WO2020156644A1

WO2020156644A1 - Modular battery system with parallel cell cooling

Info

Publication number: WO2020156644A1
Application number: PCT/EP2019/052126
Authority: WO
Inventors: Stefan Andreas MEYER; Robert Jakobsson
Original assignee: Skopos Limited
Priority date: 2019-01-29
Filing date: 2019-01-29
Publication date: 2020-08-06

Abstract

The present invention relates to a modular, full enclosed, liquid cooled battery system including a plurality of battery cells and a plurality of cell frames. The cell frames are connected to each other in a serial manner, thereby forming a battery housing containing the battery cells and a coolant flow is allowed through the battery housing. Each cell frame is shaped as a one-sided open box, such that a plurality of hollow spaces is formed within the battery housing. Each cell frame has at least two liquid feedthrough openings, such that when a coolant flow is established through the battery housing, the coolant flows through the hollow spaces including the battery cells in a parallel manner.

Description

MODULAR BATTERY SYSTEM WITH PARALLEL CELL COOLING

[1] The present invention relates to a battery system allowing for efficient and homogeneous cooling of its battery cells.

[2] In view of the prospective limited availability of classical fuels and the increasing level of air pollution due to engine exhaust gases, focus has been laid on alternative drive solutions in recent years. Irrespective of the primary energy source, most approaches require a battery system with a high power density, a long lifetime and high charging performance.

[3] Building a battery system is the mechanical, electrical and thermal integration of a large number of battery cells into a working unit. Further aspects to consider are chemical compatibility of the used components, safety features in case of a thermal runaway and ease of mass production.

[4] Adequate temperature control of each battery cell within a battery system is a key requirement, in particular, when charging or discharging the battery. Failure to adhere to temperature limits of, for instance, lithium-ion battery cells may lead to gradual deterioration of the battery performance or even to a rapid and dangerous destruction of the battery.

[5] Conventionally, controlling the temperature of battery cells in a battery system may be performed indirectly, for instance, by providing cooling plates at the sides of a battery module or by providing thin metal pipes snaking their way along the battery cells in order to dissipate heat generated by the battery cells by conduction. Alternatively, an active cooling of the battery cells may be provided by circulating a coolant liquid through the battery system.

[6] However, when controlling the temperature of battery cells in these ways, efficiency of the heat dissipation is poor and homogeneous cooling of the battery cells cannot be accomplished, which results in a reduced battery lifetime, limited battery charging performance and even an increase of danger.

[7] In view of the foregoing, it would be desirable to provide a new battery system allowing for efficient, homogeneous cooling of the battery cells.

[8] This is achieved by the features of the independent claims.

[9] The present invention relates to a battery system. The battery system comprises a plurality of battery cells and a plurality of battery cell frames. The plurality of cell frames are connected to each other in a serial manner, thereby, forming a battery housing in which the plurality of battery cells is contained. Further, a coolant is allowed to flow through the battery housing. Each one of the cell frames is shaped as a one-sided open box formed by a base section and a plurality of side sections enclosing the interior of each cell frame, such that a plurality of separated hollow spaces is formed within the battery housing with the coolant flowing through said hollow spaces. The hollow spaces of the battery housing are separated from each other by the base sections of the plurality of cell fames. Each of the cell frames has at least two liquid feedthrough openings for establishing the coolant flow through the hollow spaces in a parallel manner.

[10] In other words, the battery system comprises a battery housing with a plurality of hollow spaces, wherein the hollow spaces of the battery housing are sequential chambers holding the battery cells. The particular setup of the battery housing is obtained by connecting a plurality of one-sided open box-shaped cell frames in a serial manner by connecting the cell frames to one another. A hollow space of the battery housing is formed within each of the plurality of cell frames. Each one of the hollow spaces contains battery cells. The hollow spaces are in fluid connection to each other by at least two liquid feedthrough openings provided on one side (base section) of each cell frame, wherein the side of the cell frame providing the liquid feedthrough openings is the side of each cell frame separating the hollow spaces of the battery housing. The liquid feedthrough openings allow to establish a coolant flow through the hollow spaces containing the battery cells in a parallel manner.

[1 1 ] That is, the coolant enters the battery system and unimpededly flows into each one of the cell frames through one of the at least two liquid feedthrough openings of each cell frame. Subsequently, the coolant flow is split up and flows through the hollow spaces holding the battery cells. In other words, the coolant flow entering the battery housing is separated into a plurality of coolant flow portions, wherein each coolant flow portion flows through one of the hollow spaces. Once having passed the hollow spaces, the coolant flow portions reunite. That is, coolant flows through the cell frames and, thereby, the hollow spaces, in a parallel manner. Subsequently, the coolant may unimpededly flow through another one of the at least two liquid feedthrough openings of each cell frame and may exit the battery housing.

[12] It is a particular advantage of above-described battery system that battery cells within the battery housing are cooled in equal measure as the coolant is prevented from being heated up excessively by the heat acquired from battery cells located further upstream. That is, allowing for a coolant flow in a parallel manner through the insides of the cell frames ensures a substantially improved temperature homogeneity throughout the battery system. [13] According to another aspect, the at least two liquid feedthrough openings of each cell frames are located at opposing positions on the base section of respective cell frame. Thereby, fluid connections between adjacent hollow spaces of the battery housing are formed.

[14] In other words, the feedthrough openings are located on the base section of each cell frame which is located in between the hollow spaces of the battery housing. In particular, the positions of the at least two openings are substantially opposing each other with respect to a main axis of the battery system through a center point the plurality of base sections of the plurality of cell frames connected to each other in a serial manner. Due to the opposing eccentric positions of the openings and, thereby, the rather large distance between the at least two liquid feedthrough openings of each cell frame, the coolant is led through the hollow spaces in a parallel manner.

[15] According to another aspect, the battery cells are provided within the hollow spaces of the battery housing at positions different from the positions of the at least two liquid feedthrough openings. Thereby, at least two coolant flow channels are formed.

[16] That is, the battery cells are located within the cell frames such that a flow of coolant flows through each of the cell frames and respective liquid feedthrough openings unimpededly and without hindrance. In other words, at least two coolant flow channels are formed by the above- described positioning of the battery cells within the cell frames and the positions of the at least two liquid feedthrough openings of each cell frame.

[17] In the case where the liquid feedthrough openings are located opposing each other, the coolant flow channels are opposing each other as well, such that a coolant flow channel is located at one side of the hollow spaces and another coolant flow channel is located at an opposing side of the hollow spaces with the battery cells being located in between said coolant flow channels. Accordingly, a coolant flow through all hollow spaces is established in a parallel manner.

