Pole piece, battery cell and electronic equipment

Abstract

The utility model relates to the technical field of batteries, in particular to a pole piece, a battery cell and electronic equipment. The pole piece comprises a current collector, a first active substance layer and a first coating layer, the current collector is provided with a first surface, the first active substance layer is arranged on the first surface, and a plurality of first grooves are formed in the side, away from the current collector, of the first active substance layer at intervals; the first coating layer is arranged on one side, far away from the current collector, of the first active material layer, and the first coating layer is embedded into the first groove. The battery cell comprises the pole piece. The electronic equipment comprises the battery cell. According to the utility model, the fast charging rate of the pole piece, the battery cell and the electronic equipment can be improved, and the use safety of the pole piece, the battery cell and the electronic equipment can be ensured.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to an electrode, a battery cell, and an electronic device. Background Technology

[0002] With the continuous development of technology, lithium-ion batteries are being used more and more widely. In lithium-ion batteries, the electrode is the core component. The battery includes a positive electrode and a negative electrode. The positive electrode is coated with a positive active material coating, and the negative electrode is coated with a negative active material coating. Lithium ions in the battery can continuously migrate between the positive and negative active material coatings, thereby realizing the charging and discharging of the battery.

[0003] To improve the fast-charging capability of batteries, a technique of drilling holes in the active material coating of the electrodes can be used. This allows lithium ions to more easily embed into the active material coating at the drilling points, thereby improving the battery's dynamic performance. However, the active material coating particles at the drilling points are prone to detachment. These detached particles can easily puncture the separator in the battery, causing self-discharge and resulting in an internal short circuit. Utility Model Content

[0004] The main purpose of this invention is to propose an electrode, a battery cell, and an electronic device, which aims to solve the technical problem that the active material coating particles at the perforation location on the electrode are easy to fall off, thereby easily causing the battery to self-discharge and internal short circuit.

[0005] To achieve the above objectives, this utility model proposes an electrode sheet, comprising:

[0006] A current collector having a first surface;

[0007] A first active material layer is disposed on the first surface, and a plurality of first grooves are provided at intervals on the side of the first active material layer away from the current collector.

[0008] A first coating layer is disposed on the side of the first active material layer away from the current collector, and the first coating layer is embedded in the first groove.

[0009] In some embodiments, the current collector has a second surface disposed opposite to the first surface, the second surface is provided with a second active material layer, the second active material layer is provided with a plurality of second grooves at intervals on the side away from the current collector, the second active material layer is provided with a second coating layer on the side away from the current collector, and the second coating layer is embedded in the second grooves.

[0010] In some embodiments, the first coating layer has a first recess on the side away from the first active substance layer, and the second coating layer has a second recess on the side away from the second active substance layer.

[0011] In some embodiments, the size of the first coating layer is not less than the size of the first active material layer, and the size of the first coating layer is not greater than the size of the current collector;

[0012] The size of the second coating layer is not less than the size of the second active material layer, and the size of the second coating layer is not greater than the size of the current collector.

[0013] In some embodiments, the total groove volume V1 of the first groove on the first active material layer and the volume V2 of the first active material layer satisfy the following: 0.3% ≤ V1 / V2 ≤ 1%; the groove depth H1 of the first groove and the thickness H2 of the first active material layer satisfy the following: 10% ≤ H1 / H2 ≤ 50%.

[0014] The total groove volume V3 on the second active material layer and the volume V4 of the second active material layer satisfy the following: 0.3% ≤ V3 / V4 ≤ 1%; the groove depth H3 of the second groove and the thickness H4 of the second active material layer satisfy the following: 10% ≤ H3 / H4 ≤ 50%.

[0015] In some embodiments, along the length direction of the electrode sheet, the groove width L1 of the first groove and the spacing distance L2 between two adjacent first grooves satisfy: 1% ≤ L1 / L2 ≤ 5%.

[0016] Along the length of the electrode, the groove width L3 of the second groove and the spacing L4 between two adjacent second grooves satisfy the following condition: 1% ≤ L3 / L4 ≤ 5%.

[0017] In some embodiments, the thickness H5 of the first coating layer and the thickness H2 of the first active material layer satisfy the following: 1% ≤ H5 / H2 ≤ 10%;

[0018] The thickness H6 of the second coating layer and the thickness H4 of the second active material layer satisfy the following condition: 1% ≤ H6 / H4 ≤ 10%.

[0019] In some embodiments, the first coating layer is a composite structure composed of one of polyamide fiber, polyvinylidene fluoride, polymethyl methacrylate, polyacrylate, and one of alumina, boehmite, magnesium oxide, magnesium hydroxide, silicon oxide, solid electrolyte, and lithium supplement.

[0020] The second coating layer is a composite structure composed of one of polyamide fiber, polyvinylidene fluoride, polymethyl methacrylate, polyacrylate, and one of alumina, boehmite, magnesium oxide, magnesium hydroxide, silicon oxide, solid electrolyte, and lithium supplement.

[0021] Correspondingly, this utility model also proposes a battery cell, comprising:

[0022] At least two electrodes as described in the above embodiments, wherein the two electrodes are stacked together;

[0023] A diaphragm is disposed between the two electrodes;

[0024] The encapsulation housing has a receiving cavity, and the electrode and the diaphragm are disposed within the receiving cavity.

[0025] Correspondingly, this utility model also proposes an electronic device, including the battery cell described in the above embodiments.

