Fabrication of liquid organic electrolyte metal-ion battery components and electrochemical cells incorporating said components

Abstract

The subject of the present invention is a method for producing such components, the components obtainable by said method, and the use of these components in the manufacture of liquid organic electrolyte electrochemical cells.

Description

[Technical Field]

[0001] The present invention relates to the technical field of metal-ion battery components (cathode, anode or separator) obtained by direct extrusion in the form of a film or formed by melt deposition from composite filaments or granules. The present invention more particularly relates to a method for producing such components, components that may be obtained by said method and the use of these components in the manufacture of electrochemical cells with liquid organic electrolytes. [Background technology]

[0002] Metal-ion (lithium or sodium) batteries with liquid organic electrolytes are a key technology for many applications (mobile devices, automotive, stationary, aerospace, etc.) and are sold on a large scale, encouraging researchers to continuously improve their performance and develop sustainable and environmentally friendly manufacturing processes.

[0003] Additive manufacturing (usually abbreviated as FA), especially fused filament fabrication (internationally abbreviated as FFF for "fused filament fabrication" or FGF for "fused granular fabrication"), is gaining attention due to its design flexibility and solvent-free manufacturing capabilities. Using this technology, also known as a 3D printing process, it is possible, on the one hand, to produce three-dimensional battery structures with a high active surface, which increases the theoretical specific capacity at high cycle rates. On the other hand, this technology also allows the battery to perfectly adapt to the shape of the final object, thereby maximizing the energy storage capacity.

[0004] 3D printing of batteries requires the production of filaments or composite granules corresponding to the different components: separator, positive electrode, and negative electrode. These composite filaments or granules typically contain a thermoplastic polymer matrix to which different materials, such as electrochemically active materials, electrically conductive components, ceramic nanoparticles, plasticizers, etc., are added depending on their intended role.

[0005] After the 3D printing or assembly stage, the battery electrodes and separators must be able to be impregnated with liquid electrolyte while maintaining their mechanical integrity. However, to date, for components comprising a single polar thermoplastic polymer (WO 2016 / 036607): - The liquid electrolyte cannot penetrate into the center of the electrode printed with FFF: in this case, only the active material on the surface of the electrode is accessible to the electrolyte, which makes the electrochemical reaction partial and difficult, resulting in significant polarization in the electrochemical curve and very low capacity; - Or the polymer was impregnated with electrolyte but lost its mechanical integrity after a few cycles, resulting in poor battery performance.

[0006] Furthermore, the electrodes of WO 2016 / 036607 contain up to 50% by weight, typically 10% to 30% by weight, of electrochemically active material relative to the weight of the polymer. Furthermore, WO 2019 / 202600 also teaches the production of electrodes with a single functional polymer by additive manufacturing, in which conductive carbon (50-70% by weight) and an electrochemically active material are dispersed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2016 / 036607 [Patent Document 2] International Publication No. 2019 / 202600 Summary of the Invention [Problem to be solved by the invention]

[0008] The methods taught in international applications WO 2016 / 036607 and WO 2019 / 202600 have the disadvantage of providing electrodes with an insufficient mass content of electrochemically active material (less than 50%), or electrodes with poor mechanical strength, or electrodes with insufficient electrolyte wettability. [Means for solving the problem]

[0009] More particularly, to overcome the above-mentioned drawbacks, applicant has disclosed a method for producing composite filaments, films, or granules for fabricating liquid organic electrolyte metal-ion battery components, the method comprising: a. providing or preparing at least two thermoplastic polymer compositions; a first non-polar polymer composition comprising at least one first non-polar thermoplastic polymer, said first non-polar thermoplastic polymer having a melting temperature Tf1 and being incompatible with a liquid organic electrolyte intended to be incorporated into said metal-ion battery; and a second polar polymer composition comprising at least one polar thermoplastic polymer, the polar thermoplastic polymer having a melting temperature Tf2 and having an affinity with the liquid organic electrolyte, the non-polar thermoplastic polymer and the first polar thermoplastic polymer being immiscible; b. mixing the at least first and second non-polar and polar polymer compositions to form a thermoplastic polymer mixture; c. introducing the composite composition into an extruder and then extruding to form composite granules, composite filaments, or composite films; the extrusion step is carried out at a temperature Te equal to or greater than the melting temperature of the thermoplastic polymer blend, preferably 10° C. higher than the melting temperature of the thermoplastic polymer blend, Therefore, a method has been developed, which includes the steps of: (a) forming a composite granule, a composite film, or a composite filament at the end of the extrusion process, the composite granule, the composite film, or the composite filament, which is composed of a polymer matrix having a bicontinuous morphology of the polar thermoplastic polymer and the first non-polar thermoplastic polymer, ensuring electrochemical functionality and mechanical strength.

[0010] The term "polymer derived from a given monomer" means, within the meaning of the present invention, both homopolymers derived from said single monomer and copolymers derived from said given monomer and at least one other different monomer.

[0011] The term "co-continuous morphology" refers within the meaning of the present invention to a polymer matrix comprising a mixture of immiscible polymers, each polymer forming a continuous network within the matrix.

