WO2024077591A1 - 内串联电池及用电装置 - Google Patents

内串联电池及用电装置 Download PDF

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WO2024077591A1
WO2024077591A1 PCT/CN2022/125328 CN2022125328W WO2024077591A1 WO 2024077591 A1 WO2024077591 A1 WO 2024077591A1 CN 2022125328 W CN2022125328 W CN 2022125328W WO 2024077591 A1 WO2024077591 A1 WO 2024077591A1
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battery
electrode active
active material
battery cell
positive electrode
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PCT/CN2022/125328
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English (en)
French (fr)
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宋佩东
吴李力
孙信
云亮
李璇
董苗苗
陈兴布
刘润蝶
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/125328 priority Critical patent/WO2024077591A1/zh
Publication of WO2024077591A1 publication Critical patent/WO2024077591A1/zh

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries

Definitions

  • the present application relates to the field of secondary batteries, and in particular to an internally-connected series battery and an electrical device.
  • the present application provides an internal series battery and an electrical device having both higher energy density and better safety performance.
  • an inner series battery comprising:
  • a series module comprising battery cells and an intermediate current collector; the number of the battery cells is ⁇ 3, each of the battery cells comprises a positive electrode active material layer, a solid electrolyte layer and a negative electrode active material layer arranged in a stacked manner; the intermediate current collector is arranged between two adjacent battery cells, and the two adjacent battery cells are connected in series via the intermediate current collector;
  • a positive electrode current collector located at one end of the series module and electrically connected to the positive electrode active material layer of the battery cell at the end;
  • a negative electrode current collector located at the other end of the series module and electrically connected to the negative electrode active material layer of the battery cell at the end;
  • the battery cell includes a first battery cell and a second battery cell; the energy density of the first battery cell is the same as the energy density of any battery cell located at both ends of the series module; the energy density of the second battery cell is different from the energy density of the battery cells located at both ends of the series module.
  • the battery cells are connected in series via an intermediate current collector.
  • the internal series battery has both high energy density and good safety performance.
  • the ratio of the number of the second battery cells to the total number of the battery cells is (1-2): 3.
  • the number of the second battery cells is within the above range, the energy density and safety performance of the inner series battery can be reasonably adjusted, and the overall performance of the inner series battery is better.
  • the energy density of the first battery cell is greater than the energy density of the second battery cell.
  • a battery system with a larger energy density has relatively poor thermal stability and a greater risk of thermal failure.
  • the energy density of the first battery cell is greater than the energy density of the second battery cell, which is beneficial to the theoretical energy density of the inner series battery.
  • the inner series battery has a higher energy density, better kinetic performance and better thermal stability.
  • the energy density of the negative electrode active material of the first battery cell is greater than the energy density of the negative electrode active material of the second battery cell; negative electrode active materials with greater energy density generally have average thermal stability, while negative electrode active materials with average energy density generally have better thermal stability.
  • the negative electrode active material of each of the first battery cells independently includes at least one of a silicon-based material, a tin-based material and lithium metal; the above-mentioned negative electrode active material has a high theoretical energy density, but the thermal stability of the material is general.
  • the first battery cell adopts the above-mentioned negative electrode active material, and the battery cells at both ends of the series module have a high energy density.
  • the internal series batteries can improve the energy density while taking into account thermal stability.
  • the negative electrode active material of each of the second battery cells independently includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon and lithium titanate.
  • the theoretical energy density of the above negative electrode active materials is average, but they have good thermal stability.
  • the use of the above negative electrode active materials in the second battery cells can ensure that the battery cells inside the series module have good thermal stability and are not prone to thermal runaway.
  • the energy density of the positive electrode active material of the first battery cell is greater than the energy density of the positive electrode active material of the second battery cell
  • the inner series battery has both high energy density and thermal stability.
  • each of the first battery cells independently includes a lithium-ion battery positive electrode active material; each of the second battery cells independently includes a sodium-ion battery positive electrode material.
  • the lithium-ion battery system has a higher energy density than the sodium-ion battery system.
  • the compaction density of the positive active material layer of the first battery cell is less than the compaction density of the positive active material layer of the second battery cell, so the internal resistance of the first battery cell is relatively large, and more heat is generated, which can increase the temperature of the battery cells at both ends, thereby increasing the energy density of the battery cells at both ends; while the internal resistance of the second battery cell is relatively small, and the heat is small, which can reduce the risk of thermal runaway of the middle battery cell. Therefore, the series battery has both high energy density and good thermal stability.
  • the energy density of the first battery cell is less than the energy density of the second battery cell.
  • a battery system with a smaller energy density has better mechanical safety.
  • the battery cells at both ends have a smaller energy density but better impact resistance, and the second battery cell has a higher energy density and average mechanical safety.
  • the internal series battery has both higher energy density and better mechanical safety.
  • the energy density of the negative electrode active material of the first battery cell is less than the energy density of the negative electrode active material of the second battery cell; negative electrode active materials with greater energy density generally have average mechanical strength, while negative electrode active materials with average energy density generally have better mechanical strength.
  • the negative electrode active material of each of the first battery cells independently includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon and lithium titanate; the theoretical energy density of the above negative electrode materials is general, but the mechanical strength is good.
  • the first battery cell adopts the above negative electrode material, and the battery cells at both ends of the series module have good mechanical safety and are not easy to deform and fail.
  • the negative electrode active material of each of the second battery cells independently includes at least one of a silicon-based material, a tin-based material and lithium metal.
  • the above negative electrode material has a high theoretical energy density, but a general mechanical strength.
  • the second battery cell adopts the above negative electrode material, which can ensure that the battery cell inside the series module has a high energy density, and the internal series battery thus has a high energy density.
  • the energy density of the positive electrode active material of the first battery cell is less than the energy density of the positive electrode active material of the second battery cell
  • the inner series battery has both high energy density and mechanical safety.
  • each of the first battery cells independently comprises a sodium ion battery positive electrode active material; each of the second battery cells independently comprises a lithium ion battery positive electrode material.
  • a lithium ion battery system has a higher energy density but relatively poor mechanical safety.
  • the inner series battery has both high energy density and mechanical safety.
  • the solid electrolyte layer of the second battery cell includes a high safety additive
  • the high-safety additive includes at least one of a phosphate ester and a fluorocarbonate
  • the phosphate ester includes at least one of trimethyl phosphate and triethyl phosphate;
  • the fluorinated carbonate includes at least one of methyl difluoroacetate and ethyl difluoroacetate.
  • High-safety additives can improve the cycle stability and thermal stability of secondary batteries.
  • the temperature inside the series module is usually higher than the temperature at both ends.
  • the battery cells inside the series module have better cycle stability and thermal stability, thereby reducing the overall thermal runaway risk of the internal series batteries and improving the cycle stability of the internal series batteries.
  • the ionic conductivity of the solid electrolyte of the first battery cell at 25°C is greater than 1 ⁇ 10 -3 S/cm; the ionic conductivity of the solid electrolyte of the second battery cell at 25°C is ⁇ 1 ⁇ 10 -3 S/cm.
  • the temperature inside the series module is usually higher than the temperature at both ends.
  • the present application also provides an electrical device, including the internal series battery of the first aspect.
  • the battery cells of the internal series battery are connected in series through an intermediate current collector, have a low internal resistance, high energy density and power density, and can be used as a power source for various electrical devices to meet the power needs of the electrical devices.
  • FIG1 is a schematic diagram of the structure of an inner series battery in one embodiment of the present application.
  • FIG2 is a schematic structural diagram of an inner series connection battery according to an embodiment of the present application.
  • FIG3 is a schematic diagram of an electrical device using internally connected series batteries as a power source according to an embodiment of the present application
  • an embodiment of the present application provides an inner series battery 1 , including: a series module 10 , a positive electrode current collector 20 , and a negative electrode current collector 30 .
  • the series module 10 includes a battery cell 110 and an intermediate current collector 120 .
  • the number of battery cells 110 is ⁇ 3. It can be understood that, according to the requirements for energy density and power density of the internally-connected series batteries 1, the number of battery cells 110 is 3, 4, 5, 6 or more.
  • Each battery cell 110 includes a stacked positive electrode active material layer 111, a solid electrolyte layer 112, and a negative electrode active material layer 113.
  • An intermediate current collector 120 is disposed between two adjacent battery cells 110, and the two adjacent battery cells 110 are connected in series via the intermediate current collector 120.
  • the adjacent battery cells 110 are connected in series via the intermediate current collector 120, which has the advantages of modularization, efficient stacking manufacturing, low internal resistance, and low cost compared to conventional external series battery cells.
  • the positive electrode current collector 20 is located at one end of the series module 10 and is electrically connected to the positive electrode active material layers of the battery cells 110 at the end.
  • the negative electrode current collector 30 is located at the other end of the series module 10 and is electrically connected to the negative electrode active material layer of the battery cell 110 at the end.
  • the battery unit 110 includes a first battery unit 110a and a second battery unit 110b.
  • the energy density of the first battery unit 110a is the same as the energy density of any battery unit at both ends of the series module.
  • the energy density of the second battery unit 110b is different from the energy density of the battery units at both ends of the series module.
  • the battery cells 110 are connected in series via the intermediate current collector 120.
  • the internal series battery 1 has both high energy density and good safety performance.
  • the positive electrode active material layer includes a positive electrode active material.
  • the positive electrode active material when the battery cell is a lithium-ion battery, may be a positive electrode active material for lithium-ion batteries known in the art.
