JP6133520B2 - New modified non-woven lithium ion battery separator and method of manufacturing the same - Google Patents

Description

  The present invention relates to a new modified nonwoven fabric lithium ion battery separator, and further relates to a method of manufacturing the battery separator.

  Currently, commercially available polyethylene and polypropylene separators are applied to batteries for digital products such as mobile phones and cameras. However, such separators have some deficiencies. On the other hand, since the melting temperature of polyolefin is lower than 165 ° C., the separator may be destroyed when the external temperature of the battery is too high or subjected to an unexpected impact. In this case, the battery is short-circuited. Causes battery combustion and explosion. On the other hand, the performance of the polyolefin's parent electrolyte is poor and the performance of retaining the electrolyte is insufficient, which causes poor performance such as battery cycle life and large current charge / discharge. The lack of safety and electrical performance of such separators limits their use in power storage batteries.

  In order to improve the safety performance and liquid absorption performance of the separator, Chinese Patent Publication No. CN10262679A provides a three-layer nanofiber lithium ion composite separator, which has good thermal stability, pores The rate is high, the liquid absorption capacity is high, and the mechanical strength can be improved by the hot composite press. However, since the composite structure of three layers is formed by electrospinning spray and the peel strength of the separator is low, the interfacial resistance is large, the internal resistance of the manufactured battery is large, and it is not advantageous for large current charge / discharge of the power storage battery. In addition, the hole diameter is large, the high-voltage insulation is poor in the battery manufacturing process, and the short circuit rate in the battery reaches 10%.

  Chinese Patent Document No. CN1679185 provides a ceramic separator for use in high power lithium ion batteries. In the separator, a ceramic coating layer, oxide particles containing Al, Zr, and Si elements, and an inorganic material having an ion conductive function are applied to a nonwoven fabric substrate. The maximum advantage of the separator is that the ion conductivity is high, the melting point is higher than 250 ° C., the thermal stability is good, the electrochemical stability is good, and the performance of the manufactured battery on large current charge / discharge is excellent. However, the inorganic material of the separator coating layer is exposed to the outer surface and easily absorbs water, and the manufactured separator has extremely high water absorption. In the battery manufacturing process, it is difficult to remove moisture in a normal drying process, and when a relatively large amount of moisture in the separator enters the battery system and the moisture reacts with the electrolyte, the battery expands, the internal resistance increases, and the battery The electrochemical performance of the battery is poor. For example, the capacity loss of the battery is large and the cycle life is poor. In addition, that the adhesive force of the brittle inorganic coating layer with respect to a flexible base material worsens the machine operativity in a battery processing process. Problems such as bending voids, cracks, and damage are likely to occur in the separator, and a short circuit of the battery occurs. To solve battery expansion, longer drying times or higher temperatures are required in the battery fabrication process to remove moisture, increasing the possibility of damage and flaking of the brittle inorganic coating. Furthermore, since the strength of the separator is poor, the processing requirements for high-speed automatic winding cannot be satisfied, the ability to withstand penetration by electrode dust is weak, and the short-circuit rate is high.

  The inventor has performed different performance optimizations on the separator described above and found significant room for improvement from the above analysis. Since the power storage battery is required to be a high-capacity and high-power charge / discharge battery, there are high demands on the separator for safety performance and electrical performance. Therefore, the separator must have the performances such as good thermal stability and electrochemical stability, high lithium ion conductivity, excellent liquid absorption and retention performance, low water content and easy battery processing. Don't be.

  In order to solve the problems that conventional lithium ion battery separators are easy to absorb water, have poor heat resistance and not high strength, and improve the service life and safety of lithium ion batteries, the present invention A separator for a non-woven lithium ion battery is provided, and a method for producing the battery separator is further provided.

  In order to solve the above problem, the technical solution of the present invention is as follows.

  A separator for a new modified nonwoven fabric lithium ion battery, wherein the separator includes a modified nonwoven fabric substrate and a composite filler thereof.

  The filler is filled in the pores of the modified nonwoven fabric substrate. At this time, the filler is filled in the pores of the nonwoven fabric substrate. Preferably, the filler extends outward from the pores of the modified nonwoven fabric substrate and covers the entire modified nonwoven fabric substrate. The thickness of the separator is 1 to 10 times the thickness of the modified nonwoven fabric substrate. More preferably, the thickness of the separator is 1 to 2 times the thickness of the modified nonwoven fabric substrate. In this case, the structure of the modified nonwoven fabric lithium-ion battery separator is a single-layer nonwoven fabric fiber layer in which the filler is filled in the pores of the nonwoven fabric substrate, and the filler also covers the surface of the nonwoven fabric substrate.

