CN118109140A - Conductive composite adhesive, preparation method, electrode plate and application - Google Patents
Conductive composite adhesive, preparation method, electrode plate and application Download PDFInfo
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- CN118109140A CN118109140A CN202410534122.2A CN202410534122A CN118109140A CN 118109140 A CN118109140 A CN 118109140A CN 202410534122 A CN202410534122 A CN 202410534122A CN 118109140 A CN118109140 A CN 118109140A
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- attapulgite
- styrene
- polythiophene
- butadiene rubber
- conductive composite
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- 239000002131 composite material Substances 0.000 title claims abstract description 51
- 239000000853 adhesive Substances 0.000 title claims abstract description 41
- 230000001070 adhesive effect Effects 0.000 title claims abstract description 41
- 238000002360 preparation method Methods 0.000 title abstract description 6
- 229960000892 attapulgite Drugs 0.000 claims abstract description 49
- 229910052625 palygorskite Inorganic materials 0.000 claims abstract description 49
- 229920000123 polythiophene Polymers 0.000 claims abstract description 45
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 44
- 229910021389 graphene Inorganic materials 0.000 claims abstract description 41
- 229920003048 styrene butadiene rubber Polymers 0.000 claims abstract description 40
- 239000000203 mixture Substances 0.000 claims abstract description 28
- 239000011230 binding agent Substances 0.000 claims description 30
- 238000002156 mixing Methods 0.000 claims description 20
- 239000011149 active material Substances 0.000 claims description 15
- 238000005096 rolling process Methods 0.000 claims description 13
- 239000002245 particle Substances 0.000 claims description 12
- 235000011837 pasties Nutrition 0.000 claims description 10
- 239000000843 powder Substances 0.000 claims description 9
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 8
- 229910052744 lithium Inorganic materials 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 8
- 238000001125 extrusion Methods 0.000 claims description 7
- 238000000227 grinding Methods 0.000 claims description 4
- 238000002844 melting Methods 0.000 claims description 4
- 230000008018 melting Effects 0.000 claims description 4
- 238000005469 granulation Methods 0.000 claims description 3
- 230000003179 granulation Effects 0.000 claims description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 23
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 23
- 229920000642 polymer Polymers 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 11
- 230000003247 decreasing effect Effects 0.000 description 8
- 239000013543 active substance Substances 0.000 description 6
- 239000011888 foil Substances 0.000 description 6
- 238000011056 performance test Methods 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 4
- YTPLMLYBLZKORZ-UHFFFAOYSA-N Thiophene Chemical group C=1C=CSC=1 YTPLMLYBLZKORZ-UHFFFAOYSA-N 0.000 description 4
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 4
- 239000000523 sample Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 238000009831 deintercalation Methods 0.000 description 2
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 239000007773 negative electrode material Substances 0.000 description 2
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 2
- 239000007774 positive electrode material Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910001290 LiPF6 Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000007767 bonding agent Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000021615 conjugation Effects 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- 238000000840 electrochemical analysis Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 229910021385 hard carbon Inorganic materials 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000004005 microsphere Substances 0.000 description 1
- 238000007719 peel strength test Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910021384 soft carbon Inorganic materials 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
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- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses a conductive composite adhesive, a preparation method, an electrode slice and application thereof, which relate to the technical field of polymer conductive adhesives and are prepared from the following components in parts by weight: 100 parts of a mixture of styrene-butadiene rubber and polythiophene; 0.2-0.8 parts of attapulgite; 0.4-1 part of graphene oxide; wherein, in the mixture of the styrene-butadiene rubber and the polythiophene, the styrene-butadiene rubber accounts for 80-90 wt%. According to the invention, the styrene-butadiene rubber with conductivity and the polythiophene are adopted, and the toughness of the styrene-butadiene rubber and the rigidity of the polythiophene are combined, so that the peeling strength of the electrode plate is improved; the attapulgite is added, a rod-shaped structure of the attapulgite forms a channel between the mixture of the styrene-butadiene rubber and the polythiophene, and the attapulgite has wider porous channels, so that electrons and lithium ions can move conveniently; graphene oxide is added to be embedded into a porous channel of the attapulgite, so that the movement speed of electrons and lithium ions is accelerated.
