Method for controlling the generation of gas by a battery and associated control device

Abstract

The invention relates to a method for controlling the generation of gas by a battery, the method comprising the following steps: determining, at a given time te, an amount of gas Xte generated by the battery between a time t0 when the battery is brought into use and the time te as a function of a history of the operating conditions of the battery between t0 and te, estimating, on the basis of a prediction model, an amount of gas XtEOL generated by the battery at the end of life of the battery tEOL as a function of the amount of gas Xte and a history of the operating conditions of the battery between t0 and te, comparing the estimated amount of gas XtEOL with a predefined limit value L, and adjusting the battery operating conditions when the estimated amount of gas XtEOL is greater than or equal to the limit value L.

Description

Description Title of the invention: Method for controlling gas generation by a battery and associated control device

[0001] The present invention relates, in general, to the degassing of the cells of a battery, such as a Li-ion battery incorporating a nickel-rich lamellar oxide cathode active material (Ni).

[0002] In particular, the invention relates to the control of gas generation by a battery and especially by the cells it incorporates and, more specifically, a method of controlling gas generation by a battery, a device for controlling gas generation by a battery, as well as a motor vehicle incorporating such a control device.

[0003] Li-ion batteries that incorporate cathodes comprising Ni-rich lamellar oxide as the active material are particularly prone to gas generation, especially when high potentials (vs. Li / Li+) and high temperatures are reached.

[0004] However, gas production can be detrimental to battery performance. Gas accumulates in the pores of the electrode or between the electrode and the separator, increasing the internal resistance of the cell.

[0005] Furthermore, at a certain level of gas production, the pressure inside the cell can become high enough to rupture the cell in the case of so-called "pouch" cells, whose envelope forms a pocket, or to leak through the vent valve in the case of prismatic cells. These phenomena are referred to below as cell degassing.

[0006] During battery use, outgassing causes a drop in voltage in the affected cells. When this voltage drop is detected by a battery management system (BMS), it can lead to the battery shutting down.

[0007] Nevertheless, the battery can operate in a wide range of charge states and temperatures, without producing enough gas to cause outgassing of the cells.

[0008] The occurrence of cell outgassing is primarily determined by the state of charge and temperature (SOC - T°) conditions to which the battery is subjected during its lifetime.

[0009] Four main mechanisms allow us to understand gas generation within a cell incorporating a Ni-rich lamellar oxide cathode: the formation of the SEI layer for "solid-electrolyte interphase" and the presence of impurities, which are two minor factors, as well as two main factors which are the oxidation of the electrolyte and the chemical reaction with oxygen.

[0010] The invention therefore aims to remedy these drawbacks and to propose a strategy for predicting and controlling gas generation in a battery in order to reduce the risks of opening the cells that compose it.

[0011] A method for controlling gas generation by a battery is therefore proposed, comprising the following steps:

[0012] the determination, at a given time L, of a quantity of gas XL generated by the battery between a time to of battery commissioning and time L, as a function of a history of battery usage conditions between to and L,

[0013] the estimation, based on a predictive model, of the quantity of XIEOL gas generated by the battery at the end of the battery's life time t E0L, depending on the quantity of gas XL and the history of battery usage conditions between to and L,

[0014] the comparison of the quantity of gas Xt EO L estimated relative to a predefined limit value L, and

[0015] adjusting the battery usage conditions when the amount of gas Xt EOL is estimated to be greater than or equal to the limit value L.

[0016] Such a control process makes it possible to avoid battery failure by controlling the risk of cell outgassing.

[0017] The control method according to the invention is particularly advantageous for a Li-ion battery incorporating cathode materials used at high potentials, above 4.2V.

[0018] In one implementation mode, the adjustment can be performed iteratively and can include, at an iteration n where n is an integer greater than or equal to 1:

[0019] the application to the battery of a combination of state of charge and temperature conditions [SOC - T] n restrictive,

[0020] the estimation from the prediction model of a quantity of gas Xt EO L,[soc-T]n generated by the battery at the end-of-life time of the IEOL battery, as a function of the combination of state-of-charge and temperature conditions [SOC - T] n applied,

[0021] the comparison of the quantity of gas Xt EOL;[S oct] E estimated in relation to the predefined limit value L, and

[0022] the application of a new combination of state of charge and temperature conditions [SOC - T] n+ iplus restrictive than the combination of state of charge and temperature conditions [SOC - T] n previous until the quantity of gas X ffiOLi [soc-nn+iestimated to be lower than the limit value L.

