CN105789629A - Method for improving lasting stability of fluid - Google Patents
Method for improving lasting stability of fluid Download PDFInfo
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- CN105789629A CN105789629A CN201410776957.5A CN201410776957A CN105789629A CN 105789629 A CN105789629 A CN 105789629A CN 201410776957 A CN201410776957 A CN 201410776957A CN 105789629 A CN105789629 A CN 105789629A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention provides a method for improving the lasting stability of fluid, which relates to the application of various fluids in different fields in the processes of preparation, transportation, storage and the like, and comprises various simple mechanical dispersions and stable colloidal dispersions. The method is mainly based on the colloid theory, and improves the stability of the fluid by adding inorganic micromolecule electrolyte, organic micromolecule electrolyte, polyelectrolyte, different surfactants and other stabilizers, thereby prolonging the gelation time of the fluid and eliminating the adverse phenomena of fluid precipitation, delamination and the like. The method can be applied to the slurry preparation process before the preparation of the positive and negative pole pieces in different battery systems such as zinc-manganese batteries, nickel-zinc batteries, nickel-cadmium batteries, silver-zinc batteries, lead-acid batteries, nickel-hydrogen batteries, lithium ion batteries, fuel batteries and the like, and ensures that the slurry deposition phenomenon does not occur in the pole piece coating process, thereby improving the consistency of the slurry and the consistency of the distribution of the slurry on a current collector.
Description
Technical Field
The invention relates to the field of fluid application, provides a method for durably stabilizing an organic system fluid, and particularly relates to a method for improving the stability of positive and negative electrode slurry in the field of lithium ion batteries.
Background
Industrial production involves a number of application problems related to fluid preparation, transport, storage. How to improve the stability of the fluid is a more important problem to be solved in industrial production. The fluid has poor stability, the fluid is easy to be layered in the preparation process, and the effective substances in the fluid are not uniformly distributed; when solid matter precipitates and remains in the process of transferring and conveying the fluid, the quality of the product is influenced, various conveying pipelines are blocked, the materials remaining on the pipelines not only pollute the product, but also influence the calculation of the content of the materials in the fluid, and the next experiment is not facilitated. In conclusion, the fluid is unstable in any step, and more manpower and material resources are needed for restoring the stability of the fluid subsequently.
At present, physical methods including simple mechanical stirring, electromagnetic stirring, ultrasonic stirring, heating and heat preservation are commonly adopted as methods for improving the stability of the fluid. The fluid obtained by the method has stability in a short time, and has no problem for small-scale field production; however, this type of process does not have advantages with large production scales, and the fluids clearly have a time stability weakening effect.
When the powder particles are dispersed in a polar medium (such as water, electrolyte-containing solution, etc.), the surface of the dispersed phase has a non-zero net surface charge due to unequal adsorption of counter ions, resulting in an interfacial potential difference. This net charge at the interface affects the distribution of ions in the medium surrounding the interface, ions in the medium of opposite sign to the interface charge being attracted to the interface, and ions of the same sign being expelled from the interface. At the same time, the thermal motion of the ions causes them to mix uniformly. Thus, a diffused electric double layer is formed at the charged interface. When an electrolyte is added to the dispersion system (or the pH is changed), the concentration difference between the diffusion layer and the solution decreases, and the diffusion of the counter ions into the solution decreases. Accordingly, the number of ions in the diffusion layer is reduced, the diffusion layer is compressed, and more counter ions enter the compact layer, thereby lowering the zeta potential. Two forces are interacted between the dispersed phases (powder particles) in the dispersion system, namely electrostatic repulsion force of an electric double layer and VanderWaals attraction force. The interaction energy of the two is a function of the distance between the particles, and the total potential energy between the particles is an energy barrier. The higher the energy barrier, the more dominant the electric double layer repulsion and the more stable the dispersion. When an electrolyte is added (or pH is changed), the potential drops, the diffusion layer is compressed, causing the repulsive force to drop, and the energy barrier to drop. Especially when attraction = repulsion, the energy barrier is zero (i.e. the isoelectric point of the dispersion). At this point, the VanderWaals force dominates and the particles tend to agglomerate. In addition to van der waals attraction and electric double layer repulsion, the stability of the dispersion containing the macromolecular surface-active substance is also affected by factors such as desorption energy, bridging effect, etc. For example, in a dispersion of powder particles in an organic solvent, macromolecular substances are adsorbed on the particle surface and the macromolecular chains will extend into the medium, causing interactions of these bonds when the particles are close to each other, accompanied by a decrease in entropy (decrease in degree of disorder,. DELTA.S < 0), which involves a positive free energy change (i.e.. DELTA.G =. DELTA.H-T. DELTA.S > 0) hindering aggregation of the particles since the enthalpy change (. DELTA.H) of the thermal effect is negligible. This is the theory of colloidal stability of the so-called dispersion (see FIG. 1).
