Aqueous zinc ion battery electrolyte additive, electrolyte and application thereof

Abstract

The application belongs to the technical field of aqueous zinc ion batteries, and specifically discloses an aqueous zinc ion battery electrolyte additive, an electrolyte and application thereof. The application provides application of a compound as shown in structure (I) as an electrolyte additive in an aqueous zinc ion battery, wherein R + represents one or more of H + , Na + and K + . The compound as an electrolyte additive in the aqueous zinc ion battery can improve the interface environment between the electrolyte and the zinc negative electrode, promote uniform distribution of an electric field and a zinc ion concentration field, reduce nucleation potential, and make the zinc deposition process more uniform. The compound can effectively solve the problems of zinc dendrite growth, zinc negative electrode corrosion and surface passivation, effectively reduce the consumption of the electrolyte, improve the utilization rate of zinc, and thus improve the rate performance and cycle performance of the aqueous zinc ion battery.

Description

Technical Field

[0001] This invention belongs to the technical field of aqueous zinc-ion batteries, specifically relating to an electrolyte additive, electrolyte, and its application in aqueous zinc-ion batteries. Background Technology

[0002] Modern society's demand for electricity is constantly increasing. Inexpensive, reliable, and eco-friendly energy storage (EES) will play a crucial role in meeting this demand. An ideal EES device should possess high capacity, fast charging and discharging, safety, environmental friendliness, and low cost. Among existing EES technologies, rechargeable metal batteries show promise in terms of energy density, scalability, and flexibility. Zinc-based electrodes using zinc as the negative electrode mainly include zinc-air batteries and zinc-based flow batteries, which have been extensively studied due to their versatility. Zinc has a relatively high specific capacity (820 mAh g / g). -1 It is low-cost, safe to operate, and relatively non-toxic compared to other metal anodes (such as lithium and sodium). Furthermore, compared to the potential of a standard hydrogen electrode, Zn / Zn... 2+ Zinc has an oxidation potential of -0.763V (vs. SHE), making it suitable for use as a metal anode in aqueous electrolytes. Therefore, batteries using zinc anodes are easy to manufacture and have a smaller environmental and economic impact. These advantages make aqueous zinc-ion batteries significant for global energy development.

[0003] While the mild aqueous electrolyte makes zinc-ion batteries inherently safer than widely used lithium-ion batteries, it also presents the problem of uneven and uncontrollable zinc ion deposition / dissolution kinetics. This leads to uneven potential distribution on the zinc anode side, easily causing a tipping effect and resulting in the formation and growth of zinc dendrites. Simultaneously, the presence of a large amount of free-flowing water in the electrolyte causes electrochemical side reactions and uncontrollable solid-liquid interface reactions at the zinc anode, leading to surface passivation and significantly increasing the risk of corrosion. These zinc anode problems result in excessively rapid capacity decay and reduced coulombic efficiency in aqueous zinc-ion batteries during charge and discharge, affecting rate performance and cycle performance. More seriously, excessive zinc dendrite growth can puncture the separator, causing short circuits and creating safety hazards. All of these factors severely restrict the further development and commercial application of aqueous zinc-ion batteries.