[0023] In another implementation mode, the adjustment can be made using artificial intelligence trained to determine an optimal combination of restrictive usage conditions leading to a quantity of gas Xt Era generated by the battery at the end of the battery's life time t EOE lower than the limit value L, based on a database of historical battery usage conditions.

[0024] Preferably, the history of battery usage conditions between to and te includes the evolution of one or more battery parameters among: temperature, state of charge, current and voltage.

[0025] Advantageously, when the quantity of gas Xt EOE generated by the battery at the end of the battery's life t E0L is less than the limit value L, a new estimate of the quantity of gas Xt E0Egenerated by the battery at the end of the battery's life ÎEOL can be carried out later.

[0026] The invention also relates to a device for controlling gas generation by a battery, comprising:

[0027] a connection interface capable of plugging into the battery and communicating with it to collect data relating to battery usage conditions; and

[0028] a calculator capable of:

[0029] determine, at a given time L, a quantity of gas XL generated by the battery between a time L of battery commissioning and time L, based on a history of battery usage conditions between L and L,

[0030] estimate, using a predictive model, the quantity of gas Xt E0E generated by the battery at a battery end-of-life time t E0L, depending on the quantity of gas XL and the history of battery usage conditions between L and L,

[0031] compare the estimated XLOL gas quantity against a predefined limit value L, and

[0032] adjust the battery usage conditions when the amount of gas Xt EOL is estimated to be greater than or equal to the limit value L.

[0033] In one embodiment, the computer may be capable of performing the adjustment iteratively, the computer being capable of:

[0034] apply to the battery a combination of state of charge and temperature conditions [SOC - T] n restrictive,

[0035] estimate, using the prediction model, a quantity of gas Xt EOL ,[soc-T]n generated by the battery at the end-of-life time of the IEOL battery. depending on the combination of state-of-charge and temperature conditions [SOC - T] n applied,

[0036] compare the quantity of gas Xt EOL ,[soc - Tj n estimated in relation to the predefined limit value L, and

[0037] apply a new combination of state of charge and temperature conditions [SOC - T] n+ iplus restrictive than the combination of state-of-charge conditions and of temperature [SOC - T] n previous until the estimated quantity of gas XtEOL, [soc-Tjn+i is less than the limit value L.

[0038] In another embodiment, the computer may be able to adjust the battery usage conditions when the amount of gas Xt E The estimated ΔL is greater than or equal to the limit value L, using artificial intelligence trained to determine an optimal combination of restrictive usage conditions leading to a quantity of gas Xt E0L generated by the battery at the end of battery life time teoL less than the limit value L, based on a database of historical battery usage conditions.

[0039] Preferably, the connection interface is capable of collecting one or more data points chosen from: operating temperature, current, load state distribution.

[0040] The invention also relates to a motor vehicle comprising at least one device for controlling the generation of gas by a battery as previously described.

[0041] Other goals, advantages, and characteristics will become apparent from the following description, given for illustrative purposes only and with reference to the attached drawings, on which:

[0042] [Fig.1] illustrates a method of controlling the generation of gas by a battery according to an embodiment of the invention.

[0043] [Fig.2] is a logic diagram representing a method of controlling the generation of gas by a battery according to an embodiment of the invention.

[0044] In what follows, and unless otherwise indicated, the boundaries of a range of values ​​are included in that range, in particular in the expression "between".

[0045] Furthermore, the expression "at least one" used in this description is equivalent to the expression "one or more".

[0046] Figures 1 and 2 illustrate a control method according to the invention for controlling the production of gas resulting from the operation of a battery.

[0047] The battery can be any type of battery, for example a Li-ion battery, and intended for any type of use.

[0048] In one embodiment, the battery may be a battery comprising a cathode incorporating a Ni-based lamellar oxide active material, such as a Li-ion battery, particularly prone to gas generation, especially when used at potentials above 4.2 V.

[0049] By "Ni-based", we mean a material consisting mainly of Ni.

[0050] The battery includes, for example, a cathode incorporating an active material based on NMC, nickel manganese cobalt, such as NMC 622 or 811.

[0051] As an example, the battery can be a motor vehicle battery, such as an electric or hybrid motor vehicle, but is not limited to use in a motor vehicle.

