CN114792847B - A low-temperature liquid metal battery and a method for preparing the same - Google Patents

Abstract

The present invention discloses a low-temperature liquid metal battery and a preparation method thereof, wherein the battery comprises a housing and a positive electrode, a negative electrode and an electrolyte sealed in the housing, wherein the negative electrode comprises metallic lithium; the electrolyte comprises two or more metal halide salts, the metal halide salts comprise lithium halides, and also comprise rubidium halides and/or cesium halides, and the melting point of the electrolyte does not exceed 300° C. By introducing rubidium ions and cesium ions into the electrolyte of the liquid metal battery, the melting point of the electrolyte is greatly reduced without sacrificing the stability of the electrolyte.

Description

A low-temperature liquid metal battery and a method for preparing the same

Technical Field

The present invention belongs to the technical field of energy storage batteries, and more specifically, relates to a low-temperature liquid metal battery and a preparation method thereof.

Background technique

Liquid metal batteries are composed of three layers of immiscible liquids. In theory, they have an extremely long service life and are very suitable for large-scale static energy storage at the grid level. However, in order to meet the melting points of electrodes and electrolytes at the same time, liquid metal batteries need to operate at high temperatures. For example, the operating temperatures of currently competitive liquid metal battery systems such as Li||Sb-Pb, Li||Sb-Sn, Li||Bi, Li||Sb, Ca-Mg||Bi, etc. are 480℃～550℃. The high operating temperature poses a huge challenge to battery sealing and corrosion protection, and increases a lot of additional heat preservation power consumption. Therefore, it is of great theoretical and practical significance to develop a liquid metal battery that inherits the core advantages of liquid metal batteries (self-healing of electrode deformation, no side reactions between electrolyte and active electrode) and has a lower operating temperature.

Summary of the invention

In view of the above defects or improvement needs of the prior art, the present invention provides a low-temperature liquid metal battery and a preparation method thereof, the purpose of which is to reduce the operating temperature of the liquid metal battery.

To achieve the above object, according to one aspect of the present invention, there is provided a low-temperature liquid metal battery, comprising a housing and a positive electrode, a negative electrode and an electrolyte sealed in the housing.

The negative electrode includes metallic lithium;

The electrolyte includes two or more metal halide salts, wherein the metal halide salts include lithium halides and also include rubidium halides and/or cesium halides. The melting point of the electrolyte does not exceed 300°C.

In one embodiment, the electrolyte is any combination of the following:

LiBr _20-60 -RbBr _80-40 ;

LiBr _20-60 -CsCl _80-40 ;

LiBr _40-80 -CsBr _60-20 ;

LiI _45-85 -CsI _55-15 ;

LiCl _20-80 -KCl _0-30 -CsCl _0-40 ;

LiCl _40-80 -KCl _10-30 -RbCl _0-20 -CsCl _0-40 ;

LiBr _40-80 -KBr _10-30 -CsBr _0-40 ;

LiI _40-80 -KI _0-30 -CsI _0-40 ;

LiBr _5-20 -LiI _40-80 -KI _10-30 -CsI _10-40 ;

LiCl _1-10 -LiBr _0-20 -LiI _30-70 -KI _0-30 -CsI _0-40 ;

The sum of the molar percentages of the components in the electrolyte is equal to 100%.

In one embodiment, the positive electrode is an alloy of two metals selected from antimony, bismuth, tin and lead.

In one embodiment, the positive electrode is any one of the following:

Bi _10-90 -Sn _90-10 alloy;

Bi _10-90 -Pb _90-10 alloy;

Sn _10-90 -Pb _90-10 alloy;

Sb _5-50 -Pb _95-50 alloy;

The sum of the molar percentages of the components in each positive electrode alloy is equal to 100%.

In one embodiment, a negative electrode current collector is also included, and the negative electrode current collector is foamed iron nickel or foamed carbon.

