Preparation method of all-biomass carbon-based all-vanadium redox flow battery electrode

Abstract

The application discloses a preparation method of a full-biomass carbon-based electrode of a full-vanadium liquid flow battery, and relates to the field of electrochemical energy storage liquid flow batteries.The biomass raw materials such as bamboo and wood are ground into powder, and are taken according to a certain mass ratio with sodium carboxymethyl cellulose; a proper amount of deionized water is added to fully stir to obtain a uniform slurry; then the slurry is poured into a mold to be shaped to obtain a biomass-based precursor; finally, the biomass-based precursor is calcined in a high-temperature tube furnace to obtain a full-biomass carbon-based electrode material.Compared with a commercial carbon electrode, the electrode has a significantly improved hydrophilicity, and has a multi-dimensional coexisting structure inside the electrode, so that more flow channels are provided for electrolyte, which is beneficial to reducing the migration distance of vanadium ions to active sites.The design method is not affected by the uneven batches of biomass raw materials, and is suitable for commercial large-scale preparation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of all-vanadium redox flow battery energy storage, and particularly relates to a preparation method of a full-biomass carbon-based electrode material and application of the full-biomass carbon-based electrode material in an all-vanadium redox flow battery. BACKGROUND

[0002] At present, the research on electrode materials in all-vanadium redox flow batteries (VRFBs) tends to improve the electrochemical performance of commercial electrode materials such as carbon felt. However, the problem of electrode activity reduction caused by electrode structure and morphology changes due to continuous charge and discharge cycles cannot be ignored, which is also the inherent disadvantage of current commercial electrode materials. In addition, most commercial electrodes are polyacrylonitrile-based fibers, pitch-based fibers and other petroleum-based materials, and the preparation process involves a series of process requirements such as solvent recovery, wastewater treatment and high-temperature treatment, and problems such as fire prevention, poison prevention and equipment selection, and the electrode material recycling process needs to be further explored. The complicated preparation process of electrode materials and additional processing technology are one of the factors affecting the high cost of VRFBs, and the performance degradation and poor durability of electrode materials are also one of the main challenges faced by VRFBs technology. In view of the above problems, it is urgent to develop new electrode materials with green low cost, reasonable structure design, excellent and stable performance, which is helpful for the further commercialization development of VRFBs.

[0003] The pore structure and electrochemical activity of the electrode affect the electrochemical performance of VRFBs, such as efficiency, life, capacity and power. Biomass carbon materials have high electrical conductivity, large specific surface area and rich heteroatoms, and are ideal electrode materials for VRFBs. Carbon electrode materials derived from cotton, silk fabric, wood and the like have been successfully proved to be suitable for VRFBs. However, the research on biomass carbon-based electrodes is mostly limited to the natural form of biomass raw materials, and there are obvious challenges in the scaled-up preparation, so it is necessary to further explore new design methods of biomass carbon-based electrode materials.

[0004] Document (Yang Y, Sun X, Cheng Z, et al. Functionalized well-aligned channels derived from wood as a convection-enhanced electrode for aqueous flow batteries [J]. ACS Applied Energy Materials, 2020, 3(7): 6249-6257.) discloses a functionalized wood-derived wood carbon electrode and is applied to a vanadium redox flow battery. The natural microporous structure of wood is used to realize the flow of electrolyte, and the content of functional groups is increased and the hydrophilicity of the material electrode is improved by nitric acid treatment. The above document provides a preparation method of a full biomass carbon electrode material in a vanadium redox flow battery, but the scheme is limited by the type and natural size of wood and the uneven internal microporous structure of the material, and it is difficult to realize large-scale preparation. SUMMARY

[0005] In order to overcome the deficiencies in the prior art, the present application provides a preparation method of a full biomass carbon vanadium redox flow battery electrode and its application.

