Super capacitor and lithium battery-super capacitor hybrid energy storage device

Abstract

The invention provides a super capacitor and a lithium battery-super capacitor hybrid energy storage device. The high-energy-density super capacitor comprises a dielectric layer, and the dielectric layer comprises a conductive substrate, an active material layer and an insulating layer which are arranged in sequence. Wherein the active substance layer comprises nitrogen and sulfur functionalized carbon foam magnetic microspheres as active substances. The lithium battery-super capacitor hybrid energy storage device comprises a lithium battery, an inductance coil, the super capacitor, a control circuit and load electric equipment. According to the supercapacitor, the nitrogen and sulfur functionalized carbon foam magnetic microspheres are innovatively adopted as conductive active substances, the energy density is high, and the charging speed is high. In the lithium battery-super capacitor hybrid energy storage device, the lithium battery and the super capacitor can be mutually charged, the current is more stable and safer, and the charging and discharging efficiency is high.

Description

Technical Field

[0001] The present invention relates to the field of mechanical technology, in particular to the field of battery technology. Background Art

[0002] Forklifts are industrial handling vehicles, which refer to various wheeled handling vehicles for loading and unloading, stacking and short-distance transportation of palletized goods. The International Organization for Standardization ISO / TC110 calls them industrial vehicles. They are often used for the transportation of large objects in storage, usually powered by fuel engines or batteries. Electric forklifts are forklifts driven by electrical energy, and currently mainly use lithium batteries and lead-acid batteries for chemical energy storage. Compared with general electric vehicles, electric forklifts have higher requirements for power output and current output stability when lifting goods.

[0003] However, when chemical batteries such as lithium batteries convert chemical energy into electrical energy (during battery charging and discharging), ions tend to flow back and forth between the cathode and the anode. Chemical batteries generally include a positive electrode and a negative electrode, which are immersed in a liquid electrolyte and separated by a microporous ion exchange membrane that only allows ions to pass through. During the charge and discharge of chemical batteries, ions tend to flow back and forth between the anode and the cathode. When these ions are transferred, it causes the battery to heat up, expand, and then shrink. These reactions gradually degrade the battery, resulting in a shortened battery life. There are also safety issues such as long charging time, high price, overcharging causing heating and combustion, and regular charging and maintenance are required, which is inconvenient to use. Summary of the invention

[0004] In view of the above problems, the present invention provides a high energy density supercapacitor, which innovatively uses nitrogen and sulfur functionalized carbon foam magnetic microspheres as conductive active materials, has high energy density and fast charging speed.

[0005] The present invention also provides a lithium battery-supercapacitor hybrid energy storage device, in which the lithium battery and the supercapacitor can charge each other, and the current is more stable, improving safety performance. At the same time, the above-mentioned high-energy density supercapacitor is used to further improve the charging and discharging efficiency of the device.

[0006] In order to achieve the above-mentioned object, the first aspect of the present invention provides a high energy density supercapacitor, the supercapacitor includes a dielectric layer, the dielectric layer includes a conductive substrate, an active material layer and an insulating layer arranged in sequence; wherein the active material layer includes nitrogen and sulfur functionalized carbon foam magnetic microspheres as active materials.

[0007] Preferably, the conductive substrate is selected from corroded aluminum foil and / or polyvinylidene fluoride; the active material layer is composed of nitrogen and sulfur functionalized carbon foam magnetic microspheres and adhesive in a mass percentage of 90-95%:5-10%; the insulating layer includes graphite, polyimide glue and adhesive in a mass percentage of 75-80%:4-10%:5-10%.

[0008] Preferably, the adhesive is selected from a mixed water-soluble adhesive comprising styrene-butadiene rubber and sodium carboxymethyl cellulose.

[0009] Preferably, the active material layer includes nitrogen and sulfur functionalized carbon foam magnetic microspheres as active materials in an amount of not less than 90% by mass.

[0010] Preferably, the conductive substrate includes a positive conductive substrate and a negative conductive substrate, and the active material layer includes a positive active material layer and a negative active material layer; in the dielectric layer, the positive conductive substrate, the positive active material layer, the insulating layer, the negative active material layer and the negative conductive substrate are arranged in sequence.

