Preparation of Co9S8 / Ni7S6 heterostructure electrode, and preparation and application of paper-based coplanar miniature supercapacitor

Abstract

The invention discloses preparation of a Co9S8 / Ni7S6 heterostructure electrode and preparation and application of a paper-based coplanar miniature supercapacitor, a nickel source, a cobalt source and sodium thiosulfate are uniformly mixed to obtain an electrolyte for deposition, a patterned nickel metal electrode is immersed in the electrolyte for deposition, electro-deposition is performed on one side of the patterned nickel metal electrode by adopting a three-electrode system, and the paper-based coplanar miniature supercapacitor is obtained. And the Co9S8 / Ni7S6 heterostructure positive electrode is obtained. According to the invention, the cobalt-nickel sulfide Co9S8 / Ni7S6 is directly deposited on the current collector through a one-step electrodeposition method, so that the influence of an organic adhesive on an electrode is eliminated, and the binding power is stronger. The paper-based coplanar miniature supercapacitor prepared by using the electrode shows excellent cycling stability and energy density. Even under the folding condition, the capacity of the coplanar miniature supercapacitor is almost kept unchanged, and the coplanar miniature supercapacitor has excellent mechanical stability and practicability.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrode materials, and in particular relates to the preparation of Co9S8 / Ni7S6 heterostructure electrodes, and the preparation and application of paper-based coplanar micro supercapacitors. Background Art

[0002] With the rapid development of new portable devices and wearable electronic products, miniaturized and flexible power supply systems are in urgent need of research and development. Among the various available power supply devices, micro-supercapacitors have become the most popular and promising research targets due to their excellent power density and excellent cycle stability. Among them, coplanar micro-supercapacitors (CMSCs) have attracted a lot of attention due to their unique structural configuration and simple integration method. However, considering the inherent characteristics of supercapacitors and the limited load capacity of microscale electrode materials, their energy density still cannot meet the needs of large-scale practical applications. The solution to this problem in existing technologies is usually to develop electrode materials with higher capacitance, such as metal sulfides, selenides, oxides and hydroxides.

[0003] As a star material in the field of supercapacitors, transition metal sulfides (TMS) have significant cost advantages, excellent conductivity and a large number of redox sites. Specifically, binary metal sulfides have multiple oxidation states and synergistic effects, which can provide higher capacitance and better cycling stability than single metal sulfides. One of the typical materials is cobalt nickel sulfide, which forms a large number of heterogeneous interfaces during the nucleation process and has a larger theoretical capacity and morphological adjustability. However, the use of TMS in CMSCs still faces many challenges: traditional low-crystalline transition metal cobalt nickel sulfide has poor mechanical strength; the synthesis method is relatively harsh, and the bonding between the electrode material and the substrate is weak. Summary of the Invention

[0004] In order to overcome the problems in the prior art, the present invention provides a preparation of a Co9S8 / Ni7S6 heterostructure electrode, the preparation and application of a paper-based coplanar micro supercapacitor. A Co9S8 / Ni7S6 heterostructure with a high crystalline structure is obtained by a one-step electrodeposition method. The synthesis method is simple and can be directly deposited on a nickel metal current collector on a flexible paper base. The prepared coplanar micro supercapacitor exhibits excellent cycle stability and high energy density.

[0005] In order to solve the above technical problems, the technical solutions proposed by the present invention are as follows: The present invention provides a preparation method of a Co9S8 / Ni7S6 heterostructure electrode, comprising the following steps: uniformly mixing a nickel source, a cobalt source and sodium thiosulfate to obtain a deposition electrolyte, immersing a patterned nickel metal electrode in the deposition electrolyte, and performing electrodeposition on one side of the patterned nickel metal electrode using a three-electrode system to obtain a Co9S8 / Ni7S6 heterostructure positive electrode.

[0006] In the present invention, a nickel source, a cobalt source and sodium thiosulfate are evenly mixed to obtain a deposition electrolyte, and Co9S8 / Ni7S6 with a high crystal structure and a heterostructure is prepared by a one-step electrochemical deposition method. In addition, the Co9S8 / Ni7S6 heterostructure can be directly deposited onto a nickel metal electrode on a flexible paper base during the deposition process.

[0007] As an optional embodiment, in the method provided by the present invention, the content of sodium thiosulfate in the deposition electrolyte is 0.25-0.75 mmol. The morphology of the heterojunction can be further controlled by controlling the sulfur content.

