Layered liquid crystal electrolyte based on dynamic self-assembly strategy and preparation method and application thereof

Abstract

The invention discloses a layered liquid crystal electrolyte based on a dynamic self-assembly strategy and a preparation method and application thereof, and belongs to the technical field of new energy materials, and the preparation method comprises the following steps: uniformly mixing dodecyl non-glycol ether and n-decanol according to a mass ratio, heating and centrifuging to a homogeneous phase to obtain a mixed element; dropwise adding a zinc chloride aqueous solution into the mixed element, carrying out vortex mixing, and centrifuging to remove bubbles; placing the sample in a constant-temperature environment for standing, and screening a phase region with anisotropic characteristics through a polarizing microscope; and continuously carrying out constant-temperature self-assembly on the screened sample, and representing the lamellar liquid crystal structure through a polarized optical microscope and small-angle X-ray scattering. A two-dimensional layered liquid crystal structure is constructed through synergistic self-assembly of the surfactant and the solvent, a zinc ion source is provided in combination with the zinc chloride aqueous solution, and the ion transmission efficiency and the thermal stability are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of new energy material technology, and in particular to a layered liquid crystal electrolyte based on a dynamic self-assembly strategy, and a preparation method and application thereof, which are particularly suitable for electrochemical energy storage systems such as aqueous zinc ion batteries. Background Art

[0002] With the rapid development of new energy technologies, zinc-ion batteries have attracted considerable attention due to their high safety, low cost, and large-scale energy storage potential. However, traditional liquid electrolytes present technical challenges such as volatility and leakage risks, while solid-state electrolytes are limited by technical issues such as low ionic conductivity and poor interfacial compatibility, which restrict the further promotion of zinc-ion batteries. Lyotropic liquid crystal materials can form long-range, ordered ion transport channels through molecular self-assembly, combining the fluidity of liquid electrolytes with the structural stability of solid electrolytes. However, existing liquid crystal electrolytes tend to focus on disordered or one-dimensional structures, resulting in insufficient ion transport efficiency. Summary of the Invention

[0003] Technical problems to be solved: In response to the technical problems existing in the background technology, the present invention provides a lamellar liquid crystal electrolyte based on a dynamic self-assembly strategy, and its preparation method and application. Through the coordinated self-assembly of surfactants and solvents, a two-dimensional lamellar liquid crystal structure is constructed, and a zinc chloride aqueous solution is combined to provide a zinc ion source, which significantly improves the ion transmission efficiency and thermal stability.

[0004] Technical solution: The method for preparing a layered liquid crystal electrolyte based on a dynamic self-assembly strategy described in the present invention comprises the following steps: Step 1: Mix dodecyl non-glycol ether and n-decanol in a mass ratio of (2.3-4):1, heat at 65±2°C and centrifuge until a homogeneous phase is obtained to obtain a mixed primitive; Step 2: Add a 1 mol / L zinc chloride aqueous solution dropwise to the mixed element obtained in step 1, vortex mix, and centrifuge at 3000-5000 rpm for 5-10 minutes to remove bubbles; Step 3: The sample obtained in step 2 was placed in a constant temperature environment of 25±0.5°C for 2 hours, and the phase region with anisotropic characteristics was screened by polarizing microscopy; Step 4: The screened samples were further self-assembled at a constant temperature of 25±0.5°C for 24 to 168 hours, and their lamellar liquid crystal structures were characterized by polarized optical microscopy and small-angle X-ray scattering.

[0005] Preferably, the specific method of adding the zinc chloride aqueous solution in step 2 is: weighing the mass of the centrifuge tube after each addition to control the amount of solution added, and repeating the vortex mixing, centrifugation and constant temperature balancing operation steps.

[0006] Preferably, the interlayer spacing of the lamellar liquid crystal electrolyte obtained in step 4 is 4.2-4.8 nm, and its room temperature ionic conductivity is 0.38×10 -3 S / cm.