Disclosure of Invention
In order to solve the problem of instability of fluid in the preparation, transportation and storage processes in the prior art, the invention provides a method for improving the lasting stability of the fluid, which can be used in the visible fluid field, especially the battery field, such as the preparation process of slurry of positive and negative electrode plates of lead-acid batteries, nickel-hydrogen batteries, lithium ion batteries, fuel batteries and the like.
The method can be used in the field of preparation of various battery pole pieces, and mainly comprises the steps of adding inorganic micromolecule electrolyte, organic micromolecule electrolyte, polymer electrolyte or surfactant and the like. Wherein the mass of the added stabilizer is 0-50 wt% of the mass of the fluid.
The slurry treated by the method has better lasting stability, the system viscosity is reduced to a certain degree, and the gelation time of the slurry can be effectively and greatly prolonged.
In the present invention, the selection of the stabilizer is crucial. The addition of the stabilizer (inorganic small molecular electrolyte, organic small molecular electrolyte, polymer electrolyte, surfactant and the like) can improve the lasting stability of the existing system, reduce the occurrence of gelation and sedimentation delamination phenomena, and does not influence the essential performance of the original system.
The stabilizer has the advantages of good compatibility with the existing system, low price cost, stable physical and chemical properties, environmental protection, no toxicity, no harm, abundant and easily obtained raw materials and the like.
The method for improving the lasting stability of the fluid can be realized by independently adopting one of inorganic small molecular electrolyte, organic small molecular electrolyte, polymer electrolyte or surfactant; or in combinations of two or more of the same class and any two of the four above.
The method can also be matched with different simple physical dispersion methods to realize better dispersion fluid and improve the lasting stability of the dispersion fluid.
The method mainly takes a colloid stability theory as a main part, and takes other simple dispersion methods as auxiliary parts. By combining the main and auxiliary methods, the problems that the original fluid system is easy to gelate, precipitate, delaminate and the like in the standing process are effectively solved.
The fluid obtained by the method is a thermodynamic stable system, the unstable components on the surface of particles in the original fluid can be effectively reduced by adding the dispersing agent, the energy of the system is reduced, and the lasting stability of the system is further achieved.
The inorganic small molecular electrolyte comprises inorganic acids, inorganic bases, various inorganic salts and the like. The organic small molecule electrolyte comprises small molecule organic acids, small molecule organic alkalis (organic amines, quaternary ammonium salts) and amphoteric organic molecules (amino acids and the like). The polymer electrolyte comprises polyacids, alkaloids and polymer ampholytes.
Wherein the polyelectrolyte comprises polyacids such as polyacrylic acids, polymethacrylic acid, polystyrene sulfonic acid, polyvinyl phosphoric acid, etc.; the polybases include polyethyleneimine, polyvinylamine, and polyvinylpyridine; polymer amphoteric electrolyte: natural nucleic acids and proteins.
Wherein fluid preparation can be achieved by two methods. A two-step process of primary dispersion by adopting a traditional physical method and then continuous dispersion after adding a required stabilizer; a one-step process for dispersing the material to be dispersed together with the desired stabilizer.
