CN113285056A

CN113285056A - Positive plate and battery

Info

Publication number: CN113285056A
Application number: CN202110601256.8A
Authority: CN
Inventors: 张保海; 彭冲; 李俊义
Original assignee: Zhuhai Cosmx Battery Co Ltd
Current assignee: Zhuhai Cosmx Battery Co Ltd
Priority date: 2021-05-31
Filing date: 2021-05-31
Publication date: 2021-08-20
Anticipated expiration: 2041-05-31
Also published as: CN113285056B

Abstract

The invention provides a positive plate and a battery, wherein the positive plate comprises a positive current collector and a positive coating, the positive current collector comprises a first base material and a conductive coating, the conductive coating is arranged on two opposite side surfaces of the first base material, and the first base material comprises a polymer layer; the positive current collector comprises a first side face and a second side face which are opposite, and the positive coating is arranged on at least one of the first side face and the second side face. The polymer layer coated with the conductive coating is used as a positive current collector of the positive plate, so that the risk of internal short circuit can be reduced, and the safety performance of the battery is improved.

Description

Positive plate and battery

Technical Field

The invention relates to the technical field of lithium ion batteries, in particular to a positive plate and a battery.

Background

With the continuous development and progress of society, electronic equipment with various functions is rapidly developed. The lithium battery has the advantages of high battery voltage, high energy density, good cycle performance and the like, so that the application demand of the lithium battery on various electronic devices is increasing.

When the lithium battery is used incorrectly, and is impacted or punctured by a sharp object, the positive aluminum foil and the negative active material in the battery are usually contacted, so that the internal short circuit of the battery is caused, and in severe cases, the battery can be ignited and even explode, thereby endangering the personal safety of users. Therefore, the problem that the short circuit risk is large exists in the conventional lithium battery.

Disclosure of Invention

The embodiment of the invention aims to provide a positive plate, a battery and a preparation method of the positive plate, and solves the problem of low safety performance of the battery in the prior art.

In order to achieve the above object, in a first aspect, an embodiment of the present invention provides a positive electrode sheet, including a positive electrode current collector and a positive electrode coating, where the positive electrode current collector includes a first substrate and a conductive coating, the conductive coating is disposed on two opposite sides of the first substrate, and the first substrate includes a polymer layer; the positive current collector comprises a first side face and a second side face which are opposite, and the positive coating is arranged on at least one of the first side face and the second side face.

Optionally, the first substrate further comprises a ceramic coating disposed on two opposite sides of the polymer layer, and the conductive coating is disposed on a side of the ceramic coating opposite the polymer layer.

Optionally, the positive electrode coating is disposed on each of the first side and the second side, the positive electrode current collector includes a first end and a second end that are opposite to each other, the positive electrode coating on the first side includes a first edge and a second edge that are opposite to each other, the first edge is close to the first end, and the second edge is close to the second end; the positive electrode coating of the second side includes opposing third and fourth edges, the third edge being proximate the first end and the fourth edge being proximate the second end; the first side comprises a first area between the second edge and the second end, the second side comprises a second area between the fourth edge and the second end; the first region and the second region are not provided with the positive electrode coating.

Optionally, the length of the first region is less than the length of the second region.

Optionally, the winding device further comprises a gummed paper, one part of the gummed paper is attached to the positive electrode coating on the second side surface, the other part of the gummed paper is attached to the second area, the length of the gummed paper attached to the second area is greater than or equal to the perimeter of the first winding layer, and the first winding layer is the winding layer where the gummed paper is located after the positive electrode sheet is wound.

Optionally, a positive tab is further included, the first side includes a third region located between the first edge and the first end, the second side includes a fourth region located between the third edge and the first end; the third area and the fourth area are not provided with the anode coating, and the anode tab is in contact with the third area and the fourth area.

Optionally, the positive tab includes a first extension portion and a second extension portion, and an included angle between the first extension portion and the second extension portion is less than 180 °; the first extension portion is disposed in one of the third region and the fourth region, the second extension portion is disposed in the other of the third region and the fourth region, and the first extension portion and the second extension portion are electrically connected.

In a second aspect, an embodiment of the present invention provides a battery, including a battery cell and a casing, where the battery cell is disposed in the casing, the battery cell is formed by sequentially stacking and winding positive electrode sheets and negative electrode sheets, a separator sheet is disposed between any adjacent one of the positive electrode sheets and one of the negative electrode sheets, and the positive electrode sheet is the positive electrode sheet provided in the first aspect of the embodiment of the present invention.

Optionally, the housing is an electrically conductive shell; the first side surface and the second side surface are both provided with the anode coatings, and the anode current collector comprises a first end and a second end which are opposite; the positive electrode coating of the first side includes opposing first and second edges, the first edge being proximate the first end and the second edge being proximate the second end, the first side including a first region, the first region being located between the second edge and the second end; the positive coating of the second side includes opposing third and fourth edges, the third edge being proximate the first end, the fourth edge being proximate the second end, the second side including a second region, the second region being located between the fourth edge and the second end; the first area and the second area are not provided with the anode coating, and the second area is attached to the inner wall of the shell.

Optionally, the second end is bent in a first direction to form a bent portion, the first direction is opposite to a winding direction of the battery cell, the bent portion includes a first sub-region and a second sub-region that are opposite to each other, the first region includes the first sub-region, the second region includes the second sub-region, and the first sub-region is attached to the inner wall of the housing.

One of the above technical solutions has the following advantages or beneficial effects:

the embodiment of the invention provides a positive plate, a battery and a preparation method of the positive plate, wherein the positive plate comprises a positive current collector and a positive coating, the positive current collector comprises a first base material and a conductive coating, the conductive coating is arranged on two opposite side surfaces of the first base material, and the first base material comprises a polymer layer. The positive plate is different from the positive plate in the prior art in that an aluminum foil is used as a positive current collector of the positive plate, and a polymer layer coated with a conductive coating is used as the positive current collector of the positive plate. The conductive coating can ensure the conductivity between the anode particles in the anode coating in the horizontal direction, reduces the use of the anode aluminum foil, can reduce the risk of internal short circuit, and improves the safety performance of the battery.

Drawings

Fig. 1 is a cross-sectional view of a positive electrode sheet according to an embodiment of the present invention;

fig. 2 is a cross-sectional view of a positive electrode current collector provided in an embodiment of the present invention;

fig. 3 is a cross-sectional view of a battery cell according to an embodiment of the present invention;

fig. 4 is a second cross-sectional view of a positive electrode plate according to an embodiment of the present invention;

fig. 5 is a structural diagram of a positive tab according to an embodiment of the present invention;

fig. 6 is a top view structural diagram of a positive plate according to an embodiment of the present invention;

fig. 7 is a second cross-sectional view of a battery cell according to an embodiment of the invention;

fig. 8 is a flowchart of a method for manufacturing a positive electrode plate according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. 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 invention.

Referring to fig. 1 to 7, an embodiment of the invention provides a positive electrode sheet 100.

As shown in fig. 1 and 2, the positive electrode sheet 100 includes a positive electrode collector 110 and a positive electrode coating 120, the positive electrode collector 110 includes a first substrate and a conductive coating 111, the conductive coating 111 is disposed on two opposite sides of the first substrate, and the first substrate includes a polymer layer 112; the positive current collector 110 includes first and second opposite sides, at least one of which is provided with a positive coating 120.

