Battery cell and electric device

Abstract

The invention discloses a battery cell and a power utilization device, the battery cell comprises a shell and an electrode assembly, the shell forms a containing cavity filled with electrolyte, the electrode assembly is arranged in the containing cavity, and the surface, away from a first current collector, of an active substance layer of a first pole piece in the electrode assembly is sunken inwards to form a groove; the end part of the groove in the extension direction is communicated with the edge of the first pole piece, the first pole piece comprises a first edge and a second edge which are connected, and an included angle C between the extension direction of the groove and the first edge is more than or equal to 5 degrees and less than or equal to 85 degrees; the included angle between the extending direction of the groove and the second edge is E, and E is larger than or equal to 5 degrees and smaller than or equal to 85 degrees. When the electrolyte flows along the groove, corresponding displacement can be decomposed in the extension direction of the first edge and the extension direction of the second edge, so that the electrolyte can well infiltrate the interior of the electrode assembly, the electrolyte in the electrode assembly can be supplemented in time in the circulation process, and the service life of the electrode assembly is prolonged. And the cycle life of the battery cell is prolonged.

Description

Technical Field

[0001] The present application relates to the field of batteries, and particularly to an electrode core and an electrical device using the same. Background Art

[0002] A rechargeable battery, which can also be called a secondary battery, refers to a battery that can be reused by activating the active substances through charging after discharging. Rechargeable batteries are widely used in electronic devices such as mobile phones, laptop computers, battery cars, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and electric tools, etc.

[0003] With the development of science and technology and industrial technology, batteries have gradually become a bottleneck for electronic and electrical devices. How to improve the cycle life of secondary batteries has always attracted the attention of those skilled in the art. Summary of the Invention

[0004] The present application provides an electrode core and an electrical device using the same, and the electrode core has a long cycle life.

[0005] In a first aspect, the present application provides an electrode core, which includes a housing and an electrode assembly. The housing forms a cavity filled with an electrolyte; the electrode assembly is disposed in the cavity and includes a plurality of first electrode sheets stacked along the thickness direction. Each first electrode sheet includes a first current collector and an active material layer. The first current collector includes two first surfaces oppositely disposed along the thickness direction, and at least one of the first surfaces is provided with an active material layer. The surface of the active material layer away from the first current collector is recessed inward to form a groove, and the end of the groove in the extending direction communicates with the edge of the first electrode sheet; the first electrode sheet includes a connected first edge and a second edge, the included angle between the extending direction of the groove and the first edge is C, and 5° ≤ C ≤ 85°; the included angle between the extending direction of the groove and the second edge is E, and 5° ≤ E ≤ 85°.

[0006] In the above structure, since the groove in the active material layer communicates with the edge of the first pole piece, and the range of the angle C between the extending direction of the groove and the first edge is 5° ≤ C ≤ 85°, and the range of the angle E between the extending direction of the groove and the second edge is 5° ≤ E ≤ 85°, the groove is inclined with respect to two adjacent edges in the first pole piece. The extending direction of the groove has components in the extending direction of the first edge and in the extending direction of the second edge adjacent to the first edge. When the electrolyte flows along the groove, corresponding displacements can be decomposed in the extending direction of the first edge and in the extending direction of the second edge, rather than having a displacement only at a certain edge. This enables the groove to drain the electrolyte while taking into account the extending directions of two adjacent edges. When the electrolyte in the cavity flows into the electrode assembly from the edge of the outer periphery of the first pole piece under the guidance of the groove, the electrolyte can better infiltrate the inside of the electrode assembly, which is beneficial to timely supplement the electrolyte inside the electrode assembly during the cycle process and is beneficial to extending the cycle life of the battery cell.

[0007] For the battery cell provided by some embodiments of the present application, the first edge and the second edge form a first corner. The first pole piece includes a diagonal line passing through the first corner. The angle between the diagonal line and the first edge is A, and the angle between the diagonal line and the second edge is B, where A ≥ B. The angle between the extending direction of the groove and the first edge is C, and A + 5° ≤ C ≤ A + 40°. When the electrolyte flows along the groove, the corresponding distances decomposed in the extending direction of the first edge and in the extending direction of the second edge are relatively close. This enables the electrolyte infiltrating into the electrode assembly along the groove introduced from the first edge and the second edge to reach the inner region of the electrode assembly at a closer time, enabling the groove to more uniformly supply the electrolyte from the cavity around the electrode assembly to the inside of the electrode assembly. The groove can not only improve the wettability of the electrolyte to the electrode assembly but also improve the uniformity of the utilization of the electrolyte.

[0008] For the battery cell provided by some embodiments of the present application, A + 15° ≤ C ≤ A + 35°. This enables the electrolyte infiltrating into the electrode assembly along the groove introduced from the first edge and the second edge to reach the inner region of the electrode assembly at a closer time, and at the same time, it can more uniformly supply the electrolyte from the cavity around the electrode assembly to the inside of the electrode assembly. The groove can not only improve the wettability of the electrolyte to the electrode assembly but also improve the uniformity of the utilization of the electrolyte.

[0009] According to the battery cell provided by some embodiments of the present application, the first electrode tab includes a first part and a second part connected to each other. Both the first part and the second part are configured to be rectangular, and the first corner is located in the first part or the second part; in the first part and the second part, the average angle between all the diagonals and the first edge is V, and V + 15° ≤ C ≤ V + 35°, so that the first part and the second part can be connected to each other according to the actual situation to form the first electrode tab with a specific shape required for the electrode assembly.

[0010] According to the battery cell provided by some embodiments of the present application, the groove extends along a first direction, and the first direction is perpendicular to the thickness direction; along the first direction, the length of the groove is L, and the length of the first electrode tab is N. So that the groove can guide the electrolyte to the central position of the first electrode tab in the first direction, so that the central position of the first electrode tab can be replenished with electrolyte in time.