[0012] With regard to step c), if the thermoplastic polymer mixture obtained in step b) contains only the first thermoplastic polymer composition and the second thermoplastic polymer composition (without any plasticizer-type additives), the melting temperature of the thermoplastic polymer mixture corresponds to the highest temperature between Tf1 and Tf2. If a plasticizer is present, the melting temperature of the thermoplastic polymer mixture may be lower than Tf2.

[0013] Among the plasticizers that can be used within the scope of the present invention, mention may in particular be made of plasticizers of the ATBC (acetyl tributyl citrate) and PC (propylene carbonate) type.

[0014] The first non-polar polymer composition includes a first non-polar thermoplastic polymer that can ensure the mechanical stability of the component during battery operation. The first non-polar thermoplastic polymer is inert to the electrolyte. If necessary (when the component is an electrode), the first polymer composition can include an active material and a carbon filler, thus functioning as a host structure and ensuring the mechanical strength of the electrode.

[0015] Among the first non-polar thermoplastic polymers that can be used within the scope of the present invention, mention may be made in particular of olefins and their mixtures, preferably polypropylene (PP) or polyethylene (PE).

[0016] The first non-polar polymer composition may also contain a second non-polar thermoplastic polymer selected from saturated (e.g., olefin-based copolymers) or unsaturated (e.g., polystyrene or SBR) elastic non-polar polymers and / or mixtures thereof. Polypropylene-based elastomers (PBE) are preferably used as the second non-polar polymer. This second non-polar polymer is inert to the electrolyte while imparting high flexibility to the resulting final part (which may be in the form of a filament, preferably a spoolable filament).

[0017] The second polar polymer composition comprises a polar thermoplastic polymer that has an affinity with the electrolyte and facilitates impregnation of the battery components and diffusion of lithium ions within the structure.

[0018] Polar polymers that can be used within the scope of the present invention include, in particular, esters such as polycaprolactone (PCL), ethers such as PEO (polyethylene oxide), carbonates, polyamides, polycaprolactone (PCL), and PVDF (polyvinylidene fluoride).

[0019] According to a first embodiment of the method according to the invention, the first and second polymer compositions can be dissolved. In this case, the first non-polar polymer composition further comprises a non-polar solvent, and the second polar composition further comprises a polar solvent. Step b) of mixing the first and second non-polar and polar polymer compositions can then be carried out, advantageously at the highest temperature of the two solutions after the polar and non-polar polymers are completely dissolved in their respective solvents, for a duration comprised between 1 minute and 30 minutes. The non-polar and polar thermoplastic polymers are pre-dissolved in their respective solvents, advantageously for a period comprised between 30 minutes and 24 hours. In a particular case of this embodiment, the method according to the invention further comprises, between the mixing step b) and the extrusion step c), a step b') of spreading the composite composition on a flat surface to form a composite film, followed by a drying step b''), which is then cut into pieces in a cutting step b''') for insertion into the extruder.

[0020] Non-polar solvents that can be used to dissolve non-polar polymers within the scope of the present invention include, but are not limited to, solvents with zero occurring dipole moment, such as hydrocarbons and carbon tetrachloride.

[0021] Polar solvents that can be used to dissolve polar polymers within the scope of the present invention include, but are not limited to, solvents with a non-zero occurring dipole moment, such as dichloromethane, N-methyl-2-pyrrolidone (NMP), and acetone.

[0022] According to a second embodiment of the process according to the invention, the first and second non-polar and polar polymer compositions are free of solvent and can be introduced separately or as a mixture into the extruder for carrying out the mixing step b).

[0023] If the liquid organic electrolyte metal-ion battery component to be prepared is an electrode, the method according to the invention can be used to prepare composite filaments, films, or granules from a thermoplastic polymer blend of at least two immiscible thermoplastic polymers, an electrochemically active material, and a conductive carbon (introduced in mixing step b)). It should be noted that the active material must function within the potential window of the two thermoplastic polymers. Another alternative would be to introduce these fillers into the non-polar polymer solution (first embodiment of the method according to the invention) or directly into the non-polar polymer during the extrusion process (solvent-free route).

[0024] In the case of the positive electrode, the electrochemically active material may be selected from the following compounds: compounds with an olivine structure such as LiFePO4, lamellar compounds of the LiMO2 or NaMO2 type (M represents a metal element selected from Co, Ni, Mn, and Al, either singly or in combination), oxides, sulfides, NaSICON type structure compounds, and spinel structure compounds of the LiMn2O4 type, which contain metal ions in stoichiometric, superstoichiometric, or substoichiometric amounts.

[0025] For the negative electrode, the following compounds are used alone or in mixture: carbon, Li4Ti5O 12 Compounds selected from the group consisting of metals and intermetallic compounds, alloys, silicon, oxides, and sulfides can be used as electrochemically active materials.

[0026] As conductive carbon, carbon nanofibers (commonly abbreviated as CNF) and / or carbon nanotubes (commonly abbreviated as CNT) and / or carbon black may be advantageously used within the scope of the present invention.

[0027] When the liquid organic electrolyte metal-ion battery component to be fabricated is a separator, the method according to the present invention can be used to fabricate composite filaments, films, or granules from a thermoplastic polymer blend comprising at least two immiscible thermoplastic polymers, and free of electrochemically active material and conductive carbon. Advantageously, such a blend of at least two immiscible thermoplastic polymers can further comprise an electrochemically inert insulating material, such as silica, to improve the mechanical strength and / or wettability of the separator by the electrolyte.

