Energy management process and energy storage module

Abstract

Energy management method and energy storage module. Energy storage module (1), comprising at least one electrochemical accumulator (2) configured to store energy in chemical form, a compression device (3) configured to apply pressure to said at least one electrochemical accumulator (2), the compression device (3) comprising a system (4) configured to vary the pressure at a frequency strictly greater than 0.01 Hz and less than or equal to 4 Hz. Figure for the abstract: Fig. 8

Description

Title of the invention: Energy management method and energy storage module technical field

[0001] The present invention relates to the field of electrical energy storage management, and more particularly to electrochemical accumulators with liquid electrolyte. STATE OF THE ART

[0002] Electrochemical accumulators are currently used to store energy in chemical form and to release some of the stored energy to power electrical devices. Electrochemical accumulators are also called "cells," and more generally, chemical energy storage cells. Accumulators can be lithium-ion based, or based on other lithium chemistries, such as lithium metal, or based on the intercalation of other ions, such as sodium-ion or potassium-ion chemistries within a battery system. Furthermore, accumulators comprise two electrodes and a separator placed between them. The separator's function is to provide electrical insulation between the electrodes and also to conduct ionic currents between them to ensure the movement of charges between the electrodes.More specifically, an electrochemical system placed between the two electrodes may include a liquid electrolyte to ensure ionic conduction. Furthermore, a battery includes a casing, also called a housing, which can be rigid (for rectangular batteries) or flexible, for example, in the form of a bag. This casing also ensures a watertight connection between the electrodes and an electrical circuit external to the battery. Electrical conduction elements are also integrated into batteries to ensure the electrical connection between the electrodes and electrical terminals, known as external or power terminals, of the battery. The external terminals are used to electrically connect a battery to the external electrical circuit.

[0003] An energy storage module, also called a battery module, generally comprises an association of these accumulators in series, to obtain higher voltages, and in parallel to obtain larger capacities, and therefore larger stored energies.

[0004] In general, it is advantageous to be able to increase the electrical performance of an electrochemical accumulator, for example its charge capacity to store more energy, or its discharge capacity to provide more energy.

[0005] For example, international application WO2021 / 201354 discloses a system for managing the lifespan of an electrochemical battery, in which the electrochemical battery can be excited at low frequencies, below 0.001 Hz, and at various surface pressure levels using a piezoelectric element. However, the system is complex and does not allow for a significant improvement in the electrical performance of an electrochemical accumulator. SUMMARY

[0006] One object of the invention is to overcome these drawbacks, and more particularly to provide means to improve the electrical performance of an electrochemical accumulator.

[0007] According to one aspect of the invention, an energy management method is proposed, comprising the provision of an energy storage module, the module comprising at least one electrochemical accumulator configured to store energy in chemical form, the method comprising applying pressure to said at least one electrochemical accumulator. The pressure is applied variably at a frequency strictly greater than 0.01 Hz and less than or equal to 4 Hz.

[0008] Thus, the storage and discharge capacity of a battery is improved. Surprisingly, the inventors were able to improve electrical performance by applying pressure variations at a frequency strictly greater than 0.01 Hz and less than or equal to 4 Hz.

[0009] According to another aspect of the invention, an energy storage module is proposed, comprising at least one electrochemical accumulator configured to store energy in chemical form, and a compression device configured to apply pressure to said at least one electrochemical accumulator. The compression device comprises a system configured to vary the pressure at a frequency strictly greater than 0.01 Hz and less than or equal to 4 Hz. BRIEF DESCRIPTION OF THE FIGURES

[0010] Other objects, features and advantages of the present invention will become apparent upon examination of the following detailed description and accompanying drawings in which:

[0011] [Fig. 1] The [Fig. 1] represents a method of implementing an energy management process;

[0012] [Fig.2] [Fig.2] represents a curve of pressure applied to an accumulator and a curve of the battery voltage over time;

[0013] [Fig. 3] [Fig. 3] represents voltage curves of a battery as a function of the charging capacity during a battery charge;

[0014] [Fig.4]

[0015] [Fig.5]

[0016] [Fig.6]

[0017] [Fig. 7] Figures 4 to 7 represent curves of the voltage of a battery as a function of the discharge capacity during a discharge of the battery; and

[0018] [Fig.8]

[0019] [Fig. 9] Figures 8 and 9 respectively represent two embodiments of an energy storage module and an associated charging infrastructure

[0020] The drawings are given by way of example and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. DETAILED DESCRIPTION

[0021] Before beginning a detailed review of embodiments and implementations of the invention, optional features that may possibly be used in association or alternatively are stated below.

