Battery and battery device

Abstract

The utility model relates to the technical field of batteries, and discloses a battery and a battery device. The battery comprises a first pole piece, the first pole piece comprises a first tab, a first active material region and a second active material region, and the second active material region and the first active material region are sequentially arranged in the leading-out direction of the first tab. The first active material region includes a first active material, the second active material region includes a second active material, and the Li + diffusion coefficient of the first active material is greater than the Li + diffusion coefficient of the second active material. According to the first pole piece, the Li < + > diffusion coefficient of the first active substance is larger than that of the second active substance, so that the diffusion speed of Li < + > in the active substances can be matched with the current density in a corresponding region in the charging and discharging process, and the charging and discharging speed of the battery and the output power of an external circuit are improved; and lithium precipitation is also reduced.

Description

Technical Field

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

[0002] In recent years, the application range of lithium-ion batteries has become increasingly wide. For example, lithium-ion batteries can be used in energy storage fields such as hydropower, wind power, and solar power plants; they can also be used in transportation vehicles such as electric bicycles, electric motorcycles, and electric cars; and they can be used in defense technology fields such as military equipment and aerospace. A lithium-ion battery consists of electrodes, which include current collectors and active materials. The composition of the active material and its distribution on the surface of the current collector have a significant impact on the performance of the lithium-ion battery. Optimizing the composition and distribution of the active material has become crucial for improving the performance of lithium-ion batteries. Utility Model Content

[0003] This invention provides a battery and a battery device, wherein the battery includes electrodes that improve battery performance by setting multiple active materials and optimizing the distribution of these active materials on the surface of the current collector.

[0004] In a first aspect, embodiments of the present invention provide a battery. The battery includes a casing and a first electrode, the first electrode being located inside the casing;

[0005] The first electrode includes a first tab, a first active material region, and a second active material region. Along the lead-out direction of the first tab, the second active material region and the first active material region are arranged sequentially. The first active material region includes a first active material, and the second active material region includes a second active material. The first active material has a Li content... + The diffusion coefficient is DLi + 1, the Li of the second active substance + The diffusion coefficient is DLi + 2, the DLi + 1 and the DLi + 2. Satisfies the following relationship: DLi + 1>DLi + 2.

[0006] The beneficial effects of the battery provided in this embodiment of the present invention are as follows:

[0007] The first electrode of the aforementioned battery includes a first active material region and a second active material region, wherein the first active material region is adjacent to the first tab, and the second active material region is located on the side of the first active material region away from the first tab. During the charging and discharging process of the aforementioned battery, because the first active material region is closer to the first tab, the current density of the first active material region is greater than the current density of the second active material region.

[0008] The first electrode also includes a first active material and a second active material, wherein the Li of the first active material is... + Li has a diffusion coefficient greater than that of the second active material + Diffusion coefficient. That is, the Li of the first active substance. + The diffusion ability is relatively strong, and the Li of the second active material is also relatively strong. + The diffusion ability is relatively weak. In specific distribution, the first active material is distributed in the region with higher current density, while the second active material is distributed in the region with lower current density. This is due to the Li... + Li has strong diffusion ability; therefore, within the first active material region, Li... + The diffusion rate of the second active material can match the higher current density, thereby improving the battery's charge and discharge rate and the output power of the external circuit. However, if the second active material is distributed in the region of the first active material with a higher current density, the Li₂ of the second active material will... + Its poor diffusion ability easily leads to a mismatch between ion and electron transport, thus initiating lithium plating. Therefore, Li... + The second active material, which has weaker diffusion ability, is distributed in the second active material region far away from the first electrode, which can make the transport of ions and electrons more matched, thereby reducing the risk of lithium plating.

[0009] Secondly, embodiments of the present invention also provide a battery device. The battery device includes a housing and batteries as described in any of the first aspects above, with a plurality of the batteries located within the housing.

