CN111554959A

CN111554959A - Electrode assembly method for prolonging service life of battery

Info

Publication number: CN111554959A
Application number: CN201910116026.5A
Authority: CN
Inventors: 不公告发明人
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-02-09
Filing date: 2019-02-09
Publication date: 2020-08-18

Abstract

The invention discloses an electrode assembly method for prolonging the service life of a battery, wherein the battery is generally formed by assembling a battery anode material, a short-circuit prevention diaphragm, a battery cathode material and an electrolyte. For the power battery, in order to obtain the energy density as large as possible, the interface current density is required to be uniformly distributed for normal charge and discharge, and the electrode is ensured not to be easily polarized and damaged. According to the invention, a conductive net (the attached figure is a cylindrical lithium battery cross-section structure, a is an aluminum foil, b is a copper foil, c is a battery anode material, d is a porous conductive net, e is a battery diaphragm, and f is a battery cathode material) is inserted between battery cathode interfaces, so that the polarization of the electrode interfaces can be effectively reduced, the electrode interfaces are prevented from being damaged, and the service life of the battery is prolonged.

Description

Electrode assembly method for prolonging service life of battery

Technical Field

The invention belongs to the field of battery energy storage, and particularly relates to protection of a battery electrode diaphragm interface, which prolongs the service life of a battery.

Background

A battery is generally assembled from a battery positive electrode material, a short-circuit prevention separator, a battery negative electrode material, and an electrolyte. For the power battery, in order to obtain the energy density as large as possible, the interface current density is required to be uniformly distributed for normal charge and discharge, and the electrode is ensured not to be easily polarized and damaged. However, if the negative electrode material near the separator protrudes due to the protrusion of the conductive agent or the erosion of the electrolyte, or the current density of the conductive agent at the local part of the interface is too high due to the uneven distribution of the electrode active material, the conductive agent and the insulating adhesive, the current density at the local part of the electrode interface can generate larger current density in the charging and discharging process, so that the electrode side reaction is generated at the interface of the electrode separator, and the electrode is damaged. For example, when the local current density of a commercial lithium battery is too high during charging, lithium dendrite short circuit can be generated on a negative electrode interface, or impurities are caused to generate reaction on an electrode interface, so that the battery electrode and a diaphragm interface are damaged, and the battery is damaged. As with lead batteries, if a negative conductor with a high current density similar to that of a lithium battery appears at the electrode interface, hydrogen ions in the electrolytic cell will be reduced to evolve hydrogen due to the high electron density of the negative conductor, sulfate ions will be reduced to low-price sulfur or sulfur ions, and oxygen is evolved at the positive electrode, so that the battery reaction interface is damaged and the battery is damaged. The invention inserts a conductive net in the battery electrode interface, which can effectively reduce the polarization of the electrode interface, thereby avoiding the damage of the electrode interface and prolonging the service life of the battery.

Disclosure of Invention

In order to protect the damage of the electrode interface of the battery caused by overlarge local current density of the conductive agent, the invention is implemented by the following technical scheme: a conductive net with uniform holes is inserted into the interface of the electrode diaphragm and the electroactive material of the cathode electrode, the thickness of the conductive net is 5nm-500um, the hole size is 5nm-500um, the hole distance is 5 nm-1 cm, and the conductive net is a conductive material with stable electrochemical properties in the charging and discharging process. The current density of the conductive net is uniformly distributed, so that the polarization of an electrode interface is effectively reduced, and the service life of the battery is prolonged.

The invention further improves the scheme as follows:

1. the conductive net can be a porous conductive net made of conductive metal, or carbon material, or other inorganic or organic matter and composite material thereof.

2. The metal material used for preparing the conductive net comprises common inert metal materials such as platinum, gold, silver, iron, copper, aluminum, nickel, zinc, manganese and the like, alloys thereof, various stainless steels and the like.

