Method and test bench for determining a pressure and a temperature to be applied to a battery cell to maximize its performance

Abstract

The invention relates to a method and a test bench for determining a pressure and a temperature to be applied to a battery cell to maximize its performance according to different given operating modes, the method comprising: arranging battery cells in hermetically sealed housings; applying isostatic pressure to the battery cells by means of a fluid contained in the housing; performing multiple cycling sequences on the battery cells by applying conditions which represent different operating modes, and by varying the pressure and / or the temperature of the fluid, while monitoring the performance of the battery cells by collecting data on the operation thereof; and determining the pressure and the temperature to be applied to the cells, via the fluid, for each of the operating modes from the collected data.

Description

[0001] METHOD AND TEST BENCH FOR DETERMINING A PRESSURE AND TEMPERATURE TO APPLY TO A BATTERY CELL TO MAXIMIZE ITS PERFORMANCE

[0002] DOMAIN

[0003] This disclosure relates to a method for determining a pressure and temperature to be applied to a battery cell to maximize its performance according to its use, as well as a test bench to carry out the method.

[0004] STATE OF THE ART

[0005] Determining the optimal pressure and temperature conditions for battery cell operation can improve battery performance, safety, and lifespan. Several experimental methods exist to assess the impact of pressure and temperature on battery performance.

[0006] In particular, excessively high temperatures can promote secondary reactions, accelerate electrode aging, and increase the risk of thermal failure. Conversely, excessively low temperatures reduce ion diffusion, which decreases capacity and increases the internal resistance of the battery cell.

[0007] Similarly, the pressure applied to a battery cell influences electrode density, the contact between active particles, and the quality of the interfaces between the electrodes and the electrolyte, which in turn affects electronic and ionic conductivity. Appropriate pressure can also prevent or limit cell volume variation and reduce the risk of electrode delamination.

[0008] To cycle battery cells under different pressure conditions, mechanical, pneumatic, or hydraulic devices can be used to apply pressure to the battery surface or to vary its temperature. These devices allow researchers to study the impact of pressure on electrochemical properties, swelling, and material degradation.

[0009] However, these devices or instruments do not allow for the safe testing of battery cells at very high pressure values ​​and / or by applying uniform pressure across all surfaces of the battery cell and / or by being able to vary

[0010] Robic File No.: 22186-0080

[0011] HQ File No.: 0886-PCT - 1 - pressure and temperature simultaneously. Furthermore, research into new cell chemical compositions is evolving rapidly, and companies conducting this research lack effective means to study the behavior of different chemical compositions. In some cases, promising chemical compositions may be discarded due to a lack of resources to identify their operating parameters or the type of encapsulation required for a given chemical composition.

[0012] In light of the above, there is therefore a need for a test bench and an associated method to resolve at least one of the problems and / or limitations discussed above.

[0013] SUMMARY

[0014] According to one aspect, a method is described. The method allows for the determination of an optimal pressure and / or temperature to be applied to a battery cell to maximize its performance in a given operating mode. The method comprises the following steps: a) placing the battery cell in a hermetically sealed case, the case including a fluid inlet port and a fluid outlet port; b) applying isostatic pressure to the battery cell using a fluid contained within the case; c) performing several cycling sequences of the battery cell by applying conditions representative of the operating mode and varying the fluid pressure and / or temperature, each cycling sequence being performed at a given pressure and temperature; d) during the cycling sequences, monitoring the performance of the battery cell by collecting data on its operation.and e) once the cycling sequences are completed, determine the optimal pressure and temperature to be applied to the battery cell from the collected data, the optimal pressure and temperature being those that maximize battery performance for said operating mode.

[0015] In some embodiments, the given operating mode is one operating mode among several operating modes, including: a fast-charging operating mode or a

[0016] Robic File No.: 22186-0080

[0017] HQ File No.: 0886-PCT - 2 - variable rate charging sequence, a pulsed charging or discharging mode of operation, a resting or storage mode at very cold or very hot ambient temperature, a charging or discharging mode at very cold or very hot ambient temperature.

[0018] In some embodiments, the method includes repeating steps a) to e) for each of the different operating modes, the method enabling the determination, for each operating mode, of the optimal pressure and optimal temperature to be applied to the battery cell.

[0019] In some embodiments, in step c), the representative conditions of the operating mode to be applied include a current consumed corresponding to a discharge, a current injected corresponding to a charge, an ambient temperature, a battery charge level (SoC), a battery deterioration state (SoH), and a quantity of charges transferred.

[0020] In some embodiments, the method includes repeating steps a) and e) for different battery cells, the cycling sequences being carried out in parallel for the different battery cells, each battery cell having a specific size and chemical composition, the method enabling the determination of the optimal pressure and optimal temperature for each of the different batteries, in one or more modes of operation.

[0021] In some embodiments, the method includes, during the cycling sequences, placing the housing in an oven to replicate an outside temperature or an outside temperature range.

[0022] In some embodiments, monitoring battery cell performance includes monitoring at least one of the following criteria: the evolution of its nominal capacity over cycles, its nominal capacity as a function of charge and discharge rates, its nominal capacity as a function of different operating temperatures and pressures, the evolution of its internal resistance, its coulombic efficiency, its temperature.

[0023] In some embodiments, varying the fluid pressure and / or fluid temperature includes varying the fluid temperature with a housing fluid heating and / or cooling module.

[0024] Robic File No.: 22186-0080

[0025] HQ File No.: 0886-PCT - 3 - According to another aspect, a method is provided for operating a battery cell test bench to determine the respective pressures and temperatures to be applied according to different operating modes. The method comprises the following steps: arranging the battery cells in test bench housings, the housings being hermetically sealed, each housing containing one battery cell and including electrical connection terminals, a fluid inlet port and a fluid outlet port; injecting, by means of a test bench control system connected to the fluid inlet and outlet ports of the housings, a fluid applying isostatic pressure to the battery cells; applying, by means of a cycling device connected to the housing connection terminals, cycling sequences to the cells, the cycling sequences corresponding to the different operating modes;During the application of the cycling sequences, vary the temperature and / or pressure of the fluid in each of the housings by the control system, independently from one housing to another, according to different pressure and temperature profiles; detect, by sensors connected to the housings, parameters indicative of the performance of the battery cells; collect, by a controller connected to the sensors, data derived from said parameters, and determine from said data, by the same or by another controller, for each of the operating modes, a pressure and a temperature to be applied to a given battery cell to maximize its performance.

[0026] In some embodiments, the step of applying the cycling sequences corresponding to distinct modes of operation includes: applying to at least one of the cells, a continuous power return, corresponding to a battery recharge; and applying to at least one other of the cells, at least one cycle among: an alternation of power demand and power return, corresponding to accelerations followed by braking during driving; no power demand or return, corresponding to a battery.

[0027] In some embodiments, applying the cycling sequences corresponds to making a call or an injection of power on each battery according to power profiles, or equivalent voltage or current profiles, corresponding to real driving situations previously recorded.

[0028] In some embodiments, at least two of the cells have a distinct size and / or chemical composition.

[0029] In some embodiments, the injected fluid is incompressible.

[0030] Robic File No.: 22186-0080

[0031] HQ File No.: 0886-PCT - 4 - In some embodiments, varying the fluid pressure and / or the fluid temperature includes controlling, by the control system, the mixing of two fluid lines having different temperatures, upstream of the housings.

[0032] In some embodiments, varying the fluid pressure includes controlling, by the control system, the flow rate at the inlet and / or outlet of the fluid in each of the housings.

[0033] In some embodiments, the applied fluid pressure varies between 10 PSI and 2500 PSI.

[0034] In some embodiments, the fluid temperature varies between -20°C and 80°C.

[0035] In some embodiments, the detected parameters include at least one of: a temperature inside the housings; a pressure in the housings; a current, a voltage or a power, and / or a derivative thereof, across the terminals of the housings.

[0036] In some embodiments, determining the pressure and temperature to be applied includes: analyzing, from the collected data, at least one characteristic among: conductivity (S / cm), critical current density (mA / cm2), coulombic efficiency (%), and capacity (mAh) of the cells; and identifying the pressure and temperature of the fluid in the housings that maximizes at least one of these characteristics.

[0037] In some embodiments, identifying the pressure and temperature maximizing at least one of said characteristics, the optimal pressure and optimal temperature from the collected data is carried out by algorithmic tools and / or artificial intelligence modules.

[0038] In some embodiments, at least two of the housings are composed of distinct materials, the method further comprising determining, based on the data collected, the material that minimizes the optimal pressure and / or brings the temperature to be applied to the fluid closer to a given ambient temperature, while maximizing the performance of the battery cell.

[0039] In some embodiments, the material is chosen from at least one of: steel, aluminum, carbon fiber, and magnesium.

[0040] In some embodiments, the pressure and temperature are varied and correspond to conditions required to comply with thermal shock tests.

[0041] Robic File No.: 22186-0080

[0042] HQ File No.: 0886-PCT - 5 - According to another aspect, a test bench is provided, enabling the determination, for different operating modes, of the respective pressures and temperatures to be applied to battery cells to maximize their performance under different operating modes. The test bench comprises: a set of hermetically sealed housings, each housing configured to accommodate a battery cell and including electrical connection terminals, a fluid inlet port and a fluid outlet port; a servo system for injecting and / or removing, through the fluid inlet and outlet ports of the housings, a fluid applying isostatic pressure to the battery cells and for varying the temperature and / or pressure of the fluid in each housing independently from one housing to another, according to different pressure and temperature profiles;a cycling device connected to the connection terminals of the housings to apply different cycling sequences to the cells, the cycling sequences corresponding to distinct operating modes; sensors to detect or read parameters indicative of, or affecting, battery performance; and one or more controllers to control the servo system and vary the pressure and / or temperature of the fluid, to control the cycling module by indicating the cycling sequences to be applied, to collect data derived from the detected parameters, and to determine, for each of the operating modes, a pressure and temperature to be applied to a given battery cell to maximize its performance.

[0043] In some embodiments, the test bench is configurable between: a servo mode in which the inlet fluidic port and / or the outlet fluidic port are connected to the servo system, allowing the isostatic pressure and / or temperature of the fluid to be regulated; and a passive mode in which the inlet fluidic port and the outlet fluidic port are closed, and in which the fluid pressure is isostatic and invariable for the duration of one or more of the cycling sequences.

[0044] In some embodiments, the cycling device is configured to apply a power draw or injection to each battery according to current and / or power profiles recorded in memory, and corresponding to previously collected real driving situations.

[0045] In some embodiments, the test bench includes two fluidic lines at different temperatures and a proportional distributor associated with each of the lines to vary the temperature of the fluid.