According to the requirements of the invention, the technology of adopting the stabilizer can more easily realize the lasting stability of the fluid, can better save time and the loss of physical mechanical dispersion on the basis of keeping the original physical mechanical dispersion, and has the characteristics of simplicity and easy realization.
The invention can be used for the stability of the slurry in the preparation of the positive and negative pole pieces in the battery field, and the battery system applicable to the method is a zinc-manganese battery, a nickel-zinc battery, a nickel-cadmium battery, a silver-zinc battery, a lead-acid battery, a nickel-hydrogen battery, a lithium ion battery, a fuel battery and the like, and is particularly suitable for the lithium ion battery.
The invention mainly takes the dispersion of the binder in the lithium ion secondary battery as an example, and comprises a solvent, binder powder and a stabilizer. The dosage of the adhesive can be adjusted according to the adhesive force required by the actual pole piece manufacturing process.
The adhesive powder comprises polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, SBR glue and other components.
The lithium ion battery is a lithium ion secondary recyclable charge-discharge battery, and the positive active substance of the lithium ion battery can be at least one of lithium cobaltate, lithium manganate, lithium nickelate and ternary materials; the negative active substance can be at least one of carbon, stannous oxide and lithium titanate; the diaphragm can be at least one of polyolefin, non-woven fabrics and coatings.
By adopting the lasting and stable method provided by the invention, the binder solution has better lasting stability.
Drawings
FIG. 1 is a theoretical model of colloidal stabilization.
FIG. 2 is a graph comparing the specific viscosity of slurries as a function of time for the conventional process (example 1) and the process of example 2 of the present invention.
Detailed Description
The following examples are presented to enable those skilled in the art to more fully understand the present invention and are not intended to limit the invention in any way.
Example 1
This example is a blank experiment, except for the preparation of a dispersion of a binder in a conventional lithium ion secondary battery, without adding the stabilizer of the present invention. Only contains solvent and adhesive powder.
The preparation method comprises the following steps:
polyvinylidene fluoride and a solvent (NMP) (mass ratio 15).
Example 2
The method of this example is to add inorganic small molecule electrolyte hydrochloric acid. The solution is prepared by dissolving hydrochloric acid in a solvent in advance, and is added by a one-step method.
The preparation method comprises the following steps:
polyvinylidene fluoride, a solvent (NMP), an inorganic small molecule (hydrochloric acid) solution (NMP) (mass ratio 15.
Evaluation examples: evaluation of slurry durability (Table 1)
Table 1 comparison of example 1 (conventional process) and example 2 (novel process)
Referring to table 1, the stability of the slurries prepared using the method of the present invention is demonstrated over the original 3 to 4 times time period.
Example 3
The method of this example was to add the polymer electrolyte polyacrylic acid. Polyacrylic acid is added in a one-step process by a method of dissolving polyacrylic acid in a solvent in advance to prepare a solution.
The preparation method comprises the following steps:
polyvinylidene fluoride, a solvent (NMP) and a polyacrylic acid solution (NMP) (mass ratio 15.
The properties are shown in figure 2, and it is obvious that the slurry obtained by the new method has better stability, and the viscosity of the system does not change obviously in a long time.
The above description is only two specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (12)
1. A method for improving the lasting stability of a fluid, which is characterized in that a stabilizing agent is added into the fluid, wherein the stabilizing agent comprises one or a mixture of two of inorganic small molecule electrolyte, organic small molecule electrolyte, polymer electrolyte or surfactant.
2. The method of claim 1, wherein the stabilizer is added in an amount of 0 to 50% by mass of the fluid.
3. The method of claim 1, further comprising treating the fluid with a simple physical dispersion method prior to adding the stabilizer.
4. The method of claim 3, wherein the simple physical dispersion method comprises a combination of one or more of physical mechanical agitation, electromagnetic agitation, ultrasonic dispersion methods, or heat preservation.
