CN216818412U

CN216818412U - Battery cell structure

Info

Publication number: CN216818412U
Application number: CN202122457763.7U
Authority: CN
Inventors: 吴聪苗; 曾海师; 唐潘; 张宁辉; 朱有治
Original assignee: Xiamen Haichen New Energy Technology Co Ltd
Current assignee: Xiamen Hithium Energy Storage Technology Co Ltd
Priority date: 2021-10-12
Filing date: 2021-10-12
Publication date: 2022-06-24
Anticipated expiration: 2031-10-12

Abstract

The application provides a battery cell structure, and relates to the technical field of batteries. The battery cell structure comprises positive pole pieces and negative pole pieces which are alternately arranged. The positive pole piece comprises a positive insulating layer, a first conducting layer and a second conducting layer which are arranged on the surface of the positive insulating layer, a first positive active material layer arranged on the surface of the first conducting layer, and a second positive active material layer arranged on the surface of the second conducting layer; the negative pole piece comprises a negative pole insulating layer, a third conducting layer and a fourth conducting layer which are arranged on the surface of the negative pole insulating layer, a first negative pole active material layer arranged on the surface of the third conducting layer, and a second negative pole active material layer arranged on the surface of the fourth conducting layer; the adjacent positive pole piece and the negative pole piece are separated by an isolating film, and the currents of the first conducting layer and the second conducting layer of the positive pole piece are respectively led out through the first lug and the second lug; and the currents of the third conducting layer and the fourth conducting layer of the negative pole piece are respectively led out through the third lug and the fourth lug. Which can improve the performance defect of the lithium battery.

Description

Battery cell structure

Technical Field

The application relates to the technical field of batteries, in particular to an electric core structure.

Background

At present, in a common lithium battery structure, aluminum foil and copper foil are generally used as a positive electrode and a negative electrode, and the battery performance of the lithium battery is easy to cause defects.

SUMMERY OF THE UTILITY MODEL

An object of the embodiment of this application is to provide a battery cell structure, it can improve the performance defect of prior art's lithium cell.

The embodiment of the application is realized as follows:

an embodiment of the present application provides an electricity core structure, includes: the positive pole piece and the negative pole piece are alternately arranged;

the positive pole piece comprises a positive pole insulating layer, a first conducting layer and a second conducting layer on two surfaces of the positive pole insulating layer, a first positive pole active material layer on the surface of the first conducting layer, and a second positive pole active material layer on the surface of the second conducting layer;

the negative pole piece comprises a negative pole insulating layer, a third conducting layer and a fourth conducting layer on two surfaces of the negative pole insulating layer, a first negative pole active material layer on the surface of the third conducting layer and a second negative pole active material layer on the surface of the fourth conducting layer;

the adjacent positive pole piece and the negative pole piece are separated by an isolating membrane;

the currents of the first conducting layer and the second conducting layer of the positive pole piece are respectively led out through the first pole lug and the second pole lug;

and the currents of the third conducting layer and the fourth conducting layer of the negative pole piece are respectively led out through the third lug and the fourth lug.

The beneficial effect of the electric core structure of this application embodiment includes:

the battery cell structure comprises positive pole pieces and negative pole pieces which are alternately arranged, the positive pole pieces and the negative pole pieces which are adjacently arranged are separated through an isolating membrane, then in the process of charging and discharging the battery, any one of a first positive active material layer and a second positive active material layer, any one of a first negative active material layer and a second negative active material layer and the isolating membrane can form a lithium ion battery, the formed lithium ion battery can be isolated due to the existence of a positive insulating layer and a negative insulating layer, the current of the first conducting layer and the current of the second conducting layer are respectively led out through a first lug and a second lug, the current of the third conducting layer and the current of the fourth conducting layer are respectively led out through a third lug and a fourth lug, so that the whole battery cell structure can be regarded as a plurality of independent lithium ion batteries, and the plurality of independent lithium ion batteries have no common current collector, the plurality of individual lithium ion batteries together determine the performance of the overall cell structure. By designing the performance of a plurality of independent lithium ion batteries, the performance defects of the lithium batteries can be overcome.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a cross-sectional view of a cell structure according to an embodiment of the present disclosure;

fig. 2 is a tab arrangement manner of a first cell structure according to an embodiment of the present disclosure;

fig. 3 is a tab arrangement manner of a second cell structure according to an embodiment of the present disclosure;

fig. 4 is a tab arrangement manner of a third cell structure according to an embodiment of the present disclosure;

fig. 5 is a fourth tab arrangement manner of the cell structure according to the embodiment of the present application;

fig. 6 is a fifth tab arrangement manner of a cell structure according to an embodiment of the present application;

fig. 7 is a tab arrangement manner of a sixth cell structure according to the embodiment of the present application;

fig. 8 is a tab arrangement manner of a seventh cell structure according to the embodiment of the present application;

fig. 9 is a cross-sectional view of another cell structure according to an embodiment of the present application;

fig. 10 is an eighth tab arrangement manner of a cell structure according to an embodiment of the present application;

fig. 11 is a ninth tab arrangement manner of a cell structure according to an embodiment of the present application.

Icon: 10-cell structure; 11-positive pole piece; 111-positive electrode insulating layer; 112-a first conductive layer; 113-a second conductive layer; 114 — a first positive electrode active material layer; 115-a second positive active material layer; 12-a negative pole piece; 121-negative electrode insulating layer; 122-a third conductive layer; 123-a fourth conductive layer; 124-a first negative active material layer; 125-a second negative active material layer; 13-a first barrier film; 14-a second barrier film; 151-a first tab; 152-a second tab; 153-a third tab; 154-a fourth tab; 16-plane of symmetry of the winding.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, 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 some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, as presented in the figures, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. 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.

In addition, those whose specific conditions are not specified in the examples are conducted under the conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Scheme a and/or scheme B refers to scheme a or scheme B, or a combination of scheme a and scheme B.

The following specifically describes the cell structure 10 according to the embodiment of the present application:

the embodiment of the present application provides a cell structure 10, which includes positive electrode tabs 11 and negative electrode tabs 12 that are alternately arranged (refer to fig. 1 and 9). The cell structure 10 may be a winding structure or a lamination structure.

The positive electrode tab 11 includes a positive electrode insulating layer 111, a first conductive layer 112 and a second conductive layer 113 on both surfaces of the positive electrode insulating layer 111, a first positive electrode active material layer 114 on a surface of the first conductive layer 112, and a second positive electrode active material layer 115 on a surface of the second conductive layer 113.

