High-capacity nickel-metal hydride battery

Abstract

The utility model discloses a high-capacity nickel-metal hydride battery which structurally comprises a shell and a laminated core, the laminated core comprises a negative plate, a diaphragm and a positive plate which are sequentially laminated, one edge of the positive plate and the negative plate is provided with a tab, and the tab is positioned on two opposite side edges of the laminated core after the laminated core is manufactured. Grooves parallel to the sides where the tabs are located are formed in the coating faces of the two sides of the positive plate or the negative plate, active substances are not coated in the grooves, and the grooves form a water channel in the stacked core. According to the utility model, the grooves parallel to the edges of the tabs are arranged on the pole pieces, and the water channels capable of storing the electrolyte are formed in the laminated core after assembly, so that the infiltration path from the electrolyte to the pole pieces and the diaphragm is shortened, the infiltration time before activation is shortened, heat generated during charging and discharging is quickly guided out, the internal temperature of the battery is reduced, and the service life of the battery is prolonged. The swelling amount of active substances of the pole piece during charging can be absorbed, battery failure caused by wrinkles of the pole piece is avoided, and the nickel-metal hydride battery adopting the structure has the characteristics of large pole piece size, high first activation efficiency, large design capacity, low failure risk and the like.

Description

Technical Field

[0001] The utility model belongs to the technical field of nickel-metal hydride battery preparation, and particularly relates to a large-capacity nickel-metal hydride battery. Background Art

[0002] With the popularization of new energy vehicles and the rapid spread of energy storage systems, as a core component, the volume energy density of new energy batteries is required to be higher and higher. Compared with the current mainstream lithium batteries, nickel-metal hydride batteries have the characteristics of high-power discharge and high safety, and still have a relatively wide range of application fields. However, the energy density of nickel-metal hydride batteries is far lower than that of lithium batteries, and the application scenarios are limited to a certain extent. To make the energy density of nickel-metal hydride batteries as close as possible to that of lithium batteries, only ultra-large-capacity batteries can be made, and the electrodes with large width and large thickness are used to make the batteries. However, the too-wide and too-thick electrodes are not conducive to the penetration of the electrolyte into the middle of the electrodes, which affects the reaction speed of the effective substances in the battery and reduces the charge and discharge capacity of the battery; it is also not conducive to the heat release during the charge and discharge process of the electrodes and the absorption of the expansion amount of the active substances, increasing the risk of battery failure. Summary of the Utility Model

[0003] The purpose of the utility model is to provide a large-capacity nickel-metal hydride battery to solve the situation that the existing nickel-metal hydride batteries are limited by the size of the electrodes and cannot prepare large-capacity batteries or the prepared large-capacity batteries are prone to failure.

[0004] The utility model is realized by the following technical solutions:

[0005] The utility model provides a large-capacity nickel-metal hydride battery, the structure of which includes a shell and a stacked core. The stacked core includes a negative electrode sheet, a separator and a positive electrode sheet stacked in sequence. One side of the positive electrode sheet and the negative electrode sheet is provided with a tab. The tabs of the positive electrode sheet and the negative electrode sheet are respectively arranged on two opposite sides of the stacked core. At least one group of grooves is provided on the coated surfaces on both sides of the positive electrode sheet or the negative electrode sheet. The grooves are parallel to the side where the tab of the positive electrode sheet or the negative electrode sheet is located. The grooves are not coated with active substances, and the grooves form a water channel in the stacked core.

[0006] Based on the above technical solutions, by arranging a water channel in the stacked core, on the one hand, it is conducive to promoting the rapid penetration of the electrolyte into the electrode sheets before activation, increasing the wettability of the separator, improving the effective utilization rate of the active substances on the positive and negative electrode sheets and ensuring the effective activation of the battery capacity; on the other hand, it is conducive to quickly discharging the heat generated during the charge and discharge process, reducing the internal temperature of the battery, and absorbing the expansion amount of the active substances on the electrode sheets during charging, avoiding the risk of battery failure such as short circuit and thermal runaway caused by the wrinkling of the electrode sheets, effectively solving the problems of low first activation efficiency and high battery failure risk of large-capacity nickel-metal hydride batteries using large-width and large-thickness electrode sheets, and further improving the design capacity of nickel-metal hydride batteries, realizing the preparation of large-capacity nickel-metal hydride batteries with low failure risk.

