Apparatus and method for the formation of electrochemical cells

Abstract

The present invention relates to an apparatus (10) for the formation of electrochemical cells for batteries comprising a plurality of direct current power devices (20) wherein each power device (20) is configured to be electrically coupled at the output to a respective group of electrochemical cells (30) of a corresponding plurality of groups of electrochemical cells and to apply to said groups of electrochemical cells (30) a variable voltage or current such as to allow the at least partial formation of said groups of electrochemical cells (30), wherein the power devices of the plurality of power devices (20) are electrically coupled to each other in parallel and are configured to exchange direct current power with each other, the apparatus further comprising a direct current distribution bus (16) electrically coupled to each power device of the plurality of power devices (20). The present invention further describes a method for operating an apparatus (10) for the formation of a plurality of groups of electrochemical cells (30).

Description

[0001] APPARATUS AND METHOD FOR THE FORMATION OF ELECTROCHEMICAL CELLS

[0002] DESCRIPTION

[0003] The present invention has as its object an apparatus for the formation of electrochemical cells for batteries and a related method.

[0004] The present invention finds particular application in the production of secondary batteries, preferably rechargeable lithium batteries. Although specific reference will be made throughout this disclosure to lithium electrochemical cells, the teachings of the present invention also apply to the case of other secondary electrochemical cells wherein one of the cell construction processes comprises a formation process.

[0005] In the production of lithium electrochemical cells, after mechanical assembly operations of the electrochemical cells, the electrochemical cells must undergo electrical operations that lead to electrochemical phenomena inside the electrochemical cells such that a film is gradually built up that forms on the surface of the electrodes (anodes). This film is called "Solid Electrolyte Interphase" (SEI). These operations are known in the technical sector by the term "formation" of electrochemical cells. The formation cycle is the process of consecutively charging and discharging a cell after it has been assembled. During this process, a relatively low direct current is used.

[0006] Typically, the electrochemical cell formation cycle is accomplished by applying currents of 0.1 -0.2 C for predetermined time intervals separated by predetermined time intervals in which the cell does not receive current. The magnitude "C", or cell capacity, indicates the magnitude of electrical energy expressed in Ampere-hours (Ah). For example, for a cell capacity of 2 Ah, the magnitude C is 2 A. The values of the applied currents, the charging / discharging times and the number of repetitions of the various formation cycles depend on the type of battery and each battery manufacturer has developed its own "recipe" defined by the formation cycle.

[0007] In view of the times needed for formation operations which typically require a sequence of charging / discharging cycles of relatively long duration (e.g. of the order of 5-24 hours), such operations are typically performed on multiple groups of cells simultaneously. In a formation plant, groups of electrochemical cells are arranged in formation units configured to accommodate a plurality of groups of cells, for example 6 to 12, in respective housings. In the formation units, each group of cells is arranged on a respective tray housing a plurality of cells typically arranged in a matrix pattern. The group of cells is connected, for example through electrical cables, to electronic devices suitable for implementing the charging / discharging cycles of the electrochemical cells.

[0008] In the Applicant's experience, for the energy management of the formation operations, AC / DC electrical power supplies are used which are connected at the input to the service power grid and at the output to respective power devices that supply, in direct current, respective groups of cells. In order to reduce the dissipation of a part of the electrical energy, the Applicant has considered a sizing of the voltages / currents by using bidirectional AC / DC electrical power supplies in communication upstream with the AC power grid and downstream with respective DC power devices in a number equal to the AC / DC power supplies. The Applicant has however noted that, although such a configuration simplifies the layout of the system, the use of a plurality of bidirectional AC / DC electrical power supplies, typically in a number equal to the groups of electrochemical cells to be formed, considerably increases the cost of the apparatus for the formation of the electrochemical cells.

[0009] The Applicant observed that a power exchange between the direct current power devices supplying respective groups of cells would make possible a redistribution of power downstream of the electrical power supplies.

[0010] In accordance with one aspect of the present invention, an apparatus for the formation of electrochemical cells for batteries is provided.

[0011] Preferably, the apparatus comprises a plurality of direct current power devices wherein each power device is configured to be electrically coupled at the output to a respective group of electrochemical cells of a corresponding plurality of groups of electrochemical cells and to apply to said groups of electrochemical cells a voltage or a current such as to allow the at least the partial formation of said groups of electrochemical cells.

[0012] Preferably, the power devices of the plurality of power devices are electrically coupled to each other in parallel and they are configured to exchange direct current power with each other.