According to another aspect of the present invention, there is provided a method for preparing a low-temperature liquid metal battery, comprising:

Under the protection of inert gas, the positive electrode material is placed in a crucible, heated and melted, and then naturally cooled to form a positive electrode, and the crucible is placed in a matching stainless steel shell;

Under the protection of an inert gas, the electrolyte material is heated and melted and poured into the crucible to form an electrolyte; the electrolyte comprises two or more metal halide salts, the metal halide salts comprise lithium halides, and also comprise rubidium halides and/or cesium halides, and the melting point of the electrolyte does not exceed 300° C.;

Under the protection of inert gas, the liquid metal lithium is absorbed by the negative electrode current collector, and the negative electrode current collector adsorbing the metal lithium and the top cover are assembled on the shell, followed by natural cooling;

The shell and the top cover are welded to obtain an assembled low-temperature liquid metal battery.

In one embodiment, the positive electrode is an alloy formed by two metals selected from antimony, bismuth, tin and lead;

The positive electrode material is placed in a crucible and heated to melt, including:

Each metal that makes up the alloy is placed in a crucible and heated to melt each metal into an alloy.

In one embodiment, the alloy is any one of the following:

Bi _10-90 -Sn _90-10 alloy;

Bi _10-90 -Pb _90-10 alloy;

Sn _10-90 -Pb _90-10 alloy;

Sb _5-50 -Pb _95-50 alloy;

The sum of the molar percentages of the components in each alloy is equal to 100%.

In one embodiment, the electrolyte is any combination of the following:

LiBr _20-60 -RbBr _80-40 ;

LiBr _20-60 -CsCl _80-40 ;

LiBr _40-80 -CsBr _60-20 ;

LiI _45-85 -CsI _55-15 ;

LiCl _20-80 -KCl _0-30 -CsCl _0-40 ;

LiCl _40-80 -KCl _10-30 -RbCl _0-20 -CsCl _0-40 ;

LiBr _40-80 -KBr _10-30 -CsBr _0-40 ;

LiI _40-80 -KI _0-30 -CsI _0-40 ;

LiBr _5-20 -LiI _40-80 -KI _10-30 -CsI _10-40 ;

LiCl _1-10 -LiBr _0-20 -LiI _30-70 -KI _0-30 -CsI _0-40 ;

The sum of the molar percentages of the components in each combination is equal to 100%.

In one embodiment, the negative electrode current collector is foamed iron nickel or foamed carbon.

In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

The present invention proposes to further add rubidium ions/cesium ions to the electrolyte to form a multi-component mixed cation electrolyte. Researchers generally believe that the addition of rubidium ions and cesium ions will cause instability in battery operation, because usually metallic lithium can replace the rubidium ions and cesium ions in the electrolyte, forming rubidium vapor and cesium vapor to escape. In other words, researchers generally believe that when metallic lithium is used for the negative electrode, the electrolyte whose cations are only lithium ions is stable, and due to the existence of the replacement reaction, the electrolyte containing rubidium ions and cesium ions is unstable. This research and development team combined theoretical analysis and experimental proof and believed that the above-mentioned replacement reaction can only occur under constant pressure conditions, while liquid metal batteries work under strictly sealed conditions, which belong to constant volume conditions. The degree of occurrence of the above-mentioned replacement reaction is negligible. Therefore, the multi-component cation electrolyte containing potassium ions, rubidium ions and cesium ions is stable. Therefore, the present invention breaks the conventional thinking and adds rubidium ions/cesium ions to the electrolyte to maintain the stability of the electrolyte. Experiments have shown that adding rubidium ions/cesium ions to the electrolyte to form a multi-mixed cation electrolyte can reduce the melting point of the electrolyte to below 300°C, thereby greatly reducing the operating temperature of the battery.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of a liquid metal battery according to an embodiment;

FIG2 is a diagram showing the decomposition potential of rubidium ions, cesium ions and lithium ions according to an embodiment;

FIG3 is a graph showing the melting point of a LiCl-LiBr-LiI-KI-CsI electrolyte before battery operation according to an embodiment;

FIG4 is a graph showing the melting point of a LiCl-LiBr-LiI-KI-CsI electrolyte after battery operation according to an embodiment;

FIG5 is a charge and discharge curve diagram of the battery in Example 4 at 290 degrees;

FIG6 is a cycle performance diagram of the battery in Example 4 at 290 degrees;

FIG. 7 is a discharge curve diagram of the battery in Example 8 at 220 degrees.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

