Electrode-based charge control of vehicle battery pack

Abstract

A method of controlling battery pack charging to minimize or avoid lithium plating is disclosed. The method may include charging the battery pack with a first charging current having a first charging profile, monitoring charging of the battery pack with the first charging current, and thereafter charging the battery pack with a second charging current having a cathode charging profile to prevent a cathode potential of the battery pack from exceeding a cathode threshold.

Description

Technical Field

[0001] The present disclosure relates to minimizing or avoiding plating when charging a battery pack, such as, but not necessarily limited to, minimizing or avoiding lithium plating when fast charging a lithium battery pack of the type configured to power an electric motor used to propel a vehicle. Background Art

[0002] Although the present disclosure is not limited to lithium, lithium ion or other lithium-based batteries, lithium batteries can be considered to be representative of a variety of batteries that are susceptible to plating, and in the case of lithium batteries, plating can be referred to as lithium plating. It will be appreciated by those skilled in the art that the sustained capacity of a lithium battery, particularly during a large number of repeated charge-discharge cycles, may depend to a large extent on the materials at which lithium is effectively moved into and out of the relative anode and cathode electrodes. During battery charging, not all lithium that enters the host material can adapt to a suitable intercalation form (e.g., LiC6 intercalation form for a host material comprising graphite), so that lithium plating may occur. When conditions cause lithium ion reduction to take precedence over lithium intercalation, plating may be produced by lithium ions (e.g., Li+) deposited as metallic lithium. At high charging currents, such as those typically used to charge batteries included in vehicles, for example, the Li+ ion transfer rate may exceed the rate at which Li+ ions can be embedded in the host material. This problem may be particularly evident during high current fast charging, low ambient temperature charging, and slow lithium ion movement and regenerative braking of the vehicle. Since the function of plated lithium metal may be different from that of intercalated lithium, lithium plating may limit the performance of the battery and restrict its use. Summary of the invention

[0003] One non-limiting aspect of the present disclosure relates to minimizing or avoiding plating when charging a battery pack, such as, but not necessarily limited to, minimizing or avoiding lithium plating when fast charging a lithium battery pack of the type configured to power an electric motor for propelling a vehicle. Contemplated prevention of plating can be achieved by selectively adjusting the charging current to avoid exceeding undesirable voltage potentials at the cathode and / or anode of the battery pack that could result in plating.

[0004] One non-limiting aspect of the present disclosure relates to a method for minimizing or avoiding lithium plating when performing direct current (DC) fast charging of a battery pack included in a vehicle. The method may include charging the battery pack with a first charging current having a first charging curve during a first charging phase, and thereafter starting a second charging phase of charging the battery pack with a second charging current having a cathode charging curve. The cathode charging curve may gradually decay the second charging current to prevent the cathode potential of the cathode of the battery pack from exceeding a cathode threshold.

[0005] The method may include starting a third charging phase of charging the battery pack using a third charging current having an anode charging curve. The anode charging curve may gradually decay the third charging current to prevent an anode potential of an anode of the battery pack from exceeding an anode threshold.

[0006] The method may include initiating a second charging phase after the first charging phase and before the third charging phase.

[0007] The method may include a first charging curve that uniformly maintains a first charging current in a non-decaying manner, a cathode charging curve that gradually decays a second charging current at a first decay rate, and an anode charging curve that gradually decays a third charging current at a second decay rate that is greater than the first decay rate.

[0008] The method may include starting a second charging phase after the first charging phase and after the third charging phase.

[0009] The method may include a first charging curve that uniformly maintains a first charging current in a non-decaying manner, an anode charging curve that gradually decays a second charging current at a first decay rate, and a cathode charging curve that gradually decays a third charging current at a second decay rate that is greater than the first decay rate.

[0010] The method may include monitoring the cathode potential and initiating a second charging phase in response to the cathode potential being within a predetermined cathode range of a cathode threshold.

[0011] The method may include monitoring the anode potential and initiating a third charging phase in response to the anode potential being within a predetermined anode range of an anode threshold.

[0012] The method may include monitoring a state of charge (SOC) of the battery pack and initiating a second charging phase in response to the SOC exceeding a cathode SOC threshold.

[0013] The method may include monitoring a state of charge (SOC) of the battery pack and initiating a third charging phase in response to the SOC exceeding an anode SOC threshold.

[0014] One non-limiting aspect of the present disclosure relates to a method for minimizing or avoiding lithium plating when direct current (DC) fast charging a battery pack included in a vehicle. The method may include charging the battery pack with a first charging current having a first charging curve during a first charging phase, monitoring a cathode potential of a cathode of the battery pack during the first charging phase, and starting a second charging phase of charging the battery pack with a second charging current having a cathode charging curve in response to the cathode potential approaching a cathode threshold. The cathode charging curve may include adjusting the second charging current relative to the first charging current to prevent the cathode potential from exceeding the cathode threshold.

[0015] The method may include the cathode charging profile decaying the second charging current according to a cathode step function, optionally the cathode step function being defined relative to a voltage of the battery pack.

[0016] The method may comprise a cathode step function comprising a plurality of step downs defined relative to a plurality of voltage values ​​for measuring the voltage, optionally each step down progressively reducing the second charging current relative to each step down defined relative to a greater one of the SOC values.

[0017] The method may include a first charging profile having a non-decay configuration and a cathode charging profile having a decay configuration.

