Zinc ion battery electrolyte containing sulfonated cellulose nanowhisker additive as well as preparation method and application of zinc ion battery electrolyte

Abstract

The invention discloses a zinc ion battery electrolyte containing a sulfonated cellulose nanowhisker additive as well as a preparation method and application of the zinc ion battery electrolyte, and belongs to the technical field of battery materials. The zinc ion battery electrolyte comprises zinc salt, water and an additive, wherein the additive is sulfonated cellulose nanowhiskers. The electrolyte provided by the invention adopts the sulfonated cellulose nanowhiskers as an additive, and a sulfonate group promotes a desolvation process of hydrated Zn < 2 + >, reduces the activity of free water, inhibits generation of hydrogen evolution reaction byproducts and effectively inhibits growth of zinc dendrites by changing a solvation structure of zinc ions and inhibiting strong interaction between water molecules and Zn < 2 + >. The self-discharge of the battery is inhibited, the corrosion current is reduced, the corrosion potential is improved, the cycle stability of the battery is improved, and the cycle life of the battery is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery materials, in particular to a zinc ion battery electrolyte containing sulfonated cellulose nanowhisker additive and a preparation method and application thereof. BACKGROUND

[0002] With the development of electronic equipment and electrification, people have higher requirements for energy storage equipment. As an important part of new energy technology, lithium ion battery technology occupies a dominant position in the energy storage market, but faces multiple challenges such as environmental pollution, safety hazards, and high costs. Water-based zinc ion batteries have attracted widespread attention and research in large-scale energy storage due to the inherent safety of water-based electrolytes, high theoretical capacity of anodes, suitable redox potential, and low cost. Unfortunately, water-based zinc ion batteries face many challenges in zinc anodes and various cathodes. On the one hand, zinc anodes are prone to dendrite formation, corrosion, and hydrogen evolution. To solve these problems, people have explored various strategies, including zinc anode modification, electrolyte additives, hydrogel electrolytes, and separator engineering. However, many of these methods have trade-offs, such as increased cost, environmental impact, or increased manufacturing complexity. In addition, most research to date has focused on laboratory button cells, which do not fully reflect the challenges faced when scaling up to larger-scale soft-pack batteries and other larger scales. Scaling up presents additional difficulties, such as ensuring uniform zinc ion transport and inhibiting dendrite growth, which are crucial for the successful application of large zinc batteries in the energy storage field.

[0003] A promising solution lies in the use of electrolyte additives, which can promote uniform zinc ion deposition and inhibit zinc dendrite growth through ions or groups in the electrolyte. Cellulose nanomaterials have shown great potential in the development of high-performance separators for water-based batteries due to their high aspect ratio, excellent hydrophilicity, and renewability, as well as low carbon emissions throughout the life cycle, making them green and economical. The abundant hydroxyl groups in cellulose fibers not only facilitate the effective penetration of electrolytes but also enhance the mechanical properties of cellulose fibers through van der Waals forces. For example, Chinese Patent CN116826194A discloses a high-performance zinc-based water-based electrolyte and its application. The electrolyte of the invention includes water, zinc salt, and cellulose nanocrystals. The zinc-based water-based electrolyte of the invention has the characteristics of non-toxicity, environmental protection, high safety, and low additive cost. When used in batteries and capacitors, it can promote uniform zinc deposition, inhibit zinc dendrite growth, and hinder the occurrence of side reactions, greatly improving the charge and discharge efficiency and cycle stability of batteries and capacitors. However, cellulose nanocrystals in the electrolyte are prone to agglomeration and sedimentation due to hydrogen bonding and van der Waals forces, which can lead to uneven distribution, blockage of electrode or separator pores, low effective additive amount, and instability. In addition, the hydroxyl groups in cellulose nanocrystals are prone to hydrolytic degradation under weak acidic conditions, and the function of the additive will decline over time, affecting the cycle life and stability.

[0004] At present, zinc ion battery still has the problems of zinc dendrite growth and hydrogen evolution reaction, which affects the cycle stability and battery life. SUMMARY

[0005] In view of the deficiencies in the prior art, one of the purposes of the present application is to provide a zinc ion battery electrolyte containing sulfonated cellulose nanowhisker additive. The electrolyte of the present application can effectively inhibit the generation of hydrogen evolution reaction byproducts and inhibit the growth of zinc dendrites, significantly improve the cycle stability of the battery, prolong the cycle life of the battery, and can be compatible with lead-acid battery production lines and adapt to 48V communication base stations.