[18] That is, the coolant unimpededly flows into each cell frame via one of the coolant flow channels and splits into a plurality of partial coolant flows. Subsequently, each partial coolant flow flows through one of the plurality of hollow spaces holding the battery cells. The partial coolant flows reunite within another coolant flow channel opposing the one coolant flow channel and may exit the battery system.

[19] According to another aspect, one of the at least two coolant flow channels is closed at a first end side of the battery housing, and another one of the coolant flow channels is closed at a second end side of the battery housing. [20] With this approach, a coolant flow through the battery housing is formed by pumping coolant into an open end of a first coolant flow channel. The coolant flows unimpededly through said first flow channel and, subsequently, through the plurality of hollow spaces holding the plurality of battery cells in a parallel manner into an opposing coolant flow channel, from which the coolant exits the battery housing unimpededly.

[21 ] The parallel flow through the plurality of hollow spaces is achieved by all possible coolant paths through the battery housing exhibiting an equal flow resistance. For instance, the flow resistance of a first coolant path through a first section of the first coolant channel, the first hollow space and a first section of the second coolant channel is equal to the flow resistance of a second coolant path through a second section of the first coolant channel, the second hollow space and a second section of the second coolant channel. Further, a pressure difference between the second coolant channel and the first coolant channel is equal for each one of the plurality of hollow spaces.

[22] According to another aspect, the base section of each cell frame provides a plurality of cell openings. The base section being the side of the cell frames in between the hollow spaces of the battery housing. Each of said cell-openings is configured to mechanically arrest one battery cell out of the plurality of battery cells.

[23] In other words, the cell frames provide fixing structures (cell openings), wherein the battery cells are held. This allows to hold the battery cells at fixed positions within the hollow spaces inside the cell frames. Further, the cell openings provide electrical feedthrough through the base section of the cell frames for a pole of the battery cells held by the cell openings.

[24] According to another aspect, the battery system further comprises a plurality of spring- sheets. Each spring sheet is positioned between the base section of one of the plurality of cell frames and the battery cells within the hollow space of the cell frame adjacent to the one of the plurality of cell frames. Each spring sheet comprises a plurality of spring arms and provides electrical connection between the battery cells positioned within one cell frame in a parallel manner and between the battery cells within adjacent cell frames in a serial manner.

[25] In other words, multiple spring sheets are provided to electrically connect the equal poles of the battery cells within a cell frame in a parallel manner. Further, said spring sheets electrically connect the plus and minus poles of the battery cells within adjacent cell frames. That is, the battery cells within a cell frames are connected to each other in parallel, and the battery cells within cell frames next to each other are connected in series. A spring sheet may be of substantially flat shape with a plurality of spring arms for establishing electrical connection among the battery cells of adjacent cell frames.

[26] According to another aspect, each spring sheet provides a layered structure including an inner copper layer enclosed by two outer steel layers.

[27] In other words, when viewed in cross section along a thickness direction of the spring sheet, a first outer layer of steel is followed by an inner layer of copper, which is followed by a second outer layer of steel. It is a particular advantage of such a layered structure of the spring sheet that the spring sheet exhibits the excellent conductivity of copper as well as the easier welding properties of steel.

[28] Each spring sheet may further comprise additional Zinc or Nickel outer layers enclosing the two outer steel layers. In other words, when viewed in cross section along a thickness direction of the spring sheet, a first outer layer of Zinc or Nickel is followed by a first outer layer of steel, which is followed by an inner layer of copper, which is followed by a second outer layer of steel, which is followed by a second outer layer of Zinc or Nickel.

[29] The outer Zink or Nickel layers provide a protective coating of the outer steel layers.

[30] According to another aspect, each spring arm is located at a position on the spring sheet corresponding to a position of one of the battery cells within the cell frames.

[31 ] According to another aspect, each spring sheet can be welded to either one of plus and minus poles of the battery cells within a cell frame. In particular, each spring sheet may be laser- welded to either one of plus and minus poles of the battery cells.

[32] That is, one of the plus and minus poles can be welded to the spring sheet, and electrical connection to respective battery cells is established via the welded joint. According to the above, the spring sheet establishes electrical connection to the battery cells of an adjacent cell frame by the mechanical force provided by the spring arms of the spring sheet. It is a particular advantage of this setup that electrical connection of the battery cells is achieved by a single connecting portion (the spring sheet), instead of a connecting portion provided for each one of the battery cells.

[33] According to another aspect, each spring sheet may be laser-welded to either one of plus and minus poles of the battery cells applying a laser-welding technique.

[34] According to another aspect, the battery system further comprises a first lid closing the battery housing on a first end side and a second lid closing the battery housing on a second end side. The first lid, the plurality of cell frames and the second lid are connected to each other in a serial manner.

[35] In other words, the battery housing, which is formed by the plurality of cell frames connected to each other in a serial manner, is terminated on both end sides by a lid. That is, the first and second lids form the end parts of the battery system, thereby covering the end sides of the battery housing.

[36] According to another aspect, the first lid provides a first opening and the second lid provides a second opening, wherein the first and second openings are provided at positions of the first and second lids according to the positions of the at least two liquid feedthrough openings on the base sections of the plurality of cell frames. Thereby, fluid connections according to the at least two liquid feedthrough openings of the plurality of cell frames are formed.

[37] In other words, the first and the second lid each have an opening at a position corresponding to a position of a liquid feedthrough connecting the hollow spaces of the battery housing, wherein the positions of the openings of the first and the second lid correspond to positions of different liquid feedthroughs.

[38] That is, the first lid provides the first opening at a position different from the center position of the first lid. Further, the second lid provides the second opening at a position different from the center position of the second lid and different from the position of the first opening of the first lid. In particular, when viewed along a length direction of the battery system, which is the direction along which the plurality of cell frames are connected to each other, the position of the first opening of the first lid and the position of the second opening of the second lid do not coincide. Furthermore, the first and second openings may be provided at substantially opposing positions with respect to a center axis through the battery system along a length direction. In particular, the first and second openings of the first and second lid are located at positions according to the positions of the at least two coolant flow channels.

[39] According to another aspect, the first and the second lid provides an electrical feedthrough opening. Further, the battery system comprises a first current-collector providing an electric connection through the electrical feedthrough opening of the first lid. Still further, the battery system comprises a second current-collector providing an electric connection through the electrical feedthrough opening of the second lid. [40] In other words, an electric connection to the battery cells within the first and the last cell frames in the series of the plurality of cell frames is established by a current-collector and electric feedthrough openings of the two lids. The current-collectors may be, for instance, sheets made of electrically conducting material with feedthrough portions providing connection to the first and the last spring sheet of the battery system. With this setup, the battery system can be easily connected to, for instance, a charging apparatus, a load, or the like. That is, the electric feedthroughs allow for easy implementation of the battery system in any electrical system.