Description
Technical Field
The invention relates to the technical field of polymer conductive adhesives, in particular to a conductive composite adhesive, a preparation method, an electrode plate and application.
Background
In recent years, a novel dry electrode manufacturing technology is developed, an electrode film is prepared by adopting a solvent-free method and then is bonded with a current collector to form an electrode, the method is environment-friendly, the solvent is not required to be evaporated, the cost is greatly reduced, the dry electrode is not required to use the solvent in the manufacturing process, and the binder exists in a fiber state or a sheet shape, so that the influence on the internal contact among active material particles is reduced, and the conductivity and the specific discharge capacity of the electrode are improved.
However, due to the non-conductive property of the adhesive, the internal resistance of the electrode plate can be improved when the addition amount of the adhesive is increased; especially, when the adhesive is between the foil body and the active substance, the interface impedance between the foil body and the active substance is increased; if the addition amount of the binder is reduced, the bonding effect between the active material and the foil body is poor, and powder is easy to fall off after multiple cycles.
Disclosure of Invention
In order to solve at least one technical problem, a binder with good conductivity is developed, and the influence on the performance of an electrode plate is reduced.
On one hand, the conductive composite adhesive provided by the invention is prepared from the following components in parts by weight:
100 parts of a mixture of styrene-butadiene rubber and polythiophene;
0.2-0.8 parts of attapulgite;
0.4-1 part of graphene oxide;
wherein, in the mixture of the styrene-butadiene rubber and the polythiophene, the styrene-butadiene rubber accounts for 80-90 wt%.
Optionally, the weight ratio of the attapulgite to the graphene oxide is 6: (8-12).
Optionally, the particle size of the attapulgite is 0.2-1 μm.
In a second aspect, the present invention provides a method for preparing the above conductive composite adhesive, comprising the steps of:
S1, grinding polythiophene into powder, mixing and melting the powder with styrene-butadiene rubber according to the formula amount, adding attapulgite according to the formula amount, and performing extrusion granulation to obtain mixed particles;
s2, adding graphene oxide into the mixed particles, and mixing to obtain the conductive composite adhesive.
Optionally, the extrusion temperature in the step S1 is 100-120 ℃.
Optionally, the mixing temperature in the step S2 is 110-130 ℃.
In a third aspect, the invention provides an electrode sheet, wherein the conductive composite binder and the active material are mixed according to the weight ratio (5-20): (80-95) mixing and extruding to obtain a pasty mixture; and rolling the pasty mixture and a current collector to obtain the electrode plate.
Optionally, the extrusion temperature is 180-220 ℃.
Optionally, the rolling temperature is 150-180 ℃.
In a fourth aspect, the invention provides an application of the electrode slice in a positive electrode and/or a negative electrode in a lithium battery.
