Liquid metal battery and assembly method thereof

Abstract

A liquid metal battery and an assembly method thereof, belonging to the technical field of liquid metal batteries, overcomes the defects of the prior art that the corrosion of high-temperature steam destroys the sealing of the battery, causes the battery sealing insulation to fail, and reduces the battery operating life. The liquid metal battery of the present invention comprises a shell, a conductive crucible and a protective device, wherein the protective device comprises more than two layers of baffles, and an insulating material is arranged between adjacent baffles; the conductive crucible is arranged in the shell, and the protective device is used to close the conductive crucible opening.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid metal batteries, and in particular relates to a liquid metal battery and an assembly method thereof. Background Art

[0002] With the imbalance of global energy supply and the increasing depletion of traditional energy represented by fossil fuels, countries are paying more and more attention to energy security. New energy represented by photovoltaic and wind power has received a lot of human and material investment, and the global installed capacity of renewable energy and the proportion of energy are rising. However, new energy has the characteristics of discontinuity. The power generation end and the demand end cannot match in time, and the power generation of new energy is volatile. When a large number of new energy power stations are directly connected to the power grid, this instability will have a serious impact on the power grid, ranging from unstable voltage to overload and burnout of power grid equipment, leading to even paralysis of the power grid. The power generation end and the demand end cannot match in space either, and the electricity generated by the power station needs storage equipment. The introduction of energy storage devices can eliminate the shortcomings of new energy and play an important role in shaving peaks and balancing valleys, improving the contradiction between power supply and demand, and improving the safety and stability of the power grid.

[0003] At present, energy storage technologies include mechanical energy storage, electrical energy storage, chemical energy storage and electrochemical energy storage. Electrochemical energy storage has become the main direction in the field of energy storage due to its advantages such as high energy density, low maintenance cost, flexible and convenient installation, and easy large-scale networking. Traditional electrochemical energy storage includes lead-acid batteries, lithium-ion batteries, flow batteries, sodium-sulfur batteries, etc., but traditional batteries have problems such as high preparation and operation costs and low cycle life. It is urgent to develop a battery system suitable for large-scale energy storage.

[0004] In 2006, Professor Sadoway of the Massachusetts Institute of Technology (MIT) proposed the concept of large-scale energy storage using all-liquid metal batteries. Liquid metal batteries (LMBs) are composed of two layers of liquid metal electrodes and molten electrolyte. Both the electrodes and the electrolyte are liquid, and the components are immiscible and self-stratified due to different densities. The all-liquid battery structure gives liquid metal batteries the advantages of high rate, low cost, long cycle life, and easy amplification, and has broad application prospects in the field of large-scale energy storage.

[0005] However, liquid metal batteries also have their disadvantages. In order to keep the electrodes and electrolytes in a liquid state, the battery needs to work at high temperatures, and the battery components are very sensitive to water, oxygen, etc. The assembly and operation of the battery must be carried out under protective gas or vacuum. At high temperatures, the fully liquid positive and negative electrodes of the battery and the high-temperature vapor of the electrolyte have a strong corrosive effect on the battery sealing insulation and battery casing, destroying the battery sealing, causing the battery sealing insulation to fail, leading to the entry of air and moisture, and reducing the battery life. Therefore, it is of practical significance to develop a new battery casing protection device to meet the needs of liquid metal batteries for corrosion protection, sealing, and protection of the battery casing when they work for a long time at high temperatures. Summary of the invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defects in the prior art that the corrosion of high-temperature steam destroys the battery sealing, causes the battery sealing insulation to fail, and reduces the battery operating life, thereby providing a liquid metal battery and its assembly method.

[0007] To this end, the present invention provides the following technical solutions.

[0008] In one aspect, the present invention provides a liquid metal battery, comprising a shell, a conductive crucible and a protective device, wherein the protective device comprises two or more baffles, and a heat insulating material is arranged between adjacent baffles;

[0009] The conductive crucible is arranged in the shell, and the protective device is used to close the conductive crucible opening.

[0010] Furthermore, it also includes a negative electrode lead rod, and the protection device is provided with a through hole for the negative electrode lead rod to pass through.

[0011] Furthermore, the size of the protection device is larger than the size of the conductive crucible opening and smaller than the size of the interior of the shell.

[0012] Furthermore, at least one of the following conditions is met:

[0013] (1) The material of the protective device is insulating ceramic material;

[0014] Preferably, the insulating ceramic material includes at least one of aluminum oxide, zirconium oxide or yttrium oxide;

[0015] (2) The thermal conductivity of the thermal insulation material is ≤0.23 W / m·K. Preferably, the thermal insulation material is a polyurethane board, a rock wool board or a glass wool board.