[0007] Preferably, the grooves are equidistantly distributed on the positive electrode sheet or the negative electrode sheet, and divide the coated surface of the positive electrode sheet or the negative electrode sheet into a plurality of active areas of equal area. This design is conducive to promoting the uniformity of the wetting of the electrode sheet and the diaphragm, and the uniform absorption of the expansion during the charging and discharging process, and avoiding deformation of the electrode sheet due to uneven force.

[0008] Preferably, the grooves are provided on the coated surfaces of the positive electrode sheet and the negative electrode sheet. After the stacked core is assembled, the grooves at corresponding positions on the positive electrode sheet and the negative electrode sheet overlap with each other to form the water channel. This design can widen the depth of the water channel and increase the capacity of the water channel.

[0009] Preferably, the groove is formed by the thickness difference between the positive electrode sheet and the negative electrode sheet when the active material is not coated at the groove position, and the groove depth is the sum of the thickness of the active material coating layer of the positive electrode sheet and the negative electrode sheet. This design can simplify the electrode manufacturing process.

[0010] Preferably, the positive electrode sheet and the negative electrode sheet are made of a compressible electrode sheet substrate, and the electrode sheet substrate is pre-pressed at a preset position to form the groove. The depth of the groove is determined by the sum of the compression amount of the electrode sheet substrate and the coating thickness of the active material of the positive electrode sheet or the negative electrode sheet. This design can expand the volume of the water channel and achieve better heat dissipation effect.

[0011] Furthermore, the compressible pole piece substrate is nickel foam.

[0012] Beneficial Effects

[0013] The beneficial effects of the utility model are:

[0014] By arranging grooves parallel to the sides where the pole ears are located on the positive and negative pole sheets, water channels are formed in the stacked core after the positive and negative poles are alternately stacked. On the one hand, this design stores electrolyte through the water channels and shortens the infiltration path of the electrolyte to the pole sheets and the diaphragm, which is beneficial to promote the rapid penetration of the electrolyte into the pole sheets before activation, increase the wettability of the diaphragm, improve the effective utilization rate of the active materials of the positive and negative pole sheets, and ensure the effective activation of the battery capacity; on the other hand, it is beneficial to quickly conduct the heat generated during the charging and discharging process, reduce the internal temperature of the battery, and absorb the expansion of the active materials of the pole sheets during charging, so as to avoid the wrinkles of the pole sheets, resulting in battery short circuit, thermal runaway and other failure risks; through simple structural changes, the problems of low first activation efficiency and high battery failure risk of large-capacity nickel-hydrogen batteries using large-width and large-thickness pole sheets are effectively solved, the thickness and width of the pole sheets can be further increased, and then the design capacity of the nickel-hydrogen battery is improved, and the effective preparation of large-capacity nickel-hydrogen batteries with low failure risk is realized. The nickel-hydrogen battery using the pole sheet with grooves has the characteristics of large pole sheet size, high first activation efficiency, large design capacity, low failure risk, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Other features, objects, and advantages of the present utility model will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0016] Figure 1 It is a schematic structural diagram of the first embodiment of the present utility model;

[0017] Figure 2 For the present utility model Figure 1 It is a schematic structural diagram of the AA cross-section in the present utility model;

[0018] Figure 3 For the present utility model Figure 2 It is a schematic structural diagram of part B in the present utility model;

[0019] Figure 4 It is a schematic structural diagram of the pole piece of the first embodiment of the present utility model;

[0020] Figure 5 It is a schematic cross-sectional structural diagram of the second embodiment of the present utility model;

[0021] Figure 6 For the present utility model Figure 5 It is a schematic structural diagram of part C in the present utility model;

[0022] In the figure: housing 1; stacked core 2; negative electrode sheet 21; separator 22; positive electrode sheet 23; tab 3; groove 4; water channel 40; first groove 41; second groove 42. Specific embodiments

[0023] The present utility model will be further described in detail below in conjunction with embodiments, but the embodiments of the present utility model are not limited thereto.

