CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of the priority of Korean Patent Application Nos. 10-2018-0010900, filed on Jan. 29, 2018, and 10-2018-0125529, filed on Oct. 19, 2018, which are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a top insulator for a secondary battery and a method for manufacturing the same, and more particularly, to a secondary battery, which is improved in properties such as heat resistance and chemical resistance and is suppressed in generation of dust during punching, and a top insulator for a secondary battery.

BACKGROUND ART

In general, secondary batteries include nickel-cadmium batteries, nickel-hydrogen batteries, lithium ion batteries, and lithium ion polymer batteries. Such a secondary battery is being applied to and used in small-sized products such as digital cameras, P-DVDs, MP3Ps, mobile phones, PDAs, portable game devices, power tools, E-bikes, and the like as well as large-sized products requiring high power such as electric vehicles and hybrid vehicles, power storage devices for storing surplus power or renewable energy, and backup power storage devices.

In general, in order to manufacture the lithium secondary battery, first, electrode active material slurry is applied to a positive electrode collector and a negative electrode collector to manufacture a positive electrode and a negative electrode. Then, the electrodes are stacked on both sides of a separator to form an electrode assembly. Also, the electrode assembly is accommodated in a battery case, an electrolyte is injected, and then, sealing is performed.

Such a secondary battery is classified into a pouch type secondary battery and a can type secondary battery according to a material of a case accommodating the electrode assembly. In the pouch type secondary battery, an electrode assembly is accommodated in a pouch made of a flexible polymer material having a variable shape. Also, in the can type secondary battery, an electrode assembly is accommodated in a case made of a metal or plastic material having a predetermined shape.

The can type secondary battery is classified into a prismatic type secondary battery in which the case has a polygonal shape and a cylinder type secondary battery in which the battery case has a cylindrical shape according to the shape of the battery case.

FIG.1is a partial cross-sectional view of a cylindrical secondary battery2according to the related art.

In general, as illustrated inFIG.1, the cylindrical secondary battery2includes a cylindrical battery can12, a jelly-roll type electrode assembly13accommodated in the battery can12, a cap assembly11coupled to an upper portion of the battery can12, a beading part14disposed on a front end of the battery can12to mount the cap assembly11, and a crimping part15for sealing the battery can12.

The cap assembly11has a structure in which a top cap111sealing an opening of the battery can12and forming a positive electrode terminal, a PTC element112that interrupts current by increasing resistance when an internal temperature of the battery increases, a safety vent113that interrupts current when an internal pressure of the battery increases due to abnormal current and exhausts an internal gas, a CID gasket114electrically separating the safety vent from a CID filter115except for a specific portion, and the CID filter115to which a positive electrode lead connected to a positive electrode is connected and which interrupts current when a high pressure is generated in the battery, are sequentially stacked.

Also, the cap assembly11is installed on a beading part14of the battery can12in a state of being mounted on a crimping gasket116. Thus, under normal operation conditions, a positive electrode of the electrode assembly13is electrically connected to the top cap111via the positive electrode lead131, the CID filter115, the safety vent113, and the PTC element112.

An insulator26is disposed on each of the upper and lower ends of the electrode assembly13. Here, a top insulator26disposed on the upper end insulates the electrode assembly13from the cap assembly11, and a bottom insulator (not shown) disposed on the lower end insulates the electrode assembly13from a bottom part of the battery can12.

However, in the case of the cylindrical secondary battery2according to the related art, the top insulator is made of a thermoplastic resin such as polyethylene or polypropylene, which has insulating property and electrolyte resistance and is excellent in punching processability. However, the thermoplastic resin has a considerably low melting point of 200° C. to 250° C. Also, there is a problem that when an internal temperature of the secondary battery2increases sharply to exceed 250° C., the top insulator26is melted to cause short circuit. To solve this problem, although a technique of increasing a thickness of the top insulator26has been proposed, there is a problem that capacity and efficiency of the battery are reduced due to a decrease in an internal space of the secondary battery2.

In recent years, a technology has been proposed in which the top insulator26is manufactured by applying phenol, which is a thermosetting resin, to a glass fiber fabric. However, a melting point of phenol itself is very low at a temperature of 40° C., and even if it is applied to the glass fiber fabric, there is a problem that a mass decreases by being oxidized into carbon dioxide or carbon monoxide at a temperature of 600° C. Also, when the glass fiber fabric is coated with phenol and then punched in a round disc shape, a large amount of dust is generated. Thus, it is difficult to continuously produce the product, resulting in a decrease in production amount and an increase in manufacturing cost.