The negative electrode tab 12 includes a negative electrode insulating layer 121, a third conductive layer 122 and a fourth conductive layer 123 on both surfaces of the negative electrode insulating layer 121, a first negative electrode active material layer 124 on a surface of the third conductive layer 122, and a second negative electrode active material layer 125 on a surface of the fourth conductive layer 123.

The adjacent positive pole piece 11 and the negative pole piece 12 are separated by a separation film.

The currents of the first conductive layer 112 and the second conductive layer 113 of the positive electrode tab 11 are respectively led out through the first tab 151 and the second tab 152.

The currents of the third conductive layer 122 and the fourth conductive layer 123 of the negative electrode tab 12 are respectively led out through the third tab 153 and the fourth tab 154.

The cell structure 10 includes positive electrode plates 11 and negative electrode plates 12 alternately arranged, the positive electrode plates 11 and the negative electrode plates 12 adjacently arranged are separated by a separation film, then in the process of charging and discharging the battery, any one of the first positive active material layer 114 and the second positive active material layer 115, any one of the first negative active material layer 124 and the second negative active material layer 125, and the separation film can constitute a lithium ion battery, due to the existence of the positive insulating layer 111 and the negative insulating layer 121, the constituted lithium ion battery can be separated, the currents of the first conductive layer 112 and the second conductive layer 113 are respectively led out through the first tab 151 and the second tab 152, and the currents of the third conductive layer 122 and the fourth conductive layer 123 are respectively led out through the third tab 153 and the fourth tab 154, so that the whole cell structure 10 can be regarded as a plurality of independent lithium ion batteries, a plurality of individual lithium ion batteries, which collectively determine the performance of the overall cell structure 10, do not share a common current collector. By designing the performance of a plurality of independent lithium ion batteries, the performance defects of the lithium batteries can be overcome.

The first tab 151, the second tab 152, the third tab 153, and the fourth tab 154 correspond to only one conductive layer, and the tabs at the same position all correspond to the same conductive layer, for example, the first tab 151, the second tab 152, the third tab 153, and the fourth tab 154 may be provided in plural numbers, and the tabs at the same position are connected by welding or other connection methods, so that the electricity of the plurality of first conductive layers 112, the plurality of second conductive layers 113, the plurality of third conductive layers 122, and the plurality of fourth conductive layers 123 can be collected, the first conductive layers 112, the second conductive layers 113, the third conductive layers 122, and the fourth conductive layers 123 do not interfere with each other in the tab collecting process, and two independent lithium ion batteries can be completely separated.

For example, the first positive electrode active material layer 114 and the first negative electrode active material layer 124 and the separator may constitute one independent lithium ion battery, the second positive electrode active material layer 115 and the second negative electrode active material layer 125 may constitute one independent lithium ion battery, the first positive electrode active material layer 114 and the second negative electrode active material layer 125 may constitute one independent lithium ion battery, and the second positive electrode active material layer 115 and the first negative electrode active material layer 124 may constitute one independent lithium ion battery. The whole cell structure 10 may form at least two of the batteries according to different arrangement and combination modes of the positive electrode plate and the negative electrode plate.

Illustratively, the adjacently disposed first anode active material layer 124 and first cathode active material layer 114 are separated by a first separator 13, and the adjacently disposed second cathode active material layer 115 and second anode active material layer 125 are separated by a second separator 14. In the cell structure 10, a first positive electrode active material layer 114, a first conductive layer 112, a positive electrode insulating layer 111, a second conductive layer 113, a second positive electrode active material layer 115, a second separator 14, a second negative electrode active material layer 125, a fourth conductive layer 123, a negative electrode insulating layer 121, a third conductive layer 122, a first negative electrode active material layer 124, and a first separator 13 are sequentially and cyclically stacked.

In another embodiment, the first positive electrode active material layer 114, the first conductive layer 112, the positive electrode insulating layer 111, the second conductive layer 113, the second positive electrode active material layer 115, the separator, the first negative electrode active material layer 124, the third conductive layer 122, the negative electrode insulating layer 121, the fourth conductive layer 123, the second negative electrode active material layer 125, and the separator may be cyclically stacked in this order.

Illustratively, the capacity ratio of any one of the first and second anode

active material layers

124 and 125 to any one of the first and second cathode

active material layers

114 and 115 is 1.07 to 1.2, so that lithium ions can move from the cathode to the anode of the lithium ion battery without causing lithium precipitation. Wherein, the capacity ratio can be called CB value or NP ratio. Illustratively, the capacity ratio is 1.07, 1.08, 1.09, 1.1, 1.12, 1.14, 1.15, 1.16, 1.18, or 1.2.

In one possible embodiment, the first conductive layer 112 and the second conductive layer 113 of the positive electrode tab 11 are disposed at the tab in a staggered manner, the first conductive layer 112 and the positive electrode insulating layer 111 extend outward relative to the second conductive layer to form a first tab 151, and the second conductive layer 113 and the positive electrode insulating layer 111 extend outward relative to the first conductive layer 112 to form a second tab 152.

The third conductive layer 122 and the fourth conductive layer 123 of the negative electrode tab 12 are disposed at the tab position in a staggered manner, the third conductive layer 122 and the negative electrode insulating layer 121 extend outward relative to the fourth conductive layer 123 to form a third tab 153, and the fourth conductive layer 123 and the negative electrode insulating layer 121 extend outward relative to the fourth conductive layer 123 to form a fourth tab 154.

In other embodiments, the first tab 151 may be welded to the first conductive layer 112, the second tab 152 may be welded to the second conductive layer 113, the third tab 153 may be welded to the third conductive layer 122, and the fourth tab 154 may be welded to the fourth conductive layer 123, so as to respectively draw out the current of the first conductive layer 112, the second conductive layer 113, the third conductive layer 122, and the fourth conductive layer 123.

Taking the following cell structure as an example, referring to fig. 1, a first negative electrode active material layer 124 and a first positive electrode active material layer 114 which are adjacently disposed are separated by a first separator 13, and a second positive electrode active material layer 115 and a second negative electrode active material layer 125 which are adjacently disposed are separated by a second separator 14.

When the cell structure 10 is a wound structure or a laminated structure, the first tab 151, the second tab 152, the third tab 153, and the fourth tab 154 may be disposed on the same side in the height direction of the cell structure 10 (see fig. 1 to 8), or may be disposed on both sides in the height direction of the cell structure 10 (see fig. 9 to 11).

