KR20000065612A - Texture-type separator for the electrochemical cell - Google Patents

Abstract

PURPOSE: A separating layer for an electric-chemical energy device is provided to simplify a manufacturing process of an electric-chemical energy device such as a battery and a capacitor. CONSTITUTION: A separating layer for an electric-chemical energy device comprises a separating layer formed with a natural polypeptide fiber. A diameter of the natural polypeptide fiber of the separating barrier is 1 to 20micrometer. A size of an aperture within a lattice of the separating layer is 1 to 1000micrometer. A thickness of the lattice is 1 to 150micrometer. In the separating layer for an electric-chemical energy device, the electric-chemical energy device is an aqueous battery, a non-aqueous battery, an aqueous capacitor, or a non-aqueous capacitor.

Description

Separators for electrochemical energy devices {Texture-type separator for the electrochemical cell}

The present invention relates to a separator for an electrochemical energy device, and more particularly, to a separator woven from natural polypeptide-based fibers in an electrochemical energy device consisting of an electrode, an electrolyte and a separator.

Recently, due to the development of the information and communication industry, energy devices using electrochemical principles such as batteries and capacitors, which are compact, lightweight, thin and portable, and have high energy density, are required. And a cathode), an electrolyte and a separator.

Korean Patent Application No. 83-3192 discloses an electrode assembly used in an electrochemical cell in which a separator separates a cell into a positive electrode and a negative electrode, and the porous porous mesh primary electrode occupies at least one part and also makes perfect physical contact with the separator. A distributor is described, in which a current supplier is internally connected to an electrode, so that current is distributed to the electrode without electrical resistance between the electrode and the current supplier, and the electrolyte can be circulated into or onto the electrode site. 95-6584 discloses a sealed alkali-zinc secondary battery having an electrolyte-moisture separator and a microporous film separator for preventing battery short-circuit between an alkaline positive electrode and a zinc negative electrode having a thickness of 50-150 m in contact with the zinc negative electrode. It is described.

In addition, Korean Patent No. 74824 describes a method for producing an open-cell microporous membrane, which is used as a filter medium, a solute extraction membrane, a blood oxygenation membrane, and a battery separation membrane, and has an increased pore density and a reduced pore size.

As such, the separators essential for electrochemical energy devices, such as batteries and capacitors, are used to prevent short circuits between electrodes, are insulating, ion-exchangeable, and have excellent moldability to be manufactured in various forms. Required. Until now, polyolefin-based porous separators such as polyethylene and polypropylene, separators woven from pulp, paper, and glass fiber have been used, and the separators are selected according to the type of electrolyte, and various shapes such as rectangular or cylindrical. Used as

However, polyolefin-based membranes are expensive and can be used in liquid electrolytes but cannot be used in polymer electrolytes. Membranes woven from glass fibers can be used in aqueous solutions such as acids, but in polymer-gel electrolytes. It is difficult to use.

In addition, paper or pulp is commonly used in water-soluble alkali electrolytes, and there is a problem that expensive high-quality paper should be used due to powder such as SiO ₂ chemically treated in paper or pulp. Depends.

In order to overcome this problem, the present inventors have conducted extensive research and found that the membrane can be manufactured using natural polypeptide-based fibers, and the present invention has been completed based on this.

Accordingly, an object of the present invention is to provide a membrane for an electrochemical energy device that can greatly improve the ion conductivity of the electrolyte and the interfacial characteristics between electrodes, and has excellent chemical resistance, electrochemical and thermal stability, and excellent moldability. .

The separator of the present invention for achieving the above object is a separator for an electrochemical energy device, the separator is made of a woven fabric made of natural polypeptide-based fibers.

1 is an optical micrograph of a membrane woven from natural polypeptide-based fibers according to the present invention,

2 is a voltage-current curve obtained by applying the separator according to the present invention on a polyacrylonitrile-based polymer gel.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

As noted above, a feature of the present invention is the use of woven fabrics of natural polypeptide based fibers as separators for electrochemical energy devices.

