Needle eye ring current collector and high-liquid-absorption-rate positive plate applying same

Abstract

The invention relates to the technical field of button cells, and particularly discloses a needle eye ring current collector and a high-liquid-absorption-rate positive plate applying the same. The needle eye ring current collector comprises a substrate and a ring extending upwards on the periphery of the substrate, a liquid suction hole and a plurality of needle eye holes annularly formed in the periphery of the liquid suction hole are formed in the substrate, and the needle eye holes protrude towards one side of the extending direction of the ring. The positive plate comprises a needle eye ring current collector, a substrate and a ring of the needle eye ring current collector define a containing cavity, positive powder and electrolyte are contained in the containing cavity, at least part of the positive powder is exposed in the liquid suction holes, and the needle eye hole protrusions penetrate into the positive powder. According to the needle eye ring current collector structure disclosed by the invention, the liquid absorption rate of the positive electrode is quickly improved while the conductivity is ensured, so that the internal resistance of the battery is prevented from being too quickly increased due to insufficient electrolyte in the discharging process, and the problems that the discharging time of a traditional button battery is relatively short and the capacity release amount is low under 10mA large-current pulse are solved.

Description

Technical Field

[0001] The invention relates to the technical field of button batteries, and specifically discloses a pinhole ring current collector and a positive electrode sheet with a high liquid absorption rate using the current collector ring. Background Art

[0002] The rated voltage of lithium manganese battery is 3.0 volts, which is about twice that of dry cell battery. It has stable discharge voltage, good storage performance, good high rate discharge performance, good fast pulse discharge performance and wide operating temperature. The product is safe and environmentally friendly. Therefore, it is widely used in digital cameras, portable computers, PDAs, various smart card meters (water meters, electricity meters, gas meters), alarm systems, emergency lights, medical equipment, remote control equipment and toys.

[0003] However, the current collector of the positive electrode of the conventional lithium manganese primary battery is a stainless mesh or a bowl-shaped collector, as shown below Figure 1 and Figure 2 As shown. Both of the above two positive electrodes have their own problems. Figure 1 The mesh collector fluid is prone to edge breakage during the production process, thus affecting the capacity of the positive electrode; Figure 2 Although the bowl-shaped current collector can well protect the positive electrode from damage during the production process, its current collection capacity is still not ideal. Under the condition of 10mA high current pulse discharge, the battery release capacity is low and the discharge time is short, which cannot meet the user's usage needs. Therefore, it is necessary to propose a new button battery current collector structure to improve the capacity and capacity release rate of lithium-manganese dioxide button batteries under high current pulse mode. Summary of the invention

[0004] With the development of electronic information technology in recent years, higher requirements have been put forward for various aspects of battery performance, especially for the high current discharge capacity of batteries. For example, the IEC standard adds a 10mA high current pulse performance requirement for the lithium manganese button battery model CR2032, specifically: 10mA discharge for 5s, rest for 55s, continuous discharge until the battery voltage reaches 1.8V, and the battery is required to be discharged for at least 12.5h (that is, the average discharge time in the 10mA mode is 12.5h, and the corresponding battery discharge capacity is 125mAh).

[0005] At present, the discharge time of the commonly used lithium-manganese dioxide button batteries on the market is generally 13 to 17 hours under the 10mA high current pulse mode (corresponding to a discharge capacity of 130 to 170mAh, and the released capacity is only 57.8% to 75.6% of the designed capacity). The discharge time is short and the discharge capacity cannot meet the user's usage needs.

[0006] Through research and analysis, it was found that the reason why the release capacity of 10mA pulse discharge is not high is that the internal resistance rises rapidly in the middle and late stages of discharge. The fundamental reason is the lack of electrolyte inside the battery. Therefore, while ensuring good conductivity of the positive electrode, improving the liquid absorption rate of the positive electrode is the key.