[0046] Robic File No.: 22186-0080

[0047] HQ File No.: 0886-PCT - 6 - In some embodiments, the servo system is configured to apply, independently in each of the housings, fluid pressures between 10 PSI and 2500 PSI.

[0048] In some embodiments, the control system is configured to apply fluid temperatures between -20°C and 80°C.

[0049] In some embodiments, the sensors include temperature sensors associated with control ports of each of the housings; pressure sensors associated with the fluidic inlet and / or outlet ports of the housings; and a current, voltage and / or power detector associated with the terminals of the housings.

[0050] In some embodiments, the housings each include a pressure relief valve connected to the fluid outlet port, the pressure relief valve allowing the fluid to be evacuated in case of overpressure.

[0051] In some embodiments, the housings each include a rupture disc, the rupture disc being configured to fracture at a predetermined pressure value and allowing excess gas and / or fluid to be vented to the outside in the event of thermal runaway.

[0052] In some embodiments, the controller(s) include one or more memory modules storing: the cycling sequences to be applied by the cycling device, the different pressure and temperature profiles to be applied by the control system for each operating mode to be tested, and the collected data derived from the detected parameters.

[0053] In certain embodiments, the controller(s) include algorithmic tools and / or artificial intelligence modules configured to identify the pressure and temperature maximizing, for each of the battery cells tested, at least one of the following: conductivity (S / cm), critical current density (mA / cm²). 2 ), the coulombic efficiency (%), and the capacity (mAh) of the cells, for each of the distinct operating modes.

[0054] In some embodiments, at least two of the housings are composed of distinct materials, chosen from at least one of: steel, aluminum, carbon fiber, and magnesium.

[0055] Robic File No.: 22186-0080

[0056] HQ File No.: 0886-PCT - 7 - BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 illustrates a test bench for testing housings, each including a battery cell, according to one possible embodiment.

[0058] Figure 2 illustrates a perspective view of an open case, without a battery cell, according to a first embodiment.

[0059] Figure 3 is an exploded and perspective view of an open case, with a battery cell, according to a second embodiment.

[0060] Figure 4 is a perspective view of the closed case of Figure 3.

[0061] Figure 5 is a top plan view of the housing in Figure 4.

[0062] Figure 6 is a cross-sectional view of the housing in Figure 5.

[0063] Figure 7 is a side view of the case in Figure 4.

[0064] Figure 8 is a perspective view of a box connected to a control interface of a servo system, according to one possible embodiment.

[0065] Figure 9 is a perspective view of a box connected to a control interface of a servo system, according to another embodiment.

[0066] Figure 10 shows a high-level functional diagram of a method for determining a pressure and temperature to be applied to a battery cell to maximize its performance in a given operating mode, according to one embodiment.

[0067] Figure 11 is a graph showing the conductivity curve of a battery cell having a given chemical composition, as a function of operating pressure, according to one embodiment.

[0068] Figure 12 is a graph showing the critical current density curve of the battery cell as a function of operating pressure, according to one embodiment.

[0069] Figure 13 is a graph showing the coulombic efficiency curves of the battery cell as a function of the number of cycles for different operating temperatures, according to one embodiment.

[0070] Robic File No.: 22186-0080

[0071] No. Dossier HQ: 0886-PCT - 8 - Figure 14 is a graph showing the coulombic efficiency curves of the battery cell as a function of the number of cycles for different operating pressures, according to one embodiment.

[0072] Figure 15 is a graph showing the battery cell resistance curve as a function of operating pressure, according to one embodiment.

[0073] Figure 16 is a graph showing the battery cell resistance curve as a function of operating temperature, according to one embodiment.

[0074] Figure 17 is a graph showing the curves of battery cell capacity as a function of the number of cycles for different operating pressures, according to one embodiment.

[0075] Figure 18 is a graph showing the curves of battery cell capacity as a function of the number of cycles for different operating temperatures, according to one embodiment.

[0076] Figure 19 is a graph showing the pressure control protocol curves as a function of the volume variation of the stack associated with the state of charge (SOC) over 4 cycles, according to one embodiment.

[0077] Figure 20 illustrates a servo system for a test bench, according to one possible embodiment.

[0078] DETAILED DESCRIPTION

[0079] In the description and figures that follow, similar components and / or functionalities are represented by the same reference numbers. To avoid cluttering the figures, some elements are not identified in all figures if they have already been shown in previous figures. The elements shown in the figures are not necessarily to scale, and the emphasis is rather on clearly illustrating the elements and structures of the various embodiments presented below.

[0080] Furthermore, although the described and illustrated embodiments include various components, and although some of these components have certain geometric configurations, it is understood that the number of components and their geometries may vary, and therefore should not be taken in a restrictive sense, nor should they be interpreted in a way that limits

[0081] Robic File No.: 22186-0080

[0082] HQ File No. 0886-PCT - 9 - the scope of this technology. It should be understood, as will also be apparent to the person skilled in the art, that other suitable components, as well as other suitable geometric configurations, may be used for this technology and corresponding parts thereof.

[0083] All technical and scientific terms and expressions used in this description have the same definitions as those generally understood by a person versed in the art of current technology. Definitions of certain terms and expressions used are nevertheless provided below.

[0084] The term "approximately" as used in this document means "around," "in the region of," "around," or any other expression with a similar meaning. For example, when the term "approximately" is used in connection with a numerical value, it could change that value above and / or below by a predetermined variation. In some examples, the predetermined variation is approximately 10% of the nominal value. This term can also take into account, for example, the experimental error of a measuring instrument, rounding, and / or statistical deviations. Where a range of values ​​is mentioned in this application, the lower and upper bounds of the range are, unless otherwise indicated, always included in the definition.

[0085] The device(s), method(s), and system(s) described herein, or at least elements thereof, can be implemented in computer programs running on programmable computers (e.g., a microcontroller), each comprising at least one processor, a data storage system including, for example, but not limited to, volatile and non-volatile memory elements, at least one input device, and at least one output device. In some examples, the programmable computer might be a programmable logic unit (PLC), a mainframe computer, a server and personal computer, a cloud computing system, a laptop computer, a personal data carrier (PDC), a cell phone, a smartphone, a wearable device, a tablet, a smart display device, a set-top box, or a virtual reality device.Each program is preferably implemented in a high-level programming language, procedural programming language, or object-oriented language to communicate with a computer system. However, programs may be implemented in assembly language or machine language. In all cases, the language may be compiled or interpreted. Each of these computer programs is preferably stored on a storage medium or a machine-readable device.

[0086] Robic File No.: 22186-0080

[0087] HQ File No.: 0886-PCT-10 - General or special programmable computer for configuring and operating the computer when the storage medium or device is read by the computer to perform the procedures described herein. In some embodiments, the systems may be integrated with an operating system running on the programmable computer.

[0088] Context

[0089] In this description, a battery cell is defined as a unitary electrical device capable of storing electrical energy and producing electrical current. In use, a battery cell can be used alone or in combination with other battery cells, preferably in a series arrangement, forming a battery module with different voltages to provide currents of varying intensities. The chemical compositions of battery cells can be solid-liquid or entirely solid, including various combinations, for example: Lithium-Cobalt Oxide, Lithium-Manganese Oxide, Lithium-Iron Phosphate, Nickel-Manganese-Cobalt, Nickel-Cobalt-Aluminum, Lithium-Titanate, and Lithium-Sulfur.

[0090] In particular, within the context of this description, battery cells can be used in various fields of application, such as, for example, but not limited to, electric vehicles or stationary energy storage.

[0091] In the case of electric vehicles, the method and test bench as described herein can be used to identify, for a battery cell having a specific size and chemical composition, the pressure and / or temperature parameters to be applied to the cell to achieve maximum performance from an electric vehicle battery module, composed of a set of these cells, particularly in extreme conditions where durability and reliability are crucial.

[0092] In the case of large-scale stationary energy storage, the use of an all-solid-state battery in a pressurized hydraulic tank could offer a sustainable and high-efficiency solution.

[0093] The lifespan of a battery cell can be affected by two types of use: at rest or in use. Calendar aging occurs when the battery is at rest or in storage. The parameters that influence this aging process are temperature and state of charge.

[0094] Robic File No.: 22186-0080

[0095] HQ File No.: 0886-PCT - 11 - When a battery is used for discharging or charging, this is known as cycle aging. This aging can be influenced by many parameters: temperature, changes in the state of charge, or current waveform. Cycle aging is therefore highly dependent on usage, i.e., the battery's operating mode.

[0096] Each battery cell may include a casing in which an anode, a cathode, and an electrolyte are encapsulated. The anode and cathode are spaced apart, with part of the anode and cathode in contact with the electrolyte, and the other part of the anode and cathode outside the casing to allow electrical contact.

[0097] Battery cells can come in various formats and structures, such as, but not limited to:

[0098] Pouch or sachet cell,

[0099] Cylindrical cells,

[0100] Prismatic cells.

[0101] As indicated below, battery cells can also have different chemical compositions and be made of different materials, for the anode, cathode, and electrolyte. Furthermore, the casing or housing in which the cells are encapsulated can also be made of different materials.

[0102] For example, and without limitation, battery cells can include various electrochemical couples for the electrolyte, such as Nickel / Cadmium (Ni-Cd), Nickel / Metal Hydride (Ni-MH), Nickel / Zinc (NiZn), Sodium / Nickel Chloride (Zebra), Lithium / Ion (Li-Ion), Lithium / Polymer (LiPo), Lithium / Phosphate (LiFePO4), or Lithium / Metal Polymer (LMP). These electrolytes are primarily in liquid form, but the liquid electrolyte can also be replaced by a solid material, which may be a plastic polymer, ceramic, compacted inorganic powders, or a mixture (also called an "all-solid-state battery"). Although this description refers to solid-state battery cells, it is understood that the method and test setup described herein also apply to liquid-state battery cells.

[0103] The anode can be composed of carbon, graphite, or lithium metal, while the cathode can be made of various materials used in combination, such as cobalt, manganese, aluminum, copper, nickel, lithium, or iron phosphate. The most common composition for the cathode is NMC technology, based on lithium, nickel, manganese, and cobalt. But it

[0104] Robic File No.: 22186-0080

[0105] HQ File No.: 0886-PCT - 12 - also exist NCA (lithium, nickel, cobalt and aluminium), LMO (Lithium, manganese), LNMO (Lithium, nickel, manganese), LCO (Lithium, cobalt), and LFP (lithium, iron phosphate) batteries.

[0106] Some of the batteries used in electrical systems such as electric vehicles must have pressure applied to the battery cell in order to optimize their performance and lifespan.

[0107] Indeed, increased pressure can improve the contact between the electrodes (anode and cathode) and the solid electrolyte. Good contact is essential to reduce interfacial resistance, which improves ionic conductivity and overall battery performance.

