KR20110015997A - Separator for non-aqueous electrolyte secondary battery, method for preparing thereof and non-aqueous electrolyte secondary battery using the same - Google Patents

Abstract

PURPOSE: A separator for non-aqueous electrolyte secondary battery is provided to prevent short circuit by suppressing sudden contraction and damage and to ensure safety, output characteristic, cycleability, and life span. CONSTITUTION: A separator for non-aqueous electrolyte secondary battery is surface-coated by a heat-resistant layer. The wettability of the surface of a separator substrate is 40 mN/m or more. A method for manufacturing the separator comprises the steps of: modifying the surface of the separator substrate with hydrophilic groups so that the wettability of the separator substrate is 40 mN/m or more; and applying a coating solution for the heat-resistant layer on the surface of the separator substrate.

Description

A separator for a non-aqueous secondary battery, a method of manufacturing the same, and a non-aqueous secondary battery comprising the same.

The present disclosure relates to a separator for a non-aqueous secondary battery, a manufacturing method thereof, and a non-aqueous secondary battery including the same.

In general, a non-aqueous secondary battery has a separator composed of an electrically insulating porous membrane interposed between a positive electrode and a negative electrode, and an electrolyte solution in which lithium salt is dissolved is impregnated in the pores of the porous membrane.

Such non-aqueous secondary batteries have high capacity and high energy density. However, when the positive electrode and the negative electrode are repeatedly contracted and expanded by the charge / discharge cycle, the separator or electrolyte reacts with the positive electrode and the negative electrode easily, deteriorates easily, a short circuit occurs inside and outside the battery, and the battery temperature rapidly increases. Will occur.

In order to solve this problem, a polyethylene porous membrane having excellent shutdown characteristics, ease of handling and cost has been widely used as a separator. In this case, the shutdown characteristic means that when the battery temperature rises due to overcharging or an external or internal short circuit, a part of the separator is melted to close the pores while closing the current.

In addition, when the battery temperature rises, the separator may melt and shrink or break rapidly, and a short may occur.

Therefore, in order to suppress reaction of an electrode, a separator, or electrolyte solution, and to prevent the breakage of a separator accompanying a rapid temperature rise, the research which adds a heat resistant layer to a separator has been advanced. In particular, Japanese Patent Application Laid-Open No. 2000-30686 discloses a secondary battery having a separator containing a heat-resistant layer containing a nitrogen-containing aromatic polymer and ceramic powder, and Japanese Patent Laid-Open No. 2000-327680 discloses a heat-resistant material made of porous material. The secondary battery provided with the separator containing a layer is disclosed.

However, in the secondary battery according to the above-mentioned patent document, problems such as leakage of the separator, degradation of the battery, increase in battery internal resistance, electrode degradation, leakage current due to decomposition of the electrolyte, and short circuit cannot be improved. In other words, in the secondary batteries described in Japanese Patent Laid-Open Nos. 2000-30686 and 2000-327680, it is not only difficult to uniformly provide a heat resistant layer on the surface of the substrate, but also has low adhesion and binding properties between the heat resistant layer and the substrate. Since physical interface resistance exists between these, battery characteristics and safety are still low.

One embodiment of the present invention is to provide a separator for a non-aqueous secondary battery having improved adhesion between the substrate and the heat resistant layer of the separator, and excellent in heat resistance.

Another embodiment of the present invention is to provide a method for manufacturing the separator for a non-aqueous secondary battery.

Another embodiment of the present invention is to provide a non-aqueous secondary battery comprising the separator for the non-aqueous secondary battery.

According to one embodiment of the present invention, a separator is formed by coating a substrate surface of the separator with a heat resistant layer, and the substrate surface of the separator provides a separator for a non-aqueous secondary battery having a wettability of 40 mN / m or more.

Since the above-mentioned separator for non-aqueous secondary batteries (hereinafter, simply referred to as a separator) is provided with sufficient hydrophilicity to the substrate surface of the separator, it is possible to uniformly apply a high polarity heat-resistant coating liquid. Therefore, the heat resistant layer can be formed uniformly on the surface of the separator substrate.