[0011] Preferably, the method for preparing the dielectric layer of the supercapacitor comprises the following steps:

[0012] (1) mixing nitrogen and sulfur functionalized carbon foam magnetic microspheres and a binder with water and stirring to obtain a first mixture;

[0013] The binder is mixed with water to form a slurry, and the insulating material is gradually added to the slurry to obtain a second mixture;

[0014] (2) coating the first mixture on the surface of the positive electrode conductive substrate and the negative electrode conductive substrate, respectively, and drying to obtain a positive electrode conductive substrate-active material layer and a negative electrode conductive substrate-active material layer;

[0015] (3) The second mixture is coated between the positive electrode conductive substrate-active material layer and the negative electrode conductive substrate-active material layer, and dried to form a dielectric layer in which the positive electrode conductive substrate, the positive electrode active material layer, the insulating layer, the negative electrode active material layer and the negative electrode conductive substrate are arranged in sequence.

[0016] Preferably, in step (2), the coating thickness of the first mixture is 0.2 to 0.25 mm, the drying temperature is 80 to 90° C., and the drying time is more than 5 hours;

[0017] In step (3), the coating thickness of the second mixture is 0.02-0.03 μm, the drying temperature is 80-90° C., and the drying time is more than 5 hours.

[0018] Preferably, the supercapacitor also includes a magnetic fixing structure, which includes a negative pole internal magnetic field structure and a positive pole external magnetic field structure. The dielectric layer is arranged between the negative pole internal magnetic field structure and the positive pole external magnetic field structure. The magnetic field formed by the negative pole internal magnetic field structure and the positive pole external magnetic field structure can cause the nitrogen and sulfur functionalized carbon foam magnetic microspheres in the positive pole active material layer and the negative pole active material layer to adsorb and compact each other.

[0019] Preferably, the magnetic fixed structure is cylindrical, including a cylindrical negative pole inner magnetic field structure and an annular positive pole outer magnetic field structure; the dielectric layer is a circular ring; the cylindrical negative pole inner magnetic field structure, the annular positive pole outer magnetic field structure and the dielectric layer are concentric; the bottoms of the cylindrical negative pole inner magnetic field structure and the annular positive pole outer magnetic field structure are connected.

[0020] Preferably, the energy density of the supercapacitor is at least 4.5 kWh / kg and the charging efficiency is not less than 91%.

[0021] The second aspect of the present invention provides a lithium battery-supercapacitor hybrid energy storage device, including a lithium battery, an inductor, a supercapacitor, a control circuit and a load electrical device; the lithium battery, the inductor and the supercapacitor are connected in series to form a first circuit, and the inductor is used to delay the current change of the lithium battery; the first circuit is connected in parallel with the supercapacitor to form a second circuit; the supercapacitor and the control circuit are connected in series to form a third circuit, and the control circuit is connected to the load electrical device and can control the load electrical device to be connected or disconnected.

[0022] Preferably, the lithium battery is a lithium iron phosphate battery.

[0023] Preferably, the first circuit further comprises a power detection device connected in parallel with the lithium battery, for detecting the power of the lithium battery.

[0024] Preferably, the inductor coil has at least 20 turns.

[0025] Preferably, the supercapacitor is the supercapacitor according to any one of claims 1-10.

[0026] A third aspect of the present invention provides an electric forklift, comprising the lithium battery-supercapacitor hybrid energy storage device described in the above technical solution.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention uses a high energy density supercapacitor that can hold more electricity as a reserve, with a charging efficiency of 91%, which can meet the needs of forklifts and other equipment that require a large amount of electricity supply.

[0029] The supercapacitor described in the present invention creatively uses a "nitrogen and sulfur functionalized carbon foam magnetic microsphere" material used for environmental governance as an electrode. For detailed information on the material, please refer to the Chinese patent "ZL201510359764.4, a method for preparing nitrogen and sulfur functionalized carbon foam magnetic microspheres". The material is a new type of carbon material composed of carbon atoms with a honeycomb porous network skeleton structure, with low density, large specific surface area, and good conductivity. Compared with ordinary carbon powder, it has a regular shape and is easier to disperse during use. The inventor unexpectedly discovered that the magnetic microsphere has excellent energy storage properties and charge and discharge efficiency when used as an active material for supercapacitors.