Here, the first side surface may be understood as an upper side surface as shown in fig. 1, and the first side surface is an inner side of winding when the positive electrode sheet 100 is wound; the second side may be understood as a lower side as shown in fig. 1, which is an outer side of winding when the positive electrode sheet 100 is wound.

In embodiments of the present invention, the polymer layer 112 may include one or more of a polyethylene single layer film, a polypropylene single layer film, and a polyethylene and polypropylene multi-layer composite film. Moreover, the polymer layer 112 has a pore channel, the pore channel can conduct the first side and the second side of the polymer layer 112, and under the condition that the positive electrode coating is arranged on both the first side and the second side, lithium ions in the positive electrode coating on the first side can move into the positive electrode coating on the second side through the pore channel, or lithium ions in the positive electrode coating on the second side can move into the positive electrode coating on the first side through the pore channel, so that the lithium ions in the whole positive electrode sheet are more balanced, the polarization is reduced, and the cycle life of the lithium ions is prolonged. It should be noted that after the conductive coating 111 is disposed, the pore passages still conduct the first side and the second side of the positive current collector 110.

In a specific implementation, the pore passage may be a straight-through hole or a curved-through hole, which may be determined according to an actual situation, and is not limited herein. Optionally, the porosity of the polymer layer 112 is 35% to 60%, and the porosity of the positive electrode collector 110, i.e., the porosity after the polymer layer 112 is coated with the conductive coating 111, is 30% to 50%, wherein the porosity is a percentage of the volume of the pore channels to the entire volume. Alternatively, the elongation of the polymer layer 112 is 75% to 210%, and the elongation of the positive electrode collector 110, i.e., after the polymer layer 112 is coated with the conductive coating 111, is 90% to 230%.

In the embodiment of the present invention, unlike the prior art in which an aluminum foil is used as the positive electrode current collector of the positive electrode sheet, the polymer layer 112 coated with the conductive coating 111 is used as the positive electrode current collector 110 of the positive electrode sheet 100. On one hand, since the conductive coating 111 is coated outside the polymer layer 112, the conductive coating 111 can be fully contacted with the active material in the positive electrode coating 120, so that the conductivity between the positive electrode particles in the positive electrode coating 120 in the horizontal direction can be ensured, and the current generated by the positive electrode particles in the positive electrode coating 120 is collected to form the current for outputting to the outside. On the other hand, because the use of aluminum foil is reduced, the contact between the aluminum foil and the negative active material can be effectively avoided, the risk of internal short circuit is reduced, and based on the pore structure of the polymer layer 112, the lithium ions of the whole positive plate 100 can be more balanced, and the cycle life of the lithium ions is prolonged. In addition, the polymer layer 112 has good mechanical strength and flexibility, and can effectively prevent the powder falling phenomenon caused by pole piece bending caused by improper operation during battery assembly.

Optionally, as shown in fig. 2, the first substrate further includes a ceramic coating 113, the ceramic coating 113 is disposed on two opposite sides of the polymer layer 112, and the conductive coating 111 is disposed on the ceramic coating 113.

In practical applications, after the slurry of the positive electrode coating layer 120 is coated on at least one side surface of the positive electrode current collector 110, the slurry needs to be dried at a high temperature. Since the positive electrode collector 110 uses the polymer layer 112 as a substrate, it may shrink when exposed to heat. Specifically, optionally, before the ceramic coating 113 is not coated, the thermal shrinkage of the polymer layer 112 at 90 ℃ to 105 ℃ is 2% to 5%, the thermal shrinkage above 130 ℃ can reach 70% to 93%, and the thermal shrinkage of the positive electrode current collector 110, i.e., the polymer layer 112 after being coated with the conductive coating 111 at 125 ℃ to 145 ℃ is 10% to 18%.

In this embodiment, a ceramic coating 113 may be coated on two opposite sides of the polymer layer 112, and the conductive coating 111 is disposed on the side of the ceramic coating 113 opposite to the polymer layer 112. The ceramic coating 113 can effectively increase the heat shrinkage resistance of the polymer layer 112, and prevent the polymer layer 112 from shrinking during the high-temperature baking process.

In a specific implementation, when the conductive coating 111 is formed by applying the conductive paste on the ceramic coating 113, the conductive paste penetrates through gaps between the ceramic particles in the ceramic coating 113, so that the ceramic particles and the conductive paste are connected to each other in the ceramic coating 113 in a mesh-like weave, which can improve the adhesion between the conductive coating 111 and the ceramic coating 113 and the conductivity in the vertical direction of the ceramic coating 113. It is understood that the penetration of the conductive paste in the ceramic coating 113 decreases from the surface layer to the bottom layer of the ceramic coating 113 in order.

Alternatively, the first substrate, i.e., the polymer layer 112, has a thermal shrinkage of 3% to 6% at 125 ℃ to 145 ℃ after being coated with the ceramic coating 113, and the positive electrode current collector 110, i.e., the polymer layer 112, has a thermal shrinkage of 2% to 7% at 125 ℃ to 145 ℃ after being coated with the ceramic coating 113 and the conductive coating 111. It should be noted that, alternatively, the porosity of the first substrate, i.e., the polymer layer 112 after being coated with the ceramic coating 113, is 40% to 65%, and the porosity of the positive electrode collector 110, i.e., the polymer layer 112 after being coated with the ceramic coating 113 and the conductive coating 111, is 33% to 57%. Alternatively, the elongation of the first substrate, i.e., the polymer layer 112 after being coated with the ceramic coating 113, is 60% to 130%, and the elongation of the positive electrode collector 110, i.e., the polymer layer 112 after being coated with the ceramic coating 113 and the conductive coating 111, is 85% to 140%.

Optionally, as shown in fig. 1, the first side and the second side are both provided with a positive electrode coating, and for convenience of reading, the positive electrode coating of the first side is represented as a positive electrode coating 121, and the positive electrode coating of the second side is represented as a positive electrode coating 122; the positive current collector 110 includes opposing first and second ends, the positive coating 121 includes opposing first and second edges, the first edge being proximate the first end and the second edge being proximate the second end; the positive coating 122 includes opposing third and fourth edges, the third edge being proximate the first end and the fourth edge being proximate the second end; the first side comprises a first area between the second edge and the second end, the second side comprises a second area between the fourth edge and the second end; the first region and the second region are not provided with the positive electrode coating.

Here, the first end may be understood as a left end as shown in fig. 1, and when the positive electrode sheet 100 is wound, the first end is a head of the winding; the second end may be understood as a right end as shown in fig. 1, and is a tail of winding when the positive electrode tab 100 is wound. The first edge may be understood as a left side edge of the positive electrode coating 121 as shown in fig. 1, and the second edge may be understood as a right side edge of the positive electrode coating 121 as shown in fig. 1; the third edge may be understood as a left side edge of the positive electrode coating 122 as shown in fig. 1, and the fourth edge may be understood as a right side edge of the positive electrode coating 122 as shown in fig. 1. The first region may be understood as a region on the upper right side where the positive electrode coating 121 is not coated as shown in fig. 1, and the second region may be understood as a region on the lower right side where the positive electrode coating 122 is not coated as shown in fig. 1.