[0108] Applying pressure to the battery cell can also help densify the solid electrolyte, reducing the number of pores or voids that can impair ionic conduction. This leads to improved conductivity and greater energy efficiency of the battery cell.

[0109] Applying adequate pressure to the battery cell can also contribute to the battery's mechanical stability by preventing cracks or delamination between the electrolyte and electrode layers. This is crucial for battery longevity and for preventing short circuits.

[0110] In some all-solid-state batteries, particularly those using metallic lithium as the anode, pressure can also help inhibit the growth of dendrites (needle-like structures of lithium that can cause short circuits). By controlling dendrite growth, battery safety and lifespan are improved.

[0111] Finally, applying pressure to the battery cell can also influence the electrochemical performance of the battery by altering the crystalline structure of the solid electrolyte, which can affect ion mobility.

[0112] Therefore, to maximize battery cell performance in a given operating mode, it is important to apply optimal pressure and temperature values ​​to the battery cell. An operating mode for a cell or battery module (composed of several cells) can include sudden and / or constant power demands, sudden or prolonged braking, traffic conditions, and low (below -20°C) or high (above 30°C) temperatures.

[0113] It is possible to apply pressure to the battery cells, for example:

[0114] Robic File No.: 22186-0080

[0115] HQ File No.: 0886-PCT - 13 - 1) Isostatic pressure applied in a pressurized enclosure, the enclosure being filled with compressible gas;

[0116] 2) Mechanical pressure applied along an axis of the battery cell by a servo system (hydraulic cylinders) or at constant force (springs);

[0117] 3) A triaxial mechanical pressure applied mechanically along the 3 axes of the battery cell.

[0118] In the first example, uniform pressure is applied perpendicularly to all surfaces of the battery cell. It is also possible to regulate the pressure in real time with a servo system. If the pressure is not regulated, the (compressible) gas allows the battery to "breathe" during cycling, i.e., to vary in volume during charging (increasing in volume) and discharging (decreasing in volume). However, heat dissipation is limited if the battery cell heats up, and this solution does not allow for temperature variation. Finally, this solution allows for a limited maximum pressure with standard pneumatic equipment. This solution is also subject to a risk of explosion due to a high-pressure pneumatic tank, as well as the possibility of a tank leak.

[0119] In the second example, pressure is applied along a single axis of the battery cell, making it very difficult to guarantee uniformity of the applied pressure, or even perpendicularity of the force applied to the battery cell surface. However, it is possible to regulate the pressure in real time with a control unit equipped with a controllable actuator (electric, pneumatic, or hydraulic) that applies the force. In this solution, rapid temperature control is also not possible.

[0120] In the third example, pressure is applied along the three axes of the battery cell, but it remains very difficult to guarantee uniformity of the applied pressure, or even perpendicularity of the force applied to each surface of the battery cell. However, it is possible to regulate the pressure in real time with a control unit equipped with a controllable actuator (electric, pneumatic, hydraulic) that applies the force. In this solution, it is also not possible to rapidly change the temperature.

[0121] Existing devices mainly use mechanical or gaseous pressure methods which have limitations, particularly regarding the pressure (intensity and uniformity) to be applied.

[0122] The technology described here surpasses conventional methods used to apply pressure and / or temperature within the enclosure / case in several ways; it allows for high pressures, for example, over 500 MPa (for "warm isostatic" type presses).

[0123] Robic File No.: 22186-0080

[0124] HQ File No.: 0886-PCT - 14 - press" or "hot isostatic press"), safely. It then becomes possible, with the test bench and method described here, to apply high pressures and measure the battery cell response, which was not possible with existing solutions.

[0125] In particular, using an all-solid-state battery in a pressurized hydraulic reservoir, as described herein, is an innovative approach to optimizing the performance and durability of this type of battery. This technique relies on the use of hydraulic pressure to maintain optimal contact between the battery components, especially the electrodes (anode and cathode) and the solid electrolyte, and ensures a homogeneous distribution of force across the entire battery surface, which is essential for maintaining strong contact and minimizing internal resistance. This solution has the advantage of creating optimal and uniform contact.Indeed, hydraulic pressure ensures uniform contact between the different layers of the battery, thus improving conductivity and storage capacity by promoting better ionic transfer through the solid electrolyte and minimizing degradation due to the formation of cracks or voids.

[0126] Isostatic pressure also allows for the application of uniform and perpendicular pressure across all cell surfaces, helping, among other things, to prevent creep in more ductile materials that can lead to short circuits or crack propagation. For example, in liquid electrolyte cells, such as Li-ion cells, isostatic pressure allows for a more uniform distribution of the liquid electrolyte, while minimizing the risk of rupture of the cell encapsulation (bag). For cells with a lithium-metal anode, isostatic pressure minimizes the risk of material creep.

[0127] The incompressible nature of this pressure application method also makes it possible to completely prevent the cell's respiration or volume variation during operation, thus applying the principle of mechanical constriction, known to be beneficial under certain cell operating conditions. The test bench allows the use of an incompressible fluid (oil) or a compressible fluid (gas). Both types of fluid can generate isostatic pressure and offer advantages. That said, a hydraulic (incompressible) system, when controlled, can simulate the behavior of a compressible fluid.

[0128] This solution also helps to reduce structural defects: by minimizing the risks of formation of cracks or voids within the solid electrolyte and at the interfaces between the electrodes and the electrolyte, the battery life is extended.

[0129] Robic File No.: 22186-0080

[0130] HQ File No.: 0886-PCT - 15 - Finally, this solution increases battery cell safety, since the pressurized environment maintains the structural integrity of the battery cell, reducing the risk of short circuits and other failures. Furthermore, the optimal heat dissipation afforded by the immersion cooling approach allows for rapid temperature readjustment of the cells, notably preventing thermal runaway in the event of a failure.

[0131] The term "optimal pressure" as used in this document refers to the pressure that ensures uniform contact between the different layers of the battery cell, thereby improving the conductivity and storage capacity of the battery cell. Applying this pressure results in optimized cell operating capabilities, measured, for example, in coulombic efficiency or an increase in the permissible critical current density.

[0132] The term "optimal temperature" as used in this document refers to the temperature of the fluid inside the casing that minimizes the heating and cooling requirements of the battery cell while maintaining optimal pressure within the casing. Specifically, the optimal temperature falls within a safe operating range for the battery cells and remains as close as possible to ambient temperature to minimize the heating and cooling requirements of the battery cell.

[0133] The performance of a battery cell can be measured, among other things, by: its durability, expressed in cycle count, which corresponds to the number of complete charge and discharge cycles the battery can withstand before its initial performance degrades below values ​​typically used in industry, i.e., 70% to 80% of the cell's initial capacity. Lifespan, in turn, depends on the frequency of these cycles; its conductivity (A) or ionic conductivity, expressed in Siemens per centimeter (S / cm), which corresponds to the battery cell's ability to move ions across its electrodes. The higher the conductivity, the greater the quantity of ions passing through its electrodes. Ion mobility generally increases with temperature; and its critical current density (I), expressed in mA / cm². 2, corresponding to the current that the battery cell can withstand in cycling without cell failure due to dendrite growth or the creation of pores at the interfaces;

[0134] Robic File No.: 22186-0080

[0135] HQ File No.: 0886-PCT - 16 - Its coulombic efficiency (CE), also called faradaic efficiency or current efficiency, expressed as a percentage (%), describes the charging efficiency by which electrons are transferred in batteries. CE is the ratio of the total charge extracted from the battery to the total charge added to the battery over a complete cycle; its resistance (r), or internal resistance, expressed in ohms (Q), corresponds to the resistance offered to the flow of internal electric current between its electrodes. This depends on several factors such as battery type, chemical composition, age, temperature, state of charge, and application; and / or its capacity (C), expressed in milliampere-hours (mAh), indicates the amount of energy stored in the battery when charged and therefore the amount of energy that can be delivered.This recoverable capacity depends on the applied current density i, that is, the charging or discharging rate, called "C-rate" and defined by: i.

[0136] C — rate = — C

[0137] At a 10C rate, the battery will be discharged 100 times faster than at 0.1C. Thus, a 1000mAh battery will have to supply 1000mA for 1 hour at 1C, or 500mA for two hours at 0.5C.

[0138] The state of health (SoH) of a battery cell can also be determined. SoH is expressed as a percentage and is calculated by the ratio between the actual capacity and the initial capacity of the battery cell. When a battery cell reaches a SoH of 75%, it becomes critical. The actual capacity of a battery cell can be determined by its coulombic efficiency as a function of charging time.

[0139] The term "maximizing performance" as used in this document means applying the given pressure that promotes better ion transfer through the solid electrolyte of the battery cell and minimizes degradation due to crack or void formation, while maintaining the integrity of the materials (anode, cathode, electrolytes). In other words, "maximizing the performance" of a battery cell can mean, among other things, minimizing resistance, maximizing coulombic efficiency, and maximizing the critical current of the battery cell without compromising its state of health (SoH).

[0140] For example, "maximizing performance" could mean reducing the battery cell charging time without impacting the battery's state of health (SoH), i.e., without damaging the battery cell. In particular, the method and test bench as described herein

[0141] Robic File No.: 22186-0080

[0142] No. File HQ: 0886-PCT - 17 - request allow to determine a pressure and / or temperature of the fluid in the case which allow to stress the battery cell more in current demand without there being a consequence on the battery and without degrading the capacity of the battery cell.

[0143] In another embodiment, "maximizing performance" could also mean operating the battery cell at temperatures outside their nominal battery cell operating range, without having to heat or cool the battery cell and without causing damage to the battery cell.

[0144] Alternatively, "maximizing performance" could mean minimizing the calendar aging of the battery cell, with calendar aging causing damage to the battery cell during storage, subjected to temperature variations.

[0145] The optimal pressure and temperature can vary depending on several battery cell parameters, for example, but not limited to:

[0146] The materials used for the anode, cathode, and electrolyte,

[0147] The structure of the cell,

[0148] The type of stress (loading or unloading),

[0149] The context of use (application, ambient temperature);

[0150] The materials of the casing or housing encapsulating the cells or a cell module.

[0151] The proposed method and test bench allow for the systematic determination, for a combination of the cell characteristics listed below (chemical composition, size, housing material, external or ambient temperature), of the pressure-temperature pair to be applied to the fluid to maximize cell performance.

[0152] Test bench and associated method

[0153] The technology described here relates to a test bench for experimentally determining a pressure and / or temperature, or a series of pressures and temperatures (which may correspond to a pressure and temperature profile), to be applied to a battery cell to maximize its performance in a given operating mode, prior to its use. The proposed technology can be used experimentally, and the test bench aims to qualify different battery cell technologies (e.g., composition combinations).

