CN213071299U

CN213071299U - Secondary battery with electrolyte diffusion promoting function

Info

Publication number: CN213071299U
Application number: CN202021509224.2U
Authority: CN
Inventors: 郭永兴; 卢林
Original assignee: Jiangxi Star Energy Co ltd
Current assignee: Jiangxi Star Energy Co ltd
Priority date: 2020-07-27
Filing date: 2020-07-27
Publication date: 2021-04-27
Anticipated expiration: 2030-07-27

Abstract

The utility model relates to a battery preparation technical field, in particular to secondary battery with short diffusion function of electrolyte, the battery includes: an electrode assembly comprising at least two electrodes; a case having a cavity therein to accommodate an electrolyte, the electrode assembly being disposed within the cavity; electrolyte diffusion promotion means capable of driving the electrolyte to flow. Through the utility model provides a pair of secondary battery with short diffusion function of electrolyte can solve among the prior art problem and the local problem of generating heat and the heat dissipation difficulty that thick electrode brought of lithium ion transmission difficulty between the positive negative pole in thick electrode design current collector side electrolyte.

Description

Secondary battery with electrolyte diffusion promoting function

Technical Field

The utility model relates to a battery preparation technical field, in particular to secondary battery with short diffusion function of electrolyte.

Background

The current energy storage technologies mainly include mechanical energy storage, chemical energy storage, electromagnetic energy storage, and phase change energy storage. Compared with other modes, the electrochemical energy storage has the advantages of convenience in use, less environmental pollution, no region limitation, no Carnot cycle limitation on energy conversion, high conversion efficiency, high specific energy and specific power and the like. The traditional electrochemical energy storage is mainly based on a lead-acid battery, the service life of the lead-acid battery is generally 2-3 years, and the service life of the wind energy and solar energy station cannot be matched at all. Since the commercialization of 1991, lithium ion batteries have rapidly developed and have dominated the digital and electric automobile fields. The vigorous development of wind-solar power generation in recent years has greatly pulled the development of energy storage lithium ion batteries and posed more challenges.

The capacity of the lithium ion battery monomer for the energy storage power station produced at present is basically less than 500Ah, the design concepts of 3C and EV are maintained, the volume and mass energy density are pursued, and the internal lean solution of the monomer cannot realize the internal monitoring and maintenance of the monomer. In order to design the energy storage capacity and the voltage, the energy storage power station needs to carry out a large amount of series-parallel connection work, and the monitoring cost of the single battery cell is greatly increased from dozens of to hundreds of watt hours of the single battery to dozens of to hundreds of megawatt hours of the single battery. Too small a cell capacity can reduce cell production efficiency. The thick electrode design can greatly increase the active material load on the current collector, greatly increase the capacity of a monomer battery core and reduce the ratio of inactive components, thereby improving the energy density of the battery and reducing the cost. However, increasing the thickness of the electrode prolongs the electron and lithium ion transmission path, increases the battery impedance, and has a series of problems such as poor battery rate performance and electrode reaction kinetics, low bonding strength of the electrode coating, and easy falling off.

Transport of lithium ions, comprising 3 parts: 1) the transmission process of lithium ions in the electrolyte, particularly the distribution of lithium ions in the active material on the collector side; 2) the diffusion process of lithium through the SEI film is affected by the SEI film composition, thickness, etc.; 3) the diffusion of lithium inside the solid particles of the electrode material is related to the basic characteristics of the raw material. As the thickness of the electrode increases, the transport of lithium ions in the pores of the electrode becomes the rate-determining step in the charging and discharging process of the battery, and therefore, prior art thick electrode designs have focused on improvements to the active material layer, such as, for example, pore size and its distribution, pore connectivity, pore throat characteristics, and the like. Improvements to the active materials have in turn led to a series of problems, for example, a reduction in the energy density of the battery, a considerable reduction in the bonding strength of the coating on the current collector.

In view of the above, it is necessary to provide a new concept to solve the above problems in the design of thick electrodes.

Disclosure of Invention

Based on this, the utility model aims at providing a secondary battery with short diffusion function of electrolyte can solve among the prior art problem and the local difficult problem that generates heat and dispels the heat that thick electrode brought of lithium ion transmission difficulty between the positive negative pole in thick electrode design current collector side electrolyte.

In order to solve the above technical problem, the utility model provides a secondary battery with short diffusion function of electrolyte, the battery includes:

the electrolyte tank comprises a shell, a first electrode and a second electrode, wherein a cavity for accommodating electrolyte is formed in the shell;

an electrode assembly disposed within the cavity, the electrode assembly including at least two electrodes;

electrolyte diffusion promoting device for driving the electrolyte to flow.

As an optional technical solution, the electrolyte diffusion promoting device is arranged outside the shell;

two ends of the electrolyte diffusion promoting device are respectively communicated with the cavity through pipelines;

the pipes comprise a first pipe and a second pipe;

the first end of the first pipeline is communicated with the outlet end of the electrolyte diffusion promoting device, and the second end of the first pipeline is communicated with the cavity; the first end of the second pipeline is communicated with the cavity, and the second end of the second pipeline is communicated with the inlet end of the electrolyte diffusion promoting device.

As an optional technical solution, the electrode is divided into a positive electrode plate and a negative electrode plate according to the difference of the polarities of the surface active materials, and the positive electrode plate and the negative electrode plate are stacked in the cavity in a crossed manner along the thickness direction of the electrode.

As an alternative solution, the electrode comprises a current collector and an active material layer containing an active material disposed on at least one outer surface of the current collector;

wherein the current collector comprises:

an interlayer space configured to accommodate an electrolyte;

a current collector portion having at least one active material mounting surface configured to seat an active material;

at least one through hole communicated with the interlayer space is formed in the active material arrangement surface, so that lithium ions in the electrolyte can enter the active material through the through hole and/or lithium ions in the active material can enter the electrolyte through the through hole;

the second end of the first pipeline is arranged beside the interlayer space, so that the electrolyte diffusion promoting device can drive the electrolyte in the interlayer space to flow.

As an optional technical solution, the current collecting part includes:

the first current collecting part and the second current collecting part are separated to form the interlayer space;

the first collecting part and the second collecting part are respectively provided with a plurality of through holes;

the interlayer space is provided with at least one connecting part for connecting the first current collecting part and the second current collecting part;

the connecting part comprises a connecting strip, and the connecting strip is arranged at the edge of the interlayer space and encloses the interlayer space, so that the interlayer space is closed in the height direction;

in the electrode assembly, all electrodes are connected in series end to end by adopting short pipes, the short pipes are arranged at the ends of the electrodes in the length direction and are communicated with the interlayer spaces of the electrodes, so that electrolyte in the interlayer spaces of every two adjacent electrodes can flow, and the two short pipes arranged on the same electrode are far away from each other in the length direction of the electrode;

the interlayer space of one tail end electrode in the thickness direction of the electrode assembly is communicated with a second end of a first pipeline, and the second end of the first pipeline is far away from a short pipe arranged on the electrode in the length direction of the electrode; the interlayer space of the electrode at the other end of the electrode assembly in the thickness direction is communicated with the first end of the second pipeline, and the first end of the second pipeline is far away from the short pipe arranged on the electrode in the length direction of the electrode.

