixed alkaline electrolyte obtained in example 1 0.8 Co 0.1 Mn 0.1 O 2 Full cell at 0.3A g -1 Constant current cycling performance plot at current density.
FIG. 6 shows the assembly of Zn Ni into the mixed alkaline electrolyte obtained in example 1 0.8 Co 0.1 Mn 0.1 O 2 Full cell at 1A g -1 Constant current cycling performance plot at current density.
FIG. 7 is a diagram of the process of example 1The mixed alkaline electrolyte is assembled into Zn Ni 0.8 Co 0.1 Mn 0.1 O 2 Full cell at 1A g -1 Charge-discharge curve at current density.
Detailed Description
The positive electrode sheet Ni of the nickel-cobalt-manganese composite oxide used in the following examples of the present invention 0.8 Co 0.1 Mn 0.1 O 2 Is prepared by the following method: mixing 70 wt% nickel cobalt manganese composite oxide (supplied by Shenzhen Hua fresh materials science and technology Co., ltd.), 20. 20 wt% acetylene black and 10. 10 wt% polyvinylidene fluoride in N-methyl pyrrolidone solvent, ball milling for 1 hour to obtain positive electrode slurry, coating the positive electrode slurry on a carbon cloth current collector, and vacuum drying at 80 ℃ for 10 hours to obtain a positive electrode plate, wherein the mass load of the active material nickel cobalt manganese composite oxide is 1.0-10.0 mg cm -2 . The molecular formula of the nickel-cobalt-manganese composite oxide positive electrode material is Ni x Co (1-x)/2 Mn (1-x)/2 O 2 Wherein 0.5.ltoreq.X.ltoreq.0.8, preferably Ni 0.8 Co 0.1 Mn 0.1 O 2 。
Example 1
1) Completely dissolving potassium hydroxide solid in deionized water with the aid of ultrasonic wave, cooling to room temperature to obtain potassium hydroxide solution with concentration of 3 mol L -1 Adding glycine additive into the potassium hydroxide solution, stirring until the solution is clear and transparent, wherein the concentration ratio of potassium hydroxide to glycine is 3 mol L -1 :0.08 mol L -1 The aqueous potassium hydroxide-glycine alkaline mixed electrolyte is prepared.
2) In a three-electrode test system, the potassium hydroxide-glycine alkaline mixed electrolyte prepared in the step 1) is introduced, ag/AgCl is used as a reference electrode, and zinc foil is used as a linear sweep voltammogram of a counter electrode and a working battery test electrolyte. FIG. 1 shows the mixed alkaline electrolyte obtained in example 1 and 3 mol L -1 The linear sweep voltammogram of the alkaline electrolyte of potassium hydroxide in a three-electrode system shows that after the glycine additive is introduced into the alkaline electrolyte of potassium hydroxide, the hydrogen evolution potential is increased, which proves that the glycine additive can obviously inhibitThe hydrogen evolution reaction on the surface of the electrode is generated, and the stable voltage window of the electrolyte is widened.
3) And (3) introducing the potassium hydroxide-glycine alkaline mixed electrolyte prepared in the step (1), taking zinc foil as an electrode, taking Whatman GF/D as a diaphragm, and assembling the Zn symmetric battery. FIG. 2 shows a zinc electrode obtained in example 1 in combination with an alkaline electrolyte and 3 mol L -1 XRD pattern of potassium hydroxide alkaline electrolyte after circulation was found to be 3 mol L -1 The zinc reduction reaction in the potassium hydroxide electrolyte is accompanied by the formation of ZnO as a byproduct, which irreversibly consumes the zinc active material and the electrolyte, while no ZnO diffraction peak occurs in the potassium hydroxide-glycine alkaline mixed electrolyte. As can be seen by further combining the SEM results of FIG. 3, the molecular weight of the catalyst was determined to be 3 mol L -1 Electrochemical deposition/stripping is carried out in potassium hydroxide electrolyte, and the defect of dendrite formation and loose and porous pores on the surface of the zinc electrode is avoided when the electrochemical deposition/stripping is carried out in potassium hydroxide-glycine alkaline mixed electrolyte, which is favorable for proving that the introduction of glycine in potassium hydroxide can effectively protect the surface of the electrode and regulate [ Zn (OH)] 2- Preventing local supersaturation thereof and further inhibiting the formation of dendrites and by-product ZnO.