[0030] 2. In some preferred embodiments of the present invention, in order to further increase the number of charge and discharge times of the supercapacitor and extend the service life of the supercapacitor, the supercapacitor also includes a magnetic fixing structure, the magnetic fixing structure includes a negative pole internal magnetic field structure (S pole) and a positive pole external magnetic field structure (N pole), and the dielectric layer is arranged between the negative pole internal magnetic field structure and the positive pole external magnetic field structure. The magnetic field formed by the negative pole internal magnetic field structure and the positive pole external magnetic field structure can cause the nitrogen and sulfur functionalized carbon foam magnetic microspheres in the positive pole active material layer and the negative pole active material layer to adsorb and compact each other.

[0031] like Figure 4 As shown, the negative pole internal magnetic field structure (S pole) located inside the dielectric layer and the positive pole external magnetic field structure (N pole) located outside the dielectric layer form a magnetic field from outside to inside. Since the nitrogen and sulfur functionalized carbon foam magnetic microspheres themselves are magnetic, under the action of the magnetic field provided by the magnetic fixed structure, the nitrogen and sulfur functionalized carbon foam magnetic microspheres on the positive active material layer and the negative active material layer have enhanced mutual adsorption forces, and the magnetic microsphere clusters accumulate and are arranged evenly. Therefore, the magnetic microsphere clusters are not easy to fall off and peel off from the active material layer, thereby ensuring the effectiveness of the active material that plays a key role in storing charge in the supercapacitor and avoiding the loss of effective materials, thereby achieving the effect of increasing the number of charge and discharge times of the supercapacitor and extending the service life of the supercapacitor.

[0032] 3. In the lithium battery-supercapacitor hybrid energy storage device described in the present invention, the inductor coil and the lithium battery are first connected in series during connection, and then the inductor coil and the lithium battery group are connected in series to form a first circuit, and then connected in parallel with the supercapacitor group to form a second circuit; the supercircuit and the control circuit are connected in series to form a third circuit, the control circuit is connected to a load electrical equipment, and the third circuit is connected or closed by the control circuit, thereby controlling whether the supercapacitor supplies power to the load electrical equipment.

[0033] The lithium battery-supercapacitor hybrid energy storage device of the present invention uses a supercapacitor as a buffer between the lithium battery and the load electrical equipment. The lithium battery first charges the superbattery, and then the supercapacitor supplies power to the load electrical equipment. The device effectively slows down the heating of the lithium battery caused by the current change and reduces the number of times the lithium battery is charged and discharged through structural improvements, which can improve the safety of the power supply of the device, increase the number of times the lithium battery is charged and discharged, and extend the service life of the battery. Of course, when the lithium battery is out of power, the supercapacitor can also charge the lithium battery, saving the manual time for regular charging and maintenance of the lithium battery.

[0034] 4. In the lithium battery-supercapacitor hybrid energy storage device described in the present invention, an inductor coil connected in series with the lithium battery is added. The inductor coil can slow down the change of lithium battery current, reduce the probability of current mutation, and is safer. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the magnetic fixing structure of the supercapacitor of the present invention;

[0036] Figure 2 A top view of the supercapacitor of the present invention;

[0037] Figure 3 A longitudinal cross-sectional view of the supercapacitor of the present invention;

[0038] Figure 4 for Figure 3 A partial enlarged view of part a;

[0039] Figure 5 This is a circuit diagram of the lithium battery-supercapacitor hybrid energy storage device of the present invention;

[0040] Figure 6 The test circuit diagram of the inductor's suppression effect on current mutation in Example 2;

