Battery comprising a reference electrode maintained at a stabilized reference potential.

Abstract

A metal-ion type battery comprising a negative electrode, a positive electrode, and an electrolyte extending between the negative electrode (10-) and the positive electrode (10+), as well as a reference electrode (10'ref) held at a reference potential; the battery comprising or being connected to: a Lithium discharge circuit (13+) of the reference electrode; and / or a Lithium charging circuit (13-) of the reference electrode; and; a control unit (15) configured to activate the Lithium charging circuit and / or the Lithium discharge circuit; the battery being characterized in that it comprises or is connected to: a potential buffer point (10'ref); a reference circuit (13ref), activated by the control unit, to transfer the reference potential to the potential buffer point when activated.

Description

Title of the invention: Battery comprising a reference electrode maintained at a stabilized reference potential. Technical field

[0001] The invention relates to metal-ion batteries, and in particular Lithium ion batteries. EARLIER ART

[0002] Metal-ion batteries are a class of rechargeable batteries where metal ions play a key role in energy storage and transfer. Among them, lithium-ion (Li-ion) batteries are the most common and are used in various devices, including smartphones, laptops, and electric vehicles. They operate by transferring lithium ions between the negative electrode (conventionally called the anode, usually graphite-based) and the positive electrode (conventionally called the cathode, often composed of LiMO2-type metal oxides, where M = transition metal, for example, Ni, Co, Mn) through an electrolyte. Their main advantage lies in their high energy density and their ability to deliver a large number of charge / discharge cycles, resulting in lighter and more durable batteries.

[0003] An important aspect for ensuring the safety and longevity of lithium-ion batteries is the metallic deposition of lithium on the anode, instead of its proper integration into the graphite anode structure. Such deposition is commonly referred to as "lithium plating." This occurs primarily during rapid or low-temperature charging, when lithium ions do not have enough time to diffuse efficiently into the active particles of the anode (high current) or accumulate at their interface (low temperature). Metallic lithium deposition can lead to the formation of dendrites, filamentous structures that can grow through the electrolyte and cause short circuits between the anode and cathode. This results in: - a reduction in available battery capacity by trapping lithium ions. - an increase in internal resistance, degrading battery performance. - a possibility of degradation through internal short circuits;

[0004] It is understood that lithium plating accelerates battery degradation, thus reducing its lifespan.

[0005] Application EP3072179 describes the use of a reference electrode, also called a comparison electrode, in addition to the anode and cathode. It is referred to as also includes a third electrode. The reference electrode is held at a known potential, considered fixed and constant over time. By measuring the potential difference between the comparison electrode and the anode or cathode, the evolution of the anode or cathode potential over time can be monitored. However, maintaining the operational status of this reference electrode requires either a complete recharge or a complete discharge to establish a reference point (fully charged or fully discharged electrode) before reactivating it through a partial discharge or recharge, which is time-consuming.

[0006] The invention described below makes it possible to limit, or even avoid, the formation of a metallic deposit known as Lithium plating, at the level of the anode, while being compatible with a fast battery charge or a charge carried out at low temperature thanks to access to the measurement of the anode potential continuously and reliably. Description of the invention

[0007] A first object of the invention is a metal-ion battery comprising a negative electrode, a positive electrode, and an electrolyte extending between the negative and positive electrodes, the negative electrode being configured to - release, by oxidation, positive metal ions, during a battery discharge, so that the positive metal ions migrate towards the positive electrode; - accept, by reduction, positive ions during battery charging;

[0008] the battery comprising a reference electrode, extending between the negative electrode and the positive electrode, held at a reference potential, the reference electrode being connected to a measuring circuit, configured to measure: - a difference between the potential of the negative electrode and the reference potential - and / or a difference between a potential of the positive electrode and the reference potential;

[0009] the battery comprising or being connected to: - a Lithium discharge circuit for the reference electrode, extending between the positive electrode and the reference electrode; - and / or a Lithium charging circuit for the reference electrode, extending between the reference electrode and the negative electrode and; - a control unit, configured to activate the Lithium charging circuit and / or the Lithium discharging circuit, so as to adjust the reference potential relative to a predetermined reference value;

[0010] the battery being characterized in that it comprises or is connected to: - a potential buffer value point; - a reference circuit, configured to be activated by the control unit, and to report the reference potential to the potential buffer value point when activated;

[0011] the battery being such that the measuring circuit extends between the potential buffer value point and the negative electrode and / or between the potential buffer value point and the positive electrode.