[0004] Suppressing dendrite growth and side reactions, as well as controlling and adjusting the solvation structure, are important solutions for improving the reversibility of zinc anodes. Current specific measures mainly include the development of solid gel electrolytes, structural design and surface modification of zinc anodes, and the use of electrolyte additives. The development of solid gel electrolytes primarily involves cross-linking with organic materials to construct gel electrolytes with stable ion channels and high mechanical strength, allowing for more uniform zinc ion deposition and thus reducing side reactions, effectively improving the coulombic efficiency of aqueous zinc-ion batteries. Zinc anode surface modification mainly involves coating a very thin layer of material to influence the solid-liquid interface reaction, blocking direct contact between the zinc anode and the electrolyte, and reducing the local exchange current density, thereby enabling uniform zinc ion deposition. However, due to the complexity and high cost of these measures, large-scale use is not yet feasible. Using high-concentration zinc-based electrolytes in zinc-ion batteries can bring good performance. By reducing the free water content in the electrolyte and disrupting the solvation sheath structure of zinc ions, corrosion reactions and zinc dendrite growth can be effectively reduced. However, the high cost of high-concentration zinc-based electrolytes negates the economic advantage of aqueous zinc-ion batteries. Therefore, the use of electrolyte additives is currently the most economical method. Suitable electrolyte additives can selectively adsorb at zinc deposition sites, inducing a uniform distribution of ion concentration and electric field near the zinc anode, thereby improving the interfacial environment between the zinc anode and the electrolyte, preventing excessive growth of zinc dendrites. Simultaneously, the addition of additives inhibits hydrogen evolution reaction, reducing zinc anode corrosion and surface passivation. However, traditional organic polymer electrolyte additives pose safety hazards such as flammability and toxicity, limiting their practical application in large-scale energy storage. Therefore, researchers are currently focusing their research on developing green and environmentally friendly aqueous zinc-ion battery electrolyte additives. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an electrolyte additive for aqueous zinc-ion batteries, an electrolyte thereof, and their applications. This electrolyte additive can effectively inhibit the growth of zinc dendrites, effectively solve problems such as zinc anode corrosion and surface passivation, and improve its rate performance and cycle performance. This is of great significance for improving the electrochemical performance, stability, and commercial application potential of aqueous zinc-ion batteries.

[0006] The primary objective of this invention is to provide an application of a compound as shown in structure (I) as an electrolyte additive in an aqueous zinc-ion battery, wherein R in the structural formula + The ion represented can be H. + Na + and K + One or more of them.

[0007]

[0008] Preferably, when the compound is used as an electrolyte additive, its mass accounts for 0.1%-10% of the total mass of the electrolyte. More preferably, the mass fraction is 0.1%.

[0009] A second objective of the present invention is to provide an aqueous zinc-ion battery electrolyte comprising a zinc salt or sodium salt, water, and a compound as shown in structure (I) above.

[0010] The mechanism of this invention is as follows: Applying DL-2,4-diaminopentanoic acid and its salts as electrolyte additives in aqueous zinc-ion batteries can effectively solve the problems of zinc dendrite formation, zinc anode corrosion, and surface passivation, thereby significantly improving the rate performance and cycle performance of the battery. DL-2,4-diaminopentanoic acid contains a large number of carboxyl and amino groups. Under the action of these functional groups, the amount of coordination water with zinc ions is reduced, keeping the electrolyte generally electrically neutral, lowering the nucleation potential during zinc deposition, and inducing a uniform distribution of ion concentration and electric field near the zinc anode. This allows deposition to preferentially occur on the (002) crystal plane, effectively regulating the uniform deposition and dissolution of zinc ions on the zinc anode surface and inhibiting the formation and growth of zinc dendrites. Furthermore, DL-2,4-diaminopentanoic acid and its salts also increase the activation energy of hydrogen adsorption on the zinc surface, reducing electrochemical side reactions and uncontrollable solid-liquid interface reactions on the zinc anode surface, thus effectively solving problems such as zinc anode corrosion and surface passivation.

[0011] Preferably, the zinc salt is one or more of zinc sulfate, zinc bromide, zinc nitrate, zinc chloride, and zinc trifluoromethanesulfonate, and the zinc salt concentration is 1M to 3M.

[0012] Preferably, the sodium salt includes one or more of sodium sulfate, sodium bromide, sodium nitrate, sodium chloride, and sodium trifluoromethanesulfonate, and the concentration of the sodium salt is 1M to 3M.

[0013] Preferably, the mass fraction of the compound is 0.1%-10%, more preferably 0.1%.

