JP5802489B2 - Alkaline battery - Google Patents

Description

  The present invention relates to an alkaline battery, and specifically to a technique for achieving both discharge performance and reliability in an alkaline battery.

  FIG. 1 shows a general structure of an alkaline battery which is an object of the present invention. The figure is an LR6 type cylindrical alkaline battery 1 and is a longitudinal sectional view when the extending direction of the cylindrical shaft 10 is a longitudinal direction. The alkaline battery 1 includes a bottomed cylindrical metal battery can (positive electrode can) 2, an annularly formed positive electrode mixture 3, and a bottomed cylindrical separator disposed inside the positive electrode mixture 3. 4. Negative electrode gel 5 filled with zinc alloy inside separator 4, negative electrode current collector 6 inserted in negative electrode gel 5, negative electrode terminal plate 7, sealing gasket 8, and positive electrode can 2 are filled It consists of an electrolyte solution.

  Specifically, the positive electrode can 2 is manufactured by pressing a Ni-plated steel plate, and is a battery case that houses a power generation element. Also functions as a current collector. A positive electrode terminal 9 is formed on the bottom surface of the positive electrode can 2.

  The positive electrode mixture 3 is a mixture of a positive electrode active material such as manganese dioxide or nickel oxyhydroxide, a conductive material (such as graphite), a binder, and an aqueous potassium hydroxide (KOH) solution that is an electrolytic solution. A powdered granulated product (mixture granule) adjusted to a predetermined particle size is produced by processes such as crushing and granulation, and the mixture granule is formed into a ring shape using a mold or the like. It is obtained by. The negative electrode gel 5 is mixed by adding a powdery zinc alloy (zinc powder) as an active material to a mixture of a gelling agent and an electrolytic solution, or adding an electrolytic solution to a mixture of zinc powder and a gelling agent. Or made.

  The negative electrode gel 5 is disposed inside the annular positive electrode mixture 3 via a bag-like separator 4 made of a bottomed cylindrical nonwoven fabric or the like, and is a rod-shaped metal negative electrode current collector inserted into the negative electrode gel 5. 6 is erected and fixed to the inner surface of the battery in the plate-shaped metal negative electrode terminal plate 7 by welding. The negative electrode terminal plate 7, the negative electrode current collector 6, and the sealing gasket 8 are combined in advance as a sealing body, and the outer periphery of the sealing gasket 8 is formed between the opening edge of the positive electrode can 2 and the peripheral edge of the negative electrode terminal plate 7. The positive electrode can 2 is hermetically sealed by being clamped in between.

  By the way, since the alkaline battery forms a high-resistance zinc oxide film on the surface of the zinc alloy constituting the negative electrode by a discharge reaction, the utilization factor of zinc as the negative electrode active material is lowered. That is, not all negative electrode active materials contribute to the discharge reaction. Therefore, in an alkaline battery, the negative electrode capacity is generally increased by about 10 to 20% with respect to the positive electrode capacity (see, for example, Patent Document 1).

  However, when the negative electrode capacity is made larger than the positive electrode capacity, unreacted zinc remains in the battery after the discharge of the alkaline battery. For example, the alkaline battery after the discharge is not taken out from the device using the battery. When left in an overdischarged state, a large amount of gas that causes leakage is generated. In Patent Documents 2 and 3 below, in order to prevent zinc from corroding and generating gas when anhydrous silver zinc is used as the negative electrode active material, the electrolytic solution is made of lithium hydroxide or the like. A technique for adding a lithium salt is described. In addition, in Patent Document 4 below, in an alkaline battery using a nickel oxyhydroxide-based positive electrode active material, a lithium salt is added to the electrolytic solution, thereby generating gas during overdischarge while maintaining discharge performance. The technology to suppress is described.

JP-A-61-54157 Japanese Patent Application Laid-Open No. 5-135576 JP 2000-36318 A JP 2007-250451 A

  From the techniques described in Patent Documents 2 to 4, it can be seen that it is useful to some extent to add a lithium salt to the electrolytic solution in order to suppress gas generation during overdischarge. However, improvement in discharge performance and suppression of gas generation during overdischarge have not been achieved at a high level. As is well known, this is probably because the solubility of the lithium salt is small, and even if the lithium salt is added to the electrolytic solution, the effect of improving the discharge performance cannot be obtained sufficiently.

  In addition, Patent Documents 2 to 4 do not have the purpose of further increasing discharge capacity by further increasing the capacity ratio of the negative electrode to the positive electrode capacity (negative electrode capacity / positive electrode capacity), and mainly suppress the generation of gas. The purpose is that. For example, in the alkaline battery described in Patent Document 4, the capacity ratio is set to 0.85 to 1.05, which is lower than the capacity ratio in the alkaline battery described in Patent Document 1.

