Zinc-nickel battery electrolyte additive based on dynamic interface modification and preparation method thereof

Abstract

The application relates to the technical field of chemical energy and electric energy conversion, and particularly discloses a zinc-nickel battery electrolyte additive based on dynamic interface modification and a preparation method thereof. The additive is composed of an interface film former composed of sodium phytate and sodium dodecyl sulfonate, a cerium acetylacetone electric field regulator and a double-end amino polyethylene glycol bridging component in a specific mass ratio. Through the multiple synergistic mechanisms of interface film formation, electric field regulation and molecular bridging, the additive can construct an intelligent dynamic interface layer on the surface of a zinc negative electrode, and can synchronously and efficiently inhibit zinc dendrite growth and zinc self-corrosion. The microspherical additive prepared by using a high-speed shearing and spray drying process has good dispersibility and high stability. When the additive is applied to a zinc-nickel battery electrolyte, the cycle life, rate performance and high and low temperature performance of the battery can be remarkably improved, and the additive has important practical value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical energy and electric energy conversion, more particularly to a zinc-nickel battery electrolyte additive based on dynamic interface modification and a preparation method thereof. BACKGROUND

[0002] As a high-performance aqueous secondary battery, zinc-nickel battery has the advantages of high theoretical energy density, low cost and environmental friendliness, and shows broad application prospects in large-scale energy storage and power battery fields. However, the commercial application of zinc-nickel battery has been restricted by two key technical problems for a long time: zinc dendrite growth and zinc negative electrode self-corrosion.

[0003] During the battery cycle process, dendrites are easily formed on the surface of the zinc electrode, and the dendrites may pierce the separator when they grow to a certain extent, resulting in battery short circuit failure. At the same time, zinc is thermodynamically unstable in alkaline electrolyte, and will undergo hydrogen evolution corrosion reaction, resulting in battery capacity attenuation and cycle life shortening.

[0004] A variety of solutions have been proposed in the prior art. For example, some patents use inorganic additives such as borate and fluoride as electrolyte additives to form a barrier structure on the zinc negative electrode interface to inhibit side reactions. Another patent uses organic corrosion inhibitor such as hexadecyl trimethyl ammonium bromide to alleviate zinc corrosion. There are also studies that build a protective layer on the surface of zinc metal to improve corrosion resistance. However, these solutions often can only solve a single problem, or have the disadvantages of complex preparation process, high cost, limited effect, etc. For example, the interface film formed by inorganic additives lacks flexibility and cannot adapt to the volume change during zinc deposition / dissolution; a single organic corrosion inhibitor cannot effectively inhibit both dendrites and corrosion; and the surface modification layer increases the complexity and cost of electrode preparation.

[0005] Therefore, it is of great significance to develop an electrolyte additive that can simultaneously solve the problems of zinc dendrite growth and zinc self-corrosion, and has simple preparation and low cost, to promote the commercial application of zinc-nickel battery. SUMMARY

[0006] The purpose of the present application is to provide a zinc-nickel battery electrolyte additive based on dynamic interface modification and a preparation method thereof to solve the problems raised in the background.

[0007] To achieve the above purpose, on the one hand, the present application provides a zinc-nickel battery electrolyte additive based on dynamic interface modification, which comprises an interface film former, an electric field regulator and a bridging component, and the mass ratio of the interface film former, the electric field regulator and the bridging component is (1-5):(0.1-1):(0.5-2).

[0008] The interface film former is a composite of sodium phytate and sodium dodecyl sulfonate in a mass ratio of (2-5):1.

[0009] The electric field regulator is cerium acetylacetonate;

[0010] The bridging component is an amino-terminated polyethylene glycol.

[0011] Preferably, the mass ratio of the interfacial film former, the electric field regulator and the bridging component is (2-3):(0.2-0.5):(0.8-1.2).

[0012] Preferably, the amino-terminated polyethylene glycol has a molecular weight of 600-1000 and an amino content of no less than 0.8 mmol / g.

[0013] Preferably, the mass ratio of the sodium phytate and the sodium dodecyl sulfonate is 3:1.

[0014] Preferably, it further comprises nanocellulose whiskers accounting for 0.05%-0.2% of the total mass of the additive, and the length of the nanocellulose whiskers is 100-500 nm.

[0015] Preferably, the amino-terminated polyethylene glycol is a double-terminated amino-terminated polyethylene glycol.