The natural polypeptide fiber according to the present invention is generally referred to as silk, that is, silk fiber, and is a fiber obtained by being generally secreted from silkworms. It is relatively inexpensive and has good mechanical strength. In addition, natural polypeptide fibers do not swell in organic solvents and are also excellent in chemical resistance.

As described above, since the natural polypeptide can be obtained thinly in the form of fibers, it can be easily manufactured in a woven fabric, and the size of the lattice, the thickness of the membrane, and the like can be easily produced in the desired form. It is excellent, so that the thickness of the woven fabric can be made thinner, thereby reducing the resistance.

In addition, since the natural polypeptide-based fiber separator does not swell or dissolve in organic electrolyte solvents such as ethylene carbonate, propylene carbonate, diethyl carbonate, and dimethyl carbite, and has excellent chemical resistance and chemical resistance, the membrane has excellent contact resistance between electrodes. It can improve the interfacial properties and improve the ion conductivity between electrodes, and is electrochemically stable in the range of 0 to 5 volts for lithium electrodes, and shows thermal stability up to 200 ° C, requiring excellent insulation, chemical resistance and thermal stability. It is suitable as.

In particular, when a gel electrolyte is used, a membrane-type separator must be used. When a natural polypeptide-based woven material is used as a separator for gel electrolyte, it also serves as a reinforcing agent of the gel, so that a separate gel electrolyte film needs to be prepared. Absence, can simplify the manufacturing process of the electrochemical energy device. That is, it is possible to manufacture a variety of forms of energy devices, such as batteries and capacitors using a solid or gel electrolyte, and has many advantages in terms of securing safety of energy devices by fundamentally blocking a short circuit.

The natural polypeptide-based fiber separation membrane is prepared using a single natural polypeptide or a plurality of constituent fibers having a diameter of 1 to 20㎛, preferably about 10㎛, if the diameter of the fiber is less than 1㎛ There is a possibility that the electrode may be short-circuited, and when the thickness exceeds 20 µm, the thickness of the woven material becomes large, which causes a problem of increasing the resistance.

In addition, the size of the pores (see Fig. 1) in the natural polypeptide-based fiber membrane lattice is preferably such that the horizontal and vertical lengths each have a range of 1 to 1000㎛. If the length of the lattice is less than 1 mu m, the lattice spacing is too dense to reduce the ion conductivity of the electrolyte. If the length of the lattice exceeds 1000 mu m, the lattice is too large and the electrode may be shorted.

In addition, the thickness of the separator is preferably 1 to 150 μm. If the thickness is less than 1 μm, the electrode may be short-circuited. If the thickness of the separator exceeds 150 μm, the resistance of the electrolyte is increased.

1 is an optical micrograph of a membrane woven from natural polypeptide fibers according to the present invention. The performance of a separator for an electrochemical energy device is determined by the thickness of the woven fabric constituting the separator and the size of the pores in the lattice. The natural polypeptide fibers of the woven fabric consist of a single yarn or a plurality of yarns, and the size of the pores in the woven lattice depends greatly on the properties of the electrolyte. In more detail, in the liquid electrolyte, the pore size in the lattice may be 1 μm or less in the lattice, but the lattice size is preferably 1 to 1000 μm in the solid or organic and inorganic gel electrolyte.

In addition, Figure 2 is a voltage-current curve obtained by applying the separator according to the present invention on a polyacrylonitrile-based polymer gel, the dotted line is when the separator of the present invention was used, the solid line is not used It is shown. It can be seen that the electrochemically stable at 0 ~ 4.6V with respect to lithium which is a separator made of natural polypeptide-based fibers.

In addition, the separator according to the present invention can be used in devices of aqueous batteries, non-aqueous batteries, aqueous capacitors or non-aqueous capacitors, for example, Zn-Mn-based primary and secondary batteries A battery and an alkaline battery are mentioned, A lithium battery, a lithium polymer battery, a lithium ion polymer battery, etc. are mentioned as a non-aqueous battery.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to the following Examples. On the other hand, unit "%" means "% by weight" unless otherwise specified.

