CN102324493B - There is thick electrode of good electrical chemical property and preparation method thereof - Google Patents
There is thick electrode of good electrical chemical property and preparation method thereof Download PDFInfo
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- CN102324493B CN102324493B CN201110247550.XA CN201110247550A CN102324493B CN 102324493 B CN102324493 B CN 102324493B CN 201110247550 A CN201110247550 A CN 201110247550A CN 102324493 B CN102324493 B CN 102324493B
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Abstract
The invention discloses a kind of thick electrode with good electrical chemical property, it comprises collector and the electrode diaphragm distributed on a current collector containing active material and conductive materials, electrode diaphragm comprises near the internal layer diaphragm of collector and the outer diaphragm away from collector, the thickness of electrode diaphragm is greater than 300 μm, reduce from internal layer diaphragm to the conductivity of outer membrane plate electrode diaphragm, increase from internal layer diaphragm to the porosity of outer membrane plate electrode diaphragm.The conductivity of internal layer diaphragm is comparatively large, the electronics at collector place can be made to enter fast or deviate from internal layer diaphragm.The porosity of outer diaphragm is comparatively large, can absorb more electrolyte, solve the problem of the electrolyte wettability difference that thick electrode brings.In addition, the invention also discloses a kind of preparation method with the thick electrode of good electrical chemical property.
Description
Technical field
The invention belongs to field of lithium ion battery, more particularly, the present invention relates to and a kind of there is thick electrode of good electrical chemical property and preparation method thereof.
Background technology
At present, along with the continuous progress of science and technology, the application of lithium ion battery is also expanded rapidly, extends to from portable mobile apparatus such as initial mobile phone, video cameras the Large Electric equipment that the high-power high-energy such as electric bicycle, electric automobile requires.Therefore, also more and more higher to the requirement of the designing and making technique of lithium ion battery.
The main equipment such as electric bicycle and electric automobile requires that lithium ion battery has high energy density.Consider from the angle of design, the ideal style that can improve energy density is the content increasing active material, improves the thickness of electrode plates.But in actual application, the thickness of electrode plates can because cannot significantly increase by the restriction of battery penalty.Under the prerequisite ensureing performance of lithium ion battery, how to increase the thickness of electrode plates as far as possible, become the major issue affecting lithium ion battery applications prospect.
Such as, Chinese invention patent application CN200910261533.4 discloses a kind of electrode for rechargeable lithium ion batteries, by the design that conductivity in electrode is different, pole piece can be avoided to occur that crackle causes the problem of chemical property difference.But the design of this application for a patent for invention only considers the impact that conductive materials produces pole piece, have ignored the other problems that thick electrode brings because thickness is excessive.The lithium ion battery of thick electrode is adopted to be generally used for the Large Electric equipment of high current charge-discharge, therefore must solve the problem that pole piece internal concentration polarization is large, high rate performance is poor under large current density electricity condition, the different designs only by conductivity in pole piece also cannot make thick electrode have good chemical property.
Chinese invention patent application CN200580027135.6 also discloses a kind of electrode structure and manufacture method thereof, and the feature of this electrode structure is: have from interior (near collector) to the porosity heterogeneous of (away from collector) direction reduction.This electrode structure can improve the utilance of electrode active material, to improve capacity and power.But, in the charge and discharge cycles process of battery, the transmission of lithium ion in electrode plates is from outer (away from collector) to interior (near collector), if adopt from interior (near collector) to the structural design of porosity heterogeneous of (away from collector) direction reduction, after charge and discharge cycles carries out a period of time, the pole piece skin of small porosity cannot retain the used for electrolyte in the transmission of lithium ion of abundance, therefore can reduce the lasting performance of the outer chemical property of pole piece.
In view of this, necessaryly provide a kind of there is thick electrode of good electrical chemical property and preparation method thereof.
Summary of the invention
In order to give full play to the chemical property of thick electrode, when designing, the impact (wettability as electrolyte poor, pole piece big current high rate performance poor and cycle performance poor) of pole piece thickness on battery performance will be considered on the one hand comprehensively, also to consider that the preparation process of the thick electrode with good electrical chemical property easily realizes on the other hand, be consistent with existing technological level as far as possible.
Goal of the invention of the present invention is: provide a kind of and have thick electrode of good electrical chemical property and preparation method thereof.
In order to realize foregoing invention object, the invention provides a kind of thick electrode with good electrical chemical property, it comprises collector and the electrode diaphragm distributed on a current collector containing active material and conductive materials, electrode diaphragm comprises near the internal layer diaphragm of collector and the outer diaphragm away from collector, the thickness of electrode diaphragm is greater than 300 μm, increases from internal layer diaphragm to the porosity of outer membrane plate electrode diaphragm.