  In the modified nonwoven fabric base material, uniformly arranged pores having a pore diameter of 1 to 50000 nm are distributed on the base material, so that the thickness of the modified composite film of the nonwoven fabric and the uniformity of the pore diameter structure are ensured. The porosity of the substrate is 30 to 95% based on factors such as the principle of liquid absorption by capillaries and the surface tension of the liquid. When the porosity exceeds 30%, the manufactured separator has better liquid absorption and retention performance, guarantees smooth conduction of lithium ions in the separator, the internal resistance of the manufactured battery is low, and the battery Easy to charge and discharge with high output. However, when the porosity is greater than 95%, the strength of the nonwoven fabric substrate is insufficient, the processability of the manufactured separator battery is poor, and the yield is low.

  The modified non-woven fabric substrate includes a low melting point material and a high melting point material. The low melting point material is melt crystallized. The high melting point material is 85-99.9% of the total weight of the modified nonwoven fabric substrate. The remainder is a low melting point material. The high melting point material is manufactured by mixing one or more kinds of polyester, polyolefin, nitrile polymer, aromatic polyimide, and polyether having a melting point ≧ 200 ° C. Polyesters include, but are not limited to, polyethylene terephthalate (PET), polytrimethylene terephthalate (PPT), polybutylene terephthalate (PBT), polyethylene phthalate materials. Polyolefin fibers include, but are not limited to, polymethylpentene materials. Cellulose-based materials include, but are not limited to, polyvinyl formal-nanocellulose and tencel materials. Polynitrile systems include but are not limited to polyacrylonitrile (PAN) materials. Polyether systems include, but are not limited to, aromatic polyether materials. Polyether systems include, but are not limited to, polyetheretherketone, polyethersulfone, polyphenylene oxide, and polyphenylene sulfide materials. The low melting point material is one or more of polyolefin, polyvinyl alcohol, polystyrene, heat-adhesive polyester, and fluorine-based polymer having a melting point of 50 to 199 ° C.

  A substrate composed of a low melting point material and a high melting point material is selected, and the substrate has a bimodal melting point. For a given amount of heat and mechanical pressure, a low-melting-point material with a low weight ratio begins to soften and melt, changing the original fiber type and re-forming a structure with a flat and uniform surface, while the weight ratio is Large refractory materials do not change due to their high temperature stability. After the amount of heat and pressure are released, the molten low melting point melt is cooled and solidified or recrystallized to firmly bond the high melting point material. The strength and surface flatness of the entire substrate are improved, and the substrate has a tensile strength of 60 MPa and a puncture strength of 3N. The low melting point material accounts for 0.1 to 15% of the substrate weight, and the high melting point material accounts for 85 to 99.9% of the substrate weight. When the content of the low-melting-point material exceeds 15%, the poorer the heat shrink performance of the manufactured base material, the more easily the separator shrinks at a high temperature. When the content of the low melting point material is lower than 0.1%, the rougher the surface roughness of the manufactured base material, the worse the uniformity of the thickness, the lower the mechanical strength, The passing rate is low.

  In the present invention, the melt crystallization treatment is preferably a process in which the low melting point material is heated and melted at a temperature 0 to 10 ° C. higher than the melting point of the low melting point material, and then cooled and crystallized. Since the melting temperature is 0 to 10 ° C. higher than the melting point of the low melting point material, the low melting point material having a small weight ratio softens and melts, changes the original fiber type, and has a structure having a flat and uniform surface. On the other hand, a high melting point material with a large weight ratio does not change due to its high temperature stability. When the heating is stopped and the temperature is lowered, the high-melting point substance is firmly bonded by the cooled crystal of the melted low-melting point melt, and the strength of the whole substrate is improved.

  The filler in the modified nonwoven fabric substrate comprises an organic polymer and a first filler material and / or a second filler material.

  The organic polymer is one type or a combination of two or more types such as a fluorine-based polymer, rubber, ester-based polymer, cellulose, and starch. The fluoropolymer includes, but is not limited to, polyvinylidene fluoride, polyvinylidene fluoride hexafluoropropylene, polytetrafluoroethylene, and polyvinylidene fluoride trichloroethylene. The rubber includes, but is not limited to, styrene butadiene rubber, carboxylated styrene butadiene rubber, nitrile butadiene rubber, and silicone rubber. Examples of the ester-based polymer include, but are not limited to, polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polyacrylic acid glyceride, methacrylic acid ethylene glycol ester, polyethylene vinyl acetate, and polyvinyl acetate. The cellulose includes, but is not limited to, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, carboxymethyl cellulose, and mixtures thereof. The starch includes, but is not limited to, cyanoethyl pullulan, pullulan and the like.

