A positive grid for traction batteries

Abstract

A positive grid for traction battery, comprising a current collector upper frame; the upper side of the current collector upper frame is provided with a tab; the lower side of the current collector upper frame is provided with a row of evenly distributed current collector plugs; the lower side of each current collector plug is provided with a corresponding columnar lead bar; the lead bar is externally provided with a row pipe; the cross section of the lead bar is a cross structure; a cavity for accommodating active material is formed between the outer wall of the cross-shaped lead bar and the row pipe; the current collector upper frame is a truncated pyramid structure with a small upper side and a large lower side; the width of the lower side of the current collector upper frame is greater than the diameter of the current collector plug. The weight of the grid is reduced by 15-30% based on the existing basis, the plug part is improved, the active material precipitation at the plug part is reduced, the battery life is prolonged, and the purpose of reducing cost and prolonging life is achieved.

Description

Technical Field

[0001] This utility model belongs to the field of lead-acid battery manufacturing technology, specifically relating to a positive grid for traction batteries. Background Technology

[0002] Lead-acid batteries for traction are mainly used as power sources for electric vehicles, especially electric traction vehicles or material handling equipment. These batteries have advantages such as large capacity, excellent discharge performance, and long lifespan. Currently, batteries that fail due to powder precipitation and short circuits account for more than 50% of total returns, and their actual lifespan has decreased from the standard 1200-1500 cycles to around 1000 cycles, a mere 3 years. Lithium-ion batteries, on the other hand, have the advantages of fast charging and long lifespan, with an actual lifespan of around 5 years. This has led to a significant decline in the market share of lead-acid power batteries. Although the proportion of lead-acid batteries is decreasing, they still have irreplaceable advantages in certain specific applications. Market feedback indicates that lead-acid power batteries currently still hold over 70% of the market share. Currently, lithium-ion batteries are 1.5 to 1.8 times more expensive than lead-acid batteries. If lead-acid power batteries can improve their lifespan, reduce production costs, and enhance their cost-effectiveness, their market share still has room to recover.

[0003] Conventional positive plate designs typically employ a tubular structure, using a grid system with a lead rib connected to the current collector via a tab. The lead rib is placed in the center of a tube made of organic fiber, and the active material is filled between the tube wall and the central lead rib, thus offering advantages such as large capacity and long lifespan.

[0004] The positive grid of a traction battery consists of tabs, current collectors (upper frame), current collector plugs, and lead reinforcing bars. The plugs not only serve as current collectors during discharge but also prevent lead paste from overflowing during extrusion; the plug diameter is no less than the inner diameter of the tube. During actual battery use, the positive electrode active material undergoes a conversion from lead dioxide to lead sulfate. Because lead sulfate has a higher specific volume than lead dioxide, the volume of the positive electrode active material increases, ultimately expanding the tube and increasing the gap between the tube and the plug. Furthermore, during this conversion, the porosity of the electrode plate increases with the number of cycles, leading to severe expansion of the active material, excessive porosity, and reduced interparticle bonding. Ultimately, some of the active material softens and detaches, precipitating out from the gap between the tube and the plug, thus reducing battery life.

[0005] To maintain a long battery life, the lead reinforcement bars in the grid are designed to be cylindrical, with a diameter typically between 3.0 and 4.0 mm. According to test data, the corrosion rate of lead-antimony alloy grids is generally 0.00065 mm / day. Assuming a traction battery lifespan of 1500 days, the corrosion amount of the lead reinforcement bars is only 1-2 mm. The excessively large lead reinforcement bar size is merely a requirement for grid forming and production yield, resulting in high lead consumption at the reinforcement bar area and increased material costs. Furthermore, the cylindrical lead reinforcement bars have a small contact area with the active material. During continuous high-current discharge, the high current density at the interface between the lead reinforcement bars and the active material easily leads to localized overheating, damaging the corrosion layer and shortening the grid's lifespan, thus reducing battery life. Summary of the Invention

[0006] The purpose of this utility model is to overcome the shortcomings of the prior art and provide a positive grid for traction batteries.

[0007] A positive grid for a traction battery, including a current collector upper frame;

[0008] The upper side of the upper frame of the current collector is provided with a tab;

[0009] The upper frame of the current collector is provided with a row of evenly distributed current collector plugs. Each current collector plug is provided with a corresponding columnar lead rib on its lower side. A pipe is provided outside the lead rib. The cross-section of the lead rib is a cross-shaped structure. A cavity for accommodating active substances is formed between the outer wall of the cross-shaped lead rib and the pipe.

[0010] The upper frame of the current collector is a frustum structure with a smaller upper part and a larger lower part, and the lower width of the upper frame of the current collector is greater than the diameter of the current collector plug.

[0011] The upper width of the current collector's upper frame is the same as the width of the tab.

[0012] The upper end of the pipe is fitted onto the manifold plug.

[0013] The width of the lower side of the upper frame of the current collector is at least the width of the exhaust pipe after being expanded by the active material.

