Storage cell for an electrical energy storage device with cell-internal heating and battery for a motor vehicle

Description

[0001] The present invention relates to a cell for electrochemically storing electrical energy and a battery comprising such a cell.

[0002] The performance of lithium-ion cells is temperature-dependent. The temperature dependence of performance is particularly pronounced for cells with high energy densities or manganese-rich cell chemistry, or when using solid electrolytes. The available power decreases at low cell temperatures. Cell charging is also highly temperature-dependent. For rapid charging, the cell temperature should be greater than 20°C. To increase the performance of lithium-ion cells operating at low temperatures, they are heated with a heating device located near the cells to be heated. If a large number of lithium-ion cells are heated by a single heating device, it takes a long time for all cells, across their entire cell volume, to reach their operating temperature.Although the time until all cells reach operating temperature can be shortened by increasing the heating temperature of the heater, this also increases the risk of thermal runaway, especially for cells with high energy density.

[0003] JP 201224319 A describes an energy storage device in which a heat-insulating element, which may have a cooling element, is arranged between adjacent storage cells.

[0004] The present invention is therefore based on the object of providing a cell for the electrochemical storage of electrical energy in which heating to its operating temperature is improved and the risk of thermal runaway of the cell (due to the heating itself and otherwise) is minimized. Furthermore, the spread of thermal runaway from one cell to a neighboring cell, and thus the risk of thermal runaway propagation to all cells of a battery, is to be minimized.

[0005] This object is achieved according to the teaching of claim 1. Various embodiments and developments of the invention are the subject of the subclaims.

[0006] It is a further object of the present invention to provide a battery in which heating to its operating temperature is improved and the risk of thermal runaway and potential propagation thereof is minimized.

[0007] The solution to this problem is achieved according to the teaching of claim 12.

[0008] The present invention is also based on the object of providing a vehicle that quickly reaches its full performance even at low temperatures and is safe.

[0009] The solution to this problem is achieved according to the teaching of claim 14.

[0010] A first aspect of the invention relates to a cell for electrochemically storing electrical energy, comprising: a first subcell and a second subcell, each configured to electrochemically store electrical energy; and a first insulating body for thermally insulating the first subcell and the second subcell from one another, which first insulating body is arranged in a space between the first and second subcells delimited by a side surface of the first subcell and a side surface of the second subcell, wherein the first insulating body comprises a first thermally insulating material with a thermal conductivity of at most 1 W / (m·K) and a first heating structure configured to heat the first subcell and the second subcell, and wherein the first insulating body is electrically insulated from both the first subcell and the second subcell. Preferably, the first thermally insulating material is also flame-retardant.

[0011] This allows the cell to heat up more quickly and reduces the risk of thermal runaway.

[0012] A subcell can be designed as a cell stack or a cell wrap (jelly roll). A subcell can be a lithium-ion cell. Examples of thermal insulation materials that can be used include fiberglass, Kevlar, and mica.

[0013] For the purposes of the present invention, thermal conductivity is understood as the inverse of the specific thermal resistance. The thermal conductivity (λ) of a thermal insulation body, the heat flux density (dq / dt) through the thermal insulation body, and the temperature difference (degrees T), which is the cause of the heat flow, are related as follows: dq / dt = -λ·degrees T. The unit of measurement for thermal conductivity is W / (m·K) (watts per meter times Kelvin).

[0014] For the purposes of the present invention, the thermal mass (C) or heat capacity of a body, e.g., a subcell, is the ratio between the heat supplied to it (dQ) and the resulting temperature increase (dT): C = dQ / dT. The unit of measurement for thermal mass is J / K (Joule per Kelvin).

[0015] As used herein, the terms "comprises," "includes," "includes," "has," "has," "with," or any other variation thereof are intended to cover non-exclusive inclusion. For example, a method or apparatus that includes or has a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or that are inherent in such a method or apparatus.

[0016] Furthermore, unless explicitly stated otherwise, "or" refers to an inclusive "or" and not an exclusive "or." For example, a condition A or B is satisfied by one of the following conditions: A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), and both A and B are true (or present).

