Traction battery of a motor vehicle and motor vehicle

Abstract

A traction battery (11) of a motor vehicle, comprising a plurality of battery cells (12), each battery cell (12) comprising a first electrode (13) serving as a cathode, a second electrode (14) serving as an anode, an electrolyte (15) arranged between the electrodes (13, 14), and a separator (17) likewise arranged between the electrodes (13, 14), the electrolyte (15) being a mixture of triethyl phosphate (TEP) and fluoroethylene carbonate (FEC) comprising between 20 vol.% and 40 vol.% triethyl phosphate (TEP) and between 60 vol.% and 80 vol.% fluoroethylene carbonate (FEC), lithium hexafluorophosphate (LiPF6) being dissolved in the mixture of triethyl phosphate (TEP) and fluoroethylene carbonate (FEC) at a molar concentration M of between 1 g / mol and 2 g / mol.

Description

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

[0002] The structure of a motor vehicle's traction battery is well known. A traction battery comprises several battery cells. The battery cells are arranged either directly in a battery housing of the traction battery or indirectly in battery module housings of battery modules of the traction battery, which are positioned within the battery housing.

[0003] The main components of a traction battery cell are an anode, a cathode, an electrolyte, and a separator. The electrolyte and separator are located between the anode and cathode.

[0004] In a motor vehicle's traction battery, thermal runaway, which can lead to the battery burning out, must be prevented. Therefore, there is a need for a traction battery with a reduced risk of thermal runaway.

[0005] US 2024 / 0 021 804 A1 shows the basic structure of a battery cell with an anode, a cathode, an electrolyte and a separator.

[0006] EP 2 677 591 B1 discloses a secondary battery.

[0007] SANGSANIT, Thitiphum, et al. Non-flammable electrolyte for large scale Ni-rich Li-ion batteries: Reducing thermal runaway risks. Journal of Power Sources, 2024, vol. 594, p. 234021 discloses a non-flammable electrolyte with the composition 1.2 M LiPF6 TEP:FEC = 70:30 v / v. The same is disclosed in Supporting Information, SANGSANIT, Thitiphum, et al. Non-flammable electrolyte for large scale Ni-rich Li-ion batteries: Reducing thermal runaway risks. Journal of Power Sources, 2024, vol. 594, p. 234021.

[0008] JP 2015- 097 179 A discloses further prior art.

[0009] The object of the invention is to create a novel traction battery of a motor vehicle and a motor vehicle with at least one such traction battery.

[0010] This object is achieved by a traction battery according to patent claim 1 and a motor vehicle according to patent claim 9.

[0011] According to the invention, the electrolyte comprises a mixture of TEP (triethyl phosphate) and FEC (fluoroethylene carbonate) comprising between 20 vol.% and 40 vol.% TEP and between 80 vol.% and 60 vol.% TEP, wherein LiPF6 (lithium hexafluorophosphate) is dissolved in the mixture at a molar concentration M of between 1 g / mol and 2 g / mol.

[0012] In the traction battery of a motor vehicle according to the invention, a novel electrolyte is used in the battery cells. This electrolyte comprises a mixture of TEP and FEC in a defined mixing ratio, with LiPF6 dissolved in this mixture of TEP and FEC at a defined molar concentration M. With such an electrolyte, the risk of thermal runaway and thus the thermal failure of a battery cell and thus of the traction battery can be reduced. During operation, a LiF (lithium fluoride) coating can form on the electrodes, which can counteract the decomposition of the electrolyte during longer charging cycles of the traction battery. This can ensure a longer battery life with consistent battery performance.

[0013] Preferably, the mixture comprises between 25 vol% and 35 vol% TEP (triethyl phosphate) and between 75 vol% and 65 vol% FEC (fluoroethylene carbonate), in particular between 28 vol% and 32 vol% TEP (triethyl phosphate) and between 72 vol% and 68 vol% FEC (fluoroethylene carbonate). Such a mixture of TEP and FEC in the electrolyte is particularly preferred.

[0014] Preferably, LiPF6 (lithium hexafluorophosphate) is dissolved in the mixture of TEP (triethyl phosphate) and FEC (fluoroethylene carbonate) at a molar concentration M of between 1 g / mol and 1.5 g / mol, in particular at a molar concentration M of between 1.1 g / mol and 1.3 g / mol. Such a molar concentration M of LiPF6 in the mixture of TEP and FEC is particularly preferred.

[0015] Preferred developments of the invention emerge from the subclaims and the following description.

[0016] Exemplary embodiments of the invention are explained in more detail with reference to the drawings, without being limited thereto. Fig. 1 is 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.

[0017] Fig. 1 shows a motor vehicle 10 with a traction battery 11. The traction battery 11 is a rechargeable battery having several battery cells 12, wherein Fig. 2 shows a highly schematic view of the structure of a battery cell 12.