[0008] As an optional embodiment, in the method provided by the present invention, the molar ratio of nickel to cobalt in the nickel source and the cobalt source in the deposition electrolyte is 5:2-2:5.

[0009] In the present invention, the molar ratio of nickel to cobalt is controlled within the range of 5:2-2:5 to prepare a Co9S8 / Ni7S6 heterostructure with certain properties.

[0010] As an optional embodiment, in the method provided by the present invention, nickel, platinum wire and saturated calomel electrode are used as the working electrode, counter electrode and reference electrode respectively in the three-electrode system.

[0011] As an optional embodiment, in the method provided by the present invention, the cyclic voltammetry of the electrodeposition technique is performed at a scan rate of 2-50 mV s -1 , the voltage range is -1.2-0.2 V, and the number of cycles is 2-10.

[0012] In the present invention, controlling the electrodeposition technical parameters within the above range is conducive to the realization of deposition. The slower the scanning speed, the better the nucleation.

[0013] Based on the same technical concept, the present invention also provides a method for preparing a paper-based coplanar micro supercapacitor, comprising the following steps: S1. Screen-print the catalytic ink onto filter paper and prepare a patterned nickel metal electrode by electroless deposition.

[0014] S2. Evenly mix the nickel source, cobalt source and sodium thiosulfate to obtain a deposition electrolyte, immerse the patterned nickel metal electrode prepared in step S1 in the deposition electrolyte, and use a three-electrode system to perform electrodeposition on one side of the patterned nickel metal electrode to obtain a Co9S8 / Ni7S6 heterostructure material as the positive electrode of the coplanar micro supercapacitor.

[0015] S3. Apply activated carbon ink as the negative electrode material on the other side of the nickel metal electrode, and after drying, obtain a patterned electrode loaded with positive and negative electrode materials.

[0016] S4. Potassium hydroxide gel electrolyte is applied to the intersection area of ​​the patterned electrodes, and then the entire device is sealed to obtain a paper-based coplanar micro supercapacitor.

[0017] The Co9S8 / Ni7S6 heterostructure prepared by the present invention can be applied to coplanar micro supercapacitors, and the prepared coplanar micro supercapacitors exhibit excellent cycle stability and high energy density.

[0018] As an optional embodiment, in the method provided by the present invention, in step S1, the catalytic ink consists of an aqueous solution of (NH4)2PdCl4 and polyethylene glycol.

[0019] As an optional embodiment, in the method provided by the present invention, in step S1, the bath used for electroless deposition contains NiSO4, sodium citrate, lactic acid, dimethylamine borane and NH3·H2O.

[0020] As an optional embodiment, in the method provided by the present invention, in step S1, during the deposition process, when the resistance of the nickel metal electrode drops to 5Ω or less, the filter paper is removed from the electroless deposition bath. To ensure the conductivity of the current collector, the metal electrode is removed when its resistance drops to 5Ω or less.

[0021] As an optional embodiment, in the method provided by the present invention, in step S3, the activated carbon ink is prepared by mixing activated carbon, polyvinylidene fluoride and Super P in a ratio of 8:1:1 and adding N-methylpyrrolidone (NMP).

[0022] As an optional embodiment, in the method provided by the present invention, in step S4, the potassium hydroxide gel electrolyte is obtained by dissolving polyvinyl alcohol in water, then slowly adding potassium hydroxide (KOH) solution to the transparent solution obtained in the previous step, stirring and cooling.

[0023] Based on the same technical concept, the present invention also provides the application of the Co9S8 / Ni7S6 heterostructure electrode prepared by the above-mentioned preparation method of the Co9S8 / Ni7S6 heterostructure electrode in a paper-based coplanar micro-supercapacitor. The application method is as follows: immersing the nickel metal electrode in a deposition electrolyte obtained by mixing a nickel source, a cobalt source and sodium thiosulfate, and using a three-electrode system to directly electrodeposit the above-mentioned raw materials onto one side of the patterned nickel metal electrode to obtain a Co9S8 / Ni7S6 heterostructure electrode on the nickel metal electrode.

[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) In the present invention, the Co9S8 / Ni7S6 heterostructure synthesized from a nickel source, a cobalt source and sodium thiosulfate is directly deposited on a nickel metal current collector on a flexible paper substrate by a one-step electrodeposition method, thereby avoiding the complex methods of using step-by-step deposition or tubular furnace heat treatment in the prior art, and the synthesis method is simple.

