RU2369944C2 - Thermal battery - Google Patents

Abstract

FIELD: electric engineering.

SUBSTANCE: invention is related to reserve chemical sources of current on solid body. According to invention thermal battery (TB) comprises unit of electrochemical elements (ECE), every of which consists of design number of solid layers of anode, cathode, electrolyte, heating elements, limited from external side by common body with heat and electric insulation. Unit of electrochemical elements (ECEU) is installed along vertical axis of body, is pressed in axial direction with specified force of design number of elastic elements with the possibility of this force value control by means of threaded element, additionally at ECEU ends there are passive ECE installed by one, body of TB is arranged as cylindrical of stainless steel with thickness of walls from 0.5 to 1 mm, anode of each ECE is made of single alloy LiB, cathode - out of mixture NiCl₂ and electroconductive additive, electrolyte from mixture of thickener and eutectic, comprising salts of alkaline metals, from internal and end sides of cylindrical body there are layers of heat and electric insulation, between layers of active masses there are solid layers of heating elements, in cylindrical body there are through vertical slots in the form of windows, total area of which does not exceed 80% of its total side surface.

EFFECT: higher resource of operation, energy intensity, reliability of battery operation, service life, mechanical strength of assembly, integrity.

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Description

The present invention relates to electrical engineering, to the field of backup chemical current sources on a solid, and can be used for the manufacture of a thermal battery with ionic conductivity.

A device is known for a heat battery containing a block of electrochemical cells, each of which is equipped with solid layers of anode, cathode, electrolyte, bounded from the outside by a common housing (RF patent No. 1833080, IPC Н01М 6/20, publ. 05.10.1995, BI No. 28/95).

The disadvantages of this device are not high enough energy consumption and the fact that there are no recommendations for meeting the requirements for mass-dimensional restrictions and the density of the assembly is not regulated during operation.

It is known as the closest in technical essence to the claimed device of a thermal battery (TB) (RF patent No. 2091918, IPC Н01М 6/36, publ. 09/27/1997, BI No. 27/97), containing a block of electrochemical elements, each of which is equipped with solid layers of the anode, cathode, electrolyte, heating elements, limited from the outside by a common housing with thermal insulation.

The disadvantages of the prototype include relatively low energy intensity, achieved density of the assembly and the level of electrochemical characteristics of the heat battery.

The task of the authors of the invention is to develop a thermal battery that meets the requirements for mass-dimensional restrictions, increasing the service life, energy consumption, battery reliability, increasing the shelf life, increasing the mechanical strength of the assembly, safety, increasing the density of the assembly, improving the electrochemical characteristics.

A new technical result obtained by using the present invention is to provide requirements for mass-dimensional restrictions, increase the service life by stabilizing the thermal regime, energy consumption, battery reliability, shelf life, increasing the mechanical strength of the assembly, safety, increasing the density of the assembly and improving electrochemical characteristics.

These tasks and a new technical result are achieved in that, in contrast to the known design of a heat battery containing a block of electrochemical cells, each of which is equipped with solid layers of anode, cathode, electrolyte, limited from the outside by a common housing with thermal insulation, in the proposed design, the block of electrochemical cells placed along the vertical axis of the housing, preloaded with a predetermined axial force by an elastic element with the ability to control the magnitude of this effort, the housing is a thermal ba the tare is cylindrical made of stainless steel with a wall thickness of at least 0.5-1.0 mm, the anode of each electrochemical cell is made of a lithium-boron alloy (LiB), the cathode is made of a mixture of NiCl ₂ and an electrically conductive additive, the electrolyte is made of a mixture of thickener and eutectics consisting of alkali metal salts, layers of heat and electrical insulation are made on the inner and end sides of the cylindrical body, solid layers of heat-heating elements are introduced between the layers of the active masses, vertical through slots are made in the cylindrical body windows, the total area of which does not exceed 80% of its total lateral surface.

The proposed thermal battery is illustrated as follows.

The proposed thermal battery is a cylindrical device shown in figure 1, consisting of a housing 1, a set of electrochemical elements (ECE) 2 and heating elements 3, an elastic element 4, metal gaskets 5, layers of heat and electrical insulation 8, 9, a threaded element 6 and two current leads 7, one of which is connected to the anode, the other to the cathode. Inside the housing there is an ECE unit located along the vertical axis of the housing and axially pushed with a predetermined force of the estimated number of elastic elements with the possibility of controlling the magnitude of this force by means of a threaded element. In the casing of the ECE block, slots 10 are made.