  The selected organic polymer has a parent electrolyte characteristic so as to ensure the liquid absorption performance of the separator, and guarantees the ionic conductivity of the separator and the cycle performance of the battery. The selected organic polymer has adequate creep performance and wettability with the filler material so as to bind and cover the filler material.

  The first filling material is an inorganic granule having a particle size of 1 to 2000 nm, preferably 10 to 1000 nm, and more preferably 50 to 500 nm. The first filling material is inorganic nanoparticles and mainly plays a role of filling the nonwoven fabric pores and improving the high-temperature stability of the separator. The first filling material includes, but is not limited to, one or more kinds of inorganic oxide nanoparticles, inorganic nitride nanoparticles, and ore nanoparticles. The inorganic oxide nanoparticles are at least one of silicon dioxide, aluminum oxide, titanium dioxide, zirconia, magnesium oxide, magnesium hydroxide, yttrium oxide, zinc oxide, iron oxide, and cerium dioxide. The inorganic nitride nanoparticles are at least one of silicon nitride, titanium nitride, and boron nitride. The ore nanoparticles are calcium carbonate, calcium sulfate, aluminum hydroxide, potassium titanate, barium titanate, talc, kaolin clay, kaolinite, pyrophyllite, montmorillonite, mica, bentonite clay, calcium silicate, magnesium silicate , At least one of diatomaceous earth and quartz sand. The first filling material may have a spherical shape, a substantially spherical shape, a dumbbell shape, or a rod shape.

  The second filling material is fiber particles having a particle size of 1 to 10,000 nm, preferably 100 to 5000 nm, and more preferably 300 to 3000 nm. The second filling material plays a reinforcing role in the separator and is a fiber particle. The fiber particles are one kind or a mixture of two or more kinds such as wollastonite fiber, glass fiber, lignin, cellulose nanofiber, acrylic fiber, polyamide fiber, polyester fiber, aramid fiber and polyimide fiber.

  Preferably, the modified nonwoven fabric base material is one or a mixture of two or more of polyester, polyolefin, nitrile polymer and polyimide. The first filling material is inorganic oxide particles. The second filling material is one type or a mixture of two or more types of wollastonite fiber, lignin, and cellulose.

  The separator for a new modified nonwoven fabric lithium ion battery and the manufacturing method thereof include the following steps a to f.

In step a, a non-woven fiber layer is manufactured, a high-melting material and a low-melting material are processed to manufacture a non-woven fiber layer, and the processing step is one of melt blown, spunbond, paper making, spunlace, piercing, hot rolling. Here, the weight of the high melting point material is 85 to 99.9% of the total weight of the manufactured nonwoven fabric fiber layer, and the rest is the low melting point material. By adjusting the parameters, the pore size and porosity of the nonwoven fiber layer can be controlled,
The high melting point material is one or more of polyester, polyolefin, nitrile polymer, aromatic polyimide, and polyether having a melting point ≧ 200 ° C.,
The low melting point material is polyolefin having a melting point of 50 to 199 ° C., polyvinyl alcohol, polystyrene, heat-adhesive polyester, or fluorine polymer.

In step b, producing a modified nonwoven substrate,
The nonwoven fabric fiber layer obtained in step a is melt crystallized, and the melt crystallizing process is performed by heating and melting the low melting point material at a temperature 0 to 10 ° C. higher than the melting point of the low melting point material used in step a. Then, it is a process of cooling and crystallizing. Since the melting temperature is 0 to 10 ° C. higher than the melting point of the low melting point material in step a, the low melting point material with a small weight ratio softens and melts, changes the original fiber type, and creates a flat and uniform surface. On the other hand, the high melting point material having a large weight ratio does not change because of its high temperature stability. When the heating is stopped and the temperature is lowered, the high-melting point substance is firmly bonded by the cooled crystal of the melted low-melting point melt, and the strength of the whole substrate is improved. Subsequently, the nonwoven fabric subjected to the melt crystallization treatment is dried to ensure that the moisture content of the nonwoven fabric is as low as possible.

  In step c, a filler pulp is produced and a drying process is performed on the first filler material and the second filler material. The organic polymer, the first solvent, and the second solvent were mixed at a weight ratio of 1: (5-50) :( 0.1-10), stirred and heated to a clear state, and then dried. The first filler material and / or the second filler material is added and mixed uniformly.