[0052] The method for controlling gas generation by the battery includes a step 100 of determining, carried out at a time L during the life of the battery, a quantity of gas XL generated by at least one cell of the battery since its commissioning, i.e. between a time to of battery commissioning and time L-

[0053] Step 100 of determining the quantity of XL gas is carried out based on a history of battery usage conditions between tO and te.

[0054] Preferably, the history of battery usage conditions between L and L includes the history of the evolution of the battery temperature and its state of charge, known as "State Of Charge", SOC, in Anglo-Saxon terms.

[0055] The history of battery usage conditions between L and L may also include, for example, the evolution of battery current and voltage.

[0056] The amount of XL gas generated by the battery can thus be estimated from empirical or semi-empirical data.

[0057] The control process further includes a step 200 of estimating a quantity of gas Xt E0L generated by the battery at a battery end-of-life time t E0L .

[0058] Step 200 of estimating the quantity of gas Xt E0L is performed using a predictive model based on the previously determined quantity of gas XL and the history of battery usage conditions recorded between L and L-

[0059] By IEOL battery end of life, or "End Of Life" in Anglo-Saxon terms, we mean the moment when performance becomes insufficient for the use of the battery, and in particular when the outgassing of the battery leads to the opening of at least one of the cells that compose it.

[0060] Step 200 of estimating the quantity of gas Xt Era generated by the battery at the end of the battery's life time t E0 L can be achieved by the extrapolation prediction model based on the previously determined quantity of gas XL and the historical F of the battery usage conditions recorded between L and L-

[0061] The quantity of gas Xt E0L generated by the battery at the end of battery life tEOL is to be calculated in volume and / or mass, for example in mol.

[0062] Step 200 of estimating the quantity of gas XL generated by the battery at time L can, in addition, be carried out from physical parameters of the cells that make up the battery.

[0063] The quantity of gas XL generated by the battery at time L can thus be calculated from empirical or semi-empirical data.

[0064] The process of controlling the gas generation by the battery then includes a step of comparing the quantity of XIEOL gas obtained with a predefined limit value L.

[0065] Advantageously, the limit value L can be predefined based on one or more physical parameters of the battery cells, such as the cells' capacity to contain gas without outgassing. The battery cells can be pouch-shaped or prismatic.

[0066] When the quantity of gas X ffiO L is less than the limit value L generated by the battery at the end of battery life time t EnT No cell outgassing is planned before the end of the battery's lifespan. It is not necessary to limit the battery's operating conditions.

[0067] Preferably, when the quantity of gas Xt E0The L generated by the battery at the end of the IEOL battery life is less than the limit value L, a new estimate of the amount of gas Xt E0L generated by the battery at the end of the battery's life time t E0 L is carried out later, after some time, for example a few months later, based on a more complete history of battery use, in order to ensure that the amount of gas XæoL remains below L.

[0068] When the quantity of gas Xt E0L If the calculated value is greater than or equal to the predefined limit value L, there is a risk of the battery cell opening before the end of its service life. It is necessary to limit the battery's exposure to certain operating conditions. The battery's operating conditions are adjusted in an adjustment step 400 of the control process.

[0069] In a first implementation mode, the 400 adjustment is performed by iteration.

[0070] At iteration n, where n is an integer greater than or equal to 1, the adjustment step 400 includes the application of a combination of state of charge and temperature conditions [SOC - T] n restrictions on the battery.

[0071] In other words, at adjustment step 400, the state of charge and temperature conditions to which the battery is subjected are reduced by applying a combination of state of charge and temperature conditions [SOC - T] n .

[0072] Since gas production by battery cells is associated with the state of charge and temperature conditions to which the battery is subjected, reducing the state of charge and temperature of the battery helps to limit gas production by the battery cells.

[0073] The quantity of gas XtEO L,[soc-T]n generated by the battery at the end of battery life time IEOL is estimated from the prediction model, based on the combination of state of charge and temperature conditions [SOC - Not applied.

[0074] The quantity of gas Xt E oL,[soc-T] n The estimated value is compared to the predefined limit value L.

[0075] When the quantity of gas X ŒO L, [soc-Tj n is greater than or equal to the limit value L, a new combination of state of charge and temperature conditions [SOC - T] n+ iplus restrictive than the combination of state of charge and temperature conditions [SOC - T] n The previous one is applied.

[0076] In other words, the state of charge and temperature conditions to which the battery is subjected are further reduced by applying a new combination of state of charge and temperature conditions [SOC - T]n+ i.

[0077] The new quantity of gas X ffiOLj [soc-Tjn+iest then estimated on the basis of the new combination of state of charge and temperature conditions [SOC - T] n+i more restrictive applied.

