A battery, a battery assembly and an electrical device

Abstract

This disclosure relates to a battery, battery assembly, and electrical device, including a positive electrode, a negative electrode, a positive electrode tab, and a negative electrode tab; the positive electrode includes a positive current collector and a positive electrode coating covering at least one surface of the positive current collector; along a first direction of the battery, the positive electrode coating includes a third positive electrode coating region, a second positive electrode coating region, and an optional first positive electrode coating region arranged sequentially; the negative electrode includes a negative electrode current collector and a negative electrode coating covering at least one surface of the negative electrode current collector, the negative electrode coating containing a negative electrode active material, the negative electrode active material including negative electrode active particles and an optional coating layer covering the surface of the negative electrode active particles; the negative electrode coating includes a third negative electrode coating region, a second negative electrode coating region, and an optional first negative electrode coating region arranged sequentially; the battery performance improvement factor Q ≤ 40; the battery performance balance factor P satisfies 100 < P ≤ 1000. The battery of this disclosure has both excellent fast charging performance and cycle life.

Description

Technical Field

[0001] This disclosure relates to the field of battery technology, and more specifically, to a battery, battery assembly, and electrical device. Background Technology

[0002] The main bottleneck in current battery technology lies in the fact that the current density and temperature rise in the regions near the tabs of both the positive and negative electrodes are higher than those further away, resulting in insufficient negative electrode capacity and a tendency for lithium plating, which limits the ability to further improve battery charging performance. Existing technologies improve the fast charging capability of the negative electrode by partitioning the negative electrode and increasing the orientation of graphite in certain regions near the tabs, thereby enabling rapid graphite insertion and extraction in these weaker areas. However, optimizing only the negative electrode side accelerates the electrochemical reaction rate in localized areas, leading to a sharp increase in heat generation near the tabs, widening the temperature difference within the cell, and reducing battery life, failing to achieve a balance between fast charging capability and lifespan. Summary of the Invention

[0003] The purpose of this disclosure is to provide a battery, battery pack, and electrical device that combines excellent fast charging performance and lifespan.

[0004] To achieve the above objectives, a first aspect of this disclosure provides a battery, the battery comprising a positive electrode sheet, a negative electrode sheet, a positive electrode tab, and a negative electrode tab, wherein the positive electrode sheet and the negative electrode sheet are stacked; the positive electrode sheet comprises a positive current collector and a positive electrode coating covering at least one surface of the positive current collector, the positive electrode coating comprising a positive electrode active material, the positive electrode active material comprising a first positive electrode active material, the first positive electrode active material being an olivine-type positive electrode material; along a first direction of the battery, the positive electrode coating comprises a third positive electrode coating region, a second positive electrode coating region, and an optional first positive electrode coating region arranged sequentially; a portion of the positive current collector corresponding to the third positive electrode coating region is connected to the positive electrode tab, and the mass ratio d of the first positive electrode active material in the third positive electrode coating region to the total mass ratio d2 of the first positive electrode active material in the second positive electrode coating region is greater than the mass ratio d2 of the first positive electrode active material in the second positive electrode coating region to the total mass ratio d2 of the first positive electrode active material in the second positive electrode coating region;

[0005] The negative electrode sheet includes a negative current collector and a negative electrode coating covering at least one surface of the negative current collector. The negative electrode coating contains a negative electrode active material, which includes negative electrode active particles and an optional coating layer covering the surface of the negative electrode active particles. Along a first direction of the battery, the negative electrode coating includes a third negative electrode coating region, a second negative electrode coating region, and an optional first negative electrode coating region arranged sequentially. The third negative electrode coating region corresponds to the third positive electrode coating region. The second negative electrode coating region corresponds to the second positive electrode coating region. The first negative electrode coating region corresponds to the first positive electrode coating region. The negative electrode coating includes a third negative electrode coating region and a second negative electrode coating region, and the portion of the negative current collector corresponding to the third negative electrode coating region is connected to the negative electrode tab. Alternatively, the negative electrode coating region includes a third negative electrode coating region, a second negative electrode coating region, and a first negative electrode coating region; the portion of the negative current collector corresponding to the first negative electrode coating region is connected to the negative electrode tab.

[0006] The performance improvement factor Q of the battery, as defined by equation (1), is ≤40; the performance balance factor P of the battery, as defined by equation (2), satisfies 100<P≤1000;

[0007] Q = g / r(1),

[0008] P = d / s(2);

[0009] Wherein, g is the ratio of the length of the positive electrode coating in the first direction to the length in the second direction, the first direction of the battery is a direction perpendicular to the side of the positive current collector containing the positive electrode tab and away from the positive electrode tab, the second direction is perpendicular to the first direction and perpendicular to the electrode thickness direction; r is the ratio of the length of the third positive electrode coating region to the length of the second positive electrode coating region in the first direction; d is the percentage of the mass of the first positive electrode active material in the third positive electrode coating region to the total mass of the positive electrode active material in the third positive electrode coating region; and s is the ratio of the coating thickness of the negative electrode active material in the third negative electrode coating region to the diameter of the negative electrode active particles.

[0010] Optionally, the positive electrode coating includes a third positive electrode coating region and a second positive electrode coating region arranged in sequence; the negative electrode coating region includes a third negative electrode coating region and a second negative electrode coating region arranged in sequence, and the portion of the negative electrode current collector corresponding to the third negative electrode coating region is connected to the negative electrode tab;

[0011] Q≤5;

[0012] The condition P satisfies 100 < P ≤ 1000.

[0013] Optionally, along the first direction of the battery, the second positive electrode coating region includes a plurality of sequentially arranged second positive electrode coating sub-regions, wherein the mass of the first positive electrode active material in any one of the second positive electrode coating sub-regions accounts for the proportion of the total mass of the positive electrode active material in the second positive electrode coating sub-region to d2', where d > d2'.

[0014] Optionally, r can be 0.05 to 5.

[0015] Optionally, g can be 1 to 15.

[0016] Optionally, the length of the positive electrode coating in the first direction is 200–1000 mm; and / or,

[0017] The length of the positive electrode coating in the second direction is 60-300 mm.

[0018] Optionally, d can be 20% to 100%.

[0019] Optionally, the mass percentage of the first positive electrode active material in the second positive electrode coating region to the total mass of the positive electrode active material in the second positive electrode coating region is d2, where d2 is 0–90%; and / or,

[0020] The value of 1000 > d / d2 > 1.

[0021] Optionally, s is 0.02-4%, preferably 0.1-0.3%.

[0022] Optionally, the ratio s2 of the coating thickness of the negative electrode active material in the second negative electrode coating region to the diameter of the negative electrode active particles is 0-2%, preferably 0-0.08%; and / or,

[0023] The value of 1000 > s / s² > 1.

[0024] Optionally, the positive electrode coating includes a third positive electrode coating region, a second positive electrode coating region, and a first positive electrode coating region arranged in sequence; the mass ratio d3 of the first positive electrode active material in the first positive electrode coating region to the total mass ratio d2 of the first positive electrode active material in the second positive electrode coating region is greater than the mass ratio d2 of the first positive electrode active material in the second positive electrode coating region; the negative electrode coating region includes a third negative electrode coating region, a second negative electrode coating region, and a first negative electrode coating region arranged in sequence, and the portion of the negative electrode current collector corresponding to the first negative electrode coating region is connected to the negative electrode tab;

[0025] Q≤40;

[0026] The condition P satisfies 100 < P ≤ 1000.

[0027] Optionally, Q is 1 ≤ Q ≤ 40.

[0028] Optionally, the performance improvement factor M of the battery as defined in equation (3) is ≤40; the performance balance factor N of the battery as defined in equation (4) satisfies 100<N≤1000;

[0029] M = g / k(3),

[0030] N = d³ / s³(4);

[0031] Wherein, g is the ratio of the length of the positive electrode coating in the first direction to the length in the second direction, the first direction of the battery is a direction perpendicular to the side of the positive current collector containing the positive electrode tab and away from the positive electrode tab, the second direction is perpendicular to the first direction and perpendicular to the electrode thickness direction; k is the ratio of the length of the first positive electrode coating area to the length of the second positive electrode coating area in the first direction; d3 is the proportion of the mass of the first positive electrode active material in the first positive electrode coating area to the total mass of the positive electrode active material in the first positive electrode coating area, and s3 is the ratio of the coating thickness of the negative electrode active material in the first negative electrode coating area to the diameter of the negative electrode active particles.