  • the positive electrode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • lithium transition metal oxides may include, but are not limited to , lithium cobalt oxide (such as LiCoO2 ), lithium nickel oxide (such as LiNiO2 ), lithium manganese oxide (such as LiMnO2 , LiMn2O4 ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi1 / 3Co1 / 3Mn1 / 3O2 (also referred to as NCM333 ), LiNi0.5Co0.2Mn0.3O2 (also referred to as NCM523 ) , LiNi0.5Co0.25Mn0.25O2 (also referred to as NCM211 ) , LiNi0.6Co0.2Mn0.2O2 (also referred to as NCM622 ), LiNi0.8Co0.1Mn0.1O2 (also referred to as NCM811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05
  • lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate and carbon
  • the positive electrode active material when the battery cell is a sodium ion battery, may be a positive electrode active material for a sodium ion battery known in the art.
  • the positive electrode active material may be used alone or in combination of two or more.
  • the positive electrode active material may be selected from sodium iron composite oxide (NaFeO 2 ), sodium cobalt composite oxide (NaCoO 2 ), sodium chromium composite oxide (NaCrO 2 ), sodium manganese composite oxide (NaMnO 2 ), sodium nickel composite oxide (NaNiO 2 ), sodium nickel titanium composite oxide (NaNi 1/2 Ti 1/2 O 2 ), sodium nickel manganese composite oxide (NaNi 1/2 Mn 1/2 O 2 ), sodium iron manganese composite oxide (Na 2/3 Fe 1/3 Mn 2/3 O 2 ), sodium nickel cobalt manganese composite oxide (NaNi 1/3 Co 1/3 Mn 1/3 O 2 ), sodium iron phosphate (NaFePO 4 ), sodium manganese phosphate (NaMn P O 4 ), sodium cobalt phosphate (NaCoPO 4 ), Prussian blue materials, polyanion materials (phosphates, fluorophosphates, pyrophosphates, sulfates), etc., but the present application is not
  • the positive electrode active material layer may further include a binder.
  • the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-tetrafluoroethylene-propylene terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer
  • the positive electrode active material layer may further include a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the negative electrode active material layer includes a negative electrode active material.
  • the negative electrode active material may be a negative electrode active material for a battery known in the art.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative electrode active material layer may further include a binder.
  • the binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode active material layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • a conductive agent which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode active material layer may further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).
  • a thickener eg, sodium carboxymethyl cellulose (CMC-Na)
  • the solid electrolyte layer plays a role in conducting ions between the positive electrode active material layer and the negative electrode active material layer.
  • the solid electrolyte layer includes a polymer body and an electrolyte salt.
  • the mass ratio of the polymer body to the electrolyte salt is 20-80:80-20.
  • the polymer body can be selected from at least one of polyether polymers, polyolefin polymers, polynitrile polymers, and polycarboxylate polymers.
  • polyether polymers include at least one of polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene glycol (PEG), polyethylene glycol dimethyl ether (PEGDME) and polysiloxane.
  • Polyolefin polymers include at least one of polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polytetrafluoroethylene (PTFE) and polyvinyl chloride (PVC).
  • Polynitrile polymers include at least one of polyacrylonitrile (PAN) and polytripolyamide.
  • Polycarboxylate polymers include at least one of polymethyl methacrylate (PMMA) and polymethyl acrylate (PMA).
  • Polycarbonate polymers include at least one of polypropylene carbonate (PC) and polyethylene carbonate (PEC).
  • the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate and lithium tetrafluorooxalatophosphate.
  • the intermediate current collector may be a metal foil or a composite current collector.
  • a stainless steel foil or a titanium foil may be used as the metal foil.
  • an aluminum foil may also be used as the intermediate current collector.
  • the composite current collector may include a first metal layer and a second metal layer.
  • the first metal layer includes aluminum, aluminum alloy, etc.
  • the second metal layer includes copper, copper alloy, etc.
  • one side of the first metal layer of the intermediate current collector is close to the positive electrode active material layer of an adjacent battery cell, and one side of the second metal layer of the intermediate current collector is close to the negative electrode active material layer of another adjacent battery cell.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • aluminum foil may be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • a metal foil a copper foil may be used.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the ratio of the number of second battery cells to the total number of battery cells is (1-2): 3.
  • the number of second battery cells is within the above range, the energy density and safety performance of the inner series battery can be reasonably adjusted, and the overall performance of the inner series battery is better.
  • the temperature of the battery cells inside the inner series battery 1 will be higher than that of the battery cells at both ends, so the energy density and dynamic performance of the internal battery cells are relatively better; but at the same time, the risk of thermal runaway of the internal battery cells is also higher.
  • the energy density of the first battery cell 110a is greater than the energy density of the second battery cell 110b.
  • a battery system with a larger energy density has relatively poor thermal stability and a greater risk of thermal failure.
  • the energy density of the first battery cell 110a is greater than the energy density of the second battery cell 110b, which is beneficial to the theoretical energy density of the inner series battery 1.
  • the inner series battery 1 has a higher energy density, better kinetic performance and better thermal stability.
  • the energy density of the negative electrode active material of the first battery cell 110a is greater than the energy density of the negative electrode active material of the second battery cell 110b; negative electrode active materials with greater energy density generally have average thermal stability, while negative electrode active materials with average energy density generally have better thermal stability.
  • the inner series battery 1 has both higher energy density and better thermal stability.
  • the negative electrode active material of each first battery cell 110a independently includes at least one of a silicon-based material, a tin-based material and lithium metal; the above-mentioned negative electrode active material has a high theoretical energy density, but the thermal stability of the material is general.
  • the first battery cell 110a adopts the above-mentioned negative electrode active material, and the battery cells 110 at both ends of the series module 10 have a high energy density.
  • the inner series battery 1 can improve the energy density while taking into account thermal stability.
  • the negative electrode active material of each second battery cell 110b independently includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon and lithium titanate.
  • the theoretical energy density of the above negative electrode active materials is average, but they have good thermal stability.
  • the use of the above negative electrode active materials in the second battery cell 110b can ensure that the battery cells inside the series module 10 have good thermal stability and are not prone to thermal runaway.
  • the energy density of the positive electrode active material of the first battery cell 110a is greater than the energy density of the positive electrode active material of the second battery cell 110b.
  • the energy density of positive electrode active materials such as LiNi x Co y Mn z O 2 and lithium cobalt oxide is relatively high, while the energy density of positive electrode active materials such as LiFe a Mn b PO 4 , Li 3 V 2 (PO 4 ) 3 and lithium manganese oxide is relatively low.
  • the inner series battery 1 has both high energy density and thermal stability.
  • the energy density of the positive electrode active material of the first battery cell 110a is greater than that of the positive electrode active material of the second battery cell 110b.
  • the inner series battery 1 has both high energy density and thermal stability.
  • each first battery cell 110a independently includes a lithium-ion battery positive electrode active material; each second battery cell 110b independently includes a sodium-ion battery positive electrode material.
  • the lithium-ion battery system has a higher energy density than the sodium-ion battery system.
  • the inner series battery 1 has a higher energy density while taking into account safety performance.
  • LiNi x Co y Mn z O 2 material has a higher energy density, and the compaction density of the positive active material layer of the first battery cell 110a is less than the compaction density of the positive active material layer of the second battery cell 110b.
  • the internal resistance of the first battery cell 110a is relatively large, and the heat is more, which can increase the temperature of the battery cells 110 at both ends, thereby increasing the energy density of the battery cells 110 at both ends; while the internal resistance of the second battery cell 110b is relatively small, and the heat is less, which can reduce the thermal runaway risk of the middle battery cell 110. Therefore, the inner series battery 1 has both higher energy density and better thermal stability.
  • the positive electrode active material LiNi x Co y Mn z O 2 of each first battery cell 110a includes single crystal particles and polycrystalline particles; the mass ratio of the single crystal particles to the polycrystalline particles is (1:9) to (4:6), and can be optionally (1.5:8.5) to (2.5:7.5); the positive electrode active material LiNi x Co y Mn z O 2 of each second battery cell 110b includes single crystal particles and polycrystalline particles; the mass ratio of the single crystal particles to the polycrystalline particles is less than 1:9 or greater than 4:6.
  • the inner series battery 1 has an increased energy density by connecting a plurality of battery cells 110 in series. However, once the battery is damaged by an impact, the danger is also greater. Therefore, the mechanical safety requirements for the inner series battery 1 are also high.
  • the energy density of the first battery cell 110a is less than the energy density of the second battery cell 110b.
  • a battery system with a smaller energy density has better mechanical safety.
  • the battery cells 110 at both ends have a smaller energy density, but better impact resistance, and the second battery cell 110b has a higher energy density and average mechanical safety.
  • the internal series battery 1 has both higher energy density and better mechanical safety.
  • the energy density of the negative electrode active material of the first battery cell 110a is less than the energy density of the negative electrode active material of the second battery cell 110b; negative electrode active materials with greater energy density generally have average mechanical strength, while negative electrode active materials with average energy density generally have better mechanical strength.
  • the inner series battery 1 has both higher energy density and better mechanical safety.
  • the negative electrode active material of each first battery cell 110a independently includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon and lithium titanate.
  • the theoretical energy density of the above negative electrode materials is average, but the mechanical strength is good.
  • the first battery cell 110a adopts the above negative electrode material, and the battery cells at both ends of the series module 10 have good mechanical safety and are not easy to deform and fail.