One as thick electrode of the present invention is improved, and the porosity of described internal layer diaphragm is 5% ~ 10%, and the porosity of outer diaphragm is 15% ~ 30%.
One as thick electrode of the present invention is improved, and the thickness of described electrode diaphragm is 300 ~ 3000 μm.
One as thick electrode of the present invention is improved, and the ion-transfer resistance of described internal layer diaphragm is less than the ion-transfer resistance of outer diaphragm.
One as thick electrode of the present invention is improved, and described electrode diaphragm is also containing the electrolyte transmitter for transmitting or store electrolyte.
One as thick electrode of the present invention is improved, and described electrolyte transmitter is carbon nano-tube and/or carbon fiber.
One as thick electrode of the present invention is improved, and the thickness of described internal layer diaphragm is the 1%-90% of thick electrode thickness, and the thickness of outer diaphragm is the 10%-99% of thick electrode thickness.
One as thick electrode of the present invention is improved, and described thick electrode is positive pole, and described electrode diaphragm is also containing metal oxide, and metal oxide is coated on the surface of described active material particle.
One as thick electrode of the present invention is improved, and in described internal layer diaphragm, the mass content of conductive materials is 2% ~ 10%, and in outer diaphragm, the mass content of conductive materials is 0% ~ 5%.
One as thick electrode of the present invention is improved, and the conductivity of electrode diaphragm described in from internal layer diaphragm to outer diaphragm reduces.
One as thick electrode of the present invention is improved, and described internal layer diaphragm is identical with the conductive materials of outer diaphragm, and in internal layer diaphragm, the content of conductive materials is greater than the content of conductive materials in outer diaphragm.
In order to realize foregoing invention object, present invention also offers a kind of preparation method with the thick electrode of good electrical chemical property, it comprises the following steps:
A) collector is provided;
B) electrode diaphragm composition is provided, containing active material and conductive materials in electrode diaphragm composition;
C) apply one or more layers step b on a current collector) electrode diaphragm composition, through pore-creating and/or oven dry, form internal layer diaphragm, and
D) in step c) obtained internal layer diaphragm applies one or more layers step b) electrode diaphragm composition, through pore-creating and/or oven dry, form outer diaphragm;
Wherein, described steps d) in the porosity of outer diaphragm be greater than step c) in the porosity of internal layer diaphragm.
One as the preparation method of thick electrode of the present invention is improved, described step c) and described steps d) in pore-creating be cold pressing treatment, described step c) in the pressure of cold pressing treatment be greater than described steps d) in the pressure of cold pressing treatment.
One as the preparation method of thick electrode of the present invention is improved, described step b) electrode diaphragm composition in also containing pore creating material, described step c) and steps d) in pore-creating be heating, drying process.
One as the preparation method of thick electrode of the present invention is improved, and described pore creating material is one or more in benzoic acid, carbonic hydroammonium, Celogen Az.
One as the preparation method of thick electrode of the present invention is improved, described step b) electrode diaphragm composition in also containing metal oxide, metal oxide is selected from one or more in alundum (Al2O3), magnesium oxide, zinc oxide, zirconia.
One as the preparation method of thick electrode of the present invention is improved, and described electrode diaphragm composition is also containing the electrolyte transmitter for transmitting or store electrolyte.
One as the preparation method of thick electrode of the present invention is improved, steps d) in the conductivity of outer diaphragm be less than step c) in the conductivity of internal layer diaphragm.
One as the preparation method of thick electrode of the present invention is improved, and described internal layer diaphragm is identical with the conductive materials in outer diaphragm, and in internal layer diaphragm, the content of conductive materials is greater than the content of conductive materials in outer diaphragm.
Relative to prior art, the present invention at least has the following advantages: the porosity of the outer diaphragm of thick electrode is larger, make can absorb more electrolyte in outer diaphragm, solve the problem of the electrolyte wettability difference that thick electrode brings, top layer porosity shows that greatly top layer active material is few, lithium ion like this for same current unit time endosexine consumption is just few, is more conducive to internal layer active material and plays a role; Secondly, porosity large lithium ion in top layer arrives internal layer more ion channel, has slackened the capacitance loss that concentration polarization brings like this; The conductivity of internal layer diaphragm is comparatively large, the electronics at collector place can be made to enter fast or deviate from internal layer diaphragm, solving the problem of the pole piece high rate performance difference that thick electrode brings; Outer diaphragm has larger ion-transfer resistance; the ion that outer diaphragm active material particle obtains or departs from can be reduced; the corresponding ion adding internal layer diaphragm active material particle and obtain or depart from; solve the concentration polarization problem that the thick electrode that causes because of thickness increase occurs in charge and discharge process, improve the high rate performance of pole piece.Therefore, thick electrode of the present invention not only has good chemical property, and can significantly improve the energy density of battery.
