Electrochemical pouch cell for structural battery

Abstract

An electrochemical structural battery pouch cell (1) comprising a core (2) developing along a main plane (1a) and including a plurality of walls (3) developing perpendicularly to the main plane (1a) along respective development trajectories (3a) defined on the main plane (1a) and formed such that the coupling of the walls (3) realizes a structure having a honeycomb cross-section on the main plane (1a), each of the walls (3) defining a profile (4), on a section plane (1b) perpendicular to the main plane (1a) and the development trajectories (3a), including at least a first layer (40) made of aluminum or its alloy, a second layer (41) made of aluminum or its alloy, a first separation layer (42) arranged between the first and second layers (40, 41) and including insulating material, and welding means (43) arranged at opposite ends, relative to the main plane (1a), of the first and second layers (40, 41) so as to close the first separation layer (42) between layers (40, 41) and welding means (43); in which the first layer (40) is coated with a first electrode (40a) of your choice between an anode and a cathode, and the second layer (41) is coated with a second electrode (41a) of your choice between an anode and a cathode so that the layers (40, 41) each simultaneously realize a collector and a barrier with respect to the environment outside the cell (1).

Description

[0001] DESCRIPTION

[0002] ELECTROCHEMICAL POUCH CELL FOR STRUCTURAL BATTERY

[0003] This invention relates to an electrochemical pouch cell for structural battery of the type specified in the preamble of the first claim.

[0004] Several structural batteries are currently under development. In general, structural batteries include innovative multifunctional composite materials capable of supporting mechanical loads while simultaneously storing electrical energy. Such batteries are significantly smaller in size and weight than conventional batteries of equal energy efficiency. Indeed, structural batteries have many potential applications. Possible fields of use include: the automotive sector, the aerospace sector, the aviation and shipbuilding sectors, the construction sector, the energy sector, in particular the renewable energy sector, and more.

[0005] The adoption of such structural batteries is particularly appropriate for solving space-related issues.

[0006] For example, as is well known, the main problem of electric cars today is their short range. In order to ensure high autonomies, it would be necessary to implement large conventional batteries on board the vehicles. However, the latter have the disadvantage of greatly increasing the weight of the vehicle and thus increasing energy consumption as a result. To overcome this problem, cars having accumulators built into the body have been designed. Some parts of the body are made of composite materials whose purpose is to store energy while providing mechanical strength to the structure. Such an integrated construction concept can be applied in all of the areas mentioned above involving, in addition, significant changes in the shape and / or size of electrical structures and devices.

[0007] In recent years, the most studied approach to making multifunctional composite materials has been to incorporate active materials related to lithium-ion chemistries within composite laminates to create a multifunctional structure. For example, the properties of lithium-ion batteries can thus be combined with the properties of carbon fiber composite materials. In fact, carbon fibers provide structural strength and, in addition, they represent the negative electrode in lithium-ion batteries. These fibers must be placed within a matrix that ensures high mechanical performance. The matrix must also allow for the ion exchange necessary for energy storage between the negative electrode and the positive electrode. Such a matrix is made mainly of polymeric materials because liquid electrolytes are not suitable in these configurations to support mechanical loads.

[0008] An alternative approach is to make structural electrodes, structural separators, and even a structural electrolyte that are themselves capable of forming a battery, such as lithium-ion battery.

[0009] The prior art just described includes some important drawbacks.

[0010] In particular, the solutions studied so far have not produced a satisfactory combination of high energy storage and high structural strength.

[0011] Some technologies have the problem of structural deformation during the charging and discharging process.

[0012] In addition, damage or malfunction could result in the replacement of large structural portions involving high costs.

[0013] In this situation, the technical task underlying this invention is to devise an electrochemical pouch cell for structural battery capable of substantially overcoming at least part of the aforementioned drawbacks.

[0014] In the context of this technical task, it is an important aim of the invention to obtain an electrochemical pouch cell for structural battery that provides high mechanical strength and, at the same time, high energy efficiency.

[0015] In addition, such a structural battery should not be subject to deformation during the charging and discharging processes.

[0016] Another important purpose of the invention is to make an electrochemical pouch structural battery cell that can be cost-effectively repaired in case of malfunction or damage.

[0017] The technical task and the specified aims are achieved by an electrochemical pouch cell for structural battery as claimed in the annexed claim 1 .