[0032] Optionally, the mass percentage of the first positive electrode active material in the first positive electrode coating region to the total mass of the positive electrode active material in the first positive electrode coating region is d3, where d3 is 20-100%; and / or,

[0033] d = d3.

[0034] Optionally, along the first direction of the battery, the second positive electrode coating region includes a plurality of sequentially arranged second positive electrode coating sub-regions, wherein the mass of the first positive electrode active material in any one of the second positive electrode coating sub-regions accounts for the proportion of the total mass of the positive electrode active material in the second positive electrode coating sub-region to d2', where d > d2' and d3 > d2'.

[0035] Optionally, the second positive electrode coating region includes three or more second positive electrode coating sub-regions, and the d2' of the second positive electrode sub-coating region decreases from both sides towards the middle.

[0036] Optionally, the ratio s3 of the coating thickness of the negative electrode active material in the first negative electrode coating region to the diameter of the negative electrode active particles is 0.02-4%, preferably 0.1-0.3%; and / or,

[0037] The value of s3 is the same as that of s.

[0038] Optionally, the olivine-type cathode material is lithium manganese iron phosphate material, which has Li... a Mn x Fe 1-xPO4 has the chemical formula shown in the figure, 0.9≤a≤1.5, 0≤x<1;

[0039] Optionally, the positive electrode coating further comprises a second positive electrode active material, the second positive electrode active material comprising a nickel-based cathode material, the nickel-based cathode material having Li b Ni 1-z-y Co z Mn y O2 has the chemical formula shown in the figure, where one or more of the following are true: 0.9≤b≤1.5, 0≤z<1, 0≤y<1.

[0040] Optionally, the average particle size of the negative electrode active material is 5–20 μm; the negative electrode active particles include graphite materials and / or carbon materials; the coating layer includes amorphous carbon, and the thickness of the coating layer is 10–400 nm.

[0041] Optionally, the ratio of the length of the negative electrode coating to the length of the positive electrode coating in the first direction is 1 to 1.05.

[0042] A second aspect of this disclosure provides a battery assembly including the battery described in the first aspect of this disclosure.

[0043] A third aspect of this disclosure provides an electrical device including the battery assembly described in the second aspect of this disclosure.

[0044] Through the above technical solution, this disclosure designs the battery performance improvement factor Q and performance balance factor P by simultaneously performing zoned control on the positive electrode and negative electrode, optimizes the distribution ratio of positive electrode active material in the positive electrode coating area and the coating effect of negative electrode graphite active material, and simultaneously improves the battery's fast charging capability and lifespan, so that the battery has both excellent fast charging performance and lifespan.

[0045] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0046] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0047] Figure 1 This is a schematic diagram of the positive and negative electrode synchronization partitioning in Embodiment 1 of this disclosure.

[0048] Figure 2 This is a schematic diagram of the partitioning of the positive electrode coating area in Embodiment 1 of this disclosure.

[0049] Figure 3 This is a schematic diagram of the partitioning of the negative electrode coating area in Embodiment 1 of this disclosure.

[0050] Figure 4 This is a schematic diagram of the battery in Embodiment 21 of this disclosure.

[0051] Figure 5 This is a schematic diagram of the positive and negative pole synchronization partitioning in Embodiment 21 of this disclosure.

[0052] Figure 6 This is a schematic diagram of the partitioning of the positive electrode coating area in Embodiment 21 of this disclosure.

[0053] Figure 7 This is a schematic diagram of the partitioning of the negative electrode coating area in Embodiment 21 of this disclosure. Detailed Implementation

[0054] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0055] This disclosure provides a battery, the battery including a positive electrode sheet, a negative electrode sheet, a positive electrode tab, and a negative electrode tab, wherein the positive electrode sheet and the negative electrode sheet are stacked; the positive electrode sheet includes a positive current collector and a positive electrode coating covering at least one surface of the positive current collector, the positive electrode coating including a positive electrode active material, the positive electrode active material including a first positive electrode active material, the first positive electrode active material being an olivine-type positive electrode material; along a first direction of the battery, the positive electrode coating includes a third positive electrode coating region, a second positive electrode coating region, and an optional first positive electrode coating region arranged sequentially; a portion of the positive current collector corresponding to the third positive electrode coating region is connected to the positive electrode tab, and the mass ratio d of the first positive electrode active material in the third positive electrode coating region to the total mass ratio d2 of the first positive electrode active material in the second positive electrode coating region is greater than the mass ratio d2 of the first positive electrode active material in the second positive electrode coating region to the total mass ratio d2 of the first positive electrode active material in the second positive electrode coating region;

[0056] The negative electrode sheet includes a negative current collector and a negative electrode coating covering at least one surface of the negative current collector. The negative electrode coating contains a negative electrode active material, which includes negative electrode active particles and an optional coating layer covering the surface of the negative electrode active particles. Along a first direction of the battery, the negative electrode coating includes a third negative electrode coating region, a second negative electrode coating region, and an optional first negative electrode coating region arranged sequentially. The third negative electrode coating region corresponds to the third positive electrode coating region. The second negative electrode coating region corresponds to the second positive electrode coating region. The first negative electrode coating region corresponds to the first positive electrode coating region. The negative electrode coating includes a third negative electrode coating region and a second negative electrode coating region, and the portion of the negative current collector corresponding to the third negative electrode coating region is connected to the negative electrode tab. Alternatively, the negative electrode coating region includes a third negative electrode coating region, a second negative electrode coating region, and a first negative electrode coating region; the portion of the negative current collector corresponding to the first negative electrode coating region is connected to the negative electrode tab.

[0057] The performance improvement factor Q of the battery, as defined by equation (1), is ≤40; the performance balance factor P of the battery, as defined by equation (2), satisfies 100<P≤1000;

[0058] Q = g / r(1),

[0059] P = d / s(2);

[0060] Wherein, g is the ratio of the length of the positive electrode coating in the first direction to the length in the second direction, the first direction of the battery is a direction perpendicular to the side of the positive current collector containing the positive electrode tab and away from the positive electrode tab, the second direction is perpendicular to the first direction and perpendicular to the electrode thickness direction; r is the ratio of the length of the third positive electrode coating region to the length of the second positive electrode coating region in the first direction; d is the percentage of the weight of the first positive electrode active material in the third positive electrode coating region to the total weight of the positive electrode active material in the third positive electrode coating region; and s is the ratio of the coating thickness of the negative electrode active material in the third negative electrode coating region to the diameter of the negative electrode active particles.

[0061] This disclosure improves the battery's performance by simultaneously controlling the positive and negative electrode plates in different zones, designing the battery's performance enhancement factor Q and performance balance factor P, optimizing the distribution ratio of positive active material in the positive electrode coating area and the coating effect of negative graphite active material, thereby simultaneously improving the battery's fast charging capability and lifespan, enabling the battery to have both excellent fast charging performance and lifespan.

[0062] In this disclosure, the first direction of the battery is a direction perpendicular to the side of the positive current collector containing the positive electrode tab and away from the positive electrode tab. The second direction of the battery is perpendicular to the first direction and perpendicular to the electrode thickness direction, for example... Figure 2As shown, the first direction of the battery refers to the direction along the y-axis, away from the positive electrode tab; the second direction of the battery refers to the direction along the x-axis. The ratio of the length of the third positive electrode coating area to the length of the second positive electrode coating area in the first direction refers to the ratio of the lengths of the third positive electrode coating area and the second positive electrode coating area in the first y-direction, for example... Figure 2 As shown, the ratio of the length of the third positive electrode coating region to that of the second positive electrode coating region in the first direction refers to L. CY3 :L CY2 The ratio of .