In summary, the technical scheme of the invention has the following beneficial effects:
1. According to the technical scheme, the styrene-butadiene rubber, the polythiophene and the attapulgite are mixed in a melting way, and the peel strength of the electrode plate is improved by utilizing the combination of the toughness of the styrene-butadiene rubber and the rigidity of the polythiophene;
2. The benzene ring structure in the styrene-butadiene rubber and the thiophene ring structure in the polythiophene can form pi electron movement chains, so that electrons can move conveniently, holes exist in polythiophene molecules, the movement of electrons is further promoted, the movement rate of electrons in the styrene-butadiene rubber and the polythiophene molecules is improved, and the resistance of an electrode plate is reduced;
3. The bar-shaped structure of the attapulgite can form a plurality of gap channels in the mixture of the styrene-butadiene rubber and the polythiophene, and the porous structure of the attapulgite forms an electron/lithium ion movement channel, and graphene oxide is added into the mixture of the styrene-butadiene rubber, the polythiophene and the attapulgite and mixed, so that the flaky graphene oxide is uniformly dispersed and partially embedded into holes of the attapulgite in the continuous rolling process, and electrons/lithium ions are led to enter the movement channel of the attapulgite, so that the electrons/lithium ions can move in the mixture of the styrene-butadiene rubber and the polythiophene; the partial graphene oxide embedded into the holes of the attapulgite can accelerate the movement rate of electrons/lithium ions in the movement channel, so that the interference of the binder on the rapid movement of the lithium ions in the positive and negative active substances is reduced; especially in the interface between the binder and the active material, the interface between the binder and the current collector and the interface between the active material and the current collector, the attapulgite structure of the embedded part of graphene oxide in the conductive composite binder can effectively reduce the resistance of lithium ions moving at the interface;
4. The conductive composite adhesive can be suitable for positive electrode plates and negative electrode plates, and can meet the movement and deintercalation of electrons/lithium ions in positive electrode active materials/negative electrode active materials.
Drawings
Fig. 1 is a scanning electron microscope image of graphene oxide of the present invention.
Detailed Description
The invention is described in further detail below with reference to the drawings and examples.
The invention designs a conductive composite adhesive which is prepared from the following components in parts by weight:
100 parts of a mixture of styrene-butadiene rubber and polythiophene;
0.2-0.8 parts of attapulgite;
0.4-1 part of graphene oxide;
wherein, in the mixture of the styrene-butadiene rubber and the polythiophene, the styrene-butadiene rubber accounts for 80-90 wt%.
In the prior art, the addition amount of the binder is increased to reduce the movement rate of electrons and influence the intercalation/deintercalation of lithium ions into/from active substances due to poor conductive performance of the binder; the interface movement resistance of lithium ions is very high, and especially when the binder is between the current collector and the active material, the interface resistance between the current collector and the active material is further increased; however, if the amount of the binder is reduced, the effect of bonding the active material to the foil body is poor, and the powder is easily removed after a plurality of cycles.
Therefore, the inventor researches out a conductive composite adhesive with better conductive performance, through replacing the adhesive with styrene-butadiene rubber and polythiophene with conductive performance, through melt mixing of the styrene-butadiene rubber, the polythiophene and the attapulgite, the peel strength of the electrode slice is improved by utilizing the combination of the toughness of the styrene-butadiene rubber and the rigidity of the polythiophene.
The benzene ring structure in the styrene-butadiene rubber and the thiophene ring structure in the polythiophene can form pi electron movement chains, so that electrons can move conveniently, holes exist in polythiophene molecules, the movement of electrons is further promoted, the movement rate of electrons in the styrene-butadiene rubber and the polythiophene molecules is improved, and the resistance of the electrode plate is reduced.
The bar-shaped structure of the attapulgite can form a plurality of gap channels in the mixture of the styrene-butadiene rubber and the polythiophene, and the porous structure of the attapulgite forms an electron/lithium ion movement channel, and graphene oxide is added into the mixture of the styrene-butadiene rubber, the polythiophene and the attapulgite and mixed, so that the flaky graphene oxide is uniformly dispersed and partially embedded into holes of the attapulgite in the continuous rolling process, and electrons/lithium ions are led to enter the movement channel of the attapulgite, so that the electrons/lithium ions can move in the mixture of the styrene-butadiene rubber and the polythiophene; the partial graphene oxide embedded into the holes of the attapulgite can accelerate the movement rate of electrons/lithium ions in the movement channel, so that the interference of the binder on the rapid movement of the lithium ions in the positive and negative active substances is reduced; especially, in the interface between the binder and the active material, the interface between the binder and the current collector and the interface between the active material and the current collector, the attapulgite structure of the embedded part of graphene oxide in the conductive composite binder can effectively reduce the resistance of lithium ions moving at the interface.