[0006] As an aspect of the present application, the present application provides a preparation method of a full biomass carbon vanadium redox flow battery electrode, comprising the following steps:

[0007] (S1) The biomass raw material is cut into small pieces, washed with deionized water and anhydrous ethanol, and then naturally dried, and then placed in a 60-80℃ oven for drying for standby;

[0008] (S2) The dry and clean biomass raw material is placed in a crusher and crushed to powder, and sieved;

[0009] (S3) The biomass powder and sodium carboxymethyl cellulose are weighed according to a certain mass ratio, and an appropriate amount of deionized water is added and stirred to obtain a uniform slurry;

[0010] (S4) Pour the slurry into a mold to shape, thereby obtaining a biomass-based precursor;

[0011] (S5) The biomass-based precursor is placed in a high-temperature tube furnace and heated to 600-1200℃ under N2 atmosphere and kept for 1-3h to obtain a full biomass carbon-based electrode material.

[0012] Preferably, the biomass raw material of step (S1) includes bamboo and wood.

[0013] Preferably, the sieving treatment of step (S2) has a mesh size of 40-200 mesh.

[0014] Preferably, the mass ratio of the biomass powder to sodium carboxymethyl cellulose in step (S3) is 2:1-8:1.

[0015] Preferably, the shaping method of the slurry in step (S4) comprises drying and freeze-drying. The drying condition is 60-80℃ for 24-36h, and the freeze-drying condition is -60--20℃ for 36-72h.

[0016] Further preferably, the heating temperature in step (S5) is 1100℃, and the heating time is 2h.

[0017] As another aspect of the present application, the present application provides a full-biomass carbon full-vanadium flow battery electrode obtained by the above preparation method.

[0018] As still another aspect of the present application, the present application provides an application of a full-biomass carbon full-vanadium flow battery electrode.

[0019] Specifically, a full-biomass carbon electrode is used as a working electrode, a platinum electrode is used as a counter electrode, and a Hg / Hg2SO4 electrode is used as a reference electrode to construct a full-vanadium flow battery three-electrode system for electrochemical performance testing. The electrolyte composition is 0.1mol / L VOSO4 and 2.0mol / L H2SO4. A full-biomass carbon electrode is used as a positive electrode, a Nafion 212 membrane is used as an ion exchange membrane, and the electrolyte composition is 1.5mol / L VOSO4 and 3.0mol / L H2SO4 to assemble a full-vanadium flow battery for rate testing under the condition of 50-360mA / cm 2 .

[0020] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0021] (1) Bamboo and wood are selected as raw materials to design a biomass carbon-based electrode directly applied to a full-vanadium flow battery. Bamboo is the fastest-growing plant in the world and is a sustainable renewable biomass resource, with the characteristics of short growth cycle and abundant yield, which can meet the specific supply of large-scale biomass raw materials.

[0022] (2) The present application adopts a bottom-up structural crushing and reconstruction strategy to crush bamboo into bamboo powder, selects sodium carboxymethyl cellulose as a binder to assemble bamboo fibers into a specific specification precursor, and then obtains a biomass carbon-based matrix electrode material with coexisting multi-dimensional structures through one-step carbonization. The electrode prepared by this method has better hydrophilicity than polyacrylonitrile-based carbon felt, and the internal structure of the electrode is beneficial to the rapid transfer of the electrolyte, reduces the migration distance of vanadium ions to the active sites, and vanadium ions are more easily adsorbed, thereby showing more excellent electrochemical performance. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Cyclic voltammogram of the electrode material obtained for Example 1, Example 2, Example 3, Example 4, Example 5, Example 6, Example 7.

[0024] Figure 2 Cyclic voltammogram of the electrode material obtained for Example 6, Example 8, Example 9.

[0025] Figure 3 Cyclic voltammogram of the electrode material obtained for Example 6, Example 10.

[0026] Figure 4 Cyclic voltammogram of the electrode material obtained for Example 10, Example 11, Example 12.

[0027] Figure 5 Scanning electron microscope image of the electrode material obtained for Example 10.

[0028] Figure 6 Contact angle comparison of commercial carbon felt (a) and the electrode material obtained for Example 10 (b).

