CN112687863A - Lithium-sulfur battery positive electrode slurry, homogenizing method and application thereof - Google Patents
Lithium-sulfur battery positive electrode slurry, homogenizing method and application thereof Download PDFInfo
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Abstract
The invention provides a lithium-sulfur battery positive electrode slurry, a homogenizing method and application thereof, wherein the homogenizing method comprises the following steps: and stirring and dispersing the conductive agent and the binder in a solvent to obtain a mixed solution, and adding the positive electrode material into the mixed solution to prepare the positive electrode slurry of the lithium-sulfur battery. The viscosity of the lithium-sulfur battery positive electrode slurry is 2000-8000 mPa & s. The invention firstly soaks the conductive agent or the binder, which is helpful for slowing down the agglomeration of the conductive agent or the binder, thereby further improving the dispersibility of the conductive agent, the binder and the anode material, effectively solving the problem of anode slurry chap on the surface of the anode piece during coating, and ensuring that the single-side surface density of the anode slurry of the lithium-sulfur battery on the anode piece can reach the level of8mg/cm2The method has the characteristics of simple production process, batch production, low cost and the like.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, relates to a lithium-sulfur battery positive electrode slurry, and particularly relates to a lithium-sulfur battery positive electrode slurry, a homogenizing method and application thereof.
Background
The lithium-sulfur battery has the advantages of high theoretical energy density, abundant and easily available raw materials and low price, can be widely applied to the fields of aerospace, new energy automobiles and the like, and is one of the main development directions of next-generation high-specific-energy batteries. The lithium-sulfur battery is a novel lithium battery which is recognized at present and can reach the energy density of more than 400 Wh/kg. However, there are still many obstacles to its commercialization, such as the polysulfide shuttling effect and the negative lithium dendrite problem.
From the viewpoint of improving the energy density of the lithium-sulfur battery, the core problem is the improvement of the positive electrode surface capacity, and the positive electrode surface capacity is mainly related to the specific capacity of the positive electrode material and the surface density of the positive electrode pole piece. Therefore, the positive electrode material with high specific capacity is prepared into the positive plate of the high-capacity lithium-sulfur battery, and the utilization rate of the active substances is ensured, so that the design and the manufacture of the high-specific-energy lithium-sulfur battery are more than half completed.
At present, the research on the high-specific-energy lithium-sulfur battery still remains in the development of the high-specific-capacity positive electrode material, and the preparation method of the positive electrode plate mainly comprises the steps of simply mixing and stirring the active substance, the conductive agent and the binder and then coating the mixture. The method is difficult to ensure the full dispersion of the active substance, the conductive agent and the binding agent, and the agglomeration of the active substance and the conductive agent often occurs, so that the coated positive pole piece with high surface density is obviously cracked. Technically, the continuous production of the high-specific-energy lithium-sulfur battery positive electrode is difficult to realize.
CN105098143A discloses a flexible high-sulfur load self-repairing positive electrode structure of a lithium-sulfur battery and a preparation method thereof. The positive electrode structure of the lithium-sulfur battery is composed of graphene/high-molecular polymer flexible foam and a carbon/sulfur active material layer, wherein the active material is sulfur, and the graphene/high-molecular polymer flexible foam provides strength and a self-repairing function. The method has the characteristics that the multi-component integrated design of the lithium-sulfur battery is realized, the sulfur content is improved while the high electrochemical performance is ensured, the high active material surface density of the battery is realized, and the obtained lithium-sulfur battery has the advantages of high specific capacity and high specific energy density and also has the characteristics of flexibility and self-repairing. However, the preparation difficulty of the flexible foam mentioned by the method is high, and the sulfur infiltration technology is difficult to ensure the uniformity. The method has complex process and is difficult to realize batch production.
CN109346678A provides a preparation method of a high-sulfur-supported lithium-sulfur battery positive electrode, comprising the following steps: adding a carbon material and sulfur into water, and uniformly mixing to obtain carbon-sulfur mixed slurry; adding the carbon-sulfur mixed slurry into a sand mill for nano ball milling, drying and crushing, and then heating and melting to obtain a carbon-sulfur composite positive electrode material; adding a conductive agent, an adhesive and a carbon-sulfur composite positive electrode material into water, uniformly mixing to obtain a lithium-sulfur battery positive electrode slurry precursor, and then adding the positive electrode slurry precursor into a sand mill for nano ball milling to obtain lithium-sulfur battery positive electrode slurry; and uniformly coating the lithium-sulfur battery positive electrode slurry on an aluminum foil, and drying to obtain the high-sulfur load lithium-sulfur battery positive electrode. The method has the advantages of low raw material cost, simple process and controllable process, and is beneficial to preparing the lithium-sulfur battery anode with high sulfur loading capacity. However, the problem of uneven dispersion still exists during the mixing process.