[0012] According to one possibility: - the reference circuit includes a switch; - the control unit is configured to drive the switch, so as to allow a transfer of the reference potential to the potential buffer value point.

[0013] According to one possibility, the control unit is configured to activate the Lithium charging circuit or the Lithium discharging circuit of the reference electrode, depending on a duration during which the reference circuit has been activated.

[0014] According to one possibility, the control unit is configured to: - to memorize a leakage current resulting from each activation of the reference circuit; - activate the Lithium charging circuit and / or the Lithium discharging circuit of the reference electrode according to an accumulation of leakage currents during several successive activations of the reference circuit.

[0015] According to one possibility, the control unit is configured to estimate the potential of the negative electrode and / or the potential of the positive electrode as a function of the potential difference measured by the measuring circuit.

[0016] According to one possibility, during battery charging, the control unit is configured to: - compare the potential of the negative electrode or the potential of the positive electrode to a predetermined threshold value; - adjust the intensity of the battery charging current based on the comparison.

[0017] The control unit can be located remotely from the battery. The control unit can be integrated into the battery.

[0018] A second object of the invention is a method for controlling a battery according to the first object of the invention, the method comprising a periodic activation of the Lithium charging circuit or the Lithium discharging circuit of the reference electrode so as to adjust the potential of the reference electrode with respect to a predetermined reference value.

[0019] The adjustment of the reference potential can be carried out without connecting the reference electrode to an external power source.

[0020] The method may include: - periodic activation of the reference circuit, so as to shift the reference potential to the potential buffer value point; - periodic measurement of a potential difference between the negative electrode and the potential buffer value point and / or between the positive electrode and the potential buffer value point; - periodic estimation of the potential of the negative electrode or the positive electrode as a function of the measurement of the potential difference.

[0021] According to one possibility, the Lithium charging circuit or the Lithium discharging circuit of the reference electrode is activated according to a cumulative duration of successive activations of the reference circuit.

[0022] According to one possibility, the method comprises, during a battery charge, during which the battery is supplied with a charging current: - measurement of a potential difference between the positive electrode and the potential buffer value point and / or between the negative electrode and the potential buffer value point. - adaptation of the charging current according to the measured potential difference(s).

[0023] The invention will be better understood upon reading the description of the exemplary embodiments presented later in this description, in connection with the figures listed below. FIGURES

[0024] Fig. 1 schematically illustrates an example of a battery according to the invention.

[0025] Figure 2 shows a charging curve and a discharging curve of a battery Lithium ion, with a Nickel-Manganese-Cobalt type cathode and a Graphite type anode.

[0026] Fig. 3 represents a profile of the Lithium charging or Lithium discharging potential of a LiFePO4 / FePO4 (or LFP) reference electrode: ordinate axis: unit V vs Li7Li) as a function of the capacitance associated with the lithiation state of the material forming the reference electrode (abscissa axis).

[0027] Figure 4 schematically illustrates a first embodiment of the invention.

[0028] Figure 5 schematically illustrates a second embodiment of the invention.

[0029] Figure 6A represents an evolution of the electrode potential (ordinate axis) as a function of time (x-axis) during a battery charge at high charging current and / or low temperature, respectively without implementing and implementing the invention.

[0030] Figure 6B shows an example of controlling the battery charging current intensity as a function of the negative electrode potential. Figure 6B shows the battery charging current intensity (ordinate axis) as a function of time (abscissa axis).

[0031] Figure 7 shows the main steps of a method for implementing a battery according to the invention. PRESENTATION OF SPECIFIC IMPLEMENTATION METHODS

[0032] In this description, the term negative electrode or the term anode will be used interchangeably to identify the same physical object regardless of whether the battery is charging or discharging, based on a naming convention based on the battery's operation in discharge mode (i.e. the service usually valued).