The invention also designs a preparation method of the conductive composite adhesive, which comprises the following steps:
S1, grinding polythiophene into powder, mixing and melting the powder with styrene-butadiene rubber according to the formula amount, adding attapulgite according to the formula amount, and performing extrusion granulation to obtain mixed particles;
s2, adding graphene oxide into the mixed particles, and mixing to obtain the conductive composite adhesive.
Firstly, the polythiophene is melted and mixed in the styrene-butadiene rubber, the attapulgite is uniformly dispersed in the mixture, a plurality of rod-shaped gap channels are formed between the mixture of the styrene-butadiene rubber and the polythiophene, and the porous structure of the attapulgite forms an electron/lithium ion movement channel.
And adding the obtained mixed particles into graphene oxide for mixing, so that the attapulgite can adsorb the graphene oxide, and partially embedding the flaky graphene oxide into the porous structure of the attapulgite by continuously high-temperature rolling.
The invention also designs an electrode slice, which comprises the conductive composite binder and active substances according to the weight ratio of (5-20): (80-95) mixing and extruding to obtain a pasty mixture; and rolling the pasty mixture and a current collector to obtain the electrode plate.
The inventor adopts the conductive composite adhesive according to the weight ratio of the conductive composite adhesive to the active material (5-20): (80-95) mixing and extruding to obtain paste, and rolling with a current collector to obtain the positive electrode/negative electrode plate. The prepared positive electrode/negative electrode plate has high peeling strength and smaller resistance.
The invention also designs application of the electrode slice in the anode and/or the cathode of the lithium battery. The first charge specific capacity of the lithium battery is higher, the first discharge specific capacity is higher, and the charge and discharge efficiency of the lithium battery is higher; and the retention rate is high after 50 cycles.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
In the examples of the present invention which follow, the main components referred to are, unless otherwise specified, commercially available products.
Styrene-butadiene rubber: purchased from Shanghai Micin Biochemical technologies Co., ltd.
Polythiophene: purchased from Jin Jinle (Hunan) chemical Co., ltd.
Attapulgite: the grain diameter is 0.2 μm to 1 μm.
Graphene oxide: the diameter is 0.01-15 mu m, the thickness is 0.55-nm-3.85 nm, the layer number is less than 10 and more than 99%wt; purchased from Shenzhen Tuling evolution technology Co., ltd; as shown in fig. 1, a scanning electron microscope image of graphene oxide used in the present invention is shown.
The current collector in the following examples of the present invention is exemplified by aluminum foil.
The active materials for preparing the negative electrode plate can adopt hard carbon, graphite, mesophase carbon microspheres, soft carbon and the like; graphite is used for example.
The active materials for preparing the negative electrode plate can adopt lithium cobaltate, lithium manganate, lithium iron phosphate, ternary materials, lithium nickelate and the like; lithium iron phosphate is exemplary employed.
Examples 1-4 and comparative examples 1-4 were used to prepare a conductive composite adhesive, wherein the formulations of each example and each comparative example are shown in table 1; the preparation method of the conductive composite adhesive in the embodiments 1-4 comprises the following steps: grinding polythiophene into powder, and extruding and granulating with styrene-butadiene rubber and attapulgite at 100-120 ℃ to obtain mixed particles; adding graphene oxide into the mixed particles, and mixing by an internal mixer, wherein the mixing temperature is 110-130 ℃, the mixing time is 15-25 minutes, and the mixing rotating speed is 24-28 r/min; and obtaining the conductive composite adhesive.
TABLE 1
Application examples 1 to 8 the conductive composite binders prepared in examples 1 to 5 and comparative examples 1 to 3 were used to prepare electrode sheets, respectively, as follows.
Positive electrode sheet: the conductive composite binder prepared in examples 1 to 5 and comparative examples 1 to 3 was mixed with a positive electrode active material in a weight ratio of 8:92, mixing and extruding, wherein the extruding temperature is 180-220 ℃, so as to obtain a pasty mixture; and rolling the pasty mixture and a current collector (aluminum foil), wherein the rolling temperature is 150-180 ℃, and the thickness of a rolled film layer is 100 mu m, so that the positive electrode plate is obtained.