In addition, since sufficient hydrophilicity is imparted to the substrate surface of the separator, adhesion and binding property between the separator substrate surface and the heat resistant layer are improved, and the heat resistant layer is not peeled off even after repeated charging and discharging, and excellent heat resistance can be stably maintained. .

It is preferable that melting | fusing point of the said heat resistant layer is higher than melting | fusing point of the said separator base material.

Examples of such heat resistant layers include inorganic compounds or aromatic polyamides selected from the group consisting of oxides, carbonate compounds, hydroxides and phosphoric acid compounds.

According to another embodiment of the present invention, as a method for manufacturing a separator for a non-aqueous secondary battery, wherein the separator surface is covered with a heat resistant layer, the substrate surface of the separator is modified with a hydrophilic group, and the wettability of the separator substrate surface is 40. Provided are a method for producing a separator for a non-aqueous secondary battery, including a step of applying mN / m or more and a step of applying a coating liquid for a heat-resistant layer to the substrate surface of the separator modified by a hydrophilic group.

Examples of the method of modifying the substrate surface of the separator with a hydrophilic group include corona discharge, plasma treatment, ion implantation, or ion beam mixing.

According to another embodiment of the present invention, there is provided a non-aqueous secondary battery having the separator according to the present invention.

By protecting the contact between the separator substrate and the electrode, the heat resistant layer can prevent the separator and the electrode from reacting and deteriorating even when charge and discharge are repeated or a high voltage is applied. Therefore, it is possible to provide a non-aqueous secondary battery that can prevent the separator from contracting and breaking rapidly, preventing short circuits, having a long life, and having excellent battery characteristics such as safety, output characteristics, and cycle characteristics.

Hereinafter, exemplary embodiments of the present invention will be described in detail so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

According to one embodiment of the present invention, a separator is formed by coating a substrate surface of the separator with a heat resistant layer, and the substrate surface of the separator provides a separator for a non-aqueous secondary battery having a wettability of 40 mN / m or more. The non-aqueous secondary battery may take the form of a coin, a button, a sheet, a cylinder, a flat, a square, or the like, and may be configured with a positive electrode, a negative electrode, an electrolyte, a separator, and the like.

Examples of the anode include organic compounds such as complex oxides of transition metals such as Ti, Mo, W, Nb, V, Mn, Fe, Cr, Ni, and Co containing lithium, complex sulfides, vanadium oxides, and conjugated polymers. A conductive material, a Chevrel phase compound, or the like can be used as the active material.

For example, a carbon active material such as graphite or coke, metal lithium, lithium vanadium oxide, lithium transition metal nitride, silicon, or the like may be used as the negative electrode.

The positive electrode and the negative electrode may be optionally further formulated with additives such as an electrical conductive agent, a binder, a filler, a dispersant, an ionic electrical conductive agent, a pressure enhancer, and the like made of a powder made of an active material of electricity.

For example, graphite, carbon black, acetylene black, Ketjen Black, carbon fiber, metal powder, or the like can be used as the electrically conductive agent. As the binder, for example, polytetrafluoro ethylene, polyvinylidene fluoride, polyethylene and the like can be used.

For example, a method of manufacturing the positive electrode or the negative electrode may be obtained by adding a mixture of an active material and various additives to a solvent such as water or an organic solvent to form a slurry or paste, and the obtained slurry or paste may be prepared using a doctor blade method or the like. It can apply | coat to an electrode support board | substrate, dry, and crimp / compress with a rolling roll etc. to manufacture a positive electrode or a negative electrode.

The electrode support substrate may be formed of, for example, a foil made of copper, nickel, stainless steel, or the like, a sheet or net, or a sheet or net made of carbon fiber. On the other hand, the cathode can be manufactured by pressing and compressing in a pellet form without using an electrode supporting substrate.

