CN104466259A - Preparation method of single hybrid energy storage unit based on lithium ion capacitor and lithium battery - Google Patents

Abstract

A method for preparing a hybrid energy storage monomer based on a lithium ion capacitor and a lithium battery, characterized in that: the energy storage monomer pole piece unit is composed of a lithium positive electrode, a carbon positive electrode and a carbon negative electrode, and the current collectors of the electrodes are all perforated The structure, lithium positive electrode, carbon positive electrode and carbon negative electrode are all led out by tabs, and the energy storage unit is composed of multiple pole piece units according to the capacity design, and a non-aqueous organic solvent containing lithium ions that can move freely is used as the electrolyte ;By connecting the lithium positive electrode and the carbon negative electrode, the lithium positive electrode is charged to the carbon negative electrode, and the lithium ions in the lithium positive electrode are embedded in the carbon negative electrode through an electrochemical reaction; Realize the high-rate performance of supercapacitors and the high-capacity performance of lithium-ion batteries. The method of the invention is simple, practical and easy to produce, realize and popularize.

Description

A preparation method based on lithium ion capacitor and lithium battery hybrid energy storage monomer

technical field

The invention relates to a method for preparing a hybrid energy storage monomer based on a lithium ion capacitor and a lithium battery. The energy storage monomer is composed of a lithium positive electrode, a carbon positive electrode, a carbon negative electrode and a non-aqueous organic solvent containing freely moving lithium ions. In one structural unit, the high-rate characteristics of supercapacitors and the high-capacity characteristics of lithium-ion batteries can be realized at the same time.

Background technique

High energy density, high power density, wide temperature range and long cycle life are the development direction and scientific research goals of new chemical power sources.

Lithium-ion batteries and supercapacitors represent the development direction of new chemical power sources. Among all commercial chemical power sources, lithium-ion batteries are characterized by high energy density.

The main application fields of lithium-ion batteries include energy type (mainly used in digital products represented by mobile phones and mobile computers), and power type (electric tools, hybrid vehicles, electric bicycles, electric vehicles). With the gradual development of material technology and battery design technology, lithium-ion batteries are more widely used in the field of power. Repeated deintercalation is used to realize the energy storage process, so the capacity of lithium batteries decays rapidly during long-term high-rate cycling, and the capacity decays quickly under low temperature conditions.

Supercapacitor is a new type of energy device. Traditional supercapacitors use the electric double layer formed on the surface of positive and negative carbon electrode materials to realize the energy storage process. The energy density of supercapacitors depends on the specific capacitance and stable potential of the electrode materials. window.

Since the supercapacitor realizes the energy storage process by forming an electric double layer on the electrode surface, the structure of the electrode material collapses due to the absence of ions intercalating and deintercalating in the bulk phase of the electrode material. Therefore, compared with lithium-ion batteries, supercapacitors have Features of high cycle performance, high power characteristics and wide temperature range. Since the energy storage method of the supercapacitor is electric double layer energy storage, the ion concentration inside the electrode material is very low, and the potential window of the supercapacitor is low (1-2.7V), which determines that the energy density of the supercapacitor is very low, about How to improve the energy density of supercapacitors has become a research hotspot in recent years.

In order to increase the energy density of supercapacitors, it is mainly achieved by increasing the specific capacitance of the electrode material and increasing the stable potential window of the capacitor, but metal oxide electrodes with high specific capacitance (such as rhodium oxide, manganese oxide and cobalt oxide) are usually Energy storage needs to be realized in an aqueous solution system, so the improvement of the potential window is limited; and the use of an asymmetric capacitor (one pole metal oxide, the other pole activated carbon material) improves the energy density of the supercapacitor to a certain extent, but Since the increase in the stable potential window is still relatively limited, and at the same time due to the instability of the structure of the metal oxide electrode during the reaction process, the cycle life is greatly reduced.

Lithium-ion capacitors are asymmetric capacitors with different charging and discharging principles between the positive and negative electrodes. Combination, and at the same time, lithium ions are added to the negative electrode, which greatly improves the energy density of the capacitor.

The lithium-ion capacitor mentioned in the patent uses a high specific surface area carbon material as the positive electrode and graphite as the negative electrode to prepare a lithium-ion capacitor. In the capacitor, lithium metal sheets are used to pre-embed graphite into the graphite. The maximum potential between the positive and negative electrodes of the lithium capacitor window up to 4.35V. However, due to the instability and easy oxidation of lithium sheets, it is easy to chemically react with moisture and oxygen in the air. Therefore, when introducing lithium electrodes, it needs to be carried out in an anhydrous and oxygen-free external environment, which requires industrial production environment. higher. As a result, the assembly process of the capacitor is very difficult.