Negative electrode sheet: the conductive composite binder prepared in examples 1 to 5 and comparative examples 1 to 3 was mixed with a negative electrode active material in a weight ratio of 5:95, mixing and extruding, wherein the extruding temperature is 180-220 ℃, so as to obtain a pasty mixture; and rolling the pasty mixture and a current collector (copper foil), wherein the rolling temperature is 150-180 ℃, and the thickness of a rolled film layer is 100 mu m, so that the positive electrode plate is obtained.
The peel strength test was performed on the positive electrode sheet/negative electrode sheet according to GB/T2792-1998 standard.
And (3) carrying out resistance test on the positive electrode plate/negative electrode plate by adopting a four-probe method, wherein the test method is as follows.
The pole piece is cut into square size of 4cm multiplied by 8cm, then the pole piece is placed under two probes, the two probes are connected with a resistance meter through two pole posts, the handle probe of the rotary testing device is pressed by stable pressure, the pressure is controlled by the pressure meter, and after the pressure requirement is met, the resistance data of the resistance meter is read, and the data is the relative value of the resistance of the pole piece.
The test results are shown in Table 2.
TABLE 2
As can be seen from application examples 1-5 and Table 2, the peel strength of the positive electrode sheet prepared by the conductive composite adhesive of examples 1-5 can reach more than 180N/m, the sheet resistance is not more than 120mΩ (compared with the sheet resistance which can be obtained by 4cm×8cm, the sheet internal resistance is not more than 5mΩ/cm 2). The peel strength of the negative electrode plate prepared by the conductive composite adhesive can reach more than 40N/m.
As can be seen from comparative examples 3 (example 3) and 6 (comparative example 1), the conductive composite adhesive of the present invention has significantly reduced peel strength of the positive/negative electrode sheets without adding polythiophene; the styrene-butadiene rubber has good elasticity, so that the part bonded with the current collector is easy to fall off locally when a peeling strength experiment is carried out, and then the bonding between other parts and the current collector is influenced, so that the peeling strength is reduced; after a small amount of polythiophene is added, the rigidity of the styrene-butadiene rubber can be improved, and the part bonded with the current collector forms a whole, so that the peeling strength is improved.
And the internal resistance of the positive electrode sheet of application example 6 is increased relative to application example 3; this is because the polythiophene molecule contains thiophene rings, and pi electron chains are formed by conjugation between the thiophene rings, so that the conductivity can be improved, and holes exist in the polythiophene molecule, so that the charge movement can be further promoted. Therefore, after a small amount of polythiophene is added in application example 3, the internal resistance of the prepared positive electrode plate is obviously reduced compared with application example 6.
As is clear from comparative examples 3 (example 3) and 7 (comparative example 2), if polythiophene is used alone as a binder for an active material and a current collector, the binding effect is greatly reduced. The polythiophene has higher rigidity than styrene-butadiene rubber, and has higher strength but poorer bonding degree with a current collector, so that the peel strength of the positive electrode/negative electrode piece which singly adopts the polythiophene as a bonding agent is lower; and because the molecular gap of the polythiophene is smaller, lithium ions are not easy to move, and the resistance of the positive electrode plate is increased under the condition of more added polythiophene.
As is clear from comparative examples 3 (example 3) and 8 (comparative example 3), the peel strength of the positive electrode/negative electrode sheet slightly decreased without adding attapulgite, but the resistance of the positive electrode sheet increased more; the method is mainly characterized in that a certain attapulgite is added, a plurality of channels can be supported in the positive electrode plate by utilizing rod-shaped fibers of the attapulgite, and the lithium ions can move conveniently through the channels which are rich in the attapulgite and are wider than the lithium ions, so that the lithium ions can be separated and intercalated conveniently; therefore, the resistance of the positive pole piece can be effectively reduced; and graphene oxide is embedded into the channel of the attapulgite, so that the movement rate of electrons and lithium ions is improved.