In this embodiment, as shown in fig. 1, the upper and lower side surfaces of the positive electrode current collector 110 are both provided with positive electrode coatings, and the two sides of the tail portion of the positive electrode sheet 100 are both exposed from the positive electrode current collector 110, because the positive electrode current collector 110 includes the conductive coating 111, the positive electrode current collector 110 can contact with the inner wall of the conductive battery case after winding is completed to serve as a positive electrode tab of the battery, and the positive electrode tab is not required to be arranged on the positive electrode sheet 100.

In one implementation, as shown in fig. 3, after the positive electrode sheet 100 is wound, the positive electrode current collector 110 exposed at the tail of the positive electrode sheet 100 may surround at least the outermost turn of the wound cell for a full circle. The exposed second side surface of the positive electrode current collector 110, i.e., the second region, may be in close contact with the inner wall of the battery case, which may be conductive, so as to improve the conductive stability of the positive electrode tab 100.

In one form of implementation, the first edge is flush with the third edge.

Further, optionally, a length of the first region is less than a length of the second region.

In this embodiment, the positive electrode sheet 100 is close to the second end, that is, a portion having only a single-sided coating layer is present at the tail of the positive electrode sheet 100. As shown in fig. 3, when the positive electrode sheet 100 and the negative electrode sheet 200 are stacked and wound, a separator sheet is provided between the positive electrode sheet 100 and the negative electrode sheet 200 to facilitate the flow of lithium ions and to perform an insulating function. In the latter half of the winding, the negative electrode tab 200 is not present between the positive electrode tab 100 and the battery case. If the second side surface is also provided with the anode coating, lithium ions in the anode coating can not reach the cathode plate after being extracted, and the lithium can be separated out from the battery shell. Thus, the outer side, i.e., the second side, around which the positive electrode current collector 110 is wound is not provided with the positive electrode coating layer at the tail portion of the positive electrode sheet 100.

Further, optionally, the positive electrode sheet 100 further includes a glue paper 130, a portion of the glue paper 130 is attached to the positive electrode coating 122, another portion of the glue paper 130 is attached to the second area, and a length of the glue paper 130 attached to the second area is greater than or equal to a circumference of a first winding layer, where the glue paper 130 is located after the positive electrode sheet is wound.

In the present embodiment, since the positive electrode collector 110 uses the polymer layer 112 as a base material, and there is a portion of the tail of the positive electrode sheet 100 where only one-side coating is provided, lithium ions in the positive electrode coating 121 can penetrate through the polymer layer 112 to reach the lower side surface of the positive electrode collector 110 at the tail of the positive electrode sheet 100, i.e., at the right end as shown in fig. 1. Meanwhile, as described above, in the latter half of the winding of the positive electrode sheet 100, the negative electrode sheet 200 does not exist between the positive electrode sheet 100 and the battery case, and thus lithium ions penetrating onto the positive electrode coating 122 may cause a lithium deposition situation. Thus, the adhesive paper 130 may be attached to a portion of the lower side of the positive electrode collector 110 where the positive electrode coating 122 is not disposed to prevent lithium ions from being precipitated. The adhesive paper 130 can surround a whole circle of the winding layer to prevent the lithium ions from being separated out from any position of the winding layer.

In addition, a part of the adhesive tape 130 is attached to the positive electrode coating 122, so that in the second half of winding, the negative electrode coating adjacent to the positive electrode coating 122 can completely cover the positive electrode coating, and the phenomenon that burrs are generated at the tail part of the positive electrode coating 122 to pierce through the polymer layer 112 to cause lithium precipitation can be avoided in the charging process. Note that the adhesive tape may also be attached to the tail portion of the positive electrode coating 121 to prevent burrs from being generated at the tail portion of the positive electrode coating 121 to pierce through the polymer layer 112 and cause lithium precipitation.

In specific implementation, the length of the adhesive tape 130 can be 10mm to 15mm from the length of the positive electrode coating 121 to the length of the positive electrode coating 122; the degree of the adhesive tape 130 attached to the positive electrode coating layer 122 may be 2mm to 5mm, and may be determined according to actual conditions, which is not limited herein.

Optionally, as shown in fig. 4, the positive tab 100 further includes a positive tab 140, the first side includes a third region located between the first edge and the first end, the second side includes a fourth region located between the third edge and the first end; the positive electrode coating 120 is not disposed in the third region and the fourth region, and the positive electrode tab 140 is in contact with the third region and the fourth region.

Here, the third region may be understood as a region where the upper left side is not coated with the positive electrode coating 121 as shown in fig. 4, and the fourth region may be understood as a region where the lower left side is not coated with the positive electrode coating 122 as shown in fig. 4.

In the present embodiment, as shown in fig. 4, a tab installation area is provided on the left side of the positive electrode sheet 100, and the positive electrode tab 140 may be installed in the tab installation area. Under the condition that the positive electrode current collector 110 is exposed at both sides of the tail part of the positive electrode plate 100, and the part of the positive electrode current collector 110 is in contact with the inner wall of the conductive battery shell after winding is completed to serve as the first positive electrode tab of the battery, the positive electrode tab 140 can serve as the second positive electrode tab of the positive electrode plate 100, and the arrangement of the bipolar tabs can improve the charging speed of the battery, so that the quick charging capacity of the battery is improved.

In particular implementation, since the positive electrode collector 110 includes the polymer layer 112, the upper side and the lower side of which are not conductive, the positive electrode tab 140 needs to be in contact with both the third area and the fourth area to ensure the conductivity of the positive electrode sheet 100.

In this embodiment, in an implementation form, as shown in fig. 5, the positive tab 140 includes a first extending portion 141 and a second extending portion 142, and an included angle between the first extending portion 141 and the second extending portion 142 is less than 180 °; the first extension portion 141 is disposed in one of the third region and the fourth region, the second extension portion 142 is disposed in the other of the third region and the fourth region, and the first extension portion 141 and the second extension portion 142 are electrically connected.

Wherein the first extension 141 includes a portion covering the upper side of the positive electrode collector 110 as shown in fig. 5; the second extension 142 includes a portion covering the lower side of the positive electrode collector 110 as shown in fig. 5.

In this embodiment, as shown in fig. 5, the positive tab 140 is an "eight" clip-type tab. The first extension 141 and the second extension 142 may be electrically conducted by soldering through the positive electrode collector 110, or may be electrically conducted by the pore passage, so that the active material of the conductive coating 111 is filled in the pore passage, so as to achieve the electrical conduction between the first extension 141 and the second extension 142. It should be noted that, for the convenience of packaging, the portion of the positive tab 140 not in contact with the positive current collector 110 may be provided with an insulator 150. Further, as shown in fig. 6, the width of the portion of the positive electrode tab 140 that does not contact the positive electrode collector 110 is the same as the width of the portion of the positive electrode tab 140 that contacts the positive electrode collector 110, which can further improve the conductivity between the positive electrode tab 140 and the positive electrode collector 110.