[0016] In another aspect, the present application provides a preparation method of a zinc-nickel battery electrolyte additive based on dynamic interfacial modification, comprising the following steps:

[0017] The bridging component is heated to 60-80℃ to be molten to obtain liquid A;

[0018] The interfacial film former is dispersed in deionized water to form homogeneous slurry B;

[0019] The electric field regulator is dissolved in an organic solvent to form solution C;

[0020] Under high-speed shearing, slurry B and solution C are alternately added to liquid A, and reacted at 65-75℃ for 1-2h;

[0021] After the reaction, spray drying is performed to obtain a microspherical composite electrolyte additive.

[0022] Preferably, the rotation speed of the high-speed shearing is 8000-12000 rpm, and the frequency of the alternate addition is 1 switch every 30s, and the total volume of the corresponding slurry is 5%-10% for each alternate drop.

[0023] Preferably, the inlet temperature of the spray drying is 150-180℃, and the outlet temperature is 70-90℃.

[0024] Preferably, after the spray drying, the obtained microspheres are aged in an environment with a relative humidity of 50%-70% for 12-24h.

[0025] The mechanism of the present application is as follows:

[0026] The present application builds an intelligent and stable dynamic interface protection layer on the surface of zinc negative electrode through multiple synergistic effects among the components. The core mechanism is that: the two-end amino polyethylene glycol as the key "molecular bridge", the amino group at one end is firmly anchored on the surface of zinc negative electrode by coordination bond, and the amino group at the other end simultaneously interacts with the interface film-forming agent (the phosphate of sodium phytate and the sulfonate of sodium dodecyl sulfonate) and the electric field regulator (cerium acetylacetone and its reduced product) through hydrogen bond or coordination bond, thereby "weaving" a three-dimensional network-like composite interface layer. In this structure, sodium phytate forms a dense base barrier through multi-site strong coordination, effectively inhibiting zinc corrosion and side reactions; the hydrophobic long chain of sodium dodecyl sulfonate enhances the barrier to water molecules; and cerium acetylacetone preferentially adsorbs on the dendrite tip during electrochemical cycling, flattens the local electric field through its variable valence property, and induces the underpotential deposition of cerium, guiding zinc to nucleate uniformly, thereby eliminating the driving force for dendrite growth from the root. Ultimately, this "interface film-forming-electric field regulating" dual-mode synergistic system integrated by the "molecular bridge" achieves accurate regulation of the thermodynamics and kinetics of zinc deposition behavior, and long-term stability of the electrode / electrolyte interface, simultaneously solving the two technical problems of zinc dendrite growth and zinc self-corrosion.

[0027] The present application has the following beneficial effects:

[0028] (1) Multiple synergistic protection mechanism: The present application establishes a multiple synergistic protection mechanism through the ternary complex of interface film-forming agent, electric field regulator and bridging component. Sodium phytate and sodium dodecyl sulfonate form a dense interface film to inhibit corrosion reactions; cerium acetylacetone inhibits dendrite growth through electric field regulation effect; and two-end amino polyethylene glycol as a molecular bridge connects the functional components to form a stable three-dimensional network structure.

[0029] (2) Long-term protection ability: Unlike the problem of easy consumption and failure of traditional additives during cycling, the composite additive of the present application can form a stable interface protection layer and provide long-term protection. Experiments show that even after 500 cycles, the additive can still effectively function.

[0030] (3) Significant improvement in interface stability: Through the bridging action of two-end amino polyethylene glycol, the components are tightly combined on the surface of zinc electrode to form a more stable and dense protection layer, effectively blocking the direct contact of water molecules with the zinc electrode and greatly reducing the corrosion rate.

[0031] (4) Significant improvement in cycle life: The data of the examples show that the zinc-nickel battery using the additive of the present application has a capacity retention rate of more than 88% after 500 cycles at 1C rate, which is much higher than the battery without additive or containing only a single additive.

[0032] (5) The preparation process is advanced, and the product performance is stable: the preparation process combining high-speed shearing and spray drying ensures the uniformity and stability of the product, and the microspherical morphology improves the flowability and dispersibility of the additive. DETAILED DESCRIPTION

[0033] The specific embodiments of the present application are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0034] It should be noted that all reagents and raw materials in the present application are obtained from the market, and the purity of the reagents is analytical pure.

[0035] The double-end amino polyethylene glycol is obtained from Guangzhou Huawha Biological Technology Co., Ltd., and the item number is WH00503.