[0006] The purpose of the present application is achieved by the following technical solutions.

[0007] A zinc ion battery electrolyte containing sulfonated cellulose nanowhisker additive, the zinc ion battery electrolyte comprising zinc salt, water and additive, the additive being sulfonated cellulose nanowhisker.

[0008] In the electrolyte of the present application, sulfonated cellulose nanowhisker is used as an additive. The sulfonic acid group (-SO3 - ) on the surface of the sulfonated cellulose nanowhisker will have a strong interaction with Zn 2+ , which can promote the desolvation process of hydrated Zn 2+ , reduce the direct contact of hydrated zinc ions, and reduce the hydrogen evolution reaction. In addition, the sulfonic acid group is a hydrophilic group, which can ensure the dispersibility and interfacial adsorption capacity of the sulfonated cellulose nanowhisker in the aqueous solution, and provide support for the interaction of -SO3 - and Zn 2+ ; at the same time, the dissociation of the sulfonic acid group provides more H + , balances the charge and accelerates ion migration, which helps to inhibit the growth of zinc dendrites, thereby improving the cycle life of the battery, enhancing the cycle stability of the battery, achieving high ionic conductivity, low polarization and long cycle life.

[0009] In addition, in view of the problem that cellulose nanocrystals are easy to agglomerate and settle in the electrolyte, which will lead to uneven distribution, blockage of electrode or separator pores, and degradation of the function of the additive in long-term cycle, affecting the cycle life and stability, the present application uses sulfonated cellulose nanowhisker to realize stable and uniform dispersion by strong electrostatic repulsion, and the sulfonic acid group is more resistant to acid hydrolysis, so that the chemical stability is greatly improved, and the battery cycle life is longer.

[0010] Preferably, the mass ratio of the zinc salt to the sulfonated cellulose nanowhisker is (100-200):1. More preferably, the mass ratio of the zinc salt to the sulfonated cellulose nanowhisker is 143:1.

[0011] Preferably, the zinc salt includes at least one of zinc sulfate, zinc trifluoromethanesulfonate, zinc nitrate, zinc chloride, and zinc acetate.

[0012] Preferably, the concentration of the zinc salt in the zinc-ion battery electrolyte is 1~3 mol / L.

[0013] Preferably, the diameter of the sulfonated cellulose nanocrystals is 4~10nm and the length is 100~500nm.

[0014] Another object of the present invention is to provide a method for preparing the zinc-ion battery electrolyte containing the sulfonated cellulose nanofiber additive, comprising the following steps: dissolving the zinc salt in water, then adding the sulfonated cellulose nanofiber, stirring evenly, thereby obtaining the zinc-ion battery electrolyte containing the sulfonated cellulose nanofiber additive.

[0015] Preferably, the stirring speed is 300~500 r / min and the stirring time is 0.5~2 h.

[0016] Another object of the present invention is to provide the application of the zinc-ion battery electrolyte containing the sulfonated cellulose nanofiber additive in zinc batteries.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] (1) The electrolyte of the present invention uses sulfonated cellulose nanofibers as an additive. The sulfonate groups inhibit the reaction of water molecules with Zn by changing the solvation structure of zinc ions. 2+ The strong interaction between them promotes the hydration of Zn. 2+ The desolvation process reduces the activity of free water, inhibits the formation of hydrogen evolution reaction byproducts, and effectively suppresses zinc dendrite growth.

[0019] (2) Compared with cellulose nanocrystals, using sulfonated cellulose nanocrystal whiskers as an electrolyte additive can significantly improve the initial specific capacity and cycle stability of the battery, and the battery exhibits superior electrochemical performance.

[0020] (3) The electrolyte of the present invention can effectively inhibit the growth of zinc dendrites, inhibit battery self-discharge, reduce corrosion current, increase corrosion potential, improve battery cycle stability, extend battery cycle life, and is compatible with lead-acid battery production lines and 48V communication base stations.