  The organic polymer is one type or a combination of two or more types such as a fluorine-based polymer, rubber, ester-based polymer, cellulose, and starch. The fluoropolymer includes, but is not limited to, polyvinylidene fluoride, polyvinylidene fluoride hexafluoropropylene, polytetrafluoroethylene, and polyvinylidene fluoride trichloroethylene. The rubber includes, but is not limited to, styrene butadiene rubber, carboxylated styrene butadiene rubber, nitrile butadiene rubber, and silicone rubber. Examples of the ester-based polymer include, but are not limited to, polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polyacrylic acid glyceride, methacrylic acid ethylene glycol ester, polyethylene vinyl acetate, and polyvinyl acetate. The cellulose includes, but is not limited to, cellulose acetate, cellulose acetate butyrate, cellulose propionate, cyanoethyl cellulose, carboxymethyl cellulose, and mixtures thereof. The starch includes, but is not limited to, cyanoethyl pullulan, pullulan and the like.

  The first solvent is one type or a mixture of two or more types of ketone solvents, amide solvents, and ester solvents. Ketone solvents include but are not limited to acetone, butanone and N-methylpyrrolidone. Amide solvents include, but are not limited to, N, N-dimethylacetamide, N, N-dimethylformamide. Ester solvents include, but are not limited to, triethyl phosphite, trimethyl phosphite, and ethyl acetate.

  The second solvent is one or a mixture of two or more of water, an alcohol solvent, and a halogenated hydrocarbon solvent. Examples of the alcohol solvent include, but are not limited to, methanol, ethanol, propanol, isopropanol, isobutyl alcohol, ethylene glycol, butyl alcohol, and glycerin. The halogenated hydrocarbon solvent includes, but is not limited to, chloroform and dichloromethane.

  The boiling point of the selected second solution is 10 ° C. or more higher than the boiling point of the first solvent. The stirring heating temperature is not higher than the boiling point of the first solvent, and is preferably lower by 10 ° C. or more than the boiling point of the first solvent. When the heating temperature is too high, the volatilization of the solvent is too early, so that the local temperature of the pulp becomes high and tends to lump.

  In step d, the nonwoven fabric is filled, and the filler pulp produced in step c is filled into the modified nonwoven fabric substrate produced in step b.

  In step e, the solvent is removed, and the nonwoven fabric fiber layer processed in step d is extracted or dried to obtain a spare nonwoven fabric lithium ion battery separator.

In step f, post-treatment is performed, and the preliminary nonwoven fabric lithium ion battery separator manufactured in step e is heated to a temperature 5-30 ° C. higher than the melting point of the organic polymer,
Alternatively, the third solvent is immersed in a third solvent, and the third solvent is one or a mixture of two or more of water, a ketone solvent, an amide solvent, an ester solvent, an alcohol solvent, and a halogenated hydrocarbon solvent.

  By step f, the organic polymer covers the filler material more tightly, reducing the moisture content of the separator and increasing the strength. In the process, creep occurs in the organic polymer and the pore structure of the coating layer changes. However, the pore structure of the coating layer does not change, and the separator does not undergo large thermal shrinkage. Furthermore, since the inorganic particles are covered with the organic polymer and the surface of most of the inorganic particles is isolated from the air, the water absorption of the inorganic particles is greatly reduced. The treated separator can retain a low water content after being stored in air for several months.

  The third solvent may be the same as or different from the first solvent, and is preferably acetone, water, or N, N-dimethyl sulfoxide. Such solvents can dissolve the organic polymer and thus change the pore structure of the coating but must affect the excellent performance of the separator.

  In order to improve the performance of the coated pulp, preferably, in step c, an appropriate auxiliary agent is added as necessary. The adjunct adjunct helps the film formation but should not adversely affect the battery system. The adjuvant includes one or more types such as a dispersant, an antifoaming agent, and a surfactant, but is not limited thereto.

  A commercially available dispersant may be sufficient as the said dispersing agent, For example, it is 1 type or multiple types, such as polyvinylpyrrolidone, sodium carboxymethylcellulose, sodium polyacrylate.

  The surfactant is a commercially available activator, and is, for example, one type or a plurality of types such as a fluorine-containing surfactant, a silicon-containing surfactant, and a polyether surfactant.

  The said antifoaming agent is a commercially available antifoaming agent, for example, 1 type or multiple types, such as natural fats and oils, a silicone type antifoaming agent, a higher fatty alcohol, and a polyether type antifoaming agent.

  Furthermore, in the step c, the ratio of the total weight of the first filling material and the second filling material and the weight of the organic polymer is (1: 5) to (5: 1), and the second filling material is It occupies 0-50% of the total weight of the first filler material and the second filler material.