The existing lithium-sulfur battery anode slurry has the characteristics of uneven dispersion and the like, so that the problem that how to ensure the uniform dispersion of the lithium-sulfur battery anode material is required to be solved at present is solved on the premise that the lithium-sulfur battery anode slurry is simple in production process, can be produced in batches, is low in cost and the like.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide the lithium-sulfur battery positive electrode slurry, the homogenizing method and the application thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for homogenizing positive electrode slurry for a lithium-sulfur battery, the method comprising:
and stirring, dissolving and dispersing the conductive agent and the binder in the solvent to obtain a mixed solution, and adding the positive electrode material into the mixed solution to prepare the positive electrode slurry of the lithium-sulfur battery.
The invention firstly soaks the conductive agent or the binder, which is helpful to slow down the agglomeration of the conductive agent or the binder, thereby further improving the dispersibility of the conductive agent, the binder and the anode material and effectively solving the problem that the anode slurry on the surface of the anode pole piece is chapped when coating, which affects the performance of the lithium-sulfur battery. The invention has the characteristics of simple production process, batch production, low cost and the like.
As a preferred embodiment of the present invention, the homogenization method comprises: and dissolving and dispersing the binder and the conductive agent in the solvent in sequence to obtain a mixed solution, and adding the positive electrode material into the mixed solution to prepare the positive electrode slurry of the lithium-sulfur battery.
According to the invention, the adhesive is firstly added into the solvent for infiltration, and then the conductive agent and the anode material are added, so that the dispersibility of the conductive agent, the adhesive and the anode material is good.
As a preferred embodiment of the present invention, the homogenization method specifically comprises the following steps:
adding a binder into a solvent, and stirring and dissolving to obtain a binder solution;
and (II) adding a conductive agent into the binder solution obtained in the step (I), stirring and mixing, stirring for a certain time after the conductive agent is added to obtain a mixed solution, and adding a positive electrode material to mix to obtain the lithium-sulfur battery positive electrode slurry.
In a preferred embodiment of the present invention, in step (i), the binder solution has a solid content of 2 to 50%, for example, a solid content of 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%.
According to the invention, the solid content of the binder is prepared to be within the range of 2-50%, so that the binder, the positive electrode material and the conductive agent are contacted more fully in the subsequent steps, and the dispersion effect of the positive electrode slurry is further improved, if the solid content of the binder is lower than 2%, the viscosity is too low in the mixing process, the particle aggregates are not easy to disperse, and the problems of large slurry granularity and uneven dispersion of the conductive agent are easy to occur; if the solid content of the binder is more than 50%, the binder, the positive electrode material, and the conductive agent are seriously agglomerated during the mixing process.
Preferably, in the step (I), the revolution speed of the stirring is 10-50 r/min, for example, the revolution speed is 10r/min, 15r/min, 20r/min, 25r/min, 30r/min, 35r/min, 40r/min, 45r/min or 50 r/min.
Preferably, in step (I), the stirring rotation speed is 1000-2500 r/min, for example, 1000r/min, 1100r/min, 1200r/min, 1300r/min, 1400r/min, 1500r/min, 1600r/min, 1700r/min, 1800r/min, 1900r/min, 2000r/min, 2100r/min, 2200r/min, 2300r/min, 2400r/min or 2500 r/min.
According to the invention, the revolution speed and the rotation speed of the binder in the stirring and dissolving process are controlled, when the rotation speed is controlled to be 1000-2500 r/min, the binder is fully dissolved, and if the rotation speed is lower than 1000r/min, the binder cannot be fully dissolved to form a uniform binder solution; if the rotation speed is higher than 2500r/min, the structure of the adhesive can be damaged due to high shear rate during stirring, and the bonding effect is influenced.
Preferably, in step (i), the stirring time is 1 to 6 hours, for example, 1.0 hour, 1.5 hours, 2.0 hours, 2.5 hours, 3.0 hours, 3.5 hours, 4.0 hours, 4.5 hours, 5.0 hours, 5.5 hours or 6.0 hours.
According to the invention, the stirring time in the stirring and dissolving process of the binder is controlled, when the stirring time is controlled to be 1-6 h, the binder can be fully dissolved, and if the stirring time is less than 1h, the binder cannot be fully dissolved to form a uniform binder solution; if the stirring time is longer than 6 hours, on one hand, the structure of the binder can be damaged, and on the other hand, the energy consumption of equipment is high, and resources are wasted.
Preferably, in step (ii), the conductive agent is added to the binder solution of step (i) at least twice.
According to the invention, the conductive agent is added at least twice, so that the problem of agglomeration of the conductive agent is reduced, and the dispersion effect of the conductive agent can be effectively improved.
Preferably, in the step (II), the revolution speed of the stirring is 10-50 r/min, for example, the revolution speed is 10r/min, 15r/min, 20r/min, 25r/min, 30r/min, 35r/min, 40r/min, 45r/min or 50 r/min.
Preferably, in the step (II), the rotation speed of the stirring is 500-2500 r/min, for example, 500r/min, 700r/min, 900r/min, 1100r/min, 1300r/min, 1500r/min, 1700r/min, 1900r/min, 2100r/min, 2300r/min or 2500 r/min.
