Battery and electric apparatus

Abstract

The present disclosure relates to the technical field of batteries. Provided are a battery and an electric apparatus. The battery comprises a first battery cell and a second battery cell, wherein a thermal runaway temperature of the second battery cell is not greater than 180°C, a thermal runaway temperature of the first battery cell is not less than 220°C, and the second battery cell and the first battery cell are stacked in a first direction to serve as components of a cell unit. The thermal runaway temperature of the first battery cell is higher than the thermal runaway temperature of the second battery cell, and the safety of the first battery cell is higher than that of the second battery cell. The cell unit comprises the second battery cell and the first battery cell which are of different types.

Description

Battery and electric device

[0001] Cross-reference to related applications

[0002] The present disclosure is based on and claims priority to Chinese Patent Application No. 202410992893.6, filed on July 23, 2024, entitled “Battery and electric device”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of batteries, and in particular to a battery and an electric device. BACKGROUND

[0004] Batteries are increasingly widely used in life and production. For example, new energy vehicles equipped with batteries have been widely used, and batteries can be used to provide all or part of power for new energy vehicles.

[0005] In related technologies, if the battery cell of a battery experiences thermal runaway, heat spread is likely to occur, leading to battery failure and affecting the safety of the battery. SUMMARY

[0006] In view of this, the embodiments of the present disclosure aim to provide a battery and an electric device that can improve the safety performance of the battery.

[0007] To achieve the above-mentioned purpose, the technical solutions of the embodiments of the present disclosure are as follows:

[0008] The first aspect of the embodiments of the present disclosure provides a battery, comprising:

[0009] a first battery cell, the thermal runaway temperature of the first battery cell being not less than 220℃

[0010] a second battery cell, the thermal runaway temperature of the second battery cell being not greater than 180℃, and the first battery cell and the second battery cell being stacked along a first direction to serve as a component part of a monomer unit.

[0011] The battery provided by the embodiments of the present disclosure has a first battery monomer with a higher thermal runaway temperature than a second battery monomer, and the first battery monomer has higher safety than the second battery monomer. The monomer unit includes the second battery monomer and the first battery monomer, the second battery monomer can be used to improve the energy density of the battery, and the first battery monomer can be used as a safety cell. In the case of thermal runaway of the second battery monomer, the first battery monomer can isolate the second battery monomer, block the spread of heat, reduce the risk of heat spread, and improve the safety performance of the battery. Using the first battery monomer as a heat insulation structure can also reduce the amount of heat insulation structure used and improve the utilization rate of the space in the box. The combination of the second battery monomer and the first battery monomer can meet the safety requirements and energy density requirements.

[0012] In some embodiments, the DSC heat production of the negative electrode sheet of the first battery monomer is 300 J / g-1200 J / g, and the DSC heat production of the negative electrode sheet of the second battery monomer is 1500 J / g-3000 J / g.

[0013] In this embodiment, the DSC heat production of the first battery monomer is relatively low, the heat release energy is small, and the safety is good. The second battery monomer can be used to meet the high energy density and low cost requirements of the battery.

[0014] In some embodiments, in any one monomer unit, the ratio of the number of second battery monomers to the number of first battery monomers is 1:2 to 5:1.

[0015] In this embodiment, the second battery monomer can save production costs, the total heat generated by all second battery monomers in the monomer unit can be controlled, the unit heat production of the monomer unit is relatively small, the number of first battery monomers can improve the reliability of suppressing heat spread, reduce the amount of heat insulation structure such as heat insulation pad, save heat insulation structure such as heat insulation pad, and improve the battery capacity.

[0016] In some embodiments, the second battery monomer is a lithium ion battery monomer or a lithium metal battery monomer.

[0017] In this embodiment, the lithium ion battery monomer and the lithium metal battery monomer are both battery monomers that rely on lithium ions to move back and forth between the positive and negative electrodes to achieve charging and discharging. The lithium metal battery monomer uses lithium metal as the negative active layer, which can be generated after the first charging and discharging. The lithium ion battery monomer and the lithium metal battery monomer have the characteristics of low production cost and relatively large energy density.

[0018] In some embodiments, the second battery monomer includes a positive active material layer, and the material of the positive active material layer includes at least one of nickel-cobalt-manganese ternary material, lithium manganate, iron lithium phosphate, and manganese iron lithium phosphate.

[0019] In this embodiment, the material cost of the positive active material layer is relatively low, and the energy density is relatively high.

[0020] In some embodiments, in the monomer unit, the first battery monomer and the second battery monomer are arranged alternately along the first direction.

[0021] In this embodiment, one first battery monomer is arranged between two adjacent second battery monomers in the first direction. In this way, the entire monomer unit can not use a thermal insulation pad, and the space in the box can be used to a greater extent, thereby improving the energy density of the battery.

[0022] In some embodiments, the monomer unit includes a thermal insulation pad and at least two second battery monomers, and at least one thermal insulation pad is arranged between two adjacent second battery monomers.

[0023] In this embodiment, the heat transfer between two adjacent second battery monomers can be blocked or delayed by the thermal insulation pad, thereby achieving the effect of inhibiting heat spread between the plurality of battery cells.

[0024] In some embodiments, the first battery monomer includes:

[0025] a shell;

[0026] an electrode assembly located in the shell, the electrode assembly including a negative electrode sheet, a positive electrode sheet, and a separator film, at least one separator film being arranged between adjacent positive electrode sheets and negative electrode sheets, the negative electrode sheet including a negative electrode current collector and a negative electrode active layer, the negative electrode current collector being provided with the negative electrode active layer on at least one surface in the thickness direction, and the melting point of the negative electrode active layer being lower than the heat shrinkage temperature of the separator film.

[0027] In this embodiment, the melting point of the negative electrode active layer is lower than the heat shrinkage temperature of the separator film. In this way, when the temperature in the shell rises, the temperature in the shell will first reach the melting point of the negative electrode active layer due to the relatively low melting point of the negative electrode active layer, causing the local melting of the negative electrode active layer and the separation of the local melting of the negative electrode active layer from the negative electrode sheet to become a separator. The separator changes the originally complete negative electrode active material into a scattered point-like distribution, and cannot form a continuous heat conductor, so that heat cannot spread quickly to the remaining negative electrode active layer of the negative electrode sheet in a solid contact manner. That is, the local melting of the negative electrode sheet inhibits the continuous heat spread on the negative electrode sheet. In addition, the negative electrode active layer absorbs heat during melting, which can delay or inhibit the continuous rise of the temperature in the shell to a certain extent, thereby breaking the continuous heat spread inside. The local phase change of the negative electrode active layer can inhibit the rise of the temperature in the shell. In this way, the temperature in the shell is lower than the heat shrinkage temperature of the separator film, that is, the separator film basically does not undergo heat shrinkage, thereby reducing the risk of contact short circuit of the positive electrode sheet and the negative electrode sheet, achieving the self-protection and blocking effect, inhibiting heat spread, and improving the safety performance of the first battery monomer.

[0028] In some embodiments, the negative active layer is deposited on at least one surface of the negative current collector along the thickness direction after the first battery cell is charged.

[0029] In this embodiment, since the negative electrode sheet does not have negative active material before being charged, the mass of the negative electrode sheet is reduced, and the energy density of the first battery cell is improved. The surface of the negative electrode sheet is substantially free of active material before the first charge and discharge, improving the safety during the battery production and assembly process.

[0030] In some embodiments, the material of the negative active layer includes at least one of sodium metal and potassium metal.

[0031] In this embodiment, the melting point of sodium metal and the melting point of potassium metal are both lower than 100°C, and they also have good energy storage density.

[0032] In some embodiments, the surface of the negative current collector is divided into at least two partition regions, and the negative active layer is in the partition regions.

[0033] In this embodiment, the negative active layer is divided into multiple small units. In the case that the temperature of the negative electrode sheet locally rises to become an out-of-control failure point and the negative active layer in part of the partition regions melts, heat transfer can be slowed down or inhibited to a certain extent to avoid affecting the negative active layer in other partition regions and reduce the risk of heat spreading.

[0034] In some embodiments, the negative electrode sheet includes a support structure, and the support structure is arranged on at least one surface of the negative current collector along the thickness direction, and the support structure divides the surface of the negative current collector into at least two partition regions.

[0035] In this embodiment, on the one hand, the support structure can strengthen the structural strength of the negative current collector, and the support structure can be supported between the negative current collector and the remaining structural layers to play a role of interlayer support. On the other hand, the support structure divides the surface of the negative current collector into at least two partition regions, and the negative active layer is in the partition regions. In this way, the negative active layer is divided into multiple small units. In the case that the temperature of the negative electrode sheet locally rises to become an out-of-control failure point and the negative active layer in part of the partition regions melts, the support structure can inhibit the further transfer of heat and reduce the risk of heat spreading.

[0036] In some embodiments, the support structure is printed or etched on the negative current collector.

[0037] In this embodiment, both the printing process and the etching process are relatively mature, and the manufacturing cost is relatively low, and the yield of the support structure is high.

[0038] In some embodiments, the support structure includes at least two support strips, and at least part of the support strips form a closed area.

[0039] In this embodiment, the partition areas are closed areas, which can block the heat transfer between the partition areas as much as possible.

[0040] In some embodiments, the support structure comprises a first support strip and a second support strip, and the first support strip and the second support strip intersect.

[0041] In this embodiment, the first support strip and the second support strip can divide the surface of the negative current collector into more partition areas.

[0042] In some embodiments, the negative electrode sheet comprises a conductive layer, and the conductive layer is located between the negative current collector and the support structure in the thickness direction of the negative current collector.

[0043] In this embodiment, the conductive layer has the function of conducting electricity and provides electron conduction. The conductive layer can also play the role of interface modification, improve the morphology of the negative active layer forming, and make the negative active layer more dense.