4) Based on the principle, the potassium hydroxide-glycine alkaline mixed electrolyte is introduced, zinc foil is taken as a negative electrode, and nickel cobalt manganese composite oxide (Ni 0.8 Co 0.1 Mn 0.1 O 2 ) As the positive electrode material, whatman GF/D is assembled into Zn Ni for the diaphragm 0.8 Co 0.1 Mn 0.1 O 2 Full cell (CR 2025 type). Zn Ni after glycine additive is introduced 0.8 Co 0.1 Mn 0.1 O 2 The high voltage full cell exhibited good rate performance (FIG. 4), and was at 0.3A g -1 Can provide 182 mAh g at 100 cycles of current density -1 Is 1A g in the reversible specific capacity (FIG. 5) -1 The reversible specific capacity of 300 times of circulation under the current density reaches 106 mAh g -1 While maintaining a high discharge voltage plateau of 1.6V (fig. 6-7), it is demonstrated that the potassium hydroxide-glycine alkaline mixed electrolyte can be shown to improve the cycling performance of aqueous alkaline zinc ion batteries.
Example 2
Completely dissolving potassium hydroxide solid in deionized water with the aid of ultrasonic wave, cooling to room temperature to obtain potassium hydroxide solution with concentration of 6 mol L -1 Adding glycine additive into the potassium hydroxide solution, stirring until the solution is clear and transparent, wherein the concentration ratio of potassium hydroxide to glycine is 6 mol L -1 :0.2 mol L -1 The aqueous potassium hydroxide-glycine alkaline mixed electrolyte is prepared.
In a three-electrode test system, the potassium hydroxide-glycine alkaline mixed electrolyte is introduced, ag/AgCl is used as a reference electrode, and zinc foil is used as a linear sweep voltammogram of a counter electrode and a working battery test electrolyte.
The potassium hydroxide-glycine alkaline mixed electrolyte is introduced, a zinc foil is used as an electrode, whatman GF/D is used as a diaphragm, and a Zn symmetric battery is assembled.
Introducing the potassium hydroxide-glycine alkaline mixed electrolyte, taking zinc foil as a negative electrode and Ni 0.8 Co 0.1 Mn 0.1 O 2 As the positive electrode material, whatman GF/D is assembled into Zn Ni for the diaphragm 0.8 Co 0.1 Mn 0.1 O 2 Full cell (CR 2025 type).
Example 3
Completely dissolving sodium hydroxide solid in deionized water with the aid of ultrasonic wave, cooling to room temperature to obtain sodium hydroxide solution with concentration of 1 mol L -1 Adding glycine additive into the sodium hydroxide solution, stirring until the solution is clear and transparent, wherein the concentration ratio of sodium hydroxide to glycine is 1 mol L -1 :0.02 mol L -1 The aqueous potassium hydroxide-glycine alkaline mixed electrolyte is prepared.
In a three-electrode test system, the sodium hydroxide-glycine alkaline mixed electrolyte is introduced, ag/AgCl is used as a reference electrode, and zinc foil is used as a linear sweep voltammogram of a counter electrode and a working battery test electrolyte.
The sodium hydroxide-glycine alkaline mixed electrolyte is introduced, a zinc foil is used as an electrode, whatman GF/D is used as a diaphragm, and a Zn symmetric battery is assembled.
Introducing the sodium hydroxide-glycine alkaline mixed electrolyte, taking zinc foil as a negative electrode and Ni 0.8 Co 0.1 Mn 0.1 O 2 As the positive electrode material, whatman GF/D is assembled into Zn Ni for the diaphragm 0.8 Co 0.1 Mn 0.1 O 2 Full cell (CR 2025 type).
Example 4
Completely dissolving lithium hydroxide solid in deionized water under the assistance of ultrasonic waves, and cooling to room temperature to obtain a lithium hydroxide solution with the concentration of 3 mol L -1 Adding glycine additive into the lithium hydroxide solution, stirring until the solution is clear and transparent, wherein the concentration ratio of the lithium hydroxide to the glycine is 3 mol L -1 :0.5 mol L -1 The aqueous potassium hydroxide-glycine alkaline mixed electrolyte is prepared.
In a three-electrode test system, the lithium hydroxide-glycine alkaline mixed electrolyte is introduced, ag/AgCl is used as a reference electrode, and zinc foil is used as a linear sweep voltammogram of a counter electrode and a working battery test electrolyte.
The lithium hydroxide-glycine alkaline mixed electrolyte is introduced, a zinc foil is used as an electrode, whatman GF/D is used as a diaphragm, and a Zn symmetric battery is assembled.
The lithium hydroxide-glycine alkaline mixed electrolyte is introduced, zinc foil is taken as a negative electrode, ni 0.8 Co 0.1 Mn 0.1 O 2 As the positive electrode material, whatman GF/D is assembled into Zn Ni for the diaphragm 0.8 Co 0.1 Mn 0.1 O 2 Full cell (CR 2025 type).
The foregoing description is only of the preferred embodiments of the invention, and all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.