[0010] The beneficial effects of the battery device provided in this embodiment of the present invention are as follows:

[0011] In the aforementioned battery device, the battery includes a first electrode, which comprises a first active material and a second active material. The first and second active materials are not mixed but are arranged in different regions. Taking the first tab as a reference, the first active material is arranged in the region closer to the first tab, and the second active material is arranged in the region farther from the first tab. The current density in the first active material region is greater than the current density in the second active material region. This is because the Li of the first active material... + Li has strong diffusion ability; therefore, within the first active material region, Li...+ The diffusion rate of Li can be matched with a larger current density, thereby improving the battery's charge and discharge rate and the output power of the external circuit. In the second active material region, Li... + The diffusion rate can also be matched with the current density in the region, thereby reducing the risk of lithium plating. Attached Figure Description

[0012] Figure 1 This is an internal schematic diagram of a battery provided in an embodiment of this application;

[0013] Figure 2 This is a schematic diagram of the structure of the first electrode provided in an embodiment of this application;

[0014] Figure 3 for Figure 2 The first electrode is shown in cross-sectional view AA.

[0015] Figure 4 Another structural schematic diagram of the first electrode provided in the embodiments of this application;

[0016] Figure 5 A schematic diagram showing the connection between the first reference electrode, the second reference electrode, and the third reference electrode and the first electrode sheet, respectively, provided for embodiments of this application;

[0017] Figure 6 This is a schematic diagram of the structure of the second pole piece provided in an embodiment of this application;

[0018] Figure 7 This is a schematic diagram showing the distribution of active materials contained in the second electrode sheet provided in an embodiment of this application.

[0019] Figure 8 This is a schematic diagram showing the arrangement of the first and second electrodes provided in an embodiment of this application;

[0020] Figure 9 A schematic diagram illustrating another arrangement of the first and second electrodes provided in an embodiment of this application;

[0021] Figure 10 This is a schematic diagram of a battery device provided in an embodiment of this application.

[0022] Figure label:

[0023] 1-Battery; 2-Casing;

[0024] 10-Shell; 11-Shell body;

[0025] 12-Cover plate assembly; 121-Pole post;

[0026] 20 - First electrode; 21 - First current collector;

[0027] 211 - First surface; 212 - Second surface;

[0028] 22 - First active substance; 23 - Second active substance;

[0029] 201 - First tab; 202 - First active material region;

[0030] 203 - Second active material region; 30 - First reference electrode;

[0031] 40 - Second reference electrode; 50 - Third reference electrode;

[0032] 60 - Second electrode; 61 - Second current collector;

[0033] 62-Third active substance; 63-Fourth active substance;

[0034] 601 - Second tab; 602 - Third active material region;

[0035] 603 - Fourth active substance region. Detailed Implementation

[0036] The technical solutions in the exemplary embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The exemplary embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of this application. Therefore, it should be understood that various modifications and changes can be made to the exemplary embodiments without departing from the scope of protection of this application.

[0037] In the description of this application, unless otherwise expressly specified and limited, the terms “first” and “second” are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term “multiple” refers to two or more; and the term “and / or” includes any and all combinations of one or more of the associated listed items. In particular, references to “the / described” object or “an” object are also intended to indicate one of a possible plurality of such objects.

[0038] Unless otherwise specified or explained, the terms "connect," "fixed," etc. should be understood broadly. For example, "connected" can mean a fixed connection, a detachable connection, an integral connection, an electrical connection, or a signal connection; "connected" can mean a direct connection or an indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0039] Furthermore, it should be understood that the directional terms such as "upper," "lower," "inner," and "outer" described in the exemplary embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the exemplary embodiments of this application. It should also be understood that, in the context of an element or feature being connected to another element(s) "upper," "lower," "inner," or "outer," it can be directly connected to the other element(s) "upper," "lower," "inner," or "outer," or indirectly connected to the other element(s) "upper," "lower," "inner," or "outer" through an intermediate element.

[0040] Figure 1 This is a schematic diagram of the structure of a battery provided in an embodiment of this application, such as... Figure 1 As shown, in one embodiment, the battery 1 includes a housing 10 and a first electrode 20. The first electrode 20 is located inside the housing 10 and can be either a positive electrode or a negative electrode.

[0041] Figure 2 This is a schematic diagram of the structure of the first electrode provided in an embodiment of this application, as shown below. Figure 2 As shown, in one embodiment, the first electrode 20 includes a first current collector 21, a first active material 22, and a second active material 23. The first current collector 21 functions to collect current and carry the first active material 22 and the second active material 23. The first current collector 21 can be a copper foil or an aluminum foil. The first active material 22 and the second active material 23 can be embedded with Li. + Or detach from Li + .