As an alternative solution, when the active material layer of the electrode assembly is parallel to the plane of the bottom of the case, the vertical height of the second end of the first tube is higher than that of the first end of the second tube.

As an optional technical scheme, the active material setting surface is divided into two non-punching areas and a punching area according to whether through holes are distributed or not, the punching area is located in the middle of the length direction of the current collecting part, and the two sides of the punching area are the non-punching areas; the two ends of the short pipe, the second end of the first pipeline and the first end of the second pipeline are arranged in the non-punching area.

As an optional technical solution, a part of the first pipe located in the cavity is communicated with a plurality of branch pipes, the branch pipes are mutually connected in parallel and arranged on the first pipe, the number of the branch pipes is matched with the number of the electrodes in the electrode assembly, and one end of each branch pipe, which is far away from the first pipe, is arranged beside an interlayer space of the electrode, so that the electrolyte diffusion promoting device can drive the electrolyte in the electrode interlayer space to flow; the first end of the second pipeline is arranged at the top of the cavity.

As an alternative solution, the active material layer of the electrode assembly is parallel to the plane of the bottom of the case; or the active material layer of the electrode assembly is perpendicular to the plane of the bottom of the case.

As an optional technical solution, the first current collecting part and the second current collecting part are arranged in parallel with each other;

preferably, the first current collecting part and the second current collecting part are both planar structures;

preferably, the first current collecting part and the second current collecting part are rectangular structures with the same size and shape;

preferably, the connecting portion is vertically disposed on a plane of the first collecting portion.

As an optional technical solution, the connecting portion further includes a connecting pillar;

preferably, the connecting columns are uniformly distributed in the interlayer space.

As an optional technical scheme, the device also comprises an insulating frame, wherein the insulating frame is arranged inside the shell; and the insulating frame is disposed outside the electrode assembly;

the shape of the insulating frame is matched with that of the electrode assembly, strip-shaped through holes are formed in two opposite surfaces of the insulating frame, at least two electrodes are respectively inserted into the strip-shaped through holes of the insulating frame, and two ends of each electrode are exposed out of the insulating frame.

As an optional technical scheme, the device also comprises a positive electrode bus bar and a negative electrode bus bar;

the bus bar is provided with a first surface and a second surface which are opposite, and the first surface is provided with at least one conductive bar for electrically connecting with the current collecting part of the electrode; the second surface is provided with a convex conducting plate, the conducting plate is perpendicular to the second surface, the conducting plate inserts the lateral wall of casing, just the conducting plate is in the casing stretches out outside and forms positive terminal or negative terminal.

As an optional technical solution, the bus bar is a rigid structure, and the bus bar is fixedly connected with the current collecting portion, so that the electrode assembly and the insulating frame can be fixed inside the case.

As an optional technical solution, the first current collecting part and the second current collecting part are both rigid structures, and the thickness of the first current collecting part and the thickness of the second current collecting part are independent ranges from 0.05 mm to 0.5 mm;

preferably, the value range of the interlayer space height is 0.01-1 mm.

As an optional technical scheme, the thickness of the active material layer ranges from 0.1mm to 10 mm;

preferably, the thickness of the positive active material layer ranges from 0.1mm to 0.5 mm; and/or the thickness of the negative active material layer ranges from 0.1mm to 0.4 mm.

As an optional technical solution, the battery is a lithium ion battery; preferably, the liquid injection coefficient of the lithium ion battery is 5.0-20.0; more preferably, the lithium ion battery is a lithium iron phosphate battery; and/or the battery is a battery for an energy storage system or a power battery for a vehicle.

Compared with the prior art, the utility model, the beneficial effect who has is: the application provides a secondary battery with promote diffusion function of electrolyte, this battery has the promote diffusion equipment of electrolyte, the promote diffusion equipment of this electrolyte can drive the mobile diffusion of electrolyte in the battery chamber, through the diffusion of electrolyte in the drive chamber, can make the local high concentration lithium ion that positive pole/negative pole gathered exchange with other position electrolytes with faster speed, thereby improve the charge-discharge performance of battery, and can effectively distribute the heat between positive pole/negative pole fast and detach, reduce the harm that local overheat brought. Further, in the application, the interlayer space of the positive electrode plate of the battery and the interlayer space of the negative electrode plate of the battery are directly communicated by the connection of the short pipe, the first pipeline and the second pipeline, and under the action of the electrolyte diffusion promoting device, the high-concentration and low-concentration electrolyte contained in the interlayer space of the positive electrode plate and the interlayer space of the negative electrode plate directly performs an exchange action, so that the transmission of lithium ions in the electrolyte on the collector side between the positive electrode and the negative electrode is accelerated.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

fig. 1 is an exploded schematic view of a secondary battery having an electrolyte diffusion promoting function according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of an embodiment of a secondary battery having an electrolyte diffusion promoting function provided in the present application;

FIG. 3 is a schematic view of the internal structure of FIG. 2 in a front view direction;

FIG. 4 is a schematic structural diagram of the insulating frame of FIG. 2;

FIG. 5 is a schematic structural diagram of another embodiment of a secondary battery having an electrolyte diffusion promoting function according to the present application;

FIG. 6 is a schematic top view of the internal structure of FIG. 5;

FIG. 7 is a schematic structural diagram of the insulating frame of FIG. 5;

fig. 8 is a schematic structural diagram of another embodiment of a secondary battery having an electrolyte diffusion promoting function provided in the present application;

FIG. 9 is a schematic view of a face of a busbar;

FIG. 10 is a schematic view of another side of the bus bar;

fig. 11 is a schematic structural diagram of a current collector C1 for a thick electrode according to an embodiment of the present disclosure;

fig. 12 is a partial enlarged view of a portion M in fig. 11;

fig. 13 is a schematic half-sectional view of a current collector C1 for a thick electrode according to an embodiment of the present disclosure;

fig. 14 is a schematic view of the connection and via arrangement on the current collector in one embodiment;

fig. 15 is a schematic structural view of a connection portion and a through hole on a current collector arranged in another embodiment;

fig. 16 is a schematic structural view of a connection portion and a through hole on a current collector arranged in another embodiment;

fig. 17 is a schematic structural view of a connection portion and a through hole on a current collector arranged in another embodiment;

fig. 18 is a schematic structural view of a connection portion and a through hole on a current collector arranged in another embodiment;

fig. 19 is a schematic structural diagram of an electrode P1 provided in the present embodiment;

fig. 20 is a schematic structural view of a connection portion and a through hole on a current collector arranged in another embodiment;