  To improve the performance of the fabricated battery separator, after step f, additional mechanical processing is added or combined to the fabricated lithium ion battery separator as necessary, for example, hot One or more types of rolling, centrifugation and tension. When increasing the porosity, it may be considered to increase the tensioning process. When decreasing the porosity, it may be considered to increase rolling or centrifugation.

  The new lithium ion battery separator according to the present invention can realize the following technical effects. The unique nonwoven fabric base material can improve the strength of the separator, ensure winding workability, and improve the yield of the battery. The special organic polymer covering the inorganic granule structure can greatly reduce the water absorption of the battery separator and reduce the possibility of moisture entering the battery system. Therefore, the reaction between excess moisture and electrolyte prevents battery expansion and increases internal resistance. Furthermore, the magnification discharge performance and service life of the battery are improved. The present invention further provides a method for manufacturing a separator for a new lithium ion battery. The method is simple to operate, low in cost, and manufactured products have low moisture content, good chemical stability, and high mechanical strength, thus improving battery yield, service life and safety.

  Hereinafter, the present invention will be further described with reference to the drawings and specific embodiments.

FIG. 1 is a schematic configuration diagram of a separator for a modified nonwoven fabric lithium ion battery according to the first embodiment.

<First embodiment>
A non-woven fiber web layer is made by wet paper making using 95 g of high melting point PET fiber having a melting point of 250 ° C. and 5 g of low melting point PET fiber having a melting point of 150 ° C. By performing a melt crystallization treatment at a temperature of 155 ° C. on the nonwoven fiber web layer and then cooling, the porosity is 58%, the average pore diameter is 11 μm, the puncture strength is 3.0 N, 150 ° C. and In the case of 1 h, the modified nonwoven fabric substrate 1 having a heat shrinkage of 1% and a thickness of 16 μm can be manufactured.

  Filler 2 is prepared. The filler includes aluminum oxide and PVDF.

  The nonwoven fabric subjected to the melt crystallization treatment is dried, where the drying temperature is 90 ° C. and the time is 1 min. 40 g of aluminum oxide with a particle size of 250 nm is placed in a dry box, where the temperature is 100 ° C. and the time is 4 h.

  20 g of PVDF having a melting point of 165, 500 g of acetone and 20 g of ethyl alcohol are mixed and heated and stirred at 60 ° C. until a clear state is obtained. Dried aluminum oxide, 0.5 g of PVP and 1 g of a fluorinated surfactant are added to the mixed solution, and stirring is continued for 15 to 30 minutes to obtain a pre-dispersed pulp. The pulp is put into a dispersing device and dispersed for 15 to 20 minutes to obtain a filled pulp.

  Using a soaking method, fill the above-mentioned filled pulp into a PET-modified nonwoven fabric substrate having a bimodal melting point, leave it for 5 to 10 minutes, place it in a drying box, and dry for 10 to 20 minutes. A preliminary nonwoven fabric composite separator is obtained.

  The above-mentioned preliminary nonwoven fabric composite separator is hot-pressed at a temperature of 160 ° C. to obtain a modified nonwoven fabric lithium ion battery separator having a thickness of 20 μm according to the present invention. As shown in FIG. 1, the manufactured modified nonwoven fabric lithium ion battery separator includes a modified nonwoven fabric substrate 1 and a filler 2. The filler 2 is filled in the holes of the modified nonwoven fabric substrate 1 and extends outward to cover the entire modified nonwoven fabric substrate 1.

<Second embodiment>
The difference from the modified nonwoven fabric lithium ion battery separator according to the method of the first example is that only 0.5 g of a low melting point PET fiber having a melting point of 150 ° C. is added, the puncture strength is 2.2 N, and 150 ° C. And in the case of 1h, the nonwoven fabric base material whose heat shrinkage is 0.5% can be manufactured.

<Third embodiment>
The difference from the modified nonwoven fabric lithium ion battery separator according to the method of the first example is that only 16.8 g of low melting point PET fiber having a melting point of 150 ° C. is added, and the puncture strength is 3.2 N, 150 ° C. And in the case of 1h, it is a point which can manufacture the nonwoven fabric base material whose heat shrinkage is 5%.

<Fourth embodiment>
The difference from the modified nonwoven fabric lithium ion battery separator according to the method of the first embodiment is that the thickness of the filled separator and the thickness of the unfilled nonwoven fabric substrate are the same, and are 16 μm.

<Fifth embodiment>
The difference from the modified nonwoven fabric lithium-ion battery separator according to the method of the first embodiment is that a modified nonwoven fabric substrate is produced using a meltblown process.