[0026] Compared with the prior art, the beneficial effects of this utility model are:

[0027] In the technical solution of this utility model, after the first active material layer is coated on the first surface of the current collector, the first active material layer needs to be rolled to ensure that the first active material layer can be tightly bonded to the current collector. After the first active material layer is rolled, the side of the first active material layer away from the current collector is in direct contact with the pressure roller, making it easier to compact. This results in a smaller porosity on the side of the first active material layer away from the current collector and a larger porosity on the side closer to the current collector. Since a larger porosity makes it easier for lithium ions to embed into the first active material layer, and a smaller porosity makes it harder for lithium ions to embed, several first grooves are spaced apart on the side of the first active material layer away from the current collector (where the porosity is smaller). The porosity at the first grooves is greater than the porosity of the un-perforated areas on the surface of the first active material layer. Lithium ions can easily embed into the interior of the first active material layer from the first grooves, or easily detach from the first active material layer from the first grooves, thereby improving the charging rate and fast-charging performance of the electrode.

[0028] Furthermore, in this invention, since active material particles are prone to detachment at the first groove, a first coating layer is provided on the side of the first active material layer away from the current collector, and the first coating layer is embedded in the first groove. The first coating layer can cover the first active material layer and the first groove, so that all the active material particles on the electrode are covered in the first coating layer, ensuring that the active material particles cannot detach to the outside of the first coating layer, thereby ensuring that the active material particles will not damage the internal structure of the battery and improving the safety of battery use.

[0029] The battery cells and electronic devices using the aforementioned electrodes can ensure both improved fast charging speeds and safe operation. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0031] Figure 1 This is a front view of the structure of an electrode sheet provided in an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the structural parameters of an electrode sheet provided in an embodiment of the present invention;

[0033] Figure 3 This is a top view of the structure of an electrode sheet provided in an embodiment of the present invention;

[0034] Figure 4 This is a bottom view of the structure of an electrode sheet provided in an embodiment of the present invention.

[0035] Explanation of icon numbers:

[0036] 100-current collector;

[0037] 110 - First surface; 120 - Second surface;

[0038] 200 - First active substance layer;

[0039] 210 - First groove;

[0040] 300 - First coating layer;

[0041] 310 - First recessed portion;

[0042] 400 - Second active material layer;

[0043] 410 - Second groove;

[0044] 500 - Second coating layer;

[0045] 510 - Second recess.

[0046] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0047] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0048] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0049] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or," "and / or," or "and / or" throughout the text implies three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where A and B are simultaneously satisfied. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0050] With the continuous development of technology, lithium-ion batteries are being used more and more widely. In lithium-ion batteries, the electrode is the core component. The battery includes a positive electrode and a negative electrode. The positive electrode is coated with a positive active material coating, and the negative electrode is coated with a negative active material coating. Lithium ions in the battery can continuously migrate between the positive and negative active material coatings, thereby realizing the charging and discharging of the battery.

[0051] To improve the fast-charging capability of batteries, a technique of drilling holes in the active material coating of the electrodes can be used. This allows lithium ions to more easily embed into the active material coating at the drilling points, thereby improving the battery's dynamic performance. However, the active material coating particles at the drilling points are prone to detachment. These detached particles can easily puncture the separator in the battery, causing self-discharge and resulting in an internal short circuit.

[0052] Based on this, in order to solve the technical problem that the active material coating particles at the perforation sites on the electrode are prone to detachment, thereby easily leading to self-discharge and internal short circuits in the battery, refer to Figures 1 to 4 An embodiment of the present invention provides an electrode sheet, which includes a current collector 100, a first active material layer 200 and a first coating layer 300. The current collector 100 has a first surface 110, the first active material layer 200 is disposed on the first surface 110, and a plurality of first grooves 210 are provided at intervals on the side of the first active material layer 200 away from the current collector 100. The first coating layer 300 is disposed on the side of the first active material layer 200 away from the current collector 100 and is embedded in the first grooves 210.

[0053] Specifically, in this embodiment, after the first active material layer 200 is coated on the first surface 110 of the current collector 100, the first active material layer 200 needs to be rolled to ensure that it is tightly bonded to the current collector 100. After rolling, the side of the first active material layer 200 away from the current collector 100 is in direct contact with the roller, making it easier to compact. This results in a lower porosity on the side of the first active material layer 200 away from the current collector 100, while the porosity on the side closer to the current collector 100 is higher. Higher porosity makes it easier for lithium ions to embed into the first active material layer 200, while lower porosity makes it more difficult for lithium ions to embed into the first active material layer 200. In order to improve the lithium intercalation capability of the electrode, a number of first grooves 210 are provided at intervals on the side of the first active material layer 200 away from the current collector 100 (the porosity of this side is small). The porosity of the first grooves 210 is greater than the porosity of the unperforated part of the surface of the first active material layer 200. Lithium ions can easily be inserted into the interior of the first active material layer 200 from the first grooves 210, or lithium ions can easily be extracted from the interior of the first active material layer 200 from the first grooves 210, which is beneficial to improving the charging rate of the electrode and enhancing the fast charging performance of the electrode.