[0007] The object of the present invention is to overcome the deficiencies of the prior art and to provide a pinhole ring current collector and a positive electrode sheet with a high liquid absorption rate using the current collector ring.

[0008] In the first aspect, the present invention discloses a pinhole ring current collector, which adopts the following technical solution:

[0009] A pinhole ring current collector and a positive electrode plate with high liquid absorption rate using the current collector ring, comprising: a substrate and a ring extending upward toward the periphery of the substrate, the substrate is provided with a liquid absorption hole and a plurality of pinhole holes arranged in a ring around the liquid absorption hole, and the pinhole holes are protruding toward one side of the extension direction of the ring.

[0010] Preferably, the liquid suction hole and the substrate are coaxially located.

[0011] Preferably, adjacent pinhole holes are radially staggered around the liquid suction hole.

[0012] Preferably, the ratio of the diameter of the liquid suction hole to the diameter of the substrate is (2±0.05~11±0.05):(15.9±0.05).

[0013] Preferably, the ratio of the diameter of a single pinhole to the diameter of the substrate is (0.8±0.05~1.0±0.05):(15.9±0.05).

[0014] Preferably, the ratio of the spacing between adjacent pinhole holes to the diameter of the substrate is (1.0-1.5): (15.9±0.05).

[0015] Preferably, the ratio of the height of the pinhole protrusion to the diameter of the substrate is (0.75-0.85): (15.9±0.05).

[0016] Preferably, the ratio of the height of the ring to the diameter of the substrate is (1.45±0.05):(15.9±0.05).

[0017] In a second aspect, the present invention discloses a positive electrode sheet with a high liquid absorption rate using the collector ring, which adopts the following technical solution:

[0018] A positive electrode sheet with a high liquid absorption rate comprises the pinhole ring current collector, wherein the substrate and the ring of the pinhole ring current collector form a receiving cavity, wherein the receiving cavity contains positive electrode powder and electrolyte, wherein the positive electrode powder is at least partially exposed in the liquid absorption hole, and the pinhole hole protrusion penetrates into the positive electrode powder.

[0019] In a third aspect, the present invention discloses a button battery, which adopts the following technical solution:

[0020] A button battery comprises a positive electrode cover, a pinhole ring current collector, a diaphragm, a negative electrode sheet and a negative electrode cover stacked in sequence, wherein the substrate and the ring of the pinhole ring current collector form a receiving cavity, wherein the receiving cavity contains positive electrode powder and electrolyte, wherein the positive electrode powder is at least partially exposed in the liquid absorption hole, and the pinhole hole protrusion penetrates into the positive electrode powder.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] Aiming at the problem that the discharge time of the commonly used lithium-manganese dioxide button battery is short under the 10mA high current pulse mode and the discharge capacity cannot meet the use requirements of users, the present invention proposes a novel pinhole ring current collector structure design, which ensures the conductivity while quickly improving the liquid absorption rate of the positive electrode within the same soaking time by arranging a liquid absorption hole and a plurality of pinhole holes distributed in a ring shape, so that during the discharge process, the internal resistance of the battery will not increase too quickly due to insufficient electrolyte, thereby improving the capacity and capacity release rate of the battery at the same time, and solving the problem that the discharge time of the traditional button battery is short and the capacity release is low under the 10mA high current pulse. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a traditional mesh current collector and positive electrode sheet in the prior art;

[0024] Figure 2 It is a traditional bowl-shaped current collector and positive electrode sheet in the prior art;

[0025] Figure 3 This is a physical picture of the pinhole ring current collector and the positive electrode sheet of Example 1 of the present invention;

[0026] Figure 4 This is a trend chart of liquid absorption rate of the traditional bowl-shaped current collector positive electrode and the new pinhole ring current collector positive electrode;

[0027] Figure 5 This is a real picture of the through-hole ring current collector and the positive electrode sheet without pinholes;

[0028] Figure 6 It is a liquid absorption rate curve diagram of the positive electrode with a pinhole collector ring and the positive electrode without a pinhole collector ring;

[0029] Figure 7 The 3kOhm discharge curve of CR2032 battery with and without pinholes;

[0030] Figure 8 The collector ring structure of four optional embodiments has different sizes and positions of the liquid suction holes;

[0031] Fig. 9 A front view of a pinhole ring current collector structure according to another embodiment of the present invention;

[0032] Fig.10 for Fig. 9 Side view of.