For new energy storage devices, it is expected to have the characteristics of high energy density, high power characteristics, long life and wide temperature range. Batteries are "externally paralleled", lithium-ion batteries are used when energy storage is required, and supercapacitors are used when rate discharge is required, but this multi-functionality cannot be realized in a single energy storage unit. The implementation of external parallel connection will make the protection circuit design more complicated.

Contents of the invention

In view of the problems existing in the background technology, the present invention proposes a method for preparing a hybrid energy storage monomer based on a lithium ion capacitor and a lithium battery. The functions of a lithium-ion battery and a lithium-ion supercapacitor are simultaneously realized in one unit structure. And through the easy-to-process lithium cathode material sheet, the lithium is electrochemically inserted into the negative electrode to effectively realize the assembly of the energy storage device.

The technical scheme of the technical problem to be solved by this invention is as follows:

The hybrid energy storage monomer of the present invention is composed of a plurality of pole piece units and lithium-containing organic electrolyte, and the pole piece unit is composed of a lithium positive electrode, a carbon positive electrode and a carbon negative electrode; the lithium positive electrode is a lithium ion battery positive electrode material, and the material It can freely deintercalate lithium compounds and give lithium ions. The carbon positive pole is a high specific surface area carbon material, which can form an electric double layer. The carbon negative pole is a layered carbon material, which can freely accept lithium ions.

The three electrodes of the pole piece unit respectively have a collector, and the collector has a hole through which the front and back sides pass through, and the diameter of the hole is between 100 microns and 1 mm.

The pole piece unit is composed of a piece of lithium positive electrode, a piece of carbon positive electrode and a piece of carbon negative electrode. The current collectors formed by the collectors of the positive and negative electrodes adopt a perforated structure, that is, there are evenly distributed pole pieces on each pole piece. small holes; and the lithium positive electrode, carbon positive electrode and carbon negative electrode all have lugs, and the energy storage unit is designed to be stacked by a plurality of pole piece units according to the capacity.

The perforated collectors of the three electrodes of the pole piece unit, the collectors of the lithium positive electrode and the carbon positive electrode are made of aluminum foil, and the collectors of the carbon negative electrode are made of copper foil.

The deintercalable lithium compound in the lithium positive pole piece is one or a combination of lithium cobalt oxide, nickel cobalt lithium manganate ternary material, and lithium iron phosphate.

The high specific surface area carbon material in the carbon positive electrode sheet is one or more mixtures of activated carbon, carbon nanotubes, graphene, and carbon aerogel.

The layered carbon material of the carbon negative electrode is one or a combination of natural graphite, artificial graphite, hard carbon material and soft carbon material.

The lithium-containing organic electrolyte, its electrolyte contains hexafluorophosphorous lithium, tetraethylamine tetrafluoroborate materials, the solvent is one or more of propylene carbonate, dimethyl carbonate, ethylene carbonate, acetonitrile kind of mix.

The preparation method of technical problem to be solved by this invention is as follows:

First, connect the lithium positive electrode and the carbon negative electrode and make the lithium ions in the positive electrode intercalate into the negative electrode by applying a voltage;

Secondly, after the lithium ion intercalation process, the voltage drop between the lithium positive electrode and the negative electrode is 3.8-4.2V, and the potential difference between the activated carbon positive electrode and the negative electrode is 2.5-3.0V;

Third, the working voltage range between lithium positive and negative electrodes is 2.8-4.2V, and the working voltage range between activated carbon positive and negative electrodes is 0-4.2V;

Fourth, connect the lithium positive and negative electrodes to realize high energy density energy storage of lithium batteries, and connect the activated carbon positive and negative electrodes to realize high-rate discharge and low-temperature discharge of lithium-ion capacitors.

When the hybrid energy storage single device is used in the field of energy storage, the lithium positive electrode and the carbon negative electrode are connected, and the working voltage range is 2.6-4.2V, which can be used as a lithium ion battery; when the hybrid energy storage single device is used for large When the current is discharged or used under low temperature conditions, the carbon positive electrode and the carbon negative electrode are connected, and it can be used as a lithium ion capacitor.

The beneficial effects of the present invention are as follows:

The present invention simultaneously realizes the functions of a lithium ion battery and a lithium ion supercapacitor in a unit structure, and the energy storage unit can select an energy release mode according to a specific use occasion.

