DE202023100580U1 - traction battery for a vehicle - Google Patents

Abstract

Traction battery (100) for a vehicle, the traction battery (100) having cells (102) of a first cell type and at least one second cell type, the cells (102) of the different cell types within the traction battery (100) being electrically connected.

Description

technical field

The present invention relates to a traction battery for a vehicle.

State of the art

The present invention is described in the following mainly in connection with traction batteries for electric vehicles.

In an electrically powered vehicle, drive energy can be stored in a traction battery. The traction battery consists of a large number of battery cells that are electrically connected to one another. The battery cells can also be combined to form battery modules and be electrically connected to one another within the battery modules, in which case a plurality of battery modules are then electrically connected to one another within the traction battery.

Different vehicle types have different requirements for the battery cells used. Therefore, battery cells optimized for the respective requirements are used in different vehicle types. For example, the battery cells can be optimized for maximum capacity for a first vehicle type and for maximum performance for a second vehicle type. For a third type of vehicle, the battery cells can be optimized for maximum service life.

Description of the invention

It is therefore an object of the invention to provide an improved traction battery for a vehicle using means that are as simple as possible in terms of design. An improvement here can concern, for example, the use of cells that can be standardized for different applications.

The object is solved by the subject matter of the independent claim. Advantageous developments of the invention are specified in the dependent claims, the description and the accompanying figures.

In the approach presented here, different types of, in particular, standardized cells are combined with one another in a traction battery. The cells can be accumulators and/or capacitors, in particular supercapacitors. The different cell types within the traction battery or within a battery module of the traction battery are connected to one another in an electrically conductive manner.

With the approach presented here, the traction battery can combine the properties of the different cell types. Cells of one cell type can play to their strengths where cells of the other cell type may have weaknesses. By mixing cell types, different standardized cells can be used to compose a traction battery with desired properties.

A traction battery for a vehicle is proposed, the traction battery having cells of a first cell type and at least one second cell type, the cells of the different cell types being electrically connected within the traction battery.

A traction battery can store drive energy for an electric drive of a vehicle. The traction battery can also store recovered braking energy and provide it again as drive energy. The traction battery can have a housing in which many cells are protected from environmental influences. Alternatively, the cells can also be distributed over the vehicle. The traction battery can have a temperature control system for temperature control of the cells. The traction battery can have a common positive pole and a common negative pole for all cells combined in the traction battery. The traction battery can have a battery management system, e.g. to compensate for different aging states of the cells or to balance the charge states of several cells.

The cells can be different. Cells can be accumulators or capacitors. In particular, the capacitors can be supercapacitors. For example, the cells can have different cell chemistries, i.e. they can differ, for example, with regard to the materials that act as an electrolyte, with regard to the materials used on the electrodes, etc. Alternatively or in addition, cells can differ with regard to their structural design, for example with regard to their external dimensions, with regard to the areas and/or thicknesses of the electrodes, membranes, etc. accommodated therein, and/or with regard to other geometric properties. The different cells can also have different electrical properties.

For example, cells of a first cell type can be high-performance cells, while cells of a second cell type can be high-energy cells. Alternatively or additionally, the cells of the first cell type can have a first cell chemistry, while the cells of the second cell type have an alternative cell chemistry.

The cells of the different cell types can be connected in parallel. In the case of a parallel connection, all the positive poles of the cells and all the negative poles of the cells can be connected to one another in an electrically conductive manner. The parallel connection can therefore have a common positive pole and a common negative pole. As a result, all positive poles are at the same electrical potential. Likewise, all negative poles are at the same electrical potential. When connected in parallel, the same electrical voltage can be applied to all cells. Different electrical current flows can flow through the different cells.

The cells of the different cell types in the parallel connection can have a predefined ratio. For example, one cell type can be arranged in the parallel circuit more often than another cell type. The cells of the different cell types can have the same ratio. Then there can be the same number of cells of each cell type in the parallel connection.

At least two parallel circuits can be connected as a series circuit. In a series connection, a positive pole of a parallel circuit is connected to a negative pole of the next parallel circuit. As a result, the same electric current flows through all parallel circuits. A part of a total electrical voltage across the series circuit is present at each parallel circuit. A group of cells connected in parallel can be referred to as a cell block. Then cell blocks are electrically connected in series as a series connection.