Accompanying drawing explanation
Below in conjunction with the drawings and specific embodiments, the present invention and Advantageous Effects thereof are described in detail.
Fig. 1 is the structural representation that the present invention has an execution mode of the thick electrode of good electrical chemical property.
Embodiment
Refer to shown in Fig. 1, the thick pole piece that the present invention has a good electrical chemical property refers to the pole piece that thickness is greater than 300 μm (preferred thickness is 300 ~ 3000 μm), and it comprises collector 10 and the electrode diaphragm be distributed in containing active material 204,304 and conductive materials 202,302 on collector 10.Electrode diaphragm comprises near the internal layer diaphragm 20 of collector 10 and the outer diaphragm 30 away from collector 10, the conductivity of electrode diaphragm reduces along from internal layer diaphragm 20 to outer diaphragm 30 direction, and the porosity of electrode diaphragm increases along from internal layer diaphragm 20 to outer diaphragm 30 direction.
The thickness range of internal layer diaphragm and outer diaphragm can change with the thickness of the thick pole piece of the present invention.Preferably, the thickness of internal layer diaphragm is the 1%-90% of thick electrode thickness, and the thickness of outer diaphragm is the 10%-99% of thick electrode thickness.
Conductivity is relevant with content with the kind of conductive materials 202,302.In the present invention, the conductive materials 202 of internal layer diaphragm 20 can be different types of conductive materials with the conductive materials 302 of outer diaphragm 30, also can be that kind is identical but the conductive materials that content is different, as long as can ensure that the conductivity of internal layer diaphragm 20 is greater than the conductivity of outer diaphragm 30.Such as, according to an embodiment of the invention, conductive materials 202 in internal layer diaphragm 20 is identical conductive materials with the conductive materials 302 in outer diaphragm 30, but the content of the conductive materials 202 in internal layer diaphragm 20 is greater than the content of the conductive materials 302 in outer diaphragm 30.Such as, the conductive materials in internal layer diaphragm 20 and outer diaphragm 30 is conductive carbon, carbon nano-tube or carbon fiber, and the mass content of the conductive materials 202 in internal layer diaphragm 20 is 2% ~ 10%, and the mass content of the conductive materials 302 of outer diaphragm 30 is 0% ~ 5%.
The factors such as the pressure in the proportioning of porosity and the slurry that pole piece composition is formed, composition, content and cold pressure procedure are relevant.In embodiments of the present invention, the control mode of porosity is not particularly limited, as long as can ensure that the porosity of electrode diaphragm increases along from internal layer diaphragm 20 to outer diaphragm 30 direction.Such as, according to an embodiment of the invention, the porosity of internal layer diaphragm 20 is 5% ~ 10%, and the porosity of outer diaphragm 30 is 15% ~ 30%.
Have in the present invention in the preparation process of the thick electrode of good electrical chemical property, only can change a kind of factor affecting porosity in internal layer diaphragm 20 and outer diaphragm 30, and keep ceteris paribus.Such as, according to an embodiment of the invention, the pressure of internal layer diaphragm 20 in cold pressing treatment is greater than the pressure of outer diaphragm 30 when cold pressing treatment, and the porosity that can control outer diaphragm 30 is greater than the porosity of internal layer diaphragm 20.According to another implementation of the invention, pore creating material (as benzoic acid, carbonic hydroammonium or Celogen Az) can be used when forming outer diaphragm 30, ensureing that the porosity of outer diaphragm 30 is greater than the porosity of internal layer diaphragm 20.
The thick pole piece that the present invention has a good electrical chemical property can also comprise the electrolyte transmitter for transmitting or store electrolyte, and electrolyte transmitter has tubulose or filamentary structure, and is uniformly distributed in pole piece.Preferably, adopt carbon nano-tube or carbon fiber as electrolyte transmitter.Electrolyte transmitter effectively can transmit electrolyte, avoids pole piece to increase the problem of the partial electrolysis immersion lubricant nature difference of generation due to thickness.In addition, unnecessary electrolyte can also be carried out local storage by the tubular conduit of carbon nano-tube, is conducive to thick electrode in cyclic process, supplements the electrolyte consumed, maintain good cycle performance.
The present invention has in the electrode diaphragm of the thick electrode of good electrical chemical property can also contain metal oxide, active material particle 204 in internal layer diaphragm 20 is all coated with metal oxide with the active material particle 304 in outer diaphragm 30, as alundum (Al2O3), magnesium oxide, zinc oxide, zirconia or its combination.In charge and discharge process, " film " that ion can be formed by active material particle 204,304 coated metal oxides under electric field action, thus embed or deviate from active material particle 204,304, the inhibition be subject to through ion time " film " is ion-transfer resistance.For the discharge process of cobalt acid lithium system lithium ion battery, after the cobalt acid lithium particles coat of the outer diaphragm of anode pole piece has metal oxide alundum (Al2O3), there is higher ion-transfer resistance, lithium ion cobalt acid more difficult to get access lithium particle is made in discharge process, thus correspondingly add the quantity that lithium ion enters internal layer diaphragm, reduce the concentration polarization that the inner lithium ion of anode pole piece produces, improve the high rate performance of lithium ion battery.