<Sixth embodiment>
The difference from the modified nonwoven fabric lithium ion battery separator according to the method of the first example is that 40 g of aluminum oxide having a particle size of 250 nm is put in a dry box, where the temperature is 80 ° C. and the time is 1 min. Is a point.

<Seventh embodiment>
The difference from the modified nonwoven fabric lithium ion battery separator according to the method of the first example is that 20 g wollastonite fiber particles having a particle size of 1200 nm are added.

<Eighth embodiment>
The difference from the modified nonwoven fabric lithium ion battery separator according to the method of the first example is that PVDF-HFP having a melting point of 145 ° C. is selected as the organic polymer and butanone is selected as the first solvent.

<Ninth embodiment>
The difference from the modified nonwoven fabric lithium ion battery separator according to the method of the first embodiment is that magnesium hydroxide having a particle size of 800 nm is used as the first filling material.

<Tenth embodiment>
The difference from the modified nonwoven fabric lithium ion battery separator according to the method of the first embodiment is that in the post-treatment step, the preliminary nonwoven fabric composite separator is dipped in water for 1 to 5 minutes and then dried to modify the modified nonwoven fabric lithium ion according to the present invention. The battery separator can be manufactured.

<Eleventh embodiment>
The difference from the modified nonwoven fabric lithium-ion battery separator according to the method of the first embodiment is that the preliminary nonwoven fabric composite separator is hot pressed at a temperature of 180 ° C.

<First comparative example>
The difference from the lithium ion battery separator according to the method of the first embodiment is that a modified nonwoven fabric substrate is produced when a low melting point PET material at 150 ° C. is not added.

<Second Comparative Example>
The difference from the lithium ion battery separator according to the method of the first embodiment is that 24 g of a low melting point PET material having a melting point of 150 ° C. is added to produce a modified nonwoven fabric substrate.

<Third comparative example>
The difference from the lithium ion battery separator according to the method of the first embodiment is that the non-woven fabric substrate and the aluminum oxide are not dried.

<Fourth comparative example>
The difference from the lithium ion battery separator according to the method of the first embodiment is that no post-treatment process is performed.

<Fifth Comparative Example>
The difference from the lithium ion battery separator according to the method of the first embodiment is that a single layer PE film is used as a base material.

<Sixth comparative example>
It is an ordinary ceramic separator.

<Seventh comparative example>
It is an ordinary nonwoven fabric separator.

  Battery performance test

The positive electrode is made of lithium cobaltate LiCoO2, the negative electrode is made of graphite, and the battery electrolyte is a 1: 1: 1 volume ratio of ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC). the use, solute that is added to the electrolyte is lithium hexafluorophosphate in 1 mol / L LiPF _6. Battery performance evaluation is performed on Examples 1 to 6 and Comparative Examples 1 to 5, respectively.

  About moisture content test method and test results

The samples of each example are placed in a drying box at 85 ° C. and dried at different times (6 h, 12 h, 24 h, and 48 h, respectively), and then the moisture content test is performed on the samples. Table 1 shows the test results.

  According to the test results in Table 1, the separator of the present invention has lower heat shrink performance when compared with a normal ceramic separator. Compared with the first, second, fourth, and seventh comparative examples, the separator manufactured based on the specific high and low melting point characteristics of the nonwoven fabric substrate according to the present invention has lower heat shrink performance and sufficient piercing tensile strength. At the same time to ensure the separator battery processing yield and safety.

  According to the test results in Table 2, the water content of the separator of the present invention is lower than that of a conventional ceramic separator. Compared with the third, fourth and sixth comparative examples, the separator composed of the base material and the filling structure according to the present invention has a low processing water content and a structure in which the organic polymer covers the inorganic particles. Reduce the drying time.

  Test method and test result of insulation breakdown short circuit

  100 batteries are fabricated for each example. In battery fabrication, the battery cells are dried in a vacuum drying box at 85 ° C. for 24 hours, and then the insulation breakdown breakdown test is performed on the battery cells, and the number statistics are performed on the batteries tested at different voltages. Table 3 shows the test results.

  According to the test results in Table 3, the insulation resistance of the separator of the present invention is better than that of an ordinary nonwoven fabric separator, and the failure short-circuit test pass rate at a voltage of 250 V reaches 100%. The acceptance rate is 5%. Compared with the first and fourth comparative examples, the separator composed of the base material and the filler structure according to the present invention, the base material speciality and the coverage filler structure greatly improves the insulation resistance of the separator, Improve battery yield.

  Safety performance test methods and test results

  100 batteries are fabricated for each example. Perform battery safety performance tests and perform statistics on the number of batteries and the test status.