When the cell structure 10 is a winding structure, and the first tab 151, the second tab 152, the third tab 153 and the fourth tab 154 are disposed on the same side of the height direction of the cell structure 10, the arrangement of the tabs is also various, and the arrangement thereof is further described below, and the arrangement thereof includes:

(1) referring to fig. 2, the first tab 151 and the fourth tab 154 are disposed at one side of the winding symmetry plane 16 of the winding structure, and the second tab 152 and the third tab 153 are distributed at the other side of the winding symmetry plane 16 of the winding structure; the first tab 151 is disposed between the second tab 152 and the third tab 153 in the length direction of the winding structure.

(2) Referring to fig. 3, the second tab 152 and the third tab 153 are distributed on one side of the winding symmetry plane 16 of the winding structure, and the first tab 151 and the fourth tab 154 are distributed on the other side of the winding symmetry plane 16 of the winding structure; in the length direction of the coiled structure, a fourth tab 154 is disposed between the second tab 152 and the third tab 153.

(3) Referring to fig. 4, the first tab 151 and the second tab 152 are distributed on one side of the winding symmetry plane 16 of the winding structure, and the third tab 153 and the fourth tab 154 are distributed on the other side of the winding symmetry plane 16 of the winding structure; the third tab 153 is disposed between the first tab 151 and the second tab 152 in a length direction of the winding structure.

(4) Referring to fig. 5, the first tab 151 and the second tab 152 are distributed on one side of the winding symmetry plane 16 of the winding structure, the third tab 153 and the fourth tab 154 are distributed on the other side of the winding symmetry plane 16 of the winding structure, and the first tab 151 and the third tab 153 are distributed on both sides of the winding symmetry plane 16 of the winding structure; the first tab 151 is disposed between the second tab 152 and the third tab 153 in the length direction of the winding structure.

(5) Referring to fig. 6, the first tab 151, the second tab 152, the third tab 153, and the fourth tab 154 are disposed on the same side of the winding symmetry plane 16 of the winding structure.

(6) Referring to fig. 7, a first tab 151, a second tab 152, a third tab 153, and a fourth tab 154 are formed on both sides of a winding symmetry plane 16 of a winding structure.

When the cell structure 10 is a winding structure, and the first tab 151, the second tab 152, the third tab 153, and the fourth tab 154 are distributed on two opposite sides of the cell structure 10 in the height direction, the arrangement of the tabs is exemplarily similar to the above-mentioned (1) - (4), except that in the (1) - (4) modes, the tab on one side of the winding symmetry plane 16 of the winding structure and the tab on the other side of the winding symmetry plane 16 of the winding structure are distributed on two sides of the winding structure in the height direction.

When the cell structure 10 is a laminated structure, the arrangement mode of the tabs is described as follows:

when the cell structure 10 is a laminated sheet, the first tab 151, the second tab 152, the third tab 153, and the fourth tab 154 may be disposed on the same side in the height direction of the cell structure 10 (see fig. 8), or may be distributed on both sides in the height direction of the cell structure 10 (see fig. 10 to 11).

Further, the first positive electrode active material layer 114 and the second positive electrode active material layer 115 are different, and/or the first negative electrode active material layer 124 and the second negative electrode active material layer 125 are different. That is, the first positive electrode active material layer 114 and the second positive electrode active material layer 115 may be different, while the first negative electrode active material layer 124 and the second negative electrode active material layer 125 may be different, or the first positive electrode active material layer 114 and the second positive electrode active material layer 115 may be different or the first negative electrode active material layer 124 and the second negative electrode active material layer 125 may be different. The arrangement makes a plurality of independent lithium ion batteries different, and the performance defects of the lithium battery with a single active material can be improved by designing the performance of the plurality of independent and different lithium ion batteries.

The first positive electrode active material layer 114 and the second positive electrode active material layer 115 may be different in the kind of active material of the first positive electrode active material layer 114 and the second positive electrode active material layer 115, or may be different in the particle diameter, specific surface area, gram volume, and the like, with the same kind of active material of the first positive electrode active material layer 114 and the second positive electrode active material layer 115. It is understood that the first positive electrode active material layer 114 and the second positive electrode active material layer 115 may contain a binder, a conductive agent, or the like, in addition to the active material.

Regardless of whether the types of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 are the same or different, the active material of the first positive electrode active material layer 114 may be selected from lithium iron phosphate, single crystal lithium nickel cobalt manganese oxide, polycrystalline lithium nickel cobalt manganese oxide, lithium titanate, lithium manganate, or lithium cobaltate, and the active material of the second positive electrode active material layer 115 may also be selected from lithium iron phosphate, single crystal lithium nickel cobalt manganese oxide, polycrystalline lithium nickel cobalt manganese oxide, lithium titanate, lithium manganate, or lithium cobaltate.

Optionally, the lithium iron phosphate of the embodiment of the present application has a D10 particle size>0.4μm，DThe particle size of 50 is 0.8 to 4 μm, and the particle size of D90 is 3 to 10 μm. The specific surface area of the lithium iron phosphate is 8-16 m²The gram capacity is 100-160 mAh/g. Optionally, the compacted density of the lithium iron phosphate is 2.1-2.6 g/cm³The granule matching is better.

Optionally, the grain size of D10 of single crystal lithium nickel cobalt manganese oxide in the embodiment of the present application>1.5 μm, D50 particle size of 4-10 μm, and D90 particle size of 9-20 μm. The specific surface area of the monocrystal nickel cobalt lithium manganate is 0.3-0.6 m²The gram capacity is 160-210 mAh/g. Optionally, the coating amount of the single-crystal nickel cobalt lithium manganate is 10-26 mg/cm². Optionally, the compaction density of the single crystal nickel cobalt lithium manganate is 3.2-3.75 g/cm³。

Optionally, the grain size of D10 of polycrystalline nickel cobalt lithium manganate in the embodiment of the present application>1.5 μm, D50 particle size of 8-12 μm, and D90 particle size of 18-34 μm. The specific surface area of the polycrystalline nickel cobalt lithium manganate is 0.2-0.6 m²And the gram capacity of the polycrystalline nickel cobalt lithium manganate is 165-211 mAh/g. Optionally, the coating amount of the single-crystal nickel cobalt lithium manganate is 10-26 mg/cm². Optionally, the compaction density of the polycrystalline nickel cobalt lithium manganate is 3.2-3.6 g/cm³。

