Patent Publication Number: US-2021188128-A1

Title: Thermal management structure with integrated channels

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of International Application No. PCT/FR2019/052013 filed Sep. 2, 2019, which claims the benefit of priority to French Patent Application No. 1857878 filed Aug. 31, 2018, each of which is incorporated herein by reference in its entirety. 
    
    
     SUMMARY 
     The present invention concerns the field of thermal management. In particular, it concerns a thermal management device (also called a thermal barrier) designed to promote temperature management in an internal volume which this barrier surrounds or borders, on at least one side, and/or with respect to a temporary heat-producing element disposed therein. 
     This applies in particular, especially on a vehicle, to pipes, ducts or hoses in which fluids such as air or oil or a refrigerant (such as R1234 yf) circulate or electrical installations that heat, such as electric storage batteries, or engine parts whose temperature is to be managed:
         situations where a rapid rise in temperature must be encouraged, such as during a cold start,   situations where it is necessary to promote cooling of the said engine part, such as in subsequent stabilized operation.       

     In the present text will have the following meaning:
         PCM: a phase change material that changes its physical state (typically between liquid and solid) within a restricted temperature range, and absorbs up to a certain threshold a temperature change by storing the received energy; typically a temperature increase transmitted by a temperature rise of at least one cell,   thermal insulator: a material with a thermal conductivity 0.5 W/mK, which conducts heat less well than a PCM when it is in a phase where it is the least thermally conductive, and   thermally conductive: a material of thermal conductivity 1 W/mK.       

     As PCM, may be found:
         “hot” PCM(s) with a melting temperature between more than 22° C. and 38° C., and preferably between more than 25° C. and 37° C. This type of PCM may be used during summer rolling and in particular when the outside temperatures are above 40° C. By melting, the PCM stores the calories coming from outside and creates a first thermal barrier;   “cold” PCM(s) with a melting temperature between 14° C. and less than 26° C., and preferably between 15° C. and less than 25° C. This type of PCM may be used during winter driving, especially when temperatures are negative. By crystallizing, PCMs release calories that heat up the battery pack;   PCM(s) used, in direct thermal contact with the cells, typically an PCM with a precise melting temperature, typically 35° C., as one can seek to create a plateau over a range of temperatures currently considered high for the cells, in order to avoid thermal propagation between cells (buffer effect). In a battery, it may be very useful to be able to regulate the operating temperature of the cells that heat up when they produce current and that favorably must remain within a precise temperature range whatever the external temperature conditions are, even when the cells are at standstill. In an air pipe connecting two hot zones of an internal combustion engine, for example, the temperature in the internal volume of the pipe may have to be regulated.       

     In an engine crankcase, after a cold start phase, evacuating, or rather transferring calories may be useful. 
     In this context, it is therefore conceivable that it may be necessary, depending on the situation:
         to isolate from the outside environment or to manage the temperature evolution of an interior volume and/or its contents,   and/or to delay or on the contrary to favor the propagation of a thermal flow out of or towards this volume.       

     To circulate a fluid in a structure adapted to participate in this thermal management may then also be necessary. 
     Such structures exist which have fluid flow passages between two layers of material, between an inlet and an outlet for the fluid, so that a thermal insulation—if the layers are thermally insulating—or a thermal exchange—for example if the layers contain a PCM, the agreed name for a phase change material, PCM, with a change of state for example between liquid and solid—is achieved with respect to the fluid. 
     Thus, FR3015780 discloses the use of fluid channels in PCM for the circulation of a thermal transfer medium, especially liquid. The fluid channels are formed in a rigid block to hold them in place when the PCM changes to the liquid state. 
     This is a rather complex assembly to fabricate. In addition, there is no indication of how the shape of the PCM layers and the “rigid block” to hold the fluid channels in place may be achieved. 
     Thus, among the problems that we wanted to solve here is the one related to the efficient realization of the structures, or assemblies, adapted to participate in a thermal management of the environment. 
     A solution proposed here consists in a structure including at least one thermal management element comprising:
         a composite body containing at least one phase change material (PCM) in a rigid structuring matrix, so that the composite body is self-supporting regardless of the phase of the phase change material contained, the composite body being shaped to locally present externally at least one said cavity (viz. hollow) that defines by itself a channel wall suitable for the circulation of a fluid, the composite body defining a tray(viz. flat plate) which has a thickness (e) and on at least one of whose faces the channels formed by the cavities extend, and   between the channels, passages are formed in the thickness (e) of the flat tray to receive external elements to be placed in thermal exchange with the fluid to be circulated in the channels.       

     In this way, the interest (in weight, fineness and ease of shaping) of the composite body is combined with the realization of trays with integrated fluid circulation channels. 
     For the same purpose, it is also proposed a set of said structures comprising several structures as above in which said channels are arranged back to back, on two faces of each tray opposite each other according to thickness (e), the trays being stacked, one resting on the other between the channels of a same said face, so that a said tray forms a cover for the adjacent tray, thus creating said channels with a closed section. 
     A modular assembly is then produced whose shape and dimensions can be easily adapted to the number and dimensions of the cells in the battery. 
     The thickness (e) is then defined parallel to the stacking direction of the trays or, if each tray is plane, perpendicular to the plane of each tray. This also applies to an assembly comprising:
         the above assembly, in which the passages pass through the trays, and   as so-called external elements, cells of a vehicle electric battery arranged in the successive passages of the stacked trays.       