[0036] Example 1

[0037] The present embodiment provides a composite electrolyte additive for zinc-nickel batteries, which is composed of an interfacial film forming agent, an electric field regulating agent and a bridging component in a mass ratio of 2:0.2:0.8. The interfacial film forming agent is a composite of sodium phytate and sodium dodecyl sulfonate in a mass ratio of 3:1; the electric field regulating agent is cerium acetylacetone; and the bridging component is double-end amino polyethylene glycol (molecular weight 600, amino content 1.0 mmol / g).

[0038] The preparation method comprises the following steps:

[0039] (1) 0.8g of double-end amino polyethylene glycol is weighed and placed in a 50mL beaker, and melted under heating in a 65℃ water bath to obtain liquid A;

[0040] (2) 1.5g of sodium phytate and 0.5g of sodium dodecyl sulfonate are weighed and dispersed in 10mL of deionized water, and homogenized at 10000rpm for 2 minutes to form slurry B;

[0041] (3) 0.2g of cerium acetylacetone is weighed and dissolved in 5mL of anhydrous ethanol to form solution C;

[0042] (4) Under high-speed shearing at 10000rpm, slurry B and solution C are alternately added to liquid A every 30s, and each time the total volume of the corresponding slurry is 8%, and the reaction is carried out at 70℃ for 1.5h;

[0043] (5) After the reaction, spray drying is carried out, the inlet temperature is 165℃, and the outlet temperature is 80℃, to obtain a microspherical composite electrolyte additive;

[0044] (6) The obtained microspheres are aged in an environment with a relative humidity of 60% for 18h.

[0045] The additive prepared in this example was used to prepare zinc-nickel battery electrolyte: the composite additive prepared in this example was added in standard zinc-nickel battery electrolyte (containing 25wt% KOH, 8wt% ZnO and 1wt% LiOH, and the rest being deionized water), and the concentration of the additive was 3g / L.

[0046] Example 2

[0047] This example provides a composite electrolyte additive, which is composed of an interface film forming agent, an electric field regulating agent and a bridging component in a mass ratio of 3:0.5:1.2. The interface film forming agent is a composite of sodium phytate and sodium dodecyl sulfonate in a mass ratio of 2.5:1; the bridging component is a double-end amino polyethylene glycol (molecular weight 1000, amino content 0.9 mmol / g).

[0048] The preparation method comprises the following steps:

[0049] (1) 1.2g of double-end amino polyethylene glycol was weighed and melted at 70°C to obtain liquid A;

[0050] (2) 2.14g of sodium phytate and 0.86g of sodium dodecyl sulfonate were weighed and dispersed in 15mL of deionized water to form slurry B;

[0051] (3) 0.5g of cerium acetylacetone was weighed and dissolved in 8mL of anhydrous ethanol to form solution C;

[0052] (4) Under high-speed shearing at 9000rpm, slurry B and solution C were alternately added to liquid A, each time adding 10% of the total volume of the corresponding slurry, and reacted at 68°C for 2h;

[0053] (5) After the reaction, spray drying was performed with an inlet temperature of 170°C and an outlet temperature of 85°C to obtain a microspherical composite electrolyte additive;

[0054] (6) The obtained microspheres were aged in an environment with a relative humidity of 50% for 24h.

[0055] The additive prepared in this example was used to prepare zinc-nickel battery electrolyte (same as in Example 1), and the concentration of the additive was 4g / L.

[0056] Example 3

[0057] This example provides a composite electrolyte additive, which is composed of an interface film forming agent, an electric field regulating agent and a bridging component in a mass ratio of 1.5:0.3:1.0. The interface film forming agent is a composite of sodium phytate and sodium dodecyl sulfonate in a mass ratio of 4:1; the bridging component is a double-end amino polyethylene glycol (molecular weight 800, amino content 1.1mmol / g).

[0058] The preparation method comprises the following steps:

[0059] (1) Weigh 1.0g of amino-terminated polyethylene glycol and melt it at 62℃ to obtain liquid A;

[0060] (2) Weigh 1.2g of sodium phytate and 0.3g of sodium dodecyl sulfonate, disperse them in 8mL of deionized water to form slurry B;

[0061] (3) Weigh 0.3g of cerium acetylacetone and dissolve it in 6mL of anhydrous ethanol to form solution C;

[0062] (4) Under high-speed shearing at 11000rpm, slurry B and solution C are added alternately to liquid A, with each addition being 5% of the total volume of the slurry. The mixture is then reacted at 72℃ for 1h.

