Energy storage droplet cell and method of making

Abstract

The application discloses a kind of liquid drop batteries for energy storage and preparation method thereof.The liquid drop batteries for energy storage include the following components: battery shell, top cover, battery lining, positive metal material, electrolyte, conductive porous negative electrode separator, negative metal material and insulating ceramic ring;Wherein: battery shell is provided with battery lining in;The lower part of battery lining is positive metal material;The upper part of positive metal material is electrolyte;Negative metal material is located in conductive porous negative electrode separator and is totally immersed in electrolyte, porous negative electrode separator is in contact with negative metal material and is fixedly connected with top cover;Top cover and battery shell are fixed and insulated by insulating ceramic ring between them.The application proposes a kind of liquid drop batteries for energy storage of brand-new structure, utilizes the selective conduction ion and conductive effect of porous negative electrode separator structure, avoids local short circuit and liquid electrode material dissolution phenomenon in electrolyte in the process that battery is operated at high temperature, improves battery cycle performance.

Description

Technical Field

[0001] This invention belongs to the technical field of energy storage batteries, and in particular relates to a droplet battery for energy storage and its preparation method. Background Technology

[0002] Effectively utilizing renewable energy sources such as solar and wind power is a fundamental way for humanity to solve energy problems. However, solar and wind power are intermittent energy sources, characterized by instability, discontinuity, and significant seasonal variations, resulting in low grid integration efficiency and impacting grid stability. Therefore, developing key technologies for large-scale static energy storage to achieve peak shaving and valley filling, and improve electricity demand response capabilities, is an inevitable trend in the future development of smart grids. Currently, common large-scale static energy storage technologies include lead-acid batteries, lithium-ion batteries, sodium-sulfur batteries, Zebla batteries, flow batteries, and liquid metal batteries. However, in terms of cycle performance and long cycle life, existing technologies cannot fully meet the needs of large-scale grid energy storage. Relatively mature lithium-ion batteries consist of solid positive and negative electrodes, polymer separators, and electrolytes. During charging and discharging, changes in the microstructure of the solid electrodes are inevitable, such as volume expansion, deformation, and dendrite growth, which severely restrict battery cycle performance. Using liquid electrodes can fundamentally solve the performance degradation problem caused by changes in the solid electrode structure, achieving long-life battery operation. The long-term operation of high-temperature sodium-sulfur batteries, Zebra batteries, liquid metal batteries, and room-temperature flow batteries based on liquid design has well demonstrated the important value of liquid electrodes in the field of large-scale energy storage. However, the fabrication of β"-Al2O3 ceramic membranes, which are essential for sodium-sulfur batteries and Zebra batteries, is extremely difficult and prone to brittle fracture, greatly reducing battery life. Liquid metal batteries suffer from low voltage and low energy efficiency, while flow batteries require high-performance membranes and relatively complex battery structures. Therefore, there is an urgent need for new large-scale energy storage technologies that are low-cost, high-efficiency, and long-life. Summary of the Invention

[0003] To address the aforementioned technical problems, the present invention aims to provide a droplet battery for energy storage and its preparation method. By fixing the negative electrode material in a conductive porous negative electrode membrane, direct contact between the positive and negative electrode materials can be avoided, preventing local short circuits at the negative electrode of the battery. At the same time, the loss of the negative electrode due to ionization or dissolution in the electrolyte can also be avoided, thereby improving the battery's energy efficiency.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A droplet battery for energy storage is provided, comprising the following components: a battery casing, a top cover, a battery liner, a positive electrode metal material, an electrolyte, a conductive porous negative electrode separator, a negative electrode metal material, and an insulating ceramic ring; wherein:

[0006] The battery casing is provided with a battery liner;

[0007] The lower part of the battery liner is made of positive electrode metal material;

[0008] The electrolyte is located above the positive electrode metal material;

[0009] The negative electrode metal material is located in the conductive porous negative electrode membrane and is completely immersed in the electrolyte. The porous negative electrode membrane is in contact with the negative electrode metal material and is fixedly connected to the top cover. The top cover is fixed and insulated from the battery casing by an insulating ceramic ring.

[0010] According to the above scheme, it also includes a positive terminal and a negative terminal.

[0011] According to the above scheme, the positive electrode metal material is electrically connected to the battery casing.

[0012] According to the above scheme, when the battery liner material is conductive, the battery casing has a battery liner on both the inner wall and the bottom, or only the inner wall of the battery casing has a battery liner; when the battery liner material is non-conductive, the battery casing has a battery liner on only the inner wall.