[0013] Preferably, the apparatus comprises a direct current distribution bus configured to transport direct current power and electrically coupled to each power device of the plurality of power devices.

[0014] Preferably, the power devices of the plurality are electrically coupled to each other in parallel at the input and are configured to exchange direct current power to each other at the input. In particular, the parallel coupling and the power exchange is at the input stage of the respective power devices.

[0015] Preferably, each power device of the plurality of power devices is an energy flow bidirectional transmission power device.

[0016] Preferably, each power device is a power converter device.

[0017] Preferably, the direct current power exchange between the power devices takes place through the distribution bus.

[0018] Preferably, the distribution bus is electrically coupled at the output to the plurality of power devices.

[0019] The direct currents of the plurality of power devices circulate in the common distribution bus putting the plurality of power devices in communication with each other.

[0020] With a bidirectional transmission between the direct current distribution bus and the respective power devices that are configured to exchange energy between them, both the absorption and the transfer of power between the power devices is possible. In general, the power needed to supply the groups of cells associated with each direct current power device approximately corresponds to the algebraic sum of the powers absorbed and transferred by each power device of the plurality.

[0021] Preferably, the distribution bus comprises a conducting bar. In one embodiment, the distribution bus comprises a first conducting bar and a second conducting bar with opposite polarities (e.g. positive and negative).

[0022] In one embodiment, the power devices are arranged aligned along a longitudinal axis. The conducting bars are arranged so as to extend along the plurality of power devices.

[0023] Preferably, the apparatus comprises at least one electrical power supply electrically coupled at the input to an electrical source and at the output to the direct current distribution bus. The electrical source may for example be an electrical source external to the apparatus.

[0024] Preferably, the at least one electrical power supply is configured to convert an electrical current at the input, having a first voltage, into an electrical current at the output, having a second voltage lower than said first voltage.

[0025] In embodiments, the at least one power supply is a plurality of electrical power supplies, each electrical power supply being electrically coupled at the input to the electrical source and at the output to the direct current distribution bus.

[0026] Preferably, the outputs of the plurality of electrical power supplies are electrically connected to the direct current distribution bus which receives at the input direct current at the second voltage.

[0027] Preferably, the at least one electrical power supply is configured for AC / DC conversion, in particular it is configured for converting alternating current electrical energy received at the input from the electrical energy source into direct current electrical energy at the second voltage.

[0028] However, it may be provided that the one or more electrical power supplies receive a first direct current voltage from a direct current source. In such an embodiment, the electrical power supplies are configured for DC / DC conversion and for providing at the output direct current power at the second voltage.

[0029] A bidirectional communication between the distribution bus and the power devices allows the power supplied by the electrical power supplies through the common distribution bus to substantially correspond to the algebraic sum of the powers received from the respective power devices. It is therefore possible to size the one or more electrical power supplies of the plurality of electrical power supplies at a lower output voltage (e.g. the second voltage), resulting in a reduction in equipment costs and consumption.

[0030] In accordance with the common meaning of the term, "algebraic sum" of power (or current or voltage) values means a sum that takes into account the sign of values that can be both positive and negative. It is assumed that the positive power values have flow of electrical energy in a direction going from the one or more power supplies to the plurality of power devices and / or from the power devices towards the groups of cells. The negative power values have flow of electrical energy in a direction from the power devices to the one or more power supplies and / or from the groups of cells to the power devices.

[0031] The Applicant has noted that, if the algebraic sum of the powers received from the distribution bus is positive at an interval of time, the "excess" power can be introduced into the AC or DC power grid that supplies the apparatus. In particular, for the purposes of redistributing excess power to the grid, it is sufficient that the DC distribution bus, in which the direct currents of the DC power devices flow in and out, is connected with a single bidirectional transmission electrical power supply. The other electrical power supplies of the plurality of power supplies can have unidirectional transmission with a consequent reduction in the overall cost of the apparatus.

[0032] According to one embodiment, a power supply of the plurality of electrical power supplies is an energy flow bidirectional transmission converter configured to supply and receive electric power to / from the distribution bus.

[0033] Preferably, each power device has a single input stage that is electrically connected with the DC distribution bus and has a plurality of output channels for electrical connection with each cell of a respective group of electrochemical cells.

[0034] Preferably, each power device is a power conversion device.

