Low-temperature self-control self-heating all-solid-state battery

Abstract

The invention belongs to the technical field of solid-state batteries, and particularly relates to a low-temperature self-control self-heating all-solid-state battery which comprises a self-heating solid-state battery module and a normal solid-state battery module which are stacked and connected in series. A plurality of normal solid-state battery modules are stacked and connected in series with at least one self-heating solid-state battery module. The problems of low heating rate and non-uniform heating are solved through a built-in heating sheet mode, uniform and rapid heating is realized, the problem that the performance of a solid-state battery is greatly reduced in a low-temperature environment is further solved, the capacity retention ratio and the stability of the all-solid-state battery in the low-temperature environment are improved, and the use characteristics of the battery are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid-state batteries, and in particular relates to a low-temperature self-controlled self-heating all-solid-state battery. Background Art

[0002] Solid-state batteries are inherently safe due to the use of solid electrolyte materials. They are currently recognized as a potential mainstream power battery technology route in the future. Unlike traditional lithium-ion batteries with fluid electrolytes, solid-state batteries can stack multiple battery cells consisting of positive-electrolyte-negative electrodes in series, and use metal bipolar plates to replace the positive and negative current collectors of traditional liquid batteries (active materials of the same polarity on both sides), that is, the active materials on both sides of the bipolar plates have opposite polarities. Compared with the unipolar current collectors of traditional lithium-ion batteries, solid-state batteries using bipolar plates do not need to lead out and collect the current of each plate, so they have higher grouping efficiency.

[0003] However, compared with the liquid electrolyte of traditional lithium-ion batteries, the mass transfer capacity of solid electrolytes themselves and the kinetic performance of the electrode-electrolyte interface have decreased; especially in low temperature environments, the internal resistance of mass transfer and charge transfer will further increase, and the charge and discharge performance faces severe challenges; therefore, improving the low temperature performance of solid-state batteries is a key problem that needs to be solved urgently. The existing technologies mainly include the development of solid electrolytes and battery systems that adapt to low temperature conditions and heating batteries. Among them, the cycle of developing new material systems is long, and it is difficult to balance other aspects of performance, such as oxidation stability and compatibility with the positive and negative sides. The way to heat the battery can be divided into external and internal according to the heating position: external heating uses air or liquid convection in the heat dissipation cooling system to heat the battery, but is limited by the heat source and the heat generation and thermal conductivity of the material. This method has problems such as low heating rate (generally <1℃ / min) and uneven heating; internal heating uses built-in metal foil to reduce heat loss and heat transfer path, making the heating rate higher (up to 60℃ / min) and the battery cell more evenly heated, so it is a more promising heating solution.

[0004] However, the internal heating method has high requirements on the preparation and integration process of the heating plate, heating time and temperature control. At present, there are many public technologies related to heating control, most of which use temperature sensors to monitor the surface temperature of the battery, thereby realizing the on-off control of the heating circuit. However, the temperature sensor is usually arranged on the surface of the battery, and it is impossible to accurately obtain the temperature information inside the battery cell to achieve precise control. At the same time, the heating control circuit increases the complexity of the battery management system hardware and algorithm, and has a certain impact on the energy density of the battery system.

[0005] CN112786970A discloses an all-solid-state battery with self-heating function and a preparation method thereof. First, the electrolyte slurry is applied to the nickel mesh, and after drying, a composite electrolyte layer is obtained, and then the positive electrode sheet, the negative electrode sheet and the composite electrolyte layer stack are hot-pressed and packaged to form an all-solid-state battery. By using a metal nickel mesh to directly heat the solid electrolyte, the heat transfer path can be shortened and the battery core can be heated more evenly. However, the technical solution has high requirements for the control accuracy of the heating time and temperature, but the solution does not clearly define the control method for the on-off of the heating circuit; in addition, the nickel mesh in the solid electrolyte will hinder ion transport, resulting in uneven current distribution; at the same time, the nickel mesh also increases the risk of short circuit between the positive and negative electrodes.

[0006] CN112838296A discloses a low-temperature lithium battery intelligent heating device and method based on shape memory effect. This technology does not require additional heating devices and temperature relay switches, and can control the on and off of the self-heating circuit only through the shape memory heating sheet and the switch. However, the switch mode based on the shape memory metal sheet is a physical contact type, which requires a certain metal sheet travel space, thus affecting the energy density of the battery; in addition, at the moment when the switch contacts the heating sheet, due to the small and unstable contact area, it is very easy to cause electric sparks, thereby causing safety hazards inside the battery; and considering that the mechanical environment of the battery system in the actual automobile working conditions is very complex, it is easy to cause intermittent contact and heating between the memory switch and the surface of the battery pack, which not only causes electrode attenuation and energy loss, but also further exacerbates the safety risks. Summary of the invention

[0007] In view of the shortcomings of the existing methods, one of the purposes of the present invention is to provide an all-solid-state battery with self-heating function, which increases the heating rate, reduces energy consumption and improves the uniformity of heating of the battery cell by means of a built-in heating plate, thereby efficiently and stably improving the low-temperature performance of the solid-state battery.

