Battery system for a motor vehicle, method for managing a battery system and motor vehicle

Abstract

A battery system for a powered vehicle is provided, including at least one first battery unit comprising a plurality of first monobloc batteries and at least one second battery unit comprising a plurality of second monobloc batteries and an electrolyte flow device, the second monobloc batteries having a higher energy density than the first monobloc batteries, the electrolyte flow device comprising a reservoir in communication with each of the second monobloc batteries, the electrolyte flow device configured to draw electrolyte from the second monobloc batteries to the reservoir or to inject electrolyte from the reservoir to the second monobloc batteries. The electrolyte flow device can draw electrolyte from the high energy density battery units without requiring the use of the second battery pack to power the powered vehicle, such that the high energy density battery units, which are used less frequently, can exhibit a longer cycle life.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power vehicles, in particular to a battery system for a power vehicle, a management method thereof and a power vehicle. BACKGROUND

[0002] Lithium batteries have been widely used in portable electronic products such as mobile phones, notebook computers, and new energy vehicles. At present, the energy density of commercial lithium batteries based on traditional graphite negative electrodes has reached the ceiling and cannot meet the increasing demand for endurance and standby. Lithium metal has a high theoretical specific capacity (3861 mAh / g) and the most negative electrochemical potential (-3.04 V, relative to the standard hydrogen electrode), and is considered to be the best choice for the next generation of high-energy-density battery negative materials.

[0003] However, in the actual use of power vehicles, the scenario of using high-energy-density batteries does not occur frequently, such as usually only when driving long distances during holidays, so that the high-energy-density batteries will undergo side reactions between the electrode and the electrolyte during long-term storage, especially the side reactions between the highly chemically active lithium metal negative electrode and the electrolyte are more serious, which affects the subsequent high energy performance in the scenario requiring long endurance and reduces the cycle life. SUMMARY

[0004] Therefore, the present application provides a power vehicle and a management method of a battery system thereof, so that the high-energy-density battery unit with low frequency of use in the power vehicle exhibits a longer cycle life.

[0005] Specifically, in a first aspect, the present application provides a battery system for a power vehicle, wherein the battery system comprises at least one first battery unit and at least one second battery unit, the first battery unit comprises a plurality of first single batteries, the second battery unit comprises a plurality of second single batteries, and the energy density of the second single battery is higher than that of the first single battery; wherein the second battery unit further comprises an electrolyte flow device, the electrolyte flow device comprises a liquid storage tank, and the cavity of each second single battery is in communication with the liquid storage tank; wherein the electrolyte flow device is used to draw the electrolyte in the second single battery to the liquid storage tank when the second battery unit is not needed to power the power vehicle.

[0006] In a second aspect, the application further provides a management method of a battery system for a power vehicle, wherein the battery system comprises at least one first battery unit and at least one second battery unit, the first battery unit comprises a plurality of first single batteries, the second battery unit comprises a plurality of second single batteries and an electrolyte flow device, the electrolyte flow device comprises a reservoir, and a cavity of each of the second single batteries is in communication with the reservoir, and the energy density of the second single batteries is higher than that of the first single batteries.

[0007] The management method comprises: when the second battery unit is not required to supply power to the power vehicle, the electrolyte flow device draws the electrolyte in the second single batteries to the reservoir.

[0008] The battery system or the management method thereof provided by the embodiments of the application can draw the electrolyte in the second battery unit with a high energy density and used less frequently in the power vehicle when it is not required to supply power, so as to avoid capacity loss, thereby enabling the second battery unit to exhibit a higher capacity and a longer cycle life when it is required to supply power.

[0009] In a third aspect, the application further provides a power vehicle having the battery system of the first aspect of the application. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 A structural schematic diagram of the power vehicle provided by the embodiments of the application.

[0011] Figure 2 For Figure 1 A structural schematic diagram of the first battery unit.

[0012] Figure 3 For Figure 1 A structural schematic diagram of the second battery unit.

[0013] Figure 4 For Figure 1 Another structural schematic diagram of the second battery unit.

[0014] Figure 5 An exemplary structural schematic diagram of the second single battery. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the application will be described in detail below with reference to the drawings.

[0016] The embodiments of the application provide a power vehicle, a battery system of the power vehicle and a management method of the battery system.

[0017] Referring to Figure 1The power vehicle 300 provided in the present application can include at least one first battery unit 10 and at least one second battery unit 20. In the embodiments of the present application, one first battery unit 10 and one second battery unit 20 are taken as an example for illustration. The first battery unit 10 and the second battery unit 20 can both communicate with the driving part 301 of the power vehicle 300. The power vehicle can be an electric vehicle, for example. The driving part 301 can be an electric motor.