[0011] According to the battery cell provided by some embodiments of the present application, the groove penetrates the active material layer along the first direction, so that the electrolyte in the cavity can enter the groove from both ends in the extending direction of the groove, so that more electrolyte can flow into the groove, which can increase the amount of electrolyte guided by the groove and is beneficial to reducing the occurrence of the lack of electrolyte inside the electrode assembly.

[0012] According to the battery cell provided by some embodiments of the present application, there are a plurality of grooves, the plurality of grooves are arranged at intervals, and the extending directions of at least two grooves intersect.

[0013] According to the battery cell provided by some embodiments of the present application, the groove includes a first groove and a second groove. The first groove extends along the first direction, and there are a plurality of first grooves arranged at intervals along a second direction. The second direction, the thickness direction and the first direction are perpendicular to each other; the extending direction of the second groove intersects with the extending direction of the first groove.

[0014] According to the battery cell provided by some embodiments of the present application, the interval between two adjacent first grooves in the second direction is H, and 100 μm ≤ H ≤ 5000 μm.

[0015] According to the battery cell provided by some embodiments of the present application, 400 μm ≤ H ≤ 2500 μm.

[0016] According to the battery cell provided by some embodiments of the present application, the width of the opening of the groove in the second direction is J, and 40 μm ≤ J ≤ 250 μm.

[0017] According to the battery cell provided by some embodiments of the present application, 50 μm ≤ J ≤ 200 μm.

[0018] According to the battery cell provided by some embodiments of the present application, in the thickness direction, the depth of the groove is K, and the thickness of the active material layer is M.

[0019] According to the battery cell provided by some embodiments of the present application, in the thickness direction, the depth of the groove is K, and 4 μm ≤ K ≤ 45 μm.

[0020] According to the battery cell provided by some embodiments of the present application, 5 μm ≤ K ≤ 40 μm.

[0021] According to the battery cell provided by some embodiments of the present application, the groove is formed by laser grooving or chemical etching.

[0022] According to the battery cell provided by some embodiments of the present application, the cross-sectional shape of the groove is one of a triangle, a trapezoid, a semi-circle, and a rectangle.

[0023] According to the battery cell provided by some embodiments of the present application, the first electrode sheet is a negative electrode sheet.

[0024] In a second aspect, some embodiments of the present application provide an electrical device, which includes the battery cell provided by any of the above technical solutions, and the battery cell is used to provide electrical energy.

[0025] The technical solutions provided by the embodiments of the present disclosure at least bring the following beneficial effects:

[0026] The present application provides an electric cell, which includes a housing and an electrode assembly. The housing forms a cavity filled with an electrolyte, and the electrode assembly is disposed in the cavity. The electrode assembly includes a plurality of first electrode plates stacked along the thickness direction. The first electrode plate includes a first current collector and an active material layer. The first current collector includes two first surfaces oppositely disposed along the thickness direction, and the active material layer is disposed on at least one of the first surfaces. The surface of the active material layer away from the first current collector is recessed inward to form a groove, and the end of the groove in the extending direction communicates with the edge of the first electrode plate; the first electrode plate includes a connected first edge and a second edge, and the included angle between the extending direction of the groove and the first edge is C, where 5° ≤ D ≤ 85°; the included angle between the extending direction of the groove and the second edge is E, where 5° ≤ E ≤ 85°. In the above structure, since the groove in the active material layer communicates with the edge of the first electrode plate, and the range of the included angle C between the extending direction of the groove and the first edge is 5° ≤ C ≤ 85°, and the range of the included angle E between the extending direction of the groove and the second edge is 5° ≤ E ≤ 85°, the groove is inclined with respect to two adjacent edges in the first electrode plate. The extending direction of the groove has components in the extending direction of the first edge and in the extending direction of the second edge adjacent to the first edge. When the electrolyte flows along the groove, corresponding displacements can be decomposed in the extending direction of the first edge and in the extending direction of the second edge, rather than only having a displacement at a certain edge. This enables the groove to drain the electrolyte while taking into account the extending directions of two adjacent edges. When the electrolyte in the cavity flows into the electrode assembly from the edge of the outer periphery of the first electrode plate under the guidance of the groove, the electrolyte can better infiltrate the inside of the electrode assembly, which is beneficial to timely supplement the electrolyte inside the electrode assembly during the cycle and is beneficial to extending the cycle life of the electric cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The features, advantages, and technical effects of exemplary embodiments of the present application will be described below with reference to the drawings.

[0028] Figure 1 Schematic structural diagram of an electric cell provided by an embodiment of the present application;

[0029] Figure 2 Cross-sectional view of an electrode assembly provided by an embodiment of the present application;

[0030] Figure 3 Top view of a first electrode plate provided by the first embodiment of the present application;

[0031] Figure 4 Top view of a first electrode plate provided by the second embodiment of the present application;

[0032] Figure 5 Top view of a first electrode plate provided by the third embodiment of the present application;

[0033] Figure 6 The top view of the first pole piece provided by the fourth embodiment of the present application;

[0034] Figure 7 The top view of the first pole piece provided by the fifth embodiment of the present application;

[0035] Figure 8 The top view of the first pole piece provided by the sixth embodiment of the present application;

[0036] Figure 9 The cross-sectional view of the first pole piece provided by some embodiments of the present application.

[0037] In the figure:

[0038] 1. Housing; 2. Cavity; 3. Electrode assembly; 31. First pole piece; 311. First current collector; 3111. First surface; 312. Active material layer; 313. Groove; 3131. First groove; 3132. Second groove; 314. First edge; 315. Second edge;

[0039] 33. Positive pole piece; 34. Negative pole piece; X. Thickness direction; Y. First direction; Z. Second direction.

[0040] In the drawings, the drawings are not necessarily drawn to actual scale. Detailed implementation manners

[0041] To make the objectives, 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 accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some but not all of the embodiments of the present application.

[0042] Currently, from the perspective of the development of the market situation, the application of batteries is becoming more and more extensive. Batteries are not only applied to energy storage power systems such as hydraulic, thermal, wind and solar power stations, but also widely used in electric transportation means such as electric bicycles, electric motorcycles, electric vehicles, as well as in multiple fields such as military equipment and aerospace.