[0008] In addition, precise control of heating time and temperature is also the key to effectively improving the low-temperature performance of the battery. Previously, most of the control strategies for battery self-heating were based on temperature sensors and control circuits. However, temperature sensors are usually difficult to implant inside the battery and obtain accurate temperature information; the on-off control of the circuit switch will increase the complexity of the electronic control and battery management algorithms. Therefore, the second purpose of the present invention is to use positive temperature coefficient (PTC) and negative temperature coefficient (NTC) materials based on a self-heating solid-state battery structure to construct a self-controlled heating component that automatically activates at low temperatures and automatically stops at normal temperatures, so as to achieve simple and efficient heating control.

[0009] The specific technical solution is:

[0010] The present invention provides a low-temperature self-controlled self-heating all-solid-state battery, which solves the problems of low heating rate and uneven heating by means of a built-in heating plate, achieves uniform and rapid heating, and further solves the problem of greatly reduced performance of solid-state batteries in low-temperature environments, improves the capacity retention rate and stability of all-solid-state batteries in low-temperature environments, and improves the battery's usage characteristics.

[0011] A low-temperature self-controlled self-heating all-solid-state battery, comprising a self-heating solid-state battery module and a normal solid-state battery module, wherein the self-heating solid-state battery module and the normal solid-state battery module are stacked and connected in series;

[0012] A plurality of normal solid-state battery modules are stacked in series and at least one self-heating solid-state battery module is connected.

[0013] A normal solid-state battery module includes a bipolar plate, a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer; the arrangement order of each layer includes:

[0014] Sequence A: bipolar plate-positive electrode active material-solid electrolyte-negative electrode active material;

[0015] Sequence B: bipolar plate-negative electrode active material-solid electrolyte-positive electrode active material;

[0016] Multiple normal solid-state battery modules stacked in series are in the same order.

[0017] The self-heating solid-state battery module includes a bipolar plate, a positive active material layer, a solid electrolyte layer, a negative active material layer, a PTC sheet, an NTC sheet, and a heating sheet. Bipolar plates are distributed on the upper and lower sides of the heating sheet, and the other side of the two bipolar plates and the positive active material layer, the solid electrolyte layer, and the negative active material layer respectively form a normal solid-state battery module, and the layers of the two normal solid-state battery modules are arranged in different orders. In the two normal solid-state battery modules, the active materials that are not in contact with the bipolar plates of the normal solid-state battery module are respectively in contact with the two bipolar plates in contact with the heating sheet, thereby forming a self-heating solid-state battery module. The outermost sides of the self-heating solid-state battery module are bipolar plates in two normal solid-state battery modules of different orders, which are stacked and connected in series with other multiple normal solid-state battery modules. When stacked and connected in series, the side of the bipolar plate close to the sequence A in the self-heating solid-state battery module is connected in series with the normal solid-state battery module of sequence A, and the side of the bipolar plate close to the sequence B in the self-heating solid-state battery module is connected in series with the normal solid-state battery module of sequence B.

[0018] There is a terminal at each end of the heating plate and at each end of the two bipolar plates in contact with the heating plate; the terminals on the same side of the two bipolar plates are connected through NTC sheets, the terminals on one side of the heating plate are in contact with the terminals on the same side of the bipolar plate in contact with its upper side through PTC sheets, and the terminals on the other side of the heating plate are in contact with the terminals on the same side of the bipolar plate in contact with its lower side through PTC sheets, forming a temperature control circuit and a heating circuit.

[0019] The bipolar plate material is Al, Cu, Ni, Ti or stainless steel SUS;

[0020] The material of the negative electrode active material layer is lithium, sodium, potassium, or an alloy composed of multiple metals among these metals.

[0021] The material of the solid electrolyte layer is one or more combinations of perovskite-type, NASICON-type, LISICON-type and garnet-type oxide solid electrolytes, or is selected from glassy Li2S-P2S5, crystalline Li x M y PS z , one or more of the sulfide solid electrolytes of glass-ceramic state Li2S-P2S5 and Li6PSX5, or one or more combinations selected from PEO, PPC, PCL, PTMC, SN, PAN, MEEP polymer solid electrolytes, or one or more combinations selected from Li3MX6 halide solid electrolytes;

[0022] Li x M y PS z Wherein M is one or more of Si, Ge, Sn, x+4y+5=2z, 0≤y≤1;

[0023] In Li6PSX5, X = Cl, Br, I;

[0024] In Li3MX6, M is a transition metal element, and X is a halogen element such as F, Cl, Br, or I.

[0025] The positive electrode active material layer is composed of positive electrode active material powder, conductive agent, binder, and solid electrolyte particles. The positive electrode active material powder includes lithium cobalt oxide LiCoO2, lithium manganese oxide LiMnO2, nickel cobalt manganese ternary lithium LiNi 1-x- y Co x Mn y O2, LiFePO4, LiMnFe 1-xPO4 and one or more of sulfur-containing positive electrode active materials; the conductive agent includes one or more combinations of carbon black conductive agent SP, graphite conductive agent and graphene conductive agent; the binder includes one or more combinations of polyvinylidene fluoride PVDF, polyacrylonitrile PAN, polymethyl methacrylate PMMA, styrene butadiene rubber SBR. Among them, nickel-cobalt-manganese ternary lithium LiNi 1-x-y Co x Mn y O2, where 0≤x≤0.5 and 0≤y≤0.5.