[0013] According to the above scheme, the battery casing or top cover is made of stainless steel or Kovar alloy; preferably, the stainless steel is 304 stainless steel, 304L stainless steel, 316 stainless steel or 316L stainless steel; the Kovar alloy is 4J33 Kovar alloy or 4J29 Kovar alloy.

[0014] According to the above scheme, the battery liner material is either graphite or ceramic; the ceramic material is either alumina, magnesium oxide, or boron nitride.

[0015] According to the above scheme, the positive electrode metal material is one or more of aluminum, zinc, gallium, germanium, arsenic, selenium, cadmium, indium, tin, antimony, tellurium, mercury, thallium, lead, and bismuth.

[0016] According to the above scheme, the negative electrode metal material is one or more of alkali metals (lithium, sodium, potassium, rubidium, cesium) or alkaline earth metals (magnesium, calcium, strontium, barium) and their alloys with positive electrode metal elements.

[0017] According to the above scheme, the electrolyte material is a mixture of at least two inorganic metal halide salts. For example, LiCl-KCl, LiCl-LiF, NaCl-CaCl2, LiF-LiCl-LiBr, LiF-LiCl-LiI, NaF-NaCl-NaI, KCl-LiCl-NaCl, LiCl-CaCl2, etc.

[0018] According to the above scheme, the conductive porous negative electrode membrane is made of graphite, metal or conductive ceramic; preferably, the metal is stainless steel, nickel, iron, copper or titanium; the conductive ceramic is titanium nitride or silicon carbide.

[0019] According to the above scheme, the pore size of the conductive porous negative electrode membrane is 5-100 μm, and the porosity is 30-90%.

[0020] According to the above scheme, the insulating ceramic ring is one or more of boron nitride, aluminum nitride, silicon nitride, magnesium oxide, silicon oxide, zirconium oxide, or aluminum oxide.

[0021] A method for preparing the above-mentioned droplet battery for energy storage is provided, wherein the entire process is carried out in an inert atmosphere or vacuum environment, and the specific steps are as follows:

[0022] S1. Place the inner liner into the battery casing and put the positive electrode metal material used in the droplet battery into the battery inner liner;

[0023] S2. Heat the inner liner to the battery's operating temperature, causing the positive electrode metal material to melt into a liquid state and spread all over the bottom. Then stop heating and let it cool naturally to room temperature.

[0024] S3. Thoroughly mix the pre-dried electrolyte raw materials, pre-melt them, and then pour them into the battery liner in step S2.

[0025] S4. Place the negative electrode metal material in the conductive porous negative electrode membrane, and weld the conductive porous negative electrode membrane to the top cover. Then, immerse the negative electrode metal material completely in the molten electrolyte in S3.

[0026] S5. Weld the top cover of the battery to the battery casing using an insulating ceramic ring to obtain the droplet battery.

[0027] According to the above scheme, the water and oxygen content in the preparation process environment is <10ppm.

[0028] According to the above scheme, in step S2, the battery operating temperature is 200-1000℃.

[0029] According to the above scheme, in step S3, the electrolyte pre-melting time is 1-48h.

[0030] The beneficial effects of this invention are as follows:

[0031] 1. The present invention provides a droplet battery for energy storage. By introducing a porous membrane structure at the negative terminal, the negative electrode material is fixed while ions are conducted through the porous structure, avoiding the loss of the negative electrode material due to ionization or dissolution in the electrolyte. This significantly improves the battery cycle efficiency without affecting battery performance. At the same time, through the conductivity of the porous membrane, ions are selectively conducted without affecting battery discharge. This allows the positive electrode metal ions to be reduced to metal droplets and fall back to the bottom of the battery when they come into contact with the porous negative electrode membrane, isolating the direct contact between the positive and negative electrode metal materials. This avoids local short circuits inside the battery and is beneficial to improving battery performance.

[0032] 2. The preparation process of this invention is simple. It isolates the direct contact between the positive and negative electrode metal materials and avoids the loss of the negative electrode material through a simple method, which is beneficial for industrial application. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the liquid droplet battery structure assembled in Embodiment 1 of the present invention.

[0034] Figure 2 This is a schematic diagram of the liquid droplet battery structure assembled in Embodiment 2 of the present invention.

[0035] Figure 3 The battery assembled in Example 1 operates at 50 mA / cm. 2 Circuit density charge-discharge cycle diagram.