[0018] One non-limiting aspect of the present disclosure relates to a system for minimizing or avoiding lithium plating when direct current (DC) fast charging a battery pack included in a vehicle. The system may include a battery pack monitor and a battery pack charger configured to monitor the battery pack voltage. The battery pack charger may be configured to charge the battery pack with a first charging current having a first charging curve during a first charging phase, and to start a second charging phase of charging the battery pack with a second charging current having a cathode charging curve in response to the voltage exceeding a first voltage threshold. The cathode charging curve may include adjusting the second charging current relative to the first charging current to prevent the cathode potential of the cathode of the battery pack from exceeding the cathode threshold.

[0019] The battery charger may be configured to initiate a third charging phase of charging the battery using a third charging current having a combined cathode-anode charging curve in response to the voltage exceeding a second voltage threshold that is greater than the first voltage threshold. The combined cathode-anode charging curve may include decaying the third charging current relative to the second charging current to prevent the cathode potential from exceeding a cathode charging threshold and to prevent the anode potential of the anode of the battery from exceeding an anode charging threshold.

[0020] The cathode charging profile may be configured to decay the second charging current according to a cathode step function. The cathode step function may include a plurality of step decreases defined relative to a plurality of voltage values ​​for measuring the voltage, optionally each step decrease progressively decreasing the second charging current relative to each step decrease defined relative to a larger one of the voltage values.

[0021] The first charging curve may include a non-decay configuration and the cathode charging curve may have a gradual decay configuration.

[0022] The present invention discloses the following technical solutions.

[0023] A method for minimizing or avoiding lithium plating when performing direct current (DC) fast charging of a battery pack included in a vehicle, comprising:

[0024] charging the battery pack during a first charging phase using a first charging current having a first charging profile; and

[0025] A second charging phase is initiated to charge the battery pack using a second charging current having a cathode charging profile that gradually decays the second charging current to prevent a cathode potential of a cathode of the battery pack from exceeding a cathode threshold.

[0026] Solution 2. The method according to solution 1, further comprising:

[0027] A third charging phase is initiated in which the battery is charged with a third charging current having an anode charging curve that gradually decays the third charging current to prevent an anode potential of an anode of the battery from exceeding an anode threshold.

[0028] Solution 3. The method according to Solution 2, further comprising:

[0029] The second charging phase begins after the first charging phase and before the third charging phase.

[0030] Solution 4. The method according to Solution 3, further comprising:

[0031] The first charging curve consistently maintains a first charging current in a non-decaying manner;

[0032] The cathode charging curve gradually decays the second charging current at a first decay rate; and

[0033] The anode charging curve gradually decays the third charging current at a second decay rate greater than the first decay rate.

[0034] Solution 5. The method according to Solution 2, further comprising:

[0035] After the first charging phase and after the third charging phase, a second charging phase begins.

[0036] Solution 6. The method according to Solution 5, further comprising:

[0037] The first charging curve consistently maintains a first charging current in a non-decaying manner;

[0038] The anode charging curve gradually decays the second charging current at a first decay rate; and

[0039] The cathode charging curve gradually decays the third charging current at a second decay rate greater than the first decay rate.

[0040] Solution 7. The method according to Solution 2, further comprising:

[0041] monitoring the cathode potential; and

[0042] A second charging phase is initiated in response to the cathode potential being within a predetermined cathode range of the cathode threshold.

[0043] Solution 8. The method according to Solution 7, further comprising:

[0044] monitoring the anode potential; and

[0045] A third charging phase is initiated in response to the anode potential being within a predetermined anode range of the anode threshold.

[0046] Solution 9. The method according to Solution 2, further comprising:

[0047] Monitor the state of charge (SOC) of the battery pack; and

[0048] A second charging phase is initiated in response to the SOC exceeding the cathode SOC threshold.

[0049] Solution 10. The method according to Solution 9, further comprising:

[0050] Monitor the state of charge (SOC) of the battery pack; and

[0051] A third charging phase is initiated in response to the SOC exceeding the anode SOC threshold.

[0052] Embodiment 11. A method for minimizing or avoiding lithium plating when performing direct current (DC) fast charging of a battery pack included in a vehicle, comprising:

[0053] charging the battery pack during a first charging phase using a first charging current having a first charging curve;

[0054] monitoring a cathode potential of a cathode of the battery during a first charging stage; and

[0055] In response to the cathode potential approaching the cathode threshold, a second charging phase of charging the battery pack is initiated using a second charging current having a cathode charging profile that adjusts the second charging current relative to the first charging current to prevent the cathode potential from exceeding the cathode threshold.

[0056] Solution 12. The method according to solution 11, further comprising:

[0057] The cathode charging profile decays the second charging current according to a cathode step function that is defined relative to a state of charge (SOC) of the battery pack.

[0058] Solution 13. The method according to Solution 12, further comprising:

[0059] The cathode step function includes a plurality of step decreases defined relative to a plurality of SOC values ​​for measuring the SOC, each step decrease gradually decreasing the second charging current relative to each step decrease defined relative to a larger one of the SOC values.

[0060] Solution 14. The method according to solution 11, further comprising:

[0061] The cathode charging profile decays the second charging current according to a cathode step function defined relative to a plurality of cathode potential values ​​used to measure the cathode potential.

[0062] Embodiment 15. The method according to embodiment 14, further comprising:

[0063] The cathode step function includes a plurality of step decreases defined relative to cathode potential values, each step decrease gradually decreasing the second charging current relative to each step decrease defined relative to a larger one of the cathode potential values.