This embodiment limits the assembly on the outer surface, which significantly increases the operating time of the TB. In contrast to the traditional fixing of the ECE kit along the axis with an additional axial element, which required additional heat to heat it up, the proposed heating system achieved significant savings in heating energy.

The main working unit of the cell block is an electrochemical cell, which is a three-layer solid tablet (figure 2), where the anode 11 is made of a lithium-boron alloy (LiB), which has high energy characteristics. The cathode 12, which is a mixture of NiCl ₂ and an electrically conductive additive, has sufficient thermal stability in the working state in the temperature range 500-700 ° C when using chloride salts as an ion-conducting medium, as well as low solubility in the electrolyte. The electrolyte 13, which is a mixture of thickener and eutectic, consisting of alkali metal salts, acquires ionic conductivity at operating temperatures of TB, i.e. during melting. With increasing temperature, the electrical conductivity of ionic melts increases, which improves the electrochemical characteristics of TB compared with the prototype.

The required operating voltage of the TB is ensured by the serial connection (set in the “column”) of the ECE in the form of the calculated active masses minimized by the thickness of the layers. Thinning of the solid layers of the active masses effectively reduces the cost of thermal energy needed to heat the TB, and economically in terms of overall dimensions. To ensure the required operating time, in addition to the ends of the block of electrochemical elements, one passive ECE (not electrically connected to other ECE) is installed to equalize the temperature of the operating ECE along the axis of the cell block and for uniform distribution of the thermal field inside the TB. The ECE column is isolated from the inner cup body by layers of heat and electrical insulation 8, 9 (Fig. 1), and solid layers of heating elements are introduced between the layers of active masses.

These heating elements 3 (Fig. 1), pressed into a metal shell and installed between the ECE, serve to heat the ECE set to operating temperature and provide electrical connection between them. The package of ECE and heaters is pressed and fixed in the housing using an elastic element 4 and a threaded element 6 (figure 1), which allows to simplify the assembly of TB and make the fixation of ECE in the housing more rigid and dense than in the prototype, which in turn improves electrical ECE characteristics.

The TB incorporates an activation device with an electric igniter (EV), which brings it into working condition.

The principle of TB is as follows. When a current pulse is supplied to the EV bridge from an external current source, the EV is triggered and gives a force of flame to the means transmitting the heat pulse, during the combustion of which the heating elements located between the ECE are ignited. When the operating temperature is reached, the electrolyte becomes ion-conducting. When heated, the ion-conducting medium acquires the purely ionic conductivity of the electric current, and a potential difference arises on the ECE. The applied electrochemical system (ECS) in TB Li (B) / (LiCl-KCl) / NiCl ₂ , which is synthesized previously, works according to the following electrochemical reactions:

- anode: 2Li ⁰ -2e → 2Li ⁺

- cathode: Ni ²⁺ + 2e → Ni ⁰

Total reaction:

2Li + NiCl ₂ → 2LiCl + Ni

After the potential difference rises to the required value, the TB is ready for operation.

High temperatures of ionic melts, the use of energy-intensive electrochemical pairs (LiB-NiCl ₂ ) with a minimum content of impurities provides the TB with high specific indicators of the proposed TB - operating voltages (2.1-2.6 V per cell) and significant discharge current densities (up to 0 , 5 A / cm ² in pulsed mode), which significantly exceeds the achievements of the prototype.

To stabilize the thermal regime of TB by increasing the thermal and electrical insulation in the cylindrical body, through vertical slots are made in the form of windows 10 (Fig. 1), the total area of which does not exceed 80% of its total side surface. It was experimentally shown that their presence increases the energy intensity of the TB and the level of electrochemical and time parameters of the proposed TB due to the reduction of heat loss.

Thus, when using the proposed thermal battery, the requirements for mass-dimensional restrictions are provided, increasing the service life, energy consumption indicators, battery reliability, shelf life, mechanical strength of the assembly, safety, increased assembly density and improved electrochemical characteristics.

The possibility of industrial implementation of the proposed thermal battery is confirmed by the following example.

