A nanocellulose-based piezoelectric nanogenerator and its manufacturing method

Abstract

The present invention provides a nanocellulose-based piezoelectric nanogenerator and a manufacturing method thereof. The method includes the following steps: Step 1, uniformly mix a CNF dispersion with a mass percentage of 0.8% - 1.2% and an MXene colloidal dispersion with a mass percentage of 3% - 6% to obtain a mixed system A. Freeze-dry the mixed system A to obtain a composite aerogel, and coat polydimethylsiloxane on the upper and lower surfaces of the composite aerogel respectively to obtain a mixed system B; Step 2, cure the mixed system B to obtain the core component of the nanocellulose-based piezoelectric nanogenerator, and attach aluminum foils to the upper and lower surfaces of the core component respectively to obtain the nanocellulose-based piezoelectric nanogenerator. Using the CNF / MXene composite aerogel as the piezoelectric layer, PDMS as the encapsulation layer, and aluminum foil as the conductive electrode, a flexible piezoelectric nanogenerator with high piezoelectricity is obtained.

Description

Technical Field

[0001] The present invention belongs to the field of nanofiber materials and relates to a nanocellulose-based piezoelectric nanogenerator and a manufacturing method thereof. Background Art

[0002] In recent years, due to the development of science and technology, portable and wearable devices have gradually become an indispensable part of daily life. However, the battery life problem of these electronic devices is also very obvious. The main reason is that the batteries used for power supply need to be repeatedly charged or regularly replaced. In addition, the treatment of waste batteries is also an urgent problem to be solved. The leakage of electrolytes and non-degradable battery materials will cause serious environmental pollution and is not conducive to the sustainable development of human society.

[0003] The use of piezoelectric nanogenerators can achieve self-power supply for small electronic devices, providing the possibility for the development of a new generation of environmentally friendly long-endurance electronic products. However, artificial piezoelectric materials commonly used for mechanical energy harvesting consume a large amount of energy during the synthesis process and also cause certain pollution to the environment. Therefore, it is particularly important to develop an economical and environmentally friendly piezoelectric nanogenerator. Cellulose is the most abundant organic matter in nature and can be directly extracted from plant fibers. Due to the special structure of its polymer chains, cellulose can not only achieve biodegradation, but its unique central asymmetric structure endows it with certain piezoelectricity.

[0004] However, compared with artificially synthesized piezoelectric polymers, the piezoelectric performance of natural cellulose is not outstanding. At present, some scientific and technological workers have used one-dimensional material multi-walled carbon nanotubes (MWCNTs) to enhance the piezoelectricity of nanocellulose. Through mechanical stretching, the directional arrangement of MWCNTs and cellulose chains is realized, thereby promoting the improvement of the piezoelectric constant. However, the directional induction range of one-dimensional materials is weak and it is difficult to generate local polarization. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention proposes a nanocellulose-based piezoelectric nanogenerator and a manufacturing method thereof. Using CNF / MXene composite aerogel as the piezoelectric layer, PDMS as the encapsulation layer, and aluminum foil as the conductive electrode, a flexible piezoelectric nanogenerator with high piezoelectricity is obtained.

[0006] The present invention is realized through the following technical solutions:

[0007] A manufacturing method of a nanocellulose-based piezoelectric nanogenerator includes the following steps:

[0008] Step 1, mix a CNF dispersion with a mass percentage of 0.8% to 1.2% and an MXene colloidal dispersion with a mass percentage of 3% to 6% evenly to obtain a mixed system A. Freeze-dry the mixed system A to obtain a composite aerogel, and coat polydimethylsiloxane on the upper and lower surfaces of the composite aerogel respectively to obtain a mixed system B;

[0009] Step 2, cure the mixed system B to obtain the core component of the nanocellulose-based piezoelectric nanogenerator, and attach aluminum foils to the upper and lower surfaces of the core component respectively to obtain the nanocellulose-based piezoelectric nanogenerator.

[0010] Preferably, in Step 1, the mass ratio of the CNF dispersion to the MXene colloidal dispersion is (18.5 to 20.5):(1.7 to 6.7).

[0011] Preferably, in Step 1, stir the CNF dispersion and the MXene colloidal dispersion at 25 to 35 °C for 20 to 60 min to obtain the mixed system A.