[0064] Solution 16. The method according to solution 11, further comprising:

[0065] a first charging curve having a non-decay configuration; and

[0066] Cathodic charging curve with decay configuration.

[0067] Embodiment 17. A system for minimizing or avoiding lithium plating when performing direct current (DC) fast charging of a battery pack included in a vehicle, comprising:

[0068] a battery pack monitor configured to monitor a voltage of the battery pack; and

[0069] A battery pack charger configured for

[0070] charging the battery pack during a first charging phase using a first charging current having a first charging profile; and

[0071] In response to the voltage exceeding the first voltage threshold, a second charging phase of charging the battery pack is initiated using a second charging current having a cathode charging curve that adjusts the second charging current relative to the first charging current to prevent a cathode potential of a cathode of the battery pack from exceeding the cathode threshold.

[0072] Embodiment 18. The system according to embodiment 17, wherein:

[0073] The battery pack charger is also configured to initiate a third charging phase of charging the battery pack in response to the voltage exceeding a second voltage threshold that is greater than the first voltage threshold, using a third charging current having a combined cathode-anode charging curve that attenuates the third charging current relative to the second charging current to prevent the cathode potential from exceeding the cathode charging threshold and to prevent the anode potential of the anode of the battery pack from exceeding the anode charging threshold.

[0074] Embodiment 19. The system according to embodiment 17, wherein:

[0075] The cathode charging profile is configured to decay the second charging current according to a cathode step function, the cathode step function comprising a plurality of step decreases defined relative to a plurality of voltage values ​​for measuring the voltage, each step decrease gradually decreasing the second charging current relative to each step decrease defined relative to a larger one of the voltage values.

[0076] Embodiment 20. The system according to embodiment 17, wherein:

[0077] The first charging curve has a non-decay configuration; and

[0078] The cathode charging curve has a gradually decaying configuration.

[0079] These features and advantages and other features and advantages of the present teaching are apparent from the following detailed description of the mode for carrying out the present teaching when combined with the accompanying drawings. It should be understood that although the following drawings and embodiments may be described separately, their individual features may be combined in other embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0081] Figure 1 A battery pack according to one non-limiting aspect of the present disclosure is shown.

[0082] Figure 2 A schematic diagram of an electric vehicle is shown in accordance with one non-limiting aspect of the present disclosure.

[0083] Figure 3 A constant cathode potential method for minimizing or avoiding battery pack plating is shown in accordance with one non-limiting aspect of the present disclosure.

[0084] Figure 4 A constant cathode potential charging curve is shown in accordance with one non-limiting aspect of the present disclosure.

[0085] Figure 5A cathode step function according to one non-limiting aspect of the present disclosure is shown.

[0086] Figure 6 A combined constant potential approach for minimizing or avoiding battery pack plating according to one non-limiting aspect of the present disclosure is shown.

[0087] Figure 7 A constant anode-cathode potential charging curve is shown in accordance with one non-limiting aspect of the present disclosure.

[0088] Figure 8 An anode-cathode charging current curve is shown in accordance with one non-limiting aspect of the present disclosure.

[0089] Fig. 9 A cathode-anode potential charging curve is shown according to one non-limiting aspect of the present disclosure.

[0090] Fig.10 A cathode-anode charging current curve is shown according to one non-limiting aspect of the present disclosure. DETAILED DESCRIPTION

[0091] As required, detailed embodiments of the present invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely examples of the present disclosure that can be implemented in various and alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art to adopt the present disclosure in different ways.

[0092] Figure 1A battery 10 according to one non-limiting aspect of the present disclosure is shown. Although the present disclosure is not limited to lithium, lithium ion or other lithium-based batteries, the battery 10 may be primarily described as a lithium-type battery in order to represent various batteries susceptible to plating, which may be referred to as lithium plating in the case of a lithium battery. The battery may include a negative electrode or anode 12, a positive electrode or cathode 14, an electrolyte 16 operably disposed between the anode 12 and the cathode 14, and a separator 22. The anode 12, the cathode 14 and the electrolyte 16 may be encapsulated in a container 20, which may be, for example, a hard (e.g., metal) box or a soft (e.g., polymer) bag. The anode 12 and the cathode 14 may be located on opposite sides of the separator 22. The separator 22 may include a microporous polymer or other suitable material capable of conducting lithium ions and an optional electrolyte (i.e., a liquid electrolyte). For example, the electrolyte may include a polymer or a liquid electrolyte solution. The liquid electrolyte 16 may include LiPF6, LiBF4, and LiClO4 dissolved in a non-aqueous solvent, etc. The polymer electrolyte 16 may include one or more polymers, such as polyethylene oxide (PEO) or polyacrylonitrile, and one or more lithium salts, such as LiPF6, LiBF4, LiClO4, LiSICON or LiPON. The anode 12 may include a current collector 26 and a lithium intercalation host material 28 applied thereto. The cathode 14 may include a current collector 30 and a lithium-based active material 32 applied thereto. In one example, the anode 12 may include lithium and the cathode 14 may include sulfur. The active material 32 can store lithium ions at a higher potential than the intercalation host material 28. The current collectors 26 and 30 associated with the two electrodes 12, 14 can be electrically connected by an external circuit A (e.g., an interruptible circuit), which allows current to pass between the electrodes 12, 14 to electrically balance the associated migration of lithium ions. For clarity, although Figure 1 Host material 28 and active material 32 are schematically shown and may comprise dedicated interfaces between anode 12 and cathode 14 , respectively, and electrolyte 16 .