[0035] Preferably, each power device comprises a plurality of bidirectional transmission DC / DC converters in a number equal to the cells of a group of electrochemical cells. Each DC / DC converter of the plurality of DC / DC converters is electrically connected to a respective cell of the group of electrochemical cells.

[0036] Preferably, each DC / DC converter of the power device is configured to convert the electrical current at the input, having the second voltage, into an electrical current at the output, having a third voltage, lower than said second voltage and usable by each electrochemical cell.

[0037] The third voltage that supplies the cells of the groups of cells has a variable voltage value during the execution of the formation cycles. For example, the third voltage has a variable value, positive or negative, up to about 4-5 V.

[0038] The variable voltage corresponds to a positive and negative variable current that defines a sequence of charging-discharging cycles according to a scheme defined by the formation cycle and in particular by the formation protocol which may comprise a plurality of formation cycles performed in sequence.

[0039] In one embodiment, each bidirectional transmission DC / DC converter of a respective power device is a two-quadrant bidirectional converter.

[0040] Preferably, each power device of the plurality of power devices is electrically connected to a respective contact group configured to establish an electrical connection between the power device and the respective group of cells.

[0041] In one embodiment, each contact group is electrically connected to the plurality of DC / DC converters of a power device to establish an electrical connection between each cell of a group of electrochemical cells and the respective DC / DC converter.

[0042] Preferably, the apparatus comprises a drawer comprising a support structure having a length in a longitudinal axis and a plurality of housings arranged lengthwise, wherein each housing is configured to receive a respective power device of the plurality of power devices.

[0043] Preferably, each group of cells of the plurality of groups of electrochemical cells is housed on a respective cell tray.

[0044] Preferably, the cell tray is transportable into and out of a housing of the drawer.

[0045] Preferably, the direct current distribution bus comprises at least one conducting bar mounted lengthwise on the support structure of the drawer so as to extend along the plurality of power devices.

[0046] In one embodiment, the distribution bus comprises a first conducting bar and a second conducting bar with opposite polarities (e.g. positive and negative). The first and second bars are arranged so as to extend along the plurality of power devices.

[0047] In one example, the bars may be mounted parallel to each other lengthwise on the support structure.

[0048] In one example, the conducting bars are made of aluminium.

[0049] Preferably, each contact group is integrally connected to the respective power device to move together in a direction transverse to the longitudinal axis of the drawer between a first operating position and a second operating position.

[0050] In the first operating position, the contact group is not in electrical connection with the cells of the group of electrochemical cells and in the second operating operation the electrical contact group is in electrical connection with the cells of the group of electrochemical cells.

[0051] The movement of the contact group and the integral power device can be implemented by means of a lifting mechanism that operates in both directions of the direction transverse, in particular perpendicular, to the longitudinal axis of the drawer.

[0052] The present invention further relates to a method for operating an apparatus for the formation of a plurality of groups of electrochemical cells.

[0053] Preferably, the method comprises distributing power from one or more electrical power supplies at the input to a plurality of power devices.

[0054] Preferably the method comprises providing power at the input by the plurality of power devices to groups of cells of a plurality of groups of cells that are in a charging phase. Preferably, the method comprises distributing power at the output from groups of cells of the plurality of groups of cells that are in a discharging phase to the plurality of power devices.

[0055] Preferably, the value of the algebraic sum of the power at the output from the groups of cells that are in a discharging phase and of the power supplied at the input to the groups of cells that are in a charging phase corresponds to the value of the power received by the power devices from the one or more power supplies or to the value of the power received by the one or more power supplies from the power devices.

[0056] Preferably, the power devices are configured to exchange power with each other.

[0057] Preferably, distributing power from the one or more electrical power supplies at the input to the plurality of power devices comprises supplying a direct current distribution bus, wherein the distribution bus is electrically coupled to the input of each power device of the plurality of power devices and to the output of the at least one electrical power supply.

[0058] Preferably, each power device of the plurality of power devices is a bidirectional transmission power device.

[0059] An "electrochemical cell" is defined as an assembly consisting of at least one anode, one cathode, a possible dielectric material separator interposed between the anode and cathode, and an electrolyte. A battery comprises at least one electrochemical cell.

[0060] By "formation" is meant a process in which an electrochemical cell is subjected to charging / discharging / recharging cycles. The currents applied during chargingdischarging cycles, measured in Ampere, are numerically one order of magnitude less than the number expressing the total capacity in Ah of the electrochemical cell. For example, when an electrochemical cell has a capacity of 1Ah, the maximum currents applied are about 0.1 - 0.2 Ampere. The charging / discharging / recharging cycles are implemented for a time (e.g., 12-24 hours) such that to reach maximum voltage, minimum voltage, and then return the electrochemical cell to a known state of charge, typically 80%.

