High viscosity processing powdered polymer binder for anode manufacturing

Abstract

A composition comprising a non-spherical powdery crosslinked polymer obtained by grinding, the crosslinked polymer comprising the monomer units 1,3 butadiene, (hydroxyethyl) methacrylate and trimethylolpropane trimethacrylate, the non-spherical powdery crosslinked polymer having a particle size D(90) of 180 to 450 μm. The composition further comprises a silica caking inhibitor. The composition is used as a binder in the anode of a storage battery.

Description

[Technical field]

[0001] The present invention describes a composition as a binder for the anode of a storage battery. The composition comprises a non-spherical powdery crosslinked polymer obtained by grinding. The crosslinked polymer comprises the monomer units 1,3 butadiene, (hydroxyethyl) methacrylate (HEMA) and trimethylolpropane trimethacrylate (TMPTMA), and the non-spherical powdery crosslinked polymer has a particle size D(90) of 180 to 450 μm, and the composition further comprises a silica anti-caking agent. [Background technology]

[0002] A battery (also known as a storage battery, secondary cell or accumulator) is a type of battery that can be charged, discharged and recharged many times. Batteries play an important role in bringing about a greener and more sustainable future.

[0003] The battery includes an anode, a cathode, an electrolyte solution, and a separator. A binder is also present in the battery, usually a rubbery polymer. The binder holds the active and conductive materials together, which are then cast onto the electrode current collector.

[0004] Binders play an important role in the performance of batteries. First, they facilitate the dispersion of the other components (e.g., active material, conductive material) in the liquid during casting on the current collector (some also act as thickeners), allowing for uniform dispersion. Second, the binder holds the various components of the battery, such as the active material and conductive material, and the current collector together, ensuring good contact by chemical or physical interactions; the binder binds these separate components and keeps them together, ensuring the mechanical integrity of the electrode during charging and discharging without substantially affecting the electronic or ionic conductivity. Third, the binder acts as an interface between the current collector and the electrolyte, thus protecting the current collector from corrosion.

[0005] The binder needs to have the following properties: flexibility, insolubility in the electrolyte, good adhesion to the current collector, chemical and electrochemical stability, and ease of attachment to the current collector.

[0006] To achieve the above mentioned properties, the problem-free casting of the binder and, for example, the active material and the conductive material onto the current collector of the electrode depends not only on the binder itself but also on the casting method.

[0007] Patent Document 1 discloses a powdery composition comprising a polymer consisting of the monomer units acrylonitrile, 1,3-butadiene and trimethylolpropane trimethacrylate (TMPTMA). The powdery composition comprises a silica anticaking agent. The powdery composition has an average particle size in the range of 0.01-4 mm. The powdery composition is used in the manufacture of tire treads, which simultaneously improves wet skid resistance, dry grip and rolling resistance and provides good mixing properties. Patent Document 1 does not disclose a polymer comprising the monomer unit (hydroxyethyl) methacrylate (HEMA).

[0008] US Patent No. 5,399,663 discloses a microgel polymer comprising the monomeric units acrylonitrile, 1,3-butadiene, (hydroxyethyl) methacrylate (HEMA) and trimethylolpropane trimethacrylate (TMPTMA). The polymer is post-processed by spray drying to obtain spherical or substantially spherical microgel particle agglomerates having an average particle size of 2-500 μm. The microgel polymer is an additive that can be easily incorporated into thermosetting compositions such as plastics to improve impact strength and energy absorption up to the breaking point while maintaining qualities such as mechanical strength, glass transition temperature and modulus of elasticity.

[0009] J.-H. Lee et al. (Non-Patent Document 1) discloses a conventional casting method for the anode surface using a mixture of emulsified styrene butadiene rubber (SBR) polymer and sodium carboxymethyl cellulose (CMC) as the anode binder. This paper by J.-H. Lee et al. discloses precasting of a binder mixture with a relatively low solids weight fraction of 35%. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] European Patent Application Publication No. 3902855A1 [Patent Document 2] European Patent Application Publication No. 3053938A [Non-patent literature]

[0011] [Non-Patent Document 1] Journal of Power Sources 147(2005)249-255 Summary of the Invention [Problem to be solved by the invention]

[0012] There is a need to provide improved binder compositions, uses of the binder compositions for anodes in batteries, and processes for making the anodes. [Means for solving the problem]

[0013] In a first aspect, the present invention relates to a composition comprising a non-spherical powdered crosslinked polymer obtained by grinding, the crosslinked polymer comprising the monomer units 1,3 butadiene, (hydroxyethyl) methacrylate (HEMA) and trimethylolpropane trimethacrylate (TMPTMA), the non-spherical powdered crosslinked polymer having a particle size D(90) of 180-450 μm, and the composition further comprising a silica anti-caking agent.