[0044] In some embodiments, the first battery monomer comprises a fire-retardant member in the shell, and the fire-retardant member is arranged on at least one surface of the separator film in the thickness direction.

[0045] In this embodiment, the fire-retardant member can play the function of stopping, delaying or terminating the spread of fire, and inhibit the continuous occurrence of thermal runaway.

[0046] In some embodiments, the fire-retardant member comprises a wrapping shell and a fire-retardant agent, the fire-retardant agent is contained in the wrapping shell, and the melting point of the wrapping shell is less than the heat shrinkage temperature of the separator film.

[0047] In this embodiment, the fire-retardant agent is wrapped by the wrapping shell, and the fire-retardant agent will not be released under normal conditions of the first battery monomer; in the case of thermal runaway of the first battery monomer and temperature rise in the shell, since the melting point of the wrapping shell is less than the heat shrinkage temperature of the separator film, the temperature in the shell will first reach the melting point of the wrapping shell, and the local melting of the wrapping shell will produce a gap, and the fire-retardant agent can be released from the gap into the shell, playing the function of stopping, delaying or terminating the spread of fire, and inhibiting the continuous occurrence of thermal runaway.

[0048] In some embodiments, the fire-retardant member covers both surfaces of the separator film in the thickness direction.

[0049] In this embodiment, the fire-retardant member laid on the surface of the separator film in the thickness direction forms a fire-retardant layer. Such design has better fire-retardant effect.

[0050] In some embodiments, the first battery monomer comprises an insulating and heat-insulating member in the shell, and the insulating and heat-insulating member is arranged on at least one side of at least one electrode assembly in the thickness direction, and the melting point of the insulating and heat-insulating member is less than the heat shrinkage temperature of the separator film.

[0051] In one aspect, the insulating and heat-insulating member can bind the electrode assembly, reducing or even eliminating the probability of the electrode assembly moving in the housing. In another aspect, in the event of thermal runaway in the first battery cell, the insulating and heat-insulating member melts and flows into the electrode assembly, for example, the liquid-phase insulating and heat-insulating member covers the surface of the negative electrode tab to form an insulating barrier, further isolating the positive electrode tab and the negative electrode tab to avoid the risk of short circuit to some extent.

[0052] In some embodiments, the material of the insulating and heat-insulating member includes at least one of paraffin, polyethylene, polymethyl acrylate, polyethylene terephthalate, polytetrafluoroethylene, and melamine.

[0053] In this embodiment, after the temperature in the housing rises to the melting point of the above-mentioned material, the above-mentioned material melts and penetrates into the electrode assembly, forming a non-conductive barrier on the surface of the positive electrode tab and / or the surface of the negative electrode tab.

[0054] In some embodiments, the amount of oxygen released by the positive electrode tab is not more than 0.5wt% of the mass of the positive electrode active layer of the positive electrode tab.

[0055] In this embodiment, the lower the oxygen release amount of the positive electrode tab, the less oxygen is released by the positive electrode tab. In the event of thermal runaway of the battery, there is a lack of sufficient oxygen to assist combustion in the housing, thereby avoiding the occurrence of open fire or heat spread in the housing to some extent, and slowing down the failure as much as possible.

[0056] In some embodiments, the positive electrode tab includes a positive electrode active layer, and the material of the positive electrode active layer includes at least one of polyanion, prussian, and modified materials of each of the above-mentioned materials.

[0057] In this embodiment, the material of the positive electrode active layer includes at least one of polyanion, prussian, modified polyanion, and modified prussian. These materials have the characteristics of low oxygen release amount or no oxygen release.

[0058] In some embodiments, the material of the positive electrode active layer includes at least one of NaFePO4, NaMnPO4, NaCoPO4, Na4Fe3(PO4)2O7, Na3V2(PO4)2F3, Na3V2(PO4)3, Prussian blue, Prussian white, and modified materials of each of the above-mentioned materials.

[0059] In this embodiment, the above-mentioned material of the positive electrode active layer has the characteristics of low oxygen release amount or no oxygen release, and the oxygen release amount is not more than 0.5wt%.

[0060] The second aspect of the embodiments of the present disclosure provides an electric device, including the above-mentioned battery for providing electric energy.

[0061] The power utilization device provided by the embodiments of the present disclosure comprises the battery of the present disclosure, and has the same or corresponding beneficial effects as the battery. BRIEF DESCRIPTION OF DRAWINGS

[0062] FIG. 1 is a structural schematic diagram of a first battery monomer in an embodiment of the present disclosure;

[0063] FIG. 2 is a structural schematic diagram of a negative current collector and a first support structure in an embodiment of the present disclosure;

[0064] FIG. 3 is a structural schematic diagram of a negative current collector and a second support structure in an embodiment of the present disclosure;

[0065] FIG. 4 is a structural schematic diagram of a negative current collector and a third support structure in an embodiment of the present disclosure;

[0066] FIG. 5 is a structural schematic diagram of a first electrode assembly and an insulating and heat-insulating member in an embodiment of the present disclosure;

[0067] FIG. 6 is a structural schematic diagram of a second electrode assembly and an insulating and heat-insulating member in an embodiment of the present disclosure;

[0068] FIG. 7 is a structural schematic diagram of a first monomer unit in an embodiment of the present disclosure;

[0069] FIG. 8 is a structural schematic diagram of a second monomer unit in an embodiment of the present disclosure;

[0070] FIG. 9 is a structural schematic diagram of a third monomer unit in an embodiment of the present disclosure;

[0071] FIG. 10 is a sectional schematic diagram of a fire-retardant member in an embodiment of the present disclosure;

[0072] FIG. 11 is a structural schematic diagram of a vehicle in an embodiment of the present disclosure.

[0073] The reference signs in the drawings represent the following: vehicle 1000; battery 100; controller 200; motor 300; monomer unit 10; first battery monomer 1; shell 11; electrode assembly 12; negative current collector 121; partition area 121a; support structure 122; first support strip 1221; second support strip 1222; fire-retardant member 13; wrapping shell 131; fire-retardant agent 132; insulating and heat-insulating member 14; second battery monomer 2; heat-insulating pad 3. DETAILED DESCRIPTION

[0074] The embodiments of the technical solutions of the present disclosure will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present disclosure, and therefore only serve as examples, and cannot limit the protection scope of the present disclosure.

[0075] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure.

[0076] In the description of the embodiments of the present disclosure, the technical terms "first", "second" and the like are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the technical features indicated.

[0077] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the disclosure. The occurrence of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to each other. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0078] It should be noted that in the present disclosure, the first direction, the second direction and the third direction are perpendicular to each other, and together constitute a three-dimensional perpendicular coordinate system. At least two includes two and more than two. A plurality of includes two and more than two. The unit "℃" is Celsius. The unit "μm" is micrometer. The unit "K / min" is Kelvin per minute. The unit "℃ / s" is Celsius per second. The unit "s" is second. The unit "℃ / min" is Celsius per minute.

[0079] In the related art, when one battery cell in the battery experiences thermal runaway, it is easy to spread to other battery cells that do not experience thermal runaway, and eventually may cause all battery cells to experience thermal runaway, causing the risk of the battery catching fire. In the case of a battery used in a vehicle, it may cause the vehicle to catch fire, posing a safety risk. In some cases, when the separator in the battery cell shrinks due to heat, the positive plate and the negative plate of the battery cell are in contact and short-circuit, and the battery cell is prone to thermal runaway under internal short-circuit, overheating and other failure conditions. In some cases, the active material of the positive plate of the battery cell releases oxygen at high temperature, causing the introduction of a combustible agent into the originally sealed shell of the battery cell under failure conditions, intensifying the entire reaction, and the heat spread in the battery cell continues to occur under the conditions of the negative plate and the electrolyte in the battery cell igniting.

[0080] In the embodiments of the present disclosure, the battery includes a second battery cell and a first battery cell. The thermal runaway temperature of the second battery cell is not greater than 180℃. The thermal runaway temperature of the first battery cell is not less than 220℃. The first battery cell and the second battery cell are stacked along a first direction to serve as a component of a monomer unit.

[0081] The battery provided by the embodiments of the present disclosure has a first battery cell with a higher thermal runaway temperature than a second battery cell, and the first battery cell has higher safety than the second battery cell. The cell unit includes the second battery cell and the first battery cell, the second battery cell can be used to improve the energy density of the battery, and the first battery cell can be used as a safety cell. In the case of thermal runaway of the second battery cell, the first battery cell can isolate the second battery cell, block the spread of heat, reduce the risk of heat spread, and improve the safety performance of the battery. Using the first battery cell as a heat insulation structure can also reduce the amount of heat insulation structure used and improve the utilization rate of the space inside the box. The combination of the second battery cell and the first battery cell can meet the safety requirements and energy density requirements.

[0082] In some embodiments, the battery 100 includes a box, and the cell unit 10 is located in the box. The box can protect the cell unit 10 from liquid or other foreign matter affecting the charging and discharging of the first battery cell 1 and the second battery cell 2.

[0083] For example, the box can be a sealed box, which has more reliable dustproof and waterproof performance, and thus can be applied to scenes with more severe, humid, or even submerged use environments.

[0084] Referring to FIG. 11, the embodiments of the present disclosure also provide a power utilization device, which includes the battery 100 of any one of the embodiments of the present disclosure for providing electric energy.

[0085] The power utilization device includes, but is not limited to, an energy storage device, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, or a spacecraft, etc. The electric toy can include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric plane toy, etc. The spacecraft can include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0086] In the following embodiments, for the convenience of description, the power utilization device of an embodiment of the present disclosure is taken as a vehicle 1000 for example. The following will be described with reference to the accompanying drawings.