[0028] The method according to the invention can produce composite films or filaments and composite granules up to step c). In order to produce organic electrolyte metal-ion battery components from the composite films, filaments or granules obtained in step c), a preferred variant of the method according to the invention can further comprise an additional step d).

[0029] If the product obtained at the end of step c) is in the form of composite filaments or composite granules, an additional step d) will be a 3D printing step for producing cathodes or anodes of liquid organic electrolyte metal ion batteries or separator type parts by FFF or FGF.

[0030] If the product obtained at the end of step c) is in the form of a composite film, an additional step d) is an assembly step for producing metal-ion batteries with liquid organic electrolyte from these composite films, for example in the following configurations: button cells, flexible envelope cells (so-called "pouch cells"), prismatic, cylindrical cells.

[0031] The invention also relates to liquid organic electrolyte metal-ion battery components which may be obtained by a preferred variant of the method according to the invention.

[0032] Preferably, the proportion of electrochemically active material in a battery component according to the invention may be at least 50% by weight relative to the weight of said component, and may range up to 65% by weight in the case of components in the form of filaments and up to 75% by weight in the case of components in the form of granules.

[0033] The method according to the invention therefore makes it possible to produce custom-made batteries that can be adapted to the shape of the object to be supplied with energy as required.

[0034] Depending on the intended application, they can be integrated into objects to save space, maximize storage capacity, or provide better aesthetics than conventional batteries.

[0035] The present invention also relates to an electrochemical cell comprising at least one battery component according to the invention.

[0036] Other advantages and features of the invention will be seen from the following description, given by way of non-limiting example and with reference to the accompanying drawings and examples.

[0037] The following examples illustrate the invention in relation to the figures described above, but do not limit its scope. [Brief explanation of the drawings]

[0038] [Figure 1]1A-1D show schematic diagrams of the different steps of a solvent-based method for conditioning a lithium-ion battery cathode filament according to a first embodiment of the method according to the invention. [Figure 2] 2A to 2D show schematic diagrams of different steps of the dry manufacturing method for lithium-ion battery cathode filaments according to a second embodiment of the method according to the invention (solvent-free route, first variant). [Figure 3] 2A to 2D show schematic diagrams of different steps of the dry manufacturing method for lithium-ion battery cathode filaments according to a second embodiment of the method according to the invention (solvent-free route, second variant). [Figure 4] 1A-1D show schematic diagrams of different steps of the dry manufacturing method for lithium ion battery cathode filaments using a semi-industrial bivis extruder according to a second embodiment of the method according to the invention (solvent-free route, second variant). [Figure 5] 1 shows backscattered electron scanning electron microscope images of the electrode disk surface of Example 1. The image on the left (a) shows the plate surface, and the image on the right (b) shows the nozzle surface. [Figure 6] 1 is a scanning electron microscope image (or SEM image) taken at a cross section of the printed electrode disk of Example 2. [Figure 7] 1 is a scanning electron microscope image (or SEM image) taken at a cross section of the printed electrode disk of Example 3. [Figure 8] 1 is a scanning electron microscope (SEM) image taken at a cross section of a printed electrode disk of Example 4. The center of the electrode disk shows PCL / LTO (white particles) / CNF (long tubes) / PBE and PP (dark background). [Figure 9] FIG. 1 shows the specific capacity as a function of cycle number when cells containing the printed disc obtained in Example 1 (as working electrode), lithium metal (as counter electrode), and glass fiber separator impregnated with LiPF (1 M) electrolyte in EC (ethylene carbonate):DEC (diethyl carbonate) (1:1 by mass) were cycled at ambient temperature. [Figure 10]FIG. 1 shows the specific capacity as a function of cycle number for a cell containing a printed disc obtained in Example 2 (as working electrode), lithium metal (as counter electrode), and a glass fiber separator impregnated with LiPF (1 M) electrolyte in EC:DMC (dimethyl carbonate) (3:7 by mass) cycled at 25° C. [Figure 11] FIG. 1 shows the specific capacity as a function of cycle number for a cell containing a printed disc obtained in Example 3 (as working electrode), lithium metal (as counter electrode), and a glass fiber separator impregnated with LiPF6 electrolyte (1 M) in EC:DMC (3:7 by mass) cycled at 25° C. [Figure 12] FIG. 1 shows the specific capacity as a function of cycle number for cells containing the printed disc obtained in Example 4 (as working electrode), lithium metal (as counter electrode), and glass fiber separator impregnated with LiPF (1 M) electrolyte in EC:MEC (methyl ethyl carbonate) (3:7 by mass) cycled at 25° C. [Figure 13] FIG. 1 shows the specific capacity as a function of cycle number for cells containing the printed disc obtained in Example 5 (as working electrode), lithium metal (as counter electrode), and glass fiber separator impregnated with LiPF (1 M) electrolyte in EC:MEC (methyl ethyl carbonate) (3:7 by mass) cycled at 25° C. [Figure 14] Conductivity values ​​of a printed separator made of a PP / PCL polymer blend (50 / 50 by mass) impregnated with LiPF6 electrolyte (1 M) in EC / MEC (3 / 7 by mass) are compared with those obtained for a glass fiber separator and a commercial PP separator. [Figure 15] Schematic representation of the main preparation steps for the production of a composite disc from solvent-processed filaments, the disc containing only a single thermoplastic polar polymer of the PLA type. [Figure 16]Figure 1 shows the evolution of specific capacity as a function of cycle number when cells containing printed discs based on the positive electrode active materials graphite (+PLA, PEGDME500, graphite, C45) (as working electrode), lithium metal (as counter electrode), and glass fiber separator impregnated with LiPF6 (1 M) electrolyte in EC:DEC (1:1 mass ratio) are cycled at room temperature. [Figure 17] Transmission electron microscope images of cross sections made with the negative electrode filament, including small CSP carbon black particles dispersed in PLA (gray background) in part (a) and a higher magnification image of the area close to the graphite particles (area circled in red) in part (b). [Figure 18] 1 is a scanning electron microscope image of cracks observed in the negative electrode of Example 4 after cycling. DETAILED DESCRIPTION OF THE INVENTION