[0022] According to one example, the pressure is applied variably at a frequency less than or equal to 1 Hz.

[0023] Optionally, the pressure is applied variably so that the pressure is greater than or equal to a minimum pressure greater than or equal to 0.1 bar.

[0024] Optionally, the pressure is applied variably so that the pressure is less than or equal to a maximum pressure less than or equal to 50 bars.

[0025] According to one example, the pressure is applied variably according to a pressure amplitude variation greater than or equal to 1 bar.

[0026] According to another example, the pressure is applied variably according to a pressure amplitude variation less than or equal to 10 bars.

[0027] In one embodiment, the module includes first 5 and second 6 electrical terminals, referred to as power terminals, electrically coupled to said at least one electrochemical accumulator 2, and the pressure is applied variably when a current flows between the first and second power terminals 5, 6.

[0028] According to one example, a current flows between the first and second power terminals 5, 6 during a reference time interval, and the pressure is applied variably over a period (Tpulse) strictly less than the reference time interval.

[0029] The pressure can be applied variably according to a periodic signal.

[0030] According to one option, the pressure is applied variably so that the amplitude of the pressure is constant.

[0031] In one example, said at least one electrochemical accumulator 2 comprises a liquid electrolyte located between two electrodes of said at least one electrochemical accumulator 2.

[0032] In one embodiment, the system 4 is configured to vary the pressure at a frequency less than or equal to 1 Hz.

[0033] System 4 is preferably configured to vary the pressure so that the pressure is greater than or equal to a minimum pressure greater than or equal to 0.1 bar.

[0034] Optionally, system 4 is configured to vary the pressure so that the pressure is less than or equal to a maximum pressure less than or equal to 50 bar.

[0035] According to one example, the system 4 is configured to vary the pressure according to a pressure amplitude variation greater than or equal to 1 bar.

[0036] In one case, the system 4 is configured to vary the pressure according to a pressure amplitude variation less than or equal to 10 bars.

[0037] An example is a module comprising first 5 and second electrical terminals, called power terminals, electrically coupled to at least one electrochemical accumulator 2, and in which the system 4 is configured to vary the pressure when a current flows between the first and second power terminals 5, 6.

[0038] In one embodiment, a current flows between the first and second power terminals 5, 6 during a reference time interval, and the system 4 is configured to vary the pressure over a period (Tpulse) strictly less than the reference time interval.

[0039] System 4 is configured, for example, to vary the pressure according to a periodic signal.

[0040] In one case, the system 4 is configured to vary the pressure so that the pressure amplitude is constant.

[0041] Possibly, said at least one electrochemical accumulator 2 comprises a liquid electrolyte located between two of said at least one electrochemical accumulator 2.

[0042] According to one example, the system 4 includes a surface intended to be in contact with the accumulator to apply the variable pressure.

[0043] Figures 1 and 2 illustrate the main stages of an energy management process. The term "energy management process" should be understood in a broad sense, that is, as a process implemented using an energy storage device. Thus, the management process allows for the control of the charging (i.e., storage) and discharging of an energy storage device, as well as possible intermediate phases without charging or discharging of the storage device. The energy management process is not limited to the charging (storage) process itself. Figures 3 to 7 show various curves illustrating the improvements in the electrical performance of an electrochemical accumulator using the process shown in Figures 1 and 2. Figures 8 and 9 show examples of the implementation of an energy storage module 1.

[0044] Generally, the module 1 comprises at least one electrochemical accumulator 2, referred to as a cell, and a compression device 3. Each accumulator 2 is configured to store energy in chemical form. In particular, an accumulator 2 comprises a liquid electrolyte located between two electrodes of the accumulator 2. Generally, the separator of the accumulator 2 is solid and porous to contain a liquid electrolyte, the electrolyte also being called an ionic conducting medium.