[0017] The terms "a" or "an" as used herein are defined as "one or more." The terms "another" and "another," and any other variations thereof, are defined as "at least one other."

[0018] Preferred embodiments of the first aspect of the invention and further developments thereof are described below, which can each be combined with one another as well as with the other aspects of the invention described, unless this is expressly excluded or is technically impossible.

[0019] In a preferred embodiment, the first thermally insulating material has a thermal conductivity of less than 0.3 W / (m·K). This minimizes the risk of thermal runaway of the cell.

[0020] The first heating structure has two heating elements.

[0021] Furthermore, the first thermally insulating material is formed as a plate having a first surface and a second surface opposite the first surface, the first surface and the second surface each face one of the side surfaces of the first and second subcells delimiting the intermediate space, and a heating element of the first heating structure is arranged on the first surface and the second surface.

[0022] This allows the heating temperature of each of the heating elements to be reduced to such an extent that the risk of thermal runaway of the cell caused by heating with the heating elements is eliminated. The heating temperature of a heating element is the temperature to which it must be heated in order to raise the temperature of the subcell it heats to the (optimal) operating temperature. The heating temperature can be, for example, 70 °C. Each of the two heating elements can be designed as a (meander-shaped) resistive track. This resistive track can comprise one of the following materials or a combination of these: aluminum, nickel, copper, graphene-silver, or silver paste as a printed conductor.

[0023] In a preferred embodiment, the heating element arranged on the first surface covers at least 50% of the first surface; and / or the heating element arranged on the second surface covers at least 50% of the second surface.

[0024] This allows the portion of the space defined by the two subcells that has a thermal resistance exceeding the thermal resistance of the first thermally insulating material to be increased, thus further reducing the risk of thermal runaway of the cell. The portion of the thermal resistance that exceeds the thermal resistance of the first thermally insulating material is formed by at least one of the heating elements.

[0025] In a preferred embodiment, each location on the first surface not covered by the heating element arranged on the first surface corresponds to an opposite location on the second surface that is covered by at least a portion of the heating element arranged on the second surface.

[0026] This allows each point of the space defined by the two subcells to have a thermal resistance that exceeds the thermal resistance of the first thermally insulating material, thus further reducing the risk of thermal runaway of the cell.

[0027] In a preferred embodiment, at least the heating element arranged on the first surface comprises aluminum.

[0028] This allows the heating element to be implemented cost-effectively and its share of the total thermal resistance between the first and second subcell to be increased.

[0029] In a preferred embodiment, the first subcell and the second subcell each have a thermal mass, and the thermal masses of the first and second subcells differ from each other by no more than 5% of the lower of the two thermal masses. Preferably, the thermal masses of the first and second subcells differ from each other by no more than 1% of the lower of the two thermal masses.

[0030] This allows both subcells to be heated to the same degree and a symmetrical temperature distribution in the subcells relative to the insulation body can be achieved.

[0031] A preferred embodiment further comprises: a third subcell configured to electrochemically store electrical energy, and a second insulating body for thermally insulating the second subcell and the third subcell from one another, said second insulating body being arranged in a space between the second and the third subcell defined by a side surface of the second subcell and a side surface of the third subcell, wherein the second insulating body comprises a second thermally insulating material having a thermal conductivity of at most 1 W / (m·K) and a second heating structure configured to heat the second subcell and the third subcell, and wherein the second electrically insulating body is electrically insulated from both the second subcell and the third subcell. Preferably, the second thermally insulating material is also flame-retardant.

[0032] This allows the energy stored in the cell to be increased, the cell to be heated up more quickly and the risk of thermal runaway to be reduced.

[0033] In a preferred embodiment, the second thermally insulating material has a thermal conductivity of less than 0.3 W / (m·K). This minimizes the risk of thermal runaway of the cell.

[0034] The second thermally insulating material can be formed as a plate. This plate can have two opposing surfaces. The surfaces can each face one of the side surfaces of the second and third subcells that define the gap. The second heating structure can have two heating elements, each arranged on one of the opposing surfaces. Furthermore, a heating element can cover at least 50% of the surface on which it is arranged. Also, each point on a surface that is not covered by the heating element arranged on this surface can correspond to an opposite point on the other surface that is covered by at least part of the heating element arranged on this surface. At least one of the heating elements of the second heating structure can comprise aluminum.