[0024] Embodiment 1

[0025] As Figures 1 to 3 shown, the present utility model provides a high-capacity nickel-metal hydride battery, the structure of which includes a housing 1 and a stacked core 2. The stacked core 2 includes a negative electrode sheet 21, a separator 22, and a positive electrode sheet 23 stacked in sequence. The positive electrode sheet 23 and the negative electrode sheet 21 are made of a compressible electrode substrate such as nickel foam. One side of the positive electrode sheet 23 and the negative electrode sheet 21 is provided with a tab 3. The tabs 3 of the positive electrode sheet 23 and the negative electrode sheet 21 are respectively arranged on two opposite sides of the stacked core 2. At least one group of grooves 4 is provided on the coated surfaces on both sides of the positive electrode sheet 23 or the negative electrode sheet 21. The same group of grooves 4 is arranged opposite to each other on the two coated surfaces of the positive electrode sheet 23 or the negative electrode sheet 21. As Figure 2 and Figure 3As shown, the two sets of grooves 4 are provided on the positive electrode plate 23. The grooves 4 are parallel to the side where the tabs 3 of the positive electrode plate 23 or the negative electrode plate 21 are located, and no active material is coated in the grooves 4. The grooves 4 are formed by pre-pressing the electrode plate substrate at a preset position. The depth of the grooves 4 is the sum of the compression amount of the electrode plate substrate and the coating thickness of the active material on the positive electrode plate 23 or the negative electrode plate 21. The forming process of the grooves 4 includes: (1) Before coating the active material, use a tool or equipment to pre-press inward from both sides of the electrode plate substrate at a preset position, so that the thickness of the electrode plate substrate at the pre-pressed position is less than the normal thickness of the electrode plate substrate, and then a set of channels with a certain height difference is formed on the surface of the electrode plate substrate; (2) Stick a tape on the formed channels, coat the active material slurry on the electrode plate substrate by spraying or doctor blading, etc., and remove the tape after the active material is cured, that is, the grooves 4 are formed. Optionally, in this step, the active material slurry can also be coated first and then the active material at the pre-pressed position can be washed away with water to obtain the grooves 4.

[0026] Preferably, the grooves 4 are equally spaced on the positive electrode plate 23 or the negative electrode plate 21, and the coating surface of the positive electrode plate 23 or the negative electrode plate 21 is divided into multiple active areas with equal areas, which promotes the uniform wetting of the electrode plate and the separator 22, and the uniform absorption of the swelling amount during the charge and discharge process. As Figure 2 shown, after the positive electrode plate 23 and the negative electrode plate 21 are alternately stacked, the grooves 4 form a water channel 40 in the stacked core 2. In actual design, the width and the number of the grooves 4, that is, the width and the number of the water channel 40, are comprehensively determined according to the size of the electrode plate and the coating thickness of the active material. As Figure 4 shown, there are two grooves 4 on the electrode plate, which divide the electrode plate into two equal parts.

[0027] The beneficial effects and implementation mechanisms of the technical solution of this embodiment are as follows:

[0028] 1. By adding a water channel 40 in the middle of the electrode plate, the capacity and flow resistance of the electrolyte are smaller, which is beneficial to the electrolyte to penetrate more quickly into the middle of the separator 22 and the electrode plate, and improve the activation efficiency. On the one hand, the positive and negative electrode plates 21 of the nickel-metal hydride battery can only be activated after the electrolyte completely penetrates. The un-wetted electrode plate cannot carry out electrochemical reactions, and the active material fails, resulting in battery capacity loss. On the other hand, during the time process of electrolyte wetting, it is easy for effective substances such as cobalt powder, carbon powder, and rare earth materials outside the electrode plate to precipitate into the electrolyte and cannot be fixed on the electrode plate, losing their due functions and affecting the capacity performance. And the un-sufficiently wetted separator 22 will increase the ion migration resistance, resulting in an increase in the internal resistance of the battery, and the heat generated during the charge and discharge process also increases correspondingly, and the risk of battery failure rises.

[0029] 2. By adding a water channel 40 in the middle of the electrode plate, the rapid heat transfer is achieved by utilizing the fluidity of the electrolyte, reducing the risk of thermal failure. During the charging and discharging of the battery, the generated heat can be dissipated from the inside of the battery to the battery case 1 faster, thereby reducing the internal temperature of the battery, decreasing the thermal failure rate of the active material, and further increasing the battery life.