[0029] Figure 7 Rate capability comparison of commercial carbon felt (a) and the electrode material obtained for Example 10 (b). DETAILED DESCRIPTION

[0030] In order for the reader to have a better understanding of the present application, the present application will be described in more detail below in conjunction with the accompanying drawings and preferred embodiments, but the scope of protection of the present application is not limited to the following specific embodiments. It should be noted that if the manufacturer of the reagent or instrument is not specified, it is considered to be a conventional product that can be obtained by commercial purchase.

[0031] Example 1

[0032] The bamboo powder sieved by an 80-mesh sieve and sodium carboxymethyl cellulose were weighed at a mass ratio of 4:1, 1 g of bamboo powder and 0.25 g of sodium carboxymethyl cellulose, 32 mL of deionized water was added and stirred to obtain a uniform slurry, then poured into a mold, tapped appropriately and left for 10 min to remove bubbles, then placed in a 60°C oven for drying for 12 h, thus obtaining a bamboo-based precursor. Finally, it was placed in a high-temperature tube furnace, dried at 600°C under N2 atmosphere for 2 h, to obtain a full-biomass carbon-based electrode material.

[0033] The electrode material prepared in this example is used as the working electrode, a platinum electrode is used as the counter electrode, and a Hg / HgSO4 electrode is used as the reference electrode to construct a three-electrode unit system of the all-vanadium redox flow battery. The electrolyte is composed of 0.1 mol / L VOSO4 and 2.0 mol / L H2SO4. The cyclic voltammetry curve of the three-electrode system is as shown in Figure 1 .

[0034] Example 2

[0035] The bamboo powder sieved by an 80-mesh sieve is mixed with carboxymethyl cellulose sodium according to a mass ratio of 4:1, 1 g of the bamboo powder and 0.25 g of the carboxymethyl cellulose sodium are weighed, 32 mL of deionized water is added, and the mixture is fully stirred to obtain a uniform slurry, which is then poured into a mold, tapped appropriately, and left to stand for 10 min to remove bubbles, and then placed in a 60°C oven for drying for 12 h, thereby obtaining a bamboo-based precursor. Finally, the bamboo-based precursor is placed in a high-temperature tube furnace, dried at 700°C under a N2 atmosphere for 2 h, and a full-biomass carbon-based electrode material is obtained.

[0036] The electrode material prepared in this example is used as the working electrode, a platinum electrode is used as the counter electrode, and a Hg / HgSO4 electrode is used as the reference electrode to construct a three-electrode unit system of the all-vanadium redox flow battery. The electrolyte is composed of 0.1 mol / L VOSO4 and 2.0 mol / L H2SO4. The cyclic voltammetry curve of the three-electrode system is as shown in Figure 1 .

[0037] Example 3

[0038] The bamboo powder sieved by an 80-mesh sieve is mixed with carboxymethyl cellulose sodium according to a mass ratio of 4:1, 1 g of the bamboo powder and 0.25 g of the carboxymethyl cellulose sodium are weighed, 32 mL of deionized water is added, and the mixture is fully stirred to obtain a uniform slurry, which is then poured into a mold, tapped appropriately, and left to stand for 10 min to remove bubbles, and then placed in a 60°C oven for drying for 12 h, thereby obtaining a bamboo-based precursor. Finally, the bamboo-based precursor is placed in a high-temperature tube furnace, dried at 800°C under a N2 atmosphere for 2 h, and a full-biomass carbon-based electrode material is obtained.

[0039] The electrode material prepared in this example is used as the working electrode, a platinum electrode is used as the counter electrode, and a Hg / HgSO4 electrode is used as the reference electrode to construct a three-electrode unit system of the all-vanadium redox flow battery. The electrolyte is composed of 0.1 mol / L VOSO4 and 2.0 mol / L H2SO4. The cyclic voltammetry curve of the three-electrode system is as shown in Figure 1 .

[0040] Example 4

[0041] The bamboo powder treated by 80 mesh sieve and sodium carboxymethyl cellulose were weighed according to the mass ratio of 4:1, 1 g of bamboo powder and 0.25 g of sodium carboxymethyl cellulose were taken, 32 mL of deionized water was added and stirred to obtain a uniform slurry, then the slurry was poured into a mold, tapped appropriately and placed for 10 min to remove bubbles, then placed in a 60°C oven for drying for 12 h, thus obtaining a bamboo-based precursor. Finally, it was placed in a high-temperature tube furnace, dried at 900°C under N2 atmosphere for 2 h, and a full-biomass carbon-based electrode material was obtained.