[0154] Robic File No.: 22186-0080

[0155] HQ File No.: 0886-PCT - 18 - chemical, size, material for housing), intended to be integrated into an end system such as an electric vehicle.

[0156] The test bench described here allows for the highly accurate determination of one or more pressure and / or temperature values ​​to be applied to a battery cell. The method and test bench can be adapted to any type of battery cell, for different operating modes, and can be implemented on multiple battery cells in parallel.

[0157] Referring to Figure 1, it shows a test bench 10 for determining, under different operating conditions, a pressure and temperature profile to be applied to a battery cell to maximize its performance, according to one embodiment. The test bench 10 comprises a set of hermetically sealed housings 20, each housing 20 configured to accommodate a battery cell and including electrical connection terminals, a fluid inlet port, and a fluid outlet port (visible in Figures 2, 3, or 6). The test bench also includes a control system 50 for injecting and / or removing, through the fluid inlet and outlet ports of the housings, a fluid applying isostatic pressure to the battery cells.The control system 50 also allows the temperature and / or fluid pressure in each cell to be varied independently, according to different pressure and temperature profiles. The test bench also includes a cycling device 70 connected to the cell terminals to apply different cycling sequences to the cells, each sequence corresponding to a distinct operating mode. The test bench includes sensors to detect or read parameters indicative of battery performance.The test bench also includes one or more 90 controllers to control the servo system and vary the pressure and / or temperature of the fluid, to control the cycling module by indicating the cycling sequences to be applied, to collect data derived from the detected parameters, and to determine, for each of the operating modes, the pressure and temperature profile to be applied to a given battery cell to maximize its performance.

[0158] Housing

[0159] Figures 2 to 7 illustrate several configurations of the housing 20. Each housing 20 comprises a lid 21a and a base 21b, the lid 21a being complementary to the base 21b and substantially stackable on the base 21b. The lid 21a and the base 21b are substantially recessed on the facing surfaces, so as to create a cavity or chamber 23 between the lid 21a and the base 21b when they are stacked or nested together.

[0160] Robic File No.: 22186-0080

[0161] HQ File No.: 0886-PCT - 19 - In one embodiment, the housing 20 may include a sealing gasket 23a to ensure insulation of the cavity 23 once the housing 20 is sealed.

[0162] Each housing 20 is designed to receive a battery cell 40 in its cavity 23. When the battery cell 40 is positioned in the cavity 23 of the housing 20, the cathode 44 and the anode 42 of the battery cell 40 are electrically connected to a positive electrical connection terminal 25 and a negative electrical connection terminal 26 of the housing 20, respectively. The positive electrical connection terminal 25 and the negative electrical connection terminal 26 of the housing 20 allow an (electrical) connection between the battery cell 40 and the outside of the housing 20. The terminals of the individual housings are connected to the cycling device via electrical connections, the cycling device being able to perform power surges or surges (charge / discharge) for each cell.In the embodiments shown in Figures 2 to 7, the casing 20 is substantially rectangular, and the battery cell 40 is also substantially rectangular, but the casing can be adapted to all cell shapes and sizes, including cylindrical cells. In one possible embodiment, the test bench 10 can include different types of casings, each adapted to receive a battery of a given chemical composition and size. In this configuration, the proposed test bench allows an organization developing different types of batteries to test the pressures and temperatures to be applied to the fluid contained in the casing for these different technologies under development, and for different operating modes.

[0163] In the embodiment shown in Figure 2, the positive electrical connection terminal 25 and the negative electrical connection terminal 26 of the housing 20 are located on the same side of the housing 20, the housing 20 being intended to receive a battery cell 40 whose anode 42 and cathode 44 are also on the same side of the battery cell 40.

[0164] In the embodiment shown in figures 3 to 7, the positive electrical connection terminal 25' and the negative electrical connection terminal 26' of the housing 20' are located on opposite sides of the housing 20', the housing 20' being intended to receive a battery cell 40' whose anode 42' and cathode 44' are also on opposite sides of the battery cell 40'.

[0165] Once the battery cell 40 is placed in the cavity 23 of the housing 20 (FIG. 3), the housing 20 is then closed by fitting the cover 21a of the housing 20 onto the base 21b of the housing 20 (FIG. 4). Fastening elements 27 secure the cover 21a to the base 21b, ensuring a hermetic seal of the housing 20. A sealing gasket is then slightly

[0166] Robic File No.: 22186-0080

[0167] HQ File No.: 0886-PCT - 20 - compressed between the cover 21a and the base 21b, thus ensuring the airtightness of the housing 20. The fastening elements 27 are configured to withstand very high pressures, for example pressures exceeding 1500 psi (10 MPa).

[0168] The housing 20 may also include an inlet fluidic port 22 and an outlet fluidic port 24, enabling a fluidic connection between the exterior and interior of the housing 20. In particular, a portion of the housing material 20 may be hollowed out to create a tunnel between the cavity and the fluidic ports. With reference to Figure 2, a first tunnel 22a enables a fluidic connection between the cavity 23 and the inlet fluidic port 22, and a second tunnel 24a enables a fluidic connection between the cavity 23 and the outlet fluidic port 24. The inlet fluidic port 22 and the outlet fluidic port 24 may be closed with a hermetic plug, or they may be open and connectable to a servo system 50, as described below.

[0169] In one embodiment, the housing 20 may also include a control connector 28 allowing for another fluid connection between the outside and inside of the housing 20. Similar to the inlet fluid ports 22 and outlet fluid ports 24, a portion of the housing material 20 may be hollowed out to create a third tunnel 28a between the cavity 23 and the control connector 28. Thus, the control connector allows for a fluid connection with the cavity 23. The control connector 28 also allows a temperature sensor, such as a thermocouple 39, to be connected to the housing 20, and thus to measure the temperature inside the cavity 23. When no thermocouple 39 is connected to the control connector 28, the control connector 28 is hermetically sealed to prevent any fluid leakage from the cavity.

[0170] The housing 20 can be made of a material with varying degrees of deformability, including but not limited to steel, aluminum, magnesium, carbon fiber, or any other suitable material or a combination thereof. The elasticity (or deformability) of materials is measured by Young's modulus. This Young's modulus is an intrinsic property of the material used and is a constant that relates the tensile (or compressive) stress and the deformation of an isotropic elastic material. It therefore measures the material's stiffness with respect to a (small) uniaxial deformation. For example, steel has a high Young's modulus (approximately 200 GPa), while aluminum (Al) and magnesium (Mg) have low Young's moduli (approximately 69 GPa for Al and 45 GPa for Mg). This means that the stress required to deform steel will be much greater than the stress required to deform aluminum or magnesium.Thus, according to one possible embodiment, by including in the test bench housings made of different materials, the test bench makes it possible to test the performance.

[0171] Robic File No.: 22186-0080

[0172] HQ File No. 0886-PCT - 21 - of a given cell under different encapsulation conditions, allowing identification of the battery cell housing manufacturing process that, for a given fluid pressure, achieves the best possible coulombic efficiency. When used in passive mode (hydraulic inlet and outlet ports sealed), housings made of different materials will exhibit different pressure-temperature curves. Therefore, for the same temperature rise, different pressure fluctuations will be observed for the housings, depending on the material chosen for their manufacture, when used in passive and temperature-controlled mode.

[0173] The heat dissipation of the material used for the 20 case can also be considered. For example, aluminum is a material with a significantly higher heat dissipation rate than steel.

[0174] The choice of material used for the casing can therefore depend on the type of battery cell to be tested, the target operating pressure (deformation versus sealing) or the desired rigidity (deformation under pressure stress), the desired thermal conductivity, as well as the conditions of use of the battery cell, as will be detailed later.

[0175] As illustrated in Figure 6, once the battery cell 40 is placed in the housing 20 and the housing 20 is hermetically sealed, the cavity space not occupied by the battery cell 40 can be filled with a fluid 60. In the described embodiment, the fluid 60 is an oil, but other fluids such as gases could be used. Oil has the advantage of lubricating the hydraulic pump, allows for better heat dissipation, and is easier to modulate in temperature. Preferably, the chosen fluid is incompressible, meaning that its degree of compressibility is negligible for the applied pressure and temperature ranges. Examples of incompressible fluids include mineral oils and / or silicone oils. Mineral oils can be paraffin-based and / or petroleum-based, and may include alkanes, cycloalkanes, and / or esters.

[0176] In one embodiment, the fluid 60 can be initially injected into the cavity 23 of the housing 20 via the fluid inlet port 22, for example by means of the servo system. In another embodiment, the housing could be supplied already filled with fluid 60.

[0177] In one embodiment (not shown), the housings 20 may also include at least one heating and / or cooling module, allowing the temperature of the fluid 60 contained in the cavity 23 of the housing 20 to be varied. For example, the cover 21a and / or the base 21b of the housing 20 may include a Peltier effect module. According to another embodiment,

[0178] Robic File No.: 22186-0080

[0179] HQ File No. 0886-PCT - 22 - as shown in Figure 20 and described in more detail, the test bench may include two fluid lines at different temperatures, including, for example, a proportional distributor associated with each line to vary the fluid temperature. A "mixing" type system thus allows control of the flow rate of the two lines before they are combined into a single fluid line for which the fluid temperature is controlled.

[0180] In one embodiment, as illustrated in Figure 8, each casing 20 may include a rupture disc 29. The rupture disc, strategically located on a central portion and on an exposed surface of the casing 20, is in fluidic communication with the cavity 23 of the casing. The rupture disc 29 is a pressure-tight safety device, configured to fracture at a predetermined pressure value, i.e., when the pressure of the fluid 60 inside the cavity 23 reaches abnormal values ​​(i.e., above a pressure threshold) and outside normal operating ranges, which could cause damage to the battery cell 40 and / or a user. In particular, in the event of thermal runaway of the battery cell 40, the battery cell overheats, causing a considerable increase in the temperature and pressure of the fluid 60 inside the cavity 23.Furthermore, explosive gases can be generated and must be vented. In such circumstances, the rupture disc 29 fractures to allow the gases and excess fluid to escape, thus preventing an explosion of the housing 20. The rupture disc provides protection against overpressure and, once fractured, allows large quantities of fluid and gas to escape. The rupture disc 29 is a single-use device, meaning it cannot be resealed once opened. In this case, the rupture disc 29 must be completely replaced if it fractures. This possible housing configuration allows for the safe application of pressures ranging from 0 to 12 MPa during different cycling sequences.The rupture disc can be selected according to the pressure ranges to be tested on the battery cells, so as to rupture beyond a pressure threshold exceeding the pressure ranges under test, ensuring the safety of operators or technicians.