Illustratively, when the active materials of the first and second positive electrode active material layers 114 and 115 are lithium iron phosphate, single-crystal lithium nickel cobalt manganese oxide, polycrystalline lithium nickel cobalt manganese oxide, the coating amount of the lithium iron phosphate is 5 to 22mg/cm²The coating amount of the monocrystal nickel cobalt lithium manganate is 10-26 mg/cm²The coating amount of the polycrystalline nickel cobalt lithium manganate is 10-26 mg/cm²。

The larger the coating amount of the active material of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 is, the less likely to dry, the lower the coating efficiency, and the more likely to crack. The coating amount is large, the DCR is large, the polarization is large, the capacity exertion is not facilitated, and the heating of the battery core is large. But a large amount of coating can increase the energy density. If the coating amount is small and the thickness is thin, the shorter the path for ions to migrate into the internal active material, which is advantageous for increasing the rate. The coating amounts of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 are suitable, which is beneficial for the electrical core structure 10 to have better comprehensive performanceAnd (4) performance. Illustratively, the coating amount of lithium iron phosphate is 5mg/cm²、8mg/cm²、10mg/cm²、12mg/cm²、15mg/cm²、18mg/cm²Or 22mg/cm². Illustratively, the coating amount of the single-crystal lithium nickel cobalt manganese oxide and the polycrystalline lithium nickel cobalt manganese oxide is 10mg/cm²、12mg/cm²、15mg/cm²、18mg/cm²、22mg/cm²Or 26mg/cm²。

Illustratively, the first positive electrode active material layer 114 and the second positive electrode active material layer 115 differently include: the kind of the active material of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 is the same, and any one or more of the following schemes:

in one possible embodiment, the particle size of D10 of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 is different by 0.05-0.3 μm, the particle size of D50 is different by 1-4 μm, and the particle size of D90 is different by 3-5 μm.

In the present embodiment, the D10 particle size refers to a particle size having a cumulative particle distribution of 10%, the D50 particle size refers to a particle size having a cumulative particle distribution of 50%, and the D90 particle size refers to a particle size having a cumulative particle distribution of 90%.

The active material with large particle size has a long ion migration path but a low magnification, the active material with small particle size has a high magnification, dead zones are not easily formed in the particles, the cycle life is long, and the defect of the low magnification of the ion battery formed by the positive active material layers of the active material with large particle size can be overcome by arranging the active materials of the first positive active material layer 114 and the second positive active material layer 115 with the particle size difference of D10 of 0.05-0.3 mu m, the particle size difference of D50 of 1-4 mu m, the particle size difference of D90 of 3-5 mu m and the positive active material layer of the positive active material with small particle size. In addition, the first positive electrode active material layer 114 and the second positive electrode active material layer 115 each use an active material having a different particle diameter range, and the tap density can be increased.

In the embodiment of the present application, the particle size of the active material of the first positive electrode active material layer 114 may be larger than the particle size of the active material of the second positive electrode active material layer 115, or the particle size of the active material of the second positive electrode active material layer 115 may be larger than the particle size of the active material of the first positive electrode active material layer 114, as long as the particle size of D10, the particle size of D50, and the particle size of D90 of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 are different by 0.05 to 0.3 μm, 1 to 4 μm, and 3 to 5 μm.

Alternatively, the D10 particle sizes of the active materials of the first and second positive electrode active material layers 114 and 115 differ by 0.05 μm, 0.08 μm, 0.1 μm, 0.2 μm, or 0.3 μm.

Alternatively, the D50 particle diameters of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 differ by 1 μm, 2 μm, 3 μm, or 4 μm. Alternatively, the D90 particle sizes of the active materials of the first and second positive electrode active material layers 114 and 115 differ by 3 μm, 4 μm, or 5 μm.

In one possible embodiment, the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 are both lithium iron phosphate, part or all of the surface of the lithium iron phosphate is coated with a carbon coating layer, and the carbon coating amount of the lithium iron phosphate of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 is different by more than or equal to 0.1%, wherein the carbon coating amount is the ratio of the weight of the carbon coating layer to the weight of the carbon coating layer and the lithium iron phosphate.

The surface of the lithium iron phosphate is coated with carbon, so that the conductivity of the active materials of the first positive active material layer 114 and the second positive active material layer 115 can be improved, the electronic conductivity is improved, the multiplying power is good, and the overall electrical property of the battery structure is good. The difference between the carbon coating amounts of the lithium iron phosphate of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 is not less than 0.1%, and the difference between the carbon coating amounts of the lithium iron phosphate of the first positive electrode active material layer and the carbon coating amounts of the lithium iron phosphate of the second positive electrode active material layer can be fully ensured. In the embodiment of the present application, the carbon coating amount of the lithium iron phosphate in the first positive electrode active material layer 114 may be greater than the carbon coating amount of the lithium iron phosphate in the second positive electrode active material layer 115, or the carbon coating amount of the lithium iron phosphate in the second positive electrode active material layer 115 may be greater than the carbon coating amount of the lithium iron phosphate in the first positive electrode active material layer 114.

Optionally, the weight of the carbon coating layer is 0.8-1.6%, for example, 0.8%, 0.9%, 1.0%, 1.2%, 1.4%, 1.5%, or 1.6% of the total weight of the carbon coating layer and the lithium iron phosphate.

In one possible embodiment, the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 have a difference of 0.1 to 8m in specific surface area²/g。

The specific surface area of the particles is the total surface/total mass of the particles, and the specific surface area of the particles is large, the corresponding particle size is small, and ions have more entry paths, so the rate is good. However, the SEI film has a large specific surface area, consumes more lithium ions, and has low first efficiency. In the embodiment of the application, the difference of the specific surface areas of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 is 0.1-8 m²The specific surface area of the active material layer of the active material with small specific surface area is larger than that of the active material layer of the active material with large specific surface area, and the specific surface area of the active material layer is larger than that of the active material layer of the active material. In the present embodiment, the specific surface area of the first positive electrode active material layer 114 may be larger than the specific surface area of the active material of the second positive electrode active material layer 115, or the specific surface area of the active material of the second positive electrode active material layer 115 may be larger than the specific surface area of the active material of the first positive electrode active material layer 114.

Illustratively, the specific surface areas of the active materials of the first and second positive electrode active material layers 114 and 115 differ by 0.1m²/g、0.5m²/g、1m²/g、2m²/g、3m²/g、4m²/g、5m²/g、6m²/g、7m²G or 8m²/g。

In one possible embodiment, the gram capacities of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 differ by 10 to 60 mAh/g.