As shown in FIG1 , it is a schematic diagram of the structure of a liquid metal battery in an embodiment, which includes a shell 3 and a negative electrode 4, an electrolyte 5 and a positive electrode 6 enclosed in the shell 4. Among them, the negative electrode 4 includes metallic lithium, and the electrolyte 5 includes two or more metal halide salts, the metal halide salts include lithium halides, and also include rubidium halides and/or cesium halides, and the melting point of the electrolyte does not exceed 300° C. Among them, the metallic lithium in the negative electrode is adsorbed on the negative electrode current collector and led out through the negative electrode lead 1, and the negative electrode lead 1 is electrically isolated from the shell 3 by the insulator 2.

As shown in Figure 2, the decomposition potential diagram of rubidium ions, cesium ions and lithium ions, rubidium ions and cesium ions will not participate in the electrochemical reaction and will not affect the charge and discharge process of the battery due to their lower reduction potential. In one embodiment, the charge and discharge rate of the battery is 0.05-0.5C.

In normal operation, due to the replacement of rubidium ions and cesium ions in the metal lithium electrolyte, taking iodide as an example, it is generally believed that the following replacement reaction will occur:

Li+RbI＝LiI+Rb

Li+CsI＝LiI+Cs

Therefore, in traditional thinking, researchers generally believe that when the negative electrode uses metallic lithium, rubidium ions/cesium ions cannot be added to the electrolyte.

After analysis, the research and development team found that the essential reason why this type of reaction can occur is that the vapor pressure of metallic rubidium and cesium is much higher than that of metallic lithium. The replaced trace rubidium/cesium continues to evaporate in the form of vapor, forcing the chemical reaction equilibrium to move to the right. Therefore, the above replacement reaction can only occur under constant pressure conditions. Liquid metal batteries work under strictly sealed conditions (constant volume conditions). The replaced rubidium/cesium vapor cannot evaporate, and the chemical reaction equilibrium cannot shift to the right. Therefore, the polyvalent cationic electrolyte containing rubidium ions and cesium ions is stable. As shown in Figure 3, the melting point of the LiCl-LiBr-LiI-KI-CsI electrolyte before the battery is operated is determined, and as shown in Figure 4, the melting point of the battery after several months of operation is determined. It is found that the melting point of the battery before and after operation is consistent, which means that the electrolyte properties are stable, and it can also be seen from Figures 3 and 4 that the battery operating temperature drops to about 220°C.

In a specific embodiment, the chemical formula of the molten salt electrolyte is:

LiBr _20-60 -RbBr _80-40 (the lowest melting point of this system is 271°C);

LiBr _20-60 -CsCl _80-40 (the lowest melting point of this system is 262°C);

LiBr _40-80 -CsBr _60-20 (the lowest melting point of this system is 259°C);

LiI _45-85 -CsI _55-15 (the lowest melting point of this system is 217°C);

LiCl _20-80 -KCl _0-30 -CsCl _0-40 (the lowest melting point of this electrolyte is 265°C);

LiCl _40-80 -KCl _10-30 -RbCl _0-20 -CsCl _0-40 (the lowest melting point of this system is 258°C);

LiBr _40-80 -KBr _10-30 -CsBr _0-40 (the lowest melting point of this system is 236°C);

LiI _40-80 -KI _0-30 -CsI _0-40 (the lowest melting point of this system is 205°C);

LiBr _5-20 -LiI _40-80 -KI _10-30 -CsI _10-40 (the lowest melting point of this system is 189°C);

LiCl _1-10 -LiBr _0-20 -LiI _30-70 -KI _0-30 -CsI _0-40 (the lowest melting point of this system is 184℃).

In one embodiment, the positive electrode is an alloy of any two metals selected from bismuth, tin, and lead. Specifically, any one of the following can be selected:

Bi _10-90 -Sn _90-10 alloy (the lowest melting point of this alloy is 141°C);

Bi _10-90 -Pb _90-10 alloy (the lowest melting point of this alloy is 125°C);

Sn _10-90 -Pb _90-10 alloy (the lowest melting point of this alloy is 182°C);

Sb _5-50 -Pb _95-50 alloy (the lowest melting point of this alloy is 252℃).