  In view of this, the present invention suppresses the generation of gas during overdischarge to prevent leakage even when the capacity ratio of the negative electrode to the positive electrode capacity is increased in order to improve the discharge performance. It is intended to provide.

In order to achieve the above object, the present invention provides a positive electrode mixture formed in a ring shape containing MnO ₂ as a positive electrode active material, and a negative electrode gel containing a zinc alloy as a negative electrode active material in a hollow portion of the positive electrode mixture. An alkaline battery arranged via
LiOH is added to the positive electrode mixture in an amount of 1.0 mmol / Ah to 10.0 mmol / Ah with respect to the theoretical capacity of the positive electrode,
The ratio of the theoretical capacity of the negative electrode to the theoretical capacity of the positive electrode (theoretical capacity of the negative electrode / theoretical capacity of the positive electrode) is 1.2 or more and 1.3 or less,
The alkaline battery is characterized by this.

Alternatively, an alkaline battery in which a positive electrode mixture formed into a ring shape containing MnO ₂ as a positive electrode active material and a negative electrode gel containing a zinc alloy as a negative electrode active material in a hollow portion of the positive electrode mixture is disposed via a separator. Because
LiOH is added to the negative electrode gel in an amount of 0.8 mmol / Ah or more and 8.0 mmol / Ah or less with respect to the theoretical capacity of the negative electrode,
The ratio of the theoretical capacity of the negative electrode to the theoretical capacity of the positive electrode (theoretical capacity of the negative electrode / theoretical capacity of the positive electrode) is 1.2 or more and 1.3 or less,
The alkaline battery is characterized by this.

  According to the alkaline battery of the present invention, the ratio of the negative electrode capacity to the positive electrode capacity can be increased, the discharge performance can be improved, and gas generation is suppressed even in an overdischarged state, thereby reliably preventing liquid leakage. Can be prevented and high reliability can be ensured.

It is a figure which shows the structure of an alkaline battery.

  The structure of the alkaline battery according to the embodiment of the present invention is the same as that of the general alkaline battery 1 shown in FIG. However, it differs from the conventional alkaline battery in that a lithium salt is added to at least one of the positive electrode mixture or the negative electrode gel. Then, in order to compare the performance of the alkaline battery and the conventional alkaline battery in this example, the presence or absence of the addition of lithium salt to the positive electrode mixture or the negative electrode gel, the addition amount of lithium salt, and the negative electrode capacity relative to the positive electrode capacity Various types of LR6 type alkaline batteries with different ratios were produced as samples, and the performance of each sample was evaluated.

=== Sample manufacturing conditions ===
Each sample was produced under the same conditions except for the positive electrode mixture or the presence / absence of addition of lithium salt to the negative electrode gel, the addition amount, and the ratio of the negative electrode capacity to the positive electrode capacity. The production conditions for the positive electrode mixture and the negative electrode gel are shown below.

  The positive electrode mixture 3 was granulated by using electrolytic manganese dioxide (EMD) as a positive electrode active material and mixing the positive electrode active material with graphite as a conductive material, polyacrylic acid as a binder, and an aqueous KOH solution as an electrolytic solution. This is a product that is press-molded in an annular shape. Depending on the sample, lithium hydroxide (LiOH) is added as a lithium salt in a predetermined amount with respect to the theoretical capacity of the positive electrode depending on the conditions of the sample.

  The negative electrode gel 5 is a mixture of zinc powder, polyacrylic acid as a gelling agent, and a KOH aqueous solution. In addition, with respect to the negative electrode gel 5, depending on the sample, LiOH is added in a predetermined amount with respect to the negative electrode theoretical capacity according to the conditions of the sample. The power generation element including the positive electrode mixture 3 and the negative electrode gel 5 produced in the above-described manner under different conditions is housed in the positive electrode can 2, and the opening of the positive electrode can 2 is hermetically sealed. Various types of samples (s1 to s23) were prepared.

Table 1 shows the production conditions for each sample.

  In Table 1, s1 to s5 are samples corresponding to a conventional alkaline battery in which LiOH is not added to either the positive electrode mixture or the negative electrode gel. Samples s6 to s23 are alkaline batteries in which LiOH is added to any one of the positive electrode mixture and the negative electrode gel, and the addition target of the LiOH (positive electrode mixture, negative electrode gel), the addition amount, the theoretical capacity ratio, and the like. Is different.

