Lithium battery conductive adhesive and preparation method thereof

Abstract

The invention discloses a lithium battery conductive adhesive and a preparation method thereof, and relates to the field of adhesives. When the conductive adhesive for the lithium battery is prepared, 4, 4 '-diaminodiphenyl ketone and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide are subjected to a reaction, and a flame-retardant curing agent is prepared; the preparation method comprises the following steps: reacting a carbon nanotube with 3-chloromethyl thiophene, reducing, and reacting with a trichloromethane mixed solution of thiophene to prepare a polythiophene modified carbon nanotube; the preparation method comprises the following steps: enabling tetraethyl cyclotetrasiloxane and N, N-dimethyl aminopropyl dimethyl methoxy silane to react to prepare modified polysiloxane; diallyl bisphenol A diglycidyl ether, modified polysiloxane, a flame-retardant curing agent, polythiophene modified carbon nanotubes and azodiisobutyronitrile are subjected to a reaction, and the flame-retardant modified carbon nanotubes are prepared. The lithium battery conductive adhesive prepared by the invention has good flame retardant property, heat resistance, adhesive property and conductivity.

Description

Technical Field

[0001] The invention relates to the field of adhesives, and in particular to a lithium battery conductive adhesive and a preparation method thereof. Background Art

[0002] Conductive adhesive refers to a type of composite material composed of a polymer matrix with conductive fillers added, which has both bonding and conductive properties. The connection between traditional electronic components is mainly carried out through lead-tin solder. Due to its low melting point, good conductivity, low price and good stability, tin-lead solder has always been used as a conductive connection material for electronic packaging. However, the lead in discarded waste electronic products can easily enter people's drinking water systems through underground pipes and cause harm to the human nervous system, blood, cardiovascular and digestive systems. Therefore, conductive adhesive, as a lead-free adhesive, is an ideal alternative to lead-tin solder.

[0003] Conductive adhesive has the advantages of low processing temperature and mild use conditions, and is simple to use, environmentally friendly, and has little pollution to the environment and human body. Therefore, conductive adhesive is considered to be the next generation of ideal electronic packaging connection materials. However, compared with mature tin-lead solder, conductive adhesive has the disadvantages of low conductivity, low bonding strength and poor stability, which limits its wide application. The lithium battery conductive adhesive prepared by the present invention has good flame retardant properties, heat resistance, bonding properties and conductivity, and has good market prospects. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a lithium battery conductive adhesive to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A lithium battery conductive adhesive is provided. The conductive adhesive is prepared by reacting 4,4'-diaminobenzophenone with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to obtain a flame retardant curing agent; reacting carbon nanotubes with 3-chloromethylthiophene and reducing the reacted carbon nanotubes with a chloroform mixed solution of thiophene to obtain polythiophene-modified carbon nanotubes; reacting tetraethylcyclotetrasiloxane with N,N-dimethylaminopropyldimethylmethoxysilane to obtain modified polysiloxane; and reacting diallyl bisphenol A diglycidyl ether, modified polysiloxane, a flame retardant curing agent, polythiophene-modified carbon nanotubes and azobisisobutyronitrile to obtain the conductive adhesive.

[0007] A method for preparing a lithium battery conductive adhesive comprises the following steps:

[0008] (1) 4,4'-diaminobenzophenone and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide are mixed in a mass ratio of 1:(1-1.4), stirred at 400-600 r / min for 3-5 hours at 175-185° C., cooled to 95-105° C., added with toluene in an amount of 8-12 times the mass of 4,4'-diaminobenzophenone, stirred for 25-35 minutes, filtered, washed the precipitate with toluene for 3-5 times, and recrystallized with tetrahydrofuran to obtain a flame retardant curing agent;

[0009] (2) Mix carbon nanotubes and deionized water at a mass ratio of 1: (300-400) and ultrasonically disperse for 25-35 minutes, add 3-chloromethylthiophene ethanol solution at a mass ratio of 0.2-0.3 times the mass of deionized water, stir and reflux at 85-95° C. and 500-700 r / min for 20-24 hours, filter, ultrasonically reflux the filter cake with anhydrous ethanol for 3-5 minutes, filter, wash with anhydrous ethanol 3-5 times, dry at 80-90° C. for 4-6 hours, and obtain a modified carbon nanotube primary product; Mix the modified carbon nanotube primary product and deionized water at a mass ratio of 1: (400-600) and ultrasonically disperse for 25-35 minutes, add hydrazine hydrate at a mass ratio of 8-12 times the mass of the modified carbon nanotube primary product, stir and reflux at 85-95° C. and 500-700 r / min for 3 hours. Flow for 20 to 24 hours, filter, wash the filter residue with deionized water and anhydrous ethanol for 3 to 5 times, dry at 80 to 90°C for 4 to 6 hours to obtain modified carbon nanotubes; mix the modified carbon nanotube dispersion, anhydrous ferric chloride, and chloroform in the ratio of 1: (1.8 to 2.2): (7 to 9) by mass, stir at 400 to 600 r / min for 25 to 35 minutes in a nitrogen atmosphere, ice bath, and add a chloroform mixed solution of thiophene in an amount of 6 to 8 times the mass of anhydrous ferric chloride, stir for 2 to 4 hours, return to room temperature, continue stirring for 22 to 26 hours, add methanol in an amount of 2 to 4 times the mass of chloroform, continue stirring for 10 to 20 minutes, filter, wash the filter residue with chloroform for 3 to 5 times, and dry at 65 to 75°C for 4 to 6 hours to obtain polythiophene modified carbon nanotubes;