  • the negative electrode active material of each second battery cell 110b independently includes at least one of a silicon-based material, a tin-based material and lithium metal.
  • the above negative electrode material has a high theoretical energy density, but a general mechanical strength.
  • the second battery cell 110b uses the above negative electrode material to ensure that the battery cell 110 inside the series module 10 has a high energy density, and the internal series battery 1 thus has a high energy density.
  • the energy density of the positive active material of the first battery cell 110 a is less than the energy density of the positive active material of the second battery cell 110 b ;
  • Positive electrode active materials such as LiNixCoyMnzO2 and lithium cobaltate have high energy density but average mechanical safety, while positive electrode active materials such as LiFeaMnbPO4 , Li3V2 ( PO4 ) 3 and lithium manganate have low energy density but good mechanical safety.
  • the inner series battery 1 By reasonably designing the energy density of the positive electrode active materials in the first battery cell 110a and the second battery cell 110b, the inner series battery 1 has both high energy density and mechanical safety.
  • the energy density of the positive electrode active material of the first battery cell 110a is less than that of the positive electrode active material of the second battery cell 110b.
  • the inner series battery 1 has both high energy density and mechanical safety.
  • the inner series battery 1 has both high energy density and mechanical safety.
  • each first battery cell 110a independently includes a sodium ion battery positive electrode active material; each second battery cell 110b independently includes a lithium ion battery positive electrode material.
  • a lithium ion battery system has a higher energy density but relatively poor mechanical safety.
  • the inner series battery 1 has both high energy density and mechanical safety.
  • the solid electrolyte layer 112 of the second battery cell 110b includes a high-safety additive.
  • the high-safety additive can improve the cycle stability and thermal stability of the secondary battery.
  • the temperature inside the series module 10 is usually higher than the temperature at both ends.
  • the high safety additive includes at least one of phosphate ester and fluorocarbonate.
  • the phosphate ester includes at least one of trimethyl phosphate and triethyl phosphate.
  • the fluorinated carbonate comprises at least one of methyl difluoroacetate and ethyl difluoroacetate.
  • the ionic conductivity of the solid electrolyte layer of the first battery cell 110a at 25°C is greater than 1 ⁇ 10 -3 S/cm; the ionic conductivity of the solid electrolyte layer of the second battery cell 110b at 25°C is ⁇ 1 ⁇ 10 -3 S/cm.
  • the temperature inside the series module is usually higher than the temperature at both ends, resulting in the dynamic performance of the battery cells at both ends being usually inferior to the dynamic performance of the battery cells inside the series module.
  • the ionic conductivity of the solid electrolyte layer can be tested by the following method: (1) Cut the solid electrolyte layer into discs with a diameter of 19 mm and dry them for later use; (2) Assemble the discs into a "standard stainless steel gasket/electrolyte/standard stainless steel gasket" CR2032 button-type experimental battery in an inert gas glove box, package the battery at a pressure of 5 MPa, and store it at 25°C for 1 hour; (3) Use an electrochemical workstation to measure the corresponding Nyquist spectrum according to the alternating current impedance method (EIS).
  • EIS alternating current impedance method
  • the ambient temperature is T (unit °C), the test frequency range is 1MHz ⁇ 100mHz, and the perturbation voltage is 10mV; (4) After the test, disassemble the battery, measure the thickness L (unit cm) of the disc, the area S (unit cm2 ) of the standard gasket, and fit the Nyquist spectrum to obtain the resistance R (unit ⁇ ). According to the formula The ionic conductivity ⁇ (unit: S/cm) of the solid electrolyte at temperature T is calculated.
  • the present application also provides an electrical device, which includes the internal series battery provided in the present application.
  • the internal series battery can be used as a power source for the electrical device, or as an energy storage unit for the electrical device.
  • the electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.
  • FIG3 is an example of an electric device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.
  • Another example of a device may be a mobile phone, a tablet computer, a laptop computer, etc.
  • the positive electrode slurry is evenly coated on one side of the intermediate current collector stainless steel foil, and the negative electrode slurry is evenly coated on the other side of the intermediate current collector; after drying and cold pressing, the composite pole piece is obtained, which includes a stacked positive electrode active material layer, an intermediate current collector and a negative electrode active material layer.
  • Preparation of single-sided positive electrode sheet evenly apply the positive electrode slurry on one side of the positive electrode collector aluminum foil; after drying and cold pressing, the single-sided positive electrode sheet is obtained.
  • Preparation of single-sided negative electrode sheet evenly apply negative electrode slurry on one side of the negative electrode collector copper foil; after drying and cold pressing, a single-sided negative electrode sheet is obtained.
  • Preparation of solid electrolyte layer The polymer body, electrolyte salt and solvent are mixed evenly at 25°C, and then dried and hot-pressed to obtain a solid electrolyte layer.
  • Preparation of inner series battery According to the order of single-sided positive electrode sheet, solid electrolyte layer, composite electrode sheet, solid electrolyte layer, composite electrode sheet, ..., composite electrode sheet, solid electrolyte layer, single-sided negative electrode sheet, and according to the design of inner series battery, the prepared single-sided positive electrode sheet, solid electrolyte layer, composite electrode sheet and single-sided negative electrode sheet are stacked and roll-formed to obtain battery assembly.
  • the battery assembly is placed in a packaging shell, and after welding, packaging and other processes, an inner series battery is made.
  • the stacked positive electrode active material layer, solid electrolyte layer and negative electrode active material layer form a battery cell, and there are 4 battery cells in the inner series battery.
  • the inner series battery includes a stacked first battery cell, a second battery cell, a second battery cell and a first battery cell, that is, the first battery cell is at both ends of the series module, and the second battery cell is a battery cell inside the series module.
  • Thermal stability test The temperature at which the internal series battery fails (fire, explosion) is obtained through hot box test. The specific steps are: with 25°C as the initial temperature, the internal series battery is heated to 100°C at 5°C/min and left to stand for 30 minutes; then the temperature is increased at 5°C/min and kept at 5°C for 30 minutes until the internal series battery fails, and the failure time and the temperature of the internal battery unit when the internal series battery fails are recorded.
  • the mechanical safety test tests the failure deformation by squeezing the internal series battery.
  • a semi-cylinder with a radius of 75mm is used to press one end of the internal series battery at a squeezing speed of 2mm/s. The squeezing is continued until the internal series battery fails (caught fire or exploded). The displacement of the semi-cylinder is recorded at this time.
  • the failure deformation (%) displacement of the semi-cylinder / length of the internal series battery along the stacking direction of the battery cells.
  • the internal series-connected batteries are charged at 0.33C to the upper voltage limit, then switched to constant voltage charging, and stopped charging when the charging current drops to 0.05C. After standing for 30 minutes, the batteries are discharged at 2C to the lower voltage limit, and the discharge capacity C1 (Ah) is recorded. The rate performance is expressed by the capacity retention rate, which is C1/C0 (%).
  • the surfaces of the positive electrode active layer and the negative electrode active material layer are respectively attached to the current collector to obtain a conventional secondary battery.
  • the performance of a single battery cell can also be tested by the method in the above test section.
  • the composition of the NCM811 positive electrode active material layer is: NCM811, PVDF and conductive carbon black in a mass ratio of 97:2:1.
  • the composition of the NCM333 positive electrode active material layer is: NCM333, PVDF and conductive carbon black in a mass ratio of 97:2:1.
  • the composition of the LFP positive electrode active material layer is: LFP, PVDF and conductive carbon black in a mass ratio of 97:2:1.
  • the composition of the NCM811 positive electrode active material layer (single crystal, polycrystalline mass ratio of 8:2) is: single crystal NCM811, polycrystalline NCM811, PVDF and conductive carbon black in a mass ratio of 77.6:19.4:2:1, and the compacted density is 3.3g/ cm3 .
  • the composition of the positive electrode active material layer of NCM811 (single crystal and polycrystalline mass ratio is 2:8) is: single crystal NCM811, polycrystalline NCM811, PVDF and conductive agent carbon black with a mass ratio of 19.4:77.6:2:1, and the compaction density is 3.4g/ cm3 .
  • the composition of the positive electrode active material layer of Na2MnFe (CN) 6 is: Na2MnFe (CN) 6 , PVDF and conductive agent carbon black with a mass ratio of 97:2:1.
  • the composition of the silicon-based negative electrode active material layer is: silicon-based material, conductive agent carbon black, binder styrene butadiene rubber (SBR), thickener sodium hydroxymethyl cellulose (CMC-Na) with a mass ratio of 97:0.5:1.25:1.25.
  • the composition of the graphite negative electrode active material layer is: graphite, conductive agent carbon black, binder styrene butadiene rubber (SBR), thickener sodium hydroxymethyl cellulose (CMC-Na) with a mass ratio of 97:0.5:1.25:1.25.
  • the composition of the hard carbon negative electrode active material layer is: hard carbon, conductive agent carbon black, binder styrene butadiene rubber (SBR), thickener sodium hydroxymethyl cellulose (CMC-Na) in a mass ratio of 97:0.5:1.25:1.25.
  • the composition of the PEO-LiTFSI solid electrolyte layer is: PEO and LiTFSI in a mass ratio of 25:75.
  • the composition of the Na- ⁇ -Al 2 O 3 solid electrolyte layer is: 100% Na- ⁇ -Al 2 O 3 by mass percentage.
  • the energy density of the inner series battery in Examples 1-1 to 1-12 is 280Wh/kg to 370Wh/kg, and the internal temperature of the inner series battery when it fails is 130°C to 190°C.