[0021] (4) The zinc-ion battery electrolyte preparation method of the present invention is simple and environmentally friendly, and can be obtained by a simple dissolution method. Attached Figure Description

[0022] Figure 1A physical comparison chart of the CNC, CNC-E, S-CNC, S-CNC-E and ZnSO4 solution provided by the present application;

[0023] Figure 2 A Fourier infrared spectrum and a Raman spectrum of the CNC, CNC-E, S-CNC, S-CNC-E provided by the present application;

[0024] Figure 3 A cycle test chart and a charge-discharge curve chart of the Zn / / Zn symmetric battery;

[0025] Figure 4 A coulombic efficiency chart and a charge-discharge curve chart of the Zn / / Cu half-cell;

[0026] Figure 5 A cycle performance chart, a charge-discharge curve and a CV cycle chart of the NH4VO3 / / Zn full cell;

[0027] Figure 6 A picture of three full cells connected in series to light up an LED lamp;

[0028] Figure 7 A voltage test chart of three full cells connected in series. DETAILED DESCRIPTION

[0029] The applicant will make further detailed description of the method of the present application in combination with specific examples, and the purpose is to enable the person skilled in the art to clearly understand the present application. However, the following examples should not be understood as limiting the scope of protection claimed by the present application in any degree.

[0030] The zinc ion battery electrolyte containing sulfonated cellulose nanowhisker additive of the present application comprises a zinc salt, water and an additive, and the additive is sulfonated cellulose nanowhisker.

[0031] In the zinc ion battery electrolyte of the present application, the concentration of the zinc salt is 1-3 mol / L, and the mass ratio of the zinc salt to sulfonated cellulose nanowhisker is (100-200):1.

[0032] In the present application, the zinc salt can be selected from at least one of zinc sulfate, zinc trifluoromethane sulfonate, zinc nitrate, zinc chloride and zinc acetate.

[0033] In the present application, the sulfonated cellulose nanowhiskers can be added in the form of a dispersion liquid or in the form of a dry powder. For example, in the following examples, the sulfonated cellulose nanowhiskers are added in the form of a dispersion liquid, and the sulfonated cellulose nanowhisker dispersion liquid has a content of 4.0 wt%, a diameter of 4-10 nm, a length of 100-500 nm, and a pH of 4.0.

[0034] Example 1

[0035] The method for preparing the zinc ion battery electrolyte containing the sulfonated cellulose nanowhisker additive of the present embodiment includes the following steps:

[0036] 17.24 g of zinc sulfate heptahydrate was weighed and dissolved in 30 mL of water to obtain a 2 mol / L ZnSO4 solution, and then 3 mL of a sulfonated cellulose nanowhisker (S-CNC) dispersion liquid was added. The mixture was stirred with a magnetic stirrer for 30 min at a speed of 400 r / min to obtain a mixed solution of zinc sulfate and sulfonated cellulose nanowhiskers (hereinafter referred to as S-CNC-E, and the mass ratio of zinc sulfate to sulfonated cellulose nanowhiskers in S-CNC-E is 143:1), i.e., the S-CNC-E electrolyte solution.

[0037] Comparative Example 1

[0038] The present comparative example is basically the same as Example 1, except that the S-CNC dispersion liquid is replaced by a cellulose nanocrystal (CNC) dispersion liquid to obtain a mixed solution of zinc sulfate and cellulose nanocrystals (hereinafter referred to as CNC-E), i.e., the CNC-E electrolyte solution.

[0039] Figure 1 The CNC dispersion liquid used in Comparative Example 1 and the obtained CNC-E, the S-CNC dispersion liquid used in Example 1 and the obtained S-CNC-E, and the zinc sulfate solution are compared in the following figure. As can be seen from the figure, the CNC is in a light yellow and slightly turbid state, the CNC-E is in a transparent and turbid state, the S-CNC is in a milky white state, the S-CNC-E is in a milky white and slightly transparent state, and the ZnSO4 is completely clear.