[0042] Li + The process of embedding and extracting in electrode materials can be understood as Li + The diffusion process of Li. + The diffusion capacity of an electrode material can be represented by the diffusion coefficient D. Specifically, the larger the value of D, the greater the diffusion capacity of Li. + The stronger the diffusion ability of Li in the electrode material, or in other words, the better. + The faster the diffusion rate in the electrode material, the better. Conversely, the smaller the value of D, the faster the diffusion rate of Li. + The weaker the diffusion ability of Li in the electrode material, or in other words, the lower the diffusion ability of Li. + The slower the diffusion rate in the electrode material.

[0043] In the first electrode 20, the Li of the first active material 22 + Diffusion coefficient and Li of the second active material 23 + The diffusion coefficients are different. If we take DLi... + 1 represents Li of the first active substance 22 +Diffusion coefficient, in terms of DLi + 2 represents Li of the second active substance 23 + The diffusion coefficient, then DLi + 1>DLi + 2. In other words, Li + The diffusion rate in the first active material 22 is greater than that in Li + The diffusion rate in the second active substance 23.

[0044] Figure 3 This is a schematic diagram showing the distribution of the active material contained in the first electrode sheet provided in an embodiment of this application, such as... Figure 3 As shown, based on the distribution of the active material, the first electrode 20 includes a first tab 201, a first active material region 202, and a second active material region 203. In the specific configuration of the first tab 201, the first tab 201 can be the portion of the first current collector 21 not covered by the active material. Alternatively, the first tab 201 can also be a separate conductive structure. During charging and discharging, the first tab 201 of the battery 1 can be electrically connected to an external power source or electrical device.

[0045] like Figure 1 As shown, in one embodiment, the housing 10 includes a housing body 11 and a cover assembly 12. The housing body 11 has an opening, and the cover assembly 12 covers the opening. A first electrode 20 is located inside the housing body 11, and the first electrode tab 201 of the first electrode 20 can be electrically connected to the housing body 11. The housing body 11 serves as an output electrode and is electrically connected to an external power source or electrical device. Alternatively, the first electrode tab 201 of the first electrode 20 can also be electrically connected to a terminal post 121 in the cover assembly 12. The terminal post 121 serves as an output electrode and is electrically connected to an external power source or electrical device. Optionally, the first electrode tab 201 can be directly electrically connected to the terminal post 121, or it can be electrically connected to the terminal post 121 via an adapter.

[0046] When specifically configuring the first active material region 202 and the second active material region 203, the second active material region 203 and the first active material region 202 are arranged sequentially along the lead-out direction of the first tab 201. If the lead-out direction of the first tab 201 is denoted as the first direction X1, then the second active material region 203, the first active material region 202, and the first tab 201 are arranged sequentially along the aforementioned first direction X1. Specifically, the first active material region 202 and the first tab 201 are adjacent, and the second active material region 203 is located on the side of the first active material region 202 furthest from the first tab 201. During charging and discharging, because the first active material region 202 is closer to the first tab 201, the current density of the first active material region 202 is greater than the current density of the second active material region 203.

[0047] The first active material region 202 and the second active material region 203 are positioned differently relative to the first tab 201, and the active materials distributed in the first active material region 202 and the second active material region 203 are also different. Specifically, the first active material region 202 contains the first active material 22, and the second active material region 203 contains the second active material 23. Because the Li of the first active material 22... + Li has strong diffusion ability; therefore, within the first active material region 202, Li + The diffusion rate can match the large current density in this region, thereby improving the battery's charge and discharge rate and the output power of the external circuit. Furthermore, if the second active material 23 is distributed in the first active material region 202, then due to the Li of the second active material 23... + Li has poor diffusion ability. + The diffusion rate of Li is relatively low. + The inability to quickly reach the active material at the other electrode causes Li to... + The Li deposited on the surface of this electrode is equivalent to this portion of Li. + It is impossible to return to the first electrode 20, meaning that this part of Li... + The usable capacity is reduced, and battery capacity decays. Furthermore, lithium plating can cause lithium dendrites to pierce the separator, resulting in a short circuit between the positive and negative electrodes. Therefore, Li... + The second active material 23, which has weak diffusion ability, is distributed in the second active material region 203 far away from the first electrode 201, which can make the transport of ions and electrons more matched, thereby reducing the risk of lithium plating.

