RU2543069C2 - Tiny thermal lithium current source - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to the electric industry and can be used in production of thermal chemical lithium current sources. According to the invention along the lateral surface of the unit of electrochemical elements the ultrathin pyrotechnic heater is laid, and between anodic and pyrotechnic tablets of the unit of electrochemical elements the heat-retaining conductive disks with the diameter equal to the diameter of the unit of electrochemical elements, and with the thickness, amounting 0.25-0.35 from the thickness of the anode tablet are installed.

EFFECT: development of the tiny thermal lithium current source which is characterised by comparability of thickness and diameter of details of the unit of electrochemical elements.

1 dwg

Description

The invention relates to the electrical industry and can be used in the production of thermal chemical current sources.

The development of miniature thermal current sources is associated with the need to solve technological and thermophysical problems dictated by their small size.

Technological problems consist in providing the possibility of obtaining miniature anode, electrolyte and cathode tablets, characterized by low weight, small dimensions, chemical aggressiveness, the difficulty of switching electrical circuits and assembly work. In this case, all operations of the manufacture of parts should be carried out in a dried environment.

Thermophysical problems are associated with the need to maintain the temperature level required for operation with a sufficiently long operating time while maintaining the specific energy consumption and discharge at high current densities (≥2 A / cm ² ). The task is complicated due to heat losses that are not amenable to thermal calculations during the operation of facilities powered by thermal current sources. This is especially true for miniature current sources.

Known thermal lithium current source [JP Patent No. 2808652, class. H01M 6/36 claimed 04.24.1989, publ. 10/08/1998], containing a block of electrochemical elements placed in a housing and sealed by a lid, consisting of sequentially arranged anode, electrolyte, cathode and pyrotechnic tablets, narrow pyrotechnic strips diametrically installed on the side surface of the block transmitting a fire pulse from an ignition device located in the basis of the block of elements on pyrotechnic tablets. Thermal insulation is installed on the side surface of the block and at its ends.

The design principles used in this current source are suitable for large-sized current sources and cannot be applied in the design of miniature current sources, since even when solving technological problems, the most difficult questions remain related to ensuring and maintaining the operating temperature for a sufficiently long time .

The closest in technical essence is a thermal current source [Patent RU No. 2408113 C1, cl. H01M 6/36, 12/14/2009], containing a block of electrochemical elements placed in a housing and sealed by a lid, assembled from sequentially arranged anode, electrolyte, cathode and pyrotechnic tablets, the side surface of the block is covered with thermal insulation and surrounded by a pyrotechnic element, the ends of the block are installed thermal insulation pads.

A disadvantage of the known current source is the large overall dimensions, which does not allow it to be used to power small-sized consumers of electric energy.

The design solutions used in it are unacceptable for miniature current sources, since the pyrotechnic element, which provides the supply of additional heat to the block of electrochemical elements and thereby increases the duration of the current source, is large. In addition, it is separated from the block of electrochemical elements by thermal insulation, which also requires heat to warm up, and this thermal insulation occupies a significant amount.

The aim of the proposed technical solution is to develop a miniature thermal current source with a lithium-containing anode while maintaining the specific characteristics achieved for large current sources.

For this purpose, a miniature thermal lithium current source is proposed, comprising a block of electrochemical elements placed in a housing and sealed by a lid, assembled from sequentially arranged anode, electrolyte, cathode and pyrotechnic tablets, the side surface of the block is covered with thermal insulation and surrounded by a pyrotechnic element receiving a fire pulse from the ignition device , in the end parts of the installed heat-insulating gaskets, characterized in that the pyrotechnic element is made in the form of ultra atonkoy pyrotechnic strip tape tightly fitting the side surface of the block electrochemical cells, and between the anode pyrotechnic pill installed heat storage disks conductive diameter equal to the block thickness and electrochemical cells, 0.25-0.35 component on the thickness of the anode tablets.