     The fact that this assembly may be such is also referred to:
         that the said cells are arranged in thermal exchange with the trays on the first sides of the cells, the channels being then connected to a first supply of fluid to be circulated in the said channels, and   that there is further included a cooling plate arranged in thermal exchange with the cells on second sides thereof, the cooling plate having ducts which are connected to a second supply of a fluid to be circulated in said ducts, for a surface thermal exchange with the cells.       

     The thermal management of the cells will be further strengthened, under other conditions, since the cooling plate will a priori be PCM-free. 
     Is as well concerned, the assembly:
         in which the cells, which are cylindrical, will extend in the successive passages of the stacked trays up to a base of each cell, and   where the cooling plate is arranged in thermal exchange with the cell bases. In the present solution, there are no fluid channels arranged in PCM (the channels are separated from the PCM by the material of the composite body). In fact, there is no longer any need for add-on structural elements to define the fluid channels themselves within a rigid intermediate structural element (which may also be dispensed with), nor is there any risk of altering the mechanical strength of the structure, which is self-supporting, if only because of the said cavities.       

     To all intents and purposes, it is confirmed that a phase-change material—or PCM—refers here to any material capable of changing its physical state, for example between solid and liquid or solid and gaseous, in a restricted temperature range between −50° C. and 50° C., or even between −60° C. and 150° C., taking into account the privileged applications which may occur in the field of vehicles (land, air, sea or river vehicles). Thermal transfer (or thermal transfer) may occur by using its Latent Heat (LC): the material can store or transfer energy by a simple change of state, while maintaining a substantially constant temperature, that of the change of state, 
     In connection with the use of a rigid structuring matrix, it was sought to define solutions that satisfy the following problem: industrial mass production, reduced mass, easy and precise cutting for shaping at will, low cost, thermal performance (adapted thermal conductivity, especially in a “battery” environment), maintenance of the phase change material (PCM) in the matrix during the phase change of the material, possible use in a fluid(s) exchanger system, with capacity for the PCM to be not in contact with the fluid(s), in order to avoid dispersions when it is in liquid phase (or gaseous in the event that it is in one of its phases). The contact (interface) with the fluid(s) will then be ensured by the rigid structuring matrix, 
     Taking this problem into account, it is first proposed that the composite structure should include an elastomer or fibers, thus in addition to at least one PCM (and a priori rather a material with several PCMs changing phases at different temperatures). With an elastomer, one will benefit from a high deformation capacity, while the fibers will be used for their lower density and their important capacity of impregnation of PCMs. 
     In the composite structure option including (at least) one elastomer, it is proposed that the elastomer be selected from the following compounds: NR, IR, NBR, XNBR, HNBR, ECO, EPDM, EPM, CM, CSM, ACSM, CR, ACM, EVA, EAM, ethylene-acrylic acid copolymers, butyl rubber, halogenated butyl rubber and isobutylene-p-methylstyrene para-bromo-methylstyrene, with the addition of at least one of the following modifying agents : carboxylic acid maleic anhydride-grafted 1,2-vinyl polybutadienes or epoxidized and/or hydroxylated polybutadienes, silanes, ethylene-acrylic acid copolymers, maleic anhydride-grafted ethylene-propylene copolymers. In this case, it will be a priori preferred that:
         the compactness should be between 60 and 100%.   the conductivity of the composite body be between 0.5 and 3 W/m.K-1, preferably between 1 and 2 W/m.K-1, and   the mass concentration in the composite body of the phase change material is between 40% and 70%, preferably between 50% and 60%. In the option composite structure including fibers, it is proposed that (at least) a graphite felt be used to take into account the above-mentioned problem.       

     In this case, it is preferable that the conductivity in the direction of the graphite fibres of the composite body be between 10 and 50 W/m.K-1, preferably between 20 and 40 W/m.K-1, and that the mass concentration in the composite body of the phase change material be between 20% and 95%, and preferably between 30% and 90%. 
     It should also be noted that the above-mentioned structures will be very useful for making protective housings or lining blocks. Thus, a housing comprising:
         several structures as above which will define the side walls of the case, and   blocks of angles each interposed between two said successive structures, which will bring them together and which will be crossed by communication passages between said cavities of the successive structures.       