[0033] Description of Figure Numbers:

[0034] 1. Substrate; 11. Liquid absorption hole; 12. Pinhole; 2. Ring; 3. Positive electrode powder. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Example 1

[0037] A pinhole ring current collector and a positive electrode sheet and a button battery with high liquid absorption rate using the current collector ring.

[0038] The eyelet ring current collector comprises a substrate 1 and a ring 2 extending upward from the periphery of the substrate 1, a liquid suction hole 11 and a plurality of eyelet holes 12 arranged in a ring around the liquid suction hole 11 are provided on the substrate 1, the eyelet holes 12 protrude toward one side of the extending direction of the ring 2, the liquid suction hole 11 and the substrate 1 are coaxially located, and adjacent eyelet holes 12 of the eyelet ring current collector are staggered radially in the liquid suction hole 11. Among them, the diameter of the substrate of the eyelet ring current collector is 15.9±0.05mm, the height of the ring is 1.45±0.05mm, the diameter of the liquid suction hole is 10±0.05mm, the diameter of a single eyelet hole is 0.8±0.05mm, the height of the eyelet hole protrusion is 0.75-0.85mm, the spacing between adjacent eyelet holes is 1.0-1.5mm, and the radial distance from each eyelet hole to the liquid suction hole is 0.8-3mm.

[0039] The positive electrode sheet includes the above-mentioned pinhole ring current collector, the substrate 1 and the ring 2 of the pinhole ring current collector form a receiving cavity, the receiving cavity contains positive electrode powder 3 and electrolyte, the positive electrode powder 3 is at least partially exposed in the liquid absorption hole 11, and the pinhole hole 12 protrudes into the positive electrode powder.

[0040] The button cell comprises a positive electrode cover, the above-mentioned pinhole ring current collector positive electrode sheet, a separator, a negative electrode sheet and a negative electrode cover which are stacked in sequence.

[0041] The production process of the button battery of Example 1 comprises the following steps:

[0042] (1) preparing positive electrode powder according to the existing process;

[0043] (2) Take the positive electrode powder produced in the production line and cut it into sheets of pinhole ring current collector positive electrode, and control the powder weight to 1.05g;

[0044] (3) After the pinhole ring current collector positive electrode is baked and cooled to room temperature, the pinhole ring current collector positive electrode is soaked in electrolyte and the electrolyte absorption rate is tested in a dry room. The data values ​​are recorded. The results are shown in Table 1.

[0045] (4) The needle-eye ring current collector positive electrode after soaking was used for the assembly and production of CR2032 lithium manganese button batteries. In the battery assembly, the lithium dosage was designed to be 225mAh. The 10mA high current pulse discharge results are shown in Table 2.

[0046] Comparative Example 1

[0047] A mesh current collector and a positive electrode sheet and a button battery using the current collector.

[0048] The mesh current collector and positive electrode sheet structure of Comparative Example 1 are shown in Figure 1 The production process of the button battery includes the following steps:

[0049] (1) preparing positive electrode powder according to the existing process;

[0050] (2) Take the positive electrode powder produced in the production line to make sheets of the mesh current collector positive electrode, and control the powder weight to 1.05g;

[0051] (3) After the mesh current collector positive electrode is baked and cooled to room temperature, the mesh current collector positive electrode is soaked in electrolyte for the same soaking time as in Example 1. The electrolyte absorption rate is tested in a drying room and the data values ​​are recorded. The results are shown in Table 1.