Describe the present invention in detail below in conjunction with embodiment, but be understandable that, the present invention is not limited to the embodiment provided.
Embodiment
embodiment 1
The making of positive plate: by positive active material cobalt acid lithium (LiCoO
2), conductive agent carbon black, binding agent polyvinylidene fluoride (PVDF) and solvent N-methyl pyrilidone (NMP) by weight 92:3:5:80 Homogeneous phase mixing, obtain internal layer slurry to be applied; Internal layer slurry is evenly coated in the aluminum foil current collector of thick 14 microns, then dries at 110 DEG C, after first time cold pressing treatment, namely obtain the internal layer diaphragm that coating layer thickness is about 150 microns.
The positive active material cobalt acid lithium (LiCoO that mass content is the alundum (Al2O3) of 0.6% will be coated with
2), the outer slurry that obtains by weight 94:1.5:4.5:80 Homogeneous phase mixing of carbon nano-tube, polyvinylidene fluoride (PVDF) and solvent N-methyl pyrilidone (NMP) evenly applies on the internal layer diaphragm that is coated in and dried, then dry at 110 DEG C, after second time cold pressing treatment, obtain the outer diaphragm of coating layer thickness about 150 microns.The so obtained positive plate with double-deck cathode film chip architecture, positive plate integral thickness is about 310 microns.Wherein, the pressure of cold pressing treatment is greater than the pressure of second time cold pressing treatment for the first time, ensure that the porosity of internal layer diaphragm is less than the porosity of outer diaphragm.
The making of negative plate: by negative electrode active material Delanium, conductive agent carbon black, bonding agent carboxymethyl cellulose (CMC) and butadiene-styrene rubber (SBR) and aqueous solvent 93:2:2:3:100 Homogeneous phase mixing by weight, obtain cathode size to be applied; Cathode size is evenly coated in the copper foil current collector of thick 9 microns, coating layer thickness about 300 microns, then dries at 100 DEG C, obtained negative plate.
The making of lithium ion battery: by according to obtained positive plate, negative plate and the PP/PE/PP barrier film of previous process by winding or stackedly make battery, battery is placed in battery case and injects electrolyte, obtained lithium ion battery A1.Wherein, electrolyte take concentration as the lithium hexafluoro phosphate (LiPF of 1mol/l
6) be lithium salts, with the mixture of ethylene carbonate (EC), Merlon (PC) and dimethyl carbonate (DMC) for solvent, the weight ratio of EC, PC, DMC is 1:1:1.
embodiment 2
The making of positive plate: by positive active material cobalt acid lithium (LiCoO
2), conductive agent carbon black, binding agent polyvinylidene fluoride (PVDF) and solvent N-methyl pyrilidone (NMP) by weight 92:3:5:80 Homogeneous phase mixing, obtain internal layer slurry to be applied; Internal layer slurry is evenly coated in the aluminum foil current collector of thick 14 microns, coating layer thickness about 150 microns, then dries at 110 DEG C, obtain internal layer diaphragm.
Be the positive active material cobalt acid lithium (LiCoO of the alundum (Al2O3) of 0.6% by coated mass content
2), the outer slurry that obtains by weight 92:1.5:1.5:5:80 Homogeneous phase mixing of carbon nano-tube, benzoic acid, polyvinylidene fluoride (PVDF) and solvent N-methyl pyrilidone (NMP) evenly applies on the internal layer diaphragm that is coated in and dried, coating layer thickness about 150 microns, then dry at 110 DEG C, obtain outer diaphragm, the so obtained positive plate with double-deck diaphragm, the positive plate after colding pressing toasts 5 hours under 125 DEG C of conditions.After the benzoic acid in skin is evaporated completely, the porosity namely obtaining internal layer diaphragm is less than the positive plate of the porosity of outer diaphragm, and positive plate integral thickness is about 300 microns.
The making of negative plate: by negative electrode active material Delanium, conductive agent carbon black, bonding agent carboxymethyl cellulose (CMC) and butadiene-styrene rubber (SBR) and aqueous solvent 93:2:2:3:100 Homogeneous phase mixing by weight, obtain cathode size to be applied; Cathode size is evenly coated in the copper foil current collector of thick 9 microns, coating layer thickness about 300 microns, then dries at 100 DEG C, obtained negative plate.