[0042] The electrode material prepared in this example was used as the working electrode, a platinum electrode was used as the counter electrode, and a Hg / HgSO4 electrode was used as the reference electrode to construct a three-electrode unit system of a vanadium redox flow battery. The electrolyte composition was 0.1 mol / L VOSO4 and 2.0 mol / L H2SO4. The three-electrode system was subjected to cyclic voltammetry test, and the scan rate was set to 10 mV / s. The cyclic voltammogram is shown in Figure 1 .

[0043] Example 5

[0044] The bamboo powder treated by 80 mesh sieve and sodium carboxymethyl cellulose were weighed according to the mass ratio of 4:1, 1 g of bamboo powder and 0.25 g of sodium carboxymethyl cellulose were taken, 32 mL of deionized water was added and stirred to obtain a uniform slurry, then the slurry was poured into a mold, tapped appropriately and placed for 10 min to remove bubbles, then placed in a 60°C oven for drying for 12 h, thus obtaining a bamboo-based precursor. Finally, it was placed in a high-temperature tube furnace, dried at 1000°C under N2 atmosphere for 2 h, and a full-biomass carbon-based electrode material was obtained.

[0045] The electrode material prepared in this example was used as the working electrode, a platinum electrode was used as the counter electrode, and a Hg / HgSO4 electrode was used as the reference electrode to construct a three-electrode unit system of a vanadium redox flow battery. The electrolyte composition was 0.1 mol / L VOSO4 and 2.0 mol / L H2SO4. The three-electrode system was subjected to cyclic voltammetry test, and the scan rate was set to 10 mV / s. The cyclic voltammogram is shown in Figure 1 .

[0046] Example 6

[0047] The bamboo powder treated by 80 mesh sieve and sodium carboxymethyl cellulose were weighed according to the mass ratio of 4:1, 1 g of bamboo powder and 0.25 g of sodium carboxymethyl cellulose were taken, 32 mL of deionized water was added and stirred to obtain a uniform slurry, then the slurry was poured into a mold, tapped appropriately and placed for 10 min to remove bubbles, then placed in a 60°C oven for drying for 12 h, thus obtaining a bamboo-based precursor. Finally, it was placed in a high-temperature tube furnace, dried at 1100°C under N2 atmosphere for 2 h, and a full-biomass carbon-based electrode material was obtained.

[0048] The electrode material prepared in this example is used as the working electrode, a platinum electrode is used as the counter electrode, and a Hg / HgSO4 electrode is used as the reference electrode to construct a three-electrode unit system of the all-vanadium redox flow battery. The electrolyte is composed of 0.1 mol / L VOSO4 and 2.0 mol / L H2SO4. The cyclic voltammetry curve of the three-electrode system is shown in Figure 1 .

[0049] Example 7

[0050] The bamboo powder sieved through an 80-mesh sieve is mixed with carboxymethyl cellulose sodium according to a mass ratio of 4:1, 1 g of the bamboo powder and 0.25 g of the carboxymethyl cellulose sodium are weighed, 32 mL of deionized water is added, and the mixture is stirred to obtain a uniform slurry. Then, the slurry is poured into a mold, tapped appropriately, and left to stand for 10 min to remove bubbles. Subsequently, the slurry is placed in a 60°C oven for drying for 12 h, thereby obtaining a bamboo-based precursor. Finally, the bamboo-based precursor is placed in a high-temperature tube furnace, carbonized at 1200°C under a N2 atmosphere, and kept for 2 h, thereby obtaining a full-biomass carbon-based electrode material.

[0051] The electrode material prepared in this example is used as the working electrode, a platinum electrode is used as the counter electrode, and a Hg / HgSO4 electrode is used as the reference electrode to construct a three-electrode unit system of the all-vanadium redox flow battery. The electrolyte is composed of 0.1 mol / L VOSO4 and 2.0 mol / L H2SO4. The cyclic voltammetry curve of the three-electrode system is shown in Figure 1 .

