A Structural Battery

Abstract

A structural battery (10) for delivering electric power to an application requiring electric power comprising: a container (12) of a first material; and a core (30) for a plurality of electric cells (34,134) provided within said container (12) wherein the container (12) and the core (30) of the composite structure (10) together form a structural member having resistance to shear forces, compression forces, tension forces, torsional forces and longitudinal and transverse bending forces imposed on said structural member by the application and wherein said core (30) comprises a means for controlling temperature (141, 150, 152, 250) of said core (30), preferably within a predetermined temperature range.

Claims

1. A structural battery for delivering electric power to an application requiring electric power comprising: a container of a first material; and a core for a plurality of electric cells provided within said container wherein the container and the core of the composite structure together form a structural member having resistance to shear forces, compression forces, tension forces, torsional forces and longitudinal and transverse bending forces imposed on said structural member by the application and wherein said core comprises temperature control means for controlling temperature of said core, preferably within a predetermined temperature range.

2. The structural battery of claim 1, wherein the predetermined temperature range for the structural battery is between 0 C. to 50 C., preferably 15 C. to 35 C.

3. The structural battery of claim 1 wherein the temperature control means includes a heat absorbing material located within the core.

4. The structural battery of claim 3 wherein the heat absorbing material is arranged throughout the core as elements or units, optionally of a material that changes state or phase, the change of state or phase requiring sufficient heat to prevent thermal runaway.

5. The structural battery of claim 1 wherein said temperature control means includes a heat exchanger system that includes first heat exchanger(s) to add or remove heat from the core so that core temperature or battery operating temperature is maintained within the predetermined temperature range.

6. The structural battery of claim 5 wherein said first heat exchanger operates through heat transfer to and from a heat transfer fluid, wherein a controller controls heat transfer fluid flow rate to reduce error between a target battery operating temperature and sensed temperature depending on battery operating conditions.

7. The structural battery of claim 6 wherein said heat exchanger system includes second heat exchanger(s) to add or remove heat from the heat transfer fluid enabling recirculation for temperature control.

8. The structural battery of claim 1 wherein the core accommodates the electric cells within one or more spaces pre-formed in a material or a sub-structure resistant to compression and shear loads as well as temperature, a portion of the material or sub-structure being made thermally conductive to assist heat transfer and temperature control.

9. The structural battery of claim 8, wherein said core structure is formed by a framework of core elements or layers, optionally forming a honeycomb structure, the core elements including fluid passage means through which heat transfer fluid flows to enable heat transfer to or from the electric cells, and their accommodating spaces, to or from the heat transfer fluid.

10. The structural battery of claim 9, wherein said core elements are electrically and thermally conductive.

11. The structural battery of claim 9, wherein the core elements are laminated sheets.

12. The structural battery of claim 11 wherein the laminated sheets are corrugated to accommodate electric cells.

13. The structural battery of claim 11 wherein a plurality of parallel disposed fluid passage means extend through said sheet core elements.

14. The structural battery of claim 11 wherein laminated sheet layers are spaced apart by elongate insulating spacers, preferably having dogbone shape and comprising arcuate or concave surfaces for neatly accommodating electric cells.

15. The structural battery of claim 14 wherein said insulating spacers are intumescent for enabling phase change cooling.

16. The structural battery of claim 14 wherein said insulating spacers comprise high shear strength polymeric material.

17. An electric device comprising a composite structure as claimed in claim 1 as a structural member within said electric device.

18. The device of claim 17 selected from the group consisting of portable devices, mobility devices and electric vehicles.

19. A method of temperature control in an electric vehicle comprising at least one structural battery comprising: a container of a first material; and a core for a plurality of electric cells provided within said container wherein the container and the core of the composite structure together form a structural member of the electric vehicle having resistance to shear forces, compression forces, tension forces, torsional forces and longitudinal and transverse bending forces imposed on said structural member by vehicle operation and wherein said core comprises a means for controlling temperature of said core, preferably within a predetermined temperature range, and further comprising the step of controlling temperature during a vehicle operating condition selected from the group consisting of harsh acceleration, crashing or piercing.

20. The structural battery of claim 2 wherein the temperature control means includes a heat absorbing material located within the core.

21. The structural battery of claim 3 wherein said temperature control means includes a heat exchanger system that includes first heat exchanger(s) to add or remove heat from the core so that core temperature or battery operating temperature is maintained within the predetermined temperature range.

22. The structural battery of claim 4 wherein said temperature control means includes a heat exchanger system that includes first heat exchanger(s) to add or remove heat from the core so that core temperature or battery operating temperature is maintained within the predetermined temperature range.

23. The structural battery of claim 10, wherein the core elements are laminated sheets.

24. The structural battery of claim 12, wherein a plurality of parallel disposed fluid passage means extend through said sheet core elements.

25. The structural battery of claim 12, wherein laminated sheet layers are spaced apart by elongate insulating spacers, preferably having dogbone shape and comprising arcuate or concave surfaces for neatly accommodating electric cells.