[0025] (2) In the present invention, the cobalt nickel sulfide Co9S8 / Ni7S6 is deposited directly on the current collector, which not only avoids the problem of some active materials not participating in the electrochemical reaction, but also eliminates the influence of organic binders on the electrode. Compared with the technology of using binders to bond powder materials to the current collector, the method of direct growth on the current collector by electrodeposition has stronger bonding force.

[0026] (3) The paper-based coplanar micro supercapacitor prepared using cobalt nickel sulfide Co9S8 / Ni7S6 in the present invention exhibits excellent cycle stability (capacity retention rate reaches 93.4% after 8000 cycles) and achieves 0.03145 mWh cm -2 Even when the CMSC is folded, the capacity of the coplanar micro-supercapacitor remains almost unchanged, showing excellent mechanical stability and practicality.

[0027] (4) Metal sulfides exhibit more significant electrochemical activity due to their larger lattice size and more complex valence state. Compared with other electrode materials, the cobalt nickel sulfide Co9S8 / Ni7S6 prepared in the present invention has higher mechanical stability and thermal stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1Scanning electron microscope (SEM) images of CNS-0.5, CNS-0.25, CNS-0.75, and CNS-0 prepared in Examples and Comparative Examples, wherein Figure (a) is CNS-0, Figure (b) is CNS-0.25, Figure (c) is CNS-0.5, and Figure (d) is CNS-0.75; Figure 2 : This is a transmission electron microscope (TEM) image of CNS-0.5 prepared in the example; Figure 3 High-resolution transmission electron microscopy (HR-TEM) images of CNS-0.5 prepared in the examples, with fast Fourier transform (FFT) patterns of the designated areas; Figure 4 Energy dispersive X-ray (EDX) mapping and cobalt (Co), nickel (Ni) and sulfur (S) elemental spectra of CNS-0.5 prepared in the examples; Figure 5 is the X-ray diffraction pattern of CNS-0.5 prepared in the examples; Figure 6 The crystal optimization model, density state distribution model, and charge density difference model of the heterojunction of Co9S8, Ni7S6, and Co9S8 / Ni7S6 were simulated using ASP software. Figure (a) shows Co9S8, Figure (b) shows Ni7S6, and Figure (c) shows Co9S8 / Ni7S6. Figure (d) shows the density state distribution of Co9S8, Ni7S6, and Co9S8 / Ni7S6 heterojunctions. Figure (e) shows the charge density difference at the interface of the Co9S8 / Ni7S6 heterojunction. Figure 7 For coplanar micro-supercapacitors in the range of 5-100 mV s -1 Cyclic voltammetry curves below; Figure 8 For coplanar micro-supercapacitors at 1.5-4 mA cm -2 In situ electrochemical depolarization curve under ; Figure 9 For coplanar micro-supercapacitors at 1.5-4 mA cm -2 Rate performance results under ; Figure 10 is the Ragone curve of the coplanar micro-supercapacitor; Figure 11 For coplanar micro-supercapacitors at 4 mA cm -2 Cyclic performance results under Figure 12 Digital photos of coplanar micro-supercapacitors in four different bending states; Figure 13Cyclic voltammetry (CV) curves and constant current charge-discharge (GCD) curves of coplanar micro supercapacitors at different bending angles, where (a) is the CV curve and (b) is the GCD curve. DETAILED DESCRIPTION

[0030] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0031] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0032] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0033] Example 1 Preparation of Co9S8 / Ni7S6 heterostructure: After cleaning nickel foam with acetone, water and ethanol, it was immersed in the electrolyte for electrodeposition as the growth substrate of Co9S8 / Ni7S6. The electrolyte contained 1.5 mmol Ni(NO3)2·6H2O, 0.75 mmol Co(NO3)2·6H2O, 0.5 mmol Na2S2O3 and 50 mL water. The electrodeposition used a three-electrode system: NF (nickel foam), platinum (Pt) wire and saturated calomel electrode (SCE) as working electrode, counter electrode and reference electrode, respectively. Among them, the effective area of ​​NF immersed in the electrodeposition solution was 1×1 cm². The specific parameters of cyclic voltammetry used as the electrodeposition technique were fixed at a scan rate of 5 mV s -1 , with a voltage range of -1.2 to 0.2 V for two cycles. After completing the above steps, the Co9S8 / Ni7S6-loaded NF was repeatedly washed with ethanol and water and then dried in vacuum at 60°C overnight. A Co9S8 / Ni7S6 heterojunction was obtained through this method and labeled as CNS-0.5.