[0007] Preferably, the lamellar liquid crystal electrolyte obtained in step 4 is composed of dodecyl non-ethylene glycol ether, n-decanol and zinc chloride aqueous solution, wherein the mass percentage of the zinc chloride aqueous solution is 37.5-41.2%.

[0008] The present invention discloses a lamellar liquid crystal electrolyte prepared by any of the above methods. The lamellar liquid crystal electrolyte has a two-dimensional long-range ordered lamellar mesostructure and achieves structural stability through intermolecular forces.

[0009] The present invention also discloses an application of the above-mentioned layered liquid crystal electrolyte in an aqueous zinc ion battery, a flexible supercapacitor or a wearable electronic device.

[0010] Compared with the prior art, the present invention has the following beneficial effects: 1. The method of the present invention successfully constructs a two-dimensional layered liquid crystal mesostructure with long-range order through the molecular cooperative self-assembly of the ternary system of dodecyl non-ethylene glycol ether / n-decyl alcohol / zinc chloride aqueous solution. Its periodically arranged nanochannels provide a directional transmission path for zinc ions. The two-dimensional layered structure provides an efficient ion transmission channel. Compared with the traditional disordered liquid crystal system, the room temperature ionic conductivity reaches 0.38×10 -3 S / cm, the ionic conductivity is significantly improved; 2. The method of the present invention introduces a gradient drop-addition combined with a step-by-step centrifugation process (3000-5000 rpm, 5-10 min), which effectively regulates the kinetics of liquid crystal interface formation and increases the phase purity to over 98%. The multiple hydrogen bond network enhances structural stability and avoids channel defects caused by local concentration overload. 3. The layered liquid crystal electrolyte prepared by the present invention has both flexible and processable characteristics, and can be adapted to the roll-to-roll manufacturing process, providing a material basis for the development of flexible zinc-ion batteries. The size of the layered channel can be adjusted (by adjusting the surfactant / solvent mass ratio to achieve 3.5-4.2 nm interlayer spacing control), which can be extended to other multivalent metal ions (such as Mg 2+ 、Al 3+ ) battery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is the ternary phase diagram of the aqueous solution of dodecyl non-glycol ether / n-decyl alcohol / zinc chloride at 25° C. of the present invention; Figure 2 is the structural formula of the dodecyl non-glycol ether of the present invention; Figure 3Polarized optical microscopy (POM) images of lamellar liquid crystals constructed with dodecyl non-glycol ether at 25° C. according to the present invention ((a) Example 1; (b) Example 2; (c) Example 3; (d) Example 4); Figure 4 The lamellar liquid crystal X-ray scattering (SAXS) pattern of dodecyl non-glycol ether at 25°C was constructed for the present invention; Figure 5 This is the AC impedance diagram of lamellar liquid crystal constructed by dodecyl non-ethylene glycol ether at 25°C of the present invention. DETAILED DESCRIPTION

[0012] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following Figures 1 to 5 The technical solutions of the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0013] The present invention discloses a technical solution: a method for preparing a layered liquid crystal electrolyte based on a dynamic self-assembly strategy, comprising the following steps: Step 1: Mix dodecyl non-glycol ether and n-decanol in a mass ratio of (2.3-4):1, heat at 65±2°C and centrifuge until a homogeneous phase is obtained to obtain a mixed primitive; Step 2: Add a 1 mol / L zinc chloride aqueous solution dropwise to the mixed element obtained in step 1, vortex mix, and centrifuge at 3000-5000 rpm for 5-10 minutes to remove bubbles. The specific method of adding the zinc chloride aqueous solution is as follows: weigh the centrifuge tube after each addition to control the amount of solution added, and repeat the vortex mixing, centrifugation, and constant temperature balancing steps; Step 3: The sample obtained in step 2 was placed in a constant temperature environment of 25±0.5°C for 2 hours, and the phase region with anisotropic characteristics was screened by polarizing microscopy; Step 4: The screened samples were further self-assembled at a constant temperature of 25±0.5℃ for 24~168h. The lamellar liquid crystal structure was characterized by polarized optical microscopy and small-angle X-ray scattering. The interlayer spacing of the lamellar liquid crystal electrolyte was 4.2~4.8nm, and its room temperature ionic conductivity was 0.38×10 -3 The lamellar liquid crystal electrolyte is composed of dodecyl non-ethylene glycol ether, n-decyl alcohol and a zinc chloride aqueous solution, wherein the mass percentage of the zinc chloride aqueous solution is 37.5-41.2%.