[0052] Figure 1 The cyclic voltammetry curves of the electrode materials obtained in Examples 1, 2, 3, 4, 5, 6, and 7 show that the full-biomass carbon-based electrode obtained by carbonizing the bamboo-based precursor at 1100°C has the largest oxidation peak current (89.2 mA) and a smaller peak potential difference (0.53 V), indicating that it has the best electrochemical performance. This indicates that 1100°C is the optimal carbonization temperature.

[0053] Example 8

[0054] The bamboo powder sieved through an 80-mesh sieve is mixed with carboxymethyl cellulose sodium according to a mass ratio of 4:1, 1 g of the bamboo powder and 0.25 g of the carboxymethyl cellulose sodium are weighed, 32 mL of deionized water is added, and the mixture is stirred to obtain a uniform slurry. Then, the slurry is poured into a mold, tapped appropriately, and left to stand for 10 min to remove bubbles. Subsequently, the slurry is placed in a 60°C oven for drying for 12 h, thereby obtaining a bamboo-based precursor. Finally, the bamboo-based precursor is placed in a high-temperature tube furnace, carbonized at 1100°C under a N2 atmosphere, and kept for 1 h, thereby obtaining a full-biomass carbon-based electrode material.

[0055] The electrode material prepared in this example is used as a working electrode, a platinum electrode is used as a counter electrode, and a Hg / HgSO4 electrode is used as a reference electrode to construct a three-electrode unit system of a vanadium redox flow battery. The electrolyte is composed of 0.1 mol / L VOSO4 and 2.0 mol / L H2SO4. The cyclic voltammetry curve of the three-electrode system is shown in Figure 2 .

[0056] Example 9

[0057] The 80-mesh sieve-sifted bamboo powder and sodium carboxymethyl cellulose are weighed according to a mass ratio of 4:1, 1 g of the bamboo powder and 0.25 g of the sodium carboxymethyl cellulose are taken, 32 mL of deionized water is added, and the mixture is fully stirred to obtain a uniform slurry, which is then poured into a mold, tapped appropriately, and left to stand for 10 min to remove bubbles, and then placed in a 60°C oven for drying for 12 h, thereby obtaining a bamboo-based precursor. Finally, the bamboo-based precursor is placed in a high-temperature tube furnace, carbonized at 1100°C under a N2 atmosphere, and kept for 3 h, thereby obtaining a full-biomass carbon-based electrode material.

[0058] The electrode material prepared in this example is used as a working electrode, a platinum electrode is used as a counter electrode, and a Hg / HgSO4 electrode is used as a reference electrode to construct a three-electrode unit system of a vanadium redox flow battery. The electrolyte is composed of 0.1 mol / L VOSO4 and 2.0 mol / L H2SO4. The cyclic voltammetry curve of the three-electrode system is shown in Figure 2 .

[0059] Figure 2 The cyclic voltammetry curves of the electrode materials obtained in Examples 6, 8, and 9 show that the full-biomass carbon-based electrode obtained by carbonizing the bamboo-based precursor at 1100°C for 120 min has the largest peak current (89.2 mA) and a smaller peak potential difference (0.53 V), indicating that it has the best electrochemical performance. This shows that 120 min is the optimal carbonization holding time.

[0060] Example 10

[0061] The 80-mesh sieve-sifted bamboo powder and sodium carboxymethyl cellulose are weighed according to a mass ratio of 4:1, 1 g of the bamboo powder and 0.25 g of the sodium carboxymethyl cellulose are taken, 32 mL of deionized water is added, and the mixture is fully stirred to obtain a uniform slurry, which is then poured into a mold, tapped appropriately, and left to stand for 10 min to remove bubbles, and then rapidly frozen in liquid nitrogen and placed in a freeze dryer for 48 h, thereby obtaining a bamboo-based precursor. Finally, the bamboo-based precursor is placed in a high-temperature tube furnace, carbonized at 1100°C under a N2 atmosphere, and kept for 2 h, thereby obtaining a full-biomass carbon-based electrode material.

