WO2023050972A1 - 电池单体、电池和用电装置 - Google Patents

电池单体、电池和用电装置 Download PDF

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Publication number
WO2023050972A1
WO2023050972A1 PCT/CN2022/105159 CN2022105159W WO2023050972A1 WO 2023050972 A1 WO2023050972 A1 WO 2023050972A1 CN 2022105159 W CN2022105159 W CN 2022105159W WO 2023050972 A1 WO2023050972 A1 WO 2023050972A1
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Prior art keywords
electrode assembly
pole piece
separator
battery
battery cell
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PCT/CN2022/105159
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English (en)
French (fr)
Inventor
陈思谣
杜鑫鑫
上官会会
杨道伟
白子瑜
Original Assignee
宁德时代新能源科技股份有限公司
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Publication of WO2023050972A1 publication Critical patent/WO2023050972A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/204—Racks, modules or packs for multiple batteries or multiple cells
    • H01M50/207—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape
    • H01M50/209—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape adapted for prismatic or rectangular cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M6/00—Primary cells; Manufacture thereof
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of batteries, in particular to a battery cell, a battery and an electrical device thereof.
  • Batteries are widely used in electronic equipment, such as mobile phones, laptop computers, battery cars, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools, etc. Batteries can include nickel-cadmium batteries, nickel-hydrogen batteries, lithium-ion batteries, and secondary alkaline zinc-manganese batteries, among others.
  • the length of battery life is related to its convenience.
  • the battery life is short, it is easy to cause frequent battery replacement during battery use, which will cause inconvenience during use and affect its economy. benefit play.
  • the present application provides a battery cell, a battery and an electric device, which can prolong the service life of the battery.
  • the present application provides a battery cell, which includes:
  • first electrode assembly and a second electrode assembly stacked vertically, the first electrode assembly is arranged below the second electrode assembly,
  • the first electrode assembly includes a first separator
  • the second electrode assembly includes a second separator
  • the air permeability of the second separator is greater than that of the first separator
  • the second electrode assembly stacked above has a smaller contact area with the electrolyte, and under the heat conduction of the electrolyte, the temperature rise capability of the second electrode assembly is higher than that of the first electrode
  • the temperature rise capability of the components makes it easy for the second electrode component to continue to work in a high temperature state, thereby shortening the service life.
  • the ability of the second separator to store electrolyte is improved, which can reduce the probability of the second electrode assembly continuing to work at high temperature, prolong the service life of the battery as a whole, and thus improve the convenience of the battery during use.
  • the porosity of the second spacer is greater than the porosity of the first spacer.
  • Porosity refers to the ratio of the pore area of the spacer per unit area.
  • both the first electrode assembly and the second electrode assembly are wound electrode assemblies, and along the winding direction, the length of the second separator is greater than that of the first separator.
  • the porosity is constant, the larger the area of the separator, the larger the number and total area of the pores.
  • the total area of the pores on the second separator can be made larger than the total area of the pores on the first separator, so that the electrolyte storage capacity of the second separator is higher than that of the first separator.
  • the number of winding turns of the second separator is greater than that of the first separator.
  • the total length of the second separator will be greater than the total length of the first separator, which can make the capacity of the second separator to store electrolyte higher than that of the first separator.
  • the capacity of the first separator to store electrolyte can be higher than that of the first separator.
  • the gap between the layers can absorb and store a certain amount of electrolyte by using the capillary effect. Therefore, the number of winding turns of the second separator is greater than that of the first separator. The number of winding turns can form a plurality of gaps in the second electrode assembly to store the electrolyte.
  • the first electrode assembly further includes a first pole piece
  • the second electrode assembly further includes a second pole piece
  • the first pole piece and the second pole piece have the same polarity, and the compaction density of the first pole piece is greater than The compacted density of the second pole piece.
  • the degree of extrusion between the material particles is too large, so that the compaction density of the pole piece is higher and the porosity is smaller, and the absorption of the electrolyte will also be reduced.
  • the compaction density of the first pole piece is greater than that of the second pole piece, so that the porosity of the second pole piece is greater than that of the first pole piece, so as to improve the electrolysis of the second pole piece. Liquid absorption capacity.
  • both the first pole piece and the second pole piece are positive pole pieces
  • the compacted density of the first pole piece is 3.2g/cm 3 -3.5g/cm 3
  • the compacted density of the second pole piece is 3.0g/cm 3 -3.25g/cm 3 ;
  • the first pole piece and the second pole piece are only negative pole pieces, the compacted density of the first pole piece is 1.55g/cm 3 -1.7 g/cm 3 , and the compacted density of the second pole piece is 1.4g/cm 3 - 1.55g/cm 3 .
  • the compacted density of the pole piece can be set in a more appropriate range to avoid affecting the capacity of the battery.
  • the compacted density of the first pole piece and the second pole piece can be adjusted. On the basis that the two are still within a reasonable range, the compacted density of the first pole piece is greater than that of the second pole piece, so that the ability of the second pole piece to absorb the electrolyte is higher.
  • the first electrode assembly further includes a first groove
  • the second electrode assembly further includes a second groove
  • both the first groove and the second groove are used to store at least part of the electrolyte
  • the second groove The volume of the groove is greater than the volume of the first groove.
  • both the first groove on the first electrode assembly and the second groove on the second electrode assembly can absorb and store a certain amount of electrolyte, which can increase the migration speed of lithium ions and improve the efficiency of the electric cycle. performance; moreover, the groove structure on the second electrode assembly can be made more capable of absorbing and storing electrolyte, and can absorb and store more electrolyte.
  • an embodiment of the present application provides a battery, which includes: the battery cell according to any embodiment of the first aspect.
  • an embodiment of the present application provides an electrical device, including the battery in the second aspect, and the battery is used to provide electrical energy.
  • Fig. 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.
  • Fig. 2 is a schematic explosion diagram of a battery provided by some embodiments of the present application.
  • Fig. 3 is a schematic explosion diagram of a battery cell provided by some embodiments of the present application.
  • Fig. 4 is the sectional view of A-A direction in Fig. 3;
  • Fig. 5 is a schematic structural diagram of a first electrode assembly and a second electrode assembly provided by some embodiments of the present application;
  • Figure 6 is a schematic structural view of a first electrode assembly and a second electrode assembly provided by other embodiments of the present application.