The high gram volume of the active substance can reduce the coating thickness, thereby reducing the process difficulty and improving the energy density. If the gram volume of the active material of the same material is small, the coating thickness needs to be increased, and the energy density of the battery is low, but the cost is generally low. In the embodiment of the application, the gram-capacity difference between the active materials of the first positive active material layer 114 and the second positive active material layer 115 is 10-60 mAh/g, so that the difference between the two lithium ion batteries can be ensured, the performance of the lithium ion battery consisting of the positive active material layer of the active material with small gram-capacity and the performance of the lithium ion battery consisting of the positive active material layer of the active material with large gram-capacity can be complemented, and the whole battery structure has high discharge rate, high initial energy density and proper cost. In the present embodiment, the gram capacity of the first positive electrode active material layer 114 may be larger than the gram capacity of the active material of the second positive electrode active material layer 115, or the gram capacity of the second positive electrode active material layer 115 may be larger than the gram capacity of the active material of the first positive electrode active material layer 114.

Illustratively, the gram capacities of the active materials of the first and second positive active material layers 114 and 115 differ by 10mAh/g, 20mAh/g, 30mAh/g, 40mAh/g, 50mAh/g, or 60 mAh/g.

Alternatively, the compacted densities of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 differ by 0.02g/cm or more³For example, 0.02g/cm³、0.04g/cm³、0.06g/cm³、0.08g/cm³、0.10g/cm³、0.15g/cm³、0.20g/cm³。

In one possible embodiment, the difference in thickness between the first conductive layer 112 and the second conductive layer 113 is 0.1 to 1 μm, for example 0.1 μm, 0.3 μm, 0.5 μm, 0.8 μm or 1 μm. The first conductive layer 112 and the second conductive layer 113 have a thickness of 0.1 to 3 μm, for example, 0.1 μm, 0.5 μm, 1 μm, 2 μm, or 3 μm.

In one possible embodiment, the difference in thickness between the first positive electrode active material layer 114 and the second positive electrode active material layer 115 is 5 to 50 μm, for example, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, or 50 μm.

The thicknesses of the first conductive layer 112, the second conductive layer 113, the first cathode active material layer 114, and the second cathode active material layer 115 may affect the difficulty of the process, and if the thicknesses are too thick, drying is not easy, coating efficiency is low, and cracks are easily generated. The first conducting layer, the second conducting layer, the first positive active material layer 114 and the second positive active material layer 115 are appropriate in thickness, the path for ions to migrate into the internal active material is short, polarization is small, multiplying power charge and discharge are facilitated, DCR is small, and cycle performance is good.

When the types of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 are different, the difference between the first positive electrode active material layer 114 and the second positive electrode active material layer 115 may be ensured by any one or more of the following schemes.

Illustratively, the active material of the first positive electrode active material layer 114 is lithium iron phosphate, and the active material of the second positive electrode active material layer 115 is single-crystal lithium nickel cobalt manganese oxide. Illustratively, the active material of the first positive electrode active material layer 114 is lithium iron phosphate, and the active material of the second positive electrode active material layer 115 is polycrystalline lithium nickel cobalt manganese oxide. Illustratively, the active material of the first positive electrode active material layer 114 is single crystal lithium nickel cobalt manganese oxide, and the active material of the second positive electrode active material layer 115 is lithium iron phosphate. Illustratively, the active material of the first positive electrode active material layer 114 is single-crystal lithium nickel cobalt manganese oxide, and the active material of the second positive electrode active material layer 115 is polycrystalline lithium nickel cobalt manganese oxide. Illustratively, the active material of the first positive electrode active material layer 114 is polycrystalline lithium nickel cobalt manganese oxide, and the active material of the second positive electrode active material layer 115 is single crystalline lithium nickel cobalt manganese oxide. Illustratively, the active material of the first positive electrode active material layer 114 is polycrystalline lithium nickel cobalt manganese oxide, the active material of the second positive electrode active material layer 115 is illustratively, the active material of the first positive electrode active material layer 114 is polycrystalline lithium nickel cobalt manganese oxide, and the active material of the second positive electrode active material layer 115 is single crystalline lithium nickel cobalt manganese oxide.

In one possible embodiment, the particle size of D10 of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 is different by 1 to 3 μm, the particle size of D50 is different by 2 to 5 μm, and the particle size of D90 is different by 3 to 25 μm.

The active material with large particle size has long ion migration path but low multiplying power, the active material with small particle size has good multiplying power, dead zones are not easy to form in the particles, and the cycle life is long. Under the condition that the types of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 are different, the difference of the particle diameters of the active materials of D10, D50, D90 and D90 of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 is 1-3 mu m, 2-5 mu m and 3-25 mu m, and the difference of the particle diameters of the active materials with small particle diameters is set, so that the defect of the difference of the magnification of the ion battery composed of the positive electrode active material layers of the active materials with large particle diameters can be improved. In the present embodiment, the particle diameter of the active material of the first positive electrode active material layer 114 may be larger than the particle diameter of the active material of the second positive electrode active material layer 115, or the particle diameter of the active material of the second positive electrode active material layer 115 may be larger than the particle diameter of the active material of the first positive electrode active material layer 114.

Illustratively, the D10 particle sizes of the active materials of the first and second positive electrode active material layers 114 and 115 differ by 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3 μm.

Illustratively, the D50 particle sizes of the active materials of the first and second positive electrode active material layers 114 and 115 differ by 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, or 5 μm.

Illustratively, the D90 particle sizes of the active materials of the first and second positive electrode active material layers 114 and 115 differ by 3 μm, 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 20 μm, or 25 μm.

In one possible embodiment, the difference between the specific surface areas of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 is 7-15 m²/g。

The specific surface area of the particles is large, the corresponding particle size is small, and ions have more entering paths, so the multiplying power is good. But has a large specific surface area and forms SThe EI film consumes more lithium ions and is inefficient for the first time. In the embodiment, when the types of active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 are different, the specific surface areas of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 are different by 7-15 m²The specific surface area of the active material layer of the active material with small specific surface area is larger than that of the active material layer of the active material with large specific surface area, and the specific surface area of the active material layer is larger than that of the active material layer of the active material.

Illustratively, the specific surface areas of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 differ by 7m²/g、8m²/g、9m²/g、10m²/g、11m²/g、12m²/g、13m²/g、14m²G or 15m²/g。

In one possible embodiment, the gram capacities of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 differ by 20 to 110 mAh/g.