[0041] Among them, 1 is a lithium battery, 2 is an inductor coil, 3 is a supercapacitor, 4 is a control circuit, 5 is a load electrical equipment, 6 is a power detection device, 100 is a dielectric layer, 111 is a negative electrode conductive substrate, 112 is a positive electrode conductive substrate, 121 is a negative electrode active material layer, 122 is a positive electrode active material layer, 130 is an insulating layer, 210 is a negative electrode internal magnetic field structure, 220 is a positive electrode external magnetic field structure, 230 is a negative electrode lead wire, 240 is a positive electrode lead wire, A is an ammeter, C is a capacitor, D is a diode, S1 is a knife switch 1, S2 is a knife switch 2, R1 is a resistor 1, R2 is a resistor 2, R3 is a resistor 3, R4 is a resistor 4, and PNP is a transistor. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the implementation methods of the present application, not all of the implementation methods; and the structures shown in the accompanying drawings are only schematic and do not represent physical objects. It should be noted that based on these embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0043] The first aspect of the present invention provides a high energy density supercapacitor, the supercapacitor includes a dielectric layer 100, the dielectric layer 100 includes a conductive substrate, an active material layer and an insulating layer arranged in sequence; wherein the active material layer includes nitrogen and sulfur functionalized carbon foam magnetic microspheres as active materials. The energy density of the supercapacitor of the present invention is at least 4.5 kWh / kg, and the charging efficiency is not less than 91%. In some preferred embodiments of the present invention, the active material layer includes nitrogen and sulfur functionalized carbon foam magnetic microspheres as active materials with a mass percentage of not less than 90%.

[0044] The composition and preparation method of the "nitrogen and sulfur functionalized carbon foam magnetic microspheres" described in the present invention can refer to the records of ZL201510359764.4, the entire text of which is incorporated into the present invention. They can also be obtained by purchasing commercially available products.

[0045] Figure 1-4 A specific structure of the supercapacitor described in the present invention is shown, and the supercapacitor includes a dielectric layer 100 and a magnetic fixing structure. The magnetic fixing structure is cylindrical, including a cylindrical negative pole inner magnetic field structure 210 and an annular positive pole outer magnetic field structure 220. The dielectric layer 100 is a hollow ring. The cylindrical negative pole inner magnetic field structure 210, the annular positive pole outer magnetic field structure 220 and the dielectric layer 100 are concentric. The bottom of the cylindrical negative pole inner magnetic field structure 210 and the bottom of the annular positive pole outer magnetic field structure 220 are connected. The dielectric layer is arranged between the negative pole inner magnetic field structure and the positive pole outer magnetic field structure. The magnetic field formed by the negative pole inner magnetic field structure and the positive pole outer magnetic field structure can cause the nitrogen and sulfur functionalized carbon foam magnetic microspheres in the positive pole active material layer and the negative pole active material layer to adsorb and compact each other. Figure 4 As shown, in the dielectric layer 100, the conductive substrate includes a positive conductive substrate 112 and a negative conductive substrate 111, and the active material layer includes a positive active material layer 122 and a negative active material layer 121. The positive active material layer 122 and the negative active material layer 121 can carry positive charge and negative charge respectively; in the dielectric layer, the positive conductive substrate 112, the positive active material layer 122, the insulating layer 130, the negative active material layer 121 and the negative conductive substrate 111 are arranged in sequence.

[0046] In the present invention, the material of the conductive substrate includes but is not limited to corroded aluminum foil and / or polyvinylidene fluoride. In the present invention, the active material layer is composed of nitrogen and sulfur functionalized carbon foam magnetic microspheres and adhesives in a mass percentage of 90-95%:5-10%. In the present invention, the insulating layer includes insulating materials and adhesives, and the insulating materials include but are not limited to graphite, graphene, and polyimide glue; in some preferred embodiments of the present invention, the insulating layer includes graphite, polyimide glue and adhesives in a mass percentage of 75-80%:4-10%:5-10%. In some preferred embodiments of the present invention, the adhesive is selected from a mixed water-soluble binder including styrene-butadiene rubber and sodium carboxymethyl cellulose. In some specific embodiments of the present invention, the negative pole internal magnetic field structure and the positive pole external magnetic field structure are magnets or electromagnets.

[0047] In some preferred embodiments of the present invention, the method for preparing the dielectric layer of the supercapacitor comprises the following steps:

[0048] (1) mixing nitrogen and sulfur functionalized carbon foam magnetic microspheres and a binder with water and stirring to obtain a first mixture;

[0049] The binder is mixed with water to form a slurry, and the insulating material is gradually added to the slurry to obtain a second mixture;

[0050] (2) coating the first mixture on the surface of the positive electrode conductive substrate and the negative electrode conductive substrate, respectively, and drying to obtain a positive electrode conductive substrate-active material layer and a negative electrode conductive substrate-active material layer;

[0051] (3) The second mixture is coated between the positive electrode conductive substrate-active material layer and the negative electrode conductive substrate-active material layer, and dried to form a dielectric layer in which the positive electrode conductive substrate, the positive electrode active material layer, the insulating layer, the negative electrode active material layer and the negative electrode conductive substrate are arranged in sequence.