  • Fig. 7 is a schematic diagram of the expansion of the first pole piece and the second pole piece provided by some embodiments of the present application.
  • 11-box body 111-first box body part, 112-second box body part, 113-accommodating space;
  • 100-Battery cell 110-Case, 120-End cap, 130-First electrode assembly, 131-First separator, 133-First groove, 140-Second electrode assembly, 141-Second separator , 143-the second groove;
  • connection In the description of this application, it should be noted that, unless otherwise clearly stipulated and limited, the terms “installation”, “connection”, “connection” and “attachment” should be understood in a broad sense, for example, it may be a fixed connection, It can also be detachably connected or integrally connected; it can be directly connected or indirectly connected through an intermediary, and it can be internal communication between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application according to specific situations.
  • “Plurality” in this application refers to two or more (including two).
  • the battery cells may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells, or magnesium-ion battery cells, etc.
  • the embodiment of the present application does not limit this.
  • the battery cell can be in the form of a cylinder, a flat body, a cuboid or other shapes, which is not limited in this embodiment of the present application.
  • Battery cells are generally divided into three types according to packaging methods: cylindrical battery cells, square battery cells and pouch battery cells, which are not limited in this embodiment of the present application.
  • the battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.
  • the battery mentioned in this application may include a battery module or a battery pack, and the like.
  • Batteries generally include a case for enclosing one or more battery cells. The box can prevent liquid or other foreign objects from affecting the charging or discharging of the battery cells.
  • the battery cell includes a casing, an end cap, an electrode assembly and an electrolyte.
  • the end cap and the casing are sealed to form an accommodating space, and the electrode assembly and the electrolyte are placed in the accommodating space.
  • the electrode assembly includes a positive pole piece, a negative pole piece and a separator.
  • a battery cell works primarily by moving metal ions between the positive and negative pole pieces.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer is coated on the surface of the positive electrode current collector;
  • the positive electrode current collector includes a positive electrode current collector and a positive electrode protrusion protruding from the positive electrode current collector, and the positive electrode current collector part is coated with a positive electrode active material layer, at least part of the positive electrode convex part is not coated with a positive electrode active material layer, and the positive electrode convex part is used as a positive electrode tab.
  • the material of the positive electrode current collector can be aluminum, the positive electrode active material layer includes the positive electrode active material, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium or lithium manganate.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is coated on the surface of the negative electrode current collector; the negative electrode current collector includes a negative electrode current collector and a negative electrode protrusion protruding from the negative electrode current collector. part is coated with a negative electrode active material layer, at least part of the negative electrode convex part is not coated with a negative electrode active material layer, and the negative electrode convex part is used as a negative electrode tab.
  • the material of the negative electrode current collector may be copper, the negative electrode active material layer includes the negative electrode active material, and the negative electrode active material may be carbon or silicon.
  • the number of positive pole tabs is multiple and stacked together, and the number of negative pole tabs is multiple and stacked together.
  • the material of the spacer can be PP (polypropylene, polypropylene) or PE (polyethylene, polyethylene).
  • the electrode assembly may be a wound structure or a laminated structure, which is not limited in the embodiment of the present application.
  • the cycle performance and service life of the battery cell as a whole are related to multiple indicators of each electrode assembly in the case during use.
  • the above situation is due to the fact that the contact area between the electrode assembly stacked above and the electrolyte is too small, which makes it difficult for the heat generated when the electrode assembly undergoes a chemical reaction to be conducted to other places through the electrolyte, resulting in heat generation. If the rate is greater than the rate of heat dissipation, the temperature of the electrode assembly will continue to rise, and the increase in temperature will cause the electrode assembly to lose water at a faster rate, further aggravating the temperature rise. When the temperature of the electrode assembly is too high, it will destroy the internal chemical balance, cause side reactions, and degrade the performance of chemical materials, thereby shortening the cycle life of the electrode assembly and the battery cell as a whole.
  • an embodiment of the present application provides a battery cell, the battery cell includes a first electrode assembly and a second electrode assembly, the first electrode assembly includes a first separator, and the second electrode assembly includes a second electrode assembly.
  • the air permeability of the second separator is greater than that of the first separator.
  • the battery cells described in the embodiments of the present application are applicable to batteries and electric devices using batteries.
  • Electric devices can be vehicles, mobile phones, portable devices, notebook computers, ships, spacecraft, electric toys and electric tools, and so on.
  • Vehicles can be fuel vehicles, gas vehicles or new energy vehicles, and new energy vehicles can be pure electric vehicles, hybrid vehicles or extended-range vehicles;
  • spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.;
  • electric toys include fixed Type or mobile electric toys, such as game consoles, electric car toys, electric boat toys and electric airplane toys, etc.;
  • electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, for example, Electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, electric planers, and more.
  • the embodiments of the present application do not impose special limitations on the above-mentioned electrical devices.
  • the electric device is taken as an example for description.
  • Fig. 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.
  • a battery 10 is arranged inside the vehicle 1 , and the battery 10 may be arranged at the bottom, head or tail of the vehicle 1 .
  • the battery 10 can be used for power supply of the vehicle 1 , for example, the battery 10 can be used as an operating power source of the vehicle 1 .
  • the vehicle 1 may further include a controller 20 and a motor 30 , the controller 20 is used to control the battery 10 to supply power to the motor 30 , for example, to meet the power requirements for starting, navigating and driving of the vehicle 1 .
  • the battery 10 can not only be used as an operating power source for the vehicle 1 , but can also be used as a driving power source for the vehicle 1 to provide driving power for the vehicle 1 instead of or partially replacing fuel oil or natural gas.
  • FIG. 2 is a schematic exploded view of the battery 10 provided by some embodiments of the present application.
  • the battery 10 includes a case body 11 and a battery cell 100 , and the battery cell 100 is accommodated in the case body 11 .
  • the box body 11 is used for accommodating the battery cells 100, and the box body 11 may have various structures.
  • the box body 11 may include a first box body part 111 and a second box body part 112, the first box body part 111 and the second box body part 112 cover each other, the first box body part 111 and the second box body part 112
  • the two box parts 112 jointly define an accommodating space 113 for accommodating the battery cells.