[0018] Each first battery unit 10 includes a plurality of first single battery 110, and each second battery unit 20 includes a plurality of second single battery 210, wherein the energy density of the second single battery 210 is higher than that of the first single battery 110. The first battery unit 10 with low energy density is mainly used for short and medium distance use in daily mode, and the second battery unit 20 with high energy density is mainly used for long distance travel, so that the power vehicle can achieve the required long endurance mileage, which can be used in combination with the first battery unit 10. It should be noted that when there are a plurality of second battery units 20, the second battery units can be in parallel relationship, and when one second battery unit is fully discharged, other second battery units can be used.

[0019] In the present application, the first battery unit 10 and the second battery unit 20 can be a "non-module" battery pack or a "module" battery pack. In some embodiments of the present application, referring to Figure 2 , the first battery unit 10 can be a module battery pack, which can include a first battery group 11 and a battery management system (BMS) 12. The first battery group 11 can be a module formed by a plurality of first single batteries 110 in series, parallel or a combination thereof. The BMS 12 is used to monitor the state information of each single battery in the first battery group 11, such as voltage, current, internal resistance, temperature, etc., and control the charge / discharge of each single battery. The BMS 12 generally includes detectors and controllers, etc. The BMS 12 can have an interface (not shown in the figure) for performing communication between the BMS 12 and external devices (loads or charging devices). The interface can be a controller area network (CAN) interface, for example. The charging device can be a charging station, and the load can be the driving part 301 of the power vehicle.

[0020] Since the energy density of the second monomer battery 210 in the second battery unit 20 is high, the negative active material thereof usually contains lithium metal (i.e., lithium element and / or lithium alloy) or silicon-based material, and since the side reaction between these materials (especially lithium metal) and the electrolyte is generally more serious than that of low-energy-density batteries (such as batteries with graphite as the negative electrode), especially the side reaction between the chemically active lithium metal and the electrolyte is more serious. In the actual use of a power vehicle, the scenario of using a high-energy-density battery does not occur frequently, such as when a long-distance trip is needed during a holiday, which causes the high-energy-density battery in a charged state to be left for a long time in a normal period, resulting in a more serious side reaction between the electrode and the electrolyte, and further causing a large loss of active materials and electrolyte and capacity decay, etc., affecting the cycle life of the battery, reducing safety, and also affecting the energy performance in subsequent scenarios requiring long endurance.

[0021] Therefore, in the embodiments of the present application, the second battery unit 20 further comprises an electrolyte flow device 2 (please continue to refer to Figure 1 ), which comprises a liquid storage device 201 in communication with the cavities of the second monomer batteries 210. The electrolyte flow device 2 can communicate with the vehicle driving part 301. According to specific needs, the electrolyte flow device 2 can be used to draw the electrolyte in each second monomer battery 210 to the liquid storage device 201 when the second battery unit 20 is not needed to power the power vehicle. Of course, the electrolyte flow device 2 can also be used to inject the electrolyte in the liquid storage device 201 back into each second monomer battery 210 when the second battery unit 20 is needed to power the power vehicle.

[0022] With the battery system shown in Figure 1 , the side reaction between the electrolyte and the electrode active material in the second battery unit 20 that does not exercise the power supply function can be avoided, and the capacity decay of the battery can be avoided, so that the second battery unit 20 can withstand more charge and discharge cycles when used subsequently.

[0023] Specifically, in some embodiments, referring to Figure 3The electrolyte flow device 2 of the second battery unit 20 may include a reservoir 201, a central processing unit 202, a power mechanism 203, and multiple solenoid valves 204. The power mechanism 203 is connected to the reservoir 201 and each second individual battery cell 210 via a conduit. Each second individual battery cell 210 is connected to the power mechanism 203 via a solenoid valve 204. The power mechanism 203 and the solenoid valves 204 are electrically connected to the central processing unit 202. The central processing unit 202 can control the opening time of the power mechanism 203 and the solenoid valves 204, as well as the opening degree of each solenoid valve, to control the flow rate of the electrolyte in each conduit. Specifically, the central processing unit 202 can communicate with the vehicle drive unit 301. The central processing unit 202 can be configured inside the BMS of the second battery unit 20, for example, integrated into the controller of the BMS of the second battery unit 20. Alternatively, the central processing unit 202 can be a separate module electrically connected to the BMS of the second battery unit (in which case, the two can be connected via a CAN bus).

[0024] The following is based on Figure 3 Taking the second battery cell as an example, the electrolyte flow device 2 is described. When the power vehicle 300 activates the first operating mode, the electrolyte flow device 2 is used to draw the electrolyte in the second single cell 210 to the reservoir 201. In the first operating mode, only the first battery cell 10 supplies power to the power vehicle 300.