[0093] The main body material 28 may include any lithium main body material that can fully undergo lithium ion insertion, extraction and alloying while serving as the negative terminal of the lithium ion battery 10. The main body material 28 may also include a polymer binder material to structurally hold the lithium main body material together. For example, in one embodiment, the main body material 28 may include graphite mixed in one or more of polyvinylidene fluoride (PVdF), ethylene propylene diene monomer (EPDM) rubber, carboxymethyl cellulose (CMC) and styrene 1,3-butadiene polymer (SBR). Graphite and carbon materials can be widely used to form negative electrodes because they can exhibit favorable lithium ion insertion and extraction characteristics, relative non-reactivity, and can store lithium ions that produce a relatively high energy density. Other materials can also be used to form the main body material 28, such as one or more of lithium titanate, silicon, silicon oxide, tin and tin oxide. The anode current collector 26 may include copper, aluminum, stainless steel or any other suitable conductive material known to those skilled in the art. The anode current collector 26 may be treated (eg, coated) with a highly conductive material including one or more of conductive carbon black, graphite, carbon nanotubes, carbon nanofibers, graphene, vapor grown carbon fibers (VGCF), and the like.

[0094] The active material 32 may include any lithium-based active material that can fully undergo lithium insertion and extraction while serving as the positive terminal of the battery pack 10. The active material 32 may also include a polymer binder material to structurally hold the lithium-based active material together. A common class of known materials that can be used to form the active material 32 is a layered lithium transition metal oxide. For example, in various embodiments, the active material 32 may include spinel lithium manganese oxide (LiMn2O4), lithium cobalt oxide (LiCoO2), nickel-manganese-cobalt oxide [Li(NixMnyCoz)O2] or lithium iron polyanion oxide, such as one or more of lithium iron phosphate (LiFePO4) or lithium iron fluorophosphate (Li2FePO4F), which is mixed in at least one of polyvinylidene fluoride (PVdF), ethylene propylene diene monomer (EPDM) rubber, carboxymethyl cellulose (CMC) and styrene 1,3-butadiene polymer (SBR). In addition to those just mentioned, other lithium-based active materials can also be used. These alternative materials may include, but are not limited to, lithium nickel oxide (LiNiO2), lithium aluminum manganese oxide (LixAlyMn1-yO2), and lithium vanadium oxide (LiV2O5), to name a few. The cathode current collector 30 may comprise aluminum or any other suitable conductive material known to those skilled in the art, and may be formed into a foil or grid shape. The cathode current collector 30 may be treated (e.g., coated) with a highly conductive material, including one or more of conductive carbon black, graphite, carbon nanotubes, carbon nanofibers, graphene, and vapor-grown carbon fibers (VGCF).

[0095] For non-limiting purposes, the lithium-ion battery pack 10 is shown in singular form because the present disclosure fully contemplates that the battery pack 10 includes multiple additional battery packs, such as in a battery pack module or battery pack or other parts of a rechargeable energy storage system (RESS). The battery pack 10 can be connected in series and / or in parallel with the additional battery packs, and the corresponding battery packs are optionally configured to reversibly supply power and energy to the associated load device. Such lithium-ion battery packs 10 can also be used in various consumer electronic devices (such as laptops, cameras and cellular / smart phones), military electronic devices (such as radios, mine detectors and thermal weapons), aircraft and satellites, etc. Similarly, lithium-ion battery packs, modules and battery packs 10 can be incorporated into vehicles, such as hybrid electric vehicles (HEVs), battery electric vehicles (BEVs), plug-in HEVs or extended-range electric vehicles (EREVs) to generate sufficient power and energy to operate one or more systems of the vehicle. For example, the battery pack 10 , modules and battery packs may be used in combination with a gasoline or diesel internal combustion engine to propel a vehicle (such as in a hybrid vehicle), or may be used alone to propel a vehicle (such as in a battery-powered vehicle).

[0096] Figure 2 A schematic diagram of an electric vehicle 40 according to one non-limiting aspect of the present disclosure is shown. The vehicle 40 may include a battery pack 42 and related components, including a plurality of battery packs 10. The battery pack 42 may provide energy to a traction inverter 44, which converts the direct current (DC) battery pack voltage into a three-phase alternating current (AC) signal, which is used by an electric drive motor 46 to propel the vehicle 40. Optionally, an engine 48 may be included to drive a generator 50, which in turn may provide energy to recharge the battery pack 42 through the inverter 44. External (e.g., grid) power may also be used to recharge the battery pack 42 via an additional circuit (not shown). For example, the engine 48 may include a gasoline or diesel engine. The battery pack 10 may operate by reversibly passing lithium ions between the anode 12 and the cathode 14. When charging, lithium ions may move from the cathode 14 to the anode 12, and when discharging, lithium ions may move from the anode 12 to the cathode 14. The vehicle 40 may include a battery monitor 54 configured to monitor the battery pack 42 and / or the individual battery packs 10 therein and a battery charger 56 configured to control the charging and discharging thereof, which may be included as a battery monitoring system (BMS) or as part of a battery monitoring system or other type of battery control structure.