[0063] In this disclosure, the third negative electrode coating region corresponds to the third positive electrode coating region, the second negative electrode coating region corresponds to the second positive electrode coating region, and the first negative electrode coating region corresponds to the first positive electrode coating region. This means that the partition lines of the third and second negative electrode coating regions correspond to the partition lines of the third and second positive electrode coating regions, and vice versa. After these partition lines are aligned, the third negative electrode coating region corresponds to the third positive electrode coating region; the second negative electrode coating region corresponds to the second positive electrode coating region; and the first negative electrode coating region corresponds to the first positive electrode coating region.

[0064] In a preferred embodiment, the battery performance improvement factor is 0 < Q ≤ 40; for example, Q can be any value within the range of 0.1, 0.2, 0.3, 0.5, 1, 1.5, 2, 5, 10, 15, 20, 25, 30, 35, 37, 40, or any combination thereof. The above embodiments, by optimizing the aspect ratio of the electrode sheets and the length ratio of the third positive electrode coating region and the second positive electrode coating region, ensure that Q is within a suitable range, which is beneficial for simultaneously improving the battery's fast-charging capability and lifespan, enabling the battery to possess both excellent fast-charging performance and longevity.

[0065] For example, P can be any value within the range of 101, 105, 110, 120, 200, 300, 400, 500, 600, 700, 800, 900, 1000, or any two of these values. The above implementation method is beneficial for simultaneously improving the battery's fast-charging capability and lifespan, enabling the battery to possess both excellent fast-charging performance and longevity.

[0066] According to one embodiment of this disclosure, r is 0.05 to 5; for example, r can be any value within the range of 0.05, 0.1, 0.15, 0.25, 0.3, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, or any two of these. The above embodiment is beneficial for keeping the performance improvement factor Q within a suitable range, and for simultaneously improving the fast charging performance and lifespan of the battery.

[0067] According to one embodiment of this disclosure, g is 1 to 15; for example, g can be any value within the range of 1, 1.5, 2.5, 3.5, 5.5, 6, 6.5, 8, 10, 12, 13, 15, or any two of these. The above embodiment is beneficial for keeping the performance improvement factor Q within a suitable range, and for simultaneously improving the fast charging performance and lifespan of the battery.

[0068] According to one embodiment of this disclosure, the length of the positive electrode coating in the first direction can be 200-1000 mm. For example, the length of the positive electrode coating in the first direction can be any value within the range of 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 800, 900, 1000 mm, or any combination thereof; and / or, the length of the positive electrode coating in the second direction can be 60-300 mm, for example, any value within the range of 60, 80, 100, 120, 150, 200, 250, 300 mm, or any combination thereof. The above embodiments are beneficial for keeping the performance improvement factor Q within a suitable range, simultaneously improving the fast-charging performance and lifespan of the battery.

[0069] According to one embodiment of this disclosure, the length of the third positive electrode coating region in the first direction can be 10–500 mm, for example, any value within the range of 10, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, or any two of these values; and / or, the length of the second positive electrode coating region in the first direction can be 10–900 mm, for example, any value within the range of 10, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, or any two of these values. The above embodiments are beneficial for keeping the performance improvement factor Q within a suitable range, simultaneously improving the battery's fast-charging performance and lifespan.

[0070] According to one embodiment of this disclosure, d is 20% to 100%; for example, d can be any value within the range of 20, 25, 30, 35, 40, 50, 65, 80, 85, 90, 100, or any two of these. In this disclosure, d can be calculated using ICP testing to determine the percentage of the first positive electrode active material in the third positive electrode coating region by the total weight of the positive electrode active material in the third positive electrode coating region. The above embodiment is beneficial for balancing the distribution of active material in the positive electrode coating region, balancing the current distribution, avoiding excessive or insufficient active material causing excessive temperature difference in the cell, which would reduce battery life and safety performance, and ensuring that the performance balance factor P is within a suitable range, thus simultaneously improving the battery's fast charging performance and lifespan.

[0071] According to one embodiment of this disclosure, the weight ratio of the first positive electrode active material in the second positive electrode coating region to the total weight of the positive electrode active material in the second positive electrode coating region is d2, where d2 is 0-90%. For example, d2 can be any value within the range of 0, 10, 15, 25, 30, 35, 40, 50, 65, 80, 85, 90, or any combination thereof. d2 can be calculated using ICP testing to determine the percentage of the first positive electrode active material in the second positive electrode coating region relative to the total weight of the positive electrode active material in the second positive electrode coating region. This embodiment is beneficial for balancing the distribution of active material in the positive electrode coating region, balancing current distribution, and avoiding excessive or insufficient active material that could cause excessive temperature differences in the battery cell, leading to a decrease in battery life and safety performance. It also helps to keep the performance balance factor P within a suitable range, and is beneficial for simultaneously improving the battery's fast-charging performance and lifespan.

[0072] According to one embodiment of this disclosure, 1000 > d / d2 > 1. For example, the value of d / d2 can be any value within the range of 1.1, 1.5, 2, 3, 4, 5, 6, 8, 10, 50, 100, 200, 300, 400, 500, 700, 900, 999, or any combination thereof. This embodiment is beneficial for balancing the distribution of active material in the positive electrode coating region, balancing current distribution, and avoiding excessive or insufficient active material causing excessive temperature differences in the cell, which would reduce battery life and safety performance. It also helps to keep the performance balance factor P within a suitable range, and is beneficial for simultaneously improving the battery's fast-charging performance and lifespan.

[0073] In one embodiment, the positive electrode coating includes a third positive electrode coating region and a second positive electrode coating region arranged in sequence; the negative electrode coating region includes a third negative electrode coating region and a second negative electrode coating region arranged in sequence, and the portion of the negative electrode current collector corresponding to the third negative electrode coating region is connected to the negative electrode tab; Q ≤ 5; P satisfies 100 < P ≤ 1000. In the above embodiment, by simultaneously performing zoned control on the positive and negative electrode sheets, the performance improvement factor Q and performance balance factor P of the battery are further optimized, optimizing the distribution ratio of positive electrode active material and the coating effect of negative electrode graphite active material in the positive electrode coating region, simultaneously improving the battery's fast charging capability and lifespan, enabling the battery to possess both excellent fast charging performance and lifespan.

[0074] In a further embodiment, 0 < Q ≤ 5, for example, Q can be any value within the range of 0.1, 0.2, 0.3, 0.5, 1, 1.5, 2, 3, 4, 5, or any two of these. The above embodiments are beneficial for simultaneously improving the battery's fast-charging capability and lifespan, enabling the battery to possess both excellent fast-charging performance and longevity.

[0075] In the above embodiment, the positive and negative terminals of the battery are located at the same end of the battery. This results in superior fast-charging performance and longer battery life.

[0076] According to one embodiment of this disclosure, along a first direction of the battery, the second positive electrode coating region includes a plurality of sequentially arranged second positive electrode coating sub-regions. The mass ratio of the first positive electrode active material in any one of the second positive electrode coating sub-regions to the total mass of the positive electrode active material in the second positive electrode coating sub-region is d2', where d > d2'. This embodiment helps to balance the distribution of active material in the positive electrode coating region, balance the current distribution, and avoid excessive or insufficient active material causing excessive temperature differences in the cell, which could reduce battery life and safety performance. It also helps to simultaneously improve the battery's fast-charging performance and lifespan.

[0077] In another embodiment of this disclosure, the positive electrode coating includes a third positive electrode coating region, a second positive electrode coating region, and a first positive electrode coating region arranged in sequence; the mass ratio d3 of the first positive electrode active material in the first positive electrode coating region to the total mass of the positive electrode active material in the first positive electrode coating region is greater than the mass ratio d2 of the first positive electrode active material in the second positive electrode coating region to the total mass of the positive electrode active material in the second positive electrode coating region; the negative electrode coating region includes a third negative electrode coating region, a second negative electrode coating region, and a first negative electrode coating region arranged in sequence, and the portion of the negative electrode current collector corresponding to the first negative electrode coating region is connected to the negative electrode tab;

[0078] The condition Q ≤ 40; the condition P satisfies 100 < P ≤ 1000. In the above implementation, by simultaneously performing zoned control on the positive and negative electrode sheets, the performance improvement factor Q and performance balance factor P of the battery are further optimized. This optimizes the distribution ratio of positive electrode active material in the positive electrode coating area and the coating effect of negative electrode graphite active material, simultaneously improving the battery's fast-charging capability and lifespan, thus giving the battery both excellent fast-charging performance and lifespan.