[0052] Preferably, in step (1), the stirring rate is 1500-2000 r / min and the stirring time is more than 5 h.

[0053] The capacitors made by the above method can improve the energy density under the condition of the same withstand voltage; the capacity of capacitors of the same size can be increased by 20% to 25%;

[0054] A second aspect of the present invention provides a lithium battery-supercapacitor hybrid energy storage device, comprising the supercapacitor described in the above technical solution. Figure 2A schematic diagram of a circuit structure is shown, including a lithium battery 1, an inductor 2, a super capacitor 3, a control circuit 4, a load electrical device 5 and a power detection device 6. The lithium battery 1, the inductor 2 and the super capacitor 3 are connected in series to form a first circuit, and the inductor 2 is used to delay the current change of the lithium battery 1; the first circuit is connected in parallel with the super capacitor 3 to form a second circuit; the super capacitor 3 is connected in series with the control circuit 4 to form a third circuit, and the control circuit 4 can control the load electrical device 5 to connect or disconnect. The first circuit also includes a power detection device 6 connected in parallel with the lithium battery 1, which is used to detect the power of the lithium battery.

[0055] In the present invention, the lithium battery 1 is used to store and supply energy. In some preferred technical solutions of the present invention, the lithium battery is a lithium iron phosphate battery. In the present invention, the inductor 2 is used to buffer the current entering and released by the lithium battery, reduce the probability of current mutation, and improve the safety of the device. In some preferred technical solutions of the present invention, the number of winding turns of the inductor is at least 20 turns, and more preferably 20 to 22 turns. In the present invention, the supercapacitor 3 has an extremely high energy density, wherein the electrodes of the supercapacitor are made of active materials including nitrogen and sulfur functionalized carbon foam magnetic microspheres. The electrodes made of this material have the advantages of large area and small electrode distance, and can be farad-level. Generally, the capacitance range can reach 1-100F, the voltage rating is 2.7V, and the operating temperature range is -40°C to 65°C. In some preferred solutions of the present invention, the energy density of the supercapacitor is 4.5 kWh / kg and the charging efficiency is 91% to 93%.

[0056] In the present invention, the control circuit 4 is used to control whether the supercapacitor supplies power to the load electrical device 4; in a specific embodiment, the control circuit can be a switch. In the present invention, the power detection device 6 is used to detect the power of the lithium battery so as to more clearly control the charging and discharging process.

[0057] The present invention also provides an electric forklift, comprising the lithium battery-supercapacitor hybrid energy storage device described in the aforementioned technical solution. Supercapacitors and lithium batteries are both electrical energy storage systems. A significant advantage of lithium battery technology is that it has a very high specific energy or energy density, which can store energy for later use. But supercapacitors, in which electrical energy is stored electrostatically. Supercapacitors use dielectrics or insulators between their plates to separate the positive (+ve) and negative (-ve) charges accumulated on each side of the plate. It is this separation that enables the device to store energy and release it quickly. It can basically capture static electricity for future use. The most significant advantage of doing this is that a 3V capacitor today will still be a 3V capacitor in 15-20 years. In contrast, lithium-ion batteries may lose voltage capacity over time and repeated use. In general, supercapacitors are considered to have the greatest application potential in hybrid transportation. For example, if a supercapacitor is used in a car, the kinetic energy can be converted into electricity and stored in the supercapacitor during the car's deceleration, and then the energy in the supercapacitor can be released to drive the car when accelerating, which can save the car's energy consumption. Compared with lithium batteries, supercapacitors have greater power and almost no problems with capacity decay and life. This supercapacitor uses frequent charging and discharging to make up for the problem of insufficient energy density of supercapacitors. And because supercapacitors only absorb lower currents for a few minutes at a time, they put less pressure on the power grid. Lithium batteries have a much higher energy density than supercapacitors. This means that batteries are more suitable for applications with higher energy density, such as applications where the device needs to run for a long time after a single charge. On the other hand, supercapacitors have a much higher power density than batteries. This makes it very suitable for high-power consumption applications such as powering electric vehicles.