[0097] As described above, the present disclosure contemplates minimizing or avoiding plating of various battery packs, including but not necessarily limited to lithium-type battery packs. Plating may generally correspond to accumulation, metal deposition, coating, layering, or processing, whereby additives may be plated, bonded, attached, etc. to one or both of the anode 12 and the cathode 14, and in some cases more specifically to the current collectors 26, 30, the host material 28 associated therewith, and / or the active material 32. Therefore, the lithium plating primarily used herein is not intended to be limiting, but rather fully encompasses a variety of plating that can be minimized or avoided according to the methods, processes, systems, etc. described herein. To this end, Figure 3 A constant cathode potential method 60 for minimizing or avoiding battery pack plating according to one non-limiting aspect of the present disclosure is shown. The method 60 can be used to minimize or avoid the above-mentioned lithium plating of the cathode 14. As described in more detail below, the method 60 can help prevent lithium plating by selectively controlling the charging of the battery pack relative to the plating-related parameters determined for the cathode 14.

[0098] The constant cathode potential method 60 can be configured to minimize or avoid lithium plating of the battery 10 by adjusting the charging of the battery 10 according to the plating characteristics derived based on the properties of the cathode 14. In the case where the anode 12 is unlikely to plate lithium without adjusting the charging current due to the anode 12 having properties that can limit lithium plating, the constant cathode potential method can be beneficial to avoid or prevent lithium plating, for example, the anode or the current collector 26 and / or the host material 28 associated therewith can be robustly manufactured so that its lithium plating can be relatively insignificant under relevant or normal charging conditions. For example, the present disclosure contemplates the use of advances in the construction, manufacture, etc. of the anode (e.g., the above-mentioned anode 12), whereby the lithium plating of the anode may be relatively insignificant compared to the potential of the lithium plating of the cathode 14, or the current collector 30, or the active material 32 associated therewith. In other words, the advancement of the construction of the anode 12 can result in the lithium plating of the cathode 14 being more relevant to maintaining the desired operability of the battery 10 than the lithium plating potential of the anode 12, that is, the cathode 14 can be more susceptible to the influence of lithium plating.

[0099] Block 62 relates to an initial charging process for beginning charging of the battery pack 10 in what may be referred to as a first charging phase, which may include providing power to the battery pack 10 from the generator 50, another source onboard the vehicle 40, and / or a source external to the vehicle 40, such as another vehicle or a charging station. The first charging phase may correspond to the battery pack charger 56 determining a constant cathode potential charging curve 64 for the battery pack 10. Figure 4Such a constant cathode potential charging curve 64 is shown according to one non-limiting aspect of the present disclosure. The constant cathode potential charging curve 64 can be determined based on the operating characteristics of the cathode 14, empirical testing, monitoring of the battery pack over time, etc. The constant cathode potential charging curve 64 can be graphically represented relative to a cathode threshold 66 and a battery pack charging current 68 (each of which is defined relative to the state of charge (SOC) of the battery pack 10). The cathode threshold 66 can be selected based on the properties of the cathode 14 related to lithium plating to represent the maximum voltage potential required for the cathode 14 during charging. If the battery pack 10 is charged for an unexpected period of time in a manner that causes charging to occur when the cathode voltage potential is above the cathode threshold, the cathode 14 may potentially experience lithium plating. A vertical axis 70 depicting the voltage of the charging threshold is shown, but no individual voltage values ​​are shown because the accompanying values ​​vary widely depending on the type of cathode 14.

[0100] The battery pack charging current 68 may represent the current provided to the battery pack 10 for charging. The battery pack charging current 68 may include a first charging curve 72 associated with the current provided to the battery pack 10 before the cathode voltage potential approaches the cathode threshold 66 and a second charging curve 74 associated with the current provided to the battery pack 10 thereafter, wherein the second charging curve 74 is optionally configured to prevent the cathode voltage potential from exceeding the cathode threshold 66 while the battery pack 10 is charging. A vertical axis 78 depicting the current of the charging current 68 is also shown, but no individual values ​​are shown because the accompanying values ​​vary widely depending on the type of cathode 14. For non-limiting purposes, the first and second charging current curves 72, 74 are shown to represent current adjustments that may be made throughout the charging process, or more specifically, changes that may be made when the cathode voltage potential approaches the cathode threshold 66, for example, when the cathode voltage potential is within a predetermined range of the cathode threshold 66. Once the predetermined range is reached, the charging current 68 may switch from the first charging current curve 72 to the second charging current curve 74, which may be characterized as the beginning of a second charging phase.

[0101] A constant cathode potential charging curve 64 is shown for non-limiting purposes with respect to a cathode threshold 66 and a charging current 68 defined relative to the voltage of the battery pack 10, which can be measured at the cathode of each battery pack 10 and at the battery pack level, by measuring the cathode of the battery pack 42. It is fully contemplated to use other values ​​besides voltage to depict the regulation of the charging current 68 and the interval at which the cathode voltage potential can approach the cathode threshold 66, such as the battery pack SOC can be used. For example, one non-limiting aspect of the present disclosure contemplates that the battery pack monitor 54 includes the ability to measure other values ​​that can be used in place of or in addition to the voltage to facilitate the depiction of the charging current curve and the cathode threshold. One such value can correspond to a direct measurement of the voltage potential of the cathode 14, such as using a sensor attached thereto and / or by calculation based on other metrics available to the battery pack monitor 54 (e.g., metrics derived from the battery pack 42 can be used to estimate the voltage potential at the cathode 14 of each battery pack 10). While the profile of the charging current 68 may be triggered or otherwise altered based on a measurable event, other mechanisms besides voltage and measured cathode voltage potential (eg, learning algorithms) may be employed without departing from the scope and spirit of the present disclosure.