For example, a nonaqueous electrolyte, a polymer electrolyte, an inorganic solid electrolyte, a composite material with a polymer electrolyte, an inorganic solid electrolyte, and the like in which the lithium salt is dissolved in an organic solvent can be used.

Examples of the solvent of the nonaqueous electrolyte include chain esters such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and methylethyl carbonate; γ-lactones such as γ-butyrolactone; Chain ethers such as 1,2-dimethoxy ethane, 1,2-diethoxy ethane and ethoxymethoxy ethane; Cyclic ethers of tetrahydrofuran; Nitriles, such as acetonitrile, can be used.

Examples of the lithium salt as a solute of the non-aqueous electrolyte include LiAsF ₆ , LiBF ₄ , LiPF ₆ , LiAlCl ₄ , LiClO ₄ , LiCF ₃ SO ₃ , LiSbF ₆ , LiSCN, LiCl, LiC ₆ H ₅ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiC ₄ P ₉ SO ₃ , and the like can be used.

The separator according to an embodiment of the present invention includes a separator substrate and a heat resistant layer coated on the separator substrate surface.

In addition, although the said heat resistant layer may be formed in the surface of at least any one pole of a separator base material, it may be formed in the both surfaces of a cathode side and an anode side.

As the separator substrate, a porous membrane made of polyolefin such as polypropylene or polyethylene, an olefinic nonwoven fabric, an aramid nonwoven fabric, an olefinic film, an aramid film or the like can be used.

On the other hand, the porous membrane made of polyolefin such as polypropylene or polyethylene is more preferable in terms of shutdown characteristics, ease of handling, and cost.

It is preferable that the porosity of the said separator base material is 40-90 volume%, More preferably, it is 50-80 volume%. When the porosity is less than 40% by volume, the ion conductivity of the separator may be lowered and the high rate discharge characteristics of the non-aqueous secondary battery may be lowered. On the other hand, if the porosity exceeds 90% by volume, it is preferable to use a separator substrate having a porosity in the above range because the separator lacks mechanical strength.

In addition, the separator base material preferably has a thickness of 60 μm or less, more preferably 10 to 30 μm. When the thickness exceeds 60 μm, the volume of the electrode plate increases, so that the energy density of the non-aqueous secondary battery may decrease, so that a separator having a thickness in the above range is preferably used.

As for the said separator base material, the surface is modified by hydrophilic groups, such as a COOH group and an OH group, and the wettability uses 40 mN / m or more. If wettability is less than 40 mN / m, it is difficult to apply | coat a highly polarizing heat-resistant coating liquid to the separator base surface uniformly, and a uniform heat resistant layer cannot be formed on the whole separator base surface. In addition, since the adhesion between the surface of the separator base material and the heat-resistant layer is also insufficient, there may be a problem that the heat-resistant layer peels off during repeated charge and discharge. Therefore, the heat resistance of the separator becomes insufficient, the resistance increase when the high current is lost, the IR drop may increase, and the output characteristics may be lowered. Therefore, it is preferable to use a separator substrate having the wettability in the above range.

It is preferable that melting | fusing point is higher than the said separator base material, and, for example, it is preferable that the heat resistant layer contains an inorganic compound and an aromatic polyamide.

Examples of the inorganic compound include LiAlO ₂ , LiAl ₅ O ₈ , Li ₅ AlO ₄ , MgO, MgAl ₂ O ₄ , BaTiO ₃ , CoAl ₂ O ₄ , Li ₂ SiO ₄ , Li ₂ B ₄ 0 ₇ , Li ₂ Oxides such as MoO ₃ , Li ₃ PO ₄ , AlPO ₄ , Li ₃ PO ₄ , YPO ₄ , phosphoric acid compounds such as (ZrO) ₂ P ₂ O ₇ , ZrP ₂ O ₇ , Al (OH) ₃ , Al (OH) carbonate compounds such as n · H ₂ O, Mg hydroxides, such as _{(OH) 2, MgCO 3,} BaCO 3, Li 2 CO 3 may be used. In this case, the inorganic compound may be used alone, or two or more kinds may be used in combination.