[0039] (Example) The raw materials of the polymer composition (polar polymer, non-polar polymer, polar and non-polar solvents), electrochemically active material, and conductive carbon, as well as the tools used (extruder and 3D printer) are described in detail below.

[0040] raw material First Polymer Composition - First non-polar polymer: Polypropylene (PP) - Second non-polar polymer: polyolefin elastomer (PBE) - Non-polar solvents: cyclohexane; Second Polymer Composition - Polar polymers: polyethylene oxide (PEO), polycaprolactone (PCL) - Polar solvent: dichloromethane Electrochemically active materials (or active materials): - LiFePO4 (commonly called LFP, particle size D50: 2-6μm) - Li4Ti5O 12 (usually referred to by the abbreviation LTO). Conductive carbon: - a mixture of carbon nanofibers (usually abbreviated as CNF: width 100 nm x length 20-200 μm) and carbon nanotubes (usually abbreviated as CNT: width 9.5 nm x length 1.5 μm); - Carbon nanofiber (CNF: width 100nm x length 20~200μm) - Carbon black (C45)

[0041] tools - a laboratory extruder sold by Thermo Fisher Scientific under the trade name HAAKE MiniLab III, - a bivis semi-industrial extruder sold by Thermo Fisher Scientific under the trade name Process 11; - 3D printers sold by Prusa under the trade name Original Prusa i3 MK3 3D; - Single-screw extruder sold under the trade name Filabot Original by Filabot Triex LLC, USA.

[0042] Example 1 Solvent-based preparation of lithium-ion battery cathode disks according to a first embodiment of the method according to the invention In this example, a lithium-ion battery cathode disk is produced by 3D printing according to a first embodiment of the method according to the invention.

[0043] A composite film fragment prepared in a solvent was fed into an extruder capable of filament production. This film consisted of two thermoplastic polymers: polypropylene (PP), which is inert to the electrolyte, and poly(ethylene oxide) (PEO), which serves to transport the electrolyte within the electrode by impregnation. The active material was LiFePO4 (particle size D50: 2-6 μm), and two types of conductive carbon: nanofibers (CNF: 100 nm wide x 20-200 μm long) and nanotubes (CNT: 9.5 nm wide x 1.5 μm long). The mass percentages were as follows: PP: 33%, PEO: 13%, LiFePO4: 49%, CNF: 2.5%, CNT: 2.5%.

[0044] The preparation of the composite film (as shown in Figure 1) involves the following steps: PP and PEO polymers are separately pre-dissolved in cyclohexane at 110 °C and dichloromethane at room temperature, respectively. The two solutions are mixed, and then the fillers (carbon, then LiFePO4) are added. The mixture is spread on a glass plate. After drying, the thin film is cut into pieces and fed into an extruder.

[0045] Filaments with a diameter of 2 mm were obtained at a temperature of 190 °C using a laboratory extruder equipped with two coaxial shafts. 3 The residence time of the material in the screw was about 15 minutes, and the screw rotation speed was 50 rpm. The electrical conductivity of the filament thus obtained was about 9 × 10 -2 S / cm.

[0046] This filament is fed into a printer (Original Prusa i3 MK3 3D) with a nozzle temperature of 260°C and a plate temperature of 100°C to print a disk with a diameter of 12.7 cm and a thickness of 170 μm.

[0047] Analysis of the image of the printed disc surface, taken with a scanning electron microscope in backscattered electron mode (see Figure 5), clearly shows the immiscibility of the polymers: the active material LiFePO4 (LFP) and the conductive carbon particles are present only within the PP polymer.

[0048] The printed disks were cycled in an electrochemical cell containing this working electrode against a lithium metal-based counter electrode and a glass fiber separator impregnated with a liquid electrolyte consisting of LiPF6 (1M) lithium salt solubilized in a 1:1 mixture of EC (ethylene carbonate) and DEC (diethyl carbonate) by mass.

[0049] The cell is 2.6~4V vs Li at room temperature. + The calculated capacity per gram of active material LFP (obtained at rates C / 40 (150 mAh / g) and C / 20 (130 mAh / g)) is close to the theoretical capacity of LFP, 170 mAh / g, as shown in Figure 9.