[0102] Back to Figure 3 , block 82 relates to a cathode monitoring process, in which the charging of the battery pack 10 is monitored, for example, using the battery pack monitor 54 to determine whether the cathode 14 can be driven to a level where lithium plating may occur. This can include, for example, the battery pack monitor 54 monitoring the battery pack charging to determine whether the voltage potential 80 of the cathode 14 is approaching the cathode threshold 66. The monitoring can include evaluating the voltage potential at the cathode 14 and / or at an equivalent electrode of the battery pack 42, calculating the voltage of the battery pack 10 and / or the battery pack 42, or processing values ​​for plating characteristics derived based on the properties of the cathode 14. One non-limiting aspect of the present disclosure contemplates that the monitoring process is configured to determine when it may be necessary to reduce the battery pack charging current 68 supplied to the battery pack 10 in order to minimize or avoid conditions associated with the same plating of the cathode 14. Figure 4 An exemplary situation is shown where the battery pack charging current 68 may approach the cathode threshold at approximately 25% of the maximum voltage, however, this value may vary depending on the configuration, temperature, aging, and other characteristics of the battery pack 10. Block 84 involves continuing to charge the battery pack 10 according to the battery pack charging current set in block 62 in the event that block 82 fails to determine that the battery pack charge is approaching the cathode threshold 66.

[0103] Block 86 involves a second charging process that continues charging the battery pack 10 after adjusting the battery pack charging current 68 used in block 62. The second charging process may begin the second charging phase described above, whereby the battery pack charging current 68 is adjusted from the first charging curve 72 to the second charging curve 74. Figure 4 As shown, the second charging curve 74 may correspond to a decaying charging curve, whereby the battery charging current 68 may gradually decrease as the battery voltage increases. This decaying configuration of the second charging curve 74 may be different from the constant, non-decaying or consistent configuration of the first charging curve 72. Although the second charging curve 74 is shown as continuously decreasing as the battery charge level increases, the present disclosure fully contemplates second charging curves 74 with other configurations, including configurations in which the second charging curve 74 may temporarily increase the battery charging current 68 and / or make real-time adjustments to control the cathode charging potential as close to the cathode threshold 66 as possible without exceeding the cathode threshold 66, for example, to continuously maximize the battery charging current 68 without exceeding the cathode threshold 66. The granularity or accuracy with which the battery charging current 68 can be changed may vary depending on the capabilities of the battery pack 10, the battery pack 42 and / or the battery charger 56.

[0104] Figure 5 A cathode step function 92 for regulating the charging current 68 according to the second charging curve 74 according to one non-limiting aspect of the present disclosure is shown. The cathode step function 92 may include a plurality of step drops, which may correspond to a plurality of plateaus (not separately labeled) of the step line 94. The step drops may be defined relative to a plurality of voltage values ​​for measuring voltage, or optionally defined according to other metrics and values ​​for controlling battery charging, such as cathode potential values, etc. Each step drop may be used to gradually reduce the charging current 68 relative to each step drop defined relative to a larger one of the voltage values. The step drops may correspond to a gradual reduction in the battery charging current 68, which may be used in lieu of a more precise or granular regulation, i.e., unlike the smooth shape of the second charging curve 74, the step drops may provide a less precise or granular regulation of the battery charging current 68. For example, the cathode step function 92 may be implemented at the battery pack level in the manner shown, whereby the battery pack charger 56 may be configured to step down the battery pack charging current 68 supplied to the battery pack 42, which may then sequentially step down the battery pack charging current 68 supplied individually to each battery pack 10 included therein.

[0105] The constant cathode potential method 60 can be utilized in this manner to minimize or avoid lithium plating of the cathode 14. As described above, the constant cathode potential method 60 can be predicated on the fact that there is no need to correspondingly limit or otherwise adjust the battery pack charging to account for conditions associated with a plated anode 12. This ability to control the charging of the battery pack 10 based on the plating parameters of the cathode 14 can be simpler and require less processing than considering the plating characteristics of the anode 12. However, the present disclosure contemplates situations in which the constant cathode potential method 60 can be utilized to help minimize or avoid plating of the anode 12. To this end, Figure 6 A combined constant potential method 98 for minimizing or avoiding battery pack plating according to one non-limiting aspect of the present disclosure is shown. The method 98 can be used to minimize or avoid the above-mentioned lithium plating of both the anode 12 and the cathode 14. As described in more detail below, the method 98 can help prevent lithium plating by selectively controlling the charging of the battery pack 10 relative to the plating-related parameters determined for the anode 12 and the cathode 14.

[0106] The combined constant potential method 98 may be configured to minimize or avoid lithium plating of the battery 10 by adjusting the charging of the battery 10 according to plating characteristics derived based on the properties of both the anode 12 and the cathode 14. Block 100 relates to an initial charging process for beginning charging of the battery 10 in a process that may be referred to as a first charging stage, which may be similar to that described above in block 62. The first charging stage may correspond to the battery charger 56 determining a constant anode-cathode potential charging curve 102 for the battery 10. Figure 7 Such a constant anode-cathode potential charging curve 102 is shown in accordance with one non-limiting aspect of the present disclosure. The constant anode-cathode potential charging curve 102 may be determined based on operating characteristics of the anode 12, cathode 14, empirical testing, monitoring of the battery pack over time, etc. The constant anode-cathode potential charging curve 102 may be graphically represented relative to a cathode threshold 104 and an anode threshold 106, each defined relative to a voltage of the battery pack 10.