According to the invention, by controlling the revolution speed and the rotation speed in the dispersing process of the conductive agent, when the rotation speed is controlled to be 500-2500 r/min, agglomerated particles of the conductive agent are fully refined and dispersed, and if the rotation speed is lower than 500r/min, the effect of fully dispersing the conductive agent powder cannot be achieved; if the rotation speed is higher than 2500r/min, the conductive agent powder is uniformly dispersed due to the excessively high rotation speed during the stirring process, but the high shear rate may cause structural damage of the binder and reduce the cohesiveness.
Preferably, in the step (II), the certain time is 30-120 min, for example, 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min or 120 min.
According to the invention, the stirring time in the dispersing process of the conductive agent is controlled to be 30-120 min, so that the conductive agent can be fully dissolved, and if the stirring time is less than 30min, the effect of fully dispersing the conductive agent powder cannot be achieved; if the stirring time is more than 120min, the energy consumption of the equipment is large, and resources are wasted.
As a preferred embodiment of the present invention, the homogenization method comprises: and sequentially dissolving a conductive agent and a binder in a solvent to obtain a mixed solution, and adding a positive electrode material into the mixed solution to prepare the positive electrode slurry of the lithium-sulfur battery.
According to the invention, the conductive agent is soaked firstly, so that the conductive agent agglomeration condition brought by adding the binder is favorably slowed down, and the dispersion effect of the lithium-sulfur battery anode slurry is further improved.
As a preferred embodiment of the present invention, the homogenization method specifically comprises the following steps:
(1) adding a conductive agent into a solvent, and stirring and mixing to obtain a conductive agent solution;
(2) and (2) adding a binder into the binder solution obtained in the step (1), stirring and mixing to obtain a mixed solution, and adding a positive electrode material for mixing to obtain the lithium-sulfur battery positive electrode slurry.
As a preferable embodiment of the present invention, in the step (1), the revolution speed of the stirring is 10 to 20r/min, for example, the revolution speed is 10r/min, 11r/min, 12r/min, 13r/min, 14r/min, 15r/min, 16r/min, 17r/min, 18r/min, 19r/min or 20 r/min.
Preferably, in the step (1), the rotation speed of the stirring is 1000-2000 r/min, for example, 1000r/min, 1100r/min, 1200r/min, 1300r/min, 1400r/min, 1500r/min, 1600r/min, 1700r/min, 1800r/min, 1900r/min or 2000 r/min.
According to the invention, by controlling the revolution speed and the rotation speed in the dispersing process of the conductive agent, when the rotation speed is controlled to be 1000-2500 r/min, agglomerated particles of the conductive agent are fully refined and dispersed, and if the rotation speed is lower than 1000r/min, the effect of fully dispersing conductive agent powder cannot be achieved; if the rotation speed is higher than 2500r/min, the conductive agent powder is washed onto the wall of the stirring cylinder by the solvent due to the centrifugal force in the stirring process because of the over-high rotation speed, and the dispersion effect is influenced.
Preferably, in the step (1), the stirring time is 30-120 min, for example, 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min or 120 min.
Preferably, in the step (2), the revolution speed of the stirring is 10-50 r/min, for example, the revolution speed is 10r/min, 15r/min, 20r/min, 25r/min, 30r/min, 35r/min, 40r/min, 45r/min or 50 r/min.
Preferably, in the step (2), the rotation speed of the stirring is 500-2000 r/min, for example, 500r/min, 600r/min, 700r/min, 800r/min, 900r/min, 1000r/min, 1100r/min, 1200r/min, 1300r/min, 1400r/min, 1500r/min, 1600r/min, 1700r/min, 1800r/min, 1900r/min or 2000 r/min.
According to the invention, by controlling the revolution speed and the rotation speed in the mixing process of the conductive agent and the binder, when the rotation speed is controlled to be 500-2500 r/min, the conductive agent agglomerated particles are fully mixed with the binder, and if the rotation speed is lower than 500r/min, the effect of fully dispersing the conductive agent powder cannot be achieved; if the rotation speed is higher than 2500r/min, the conductive agent powder is uniformly dispersed due to the excessively high rotation speed during the stirring process, but the high shear rate may cause structural damage of the binder.
Preferably, in the step (2), the stirring time is 30-120 min, for example, 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min or 120 min.
According to the invention, the stirring time in the mixing process of the binder and the conductive agent is controlled to be 30-120 min, so that the binder and the conductive agent can be fully and uniformly mixed, and if the stirring time is less than 30min, the binder and the conductive agent solution are not uniformly mixed; if the stirring time is more than 120min, on one hand, the structure of the binder can be damaged, and on the other hand, the energy consumption of equipment is large, and resources are wasted.
As a preferred technical scheme of the invention, the positive electrode material is added into the mixed solution, and is firstly stirred and mixed for the first time, and after the positive electrode material is added, the positive electrode material is stirred for the second time to prepare the positive electrode slurry of the lithium-sulfur battery.
Preferably, the secondary stirring is followed by defoaming and sieving treatments in sequence.
Preferably, the mesh number of the sieving treatment is 100-200 meshes, for example, the mesh number is 100 meshes, 110 meshes, 120 meshes, 130 meshes, 140 meshes, 150 meshes, 160 meshes, 170 meshes, 180 meshes, 190 meshes or 200 meshes.