[0050] Example 2 Dry preparation of lithium-ion battery cathode disks according to a second embodiment of the method according to the invention (solvent-free route, first variant) This example describes the steps of the dry preparation of a lithium-ion battery cathode disk according to a second embodiment of the method according to the invention (as shown in FIG. 2).

[0051] Filaments (2 mm diameter) were produced using a laboratory extruder equipped with two co-axial shafts. The extrusion temperature was set at 200°C and the extruder (7 cm 3 The residence time of the material in the mixer is about 15 minutes, and the screw rotation speed is 50 rpm.

[0052] The extruder was fed with the following components: two thermoplastic polymers in the form of granules: polypropylene (PP) polymer, which is inert to the electrolyte, and polycaprolactone (PCL), which serves to transport the electrolyte within the electrode by impregnation; the active material LiFePO4 (particle size D50: 2-6 μm); and nanofiber-type (CNF: 100 nm wide x 20-200 μm long) conductive carbon, in the following mass percentages: PP: 23.7%, PCL: 15.8%, LiFePO4: 55%, CNF: 5.5%. These components were introduced into the extruder at 215 °C in two stages. First, the PP and PCL granules were introduced to ensure uniformity of the molten polymer mixture, followed by the addition of a homogeneous mixture of fillers (LiFePO4 and carbon). These two powders were premixed for 10 hours in a vessel containing zirconium beads undergoing three-dimensional motion.

[0053] The electrical conductivity of the resulting filament is about 8.3 S / m.

[0054] This filament is fed into a printer (Original Prusa i3 MK3 3D) with a nozzle temperature of 220°C and a plate temperature of 100°C to print a disk with a diameter of 12.5 cm and a thickness of 200 μm.

[0055] Analysis of the image taken at the center of the electrode using a scanning electron microscope (see Figure 6) confirmed the vein-like morphology of the PCL, specifically showing that PCL veins (red area on the left) are present in the LFP (white particles) / CNF (green area on the left) / PP (dark background) matrix.

[0056] The printed disks were cycled in an electrochemical cell containing this working electrode against a lithium metal-based counter electrode and a glass fiber separator impregnated with a liquid electrolyte consisting of LiPF6 (1 M) lithium salt solubilized in a 3:7 mixture of EC (ethylene carbonate) and DMC (dimethyl carbonate) by mass.

[0057] The assembled cell is then stored at 47°C for 24 hours to allow the electrolyte to penetrate into the electrodes. The cell is then charged to 2.6-4 V vs. Li at 25°C. + The cells were cycled at a constant current of 1000 mAh / Li. As shown in Figure 10, the calculated capacities per gram of active material LFP were obtained at rates of C / 40 (156 mAh / g), C / 20 (146 mAh / g), and C / 10 (138 mAh / g), which are close to the theoretical capacity of LFP, 170 mAh / g.

[0058] Example 3 Dry preparation of lithium-ion battery cathode disks according to a second embodiment of the method according to the invention (solvent-free route, second variant) This example describes the steps of the dry preparation of a lithium-ion battery cathode disk according to a second embodiment of the method according to the invention (as shown in FIG. 3).

[0059] To produce filaments that can be wound under industrial conditions, the polymer inert to the electrolyte (polypropylene) is partially replaced by an elastomer (second variant of the second embodiment of the method according to the invention).

[0060] Filaments (2 mm diameter) were produced using a laboratory extruder equipped with two co-axial shafts. The extrusion temperature was set at 215°C and the extruder (7 cm 3 The residence time of the material in the mixer is about 15 minutes, and the screw rotation speed is 50 rpm.

[0061] The extruder is fed with three thermoplastic polymers in the form of granules: a polypropylene (PP) polymer, which is inert to the electrolyte; a polyolefin elastomer (PBE), which gives the final filament high flexibility and is also inert to the electrolyte; and polycaprolactone (PCL), which complements this mixture and serves to transport the electrolyte within the electrode by impregnation. The active materials, LFP and nanofiber-type carbon (CNF: width 100 nm x length 20-200 μm), are introduced according to the following mass percentages: PP: 17.775%, PBE: 5.925%, PCL: 15.8%, LFP: 55%, CNF: 5.5%.

[0062] These ingredients were introduced into the extruder in two stages: first, PP and PCL granules were introduced to ensure the homogeneity of the molten polymer mixture, followed by the addition of a homogeneous mixture of fillers (LiFePO4 and carbon). These two powders were premixed for 10 hours in a vessel containing zirconium beads undergoing three-dimensional motion.

[0063] The electrical conductivity of the filament thus obtained is about 4.84 S / m.

[0064] This filament is fed into a 3D printer with a nozzle temperature of 220°C and a plate temperature of 50°C to print a disk with a diameter of 12.5 cm and a thickness of 200 μm.

[0065] Analysis of the image taken at the center of the electrode using a scanning electron microscope (see Figure 7) confirms the growth of PCL in the LFP / CNF / PP and PBE matrix.

[0066] The printed disks were cycled in an electrochemical cell containing this working electrode and a glass fiber separator against a lithium metal-based counter electrode impregnated with a liquid electrolyte: a mixture of EC (ethylene carbonate), DMC (dimethyl carbonate), and LiPF6 (1 mol / L) in a mass ratio of 3:7.