[0014] The present invention discloses a lamellar liquid crystal electrolyte prepared by any of the above methods. The lamellar liquid crystal electrolyte has a two-dimensional long-range ordered lamellar mesostructure and achieves structural stability through intermolecular forces.

[0015] The present invention also discloses an application of the above-mentioned layered liquid crystal electrolyte in an aqueous zinc ion battery, a flexible supercapacitor or a wearable electronic device.

[0016] The sources of materials in the following examples of the present invention are as follows: Dodecyl non-glycol ether, n-decyl alcohol and zinc chloride were purchased from Shanghai Aladdin Biochemical Co., Ltd. The molecular structure of dodecyl non-glycol ether is as follows: Figure 2 As shown; the zinc chloride aqueous solution uses homemade double distilled water.

[0017] Example 1: The liquid crystal electrolyte of the present invention comprises 43.75 wt % of dodecyl glycol ether, 18.75 wt % of n-decanol, and 37.5 wt % of an aqueous zinc chloride solution. The preparation method comprises the following steps: uniformly mixing the dodecyl glycol ether and the n-decanol, heating at 65±2°C, and centrifuging until homogeneous to obtain a mixed element; adding a 1 mol / L aqueous zinc chloride solution dropwise to the mixed element, vortex-mixing, and centrifuging at 3500 rpm for 6 minutes to remove air bubbles; the sample is placed in a constant temperature environment at 25±0.5°C for 2 hours, and anisotropic phase regions are screened using a polarizing microscope; the screened sample is further self-assembled at 25±0.5°C for 72 hours, and the lamellar liquid crystal structure S1 is characterized by polarizing optical microscopy and small-angle X-ray scattering.

[0018] Example 2: The liquid crystal electrolyte of the present invention comprises 41.2 wt % of dodecyl glycol ether, 17.6 wt % of n-decanol, and 41.2 wt % of a zinc chloride aqueous solution. The preparation method comprises the following steps: uniformly mixing the dodecyl glycol ether and n-decanol, heating at 65±2°C, and centrifuging until homogeneous to obtain a mixed element; adding a 1 mol / L zinc chloride aqueous solution dropwise to the mixed element, vortex-mixing, and centrifuging at 3500 rpm for 6 minutes to remove bubbles; the sample is incubated at a constant temperature of 25±0.5°C for 2 hours, and anisotropic phase regions are screened using a polarizing microscope; the screened sample is then self-assembled at a constant temperature of 25±0.5°C for 72 hours, and its lamellar liquid crystal structure S2 is characterized by polarizing optical microscopy and small-angle X-ray scattering.

[0019] Example 3: The liquid crystal electrolyte of the present invention comprises 50 wt % of dodecyl glycol ether, 12.5 wt % of n-decanol, and 37.5 wt % of an aqueous zinc chloride solution. The preparation method comprises the following steps: uniformly mixing the dodecyl glycol ether and the n-decanol, heating at 65±2°C, and centrifuging until homogeneous to obtain a mixed element; adding a 1 mol / L aqueous zinc chloride solution dropwise to the mixed element, vortex-mixing, and centrifuging at 3500 rpm for 6 minutes to remove air bubbles; the sample is placed in a constant temperature environment at 25±0.5°C for 2 hours, and anisotropic phase regions are screened using a polarizing microscope; the screened sample is further self-assembled at 25±0.5°C for 72 hours, and the lamellar liquid crystal structure S3 is characterized by polarizing optical microscopy and small-angle X-ray scattering.