     Another case: a housing comprising side walls and several structures as mentioned above which will double these side walls. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       If necessary, the invention will be better understood and other details, characteristics and advantages of the invention may appear when reading the following description made as a non-exhaustive example with reference to the appended drawings. 
       In these drawings: 
         FIG. 1  schematizes (in exploded view) structures conforming to those of the invention between and around a battery cell, to ensure peripheral thermal management; 
         FIGS. 2-5, 8, 10 and 12  show various examples of such structures conforming to those of the invention; 
         FIGS. 6, 7  schematize two local enlargements of the realization of  FIG. 5 ; and 
         FIGS. 9 and 11  schematize two local enlargements of the realizations of  FIGS. 8 and 10 , respectively, it being noted that  FIGS. 4 to 11  show operational structures, with joined elements, while  FIGS. 1 and 13 to 17  are exploded views; 
         FIG. 12  shows a composite body or so-called pocket, of curved shape; here with a roughly U- or C-shaped cross-section; 
         FIGS. 13, 14  show two solutions respectively with joints and additional tubes with liquid circulation, these two aspects may be dissociated; 
         FIGS. 15, 16  schematize two solutions with intermediate fluid circulation sheath; 
         FIG. 17  shows a solution with an intermediate plate for lateral closure of fluid circulation channels; 
         FIG. 18  shows a housing (viz. a casing) with two side panels incorporating fluid flow channels, 
         FIG. 19  (in three parts: top, right and left) and  FIG. 20  schematize a solution with stacked trays, passages for cells and air channels, 
         FIGS. 21, 22  show a combined and exploded thermal management assembly of prismatic battery cells with dual fluid flow, surface and core respectively, 
         FIG. 23  schematizes the solution shown in  FIG. 22 , with additional electrical insulation sheets, 
         FIGS. 24 to 28  refer to another embodiment in relation to cylindrical cells and cylindrical trays; a pullout in  FIG. 26  shows the inner composition of the PCM and some details about the passages, channels and cells (dotted lines);  FIG. 27  is a view from above and  FIG. 28  a side view; a pullout in  FIG. 27  shows some channels and cells. 
       In  FIG. 29  is illustrated an alternative embodiment in which the fluid inlet  87  and the fluid outlet  83  of the cavities  11  (including if the cavities are individually internally lined with a sheath  39 ) are located at a same end of the sheathes and are common on said sheathes, so that the sheaths are individually adapted so that the fluid flows back and forth in each sheath; see the arrows in  FIG. 29 . 
       
         25 
       
     
    
    
     DETAILED DESCRIPTION 
     A goal of the solution proposed here is thus the efficient realization of structures with high thermal inertia (related to the presence of PCM) and/or thermal insulation (related to the presence of PIV type thermal insulation) for environmental thermal management purposes, in particular for a battery of electric accumulators (also called “cells” in the present description). In fact, structure  1  proposed for this purpose includes, as illustrated:
         a composite body  3  containing at least one phase-change material  5  (PCM) dispersed in a rigid structuring matrix  7 , such that the composite body is self-supporting regardless of the phase of the phase-change material contained, and/or   a plastic or metallic, thermally conductive, gas-tight and under partial internal vacuum (PIV type) pouch  9 , having a shape maintained by the internal vacuum. Each pouch  9  (or  90  below) may wrap (i.e. contain) PCM  5 .       

     The composite body  3  and/or the pocket  9  are shaped to present locally at least one so-called cavity (viz.hollow)  11  which defines by itself a channel wall  13  which may be suitable, or even intended, for the circulation of a fluid  15 , it being then assumed that the channel created is then connected to a supply  17  and a recovery  19  of this fluid, which may be liquid or gaseous, see below:
           FIG. 4  for an example of circulation of fluid  15  in a closed circuit, with passage through an exchanger  20  where fluid  15  could either be charged with/either discharge calories or frigories, and     FIG. 8 , for an example of fluid flow  15  in an open circuit.       

     Fluid  15  may be either a thermal transfer medium or a refrigerant. It may be a liquid. 
     If, as shown in  FIG. 2-3 , structure  1  with the above-mentioned characteristics is limited to a composite body  3  or pocket  9 , the wall  13  of the channel (the cavity  11 ) can be closed off laterally, and the structure completed by at least one cover  21 :
         which will locally complete (itself) the wall  13 , via a part of its surface  21   a  placed against the composite body  3  or pocket  9 ,   and which will be attached to this composite body or pocket in a fluid-tight manner.       

     In the figures, the elements marked as composite body  3  or pocket  9  or lid  21  may be interchanged. 
     Thus, in an assembly or structure  1  provided with a cover  21 , at least one of the elements may be presented as a plate, without a so-called cavity, as shown in  FIGS. 5, 8, 10 . 
     For the connection with this cover, it is proposed that each composite body  3  or pocket  9  has lateral flanges  23  for a support of cover  21 . Lid  21  may then be welded to the composite body or pocket at the location of the flanges  23 . In this way, welding on the edges of the parts may be avoided, as shown in  FIG. 4.5 . 
     From the above, it is clear that any shape that serves as a cover for the fluid channel  15  is suitable. 
     However, for the construction of the covers, it may be preferable, as shown in  FIGS. 9,11 , that each cover  21  should include at least one cover:
         another self-supporting composite body  30  regardless of the phase of the PCM contained, and/or   another pocket  90 , PIV, plastic or metal, therefore gas-tight and under partial internal vacuum, whose shape will be maintained by the internal vacuum.       

     As previously, this other composite body  30  and/or other pocket  90  will then be shaped to locally complete and laterally close the wall  13  of the above-mentioned canal, viz. each cavity  11 . 
     As already mentioned, this will be an interesting answer to the current difficulties in the industrial production of a structure allowing both fluid circulation and packaging of either a vacuum or PCM. 
     In order to help achieve both a certain intrinsic stiffness and the definition of the desired fluid channels, it is further proposed that each composite body  3 . 30  or so-called pocket  9 . 90  should have, as illustrated:
         a curved shape, with angles  25  which may be rounded (see  FIG. 12 ); and/or,   a crenellated shape in which at least some of the crenellations  27  define several so-called cavities  11  (see  FIGS. 3,10  for example).       

