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Composite negative electrode for thermal battery and preparation method thereof

A thermal battery and negative electrode technology, applied to battery electrodes, primary battery electrodes, circuits, etc., can solve the problems of unable to quickly establish a stable platform voltage, poor discharge rate characteristics, large interface resistance, etc., to achieve great application value and economy Significance, reducing polarization internal resistance, and improving the effect of power output capability

Active Publication Date: 2021-06-04
SHANGHAI INST OF SPACE POWER SOURCES
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

LiB alloy is composed of a sponge-like porous Li7B6 skeleton and metallic lithium embedded in the pores. Free lithium directly participates in the electrode reaction, and the lithium content directly determines the battery capacity. At the same time, its actual utilization rate can reach more than 90%, which is much higher than that of LiSi. The utilization rate of the alloy (~75%); but in addition to the above advantages, due to the existence of the dense framework of the LiB alloy, there is a large interface resistance between the negative electrode layer and the isolation layer, which leads to the fact that the thermal battery cannot be quickly established after receiving the activation signal. Stable plateau voltage, long activation time and poor discharge rate characteristics
[0004] At present, the method to improve the initial performance of activation is mainly to increase the content of free lithium in LiB alloy (Applied Chemical Industry, 2015.44(5):947), but this method is prone to lithium overflow, which leads to safety problems of thermal batteries

Method used

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  • Composite negative electrode for thermal battery and preparation method thereof
  • Composite negative electrode for thermal battery and preparation method thereof
  • Composite negative electrode for thermal battery and preparation method thereof

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preparation example Construction

[0027] Here, aiming at the problem of slow voltage build-up and “voltage pits” caused by insufficient ion activity at the initial stage of activation when LiB alloy is used as the negative electrode material for thermal batteries, the present invention provides a composite negative electrode for thermal batteries and a preparation method thereof. LiSi Compatible with LiB, and modify the thin electrolyte coating layer on the surface of the composite negative electrode, so that the composite negative electrode can quickly enter the activation state after receiving the activation signal, improve the activation speed of LiB system thermal battery, and reduce the polarization internal resistance. The composite negative pole of the present invention is especially suitable for power type fast activation heat battery.

[0028] In an embodiment of the composite negative electrode for thermal battery of the present invention, the weight of the LiSi alloy powder layer is 10%-25% of the sh...

Embodiment 1

[0044]A composite negative electrode for thermal batteries, the mass percent of its composition is: LiSi alloy powder weight is 20% of LiB alloy; Then, under the protection of argon atmosphere, place 0.15g of all-lithium molten salt electrolyte in the heating tank at the upper end of the quartz drainage tube, heat at 450°C for 10min, and the molten electrolyte diffuses on the composite negative electrode sheet (LiSi side) surface, it can be solidified and formed after standing at room temperature for a while. The LiB negative thermal battery that adopts routine assembly, activation time is 0.89s, and internal resistance is 0.72mΩ / cm Compared with the conventionally assembled LiB negative electrode battery, the activation time is shortened by 47.2%, and the internal resistance is reduced by 33.4% (the battery activation is shown in figure 2 , see the change of internal resistance image 3 ).

Embodiment 2

[0046] A composite negative electrode for thermal batteries, the mass percent of its composition is: LiSi alloy powder weight is 15% of LiB alloy; Then, under the protection of argon atmosphere, place 0.1g of all-lithium molten salt electrolyte in the heating tank at the upper end of the quartz drainage tube, heat at 450°C for 5min, and the molten electrolyte diffuses on the composite negative electrode sheet (LiSi side) surface, it can be solidified and formed after standing at room temperature for a while. The thermal battery assembled using the composite negative electrode sheet described in Example 1 has an activation time of 0.51s and an internal resistance of 0.5mΩ / cm2. Compared with the conventionally assembled LiB negative electrode battery, the activation time is shortened by 42.7%, and the internal resistance is reduced by 30.5%.

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Abstract

The invention provides a composite negative electrode for a thermal battery and a preparation method thereof. The composite negative electrode is mainly formed by physical pressing of a flake LiB alloy and a powdered LiSi alloy, and the LiSi alloy powder is 10% to 25% of the weight of the LiB alloy; LiSi The surface of the alloy powder is coated with molten salt electrolyte, and after forming a single battery, it is in direct contact with the isolation layer. During the activation process of the thermal battery, the electrolyte coating on the surface of the composite negative electrode quickly enters the activated state, and establishes ion migration channels with the negative electrode, which effectively improves the activation speed of the thermal battery. In the composite negative electrode of the present invention, the interface polarization internal resistance between the separator and the coated LiSi layer is significantly reduced, which is conducive to the rapid and stable pressure building of the thermal battery, and improves the LiB negative electrode caused by insufficient ion activity in the initial stage of work. The problem of "voltage pit" is especially suitable for the design of power type thermal battery.

Description

technical field [0001] The invention relates to a composite negative electrode for a thermal battery and a preparation method thereof. Background technique [0002] Thermal battery is a storage battery whose electrolyte is a non-conductive solid. When in use, an electric ignition head or a firing pin mechanism is used to ignite the heating agent inside, so that the electrolyte melts into a high-conductivity ion conductor and is activated as a reserve battery. The negative electrode material of the thermal battery is usually made of lithium-based metals with low electrode potential, but since the melting point of elemental lithium is lower than the operating temperature of the thermal battery, direct use may cause short circuit or corrosion inside the battery, so the actual production usually uses safer Lithium alloys such as LiSi, LiX (X=Fe, Al). [0003] Recently, LiB alloy has received extensive attention due to its advantages of negative potential, high capacity, and eas...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/06H01M4/08H01M4/36H01M4/58H01M4/62H01M6/36
CPCH01M4/06H01M4/08H01M4/366H01M4/58H01M4/628H01M6/36
Inventor 韩婷婷强杉杉郑侠刘凯特张维义胡华荣江黎莉
Owner SHANGHAI INST OF SPACE POWER SOURCES
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