The cells of the different cell types can be connected in series. In a series circuit, the positive pole of one cell is connected to the negative pole of the next cell. As a result, the same electric current flows through all cells. A part of a total electrical voltage is applied to each cell via the series circuit.

The cells of the different cell types in the series connection can have a predefined ratio. For example, one cell type can be arranged in the series connection more often than another cell type. The cells of the different cell types can have the same ratio. Then the same number of cells of each cell type can be connected in series. Likewise, cell blocks of cells connected in parallel in the series connection can have a predefined ratio.

The cells of the different cell types can be connected in series in a predefined order. The order in which the cells are connected in series allows the properties of the different cells to be strengthened or weakened. Likewise, cell blocks of cells connected in parallel can be connected in series in a predefined order.

At least two series circuits can be connected as a parallel circuit. In the case of a parallel circuit, all the positive poles of the series circuits and all the negative poles of the series circuits can be connected to one another in an electrically conductive manner. The parallel connection can therefore have a common positive pole and a common negative pole. As a result, all positive poles are at the same electrical potential. Likewise, all negative poles are at the same electrical potential. When connected in parallel, the same electrical voltage can be applied to all series connections. Different electrical current flows can flow through different series connections. The series circuits in the parallel circuit can have a predefined ratio.

At least one of the series circuits can be connected in parallel to the other series circuits via a DC voltage converter. A DC converter can change an electrical voltage. As a result, a different voltage can be applied to at least one of the series circuits. For example, the series circuit connected via the DC voltage converter can consist of the cells of the other cell type.

For example, high-performance cells can be connected to high-energy cells. This combination allows the traction battery to have high performance and a large energy content. The positive properties can complement each other.

The traction battery can have cells of a third cell type. A third cell type can have other desired properties that can be advantageously combined with the properties of the other cell types. The third cell type can have the properties, for example, due to a third cell chemistry.

character list

• 1 bis 2 zeigen Traktionsbatterien gemäß Ausführungsbeispielen.

Advantageous exemplary embodiments of the invention are explained below with reference to the accompanying figures. Show it:

• 1 until 2 show traction batteries according to embodiments.

The figures are schematic representations and only serve to explain the invention. Elements that are the same or have the same effect are provided with the same reference symbols throughout.

Detailed description

1 10 shows a traction battery 100 according to an exemplary embodiment. In the traction battery 100, cells 102 of different cell types are electrically connected to one another.

At least three cells 102 are connected in parallel to form a cell block 104 here. In this case, two of the cells 102 are cells 102′ of a first cell type and one of the cells 102 is a cell 102″ of a different second cell type.

In one exemplary embodiment, a multiplicity of cells 102 are connected in parallel to the cell block 104, two thirds of the cells 102 being cells 102' of the first cell type and one third of the cells 102 being cells 102'' of the second cell type.

In one exemplary embodiment, at least three cells 102 are connected in parallel to cell block 104, with at least one of cells 102 being a cell 102` of the first cell type, at least one of cells 102 being a cell 102" of the second cell type, and at least one of cells 102 being a Cell of another third cell type is.

In one exemplary embodiment, a plurality of such cell blocks 104 each consisting of at least three cells 102 with different cell types are connected in series as a series circuit 106 in order to form traction battery 100 .

In one exemplary embodiment, a plurality of such series circuits 106 each consisting of at least two cell blocks 104 are connected up as a parallel circuit 108 in order to form the traction battery 100 .

2 10 shows a traction battery 100 according to an exemplary embodiment. A plurality of cells 102 are connected in series here to form a series circuit 106 . A first proportion of the cells 102 connected in series are cells 102′ of a first cell type and a second proportion of the cells 102 connected in series are cells 102″ of a second cell type.

In one embodiment, a third portion of the series-connected cells 102 are cells of a third cell type.

In one exemplary embodiment, at least two such series circuits 106 are electrically connected in parallel to form a parallel circuit 108 in order to form the traction battery 100 .