[0030] 3. By adding a water channel 40 in the middle of the electrode plate, a storage space for the electrolyte is provided to release the stress generated by the expansion of the electrode plate during charging. During the charging process, the active material on the nickel-metal hydride battery electrode plate will expand, and the free electrolyte between the electrode plates and the electrolyte on the separator 22 will be squeezed out. The water channel 40 can provide a storage space for discharging the electrolyte, avoiding the short circuit of the battery caused by the electrode plate wrinkles due to the inability to discharge the electrolyte or the untimely discharge. During the discharging process, the active material on the electrode plate retracts, and the electrolyte in the water channel 40 can quickly flow back between the electrode plates and onto the separator 22, avoiding the increase in ion migration resistance, and further increasing the battery life.

[0031] Based on the above effects, the problems existing in the large-capacity nickel-metal hydride battery with large-width and large-thickness electrode plates can be solved only by the simple design of setting the water channel 40 in the middle of the electrode plate, which is beneficial to further expanding the size and thickness of the electrode plate, and further allowing the preparation of nickel-metal hydride batteries with larger design capacities.

[0032] Embodiment 2

[0033] This embodiment provides a large-capacity nickel-metal hydride battery, which is different from Embodiment 1 in that:

[0034] As Figure 5 and Figure 6 shown, the grooves 4 are provided on the coating surfaces of both the positive electrode plate 23 and the negative electrode plate 21. The groove 4 includes a first groove 41 provided on the negative electrode plate 21 and a second groove 42 provided on the positive electrode plate 23. After the stacked core 2 is assembled, the first groove 41 and the second groove 42 overlap with each other to jointly form the water channel 40, so as to further broaden the depth of the water channel 40 and increase the capacity of the water channel 40.

[0035] As Figure 6 shown, two groups of first grooves are provided on the positive electrode plate 21. The groove 4 is jointly constituted by the thickness difference formed by not coating the active material at the position of the groove 4 on the positive electrode plate 23 and the negative electrode plate 21 and the height difference formed by pre-pressing the electrode plate matrix. The depth of the groove 4 is the sum of the thickness of the active material coating layers of the positive electrode plate 23 and the negative electrode plate 21, and the height difference of the electrode plate matrix with the pressure difference.

[0036] The structures, components, and the relationships between components not described in this embodiment are the same as those in Embodiment 1.

[0037] The above are only the preferred embodiments of the present utility model, and do not impose any limitation on the technical scope of the present utility model. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present utility model still fall within the protection scope of the present utility model.

Claims

1. A high-capacity nickel-metal hydride battery, whose structure comprises a housing and a stacked core. The stacked core includes a negative electrode plate, a separator, and a positive electrode plate stacked in sequence. One side of the positive electrode plate and the negative electrode plate is provided with a tab. The tabs of the positive electrode plate and the negative electrode plate are respectively arranged on two opposite sides of the stacked core, and it is characterized in that: At least one set of grooves is provided on both coating surfaces of the positive electrode sheet or the negative electrode sheet. The grooves are parallel to the side where the tab of the positive electrode sheet or the negative electrode sheet is located. No active material is coated in the grooves, and the grooves form a water channel in the stacked core.

2. The high-capacity nickel-hydrogen battery according to claim 1, wherein: The grooves are equally spaced on the positive electrode sheet or the negative electrode sheet, and the coating surface of the positive electrode sheet or the negative electrode sheet is divided into a plurality of active regions with equal areas.

3. A high-capacity nickel-metal hydride battery according to claim 1, characterized in that: The grooves are provided on the coating surfaces of both the positive electrode sheet and the negative electrode sheet. After the stacked core is assembled, the grooves at corresponding positions on the positive electrode sheet and the negative electrode sheet overlap with each other to jointly form the water channel.

4. A high-capacity nickel-metal hydride battery according to claim 3, characterized in that: The grooves are formed by the thickness difference formed by not coating the active material at the groove positions on the positive electrode sheet or the negative electrode sheet. The depth of the grooves is the sum of the thicknesses of the active material coating layers of the positive electrode sheet and the negative electrode sheet.

5. A high-capacity nickel-metal hydride battery according to claim 1, characterized in that: The positive electrode sheet and the negative electrode sheet are made of a compressible electrode substrate. The electrode substrate is pre-pressed at a preset position to form the grooves. The depth of the grooves is the sum of the compression amount of the electrode substrate and the coating thickness of the active material on the positive electrode sheet or the negative electrode sheet.

6. A high-capacity nickel-metal hydride battery according to claim 5, characterized in that: The compressible electrode substrate is nickel foam.

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