The making of lithium ion battery: by according to obtained positive plate, negative plate and the PP/PE/PP barrier film of previous process by winding or stackedly make battery, battery is placed in battery case and injects electrolyte, obtained lithium ion battery A2.Wherein, electrolyte take concentration as the lithium hexafluoro phosphate (LiPF of 1mol/l
6) be lithium salts, with the mixture of ethylene carbonate (EC), Merlon (PC) and dimethyl carbonate (DMC) for solvent, the mass ratio of EC, PC, DMC is 1:1:1.
embodiment 3
The making of positive plate: by positive active material cobalt acid lithium (LiCoO
2), conductive agent carbon black, binding agent polyvinylidene fluoride (PVDF) and solvent N-methyl pyrilidone (NMP) by weight 90:3:7:80 Homogeneous phase mixing, obtain internal layer slurry to be applied; Internal layer slurry is evenly coated in the aluminum foil current collector of thick 14 microns, coating layer thickness about 250 microns, then dries at 110 DEG C, obtain internal layer diaphragm.
Be the positive active material cobalt acid lithium (LiCoO of the alundum (Al2O3) of 0.6% by coated mass content
2), the outer slurry that obtains by weight 90:1.5:1.5:7:80 Homogeneous phase mixing of carbon nano-tube, benzoic acid, polyvinylidene fluoride (PVDF) and solvent N-methyl pyrilidone (NMP) evenly applies on the internal layer diaphragm that is coated in and dried, coating layer thickness about 300 microns, then dry at 110 DEG C, obtain outer diaphragm, the so obtained positive plate with double-deck diaphragm, then the positive plate after colding pressing toasts 5 hours under 125 DEG C of conditions.After the benzoic acid in outer diaphragm is evaporated completely, the porosity namely obtaining internal layer diaphragm is less than the positive plate of the porosity of outer diaphragm, and positive plate integral thickness is about 550 microns.
The making of negative plate: by negative electrode active material Delanium, conductive agent carbon black, bonding agent carboxymethyl cellulose (CMC) and butadiene-styrene rubber (SBR) and aqueous solvent 93:2:2:3:100 Homogeneous phase mixing by weight, obtain cathode size to be applied; Cathode size is evenly coated in the copper foil current collector of thick 9 microns, coating layer thickness about 300 microns, then dries at 100 DEG C, obtained negative plate.
The making of lithium ion battery: by according to obtained positive plate, negative plate and the PP/PE/PP barrier film of previous process by winding or stackedly make battery, battery is placed in battery case and injects electrolyte, obtained lithium ion battery A3.Wherein, electrolyte take concentration as the lithium hexafluoro phosphate (LiPF of 1mol/l
6) be lithium salts, with the mixture of ethylene carbonate (EC), Merlon (PC) and dimethyl carbonate (DMC) for solvent, the mass ratio of EC, PC, DMC is 1:1:1.
Embodiment 4
The making of positive plate: by positive active material cobalt acid lithium (LiCoO
2), conductive agent carbon black, benzoic acid, binding agent polyvinylidene fluoride (PVDF) and solvent N-methyl pyrilidone (NMP) by weight 84:2:1:13:80 Homogeneous phase mixing, obtain internal layer slurry to be applied; Internal layer slurry is evenly coated in the aluminum foil current collector of thick 14 microns, coating layer thickness about 400 microns, then dries at 110 DEG C, obtain internal layer diaphragm.
Be the positive active material cobalt acid lithium (LiCoO of the alundum (Al2O3) of 0.6% by coated mass content
2), the outer slurry that obtains by weight 84:1:2:13:80 Homogeneous phase mixing of carbon nano-tube, benzoic acid, polyvinylidene fluoride (PVDF) and solvent N-methyl pyrilidone (NMP) evenly applies on the internal layer diaphragm that is coated in and dried, coating layer thickness about 500 microns, then dry at 110 DEG C, obtain outer diaphragm, the so obtained positive plate with double-deck diaphragm, then the anode pole piece after colding pressing is toasted 5 hours under 125 DEG C of conditions.After the benzoic acid in outer diaphragm is evaporated completely, the porosity namely obtaining internal layer diaphragm is less than the positive plate of the porosity of outer diaphragm, and positive plate integral thickness is about 900 microns.
The making of negative plate: by negative electrode active material Delanium, conductive agent carbon black, bonding agent carboxymethyl cellulose (CMC) and butadiene-styrene rubber (SBR) and aqueous solvent 93:2:2:3:100 Homogeneous phase mixing by weight, obtain cathode size to be applied; Cathode size is evenly coated in the copper foil current collector of thick 9 microns, coating layer thickness about 300 microns, then dries at 100 DEG C, obtained negative plate.
The making of lithium ion battery: by according to obtained positive plate, negative plate and the PP/PE/PP barrier film of previous process by winding or stackedly make battery, battery is placed in battery case and injects electrolyte, obtained lithium ion battery A4.Wherein, electrolyte take concentration as the lithium hexafluoro phosphate (LiPF of 1mol/l
6) be lithium salts, with the mixture of ethylene carbonate (EC), Merlon (PC) and dimethyl carbonate (DMC) for solvent, the mass ratio of EC, PC, DMC is 1:1:1.