FIG. 21 is a graph of cycling performance for batteries of group A, group B and group C;

reference numerals: battery B1, electrode assembly Q1, electrode P1, positive electrode plate P11, negative electrode plate P12, gap 13, current collector C1, current collector 2, first current collector 21, second current collector 22, through-hole 212, connecting portion 23, connecting post 231, connecting bar 232, active material disposing surface 26, punched area 261, non-punched area 262, active material layer-3, first pipe 43, second pipe 44, short pipe 45, branch pipe 46, leak-proof material layer-5, case 6, cavity 61, insulating frame 62, strip-shaped hole 621, through-hole 622, bus bar 63, positive electrode bus bar 63-1, negative electrode bus bar 63-2, first surface 631, second surface 632, conductive bar 633, conductive plate 634, top plate 64, mounting hole 641, side wall 65, side wall opening 651, air suction port 69, interlayer space-7, electrolyte diffusion promoting device 811, 91, connecting pipe 92, connection pipe 92, and short pipe fitting, A main duct 93 and a branch duct 94.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the application, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In the description of the present application, it should be understood that the terms "first", "second", etc. are used to define the components, and are used only for the convenience of distinguishing the corresponding components, and if not otherwise stated, the terms have no special meaning, and thus, should not be construed as limiting the scope of the present application.

In the description of the present application, it is to be understood that the orientation or positional relationship indicated by the directional terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc., are generally based on the orientation or positional relationship shown in the drawings, and are used for convenience of description and simplicity of description only, and in the case of not making a reverse description, these directional terms do not indicate and imply that the device or element being referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore, should not be considered as limiting the scope of the present application; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.

The secondary battery with the electrolyte diffusion promoting function adopts the electrolyte diffusion promoting device 81, the electrolyte can circularly flow and diffuse in the cavity 61 of the battery, the state that the electrolyte of the traditional lithium ion battery flows slowly or hardly flows can be changed, the lithium ion concentration difference in the electrolyte near the anode and the cathode is effectively reduced, and the heat near the anode is diffused to other parts in the cavity to prevent the local overheating of the battery in the charging and discharging process. The application provides a secondary battery structure with promote diffusion function of electrolyte is fit for being used for lithium ion battery, is particularly suitable for the lithium ion battery that has big, thick electrode design, and is especially suitable for as battery or automobile-used power battery for the energy storage system. The present application is described in detail below with reference to the accompanying drawings.

According to fig. 1 to 20, the present application provides a secondary battery having an electrolyte diffusion promoting function, the battery B1 includes a case 6, the case 6 has a cavity 61 therein for accommodating an electrolyte, an electrode assembly Q1 is provided in the cavity 61, the electrode assembly Q1 includes at least two electrodes P1; the electrolyte diffusion promoting device 81 can drive the electrolyte to flow, the concentration of the electrolyte around the positive/negative electrode active material can be kept more stable through the diffusion of the electrolyte in the driving cavity 61, so that the concentration polarization is reduced, the charging and discharging performance of the battery is improved, the heat between the positive electrode and the negative electrode can be effectively and rapidly dissipated, and the harm caused by local overheating is reduced.

According to some specific embodiments, in order to facilitate maintenance of the electrolyte diffusion promotion device 81, the electrolyte diffusion promotion device 81 is disposed outside the housing 6; two ends of the electrolyte diffusion promoting device 81 are respectively communicated with the cavity 61 through pipelines. Specifically, the conduits include a first conduit 43 and a second conduit 44; the first end of the first pipeline 43 is communicated with the outlet end of the electrolyte diffusion promoting device 81, and the second end of the first pipeline 43 is communicated with the cavity 61; the first end of the second pipe 44 is communicated with the cavity 61, and the second end of the second pipe 44 is communicated with the inlet end of the electrolyte diffusion promoting device 81.

Specifically, the electrolyte diffusion promoting device 81 may be a peristaltic pump, for example, as long as the electrolyte in the cavity 61 can be driven to flow. The electrolyte diffusion promoting device 81 can be mounted on the top plate 64 of the housing 6, and the first pipe 43 and the second pipe 44 are respectively inserted into the cavity 61 through the two mounting holes 641 on the top plate 64, so that the electrolyte diffusion promoting device 81 can access the electrolyte in the cavity 61.

According to other specific embodiments, the electrode assembly Q1 includes at least two electrodes P1, and the electrode P1 is divided into a positive electrode plate P11 and a negative electrode plate P12 according to the polarity of the surface active material thereof, and the positive electrode plate P11 and the negative electrode plate P12 are stacked in the thickness direction of the electrode P1 in the cavity 61 in a crossing manner. It is understood that the manner of interleaving described herein refers to the manner of one layer of positive plate P11 followed by one layer of negative plate P12, and vice versa, so long as the positive plate P11 or the negative plate P12 are not directly adjacent to the same polarity electrode. The lamination arrangement referred to in the present application means that the electrodes P1 are arranged in order in one direction, and it is not limited to whether or not two adjacent electrodes P1 need to be in direct contact with each other.

According to another embodiment provided herein, which relates to the structure of the electrode P1 in the secondary battery with electrolyte diffusion promoting function, the electrode P1 comprises a current collector C1; and an active material layer 3 containing an active material disposed on at least one outer surface of the current collector C1; and the thickness of the active material layer 3 ranges from 0.1mm to 10mm, and the thick electrode defined in the application means that the thickness of the active material layer on the electrode is larger than that of a conventional electrode, and more specifically, the thick electrode defined in the application means that the thickness of the active material layer 3 on the electrode is larger than 0.1 mm.

In some preferred embodiments, as shown in fig. 19, the utilization rate of the current collector C1 may be improved by providing an active material layer 3 on both outer surfaces of the current collector C1, the active material layer 3 being provided on the punching regions 261 of the first current collecting portion 21 and the second current collecting portion 22. The active material layer 3 may be formed on the outer surface of the current collector C1 by bonding or coating, the active material layer 3 may be a positive electrode active material or a negative electrode active material, and examples of applications of the positive electrode active material include compounds capable of reversibly deintercalating and intercalating lithium ions, such as lithium cobaltate, lithium manganate, lithium nickelate and ternary materials having a layered structure; also included are lithium nickel manganese oxide having a spinel structure and lithium iron phosphate having an olivine structure. Examples of applications of the negative electrode active material include a carbon material capable of intercalating and deintercalating lithium ions, lithium metal, silicon, and tin.