[0063] (5) After the reaction, spray drying is carried out at an inlet temperature of 160°C and an outlet temperature of 75°C to obtain microsphere composite electrolyte additive.

[0064] (6) The obtained microspheres were aged in an environment with a relative humidity of 70% for 12 hours.

[0065] The zinc-nickel battery electrolyte was prepared using the additives in this embodiment (same as in Example 1), with an addition concentration of 2.5 g / L.

[0066] Example 4

[0067] This embodiment provides a composite electrolyte additive, which adds 0.1% by weight of nanocellulose whiskers (250 nm in length) to the formulation of Example 1. The preparation method is basically the same as in Example 1, with the nanocellulose whiskers added after the formation of slurry B, followed by subsequent steps.

[0068] The zinc-nickel battery electrolyte was prepared using the additives in this embodiment (same as in Example 1), with an addition concentration of 3.5 g / L.

[0069] Comparative Example 1

[0070] This comparative example provides a zinc-nickel battery electrolyte, which uses a standard zinc-nickel battery electrolyte (same as in Example 1) without adding any functional additives.

[0071] Comparative Example 2

[0072] This comparative example provides a zinc-nickel battery electrolyte, in which bi-amino-terminated polyethylene glycol (molecular weight 600) is added separately to a standard zinc-nickel battery electrolyte (same as in Example 1) at a concentration of 0.8 g / L.

[0073] Comparative Example 3

[0074] The comparative example provides a zinc-nickel battery electrolyte, in which a sodium phytate and sodium dodecyl sulfonate complex (mass ratio 3:1) is added to the standard zinc-nickel battery electrolyte (same as Example 1), and the addition concentration is 2 g / L.

[0075] Comparative Example 4

[0076] The comparative example provides a zinc-nickel battery electrolyte, in which cerium acetylacetonate is added to the standard zinc-nickel battery electrolyte (same as Example 1), and the addition concentration is 0.2 g / L.

[0077] Comparative Example 5

[0078] The comparative example provides a zinc-nickel battery electrolyte, in which a physical mixture of an interfacial film-forming agent, an electric field regulator, and a bridging component (mass ratio 2:0.2:0.8) is added to the standard zinc-nickel battery electrolyte (same as Example 1), and the addition concentration is 3 g / L, but the mixture is not treated by the preparation method of the application, but is directly added to the electrolyte.

[0079] The electrolytes obtained in Examples 1-4 and Comparative Examples 1-5 are subjected to relevant performance tests, and the test items and methods are as follows, and the performance test results are recorded in Table 1.

[0080] (1) Cycle performance test: the battery is subjected to cycle test under the conditions of 1C charge-discharge rate and 100% DOD, and the capacity retention rate after 500 cycles is recorded.

[0081] (2) Dendrite inhibition effect: the surface morphology of the zinc negative electrode after 100 cycles of the battery is observed by scanning electron microscope, and the dendrite growth is evaluated (evaluation standard: excellent - smooth surface without dendrite; good - slight dendrite; medium - obvious dendrite; poor - serious dendrite and corrosion).

[0082] (3) Corrosion current test: the Tafel curve is tested by an electrochemical workstation, the corrosion current density is calculated, and the zinc corrosion inhibition effect is evaluated.

[0083] (4) High temperature performance test: the capacity retention rate of the battery after 100 cycles at 45°C.

[0084] (5) Rate performance test: the ratio of the 2C discharge capacity to the 0.5C discharge capacity of the battery.

[0085] Table 1 Performance test results

[0086]

[0087] From the data in Table 1, it can be seen that the zinc-nickel batteries of Examples 1-4 of the application are significantly better than the comparative examples in terms of cycle performance, corrosion inhibition, dendrite inhibition, high temperature performance, and rate performance.

[0088] Cycling performance: the capacity retention of batteries of Examples 1-4 were all above 85% after 500 cycles, among which Example 4 reached 89.3%, while Comparative Example 1 was only 45.6%. This indicates that the composite additive of the present application can significantly prolong the cycle life of the battery.

[0089] Corrosion inhibition: the corrosion current density of Examples 1-4 was 9.6-12.5 μA / cm², much lower than that of Comparative Example 1 (45.7 μA / cm²), indicating that the additive of the present application can effectively inhibit the corrosion of zinc negative electrode.

[0090] Dendrite inhibition: SEM observation showed that the surface of zinc negative electrode after cycling of Examples 1-4 was smooth without obvious dendrites; while the surface of zinc negative electrode of Comparative Example 1 had a large number of dendrites and corrosion pits, indicating that the additive of the present application can effectively inhibit dendrites.