[0052] (4) The net-shaped current collector positive electrode after soaking was used for assembling and producing CR2032 lithium manganese button battery. In the battery assembly, the lithium dosage was designed to be 225mAh. The 10mA high current pulse discharge results are shown in Table 2.

[0053] Comparative Example 2

[0054] A bowl-shaped current collector and a positive electrode sheet and a button battery using the current collector.

[0055] The bowl-shaped current collector and positive electrode sheet of Comparative Example 2 are shown in FIG. Figure 2 The production process of the button battery includes the following steps:

[0056] (1) preparing positive electrode powder according to the existing process;

[0057] (2) Take the positive electrode powder produced in the production line and cut it into sheets of bowl-shaped current collector positive electrode, and control the powder weight to 1.05g;

[0058] (3) After the bowl-shaped current collector positive electrode is baked and cooled to room temperature, the bowl-shaped current collector positive electrode is soaked in electrolyte for the same soaking time as in Example 1. The electrolyte absorption rate is tested in a drying room and the data values ​​are recorded. The results are shown in Table 1.

[0059] (4) The bowl-shaped current collector positive electrode after soaking was used for assembling and producing CR2032 lithium manganese button battery. In the battery assembly, the lithium dosage was designed to be 225mAh. The 10mA high current pulse discharge results are shown in Table 2.

[0060] Table 1 Positive electrode liquid absorption rate

[0061]

[0062] Table 2 10mA high current pulse discharge capacity release (225mAh design)

[0063]

[0064]

[0065] Compare the test results of each group in Table 1, Table 2 and Figure 4 It can be seen that under the same positive electrode powder formula, the positive electrode prepared by using the pinhole ring current collector of the present invention has the highest liquid absorption rate. At the same time, during high current 10mA pulse discharge, the capacity release rate of the traditional mesh positive electrode button battery is only about 60%, the bowl-shaped ring current collector positive electrode button battery is better, which can reach about 75%, and the pinhole ring current collector positive electrode button battery of the present invention has the largest capacity release rate, both reaching more than 96%. The novel pinhole ring current collector positive electrode design of the present invention ensures that the internal resistance of the button battery can be carried out at a lower level during the entire discharge process by increasing the liquid absorption rate of the positive electrode, thereby improving the problem of short discharge time and low capacity release under 10mA high current pulse.

[0066] The middle liquid absorption hole and the annular pinhole hole provided in the scheme of the present invention play a synergistic role. Theoretically, if there is no large hole structure in the middle (omnidirectional pinhole), the internal contact of the positive electrode will be improved, and the current collecting effect of the ring will also increase. However, this is not the case in reality. The positive electrode sheet of the pinhole ring of the present invention and the omnidirectional pinhole are compared through experiments. Figure 2The resistance of the bowl-shaped current collector positive electrode sheet is measured with one end of the test probe at the bottom positive electrode powder and the other end at the positive electrode metal collector ring. There is no difference between the two. This is because a considerable proportion of conductive carbon material exists in the positive electrode powder formula, and the collector ring is designed to collect synergistic current and the high expansion mechanism of discharge. Therefore, the concept of the present invention is to combine the design principles of the traditional net positive current collector and the traditional bowl-shaped current collector to propose the solution of the present invention.

[0067] In order to better illustrate the synergistic effect between the middle liquid absorption hole and the annular pinhole hole of the pinhole ring current collector of the present invention, the following parallel comparative experiments are conducted to explore and verify the differences:

[0068] 1. Investigate the effect of collector ring with or without pinholes on the performance of the positive electrode

[0069] Figure 3 This is a real picture of the collector ring with pinhole holes and the positive electrode sheet after the positive electrode powder is sliced. Figure 5 The following are the actual pictures of the collector ring without pinholes and the positive electrode sheet after the positive electrode powder is punched. Except for the pinholes, the other dimensional design parameters, positive electrode powder amount, washing time and other processes of the two positive electrode sheets are the same. Figure 6 , the comparison of the discharge curves of two CR2032 button batteries with and without pinholes at 3kOhm is shown in Figure 7 .