[0062] The electrode material prepared in this example was used as the working electrode, platinum electrode as the counter electrode, and Hg / HgSO4 electrode as the reference electrode to construct a three-electrode unit system of the all-vanadium redox flow battery. The electrolyte composition was 0.1 mol / L VOSO4 and 2.0 mol / L H2SO4. The cyclic voltammetry test was performed on the three-electrode system, and the scan rate was set to 10 mV / s. The cyclic voltammogram is shown in Figure 3 .

[0063] Figure 3 The cyclic voltammograms of the electrode materials obtained in Example 6 and Example 10 showed that the all-biomass carbon-based electrode obtained by carbonizing the freeze-dried shaped bamboo-based precursor had the largest oxidation peak current (129.3 mA) and smaller peak potential difference (0.50 V), indicating that it had the best electrochemical performance. This shows that freeze-drying shaping is a better precursor shaping method.

[0064] The electron microscope image of the electrode prepared in Example 10 is shown in Figure 5 . The electrode has a multi-dimensional coexisting structure with bamboo carbon fibers and two-dimensional carbon nanosheets, which can provide more abundant channels and larger redox reaction area for electrolyte flow.

[0065] The contact angle test results of the electrode prepared in Example 10 and the commercial carbon felt are shown in Figure 6 . The all-biomass-based electrode showed excellent hydrophilicity, and the contact angle with water was 0°. However, the commercial CF had obvious hydrophobicity, and the contact angle reached 130.84°.

[0066] The modified electrode material prepared in this example was used as the positive electrode, Nafion 212 was used as the separator, and the electrolyte was 1.5 mol / L VOSO4 and 3.0 mol / L H2SO4 to assemble the all-vanadium redox flow battery. The rate test of the battery was performed at a current density of 50-360 mA / cm 2 . As a comparison, the commercial carbon felt was tested under the same conditions, and the results are shown in Figure 7 .

[0067] The battery based on this example showed higher energy efficiency than the control battery under all test conditions, and the EE increased by 8.96% at 250 mA·cm -2 . This shows that the BCE-N electrode has better ability to withstand large current operation. This can be attributed to the multi-dimensional structure of the all-biomass carbon-based electrode, which provides additional active sites to accelerate the electrochemical activity of the electrode and reduce the voltage drop on the electrode surface.

[0068] Example 11

[0069] The 80-mesh sieve screened bamboo powder and sodium carboxymethyl cellulose were weighed according to a mass ratio of 8:1, 1 g of the bamboo powder and 0.125 g of the sodium carboxymethyl cellulose were taken, 32 mL of deionized water was added, and the mixture was fully stirred to obtain a uniform slurry, which was then poured into a mold, tapped appropriately, and left to stand for 10 min to remove bubbles, and then the mixture was rapidly frozen in liquid nitrogen and placed in a freeze dryer for 48 h, thereby obtaining a bamboo-based precursor. Finally, the bamboo-based precursor was placed in a high-temperature tube furnace, carbonized at 1100 DEG C under a N2 atmosphere, and held for 2 h, thereby obtaining a full-biomass carbon-based electrode material.

[0070] The electrode material prepared in this example was used as a working electrode, a platinum electrode was used as a counter electrode, and a Hg / HgSO4 electrode was used as a reference electrode to construct a three-electrode unit system of a vanadium redox flow battery. The electrolyte was composed of 0.1 mol / L VOSO4 and 2.0 mol / L H2SO4. The three-electrode system was subjected to cyclic voltammetry testing, and the scan rate was set to 10 mV / s. The cyclic voltammogram is shown in FIG. 6. Figure 4

[0071] Example 12

[0072] The 80-mesh sieve screened bamboo powder and sodium carboxymethyl cellulose were weighed according to a mass ratio of 2:1, 1 g of the bamboo powder and 0.5 g of the sodium carboxymethyl cellulose were taken, 32 mL of deionized water was added, and the mixture was fully stirred to obtain a uniform slurry, which was then poured into a mold, tapped appropriately, and left to stand for 10 min to remove bubbles, and then the mixture was rapidly frozen in liquid nitrogen and placed in a freeze dryer for 48 h, thereby obtaining a bamboo-based precursor. Finally, the bamboo-based precursor was placed in a high-temperature tube furnace, carbonized at 1100 DEG C under a N2 atmosphere, and held for 2 h, thereby obtaining a full-biomass carbon-based electrode material.