  • the second box part 112 can be a hollow structure with one end open, the first box part 111 is a plate-shaped structure, and the first box part 111 covers the opening side of the second box part 112 to form an accommodating space 113
  • the box body 11; the first box body part 111 and the second box body part 112 also can be the hollow structure of one side opening, and the opening side of the first box body part 111 covers the opening side of the second box body part 112 , to form a box body 11 with a receiving space 113 .
  • the first box body part 111 and the second box body part 112 may be in various shapes, such as a cylinder, a cuboid, and the like.
  • a sealing member may also be provided between the first box part 111 and the second box part 112, such as sealant, sealing ring, etc. .
  • the first box part 111 covers the top of the second box part 112
  • the first box part 111 can also be called an upper box cover
  • the second box part 112 can also be called a lower box.
  • the plurality of battery cells 100 may be connected in series, in parallel or in parallel.
  • the mixed connection means that the plurality of battery cells 100 are both in series and in parallel.
  • a plurality of battery cells 100 can be directly connected in series, in parallel or mixed together, and then the whole composed of a plurality of battery cells 100 is housed in the box 11; of course, a plurality of battery cells 100 can also be connected in series first Either in parallel or in parallel to form a battery module (not shown in the figure), and a plurality of battery modules are connected in series or in parallel or in series to form a whole and accommodated in the box 11 .
  • the multiple battery cells 100 in the battery module can be electrically connected through a bus component, so as to realize the parallel connection, series connection or mixed connection of the multiple battery cells 100 in the battery module.
  • FIG. 3 is an exploded schematic diagram of a battery cell 100 provided in some embodiments of the present application.
  • the present application provides a battery cell 100, which includes a first electrode assembly 130 and a second electrode assembly 140 stacked along a vertical direction X, wherein the first electrode assembly 130 is set Below the second electrode assembly 140, the first electrode assembly 130 includes a first separator 131, the second electrode assembly 140 includes a second separator 141, and the air permeability of the second separator 141 is greater than that of the first separator 131. .
  • the electrode assembly in the embodiment of the present application may be a wound electrode assembly or a laminated electrode assembly, which is not limited in this application.
  • the following contents and drawings all take a wound electrode assembly as an example.
  • the first electrode assembly 130 and the second electrode assembly 140 are stacked along the vertical direction X, that is, the first electrode assembly 130 and the second electrode assembly 140 are placed side by side along the thickness direction, because the electrolyte in the casing 110 is usually not full In the remaining space in the housing 110 , under the action of gravity, more electrolyte is stored in the lower part of the housing 110 .
  • the first electrode assembly 130 stacked below it is easy to cause the first electrode assembly 130 stacked below to have a larger contact area with the electrolyte, and during use, the first electrode assembly 130 can continuously maintain a larger area of contact with the electrolyte, therefore,
  • the heat generated by the first electrode assembly 130 in the circulation process can be dissipated through the electrolyte without accumulating heat; the second electrode assembly 140 is difficult to contact the electrolyte or has only a small area of contact with the electrolyte during use, and the heat It is difficult to disperse, and it is easy to be in a high-temperature state for a long time, so the second electrode assembly 140 is prone to the problem of life-span deterioration.
  • the first electrode assembly 130 generally includes two separators, and the first separator 131 may be any one of the two separators.
  • the second electrode assembly 140 generally also includes two separators, and the second separator 141 may be any one of the two separators.
  • the air permeability of the second spacer 141 is greater than the air permeability of the first spacer 131. It should be noted here that the air permeability refers to the air permeability of the first spacer 131 or the second spacer 141 as a whole. Specifically, it can be tested The time required for the same volume of the same gas to completely pass through the first spacer 131 and the second spacer 141 respectively, the air permeability of the second spacer 141 is greater than that of the first spacer 131, that is, the gas completely passes through the second spacer 141 The time for passing through the first spacer 131 is shorter than the time for completely passing through the first spacer 131 .
  • the air permeability of the first spacer 131 or the second spacer 141 is related to the total area of the pores distributed thereon, the larger the total area of the pores, the more air passes through at the same time. The more gas volume, the higher the air permeability.
  • the second electrode assembly 140 can retain more electrolyte in the second separator by virtue of the adsorption capacity of the liquid when in contact with the electrolyte. 141, so that the ability of the second electrode assembly 140 to store the electrolyte is higher than the ability of the first electrode assembly 130 to store the electrolyte. In this way, the deterioration of the life of the second electrode assembly 140 can be improved, so that the battery cell 100 as a whole Cycle life is extended.
  • FIG. 4 is a cross-sectional view along A-A in FIG. 3 .
  • the porosity of the second spacer 141 is greater than that of the first spacer 131 .
  • the porosity refers to the proportion of the total area of pores on the first spacer 131 or the second spacer 141 per unit area.
  • the number of pores is set to be large, or the area of a single pore is set to be large, which will help to increase the porosity. . Therefore, more pores than the first spacer 131 can be set on the second spacer 141, and the size of a single hole on the second spacer 141 can also be set larger than the size of the first spacer 131, so as to The porosity of the second spacer 141 is made larger than the porosity of the first spacer 131 .
  • the ability of the second separator 141 to store electrolyte is stronger than that of the first separator 131 to store electrolyte.
  • the second separator 141 can retain more electrolyte in the pores by short-term contact with the electrolyte, so as to improve the deterioration of the life of the second electrode assembly 141. Phenomenon.
  • FIG. 5 is a schematic structural diagram of the first electrode assembly 131 and the second electrode assembly 141 provided by some embodiments of the present application.
  • both the first electrode assembly 131 and the second electrode assembly 141 are wound electrode assemblies, and along the winding direction, the length L 1 of the second separator 141 is greater than the length L 2 of the first separator 131 .
  • the porosity per unit area of the first spacer 131 and the second spacer 141 is constant, by extending the length L 2 of the second spacer 141, the total pore area of the second spacer 141 can be increased, so that the second spacer
  • the length L2 of the piece 141 is greater than the length of the first spacer L1 , so that the total pore area of the second spacer 141 can be greater than the total area of the pores of the first spacer 131, so that the second spacer 141 can store more in the pores.
  • a large amount of electrolyte is used to balance the temperature rise capability of the battery cell 100 as a whole, delay the deterioration of the service life of the second electrode assembly 141 , and finally prolong the service life of the battery cell 100 as a whole.
  • FIG. 6 is a schematic structural diagram of the first electrode assembly 131 and the second electrode assembly 141 provided in other embodiments of the present application.