26. The structural battery of claim 13, wherein laminated sheet layers are spaced apart by elongate insulating spacers, preferably having dogbone shape and comprising arcuate or concave surfaces for neatly accommodating electric cells.

27. The structural battery of claim 15, wherein said insulating spacers comprise high shear strength polymeric material.

Description

[0022] The composite structure of the invention may be more fully understood from the following description of exemplary embodiments thereof made with reference to the drawings in which:

[0023] FIG. 1 shows an orthogonal cutaway view of a structural battery including a temperature control means according to one embodiment of the present invention.

[0024] FIG. 2 shows a plan view of the core structure of FIG. 1.

[0025] FIG. 3 shows a detail view of a core element of the core structure of FIGS. 1 and 2.

[0026] FIG. 4 shows an insulating spacer from the core structure as shown in FIGS. 1 and 2.

[0027] Referring now to FIGS. 1 and 2, there is shown a cutaway view of a structural battery 10 for delivering electric power to an application requiring electric power such as an electric motor vehicle (not shown) but not limited to this. Structural battery 10 includes a container 12 of a first, fibre reinforced composite material such as CFRP; and a core 130 of a second material for accommodating a plurality of electric cells 134 provided within the container 12. The first material may also include other materials resistant to longitudinal and transverse bending forces, preferably lightweight materials which may include light metals or metal alloys such as aluminium alloys. Container 12 includes respective upper and lower facing layers 12a and 12b (which though shown curved would typically be flat in practice) of sufficient strength to treat tension and compression loads. Facing layers 12a and 12b are of CFRP. The structural battery 10 therefore has a composite sandwich structure.

[0028] The structural battery 10 forms a structural member having resistance to compressive, shear and longitudinal and transverse bending forces imposed on the structural member by the electric motor vehicle whether stationary or in operation. Further description of the structural battery 10 and its composite sandwich structure, which approximates an I beam in structural characteristics, is provided in the Applicant's co-pending International Application filed 8 Aug. 2018 under Attorney Docket No. P42453PCAU, incorporated herein by reference.

[0029] Structure 130 forms the core of the structural battery 10. Core structure 130, which is intended to be resistant to compressive and shear loads, is also electrically and thermally conductive comprising a framework of core elements 131 of laminated lightweight structure comprising multiple corrugated aluminium sheets or layers 131AA and 131AB which are bonded together with a laminated structure in a corrugation moulding process in such a way as to leave generally cylindrical spaces 132 of circular section for accommodating electric cells 134 and connecting tabs or electrodes 135 and 136 in a manner avoiding short circuiting and other electrical malfunctions. One electric cell 134 is accommodated by each space 132. Electric cells 134 are desirably close packed within the core structure 130, desirably with a packing factor approaching that for hexagonal geometry.

[0030] Layers 131A and 131B are spaced apart by elongate insulating spacers 141 which also serve as structural links assisting in the provision of compressive strength and shear resistance. Insulating spacers 141, one of which is shown in detail in FIG. 4, have arcuate or concave surfaces 141A and 141 B and a dogbone shape when viewed end on or in plan. Such insulating spacers 141, having the requisite compatible shape, are included as blanks and may facilitate corrugation moulding. A polymeric insulating material, such as polyamide, may be used for spacers 141. The spacer material may be intumescent. Spacers 141 may also include information links, such as a thermistor 141C, for sensing battery parameters such as battery operating temperature.

[0031] Referring further to core structure 130 as shown in FIGS. 1 and 2, the layers 131 are formed of second thermally and electrically conductive material, aluminium or copper, these layers 131including layers or sheets 131A and 131Bbeing separated by elongate insulating spacers 141 with arcuate or concave surfaces 141A and 141B and having a dogbone shape when viewed end on or in plan as shown in FIG. 4. The dimensions of concave surfaces 141A and 141B are selected to neatly accommodate electric cells 134. The insulating material can be included as blanks for corrugation moulding, forming the dogbone shaped spacers 141 during fabrication. A ceramic or polymeric insulating material, such as polyamide, may be used. An intumescent material may be used to enable phase change cooling. A high shear strength material may also be selected. A material with strong adhesive properties such as epoxy resin could also be selected with or without fillers to enhance the aforesaid properties. Spacers 141 may also include information links and sensors, such as thermistors, for sensing battery parameters such as temperature.

[0032] The number of electric cells 134 and number of spaces 132 selected to accommodate such electric cells 134 is determined with reference to the electric power requirements of the application. Further description is included in the Applicant's co-pending International Patent Application filed under Attorney Docket No. P42453PCAU, incorporated herein by reference. Many, perhaps thousands of, electric cells 34 (134) may be required for the application.

[0033] Electric cells 134 of various types could be selected and this is not critical though suitable batteries could be selected from rechargeable batteries especially from the lithium ion battery class, such as for example 18650 or 2170 type batteries which have a cylindrical geometry and are rated at 3.7 v per cell. In the case of an electric motor vehicle, the selected electrical cells 134 would enable the structural battery 10, while having the required structural properties to act as a structural member, to have a relatively shallow depth in relation to length and breadth.