[0034] Example 2 The difference from Example 1 is that the amount of Na2S2O3 is 0.25 mmol, and the other conditions are the same as those in Example 1, and a Co9S8 / Ni7S6 heterojunction is obtained, which is marked as CNS-0.25.

[0035] Example 3 The difference from Example 1 is that the amount of Na2S2O3 is 0.75 mmol, and the other conditions are the same as those in Example 1, and a Co9S8 / Ni7S6 heterojunction is obtained, which is marked as CNS-0.75.

[0036] Comparative Example 1 The difference from Example 1 is that the amount of Na2S2O3 is 0 mmol, and the other conditions are the same as in Example 1. The obtained product is marked as CNS-0.

[0037] Performance testing The CNS-0.5, CNS-0.25, CNS-0.75 and CNS-0 prepared in Examples 1-3 and Comparative Example 1 were examined by scanning electron microscopy (SEM). The results were as follows: Figure 1 The results show the successful growth of CNS-0.5, CNS-0.25, CNS-0.75, and CNS-0 on the NF surface. The microstructure of CNS-0 prepared in Comparative Example 1 consists of irregular nanosheets arranged in a honeycomb array, as shown in Figure (a). With the introduction of sulfur, the sample's morphology undergoes a transition from planar to three-dimensional. When the Na2S2O3 content is 0.25 mmol, as shown in Figure (b), CNS-0.25 lacks a distinct regular shape. With increasing Na2S2O3 addition, CNS-0.5 forms a nanoflower shape, as shown in Figure (c). Finally, when the Na2S2O3 addition reaches 0.75 mmol, the morphology of CNS-0.75 reveals three-dimensional stacked nanospheres, as shown in Figure (d). Because the nanoflower structure is most conducive to electrolyte transport and active site exposure, it is inferred that the prepared CNS-0.5 exhibits the best performance for coplanar micro-supercapacitors.

[0038] The CNS-0.5 prepared in Example 1 was examined by transmission electron microscopy (TEM), and the results were as follows: Figure 2 As shown, the results indicate that the nanoflower-like CNS-0.5 is composed of interlaced and interconnected nanosheets.

[0039] The CNS-0.5 prepared in Example 1 was examined by high-resolution transmission electron microscopy (HR-TEM), and the fast Fourier transform (FFT) pattern of the designated area was attached. The results are as follows: Figure 3 As shown in the figure, the high-resolution TEM image obtained by further magnification shows a clear heterogeneous interface. The lattice spacing on both sides of the interface is 0.247 nm and 0.285 nm, respectively, which is very consistent with the subsequent XRD results and corresponds to the (400) crystal plane of Co9S8 and the (121) crystal plane of Ni7S6.

[0040] The CNS-0.5 prepared in Example 1 was subjected to energy dispersive X-ray spectroscopy (EXD) mapping and the corresponding element spectrum. The results are as follows: Figure 4As shown, the EDX mapping image shows that the elements (Ni, Co, S) are densely present on CNS-0.5.

[0041] The X-ray diffraction analysis of CNS-0.5 prepared in Example 1 showed that Figure 5 As shown, XRD clearly shows the crystal structure of CNS-0.5. Although the peaks of NF (JCPDS 04-0850) used as the substrate may interfere with the diffraction signals of CNS-0.5 due to their high intensity, it can still be seen that the characteristic peaks at 15.5°, 29.9°, 36.1°, 47.4°, 73.3° and 76.7° correspond to the Co9S8 (111), (311), (400), (511), (731) and (800) crystal planes provided by the JCPDS 19-0364 standard card. The peaks at angles of 15.6°, 27.3°, 31.2°, 38.6°, 50.5° and 55.4° can be attributed to the Ni7S6 phase (JCPDS 14-0364). This shows that a Co9S8 / Ni7S6 heterostructure was prepared.