[0010] (3) Tetraethylcyclotetrasiloxane, N,N-dimethylaminopropyldimethylmethoxysilane and tetramethylammonium hydroxide silicon alkoxide are mixed in a mass ratio of 1: (0.6-0.8): (0.01-0.03), stirred at 100-200 r / min for 2-3 h at 80-90° C. under a nitrogen atmosphere, heated to 130-140° C. and continued to stir for 40-50 min, kept the temperature constant, and distilled at 0.1-0.3 MPa for 1-2 h to obtain polysiloxane; polysiloxane, bromohexane and isobutyl alcohol are mixed in a mass ratio of 1: (3-5): (15-25), stirred at 500-700 r / min for 22-26 h at 75-85° C., and distilled at 0.1-0.3 MPa for 1-2 h at 100-110° C. to obtain modified polysiloxane;

[0011] (4) Diallyl bisphenol A diglycidyl ether, modified polysiloxane, flame retardant curing agent, polythiophene modified carbon nanotubes, and azobisisobutyronitrile are mixed at a mass ratio of 1: (0.6-0.8): (1-1.2): (0.6-0.8): (0.02-0.04) at 35-45° C. to prepare a lithium battery conductive adhesive.

[0012] As an optimization, the reaction process of the flame retardant curing agent in step (1) is as follows:

[0013]

[0014] As an optimization, the ethanol solution of 3-chloromethylthiophene in step (2) is prepared by mixing 3-chloromethylthiophene and anhydrous ethanol in a mass ratio of 1:100 and ultrasonicating at a power of 350-450 W for 25-35 min.

[0015] As an optimization, the thiophene-chloroform mixed solution in step (2) is prepared by mixing thiophene, 3-vinylthiophene and chloroform in a mass ratio of 1: (0.3-0.5): (8-12).

[0016] As an optimization, the reaction process of the polythiophene-modified carbon nanotubes in step (2) is as follows:

[0017]

[0018] As an optimization, the reaction process of the modified polysiloxane in step (3) is as follows:

[0019]

[0020] As an optimization, the diallyl bisphenol A diglycidyl ether in step (3) is DADGEBA type diallyl bisphenol A diglycidyl ether, which was purchased from Laizhou Baichen Insulation Material Co., Ltd.

[0021] As an optimization, the lithium battery conductive glue in step (3) is prepared and used immediately.

[0022] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0023] When preparing the lithium battery conductive adhesive, the present invention comprises the following steps: reacting 4,4'-diaminobenzophenone with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to obtain a flame retardant curing agent; reacting carbon nanotubes with 3-chloromethylthiophene, reducing the carbon nanotubes, and then reacting the carbon nanotubes with a chloroform mixed solution of thiophene to obtain polythiophene-modified carbon nanotubes; reacting tetraethylcyclotetrasiloxane with N,N-dimethylaminopropyldimethylmethoxysilane to obtain modified polysiloxane; and reacting diallyl bisphenol A diglycidyl ether, modified polysiloxane, a flame retardant curing agent, polythiophene-modified carbon nanotubes, and azobisisobutyronitrile to obtain the lithium battery conductive adhesive.

[0024] Firstly, 4,4'-diaminobenzophenone reacts with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to prepare a flame retardant curing agent. The flame retardant compound 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is introduced, which has a good carbonization effect during combustion, and can effectively improve the flame retardant properties of the lithium battery conductive adhesive. The amino groups at both ends can react with the epoxy groups on diallyl bisphenol A diglycidyl ether to achieve a cross-linking curing effect. The carbon nanotubes are reacted with 3-chloromethylthiophene and reduced, and then reacted with a chloroform mixed solution of thiophene to obtain polythiophene-modified carbon nanotubes. A polythiophene structure with a double bond is introduced into the modified carbon nanotubes. On the one hand, polythiophene, as a conjugated structure, can effectively improve the conductivity of the conductive adhesive after being composited with the carbon nanotubes. On the other hand, the introduced double bonds can react with the double bonds on diallyl bisphenol A diglycidyl ether and the silicon hydrogen on the modified polysiloxane to form a complex cross-linking network, thereby improving the bonding performance of the conductive adhesive.