Preferably, the positive electrode material is added to the mixed solution at least twice.
According to the invention, the anode material is added at least twice, so that the dispersibility of the anode material is improved, and the agglomeration of the anode material is avoided.
Preferably, the revolution speed of the primary stirring is 10-50 r/min, for example, the revolution speed is 10r/min, 15r/min, 20r/min, 25r/min, 30r/min, 35r/min, 40r/min, 45r/min or 50 r/min.
Preferably, the rotation speed of the primary stirring is 500-2500 r/min, for example, 500r/min, 700r/min, 900r/min, 1100r/min, 1300r/min, 1500r/min, 1700r/min, 1900r/min, 2100r/min, 2300r/min or 2500 r/min.
Preferably, the revolution speed of the secondary stirring is 30-70 r/min, for example, the revolution speed is 30r/min, 35r/min, 40r/min, 45r/min, 50r/min, 55r/min, 60r/min, 65r/min or 70 r/min.
Preferably, the rotation speed of the secondary stirring is 1000-2500 r/min, for example, 1000r/min, 1100r/min, 1200r/min, 1300r/min, 1400r/min, 1500r/min, 1600r/min, 1700r/min, 1800r/min, 1900r/min, 2000r/min, 2100r/min, 2200r/min, 2300r/min, 2400r/min or 2500 r/min.
Preferably, the time of the secondary stirring is 3 to 9 hours, for example, 3.0 hours, 3.5 hours, 4.0 hours, 4.5 hours, 5.0 hours, 5.5 hours, 6.0 hours, 6.5 hours, 7.0 hours, 7.5 hours, 8.0 hours, 8.5 hours or 9.0 hours.
Preferably, the conductive agent comprises one or a combination of at least two of conductive carbon black, conductive graphite, carbon nanotubes or carbon fibers.
Preferably, the binder comprises one or a combination of at least two of polyvinylidene fluoride, sodium carboxymethylcellulose, polyacrylic acid, polyacrylonitrile or sodium alginate.
Preferably, the solvent comprises one or a combination of at least two of deionized water, N-methyl pyrrolidone or alcohol organic matters.
Preferably, the alcohol organic substance comprises one or a combination of at least two of ethanol, isopropanol or n-propanol.
Preferably, the positive electrode material comprises one or a combination of at least two of a sulfur-carbon composite, a sulfur-polymer composite, or a metal sulfide.
It should be noted that the invention does not make specific requirements and special restrictions on the material of the carbon composite material, the sulfur polymer composite material or the metal sulfide, and those skilled in the art can reasonably select the material according to the operation requirements, optionally, the sulfur-graphene composite material, the sulfur-polyacrylonitrile composite material or the lithium sulfide-graphene composite material; the sulfur-graphene composite material can be prepared by adopting a CN103187570A method, the lithium sulfide-graphene composite material can be prepared by adopting a CN105609768A method, and the sulfur-polyacrylonitrile composite material can be prepared by adopting a CN103502284A method, so that the dispersibility of a homogenization method is not substantially influenced by the cathode material adopted in the invention.
Illustratively, two methods for homogenizing the lithium-sulfur battery positive electrode slurry are provided, wherein one method specifically comprises the following steps:
adding a binder into a solvent, and stirring and mixing to obtain a binder solution with the solid content of 2-50%, wherein the stirring revolution speed is 10-50 r/min, the rotation speed is 1000-2500 r/min, and the stirring time is 1-6 h;
(II) adding the conductive agent into the binder solution obtained in the step (I) at least twice, stirring and mixing, and stirring for 30-120 min to obtain a mixed solution after the conductive agent is added, wherein the stirring revolution speed is 10-50 r/min, and the rotation speed is 500-2500 r/min; adding the anode materials at least twice for one time, and mixing, wherein the revolution speed of one-time stirring is 10-50 r/min, and the rotation speed is 500-2500 r/min; and then carrying out secondary stirring, wherein the revolution speed of the secondary stirring is 30-70 r/min, the rotation speed is 1000-2500 r/min, and the time is 3-9 h, and finally carrying out defoaming and sieving treatment, wherein the mesh number of the sieving treatment is 100-200 meshes, so as to prepare the lithium-sulfur battery anode slurry.
Secondly, the homogenization method specifically comprises the following steps:
(1) adding a conductive agent into a solvent, stirring and mixing to obtain a conductive agent solution, wherein the stirring revolution speed is 10-20 r/min, the rotation speed is 1000-2000 r/min, and the time is 30-120 min;
(2) adding a binder into the binder solution obtained in the step (1), and stirring and mixing to prepare a mixed solution, wherein the stirring revolution speed is 10-50 r/min, the rotation speed is 500-2000 r/min, and the stirring time is 30-120 min; adding the anode materials at least twice for one time, and mixing, wherein the revolution speed of one-time stirring is 10-50 r/min, and the rotation speed is 500-2500 r/min; and then carrying out secondary stirring, wherein the revolution speed of the secondary stirring is 30-70 r/min, the rotation speed is 1000-2500 r/min, and the time is 3-9 h, and finally carrying out defoaming and sieving treatment, wherein the mesh number of the sieving treatment is 100-200 meshes, so as to prepare the lithium-sulfur battery anode slurry.