[0025] Figure 3 In the illustrated embodiment, the electrolyte flow device 2 determines whether to retain electrolyte in the second battery cell 210 based on whether the vehicle needs to activate the first operating mode with short range (i.e., whether the second operating mode with long range described below is not needed, as the high-energy-density second battery cell 20 does not need to provide power in the first operating mode). If the vehicle needs to activate the first operating mode, the central processing unit 202 controls the power mechanism 203 and the solenoid valve 204 to open, drawing the electrolyte from the second battery cell 210 to the reservoir 201, allowing the second battery cell 20 to be in a "dormant" state without electrolyte. This avoids side reactions between the electrolyte and electrode active materials, battery capacity decay, etc., in the second battery cell 20 that is not providing power, ensuring that the second battery cell 20 can withstand long-term storage and can withstand a large number of charge-discharge cycles in the future.

[0026] Further, the electrolyte circulating device 2 is configured to inject the electrolyte back into the second single battery 201 when receiving a switching instruction of switching the power vehicle 300 from the first operation mode to the second operation mode, and the power vehicle 300 is configured to switch from the first operation mode to the second operation mode, wherein in the second operation mode, the first battery unit 10 and the second battery unit 20 supply power to the power vehicle 300.

[0027] Figure 3 In the embodiment shown, when the power vehicle needs the second battery unit 20 with high energy density to participate in power supply, for example, the central processing unit 202 of the electrolyte circulating device 2 receives a switching instruction of switching the power vehicle 300 from the first operation mode to the second operation mode, then the central processing unit 202 controls the power mechanism 203 and the electromagnetic valve 204 to open, injects the electrolyte in the liquid storage tank 201 back into the second single battery 201, activates the second battery unit 20 in the "sleeping" state, and then realizes the power supply of the power vehicle 300 by the first battery unit 10 and the second battery unit 20 after the power vehicle 300 switches from the first operation mode to the second operation mode. In this way, the rapid activation of the second battery unit 20 can be realized on demand.

[0028] Therefore, the battery system and the power vehicle implementing the embodiment of the present application can make the second battery unit with high energy density, which is not frequently used, to be drained of electrolyte when it is not needed to supply power, and to be injected with electrolyte when it is needed to supply power, so that the second battery unit can exhibit high energy density when used, and also has a long cycle life.

[0029] In particular, the above-mentioned "pumping the electrolyte in the second battery cell 210 to the reservoir 201" can be performed after the second battery cell 20 is charged to a certain amount of electricity, for example, can be after charging to 50% SOC or after fully charging. For example, in some embodiments, the electrolyte circulation device 2 can be used to pump the electrolyte in the second battery cell 210 to the reservoir 201 after the second battery cell 20 is charged to a SOC greater than or equal to a first threshold, and the power vehicle 300 receives an instruction to enable the first operating mode. In this case, the pumping of the electrolyte needs to meet two conditions at the same time: 1) receiving an instruction from the power vehicle 300 to enable the first operating mode; 2) the second battery cell 20 is charged to a SOC greater than or equal to the first threshold. After meeting the two conditions at the same time, the pumping of the electrolyte is performed. It can be understood that the charging of the second battery cell 20 should be stopped before the operation of pumping the electrolyte in the second battery cell 210 is performed, and generally the pumping of the electrolyte will not be performed at the same time as the charging, and of course the second battery cell 210 will not be charged after the electrolyte in the second battery cell 210 is pumped out. After the electrolyte in the second battery cell 210 that is charged to a certain amount of electricity is pumped to the reservoir 201, the second battery cell 20 is in an "sleeping" state with electricity, which facilitates the subsequent quick recovery of the power supply function when it is activated, and avoids the long charging time before the second battery cell 20 is enabled.

[0030] The instruction from the power vehicle 300 to enable the first operating mode (i.e., the above-mentioned condition 1) can be received before the second battery cell 20 is charged, or received during the charging of the second battery cell 20, such as before or when the second battery cell 20 is charged to a SOC greater than or equal to the first threshold, but the "pumping the electrolyte in the second battery cell 210 to the reservoir 201" needs to be performed when the SOC of the second battery cell 20 is greater than or equal to the first threshold. If the instruction is received during the charging of the second battery cell 20, the electrolyte circulation device 2 needs to first determine whether the second battery cell 20 is charged to greater than or equal to the first SOC threshold, if yes, stop charging the second battery cell 20, and the electrolyte circulation device 2 performs the operation of pumping the electrolyte in the second battery cell 210 to the reservoir 201. If the instruction is received before the second battery cell 20 is charged, the second battery cell 20 can be directly charged to greater than or equal to the first SOC threshold (preferably fully charged), and then the electrolyte circulation device 2 performs the operation of pumping the electrolyte in the second battery cell 210 to the reservoir 201.

[0031] SOC (State of Charge) is a parameter reflecting the percentage of the current charge in the total available capacity. When the SOC of the second battery unit is at the first threshold, the second battery unit has a longer driving range per unit weight or unit volume than the first battery unit when fully charged. In other words, the energy density of the second battery unit when the SOC is at the first threshold is greater than that of the first battery unit when fully charged. In this way, when the second battery unit needs to be powered with SOC≥the first threshold, it can exhibit long driving characteristics. For example, the first threshold can be 50%, 60%, 70%, 80%, 90%, 95%, or 100%, etc. The specific first threshold and the actual SOC value of the second battery unit can be determined according to the driving range that can be exhibited when the second battery unit needs to be powered.