[0091] Synergistic effect: Comparative Examples 2, 3 and 4 only added a single component, and the performance was significantly lower than all Examples, proving that there is a significant synergistic effect between the interface film-forming agent, the electric field regulating agent and the bridging component. Comparative Example 5 used physical mixing instead of the preparation method of the present application, and the performance was also lower than all Examples, indicating that the preparation method of the present application is crucial to achieve full reaction between components and the best effect.

[0092] High temperature performance and rate capability: the capacity retention of Examples 1-4 was all above 83% after 100 cycles at 45°C high temperature, and the rate capability was all above 90%, indicating that the additive of the present application can also improve the high temperature performance and high rate discharge capability of the battery.

[0093] In addition, from the comparison of Example 1 and Example 4, it can be seen that after the absence of only 0.1% of the total amount of nanocellulose whiskers, the various performances of the battery, especially the long-term cycle life (capacity retention) and dendrite inhibition effect, have significantly and cannot be ignored. This powerfully proves that the nanocellulose whisker is not an inert filler, it plays a key role as a "structure enhancer" in the composite additive system. It significantly improves the mechanical strength and structural toughness of the composite interface film through its nanoscale fiber network structure, and the bridging component (double-end amino polyethylene glycol) and the interface film-forming agent through hydrogen bonding and other interactions.

[0094] The above describes the preferred embodiments of the present application in detail, but the present application is not limited to the specific details in the above embodiments, and within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, and these simple modifications all belong to the protection scope of the present application. In addition, it should be noted that in the above specific embodiments, various specific technical features described can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not describe various possible combinations again.

[0095] Furthermore, the various embodiments can also be combined, if not in contradiction, as long as they do not deviate from the spirit of the present application, which should be considered as disclosed.

Claims

1. A zinc nickel battery electrolyte additive based on dynamic interfacial modification, characterized in that, The mass ratio of the interface film former, the electric field regulator and the bridging component is (1-5):(0.1-1):(0.5-2); The interface film former is a composite of sodium phytate and sodium dodecyl sulfonate in a mass ratio of (2-5):1; The electric field regulator is cerium acetylacetone; The bridging component is amino-terminated polyethylene glycol; The preparation method of the electrolyte additive comprises the following steps: The bridging component is heated to 60-80℃ to melt, obtaining liquid A; The interface film former is dispersed in deionized water to form homogeneous slurry B; The electric field regulator is dissolved in an organic solvent to form solution C; Under high-speed shearing, slurry B and solution C are alternately added to liquid A, and reacted at 65-75℃ for 1-2h; After the reaction, spray drying is performed to obtain microspherical electrolyte additives.

2. The dynamic interfacial modification based electrolyte additive for zinc nickel battery of claim 1, wherein, The mass ratio of the interface film former, the electric field regulator and the bridging component is (2-3):(0.2-0.5):(0.8-1.2).

3. The dynamic interfacial modification based electrolyte additive for zinc nickel battery of claim 1, wherein, The molecular weight of the amino-terminated polyethylene glycol is 600-1000, and the amino content is not less than 0.8 mmol / g.

4. The dynamic interfacial modification based electrolyte additive for zinc nickel battery of claim 1, wherein, The mass ratio of sodium phytate and sodium dodecyl sulfonate is 3:

1.

5. The dynamic interfacial modification based electrolyte additive for zinc nickel batteries of claim 1, wherein, It also contains 0.05%-0.2% of nanocellulose whiskers based on the total mass of the additive, with a length of 100-500 nm.

6. The dynamic interfacial modification based electrolyte additive for zinc nickel batteries of claim 1, wherein, The amino-terminated polyethylene glycol is double-terminated amino polyethylene glycol.

7. The dynamic interfacial modification based electrolyte additive for zinc nickel battery of claim 1, wherein, The rotation speed of the high-speed shearing is 8000-12000 rpm, and the frequency of alternating addition is 30s switching each time, and the total volume of the corresponding slurry is 5%-10% each time.

8. The dynamic interfacial modification based electrolyte additive for zinc nickel battery of claim 1, wherein, The inlet temperature of the spray drying is 150-180℃, and the outlet temperature is 70-90℃.

9. The dynamic interfacial modification based electrolyte additive for zinc nickel batteries of claim 1, wherein, After the spray drying, the obtained microspheres are aged in an environment with a relative humidity of 50%-70% for 12-24h.

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