[0079] In a further embodiment, 1 ≤ Q ≤ 40. For example, Q can be any value within the range of 1, 1.5, 2, 5, 10, 15, 20, 25, 30, 35, 37, 40, or any two of these values. The above embodiments are beneficial for simultaneously improving the battery's fast-charging capability and lifespan, enabling the battery to possess both excellent fast-charging performance and longevity.

[0080] In the above embodiment, the positive and negative terminals of the battery are located at opposite ends of the battery. This results in superior fast-charging performance and longer lifespan for the battery.

[0081] Furthermore, the percentage (d3) of the mass of the first positive electrode active material in the first positive electrode coating region relative to the total mass of the positive electrode active material in the first positive electrode coating region is greater than the percentage (d2) of the mass of the first positive electrode active material in the second positive electrode coating region relative to the total mass of the positive electrode active material in the second positive electrode coating region. By limiting d3 and d2, a balance between the battery's fast-charging performance and battery life can be further ensured.

[0082] Furthermore, in one embodiment of this application, the performance improvement factor M of the battery as defined by the following formula (3) is ≤40; the performance balance factor N of the battery as defined by the following formula (4) satisfies 100<N≤1000;

[0083] M = g / k(3),

[0084] N = d³ / s³(4);

[0085] Wherein, g is the ratio of the length of the positive electrode coating in the first direction to the length in the second direction, the first direction of the battery is a direction perpendicular to the side of the positive current collector containing the positive electrode tab and away from the positive electrode tab, the second direction is perpendicular to the first direction and perpendicular to the electrode thickness direction; k is the ratio of the length of the first positive electrode coating area to the length of the second positive electrode coating area in the first direction; d3 is the proportion of the mass of the first positive electrode active material in the first positive electrode coating area to the total mass of the positive electrode active material in the first positive electrode coating area, and s3 is the ratio of the coating thickness of the negative electrode active material in the first negative electrode coating area to the diameter of the negative electrode active particles.

[0086] This disclosure, by simultaneously performing zoned regulation on the positive and negative electrode sheets, designs the battery performance improvement factor M and performance balance factor N, which can further optimize the distribution ratio of positive electrode active material in the positive electrode coating area and the coating effect of negative electrode graphite active material, thereby simultaneously improving the battery's fast charging capability and lifespan, enabling the battery to have both excellent fast charging performance and lifespan.

[0087] In one embodiment, the battery performance improvement factor is 0 < M ≤ 40; for example, M can be any value within the range of 0.1, 0.2, 0.3, 0.5, 1, 1.5, 2, 5, 10, 15, 20, 25, 30, 35, 37, 40, or any two of these. The above embodiment, by optimizing the aspect ratio of the electrode and the length ratio of the first positive electrode coating region and the second positive electrode coating region, ensures that M is within a suitable range, which is beneficial for simultaneously improving the battery's fast-charging capability and lifespan, enabling the battery to possess both excellent fast-charging performance and lifespan.

[0088] For example, N can be any value within the range of 101, 105, 110, 120, 200, 300, 400, 500, 600, 700, 800, 900, 1000, or any combination thereof. The above implementation method is beneficial for simultaneously improving the battery's fast-charging capability and lifespan, enabling the battery to possess both excellent fast-charging performance and longevity.

[0089] According to one embodiment of this disclosure, k can be 0.05 to 5; for example, k can be any value within the range of 0.05, 0.1, 0.15, 0.25, 0.3, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, or any two of these. The above embodiment is beneficial for keeping the performance improvement factor M within a suitable range, and for simultaneously improving the battery's fast-charging performance and lifespan.

[0090] According to one embodiment of this disclosure, the weight percentage (d3) of the first positive electrode active material in the first positive electrode coating region relative to the total weight of the positive electrode active material in the first positive electrode coating region is 20% to 100%. For example, d3 can be any value within the range of 20, 25, 30, 35, 40, 50, 65, 80, 85, 90, 100, or any combination thereof. This embodiment is beneficial for balancing the distribution of active material in the positive electrode coating region, balancing current distribution, and avoiding excessive or insufficient active material that could cause excessive temperature differences in the battery cell, leading to a decrease in battery life and safety performance. It also helps to keep the performance balance factor within a suitable range, and is beneficial for simultaneously improving the battery's fast-charging performance and lifespan. d3 can be calculated using ICP testing to determine the percentage of the first positive electrode active material in the first positive electrode coating region relative to the total weight of the positive electrode active material in the first positive electrode coating region.

[0091] According to one embodiment of this disclosure, d = d3. The above embodiment is beneficial for balancing the distribution of active material in the positive electrode coating region, balancing current distribution, avoiding excessive or insufficient active material causing excessive temperature differences in the cell, which would reduce battery life and safety performance. It also helps to keep the performance balance factor within a suitable range, and is beneficial for simultaneously improving the battery's fast-charging performance and lifespan.

[0092] According to one embodiment of this disclosure, along a first direction of the battery, the second positive electrode coating region includes a plurality of sequentially arranged second positive electrode coating sub-regions. The mass ratio of the first positive electrode active material in any one of the second positive electrode coating sub-regions to the total mass of the positive electrode active material in the second positive electrode coating sub-region is d2', where d > d2' and d3 > d2'. In this embodiment, the partitioning of the second positive electrode coating sub-regions does not affect the values ​​of P and / or Q. The above embodiment is beneficial for balancing the distribution of active material in the positive electrode coating region, balancing current distribution, and avoiding excessive or insufficient active material causing excessive temperature differences in the cell, which would reduce battery life and safety performance. It also helps to simultaneously improve the battery's fast-charging performance and lifespan.

[0093] In one embodiment, the present disclosure does not specifically limit d2' of each second positive electrode coating sub-region, and it can be any value between 0% and 90%, for example, it can be any value within the range of 0, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or any combination of both. The d2' of each second positive electrode coating sub-region can be the same or different. The above embodiment is beneficial for balancing the distribution of active material in the positive electrode coating region, balancing current distribution, and avoiding excessive or insufficient active material causing excessive temperature differences in the cell, which would reduce battery life and safety performance. It is also beneficial for simultaneously improving the battery's fast-charging performance and lifespan.

[0094] In one embodiment, the second positive electrode coating region includes three or more second positive electrode coating sub-regions, and the d2' of the second positive electrode coating sub-regions decreases from both sides towards the middle. In this embodiment, the difference in d2' between two adjacent second positive electrode coating sub-regions can be the same or different. The above embodiment is beneficial for balancing the distribution of active material in the positive electrode coating region, balancing current distribution, and avoiding excessive or insufficient active material that could cause excessive temperature differences in the battery cell, leading to a decrease in battery life and safety performance. It is also beneficial for simultaneously improving the battery's fast charging performance and lifespan.

[0095] According to one embodiment of this disclosure, the olivine-type cathode material is lithium manganese iron phosphate. This embodiment is beneficial for simultaneously improving the battery's fast-charging performance and cycle life.

[0096] According to one embodiment of this disclosure, the lithium manganese iron phosphate material has Li a Mn x Fe 1-x The chemical composition of PO4 is as shown in the formula, where 0.9 ≤ a ≤ 1.5 and 0 ≤ x < 1. The above implementation method is beneficial for improving the cycle life of the battery.