[0087] FIG. 11 is a structural schematic diagram of a vehicle 1000 according to some embodiments of the present disclosure. The vehicle 1000 can be a fuel automobile, a gas automobile, or a new energy automobile, which can be a pure electric vehicle, a hybrid electric vehicle, or a range extended electric vehicle, etc. As shown in FIG. 11, the vehicle 1000 is internally provided with a battery 100, which can be arranged at the bottom of the vehicle 1000 or at the front or rear of the vehicle 1000. The battery 100 can be used for power supply of the vehicle 1000, for example, the battery 100 can be used as an operating power source of the vehicle 1000. The vehicle 1000 can further include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to supply power to the motor 300, for example, to meet the power demand of the vehicle 1000 during starting, navigation, and driving.

[0088] In some embodiments of the present disclosure, the battery 100 can not only be used as an operating power source of the vehicle 1000, but also be used as a driving power source of the vehicle 1000, to replace or partially replace fuel or natural gas to provide driving power for the vehicle 1000.

[0089] Referring to FIGS. 1, 7, 8, 9, and 11, the present disclosure provides a battery 100, which includes a second battery monomer 2 and a first battery monomer 1. The thermal runaway temperature of the second battery monomer 2 is not greater than 180℃. The thermal runaway temperature of the first battery monomer 1 is not less than 220℃. The second battery monomer 2 and the first battery monomer 1 are stacked along a first direction to serve as components of a monomer unit.

[0090] The thermal runaway temperature refers to a temperature at which the temperature rising rate of the battery cell is not less than 60℃ / min.

[0091] The thermal runaway temperature of the second battery monomer 2 is not greater than 180℃. For example, the thermal runaway temperature of the second battery monomer 2 can be 180℃, 170℃, or 160℃, etc.

[0092] The thermal runaway temperature of the first battery monomer 1 is not less than 220℃. For example, the thermal runaway temperature of the first battery monomer can be 220℃, 230℃, or 250℃, etc.

[0093] The second battery monomer 2 and the first battery monomer 1 are stacked along a first direction, which means that the large face of the second battery monomer 2 and the large face of the first battery monomer 1 both intersect with the first direction, and the large face of the second battery monomer 2 and the large face of the first battery monomer 1 are substantially parallel. For example, the large face of the first battery monomer 1 is perpendicular to the first direction, and the large face of the second battery monomer 2 is perpendicular to the first direction. For example, the first direction can be consistent with the thickness direction of the negative current collector 121 of the first battery monomer 1.

[0094] The battery provided by the embodiments of the present disclosure has a higher thermal runaway temperature of the first battery monomer 1 than a thermal runaway temperature of the second battery monomer 2, and the first battery monomer 1 has a higher safety than the second battery monomer 2. The monomer unit 10 includes the second battery monomer 2 and the first battery monomer 1 of different types. The second battery monomer 2 can be used to improve the energy density of the battery 100, and the first battery monomer 1 can be used as a safety cell. In the case of thermal runaway of the second battery monomer 2, the first battery monomer 1 can isolate the second battery monomer 2, block the spread of heat, reduce the risk of heat spread, and improve the safety performance of the battery 100. Using the first battery monomer 1 as a heat insulation structure can also reduce the amount of heat insulation structure used and improve the utilization rate of the space in the box. The combination of the second battery monomer 2 and the first battery monomer 1 can meet the safety requirements and energy density requirements.

[0095] It can be understood that the second battery monomer 2 and the first battery monomer 1 are both battery monomers, also known as cells.

[0096] The thermal runaway temperature can be tested by a method known in the art. For example, the thermal runaway temperature can be tested by an Accelerating Rate Calorimeter (ARC test). The test conditions are as follows: during the experiment, the prepared sample and container are heated to a pre-set initial temperature under adiabatic conditions, and a certain standby time (usually 5-10 minutes) is allowed to reach thermal equilibrium, and then the self-reaction heat release rate is observed to see if it exceeds the set value (usually set to 0.02℃ / min). If no heat release is detected, the temperature of the sample is increased by one step, usually 5-10℃, and the heat release is checked again after a standby time (usually 5-10 minutes). The same steps are repeated several times, and once the heat release is detected, the experimental system automatically enters strict adiabatic control, and records the time, temperature, heat release rate and pressure data at regular time intervals. The temperature at which the temperature rise rate of the cell is not less than 60℃ / min is the thermal runaway temperature.

[0097] In some embodiments, the DSC heat production of the negative electrode sheet of the first battery monomer 1 is 300J / g-1200J / g, and the DSC heat production of the negative electrode sheet of the second battery monomer 2 is 1500J / g-3000J / g. In this way, the DSC heat production of the first battery monomer 1 is relatively low, the heat release energy is small, and the safety is good. The second battery monomer 2 can be used to meet the high energy density and low cost requirements of the battery.

[0098] It should be noted that the unit J / g refers to joules per gram. DSC refers to differential scanning calorimetry. The DSC heat generation refers to the DSC heat release of the negative electrode active layer of the unit mass under a nitrogen atmosphere at 50°C to 500°C.

[0099] It can be understood that the DSC heat generation of the negative electrode tab of the first battery cell 1 and the DSC heat generation of the negative electrode tab of the second battery cell 2 are defined in the same way and can be measured by the same method. The DSC heat generation of the negative electrode tab of the first battery cell 1 is taken as an example below. By disassembling the negative electrode tab of the battery cell in the fully charged state, the DSC heat generation at the tab level is tested, so as to compare the heat release and serve as evidence of the safety capability of the battery cell. The method known in the art can be used for measurement. The DSC heat generation can be measured by referring to the national standard document GB / T 13464-2008. As an example, the DSC heat generation can be tested by the following method:

[0100] Test conditions: test equipment model: NETZSCH STA 449F3; sample: negative electrode tab is punched into a small disc with a diameter of 5mm (the negative electrode tab includes the negative electrode active layer and the current collector, and the mass of the current collector needs to be deducted when calculating the heat release of the unit mass); 2uL (microliters) of electrolyte is added on the negative electrode tab; the test starting temperature is room temperature, for example, 25°C; the temperature rising rate is 10K / min (kelvin per minute); the test atmosphere is nitrogen; and the sample preparation environment is a glove box.

[0101] Post-test data standard processing: the ordinate of the DSC test result is the heat flow, with the unit of mW / mg (milliwatt per milligram), and the abscissa is the temperature, with the unit of °C. The test data needs to be deducted from the baseline of the empty crucible test result; the horizontal adjustment is made from 50°C to the end temperature, and the DSC heat release of the test sample in the range of 50°C to 500°C under a nitrogen atmosphere is obtained by fitting calculation.

[0102] In an embodiment, referring to FIGS. 7 to 9, the single unit 10 includes the thermal insulation pad 3 and at least two second battery cells 2, and at least one thermal insulation pad 3 is arranged between adjacent two second battery cells 2.

[0103] For example, in an embodiment, one thermal insulation pad 3 is arranged between adjacent two second battery cells 2. In an embodiment, two or more thermal insulation pads 3 are arranged between adjacent two second battery cells 2.

[0104] In this embodiment, the heat transfer between adjacent two second battery cells 2 can be blocked or delayed by the thermal insulation pad 3, so as to achieve the effect of inhibiting the heat spread between multiple battery cells.

[0105] In one embodiment, in the single unit 10, all the second battery cells 2 are arranged in sequence along the first direction as components of the battery pack, and at least one first battery cell 1 is arranged at each end of the battery pack along the first direction. A thermal insulation pad 3 is arranged between any two adjacent second battery cells 2. The first battery cell 1 has higher safety, and the heat transfer between the battery cell and the box can be reduced.

[0106] In one embodiment, referring to FIG. 7, the single unit 10 includes 5 second battery cells 2 and 1 first battery cell 1, and the 5 second battery cells 2 are arranged in sequence, and a thermal insulation pad 3 is arranged between any two adjacent second battery cells 2. No thermal insulation pad 3 is arranged between the adjacent second battery cell 2 and the first battery cell 1. In this way, the whole single unit 10 can use four thermal insulation pads 3. In this way, the utilization of the space in the box can be improved, and more battery cells can be placed without increasing the space in the box, thereby improving the energy density.

[0107] In one embodiment, referring to FIG. 8, the single unit 10 includes 3 second battery cells 2 and 2 first battery cells 1, and the 3 second battery cells 2 are arranged in sequence, one of the first battery cells 1 is arranged between any two adjacent second battery cells 2, and the other first battery cell 1 is arranged at any end of the single unit 10 along the first direction. A thermal insulation pad 3 is arranged between any two adjacent second battery cells 2. No thermal insulation pad 3 is arranged between the adjacent second battery cell 2 and the first battery cell 1. In this way, the whole single unit 10 can use only one thermal insulation pad 3.

[0108] In one embodiment, in the single unit 10, the first battery cells 1 and the second battery cells 2 are arranged alternately along the first direction. That is, one first battery cell 1 is arranged between any two adjacent second battery cells 2 along the first direction. In this way, the whole single unit 10 can not use the thermal insulation pad 3, and the space in the box can be used to a greater extent, thereby improving the energy density of the battery.

[0109] In one embodiment, referring to FIG. 9, the single unit 10 includes 2 second battery cells 2 and 3 first battery cells 1, and the 3 first battery cells 1 are arranged in sequence, and one second battery cell 2 is arranged between any two adjacent first battery cells 1. No thermal insulation pad 3 is arranged between the adjacent second battery cell 2 and the first battery cell 1. In this way, the whole single unit 10 can not use the thermal insulation pad 3.

[0110] In one embodiment, the ratio of the number of the second battery cells 2 to the number of the first battery cells 1 in any one monobloc unit 10 is from 1:2 to 5:1. In some embodiments, the ratio of the number of the second battery cells 2 to the number of the first battery cells 1 is from 1:2 to 4:3. For example, the ratio of the number of the second battery cells 2 to the number of the first battery cells 1 is 1:2, 3:1, 4:3, or 5:1, etc.