[0070] Depend on Figure 6 and Figure 7 It can be seen that by adding the pinhole, in addition to increasing the amount of liquid absorbed by the electrolyte, the conductivity is also improved, there is a higher discharge platform in the middle of the discharge, and the potential at the end of the discharge is always high, thereby improving the utilization rate of the negative electrode and increasing the capacity of the battery. It can be seen that if only the liquid absorption hole is designed without the support of the pinhole, the liquid absorption effect will be greatly reduced, and the conductivity will also be significantly reduced. Therefore, a design balance between the pinhole and the liquid absorption hole is required to achieve the best effect.

[0071] 2. Explore the influence of the area and layout of the liquid absorption hole on the positive electrode performance

[0072] by Figure 3 The shape of the middle liquid absorption hole and the annular pinhole is taken as the benchmark (substrate diameter 15.9mm, liquid absorption hole diameter 10mm). When the liquid absorption hole diameter decreases by 1mm, the liquid absorption rate also decreases accordingly. When the liquid absorption hole diameter continues to increase, the effect of the pinhole hole is not good, and there is a large fluctuation in adverse performance. The specific test results are shown in Table 3 below.

[0073] Table 3 Distribution of positive electrode liquid absorption rate with different positive electrode ring liquid absorption hole diameters and discharge capacity release of the corresponding assembled battery under 3kOhm load

[0074]

[0075]

[0076] It can be seen from Table 3 that the larger the size of the liquid absorption hole of the current collector structure of the above optional embodiments, the higher the liquid absorption rate of the positive electrode, and the higher the battery capacity release rate. However, if the size of the liquid absorption hole exceeds a certain value, even if a liquid absorption hole is added on the basis of the current collector with a pinhole hole, the effect is even worse than not having a liquid absorption hole. This is because the protrusion of the pinhole hole requires a certain design height (0.75mm~0.85mm). If the liquid absorption hole is too large, it will affect the contact current collection effect of the pinhole hole penetrating the positive electrode. For the size of the lithium manganese button battery with a model of CR2032, the diameter of the liquid absorption hole is most preferably 10mm, and the current collection capacity and liquid absorption rate are ideally balanced at this time.

[0077] See Figure 8 The collector ring structures of four optional embodiments with four different sizes and positions of the liquid suction holes are provided, wherein: Figure 8 a and Figure 8 The size of the suction holes in b is consistent but the positions are inconsistent. Figure 8 a and Figure 8 c. Figure 8 The positions of the d holes are consistent but the sizes of the liquid absorption holes are inconsistent. From the perspective of liquid absorption rate, the liquid absorption rate is: Example 1> Figure 8 a> Figure 8 b> Figure 8 c> Figure 8 d. From the discharge curve of the battery at 3kOhm, the performance order is: Example 1> Figure 8 a> Figure 8 b> Figure 8 c> Figure 8 d. In addition, when Figure 8 The order of adding pinhole holes in the ring is equivalent to that of adding pinhole holes in the ring. It can be seen that within a certain parameter design range, the battery performance is positively correlated with the liquid absorption rate. Figure 8 a and Figure 8 From the results of b, it can be seen that although the sizes of the liquid absorption holes are the same, the positions of the liquid absorption holes affect the discharge performance of the battery. This is because the discharge of the battery is a uniform lithium consumption, so the uniformity of the current collection is beneficial to the discharge performance of the battery. The position of the liquid absorption hole will not only affect the uniform distribution of the electrolyte, but also affect the coaxial annular arrangement of the pinhole hole and the positive electrode. Therefore, the position of the liquid absorption hole is preferably designed to be coaxial with the positive electrode substrate.