[0016] Furthermore, a sealing material is provided to seal the gap between the protection device and the shell and / or the gap between the through hole of the protection device and the negative electrode lead rod;

[0017] Preferably, the sealing material is polyurethane or high temperature resistant inorganic silicate glue.

[0018] Furthermore, the protection device includes two layers of baffles, each layer of the baffles has a thickness of 3 to 8 mm, and the interval between the two layers of the baffles is 3 to 8 mm.

[0019] Furthermore, it also includes an upper cover and a sealing insulating member;

[0020] The upper cover is provided with a through hole for the negative electrode lead rod to pass through, and the sealing insulating member is used to seal the gap between the upper cover and the negative electrode lead rod.

[0021] Furthermore, a convex circular ring is provided on the bottom surface of the upper cover, and a concave circular groove is provided at a corresponding position of the shell.

[0022] In another aspect, the present invention provides a method for assembling a liquid metal battery, comprising the following steps:

[0023] Step 1, heat and melt the positive electrode material and pour it into a conductive crucible, heat the conductive crucible, and pour in a molten electrolyte; press the negative electrode current collector into the molten electrolyte, so that the upper surface of the negative electrode current collector is flush with the liquid surface of the molten electrolyte, stop heating, and the molten electrolyte cools and solidifies to fix the negative electrode current collector;

[0024] The negative electrode current collector is connected to a negative electrode lead rod and adsorbs negative electrode material;

[0025] Preferably, the negative electrode current collector is located in the center;

[0026] Step 2, placing the conductive crucible into the shell;

[0027] Step 3, placing the protective device on the conductive crucible, passing the negative electrode lead rod through the through hole on the protective device, and sealing the gap with a sealing material;

[0028] Step 4: Install and fix the top cover.

[0029] Furthermore, the assembly process was carried out in a glove box with an inert gas atmosphere with an oxygen and water content of less than 0.1 ppm to prevent oxygen and water in the air from reacting with and adsorbing the electrodes and electrolytes.

[0030] The negative electrode current collector is located in the center of the battery to avoid contact with the conductive crucible.

[0031] Preparation of materials before assembly of liquid metal batteries:

[0032] (1) Heat and melt the negative electrode material and fill it into the negative electrode current collector, and connect the negative electrode lead rod;

[0033] (2) Preparation of electrolyte powder: Weighing electrolyte materials, mixing and sintering in an atmosphere furnace in steps to remove water from the electrolyte and melt the electrolyte to make the electrolyte mix evenly. After sintering the electrolyte, take out the bulk electrolyte and grind it into powder using a ball mill;

[0034] (3) Preparation of positive electrode materials: Weigh the positive electrode metal in a glove box, and mix and stir the alloy evenly. Heat the positive electrode metal or alloy in a heating furnace until it melts to make the positive electrode components uniform.

[0035] The method to determine whether the protective device needs to be replaced is to observe the corrosion marks on the sealing insulating parts of the battery cover. When the protective device fails, lithium will escape from the conductive crucible to the battery cover, and non-smooth corrosion marks will appear on the surface of the sealing insulating parts. The method to replace the protective device is: open the battery cover, remove the sealing material with a blade, take out the old protective device, pass the negative electrode lead rod through the through hole on the new protective device, cover the protective device on the conductive crucible, and use the sealing material to re-seal the gap between the protective device and the negative electrode lead rod and the shell. The sealing position is inside and on the gap.

[0036] The technical solution of the present invention has the following advantages:

[0037] 1. The liquid metal battery provided by the present invention includes a shell, a conductive crucible and a protective device, wherein the protective device includes more than two layers of baffles, and insulating materials are arranged between adjacent baffles; the conductive crucible is arranged in the shell, and the protective device is used to close the conductive crucible opening.

[0038] The protective device directly covers the conductive crucible to isolate the battery material, high-temperature steam and battery shell in the conductive crucible, which can significantly reduce the corrosion of the battery shell and seals by the high-temperature steam inside the crucible, ensure the sealing of the battery, and thus increase the operating life of the battery.

[0039] The protective device also has the advantage of heat insulation. The adjacent baffles are filled with heat-insulating materials, and the main form of heat transfer from the conductive crucible to the upper part of the battery is gas → solid → gas, which effectively achieves the purpose of heat insulation.