5. The method according to claim 1, characterized in that the inorganic small molecule electrolyte comprises an inorganic acid, an inorganic base or an inorganic salt.
6. The method of claim 1, wherein the organic small molecule electrolyte comprises a small molecule organic acid, a small molecule organic base, or an organic amphoteric molecule.
7. The method of claim 6, wherein the small molecule organic base comprises an organic amine or a quaternary ammonium salt; the organic amphiphilic molecule comprises an amino acid.
8. The method of claim 1, wherein the polymer electrolyte comprises a polyacid, a polybase, or a polymeric ampholyte.
9. The method of claim 8 wherein said polyacid comprises polyacrylic acid, polymethacrylic acid, polystyrenesulfonic acid, polyvinylsulfonic acid, or polyvinylphosphoric acid; the polybase comprises polyethyleneimine, polyvinylamine or polyvinylpyridine; the polymeric ampholyte comprises a natural nucleic acid or protein.
10. The method of claim 1, wherein the surfactant comprises an anionic surfactant, a cationic surfactant, and a zwitterionic surfactant.
11. Method according to any of the preceding claims, characterized in that the method is applied for permanent stabilization of fluids in different fields.
12. The method of claim 11, wherein the method is applied to the preparation, transportation or storage of the fluid in different fields.
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| CN201410776957.5A CN105789629A (en) | 2014-12-15 | 2014-12-15 | Method for improving lasting stability of fluid |
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| CN201410776957.5A CN105789629A (en) | 2014-12-15 | 2014-12-15 | Method for improving lasting stability of fluid |
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| CN105789629A true CN105789629A (en) | 2016-07-20 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106784845A (en) * | 2016-12-30 | 2017-05-31 | 深圳市豪鹏科技有限公司 | A kind of aqueous inorganic glue and preparation method and application |
| CN109524646A (en) * | 2018-11-07 | 2019-03-26 | 超威电源有限公司 | A kind of high-energy-density zinc-nickel cell positive electrode and high-energy-density zinc-nickel cell |
| CN109546091A (en) * | 2018-11-07 | 2019-03-29 | 超威电源有限公司 | A kind of high-energy-density zinc-nickel cell anode preparation method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1544335A (en) * | 2003-11-14 | 2004-11-10 | 中山大学 | Nanometer titanium dioxide powder dispersion method |
| CN103903675A (en) * | 2012-12-28 | 2014-07-02 | 北京中科纳通科技有限公司 | High-stability conductive slurry and preparation method thereof |
-
2014
- 2014-12-15 CN CN201410776957.5A patent/CN105789629A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1544335A (en) * | 2003-11-14 | 2004-11-10 | 中山大学 | Nanometer titanium dioxide powder dispersion method |
| CN103903675A (en) * | 2012-12-28 | 2014-07-02 | 北京中科纳通科技有限公司 | High-stability conductive slurry and preparation method thereof |
Non-Patent Citations (1)
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| 杨静漪等: "纳米ZrO2水悬浮液稳定性的研究", 《无机材料学报》 * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106784845A (en) * | 2016-12-30 | 2017-05-31 | 深圳市豪鹏科技有限公司 | A kind of aqueous inorganic glue and preparation method and application |
| CN109524646A (en) * | 2018-11-07 | 2019-03-26 | 超威电源有限公司 | A kind of high-energy-density zinc-nickel cell positive electrode and high-energy-density zinc-nickel cell |
| CN109546091A (en) * | 2018-11-07 | 2019-03-29 | 超威电源有限公司 | A kind of high-energy-density zinc-nickel cell anode preparation method |
| CN109524646B (en) * | 2018-11-07 | 2021-10-26 | 超威电源集团有限公司 | High-specific-energy zinc-nickel battery positive electrode material and high-specific-energy zinc-nickel battery |
| CN109546091B (en) * | 2018-11-07 | 2021-10-26 | 超威电源集团有限公司 | Preparation method of high-specific-energy zinc-nickel battery positive electrode |
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