[0014] The present invention also provides an aqueous zinc-ion battery, comprising a positive electrode, a negative electrode, a separator, and the above-mentioned aqueous zinc-ion battery electrolyte.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] The electrolyte additive provided by this invention improves the interfacial environment between the electrolyte and the zinc anode, promoting uniform deposition and dissolution of zinc ions on the zinc anode surface. This effectively inhibits the formation and excessive growth of zinc dendrites. Furthermore, due to its unique functional groups, it reduces the activity of free water in the electrolyte, suppressing side reactions on the zinc anode surface and effectively mitigating zinc anode corrosion and surface passivation. Therefore, using the aqueous zinc-ion battery electrolyte additive provided by this invention can significantly improve the rate performance and cycle performance of aqueous zinc-ion batteries. In addition, the electrolyte additive provided by this invention is stable during use, contributing to the development of high-performance, safe, and stable aqueous zinc-ion batteries. Attached Figure Description

[0017] Figure 1 The long-cycle polarization curves of the Zn||Zn symmetric cells of the aqueous zinc-ion battery tested using the electrolyte of Example 1 and the reference electrolyte of Comparative Example 1 are shown.

[0018] Figure 2 The graph shows the long-cycle performance of an aqueous zinc-ion battery (Zn||V2O5) using the electrolyte of Example 1 and the reference electrolyte of Comparative Example 1.

[0019] Figure 3 The rate performance graph shows the performance of an aqueous zinc-ion battery using the electrolyte of Example 1 and the reference electrolyte of Comparative Example 1.

[0020] Figure 4 The time-voltage curves of aqueous zinc-ion batteries using the electrolyte of Example 1 and the reference electrolyte of Comparative Example 1 are presented.

[0021] Figure 5 The hydrogen evolution reaction overpotential curves of aqueous zinc-ion batteries using the electrolyte of Example 2 and the reference electrolyte of Comparative Example 2 are used to test the reaction.

[0022] Figure 6 The image shows a 3D graph (a) of the total composition distribution and fluorine distribution on the negative electrode surface of an aqueous zinc-ion battery using the reference electrolyte of Comparative Example 3.

[0023] Figure 7 The image shows a 3D graph (a) of the total composition distribution and fluorine distribution on the negative electrode surface of an aqueous zinc-ion battery using the electrolyte tested in Example 3. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods; unless otherwise specified, the materials and reagents used are commercially available.

[0026] Example 1

[0027] Preparation of the test electrolyte: Add DL-2,4-diaminopentanoic acid to a 2M zinc sulfate aqueous solution at a mass fraction of 0.1%, stir thoroughly until DL-2,4-diaminopentanoic acid (glu) is completely dissolved, and then let stand to obtain an aqueous zinc-ion battery electrolyte.

[0028] Assembling an aqueous zinc-ion battery based on the above electrolyte: The porous ZnO layer on the surface of metallic zinc significantly affects the battery's cycle stability. Using a 12mm diameter punch, zinc foil is punched into 12mm electrode sheets, pressed at 10MPa for 5 minutes, then polished with 2000-grit sandpaper, placed in an ethanol solution, sonicated for 5 minutes, and naturally dried in air to obtain the zinc negative electrode. Commercial Aladdin V2O5 powder is further reduced to prepare V2O5 positive electrode material. V2O5 powder, conductive carbon (Super P), and binder (PVDF) are mixed uniformly in a 7:2:1 ratio, added to NMP to prepare a slurry, and dripped onto carbon cloth and dried to obtain the positive electrode sheet. The battery is assembled in the following order: positive electrode shell, positive electrode sheet, separator, electrolyte, negative electrode sheet, gasket, spring sheet, and negative electrode shell. The battery is then compacted using a pressing machine to obtain the aqueous zinc-ion battery.

[0029] Example 2

[0030] Preparation of the test electrolyte: Add DL-2,4-diaminopentanoic acid (glu) to a 1M sodium sulfate aqueous solution at a mass fraction of 0.1%, stir thoroughly until DL-2,4-diaminopentanoic acid is completely dissolved, and then let stand to obtain an aqueous zinc-ion battery electrolyte.