[0014] The lower width of the upper frame of the current collector is 0.1~0.3mm larger than the diameter of the current collector plug.

[0015] The lower side of the manifold plug is a truncated cone with a gradually decreasing diameter.

[0016] The utility model's grid upper frame cross-section is designed as a trapezoidal structure, with the bottom width of the trapezoid being 0.1~0.3mm wider than the diameter of the plug. The active material precipitated from the gap between the plug and the pipe is blocked by the bottom surface of the upper frame, reducing the amount of precipitation and achieving double protection, which is equivalent to improving battery life. The cross-section of the lead reinforcement is changed from the current "cylindrical" structure to a "cross-shaped" structure, which not only reduces the weight of the lead reinforcement but also increases the contact area between the grid and the active material, reduces the current density at the interface between the lead reinforcement and the active material, reduces the corrosion of the lead reinforcement, and improves battery life.

[0017] The weight of the grid in this utility model is reduced by 15-30% compared to existing models. At the same time, the end cap is improved to reduce the precipitation of active material at the end cap, thereby extending battery life and achieving the goal of both reducing costs and increasing lifespan. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the utility model structure;

[0019] Figure 2 for Figure 1 Side view;

[0020] Figure 3 for Figure 2 A magnified view of a portion of the image;

[0021] Figure 4 This is a cross-sectional view of the lead reinforcement. Detailed Implementation

[0022] This utility model is a cost-reducing positive plate grid for traction batteries.

[0023] like Figure 1-4 As shown, this utility model consists of an electrode tab 1, a current collector upper frame 2, a current collector plug 3, and lead ribs 4, all made of lead alloy and die-cast. There can be 15 to 19 lead ribs 4. The length of the grid ribs can be cut to different sizes according to the electrode capacity. The electrode tab 1 is connected to the upper side of the current collector upper frame 2. A row of evenly distributed current collector plugs 3 is provided on the lower side of the current collector upper frame 2. Each current collector plug 3 has a corresponding columnar lead rib 4 on its lower side. A pipe is provided outside the lead rib 4. The cross-section of the lead rib 4 is a cross-shaped structure, and a cavity for accommodating active substances is formed between the outer wall of the cross-shaped lead rib 4 and the pipe.

[0024] The upper frame 2 of the current collector is a frustum structure with a smaller top and a larger bottom. The lower width of the upper frame 2 of the current collector is greater than the diameter of the current collector plug 3, and the upper width of the upper frame 2 of the current collector is the same as the width of the tab 1.

[0025] like Figure 2As shown, the lower width of the upper frame 2 of the current collector is 0.1~0.3mm larger than the diameter of the current collector plug 3. Even during the conversion of active material, the porosity of the plate increases with the increase of the number of cycles, the active material expands severely, the porosity increases excessively, the binding force between particles decreases, and eventually some active material softens and falls off, precipitating out from the gap between the pipe and the plug. The precipitated active material is blocked by the bottom surface of the upper frame 2 of the current collector, reducing the amount of precipitation, achieving double protection, which is equivalent to improving battery life.

[0026] like Figure 3 As shown, the manifold plug is a solid frustum, distributed at equal intervals on the lower part of the upper frame 2 of the manifold. The lower side of the manifold plug 3 is a frustum cone with a gradually decreasing diameter, and is connected to the lower lead rib.

[0027] like Figure 4 As shown, the lead reinforcement 4 consists of multiple strips with the same structure, and is connected to the lower end of the manifold plug 3. The cross-section of the lead reinforcement is "cross-shaped".

Claims

1. A positive grid for a traction battery, characterized in that: Including the upper frame of the current collector (2); The upper side of the current collector upper frame (2) is provided with a tab (1); The upper frame (2) of the current collector is provided with a row of evenly distributed current collector plugs (3), and each current collector plug (3) is provided with a corresponding columnar lead rib (4) on its lower side. The lead rib (4) is provided with a pipe, and the cross section of the lead rib (4) is a cross-shaped structure. A cavity for accommodating active substances is formed between the outer wall of the cross-shaped lead rib (4) and the pipe. The upper frame (2) of the current collector is a frustum structure with a smaller upper part and a larger lower part. The lower width of the upper frame (2) of the current collector is greater than the diameter of the current collector plug (3).

2. The positive grid for a traction battery according to claim 1, characterized in that: The upper width of the upper frame (2) of the current collector is the same as the width of the tab (1).

3. The positive grid for a traction battery according to claim 1, characterized in that: The upper end of the pipe is fitted onto the manifold plug (3).

4. A positive grid for a traction battery according to claim 1, 2 or 3, characterized in that: The width of the lower side of the upper frame (2) of the current collector is at least the width of the exhaust pipe after being expanded by the active substance.

5. The positive grid for a traction battery according to claim 1, characterized in that: The lower width of the upper frame (2) of the current collector is 0.1~0.3mm larger than the diameter of the current collector plug (3).

6. The positive grid for a traction battery according to claim 1, characterized in that: The lower side of the collector plug (3) is a truncated cone with a gradually decreasing diameter.

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