     These slots and corners will also be well exploited by providing that, in order to laterally close each channel (i.e. each cavity  11 ), the cover  21  and the self-supporting composite body  3  or pocket  9 :
         have watertight welds between them, at the location of respective sections, such as  31   a,    31   b,  of walls bordering the channels,   and are in support two by two, including at the place of the said respective sections of walls, such as  31   a,    31   b,  thus interposed between two consecutive channels, or located on either side of the laterally external channels.       

     In pockets  9  or  90 , a so-called thermally insulating material (see above) may usefully be placed  29 , which may even reinforce the intrinsic strength of the vacuum pockets. 
     Concerning the choice in the realization of composite bodies  3 , 30 , the following recommendations may be followed, in particular to meet a need for temperature maintenance of cells or housings of a battery  33  of electric or hybrid vehicles; cf.  FIG. 1  where each structure  1  comprises in the example two parts  3 , 21  each directly integrating a series of channels (cavity  11  with walls  13 ), here parallel, of fluid circulation  15 , which arrives and leaves via an external circuit. 
     Indeed, lithium-ion cells in particular are strongly impacted by the temperature parameter. If this parameter is not taken into account, it may have serious consequences on the lifetime of the battery cells, on their performance (capacity and delivered power), on their stability and on the safety of use. 
     First of all, even if the liquid-gas and inverse change of state of PCMs is interesting in terms of the amount of energy involved, the preferred change of state in the targeted applications may be solid-liquid and inverse. Then, to stay with the example of lithium-ion cells, the temperature range in which they must be maintained to operate optimally is between 25 and 35° C. However, in addition to the materials used for the elements involved in the thermal management and the layering of these elements in layers that may combine PCM and thermal insulation (see for example WO2017153691), it may be necessary to provide for a fluid circulation within this architecture, typically between two layers of materials; see channel  55  in this document. 
     To be able to circulate a fluid  15 , with channels connected for example to an external air circuit, between the inlet/supply  17  and the outlet/recovery  19 , will then be required, in a structure such as that 1 presented here. 
     In addition to achieving this with the above solution, we also wanted to define a high-performance composite body, as mentioned above, since it is the very nature of this body that will ensure the criteria of thermal performance, self-supporting and ease of shaping or cutting expected. 
     Therefore, two solutions are proposed, respectively based on elastomer or fibers, each with several PCMs changing phases at different temperatures. It should be noted that the phase change materials used in the formulation will then be favorably formulated to include them in matrices with a mass quantity of PCM in the formulation typically between 30 and 95%. The formulations will preferably use microencapsulated or pure materials whose phase transitions may be included, for battery applications, between −10 and 110° C. (depending in particular on the electrochemistry, lithium-ion or not). 
     In the case of lithium-ion applications, microencapsulated PCMs with a mass percentage on formulated product of 35 to 45% may be used. These PCMs will be favorably included in a silicone matrix containing, in particular, flame-retardant and thermally conductive fillers. 
     In the first of the two above-mentioned solutions, matrix  7  includes (at least) an elastomer, which allows the body  3  to be adapted to situations that may require mechanical stressing or the monitoring of complex shapes (elastic aspect of the elastomer), with small masses. 
     In the second solution, the matrix  7  comprises fibers. 
     In terms of implementation, several structures  1  may be installed between two adjacent cells and/or on different faces and on the periphery of the battery compartment in order to wrap it. 
     Starting from the surface of the battery compartment, four layers of phase-change material (several PCMs) may be provided, between which fluid  15  (e.g. air) may be circulated. On the outside of the PCM cells, the vacuum insulation is installed, typically one or more pockets  9  or  90 . A thermally conductive peripheral envelope will allow the mechanical strength and protection of the system as a whole. 
     Note that the above two solutions ensure that the PCM is not in direct contact with the fluid and that there is no leakage of PCM in the fluid state. In general, a composite body solution as above will be able to work dynamically: on an electric or hybrid vehicle, typically at a time of high demand, such as for example during a start under electric drive in winter (outside temperature of 3-4° C. for example) we will indeed be able to circulate air (coming from the outside) in the cavities which will allow this air to heat the PCM, having in passing recovered thermal energy on the cells of the battery, the air may then be redirected to the outside environment. During its journey, the air will have both warmed the PCM(s) and evacuated excess heat from the battery cells. Another hypothesis: in winter, during cell operation, air cooled by an air conditioning circuit is projected towards the cells. This blown air then passes in channels  11 . 
     Now, concerning the fabrication of the 3.30 composite bodies, it should be noted that they may be presented as plates comprising compressed fibrous graphite as a structuring matrix in which the PCM, which may be, or comprise, kerosene (viz. paraffin), is impregnated. 
     Graphite felts can be obtained by exfoliation. If there is a cover, it will be thermally conductive (e.g. plastic foil). The impregnated matrix will not release PCM if it is not stressed. And to obtain a composite body with an integrated channel wall, the raw composite body may simply be molded or machined. The vacuum bag solution may be obtained by folding. 
       FIG. 13 , one solution proposes that structure  1 , which comprises composite body  3  and lid  21  with at least one other so-called composite body  30 , additionally includes grooves  35  in composite body  3  and/or lid  21 . The grooves  35  receive seals  37  for fluid tightness between said bodies, bordering the cavities  11 . In the example, the fluid  15  is in direct contact with the channel walls  13 . 
     The alternative solution in  FIG. 14  proposes that structure  1  includes tubes  39  for the circulation of a liquid, as fluid  15 . The tubes  39  are individually received in the opposing cavities  11 . They are made of a material that promotes thermal exchange with the interior of the elements  3 , 9 , 21  so that this takes place as the fluid passes through. 
     The alternative solution in  FIGS. 15,16  proposes that structure  1  include a sheath  41  for circulation of said fluid  15 . Sheath  41  has an inlet  43  and an outlet  45  for the fluid. It incorporates several elongated depressions (viz recesses)  47  protruding outwards. These depressions  47  are received (wedged) in the opposing cavities  11 . The sleeve  41  is fixed directly or not (e.g. by gluing together panels  21  and  3  (or  9 ) on either side of the sleeve) between lid  21  and the composite body or said pocket. Transversally to a general direction  49  of elongation of the depressions  47 , and thus of the cavities  11 :
         the sheath  41  occupies a closed section  51  (see section defined by the bold line in  FIGS. 15,16 ) of between 30 and 100% of the cumulative section of said lid  21  and composite body or pocket (see hatched sections S 2   a  and S 2   b  in  FIGS. 15,16 ), and   in this closed section  51 , the depressions  47  occupy a minor section, preferably between 5 and 20% of the said total section  51  of the sheath (see hatching in the sheath  FIG. 15 ). The sheath is made of a material that promotes thermal exchange with the interior of the elements  3 , 9 , 21  so that this takes place when the fluid passes in and circulates throughout the sheath (section  51 ).       