  • the inner series battery has both high energy density and good thermal stability.
  • the composition of the first battery cell and the second battery cell is the same, and the obtained inner series battery is difficult to take into account both high energy density and good thermal stability.
  • the composition of the NCM811 positive electrode active material layer is: NCM811, PVDF and conductive agent carbon black in a mass ratio of 97:2:1.
  • the composition of the NCM333 positive electrode active material layer is: NCM333, PVDF and conductive agent carbon black in a mass ratio of 97:2:1.
  • the composition of the LFP positive electrode active material layer is: LFP, PVDF and conductive agent carbon black in a mass ratio of 97:2:1.
  • the composition of the Na 2 MnFe(CN) 6 positive electrode active material layer is: Na 2 MnFe(CN) 6 , PVDF and conductive agent carbon black in a mass ratio of 97:2:1.
  • the composition of the silicon-based negative electrode active material layer is: silicon-based material, conductive agent carbon black, binder styrene butadiene rubber (SBR), thickener sodium carboxymethyl cellulose (CMC-Na) in a mass ratio of 97:0.5:1.25:1.25.
  • the composition of the graphite negative electrode active material layer is: graphite, conductive agent carbon black, binder styrene butadiene rubber (SBR), thickener sodium hydroxymethyl cellulose (CMC-Na) in a mass ratio of 97:0.5:1.25:1.25.
  • the composition of the hard carbon negative electrode active material layer is: hard carbon, conductive agent carbon black, binder styrene butadiene rubber (SBR), thickener sodium hydroxymethyl cellulose (CMC-Na) in a mass ratio of 97:0.5:1.25:1.25.
  • the composition of the PEO-LiTFSI solid electrolyte layer is: PEO and LiTFSI in a mass ratio of 25:75.
  • the composition of the Na- ⁇ -Al 2 O 3 solid electrolyte layer is: 100% Na- ⁇ -Al 2 O 3 by mass percentage.
  • the energy density of the inner series battery of Examples 2-1 to 2-10 is 262Wh/kg to 368Wh/kg, and the failure deformation is 23% to 40%.
  • the inner series battery has both high energy density and good mechanical safety. Compared with Comparative Examples 1-1 to 1-5, the inner series battery of Examples 2-1 to 2-10 has better comprehensive performance.
  • Example 3-4 The difference between the inner series cells of Examples 3-1 to 3-4 and Example 1-1 is that the composition and ionic conductivity of the solid electrolyte layer are different.
  • the design of the inner series cells of Examples 3-1 to 3-4 refers to Table 3.
  • the composition of the PEO-LiTFSI solid electrolyte layer with a conductivity of 1 mS/cm is: PEO and LiTFSI in a mass ratio of 25:75.
  • the composition of the PEO-LiTFSI solid electrolyte layer with a conductivity of 3 mS/cm is: plasticizer EC, PEO, LiTFSI in a mass ratio of 20:20:60.
  • Example 3-2 From the relevant data in Table 3, it can be seen from Example 3-2 that the ionic conductivity of the solid electrolyte layer has an impact on the energy density, rate performance, and thermal stability of the inner series battery.
  • the ionic conductivity of the solid electrolyte layer is large, and the energy density and rate performance of the inner series battery are better, but the thermal stability of the inner series battery decreases.
  • high-safety additives can improve the thermal stability of the inner series battery.
  • the ionic conductivity of the solid electrolyte layer of the first battery cell is 3mS/cm, and no high-safety additives are added.
  • the ionic conductivity of the solid electrolyte layer of the second battery cell is 1mS/cm, and ethyl difluoroacetate is added.
  • the energy density of the prepared inner series battery is 345Wh/kg, the rate performance is 83%, and the internal temperature of the inner series battery is 200°C when it fails.
  • the overall performance of the inner series battery of Example 3-1 is better.

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Abstract

本申请提供了一种内串联电池，包括串联模块、正极集流体及负极集流体。串联模块包括电池单元及中间集流体。电池单元的数量≥3。各电池单元包括层叠设置的正极活性材料层、固态电解质层及负极活性材料层。中间集流体设于相邻的两电池单元之间，且相邻的两电池单元以中间集流体串联。正极集流***于串联模块的一端且与该端部的电池单元的正极活性材料层电连接。负极集流***于串联模块的另一端且与该端部的电池单元的负极活性材料层电连接。电池单元包括第一电池单元及第二电池单元。第一电池单元的能量密度与位于串联模块两端的任一电池单元的能量密度相同。第二电池单元的能量密度与位于串联模块两端的电池单元的能量密度不同。

Description

内串联电池及用电装置 技术领域
本申请涉及二次电池领域，具体涉及一种内串联电池及用电装置。
背景技术
随着电动汽车、储能***等快速发展，市场上对于二次电池的能量密度及功率密度的要求越来越高。传统技术中通常将多个二次电池串联以达到提升能量密度及功率密度的需求。然而多个二次电池串联的热失控风险较高，且对电池的机械安全性要求较高；传统的串联电池难以同时兼顾能量密度及安全性能的需求。
发明内容
基于上述问题，本申请提供一种兼具较高的能量密度及较好的安全性能的内串联电池及用电装置。