[0040] The original aqueous solutions S-CNC, CNC, S-CNC-E prepared in Example 1, and CNC-E prepared in Comparative Example 1 were subjected to Fourier infrared spectroscopy and Raman spectroscopy tests, and the results are shown in Figure 2 Figure 2 a and Figure 2 b show the absorption peaks of S-CNC and S-CNC-E corresponding to several functional groups, 1640 cm -1 ​The peak at 3320 cm -1 is formed by C=O bond stretching vibration, and the new peak at 1100 cm -1 is formed by O-H bond stretching vibration, and the new peak at 1100 cm 2+ is formed by the coordination vibration of O-Zn bond caused by the coordination of Zn -1 with hydroxyl groups, resulting in a new peak at 1100 cm 2+ . The peak enhancement helps to build a directional ion channel, allowing Zn 2- to be uniformly deposited, thus eliminating local concentration gradients of the electrode, preventing dendrite nucleation from the source. SO4 2+ has a negative charge and participates in the formation of an electric double layer at the electrode / electrolyte interface, which can form a coordination with Zn 2+ through electrostatic attraction, to some extent, delaying the rapid reduction of Zn 2+ , avoiding excessive local Zn - concentration, thereby inhibiting the uneven deposition of zinc on the electrode surface, while the -SO3 -1 in the sulfonated cellulose nanowhisker can adsorb a small amount of water, reducing the direct contact of zinc ions with water, reducing the occurrence of hydrogen evolution side reactions, regulating the solvation structure of ions, further optimizing the properties of the electrolyte, and enhancing the stability of the electrolyte system.

[0041] Further, Figure 2 c and Figure 2 d show the absorption peaks of CNC and CNC-E corresponding to several functional groups, 3400 cm -1 is formed by O-H bond stretching vibration, and the CNC-E peak is broadened, indicating that the free hydroxyl group is converted to a stable hydrogen bond structure, enhancing the hydrogen bond. Strong hydrogen bonding can reduce the activity of free water molecules, reduce water decomposition-induced corrosion and electrode corrosion, and reduce free hydroxyl groups through crosslinking to inhibit side reactions and improve electrolyte stability. Although it has improved compared to ordinary ZnSO4 solution, it can increase the surface area and active sites, and improve the initial kinetics, but the lack of interface protection leads to decay later. The -SO3 - on the surface of the sulfonated cellulose nanowhisker can have a strong interaction with Zn 2+ , which can promote the desolvation process of hydrated zinc ions. The surface of the cellulose nanowhisker is mainly hydroxyl, which has a relatively weak interaction with Zn 2+ , has a smaller effect on the solvation structure of zinc ions, and lacks the special role of -SO3 - in inhibiting side reactions and maintaining interface stability. In summary, the comprehensive performance of CNC-E is inferior to that of S-CNC-E electrolyte.

[0042] Example 2

[0043] The preparation method of the zinc ion battery electrolyte containing the sulfonated cellulose nanowhisker additive of the embodiment comprises the following steps:

[0044] 8.63 g of zinc sulfate heptahydrate was weighed into 30 mL of water to dissolve it to obtain a 1 mol / L ZnSO4 solution, then 2.16 mL of sulfonated cellulose nanowhisker (S-CNC) dispersion liquid was added, and stirred with a magnetic stirrer for 60 min at a speed of 500 r / min, to obtain a mixed solution of zinc sulfate and sulfonated nanocellulose whiskers (hereinafter referred to as S-CNC-E, the mass ratio of zinc sulfate to sulfonated cellulose nanowhisker in S-CNC-E is 100:1), which is the S-CNC-E electrolyte solution.

[0045] Example 3

[0046] The preparation method of the zinc ion battery electrolyte containing the sulfonated cellulose nanowhisker additive of the embodiment comprises the following steps:

[0047] 25.88 g of zinc sulfate heptahydrate was weighed into 30 mL of water to dissolve it to obtain a 3 mol / L ZnSO4 solution, then 3.24 mL of sulfonated cellulose nanowhisker (S-CNC) dispersion liquid was added, and stirred with a magnetic stirrer for 120 min at a speed of 300 r / min, to obtain a mixed solution of zinc sulfate and sulfonated nanocellulose whiskers (hereinafter referred to as S-CNC-E, the mass ratio of zinc sulfate to sulfonated cellulose nanowhisker in S-CNC-E is 200:1), which is the S-CNC-E electrolyte solution.