[0061] "Drawer" means any support structure capable of supporting one or more bodies and inserted into a housing compartment, not necessarily closed on the sides and not necessarily slidable on guides or the like in order to be extracted from the housing compartment. "Bidirectional transmission" in an electrical device means that this electrical device allows energy flows in both directions, i.e. at the input or output to / from a further electrical device. The transmission is defined between a "source" node and a "destination" node through a line on which the flows are bidirectional. Energy or power can be transmitted and received along the line between the two nodes, but not simultaneously.

[0062] In its broadest meaning, "electronic controller" or "controller" is intended to include an electronic device or system that comprises one or more controllers and / or microprocessors that can be associated with the apparatus to cooperate with each other in controlling various functions and operations of the apparatus that can be based on hierarchical control logic. The electronic controller can be part of the CPU of a computer or other systems that require complex digital control logic.

[0063] Further characteristics and advantages of the present invention will become clearer from the following detailed description of preferred embodiments thereof, with reference to the appended drawings and provided by way of indicative and non-limiting example, in which:

[0064] Figure 1 is a schematic representation of an apparatus for the formation of electrochemical cells for batteries in accordance with an embodiment;

[0065] Figure 2 is a schematic representation of a side view of a drawer configured to house a plurality of groups of electrochemical cells in accordance with an embodiment, in a first operating position;

[0066] Figure 3 illustrates the drawer of Figure 2 in a second operating position, and

[0067] Figure 4 schematically illustrates an example of a formation cycle performed on a cell of a group of cells, in accordance with an embodiment the trend of the variable current during a formation cycle.

[0068] The representations in the attached figures do not necessarily have to be understood in scale and do not necessarily respect the proportions between the various parts. In the figures, the same or similar elements of different embodiments will be indicated with the same reference numbers.

[0069] Figure 1 is a block diagram of an apparatus for the formation of electrochemical cells for batteries, in particular for rechargeable batteries, in accordance with one embodiment.

[0070] The apparatus 10 is an energy management apparatus comprising at least one electrical power supply 36-39 electrically connected at the input to an electrical energy source 15, for example an external source, such as an industrial power grid operating at a substantially constant voltage of 400 V to 800 V. The at least one electrical power supply is configured to convert an electrical current at the input, having a first voltage (for example corresponding to the voltage of an industrial power grid), into an electrical current at the output, having a second voltage, lower than said first voltage. For example, the second voltage is between 12V and 48V, for example 12V.

[0071] In the embodiment of Figure 1 , a plurality of electrical power supplies 36-39 are provided which are connected to the external electrical source 15, each electrical power supply being configured to convert electrical energy at the input having the first voltage into the second voltage. For example, each electrical power supply 36-39 is electrically connected at the input to a common alternating-current power supply line 13 connected to the external electrical source 15. Preferably, the power supplies 36-39 receive electrical energy at a same voltage.

[0072] The apparatus 10 further comprises a plurality of direct current (DC) power devices 20, hereinafter also referred to as power devices. Each power device 20 is configured to supply electrical power to a group of cells 30 of a corresponding plurality of groups of electrochemical cells. In particular, each power device 20 is electrically coupled at the output to a respective group of electrochemical cells 30.

[0073] Each power device 20 is further configured to apply to the respective group of electrochemical cells 30 a voltage or current such as to allow the at least partial formation of the cells of the group of cells.

[0074] Each power device 20 is a power conversion device configured to convert the second direct current voltage into a third direct current voltage.

[0075] In the non-limiting example, 6 power devices configured to be electrically coupled to 6 respective groups of electrochemical cells 30 are depicted.

[0076] In embodiments, the number of power devices 20 is comprised from 6 to 12, in particular from 8 to 12, for the formation of corresponding groups of electrochemical cells. In embodiments, the electrochemical cells are lithium-ion electrochemical cells, typically cylindrical cells.

[0077] The power devices 20 of the plurality are electrically coupled to each other in parallel and are configured to exchange direct current power with each other. The electrical coupling in parallel between the power devices and the power exchange take place at the input of the power devices 20.

[0078] The direct electric current at the output from the electrical power supplies 36-39 is such as to be usable by the power devices 20. In one embodiment, each electrical power supply 36-39 is an AC / DC converter configured to convert an AC voltage received from the grid into a DC voltage.