[0043] The battery cells mentioned in the embodiments of the present application can be secondary batteries or primary batteries. A secondary battery refers to a battery that can be activated by charging after discharging so as to continue to be used.

[0044] The battery cells can be lithium-ion battery cells, sodium-ion battery cells, sodium-lithium-ion battery cells, lithium metal battery cells, sodium metal battery cells, lithium-sulfur battery cells, magnesium-ion battery cells, nickel-metal hydride battery cells, nickel-cadmium battery cells, lead-acid battery cells, etc.

[0045] A battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of the battery cell, active ions (such as lithium ions) are embedded and extracted back and forth between the positive electrode and the negative electrode. The separator is disposed between the positive electrode and the negative electrode, which can prevent the short circuit between the positive and negative electrodes and allow the active ions to pass through at the same time.

[0046] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), etc.

[0047] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, or a battery cell of other shapes. The prismatic battery cell includes a square shell battery cell, a blade-shaped battery cell, and a multi-prismatic battery cell. The multi-prismatic battery cell is, for example, a hexagonal prism battery cell, etc.

[0048] The electrolyte plays a very important role during the operation of the battery cell. During the cyclic use of the battery cell, the electrolyte is continuously consumed. Since there is a gap between the electrode assembly and the housing in the battery cell, the area of the electrode assembly close to the outside can contact the electrolyte in the gap, and the infiltrated electrolyte is relatively sufficient. However, after the electrolyte is consumed, the internal area of the electrode assembly far from the outside needs the surrounding electrolyte to be transported to the inside of the electrode assembly for replenishment. If the transport capacity of the electrolyte is insufficient, it will cause the lack of liquid inside the battery cell, ultimately leading to a rapid decay of the battery cell capacity and a serious shortening of the cycle life.

[0049] Based on the above considerations, in order to improve the cycle life of the battery cell, the present application provides a battery cell, which includes a housing and an electrode assembly. The housing forms a cavity filled with electrolyte, and the electrode assembly is disposed in the cavity. The electrode assembly includes a plurality of first electrode sheets stacked along the thickness direction. The first electrode sheet includes a first current collector and an active material layer. The first current collector includes two first surfaces disposed opposite to each other along the thickness direction. An active material layer is provided on at least one of the first surfaces. The surface of the active material layer away from the first current collector is recessed inward to form a groove, and the end of the groove in the extending direction communicates with the edge of the first electrode sheet; the first electrode sheet includes a connected first edge and a second edge, and the included angle between the extending direction of the groove and the first edge is C, 5° ≤ C ≤ 85°; the included angle between the extending direction of the groove and the second edge is E, 5° ≤ E ≤ 85°. In the above structure, since the groove in the active material layer communicates with the edge of the first electrode sheet and thus with the cavity, and the range of the included angle C between the extending direction of the groove and the first edge is 5° ≤ C ≤ 85°, and the range of the included angle E between the extending direction of the groove and the second edge is 5° ≤ E ≤ 85°, the groove is inclined relative to two adjacent edges in the first electrode sheet, and the extending direction of the groove has components in the extending direction of the first edge and in the extending direction of the second edge adjacent to the first edge. When the electrolyte flows along the groove, corresponding displacements can be decomposed in the extending direction of the first edge and in the extending direction of the second edge, rather than only having a displacement at a certain edge, so that the drainage of the electrolyte by the groove takes into account the extending directions of two adjacent edges. When the electrolyte in the cavity flows into the electrode assembly from the edge of the outer periphery of the first electrode sheet under the guidance of the groove, the electrolyte can better infiltrate the inside of the electrode assembly, which is beneficial to timely supplement the electrolyte inside the electrode assembly during the cycle process and is beneficial to extending the cycle life of the battery cell.

[0050] The technical solutions of the battery cell and the electrical device using the same provided by the present application will be further described below through specific embodiments.

[0051] Some embodiments of the present application provide a battery cell, as Figure 1 shown. The battery cell includes a housing 1 and an electrode assembly 3. The housing 1 forms a cavity 2 filled with electrolyte, and the electrode assembly 3 is disposed in the cavity 2. Referring to Figure 2 , the electrode assembly 3 includes a plurality of first electrode sheets 31 stacked along the thickness direction X. The first electrode sheet 31 includes a first current collector 311 and an active material layer 312. The first current collector 311 includes two first surfaces 3111 disposed opposite to each other along the thickness direction X. An active material layer 312 is provided on at least one of the first surfaces 3111. Referring to Figure 3, a surface of the active material layer 312 away from the first current collector 311 is recessed inward to form a groove 313, and an end of the groove 313 in the extending direction communicates with an edge of the first pole piece 31; the first pole piece 31 includes a connected first edge and a second edge, and an included angle between the extending direction of the groove and the first edge is C, 5° ≤ C ≤ 85°; an included angle between the extending direction of the groove 313 and the second edge is E, 5° ≤ E ≤ 85°.

[0052] Angle measurement between the groove 313 and the edge: Since the shape of the groove 313 is not necessarily regular during the manufacturing process, the angle measurement method between the groove 313 and the first edge 314 and the second edge 315 is specified here. Please refer to Figure 4 , when both ends of the groove 313 intersect with the edge of the pole piece, an auxiliary line segment is made with two intersection points as endpoints (the intersection points are the intersection points of the edge on the same side in the width direction of the groove 313 and the edge of the pole piece). This line segment is used as the basis for measuring the included angle. When at least one end of the groove 313 does not intersect with the edge of the pole piece, the edge of the pole piece can be translated until it intersects with the groove 313 and then the auxiliary line segment is made.

[0053] The housing 1 can be a wall structure arranged on the periphery in the battery cell, which can form a cavity 2 for accommodating other components of the battery cell such as the electrode assembly 3 and the electrolyte. The housing 1 can protect the components in the cavity 2.