=== Discharge performance test, leak test ===
The samples s1 to s23 shown in Table 1 were subjected to a discharge performance test and a liquid leakage test. The discharge performance test was carried out by discharging for 1 hour a day with a load of 10Ω and measuring the cumulative time until a final voltage of 0.9V was reached. In addition, the discharge performance of each sample was evaluated by a relative value when a predetermined cumulative time was 100. Further, in the liquid leakage test, each sample was continuously discharged for 48 hours under a load of 10Ω in order to reproduce the overdischarge state, and the presence or absence of liquid leakage was visually confirmed after the completion of the continuous discharge.

<Conventional alkaline battery>
In order to confirm the effect of adding LiOH to the positive electrode mixture or the negative electrode gel, first, a discharge performance test and a liquid leakage test were performed on samples s1 to s5 that are alkaline batteries having a conventional configuration to which no LiOH was added. It was.

Table 2 below shows the test results of the samples s1 to s5.

  In Tables 3 and 4 including Table 2, as a result of the leakage test, the case where there was no leakage was indicated by “◯”, and the case where leakage occurred was indicated by “X”. From the results shown in Table 2, it was confirmed that the discharge performance was improved by increasing the ratio of the negative electrode theoretical capacity to the positive electrode theoretical capacity (hereinafter, the theoretical capacity ratio). However, liquid leakage occurred in samples s2 to s5 having a theoretical capacity ratio of 1.20 or more. In other words, it was found that the discharge performance cannot be improved by simply increasing the theoretical capacity ratio in practice. Therefore, among the samples s1 to s5 of the conventional configuration, the discharge performance of the sample s1 in which no leakage occurred is used as a reference for all the other samples s2 to s23, and the relative discharge when the discharge performance of the sample s1 is 100. The discharge performance of each of the other samples s2 to s23 was evaluated by the value. Hereinafter, the sample s1 is referred to as a reference battery s1.

<Addition amount of LiOH>
Regarding samples s6 to s23 in which LiOH is added to either the positive electrode mixture or the negative electrode gel, first, whether or not the discharge performance can be improved by adding LiOH according to samples s6 to s15 in Table 1 Evaluated. That is, in the alkaline battery of the conventional configuration, the theoretical capacity ratio was 1.19 of the reference battery, which was the upper limit. However, whether the generation of liquid leakage can be prevented by suppressing the generation of gas even when the upper limit is exceeded. evaluated.

Table 3 shows the test results of samples s6 to s15.

  Table 3 shows the test results for samples s6 to s10 in which LiOH is added to the positive electrode mixture with different addition amounts, and samples s11 to s15 to which LiOH is added in the negative electrode gel with different addition amounts. . In samples s6 to s15, the theoretical capacity ratio is increased by 25% with respect to the reference battery s1. As a result, no leakage occurred in samples s7 to s10 in which LiOH was added to the positive electrode mixture in an amount of 1.0 mmol or more per theoretical capacity of the positive electrode mixture. Further, in sample s10 in which the addition amount of LiOH was 11.0 mmol / Ah, the discharge performance was equivalent to that of reference battery s1.

  In samples s11 to s15 in which LiOH was added to the negative electrode gel, no leakage occurred in samples s12 to s15 in which the amount of LiOH added was 0.8 mmol or more per theoretical capacity of the negative electrode gel. Further, in sample s15 in which the amount of LiOH added was 9.0 mmol / Ah, the discharge performance was equivalent to that of reference battery s1.

  The above test results in s6 to s15 show that the effect of suppressing gas generation is reduced when the amount of LiOH added is small, and that the amount of LiOH is relatively large with respect to the capacity of the positive electrode or the negative electrode and the discharge performance is hindered. , Suggests that. And the optimal addition amount range of LiOH with respect to positive electrode mixture is 1.0 mmol / Ah or more and 10.0 mmol / Ah or less, and the optimal addition amount range of LiOH with respect to negative electrode gel is 0.8 mmol / Ah or more, and 8. It was found that it was 0 mmol / Ah or less. Even when the amount is less than the optimum addition amount range, the samples s6 and s11 have a theoretical capacity ratio increased by 25% from the reference battery s1, and considering this fact, the theoretical capacity ratio is the reference battery s1. It can be easily predicted that it can be larger than 1.19. In addition, the samples s10 and s15 having the optimum addition amount range or more maintain discharge performance equivalent to that of the reference battery s1, and the alkaline battery is placed in an overdischarged state in consideration of the environment and the situation in which the battery is used. When it is desired to ensure the reliability at the time of discharge, a slight decrease in discharge performance may be allowed. That is, if LiOH is added to the positive electrode mixture or the negative electrode mixture, it can be expected that at least one of the performances of improving the discharge performance and preventing the occurrence of liquid leakage is maintained and the other effect is obtained. And the said optimal addition amount range is the conditions for making the improvement of discharge performance and generation | occurrence | production prevention of a leak compatible at a high level.