[0097] According to one embodiment of this disclosure, the positive electrode coating further comprises a second positive electrode active material, the second positive electrode active material comprising a nickel-based layered positive electrode material; the nickel-based layered positive electrode material has Li b Ni 1-z-y Co z Mn y The chemical composition of O2, as shown in the formula, is 0.9≤b≤1.5, 0≤z<1, and 0≤y<1. The above implementation method is beneficial for improving the fast-charging performance of the battery.

[0098] According to one embodiment of this disclosure, each of the first, second, and third positive electrode coating regions independently includes one or more of a conductive agent, a binder, and a dispersant. This disclosure does not specifically limit the types of conductive agents, binders, and dispersants; they can be conventional types in the art. For example, conductive agents may include, but are not limited to, one or more of acetylene black, Super P, Super S, graphene, carbon fiber, carbon nanotubes, and Ketjen Black; binders may include, but are not limited to, one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polytetrafluoroethylene, polyacrylonitrile, polypropylene carbonate, styrene-butadiene rubber, nitrile rubber, sodium carboxymethyl cellulose, polyethylene oxide, and ethylene oxide-propylene oxide copolymer; dispersants may include, but are not limited to, one or more of carboxymethyl cellulose, polyacrylic acid, polymethyl methacrylate, and polyvinylpyrrolidone. This disclosure also does not specifically limit the mass ratio of the positive electrode active material to the conductive agent, binder, and dispersant in each positive electrode coating region; they can be conventional ratios in the art.

[0099] According to one embodiment of this disclosure, s is 0.02% to 4%. For example, s can be any value within the range of 0.02%, 0.05%, 0.07%, 0.08%, 0.1%, 0.2%, 0.3%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or any combination thereof, preferably 0.1% to 0.3%. In this disclosure, the measurement method for s may include: cutting the negative electrode sheet using Ar ion etching, taking images of the corresponding area using a scanning electron microscope or transmission electron microscope, and measuring the average ratio of the coating thickness of five particles in that area to the diameter of the negative electrode active particles. The above embodiment is beneficial for giving the negative electrode active material a suitable coating layer, which is beneficial for improving the fast-charging capability of the negative electrode and simultaneously improving the fast-charging capability and lifespan of the battery.

[0100] According to one embodiment of this disclosure, the ratio s2 of the coating thickness of the negative electrode active material to the diameter of the negative electrode active particles in the second negative electrode coating region is 0-2%. For example, s2 can be any value within the range of 0, 0.02%, 0.05%, 0.07%, 0.08%, 0.2%, 0.3%, 0.5%, 1%, 1.5%, 2%, or any combination thereof, preferably 0-0.08%. In this disclosure, the method for measuring s2 may include: cutting the negative electrode sheet using Ar ion etching, taking images of the corresponding area using a scanning electron microscope or transmission electron microscope, and then measuring the average ratio of the coating thickness of five particles in that area to the diameter of the negative electrode active particles. The above embodiment is beneficial for ensuring that the negative electrode active material has a suitable coating layer, which is beneficial for improving the fast-charging capability of the negative electrode and simultaneously improving the fast-charging capability and lifespan of the battery.

[0101] According to one embodiment of this disclosure, 1000 > s / s2 > 1. For example, the value of s / s2 can be any value within the range of 1.1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 8, 10, 50, 100, 150, 200, 300, 400, 500, 700, 900, 999, or any two of these. This embodiment is beneficial for providing a suitable coating layer for the negative electrode active material, improving the fast-charging capability of the negative electrode, and simultaneously enhancing the fast-charging capability and lifespan of the battery.

[0102] According to one embodiment of this disclosure, along a first direction of the battery, the second negative electrode coating region may include a plurality of second negative electrode coating sub-regions arranged sequentially. The ratio of the coating thickness of the negative electrode active material to the diameter of the negative electrode active particles in the second negative electrode coating sub-region is s2'. This disclosure does not specifically limit s2' for any one of the second negative electrode coating sub-regions; it may be the same or different, for example, it may be any value between 0 and 2%. The above embodiment is beneficial for giving the negative electrode active material a suitable coating layer, which is beneficial for improving the fast charging capability of the negative electrode and for simultaneously improving the fast charging capability and lifespan of the battery.

[0103] According to one embodiment of this disclosure, the ratio s3 of the coating thickness of the negative electrode active material to the diameter of the negative electrode active particles in the first negative electrode coating region is 0.02% to 4%. For example, s3 can be any value within the range of 0.02%, 0.05%, 0.07%, 0.08%, 0.1%, 0.2%, 0.3%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or any combination thereof, preferably 0.1% to 0.3%. In this disclosure, the measurement method for s3 may include: cutting the negative electrode sheet using Ar ion etching, taking images of the corresponding area using a scanning electron microscope or a transmission electron microscope, and measuring the average ratio of the coating thickness of five particles in that area to the diameter of the negative electrode active particles. The above embodiment is beneficial for ensuring the negative electrode active material has a suitable coating layer, which is beneficial for improving the fast-charging capability of the negative electrode and simultaneously improving the fast-charging capability and lifespan of the battery.

[0104] According to one embodiment of this disclosure, the value of s3 is the same as s. This embodiment is beneficial for ensuring the negative electrode active material has a suitable coating layer, for improving the fast-charging capability of the negative electrode, and for simultaneously improving the fast-charging capability and lifespan of the battery.

[0105] According to one embodiment of this disclosure, the negative electrode active particles comprise graphite material and / or carbon material; the graphite material and carbon material can be conventional types in the art, for example, the graphite material may include one or more of natural graphite, artificial graphite, and mesophase carbon microspheres, and the carbon material may include one or more of hard carbon, soft carbon, and carbon nanotubes; the coating layer comprises amorphous carbon. The above embodiment is beneficial for improving the fast-charging capability of the negative electrode, and for simultaneously improving the fast-charging capability and lifespan of the battery.

[0106] According to one embodiment of this disclosure, the preparation method of the negative electrode active material can be a conventional method in the art, and this disclosure does not make specific limitations. For example, it can be: mixing negative electrode active particles with an amorphous carbon precursor, and then carbonizing the mixed material.

[0107] According to one embodiment of this disclosure, the average particle size of the negative electrode active material is 5–20 μm. For example, the average particle size of the negative electrode active material can be any value within the range of 5, 8, 10, 12, 14, 16, 18, 20, or any two of these values. The thickness of the coating layer is 10–400 nm. For example, the thickness of the coating layer can be any value within the range of 10, 50, 100, 150, 200, 250, 300, 350, 400, or any two of these values. This disclosure does not specifically limit the preparation method of the negative electrode active material; any method conventional in the art can be used. The above embodiment is beneficial for improving the fast-charging capability of the battery.

[0108] According to one embodiment of this disclosure, each of the first, second, and third negative electrode coating regions independently includes one or more of a conductive agent, a binder, and a dispersant. This disclosure does not specifically limit the types of conductive agents, binders, and dispersants; they can be conventional types in the art. For example, conductive agents may include, but are not limited to, one or more of acetylene black, Super P, Super S, graphene, carbon fiber, carbon nanotubes, and Ketjen Black; binders may include, but are not limited to, one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polytetrafluoroethylene, polyacrylonitrile, polypropylene carbonate, styrene-butadiene rubber, nitrile rubber, sodium carboxymethyl cellulose, polyethylene oxide, and ethylene oxide-propylene oxide copolymer; dispersants may include, but are not limited to, one or more of carboxymethyl cellulose, polyacrylic acid, polymethyl methacrylate, and polyvinylpyrrolidone. This disclosure also does not specifically limit the mass ratio of the negative electrode active material to the conductive agent, binder, and dispersant in each negative electrode coating region; they can be conventional ratios in the art.

[0109] According to one embodiment of this disclosure, the length ratio of the negative electrode coating to the positive electrode coating in the first direction is 1 to 1.05; in this disclosure, the length ratio of the negative electrode coating to the positive electrode coating in the second direction can vary within a certain range, for example, it can be 1 to 1.05. The above embodiment further optimizes the aspect ratio of the negative electrode sheet and the positive electrode sheet, which is beneficial for simultaneously improving the battery's fast-charging capability and lifespan, enabling the battery to possess both excellent fast-charging performance and lifespan.