In a second aspect, the present invention provides a lithium-sulfur battery positive electrode slurry prepared by the method for homogenizing a lithium-sulfur battery positive electrode slurry according to the first aspect, wherein the lithium-sulfur battery positive electrode slurry has a viscosity of 2000 to 8000mPa · s, for example, 2000mPa · s, 2500mPa · s, 3000mPa · s, 3400mPa · s, 3800mPa · s, 4200mPa · s, 4600mPa · s, 5000mPa · s, 5400mPa · s, 5800mPa · s, 6200mPa · s, 6600mPa · s, 7000mPa · s, 7200mPa · s, 7600mPa · s, or 8000mPa · s.
In a third aspect, the invention provides a lithium-sulfur battery, which comprises a positive plate, wherein the positive plate comprises a current collector and lithium-sulfur battery positive slurry coated on the surface of the current collector, the lithium-sulfur battery positive slurry is the lithium-sulfur battery positive slurry in the second aspect, and the single-side surface density of the lithium-sulfur battery positive slurry on the positive plate is more than or equal to 8mg/cm2For example, the areal density of one side is 8mg/cm2、9mg/cm2、10mg/cm2、11mg/cm2、12mg/cm2、13mg/cm2、14mg/cm2、15mg/cm2Or 16mg/cm2(ii) a The current collector is made of aluminum foil and/or carbon-coated aluminum foil.
It should be noted that the preparation method of the positive electrode plate of the present invention is not specifically required or limited, and those skilled in the art can reasonably select the preparation method according to the operation requirements, for example, the positive electrode slurry of the lithium-sulfur battery is coated on a current collector, the solvent is dried at 60 to 120 ℃, and the positive electrode plate is prepared by adjusting the gap between scrapers.
The recitation of numerical ranges herein includes not only the above-recited numerical values, but also any numerical values between non-recited numerical ranges, and is not intended to be exhaustive or to limit the invention to the precise numerical values encompassed within the range for brevity and clarity.
Compared with the prior art, the invention has the beneficial effects that:
the invention firstly soaks the conductive agent or the binder, which is helpful for slowing down the agglomeration of the conductive agent or the binder, thereby further improving the dispersibility of the conductive agent, the binder and the anode material, and effectively solving the problem of chapping of the anode slurry on the surface of the anode piece during coating2The method has the characteristics of simple production process, batch production, low cost and the like.
Drawings
Fig. 1 is a process flow diagram of a method for homogenizing a lithium sulfur battery positive electrode slurry provided in examples 1 to 3 of the present invention;
fig. 2 is a process flow diagram of a method for homogenizing the positive electrode slurry of a lithium sulfur battery provided in examples 4 to 6 of the present invention.
Detailed Description
In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the present invention, which is defined by the claims.
The technical solution of the present invention is further explained by the following embodiments.
Example 1
The embodiment provides a lithium-sulfur battery positive electrode slurry, wherein a positive electrode material is a sulfur-graphene composite material, a conductive agent is conductive carbon black, a binder is polyvinylidene fluoride, a solvent is N-methylpyrrolidone, and the adding mass ratio of the positive electrode material to the conductive agent to the binder to the solvent is 82: 10: 8; the viscosity of the lithium-sulfur battery positive electrode slurry is 6500mPa & s.
This embodiment also provides a method for homogenizing the above-mentioned positive electrode slurry for a lithium-sulfur battery, as shown in fig. 1, where the method specifically includes:
adding an adhesive into a solvent, and stirring and mixing to obtain an adhesive solution with the solid content of 6%, wherein the stirring revolution speed is 25r/min, the rotation speed is 1750r/min, and the stirring time is 3.5 h;
(II) adding the conductive agent into the binder solution obtained in the step (I) twice, stirring and mixing, and stirring for 75min to obtain a mixed solution after the conductive agent is added, wherein the stirring revolution speed is 30r/min, and the rotation speed is 1500 r/min; adding the anode material for three times for mixing once, wherein the revolution speed of one-time stirring is 30r/min, and the rotation speed is 1500 r/min; and then carrying out secondary stirring, wherein the revolution speed of the secondary stirring is 50r/min, the rotation speed is 1750r/min, and the time is 6h, finally carrying out defoaming and sieving treatment, wherein the mesh number of the sieving treatment is 150 meshes, and preparing the lithium-sulfur battery anode slurry.
The embodiment also provides a lithium-sulfur battery comprising the lithium-sulfur battery positive electrode slurry, wherein the single-side surface density of the lithium-sulfur battery positive electrode slurry on the positive electrode sheet is 10mg/cm2。
Example 2
The embodiment provides a lithium-sulfur battery positive electrode slurry, wherein a positive electrode material is a sulfur-polyacrylonitrile composite material, a conductive agent is conductive graphite, a binder is sodium carboxymethyl cellulose, a solvent is deionized water, and the adding mass ratio of the positive electrode material to the conductive agent to the binder to the solvent is 82: 10: 8; the viscosity of the positive electrode slurry of the lithium-sulfur battery is 3500mPa & s.