Accordingly, the present application also relates to a method for preparing a low-temperature liquid metal battery, the method comprising:

Under the protection of inert gas, the positive electrode material is placed in a crucible, heated and melted, and then naturally cooled to form a positive electrode, and the crucible is placed in a matching stainless steel shell;

Under the protection of an inert gas, the electrolyte material is heated and melted and poured into the crucible to form an electrolyte; the electrolyte comprises two or more metal halide salts, the metal halide salts comprise lithium halides, and also comprise rubidium halides and/or cesium halides, and the melting point of the electrolyte does not exceed 300° C.;

Under the protection of inert gas, the liquid metal lithium is absorbed by the negative electrode current collector, and the negative electrode current collector adsorbing the metal lithium and the top cover are assembled on the shell, followed by natural cooling;

The shell and the top cover are welded to obtain an assembled low-temperature liquid metal battery.

The selection of materials for the positive electrode, negative electrode and electrolyte can refer to the above introduction and will not be repeated here.

The present invention is further described in detail below in conjunction with specific embodiments.

Example 1

A Li||Bi-Sn liquid metal battery operating at 280°C is carried out in the following steps:

(1) Under the protection of inert gas, weigh 13 g of bismuth particles and 11 g of tin particles and place them in a graphite crucible (inner diameter 56 mm);

(2) Under the protection of inert gas, the graphite crucible is heated to 300° C. on a heating plate and kept at this temperature for 1 hour to melt the metal bismuth and the metal tin to form an alloy; then the crucible is naturally cooled to room temperature, and then the graphite crucible is placed in a stainless steel shell of a matching size;

(3) Under the protection of inert gas, 1.3 g of liquid metal lithium was absorbed by foamed carbon as the negative electrode;

(4) Under the protection of inert gas, heat and melt 60 g of dried LiBr-RbBr (molar ratio: 42-58) mixed salt and pour it into the aforementioned graphite crucible;

(5) Under the protection of inert gas, assemble the negative electrode current collector (carbon foam) adsorbed with metal and the top cover onto the shell to which the molten salt (not solidified) has been added, and then cool naturally to room temperature;

(6) Welding the shell and the top cover by laser welding or argon arc welding to obtain an assembled battery;

(7) The battery is placed in a test furnace, heated to the operating temperature and maintained at a constant temperature, and connected to a battery test system for battery testing.

Example 2

A Li||Bi-Sn liquid metal battery operating at 270°C is carried out in the following steps:

(1) Under the protection of inert gas, weigh 13 g of bismuth particles and 11 g of tin particles and place them in a graphite crucible (inner diameter 56 mm);

(2) Under the protection of inert gas, the graphite crucible is heated to 300° C. on a heating plate and kept at this temperature for 1 hour to melt the metal bismuth and the metal tin to form an alloy; then the crucible is naturally cooled to room temperature, and then the graphite crucible is placed in a stainless steel shell of a matching size;

(3) Under the protection of inert gas, 1.3 g of liquid metal lithium was absorbed by foamed carbon as the negative electrode;

(4) Under the protection of inert gas, 60 g of dried LiBr-CsCl (molar ratio: 42-58) mixed salt was heated and melted, and poured into the aforementioned graphite crucible;

(5) Under the protection of inert gas, assemble the negative electrode current collector (carbon foam) adsorbed with metal and the top cover onto the shell to which the molten salt (not solidified) has been added, and then cool naturally to room temperature;

(6) Welding the shell and the top cover by laser welding or argon arc welding to obtain an assembled battery; (7) Placing the battery in a test furnace, heating it to the operating temperature and maintaining a constant temperature, and connecting it to a battery testing system for battery testing.