[0014] In a further aspect, the present invention relates to the use of the composition as described above as a binder for the anode of a storage battery.

[0015] In a further aspect, the present invention relates to a binder composition for an anode of a storage battery. The binder composition for the anode comprises a composition comprising a non-spherical powdered crosslinked polymer obtained by grinding. The crosslinked polymer comprises the monomer units 1,3 butadiene, (hydroxyethyl) methacrylate (HEMA) and trimethylolpropane trimethacrylate (TMPTMA), and the non-spherical powdered crosslinked polymer has a particle size D(90) of 180 to 450 μm, and the composition further comprises a silica anti-caking agent. The binder composition also comprises a conductive material. The binder composition also comprises an active material.

[0016] In a further aspect, the present invention relates to a process for producing an anode. The process comprises providing an extruder with a composition comprising a non-spherical powdered crosslinked polymer obtained by grinding. The crosslinked polymer comprises the monomer units 1,3 butadiene, (hydroxyethyl) methacrylate (HEMA) and trimethylolpropane trimethacrylate (TMPTMA), and the non-spherical powdered crosslinked polymer has a particle size D(90) of 180 to 450 μm, and the composition further comprises a silica anti-caking agent. The process also comprises providing an active material and a conductive material to the extruder, and then laminating the obtained extrudate on the surface of an anode current collector.

[0017] In contrast to spherical particles, when milled particles are provided, it has been found that non-spherical shapes are more suitable for application on the anode as a binder, since their irregular shape captures and holds the active and conductive materials. This is in contrast to the use of spray-dried particles according to the prior art, which causes slippage of the active and conductive materials, resulting in a non-uniformly agglomerated blend of the binder, active and conductive materials, which causes agglomeration points of the binder, active and conductive materials, which causes poor adhesion to the current collector and poor quality of the coated current collector. There is a better distribution of the active and conductive materials and the binder polymer. The particles according to the present invention have been developed to exhibit high shear resistance for extrusion-based processing.

[0018] The powders according to the invention are free flowing, facilitating casting of current collectors at high solids. This is in contrast to prior art coating methods using latex solvent systems, where the first coating is usually of poor quality, necessitating repeated coating in later steps to build up layers, thus necessitating batch coating. The present invention eliminates the need for relatively high solvent content when casting onto current collectors.

[0019] This process for making anodes facilitates the processing of high solids slurries and granules for the production of anodes. The process allows for continuous production of anodes with high throughput, reduced time (e.g., solvent drying time, multiple coating steps with solvent-based coatings), and reduced energy compared to prior art batch manufacturing. The extruded polymer exits the extruder as a paste, is hot, and in liquid or paste-like form, and is applied directly to the current collector surface.

[0020] This process allows for processing of at least 70% by weight solids compared to traditional solvent-based processing methods. The use of high solids slurries with little solvent reduces drying times for the coated electrodes. [Brief description of the drawings]

[0021] [Figure 1] The difference between a) the polymer obtained by spray drying and b) the polymer obtained by grinding is shown. [Diagram 2] FIG. 2a shows a coated current collector according to the prior art and FIG. 2b according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] In order to obtain a fuller understanding of the present invention and its advantages, the following detailed description is presented.

[0023] It will be appreciated that the various aspects and embodiments of the detailed description disclosed herein are illustrative of specific ways to make and use the invention, and are not intended to limit the scope of the invention in view of the claims and detailed description. It will also be appreciated that features from different aspects and embodiments of the invention may be combined with features from different aspects and embodiments of the invention.

[0024] In a first aspect, the present invention relates to a composition comprising a non-spherical powdered crosslinked polymer obtained by grinding, the crosslinked polymer comprising the monomer units 1,3 butadiene, (hydroxyethyl) methacrylate (HEMA) and trimethylolpropane trimethacrylate (TMPTMA), and the non-spherical powdered crosslinked polymer has a particle size D(90) of 180 to 450 μm, the composition further comprising a silica anti-caking agent.