[0058] Table 1

[0059]

[0060] As can be seen from Table 1, the service life of supercapacitors is also much longer than that of batteries. Ordinary lithium batteries can handle about 2000-3000 charge and discharge cycles, while supercapacitors can usually maintain more than 1 million charge and discharge cycles, so it can save a lot of materials and costs.

[0061] Supercapacitors have not yet been widely used in electrical technology. But as graphene becomes more widely used, supercapacitors are slowly establishing themselves as an important player in hybrid power technology. Supercapacitors can play a role in the manufacture of lithium-ion batteries, and the supercapacitors disclosed in this invention have higher energy density and are more useful for a longer period of time.

[0062] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0063] Example 1

[0064] like Figure 1 A lithium battery-supercapacitor hybrid energy storage device shown includes a lithium iron phosphate battery 1, an inductor 2, a supercapacitor 3, a control circuit 4, a load electrical device 5, and a power detection device 6. The lithium battery 1, the inductor 2, and the supercapacitor 3 are connected in series to form a first circuit, and the inductor 2 is used to delay the current change of the lithium battery 1; the first circuit is connected in parallel with the supercapacitor 3 to form a second circuit; the supercapacitor 3 is connected in series with the control circuit 4 to form a third circuit, and the control circuit 4 can control the load electrical device 5 to connect or disconnect. The first circuit also includes a power detection device 6 connected in parallel with the lithium battery 1, which is used to detect the power of the lithium battery.

[0065] Super Electrode 3 Figure 1-4 As shown, the supercapacitor includes a dielectric layer 100 and a magnetic fixed structure. The magnetic fixed structure is cylindrical, including a cylindrical negative pole inner magnetic field structure 210 and an annular positive pole outer magnetic field structure 220. The dielectric layer 100 is a hollow ring. The cylindrical negative pole inner magnetic field structure 210, the annular positive pole outer magnetic field structure 220 and the dielectric layer 100 are concentric. The bottom of the cylindrical negative pole inner magnetic field structure 210 and the bottom of the annular positive pole outer magnetic field structure 220 are connected. The dielectric layer is arranged between the negative pole inner magnetic field structure and the positive pole outer magnetic field structure. The magnetic field formed by the negative pole inner magnetic field structure and the positive pole outer magnetic field structure can cause the nitrogen and sulfur functionalized carbon foam magnetic microspheres in the positive pole active material layer and the negative pole active material layer to adsorb and compact each other. As shown in FIG. Figure 4 As shown, in the dielectric layer 100, the conductive substrate includes a positive conductive substrate 112 and a negative conductive substrate 111, and the active material layer includes a positive active material layer 122 and a negative active material layer 121. The positive active material layer 122 and the negative active material layer 121 can carry positive charge and negative charge respectively; in the dielectric layer, the positive conductive substrate 112, the positive active material layer 122, the insulating layer 130, the negative active material layer 121 and the negative conductive substrate 111 are arranged in sequence.

[0066] The dielectric layer 100 is prepared according to the following method:

[0067] (1) nitrogen- and sulfur-functionalized carbon foam magnetic microspheres and an adhesive are loaded in a weight percentage of 90-95%:5-10%, deionized water is added according to 40% of the total weight of the two, and the mixture is stirred at 1500-2000 r / min for 5 hours to obtain a first mixture;

[0068] Weighing polyimide glue and graphite in a mass percentage of 75-80%:4-10%:5-10% and mixing them, preparing the adhesive into a slurry with water, and gradually adding the mixture of polyimide glue and graphite to obtain a second mixture;

[0069] The adhesive is a mixed water-soluble adhesive of BR (styrene-butadiene rubber) and CMC-N (sodium carboxymethyl cellulose).

[0070] (2) coating the first mixture on the surface of the positive electrode conductive substrate 112 and the negative electrode conductive substrate 111, respectively, with a coating thickness of 0.2 to 0.25 mm, and drying at 80 to 90° C. for 5 h to obtain a positive electrode conductive substrate-active material layer and a negative electrode conductive substrate-active material layer;

[0071] The positive electrode conductive substrate and the negative electrode conductive substrate are corroded aluminum foil, which serves as a carrier for carrying active materials.