In summary, the positive electrode plate provided in the embodiments of the present invention is different from the positive electrode plate in the prior art in that an aluminum foil is used as a positive electrode current collector of the positive electrode plate, and a polymer layer coated with a conductive coating is used as the positive electrode current collector of the positive electrode plate, so that the risk of internal short circuit can be reduced, and the safety performance of the battery can be improved.

The embodiment of the present invention further provides a battery, as shown in fig. 3 and fig. 7, which includes a battery core and a casing 300, where the battery core is disposed in the casing 300, the battery core is formed by sequentially stacking and winding a positive plate 100 and a negative plate 200, a separator (not shown in the figure) is disposed between any adjacent positive plate 100 and any adjacent negative plate 200, and the positive plate 100 is the positive plate 100 provided in the embodiment of the present invention.

It should be noted that, in the embodiment of the present invention, the battery includes all the technical features of the positive electrode sheet 100 provided in the embodiment of the present invention, and can achieve all the technical effects of the positive electrode sheet 100 provided in the embodiment of the present invention, and in order to avoid repetition, details are not described here again.

Alternatively, as shown in fig. 3, the housing 300 is a conductive shell; the first side includes a first area between the second edge and the second end; the second side includes a second region proximate the second end, the second region being located between the fourth edge and the second end; the first region and the second region are not provided with the positive electrode coating, and the second region is attached to the inner wall of the housing 300.

In this embodiment, the battery structure is as shown in fig. 3, the positive electrode current collector 110 exposed at both sides of the tail portion of the positive electrode sheet 100, because the positive electrode current collector 110 includes the conductive coating 111, the positive electrode current collector 110 can contact with the inner wall of the conductive housing 300 after winding is completed to serve as the positive electrode tab of the battery, the negative electrode tab of the negative electrode sheet 200 can be connected with the bottom cover of the conductive housing 300 to serve as the negative electrode tab 210 of the battery, and at this time, insulation between the inner wall of the conductive housing 300 and the bottom cover needs to be ensured.

In this embodiment, preferably, the inner wall of the conductive housing 300 may be provided with a conductive coating to reduce contact resistance between the inner wall of the conductive housing 300 and the positive electrode current collector 110, thereby further enhancing conductivity.

In this embodiment, as shown in fig. 3, a bent portion is formed by bending the second end toward a first direction, the first direction is opposite to the winding direction of the battery cell, the bent portion includes a first sub-region and a second sub-region opposite to each other, the first region includes the first sub-region, the second region includes the second sub-region, and the first sub-region is attached to the inner wall of the conductive shell 300.

The first direction is opposite to the winding direction of the battery cell, and for example, as shown in fig. 3 and 7, if the winding direction of the positive electrode tab 100 is a clockwise direction, the first direction is a counterclockwise direction.

As can be seen from the above embodiments, the second region, i.e., the tail portion of the upper surface of the positive electrode collector 110 is attached to the inner wall of the casing 300 to achieve electrical conduction. Since the positive electrode current collector 110 includes a polymer layer, the upper and lower sides of the positive electrode current collector 110 are not electrically conductive, and therefore, in order to ensure the conductivity of the positive electrode tab, the tail of the lower side of the positive electrode current collector 110 needs to be attached to the inner wall of the conductive shell 300 to achieve electrical conductivity. In view of this, in the present embodiment, as shown in fig. 3, the tail portion of the positive electrode current collector 110 may be bent backward, so that the tail portion of the lower side surface of the positive electrode current collector 110, i.e., the first sub-region) is also attached to the inner wall of the casing 300 to achieve electric conduction.

In one embodiment, as shown in fig. 7, the positive electrode tab 100 further includes a positive electrode tab 140, the first side includes the third region, the second side includes the fourth region, and the positive electrode tab 140 is in contact with both the third region and the fourth region.

In this embodiment, the battery structure is as shown in fig. 7, the positive electrode current collector 110 exposed at both sides of the tail portion of the positive electrode sheet 100, because the positive electrode current collector 110 includes the conductive coating 111, the positive electrode current collector 110 can contact with the inner wall of the conductive housing 300 after winding is completed to serve as a first positive electrode tab of the battery, the positive electrode tab 140 can be electrically connected with the top cover of the conductive housing 300 to serve as a second positive electrode tab of the battery, the negative electrode tab of the negative electrode sheet 200 can be connected with the bottom cover of the conductive housing 300 to serve as the negative electrode tab 210 of the battery, and at this time, insulation between the top cover, the inner wall and the bottom cover of the conductive housing 300 needs to be ensured. The arrangement of the double tabs can improve the charging speed of the battery, and further improve the quick charging capacity of the battery.

In summary, the battery provided in the embodiment of the present invention includes a positive plate, which is different from a positive current collector of a positive plate that uses an aluminum foil and uses a polymer layer coated with a conductive coating as the positive current collector of the positive plate in the prior art, so that the risk of internal short circuit can be reduced and the safety performance of the battery can be improved.

Referring to fig. 8, fig. 8 is a flowchart of a method for manufacturing a positive electrode plate according to an embodiment of the present invention. As shown in fig. 8, the method for preparing the positive electrode sheet includes:

step 801, forming a first substrate, wherein the first substrate comprises a polymer layer;

step 802, coating conductive coating slurry on two opposite sides of the first substrate and drying to obtain a positive current collector, wherein the conductive coating slurry is formed by mixing a conductive agent and a solvent;

and 803, coating the positive coating slurry on at least one side surface of the positive current collector and drying to obtain the positive plate, wherein the positive coating slurry is formed by mixing a positive active material, a conductive agent, a binder and a solvent.

The first substrate in the present example is described below.

In an embodiment of the present invention, the first substrate includes a polymer layer, and the polymer layer is formed with a pore channel, and an implementation form of the pore channel may refer to the description in the above embodiment, which is not repeated herein.

The conductive coating in the embodiment of the present invention is described below.

In the embodiment of the invention, the conductive coating slurry of the conductive coating can be formed by mixing a conductive agent and a solvent. Further, the conductive coating paste may further include, but is not limited to, a binder, an adhesion promoter, a heat stabilizer, a curing agent, a dispersant, and a solvent, and is not limited thereto. Wherein, the thermal stability of the conductive coating can be enhanced by adding a thermal stabilizer.

Wherein, the conductive agent may include one or more of Carbon black particles, Carbon nanotubes, Carbon fibers, graphene, Carbon nanofibers (VGCF), and conductive glass fibers.

The curing agent may include one or more of isocyanate, methylimidazole, 3-aminopropylimidazole, 2-ethyl-4-methylimidazole, dimethylaniline, methyl tetrahydrophthalic anhydride, dodecylmaleic anhydride, methyl tetrahydrophthalic anhydride, toluene diisocyanate, diphenylmethane diisocyanate, phenyl-dimethyl urea, 2-ethylimidazole, 2-phenylimidazole, dicyandiamide, triethylamine, 1-cyanoethyl-2-ethyl-4-methylimidazole, phthalic anhydride, pyromellitic dianhydride, 308-eleostearic acid anhydride, methyl endomethyltetrahydrophthalic anhydride, maleic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, meta-phenylene diamine, 651 low-amide molecular weight, T31 phenolic modified amine.