[0025] It should be recognized that the non-spherical powdered crosslinked polymer is a rubber.

[0026] For the avoidance of doubt, the non-spherical powdered crosslinked polymer is not hydrogenated.

[0027] The term powdered means dry particles produced by grinding of the polymer. The term dry indicates a moisture content of ≦1% by weight.

[0028] The term non-spherical means that the powdered polymer does not resemble a sphere of round shape, i.e. is not substantially a geometric object in three-dimensional space like the surface of a ball. It is known in the art that polymers obtained by grinding are non-spherical compared to polymers obtained by spray drying during post-processing procedures. Figure 1 shows the difference between a) polymers obtained by spray drying and b) polymers obtained by grinding, in particular, Figure 1a) shows a polymer powder obtained by spray drying, which has a sphere-like shape and is round in shape, i.e. is substantially a geometric object in three-dimensional space like the surface of a ball, and in contrast, Figure 1b) shows a polymer powder obtained by grinding, which has a rough outer surface.

[0029] Grinding of the crosslinked polymers is accomplished using grinding equipment and grinding processes known in the art, such as cryogenic grinding, wet grinding, mechanical grinding, or ball mill grinding processes, for such rubber-based crosslinked polymers.

[0030] By "comminuter" is meant any device capable of generating sufficient shear and / or crushing forces to break the material being comminuted into smaller fragments, including hammer mills, such as disintegrators and pin mills, disc mills, fluidized bed air jet mills, jaw crushers, gyratory crushers, cage mills, pan crushers, ball, pebble rod and tube mills, disc attrition mills, attritors, disc refiners, and the like.

[0031] The grinding device is therefore fitted with sieves known in the art to obtain a particle size D(90) of 50-900 μm, preferably 100-600 μm and most preferably 180-450 μm.

[0032] The composition comprises a silica anticaking agent. The anticaking agent refers to an additive that is mixed with the non-spherical powdered crosslinked polymer obtained by grinding. The anticaking agent prevents the formation of agglomerates (caking, clumping) of the non-spherical powdered crosslinked polymer obtained by grinding. The anticaking agent facilitates packaging, transportation and maintains the flowability of the non-spherical powdered crosslinked polymer obtained by grinding.

[0033] The silica anti-caking agent is present in an amount of 3 to 15% by weight based on the non-spherical powdered crosslinked polymer.

[0034] The term monomeric unit means that a structural unit derived from that monomer is included in the polymer obtained using that monomer.

[0035] The monomer units include 1,3 butadiene, trimethylolpropane trimethacrylate (TMPTMA) and (hydroxyethyl) methacrylate (HEMA).

[0036] The 1,3 butadiene is present in an amount of 99-32.5% by weight, preferably 97.5-45% by weight. The trimethylolpropane trimethacrylate (TMPTMA) is present in an amount of 0.5-7.5% by weight, preferably 1-6% by weight. The (hydroxyethyl)methacrylate (HEMA) is present in an amount of 0.5-10% by weight, preferably 2.5-9% by weight.

[0037] The particle size D(90) of the non-spherical powdered crosslinked polymer can be determined using a laser diffuser. Samples were prepared using the Fraunhofer approximation to determine the particle size distribution with a calculated refractive index and absorption coefficient of "1". From the volume histogram, D90 was obtained as the output of the analysis. D90 indicates the diameter at which 90 percent of the distribution of the non-spherical powdered crosslinked polymer has a smaller particle size and 10 percent has a larger particle size.

[0038] The crosslinked polymer may further comprise the monomer unit acrylonitrile, which is present in an amount up to 50% by weight, preferably up to 40% by weight.

[0039] In a further aspect, the present invention relates to the use of the composition as a binder for an anode of a storage battery.

[0040] In a further aspect, the present invention relates to an electrode composition for an anode of a storage battery. The electrode composition for the anode comprises a composition comprising as a binder a non-spherical powdered crosslinked polymer obtained by grinding. The crosslinked polymer comprises the monomer units 1,3 butadiene, (hydroxyethyl) methacrylate (HEMA) and trimethylolpropane trimethacrylate (TMPTMA), and the non-spherical powdered crosslinked polymer has a particle size D(90) of 180 to 450 μm, and the binder further comprises a silica caking inhibitor. The electrode composition also comprises a conductive material. The electrode composition also comprises an active material.