[0032] Preferably, the first threshold can be 100% SOC. That is, when the second battery unit 20 is fully charged and the power vehicle 300 receives an instruction to enable the first operating mode, the electrolyte in the second battery cell 210 is pumped to the reservoir 201 by the electrolyte circulation device 2. At this time, after the electrolyte of the fully charged second battery unit 20 is pumped out, it is in a full charge "sleep" state, and when the electrolyte is injected back, it is quickly activated and can maximize its high energy density characteristics, thereby making the driving range of the power vehicle longer.

[0033] It should be noted that if the electrolyte circulation device 2 receives an instruction that the power vehicle does not enable the first operating mode after the second battery unit 20 is charged to a SOC greater than or equal to the first threshold (i.e., the vehicle needs to start the second operating mode that requires the second battery unit 20 to power it), the electrolyte circulation device 2 does not perform any operation, and the electrolyte in the second battery unit 20 is still in each second battery cell, and the second battery unit 20 can subsequently directly participate in providing power to the power vehicle together with the first battery unit 10.

[0034] In addition, if the second battery unit 20 has not been used to supply power to the power vehicle 300 during the operation of the power vehicle 300 after the charging (i.e., the second battery unit 20 is always in the state of having electricity without electrolyte), only the first battery unit 10 needs to be charged when the battery system of the power vehicle 300 is charged. If the second battery unit 20 has been used to supply power to the power vehicle 300 during the operation of the power vehicle 300 (e.g., still has electricity left), both the first battery unit 10 and the second battery unit 20 can be charged when the battery system of the power vehicle 300 is charged, and the second battery unit 20 is preferably fully charged; of course, if it is considered that the second battery unit 20 will not be used subsequently, the second battery unit 20 can also not be charged, and the electrolyte in the second battery unit 20 can still be in the state of having electricity without electrolyte when the power vehicle receives the instruction to activate the first operation mode, but the second battery unit 20 can have little electricity left when it is activated.

[0035] The first operation mode can be referred to as a "short-range mode" or a "daily mode", which is the most commonly used mode of the power vehicle. The second operation mode can be referred to as a "long-range mode" or a "holiday mode", which is an occasional mode of the power vehicle. In addition to being distinguished according to the power supply battery unit, the two modes can also be distinguished according to the range, for example, the range of the first operation mode can be more than 450 km, for example, 500-600 km, and the range of the second operation mode can be more than 900 km, for example, 1100-1500 km. In the first or second operation mode of the power vehicle 300, the first battery unit 10 with low energy density is used to supply power to the vehicle, and obviously, the first battery unit 10 always has electrolyte.

[0036] Figure 3 In some embodiments, each second battery cell 210 has a connection pipe with the power structure 203, and the extraction and injection of the electrolyte in the second battery cell 210 are performed by the same power structure 203. In other embodiments, referring to Figure 4 The electrolyte circulation device 2 can include a reservoir 201, a central processing unit 202, an extraction pump 2031, and an injection pump 2032, which are respectively connected by pipes between the reservoir 201 and each second battery cell 210. Each second battery cell 210 communicates with the extraction pump 2031 through an extraction pipe 2041a, and each second battery cell 210 communicates with the injection pump 2032 through an injection pipe 2042a. Each extraction pipe 2041a is provided with an extraction valve 2041, and each injection pipe 2042a is provided with an injection valve 2042. The extraction pump 2031, the injection pump 2032, the extraction valve 2041, and the injection valve 2042 are electrically connected to the central processing unit 202.

[0037] Figure 4 In this process, the extraction of electrolyte from the second single-cell battery 210 is performed as follows: the central processing unit 202 controls the opening of the extraction pump 2031 and each extraction valve 2041, and the electrolyte in the second single-cell battery 210 is extracted to the reservoir 201 via the extraction pipe 2041a. The return of electrolyte to the second single-cell battery 210 is performed as follows: the central processing unit 202 controls the opening of the injection pump 2032 and each injection valve 2042, and the electrolyte in the reservoir 201 is returned to the second single-cell battery 210 via the injection pipe 2042a. Figure 3 The power structure 203 in the pump is a bidirectional pump that can rotate in both forward and reverse directions. Figure 4 Both the pump 2031 and the injection pump 2032 are unidirectional pumps, capable of rotating in either direction. These pumps can be conventional liquid pump devices, such as peristaltic pumps.

[0038] and Figure 3 Similarly, implementation Figure 4 The battery system and power vehicle shown can have their electrolyte removed when the high-energy-density second battery cell is not needed to power the vehicle; when it is needed to power the vehicle, its electrolyte is injected back to quickly restore the power supply function, thus enabling the second battery cell to achieve both high energy density and long cycle life.