[0181] Servo control interface

[0182] In one embodiment, and with reference to Figures 8 and 9, the test bench 10 may include a servo control interface 30. This servo control interface 30 allows the connection of the housing 20 to the servo system 50. In particular, the servo control interface 30 may include a pressure gauge 33

[0183] Robic File No.: 22186-0080

[0184] HQ File No.: 0886-PCT - 23 - connected to the hydraulic inlet port 22 of the housing 20. This pressure gauge allows continuous measurement of the pressure of the fluid 60 contained in the housing. The pressure gauge 33 may also include a connection 33a, allowing the gauge to be powered and the reading value to be acquired. In one embodiment, the connection 33a of the pressure gauge 33 can be connected to the controller 90.

[0185] The servo control interface 30 may also include a pressure relief valve 31, connected to the hydraulic output port 24 of the housing 20. This pressure relief valve 31 allows excess fluid to be safely discharged in case of overpressure.

[0186] The servo control interface 30 can also include an inlet control valve 32 and an outlet control valve 34. These inlet / outlet control valves 32, 34 are each positionable between a closed position and an open position, resulting in three configurations of the servo control interface 30: inlet control valve 32 open and outlet control valve 34 open: the hydraulic inlet and outlet ports 22, 24 are in fluidic connection with the servo system 50 for a loop circulation of the fluid.This is a pressure- and temperature-controlled mode, since the control system 50 can vary the fluid pressure and temperature; with the inlet control valve 32 open and the outlet control valve 34 closed: only the hydraulic inlet port 22 is in fluidic connection with the control system 50, while the hydraulic outlet port 24 is closed. This is a pressure-controlled mode, since the control system 50 can vary the fluid pressure by injecting or withdrawing additional fluid from the housing 20; with the inlet control valve 32 closed and the outlet control valve 34 closed: the hydraulic inlet and outlet ports 22 and 24 are disconnected and isolated from the control system. This is a passive mode, in which the fluid pressure and temperature are fixed.

[0187] It should be noted that a fourth configuration of the test bench 10 can be considered, in which the inlet control valve 32 and the outlet control valve 34 are closed, the housing 20 is placed in an oven and / or the housing 20 is equipped with at least one heating and / or cooling module, in order to vary the temperature of the fluid contained in the housing 20. This is a temperature-controlled mode, which indirectly allows the pressure value of the housing to be controlled. Indeed, due to the coefficient of thermal expansion of the fluid and the constant volume of the

[0188] Robic File No.: 22186-0080

[0189] HQ File No.: 0886-PCT - 24 - housing, a rise in fluid temperature will cause a rise in pressure within the housing. The test bench 10 can therefore be configured between a servo-controlled mode in which the inlet and / or outlet fluid ports of each housing are connected to the servo system, allowing regulation of the isostatic pressure and / or fluid temperature, and a passive mode in which the inlet and outlet fluid ports are closed, and in which the fluid pressure is isostatic and constant for the duration of one or more cycling sequences. In one possible embodiment, the housings of the test bench can be configured in servo-controlled or non-servo-controlled mode, independently of one housing to another. Thus, it may be possible to cycle in parallel (i.e.simultaneously) several cells of the same chemical composition, in different modes, for example, one housing controlled by pressure and temperature, another housing controlled by pressure only, and another housing in non-controlled mode, and to monitor the effect of these conditions on the cells, to determine the pressure and / or temperature profile to apply for a given operating condition (e.g. rapid charging of the cells).

[0190] The servo control interface 30 may also include input and output connection ports 36, 38, allowing connection to the servo system 50. Once connected to the servo system 50, the incoming fluid 62 can enter the housing 20, and the outgoing fluid 64 can be discharged from the housing 20.

[0191] To increase the temperature of the fluid inside the casing 20, the servo system 50 injects an incoming fluid 62 of a temperature higher than the current temperature of the fluid in the casing, which circulates inside the casing, the cooler outgoing fluid 64 being pumped out by the servo system 50.

[0192] Conversely, to lower the temperature of the fluid inside the casing 20, the servo system 50 injects an incoming fluid 62 with a temperature lower than the current temperature of the fluid in the casing, which circulates inside the casing, the hotter outgoing fluid 64 being pumped out by the servo system 50.

[0193] Control system

[0194] In one embodiment, and with reference to Figure 1, the test bench 10 may include a control system 50. In the illustrated case, the control system 50 is a hydraulic control system for controlling the flow of a fluid such as oil, but it is understood that other control systems may be used, depending on the fluid.

[0195] Robic File No.: 22186-0080

[0196] HQ File No.: 0886-PCT - 25 - used. In particular, the servo system 50 may include a hydraulic pump for injecting and / or pumping fluid. The servo system 50 may also include a means of heating the fluid. In the case where the fluid used is a gas, the servo system 50 may include a compressor to vary its pressure.

[0197] This servo system 50 is controlled by control signals from the controller 90, via a controller-servo system connection 95. The controller can be a programmable logic controller (PLC) or a dedicated server, as an example only. For example, the controller 90 can transmit a pressure and / or temperature setpoint for the fluid, independently for each housing. Thus, the servo system 50 can, for each housing: inject, through at least one servo input / output port 52, the quantity of fluid necessary to reach a setpoint pressure, if the setpoint pressure is greater than the current pressure in the housing 20; or discharge, through at least one servo input / output port 52, the quantity of fluid necessary to reach the setpoint pressure, if the setpoint pressure is less than the current pressure in the housing 20.inject through at least one servo input / output connection port 52 a quantity of hot fluid necessary to reach the setpoint temperature, if the setpoint temperature is higher than the current temperature in the housing 20, inject through at least one servo input / output connection port 52 a quantity of cold fluid necessary to reach the setpoint temperature, if the setpoint temperature is lower than the current temperature in the housing 20.

[0198] In one embodiment, the servo system 50 includes a plurality of servo input / output connection ports 52, allowing control of the servo system of several enclosures 20, 20', 20" in parallel, and in a synchronous or asynchronous manner (i.e., different pressure and / or temperature setpoints for each enclosure 20, 20', 20").

[0199] Figure 20 shows a servo system 500 that can be used in a test bench of the invention, according to another possible embodiment. In this example, the test bench comprises four housings 540a, 540b, 540c, and 540d, but a different number of housings could be used. The servo system 500 includes a main pump 552 and a main fluid reservoir 550. In this example, the fluid is an incompressible mineral oil. The system includes a fluid inlet line 506 splitting into two

[0200] Robic File No.: 22186-0080

[0201] HQ File No.: 0886-PCT - 26 - Independent fluid lines 510 and 514, one heated and the other cooled, which can be controlled by a temperature management control system 520. The two fluid lines are subjected to different temperatures and are mixed in a controlled manner according to a given temperature profile. A pressure management control system 530 allows independent control of the fluid pressure in each housing. In this diagram, the same part numbers are used for the same types of devices. At the inlet of the hydraulic circuit, the pump 552 injects the fluid from the reservoir 550. A pressure relief valve 554 and a solenoid valve 556, arranged in parallel between the inlet fluid line 506 and the return fluid line 508, allow control of the flow and / or shut-off of the fluid in the circuit.

[0202] The fluid inlet line 506 is split into two separate fluid lines, 510 and 514. The first fluid line, 510, is heated by an oven 558, and the second fluid line, 514, is cooled by a freezer 560. In this example, the oven 558 heats the secondary fluid reservoir to 80 degrees Celsius, while the freezer cools the second secondary fluid reservoir to -20 degrees Celsius. Other temperatures are possible. The temperature of each fluid line is detected and monitored by a temperature sensor and transmitted by a temperature transmitter to the temperature management system 520, which can be implemented in the controller 90 (shown in Figure 1). The fluid lines 510 and 514, each having different temperatures, are mixed in a controlled manner via their respective proportional distributors 562.The temperature of the mixed fluid is transmitted, via a temperature transmitter 564, to the temperature control system 520. The temperature-controlled fluid is then injected into each of the four housings via separate fluid lines. In this example, the fluid temperature is the same for all housings, but it is possible for the fluid temperature for each housing to be adjusted independently.

[0203] The fluid pressure at the inlet of each housing is controllable via nitrogen pressure accumulators 566. Other control methods are possible. Pressure transmitters 568, connected to pressure sensors located at the inlet of each housing, periodically and / or continuously transmit the pressure measured at the inlet of each housing 540a-540d. At the inlet of each housing, a manual shut-off valve 570 allows the fluid inlet to be blocked, if necessary. Each of the housings 540a-540d includes a temperature sensor to measure the temperature of the fluid inside the housing. In this example, the temperature sensors are thermocouples 572. On / off poppet valves allow

[0204] Robic File No.: 22186-0080

[0205] HQ File No.: 0886-PCT - 27 - also to control the fluid outlet of the housings, located in series with controlled pressure regulating valves 574.

[0206] The temperature control system 520 and pressure control system 530 can be implemented via one or more controllers. A programmable logic controller (PLC) is preferably used. The controller, an example of which is shown in Figure 1, controls the various devices of the servo system to vary the pressure and / or temperature of the fluid according to temperature and / or pressure profiles. The controller can thus vary the fluid temperature from -20°C to +80°C, and vary the pressure from 10 PSI to 2500 PSI. This controller can also collect data derived from the detected parameters, including at least the temperature and pressure of the fluid in the housings. The servo system 500 can operate in a closed loop, with the fluid exiting the housings being returned, via the return fluid line 508, to the reservoir 500.

[0207] Cycling device

[0208] In one embodiment, and with reference to Figure 1, the test bench 10 includes a cycling device 70.

[0209] The 70 cycle unit can perform several cycling sequences, including the application or application of current (or power) corresponding to battery cell charging and discharging. The 70 cycle unit also allows for testing, among other things, lifespan, capacity, performance, charge / discharge, charge retention, recovery capacity, charge / discharge efficiency, deep discharge, constant voltage discharge, and susceptibility to overcharge and over-discharge. The tests or cycling sequences can be performed at different fluid temperatures to characterize the internal resistance of the cell and to replicate battery cell operating conditions.

[0210] The cycling device 70 is connected to the housing 20 by at least one cycling device-housing connection 74 and is capable of acquiring in real time the voltage, current, capacity and energy of the battery cells 40. In particular, each cycling device-housing connection 74 allows a connection between the connection port 72 of the cycling device 70 and the positive and negative electrical connection terminals 25, 26 of the housing 20.

[0211] Robic File No.: 22186-0080

[0212] HQ File No.: 0886-PCT - 28 - In the illustrated case, the cycling device 70 may include a plurality of cycling connection ports 72, each cycling connection port 72, 72', 72" being connected to the positive electrical connection terminals 25 and negative electrical connection terminals 26 of each housing 20, 20', 20".

[0213] The cycling device 70 can be controlled by control signals from the controller 90, by means of a controller-cycling device connection 98.