3. The carbon materials used for preparing the conductive net comprise various conductive carbon materials such as activated carbon, petroleum coke, pyrolytic resin, graphite, carbon nanotubes, carbon 60, graphene, carbon fibers, carbon black, hard carbon and the like.

4. The materials selected for preparing the conductive mesh comprise a composite conductive polymer material and a structural conductive polymer material, such as the composite conductive polymer material: filling high-efficiency conductive particles or conductive fibers in the polymer, wherein the high-efficiency conductive particles or conductive fibers comprise various metal powder, metalized glass fibers, carbon fibers, aluminum fibers, stainless steel fibers, metal fibers of manganese, nickel, chromium and the like; or a structural conductive polymer material: high-conductivity plastics formed by doping conjugated polymers such as poly-p-phenylene sulfide, polypyrrole, polyacetylene, polythiophene, polyquinoline and the like; and a conductive metal chelate: such as polyketone phthalocyanine, charge-transfer type polymer complex: such as polycations and the like; conductive gel: such as silica gel and the like.

5. The electrode assembly method is suitable for various secondary batteries including lithium batteries, potassium batteries, sodium batteries, magnesium batteries, aluminum batteries, lead-acid batteries, nickel-metal hydride batteries and the like.

The invention has the beneficial effects that:

1. according to the invention, the conductive net is inserted between the battery electrode active material and the diaphragm, so that the damage of the battery electrode interface caused by overlarge local current density of the conductive agent is effectively prevented, and the service life of the battery is greatly prolonged.

2. The material for manufacturing the conductive net has the advantages of low price, wide material selection range and low cost.

3. The method for manufacturing the conductive net has various methods, and the electrode is simple and easy to prepare.

4. The battery manufactured by the invention has large charging and discharging current, high charging speed and large discharging capacity.

5. The method for manufacturing the electrode is suitable for various secondary batteries and has wide application range.

Detailed Description

Service life of the lithium battery:

1. assembling the battery with the inserted carbon black: a2016 stainless steel button-type battery case is adopted, lithium iron phosphate is used as a positive electrode material, and commercial graphite is used as a negative electrode material. Preparing electroactive material, PVDF adhesive and carbon black according to the ratio of 80: 10, using 1M lithium iron hexafluorophosphate as electrolyte (solvent is methyl carbonate, ethylene carbonate and dimethyl carbonate of 1: 1), using aluminium foil as positive electrode current collector, using copper foil as negative electrode current collector and using Celgard film as battery diaphragm, using ethyl alcohol to prepare suspension liquid from commercially available carbon black according to the ratio of 1mg/cm²Spraying on the surface of the negative electrode, and vacuum drying to assemble the battery. And (3) battery measurement: after the battery is sealed, the current of 5mA is used, the charging termination voltage is 4V, and the discharging is finishedThe stop voltage is 2V, the battery discharge capacity is basically unchanged when the battery is charged and discharged by over 30000. The discharge capacity and the charge-discharge efficiency are shown in the attached figure 3 of the specification.

2. Battery assembly with stainless steel mesh inserted: a2016 stainless steel button-type battery case is adopted, lithium iron phosphate carbide is taken as a positive electrode material, and commercial graphite is taken as a negative electrode material. The battery is prepared by mixing an electroactive material, a PVDF adhesive and carbon black according to the ratio of 80: 10, taking 1M lithium iron hexafluorophosphate as an electrolyte (the solvent is methyl carbonate, ethylene carbonate and dimethyl carbonate in the ratio of 1: 1), taking an aluminum foil as an anode current collector, taking a copper foil as a cathode current collector, taking a Celgard film as a battery diaphragm, inserting a stainless steel mesh with the thickness of 1um, the aperture of 2um and the hole spacing of 2mm between the battery diaphragm and a cathode, and assembling the battery after vacuum drying. And (3) battery measurement: after the battery is sealed, the current of 5mA, the charge termination voltage is 4V, the discharge termination voltage is 2V, the battery is charged and discharged for over 30000, and the discharge capacity of the battery is basically unchanged. The discharge capacity and the charge-discharge efficiency are shown in the attached figure 4 of the specification.