[0033] Similarly, the term positive electrode, or the term cathode, are used interchangeably to designate the same physical object, based on this same naming convention derived from the battery's discharge mode operation.

[0034] Figure 1 shows a schematic example of a Lithium-ion battery according to the invention. The battery comprises a positive electrode 10+ (cathode) and a negative electrode 10- (anode).

[0035] As mentioned in the prior art, the negative electrode 10- can be made of graphite. The positive electrode 10+ can be made of a transition metal oxide, for example LiNixMnyCozO2 (with x+y+z=l).

[0036] An electrolyte 11 extends between the positive and negative electrodes. It can, for example, be a lithium salt dissolved in either a liquid phase (solvents) or a solid phase (polymer or sulfides). The electrolyte can therefore be either solid or liquid.

[0037] During battery charging, positive metal ions, in this case Li+, migrate through the electrolyte towards the negative electrode 10-. The positive metal ions are produced by oxidation within the positive electrode, releasing electrons that circulate in the external circuit. During battery discharge, the negative electrode releases positive metal ions through oxidation, which then migrate towards the positive electrode. Figure 2 shows a charge and discharge curve of a Li-ion battery (voltage as a function of state of charge SOC).

[0038] The battery includes a reference electrode 10ref, interposed between the positive electrode 10+ and the negative electrode 10-. The LixFePO4 / FePO4 couple can notably form a reference electrode generally because it exhibits a potential plateau, at the value of 3.424V, over a wide range of its capacity or lithiation state (capacity at time t xlOO / total capacity), as shown by the charge / discharge curve represented in [Fig. 3] (potential as a function of capacity expressed as a percentage). Thus, For a large part of the capacitance, the potential of the reference couple chosen here (LixFePO4 / FePO4) is stable, close to 3.4 V. The presence of a potential plateau (constant value) over a wide range of lithiation states justifies that this material is suitable to serve as a reference electrode.

[0039] In an open circuit, this material exhibits low intrinsic self-discharge, estimated at 0.2 nAh / h at 25°C. However, when measuring the potential difference between the positive or negative electrode and the reference electrode, a leakage current develops, which can alter this property and shift the potential of the reference electrode towards higher lithiation states, and its value may no longer be at the plateau value. Depending on the value of the leakage current, this drift can occur more or less rapidly over time, considering that the capacitance of the reference electrode is low, consistent with its small dimensions. The dimensions of the reference electrode are reduced because its presence must not disrupt the proper functioning of ion exchange between the positive and negative electrodes.

[0040] The reference electrode 10ref is brought to a reference potential Uref, which corresponds to the potential plateau value. An important aspect of the invention is to use the reference potential, which is assumed to be stable over time, to measure the respective potentials U+ and U- of the positive electrode versus Uref and of the negative electrode versus Uref. This requires maintaining the reference potential as stable as possible throughout the battery's lifespan, i.e., over several months or years. Maintaining the reference potential at a stable value is another important aspect of the invention. The reference potential is brought to a predetermined reference value. This could be, for example, 50% of the electrode's lithiation state.The reference potential can be obtained from the fully lithium-filled electrode, or one that can be considered as such, from which a discharge of approximately 50% lithium is carried out, so that the reference potential is stable over time.

[0041] The battery also includes a measurement circuit 12+ of a potential difference Ui between the potential U+ of the positive electrode 10+ and the reference potential Uref, and / or a measurement circuit 12- of a potential difference U2 between the potential CL of the negative electrode 10- and the reference potential Uref.

[0042] U{-U+-Uref (ï) aü^=U.-UrefW

[0043] With the reference potential Urej controlled, the measurement circuit 12+ allows monitoring of the potential U+ of the positive electrode. The measurement circuit 12- allows monitoring of the potential U- of the negative electrode 10-. Depending on whether one wishes to monitor the evolution temporal of the potential of the positive electrode or the negative electrode, the battery includes the 12+ measurement circuit and / or the 12- measurement circuit.

[0044] Note that only one measurement can be carried out, either U+ or V-, knowing the potential difference Ucen between the positive electrode and the negative electrode. uceU= u+-u~

[0045] The battery includes a reference circuit 13ref, configured to connect the reference electrode 10ref to the measurement circuits 12+ and 12-, while minimizing a charge loss during the measurements of UiOuU2. It is understood that these measurements must be carried out by drawing the lowest possible current over the shortest possible periods.

