Scribed electrode plate, bare cell and battery

Abstract

The present application relates to the technical field of energy storage devices, and particularly relates to a scribed electrode plate, a bare battery cell and a battery. The scribed electrode plate has an active material layer on at least one side in the thickness direction of the scribed electrode plate, and the active material layer contains a silicon-based active substance. The scribed electrode plate has an inner ring region at one end in the length direction of the scribed electrode plate, and the scribed electrode plate is used to wind to form a bare battery cell, and the inner ring region corresponds to an inner ring of the bare battery cell. The outer surface of the active material layer in the inner ring region has first scribe lines, the depth direction of the first scribe lines is parallel to the thickness direction of the scribed electrode plate, the first scribe lines are X-shaped structures, and the included angle alpha between any one scribe line of the X-shaped structure and the width direction of the scribed electrode plate is in the range of 7.5-30 degrees. The bare battery cell comprises the scribed electrode plate, and the battery comprises a shell and the bare battery cell, and the bare battery cell is arranged in the shell. The scribed electrode plate, the bare battery cell and the battery have higher anti-expansion capability, lower backflow resistance of electrolyte, and higher cycle stability and use safety.

Description

Technical Field

[0001] This invention relates to the field of energy storage equipment technology, and in particular to a scribed electrode, a bare cell, and a battery. Background Technology

[0002] To improve battery life, lithium-ion cylindrical batteries commonly employ thick coating and high-pressure compaction processes, which leads to the collapse of internal pores in the electrode sheets and obstruction of electrolyte wetting channels. While introducing silicon-based materials can effectively suppress electrode thickness growth, the significant volume expansion of silicon-based materials, combined with the initial stress generated by high-pressure compaction, results in high stress concentration in the inner ring of the wound bare cell. This region has weak resistance to expansion, leading to greater resistance to electrolyte reflux after expansion, significant electrolyte hysteresis, and a high risk of exacerbating concentration polarization and interfacial side reactions, severely deteriorating high-rate discharge performance and long-cycle stability. Summary of the Invention

[0003] One objective of this invention is to provide a scribed electrode sheet that can help improve the anti-expansion capability of the inner ring of the bare cell, reduce the backflow resistance of the electrolyte, reduce the polarization effect under high-rate charge and discharge, suppress lithium plating on the negative electrode, and improve the cycle stability and safety of the battery.

[0004] To achieve this objective, the present invention adopts the following technical solution: A scribed electrode is provided, wherein at least one side of the scribed electrode along its thickness direction has an active material layer containing a silicon-based active substance, and one end of the scribed electrode along its length direction has an inner ring region. The scribed electrode is used to wind and form a bare battery cell, and the inner ring region corresponds to the inner ring of the bare battery cell. The outer surface of the active material layer in the inner ring region has a first scribed line, the depth direction of the first scribed line is parallel to the thickness direction of the scribed electrode, and the first scribed line is an X-shaped structure. The angle α between any scribed line of the X-shaped structure and the width direction of the scribed electrode ranges from 7.5° to 30°.

[0005] Optionally, the line width K1 of any scribe line of the X-shaped structure satisfies: 5s×d 50 ≥K1≥0.5s×d 50 , where d 50 The average particle size of the silicon-based active material is given, and s% is the mass percentage of the silicon-based active material in the etched electrode.

[0006] Optionally, the depth D1 of any scribe line of the X-shaped structure satisfies: D1 ≥ 2 × d 50 , where d 50 The average particle size of the silicon-based active material; And / or, the thickness of the etched electrode is D, and the depth D1 of any etched line of the X-shaped structure satisfies: 0.3≥D1 / D≥0.1.

[0007] Optionally, the intersection of the two scribe lines of the X-shaped structure is located on the center line of the width direction of the scribe line electrode.

[0008] Optionally, the etched electrode further has an outer ring region, which is adjacent to the inner ring region. The outer ring region corresponds to the outer ring of the bare cell. The outer surface of the active material layer in the outer ring region has a second etched line. The depth direction of the second etched line is parallel to the thickness direction of the etched electrode, and the second etched line extends along the width direction of the etched electrode.

[0009] Optionally, the line width K2 of the second scribe line satisfies: 5s×d 50 ≥K2≥0.5s×d 50 , where d 50 The average particle size of the silicon-based active material is given, and s% is the mass percentage of the silicon-based active material in the etched electrode.

[0010] Optionally, the depth D1 of any one of the X-shaped lines and the depth D2 of the second line satisfy: 3≥D1 / D2≥1.5; And / or, the depth D2 of the second etch line satisfies: D2 ≥ 2 × d 50 , where d 50 The average particle size of the silicon-based active material; And / or, the thickness of the etched electrode is D, and the depth D2 of the second etched line satisfies: 0.2≥D2 / D≥0.05.

[0011] Optionally, in the inner ring region, multiple first scribe lines are sequentially arranged along the length direction of the scribe line electrode; in the outer ring region, multiple second scribe lines are sequentially arranged along the length direction of the scribe line electrode; the distance between the intersection positions of two adjacent X-shaped structures along the length direction of the scribe line electrode is S1; the distance between two adjacent second scribe lines along the length direction of the scribe line electrode is S2, satisfying: S2 / S1≥1.5; And / or, along the length direction of the etched electrode, the length of the inner ring region is L1, and the total length of the etched electrode is L, satisfying: 0.3≥L1 / L≥0.15.

