JP2019197613A - Bobbin-type lithium primary battery - Google Patents

Abstract

To provide means for eliminating variance in battery characteristics by suppressing dispersion of an electrolyte that is accommodated inside of a battery, at the time of sealing and to provide a method for suppressing lithium exhaustion on a last stage of charging.SOLUTION: The present invention relates to a bobbin type lithium primary battery in which a positive electrode mixture in a hollow cylinder shape and a negative electrode lithium disposed inside of the positive electrode mixture via a separator are accommodated together with an electrolyte within a battery can in an upwardly opened bottomed cylinder shape, and which is configured by sealing the opening of the battery can with a sealing body. The bobbin type lithium primary battery is characterized in that multiple positive electrode mixtures are stacked while having a clearance therebetween so as to be coaxial in a vertical direction and for the negative electrode lithium, a lithium metal or a lithium alloy is molded in a hollow cylinder shape. A negative electrode collector consisting of a metallic thin plate is attached onto an inner surface of the negative electrode lithium in the hollow cylinder shape, and a lower end of the negative electrode collector faces a region of the clearance of the positive electrode mixtures.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bobbin-type lithium primary battery.

  The bobbin-type lithium primary battery has a feature that it uses lithium metal or a lithium alloy as a negative electrode active material and has high energy density and high capacity. For this reason, it is widely used for applications that continue to be used without maintenance for a long period of time, such as batteries for memory backup of various measuring instruments and electronic devices.

  A general bobbin-type lithium primary battery has a hollow cylindrical positive electrode mixture and a hollow cylindrical positive electrode mixture, and a separator inside the positive electrode mixture. Negative electrode lithium is accommodated together with the electrolytic solution, and the opening of the battery can is sealed by a sealing body (for example, Patent Documents 1 and 2).

  The material of the positive electrode mixture is not particularly limited as long as it is a substance usually used in a bobbin-type lithium primary battery. For example, manganese dioxide or the like can be used as the positive electrode active material. In addition, a conductive aid such as a carbon material can be used as appropriate.

  In the negative electrode lithium, a plate-like lithium metal or lithium alloy is formed into a hollow cylindrical shape, and a negative electrode current collector made of a thin metal plate is attached to the inner surface of the hollow cylindrical negative electrode lithium. The negative electrode current collector is made of a strip or rectangular thin metal plate, and one end of the negative electrode current collector is bonded to the inner surface side of the hollow cylindrical negative electrode lithium.

  Here, since the amount of the electrolyte solution accommodated in the battery affects the characteristics at the end of discharge, it is preferable that the amount is as large as possible. However, when sealing the battery, there is a possibility that the amount of the electrolytic solution is scattered, which is one of the causes of variation in battery characteristics.

  In addition, at the end of discharge, there is a problem that the capacity of the battery cannot be used due to the fact that lithium is cut off at the edge portion of the peripheral edge of the negative electrode current collector and the voltage drops rapidly.

JP 2009-48913 JP-A-2006-58220

  Therefore, an object of the present invention is to provide a means for preventing the electrolyte contained in the battery from scattering at the time of sealing and eliminating the variation in battery characteristics. It is another object of the present invention to provide a means for suppressing lithium shortage at the end of discharge.

  One aspect of the present invention for achieving the above object is to provide a hollow cylindrical positive electrode mixture in a bottomed cylindrical battery can opened upward and a separator inside the positive electrode mixture. Is a bobbin-type lithium primary battery in which an opening of the battery can is sealed with a sealing body, and a plurality of the positive electrode mixtures are coaxial in the vertical direction. The negative electrode lithium is formed by forming a plate-like lithium metal or lithium alloy into a hollow cylindrical shape, and forming a negative electrode assembly made of a thin metal plate on the inner surface of the hollow cylindrical negative electrode lithium. The bobbin type lithium primary battery is characterized in that an electric body is attached, and the negative electrode current collector has a lower end facing the gap region of the positive electrode mixture.

  Further, the present invention is characterized in that the lower end of the negative electrode current collector exists in the gap between the positive electrode mixture located in the lowermost layer and the positive electrode mixture located in the layer above it. The present invention also extends to the bobbin-type lithium primary battery, wherein the bobbin-type lithium primary battery is provided with a liquid-absorbing spacer in the gap.

  According to the present invention in which there is a gap between the positive electrode mixture, when the same amount of the electrolytic solution as in the prior art in which there is no gap between the positive electrode mixture is put, the height of the liquid level becomes low and the scattering of the electrolytic solution is prevented. Can be deterred. As a result, the amount of the electrolyte solution in the battery increases and the variation decreases, so that the battery characteristics at the end of discharge become more stable.