[0046] In order to maintain the reference potential at the fixed reference value, it is necessary to maintain the lithium content of the reference electrode within a determined range, for example close to a median lithium filling level.

[0047] To do this, the battery includes - a Lithium 13+ discharge circuit of the reference electrode, interposed between the positive electrode 10+ and the reference electrode 10ref, and configured to ensure a passive but controlled electrical discharge between the positive electrode 10+ and the reference electrode 10ref so as to inject a discharge current ii into the reference electrode in order to lower its Lithium content (oxidation reaction) and thus increase the reference potential; - and / or a Lithium 13- charging circuit, interposed between the reference electrode 10ref and the negative electrode 10-, and configured to ensure a passive but controlled electrical discharge between the reference electrode 10ref and the negative electrode 10-, so as to draw a discharge current i2 from the reference electrode in order to increase its Lithium content (reduction reaction) and thus lower the reference potential;

[0048] The device also includes a control unit 15, of the microcontroller or microprocessor type, configured to control the Lithium charging circuit and / or the Lithium discharging circuit as well as the measurement of the voltage U1 and / or U2 by the measuring circuit 12+ and the measuring circuit 12-.

[0049] The measuring circuits 12+, 12-, the lithium discharge circuit 13+, the lithium charging circuit 13-, the reference circuit 13ref, and the control unit 15 can be integrated, partially or totally, into a battery management system, usually referred to as a BMS (Battery Management System). Alternatively, they can be formed from laboratory equipment. According to Another possibility is that all or part of the circuits mentioned above are integrated onto the battery, for example in a smart-cell (intelligent battery) type configuration.

[0050] The reference circuit 13ref allows the reference potential to be transferred to a buffer point 10'ref, or reference point, whose potential is the same as the reference potential. The buffer point 10'ref is connected to the voltage measurement circuit 12+ with respect to the positive electrode and / or to the voltage measurement circuit 12- with respect to the negative electrode. Transferring the reference potential to the buffer point prevents excessively rapid discharge of the reference electrode. The aim is to maintain the reference potential as stable as possible, without experiencing the significant variation that would occur if the reference electrode were directly connected to a measurement circuit, due to the low capacitance of the reference electrode, typically a few tens of mAh.

[0051] Thus, the reference circuit 13ref is a so-called high-impedance circuit, configured to shift the reference potential to the potential buffer point, minimizing any modification of the reference potential. However, if a period of use of several months, or even several years, is taken into account, the reference circuit exhibits leakage currents, usually referred to as leakage current or bias current. Leakage currents are likely to affect the reference potential of the reference electrode. However, leakage currents depend on the architecture of the reference circuit. They can be estimated a priori, which makes it possible to charge or discharge the reference electrode with lithium at regular intervals, using the lithium 13+ discharge circuit or the lithium 13- charging circuit.

[0052] The device may include either only the Lithium 13+ discharge circuit or only the Lithium 13- charging circuit. The combined presence of the Lithium 13+ discharge circuit and the Lithium 13- charging circuit is advantageous because it allows for finer adjustment of the reference potential. This is suitable, for example, for complex scenarios, such as when the characteristics of the measuring electronics are not fully known at the time of the initial design and are therefore likely to send or draw a leakage current to or from the reference electrode, thus requiring the ability to adjust the electrode's potential in both directions. When the device includes both the Lithium 13+ discharge circuit and the Lithium 13- charging circuit, the control unit 15 is configured so as not to activate the Lithium charging and discharge circuits simultaneously.

[0053] As described below, determining the potential of the negative electrode makes it possible to limit or prevent the formation of lithium plating at the negative electrode 10⁻. This involves, in particular, controlling the potential of the negative electrode at the end of charging, so that it does not fall below 0 V vs Li⁺ / Li. The notation vs Li⁷Li means that the potential is measured with respect to the lithium ion (Li⁺) / lithium metal (Li) redox couple.