[0025] Secondly, tetraethylcyclotetrasiloxane and N,N-dimethylaminopropyldimethylmethoxysilane are reacted to obtain modified polysiloxane. On the one hand, the modified polysiloxane has abundant Si-O bonds, and the thermal stability of Si-O bonds is better than that of CC bonds. After cross-linking with diallyl bisphenol A diglycidyl ether, the heat resistance of the lithium battery conductive adhesive can be effectively improved; on the other hand, the quaternary ammonium structure formed by the reaction of N,N-dimethylaminopropyldimethylmethoxysilane and bromhexane on the modified polysiloxane can promote the migration of ions, thereby improving the conductivity of the lithium battery conductive adhesive; the abundant silicon-hydrogen bonds on the polysiloxane can react with the double bonds on the polythiophene-modified carbon nanotubes and diallyl bisphenol A diglycidyl ether to form a complex cross-linking network, thereby effectively improving the bonding performance of the conductive adhesive. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] A method for preparing a lithium battery conductive adhesive comprises the following steps:

[0029] (1) 4,4'-diaminobenzophenone and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were mixed in a mass ratio of 1:1, stirred at 400 r / min for 3 h at 175°C, cooled to 95°C, added with toluene in an amount 8 times the mass of 4,4'-diaminobenzophenone, stirred for 25 min, filtered, washed the precipitate with toluene for 3 to 5 times, and recrystallized with tetrahydrofuran to obtain a flame retardant curing agent;

[0030] (2) Mix carbon nanotubes and deionized water at a mass ratio of 1:300 and ultrasonically disperse for 25 minutes, add 0.2 times the mass of deionized water in ethanol solution of 3-chloromethylthiophene, stir and reflux at 85°C and 500 r / min for 20 hours, filter, ultrasonically treat the filter cake with anhydrous ethanol for 3 minutes, filter, wash with anhydrous ethanol three times, and dry at 80°C for 4 hours to obtain a modified carbon nanotube primary product; Mix the modified carbon nanotube primary product and deionized water at a mass ratio of 1:400, ultrasonically treat for 25 minutes at a power of 350 W, add 8 times the mass of the modified carbon nanotube primary product of hydrazine hydrate, stir at 85°C and 500 r / min, and reflux for 20 hours. Reflux for 20 hours, filter, wash the filter residue with deionized water and anhydrous ethanol for 3 times, dry at 80°C for 4 hours to obtain modified carbon nanotubes; mix the modified carbon nanotube dispersion, anhydrous ferric chloride, and chloroform in a mass ratio of 1:1.8:7, ice bath in a nitrogen atmosphere, stir at 400r / min for 25 minutes, add a chloroform mixed solution of thiophene with a mass of 6 times that of anhydrous ferric chloride, stir for 2 hours, return to room temperature, continue stirring for 22 hours, add methanol with a mass of 2 times that of chloroform, continue stirring for 10 minutes, filter, wash the filter residue with chloroform for 3 times, dry at 65°C for 4 hours, and obtain polythiophene modified carbon nanotubes;

[0031] (3) Tetraethylcyclotetrasiloxane, N,N-dimethylaminopropyldimethylmethoxysilane and tetramethylammonium hydroxide silicon alkoxide were mixed in a mass ratio of 1:0.6:0.01, stirred at 100 r / min for 2 h at 80°C under a nitrogen atmosphere, heated to 130°C and continued to stir for 40 min, kept the temperature constant, and distilled at 0.1 MPa for 1 h to obtain polysiloxane; polysiloxane, bromohexane and isobutyl alcohol were mixed in a mass ratio of 1:3:15, stirred at 500 r / min for 22 h at 75°C, and distilled at 100°C and 0.1 MPa for 1 h to obtain modified polysiloxane;

[0032] (4) Diallyl bisphenol A diglycidyl ether, modified polysiloxane, flame retardant curing agent, polythiophene modified carbon nanotubes, and azobisisobutyronitrile were mixed at a mass ratio of 1:0.6:1:0.6:0.02 at 35° C. to prepare a lithium battery conductive adhesive.

[0033] Example 2

[0034] A method for preparing a lithium battery conductive adhesive comprises the following steps:

[0035] (1) 4,4'-diaminobenzophenone and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were mixed in a mass ratio of 1:1.2, stirred at 180°C and 500 r / min for 4 hours, cooled to 100°C, added with toluene in an amount 10 times the mass of 4,4'-diaminobenzophenone, stirred for 30 minutes, filtered, washed the precipitate with toluene 4 times, and recrystallized with tetrahydrofuran to obtain a flame retardant curing agent;

[0036] (2) Mix carbon nanotubes and deionized water at a mass ratio of 1:350 and ultrasonically disperse for 30 minutes, add 3-chloromethylthiophene ethanol solution with a mass of 0.25 times that of deionized water, stir and reflux at 90°C and 600 r / min for 22 hours, filter, ultrasonically treat the filter cake with anhydrous ethanol for 4 minutes, filter, wash with anhydrous ethanol 4 times, and dry at 85°C for 5 hours to obtain modified carbon nanotubes. Mix the modified carbon nanotubes and deionized water at a mass ratio of 1:500, ultrasonically treat for 30 minutes at a power of 400 W, add hydrazine hydrate with a mass of 10 times that of the modified carbon nanotubes, stir and reflux at 90°C and 600 r / min for 22 hours, Filter, wash the filter residue with deionized water and anhydrous ethanol for 4 times, dry at 85°C for 5 hours to obtain modified carbon nanotubes; mix the modified carbon nanotube dispersion, anhydrous ferric chloride and chloroform in a mass ratio of 1:2:8, stir at 500r / min for 30 minutes in an ice bath under a nitrogen atmosphere, add a chloroform mixed solution of thiophene with a mass of 7 times that of anhydrous ferric chloride, stir for 3 hours, return to room temperature, continue stirring for 22 to 26 hours, add methanol with a mass of 2 to 4 times that of chloroform, continue stirring for 10 to 20 minutes, filter, wash the filter residue with chloroform for 3 to 5 times, dry at 65 to 75°C for 4 to 6 hours to obtain polythiophene modified carbon nanotubes;