[0048] Furthermore, compared to electrodes containing only one active material, this application adds another Li... + The use of active materials with a high diffusion coefficient, and their distribution in the region near the electrode tabs, improves the battery's charge and discharge rate and the output power of the external circuitry, thereby enhancing battery performance and making the battery more adaptable to the demands of fast charging.

[0049] In one specific embodiment, DLi + 1 and DLi + 2 satisfies the following relationship: 1.0 < DLi + 1 / DLi + 2 ≤ 2.0. Optional, DLi + 1 / DLi + The value of 2 can be 1.2, 1.4, 1.6, 1.8 or other values ​​that meet the above range, which will not be listed one by one in this application.

[0050] Regarding the first active substance 22 and the second active substance 23, both except for Li +Besides the differences in diffusion coefficients, there are other differences as well. For example, the upper limit voltage of the first active material 22 and the upper limit voltage of the second active material 23 are different. In one embodiment, the upper limit voltage of the first active material 22 is V1, and the upper limit voltage of the second active material 23 is V2, where V1 > V2. This is because the first active material 22 is distributed in the first active material region 202, which is closer to the first electrode 201, and the current density in the first active material region 202 is relatively large. Therefore, by making the upper limit voltage of the first active material 22 greater than that of the second active material 23, the high voltage resistance of the first active material 22 can be improved, thereby meeting the requirements of fast charging and alleviating the lithium plating phenomenon during fast charging.

[0051] In one specific embodiment, the potential range of the first active substance 22 is [V1, V2], where V2 is the lower limit voltage of the first active substance 22, V2 < V1, and ΔV1 = V1 - V2. The potential range of the second active substance 23 is [V1', V2'], where V2' is the lower limit voltage of the second active substance 23, V2' < V1', and ΔV2 = V1' - V2'. Compared to ΔV1, ΔV2 is smaller than ΔV1. That is, the potential range of the first active substance 22 is wider than that of the second active substance 23.

[0052] Regarding the first active material region 202 and the second active material region 203, besides differing in their distance from the first electrode 201, their areas can also differ. For example... Figure 3 As shown, in one embodiment, the area of ​​the first active material region 202 is larger than the area of ​​the second active material region 203. In this embodiment, by increasing the proportion of the first active material region 202, the content of the first active material 22 is correspondingly increased, further improving the charge and discharge rate of the battery 1 and the output power of the external circuit, thus enhancing the performance of the battery 1. In other embodiments, the area of ​​the first active material region 202 may also be equal to the area of ​​the second active material region 203.

[0053] Please continue to refer to Figure 3In one embodiment, the size of the first active material region 202 along the first direction X1 is L1, and the size of the second active material region 203 along the first direction X1 is L2. L1 and L2 satisfy the following relationship: L2 < L1 ≤ 2 * L2. Optionally, L1 can be 1.2 * L2, 1.4 * L2, 1.6 * L2, or 1.8 * L2. Of course, L1 and L2 can also have other multiple relationships that satisfy the above range, which will not be listed one by one in this application. If the other direction parallel to the surface of the first electrode 20 and perpendicular to the first direction X1 is defined as the second direction Y, then the size of the first active material region 202 along the second direction Y is equal to the size of the second active material region 203 along the second direction Y. That is to say, when L1 is greater than L2, the area of ​​the first active material region 202 can be made larger than the area of ​​the second active material region 203, thereby correspondingly increasing the content of the first active material 22, thereby increasing the charge and discharge rate of the battery 1 and the output power of the external circuit, and improving the performance of the battery 1.

[0054] Compared with the size of the first tab 201 along the first direction X1, the size of the first active material region 202 along the first direction X1 can be larger than the size of the first tab 201 along the first direction X1, and the size of the second active material region 203 along the first direction X1 can be greater than, equal to or smaller than the size of the first tab 201 along the first direction X1.

[0055] It is worth noting that the size of the first electrode 20 along the first direction X1 can be greater than, equal to or less than the size of the first electrode 20 along the second direction Y.

[0056] Furthermore, the areal density of the first active material region 202 and the areal density of the second active material region 203 also differ. If the areal density of the first active material region 202 is denoted as P1, and the areal density of the second active material region 203 is denoted as P2, in one embodiment, P1 and P2 satisfy the following relationship: 0.8 ≤ P1 / P2 ≤ 1.1. Optionally, the value of P1 / P2 can be 0.85, 0.90, 0.95, 1.00, 1.05, or other values ​​satisfying the above range; these are not listed individually in this application.