[0073] The electrode material prepared in this example was used as a working electrode, a platinum electrode was used as a counter electrode, and a Hg / HgSO4 electrode was used as a reference electrode to construct a three-electrode unit system of a vanadium redox flow battery. The electrolyte was composed of 0.1 mol / L VOSO4 and 2.0 mol / L H2SO4. The three-electrode system was subjected to cyclic voltammetry testing, and the scan rate was set to 10 mV / s. The cyclic voltammogram is shown in FIG. 6. Figure 4

[0074] Figure 4 The cyclic voltammograms of the electrode materials obtained in Examples 10, 11, and 12 show that the full-biomass carbon-based electrode obtained by carbonizing the bamboo-based precursor mixed with sodium carboxymethyl cellulose at a mass ratio of 4:1 has the largest oxidation peak current (129.3 mA) and a smaller peak potential difference (0.50 V), indicating that it has the best electrochemical performance. This indicates that the optimal mixing ratio of bamboo powder and sodium carboxymethyl cellulose is 4:1.

[0075] ​​Finally, it should be noted that the above examples are merely intended to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A method for preparing a full-biomass carbon-based electrode for a full vanadium redox flow battery, characterized in that, The method comprises the following steps: (S1) cutting the biomass raw material into small pieces, washing with deionized water and anhydrous ethanol, and then naturally drying and placing in an oven for drying; (S2) placing the dry and clean biomass raw material into a crusher to break into powder, and sieving; (S3) taking biomass powder and sodium carboxymethyl cellulose according to a mass ratio, adding a proper amount of deionized water, and fully stirring to obtain a uniform slurry; (S4) pouring the slurry into a mold for shaping, thereby obtaining a biomass-based precursor; (S5) placing the biomass-based precursor in a high-temperature tube furnace and heating under N2 atmosphere to obtain a full-biomass carbon-based electrode material; In step (S1), the biomass raw material comprises bamboo and wood. In step (S3), the mass ratio of the biomass powder to sodium carboxymethyl cellulose is 2:1-8:

1. In step (S5), the heating temperature is 600-1200 ℃, and the heating time is 1-3 h.

2. The process for the preparation of an all-biomass carbon-based vanadium flow battery electrode according to claim 1, characterized in that, In step (S1), the drying temperature is 60-80 ℃.

3. The process for the preparation of an all-biomass carbon-based vanadium flow battery electrode according to claim 1, characterized in that, In step (S2), the sieving screen specification is 40-200 mesh.

4. The process for the preparation of an all-biomass carbon-based vanadium flow battery electrode according to claim 1, characterized in that, In step (S4), the slurry shaping method comprises drying and freeze-drying.

5. The process for the preparation of an all-biomass carbon-based vanadium redox flow battery electrode according to claim 4, characterized in that, The drying conditions are: drying at 60-80 ℃ for 24-36 h; the freeze-drying conditions are: drying at -60--20 ℃ for 36-72 h.

6. The process for the preparation of an all-biomass carbon-based vanadium redox flow battery electrode according to claim 1, characterized in that, In step (S5), the heating temperature is 1100 ℃, and the heating time is 2 h.

7. A full-biomass carbon-based all-vanadium redox flow battery electrode prepared by the preparation method according to any one of claims 1-6.

8. Use of a full biomass carbon-based all-vanadium redox flow battery electrode according to claim 7, characterized in that, An all-vanadium redox flow battery electrode is used as a working electrode, a platinum electrode is used as a counter electrode, and a Hg / Hg2SO4 electrode is used as a reference electrode to construct a three-electrode unit system of the all-vanadium redox flow battery for electrochemical performance testing.

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