3D printing filament for a lithium-ion battery

Abstract

A 3D printing filament (1) comprising (i) a lithium-ion battery (9) with a coaxial structure, (ii) a thermally insulating layer (7) made of a material having a thermal conductivity <1 W / mK and arranged coaxial to coat, and in contact with, an outer layer (6) of said lithium-ion battery (9), and (iii) an outer coating layer (8) arranged coaxial to coat and in contact with said thermally insulating layer (7). The outer coating layer (8) is made of a material suitable for use in 3D printing. The lithium-ion battery (9) with a coaxial structure comprises multiple coaxial layers identifying, from the inside outside : an inner current collector (2), a first electrode layer (3) arranged to coat said first current collector (2), a solid or semi-solid electrolyte layer (4) arranged to coat said first electrode layer (3), a second electrode layer (5) arranged to coat said electrolyte layer (4) and an outer current collector layer (6) arranged to coat said second electrode layer (5).

Description

[0001] 3D PRINTING FILAMENT FOR A LITHIUM-ION BATTERY

[0002] Cross-Reference to Related Applications

[0003] This Patent Appl ication claims priority from European Patent Application no . 24210238 . 2 filed on October 31 , 2024 and from Italian Patent Application no . 102025000000564 filed on January 15 , 2025 , the entire disclosure of which is incorporated herein by reference .

[0004] Technical Field

[0005] This invention relates to a lithium-ion battery- operated 3D printing filament , the characteristics of which are such that a functional element with energy storage capacity, called a structural battery, can be produced .

[0006] The possibility of producing a structural battery by means of 3D printing makes it possible to meet the various structural and functional requirements of the batteries and, therefore , to signi ficantly expand its application possibilities .

[0007] State of the Art

[0008] One of the challenges that the aerospace industry will have to face in the near future will certainly concern the protection of the environment , especially considering the continuous increase in air traf fic . For some time , the strategy has been to limit in- flight emissions of greenhouse gases and pollutants by using electricity for both propulsive and non-propulsive purposes ( for example , secondary systems ) .

[0009] The use of electricity involves the presence of battery packs on vehicles , which pose a number of issues due to their weight and volume .

[0010] In order to overcome the above-mentioned issues , research has focused on the production of multi functional structures that not only provided their own speci fic function but also acted as structural elements and provided energy storage . The multi functional structure would, therefore , fully integrate the energy storage system by acting as an accumulator .

[0011] These structures are commonly referred to as structural batteries .

[0012] Generally, structural batteries have been made by incorporating a battery within an existing functional structure . In other words , battery housing seats were built into the existing functional structures . This signi ficantly reduces the space required for simply housing batteries . However, this solution suf fers from the limitation that the battery housings are constrained by the shape of the existing functional structure .

[0013] There was , therefore , a need for structural batteries that had greater versatility and functionality than the prior art . The inventors of this invention have developed a class of filaments for 3D printing, the technical characteristics of which are such that they meet the above requirement .

[0014] Description of the Invention

[0015] The subj ect of this invention is a 3D printing filament comprising ( i ) a lithium-ion battery with a coaxial structure , ( ii ) a thermally insulating layer made of a material having a thermal conductivity <1 W / mK and arranged coaxial to , and in contact with, an outer layer of said lithium-ion battery, and ( iii ) an outer coating layer arranged coaxial to , and in contact with, said thermally insulating layer ; said outer coating layer being made of a material suitable for use in 3D printing; said lithium-ion battery with a coaxial structure comprising multiple coaxial layers identi fying, from the inside outside : an inner current collector, a first electrode layer arranged to coat said first current collector, a solid or semi-solid electrolyte layer arranged to coat said first electrode layer, a second electrode layer arranged to coat said electrolyte layer and an outer current collector layer arranged to coat said second electrode layer .

[0016] Said outer coating layer is preferably made of thermoplastic material .

[0017] The thermoplastic material is preferably from the group consisting of : PEEK, PEI , PET , PC, ABS , PA, PLA, TPU and their blends .

[0018] The thermally insulating layer i s preferably composed of a silicon-based material or a material from the ceramic family, preferably YSZ or the resin family, preferably polyester or epoxy-based .

[0019] Said first electrode or said second electrode preferably constitutes the cathode of the lithium-ion battery made of a material from the group consisting of : lithium-iron-phosphate ( LiFePO4 ) , lithium-titanate ( LTO) , lithium-cobalt-oxide ( LiCo204 ) , lithium-manganese-oxide ( LiMn2O4 ) , lithium-sulphur ( LiS ) , or nickel-manganese-cobalt (NMC ) .