[0040] 2. The baffle and gap sealing material of the present invention are both made of insulating materials. When the battery of the present invention is used, the negative electrode lead rod, the battery shell, and the conductive crucible will not form a conductive channel, thereby achieving the purpose of insulation.

[0041] 3. The gap sealing material of the present invention is made of high temperature resistant material, which fills the gap between the protective device, the negative electrode lead rod and the battery shell, and blocks the high temperature corrosive steam in the conductive crucible from overflowing upward, thus achieving a sealing effect. Under the joint action of the battery shell and the protective device, the battery sealing is greatly improved compared with the traditional liquid metal battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 It is a schematic diagram of the structure of a liquid metal battery;

[0044] Figure 2 It is an enlarged schematic diagram of the protection device structure.

[0045] Reference numerals:

[0046] 1-negative electrode lead rod; 2-sealing insulating member; 3-upper cover, 4-protective gas; 5-shell, 5.1-concave circular groove, 5.2-convex circular ring; 6-nut; 7-gasket; 8-nut; 9-negative electrode current collector; 10-negative electrode material; 11-electrolyte; 12-positive electrode material; 13-conductive crucible; 14-sealing material; 15-protective device; 15.1-upper baffle; 15.2-lower baffle; 16-insulating material. DETAILED DESCRIPTION

[0047] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0048] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0049] Example 1

[0050] This embodiment provides a liquid metal battery, such as Figure 1 , Figure 2 As shown, it includes a shell 5, a conductive crucible 13 and a protective device 15, the protective device 15 includes an upper baffle 15.1 and a lower baffle 15.2, and an insulating material 16 is arranged between the upper baffle 15.1 and the lower baffle 15.2. The conductive crucible 13 is arranged in the shell 5, and the protective device 15 is used to close the opening of the conductive crucible 13. The shape of the protective device 15 is consistent with the cross-section of the inner cavity of the shell 5, and the size is slightly smaller than the shell 5, and larger than the size of the opening of the conductive crucible 13. The conductive crucible 13 is made of metal and is used to hold electrode materials and electrolytes.

[0051] The thickness of the upper baffle plate 15.1 is 5 mm, the thickness of the lower baffle plate 15.2 is 5 mm, and the thickness of the heat insulating material 16 is 5 mm. In this embodiment, the heat insulating material 16 is a polyurethane plate with a thermal conductivity of 0.018 W / m·K.

[0052] The liquid metal battery further includes a negative electrode lead rod 1, and a through hole for the negative electrode lead rod 1 to pass through is provided on the protection device 15. The material of the protection device 15 is an insulating ceramic material. In this embodiment, the insulating ceramic material is alumina.

[0053] The gap between the protective device 15 and the shell 5 and the gap between the through hole of the protective device 15 and the negative electrode lead rod 1 are sealed by a sealing material 14. In this embodiment, the sealing material 14 is a high temperature resistant inorganic silicate adhesive (Xinwei S525 inorganic silicate adhesive).

[0054] The liquid metal battery further comprises an upper cover 3 and a sealing insulating member 2; the upper cover 3 is provided with a through hole for the negative electrode lead rod 1 to pass through, and the sealing insulating member 2 is used to seal the gap between the upper cover 3 and the negative electrode lead rod 1. A convex circular ring 5.2 is provided on the bottom surface of the upper cover 3, and a concave circular groove 5.1 is provided at a corresponding position of the shell 5. The upper cover 3 and the shell 5 are tightened by a nut 6, a nut 8 and a gasket 7.

[0055] The protective gas 4 is arranged in the space between the protective device 15 and the upper cover.

[0056] Example 2

[0057] This embodiment provides a method for assembling a liquid metal battery. The liquid metal battery in this embodiment is a Li||Bi liquid metal battery operating at 420° C. The shell is cylindrical, and the conductive crucible 13 is cylindrical. The assembly method includes the following steps:

[0058] (1) Under the protection of inert gas, foamed iron nickel is used as the negative electrode current collector 9 to adsorb 0.136 g of molten lithium of the negative electrode material 10. After the negative electrode material lithium is adsorbed, the negative electrode lead rod is connected to the negative electrode current collector, and the assembled negative electrode current collector is set aside for use.

[0059] (2) Preparation of electrolyte 11: Under inert gas protection, weigh 20 g of dry LiCl-LiBr-KBr (molar ratio 33:29:38) mixed salt, heat it at 150°C for 20 hours and at 290°C for 40 hours in a vacuum furnace to remove moisture, and then melt it at 550°C in an Ar atmosphere for 6 hours.

