A fluid power generation fiber with a two-phase gradient structure, a preparation method and applications thereof

Abstract

The application discloses a kind of fluid power generation fibers with two-phase gradient structure and preparation method and application thereof, belong to the technical field of fiber materials, the fluid power generation fiber includes the porous network-like cellulose sponge layer of core and the carbon black nano-particle accumulation layer located outside the core;The cellulose sponge layer has micron-sized pores, and the pore decreases from center to edge;The carbon black nano-particle accumulation layer has nanometer-sized pores;Negatively charged cellulose micro-nano channel forms overlapping double electric layer, when fluid is oriented in the fiber transmission will promote the movement of ion with positive charge to form electric current, and accumulate to generate certain potential difference, so using the interaction of fluid and fiber can realize continuous green power generation, can power small electronic equipment, and is expected to play an important role in portable wearable self-powered system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fiber materials, and particularly relates to a fluid power generation fiber with a two-phase gradient structure, a preparation method and application. BACKGROUND

[0002] Natural biomass materials such as cellulose and chitin have abundant reserves and wide sources, and become new degradable and renewable fiber raw materials to replace fossil raw materials. At present, the methods for constructing regenerated fibers mainly include top-down and bottom-up strategies. The top-down strategy refers to separating and extracting nanofibers or nanocrystals from raw materials as spinning precursors; the bottom-up strategy refers to dissolving natural fibers and then making them grow into fibers in a gel. The dissolving and gelation process is simple, fast and low in cost, and is a common means for constructing fiber materials.

[0003] Common fiber construction methods include dry spinning, wet spinning, microfluidic spinning, dry-jet wet spinning and the like. The fiber structure prepared by the traditional spinning process is single, and only the characteristics of the spinning raw material itself are utilized to meet the application. At present, more and more application scenarios require fibers with special structures. The microfluidic spinning technology prepares fibers with specific structures through precise control of the spinning flow channel, and endows the fibers with new applications in the fields of light, heat, electricity and the like.

[0004] Some power generators, sensors and energy collection devices are developed by utilizing the energy generated from the interaction between flowing liquid and solid. The working mechanism of these devices mostly depends on flow potential, that is, when an electrolyte is oriented through a narrow channel, an electric current is generated, and then opposite charges are continuously accumulated at both ends of the channel to generate a potential difference. For example, the volatile liquid power generation device proposed in CN 204190653U and the power generation device based on carbon materials and the manufacturing method thereof proposed in CN 105591166B both utilize the interaction between fluid and carbon materials to realize continuous and high-voltage electric energy output. However, the specific device limits the use scenarios. SUMMARY

[0005] To solve the above technical problems, the present application provides a fluid power generation fiber with a two-phase gradient structure. The fluid power generation fiber includes a porous network-like cellulose sponge layer of a core part and a carbon black nanoparticle accumulation layer located outside the core part. The negatively charged cellulose micro-nano channels form overlapping double electric layers. When the fluid is oriented in the fiber, the positively charged ions move to form an electric current, and a certain potential difference is accumulated. Therefore, the interaction between the fluid and the fiber can realize continuous green power generation, can power small electronic devices, and is expected to play an important role in portable wearable self-powered systems.

[0006] The application further provides a preparation method of the fluid power generation fiber with the two-phase gradient structure.

[0007] The application further provides application of the fluid power generation fiber with the two-phase gradient structure as a fluid power generation material.

[0008] To achieve the above object, the application adopts the following technical scheme:

[0009] The application provides a fluid power generation fiber with a two-phase gradient structure, which comprises a porous network cellulose sponge layer of a core part and a carbon black nanoparticle accumulation layer outside the core part.

[0010] The diameter of the fluid power generation fiber is 150-350 microns.

[0011] The central axial fluid transmission rate of the fluid power generation fiber is 2-5 mm / s, the edge axial fluid transmission rate is 0.2-0.4 mm / s, and the radial fluid transmission rate is 0.1-0.4 mm / s.

[0012] The fluid power generation fiber can generate electricity in a fluid with ionization properties.