The binder may include one or more of polyvinylidene fluoride, polyvinylidene fluoride to trifluoroethylene, polyvinylidene fluoride to tetrafluoroethylene, polyvinylidene fluoride to hexafluoroethylene, polyvinylidene fluoride to hexafluoropropylene, styrene-acrylic emulsion, polyethylacrylate, polymethyl methacrylate, polybutyl methacrylate, polyvinyl alcohol, ethylene to vinyl acetate copolymer, polyvinyl acetate, polyurethane.

The tackifier may comprise a resinous binder including phenolic, polyacrylic, polyurethane, epoxy. Wherein the epoxy resin may include any one of: bisphenol a glycidyl ether type, bisphenol F type epoxy resins, glycidyl epoxy resins, aliphatic epoxy resins, and aliphatic epoxy resins.

The heat stabilizer may include one or more of 2, 6 to tert-butyl to 4 to methylphenol, triphenyl phosphite, trisnonylphenyl phosphite.

The solvent may include one or more of toluene, xylene, methanol, ethanol, acetone, tetrahydrofuran, N-methylpyrrolidone, NMP, and water.

In the embodiment of the invention, the conductive coating slurry can be obtained by fusing the components according to a preset proportion. The preset proportion can be 10 to 45 parts of conductive agent, 1 to 5 parts of dispersant, 5 to 15 parts of binder, 0.5 to 3 parts of heat stabilizer, 30 to 70 parts of tackifier, 1 to 7 parts of curing agent and 100 parts of solvent. Preferably, the preset proportioning can be 10 to 30 parts of conductive agent, 1 to 3 parts of dispersant, 5 to 10 parts of binder, 0.5 to 1.5 parts of heat stabilizer, 40 to 55 parts of tackifier, 1 to 4 parts of curing agent and 100 parts of solvent. Preferably, the conductive agent is 10 to 30 parts, the dispersing agent is 1 to 3 parts, the binder is 5 to 10 parts, the heat stabilizer is 0.5 to 1.5 parts, the tackifier is 40 to 55 parts, the curing agent is 1 to 4 parts, and the solvent is 100 parts.

In specific implementation, the conductive coating slurry can be prepared according to the following steps:

1) adding 50% of solvent into conductive agent and dispersant, stirring thoroughly, and ultrasonic dispersing. Then, a binder is added to the above solution, and sufficient stirring is performed while ultrasonic dispersion is performed. Thereafter, the above solution was heated to 30 ℃ to 60 ℃ to obtain a solution A.

2) Adding tackifier and heat stabilizer into the rest 50% of solvent, stirring at 60-90 deg.C, and ultrasonic dispersing. And after the components in the solution are uniformly dispersed, reducing the temperature of the solution to 30-60 ℃ to obtain a solution B.

3) Adding the solution A into the solution B, fully stirring, and simultaneously performing ultrasonic dispersion. Throughout the process, the temperature was maintained at 30 ℃ to 60 ℃ to give solution C.

4) And adding a curing agent into the solution C, and then fully stirring to obtain the conductive coating slurry.

In particular, the positive electrode current collector can be prepared according to the following steps:

the conductive coating paste is first coated on both sides of the polymer layer opposite to each other using an extrusion coater to a coating thickness of 1 to 10 μm, preferably 1 to 5 μm, and then dried at 70 ℃ for 0.5 to 3 hours to prepare the positive electrode current collector.

The positive electrode coating in the embodiment of the present invention is described below.

In the embodiment of the invention, the positive coating slurry of the positive coating can be formed by mixing a positive active material, a conductive agent, a binder and a solvent. The positive electrode active material may be lithium cobaltate, and the conductive agent, the binder, and the solvent may be determined according to the description of the conductive agent, the binder, and the solvent, which is not described herein again. Preferably, the conductive agent may be a conductive carbon nanotube, the binder is polyvinylidene fluoride, and the solvent may be N-methylpyrrolidone NMP solvent.

In specific implementation, the positive plate can be prepared according to the following steps:

1) lithium cobaltate is used as an anode active material, a conductive carbon nano tube is used as a conductive agent, polyvinylidene fluoride is used as a bonding agent, the materials are added into a stirring tank according to the mass ratio of 97.2:1.5:1.3, then an N-methyl pyrrolidone NMP solvent is added, the materials are fully stirred according to the batching process in the prior art, and the materials are filtered through a 200-mesh screen to prepare anode slurry, wherein the solid content of the anode slurry is 70-75%.

2) And coating the slurry on the positive current collector by using a coating machine. And then drying at 120 ℃ to obtain the positive plate.

The preparation method of the positive plate provided by the embodiment of the invention is different from the preparation method of the positive plate which is prepared by taking an aluminum foil as a positive current collector of the positive plate, taking a polymer layer coated with a conductive coating as the positive current collector of the positive plate and then coating positive coating slurry on the positive current collector. The conductivity between the anode particles in the anode coating can be ensured through the conductive coating, and the contact between the aluminum foil and the cathode active material can be effectively avoided due to the reduction of the use of the aluminum foil, so that the risk of internal short circuit is reduced.

Optionally, the forming a first substrate comprises:

forming a polymer layer;

coating ceramic coating slurry on two opposite side surfaces of the polymer layer and drying to obtain the first base material, wherein the ceramic coating slurry is formed by mixing ceramic and a solvent;

coat conductive coating thick liquids in on two sides that first substrate is carried on the back mutually and dry, obtain anodal mass flow body, include:

and coating the conductive coating slurry on the side surface of the ceramic coating, which is opposite to the polymer layer, and drying to obtain the anode current collector.

In this embodiment, in the preparation of the positive electrode current collector, a layer of ceramic coating slurry may be coated on two opposite sides of the polymer layer, and a ceramic coating is formed after drying. The existence of the ceramic coating can effectively increase the heat shrinkage resistance of the polymer layer and prevent the polymer layer from generating heat shrinkage in the high-temperature baking process. And then coating the conductive coating slurry on the ceramic coating to obtain the positive current collector.

The ceramic coating in the embodiment of the present invention is described below.

In the embodiment of the invention, the ceramic coating slurry of the ceramic coating can be formed by mixing ceramic particles, a binder, a thickening agent, a dispersing agent and the like with a solvent. Wherein the ceramic particles may comprise one or more of alumina, magnesia, silica, titania, zirconia, zinc oxide, barium sulfate, boron nitride, aluminum nitride, magnesium nitride, tin dioxide, magnesium hydroxide, boehmite, or calcium carbonate. The median diameter D50 of the ceramic particles may be 0.1 to 11 μm, preferably 0.5 to 3 μm.

The binder may include one or more selected from styrene-butadiene rubber, polyvinylidene fluoride-trifluoroethylene, polyvinylidene fluoride-tetrafluoroethylene, polyvinylidene fluoride-hexafluoroethylene, polyvinylidene fluoride-hexafluoropropylene, styrene-acrylic emulsion, polyethylacrylate, polymethyl methacrylate, polybutyl methacrylate, polyvinyl alcohol, ethylene-vinyl acetate copolymer, polyvinyl acetate, polyurethane.

The dispersant may include one or more of fluoroalkyl methoxy alcohol ether, polyoxyethylene alkylamine, sodium butylnaphthalene sulfonate, sodium arylnaphthalene sulfonate, sodium dodecylbenzene sulfonate, sodium alkyl sulfate, sodium polyacrylate, sodium polymetaphosphate, sodium silicate, and sodium dodecyl sulfate.