Embodiment 5
The making of positive plate: by positive active material cobalt acid lithium (LiCoO
2), conductive agent carbon black, benzoic acid, binding agent polyvinylidene fluoride (PVDF) and solvent N-methyl pyrilidone (NMP) by weight 84:2:1:13:80 Homogeneous phase mixing, obtain internal layer slurry to be applied; Internal layer slurry is evenly coated in the aluminum foil current collector of thick 14 microns, coating layer thickness about 1200 microns, then dries at 110 DEG C, obtain internal layer diaphragm.
Be the positive active material cobalt acid lithium (LiCoO of the alundum (Al2O3) of 0.6% by coated mass content
2), the outer slurry that obtains by weight 84:1:2:13:80 Homogeneous phase mixing of carbon nano-tube, benzoic acid, polyvinylidene fluoride (PVDF) and solvent N-methyl pyrilidone (NMP) evenly applies on the internal layer diaphragm that is coated in and dried, coating layer thickness about 100 microns, then dry at 110 DEG C, obtain outer diaphragm, the so obtained positive plate with double-deck diaphragm, then the positive plate after colding pressing is toasted 5 hours under 125 DEG C of conditions.After the benzoic acid in outer diaphragm is evaporated completely, the porosity namely obtaining internal layer diaphragm is less than the positive plate of the porosity of outer diaphragm, and positive plate integral thickness is about 1300 microns.
The making of negative plate: by negative electrode active material Delanium, conductive agent carbon black, bonding agent carboxymethyl cellulose (CMC) and butadiene-styrene rubber (SBR) and aqueous solvent 93:2:2:3:100 Homogeneous phase mixing by weight, obtain cathode size to be applied; Cathode size is evenly coated in the copper foil current collector of thick 9 microns, coating layer thickness about 300 microns, then dries at 100 DEG C, obtained negative plate.
The making of lithium ion battery: by according to obtained positive plate, negative plate and the PP/PE/PP barrier film of previous process by winding or stackedly make battery, battery is placed in battery case and injects electrolyte, obtained lithium ion battery.Wherein, electrolyte take concentration as the lithium hexafluoro phosphate (LiPF of 1mol/l
6) be lithium salts, with the mixture of ethylene carbonate (EC), Merlon (PC) and dimethyl carbonate (DMC) for solvent, the mass ratio of EC, PC, DMC is 1:1:1.
Embodiment 6
The making of positive plate: by positive active material cobalt acid lithium (LiCoO
2), conductive agent carbon black, benzoic acid, binding agent polyvinylidene fluoride (PVDF) and solvent N-methyl pyrilidone (NMP) by weight 84:2:1:13:80 Homogeneous phase mixing, obtain internal layer slurry to be applied; Internal layer slurry is evenly coated in the aluminum foil current collector of thick 14 microns, coating layer thickness about 1200 microns, then dries at 110 DEG C, obtain internal layer diaphragm.
Be the positive active material cobalt acid lithium (LiCoO of the alundum (Al2O3) of 0.6% by coated mass content
2), the outer slurry that obtains by weight 84:1:2:13:80 Homogeneous phase mixing of carbon nano-tube, benzoic acid, polyvinylidene fluoride (PVDF) and solvent N-methyl pyrilidone (NMP) evenly applies on the internal layer diaphragm that is coated in and dried, coating layer thickness about 1300 microns, then dry at 110 DEG C, obtain outer diaphragm, the so obtained positive plate with double-deck diaphragm, then the positive plate after colding pressing is toasted 5 hours under 125 DEG C of conditions.After the benzoic acid in outer diaphragm is evaporated completely, the porosity namely obtaining internal layer diaphragm is less than the positive plate of the porosity of outer diaphragm, and positive plate integral thickness is about 2500 microns.
The making of negative plate: by negative electrode active material Delanium, conductive agent carbon black, bonding agent carboxymethyl cellulose (CMC) and butadiene-styrene rubber (SBR) and aqueous solvent 93:2:2:3:100 Homogeneous phase mixing by weight, obtain cathode size to be applied; Cathode size is evenly coated in the copper foil current collector of thick 9 microns, coating layer thickness about 600 microns, then dries at 100 DEG C, obtained negative plate.
The making of lithium ion battery: by according to obtained positive plate, negative plate and the PP/PE/PP barrier film of previous process by winding or stackedly make battery, battery is placed in battery case and injects electrolyte, obtained lithium ion battery.Wherein, electrolyte take concentration as the lithium hexafluoro phosphate (LiPF of 1mol/l
6) be lithium salts, with the mixture of ethylene carbonate (EC), Merlon (PC) and dimethyl carbonate (DMC) for solvent, the mass ratio of EC, PC, DMC is 1:1:1.