[0045] The compression device 3 is configured to apply pressure to at least one accumulator 2.

[0046] In particular, the compression device 3 includes a system 4 configured to vary the pressure at a frequency strictly greater than 0.01 Hz and less than or equal to 4 Hz. That is to say, the system 4 is configured to vary the pressure applied to an accumulator 2.

[0047] In addition, the energy management method includes a supply of module 1 as described above, and a main step in which pressure is applied to an accumulator 2 in a variable manner at a frequency strictly greater than 0.01 Hz and less than or equal to 4 Hz.

[0048] Advantageously, during an electrical charge or discharge of a module 1, a variable mechanical compressive stress Fl is applied to one or more cells 2 so as to vary the pressure exerted on the cell(s) 2. For example, the pressure variation, i.e., the variation in the pressure amplitude, is less than or equal to 10 bar. More particularly, the variable pressure exerted on the accumulator is greater than or equal to 0.1 bar, for example, greater than or equal to 1 bar. Advantageously, the pressure variation is less than or equal to a maximum pressure less than or equal to 50 bar.

[0049] For example, the stress Fl applied to the accumulator 2 allows a pressure to be exerted oscillating between a minimum value (strictly greater than 0 bar) and a maximum value (of 50 bar). The frequency of the oscillations is between 0.01 Hz and 4 Hz, preferably less than or equal to 1 Hz.

[0050] Figures 1, 8 and 9 show a charging infrastructure 30 associated with a module 1. Module 1 comprises first 5 and second 6 electrical terminals, referred to as power terminals, electrically coupled to the electrochemical accumulators 2 of module 1. The power terminals 5, 6 are intended to be electrically coupled to a charging infrastructure 30, via electrical connections 8, 9. The charging infrastructure 30 includes an external circuit 7. The external circuit 7 can be a source of electrical power to charge the batteries 2 of module 1. Alternatively, the external circuit 7 can be an electrical device that discharges the batteries 2 to operate. Generally, the compression system 4 can be controllable. For example, the system 4 can be supplied by a fluid 10 pressurized by a compressor IL. To compress one or more cells 2 simultaneously, the system 4 can include a fluidic actuator 20 of the hydraulic or pneumatic type (for example, an inflatable bladder).A bladder offers the advantage of a compact design, a working pressure range of 0 to 10 bar (for an industrial pneumatic bladder), and up to 250 bar (for an industrial hydraulic bladder), and the ability to be configured for pressure control. It should also be noted that a pneumatic actuator is particularly well-suited for vehicles or installations already equipped with pressurized fluid networks (pneumatic, cooling). Alternatively, the system can include other adjustable compression devices, such as electric cylinders, piezoelectric actuators, mechanical cam actuators, or strap or rope tensioners, etc.

[0051] Figure 8 shows an embodiment in which the module 1 comprises a housing 12 containing the accumulators 2. The housing 12 can be integrated within a battery 13. The battery 13 further comprises two electrical terminals 14, 15, referred to as main terminals, electrically coupled to the power terminals 5, 6 of the module 1, respectively. The battery 13 may include a communication line 16 for exchanging data with an external electronic circuit, for example, a battery management circuit. For example, the battery 13 comprises a fluid reservoir 17, a fluid distributor 18 fluidically coupled to the reservoir 17 and to the fluidic actuator 20, so as to manage the quantity of fluid supplied to the fluidic actuator to exert the pressure variation on at least one accumulator 2 of the module 1.In addition, the battery 13 includes a compressor 11 fluidically coupled to the reservoir to supply the fluidic actuator with pressurized fluid. According to a variant illustrated in [Fig. 9], the fluid distributor 18, the reservoir 17 and the compressor 11 are located outside the battery 13. In this case, the battery 13 is equipped with a fluidic fitting 21 configured to fluidly couple the fluidic actuator 20 of module 1 with the fluid distributor 18.