[0054] The electrolyte is a liquid that conducts active ions between the positive electrode plate 33 and the negative electrode plate 34 in the electrode assembly 3. By infiltrating the positive electrode plate 33 and the negative electrode plate 34 in the electrode assembly 3, the active ions can be conducted between the positive electrode plate 33 and the negative electrode plate 34.

[0055] The electrode assembly 3 is an important structure in the battery cell. It is arranged in the cavity 2 and infiltrated by the electrolyte, and can undergo an electrochemical reaction with the electrolyte. The first pole piece 31 is an important component of the electrode assembly 3, and can be the positive electrode plate 33 in the foregoing technical solution, or the negative electrode plate 34 in the foregoing technical solution. Those skilled in the art can set the positive electrode plate 33 or the negative electrode plate 34 as the first pole piece 31 according to the actual situation.

[0056] Reference Figure 2 , a plurality of first pole pieces 31 are stacked along the thickness direction X, so that the electrode assembly 3 has a stacked structure. Exemplarily, a plurality of positive electrode plates 33 and a plurality of negative electrode plates 34 are respectively provided, and the plurality of positive electrode plates 33 and the plurality of negative electrode plates 34 are alternately stacked.

[0057] The first current collector 311 may be the matrix structure in the first electrode tab 31. It can serve as a carrier structure for carrying the active material and can conduct and collect the current generated by the active material. The first current collector 311 may be a metal foil, such as copper foil and aluminum foil, or a composite current collector formed by a polymer material base layer and a metal layer. The first surfaces 3111 may be two surfaces of the first current collector 311 that are relatively spaced apart in the thickness direction X. The first surfaces 3111 can be used to dispose the active material layer 312 so that the active material layer 312 can be carried on the first current collector 311.

[0058] The active material layer 312 may be a layered structure formed by the active material, which is disposed on the first surface 3111 of the first current collector 311. The active material layer 312 is provided on at least one of the first surfaces 3111, which may mean that the active material layer 312 is provided on one of the first surfaces 3111 of the first current collector 311, or may also mean that the active material layer 312 is provided on both of the first surfaces 3111 of the first current collector 311.

[0059] The groove 313 may be a groove-like structure provided on the active material layer 312. By making the surface of the active material layer 312 away from the first current collector 311 recess inward, a groove 313 is formed on the active material layer 312. The end of the groove 313 in the extending direction communicates with the edge of the first electrode tab 31 to communicate with the cavity 2, which may mean that the end of the groove 313 in the extending direction communicates with the edge of the first electrode tab 31. Since the edge of the first electrode tab 31 in the laminated electrode assembly 3 is directly exposed to the cavity 2 and immersed in the electrolyte, the end of the groove 313 communicating with the edge of the first electrode tab 31 communicates with the gap between the electrode assembly 3 and the housing 1, so that the electrolyte in the gap can enter the groove 313 from the end of the groove 313 in the extending direction and flow relatively quickly into the interior of the electrode assembly 3 along the extending direction of the groove 313. The electrolyte in the cavity 2 can timely supplement the interior of the electrode assembly 3, so that the electrolyte can better infiltrate the interior of the electrode assembly 3.

[0060] The first edge 314 and the second edge 315 are two adjacent edges in the first electrode tab 31. The angle C between the extending direction of the groove 313 and the first edge 314 may refer to the smaller of the two angles formed by the extending direction of the groove 313 and the extending direction of the first edge 314. The angle E between the extending direction of the groove 313 and the second edge 315 may refer to the smaller of the two angles formed by the extending direction of the groove 313 and the extending direction of the second edge 315.

[0061] The range of the angle C between the extending direction of the groove 313 and the first edge 314 is set to 5° ≤ C ≤ 85°, and the range of the angle E between the extending direction of the groove 313 and the second edge 315 is set to 5° ≤ E ≤ 85°, so that the groove 313 is neither parallel nor perpendicular to the first edge 314 and the second edge 315.

[0062] By setting the angle between the extending direction of the groove 313 and the first edge 314 as C, and the angle between the extending direction of the groove and the second edge as E, with 5° ≤ E ≤ 85° and 5° ≤ C ≤ 85°, the groove 313 can be inclined relative to two adjacent edges in the first pole piece 31. The extending direction of the groove 313 has components in the extending direction of the first edge 314 and in the extending direction of the second edge 315. When introducing the electrolyte from the edge of the first pole piece 31 into the electrode assembly 3, when the electrolyte flows along the extending direction of the groove 313, corresponding displacements can be decomposed in the extending direction of the adjacent first edge 314 and the extending direction of the second edge 315 of the first pole piece 31. When the electrolyte infiltrates the electrode assembly 3 along the extending direction of the groove 313, compared with the groove design that only follows the length direction or width direction of the first pole piece 31 in the prior art, this solution takes into account the electrolyte flow in two directions, can better infiltrate the inside of the electrode assembly 3, is beneficial to timely supplement the electrolyte inside the electrode assembly during the cycle, and is beneficial to extending the cycle life of the battery cell.

[0063] In some embodiments, the first edge 314 and the second edge 315 form a first corner. The first pole piece 31 includes a diagonal line passing through the first corner. The angle between the diagonal line and the first edge 314 is A, and the angle between the diagonal line and the second edge 315 is B, where A ≥ B; the angle between the extending direction of the groove 313 and the first edge 314 is C, and A + 5° ≤ C ≤ A + 40°.

[0064] The first edge 314 and the second edge 315 form a first corner at the connection. The angle between the diagonal line at the first corner and the first edge 314 is A, and the angle between the diagonal line at the first corner and the second edge 315 is B, where A ≥ B, such that A is the larger angle formed by the diagonal line at the first corner and the edge of the first pole piece 31.

[0065] The electrolyte that infiltrates into the interior of the electrode assembly 3 along the groove 313 introduced from the first edge 314 and the second edge 315 can reach the interior region of the electrode assembly 3 at a closer time, enabling the groove 313 to more uniformly supply the electrolyte from the cavity 2 surrounding the electrode assembly 3 to the interior of the electrode assembly 3, so that the groove 313 can not only improve the wettability of the electrolyte to the electrode assembly 3, but also improve the uniformity of the utilization of the electrolyte.