[0013] The application further provides a preparation method of the fluid power generation fiber with the two-phase gradient structure, which comprises the following steps:

[0014] S1. preparing a mixed aqueous solution I, which is a mixed aqueous solution of an inorganic base and urea; the mixed aqueous solution I is used as a solvent;

[0015] S2. preparing a mixed suspension II, which is a mixed suspension obtained by ball milling after dispersing carbon black nanoparticles in the mixed aqueous solution I; the mixed suspension II is used as a sheath injection;

[0016] S3. preparing a mixed aqueous solution III, which is a mixed aqueous solution of an inorganic acid and a metal salt of the inorganic acid; the mixed aqueous solution III is used as a coagulation bath;

[0017] S4. under a cooling condition, dissolving a fiber raw material in the mixed aqueous solution I, and after centrifugal defoaming, obtaining a solution A;

[0018] S5. To the solution A, a cross-linking agent is added, and after cooling the reaction and centrifugation to remove bubbles, a solution B is obtained;

[0019] S6. The solution B and the mixed suspension II are pumped into the core channel and the sheath channel of the microfluidic chip, respectively, and then the effluent is collected in a mixed aqueous solution III, which is centrifuged, washed, and dried to obtain the fluid power generation fiber having a two-phase gradient structure.

[0020] In step S1, the inorganic base is at least one of lithium hydroxide, sodium hydroxide, and potassium hydroxide, and is preferably lithium hydroxide.

[0021] In step S1, the mass percentage concentrations of the inorganic base and urea in the mixed aqueous solution I are 7-15% and 3-30%, respectively, and are preferably 8% and 15%, respectively.

[0022] In step S2, the mass percentage concentration of the carbon black nanoparticles in the mixed suspension II is 1-2%, and is preferably 2%.

[0023] In step S2, the rotation speed of the ball mill is 500-800 rpm, and the ball milling time is 25-35 min.

[0024] In step S3, the inorganic acid is sulfuric acid, and the metal salt of the inorganic acid is sodium sulfate; in the mixed aqueous solution III, the mass percentage concentrations of the inorganic acid and the metal salt of the inorganic acid are 5-10% and 1-5.5%, respectively, and are preferably 5% and 5%, respectively.

[0025] In step S4, the fiber raw material is at least one of cellulose, chitin, chitosan, and cotton linter; and the mass percentage concentration of the fiber raw material in the mixed aqueous solution I is 1.0-5.0%, and is preferably 1.0-2.0%.

[0026] In step S4, the cooling includes cooling the solvent and the fiber raw material at a temperature of about -20 to -30°C for 2-5 h, and then mixing and stirring the fiber raw material and the cooled solvent at a temperature ≤ room temperature.

[0027] In step S5, the ratio of the solution A to the cross-linking agent is 100 g:(1.0-2.0) ml; and the cross-linking agent is epichlorohydrin.

[0028] In step S5, the cooling reaction is performed at a temperature of -10 to 0°C for 1.5-2 h.

[0029] In step S6, the pumping speed of the solution B is 200-350 μL / min; and the pumping speed of the mixed suspension II is 250-400 μL / min.

[0030] In step S6, the pump-in speed needs to satisfy: mixed suspension II >= solution B.

[0031] In step S6, the microfluidic chip comprises a core layer channel 100, a sheath layer channel 200 and a mixing channel 300; the core layer channel 100 and the mixing channel 300 are on the same vertical line and communicate with each other, and the sheath layer channel 200 is on the horizontal line and is arranged in a cross shape with the core layer channel 100 and the mixing channel 300. Figure 3 As shown in the figure.

[0032] The fluid power generation fiber with the two-phase gradient structure can be applied to small electronic devices as a fluid power generation material.

[0033] The fluid power generation fiber with the two-phase gradient structure comprises a porous network-like cellulose sponge layer in a core part and a carbon black nanoparticle accumulation layer outside the core part; the cellulose sponge layer has micrometer-sized pores, and the pores decrease from the center to the edge; and the carbon black nanoparticle accumulation layer has nanometer-sized pores. The negatively charged cellulose micro-nano channels and the formed overlapping double layers promote the movement of positively charged ions to form an electric current and accumulate a certain potential difference when the fluid is directionally transmitted in the fiber. Therefore, the interaction between the fluid and the fiber can realize continuous green power generation and can power small electronic devices, and is expected to play an important role in portable wearable self-powered systems.