  • the number of winding turns N 1 of the second separator 141 is greater than the number of winding turns N 2 of the first separator 131 .
  • Winding one circle refers to starting from a certain straight line parallel to the width direction on the separator, extending along the winding direction of the electrode assembly to another straight line parallel to the width direction on the separator, and the plane formed by connecting the two straight lines can be Passing through the center of the electrode assembly, the separator distributed between the two straight lines is the separator wound in one circle.
  • a long and narrow gap can be formed between the separators of adjacent rings, and the gap can absorb and retain a certain amount of electrolyte under capillary action. more space.
  • the number N1 of winding turns of the second spacer 141 is greater than the number N2 of winding turns of the first spacer 131, so that the second spacer 141 can form a gap with a larger size along the winding direction. In this way, the second spacer The gap 141 can use the gap to retain more electrolyte to delay the deterioration of the life of the second separator 141 , so that the life of the second separator 141 can be extended to balance the service life of the battery cell 100 as a whole.
  • the first electrode assembly 131 further includes a first pole piece
  • the second electrode assembly 141 further includes a second pole piece
  • the first pole piece and the second pole piece have the same polarity
  • the compacted density of the first pole piece is greater than the compacted density of the second pole piece.
  • the compaction density of the pole piece refers to the ratio of the volume of the active material to the total volume.
  • the compaction density of the pole piece is used to characterize the degree of filling of the volume of the pole piece by the active material, which reflects the compactness of the distribution of the active material.
  • the compaction density of the pole piece will affect the porosity of the pole piece, thereby affecting the absorption of the electrolyte by the pole piece. The lower the absorption capacity.
  • the compaction density requirements for the positive electrode sheet and the negative electrode sheet are also different.
  • the compacted density of the first pole piece is greater than that of the second pole piece, so that the porosity of the second pole piece can be greater than that of the first pole piece.
  • the porosity of the first pole piece ultimately makes the absorption of the electrolyte by the second pole piece greater than that of the first pole piece, so as to delay the deterioration of the life of the second pole piece.
  • the compacted density of the first pole piece when both the first pole piece and the second pole piece are positive pole pieces, the compacted density of the first pole piece may be 3.2g/cm 3 -3.5g/cm 3 ,
  • the compacted density of the second pole piece can be 3.0g/cm 3 -3.25g/cm 3 , or, when the first pole piece and the second pole piece are negative pole pieces, the compacted density of the first pole piece can be 1.55 g/cm 3 -1.7g/cm 3 , the compacted density of the second pole piece may be 1.4g/cm 3 -1.55g/cm 3 .
  • FIG. 7 is a schematic diagram of the expansion of the first pole piece and the second pole piece provided by some embodiments of the present application.