[0012] Preferably, in Step 1, mix the CNF dispersion and the MXene colloidal dispersion evenly in a square container to obtain the mixed system A.

[0013] Preferably, in Step 1, freeze-dry the mixed system A at -50 to -45 °C for 24 to 48 h to obtain the composite aerogel.

[0014] Preferably, the polydimethylsiloxane in Step 1 is obtained as follows:

[0015] Stir a prepolymer and a curing agent at a mass ratio of 10:1 for 10 to 30 min, and then refrigerate at 3 to 10 °C for 10 to 14 h to obtain the polydimethylsiloxane.

[0016] Preferably, in Step 1, coat polydimethylsiloxane with a thickness of 50 to 100 μm on both the upper and lower surfaces of the composite aerogel to obtain the mixed system B.

[0017] Preferably, in Step 2, cure the mixed system B at 80 to 100 °C.

[0018] Preferably, in Step 2, cure the mixed system B at the above temperature for 3 to 4 h.

[0019] A nanocellulose-based piezoelectric nanogenerator obtained by the manufacturing method of the nanocellulose-based piezoelectric nanogenerator described in any one of the above.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] A method for fabricating a nanocellulose-based piezoelectric nanogenerator of the present invention uses highly crystalline cellulose nanofibers (CNF) as the piezoelectric component and also serves as the substrate. Two-dimensional titanium carbide (MXene) colloids are introduced into the cellulose nanofibers for induction, and are uniformly mixed in the form of a dispersion and then freeze-dried to obtain a CNF / MXene composite aerogel. On the one hand, the microstructure of the composite material is adjusted to make the cellulose arrange more orderly, improving the piezoelectric performance; on the other hand, group interactions can be used to enhance local polarization, thereby further enhancing the piezoelectric effect. Then, PDMS is used as the encapsulation layer to make the output of the piezoelectric nanogenerator stable. Aluminum foil is used as the conductive electrode. When in use, two wires can be directly connected to the aluminum foil to obtain a flexible piezoelectric nanogenerator with high piezoelectricity. Titanium carbide nanosheets with strongly electronegative functional groups on the surface are used as templates to induce local polarization effects in the cellulose nanofibers and improve the regularity of the arrangement of cellulose in the aerogel. The present invention uses an environmentally friendly substrate and has a simple manufacturing process, and good piezoelectric output performance can be obtained without any high-voltage polarization treatment. Description of the Drawings

[0022] Figure 1 is a physical diagram of the core component of the piezoelectric nanogenerator of the present invention.

[0023] Figure 2 is a physical diagram of the piezoelectric nanogenerator of the present invention.

[0024] Figure 3 is a graph showing the charging of a 10 μF capacitor by the piezoelectric nanogenerator of the present invention.

[0025] Figure 4 is a physical diagram of the piezoelectric nanogenerator of the present invention lighting a blue light-emitting diode. Detailed Embodiments

[0026] The following further describes the present invention in detail with specific embodiments, which are explanations of the present invention rather than limitations.

[0027] A method for fabricating a nanocellulose-based piezoelectric nanogenerator of the present invention specifically includes the following steps:

[0028] Step 1: Respectively take 18.50 - 20.50 parts by mass of a CNF dispersion with a mass percentage of 0.8% - 1.2% and 1.70 - 6.70 parts by mass of an MXene colloidal dispersion with a mass percentage of 3% - 6%. Both dispersions are obtained by dispersing the corresponding substances in deionized water. After mixing, use a magnetic stirrer with a heating mantle for constant temperature heating to stir at a temperature of 25 - 35°C for 20 - 60 minutes to achieve the purpose of mixing evenly. After taking it out, pour it into a square reaction dish made of plastic material and freeze-dry it at a temperature of -50 - -45°C for 24 - 48 hours to obtain the CNF / MXene composite aerogel;

[0029] Step 2: Mix the prepolymer SYLGUARD-184A and the curing agent SYLGUARD-184B according to a mass ratio of 10:1, stir for 10 - 30 minutes to achieve uniformity, then put it into the refrigerator and refrigerate it at a temperature of 3°C - 10°C for 10 - 14 hours to remove bubbles in this way to obtain polydimethylsiloxane (PDMS). Then coat it on the upper and lower surfaces of the CNF / MXene composite aerogel, with a thickness of 50 - 100 μm each, and cure it at 80 - 100°C for 3 - 4 hours. The curing of PDMS makes the output of the piezoelectric nanogenerator stable, and the core component of the nanocellulose-based piezoelectric nanogenerator is prepared;

[0030] Step 3: Attach aluminum foil electrodes to the upper and lower surfaces of the core component respectively. The area of the aluminum foil electrodes shall not be larger than the upper and lower surfaces of the core component of the piezoelectric nanogenerator, and two wires are directly connected to the aluminum foil to obtain the piezoelectric nanogenerator.