[0037] (3) Tetraethylcyclotetrasiloxane, N,N-dimethylaminopropyldimethylmethoxysilane and tetramethylammonium hydroxide siliconate were mixed in a mass ratio of 1:0.7:0.02, stirred at 150 r / min at 85°C for 2.5 h under a nitrogen atmosphere, heated to 135°C and continued to stir for 45 min, kept the temperature constant, and distilled at 0.2 MPa for 1.5 h to obtain polysiloxane; polysiloxane, bromohexane and isobutyl alcohol were mixed in a mass ratio of 1:4:20, stirred at 600 r / min at 80°C for 24 h, and distilled at 105°C at 0.2 MPa for 1.5 h to obtain modified polysiloxane;

[0038] (4) Diallyl bisphenol A diglycidyl ether, modified polysiloxane, flame retardant curing agent, polythiophene modified carbon nanotubes, and azobisisobutyronitrile were mixed at a mass ratio of 1:0.7:1.1:0.7:0.03 at 40° C. to prepare a lithium battery conductive adhesive.

[0039] Example 3

[0040] A method for preparing a lithium battery conductive adhesive comprises the following steps:

[0041] (1) 4,4'-diaminobenzophenone and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were mixed in a mass ratio of 1:1.4, stirred at 185°C and 600 r / min for 5 hours, cooled to 105°C, added with toluene in an amount 12 times the mass of 4,4'-diaminobenzophenone, stirred for 35 minutes, filtered, washed the precipitate with toluene 5 times, and recrystallized with tetrahydrofuran to obtain a flame retardant curing agent;

[0042] (2) Mix carbon nanotubes and deionized water at a mass ratio of 1:400 and ultrasonically disperse for 35 minutes, add 0.3 times the mass of deionized water in ethanol solution of 3-chloromethylthiophene, stir and reflux at 95°C and 700 r / min for 24 hours, filter, ultrasonically treat the filter cake with anhydrous ethanol for 5 minutes, filter, wash with anhydrous ethanol 5 times, and dry at 90°C for 6 hours to obtain a modified carbon nanotube primary product; mix the modified carbon nanotube primary product and deionized water at a mass ratio of 1:600, ultrasonically treat for 35 minutes at a power of 450 W, add 12 times the mass of the modified carbon nanotube primary product of hydrazine hydrate, stir at 95°C and 700 r / min, and reflux for 24 hours. Reflux for 24 hours, filter, wash the filter residue with deionized water and anhydrous ethanol for 5 times, dry at 90°C for 6 hours to obtain modified carbon nanotubes; mix the modified carbon nanotube dispersion, anhydrous ferric chloride, and chloroform in a mass ratio of 1:2.2:9, stir at 600r / min for 35 minutes in an ice bath under a nitrogen atmosphere, add a chloroform mixed solution of thiophene with an amount of 8 times the mass of anhydrous ferric chloride, stir for 4 hours, return to room temperature, continue stirring for 26 hours, add methanol with an amount of 4 times the mass of chloroform, continue stirring for 20 minutes, filter, wash the filter residue with chloroform for 5 times, dry at 75°C for 6 hours to obtain polythiophene modified carbon nanotubes;

[0043] (3) Tetraethylcyclotetrasiloxane, N,N-dimethylaminopropyldimethylmethoxysilane and tetramethylammonium hydroxide silicon alkoxide were mixed in a mass ratio of 1:0.8:0.03, stirred at 200 r / min at 90°C for 3 h under a nitrogen atmosphere, heated to 140°C and continued to stir for 50 min, kept the temperature constant, and distilled at 0.3 MPa for 2 h to obtain polysiloxane; polysiloxane, bromohexane and isobutyl alcohol were mixed in a mass ratio of 1:5:25, stirred at 700 r / min at 85°C for 26 h, and distilled at 110°C at 0.3 MPa for 2 h to obtain modified polysiloxane;

[0044] (4) Diallyl bisphenol A diglycidyl ether, modified polysiloxane, flame retardant curing agent, polythiophene modified carbon nanotubes, and azobisisobutyronitrile were mixed at a mass ratio of 1:0.8:1.2:0.8:0.04 at 45° C. to prepare a lithium battery conductive adhesive.