  • the first electrode assembly 130 further includes a first groove 133
  • the second electrode assembly 140 further includes a second groove 143
  • the tanks 143 are used to store at least part of the electrolyte, and the volume of the second groove 143 is greater than that of the first groove 133 .
  • the first electrode assembly 130 can be provided with a first groove 133, and the first groove 133 can be arranged on the positive electrode sheet or the negative electrode sheet of the first electrode assembly 130, and the first groove 133 can be used to coat the active material on the positive electrode sheet or the negative electrode sheet
  • the thickness of the area is smaller, and the coating thickness of this area is smaller than that of other areas, so that this area is in the form of a depression on the surface of the pole piece, or this area can also be a current collector that is not coated with an active material and exposed.
  • the second electrode assembly 140 can be provided with a second groove 143, and the second groove 143 can be arranged on the positive electrode sheet or the negative electrode sheet of the second electrode assembly 140, and the second groove 143 can be used to coat the active material on the positive electrode sheet or the negative electrode sheet
  • the thickness of the area is smaller, and the coating thickness of this area is smaller than that of other areas, so that this area is in the form of a depression on the surface of the pole piece, or this area can also be a current collector that is not coated with an active material and exposed.
  • the first electrode assembly 130 or the second electrode assembly 140 contacts the electrolyte, a part of the electrolyte can be retained in the first groove 133 or the second groove 143 by virtue of the adsorption force of the electrolyte.
  • the second groove 143 can store more electrolyte than the first groove 133 when contacting the electrolyte, like this, the second electrode assembly 140 reacts Part of the generated heat can be conducted and diffused through the electrolyte, so as to reduce the operating temperature of the second electrode assembly 140 and alleviate the deterioration of the life of the second electrode assembly 140 .

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Abstract

本申请公开了一种电池单体，该电池单体包括沿竖直方向堆叠的第一电极组件和第二电极组件，其中，第一电极组件包括第一隔离件，第二电极组件包括第二隔离件，第二隔离件的透气度大于第一隔离件的透气度，使得第二电极组件能够在与电解液接触时留存较多的电解液，该部分电解液有利于传导散开第二电极组件上产生的局部热量，避免第二电极组件发生局部干烧或持续高温使用，从而延长第二电极组件和电池单体整体的使用寿命。

Description

电池单体、电池和用电装置
相关申请的交叉引用
本申请要求享有于2021年9月28日提交的名称为“电池单体、电池和用电装置”的中国专利申请202122363005.9的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请涉及电池领域，特别是涉及一种电池单体、电池及其用电装置。
背景技术
电池广泛用于电子设备，例如手机、笔记本电脑、电瓶车、电动汽车、电动飞机、电动轮船、电动玩具汽车、电动玩具轮船、电动玩具飞机和电动工具等等。电池可以包括镉镍电池、氢镍电池、锂离子电池和二次碱性锌锰电池等。
在电池技术的发展中，电池使用寿命的长短关系到其便捷性，当电池的寿命较短时，容易造成在电池的使用过程中需频繁更换电池，从而造成使用过程中的不便，影响其经济效益的发挥。
发明内容
本申请提供一种电池单体、电池和用电装置，其能延长电池的使用寿命。
第一方面，本申请提供一种电池单体，其包括：
沿竖直方向堆叠的第一电极组件和第二电极组件，第一电极组件设置于第二电极组件的下方，
第一电极组件包括第一隔离件，第二电极组件包括第二隔离件，第二隔离件的透气度大于第一隔离件的透气度。
相比于堆叠于下方的第一电极组件，堆叠于上方的第二电极组件与电解液的接触面积较小，在电解液的热传导作用下，第二电极组件的温升能力高于第一电极组件的温升能力，导致第二电极组件容易在高温状态下持续工作从而使寿命缩短。通过采用上述方案，使得第二隔离件存储电解液的能力提升，可以降低第二电极组件持续高温工作的概率，延长电池单体整体的使用寿命，从而 提高电池在使用过程中的便捷性。
在一些实施例中，第二隔离件的孔隙率大于第一隔离件的孔隙率。
孔隙率是指单位面积的隔离件上孔隙面积的占比，通过采用上述方案，使第二隔离件的孔隙率大于第一隔离件的孔隙率，这样，第二隔离件上可以有更大的孔隙面积用于存储部分的电解液，可以有效提升第二隔离件的电解液存储能力。
