JP2017079188A - Magnesium battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which: in a multi-cell battery in which a plurality of magnesium battery cells are connected in series in the same container, there is a case where negative electrode active material of a cell closer to a positive electrode side of the battery disappears quickly and battery life ends although negative electrode active material of other cells is still remained; this phenomenon can be prevented by sealing encapsulation of each cell, but structure is made complicated, and the battery becomes larger and costly; it is a problem to adjust time so that negative electrode active material of each cell disappears at the same time by simple method without sealing the cells.SOLUTION: Negative electrode active material (51, 41) of cells connected close to a positive electrode (62) of a magnesium battery (10) is made thicker than negative electrode active material (41, 31) of cells connected closer to a negative electrode (61) side.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a metal-air battery containing magnesium. In particular, the present invention relates to a structure that enables stable and efficient long-term current supply in a multi-cell type magnesium battery in which a plurality of battery cells are connected in series.

  A magnesium battery using a metal or the like containing magnesium as a negative electrode and an air electrode as a positive electrode has high energy density and high safety. The material magnesium is extremely abundant in resources, inexpensive and lightweight.

  However, in a magnesium battery, discharge occurs when magnesium as a negative electrode active material is eluted into the electrolyte and reacts, so that the negative electrode active material is consumed each time the discharge is performed. Therefore, the negative electrode active material disappears eventually, and the life as a battery is exhausted.

  In order to extend the life of the battery as much as possible, ideally, it is desired that the battery function can be exhibited until all of the negative electrode active material is used up. However, since the negative electrode reaction is not necessarily uniform in each part of the negative electrode active material, although the negative electrode active material is not yet fully used as a whole, only a part of the negative electrode reaction proceeds and disappears frequently. This causes a problem that the battery life is unexpectedly shortened.

  If the amount of the negative electrode active material is increased, the lifetime until disappearance can be extended, but there are problems such as an increase in the weight and manufacturing cost of the battery. For this reason, in order to prevent the negative electrode active material of the magnesium battery from being consumed as much as possible and not to disappear, various inventions such as Patent Documents 1 to 5 have been made.

Patent No. 5034014 JP2011-181382A JP2013-191481A Japanese Patent No. 5379941 JP2014-89904A

  The inventions of Patent Documents 1 to 5 are inventions for extending the life of a single magnesium battery. However, the present invention provides means for extending the battery life in a multi-cell type magnesium battery in which a plurality of magnesium battery cells are connected in series.

  A multi-cell type magnesium battery composed of a plurality of cells connected in series can generate a high voltage that cannot be obtained with a single-cell magnesium battery, and is extremely important in practical use.

  As shown in Fig. 1, a series-connected multi-cell magnesium battery can be easily configured by arranging a plurality of cells directly adjacent to each other in a single battery container, realizing a compact and low-cost magnesium battery. it can.

  However, in such a series-connected multi-cell type magnesium battery, the cells connected closer to the positive electrode side of the battery are consumed more rapidly than the cells closer to the negative electrode side of the battery. It is empirically known to cause the phenomenon to occur.

  Therefore, in the case of a magnesium battery in which the layer thickness of each negative electrode active material of the plurality of magnesium battery cells is the same, when power generation is started, the negative electrode active material is consumed quickly in the magnesium battery cell located near the positive electrode of the battery. Even when the negative electrode active material is still sufficiently remaining in other magnesium battery cells, a phenomenon occurs in which the battery cannot function. Therefore, in some magnesium battery cells, the negative electrode active material is discarded without being used, the negative electrode active material cannot be used efficiently, and the battery life cannot be fully utilized. The life must be shorter than the theoretical life. This is a problem of the series-connected multicell magnesium battery.

  Such uneven consumption of the negative electrode active material is caused by the fact that the electrolyte in the cell leaks out and contacts the electrode of another cell (liquid junction), thereby forming a local battery between the cells. It is speculated that it is caused by that.

  Therefore, this phenomenon can be prevented if each cell is completely sealed so that the electrolyte does not leak between the cells. However, in this case, in addition to the sealing mechanism, it is necessary to provide a wiring for connecting cells in series outside the cell, so that the structure in the battery becomes complicated. This causes an increase in battery size and an increase in manufacturing cost, and is a major obstacle to realizing a small-sized and low-price series-connected multicell magnesium battery.

The present invention has been made in view of the above-described problems, and the four layers of the metal layer containing magnesium serving as the negative electrode, the separator layer filled with the electrolytic solution, the activated carbon layer, and the conductor layer serving as the positive electrode are in this order. A multi-cell type magnesium battery comprising a plurality of magnesium battery cells arranged in series, and connecting the plurality of magnesium battery cells in series to form one battery, on the positive electrode side of the magnesium battery The metal layer of the connected magnesium battery cell is made thicker than the metal layer of the magnesium battery cell connected to the negative electrode side of the magnesium battery.

  According to the present invention, in a serially connected multi-cell type magnesium battery, each cell is not sealed, and the long life of the battery is prevented while preventing waste due to a difference in consumption rate of a metal such as magnesium as a negative electrode active material in the cell. Can be realized. For this reason, effects such as reduction in weight and size of the battery and reduction in manufacturing cost can be obtained.