[0048] Application Example

[0049] ①Material preparation

[0050] Preparation of NH4VO3 / / Zn full battery positive electrode sheet: the positive electrode active material ammonium vanadate, the conductive agent acetylene black, and the binder polyvinylidene fluoride were mixed in a mass ratio of 7:2:1 to form a uniform positive electrode slurry, which was coated on a carbon paper substrate, dried, and then the positive electrode sheet was punched to a diameter of 12 mm.

[0051] The zinc sheet and copper sheet with a diameter of 12 mm, the zinc sheet with a diameter of 15 mm, and the separator with a diameter of 16 mm were prepared using a sheet punching machine.

[0052] ②Assemble the battery

[0053] The negative shell, zinc sheet, separator, electrolyte, zinc sheet, gasket, spring, and positive shell were assembled in sequence, the battery was put into the device and compressed, and a main sample battery of a Zn / / Zn symmetric battery using S-CNC-E as the electrolyte and a comparative sample battery of a Zn / / Zn symmetric battery using CNC-E as the electrolyte were obtained. Then, according to the above method, a Zn / / Cu half-cell using S-CNC-E and CNC-E as the electrolyte was prepared by using a 12 mm copper sheet as the positive electrode; then, a NH4VO3 / / Zn full cell using S-CNC-E and CNC-E as the electrolyte was prepared by using the positive electrode sheet with a diameter of 12 mm prepared in step 1 as the positive electrode.

[0054] ③Zn / / Zn symmetric battery test

[0055] The Zn / / Zn symmetric battery assembled in step 2 was placed on a blue electric test system for testing, and constant current charge-discharge was performed under the condition of a current density of 5 mA·cm-2 and a specific capacity of 1 mAh·cm-3. -2 -2 The test results are shown in Table 1. Figure 3 Figure 3 It can be seen from Table 1 that, under the same test conditions, the polarization voltage using S-CNC as the electrolyte additive is smaller than that using ZnSO4 solution alone, and the cycle is more stable. Figure 3 Figure 3 It can be seen from Table 1 that, compared with using ZnSO4 solution and using CNC as the additive, the polarization voltage is smaller when using S-CNC as the additive, and the stable overpotential is always maintained at 50 mV, which shows stable cycle performance, and the advantages of inhibiting the growth of zinc dendrites, reducing the polarization voltage, and reducing the nucleation overpotential can be obviously seen.

[0056] ④Zn / / Cu half-cell test

[0057] The Zn / / Cu half-cell assembled in step 2 was placed on a blue electric test system for testing, and constant current charge-discharge was performed under the condition of a current density of 5 mA·cm-2 and a specific capacity of 1 mAh·cm-3. -2 -2 The test results are shown in Table 2. Figure 4 It can be seen from Table 2 that, when S-CNC is used as the additive, the coulombic efficiency is stable at about 100%, and the cycle life is longer.

[0058] Figure 4 Further, from Table 2, it can be seen that, compared with using ZnSO4 solution and using CNC as the additive, the polarization voltage is smaller when using S-CNC as the additive, and the stable overpotential is always maintained at 50 mV, which shows stable cycle performance, and the advantages of inhibiting the growth of zinc dendrites, reducing the polarization voltage, and reducing the nucleation overpotential can be obviously seen. Figure 4 ​​​​​cIt can be seen that the polarization voltage is smaller when S-CNC is used as an additive, which reduces the polarization voltage. Its lower polarization voltage proves that the solution is superior to CNC-E system in reducing the interface reaction resistance and improving the energy efficiency. The sulfonation treatment significantly improves the interface compatibility of the nanocrystalline electrode, indicating that the battery using S-CNC-E as electrolyte has less dendrite on the surface, and exhibits better and more stable cycle performance.

[0059] ⑤NH4VO3 / / Zn full battery test

[0060] The NH4VO3 / / Zn full battery assembled in step ② was placed on a blue light test system for testing. Under the conditions of a current density of 5A•g -1 , a charge / discharge interval of 0.4-1.8V, constant current charging and discharging were carried out. As shown in Figure 5 a, the results show that the initial specific capacity of the battery using S-CNC-E as electrolyte is significantly better than that of CNC-E.