[0057] The capacity per unit area of ​​the first active material region 202 is directly proportional to its areal density, and the capacity per unit area of ​​the second active material region 203 is directly proportional to its areal density. When P1 and P2 satisfy the above relationship, the difference between the capacity per unit area of ​​the first active material region 202 and the capacity per unit area of ​​the second active material region 203 can be reduced, so that the first active material region 202 and the second active material region 203 have similar capacities per unit area.

[0058] Taking the first electrode 20 as the positive electrode as an example, when there is a significant difference in capacity per unit area between the first active material region 202 and the second active material region 203 of the positive electrode, the delithiation capacity per unit area of ​​the two regions also differs significantly during charging. In other words, the amount of Li₂ deintercalated / intercalated in the first active material region 202 of the positive electrode per unit time and per unit area... + More, Li deintercalation / intercalation in the second active material region 203 + Less. However, when the lithium intercalation capability is relatively uniform throughout the entire negative electrode region, the side of the negative electrode corresponding to the first active material region 202 may not be able to accommodate a large amount of Li. + Lithium plating occurs.

[0059] In this application, by adjusting the areal density of the first active material region 202 and the areal density of the second active material region 203, the first active material region 202 and the second active material region 203 can have similar capacity per unit area, thereby improving the above-mentioned phenomenon.

[0060] In the first electrode 20, the first active material 22 and the second active material 23 can be disposed on one side or both sides. For example... Figure 2 As shown, in one embodiment, the first current collector 21 includes a first surface 211 and a second surface 212 arranged along the thickness direction. The portion of the first surface 211 corresponding to the first active material region 202 is covered by the first active material 22, and the portion of the first surface 211 corresponding to the second active material region 203 is covered by the second active material 23. The second surface 212 is not provided with the first active material 22 and the second active material 23.

[0061] like Figure 4 As shown, in another embodiment, the portions of the first surface 211 and the second surface 212 corresponding to the first active material region 202 are both covered by the first active material 22, and the portions of the first surface 211 and the second surface 212 corresponding to the second active material region 203 are both covered by the second active material 23. In the above embodiments, by distributing the first active material 22 and the second active material 23 on both surfaces of the first current collector 21, the content of the first active material 22 and the second active material 23 is increased, thereby improving the capacity of the battery 1.

[0062] The specific types of the first active material 22 and the second active material 23 include various forms. In one embodiment, the first active material 22 includes a ternary component, and the second active material 23 includes lithium manganese iron phosphate or lithium iron phosphate. Ternary materials include metal ions such as cobalt, nickel, and manganese, and have high specific capacity. Furthermore, ternary materials are easily converted by Li during charging and discharging. + Embedding also makes Li + Break away.

[0063] In the specific preparation of the first electrode 20, the first active material 22 can be mixed with a binder, a conductive agent, etc., to prepare a slurry, and then applied to the corresponding area on the surface of the first current collector 21. The second active material 23 can also be mixed with a binder, a conductive agent, etc., to prepare a slurry, and then applied to the corresponding area on the surface of the first current collector 21.

[0064] The aforementioned battery 1 can serve as an energy storage battery to provide power to electrical devices. Furthermore, because the various active materials contained in the first electrode 20 of the aforementioned battery 1 are arranged in separate zones, personnel can individually study the characteristics of these various active materials during the charging and discharging process, thereby adjusting the proportions and composition of these various active materials to improve the performance of the battery 1.

[0065] In order to study the characteristics of the first active material 22 and the second active material 23 during the charging and discharging process, in one embodiment, the battery 1 further includes a plurality of reference electrodes, which are electrically connected to different regions of the first electrode 20, thereby studying the characteristics of the active material in the corresponding regions during the charging and discharging process. Figure 5 This is a schematic diagram showing the connection between the reference electrode and the first electrode plate provided in an embodiment of this application, as shown below. Figure 5 As shown, in one embodiment, battery 1 includes a first reference electrode 30 and a second reference electrode 40, wherein the first reference electrode 30 is electrically connected to a first active material 22, and the second reference electrode 40 is electrically connected to a second active material 23. The first reference electrode 30 can monitor the electrode potential of the first active material 22, and the second reference electrode 40 can monitor the electrode potential of the second active material 23. After testing, the first active material 22 and the second active material 23 are easily separated, thereby facilitating the analysis of the physical properties of individual materials.