  About heat shock, it tests based on the method in Chinese national standard GB / T18287-2013, and makes a judgment standard that there is no liquid leak, it does not ignite, and an explosion does not occur.

  For piercing at room temperature, when charging at a constant current to a charge limit voltage of 4.2 V at a current of 0.5 C, conversion to a constant voltage charging is performed, and charging stops when the current drops to 0.02 C after 3.5 H The charged battery is pierced vertically at a speed of 21 to 40 mm / sec using an iron nail having a diameter of 3.0 to 8.0 mm, does not ignite, and no explosion occurs. This is the criterion.

  The short circuit is tested based on the method in Chinese national standard GB / T18287-2013, and it is determined that no ignition occurs, no explosion occurs, and the temperature of the outer surface is lower than 150 ° C.

  For overcharge, a test is conducted based on the method in Chinese national standard GB / T18287-2013, and it is determined that no ignition occurs and no explosion occurs.

Table 4 shows the test results.

  The test results in Table 4 indicate that the battery according to the separator of the present invention has a better expression on the safety performance test, and therefore the separator of the present invention has good high temperature stability and safety. When accidents such as thermal runaway and external force impact occur, accidents such as battery fires and explosions can be prevented more effectively.

  About electrical performance test methods and test results

  100 batteries are fabricated for each example. An electrical performance test is performed on the battery, and an average value of 10 battery test data is calculated and entered in Table 5.

  For magnification discharge, the test is performed based on the method in Chinese national standard GB / T18287-2013.

  Regarding the cycle performance, a charge / discharge cycle test is performed at a magnification of 1C using a performance test apparatus BS-9300, and a charge / discharge voltage range is 3 using a constant current constant voltage charge method (CC-CV) and a constant current discharge method. First, it is charged to 4.2 V with a constant current of 1 C, and then charged with a constant voltage of 4.2 V until the current is lower than 20 mA, and then the cut-off voltage is 3.0 V. Until a constant current of 1 C is discharged. In this way, cycle data is collected by performing 500 cycles.

  The internal resistance is tested based on the method in Chinese national standard GB / T18287-2013.

Table 5 shows the test results.

  According to the test results in Table 5, the battery using the separator of the present invention has a smaller internal resistance, and a higher rate discharge performance and cycle performance. The substrate and filler according to the present invention provide the separator with the present invention by providing the separator with a uniform thickness and pore size, good electrochemical stability, excellent liquid retention performance, and minimal water absorption. The battery has excellent magnification discharge performance and cycle life.

  The above-described embodiments are merely preferred embodiments of the present invention, and do not limit the scope of protection of the present invention. A person skilled in the art will be aware that all non-substantial changes and substitutions within the scope of the invention are all within the scope of protection of the invention.

Reference explanation

1 Modified nonwoven substrate 2 Filler

Claims (10)