[0067] The assembled cell is then stored at room temperature for 24 hours to allow the electrolyte to penetrate into the electrodes. The cell is then charged to 2.8-4 V vs. Li at 25°C. + The capacity per gram of LiFePO4 active material was calculated and obtained at rates of C / 40 (165 mAh / g), C / 20 (149 mAh / g), C / 10 (143 mAh / g), C / 5 (131.5 mAh / g), C / 2 (102 mAh / g), and C / 10 (143 mAh / g), as shown in Figure 11.

[0068] Example 4 Dry preparation of a lithium-ion battery negative electrode disk according to a second embodiment of the method according to the invention This example describes the steps of the dry preparation of a lithium-ion battery negative electrode disk according to a second embodiment of the method according to the invention (as shown in FIG. 3).

[0069] To produce a spoolable filament, the polymer inert to the electrolyte (polypropylene) is partially replaced by an elastomer (second variant of the second embodiment of the method according to the invention).

[0070] Filaments (2 mm diameter) were produced using a laboratory extruder equipped with two co-axial shafts. The extrusion temperature was set at 215°C and the extruder (7 cm 3 The residence time of the material in the mixer is about 15 minutes, and the screw rotation speed is 50 rpm.

[0071] The extruder is fed with three thermoplastic polymers in the form of granules: polypropylene (PP) polymer, which is inert to the electrolyte; polyolefin elastomer (PBE), which gives the final filament high flexibility and is also inert to the electrolyte; and polycaprolactone (PCL), which complements this mixture and transports the electrolyte within the electrode by impregnation. The LTO active material and carbon nanofibers (CNF, 100 nm wide x 20-200 μm long) are introduced according to the following mass percentages: PP: 15.642%, PBE: 7.821%, PCL: 15.8%, LTO: 55%, CNF: 5.5%.

[0072] These ingredients were introduced into the extruder in two stages: first, PP, PBE, and PCL granules were introduced to ensure the homogeneity of the molten polymer mixture, and then a homogeneous mixture of fillers (LTO and carbon) was added. These two powders were premixed for 10 hours in a vessel containing zirconium beads undergoing three-dimensional motion.

[0073] The electrical conductivity of the filament thus obtained is about 3.91 S / m.

[0074] This filament is fed into a printer (Original Prusa i3 MK3 3D) with a nozzle temperature of 220°C and a plate temperature of 50°C to print a disk with a diameter of 12.5 cm and a thickness of 200 μm.

[0075] Analysis of images taken at the center of the electrode using a scanning electron microscope (see Figure 8) confirms the vein-like morphology of the PCL.

[0076] The printed disks were cycled in an electrochemical cell containing this working electrode and a glass fiber separator against a lithium metal-based counter electrode impregnated with a liquid electrolyte consisting of LiPF6 (1 M) lithium salt solubilized in a 3:7 mixture of EC (ethylene carbonate) and MEC (methyl ethyl carbonate) by mass.

[0077] The assembled cell is then stored at room temperature for 24 hours to allow the electrolyte to penetrate the electrodes. The cell is then charged at 25°C with 1-2 V vs. Li. + The LTO active material was cycled at a constant current of 0.1 V / Li. As shown in Figure 12, the calculated capacities per gram of LTO active material were obtained at rates of C / 40 (136 mAh / g), C / 20 (129 mAh / g), C / 10 (110 mAh / g), C / 5 (70 mAh / g), C / 2 (20 mAh / g), and C / 10 (110 mAh / g).

[0078] Example 5 Dry preparation of a lithium-ion battery negative electrode disk according to a second embodiment of the method according to the invention This example describes the steps of the dry preparation of a lithium-ion battery negative electrode disk according to a second embodiment of the method according to the invention (as shown in FIG. 4).

[0079] To produce filaments that can be wound under industrial conditions, the polymer inert to the electrolyte (polypropylene) is partially replaced by an elastomer in a larger amount than in Example 4 (second variant of the second embodiment of the method according to the invention).

[0080] Filaments (2 mm diameter) of the final composition PP / PBE / PCL / LTO / CNF / CNT (mass percentages 11.85 / 11.85 / 15.8 / 55 / 2.75 / 2.75) are produced using a semi-industrial extruder equipped with two coaxial shafts. The extrusion temperature is set to 215 °C. The screw torque is set to 6 Nm.

[0081] The extruder is first fed with three thermoplastic polymers in the form of granules: a polypropylene (PP) polymer, which is inert to the electrolyte; a polyolefin elastomer (PBE), which gives the final filament high flexibility and is also inert to the electrolyte; and polycaprolactone (PCL), which complements this blend to transport the electrolyte within the electrode by impregnation. The resulting polymer filaments are then chopped into granules.

[0082] These granules are mixed with the active material LTO and two types of carbon: one nanofiber type (CNF: 100 nm wide x 20-200 μm long) and the other nanotube type (CNT: 9.5 nm wide x 1.5 μm long). 50 g of the material is mixed for 10 hours in a vessel containing zirconium beads undergoing three-dimensional motion.

[0083] The mixture is returned to the extruder. The filament thus obtained is fed into a printer (Original Prusa i3 MK3 3D) with a nozzle temperature of 220°C and a plate temperature of 50°C to print a disk with a diameter of 12.5 cm and a thickness of 200 μm.