本申请的一个方面，提供了一种内串联电池，包括：
串联模块，包括电池单元及中间集流体；所述电池单元的数量≥3，各所述电池单元包括层叠设置的正极活性材料层、固态电解质层及负极活性材料层；所述中间集流体设置于相邻的两个所述电池单元之间，且相邻的两个所述电池单元以所述中间集流体串联；
正极集流体，位于所述串联模块的一端且与该端部的电池单元的正极活性材料层电连接；以及
负极集流体，位于所述串联模块的另一端且与该端部的电池单元的负极活性材料层电连接；
其中，所述电池单元包括第一电池单元及第二电池单元；所述第一电池单元的能量密度与位于所述串联模块两端的任一电池单元的能量密度相同；所述第二电池单元的能量密度与位于所述串联模块两端的电池单元的能量密度不同。
本申请实施方式的内串联电池中，电池单元之间通过中间集流体串联，通过能量密度不同的第一电池单元及第二电池单元的合理设计，内部串联电池兼具较高的能量密度及较好的安全性能。
在其中一些实施例中，所述第二电池单元的数量与所述电池单元总数量的比值为(1～2)：3。第二电池单元的数量在上述范围内，可以合理调节内串联电池的能量密度及安全性能，内串联电池的综合性能较佳。
在其中一些实施例中，所述第一电池单元的能量密度大于所述第二电池单元的能量密度。通常地，能量密度较大的电池体系的热稳定性相对较差，热失效风险较大。第一电池单元的能量密度大于第二电池单元的能量密度，有利于内串联电池理论能量密度发挥，内串联电池兼具较高的能量密度、较好的动力学性能及较佳的热稳定性。
在其中一些实施例中，所述第一电池单元的负极活性材料的能量密度大于所述第二电池单元的负极活性材料的能量密度；能量密度较大的负极活性材料通常热稳定性一般，而能量密度一般的负极活性材料通常具有较好的热稳定性。通过对电池单元负极活性材料的合理选择设计，内串联电池兼具较高的能量密度及较佳的热稳定性。
可选地，各所述第一电池单元的负极活性材料独立地包括硅基材料、锡基材料及锂金属中的至少一种；上述负极活性材料具有较高的理论能量密度，但材料热稳定性一般，第一电池单元采用上述负极活性材料，串联模块两端的电池单元具有较高的能量密度，内串联电池能够在兼顾热稳定性的同时改善能量密度。
可选地，各所述第二电池单元的负极活性材料独立地包括人造石墨、天然石墨、软碳、硬碳及钛酸锂 中的至少一种。上述负极活性材料的理论能量密度一般，但具有较好的热稳定性，第二电池单元采用上述负极活性材料能够保证串联模块内部的电池单元具有较好的热稳定性，不易发生热失控。
在其中一些实施例中，所述第一电池单元的正极活性材料的能量密度大于所述第二电池单元的正极活性材料的能量密度；
可选地，各所述第一电池单元的正极活性材料独立地包括LiNi xCo yMn zO 2及钴酸锂中的至少一种，其中x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1；各所述第二电池单元的正极活性材料独立地包括LiFe aMn bPO 4、Li 3V 2(PO 4) 3及锰酸锂中的至少一种，其中a+b＝1，0≤a≤1，0≤b≤1；
可选地，各所述第一电池单元的正极活性材料独立地包括LiNi xCo yMn zO 2，其中x+y+z＝1，0.8≤x＜1，0＜y＜0.2，0＜z＜0.2；各所述第二电池单元的正极活性材料独立地包括LiNi xCo yMn zO 2，其中x+y+z＝1，0＜x＜0.8，0＜y＜1，0＜z＜1。
通过合理设计第一电池单元及第二电池单元中正极活性材料的能量密度，内串联电池兼具较高的能量密度及热稳定性。
在其中一些实施例中，各所述第一电池单元独立地包括锂离子电池正极活性材料；各所述第二电池单元独立地包括钠离子电池正极材料。锂离子电池体系相对于钠离子电池体系具有较高的能量密度，通过上述正极活性材料的合理选择设计，内串联电池在兼顾安全性能的同时具有较高的能量密度。
在其中一些实施例中，各所述第一电池单元及各所述第二电池单元的正极活性材料独立地包括LiNi xCo yMn zO 2，其中x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1；所述第一电池单元的正极活性材料层的压实密度小于所述第二电池单元的正极活性材料层的压实密度。第一电池单元的正极活性材料层的压实密度小于第二电池单元正极活性材料层的压实密度，故而第一电池单元的内阻相对较大，发热较多，能够提升两端的电池单元的温度，从而提升两端的电池单元的能量密度；而第二电池单元的内阻相对较小，发热较小，能够降低中间的电池单元的热失控风险。因此，串联电池兼具较高的能量密度及较好的热稳定性。
在其中一些实施例中，所述第一电池单元的能量密度小于所述第二电池单元的能量密度。通常地，能量密度较小的电池体系具有较好的机械安全性，通过第一电池单元、第二电池单元能量密度的合理设计，位于两端的电池单元具有较小的能量密度，但耐冲击性能较好，第二电池单元具有较高的能量密度，其机械安全性一般。通过电池单元的合理选择，内串联电池兼具较高的能量密度及较好的机械安全性。
在其中一些实施例中，所述第一电池单元的负极活性材料的能量密度小于所述第二电池单元的负极活性材料的能量密度；能量密度较大的负极活性材料通常机械强度一般，而能量密度一般的负极活性材料通常具有较好的机械强度。通过对电池单元负极活性材料的合理选择设计，内串联电池兼具较高的能量密度及较好的机械安全性。
可选地，各所述第一电池单元的负极活性材料独立地包括人造石墨、天然石墨、软碳、硬碳及钛酸锂中的至少一种；上述负极材料的理论能量密度一般，而机械强度较好，第一电池单元采用上述负极材料，串联模块两端的电池单元具有较好的机械安全性，不易变形失效。
可选地，各所述第二电池单元的负极活性材料独立地包括硅基材料、锡基材料及锂金属中的至少一种。上述负极材料的理论能量密度较高，而机械强度一般，第二电池单元采用上述负极材料，能够保证串联模块内部的电池单元具有较高的能量密度，内串联电池从而具有较高的能量密度。
在其中一些实施例中，所述第一电池单元的正极活性材料的能量密度小于所述第二电池单元的正极活性材料的能量密度；
可选地，各所述第一电池单元的正极活性材料独立地包括LiFe aMn bPO 4、Li 3V 2(PO 4) 3及锰酸锂中的至少一种，其中a+b＝1，0≤a≤1，0≤b≤1；各所述第二电池单元的正极活性材料独立地包括LiNi xCo yMn zO 2 及钴酸锂中的至少一种，其中x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1；
可选地，各所述第一电池单元的正极活性材料独立地包括LiNi xCo yMn zO 2，其中x+y+z＝1，0＜x＜0.8，0＜y＜1，0＜z＜1；各所述第二电池单元的正极活性材料独立地包括LiNi xCoyMn zO 2，其中x+y+z＝1，0.8≤x＜1，0＜y＜0.2，0＜z＜0.2。
通过合理设计第一电池单元及第二电池单元中正极活性材料的能量密度，内串联电池兼具较高的能量密度及机械安全性。
在其中一些实施例中，各所述第一电池单元独立地包括钠离子电池正极活性材料；各所述第二电池单元独立地包括锂离子电池正极材料。锂离子电池体系相对于钠离子电池体系具有较高的能量密度但机械安全性相对较差，通过上述正极活性材料的合理选择设计，内串联电池兼具较高的能量密度及机械安全性。
在其中一些实施例中，其中，所述第二电池单元的固态电解质层包括高安全性添加剂；
可选地，所述高安全性添加剂包括磷酸酯及氟代碳酸酯中的至少一种；
可选地，所述磷酸酯包括磷酸三甲酯及磷酸三乙酯中的至少一种；
可选地，所述氟代碳酸酯包括二氟乙酸甲酯及二氟乙酸乙酯中的至少一种。
高安全性添加剂能够提升二次电池的循环稳定性及热稳定性，串联模块内部的温度通常高于两端的温度，通过在第二电池单元的固态电解质中添加高安全性添加剂，串联模块内部的电池单元具有较好的循环稳定性及而稳定性，从而降低了内串联电池整体的热失控风险，提升了内串联电池的循环稳定性。
在其中一些实施例中，所述第一电池单元的固态电解质在25℃的离子电导率＞1×10 -3S/cm；所述第二电池单元的固态电解质在25℃的离子电导率≤1×10 -3S/cm。串联模块内部的温度通常高于两端的温度，通过合理设计第一电池单元、第二电池单元的离子电导率，内串联电池的内阻较小，具有较好的倍率性能。
第二方面，本申请还提供了一种用电装置，包括上述第一方面的内串联电池。上述内串联电池电池单元之间通过中间集流体串联，具有较低的内阻、较高的能量密度及功率密度，能够作为各种用电装置的电源使用，满足用电装置的用电需求。
本申请的一个或多个实施例的细节在下面的附图和描述中提出，本申请的其它特征、目的和优点将从说明书、附图及权利要求书变得明显。
附图说明
图1为本申请一实施方式的内串联电池的结构示意图；
图2为本申请一实施方式的内串联电池的结构示意图；
图3为本申请一实施方式的内串联电池用作电源的用电装置的示意图；
附图标记说明：
1、内串联电池；10、串联模块；110、电池单元；110a、第一电池单元；110b、第二电池单元；111、正极活性材料层；112、固态电解质层；113、负极活性材料层；120、中间集流体；20、正极集流体；30、负极集流体。
为了更好地描述和说明这里公开的那些发明的实施例和/或示例，可以参考一副或多副附图。用于描述附图的附加细节或示例不应当被认为是对所公开的发明、目前描述的实施例和/或示例以及目前理解的这些发明的最佳模式中的任何一者的范围的限制。
具体实施方式
为了便于理解本申请，下面将参照相关附图对本申请进行更全面的描述。附图中给出了本申请的较佳实施例。但是，本申请可以以许多不同的形式来实现，并不限于本文所描述的实施例。相反地，提供这些实施例的目的是使对本申请的公开内容的理解更加透彻全面。
除非另有定义，本文所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同。本文中在本申请的说明书中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请。本文所使用的术语“和/或”包括一个或多个相关的所列项目的任意的和所有的组合。
参阅图1及图2，本申请一实施方式，提供了一种内串联电池1，包括：串联模块10、正极集流体20及负极集流体30。
串联模块10包括电池单元110及中间集流体120。
电池单元110的数量≥3。可以理解地，根据对内串联电池1的能量密度、功率密度的需求，电池单元110的数量为3、4、5、6或者更多。