[0066] Please continue to refer to this. Figure 5 In one embodiment, the battery 1 further includes a third reference electrode 50, which is located at a critical position between the first active material region 202 and the second active material region 203. At the critical position, the first active material 22 and the second active material 23 are adjacent, thereby simulating the phenomenon of mixing of the first active material 22 and the second active material 23. The potential change in the mixed state can be monitored through the third reference electrode 50.

[0067] In addition to the first electrode 20, the battery 1 also includes a second electrode 60, a separator, and an electrolyte. The polarity of the second electrode 60 is opposite to that of the first electrode 20. For example, the second electrode 60 is the negative electrode, and the first electrode 20 is the positive electrode. The separator is located between the first electrode 20 and the second electrode 60. The separator is a polymer film with a microporous structure, allowing Li to pass through. +It allows electrons to pass through, but prevents them from passing through. The electrolyte acts as a transport medium, allowing Li... + Transmission occurs between the first electrode 20 and the second electrode 60.

[0068] When specifically setting the second electrode 60, the second electrode 60 includes various structures. Figure 6 This is a schematic diagram of a structure of the second electrode provided in an embodiment of this application, as shown below. Figure 6 As shown, in one embodiment, the second electrode 60 includes a second current collector 61, a third active material 62, and a fourth active material 63. The second current collector 61 serves to collect current and carry the third active material 62 and the fourth active material 63. The second current collector 61 can be copper foil or aluminum foil. The OI value of the third active material 62 is less than that of the fourth active material 63. The OI value is used to characterize the crystal orientation index of graphite particles and is the ratio of the peak intensity of the 004 peak to the 110 peak of graphite in the X-ray diffraction spectrum. The smaller the powder OI, the more uniform the graphite interlayer spacing, and the more perpendicular the graphite material structure is to the electrode, which is more conducive to lithium-ion transport. In other words, the smaller the OI value, the more favorable it is for lithium-ion diffusion. Or, the smaller the OI value, the stronger the lithium intercalation capability. Therefore, the lithium intercalation capability of the third active material 62 is greater than that of the fourth active material 63.

[0069] In one embodiment, the ratio of the OI value of the third active substance to the OI value of the fourth active substance is H, where H satisfies the following relationship: 0.4 ≤ H < 1. Optionally, the value of H can be 0.5, 0.6, 0.7, 0.8, or 0.9.

[0070] Figure 7 This is a schematic diagram showing the distribution of the active material contained in the second electrode sheet provided in an embodiment of this application, such as... Figure 7 As shown, based on the distribution of active materials, the second electrode 60 includes a second tab 601, a third active material region 602, and a fourth active material region 603. The surface of the second tab 601 has no active material distributed, while the third active material region 602 has a third active material 62 distributed thereon, and the fourth active material region 603 has a fourth active material 63 distributed thereon.

[0071] When specifically configuring the second tab 601, the second tab 601 can be the portion of the second current collector 61 not covered by the active material. Alternatively, the second tab 601 can also be a separate conductive structure. During charging and discharging, the second tab 601 can be connected to an external power source or electrical device.

[0072] In battery 1, a second electrode 60 and a first electrode 20 are alternately arranged. The third active material region 602 of the second electrode 60 is opposite to the first active material region 202 of the first electrode 20, and the fourth active material region 603 of the second electrode 60 is opposite to the second active material region 203 of the first electrode 20. During charging, the lithium insertion capability of the third active material 62 can match the lithium removal capability of the first active material 22, and the lithium insertion capability of the fourth active material 63 can match the lithium removal capability of the second active material 23. Taking the first active material 22 and the third active material 62 as an example, during charging, the Li... + It diffuses relatively quickly. A significant amount of Li... + After being extracted from the first active material 22, it will be transported through the electrolyte to the third active material region 602 of the second electrode 60. Because the third active material 62 has a strong lithium intercalation capability, it enables Li... + It can be embedded in the third active material 62 more quickly, thereby improving the charging rate.