[0012] Another objective of this invention is to provide a bare battery cell that can help improve the anti-expansion capability of the inner ring, reduce the backflow resistance of the electrolyte, reduce the polarization effect under high-rate charge and discharge, suppress lithium plating on the negative electrode, and improve the cycle stability and safety of the battery.

[0013] To achieve this objective, the present invention adopts the following technical solution: A bare battery cell is provided, comprising the aforementioned etched electrode plates.

[0014] Another objective of this invention is to provide a battery with higher resistance to expansion at the inner ring of the bare cell, which can reduce the backflow resistance of the electrolyte, reduce the polarization effect under high-rate charge and discharge, suppress lithium plating at the negative electrode, and improve the cycle stability and safety of the battery.

[0015] To achieve this objective, the present invention adopts the following technical solution: A battery is provided, including a housing and the aforementioned bare cell, wherein the bare cell is disposed within the housing.

[0016] The beneficial effects of this invention are: This invention provides a etched electrode sheet, wherein at least one side of the etched electrode sheet along its thickness direction has an active material layer containing a silicon-based active material. One end of the etched electrode sheet along its length direction has an inner ring region. The etched electrode sheet is used to wind and form a bare battery cell, and the inner ring region corresponds to the inner ring of the bare battery cell. The outer surface of the active material layer within the inner ring region has a first etched line. The depth direction of the first etched line is parallel to the thickness direction of the etched electrode sheet. The first etched line has an X-shaped structure, and the angle α between any etched line of the X-shaped structure and the width direction of the etched electrode sheet ranges from 7.5° to 30°. By creating the first etched line of the X-shaped structure at the position of the etched electrode sheet corresponding to the inner ring of the bare battery cell, the stress field can be reconstructed, improving the expansion resistance of the inner ring and enhancing the initial electrolyte retention capacity of the inner ring of the bare battery cell. It can also reduce the electrolyte backflow resistance, thereby helping to avoid local electrolyte depletion in the later stages of cycling, reducing polarization effects under high-rate charge and discharge, suppressing lithium plating on the negative electrode, and improving the cycle stability and safety of the battery. Furthermore, by limiting the range of the angle α between any scribe line of the X-shaped structure and the width direction of the scribe electrode, i.e. the scribe line will not tend towards the length direction of the scribe electrode, stress concentration at the scribe line during expansion can be prevented to avoid cracking, thus preventing the battery's actual capacity from decreasing and the current stability from deteriorating.

[0017] The present invention also provides a bare battery cell, including the aforementioned etched electrode. This bare battery cell can help improve the anti-expansion capability of the inner ring, reduce the backflow resistance of the electrolyte, reduce the polarization effect under high-rate charge and discharge, suppress lithium plating on the negative electrode, and improve the cycle stability and safety of the battery.

[0018] The present invention also provides a battery, including a casing and the aforementioned bare cell, wherein the bare cell is disposed within the casing. This battery exhibits higher resistance to expansion at the inner ring of the bare cell, reducing electrolyte backflow resistance, decreasing polarization effects under high-rate charge and discharge, suppressing lithium plating at the negative electrode, and improving the battery's cycle stability and safety. Attached Figure Description

[0019] Figure 1 This is a first-view structural schematic diagram of the scribed electrode sheet provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the second perspective of the scribed electrode sheet provided in an embodiment of the present invention.

[0020] In the picture: 10. Active material layer; 20. Current collector; 1. Inner circle area; 11. First engraving line; 2. Outer ring area; 21. Second engraving line. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings, not all of them.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0023] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0024] To improve battery life, lithium-ion cylindrical batteries commonly employ thick coating and high-pressure compaction processes, which leads to the collapse of internal pores in the electrode sheets and obstruction of electrolyte wetting channels. While introducing silicon-based materials can effectively suppress electrode thickness growth, the significant volume expansion of silicon-based materials, combined with the initial stress generated by high-pressure compaction, results in high stress concentration in the inner ring of the wound bare cell. This region has weak resistance to expansion, leading to greater resistance to electrolyte reflux after expansion, significant electrolyte hysteresis, and a high risk of exacerbating concentration polarization and interfacial side reactions, severely deteriorating high-rate discharge performance and long-cycle stability.

[0025] Therefore, this embodiment provides a scribed electrode to solve the above problems. The scribed electrode can help improve the anti-expansion ability of the inner ring of the bare cell, reduce the backflow resistance of the electrolyte, reduce the polarization effect under high-rate charge and discharge, suppress the lithium plating phenomenon of the negative electrode, and improve the cycle stability and safety of the battery.

[0026] like Figures 1-2 As shown, in this embodiment, the etched electrode has an active material layer 10 on at least one side along its thickness direction, and the active material layer 10 contains a silicon-based active material. One end of the etched electrode along its length direction has an inner ring region 1. The etched electrode is used to wind and form a bare battery cell, and the inner ring region 1 corresponds to the inner ring of the bare battery cell. The outer surface of the active material layer 10 within the inner ring region 1 has a first etched line 11. The depth direction of the first etched line 11 is parallel to the thickness direction of the etched electrode. The first etched line 11 has an X-shaped structure, and the angle α between any etched line of the X-shaped structure and the width direction of the etched electrode ranges from 7.5° to 30°.