各电池单元110包括层叠设置的正极活性材料层111、固态电解质层112及负极活性材料层113。中间集流体120设置于相邻的两个电池单元110之间，且相邻的两个电池单元110以中间集流体120串联。相邻的电池单元110通过中间集流体120串联，相比传统外串联的电池单体，具有可模块化、高效堆叠制造、低内阻、低成本等优势。
正极集流体20位于串联模块10的一端且与该端部的电池单元110的正极活性材料层电连接。
负极集流体30位于串联模块10的另一端且与该端部的电池单元110的负极活性材料层电连接。
其中，电池单元110包括第一电池单元110a及第二电池单元110b。第一电池单元110a的能量密度与位于串联模块两端的任一电池单元的能量密度相同。第二电池单元110b的能量密度与位于串联模块两端的电池单元的能量密度不同。
本申请实施方式的内串联电池1中，电池单元110之间通过中间集流体120串联，通过能量密度不同的第一电池单元110a及第二电池单元110b的合理设计，内部串联电池1兼具较高的能量密度及较好的安全性能。
正极活性材料层
正极活性材料层包括正极活性材料。
在其中一些实施例中，当电池单元为锂离子电池时，正极活性材料可采用本领域公知的用于锂离子电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。
在其中一些实施例中，当电池单元为钠离子电池时，正极活性材料可采用本领域公知的用于钠离子电池的正极活性材料。作为示例，正极活性材料可以仅单独使用一种，也可以将两种以上组合。其中，正极活性物质可选自钠铁复合氧化物(NaFeO 2)、钠钴复合氧化物(NaCoO 2)、钠铬复合氧化物(NaCrO 2)、钠锰复合 氧化物(NaMnO 2)、钠镍复合氧化物(NaNiO 2)、钠镍钛复合氧化物(NaNi 1/2Ti 1/2O 2)、钠镍锰复合氧化物(NaNi 1/2Mn 1/2O 2)、钠铁锰复合氧化物(Na 2/3Fe 1/3Mn 2/3O 2)、钠镍钴锰复合氧化物(NaNi 1/3Co 1/3Mn 1/3O 2)、钠铁磷酸化合物(NaFePO 4)、钠锰磷酸化合物(NaMn PO 4)、钠钴磷酸化合物(NaCoPO 4)、普鲁士蓝类材料、聚阴离子材料(磷酸盐、氟磷酸盐、焦磷酸盐、硫酸盐)等，但本申请并不限定于这些材料，本申请还可以使用其他可被用作钠离子电池正极活性物质的传统公知的材料。
在其中一些实施例中，正极活性材料层还可选地包括粘结剂。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在其中一些实施例中，正极活性材料层还可选地包括导电剂。作为示例，所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
负极活性材料层
负极活性材料层包括负极活性材料。
在其中一些实施例中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软碳、硬碳、硅基材料、锡基材料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在其中一些实施例中，负极活性材料层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在其中一些实施例中，负极活性材料层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在其中一些实施例中，负极活性材料层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
固态电解质层
固态电解质层在正极活性材料层和负极活性材料层之间起到传导离子的作用。在其中一些实施例中，固态电解质层包括聚合物本体和电解质盐。在一些实施例中，聚合物本体与电解质盐的质量比为20～80:80～20。
作为示例地，聚合物本体可选自聚醚类聚合物、聚烯烃类聚合物、聚腈类聚合物、聚羧酸酯类聚合物中的至少一种。其中，聚醚类聚合物包括聚环氧乙烷(PEO)、聚环氧丙烷(PPO)、聚乙二醇(PEG)、聚乙二醇二甲醚(PEGDME)及聚硅氧烷中的至少一种。聚烯烃类聚合物包括聚乙烯(PE)、聚丙烯(PP)、聚偏四氟乙烯(PVDF)、聚偏氟乙烯-六氟丙烯共聚物(PVDF-HFP)、聚四氟乙烯(PTFE)及聚氯乙烯(PVC)中的至少一种。聚腈类聚合物包括聚丙烯腈(PAN)及聚三聚腈胺中的至少一种。聚羧酸酯类聚合物包括聚甲基丙烯酸甲酯(PMMA)及聚丙烯酸甲酯(PMA)中的至少一种。聚碳酸酯类聚合物包括聚碳酸丙烯酯(PC)及聚亚乙基碳酸酯(PEC)中的至少一种。
作为示例地，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。
中间集流体
在其中一些实施例中，中间集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用不锈钢箔或者钛箔。对于钠离子电池体系的电池单元，中间集流体也可采用铝箔。
复合集流体可包括第一金属层及第二金属层。第一金属层包括铝、铝合金等。第二金属层包括铜、铜合金等。在串联模块中，中间集流体的第一金属层一侧靠近相邻的一个电池单元的正极活性材料层，中间集流体的第二金属层一侧靠近相邻的另一个电池单元的负极活性材料层。
正极集流体
在其中一些实施例中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
负极集流体
在其中一些实施例中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在其中一些实施例中，第二电池单元的数量与电池单元总数量的比值为(1～2)：3。第二电池单元的数量在上述范围内，可以合理调节内串联电池的能量密度及安全性能，内串联电池的综合性能较佳。
由于多个电池单元110串联，内串联电池1内部的电池单元相对于两端的电池单元的温度会更高，故而内部的电池单元的能量密度发挥及动力学性能相对更好；但与此同时，内部的电池单元的热失控风险也更高。
在其中一些实施例中，第一电池单元110a的能量密度大于第二电池单元110b的能量密度。通常地，能量密度较大的电池体系的热稳定性相对较差，热失效风险较大。第一电池单元110a的能量密度大于第二电池单元110b的能量密度，有利于内串联电池1理论能量密度发挥，内串联电池1兼具较高的能量密度、较好的动力学性能及较佳的热稳定性。
在其中一些实施例中，第一电池单元110a的负极活性材料的能量密度大于第二电池单元110b的负极活性材料的能量密度；能量密度较大的负极活性材料通常热稳定性一般，而能量密度一般的负极活性材料通常具有较好的热稳定性。通过对电池单元110负极活性材料的合理选择设计，内串联电池1兼具较高的能量密度及较佳的热稳定性。
可选地，各第一电池单元110a的负极活性材料独立地包括硅基材料、锡基材料及锂金属中的至少一种；上述负极活性材料具有较高的理论能量密度，但材料热稳定性一般，第一电池单元110a采用上述负极活性材料，串联模块10两端的电池单元110具有较高的能量密度，内串联电池1能够在兼顾热稳定性的同时改善能量密度。
可选地，各第二电池单元110b的负极活性材料独立地包括人造石墨、天然石墨、软碳、硬碳及钛酸锂中的至少一种。上述负极活性材料的理论能量密度一般，但具有较好的热稳定性，第二电池单元110b采用上述负极活性材料能够保证串联模块10内部的电池单元具有较好的热稳定性，不易发生热失控。
在其中一些实施例中，第一电池单元110a的正极活性材料的能量密度大于第二电池单元110b的正极活性材料的能量密度。通过合理设计第一电池单元110a及第二电池单元110b中正极活性材料的能量密度，内串联电池1兼具较高的能量密度及热稳定性。
可选地，各第一电池单元110a的正极活性材料独立地包括LiNi xCo yMn zO 2及钴酸锂中的至少一种，其中x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1；各第二电池单元110b的正极活性材料独立地包括LiFe aMn bPO 4、Li 3V 2(PO 4) 3及锰酸锂中的至少一种，其中a+b＝1，0≤a≤1，0≤b≤1。LiNi xCo yMn zO 2及钴酸锂等正极活性材料的能量密度较高，LiFe aMn bPO 4、Li 3V 2(PO 4) 3及锰酸锂等正极活性材料的能量密度较低，通过合理设计第一电池单元110a及第二电池单元110b中正极活性材料的能量密度，内串联电池1兼具较高的能量密度及热稳定性。
可选地，各第一电池单元110a的正极活性材料独立地包括LiNi xCo yMn zO 2，其中x+y+z＝1，0.8≤x＜1，0＜y＜0.2，0＜z＜0.2；各第二电池单元110b的正极活性材料独立地包括LiNi xCo yMn zO 2，其中x+y+z＝1，0＜x＜0.8，0＜y＜1，0＜z＜1。通过第一电池单元110a采用高镍的LiNi xCo yMn zO 2，而第二电池单元110b采用低镍的LiNi xCo yMn zO 2，第一电池单元110a正极活性材料的能量密度大于第二电池单元110b正极活性材料的能量密度。通过合理设计第一电池单元110a及第二电池单元110b中正极活性材料的能量密度，内串联电池1兼具较高的能量密度及热稳定性。
在其中一些实施例中，各第一电池单元110a独立地包括锂离子电池正极活性材料；各第二电池单元110b独立地包括钠离子电池正极材料。锂离子电池体系相对于钠离子电池体系具有较高的能量密度，通过上述正极活性材料的合理选择设计，内串联电池1在兼顾安全性能的同时具有较高的能量密度。
在其中一些实施例中，各第一电池单元110a及各第二电池单元110b的正极活性材料独立地包括LiNi xCo yMn zO 2，其中x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1；第一电池单元110a的正极活性材料层的压实密度小于第二电池单元110b的正极活性材料层的压实密度。LiNi xCo yMn zO 2材料具有较高的能量密度，第一电池单元110a的正极活性材料层的压实密度小于第二电池单元110b正极活性材料层的压实密度，故而第一电池单元110a的内阻相对较大，发热较多，能够提升两端的电池单元110的温度，从而提升两端的电池单元110的能量密度；而第二电池单元110b的内阻相对较小，发热较小，能够降低中间的电池单元110的热失控风险。因此，内串联电池1兼具较高的能量密度及较好的热稳定性。进一步地，各第一电池单元110a的正极活性材料LiNi xCo yMn zO 2包括单晶颗粒及多晶颗粒；单晶颗粒与多晶颗粒的质量比为(1:9)～(4:6)，可选为(1.5:8.5)～(2.5:7.5)；各第二电池单元110b的正极活性材料LiNi xCo yMn zO 2包括单晶颗粒及多晶颗粒；单晶颗粒与多晶颗粒的质量比小于1:9或者大于4:6。