  Further, by causing the lower end of the negative electrode current collector to face the gap region of the positive electrode mixture, it is possible to suppress lithium breakage, which also contributes to the stability of battery characteristics.

It is a figure which shows the structure of the bobbin type lithium primary battery which concerns on this invention. It is a figure which shows the structure of the bobbin type lithium primary battery which concerns on this invention. It is a figure which shows the structure of the bobbin type lithium primary battery which concerns on a prior art.

  Hereinafter, although embodiment of this invention is described, the range of this invention is not limited to the said description including an Example.

  The bobbin-type lithium primary battery according to the present invention is characterized in that a plurality of hollow cylindrical positive electrode mixtures are stacked with a gap therebetween so as to be coaxial in the vertical direction.

  It is considered that the scattering of the electrolytic solution at the time of sealing the battery, which was a problem, is caused by the height of the liquid surface of the electrolytic solution. In the present invention, as one means for lowering the liquid level, a gap is provided between the positive electrode mixture.

  Here, the present invention will be described using a cross-sectional view of a bobbin-type lithium primary battery.

  FIG. 1 is a cross-sectional view of a bobbin-type lithium primary battery 1 according to this embodiment. A plurality of hollow cylindrical positive electrode mixtures 2 are held in a bottomed cylindrical battery can 7 that opens upward, and a negative electrode lithium 4 is accommodated together with an electrolyte (not shown) via a separator 8 inside thereof. Has been. The opening of the battery can 7 is sealed by a sealing body 10. Specifically, the sealing body 10 includes a metal negative electrode terminal plate 11 and a sealing plate 12. Reference numeral 9 denotes a positive terminal portion. In the present invention, the positive electrode mixture 2 is laminated with a gap 3 therebetween so as to be coaxial in the vertical direction. Further, the negative electrode lithium 4 is a plate-shaped lithium metal or lithium alloy formed into a hollow cylinder, and a negative electrode current collector 5 made of a thin metal plate is attached to the inner surface of the negative electrode lithium 4. The negative electrode current collector 5 has a lower end 6 facing the region of the gap 3 between the positive electrode mixture.

  FIG. 2 is a cross-sectional view of a bobbin-type lithium primary battery 20 obtained by rotating the bobbin-type lithium primary battery 1 according to FIG. 1 by 90 degrees along the vertical axis. In addition, the code | symbol of the components including positive electrode mixture is the same as that of FIG.

  FIG. 3 is a cross-sectional view of a bobbin-type lithium primary battery 100 according to the prior art. 1, the positive electrode mixture 2 is 102, the negative electrode lithium 4 is 104, the negative electrode current collector 5 is 105, the battery can 7 is 107, the separator 8 is 108, the positive electrode terminal portion 9 is 109, the sealing body 10, and a metal negative electrode The terminal plate 11 and the sealing plate 12 correspond to 110, 111, and 112, respectively. That is, the conventional bobbin-type lithium primary battery 100 illustrated in FIG. 3 does not have the gap 3 in FIG.

  When a gap is provided between the positive electrode mixture as in this embodiment, the bottom surface or top surface of the positive electrode mixture also contributes to water absorption of the electrolyte solution in addition to the inner circle portion of the positive electrode mixture. The liquid absorption speed of the electrolyte is improved. On the other hand, as in the prior art (for example, Patent Document 1 and Patent Document 2), when the positive electrode mixture is packed and pressed into the battery can without providing a gap between the positive electrode mixtures, the electrolyte is absorbed. The part to do stays in the inner circle part of the positive electrode mixture.

  That is, when the time from when the electrolytic solution is put into the battery to sealing (aging time) is the same, the liquid level is lower than when no gap is provided between the positive electrode mixture. Can be prevented. As a result, the appearance of the electrolyte depleted state at the end of discharge can be further delayed, and more stable battery characteristics can be obtained.

  Further, the same effect can be expected by providing a spacer having liquid absorbency in the gap 3. As the liquid-absorbing spacer, for example, a separator may be used.

  Furthermore, as one of the causes of the sudden drop of the voltage at the end of discharge, there is a so-called negative electrode lithium shortage as described above. Specifically, the negative electrode lithium shortage occurs from the lower end. Here, in the portion facing the gap 3 between the positive electrode mixture 2, the negative electrode lithium 4 hardly reacts. By paying attention to this, the reaction of lithium can be suppressed by making the lower end portion of the negative electrode current collector 5 face the region of the gap 3 of the positive electrode mixture 2. Then, since lithium at the lower end expands with time, it is possible to extend the time during which the negative electrode lithium is cut off, and to obtain more stable battery characteristics.