[0039] Optionally, the above-mentioned reservoir 201 may be equipped with a sensor for detecting the liquid level in the reservoir 201 to determine when to stop drawing out or injecting electrolyte.

[0040] Optionally, Figure 3 An electrolyte purification device can be connected to each injection pipe 2042a or the outlet of the reservoir to purify the electrolyte flowing out of the reservoir before injecting it into the second battery unit. This electrolyte purification device can be a filter screen or a filter membrane, etc.

[0041] Furthermore, to facilitate understanding of the connection between the second single cell 210 and the electrolyte flow device 2, the structure of the second single cell 210 will be briefly described below. Figure 5 An exemplary structure for a first single-cell battery is provided. See also Figure 5The second single battery 210 includes a shell 210a having a cavity (indicated by a solid arrow) and an electrode core 200 disposed in the cavity. The electrode core 200 includes a negative electrode sheet 211, a positive electrode sheet 212, and a separator 213 and an electrolyte (not shown) between the negative electrode sheet 211 and the positive electrode sheet 212. The shell of the second single battery 210 further includes a channel (indicated by a dashed arrow) in communication with the cavity, so as to facilitate communication between the second single battery 210 and the liquid reservoir 201 and the power mechanism, and facilitate extraction and injection of the electrolyte in the second single battery 210. In addition, the positive electrode sheet 212 generally includes a positive electrode current collector 2120 and a positive electrode material layer 2122 disposed on the positive electrode current collector 2120, and the positive electrode material layer 2122 contains a positive electrode active material, and optionally a conductive agent and a binder. Similarly, the negative electrode sheet 211 generally includes a negative electrode current collector 2110 and a negative electrode material layer 2111 disposed on the negative electrode current collector 2110, and the negative electrode material layer 2111 contains a negative electrode active material, and optionally a conductive agent and a binder.

[0042] In the present application, the energy density of the first single battery is lower than that of the second single battery. In some embodiments of the present application, the negative electrode active material in the first single battery can include graphite, a silicon-based material including one or more of elemental silicon, silicon oxide, silicon-based alloy, and silicon-carbon composite material. The negative electrode active material in the second single battery 210 can include at least one of lithium metal (including lithium element and / or lithium alloy), silicon-based material, and preferably lithium element and / or lithium alloy. For example, the lithium alloy can be one or more of lithium-silicon alloy, lithium-tin alloy, lithium-magnesium alloy, lithium-zinc alloy, etc.

[0043] The electrolyte for the first battery cell 10 is conventionally selected in the art and generally contains a lithium salt and a solvent. In particular, the electrolyte solvent for the first battery cell 10 is generally an ester-based solvent, such as a substituted or unsubstituted carbonate, carboxylate, etc. When the negative electrode active material in the second single battery 210 includes lithium metal, in order to match the high chemical reactivity of lithium metal, the electrolyte solvent for the second single battery 210 in the present application includes an ether-based solvent, and in particular can include at least one of an unhalogenated ether-based solvent and a fluorinated ether-based solvent. In particular, the ether-based solvent has good compatibility with lithium metal, and the side reaction between the ether-based solvent and lithium metal is much lower than that of carbonate-based solvents, which can effectively inhibit the consumption of active lithium during the cycling process, and is more inclined to dense deposition during the deposition growth process.

[0044] Optionally, the unhalogenated ether solvent may be selected from one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether, but is not limited thereto. Optionally, the fluorinated ether solvent may be selected from 1,1,2,2-tetrafluoroethyl ethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, hexafluoroisopropyl ethyl ether, tetrafluoroethyl-tetrafluoropropyl ether, 2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, difluoromethyl-2,2,3,3-tetrafluoropropyl ether, 2,2,3 One or more of the following, but not limited to: 3,3-pentafluoropropyl methyl ether, 1,1,2,3,3,3-hexafluoropropyl ethyl ether, 1,1,2,3,3,3-pentafluoropropyl difluoromethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, and bis(2,2,2-trifluoroethyl) ether.

[0045] In some embodiments of this application, in the second single-cell battery 210, the surface of the negative electrode active material is covered with a protective layer, or the surface of the negative electrode sheet 211 near the separator (i.e., the surface of the negative electrode material layer 2111) is covered with a protective layer 2112 (see [reference]). Figure 4 The protective layer 2112 contains a polymer matrix and a second lithium salt. This protective layer is in a non-dissolved state in the battery electrolyte. It guides the lithium-ion flow, controls the uniform deposition of lithium ions on the negative electrode surface, effectively inhibits the growth of lithium dendrites on the surface of the negative electrode 211 and prevents them from piercing the separator. Furthermore, it reduces side reactions between the negative electrode and the electrolyte when elemental lithium is deposited at the negative electrode, alleviates the volume expansion of the negative electrode during cycling, and improves the battery's cycle performance and safety performance.