内串联电池1通过多个电池单元110串联提升了能量密度，然而一旦被冲击破坏的危害性也较大，故而对内串联电池1的机械安全性要求也较高。
在其中一些实施例中，第一电池单元110a的能量密度小于第二电池单元110b的能量密度。通常地，能量密度较小的电池体系具有较好的机械安全性，通过第一电池单元110a、第二电池单元110b能量密度的合理设计，位于两端的电池单元110具有较小的能量密度，但耐冲击性能较好，第二电池单元110b具有较高的能量密度，其机械安全性一般。通过电池单元110的合理选择，内串联电池1兼具较高的能量密度及较好的机械安全性。
在其中一些实施例中，第一电池单元110a的负极活性材料的能量密度小于第二电池单元110b的负极活性材料的能量密度；能量密度较大的负极活性材料通常机械强度一般，而能量密度一般的负极活性材料通常具有较好的机械强度。通过对电池单元110负极活性材料的合理选择设计，内串联电池1兼具较高的能量密度及较好的机械安全性。
可选地，各第一电池单元110a的负极活性材料独立地包括人造石墨、天然石墨、软碳、硬碳及钛酸锂中的至少一种。上述负极材料的理论能量密度一般，而机械强度较好，第一电池单元110a采用上述负极材料，串联模块10两端的电池单元具有较好的机械安全性，不易变形失效。
可选地，各第二电池单元110b的负极活性材料独立地包括硅基材料、锡基材料及锂金属中的至少一种。上述负极材料的理论能量密度较高，而机械强度一般，第二电池单元110b采用上述负极材料，能够保证串联模块10内部的电池单元110具有较高的能量密度，内串联电池1从而具有较高的能量密度。
在其中一些实施例中，第一电池单元110a的正极活性材料的能量密度小于第二电池单元110b的正极活性材料的能量密度；
可选地，各第一电池单元110a的正极活性材料独立地包括LiFe aMn bPO 4、Li 3V 2(PO 4) 3及锰酸锂中的至少一种，其中a+b＝1，0≤a≤1，0≤b≤1；各第二电池单元110b的正极活性材料独立地包括LiNi xCo yMn zO 2及钴酸锂中的至少一种，其中x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1。LiNi xCo yMn zO 2及钴酸锂等正极活性材料的能量密度较高而机械安全性一般，LiFe aMn bPO 4、Li 3V 2(PO 4) 3及锰酸锂等正极活性材料的能量密度较低，但机械安全性较好。通过合理设计第一电池单元110a及第二电池单元110b中正极活性材料的能量密度，内串联电池1兼具较高的能量密度及机械安全性。
可选地，各第一电池单元110a的正极活性材料独立地包括LiNi xCo yMn zO 2，其中x+y+z＝1，0＜x＜0.8，0＜y＜1，0＜z＜1；各第二电池单元110b的正极活性材料独立地包括LiNi xCoyMn zO 2，其中x+y+z＝1，0.8≤x＜1，0＜y＜0.2，0＜z＜0.2。通过第一电池单元110a采用低镍的LiNi xCo yMn zO 2，而第二电池单元110b采用高镍的LiNi xCo yMn zO 2，第一电池单元110a正极活性材料的能量密度小于第二电池单元110b正极活性材料的能量密度。通过合理设计第一电池单元110a及第二电池单元110b中正极活性材料的能量密度，内串联电池1兼具较高的能量密度及机械安全性。
通过合理设计第一电池单元110a及第二电池单元110b中正极活性材料的能量密度，内串联电池1兼具较高的能量密度及机械安全性。
在其中一些实施例中，各第一电池单元110a独立地包括钠离子电池正极活性材料；各第二电池单元110b独立地包括锂离子电池正极材料。锂离子电池体系相对于钠离子电池体系具有较高的能量密度但机械安全性相对较差，通过上述正极活性材料的合理选择设计，内串联电池1兼具较高的能量密度及机械安全性。
在其中一些实施例中，其中，第二电池单元110b的固态电解质层112包括高安全性添加剂。高安全性添加剂能够提升二次电池的循环稳定性及热稳定性，串联模块10内部的温度通常高于两端的温度，通过在第二电池单元110b的固态电解质中添加高安全性添加剂，串联模块内部的电池单元具有较好的循环稳定性及而稳定性，从而降低了内串联电池整体的热失控风险，提升了内串联电池的循环稳定性。
在其中一些实施例中，高安全性添加剂包括磷酸酯及氟代碳酸酯中的至少一种。
在其中一些实施例中，磷酸酯包括磷酸三甲酯及磷酸三乙酯中的至少一种。
在其中一些实施例中，氟代碳酸酯包括二氟乙酸甲酯及二氟乙酸乙酯中的至少一种。
在其中一些实施例中，第一电池单元110a的固态电解质层在25℃的离子电导率＞1×10 -3S/cm；第二电池单元110b的固态电解质层在25℃的离子电导率≤1×10 -3S/cm。通过串联模块内部的温度通常高于两端的温度，导致两端的电池单元的动力学性能通常不及串联模块内部的电池单元的动力学性能。通过合理设计第一电池单元110a、第二电池单元110b的离子电导率，内串联电池整体的内阻较小，具有较好的倍率性能。具体地，固态电解质层的离子电导率可通过以下方法测试：(1)将固态电解质层裁剪为直径19mm的圆片，烘干备用；(2)在惰性气体手套箱中将圆片组装成“标准不锈钢垫片/电解质/标准不锈钢垫片” CR2032扣式实验电池，封装电池压力为5MPa，在25℃下保存1h；(3)使用电化学工作站，按照交流阻抗法(EIS)测量得到对应的Nyquist图谱。环境温度T(单位℃)，测试频率范围为1MHz～100mHz，扰动电压为10mV；(4)测试结束后拆开电池，测量圆片的厚度L(单位cm)，标准垫片的面积S(单位cm 2)，Nyquist图谱拟合得到电阻R(单位Ω)，按照公式
Figure PCTCN2022125328-appb-000001
计算得到固态电解质在T温度时的离子电导率σ(单位S/cm)。
另外，本申请还提供一种用电装置，用电装置包括本申请提供的内串联电池。内串联电池可以用作用电装置的电源，也可以用作用电装置的能量存储单元。用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能***等，但不限于此。
图3是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
实施例中内串联电池按照以下步骤制备：
复合极片制备：在中间集流体不锈钢箔的一侧表面均匀涂布正极浆料，在中间集流体的另一侧表面均匀涂布负极浆料；经过烘干、冷压即得到复合极片，复合极片包括层叠设置的正极活性材料层、中间集流体及负极活性材料层。
单面正极极片制备：在正极集流体铝箔的一侧表面均匀涂布正极浆料；经过烘干、冷压即得到单面正极极片。
单面负极极片制备：在负极集流体铜箔的一侧表面均匀涂布负极浆料；经过烘干、冷压即得到单面负极极片。
固态电解质层制备：将聚合物本体、电解质盐及溶剂在25℃条件下混合均匀，然后烘干、热压，得到固态电解质层。
内串联电池制备：按照单面正极极片、固态电解质层、复合极片、固态电解质层、复合极片、……、复合极片、固态电解质层、单面负极极片的顺序，按照内串联电池设计，将制备好的单面正极极片、固态电解质层、复合极片及单面负极极片叠片，辊压成型，得到电池组件。将电池组件置于包装壳中，经过焊接、封装等工序，制成内串联电池。层叠设置的正极活性材料层、固态电解质层及负极活性材料层组成一个电池单元，内串联电池中有4个电池单元。内串联电池中包括层叠的第一电池单元、第二电池单元、第二电池单元及第一电池单元，即第一电池单元在串联模块的两端，第二电池单元为串联模块内部的电池单元。
测试部分：
能量密度测试：
将内部串联电池以0.33C充电至上限电压，转恒压充电，至充电电流降至0.05C时停止充电，静置30分钟，0.33C放电至下限电压，记录放电能量E(Wh)，放电容量C0(Ah)。对内部串联电池进行称重，记录其重量W(kg)。能量密度＝E/W(Wh/kg)。
热稳定性测试：
热稳定性测试通过热箱测试得到内串联电池发生失效时(起火、***)的温度。具体步骤为：以25℃为初始温度，将内串联电池以5℃/分钟升温至100℃，静置30分钟；之后以5℃/分钟升温并且每5℃保温30分钟，直至内串联电池失效，记录其失效时间，以及内串联电池发生热失效时内部电池单元的温度。
机械安全性测试：
机械安全性测试通过对内串联电池挤压，测试其失效变形量。沿电池单元的层叠方向，用一个半径75mm的半圆柱体对内串联电池的一端施压，挤压速度为2mm/s，持续挤压至内串联电池失效(起火、***)，记录此时半圆柱体的位移，失效变形量(％)＝半圆柱***移/内串联电池沿电池单元的层叠方向的长度。
倍率性能测试：
将内部串联电池以0.33C充电至上限电压，转恒压充电，至充电电流降至0.05C时停止充电，静置30分钟，2C放电至下限电压，记录放电容量C1(Ah)。倍率性能用容量保持率表示，容量保持率＝C1/C0(％)。
对于单一电池单元，分别将其正极活性层及负极活性材料层的表面与集流体贴合，即可得到常规的二次电池。单一电池单元的性能也可以通过上述测试部分的方法测试。
实施例1-1～实施例1-12及对比例1-1～对比例1-5的内串联电池设计参照表1。
在表1中，NCM811正极活性材料层的组成为：质量比97：2：1的NCM811、PVDF及导电剂碳黑。NCM333正极活性材料层的组成为：质量比97：2：1的NCM333、PVDF及导电剂碳黑。LFP正极活性材料层的组成为：质量比97：2：1的LFP、PVDF及导电剂碳黑。NCM811(单晶、多晶质量比为8:2)正极活性材料层的组成为：质量比77.6：19.4：2：1的单晶NCM811、多晶NCM811、PVDF及导电剂碳黑，压实密度为3.3g/cm 3。NCM811(单晶、多晶质量比为2:8)正极活性材料层的组成为：质量比19.4：77.6：2：1的单晶NCM811、多晶NCM811、PVDF及导电剂碳黑，压实密度为3.4g/cm 3。Na 2MnFe(CN) 6正极活性材料层的组成为：质量比97：2：1的Na 2MnFe(CN) 6、PVDF及导电剂碳黑。硅基负极活性材料层的组成为：质量比97：0.5：1.25：1.25的硅基材料、导电剂碳黑、粘结剂丁苯橡胶(SBR)、增稠剂羟甲基纤维素钠(CMC-Na)。石墨负极活性材料层的组成为：质量比97：0.5：1.25：1.25的石墨、导电剂碳黑、粘结剂丁苯橡胶(SBR)、增稠剂羟甲基纤维素钠(CMC-Na)。硬碳负极活性材料层的组成为：质量比97：0.5：1.25：1.25的硬碳、导电剂碳黑、粘结剂丁苯橡胶(SBR)、增稠剂羟甲基纤维素钠(CMC-Na)。PEO-LiTFSI固态电解质层的组成为：质量比25：75的PEO及LiTFSI。Na-β-Al 2O 3固态电解质层的组成为：质量百分比100％的Na-β-Al 2O 3。