[0035] Alternatively, the second thermally insulating material may be formed from two plates, and the second heating structure comprises a heating element arranged at least partially between these two plates.

[0036] In a preferred embodiment, the first subcell and the third subcell each have a thermal mass, the thermal masses of the first and third subcells differ from each other by no more than 5% of the lower of the two thermal masses; and the second subcell has a thermal mass that differs from each other by no more than 5% of twice the thermal mass of the third subcell. Preferably, the thermal masses of the first and third subcells differ from each other by no more than 1% of the lower of the two thermal masses; and / or the second subcell has a thermal mass that differs from each other by no more than 1% of twice the thermal mass of the third subcell.

[0037] This allows all three subcells to be heated to the same intensity and an essentially homogeneous temperature distribution in the subcells can be achieved.

[0038] In a preferred embodiment, the first insulating body and the second insulating body have the same design.

[0039] This allows the cell to be built efficiently and cost-effectively.

[0040] In a preferred embodiment, the first subcell and the second subcell each comprise: a first electrode, a second electrode having a higher electrical potential than the first electrode, and a separator arranged between the two electrodes; the first insulating body is enclosed on all sides by an electrolyte-stable film, with the exception of one or more electrical connections connected to the first heating structure; the electrolyte-stable film simultaneously electrically insulates the first insulating body from the first subcell and from the second subcell; and the first subcell, the second subcell, and the part of the first insulating body arranged in the space between the first and second subcells and enclosed by the electrolyte-stable film are immersed in a liquid electrolyte. The electrolyte-stable film can comprise: Kapton, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PP (polypropylene), PE (polyethylene).

[0041] As a result, a cell having a liquid electrolyte can be heated internally (i.e. by the heating structure provided in the first and / or second insulating body).

[0042] In a preferred embodiment, the first subcell and the second subcell each comprise: a first electrode, a second electrode having a higher electrical potential than the first electrode, and a solid electrolyte arranged between the two electrodes.

[0043] This allows a cell to be heated with a solid-state electrolyte.

[0044] In a preferred embodiment, the first thermally insulating material further exhibits one of the following properties or a combination thereof: compressible, elastic, flame-retardant according to DIN 4102-1. The second thermally insulating material can also exhibit one of these properties or a combination thereof.

[0045] This allows the insulation body to absorb the bulging of the subcells during charging or discharging processes, particularly elastically. The thermally insulating material can also retain its thermal insulation properties for a long time, even when overheated.

[0046] A second aspect of the invention relates to a battery comprising a cell according to the invention.

[0047] The features and advantages explained with respect to the first aspect of the invention also apply accordingly to the second aspect of the invention.

[0048] A third aspect of the invention relates to a vehicle comprising a battery according to the invention.

[0049] This makes it possible to provide a vehicle, especially one with an electric drive, that quickly reaches its full performance even at low temperatures and is safe.

[0050] Further advantages, features and possible applications of the present invention will become apparent from the following detailed description in conjunction with the figures.

[0051] This shows Fig. 1a schematically shows a cell for electrochemically storing electrical energy according to a first embodiment; Fig. 1b schematically shows the internal structure of an insulating body for thermal insulation and heating of two subcells of a cell; Fig. 1c schematically shows a heating element provided in an insulating body for heating two subcells; Fig. 2 schematically shows the internal structure of another insulating body for thermal insulation and heating of two subcells; and Fig. 3 schematically shows a cell for electrochemically storing electrical energy according to a second embodiment.

[0052] The Figure 1aschematically shows a cell 100 for electrochemically storing electrical energy according to a first embodiment. The cell 100 comprises: a subcell 101 and a subcell 102, each designed for electrochemically storing electrical energy; and an insulating body 103 for thermally insulating the subcell 101 and the subcell 102 from one another. The insulating body 103 is arranged in a space between the subcells 101 and 102, delimited by a side surface 111 of the subcell 101 and a side surface 112 of the subcell 102. In order to prevent thermal runaway from spreading from one subcell to the other or at least to delay it for a sufficiently long time, the insulating body 103 comprises a thermally insulating material with a thermal conductivity of at most 1.0 W / (m·K). Preferably, the thermal conductivity of the thermally insulating material is less than 0.3 W / (m·K).The thermally insulating material may include fiberglass, Kevlar, or mica. Furthermore, the insulating body 103 is electrically insulated from both subcell 101 and subcell 102.