Example. The proposed thermal battery is implemented in laboratory conditions in the form of a prototype of a specific type and is a cylindrical device (figure 1), consisting of a housing 1 and heat and electrical insulation 8, 9. The housing is made of stainless steel 12X18H10T GOST 5632-72 with wall thickness 0.7 mm Inside the case is a block of electrochemical cells. Anode 1 (figure 2) is made of lithium boron alloy (LiB), which has high energy characteristics. Cathode 2 (FIG. 2) is a mixture of NiCl ₂ and an electrically conductive additive, chloride salts are used as the ion-conducting medium. Electrolyte 3 (Fig. 2) - a mixture of thickener and eutectic, consisting of a mixture of alkali metal salts, acquires ionic conductivity at operating temperatures of TB, i.e. during melting.

The required operating voltage of the TB is provided by serial connection (set in the "column") ECE 2 (figure 1) in the amount of 11 pieces. To ensure the required operating time, one additional passive ECE (not electrically connected to other ECEs) is installed at the ends of the block of elements, which helps to stabilize the thermal regime along the axis of the block of elements. The ECE column is insulated from the body by an insulating gasket 8 (Fig. 1) from mica, GSKV TU 3492-070-05758799-2002, along the side surface and gaskets 9 (Fig. 1) from Cardboard-N thermal insulation material, 4682601.013-89TU, at the ends.

To heat the ECE to the operating temperature and ensure electrical connection between them, pyrotechnic heaters 3 (Fig. 1), pressed between the ECE, are pressed into the metal shell. The package of ECE and heaters is pressed and fixed in the housing using an elastic element 4 (Fig. 1) and nut 6 (Fig. 1), which makes it easier to assemble the TB and make the fixation of the ECE in the housing more rigid, which in turn increases the resistance of TB to various mechanical influences and reduces electrical losses in the working condition of TB. The removal of the electric capacitance is performed using current outputs 7 (figure 1).

All data during the work of the proposed TB are summarized in table.

As experiments have shown, the use of the proposed TB meets the requirements for mass-dimensional restrictions, increasing the service life by stabilizing the thermal regime, energy consumption, battery reliability, shelf life, increasing the mechanical strength of the assembly, safety, increasing the density of the assembly and improving electrochemical characteristics.

Implementation examples The name of indicators The value of the proposed TB indicators The value of the TB prototype TB expiration date Note one 2 3 four 5 6 Electrochemical cell as part of the TB prototype (ECE indicators) Bit characteristics: Not high enough power consumption, runtime, assembly density, reliability Discharge current Up to 3.5 A Voltage 1.75-2.1 V Power density 9.3 kW / kg 17 years Working hours 350 s Volume working ECE 3.6 · 10 ^-6 m ³ Mass EChE 7.41 · 10 ^-3 kg The electrochemical element in the composition of the proposed TB (indicators for ECE) Bit characteristics: Improvement in characteristics: operating time, removable capacity, reliability, assembly density, stabilization of thermal conditions Discharge current Up to 7A Voltage 2.6 V Power density 30 kW / kg 17 years Working hours up to 600 s Volume working ECE 3.0 · 10 ^-6 m ³ Mass EChE 6.27 · 10 ^-3 kg

Claims (1)

A thermal battery containing a block of electrochemical cells, each of which consists of a calculated number of solid layers of the anode, cathode, electrolyte, heating elements bounded on the outside by a common body with heat and electrical insulation, characterized in that the block of electrochemical cells is placed along the vertical axis of the body pushed in the axial direction with a given force of the estimated number of elastic elements with the possibility of regulating the magnitude of this effort by means of a threaded element, additional about at the ends of the block of electrochemical cells one passive electrochemical cell was installed, the case of the thermal battery is made of cylindrical stainless steel with a wall thickness of 0.5 to 1 mm, the anode of each electrochemical cell is made of one LiB alloy, the cathode is a mixture of NiCl ₂ and electrically conductive additives, an electrolyte from a mixture of a thickener and a eutectic consisting of alkali metal salts, layers of heat and electrical insulation are made from the inner and end sides of the cylindrical body, introduced between the layers of active masses solid layers of heating elements, in the cylindrical body there are made through vertical slots in the form of windows, the total area of which does not exceed 80% of its total lateral surface.

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