In the embodiment of the application, under the condition that the types of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 are different, the difference between the gram capacities of the active materials of the first positive electrode active material layer 114 and the second positive electrode active material layer 115 is 20-110 mAh/g, so that not only can two different lithium ion batteries be ensured, but also the performance of the lithium ion battery composed of the positive electrode active material layer of the active material with small gram capacity and the performance of the lithium ion battery composed of the positive electrode active material layer of the active material with large gram capacity can be complemented, and the whole battery structure has both higher discharge rate and higher energy density.

Illustratively, the gram capacities of the active materials of the first and second positive active material layers 114 and 115 differ by 20mAh/g, 30mAh/g, 40mAh/g, 50mAh/g, 60mAh/g, 70mAh/g, 80mAh/g, 90mAh/g, 100mAh/g, or 110 mAh/g.

First positive electrode activityThe difference between the compacted densities of the material layer 114 and the second positive electrode active material layer 115 is not less than 0.8g/cm³For example, 0.8g/cm³、1g/cm³、1.5g/cm³Or 2g/cm³。

In one possible embodiment, the difference in thickness between the first conductive layer 112 and the second conductive layer 113 is 0.1 to 1.8 μm, such as 0.1 μm, 0.3 μm, 0.5 μm, 0.8 μm, 1 μm, 1.5 μm, or 1.8 μm. In one possible embodiment, the difference in thickness between the first positive electrode active material layer 114 and the second positive electrode active material layer 115 is 5 to 50 μm, for example, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, or 50 μm.

The first conductive layer 112 and the second conductive layer 113 have a thickness of 0.1 to 3 μm, for example, 0.1 μm, 0.5 μm, 1 μm, 2 μm, or 3 μm.

The thicknesses of the first conductive layer 112, the second conductive layer 113, the first cathode active material layer 114, and the second cathode active material layer 115 may affect the difficulty of the process, and if the thicknesses are too thick, drying is not easy, coating efficiency is low, and cracks are easily generated. The first conducting layer, the second conducting layer, the first positive active material layer 114 and the second positive active material layer 115 are appropriate in thickness, the path for ions to migrate into the internal active material is short, polarization is small, multiplying power charging and discharging are facilitated, DCR is small, and cycle performance is good.

The first negative electrode active material layer 124 and the second negative electrode active material layer 125 of the embodiments of the present application are not specifically described below.

When the first active cathode material and the second cathode active material layer 115 are different, the first anode active material layer 124 and the second anode active material layer 125 may be the same or different. When the first anode active material layers 124 are different, the types of active materials of the first anode active material layers 124 may be different, or the types of active materials of the first anode active material layers 124 may be the same, but the particle diameter, specific surface area, gram capacity, and the like are different.

Regardless of whether the kinds of active materials of the first and second anode active material layers 124 and 125 are the same or different, the active material of the first anode active material layer 124 is selected from graphite, silicon carbon, or mesocarbon microbeads, and the active material of the second anode active material layer 125 is also selected from graphite, silicon carbon, or mesocarbon microbeads.

Alternatively, the D10 particle size of the graphite of the examples herein>4 mu m, the D50 particle size is 7-15 mu m, and the D90 particle size is less than or equal to 30 mu m. Optionally, the specific surface area of the graphite is 0.5-8 m²G, gram volume of 250-360 mAh/g, and coating amount of 5-15 mg/cm²The compaction density is 1.1-1.8 g/cm³。

Optionally, the grain size of D10 of the silicon carbon in the embodiments of the present application is 1 to 4 μm, the grain size of D50 is 4 to 8 μm, and the grain size of D90 is 9 to 12 μm. Optionally, the specific surface area of the silicon carbon is 0.5-8 m²G, gram volume of 360-1000 mAh/g, and coating amount of 5-10 mg/cm²The compaction density is 1.1-2 g/cm³。

Optionally, the mesocarbon microbeads of the examples herein have a D10 particle size>4 μm, the D50 particle size is 7-15 μm, and the D90 particle size is less than or equal to 30 μm. Optionally, the specific surface area of the mesocarbon microbeads is 0.5-4 m²A gram volume of 200-400 mAh/g, and a coating amount of 5-10 mg/cm²The compaction density is 1-2 g/cm³。

Illustratively, when the kinds of the active materials of the first and second anode active material layers 124 and 125 are the same, the particle diameters of D10, D50, and D90 of the active materials of the first and second anode active material layers 124 and 125 are different by 0.1 to 4 μm, 0.1 to 8 μm, and 0.1 to 10 μm, respectively.

Alternatively, when the kinds of active materials of the first and second anode active material layers 124 and 125 are the same, the specific surface areas of the active materials of the first and second anode active material layers 124 and 125 are different by 0.2 to 8m²A/g, of, for example, 0.2m²/g、0.5m²/g、1m²/g、2m²/g、3m²/g、4m²/g、5m²/g、6m²/g、7m²G or 8m²/g。

Alternatively, when the kinds of active materials of the first and second anode active material layers 124 and 125 are the same, the gram capacities of the active materials of the first and second anode active material layers 124 and 125 differ by 10 to 100mAh/g, for example, 10mAh/g, 20mAh/g, 30mAh/g, 40mAh/g, 50mAh/g, 60mAh/g, 70mAh/g, 80mAh/g, 90mAh/g, or 100 mAh/g.

Alternatively, when the kinds of the active materials of the first and second anode active material layers 124 and 125 are the same, the compacted densities of the active materials of the first and second anode active material layers 124 and 125 are different by 0.1 to 1.8g/cm³For example, 0.1g/cm³、0.3g/cm³、0.5g/cm³、0.8g/cm³、1.0g/cm³、1.1g/cm³、1.3g/cm³、1.5g/cm³Or 1.8g/cm³。

Optionally, the thickness of the third conductive layer 122 and the fourth conductive layer 123 is 0.1-2 um. When the types of active materials of the first and second anode active material layers 124 and 125 are the same, the difference in thickness between the third and fourth

conductive layers

122 and 123 is 0.1 to 1 μm. Alternatively, the difference in thickness between the first negative electrode active material layer 124 and the second negative electrode active material layer 125 is 5 to 100 μm.

When the active material species of the first anode active material layer 124 and the second anode active material layer 125 are not the same, it may be so arranged that: the first negative active material layer 124 is graphite, and the second negative active material layer 125 is silicon carbon; alternatively, the first negative electrode active material layer 124 is silicon carbon, and the second negative electrode active material layer 125 is graphite; alternatively, the first negative electrode active material layer 124 is silicon carbon, and the second negative electrode active material layer 125 is mesocarbon microbeads.