[0054] Furthermore, in this embodiment, since active material particles are prone to detachment at the first groove 210, a first coating layer 300 is provided on the side of the first active material layer 200 away from the current collector 100, and the first coating layer 300 is embedded in the first groove 210. The first coating layer 300 can cover the first active material layer 200 and the first groove 210, so that all the active material particles on the electrode are covered in the first coating layer 300, ensuring that the active material particles cannot detach to the outside of the first coating layer 300, thereby ensuring that the active material particles will not damage the internal structure of the battery and improving the safety of battery use.

[0055] Furthermore, in some embodiments, the first groove 210 can be formed by laser drilling, or by mechanical removal.

[0056] Furthermore, in some embodiments, reference is made to Figure 3 Along the width direction of the electrode, the first groove 210 can extend in a straight line from one end of the electrode to the opposite end of the electrode. Alternatively, along the width direction of the electrode, the first groove 210 can extend in a discontinuous manner from one end of the electrode to the opposite end of the electrode.

[0057] It should be noted that in this embodiment, the current collector 100 can be a positive current collector or a negative current collector. When the current collector 100 is a positive current collector, it can be made of materials such as aluminum foil, and the first active material layer 200 is a positive active material layer, which can be made of ternary materials or lithium-rich materials, etc. When the current collector 100 is a negative current collector, it can be made of materials such as copper foil, and the first active material layer 200 is a negative active material layer, which can be made of graphite materials or silicon-based materials, etc.

[0058] In some embodiments, refer to Figure 1 and Figure 2 The current collector 100 has a second surface 120 disposed opposite to the first surface 110. A second active material layer 400 is disposed on the second surface 120. A plurality of second grooves 410 are spaced apart on the side of the second active material layer 400 away from the current collector 100. A second coating layer 500 is disposed on the side of the second active material layer 400 away from the current collector 100, and the second coating layer 500 is embedded within the second grooves 410. For example, the second active material layer 400 and the first active material layer 200 may have the same polarity; both the second active material layer 400 and the first active material layer 200 may be positive electrode active material layers, or both may be negative electrode active material layers.

[0059] Specifically, referring to the above embodiment, for the same reasons as the first active material layer 200, the porosity of the side of the second active material layer 400 away from the current collector 100 is relatively small, while the porosity of the side of the second active material layer 400 close to the current collector 100 is relatively large. Since the larger the porosity, the easier it is for lithium ions to embed into the second active material layer 400; and the smaller the porosity, the less easy it is for lithium ions to embed into the second active material layer 400, in order to improve the lithium embedding capability of the electrode, a plurality of second grooves 410 are provided at intervals on the side of the second active material layer 400 away from the current collector 100 (the porosity of this side is small). The porosity at the second grooves 410 is greater than the porosity of the unperforated part of the surface of the second active material layer 400. Lithium ions can easily embed into the interior of the second active material layer 400 from the second grooves 410, or lithium ions can easily escape from the interior of the second active material layer 400 from the second grooves 410, thereby improving the charging rate of the electrode and enhancing the fast charging performance of the electrode.

[0060] Furthermore, in some embodiments, reference is made to Figure 4 Along the width direction of the electrode, the second groove 410 can extend in a straight line from one end of the electrode to the opposite end of the electrode. Alternatively, along the width direction of the electrode, the second groove 410 can extend in a discontinuous manner from one end of the electrode to the opposite end of the electrode.

[0061] In some embodiments, refer to Figure 1 and Figure 2 The first coating layer 300 has a first recess 310 on the side away from the first active substance layer 200, and the second coating layer 500 has a second recess 510 on the side away from the second active substance layer 400.

[0062] Specifically, in this embodiment, when the first coating layer 300 is embedded in the first groove 210, the side of the first coating layer 300 away from the first groove 210 will naturally depression, forming a first recessed portion 310. Similarly, when the second coating layer 500 is embedded in the second groove 410, the side of the second coating layer 500 away from the second groove 410 will naturally depression, forming a second recessed portion 510.

[0063] Alternatively, in some embodiments, the first recess 310 may be manually provided on the side of the first coating layer 300 away from the first groove 210. Similarly, the second recess 510 may be manually provided on the side of the second coating layer 500 away from the second groove 410.

[0064] A first recess 310 is provided on the side of the first coating layer 300 away from the first active material layer 200, and a second recess 510 is provided on the side of the second coating layer 500 away from the second active material layer 400. When the electrode is subsequently encapsulated to form a battery, the first recess 310 and the second recess 510 can be used to store more electrolyte, which facilitates the circulation and consumption of electrolyte in the battery and improves the cycle performance of the battery.

[0065] In some embodiments, refer to Figure 1 and Figure 2 The size of the first coating layer 300 is not less than the size of the first active material layer 200, and the size of the first coating layer 300 is not greater than the size of the current collector 100. The size of the second coating layer 500 is not less than the size of the second active material layer 400, and the size of the second coating layer 500 is not greater than the size of the current collector 100.

[0066] Specifically, in this embodiment, the first coating layer 300 needs to completely cover the first active material layer 200 and the first groove 210, and the second coating layer 500 needs to completely cover the second active material layer 400 and the second groove 410, to prevent the first active material particles from falling off the outside of the first coating layer 300 and the second active material particles from falling off the outside of the second coating layer 500. Meanwhile, in order to reduce the overall volume of the electrode and increase its overall energy density, the coating area of ​​the first coating layer 300 needs to be less than or equal to the area of ​​the current collector 100, and the coating area of ​​the second coating layer 500 needs to be less than or equal to the area of ​​the current collector 100.