在一些实施例中，第一电极组件和第二电极组件均为卷绕式的电极组件，沿卷绕方向，第二隔离件的长度大于第一隔离件的长度。
当孔隙率一定时，隔离件的面积越大，孔隙的数量和总面积也就越大。通过采用上述方案，可以使得第二隔离件上的孔隙总面积大于第一隔离件上的孔隙总面积，从而使第二隔离件的电解液存储能力高于第一隔离件的电解液存储能力。
在一些实施例中，沿卷绕方向，第二隔离件的卷绕圈数大于第一隔离件的卷绕圈数。
通过采用上述方案，当第一电极组件和第二电极组件的尺寸相同时，第二隔离件的总长度会大于第一隔离件的总长度，可以使得第二隔离件存储电解液的能力高于第一隔离件存储电解液的能力。并且，在隔离件卷绕形成的多层结构中，层与层间的间隙可以利用毛细效应吸取并存储一定的电解液，因此，使第二隔离件的卷绕圈数大于第一隔离件的卷绕圈数，可以使第二电极组件中形成多个上述间隙用以存储电解液。
在一些实施例中，第一电极组件还包括第一极片，第二电极组件还包括第二极片，第一极片和第二极片极性相同，第一极片的压实密度大于第二极片的压实密度。
过压的极片中，材料颗粒之间的挤压程度过大，使得极片的压实密度较大而孔隙率较小，对电解液的吸收量也会降低。通过采用上述方案，使第一极片的压实密度大于第二极片的压实密度，从而使第二极片的孔隙率大于第一极片的孔隙率，以提高第二极片对电解液的吸收能力。
在一些实施例中，第一极片和第二极片均为正极片，第一极片的压实密度为3.2g/cm 3-3.5g/cm 3，第二极片的压实密度为3.0g/cm 3-3.25g/cm 3；或者，
第一极片和第二极片仅为负极片，第一极片的压实密度为1.55g/cm 3-1.7 g/cm 3，第二极片的压实密度为1.4g/cm 3-1.55g/cm 3。
在一定范围内，极片的压实密度越大，电池的容量越高，但是，当极片过压时，又容易造成锂离子嵌入困难，从而导致电池的容量降低、循环恶化和内阻增加的问题。因此，通过采用上述方案，可以将极片的压实密度设定在较为合适的范围内，避免影响电池的容量，同时，对第一极片和第二极片的压实密度进行调整，在两者仍保持在合理范围内的基础上，使得第一极片的压实密度大于第二极片的压实密度，从而使得第二极片吸收电解液的能力更高。
在一些实施例中，第一电极组件还包括第一凹槽，第二电极组件还包括第二凹槽，第一凹槽和第二凹槽均用于存储至少部分的电解液，第二凹槽的体积大于第一凹槽的体积。
在电极组件上开设凹槽，例如，在正极片或负极片上的活性物质层设置凹槽结构，该凹槽结构可以用于在接触电解液时利用液体的吸附能力使一部分的电解液残留在凹槽中。通过采用上述方案，可以使得第一电极组件上的第一凹槽和第二电极组件上的第二凹槽都可以吸附并存储一定的电解液，可以提高锂离子的迁移速度，提高电循环的性能；并且，可以使第二电极组件上的凹槽结构吸附并存储电解液的能力更强，能够吸附并存储更多的电解液。
第二方面，本申请实施例提供了一种电池，其包括：如第一方面任意实施例的电池单体。
第三方面，本申请实施例提供了一种用电装置，包括第二方面的电池，电池用于提供电能。
附图说明
下面将参考附图来描述本申请示例性实施例的特征、优点和技术效果。
图1为本申请一些实施例提供的车辆的结构示意图；
图2为本申请一些实施例提供的电池的爆炸示意图；
图3为本申请一些实施例提供的电池单体的爆炸示意图；
图4为图3中A-A向的剖视图；
图5为本申请一些实施例提供的第一电极组件和第二电极组件的结构示意图；
图6为本申请另一些实施例提供的第一电极组件和第二电极组件的结构示 意图；
图7为本申请一些实施例提供的第一极片和第二极片的展开示意图。
在附图中，附图未必按照实际的比例绘制。
附图标记
1-车辆；
10-电池、20-控制器、30-马达；
11-箱体、111-第一箱体部、112-第二箱体部、113-容纳空间；
100-电池单体、110-壳体、120-端盖、130-第一电极组件、131-第一隔离件、133-第一凹槽、140-第二电极组件、141-第二隔离件、143-第二凹槽；
X-竖直方向。
具体实施方式
为使本申请实施例的目的、技术方案和优点更加清楚，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
除非另有定义，本申请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；本申请中在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；本申请的说明书和权利要求书及上述附图说明中的术语“包括”和“具有”以及它们的任何变形，意图在于覆盖不排他的包含。本申请的说明书和权利要求书或上述附图中的术语“第一”、“第二”等是用于区别不同对象，而不是用于描述特定顺序或主次关系。
在本申请中提及“实施例”意味着，结合实施例描述的特定特征、结构或特性可以包含在本申请的至少一个实施例中。在说明书中的各个位置出现该短语并不一定均是指相同的实施例，也不是与其它实施例互斥的独立的或备选的实施例。
在本申请的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”、“附接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是直接相连，也可以通过中 间媒介间接相连，可以是两个元件内部的连通。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本申请中的具体含义。
本申请中术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本申请中字符“/”，一般表示前后关联对象是一种“或”的关系。
在本申请的实施例中，相同的附图标记表示相同的部件，并且为了简洁，在不同实施例中，省略对相同部件的详细说明。应理解，附图示出的本申请实施例中的各种部件的厚度、长宽等尺寸，以及集成装置的整体厚度、长宽等尺寸仅为示例性说明，而不应对本申请构成任何限定。
本申请中出现的“多个”指的是两个以上(包括两个)。
本申请中，电池单体可以包括锂离子二次电池单体、锂离子一次电池单体、锂硫电池单体、钠锂离子电池单体、钠离子电池单体或镁离子电池单体等，本申请实施例对此并不限定。电池单体可呈圆柱体、扁平体、长方体或其它形状等，本申请实施例对此也不限定。电池单体一般按封装的方式分成三种：柱形电池单体、方形电池单体和软包电池单体，本申请实施例对此也不限定。
本申请的实施例所提到的电池是指包括一个或多个电池单体以提供更高的电压和容量的单一的物理模块。例如，本申请中所提到的电池可以包括电池模块或电池包等。电池一般包括用于封装一个或多个电池单体的箱体。箱体可以避免液体或其他异物影响电池单体的充电或放电。
电池单体包括壳体、端盖、电极组件和电解质，端盖和壳体密封形成容纳空间，电极组件和电解液放置于容纳空间中。电极组件包括正极极片、负极极片和隔离件。电池单体主要依靠金属离子在正极极片和负极极片之间移动来工作。正极极片包括正极集流体和正极活性物质层，正极活性物质层涂覆于正极集流体的表面；正极集流体包括正极集流部和凸出于正极集流部的正极凸部，正极集流部涂覆有正极活性物质层，正极凸部的至少部分未涂覆正极活性物质层，正极凸部作为正极极耳。以锂离子电池为例，正极集流体的材料可以为铝，正极活性物质层包括正极活性物质，正极活性物质可以为钴酸锂、磷酸铁锂、三元锂或锰酸锂等。负极极片包括负极集流体和负极活性物质层，负极活性物质层涂覆于负极集流体的表面；负极集流体包括负极集流部和凸出于负极集流 部的负极凸部，负极集流部涂覆有负极活性物质层，负极凸部的至少部分未涂覆负极活性物质层，负极凸部作为负极极耳。负极集流体的材料可以为铜，负极活性物质层包括负极活性物质，负极活性物质可以为碳或硅等。为了保证通过大电流而不发生熔断，正极极耳的数量为多个且层叠在一起，负极极耳的数量为多个且层叠在一起。隔离件的材质可以为PP(polypropylene，聚丙烯)或PE(polyethylene，聚乙烯)等。此外，电极组件可以是卷绕式结构，也可以是叠片式结构，本申请实施例并不限于此。