  In order to increase the contact area between the negative electrode lithium 4 and the negative electrode current collector 5, the lower end 6 of the negative electrode current collector 5 is positioned in the positive electrode mixture 2 positioned in the lowermost layer and the layer one above it. It is preferably present in the gap 3 with the positive electrode mixture 2.

  Here, the dimension of the gap 3 between the positive electrode mixture 2 can be adjusted as appropriate by those skilled in the art in order to obtain the above effect satisfactorily. However, if the gap 3 is excessively widened, the reactivity of the positive electrode and the negative electrode is increased. In some cases, the battery characteristics may be uneven and the battery characteristics may vary. Moreover, since it is necessary to put a battery member in a fixed space in the design of the battery, a loss occurs in terms of capacity.

  In addition, as the binder, the solvent, and the like used when producing the bobbin-type lithium primary battery 1, known ones used in conventional bobbin-type lithium primary batteries can be used.

=== Embodiment of the Invention ===
Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention should not be limited to these examples.

<Measurement of electrolyte retention rate>
A CR17450 size battery was prepared by the following procedure.

(1) As an example, five bobbin-type lithium primary batteries having a structure equivalent to that shown in FIG. As a comparative example, five bobbin-type lithium primary batteries having a structure equivalent to that shown in FIG.
(2) After preparing 10 types of electrolytes having the same weight to be injected into the 10 batteries, the weights of the 10 batteries were measured. The total of the weight of each battery and the weight of the electrolyte is defined as “weight before sealing”.
(3) The electrolyte solution was put into each of the 10 batteries and sealed.
(4) The weight of each of the 10 batteries after the sealing was measured. The weight of each battery is referred to as “weight after sealing”.
(5) For each of the 10 batteries, the liquid retention rate in the battery of the electrolyte was measured by the following formula: (weight after sealing / weight before sealing) × 100.

  Table 1 shows the liquid retention ratio in the battery. Note that σ is a standard deviation.

  From the results in Table 1, the bobbin-type lithium primary battery according to the example in which a gap exists between the positive electrode mixtures is compared with the bobbin-type lithium primary battery in which no gap exists between the positive electrode mixtures according to the comparative example. As a result, the weight loss due to scattering of the electrolyte was small, and the standard deviation, that is, the variation was small.

<Constant resistance discharge test>
For each of the 10 batteries after the sealing, a constant resistance discharge test was further performed under the condition of 1 kΩ. Table 2 shows the discharge capacity when the filling capacity (the total theoretical capacity of the positive electrode and the negative electrode) is 100.

  From the results of Table 2, the bobbin-type lithium primary battery according to the example in which a gap exists between the positive electrode mixtures is more than the bobbin-type lithium primary battery according to the comparative example in which there is no gap between the positive electrode mixtures. Excellent discharge performance was shown.

DESCRIPTION OF SYMBOLS 1,20,100 ... Bobbin-type lithium primary battery 2,102 ... Positive electrode mixture 3 ... Gap between positive electrode mixtures 4,104 ... Negative electrode lithium 5,105 ... Negative electrode collector 6 ... Lower end of negative electrode current collector 7, 107 ... Battery can 8, 108 ... Separator 9, 109 ... Positive electrode terminal portion 10, 110 ... Sealing body 11, 111 ... Negative electrode terminal Plate 12, 112 ... Sealing plate

Claims (3)

Inside the bottomed cylindrical battery can that opens upward, the hollow cylindrical positive electrode mixture, and the negative electrode lithium disposed through the separator inside the positive electrode mixture are stored together with the electrolyte, A bobbin-type lithium primary battery in which the opening of the battery can is sealed by a sealing body,
A plurality of the positive electrode mixture is laminated with a gap so as to be coaxial in the vertical direction,
The negative electrode lithium is a plate-like lithium metal or lithium alloy formed into a hollow cylindrical shape,
A negative electrode current collector made of a thin metal plate is attached to the inner surface of the hollow cylindrical negative electrode lithium,
The bobbin-type lithium primary battery, wherein the negative electrode current collector has a lower end facing the gap region of the positive electrode mixture.   2. The bobbin according to claim 1, wherein a lower end of the negative electrode current collector exists in a gap between the positive electrode mixture located in the lowermost layer and the positive electrode mixture located in the upper layer. Lithium primary battery.   The bobbin-type lithium primary battery according to claim 1, wherein a spacer having a liquid absorbing property is provided in the gap.

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