[0067] Preferably, the first coating layer 300 and the second coating layer 500 completely cover the entire electrode sheet. This not only effectively prevents active material particles from falling off the outside of the first coating layer 300 and the second coating layer 500, but also reduces burrs generated at the edge of the electrode sheet and in the empty foil area.

[0068] In some embodiments, refer to Figure 2 The first groove 210 satisfies the following relationship between the total groove volume V1 and the volume V2 of the first active material layer 200: 0.3% ≤ V1 / V2 ≤ 1%; the groove depth H1 and the thickness H2 of the first active material layer 200 satisfy the following relationship: 10% ≤ H1 / H2 ≤ 50%. The second groove 410 satisfies the following relationship between the total groove volume V3 and the volume V4 of the second active material layer 400: 0.3% ≤ V3 / V4 ≤ 1%; the groove depth H3 and the thickness H4 of the second active material layer 400 satisfy the following relationship: 10% ≤ H3 / H4 ≤ 50%.

[0069] Specifically, in this embodiment, by using the aforementioned numerical range, it is possible to ensure that a sufficient number of lithium-ion fast insertion channels are formed on the first active material layer 200 and the second active material layer 400, while also ensuring that the battery capacity is not lost. If the first groove 210 and the second groove 410 are set too small, for example, V1 / V2 < 0.3%, H1 / H2 < 10%, V3 / V4 < 0.3%, H3 / H4 < 10%, the number of lithium-ion fast insertion channels will decrease, and the improvement effect on the fast charging performance of the electrode will not be significant. If the first groove 210 and the second groove 410 are set too large, for example, V1 / V2 > 1%, H1 / H2 > 50%, V3 / V4 > 1%, H3 / H4 > 50%, the loss of the first active material layer 200 and the second active material layer 400 will be greater, which will reduce the capacity of the electrode.

[0070] In some embodiments, refer to Figure 2 Along the length direction of the electrode, the groove width L1 of the first groove 210 and the spacing L2 between two adjacent first grooves 210 satisfy the following condition: 1% ≤ L1 / L2 ≤ 5%. Along the length direction of the electrode, the groove width L3 of the second groove 410 and the spacing L4 between two adjacent second grooves 410 satisfy the following condition: 1% ≤ L3 / L4 ≤ 5%.

[0071] Specifically, in this embodiment, using the aforementioned numerical range is beneficial for uniformly distributing the first groove 210 on the first active material layer 200, preventing excessive concentration of lithium ions at a specific lithium ion rapid embedding channel in the first active material layer 200. Similarly, it is beneficial for uniformly distributing the second groove 410 on the second active material layer 400, preventing excessive concentration of lithium ions at a specific lithium ion rapid embedding channel in the second active material layer 400.

[0072] In some embodiments, refer to Figure 2 The thickness H5 of the first coating layer 300 and the thickness H2 of the first active material layer 200 satisfy the following relationship: 1% ≤ H5 / H2 ≤ 10%. The thickness H6 of the second coating layer 500 and the thickness H4 of the second active material layer 400 satisfy the following relationship: 1% ≤ H6 / H4 ≤ 10%.

[0073] Specifically, in this embodiment, by using the aforementioned numerical range, it can be ensured that the first coating layer 300 and the second coating layer 500 are within a suitable thickness. If the thickness of the first coating layer 300 is too thin, for example, H5 / H2 < 1%, the coverage effect on the first active material layer 200 is not significant, and the improvement effect on the K value of the electrode (K value refers to the voltage drop per unit time) is not significant. If the thickness of the first coating layer 300 is too thick, for example, H5 / H2 > 10%, it will lead to a significant increase in the thickness of the electrode, thereby reducing the energy density of the electrode. In addition, if the thickness of the first coating layer 300 is too thick, the lithium ions will have a long transmission distance when they are inserted and extracted on the electrode, which can easily degrade the electrode performance.

[0074] Similarly, if the thickness of the second coating layer 500 is too thin, for example, H6 / H4 < 1%, the coverage effect on the second active material layer 400 will be insignificant, and the improvement effect on the K value of the electrode (K value refers to the voltage drop per unit time) will be insignificant. If the thickness of the second coating layer 500 is too thick, for example, H6 / H4 > 10%, it will lead to a significant increase in the thickness of the electrode, thereby reducing the energy density of the electrode. In addition, if the thickness of the second coating layer 500 is too thick, the lithium ions will have to travel a long distance during insertion and extraction on the electrode, which can easily degrade the electrode performance.

[0075] In some embodiments, the first coating layer 300 is a composite structure composed of at least one of polyamide fiber, polyvinylidene fluoride, polymethyl methacrylate, and polyacrylate, and at least one of alumina, boehmite, magnesium oxide, magnesium hydroxide, silicon oxide, solid electrolyte, and lithium supplement. The second coating layer 500 is a composite structure composed of at least one of polyamide fiber, polyvinylidene fluoride, polymethyl methacrylate, and polyacrylate, and at least one of alumina, boehmite, magnesium oxide, magnesium hydroxide, silicon oxide, solid electrolyte, and lithium supplement.