     Elongated depressions  47  may be on both large surfaces of the sheath if both panels or structures  3  or  9  and  21  are provided with cavities  11  ( FIG. 15 ), or on one surface only if only one of the structures  3  or  9  and  21  is provided with cavities  11  ( FIG. 16 ). 
     The advantage of a sheath compared to a solution with independent tubes or plate  51 , as shown in  FIG. 14 or 17 , may be a security seal; it is also no longer necessary for cover  21  to be fixed together with the composite body ( 3 ) or pocket ( 9 ) in a fluid-tight manner. In the sheath solution, a grouped arrangement, self-centering and a fluid passage cross section  15  not limited to the hollow areas may be used (the entire cross section S 1  is concerned, not only that of the depressions  47 ). 
     The alternative solution in  FIG. 17  proposes that structure  1  should include a plate  51  for lateral closure of the cavities  11  and thus of the channel walls  13 . The plate  51 , which is flat and solid, is fluid-tightly interposed between the at least one cover  21  and the composite body  3  (or the said pocket  9 ). If both lid  21  and composite body  3  (or said pocket  9 ) had cavities  11 , plate  51  could allow two different fluids  15  to flow on either side of the plate into the respective cavities  11 . If there are tubes  39  for circulation of a liquid, as said fluid  15 , the tubes  39  are individually received in the opposing cavities  11 . They are made of a material that promotes thermal exchange with the inside of the elements  3 , 9 , 21  so that this takes place when the fluid passes in. 
       FIG. 18  shows a solution with a box  53  in which at least some of the side walls, three adjacent  55   a,    55   b,    55   c  in the example, are doubled, here externally, by side panels  1  integrating (walls of) channels  13  for fluid circulation and blocks  57  of fluid connection angles between two channels of adjacent panels. The arrows mark the inlets and outlets of fluid  15 , respectively from and to a source, as shown in  FIG. 1 . In the examples in  FIGS. 1 and 18 , the corner blocks  57  are arranged at the corners, between two adjacent side panels, or structures,  1  arranged to form an angle between them and which the side walls  57   a,    57   b  of each corner block  57  allow to join. For the circulation of the fluid, each corner block  57  integrates ducts  59  to be connected individually to the channels  11  facing it. Each duct  59  is curved so that the fluid flows through the corresponding corner. Preferably, each corner block  57  should be made of thermal-insulating material (e.g. PU foam). 
     In an application such as a battery  33 , where thermal management may involve both part of a whole (one cell of the battery) and the whole (all cells of the battery), cell  33 . 53  of the above solutions shown in conjunction with  FIGS. 1 and 18  may involve both one cell and all of the cells. In the latter case, the side panels, or structures,  1  would surround all the cells, which would not prevent each cell from being surrounded by another group of side panels, or structures,  1  supplied with fluid, which may or may not be the same as the aforementioned  15 . 
     It should also be noted that cover  21  or the other element of a panel, or structure,  1  to body  3  or pocket  9  may include a thermal insulating material that is not under partial internal vacuum (PU foam, for example), and therefore not PIV (see  FIG. 1 ). 
       FIGS. 19,20  also show two variants of a structure  1  conforming to the invention which comprises a series of said composite bodies  3  and/or pockets  9  each defining a tray  63  (viz. flat plate), in two versions  63   a  ( FIG. 19 ) or  63   b  ( FIG. 20 ). 
     The objective is to produce an assembly allowing cooling, for example by forced air, of vehicle battery cells  64 , by favouring their thermal management in their optimal operating temperature range, avoiding dead zones and non-homogeneous temperatures. 
     To this end, each tray  63  has a thickness (e) and on at least one of the faces  630 , channels formed by the aforementioned cavities  11 . These channels extend along the entire length of the face concerned and open individually on two opposite sides of the tray. 
     In addition, between the channels  11 , passages  65  are formed in the thickness (e) of the tray  63  to receive external elements  67  (in this case the cells  64 ) to be placed in thermal exchange with the fluid  15  to be circulated in the channels  11 . Thus, the external elements  64 ,  67  to be stored are stored transversely to the plane P of each tray and the flow of fluid  15  circulates in this plane, over the largest possible surface. 
     Each tray may thus be defined by a molded PCM element integrating passages  65  and channels  11 , which makes assembly easy (left view,  FIG. 19 ), integration of the fluid channels (top view,  FIG. 19 ) and easy selection of the PCM phase change close to the operating temperature of the cells. 
     Typically, if the cells  64  are presented as a kind of “cylindrical stack” as illustrated, each tubular in shape, the trays will be favorably stacked, parallel and leaning against each other between channels  11  on the same side, so that one said tray  63  forms a cover for the adjacent tray  63 , thus creating said channels with a closed section. 
     In order to increase thermal exchange, it is recommended that tray  63  include channels  11  arranged back to back, on the two opposite sides  630 ,  631  according to the thickness (e) of each tray. 
     And for the positioning and holding of cells  64 , the passages  65  pass through the entire thickness (e) of the trays  63  and the cells  64  are individually arranged in the successive passages  65  of these stacked trays  63  through which they pass. A lower support plate  69  can support the stack and the cells  64 . It may be a cooling plate with other channels  71  for the circulation of coolant, in thermal exchange with each cell  64 , at its base  64 a; right view  FIG. 19  and  FIG. 20 . 
     In the version of  FIG. 20 , channels  11  are all parallel to each other. In the version of  FIG. 19 , channels  11  extend in several directions ( 71   a,    71   b ) so as to cross each other and are staggered in one of the directions (viz. in quincunx), that of  71   b  in the example (top view of  FIG. 19 ). 
     In connection with a solution shown in  FIGS. 19 to 22 , another aspect of the invention aims at ensuring a particularly fine and efficient thermal management of a vehicle electric battery, such as that  33  of  FIG. 1 , or that of  FIG. 19  with its cylindrical cells, or that  33 ′ of  FIGS. 21, 22  with its prismatic cells (here rectangular)  64 ′, aligned in at least one direction to form a rectangular parallelepiped of square or rectangular section. 
     If WO2017153691 raises the subject, the solution could be improved. Thus it is first proposed here as an improved solution, as  FIGS. 21, 22, 27, 28 , an assembly including :
         several structures  1  as already presented, with all or part of their characteristics, and thus individually with composite body  3  or pocket  9  or lid  21 ,   several electric battery cells  64 ′ of a vehicle, and   a said cooling plate  69  arranged in thermal exchange with the cells  64 ′ on said second sides  643  of the latter.       