[0052] Advantageously, the system 4 includes a surface 22 intended to be in contact with at least one accumulator 2 to apply the variable pressure to the accumulator 2. In the case of prismatic cells, the compressive stress can, for example, be applied to a face, called the principal face, of a cell 2 (the cell 2 being isolated or part of a set of cells 2). Alternatively, two compressive stresses can be exerted on the two opposite faces of an isolated cell 2, or on the principal faces of two cells 2 located at the ends of a set of cells 2. Preferably, each compressive stress is exerted in a direction orthogonal to a principal face.

[0053] For example, the pressure is applied variably when a current flows between the first and second power terminals 5, 6. That is, a variable pressure is applied to the accumulators 2 when the power terminals 5, 6 are connected to the external circuit 7, during the charging or discharging of the accumulators 2. Advantageously, a current flows between the first and second power terminals 5, 6 for a reference time interval, and the pressure is applied variably over a period strictly shorter than the reference time interval. The reference time interval can be the charging time of module 1, or the discharging time of module 1. In other words, the pressure variation can be applied at a relatively high frequency compared to the charging or discharging time (for example, from 0.1 to 4.0 Hz).

[0054] It has been shown by experience that this cyclic compression improves the restored capacity of cells 2, particularly when charging or discharging at low temperature (i.e., for temperatures below 5°C).

[0055] The term "returned capacity" refers to the amount of energy stored by module 1.

[0056] Thus, mechanical pulsations promote ionic mobility (ionic mobility being a limiting factor in energy storage capacity) by creating convection within the electrolyte. One of the main limitations of batteries 2 is the ionic conductivity of their electrolyte. The value of the ionic conductivity determines the possible migration distance of ions in a porous electrode at a given operating regime. For example, for a lead-acid aqueous battery, the conductivity of the electrolyte is on the order of 100 mS / cm, which allows the manufacture of porous electrodes on the order of 1 mm thick to withstand discharges on the order of an hour. For a lithium-ion battery, the conductivity of the electrolyte is limited to approximately 10 mS / cm, which necessitates limiting the thickness of the electrodes to 0.1 mm to obtain acceptable performance over one-hour discharges.In particular, for electric vehicle batteries with a negative electrode approximately 100 µm thick, prior art processes allow the recovery of about 90% of the theoretical capacity for a one-hour discharge, but only 40 to 80% of the capacity for a 30-minute discharge. At the microscopic level, this can be explained by the limited mobility of lithium ions relative to a given current regime. Indeed, if the reaction rate at the particle interface is faster than the migration / diffusion rate of the ions in the electrolyte, then... A concentration gradient develops within the porous structure of the electrode. During rapid charging, for example, the available ion concentration in the part of the negative electrode furthest from the separator will decrease to 0, at which point further charging of the battery is no longer possible. To overcome this limitation, one can try to increase the conductivity of the electrolyte (for example, by increasing the temperature when possible) or decrease the thickness of the electrodes, at the expense of the cell's energy density.

[0057] Thus, thanks to mechanical pulsations, convection is created within the electrolyte to limit ion concentration gradients.

[0058] By compressing cell 2, it is deformed. For a pressure of 10 bars or IMpa, the anode, the cathode and the separator of a cell 2 will deform by a few micrometers.

[0059] The pressure must be sufficient to deform the cell (i.e. the pressure variation is greater than or equal to 0.1 bar), but low enough not to degrade it (<50 bars).

[0060] On the other hand, to equalize the concentration gradients, the frequency of the cyclic compression is preferably greater than the discharge time (for example strictly greater than 1 mHz).

[0061] Thus, during an electrical charge or discharge, a mechanical compressive stress Fl oscillating between a minimum value and a maximum value is applied to one or more cells 2, at a high frequency, that is to say a frequency strictly greater than 0.01 Hz.

[0062] In [Fig.2], a curve Cl of the electrical discharge of a cell 2 of module 1 is schematically represented, as well as a curve C2 of the mechanical pressure applied to a cell 2. For example, the discharge takes place between times t0 and tf.

[0063] A start-up time tl corresponds to the instant when the pulsations, i.e., pressure variations, begin. The start-up time tl is between t0 and tf. For example, if tl equals t0, then the pulsations are applied from the very beginning of the discharge. Advantageously, the start-up time tl can be defined according to a voltage at the power terminals 5, 6, a state of charge (SoC) of module 1, a state of health (SoH) of module 1, a conformity requirement (SoX) of module 1, a temperature, or a combination of the aforementioned parameters. For example, the start-up time tl could be the instant when the voltage drops below 3V.