Specifically, the current collector C1 in the present application employs an innovative current collector design, which includes an interlayer space 7 configured to accommodate an electrolyte; a header 2, said header 2 having at least one active material placement surface 26 configured to seat an active material; wherein the active material disposing surface 26 is opened with at least one through hole 212 communicating with the interlayer space 7, so that lithium ions in the electrolyte can enter the active material through the through hole 212 and/or lithium ions in the active material can enter the electrolyte through the through hole 212. The size and shape of the through-hole 212 are not particularly limited, and lithium ions may pass through the through-hole. In a preferred embodiment, a plurality of through holes 212 are formed on both the first collecting portion 21 and the second collecting portion 22. In order to enable the electrolyte diffusion promoting device 81 to directly act on the electrolyte in the interlayer space 7, the second end of the first pipe 43 is arranged beside the interlayer space 7, so that the electrolyte diffusion promoting device 81 can drive the electrolyte in the interlayer space 7 to flow.

Fig. 12 is a partial enlarged view of a portion M in fig. 11, and it can be seen from fig. 12 that the current collecting portion 2 includes a first current collecting portion 21 and a second current collecting portion 22, and the first current collecting portion 21 and the second current collecting portion 22 are separated to form the interlayer space 7; at least one connecting part 23 connecting the first collecting part 21 and the second collecting part 22 is arranged at the edge or inside of the interlayer space 7.

According to some specific embodiments, in order to enable direct transport exchange of lithium ions in the interlayer space 7 of the positive electrode plate P11 and the interlayer space 7 of the negative electrode plate P12, the schemes are shown in fig. 2-7, the current collector C1 structure is shown in fig. 20, according to fig. 20, the current collector C1 structure is shown, the edge of the interlayer space 7 is provided with a connecting part 23 for connecting the first current collecting part 21 and the second current collecting part 22, the connecting part 23 comprises a connecting bar 232, and the connecting bar 232 is arranged at the edge of the interlayer space 7 and surrounds the interlayer space 7, so that the interlayer space 7 is closed in the height direction; 2-7, wherein, in an electrode assembly Q1, the electrode assembly Q1 is composed of all electrodes P1 connected end to end in series by short tubes 45, the short tubes 45 are arranged at the ends of the electrode P1 in the length direction and communicate with the interlayer space 7 of the electrode P1, so that the electrolyte in the interlayer space 7 of two adjacent electrodes P1 can flow, and two short tubes 45 arranged on the same electrode P1 are arranged away from each other in the length direction of the electrode P1; the interlayer space 7 of the end electrode P1 in the thickness direction of the electrode assembly Q1 communicates with the second end of the first conduit 43, and the second end of the first conduit 43 is away from the short tube 45 provided on the electrode P1 in the length direction of the electrode P1; the electrode P1 at the other end in the thickness direction of the electrode assembly Q1 has its sandwiching space 7 communicating with the first end of the second conduit 44, and the first end of the second conduit 44 is away from the short tube 45 provided on the electrode P1 in the length direction of the electrode P1.

The operation principle of the preferred embodiment will be described below by taking as an example a charging process of a lithium ion battery, in which during charging, Li + is extracted from the positive electrode and inserted into the negative electrode through the electrolyte, and the lithium ions in the electrolyte around the positive electrode are higher than the average value, that is, the electrolyte around the interlayer space 7 of the positive electrode plate P11 and the outer surface of the active material layer 3 of the positive electrode is in a lithium-rich state; the lithium ions in the electrolyte around the negative electrode are lower than the average value, that is, the electrolyte around the interlayer space 7 of the negative electrode plate P12 and the outer surface of the active material layer 3 of the negative electrode is in a lithium-deficient state. The distance from lithium ions in the interlayer space 7 of the positive polar plate P11 to the interlayer space 7 of the negative polar plate P12 is longer, and the time for recovering the lithium ion concentration of the electrolyte in the interlayer space 7 of the positive polar plate P11 and the negative polar plate P12 is longer; the interlayer space 7 of the positive electrode plate P11 and the interlayer space 7 of the negative electrode plate P12 are communicated through the short pipe 45, the first pipeline 43 and the second pipeline 44 are used for communicating the electrolyte diffusion promoting device 81 with the interlayer space 7 of the two electrodes P1 at the tail ends of the electrode assembly Q1, after the electrolyte diffusion promoting device 81 is started, high-concentration lithium electrolyte in the interlayer space 7 of the positive electrode plate P11 and low-concentration lithium electrolyte in the interlayer space 7 of the negative electrode plate P12 are in direct contact, the concentrations of the electrolytes in the interlayer spaces 7 of the positive electrode plate P11 and the negative electrode plate P12 are rapidly balanced, the time for restoring balance of the electrolytes in the interlayer spaces 7 of the positive electrode plate P11 and the interlayer space 7 of the negative electrode plate P12 is greatly shortened, and the problem that lithium ions in the electrolytes on the thick electrode collector side of the current collector are difficult to transmit between the positive electrode and the negative electrode is solved.

According to some preferred embodiments, as shown in fig. 2-4, an arrangement mode of the electrode assembly Q1 in the cavity 61 is shown, when the active material layer 3 of the electrode assembly Q1 is parallel to the plane of the bottom of the casing 6, the second end of the first pipe 43 is higher than the first end of the second pipe 44 vertically during the battery use, and at this time, the flowing direction of the electrolyte between the upper and lower electrodes P1 is consistent with the direction of the driving force generated by the electrolyte diffusion promoting device 81, and the electrolyte diffusion promoting device 81 has a driving force capable of exerting a better electrolyte driving effect.

Fig. 3-7 show another arrangement of the electrode assembly Q1 in the cavity 61, in which the active material layer 3 of the electrode assembly Q1 is perpendicular to the plane of the bottom of the casing 6, and at this time, the active material layer 3 does not generate a force perpendicular to the large surface of the current collector C1 on the current collector C1 during use, so as to prevent the current collector C1 from deforming or breaking during use.

According to other specific embodiments, as shown in fig. 8, the part of the first pipe 43 located in the cavity 61 is communicated with a plurality of branch pipes 46, the branch pipes 46 are mutually connected in parallel with each other and are arranged on the first pipe 43, the number of the branch pipes 46 is matched with the number of the electrodes P1 in the electrode assembly Q1, one end of the branch pipe 46 far away from the first pipe 43 is arranged beside the interlayer space 7 of the electrode P1, so that the electrolyte diffusion promoting device 81 can drive the electrolyte in the interlayer space 7 of the electrode P1 to flow; the first end of the second pipe 44 is disposed at the top of the cavity 61. In this design, the electrolyte diffusion promoting device 81 accelerates the exchange between the electrolyte in the interlayer space 7 of each electrode P1 and the electrolyte around the electrode assembly Q1, and shortens the time required for the lithium ion concentration in the cavity 61 to return to the normal state, thereby improving the charge and discharge performance of the battery.