[0020] Said first electrode or said second electrode preferably constitutes the anode o f the lithium-ion battery made from a carbon-based material , more preferably it is made from graphite or carbon black .

[0021] Said first electrode is preferably the cathode and said second electrode is the anode of the lithium-ion battery .

[0022] Said electrolyte layer is preferably made of ceramic material or is in the form of a gel supported by a polymer matrix .

[0023] Said filament preferably has a diameter of 3 mm or less .

[0024] Another obj ect of this invention is a method for producing a structural battery comprising a lithium-ion battery; this method being characterised in that it comprises a 3D printing step, wherein a filament according to this invention is used .

[0025] Brief Description of the Drawings

[0026] In order to better understand the invention, a nonlimiting embodiment will now be described by way of example with the help of the figures in the accompanying drawings , in which :

[0027] - Figure 1 is a perspective view, with parts removed for clarity, of a 3D printing filament according to this invention; and

[0028] - Figure 2 is a side view of a functional battery made by a 3D printing process in which the filament in Figure 1 is used .

[0029] Preferred Embodiments of the Invention

[0030] In Figure 1 , a 3D printing filament , according to this invention, is denoted as a whole by reference numeral 1 . The filament 1 has a cylindrical shape and consists of multiple coaxial layers .

[0031] The filament 1 comprises , from the inside outside of the cylindrical structure : a first current collector 2 made of copper with a diameter of 0 . 2 mm ( alternatively, other electrically conductive materials , such as aluminium, may be used) ; a 0 . 04 m thick cathode layer 3 made of LiFePCh and placed around, and in contact with, the current collector 2 ; a 0 . 02 mm thick electrolyte layer 4 made of an electrically insulating but ionic conductive material , which may be a semi-liquid or solid material such as LLZO-P (EO) / LiTFS I and placed around, and in contact with, the cathode layer 3 ; a 0 . 04 mm thick anode layer 5 made of graphite ( alternatively, other carbon-based compounds such as carbon black, carbon fibres or graphene-based compounds may be used) and placed around, and in contact with, the electrolyte layer 4 ; a 0 . 1 mm thick second current collector layer 6 made of aluminium ( alternatively, other electrically conductive materials such as copper may be used) and placed around, and in contact with, the anode layer 5 ; a 0 . 2 mm thick thermally insulating layer 7 made of SiC and arranged around, and in contact with, the second current collector layer 6 ; a 1 mm thick outer coating layer 8 made of PLA and arranged around, and in contact with, the thermally insulating layer 7 .

[0032] The layers 2 to 6 collectively define a lithium-ion battery 9 .

[0033] The layers described above were produced by coextrusion or conventional deposition techniques such as dip coating, spin coating, chemical vapour deposition ( CVD) , electro spinning, or spray deposition, depending on the material characteristics .

[0034] Completing the above example , the cathode layer can be made of one of the following materials : lithium-titanate ( LTO) , lithium-cobalt oxide ( LiCo204 ) , lithium-manganese oxide ( LiMn2O4 ) , lithium-sulphur ( LiS ) , or nickel-manganese- cobalt (NMC ) .

[0035] The electrolyte layer must be solid or semi-solid to prevent physical and electrical contact between the electrodes during lithium-ion conduction . The electrolyte layer must also withstand the mechanical stress and bending that would occur during the printing process as wel l as the high temperatures reached during printing .

[0036] From the above , it follows that the electrolyte layer may also be made of ceramic material or is in the form of a gel supported by a polymer matrix .

[0037] The thermally insulating layer is intended to protect the battery materials from the high temperatures reached by the thermoplastic material during 3D printing .

[0038] The material constituting the layer 8 must be suitable for processing by 3D printing and can be made of a thermoplastic material from the group consisting of : PEEK, PEI , PET , ABS , PA, PC, PLA, TPU and their compatible blends or formulations .

[0039] The choice of polymer material is made according to the requirements of the 3D printer used and the structural / thermal / chemical needs of the finished product .

[0040] The filament 1 was used for producing a structural battery by means of 3D printing, whose operating conditions are listed below .

[0041] Figure 2 shows a structural battery 10 made from the filament 1 described above using a 3D printing process . The structural battery 10 comprises a supporting structure 11 consisting of the filament 1 , and within which a lamp holder, not illustrated, is housed, on which a bulb 12 is mounted . The lamp holder is connected with the first 2 and the second 6 filament 1 collector, which forms the supporting structure 11 , to receive the power supply .