[0066] In some embodiments, A + 15° ≤ C ≤ A + 35°.

[0067] By setting the range of the angle C between the extending direction of the groove 313 and the first edge 314 to A + 15° ≤ C ≤ A + 35°, the electrolyte that infiltrates into the interior of the electrode assembly 3 along the groove 313 introduced from the first edge 314 and the second edge 315 can reach the interior region of the electrode assembly 3 at a closer time, enabling the groove 313 to more uniformly supply the electrolyte from the cavity 2 surrounding the electrode assembly 3 to the interior of the electrode assembly 3, so that the groove 313 can not only improve the wettability of the electrolyte to the electrode assembly 3, but also improve the uniformity of the utilization of the electrolyte.

[0068] Exemplarily, the angle C between the extending direction of the groove 313 and the first edge 314 can be set to A + 15°, A + 25°, or A + 35°, so that the electrolyte that infiltrates into the interior of the electrode assembly 3 along the groove 313 introduced from the first edge 314 and the second edge 315 can reach the interior region of the electrode assembly 3 at a closer time and at the same time can more uniformly supply the electrolyte from the cavity 2 surrounding the electrode assembly 3 to the interior of the electrode assembly 3, so that the groove 313 can not only improve the wettability of the electrolyte to the electrode assembly 3, but also improve the uniformity of the utilization of the electrolyte.

[0069] Exemplarily, when the first pole piece 31 includes a plurality of rectangular parts, the first pole piece 31 is divided into a plurality of separate rectangular parts, and diagonals are respectively set in the plurality of separate rectangular parts, and the diagonal is used as the diagonal of the first pole piece 31.

[0070] In some embodiments, the first pole piece 31 includes a first part and a second part that are connected to each other. The first part and the second part are both configured as rectangles, and the first corner is located in the first part or the second part; in the first part and the second part, the average angle of the angles between all the diagonals and the first edge is V, and V + 15° ≤ C ≤ V + 35°.

[0071] The first part and the second part are two interconnected parts in the first pole piece 31 respectively. The first part and the second part can be interconnected according to actual conditions to form the first pole piece 31 with a specific shape required for the electrode assembly 3. Exemplarily, the first part and the second part can be an integrally formed structure, and the first part and the second part can be synchronously made by a die-cutting process.

[0072] Reference Figure 5 and Figure 6 , by configuring both the first part and the second part as rectangles, the first part and the second part can form an L-shaped pole piece or a T-shaped pole piece. The first edge 314 and the second edge 315 form the first corner located on the first part, which can mean that the first edge 314 and the second edge 315 are two adjacent edges of the first part, and a first corner is formed between the first edge 314 and the second edge 315. The first edge 314 and the second edge 315 form the first corner located on the second part, which can mean that the first edge 314 and the second edge 315 are two adjacent edges of the second part, and a first corner is formed between the first edge 314 and the second edge 315.

[0073] When the first pole piece 31 includes two parts, namely a first part and a second part which are both rectangular, when setting the first corner and the diagonal on the first pole piece 31, it is necessary to divide the first pole piece 31 into two parts, namely the first part and the second part, and set the first corner and the diagonal separately. That is to say, the diagonal is the diagonal in the rectangular first part or the rectangular second part.

[0074] In the first part and the second part, the average angle between all the diagonals and the first edge 314 is V, which can mean that V is the average angle between all the diagonals and the first edge 314 in the first part and the second part. By setting the range of V as V + 15° ≤ C ≤ V + 35°, when the first pole piece 31 is an L-shaped pole piece or a T-shaped pole piece formed by two parts, the angle between the extending direction of the groove 313 on the first pole piece 31 and the first edge 314 of any first corner can be within a reasonable range, so that the groove 313 has components on both edges of the first corner, and the groove 313 can well infiltrate the interior of the L-shaped pole piece or the T-shaped pole piece formed by two parts.

[0075] In some embodiments, reference Figure 7 , the groove 313 extends along the first direction Y, and the first direction Y is perpendicular to the thickness direction X; along the first direction Y, the length of the groove 313 is L, and the length of the first pole piece 31 is N,

[0076] The first direction Y can be a direction perpendicular to the thickness direction X of the first current collector 311. By extending the groove 313 along the first direction Y, the groove 313 can be arranged in a plane direction perpendicular to the thickness direction X.

[0077] The length N of the first pole piece 31 along the first direction Y can refer to the length of the line connecting the intersections of the extension line of the groove 313 extending along the first direction Y and the two edges of the first pole piece 31. By setting the length of the groove 313 along the first direction Y to L, setting the length of the first pole piece 31 along the first direction Y to N, and setting the relationship between the length L of the groove 313 along the first direction Y and the length N of the first pole piece 31 along the first direction Y as such that the length of the groove 313 along the first direction Y is greater than or equal to half of the length of the first pole piece 31 along the first direction Y, so that the groove 313 can at least guide the electrolyte to the central position of the first pole piece 31 in the first direction Y, enabling the central position of the first pole piece 31 to be replenished with electrolyte in a timely manner.

[0078] In some embodiments, referring to Figures 4 to 6 , the groove 313 penetrates the active material layer 312 along the first direction Y.

[0079] The groove 313 penetrating the active material layer 312 along the first direction Y can mean that the groove 313 extending along the first direction Y penetrates the active material layer 312, such that the groove 313 has two ends communicating with the edges of the first pole piece 31, enabling the electrolyte in the cavity 2 to enter the groove 313 from the two ends in the extending direction of the groove 313, allowing more electrolyte to flow into the groove 313, which is beneficial to reducing the occurrence of the lack of electrolyte inside the electrode assembly 3.

[0080] In some embodiments, referring to Figure 8 , there are multiple grooves 313, and at least two grooves 313 intersect.