The working principle of the preferred embodiment is illustrated below by taking as an example the charging process of a lithium ion battery, during which Li is charged⁺The lithium ions are extracted from the positive electrode and are inserted into the negative electrode through the electrolyte, the lithium ions in the electrolyte around the positive electrode are higher than the average value, namely the electrolyte around the interlayer space 7 of the positive electrode plate P11 and the outer surface of the active material layer 3 of the positive electrode is in a lithium-rich state; the lithium ions in the electrolyte around the negative electrode are lower than the average value, that is, the electrolyte around the interlayer space 7 of the negative electrode plate P12 and the outer surface of the active material layer 3 of the negative electrode is in a lithium-deficient state. The distance from lithium ions in the interlayer space 7 of the positive polar plate P11 to the interlayer space 7 of the negative polar plate P12 is longer, and the time for recovering the lithium ion concentration of the electrolyte in the interlayer space 7 of the positive polar plate P11 and the negative polar plate P12 is longer; through the action of the electrolyte diffusion promoting device 81, the high-concentration lithium ion electrolyte in the interlayer space 7 of the positive pole plate P11 can be driven to be discharged out of the interlayer space 7, the electrolyte around the positive pole plate P11 is supplemented into the interlayer space 7, and when the lithium ion concentration of the electrolyte in the interlayer space 7 of the positive pole plate P11 is rapidly balanced, the heat in the electrolyte is also dissipated. Accordingly, the lithium ion concentration of the low-concentration lithium ion electrolyte in the interlayer space 7 of the negative electrode plate P12 will be balanced quickly.

The structure in current collector C1 to which the present application relates is further described below, and fig. 11-20 illustrate the structure of current collector C1:

in the present application, the connection portion 23 and the first and

second collecting portions

21 and 22 may be manufactured by an integral casting process or a bending process. In addition, a plurality of through holes 212 allowing lithium ions to pass through are formed in each of the first current collecting portion 21 and the second current collecting portion 22, so that at least part of the through holes 212 are ensured to be communicated with the interlayer space 7, and lithium ions in the active material on the current collecting portion 2 side can pass through the through holes 212 and enter and exit the interlayer space 7.

Compared with the conventional current collector in the prior art, the innovative current collector C1 provided by the application has the current collector C1 with the interlayer space 7, when the assembled battery is used, the interlayer space 7 is filled with electrolyte, compared with the poor liquid state of the conventional lithium ion battery, the current collector C1 is in the rich liquid state, the through hole 212 formed in the surface of the current collector C is communicated with the interlayer space 7 in the middle to form a unique lithium ion transport passage, the lithium ion transport distance is reduced by half, taking the first current collector part 21 as an example, after the active material is coated, the lithium ions in the active material on the side of the first current collector part 21 can flow into the electrolyte through the passage between the through hole 212 and the interlayer space 7, the transport distance of the lithium ions in the active material particles can be remarkably shortened by half, the problem of long lithium ion transport path of the active material on the side of the current collector in the conventional art is changed, and the interlayer space 7 is designed, the poor liquid state of the traditional lithium ion battery is changed, the active material can be well soaked, the diffusion speed of lithium ions in the active material is improved, the diffusion speed of the lithium ions in the electrolyte can be improved by arranging the electrolyte diffusion promoting device, and on the basis, the design of a thick electrode of the battery can be realized.

According to an embodiment of the present application, as shown in fig. 20, on the active material disposition surface 26 of the current collecting part 2, there are divided two non-punched areas 262 and one punched area 261 depending on whether there are through holes 212 distributed, the punched area 261 being located at the middle of the length direction of the current collecting part 2, the punched area 261 being flanked by the non-punched areas 262; also, it is preferable that both outer surfaces of the collecting portion 2 are designed as described above to reduce the proportion of inactive materials. The short tube 45 and the first and

second conduits

43, 44 are disposed in the non-perforated region 262. The punching zone 261 is a rectangular zone, the length L of the punching zone 261₁1/2-4/5 of the length L of the first collecting portion 21.

As a specific embodiment, in order to facilitate mass production of the current collector C1 and subsequent arrangement of active materials, fig. 11 to 12 of the present application illustrate a current collector C1 in which the first current collecting portion 21 and the second current collecting portion 22 are arranged in parallel up and down; the first current collecting part 21 and the second current collecting part 22 are both planar structures; the first current collecting part 21 and the second current collecting part 22 are rectangular structures with the same size and shape; the connecting portion 23 is vertically disposed on the plane of the first current collecting portion 21.

In order to ensure that the manufactured current collector C1 has a relatively stable capacity in the use process and facilitates the arrangement of active materials, the first current collecting part 21 and the second current collecting part 22 are both rigid structures, and the thickness of the first current collecting part 21 and the thickness of the second current collecting part 22 are respectively and independently in a range of 0.05-0.5 mm.

The material of the first current collecting portion 21 and the second current collecting portion 22 is not particularly limited as long as it does not cause chemical changes in a manufactured secondary battery having an electrolyte diffusion promoting function and has high conductivity, and when it is used as a positive electrode current collector, the material may be stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like. In addition, the current collector may be used in any of various forms including a film, a sheet, a foil, a mesh, a porous structure, a foam, and a non-woven fabric. When it is used as a negative electrode current collector, the material thereof may be made of copper, stainless steel, aluminum, nickel, titanium, sintered carbon, copper or stainless steel surface-treated with carbon, nickel, titanium or silver, and aluminum-cadmium alloy. In addition, the current collector may be used in any of various forms including a film, a sheet, a foil, a mesh, a porous structure, a foam, and a non-woven fabric.

In the present application, the connection portion 23 is provided to effectively separate the first collecting portion 21 and the second collecting portion 22, so as to maintain the capacity and shape of the interlayer space 7 relatively stable, and more importantly, the connection portion 23 is provided to effectively increase the rigidity of the collecting portion 2, and the connection portion 23 is not particularly limited in material, can be fixedly connected to the collecting portion and has a certain rigidity, and may have any shape such as a needle shape, a rod shape, a column shape, a long strip shape, a sheet shape, and a cross-sectional shape such as a circle, a star shape, and a polygon shape.

The structure of the connection part 23, which is described in detail below, as the connection part 23 connecting the first collecting part 21 and the second collecting part 22, the connection portion 23 can greatly improve the rigidity of the current collector by fixedly connecting the first current collecting portion 21 and the second current collecting portion 22, the connection portion 23 and the first collecting portion 21 and the second collecting portion 22 may be formed by casting, bonding, welding, or bending, the connection portion 23 may be a connection post 231 and/or a connection bar 232, wherein, the distribution method of the connecting parts 23 in the interlayer space 7 can adopt a regular or irregular distribution mode, the cross section of the connection post 231 may be circular, polygonal, etc., the connection bar 232 is formed in an elongated shape, and the length of the connection bar 232 ranges from 1/4 times to 1 time the width of the collecting portion 2.