A separator for a new modified non-woven lithium ion battery,
The separator comprises a modified nonwoven fabric substrate and a composite filler thereof,
In the modified nonwoven fabric substrate, uniformly arranged pores having a pore diameter of 1 to 50000 nm are distributed, and the porosity is 30 to 95%,
The modified nonwoven fabric base material includes a low melting point material and a high melting point material, the low melting point material is melt-crystallized, and the high melting point material is 85 to 99.9 of the total weight of the modified nonwoven fabric base material. a%, the remainder is a low melting point material, a polyester wherein the refractory material is a melting point of ≧ 200 ° C., polyolefins, nitrile polymers, formed by mixing one or more kinds of polyimides and polyether, said low melting point The material is formed by mixing one or more kinds of polyolefins having a melting point of 50 to 199 ° C., polyvinyl alcohol, heat-adhesive polyester, polystyrene, and fluoropolymer,
The filler combined with the modified nonwoven fabric substrate comprises an organic polymer and a first filler material, or a second filler material, or a mixture of the first filler material and the second filler material,
The organic polymer is a fluorine polymer, rubber, ester polymer, cellulose, or a combination of two or more types of starch,
The first filling material is inorganic particles having a particle size of 1 to 2000 nm, and the inorganic particles are one kind or a combination of two or more kinds of inorganic oxide nanoparticles, inorganic nitride nanoparticles, and ore nanoparticles. Yes,
The second filling material is a fiber particle having a particle diameter of 1 to 10,000 nm, and the fiber particle includes wollastonite fiber, glass fiber, lignin, cellulose nanofiber, acrylic fiber, polyamide fiber, polyester fiber, aramid fiber, and the like. One type of polyimide fiber or a combination of two or more types,
A new modified nonwoven fabric lithium-ion battery separator, wherein the filler is filled in the pores of the modified nonwoven fabric substrate. The filler extends outwardly from the inside of the modified nonwoven fabric substrate to cover the entire modified nonwoven fabric substrate,
The separator for a new type modified nonwoven fabric lithium ion battery according to claim 1, wherein the thickness of the separator is 1 to 10 times the thickness of the modified nonwoven fabric substrate.   The thickness of the said separator is 1-2 times the thickness of a modified nonwoven fabric base material, The separator for new type modified nonwoven fabric lithium ion batteries of Claim 2 characterized by the above-mentioned.   The new modified nonwoven fabric lithium ion battery according to claim 1, wherein the particle size of the first filling material is 10 to 1000 nm, and the particle size of the second filling material is 100 to 5000 nm. Separator for use.   2. The new type reforming according to claim 1, wherein in the melt crystallization treatment, the low melting point material is heated and melted at a temperature 0 to 10 ° C. higher than the melting point, and then cooled and crystallized. Non-woven lithium ion battery separator. A method for producing a separator for the new modified nonwoven fabric lithium ion battery according to any one of claims 1 to 5,
The manufacturing method includes the following steps a to f:
In step a, a nonwoven fiber layer is produced,
A high-melting-point material and a low-melting-point material are processed to produce a non-woven fiber layer, and the processing step is one of melt blown, spunbonding, wet papermaking, spunlace, piercing, and hot rolling. The weight of the melting point material is 85 to 99.9% of the total weight of the manufactured nonwoven fiber layer, and the rest is a low melting point material,
The high melting point material is one or more of polyester, polyolefin, nitrile polymer, polyimide and polyether having a melting point ≧ 200 ° C.,
The low melting point material is one or more kinds of polyolefin, polyvinyl alcohol, heat-adhesive polyester, polystyrene and fluoropolymer having a melting point of 50 to 199 ° C.,
In step b, producing a modified nonwoven substrate,
Melt crystallization treatment of the nonwoven fabric fiber layer obtained in step a,
The melt crystallization treatment is a process of heating and melting the low melting point material at a temperature 0 to 10 ° C. higher than the melting point of the low melting point material used in step a, and then cooling and crystallizing.
In step c, making a filler pulp,
Drying the first filler material and / or the second filler material, mixing the organic polymer, the first solvent and the second solvent in a weight ratio of 1: (5-50) :( 0.1-10); Stir and heat until clear, then add the dried first filler and / or second filler and mix uniformly,
The organic polymer is a fluorine polymer, rubber, ester polymer, cellulose, or a combination of two or more types of starch,
The first solvent is one or a mixture of a ketone solvent, an amide solvent and an ester solvent,
The second solvent is one or a mixture of two or more of water, alcohol solvent, halogenated hydrocarbon solvent,
In step d, filling the nonwoven fabric,
Filling the modified nonwoven fabric substrate produced from step b with the filler pulp produced in step c,
In step e, the solvent is removed,
Extracting or drying the nonwoven fabric fiber layer processed in step d to obtain a spare nonwoven fabric lithium ion battery separator,
In step f, post-processing is performed,
Heating the spare nonwoven fabric lithium ion battery separator produced in step e to a temperature 5-30 ° C. higher than the melting point of the organic polymer;
Alternatively, it is immersed in a third solvent, and the third solvent is a mixture of one or more of water, a ketone solvent, an amide solvent, an ester solvent, an alcohol solvent, and a halogenated hydrocarbon solvent.
A method for producing a separator for a new-type modified nonwoven fabric lithium ion battery, characterized in that In step c,
The ratio of the total weight of the first filling material and the second filling material to the weight of the organic polymer is (1: 5) to (5: 1),
The method for producing a separator for a new modified nonwoven fabric lithium ion battery according to claim 6, wherein the second filling material occupies 0 to 50% of the total weight of the first filling material and the second filling material.   The new type according to claim 6, wherein in step c, an auxiliary agent is added, and the auxiliary agent is one kind or a combination of two or more kinds of a dispersant, an antifoaming agent, and a surfactant. Manufacturing method of separator for modified non-woven lithium ion battery.   The method for producing a separator for a new modified nonwoven fabric lithium ion battery according to claim 6, wherein the filling in step d uses lamination, soaking, pressing, pouring, roll coating, knife coating or gravure coating. .   The manufactured new modified nonwoven fabric lithium ion battery separator is subjected to mechanical treatment, and the mechanical treatment is one or more kinds of hot rolling, centrifugal separation, and tension. 6. A method for producing a separator for a new modified nonwoven fabric lithium ion battery according to 6.