[0027] The first scribe line 11, with an X-shaped structure, is located at the inner ring of the bare cell, reserving a small deformation space. This buffers the expansion and compression forces of the inner ring region 1 during charging and discharging, reconstructs the stress field, and improves the expansion resistance of the inner ring region 1. The first scribe line 11 also helps improve the electrolyte retention capacity of the inner ring of the bare cell initially, reducing the electrolyte backflow resistance during subsequent use. This helps avoid local electrolyte depletion in the later stages of cycling, reduces polarization effects under high-rate charging and discharging, avoids lithium plating on the negative electrode, and improves the cycle stability and safety of the battery. The curvature of the inner ring region 1 of the bare cell is much higher than that of the outer ring region 2. The first scribe line 11 can offset the tensile or compressive stress of the coating caused by the bending of the scribe line electrode, preventing a decrease in coating adhesion and the appearance of microcracks in the inner ring region 1.

[0028] By limiting the range of the angle α between any scribe line of the X-shaped structure and the width direction of the scribe electrode, i.e., the scribe line will not tend towards the length direction of the scribe electrode, stress concentration at the scribe line during expansion can be prevented from causing cracks, thus preventing the battery's actual capacity from decreasing and the current stability from deteriorating.

[0029] Optionally, in this embodiment, the etched electrode has active material layers 10 on both sides along its thickness direction, and both active material layers 10 contain silicon-based active materials. The current collector 20 is located between the two active material layers 10, and the two active material layers 10 are mirror-symmetrically arranged, that is, the first etched line 11 with an X-shaped structure is provided on the side of each active material layer 10 facing away from the current collector 20.

[0030] Optionally, the line width K1 of any scribe line in the X-shaped structure satisfies: 5s×d 50 ≥K1≥0.5s×d 50 , where d 50 Here, s% represents the average particle size of the silicon-based active material, and s% represents the mass percentage of the silicon-based active material in the etched electrode. The mass percentage of the silicon-based active material in the etched electrode is generally greater than or equal to 8%, meaning s is generally greater than or equal to 8. Therefore, the above conditions require that the linewidth K1 of any etched line in the X-type structure needs to be greater than or equal to 4 times the average particle size of the silicon-based active material. This prevents the silicon-based active material particles from expanding several times their original size and filling the etched line, thus weakening the effect of the etched line in alleviating electrolyte reflux resistance. Furthermore, when the mass percentage of the silicon-based active material in the etched electrode is constant, the larger the average particle size of the silicon-based active material in the etched electrode, the larger the size of the silicon-based active material after expanding several times, and the larger the linewidth of the etched line needs to be. When the average particle size of the silicon-based active material in the etched electrode is constant, the more silicon-based active material the etched electrode contains, the greater the possibility that multiple silicon-based active material particles will expand and connect at the etched line to collectively block it. Therefore, the linewidth of the etched line also needs to be increased accordingly to ensure the effect of alleviating electrolyte reflux resistance. At the same time, the line width K1 of any scribe line in the X-shaped structure cannot exceed 5s×d. 50 The mass percentage of silicon-based active material in the etched electrode is generally less than or equal to 20%, and the average particle size of the silicon-based active material is generally less than or equal to 20μm. That is, the line width K1 of any etched line in the X-type structure cannot be greater than 2000μm, so as to avoid excessive capacity loss of the bare cell. In addition, if the line width K1 of any etched line in the X-type structure is too large, it will also reduce the mechanical strength of the etched electrode and shorten the service life of the bare cell.

[0031] Optionally, the line width K1 of any scribe line in the X-shaped structure can be 0.5s×d. 50 ,s×d 50 1.5s×d 50 2s×d 50 2.5s×d 50 3s×d 50 3.5s×d 50 4s×d 50 4.5s×d 50 or 5s×d 50 .

[0032] Optionally, the line width K1 of any scribe line in the X-shaped structure cannot exceed 1000μm, in order to further reduce the capacity loss of the bare cell and prevent cracking at the first scribe line 11.

[0033] Optionally, the average particle size d of the silicon-based active material 50 The value range is 5μm-20μm.

[0034] Optionally, in some embodiments, the mass percentage of silicon-based active material in the etched electrode ranges from 8% to 20%.

[0035] Optionally, the depth D1 of any scribe line of the X-shaped structure satisfies: D1 ≥ 2 × d 50 , where d 50 The average particle size of the silicon-based active material remains constant. The depth D1 of any scribe line in the X-shaped structure must be greater than or equal to 10 μm to prevent the silicon-based active material particles from expanding to several times their original size and filling the scribe line, which would weaken the effect of the scribe line in relieving electrolyte reflux resistance.