[0054] Figure 4 schematically illustrates a first embodiment of the invention. The reference circuit 13ref consists of a switch SW3 and an operational amplifier A3, operating in a follower mode with negative feedback (negative input V3+ connected to the output) and unity gain. The switch SW3 is closed only during the measurement of the voltage between the potential buffer point 10'ref and the positive or negative electrode. The reference circuit 13ref may include a low-pass filter, here formed by a resistor R3 and a capacitor Cl connected to ground. The operational amplifier A3 is powered by a high supply and a low supply, the latter being ground.

[0055] With such an arrangement, at each closing of the SW3 switch, the leakage current is formed by a summation of the leakage currents resulting from the SW3 switch, the amplifier A3 and a possible analog-to-digital converter ADC, allowing a digitization of the reference potential.

[0056] During each measurement of the voltages Ui and U2, the switch SW3 is closed, being controlled by the control unit 15. The frequency of these measurements is determined on a case-by-case basis, depending on the accuracy with which one wishes to follow the evolution of the potential of the positive electrode or the negative electrode.

[0057] Control unit 15 is configured to: - determine the duration for which the reference electrode 10ref is connected to the reference circuit 13ref; - periodically activate the Lithium 13+ discharge circuit or the Lithium 13- charging circuit, so as to maintain the reference potential Uref at the predetermined reference value, based on a cumulative duration during which the reference electrode has been connected to the reference circuit 13ref

[0058] The Lithium 13+ discharge circuit includes a charge switch SW1 and a charge resistor RL. When the charge switch SW1 is closed, the discharge current 6 is established between the positive electrode 10+ and the reference electrode 10ref, so as to increase the electrical potential of the reference electrode 10ref. The charge switch SW1 is kept open outside of the Lithium discharge periods of the reference electrode 10ref.

[0059] The Lithium 13- charging circuit includes a discharge switch SW2 and a discharge resistor R2. When the discharge switch SW2 is closed, a discharge current L is established between the reference electrode 10ref and the negative electrode 10-, so as to decrease the electrical potential of the reference electrode 10ref.

[0060] In the configuration shown in [Fig. 4], the currents are respectively such that :

[0061] ; _ (3) and • _ £2 (4) '1 - W, *2 “ R:

[0062] The lithium charging and / or lithium discharging time is precisely determined by the control unit so that the reference potential corresponds to the predetermined reference value. Each lithium charging or discharging operation can be performed periodically, between regular time intervals, or when the switching time of the reference electrode with the reference circuit exceeds a predetermined threshold, beyond which the reference potential is considered to have to be returned to the reference value.

[0063] Figure 5 represents another, more sophisticated embodiment. The reference circuit 13ref is similar to that described in connection with Figure 4. The control unit 15 has the same functionalities as previously described, namely, controlling the reference circuit for measuring the voltages Ui or U2, as well as controlling the circuit Lithium charging and / or discharging circuit.

[0064] The Lithium 13+ discharge circuit includes a current sink, which emits a discharge current ib. In this example, the Lithium 13+ discharge circuit is formed by a negative feedback operational amplifier Al (negative input VI- connected to the amplifier output), whose positive input V1+ is connected to a charge control voltage V_DAC1. The output of Al is connected to the base of a bipolar load transistor Ql, of which: - the collector is connected to the positive electrode, via a first electrical discharge switch SW 1; - the transmitter is connected to the reference electrode, via a second electrical discharge switch SW2.

[0065] Switches SW1 and SW2 are closed simultaneously, only during the Lithium discharge of the reference electrode. Depending on the electrical discharge control voltage V_DAC1, the discharge current ii flows through the load transistor Ql, such that:

[0066] . vuAc-Unf / \ L “ J / /

[0067] Compared to the charging circuit described in connection with Figure 4, an advantage of the lithium discharge circuit shown in Figure 5 is that the discharge current p does not depend on the potential of the positive electrode 10+, but only on the potentials 10 and Vref. Since these are assumed to be constant, the discharge current h is constant and does not vary according to the state of charge SOC of the battery. This allows for better control of the lithium discharge of the reference electrode, resulting in a more precise adjustment of the reference potential to the predetermined reference value.