[0076] Specifically, in this embodiment, the first coating layer 300 comprises a polymer material and an inorganic filler. The polymer material can be at least one of polyamide fiber, polyvinylidene fluoride, polymethyl methacrylate, and polyacrylate. The inorganic filler can be at least one of alumina, boehmite, magnesium oxide, magnesium hydroxide, silicon oxide, solid electrolyte, and lithium supplement. Similarly, the second coating layer 500 comprises a polymer material and an inorganic filler. The polymer material can be at least one of polyamide fiber, polyvinylidene fluoride, polymethyl methacrylate, and polyacrylate. The inorganic filler can be at least one of alumina, boehmite, magnesium oxide, magnesium hydroxide, silicon oxide, solid electrolyte, and lithium supplement.

[0077] Preferably, the first coating layer 300 or the second coating layer 500 is a polyacrylate and solid electrolyte coating. After the electrode is encapsulated to form a battery, the solid electrolyte can protect the active material particles at the perforated area from piercing the separator, and at the same time, the solid electrolyte can also act as an ion conductor to provide a channel for lithium ions to be inserted into the negative electrode, thereby improving the low-temperature performance of the battery.

[0078] Furthermore, in some embodiments, the ratio of polymeric material (which provides adhesion) to inorganic filler in the first coating layer 300 or the second coating layer 500 is within the range of: 1% ≤ polymeric material / inorganic filler ≤ 30%. The adhesive force between the first coating layer 300 and the first active material layer 200 is greater than the adhesive force between the first active material layer 200 and the current collector 100, and the adhesive force between the second coating layer 500 and the second active material layer 400 is greater than the adhesive force between the second active material layer 400 and the current collector 100. This ensures sufficient adhesion between the first coating layer 300 and the first active material layer 200, and between the second coating layer 500 and the second active material layer 400, preventing preferential detachment under external force. If the percentage of polymeric material / inorganic filler is less than 1%, there will be insufficient bonding strength between the first coating layer 300 and the first active material layer 200, and between the second coating layer 500 and the second active material layer 400. This can easily lead to the detachment of the first coating layer 300 and the second coating layer 500, which will worsen the K-value of the electrode (K-value refers to the voltage drop per unit time). If the percentage of polymeric material / inorganic filler is greater than 30%, the adhesive will fill the pores of the first coating layer 300 or the second coating layer 500, reducing the porosity of the first coating layer 300 or the second coating layer 500. This will make lithium-ion transport difficult and easily deteriorate the performance of the electrode. At the same time, if the adhesive content is high, at high temperatures (the temperature of the electrode will rise during operation), the adhesive will absorb electrolyte and swell, increasing the internal resistance of the battery and worsening the high-temperature performance of the battery.

[0079] Furthermore, in some embodiments, the particle size of the inorganic filler in the first coating layer 300 and the groove width of the first groove 210 (here, the distance between the opposite ends of the first groove 210 along the length of the electrode is defined as the groove width) satisfy the following ratio: 0.3% ≤ inorganic filler particle size / groove width ≤ 10%. Similarly, the particle size of the inorganic filler in the second coating layer 500 and the groove width of the second groove 410 (here, the distance between the opposite ends of the second groove 410 along the length of the electrode is defined as the groove width) also satisfy the following ratio: 0.3% ≤ inorganic filler particle size / groove width ≤ 10%. If the above ratio is too small, for example, if the inorganic filler particle size / groove width < 0.3%, the pore size of the first coating layer 300 or the second coating layer 500 is small, making the lithium ion insertion channel smaller and preventing the entry of lithium ions. If the above ratio is too large, for example, if the inorganic filler particle size / groove width is >10%, the inorganic filler cannot fill the first groove 210 or the second groove 410 well, and the coverage effect on the active material particles is not obvious.

[0080] Referring to Tables 1 to 3, comparative experiments were conducted to compare the effects of the improved electrode using comparative examples and implementation examples.

[0081] test Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 K value (mV / h) 0.02 0.02 0.02 0.02 Capacity (mAh) 5000 5000 4940 5000 Energy density (wh / L) 747 747 737 747 0℃ 0.2C discharge 91％ 91％ 91％ 87.9％ Lithium plating interface 1.8C Lithium plating 1.2C Lithium plating 2.0C Lithium plating 1.8C Lithium plating 10℃ cycle 86.9％ 87.0％ 87.1％ 87.0％ 45℃ cycle 79.6％ 79.6％ 80.0％ 80.1％ 55℃ 60mΩ 5 / 5 pass 5 / 5 pass 5 / 5 pass 5 / 5 pass Forced internal short circuit 5 / 5 pass 5 / 5 pass 5 / 5 pass 5 / 5 pass 131℃ Hot Box 5 / 5 pass 5 / 5 pass 5 / 5 pass 5 / 5 pass 132℃ Hot Box 5 / 5 pass 5 / 5 pass 5 / 5 pass 5 / 5 pass acupuncture 5 / 10 pass 5 / 10 pass 5 / 10 pass 5 / 10 pass

[0082] Table 1

[0083] test Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 K value (mV / h) 0.04 0.02 0.07 0.02 Capacity (mAh) 5000 4960 5000 4930 Energy density (wh / L) 749 734 747 737 0℃ 0.2C discharge 89.5％ 86.5％ 91％ 86％ Lithium plating interface 1.8C Lithium plating 1.3C Lithium plating 1.8C Lithium plating 1.3C Lithium plating 10℃ cycle 87％ 85％ 87.1％ 83％ 45℃ cycle 80％ 76％ 80.1％ 73％ 55℃ 60mΩ 3 / 5 pass 5 / 5 pass 3 / 5 pass 5 / 5 pass Forced internal short circuit 3 / 5 pass 5 / 5 pass 3 / 5 pass 5 / 5 pass 131℃ Hot Box 5 / 5 pass 5 / 5 pass 5 / 5 pass 5 / 5 pass 132℃ Hot Box 3 / 5 pass 5 / 5 pass 2 / 5 pass 5 / 5 pass acupuncture 2 / 10 pass 9 / 10 pass 3 / 10 pass 7 / 10 pass