     The cooling plate  69  is thermally conductive and has ducts (here internal)  71  which are connected to a second supply  73  of a fluid to be circulated in said ducts  71 , for a surface thermal exchange with the cells  64 ′. On this subject, it should be noted that this is also provided for in the solution of  FIGS. 19,20  and  FIGS. 24-28 . This thermal exchange is called “surface thermal exchange” because the cooling plate  69  is against an outer boundary face of the battery. It is not between two cells, as is the housing with structure  1 . In the design selected, each cell and the battery as a whole is supported by cooling plate  69 . 
     In addition, in this solution, between two first opposite sides (respectively  641   a  and  641   b,    FIG. 22 ) of at least two successive cells  64 ′, there is a space  75  where at least one structure ( 1 ;  3 ,  9 ,  21 ) is interposed, in thermal exchange with the cells, with its channel-forming cavities  11  that are connected to a first supply  77  of a fluid to be circulated in said channels  11 , in the heart of the space  75 , between the cells  64 ′. The first and second fluids, respectively of the supplies  77 ,  73 , do not cross each other; their circulations are independent; hence the possibility of two different fluids; see  FIGS. 21 and 24-28 . 
     If  FIG. 22  clearly shows space  75 , because of the exploded view, each space is, once the assembly is completed, occupied by at least one structure  1 . The structures ( 1 ;  3 ,  9 ,  21 ) and cells  64 ′ are placed one against the other, in a stacking direction (here horizontal). In the selected mode of construction, each space  75  is occupied, from one cell to the next, by two structures  1 , a thermal insulating block  79 , then two more structures  1 . 
     The second fluid supply  73  will usefully be that of a liquid, such as water, because the sealing and connections are simpler to ensure than for the first supply  77 . In addition, this will be more effective when there is “surface thermal exchange”. This second fluid supply  73  will also be usefully connected in a closed (looped) circuit, via a pump  81 ;  FIG. 21 . 
     After exiting (in  83   FIG. 21  or  FIGS. 24-26 ) from the said assembly, the conduits of the said first supply  77  may, via a conduit  85  and adapted valves, be looped to the inlet  87 , to ensure a recycling of the fluid, even if this means passing it in a thermal exchanger  89 , in particular to blow at certain times into the channels  11  a fluid cold enough to make the PCMs return to the solid state, in a hypothesis of PCMs with two phases: solid and liquid. 
     Even if not represented in  FIG. 21 , a thermal exchanger referenced  101  in  FIGS. 27-28  may be disposed on such a closed circuit conduit  85 , to adapt the temperature of the fluid supplied to the ducts  71  by the so-called second fluid supply  73 . 
     The second fluid supply  73  will usefully use a gaseous fluid, such as air. It is preferable that the circulation of this fluid in the assembly be forced (fan or other). 
     Once again, for a quality of thermal exchange and a well-considered optimization of the thermal management provided by these fluid circulations, in connection with the PCMs present, it is recommended that each composite body ( 3 ) or pocket ( 9 ) presents, in front of the cells  64 ′ (but this may also apply for example to the cells  64  of the previous solution), a solid, continuous surface  645  for non-discrete thermal exchanges with the cells. It will have been understood that, on the contrary, a discrete contact is like separate zones without a continuum. 
     Thus, in the previous solution, the surfaces  645  were formed by solid cylindrical faces. In the solution of  FIGS. 21,22 , surfaces  645  are flat, as are the walls  641   a  and  641   b  of the cells opposite. Thus, one may foresee that in front of one of said cells ( 64  or  64 ′ for example) each composite body ( 3 ) or pocket ( 9 ) is applied in surface contact against the cell, without ventilated (forced) circulation of fluid between them. 
     Crossing the flows of the first and second fluids (always without mixing them) could further improve the efficiency of thermal exchanges. 
     Moreover, to counter the thermal transfers of a so-called  64 ′ cell, it is proposed in the solution for prismatic cells ( FIGS. 21, 22 ), to interpose a thermal insulating block  79  between two composite bodies ( 3 ) or pockets ( 9 ) themselves thus interposed between two so-called  64 ′ cells. 
     In the solution in  FIG. 23 , which reproduces the characteristics of the previous solution ( FIGS. 21,22 ), electrical insulation sheets  91  were added, each interposed between one structure  1  and one cell  64 ′. 
     The purpose of the electrical insulation sheets  91  is to avoid short circuits in the event that the PCM of the composite bodies ( 3 ) or pockets ( 9 ) is electrically conductive. It is not obligatory to install this component, depending on the characteristics of the PCM but also on the desired effect: electrical insulation desired or not. 
     If the electrical insulation sheets  91  are provided, it will be advantageous for the effectiveness of the electrical insulation that the contact surfaces between the elements  1 ,  91 ,  64 ′ are flat and continuous; hence the advice of flat surfaces on the two opposite sides of the electrical insulation sheets  91  and on the side of structure  1  (composite body  3  or pocket  9 ) facing the adjacent electrical insulation sheet  91 ; see  FIG. 23 . 
     In the additional embodiment of  FIG. 24  is one more time illustrated an assembly comprising electric cells  64 ′ of an electric battery, a fluid inlet  87 , a fluid outlet  83 , and one of a plurality of composite bodies  3 . 
     The fluid supply (called first supply)  77  may comprise a fan or a compressor or a pump, and a buffer tank. 
     As in the solution of  FIG. 21 , the fluid outlet  83  may be connected to the outside environment (atmospheric pressure), or include, as previously explained, a closed-loop recycling circuit  85  (see the dotted line in  FIG. 24 ) for recycling at least a part of the fluid  15  from the outlets of tubes  11  to the inlets thereof. 
     In conformity with the previous embodiments, each structure comprises at least one thermal management element  1  comprising a composite body  3  containing at least one PCM  5  disposed in a rigid structuring matrix  7 , such that the composite body is self-supporting regardless of the phase of the PCM contained. 
     The, or each, composite body  3  is shaped to locally present externally (means in fluid connection with outside) cavities  11  which each defines by itself a wall  13  of a channel suitable for circulating a fluid. 
     The, or each, composite body  3  defines a tray (see for example  FIG. 26 ) which has a thickness (e) and opposite faces on at least one of which extend the channels  11 : (at least some of) the channels  11  open on the opposite faces  330 ,  331  of the tray they pass through. 
     Between the channels, passages  65  are formed in the thickness (e) of the tray to receive external elements  64 ′ to be placed in thermal exchange with the fluid  15  to be circulated in the channels  11 . 
     Thus, the composite bodies  3  are individually shaped into layers, such as  3   a,    3   b;  five layers for example. 
     Each layer, such as  3   a,    3   b,  may be defined by one of said composite bodies  3 . As previously, the composite bodies individually are molded composite bodies, preferably. 
     The layers or trays may be stacked, successively one on top of the other. They may be so arranged, along the same direction Z as the cells  64 ′ from their respective bases  64   a  (bottoms) to their tops  64   b  where the anode  640   a  and cathode  640   b  are located. 
     Each cell  64 ′ may be cylindrical and elongated from bottom to top. 
     The layers, such as  3   a,    3   b:  
         are arranged face to face, so as to form a unitary block.   individually have passages  65  therethrough in which the electric cells  64 ′ are respectively arranged, one per passage, and,   individually further have channels  11  therethrough.       