[0034] The preparation method of the fluid power generation fiber with the two-phase gradient structure comprises the following steps: preparing a solution B containing fiber raw materials, preparing a mixed suspension II containing carbon black nanoparticles, and mixing the solution B and the mixed suspension II in a microfluidic chip. Figure 3 As shown in the figure, the solution B containing fiber raw materials is pumped into the core layer channel 100, the mixed suspension II containing carbon black nanoparticles is pumped into the sheath layer channel 200, and then the two are mixed in the mixing channel 300, and then flow out to the mixed aqueous solution III for solidification, centrifugation, washing and drying to obtain the fluid power generation fiber with the two-phase gradient structure. Due to the communication between the core layer channel and the sheath layer channel and the dynamic diffusion effect, the systems in the two channels will contact each other during the spinning process, the fiber raw materials (cellulose) are wrapped and extruded by the carbon black nanoparticles to form a relatively dense outer layer, there is a region where the cellulose and the carbon black nanoparticles are tightly intertwined, and the orientation shearing effect makes the fiber arrange and grow along the extension direction of the mixing channel 300; the cellulose in the core layer channel is extruded and scoured by the sheath layer injection, the pores decrease from the center to the edge, and a gradient structure is formed.

[0035] The fluid power generation fiber with two-phase gradient structure provided by the application has a double electric layer formed by overlapping of the negatively charged cellulose micro-nano channel and the carbon black nano channel, when one end of the fiber is immersed in a fluid, the negatively charged cellulose channel can cause ionization of the fluid water molecules, the double electric layer allows only the positively charged ions to pass, the ions are continuously rubbed with the outer carbon black nano particles during the transmission to induce charge separation, the good hydrophilicity of the cellulose promotes the water to carry the positive ions to rapidly transmit along the fiber axis, thereby forming a flow current in the fiber axis, the directional movement of the ions forms a transient and stable potential difference between the two ends of the fiber, and fluid power generation is realized.

[0036] Compared with the prior art, the application has the following beneficial effects:

[0037] The fluid power generation fiber provided by the application has a novel structure, can realize green power generation by being immersed in a fluid with ionization properties, can supply power for small electronic devices, and is expected to play an important role in portable wearable self-powered systems.

[0038] The preparation method of the fluid power generation fiber provided by the application is simple, and the two-phase structure of the prepared fluid power generation fiber is controllable. DETAILED DESCRIPTION

[0039] Figure 1 The SEM image of the fluid power generation fiber obtained in Example 1 is shown in the figure.

[0040] Figure 2 The SEM image of the fluid power generation fiber obtained in Example 1 is shown in the figure.

[0041] Figure 3 The structure schematic diagram of the microfluidic chip used in the application is shown in the figure, wherein 100 is a core layer channel, 200 is a sheath layer channel, and 300 is a mixing channel.

[0042] Figure 4 The electrical performance test results of the fluid power generation fiber obtained in Example 1 are shown in the figure.

[0043] Figure 5 The water transmission performance test results of the fluid power generation fiber obtained in Example 1 are shown in the figure.

[0044] Figure 6 The SEM image of the fluid power generation fiber obtained in Example 2 is shown in the figure.

[0045] Figure 7 The SEM image of the fluid power generation fiber obtained in Example 3 is shown in the figure.

[0046] Figure 8 The SEM image of the regenerated fiber obtained in Comparative Example 1 is shown in the figure.

[0047] Figure 9 The strength test results of the fluid power generation fibers obtained in Examples 1 to 3 are shown in the figure.

[0048] Figure 10 Performance evaluation results of the fluid power generation fiber string for powering small electronic devices in the application example; DETAILED DESCRIPTION

[0049] The application will be described in detail below with reference to examples.

[0050] Example 1

[0051] A method for preparing a fluid power generation fiber with a two-phase gradient structure, the steps are as follows:

[0052] S1. Take 80 g of lithium hydroxide and 150 g of urea, add 770 mL of ultrapure water, stir and dissolve to obtain a mixed aqueous solution I;

[0053] S2. Mix 98 g of mixed aqueous solution I and 2 g of carbon black nanoparticles, ball mill at 500 rpm for 30 min to obtain a mixed suspension II;

[0054] S3. Prepare a mixed aqueous solution of sulfuric acid and sodium sulfate, obtain a mixed aqueous solution III, wherein the concentration of sulfuric acid is 10 wt%, and the concentration of sodium sulfate is 5 wt%;