[0020] Example 4: The liquid crystal electrolyte of the present invention comprises 47.1 wt % of dodecyl glycol ether, 11.7 wt % of n-decanol, and 41.2 wt % of a zinc chloride aqueous solution. The preparation method comprises the following steps: uniformly mixing the dodecyl glycol ether and n-decanol, heating at 65±2°C, and centrifuging until homogeneous to obtain a mixed element; adding a 1 mol / L zinc chloride aqueous solution dropwise to the mixed element, vortex-mixing, and centrifuging at 3500 rpm for 6 minutes to remove air bubbles; the sample is incubated at 25±0.5°C for 2 hours, and anisotropic phase regions are screened using a polarizing microscope; the screened sample is further self-assembled at 25±0.5°C for 72 hours, and the lamellar liquid crystal structure S4 is characterized by polarizing optical microscopy and small-angle X-ray scattering.

[0021] Example 5: The liquid crystal electrolyte of the present invention comprises 46.7 wt % of dodecyl glycol ether, 20 wt % of n-decanol, and 33.3 wt % of an aqueous zinc chloride solution. The preparation method comprises the following steps: uniformly mixing the dodecyl glycol ether and the n-decanol, heating at 65±2°C, and centrifuging until homogeneous to obtain a mixed element; adding a 1 mol / L aqueous zinc chloride solution dropwise to the mixed element, vortex-mixing, and centrifuging at 3000 rpm for 10 minutes to remove bubbles; the sample is incubated at 25±0.5°C for 2 hours, and anisotropic phase regions are screened using a polarizing microscope; the screened sample is then self-assembled at 25±0.5°C for 24 hours, and its lamellar liquid crystal structure S5 is characterized by polarizing optical microscopy and small-angle X-ray scattering.

[0022] Example 6: The liquid crystal electrolyte of the present invention comprises 53.4 wt % of dodecyl glycol ether, 13.3 wt % of n-decanol, and 33.3 wt % of an aqueous zinc chloride solution. The preparation method comprises the following steps: uniformly mixing the dodecyl glycol ether and the n-decanol, heating at 65±2°C, and centrifuging until the mixture is homogeneous to obtain a mixed element; adding a 1 mol / L aqueous zinc chloride solution dropwise to the mixed element, vortex-mixing, and centrifuging at 5000 rpm for 5 minutes to remove bubbles; the sample is incubated at a constant temperature of 25±0.5°C for 2 hours, and anisotropic phase regions are screened using a polarizing microscope; the screened sample is further self-assembled at a constant temperature of 25±0.5°C for 168 hours, and the lamellar liquid crystal structure S6 is characterized by polarizing optical microscopy and small-angle X-ray scattering.

[0023] A certain amount of dodecyl non-glycol ether and decanol were weighed into a colorimetric tube in a mass ratio ranging from 10:0 to 0:10. The tube was heated in a water bath at 65°C and repeatedly vortexed and centrifuged to obtain a uniformly mixed solution. A 1M aqueous zinc chloride solution was then added dropwise, heated in a water bath at 65°C, and repeatedly vortexed and centrifuged. The sample was then equilibrated in a 25°C constant temperature bath for 2 hours until the sample stabilized. Phase changes and the appearance of the sample were observed and recorded. The equilibration time was extended near the phase boundary to determine the phase behavior of the system and draw a phase diagram. The sample point to be prepared was selected within the liquid crystal region of the phase diagram. The sample was weighed into a colorimetric tube according to the content of each component at the sample point. The sample was heated in a water bath at 65°C, repeatedly centrifuged and vortexed, and then placed in a 25°C water bath for at least six days for further property studies. The phase boundary is determined by observing or testing the color, transparency, viscosity, hardness and other data of the prepared liquid crystal sample at 25°C, and a ternary phase diagram of dodecyl non-ethylene glycol ether / n-decyl alcohol / zinc chloride aqueous solution is drawn (e.g. Figure 2 As shown in the figure), the sample in the blue area of ​​the phase diagram appears colorless and transparent, with a viscoelastic inverted and non-flowing state.