Illustratively, when the types of the active materials of the first and second anode active material layers 124 and 125 are different, the particle diameters of D10, D50, and D90 of the active materials of the first and second anode active material layers 124 and 125 are different by 0.1 to 4 μm, 0.1 to 10 μm, and 0.1 to 20 μm, respectively.

Alternatively, the active materials of the first negative electrode active material layer 124 and the second negative electrode active material layer 125 have a difference of 0.5 to 8m in specific surface area²A/g, of, for example, 0.5m²/g、1m²/g、2m²/g、3m²/g、4m²/g、5m²/g、6m²/g、7m²G or 8m²/g。

Optionally, the gram capacities of the active materials of the first negative active material layer 124 and the second negative active material layer 125 differ by 10 to 200mAh/g, for example 10mAh/g, 20mAh/g, 30mAh/g, 40mAh/g, 50mAh/g, 60mAh/g, 70mAh/g, 80mAh/g, 90mAh/g, 100mAh/g, 120mAh/g, 150mAh/g, 180mAh/g, or 100 mAh/g.

Optionally, the compacted densities of the active materials of the first and second anode active material layers differ by 0.1-1.8 g/cm³For example, 0.1g/cm³、0.3g/cm³、0.5g/cm³、0.8g/cm³、1.0g/cm³、1.1g/cm³、1.3g/cm³、1.5g/cm³Or 1.8g/cm³。

Optionally, when the types of the active materials of the first negative electrode active material layer 124 and the second negative electrode active material layer 125 are different, the thickness difference between the third conductive layer and the fourth conductive layer is 0.1 to 1.8 μm. Alternatively, the difference in thickness between the first negative electrode active material layer 124 and the second negative electrode active material layer 125 is 5 to 100 μm.

The following describes an arrangement manner of tabs of the cell structure 10 according to an embodiment of the present application:

taking the following cell structure as an example, referring to fig. 1, a first negative electrode active material layer 124 and a first positive electrode active material layer 114 which are adjacently disposed are separated by a first separator 13, and a second positive electrode active material layer 115 and a second negative electrode active material layer 125 which are adjacently disposed are separated by a second separator 14. The cell structure 10 has four tabs, which are a first tab 151, a second tab 152, a third tab 153, and a fourth tab 154, respectively, as shown in fig. 9.

The cell structure 10 of the present application is further described in detail with reference to the following embodiments.

Example 1

The present embodiment provides a winding cell structure, which includes positive electrode plates and negative electrode plates alternately arranged.

The positive pole piece comprises a positive pole insulating layer, a first conducting layer and a second conducting layer on two surfaces of the positive pole insulating layer, a first positive pole active material layer on the surface of the first conducting layer, and a second positive pole active material layer on the surface of the second conducting layer. The first conducting layer and the second conducting layer are arranged at the lug in a staggered mode, the first conducting layer and the positive insulating layer extend outwards relative to the second conducting layer to form a first lug, and the second conducting layer and the positive insulating layer extend outwards relative to the first conducting layer to form a second lug.

The negative pole piece comprises a negative pole insulating layer, a third conducting layer and a fourth conducting layer on two surfaces of the negative pole insulating layer, a first negative pole active material layer on the surface of the third conducting layer, and a second negative pole active material layer on the surface of the fourth conducting layer. The third conducting layer and the fourth conducting layer are arranged at the lug in a staggered mode, the third conducting layer and the negative electrode insulating layer extend outwards relative to the fourth conducting layer to form a third lug, and the fourth conducting layer and the negative electrode insulating layer extend outwards relative to the fourth conducting layer to form a fourth lug.

The first lug and the fourth lug are arranged on one side of the winding symmetrical surface of the winding structure, and the second lug and the third lug are distributed on the other side of the winding symmetrical surface of the winding structure; the first tab is disposed between the second tab and the third tab in a length direction of the winding structure.

The first negative active material layer and the first positive active material layer in the adjacent positive pole piece and the negative pole piece that set up are close to the setting, and second positive active material layer and second negative active material layer are close to the setting, and the first negative active material layer and the first positive active material layer of adjacent setting pass through first barrier film separation, and the second positive active material layer and the second negative active material layer of adjacent setting pass through the second barrier film separation.

Capacity ratio (CB) of the first negative electrode active material layer to the first positive electrode active material layer₁Value) was 1.1, and the capacity ratio (CB) of the second negative electrode active material layer to the second positive electrode active material layer₂Value) was 1.1.

The specific parameters of the active materials of the first positive electrode active material layer, the second positive electrode active material layer, the first negative electrode active material layer, and the second negative electrode active material layer are shown in tables 1 and 2.

Note that, not specifically described in the present embodiment, it means that the first cathode active material layer and the second cathode active material layer are the same in this respect, and the first anode active material layer and the second anode active material layer are the same in this respect.

Example 2

Example 2 provides a wound cell structure having the same structure as that of example 1 except that the active materials of the first positive electrode active material layer and the second positive electrode active material layer of example 2 are different from those of example 1 in the arrangement, and the active materials of the first negative electrode active material layer and the second negative electrode active material layer are different from those of example 1 in the arrangement, wherein the arrangement conditions of the first positive electrode active material layer and the second positive electrode active material layer are recorded in table 1 and the arrangement conditions of the active materials of the first negative electrode active material layer and the second negative electrode active material layer are recorded in table 2.

Comparative example 1

Comparative example 1 provides a wound cell structure having the same structure as that of example 1 except that the lithium iron phosphate in the second positive electrode active material layer of comparative example 1 had a D10 particle size of 0.6 μm, a D50 particle size of 2.8 μm, a D90 particle size of 9.6 μm, and a specific surface area of 12m²G, gram capacity of 146mAh/g, coating amount of 20mg/cm²The compacted density is 2.35g/cm³The weight of the carbon coating layer is 0.8% of the total weight of the carbon coating layer and the lithium iron phosphate.

TABLE 1 partial parameters of first and second positive electrode active material layers of examples 1 to 2 and comparative example 1

Table 2 partial parameters of first and second anode active material layers of examples 1 and 2 and comparative example 1

Test examples

(1) The cell structures of examples 1 to 2 and comparative example 1 were tested for discharge capacity ratio at a discharge rate of 3C at 25 ℃ (discharge capacity ratio to rated capacity), gravimetric energy density, 75% capacity cycle number, operating temperature range, and discharge dc resistance at 50% SOC, and the results are shown in table 3. The direct current resistance testing method under the condition of 50% SOC is characterized in that discharging is carried out for 30S at 25 ℃ and 50% SOC by adopting 3C discharging multiplying power, and discharging direct current resistance DCR is obtained through calculation, wherein DCR is ohm impedance, electrochemical impedance and concentration impedance.