[0078] The control of gas generation by the battery is thus carried out by successive approximations and a new combination of state of charge and temperature conditions more restrictive than the previous one is applied to the battery until the resulting estimated quantity of gas XæoL is less than the limit value L and the risk of opening the battery cells is eliminated.

[0079] Advantageously, the control process can include a step of applying a previous combination of state-of-charge and temperature conditions [SOC - Restrictive indicators that the combination of state of charge and temperature conditions [SOC - T] nThe previous combination is applied when the old one is so effective that the risk of outgassing has been sufficiently eliminated. The battery user can then recover increased performance.

[0080] This step of reducing the limitation can also be performed iteratively until the combination of state-of-charge and temperature conditions [SOC] - T] n .it is less restrictive but still allows the limit value L to remain below the applied limit value.

[0081] In a second implementation mode, the adjustment step 400 can be performed using artificial intelligence.

[0082] Artificial intelligence is trained to determine, in a single step, without iteration, an optimal combination of restrictive operating conditions, including temperature and state of charge [SOC - T], leading to a quantity of gas Xt EOL generated by the battery over the battery's lifetime t EOL lower than the limit value L.

[0083] The determination of the optimal combination by artificial intelligence relies on the use of a historical database of usage conditions of previously used batteries, reflecting the habits of former users of similar batteries, and whose usage conditions have been recorded in the database.

[0084] When restrictive battery temperature conditions must be applied, the temperature can be reduced by controlling a battery cooling system and / or by limiting its performance.

[0085] Furthermore, the state of charge can be limited by blocking battery charging at a predetermined maximum threshold value.

[0086] Advantageously, the control method according to the invention can be implemented within a gas generation control device by a battery, incorporating all the hardware and software means for the implementation of this control method.

[0087] The control device includes a connection interface capable of connecting to the battery and communicating with it to collect data relating to the battery's usage conditions.

[0088] In addition, the control system includes a computer capable of:

[0089] to determine, at a given time L, a quantity of gas XL generated by the battery between a time to of battery commissioning and time te, as a function of a history of battery usage conditions between to and L,

[0090] estimate, using a predictive model, the quantity of gas Xt B0The energy generated by the battery at the end of the battery's life is t B0L , depending on the quantity of XL gas and the history of battery usage conditions between L and L,

[0091] compare the estimated quantity of XÎEOL gas against a predefined limit value L, and

[0092] adjust the battery usage conditions when the amount of gas Xt EOL is estimated to be greater than or equal to the limit value L.

[0093] The connection interface can advantageously be capable of collecting one or more data chosen from: the battery operating temperature, the current, the state of charge distribution.

[0094] The computer incorporating the prediction model can be a specific computer or can be integrated into a battery management system, BMS, such as the BMS of a motor vehicle.

[0095] In one embodiment, the computer may be capable of performing the adjustment iteratively, the computer thus being capable of:

[0096] apply to the battery a combination of state of charge and temperature conditions [SOC - T] n restrictive,

[0097] estimate, using the prediction model, a quantity of gas Xt EO L,[soc-T]n generated by the battery at the end of the battery's life time t EOL , depending on the combination of state of charge and temperature conditions [SOC - T] n applied,

[0098] compare the quantity of gas Xt EOL ,[soc - TinCstimed with respect to the predefined limit value L, and

[0099] apply a new combination of state of charge and temperature conditions [SOC - T] n+ iplus restrictive than the combination of state of charge and temperature conditions [SOC - T] nprevious until the estimated quantity of gas XæoL, isoc-nn+i is less than the limit value L.

[0100] Advantageously, the control device may be able to apply a former combination of state of charge and temperature conditions [SOC - Indicators restrictive than the combination of state of charge and temperature conditions [SOC - T] n previous applied when the old combination is so effective that the risk of outgassing has been sufficiently eliminated.

[0101] The control device may be capable of applying this old combination of state of charge and temperature conditions [SOC - T] n .i per iteration.

[0102] In an alternative embodiment, the computer may be able to adjust the battery usage conditions when the amount of gas Xt E0L estimated is greater than or equal to the limit value L using embedded artificial intelligence.

[0103] Artificial intelligence can be trained to determine an optimal combination of restrictive usage conditions leading to a quantity of gas Xt EO L generated by the battery at the end of the battery's life t EOL lower than the limit value L, based on a database of historical battery usage conditions.