[0046] Specifically, the polymer matrix may include, but is not limited to, one or more of polyethylene oxide (PEO), polysiloxane, polyvinylidene fluoride, polymethyl methacrylate, polyacrylonitrile and its derivatives and copolymers. The second lithium salt has ionic conductivity and may include one or more of lithium nitrate (LiNO3), lithium sulfide (Li2S), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), lithium fluoride (LiF), and lithium phosphate (Li3PO4). In some embodiments, the protective layer may also contain inorganic fillers to increase lithium-ion transport channels and improve mechanical properties. The inorganic filler may be at least one of oxides (such as silicon dioxide, alumina, titanium dioxide, etc.), hydroxides (such as aluminum hydroxide, magnesium hydroxide), and salts.

[0047] The positive active material in the first battery unit 10 and the second battery unit 20 is a conventional material in the battery field, and can be independently selected from at least one of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium cobaltate, lithium manganate, lithium nickel manganate, lithium nickel cobalt manganate (NCM), lithium nickel cobalt aluminum (NCA), and the like. The binder and the conductive agent in the negative electrode sheet and the positive electrode sheet can also use conventional materials. For example, the conductive agent can use one or more of conductive carbon black (such as acetylene black, ketjen black), carbon nanotubes, carbon fibers, graphite, and furnace black. And the binder can independently use one or more of styrene butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyimide (PI), polyacrylic acid (PAA), polyolefins (such as polyethylene, polypropylene, etc.), sodium carboxymethyl cellulose (CMC), and sodium alginate. The negative current collector and the positive current collector are independently selected from metal single-foil or alloy foil. For example, the negative current collector can be a copper foil, and the positive current collector can be an aluminum foil.

[0048] The application also provides a management method for the battery system of a power vehicle. The overall architecture of the battery system and the power vehicle can refer to the above Figures 1-4 , which will not be repeated here.

[0049] The battery system includes at least one first battery unit 10 and at least one second battery unit 20, the first battery unit 10 includes a plurality of first single batteries 110, and the second battery unit 20 includes a plurality of second single batteries 210. The energy density of the second single battery 210 is higher than that of the first single battery 110. The second battery unit 20 further includes an electrolyte flow device 2, which includes a liquid storage tank 201. The cavity of each second single battery 210 is in communication with the liquid storage tank 201.

[0050] Referring to the structural schematic diagram of Figure 1 , the management method includes: when the second battery unit 20 is not needed to supply power to the power vehicle 300, the electrolyte flow device 2 draws the electrolyte in the second single battery 210 to the liquid storage tank 2. In this way, as long as the second battery unit 20 is not needed to supply power, the electrolyte is drawn away, which almost maximally avoids the self-discharge and the side reaction between the electrolyte and the positive / negative electrode material during the long-term storage of the second battery unit, avoids the capacity attenuation, and improves the cycle life. In some embodiments of the application, the step can be specifically performed as follows: when an instruction to enable a first running mode of the power vehicle 300 is received, the electrolyte flow device 2 draws the electrolyte in the second single battery 210 to the liquid storage tank 2; in the first running mode, only the first battery unit 10 supplies power to the power vehicle 300.

[0051] Of course, in another embodiment of the application, the electrolyte flow device 2 can draw the electrolyte in the second battery unit 20 to the reservoir 2 upon receiving an instruction from the power vehicle 300 to activate the first operation mode after the second battery unit 20 is charged to a SOC greater than or equal to the first threshold. At this time, the second battery unit 20 is in an electrified "dormant" state, which not only prevents self-discharge and side reactions between the electrolyte and the electrode material in a long-term non-use state, but also facilitates the subsequent rapid recovery of the power supply function when it is activated, avoiding the long charging time before activating the second battery unit 20. Alternatively, the above "after the second battery unit 20 is charged to a SOC greater than or equal to the first threshold" can be "after the second battery unit 20 is fully charged".

[0052] Further, upon receiving a switching instruction from the power vehicle 300 to switch from the first operation mode to the second operation mode, the electrolyte flow device 2 injects the electrolyte back into the second battery unit 20 and switches the power vehicle from the first operation mode to the second operation mode, wherein in the second operation mode, the first battery unit 10 and the second battery unit 20 supply power to the power vehicle 300. After the electrolyte flow device 2 injects the electrolyte in the reservoir 2 back into the second battery unit 20, the second battery unit 20 in the electrified "dormant" state can be activated, and then after the electrolyte flow device 2 switches the power vehicle 300 from the first operation mode to the second operation mode (i.e., controls the electrical connection between the second battery unit 20 and the vehicle drive 301 to allow the discharge current between them), the first battery unit 10 and the second battery unit 20 can jointly supply power to the power vehicle 300.

[0053] It should be noted that in the present application, the instruction for the power vehicle 300 to activate the first operation mode can be issued by the user of the power vehicle pressing the mode button of the vehicle operation panel, or by the user remotely operating the app on the terminal such as a mobile phone that can communicate with the vehicle, etc., but is not limited thereto. Similarly, the switching instruction for switching the power vehicle from the first operation mode to the second operation mode can also be issued by the user pressing the mode button of the vehicle operation panel, etc.