[0214] Controller

[0215] In one embodiment, and with reference to Figure 1, the test bench 10 may include a controller 90. The controller 90 communicates with the cycling device 70 via the controller-cycling device connection 98, and with the control system 50 via a controller-control system connection 95. The controller 90 sends cycling commands to the cycling device 70, as well as commands for regulating fluid pressure and / or temperature to the control system 50. The controller 90 also receives data from the cycling device 70 and from the control system 50. For example, each battery cell can transmit battery cell-specific parameters to the cycling device 70 via the cycling device-housing connection 74, such as the battery cell voltage level. or the current flowing through the battery cell.These parameters can then be transmitted to the controller 90 via the controller-cycling device connection 98. In one embodiment, the controller 90 may include software that processes the battery cell parameters received from the cycling device 70 to determine, for example, the SoH and SoC of the battery cell. This software may be commercial software, such as, but not limited to, Batalyse software. Figure 1 shows a single control device 90, but in other embodiments, the control, coordination, and data collection functions may be distributed among several devices, located locally, near the test bench, or remotely, such as on cloud servers.Thus, one or more controllers may include one or more memory modules storing: the cycling sequences to be applied by the cycling device, the different pressure and temperature profiles to be applied by the control system for each operating mode to be tested, and the collected data derived from the detected parameters.

[0216] According to one possible embodiment, an organization wishing to determine the pressure and / or temperature of the fluid in the cell casing or housing can use different historical operating conditions of electric vehicles to establish the cycling sequences to be performed, i.e., so that the different cycling sequences represent operating conditions

[0217] Robic File No.: 22186-0080

[0218] HQ File No.: 0886-PCT - 29 - actual battery performance. Thus, the proposed test bench and method can establish fluid pressure and / or temperature for various operating modes, representative of real-world operating conditions, for example, continuous power demand. For a specific operating mode, the selected pressure and temperature will correspond to those that maximize coulombic efficiency, minimize cell degradation, reduce charging time, etc.For a given operating mode, such as intermittent braking or reduced power demand (representing driving conditions in traffic), the pressure / temperature applied to the fluid (and therefore to the battery cell) will be different and will be determined to maximize cell performance (coulombic efficiency, charging capacity / speed, durability) for the cycling sequences representing that operating mode. Given the high complexity of the data to be analyzed, advanced numerical analysis tools (combinatorial, stochastic optimization, etc.) and / or optimization algorithms can be used. With algorithmic analysis tools, it is possible to prioritize certain gains over others.For example, depending on the cell application, the pressure and temperature to be applied can be selected to prioritize coulombic efficiency over discharge rate for a given operating condition, such as a sudden power demand. Furthermore, to determine the pressure / temperature to apply to a cell with a new chemical composition, predictive AI (artificial intelligence) models can be used to determine the cycling sequences to apply and the pressure / temperature ranges to test in order to converge more quickly to the optimal pressures and / or temperatures for the fluid.

[0219] The controller(s) may therefore include algorithmic tools and / or artificial intelligence modules configured to identify the pressure and temperature profile that maximizes, for each of the battery cells tested, at least one of the following: conductivity (S / cm), critical current density (mA / cm²), coulombic efficiency (%), and cell capacity (mAh), for each of the distinct operating modes. Artificial intelligence models and / or algorithms can process cycling data for a given battery during extended testing, analyze it, and determine the optimal operating pressure and temperature values ​​as a result of these tests.

[0220] In one possible embodiment, during prolonged testing, these algorithms can slightly vary the pressure and temperature values ​​from one cycle to the next, observing the effect

[0221] Robic File No.: 22186-0080

[0222] No. File HQ: 0886-PCT - 30 - immediate (during a cycle), even slight, of these variations on performance, and converge more quickly to optimal values, and this during testing.

[0223] Within the algorithms, performance indicators, as described in the context section, can be prioritized to achieve specific performance levels for a given use case. For example, the test bench can be used to design a battery capable of ultra-fast charging in particularly hot climates for a high-performance vehicle application (luxury car / extreme performance). The algorithms can control the servo system to apply different temperature and pressure values ​​to the fluid under different cycling sequences, converging towards pressure and temperature values ​​that favor these specific indicators. AI algorithms can also be trained to determine the optimal time to perform a self-healing protocol.All these applications are possible thanks to the performance of the method and the system, namely the ability to vary pressure and temperature values ​​quickly and precisely.

[0224] In one embodiment, the controller 90 can also receive readings from the pressure gauges 33 of each housing 20, 20', 20" in order to continuously monitor the pressure inside the housings 20, 20', 20" by means of at least one controller-housing connection 96, 96', 96".

[0225] In one embodiment, the controller 90 can also receive readings from the thermocouples 39, 39', 39" of each housing 20, 20', 20" in order to continuously control the temperature inside the housings 20, 20', 20" by means of at least one controller-housing connection 96, 96', 96".

[0226] In one embodiment, the controller 90 can also be connected via a controller-HMI connection 94 to a human-machine interface (HMI) 92, such as a computer, tablet, or smartphone. The HMI allows the operator to remotely monitor the results of the test bench 10, for example, if the test bench is located in a secure, explosion-proof chamber.

[0227] In one embodiment, software is embedded in the controller 90 to generate the cycling sequences of the plurality of boxes 20, 20', 20" under test.

[0228] In one embodiment, the controller 90 includes one or more memory modules containing the different pressure and temperature profiles to be applied by the control system 50 for each operating mode to be tested.

[0229] Robic File No.: 22186-0080

[0230] HQ File No.: 0886-PCT - 31 - In one embodiment, the 20, 20', 20" enclosure(s) could be placed in an oven to replicate an outside temperature or outside temperature range.

[0231] It is understood that the embodiments described in connection with Figures 1 to 9 are only possible embodiments, among others. Thus, the test bench could include a different number of test boxes. The controller could include different sub-modules.

[0232] Method

[0233] Figure 10 presents a functional diagram including the steps of method 100 for operating a battery cell test bench to determine respective pressures and temperatures to be applied to the fluid circulating in the cases, according to different modes of operation.

[0234] The first step 110 consists of arranging the battery cells 40 in hermetically sealed cases 20. Each case is sized and configured to house one of the battery cells and includes electrical connection terminals 25, 26, a fluid inlet port 22 and a fluid outlet port 24. In one embodiment, the cases are pre-filled with a fluid 60, preferably incompressible.

[0235] The second step 120 consists of injecting fluid via the servo system to apply isostatic pressure to the battery cells 40. The fluid 60 is kept under pressure, thus applying uniform pressure to the battery cells in all directions simultaneously—on the top, bottom, and sides of the battery cells. Nitrogen-pressurized accumulators can be used upstream of the casings to apply the desired pressure. These accumulators are controlled by a controller 90, such as a Programmable Logic Controller (PLC), as shown in Figure 1. Solenoid valves located upstream and downstream of the casings allow or block the flow of fluid into the casing cavities. Pressure-controlled regulating valves located downstream of the casings also allow control of the fluid pressure within each casing.

[0236] The third step, 130, involves initiating cycling sequences for the battery cells 40. The cycling device, which includes electrical connections to each of the terminal pairs (negative and positive) of the casings, applies the cycling sequences to the cells. The cycling sequences correspond to different possible operating modes for the battery cells. The cycling sequences may include series of charging and discharging the cells, during which the cell current is controlled.

[0237] Robic File No.: 22186-0080

[0238] HQ File No.: 0886-PCT - 32 - For example, the discharge or charge rate of a cell can be measured against its maximum capacity in Ampere-hours (Ah). A rate of 1C indicates that the cell will fully discharge in one hour, while a rate of 0.5C (or C / 2) indicates that a cell will fully discharge in two hours. The currents flowing through each cell in the enclosures and the times required to reach predetermined cutoff voltages can be measured continuously or periodically by the cycling device. The product of the current and the time provides the discharge capacity in Ampere-hours (Ah) or Watt-hours (Wh). Cycling sequences can also include measuring the voltage across the cells under different charging conditions, measuring the cells' capacity to store energy, and / or measuring the cells' internal resistance.

[0239] During cycling, the apparatus 70 applies conditions representative of different operating modes 140. These different operating modes may include, for example, rapid charging at a fixed rate or a variable rate; pulsed charging and discharging; no charging or recharging, corresponding to a cell at rest or in storage, at very cold or very hot temperatures; and charging at very cold or very hot temperatures. One of the advantages of this test bench and its operating method is that each of the housings (and the cells they contain, respectively) can be subjected to specific cycling sequences, with temperature and / or pressure conditions that can be applied to each housing independently. This allows for much faster convergence to the optimal pressure and / or temperature conditions to be applied to the cells, according to a given operating mode.Thus, it is possible to apply a continuous power feedback (current injection) to one of the test bench units, corresponding to battery charging. Meanwhile, another operating mode can be applied to another of the test bench units, including, for example, alternating power demand and power feedback (corresponding to accelerations followed by braking during driving); no power demand or feedback (corresponding to a battery at rest or in storage); or a reduced power demand (representing a low-speed driving condition). Each unit can be subjected to a specific cycling sequence, varying the temperature and / or pressure of the fluid during this sequence. Again, in one possible embodiment, the temperature and / or pressure can be varied and controlled by the servo system independently of each unit.In one embodiment, it is possible to maintain a constant fluid temperature in the housings by varying only the pressure. In another embodiment, it is possible to maintain...

[0240] Robic File No.: 22186-0080

[0241] HQ File No.: 0886-PCT - 33 - maintains constant fluid pressure in the housings, varying only the temperature. Preferably, both parameters, temperature and pressure, are varied for a given cycling sequence.

[0242] The fluid pressure can be varied by injecting additional fluid into the housing 20 via the inlet fluid port 22 and / or by evacuating excess fluid from the housing 20 via the outlet fluid port 24 by means of the servo system 50. The temperature of the fluid in each of the housings can be controlled by mixing valves located upstream of the housings, using for example proportional distributors on two fluid lines having different temperatures.

[0243] In one embodiment, the applied fluid pressure can vary between 10 PSI and 2500 PSI, or between 100 PSI and 900 PSI, and preferably between 200 PSI and 400 PSI. The applied fluid temperature can vary between -20°C and 80°C. For example, a freezer can maintain one of the fluid lines at -20°C and an oven can maintain the other fluid line at 80°C. By mixing the two fluid lines in a controlled manner, the temperature of the fluid injected into the housings can vary between -20°C and 80°C.

[0244] During cycling, battery cell performance is monitored by collecting data on its operation under conditions representative of the operating mode. Various parameters can be detected by sensors attached to the battery cases. For example, the temperature inside each case can be detected by temperature sensors, such as thermocouples, connected to control ports on the cases. The pressure inside each case can also be monitored by pressure sensors. Current, voltage, resistance, or any measurements derived from these parameters can be monitored by appropriate sensors, including, for example, ohmmeters, ammeters, voltmeters, current transformers, etc. These measurements can be taken via the cycling device. The data is collected by one or more controllers, such as PLCs or other computers and / or servers.