The invention adopts the lithium positive electrode material to realize pre-intercalation of lithium on the carbon negative electrode, and the operation is simple, and the possibility of engineering realization is greater.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

(The same parts in each figure have the same number)

Fig. 1 is a schematic diagram of pole piece unit structure in the present invention;

Fig. 2 is a schematic structural diagram of the hybrid energy storage monomer of the present invention;

Fig. 3 is the discharge curve diagram of connecting lithium positive pole and carbon negative pole of the present invention;

Fig. 4 is the charging and discharging curve diagram of connecting the carbon positive electrode and the carbon negative electrode of the present invention;

Fig. 5 is a diagram of the potential change of the electrode sheet during the lithium positive electrode to the carbon negative electrode intercalation process of the present invention;

Fig. 6 is a cycle diagram of connecting the carbon positive electrode and the carbon negative electrode of the present invention.

In the figure: 1. Lithium positive electrode, 2. Carbon positive electrode, 3. Carbon negative electrode, 4. Carbon positive electrode, 5. Lithium positive electrode, 6. Diaphragm, 7. Tab, 8. Lithium metal sheet, 9. Pole hole.

Detailed ways

Below in conjunction with the accompanying drawings, the essence and technical characteristics of the present invention will be further described in detail with specific embodiments, but the present invention is not limited to the described embodiments.

Embodiment one

Production of lithium cathode sheet: Based on mass, lithium cobaltate, conductive agent and binder are mixed in a ratio of 95:2:3 to make a slurry, and then coated on aluminum foil with an area density of 2.3g /dm ² , after drying (120°C), rolling, cutting into pieces, and 24h vacuum drying (120-130°C) to make positive electrode sheets.

Production of carbon positive plate: Based on mass, lithium cobalt oxide, conductive agent and binder are mixed according to the ratio of 95:2:3, adjusted to make a slurry, and then coated on aluminum foil. The surface capacity is designed to be 2.0g/ dm ² , after drying (120°C), rolling, cutting into pieces, and 24h vacuum drying (120-130°C) to make positive electrode sheets.

Production of carbon negative plate: Based on the mass, artificial graphite, conductive agent and binder are mixed according to the ratio of 96:3:1 to make a slurry, and then coated on the copper foil, the surface capacity is designed to be 1.1g/ dm ² , after drying (120°C), rolling, cutting into pieces, and 24h vacuum drying (120-130°C) to make negative electrode sheets.

The cut lithium positive electrode, carbon positive electrode, and carbon negative electrode are punched with special equipment, so that the small holes of the pole piece are evenly distributed on each pole piece. The purpose of punching is to allow lithium ions to pass freely between the pole pieces without being blocked. The punching standard should be as many and dense as possible without damaging the pole piece.

Assemble the perforated pole pieces. The assembly method adopts the method of stacking sheets. First, put a lithium positive electrode, then a carbon positive electrode, and finally a carbon negative electrode. The sheets are separated by a diaphragm; then a metal lithium sheet is added between the graphite and the activated carbon as The reference electrode is shown in FIG. 1 , and the battery cells are formed after the pole piece units are stacked, and the layout schematic diagram is shown in FIG. 2 . Check it for shorts with a multimeter.

The assembled material is packaged on the packaging machine with the outer packaging. When packaging, pay attention to leaving an opening to facilitate the injection of electrolyte in the future.

Put the encapsulated pole pieces into an oven for vacuum baking at 110 degrees Celsius to remove moisture.

The prepared lithium ion capacitor is injected into the electrolytic solution of lithium hexafluorophosphorus and tetraethylammonium tetrafluoroborate at a ratio of 1:1, and the solvent is acetocyanide.

Connect the lithium positive electrode and the carbon negative electrode to charge, and the charging voltage ends at 4.2V.

Embodiment two

The production of lithium positive electrode sheet: based on the quality, mix nickel-cobalt lithium manganate, conductive agent and binder according to the ratio of 95:2:3, adjust it into a slurry, and then coat it on the aluminum foil. The surface density is designed as 2.3g/dm ² , after drying (120°C), rolling, cutting into pieces, and 24h vacuum drying (120-130°C) to make positive electrode sheets.

Production of carbon positive electrode sheet: Based on the mass, mix activated carbon, conductive agent and binder according to the ratio of 80:10:10 to make a slurry, and then coat it on the aluminum foil, and the surface density is designed to be 2.0g/dm ^2. After drying (120°C), rolling, cutting into pieces, and 24h vacuum drying (120-130°C) to make a carbon positive electrode sheet.

Production of carbon negative electrode sheet: Based on the mass, mix natural graphite, conductive agent and binder according to the ratio of 96:3:1 to make a slurry, and then coat it on the copper foil. The surface capacity is designed to be 1.1g/ dm ² , after drying (120°C), rolling, cutting into pieces, and 24h vacuum drying (120-130°C) to make negative electrode sheets.