[0042] Speci fically, the 3D printing process was conducted using Fused Deposition Modelling ( FDM) technology from a three-dimensional model obtained by Computer-Aided Design ( CAD) . The filament that is the subj ect of this invention was extruded through a heated noz zle and the material was deposited in successive layers according to a predefined path to produce the final shape of the component . Extrusion took place at a constant pressure and flow rate , ensuring uni form deposition of the material , which solidifies rapidly on contact with the construction surface , enabling the gradual production of the manufactured obj ect .

[0043] The parameters used in FDM technology, in which the filament 1 described above was used for producing the structural battery 10 , are listed below :

[0044] - Extrusion Temperature : Te = 215 / 220 ° C

[0045] Print plate temperature : Tb = 50 ° C Nozzle diameter: D = 2 mm.

[0046] - Extrusion Multiplier / Flow Rate: EM = 100% (or 1)

[0047] - Retraction: = OFF

[0048] Fan cooling speed: variable between 30% and 50% (bottom to top layers, continuously)

[0049] - Average print speed: Vav = 60 mm / s

[0050] - Height of the print layer: LH = 1.8 / 2.0 mm

[0051] The design of the structure and the print pattern were such as to ensure continuous extrusion, eliminating non- extrusive print-head movements. In this respect, one possible printing pattern is the Spiralize / Vase mode.

[0052] In contrast to the above, the nozzle diameter can even be greater than 2 mm, depending on the requirements sought for the end product in terms of structural strength and mechanical resistance.

[0053] In addition, printing under over-extrusion conditions, that is with EM > 1, can also be considered, depending on the needs arising from changes in flow conditions during printing .

[0054] As may be immediately apparent to a person skilled in the art, the possibility of producing a structural battery with the 3D printing technique using the filament that is the subject of this invention guarantees high versatility in both functional and aesthetic terms. In this way, the supply of electricity directly from functional elements, the form of which can be determined arbitrarily, can be ensured .

[0055] In other words , it is possible to customise the structural battery, meeting both structural and energy requirements at the same time .

Claims

C L A I M S1. A 3D printing filament (1) comprising (i) a lithium- ion battery (9) with a coaxial structure, (ii) a thermally insulating layer (7) made of a material having a thermal conductivity <1 W / mK and arranged coaxial to, and in contact with, an outer layer (6) of said lithium-ion battery (9) , and (iii) an outer coating layer (8) arranged coaxial to, and in contact with, said thermally insulating layer (7) ; said outer coating layer (8) being made of a material suitable for use in 3D printing; said lithium-ion battery (9) with a coaxial structure comprising multiple coaxial layers identifying, from the inside outside: an inner current collector (2) , a first electrode layer (3) arranged to coat said first current collector (2) , a solid or semi-solid electrolyte layer (4) arranged to coat said first electrode layer (3) , second electrode layer (5) arranged to coat said electrolyte layer (4) and an outer current collector layer (6) arranged to coat said second electrode layer (5) .

2. The 3D printing filament according to claim 1, characterised in that said outer coating layer (8) is made of thermoplastic material.

3. The 3D printing filament according to claim 2, characterised in that the thermoplastic material is from the group consisting of PEEK, PEI, PET, PC, ABS, PA, PLA, TPU and their blends.

4. The 3D printing filament according to any of the previous claims, characterised in that the thermally insulating layer (7) is composed of a silicon-based material or a material from the ceramic family, preferably YSZ or the resin family, preferably polyester or epoxy-based.

5. The 3D printing filament according to one of the previous claims, characterised in that said first electrode or said second electrode constitutes the cathode of the lithium-ion battery made of a material from the group consisting of: lithium-iron-phosphate (LiFePO4) , lithium- titanate (LTO) , lithium-cobalt-oxide (LiCo204) , lithium- manganese-oxide (LiMn2O4) , lithium-sulphur (LiS) , or nickel- manganese-cobalt (NMC) .

6. The 3D printing filament according to claim 5, characterised in that preferably said first electrode or said second electrode constitutes the anode of the lithium- ion battery made of a carbon-based material, more preferably it is made of graphite or carbon black.

7. The 3D printing filament according to claim 6, characterised in that said first electrode is the cathode and said second electrode is the anode of the lithium-ion battery .

8. The 3D printing filament according to one of the previous claims, characterised in that said electrolyte layer (4) is made of ceramic material or in the form of agel supported by a polymer matrix .9 . The 3D printing filament according to one of the previous claims , characterised in that it has a diameter of 3 mm or less . 10 . A structural battery ( 10 ) characterised in that it is made by 3D printing using a filament according to one of the previous claims .11 . A method for producing a structural battery comprising a lithium-ion battery; this method being characterised in that it comprises a 3D printing step, wherein a filament according to one of claims 1 - 9 is used .

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