[0031] Assembling an aqueous zinc-ion battery based on the above electrolyte: The porous ZnO layer on the surface of metallic zinc significantly affects the battery's cycle stability. Using a 12mm diameter punch, zinc foil is punched into 12mm electrode sheets, pressed at 10MPa for 5 minutes, then polished with 2000-grit sandpaper, placed in an ethanol solution, sonicated for 5 minutes, and naturally dried in air to obtain the zinc electrode. Commercial Aladdin V2O5 powder is further reduced to prepare V2O5 positive electrode material. V2O5 powder, conductive carbon (Super P), and binder (PVDF) are mixed uniformly in a 7:2:1 ratio, added to NMP to prepare a slurry, and dripped onto carbon cloth and dried to obtain the positive electrode sheet. The battery is assembled in the following order: positive electrode shell, positive electrode sheet, separator, electrolyte, negative electrode sheet, gasket, spring sheet, and negative electrode shell. The battery is then compacted using a pressing machine to obtain the aqueous zinc-ion battery.

[0032] Example 3

[0033] Preparation of the test electrolyte: Add DL-2,4-diaminopentanoic acid (glu) at a mass fraction of 0.1% to a 3M zinc trifluoromethanesulfonate aqueous solution, stir thoroughly until DL-2,4-diaminopentanoic acid is completely dissolved, and then let stand to obtain an aqueous zinc-ion battery electrolyte.

[0034] Assembling an aqueous zinc-ion battery based on the above electrolyte: The porous ZnO layer on the surface of metallic zinc significantly affects the battery's cycle stability. Using a 12mm diameter punch, zinc foil is punched into 12mm electrode sheets, pressed at 10MPa for 5 minutes, then polished with 2000-grit sandpaper, placed in an ethanol solution, sonicated for 5 minutes, and naturally dried in air to obtain the zinc electrode. Commercial Aladdin V2O5 powder is further reduced to prepare V2O5 positive electrode material. V2O5 powder, conductive carbon (Super P), and binder (PVDF) are mixed uniformly in a 7:2:1 ratio, added to NMP to prepare a slurry, and dripped onto carbon cloth and dried to obtain the positive electrode sheet. The battery is assembled in the following order: positive electrode shell, positive electrode sheet, separator, electrolyte, negative electrode sheet, gasket, spring sheet, and negative electrode shell. The battery is then compacted using a pressing machine to obtain the aqueous zinc-ion battery.

[0035] Comparative Example 1

[0036] Preparation of reference electrolyte and assembly of aqueous zinc-ion battery based thereon: (1) Prepare a 2M aqueous solution of zinc sulfate as an aqueous zinc-ion battery electrolyte. (2) Add sodium succinate (IUPAC) to the 2M zinc sulfate aqueous solution at a mass fraction of 0.1%, stir thoroughly until the sodium succinate is completely dissolved, and then let stand to obtain an aqueous zinc-ion battery electrolyte. (3) Add sodium glutamate (GluN) to the 2M zinc sulfate aqueous solution at a mass fraction of 0.1%, stir thoroughly until the sodium glutamate is completely dissolved, and then let stand to obtain an aqueous zinc-ion battery electrolyte.

[0037] The above three electrolytes were used as reference electrolytes. The positive and negative electrodes and assembly process of the aqueous zinc-ion battery using the reference electrolytes were the same as in Example 1.

[0038] Comparative Example 2

[0039] Preparation of reference electrolyte and assembly of aqueous zinc-ion battery based thereon: (1) Sodium sulfate was prepared into a 1M aqueous solution as an aqueous zinc-ion battery electrolyte. (2) Sodium succinate (IUPAC) was added to the 1M sodium sulfate aqueous solution at a mass fraction of 0.1%, and stirred thoroughly until the sodium succinate was completely dissolved. Then it was allowed to stand to obtain an aqueous zinc-ion battery electrolyte. (3) Sodium glutamate (Gluten) was added to the 1M sodium sulfate aqueous solution at a mass fraction of 0.1%, and stirred thoroughly until the sodium glutamate was completely dissolved. Then it was allowed to stand to obtain an aqueous zinc-ion battery electrolyte.

[0040] The above three electrolytes were used as reference electrolytes. The positive and negative electrodes and assembly process of the aqueous zinc-ion battery using the reference electrolytes were the same as in Example 2.

[0041] Comparative Example 3

[0042] Preparation of the reference electrolyte and assembly of an aqueous zinc-ion battery based on it: Zinc trifluoromethanesulfonate was prepared into a 3M aqueous solution as an aqueous zinc-ion battery electrolyte. Using the above electrolyte as a reference electrolyte, the positive and negative electrodes and assembly process of the aqueous zinc-ion battery using the reference electrolyte were the same as in Example 3.