[0073] Figure 8 This is a schematic diagram of the arrangement of the first and second electrodes provided in an embodiment of this application, as shown below. Figure 8 As shown, in one embodiment, the first tab 201 of the first electrode 20 and the second tab 601 of the second electrode 60 are both led out along a first direction X1. Regarding the first electrode 20, the first active material region 202 is adjacent to the first tab 201, and the second active material region 203 is located on the side of the first active material region 202 away from the first tab 201. Regarding the second electrode 60, the third active material region 602 is adjacent to the second tab 601, and the fourth active material region 603 is located on the side of the third active material region 602 away from the second tab 601, thereby allowing the third active material region 602 to be opposite to the first active material region 202 of the first electrode 20, and the fourth active material region 603 to correspond to the second active material region 203 of the first electrode 20.

[0074] Figure 9 Another schematic diagram of the arrangement of the first and second electrodes provided in the embodiments of this application is shown below. Figure 9 As shown, in one embodiment, the first electrode tab 201 of the first electrode 20 is led out along the first direction X1, and the second electrode tab 601 of the second electrode 60 is led out along the second direction X2. The first direction X1 and the second direction X2 are opposite.

[0075] Regarding the first electrode 20, the arrangement of the first active material region 202 and the second active material region 203 is as follows: Figure 8In the corresponding embodiments, the first active material region 202 and the second active material region 203 are arranged in the same way. Regarding the second electrode 60, the third active material region 602 and the fourth active material region 603 are arranged in the same way. Figure 8 In the corresponding embodiments, the third active material region 602 and the fourth active material region 603 are arranged differently. For example... Figure 9 As shown, in this embodiment, the fourth active material region 603 is adjacent to the second electrode tab 601, and the third active material region 602 is located on the side of the third active material region 602 away from the second electrode tab 601, so that the third active material region 602 can be opposite to the first active material region 202 of the first electrode 20, and the fourth active material region 603 can be corresponding to the second active material region 203 of the first electrode 20.

[0076] In one specific embodiment, along the lead-out direction of the second tab 601, the size of the third active material region 602 is larger than the size of the fourth active material region 603. As an example, the orthographic projection of the third active material region 602 onto the plane where the first electrode 20 is located can completely cover the first active material region 202, and the orthographic projection of the fourth active material region 603 onto the plane where the first electrode 20 is located can completely cover the second active material region 203.

[0077] In the second electrode 60, in addition to partitioning the third active material 62 and the fourth active material 63 on the surface of the second current collector 61, the third active material 62 and the fourth active material 63 can also be doped and uniformly coated on the surface of the second current collector 61.

[0078] Based on the same technical concept, this utility model embodiment also provides a battery device. Figure 10 This is a schematic diagram of a battery device provided in an embodiment of this application, such as... Figure 10 As shown, the battery device includes a housing 2 and a plurality of batteries 1 located inside the housing 2.

[0079] In the aforementioned battery device, battery 1 includes a first electrode 20, which includes a first active material 22 and a second active material 23. The first active material 22 and the second active material 23 are not mixed but are arranged in different regions. Taking the first tab 201 as a reference, the first active material 22 is arranged in the first active material region 202, which is closer to the first tab 201, and the second active material 23 is arranged in the second active material region 203, which is farther from the first tab 201. The current density of the first active material region 202 is greater than the current density of the second active material region 203. This is because the Li of the first active material 22... + Li has strong diffusion ability; therefore, within the first active material region 202, Li +The diffusion rate can match the higher current density, thereby improving the battery's charge / discharge rate and the output power of the external circuit. Furthermore, if the second active material 23 is distributed in the first active material region 202 with a higher current density, then due to the Li of the second active material 23... + Its poor diffusion ability easily leads to a mismatch between ion and electron transport, thus initiating lithium plating. Therefore, Li... + The second active material 23, which has weak diffusion ability, is distributed in the second active material region 203 far away from the first electrode 201, which can make the transport of ions and electrons more matched, thereby reducing the risk of lithium plating.

[0080] This application provides a Li + A method for testing the diffusion coefficient, comprising the following steps:

[0081] Disassemble the empty battery and remove the positive electrode, negative electrode, electrolyte, and separator;

[0082] The first active material region 202 and the second active material region 203 are each separated into 10*10mm electrode sheets, which are then reassembled with the separated separator, negative electrode and electrolyte into a single cell.

[0083] Perform CV tests at different scan speeds between 2.0 and 4.5V, record the scan speed v and Ip, plot Ip against v1 / 2, and the slope is the DLi. + Where Ip is the peak current obtained from the CV curve.