[0084] Table 2

[0085] test Comparative Example 8 Comparative Example 9 Comparative Example 10 K value (mV / h) 0.02 0.035 0.06 Capacity (mAh) 5000 5000 5000 Energy density (Wh / L) 747 747 750 0℃ 0.2C discharge 91％ 91.2％ 88％ Lithium plating interface 1.3C Lithium plating 1.8C Lithium plating 1.8C Lithium plating 10℃ cycle 83％ 87.1％ 87％ 45℃ cycle 79.3％ 80.2％ 80％ 55℃ 60mΩ 5 / 5 pass 5 / 5 pass 0 / 5pass Forced internal short circuit 5 / 5 pass 5 / 5 pass 0 / 5pass 131℃ Hot Box 5 / 5 pass 5 / 5 pass 0 / 5pass 132℃ Hot Box 5 / 5 pass 5 / 5 pass 0 / 5pass acupuncture 6 / 10 pass 3 / 10 pass 0 / 10 pass

[0086] Table 3

[0087] In Example 1, the fabrication of the electrode includes at least the following steps:

[0088] Step 1: Stirring of the negative electrode active material.

[0089] Graphite, conductive agent, sodium carboxymethyl cellulose, and styrene-butadiene rubber are added to a mixing tank in a specific order with water at a mass ratio of 96:1:1:2. The mixture is stirred at a specific speed and for a specific time until homogeneous to obtain a negative electrode slurry.

[0090] Step 2: Coating and rolling of the negative electrode active material coating.

[0091] The negative electrode slurry is uniformly coated onto the surface of copper foil (current collector), and then baked in an oven at 110°C to obtain an electrode sheet with a negative electrode active material layer. The electrode sheet with the negative electrode active material layer is then rolled, and the thickness of the active material layer after rolling is 60 μm.

[0092] Step 3: Drill holes on the surface of the negative electrode active material layer.

[0093] Using a laser drilling device, some of the active material on the surface of the negative electrode is detached under the action of a laser to form grooves. At this time, the width of the groove is 50um, the depth of the groove is 20um, and the distance between two adjacent grooves is 2000um. The drilling width is the same as the width of the negative electrode sheet. At this time, the volume of the groove in the repeating unit accounts for the volume of the active material layer in the repeating unit as: (20*50) / (60*(2000+50))=0.8%.

[0094] Step 4: Mix the coating layer.

[0095] A polyacrylic adhesive and lithium aluminum titanium phosphate (solid electrolyte) were added to a mixing tank in a 10:90 ratio along with water in a specific order. The mixture was stirred at a controlled speed and for a set time until homogeneous to obtain the coating slurry. The lithium aluminum titanium phosphate used had a Dv50 of 0.3 μm.

[0096] Step 5: Coating the coating layer and cutting the electrode sheets.

[0097] The uniformly stirred coating layer was applied to the surface of the perforated negative electrode active material layer using a gravure coating process. After drying, the electrode sheet containing the coating layer was obtained. The coating layer thickness was 2 μm. The coated electrode sheet was then cut into the required width to obtain a negative electrode sheet without solder tabs.

[0098] Step 6: Preparation of positive electrode sheet.

[0099] Lithium cobalt oxide, polyvinylidene fluoride, and conductive carbon black were added to a mixing tank in a specific weight ratio of 97:1:2 along with NMP to prepare a cathode slurry. The slurry was then extruded and coated evenly onto aluminum foil (current collector). After drying, the slitting process was used to produce positive electrode sheets with welded tabs.

[0100] Step 7: Electrode welding and winding.

[0101] Positive and negative electrode sheets are prepared by fabricating, welding tabs, and applying adhesive. These sheets are then wound with a separator to form a bare battery cell. The bare battery cell is then encapsulated in an aluminum-plastic film and subjected to baking, electrolyte injection, formation, resealing, and aging to obtain the final battery cell.

[0102] In Comparative Example 1, steps 1 to 2, and steps 4 to 7 are the same as those in Example 1, except for step 3.

[0103] Step 3 in Comparative Example 1 is as follows: Using a laser drilling device, some of the active material on the surface of the negative electrode is detached under the action of the laser to form a groove. At this time, the width of the groove is 40 μm, the depth of the groove is 9 μm, and the distance between two adjacent grooves is 2000 μm. The drilling width is the same as the width of the negative electrode sheet. At this time, the volume of the groove in the repeating unit accounts for the volume of the active material layer in the repeating unit as: (9*30) / (60*(2000+30))=0.22%.

[0104] In Comparative Example 2, steps 1 to 2, and steps 4 to 7 are the same as those in Example 1, except for step 3.

[0105] Step 3 in Comparative Example 2 is as follows: Using a laser drilling device, some of the active material on the surface of the negative electrode is detached under the action of the laser to form a groove. At this time, the width of the groove is 80 μm, the depth of the groove is 25 μm, and the distance between two adjacent grooves is 2000 μm. The drilling width is the same as the width of the negative electrode sheet. At this time, the volume of the groove in the repeating unit accounts for the volume of the active material layer in the repeating unit as: (25*80) / (60*(2000+80))=1.6%.