[0053] The insulating body 103 is further configured to heat the subcell 101 and the subcell 102. For this purpose, it has a heating structure with two electrical connections 113 and 114, via which the heating structure can be connected to a power source. To heat the subcells, the heating structure is connected to the power source, and the heat generated in the heating structure is transferred to the subcells adjacent to the insulating body essentially by thermal conduction. The heating structure and / or the power source are configured such that, when heating the subcells, the temperature of the heating structure (heating temperature) is limited to a predetermined value. This predetermined value is dimensioned, on the one hand, to prevent overheating of one of the two subcells 101 and 102 (which could trigger thermal runaway in the overheated subcell), and, on the other hand, to heat the two subcells 101 and 102 to their optimal operating temperature as quickly as possible.

[0054] The Figure 1bshows a schematic section through the insulating body 103 in a plane that is perpendicular to the side surfaces 111 and 112 (defining the gap) and passes through the electrical connection 113. According to this figure, i) the thermally insulating and flame-retardant material is formed as a plate 105, which has a surface 115 and a surface 116 opposite it; ii) the heating structure has two heating elements 107 and 108, each arranged on one of the opposite surfaces 115 and 116; and iii) the plate and the heating structure, with the exception of the electrical connections, are covered with an electrically insulating film 120. The heating elements 107 and 108 can be connected to a power source via the electrical connections and can be connected in series or parallel. The plate 105 is preferably cuboid-shaped. The electrically insulating film 120 is electrolyte resistant and can contain: Kapton, PET, PEN, PP, PE.

[0055] The Figure 1c shows a top view of surface 115. It shows a meandering arrangement of heating element 107 on surface 115, its connection to electrical terminal 113, and an electrical connecting line 117, which (in the case of a series connection) connects heating element 107 to heating element 108 arranged on surface 116. Heating element 108 can also be arranged in a meandering pattern on surface 116 and is connected to electrical terminal 114. This is not shown in the figures. A heating element can comprise nickel, copper, aluminum, graphene-silver, or silver paste as a printed conductor.

[0056] Advantageously, the heating element 107 covers at least 50% of the surface 115 and / or the heating element 108 covers at least 50% of the surface 116. Furthermore, it is advantageous if the (meandering) course of the heating elements 107 and 108 is selected such that each point on the surface 115 not covered by the heating element 107 corresponds to an opposite point on the surface 116 that is covered by at least part of the heating element 108. This allows the thermal conductivity of the insulating body 103 to be further reduced.

[0057] In cell 100, surface 115 faces side surface 111, so that heating element 107 is located closer to subcell 101 than to subcell 102. Furthermore, the thermal resistance from heating element 107 to subcell 102 due to thermally insulating plate 105 is significantly higher than the thermal resistance from heating element 107 to subcell 101. All of this results in the heat generated by heating element 107 spreading predominantly toward subcell 101 and contributing to its heating. Similarly, the heat generated by heating element 108 spreading predominantly toward subcell 102 and contributing predominantly to its heating. The temperature to which each of heating elements 107 and 108 must be heated to bring subcells 101 and 102 to their optimal operating temperature can be reduced to 70°C or lower.At this temperature, thermal runaway caused by the heating elements is not to be expected.

[0058] The heat generated by heating element 107 when heating cell 100 therefore essentially corresponds to the heat required to heat subcell 101 to the optimal operating temperature. Similarly, the heat generated by heating element 108 essentially corresponds to the heat required to heat subcell 102 to the optimal operating temperature. Advantageously, the thermal masses (heat capacities) of subcells 101 and 102 are equal. Then, with the same heating power of heating elements 107 and 108, a symmetrical temperature distribution relative to the insulation body and essentially uniform heating of the cell can be achieved.