[0018] The main components of a battery cell 12 are a first electrode 13 serving as a cathode, a second electrode 14 serving as an anode, an electrolyte 15 arranged between the electrodes 13, 14 and a separator 16 also arranged between the electrodes 13, 14. Fig. 1 a battery cell housing 17.

[0019] According to the invention, the electrolyte 15 is a mixture of TEP (triethyl phosphate) and FEC (fluoroethylene carbonate) containing between 20 vol.% and 40 vol.% TEP and between 60 vol.% and 80 vol.% FEC.

[0020] In particular, the mixture of the electrolyte of TEP and FEC comprises 25 vol.% and 35 vol.% TEP and between 65 vol.% and 75 vol.% FEC, particularly preferably between 28 vol.% and 32 vol.% TEP and between 68 vol.% and 72 vol.% FEC.

[0021] LiPF6 is dissolved in the mixture of TEP and FEC at a molar concentration M of between 1 g / mol and 2 g / mol.

[0022] In particular, the molar concentration is between 1 g / mol and 1.5 g / mol, particularly preferably between 1.1 g / mol and 1.3 g / mol.

[0023] In a particularly preferred embodiment, the electrolyte 15 consists of a mixture with 30 vol.% TEP and 70 vol.% FEC, wherein LiPF6 is dissolved in this mixture in a molar concentration M of 1.2 g / mol.

[0024] By using such an electrolyte 15 in a battery cell 12 of a traction battery 11 of a motor vehicle, the risk of thermal runaway and thus thermal failure of the respective battery cell 12 and thus of the entire traction battery 11 can be reduced, so that the risk of a battery cell 15 catching fire is reduced.

[0025] A further advantage is that a robust solid electrolyte interface made of LiF forms on the electrodes 13 and 14 during operation. This counteracts electrolyte decomposition during long charging cycles. This can increase battery life while maintaining battery performance.

[0026] The cathode 13 of the respective battery cell 12 is preferably a nickel-based cathode.

[0027] The anode 14 of the respective battery cell 12 is preferably a silicon-based and / or graphite-based anode.

Claims

[1] Traction battery (11) of a motor vehicle (10), with several battery cells (12), wherein each of the battery cells (12) has a first electrode (13) serving as a cathode, a second electrode (14) serving as an anode, a an electrolyte (15) arranged between the electrodes (13, 14) and a separator (17) also arranged between the electrodes (13, 14), characterized by , that the electrolyte (15) is a mixture of triethyl phosphate (TEP) and fluoroethylene carbonate (FEC) comprising between 20 vol.% and 40 vol.% triethyl phosphate (TEP) and between 60 vol.% and 80 vol.% fluoroethylene carbonate (FEC), wherein lithium hexafluorophosphate (LiPF6) is dissolved in the mixture of triethyl phosphate (TEP) and fluoroethylene carbonate (FEC) at a molar concentration M of between 1 g / mol and 2 g / mol. [2] Traction battery (11) according to claim 1, characterized bythat the mixture of triethyl phosphate (TEP) and fluoroethylene carbonate (FEC) contains between 25 vol% and 35 vol% triethyl phosphate (TEP) and between 65 vol% and 75 vol% fluoroethylene carbonate (FEC). [3] Traction battery (11) according to claim 1 or 2, characterized by that the mixture of triethyl phosphate (TEP) and fluoroethylene carbonate (FEC) contains between 28 vol% and 32 vol% triethyl phosphate (TEP) and between 68 vol% and 72 vol% fluoroethylene carbonate (FEC). [4] Traction battery (11) according to claim 1, 2 or 3, characterized by that the mixture of triethyl phosphate (TEP) and fluoroethylene carbonate (FEC) contains 30 vol% triethyl phosphate (TEP) and 70 vol% fluoroethylene carbonate (FEC). [5] Traction battery (11) according to one of claims 1 to 4, characterized by that lithium hexafluorophosphate (LiPF6) is dissolved in the mixture at a molar concentration M of between 1 g / mol and 1.5 g / mol. [6] Traction battery (11) according to one of claims 1 to 5, characterized by that lithium hexafluorophosphate (LiPF6) is dissolved in the mixture at a molar concentration M of between 1.1 g / mol and 1.3 g / mol. [7] Traction battery (11) according to one of claims 1 to 6, characterized by that lithium hexafluorophosphate (LiPF6) is dissolved in the mixture at a molar concentration M of 1.2 g / mol [8] Traction battery (11) according to one of claims 1 to 7, characterized by , that the cathode is a nickel-based cathode, the anode is a silicon-based and / or graphite-based anode. [9] Motor vehicle (10) with at least one traction battery (11) according to one of claims 1 to 8.

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