Drawings

FIG. 1 is a schematic diagram of a button cell (FIG. 1a is a positive electrode material of the cell, FIG. 1b is a battery diaphragm, FIG. 1c is a conductive net, and FIG. 1d is a negative electrode material).

FIG. 2 is a cross-sectional structure of a cylindrical battery (FIG. 2a is an aluminum foil; FIG. 2b is a copper foil; FIG. 2c is a positive electrode material of the battery; FIG. 2d is a porous conductive mesh; FIG. 2e is a battery separator; FIG. 2f is a negative electrode material of the battery);

FIG. 3 shows the discharge capacity and charge-discharge efficiency of the battery with carbon black inserted therein (FIG. 3a is the cycle efficiency%; FIG. 3b is the specific capacity mAh/g).

FIG. 4 shows the discharge capacity and the charge/discharge efficiency of the stainless steel-inserted battery (FIG. 4a shows the cycle efficiency; FIG. 4b shows the specific capacity mAh/g).

Claims

1. In order to protect the damage of the electrode interface of the battery caused by overlarge local current density of the conductive agent, the invention is implemented by the following technical scheme: a conductive net is inserted into the interface of the electrode diaphragm and the electrode electroactive substance, the thickness of the conductive net is 5nm-500um, the size of the holes is 5nm-500um, and the distance between the holes is 5 nm-1 cm. The current density of the conductive net is uniformly distributed, so that the polarization of an electrode interface is effectively reduced, and the service life of the battery is prolonged.

2. An electrode assembly method for extending battery life according to claim 1, wherein: the conductive net can be a porous conductive net made of conductive metal, or carbon material, or other inorganic or organic matter and composite material thereof. Particular protected patents are not listed here.

3. An electrode assembly method for extending battery life according to claim 1, wherein: the thickness of the conductive net is 5nm-500um, the hole size is 5nm-500um, and the hole distance is 5 nm-1 cm.

4. An electrode assembly method for extending battery life according to claim 1, wherein: the metal material used for preparing the conductive net comprises common inert metal materials such as platinum, gold, silver, iron, copper, aluminum, nickel, zinc, manganese and the like, alloys thereof, various stainless steels and the like. Particular protected patents are not listed here.

5. An electrode assembly method for extending battery life according to claim 1, wherein: the carbon materials used for preparing the conductive net comprise various conductive carbon materials such as activated carbon, petroleum coke, pyrolytic resin, graphite, carbon nanotubes, carbon 60, graphene, carbon fibers, carbon black, hard carbon and the like. Particular protected patents are not listed here.

6. An electrode assembly method for extending battery life according to claim 1, wherein: the materials selected for preparing the conductive mesh comprise a composite conductive polymer material and a structural conductive polymer material, such as the composite conductive polymer material: filling high-efficiency conductive particles or conductive fibers in the polymer, wherein the high-efficiency conductive particles or conductive fibers comprise various metal powder, metalized glass fibers, carbon fibers, aluminum fibers, stainless steel fibers, metal fibers of manganese, nickel, chromium and the like; structural conductive polymer material: conjugated polymers such as poly-p-phenylene sulfide, polypyrrole, polyacetylene, polythiophene, polyquinoline and the like form high-conductivity plastics through doping; and a conductive metal chelate: such as polyketone phthalocyanine, charge-transfer type polymer complex: such as polycations and the like; conductive gel: such as silica gel and the like. Particular protected patents are not listed here.

7. An electrode assembly method for extending battery life according to claim 1, wherein: the electrode assembly method is suitable for various secondary batteries including lithium batteries, potassium batteries, sodium batteries, magnesium batteries, aluminum batteries, lead-acid batteries, nickel-metal hydride batteries and the like. Particular protected patents are not listed here.