The following description is made with reference to fig. 14-18 and 20, respectively: as a specific embodiment, as shown in fig. 14 or 15, the connecting portion 23 is a connecting pillar 231 having a circular cross section, and the connecting pillars 231 are uniformly distributed in the interlayer space 7, and as another embodiment, as shown in fig. 16, the connecting portion 23 includes a connecting bar 232 and a connecting pillar 231, wherein the connecting pillar 231 is uniformly distributed in the middle portion (portion covering the active material) of the interlayer space 7, the connecting bar 232 is two pieces disposed at the outer edges of the left and right sides of the interlayer space 7, and the two connecting bars 232 fixedly connect the left and right sides of the first collecting portion 21 and the second collecting portion 22, respectively. As another embodiment, as shown in fig. 7, the connecting portion 23 is a connecting bar 232, and the connecting bar 232 is uniformly distributed in the length direction of the interlayer space 7. As shown in fig. 18, the connection portions 23 are connection bars 232 with different lengths, the connection bars 232 at the two sides are selected to have the same width as the current collector, and the connection bars at the middle portion may be arranged in an up-and-down crossing manner, so that the electrolyte inside the current collector may better circulate in the length direction of the current collector than the current collector in fig. 17 while the obtained current collector maintains better rigidity. The function of the current collector shown in fig. 20 has been explained above, and will not be described in detail.

As will be described in detail below, the arrangement of the through holes 212 is divided into two non-punched areas 262 and one punched area 261 according to whether or not there are through holes 212 distributed on the active material arrangement surface 26 of the current collecting part 2, the punched area 261 being located at the middle in the longitudinal direction of the current collecting part 2, the non-punched areas 262 being located on both sides of the punched area 261, according to fig. 11; moreover, it is preferable that the above-mentioned design is adopted for both outer surfaces of the flow collecting part 2 to facilitate reduction of the proportion of inactive materials. The punching zone 261 is a rectangular zone, the length L of the punching zone 261₁1/2-4/5 of the length L of the first collecting portion 21.

The through holes 212 may be regularly or irregularly distributed on the surface of the first collecting part 21 or the surface of the second collecting part 22, and the shape of the through holes includes, but is not limited to, a circle, a star, an ellipse, a semicircle, any polygon, and the like, and preferably, the shape is a circle.

As a specific embodiment, in fig. 14-15, a plurality of the through holes 212 are distributed in a rectangular array in the punching zone 261, two rectangular array distributions are shown in fig. 14 and 15, and the distribution shown in fig. 15 is better; similarly, the connecting pillars 231 are arranged in a rectangular array in the interlayer space 7; the through holes 212 are arranged offset from the connection portions 23 in the punching region 261.

As a specific embodiment, the porosity of the current collector C1 ranges from 40% to 80%, it being understood that porosity refers to the percentage of open area and the total area of the current collector coated with active material. If the porosity is too small, the contact area between the portion of the active material close to the surface of the current collector and the electrolyte in the interlayer space 7 is too small, which affects the movement of lithium ions in the active material, and if the porosity is too large, the rigidity of the current collector is insufficient. The inner diameter of the through hole 212 of the first collecting portion 21 or the second collecting portion 22 ranges from 0.001 mm to 10mm, and preferably, the inner diameter of the through hole 212 ranges from 0.05 mm to 0.5 mm.

When the inner diameter of the through hole 212 is smaller, the active material coated on the surface of the through hole is not easy to fall off through the through hole, and the leakage-proof material layer 5 is not required to be added. When the inner diameter of the through hole 212 is set to be larger, the active material on the through hole 212 may be in danger of falling off, and a leakage-proof material layer 5 may be added. The leakage preventing layer 5 may be provided at an inner surface or an outer surface of the first header 21 and/or the second header 22. Sized to cover at least the punched area 261 on current collector C1; the material of the leakage-proof layer 5 may be any material that can allow lithium ions to pass through, and specific choices of the material include, but are not limited to, films, sheets, foils, nets, porous structures, foams, non-woven fabrics, microporous foils or membranes, wherein microporous foils or membranes are preferred.

As a preferred embodiment, as shown in fig. 19, the inner surface of the punched region 261 of the first collecting portion 21 is compounded with the leakage preventing material layer 5, and the inner surface of the punched region 261 of the second collecting portion 22 is compounded with the leakage preventing material layer 5. The advantage of disposing the anti-leakage material layer 5 on the inner surface of the first current collecting portion 21/the second current collecting portion 22 is that the anti-leakage material layer 5 not only can prevent the active material in the through hole 212 from falling off, but also can form a plurality of concave circular grooves on the outer surface of the first current collecting portion 21/the second current collecting portion 22 together with the through hole 212, and the circular grooves can be filled with the active material, so as to reduce the proportion of the inactive material of the electrode, and also can enhance the bonding force between the active material and the first current collecting portion 21/the second current collecting portion 22.

According to some embodiments, as shown in fig. 3,6 or 8, the gap 13 is formed between two adjacent electrodes P1, and the gap 13 is configured to enable the two adjacent electrodes P1 to be filled with the electrolyte, which is different from the way that the adjacent electrodes are configured to be attached to each other in a conventional battery, in which the active material layer is closely attached between two adjacent plates, the battery system is in a liquid-poor state, the electrolyte is diffused between two adjacent plates and inside the active material layer through capillary action, the electrolyte has a poor wetting integrity to the active material, and this poor wetting condition is especially prominent in thick electrodes. This application can make to be full of electrolyte between two liang of adjacent electrodes P1 through setting up of clearance 13 through setting up clearance 13 between two liang of adjacent electrodes P1, and electrolyte can be to the abundant infiltration of active material on the electrode P1, effectively improves the electrolyte and soaks the inhomogeneous problem of reaction interface reactivity that the difference brought with soaking unevenly. In addition, two adjacent electrodes in the traditional electrode assembly are tightly attached through the diaphragm, the thermal conductivity coefficient of the diaphragm is the lowest, due to the existence of the diaphragm, the heat transfer of the battery in the thickness direction of the electrode assembly is very slow, a large amount of heat is collected between the two adjacent electrodes, the gap 13 is arranged to enable the space between the two adjacent electrodes P1 to be filled with electrolyte, the heat of the active material of the electrode P1 can be quickly transferred through the electrolyte between the gap 13, and the electrolyte diffusion device 81 can enable the heat to be quickly diffused into the external electrolyte of the electrode assembly Q1 from the gap 13, so that the heat dissipation problem of the electrode P1 is improved.

