CN109167080B - High-voltage lithium thermal battery - Google Patents

Abstract

_The invention relates to a high _- voltage lithium thermal battery, which uses _{nickel chloride} as a positive electrode material, and uses a solid electrolyte as an electrolyte. Grind the solid electrolyte into electrolyte powder, add the nickel chloride positive electrode material to no more than 20% of the solid electrolyte and mix well, grind to make a positive electrode powder, and press it into layers after spreading to make a positive electrode/electrolyte sheet, according to the positive electrode current collector. /positive electrode/electrolyte sheet/negative electrode sheet/negative electrode current collector are sequentially compressed and then loaded into the battery case. The battery has simple steps, cheap and readily available raw materials, can eliminate the leaching problem of nickel chloride and traditional electrolytes, effectively eliminate potential safety hazards, and can give full play to the advantages of nickel chloride material with high theoretical capacity and positive electrode potential.

Description

A high-voltage lithium thermal battery

technical field

The present invention relates to a high-voltage lithium thermal battery. It belongs to the technical field of lithium thermal batteries.

Background technique

Thermal batteries, also known as molten salt batteries, have the advantages of high specific energy and specific power, strong environmental adaptability, long storage time, fast activation speed, and no maintenance. They have developed rapidly since their invention at the end of World War II. , become the preferred power source for weapons and equipment. However, modern weapons put forward higher requirements on the voltage and power of thermal batteries. Compared with the rapid development of weapons and equipment, the development of thermal battery technology lags behind significantly.

Current research shows that the battery performance mainly depends on the improvement of the performance of the cathode active material, and the exploration of cathode materials with excellent performance is the key to obtain high-performance thermal batteries. Cobalt disulfide is a commonly used cathode material for thermal batteries in recent years. It has the characteristics of low internal resistance, strong load capacity, small polarization at large currents, and high output voltage accuracy under variable loads. However, the thermal battery prepared by CoS is limited by the low voltage around 2.0V, and there is limited space for further improving the specific energy _on the existing basis. Therefore, people have been constantly seeking new cathode materials for thermal batteries. Nickel chloride material has the characteristics of high theoretical capacity, high discharge current density, positive electrode potential, stable discharge platform, etc. Its decomposition temperature is above 900 ℃, and its thermal stability is good. The NiCl ₂ material is matched with the lithium alloy negative electrode, and the voltage reaches 2.5V, which shows excellent performance and is considered to be one of the ideal materials to replace the sulfur-based positive electrode material.

Unfortunately, the electrolytes used in current thermal batteries are mostly molten salt electrolytes such as LiCl-LiBr-LiF. When these electrolytes are discharged at high temperature, after the electrolyte is melted, the nickel chloride electrode material and the electrolyte "immerse" and overflow out of the electrode. The chip will cause a short circuit in the battery, which will cause serious safety problems and affect the practical application of nickel chloride.

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, the present invention adopts the solid electrolyte and the nickel chloride positive electrode to match to prepare the high-voltage thermal battery. The method has simple steps, cheap and readily available raw materials, can eliminate the leaching problem of nickel chloride and traditional electrolytes, effectively eliminate the potential safety hazard, and give full play to the advantages of nickel chloride material with high theoretical capacity and positive electrode potential.

The technical scheme of the present invention is as follows:

A high-voltage lithium thermal battery, the preparation method of which comprises the following steps:

(1) Grind the solid electrolyte into electrolyte powder;

(2) The nickel chloride positive electrode material is added to a certain proportion of solid electrolyte, mixed, and ground into positive electrode powder;

(3) layering and pressing the powders of step (2) and step (1) together to form a positive electrode/electrolyte sheet;

(4) Press the positive electrode current collector/positive electrode/electrolyte sheet/negative electrode sheet/negative electrode current collector in the order and put it into the battery case.

Preferably, in the present invention, the solid electrolyte in step (1) is a Li ₇ La ₃ Zr ₂ O ₁₂ solid electrolyte or a solid electrolyte modified by doping.

Preferably, in the present invention, the certain proportion of solid electrolyte in step (2) accounts for no more than 20% of the positive electrode powder.

Preferably, in the present invention, the negative electrode sheet in step (4) can be a lithium-silicon alloy or a lithium-boron alloy, more preferably a lithium-boron alloy.

The voltage of the thermal battery cell prepared according to the above technical solution is about 2.5V, and the positive electrode material and the electrolyte will not be leached during discharge.