Example 1

Polyacrylonitrile, propylene carbonate, ethylene carbonate, lithium perchlorate, and fumed SiO ₂ were prepared in the polymer gel electrolyte consisting of 14, 40, 40, 5, and 1 in the weight ratio of the woven fabric as a separator. A woven fabric made of a natural polypeptide fiber having a diameter of 10 μm of 90 μm was used, and the ion conductivity according to the size and thickness of the separator was measured in an impedance frequency responder, and is shown in Table 2 below. As can be seen, the separator of the present invention has a preferable ion conductivity of 10 ⁻³ or more, and the separator is stable in the range of 0 to 4.6 V electrochemically with respect to lithium as shown in FIG. 2.

Example 2

2% fumigated SiO ₂ was added to an aqueous solution exhibiting 2.3 x 10 ^-2 S / cm by sodium chloride, and a membrane was prepared as a natural polypeptide fiber having a diameter of 10 µm with a thickness of 90 µm as a separator in an aqueous electrolyte based on a gel. A woven fabric was used, and the influence of the lattice size of the separator on the ion conductivity was measured in the same manner as in Example 1, and is shown in Table 1 below.

Horizontal and vertical lengths of pores in the lattice (μm × μm) Ion Conductivity (S / cm) 10 × 30 2.2 × 10 ^-2 20 × 30 2.3 × 10 ^-2 30 × 30 2.3 × 10 ^-2 40 × 30 2.3 × 10 ^-2 50 × 30 2.3 × 10 ^-2 60 × 30 2.3 × 10 ^-2

Example 3

A lithium ion polymer battery was prepared by using a separator made of natural polypeptide fibers in a polymer gel-like electrolyte prepared in Example 1, thereby producing 1 mA / As a result of measuring the charge / discharge capacity and utilization rate while passing a constant current, the charge / discharge capacity was over 100mA / h, and the utilization rate was over 95% based on the electrode active material. The initial charge / discharge efficiency was over 99% and the life span was 500 times. The above was maintained.

Comparative Example 1

As a separator, the experiment was carried out in the same manner as in Example 1 except that cellgard (cellgard), which is a porous polypropylene separator used in a lithium ion liquid battery, was ionized according to the size and thickness of the separator. Conductivity was measured as in Example 1 and shown in Table 2 below.

Example 1 Comparative Example 1 Horizontal and vertical lengths of pores in the lattice (μm × μm) Ion Conductivity (S / cm) Ion Conductivity (S / cm) 10 × 30 2.0 × 10 ^-3 2.1 × 10 ^-5 20 × 30 2.2 × 10 ^-3 2.3 × 10 ^-5 30 × 30 2.4 × 10 ^-3 2.5 × 10 ^-5 40 × 30 2.4 × 10 ^-3 2.5 × 10 ^-5 50 × 30 2.5 × 10 ^-3 2.6 × 10 ^-5 60 × 30 2.5 × 10 ^-3 2.6 × 10 ^-5

As described above, the method of the present invention can simplify the manufacturing process of electrochemical energy devices such as batteries, capacitors, etc., and greatly improves safety by preventing short circuits between electrodes. In particular, a woven fabric of natural polypeptide fibers can be used as a separator in an electrolyte on a polymer gel to freely modify the shape of the energy device.

Claims (3)

Separation membrane for an electrochemical energy device, the separation membrane for an electrochemical energy device, characterized in that the woven fabric consisting of natural polypeptide-based fibers. According to claim 1, wherein the diameter of the natural polypeptide fibers of the membrane is 1 to 20㎛, the pore size in the membrane lattice is 1 to 1000㎛ horizontal and vertical length, respectively, the lattice thickness is 1 ~ 150㎛ Separator characterized in that. The separator according to claim 1, wherein the device is an aqueous battery, a nonaqueous battery, an aqueous capacitor or a nonaqueous capacitor.