[0072] (3) The second mixture is coated between the positive electrode conductive substrate-active material layer and the negative electrode conductive substrate-active material layer with a coating thickness of 0.02 to 0.03 μm, and dried at 80 to 95° C. for more than 5 hours to obtain a dielectric layer 100 in which the positive electrode conductive substrate, the positive electrode active material layer, the insulating layer, the negative electrode active material layer and the negative electrode conductive substrate are arranged in sequence.

[0073] (4) Cut into required size according to the design requirements of the capacitor.

[0074] (5) Rivet the electrode slices according to the capacity and voltage of the designed model. Rivet the negative lead wire 230 and the positive lead wire 240 respectively. The outer diameters of the negative lead wire 230 and the positive lead wire 240 are both 0.3-0.5 mm and the lengths are both 5-8 mm. When riveting, glue can be used to protect the riveted parts.

[0075] (6) The outer diameter of the winding core is determined according to the outer diameter of the designed capacitor. During the winding process, the electrode sheets are separated by a PDFE film of 0.02 to 0.03 mm.

[0076] (7) The rolled cylindrical capacitor core is baked for more than 12 hours (85-95° C.), cooled for 24 hours, and then immersed in electrolyte for more than 1 hour to obtain a ring-shaped dielectric layer 100.

[0077] The annular dielectric layer 100 is installed in a cylindrical magnetic fixing structure ( Figure 1 ), and then put it into the capacitor shell and inject glue for packaging, so that the capacitor is made. A super capacitor with high energy density is obtained.

[0078] The supercapacitor manufactured by the above method can improve the energy density under the condition of the same withstand voltage; the capacity of the supercapacitor of the same volume is increased by 20% to 25%.

[0079] Example 2

[0080] In order to determine the effect of inductance on the suppression of current changes, the Figure 2 The test circuit for the inductor's effect on current mutation suppression is shown, and the assembly of the relevant structure is in accordance with the description of Example 1.

[0081] During the experiment, the knife switches S1 and S2 are in the disconnected state. First, the charging power supply is turned on, and then the knife switch S1 is closed. The power is turned on for 3 to 5 minutes, and the current data is read through the ammeter A with a data recording function. Then the knife switch S1 is disconnected, and the knife switch S2 is closed. The power is turned on for 3 to 5 minutes, and the current data is read through the ammeter A with a data recording function. In the experiment, a 48V lithium battery pack is selected, and a 1mH inductor is selected. The closed switches S1 and S2 are measured, and the change of the current in the charging circuit over time is as follows Figure 6 As shown in the data, it can be seen that due to the effect of the inductor in suppressing the sudden change of current, the rate of change of the current in the charging circuit over time becomes significantly smaller. The pulsation of the current in the charging circuit becomes smaller.

[0082] The results are shown in Table 2. It can be seen that due to the effect of the inductor in suppressing the sudden change of current, the rate of change of the current in the charging circuit over time is significantly reduced. The pulsation of the current in the charging circuit is reduced. Therefore, the structural design of the device described in the present invention can effectively reduce the current change in the circuit, which helps to improve the safety and service life of the lithium battery.

[0083] Table 2

[0084] Time (milliseconds) Current value when S1 is closed (A) Current value when S2 is closed (A) 5 12.865 16.352 10 12.572 14.786 15 12.355 13.698 20 11.586 12.849 25 11.245 11.362 30 10.896 11.103

[0085] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A supercapacitor with high energy density, characterized in that: The supercapacitor includes a dielectric layer, which includes a conductive substrate, an active material layer and an insulating layer arranged in sequence; The active material layer includes nitrogen and sulfur functionalized carbon foam magnetic microspheres as active materials.

2. The supercapacitor according to claim 1, characterized in that: The conductive substrate is selected from corroded aluminum foil and / or polyvinylidene fluoride; the active material layer is composed of nitrogen and sulfur functionalized carbon foam magnetic microspheres and adhesives in mass percentages of 90-95%:5-10%; the insulating layer includes graphite, polyimide glue and adhesives in mass percentages of 75-80%:4-10%:5-10%.

3. The supercapacitor according to claim 2, characterized in that: The adhesive is selected from a mixed water-soluble adhesive including styrene-butadiene rubber and sodium carboxymethyl cellulose.

4. The supercapacitor according to claim 1, characterized in that: The active material layer comprises nitrogen and sulfur functionalized carbon foam magnetic microspheres with a mass percentage of not less than 90% as active materials.