[0111] In one embodiment, the ratio of the number of the second battery cells 2 to the number of the first battery cells 1 is 1:1, and the second battery cells 2 and the first battery cells 1 are arranged alternately along the first direction. No thermal insulation pad 3 is arranged between adjacent second battery cells 2 and first battery cells 1. In this way, the monobloc unit 10 can be free of the thermal insulation pad 3, and the structure is more compact. More second battery cells 2 and first battery cells 1 can be arranged in the case, and the capacity of the battery 100 is improved.

[0112] In this embodiment, the second battery cells 2 can save production cost by using the above ratio. The total heat generated by all the second battery cells 2 in the monobloc unit 10 can be controlled, and the unit heat generated by the monobloc unit 10 is relatively small. The number of the first battery cells 1 can improve the reliability of suppressing heat spread, and the amount of the thermal insulation structure such as the thermal insulation pad 3 can be reduced. The thermal insulation structure such as the thermal insulation pad 3 can be saved, and the capacity of the battery 100 can be improved.

[0113] In some embodiments, the thermal insulation pad 3 can have a substantially flat structure.

[0114] In some embodiments, the thickness of each thermal insulation pad 3 is equal.

[0115] In some embodiments, the thickness of at least two thermal insulation pads 3 is not equal. For example, the number of the thermal insulation pads 3 is three, the thickness of two thermal insulation pads 3 is equal, and the thickness of the other thermal insulation pad 3 is not equal.

[0116] In one embodiment, the second battery cell 2 is a lithium ion battery cell or a lithium metal battery cell.

[0117] In this embodiment, the lithium ion battery cell and the lithium metal battery cell are battery cells that realize charging and discharging by relying on lithium ions to embed and de-embed between the positive and negative electrodes. The lithium metal battery cell uses lithium metal as the negative active layer, which can be generated after the first charging and discharging. The lithium ion battery cell and the lithium metal battery cell have the characteristics of low production cost and relatively large energy density.

[0118] In an embodiment, the second battery cell 2 comprises a positive electrode active material layer, and a material of the positive electrode active material layer comprises at least one of a nickel-cobalt-manganese ternary material, lithium manganate, lithium iron phosphate, and lithium manganese iron phosphate. The above-mentioned materials have relatively low cost and relatively high energy density. The nickel-cobalt-manganese ternary material can be lithium nickel-cobalt-manganese oxide.

[0119] For example, the nickel-cobalt-manganese ternary material can be a high-nickel ternary material or a medium-low-nickel ternary material.

[0120] The high-nickel ternary material can be a ternary material in which the ratio of the content of nickel to the total mass of the positive electrode active material layer is not less than 80%.

[0121] The medium-low-nickel ternary material can be a ternary material in which the ratio of the content of nickel to the total mass of the positive electrode active material layer is less than 80%.

[0122] In an embodiment, referring to FIGS. 1-5, the first battery cell 1 comprises a housing 11 and an electrode assembly 12.

[0123] Referring to FIGS. 1-5, the electrode assembly 12 is located in the housing 11, and the electrode assembly 12 comprises a negative electrode sheet, a positive electrode sheet, and a separator film. At least one separator film is arranged between adjacent positive electrode sheets and negative electrode sheets. The negative electrode sheet comprises a negative electrode current collector 121 and a negative electrode active layer. The negative electrode current collector 121 is provided with the negative electrode active layer on at least one surface in the thickness direction. The melting point of the negative electrode active layer is lower than the heat shrinkage temperature of the separator film.

[0124] The electrode assembly 12 is an energy storage structure of the first battery cell 1.

[0125] At least one separator film is arranged between adjacent positive electrode sheets and negative electrode sheets. The separator film arranged between the positive electrode sheet and the negative electrode sheet can prevent short circuiting.

[0126] For example, the negative electrode current collector 121 has two opposite surfaces in the thickness direction thereof. The negative electrode current collector 121 is provided with the negative electrode active layer on either one or both of the two opposite surfaces in the thickness direction. In an embodiment, the negative electrode current collector 121 is provided with the negative electrode active layer on one surface in the thickness direction. In another embodiment, the negative electrode current collector 121 is provided with the negative electrode active layer on both surfaces in the thickness direction.

[0127] The melting point of the negative electrode active layer refers to the temperature at which the negative electrode active layer changes from a solid state to a liquid state.

[0128] The heat shrinkage temperature of the separator film refers to the temperature at which the separator film shrinks under heat.

[0129] The first battery monomer 1 provided by the embodiments of the present disclosure is designed in such a way that the melting point of the negative active layer is lower than the heat shrinkage temperature of the isolation film. In the case of temperature rise in the shell 11, due to the relatively low melting point of the negative active layer, the temperature in the shell 11 will first reach the melting point of the negative active layer, so that the local melting of the negative active layer will occur first, and the local melting of the negative active layer will separate from the negative plate to become a separator. The originally complete negative active material will become a scattered point-like distribution, and cannot form a continuous heat conductor, so the heat cannot spread quickly to the remaining negative active layer of the negative plate in a solid contact manner. That is, the local melting of the negative plate can inhibit the continuous heat spread on the negative plate. In addition, the negative active layer will absorb heat during melting, which can delay or inhibit the continuous temperature rise in the shell 11 to some extent, so as to break the continuous heat spread. The phase change of the local negative active layer can inhibit the temperature rise in the shell 11, so that the temperature in the shell 11 will be lower than the heat shrinkage temperature of the isolation film. That is, the isolation film will not substantially shrink, which can reduce the risk of short circuit between the positive plate and the negative plate, and can play a self-protection and blocking role, inhibit heat spread, and improve the safety performance of the first battery monomer 1.

[0130] It should be noted that the melting point is a meaning known in the art, and can be measured by methods and instruments known in the art. For example, in the heat flow-temperature change diagram, the peak temperature of the DSC curve is the melting point.

[0131] It should be noted that the heat shrinkage temperature of the isolation film can be measured in the following way: a plurality of isolation film samples with a set size are placed in a vacuum oven with different set temperatures (starting from 100°C, increasing the temperature by 5°C each time), and the temperature is kept constant for 2 hours (h). The shrinkage size of the isolation film after constant temperature is tested. The number of isolation film samples is ≥5, and the maximum and minimum values are removed to reduce errors, and the average value of the remaining number of isolation film samples is calculated, for example, the arithmetic mean. Taking the number of isolation film samples as an example, the maximum and minimum values are removed to reduce errors, and the average value of the remaining 3 isolation film samples is calculated, for example, the arithmetic mean. The shrinkage size of the isolation film can be obtained by the above method, and the heat shrinkage ratios of the length direction and the width direction of the isolation film meet the set conditions, and the corresponding temperature is the heat shrinkage temperature of the isolation film. The set conditions include: the heat shrinkage ratio of the length direction reaches 5.0%, and the heat shrinkage ratio of the width direction reaches 3.0%. The heat shrinkage ratio of the length direction refers to the ratio of the shrinkage size of the length direction of the isolation film after constant temperature to the set size of the length direction. The heat shrinkage ratio of the width direction refers to the ratio of the shrinkage size of the width direction of the isolation film after constant temperature to the set size of the width direction.

[0132] In an embodiment, at least one surface of the negative current collector 121 along the thickness direction is deposited with the negative active layer after the first battery cell 1 is charged. That is, before the first charge-discharge, there is substantially no negative active layer on the negative current collector 121, and the first battery cell 1 is commonly referred to as a negative electrode-free first battery cell 1.

[0133] For example, during the charging process, the second active ions of the first battery cell 1 are combined with electrons on the surface of the negative current collector 121 to form the negative active layer through deposition. Since the negative plate has no negative active material before charging, the mass of the negative plate is reduced, and the energy density of the first battery cell 1 is improved. The surface of the negative plate has substantially no active material before the first charge-discharge, which improves the safety during the production and assembly of the battery 100.

[0134] In an embodiment, the cohesion of the liquid-phase negative active layer is relatively large at normal temperature and pressure, for example, the cohesion of the liquid-phase negative active layer is greater than the adhesion of the liquid-phase negative active layer on the surface of the separator. The normal temperature can be -20°C to 50°C, and the normal pressure can be one atmosphere. During the melting of the negative active layer, the local negative active layer is fused and separated from the negative plate, and the liquid-phase negative active layer separated from the negative plate is aggregated into a separate body, for example, the liquid-phase negative active layer separated from the negative plate is aggregated and dispersed into a block-shaped or spherical solid separate body. The liquid-phase negative active layer separated from the negative plate is substantially not infiltrated into the separator, and the aggregated separate body cannot cause heat spread in a solid contact manner on the remaining negative plate.

[0135] In an embodiment, the melting point of the negative active layer can be not greater than 100°C. The melting point of the negative active layer is less than or equal to 100°C, and the melting point of the negative active layer is relatively low. When thermal runaway occurs, the local negative active layer is fused and separated to inhibit heat spread, thereby playing a self-protection and barrier role.

[0136] In an embodiment, the material of the negative active layer can be a metal. For example, the material of the negative active layer can be a metal with a melting point not greater than 100°C.

[0137] For example, in an embodiment, the material of the negative active layer includes at least one of sodium metal and potassium metal. The melting point of sodium metal and the melting point of potassium metal are both less than 100°C, and they also have good energy storage density.

[0138] In one embodiment, the surface of the negative current collector 121 is divided into at least two sub-zones 121a, and the negative active layer is in the sub-zones 121a. In this way, the negative active layer is divided into multiple small units, and in the case that the negative active layer in part of the sub-zones 121a melts when the local temperature of the negative sheet rises to a point of uncontrolled failure, heat transfer can be slowed down or inhibited to a certain extent to avoid affecting the negative active layer in other sub-zones 121a and reduce the risk of heat spreading.