[0059] The subcells of a cell are, for example, lithium-ion cells and can be configured as cell stacks or cell wraps (jelly rolls). For example, subcells 101 and 102 can be configured: both as cell stacks, both as cell wraps, one as a cell stack and the other as a cell wrap. Furthermore, each subcell of a cell has: a first electrode, a second electrode having a higher electrical potential than the first electrode, and a separator or a solid-state electrolyte arranged between the two electrodes. In the case of a cell with a liquid electrolyte, the foil enclosing the thermally insulating material and the heating structure is also electrolyte-stable.

[0060] A modification of the first embodiment, which does not have all the features of the invention, can be achieved by replacing the insulating body 103 with another one, Figure 2This can be achieved by the insulating body 203 shown schematically. The insulating body 203 also comprises a thermally insulating material with a thermal conductivity of at most 1.0 W / (m·K) and is electrically insulated from the subcells. Preferably, the thermal conductivity of the thermally insulating material is less than 0.3 W / (m·K). The thermally insulating material can comprise: fiberglass, Kevlar, mica.

[0061] The insulating body 203 is designed to heat the subcells adjacent to it and has a heating structure with two electrical connections 213. To heat the subcells, the heating structure is connected to a power source, and the heat generated in the heating structure is transferred to the subcells essentially by thermal conduction. The heating temperature is limited to a predetermined value to prevent overheating of the cell.

[0062] The Figure 2shows a section through the insulating body 203 in a plane perpendicular to the plane containing the heating structure and passing through one of the electrical connections 213. The thermally insulating material of the insulating body 203 is formed from two parallel, opposing, shear-flammable plates 205 and 206, and the heating structure has a heating element 207 arranged between the two plates. The plates 205 and 206 and the heating structure, with the exception of the electrical connections 213, are covered with an electrically insulating and electrolyte-stable foil 220. Each of the plates 205 and 206 has two opposing, parallel surfaces: the plate 205 has surfaces 215 and 221, and the plate 206 has surfaces 216 and 222. The heating element 207 is arranged on one of the surfaces 221 or 222, for example, as shown in the Figure 1cHeating element 107 shown. Advantageously, heating element 207 covers at least 50% of the surface and / or comprises at least one of the following: nickel, copper, aluminum, graphene-silver, or silver paste as a printed conductor. Plates 205 and 206 are preferably cuboid-shaped and / or have the same design.

[0063] A cell according to the modified first embodiment—not shown in the figures—therefore comprises: a first subcell and a second subcell, each configured for electrochemically storing electrical energy; and the insulating body 203 for thermally insulating the first subcell and the second subcell, which is arranged in a space between the first and second subcells defined by a side surface of the first subcell and a side surface of the second subcell. Surface 215 faces the side surface of the first subcell defining the space, and surface 216 faces the side surface of the second subcell defining the space.

[0064] Because in a cell according to the modified first embodiment, a thermally insulating plate is located between the heating element 207 and the subcells, the heating temperature of the heating element 207 is higher than that of the heating elements of the insulating body 103. A comparable rapid and reliable heating of the subcells with the insulating body 103 can be achieved with the insulating body 203 if its heating temperature is in a range between 120 °C and 150 °C.

[0065] Advantageously, the thermal masses of the first subcell and the second subcell are equal. This allows for essentially uniform heating.

[0066] The Figure 3schematically shows a cell 300 for electrochemically storing electrical energy according to a second embodiment. The cell 300 has: a subcell 301, a subcell 302, and a subcell 303, each configured for electrochemically storing electrical energy; an insulating body 304 for thermally insulating the subcell 301 and the subcell 302 from one another; and an insulating body 306 for thermally insulating the subcell 302 and the subcell 303 from one another. The insulating body 304 is arranged in a space between the subcells 301 and 302, which space is delimited by a side surface 311 of the subcell 301 and a side surface 312 of the subcell 302. and the insulating body 306 is arranged in a space between the subcells 302 and 303, which space is delimited by a side surface 321 of the subcell 302 and a side surface 322 of the subcell 303.The insulating bodies 304 and 306 are electrically insulated from the subcells and each have electrical connections 313 and 314, via which they can be connected to a power source. Each of the insulating bodies 304 and 306 is configured like one of the insulating bodies 103 or 203. Therefore, their structure will not be discussed further. The insulating bodies 304 and 306 can have the same design, in particular, be of the same construction.