The thickener may be sodium carboxymethyl cellulose and/or lithium carboxymethyl cellulose.

In specific implementation, a certain amount of deionized water can be taken, a certain amount of dispersing agent is added, and a certain amount of ceramic particles are added at the same time to prepare slurry containing ceramics, wherein the mass percentage of the dispersing agent can be 0.2-10%, and the mass percentage of the ceramic particles can be 30-70%; and then adding 1 to 10 mass percent of binder and 1 to 10 mass percent of thickener into the ceramic-containing slurry to obtain the ceramic slurry with the solid content of 32.2 to 60 percent.

Thereafter, the positive electrode collector may be prepared as follows:

1) the ceramic coating slurry is first coated on the opposite sides of the polymer layer using an extrusion coater, which may be 1 to 10 μm, preferably 1 to 5 μm, in thickness, and dried.

2) The positive electrode current collector is prepared by coating the conductive coating slurry on the surface of the ceramic coating layer to a thickness of 1 to 10 μm, preferably 1 to 5 μm, and then drying at 70 ℃ for 0.5 to 3 hours.

The following are 5 specific examples of the present invention and 1 comparative example:

example 1

Step one, preparing ceramic coating slurry.

Specifically, a certain amount of deionized water is taken, and a certain amount of sodium polyacrylate is added as a dispersing agent, wherein the dispersing agent accounts for 1% of the mass. Meanwhile, a certain amount of ceramic (alumina) is added, the ceramic accounts for 45 percent of the mass ratio, and the ceramic-containing slurry is prepared. Then, 5% by mass of polyvinylidene fluoride as a binder and 8% by mass of sodium methyl cellulose as a thickener were added to the above ceramic-containing slurry to obtain a ceramic coating slurry having a solid content of 59%.

And step two, preparing conductive coating slurry.

Specifically, the components are respectively weighed according to a preset ratio for later use, wherein the preset ratio comprises 30 parts of a conductive agent (carbon nano tube), 1.5 parts of a dispersing agent (sodium polyacrylate), 5 parts of a binder (acrylic emulsion), 1 part of a thermal stability (2, 6-tert-butyl-4-methyl phenol) agent, 50 parts of a tackifier (polyacrylic resin), 1 part of a curing agent (diphenylmethane diisocyanate) and 100 parts of a solvent (acetone).

1) Adding 50% of solvent into conductive agent and dispersant, stirring thoroughly, and ultrasonic dispersing. Then, a binder is added to the above solution, and sufficient stirring is performed while ultrasonic dispersion is performed. Thereafter, the above solution was heated to 45 ℃ to obtain a solution A.

2) Adding tackifier and heat stabilizer into the rest 50% of solvent, stirring at 80 deg.C, and ultrasonic dispersing. And after the components in the solution are uniformly dispersed, reducing the temperature of the solution to 45 ℃ to obtain a solution B.

3) Adding the solution A into the solution B, fully stirring, and simultaneously performing ultrasonic dispersion. Throughout the process, the temperature was maintained at 45 ℃ to give a solution C.

4) And adding a curing agent into the solution C, and then fully stirring to obtain the conductive coating slurry. The conductive coating paste had a viscosity of 4700cps at 25 ℃ and a solid content of 47.3%.

And step three, preparing the positive current collector.

Specifically, the ceramic coating slurry prepared in the first step is coated on two opposite side surfaces of a polyethylene single-layer base film (with the thickness of 5 microns) with the coating thickness of 1 micron by using an extrusion coating machine, and then dried. And then, coating the conductive coating slurry prepared in the second step of coating the surface of the ceramic coating to a thickness of 1 μm. And finally, drying at 70 ℃ for 0.5 to 3 hours to prepare the positive current collector.

And step four, preparing the anode coating slurry.

Specifically, lithium cobaltate is used as an anode active material, a conductive carbon nano tube is used as a conductive agent, polyvinylidene fluoride is used as a binder, the mixture is added into a stirring tank according to the mass ratio of 97.2:1.5:1.3, an N-methylpyrrolidone NMP solvent is added, the mixture is fully stirred according to the batching process in the prior art, and is filtered through a 200-mesh screen to prepare anode slurry, wherein the solid content of the anode slurry is 70-75%.

And step five, preparing the positive plate.

Specifically, the coating slurry of the positive electrode prepared in the fourth step is coated on the current collector of the positive electrode prepared in the third step by using a coating machine. And then drying at 120 ℃ to obtain the positive plate. To unipolar ear positive plate, as shown in fig. 1, unipolar ear positive plate's the last side of positive coating's left side edge, the positive current collector's left side edge flushes with the positive coating's of downside left side edge, and goes up the positive coating of side and be good at the positive coating of downside, and on the positive coating of downside was located in pasting of gummed paper part, on the positive current collector was located in pasting of part, gummed paper's length was: the length of the anode coating on the upper side surface-the length of the anode coating on the lower side surface is +7mm, the left end of the adhesive tape covers the anode coating on the lower side surface by 2mm, and the right end of the adhesive tape exceeds the anode coating on the upper side surface by 5 mm. For the double-pole-lug positive plate, as shown in fig. 4, an empty foil area is arranged on the left side of the double-pole-lug positive plate, the empty foil area can be used for arranging the positive pole lug, and the length of the empty foil area in the horizontal direction is 8 mm. The left side edge of the positive coating on the upper side is flush with the left side edge of the positive coating on the lower side, and the positive coating on the upper side is longer than the positive coating on the lower side. On the positive coating of downside was located in the subsides of gummed paper partly, partly subsides were located on the anodal mass flow body, the length of gummed paper is: the length of the anode coating on the upper side surface-the length of the anode coating on the lower side surface is +7mm, the left end of the adhesive tape covers the anode coating on the lower side surface by 2mm, and the right end of the adhesive tape exceeds the anode coating on the upper side surface by 5 mm.

And step six, preparing the cathode coating slurry.

Specifically, artificial graphite is used as a negative electrode active material, conductive carbon black is used as a conductive agent, styrene butadiene rubber is used as a binder, and sodium carboxymethyl cellulose is used as a thickening agent, the artificial graphite is added into a stirring tank according to the mass ratio of 96.9:1.5:1.3:13, a deionized water solvent is added, the materials are fully stirred according to the batching process in the prior art, and the materials are filtered through a 150-mesh screen to prepare negative electrode coating slurry, wherein the solid content of the negative electrode slurry is 40-45%.

Step seven, preparing the negative plate

And coating the slurry of the negative electrode coating prepared in the sixth step on copper foil by using a coating machine, and drying at the temperature of 100 ℃ to obtain the negative electrode sheet. And an empty foil area is arranged on the left side of the negative plate, and the empty foil area can be used for arranging negative electrode tabs. The length of the empty foil area in the horizontal direction is 8 mm. And a single-side paste coating area with a negative coating coated on the lower side and a negative coating not coated on the upper side is arranged at the rightward extending end of the negative plate, the length of the single-side paste coating area in the horizontal direction is 5mm, and then the single-side paste coating area is a double-side paste coating area with the negative coating coated on the upper side and the lower side.