[0043] Experimental Example Performance Testing and Analysis

[0044] Test methods

[0045] 1. Electrochemical performance test: The aqueous zinc-ion batteries of Example 1 and Comparative Example 1, which used the test electrolyte and the reference electrolyte respectively, were subjected to rate charge-discharge and constant current charge-discharge long cycle tests. The charge levels set for the rate were 1C, 2C, 3C, 5C and 10C, and the constant current density was set to 1.5A / g.

[0046] 2. The hydrogen evolution overpotential of the aqueous zinc-ion batteries prepared in Example 2 and Comparative Example 2 was studied using linear sweep voltammetry (LSV). The scan range was -1.7 to -1.4 V, and the scan rate was 1.0 mV / s. -1 .

[0047] 3. Material composition characterization: The composition of the negative electrode surface of the two aqueous zinc-ion batteries in Example 3 and Comparative Example 3 was characterized by time-of-flight secondary ion mass spectrometry (TOF-SIMS).

[0048] Results Analysis

[0049] Depend on Figure 1 The long-cycle polarization curves of the Zn||Zn symmetric cell show that at 0.5 mA cm⁻¹... -2 After cycling at a current density of 29 hours, the battery using 2M ZnSO4 electrolyte suddenly experienced a voltage spike. This was because uneven zinc ion deposition led to the continuous growth of zinc dendrites on the zinc anode surface, eventually piercing the separator and causing battery problems. Even the aqueous zinc-ion battery with 0.1% sodium glutamate added to the electrolyte experienced a voltage spike after 54 hours of cycling, indicating a problem with the battery. Conversely, the symmetric battery containing 0.1% DL-2,4-diaminopentanoic acid in the electrolyte exhibited a stable polarization potential over 440 hours, with electrochemical performance superior to the aqueous zinc-ion battery assembled using the reference electrolyte. This was attributed to the uniform zinc deposition on the zinc anode surface, resulting in a dendrite-free zinc anode. Furthermore, the addition of DL-2,4-diaminopentanoic acid improved the utilization rate of zinc in the electrolyte, enabling stable cycling at a higher zinc utilization rate.

[0050] Depend on Figure 2 The long-cycle performance graph of the Zn||V2O5 battery shows that at a current density of 2A g -1 The discharge capacities of the Zn||V2O5 battery at the 1st and 1500th cycles were 288.53 and 197.78 mAh g, respectively. -1 The corresponding capacity retention rate was 68.55%. After adding DL-2,4-diaminopentanoic acid to the electrolyte, the discharge capacities for the first and 1500th cycles were 310.56 and 276.65 mAh g, respectively. -1 The capacity retention rate after 1500 cycles was relatively high at 89.08%.

[0051] Depend on Figure 3The rate performance test results show that the aqueous zinc-ion battery using the test electrolyte has a significantly higher discharge specific capacity at 1C, 2C, 3C, 5C and 10C charge levels than the aqueous zinc-ion battery using the reference electrolyte, indicating that the battery using the test electrolyte prepared by the technical solution of this invention has excellent rate performance.

[0052] from Figure 4 The time-voltage curves show that the nucleation overpotential of the aqueous zinc-ion battery using the test electrolyte is significantly lower than that using the reference electrolyte, indicating that a lower nucleation overpotential is more conducive to zinc deposition. These results demonstrate that the test electrolyte can achieve full coverage of favorable nucleation sites, resulting in dendrite-free growth. Furthermore, with the addition of electrolyte additives, the Zn concentration in the solution... 2+ The reduced charge transfer impedance leads to an increased charge transfer rate and a significantly enhanced coulombic efficiency. Therefore, the aqueous zinc-ion battery using this test electrolyte exhibits excellent electrochemical performance.