[0045] Comparative Example 1

[0046] A method for preparing a lithium battery conductive adhesive comprises the following steps:

[0047] (1) Mix carbon nanotubes and deionized water at a mass ratio of 1:350 and ultrasonically disperse for 30 minutes, add 3-chloromethylthiophene ethanol solution with a mass ratio of 0.25 times that of deionized water, stir and reflux at 90°C and 600 r / min for 22 hours, filter, ultrasonically treat the filter cake with anhydrous ethanol for 4 minutes, filter, wash with anhydrous ethanol 4 times, and dry at 85°C for 5 hours to obtain a modified carbon nanotube primary product; mix the modified carbon nanotube primary product and deionized water at a mass ratio of 1:500, ultrasonically treat for 30 minutes at a power of 400 W, add hydrazine hydrate with a mass ratio of 10 times that of the modified carbon nanotube primary product, stir and reflux at 90°C and 600 r / min for 22 hours, Filter, wash the filter residue with deionized water and anhydrous ethanol for 4 times, dry at 85°C for 5 hours to obtain modified carbon nanotubes; mix the modified carbon nanotube dispersion, anhydrous ferric chloride and chloroform in a mass ratio of 1:2:8, stir at 500r / min for 30 minutes in an ice bath under a nitrogen atmosphere, add a chloroform mixed solution of thiophene with a mass of 7 times that of anhydrous ferric chloride, stir for 3 hours, return to room temperature, continue stirring for 22 to 26 hours, add methanol with a mass of 2 to 4 times that of chloroform, continue stirring for 10 to 20 minutes, filter, wash the filter residue with chloroform for 3 to 5 times, dry at 65 to 75°C for 4 to 6 hours to obtain polythiophene modified carbon nanotubes;

[0048] (2) Tetraethylcyclotetrasiloxane, N,N-dimethylaminopropyldimethylmethoxysilane and tetramethylammonium hydroxide siliconate were mixed in a mass ratio of 1:0.7:0.02, stirred at 150 r / min at 85°C for 2.5 h under a nitrogen atmosphere, heated to 135°C and continued to stir for 45 min, kept the temperature constant, and distilled at 0.2 MPa for 1.5 h to obtain polysiloxane; polysiloxane, bromohexane and isobutyl alcohol were mixed in a mass ratio of 1:4:20, stirred at 600 r / min at 80°C for 24 h, and distilled at 105°C at 0.2 MPa for 1.5 h to obtain modified polysiloxane;

[0049] (3) Diallyl bisphenol A diglycidyl ether, modified polysiloxane, diaminodiphenylmethane, polythiophene-modified carbon nanotubes, and azobisisobutyronitrile were mixed at a mass ratio of 1:0.7:1.1:0.7:0.03 at 40° C. to prepare a lithium battery conductive adhesive.

[0050] Comparative Example 2

[0051] A method for preparing a lithium battery conductive adhesive comprises the following steps:

[0052] (1) 4,4'-diaminobenzophenone and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were mixed in a mass ratio of 1:1.2, stirred at 180°C and 500 r / min for 4 hours, cooled to 100°C, added with toluene in an amount 10 times the mass of 4,4'-diaminobenzophenone, stirred for 30 minutes, filtered, washed the precipitate with toluene 4 times, and recrystallized with tetrahydrofuran to obtain a flame retardant curing agent;

[0053] (2) Tetraethylcyclotetrasiloxane, N,N-dimethylaminopropyldimethylmethoxysilane and tetramethylammonium hydroxide silicon alkoxide were mixed in a mass ratio of 1:0.7:0.02, stirred at 150 r / min at 85°C for 2.5 h under a nitrogen atmosphere, heated to 135°C and continued to stir for 45 min, kept the temperature constant, and distilled at 0.2 MPa for 1.5 h to obtain polysiloxane; polysiloxane, bromohexane and isobutyl alcohol were mixed in a mass ratio of 1:4:20, stirred at 600 r / min at 80°C for 24 h, and distilled at 105°C at 0.2 MPa for 1.5 h to obtain modified polysiloxane;

[0054] (3) Diallyl bisphenol A diglycidyl ether, modified polysiloxane, flame retardant curing agent, carbon nanotubes, and azobisisobutyronitrile were mixed at a mass ratio of 1:0.7:1.1:0.7:0.03 at 40° C. to prepare a lithium battery conductive adhesive.

[0055] Comparative Example 3

[0056] A method for preparing a lithium battery conductive adhesive comprises the following steps:

[0057] (1) 4,4'-diaminobenzophenone and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were mixed in a mass ratio of 1:1.2, stirred at 180°C and 500 r / min for 4 hours, cooled to 100°C, added with toluene in an amount 10 times the mass of 4,4'-diaminobenzophenone, stirred for 30 minutes, filtered, washed the precipitate with toluene 4 times, and recrystallized with tetrahydrofuran to obtain a flame retardant curing agent;

[0058] (2) Mix carbon nanotubes and deionized water at a mass ratio of 1:350 and ultrasonically disperse for 30 minutes, add 3-chloromethylthiophene ethanol solution with a mass of 0.25 times that of deionized water, stir and reflux at 90°C and 600 r / min for 22 hours, filter, ultrasonically treat the filter cake with anhydrous ethanol for 4 minutes, filter, wash with anhydrous ethanol 4 times, and dry at 85°C for 5 hours to obtain modified carbon nanotubes. Mix the modified carbon nanotubes and deionized water at a mass ratio of 1:500, ultrasonically treat for 30 minutes at a power of 400 W, add hydrazine hydrate with a mass of 10 times that of the modified carbon nanotubes, stir and reflux at 90°C and 600 r / min for 22 hours, Filter, wash the filter residue with deionized water and anhydrous ethanol for 4 times, dry at 85°C for 5 hours to obtain modified carbon nanotubes; mix the modified carbon nanotube dispersion, anhydrous ferric chloride and chloroform in a mass ratio of 1:2:8, stir at 500r / min for 30 minutes in an ice bath under a nitrogen atmosphere, add a chloroform mixed solution of thiophene with a mass of 7 times that of anhydrous ferric chloride, stir for 3 hours, return to room temperature, continue stirring for 22 to 26 hours, add methanol with a mass of 2 to 4 times that of chloroform, continue stirring for 10 to 20 minutes, filter, wash the filter residue with chloroform for 3 to 5 times, dry at 65 to 75°C for 4 to 6 hours to obtain polythiophene modified carbon nanotubes;