Example 3

A Li||Bi-Sn liquid metal battery operating at 265°C is carried out in the following steps:

(1) Under the protection of inert gas, weigh 13 g of bismuth particles and 11 g of tin particles and place them in a graphite crucible (inner diameter 56 mm);

(2) Under the protection of inert gas, the graphite crucible is heated to 300° C. on a heating plate and kept at this temperature for 1 hour to melt the metal bismuth and the metal tin to form an alloy; then the crucible is naturally cooled to room temperature, and then the graphite crucible is placed in a stainless steel shell of a matching size;

(3) Under the protection of inert gas, 1.3 g of liquid metal lithium was absorbed by foamed carbon as the negative electrode;

(4) Under the protection of inert gas, 60 g of dried LiBr-CsBr (molar ratio: 59-41) mixed salt was heated and melted and poured into the aforementioned graphite crucible;

(5) Under the protection of inert gas, assemble the negative electrode current collector (carbon foam) adsorbed with metal and the top cover onto the shell to which the molten salt (not solidified) has been added, and then cool naturally to room temperature;

(6) Welding the shell and the top cover by laser welding or argon arc welding to obtain an assembled battery; (7) Placing the battery in a test furnace, heating it to the operating temperature and maintaining a constant temperature, and connecting it to a battery testing system for battery testing.

Example 4

A Li||Bi-Sn liquid metal battery operating at 290°C is carried out in the following steps:

(1) Under the protection of inert gas, weigh 13 g of bismuth particles and 11 g of tin particles and place them in a graphite crucible (inner diameter 56 mm);

(2) Under the protection of inert gas, the graphite crucible is heated to 300° C. on a heating plate and kept at this temperature for 1 hour to melt the metal bismuth and the metal tin to form an alloy; then the crucible is naturally cooled to room temperature, and then the graphite crucible is placed in a stainless steel shell of a matching size;

(3) Under the protection of inert gas, 1.3 g of liquid metal lithium was absorbed by foamed carbon as the negative electrode;

(4) Under the protection of inert gas, 60 g of dry LiCl-KCl-CsCl (molar ratio: 72.5-13.3-14.2) mixed salt was heated and melted, and poured into the aforementioned graphite crucible;

(5) Under the protection of inert gas, assemble the negative electrode current collector (carbon foam) adsorbed with metal and the top cover onto the shell to which the molten salt (not solidified) has been added, and then cool naturally to room temperature;

(6) The shell and the top cover are welded by laser welding or argon arc welding to obtain an assembled battery; (7) The battery is placed in a test furnace, heated to the operating temperature and maintained at a constant temperature, and connected to a battery testing system for battery testing. FIG5 shows the charge and discharge curve of the battery at 290 degrees, and FIG6 shows the cycle performance of the battery at 290 degrees, indicating that the charge and discharge process is stable and the cycle period is long.

Example 5

A Li||Bi-Sn liquid metal battery operating at 245°C is carried out in the following steps:

(1) Under the protection of inert gas, weigh 13 g of bismuth particles and 11 g of tin particles and place them in a graphite crucible (inner diameter 56 mm);

(2) Under the protection of inert gas, the graphite crucible is heated to 300° C. on a heating plate and kept at this temperature for 1 hour to melt the metal bismuth and the metal tin to form an alloy; then the crucible is naturally cooled to room temperature, and then the graphite crucible is placed in a stainless steel shell of a matching size;

(3) Under the protection of inert gas, 1.3 g of liquid metal lithium was absorbed by foamed carbon as the negative electrode;

(4) Under the protection of inert gas, 60 g of dried LiBr-KBr-CsBr (molar ratio: 56.1-18.1-25.3) mixed salt was heated and melted, and poured into the aforementioned graphite crucible;

(5) Under the protection of inert gas, assemble the negative electrode current collector (carbon foam) adsorbed with metal and the top cover onto the shell to which the molten salt (not solidified) has been added, and then cool naturally to room temperature;

(6) Welding the shell and the top cover by laser welding or argon arc welding to obtain an assembled battery; (7) Placing the battery in a test furnace, heating it to the operating temperature and maintaining a constant temperature, and connecting it to a battery testing system for battery testing.