Comparative example 1
The making of positive plate: by positive active material cobalt acid lithium (LiCoO
2), conductive agent carbon black, binding agent polyvinylidene fluoride (PVDF) and solvent N-methyl pyrilidone (NMP) by weight 92:3:5:80 Homogeneous phase mixing, obtain internal layer slurry to be applied; Internal layer slurry is evenly coated in the aluminum foil current collector of thick 14 microns, then dry at 110 DEG C, after cold pressing treatment, namely obtain the internal layer diaphragm that coating layer thickness is about 300 microns, the pressure of cold pressing treatment used be with in embodiment 1 first time cold pressing treatment pressure be consistent.
The making of negative plate: the manufacturing process of negative plate is identical with the negative plate manufacturing process in embodiment 1.
The making of lithium ion battery: the manufacturing process of lithium ion battery is identical with the manufacturing process of lithium ion battery in embodiment 1.
electrode plates wettability is tested
The wetting property of electrode shows in the absorbability of electrolyte and unit interval uptake.Usual wettability method of testing compares the Different electrodes pole piece of identical weight (, than identical, manufacture craft is mutually equal for prescription quality) to the infiltration rate with amount electrolyte, and it is strong that whose absorbability who first blots; Relatively the Different electrodes pole piece of identical weight is immersed in the absorption memory space of electrolyte to electrolyte, and whose uptake of whose Heavy Weight is strong.The electrode plates that embodiment 1 and comparative example 1 obtain is got identical weight and carries out the test of electrolyte infiltration rate and the test of uptake respectively.Result shows that wettability, particularly uptake that the wettability of the thick pole piece of the present invention is better than the obtained thick electrode pole piece of comparative example 1 have larger lifting.
Meanwhile, adopt the method peeled off to be cut separation by the ectonexine diaphragm in embodiment 1, carry out the infiltrating test of pole piece respectively.Result shows, outer diaphragm faster than internal layer diaphragm for the infiltration rate of electrolyte, illustrates that thick electrode pole piece of the present invention has good wettability, can ensure that battery has good cycle performance in theory.
electrode plates conductivity is tested
The membrane resistance test of the test of the conductivity mainly pole piece of battery, method of testing gets its diaphragm test resistance value under unit are under unit pressure.The conductivity that direct measurement has each tunic sheet in the pole piece of multi-layer diaphragm structure is comparatively difficult.Therefore, the only membrane resistance of electrode plates that obtains respectively of testing example 1, comparative example 1, resistance is respectively: 0.04ohm/m
2, 0.08ohm/m
2.Illustrate that the embodiment of the present invention 1 compares ratio 1 and has lower membrane resistance, there is higher conductivity.
the concentration polarization of electrode plates
With just very routine, adopt the anode pole piece of individual layer in battery discharge procedure, because active material is the same, at the active material away from collector place relatively near negative pole, more easily obtain the lithium ion transmitted from negative pole, but the inner active material near collector place can only obtain the lithium ion that a small amount of negative pole transmits, and along with discharge-rate is larger, this phenomenon is more obvious.It can thus be appreciated that concentration polarization is the principal element affecting battery high rate performance, therefore the present invention improves the raising that the major embodiment of electrode concentration polarization is the battery high rate performance applying electrode of the present invention: good rate capability, then electrode concentration polarization is low.
electrochemical property test
1. gram volume test
Probe temperature is 23 ± 2 DEG C, with 0.5C constant current charge to 4.2 ± 0.01V, then uses constant voltage charge, is 0.05C by electric current; Shelve 10 minutes, then with 0.5C electric discharge, be 3.0V by voltage, record this capacity and as cycle life test in initial capacity; Gram volume computing formula: gram volume=0.5C capacity/positive active material weight.
2. cycle life test
Probe temperature is 23 ± 2 DEG C, with 0.5C constant current charge to 4.2 ± 0.01V, then uses constant voltage charge, is 0.05C by electric current; Shelving 10 minutes, then with 0.5C electric discharge, is 3.0V by voltage; Shelve 10 minutes between discharge and recharge, circulate 500 times, recording capacity calculated capacity conservation rate.Capacity ÷ initial capacity after capability retention=circulation 500 times.
3. multiplying power test
Probe temperature is 23 ± 2 DEG C, with 0.5C constant current charge to 4.2 ± 0.01V, then uses constant voltage charge, is 0.05C by electric current; Shelve 10 minutes, then with 0.2C electric discharge, be 3.0V by voltage, record this capacity and as multiplying power test in initial capacity; Again with 0.5C constant current charge to 4.2 ± 0.01V, then using constant voltage charge, is 0.05C by electric current; Shelve 10 minutes; Then with respectively with 1C electric discharge, be 3.0V by voltage, record this capacity and as the rate capability of 1C.