In one embodiment, the cells 102 of at least one series circuit 106 are cells 102′ of the first cell type and the cells 102 of at least the other series circuit 106 are cells 102″ of the second cell type.

In one exemplary embodiment, at least one of the series circuits 106 is electrically connected in parallel with the other series circuits 106 via a DC/DC converter 110 in order to form the traction battery 100 .

In one exemplary embodiment, the cells 102 of the different cell types are electrically connected to form the series circuits 106 in a defined sequence. The sequence from series circuit 106 to series circuit 106 can differ or be identical.

In the following, possible configurations of the invention are summarized again or presented with a slightly different choice of words.

A multi-cell battery for electric and hybrid vehicles is presented.

Battery cells can be optimized with regard to various parameters. For example, battery cells can be classified in terms of their gravimetric power density [W/kg], their volumetric power density [W/I], their gravimetric energy density [Wh/kg], their volumetric energy density [Wh/I], their cyclic aging [number of charging and discharging Cycles at a defined depth of discharge and limit for residual capacity and/or increase in internal resistance], their calendar aging [age in years at a defined limit for residual capacity and/or increase in internal resistance], their self-discharge [loss of capacity in % per year], their costs [€/kWh for materials and production], their operating temperature ranges [°C] or their safety [hazard level 0-7 in defined misuse tests].

Current batteries usually only use one type of cell. The cell used is usually specially developed/adapted for the battery application. Standardized cells are not used because they usually do not meet all the required parameters

A battery cell is therefore not optimally designed in all parameters. They are usually optimized in terms of performance or energy. To get acceptable values for all required parameters in one To achieve battery, the approach presented here combines different cells, which are optimized in terms of performance and energy, energy and safety or energy and costs.

To do this, different cell types are connected in a battery. In one exemplary embodiment, when two cell types are connected, cell blocks are formed in which a first number of cells of the first type is connected in parallel with a second number of cells of the second type. The cell blocks are connected in series.

In one embodiment, first cell blocks are formed with a first number of cells of the first type. The first cell blocks are connected in series. Second cell blocks are formed with a second number of cells of the second type. The second cell blocks are also connected in series. The serial interconnections of the first cell blocks and second cell blocks are interconnected in parallel.

In one embodiment, first cell blocks are formed with a first number of cells of the first type. The first cell blocks are connected in series. Second cell blocks are formed with a second number of cells of the second type. The second cell blocks are also connected in series. The serial interconnections of the first cell blocks and second cell blocks are coupled via converters (DC/DC converters).

In one embodiment, three cell types are interconnected. Cell blocks are formed in which a first number of cells of the first type is connected in parallel with a second number of cells of the second type and a third number of the third type. The cell blocks are connected in series.

In one embodiment, first cell blocks are formed with a first number of cells of the first type. The first cell blocks are connected in series. Second cell blocks are formed with a second number of cells of the second type. The second cell blocks are also connected in series. Third cell blocks are formed with a third number of cells of the third type. The third cell blocks are also connected in series. The serial interconnections of the first cell blocks, second cell blocks and third cell blocks are interconnected in parallel.

In one embodiment, first cell blocks are formed with a first number of cells of the first type. The first cell blocks are connected in series. Second cell blocks are formed with a second number of cells of the second type. The second cell blocks are also connected in series. Third cell blocks are formed with a third number of cells of the third type. The third cell blocks are also connected in series. The serial interconnections of the first cell blocks, second cell blocks and third cell blocks are coupled via one or two converters (DC/DC converters).

A combination of more than three cell types is also possible. In practice, however, the effort increases with an increasing number of cell types (for development (coordination of the cells to each other), availability and logistics, ...) and economies of scale with lower quantities of the individual cell types decrease.

The approach presented here can be used in battery systems. The price of the battery systems can be lowered. No battery-specific cells need to be specified and tested. Cells from different suppliers can be used and combined.

By cleverly combining cells, better battery parameters can be achieved than with a cell specific to a battery. In addition, battery variants with different performance and capacity values can be formed more easily without having to develop new cells.

In a preferred embodiment, high-energy cells of the first type and high-performance cells of the second type or high-energy cells of the first type and high-energy cells of the second type or high-performance cells of the first type and high-performance cells of the second type in standardized formats (including round cells 18650, 2170, 4680) are one in all battery optimized for the required parameters, if possible without the use of expensive DC/DC converters.