[0031] Example 1:

[0032] A manufacturing method of a nanocellulose-based piezoelectric nanogenerator, including the following steps:

[0033] Step 1: Take 18.50 parts by mass of a CNF dispersion with a mass percentage of 0.8% and 1.85 parts by mass of an MXene colloidal dispersion with a mass percentage of 3.5%. After mixing, use a magnetic stirrer with a heating mantle for constant temperature heating to stir at a temperature of 25°C for 30 minutes to achieve the purpose of mixing evenly. After taking it out, pour it into a square reaction dish made of plastic material and freeze-dry it at -48°C for 24 hours to obtain the CNF / MXene composite aerogel;

[0034] Step 2: Mix the prepolymer SYLGUARD-184A and the curing agent SYLGUARD-184B according to a mass ratio of 10:1, stir evenly for 12 minutes to achieve uniformity, then put it into the refrigerator and refrigerate it at 4°C for 10 hours to remove bubbles, and then coat it on the upper and lower surfaces of the CNF / MXene composite aerogel, and cure it at 85°C for 4 hours to prepare the core component of the piezoelectric nanogenerator;

[0035] Step 3: Attach aluminum foil electrodes to the upper and lower surfaces of the core component respectively. The area of the aluminum foil electrodes shall not be larger than the upper and lower surfaces of the core component of the piezoelectric nanogenerator. Connect two wires directly to the aluminum foil, and then the piezoelectric nanogenerator is obtained.

[0036] The open-circuit voltage of the piezoelectric nanogenerator fabricated in this example is 19.4 V, and the short-circuit current is 141.8 nA.

[0037] Example 2:

[0038] A method for fabricating a nanocellulose-based piezoelectric nanogenerator includes the following steps:

[0039] 1) Take 19.30 parts by mass of a CNF dispersion with a mass percentage of 1.0% and 3.76 parts by mass of a MXene colloidal dispersion with a mass percentage of 4.2%. After mixing, stir with a thermostatic heating magnetic stirrer at a temperature of 28 °C for 42 min. Take it out and pour it into a square reaction dish made of plastic, and freeze-dry at -47 °C for 36 h to obtain the CNF / MXene composite aerogel.

[0040] 2) Mix the prepolymer SYLGUARD-184A and the curing agent SYLGUARD-184B in a mass ratio of 10:1, stir evenly for 20 min, then put it into the refrigerator, refrigerate at 6 °C for 12 h to remove bubbles, and then coat it on the upper and lower surfaces of the CNF / MXene composite aerogel, and cure at 95 °C for 3.5 h to obtain the core component of the piezoelectric nanogenerator.

[0041] 3) Attach aluminum foil electrodes to the upper and lower surfaces of the core component respectively. The area of the aluminum foil electrodes shall not be larger than the upper and lower surfaces of the core component of the piezoelectric nanogenerator. Connect two wires directly to the aluminum foil, and then the piezoelectric nanogenerator is obtained.

[0042] The open-circuit voltage of the piezoelectric nanogenerator fabricated in this example is 27.3 V, and the short-circuit current is 284.1 nA.

[0043] Example 3:

[0044] A method for fabricating a nanocellulose-based piezoelectric nanogenerator includes the following steps:

[0045] 1) Take 20.25 parts by mass of a CNF dispersion with a mass percentage of 1.2% and 6.08 parts by mass of a MXene colloidal dispersion with a mass percentage of 5.8%. After mixing, stir with a thermostatic heating magnetic stirrer at a temperature of 32 °C for 55 min. Take it out and pour it into a square reaction dish made of plastic, and freeze-dry at -45 °C for 48 h to obtain the CNF / MXene composite aerogel.