[0041] The active material can be a carbon material, such as amorphous carbon, natural graphite, artificial graphite, natural graphite, mesocarbon microbeads, pitch-based carbon fibers, and silicon-graphite. The active material can be a conductive polymer, such as polyacene or polyaniline. The active material can be a metal, such as silicon, tin, zinc, manganese, iron, and nickel, or alloys thereof, or oxides thereof, and sulfates thereof. The active material can be at least one of the above or any combination thereof.

[0042] The conductive material can be a carbon-based material, such as carbon black (e.g., acetylene black, furnace black), graphite, graphene, carbon fibers (carbon nanofibers, carbon nanotubes, and vapor-grown carbon fibers), and carbon flakes. The conductive material can be at least one of the foregoing or any combination thereof.

[0043] The active material is present in an amount of 85 to 99.9% by weight of the electrode composition, more preferably 90 to 99.75% by weight.

[0044] The conductive material is present in an amount of 0.5 to 20% by weight of the electrode composition, more preferably 1 to 10% by weight.

[0045] In a further aspect, the present invention relates to a process for producing an anode. The process comprises providing an extruder with a composition comprising a non-spherical powdered crosslinked polymer obtained by grinding. The crosslinked polymer comprises the monomer units 1,3 butadiene, (hydroxyethyl) methacrylate (HEMA) and trimethylolpropane trimethacrylate (TMPTMA), and the non-spherical powdered crosslinked polymer has a particle size D(90) of 180 to 450 μm, and the composition further comprises a silica anti-caking agent. The process also comprises providing an active material and a conductive material to the extruder, and then laminating the obtained extrudate on the surface of an anode current collector.

[0046] The extruder can include a single screw extruder or a multi-screw extruder, which can include any number and type of barrel and screw elements, as well as other single or multi-screw conveyor kneaders.

[0047] The multi-screw extruder can be a twin-screw extruder, a ring extruder or a planetary roller extruder, with twin-screw extruders and ring extruders being preferred. Twin-screw extruders are, for example, counter-intermeshing, counter-intermeshing, co-rotating intermeshing and co-rotating non-intermeshing twin-screw extruders, with co-rotating intermeshing twin-screw extruders being preferred.

[0048] Suitable extruder elements of the extruder include not only the extruder screw, but also the kneading section, which includes the kneader element for the energy input and mixing of the composition. Examples of kneading elements include kneading blocks that can be designed as front, rear or intermediate conveyor kneading blocks with double or triple flights; grooved screw mixing elements with single or double flights, tooth-type mixing elements with single flights, blister plates and eccentric plates with single, double or triple flights. The kneader elements can be assembled in any combination on the shaft of the extruder, in particular the shaft of a twin screw counter-rotating or co-rotating twin screw extruder.

[0049] Further extruder elements in the form of extruder screws and / or kneaders can be provided downstream of the die plate or gear pump and upstream of the outlet. In particular, several conveying and / or degassing stages can be provided, each stage preferably being optimized to the expected parameters, in particular the number of volatile compounds to be removed from the extrudate that is expected.

[0050] The extruder has at least one, and preferably two or more, feed zones. The composition is added as an aqueous paste such that the total solids content of the materials added to the extruder is at least 70% by weight.

[0051] The die plate of the extruder contains at least one, and preferably a plurality of perforation openings, which may have any shape, for example, the perforation openings may have a funnel or cone shape, a convergent or divergent nozzle shape, an hourglass shape, a channel shape, a circular or non-circular shape.

[0052] The extruder is capable of either heating or cooling through the barrel to temperatures up to 300° C. In a preferred embodiment, the extruder includes means for operating separate zones at different temperatures independently so that the zones can be either heated, unheated or cooled.

[0053] The extruder is operated at a feed rate of 0.1 to 25000 kilograms / hour, or preferably at a feed rate of 0.25 to 6000 kilograms / hour.

[0054] The conductive material and the active material can be first premixed and then mixed with a composition comprising a non-spherical powdery crosslinked polymer obtained by grinding, the non-spherical powdery crosslinked polymer comprising the monomer units 1,3 butadiene, (hydroxyethyl) methacrylate (HEMA) and trimethylolpropane trimethacrylate (TMPTMA) and having a particle size D(90) of 180 to 450 μm, and a silica anti-caking agent before being added to the extruder.