[0034] Electrical connections between the electric cells 134 are described in the Applicant's co-pending International Patent Application filed 8 Aug. 2017 under Attorney Docket No. P42682PCAU, the contents of which are incorporated herein by reference. The plurality of interconnected electric cells 134 generate heat during operation creating a risk of overheating, inefficient operation and damage to or failure of structural battery 10. Temperature control is required.

[0035] To that end, the temperature within the structural battery 10 and particularly within its core structure 130 is controlled by a heat exchanger system 250 to maintain structural battery operating temperature within acceptable limits, for example 15 C. to 35 C. Heat exchanger systems 250 operate through heat exchange between the electric cells 134 and honeycomb structure 130 and a heat transfer fluid selected not to interfere with battery 10 operation, here a refrigerant or ethylene glycol, is circulated so that heat generated by the electric cells 134 is absorbed and the structural battery 10 cooled to maintain operating temperature within the acceptable limits.

[0036] Referring again to FIG. 2 and core structure 130, electrical connections are made between electric cells 134, accommodated within circular spaces 132 formed by the corrugated layers 131 of core structure 130. Each electric cell 134 is, through positive and negative electrodes 135 and 136, connected to negative and positive terminals of other electric cells 134 within the honeycomb structure 130 to provide both series and parallel connections providing the required voltage and capacity requirements for the battery application. Further description is included in the Applicant's co-pending International Patent Application filed 8 Aug. 2018 under Attorney Docket P42682PCAU, the contents of which are incorporated herein by reference. Heat is generated by the impedance of electric cells within the core structure 130 and so structural battery 10 requires thermal control to maintain operating temperature within a desired temperature range, again 15 C. to 35 C. In some cases, battery heating may be necessaryfor example under cold ambient conditionsand the temperature control system enables this.

[0037] Core elements 131 are comprised of corrugated aluminium sheets 131AA and 131AB which are bonded in a laminate structure through are separated by insulating spacers 157 (for example of ceramic material) included during fabrication. However, to enable battery 10 cooling, the insulating spacers 157 do not extend the full length of layers 131A and 131B, rather leaving inter-connected galleries 150 and 152, forming part of first heat exchanger 100, through which heat transfer fluid, such as a refrigerant, is circulated by fixed or variable speed pump P during battery operation. The interconnected galleries 150 and 152 form a first heat exchanger of heat exchanger system 250. This enables battery temperature to be controlled. Direction of heat transfer fluid flow as driven by pump P is indicated by arrows C in FIG. 3. Heat transfer fluid is directed first through galleries 150 and returns, following the heat transfer process, through return galleries 152. The galleries 150 and 152 can also transport heat transfer fluid to heat the structural battery 10 if required under cold ambient conditions.

[0038] Refrigerant warms during the cooling process and to remove this heat, where required, heat exchanger system 250 includes a second heat exchanger 200 to enable heat exchange between the refrigerant and air or other medium. The second heat exchanger 200 could take the form of a finned heat exchanger, chiller or radiator. The refrigerant can then be recirculated through the heat exchanger system 250 to galleries 150, 152 and the heat transfer process continues in this manner. Again, if battery 10 requires heating, the cooled heat transfer fluid can be reheated in suitably configured second heat exchanger 200.

[0039] The heat exchanger system 250 described above includes suitably rated first and second heat exchangers 100 and 200 to control the temperature of the core 130 and maintain the structural battery 10 at acceptable operating temperature. That is, heat output (or heat requirement) from the interconnected electric cells 134 can be calculated allowing, with consideration of other relevant parameters, estimation of the battery operating temperature under particular conditions. First heat exchanger 100 may then be designed to control the required structural battery operating temperature within acceptable limits. Required heat transfer fluid flow (C) rates can be calculated and the pump P selected. The second heat exchanger 200 can also be designed in similar manner. Heat transfer fluid flow C may be controlled by a suitable electronic control unit through controlling speed of variable speed pumps P dependent on structural battery 10 temperature, as sensed by information links as described above and, for example, embedded in insulating spacers 141 for core structure 130. Heat exchangers 100 and 200 can also be configured to enable structural battery heating, for example under cold ambient conditions.

[0040] As described above, the structural battery 10 can be used in a range of applications including in fixed structures, mobility devices and portability devices. A potential application is to electric motor vehicles. In such case, a bank of structural batteries 10 could accommodate a very large number of electric cells 134, potentially thousands, and form a floor pan for an the electric motor vehicle. Weight, which is significantly lower than that involved with conventional metal and metal alloy battery containers or trays, would then be focused in the lowest point of the vehicle where one or a bank of structural batteries provides a load bearing beam between front and rear wheels, left and right wheels (where provided) and a torsionally rigid member between all wheels.

[0041] Structural battery 10 is rechargeable and not intended for replacement under normal circumstances. However, it could be made replaceable if desired. This itself could depend on the application.

[0042] Modifications and variations to the structural battery described herein may be apparent to the skilled reader of this disclosure. Such modifications and variations are deemed within the scope of the present invention.