In the proposed current source, in order to minimize the design, the electrochemical cells receive the heat necessary for heating to operating temperatures both from the combustion of pyrotechnic tablets installed between the electrochemical cells, and from the pyrotechnic tape strip covering the side surface of the cell block. However, to heat the electrochemical cells to operating temperatures, the heat generated by the pyrotechnic tablets is sufficient. Therefore, at the time of passing along the block of elements of the combustion front of the pyrotechnic strip strip, the temperature of the side surface of the anode will exceed its melting temperature. As a result, the active mass of the lithium anode will melt and leak onto the perimeter of the cell block, resulting in a short circuit of the electrochemical cells. The process is aggravated due to the commensurability of the thickness and diameter of the parts of the electrochemical element, because of which the burning rate of the pyrotechnic tablet in diameter of the block of elements is comparable with its heating time.

A positive effect, in terms of eliminating the melting of the anode tablet, was obtained by installing heat-accumulating conductive disks between the anode and pyrotechnic tablets. Due to the high thermal conductivity and good thermal contact with the anode due to the preloading of the block of elements, the disks instantly accumulate heat going to the anode tablet at the initial moment of operation of the current source, preventing its melting. Subsequently, the heat from the disks enters the block of electrochemical cells, increasing the duration of the current source. The high thermal conductivity of the disk material ensures that the temperature field is aligned with the diameter of the block of elements, which is especially important for the stable operation of the block of elements assembled from miniature parts. The high thermal conductivity of the disk material ensures that the temperature field is aligned with the diameter of the block of elements, which is especially important for the stable operation of the block, assembled from miniature parts. As the material of the disks, metals and their alloys resistant to lithium and not subject to corrosion when exposed to high temperatures can be used.

The ratio of the thickness of the heat storage disk to the thickness of the anode tablet determines the degree of minimization of the current source. With a ratio of less than 0.25, it is possible to melt the anode tablet and spread lithium along the block of electrochemical elements, at values greater than 0.35, to equalize the heat balance, it is necessary to increase the thickness of the anode tablet. This, in turn, will lead to the need to increase the thickness of the pyrotechnic tablet, and, as a consequence, to an increase in the overall dimensions of the current source.

A miniature thermal lithium current source (Figure 1) consists of a block of electrochemical elements 3 placed in a housing 1 and sealed with a cover with current leads 2, consisting of anode 4, electrolyte 5, cathode 6 and pyrotechnic 7 tablets and heat-accumulating conductive disks 8, laid between the anode and pyrotechnic tablets, the side surface of the block is tightly fitted by an ultra-thin pyrotechnic tape strip 9, which receives a fire pulse from the ignition device 10 and is thinly coated on the outside Leuna thermal insulation 11. At the ends of the block insulating gasket 12 installed.

When the current source is activated, the force of the flame from the ignition device is transmitted to an ultrathin pyrotechnic ribbon strip, which, when ignited, ignites pyrotechnic tablets inside the unit. Thus, heat from both pyrotechnic tablets and heat from the side pyrotechnic strip affects the block of electrochemical elements. The current source is operating.

The output electrical characteristics, activation time, and duration of operation are determined by thermal calculation, including the calculation of the heat balance of the electrochemical cell - pyrotechnic tablet system and the calculation of the unsteady temperature field taking into account the heat generated by the pyrotechnic tape strip surrounding the side surface of the block of electrochemical cells.

The proposed technical solution made it possible to obtain a current source with an external diameter not exceeding 8 mm. The height of the housing is not limited and depends mainly on the type of ignition device and the magnitude of the required voltage.

Claims (1)

A miniature thermal lithium current source containing a block of electrochemical elements placed in a housing and sealed by a lid, assembled from sequentially arranged anode, electrolyte, cathode and pyrotechnic tablets, the side surface of the block is covered with thermal insulation with a pyrotechnic element receiving a fire pulse from the ignition device, in the end parts are installed heat-insulating gaskets, characterized in that the pyrotechnic element is made in the form of an ultra-thin pyrotechnic strip, pl with respect to the lateral surface of the block of electrochemical elements, between the anode and pyrotechnic tablets, heat-accumulating conductive disks with a diameter equal to the diameter of the block of electrochemical elements and a thickness of 0.25-0.35 of the thickness of the anode tablet are installed.