[41 ] According to another aspect, the first and second current-collectors comprise a layered structure including an inner copper layer enclosed by two outer steel layers.

[42] In other words, the current-collectors exhibit layers similar to the ones described above for the spring sheets. That is, the layered structure of the current-collectors combines the superior conductivity of copper with the better welding properties of steel.

[43] The current-collectors may further comprise protective Zinc or Nickel layers enclosing the two outer steel layers. The present invention is not limited to Zinc or Nickel and every other material suitable for providing a protective layer may be used.

[44] However, in its simplest implementation the current-collectors may only be implemented by a single layer made of copper or bronze.

[45] According to another aspect, the battery system further comprises a current collector frame provided between a first cell frame out of the plurality of cell frames and the first lid or between a last cell frame out of the plurality of cell frames and the second lid. The current collector frame serves as an adapter for the first or second lid in a case where the first and second lid are constructed equally.

[46] In other words, when using a current collector frame as an adapter between one of the two lids and a cell frame, the first and second lids can be manufactured equally.

[47] According to another aspect, the battery system further comprises a battery management system and a plurality of printed circuit boards. The plurality of printed circuit boards are configured to provide electric potential signals to the battery management system, wherein each one of the printed circuit boards is provided within one of the plurality of cell frames. Each printed circuit board comprises a measurement pad, which is electrically connected to the plus or the minus poles of the battery cells within one of the plurality of cell frames, and a plurality of signal pads or a first connector as well as a cell board connector. The cell board connector is configured to establish contact to the plurality of signal pads or the first connector of another printed circuit board. The printed circuit boards are connected to each other and to the battery management system in a serial manner via the signal pads or the first conenctors and the cell board connectors. Thereby, each electric potential signal is provided to the battery management system.

[48] In other words, each of the cell frames contains a printed circuit board. Further, the plurality of circuit boards are serially connected to each other and to the battery management system. Each printed circuit board provides a measurement pad for electrical connection to the plus or minus poles of the battery cells within the cell frame. Further, each printed circuit board includes a plurality of signal pads or a first connector and a cell board connector for connecting to the printed circuit boards of adjacent cell frames by contacting the signal pads or the first connector of an adjacent printed circuit board. In particular, a connection of two printed circuit boards is established by the portion of the printed circuit board holding the signal pads or the first connector being inserted to the cell board connector of the other printed circuit board. In this way, a plurality of circuit boards may be connected to each other in series. The electric potential signal is thereby passed to the printed circuit board of the adjacent cell frame. Further, each printed circuit board is configured to pass an electric potential signal of an adjacent printed circuit board to the other adjacent printed circuit board. That is, electric potential signals of all cell frames are passed from printed circuit board to printed circuit board and, finally, to the battery management system, which may also comprise a cell board connector for connecting to one of the plurality of printed circuit boards.

[49] The first connector may be a male connector to be inserted into a cell board connector of an adjacent printed circuit board. In this case, the cell board connector is a female connector. The first connector may be a female connector to be connected to a cell board connector of an adjacent printed circuit board. In this case, the cell board connector is a male connector.

[50] According to another aspect, the battery system further comprises a plurality of temperature sensors, which are provided within the plurality of cell frames. Each of the temperature sensors are configured to detect a temperature of the battery cells within one of the plurality of cell frames. Further, each of the temperature sensors is connected to the printed circuit board within the cell frame, which is configured to pass the temperature signal corresponding to the detected temperature to the battery management system via the signal pads or the first connector.

[51 ] That is, in addition to measurement values of electrical potential, temperature measurement values are passed from printed circuit board to printed circuit board and, finally, to the battery management system. With this approach, electric potential values and temperature values corresponding to each one of the cell frames are provided to the battery management system and can thus be used for monitoring the temperature within the battery system.

[52] According to another aspect, a coolant flow through the battery system is established by pumping a coolant into one of the at least two coolant flow channels.

[53] In this way, the coolant flows into the inlet coolant flow channel and through the plurality of hollow spaces holding the battery cells in a parallel manner to the outlet coolant flow channel. It is a particular advantage of the coolant flowing through the hollow spaces in parallel that the temperature homogeneity across the battery cell is increased and that the total cooling capability is higher.

[54] The coolant flow may be established by connecting the battery system of the present invention to a coolant pumping system configured to pump a coolant into the coolant inlet of the battery system, such that the coolant enters one of the coolant flow channels, flows through the plurality of hollow spaces holding the battery cells in a parallel manner, enters another coolant flow channel and exits the battery housing via the coolant outlet.

[55] According to another aspect, a coolant flow through the battery system is established by pumping cooling liquid into one of the first opening of the first lid and the second opening of the second lid.

[56] In other words, the coolant enters a coolant flow channel via the first opening of the first lid, flows through the hollow spaces of the battery housing in a parallel manner end exits the battery housing via another coolant flow channel and the second opening of the second lid.

[57] According to another aspect, each cell frame is made of fiberglass reinforced plastic.

[58] A fiberglass reinforced plastic cell frame provides a rigid structure for the integration of the battery cells.

[59] According to another aspect, each cell frame comprises a sealing groove including a seal, which seals the connection of adjacent cell frames.

[60] In other words, the coolant within the battery housing is prevented from exiting the battery housing at a position where the cell frames are connected to each other by providing a seal in a sealing groove of the cell frames. [61 ] According to another aspect, the battery system further comprises a frame attached to and enclosing the battery housing, thereby increasing the mechanical stability of the battery system.

[62] That is, in order to reinforce the mechanical integrity of the battery system, a frame is attached to the battery housing, thereby assisting to carry any forces associated to the weight and possible acceleration of the cells.

[63] The battery system of the present invention provides improved temperature control capabilities. In particular, homogeneous cooling of the battery cells within the hollow spaces of the battery is achieved by allowing a flow of coolant to flow through the hollow spaces in a parallel manner.

[64] Additional benefits and advantages of the invention will become apparent from the detailed description of an embodiment and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[65] Fig. 1A is a cross-sectional illustration of the basic concept of a battery system according to the present invention.

[66] Fig. 1 B is a schematic illustration of the basic concept of the battery system according to the present invention.

[67] Fig. 2 is an illustration of an outer appearance of a battery system according to the present invention.

[68] Fig. 3A is an illustration of a cell frame according to the present invention as seen from diagonally above.

[69] Fig. 3B is an illustration of a cell frame according to the present invention as seen from diagonally below.

[70] Fig. 4 is an illustration of a simplified spring sheet according to the present invention.