5. The supercapacitor according to claim 1, characterized in that: The conductive substrate includes a positive electrode conductive substrate and a negative electrode conductive substrate, and the active material layer includes a positive electrode active material layer and a negative electrode active material layer; In the dielectric layer, the positive electrode conductive substrate, the positive electrode active material layer, the insulating layer, the negative electrode active material layer and the negative electrode conductive substrate are arranged in sequence.

6. The supercapacitor according to claim 5, characterized in that: The method for preparing the dielectric layer of the supercapacitor comprises the following steps: (1) mixing nitrogen and sulfur functionalized carbon foam magnetic microspheres and a binder with water and stirring to obtain a first mixture; The binder is mixed with water to form a slurry, and the insulating material is gradually added to the slurry to obtain a second mixture; (2) coating the first mixture on the surface of the positive electrode conductive substrate and the negative electrode conductive substrate, respectively, and drying to obtain a positive electrode conductive substrate-active material layer and a negative electrode conductive substrate-active material layer; (3) The second mixture is coated between the positive electrode conductive substrate-active material layer and the negative electrode conductive substrate-active material layer, and dried to form a dielectric layer in which the positive electrode conductive substrate, the positive electrode active material layer, the insulating layer, the negative electrode active material layer and the negative electrode conductive substrate are arranged in sequence.

7. The supercapacitor according to claim 6, characterized in that: In step (2), the coating thickness of the first mixture is 0.2 to 0.25 mm, the drying temperature is 80 to 90° C., and the drying time is more than 5 hours; In step (3), the coating thickness of the second mixture is 0.02-0.03 μm, the drying temperature is 80-90° C., and the drying time is more than 5 hours.

8. The supercapacitor according to any one of claims 5 to 7, characterized in that: The supercapacitor also includes a magnetic fixed structure, which includes a negative pole internal magnetic field structure and a positive pole external magnetic field structure. The dielectric layer is arranged between the negative pole internal magnetic field structure and the positive pole external magnetic field structure. The magnetic field formed by the negative pole internal magnetic field structure and the positive pole external magnetic field structure can cause the nitrogen and sulfur functionalized carbon foam magnetic microspheres in the positive pole active material layer and the negative pole active material layer to adsorb and compact each other.

9. The supercapacitor according to claim 8, characterized in that: The magnetic fixing structure is cylindrical, including a cylindrical negative pole inner magnetic field structure and an annular positive pole outer magnetic field structure; the dielectric layer is a circular ring; The inner magnetic field structure of the cylindrical negative pole, the outer magnetic field structure of the annular positive pole and the dielectric layer are concentric; The bottoms of the cylindrical negative pole inner magnetic field structure and the annular positive pole outer magnetic field structure are connected.

10. The supercapacitor according to any one of claims 1 to 7, characterized in that: The energy density of the supercapacitor is at least 4.5 kWh / kg and the charging efficiency is not less than 91%.

11. A lithium battery-supercapacitor hybrid energy storage device, characterized in that: Including lithium batteries, inductors, supercapacitors, control circuits and load electrical equipment; The lithium battery, the inductor coil and the supercapacitor are connected in series to form a first circuit, and the inductor coil is used to delay the current change of the lithium battery; The first circuit is connected in parallel with the super capacitor to form a second circuit; The supercapacitor and the control circuit are connected in series to form a third circuit. The control circuit is connected to the load electrical equipment and can control the load electrical equipment to be connected or disconnected.

12. The lithium battery-supercapacitor hybrid energy storage device according to claim 11, characterized in that: The lithium battery is a lithium iron phosphate battery.

13. The lithium battery-supercapacitor hybrid energy storage device according to claim 11, characterized in that: The first circuit also includes a power detection device connected in parallel with the lithium battery, which is used to detect the power of the lithium battery.

14. The lithium battery-supercapacitor hybrid energy storage device according to claim 11, characterized in that: The number of winding turns of the inductor coil is at least 20 turns.

15. The lithium battery-supercapacitor hybrid energy storage device according to any one of claims 11 to 14, characterized in that: The supercapacitor is the supercapacitor according to any one of claims 1 to 10.

16. An electric forklift, characterized in that: A lithium battery-supercapacitor hybrid energy storage device comprising any one of claims 11-15.

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