[0139] In one embodiment, the surface of the negative current collector 121 can be formed with grooves to divide it into at least two sub-zones 121a. The formation of the grooves is not limited, and for example, part of the material on the surface of the negative current collector 121 can be removed by etching to form the grooves.

[0140] In one embodiment, referring to FIGS. 2-4, the negative sheet includes a support structure 122, and the negative current collector 121 is provided with the support structure 122 on at least one surface in the thickness direction, and the support structure 122 divides the surface of the negative current collector 121 into at least two sub-zones 121a.

[0141] For example, the support structure 122 is provided on either or both of the two opposite surfaces of the negative current collector 121 in the thickness direction. In one embodiment, the support structure 122 is provided on one surface of the negative current collector 121 in the thickness direction. In another embodiment, the support structure 122 is provided on both surfaces of the negative current collector 121 in the thickness direction.

[0142] The support structure 122 can protrude from at least one surface of the negative current collector 121 in the thickness direction. That is, the support structure 122 is a structure added to at least one surface of the negative current collector 121 in the thickness direction.

[0143] In this embodiment, on the one hand, the support structure 122 can play a role in strengthening the structural strength of the negative current collector 121, and the support structure 122 can be supported between the negative current collector 121 and the remaining structure layers to play a role in interlayer support; on the other hand, the support structure 122 divides the surface of the negative current collector 121 into at least two sub-zones 121a, and the negative active layer is in the sub-zones 121a. In this way, the negative active layer is divided into multiple small units, and in the case that the negative active layer in part of the sub-zones 121a melts when the local temperature of the negative sheet rises to a point of uncontrolled failure, the support structure 122 can inhibit further heat transfer and reduce the risk of heat spreading.

[0144] In one embodiment, referring to FIGS. 2 and 3, the support structure 122 includes at least two support bars, and at least part of the support bars form the enclosed area. For example, all of the support bars can form the enclosed area. For another example, part of the support bars can form the enclosed area. In some embodiments, at least part of the support bars extend to the edge of the negative current collector 121, and the enclosed area is defined by the support bars and the edge of the negative current collector 121. In some embodiments, the support bars are connected to each other to form the enclosed area, and the enclosed area is defined by the support bars. The enclosed area formed by the partition area 121a can block the heat transfer between the partition areas as much as possible.

[0145] In one embodiment, referring to FIGS. 2 and 3, the support structure 122 includes at least two first support bars 1221 spaced apart from each other, and each of the first support bars 1221 extends in parallel. The parallel extension of each of the first support bars 1221 means that each of the first support bars 1221 is substantially parallel, so that the surface of the negative current collector 121 between any two adjacent first support bars 1221 can be a partition area 121a.

[0146] It can be understood that the support bars include the first support bars 1221, that is, the first support bars 1221 are one of the support bars. The support bars also include the second support bars 1222, that is, the second support bars 1222 are one of the support bars.

[0147] In one embodiment, the distance between any two adjacent support bars can be equal or unequal.

[0148] The extension direction of the first support bars 1221 is not limited. For example, in one embodiment, referring to FIG. 3, the first support bars 1221 extend along the length direction of the negative current collector 121. In another embodiment, the first support bars 1221 can also extend along a direction intersecting the length direction, for example, referring to FIG. 2, the first support bars 1221 extend along the width direction of the negative current collector 121.

[0149] The shape of the first support bars 1221 is not limited. The first support bars 1221 can extend along a straight line, or the first support bars 1221 can also extend along a curve.

[0150] In one embodiment, referring to FIG. 4, the support structure 122 includes the first support bars 1221 and the second support bars 1222, and the first support bars 1221 and the second support bars 1222 intersect. Specifically, the intersection of the first support bars 1221 and the second support bars 1222 is located on the surface of the negative current collector 121. In this way, the first support bars 1221 and the second support bars 1222 can divide the surface of the negative current collector 121 into more partition areas 121a.

[0151] In one embodiment, referring to FIG. 4, the at least two first support bars 1221 and the at least two second support bars 1222 are staggered to form a grid-like region. In this way, the support structure 122 is substantially in a grid-like structure, and the number of the division regions 121a is greater, and the negative active layer is divided into more individual modules with smaller areas.

[0152] It can be understood that, referring to FIG. 4, the support structure 122 is substantially in a grid-like structure, and the shape of the division region 121a is not limited. For example, the division region 121a can be polygonal, circular, elliptical, or irregularly shaped, etc. Irregularly shaped means irregularly shaped. The polygonal shape includes, but is not limited to, square or rhombus, etc.

[0153] For example, in one embodiment, referring to FIG. 4, one of the first support bars 1221 and the second support bars 1222 extends along the length direction of the negative current collector 121, and the other of the first support bars 1221 and the second support bars 1222 extends along the width direction of the negative current collector 121.

[0154] The shape of the second support bar 1222 is not limited. The second support bar 1222 can extend along a straight line, or the second support bar 1222 can also extend along a curve.

[0155] The material of the support structure 122 can be a conductive material or an insulating material. For example, the material of the support structure 122 can be resin and / or polymer such as polyacrylic acid.

[0156] The manufacturing process of the support structure 122 is not limited. The support structure 122 is formed by printing or etching on the negative current collector 121. For example, the support structure 122 can be attached to the surface of the negative current collector 121 by processes such as intaglio, 3D printing, or UV printing. Both the printing process and the etching process are relatively mature, and the manufacturing cost is relatively low, and the yield of the support structure 122 is high.

[0157] In one embodiment, the thickness of the support structure 122 can be 5 μm to 50 μm. For example, the thickness of the support structure 122 can be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 28 μm, 30 μm, 35 μm, 40 μm, 45 μm, 47 μm, or 50 μm, etc. In this way, the support structure 122 has good supportability and is basically not collapsed during the shaping process of the negative plate.

[0158] In an embodiment, the negative electrode sheet includes an electrically conductive layer, which is located between the negative current collector 121 and the support structure 122 in the thickness direction of the negative current collector 121. That is, in the thickness direction of the negative current collector 121, the negative current collector 121, the electrically conductive layer, and the support structure 122 are sequentially stacked, and the negative active layer can be located on the electrically conductive layer. The electrically conductive layer has an electrically conductive function to provide electron conduction, and can also play an interface modification role to improve the morphology of the negative active layer formation, so that the negative active layer is more compact.

[0159] The manufacturing process of the electrically conductive layer is not limited, and for example, an electrically conductive paste can be coated on the surface of the negative current collector 121 and dried to form.

[0160] It can be understood that, in the case where the electrically conductive layer is not provided on the surface of the negative current collector 121, the support structure 122 and the negative active layer can be directly provided on the surface of the negative current collector 121.

[0161] In an embodiment, referring to FIGS. 1 and 10, the first battery monomer 1 includes a flame retardant 13 located in the shell 11, and the flame retardant 13 is provided on at least one surface of the separator in the thickness direction. The flame retardant 13 can play a function of stopping, delaying, or terminating the spread of flame to inhibit the continuous occurrence of thermal runaway.

[0162] The flame retardant 13 includes a wrapping shell 131 and a flame retardant 132, and the flame retardant 132 is contained in the wrapping shell 131, and the melting point of the wrapping shell 131 is less than the heat shrinkage temperature of the separator.

[0163] The melting point of the wrapping shell 131 refers to the temperature at which the wrapping shell 131 changes from a solid state to a liquid state.

[0164] The flame retardant 132 can play a function of stopping, delaying, or terminating the spread of flame.

[0165] For example, the flame retardant 13 is provided on either one or both of the two opposite surfaces of the separator in the thickness direction. In an embodiment, the flame retardant 13 is provided on one surface of the separator in the thickness direction. In another embodiment, the flame retardant 13 is provided on both surfaces of the separator in the thickness direction.

[0166] In this embodiment, the flame retardant 132 is wrapped by the wrapping shell 131, and in the normal case of the first battery monomer 1, the flame retardant 132 will not be released; in the case where the first battery monomer 1 occurs thermal runaway and the temperature in the shell 11 rises, since the melting point of the wrapping shell 131 is less than the heat shrinkage temperature of the separator, the temperature in the shell 11 will first reach the melting point of the wrapping shell 131, and the local melting of the wrapping shell 131 will generate a gap, and the flame retardant 132 can be released into the shell 11 from the gap, playing a function of stopping, delaying, or terminating the spread of flame to inhibit the continuous occurrence of thermal runaway.

[0167] The melting point of the wrapping shell 131 can be higher than the melting point of the negative active layer. Illustratively, the melting point of the negative active layer is not greater than 100°C, and the melting point of the wrapping shell 131 can be greater than 100°C.

[0168] The appearance shape of the wrapping shell 131 is not limited, and illustratively, in an embodiment, referring to FIG. 10, the wrapping shell 131 can be substantially hollow spherical.

[0169] In an embodiment, the fire retardant 13 covers both surfaces of the separator along the thickness direction. That is, the fire retardant 13 is laid on the surfaces of the separator along the thickness direction to form a fire retardant layer. With this design, the fire retardant effect is better.

[0170] In an embodiment, the shell layer thickness of the wrapping shell 131 can be 1 μm to 10 μm. That is, the shell layer thickness of the wrapping shell 131 can be 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, or 10 μm, and the like. In the normal case of the first battery monomer 1, the strength of the wrapping shell 131 is moderate, and the fire retardant 132 can be well protected from leakage; in the case of thermal runaway of the first battery monomer 1, the melting rate of the wrapping shell 131 is moderate, and a gap can be formed relatively quickly to release the fire retardant 132.