[0060] (3) Preparation of positive electrode material 12: Under the protection of inert gas, 1.299 g of bismuth particles were weighed and placed in a graphite crucible. The graphite crucible was heated to 350° C. and kept warm for 1 hour to melt the metallic bismuth into liquid state, and then naturally cooled to room temperature.

[0061] (4) Under the protection of inert gas, reheat the graphite crucible, pour the molten positive electrode metal into the conductive crucible, heat the electrolyte 11 and pour the liquid electrolyte into the conductive crucible containing liquid bismuth, and press the negative electrode current collector adsorbing the negative electrode material into the molten electrolyte.

[0062] (5) Under the protection of inert gas, place the conductive crucible 13 into the shell.

[0063] (6) Under the protection of inert gas, the protection device 15 is placed on the conductive crucible 13, the negative electrode lead rod 1 passes through the middle through hole, and the top and inside of the gap are sealed with a gap sealing material.

[0064] (7) Under the protection of inert gas, put on the upper cover and tighten the upper cover and the battery metal shell with screws, and the liquid metal battery is prepared.

[0065] In this embodiment, the high-temperature steam in the conductive crucible 13 cannot pass through the protective device 15, and the protective device 15 plays a role of sealing and corrosion prevention. Under the action of low thermal conductivity ceramics and thermal insulation materials, the main heat conduction mode from the inside of the conductive crucible 13 to the outside is gas→solid→gas, which effectively achieves the purpose of thermal insulation.

[0066] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A liquid metal battery, characterized in that: It includes a shell, a conductive crucible, a negative electrode lead rod and a protective device, wherein the protective device includes more than two layers of baffles, and a heat insulating material is arranged between adjacent baffles; The conductive crucible is arranged in the housing, and the protective device is used to seal the conductive crucible opening; The material of the protection device is insulating ceramic material; The protection device is provided with a through hole for the negative electrode lead rod to pass through; The gap between the protection device and the shell and / or the gap between the through hole of the protection device and the negative electrode lead rod are sealed by a sealing material; Also includes an upper cover and a sealing insulating member; The upper cover is provided with a through hole for the negative electrode lead rod to pass through, and the sealing insulating member is used to seal the gap between the upper cover and the negative electrode lead rod.

2. The liquid metal battery according to claim 1, characterized in that: The size of the protection device is larger than the size of the conductive crucible opening and smaller than the size of the interior of the shell.

3. The liquid metal battery according to claim 1, characterized in that: At least one of the following conditions is met: (1) The insulating ceramic material includes at least one of aluminum oxide, zirconium oxide or yttrium oxide; (2) The thermal conductivity of the thermal insulation material is ≤0.23 W / m·K.

4. The liquid metal battery according to claim 3, characterized in that: The thermal insulation material is a polyurethane board, a rock wool board or a glass wool board.

5. The liquid metal battery according to claim 1, characterized in that: The sealing material is polyurethane or high temperature resistant inorganic silicate glue.

6. The liquid metal battery according to any one of claims 1 to 5, characterized in that: The protective device comprises two layers of baffles, each layer of the baffles has a thickness of 3-8 mm, and the interval between the two layers of the baffles is 3-8 mm.

7. The liquid metal battery according to claim 1, characterized in that: A convex circular ring is arranged on the bottom surface of the upper cover, and a concave circular groove is arranged at a corresponding position of the shell.

8. A method for assembling a liquid metal battery according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1, heat and melt the positive electrode material and pour it into a conductive crucible, heat the conductive crucible, and pour in a molten electrolyte; press the negative electrode current collector into the molten electrolyte, so that the upper surface of the negative electrode current collector is flush with the liquid surface of the molten electrolyte, stop heating, and the molten electrolyte cools and solidifies to fix the negative electrode current collector; The negative electrode current collector is connected to a negative electrode lead rod and adsorbs negative electrode material; Step 2, placing the conductive crucible into the shell; Step 3, placing the protective device on the conductive crucible, passing the negative electrode lead rod through the through hole on the protective device, and using a sealing material to seal the gap between the protective device and the shell and / or the gap between the through hole of the protective device and the negative electrode lead rod; Step 4: Install and fix the top cover.

9. The method for assembling a liquid metal battery according to claim 8, characterized in that: The negative electrode current collector is located at the exact center.

10. The method for assembling a liquid metal battery according to claim 8 or 9, characterized in that: The assembly process was carried out in a glove box filled with an inert gas with oxygen and water content less than 0.1 ppm respectively.

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