[71 ] Figs. 5A to 5D are illustrations of examples of spring arms of a spring sheet according to the present invention.

[72] Figs. 6A to 6C are illustrations of the assembly of a plurality of battery cells, a cell frame, a spring sheet and a printed circuit board according to the present invention. [73] Fig. 7 is an illustration of the connection of cell frames, each holding battery cells, a spring sheet and a printed circuit board.

[74] Fig. 8A is an illustration of a lid according to the present invention as seen from the outside of the battery system.

[75] Fig. 8B is an illustration of a lid according to the present invention as seen from the inside of the battery system.

[76] Fig. 9A is an illustration of a current-collector frame according to the present invention as seen from the top.

[77] Fig. 9B is an illustration of a current-collector frame according to the present invention as seen from the bottom.

[78] Figs. 10A to 10C are illustrations of a current collector and its connection to a current collector pole

[79] Figs. 11 A and 1 1 B are illustrations of the assembly of the positive end side of the battery system 1.

[80] Figs. 12A and 12B are illustrations of the assembly of the negative end side of the battery system 1.

[81 ] Fig. 13 is an illustration of the layered structure of a spring sheet and/or a current collector according to the present invention.

[82] Figs. 14A and 14B are illustrations of printed circuit boards according to the present invention.

[83] Fig. 15 is a schematic illustration of the connections of the printed circuit boards and the battery management system.

[84] Fig. 16 is an illustration of the supervision electronics.

DESCRIPTION OF PREFERRED EMBODIMENT

[85] In the following, a preferred embodiment will be described in detail through reference to the drawings. [86] Fig. 1 a shows a cross-sectional illustration of the basic concept of a battery system 1 according to the present embodiment. Fig. 1 b shows a schematic illustration of the concept of the battery system 1 according to the present embodiment. A detailed illustration and description of the components of the battery system 1 will be given further below.

[87] The battery system 1 comprises a plurality of battery cells 10. For reasons of clarity, only a single battery cell is marked with a reference numeral in Fig. 1 a. Further, the battery system 1 illustrated in Fig. 1 a comprises cell frames 20a-20e connected to each other in a serial manner to form the battery housing of the battery system 1. The battery system 1 is concluded on a first end side by a first lid 50 and on a second end side by a second lid 60.

[88] Although the battery system 1 illustrated in Fig. 1 a comprises five cell frames 20a-20e, the present invention is not limited to this. Preferably, the battery system comprises two or more cell frames, more preferable five to fifty cell frames, even more preferably eight to twenty-five cell frames.

[89] The first lid 50 provides a first opening 51 and the second lid (60) provides a second opening 61. The battery housing includes a hollow space within each one of the cell frames 20a- 20e. The hollow spaces of the battery housing are separated from each other except for two liquid feedthrough openings 21 , 22 provided at opposing positions of each one of the cell frames 20a- 20e. For reasons of clarity, only the liquid feedthrough openings of a single cell frame are marked with reference numerals in Fig. 1 b. The plurality of battery cells 10 are located within the hollow spaces of the battery housing.

[90] At the positions of the opposing liquid feedthrough openings, two coolant flow channels 31 , 32 are formed through which a coolant may flow without significant hindrance.

[91 ] A flow of a coolant through the battery system 1 is illustrated as bold arrows. As illustrated in Fig. 1 A and 1 B, the coolant enters the battery system 1 via the first opening 51 of the first lid 50 and flows through the first coolant flow channel 31. Subsequently, the coolant flows through the hollow spaces holding the plurality of battery cells 10 in a parallel manner and enters the second coolant flow channel 32, which leads the coolant to the outside of the battery system 1 through the second opening 61 of the second lid 60.

[92] The parallel coolant flow through the hollow spaces holding the plurality of battery cells 10 is achieved by the coolant flow channels 31 , 32, which provide a negligible flow resistance to the coolant flow with respect to the flow resistance through the hollow spaces holding the plurality of battery cells. This is achieved by the dense arrangement of the battery cells within the cell frames 20a-20e with respect to the coolant flow channels 31 , 32 providing negligible hindrance to the coolant flow.

[93] Although the battery system 1 illustrated in Figs. 1 a and 1 b comprises five cell frames 20a- 20e, the present invention is not limited to this. A battery system 1 according to the present invention may comprise any number of cell frames 20a-20e. Preferable, a battery system 1 according to the present invention comprises two or more cell frames, more preferably five to 50 cell frames and even more preferable eight to twenty-five cell frames. Further, although according to the illustration of Figs. 1 a and 1 b, two coolant flow channels 31 , 32 are provided, the battery system 1 may comprise a different number of coolant flow channels 31 , 32, provided that each one of the coolant flow channels is associated with either the coolant entering or exiting the battery system 1. Preferably, two or more channels are provided, more preferable four to 10, even more preferably six to eight.

[94] Fig. 2 shows an illustration of an outer appearance of the battery system 1 according to the present embodiment. The battery system 1 further comprises a frame 130 surrounding the battery housing, which will be described later.

[95] In the following, first, a detailed description of all components of the battery system 1 will be given. Then, the assembly of the battery system 1 will be illustrated and described.

[96] Figs. 3a and 3b show illustrations of one of the cell frames according to the present invention as seen from diagonally above and below, respectively. The cell frame 20 is shaped as a one-sided open box and comprises three liquid feedthrough openings 21 and another three liquid feedthrough openings 22 on a base section 23 of the cell frame 20. As indicated above, the present invention is not limited to a total of six coolant flow channels. Accordingly, the present invention is not limited to a total of six liquid feedthrough openings 21 , 22. Preferably, two or more liquid feedthrough openings are provided, more preferable four to ten and even more preferably six to eight liquid feedthrough openings are provided.

[97] Further, the cell frame comprises a plurality of cell openings 24 provided on the inside of the base section 23 of the cell frame 20 as well as a plurality of fixing clips 25 and a plurality of fixing clip grooves 26. Still further, the cell frame 20 comprises a sealing groove 27 and a plurality of tie rod openings 28 as well as fixtures 29 for a printed circuit board 1 10, which will be described in detail below. [98] The cell frame 20 according to the present embodiment is made of fiberglass reinforced plastic providing a rigid structure for the mechanical integration of the battery cells 10. Due to the shape of a one-sided open box, a plurality of separated hollow spaces is formed when a plurality of cell frames 20 according to the present embodiment are stacked in a parallel manner.

[99] The liquid feedthrough openings 21 , 22 are provided at positions in an edge area of the base section 23 of the cell frame 20. In particular, the three liquid feedthrough openings 21 are located at positions opposing the other liquid feedthrough openings 22. The coolant flow channels 31 , 32 are important to guide the flow of the coolant inside the battery used for thermal control of the battery cells 10.