This embodiment also provides a method for homogenizing the above-mentioned positive electrode slurry for a lithium-sulfur battery, as shown in fig. 1, where the method specifically includes:
adding an adhesive into a solvent, and stirring and mixing to obtain an adhesive solution with the solid content of 2%, wherein the stirring revolution speed is 50r/min, the rotation speed is 1000r/min, and the stirring time is 1 h;
(II) adding the conductive agent into the binder solution obtained in the step (I) for three times, stirring and mixing, and stirring for 120min to obtain a mixed solution after the conductive agent is added, wherein the stirring revolution speed is 10r/min, and the rotation speed is 2500 r/min; adding the anode materials twice for mixing once, wherein the revolution speed of one-time stirring is 50r/min, and the rotation speed is 500 r/min; and then carrying out secondary stirring, wherein the revolution speed of the secondary stirring is 30r/min, the rotation speed is 2500r/min, and the time is 3h, finally carrying out defoaming and sieving treatment, and the mesh number of the sieving treatment is 100 meshes, thus preparing the lithium-sulfur battery anode slurry.
The embodiment also provides a lithium-sulfur battery comprising the lithium-sulfur battery positive electrode slurry, wherein the single-side surface density of the lithium-sulfur battery positive electrode slurry on the positive electrode sheet is 8mg/cm2。
Example 3
The embodiment provides a lithium-sulfur battery positive electrode slurry, wherein a positive electrode material is a lithium sulfide-graphene compound, a conductive agent is a carbon nano tube, a binder is polyvinylidene fluoride, a solvent is N-methylpyrrolidone, and the adding mass ratio of the positive electrode material to the conductive agent to the binder to the solvent is 82: 12: 6; the viscosity of the lithium-sulfur battery positive electrode slurry is 4600mPa & s.
This embodiment also provides a method for homogenizing the above-mentioned positive electrode slurry for a lithium-sulfur battery, as shown in fig. 1, where the method specifically includes:
adding a binder into a solvent, and stirring and mixing to obtain a binder solution with the solid content of 8%, wherein the stirring revolution speed is 10r/min, the rotation speed is 2500r/min, and the stirring time is 6 hours;
(II) adding the conductive agent into the binder solution obtained in the step (I) for four times, stirring and mixing, and stirring for 30min to obtain a mixed solution after the conductive agent is added, wherein the stirring revolution speed is 50r/min, and the rotation speed is 500 r/min; adding the anode material for one time and mixing for five times, wherein the revolution speed of one-time stirring is 10r/min, and the rotation speed is 2500 r/min; and then secondary stirring is carried out, the revolution speed of the secondary stirring is 70r/min, the rotation speed is 1000r/min, the time is 9 hours, finally defoaming and sieving treatment are carried out, and the mesh number of the sieving treatment is 200 meshes, so that the lithium-sulfur battery anode slurry is prepared.
The embodiment also provides a lithium-sulfur battery comprising the lithium-sulfur battery positive electrode slurry, wherein the single-side surface density of the lithium-sulfur battery positive electrode slurry on the positive electrode sheet is 9mg/cm2。
Example 4
The embodiment provides a lithium-sulfur battery positive electrode slurry, wherein a positive electrode material is a sulfur-graphene composite material, a conductive agent is carbon fiber, a binder is a polyacrylonitrile copolymer, a solvent is a mixed solvent of deionized water and isopropanol, the mixing volume ratio is 4:1, and the adding mass ratio of the positive electrode material to the conductive agent to the binder to the solvent is 80: 12: 8; the viscosity of the lithium-sulfur battery positive electrode slurry is 5900mPa & s.
This embodiment also provides a method for homogenizing the above-mentioned positive electrode slurry for a lithium-sulfur battery, as shown in fig. 2, where the method specifically includes:
(1) adding a conductive agent into a solvent, stirring and mixing to obtain a conductive agent solution, wherein the stirring revolution speed is 15r/min, the rotation speed is 1500r/min, and the time is 75 min;
(2) adding a binder into the binder solution obtained in the step (1), stirring and mixing to prepare a mixed solution, wherein the stirring revolution speed is 30r/min, the rotation speed is 1250r/min, and the stirring time is 75 min; adding the anode materials for four times for mixing once, wherein the revolution speed of one-time stirring is 20r/min, and the rotation speed is 1000 r/min; and then carrying out secondary stirring, wherein the revolution speed of the secondary stirring is 40r/min, the rotation speed is 1450r/min, and the time is 4 hours, and finally carrying out defoaming and sieving treatment, wherein the mesh number of the sieving treatment is 130 meshes, so as to prepare the lithium-sulfur battery anode slurry.