DISCLOSURE OF THE INVENTION

Technical Problem

To solve a problem to be solved, an object of the present invention is to provide a secondary battery, which is improved in properties such as heat resistance and chemical resistance and is suppressed in generation of dust during punching, and a top insulator for a secondary battery.

The objects of the present invention are not limited to the aforementioned object, but other objects not described herein will be clearly understood by those skilled in the art from descriptions below.

Technical Solution

To solve the above problem, a top insulator for a case of a secondary battery, according to an embodiment of the present invention includes: a glass fiber including crossed weft yarns and warp yarns of raw yarns of the glass fiber; and silicone rubber on at least one surface of the glass fiber.

Also, the silicone rubber may include: a first silicone rubber attached to the glass fiber raw yarns; and a second silicone rubber in a pore between the glass fiber raw yarns.

Also, the glass fiber raw yarns may cross each other in a shape in which the glass fiber raw yarns are perpendicular to each other, and wherein the second silicone rubber may be in the pore between the glass fiber raw yarns that are perpendicular to each other.

Also, the top insulator may have a same thickness as the glass fiber.

Also, the silicone rubber may include: a first silicone rubber applied to at least one surface of the glass fiber; and a second silicone rubber applied to the first silicone rubber.

Also, the first silicone rubber may be stacked on at least one surface of the glass fiber, and wherein the second silicone rubber may be stacked on the first silicone rubber.

Also, the silicones rubber may be stacked on at least one surface of the glass fiber.

Also, the glass fiber may have a disc shape.

Also, the silicone rubber may be applied to all surfaces of the glass fiber.

Also, the glass fiber may have a composition ratio in the top insulator of 70 wt % to 80 wt %, and wherein the silicone rubber may have a composition ratio in the top insulator of 20 wt % to 30 wt %.

Also, the silicone rubber may include a silicone polymer and a flame retardant.

Also, the silicone polymer may have a composition ratio in the top insulator of 10 wt % to 20 wt %, and wherein the flame retardant may have a composition ratio in the top insulator of 10 wt % to 15 wt %.

Also, the silicone rubber may further include a pigment.

Also, the pigment may have a composition ratio in the top insulator of 5 wt % or less.

To solve the above problem, a secondary battery according to an embodiment of the present invention includes: a cylindrical battery can; an electrode assembly in the battery can; a cap assembly coupled to an upper portion of the battery can; a beading part provided on a front end of the battery can to mount the cap assembly; a crimping part configured to seal the battery can; and an insulator configured to insulate the electrode assembly, wherein the insulator includes: a glass fiber including crossed weft yarns and warp yarns of glass fiber raw yarns; and silicone rubber on at least one surface of the glass fiber.

Also, the insulator may include a top insulator between the electrode assembly and the cap assembly.

Also, the insulator may include a bottom insulator disposed between the electrode assembly and a bottom part of the battery can.

Also, the silicone rubber may include a first silicone rubber attached to the glass fiber raw yarns; and a second silicone rubber in a pore between the glass fiber raw yarns.

Also, the glass fiber raw yarns may cross each other in a shape in which the glass fiber raw yarns are perpendicular to each other, and wherein the second silicone rubber may be in the pore between the glass fiber raw yarns that are perpendicular to each other.

Also, the silicone rubber may include a first silicone rubber applied to at least one surface of the glass fiber, and a second silicone rubber applied to the first silicone rubber, wherein the first silicone rubber may be stacked on at least one surface of the glass fiber, and wherein the second silicone rubber may be stacked on the first silicone rubber.

Particularities of other embodiments are included in the detailed description and drawings.

Advantageous Effects

The embodiments of the present invention may have at least the following effects.

The silicone rubber may be applied to the glass fiber fabric to manufacture the top insulator for the secondary battery, thereby improving the properties such as the heat resistance and the chemical resistance.

In addition, when the top insulator fabric is punched to manufacture the top insulator for the secondary battery, the generation of the dust may be suppressed to enable the products to be continuously produced, increase in production amount, and decrease in manufacturing cost.

Also, the top insulator fabric may have the flexibility and be easily rolled to easily form the mother roll, and thus, the top insulator for the secondary battery may be easily manufactured.

The effects of the prevent invention are not limited by the aforementioned description, and thus, more varied effects are involved in this specification.