[0084] The printed disks were cycled in an electrochemical cell containing this working electrode and a glass fiber separator against a lithium metal-based counter electrode impregnated with a liquid electrolyte consisting of LiPF6 (1 M) lithium salt solubilized in a 3:7 mixture of EC (ethylene carbonate) and MEC (methyl ethyl carbonate) by mass.

[0085] The assembled cell is then stored at room temperature for 24 hours to allow the electrolyte to penetrate the electrodes. The cell is then charged at 25°C with 1-2 V vs. Li. + The electrodes were cycled at a constant current of 0.1 mA / Li. As shown in Figure 13, the calculated capacities per gram of LTO active material were obtained at rates of C / 40 (140.3 mAh / g), C / 20 (138 mAh / g), C / 10 (134.3 mAh / g), C / 5 (129.2 mAh / g), C / 2 (110.1 mAh / g), and C / 10 (135.2 mAh / g). Note that the industrial method results in a significant improvement in the performance of printed electrodes at high cycling rates (compare C / 5 and C / 2 in Figures 12 and 13).

[0086] Example 6 Dry preparation of lithium-ion battery separators according to the first and second embodiments of the method according to the invention In this example, lithium ion battery separator disks are manufactured by FFF (3D printing).

[0087] Filaments (2 mm diameter) were produced using a laboratory extruder (HAAKE MiniLab III, Thermo Scientific) equipped with two co-axial shafts. The extrusion temperature was set at 215°C, and the extruder (7 cm 3 The residence time of the material in the mixer is about 15 minutes, and the screw rotation speed is 50 rpm.

[0088] The extruder is fed with two thermoplastic polymers in the form of granules of the non-polar polymer PP (polypropylene) and the polar polymer PCL (polycaprolactone) according to the following mass percentages: PP: 60%, PCL: 40%.

[0089] The obtained filament is fed into a 3D printer (Original Prusa i3 MK3 3D) with a nozzle temperature of 220°C and a plate temperature of 50°C to print a disk with a diameter of 12.5 cm and a thickness of 200 μm.

[0090] The printed separator was impregnated with a liquid electrolyte consisting of LiPF6 (1 M) lithium salt dissolved in a mixture of EC and MEC in a mass ratio of 3:7, and then introduced into an electrochemical cell to measure the ionic conductivity at 25 °C.

[0091] The obtained ionic conductivity was 1.87 × 10 -4 S / cm, respectively 1.2 × 10 -3 and 3.1 × 10 -3 This is close to the conductivity of a commercial polypropylene separator (25 μm thick, 50% porosity) and a glass fiber separator, both of which have a conductivity of 100 μm / cm.

[0092] Comparative Example CE1: Single Polymer (PLA) In this example, a lithium-ion battery anode disk was fabricated by 3D printing using the Fused Filament Fabrication (FFF) method. Pieces of a solvent-prepared composite film were fed into an extruder used to produce the filament. This example highlights the challenges encountered when incorporating a single polar thermoplastic polymer into a part.

[0093] The film is made of thermoplastic polymer PLA (polylactic acid) and active material graphite (TIMREX SLS graphite: 1.5 mm). 2 g -1 , d 50 = 14 μm, d 90 = 26 μm, supplied by Timcal) and a conductor of carbon super P type (62 μm 2 / g) and plasticizer PEGDME500 (poly(ethylene glycol) dimethyl ether, molar mass approximately 500) in the following weight percentages: PLA: 33%, PEGDME500: 13%, graphite: 49%, C45: 5%. The plasticizer is added to impart a minimum degree of flexibility to make the filament printable. Without the addition of a plasticizer, the film would be very brittle.

[0094] The preparation of the composite film involves the following steps: PLA polymer is dissolved in dichloromethane at room temperature for 2 hours, then plasticizer and fillers (C45 carbon and graphite) are added. These two powders, C45 and graphite, are premixed for 10 hours in a vessel containing zirconium beads undergoing three-dimensional motion.

[0095] The mixture is spread onto a glass plate. After drying (as shown in Figure 15), the thin film is cut into small pieces and fed into an extruder.

[0096] Filaments with a diameter of 2 mm are produced using a single screw extruder (Filabot Original) at a temperature of 190°C.

[0097] The printed disks were cycled in an electrochemical cell containing this working electrode against a lithium metal-based counter electrode and a glass fiber separator impregnated with a liquid electrolyte consisting of LiPF6 (1M) lithium salt solubilized in a 1:1 mixture of EC (ethylene carbonate) and DEC (diethyl carbonate) by mass.

[0098] The assembled cell is then stored at room temperature for 24 hours to allow the electrolyte to soak into the electrodes. At room temperature, the cell exhibits a voltage of 2.6-4 V vs. Li + The electrode is cycled at a constant current of 0.1 V / Li.

[0099] On the other hand, a regular increase in capacity was observed during the first six cycles (Figure 16), reflecting the difficult and gradual impregnation of the electrode disks. On the other hand, the calculated capacities per gram of active material (graphite) obtained at different rates are significantly lower than the theoretical capacity of graphite, 372 mAh / g. This is explained by a discontinuous electrical percolation pathway associated with the low carbon / polymer volume ratio (Figure 17).