Examples of the aromatic polyamide include poly (phenylene terephthalamide), poly (benzamide), poly (4,4'-benzanilide terephthalamide), and poly (phenylene-4,4'-biphenylenedica Carboxylic acid amide), poly (phenylene-2,6-naphthalenedicarboxylic acid amide), poly (2-chloro-phenylene terephthalamide), phenylene terephthalamide / 2,6-dichlorophenylene terephthalamide and their Copolymers can be used. The optical properties of these aromatic polyamides may be meta or para.

These aromatic polyamides have a melting point of at least 180 ° C. Therefore, when the battery temperature rises, even if the separator substrate made of polyethylene having a melting point in the range of 120 to 130 ° C. or polypropylene having a melting point in the range of 140 to 150 ° C. is melted, the heat resistant layer is not melted, so that the skeleton of the separator can be maintained. It is. Therefore, a short can be prevented. In particular, the aromatic polyamide is more preferably an aromatic polyamide having a melting point of 250 ° C or higher.

The heat resistant layer containing such an inorganic compound or aromatic polyamide is porous containing a large number of pores. The porosity of the heat resistant layer is preferably 50 to 90% by volume, more preferably 60 to 90% by volume. If the porosity is less than 50% by volume, the cushioning property of the heat resistant layer is lowered, and the volume change due to expansion and contraction during electrode charge / discharge cannot be sufficiently absorbed. On the other hand, if the porosity is greater than 90% by volume, the mechanical strength is insufficient and can be easily broken, it is preferable to use a heat resistant layer having a porosity in the above range.

It is preferable that the thickness (one thickness) of the said heat resistant layer is 2 micrometers or more, More preferably, it is 2-20 micrometers, More preferably, it is 2-10 micrometers. When the thickness of the heat resistant layer is less than 2 µm, the volume change due to expansion and contraction of the electrode accompanying charge and discharge cannot be sufficiently absorbed, and the reinforcing effect on the separator substrate is also insufficient. In addition, when the battery temperature rises and the separator substrate is melted, shortage may occur because the skeleton of the separator cannot be maintained. On the other hand, when the thickness of the heat resistant layer is excessive, since the resistance may increase and the characteristics of the battery may be deteriorated, it is preferable to use a heat resistant layer having the thickness in the above range. However, when the safety of the secondary battery is considered as a top priority, the thickness of the heat resistant layer is preferably thick.

When the heat-resistant layer simultaneously contains an aromatic polyamide and an inorganic compound, when the content ratio thereof is 5 to 50% by weight of an aromatic polyamide, it is preferable that the inorganic compound is 95 to 50% by weight, more preferably aromatic polyamide. When the amide is 10 to 30% by weight, the inorganic compound is 90 to 70% by weight, and more preferably when the aromatic polyamide is 15 to 25% by weight, the inorganic compound is 85 to 75% by weight.

When the inorganic compound is less than 50% by weight relative to the aromatic polyamide, the effect of enhancing heat resistance to the porous formed by the aromatic polyamide and stabilizing effect of the transition metal included in the electrode may be insufficient. On the other hand, when the inorganic compound exceeds 95% by weight with respect to the aromatic polyamide, the formation of the porous by the aromatic polyamide is inhibited by the inorganic compound, so that the strength may decrease and recede. In addition, when the content of the inorganic compound is included in the content outside the range of 95 to 50% by weight, the battery resistance of the secondary battery is easily increased and deteriorated.

According to another embodiment of the present invention, a method of manufacturing a separator for a non-aqueous secondary battery according to the present invention using the following method is provided.

First, the base material surface of the separator which consists of polyethylene, a polypropylene, etc. is modified by a hydrophilic group, and the wettability of the surface material of a separator is made 40 mN / m or more.

The method of modifying the surface of the separator substrate with a hydrophilic group is a method generally used in the art, and is not particularly limited. For example, a method using corona discharge, plasma treatment, ion implantation, ion beam mixing, or the like may be used. It can be used selectively according to the kind of separator base material.