<Optimization of theoretical capacity ratio>
It was confirmed that the discharge performance was improved and the leakage was prevented by adding LiOH to the positive electrode mixture and the negative electrode gel. It was also confirmed that there was an optimal numerical range for the amount of LiOH added. Therefore, the optimum numerical range of the theoretical capacity ratio was also examined. In the examination, first, samples with various theoretical capacity ratios changed while adopting the median value of the optimum addition amount range obtained from the results of Table 3 above as the addition amount of LiOH to the positive electrode mixture and the negative electrode gel. About s16-s23, s8, and s14, the discharge performance test and the liquid leakage test were done.

Table 4 shows the test results of samples s16 to s23, s8, and s14.

  Samples s16 to s19 and s8 were samples in which LiOH was added to the positive electrode mixture, and leakage occurred in sample s19 having a theoretical capacity ratio of greater than 1.30. Further, in the sample s16 in which the theoretical capacity ratio is 1.19 which is the same as that of the reference battery s1, the discharge performance is the same as that of the reference battery s1. Similarly, in the samples s20 to s23 and s14 in which LiOH is added to the negative electrode gel, liquid leakage occurs in the sample s23 having a theoretical capacity ratio of greater than 1.30, and the theoretical capacity ratio is the same as that of the reference battery s1. Then, the discharge performance became the same as that of the reference battery s1.

  From the above, it can be seen that in the alkaline battery in which LiOH is added to the positive electrode mixture or the negative electrode gel, there is an optimum numerical range in the theoretical capacity ratio, and the numerical range is from 1.2 to 1.3. It was. The optimum numerical range of this theoretical capacity ratio is relative to the median value of the optimum addition amount range of LiOH, and if the lower limit or upper limit of the optimum addition amount range is adopted, the optimum numerical range of the theoretical capacity ratio is It seems to expand further. It can be said that the optimum numerical range of the theoretical capacity ratio obtained from Table 4 is a condition for achieving both higher discharge performance and prevention of leakage at a higher level.

  As a matter of course, the effect of adding LiOH is that the addition target is expressed separately in the positive electrode mixture and the negative electrode gel, and even if LiOH is added to both the positive electrode mixture and the negative electrode gel. , Performance will not be offset. In addition, since the generation of gas causing leakage is mainly derived from the zinc of the negative electrode, the positive electrode active material can be a mixture of manganese dioxide and nickel oxyhydroxide, or oxywater can be used instead of manganese dioxide. Even if nickel oxide is used, if LiOH is added to the positive electrode mixture containing the positive electrode active material, it is expected that the discharge capacity can be improved by increasing the theoretical capacity ratio while preventing leakage.

  The alkaline battery according to the present invention is suitable, for example, for an electronic device (such as a remote control device for home appliances) that is frequently used on a daily basis while being mounted over a long period of time.

1 alkaline battery, 2 battery can (positive electrode can), 3 positive electrode mixture, 4 separator,
5 Negative gel, 6 Negative current collector, 7 Negative terminal plate, 8 Gasket, 9 Positive terminal

Claims (2)

An alkaline battery in which a positive electrode mixture formed into a ring shape containing MnO ₂ as a positive electrode active material and a negative electrode gel containing a zinc alloy as a negative electrode active material in a hollow portion of the positive electrode mixture are arranged via a separator. And
LiOH is added to the positive electrode mixture in an amount of 1.0 mmol / Ah to 10.0 mmol / Ah with respect to the theoretical capacity of the positive electrode,
The ratio of the theoretical capacity of the negative electrode to the theoretical capacity of the positive electrode (theoretical capacity of the negative electrode / theoretical capacity of the positive electrode) is 1.2 or more and 1.3 or less,
An alkaline battery characterized by that. An alkaline battery in which a positive electrode mixture formed into a ring shape containing MnO ₂ as a positive electrode active material and a negative electrode gel containing a zinc alloy as a negative electrode active material in a hollow portion of the positive electrode mixture are arranged via a separator. And
LiOH is added to the negative electrode gel in an amount of 0.8 mmol / Ah or more and 8.0 mmol / Ah or less with respect to the theoretical capacity of the negative electrode,
The ratio of the theoretical capacity of the negative electrode to the theoretical capacity of the positive electrode (theoretical capacity of the negative electrode / theoretical capacity of the positive electrode) is 1.2 or more and 1.3 or less,
An alkaline battery characterized by that.

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