     Superposing the layers, such as  3   a,    3   b  is a solution, as illustrated. Each passage  65  preferably has a closed bottom  66 . 
     At the opposite, at the top, the anode  640   a  and cathode  640   b  are accessible from outside the corresponding composite body  3 , to be electrically connected. 
     The channels  11  are suitable to circulate a fluid  15  therein. 
     The channels  11  have respective fluid inlets  110   a  commonly connected to the (external) fluid inlet  87  and respective fluid outlets  110   b  commonly connected to the (external) fluid outlet  83 . 
     The PCM  5  is in thermal exchange with the electric cells  64 ′ arranged in the passages  65  and with the fluid  15  which circulates in the channels  11 , in accordance with the vehicle mode of operation. 
     Fluid  15  may be a gas or liquid, such as air or an water-based liquid (means more than 50 wt % of water). 
     The layers, such as  3   a,    3   b,  individually have a thickness e according to the Z direction. 
     Preferably, the passages  65  and the channels  11  are arranged in a common direction. 
     Preferably, said layers are arranged face to face according to the Z direction, and both the passages  65  and the channels  11  pass through the layers transverse to said Z direction (vertically in the example). 
     If so arranged, parallel to the passages  65 , the channels, or cavities,  11  will open each on the opposite faces  330 ,  331 . 
     Two by two, adjacent layers, such as  3   a,    3   b,  are applied one against the other, or bordered by seals for preventing fluid  15  from leaking, especially if liquid. 
     Individually arranging a sheath  39  ( FIG. 25 ) within said cavities channels, or cavities,  11  will allow fluid  15  to circulate in the thermal management element  1 . Each sheath  39  has an inlet  39   a  and an outlet  39   b  for the fluid. Each sheath  39  may be a tube. 
     To get an electric battery pack, a plurality of composite bodies  3  are grouped, side to side ( FIGS. 27-28 ), each containing the cells  64 ′, and all the ducts  11  thereof are commonly connected to the respective fluid inlet  87  and fluid outlet  83 , even if  FIGS. 26-27  show, as partial examples, only two ducts  11  connected to the respective inlet  87  and fluid outlet  83 , while  FIG. 28  shows more of such connections of ducts  11 , and  FIG. 24  shows one connection only. 
       FIGS. 26-27  show and confirm other advantageous details of this embodiment explained in relation to  FIGS. 24-28 :
         the set of trays/layers/composite elements comprises both the passages  65  passing through the stacked trays and said cells  64 ′ of a vehicle electric battery individually arranged in the passages  65 ,   the cells  64 ′ are arranged in thermal exchange with the trays on first sides of the cells; lateral convex side  64   c  of each cell in the example,   the channels  11  are connected to the first supply  77  of fluid  15  to be circulated in said channels,   a cooling plate  69  is arranged in thermal exchange with the cells on second sides  64   a  thereof, and   the cooling plate having ducts  71  which are connected to a second supply  73  of a fluid (which may be a liquid) to be circulated in said ducts  71 , for a thermal exchange with the cells.       