[100] A plurality of cell openings 24 is provided on the inside of the base section 23 and are realized as openings of the base section shaped according to the shape of the battery cells 10 to be positioned within the cell frame 20. That is, each one of the plurality of battery cells 10 is held by a cell opening 24 of a cell frame 20. In other words, the cell openings 24 allow for mechanically arresting battery cells 10 in the cell frame 20 by inserting them into the hole with their plus side, for example.

[101] The cell frame 20 further provides a plurality of cell alignment taps on the outer side of the base sections 23 of the cell frame 20, which are important for holding battery cells 10 in place that are placed on top when assembling the battery system 1.

[102] The cell frame 20 further comprises a plurality of fixing clips 25 and a plurality of fixing clip grooves 26. When two cell frames 20 are connected to each other, the fixing clips 25 of one cell frames 20 are arrested in the fixing clip grooves 26 of the other cell frame 20 such that a mechanical connection is formed between the two cell frames 20. That is, the fixing clips 25 on one side and corresponding fixing grooves 26 on the other side allow for easy assembly of the cell frames 20.

[103] The cell frame 20 comprises a sealing groove 27, which makes space for a sealing ring that is either a separated part or permanently connected to the cell frame 20 using, for example, 2K injection molding technology. The sealing ring establishes a liquid-proof connection to the next cell frame 20 or to the current collector frame or to a battery lid placed on top. The battery lid and current collector frame are described later.

[104] Further, a plurality of tie rod openings 28 is provided within the outer sides (side sections) of the cell frame 20. In an assembled battery system 1 , stabilizing rods are provided through said tie rod openings 28 of the plurality of cell frames 20a-20e. That is, the tie rod openings 28 allow for insertion of a metal tie rod, which is able to build up sufficient pressure on the seals to make the system liquid-proof.

[105] Fig. 4 is an illustration of a spring sheet 40 according to the present invention. The spring sheet 40 is a metal sheet with a thickness of about 0.2 mm to 0.6 mm. The spring sheet 40 contains dimples 43 that allow it to be welded to the plus pole of each battery cell 10. The spring sheet is shaped such that it may be positioned on the base section 23 of a cell frame 20. That is, it provides a plurality of openings at positions corresponding to the positions of the cell alignment taps. Further, the spring sheet comprises a spring sheet tongue 42 for connecting the spring sheet to a printed circuit board, which is described later.

[106] The spring sheet 40 comprises a plurality of spring arms 41 , which allow for electrical connection of the battery cells 10 within a cell frame and the battery cells 10 within an adjacent cell frame. The spring arms 41 are located at positions corresponding to the positions of the battery cells 10 within a cell frame 20. Examples of the spring arms 41 within the area indicated by the dashed line are illustrated in Figs. 5A to 5D.

[107] Figs. 5A to 5D are illustrations of examples of spring arms of a spring sheet according to the present invention.

[108] The spring arms 41 of the spring sheet 40 provide elastic members sticking out of the plane of the spring sheet 40. Examples of the elastic members illustrated in Figs. 5A to 5D. Even though the designs of spring arms are quite different, the idea is always the same: on one side, the spring sheet is welded to battery cells 10 within a cell frame. On the other side, the spring arms 41 establish a connection between the battery cells 10 in the next cell frame 20.

[109] The purpose of the spring sheet tongue 42 is to establish a connection between the potential of the plus or minus poles of the battery cells 10 with the printed circuit board, which is described below. This allows for an easy connection to the battery management system.

[1 10] Figs. 6A to 6C are illustrations of the assembly of a plurality of battery cells 10, a cell frame 20, a spring sheet 40 and a printed circuit board 1 10. Figs. 6A and 6B show an overview of the assembly of said features. Fig. 6C is a detailed illustration of the portion indicated by the dashed lines in Fig. 6A and shows the electrical connection of the battery cells 10, the spring sheet 40 and the printed circuit board 1 10. [1 1 1] As illustrated in Fig. 6A, a spring sheet 40 is positioned on the outer side of the base section 23 of the cell frame 20. As illustrated in Fig. 6B, a plurality of battery cells 10 is located within the cell frame 20. The positions of the battery cells 10 do not coincide with the positions of the liquid feedthrough openings 21 , 22 of the cell frame 20. Thereby, coolant flow channels 31 , 32 through the hollow within the cell frame 20 holding the battery cells 10 are formed.

[1 12] Fig. 6C is a detailed illustration of the connection of the battery cells 10 and the spring sheet 40 as well as the connection of the spring sheet 40 and the printed circuit board 1 10. The positive side of each battery cell 10 is welded to the spring sheet 40 along the hole in the dimple 43. The spring sheet 40 is electrically connected to the printed circuit board 1 10 via the spring sheet tongue 42. However, it is to be emphasized that the dimple 43 does not necessarily have to have a hole. The hole mainly serves to make it easier to weld along a predefined line, but may also be omitted for welding through the material.

[1 13] Fig. 7 is an illustration of the connection of cell frames 20a-20d, each holding battery cells 10, a spring sheet 40 and a printed circuit board 1 10. The cell frames 20a-20d are connected to each other in a serial manner and fixed by the fixing clips 25 and the fixing clip grooves 26. The liquid proof connection between the cell frames 20a-20d is established by the seals positioned within the sealing groove 27 of each cell frame 20a-20d. The electrical connection between the battery cells 10 of adjacent cell frames 20 is established by the spring sheets 40 being positioned between each of the cell frames 20, wherein the battery cells 10 are welded to the spring sheets 40 on one side. On the other side, electrical connection is established by the mechanical force of the spring arms 41 of the spring sheets 40.

[1 14] Fig. 8A is an illustration of a lid 50, 60 as seen from the outside of the battery system 1. Fig. 8B is an illustration of a lid 50, 60 as seen from the inside of the battery system 1.

[1 15] The lid 50, 60 provides an opening 51 , 61 for coolant inlet/outlet, an electrical feedthrough opening 52, 62, a plurality of tie rod openings 28, a plurality of fixing clips 25, a pocket 53, 63 for holding a battery management system, which is described below, and a CAN opening 54, 64 for providing a feedthrough opening for connecting the battery management system to external control electronics, for instance, via a CAN bus of a vehicle.