[0079] However, in a different embodiment, it may be provided that the one or more electrical power supplies 36-39 receive a first direct current voltage from a direct current source. In such an embodiment, the electrical power supplies 36-39 are configured for DC / DC conversion and for providing at the output direct current power at the second voltage.

[0080] In the following description, reference will be made, in a non-limiting way, to AC / DC electrical power supplies 36-39.

[0081] The one or more electrical power supplies 36-39 are electrically connected at the output to a direct current (DC) distribution bus 16. In particular, the respective output stage of the one or more electrical power supplies 36-39 is electrically connected to the direct current (DC) distribution bus 16 configured to receive direct current at the second voltage. The distribution bus 16 "transports" the electrical energy received at the input from the electrical power supplies 36-39 and distributes it at the output to the plurality of power devices 20.

[0082] Each power device 20 is a bidirectional transmission device of the flow of electrical energy, the flow being conceptually indicated with the bidirectional arrows 21. In particular, the energy flow at the input stage of the power device 20, which is connected to the distribution bus 16, can be used both as an input stage and as an output stage from / to the distribution bus 16.

[0083] The distribution bus 16 puts the power devices 20 in communication with each other allowing an exchange of power at the input. In this way, the power needed to supply the plurality of groups of cells 30 is substantially corresponding to the algebraic sum of the powers absorbed and transferred by the power devices 20.

[0084] For example, if in a time interval, a first power device 20 is supplying a first group of cells 30 with a positive energy balance (power transfer) while a second power device is supplying a second group of cells 30 with a negative energy balance (power absorption), it is possible for the first power device to provide the excess power to a second power device thereby reducing the overall energy requirement that must be delivered for the formation of the plurality of groups of cells 30.

[0085] In one embodiment, each power device 20 has a single input stage (not indicated in the figures) that is electrically connected with the DC distribution bus 16 and an output stage comprising a plurality of output channels (not indicated) for electrical connection with each cell of a respective group of cells 30.

[0086] Each power device 20 comprises a plurality of energy flow bidirectional transmission DC / DC converters (not depicted in the figures) in a number corresponding to the plurality of electrochemical cells of each group 30. Each DC / DC converter is configured to convert an electrical current at the input at the second voltage into an electrical current at the output at a third voltage, lower than the second voltage and usable by each cell of the group of electrochemical cells 30.

[0087] Each bidirectional DC / DC converter of a power device 20 is electrically connected to a respective cell of the respective group of electrochemical cells 30. In particular and in ways known per se, each DC / DC converter of the power device 20, is configured to inject variable voltage into the respective cell in accordance with the values set by the formation cycle.

[0088] In one embodiment, each bidirectional transmission DC / DC converter of the power device 20 is a two-quadrant bidirectional converter, that is, it is configured to reverse the current injected into the cell in the two directions, without power reversal.

[0089] By way of example, each group of cells 30 comprises 64 electrochemical cells and the power device 20, connected to the group of cells, comprises 64 output channels for supplying the individual cells with a variable voltage (third voltage).

[0090] The variable voltage corresponds to a positive and negative variable current that defines a sequence of charging-discharging cycles according to a scheme defined by the formation cycle and in particular by the formation protocol which may comprise a plurality of formation cycles performed in sequence. A formation protocol may for example comprise the repetition of 2-4 formation cycles.

[0091] Typically, the cells of the same group of electrochemical cells 30 synchronously perform the same formation cycle set by the "recipe". In this way, all the cells of a group of cells 30 start and finish the formation protocol substantially at the same time and can therefore be taken and transported to the subsequent steps of the process, for example to an "aging" phase.

[0092] If the algebraic sum of the powers received by the distribution bus 16 is positive at an interval of time, the "excess" power can be introduced into the AC power grid that supplies the apparatus 10. Therefore, for the purposes of redistributing excess power to the grid, it is sufficient that the DC distribution bus 16, in which the direct currents of the direct current power devices 20 flow in and out, is connected with a single bidirectional transmission electrical power supply.

[0093] In one embodiment, an electrical power supply 39 of the plurality of electrical power supplies 36-39 is a bidirectional transmission, indicated by double arrows 17 indicating energy exchange from / to the distribution bus 16 and from / to the electrical source 15. The other electrical power supplies 36-38 have unidirectional transmission, as indicated by arrows 19. In this way, it is possible to introduce the excess power into the power grid (conceptually indicated with the double arrow 12) without considerably increasing the costs of the apparatus.