[0084] This application also provides a method for testing the upper limit voltage, which includes the following steps:

[0085] Disassemble the empty battery and remove the electrodes, separator, and electrolyte.

[0086] The first active material region 202 and the second active material region 203 are cut into 10*10mm electrode sheets and reassembled with the separator and electrolyte into a single cell.

[0087] The reassembled single battery cell was charged and discharged at 0.05C between 2.0 and 4.5V. In the entire charge and discharge range, when dV / dSOC > 10 within 0.3V (dV is the voltage V2 at the second moment of the charge and discharge process minus V1 at the first moment, and dSOC is the SOC at the second moment minus the SOC at the first moment), the initial V1 can be considered as the upper limit voltage of the battery.

[0088] This application also provides a method for testing OI values, which includes the following steps:

[0089] Disassemble the empty battery, remove the negative electrode, soak it in dimethyl carbonate (DMC) solution for 2 hours, remove it, air dry it, and then scrape off the powder.

[0090] X-ray diffraction (XRD) test: Weigh 1.0–2.0 g of sample and pour it into the groove of the glass sample holder. Press and smooth the sample with a glass slide. Perform the test using an X-ray diffractometer (Brook, D8) according to JJSK0131-1996 "General Rules for X-ray Diffraction Analysis". The test voltage is set to 40 kV, the current to 30 mA, the scanning angle range to 10–85°, the scanning step size to 0.0167°, and the time set for each step to 0.24 s. The OI value is obtained by calculating the ratio of the peak intensity of (004) peak to that of (110) peak in the XRD diffraction peaks.

[0091] Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A battery, characterized in that, It includes a housing and a first electrode, wherein the first electrode is located inside the housing; The first electrode includes a first tab, a first active material region, and a second active material region. The second active material region and the first active material region are arranged sequentially along the lead-out direction of the first tab. The first active material region contains a first active material, and the second active material region contains a second active material. The Li of the first active material... + The diffusion coefficient is DLi + 1, the Li of the second active substance + The diffusion coefficient is DLi + 2, the DLi + 1 and the DLi + 2. Satisfies the following relationship: DLi + 1>DLi + 2.

2. The battery as described in claim 1, characterized in that, The DLi + 1 and the DLi + 2 satisfies the following relationship: 1.0 < DLi + 1 / DLi + 2≤2.

0.

3. The battery as described in claim 1, characterized in that, Along the lead-out direction of the first tab, the size of the first active material region is L1, and the size of the second active material region is L2. The L1 and L2 satisfy the following relationship: L2 < L1 ≤ 2L2.

4. The battery according to any one of claims 1 to 3, characterized in that, The areal densities of the first active material region are P1 and the areal densities of the second active material region are P2. The P1 and P2 satisfy the following relationship: 0.8≤P1 / P2≤1.

1.

5. The battery according to any one of claims 1 to 3, characterized in that, The upper limit voltage of the first active substance is V1, and the upper limit voltage of the second active substance is V2. V1 and V2 satisfy the following relationship: V1 > V2.

6. The battery according to any one of claims 1 to 3, characterized in that, The battery also includes a second electrode, which is a negative electrode, and the first electrode is a positive electrode. The second electrode includes a second tab, a third active material region, and a fourth active material region, wherein the third active material region is opposite to the first active material region, and the fourth active material region is opposite to the second active material region; The third active substance region contains a third active substance, and the fourth active substance region contains a fourth active substance; the OI value of the third active substance is less than the OI value of the fourth active substance.

7. The battery as described in claim 6, characterized in that, The ratio of the OI value of the third active substance to the OI value of the fourth active substance is H, and H satisfies the following relationship: 0.4 ≤ H < 1.

8. The battery as described in claim 6, characterized in that, Along the lead-out direction of the second electrode, the size of the third active material region is larger than the size of the fourth active material region.

9. The battery according to any one of claims 1 to 3, characterized in that, The housing includes a housing body and a cover plate assembly, the housing body having an opening, the cover plate assembly covering the opening, and the cover plate assembly including a pole post; The first electrode is located inside the housing body, and the first electrode tab is electrically connected to the housing body; or, the first electrode tab is electrically connected to the electrode post.

10. A battery device, characterized in that, It includes a housing and a plurality of batteries as described in any one of claims 1 to 9, wherein the plurality of batteries are located within the housing.

Images