[0053] from Figure 5 The overpotential curves of the hydrogen evolution reaction show that the hydrogen evolution overpotential in the Na2SO4 system containing 0.1% DL-2,4-diaminopentanoic acid is -1.680V (vs. SCE), the overpotential without additives is -1.602V, the overpotential with sodium succinate as an additive is -1.643V, and the overpotential with monosodium glutamate as an additive is -1.671V (based on the potential corresponding to a current of 4mA). Compared with the use of other additives, the hydrogen evolution overpotential shows a more significant negative shift after using DL-2,4-diaminopentanoic acid as an additive, indicating that the use of this electrolyte additive has a positive effect on inhibiting the hydrogen evolution reaction of the electrolyte, reducing electrochemical side reactions and uncontrollable solid-liquid interface reactions on the zinc anode surface, thereby effectively solving problems such as zinc anode corrosion and surface passivation.

[0054] from Figure 6 As shown in (a), the main component of the SEI film in an aqueous zinc-ion battery is ZnF2. Furthermore, as reflected in 6(b), the distribution of fluorine in the SEI film is not uniform, which may lead to increased local resistance. Figure 7 As shown in Figures (a) and (b), the addition of DL-2,4-diaminopentanoic acid promotes the uniform distribution of fluorine, making the SEI film of the battery more stable. A more stable SEI film means that the consumption of zinc ions in the solid-liquid contact phase will be reduced, allowing more zinc ions to participate in the charge transfer process, thus improving the utilization rate of zinc ions and further enhancing the coulombic efficiency and performance of the battery.

[0055] Therefore, DL-2,4-diaminopentanoic acid, as an organic compound, has good solubility. The addition of DL-2,4-diaminopentanoic acid lowers the nucleation potential during zinc deposition, effectively regulating the deposition orientation of zinc metal. The growth tendency of dendrites on the (101) crystal plane of the zinc surface is reduced, inducing zinc deposition preferentially on the (002) crystal plane, which is beneficial for smooth coating deposition and effectively inhibits the growth of zinc dendrites. When used as an electrolyte additive, DL-2,4-diaminopentanoic acid will autonomously occupy H₂O. + Adsorption becomes an active site for H*, increasing the activation energy for hydrogen formation and requiring more energy for the hydrogen evolution reaction, thus hindering corrosion. Simultaneously, DL-2,4-diaminopentanoic acid participates in the solvation coordination sheath of zinc ions and reduces the Zn concentration through the confinement function of the carboxylate group. 2+ The activity of surrounding water molecules achieves desolvation, while the amino groups maintain the overall electroneutrality of the electrolyte, thereby accelerating ion and charge transport. Furthermore, the addition of DL-2,4-diaminopentanoic acid reduces electrolyte consumption and improves zinc utilization, enabling stable cycling of the aqueous zinc-ion battery at a higher zinc utilization rate, thus enhancing its rate performance and cycle life.

[0056] Obviously, the specific implementation schemes described above are merely a further detailed explanation of the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above descriptions are only specific examples of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. Use of a compound as shown in structure (I) as an electrolyte additive in aqueous zinc ion batteries, characterized in that, The compound has general formula (I): wherein the formula R + represents one or more of H + , Na + and K + .

2. Use according to claim 1, characterized in that, The mass of the compound when used as an electrolyte additive is 0.1%-10% of the total mass of the electrolyte.

3. An aqueous zinc-ion battery electrolyte, characterized in that, The compound of claim 1, a zinc salt or a sodium salt, water, and water.

4. The aqueous zinc-ion battery electrolyte of claim 3, wherein, The zinc salt is one or more of zinc sulfate, zinc bromide, zinc nitrate, zinc chloride, and zinc triflate, and the concentration of the zinc salt is 1M-3M.

5. The aqueous zinc-ion battery electrolyte of claim 3, wherein, The sodium salt includes one or more of sodium sulfate, sodium bromide, sodium nitrate, sodium chloride, and sodium triflate, and the concentration of the sodium salt is 1M-3M.

6. The aqueous zinc-ion battery electrolyte of claim 3, wherein, The mass fraction of the compound is 0.1%-10%.

7. An aqueous zinc-ion battery, characterized in that, The compound of any one of claims 3-6, a positive electrode, a negative electrode, a separator, and an electrolyte.

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