[0100] After cycling, the electrode discs tend to fracture due to gelation of the PLA polymer and electrolyte (Figure 18). These discs have two major drawbacks: slow electrolyte impregnation, resulting in loss of mechanical integrity during cycling, and poor electrochemical performance due to low electrical percolation.

Claims

1. 1. A method for producing composite filaments, films, or granules for liquid organic electrolyte metal-ion battery components, comprising: a. providing or preparing at least two thermoplastic polymer compositions; a first non-polar polymer composition comprising a first non-polar thermoplastic polymer, the first non-polar thermoplastic polymer having a melting temperature Tf1 and having no compatibility with a liquid organic electrolyte intended to be incorporated into the metal-ion battery; and a second polar polymer composition comprising a polar thermoplastic polymer, the polar polymer having a melting temperature Tf2 and having an affinity with the liquid organic electrolyte, the non-polar thermoplastic polymer and the first polar thermoplastic polymer being immiscible; b. mixing said at least first and second non-polar and polar polymer compositions to form a thermoplastic polymer mixture; c) introducing the composite composition into an extruder and then extruding to form composite granules, composite filaments, or a film; the extrusion step is carried out at a temperature Te that is equal to or greater than the temperature of the thermoplastic polymer mixture; Thus, the composite granules, composite film, or composite filaments obtained at the end of the extrusion molding process consist of a polymer matrix having a bicontinuous morphology of the polar thermoplastic polymer and the first non-polar thermoplastic polymer.

2. 2. The method according to claim 1, wherein the non-polar polymer is selected from olefins and mixtures thereof, preferably polypropylene (PP) or polyethylene (PE).

3. 2. The method of claim 1, wherein the first polymer composition comprises at least one second non-polar thermoplastic polymer selected from saturated or unsaturated elastomeric non-polar polymers and / or mixtures thereof, preferably a polyolefin-based elastomer (PBE).

4. The method of claim 1 , wherein the polar thermoplastic polymer is selected from esters, ethers, carbonates, polyamides, and PVDF.

5. the first non-polar polymer composition further comprises a non-polar solvent, and the second polar polymer composition further comprises a polar solvent; said step b) of mixing said first and second non-polar and polar polymer compositions is carried out for a duration comprised between 1 minute and 30 minutes at the highest temperature of the two solutions after the non-polar and polar polymers are completely dissolved in their respective solvents; 10. The method of claim 1, further comprising, between the mixing step b) and the extruding step c), a step b') of spreading the composite composition on a flat surface to form a composite film, followed by a drying step b''), wherein the composite film is then cut into pieces in a cutting step b''') for insertion into the extruder.

6. 6. The method according to claim 5, wherein the non-polar solvent is a solvent having a zero occurring dipole moment, preferably selected from hydrocarbons and carbon tetrachloride.

7. 6. The method according to claim 5, wherein the polar solvent is a solvent having a non-zero occurring dipole moment, preferably selected from dichloromethane, N-methyl-2-pyrrolidone (NMP) and acetone.

8. 10. The method of claim 1, wherein the first non-polar polymer composition and the second polar polymer composition are solvent-free and are introduced into the extruder separately or as a mixture to carry out the mixing step b).

9. 2. The method of claim 1, wherein in the mixing step b) of mixing the thermoplastic polymer mixture, an electrochemically active material and a conductive carbon are introduced.

10. The liquid organic electrolyte metal-ion battery component is a positive electrode, and the electrochemically active material is LiFePO ４ Olivine structure compounds such as LiMO ２ or NaMO ２ Lamellar compounds of the type (wherein M represents a metal element selected from Co, Ni, Mn, and Al, either singly or in combination), oxides, sulfides, NaSICON-type structure compounds, and LiMn ２ O ４ 10. The method of claim 9, wherein the metal ion is selected from spinel structure compounds of the type having a stoichiometric, superstoichiometric or substoichiometric amount.

11. The liquid organic electrolyte metal ion battery component is a negative electrode, and the electrochemically active material is one of the following compounds used alone or in mixture: carbon, Li ４ Ti ５ O １２ 10. The method of claim 9, wherein the metal is selected from metals and intermetallic compounds, alloys, silicon, oxides and sulfides.

12. The method of claim 9, wherein the conductive carbon comprises carbon nanofibers (CNF) and / or carbon nanotubes (CNT) and / or carbon black.

13. 10. The method of claim 1, wherein the liquid organic electrolyte metal-ion battery component is a separator and the thermoplastic polymer mixture is free of electrochemically active materials and conductive carbon, and optionally contains a charge.

14. 14. The method according to claim 13, wherein in the mixing step b) an electrochemically inert insulating material, preferably silica, is introduced.

15. 10. The method of claim 1, further comprising a 3D printing step to fabricate a liquid organic electrolyte metal ion battery component from the composite filaments or composite granules.

16. 10. The method of claim 1 further comprising assembling the composite film to produce a liquid organic electrolyte metal-ion battery component.

17. 17. A liquid organic electrolyte metal ion battery component, the component possibly being obtainable by the method of claim 15 or 16.

18. 18. The component of claim 17, wherein the proportion of electrochemically active material is at least 40% by weight relative to the weight of the component.

19. Electrochemical cell comprising at least one component as defined in claim 17.

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