[0026] The heating sheet is composed of a surface insulating material and an internal metal sheet. The insulating material completely wraps the metal sheet, with only terminals extending on both sides. The internal metal sheet is composed of a single metal or alloy of Ni, Pt, Cu, Fe, Al;

[0027] The PTC sheet is prepared from a switch-type positive temperature coefficient conductive composite material, which is composed of a high molecular polymer and a conductive filler.

[0028] The NTC sheet is made of two or more of V2O5, MnO2, Co2O3 transition metal oxides or Al2O3 metal oxides by ceramic sintering process, or is prepared by V2O5 doped with Mo element by sol-gel method.

[0029] The all-solid-state battery with self-heating function provided by the present invention has the following advantages: it can solve the problems of low heating rate and uneven heating by means of built-in heating sheet; it has a simple structure and can be well combined with the production process of solid-state batteries; it is simple to prepare and can be prepared on a large scale; because the heating sheet is in full contact with the pole piece inside the battery, the contact area is large and the thermal conductivity is high, so efficient and uniform heating can be achieved when releasing heat. It solves the problem of greatly reduced performance of solid-state batteries in low temperature environments, improves the capacity retention rate and stability of all-solid-state batteries in low temperature environments, and improves the battery's use characteristics.

[0030] The self-controlled heating scheme based on self-heating all-solid-state batteries provided by the present invention has the following advantages: by adopting PTC and NTC materials, the self-controlled heating function of low-temperature heating and normal temperature stop is realized, and the algorithm complexity of the battery management and thermal management system is reduced; the number of electrical and mechanical components used is reduced, and the hardware complexity of the battery management and thermal management system is reduced; the scheme structure is simple and can be well combined with the production process of solid-state batteries; the PTC sheet and the NTC sheet are small in size and have high space utilization, thereby reducing the impact on the energy density of the battery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The low-temperature self-controlled self-heating all-solid-state battery structure of the present invention;

[0032] Figure 2 This is a schematic diagram of the connection mode of the low-temperature self-controlled self-heating structure of the present invention;

[0033] Figure 3 This is the equivalent circuit of the low-temperature self-controlled self-heating all-solid-state battery of the present invention. DETAILED DESCRIPTION

[0034] The present invention provides a low-temperature self-controlled self-heating all-solid-state battery, which solves the problems of low heating rate and uneven heating by means of a built-in heating plate 7, achieves uniform and rapid heating, and further solves the problem of greatly reduced performance of solid-state batteries in low-temperature environments, improves the capacity retention rate and stability of all-solid-state batteries in low-temperature environments, and improves the battery's use characteristics.

[0035] like Figure 1 As shown, a low-temperature self-controlled self-heating all-solid-state battery is composed of self-heating solid-state battery modules and normal solid-state battery modules stacked in series. The number of modules can be selected according to demand, and the arrangement of modules is not limited. It can be that one self-heating solid-state battery module is stacked in series for every two normal solid-state battery modules, or at least one self-heating solid-state battery module is stacked in series for every three normal solid-state battery modules.

[0036] A normal solid-state battery module is composed of a bipolar plate 1, a positive electrode active material layer 2, a solid electrolyte layer 3, and a negative electrode active material layer 4. The arrangement order of each layer can be sequence A: bipolar plate 1-positive electrode active material-solid electrolyte-negative electrode active material (if the effect of negative electrode active material-solid electrolyte-positive electrode active material-bipolar plate 1 is the same as this order after reversing, it is considered to be the same order), otherwise it is sequence B: bipolar plate 1-negative electrode active material-solid electrolyte-positive electrode active material (if the effect of positive electrode active material-solid electrolyte-negative electrode active material-bipolar plate 1 is the same as this order after reversing, it is considered to be the same order). When multiple normal solid-state battery modules are stacked in series, active materials of different polarities need to be distributed on the upper and lower sides of the bipolar plate 1, that is, the polarity of the active material that is not in contact with the bipolar plate 1 in the previous normal solid-state battery module is opposite to the polarity of the active material in contact with the bipolar plate 1 in the next normal solid-state battery module, that is, the multiple normal solid-state battery modules stacked in series are in the same order.

[0037] The self-heating solid-state battery module is composed of a bipolar plate 1, a positive electrode active material layer 2, a solid electrolyte layer 3, a negative electrode active material layer 4, a PTC sheet 5, an NTC sheet 6, and a heating sheet 7. Bipolar plates 1 are distributed on the upper and lower sides of the heating sheet 7. The other sides of the two bipolar plates 1 in contact with the heating sheet 7 respectively form the normal solid-state battery module described above with the positive electrode active material layer 2, the solid electrolyte layer 3, and the negative electrode active material layer 4, and the two normal solid-state battery modules are in different orders. The active materials in the two normal solid-state battery modules that are not in contact with the bipolar plates 1 of their own modules are respectively in contact with the two bipolar plates 1 in contact with the heating sheet 7, thereby forming a self-heating solid-state battery module. The outermost sides of the self-heating solid-state battery module are bipolar plates 1 in two normal solid-state battery modules of different orders, which can be stacked and connected in series with other multiple normal solid-state battery modules. When stacked and connected in series, the side of the bipolar plate 1 close to the sequence A in the self-heating solid-state battery module can only be connected in series with the normal solid-state battery module of sequence A, and the side of the bipolar plate 1 close to the sequence B in the self-heating solid-state battery module can only be connected in series with the normal solid-state battery module of sequence B. In this way, by connecting multiple normal solid-state battery modules in series, and connecting normal solid-state battery modules in series with self-heating solid-state battery modules, a full solid-state battery with self-heating function is finally formed.