[0104] Preferably, when the quantity of gas Xt E0L If the amount of gas XtsoL generated by the battery at the end of its life is less than the limit value L, the control device is capable of subsequently performing a new estimation of the amount of gas XtsoL generated by the battery at the end of its life. EO L-

[0105] The new estimate can be made at regular intervals, for example every month, as long as the limit value L is not reached.

Claims

Demands

1. A method for controlling gas generation by a battery, comprising the following steps: determining, at a given time, the quantity of gas Xte generated by the battery between a time to of battery commissioning and time te, based on a history of battery usage conditions between to and te; and estimating, from a predictive model, the quantity of gas XIEOL generated by the battery at a battery end-of-life time t. E0L , depending on the amount of gas Xte and the history of battery usage conditions between to and te, the comparison of the estimated amount of gas XIEOL against a predefined limit value L, and the adjustment of battery usage conditions when the estimated amount of gas XIEOL is greater than or equal to the limit value L.

2. A method according to claim 1, wherein the adjustment is made iteratively and comprises at an iteration n where n is an integer greater than or equal to 1: the application to the battery of a combination of state of charge and temperature conditions [SOC - T] n restrictive, the estimation from the prediction model of a quantity of gas XtEOL,[soc-nn generated by the battery at the end of battery life time t E0L , depending on the combination of state of charge and temperature conditions [SOC - T] n applied, the comparison of the estimated quantity of gas XtEOLjsoc-nn with the predefined limit value L, and the application of a new combination of state of charge and temperature conditions [SOC - T] n+ iplus restrictive than the combination of state of charge and temperature conditions [SOC - T] n previous until the quantity of gas X tPnT , [S0C-T]n+iestimated is less than the limit value L.

3. A method according to claim 1, wherein the adjustment is made using artificial intelligence trained to determine an optimal combination of restrictive operating conditions leading to a quantity of gas Xt E0L generated by the battery at the end of battery life time "less than the limit value L, based on a database of historical battery usage conditions.

4. A method according to any one of the preceding claims, wherein the history of the battery usage conditions between to and te includes the evolution of one or more battery parameters among: temperature, state of charge, current and voltage.

5. A method according to any one of the preceding claims, wherein when the quantity of gas Xt EoL generated by the battery at the end of the battery's life time t E 0L is below the limit value L, a new estimate of the quantity of gas Xt E0 The energy generated by the battery at the end of the battery's life (tæL) is realized later.

6. A device for controlling gas generation by a battery, comprising: a connection interface capable of connecting to and communicating with the battery to collect data relating to battery usage conditions; and a computer capable of: determining, at a given time te, a quantity of gas Xte generated by the battery between a time to of battery commissioning and time te, based on a history of battery usage conditions between to and te; estimating, using a predictive model, a quantity of gas XtBOL generated by the battery at an end-of-life time tEOL, based on the quantity of gas Xte and the history of battery usage conditions between to and te; and comparing the quantity of gas Xt EOEestimated against a predefined limit value L, and adjust the battery usage conditions when the estimated XtsoL gas quantity is greater than or equal to the limit value L.

7. Device according to claim 6, wherein the computer is capable of performing the adjustment by iteration, the computer being capable of: applying to the battery a combination of state of charge and temperature conditions [SOC - T] n restrictive, estimate from the prediction model of a quantity of gas Xt^L, [soc-Tjn generated by the battery at the end of battery life IEOL. as a function of the combination of state of charge and temperature conditions [SOC - Not applied, compare the quantity of gas XtEOL,[soc-T] n estimated relative to the predefined limit value L, and apply a new combination of state of charge and temperature conditions [SOC - T] n+imore restrictive than the combination of state of charge and temperature conditions [SOC - T] n previous until the quantity of gas XtEo L , [soc-T]n+iestimated is less than the limit value L.

8. A device according to claim 6, wherein the computer is capable of adjusting the battery usage conditions when the estimated XtROL gas quantity is greater than or equal to the limit value L, using artificial intelligence trained to determine an optimal combination of restrictive usage conditions leading to a gas quantity Xt E0L generated by the battery at the end-of-life time of the battery tgoL less than the limit value L, based on a database of historical battery usage conditions.

9. Device according to any one of claims 6 to 8, wherein the connection interface is capable of collecting one or more data selected from: operating temperature, current, load state distribution.

10. Motor vehicle comprising at least one device for controlling the generation of gas by a battery according to any one of claims 6 to 9.

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