[0055] S4. Place 95 g of mixed aqueous solution I and 5 g of cotton linters (natural cellulose) in a -25℃ cooling environment for 2 h;

[0056] S5. Mix the mixed aqueous solution I and cotton linters cooled in step S4, stir at 1500 rad / min for 5 min to obtain a transparent cellulose solution;

[0057] S6. Centrifuge the cellulose solution obtained in step S5 to obtain solution A, wherein the centrifugal speed is 8000 rad / min, the time is 10 min, and the temperature is 0℃;

[0058] S7. Add a crosslinking agent, epoxy chloropropane, to solution A, the ratio of the two is 1.0 mL of crosslinking agent per 100 g of solution A, stir in a -5℃ cooling well, the stirring speed is 300 rad / min, and the time is 2 h;

[0059] S8. Centrifuge the mixed system obtained in step S7 to obtain solution B, wherein the centrifugal speed is 6000 rad / min, the time is 5 min, and the temperature is 0℃, and then store solution B in a 5℃ refrigerator;

[0060] S9. In Figure 3In the microfluidic chip shown, the cooled solution B is pumped into the core channel 100 at a pushing speed of 300 μL / min, and the mixed suspension II is pumped into the sheath channel 200 at a pushing speed of 350 μL / min, and they are jointly sprayed from the outlet of the mixing channel 300 into the mixed aqueous solution III for solidification; the solidified material is collected by a roller, and the rotation speed of the roller is 10 rpm;

[0061] S10. The solidified material of step S9 is placed into ultrapure water for washing until the residual acid solution is removed;

[0062] S11. The washed material is frozen in liquid nitrogen, and freeze-dried for 3 h to obtain the fluid power generation fiber.

[0063] The SEM image of the fluid power generation fiber obtained in this example is shown in Figures 1-2 ; and the structural schematic diagram of the chip used is shown in Figure 3 .

[0064] Example 2

[0065] In this example, a fluid power generation fiber is prepared, and the difference from the preparation process of Example 1 is as follows:

[0066] (1) In step S4, 96 g of the mixed aqueous solution I (solvent) and 4 g of cotton linter (natural cellulose) are respectively placed in a -70°C freezer for 2 h;

[0067] (2) In step S7, the addition ratio of the crosslinking agent epichlorohydrin is 1.5 mL of crosslinking agent per 100 g of solution A;

[0068] (3) In step S9, the pushing speed of the cooled solution B is 350 μL / min; and the pushing speed of the mixed suspension II is 400 μL / min.

[0069] The SEM image of the fluid power generation fiber obtained in this example is shown in Figure 6 .

[0070] Example 3

[0071] In this example, a fluid power generation fiber is prepared, and the difference from the preparation process of Example 1 is as follows:

[0072] (1) In step S2, 99 g of the mixed aqueous solution I and 1 g of carbon black nanoparticles are mixed, and ball-milled at 500 rpm for 30 min to obtain the mixed suspension II;

[0073] (2) In step S9, the pushing speed of the cooled solution B is 350 μL / min; and the pushing speed of the mixed suspension II is 400 μL / min.

[0074] The SEM image of the fluid power generation fiber obtained in this example is shown inFigure 7 SEM images of the regenerated fibers obtained in the comparative example are shown in FIG. 6.

[0075] Comparative Example 1

[0076] The comparative example prepared a regenerated fiber, which was different from Example 1 in that:

[0077] (1) In step S9, the cooled solution B was pumped into the core channel 100 at a pushing speed of 200 μL / min, sprayed out of the outlet of the mixing channel 300, and solidified in the mixed aqueous solution III; no solution was injected into the sheath channel 200.

[0078] (2) Before step S10, the material solidified after step S9 was immediately immersed in the mixed suspension II for 10 min, and then step S10 was performed.

[0079] SEM images of the regenerated fibers obtained in the comparative example are shown in FIG. 6. Figure 8

[0080] Test Example

[0081] The morphology, fluid power generation performance, water transmission rate, and fiber strength of the fibers obtained in Examples 1-3 and Comparative Example 1 were tested. Among them:

[0082] The morphology was tested by means of a scanning electron microscope; on the obtained scanning electron microscope image, particle distribution software was used to count the diameter of the fiber.