[0107] The cathode threshold 104 may be similar to that described above. The anode threshold 106 may be based on the properties of the anode 12 associated with lithium plating, i.e., represents the minimum voltage potential required for the anode 12 during charging. If the battery 10 is charged in a manner that causes charging to occur when the anode voltage potential is below the anode threshold 106 for an undesirable period of time, the anode 12 may potentially experience lithium plating. A vertical axis 108 depicting the voltages of the cathode and anode charging thresholds 104, 106 is shown, but no individual voltage values ​​are shown because the accompanying values ​​vary widely depending on the type of anode 12 and cathode 14. Figure 81 shows a cathode-anode current curve 110 according to one non-limiting aspect of the present disclosure. The anode-cathode charging current curve 110 can be used to define a plurality of charging curves 112, 114, 116 of a battery pack charging current 118, which can be used to Figure 7 The constant cathode-anode potential curve 102 shown minimizes or avoids lithium plating of the anode 12 and cathode 14 during charging. A vertical axis 120 of current depicting the charging current is shown, but individual values ​​are not shown because the accompanying values ​​vary widely depending on the type of anode 12 and cathode 14.

[0108] For non-limiting purposes, the anode-cathode charging current curve 110 is shown to represent current adjustments that may be made throughout the charging process, or more specifically, changes that may be made when the anode and / or cathode voltage potentials 124, 126 approach the cathode and anode thresholds 104, 106, respectively, for example, when the anode voltage potential 124 is within a predetermined range of the anode threshold 106 and / or the cathode voltage potential 126 is within a predetermined range of the cathode threshold 104. Once the predetermined range is reached, the charging current 118 may switch from the first charging current curve 112 to one or more additional charging curves 114, 116. The constant anode-cathode potential charging curve 102 is shown for non-limiting purposes with respect to the cathode and anode thresholds 104, 106 and the charging current 118 defined relative to voltage, however, as described above, other metrics may be utilized. Figure 7 An exemplary situation is shown in which, during charging, before the cathode voltage potential 126 approaches the cathode threshold 104, the anode voltage potential 124 approaches the anode threshold 106. In this situation, Figure 8 The anode-cathode charging current curve 110 shown in the figure may include a first charging curve 112, whereby a constant and non-decaying battery charging current or first charging current is provided to the battery 10, and then a second charging current curve 114 or anode charging curve may be implemented to prevent the anode potential 124 from exceeding the anode threshold 106. Thereafter, a third charging current curve 116, which may be a combined anode-cathode charging curve, may be implemented to prevent the cathode voltage potential 126 from exceeding the cathode threshold. The second and third charging curves 114, 116 are shown as gradually decaying curves, wherein the third charging curve 116 has a greater decay rate than the second charging curve 114.

[0109] Fig. 9 Such a constant cathode-anode potential charging curve 126 is shown in accordance with one non-limiting aspect of the present disclosure. Fig. 9 1 shows an exemplary situation where during charging, before the anode voltage potential 124 approaches the anode threshold 106, the cathode voltage potential 126 approaches the cathode threshold 104. In this case, the cathode voltage potential 126 may be used. Fig.10The cathode-anode charging current curve 128 is shown and includes a first charging curve 112, whereby a constant and non-decaying battery pack charging current or first charging current is provided to the battery pack 10, and then a second charging current curve 114 or cathode charging curve may be implemented to prevent the cathode potential 126 from exceeding the cathode threshold 104. Thereafter, a third charging current curve 116, which may be a combined cathode-anode charging curve, may be implemented to prevent the anode potential 124 from exceeding the anode threshold 106. The second and third charging curves 114, 116 are shown as gradually decaying curves, wherein the third charging curve 116 has a greater decay rate than the second charging curve 114. Return Figure 6 , block 132 involves a cathode monitoring process, whereby the charging of the battery 10 is monitored, for example, using the battery monitor 54, to determine whether the cathode 14 can be driven to a level where lithium plating may occur. Block 134 involves an anode monitoring process, whereby the charging of the battery 10 is monitored, for example, using the battery monitor 54, to determine whether the anode 12 can be driven to a level where lithium plating may occur. Block 136 involves continuing to charge the battery 10 according to the battery charging current 118 set in block 100 in the event that blocks 132, 134 fail to determine that the battery charging causes either the cathode potential 126 and the anode potential 124 to approach the cathode or anode threshold 104, 106.

[0110] Blocks 140, 142 relate to a second charging process that continues charging the battery pack 10 after adjusting the battery pack charging current 118 used in block 100. In response to the cathode voltage potential 126 approaching the cathode threshold 104 (e.g., Fig. 9 and Fig.10 ), the second charging process may be initiated in block 144 and in response to the anode voltage potential 124 approaching the anode threshold 106 (e.g., Figure 7 and Figure 8 ), the second charging process may be initiated in block 146. Blocks 150, 152 relate to a third charging process that continues charging the battery pack 10 after conditioning and one of blocks 144, 146. In response to the anode voltage potential 124 approaching the anode threshold 106 (e.g. Fig. 9 ), a third charging process may be initiated in block 150 and in response to cathode voltage potential 126 approaching cathode threshold 104 (eg Figure 7), the third charging process may be initiated in block 152. Although the combined constant cathode-anode potential method 98 is described with respect to including first, second, and third charging current curves 112, 114, 116, the present disclosure fully contemplates including additional charging current curves and / or curves having other shapes and configurations, including curves that may include increases and / or decreases in charging current.