[0245] In particular, the data collected during cycling tests may include current consumed (discharge), current injected (charge), ambient temperature, battery state of charge (SOC), battery state of health (SOH), conductivity (S / cm), and critical current density (mA / cm²). 2 ), the amount of charge transferred (coulombic efficiency in %), a resistance (in Ohms), and a capacity (in mAh). The performance of the battery cell can be determined based on the evolution of

[0246] Robic File No.: 22186-0080

[0247] HQ File No.: 0886-PCT - 34 - its rated capacity over cycles, its rated capacity as a function of charging and discharging rates, its rated capacity as a function of different operating temperatures and pressures, the evolution of its internal resistance, its coulombic efficiency, and its temperature. Therefore, determining the pressure and temperature profile to be applied involves analyzing, from the collected data, at least one characteristic among: conductivity (S / cm) and critical current density (mA / cm²). 2 ), the coulombic efficiency (%), and the capacity (mAh) of the cells, and identify the applied pressure and temperature profile that maximizes at least one of these characteristics.

[0248] At the end of cycle sequence 170, one or more additional cycle sequences may be repeated until sufficient data is collected to determine the temperature and pressure to be applied to the battery cell to maximize its performance in a given operating mode. In some cases, for a given operating mode, the temperature and pressure must be varied according to the power demand or return of that mode. In these cases, a pressure and / or temperature profile may include the temperatures and / or pressures to be applied based on the current injected or consumed. For some operating modes, it may be determined that the pressure and temperature must be fixed. For example, for a cell at rest with a given chemical composition, it may be determined that the cell must be kept at 0°C and 200 PSI. These values ​​could be different for a cell with a different chemical composition.Similarly, the test bench can determine that for rapid charging, all-solid-state cells of a given composition must be subjected to increasing pressures as the charge progresses. As another example, the proposed method can identify, for a given chemical composition, the pressure and / or temperature to be applied during a significant discharge, such as accelerating a sports car uphill. The cycling sequences can therefore involve drawing or injecting power into each battery according to power profiles, or equivalent voltage or current profiles, corresponding to previously recorded real-world driving situations. The proposed method also allows for the parallel testing of cells with different sizes and / or chemical compositions, including lithium, nickel, cobalt, manganese, graphite, sulfur, sodium, etc.

[0249] Identifying the temperature and pressure profiles to apply to maximize battery performance for a given operating mode can be achieved using algorithmic tools and / or artificial intelligence models. These algorithmic tools and / or

[0250] Robic File No.: 22186-0080

[0251] No. HQ File: 0886-PCT - 35 - Artificial intelligence models, using for example linear regression analyses and / or objective functions, aim to identify the pressure and / or temperature values ​​maximizing one or more battery cell performance indicators, such as coulombic efficiency, capacity, etc.

[0252] In one possible implementation of the method, the casing material can vary from one casing to another. Battery cells of the same chemical composition can be placed in casings made of different materials and cycled and subjected to varying pressure and temperature conditions via the surrounding fluid, in order to identify the casing material that maximizes battery cell performance. Casing materials can include steel, aluminum, carbon fiber, and / or magnesium, or a combination thereof.

[0253] In one possible implementation of the method, tests can be performed to meet thermal shock resistance standards. For example, lithium-ion (Li-ion) batteries must comply with UL1642. Other possible standards include IEC62133, IEC62660, ISO 12405, and SAE J 2464, to name just a few. Traditional methods for testing compliance with these standards require physically moving cells from one chamber to another within a test apparatus, as the temperature differs between chambers. Companies like Espec™ and Intertek™ market such apparatus. This test bench allows for thermal cycling tests to be performed without the need to physically move cells between chambers.The proposed test bench and its operating method allow battery cells to be subjected to sudden or prolonged temperature variations much more effectively by controlling the temperature of the fluid circulating within the test bench housings. Thus, depending on one possible implementation of the method, the various pressure and temperature profiles applied to the cells can correspond to the profiles required for thermal shock testing. A battery cell can therefore be placed in a housing, a fluid circulated through it at a given temperature (e.g., -20 degrees Celsius) for a given period (e.g., 4 hours), and then, by controlling the temperature of the fluid upstream of the housing, a fluid circulated at another temperature (e.g., +70 degrees Celsius) for another given period (e.g., 4 hours). Indicative data on battery performance can then be collected by subjecting the cell to different cycling sequences.It is also possible to vary the temperature of the fluid in the housings until a break, thermal runaway and / or an internal short circuit occurs.

[0254] Robic File No.: 22186-0080

[0255] No. HQ File: 0886-PCT - 36 - detected, to identify the temperature limits to which a battery cell can be exposed.

[0256] With reference to Figures 11 to 18, several battery cell parameters can be analyzed. For example, and with reference to Figure 11, the battery cell conductivity can be measured as a function of the applied fluid pressure. With reference to Figure 12, the critical current density of the battery cell can be measured as a function of the applied fluid pressure. With reference to Figure 13, the coulombic efficiency of the battery cell as a function of the number of cycles completed can be measured at different operating temperatures. With reference to Figure 14, the coulombic efficiency of the battery cell as a function of the number of cycles completed can be measured at different operating pressures. With reference to Figure 15, the battery cell resistance can be measured as a function of the operating pressure.Referring to Figure 16, the battery cell resistance can be measured as a function of operating temperature. Referring to Figure 17, the battery cell capacity as a function of the number of cycles performed can be measured at different operating pressures. Referring to Figure 18, the battery cell capacity as a function of the number of cycles performed can be measured at different operating temperatures.

[0257] Referring to Figure 19, two examples of state-of-charge (SOC) pressure control protocols over 4 cycles 202 are measured. The first control protocol 220 is at constant volume, while the second control protocol 230 is at constant pressure.

[0258] With reference to graphs 200 and 210, a cell cycle is shown. Each cycle 202 consists of a charge 204 or current injection, which is generally associated with an increase in cell volume / thickness 214, and a discharge 206, which is generally associated with a decrease in cell volume / thickness 216.

[0259] With reference to Figure 220, a first control protocol 220 is illustrated as an example. Control 220 is a constant cell volume control, meaning that no additional volume is created in the casing 20 by the control system 50 (constant quantity of fluid), resulting in an increase 224 in the pressure inside the casing 20 as the cell volume increases 214 during charging 204. The pressure value decreases 226 during discharging 206, while the cell volume decreases 216. Breathing, or variation in cell volume, is not permitted in this type of control. This is referred to as mechanical constraint.

[0260] Robic File No.: 22186-0080

[0261] HQ File No.: 0886-PCT - 37 - With reference to Figure 230, a second control protocol 230 is illustrated as an example. Control 230 is a constant pressure control 238, meaning that the fluid pressure is continuously regulated by the control system to maintain a constant pressure. During charging 204, a quantity of fluid is discharged from the casing 20 by the control system 50 as the cell volume increases 214. During discharging 206, as the cell volume decreases 216, a quantity of fluid is injected into the casing 20 by the control unit 50. Breathing, or cell volume variation, is thus permitted in this type of control. Other pressure management protocols might, for example, allow partial cell breathing during a cycle.

[0262] Once all cycling sequences are complete, the optimal pressure and temperature to be applied to the battery cell are determined from the collected data. In one embodiment, determining the optimal pressure and temperature from the collected data is performed by a processor, software, measurement systems, and an artificial intelligence (AI) module. Specifically, by analyzing the data collected by the battery sensors, the AI ​​algorithms can predict future performance issues, optimize charging cycles, and extend battery life. These algorithms can learn from past data to improve predictions over time, in addition to integrating real-time operating data to create optimal operating conditions for the battery technology used.Predictive models can also identify early signs of potential failures, such as dendrite formation in the electrolyte layer, and trigger protective measures before the battery is damaged.

[0263] Based on the battery state of health (SOH) analysis, a self-healing protocol can be applied. By modulating the operating pressure and temperature of the cells for a few cycles according to specific patterns, it is possible to restore a battery's health. This self-healing protocol is an example of a pressure and temperature control protocol that the test bench described here makes possible.

[0264] The present method, as described above, refers to a single housing 20, but it is understood that the method is also applicable to a plurality of housings 20, 20', 20", with the cycling of the plurality of housings 20, 20', 20" being carried out in parallel and simultaneously. The cycling sequence and the pressure and temperature control protocol can be the same.

[0265] Robic File No.: 22186-0080

[0266] HQ File No.: 0886-PCT - 38 - for all 20, 20', 20" cases under test, or may be different for each of the 20, 20', 20" cases under test.

[0267] Similarly, the 40 battery cells contained in the 20, 20', 20" cases under test can be of different types, each battery cell having a specific size and chemical composition. For each battery cell under test, the method makes it possible to determine the optimal pressure and temperature for each of the different batteries, in one or more operating modes.

[0268] Finally, the 20, 20', 20" cases under test can be of different types and made of different materials including but not limited to steel, aluminum, magnesium, carbon fiber or any other suitable material.

[0269] Possible applications of the proposed method

[0270] The applications that can be performed with the proposed test bench and method are numerous. They may include:

[0271] The conditioning of new cells

[0272] The conditioning of cells (several of which form a battery) prior to cycling, by generating specific pressure and temperature values ​​during the initial "formation" cycles of newly manufactured cells, aims to consolidate their chemical structure before use / cycling. Each new cell (for most chemistries) must undergo this protocol. The advantage of the proposed test bench is that these parameters can be automatically modified by the control system to switch from "battery formation" to "battery cycling."

[0273] Cell cycling

[0274] As described previously, one possible application of the proposed test bench is cell cycling and the determination of optimal operating pressure and temperature values ​​to maximize cell performance. Cell performance indicators were defined in the background section.

[0275] The test bench can completely prevent cell volume variation during cycling, which may be necessary for certain chemistries. Systems that do not apply isostatic pressure cannot perform this function, nor can systems that generate isostatic pressure using a compressible fluid.

[0276] Robic File No.: 22186-0080

[0277] HQ File No.: 0886-PCT - 39 - The proposed test bench can guarantee uniform pressure across the entire cell. Furthermore, the test bench allows for precise determination of the pressure applied to the cell. Existing systems measure a force. The pressure is therefore deduced from the estimated area of ​​pressure application and is based on the assumption that this force is applied equally across the entire surface.

[0278] Self-healing treatment protocol

[0279] One advantage of this test bench is its ability to automatically change the pressure and temperature applied to the cells to switch from "cell cycling" to "self-healing" and then back to "stack cycling".