As can be seen from examples 1 to 5 and table 2, the peel strength of the positive/negative electrode sheets corresponding to examples 1 to 3 and example 5 is high and the resistance of the positive electrode sheet is low. The inventors therefore made the following examples for further analysis.
Examples 6 to 8 are used for preparing a conductive composite adhesive, and are different from example 1 in the addition amount of graphene; specifically, the results are shown in Table 3.
TABLE 3 Table 3
Application examples 9 to 11 positive/negative electrode sheets were prepared by using the conductive composite binders prepared in examples 6 to 8, respectively, in the same manner as described above, and performance test was performed, and the results are shown in table 4.
TABLE 4 Table 4
As can be seen from comparison of application examples 1 and 9-11, in the case that the content of graphene oxide in the conductive composite adhesive in the embodiment 1 of the present invention is gradually increased, the peel strength of the prepared positive/negative electrode sheet is reduced, the resistance is increased, and the performance is reduced; therefore, when the weight ratio of the attapulgite to the graphene oxide in the conductive composite adhesive is lower than 1:2, the performance of the prepared positive/negative electrode plate is reduced.
Examples 9-12 were used to prepare a conductive composite binder, differing from example 2 in the amount of graphene added; specifically, the results are shown in Table 5.
TABLE 5
Application examples 12 to 15 positive/negative electrode sheets were prepared by using the conductive composite binders prepared in examples 9 to 12, respectively, in the same manner as described above, and performance test was performed, and the results are shown in table 6.
TABLE 6
As can be seen from comparison of application examples 2 and application examples 12-15, under the condition that the content of graphene oxide in the conductive composite adhesive in the embodiment 2 of the invention is gradually increased, the peel strength of the prepared positive electrode/negative electrode plate is firstly increased and then decreased, the resistance is firstly decreased and then increased, and the comprehensive performance is firstly increased and then decreased; therefore, when the weight ratio of the attapulgite to the graphene oxide in the conductive composite adhesive is 4: in the interval (6-10), the performance of the prepared positive electrode/negative electrode plate is firstly increased and then decreased; and when the weight ratio of the attapulgite to the graphene oxide is 4: and (6) in the interval (6-8), the prepared positive electrode/negative electrode plate has better performance.
Examples 13 to 14 are used for preparing a conductive composite adhesive, and are different from example 3 in the addition amount of graphene; specifically, the results are shown in Table 7.
TABLE 7
Application examples 16 to 17 the positive/negative electrode sheets were prepared by using the conductive composite binders prepared in examples 13 to 14, respectively, in the same manner as described above, and performance test was performed, and the results are shown in table 8.
TABLE 8
As can be seen from comparison of application examples 3 and application examples 16 to 17, in the case that the addition amount of graphene oxide in the conductive composite adhesive in the embodiment 3 of the present invention is changed, the weight ratio of attapulgite to graphene oxide in the conductive composite adhesive is 6: in the interval (6-10), the peel strength of the prepared positive electrode/negative electrode plate gradually decreases, the resistance of the positive electrode plate is firstly decreased and then increased, and the comprehensive performance is firstly increased and then decreased; therefore, when the weight ratio of the attapulgite to the graphene oxide in the conductive composite adhesive is 4: (6-10), wherein the comprehensive performance of the prepared positive electrode/negative electrode plate is firstly increased and then decreased; and when the weight ratio of the attapulgite to the graphene oxide is 6: and (8) in the interval (8-10), the prepared positive electrode/negative electrode plate has better performance.
Example 15 was used to prepare a conductive composite binder, differing from example 4 in the amount of graphene added; as shown in table 9.