[0064] A stopping time t2 corresponds to the instant when the pulses cease. The stopping time t2 can be between t0 and tf. For example, if the stopping time t2 is equal to tf, then the pulses are applied until the end of the discharge. The stopping time t2 can also be defined according to the voltage across the power terminals 5, 6, the state of module 1 SoC load, module 1 SoH health status, module 1 SoX compliance requirement, temperature, or a combination of the aforementioned parameters.

[0065] Generally, an initial pressure pO is applied to the cells 2 of module 1 during normal operation of module 1. The initial pressure pO corresponds to the pressure recommended by the cell 2 manufacturer during its nominal use. Generally, the initial pressure pO is below a maximum acceptable pressure that can be applied to the cells 2 without risk of damaging them. The initial pressure pO is between 0 and 10 bar, preferably between 0.1 and 1 bar.

[0066] A maximum pressure pmax is applied to the cells 2 during the pulsations. The maximum pressure pmax is below the maximum acceptable pressure pcc for the cells 2. Advantageously, the maximum pressure pmax can be strictly greater than the initial pressure pO to ensure sufficient deformation of the cell 2. The maximum pressure pmax can be between 0.1 and 50 bar. Preferably, the maximum pressure pmax is between 5 and 20 bar.

[0067] A minimum pressure pmin is applied to the cells during the pulsations. A difference between the minimum pressure pmin and the maximum pressure pmax ensures sufficient deformation of the cells 2. For example, the minimum pressure pmin is between 0 and 5 bar.

[0068] According to one embodiment, the minimum pressure pmin and maximum pressure pmax are less than or equal to the initial pressure pO. According to another example, the minimum pressure pmin is less than or equal to the initial pressure pO and the maximum pressure pmax is strictly greater than the initial pressure pO. According to yet another embodiment, the minimum pressure pmin and maximum pressure pmax are greater than or equal to the initial pressure pO. In all cases, the maximum pressure pmax is strictly greater than the minimum pressure pmin in order to ensure deformation of the cells 2.

[0069] A pulse period Tpulse corresponds to the period of the mechanical pressure pulses. The pulse frequency is high relative to the characteristic discharge (or charge) time, so as to produce several pulses during a discharge or charge. It should be noted that as the pulse frequency increases, the electrical performance of module 1 improves. The pulse period Tpulse is, for example, between 0.25 s and 10 s (i.e., the pulse frequency is between 0.1 Hz and 4 Hz). For example, the pulse period can be equal to 1 or 2 s.

[0070] For example, the pressure is applied variably according to a periodic signal. Alternatively, the signals are symmetrical, for example, the time when the pressure is greater than a reference pressure pref is equal to the time when the pressure is lower than the reference pressure. The reference pressure pref is between pmin and pmax, for example the reference pressure pref is equal to the initial pressure pO.

[0071] According to another example, the pressure is applied variably so that the amplitude of the pressure is constant.

[0072] Figure 3 shows various curves from a first test, with the charging capacity in ampere-hours on the x-axis and the voltage across power terminals 5 and 6 in volts on the y-axis. A first CCI charging curve of the charging capacity is shown when the initial pressure pO is equal to 20 bar and there is no pressure variation applied to cell 2 of module 1. A second CC2 charging curve of the charging capacity is shown when the initial pressure pO is equal to 1 bar and there is no pressure variation applied to cell 2 of module 1. A third CC0.5Hz charging curve of the charging capacity is shown when the initial pressure pO is equal to 20 bar and a pressure variation is applied to cell 2 of module 1 with a frequency of 0.5 Hz.A fourth CClHz load curve of the load capacity is shown when the initial pressure pO is equal to 20 bar and a pressure variation is applied to cell 2 of module 1 with a frequency of 1 Hz. The first test illustrates that the pulsations increase the load capacity of module 1. Furthermore, the first test shows that a pressure variation at 0.5 Hz increases the load capacity by 35%, and at 1 Hz, an increase of 60%. Thus, increasing the pulsation frequency improves the electrical performance of module 1.

