Electrode for a battery cell with a nitrogen-, fluorine- and phosphorus-doped carbon coating

Abstract

In various embodiments, an electrode (1) is provided for a battery cell. This electrode has an electrode body (2) comprising lithium iron phosphate; and a carbon coating (3) arranged on the electrode body (2); the carbon coating (3) being doped with the elements nitrogen (N), fluorine (F), and phosphorus (P). The invention further relates to a battery cell comprising the electrode and to a battery with at least one such battery cell.

Description

[0001] The present invention relates to an electrode for a battery cell with a nitrogen-, fluorine- and / or phosphorus-doped carbon coating.

[0002] After decades as the energy storage of choice for small devices ranging from smartphones and laptops to power drills, lithium-ion batteries are still used in hybrid and fully electric vehicles. The cathode of a lithium-ion battery typically consists of a lithium metal oxide, which may also contain varying amounts of nickel, manganese, and cobalt. The anode is usually made of graphite.

[0003] Due to their superior structural stability, high safety level and low cost, lithium iron phosphate (LiFePO4, abbreviated LFP) and lithium manganese iron phosphate (LiMn) are x Fe 1-xLithium iron phosphate (LFP) is the predominant olivine-type cathode material for lithium-ion batteries. LMFP is considered an improved version of LFP and can be produced by doping lithium iron phosphate with manganese. However, its unrestricted use is limited by its poorer electronic conductivity and slow diffusion kinetics.

[0004] German patent application DE 10 2021 114 084 A1 discloses a negative electrode and an electrochemical cell. The negative electrode and the electrochemical cell contain a protective layer to prevent and inhibit the growth of lithium dendrites on the negative electrode and their growth into a separator. The protective layer comprises a first layer and a second layer. The first layer contains a first polymeric binder and an optional insulating material. The second layer contains a dendrite-consuming material and a second polymeric binder. The second layer further comprises an electrically conductive material selected from the group consisting of carbon black, super-P-carbon black, acetylene carbon black, graphite, carbon nanotubes, carbon fibers, graphene, graphene oxide, vapor-deposited carbon fibers, nitrogen-doped carbon, a metallic powder, a liquid metal, and combinations thereof.

[0005] Publication DE 10 2021 130 558 A1 discloses a lithium metal electrode of a battery cell, which may in particular be made of lithium iron phosphate, wherein a ceramic layer is arranged on the surface of the lithium metal electrode or is embedded in the surface.

[0006] Publication CN 106129358 A discloses a process for the synthesis of a porous, nitrogen-doped graphene carbon film coated with lithium iron phosphate and used as a cathode material for a battery cell.

[0007] The object of the present invention can be seen as providing a cathode material for lithium-ion batteries in which the problem mentioned above is eliminated or at least reduced.

[0008] This problem is solved by means of the subject matter of the independent claims. Further preferred embodiments are found in the dependent claims.

[0009] According to the invention, an electrode for a battery cell is provided, comprising an electrode body containing lithium iron phosphate and a carbon coating arranged on the electrode body. The carbon coating is doped with the elements nitrogen, fluorine, and phosphorus.

[0010] The invention relates to a carbon-coated nanocomposite material based on LFP. Using such a cathode in a lithium-ion battery can significantly improve its electrochemical performance. In a further embodiment, LMFP of the olivine type can also be used instead of LFP.

[0011] By providing a conductive carbon coating co-doped with nitrogen, fluorine, and phosphorus (i.e., coexisting with all of these substances within the carbon coating), preferably in a three-dimensional porous structure, the conductivity and ion diffusion rate of LFP and LMFP can be improved. The maximum performance and long-term stability of LFP and LMFP below -20 °C at high current density are enhanced, ultimately extending the lifespan of the corresponding battery cell.

[0012] The N-, F-, and P-codoped carbon coating on the surface of LFP or LMFP creates a highly conductive three-dimensional network structure, even at low temperatures, enabling rapid electron transport and fast reaction kinetics between the intercrystals. Furthermore, the LFP or LMFP provided with an N-, F-, and P-codoped carbon coating according to the invention can exhibit a three-dimensional porous structure, which also improves the accessibility of Li+ over a longer cycle. This provides a sustainable and economical incentive for modifying the cathode material of lithium-ion batteries according to the present invention.

[0013] The electrode according to the invention can be integrated into existing processes in standard Li-ion cells, in next generation Li-ion cells (Li-Ion advanced chemistry), in Li-ion cells with Li anode, and in LFP semi-solid-state cells.

[0014] According to further embodiments of the electrode according to the invention, the electrode body can consist of lithium iron phosphate.

[0015] According to further embodiments of the electrode according to the invention, the lithium iron phosphate can be doped with manganese. Accordingly, the electrode body material can comprise LMFP.

[0016] According to further embodiments of the electrode according to the invention, the carbon coating can be formed as a three-dimensional porous structure.

[0017] According to further embodiments of the electrode according to the invention, the electrode body with the doped carbon coating can form a composite material.

[0018] According to the invention, a battery cell is further provided, comprising at least a first electrode, a second electrode and an electrolyte arranged between the electrodes, wherein the first electrode comprises an electrode according to one of the embodiments described above.

[0019] According to further embodiments of the battery cell according to the invention, the first electrode can be a cathode.

[0020] According to further embodiments of the battery cell according to the invention, the second electrode can be selected from at least one material from the list consisting of graphite, silicon-carbon composite and lithium.

[0021] According to the invention, a battery is further provided, comprising at least one battery cell according to one of the embodiments described above.

[0022] The features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0023] Further advantages and embodiments of the invention will become apparent from the following description of exemplary embodiments and the accompanying drawing.

[0024] Fig. Figure 1 shows an embodiment of an electrode 1 according to the invention for a battery cell. This electrode has an electrode body 2 which comprises lithium iron phosphate. A carbon coating 3, doped with the elements nitrogen (N), fluorine (F) and phosphorus (P), is arranged on and around the electrode body 2. 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 2021 114 084 A1

[0004] DE 10 2021 130 558 A1

[0005] CN 106129358 A

[0006]

Claims

[1] Electrode (1) for a battery cell, comprising: an electrode body (2) comprising lithium iron phosphate; and a carbon coating (3) which is arranged on the electrode body (2); wherein the carbon coating (3) is doped with the elements nitrogen (N), fluorine (F) and phosphorus (P). [2] Electrode (1) according to claim 1, wherein the electrode body (2) consists of lithium iron phosphate. [3] Electrode (1) according to claim 1 or 2, wherein the lithium iron phosphate is doped with manganese. [4] Electrode (1) according to any one of claims 1 to 3, wherein the carbon coating (3) forms a three-dimensional porous structure. [5] Electrode (1) according to any one of claims 1 to 4, wherein the electrode body (2) forms a composite material with the doped carbon coating (3). [6] Battery cell comprising: at least one first electrode and one second electrode, and an electrolyte arranged between the electrodes, wherein the first electrode comprises an electrode (1) according to one of the preceding claims. [7] Battery cell according to claim 6, wherein the first electrode is a cathode. [8] Battery cell according to claim 6 or 7, wherein the second electrode comprises at least one material selected from the list consisting of graphite, silicon-carbon composite and lithium. [9] Battery comprising at least one battery cell according to any one of claims 6 to 8.

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