[0068] Symmetrically, the Lithium 13- charging circuit includes a current sink, which emits a discharge current i2. In this example, the Lithium 13- charging circuit is formed by a negative feedback operational amplifier A2 (negative input V2- connected to the amplifier output), and whose positive input V2+ is connected to a discharge control voltage V_DAC2. The output of A2 is connected to the base of a bipolar discharge transistor Q2, of which: - the collector is connected to the positive electrode, via a first electrical discharge switch SW 1 '; - the transmitter is connected to the reference electrode, via a second electrical discharge switch SW2'.

[0069] Switches SW1' and SW2' are closed simultaneously only during lithium charging of the reference electrode. Depending on the electrical discharge control voltage V_DAC2, the discharge current i2 flows through the discharge transistor Q2, such that:

[0070] . Vrel-VDAC2 (6) ^1- r2

[0071] As explained in relation to the lithium charging circuit, the discharge current i2 does not depend on the potential of the negative electrode 10-, but only on the potentials 2 and Uref. Since these are assumed to be constant, the discharge current i2 is constant and does not vary according to the state of charge SOC of the battery. This allows for better control of the lithium charging of the reference electrode, resulting in a more precise adjustment of the reference potential to the predetermined reference value.

[0072] An example of implementing a battery of the invention is now described. The aim is to prevent the potential of the negative electrode from falling below 0V (vs. Li7Li) during battery charging. Figure 6A schematically illustrates the evolution, as a function of time (abscissa axis), of the potentials U+ and U- of the positive and negative electrodes, respectively, during rapid charging, with and without implementation of the invention.

[0073] The invention makes it possible to precisely determine the potential U- of the negative electrode and to monitor its evolution over time. In Figure 6A, the curves U- (a) and U- (b) represent the evolution of the potential of the negative electrode respectively without and with implementation of the invention. As previously indicated, without implementation of the invention, the potential U- of the negative electrode, after a certain charging time At, may be less than 0V (vs Li+ / Li). This can promote the deposition of metallic lithium at the negative electrode. Implementation of the invention makes it possible to periodically measure, for example every minute, the potential U- of the negative electrode. This potential can be compared to a threshold Uth, the value of which is positive but low compared to 0V (vs Li+ / Li).

[0074] An interesting aspect of the invention is that the lithium charging and / or discharging of the reference electrode is carried out using the electrical potentials at the positive or negative electrode of the battery, without any energy input from an external source. This allows for local operation within the battery, or even the integration of some of the various components and functions within the battery itself. In particular, integrating the lithium charging and / or discharging circuits, control unit, and reference circuit within the battery makes it possible to have a battery that only exposes its positive and negative terminals and the potential buffer point to external measurements.

[0075] Figure 6B shows the evolution, as a function of time (abscissa axis), of the battery charging current / without implementing the invention (curve f^)) and with implementing the invention (curve / ( / >))•

[0076] As long as U- Uth, the intensity of the battery charging current takes a first value ^i, which corresponds to a maximum charging intensity.

[0077] When U- = Uth, the intensity of the battery charging current is decreased: the intensity of the charging current is equal to a second value with ! '< A- The slight increases in potential when U- is close to the threshold value are due to internal polarization and resistance effects of the electrodes.

[0078] Each time the threshold Uth is crossed, the battery charging current is reduced. Figures 6A and 6B show three periods Atb, At2, and At3 during which the charging current takes the values ​​I1, I2, and I3, respectively, with I2 < I1 and I3 < I2.

[0079] This allows the maximum SOC of the battery to be reached progressively, while maintaining, at the level of the negative electrode, a potential U. greater than 0V (vs Li+ / Li).

[0080] This also makes it possible to limit the potential of the positive electrode, in order to avoid, beyond a certain value, instability of the electrolyte or degradation of the crystal structure.

[0081] Figure 7 summarizes the main steps of a method implementing the invention. The control unit 15 is configured to: - Regularly order a measurement of the negative potential U- and / or the positive potential U+; step 100 - after a predetermined number of measurements, or after a predetermined duration of connection of the reference electrode to the reference circuit, maintain the reference potential at the predetermined value, by activating the Lithium charging circuit or the Lithium discharging circuit: step 110; - During battery charging, compare the negative (or positive) potential to a threshold value: step 120 - if the threshold value is exceeded, adjust the battery charging current intensity: step 130.