     The cooling plate, with a series of ducts  71  passing therein, in the plane of the cooling plate, may extend under the electric battery pack and the thermal management elements  1 . 
     In other words:
         with cylindrical cells  64 ′ extending, through the successive passages  65  of the stacked trays, from the first side  64   b  of each cell, where the anode and the cathode are located, up to said second side  64   a  (bottom or base) of each cell,   the cooling plate  69  will be arranged in thermal exchange with the bases  64   a  of the cells  64 ′.       

     In  FIG. 29  is illustrated an alternative embodiment in which the fluid inlet  87  and the fluid outlet  83  of the cavities  11  (including if the cavities are individually internally lined with a sheath  39 ) are located at a same end of the sheathes and are common on said sheathes, so that the sheaths are individually adapted so that the fluid flows back and forth in each sheath; see the arrows in  FIG. 29 . 
     In other words, each cavity  11  (or sheath  39 ) is adapted so that the fluid  15  flows back and forth through said common fluid inlet  87  and fluid outlet  83 : each cavity  11  (or sheath  39 ) will have an opening at one end and a closed wall at the opposite end. 
     The (open) end of each cavity  11  (or sheath  39 ), where the commonly formed fluid inlet  87  and fluid outlet  83  is located, will preferably be the bottom end, so that, if liquid, the fluid  15  circulating in the respective cavities will flow back by gravity. 
     Neither cavity  11  nor sheath  39  has any fluid communication with the ducts  71  in the cooling plate  69 . They are physically separated. 
     Fluid circulating in the (ducts of the) cooling plate  69  has no communication with fluid  15  circulating in each cavity  11  (or sheath  39 ). Preferably, these respective fluids will have no thermal exchange therebetween.