Example 6

A Li||Bi-Sn liquid metal battery operating at 210°C is carried out in the following steps:

(1) Under the protection of inert gas, weigh 13 g of bismuth particles and 11 g of tin particles and place them in a graphite crucible (inner diameter 56 mm);

(2) Under the protection of inert gas, the graphite crucible is heated to 300° C. on a heating plate and kept at this temperature for 1 hour to melt the metal bismuth and the metal tin to form an alloy; then the crucible is naturally cooled to room temperature, and then the graphite crucible is placed in a stainless steel shell of a matching size;

(3) Under the protection of inert gas, 1.3 g of liquid metal lithium was absorbed by foamed carbon as the negative electrode;

(4) Under the protection of inert gas, 60 g of dried LiI-KI-CsI (molar ratio: 56.1-18.1-25.3) mixed salt was heated and melted, and poured into the aforementioned graphite crucible;

(5) Under the protection of inert gas, assemble the negative electrode current collector (carbon foam) adsorbed with metal and the top cover onto the shell to which the molten salt (not solidified) has been added, and then cool naturally to room temperature;

(6) Welding the shell and the top cover by laser welding or argon arc welding to obtain an assembled battery;

(7) The battery is placed in a test furnace, heated to the operating temperature and maintained at a constant temperature, and connected to a battery test system for battery testing.

Example 7

A Li||Bi-Sn liquid metal battery operating at 200°C, characterized by the following steps:

(1) Under the protection of inert gas, weigh 13 g of bismuth particles and 11 g of tin particles and place them in a graphite crucible (inner diameter 56 mm);

(2) Under the protection of inert gas, the graphite crucible is heated to 300° C. on a heating plate and kept at this temperature for 1 hour to melt the metal bismuth and the metal tin to form an alloy; then the crucible is naturally cooled to room temperature, and then the graphite crucible is placed in a stainless steel shell of a matching size;

(3) Under the protection of inert gas, 1.3 g of liquid metal lithium was absorbed by foamed carbon as the negative electrode;

(4) Under the protection of inert gas, 60 g of dried LiBr-LiI-KI-CsI (molar ratio: 9.6-54.3-16.2-19.9) mixed salt was heated and melted, and poured into the aforementioned graphite crucible;

(5) Under the protection of inert gas, assemble the negative electrode current collector (carbon foam) adsorbed with metal and the top cover onto the shell to which the molten salt (not solidified) has been added, and then cool naturally to room temperature;

(6) Welding the shell and the top cover by laser welding or argon arc welding to obtain an assembled battery;

(7) The battery is placed in a test furnace, heated to the operating temperature and maintained at a constant temperature, and connected to a battery test system for battery testing.

Example 8

A Li||Bi-Sn liquid metal battery operating at 220°C is produced by the following steps:

(1) Under the protection of inert gas, weigh 13 g of bismuth particles and 11 g of tin particles and place them in a graphite crucible (inner diameter 56 mm);

(2) Under the protection of inert gas, the graphite crucible is heated to 300° C. on a heating plate and kept at this temperature for 1 hour to melt the metal bismuth and the metal tin to form an alloy; then the crucible is naturally cooled to room temperature, and then the graphite crucible is placed in a stainless steel shell of a matching size;

(3) Under the protection of inert gas, 1.3 g of liquid metal lithium was absorbed by foamed carbon as the negative electrode;

(4) Under the protection of inert gas, 60 g of dried LiCl-LiBr-LiI-KI-CsI (molar ratio: 3.5-9.2-52.4-15.7-19.2) mixed salt was heated and melted, and poured into the aforementioned graphite crucible;

(5) Under the protection of inert gas, assemble the negative electrode current collector (carbon foam) adsorbed with metal and the top cover onto the shell to which the molten salt (not solidified) has been added, and then cool naturally to room temperature;

(6) Welding the shell and the top cover by laser welding or argon arc welding to obtain an assembled battery;

(7) The battery is placed in a test furnace, heated to the operating temperature and maintained at a constant temperature, and connected to a battery test system for battery testing. FIG7 shows a discharge curve of the battery at 220 degrees.

In summary, the present invention introduces rubidium ions/cesium ions into the electrolyte of the liquid metal battery, which greatly reduces the melting point of the electrolyte without sacrificing the stability of the electrolyte, so that the liquid metal battery can operate at a relatively low temperature of 190 to 290 degrees. The lower operating temperature not only greatly reduces the power consumption of the thermal management system, but also brings many benefits to the insulation and corrosion resistance of the battery.