By modifying the surface of the separator substrate with a hydrophilic group using the above method, it is easy to apply the coating liquid for a high polarity heat-resistant layer to a separator substrate having a low polarity such as polypropylene. That is, a heat resistant layer can be formed uniformly on the whole surface of a separator base material.

Subsequently, the coating liquid for a heat resistant layer is apply | coated to the base material surface of the said separator modified by the hydrophilic group, and a heat resistant layer is formed.

More specifically, the aromatic polyamide is dissolved in polar organic solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone and tetramethyl urea. A slurry solution is prepared by dispersing an inorganic compound in the aromatic polyamide solution. The obtained slurry solution is applied to the surface of the separator base material using the coating liquid for the heat resistant layer.

The separator obtained by applying the slurry solution is mounted at a temperature of 20 ° C. or higher and constant humidity so that the aromatic aramid in which the inorganic compound is dispersed on the surface of the separator substrate is precipitated. Thereafter, the separator is immersed in a coagulating solution composed of an aqueous solution, an alcoholic solution, or the like. Thereafter, the polar organic solvent is removed by evaporation from the separator surface. When the separator from which the polar organic solvent has been removed is dried below the melting point of the separator substrate, a separator having a heat resistant layer formed on the surface of the substrate is obtained.

According to another embodiment of the present invention, there is provided a non-aqueous battery comprising the separator for the non-aqueous secondary battery.

Hereinafter, examples and comparative examples of the present invention are described. However, the following examples are only examples of the present invention and the present invention is not limited to the following examples.

[ Example  One]

The binder material of polyvinylidene fluoride (kureha Chemical Co., Ltd., # 1100) is dissolved N- methyl-2-pyrrolidone to prepare a solution, and money, LiNi Co _{0 .80 0 .15 0 .05} Al in the resulting solution 85% by weight of O ₂ (hereinafter, NCA) and 10% by weight of conductive carbon were mixed and slurried. The prepared positive electrode slurry was uniformly applied onto an Al thin film having a thickness of 15 μm, and dried to prepare a positive electrode. The positive electrode had a weight ratio of NCA: electroconductive carbon: polyvinylidene fluoride 85: 10: 5.

By rolling, the positive electrode mixture was adjusted to have a density of 2.4 g / cm ³ . The final thickness was 60 μm. The electrode plate was cut to have a length of 210 mm and a width of 54 mm, and the 10 mm portion in the longitudinal direction was stripped of the positive electrode mixture material, and an aluminum lead was welded thereto. In addition, a positive electrode plate was prepared by vacuum drying at 100 ° C. for 10 hours.

Thereafter, using the carbon material powder as a negative electrode active material, 96% by weight of the carbon material powder and 4% by weight of polyvinylidene fluoride to be a binder were mixed and dispersed in N-methyl-2-pyrrolidone to prepare a negative electrode slurry. It was. The negative electrode slurry was uniformly coated on a copper thin film having a thickness of 10 μm, and dried to prepare a negative electrode.

By rolling, it adjusted so that the density of negative electrode mixture might be 1.2 g / cm <^3> . The final thickness was 70 μm. It cut so that a pole plate size might be 250 mm in length, and 58 mm in width, The 10 mm part of the longitudinal direction peeled the negative electrode compound material, and welded the nickel lead to it. Further, a negative electrode plate was prepared by vacuum drying at 100 ° C. for 10 hours.

A separator substrate made of a porous film of polypropylene (PP) was subjected to corona discharge using ASA-4 (manufactured by Shin-Kwang Electric Instrument Co., Ltd.) at the voltages and treatment rates shown in Table 1 below, and the separator substrate surface was modified with a hydrophilic group. It was. The wettability of the surface of the separator base material after corona discharge was evaluated as follows. The results are shown in Table 1 below.