[0106] In Comparative Example 3, steps 1 to 3, and steps 5 to 6 are the same as those in Example 1, except for step 4.

[0107] Step 4 in Comparative Example 3 involves adding polyacrylic adhesive and boehmite in a 10:90 ratio to water in a specific order into a mixing tank. The mixture is then stirred at a controlled speed and for a set time until homogeneous, yielding the coating slurry. The boehmite used has a Dv50 of 0.3 μm.

[0108] In Comparative Example 4, steps 1 to 4, and steps 6 to 7 are the same as those in Example 1, except for step 5.

[0109] Step 5 in Comparative Example 4 involves: applying the uniformly stirred coating layer to the surface of the perforated negative electrode active material layer using a gravure coating process; drying the electrode to obtain an electrode containing the coating layer. The coating layer thickness is 0.5 μm. The coated electrode is then cut into the required width to obtain a negative electrode without soldered tabs.

[0110] In Comparative Example 5, steps 1 to 4, and steps 6 to 7 are the same as those in Example 1, except for step 5.

[0111] Step 5 in Comparative Example 5 is as follows: The uniformly stirred coating layer is coated onto the surface of the perforated negative electrode active material layer using a gravure coating process. After the electrode is dried, an electrode containing the coating layer is obtained. The coating layer thickness is 7 μm. The electrode with the coating layer is cut into the required width to obtain a negative electrode without soldered tabs.

[0112] In Comparative Example 6, steps 1 to 3, and steps 5 to 7 are the same as those in Example 1, except for step 4.

[0113] Step 4 in Comparative Example 6 involves adding polyacrylic adhesive and lithium titanium aluminum phosphate (solid electrolyte) to a mixing tank in a ratio of 0.5:99.5 and water in a specific order. The mixture is then stirred at a controlled speed and for a set time until homogeneous, yielding the coating slurry. The lithium titanium aluminum phosphate used has a Dv50 of 0.3 μm.

[0114] In Comparative Example 7, steps 1 to 3, and steps 5 to 7 are the same as those in Example 1, except for step 4.

[0115] Step 4 in Comparative Example 7 involves adding polyacrylic adhesive and lithium titanium aluminum phosphate (solid electrolyte) to a mixing tank in a 25:75 ratio along with water in a specific order. The mixture is then stirred at a controlled speed and for a set time until homogeneous, resulting in a coating slurry. The lithium titanium aluminum phosphate used has a Dv50 of 0.3 μm.

[0116] In Comparative Example 8, steps 1 to 3, and steps 5 to 7 are the same as those in Example 1, except for step 4.

[0117] Step 4 in Comparative Example 8 involves adding polyacrylic adhesive and lithium titanium aluminum phosphate (solid electrolyte) to a mixing tank in a 10:90 ratio along with water in a specific order. The mixture is then stirred at a controlled speed and for a set time until homogeneous, resulting in a coating slurry. The lithium titanium aluminum phosphate used has a Dv50 of 0.15 μm.

[0118] In Comparative Example 9, steps 1 to 3, and steps 5 to 7 are the same as those in Example 1, except for step 4.

[0119] Step 4 in Comparative Example 9 involves adding polyacrylic adhesive and lithium titanium aluminum phosphate (solid electrolyte) in a 10:90 ratio to water in a specific order into a mixing tank. The mixture is then stirred at a controlled speed and for a set time until homogeneous, resulting in a coating slurry. The lithium titanium aluminum phosphate used has a Dv50 of 5µm.

[0120] In Comparative Example 10, steps 1 to 3, and steps 5 to 7 are the same as those in Example 1, except that the electrode in Comparative Example 10 is not coated with a film layer.

[0121] After the above embodiments and comparative examples were fabricated into battery cells, the K-value, capacity, volumetric energy density, 0℃ 0.2C low-temperature discharge, lithium plating interface, 10℃ low-temperature cycling (1000 cycles) and 45℃ high-temperature cycling (800 cycles), 55℃ 60mΩ high-temperature external short circuit, forced internal short circuit, hot box, and needle penetration were all tested using the same method. The test results are shown in Tables 1 to 3.

[0122] As can be seen from the comparison between Example 1 and Comparative Examples 1, 2, and 10, the presence of the coating layer can significantly improve the cell's K-value, 55℃ 60mΩ external short circuit, forced internal short circuit, hot box, and needle penetration. Furthermore, when the volume of the groove within a repeating cell accounts for 0.3% to 1% of the volume of the active material layer within the repeating cell, it can meet higher charging rate requirements and improve the low-temperature lithium plating interface. When the ratio is less than 0.3%, it worsens the low-temperature charging lithium plating interface; when the ratio is greater than 1%, it worsens the cell capacity and energy density.

[0123] As can be seen from the comparison of the test results of Example 1, Comparative Examples 3 and 10, the effect of using solid electrolyte in the coating layer is better than that of boehmite. When the coating layer contains solid electrolyte, in addition to improving K value, 55℃ 60mΩ external short circuit, forced internal short circuit, hot box, and needle penetration, it can also improve 0℃ 0.2C discharge.