[0055] It is preferred that all ingredients are added to the extruder and therefore mixed in the extruder as this has been found to ensure the most uniform extrudate, however, premixing of the ingredients may be done prior to addition to the extruder.

[0056] The anode current collector is an electrically conductive, electrochemically durable material that does not undergo or cause chemical changes in the fabricated battery. The anode current collector may be made of iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, or platinum. The current collector may be in the form of a foil or mesh.

[0057] The anode current collector typically has a thickness in the range of 2 to 500 μm.The invention and its advantages are illustrated by the following non-limiting examples. EXAMPLES

[0058] material The following materials were used as provided:

[0059] The monomer units acrylonitrile, trimethylolpropane trimethacrylate (TMPTMA) and (hydroxyethyl)methacrylate (HEMA) from Sigma-Aldrich, and 1,3-butadiene from INEOS.

[0060] Solution Fe(II)SO 4 The premix solution contains 0.986 g of Fe(II)SO 4 *7H 2 O and 2.0 g of Rongalit® C in 400 g of water.

[0061] EDTA: as a complexing agent from Sigma-Aldrich.

[0062] Fatty acids: CAS 67701-08-6, emulsifier for polymerization.

[0063] Rosin acid: disproportionated rosin acid sodium salt CAS 61790-51-0, emulsifier for polymerization.

[0064] AOS: Alpha Olefin Sulfonate CAS 68439-57-6, emulsifier for polymerization.

[0065] t-DDM: Molecular weight regulator manufactured by Arlanxeo Deutschland GmbH.

[0066] Trigonox® NT50, p-menthane hydroperoxide from Akzo-Degussa. Initiator for emulsion polymerization.

[0067] Diethylhydroxylamine: Polymerization terminator, CAS 3710-84-7.

[0068] Antioxidant: equal mixture of Irganox® 1520 - 2-methyl-4,6-bis(octylsulfamylmethyl)phenol (BASF AG, Germany), Irganox® 1076 - n-octadecyl-β-(4-hydroxy-3,5-di-tert-butyl-phenyl)-propionate (BASF AG, Germany) and Wingstay® L - poly(dicyclopentadiene-co-p-cresol) (Omnova, Italy).

[0069] Lithium-nickel-cobalt-manganese-oxide: active material; manufactured by BASF (6 / 2 / 2 type).

[0070] Conductive Carbon Black: Conductive agent; Super C65 manufactured by TIMCAL Company.

[0071] Conductive graphite, conductive material, SFG 6L from Imerys.

[0072] Polyvinylidene fluoride (PVDF): cathode binder, Solef 5130 from Solvay.

[0073] Aluminum foil: cathode current collector; thickness 20 μm; 1085 alloy made from Hydro Aluminum

[0074] N-Methylpyrrolidone (NMP): Solvent; CAS 872-50-4 from BASF.

[0075] Polyethylene ceramic film: as separator, thickness 28 μm (Separion, 28 μm), manufactured by Litarion

[0076] EC / EMC (3:7), 2% by volume of vinyl chloride (VC), and 1M lithium hexafluorophosphate (LiPF 6 ) and electrolyte, LP57 manufactured by Gotion Inc.

[0077] Artificial graphite, anode active material, CAS 7782-42-5.

[0078] CMC, anode binder, PA Walocel 2000 from Dow.

[0079] SBR latex polymer for anode binder, CAS 9010-93-9. Comparative Example.

[0080] Copper foil, anode current collector, thickness 8μm, electrolytic copper foil NC-WS made by Sumitomo.

[0081] Polytetrafluoroethylene (PTFE) glass cloth foil, release foil manufactured by Hightechflon Films And Fabrics.

[0082] Adhesive tape, tesafix 5696 extra strong from Tesa.

[0083] A method for producing a crosslinked polymer containing the monomer units 1,3 butadiene (and also acrylonitrile), (hydroxyethyl) methacrylate (HEMA) and trimethylolpropane trimethacrylate (TMPTMA) There is also described a method for producing Comparative Example C according to EP 3902855 A1, which contains the monomer units acrylonitrile, 1,3-butadiene and trimethylolpropane trimethacrylate (TMPTMA), i.e. no (hydroxyethyl)methacrylate (HEMA).

[0084] A method for producing Comparative Example D according to EP 3053938A is also described, which comprises the monomer units acrylonitrile, 1,3-butadiene, (hydroxyethyl) methacrylate (HEMA) and trimethylolpropane trimethacrylate (TMPTMA), the polymer being post-treated by spray drying to obtain spherical or substantially spherical microgel particle agglomerates.