<Wetability Evaluation>

The wettability was evaluated according to Japanese Industrial Standard (JIS K 6768), and 22.6 to 73 mN / m of commercially available standard solution (JIS K 6768) was immersed in a cotton swab and then applied to the surface of the separator substrate after corona discharge. At this time, the minimum value of the test mixed solution number (mN / m) wet to the surface without water repellency was recorded and evaluated by the index. The wettability of Example 1 was 47 mN / m.

To the separator substrate after corona discharge, a coating liquid for a heat-resistant layer containing aromatic polyamide (poly (phenylene terephthalamide)) and Al (OH) ₃ in a weight ratio of 15:85 was 4 μm on one side of the separator substrate. The separator was applied to produce a separator having a heat resistant layer.

In addition, in order to evaluate the adhesion and binding property of the heat resistant layer, the following test was performed on the separator on which the heat resistant layer was formed. The results are shown in Table 1 below.

<After peeling test Heat-resistant  Survival Assessment>

Evaluation of the heat resistant layer was evaluated by attaching a vinyl tape (JIS C 2336) to a separator with a grid of 1 cm intervals, checking the state of the grid after peeling off, and measuring the residual ratio of the heat resistant layer. . The residual ratio of Example 1 was 80%.

The positive electrode plate, the negative electrode plate, and the separator prepared as described above were placed in the order of the negative electrode plate, the separator, and the positive electrode plate, and the aluminum lead of the positive electrode was placed on the inner circumferential side, and the nickel lead of the negative electrode was placed on the outermost circumferential side, and then laminated. The laminated negative electrode plate, separator, and positive electrode plate were wound to form an electrode group. At this time, the negative electrode plate, which is the outermost circumference, was tensioned until the coated portion of the negative electrode mixture was completely wound and the negative electrode lead was wound around the separator, and then cut out together with the separator. Then, after winding so that the outer peripheral part may not loosen, the outermost negative electrode lead was fixed with tape, and the electrode element was produced.

The electrode element was inserted into a battery can and impregnated with a mixture of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate in a volume ratio of 30:40:30 as a nonaqueous electrolyte so that LiPF ₆ was dissolved to 1 mol / L. . A 18650 size cylindrical battery was obtained with a battery cover serving as a positive electrode terminal and a gasket.

In order to evaluate the battery characteristics of the obtained secondary battery, the following test was performed. The results are shown in Table 1 below.

<Capacity maintenance characteristic evaluation>

After charging the secondary battery at a constant current (0.5C) and a constant voltage (4.3V), 300 cycles of 0.5 C discharge were carried out to a discharge starting voltage of 2.75 V, and the capacity retention rate after the end of 300 cycles was measured. The capacity retention rate of Example 1 was 92%.

<Output characteristic evaluation>

The secondary battery was adjusted to 60% SOC (charged state), discharged at 3 C for 10 seconds, and discharge was stopped for 10 seconds. Subsequently, charging was carried out at 3 C for 10 seconds and charging was stopped for 10 seconds.

In the same manner, measurements were made continuously under the conditions of 5 C and 10 C. The OCV (opening potential) and the voltage after 10 seconds of discharge of 3 C, 5 C, and 10 C before the test were plotted on the Y axis and the current value was plotted on the X axis. Plot. The plotted straight line was extended, the current value at 2 V was obtained, and the output characteristic was obtained by substituting the equation for output (W) = current value (A) x 2 (V). The output characteristic of Example 1 was 11W.

[ Example  2, 3 and 4]

A battery was produced and evaluated in the same manner as in Example 1 except that the speed of the corona discharge treatment was changed as shown in Table 1 below.

[ Example  5]

A battery was produced and evaluated in the same manner as in Example 1 except that polyethylene (PE) was used as the separator substrate and the conditions of the corona discharge treatment were changed as shown in Table 1 below.

[ Comparative example  One]

A battery was produced and evaluated in the same manner as in Example 1 except that the heat resistant layer was not applied without performing a corona discharge.

[ Comparative example  2 and 3]

A battery was produced and evaluated in the same manner as in Example 1 except that the conditions of the corona discharge treatment were changed as shown in Table 1 below.