[0078] 3. Investigate the effect of pinhole layout on cathode performance

[0079] See Fig. 9The pinhole ring current collector positive electrode is another optional embodiment of the present invention, and the only difference from Example 1 is that the radial distances from each pinhole of the pinhole ring current collector to the liquid absorption hole are consistent, which is about 2 mm. Although the current collection effect is similar to that of Example 1, the punching of the pinhole holes has a certain influence on the structure of the substrate. The design of the pinhole ring current collector in Example 1, in which adjacent pinhole holes are staggered radially in the liquid absorption hole, is more conducive to reducing the adverse effect of the punching of the pinhole holes on the strength, thereby improving the sheeting quality of the positive electrode powder, increasing the yield rate of button battery production, and significantly improving the service life and performance stability of the battery.

[0080] Through the above series of case implementation verification, it can be seen that under the same positive electrode powder weight, the electrolyte absorption rate of the positive electrode using the pinhole ring current collector of the present invention can be increased by 30% compared with the traditional bowl-shaped current collector positive electrode, and the capacity release rate is increased by about 20%. In addition, there are special design requirements between the liquid absorption hole and the pinhole hole of the present invention, so that the current collecting capacity and the liquid absorption rate of the positive electrode can be balanced, and then the capacity and capacity release rate of the button battery can be greatly improved, solving the problem that the discharge time is short in the current pulse mode and the discharge capacity cannot meet the user's usage needs.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention. The present invention can be applied to the production of positive electrodes of lithium-manganese button batteries of all sizes by adjusting the size and specifications.

Claims

1. A pinhole ring current collector, characterized in that: The invention comprises a base sheet and a ring extending upward from the periphery of the base sheet, wherein the base sheet is provided with a liquid suction hole and a plurality of pinhole holes arranged in a ring shape around the liquid suction hole, and the pinhole holes protrude toward one side of the extending direction of the ring.

2. The eyelet ring current collector according to claim 1, characterized in that: The liquid suction hole and the substrate are coaxially located.

3. The eyelet ring current collector according to claim 1, characterized in that: Adjacent pinhole holes are radially staggered around the liquid suction hole.

4. The eyelet ring current collector according to any one of claims 1 to 3, characterized in that: The ratio of the diameter of the liquid suction hole to the diameter of the substrate is (2±0.05~11±0.05):(15.9±0.05).

5. The eyelet ring current collector according to any one of claims 1 to 3, characterized in that: The ratio of the diameter of a single pinhole to the diameter of the substrate is (0.8±0.05~1.0±0.05):(15.9±0.05).

6. The eyelet ring current collector according to any one of claims 1 to 3, characterized in that: The ratio of the spacing between adjacent pinhole holes to the diameter of the substrate is (1.0-1.5): (15.9±0.05).

7. The eyelet ring current collector according to any one of claims 1 to 3, characterized in that: The ratio of the height of the pinhole protrusion to the diameter of the substrate is (0.75-0.85): (15.9±0.05).

8. The eyelet ring current collector according to any one of claims 1 to 3, characterized in that: The ratio of the height of the ring to the diameter of the substrate is (1.45±0.05):(15.9±0.05).

9. A positive electrode sheet with high liquid absorption rate, characterized in that: It comprises the pinhole ring current collector according to any one of claims 1 to 8, wherein the substrate and the ring of the pinhole ring current collector form a receiving cavity, wherein the receiving cavity contains positive electrode powder and electrolyte, wherein the positive electrode powder is at least partially exposed to the liquid absorption hole, and the pinhole protrusion penetrates into the positive electrode powder.

10. A button battery, characterized in that: It comprises a positive electrode cover, a pinhole ring current collector according to any one of claims 1 to 8, a diaphragm, a negative electrode sheet and a negative electrode cover stacked in sequence, wherein the substrate and the ring of the pinhole ring current collector form a receiving cavity, wherein the receiving cavity contains positive electrode powder and electrolyte, wherein the positive electrode powder is at least partially exposed to the liquid absorption hole, and the pinhole protrusion penetrates into the positive electrode powder.

Images