[0110] According to one embodiment of this disclosure, the length of the negative electrode coating in the first direction can be 200 to 1000 mm, for example, it can be any value in the range of 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 800, 900, 1000 or any two of these; the length of the negative electrode coating in the second direction can be 60 to 300 mm, for example, it can be any value in the range of 60, 80, 100, 120, 150, 200, 250, 300 or any two of these.

[0111] According to one embodiment of this disclosure, the battery includes one or more of prismatic and cylindrical batteries.

[0112] According to one embodiment of this disclosure, the positive electrode sheet and / or the negative electrode sheet can be square in shape. A square refers to a shape having a length direction and a width direction, such as a rectangle or a square.

[0113] A second aspect of this disclosure provides a battery assembly including the battery described in the first aspect of this disclosure.

[0114] A third aspect of this disclosure provides an electrical device including the battery described in the first aspect of this disclosure or the battery assembly described in the second aspect of this disclosure.

[0115] The electrical equipment disclosed herein can be any equipment that conventionally requires electricity, including but not limited to electric vehicles, energy storage cabinets, energy storage systems, computers, electric vehicles, air conditioners, refrigerators, washing machines, microwave ovens, printers, fax machines, etc.

[0116] The present disclosure will be described in detail below with reference to the embodiments, but this does not limit the present disclosure.

[0117] In this disclosure, the partitioning of the positive and negative electrode coatings can be performed using the following method:

[0118] The partitioning of the third positive electrode coating area and the second positive electrode coating area: After disassembling the positive and negative electrodes of the battery, along the first direction (y direction) of the positive electrode coating area of ​​the battery, sampling points with equal intervals (interval of 5 mm) are selected starting from the positive electrode tab side (using a circular sampler to cut a circle with a diameter of 16 mm as the sampling point). The mass percentage of Fe ions at different sampling points in the first direction is tested using ICP. The position of the sampling point where the mass percentage of Fe ions changes, perpendicular to the first direction of the battery, is the partitioning line between the third positive electrode coating area and the second positive electrode coating area.

[0119] The division between the first and second positive electrode coating areas can be achieved by selecting equally spaced sampling points (5mm apart) along the opposite direction of the first direction of the battery (the opposite direction of the y-direction), i.e., the direction closer to the positive electrode tab. These sampling points are measured using ICP to determine the mass percentage of Fe ions at different locations. The position perpendicular to the first direction of the battery where the Fe ion mass percentage changes is the dividing line between the first and second positive electrode coating areas. A change in the Fe ion mass percentage is defined as a difference of more than 10% between adjacent sampling points.

[0120] Method for measuring the length of the positive / negative electrode coating in the first and second directions: Using the positive / negative electrode coating as the measurement object, measure along the y and x directions of the coating with a ruler to obtain the length of the positive / negative electrode coating in the first and second directions.

[0121] Method for measuring the thickness of the positive / negative electrode coating area: The total thickness of the positive / negative electrode sheet is measured using a micrometer. The positive / negative electrode coating is wiped with alcohol. The thickness of the remaining foil after removing the positive / negative electrode coating is also measured using a micrometer. The thickness of the positive / negative electrode coating area is obtained by subtracting the thickness of the foil from the total thickness of the positive / negative electrode sheet.

[0122] The method for measuring the ratio s of the coating thickness of the negative electrode active material coating layer to the diameter of the negative electrode active particles (the measurement methods for s2 and s3 are the same as for s): The negative electrode sheet is cut using Ar ion etching. After taking images of the corresponding area using a scanning electron microscope or a transmission electron microscope, the average ratio of the coating thickness of 5 particles in the area to the diameter of the negative electrode active particles is measured.

[0123] The method for measuring the proportion d of the first positive electrode active material in the third positive electrode coating region to the total mass of the positive electrode active material in the third positive electrode coating region is as follows (the measurement methods for d2 and d3 are the same as for d):

[0124] After partitioning, the LMFP content in the third positive electrode coating area is equivalent to the Fe content ratio in that coating area. The average Fe ion mass percentage at the sampling points in the third positive electrode coating area is measured using ICP. The atomic percentage of Fe in LMFP is removed, and the mass percentage d of LMFP is calculated.

[0125] Example 1

[0126] like Figure 1 As shown, the battery of this embodiment 1 includes a positive electrode sheet, a negative electrode sheet, a positive electrode tab, and a negative electrode tab, wherein the positive electrode sheet and the negative electrode sheet are stacked; the positive electrode sheet includes a positive current collector and a positive electrode coating covering at least one surface of the positive current collector; along the first direction (y-direction) of the battery, i.e., away from the positive electrode tab, the positive electrode coating includes a third positive electrode coating region C3, a second positive electrode coating region C2, and a first positive electrode coating region C1 arranged in sequence; the negative electrode sheet includes a negative electrode current collector and a negative electrode coating covering at least one surface of the negative electrode current collector; along the first direction (y-direction) of the battery, the negative electrode coating region includes a third negative electrode coating region A3, a second negative electrode coating region A2, and a first negative electrode coating region A1 arranged in sequence; wherein the first negative electrode coating region A1 corresponds to the first positive electrode coating region C1, the second negative electrode coating region A2 corresponds to the second positive electrode coating region C2, and the third negative electrode coating region A3 corresponds to the third positive electrode coating region C3; as Figure 2 As shown, the length L of the positive electrode coating in the y direction CY The length L of the third positive electrode coating region in the first direction is 944 mm. CY3 The length L of the second positive electrode coating region in the first direction CY2 The length L of the first positive electrode coating region in the first direction CY1 The ratio is 1:3:1, L CY3 L CY2 L CY1 The lengths are 188.8 mm, 566.4 mm, and 188.8 mm, respectively; the length L of the positive electrode coating in the second x-direction. CX The thickness is 82.5 mm; the single-sided thickness H of the positive electrode coating is... C The thickness is 0.085 mm; the positive electrode coating includes a first positive electrode active material, lithium manganese iron phosphate (LMFP), and a second positive electrode active material, nickel-based layered positive electrode material. The chemical formula of lithium manganese iron phosphate (LMFP) is Li1Mn. 0.05 Fe 0.95 PO4, the chemical formula of nickel-based cathode material is Li1Ni 0.8 Co 0.1 Mn 0.1In the third positive electrode coating region, the weight of the first positive electrode active material accounts for 80% of the total weight of the positive electrode active material in the third positive electrode coating region (d). In the second positive electrode coating region, the weight of the first positive electrode active material LMFP accounts for 20% of the total weight of the positive electrode active material in the second positive electrode coating region (d2). The ratio of d to d2 is 4. In the first positive electrode coating region, the weight of the first positive electrode active material LMFP accounts for 80% of the total weight of the positive electrode active material in the first positive electrode coating region (d3). d = d3.

[0127] like Figure 3 As shown, the length L of the negative electrode coating region in the first direction y is... AY The length is 944 mm. The ratio of the length of the third negative electrode coating region in the first direction, the length of the second negative electrode coating region in the first direction, and the length of the first negative electrode coating region in the first direction is 1:3:1. AY3 L AY2 L AY1 The lengths are 188.8 mm, 566.4 mm, and 188.8 mm, respectively; the length L of the negative electrode coating in the x-direction is... AX The thickness is 82.5 mm; the single-sided thickness H of the negative electrode coating is... A The average particle size of the negative electrode active material is 0.085 mm. The negative electrode coating consists of graphite negative electrode active particles and an amorphous carbon layer coated on the graphite surface. The average particle size of the negative electrode active material is 15 μm, and the thickness of the carbon coating layer is 30 nm. In the third negative electrode coating region, the ratio s of the coating layer thickness to the diameter of the negative electrode active particles is 0.2%. In the second negative electrode coating region, the ratio s2 is 0.05%, and the ratio of s to s2 is 4. In the first negative electrode coating region, the ratio s3 is 0.2%, and s = s3. In Example 1, Q = 34.3, P = 400; M = 34.3, N = 400. Specific conditions are shown in Table 1.