[0067] Advantageously, the thermal masses of subcell 301 and subcell 303 are equal, and subcell 302 has a thermal mass twice that of one of subcells 301 and 303. With the same heating power of the heating structures integrated into the insulation body, a substantially uniform heating of subcells 301, 302, and 303 can then be realized.

[0068] A cell according to the third embodiment—not shown in the figures—comprises: n subcells, where n is a natural number, each configured to electrochemically store electrical energy; and n-1 insulating bodies, electrically insulated from the n subcells and each configured like one of the insulating bodies 103 or 203. Each k-th insulating body, where k assumes natural values ​​between 1 and n-1, is provided for thermally insulating the k-th subcell and the k+1-th subcell and is arranged in a space between the k-th and the k+1-th subcell, delimited by a side surface of the k-th subcell and a side surface of the k+1-th subcell. The n-1 insulating bodies preferably have the same design.

[0069] Advantageously, the thermal masses of the first and nth subcells differ from each other by no more than 5%, preferably 1%, of the lower of the thermal masses of the first and nth subcells, the thermal masses of all other subcells (i.e., the second, the third, ..., and the (n-1)th subcell) differ from each other by no more than 5%, preferably 1%, of the lower of the thermal masses of the other subcells, and the thermal masses of the other subcells each differ from each other by no more than 5%, preferably 1%, of twice the thermal mass of the lower of the thermal masses of the first and nth subcells. Preferably, the thermal masses of the first and nth subcells are the same, the thermal masses of all other subcells (i.e., the second, the third, ..., and the (n-1)th subcell) are the same, and the thermal masses of the other subcells are each twice the thermal mass of the first or nth subcell.With the same heating power of the n-1 heating elements, an essentially uniform heating of the n subcells can be achieved.

[0070] Advantageously, the thermally insulating material from which plate 105 or plates 205 and 206 are formed is sufficiently compressible to accommodate the bulging of the subcells. Furthermore, it is advantageous if the thermally insulating material is flame-retardant (e.g., according to DIN 4102-1).

[0071] While at least one exemplary embodiment has been described above, it should be appreciated that a wide variety of variations exist. It should also be understood that the described exemplary embodiments are merely non-limiting examples and are not intended to limit the scope, applicability, or configuration of the devices and methods described herein. Rather, the foregoing description will provide one skilled in the art with guidance for implementing at least one exemplary embodiment, it being understood that various changes in the operation and arrangement of the elements described in an exemplary embodiment may be made without departing from the subject matter as defined in the appended claims, as well as their legal equivalents. LIST OF REFERENCE SYMBOLS

[0072] 100 Cell 101, 102 Subcells 103 Insulating body 105 Thermally insulating material (plate) 107, 108 Heating elements of a heating structure 111, 112 Side surfaces of two adjacent subcells that define the space between these two subcells 113, 114 Electrical connections 115, 116 Surfaces of the thermally insulating material 117 Electrical connection 120, 220 Electrically insulating and electrolyte-stable foil 203 Insulating body 205, 206 Thermally insulating and flame-resistant plates 207 Heating element of another heating structure 213 Electrical connections 215, 221 Surfaces of a thermally insulating plate 216, 222 Surfaces of another thermally insulating plate 300 Cell 301...303Subcells 304, 306Insulating bodies 311, 312Side surfaces of two adjacent subcells that define the space between these two subcells 313, 314Electrical connections 321, 322Side surfaces of two other adjacent subcells that define the space between these two subcells.