[0036] Optionally, the thickness of the etched electrode is D, and the depth D1 of any etched line in the X-type structure satisfies: 0.3 ≥ D1 / D ≥ 0.1. If the ratio of the depth D1 of any etched line in the X-type structure to the thickness D of the etched electrode is less than 0.1, then when the thickness D of the etched electrode is constant, the depth D1 of any etched line in the X-type structure is too small, which cannot ensure that the surface of the silicon-based active material is effectively exposed at the etched line, and the internal expansion of the silicon-based active material will still cause large stress. If the ratio of the depth D1 of any etched line in the X-type structure to the thickness D of the etched electrode is greater than 0.3, then when the thickness D of the etched electrode is constant, the depth D1 of any etched line in the X-type structure is too large, and excessive etching will cause excessive capacity loss, and the material is easily damaged, resulting in insufficient bonding between material layers.

[0037] Optionally, in this embodiment, the thickness D of the scribed electrode ranges from 70 μm to 150 μm. Correspondingly, the depth D1 of any scribed line of the X-shaped structure ranges from 7 μm to 45 μm.

[0038] Optionally, the depth D1 of any scribe line of the X-shaped structure is 7μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm or 45μm.

[0039] Optionally, the intersection of the two scribe lines of the X-shaped structure is located on the center line of the width direction of the scribe line electrode, which can ensure that the stress distribution on both sides of the scribe line electrode is relatively balanced along the width direction.

[0040] Optionally, the two scribe lines of the X-shaped structure are symmetrically arranged with reference to the line passing through the intersection of the two lines along the width direction of the scribe line electrode. This can also ensure that the stress at the two scribe lines is relatively balanced, avoiding the problem of severely uneven stress distribution or excessive stress concentration.

[0041] Optionally, the etched electrode also has an outer ring region 2, which is adjacent to the inner ring region 1. The outer ring region 2 corresponds to the outer ring of the bare cell. The outer surface of the active material layer 10 in the outer ring region 2 has a second etched line 21. The depth direction of the second etched line 21 is parallel to the thickness direction of the etched electrode, and the second etched line 21 extends along the width direction of the etched electrode. That is, the outer ring region 2 can guide the stress release during the expansion of the bare cell through the second etched line 21, avoiding irregular wrinkles in the outer ring region 2 and reducing problems such as coating peeling and cracking caused by the expansion of the silicon-based negative electrode.

[0042] Optionally, the line width K2 of the second etch line 21 satisfies: 5s×d 50 ≥K2≥0.5s×d 50 , where d 50 Here, s represents the average particle size of the silicon-based active material, and s% represents the mass percentage of the silicon-based active material in the etched electrode. The mass percentage of the silicon-based active material in the etched electrode is generally greater than or equal to 8%, meaning s is generally greater than or equal to 8. Therefore, the above conditions require that the linewidth K2 of the second etch 21 be greater than or equal to 4 times the average particle size of the silicon-based active material. This prevents the silicon-based active material particles from expanding several times in size and filling the second etch 21, thus weakening the effect of the second etch 21 in alleviating electrolyte reflux resistance. Furthermore, when the mass percentage of the silicon-based active material in the etched electrode is constant, the larger the average particle size of the silicon-based active material contained in the etched electrode, the larger the size of the silicon-based active material after expanding several times, and the larger the linewidth of the second etch 21 needs to be. When the average particle size of the silicon-based active material contained in the etched electrode is constant, a larger amount of silicon-based active material in the etched electrode increases the likelihood that multiple silicon-based active material particles will expand and connect at the second etched line 21 to collectively block it. Therefore, the linewidth of the second etched line 21 also needs to be increased accordingly to ensure the effect of alleviating the electrolyte backflow resistance. Simultaneously, the linewidth K2 of the second etched line 21 cannot exceed 5s×d. 50 The mass percentage of silicon-based active material in the etched electrode is generally less than or equal to 20%, and the average particle size of the silicon-based active material is generally less than or equal to 20μm. That is, the line width K2 of the second etched line 21 cannot be greater than 2000μm, so as to avoid excessive capacity loss of the bare cell. In addition, if the line width K2 of the second etched line 21 is too large, it will also reduce the mechanical strength of the etched electrode and shorten the service life of the bare cell.

[0043] Optionally, the line width K2 of the second scribe line 21 can be 0.5s×d. 50 ,s×d 501.5s×d 50 2s×d 50 2.5s×d 50 3s×d 50 3.5s×d 50 4s×d 50 4.5s×d 50 or 5s×d 50 .

[0044] Optionally, the line width K2 of the second scribe line 21 shall not exceed 1000μm in order to further reduce the capacity loss of the bare cell and prevent cracking at the second scribe line 21.

[0045] Optionally, the depth D2 of the second scribe line 21 satisfies: D2 ≥ 2 × d 50 , where d 50 The average particle size of the silicon-based active material is given. The depth D2 of the second scribe line 21 needs to be greater than or equal to 10 μm to prevent the silicon-based active material particles from expanding to several times their original size and filling the second scribe line 21, which would weaken the effect of the second scribe line 21 in relieving electrolyte reflux resistance.

[0046] Optionally, the thickness of the etched electrode is D, and the depth D2 of the second etched line 21 satisfies: 0.2 ≥ D2 / D ≥ 0.05. If the ratio of the depth D2 of the second etched line 21 to the thickness D of the etched electrode is less than 0.05, then when the thickness D of the etched electrode is constant, the depth D2 of the second etched line 21 is too small, which cannot ensure that the surface of the silicon-based active material is effectively exposed at the etched line, and the internal expansion of the silicon-based active material will still cause large stress. If the ratio of the depth D2 of the second etched line 21 to the thickness D of the etched electrode is greater than 0.2, then when the thickness D of the etched electrode is constant, the depth D2 of the second etched line 21 is too large, and excessive etching will cause excessive capacity loss, and the material is easily damaged, resulting in insufficient bonding between material layers.