And step eight, assembling the battery.

Aiming at the single positive tab battery, the assembly steps are as follows:

1) and (3) taking a cylindrical battery metal shell, uniformly coating the conductive coating slurry in the metal shell, and drying at 70 ℃ for 0.5 to 3 hours.

2) And winding the positive plate prepared in the fifth step and the negative plate prepared in the seventh step together with the diaphragm sheet to form a wound battery cell. As shown in fig. 3, the outermost side of the wound battery cell is the positive electrode current collector at the tail of the positive electrode plate, and this part of the positive electrode current collector will be wound around the periphery of the wound battery cell for one and a half circles. After the winding is completed, the portion of the positive electrode collector may be folded back by a portion.

3) And (3) transferring the winding battery cell into the cylindrical battery metal shell, so that the outer ring of the winding battery cell is in close contact with the inner wall of the metal shell, and the bent part is also in close contact with the inner wall of the metal shell, thereby ensuring the conductivity of the winding battery cell.

4) And welding the negative electrode tab of the negative electrode plate with a bottom cover to serve as the negative electrode tab of the battery. And an insulating pad is arranged in the bottom cover to ensure that the bottom cover is insulated from the cylindrical battery metal shell, and electrolyte is injected after the bottom cover is baked to remove moisture. The electrolyte can be prepared according to the following steps: in a solvent in which propylene carbonate PC, ethylene carbonate EC, dimethyl carbonate DMC and ethyl methyl carbonate EMC are mixed in a weight ratio of about 1:1:0.5:1, lithium hexafluorophosphate LiPF6 is added and mixed uniformly, wherein the concentration of lithium hexafluorophosphate LiPF6 is about 1mol/L, and the electrolyte can be obtained by mixing uniformly.

5) And directly welding the top cover and the metal shell of the cylindrical battery together to form a positive electrode, thus assembling the battery provided by the embodiment of the invention.

Aiming at the double-positive-lug battery, the assembling steps are as follows:

2) And winding the positive plate prepared in the fifth step and the negative plate prepared in the seventh step together with the diaphragm sheet to form a wound battery cell. As shown in fig. 7, the outermost side of the wound battery cell is the positive electrode current collector at the tail of the positive electrode plate, and this part of the positive electrode current collector will be wound around the periphery of the wound battery cell for one and a half turns. After the winding is completed, the portion of the positive electrode collector may be folded back by a portion.

3) And the winding battery core is shifted into the cylindrical battery metal shell, so that the outer ring of the winding battery core is in close contact with the inner wall of the metal shell, and the bent part is also in close contact with the inner wall of the metal shell, so that the conductivity of the winding battery core is ensured and the winding battery core is used as a first positive lug.

4) And welding the negative electrode tab of the negative electrode plate with a bottom cover to serve as the negative electrode tab of the battery. And an insulating pad is arranged in the bottom cover to ensure that the bottom cover is insulated from the cylindrical battery metal shell, and electrolyte is injected after the bottom cover is baked to remove moisture. The electrolyte can be prepared according to the following steps: in a solvent in which propylene carbonate PC, ethylene carbonate EC, dimethyl carbonate DMC and ethyl methyl carbonate EMC are mixed in a weight ratio of about 1:1:0.5:1, lithium hexafluorophosphate LiPF6 is added and mixed uniformly, wherein the concentration of lithium hexafluorophosphate LiPF6 is about 1mol/L, and the electrolyte can be obtained by mixing uniformly. The positive tab is then electrically connected to the top cap as a second positive tab.

5) And directly welding the top cover and the cylindrical battery metal shell together to form a total positive lug, thus assembling the battery provided by the embodiment of the invention.

Example 2

Example 2 is different from example 1 in that the single layer coating thickness of the ceramic coating layer is controlled to 2 μm and the single layer coating thickness of the conductive coating layer is controlled to 1 μm in step three.

Other steps may refer to the specific description in embodiment 1, and are not described herein again in order to avoid repetition.

Example 3

Example 3 is different from example 1 in that the single layer coating thickness of the ceramic coating layer was controlled to 3 μm and the single layer coating thickness of the conductive coating layer was controlled to 1 μm in step three.

Example 4

Example 4 is different from example 1 in that the single layer coating thickness of the ceramic coating layer is controlled to 2 μm and the single layer coating thickness of the conductive coating layer is controlled to 2 μm in step three.

Example 5

Example 5 is different from example 1 in that the single layer coating thickness of the ceramic coating layer was controlled to 2 μm and the single layer coating thickness of the conductive coating layer was controlled to 3 μm in step three.

Comparative example 1

Step one, preparing anode coating slurry and an anode plate.

The positive electrode coating slurry was coated on an aluminum foil substrate using a coater. And then drying at 120 ℃ to obtain the conventional positive plate. In this comparative example, an empty foil area was provided on the left side of the conventional positive electrode sheet, the empty foil area being usable for providing the positive electrode tab, and the empty foil area having a length of 8mm in the horizontal direction. The left side edge of the positive coating on the upper side is flush with the left side edge of the positive coating on the lower side, and the positive coating on the upper side is longer than the positive coating on the lower side. The conventional positive plate is provided with a double-sided pasting area, the upper side face and the lower side face of which are both coated with positive coating, a single-sided pasting area, the upper side face of which is coated with the positive coating and the lower side face of which is not coated with the positive coating, and an exposed area, the two sides of which are not coated with the positive coating, at the rightward extending end of the conventional positive plate, wherein the length of the exposed area in the horizontal direction is 12 mm.

And step two, preparing the cathode coating slurry and the cathode sheet.

Specifically, artificial graphite is used as a negative electrode active material, conductive carbon black is used as a conductive agent, styrene butadiene rubber is used as a binder, and sodium carboxymethyl cellulose is used as a thickening agent, the artificial graphite is added into a stirring tank according to the mass ratio of 96.9:1.5:1.3:13, a deionized water solvent is added, the materials are fully stirred according to the batching process in the prior art, and the materials are filtered through a 150-mesh screen to prepare negative electrode coating slurry, wherein the solid content of the negative electrode slurry is 40-45%. And coating the prepared negative coating slurry on a copper foil substrate by using a coating machine, and drying at the temperature of 100 ℃ to obtain the negative plate. In this comparative example, a blank foil region was provided on the left side of the conventional negative electrode sheet, which can be used to provide the negative electrode tab. The length of the empty foil area in the horizontal direction is 8 mm. A single-sided pasting area with a negative electrode coating coated on the lower side and a negative electrode coating not coated on the upper side is arranged at the rightwards extending end of the conventional negative electrode plate, the length of the single-sided pasting area in the horizontal direction is 5mm, and then a double-sided pasting area with the negative electrode coating coated on the upper side and the lower side is arranged.

And step three, assembling the battery.

2) And winding the positive plate prepared in the step one and the negative plate prepared in the step two together with the diaphragm sheet to form a wound battery cell.

3) Transferring the wound battery core into the cylindrical battery metal shell, welding a negative electrode lug of the negative electrode plate with a bottom cover to serve as the negative electrode lug of the battery, arranging an insulating pad in the bottom cover to ensure that the bottom cover is insulated from the cylindrical battery metal shell, and injecting electrolyte after baking to remove moisture; and welding the positive lug of the positive plate with the top cover of the cylindrical lithium ion battery to serve as a positive electrode, and arranging an insulating pad inside the top cover to ensure that the top cover is insulated from the metal shell of the cylindrical battery, so that the battery in the comparative example is assembled.

