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DE-102024133130-A1 - High silicon anode and its production, as well as traction battery and motor vehicle with such an anode

DE102024133130A1DE 102024133130 A1DE102024133130 A1DE 102024133130A1DE-102024133130-A1

Abstract

High silicon anode for a lithium-ion traction battery, characterized by the following features: - the high silicon anode comprises a copper foil (10) and an active material (11) electrically connected to the copper foil (10) and - the active material (11) has an auxetic structure.

Inventors

  • Rebecca Valerie Feser
  • Ilona Jipa

Assignees

  • DR. ING. H.C. F. PORSCHE AKTIENGESELLSCHAFT

Dates

Publication Date
20260513
Application Date
20241113

Claims (10)

  1. High silicon anode for a lithium-ion traction battery, characterized by the following features: - the high silicon anode comprises a copper foil (10) and an active material (11) electrically connected to the copper foil (10) and - the active material (11) has an auxetic structure.
  2. High silicon anode according to Claim 1 , characterized by the following feature: - the active material (11) contains carbon.
  3. High silicon anode according to Claim 2 , characterized by one of the following features: - the carbon is crystalline or - the carbon is amorphous.
  4. High silicon anode according to one of the Claims 1 until 3 , characterized by the following feature: - the active material (11) contains molecular nanotubes.
  5. High silicon anode according to Claim 4 , characterized by the following feature: - the nanotubes possess the auxetic structure.
  6. High silicon anode according to one of the Claims 1 until 5 , characterized by one of the following features: - the structure is two-dimensional or - the structure is three-dimensional.
  7. High silicon anode according to one of the Claims 1 until 6 , characterized by one of the following features: - the structure is metallic, - the structure is organometallic or - the structure is polymeric.
  8. Lithium-ion traction battery, characterized by the following feature: - the traction battery has a high silicon anode after one of the Claims 1 until 7 on.
  9. motor vehicle with a traction battery according to Claim 8 .
  10. Production of a high-silicon anode according to one of the Claims 1 until 7 , characterized by the following features: - the active material (11) is mixed with an auxetic material, either wet or dry, to form a slurry and - the copper foil (10) is coated with the slurry.

Description

The present invention relates to a high-silicon anode for a traction battery. The present invention further relates to a corresponding traction battery, a corresponding motor vehicle, and a corresponding manufacturing process. State of the art Lithium-ion batteries have become the preferred energy storage devices in electric vehicles due to their high energy density, long lifespan, and good performance. The negative electrode (anode) is traditionally made of graphite, a carbon-based material that absorbs lithium ions through intercalation. However, to further increase energy density, silicon is increasingly being considered as an anode material because it has a significantly higher theoretical capacity than graphite. Silicon can hold up to 3.75 lithium ions per silicon atom, resulting in a theoretical specific capacity of approximately 3579 mAh/g. However, this high lithium capacity is accompanied by significant volume changes. During the lithiation process, the volume of silicon can increase by up to 300%. These volumetric expansions and contractions during charge and discharge cycles lead to mechanical stresses that can cause cracking, pulverization, and loss of electrical contact in the anode material. This significantly impacts the battery's cycle life and represents one of the major challenges in integrating silicon as an anode material. To address this problem, various approaches have been developed. One commonly pursued method is the use of nanostructured silicon, such as nanoparticles, nanowires, or thin films, to minimize the effects of volume changes. Furthermore, silicon-carbon composites are employed, in which silicon is embedded in a carbon-based matrix to maintain structural integrity and ensure electrical conductivity. Binders with improved elastic properties, as well as specialized coatings, have also been investigated to increase the mechanical stability of the anode. Furthermore, hybrid materials have been developed in which silicon is combined with other components to improve mechanical properties. For example, the integration of conductive polymers, metal-organic frameworks (MOFs), and various carbon modifications such as graphene or carbon nanotubes (CNTs) has been explored. These materials, due to their low electrical resistance, function as a conductive network within the anode. Such materials can contribute to making the anode material flexible and reducing mechanical stress. So-called auxetic materials are characterized by a negative Poisson ratio (NPR), meaning they expand under tensile stress in the transverse direction and contract under compressive stress in the transverse direction. This unusual property can be used to develop materials that better withstand mechanical stresses and counteract cracking. US20140315093A1 This describes a battery with a negative electrode containing a framework with auxetic structures exhibiting a negative Poisson coefficient. The framework consists of intermediate struts running between adjacent grids, each containing the auxetic structures. At the core of the struts, a thin layer of copper is deposited onto the framework elements, and a conformal layer of amorphous silicon is sputtered over the copper as the electroactive material. CN116565206A This describes a secondary battery with a silicon-based cathode material whose negative Poisson ratio is intended to improve the stability of the core-shell structure. The cathode current collector consists of aluminum or copper foil. Through the interaction of the silicon with the electrolyte, a compact SEI film is formed, which limits the volume of the silicon and thus improves the structural stability of the cathode material during the charging and discharging process. DE102013224751A1 This describes a battery cell in which the porous collector of one electrode consists of a metallic foam such as copper. This collector can be used for either the positive or negative electrode. The pores of the collector are coated. This auxetic porous collector can be combined with an auxetic separator or inlet film. The swelling of the electrode during charging is absorbed by the auxetic collector, which extends the lifespan of the battery cell. Furthermore, the collector can be used with solid-state electrolytes. CN220491947U Describes a battery with an anode plate and an external structure with an elliptical negative Poisson ratio. Its adjustable Stiffness and metastructure increased damping effects, improved fracture resistance and protected the internal structure of the battery from damage, thus increasing its lifespan. DE102014225069A1 This describes a porous battery cell module made of an auxetic material characterized by a negative Poisson's ratio. The auxetic behavior of the component is intended to distribute the stress forces occurring within the module evenly across the entire cross-section of the battery cell. This increases the lifespan of the battery cells. Furthermore, the material offers higher mechanic