For example, "NMC High Energy" can be interconnected with "NMC High Power". "NMC High Energy" can also be interconnected with "LFP High Energy". "NMC High Energy" can also be interconnected with "LFP High Power". "NMC High Power" can also be interconnected with "LFP High Energy". "NMC High Power" can also be interconnected with "LFP High Power". Likewise, "NMC High Energy" can be interconnected with "LiC High Power". "NMC High Energy" can also be interconnected with "NMx High Energy". "NMC High Energy" can also be interconnected with "NA+ High Energy". "NMx High Energy" can also be interconnected with "NA+ High Energy".

NMx stands for nickel manganese (without cobalt), NMC for nickel manganese cobalt, NCA for lithium cobalt aluminum oxide, LFP for lithium iron phosphate, LMP for lithium manganese phosphate, LMFP for lithium manganese iron phosphate, LCO for lithium cobalt oxide, LiC for lithium ion capacitor, LTO for lithium titanate (oxide), and LiS for lithium sulfur.

In a further preferred embodiment, cells of the first type and cells of the second type with similar OCV characteristics are used in order to minimize the equalizing currents between cells connected in parallel and to be able to use the largest possible SOC range of both cell types. The number of cells of the first type in relation to the number of cells of the second type is chosen in such a way that the desired charging currents of the battery are achieved. The desired charging current of the battery results from ((charging current of the cell of the first type)*(number of parallel cells of the first type)+(charging current of the cell of the second type)*(number of parallel cells of the second type))/( (number of parallel cells of the first type)+(number of parallel cells of the second type)).

The cells of the first type and of the second type are arranged in such a way that the equalizing currents are minimized in the case of different internal resistances of cells of the first type to cells of the second type via the parallel interconnections. The cells of the first type and the second type are arranged in such a way that the thermal behavior of the battery pack is optimized during operation. Cells with a lower internal resistance heat up the neighboring cells less.

The cells of the first type and the second type are arranged in such a way that thermal runaway (thermal propagation) is avoided in the event of thermal runaway of a single cell (thermal runaway). Cells with lower energy content usually show a lower energy output in the event of a thermal runaway.

In one embodiment, this is achieved by an arrangement with the same number of cells of the first type and of the second type.

In one embodiment, this is achieved by an array having twice as many cells of the first type as cells of the second type.

Since the devices and methods described in detail above are exemplary embodiments, they can be modified to a large extent in the usual manner by a person skilled in the art without departing from the scope of the invention. In particular, the mechanical arrangements and the size ratios of the individual elements to one another are merely exemplary.

Reference List

100

traction battery

102

cell

104

cell block

106

series connection

108

parallel circuit

110

DC converter

Claims (11)

Traction battery (100) for a vehicle, the traction battery (100) having cells (102) of a first cell type and at least one second cell type, the cells (102) of the different cell types within the traction battery (100) being electrically connected. Traction battery (100) according to claim 1 , in which the cells (102) of the different cell types are connected in a parallel circuit (108). Traction battery (100) according to claim 2 , in which the cells (102) of the different cell types in the parallel circuit (108) have a predefined ratio. Traction battery (100) according to one of claims 2 until 3 , in which at least two parallel circuits (108) are connected as a series circuit (106). Traction battery (100) according to one of the preceding claims, in which the cells (102) of the different cell types are connected in a series circuit (106). Traction battery (100) according to claim 5 , in which the cells (102) of the different cell types in the series connection (106) have a predefined ratio. Traction battery (100) according to one of Claims 5 until 6 , in which the cells (102) of the different cell types are connected in series in a predefined order. Traction battery (100) according to one of Claims 5 until 7 , in which at least two series circuits (106) are connected as a parallel circuit (108). Traction battery (100) according to claim 8 , in which at least one of the series circuits (106) is connected in parallel to the other series circuits (106) via a DC/DC converter (110). Traction battery (100) according to one of the preceding claims, in which high-performance cells are connected to high-energy cells. Traction battery (100) according to one of the preceding claims, with cells (102) of a third cell type.

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