[0038] The low-temperature self-controlled self-heating all-solid-state battery of the present invention also includes a self-heating solid-state battery that automatically adjusts the heating circuit on and off according to the internal temperature of the battery without human or circuit control. Figure 1 As shown, in the self-heating solid-state battery module, there is a terminal at both ends of the heating plate 7 and at both ends of the two bipolar plates 1 in contact with the heating plate 7, which are used to form a circuit connection with other components. The terminals on the same side of the two bipolar plates 1 are connected through the NTC sheet 6, and the terminal on one side of the heating plate 7 is in contact with the right terminal of the bipolar plate 1 in contact with its upper side through the PTC sheet 5. The terminal on the other side of the heating plate 7 is in contact with the left terminal of the bipolar plate 1 in contact with its lower side through the PTC sheet 5, thereby forming a temperature control circuit and a heating circuit. The above connection method is not limited to welding, bonding, or sputtering, coating, sintering, sol-gel method and other methods on a unified current collector to prepare the above NTC and PTC materials. Figure 2 A schematic diagram of one of the bonding connection methods.

[0039] To understand its working principle, the equivalent circuit is as follows: Figure 3 As shown. The heating plate 7 in the self-heating solid-state battery module is equivalent to Figure 3The resistance element in the figure, the two bipolar plates 1 in contact with the heating plate 7 are equivalent to the wires in the circuit, and the PTC sheet 5 and the NTC sheet 6 are equivalent to the switches in the figure. The PTC sheet 5 has the following characteristics: when the current is connected, as the internal temperature of the battery rises, the resistivity of the PTC sheet 5 rises rapidly within a specific temperature or a specific temperature range, so that the resistance of the PTC sheet 5 approaches infinity, and the current passing through approaches infinitesimal, thereby playing the role of a switch disconnection. The NTC sheet 6 has the following characteristics: when the current is connected, due to the high initial resistivity, the resistance of the NTC sheet 6 approaches infinity, and the current passing through approaches infinitesimal, and it is in an open circuit state. As the internal temperature of the battery rises, the resistivity of the NTC sheet 6 drops rapidly within a specific temperature or a specific temperature range, so that the resistance of the NTC sheet 6 decreases, and the current passing through increases, thereby playing the role of connecting the circuit.

[0040] Specifically in practical applications, the resistivity of the PTC sheet 5 is relatively low at 0°C and below, and the resistivity increases rapidly with the increase of temperature in the range of 0°C to 20°C. The above characteristics make the PTC sheet 5 have a relatively low resistance at low temperatures, and the resistance value at room temperature approaches infinity. The resistivity of the NTC sheet 6 is relatively high at 0°C and below, and the resistivity decreases rapidly with the increase of temperature in the range of 0°C to 20°C. The above characteristics make the PTC sheet 5 have an extremely high resistance at low temperatures, and a relatively low resistance value at room temperature. When the low-temperature self-controlled self-heating all-solid-state battery is in a sub-zero environment, according to the above characteristics, the PTC sheet 5 has a low resistance value, and forms a heating path after being connected with the heating sheet 7, while the resistance value of the NTC sheet 6 tends to infinity at low temperatures, and the path current formed after being connected with the bipolar plate 1 is very small, which is equivalent to an open circuit. Therefore, in the built-in self-heating solid-state battery module inside the low-temperature self-controlled self-heating all-solid-state battery, the current flows in the direction of bipolar plate 1-PTC sheet 5-heating sheet 7-PTC sheet 5-bipolar plate 1, and the current generates Joule heat after passing through the heating sheet 7, which affects the positive pole inside the battery. The negative electrode sheet and the solid electrolyte are heated; as the heat accumulates, when the internal temperature of the battery rises to 20°C, according to the temperature characteristics of the PTC sheet 5 and the NTC sheet 6, the resistance of the PTC sheet 5 increases rapidly and tends to infinity, and the circuit between the bipolar plate 1 connected to it and the heating sheet 7 is disconnected, the heating sheet 7 no longer generates Joule heat, the resistance of the NTC sheet 6 decreases, and the two bipolar plates 1 connected to it are turned on to form a path, and the current flows from the bipolar plate 1-NTC sheet 6-bipolar plate 1. At this time, the battery can work normally and has good performance.

[0041] In order to achieve the above-mentioned purpose of the invention, the present invention adopts the following technical solutions:

[0042] Low-temperature self-controlled self-heating all-solid-state battery, including normal solid-state battery module and self-heating solid-state battery module.

[0043] (1) Normal solid-state battery module

[0044] A normal solid-state battery module is composed of a negative electrode active material layer 4 , a solid electrolyte layer 3 , a positive electrode active material layer 2 , and a bipolar plate 1 .

[0045] The material of the negative electrode active material layer 4 includes, but is not limited to, metals such as lithium, sodium, potassium, or alloys composed of multiple metals among these metals.