[0018] Preferred embodiments are highlighted in the dependent claims.

[0019] The characteristics and benefits of the invention will be clarified in the following detailed description of some preferred embodiments of the invention, with reference to the accompanying drawings, wherein:

[0020] Fig. 1 shows a cross-section view of an electrochemical pouch cell for structural battery according to the invention with a single cell and equipped with an anode and cathode;

[0021] Fig. 2 shows a cross-section view of an electrochemical pouch cell for structural battery according to the invention with a dual cell and equipped with two anodes at the ends and two central cathodes;

[0022] Fig. 3 shows a cross-section view of an electrochemical pouch cell for structural battery according to the invention with a triple cell and equipped with an anode, two cathodes, two anodes and one cathode in this order;

[0023] Fig. 4 shows a cross-section view of an electrochemical pouch cell for structural battery according to the invention wherein first and second layers are in contact with first and second skins, respectively;

[0024] Fig. 5a shows a main plane view of the honeycomb core section of an electrochemical pouch cell for structural battery according to the invention in which the cells are polygonal;

[0025] Fig. 5b shows a main plane view of the honeycomb core section of an electrochemical pouch cell for structural battery according to the invention in which the cells are curved;

[0026] Fig. 5c shows a main plane view of the honeycomb core section of an electrochemical pouch cell for structural battery according to the invention in which the cells are straight;

[0027] Fig. 5d shows a main plane view of the honeycomb core section of an electrochemical pouch cell for structural battery according to the invention in which the cells are mixed; and

[0028] Fig. 6 shows a partial exploded view of an electrochemical pouch cell for structural battery according to the invention in which said interface layer defines a mask.

[0029] In this document, when measurements, values, shapes, and geometric references (such as perpendicularity and parallelism) are associated with words like “approximately” or other similar terms, such as “almost” or “substantially”, they shall be understood as except for errors of measurement or imprecisions due to errors of production and / or manufacturing and, above all, except for a slight departure from the value, measurement, shape, or geometric reference with which it is associated. For example, if associated with a value, such terms preferably indicate a departure of no more than 10% of the value itself.

[0030] Furthermore, when terms such as “first”, “second”, “upper”, “lower”, “main”, and “secondary” are used, they do not necessarily identify an order, relationship priority, or relative position, but they can simply be used to distinguish different components more clearly from one another.

[0031] Unless otherwise specified, as reflected in the following discussions, terms such as "processing”, "computing”, "determination”, "computation”, orthe like are considered to refer to the action and / or processes of a computer or similar electronic computing device that manipulates and / or transforms data represented as physical, such as electronic quantities of records of a computer system and / or memories, in other data similarly represented as physical quantities within computer systems, records, or other information storage, transmission, or display devices.

[0032] Unless otherwise stated, the measurements and data reported in this text shall be considered as performed in International Standard Atmosphere ICAO (ISO 2533:1975).

[0033] With reference to the figures, the electrochemical pouch cell for structural battery according to the invention is globally indicated with the number 1.

[0034] The electrochemical structural battery pouch cell 1 comprises at least a core 2.

[0035] Core 2 is the middle portion of the cell, within which the electrodes are normally distributed.

[0036] Core 2, therefore, is developed along a main plane 1a. Main plane 1a is a virtual plane. Core 2 then forms a kind of plate structure developing along the main plane 1 a and defining its own thickness. For example, core 2 can define a minimum thickness, transverse to main plane 1 a, of 5 mm.

[0037] Thus, core 2 includes a plurality of walls 3.

[0038] Walls 3 run perpendicular to the main plane 1a. Therefore, walls 3 are the elements that determine the thickness of core 2.

[0039] In addition, for example, walls 3 may be 30 pm to 500 pm thick.

[0040] Walls 3 are also developed along respective development trajectories 3a. Development trajectories 3a are defined on the main plane 1a. In addition, the development trajectories 3a are formed in such a way that the coupling of the walls 3 realizes a structure having a honeycomb section on the main plane 1 a.

[0041] Thus, walls 3 can develop on periodic alternating gait trajectories, possibly even sinusoidal. In general, preferably, the honeycomb section includes polygonal cells, or meshes, or curved cells, or meshes, or straight cells, or meshes, or mixed cells, or meshes, as shown in Figs. 5a-5d.