[0128] The batteries used in Examples 2-20 and Comparative Examples 1-5 are the same as those in Example 1, with specific differences shown in Table 1.

[0129] Test Example 1

[0130] The fast charging performance and lifespan of the batteries from Examples 1-20 and Comparative Examples 1-5 were tested. The test results are shown in Table 1. The test methods are as follows:

[0131] Fast charging performance: 10-80% fast charging time test

[0132] The above embodiments and comparative examples were tested for 10-80% fast charging time. The test conditions were: ambient temperature (25℃±2℃), three-electrode battery was assembled, starting from 10% SOC, 5C was set as the initial charging rate, the potential of the reference electrode and the negative electrode tab were monitored simultaneously, when the negative electrode potential reached 0V, the current rate was reduced to 0.5C, and the battery was charged stepwise to 80% SOC to obtain the lithium plating boundary. The fast charging time from 10-80% SOC was obtained by integrating the lithium plating boundary (SOC-maximum current meter).

[0133] Lifespan Test: 500 Cycles of Fast Charging

[0134] The above embodiments and comparative examples were subjected to a 500-cycle fast charging life test. The test conditions were: ambient temperature (25℃±2℃). According to the above lithium plating boundary table, the maximum current value was taken every 5% SOC to obtain a stepped charging strategy. The fast charging cycle was performed for 500 cycles according to the strategy, and the ratio of the discharge capacity of 500 cycles to the discharge capacity of the first cycle was calculated to obtain the capacity retention rate after 500 cycles.

[0135] Table 1

[0136]

[0137] In Table 1, k and r are the same for Examples 1-20 and Comparative Examples 1-5. M and N can be directly calculated from the data in the table. Therefore, the values ​​of k, M and N are omitted in Table 1.

[0138] As can be seen from the data in Table 1, the battery disclosed herein has both excellent fast charging performance and cycle life.

[0139] By comparing Example 1 and Example 18, it can be seen that under the preferred conditions of d and d3 being the same and s and s3 being the same, the battery has better fast charging performance and better cycle life.

[0140] By comparing Example 1 and Example 19, it can be seen that within the preferred s / s2 ratio range of this disclosure, the battery has better fast charging performance and better cycle life.

[0141] Example 21

[0142] like Figure 4 and Figure 5As shown, the battery of this embodiment 21 includes a positive electrode sheet, a negative electrode sheet, a positive electrode tab, and a negative electrode tab, wherein the positive electrode sheet and the negative electrode sheet are stacked; the positive electrode sheet includes a positive current collector and a positive electrode coating covering at least one surface of the positive current collector; along the first direction (y-direction) of the battery, i.e., away from the positive electrode tab, the positive electrode coating includes a third positive electrode coating region C3 and a second positive electrode coating region C2 arranged in sequence; the negative electrode sheet includes a negative electrode current collector and a negative electrode coating covering at least one surface of the negative electrode current collector; along the first direction (y-direction) of the battery, the negative electrode coating region includes a third negative electrode coating region A3 and a second negative electrode coating region A2 arranged in sequence; wherein the third negative electrode coating region A3 corresponds to the third positive electrode coating region C3, and the second negative electrode coating region A2 corresponds to the second positive electrode coating region C2; as shown Figure 6 As shown, the length L of the positive electrode coating in the y direction CY The length L of the third positive electrode coating region in the first direction is 200mm. CY3 The length L of the second positive electrode coating area in the first direction is 35mm. CY2 The length L of the positive electrode coating in the second direction (x) is 165 mm. CX The thickness is 200mm; the single-sided thickness H of the positive electrode coating is... C The thickness is 0.085 mm; the positive electrode coating includes a first positive electrode active material, lithium manganese iron phosphate (LMFP), and a second positive electrode active material, nickel-based layered positive electrode material. The chemical formula of lithium manganese iron phosphate (LMFP) is Li1Mn. 0.05 Fe 0.95 PO4, the chemical formula of nickel-based cathode material is Li1Ni 0.8 Co 0.1 Mn 0.1 In the third positive electrode coating region, the weight of the first positive electrode active material accounts for 80% of the total weight of the positive electrode active material in the third positive electrode coating region, and the weight of the first positive electrode active material LMFP in the second positive electrode coating region accounts for 20% of the total weight of the positive electrode active material in the second positive electrode coating region. The ratio of d to d2 is 4.

[0143] like Figure 7 As shown, the length L of the negative electrode coating region in the first direction y is... AY The length L of the third negative electrode coating area in the first direction is 200mm. AY3 The length L of the second negative electrode coating area in the first direction is 35mm. AY2 The length L of the negative electrode coating in the x-direction is 165 mm. AX The thickness is 200mm; the single-sided thickness H of the negative electrode coating is... AThe average particle size is 0.085 mm. The negative electrode active material in the negative electrode coating includes negative electrode active graphite particles and an amorphous carbon layer coated on the graphite surface. The average particle size of the negative electrode active material is 15 μm, and the thickness of the carbon coating layer is 30 nm. In the third negative electrode coating region, the ratio s of the coating layer thickness to the diameter of the negative electrode active particles is 0.2%, and in the second negative electrode coating region, the ratio s2 of the coating layer thickness to the diameter of the negative electrode active particles is 0.05%. The ratio of s to s2 is 4. Specific conditions are shown in Table 2.

[0144] The batteries in Examples 22-25 and Comparative Examples 6-7 are the same as those in Example 21, with specific differences shown in Table 2.

[0145] Test Example 2

[0146] The fast charging performance and lifespan of the batteries from Examples 21-25 and Comparative Examples 6-7 were tested. The test results are shown in Table 2. The test methods are as follows:

[0147] Fast charging performance: 10-80% fast charging time test

[0148] The above embodiments and comparative examples were tested for 10-80% fast charging time. The test conditions were: ambient temperature (25℃±2℃), three-electrode battery was assembled, starting from 10% SOC, 5C was set as the initial charging rate, the potential of the reference electrode and the negative electrode tab were monitored simultaneously, when the negative electrode potential reached 0V, the current rate was reduced to 0.5C, and the battery was charged stepwise to 80% SOC to obtain the lithium plating boundary. The fast charging time from 10-80% SOC was obtained by integrating the lithium plating boundary (SOC-maximum current meter).

[0149] Lifespan Test: 500 Cycles of Fast Charging

[0150] The above embodiments and comparative examples were subjected to a 500-cycle fast charging life test. The test conditions were: ambient temperature (25℃±2℃). According to the above lithium plating boundary table, the maximum current value was taken every 5% SOC to obtain a stepped charging strategy. The fast charging cycle was performed for 500 cycles according to the strategy, and the ratio of the discharge capacity of 500 cycles to the discharge capacity of the first cycle was calculated to obtain the capacity retention rate after 500 cycles.

[0151] Table 2

[0152]

[0153] As can be seen from the data in Table 2, the battery disclosed herein has both excellent fast charging performance and cycle life.