[0046] The material of the solid electrolyte layer 3 is a perovskite type (such as Li 0.33 La 0.56 TiO3, LLTO), NASICON type (such as Li 1.3 Al 0.3 Ti 1.7 (PO4)3, LATP), LISICON (such as Li 10 GeP2S 12 , LGPS) type and garnet type (such as Li7La3Zr2O 12 ,LLZO) oxide solid electrolyte, or selected from glassy Li2S-P2S5, crystalline Li x M y PS z (wherein M is one or more of Si, Ge, Sn, x+4y+5=2z, 0≤y≤1), one or more combinations of sulfide solid electrolytes such as glass-ceramic Li2S-P2S5 and Li6PSX5 (X=Cl, Br, I), or one or more combinations selected from PEO, PPC, PCL, PTMC, SN, PAN, MEEP polymer solid electrolytes, or one or more combinations selected from Li3MX6 (M is a transition metal element, X=F, Cl, Br, I halogen element) and other halide solid electrolytes.

[0047] The positive electrode active material layer 2 is composed of positive electrode active material powder, conductive agent, binder, and solid electrolyte particles. The positive electrode active material powder includes lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMnO2), nickel cobalt manganese ternary lithium (LiNi 1-x- y Co x Mn y O2, where 0≤x≤0.5 and 0≤y≤0.5), lithium iron phosphate (LiFePO4), lithium manganese iron phosphate (LiMnFe 1-x PO4) and one or more of sulfur-containing positive electrode active materials; the conductive agent includes one or more combinations of carbon black conductive agent (SP), graphite conductive agent and graphene conductive agent; the binder includes one or more combinations of polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and styrene-butadiene rubber (SBR).

[0048] The bipolar plate 1 can be made of metal foil such as Al, Cu, Ni, Ti, or stainless steel SUS.

[0049] (2) Self-heating solid-state battery module

[0050] The self-heating solid-state battery module consists of a bipolar plate 1, a positive electrode active material layer 2, a solid electrolyte layer 3, a negative electrode active material layer 4, a PTC sheet 5, an NTC sheet 6, and a heating sheet 7.

[0051] The material of the negative electrode active material layer 4 includes, but is not limited to, metals such as lithium, sodium, potassium, or alloys composed of multiple metals among these metals.

[0052] The material of the solid electrolyte layer 3 is a perovskite type (such as Li 0.33 La 0.56 TiO3, LLTO), NASICON type (such as Li 1.3 Al 0.3 Ti 1.7 (PO4)3, LATP), LISICON (such as Li 10 GeP2S 12 , LGPS) type and garnet type (such as Li7La3Zr2O 12 ,LLZO) oxide solid electrolyte, or selected from glassy Li2S-P2S5, crystalline Li x M y PS z (wherein M is one or more of Si, Ge, Sn, x+4y+5=2z, 0≤y≤1), one or more combinations of sulfide solid electrolytes such as glass-ceramic Li2S-P2S5 and Li6PSX5 (X=Cl, Br, I), or one or more combinations selected from PEO, PPC, PCL, PTMC, SN, PAN, MEEP polymer solid electrolytes, or one or more combinations selected from Li3MX6 (M is a transition metal element, X=F, Cl, Br, I halogen element) and other halide solid electrolytes.

[0053] The positive electrode active material layer 2 is composed of positive electrode active material powder, conductive agent, binder, and solid electrolyte particles. The positive electrode active material powder includes lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMnO2), nickel cobalt manganese ternary lithium (LiNi 1-x- y Co x Mn y O2, where 0≤x≤0.5 and 0≤y≤0.5), lithium iron phosphate (LiFePO4), lithium manganese iron phosphate (LiMnFe 1-xPO4), and one or more of sulfur-containing positive electrode active materials; the conductive agent includes one or more combinations of carbon black conductive agent (SP), graphite conductive agent and graphene conductive agent; the binder includes one or more combinations of polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and styrene-butadiene rubber (SBR).

[0054] The bipolar plate 1 can be made of metal foil such as Al, Cu, Ni, Ti, or stainless steel SUS.

[0055] The heating sheet 7 is composed of a surface insulating material and an internal metal sheet. The insulating material completely wraps the metal sheet, with only terminals extending on both sides. The insulating material can be an organic insulating polymer such as polyimide (PI), polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), etc. The internal metal sheet is composed of a single metal or alloy such as Ni, Pt, Cu, Fe, or Al.

[0056] The PTC sheet 5 is made of a switch-type positive temperature coefficient conductive composite material, which is generally composed of a high molecular polymer and a conductive filler. The high molecular polymer is made of polyolefins such as polyethylene, polyethylene oxide (PEO), polyvinyl chloride (PVC), and ethylene-vinyl acetate copolymer (EVA); the conductive filler is made of conductive carbon black, graphite, graphene, and highly conductive metals such as nickel powder, copper powder, aluminum powder, and platinum powder.

[0057] The NTC sheet 6 is made of two or more transition metal oxides such as V2O5, MnO2, Co2O3 or metal oxides such as Al2O3 by a ceramic sintering process, or prepared by magnetron sputtering, or prepared by V2O5 doped with Mo element by a sol-gel method.