[0042] Each of the walls 3, in each case, defines a profile 4.

[0043] Profile 4 is basically given by the outline of wall 3. In detail, profile 4 is given by the section on a plane of section 1b.

[0044] The plane of section 1 b is preferably perpendicular to the main plane 1 a.

[0045] In addition, the plane of section 1 b is also preferably perpendicular to the trajectories of development 3a.

[0046] Thus, profile 4 includes at least a first layer 40.

[0047] The first layer 40 is a portion of wall 3 identified by a portion of profile 4. Preferably the first layer (40) is made of aluminum or its alloy. For example, the first layer 40 may include aluminum alloys 1000, 2000, 3000, 5000, 6000, 7000.

[0048] In addition, profile 4 also includes at least a second layer 41.

[0049] Similar to the first layer 40, the second layer 41 is a portion of wall 3 identified by a portion of profile 4. Preferably the second layer 41 is made of aluminum or its alloy. For example, the first layer 40 may include aluminum alloys 1000, 2000, 3000, 5000, 6000, 7000.

[0050] In addition, first and second layers 40, 41 may be between 8 pm and 70 pm thick.

[0051] Profile 4 also includes a first separation layer 42.

[0052] The first separation layer 42 is placed between the first and second layers 40 and 41 . Thus, separation layer 42 is designed to separate layers 40, 41 . In this regard, preferably, the first separation layer 42 includes insulating material, appropriately an electrical type insulator.

[0053] For example, the material can be one or more of Polypropylene, PET polyethylene, including commercial Celgard®, glass fibers or cellulose.

[0054] In addition, preferably, the first separation layer 42 entirely covers, and thus entirely separates, at least the first electrode 40a of the first layer 40 and the second electrode 41 a of the second layer 41 .

[0055] Profile 4 also includes welding media 43.

[0056] Welding means 43 are arranged at opposite ends, relative to the main plane 1 a, of the first and second layers 40, 41 . Thus, welding means 43 are placed along the perimeter areas of walls 3.

[0057] In addition, welding means 43 are positioned to close the first separation layer 42 between layers 40, 41 and welding means 43.

[0058] For example, welding means 43 may include one or more of Polypropylene, Polyethylene, PET, Thermolacs or resins.

[0059] Profile 4 includes other features.

[0060] In particular, advantageously, the first layer 40 is coated, at one side facing the welding means 43, with a first electrode 40a.

[0061] The first electrode 40a is a choice between an anode and a cathode.

[0062] In particular, advantageously, the second layer 41 is coated, at one side facing the welding means 43, with a second electrode 41a.

[0063] Similar to the first electrode 40a, the second electrode 41a is a choice between an anode and a cathode. In the embodiments of Figs. 1 , 3 and 4, the second electrode 41 a is preferably different from the first electrode 40a. However, in the embodiment of Fig. 2, the second electrode 41 is the same as the first electrode 40.

[0064] Given the layered structure with coating, layers 40, 41 each simultaneously realize a collector, a barrier to the environment outside cell 1 , and a structural element.

[0065] The collector is given by each layer 40, 41 that creates an electrical connection with the outside. Also the barrier is given by each layer 40, 41 that protects from the outside the coating, that is, the electrodes, and more generally the inside of core 2. In addition, wall 3 is a structural element in that its own axial and bending strength determine the overall strength of the core.

[0066] In each case, core 2 further comprises an electrolyte 20.

[0067] Electrolyte 20 wets electrodes 40a, 41 a. Thus, electrolyte 20 is arranged between first layer 40 and first separation layer 42 and between second layer 41 and first separation layer 42. In any case, more generally, the electrolyte 20 is arranged close to the first layer 40 and the second layer 41 .

[0068] Of course, profile 4 could also include other layers.

[0069] For example, profile 4 could also include at least one intermediate layer 44.

[0070] If present, the intermediate layer 44 is placed between the first separation layer 42 and one between first and second layers 40, 41 . Of course, this does not imply that other elements cannot be present between intermediate layer 44 and first separation layer 42, or between intermediate layer 44 and first or second layers 40, 41 .

[0071] In any case, preferably, intermediate layer 44 is analogous to first and second layers 40, 41. Thus, the intermediate layer 44 including aluminum or its alloy. In addition, the intermediate layer 44 may be between 8 pm and 70 pm thick.