[0082] Although described in connection with a lithium-ion battery, the invention can be implemented with a metal-ion battery. In this case, the potential of the reference electrode is stabilized by charging or discharging metal ions, in the same way as previously described with lithium.

Claims

Demands

1. A metal-ion battery, comprising a negative electrode, a positive electrode, and an electrolyte, extending between the negative electrode (10-) and the positive electrode (10+), the negative electrode being configured to release, by oxidation, positive metal ions (Li+), during battery discharge, so that the positive metal ions migrate towards the positive electrode; accept, by reduction, positive ions during battery charging; the battery comprising a reference electrode (10ref), extending between the negative electrode and the positive electrode, brought to a reference potential, the reference electrode being connected to a measuring circuit (12-, 12+), configured to measure: a difference between a potential of the negative electrode and the reference potential; and / or a difference between a potential of the positive electrode and the reference potential; the battery containing or being connected to: a Lithium (13+) discharge circuit of the reference electrode, extending between the positive electrode and the reference electrode; and / or a Lithium (13-) charging circuit for the reference electrode, extending between the reference electrode and the negative electrode and; a control unit (15), configured to activate the Lithium charging circuit and / or the Lithium discharging circuit, so as to adjust the reference potential relative to a predetermined reference value; the battery being characterized in that it comprises or is connected to: a potential buffer value point ( 10'ref); a reference circuit (13ref), configured to be activated by the control unit, and to report the potential reference point on the potential buffer value point when activated; the battery being such that the measuring circuit (12-, 12+) extends between the potential buffer value point and the negative electrode and / or between the potential buffer value point and the positive electrode.

2. Battery according to claim 1, wherein: - the reference circuit includes a switch (SW3); - the control unit is configured to drive the switch, so as to allow a transfer of the reference potential to the potential buffer value point.

3. Battery according to any one of the preceding claims, wherein the control unit (15) is configured to activate the Lithium charging circuit or the Lithium discharging circuit of the reference electrode, depending on a duration for which the reference circuit has been activated.

4. Battery according to any one of the preceding claims, wherein the control unit is configured to: - store a leakage current resulting from each activation of the reference circuit; - activate the Lithium charging circuit and / or the Lithium discharging circuit of the reference electrode according to an accumulation of leakage currents during several successive activations of the reference circuit.

5. Battery according to any one of the preceding claims, wherein the control unit is configured to estimate the potential of the negative electrode and / or the potential of the positive electrode as a function of the potential difference measured by the measuring circuit.

6. Battery according to claim 5, wherein during battery charging, the control unit is configured to: - compare the potential of the negative electrode or the potential of the positive electrode to a predetermined threshold value; - adjust the intensity of a battery charging current according to the comparison.

7. Battery according to any one of the preceding claims, wherein the control unit is remote from the battery.

8. Battery according to any one of claims 1 to 6, wherein the control unit is integrated into the battery.

9. A method for controlling a battery according to any one of the preceding claims, the method comprising a periodic activation of the Lithium charging circuit or the Lithium discharging circuit of the reference electrode so as to adjust the potential of the reference electrode relative to a predetermined reference value.

10. A method according to claim 9, wherein the adjustment of the reference potential is carried out without connecting the reference electrode to an external energy source.

11. A method according to any one of claims 9 or 10, comprising: - periodic activation of the reference circuit, so as to shift the reference potential to the potential buffer point; - periodic measurement of a potential difference between the negative electrode and the potential buffer point and / or between the positive electrode and the potential buffer point; - periodic estimation of the potential of the negative electrode or the positive electrode as a function of the potential difference measurement.

12. A method according to claim 11, wherein the Lithium charging circuit or the Lithium discharging circuit of the reference electrode is activated according to a cumulative duration of successive activations of the reference circuit.

13. A method according to claim 12 or claim 11, comprising, during battery charging, in which the battery is supplied with a charging current: - measuring a potential difference between the positive electrode and the potential buffer point and / or between the negative electrode and the potential buffer point; - adapting the charging current according to the measured potential difference(s).

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