[0083] The power generation performance was tested: the electrical performance data were obtained using a Keithley 2400 meter, one end of the dried fluid power generation fiber was immersed in a 0.5 mol / L NaCl solution, the other end was exposed to air, and the two ends were respectively contacted with a test pen coated with ink (to eliminate redox reaction);

[0084] The water transmission rate in the fiber was tested: a fluorescence microscope was used to observe and take pictures, a water solution containing fluorescent particles was dropped on the fiber, and the process and speed of the solution along the axial and radial directions of the fiber were recorded;

[0085] The fiber strength was tested by using a fiber mechanical property tester at a temperature of 25°C and a relative humidity of 65%, and the test rate was 1 mm / min. The fluid power generation fiber and the regenerated fiber with a clamping length of 10 mm were stretched.

[0086] The above test results are as follows:

[0087] The morphology test results are as follows: Figures 1-2 The morphology of the fluid power generation fiber obtained in Example 1 is shown in FIG. 1, the morphology of the fluid power generation fiber obtained in Example 2 is shown in FIG. 2, and the morphology of the fluid power generation fiber obtained in Example 3 is shown in FIG. 3. Figure 6 The morphology of the fluid power generation fiber obtained in Example 1 is shown in FIG. 1, the morphology of the fluid power generation fiber obtained in Example 2 is shown in FIG. 2, and the morphology of the fluid power generation fiber obtained in Example 3 is shown in FIG. 3. Figure 7 ​The morphology of the regenerated fiber obtained from Comparative Example 1 is shown in Figure 8 The above SEM image shows that the fluid power generation fiber obtained according to the preparation method provided by the present application is in the form of an elongated filament with the outer layer wrapped with carbon black nanoparticles, as shown in Figure 2 The fiber has two components with different morphological structures and chemical compositions in the direction perpendicular to the extension direction of the fiber, as shown in Figure 1 、 6 The diameters of the fluid power generation fibers of Examples 1 to 3 are 265 μm, 310 μm and 245 μm respectively, and each of the fibers comprises a porous network-like cellulose sponge layer in the center and an edge part formed by the accumulation of carbon black nanoparticles on the outer layer. The average pore size of the center part is larger than that of the edge part. The diameter of the regenerated fiber obtained from Comparative Example 1 is larger, as shown in Figure 8 The diameter is 350 μm. The pore size distribution of the cellulose layer in the generated material is uniform, and there is no interweaving area of carbon black and cellulose, which limits the electrical properties of the regenerated fiber and its application in the field of power supply for small electronic devices.

[0088] The test results of the power generation performance are shown in Table 1.

[0089] Table 1 Electrical properties of the fibers

[0090]

[0091] The test results of the fiber strength are shown in the graph of Figure 9 The strength ranges from 17.62 MPa to 26.78 MPa.

[0092] The test results of the water transmission rate in the fibers are shown in Table 2.

[0093] Table 2 Water transmission rate in the fibers

[0094]

[0095]

[0096] The test results of the water transmission performance of the fluid power generation fiber obtained from Example 1 are shown in Figure 5

[0097] ​As can be seen from Table 2, the fluid power generation fiber prepared by the present application has a central axial water transmission rate of 2-5 mm / s, an edge axial water transmission rate of 0.2-0.4 mm / s, and a radial water transmission rate of 0.1-0.4 mm / s. It can be seen that after one end of the fluid power generation fiber prepared by the present application is immersed in a fluid, the fluid can not only be transmitted in the axial direction of the fiber, but also diffuse in the radial direction during the transmission. The negatively charged cellulose channel can fully promote the ionization of the fluid water molecules, and the overlapping double electron layer only allows positively charged ions to pass through. The ions are continuously rubbed with the outer carbon black nanoparticles during the transmission to induce charge separation. The good hydrophilicity of cellulose promotes the rapid transmission of water along the fiber axis with positive ions, thereby forming a flow current in the axial direction of the fiber. The directional movement of the ions forms a transient and stable potential difference between the two ends of the fiber, realizing fluid power generation. The regenerated fiber prepared in Comparative Example 1 has a larger diameter and uniform internal pores, so the liquid is only transmitted along the axial direction of the fiber. The larger liquid flux slows down the liquid transmission speed, and the fluid power generation performance is reduced.