[0085] For the preparation of each crosslinked polymer, the ingredients according to Table 1 were used. In the case of monomer increments, the amount of monomer and the addition time according to the particular conversion are given in brackets.

[0086] [Table 1]

[0087] Each polymer was prepared batchwise in a 5 L autoclave equipped with a stirring system. Each autoclave batch used 1.25 kg monomer mixture, 2.1 kg total water, and Fe(II)SO 4An equimolar amount of EDTA was used based on the Fe(II) from the above. The amount of 1.9 kg of water was initially charged into the autoclave along with the emulsifiers (fatty acid and acid) and purged with a stream of nitrogen. t-DDM was added and the reactor was closed. After the contents reached the polymerization temperature, the solution Fe(II)SO 4 The polymerization was initiated by adding the premix solution and Trigonox® NT50. The polymerization was monitored by gravimetric measurement of the conversion. After reaching the indicated conversion, the polymerization was stopped by adding a 25% aqueous solution of diethylhydroxylamine polymerization terminator.

[0088] Unconverted monomer units (ie, unpolymerized) and remaining volatiles were removed by steam distillation.

[0089] A 50% dispersion of the antioxidant was mixed with the dispersion of the polymer latex.

[0090] Post-treatment of cross-linked polymers The various latexes were post-treated by either Route 1 or Route 2 as shown in Table 2.

[0091] [Table 2]

[0092] Route 1: The latex was coagulated with either calcium chloride or aluminum sulfate. The latex was coagulated with calcium chloride at pH 6 (adjusted with acetic acid or HCl) and dried in a vacuum oven for 16 hours to obtain the respective crosslinked polymer. Alternatively, the latex was coagulated with aluminum sulfate at pH 8 (adjusted with acetic acid or HCl) and dried in a vacuum oven for 16 hours to obtain the crosslinked polymer.

[0093] The preparation of the non-spherical powdered crosslinked polymer was carried out as follows: The crosslinked polymer was mixed with the specified amount of anticaking agent (see Table 3) in a beaker and the mixture was slowly added to a RETSCH ZM 200 Ultra Centrifugal Mill to grind the crosslinked polymer. The RETSCH ZM 200 Ultra Centrifugal Mill was fitted with an annular sieve with an average mesh size of 0.25 mm and operated at speeds of 10000-18000 rpm to obtain different particle sizes. During grinding, the mill was cooled with liquid nitrogen. After grinding, the non-spherical powdered crosslinked polymer was removed from the grinding chamber by a cyclone and collected. The resulting non-spherical powdered crosslinked polymer was dried at 55°C for 24 hours.

[0094] Route 2: Water was removed from the latex by spray drying from the polymer to obtain the polymer in the form of a fine powder. The anticaking agent for separation was added as a dry powder into the spray tower.

[0095] Table 3 shows various properties of the polymers based on post-treatment procedures, anti-caking agents and agglomeration tendency after grinding.

[0096] The agglomeration tendency of the powders was graded by visual assessment and rated based on the following criteria for each sample powder: 1 (sample is not agglomerated and is free flowing), 2 (sample shows slight agglomeration, the agglomerates break up under low pressure or on their own) and 3 (sample shows slight agglomeration, sticks to each other, the agglomerates break up under gentle pressure).

[0097] As can be seen from Table 3, samples containing silica as an anti-caking agent are non-agglomerated and free-flowing, therefore such samples are most useful for continuous extrusion processes capable of handling high solids with continuous binder addition.

[0098] Please note that the examples / samples marked with * are in accordance with the findings of the present invention.

[0099] The liquid coagulation state in Table 3 refers to latex, and sample 1 uses SBR rubber, which is styrene-butadiene or styrene-butadiene rubber (SBR).

[0100] [Table 3]

[0101] Manufacturing of anodes by extrusion and calendaring process Samples 1 to 7 were used for the preparation of each anode.

[0102] Samples 8-11 exhibited agglomeration and were deemed unsuitable due to non-uniform dispersion of the conductive and active materials in the blend with the polymer (binder) during extrusion, which would cause further agglomeration in the extruder.

[0103] For the preparation of the anode the following was used: 93% by weight of active material (graphite), 1.4% by weight of carbon black, 1.87% by weight of CMC and 3.73% by weight of mass percentages of the different types of samples (from 1 to 7).