Claims

1. Cell for electrochemically storing electrical energy, comprising: a first subcell (101; 301) and a second subcell (102; 302), which are each designed for electrochemically storing electrical energy; and a first electrolyte-stable insulating body (103; 304) for thermally insulating the first subcell and the second subcell from each other, said body being arranged in an interspace between the first and second subcells that is confined by a side face (111; 311) of the first subcell and a side face (112; 312) of the second subcell, wherein the first insulating body comprises a first thermally insulating material (105; 205, 206) having a thermal conductivity of at most 1 W / (m·K) and comprises a first heating structure which is designed to heat the first subcell (101; 301) and the second subcell (102; 302), wherein the first insulating body is electrically insulated both from the first subcell and from the second subcell, wherein the first heating structure comprises two heating elements (107, 108), the first thermally insulating material (105) is designed as a plate which has a first surface (115) and a second surface (116) opposite the first surface, the first surface and the second surface each face one of the interspace-confining side faces of the first and second subcells, and a heating element (107, 108) of the first heating structure is arranged on each of the first surface (115) and the second surface (116).

2. Cell according to Claim 1, wherein the heating element arranged on the first surface (115) covers at least 50% of the first surface; or the heating element arranged on the second surface (116) covers at least 50% of the second surface.

3. Cell according to Claim 2, wherein each point on the first surface (115) which is not covered by the heating element (107) arranged on the first surface has a corresponding opposite point on the second surface (116) which is covered by at least part of the heating element (108) arranged on the second surface.

4. Cell according to any of the preceding claims, wherein at least the heating element (107) arranged on the first surface (115) comprises aluminium.

5. Cell according to any of the preceding claims, wherein the first subcell (101) and the second subcell (102) each have a thermal mass, and the thermal masses of the first and second subcells differ from each other by not more than 5%, preferably 1%, of the lesser of the two thermal masses.

6. Cell according to any of Claims 1 to 4, further comprising: a third subcell (303) which is designed for electrochemically storing electrical energy; and a second insulating body (306) for thermally insulating the second subcell (302) and the third subcell (303) from each other, said body being arranged in an interspace between the second and third subcells that is confined by a side face (321) of the second subcell and a side face (322) of the third subcell, wherein the second insulating body (306) comprises a second thermally insulating material (105; 205, 206) having a thermal conductivity of at most 1.0 W / (m·K) and comprises a second heating structure which is designed to heat the second subcell (302) and the third subcell (303), and wherein the second electrical insulating body (306) is electrically insulated both from the second subcell (302) and from the third subcell (303).

7. Cell according to Claim 6, wherein the first subcell (301) and the third subcell (303) each have a thermal mass, the thermal masses of the first and third subcells differ from each other by not more than 5%, preferably 1%, of the lesser of the two thermal masses; and the second subcell (302) has a thermal mass which differs by not more than 5%, preferably 1%, from twice the thermal mass of the third subcell (303).

8. Cell according to Claim 6 or 7, wherein the first insulating body (304) and the second insulating body (306) have the same structural form.

9. Cell according to any of the preceding claims, wherein: the first subcell (101; 301) and the second subcell (102; 302) each comprise: a first electrode, a second electrode, having a higher electrical potential than the first electrode, and a separator arranged between the two electrodes; the first insulating body (103; 304) is surrounded on all sides, with the exception of one or more electrical terminals (113, 114; 313) connected to the first heating structure (107, 108; 207), by an electrolyte-stable foil (120; 220); the electrolyte-stable foil (120; 220) electrically insulates at the same time the first insulating body (103; 304) from the first subcell (101; 301) and from the second subcell (102; 302); and the first subcell (101; 301), the second subcell (102; 302), and the part of the first insulating body (103; 304) that is arranged in the interspace between the first and second subcells and is surrounded by the electrolyte-stable foil (120; 220) are immersed in a liquid electrolyte.

10. Cell according to any of Claims 1 to 8, wherein the first subcell (101; 301) and the second subcell (102; 302) each comprise: a first electrode, a second electrode, which has a higher electrical potential than the first electrode, and a solid-state electrolyte which is arranged between the two electrodes.

11. Cell according to any of the preceding claims, wherein the first thermally insulating material or the second thermally insulating material is of low flammability according to DIN 4102-1.

12. Cell according to any of the preceding claims, wherein the first thermally insulating material has a thermal conductivity which is less than 0.3 W / (m·K), or the second thermally insulating material has a thermal conductivity which is less than 0.3 W / (m·K).

13. Battery comprising a cell (100; 300) according to any of the preceding claims.

14. Vehicle comprising a battery according to Claim 13.