[0094] Figure 4 is a conceptual representation of a formation cycle F comprising a sequence of charging-discharging cycles CD. The formation cycle F is represented by a variable direct current whose direction of the current varies over time. The current values can be positive, negative or zero. The zero of the current, i.e. the value of zero current, is represented by the dotted line. Each chargingdischarging cycle of the formation cycle comprises a charging step C followed by a discharging step D, wherein the charging step and the discharging step have opposite current intensity. In the example, a positive current above the zero line and a negative current below the zero line are assumed in a non-limiting manner. The current, positive or negative, intercepts the zero at current reversal points.

[0095] The electrical connection between a power device 20 and the respective group of cells 30 may be implemented in ways known per se, for example by means of electrical wires connecting each cell of a group of cells 30 to the output channels of the respective power device 20.

[0096] In one embodiment, each power device 20 is electrically connected to a respective electrical contact group 25, hereinafter also referred to as a contact group, configured to establish an electrical connection between the power device 20 and the respective group of cells 30.

[0097] The contact group 25 is electrically connected to a respective power device 20. In particular, the contact group is configured to be electrically connected to the plurality of bidirectional DC / DC converters of the power device 20 to establish an electrical connection between each cell of the group of electrochemical cells and a respective DC / DC converter.

[0098] In accordance with one embodiment, the contact group 25 is integrally connected to the respective power device 20. An electronic controller 50 is operatively connected to the plurality of power devices 20 and is programmed to have each power device perform the formation protocol (e.g., one or more formation cycles) on the cells of the respective group of cells 30.

[0099] Each power device 20 comprises a control unit (not indicated in the figures) operatively connected to the electronic controller 50 and configured to perform the formation cycles. The control unit can also perform functions of checking the integrity of the different electronic components and cells. Temperature detectors and / or meters of derived magnitudes such as the capacity may be present in each power device 20. The information collected by the control units is transmitted to the electronic controller 50 for the purpose of general supervision of the apparatus.

[0100] In one embodiment, the electronic controller 50 is further connected to the distribution bus for a control of the voltage circulating within the bus and to the plurality of electrical power supplies 36-39 (only the control line to the power supply 36 is indicated in the Figure).

[0101] In one embodiment, the plurality of power devices 20 is housed in a drawer 40 (Figures 2 and 3). The drawer 40 comprises a support structure 27 having a length along a longitudinal direction Y.

[0102] The drawer 40 may be arranged in a compartment of a more complex structure (not illustrated), for example a formation rack, comprising a plurality of compartments for housing respective drawers. The drawer 40 comprises a plurality of housings 24 equal to the number of the power devices 20 of the apparatus 10. The power devices 20 are configured to perform the operations of forming respective plurality of electrochemical cells 30.

[0103] The plurality of power devices 20 are housed in a corresponding plurality of housings 24.

[0104] The groups of electrochemical cells 30 are housed on respective cell trays 35, wherein each cell tray 35 is transportable into and out of the drawer 40. The cell trays 35 are arranged at a respective housing 24 of the drawer 40. In particular, the cell trays 35 are arranged near a respective electrical contact group 25, for the electrical coupling of the group of cells 30 with a respective power device 20. For example, the cell trays 35 are arranged on two side guides 32 connected to the support structure 27.

[0105] The cell trays 25 are configured so as to allow to the respective contact groups 25 an electrical connection with the respective groups of cells 30.

[0106] In one embodiment, each electrical contact group 25 is integral with a respective power device of the plurality of power devices 20.

[0107] Each electrical contact group 25, together with the integral power device 20, is configured to move in a direction transverse, in particular in a direction perpendicular Z, to the longitudinal axis Y, between a first operating position and a second operating position. In the first operating position, the contact group 25 is not electrically coupled to a group of electrochemical cells 30 (Figure 2) and in the second operating operation the contact group is electrically coupled to the cells of the group of electrochemical cells (Figure 3).

[0108] To this end, a lifting mechanism, not illustrated and indicated in Figure 2 with a double arrow 34, can be provided at each housing 24 for moving the contact group 25 along the Z axis.