[0059] (3) Tetraethylcyclotetrasiloxane, n-butyldimethylmethoxysilane and tetramethylammonium hydroxide silicon alkoxide were mixed in a mass ratio of 1:0.7:0.02, stirred at 85°C and 150 r / min for 2.5 h under a nitrogen atmosphere, heated to 135°C and continued to stir for 45 min, kept the temperature constant, and distilled at 0.2 MPa for 1.5 h to obtain polysiloxane;

[0060] (4) Diallyl bisphenol A diglycidyl ether, polysiloxane, flame retardant curing agent, polythiophene modified carbon nanotubes, and azobisisobutyronitrile were mixed at a mass ratio of 1:0.7:1.1:0.7:0.03 at 40° C. to prepare a lithium battery conductive adhesive.

[0061] Comparative Example 4

[0062] A method for preparing a lithium battery conductive adhesive comprises the following steps:

[0063] (1) 4,4'-diaminobenzophenone and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were mixed in a mass ratio of 1:1.2, stirred at 180°C and 500 r / min for 4 hours, cooled to 100°C, added with toluene in an amount 10 times the mass of 4,4'-diaminobenzophenone, stirred for 30 minutes, filtered, washed the precipitate with toluene 4 times, and recrystallized with tetrahydrofuran to obtain a flame retardant curing agent;

[0064] (2) Mix carbon nanotubes and deionized water at a mass ratio of 1:350 and ultrasonically disperse for 30 minutes, add 3-chloromethylthiophene ethanol solution with a mass of 0.25 times that of deionized water, stir and reflux at 90°C and 600 r / min for 22 hours, filter, ultrasonically treat the filter cake with anhydrous ethanol for 4 minutes, filter, wash with anhydrous ethanol 4 times, and dry at 85°C for 5 hours to obtain modified carbon nanotubes. Mix the modified carbon nanotubes and deionized water at a mass ratio of 1:500, ultrasonically treat for 30 minutes at a power of 400 W, add hydrazine hydrate with a mass of 10 times that of the modified carbon nanotubes, stir and reflux at 90°C and 600 r / min for 22 hours, Filter, wash the filter residue with deionized water and anhydrous ethanol for 4 times, dry at 85°C for 5 hours to obtain modified carbon nanotubes; mix the modified carbon nanotube dispersion, anhydrous ferric chloride and chloroform in a mass ratio of 1:2:8, stir at 500r / min for 30 minutes in an ice bath under a nitrogen atmosphere, add a chloroform mixed solution of thiophene with a mass of 7 times that of anhydrous ferric chloride, stir for 3 hours, return to room temperature, continue stirring for 22 to 26 hours, add methanol with a mass of 2 to 4 times that of chloroform, continue stirring for 10 to 20 minutes, filter, wash the filter residue with chloroform for 3 to 5 times, dry at 65 to 75°C for 4 to 6 hours to obtain polythiophene modified carbon nanotubes;

[0065] (3) Diallyl bisphenol A diglycidyl ether, flame retardant curing agent, polythiophene modified carbon nanotubes, and azobisisobutyronitrile were mixed at a mass ratio of 1:1.1:0.7:0.03 at 40° C. to prepare a lithium battery conductive adhesive.

[0066] Test Example 1

[0067] Flame retardant properties: The lithium battery conductive adhesives obtained in each example and the comparative example were tested for limiting oxygen index according to GB / T2406. The results are shown in Table 1.

[0068] Table 1

[0069] Limiting oxygen index (%) Limiting oxygen index (%) Example 1 36.4 Comparative Example 1 17.6 Example 2 36.8 Comparative Example 2 36.1 Example 3 36.7 Comparative Example 3 35.7 Comparative Example 4 18.3

[0070] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 1, it can be found that the lithium battery conductive adhesive prepared by the present invention has good flame retardant properties.

[0071] By comparison, the limiting oxygen index of Examples 1 to 3 is significantly greater than that of Comparative Example 1, indicating that the flame retardant curing agent prepared by the reaction of 4,4'-diaminobenzophenone and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide introduces the flame retardant compound 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, which has a good carbonization effect during combustion, and can effectively improve the flame retardant properties of the lithium battery conductive adhesive; the limiting oxygen index of Examples 1 to 3 is significantly greater than that of Comparative Example 4, indicating that the modified polysiloxane, as a long chain of organic silicon, can form a carbon layer structure during the combustion process that can hinder the diffusion of oxygen into the combustion zone, thereby achieving a good flame retardant effect and improving the flame retardant properties of the lithium battery conductive adhesive.