[0073] Figure 4 shows two curves from a second test, with the discharge capacity in ampere-hours on the x-axis and the voltage across power terminals 5 and 6 in volts on the y-axis. A first discharge curve CD1 of the discharge capacity is shown when the initial pressure pO is equal to 1 bar and there is no pressure variation applied to cell 2 of module 1. A second discharge curve CD2 of the discharge capacity is shown when the initial pressure pO is equal to 20 bar and a pressure variation is applied to cell 2 of module 1 with a frequency of 0.5 Hz. The second test illustrates that the pulsations increase the discharge capacity of module 1. Furthermore, the second test shows that a pressure variation at 0.5 Hz increases the discharge capacity by 60%. Thus, a variation in the pressure exerted on cell 2 improves the electrical performance of module 1.

[0074] In [Fig. 5], various curves from a third test are shown, with the discharge capacity in ampere-hours on the x-axis and the voltage across the power terminals 5, 6 in volts on the y-axis. A first reference curve Crefl of The discharge capacity is shown when the initial pressure pO is equal to 20 bar and there is no pressure variation applied to cell 2 of module 1. A second reference curve, Cref2, of the discharge capacity is shown when the initial pressure pO is equal to 1 bar and there is no pressure variation applied to cell 2 of module 1. A third curve, ClHz, of the discharge capacity is shown when the initial pressure pO is equal to 20 bar and a pressure variation is applied to cell 2 of module 1 at a frequency of 1 Hz. The third test illustrates that the improvement in the electrical performance of module 1 is not solely due to the application of high pressure, which could reduce interface resistances. The cell discharged according to the first reference curve, Cref1, at a constant 20 bar exhibits the same discharge as in a reference configuration, Cref2, at a constant 1 bar.Only the application of a pressure variation at 1Hz improves the discharged capacity.

[0075] Figure 6 shows various curves from a fourth test, with the discharge capacity in ampere-hours on the x-axis and the voltage across power terminals 5 and 6 in volts on the y-axis. A first reference curve, Cref2, of the discharge capacity is shown when the initial pressure pO is equal to 1 bar and there is no pressure variation applied to cell 2 of module 1. A second curve, ClHz, of the discharge capacity is shown when the initial pressure pO is equal to 15 bar and a pressure variation is applied to cell 2 of module 1 with a frequency of 1 Hz. A third curve, C0.5Hz, of the discharge capacity is shown when the initial pressure pO is equal to 20 bar and a pressure variation is applied to cell 2 of module 1 with a frequency of 0.5 Hz. Furthermore, according to the third curve, C0.At 5Hz, the pulses are started during discharge, meaning that the pulse start time tl is greater than the discharge start time tO of module 1. The fourth test shows that even late-triggered pulses (tl>tO) increase the capacitance restored during a discharge.

[0076] Figure 7 shows two curves from a fifth test, with the discharge capacity in ampere-hours on the x-axis and the voltage across power terminals 5, 6 in volts on the y-axis. A first reference curve, Cref2, of the discharge capacity is shown when the initial pressure pO is equal to 1 bar and there is no pressure variation applied to cell 2 of module 1. A second curve, C0.5Hz, of the discharge capacity is shown when the initial pressure pO is equal to 20 bar and a pressure variation is applied to cell 2 of module 1 with a frequency of 0.5 Hz. Furthermore, according to the second curve, C0.5Hz, the pulses start late during discharge; that is, the pulse start time tl is much longer than the start time. t0 of the discharge of module 1. The fourth test shows that even pulses triggered very late (tl>(tf / 2)) increase the capacity restored during a discharge. In this case, by starting the pulses towards the end of the discharge, a 38% improvement in the discharge capacity of cell 2 is obtained.

[0077] Performance can also be improved at low temperature, in the case where ionic mobility in the electrolyte becomes very limiting, i.e. when the temperature of the environment of module 1 is less than or equal to 5°C, for example at 0°C.

[0078] The described method also allows, in the case of rapidly charged Li-ion cells (charging time <lh) d’éviter le phénomène de dépôt lithium (appelé « li plating » en langue anglaise) sur l’électrode négative.