[0047] Optionally, in this embodiment, the thickness D of the etched electrode ranges from 70 μm to 150 μm. Correspondingly, the depth D2 of the second etched line 21 ranges from 3.5 μm to 30 μm.

[0048] Optionally, the depth D2 of the second scribe line 21 is 3.5μm, 10μm, 15μm, 20μm, 25μm or 30μm.

[0049] Optionally, the depth D1 of any scribe line and the depth D2 of the second scribe line 21 in the X-shaped structure satisfy: 3 ≥ D1 / D2 ≥ 1.5. That is, the scribe line depth in the inner region 1 is deeper, and the scribe line depth in the outer region 2 is shallower. The ratio of the depth D1 of any scribe line and the depth D2 of the second scribe line 21 in the X-shaped structure conforms to the above-mentioned value range, which can better adapt to the actual needs of the inner region 1 having a higher curvature than the outer region 2 and greater stress in the inner region 1. However, if the ratio of the depth D1 of any scribe line and the depth D2 of the second scribe line 21 in the X-shaped structure is less than 1.5, the difference between the two is too small, which may result in the depth of the first scribe line 11 in the inner region 1 being insufficient to effectively improve the stress and backflow problems, or the depth of the second scribe line 21 in the outer region 2 being too large, so that while effectively improving the stress problem, the depth can be reduced to reduce the capacity loss of the scribe line electrode. If the ratio of the depth D1 of any scribe line 21 to the depth D2 of the second scribe line 21 in the X-shaped structure is greater than 3, then the difference between the two is too large. This may result in the first scribe line 11 in the inner ring region 1 being too deep, leading to excessive capacity loss of the scribe line electrode despite the good improvement of expansion stress, and the structural strength at the first scribe line 11 being too low, making it prone to cracking and shortening its service life. Alternatively, the second scribe line 21 in the outer ring region 2 may be too shallow, resulting in an insignificant improvement effect on the stress problem.

[0050] Optionally, in the inner region 1, multiple first scribe lines 11 are sequentially arranged along the length of the scribe electrode. In the outer region 2, multiple second scribe lines 21 are sequentially arranged along the length of the scribe electrode. The distance between the intersection of two adjacent X-shaped structures along the length of the scribe electrode is S1, meaning the distance between the intersection of one X-shaped structure and the intersection of another adjacent X-shaped structure is S1. The distance between two adjacent second scribe lines 21 along the length of the scribe electrode is S2, satisfying: S2 / S1≥1.5. That is, the density of the second scribe lines 21 in the outer region 2 is less than the density of the first scribe lines 11 in the inner region 1, which better suits the actual needs of the inner region 1 having a higher curvature than the outer region 2, greater stress in the inner region 1, and greater difficulty in electrolyte reflux. If the ratio of the distance S2 between two adjacent second scribe lines 21 to the distance S1 between the intersections of two adjacent X-shaped structures is less than 1.5, then when the distance S2 between two adjacent second scribe lines 21 is appropriate, the distance S1 between the intersections of two adjacent X-shaped structures is too large. The stress absorption effect of the first scribe line 11 can be further improved, the stress in the inner ring region 1 will be uneven, and the stress in the area between two adjacent first scribe lines 11 will have nowhere to be released, which can easily lead to wrinkles and other phenomena. If the first scribe line 11 is deepened or widened to compensate for the poor effect, the structural strength at the first scribe line 11 will be too low, which can easily cause cracking and shorten the lifespan. When the distance S1 between the intersections of two adjacent X-shaped structures is appropriate, but the distance S2 between two adjacent second scribe lines 21 is too small, then the second scribe lines 21 in the outer ring region 2 will be too dense, which is not conducive to ensuring the capacity of the scribe line electrode.

[0051] Optionally, the distance S1 between the intersections of two adjacent X-shaped structures can range from 0.4mm to 4mm. If the distance S1 between the intersections of two adjacent X-shaped structures is greater than 4mm, the first scribe line 11 will be too sparse, and the stress absorption effect of the first scribe line 11 can be further improved. However, the stress in the inner ring region 1 will be uneven, and the stress in the area between two adjacent first scribe lines 11 will have nowhere to be released, which may easily lead to wrinkles and other phenomena. If the distance S1 between the intersections of two adjacent X-shaped structures is less than 0.4mm, the first scribe lines 11 will be too dense, which is not conducive to ensuring the capacity of the scribe line electrode.

[0052] Optionally, the distance S1 between the intersections of two adjacent X-shaped structures is 0.4 mm, 1 mm, 2 mm, 3 mm or 4 mm.