[0042] Figure 6 Figure 2 shows crystal optimization models of (a) Co9S8, (b) Ni7S6, and (c) Co9S8 / Ni7S6 heterojunctions simulated using ASP software. Figure (d) shows the density of states distribution for Co9S8, Ni7S6, and Co9S8 / Ni7S6 heterojunctions; Figure (e) shows the charge density difference at the Co9S8 / Ni7S6 heterojunction interface. Figures (a)-(e) demonstrate the rapid electron transfer in the Co9S8 / Ni7S6 heterostructure, exceeding that of the single components Co9S8 and Ni7S6.

[0043] The preparation embodiment of the paper-based coplanar micro supercapacitor comprises the following steps: (1) Preparation of negative electrode ink Activated carbon (AC) ink is prepared by mixing acidified commercial activated carbon with polyvinylidene fluoride (PVDF) and Super P in a ratio of 8:1:1, and then adding an appropriate amount of N-methylpyrrolidone (NMP). In particular, the amount of NMP can be adjusted to make the viscosity of the AC ink suitable for screen printing.

[0044] (2) Synthesis of KOH gel electrolyte A typical synthesis procedure involves dissolving 3 grams of polyvinyl alcohol (PVA) in 10 milliliters of water under heating and vigorous stirring. Subsequently, 10 milliliters of a 5.3 mol / L potassium hydroxide (KOH) solution is slowly added dropwise to the clear solution obtained in the previous step. During stirring and cooling, the mixed solution forms a uniform potassium hydroxide gel.

[0045] (3) Preparation of catalytic ink The catalytic ink consisted of (NH4)2PdCl4 (46 mg), polyethylene glycol (PEG, 2 g), and water (4.6 mL).

[0046] (4) Preparation of coplanar micro-supercapacitors First, the catalytic ink was printed onto untreated filter paper by screen printing. After standing for five minutes, the patterned printed filter paper was immersed in 50 mL of electroless deposition (ELD) solution containing 0.6 M NiSO4·6H2O, 0.3 M sodium citrate, 0.4 M lactic acid, 0.01 M DMAB and a small amount of NH3·H2O to complete the nickel metal deposition. When the resistance of the patterned nickel metal electrode dropped to 5 Ω or below, the filter paper was removed from the solution. The substrate was rinsed with clean water several times and then dried. The filter paper was then immersed in the electrolyte for electrodeposition to electrodeposit CNS on one side of the electrode. 0.5 The positive electrode of the coplanar micro-supercapacitor was prepared using an electrolyte containing 1.5 mmol of Ni(NO₃)₂·6H₂O, 0.75 mmol of Co(NO₃)₂·6H₂O, 0.5 mmol of Na₂S₂O₃, and 50 mL of water. Electrodeposition was performed using a three-electrode system: a platinum (Pt) wire and a saturated calomel electrode (SCE) as the counter and reference electrodes, respectively. Cyclic voltammetry parameters for the electrodeposition technique were fixed at a scan rate of 5 mV s⁻¹. -1 Two cycles were performed over a voltage range of -1.2 to 0.2 V. Activated carbon (AC) ink, serving as the negative electrode material, was screen-printed onto the other side of the nickel metal electrode. After drying, the patterned electrodes loaded with positive and negative electrode materials were coated with a KOH gel electrolyte at the intersection of the interdigitated electrodes. Finally, the entire device was sealed with 3M tape to prevent evaporation of water from the electrolyte.

[0047] The performance of the prepared coplanar micro supercapacitor (CMSC) was tested. CMSC has a capacitance of 5-100 mV s -1 The cyclic voltammetry curve is as follows Figure 7 As shown, the coplanar micro-supercapacitors can operate at 1.5-4 mA cm -2 The in situ electrochemical depolarization curve under Figure 8 As shown by Figure 7 and Figure 8 It can be seen that the chopper-shaped CV curves at different scan rates and the pseudo-isosceles triangle GCD curves at different current densities once again confirm that IPMSC is a hybrid supercapacitor with well-matched positive and negative electrodes.

[0048] Coplanar micro-supercapacitors at 1.5-4 mA cm -2 The rate performance curve is as follows: Figure 9 As shown by Figure 9It can be seen that IPMSC is in the range of 1.5-4 mA cm -2 The capacity retention rate is higher.

[0049] The Ragone curve of the coplanar micro supercapacitor is as follows: Figure 10 As shown in Table 1, the composition of other devices is shown in Table 1. Figure 10 The Ragone plot and Table 1 show that the energy density of IPMSC is much higher than that of other devices. -2 The energy density is as high as 0.03145 mWh cm -2 , and at a power density of 2.98 mW cm -2 When the energy density is still maintained at 0.01298 mWh cm -2 .