表1
Figure PCTCN2022125328-appb-000002
Figure PCTCN2022125328-appb-000003
Figure PCTCN2022125328-appb-000004
从表1相关数据可以看出，实施例1-1～1-12通过调整第一电池单元、第二电池单元的组成，实施例1-1～1-12的内串联电池的能量密度为280Wh/kg～370Wh/kg，内串联电池失效时的内部温度为130℃～190℃，内串联电池兼具较高的能量密度及较好的热稳定性。对比例1-1～1-5的内串联电池中第一电池单元、第二电池单元的组成相同，得到的内串联电池难以兼顾较高的能量密度及较好的热稳定性。
实施例2-1～实施例2-9的内串联电池设计参照表2。
在表2中，NCM811正极活性材料层的组成为：质量比97：2：1的NCM811、PVDF及导电剂碳黑。NCM333正极活性材料层的组成为：质量比97：2：1的NCM333、PVDF及导电剂碳黑。LFP正极活性材料层的组成为：质量比97：2：1的LFP、PVDF及导电剂碳黑。Na 2MnFe(CN) 6正极活性材料层的组成为：质量比97：2：1的Na 2MnFe(CN) 6、PVDF及导电剂碳黑。硅基负极活性材料层的组成为：质量比97：0.5：1.25：1.25的硅基材料、导电剂碳黑、粘结剂丁苯橡胶(SBR)、增稠剂羟甲基纤维素钠(CMC-Na)。石墨负极活性材料层的组成为：质量比97：0.5：1.25：1.25的石墨、导电剂碳黑、粘结剂丁苯橡胶(SBR)、增稠剂羟甲基纤维素钠(CMC-Na)。硬碳负极活性材料层的组成为：质量比97：0.5：1.25：1.25的硬碳、导电剂碳黑、粘结剂丁苯橡胶(SBR)、增稠剂羟甲基纤维素钠(CMC-Na)。PEO-LiTFSI固态电解质层的组成为：质量比25：75的PEO、LiTFSI。Na-β-Al 2O 3固态电解质层的组成为：质量百分比100％的Na-β-Al 2O 3。
表2
Figure PCTCN2022125328-appb-000005
Figure PCTCN2022125328-appb-000006
Figure PCTCN2022125328-appb-000007
从表2相关数据可以看出，实施例2-1～2-10通过调整第一电池单元、第二电池单元的组成，实施例2-1～2-10的内串联电池的能量密度为262Wh/kg～368Wh/kg，失效变形量为23％～40％，内串联电池兼具较高的能量密度及较好的机械安全性。相对于对比例1-1～1-5，实施例2-1～实施例2-10的内串联电池综合性能更佳。
实施例3-1～实施例3-4的内串联电池与实施例1-1的区别在于，固态电解质层的组成、离子电导率不同。实施例3-1～实施例3-4的内串联电池设计参照表3。在实施例3-1～实施例3-4中，电导率为1mS/cm的PEO-LiTFSI固态电解质层的组成为：质量比25：75的PEO、LiTFSI。电导率为3mS/cm的PEO-LiTFSI固态电解质层的组成为：质量比20:20:60的增塑剂EC、PEO、LiTFSI。
表3
Figure PCTCN2022125328-appb-000008
从表3相关数据，由实施例3-2可以看出，固态电解质层的离子电导率对内串联电池的能量密度、倍率性能、热稳定性均有影响。固态电解质层的离子电导率较大，内串联电池的能量密度及倍率性能较佳，但内串联电池的热稳定性下降。从实施例3-2～3-4对比可以看出，高安全性添加剂能够改善内串联电池的 热稳定性。实施例3-1的内串联电池中，第一电池单元的固态电解质层的离子电导率为3mS/cm，未添加高安全添加剂，第二电池单元的固态电解质层的离子电导率为1mS/cm，添加二氟乙酸乙酯，制得的内串联电池的能量密度为345Wh/kg，倍率性能为83％，内串联电池失效时内部温度为200℃。相对于实施例3-2～3-4的内串联电池，实施例3-1内串联电池的综合性能更佳。
以上所述实施例的各技术特征可以进行任意的组合，为使描述简洁，未对上述实施例中的各个技术特征所有可能的组合都进行描述，然而，只要这些技术特征的组合不存在矛盾，都应当认为是本说明书记载的范围。
以上所述实施例仅表达了本申请的几种实施方式，其描述较为具体和详细，但并不能因此而理解为对发明专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本申请构思的前提下，还可以做出若干变形和改进，这些都属于本申请的保护范围。因此，本申请专利的保护范围应以所附权利要求为准。

Claims (14)

  1. 一种内串联电池，包括：
    串联模块，包括电池单元及中间集流体；所述电池单元的数量≥3，各所述电池单元包括层叠设置的正极活性材料层、固态电解质层及负极活性材料层；所述中间集流体设置于相邻的两个所述电池单元之间，且相邻的两个所述电池单元以所述中间集流体串联；
    正极集流体，位于所述串联模块的一端且与该端部的电池单元的正极活性材料层电连接；以及
    负极集流体，位于所述串联模块的另一端且与该端部的电池单元的负极活性材料层电连接；
    其中，所述电池单元包括第一电池单元及第二电池单元；所述第一电池单元的能量密度与位于所述串联模块两端的任一电池单元的能量密度相同；所述第二电池单元的能量密度与位于所述串联模块两端的电池单元的能量密度不同。
  2. 根据权利要求1所述的内串联电池，其中，所述第二电池单元的数量与所述电池单元总数量的比值为(1～2)：3。
  3. 根据权利要求1或2所述的内串联电池，其中，所述第一电池单元的能量密度大于所述第二电池单元的能量密度。
  4. 根据权利要求1～3任一项所述的内串联电池，其中，所述第一电池单元的负极活性材料的能量密度大于所述第二电池单元的负极活性材料的能量密度；
    可选地，各所述第一电池单元的负极活性材料独立地包括硅基材料、锡基材料及锂金属中的至少一种；
    可选地，各所述第二电池单元的负极活性材料独立地包括人造石墨、天然石墨、软碳、硬碳及钛酸锂中的至少一种。
  5. 根据权利要求1～4任一项所述的内串联电池，其中，所述第一电池单元的正极活性材料的能量密度大于所述第二电池单元的正极活性材料的能量密度；
    可选地，各所述第一电池单元的正极活性材料独立地包括LiNi xCoyMn zO 2及钴酸锂中的至少一种，其中x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1；各所述第二电池单元的正极活性材料独立地包括LiFe aMn bPO 4、Li 3V 2(PO 4) 3及锰酸锂中的至少一种，其中a+b＝1，0≤a≤1，0≤b≤1；
    可选地，各所述第一电池单元的正极活性材料独立地包括LiNi xCoyMn zO 2，其中x+y+z＝1，0.8≤x＜1，0＜y＜0.2，0＜z＜0.2；各所述第二电池单元的正极活性材料独立地包括LiNi xCoyMn zO 2，其中x+y+z＝1，0＜x＜0.8，0＜y＜1，0＜z＜1。
  6. 根据权利要求3所述的内串联电池，其中，各所述第一电池单元独立地包括锂离子电池正极活性材料；各所述第二电池单元独立地包括钠离子电池正极材料。
  7. 根据权利要求1或2所述的内串联电池，其中，各所述第一电池单元及各所述第二电池单元的正极活性材料独立地包括LiNi xCo yMn zO 2，其中x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1；所述第一电池单元的正极活性材料层的压实密度小于所述第二电池单元的正极活性材料层的压实密度。
  8. 根据权利要求1或2所述的内串联电池，其中，所述第一电池单元的能量密度小于所述第二电池单元的能量密度。
  9. 根据权利要求1～2、8任一项所述的内串联电池，其中，所述第一电池单元的负极活性材料的能量密度小于所述第二电池单元的负极活性材料的能量密度；
    可选地，各所述第一电池单元的负极活性材料独立地包括人造石墨、天然石墨、软碳、硬碳及钛酸锂中的至少一种；
    可选地，各所述第二电池单元的负极活性材料独立地包括硅基材料、锡基材料及锂金属中的至少一种。
  10. 根据权利要求1～2、8～9任一项所述的内串联电池，其中，所述第一电池单元的正极活性材料的能量密度小于所述第二电池单元的正极活性材料的能量密度；
    可选地，各所述第一电池单元的正极活性材料独立地包括LiFe aMn bPO 4、Li 3V 2(PO 4) 3及锰酸锂中的至少一种，其中a+b＝1，0≤a≤1，0≤b≤1；各所述第二电池单元的正极活性材料独立地包括LiNi xCo yMn zO 2及钴酸锂中的至少一种，其中x+y+z＝1，0＜x＜1，0＜y＜1，0＜z＜1；
    可选地，各所述第一电池单元的正极活性材料独立地包括LiNi xCo yMn zO 2，其中x+y+z＝1，0＜x＜0.8，0＜y＜1，0＜z＜1；各所述第二电池单元的正极活性材料独立地包括LiNi xCo yMn zO 2，其中x+y+z＝1，0.8≤x＜1，0＜y＜0.2，0＜z＜0.2。
  11. 根据权利要求8所述的内串联电池，其中，各所述第一电池单元独立地包括钠离子电池正极活性材料；各所述第二电池单元独立地包括锂离子电池正极材料。
  12. 根据权利要求1～11任一项所述的内串联电池，其中，所述第二电池单元的固态电解质层包括高安全性添加剂；
    可选地，所述高安全性添加剂包括磷酸酯及氟代碳酸酯中的至少一种；
    可选地，所述磷酸酯包括磷酸三甲酯及磷酸三乙酯中的至少一种；
    可选地，所述氟代碳酸酯包括二氟乙酸甲酯及二氟乙酸乙酯中的至少一种。
  13. 根据权利要求1～12任一项所述的内串联电池，其中，所述第一电池单元的固态电解质在25℃的离子电导率＞1×10 -3S/cm；所述第二电池单元的固态电解质在25℃的离子电导率≤1×10 -3S/cm。
  14. 一种用电装置，包括权利要求1～13任一项所述的内串联电池。
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