[0104] A water dispersion thereof was made having a solids content of 76.5% by weight.

[0105] The aqueous dispersion was continuously fed into a twin-screw extruder (Rheomex PTW16 / 40 OS, Thermo Fisher Scientific, 16 mm screw diameter) with a rotation speed of 700 rpm and a throughput of 800 g / h to obtain a high-viscosity anode electrode paste.

[0106] The high viscosity anode electrode paste exits the extruder through a 3 mm circular nozzle and is captured by a strand granulator (hot die cutting HAAKE PolyLab OS, Thermo Fisher Scientific) and divided into 1 mm granules.

[0107] The granules are placed in the gap of a calendar and pressed to a final coating thickness of 100 μm while simultaneously laminating the coating onto the copper substrate. During the coating step, the surface of the calendar roll is covered with a release film and the calendar roll is operated at a constant gap width of 165 μm and a line speed of 0.2 m / min. After coating, the 0.75 W / cm 2 The continuous drying is carried out in an IR radiation field with an intensity of 1.3 g / cm. The electrode density of the anode is 1.3 g / cm. 3 It is.

[0108] Binder adhesion to current collector and coating uniformity The adhesion strength of the coated electrodes to the substrate with regard to adhesive and cohesive failure is investigated in a uniaxial testing machine (Z020, Zwick GmbH & Co.KG). Two coplanar plates are placed in the testing machine, which are covered with a double-sided adhesive tape (tesafix 5696 extra strong, Tesa). A circular electrode punch with a diameter of 12 mm is placed between the plates. The electrode sample is now compressed with a force of 68 N with a dwell time of 30 seconds. The testing machine is then pulled away from the contacted sample and the maximum tensile force is detected. The adhesion strength is calculated by the following formula:

number

[0109] To determine the adhesive strength of each electrode, ten measurements are taken and then averaged.

[0110] The coating uniformity (surface coverage, roughness, uniformity) was graded for each anode by visual assessment based on the following criteria: 1 (electrode shows no defects and has the best surface quality), 2 (electrode shows minor defects and surface roughness and has partial delamination from the current collector) and 3 (electrode cannot be produced for use, shows numerous defects or up to complete delamination).

[0111] The adhesive strength of the anode to the current collector and the uniformity of the coating were examined, and the results are shown in Table 4.

[0112] [Table 4]

[0113] As can be seen from the results in Table 4. The current collectors cast with the prior art polymers (spherical polymer particles, samples 1 and 2) show poor quality coated electrodes. This is further illustrated in FIG. 2, which is shown in FIG. 2a, where the coating is very poor and uneven on the current collector. Furthermore, samples 1 and 2 have poor adhesive strength. This is due to the fact that these samples are obtained by spray drying. Samples 1 and 2, which are apparently latex-based anode binders, cannot be used for extrusion-based electrode processing, while the powdered samples of the present invention show good processability and high adhesive strength.

[0114] Additionally, sample 6, which does not contain the monomer unit (hydroxyethyl)methacrylate (HEMA), exhibits poor coating quality and relatively poor adhesive strength, thus demonstrating the effectiveness of the (hydroxyethyl)methacrylate (HEMA) monomer unit according to the present invention.

[0115] Sample 7, which was spray dried and used calcium carbonate anti-caking agent, showed very poor coating quality and no measurable adhesive strength whatsoever.

[0116] Samples 3 to 5 according to the invention were shown to be the best non-spherical powder cross-linked polymers obtained by grinding and therefore best suited for use as polymer binders. These polymers showed very high adhesive strength and the quality of the anodes is shown in Figure 2b. As is evident from Figure 2b, the electrodes have no defects and the best surface quality.

[0117] Possible applications in batteries To analyze the compositions according to the invention as binders for the anodes of electrodes, cathodes for storage batteries were prepared.

[0118] A reference cathode binder of 93.00 wt% NCM 622, 2.00 wt% Super C65, 1.00 wt% SFG6L and 4.00 wt% PVDF polymer was produced by the following process steps: All powdered raw materials were homogenized simultaneously in a tumbler mixer for 15 minutes. PVDF is pre-dissolved in NMP and all components are mixed in a 10 L planetary mixer with a dispersion time of 60 minutes. The solid content of the NMP-based dispersion is 75 wt%. This suspension was then coated by a doctor blade onto an aluminum current collector foil (Hydro Aluminium) and dried by three separate continuous convection (80°C / 100°C / 120°C in 2 m long drying sections, respectively) to obtain a 23.3 mg / cm2 solids. 2 (about 3.6mAh / cm 2 ) to achieve a target mass coating amount of 3.0 g / cm2. 3 The mixture was calendered to a density of 0.01g / g.