[0058] The connection method of the NTC sheet 6 and the PTC sheet 5 to the bipolar plate 1 and the two ends of the heating sheet 7 terminal is not limited to ultrasonic welding, laser welding, friction welding and other welding methods, or conductive gel bonding, and is not limited to organic polymers or organic-inorganic composite materials with electronic conductivity.

[0059] Example 1: Low-temperature self-controlled self-heating all-solid-state battery

[0060] like Figure 1 and Figure 2As shown, the all-solid-state battery with self-heating function is composed of self-heating solid-state battery modules and normal solid-state battery modules stacked in series. The number of modules can be selected according to demand, and the arrangement of modules is not limited. It can be that at least one self-heating solid-state battery module is stacked in series for every two normal solid-state battery modules, or at least one self-heating solid-state battery module is stacked in series for every three normal solid-state battery modules.

[0061] (1) Normal solid-state battery module

[0062] A normal solid-state battery module is composed of a bipolar plate 1, a positive electrode active material layer 2, a solid electrolyte layer 3, and a negative electrode active material layer 4. The materials are selected as follows:

[0063] 1) The bipolar plate 1 is 20 μm SUS 316L stainless steel;

[0064] 2) The positive electrode active material layer 2 has a thickness of 200 μm and is composed of 95% by mass of positive electrode active material NMC622, 1% of polyvinylidene fluoride (PVDF), 2% of carbon black conductive agent (SP), and 2% of solid electrolyte particles, wherein NMC622 is a nickel-manganese-cobalt ternary material, and LiNi 1-x-y Co x Mn y O2 (where 0≤x≤0.5, 0≤y≤0.5), when x=0.2y=0.2 is NMC622, the material of the solid electrolyte particles is lithium lanthanum zirconium oxide LLZO (Li7La3Zr2O 12 );

[0065] 3) The solid electrolyte layer 3 is lithium lanthanum zirconium oxide LLZO (Li7La3Zr2O 12 ) garnet-type oxide solid electrolyte;

[0066] 4) The negative electrode active material layer 4 is made of metallic lithium with a thickness of 300 μm.

[0067] The arrangement order of each layer can be sequence A: bipolar plate 1-positive electrode active material-solid electrolyte-negative electrode active material (if the effect of negative electrode active material-solid electrolyte-positive electrode active material-bipolar plate 1 is the same as this order after reversing, it is considered to be the same order), otherwise it is sequence B: bipolar plate 1-negative electrode active material-solid electrolyte-positive electrode active material (if the effect of positive electrode active material-solid electrolyte-negative electrode active material-bipolar plate 1 is the same as this order after reversing, it is considered to be the same order). When multiple normal solid-state battery modules are stacked in series, active materials of different polarities need to be distributed on the upper and lower sides of the bipolar plate 1, that is, the polarity of the active material that is not in contact with the bipolar plate 1 in the previous normal solid-state battery module is opposite to the polarity of the active material in contact with the bipolar plate 1 in the next normal solid-state battery module, that is, the multiple normal solid-state battery modules stacked in series are in the same order. In this embodiment, 3 modules of sequence A and sequence B are prepared respectively. Take two modules of sequence A and compact them for stacking and connecting them in series, and take two modules of sequence B and compact them for stacking and connecting them in series to obtain a normal solid-state battery module after stacking and connecting them in series.

[0068] (2) Self-heating solid-state battery module

[0069] The self-heating solid-state battery module is composed of a bipolar plate 1, a positive electrode active material layer 2, a solid electrolyte layer 3, a negative electrode active material layer 4, a PTC sheet 5, an NTC sheet 6, and a heating sheet 7. The material selection and preparation process are as follows:

[0070] 1) The bipolar plate 1 is 20 μm SUS 316L stainless steel;

[0071] 2) The heating plate 7 is composed of a surface insulating material and an internal metal sheet. The surface insulating material is polyethylene (PE), and the internal metal sheet is a metal nickel sheet. There are protruding terminals at both ends of the nickel sheet. The insulating material polyethylene completely wraps the metal nickel sheet.

[0072] 3) The PTC sheet 5 is made of a switch-type positive temperature coefficient conductive composite material, which is generally composed of a high molecular polymer and a conductive filler. The high molecular polymer is polyethylene, and the conductive filler is nickel powder, which is sintered to form a sheet-like conductive material;

[0073] 4) The NTC sheet 6 is prepared by V2O5 doped with Mo element through a sol-gel method;

[0074] 5) The contact between NTC, PTC and bipolar plate 1 is achieved by ultrasonic welding.

[0075] There is a terminal at both ends of the heating plate 7 and at both ends of the two bipolar plates 1 in contact with the heating plate 7, which are used to form a circuit connection with other components. The terminals on the same side of the two bipolar plates 1 are connected through the NTC plate 6, and the terminal on one side of the heating plate 7 is in contact with the right terminal of the bipolar plate 1 in contact with its upper side through the PTC plate 5, and the terminal on the other side of the heating plate 7 is in contact with the left terminal of the bipolar plate 1 in contact with its lower side through the PTC plate 5, thereby forming a temperature control circuit and a heating circuit.