[ Comparative example  4]

A battery was produced and evaluated in the same manner as in Example 1 except that polyethylene (PE) was used as the separator substrate and the conditions of the corona discharge treatment were changed as shown in Table 1 below.

[ Comparative example  5]

A battery was produced and evaluated in the same manner as in Example 1 except that polyethylene (PE) was used as the separator substrate and the heat resistant layer was applied without performing corona discharge.

TABLE 1

Separator base material Corona Discharge Treatment Wettability
(mN / m) Residual state of heat-resistant layer after peel test (%) Capacity Maintenance Characteristics
(%) Print
characteristic
(w) Voltage
(V) speed
(m / min) Example One PP 14 3 47 80 92 11 2 PP 14 12 44 80 91 11 3 PP 14 18 42 70 88 10 4 PP 10 3 41 70 88 10 5 PE 14 12 42 90 93 11 Comparative example One PP - - 30 Coating liquid not applicable 30 7 2 PP 10 20 34 20 34 7 3 PP 5 3 34 20 37 7 4 PE 5 20 33 50 73 8 5 PE - - 31 40 70 7

As shown in Table 1, in Examples 1 to 5 using the separator substrate whose surface wettability was improved to 40 mN / m or more by corona discharge treatment, the evaluation results of the adhesion and binding properties of the heat-resistant layer were found on the substrate surface. It was confirmed that most of the formed heat-resistant layer remained without peeling, and the battery using such a separator was confirmed to have excellent cycle characteristics and output characteristics.

On the other hand, in Comparative Examples 1 to 5 in which the wettability of the separator base surface was less than 40 mN / m, it was difficult to apply the coating liquid for the heat-resistant layer uniformly to the separator base surface, and as a result of evaluation of the adhesion and binding properties of the heat-resistant layer, It was confirmed that most of the heat-resistant layer peeled off. In addition, it was confirmed that the battery using such a separator had poor cycle characteristics and output characteristics.

According to one embodiment of the present invention from the above results, the adhesion between the separator base material and the heat-resistant layer is improved, so even after repeated charge and discharge, the heat-resistant layer is maintained on the surface of the separator base material, the reaction between the separator and the battery and Deterioration by the above reaction was suppressed, and it was clearly confirmed that a non-aqueous secondary battery having excellent battery characteristics was obtained.

The present invention is not limited to the above embodiments, but may be manufactured in various forms, and a person skilled in the art to which the present invention pertains has another specific form without changing the technical spirit or essential features of the present invention. It will be appreciated that the present invention may be practiced as. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (7)

A separator in which the substrate surface of the separator is covered with a heat resistant layer, wherein the substrate surface of the separator has a wettability of 40 mN / m or more. The method of claim 1, The melting point of the heat-resistant layer is higher than the melting point of the separator substrate separator for non-aqueous secondary battery. The method of claim 1, The heat-resistant layer is a separator for a non-aqueous secondary battery containing an inorganic compound selected from the group consisting of oxides, carbonate compounds, hydroxides and phosphate compounds. The method of claim 1, The heat resistant layer is a separator for a non-aqueous secondary battery containing an aromatic polyamide. As a manufacturing method of the separator for non-aqueous secondary batteries, in which the base material surface of a separator is coat | covered with the heat resistant layer, Modifying the substrate surface of the separator with a hydrophilic group to make the wettability of the separator substrate surface 40 mN / m or more; and A method for producing a separator for a non-aqueous secondary battery, comprising the step of applying a coating liquid for a heat-resistant layer to the substrate surface of the separator modified by a hydrophilic group. The method of claim 5, The method of modifying the substrate surface of the separator with a hydrophilic group is a method of manufacturing a separator for a non-aqueous secondary battery using a method selected from the group consisting of corona discharge, plasma treatment, ion implantation, and ion beam mixing. A non-aqueous secondary battery comprising the separator for non-aqueous secondary batteries according to any one of claims 1 to 4.