[1 16] The battery lid 50, 60 is a part that contains three openings. The openings 51 , 61 are designed to be the coolant inlet or outlet. The electric feedthrough opening 52, 62 is for the plus or minus pole of the battery. To ensure that no liquid can escape from the inside, the pole is sealed by a sealing ring placed on a pole sealing groove. The CAN opening 54, 64 provides a feedthrough opening for connecting a CAN port of the battery management system to external control electronics. The lid 50, 60 provides a pocket 53, 63, which is a space for holding the battery management system, which supervises cell voltages and cell temperatures inside the battery system 1. Just like the cell frame 20, the lid 50, 60 has a plurality of fixing clips 25 that allow an easy assembly and a plurality of tie rod openings 28 that allow insertion of a metal tie rod for building up sufficient pressure on the seals.

[1 17] The lids (first and second lid 50, 60) are provided in the battery system 1 to close the battery on both end sides, and to provide feedthrough openings for coolant flow, electrical connection, and control electronics.

[1 18] Fig. 9A is an illustration of a current-collector frame 90 according to the present invention as seen from the top. Fig. 9B is an illustration of a current-collector frame 90 according to the present invention as seen from the bottom.

[1 19] The current-collector frame 90 is a plastic part that contains features corresponding to the features of a cell frame 20. In the following, only different features are described. The current- collector frame 90 is slimmer than the cell frame 20 and is designed to be an adaptive piece between a battery lid 50, 60 and a cell frame 20. It is the purpose of the current collector frame 90 to hold the current collector 70. The current collector frame 90 may further be configured to hold a small printed circuit board 140 which will be described below..

[120] Using such current-collector frame 90 between either the first lid 50 and the first cell frame 20a or the second lid 60 and the last cell frame 20e allows for the first and second lids 50, 60 to be structurally equal, as illustrated, for example, in Fig. 1A.

[121] The current-collector frame 90 provides three liquid feedthrough openings 21 and another three liquid feedthrough openings 22 corresponding to the liquid feedthrough openings 21 , 22 of a cell frame 20. Further, the current-collector frame 90 provides tie rod openings 28, fixing clips, ceiling grooves 91 a, and cell alignment taps.

[122] Figs. 10A to 10C are illustrations of a current collector 70 and its connection to a current collector pole 73. The current collector 70 is a metal sheet with a thickness of about 2 mm to 4 mm. It has a single pole alignment tab hole 72 in its center that allows placing and welding the plus/minus pole 73 to the sheet. Further, the current collector 70 provides cell alignment holes 71 , which allow the sheet to fit on top of a cell frame 20. [123] The pole 73 is a cylindrical metal part. On one side it has the pole alignment 74 that fits into the pole alignment tab hole 72 of the current collector 70. On the other side, it has a threaded connection hole 75 that allows to easily attach a high current cable or a copper bar with a screw to the pole 73.

[124] In order to complete the assembly of the stacked cell frames including the battery cells 10, the spring sheet 40 and the printed circuit board 1 10, both ends of the battery system one are terminated by plastic lids 50, 60.

[125] Figs. 1 1A and 1 1 B are illustrations of the assembly of the positive side of the battery system 1. The first cell frame 20a is connected to the first lid 50 with the first current collector 70 being positioned in between. The first lid 50 and the first cell frame 20a are connected to each other via the fixing clips 25 of the first lid 50 and the fixing grooves 26 of the first cell frame 20a. The current of the parallel battery cells 10 is collected by the first current collector 70, which has the threaded pole 73 welded to it that fits through the corresponding electrical feedthrough opening 52 of the first lid 50.

[126] Figs. 12A and 12B are illustrations of the assembly of the negative side of the battery system 1. Terminating the negative end of the battery system 1 is similar but not identical to the positive end. The current collector frame 90 is a thin plastic piece that holds the second current collector 80 on one side and the spring sheet 40 on the other. Where these two metal parts touch, a sound electrical connection may be established by welding them together. With this new part 40, 80, 90 and the second lid 60, the negative side of the battery system 1 can be closed as illustrated. The second lid 60, the current collector frame 90 holding the second current collector 80 and a spring sheet 40 and the last cell frame 20e are connected to each other by the fixing clips 25 of the second lid 60 and the cell frame 20e and the fixing clip grooves 26 of the current collector frame 90.

[127] Although in the present embodiment, the negative side of the battery system 1 is terminated by using a current collector frame 90 as an adapter between the second lid 60 and the last cell frame 20e, a current collector frame 90 may be used at the positive side of the battery system alternatively or additionally.

[128] The use of the current collector frame 90 allows the first and second lids 50, 60 to be constructed equally and makes space for the current collector 80 in the battery system 1 on the negative side. [129] Fig. 13 is an illustration of the layered structure of a spring sheet 40 and/or a current collector according to the present invention. The spring sheet, which is a metal sheet, is preferably made of a layered material with the composition of copper and stainless steel. That is, a layer 42 of copper is enclosed by two outer layers 41 , 43 made of stainless steel. This structure combines the excellent conductivity of copper with the better welding parameters of steel. Just as the spring sheet 40, the current collector 70, 80 may provide the described structure of a copper layer enclosed by two steel layers. Additionally, the spring sheet 40 and/or a current collector may provide protective outer layers, for example, of Zinc or Nickel.

[130] Although in the present embodiment, the spring sheet 40 and/or the current collector 70, 80 may be made of 60 % copper and 40 % stainless steel, the present invention is not limited to this and the copper/steel ratio may be any value as long as an inner copper layer is enclosed by two outer steel layers.

[131] Fig. 14A is an illustration of a printed circuit board 1 10 according to the present invention. The printed circuit board 1 10, PCB, is a single- or multilayered printed circuit board with a measurement pad 1 1 1 , a plurality of signal pads 1 12 and a PCB board connector 1 13. A printed circuit board 1 10 is integrated into each cell frame 20a-20e and can measure the cell voltage with its measurement pad 1 1 1 . This voltage signal gets passed on to a signal pad 1 12 which is connected to the printed circuit board 1 10 of the subsequence cell frame 20 via the PCB board connector. In this way, all cell voltages get passed on to the battery management system 100 in the battery lid 50, 60.

[132] Fig. 14B is an illustration of a printed circuit board 140 (small printed circuit board) according to the present invention. The small printed circuit board 140 is a single- or multilayered printed circuit board with a measurement pad 141 , a plurality of signal pads 142 and a PCB board connector 143. The small printed circuit board 140 differs from the printed circuit board 1 10 described above in that the dimension of the small printed circuit board 140 is reduced with respect to the printed circuit board 1 10. This is due to the small printed circuit board 140 being integrated into a current collector frame 90 described above. The small printed circuit board 140 is integrated into a current collector frame 90 and can measure a cell voltage with its measurement pad 141. This voltage signal gets passed on to a signal pad 142 which is connected to the printed circuit board 1 10 of the subsequence cell frame 20 via the PCB board connector.