[0280] Thermal shock type safety tests

[0281] This test bench allows for thermal shock safety testing to be performed much more efficiently and quickly than with existing equipment. Furthermore, the system's advantage lies in the fact that these safety tests can be carried out after or during the cycling of a cell (or battery) in its casing, without having to handle the cell or move it. In addition, the testing and / or development of new cell chemistries can be performed more safely than with traditional methods / equipment, as new chemistries can be unstable or highly reactive. Real-time monitoring of the conditions to which the batteries are subjected, as well as the overpressure mechanisms integrated into the casings, enable safer testing.

[0282] Advantages of the method

[0283] Dynamic pressure adjustment in all-solid-state batteries is an advanced approach to optimizing battery performance and durability in real time. This technique involves continuously monitoring and adapting the pressure exerted on battery components and their operating temperature in response to variations in operating conditions, such as ambient temperature, charge / discharge cycle, and battery health.

[0284] The sensors integrated into the test bench 10, such as the thermocouple 39 and / or the pressure gauge 33, monitor critical parameters such as internal pressure and temperature. These sensors send real-time data to a control system. The controller 90 dynamically adjusts the pressure exerted on the battery cell and its operating temperature based on the received data. This can be achieved by the servo system 50 which

[0285] Robic File No.: 22186-0080

[0286] HQ File No.: 0886-PCT - 40 - applies variable pressure to maintain optimal contact between the electrodes and the solid electrolyte.

[0287] By adjusting pressure and temperature according to operating conditions, the battery cell can maintain optimal performance throughout its lifecycle, with improved ionic conductivity and reduced energy losses.

[0288] Dynamic pressure and temperature control can also prevent the formation of defects, such as cracks or delamination, which are often caused by mechanical or thermal stresses, thus extending the life of the stack.

[0289] Security-related aspects

[0290] Furthermore, the ability to adjust pressure and temperature in response to abnormal conditions, such as overheating, improves overall battery safety, reducing the risk of catastrophic failure. The proposed test bench offers enhanced operational safety through dynamic immersion cooling (oil circulation versus a static, fixed oil bath). Safety is further enhanced by the fact that the fluid circulates (effectively dissipating / injecting heat) and that the temperature of this injected fluid can be selected (for example, a very low value). The test bench also allows for increased operational safety through the application of a significant isostatic pressure, if necessary, which can delay or prevent certain chemical reactions.

[0291] The method also allows for a better response to changing conditions: for example, if the battery cell temperature increases, the test bench can reduce the pressure to prevent material deformation. Conversely, during intensive charge / discharge cycles, it can increase the pressure to improve conductivity and reduce internal resistance.

[0292] Finally, the test bench helps to compensate for volume changes during cycling: during charge and discharge cycles, volume changes occur in the electrodes (particularly in the lithium-metal anodes). If these changes are not properly managed, they can lead to electrolyte detachment from the electrodes, thus increasing internal resistance and reducing battery life. Pressure regulation allows for adaptation to these volume changes.

[0293] Modifications and additions may be made to the embodiments described above without departing from the invention.

[0294] Robic File No.: 22186-0080

[0295] No. HQ File: 0886-PCT - 41 -

Claims

CLAIMS:

1. A method for operating a test bench for determining the respective pressures and temperatures to be applied to battery cells for different operating modes, the method comprising the following steps: placing the battery cells in test bench housings, the housings being hermetically sealed, each housing containing one battery cell and comprising electrical connection terminals, a fluid inlet port and a fluid outlet port; injecting, by means of a test bench control system connected to the fluid inlet and outlet ports of the housings, a fluid applying isostatic pressure to the battery cells; applying, by means of a cycling device connected to the connection terminals of the housing, cycling sequences to the cells, the cycling sequences corresponding to the different operating modes; during the application of the cycling sequences,to vary, via the control system, the temperature and / or pressure of the fluid in each of the housings, independently from one housing to another, according to different pressure and temperature profiles; to detect, via sensors connected to the housings, parameters indicative of the performance of the battery cells; to collect, via a controller connected to the sensors, data derived from said parameters; and to determine, from said data, by the same or another controller, for each of the operating modes, a pressure and temperature to be applied to a given battery cell to maximize its performance.

2. The method according to claim 1, wherein applying the cycling sequences corresponding to distinct operating modes, comprises: Robic File No.: 22186-0080 HQ File No.: 0886-PCT - 42 - apply to at least one of the cells: a continuous power return, corresponding to a battery recharge; and apply to at least one other of the cells, at least one of the following cycling patterns: an alternation of power demand and power return, corresponding to accelerations followed by braking during driving; no power demand or return, corresponding to a battery at rest or in storage; and a reduced power demand, representing a low-speed driving condition.

3. The method according to claim 1 or 2, wherein applying the cycling sequences corresponds to making a call or a power injection on each battery according to power profiles, or equivalent voltage or current profiles, corresponding to real driving situations previously recorded.

4. The method according to claim 1, 2 or 3, wherein at least two of the cells have a distinct size and / or chemical composition(s).

5. The method according to any one of claims 1 to 4, wherein the injected fluid is incompressible.

6. The method according to any one of claims 1 to 5, wherein varying the temperature of the fluid comprises controlling, by the control system, the mixing of two fluid lines having different temperatures, upstream of the housings.

7. The method according to any one of claims 1 to 6, wherein varying the fluid pressure comprises controlling, by the control system, the flow rate at the inlet and / or outlet of the fluid in each of the housings.

8. The method according to any one of claims 1 to 7, wherein the applied fluid pressure varies between 10 PSI and 2500 PSI. Robic File No.: 22186-0080 No. HQ File: 0886-PCT - 43 - 9. The method according to any one of claims 1 to 8, wherein the fluid temperature varies between -20°C and 80°C.

10. The method according to any one of claims 1 to 9, wherein the detected parameters include at least one of: a temperature inside the housings; a pressure in the housings; a current, a voltage or a power, and / or a derivative thereof, across the terminals of the housings.

11. The method according to any one of claims 1 to 10, wherein determining the pressure and temperature to be applied, comprises: analyzing, from the collected data, at least one characteristic from among: the conductivity (S / cm), the critical current density (mA / cm²). 2 ), the coulombic efficiency (%), and the capacity (mAh) of the cells, and identify the pressure and temperature of the fluid in the housings that maximizes at least one of these characteristics.

12. The method according to any one of claims 1 to 11, wherein identifying the pressure and temperature maximizing at least one of said characteristics is carried out by algorithmic tools and / or artificial intelligence modules.

13. The method according to any one of claims 1 to 12, wherein at least two of the housings are composed of distinct materials, the method further comprising determining, on the basis of the data collected, the material which minimizes the pressure and / or brings the temperature to be applied to the fluid closer to a given ambient temperature, while maximizing the performance of the cells.

14. The method according to claim 13, wherein the material is selected from at least one of: steel, aluminum, carbon fiber, and magnesium.

15. The method according to any one of claims 1 to 14, wherein the pressure and temperature are varied and correspond to conditions required to conform to thermal shock tests. Robic File No.: 22186-0080 No. HQ File: 0886-PCT - 44 - 16. A test bench enabling the determination, for different modes of operation, of the respective pressures and temperatures to be applied to battery cells in order to maximize their performance according to different modes of operation, the test bench comprising: a set of housings which can be hermetically sealed, each housing being configured to house one of the battery cells and comprising electrical connection terminals, a fluid inlet port and a fluid outlet port, a servo system for injecting and / or removing, through the fluid inlet and outlet ports of the housings, a fluid applying an isostatic pressure on the battery cells and for varying the temperature and / or pressure of the fluid in each of the housings independently from one housing to another, according to different pressure and temperature profiles;a cycling device connected to the connection terminals of the housings to apply different cycling sequences to the cells, the cycling sequences corresponding to distinct operating modes; sensors to detect or read parameters indicative of, or affecting, battery performance; and one or more controllers to control the servo system and vary the pressure and / or temperature of the fluid, to control the cycling module by indicating the cycling sequences to be applied, to collect data derived from the detected parameters, and to determine, for each of the operating modes, a pressure and temperature to be applied to a given battery cell to maximize its performance.

17. The test bench according to claim 16, configurable between: - a servo-controlled mode in which the inlet fluid port and / or the outlet fluid port are connected to the servo system, allowing the isostatic pressure and / or temperature of the fluid to be regulated, and Robic File No.: 22186-0080 No. HQ File: 0886-PCT - 45 - - a passive mode in which the inlet fluidic port and the outlet fluidic port are closed, and in which the fluid pressure is isostatic and invariable for the duration of one or more of the cycling sequences.

18. The test bench according to claim 16 or 17, wherein the cycling device is configured to apply a power draw or injection to each battery according to current and / or power profiles recorded in memory, and corresponding to previously collected real driving situations.

19. The test bench according to claim 16, 17 or 18, comprising two fluidic lines at different temperatures and a proportional distributor associated with each of the lines to vary the temperature of the fluid.

20. The test bench according to any one of claims 16 to 19, wherein the servo system is configured to apply, independently in each of the housings, fluid pressures between 10 PSI and 2500 PSI.

21. The test bench according to any one of claims 16 to 20, wherein the control system is configured to apply fluid temperatures between -20°C and 80°C.

22. The test bench according to any one of claims 16 to 20, wherein the sensors include temperature sensors associated with control ports of each of the housings; pressure sensors associated with the fluidic inlet and / or outlet ports of the housings; a current, voltage and / or power detector associated with the terminals of the housings.

23. The test bench according to any one of claims 16 to 22, wherein the housings each comprise a pressure relief valve connected to the fluid outlet port, the pressure relief valve allowing the fluid to be evacuated in case of overpressure.

24. The test bench according to any one of claims 16 to 23, wherein the housings each comprise a rupture disc, the rupture disc being configured to fracture at a predetermined pressure value and allowing Robic File No.: 22186-0080 No. HQ File: 0886-PCT - 46 - to an excess of gas and / or fluid being evacuated to the outside in the event of thermal runaway.

25. The test bench according to any one of claims 16 to 24, wherein the controller(s) include one or more memory modules storing: the cycling sequences to be applied by the cycling device, the different pressure and temperature profiles to be applied by the control system for each operating mode to be tested, and the collected data derived from the detected parameters.

26. The test bench according to any one of claims 16 to 25, wherein the controller(s) comprise algorithmic tools and / or artificial intelligence modules configured to identify the pressure and temperature maximizing, for each of the battery cells tested, at least one of the following: conductivity (S / cm), critical current density (mA / cm²). 2), the coulombic efficiency (%), and the capacity (mAh) of the cells, for each of the distinct operating modes.

27. The test bench according to any one of claims 16 to 26, wherein at least two of the housings are composed of distinct materials, selected from at least one of: steel, aluminum, carbon fiber, and magnesium. Robic File No.: 22186-0080 No. HQ File: 0886-PCT - 47 -

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