[0072] In addition, the intermediate layer 44 is coated with one or more between a third electrode 44a and a fourth electrode 44b. In detail, both the third electrode 44a and the fourth electrode 44b are a choice between an anode and a cathode. They may be of the same type, or different types. Third and fourth electrodes 44a, 44b preferably cover the intermediate layer 44 at opposite sides.

[0073] One or more of electrodes 40a, 41 a, 44a, 44b may include any battery electrode or super-capacitors, e.g. preferably, lithium or sodium battery electrode that can, indeed, be both anode and cathode.

[0074] In particular, the composition of electrode 40a, 41 a, 44a, 44b can include active material, additive and binder.

[0075] The active material, additive, and binder are to be considered constituents of the anode and cathode electrodes and are not necessarily present at the same time.

[0076] The type of active materials, additives and binders, may vary depending on whether you are considering anode or cathode of core 2. The role of active materials, additives and binders is respectively to exert energy storage function electrochemically, improve the electrical conductivity inside the electrode and impart structural coherence to the whole electrode. Structural consistency can mean both the effective adhesion of the electrode to layers 40, 41 and 44 and the maintenance of the constituent and structural properties during the fabrication and service life of the electrode.

[0077] Among the constituent components of the anode may be present as active materials, carbonaceous matrix materials, in weight percentages ranging from 0 to 100 percent. By carbonaceous matrix is meant a structure consisting of carbon in elemental percentages from 0 to 100%. Other constituent elements of the material may be nitrogen (N), oxygen (O), phosphorus (P), sulfur (S) silicon (Si), Tin (Sn) and other elements belonging to groups 13, 14, 15 and 16 and the transition metal series of the periodic system of elements. Included in this class of active materials are materials such as graphite-based active materials with purely crystalline structure, Hard Carbon-based active materials with mixed crystalline and amorphous structure, and Soft Carbon-based active materials with amorphous structure. Included in this category of materials are other crystalline materials with structural characteristics suitable for the storage of cations of the alkali and alkaline earth metals, such as oxides of the transition metals of the periodic system of elements and materials belonging to the class of transition metal isocyanates, generically referred to as "Prussian blue analogs." Size of the constituent particles of such materials falls in the 10 nm - 10 pm range. The above materials may have special carbon-based surface functionalizations designed to improve electrical conductivity characteristics.

[0078] Among the constituent components of the cathode may be present as active materials, materials belonging to the class of single-component oxides and multicomponent oxides of metals of the transition series of the periodic system of elements. Cathode active materials can also be poly-anionic materials, such as, but not limited to phosphates, fluorophosphates, vanadates, sulfates and pyrophosphates. Finally, cathode active materials can also be materials belonging to the class of transition metal isocyanates, generically referred to as "Prussian blue analogs." The above materials may be present in the form of particles with a size within the 10 nm to 10 pm range. The above materials may have special carbonbased surface functionalizations designed to improve electrical conductivity characteristics.

[0079] Anode and cathode electrodes can also include additives in their composition in weight percentages ranging from 0 to 50 percent. Materials classifiable as additives may be graphite-based materials with purely crystalline structure, Hard Carbonbased active materials with mixed crystalline and amorphous structure, and Soft Carbon-based active materials with amorphous structure. Size of the constituent particles of such materials falls in the 10 nm - 10 pm range.

[0080] Anode and cathode electrodes can also include binders in their composition in weight percentages ranging from 0 to 30 percent. Materials classifiable as binders are all polymeric or co-polymeric based materials, including in the non-exhaustive list, cellulosic-based polymers and co-polymers, polypropylene, polyethylene, polyvinyl, polyacrylates, polymethyl methacrylates, fluorinated or chlorinated compounds of the above, natural rubbers or synthetic rubbers, e.g., styrenebutadiene based.

[0081] The distribution density of electrode 40a, 41a, 44a, 44b on first or second layer 40, 41 or intermediate layer 44 is from 0.1 mg / cm2to 100 mg / cm2, more preferably between 5 mg / cm2and 30 mg / cm2.

[0082] Profile 4 may also include a second separation layer 45.

[0083] If present, the second separation layer 45 also including insulating material, similar to the first separation layer 42.