The embodiment also provides a lithium-sulfur battery comprising the lithium-sulfur battery positive electrode slurry, wherein the single-side surface density of the lithium-sulfur battery positive electrode slurry on the positive electrode sheet is 12mg/cm2。
Example 5
The embodiment provides a lithium-sulfur battery positive electrode slurry, wherein a positive electrode material is a sulfur-polyacrylonitrile composite material, a conductive agent is conductive graphite, a binder is sodium alginate, a solvent is a mixed solvent of deionized water and n-propanol, the mixing volume ratio is 5:1, and the adding mass ratio of the positive electrode material to the conductive agent to the binder to the solvent is 82: 10: 8; the viscosity of the positive electrode slurry of the lithium-sulfur battery is 3900mPa & s.
This embodiment also provides a method for homogenizing the above-mentioned positive electrode slurry for a lithium-sulfur battery, as shown in fig. 2, where the method specifically includes:
(1) adding a conductive agent into a solvent, stirring and mixing to obtain a conductive agent solution, wherein the stirring revolution speed is 10r/min, the rotation speed is 2000r/min, and the time is 120 min;
(2) adding the binder into the binder solution obtained in the step (1), and stirring and mixing to prepare a mixed solution, wherein the stirring revolution speed is 10r/min, the rotation speed is 2000r/min, and the stirring time is 30 min; adding the anode material for eight times for mixing once, wherein the revolution speed of one-time stirring is 40r/min, and the rotation speed is 1750 r/min; and then secondary stirring is carried out, the revolution speed of the secondary stirring is 60r/min, the rotation speed is 2000r/min, the time is 5 hours, finally defoaming and sieving treatment are carried out, and the mesh number of the sieving treatment is 160 meshes, so that the lithium-sulfur battery anode slurry is prepared.
The embodiment also provides a lithium-sulfur battery comprising the lithium-sulfur battery positive electrode slurry, wherein the single-side surface density of the lithium-sulfur battery positive electrode slurry on the positive electrode sheet is 13mg/cm2。
Example 6
The embodiment provides a lithium-sulfur battery positive electrode slurry, wherein a positive electrode material is a lithium sulfide-graphene compound, a conductive agent is a carbon nano tube, a binder is polyvinylidene fluoride, a solvent is N-methylpyrrolidone, and the adding mass ratio of the positive electrode material to the conductive agent to the binder to the solvent is 82: 12: 6; the viscosity of the positive electrode slurry of the lithium-sulfur battery is 5000mPa & s.
This embodiment also provides a method for homogenizing the above-mentioned positive electrode slurry for a lithium-sulfur battery, as shown in fig. 2, where the method specifically includes:
(1) adding a conductive agent into a solvent, stirring and mixing to obtain a conductive agent solution, wherein the stirring revolution speed is 20r/min, the rotation speed is 1000r/min, and the time is 30 min;
(2) adding the binder into the binder solution obtained in the step (1), and stirring and mixing to prepare a mixed solution, wherein the stirring revolution speed is 50r/min, the rotation speed is 500r/min, and the stirring time is 120 min; adding the anode material for seven times for mixing once, wherein the revolution speed of one-time stirring is 35r/min, and the rotation speed is 1250 r/min; and then carrying out secondary stirring, wherein the revolution speed of the secondary stirring is 55r/min, the rotation speed is 2200r/min, and the time is 8h, finally carrying out defoaming and sieving treatment, and the mesh number of the sieving treatment is 180 meshes, thus preparing the lithium-sulfur battery anode slurry.
The embodiment also provides a lithium-sulfur battery comprising the lithium-sulfur battery positive electrode slurry, wherein the single-side surface density of the lithium-sulfur battery positive electrode slurry on the positive electrode sheet is 15mg/cm2。
Comparative example 1
The comparative example provides a method for homogenizing lithium-sulfur battery positive electrode slurry, wherein the positive electrode material, the conductive agent, the binder and the solvent are the same as those in example 1, and the homogenizing method specifically comprises the following steps:
and adding the binder, the conductive agent and the positive electrode material into the solvent, stirring and mixing, wherein the revolution speed of stirring is 10-50 r/min, the rotation speed is 1000-2500 r/min, and the total stirring time is the same as that in the embodiment 1.
And (4) defoaming and sieving, wherein the sieving mesh number is 150 meshes, and the viscosity of the prepared lithium-sulfur battery positive electrode slurry is 3800mPa & s.
The comparative example also provides a lithium sulfur battery comprising the above-described positive electrode slurry for a lithium sulfur battery, wherein the single-sided areal density of the positive electrode slurry for a lithium sulfur battery on the positive electrode sheet is 8mg/cm2And obvious cracks occur on the coating layer of the positive electrode material on the positive electrode plate.
Compared with the comparative example 1, the embodiment 1-6 shows that by adopting the homogenizing method of the lithium-sulfur battery anode slurry provided by the invention, the conductive agent or the binder is soaked, so that the dispersion effect of the anode material, the conductive agent, the binder and the solvent is improved, the viscosity of the anode slurry can further meet the use requirement, and the problem that a coating layer has cracks when a cathode pole piece is prepared is effectively avoided.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (10)
1. A homogenization method of positive electrode slurry of a lithium-sulfur battery is characterized by comprising the following steps:
and stirring, dissolving and dispersing the conductive agent and the binder in the solvent to obtain a mixed solution, and adding the positive electrode material into the mixed solution to prepare the positive electrode slurry of the lithium-sulfur battery.