[133] The electric connection between the measurement pad 1 1 1 , 141 of the printed circuit boards 1 10, 140 and a spring sheet 40 is established via the spring sheet tongue 42, as illustrated in Fig. 6C. Further, the printed circuit boards 1 10 of adjacent cell frames 20 are connected to each other via the plurality of signal pads 1 12 and the PCB board connector 1 13. That is, the printed circuit boards of the plurality of cell frames 20a-20e are connected to each other in series. The last printed circuit board 1 10 of the last cell frame 20e is connected to the battery management system 100 provided within a pocket 53, 63 of a lid 50, 60. In this way, the voltage of each spring sheet 40 is passed to the battery management system 100.

[134] Since the number of voltage values to be measured is larger by one than the number of cell frames 20 included in the battery system 1 , the battery system further comprises an additional printed circuit board 140, which is smaller in dimension than the printed circuit boards 1 10 described above. The additional printed circuit board 140 is held by an additional mount of the current collector frame 90 and is configured to pass a voltage signal of first, most negative side of the battery assembly to the printed circuit board 1 10 of the first cell frame 20.

[135] Figs. 15 and 16 are illustrations of the serial connection of a plurality of printed circuit boards 1 10a-1 10d, wherein the printed circuit boards 1 10a-1 10d are positioned within each of the cell frames 20a-20d holding battery cells 10. Each printed circuit board 1 10a-1 10c is connected to a printed circuit board of the next cell frame 20b-20d. The last printed circuit board 1 10d is connected to the battery management system 100.

[136] In addition to the voltage measurement performed via the measurement pads 1 1 1 connected to the spring sheet tongue 42, each cell frame 20 may include a temperature sensor connected to the printed circuit board 1 10. The printed circuit board 1 10 may further be configured to pass a temperature signal to the next printed circuit board 1 10 or to the battery management system 100. In this way, temperature measurement signals from within each cell frame 20 are passed to the battery management system 100.

[137] The temperature sensors may be positioned in direct thermal contact to one of the battery cells 10 within a cell frame 20. It is a particular advantage of the temperature sensor being positioned within the cell frame 20 over measurement of the coolant temperature, that better observation of the temperature of the battery cells 10 may be performed. Although a single temperature sensor is provided within each of the cell frames 20 in the present embodiment, a plurality of temperature sensors may be provided.

[138] According to the present embodiment, the fiberglass reinforced plastic cell frame 20 provides a very rigid structure for the mechanical integration of the battery cells 10. Further, once assembled, the coolant flow channels 31 , 32 guide the coolant in a well defined manner and thereby allow the thermal control of the battery cells 10. In particular, the coolant flows through the hollow spaces of the cell frames 20 in a parallel manner, such that the battery cells 10 are cooled homogeneously. The sealing grooves 27 of the cell frames 20 are designed to hold a seal that makes a liquid proof connection from one cell frame 20 to the next separating the interior from the exterior in order to prevent spillage of the coolant.

[139] The spring sheet 40 may be welded to the plus pole of all battery cells of the same cell frame 20, thereby connecting them in parallel. The imprinted spring arms 41 connect the battery cells 10 of consecutive cell frames 20 in series. Although in the present embodiment, the spring sheet is welded to one of the poles of all battery cells, the present invention is not limited to this, and electrical connection may be established without welding but by mechanical force only. It is a particular advantage of a welded connection that the contact resistance is reduced.

[140] The measurement pad 1 1 1 of each printed circuit board 1 10 is in contact with the positive potential of each module (cell frame 20) through the spring sheet tongue 42 allowing all potentials of the battery to be easily connected to the battery management system 100 for electric supervision.

[141] During the assembly, multiple cell frames 20 with battery cells 10, spring sheet 40 and printed circuit board 1 10 are stacked on top of each other. Thereby, the rubber seals in the sealing grooves 27 establish liquid proof connection between consecutive cell frames 20. Further, the fixing clips 25 connect adjacent cell frames 20 mechanically. Still further, the spring sheets 40 establish electrical connection between the positive potential of battery cells 10 within one cell frame 20 and the negative potential of the battery cells 10 of the next cell frame 20.

[142] For a battery system 1 as illustrated in Fig. 2 with twelve cell frames stacked on top of each other, this leads to the voltage of twelve times the voltage of a battery cell 10. In a case when the battery cells 10 are of lithium-ion type, this leads to a total voltage between the negative potential of the first cell frame 20 and the positive potential of the last cell frame 20 of 12x3.6 V = 43.2 V.

[143] Although in the above-described example, the battery system comprises twelve stacked cell frames, the present invention is not limited to this. Preferable, a battery system 1 according to the present invention comprises two or more cell frames, more preferably five to 50 cell frames and even more preferable eight to twenty-five cell frames. Further, a battery system 1 according to the present invention is not limited to the battery cells being of lithium-ion type. The battery cells may be of any type, for instance, Nickel Cadmium, Nickel metal hydride, lead acid, polymer-based or of any other type. Therefore, the voltage between the negative potential of the first cell frame 20 and the positive potential of the last cell frame 20 is a multiple of the individual voltage of the battery cells 10.

[144] It is a particular advantage of the present invention, that incoming coolant liquid is only heated by parallel battery cells 10 within a cell frame 20 rather than all of the plurality of battery cells 10, as in a case where the coolant flows through the battery housing in a serial manner. This means that the temperature difference between hottest and coldest battery cell 10 in the battery system 1 is significantly reduced.

[145] Further, from the fluid dynamic point of view all hollow spaces of the battery housing are in parallel. Thereby, the total volume throughput for a given pressure difference is significantly increased. This directly increases the cooling power of the system.

[146] Still further, the design of the printed circuit boards 1 10, their connection and the connection to the battery management system avoids not only the labor-intensive soldiering process for connection of the battery management system but also eliminates possible leaks that might occur if the cell voltages were carried to the outside of the plastic frame.

[147] The mechanical integrity of the battery system 1 may be further reinforced by the following measures. As illustrated in Fig. 2, two aluminum U-profiles may be attached to each cell frame 20a-20e and to the lids 50, 60, thereby assisting to carry any forces associated to the weight and possible acceleration of the battery system 1. Further, threaded tie rods may be inserted into the corresponding tie rod holes 28 of the lids 50, 60, the current collector frame 90 and the cell frames 20a-20e.

[148] Summarizing, the present invention relates to a modular, full enclosed, liquid cooled battery system including a plurality of battery cells and a plurality of cell frames. The cell frames are connected to each other in a serial manner, thereby forming a battery housing containing the battery cells and a coolant flow is allowed through the battery housing. Each cell frame is shaped as a one-sided open box, such that a plurality of hollow spaces is formed within the battery housing. Each cell frame has at least two liquid feedthrough openings, such that when a coolant flow is established through the battery housing, the coolant flows through the hollow spaces including the battery cells in a parallel manner.