[0076] Bipolar plates 1 are distributed on the upper and lower sides of the heating plate 7. Two normal solid-state battery modules as described above are distributed on the other side of each of the two bipolar plates 1 in contact with the heating plate 7, and the two normal solid-state battery modules are in different orders. The active materials in the two normal solid-state battery modules that are not in contact with the bipolar plates 1 of the module are in contact with the other side of the two bipolar plates 1 in contact with the heating plate 7, respectively, so as to form a self-heating solid-state battery module. In this embodiment, one normal solid-state battery module of sequence A and sequence B remaining prepared in step (1) is taken, and the sequence A normal solid-state battery module is placed above the bipolar plate 1 in contact with the upper side of the heating plate 7, so that the negative electrode active material layer 4 in the sequence A normal solid-state battery module is close to the bipolar plate 1; the sequence B normal solid-state battery module is placed below the bipolar plate 1 in contact with the lower side of the heating plate 7, so that the positive electrode active material layer 2 in the sequence B normal solid-state battery module is close to the bipolar plate 1, and a self-heating solid-state battery module is formed after compaction. The outermost sides of the self-heating solid-state battery module are bipolar plates 1 in two normal solid-state battery modules of different orders, which can be stacked and connected in series with multiple other normal solid-state battery modules. When stacked and connected in series, the side of the bipolar plate 1 close to the sequence A in the self-heating solid-state battery module can only be connected in series with the normal solid-state battery module of sequence A, and the side of the bipolar plate 1 close to the sequence B in the self-heating solid-state battery module can only be connected in series with the normal solid-state battery module of sequence B. In this way, by connecting multiple normal solid-state battery modules in series, and connecting normal solid-state battery modules and self-heating solid-state battery modules in series, a full solid-state battery with a self-heating function is finally formed. In this embodiment, the two sequential A modules stacked in series and the two sequential B modules stacked in series prepared in advance in step (1) are taken, and the two sequential A modules stacked in series are placed above the self-heating solid-state battery module to ensure that the top bipolar plate 1 of the self-heating solid-state battery module is in contact with the exposed negative electrode active material layer 4 of the two sequential A modules; the two sequential B modules stacked in series are placed below the self-heating solid-state battery module to ensure that the bottom bipolar plate 1 of the self-heating solid-state battery module is in contact with the exposed positive electrode active material layer 2 of the two sequential B modules. After lamination and compaction, the series connection of the normal solid-state battery module and the self-heating solid-state battery module is completed, and finally an all-solid-state battery with self-heating function is formed.

[0077] Example 2: Application of low-temperature self-controlled self-heating all-solid-state battery

[0078] The low-temperature self-controlled self-heating all-solid-state battery prepared in Example 1 was placed in a battery environmental test box, the ambient temperature was set to -20°C, and a 0.2C low-rate charge and discharge experiment was performed on it. Its equivalent circuit is as follows Figure 3 As shown. The normal solid-state battery module is equivalent to the power supply in the circuit, and the heating plate 7 in the self-heating solid-state battery module is equivalent to Figure 2 The resistance element in the figure, the two bipolar plates 1 in contact with the heating plate 7 are equivalent to the wires in the circuit, and the PTC sheet 5 and the NTC sheet 6 are equivalent to the switches in the figure. The PTC sheet 5 has the following characteristics: when the current is connected, as the internal temperature of the battery rises, the resistivity of the PTC sheet 5 rises rapidly within a specific temperature or a specific temperature range, so that the resistance of the PTC sheet 5 approaches infinity, and the current passing through approaches infinitesimal, thereby playing the role of a switch disconnection. The NTC sheet 6 has the following characteristics: when the current is connected, due to the high initial resistivity, the resistance of the NTC sheet 6 approaches infinity, and the current passing through approaches infinitesimal, and it is in an open circuit state. As the internal temperature of the battery rises, the resistivity of the NTC sheet 6 drops rapidly within a specific temperature or a specific temperature range, so that the resistance of the NTC sheet 6 decreases, and the current passing through increases, thereby playing the role of connecting the circuit. In this embodiment, the resistivity of the PTC sheet 5 is relatively low at -20°C, and acts as a conductive wire connection, which is equivalent to a closed switch. The resistivity of the NTC sheet 6 is relatively high at -20°C, and acts as a circuit breaker, which is equivalent to a disconnected switch. Thus, in the solid-state battery module with a built-in heating sheet 7 inside the self-controlled self-heating all-solid-state battery, the current flows in the direction of bipolar plate 1-PTC sheet 5-heating sheet 7-PTC sheet 5-bipolar plate 1. After the current passes through the heating sheet 7, Joule heat is quickly generated, which quickly and evenly heats the positive and negative electrodes and the solid electrolyte inside the battery. Uniform heating; as the heat accumulates, when the internal temperature of the battery rises to about 20°C, since the resistivity of the PTC sheet 5 in the range of 0°C to 20°C increases rapidly with the increase of temperature, the resistance value approaches infinity, and the current passes through it approaches 0, which is equivalent to the switch being disconnected. The resistivity of the NTC sheet 6 in the range of 0°C to 20°C decreases rapidly with the increase of temperature, and the resistance value decreases rapidly. The two bipolar plates 1 connected to it are turned on, which is equivalent to the switch being closed, forming a path, and the current flows from bipolar plate 1-NTC sheet 6-bipolar plate 1. At this time, the battery can work normally and has good performance.