The beneficial effects of the present invention are as follows:

The invention adopts the solid electrolyte and nickel chloride to match to prepare the thermal battery, the voltage of the single battery is relatively high, up to about 2.5V, and the method has simple steps, does not need to modify the existing production line, the raw materials are cheap and easy to obtain, and the nickel chloride can be eliminated. It can effectively eliminate the safety hazard and give full play to the advantages of high theoretical capacity and positive electrode potential of nickel chloride material.

Description of drawings

Fig.1 Spillover of solid electrolyte (LLZO) and all-lithium electrolyte (LiCl-LiBr-LiF), (a) LLZO electrolyte, (b) all-lithium electrolyte

The battery prepared in Example 1 was disassembled after the discharge test at 550°C and current density of 80 mA·cm ^-2 , and compared with the molten salt electrolyte thermal battery in Comparative Example 1. The results are shown in Figure 1 . From Figure 1, we can see that after the lithium thermal battery using Li ₇ La ₃ Zr ₂ O ₁₂ solid electrolyte (LLZO) as the electrolyte is discharged, the edge of the mica separator is clean, and the LLZO still maintains the original solid shape and does not melt. With flow, there is no overflow phenomenon of the positive electrode sheet. On the other hand, the Li-thermal battery using the traditional all-lithium electrolyte (LiCl-LiBr-LiF) can observe obvious melting phenomenon on the nickel sheet and mica sheet after high-temperature discharge, indicating that the electrode material overflows out of the electrode sheet after high-temperature discharge.

specific embodiment

The present invention will be further described in detail below with reference to specific embodiments. These examples are only intended to illustrate the present invention, but do not limit the scope of the present invention. In addition, after reading the specific embodiments described in the present invention, those skilled in the art can make modifications and changes to the present invention, but these equivalent forms also belong to the scope defined by the patent specification of the present application.

Example 1

(1) Grind the Li ₇ La ₃ Zr ₂ O ₁₂ solid electrolyte into electrolyte powder and pass through a 200-mesh sieve;

(2) Add the nickel chloride positive electrode material to 10% solid electrolyte and mix, and grind to make positive electrode powder;

(3) Weigh 0.9 g of positive electrode powder and 0.1 g of electrolyte powder, and press them into layers to form a positive electrode/electrolyte sheet;

(4) Press the positive electrode current collector/positive electrode/electrolyte sheet/negative electrode sheet/negative electrode current collector in the order and put it into the battery case.

The prepared battery was disassembled after discharge test at 550°C and a current density of 80 mA·cm ^-2 , and the positive electrode sheet did not overflow.

Example 2

(1) The Li _6.7 Fe _0.1 La ₃ Zr ₂ O ₁₂ solid electrolyte modified with Fe doping was ground into electrolyte powder and passed through a 200-mesh sieve;

(2) The nickel chloride positive electrode material was added to 8% solid electrolyte and mixed, and ground to make positive electrode powder;

(3) Weigh 0.9 g of positive electrode powder and 0.1 g of electrolyte powder, and press them into layers to make a positive electrode/electrolyte sheet;

(4) Press the positive electrode current collector/positive electrode/electrolyte sheet/negative electrode sheet/negative electrode current collector in the order and put it into the battery case.

The prepared battery was disassembled after discharge test at 550°C and a current density of 80 mA·cm ^-2 , and the positive electrode sheet did not overflow.

Comparative Example 1

(1) Add 20% magnesium oxide to the full lithium electrolyte and grind it into an electrolyte powder and pass through a 200-mesh sieve;

(2) Add the nickel chloride positive electrode material to 8% electrolyte powder and mix, and grind to make positive electrode powder;

(3) Weigh 0.9 g of positive electrode powder and 0.1 g of electrolyte powder, and press them into layers to make a positive electrode/electrolyte sheet;

Press the positive electrode current collector/positive electrode/electrolyte sheet/negative electrode sheet/negative electrode current collector in the order and put them into the battery case.

The prepared battery was discharged at 550°C and the current density was 80 mA·cm ^-2 . The battery quickly failed, and the electrode sheet overflowed obviously after dismantling.

Claims (1)

1. The lithium thermal battery is characterized in that the positive electrode of the lithium thermal battery is nickel chloride, the negative electrode of the lithium thermal battery is lithium boron alloy, and the electrolyte is Li₇La₃Zr₂O₁₂A solid electrolyte or a doped modified solid electrolyte thereof.

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