[0109] In the non-limiting example of Figures 2 and 3, five of the six housings 24 of the drawer 40 are occupied by respective cell trays 35. Figure 2 can represent a configuration in which the drawer receives, in the first five housings 24 (defined from the left side of the drawer), a respective cell tray 35, not yet electrically coupled to the respective contact group (first operating condition). In Figure 3, the contact groups 25 of the groups of cells arranged at the first five housings are in the second operating position, i.e. they are electrically connected to a respective group of cells. The contact group 25 arranged in the sixth housing is in the first operating position. For example, it is waiting to receive a tray of cells 35.

[0110] When a group of cells 30 has completed the formation cycle, the corresponding contact group 25 is disconnected from the cell tray 35 and the latter can be transported to a subsequent processing step, for example to an aging step.

[0111] Each power device 20 is electrically coupled to the distribution bus 16. The distribution bus 16 is mounted lengthwise on the support structure 27 of the drawer along the longitudinal axis Y so as to extend along the plurality of power devices 20.

[0112] The distribution bus 16 comprises at least one conducting bar configured to transport current and extending along the longitudinal axis Y.

[0113] In the embodiment of Figures 2 and 3 the distribution bus comprises a positive polarity conducting bar and a negative polarity conducting bar 16a, 16b, wherein the conducting bars are mounted parallel to each other lengthwise on the support structure 27 of the drawer 40.

[0114] The conducting bars 16a, 16b are for example made of aluminium.

[0115] In the non-limiting example of the figures, the conducting bars 16a, 16b are arranged on a first side (along the axis Y) of the drawer 40.

[0116] An arrangement of the power devices 20 side by side can promote a power exchange between the devices 30 without significant voltage losses.

[0117] In one embodiment, each power device 20 is connected to the conducting bars 16a, 16b by means of a respective electrical cable 23a, 23b configured to supply the input stage of each power device.

[0118] The provision of a common distribution bus arranged near the power devices allows a simplification of the arrangement of the apparatus as the power devices are supplied through an electrical connection with the conducting bars that are arranged near the power devices.

[0119] The distribution bus 16 is electrically connected to the one or more electrical power supplies 36-39 (not illustrated in Figures 2 and 3). The power supplies 36- 39 can be arranged near the drawer 40, for example at the compartment housing the drawer, and be connected, by means of an AC plug (not illustrated), to the socket 15 of a service power grid supplying AC voltage as an external electrical source 12.

[0120] The arrangement of the power devices 20 inside the drawer 40 represented in Figures 2 and 3 is not to be considered as limiting. For example, the power devices 20 could be arranged inside a respective housing 24 upside down with respect to what is shown in the aforementioned Figures so as to have the respective contact group 25 below the power device 20. In this alternative configuration, the trays 35 enter and exit the drawer 40 in proximity to the respective contact groups 25, in a space of the housing 24 arranged below the contact group 25. Similarly, whether the contact groups 25 face upwards or downwards, with reference to the direction Z, the distribution bus 16 can be arranged in a different position of the support structure 27 of the drawer 40 or not be part of the drawer structure, but be mounted near the drawer 40 inside the compartment housing the latter.

[0121] The person skilled in the art will recognize that it is possible to combine the various features of the above-described embodiments to obtain further embodiments, all falling within the scope of the present invention as defined by the following claims.

Claims

CLAIMS1. Apparatus (10) for the formation of electrochemical cells for batteries comprising a plurality of direct current power devices (20) wherein each power device (20) is configured to be electrically coupled at the output to a respective group of electrochemical cells (30) of a corresponding plurality of groups of electrochemical cells and to apply to said groups of electrochemical cells (30) a variable voltage or current such as to allow at least the partial formation of said groups of electrochemical cells (30), wherein the power devices of the plurality of power devices (20) are electrically coupled to each other in parallel and they are configured to exchange direct current power with each other, the apparatus (10) further comprising a direct current distribution bus (16) electrically coupled to each power device of the plurality of power devices (20).

2. Apparatus according to claim 1 , wherein the direct current power exchange between the power devices (20) takes place through the distribution bus (16).

3. Apparatus according to claim 1 or 2, wherein the power devices (20) of the plurality of the power devices (20) are electrically coupled to each other in parallel at the input and are configured to exchange direct current power to each other at the input.

4. Apparatus (10) according to one or more of the preceding claims, wherein each power device of the plurality of power devices (20) is a bidirectional transmission power device.

5. Apparatus (10) according to one or more of the preceding claims, wherein each power device (20) has a single input stage that is electrically connected with the distribution bus (16) and has a plurality of output channels for electrical connection with each cell of a respective group of electrochemical cells (30).