[0124] As can be seen from the comparison of Example 1, Comparative Examples 4 and 5, the effect is best when the "coating thickness / active material coating thickness" ranges from 1% to 10%. When the ratio is <1%, the improvement on K value, 55℃ 60mΩ external short circuit, forced internal short circuit, hot box, and needle penetration is not obvious. When the ratio is >10%, the energy density deteriorates significantly and the low-temperature lithium plating interface will also be worsened.

[0125] As can be seen from the comparison of Examples 1, 6, and 7, when the ratio of polymer material to inorganic filler is <1%, the surface coating layer is prone to peeling off, which worsens the K value. The improvement on external short circuit, forced internal short circuit, hot box, and needle penetration at 55℃ and 60mΩ is not significant. When the ratio is >30%, the cell dynamics are worsened, and the cell discharge capacity, energy density, low temperature discharge at 0℃ and 0.2C, and low temperature and high temperature cycling are reduced. However, the improvement on external short circuit, forced internal short circuit, hot box, and needle penetration at 55℃ and 60mΩ is significant.

[0126] As can be seen from the comparison of Example 1, Comparative Examples 8 and 9, when the ratio of "inorganic filler particle size / perforation width < 0.3%", the low-temperature discharge at 0°C and 0.2°C and the low-temperature cycling performance are worsened. When the ratio is greater than 10%, the improvement effect on the K value of the battery cell is not significant.

[0127] Correspondingly, another embodiment of this utility model also provides a battery cell, which includes the electrode, separator, and encapsulation shell as described in the above embodiments. The electrode includes at least a positive electrode and a negative electrode, and the positive and negative electrode are stacked. The separator is disposed between the two electrode pieces, and the encapsulation shell has a receiving cavity, in which the electrode and the separator are disposed.

[0128] Specifically, in this embodiment, the battery cell using the aforementioned electrode sheet can ensure both improved fast charging speed and safe use.

[0129] Correspondingly, another embodiment of this utility model also provides an electronic device that includes the aforementioned battery cell. For example, the electronic device may be a mobile phone, a laptop computer, a camera, etc.

[0130] Specifically, in this embodiment, electronic devices using the aforementioned battery cells can ensure both improved fast charging speed and safe operation.

[0131] Thanks to the improvements in the aforementioned electrode plates, the battery cell and electronic device of this embodiment have the same technical effects as the aforementioned electrode plates, which will not be repeated here.

[0132] It should be noted that other contents of the electrode sheet, battery cell and electronic device disclosed in this utility model can be found in the prior art, and will not be repeated here.

[0133] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural transformations made based on the inventive concept of this utility model and the contents of this utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this utility model.

Claims

1. An electrode, characterized in that, include: A current collector having a first surface; A first active material layer is disposed on the first surface, and a plurality of first grooves are provided at intervals on the side of the first active material layer away from the current collector. A first coating layer is disposed on the side of the first active material layer away from the current collector, and the first coating layer is embedded in the first groove.

2. The electrode sheet according to claim 1, characterized in that, The current collector has a second surface disposed opposite to the first surface. The second surface is provided with a second active material layer. A plurality of second grooves are provided at intervals on the side of the second active material layer away from the current collector. A second coating layer is provided on the side of the second active material layer away from the current collector. The second coating layer is embedded in the second grooves.

3. The electrode sheet according to claim 2, characterized in that, The first coating layer has a first recess on the side away from the first active substance layer, and the second coating layer has a second recess on the side away from the second active substance layer.

4. The electrode sheet according to claim 2, characterized in that, The size of the first coating layer is not less than the size of the first active material layer, and the size of the first coating layer is not greater than the size of the current collector; The size of the second coating layer is not less than the size of the second active material layer, and the size of the second coating layer is not greater than the size of the current collector.

5. The electrode sheet according to claim 2, characterized in that, The total groove volume V1 of the first groove on the first active material layer and the volume V2 of the first active material layer satisfy the following: 0.3% ≤ V1 / V2 ≤ 1%; the groove depth H1 of the first groove and the thickness H2 of the first active material layer satisfy the following: 10% ≤ H1 / H2 ≤ 50%. The total groove volume V3 on the second active material layer and the volume V4 of the second active material layer satisfy the following: 0.3% ≤ V3 / V4 ≤ 1%; the groove depth H3 of the second groove and the thickness H4 of the second active material layer satisfy the following: 10% ≤ H3 / H4 ≤ 50%.

6. The electrode sheet according to claim 2, characterized in that, Along the length direction of the electrode sheet, the groove width L1 of the first groove and the spacing L2 between two adjacent first grooves satisfy the following: 1% ≤ L1 / L2 ≤ 5%. Along the length of the electrode, the groove width L3 of the second groove and the spacing L4 between two adjacent second grooves satisfy the following condition: 1% ≤ L3 / L4 ≤ 5%.

7. The electrode sheet according to claim 2, characterized in that, The thickness H5 of the first coating layer and the thickness H2 of the first active material layer satisfy the following: 1% ≤ H5 / H2 ≤ 10%; The thickness H6 of the second coating layer and the thickness H4 of the second active material layer satisfy the following condition: 1% ≤ H6 / H4 ≤ 10%.

8. A battery cell, characterized in that, include: At least two electrodes as described in any one of claims 1 to 7, wherein the two electrodes are stacked together; A diaphragm is disposed between the two electrodes; The encapsulation housing has a receiving cavity, and the electrode and the diaphragm are disposed within the receiving cavity.

9. An electronic device, characterized in that, Includes the battery cell as described in claim 8.

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