Preferably, the height of the gap 13 is in a range that if the height of the gap 13 is too large, the smaller the number of the electrodes P1 arranged in the battery, the smaller the active material occupation ratio is, and the diffusion distance of lithium ions between the positive electrode and the negative electrode is also increased; if the height of the gap 13 is too small, the volume of the electrolyte that can be contained between the adjacent electrodes P1 becomes too small, and concentration polarization becomes severe.

In order to facilitate the installation of the electrode assembly Q1 and control the height of the above gap 13, the secondary battery may further include an insulating frame 62, the structure of the insulating frame 62 being shown in fig. 3 to 4 and 6 to 7, the insulating frame 62 being disposed inside the case 6; and the insulating frame 62 is disposed outside the electrode assembly Q1; the shape of the insulating frame 62 is correspondingly set according to the shape of the electrode assembly Q1, two opposite surfaces of the insulating frame 62 are provided with strip-shaped through holes 621, at least two electrodes P1 are respectively inserted into the strip-shaped through holes 621 of the insulating frame 62, and two ends of the electrode P1 are exposed outside the insulating frame 62. The insulating frame 62 is further provided with a through hole 622 for facilitating the circulation of electrolyte. The insulating frame 62 is preferably made of a material which is light in weight, high in strength, does not act on the electrolyte, and is insulating. A separator (not shown) may be disposed between two adjacent electrodes P1 as needed, and the separator may be fixed using the insulating frame 62.

In order to collect the current of the positive electrode plate P11 and the negative electrode plate P12, the battery further comprises a positive electrode bus bar 63-1 and a negative electrode bus bar 63-2; as shown in fig. 9-10, the bus bar 63 has a first surface 631 and a second surface 632 opposite to each other, the first surface 631 being provided with at least one conductive strip 633 for electrically connecting the current collecting portion 2 of the electrode P1; the second surface 632 is provided with a protruding conductive plate 634, the conductive plate 634 is perpendicular to the second surface 632, the conductive plate 634 is inserted into the sidewall opening 651 of the sidewall 65 of the housing 6, and the conductive plate 634 protrudes outside the housing 6 to form a positive terminal or a negative terminal for conducting current.

In a preferred embodiment, the bus bar 63 is of a rigid structure, and the conductive strip 633 and the current collecting portion 2 are fixedly connected, for example, welded, so that the electrode assembly Q1 and the insulating frame 62 can be fixed inside the casing 6 of the battery B1. In the present application, no force may be directly generated between the insulating frame 62 and the case 6, and the insulating frame 62 is disposed in the cavity 61 by the force of the electrode assembly Q1.

The secondary battery structure with the electrolyte diffusion promoting function is very suitable for being used as a lithium ion battery, and is particularly suitable for the lithium ion battery with the electrolyte injection coefficient of 5.0-20.0; preferably, the lithium ion battery is a lithium iron phosphate battery; and/or the battery is a battery for an energy storage system or a power battery for a vehicle.

The single-sided positive electrode of the battery manufactured by the conventional current collector is generally 60-80 μm thick, and the negative electrode is generally 55-65 μm thick. In this application, its mass flow body C1 has intermediate layer space 7, forms unique lithium ion transportation passageway after through-hole 212 that its surface was seted up communicates with intermediate layer space 7, and lithium ion transportation distance reduces half, consequently, sees from lithium ion diffusion path alone, adopts the mass flow body of this application, can guarantee that each item electrochemical performance of battery does not reduce when active material layer 3 thickness increases to the twice of conventional thickness. Meanwhile, after the current collector is assembled into a battery for use, the interlayer space 7 of the current collector is filled with electrolyte, compared with the barren solution state of the traditional lithium ion battery, the current collector is in a pregnant solution state, various performances of the battery can be further comprehensively improved, finally, the electrode thickness (namely the thickness of the active material layer 3) of the current collector can reach 4-6 times of that of the conventional current collector battery, and tests prove that test data of the battery performance can be obtained when the electrode thickness reaches 6 times of the conventional thickness.

The test is divided into three groups, and batteries are respectively prepared and tested for different multiplying power discharge capacities, energy efficiency and cycle performance data according to the following conditions:

grouping tests:

group A: the thickness of a single-sided positive active material of a traditional current collector, a positive electrode 13um aluminum foil and a negative electrode 8um copper foil is 72.5um, and the negative electrode is 54.0 um;

group B: the thickness of the single-sided positive active material is 435um and 324 um;

group C: use the current collector of this application, wherein:

and (3) positive electrode: a current collector is a 10.2 mm aluminum plate, 60% of round holes are formed, and the diameter of each round hole is 0.5 mm; the current collector is a 20.2 mm aluminum plate, the diameter of each circular hole is 0.5mm, and the distance between the current collectors 1 and 2 is 0.1 mm; the thickness of the single-sided anode active material is 435 um;

negative electrode: a current collector is a copper plate with the diameter of 10.15 mm, 70% of round holes are formed, and the diameter of each round hole is 0.8 mm; a copper plate with the diameter of 20.15 mm and 70% of round holes with the diameter of 0.8mm are arranged, the distance between the current collectors 1 and 2 is 0.1mm), and the coating thickness of the negative active material is 324 um;

the design capacities of the above A, B, C three groups of cells were all 4100mAh, and the detailed design is shown in table 1:

table 1 detailed parameter configuration of three batteries

The three groups of batteries are respectively tested for discharge capacity and charge-discharge energy efficiency under the discharge rate of 0.33-3C, and the results are shown in table 2:

TABLE 2 discharge capacity at different rates and energy efficiency

As can be seen from table 2 above, the discharge capacity and the 1C charge-discharge energy efficiency of the group B at different magnifications are both lower than those of the group a, and the discharge capacity reduction amplitude of the group B at a large magnification tends to increase, and at 0.33C magnification, the discharge capacity is reduced by 6.1% compared with the group a, at 3C magnification, the discharge capacity is reduced by 9.9% compared with the group a, and at 1C magnification, the charge-discharge energy efficiency is reduced by 2.5% compared with the group a; it can be seen that the use of conventional current collectors to fabricate thick electrodes can result in a decrease in the discharge capacity and charge-discharge energy efficiency of the battery.

From the discharge capacity and the 1C charge-discharge energy efficiency under different multiplying powers, the discharge capacity and the 1C charge-discharge energy efficiency of the group C are slightly lower under the multiplying power of 0.33C-1C, and as the multiplying power is increased, the discharge capacity of the group C is higher than that of the group A under the multiplying powers of 2C and 3C, so that the group C and the group A are generally equal and are obviously better than that of the group B from the charge-discharge performance.