Claims

1. A battery system comprising a plurality of battery cells (10) and a plurality of cell frames (20a-20e), the cell frames (20a-20e) being connected to each other in a serial manner, thereby forming a battery housing containing the plurality of battery cells (10) and allowing a coolant flow through the battery housing, wherein each cell frame (20a-20e) is shaped as a one-sided open box formed by a base section (23) and a plurality of side sections enclosing the interior of each cell frame (20a-20e), thereby forming a plurality of separated hollow spaces within the battery housing with the coolant flow through the hollow spaces, the hollow spaces being separated from each other by the base sections (23) of the plurality of cell frames (20a-20e), and each cell frame (20a-20e) has at least two liquid feedthrough openings (21 , 22) for establishing the coolant flow through the hollow spaces in a parallel manner.

2. The battery system according to claim 1 , wherein the at least two liquid feedthrough openings (21 , 22) of each cell frame (20a-20e) are provided at opposing positions on the base section (23) of each cell frame (20a-20e), thereby forming fluid connections between adjacent hollow spaces of the battery housing.

3. The battery system according to claim 1 or 2, wherein the plurality of battery cells (10) are provided within the hollow spaces at positions different from the positions of the at least two liquid feedthrough openings (21 ), thereby forming at least two coolant flow channels (31 , 32).

4. The battery system according to claim 3, wherein one of the coolant flow channels (31 ) is closed at a first end side of the battery housing and another one of the coolant flow channels (32) is closed at a second end side of the battery housing.

5. The battery system according to any one of claims 1 to 4, wherein each cell frame (20a- 20e) comprises a plurality of cell-openings (24) provided on the base section (23) of the cell frame (20a- 20e), each cell-opening (24) being configured to mechanically arrest one battery cell out of the plurality of battery cells (10).

6. The battery system according to any one of claims 1 to 5, further comprising a plurality of spring-sheets (40), wherein each spring sheet (40) is positioned between the base section (23) of one of the plurality of cell frames (20a-20e) and the battery cells (10) within the hollow space of the cell frame adjacent to the one of the plurality of cell frames (20a-20e), each spring sheet (40) comprises a plurality of spring arms (41 ), and the plurality of spring sheets (40) provides electrical connection between the battery cells (10) positioned within each cell frame (20a-20e) in a parallel manner, electrical connection between the battery cells (10) positioned within adjacent cell frames (20a-20e) in a serial manner; and each spring sheet (40) provides a layered structure including an inner copper layer (41 ) enclosed by two outer steel layers (42, 43).

7. The battery system according to claim 6, wherein each spring arm (41 ) is located at a position on the spring sheet (40) corresponding to a position of one of the battery cells (10) within the cell frames (20).

8. The battery system according to claim 7, wherein each spring sheet (40) is laser-welded to either one of plus and minus poles of the battery cells (10) applying a laser-welding technique.

9. The battery system according to any one of claims 1 to 8, further comprising a first lid (50) closing the battery housing on a first end side; and a second lid (60) closing the battery housing on a second end side, wherein the first lid (50), the plurality of cell frames (20a-20e) and the second lid (60) are connected to each other in a serial manner.

10. The battery system according to claim 9, wherein the first lid (50) provides a first opening (51 ); and the second lid (60) provides a second opening (61 ), wherein the first and the second openings (51 , 61 ) are provided at positions on the first and second lids (50, 60) according to the positions of the at least two liquid feedthrough openings (21 , 22) on the base sections (23) of the plurality of cell frames (20a-20e), thereby forming fluid connections according to the at least two liquid feedthrough openings (21 , 22) of the plurality of cell frames (20a-20e).

11. The battery system according to claim 9 or 10, wherein the first (50) and the second lid (60) each provide an electrical feedthrough opening (52, 62); and the battery system further comprises a first current-collector (70) providing an electric connection through the electrical feedthrough opening (52) of the first lid (50); a second current-collector (80) providing an electric connection through the electrical feedthrough opening (62) of the second lid (60).

12. The battery system according to claim 1 1 , wherein each current-collector (70, 80) comprises a layered structure including an inner copper layer enclosed by two outer steel layers.

13. The battery system according to any one of claims 9 to 12, further comprising a current collector frame (90) provided between a last cell frame (20e) out of the plurality of cell frames (20a-20e) and the second lid (60), serving to hold the current collector 70 and one printed circuit board (140) on the second end side of the battery system.

14. The battery system according to any one of claims 1 to 13, further comprising, a battery management system (100); and a plurality of printed circuit boards (110, 140) configured to provide electric potential signals to the battery management system (100), each one of the printed circuit boards (110, 140) being provided within one of the plurality of cell frames (20a-20e) or the current collector frame (90), and comprising a measurement pad (1 11 , 141 ) electrically connected to the plus or minus poles of the battery cells (10) within the one of the plurality of cell frames (20a-20e), a plurality of signal pads (112, 142) or a first connector, and a cell board connector (113, 143) configured to establish contact to the plurality of signal pads or the first connector of another printed circuit board (110, 140); wherein the printed circuit boards (110, 140) are connected to each other and to the battery management system (100) in a serial manner via the signal pads (112) or the first connectors and the cell board connectors (1 13), thereby providing each electric potential signal to the battery management system (100).

15. The battery system according to claim 14, further comprising a plurality of temperature sensors (120) provided within the plurality of cell frames (20a- 20e), wherein each of the temperature sensors (120) is configured to detect a temperature of the battery cells (10) within one of the cell frames (20a-20e), each of the temperature sensors (120) is connected to one of the printed circuit boards (1 10, 140), and the printed circuit boards (1 10) are further configured to pass a temperature signal corresponding to the detected temperature to the battery management system (100) via the signal pads (1 12) or the first connectors.

16. The battery system according to any one of claims 1 to 15, wherein the coolant flow through the battery system is established by pumping cooling liquid into one of the at least two coolant flow channels (31 , 32).

17. The battery system according to any one of claims 9, wherein the coolant flow through the battery system is established by pumping cooling liquid into one of the first opening (51 ) of the first lid (50) and the second opening (61 ) of the second lid (60).

18. The battery system according to any one of claims 1 to 17, wherein each cell frame (20a-20e) is made of fiberglass reinforced plastic.

19. The battery system according to any one of claims 1 to 18, wherein each cell frame (20a-20e) further comprises a sealing groove including a seal sealing the connection of adjacent cell frames.

20. The battery system according to any one of claims 1 to 19, further comprising a frame (130) attached to and enclosing the battery housing.