[0171] In an embodiment, the diameter of the hollow cavity of the wrapping shell 131 can be 1 μm to 20 μm. Illustratively, the diameter of the hollow cavity of the wrapping shell 131 can be 1 μm, 5 μm, 10 μm, 14 μm, 15 μm, or 20 μm, and the like. That is, the diameter of the fire retardant 132 located in the hollow cavity can be 1 μm to 20 μm.

[0172] In an embodiment, the thickness dimension of the fire retardant layer can be 3 μm to 30 μm. Illustratively, the thickness dimension of the fire retardant layer can be 3 μm, 5 μm, 10 μm, 20 μm, or 30 μm, and the like. With this design, the mass of the fire retardant 132 can be adapted to the size of the first battery monomer 1, and the thermal runaway can be more effectively suppressed.

[0173] The material of the fire retardant 132 is not limited, and the material of the fire retardant 132 includes but is not limited to 2,4-dimethyl-6-tert-butyl phenol phosphate (abbreviated as DMTP).

[0174] The material of the wrapping shell 131 is not limited, and the material of the wrapping shell 131 includes but is not limited to Polymethyl Methacrylate (abbreviated as PMMA).

[0175] The material of the separator includes but is not limited to polypropylene (abbreviated as PP) and / or polyethylene (abbreviated as PE), and the like.

[0176] In an embodiment, the first battery monomer 1 comprises a glue layer, which is arranged between the surface of at least one of the flame-retardant member 13 and the separator along the thickness direction. That is, the glue layer is located on the side of the flame-retardant member 13 along the thickness direction close to the separator. The glue layer not only facilitates the stable adhesion of the flame-retardant member 13, but also plays a role in bonding the positive plate and the negative plate, shaping the interface of the positive plate and / or the negative plate, reducing the risk of wrinkles of the positive plate and the negative plate, and improving the processing consistency.

[0177] In an embodiment, the first battery monomer 1 comprises a composite coating layer, which is arranged on the surface of at least one of the glue layer and the separator along the thickness direction. The composite coating layer can have the functions of liquid absorption and improving the heat shrinkage resistance of the separator.

[0178] The composite coating layer can be made of an insulating inorganic material, which can also play a role in preventing micro-short circuit.

[0179] In an embodiment, the material of the composite coating layer includes, but is not limited to, at least one of ceramic and metal oxide.

[0180] In an embodiment, referring to FIGS. 1, 5 and 6, the first battery monomer 1 comprises an insulating and heat-insulating member 14 located in the shell 11, and at least one of the electrode assemblies 12 is provided with the insulating and heat-insulating member 14 along at least one side in the thickness direction, and the melting point of the insulating and heat-insulating member 14 is lower than the heat shrinkage temperature of the separator.

[0181] At least one side of the electrode assembly 12 along the thickness direction is provided with the insulating and heat-insulating member 14, that is, at least part of the insulating and heat-insulating member 14 overlaps the electrode assembly 12 in the thickness direction. For example, one side of the electrode assembly 12 along the thickness direction is provided with the insulating and heat-insulating member 14. For another example, both sides of the electrode assembly 12 along the thickness direction are provided with the insulating and heat-insulating member 14.

[0182] The melting point of the insulating and heat-insulating member 14 refers to the temperature at which the insulating and heat-insulating member 14 changes from solid to liquid.

[0183] The insulating and heat-insulating member 14 has the functions of heat insulation and insulation. The melting point of the insulating and heat-insulating member 14 is lower than the heat shrinkage temperature of the separator. Since the melting point of the insulating and heat-insulating member 14 is relatively low, the temperature in the shell 11 will first reach the melting point of the insulating and heat-insulating member 14, so that the local part of the insulating and heat-insulating member 14 will first melt, and the liquid-phase insulating and heat-insulating member 14 will flow into the electrode assembly 12 to further isolate the positive plate and the negative plate, to a certain extent, reduce the risk of contact short circuit of the positive plate and the negative plate, and inhibit heat spread.

[0184] In one aspect, the insulation and thermal barrier 14 can bind the electrode assembly 12 to reduce or even eliminate the probability of the electrode assembly 12 from moving within the housing 11. In another aspect, in the event of thermal runaway occurring in the first battery cell 1, the insulation and thermal barrier 14 can melt and flow into the electrode assembly 12, for example, the liquid insulation and thermal barrier 14 covers the surface of the negative electrode tab to form an insulating barrier, further isolating the positive electrode tab and the negative electrode tab to avoid the risk of short circuit to some extent.

[0185] In one embodiment, the insulation and thermal barrier 14 is made of at least one of paraffin, polyethylene, polymethyl acrylate, polyethylene terephthalate, polytetrafluoroethylene, and melamine. For example, when the temperature in the housing 11 rises to the melting point of the above-mentioned materials, the above-mentioned materials melt and penetrate into the electrode assembly 12 to form a non-conductive barrier on the surface of the positive electrode tab and / or the surface of the negative electrode tab.

[0186] In one embodiment, the insulation and thermal barrier 14 is made of at least one of paraffin, polyethylene, polymethyl acrylate, polyethylene terephthalate, polytetrafluoroethylene, and melamine. For example, when the temperature in the housing 11 rises to the melting point of the above-mentioned materials, the above-mentioned materials melt and penetrate into the electrode assembly 12 to form a non-conductive barrier on the surface of the positive electrode tab and / or the surface of the negative electrode tab.

[0187] In one embodiment, the total thickness of the insulation and thermal barrier 14 is 1 um to 15 um. The total thickness of the insulation and thermal barrier 14 refers to the sum of the thicknesses of all the insulation and thermal barriers 14 in one first battery cell 1. For example, the total thickness of the insulation and thermal barrier 14 is 1 um, 2 um, 3 um, 5 um, 8 um, 10 um, 12 um, 14 um, or 15 um, and the like. In this way, the thickness of the first battery cell 1 is not excessively increased to some extent.

[0188] The number of the insulation and thermal barriers 14 can be one or at least two, for example, 2, 3, 4, or 5, and the like.

[0189] In one embodiment, referring to FIG. 5, the first battery cell 1 includes 4 electrode assemblies 12 and 5 insulation and thermal barriers 14, and one electrode assembly 12 is arranged between two adjacent insulation and thermal barriers 14. For example, the total thickness of the 5 insulation and thermal barriers 14 can be 1 um to 15 um.

[0190] In one embodiment, referring to FIG. 6, the first battery cell 1 includes 4 electrode assemblies 12 and 5 insulation and thermal barriers 14, and the 5 insulation and thermal barriers 14 are stacked in the thickness direction, and the 4 electrode assemblies 12 are distributed on both sides of the 5 insulation and thermal barriers 14 in the thickness direction. For example, the total thickness of the 5 insulation and thermal barriers 14 can be 1 um to 15 um.

[0191] In one embodiment, the insulating and heat insulating member 14 can have a flat plate structure. In this way, the insulating and heat insulating member 14 with the flat plate structure is easy to form and can better fit the electrode assembly 12.

[0192] In some embodiments, the thickness of each of the insulating and heat insulating members 14 is equal.

[0193] In some embodiments, the thickness of at least two of the insulating and heat insulating members 14 is not equal. For example, the number of the insulating and heat insulating members 14 is three, in which the thickness of two of the insulating and heat insulating members 14 is equal, and the thickness of the other insulating and heat insulating member 14 is not equal.

[0194] In one embodiment, the amount of oxygen released by the positive electrode sheet is not more than 0.5wt% of the mass of the positive electrode active layer of the positive electrode sheet. For example, the amount of oxygen released by the positive electrode sheet can be 0.5wt%, 0.4wt%, or 0wt%, etc. The lower the amount of oxygen released by the positive electrode sheet, the less oxygen is released by the positive electrode sheet, so that in the case of thermal runaway of the battery 100, there is insufficient oxygen in the shell 11 to support combustion, thereby to some extent avoiding the occurrence of open fire or heat spread in the shell 11, and slowing down the degree of failure as much as possible.

[0195] The amount of oxygen released refers to the percentage of the amount of oxygen released by the positive electrode sheet to the mass of the positive electrode active layer of the positive electrode sheet.

[0196] The determination of the amount of oxygen released by the positive electrode sheet can be determined by a method known in the art. For example, the determination device can be a thermal analysis and mass spectrometry instrument, and the test method can refer to standards JYT014-1996 and GB / T 6041-2002. For example, the determination device is heated at a temperature range of 45°C to 600°C at a rate of 10K / min in an argon atmosphere, and the mass of oxygen accumulated by the determination device can be used to obtain the amount of oxygen released by the positive electrode sheet.

[0197] In one embodiment, the positive electrode sheet includes a positive electrode active layer, and the material of the positive electrode active layer includes at least one of a polyanion type, a prussian type, and a modified material of each type. That is, the material of the positive electrode active layer includes at least one of a polyanion type, a prussian type, a modified polyanion type, and a modified prussian type. These materials have the characteristics of low oxygen release or no oxygen release.

[0198] In an embodiment, the material of the positive active layer includes at least one of NaFePO4, NaMnPO4, NaCoPO4, Na4Fe3(PO4)2O7, Na3V2(PO4)2F3, Na3V2(PO4)3, Prussian blue, Prussian white, and modified versions of each of the above. For example, the material of the positive active layer includes at least one of NaFePO4, NaMnPO4, NaCoPO4, Na4Fe3(PO4)2O7, Na3V2(PO4)2F3, Na3V2(PO4)3, Prussian blue, and Prussian white. The above materials have a low oxygen release or do not release oxygen, and the oxygen release is not greater than 0.5% by mass.

[0199] In some embodiments, the material of the positive active layer can include at least one of NaFePO4, NaMnPO4, NaCoPO4, Na4Fe3(PO4)2O7, Na3V2(PO4)2F3, Na3V2(PO4)3, Prussian blue, Prussian white, and modified versions of each of the above. The modified versions can be doped or coated versions of the above materials. The above materials have stable properties and do not release oxygen or release a small amount of oxygen.