[0111] As described above, the present disclosure relates to a charging method and a fast charging strategy based on a constant cathode potential and an optional anode potential. The expected control can be based on the constant cathode potential stage of the charging of the usual constant battery potential stage. This can accurately control the cathode potential, which is particularly important for high-energy (high nickel content) cathodes, which are more susceptible to damage and thermal runaway due to overcharging. The charging method may include a first stage of maximum current charging, a second stage of cathode constant potential charging, and a third stage of the constant battery potential stage. In the case of a reference electrode in the battery cell, the cathode constant potential charging current can be controlled by direct feedback control of the cathode to the reference potential. In the case where there is no reference electrode in the battery, the cathode constant potential charging current curve can be determined by previous testing. The determination of the cathode constant potential charging current curve can include cathode potential limit selection, generation of current curves by cathode constant potential charging experiments, charging curve scaling, and / or modification based on experimental curves. The cathode potential limit can be determined at its maximum available potential without showing limitations that may affect battery performance. The potential can be determined by cyclic voltammetry testing, capacity or coulomb efficiency analysis, or material analysis. The charging protocol may be selected based on the voltage and temperature at the start of charging, whereby the electrode is expected to be the limiting factor. If a reference electrode is available in the cell, this selection may be updated in real time during charging based on electrode potential feedback, or it may be defined by a lookup table pre-calibrated based on laboratory experiments with the same cell design. In some cases, the battery pack may be heated or cooled to a certain temperature in preparation for charging with a constant cathode potential protocol.

[0112] The terms "comprising", "including" and "having" are inclusive, thus specifying the presence of stated features, steps, operations, elements or components, but not excluding the presence or addition of one or more other features, steps, operations, elements or components. If possible, the order of steps, processes and operations can be changed, and additional or alternative steps can be adopted. As used in this specification, the term "or" includes any one and all combinations of the relevant listed items. The term "any one" is understood to include any possible combination of the referenced items, including "any one" of the referenced items. "One", "a kind", "the", "at least one" and "one or more" are used interchangeably to indicate the presence of at least one item. There may be multiple such items unless the context clearly indicates otherwise. All values ​​of parameters (such as amounts or conditions), unless otherwise clearly or clearly indicated according to the context (including the appended claims), should be understood to be modified by the term "about" in all cases, regardless of whether "about" actually appears before the value. A component "configured to" perform a specified function is able to perform the specified function without change, rather than only having the possibility to perform the specified function after further modification. In other words, when explicitly configured to perform a specified function, the hardware described is specifically selected, created, implemented, utilized, programmed, and / or designed for the purpose of performing the specified function.

[0113] Although various embodiments have been described, the description is intended to be exemplary rather than restrictive, and it is obvious to those of ordinary skill in the art that more embodiments and implementations within the scope of the embodiments are possible. Any feature of any embodiment may be used in combination with any other feature or element in any other embodiment or replace any other feature or element in any other embodiment, unless specifically limited. Therefore, the embodiments are not limited except according to the attached claims and their equivalents. In addition, various modifications and changes can be made within the scope of the attached claims. Although several modes for performing many aspects of this teaching have been described in detail, technicians familiar with the field to which these teachings belong will recognize various alternative aspects for practicing this teaching within the scope of the attached claims. It is intended that all the contents contained in the above description or shown in the drawings should be interpreted as an illustration and example of the entire range of alternative embodiments that ordinary technicians will recognize, which are structurally and / or functionally equivalent to, or become apparent in other ways based on the included content, and are not limited to only those embodiments that are clearly depicted and / or described.

Claims

1. A method for minimizing or avoiding lithium plating during direct current (DC) fast charging of a battery pack included in a vehicle, comprising: charging the battery pack during a first charging phase using a first charging current having a first charging curve; and A second charging phase is initiated to charge the battery pack using a second charging current having a cathode charging profile that gradually decays the second charging current to prevent a cathode potential of a cathode of the battery pack from exceeding a cathode threshold.

2. The method according to claim 1, further comprising: A third charging phase is initiated in which the battery is charged with a third charging current having an anode charging curve that gradually decays the third charging current to prevent an anode potential of an anode of the battery from exceeding an anode threshold.

3. The method according to claim 2, further comprising: The second charging phase begins after the first charging phase and before the third charging phase.

4. The method according to claim 3, further comprising: The first charging curve consistently maintains a first charging current in a non-decaying manner; The cathode charging curve gradually decays the second charging current at a first decay rate; and The anode charging curve gradually decays the third charging current at a second decay rate greater than the first decay rate.

5. The method according to claim 2, further comprising: After the first charging phase and after the third charging phase, a second charging phase begins.

6. The method according to claim 5, further comprising: The first charging curve consistently maintains a first charging current in a non-decaying manner; The anode charging curve gradually decays the second charging current at a first decay rate; and The cathode charging curve gradually decays the third charging current at a second decay rate greater than the first decay rate.

7. The method according to claim 2, further comprising: Monitor cathode potential; and A second charging phase is initiated in response to the cathode potential being within a predetermined cathode range of the cathode threshold.

8. The method according to claim 7, further comprising: monitoring anode potential; and A third charging phase is initiated in response to the anode potential being within a predetermined anode range of the anode threshold.

9. The method according to claim 2, further comprising: Monitor the state of charge (SOC) of the battery pack; and A second charging phase is initiated in response to the SOC exceeding the cathode SOC threshold.

10. The method according to claim 9, further comprising: Monitor the state of charge (SOC) of the battery pack; and A third charging phase is initiated in response to the SOC exceeding the anode SOC threshold.

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