Cathode of a battery cell of a traction battery, traction battery of a motor vehicle and motor vehicle

Abstract

Cathode (13) of a traction battery of a motor vehicle, comprising crystalline iron(II) fluoride (FeF2) particles having a diameter between 25 nm and 45 nm, wherein the crystalline iron(II) fluoride (FeF2) particles are at least partially surrounded by a carbon-containing shell having a thickness between 1 nm and 6 nm.

Description

[0001] The invention relates to a cathode of a battery cell of a traction battery, a traction battery of a motor vehicle and a motor vehicle with at least one traction battery.

[0002] The structure of a vehicle traction battery is well known. A traction battery comprises several battery cells. These cells are either directly housed within the battery casing or within battery module housings of traction battery modules positioned inside the casing. The main components of a traction battery cell are an anode, a cathode, an electrolyte, and a separator. In a solid-state battery, the electrolyte is a solid electrolyte and typically also serves as the separator. A vehicle traction battery is a rechargeable battery.

[0003] DE 10 2023 113 358 A1 discloses a cathode composition of a cathode of a lithium-ion battery, wherein the cathode composition comprises a particulate bellows cathode active material which includes a coating on one surface thereof. The coating is a metal fluoride, a lithium metal fluoride, or both a metal fluoride and a lithium metal fluoride.

[0004] US 2018 / 0219214A1 discloses another cathode for a lithium battery. The cathode features active material particles formed as metal fluorides or metal chlorides, with a size between 0.4 nm and 10 µm.

[0005] US 2023 / 0 253 563 A1 and US 2015 / 0 155 546 A1 reveal further state of the art.

[0006] There is a need to provide a high-performance traction battery for a motor vehicle with a long service life, enabling a large number of discharge and charge cycles at high power. The object of the invention is to provide a cathode of a battery cell of such a traction battery, such a traction battery of a motor vehicle, and a motor vehicle with at least one such traction battery. This object is achieved by a cathode according to claim 1, a traction battery according to claim 10, and a motor vehicle according to claim 12.

[0007] According to the invention, the cathode comprises crystalline iron(II) fluoride (FeF2) particles having a diameter between 25 nm and 45 nm, wherein the crystalline iron(II) fluoride (FeF2) particles are at least partially surrounded by a carbon-containing shell with a thickness between 1 nm and 6 nm. It is a surprising finding of the invention that a traction battery whose cathode comprises crystalline iron(II) fluoride (FeF2) particles at least partially surrounded by a carbon-containing shell, wherein the iron(II) fluoride (FeF2) particles have a diameter between 25 nm and 45 nm, and wherein the carbon-containing shell of the crystalline iron(II) fluoride (FeF2) particles has a thickness between 1 nm and 6 nm, can ensure a large number of discharge and charge cycles of the traction battery while guaranteeing high performance.A surprising finding of the invention is that the cathode according to the invention exhibits improved lithiation and delithiation behavior, as well as improved conductivity and capacitance. As a result of discharge and charge cycles, a cathode-electrolyte interface layer forms on the cathode during operation, with a thickness between 2 nm and 8 nm. Iron(III) fluoride can form in this cathode-electrolyte interface layer, providing additional capacitance. The cathode material beneath the cathode-electrolyte interface layer retains its original nanostructure and iron(II) fluoride properties.

[0008] Preferably, the crystalline iron(II) fluoride (FeF2) particles of the cathode have a diameter between 30 nm and 40 nm, wherein the carbonaceous shell of the crystalline iron(II) fluoride (FeF2) particles of the cathode preferably has a thickness between 2 nm and 5 nm. This serves to further increase the performance of a traction battery comprising the cathode by providing a large number of charge and discharge cycles.

[0009] Preferably, the carbon-containing shell of the crystalline iron(II) fluoride (FeF2) particles of the cathode contains nitrogen and / or hydrogen. This also serves to further increase the performance of a traction battery comprising the cathode by providing a large number of discharge and charge cycles of the traction battery.

[0010] Preferably, the carbon-containing shell comprises pyridine (C5H5N). In particular, the carbon-containing shell consists of pyridine (C5H5N). When the shell comprises or consists of pyridine, the performance of a traction battery comprising the cathode according to the invention can be further increased, particularly by enabling a large number of discharge and charge cycles of the traction battery.

[0011] The crystalline iron(II) fluoride (FeF2) particles form a core body of the cathode, which consists exclusively of these crystalline iron(II) fluoride (FeF2) particles. The crystalline iron(II) fluoride (FeF2) particles of the core body are at least partially coated with the common carbonaceous shell.

[0012] Preferably, the anode of each battery cell of the traction battery is designed as a lithium anode or lithium-based anode. A surprising finding of the invention is that the cathode according to the invention, in combination with a lithium anode or lithium-based anode, enables a large number of charge and discharge cycles at high traction battery performance.

[0013] Preferred embodiments of the invention are described in the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being limited thereto. The drawing shows: Fig. 1. A schematic view of a motor vehicle with a traction battery, Fig. 2 A schematic view of a battery cell of the traction battery of the motor vehicle.

[0014] Fig. Figure 1 shows a motor vehicle 10 with a traction battery 11. The traction battery 11 is a rechargeable battery and has several battery cells 12, wherein Fig. Figure 2 shows a highly schematic representation of the structure of a battery cell 12.

[0015] The battery cell 12 has a first electrode serving as cathode 13, a second electrode serving as an anode 14, and an electrolyte 15 arranged between the electrodes.

[0016] In Fig. 2 The electrolyte 15 is a solid electrolyte, which also serves as a separator 16. Fig. Figure 2 further shows an electrical connection 17 of the cathode 13 and an electrical connection 18 of the anode 14. Although in Fig. 2 where the battery cell 12 of a solid-state battery is shown, the electrolyte 15 of which is therefore designed as a solid-state electrolyte, the invention is not limited to solid-state batteries.