Claims

1. A low-temperature self-controlled self-heating all-solid-state battery, characterized in that: It comprises a self-heating solid-state battery module and a normal solid-state battery module, wherein the self-heating solid-state battery module and the normal solid-state battery module are stacked in series; A plurality of normal solid-state battery modules are stacked in series and at least one self-heating solid-state battery module is connected.

2. A low-temperature self-controlled self-heating all-solid-state battery according to claim 1, characterized in that: The normal solid-state battery module comprises a bipolar plate (1), a positive electrode active material layer (2), a solid electrolyte layer (3), and a negative electrode active material layer (4); the arrangement order of each layer includes: Sequence A: bipolar plate-positive electrode active material-solid electrolyte-negative electrode active material; Sequence B: bipolar plate-negative electrode active material-solid electrolyte-positive electrode active material; Multiple normal solid-state battery modules stacked in series are in the same order.

3. A low-temperature self-controlled self-heating all-solid-state battery according to claim 2, characterized in that: The self-heating solid-state battery module comprises a bipolar plate (1), a positive electrode active material layer (2), a solid electrolyte layer (3), a negative electrode active material layer (4), a PTC sheet (5), an NTC sheet (6), and a heating sheet (7); the bipolar plates (1) are distributed on the upper and lower sides of the heating sheet (7); the other sides of the two bipolar plates (1) and the positive electrode active material layer (2), the solid electrolyte layer (3), and the negative electrode active material layer (4) respectively form a normal solid-state battery module, and the arrangement order of the layers of the two normal solid-state battery modules is different; The two ends of the heating plate (7) and the two ends of the two bipolar plates (1) in contact with the heating plate (7) each have a terminal; the terminals on the same side of the two bipolar plates (1) are connected via NTC plates (6), the terminal on one side of the heating plate (7) is in contact with the terminal on the same side of the bipolar plate (1) in contact with its upper side via a PTC plate (5), and the terminal on the other side of the heating plate (7) is in contact with the terminal on the same side of the bipolar plate (1) in contact with its lower side via a PTC plate (5), thereby forming a temperature control circuit and a heating circuit.

4. A low-temperature self-controlled self-heating all-solid-state battery according to claim 2, characterized in that: The bipolar plate (1) is made of Al, Cu, Ni, Ti or stainless steel (SUS).

5. A low-temperature self-controlled self-heating all-solid-state battery according to claim 2, characterized in that: The material of the negative electrode active material layer (4) is lithium, sodium, potassium, or an alloy composed of multiple metals among these metals.

6. A low-temperature self-controlled self-heating all-solid-state battery according to claim 2, characterized in that: The material of the solid electrolyte layer (3) is one or more combinations of perovskite-type, NASICON-type, LISICON-type and garnet-type oxide solid electrolytes, or is selected from glassy Li2S-P2S5, crystalline Li x M y PS z , one or more of the sulfide solid electrolytes of glass-ceramic state Li2S-P2S5 and Li6PSX5, or one or more combinations selected from PEO, PPC, PCL, PTMC, SN, PAN, MEEP polymer solid electrolytes, or one or more combinations selected from Li3MX6 halide solid electrolytes; Li x M y PS z Wherein M is one or more of Si, Ge, Sn, x+4y+5=2z, 0≤y≤1; In Li6PSX5, X=Cl, Br, I; In Li3MX6, M is a transition metal element, and X is a halogen element such as F, Cl, Br, or I.

7. A low-temperature self-controlled self-heating all-solid-state battery according to claim 2, characterized in that: The positive electrode active material layer (2) is composed of positive electrode active material powder, conductive agent, binder, and solid electrolyte particles; wherein the positive electrode active material powder includes lithium cobalt oxide LiCoO2, lithium manganese oxide LiMnO2, nickel cobalt manganese ternary lithium LiNi 1-x-y Co x Mn y O2, LiFePO4, LiMnFe 1-x PO4 and one or more of sulfur-containing positive electrode active materials; the conductive agent includes one or more combinations of carbon black conductive agent SP, graphite conductive agent and graphene conductive agent; the binder includes one or more combinations of polyvinylidene fluoride PVDF, polyacrylonitrile PAN, polymethyl methacrylate PMMA, styrene-butadiene rubber SBR; Among them, nickel-cobalt-manganese ternary lithium LiNi 1-x-y Co x Mn y O2, where 0≤x≤0.5 and 0≤y≤0.

5.

8. A low-temperature self-controlled self-heating all-solid-state battery according to claim 2, characterized in that: The heating plate (7) is composed of a surface insulating material and an internal metal sheet. The insulating material completely wraps the metal sheet, with only terminals extending out on two sides. The internal metal sheet is composed of a single metal or an alloy of Ni, Pt, Cu, Fe, Al.

9. A low-temperature self-controlled self-heating all-solid-state battery according to claim 2, characterized in that: The PTC sheet (5) is prepared from a switch-type positive temperature coefficient conductive composite material, which is composed of a high molecular polymer and a conductive filler.

10. A low-temperature self-controlled self-heating all-solid-state battery according to claim 2, characterized in that: The NTC sheet (6) is made of two or more of V2O5, MnO2, Co2O3 transition metal oxides or Al2O3 metal oxides by using a ceramic sintering process, or is prepared by doping V2O5 with Mo elements by a sol-gel method.

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