TABLE 9
Application example 18 the positive/negative electrode sheets were prepared by using the conductive composite binders prepared in examples 15 to 16, respectively, in the same manner as described above, and performance test was performed, and the results are shown in table 10.
Table 10
As is clear from the comparison between application example 4 and application example 18, when the amount of graphene oxide added to the conductive composite adhesive in example 4 of the present invention was reduced, the peel strength of the prepared positive electrode/negative electrode sheet was improved, but the resistance of the positive electrode sheet was increased, and the overall performance was reduced.
The peel strength of the positive electrode/negative electrode sheet and the resistance of the positive electrode sheet prepared in comprehensive application examples 9-18 can be known that the weight ratio of the attapulgite to the graphene oxide in the conductive composite adhesive is 4: and (6-12), the prepared positive electrode/negative electrode plate has higher peeling strength, the resistance of the positive electrode plate is intersected, and the comprehensive performance of the positive electrode/negative electrode plate is better.
Performance testing
The positive electrode/negative electrode sheet prepared in application examples 1-5 was prepared by using Celgard2400 as a separator, and 1mol/L LiPF6, ethylene Carbonate (EC), dimethyl carbonate (DMC) and Ethyl Methyl Carbonate (EMC) as electrolyte, wherein the volume ratio of Ethylene Carbonate (EC), dimethyl carbonate (DMC) and Ethyl Methyl Carbonate (EMC) was 1:1:1, a CR2025 button cell was assembled in a glove box filled with argon, and was designated as cell 1 to cell 5, and electrochemical tests were performed on cell 1 to cell 5. Specifically using a LAND battery test system, and performing electrochemical performance test on the button battery at 2V-3.2V and 0.1C multiplying power; the results are shown in Table 11.
TABLE 11
As can be seen from Table 11, the lithium battery assembled by the positive electrode/negative electrode plate prepared by the conductive composite adhesive has a specific capacity of more than 260mAh/g for the first charge, a specific capacity of more than 240mAh/g for the first discharge, a charge and discharge efficiency of more than 91%, and a retention rate of more than 92% for 1C/1C50 cycles.
The above embodiments are not intended to limit the scope of the present invention, so: all equivalent changes in structure, shape and principle of the invention should be covered in the scope of protection of the invention.
Claims (10)
1. The conductive composite adhesive is characterized by being prepared from the following components in parts by weight:
100 parts of a mixture of styrene-butadiene rubber and polythiophene;
0.2-0.8 parts of attapulgite;
0.4-1 part of graphene oxide;
wherein, in the mixture of the styrene-butadiene rubber and the polythiophene, the styrene-butadiene rubber accounts for 80-90 wt%.
2. The conductive composite binder of claim 1 wherein the weight ratio of attapulgite to graphene oxide is 6: (8-12).
3. The conductive composite binder of claim 1, wherein the attapulgite has a particle size of 0.2-1 μm.
4. A method of preparing the conductive composite adhesive of claim 1, comprising the steps of:
S1, grinding polythiophene into powder, mixing and melting the powder with styrene-butadiene rubber according to the formula amount, adding attapulgite according to the formula amount, and performing extrusion granulation to obtain mixed particles;
s2, adding graphene oxide into the mixed particles, and mixing to obtain the conductive composite adhesive.
5. The method according to claim 4, wherein the extrusion temperature in S1 is 100 to 120 ℃.
6. The method according to claim 4, wherein the mixing temperature in S2 is 110 to 130 ℃.
7. An electrode sheet characterized in that the conductive composite binder according to claim 1 and an active material are mixed according to the weight ratio (5-20): (80-95) mixing and extruding to obtain a pasty mixture; and rolling the pasty mixture and a current collector to obtain the electrode plate.
8. The electrode sheet of claim 7, wherein the extrusion temperature is 180-220 ℃.
9. The electrode sheet of claim 7, wherein the rolling temperature is 150-180 ℃.
10. Use of an electrode sheet as claimed in claim 7 in a positive and/or negative electrode in a lithium battery.
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