It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. A low-temperature liquid metal battery capable of circularly charging and discharging comprises a shell, and a positive electrode, a negative electrode and an electrolyte which are sealed in the shell, and is characterized in that,

The negative electrode includes lithium metal;

the electrolyte comprises two or more metal halide salts, wherein the metal halide salts comprise lithium halides and also comprise rubidium halides and/or cesium halides, and the melting point of the electrolyte is not more than 300 ℃;

the electrolyte is any combination of the following:

LiBr_20-60-RbBr_80-40；

LiBr_20-60-CsCl_80-40；

LiBr_40-80-CsBr_60-20；

LiI_45-85-CsI_55-15；

LiCl_20-80-KCl_0-30-CsCl_0-40；

LiCl_40-80-KCl_10-30-RbCl_0-20-CsCl_0-40；

LiBr_40-80-KBr_10-30-CsBr_0-40；

LiI_40-80-KI_0-30-CsI_0-40；

LiBr_5-20-LiI_40-80-KI_10-30-CsI_10-40；

LiCl_1-10-LiBr_0-20-LiI_30-70-KI_0-30-CsI_0-40；

Wherein the mole percentages of the components in the electrolyte add up to 100%.

2. The low temperature liquid metal battery of claim 1, wherein the positive electrode is an alloy of two metals of antimony, bismuth, tin, and lead.

3. The low temperature liquid metal battery of claim 2, wherein the positive electrode is any one of:

bi _10-90-Sn_90-10 alloy;

Bi _10-90-Pb_90-10 alloy;

sn _10-90-Pb_90-10 alloy;

Sb _5-50-Pb_95-50 alloy;

wherein the mole percentages of the components in each positive electrode alloy add up to 100%.

4. The low temperature liquid metal battery of claim 1, further comprising a negative current collector that is a foam iron nickel or foam carbon.

5. The preparation method of the low-temperature liquid metal battery capable of being circularly charged and discharged is characterized by comprising the following steps of:

under the protection of inert gas, placing a positive electrode material into a crucible, heating, melting, naturally cooling to form a positive electrode, and placing the crucible into a matched stainless steel shell;

under the protection of inert gas, heating, melting and pouring electrolyte materials into the crucible to form electrolyte; the electrolyte comprises two or more metal halide salts, wherein the metal halide salts comprise lithium halides and also comprise rubidium halides and/or cesium halides, and the melting point of the electrolyte is not more than 300 ℃;

Under the protection of inert gas, absorbing liquid metal lithium by using a negative electrode current collector, assembling the negative electrode current collector absorbed with the metal lithium and a top cover on a shell, and then naturally cooling;

Welding the shell and the top cover to obtain an assembled low-temperature liquid metal battery;

Wherein the electrolyte is any combination of the following:

LiBr_20-60-RbBr_80-40；

LiBr_20-60-CsCl_80-40；

LiBr_40-80-CsBr_60-20；

LiI_45-85-CsI_55-15；

LiCl_20-80-KCl_0-30-CsCl_0-40；

LiCl_40-80-KCl_10-30-RbCl_0-20-CsCl_0-40；

LiBr_40-80-KBr_10-30-CsBr_0-40；

LiI_40-80-KI_0-30-CsI_0-40；

LiBr_5-20-LiI_40-80-KI_10-30-CsI_10-40；

LiCl_1-10-LiBr_0-20-LiI_30-70-KI_0-30-CsI_0-40；

Wherein the mole percentages of the components of each combination add up to 100%.

6. The method of manufacturing a low temperature liquid metal battery according to claim 5, wherein the positive electrode is an alloy formed of two metals of antimony, bismuth, tin, and lead;

Placing the positive electrode material in a crucible for heating and melting, comprising:

each metal making up the alloy is placed in a crucible and heated to melt each metal into an alloy.

7. The method of manufacturing a low temperature liquid metal battery according to claim 6, wherein the alloy is any one of the following:

bi _10-90-Sn_90-10 alloy;

Bi _10-90-Pb_90-10 alloy;

sn _10-90-Pb_90-10 alloy;

Sb _5-50-Pb_95-50 alloy;

wherein the mole percentages of the components in each alloy add up to 100%.

8. As in claim 5

The preparation method of the low-temperature liquid metal battery is characterized in that the negative electrode current collector is foam iron nickel or foam carbon.