[0017] As already explained, each battery cell 12 has a cathode 13. According to the invention, the cathode 13 of each battery cell 12 comprises crystalline iron(II) fluoride (FeF2) particles. The iron(II) fluoride (FeF2) particles have a diameter between 25 nm and 45 nm, preferably a diameter between 30 nm and 40 nm.

[0018] The crystalline iron(II) fluoride (FeF2) particles are at least partially surrounded by a carbon-containing shell, wherein the carbon-containing shell has a thickness between 1 nm and 6 nm, preferably a thickness between 2 nm and 5 nm.

[0019] The crystalline iron(II) fluoride (FeF2) particles form a base body of the cathode 13, wherein the base body of the cathode 13 consists exclusively of the crystalline iron(II) fluoride (FeF2) particles and is at least partially coated with the carbon-containing shell.

[0020] All iron(II) fluoride (FeF2) particles forming the base body of the cathode 13 are therefore at least partially surrounded by the common, carbon-containing shell or at least partially coated with it.

[0021] Such a cathode 13, when used in a traction battery 11, enables a large number of charge and discharge cycles at high power output. Surprisingly, the cathode 13 according to the invention exhibits significantly improved lithiation and delithiation behavior compared to conventional cathodes. The cathode 13 according to the invention is protected against chemical and electrochemical damage. During operation, a cathode-electrolyte interface layer, only 2 nm to 8 nm thick, forms between the cathode 13 and the electrolyte 15 as a result of the charge and discharge cycles. The material of the cathode 13 beneath this interface layer remains unchanged, thus retaining its nanostructure with the properties of crystalline iron(II) fluoride (FeF₂). The cathode-electrolyte interface layer provides additional capacity.

[0022] The carbon-containing shell, which at least partially surrounds the crystalline iron(II) fluoride (FeF₂) particles, contains at least carbon, and preferably also nitrogen and / or hydrogen. The nitrogen content of the carbon-containing shell can preferably be between 1.5 wt.% and 5 wt.%.

[0023] The carbon-containing shell, which at least partially surrounds the base body of the crystalline iron(II) fluoride (FeF2) particles, particularly preferably has pyridine C5H5N or consists of pyridine C5H5N.

[0024] The carbon in the carbon-containing shell is preferably amorphous. Carbon bonds of the carbon in the shell at least partially surrounding the iron(II) fluoride (FeF2) particles are preferably conjugated.

[0025] The invention further relates to a traction battery 11, the battery cells 12 of which each have a cathode 13 according to the invention.

[0026] Preferably, the battery cells 12 have an anode 14, which is configured as a lithium-metal anode or a lithium-based metal anode. A surprising finding of the invention is that the cathode 13 according to the invention, in combination with a lithium-metal anode or a lithium-based metal anode, ensures a particularly high performance of a traction battery 11 and enables a large number of charge and discharge cycles. The cathode and anode, in combination, improve the specific capacity and capacity retention of the traction battery 11.

[0027] The invention enables the provision of traction batteries 11 that exhibit high performance over a large number of charge and discharge cycles. This increases the service life of a traction battery 11. High performance of the traction battery 11 can be ensured both during charging and discharging. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2023 113 358 A1

[0003] US 2018 / 0 219 214 A1

[0004] US 2023 / 0 253 563 A1

[0005] US 2015 / 0 155 546 A1

[0005]

Claims

[1] Cathode (13) of a battery cell (12) of a traction battery (11) of a motor vehicle (10), with crystalline iron(II) fluoride (FeF2) particles having a diameter between 25 nm and 45 nm, wherein the crystalline iron(II) fluoride (FeF2) particles are at least partially surrounded by a carbon-containing shell with a thickness between 1 nm and 6 nm. [2] Cathode (13) according to claim 1, characterized by , that the crystalline iron(II) fluoride (FeF2) particles have a diameter between 30 nm and 40 nm. [3] Cathode (13) according to claim 1 or 2, characterized by , that the carbon-containing shell has a thickness between 2 nm and 5 nm. [4] Cathode (13) according to any one of claims 1 to 3, characterized by , that the carbon in the carbonaceous shell is amorphous. [5] Cathode (13) according to any one of claims 1 to 4, characterized by that the carbon-containing shell also contains nitrogen. [6] Cathode (13) according to any one of claims 1 to 5, characterized by that the carbon-containing shell also contains hydrogen. [7] Cathode (13) according to any one of claims 1 to 6, characterized by , that the carbon-containing shell contains pyridine (C5H5N). [8] Cathode (13) according to any one of claims 1 to 7, characterized by , that the carbon-containing shell consists of pyridine (C5H5N). [9] Cathode (13) according to any one of claims 1 to 8, characterized by , that the crystalline iron(II) fluoride (FeF2) particles form a base body of the cathode (13), wherein the base body of the cathode (13) consists exclusively of the crystalline iron(II) fluoride (FeF2) particles and is coated at least partially with the carbon-containing shell. [10] Traction battery (11) of a motor vehicle (10), with multiple battery cells (12), wherein each battery cell (12) has a first electrode serving as a cathode (13), a second electrode serving as an anode (14) and an electrolyte (15), characterized by , that the cathode (13) of the respective battery cell (12) is designed according to one of claims 1 to 9. [11] Traction battery (11) according to claim 10, characterized by , that the anode (14) of the respective battery cell (12) is designed as a lithium anode or lithium-based anode. [12] Motor vehicle (10) with at least one traction battery (11) according to claim 10 or 11.

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