The electrolyte can be prepared according to the following steps: in a solvent in which propylene carbonate PC, ethylene carbonate EC, dimethyl carbonate DMC and ethyl methyl carbonate EMC are mixed in a weight ratio of about 1:1:0.5:1, lithium hexafluorophosphate LiPF6 is added and mixed uniformly, wherein the concentration of lithium hexafluorophosphate LiPF6 is about 1mol/L, and the electrolyte can be obtained by mixing uniformly.

The batteries of examples 1 to 5 and comparative example 1 described above were subjected to a nail penetration test and a cycle life test, respectively. The nail penetration testing method comprises the following steps: and (3) placing the battery in a normal temperature environment, charging the battery to a voltage of 4.45V at a constant current of 1C, then charging the battery at a constant voltage until the current is reduced to 0.025C, and stopping charging. A steel nail with a diameter of 4mm was used to vertically pass through the center of the cell at a speed of 30mm/s for 300 seconds. If the battery does not ignite and explode, it can be recorded as pass. 10 lithium ion batteries are tested each time, and the passing rate of the nail penetration test is used as an index for evaluating the safety of the batteries.

The cycle life testing method comprises the following steps: the battery is placed in a normal temperature environment, the battery is charged at a constant current of 1C until the voltage is 4.45V, then the battery is charged at a constant voltage until the current is reduced to 0.05C, the charging is stopped, and then the battery is discharged to 3.0V at 1C for circulation.

Finally, the results of the safety tests are summarized in tables 1 and 2, where table 1 is the test result of the single-tab battery, and table 2 is the test result of the double-tab battery. Among them, the puncture passage rate was higher in examples 1 to 5, and almost all passed, compared to comparative example 1, and the safety performance of the battery was significantly improved. At the same time, the cycle life is basically equivalent without attenuation. In addition, the charging speed is significantly increased.

Table 1 comparative example test results for different examples of single positive ear cells

Sample (I)	Penetration rate of acupuncture	Capacity retention rate of 1000T
			Example 1	9/10	84.27％
Example 2	10/10	83.63％
			Example 3	10/10	83.93％
Example 4	9/10	84.37％
			Example 5	10/10	85.72％
Comparative example 1	0/15	85.21％

Table 2 comparative example test results for different examples of double positive tab cells

Sample (I)	Penetration rate of acupuncture	Charging speed	100% S0C	Capacity retention rate of 1000T
					Example 1	10/10	87.3min	80.93％
Example 2	9/10	87.9min	80.67％
				Example 3	10/10	88.1min	80.02％
Example 4	10/10	87.3min	81.54％
				Example 5	10/10	86.9min	82.36％
Comparative example 1	0/15	96.2min	80.37％

It should be noted that, various optional implementations described in the embodiments of the present invention may be implemented in combination with each other or implemented separately, and the embodiments of the present invention are not limited thereto.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "left", "right", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation and a specific orientation configuration and operation, and thus, should not be construed as limiting the present invention. Furthermore, "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be directly connected or indirectly connected through an intermediate member, or they may be connected through two or more elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The embodiments described above are described with reference to the drawings, and various other forms and embodiments are possible without departing from the principle of the present invention, and therefore, the present invention should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of components may be exaggerated for clarity. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. The terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, components, and/or components, but do not preclude the presence or addition of one or more other features, integers, components, and/or groups thereof. Unless otherwise indicated, a range of values, when stated, includes the upper and lower limits of the range and any subranges therebetween.

While the preferred embodiments of the present invention have been described, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.

Claims

1. The positive plate is characterized by comprising a positive current collector and a positive coating, wherein the positive current collector comprises a first base material and a conductive coating, the conductive coating is arranged on two opposite side surfaces of the first base material, and the first base material comprises a polymer layer; the positive current collector comprises a first side face and a second side face which are opposite, and the positive coating is arranged on at least one of the first side face and the second side face.

2. The positive electrode sheet according to claim 1, wherein the first substrate further comprises a ceramic coating layer disposed on opposite sides of the polymer layer, the conductive coating layer being disposed on a side of the ceramic coating layer opposite the polymer layer.

3. The positive electrode sheet according to claim 1, wherein the positive electrode coating is disposed on each of the first and second sides, the positive electrode current collector includes first and second opposite ends, the positive electrode coating on the first side includes first and second opposite edges, the first edge is adjacent to the first end, and the second edge is adjacent to the second end; the positive electrode coating of the second side includes opposing third and fourth edges, the third edge being proximate the first end and the fourth edge being proximate the second end; the first side comprises a first area between the second edge and the second end, the second side comprises a second area between the fourth edge and the second end; the first region and the second region are not provided with the positive electrode coating.

4. The positive electrode sheet according to claim 3, wherein the length of the first region is smaller than the length of the second region.

5. The positive plate according to claim 4, further comprising a piece of adhesive tape, wherein a portion of the adhesive tape is attached to the positive coating layer on the second side surface, another portion of the adhesive tape is attached to the second region, the length of the adhesive tape attached to the second region is greater than or equal to the circumference of the first winding layer, and the first winding layer is a winding layer where the adhesive tape is located after the positive plate is wound.

6. The positive tab of claim 3, further comprising a positive tab, the first side comprising a third region between the first edge and the first end, the second side comprising a fourth region between the third edge and the first end; the third area and the fourth area are not provided with the anode coating, and the anode tab is in contact with the third area and the fourth area.

7. The positive plate according to claim 6, wherein the positive tab comprises a first extension and a second extension, the first extension and the second extension forming an angle of less than 180 °; the first extension portion is disposed in one of the third region and the fourth region, the second extension portion is disposed in the other of the third region and the fourth region, and the first extension portion and the second extension portion are electrically connected.

8. A battery, characterized by, including electric core and shell, the electric core set up in the shell, the electric core is coiled after positive plate and negative pole piece are laminated in proper order and formed, be equipped with the diaphragm piece between any adjacent one positive plate and one negative pole piece, positive plate is according to any claim 1 to 7 any positive plate.

9. The battery of claim 8, wherein the housing is a conductive shell; the first side surface and the second side surface are both provided with the anode coatings, and the anode current collector comprises a first end and a second end which are opposite; the positive electrode coating of the first side includes opposing first and second edges, the first edge being proximate the first end and the second edge being proximate the second end, the first side including a first region, the first region being located between the second edge and the second end; the positive coating of the second side includes opposing third and fourth edges, the third edge being proximate the first end, the fourth edge being proximate the second end, the second side including a second region, the second region being located between the fourth edge and the second end; the first area and the second area are not provided with the anode coating, and the second area is attached to the inner wall of the shell.

10. The battery of claim 9, wherein the second end is bent in a first direction to form a bent portion, the first direction is opposite to a winding direction of the battery core, the bent portion includes a first sub-region and a second sub-region opposite to each other, the first region includes the first sub-region, the second region includes the second sub-region, and the first sub-region is attached to the inner wall of the housing.