[0081] The intersection setting of at least two grooves 313 can mean that at least two of the multiple grooves 313 are connected, enabling at least two grooves 313 to guide the electrolyte to the preset area simultaneously, which is beneficial to improving the speed of replenishing the electrolyte in the preset area.

[0082] Exemplarily, in the electrode assembly 3 in a stacked structure, the multiple grooves 313 can be arranged radially, as shown in Figure 8 , and the multiple grooves 313 arranged radially from the center to the outside guide the electrolyte into the electrode assembly 3.

[0083] In some embodiments, there are multiple grooves 313, the multiple grooves 313 are arranged at intervals, and the extending directions of at least two grooves 313 intersect.

[0084] As described in the foregoing technical solution, the multiple grooves 313 formed on the active material layer 312 can better guide the electrolyte into the electrode assembly 3, so that the electrolyte inside the electrode assembly 3 can be replenished more in time.

[0085] The intersecting arrangement of the extending directions of at least two grooves 313 may mean that the extending directions of at least two grooves 313 are not parallel, so that the multiple grooves 313 can be adaptively arranged according to the demand degree of the electrolyte inside the electrode assembly 3.

[0086] In some embodiments, the groove 313 includes a first groove 3131 and the second groove 3132. The first groove 3131 extends along a first direction Y, and there are multiple first grooves 3131. The multiple first grooves 3131 are arranged at intervals along a second direction Z. The second direction Z, the thickness direction X, and the first direction Y are perpendicular to each other; the extending direction of the second groove 3132 intersects with the extending direction of the first groove 3131.

[0087] The first groove 3131 extending along the first direction Y may mean that the extending direction of the first groove 3131 is along the first direction Y. By making all the first grooves 3131 extend along the first direction Y, the groove 313 can guide the electrolyte along the first direction Y and can timely replenish the electrolyte to a specific area inside the electrode assembly 3, especially the area where the electrolyte is prone to shortage.

[0088] The second direction Z may be a direction perpendicular to both the first direction Y and the thickness direction X. By arranging the multiple first grooves 3131 at intervals along the second direction Z, the multiple first grooves 3131 can be conveniently arranged in parallel on the surface perpendicular to the thickness direction X and can replenish the electrolyte to a specific area in large quantities and in time along the second direction Z.

[0089] Exemplarily, the interval arrangement of the multiple first grooves 3131 along the second direction Z can be an equal interval arrangement, so that the guiding effect of each part of the first pole piece 31 on the electrolyte is the same, or it can be an unequal interval arrangement. The distance between two adjacent grooves 313 is set smaller in the area where the electrolyte demand is large, and the distance between two adjacent grooves 313 is set larger in the area where the electrolyte demand is small, so as to meet the electrolyte demand conditions in different areas of the electrode assembly 3.

[0090] The second groove 3132 is a groove whose extending direction intersects with the extending direction of the first groove 3131. By arranging the extending direction of the second groove 3132 to intersect with the extending direction of the first groove 3131, a plurality of grooves 313 can be adaptively arranged according to the demand degree of the electrolyte inside the electrode assembly 3.

[0091] In some embodiments, referring to Figure 9 , a plurality of first grooves 3131 are arranged at equal intervals along the second direction Z. The interval between two adjacent first grooves 3131 in the second direction Z is H, and 100 μm ≤ H ≤ 5000 μm.

[0092] The arrangement of a plurality of first grooves 3131 at equal intervals along the second direction Z does not mean that all intervals H are strictly equal in a strict sense. There may be process errors, and the error range is ±5 μm. By arranging a plurality of first grooves 3131 at equal intervals along the second direction Z, the plurality of first grooves 3131 are evenly distributed on the active material layer 312, so that the improvement of the wettability of the first grooves 3131 on the electrode assembly 3 is uniform, and the electrolyte inside the electrode assembly 3 can be supplemented more evenly.

[0093] By setting the range of the interval H between two adjacent first grooves 3131 in the second direction Z to 100 μm ≤ H ≤ 5000 μm, not only do a plurality of first grooves 3131 have sufficient density to guide the electrolyte into the electrode assembly 3, so that the inside of the electrode assembly 3 is well wetted, but also the first grooves 3131 on the active material layer 312 are not easily reduced in structural strength due to excessive density.

[0094] In some embodiments, 400 μm ≤ H ≤ 2500 μm.

[0095] By setting the range of the interval H between two adjacent first grooves 3131 in the second direction Z to 400 μm ≤ H ≤ 2500 μm, not only do a plurality of first grooves 3131 have sufficient density to guide the electrolyte into the electrode assembly 3, so that the inside of the electrode assembly 3 is well wetted, but also the first grooves 3131 on the active material layer 312 are not easily reduced in structural strength due to excessive density.

[0096] Preferably, the range of the interval H between two adjacent first grooves 3131 in the second direction Z is set to 500 μm ≤ H ≤ 2000 μm. Exemplarily, the interval between two adjacent first grooves 3131 in the second direction Z can be set to 500 μm, 1000 μm, 1500 μm or 2000 μm, so that a plurality of first grooves 3131 have sufficient density to guide the electrolyte into the electrode assembly 3, and while the inside of the electrode assembly 3 is well wetted, the active material layer 312 also has sufficient structural strength.

[0097] In some embodiments, the width of the opening of the first groove 3131 in the second direction Z is J, and 40 μm ≤ J ≤ 250 μm.

[0098] By setting the width of the opening of the first groove 3131 in the second direction Z to J and setting the range of this width J to 40 μm ≤ J ≤ 250 μm, not only does the first groove 3131 have a sufficient width in the second direction Z to have a sufficient cross-sectional area, but also the first groove 3131 is not likely to affect the structural strength of the active material layer 312 due to an overly large opening.

[0099] In some embodiments, 50 μm ≤ J ≤ 200 μm.

[0100] By setting the range of the width J of the opening of the first groove 3131 in the second direction Z to 50 μm ≤ J ≤ 200 μm, not only does the first groove 3131 have a sufficient width in the second direction Z to have a sufficient cross-sectional area, but also the first groove 3131 is not likely to affect the structural strength of the active material layer 312 due to an overly large opening.