TABLE 3 Performance test results of the cell structures of examples 1-2 and comparative example 1

Compared with the comparative example 1, the active material of the second positive active material layer in the example 1 has small particle size, large specific surface area, short electron migration path and large carbon coating amount, and the active material of the second negative active material layer adopts mesocarbon microbeads which have high gram capacity and good isotropy, so that the multiplying power of the example 1 is improved compared with that of the comparative example 1, the cycle life is greatly prolonged, and the low-temperature working range is widened to-30 ℃. In addition, compared to comparative example 1, since the active material particle size of the second positive electrode active material layer of example 1 is small, the dynamic performance is good, the electrochemical resistance and the concentration resistance are relatively small, the thickness of the first conductive layer is not changed, the ohmic resistance is not changed, and thus the DCR is reduced as a whole. In addition, the particle size distribution of the mesocarbon microbeads of the second negative active material layer is narrow and small, the thickness of the second conductive layer is increased, and the DCR is relatively small.

Comparative example 2 and comparative example 1, compared to comparative example 1, the active material of the second positive electrode active material layer of example 2 is polycrystalline nickel cobalt manganese (811 system), and the gram volume of the polycrystalline nickel cobalt manganese material is much higher than that of lithium iron phosphate, and is also much heavier than that of lithium iron phosphate in unit weight, so that the coating weight and the compaction density are both large, and the weight energy density is improved greatly. In addition, the active material of the second positive electrode active material layer has a large particle size and a small specific surface area, so that the cycle number is greatly reduced. The polycrystalline nickel-cobalt-manganese alloy has good conductivity, does not need carbon coating, and has improved rate capability as a whole. The performance of the polycrystalline nickel-cobalt-manganese material at low temperature is relatively good, so that the working temperature range of the battery core can be expanded to-25 ℃ in a low temperature region. Compared with the comparative example 1, the active material of the second negative active material layer is a silicon-carbon material, so that the gram capacity is higher, the coating weight and the thickness of the pole piece are reduced, and the energy density is also improved compared with the comparative example 1. The volume expansion of example 2 is large during the circulation process, and the particles are easy to break, so that the circulation performance is slightly attenuated. In addition, compared with the comparative example 1, the active material of the second positive electrode active material layer is polycrystalline nickel cobalt manganese, so that the conductive performance is good, the ohmic resistance is favorably reduced, meanwhile, the thickness of the second conductive layer is increased, the overcurrent capacity is improved, and the ohmic resistance is reduced to a greater degree on the whole. The electrochemical impedance and concentration impedance of the polycrystalline nickel-cobalt-manganese alloy are not larger than that of lithium iron phosphate, so that the DCR is reduced to a greater extent. Compared with the comparative example 1, the silicon carbon material of the example 2 has slightly reduced conductive performance (which can lead to the increase of DCR), but the thickness of the conductive layer is increased, and the overall effect is that the effect of the negative electrode on the DCR is slightly increased, but the effect of the positive electrode is larger, so that the DCR is reduced as a whole.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A cell structure, comprising: the positive pole piece and the negative pole piece are alternately arranged;

the positive pole piece comprises a positive insulating layer, a first conducting layer and a second conducting layer on two surfaces of the positive insulating layer, a first positive active material layer on the surface of the first conducting layer, and a second positive active material layer on the surface of the second conducting layer;

the adjacent positive pole piece and the adjacent negative pole piece are separated by an isolating membrane;

the currents of the first conducting layer and the second conducting layer of the positive pole piece are respectively led out through a first pole lug and a second pole lug;

and the currents of the third conducting layer and the fourth conducting layer of the negative pole piece are respectively led out through a third lug and a fourth lug.

2. The cell structure of claim 1, wherein the first conductive layer and the second conductive layer of the positive pole piece are arranged in a staggered manner at a tab, the first conductive layer and the positive insulating layer extend outward relative to the second conductive layer to form a first tab, and the second conductive layer and the positive insulating layer extend outward relative to the first conductive layer to form a second tab;

the third conducting layer of the negative pole piece and the fourth conducting layer are arranged at the position of a pole lug in a staggered mode, the third conducting layer and the negative pole insulating layer are opposite, the fourth conducting layer extends outwards to form a third pole lug, and the fourth conducting layer and the negative pole insulating layer extend outwards to form a fourth pole lug relative to the fourth conducting layer.

3. The cell structure of claim 1, wherein the first tab, the second tab, the third tab, and the fourth tab are disposed on the same side of the cell structure in a height direction.

4. The cell structure of claim 1, wherein two of the first tab, the second tab, the third tab, and the fourth tab are disposed on one side of the cell structure, and the other two are disposed on the other side of the cell structure in the height direction.

5. The cell structure according to claim 3 or 4, wherein the cell structure is a winding structure, the first tab and the fourth tab are disposed on one side of a winding symmetry plane of the winding structure, and the second tab and the third tab are distributed on the other side of the winding symmetry plane; in the length direction of the winding structure, the first tab is disposed between the second tab and the third tab.

6. The cell structure according to claim 3 or 4, wherein the cell structure is a winding structure, the second tab and the third tab are distributed on one side of a winding symmetry plane of the winding structure, and the first tab and the fourth tab are distributed on the other side of the winding symmetry plane; in a length direction of the winding structure, the fourth tab is disposed between the second tab and the third tab.

7. The cell structure according to claim 3 or 4, wherein the cell structure is a winding structure, the first tab and the second tab are distributed on one side of a winding symmetry plane of the winding structure, and the third tab and the fourth tab are distributed on the other side of the winding symmetry plane; in a length direction of the winding structure, the third tab is disposed between the first tab and the second tab.

8. The cell structure according to claim 3 or 4, wherein the cell structure is a winding structure, the first tab and the second tab are distributed on one side of a winding symmetry plane of the winding structure, and the third tab and the fourth tab are distributed on the other side of the winding symmetry plane; in the length direction of the winding structure, the first tab is disposed between the third tab and the second tab.

9. The cell structure of claim 3 or 4, wherein the cell structure is a winding structure, and the first tab, the second tab, the third tab and the fourth tab are disposed on the same side of a winding symmetry plane of the winding structure.

10. The cell structure according to any one of claims 1 to 4, wherein the first positive electrode active material layer and the second positive electrode active material layer are different;

and/or the first negative electrode active material layer and the second negative electrode active material layer are different.