It is an external appearance perspective view of the magnesium battery which is one Embodiment of this invention. It is sectional drawing of the magnesium battery of FIG.

  Hereinafter, the magnesium battery which is one embodiment of the present invention shown in FIGS. 1 and 2 will be described. 1 and 2, three magnesium battery cells 30, 40, and 50 are accommodated in a rectangular battery container 20. In the present embodiment, the upper surface of the battery container 20 is opened to take in air, but the upper surface may be covered as long as ventilation is possible.

  In each of the cells 30, 40, 50, magnesium layers 31, 41, 51, which are metal layers serving as negative electrodes, intermediate separator layers 32, 42, 52, activated carbon layers 33, 43, 53, and positive electrodes, respectively The conductor layers 34, 44, and 54 are arranged in this order. Separator layers 32, 42, and 52 are filled with an electrolytic solution. In FIG. 1, the part of the negative electrode terminal 61 of the battery 10 outside the battery container and the part of the positive electrode terminal 62 of the battery 10 inside the battery container are hidden behind the battery container 20 and are not shown.

  Further, the positive electrode 34 of the cell 30 is in direct contact with the negative electrode 41 of the cell 40, and the positive electrode 44 of the cell 40 is directly adjacent to and electrically in contact with the negative electrode 51 of the cell 50, whereby the cells 30, 40, 50 are It constitutes a series connection.

  Further, the negative electrode 31 of the cell 30 is connected to the negative electrode terminal 61 of the battery 10, and the positive electrode 54 of the cell 50 is connected to the positive electrode terminal 62 of the battery 10.

  With the above configuration, in each of the cells 30, 40, and 50, oxygen in the air taken in from the activated carbon layers 33, 43, and 53 is magnesium layers 31 and 41 in the electrolyte solution of the separator layers 32, 42, and 52. , 51 reacts with the magnesium ions eluted from the cell 51, thereby generating an electromotive force between the positive electrode and the negative electrode of each cell. Since the cells 30, 40 and 50 are connected in series, an electromotive force equal to the sum of the electromotive forces of the cells is generated between the positive terminal 72 and the negative terminal 71 of the battery 10.

  Here, regarding the magnesium layers 31, 41, 51 of the cells 30, 40, 50, as a feature of the present invention, the magnesium layer 31 of the cell 30 connected closest to the negative electrode terminal 61 of the battery 10 is the thinnest, and the battery The magnesium layer 51 of the cell 50 connected closest to the 10 positive terminals 62 is configured to be the thickest.

  For example, when the relative thickness of the magnesium layer 41 is 1.0, the magnesium layer 31 may be as thin as 0.8 and the magnesium layer 51 may be as thick as 1.2. .

  By changing the thicknesses of the three magnesium layers in this way, as described in “Problems to be Solved by the Invention”, the consumption of the magnesium layer 51, which is the negative electrode of the cell 50, progresses the fastest. The consumption of the magnesium layer 41 is followed by the consumption of the magnesium layer 31 of the cell 30 most slowly, but the magnesium layer of each cell can be made to disappear almost simultaneously.

  In the present embodiment, the negative electrode active material is magnesium. However, it is apparent that the present invention can be applied to a battery using a metal containing magnesium or the like as the negative electrode active material.

  The present invention is not limited to a magnesium battery having a structure in which each cell and each layer in the cell are in contact with each other as shown in this embodiment, but each layer in the cell is configured in a concentric cylindrical shape. It is obvious that the present invention can be similarly applied to a magnesium battery that is used or a magnesium battery that is not directly adjacent to each other but is connected by a conductor.

  The present invention provides a long-life magnesium battery while suppressing the weight, size, and manufacturing cost of the battery as a whole.

10 Magnesium Battery 20 Battery Container 30 Battery Cell 31 Magnesium Layer of Battery Cell 30 (Negative Electrode)
32 Separator layer 33 of battery cell 30 Activated carbon layer 34 of battery cell 30 Conductor layer (positive electrode) of battery cell 30
40 battery cell 41 magnesium layer (negative electrode) of battery cell 40
42 Separator layer 43 of battery cell 40 Activated carbon layer 44 of battery cell 40 Conductor layer (positive electrode) of battery cell 40
50 battery cell 51 magnesium layer (negative electrode) of battery cell 50
52 Separator Layer 53 of Battery Cell 50 Activated Carbon Layer 54 of Battery Cell 50 Conductor Layer (Positive Electrode) of Battery Cell 50
61 Negative terminal of battery 10 62 Positive terminal of battery 10

Claims (1)

A plurality of magnesium battery cells in which four layers of a metal layer containing magnesium as a negative electrode, a separator layer filled with an electrolyte, an activated carbon layer, and a conductor layer as a positive electrode are arranged in this order,
A multi-cell type magnesium battery in which a plurality of magnesium battery cells are connected in series to form one battery,
The metal layer of the magnesium battery cell connected to the positive electrode side of the magnesium battery is named as the metal layer of the magnesium battery cell connected to the negative electrode side of the magnesium battery. Multi-cell type magnesium battery.

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