[0101] Preferably, the range of the width J of the opening of the first groove 3131 in the second direction Z is set to 60 μm ≤ J ≤ 150 μm. Exemplarily, the spacing between two adjacent first grooves 3131 in the second direction Z can be set to 60 μm, 90 μm, 120 μm, or 150 μm, so that the first groove 3131 has a sufficient cross-sectional area while also enabling the active material layer 312 to have sufficient structural strength.

[0102] In some embodiments, along the thickness direction X, the depth of the groove 313 is K, and the thickness of the active material layer 312 is M.

[0103] The depth of the groove 313 along the thickness direction X may refer to the depth of the groove 313, and the thickness of the active material layer 312 along the thickness direction X may refer to the thickness of the active material layer 312. By setting the relationship between the depth K of the groove 313 and the thickness M of the active material layer 312 to the groove 313 is not likely to affect the structural strength of the active material layer 312 due to an overly deep depth.

[0104] In some embodiments, along the thickness direction X, the depth of the groove 313 is K, and 4 μm ≤ K ≤ 45 μm.

[0105] By setting the depth of the groove 313 in the thickness direction X to K and setting the range of K to 4 μm ≤ K ≤ 45 μm, not only does the groove 313 have sufficient depth to guide the electrolyte to flow into the electrode assembly 3, but also the depth of the groove 313 is not likely to damage the structure of the active material layer 312 due to excessive depth, resulting in too low structural strength of the active material layer 312.

[0106] In some embodiments, 5 μm ≤ K ≤ 40 μm.

[0107] By setting the range of the dimension K of the groove 313 in the thickness direction X to 5 μm ≤ K ≤ 40 μm, not only does the groove 313 have sufficient depth to guide the electrolyte to flow into the electrode assembly 3, but also the depth of the groove 313 is not likely to damage the structure of the active material layer 312 due to excessive depth, resulting in too low structural strength of the active material layer 312. Preferably, the range of the dimension K of the groove 313 in the thickness direction X can be set to 8 μm ≤ K ≤ 25 μm. Exemplarily, the dimension of the groove 313 in the thickness direction X can be set to 8 μm, 12 μm, 16 μm, 20 μm or 25 μm, so that while the groove 313 has sufficient depth to guide the electrolyte to flow into the electrode assembly 3, the depth of the groove 313 is not likely to damage the structural strength of the active material layer 312 due to excessive depth.

[0108] In some embodiments, the groove 313 is formed by laser grooving or chemical etching.

[0109] The groove 313 is formed by laser grooving, which may mean that the groove 313 is formed by processing with a laser on the surface of the active material layer 312 away from the first current collector 311. The groove 313 is formed by chemical etching, which may mean that the groove 313 is formed by corroding the surface of the active material layer 312 away from the first current collector 311 with a chemical reagent.

[0110] In some embodiments, the cross-sectional shape of the groove 313 is one of a triangle, a trapezoid, a semi-circle, and a rectangle.

[0111] The cross-section of the groove 313 may refer to a cross-section perpendicular to the extending direction of the groove 313. The cross-sectional shape of the groove 313 being one of a triangle, a trapezoid, a semi-circle, and a rectangle may mean that the cross-sectional shape of each of the plurality of grooves 313 is a triangle, a trapezoid, a semi-circle or a rectangle; or it may mean that the cross-sectional shapes of the grooves 313 among the plurality of grooves 313 are various, and each of the plurality of grooves 313 can be one of a triangle, a trapezoid, a semi-circle, and a rectangle. Those skilled in the art can select the cross-sectional shape of the groove 313 according to the actual situation.

[0112] In some embodiments, the first pole piece 31 is the negative pole piece 34.

[0113] By setting the first pole piece 31 as the negative pole piece 34, such that the groove 313 is provided on the active material layer 312 of the negative pole piece 34, not only can the electrolyte infiltrate into the interior of the electrode assembly 3 along the negative pole piece 34, but also the active ion embedding sites on the negative pole piece 34 can be increased, which is beneficial to the diffusion of active ions and helps to reduce the problem of ion precipitation.

[0114] The beneficial effects of the battery cells provided by the specific embodiments of the present application are further described below through comparative experiments.

[0115] A fiber laser is used to form a plurality of parallel and equally spaced grooves 313 in the active material layer of the negative pole piece. The depth K of the formed groove 313 is 12 μm, the width J of the opening of the groove 313 is 90 μm, and the interval H between two adjacent grooves 313 is 1300 μm. After laminating the negative pole piece and the positive pole piece to form an electrode assembly, it is installed in the housing 1 made of aluminum-plastic material, electrolyte is injected, and after processes such as encapsulation and formation, the battery cells provided by the embodiments of the present application are manufactured.

[0116] The battery cells without the grooves 313 manufactured by the same process method are used as the battery cells for the comparative example.

[0117] The differences between the negative pole pieces in each comparative example and embodiment are as follows:

[0118] Table 1

[0119]

[0120] The cycle performance and cycle interface of the battery cells in the above comparative examples and embodiments are evaluated. The specific method is as follows:

[0121] The cycle performance of the battery cells is evaluated by the capacity retention rate. The calculation method of the capacity retention rate is to charge and discharge the battery cells in the comparative examples and embodiments 500 times using the same charging process at an ambient temperature of 25°C, and then divide the discharge capacity of the battery cells after 500 cycles of charge and discharge by the discharge capacity at the first time to obtain the capacity retention rate.

[0122] The charging process of the battery cells is as follows:

[0123] Step 1: Charge the battery cell at a constant current of 2C to 4.5V;

[0124] Step 2: Charge the battery cell at a constant voltage of 4.5V to 0.05C;

[0125] Step 3: Let the battery cell stand for 5 minutes;

[0126] Step 4: Discharge the battery cell at a constant current of 0.5C to 3.0V;

[0127] Step 5: Let the battery cell stand still for 5 minutes;

[0128] Step 6: Repeat the above Steps 1 to 5 for 500 times.