[0053] Optionally, the distance S2 between two adjacent second scribe lines 21 can range from 1mm to 10mm. If the distance S2 between two adjacent second scribe lines 21 is greater than 10mm, the second scribe lines 21 are too sparse, and the stress absorption effect of the second scribe lines 21 can be further improved. However, the stress in the outer ring region 2 is uneven, and the stress release in the area between two adjacent second scribe lines 21 is insufficient, which can easily lead to slight wrinkles. If the distance S2 between two adjacent second scribe lines 21 is less than 1mm, the second scribe lines 21 are too dense, which is not conducive to ensuring the capacity of the scribe line electrode.

[0054] Optionally, the distance S2 between two adjacent second markings 21 is 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm or 10mm.

[0055] Optionally, along the length of the etched electrode, the length of the inner ring region 1 is L1, and the total length of the etched electrode is L, satisfying: 0.3 ≥ L1 / L ≥ 0.15. This ratio of the inner ring region 1 allows the densely etched area to accurately cover the high-stress zone of the bare cell's inner ring. If the ratio of the dimension L1 of the inner ring region 1 along the length of the etched electrode to the total length L of the etched electrode is less than 0.15, some areas will still be high-expansion-stress areas, but without a denser set of first etched lines 11 to absorb stress, these areas will still experience a lower degree of electrolyte reflux stagnation and interfacial side reactions. If the ratio of the dimension L1 of the inner ring region 1 along the length of the etched electrode to the total length L of the etched electrode is greater than 0.3, dense first etched lines 11 will be set in areas with low stress, causing unnecessary capacity loss and compromising the structural strength of the bare cell.

[0056] Optionally, along the length of the etched electrode, the length of the outer ring region 2 is L2, and the total length of the etched electrode is L, satisfying: L2 / L≥0.3. This proportion of the outer ring region 2 allows the loosely etched area to accurately cover the low-stress zone of the bare cell's outer ring. If the ratio of the dimension L2 of the outer ring region 2 along the length of the etched electrode to the total length L of the etched electrode is less than 0.3, dense etched lines will be placed in areas with low stress, causing unnecessary capacity loss and compromising the structural strength of the bare cell.

[0057] Optionally, in this embodiment, the outer ring region 2 is connected to the inner ring region 1, that is, the dimension of the outer ring region 2 along the length direction of the etched electrode is L2=L-L1, i.e. 0.85≥L2 / L≥0.7, which can further enable the loosely etched outer ring region 2 to accurately cover the low stress zone of the bare cell outer ring, avoid unnecessary capacity loss, and maximize the structural strength of the bare cell.

[0058] Using the aforementioned etched electrode as the negative electrode, a 21700-type cylindrical lithium-ion battery was assembled, and its electrochemical performance was evaluated. The specific assembly process was as follows: after rolling, the electrode was slit, baked to remove moisture, and then etched. The etched electrode, along with the positive electrode and separator, was wound into a bare cell. Subsequently, casing, laser welding of the base, and welding of the cap were performed, followed by vacuum liquid injection and sealing. After liquid injection, the battery was placed in a dry environment and subjected to pre-charge film formation and formation processes. After formation, the battery was transferred to an aging chamber for high-temperature aging to stabilize the electrochemical interface and eliminate products with abnormal self-discharge. After aging, constant current discharge capacity testing was performed, and the batteries were sorted according to capacity and internal resistance to obtain qualified finished batteries. The rated capacity of this battery is 5000mAh (the positive electrode used was a conventional electrode without special treatment).

[0059] To verify whether the scribed electrode provided in this embodiment has stronger anti-expansion performance, whether it can reduce the electrolyte backflow resistance, reduce the polarization effect under high-rate charge and discharge, and suppress lithium plating on the negative electrode, this embodiment provides a series of experimental verification data. As shown in Table 1 below, this embodiment provides two sets of examples and eleven sets of comparative examples. A series of tests were conducted on the scribed electrode and battery of the two sets of examples and eleven sets of comparative examples. The test results are recorded in Table 2 below. The test methods are described below: (1) Test method for porosity of etched electrode sheet: The porosity of the negative electrode sheet is determined by gas displacement method, specifically by the following steps: The negative electrode sheet is immersed in ethyl methyl carbonate (EMC) for cleaning, and then measured by gas displacement method. The porosity of the negative electrode sheet is the percentage of the pore volume in the negative electrode sheet to the total volume of the negative electrode sheet. The calculation formula is: Porosity = (V-V0) / V×100%, where V0 is the true volume of the negative electrode sheet and V is the apparent volume of the negative electrode sheet.

[0060] (2) Test method for tensile strength of scribed electrode sheet: Cut rectangular specimens along the rolling direction from the uniformly coated scribed electrode sheet, with a width of 10-15 mm and a gauge length of 50-100 mm. Use a universal tensile testing machine equipped with toothed clamps to prevent slippage. Set the tensile speed to 5-50 mm / min, record the maximum load, and calculate the tensile strength according to σ=Fmax / (width×thickness). Test at least 3 valid specimens under each condition and take the average value. The relative humidity of the test environment is ≤50%, and the temperature is controlled at 23±2℃.

[0061] (3) The test method for 0-90% SOC fast charging time is as follows: Install a fresh cylindrical battery on the Arbin battery test cabinet fixture with a range of 30A, and connect the voltage and current lines and the temperature sampling line. Set the fast charging test program in a constant temperature environment, with a cutoff voltage range of 2.5V-4.2V. Charge the battery cell with a constant current and constant voltage of 2.5A, then discharge it at 1A and record the discharge capacity. Using 90% of the above discharge capacity value as the cutoff condition, perform a constant current charge of 15A. The 0-90% SOC fast charging time is the time taken for the above 15A fast charging step.