[0054] Therefore, for the battery system of the embodiment of the application Figure 1 The above management method can be implemented for the battery system, so that the second battery unit with a lower use frequency and a high energy density can have the electrolyte drawn away when it is not needed to supply power, and the electrolyte injected back to quickly exert the power supply function when it is needed to supply power, so that the second battery unit can exert a higher energy density and have a longer cycle life.

[0055] Similarly, for the battery system Figure 1 with the above Figure 3 or Figure 4The vehicle battery system of the second battery unit also implements the above management method, and the second battery unit with low use frequency and high energy density can also have its electrolyte drawn out when it is not needed to supply power, so as to avoid capacity loss, and the electrolyte is injected back when it is needed to supply power, so as to quickly realize the power supply function, thereby the second battery unit can realize high energy density and long cycle life. However, for the structure shown in the embodiment, the electrolyte in the second battery unit 210 is drawn to the reservoir 2 and the electrolyte in the reservoir 2 is injected back to the second battery unit 210 by the central processing unit 201 controlling the power mechanism 201 and the electromagnetic valve 204 to open. Figure 3 For the structure shown in the embodiment, the electrolyte in the second battery unit 210 is drawn to the reservoir 2 by the central processing unit 201 controlling the drawing pump 2031 and the drawing valve 2041 to open, and the electrolyte in the reservoir 2 is injected back to the second battery unit 210 by the central processing unit 201 controlling the injection pump 2032 and the injection valve 2042 to open. Figure 4 For the structure shown in the embodiment, the electrolyte in the second battery unit 210 is drawn to the reservoir 2 by the central processing unit 201 controlling the drawing pump 2031 and the drawing valve 2041 to open, and the electrolyte in the reservoir 2 is injected back to the second battery unit 210 by the central processing unit 201 controlling the injection pump 2032 and the injection valve 2042 to open.

[0056] The above-described embodiments only express several exemplary embodiments of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A battery system for a powered vehicle, characterized in that, The battery system includes at least one first battery unit and at least one second battery unit. The first battery unit includes multiple first individual cells, and the second battery unit includes multiple second individual cells, wherein the energy density of the second individual cells is higher than that of the first individual cells. The second battery unit further includes an electrolyte flow device, which includes a reservoir. The cavity of each second individual cell is connected to the reservoir. The electrolyte flow device is used to draw electrolyte from the second individual cells to the reservoir when the second battery unit is not needed to power the vehicle. Wherein, the "electrolyte flow device is used to draw electrolyte from the second individual battery cell to the reservoir when the second battery cell is not needed to power the vehicle" includes: The electrolyte flow device is used to draw electrolyte from the second individual battery cell into the reservoir after the second battery cell is charged to a state of charge (SOC) greater than or equal to a first threshold and after receiving an instruction from the power vehicle to activate a first operating mode; wherein, in the first operating mode, only the first battery cell supplies power to the power vehicle.

2. The battery system as claimed in claim 1, characterized in that, The electrolyte flow device is also used to inject the electrolyte back into the second single cell when receiving a switching command from the power vehicle to the second operating mode, wherein the power vehicle is configured to switch from the first operating mode to the second operating mode. In the second operating mode, the first battery unit and the second battery unit jointly supply power to the vehicle.

3. The battery system according to any one of claims 1-2, characterized in that, The electrolyte flow device further includes a central processing unit and a power mechanism. The power mechanism is connected between the reservoir and each of the second individual cells. Each of the second individual cells is equipped with a solenoid valve on the connection pipe between the power mechanism and the power mechanism. Both the power mechanism and the solenoid valve are electrically connected to the central processing unit. The power mechanism is used to pump the electrolyte from the second cell to the reservoir and to inject the electrolyte back into the second cell.

4. The battery system according to any one of claims 1-2, characterized in that, The electrolyte flow device further includes a central processing unit and a power mechanism. The power mechanism includes a liquid extraction pump and a liquid injection pump. The power mechanism is connected via a pipeline between the electrolyte reservoir and each of the second individual cells. Each of the second individual cells is connected to the liquid extraction pump via a liquid extraction pipeline, and each of the second individual cells is connected to the liquid injection pump via a liquid injection pipeline. Each liquid extraction pipeline is equipped with a liquid extraction valve, and each liquid injection pipeline is equipped with a liquid injection valve. The liquid extraction pump, the liquid injection pump, and the liquid extraction valve are all electrically connected to the central processing unit. The pump is used to pump the electrolyte from the second cell to the reservoir, and the pump is used to inject the electrolyte back into the second cell.