In conclusion, under the condition that the coating thickness of the positive/negative electrode active material is the same, compared with the conventional current collector, the discharge capacity and the 1C charge-discharge energy efficiency of the current collector provided by the application can be effectively improved under the multiplying power of 0.33C-3C, the charge-discharge performance of the conventional thin electrode battery is achieved, and the charge-discharge performance of the conventional thin electrode battery is better under the high discharge multiplying power.

The 0.5C/0.5C cycle performance is tested at the temperature of 25 ℃, and the result is shown in FIG. 10, wherein FIG. 10 shows that the capacity retention rate of the B-group battery is reduced rapidly along with the increase of the number of cycles, and the capacity retention rate is 80% when the number of cycles is 461 times; the capacity retention rate of the batteries of the group A and the group C is lower than that of the batteries of the group B along with the increase of the number of cycle turns, and the cycle performance test result of the batteries of the group C is better than that of the batteries of the group A.

Therefore, the B group can enable the battery capacity to be quickly attenuated along with the increase of the cycle number by coating the positive/negative active substances with the conventional current collector in a high thickness, the cycle life of the battery is shortened, and the cycle performance of the battery is not reduced by coating the positive/negative active substances with the current collector 6 times in thickness.

What is not described in this embodiment may be referred to in the relevant description of the rest of the application.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solutions of the present application and not to limit them; although the present application has been described in detail with reference to preferred embodiments, those of ordinary skill in the art will understand that: modifications to the embodiments of the present application or equivalent replacements of some technical features may still be made, which should all be covered by the scope of the technical solution claimed in the present application.

Claims

1. A secondary battery having an electrolyte diffusion promoting function, characterized by comprising:

electrolyte diffusion promoting device for driving the electrolyte to flow.

2. The secondary battery having an electrolyte diffusion promoting function according to claim 1, wherein the electrolyte diffusion promoting means is provided outside the case;

the pipes comprise a first pipe and a second pipe;

3. The secondary battery having an electrolyte diffusion promoting function according to claim 2, wherein the electrodes are divided into positive electrode plates and negative electrode plates according to the polarity of the surface active material, and the positive electrode plates and the negative electrode plates are stacked in the thickness direction of the electrodes in the cavity in a crossed manner.

4. The secondary battery having an electrolyte diffusion promoting function according to claim 3, wherein the electrode comprises a current collector, and an active material layer containing an active material provided on at least one outer surface of the current collector;

wherein the current collector comprises:

an interlayer space configured to accommodate an electrolyte;

5. The secondary battery having an electrolyte diffusion promoting function according to claim 4, wherein the current collecting portion includes:

6. The secondary battery having an electrolyte diffusion promoting function according to claim 5, wherein when the active material layer of the electrode assembly is parallel to the plane of the bottom of the case, the vertical height of the second end of the first tube is higher than that of the first end of the second tube.

7. The secondary battery having an electrolyte diffusion promoting function according to claim 5 or 6, wherein the active material disposing surface is divided into two non-punched regions and a punched region depending on whether or not through-holes are distributed, the punched region being located at a middle portion in a length direction of the current collecting portion, the punched region being flanked by the non-punched regions; the two ends of the short pipe, the second end of the first pipeline and the first end of the second pipeline are arranged in the non-punching area.

8. The secondary battery with the electrolyte diffusion promoting function according to claim 4, wherein a part of the first pipeline, which is located in the cavity, is communicated with a plurality of branch pipelines, the branch pipelines are mutually connected in parallel and arranged on the first pipeline, the number of the branch pipelines is matched with the number of the electrodes in the electrode assembly, and one ends of the branch pipelines, which are far away from the first pipeline, are arranged beside the interlayer space of the electrodes, so that the electrolyte diffusion promoting device can drive the electrolyte in the interlayer space of the electrodes to flow; the first end of the second pipeline is arranged at the top of the cavity.

9. The secondary battery having an electrolyte diffusion promoting function according to claim 4, wherein the active material layer of the electrode assembly is parallel to the plane of the bottom of the case; or the active material layer of the electrode assembly is perpendicular to the plane of the bottom of the case.

10. The secondary battery having an electrolyte diffusion promoting function according to claim 5, wherein the first current collecting portion and the second current collecting portion are arranged in parallel with each other.

11. The secondary battery having an electrolyte diffusion promoting function according to claim 10, wherein the first current collecting portion and the second current collecting portion are each a planar structure.

12. The secondary battery having an electrolyte diffusion promoting function as claimed in claim 10, wherein the first current collecting portion and the second current collecting portion have a rectangular structure having the same size and shape.

13. The secondary battery having an electrolyte diffusion promoting function as claimed in claim 10, wherein the connecting portion is vertically disposed on a plane of the first current collecting portion.

14. The secondary battery having an electrolyte diffusion promoting function according to claim 5, wherein the connecting portion further includes a connecting post.

15. The secondary battery having an electrolyte diffusion promoting function as claimed in claim 14, wherein the connecting pillars are uniformly distributed in the interlayer space.

16. The secondary battery having an electrolyte diffusion promoting function according to claim 1, further comprising an insulating frame disposed inside the case; and the insulating frame is disposed outside the electrode assembly;

17. The secondary battery having an electrolyte diffusion promoting function according to claim 16, further comprising a positive electrode bus bar and a negative electrode bus bar;

18. The secondary battery having an electrolyte diffusion promoting function as claimed in claim 17, wherein the bus bar has a rigid structure, and the bus bar is fixedly connected to the current collecting portion so that the electrode assembly and the insulating frame can be fixed inside the case.

19. The secondary battery having the electrolyte diffusion promoting function as claimed in claim 5, wherein the first current collecting portion and the second current collecting portion are both rigid structures, and the thickness of the first current collecting portion and the thickness of the second current collecting portion are each independently in a range of 0.05-0.5 mm.

20. The secondary battery having an electrolyte diffusion promoting function according to claim 19, wherein the height of the interlayer space has a value in a range of 0.01 to 1 mm.

21. The secondary battery having an electrolyte diffusion promoting function according to claim 4, wherein the thickness of the active material layer has a value in a range of 0.1 to 10 mm.

22. The secondary battery having an electrolyte diffusion promoting function according to claim 21, wherein a thickness of the positive electrode active material layer ranges from 0.1mm to 0.5 mm; and/or the thickness of the negative active material layer ranges from 0.1mm to 0.4 mm.

23. The secondary battery having an electrolyte diffusion promoting function according to claim 1, wherein the battery is a lithium ion battery.

24. The secondary battery having an electrolyte diffusion promoting function as claimed in claim 23, wherein the lithium ion battery has a liquid injection coefficient of 5.0 to 20.0.

25. The secondary battery having an electrolyte diffusion-promoting function according to claim 24, wherein the lithium ion battery is a lithium iron phosphate battery; and/or the battery is a battery for an energy storage system or a power battery for a vehicle.