[0079] The invention just described is suitable for many fields of application, such as land, air, and sea vehicles, etc...< / lh)>

Claims

Demands

1. Energy management method, comprising: • supplying an energy storage module (1), the module (1) comprising at least one electrochemical accumulator (2), configured to store energy in chemical form, • the method comprising applying pressure to said at least one electrochemical accumulator (2), characterized in that the pressure is applied variably at a frequency strictly greater than 0.01 Hz and less than or equal to 4 Hz.

2. A method according to the preceding claim, wherein the pressure is applied variably at a frequency less than or equal to 1 Hz.

3. A method according to any one of the preceding claims, wherein the pressure is applied variably so that the pressure is greater than or equal to a minimum pressure greater than or equal to 0.1 bar.

4. A method according to any one of the preceding claims, wherein the pressure is applied variably so that the pressure is less than or equal to a maximum pressure less than or equal to 50 bars.

5. A method according to any one of the preceding claims, wherein the pressure is applied variably according to a pressure amplitude variation greater than or equal to 1 bar.

6. A method according to any one of the preceding claims, wherein the pressure is applied variably with a pressure amplitude variation less than or equal to 10 bars.

7. A method according to any one of the preceding claims, wherein the module comprises first (5) and second (6) electrical terminals, referred to as power terminals, electrically coupled to said at least one electrochemical accumulator (2), and the pressure is applied variably when a current flows between the first and second power terminals (5, 6).

8. A method according to the preceding claim, wherein a current flows between the first and second power terminals (5, 6) during a reference time interval, and the pressure is applied variably over a period (Tpulse) strictly less than the reference time interval.

9. A method according to the preceding claim, wherein the pressure is applied variably according to a periodic signal.

10. A method according to any one of the preceding claims, wherein the pressure is applied variably so that the amplitude of the pressure is constant.

11. A method according to any one of the preceding claims, wherein said at least one electrochemical accumulator (2) comprises a liquid electrolyte situated between two electrodes of said at least one electrochemical accumulator (2).

12. Energy storage module (1), comprising: • at least one electrochemical accumulator (2), configured to store energy in chemical form, • a compression device (3) configured to apply pressure to said at least one electrochemical accumulator (2), characterized in that the compression device (3) comprises a system (4) configured to vary the pressure at a frequency strictly greater than 0.01 Hz and less than or equal to 4 Hz.

13. Module according to claim 1, wherein the system (4) is configured to vary the pressure at a frequency less than or equal to 1 Hz.

14. Module according to any one of the preceding claims, wherein the system (4) is configured to vary the pressure so that the pressure is greater than or equal to a minimum pressure greater than or equal to 0.1 bar.

15. Module according to any one of the preceding claims, wherein the system (4) is configured to vary the pressure so that the pressure is less than or equal to a maximum pressure less than or equal to 50 bar.

16. Module according to any one of the preceding claims, wherein the system (4) is configured to vary the pressure by a pressure amplitude variation greater than or equal to 1 bar.

17. Module according to any one of the preceding claims, wherein the system (4) is configured to vary the pressure by a pressure amplitude variation less than or equal to 10 bars.

18. Module according to any one of the preceding claims, comprising first (5) and second (6) electrical terminals, referred to as power terminals, electrically coupled to said at least one electrochemical accumulator (2), and wherein the system (4) is configured to vary the pressure when a current flows between the first and second power terminals (5, 6).

19. Module according to the preceding claim, wherein a current flows between the first and second power terminals (5, 6) during a reference time interval, and the system (4) is configured to vary the pressure over a period (Tpulse) strictly less than the reference time interval.

20. Module according to the preceding claim, wherein the system (4) is configured to vary the pressure according to a periodic signal.

21. Module according to any one of the preceding claims, wherein the system (4) is configured to vary the pressure so that the amplitude of the pressure is constant.

22. Module according to any one of the preceding claims, wherein said at least one electrochemical accumulator (2) comprises a liquid electrolyte located between two of said at least one electrochemical accumulator (2).

23. Module according to any one of the preceding claims, wherein the system (4) comprises a surface intended to be in contact with the accumulator to apply the variable pressure.

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