[0129] The evaluation of the cycling interface of the battery cell is carried out by observing the lithium deposition situation on the negative electrode plate. The battery cell that has undergone 500 charge-discharge cycles is disassembled, and the interface of the negative electrode plate is observed and compared. In order to describe the lithium deposition situation on the cycling interface, the interface situation is now classified. Through the naked eye observation of the operator, if the surface of the negative electrode plate is golden yellow and there is no abnormal phenomenon, it is determined that there is no lithium deposition; if there are intermittent dot-like purple spots, lithium deposition or lithium deposition on the purple spots on the negative electrode plate, it is determined that there is slight lithium deposition; if there are large-area continuous purple spots, lithium deposition or lithium deposition on the purple spots on the main body of the negative electrode plate, and the abnormal area ratio is less than 50%, it is determined that there is lithium deposition; if there are large-area continuous purple spots, lithium deposition or lithium deposition on the purple spots on the main body of the negative electrode plate, and the abnormal area ratio is greater than or equal to 50%, it is determined that there is serious lithium deposition.

[0130] The cycling performance and cycling interface of the battery cells in the comparative examples and examples are as follows:

[0131] Table 2

[0132]

[0133] As can be seen from Table 1 and Table 2, when the electrode compaction is relatively high, the wettability of the unslotted electrode assemblies in Comparative Examples 1-3 is poor, and serious lithium deposition occurs in the later stage of cycling, and at the same time, the capacity retention rate is significantly reduced; by comparing Example 1 with Comparative Example 1, it can be seen that after forming the groove 313 on the negative electrode plate, the wettability of the electrode assembly is improved, and both the capacity retention rate and the cycling interface are significantly improved, but the angle C between the extending direction of the groove 313 and the first edge 314 is not within the optimal angle range. Taking Examples 4-10 as an example, it can be seen that when C is between (A + 15°) and

[0134] (A + 40°), the capacity retention rate is better, and when C is between (A + 15°) and (A + 35°), the capacity retention rate is further improved.

[0135] Some embodiments of the present application further provide an electrical device, and this electrical device includes the battery cell provided by the above technical solution, and the battery cell is used to provide electrical energy. Since this electrical device includes the battery cell provided by the above technical solution, this electrical device has a long service life.

[0136] Although the present application has been described with reference to preferred embodiments, various modifications can be made thereto without departing from the scope of the present application, and components thereof can be replaced with equivalents. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any manner. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: A shell, forming a cavity, wherein the cavity is filled with an electrolyte; An electrode assembly is arranged in the cavity, and the electrode assembly includes a plurality of first pole pieces stacked along the thickness direction, the first pole piece includes a first current collector and an active material layer, the first current collector includes two first surfaces arranged opposite to each other along the thickness direction, at least one of the first surfaces is provided with the active material layer, the surface of the active material layer away from the first current collector is recessed inward to form a groove, and the end of the groove in the extension direction is connected to the edge of the first pole piece; the first pole piece includes a first edge and a second edge connected, the angle between the extension direction of the groove and the first edge is C, 5°≤C≤85°; the angle between the extension direction of the groove and the second edge is E, 5°≤E≤85°.

2. The battery cell according to claim 1, characterized in that: The first edge and the second edge form a first corner, the first pole piece includes a diagonal line passing through the first corner, the angle between the diagonal line and the first edge is A, and the angle between the diagonal line and the second edge is B, wherein A≥B; the angle between the extension direction of the groove and the first edge is C, and A+5°≤C≤A+40°.

3. The battery cell according to claim 2, characterized in that: A+15°≤C≤A+35°.

4. The battery cell according to claim 2, characterized in that: The first pole piece includes a first part and a second part which are connected to each other, the first part and the second part are both configured as a rectangle, and the first corner is located in the first part or the second part; in the first part and the second part, the average angle of all the diagonals and the first edge is V, V+15°≤C≤V+35°.

5. The battery cell according to claim 1, characterized in that: The groove extends along a first direction, and the first direction is perpendicular to the thickness direction; along the first direction, the length of the groove is L, and the length of the first pole piece is N, 6. The battery cell according to claim 5, characterized in that: The groove penetrates the active material layer along a first direction.

7. The battery cell according to claim 1, characterized in that: There are a plurality of grooves, the grooves are arranged at intervals, and the extension directions of at least two of the grooves intersect.

8. The battery cell according to claim 7, characterized in that: The grooves include a plurality of first grooves and a plurality of second grooves, the first grooves extend along a first direction, the plurality of first grooves are spaced apart along a second direction, the second direction, the thickness direction and the first direction are perpendicular to each other; the extension direction of at least one of the second grooves intersects with the extension direction of the first groove.

9. The battery cell according to claim 8, characterized in that: The interval between two adjacent first grooves in the second direction is H, and 100 μm≤H≤5000 μm.

10. The battery cell according to claim 9, characterized in that: 400μm≤H≤2500μm.

11. The battery cell according to claim 8, characterized in that: The width of the opening of the first groove in the second direction is J, and 40 μm≤J≤250 μm.

12. The battery cell according to claim 11, characterized in that: 50μm≤J≤200μm.

13. The battery cell according to claim 1, characterized in that: Along the thickness direction, the depth of the groove is K, the thickness of the active material layer is M, 14. The battery cell according to claim 1, characterized in that: Along the thickness direction, the depth of the groove is K, 4 μm≤K≤45 μm.

15. The battery cell according to claim 14, characterized in that: 5μm≤K≤40μm.

16. The battery cell according to claim 1, characterized in that: The groove is formed by laser engraving or chemical etching.

17. The battery cell according to claim 1, characterized in that: The cross-sectional shape of the groove is one of a triangle, a trapezoid, a semicircle, and a rectangle.

18. The battery cell according to claim 1, characterized in that: The first pole piece is a negative pole piece.

19. An electrical device, characterized in that: The invention comprises a battery cell as described in any one of claims 1 to 18, wherein the battery cell is used to provide electrical energy.

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