[0050] Table 1: Performance comparison of IPMSC prepared by the present invention and other devices

[0051] Coplanar micro-supercapacitors at 4 mA cm -2 The cycle performance under Figure 11 As shown by Figure 11 It can be seen that after 8,000 charge and discharge cycles, the capacitance retention rate reached 93.4%, proving that it has excellent cycle performance.

[0052] The prepared coplanar micro-supercapacitor was bent, and digital photos of four different bending states are shown as follows. Figure 12 As shown in Figure 2, the four bending states represent the deformations that may occur in IPMSCs in practical applications. The cyclic voltammetry (CV) curves (a) and constant current charge-discharge (GCD) curves (b) under different bending states are shown in Figure 2. Figure 13 As shown in , the two representative features, the shape of the curve and the area of ​​the enclosed region, have not changed significantly. Figure 13 It can be seen that IPMSC is flexible enough to adapt to any extreme deformation, even when applied in a folded manner.

[0053] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for preparing a Co9S8 / Ni7S6 heterostructure electrode, characterized in that: The following steps are involved: The nickel source, cobalt source and sodium thiosulfate are evenly mixed to obtain a deposition electrolyte, the patterned nickel metal electrode is immersed in the deposition electrolyte, and a three-electrode system is used to perform electrodeposition on one side of the patterned nickel metal electrode to obtain a Co9S8 / Ni7S6 heterostructure positive electrode.

2. The preparation of the Co9S8 / Ni7S6 heterostructure electrode according to claim 1, characterized in that: The content of sodium thiosulfate in the deposition electrolyte is 0.25-0.75 mmol.

3. The method for preparing the Co9S8 / Ni7S6 heterostructure electrode according to claim 1, characterized in that: The molar ratio of nickel to cobalt in the nickel source and the cobalt source in the deposition electrolyte is 5:2-2:

5.

4. The method for preparing the Co9S8 / Ni7S6 heterostructure electrode according to claim 1, characterized in that: In the three-electrode system, nickel, platinum wire and saturated calomel electrode were used as working electrode, counter electrode and reference electrode, respectively.

5. The method for preparing the Co9S8 / Ni7S6 heterostructure electrode according to claim 1, wherein: The cyclic voltammetry of the electrodeposition technique was performed at a scan rate of 2-50 mV s- 1 , the voltage range is -1.2-0.2 V, and the number of cycles is 2-10.

6. A method for preparing a paper-based coplanar micro supercapacitor, characterized in that: The following steps are involved: S1. Screen printing the catalytic ink onto filter paper and preparing a patterned nickel metal electrode by electroless deposition; S2. Evenly mixing a nickel source, a cobalt source, and sodium thiosulfate to obtain a deposition electrolyte, immersing the patterned nickel metal electrode prepared in step S1 in the deposition electrolyte, and performing electrodeposition on one side of the patterned nickel metal electrode using a three-electrode system to obtain a Co9S8 / Ni7S6 heterostructure material as the positive electrode of a coplanar micro supercapacitor; S3, coating the activated carbon ink as the negative electrode material on the other side of the nickel metal electrode, and drying to obtain a patterned electrode loaded with positive and negative electrode materials; S4. Potassium hydroxide gel electrolyte is applied to the intersection area of ​​the patterned electrodes, and then the entire device is sealed to obtain a paper-based coplanar micro supercapacitor.

7. The method for preparing a paper-based coplanar micro supercapacitor according to claim 6, characterized in that: In step S1, the catalytic ink is composed of an aqueous solution of (NH4)2PdCl4 and polyethylene glycol.

8. The method for preparing a paper-based coplanar micro supercapacitor according to claim 1, characterized in that: In step S1, the bath solution used for electroless deposition contains NiSO4, sodium citrate, lactic acid, dimethylamine borane and NH3·H2O.

9. The method for preparing a paper-based coplanar micro supercapacitor according to claim 1, characterized in that: In step S1, during the deposition process, when the resistance of the nickel metal electrode drops to 5Ω or below, the filter paper is removed from the electroless deposition bath.

10. Use of the Co9S8 / Ni7S6 heterostructure electrode prepared by the method for preparing the Co9S8 / Ni7S6 heterostructure electrode according to any one of claims 1 to 5 in a paper-based coplanar micro-supercapacitor.

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