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CN-122029638-A - Adhesive composite material based on hydrogenated nitrile rubber and polycondensates for electrochemical energy storage devices

CN122029638ACN 122029638 ACN122029638 ACN 122029638ACN-122029638-A

Abstract

The invention relates to a binder composite for a binder of an electrode of an electrochemical energy storage device, comprising a) a hydrogenated nitrile rubber, and b) a polycondensate selected from the group consisting of polyamides having a melting point of 140 ℃ to 270 ℃ and polyesters having a melting point of 175 ℃ to 270 ℃, wherein the polycondensate forms domains in the hydrogenated nitrile rubber, wherein the domains have a dimension D50% of less than 3 micrometers within the matrix of the hydrogenated nitrile rubber.

Inventors

  • HOCH MARTIN
  • LU QI
  • Yelena Dostoevsky
  • Malrang Hemstead Van Urk

Assignees

  • 阿朗新科高性能弹性体(常州)有限公司
  • 阿朗新科德国有限责任公司

Dates

Publication Date
20260512
Application Date
20241022
Priority Date
20231026

Claims (13)

  1. 1. An adhesive composite for an adhesive of an electrode of an electrochemical energy storage device, the adhesive composite comprising A) Hydrogenated nitrile rubber, and B) A polycondensate selected from the group consisting of polyamides having a melting point of 140 ℃ to 270 ℃ and polyesters having a melting point of 175 ℃ to 270 ℃, wherein The polycondensate forms domains in the hydrogenated nitrile rubber, wherein the domains have a size D50% below 3 micrometers within the matrix of the hydrogenated nitrile rubber.
  2. 2. The adhesive composite according to claim 1, wherein the hydrogenated nitrile rubber contains acrylate units, wherein the sum of the remaining hydrocarbon-based monomer units is less than 70 wt-%.
  3. 3. Adhesive composite according to any one of claims 1 or 2, wherein the hydrogenated nitrile rubber has a nitrile content of 7 to 55 wt%, such as 15 to 40 wt%, calculated as acrylonitrile and a degree of hydrogenation of less than 1%, measured as RDB.
  4. 4. An adhesive composite according to any one of claims 1 to 3, wherein the content of polycondensates is in the range of 5 to 40 phr, wherein 100 phr refers to the hydrogenated nitrile rubber.
  5. 5. The adhesive composite according to any one of claims 1 to 4, wherein the polyamide is polyamide 6.
  6. 6. The adhesive composite according to any one of claims 1 to 5, wherein the ratio of the viscosity of the HNBR to the polycondensate is between 1.3 and 5.
  7. 7. The adhesive composite of any one of claims 1 to 6, wherein the adhesive composite is present in an electrode coating dispersion containing an electrochemically active material and a conductive carbon material dispersed in an organic solvent.
  8. 8. The adhesive composite of any one of claims 1 to 6, wherein the adhesive composite is present in an electrode coating dispersion containing a solid electrolyte, optionally an electrochemically active material, and optionally a conductive carbon material dispersed in an organic solvent.
  9. 9. Adhesive composite according to any one of claims 1 to 8, wherein the composite is prepared by melt mixing the polycondensate and the hydrogenated nitrile rubber.
  10. 10. The adhesive composite according to any one of claims 1 to 9, wherein the adhesive composite is free of halogenated compounds.
  11. 11. The adhesive composite according to any one of claims 1 to 10, wherein the adhesive composite passes the selective dissolution Molau test.
  12. 12. An electrode for an electrochemical energy storage device, wherein the electrode comprises a binder composite, the binder composite being provided according to any one of claims 1 to 11.
  13. 13. An electrochemical energy storage device, wherein the electrochemical energy storage device comprises an anode and a cathode, the cathode being arranged according to claim 12.