[0084] Thus, the second separation layer 45 is placed between the intermediate layer 44 and one between the first and second layers 40, 41 . Again, this does not imply that other elements cannot be present between second separation layer 45 and intermediate layer 44, or between second separation layer 45 and first or second layer 40, 41. For example, in fact, as in the three-cell embodiment of Fig. 3, the second separation layer 45 could be arranged between two intermediate layers 44. In any case, if there are intermediate layers 44 and second separation layers 45, the welding means 43 are arranged at opposite ends, relative to the main plane 1a, of the first, second 40, 41 and intermediate layers 44.

[0085] In general, welding means 43 can connect ends, or perimeter areas, of first and second layers 40, 41 , or first layer 40 and intermediate layer 44, or second layer 41 and intermediate layer 44, or two intermediate layers 44, to each other.

[0086] In general, welding means 43 allows the profile to close and seal electrodes 40a, 41 a, 44a, 44b, electrolyte 20 and first or second separation layer 42, 45 between welding means 43 and layers 40, 41 , 44.

[0087] Core 2 preferably also includes an interface layer 5.

[0088] If present, interface layer 5 is placed at each of the opposite ends, relative to the main plane 1 a, of profile 4.

[0089] In addition, interface layer 5 runs parallel to the main plane 1 a.

[0090] Preferably, interface layer 5 runs at least from the first layer 40 to the second layer 41 , that is, between the boundaries of profile 4.

[0091] Interface layer 5 preferably includes adhesive and / or insulating material.

[0092] Even more in detail, preferably interface layer 5 defines a mask shaped as the honeycomb section.

[0093] In particular, in fact, the interface layer 5 develops parallel to the main plane 1 a in such a way that it covers the walls 3 exactly along the respective development trajectories 3a.

[0094] Cell 1 may also include additional elements.

[0095] Preferably, cell 1 also includes a first skin 6 and a second skin 7.

[0096] If present, the first skin 6 runs parallel to the main plane 1 a. In addition, the first skin 6 is bound to one side of core 2.

[0097] The second skin 7, if present, runs parallel to the main plane 1 a.

[0098] Thus, the second skin 7 is bound to one side of core 2 opposite to the first skin 6. In this way, cell 1 forms a sandwich structure.

[0099] In even more detail, insulating layer 5 can be interposed between one or more skins 6, 7 and core 2. The latter can then act as a glue between skins 6, 7 and core 2.

[0100] Furthermore, in at least one embodiment shown in Fig. 4, the first layer 40 can be in contact with the first skin 6 such that the first skin 6 realizes a collector for the first electrode 40a.

[0101] Similarly, the second layer 41 can be in contact with the second skin 7 such that the second skin 7 makes a collector for the second electrode 41a.

[0102] The operation of the electrochemical pouch cell 1 for structural battery previously described in structural terms is similar to the operation of any electrochemical pouch cell.

[0103] However, the electrochemical pouch cell 1 for structural battery according to the invention achieves important advantages.

[0104] In fact, the electrochemical pouch cell 1 for structural battery provides high mechanical strength and, at the same time, high energy efficiency.

[0105] Thus, the electrochemical pouch cell 1 for structural battery is not subject to deformation during charging and discharging processes.

[0106] In addition, the electrochemical pouch cell 1 for structural battery is simple to fabricate, as standard commercial materials can be used to make the collectors, bonding, protective and structural layers.

[0107] In conclusion, an additional advantage of the electrochemical pouch cell 1 for structural battery lies in the increased reliability of the battery consisting of multiple cells 1 given the fact that each electrochemical cell is isolated from the others. That is, in case of impact or damage, only the affected cell 1 strips will stop working, while all others will not be affected by the damage and will continue to function normally. This is because each cell 1 is closed and independent of the others.

[0108] Variations may be made to the invention that fall within the scope of the inventive concept defined in the claims.

[0109] For example, first and / or second layer 40, 41 can be coated externally, that is, at the side opposite electrode 40a, 41 a, by a plastic protective layer.

[0110] In addition, one or more among the cells or meshes of the structure having a honeycomb section could internally include a filler. The filler could include structural material, preferably porous.

[0111] The porous material makes it possible, in detail, to reduce the overall weight of the filler. The filler may include one or more of polyurethane, polystyrene, or epoxy resins.