[0024] A polarizing microscope (DMLP, Leica, Germany) was used with a maximum magnification of 20,000 times. A small amount of the samples prepared in Examples 1 to 5 was placed between two clean glass slides and allowed to stand at a constant temperature for 10 minutes. The polarization texture of the liquid crystal samples was observed and recorded using the polarizing microscope. The polarization texture of the liquid crystal electrolyte samples prepared in Examples 1 to 4 is shown in FIG. Figure 3As shown in the figure, under a constant temperature of 25°C, the polarization textures of the samples all show a typical Maltese cross interference pattern, which is specifically manifested as a characteristic morphology of alternating light and dark concentric rings and a four-fold symmetrical cross extinction shadow interwoven. This phenomenon originates from the birefringence effect caused by the unique molecular layered arrangement of lamellar liquid crystals. When the normal direction of the lamellar structure is at an angle of 45° to the polarization axis, its periodic layered structure will produce regular interference with the polarized light field. This characteristic morphology indicates that the sample has formed a highly ordered lamellar mesomorphic phase under this temperature condition. Its molecules are arranged in a liquid-like disorder within the parallel layers, while maintaining periodic long-range ordered stacking between the layers in the vertical direction. It can be determined that the prepared liquid crystal electrolyte sample is a lamellar liquid crystal.

[0025] The liquid crystal samples prepared in Examples 1 to 4 were sealed in a sample cell and measured using a NanoSTAR small-angle X-ray scattering instrument (Bruker, Germany). The X-ray generator (PW3830) generated copper Kα X-rays (filtered by a nickel-tungsten baffle) with a wavelength of 1.542 Å. The distance from the liquid crystal sample to the detector was 27.70 cm. The liquid crystal sample was exposed for 10 minutes to measure its phase structure and lattice parameters. The X-ray diffraction patterns of the liquid crystal electrolyte samples prepared in Examples 1 to 4 are shown in FIG. Figure 4 As shown, samples S1-S4 exhibit typical Bragg diffraction characteristics in the low-angle region, with the square values ​​of the scattering vector ratios q1:q2:q3:q4 showing an integer ratio relationship of 1:::. This diffraction pattern strictly follows the mathematical law of the Bragg equation nλ=2d sinθ, where the interlayer spacing d values ​​corresponding to each diffraction peak show a clear geometric progression feature. This diffraction peak sequence with a strict geometric series relationship clearly indicates the presence of a lamellar liquid crystal phase structure in samples S1-S4. The above experimental data show that the periodic parameters of the lamellar liquid crystal electrolyte maintain a high degree of order, and the interlayer molecular arrangement shows a periodic alternating orientation feature, providing an important structural characterization basis for subsequent research on the self-assembly behavior and phase transition dynamics of this liquid crystal electrolyte system.

[0026] Ionic conductivity was measured using a Bio-logic VMP3 electrochemical workstation and EC-lab software. A symmetrical stainless steel (SS) two-electrode system (SS|SS) was used for testing. The electrochemical workstation recorded the AC impedance spectrum over a frequency range of 0.1–10,000 Hz. The functional relationship between ionic conductivity σ and solution resistance R was established based on the following formula: ; Where: L is the electrode spacing; A is the effective electrode contact area; combined with the electrolyte resistance value corresponding to the intersection of the high-frequency region and the real axis in the Nyquist spectrum, the ionic conductivity parameters of each electrolyte system can be calculated.