[0062] (4) Test method for capacity retention after 500 cycles: Install the battery on the Arbin battery test cabinet fixture with a range of 60A, and connect the voltage and current lines to the temperature sampling line. Set the cycle test program in a constant temperature environment, with a cutoff voltage range of 2.5V-4.2V, a charging current of 15A, a discharging current of 40A, and a rest time of 30min. Capacity retention after 500 cycles = Discharge capacity after the first cycle / Discharge capacity after the 500th cycle.

[0063] (5) Battery capacity test method: Install the battery on the Arbin battery test cabinet fixture and connect the voltage and current lines to the temperature sampling line. Set the capacity test program in a constant temperature environment, with a cutoff voltage range of 2.5V-4.2V. After discharging at 1A, perform a full charge at 2.5A constant current and constant voltage, and then discharge at 1A. Record the discharge capacity value after the full charge, which is the battery capacity.

[0064] Table 1 Table 2 Comparative Example 11 did not use the aforementioned etched electrode; instead, it used a conventional, unetched electrode. Comparing Examples 1 and 2 with Comparative Example 11, it can be seen that the porosity of the electrode increased significantly after etching, while the tensile strength showed no significant difference. Consequently, the fast charging and cycle performance were significantly improved.

[0065] The negative electrode in Comparative Example 1 uses a etched electrode, specifically, the inner region 1 has a first etched line 11 with an X-shaped structure, and the outer region 2 has parallel second etched lines 21. The angle α between any etched line 11 of the first etched line 11 in Comparative Example 1 and the width direction of the etched electrode is less than the minimum value of the aforementioned optimal range; that is, α is too small. Comparing Examples 1 and 2 with Comparative Example 1, it can be seen that when α is too small, the tensile strength of the etched electrode decreases, and the corresponding improvement effect over long cycles is limited.

[0066] In Comparative Example 2, the negative electrode uses a scribed electrode. The angle α between any scribe line of the X-shaped structure of the first scribe line 11 of the scribed electrode and the width direction of the electrode is greater than the maximum value of the aforementioned optimal range; that is, α is too large. Comparing Examples 1 and 2 with Comparative Example 1, it can be seen that when α is too large, the tensile strength of the scribed electrode decreases, and the corresponding long-cycle performance deteriorates. However, it is still better than Comparative Example 11, which does not have scribe lines.

[0067] Comparative Example 3 uses a scribed electrode. The line width K1 of any scribed line in the X-shaped structure of the scribed electrode in Comparative Example 3 is less than the minimum value of the aforementioned optimal range, i.e., K1 is too small. Testing showed that the negative electrode of Comparative Example 3 exhibited reduced electrolyte reflux capability and deteriorated fast charging and long-cycle performance, but it was still superior to Comparative Example 11, which did not have scribed lines.

[0068] Comparative Example 4 uses a etched electrode sheet for its negative electrode. The line width K1 of any etched line in the X-shaped structure of Comparative Example 4's etched electrode sheet is greater than the maximum value of the aforementioned optimal range, meaning K1 is too large. Testing of the negative electrode sheet of Comparative Example 4 revealed a significant decrease in tensile strength. Although short-term fast charging capability still improved, long-cycle performance deteriorated significantly, and the cell capacity decreased, but it was still superior to Comparative Example 11, which did not have etched lines. The low strength of the negative electrode sheet in Comparative Example 4 makes it prone to cracking or even breakage during cyclic charging and discharging, leading to a deterioration of the negative electrode interface.

[0069] Comparative Examples 5 and 8 show that when the first scribe line 11 or the second scribe line 21 is too shallow, it cannot withstand the impact caused by the volume expansion of the high silicon anode during charging. The return channel is prone to closure, and the fast charging and long cycle performance deteriorates, but it is still better than Comparative Example 11, which does not have scribe lines.

[0070] Comparative Example 6 shows that when the line width K2 of the parallel second scribe line 21 is too small, the electrolyte reflux capability is weakened, and the fast charging and long cycle performance deteriorates, but it is still better than Comparative Example 11, which does not have a scribe line.

[0071] Comparative Example 7 shows that when the line width K2 of the parallel second scribe line 21 is too large, the tensile strength of the electrode is significantly reduced. Although the short-term fast charging capability is still improved, the long-term cycle performance deteriorates and the cell capacity is reduced. However, the short-term fast charging capability and long-term cycle performance are still better than Comparative Example 11, which does not have scribe lines.

[0072] Comparative Example 9 uses a etched electrode for its negative electrode. The ratio of the depth D1 of any etched line in the X-shaped structure to the depth D2 of the second etched line 21 is less than the minimum value of the aforementioned optimal range, meaning D1 / D2 is too small. A D1 / D2 value of 1 means that the depths of the first etched line 11 and the second etched line 21 are the same. Testing shows that the tensile strength of the etched electrode is significantly reduced, long-cycle performance deteriorates, and the cell capacity is somewhat reduced. However, its short-term fast-charging capability and long-cycle performance are still superior to Comparative Example 11, which does not have etched lines.