[0119] To analyze the electrochemical properties, a pouch full cell with a single layer configuration was fabricated (anode, ≈30 cm 2 ; Cathode, ≒ 25cm 2 (four cells for each parameter) and electrochemical cycling was performed (Maccor Inc.). The electrodes were post-vacuum dried at 120 °C for 16 h under argon atmosphere. Further components of the pouch cells were a ceramic separator and EC / EMC (3:7) with 2 vol.% vinyl chloride (VC) and 1 M lithium hexafluorophosphate (LiPF 6 ) and electrolyte. After formation is complete (3 cycles at 0.1C), the cycling regime of the cell is C-rate test (charge / discharge at 0.2C / 0.2C, 0.5C / 0.5C, 1C / 1C, 2C / 2C, 3C / 3C for each of the 3 cycles) followed by long-term cycling (0.5C / 0.5C). The discharge regime is based on CC step (constant current) and the charge regime is based on CCCV step (constant current constant voltage), which is terminated when the charge current drops below 0.05C. The overall cell voltage is operated at 3.0-4.2V and the discharge depth is always 100%.

[0120] The discharge specific capacity of the battery was formed after three formation steps at a charge / discharge rate of 0.1 C. The capacity retention was determined as the ratio of the discharge specific capacity after 75 cycles to the discharge specific capacity at a charge / discharge rate of 0.5 C.

[0121] The specific discharge capacity and capacity retention of cells containing the polymers according to the invention were measured and the results are shown in Table 5.

[0122] [Table 5]

[0123] Although the discharge specific capacity and capacity retention could not be measured for latex-based sample 1, the electrode using the powdered binder of the present invention can achieve good battery performance.

[0124] Having described the invention and its advantages, it is to be understood that the various aspects and embodiments of the invention disclosed herein are merely illustrative of specific ways to make and use the invention.

[0125] The various aspects and embodiments of the present invention do not limit the scope of the invention in light of the appended claims and the above detailed description.

[0126] What is desired to be protected by Letters Patent is set forth in the following claims.

Claims

1. - A non-spherical powdered crosslinked polymer obtained by grinding, comprising monomer units of 1,3-butadiene, (hydroxyethyl) methacrylate and trimethylolpropane trimethacrylate, and having a particle size D (90) of 180 to 450 μm, - Silica solidification inhibitor and A composition containing the following:

2. The composition according to claim 1, wherein the crosslinked polymer further comprises monomer units of acrylonitrile.

3. The composition according to claim 1 or 2, wherein the crosslinked polymer comprises the following amounts of monomer units, 1,3-butadiene in the range of 99 to 32.5% by weight, (hydroxyethyl) methacrylate in the range of 0.5 to 10% by weight, trimethylolpropane trimethacrylate in the range of 0.5 to 7.5% by weight, and acrylonitrile in the range of 0 to 50% by weight.

4. The composition according to claim 1, wherein the silica solidification inhibitor is present in an amount of 3 to 15% by weight relative to the crosslinked polymer.

5. Use of the composition according to claim 1 as a binder for the anode of a storage battery.

6. An electrode composition for the anode of a storage battery, - The composition described in claim 1, - Active material and, - Conductive materials and An electrode composition containing the following:

7. The electrode composition according to claim 6, wherein the active material is selected from at least one of a carbon material, a conductive polymer, a metal or an alloy thereof, or a salt thereof, or a sulfate thereof, or any combination thereof.

8. The electrode composition according to claim 6, wherein the conductive material is a carbon-based material.

9. A process for manufacturing an anode, - To provide the composition described in claim 1 to an extruder, - To provide the active material and conductive material to the extruder, - The obtained extruded material is laminated onto the surface of the anode current collector. A process that includes this.

10. The process according to claim 9, wherein the total solid content of the composition, active material and conductive material according to claim 1 is at least 70% by weight.

11. The process according to claim 9, wherein the anode current collector comprises a metal selected from iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, or platinum.

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