6. Apparatus (10) according to claim 5, when dependent on claim 3, wherein the input stage of each power device (20) is configured to be used both as an output stage and as an input stage to / from the distribution bus (16).

7. Apparatus (10) according to any one of the preceding claims, wherein the power distribution bus (16) comprises at least one conducting bar (16a, 16b) electrically coupled to the power devices (20).

8. Apparatus (10) according to one or more of the preceding claims,comprising at least one electrical power supply (36-39) electrically coupled at the input to an electrical source (12) and at the output to the direct current distribution bus (16), wherein the at least one electrical power supply (36-39) is configured to convert an electrical current at the input, having a first voltage, into an electrical current at the output, having a second voltage lower than said first voltage.

9. Apparatus (10) according to claim 8, wherein the at least one power supply (36-39) is a plurality of power supplies (36-39) electrically coupled at the input to the electrical source (12) and at the output to the direct current distribution bus (16).

10. Apparatus (10) according to claim 9, wherein an electrical power supply (39) of the plurality of electrical power supplies (36-39) has bidirectional current transmission and is configured to supply and receive electrical power to / from the direct current distribution bus (16).11 . Apparatus (10) according to claim 3 or 4 to 10 when dependent on claim 3, wherein each power device (20) comprises a plurality of bidirectional transmission DC / DC converters, wherein each DC / DC converter of the plurality of DC / DC converters is electrically connected to a respective cell of each group of electrochemical cells (30) and wherein each DC / DC converter is configured to convert the electrical current at the input, having the second voltage, into an electrical current at the output, having a third voltage, lower than said second voltage.

12. Apparatus (10) according to one of the preceding claims, wherein each power device (20) is electrically connected to a respective contact group (25) configured to establish an electrical connection between the power device (20) and the respective group of cells (30).

13. Apparatus (10) according to one of the preceding claims, comprising a drawer (40) comprising a support structure (27) having a length in a longitudinal axis (Y) and comprising a plurality of housings (24) arranged lengthwise, each housing (24) being configured to receive a respective power device (20) of the plurality of power devices.

14. Apparatus (10) according to claim 13, wherein the direct current distribution bus (16) comprises at least one conducting bar (16a, 16b) mounted lengthwise on the support structure (27) of the drawer (40) so as to extend along the plurality of power devices (20).

15. Apparatus (10) according to claim 13 or 14, wherein each group of cells (30)of the plurality of groups of electrochemical cells (30) is housed on a respective cell tray (35), wherein the cell tray is transportable in and out of a housing (24) of the drawer (40).

16. Apparatus (10) according to claim 12 or from claims 13 to 15 when dependent on claim 12, wherein each contact group (25) is integrally connected to the respective power device (20) to move together in a direction transverse (Z) to the longitudinal axis (Y) between a first operating position and a second operating position by means of a lifting mechanism (34), wherein in the first operating position the contact group (25) is not electrically connected to the cells of the group of electrochemical cells (30) and in the second operating position the electrical contact group (25) is in electrical connection with the cells of the group of electrochemical cells (30).

17. Method for operating an apparatus (10) for the formation of a plurality of groups of electrochemical cells (30), the method comprising: distributing, from one or more electrical power supplies (36-39), power at the input to a plurality of power devices (20) configured to exchange electrical power with each other; supplying, by the plurality of power devices, power at the input to groups of cells of a plurality of groups of cells (30) that are in a charging phase, and distributing power at the output from groups of cells of the plurality of groups of cells (30) that are in a discharging phase to the plurality of power devices (20), wherein the value of the algebraic sum of the power at the output from the groups of cells (30) that are in a discharging phase and of the power supplied at the input to the groups of cells (30) that are in a charging phase corresponds to the value of the power received by the power devices (20) from the one or more power supplies (36-39) or to the value of the power received by the one or more power supplies (36-39) from the power devices (20).

18. Method according to claim 17, wherein distributing power from the one or more electrical power supplies (36-39) at the input to the plurality of power devices (20) comprises supplying a direct current distribution bus (16), wherein the distribution bus (16) is electrically coupled to the input of each power device (20) of the plurality of power devices and to the output of the at least one electrical power supply (36-39).

19. Method according to one of claims 17 or 18, wherein each power device of the plurality of power devices (20) is a bidirectional transmission power device.

20. Method according to one of claims 17 to 19, wherein exchanging direct current power between the power devices (20) takes place through the distribution bus (16).

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