[0072] Test Example 2

[0073] Bonding performance: The shear test piece was bonded by single overlap with a bonding area of ​​20×15 mm. The test piece was then placed in a fixture, fixed and subjected to a certain pressure, and cured at 150°C for 30 min. The shear strength of the lithium battery conductive adhesive of each embodiment and the comparative example was tested according to the GB-7124 adhesive tensile shear strength test method.

[0074] Heat resistance: The shear test piece was bonded in a single overlap manner with a bonding area of ​​20×15 mm, and then the test piece was placed in a fixture, fixed and a certain pressure was applied, and cured at 150°C for 30 min. The test temperature was set to 100°C, and the shear strength of the lithium battery conductive adhesive of each embodiment and comparative example was tested according to the GJB-444 adhesive high temperature tensile shear strength test method. The results are shown in Table 2.

[0075] Table 2

[0076]

[0077] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 2, it can be found that the lithium battery conductive adhesive prepared by the present invention has good bonding performance and heat resistance.

[0078] By comparison, the shear strength 2 of Examples 1 to 3 is significantly greater than the shear strength 1 of Comparative Example 2, indicating that the double bonds introduced by 3-vinylthiophene on the polythiophene-modified carbon nanotubes can react with the silicon-hydrogen bonds on the polysiloxane and the double bonds on diallyl bisphenol A diglycidyl ether to form stable crosslinks, thereby helping the conductive adhesive to form a complex network structure and improving the bonding performance of the conductive adhesive; the shear strength 1 of Examples 1 to 3 is significantly greater than the shear strength 1 of Comparative Example 4, indicating that the abundant silicon-hydrogen bonds on the modified polysiloxane can react with the double bonds on the polythiophene-modified carbon nanotubes and diallyl bisphenol A diglycidyl ether to form a complex crosslinking network, thereby effectively improving the bonding performance of the conductive adhesive.

[0079] By comparison, the shear strength 2 of Example 4 is significantly smaller than the shear strength 1 of Comparative Example 4, indicating that the modified polysiloxane has abundant Si-O bonds, and the thermal stability of Si-O bonds is better than that of CC bonds. After cross-linking with diallyl bisphenol A diglycidyl ether, the heat resistance of the lithium battery conductive adhesive can be effectively improved.

[0080] Test Example 3

[0081] Conductivity: The lithium battery conductive glue obtained in each embodiment and the comparative example were used in accordance with the national military standard GJB548A-1996 method 5011 to make a mold on a 170-mesh polyester screen, and then printed on a glass slide using a screen printer. The slide was cleaned with anhydrous ethanol, dried, and sealed for storage. The printed slide was placed in an oven for curing. After curing, when the conductive glue was cooled, the thickness of the conductive glue was measured with a micrometer, the width of the conductive glue was measured with a vernier caliper, and the resistance was directly measured with a DC digital resistance tester. According to the formula (where R is the measured resistance; w is the width of the glue layer; t is the thickness of the glue layer; L is the length of the glue layer) calculate the volume resistivity. The results are shown in Table 3.

[0082] Table 3

[0083] Volume resistivity (Ω·cm) Volume resistivity (Ω·cm) Example 1 <![CDATA[4.11×10 -5 ]]> Comparative Example 1 <![CDATA[4.53×10 -5 ]]> Example 2 <![CDATA[3.97×10 -5 ]]> Comparative Example 2 <![CDATA[9.88×10 -4 ]]> Example 3 <![CDATA[4.85×10 -5 ]]> Comparative Example 3 <![CDATA[1.14×10 -4 ]]> Comparative Example 4 <![CDATA[4.61×10 -5 ]]>

[0084] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 3, it can be found that the lithium battery conductive adhesive prepared by the present invention has good conductivity.

[0085] By comparison, the volume resistivity of Examples 1 to 3 is significantly lower than that of Comparative Example 2, indicating that polythiophene-modified carbon nanotubes are prepared by compounding polythiophene on carbon nanotubes. Polythiophene, as an organic polymer with a conjugated structure, has good electrical conductivity. After being compounded with carbon nanotubes, the conductivity of the conductive adhesive can be effectively improved; the volume resistivity of Examples 1 to 3 is significantly lower than that of Comparative Example 4, indicating that the quaternary ammonium structure formed by the reaction of N,N-dimethylaminopropyldimethylmethoxysilane and bromhexane on the modified polysiloxane can promote the migration of ions, thereby improving the conductivity of the conductive adhesive for lithium batteries.

[0086] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A lithium battery conductive adhesive, characterized in that: The lithium battery conductive adhesive is prepared by mixing diallyl bisphenol A diglycidyl ether, modified polysiloxane, flame retardant curing agent, polythiophene modified carbon nanotubes and azobisisobutyronitrile; The modified polysiloxane is prepared by reacting tetraethylcyclotetrasiloxane, N,N-dimethylaminopropyldimethylmethoxysilane and tetramethylammonium hydroxide silicon alkoxide and quaternizing with hexyl bromide; The polythiophene modified carbon nanotubes are prepared by firstly reacting carbon nanotubes with 3-chloromethylthiophene and reducing them to obtain modified carbon nanotubes; and then reacting with a chloroform mixed solution of thiophene to obtain the modified carbon nanotubes.