[0200] In an embodiment, the second battery cell 2 includes a housing, an electrode sheet assembly, and a first electrolyte. The electrode sheet assembly and the first electrolyte are both located in the housing.

[0201] The electrode sheet assembly is an energy storage structure of the second battery cell 2.

[0202] The electrode sheet assembly includes positive electrode sheets, negative electrode sheets, and separators. At least one separator is arranged between adjacent positive electrode sheets and negative electrode sheets. The separator is arranged between the positive electrode sheets and the negative electrode sheets, and can prevent short circuits.

[0203] The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is attached to at least one surface of the positive current collector in the thickness direction.

[0204] For example, the positive current collector has two opposite surfaces in the thickness direction thereof. Either one or both of the two opposite surfaces of the positive current collector in the thickness direction is / are provided with the positive active material layer. In an embodiment, one surface of the positive current collector in the thickness direction is provided with the positive active material layer. In another embodiment, both surfaces of the positive current collector in the thickness direction are provided with the positive active material layer.

[0205] The negative electrode sheet includes a negative current collector and a negative active material layer. The negative active material layer is attached to at least one surface of the negative current collector in the thickness direction.

[0206] Exemplarily, the negative current collector substrate has two surfaces opposite along a thickness direction of the negative current collector substrate, and the negative active material layer is arranged on any one or both of the two surfaces of the negative current collector substrate along the thickness direction. In an embodiment, the negative active material layer is arranged on one surface of the negative current collector substrate along the thickness direction. In another embodiment, the negative active material layer is arranged on both surfaces of the negative current collector substrate along the thickness direction.

[0207] In this embodiment, the first active ions in the first electrolyte migrate between the positive active material layer and the negative active material layer to realize charging and discharging. The separator can allow the first active ions to pass through.

[0208] In some embodiments, the second battery monomer 2 comprises one electrode sheet assembly. In other embodiments, the second battery monomer 2 comprises at least two electrode sheet assemblies, and the at least two electrode sheet assemblies can be stacked along the first direction.

[0209] In an embodiment, the positive electrode sheet is provided with a first positive electrode lug, and the negative electrode sheet is provided with a first negative electrode lug, and the first positive electrode lug and the first negative electrode lug can guide the current out of the electrode sheet assembly.

[0210] In some embodiments, the electrode sheet assembly is in a winding structure. Exemplarily, the positive electrode sheet, the negative electrode sheet and the separator are wound into a winding structure.

[0211] In some embodiments, the electrode sheet assembly is in a laminated structure.

[0212] Exemplarily, the positive electrode sheet, the negative electrode sheet and the separator are all at least two, the plurality of positive electrode sheets and the plurality of negative electrode sheets are alternately stacked, and one separator is arranged between adjacent positive electrode sheets and negative electrode sheets to form a laminated structure.

[0213] Exemplarily, the positive electrode sheet can be provided with a plurality of positive electrode sheets, and the negative electrode sheet is folded to form a plurality of folded segments arranged in layers, and one positive electrode sheet is clamped between adjacent folded segments to form a laminated structure.

[0214] Exemplarily, the positive electrode sheet and the negative electrode sheet are both folded to form a plurality of folded segments arranged in layers, and are alternately nested with each other to form a laminated structure.

[0215] In an embodiment, the first battery monomer 1 comprises a second electrolyte, and the second electrolyte is located in the shell 11. The positive electrode sheet comprises a positive current collector, and a positive active layer is attached to at least one surface of the positive current collector. The second active ions in the second electrolyte migrate between the positive active layer and the negative active layer to realize charging and discharging. The separator can allow the second active ions to pass through.

[0216] In an embodiment, the positive electrode sheet is provided with a second positive electrode lug, and the negative electrode sheet is provided with a second negative electrode lug, and the second positive electrode lug and the second negative electrode lug can guide the current out of the electrode assembly 12.

[0217] In some embodiments, the electrode assembly 12 is in a roll structure. For example, the positive electrode sheet, the negative electrode sheet and the separator are rolled to form the roll structure.

[0218] In some embodiments, the electrode assembly 12 is in a stack structure.

[0219] For example, the positive electrode sheet, the negative electrode sheet and the separator are all at least two, a plurality of positive electrode sheets and a plurality of negative electrode sheets are alternately stacked, and one separator is arranged between adjacent positive electrode sheets and negative electrode sheets to form the stack structure.

[0220] For example, the positive electrode sheet can be provided in a plurality, and the negative electrode sheet is folded to form a plurality of folded segments arranged in layers, and one positive electrode sheet is clamped between adjacent folded segments to form the stack structure.

[0221] For example, the positive electrode sheet and the negative electrode sheet are both folded to form a plurality of folded segments arranged in layers, and are alternately nested with each other to form the stack structure.

[0222] The shell is a hollow structure, and an accommodation cavity for accommodating the electrode sheet assembly and the first electrolyte is formed in the shell. The shell can be in various shapes, such as a cuboid and the like.

[0223] The shell 11 is a hollow structure, and an accommodation space for accommodating the electrode assembly 12 and the second electrolyte is formed in the shell 11. The shell 11 can be in various shapes, such as a cuboid and the like.

[0224] In some embodiments, the shell can be a hard structure. For example, the shell can be made of hard materials such as aluminum and / or steel.

[0225] In some embodiments, the shell includes a shell body and a cover. The shell body can be a hollow structure with one end open, and the cover closes the one end opening of the shell body. In this way, the cover and the shell body jointly define the accommodation cavity.

[0226] In some embodiments, the cover can be configured with a balance valve. The balance valve can pre-discharge part of the gas in the accommodation cavity, which is helpful for heat dissipation and avoiding accumulation of flammable gas at high temperature, and can improve the heat resistance temperature range.

[0227] In some embodiments, the shell 11 can be a hard structure. For example, the shell 11 can be made of hard materials such as aluminum and / or steel.

[0228] In some embodiments, the shell 11 includes a bottom shell and a top cover. The bottom shell can be a hollow structure with one end open, and the top cover closes the one end opening of the bottom shell. In this way, the top cover and the bottom shell jointly define the accommodation space.

[0229] In some embodiments, the top cover can be provided with a balance valve. The balance valve can pre-discharge part of the gas in the containing space, which is helpful for heat dissipation and avoiding accumulation of flammable gas at high temperature, and can improve the anti-heat temperature range.

[0230] The balance valve can include, but is not limited to, a breather valve or an explosion-proof valve, etc. The balance valve can be a one-way valve. The one-way valve of the cover body can limit the one-way outflow of the gas in the containing cavity to the outside. The one-way valve of the top cover can also limit the one-way outflow of the gas in the containing space to the outside.

[0231] In some embodiments, the positive current collecting substrate and the positive current collector can both be metal foils or composite current collectors. The metal foils can be made of aluminum, silver surface treated aluminum, or stainless steel, etc. The composite current collectors can include a polymer material base layer and a metal layer. The metal layer can be made of aluminum, aluminum alloy, or nickel, etc. The polymer material base layer can be made of polypropylene, polyethylene terephthalate, or polyethylene, etc.

[0232] It should be noted that the positive current collecting substrate and the positive current collector can be made of the same material or different materials.

[0233] In some embodiments, the negative current collecting substrate and the negative current collector 121 can both be metal foils or composite current collectors. The metal foils can be made of copper or nickel, etc. The composite current collectors can include a polymer material base material and a metal layer. The metal layer can be made of copper or nickel, etc. The polymer material base material can be made of polypropylene, polyethylene terephthalate, or polyethylene, etc.

[0234] It should be noted that the negative current collecting substrate and the negative current collector 121 can be made of the same material or different materials.

[0235] The first battery monomer 1 and the second battery monomer 2 can both be secondary batteries, which means that the active material can be activated by charging after discharging to continue to use.

[0236] For example, the first battery monomer 1 and the second battery monomer 2 in the battery 100 can be connected in series or in parallel or in a mixed connection, which means that the first battery monomer 1 and the second battery monomer 2 are connected in series and in parallel. The first battery monomer 1 and the second battery monomer 2 can be directly connected in series or in parallel or in a mixed connection; of course, the first battery monomer 1 and the second battery monomer 2 can be first connected in series or in parallel or in a mixed connection to form a battery 100 group, and then the battery 100 group is connected in series or in parallel or in a mixed connection to form a whole.

[0237] The battery 100 can also include other structures, for example, the battery 100 can also include a current collecting component for realizing the electrical connection between the first battery monomer 1 and the second battery monomer 2.

[0238] In some embodiments, the battery 100 includes one monomer unit 10.

[0239] In some embodiments, the battery 100 comprises at least two monomer units 10; the at least two monomer units 10 can be stacked along the third direction. Alternatively, the at least two monomer units 10 can be laid along the second direction. Alternatively, a plurality of monomer units 10 can be laid along the second direction to form a layer, and a plurality of layers of monomer units 10 can be stacked along the third direction.

[0240] In an exemplary embodiment, the material of the negative active layer of the first battery monomer 1 is sodium metal, and the separator film is PP or PE. The thermal runaway temperature of the second battery monomer 2 is not greater than 180℃, the second battery monomer 2 is a lithium ion battery 100, that is, the first active ion of the second battery monomer 2 is lithium ion. The second battery monomer 2 and the first battery monomer 1 are stacked along the first direction to form the monomer unit 10.