同一个电池单体中可能设置有多个的电极组件，多个电极组件在进行正负极配对后一同放置到壳体和端盖形成的密封空间中封存。电池单体整体的循环性能、使用寿命与壳体中每一个电极组件在使用过程中的多项指标相关。申请人发现，电池单体在箱体中的摆放方式有多种，其中，有一种电池单体在使用时，壳体中的多个电极组件会呈上下堆叠状态，而在该种电池单体的使用过程中，电池单体的循环性能指标和使用寿命通常远低于预设的目标。经过申请人的进一步实验和电池拆解发现，该种电池单体中的多个电极组件呈现出了不同的寿命状态，堆叠在上方的电极组件的寿命恶化的速率远大于堆叠在下方的电极组件的寿命恶化的速率。因此，随着时间的累积，不同电极组件的状态差异日益增大，电池单体的循环性能和整体寿命也会随之快速下降。
通过申请人进一步的研究发现，上述情况是由于堆叠在上方的电极组件于与电解液的接触面积过小，从而导致该电极组件发生化学反应时产生的热量难以通过电解液传导至别处，产热的速率大于散热的速率，电极组件的温度就会持续上升，温度升高又会导致电极组件的失水速度加快，进一步加剧升温。当电极组件的温度过高时，会破坏内部的化学平衡，导致副反应，也会导致化学材料的性能退化，进而缩短电极组件和电池单体整体的循环寿命。
鉴于此，本申请实施例提供了一种电池单体，该电池单体包括有第一电极组件和第二电极组件，第一电极组件包括有第一隔离件，第二电极组件包括有第二隔离件，第二隔离件的透气度大于第一隔离件的透气度。具有该种结构的电池单体，可以使不同的电极组件具备不同的存储电解液的能力，可以设置使位于堆叠位置中下方的电极组件的电解液存储能力高于上方的电极组件的电解液存储能力，以提高电池单体整体的循环寿命。
本申请实施例描述的电池单体适用于电池以及使用电池的用电装置。
用电装置可以是车辆、手机、便携式设备、笔记本电脑、轮船、航天器、电动玩具和电动工具等等。车辆可以是燃油汽车、燃气汽车或新能源汽车，新能源汽车可以是纯电动汽车、混合动力汽车或增程式汽车等；航天器包括飞机、火箭、航天飞机和宇宙飞船等等；电动玩具包括固定式或移动式的电动玩具，例如，游戏机、电动汽车玩具、电动轮船玩具和电动飞机玩具等等；电动工具包括金属切削电动工具、研磨电动工具、装配电动工具和铁道用电动工具，例如，电钻、电动砂轮机、电动扳手、电动螺丝刀、电锤、冲击电钻、混凝土振动器和电刨等等。本申请实施例对上述用电装置不做特殊限制。
以下实施例为了方便说明，以用电装置为车辆为例进行说明。
图1为本申请一些实施例提供的车辆的结构示意图。如图1所示，车辆1的内部设置有电池10，电池10可以设置在车辆1的底部或头部或尾部。电池10可以用于车辆1的供电，例如，电池10可以作为车辆1的操作电源。
车辆1还可以包括控制器20和马达30，控制器20用来控制电池10为马达30供电，例如，用于车辆1的启动、导航和行驶时的工作用电需求。
在本申请一些实施例中，电池10不仅仅可以作为车辆1的操作电源，还可以作为车辆1的驱动电源，代替或部分地代替燃油或天然气为车辆1提供驱动动力。
图2为本申请一些实施例提供的电池10的爆炸示意图。如图2所示，电池10包括箱体11和电池单体100，电池单体100容纳于箱体11内。
箱体11用于容纳电池单体100，箱体11可以是多种结构。在一些实施例中，箱体11可以包括第一箱体部111和第二箱体部112，第一箱体部111与第二箱体部112相互盖合，第一箱体部111和第二箱体部112共同限定出用于容纳电池单体的容纳空间113。第二箱体部112可以是一端开口的空心结构，第一箱体部111为板状结构，第一箱体部111盖合于第二箱体部112的开口侧，以形成具有容纳空间113的箱体11；第一箱体部111和第二箱体部112也均可以是一侧开口的空心结构，第一箱体部111的开口侧盖合于第二箱体部112的开口侧，以形成具有容纳空间113的箱体11。当然，第一箱体部111和第二箱体部112可以是多种形状，比如，圆柱体、长方体等。
为提高第一箱体部111与第二箱体部112连接后的密封性，第一箱体部111与第二箱体部112之间也可以设置密封件，比如，密封胶、密封圈等。
假设第一箱体部111盖合于第二箱体部112的顶部，第一箱体部111亦可称之为上箱盖，第二箱体部112亦可称之为下箱体。
在电池10中，电池单体100为多个。多个电池单体100之间可串联或并联或混联，混联是指多个电池单体100中既有串联又有并联。多个电池单体100之间可直接串联或并联或混联在一起，再将多个电池单体100构成的整体容纳于箱体11内；当然，也可以是多个电池单体100先串联或并联或混联组成电池模块(图中未示出)，多个电池模块再串联或并联或混联形成一个整体，并容纳于箱体11内。电池模块中的多个电池单体100之间可通过汇流部件实现电连接，以实现电池模块中的多个电池单体100的并联或串联或混联。
请参见图3，图3为本申请一些实施例提供的电池单体100的爆炸示意图。
如图3所示，本申请提供了一种电池单体100，该电池单体100包括沿竖直方向X堆叠的第一电极组件130和第二电极组件140，其中，第一电极组件130设置于第二电极组件140的下方，第一电极组件130包括第一隔离件131，第二电极组件140包括第二隔离件141，第二隔离件141的透气度大于第一隔离件131的透气度。
本申请实施例中的电极组件除有特殊说明以外，可以为卷绕式的电极组件，也可以为叠片式的电极组件，本申请对此不做限定。为便于说明，以下内容及附图均以卷绕式的电极组件为示例说明。
第一电极组件130和第二电极组件140沿竖直方向X堆叠，即第一电极组件130和第二电极组件140是沿厚度方向并排放置的，由于壳体110中的电解液通常不会充满壳体110中的剩余空间，在重力的作用下，较多的电解液被存储于壳体110的下部。这样，就容易导致堆叠于下方的第一电极组件130与电解液接触的面积较大，并且，在使用过程中，第一电极组件130能够持续地与电解液保持较大面积的接触，因此，第一电极组件130在循环过程中所产生的热量可以通过电解液散失，而不会积聚热量；第二电极组件140在使用过程中难以接触电解液或与电解液只有较小面积的接触，热量难以散开，容易处于长期的高温状态下，因而第二电极组件140容易发生寿命恶化的问题。
第一电极组件130中通常包括有两个隔离件，第一隔离件131可以是两个隔离件中的任意一个。第二电极组件140中通常也包括有两个隔离件，第二隔离件141也可以是两个隔离件中的任意一个。
第二隔离件141的透气度大于第一隔离件131的透气度，这里需要说明的是，透气度指的是第一隔离件131或第二隔离件141整体的透气能力，具体地，可以测验相同体积的同一气体完全通过第一隔离件131和第二隔离件141分别需要的时间，第二隔离件141的透气度大于第一隔离件131的透气度即该气体完全通过第二隔离件141的时间较完全通过第一隔离件131的时间更短。当第一隔离件131和第二隔离件141的厚度一定时，第一隔离件131或第二隔离件141的透气度与其上分布的孔隙总面积相关，孔隙总面积越大，同一时间内通过的气体量越多，透气度就越高。
通过使第二隔离件141的透气度大于第一隔离件131的透气度，第二电极组件140能够在与电解液接触时借助液体的吸附能力使更多的电解液能够留存于第二隔离件141上，以使第二电极组件140存储电解液的能力高于第一电极组件130存储电解液的能力，这样，能够改善第二电极组件140寿命恶化的情况，以使电池单体100整体的循坏寿命得到延长。
请参见图3和图4，其中，图4为图3中A-A向的剖视图。
如图3和图4所示，第二隔离件141的孔隙率大于第一隔离件131的孔隙率。