The cut positive and negative electrodes lithium cobalt oxide, activated carbon and graphite are perforated. The purpose of punching holes is to allow lithium ions to pass freely between the pole pieces without being blocked. The punching standard should be as many and dense as possible without damaging the pole pieces.

The assembly and liquid injection methods of the energy storage unit are the same as those in the first embodiment.

Embodiment Three

The three strings of energy storage monomers prepared according to Example 1 are used as a unit group, and after adding a charging protection board and a casing, they are prepared into a power supply component. Connecting the lithium positive electrode and the carbon negative electrode can be used as an ordinary lithium battery, such as for small electrical appliances. It can also be used for emergency starting of cars at room temperature. However, under low temperature conditions, it is impossible to discharge a large current between the lithium positive electrode and the carbon negative electrode. At this time, connecting the carbon positive electrode and the carbon negative electrode can also achieve high current. Discharge, start the car.

Claims (9)

1., based on a preparation method for lithium-ion capacitor and lithium battery hybrid energy-storing monomer, it is characterized in that:

Described hybrid energy-storing monomer forms by multiple pole piece unit with containing the organic electrolyte of lithium, and pole piece unit is made up of lithium positive pole, carbon positive pole and Carbon anode again; Lithium is anode material for lithium-ion batteries just very, and this material can free removal lithium embedded compound give lithium ion, and carbon is high specific area carbon material just very, and this material can form electric double layer, and Carbon anode is stratiform material with carbon element, and this material freely can accept lithium ion.

2. a kind of preparation method based on lithium-ion capacitor and lithium battery hybrid energy-storing monomer according to claim 1, it is characterized in that: three kinds of electrodes of described pole piece unit have collector electrode respectively, and the hole that collector electrode has positive and negative through, bore dia is between 100 microns of-1mm.

3. a kind of preparation method based on lithium-ion capacitor and lithium battery hybrid energy-storing monomer according to claim 1, it is characterized in that: described pole piece unit is made up of a slice lithium positive pole, a slice carbon positive pole and a slice Carbon anode, the collector that the collector electrode of described positive and negative electrode is formed all adopts perforation structure, on each pole piece, be namely provided with the pole piece aperture be evenly abound with; And lithium positive pole, carbon positive pole and Carbon anode all have lug to draw, described energy storage monomer is laminated by multiple pole piece unit according to amount of capacity design.

4. a kind of preparation method based on lithium-ion capacitor and lithium battery hybrid energy-storing monomer according to claim 2, it is characterized in that: the perforation collector electrode of three kinds of electrodes of described pole piece unit, the current collection very aluminium foil of lithium positive pole and carbon positive pole, the current collection very Copper Foil of Carbon anode.

5. a kind of preparation method based on lithium-ion capacitor and lithium battery hybrid energy-storing monomer according to claim 1, is characterized in that: in described lithium anode pole piece can removal lithium embedded compound be one or more mixing in cobalt acid lithium, cobalt nickel lithium manganate ternary material, LiFePO4.

6. a kind of preparation method based on lithium-ion capacitor and lithium battery hybrid energy-storing monomer according to claim 1, is characterized in that: the high-specific surface area material with carbon element in described carbon anode pole piece is one or more mixing in activated carbon, carbon nano-tube, Graphene, carbon aerogels.

7. a kind of preparation method based on lithium-ion capacitor and lithium battery hybrid energy-storing monomer according to claim 1, is characterized in that: the stratiform material with carbon element of described Carbon anode is one or more mixing in native graphite, Delanium, hard carbon material, soft material with carbon element.

8. a kind of preparation method based on lithium-ion capacitor and lithium battery hybrid energy-storing monomer according to claim 1, it is characterized in that: the described organic electrolyte containing lithium, its electrolyte comprises hexafluoro phosphorus lithium, tetrafluoro boric acid tetraethyl amine material, and solvent is one or more mixing in propene carbonate, dimethyl carbonate, ethylene carbonate, second cyanogen.

9. a kind of preparation method based on lithium-ion capacitor and lithium battery hybrid energy-storing monomer according to claim 1, its method is:

1) lithium positive pole and Carbon anode is first connected also by applying the Lithium-ion embeding negative pole that voltage makes in positive pole;

2) reduce to 3.8-4.2V by voltage between the lithium positive pole after Lithium-ion embeding process and negative pole, the potential difference between activated carbon positive pole and negative pole is 2.5-3.0V;

3) operating voltage range between lithium positive pole and negative pole is 2.8-4.2V, and the operating voltage range between active carbon positive pole and negative pole is 0-4.2V;

4) connect lithium positive pole and negative pole, realize the high-energy-density energy storage of lithium battery, connect activated carbon positive pole and negative pole, realize lithium-ion capacitor high-multiplying power discharge and low temperature discharge.