[0241] In this embodiment, on the one hand, the melting point of the negative active layer is lower than the thermal shrinkage temperature of the separator film. In the case of temperature rise in the shell 11, due to the relatively low melting point of the negative active layer, the temperature in the shell 11 will first reach the melting point of the negative active layer, so that the local melting of the negative active layer will occur first, the local melting of the negative active layer will separate from the negative plate to form a separator, the separator will separate from the negative plate, and the separator will not spread to the remaining negative active layer of the negative plate in a solid contact manner. That is, the local melting of the negative plate can inhibit the continuous thermal spread on the negative plate. The negative active layer will absorb heat during melting, which can delay or inhibit the continuous rise of the temperature in the shell 11, thereby breaking the continuous occurrence of internal thermal spread. The phase change of the local negative active layer can inhibit the temperature rise in the shell 11. In this way, the temperature in the shell 11 will be lower than the thermal shrinkage temperature of the separator film, that is, the separator film will not shrink, which can reduce the risk of short circuit between the positive plate and the negative plate, play a self-protection barrier role, inhibit thermal spread, and improve the safety performance of the first battery monomer 1. On the other hand, based on the lower single mass heat generation and the high gram capacity, the first battery monomer 1 with the same capacity has a lower heat generation capacity. The combination of the second battery monomer 2 and the first battery monomer 1 can provide the battery 100 with a wider mass energy density range and safety performance.

[0242] In the present disclosure, the thermal spread test can be performed in a manner known in the art, for example, the thermal spread test of the battery 100 can refer to the thermal diffusion test in Appendix C of GB 38031-2020. Exemplarily, the following test steps can be used:

[0243] S1: all test cells are fully charged (full charge refers to charging at 0.33C rate current to nominal voltage using constant current and constant voltage), arrange and electrically connect each cell into a module, use end plate and side plate to fix the module together or use steel belt to fix the module; select appropriate steel needle size (generally 3mm or 4mm in diameter) or heating plate (generally 500W, the power and size of the heating plate can be adjusted according to the capacity of the cell and the size of the shell);

[0244] S2: place the module in a simulated sealing box (the sealing box has an explosion-proof function), and monitor the voltage and temperature of each cell;

[0245] S3: heating plate verification of heat spread: select a first battery monomer 1 adjacent to a second battery monomer 2 in the module as a target cell, and place it close to the heating plate. The heating plate is plugged in for heating until the target cell fails (active failure), stop needle piercing, and observe the heat spread;

[0246] S4: after the target cell fails, stop heating and needle piercing (verification measure two options), continue to observe the module for two hours to confirm whether the other second battery monomers 2 and the other first battery monomers 1 on the non-trigger side in the module have heat spread (i.e. determine whether the cell fails); after cooling for 24 hours, perform appearance confirmation, capacity test on the second battery monomers 2 and the first battery monomers 1.

[0247] Among them, the heat spread determination standard: confirm whether there is a visible fire in other cells; if there is no visible fire, it means that there is no heat spread, and if there is a visible fire, it means that there is heat spread.

[0248] Among them, the cell failure standard: if any two of the following four conditions are met, the cell is considered to fail: ① temperature ≥ 280℃; ② cell temperature rise rate reaches: dT / dt ≥ 1℃ / s, and lasts for more than 3s; ③ cell voltage drop exceeds 25% of the initial voltage; ④ cell produces visible fire.

[0249] The above method can be used to determine whether the battery has heat spread and whether the cell has failed.

[0250] The following is a comparative example and two test examples of the present disclosure for heat spread test experiments:

[0251] Table 1

[0252] It should be noted that the ternary lithium battery monomer of the comparative example is a self-made cell, the positive active material uses lithium nickel manganese cobalt oxide, the negative active material uses graphite, the output voltage is 3.7V, and the capacity is 177Ah.

[0253] In the first test example of the present disclosure to the second test example of the present disclosure:

[0254] The first battery monomer is a self-made battery cell, the positive active layer uses Na4Fe3(PO4)2O7, the material of the negative active layer is shown in Table 1, the output voltage is 3.0 V, and the capacity is 130 Ah.

[0255] The second battery monomer is a self-made battery cell, the positive active material layer uses lithium nickel cobalt manganese oxide, the material of the negative active material layer uses graphite, the output voltage is 3.7 V, and the capacity is 177 Ah.

[0256] According to Table 1, the battery of the comparative example includes a module composed of five ternary lithium battery monomers stacked in the first direction in turn, the melting point of the negative active material layer of the ternary lithium battery monomer is higher than the heat shrinkage temperature of the isolation film, any one of the ternary lithium battery monomers between the two ends can be selected as a target battery cell, the heat spread test is performed on the comparative example, that is, the heat diffusion test is performed according to GB 38031-2020 Appendix C, the heat spread occurs in the comparative example, and the battery cell fails.

[0257] According to Table 1, in the first test example and the second test example of the present disclosure, the second battery monomer is a ternary lithium battery monomer, and the melting point of the negative active layer of the first battery monomer is lower than the heat shrinkage temperature of the isolation film; one of the first battery monomers adjacent to the second battery monomer 2 in the module is selected as a target battery cell, the heat spread test is performed on the first test example and the second test example of the present disclosure, that is, the heat diffusion test is performed according to GB 38031-2020 Appendix C, and the first test example and the second test example of the present disclosure do not occur heat spread, and the battery cell is effective. Therefore, the first battery monomer can play a self-protection barrier role, the first battery monomer can be used as a safety battery cell to isolate the second battery monomer and inhibit heat spread.

[0258] The above embodiments are only used to illustrate the technical solutions of the present disclosure, but not to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present disclosure, especially, as long as there is no structural conflict, each technical feature mentioned in the embodiments can be combined in any way.

Claims

A battery comprising: The first battery cell has a thermal runaway temperature of not less than 220°C. The second battery cell has a thermal runaway temperature of no more than 180°C; the first battery cell and the second battery cell are stacked along a first direction to form a component of a single cell unit. According to claim 1, wherein, The DSC heat generation of the negative electrode of the first battery cell is 300J / g to 1200J / g, and the DSC heat generation of the negative electrode of the second battery cell is 1500J / g to 3000J / g. According to claim 1, wherein, In any one of the said individual units, the ratio of the number of the second battery cells to the number of the first battery cells is 1:2 to 5:

1. According to claim 1, wherein, The second battery cell is a lithium-ion battery cell or a lithium metal battery cell. The battery according to claim 4, wherein, The second battery cell includes a positive electrode active material layer, the material of which includes at least one of nickel-cobalt-manganese ternary materials, lithium manganese oxide, lithium iron phosphate, and lithium manganese iron phosphate. The battery according to any one of claims 1 to 5, wherein, In the single-cell unit, the first battery cell and the second battery cell are alternately arranged along a first direction. The battery according to any one of claims 1 to 5, wherein, The single unit includes a heat insulation pad and at least two second battery cells, with at least one heat insulation pad disposed between two adjacent second battery cells. The battery according to any one of claims 1 to 7, wherein, The first battery cell includes: shell; An electrode assembly is located inside the housing. The electrode assembly includes a negative electrode, a positive electrode, and a separator. At least one separator is disposed between adjacent positive and negative electrode sheets. The negative electrode includes a negative current collector and a negative active layer. The negative active layer is disposed on at least one surface of the negative current collector along the thickness direction. The melting point of the negative active layer is lower than the heat shrinkage temperature of the separator. The battery according to claim 8, wherein, After the first battery cell is charged, the negative electrode active layer is deposited on at least one surface of the negative electrode current collector along the thickness direction. The battery according to claim 8, wherein, The material of the negative electrode active layer includes at least one of sodium metal and potassium metal. The battery according to claim 8, wherein, The surface of the negative electrode current collector is divided into at least two partition regions, and the negative electrode active layer is present in each partition region. The battery according to claim 11, wherein, The negative electrode sheet includes a support structure, and the support structure is disposed on at least one surface of the negative electrode current collector along the thickness direction, the support structure dividing the surface of the negative electrode current collector into at least two partition regions. The battery according to claim 12, wherein, The support structure is formed by printing or etching on the negative electrode current collector. The battery according to claim 12, wherein, The support structure includes at least two support bars, and at least a portion of the support bars form a closed area. The battery according to claim 12, wherein, The support structure includes a first support bar and a second support bar, which intersect. The battery according to claim 12, wherein, The negative electrode sheet includes a conductive layer, which is located between the negative electrode current collector and the supporting structure in the thickness direction of the negative electrode current collector. The battery according to claim 8, wherein, The first battery cell includes a flame-retardant component located within the housing, and the flame-retardant component is disposed on at least one surface of the separator along its thickness direction. The battery according to claim 17, wherein, The flame-retardant component includes a casing and a flame retardant, wherein the flame retardant is contained within the casing, and the melting point of the casing is lower than the heat shrinkage temperature of the insulating film. The battery according to claim 17, wherein, The flame-retardant component covers two surfaces of the insulating membrane along its thickness direction. The battery according to claim 8, wherein, The first battery cell includes an insulating heat insulation element located within the housing, and at least one of the electrode components is provided with the insulating heat insulation element on at least one side along the thickness direction, wherein the melting point of the insulating heat insulation element is lower than the heat shrinkage temperature of the separator. The battery according to claim 20, wherein, The insulating and heat-insulating component is made of at least one of paraffin wax, polyethylene, polymethyl methacrylate, polyethylene terephthalate, polytetrafluoroethylene, and melamine. The battery according to claim 8, wherein, The percentage of oxygen released by the positive electrode to the mass of the positive electrode active layer of the positive electrode is no more than 0.5 wt%. The battery according to claim 22, wherein, The positive electrode sheet includes a positive electrode active layer, and the material of the positive electrode active layer includes at least one of polyanionic, Prussian, and modified versions of each material. The battery according to claim 23, wherein, The positive electrode active layer is made of at least one of the following materials: NaFePO4, NaMnPO4, NaCoPO4, Na4Fe3(PO4)2O7, Na3V2(PO4)2F3, Na3V2(PO4)3, Prussian blue, Prussian white, and modifiers of each material. An electrical device comprising a battery as described in any one of claims 1 to 24 for providing electrical energy.

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