[0027] Ionic conductivity is a core parameter for evaluating electrolyte performance. Its value directly reflects the kinetic characteristics of ion transport in the electrolyte. The ohmic impedance characteristics of the lamellar liquid crystal electrolyte are systematically characterized by AC impedance spectroscopy using a symmetrical SS electrode system (SS||SS). Figure 5 As shown. Figure 5 As shown in (a), the ohmic impedance (RΩ) is determined by the intersection of the high-frequency impedance spectrum curve and the real axis. This parameter essentially characterizes the intrinsic impedance characteristics of the electrolyte. As the zinc chloride content in the electrolyte system increases (sample S1-sample S4), the ohmic impedance value of the electrolyte system shows a regular downward trend, gradually decreasing from the initial 37Ω•cm² to 25Ω•cm 2 , confirming that the migration resistance of anions and cations in the liquid crystal electrolytes prepared in Examples 1 to 4 of the present invention significantly decreases with increasing electrolyte concentration.

[0028] The ionic conductivity σ of the liquid crystal electrolytes with different ratios prepared in Examples 1 to 4 was further calculated based on the Arrhenius equation, as shown in FIG. Figure 5 As shown in (b), when the concentration of zinc chloride solution increases from 37.5wt% to 41.2wt%, the ionic conductivity of the lamellar liquid crystal electrolyte shows a significant enhancement trend, from the initial 0.2×10 -3 S / cm increases linearly to 0.38×10 - 3 S / cm (sample S4), this conductivity improvement can be attributed to: (1) the increase in electrolyte concentration leads to an increase in carrier density; (2) the regular arrangement of the liquid crystal phase structure reduces the ion transport barrier; (3) the reconstruction of the solvation layer optimizes the ion migration channel.

[0029] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a layered liquid crystal electrolyte based on a dynamic self-assembly strategy, characterized in that: The following steps are involved: Step 1: Mix dodecyl non-glycol ether and n-decanol in a mass ratio of (2.3-4):1, heat at 65±2°C and centrifuge until a homogeneous phase is obtained to obtain a mixed primitive; Step 2: Add a 1 mol / L zinc chloride aqueous solution dropwise to the mixed element obtained in step 1, vortex mix, and centrifuge at 3000-5000 rpm for 5-10 minutes to remove bubbles; Step 3: The sample obtained in step 2 was placed in a constant temperature environment of 25±0.5°C for 2 hours, and the phase region with anisotropic characteristics was screened by polarizing microscopy; Step 4: The screened samples were further self-assembled at a constant temperature of 25±0.5°C for 24 to 168 hours, and their lamellar liquid crystal structures were characterized by polarized optical microscopy and small-angle X-ray scattering.

2. The method for preparing a layered liquid crystal electrolyte based on a dynamic self-assembly strategy according to claim 1, characterized in that: The specific method of adding the zinc chloride aqueous solution in step 2 is as follows: weigh the mass of the centrifuge tube after each addition to control the amount of solution added, and repeat the vortex mixing, centrifugation and constant temperature balancing operation steps.

3. The method for preparing a layered liquid crystal electrolyte based on a dynamic self-assembly strategy according to claim 1, characterized in that: The interlayer spacing of the lamellar liquid crystal electrolyte obtained in step 4 is 4.2~4.8nm, and its room temperature ionic conductivity is 0.38×10 -3 S / cm.

4. The method for preparing a layered liquid crystal electrolyte based on a dynamic self-assembly strategy according to claim 1, characterized in that: The lamellar liquid crystal electrolyte obtained in step 4 is composed of dodecyl non-ethylene glycol ether, n-decyl alcohol and a zinc chloride aqueous solution, wherein the mass percentage of the zinc chloride aqueous solution is 37.5-41.2%.

5. A lamellar liquid crystal electrolyte prepared according to the method of any one of claims 1 to 4, characterized in that: The lamellar liquid crystal electrolyte has a two-dimensional long-range ordered lamellar mesoscopic structure, and achieves structural stability through intermolecular forces.

6. Use of the layered liquid crystal electrolyte according to claim 5 in aqueous zinc ion batteries, flexible supercapacitors or wearable electronic devices.

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