2. A homogenization method according to claim 1, wherein the homogenization method comprises: and dissolving and dispersing the binder and the conductive agent in the solvent in sequence to obtain a mixed solution, and adding the positive electrode material into the mixed solution to prepare the positive electrode slurry of the lithium-sulfur battery.
3. A homogenization method according to claim 2, which comprises in particular the following steps:
adding a binder into a solvent, and stirring and dissolving to obtain a binder solution;
and (II) adding a conductive agent into the binder solution obtained in the step (I), stirring and mixing, stirring for a certain time after the conductive agent is added to obtain a mixed solution, and adding a positive electrode material to mix to obtain the lithium-sulfur battery positive electrode slurry.
4. A homogenization method according to claim 3, wherein in step (i), the binder solution has a solid content of 2 to 50%;
preferably, in the step (I), the revolution speed of the stirring is 10-50 r/min;
preferably, in the step (I), the rotation speed of the stirring is 1000-2500 r/min;
preferably, in the step (I), the stirring time is 1-6 h;
preferably, in the step (II), the conductive agent is added into the binder solution in the step (I) at least twice;
preferably, in the step (II), the revolution speed of the stirring is 10-50 r/min;
preferably, in the step (II), the rotation speed of the stirring is 500-2500 r/min;
preferably, in the step (II), the certain time is 30-120 min.
5. A homogenization method according to claim 1, wherein the homogenization method comprises: and sequentially dissolving a conductive agent and a binder in a solvent to obtain a mixed solution, and adding a positive electrode material into the mixed solution to prepare the positive electrode slurry of the lithium-sulfur battery.
6. A homogenization method according to claim 5, which comprises in particular the following steps:
(1) adding a conductive agent into a solvent, and stirring and mixing to obtain a conductive agent solution;
(2) and (2) adding a binder into the binder solution obtained in the step (1), stirring and mixing to obtain a mixed solution, and adding a positive electrode material for mixing to obtain the lithium-sulfur battery positive electrode slurry.
7. The homogenizing method according to claim 6, wherein in the step (1), the revolution speed of the stirring is 10 to 20 r/min;
preferably, in the step (1), the rotation speed of the stirring is 1000-2000 r/min;
preferably, in the step (1), the stirring time is 30-120 min;
preferably, in the step (2), the revolution speed of the stirring is 10-50 r/min;
preferably, in the step (2), the rotation speed of the stirring is 500-2000 r/min;
preferably, in the step (2), the stirring time is 30-120 min.
8. The homogenizing method according to any one of claims 1 to 7, wherein the positive electrode material is added to the mixed solution, and is subjected to primary stirring and mixing, and after the addition of the positive electrode material is completed, secondary stirring is performed to prepare the positive electrode slurry for the lithium-sulfur battery;
preferably, defoaming and sieving are sequentially carried out after the secondary stirring;
preferably, the mesh number of the sieving treatment is 100-200 meshes;
preferably, the positive electrode material is added to the mixed solution at least twice;
preferably, the revolution speed of the primary stirring is 10-50 r/min;
preferably, the rotation speed of the primary stirring is 500-2500 r/min;
preferably, the revolution speed of the secondary stirring is 30-70 r/min;
preferably, the rotation speed of the secondary stirring is 1000-2500 r/min;
preferably, the time of the secondary stirring is 3-9 h;
preferably, the conductive agent comprises one or a combination of at least two of conductive carbon black, conductive graphite, carbon nanotubes or carbon fibers;
preferably, the binder comprises one or a combination of at least two of polyvinylidene fluoride, sodium carboxymethylcellulose, polyacrylic acid copolymer, polyacrylonitrile copolymer or sodium alginate;
preferably, the solvent comprises one or a combination of at least two of deionized water, N-methyl pyrrolidone or alcohol organic matters;
preferably, the alcohol organic matter comprises one or a combination of at least two of ethanol, isopropanol or n-propanol;
preferably, the positive electrode material comprises one or a combination of at least two of a sulfur-carbon composite, a sulfur-polymer composite, or a metal sulfide.
9. The lithium-sulfur battery positive electrode slurry is prepared by the homogenization method of the lithium-sulfur battery positive electrode slurry according to any one of claims 1 to 8, and the viscosity of the lithium-sulfur battery positive electrode slurry is 2000-8000 mPa-s.
10. The lithium-sulfur battery is characterized by comprising a positive plate, wherein the positive plate comprises a current collector and lithium-sulfur battery positive slurry coated on the surface of the current collector, the lithium-sulfur battery positive slurry is the lithium-sulfur battery positive slurry according to claim 9, and the single-side surface density of the lithium-sulfur battery positive slurry on the positive plate is more than or equal to 8mg/cm2(ii) a The current collector is made of aluminum foil and/or carbon-coated aluminum foil.
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