Description

Adhesive composite material based on hydrogenated nitrile rubber and polycondensates for electrochemical energy storage devices The present invention relates to binder composites useful in electrodes of electrochemical energy storage devices such as lithium ion secondary batteries (libs). The invention further relates to an electrode (e.g. cathode) comprising such a composite material and an electrochemical energy storage device comprising the corresponding electrode. Lithium ion secondary batteries have been widely used as power sources for portable devices since the advent of the lithium ion secondary batteries as small, light and large-capacity batteries in 1991. In recent years, there has been a great increase in demand for batteries for use in electric vehicles. The cathode of LiB comprises mainly cathode active material, which accounts for more than 95 wt-% > of all solid materials used therein. The active material of the cathode of a lithium ion battery allows lithium ions to be reversibly intercalated into and deintercalated from this cathode, while allowing the oxidation state of transition metal ions contained in the active material to be changed. The higher the mass fraction of such active material in the cathode, the higher its charge-discharge capacity and subsequently the higher the energy density. Furthermore, the conductive materials used in the cathode and anode are basically various allotropes of high purity carbon, ranging from carbon black to carbon nanotubes to graphene. Since these materials are solid powders, a flexible polymeric binder is required to allow coating on the current collector as a sufficiently stable layer that can be further processed by cutting, dicing and winding with the anodic film to form the desired cell geometry. Since the uniformity of the coating and the uniform distribution of all materials are extremely important for the cell performance, good dispersion of all particles must be ensured. Fluorinated polymers have long been used in order to bind particulate components of LiB electrodes (e.g., cathodes). The most common adhesive types are based on polyvinylidene fluoride (PVDF), which may sometimes contain some other monomer units. Some PVDF grades have very high molecular weights (Mw) to improve binding efficiency. PVDF has low swelling in the battery electrolyte, which is believed to be important for the integrity of the adhesive film in battery use. However, when an active material having a highly active alkaline component on the surface is selected, there is a problem in using PVDF as a binder. This may be the case for nickel-rich active materials, such as those having nickel-cobalt-manganese oxide, and nickel-cobalt-aluminum oxide in their lithiated form. The strongly basic surface may cause dehydrofluorination of the PVDF, which leads to gelation of the polymer. Nitrile rubbers, in particular the more electrochemically stable hydrogenated form of nitrile rubber (HNBR), have proven to be very suitable dispersing aids for all kinds of carbon materials, including carbon-coated active materials such as lithium iron phosphate, i.e. LPF-C. Insufficient dispersion can lead to gelation and agglomeration of the conductive material. Examples of the use of different HNBR grades as dispersing aids can be found in EP 3319151, EP 3348582, KR 20150016852, EP 3358651, JP 6933285, JP 2020194625, KR 20150067049, EP 3355392. Conductive materials are used as an important component in the electrode to enable electricity to be conducted through the electrode. Hydrogenated nitrile rubber is a very suitable polymer dispersing aid to disperse nano-sized carbon materials in organic solvents to produce cathode slurries. The role of HNBR as binder is illustrated in U.S. Pat. No. 5,408,3064, EP 2660980, EP 3240069, EP 3276713, WO 2020/206606, EP 3220461. HNBR may be used as the sole binder or as a co-binder with PVDF. KR 102329520B1 proposes to add small amounts of organic diacids like oxalic acid to reduce gelation while replacing a certain part of the PVDF by HNBR. In the case of LPF-C (carbon coated LFP), PVDF may be combined with HNBR to allow better dispersion of carbon coated small sized LFP-C particles. Gelation of PVDF may still occur because it may release HF. The primary function of HNBR as a binder or co-binder in the cathode slurry is to reduce the viscosity compared to PVDF as a single binder, which is important for an efficient coating step of the slurry on the current collector. The lower viscosity allows for an increase in the solids content of the slurry, which reduces the amount of process solvent to be evaporated and thus may save energy. However, the cause of the viscosity decrease is not fully understood, and one aspect may be the lower molecular weight of HNBR compared to the cell grade of PVDF. The viscosity of the cathode slurry depends on the formulation selected. The active material typically comprises more than 95% of all solid materials. The particle size,