The each embodiment of table 1 and comparative example 1 obtain the performance test results of battery
As can be seen from Table 1, the lithium ion battery with thick electrode that embodiments of the invention obtain has good chemical property and plays.
It should be noted that, although only for positive plate, the present invention will be described in embodiments of the present invention, it will be appreciated by those skilled in the art that, inventive concept of the present invention is applicable to negative plate too.
The announcement of book and instruction according to the above description, those skilled in the art in the invention can also carry out suitable change and amendment to above-mentioned execution mode.Therefore, the present invention is not limited to embodiment disclosed and described above, also should fall in the protection range of claim of the present invention modifications and changes more of the present invention.In addition, although employ some specific terms in this specification, these terms just for convenience of description, do not form any restriction to the present invention.
Claims (14)
1. one kind has the thick electrode of good electrical chemical property, it comprises collector and the electrode diaphragm distributed on a current collector containing active material and conductive materials, electrode diaphragm comprises near the internal layer diaphragm of collector and the outer diaphragm away from collector, it is characterized in that: the thickness of described electrode diaphragm is greater than 300 μm, and increase from internal layer diaphragm to the porosity of outer membrane plate electrode diaphragm; The ion-transfer resistance of described internal layer diaphragm is less than the ion-transfer resistance of outer diaphragm; The conductivity of electrode diaphragm described in from internal layer diaphragm to outer diaphragm reduces; Described thick electrode is positive pole, and described electrode diaphragm is also containing metal oxide, and metal oxide is coated on the surface of active material particle.
2. thick electrode according to claim 1, is characterized in that: the porosity of described internal layer diaphragm is 5% ~ 10%, and the porosity of outer diaphragm is 15% ~ 30%.
3. thick electrode according to claim 1, is characterized in that: the thickness of described electrode diaphragm is 300 ~ 3000 μm.
4. thick electrode according to claim 1, is characterized in that: described electrode diaphragm is also containing the electrolyte transmitter for transmitting or store electrolyte.
5. thick electrode according to claim 4, is characterized in that: described electrolyte transmitter is carbon nano-tube and/or carbon fiber.
6. thick electrode according to claim 1, is characterized in that: the thickness of described internal layer diaphragm is 1% ~ 90% of thick electrode thickness, and the thickness of outer diaphragm is 10% ~ 99% of thick electrode thickness.
7. thick electrode according to claim 1, is characterized in that: in described internal layer diaphragm, the mass content of conductive materials is 2% ~ 10%, in outer diaphragm conductive materials mass content 0% ~ 5%.
8. thick electrode according to claim 1, is characterized in that: described internal layer diaphragm is identical with the conductive materials of outer diaphragm, and in internal layer diaphragm, the content of conductive materials is greater than the content of conductive materials in outer diaphragm.
9. have a preparation method for the thick electrode of good electrical chemical property, it comprises the following steps:
A) collector is provided;
B) provide electrode diaphragm composition, containing active material, conductive materials and metal oxide in electrode diaphragm composition, metal oxide is selected from one or more in alundum (Al2O3), magnesium oxide, zinc oxide, zirconia;
C) apply one or more layers step b on a current collector) electrode diaphragm composition, through pore-creating and/or oven dry, form internal layer diaphragm, and;
D) in step c) obtained internal layer diaphragm applies one or more layers step b) electrode diaphragm composition, through pore-creating and/or oven dry, form outer diaphragm;
Steps d) in the porosity of outer diaphragm be greater than step c) in the porosity of internal layer diaphragm; Described step c) in the ion-transfer resistance of internal layer diaphragm be less than steps d) in the ion-transfer resistance of outer diaphragm; Described steps d) in the conductivity of outer diaphragm be less than step c) in the conductivity of internal layer diaphragm.
10. preparation method according to claim 9, is characterized in that: described step c) and steps d) in pore-creating be cold pressing treatment, described step c) in the pressure of cold pressing treatment be greater than described steps d) in the pressure of cold pressing treatment.
11. preparation methods according to claim 9, is characterized in that: described step b) electrode diaphragm composition in also containing pore creating material, described step c) and steps d) in pore-creating be heating, drying process.
12. preparation methods according to claim 11, is characterized in that: described pore creating material is one or more in benzoic acid, carbonic hydroammonium, Celogen Az.
13. preparation methods according to claim 9, is characterized in that: described electrode diaphragm composition is also containing the electrolyte transmitter for transmitting or store electrolyte.
14. preparation methods according to claim 9, is characterized in that: described internal layer diaphragm is identical with the conductive materials in outer diaphragm, and in internal layer diaphragm, the content of conductive materials is greater than the content of conductive materials in outer diaphragm.
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