孔隙率是指单位面积的第一隔离件131或第二隔离件141上孔隙总面积的占比，孔隙的数量设置较多，或者，单个孔隙的面积设置较大，都有助于提高孔隙率。因此，可以在第二隔离件141上设置较第一隔离件131更多的孔隙，也可以将第二隔离件141上的单个孔隙的尺寸设置得比第一隔离件131的尺寸更大，以使得第二隔离件141的孔隙率大于第一隔离件131的孔隙率。通过采用这样的结构，可以使得第二隔离件141存储电解液的能力较第一隔离件131存储电解液的能力更强。当电池单体100在使用过程中发生晃动、抖动时，第二隔离件141可以借由与电解液的短暂接触将更多的电解液留存于孔隙中，以改善第二电极组件141寿命恶化的现象。
请参见图5，图5为本申请一些实施例提供的第一电极组件131和第二电极组件141的结构示意图。
如图5所示，第一电极组件131和第二电极组件141均为卷绕式的电极组件，沿卷绕方向，第二隔离件141的长度L 1大于第一隔离件131的长度L 2。
当第一隔离件131和第二隔离件141上单位面积的孔隙率一定时，通过延 长第二隔离件141的长度L 2，可以增大第二隔离件141的孔隙总面积，使第二隔离件141的长度L 2大于第一隔离件L 1的长度，可以使第二隔离件141的孔隙总面积大于第一隔离件131的孔隙总面积，使得第二隔离件141可以在孔隙中存储更多的电解液，以均衡电池单体100整体的温升能力，延缓第二电极组件141的寿命恶化，最终延长电池单体100整体的使用寿命。
请参见图6，图6为本申请另一些实施例提供的第一电极组件131和第二电极组件141的结构示意图。
如图6所示，沿卷绕方向，第二隔离件141的卷绕圈数N 1大于第一隔离件131的卷绕圈数N 2。
卷绕一圈是指从隔离件上平行于宽度方向的某一直线出发，沿电极组件的卷绕方向延伸至隔离件上平行于宽度方向的另一直线，通过连接两条直线形成的平面能够经过电极组件的中心，分布于两条直线之间的隔离件即为卷绕一圈的隔离件。
在电极组件中，相邻圈的隔离件之间可以形成狭长的间隙，该间隙可以在毛细作用下吸附一定的电解液并留存，间隙沿卷绕方向的尺寸越大，能为留存电解液提供的空间越多。第二隔离件141的卷绕圈数N 1大于第一隔离件131的卷绕圈数N 2,可以使得第二隔离件141形成沿卷绕方向尺寸较大的间隙，这样，第二隔离件141可以利用该间隙留存较多的电解液，以延缓第二隔离件141的寿命恶化，使得第二隔离件141的寿命能够被延长以均衡电池单体100整体的使用寿命。
在本申请的一些实施例中，可选地，第一电极组件131还包括第一极片，第二电极组件141还包括第二极片，第一极片和第二极片极性相同，第一极片的压实密度大于第二极片的压实密度。
极片的压实密度是指活性物质的体积占总体积的比例，极片的压实密度用于表征极片的体积内被活性物质所充填的程度，其反映了活性物质分布的致密程度。极片的压实密度会影响极片的孔隙率，从而影响极片对电解液的吸收量，具体地，极片的压实密度越大，极片的孔隙率就越小，对电解液的吸收量就越低。在电极组件中，由于正极片和负极片上所采用的活性物质不同，基于此，对正极片和负极片的压实密度要求范围也不同。
在第一极片和第二极片的极性相同的情况下，使第一极片的压实密度大于 第二极片的压实密度，这样，可以使得第二极片的孔隙率大于第一极片的孔隙率，最终使得第二极片对电解液的吸收量大于第一极片对电解液的吸收量，以延缓第二极片的寿命恶化。
具体地，在本申请的一些实施例中，当第一极片和第二极片均为正极片时，第一极片的压实密度可以为3.2g/cm 3-3.5g/cm 3，第二极片的压实密度可以为3.0g/cm 3-3.25g/cm 3，或者，当第一极片和第二极片为负极片时，第一极片的压实密度可以为1.55g/cm 3-1.7g/cm 3，第二极片的压实密度可以为1.4g/cm 3-1.55g/cm 3。
请参见图7，图7为本申请一些实施例提供的第一极片和第二极片的展开示意图。
如图7所示，在本申请的一些实施例中，第一电极组件130还包括第一凹槽133，第二电极组件140还包括第二凹槽143，第一凹槽133和第二凹槽143均用于存储至少部分的电解液，第二凹槽143的体积大于第一凹槽133的体积。
第一电极组件130可以设置有第一凹槽133，第一凹槽133可以设置于第一电极组件130的正极片或负极片上，第一凹槽133可以为正极片或负极片上涂覆活性物质的厚度较小的区域，该区域较其他区域的涂覆厚度小，使得该区域在极片的表面呈凹陷的形式，或者，该区域也可以为未涂覆活性物质而裸露的集流体。
第二电极组件140可以设置有第二凹槽143，第二凹槽143可以设置于第二电极组件140的正极片或负极片上，第二凹槽143可以为正极片或负极片上涂覆活性物质的厚度较小的区域，该区域较其他区域的涂覆厚度小，使得该区域在极片的表面呈凹陷的形式，或者，该区域也可以为未涂覆活性物质而裸露的集流体。
当第一电极组件130或第二电极组件140接触电解液时，依靠电解液的吸附力，可以将部分的电解液留存于第一凹槽133或第二凹槽143中。使第二凹槽143的体积大于第一凹槽133的体积，这样，第二凹槽143可以在接触电解液时存储较第一凹槽133多的电解液，这样，第二电极组件140反应产生的部分热量可以通过电解液传导扩散，以降低第二电极组件140的使用温度从而缓解第二电极组件140的寿命恶化。
需要说明的是，在不冲突的情况下，本申请中的实施例及实施例中的特征 可以相互组合。
最后应说明的是：以上实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换，但这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的精神和范围。

Claims (9)

  1. 一种电池单体，其特征在于，包括：
    沿竖直方向堆叠的第一电极组件和第二电极组件，所述第一电极组件设置于所述第二电极组件的下方，
    所述第一电极组件包括第一隔离件，所述第二电极组件包括第二隔离件，所述第二隔离件的透气度大于所述第一隔离件的透气度。
  2. 根据权利要求1所述的电池单体，其特征在于，所述第二隔离件的孔隙率大于所述第一隔离件的孔隙率。
  3. 根据权利要求1-2中任一项所述的电池单体，其特征在于，所述第一电极组件和所述第二电极组件均为卷绕式的电极组件，沿卷绕方向，所述第二隔离件的长度大于所述第一隔离件的长度。
  4. 根据权利要求3所述的电池单体，其特征在于，沿所述卷绕方向，所述第二隔离件的卷绕圈数大于所述第一隔离件的卷绕圈数。
  5. 根据权利要求1-4中任一项所述的电池单体，其特征在于，所述第一电极组件还包括第一极片，所述第二电极组件还包括第二极片，所述第一极片和所述第二极片极性相同，所述第一极片的压实密度大于所述第二极片的压实密度。
  6. 根据权利要求5所述的电池单体，其特征在于，所述第一极片和所述第二极片均为正极片，所述第一极片的压实密度为3.2g/cm 3-3.5g/cm 3，所述第二极片的压实密度为3.0g/cm 3-3.25g/cm 3；或者，
    所述第一极片和所述第二极片均为负极片，所述第一极片的压实密度为1.55g/cm 3-1.7g/cm 3,所述第二极片的压实密度为1.4g/cm 3-1.55g/cm 3。
  7. 根据权利要求1-6中任一项所述的电池单体，其特征在于，所述第一电极组件还包括第一凹槽，所述第二电极组件还包括第二凹槽，所述第一凹槽和所述第二凹槽均用于存储至少部分的电解液，所述第二凹槽的体积大于所述第 一凹槽的体积。
  8. 一种电池，其特征在于，所述电池包括如权利要求1-7中任一项所述的电池单体。
  9. 一种用电装置，其特征在于，包括根据权利要求8所述的电池，所述电池用于提供电能。
PCT/CN2022/105159 2021-09-28 2022-07-12 电池单体、电池和用电装置 WO2023050972A1 (zh)

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