2. A method for preparing a lithium battery conductive adhesive, characterized in that: The method comprises the following preparation steps: (1) 4,4'-diaminobenzophenone and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide are mixed in a mass ratio of 1:(1-1.4), stirred at 175-185°C and 400-600 r / min for 3-5 hours, cooled to 95-105°C, added with toluene in an amount of 8-12 times the mass of 4,4'-diaminobenzophenone, stirred for 25-35 minutes, filtered, washed the precipitate with toluene for 3-5 times, and recrystallized with tetrahydrofuran to obtain a flame retardant curing agent; (2) Mix carbon nanotubes and deionized water at a mass ratio of 1: (300-400), ultrasonically disperse at a power of 350-450 W for 25-35 min, add 0.2-0.3 times the mass of deionized water in ethanol solution of 3-chloromethylthiophene, stir and reflux at 85-95° C. and 500-700 r / min for 20-24 h, filter, ultrasonically disperse the filter cake with anhydrous ethanol for 3-5 min, filter, wash with anhydrous ethanol 3-5 times, dry at 80-90° C. for 4-6 h, and obtain a modified carbon nanotube primary product; Mix the modified carbon nanotube primary product and deionized water at a mass ratio of 1: (400-600) and ultrasonically disperse for 25-35 min, add 8-12 times the mass of the modified carbon nanotube primary product in hydrazine hydrate, and stir at 85-95° C. and 500-700 r / m in stirring and refluxing for 20 to 24 hours, filtering, washing the filter residue with deionized water and anhydrous ethanol for 3 to 5 times, drying at 80 to 90°C for 4 to 6 hours, and obtaining modified carbon nanotubes; mixing the modified carbon nanotube dispersion, anhydrous ferric chloride, and chloroform in a mass ratio of 1: (1.8 to 2.2): (7 to 9), stirring at 400 to 600 r / min for 25 to 35 minutes in a nitrogen atmosphere, ice bathing, and adding a chloroform mixed solution of thiophene in an amount of 6 to 8 times the mass of anhydrous ferric chloride, stirring for 2 to 4 hours, returning to room temperature, continuing to stir for 22 to 26 hours, adding methanol in an amount of 2 to 4 times the mass of chloroform, continuing to stir for 10 to 20 minutes, filtering, washing the filter residue with chloroform for 3 to 5 times, and drying at 65 to 75°C for 4 to 6 hours to obtain polythiophene modified carbon nanotubes; (3) Tetraethylcyclotetrasiloxane, N,N-dimethylaminopropyldimethylmethoxysilane and tetramethylammonium hydroxide silicon alkoxide are mixed in a mass ratio of 1: (0.6-0.8): (0.01-0.03), stirred at 100-200 r / min for 2-3 h at 80-90° C. under a nitrogen atmosphere, heated to 130-140° C. and continued to stir for 40-50 min, kept the temperature constant, and distilled at 0.1-0.3 MPa for 1-2 h to obtain polysiloxane; polysiloxane, bromohexane and isobutyl alcohol are mixed in a mass ratio of 1: (3-5): (15-25), stirred at 500-700 r / min for 22-26 h at 75-85° C., and distilled at 0.1-0.3 MPa for 1-2 h at 100-110° C. to obtain modified polysiloxane; (4) Diallyl bisphenol A diglycidyl ether, modified polysiloxane, flame retardant curing agent, polythiophene modified carbon nanotubes, and azobisisobutyronitrile are mixed at a mass ratio of 1: (0.6-0.8): (1-1.2): (0.6-0.8): (0.02-0.04) at 35-45° C. to prepare a lithium battery conductive adhesive.

3. The method for preparing a lithium battery conductive adhesive according to claim 2, characterized in that: The reaction process of the flame retardant curing agent in step (1) is as follows:

4. The method for preparing a lithium battery conductive adhesive according to claim 2, characterized in that: The ethanol solution of 3-chloromethylthiophene in step (2) is prepared by mixing 3-chloromethylthiophene and anhydrous ethanol in a mass ratio of 1:100 and ultrasonically treating the mixture at a power of 350 to 450 W for 25 to 35 minutes.

5. The method for preparing a lithium battery conductive adhesive according to claim 2, characterized in that: The thiophene-chloroform mixed solution in step (2) is prepared by mixing thiophene, 3-vinylthiophene and chloroform in a mass ratio of 1: (0.3-0.5): (8-12).

6. The method for preparing a lithium battery conductive adhesive according to claim 2, characterized in that: The reaction process of polythiophene-modified carbon nanotubes in step (2) is as follows:

7. The method for preparing a lithium battery conductive adhesive according to claim 2, characterized in that: The reaction process of the modified polysiloxane in step (3) is as follows:

8. The method for preparing a lithium battery conductive adhesive according to claim 2, characterized in that: The diallyl bisphenol A diglycidyl ether in step (3) is DADGEBA type diallyl bisphenol A diglycidyl ether.

9. The method for preparing a lithium battery conductive adhesive according to claim 2, characterized in that: The lithium battery conductive glue in step (3) is prepared and used immediately.

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