[0061] Further, we tested the charge / discharge curves of the full batteries using S-CNC-E and CNC-E as electrolyte, and the results are shown in Figure 5 b, Figure 5 c. The results show that the curve using S-CNC-E as electrolyte maintains a clear charge / discharge platform at different cycle numbers, and the platform decays slowly with the increase of cycle number, and the polarization voltage is small; while the curve using CNC-E as electrolyte, the polarization is significantly intensified with the increase of cycle number.

[0062] Further, we tested the CV of the full batteries using S-CNC-E and CNC-E as electrolyte, setting the scanning rate from 1 to 10 mV / s, and taking several cycles, and the results are shown in Figure 5 d and Figure 5 e. The curve using S-CNC-E as electrolyte changes more gently with the increase of scanning rate, the curve symmetry is high, the oxidation / reduction peak position is stable, the peak separation degree is small, indicating that the charge transfer is faster and the internal resistance is lower, the capacity is better maintained at high scanning rate, indicating that its structure is more conducive to ion transmission; indicating that zinc ion migration is fast, interface reaction is reversible, and battery self-discharge can be inhibited, corrosion current is reduced and corrosion potential is improved. The reduction peak of the curve using CNC-E as electrolyte gradually moves negatively, indicating that the zinc deposition energy barrier increases, the peak shape is wide and asymmetric, reflecting the interface inhomogeneity and slow ion diffusion.

[0063] Further, we connected three full batteries assembled using S-CNC-E and CNC-E as additives in series, and measured their voltage after charging and whether they could light up LED lights, and the results are shown in Figure 6 and Figure 7As shown, the results show that the charging and discharging can be normally performed, and the LED lamp can be normally lighted.

[0064] In summary, the above results all show that the S-CNC-E solution can significantly improve the cycle performance of the battery by regulating the zinc ion deposition behavior, stabilizing the electrode interface and optimizing the electrochemical reaction kinetics.

[0065] While embodiments of the application have been shown and described, it is to be understood that the application is not limited to these embodiments. Rather, it is the intention that modifications, changes, substitutions and alterations be made in the application without departing from the spirit and scope of the application, which is defined solely by the claims and their equivalents.

Claims

1. A zinc-ion battery electrolyte containing sulfonated cellulose nanofibers as an additive, characterized in that, The zinc-ion battery electrolyte includes zinc salt, water, and additives, wherein the additives are sulfonated cellulose nanofibers.

2. The zinc-ion battery electrolyte containing sulfonated cellulose nanofibers as an additive according to claim 1, characterized in that, The mass ratio of the zinc salt to the sulfonated cellulose nanocrystals is (100~200):

1.

3. The zinc-ion battery electrolyte containing sulfonated cellulose nanofibers as an additive according to claim 2, characterized in that, The mass ratio of the zinc salt to the sulfonated cellulose nanocrystals is 143:

1.

4. The zinc-ion battery electrolyte containing sulfonated cellulose nanofibers as an additive according to claim 1, characterized in that, The zinc salt includes at least one of zinc sulfate, zinc trifluoromethanesulfonate, zinc nitrate, zinc chloride, and zinc acetate.

5. The zinc-ion battery electrolyte containing sulfonated cellulose nanofibers as an additive according to claim 1, characterized in that, In the zinc-ion battery electrolyte, the concentration of the zinc salt is 1~3 mol / L.

6. The zinc-ion battery electrolyte containing sulfonated cellulose nanofibers as an additive according to claim 1, characterized in that, The diameter of sulfonated cellulose nanocrystals is 4~10nm and the length is 100~500nm.

7. A method for preparing the zinc-ion battery electrolyte containing sulfonated cellulose nanofiber additive as described in any one of claims 1 to 6, characterized in that, The process includes the following steps: dissolving the zinc salt in water, then adding the sulfonated cellulose nanocrystals, and stirring until homogeneous to obtain the zinc-ion battery electrolyte containing the sulfonated cellulose nanocrystal additive.

8. The preparation method according to claim 7, characterized in that, The stirring speed is 300~500 r / min, and the stirring time is 0.5~2 h.

9. The application of the zinc-ion battery electrolyte containing sulfonated cellulose nanofiber additive as described in any one of claims 1 to 6 in a zinc battery.

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