[0098] Application Example

[0099] The fluid power generation fiber prepared in Example 1 is connected in series with an electrically conductive adhesive and a wire and then connected to an LED display screen to power a small electronic device. The electrical signal test data are shown in Table 2. Figure 10 The results show that the fluid power generation fiber provided by the present application has excellent fluid power generation performance. When the number of series connection is six, the open circuit voltage and short circuit current are 3.12 V and 3.13 μA, respectively, which can power a commercial LED display screen.

[0100] In comparison, the fluid power generation performance of the regenerated fiber obtained in Comparative Example 1 is inferior to that of the fluid power generation fiber provided by the present application under the same test conditions (Table 1). It is illustrated that the fluid power generation fiber provided by the present application is more suitable for being used as a continuous power generation material for utilizing the interaction between liquid and fiber due to its special structure, and has a broad application prospect in the field of powering small electronic devices.

[0101] The above detailed description of the fluid power generation fiber with a two-phase gradient structure, the preparation method and the application in the reference examples is illustrative rather than limiting, and a number of examples can be listed within the defined range. Therefore, the changes and modifications within the overall concept of the present application shall be within the protection scope of the present application.

Claims

1. A method of making a fluid power generation fiber having a two-phase gradient structure, characterized by, The preparation method comprises the following steps: S1. preparing a mixed aqueous solution I, which is a mixed aqueous solution of inorganic base and urea; S2. preparing a mixed suspension II, which is a mixed suspension obtained after carbon black nanoparticles are dispersed in the mixed aqueous solution I and then ball milled; S3. preparing a mixed aqueous solution III, which is a mixed aqueous solution of inorganic acid and metal salt of the inorganic acid; S4. dissolving a fiber raw material in the mixed aqueous solution I under cooling condition, and obtaining solution A after centrifugal defoaming; S5. adding a crosslinking agent to the solution A, and obtaining solution B after cooling reaction and centrifugal defoaming; S6. pumping the solution B and the mixed suspension II into a core layer channel and a sheath layer channel in a microfluidic chip respectively, and then collecting the effluent in the mixed aqueous solution III, and obtaining the fluid power generation fiber with a two-phase gradient structure through centrifugal washing and drying.

2. The production method according to claim 1, characterized by, The inorganic base is at least one of lithium hydroxide, sodium hydroxide and potassium hydroxide; the mass percentage concentrations of the inorganic base and urea in the mixed aqueous solution I are 7-15% and 3-30% respectively; and the mass percentage concentration of the carbon black nanoparticles in the mixed suspension II is 1-2%.

3. The preparation method according to claim 1, characterized in that, In step S3, the inorganic acid is sulfuric acid; the metal salt of the inorganic acid is sodium sulfate; and the mass percentage concentrations of the inorganic acid and the metal salt of the inorganic acid in the mixed aqueous solution III are 5-10% and 1-5.5% respectively.

4. The production method according to claim 1, characterized by, In step S4, the fiber raw material is at least one of cellulose and cotton linters; and the mass percentage concentration of the fiber raw material in the mixed aqueous solution I is 3.0-5.0 wt%.

5. The method of claim 1, wherein, In step S5, the ratio of the solution A to the crosslinking agent is 100 g:(1.0-2.0) ml; and the crosslinking agent is epichlorohydrin.

6. A fluid power generation fiber having a two-phase gradient structure, characterized by, The fluid power generation fiber comprises a porous network-like cellulose sponge layer in the core and a carbon black nanoparticle accumulation layer outside the core; the cellulose sponge layer has micrometer-sized pores which decrease from the center to the edge; and the carbon black nanoparticle accumulation layer has nanometer-sized pores.

7. The fluid power generating fiber of claim 6, wherein, The diameter of the fluid power generation fiber is 150-350 μm.

8. The fluid power generating fiber of claim 6, wherein, The fluid power generation fiber has a central axial fluid transmission rate of 2-5 mm / s, an edge axial fluid transmission rate of 0.2-0.4 mm / s and a radial fluid transmission rate of 0.1-0.4 mm / s.

9. The fluid power generating fiber of claim 6, wherein, The fluid power generation fiber can generate electricity in a fluid with ionization property.

10. Use of the fluid power generation fiber with a two-phase gradient structure according to any one of claims 6-9 as a fluid power generation material.

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