[0046] 2) Mix the prepolymer SYLGUARD-184A and the curing agent SYLGUARD-184B in a mass ratio of 10:1, stir evenly for 25 min, then put it into the refrigerator, refrigerate at 8 °C for 14 h to remove bubbles, and then coat it on the upper and lower surfaces of the CNF / MXene composite aerogel, and cure at 100 °C for 3.0 h to obtain the core component of the piezoelectric nanogenerator;

[0047] 3) Attach aluminum foil electrodes to the upper and lower surfaces of the core component respectively. The area of the aluminum foil electrode shall not be larger than the upper and lower surfaces of the core component of the piezoelectric nanogenerator, and two wires are directly connected to the aluminum foil, thus obtaining the piezoelectric nanogenerator.

[0048] The open-circuit voltage of the piezoelectric nanogenerator fabricated in this example is 23.5 V, and the short-circuit current is 201.6 nA.

[0049] Figure 1 is a physical diagram of the core component of the fabricated piezoelectric nanogenerator. From Figure 1 it can be seen that the piezoelectric nanogenerator has the characteristics of flexibility and bendability.

[0050] Figure 2 is a physical diagram of the fabricated piezoelectric nanogenerator. From Figure 2 it can be seen that the size of the piezoelectric nanogenerator is approximately 3 cm × 2.5 cm.

[0051] Figure 3 is a curve graph of the piezoelectric nanogenerator charging a 10 μF capacitor. From Figure 3 the circuit diagram, it can be seen that four diodes are combined into a bridge rectifier, which can convert alternating current into direct current. When the piezoelectric nanogenerator is subjected to cyclic impact, the bridge rectifier charges the capacitor (10 μF). After running for about 50 s, the capacitor is charged to 1.07 V, demonstrating the energy harvesting and conversion ability of the piezoelectric nanogenerator.

[0052] Figure 4 is a physical diagram of the piezoelectric nanogenerator powering a small light-emitting diode lamp. From Figure 4 it can be seen that two wires are directly connected to the light-emitting diode. When no pressure and frequency are applied to the linear motor, the light-emitting diode does not light up; when a certain pressure and frequency are applied to the linear motor, the motor can instantaneously impact the piezoelectric nanogenerator, and the circuit is conducted at the moment of impact, and the light-emitting diode is lit. The piezoelectric nanogenerator fabricated by this method can directly light up 8 blue light-emitting diodes (about 3.2 V), demonstrating the feasibility of its use as a power source.

Claims

1. A method for fabricating a nanocellulose-based piezoelectric nanogenerator, characterized in that, It includes the following steps: Step 1: Stir a CNF dispersion with a mass percentage of 0.8% - 1.2% and an MXene colloidal dispersion with a mass percentage of 3% - 6% at 25 - 35 °C for 20 - 60 min. The mass ratio of the CNF dispersion to the MXene colloidal dispersion is (18.5 - 20.5):(1.7 - 6.7) to obtain a mixed system A. Freeze-dry the mixed system A at -50 - -45 °C for 24 - 48 h to obtain a composite aerogel. Coat polydimethylsiloxane on the upper and lower surfaces of the composite aerogel respectively to obtain a mixed system B; Step 2: Cure the mixed system B at 80 - 100 °C for 3 - 4 h to obtain the core component of the nanocellulose-based piezoelectric nanogenerator. Stick aluminum foils on the upper and lower surfaces of the core component respectively to obtain the nanocellulose-based piezoelectric nanogenerator.

2. The manufacturing method of the nanocellulose-based piezoelectric nanogenerator according to claim 1, characterized in that The polydimethylsiloxane described in Step 1 is obtained according to the following process: Stir the prepolymer and the curing agent at a mass ratio of 10:1 for 10 - 30 min, and then refrigerate at 3 - 10 °C for 10 - 14 h to obtain polydimethylsiloxane.

3. The manufacturing method of the nanocellulose-based piezoelectric nanogenerator according to claim 1, characterized in that, In Step 1, coat polydimethylsiloxane with a thickness of 50 - 100 μm on both the upper and lower surfaces of the composite aerogel to obtain a mixed system B.

4. A nanocellulose-based piezoelectric nanogenerator obtained by the manufacturing method of the nanocellulose-based piezoelectric nanogenerator according to any one of claims 1 - 3.

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