5. The battery system as claimed in claim 1, characterized in that, The second single-cell battery includes a casing and a cell located in the internal cavity of the casing. The cell includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode. The negative electrode contains a second negative electrode material layer, and the second negative electrode material layer contains a second negative electrode active material including elemental lithium and / or lithium alloy. The first negative electrode active material in the first single cell includes graphite and silicon-based materials, wherein the silicon-based materials include one or more of elemental silicon, silicon oxide, silicon-based alloys and silicon-carbon composite materials.

6. The battery system as claimed in claim 5, characterized in that, When the second battery cell is used for power supply, the cell of the second single battery also includes an electrolyte located between the positive electrode and the negative electrode; wherein, the solvent in the electrolyte used for the second single battery includes an ether solvent, and the ether solvent includes at least one of unhalogenated ether solvent and fluorinated ether solvent.

7. The battery system as claimed in claim 5, characterized in that, The surface of the second negative electrode material layer or the surface of the second negative electrode active material has a protective layer, wherein the protective layer contains a polymer matrix and a lithium salt.

8. A method for managing a battery system for a power vehicle, characterized in that, The battery system includes at least one first battery unit and at least one second battery unit. The first battery unit includes multiple first individual cells, and the second battery unit includes multiple second individual cells and an electrolyte flow device. The electrolyte flow device includes a reservoir. The cavity of each second individual cell is connected to the reservoir. The energy density of the second individual cell is higher than that of the first individual cell. The management method includes: when the second battery cell is not needed to power the vehicle, the electrolyte flow device draws the electrolyte from the second single cell to the reservoir; Wherein, the phrase "when the second battery cell is not needed to power the vehicle, the electrolyte flow device draws the electrolyte from the second individual battery cell to the reservoir" includes: When the second battery cell is in a charging state, after the electrolyte flow device receives the instruction from the power vehicle to activate the first operating mode, it determines whether the second battery cell is charged to a level greater than or equal to the first SOC threshold. If so, the electrolyte flow device performs the step of drawing the electrolyte from the second individual battery cell to the reservoir. In the first operating mode, only the first battery cell supplies power to the power vehicle.

9. The management method as described in claim 8, characterized in that, Also includes: When the power vehicle receives a switching command to switch from the first operating mode to the second operating mode, the electrolyte flow device injects the electrolyte back into the second single cell, thereby switching the power vehicle from the first operating mode to the second operating mode. In the second operating mode, the first battery unit and the second battery unit supply power to the vehicle.

10. The management method as described in claim 8, characterized in that, The electrolyte flow device includes a central processing unit and a power mechanism. The power mechanism is connected between the reservoir and each of the second individual cells. Each of the second individual cells is equipped with a solenoid valve on the connection pipe between the power mechanism and the second individual cell. The electrolyte flow device draws electrolyte from the second individual cell to the reservoir, comprising: the central processing unit controlling the power mechanism and the solenoid valve to open, so as to draw electrolyte from the second individual cell to the reservoir.

11. The management method as described in claim 9, characterized in that, The electrolyte flow device includes a central processing unit and a power mechanism. The power mechanism is connected between the reservoir and each of the second individual cells. Each of the second individual cells is equipped with a solenoid valve on the connection pipe between the power mechanism and the second individual cell. The electrolyte flow device for injecting electrolyte back into the second single cell includes: the central processing unit controlling the power mechanism and the solenoid valve to open, so as to inject electrolyte in the reservoir back into the second single cell.

12. The management method as described in claim 8, characterized in that, The electrolyte circulation device further includes a central processing unit and a power mechanism. The power mechanism includes a liquid extraction pump and a liquid injection pump. The power mechanism pipeline connects the reservoir and each of the second individual cells. Each of the second individual cells is connected to the liquid extraction pump through a liquid extraction pipeline, and each of the second individual cells is connected to the liquid injection pump through a liquid injection pipeline. Each liquid extraction pipeline is equipped with a liquid extraction valve, and each liquid injection pipeline is equipped with a liquid injection valve. The electrolyte flow device for drawing electrolyte from the second individual cell to the reservoir includes: the central processing unit controlling the opening of the pump and the valve to draw electrolyte from the second individual cell to the reservoir.

13. The management method as described in claim 9, characterized in that, The electrolyte circulation device further includes a central processing unit and a power mechanism. The power mechanism includes a liquid extraction pump and a liquid injection pump. The power mechanism pipeline connects the reservoir and each of the second individual cells. Each of the second individual cells is connected to the liquid extraction pump through a liquid extraction pipeline, and each of the second individual cells is connected to the liquid injection pump through a liquid injection pipeline. Each liquid extraction pipeline is equipped with a liquid extraction valve, and each liquid injection pipeline is equipped with a liquid injection valve. The electrolyte flow device for injecting electrolyte back into the second single cell includes: the central processing unit controlling the injection pump and the injection valve to open, so as to inject the electrolyte in the reservoir back into the second single cell.

14. A powered vehicle, characterized in that, It has a battery system as described in any one of claims 1-7.

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