[0154] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0155] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0156] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A battery, characterized in that, The battery includes a positive electrode plate, a negative electrode plate, a positive electrode tab, and a negative electrode tab, wherein the positive electrode plate and the negative electrode plate are stacked together; The positive electrode sheet includes a positive current collector and a positive electrode coating covering at least one surface of the positive current collector. The positive electrode coating contains a positive electrode active material, which includes a first positive electrode active material, and the first positive electrode active material is an olivine-type positive electrode material. Along a first direction of the battery, the positive electrode coating includes a third positive electrode coating region, a second positive electrode coating region, and a first positive electrode coating region arranged in sequence, or the positive electrode coating includes a third positive electrode coating region and a second positive electrode coating region arranged in sequence. The portion of the positive current collector corresponding to the third positive electrode coating region is connected to the positive electrode tab. The mass ratio d of the first positive electrode active material in the third positive electrode coating region to the total mass ratio d2 of the first positive electrode active material in the second positive electrode coating region is greater than the mass ratio d2 of the first positive electrode active material in the second positive electrode coating region to the total mass ratio d2 of the first positive electrode active material in the second positive electrode coating region. The negative electrode sheet includes a negative current collector and a negative electrode coating covering at least one surface of the negative current collector. The negative electrode coating contains a negative electrode active material, which includes negative electrode active particles and a coating layer covering the surface of the negative electrode active particles. Along a first direction of the battery, the negative electrode coating includes a third negative electrode coating region, a second negative electrode coating region, and a first negative electrode coating region arranged in sequence, or the negative electrode coating includes a third negative electrode coating region and a second negative electrode coating region arranged in sequence. The third negative electrode coating region corresponds to the third positive electrode coating region; the second negative electrode coating region corresponds to the second positive electrode coating region; the first negative electrode coating region corresponds to the first positive electrode coating region; the negative electrode coating includes a third negative electrode coating region and a second negative electrode coating region, and the portion of the negative current collector corresponding to the third negative electrode coating region is connected to the negative electrode tab; or, the negative electrode coating region includes a third negative electrode coating region, a second negative electrode coating region, and a first negative electrode coating region; the portion of the negative current collector corresponding to the first negative electrode coating region is connected to the negative electrode tab. The performance improvement factor Q of the battery, as defined by equation (1), is ≤40; the performance balance factor P of the battery, as defined by equation (2), satisfies 100<P≤1000; Q=g / r(1) P=d / s(2) Wherein, g is the ratio of the length of the positive electrode coating in the first direction to the length in the second direction, the first direction of the battery is a direction perpendicular to the side of the positive current collector containing the positive electrode tab and away from the positive electrode tab, the second direction is perpendicular to the first direction and perpendicular to the electrode thickness direction; r is the ratio of the length of the third positive electrode coating region to the length of the second positive electrode coating region in the first direction; d is the percentage of the mass of the first positive electrode active material in the third positive electrode coating region to the total mass of the positive electrode active material in the third positive electrode coating region; and s is the ratio of the coating thickness of the negative electrode active material in the third negative electrode coating region to the diameter of the negative electrode active particles.

2. The battery according to claim 1, wherein, The positive electrode coating includes a third positive electrode coating region and a second positive electrode coating region arranged in sequence; the negative electrode coating region includes a third negative electrode coating region and a second negative electrode coating region arranged in sequence, and the portion of the negative electrode current collector corresponding to the third negative electrode coating region is connected to the negative electrode tab; Q≤5; The condition P satisfies 100 < P ≤ 1000.

3. The battery according to claim 2, wherein, Along the first direction of the battery, the second positive electrode coating region includes a plurality of second positive electrode coating sub-regions arranged in sequence, wherein the mass of the first positive electrode active material in any one of the second positive electrode coating sub-regions accounts for the proportion of the total mass of the positive electrode active material in the second positive electrode coating sub-region to d2', where d > d2'.

4. The battery according to claim 1, wherein, r ranges from 0.05 to 5.

5. The battery according to claim 1, wherein, g ranges from 1 to 15.

6. The battery according to claim 5, wherein, The length of the positive electrode coating in the first direction is 200~1000 mm; and / or, The length of the positive electrode coating in the second direction is 60~300mm.

7. The battery according to claim 1, wherein, d ranges from 20% to 100%.

8. The battery according to claim 1, wherein, The mass percentage of the first positive electrode active material in the second positive electrode coating region to the total mass of the positive electrode active material in the second positive electrode coating region is d2, where d2 is 0~90%; and / or, The value of 1000 > d / d2 > 1.

9. The battery according to claim 1, wherein, s ranges from 0.02% to 4%.

10. The battery according to claim 9, wherein, s is 0.1~0.3%.

11. The battery according to claim 1, wherein, In the second negative electrode coating region, the ratio s2 of the coating thickness of the negative electrode active material to the diameter of the negative electrode active particles is 0~2%; and / or, The value of 1000 > s / s² > 1.

12. The battery according to claim 11, wherein, s2 is 0~0.08%.

13. The battery according to claim 1, wherein, The positive electrode coating includes a third positive electrode coating region, a second positive electrode coating region, and a first positive electrode coating region arranged in sequence; the mass ratio d3 of the first positive electrode active material in the first positive electrode coating region to the total mass of the positive electrode active material in the first positive electrode coating region is greater than the mass ratio d2 of the first positive electrode active material in the second positive electrode coating region; the negative electrode coating region includes a third negative electrode coating region, a second negative electrode coating region, and a first negative electrode coating region arranged in sequence, and the portion of the negative electrode current collector corresponding to the first negative electrode coating region is connected to the negative electrode tab; Q≤40; The condition P satisfies 100 < P ≤ 1000.

14. The battery according to claim 13, wherein, The value of Q is 1 ≤ Q ≤ 40.

15. The battery according to claim 13, wherein, The performance improvement factor M of the battery as defined in equation (3) is ≤40; the performance balance factor N of the battery as defined in equation (4) satisfies 100<N≤1000; M=g / k(3) N=d3 / s3(4; Wherein, g is the ratio of the length of the positive electrode coating in the first direction to the length in the second direction, the first direction of the battery is a direction perpendicular to the side of the positive current collector containing the positive electrode tab and away from the positive electrode tab, the second direction is perpendicular to the first direction and perpendicular to the electrode thickness direction; k is the ratio of the length of the first positive electrode coating area to the length of the second positive electrode coating area in the first direction; d3 is the proportion of the mass of the first positive electrode active material in the first positive electrode coating area to the total mass of the positive electrode active material in the first positive electrode coating area, and s3 is the ratio of the coating thickness of the negative electrode active material in the first negative electrode coating area to the diameter of the negative electrode active particles.

16. The battery according to any one of claims 13-15, wherein, The mass percentage of the first positive electrode active material in the first positive electrode coating region to the total mass of the positive electrode active material in the first positive electrode coating region is d3, where d3 is 20-100%; and / or, d=d3.

17. The battery according to any one of claims 13-15, wherein, Along the first direction of the battery, the second positive electrode coating region includes a plurality of second positive electrode coating sub-regions arranged in sequence. The mass of the first positive electrode active material in any one of the second positive electrode coating sub-regions accounts for the proportion of the total mass of the positive electrode active material in the second positive electrode coating sub-region to d2', where d > d2' and d3 > d2'.

18. The battery according to claim 17, wherein, The second positive electrode coating region includes more than three second positive electrode coating sub-regions, and the d2' of the second positive electrode sub-coating region decreases from both sides towards the middle.

19. The battery according to any one of claims 13-15, wherein, The ratio s3 of the coating thickness of the negative electrode active material to the diameter of the negative electrode active particles in the first negative electrode coating region is 0.02~4%; and / or, The value of s3 is the same as that of s.

20. The battery according to claim 19, wherein, s3 is 0.1% to 0.3%.

21. The battery according to claim 1, wherein, The olivine-type cathode material is lithium manganese iron phosphate material, which has Li... a Mn x Fe 1-x PO4 has the chemical formula shown in the formula, 0.9≤a≤1.5, 0≤x<1.

22. The battery according to claim 1, wherein, The positive electrode coating further comprises a second positive electrode active material, the second positive electrode active material comprising a nickel-based cathode material, the nickel-based cathode material having Li b Ni 1-z-y Co z Mn y O2 has the chemical formula shown in the figure, where one or more of the following are true: 0.9≤b≤1.5, 0≤z<1, 0≤y<1.

23. The battery according to claim 1, wherein, The average particle size of the negative electrode active material is 5~20μm; the negative electrode active particles include graphite materials and / or carbon materials; the coating layer includes amorphous carbon, and the thickness of the coating layer is 10~400nm.

24. The battery according to claim 1, wherein, The ratio of the length of the negative electrode coating to the length of the positive electrode coating in the first direction is 1 to 1.

05.

25. A battery assembly, characterized in that, Includes the battery described in any one of claims 1 to 24.

26. An electrical appliance, characterized in that, Includes the battery as described in any one of claims 1 to 24 or the battery assembly as described in claim 25.

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