[0112] The advantage of including a filler in the honeycomb is twofold: on the one hand, it increases the structural strength of cell 1 , and on the other hand, it is useful in preventing deformation of cell 1 due, for example, to any gas buildup inside that may be generated during normal battery use due to electrolyte decomposition reactions.

[0113] In this context, all the details can be replaced by equivalent elements and any materials, shapes and dimensions can be used.

Claims

CLAI MS1. An electrochemical structural battery pouch cell (1 ) comprising- a core (2) developed along a main plane (1 a) and including a plurality of walls (3) developed perpendicularly to said main plane (1a) along respective development trajectories (3a) defined on said main plane (1 a) and formed in such a way that the coupling of said walls (3) realizes a structure having a honeycomb cross-section on said main plane (1 a),- each of said walls (3) defining a profile (4), on a plane of cross-section (1 b) perpendicular to said main plane (1a), and said development trajectories (3a), including at least- a first layer (40) of aluminum or its alloy- a second layer (41 ) of aluminum or its alloy- a first separation layer (42) arranged between said first and second layers (40, 41 ) and including insulating material, and- welding means (43) arranged at opposite ends, with respect to said main plane (1 a), of said first and said second layers (40, 41 ) so as to close said first separation layer (42) between said layers (40, 41 ) and said welding means (43); and characterised by the fact that- said first layer (40) is coated, in correspondence of a side facing said welding means (43), with a first electrode (40a) optionally between an anode and a cathode, and said second layer (41 ) is coated, in correspondence of a side facing said welding means (43), with a second electrode (41 a) optionally between an anode and a cathode in such a manner that said layers (40, 41 ) each simultaneously provide a collector, a barrier to the environment external to said cell (1 ) and astructural element, and- said core (2) further comprises an electrolyte (20) wetting said electrodes (40a, 41 a).

2. Cell (1 ) according to claim 1 , wherein said core (2) further comprises an interface layer (5) disposed at each of opposite ends, with respect to said main plane (1 a), of said profile (4) and developing parallel to said main plane (1a) from said first layer (40) and said second layer (41 ).

3. Cell (1 ) according to any preceding claim, wherein said interface layer (5) comprises adhesive and / or insulating material.

4. Cell (1 ) according to any one of claims 2-3, wherein said interface layer (5) defines a mask shaped as said honeycomb section parallel to said main plane (1a) so as to cover said walls (3) exactly along said respective development trajectories (3a).

5. Cell (1 ) according to any of the previous claims, wherein said profile (4) further comprising at least:- an intermediate layer (44) arranged said first separation layer (42) and one between said first and second layers (40, 41 ) and comprising aluminum or its alloy coated with one or more between a third electrode (44a) optionally between an anode and a cathode and a fourth electrode (44b) optionally between an anode and a cathode; and- a second separation layer (45) comprising insulating material and arranged between said intermediate layer (44) and one between said first and second layers (40, 41 ).

6. Cell (1 ) according to any of the previous claims, wherein said honeycomb section includes polygonal cells or curved cells or straight cells or mixed cells.

7. Cell (1 ) according to any of the previous claims, further comprising:- a first skin (6) developed parallel to said main plane (1 a) and bound to one side of said core (2), and- a second skin (7) extending parallel to said main plane (1 a) and constrained to a side of said core (2) opposite said first skin (6) so that said cell (1 ) forms a sandwich structure.

8. Cell (1 ) according to the preceding claim, wherein said skins (6, 7) are bonded to said core (2) by resins.

9. Cell (1 ) according to claim 7 and any one of claims 2-4, wherein between one or more of said skins (6, 7) and said core (2) is interposed said insulating layer (5).

10. Cell (1 ) according to claim 7, wherein said first layer (40) is in contact with said first skin (6) such that said first skin (6) realizes a collector for said first electrode (40a) and said second layer (41 ) is in contact with said second skin (7) such that said second skin (7) realizes a collector for said second electrode (41 a).

11. Cell (1 ) according to any of the previous claims, wherein said first layer (40) and / or said second layer (41 ) are externally coated, i.e. at a side opposite said electrode (40a, 41 a), by a plastic protective layer.

12. Cell (1 ) according to any of the previous claims, wherein one or more of said cells of said structure having a honeycomb cross-section includes internally a porous filler.

13. Battery comprising at least one cell (1 ) according to any of the previous claims.

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