[0073] Comparative Example 10 uses a etched electrode plate for its negative electrode. The ratio of the distance S2 between two adjacent second etched lines 21 to the distance S1 between the intersections of two adjacent X-shaped structures is less than the minimum value of the aforementioned optimal range, i.e., S1 / S2 is too small. With S1 / S2 set to 1, the density of the first etched line 11 in this comparative example is appropriate, while the density of the second etched line 21 is greater than the appropriate density. Testing shows that the tensile strength of the etched electrode plate is significantly reduced, resulting in superior short-term fast charging capability, but significantly deteriorating long-cycle performance and a significant decrease in cell capacity. However, its long-cycle performance is still superior to Comparative Example 11, which does not have etched lines.

[0074] This embodiment also provides a bare battery cell, including the aforementioned etched electrode. This bare battery cell can help improve the anti-expansion capability of the inner ring, reduce the backflow resistance of the electrolyte, reduce the polarization effect under high-rate charge and discharge, suppress lithium plating on the negative electrode, and improve the cycle stability and safety of the battery.

[0075] This embodiment also provides a battery, including a casing and the aforementioned bare cell, with the bare cell disposed within the casing. The bare cell of this battery exhibits higher resistance to expansion at its inner ring, reducing electrolyte backflow resistance, decreasing polarization effects under high-rate charge / discharge, suppressing lithium plating at the negative electrode, and improving the battery's cycle stability and safety.

[0076] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A scribed electrode sheet, characterized in that, The etched electrode has an active material layer (10) on at least one side along its thickness direction. The active material layer (10) contains a silicon-based active substance. The etched electrode has an inner ring region (1) at one end along its length direction. The etched electrode is used to wind and form a bare cell. The inner ring region (1) corresponds to the inner ring of the bare cell. The outer surface of the active material layer (10) in the inner ring region (1) has a first etch (11). The depth direction of the first etch (11) is parallel to the thickness direction of the etched electrode. The first etch (11) is an X-shaped structure. The angle α between any etch of the X-shaped structure and the width direction of the etched electrode is in the range of 7.5°-30°.

2. The etched electrode sheet according to claim 1, characterized in that, The line width K1 of any scribe line in the X-shaped structure satisfies: 5s × d 50 ≥K1≥0.5s×d 50 , where d 50 The average particle size of the silicon-based active material is given, and s% is the mass percentage of the silicon-based active material in the etched electrode.

3. The etched electrode sheet according to claim 1, characterized in that, The depth D1 of any scribe line in the X-shaped structure satisfies: D1 ≥ 2 × d 50 , where d 50 The average particle size of the silicon-based active material; And / or, the thickness of the etched electrode is D, and the depth D1 of any etched line of the X-shaped structure satisfies: 0.3≥D1 / D≥0.

1.

4. The etched electrode sheet according to claim 1, characterized in that, The intersection of the two etched lines of the X-shaped structure is located on the center line of the width direction of the etched electrode.

5. The etched electrode sheet according to any one of claims 1-4, characterized in that, The etched electrode also has an outer ring region (2), which is adjacent to the inner ring region (1). The outer ring region (2) is located on the outer ring of the bare cell. The outer surface of the active material layer (10) in the outer ring region (2) has a second etched line (21). The depth direction of the second etched line (21) is parallel to the thickness direction of the etched electrode. The second etched line (21) extends along the width direction of the etched electrode.

6. The etched electrode sheet according to claim 5, characterized in that, The line width K2 of the second scribe line (21) satisfies: 5s×d 50 ≥K2≥0.5s×d 50 , where d 50 The average particle size of the silicon-based active material is given, and s% is the mass percentage of the silicon-based active material in the etched electrode.

7. The etched electrode sheet according to claim 5, characterized in that, The depth D1 of any scribe line of the X-shaped structure and the depth D2 of the second scribe line (21) satisfy: 3≥D1 / D2≥1.5; And / or, the depth D2 of the second scribe line (21) satisfies: D2 ≥ 2 × d 50 , where d 50 The average particle size of the silicon-based active material; And / or, the thickness of the etched electrode is D, and the depth D2 of the second etched line (21) satisfies: 0.2≥D2 / D≥0.

05.

8. The etched electrode sheet according to claim 5, characterized in that, In the inner ring region (1), multiple first scribe lines (11) are arranged sequentially along the length direction of the scribe line electrode. In the outer ring region (2), multiple second scribe lines (21) are arranged sequentially along the length direction of the scribe line electrode. The distance between the intersection of two adjacent X-shaped structures along the length direction of the scribe line electrode is S1, and the distance between two adjacent second scribe lines (21) along the length direction of the scribe line electrode is S2, satisfying: S2 / S1≥1.5; And / or, along the length direction of the etched electrode, the length of the inner ring region (1) is L1, and the total length of the etched electrode is L, satisfying: 0.3≥L1 / L≥0.

15.

9. A bare battery cell, characterized in that, Including the etched electrode sheet as described in any one of claims 1-8.

10. A battery, characterized in that, It includes a housing and a bare battery cell as described in claim 9, wherein the bare battery cell is disposed within the housing.

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