[0036] Figure 4 The battery assembled in Example 1 operates at 50 mA / cm. 2 Circuit density, charge-discharge cycle 50 cycles, coulombic efficiency and discharge capacity diagram.

[0037] Figure 5 The battery assembled in Example 1 operates at 100 mA / cm 2 Circuit density charge-discharge cycle diagram.

[0038] Figure 6 The battery assembled in Example 1 operates at 100 mA / cm 2 Circuit density, charge-discharge cycle 50 cycles, coulombic efficiency and discharge capacity diagram.

[0039] in Figure 1 and 2 The winning number is:

[0040] 1-Top cover, 2-Positive and negative terminals, 3-Insulating ceramic ring, 4-Battery liner, 5-Conductive porous negative electrode separator, 6-Negative electrode metal material, 7-Battery casing, 8-Electrolyte, 9-Positive electrode metal material. Detailed Implementation

[0041] The present invention will be further explained and described below with reference to the accompanying drawings and embodiments.

[0042] like Figure 1-2 As shown, this embodiment of the invention provides a droplet battery for energy storage, comprising the following components: a battery casing 7, a top cover 1, a battery liner 4, a positive electrode metal material 9, an electrolyte 8, a conductive porous negative electrode separator 5, a negative electrode metal material 6, and an insulating ceramic ring 3; wherein:

[0043] A battery liner 4 is provided inside the battery casing 7;

[0044] The lower part of the battery liner 4 is a positive electrode metal material 9;

[0045] The electrolyte 8 is located above the positive electrode metal material 9;

[0046] The negative electrode metal material 6 is located in the conductive porous negative electrode membrane 5 and is completely immersed in the electrolyte 8. The porous negative electrode membrane 5 is in contact with the negative electrode metal material 6 and is fixedly connected to the top cover 1. The top cover 1 is fixed and insulated from the battery casing 7 by an insulating ceramic ring 3.

[0047] In one embodiment, a positive terminal and a negative terminal 2 are also included.

[0048] In one embodiment, the positive electrode metal material 9 is electrically connected to the battery casing 7.

[0049] In one embodiment, when the battery liner 4 is made of conductive material, the battery housing 7 is provided with battery liner 4 on both the inner wall and the bottom, or only the inner wall of the battery housing 7 is provided with battery liner 4; when the battery liner 4 is not made of conductive material, the battery housing 7 is provided with battery liner 4 only on the inner wall.

[0050] In one embodiment, the battery casing 7 or top cover 1 is made of stainless steel or Kovar alloy; in a preferred embodiment, the stainless steel is 304 stainless steel, 304L stainless steel, 316 stainless steel or 316L stainless steel; the Kovar alloy is 4J33 Kovar alloy or 4J29 Kovar alloy.

[0051] In one embodiment, the battery liner 4 is made of either graphite or ceramic material; in a preferred embodiment, the ceramic material is one of alumina, magnesium oxide, or boron nitride.

[0052] In one embodiment, the positive electrode metal material 9 is one or more of aluminum, zinc, gallium, germanium, arsenic, selenium, cadmium, indium, tin, antimony, tellurium, mercury, thallium, lead, and bismuth.

[0053] In one embodiment, the negative electrode metal material 6 is one or more of an alkali metal (lithium, sodium, potassium, rubidium, cesium) or an alkaline earth metal (magnesium, calcium, strontium, barium) and its alloy with the positive electrode metal element.

[0054] In one embodiment, the electrolyte 8 material is a mixture of at least two inorganic metal halide salts. For example, LiCl-KCl, LiCl-LiF, NaCl-CaCl2, LiF-LiCl-LiBr, LiF-LiCl-LiI, NaF-NaCl-NaI, KCl-LiCl-NaCl, LiCl-CaCl2, etc.

[0055] In one embodiment, the conductive porous negative electrode membrane 5 is made of graphite, metal, or conductive ceramic; in a preferred embodiment, the metal is stainless steel, nickel, iron, copper, or titanium; and the conductive ceramic is titanium nitride or silicon carbide.

[0056] In one embodiment, the conductive porous negative electrode membrane 5 has a pore size of 5–100 μm and a porosity of 30–90%.

[0057] In one embodiment, the insulating ceramic ring 3 is one or more of boron nitride, aluminum nitride, silicon nitride, magnesium oxide, silicon oxide, zirconium oxide, or aluminum oxide.

[0058] The following is a specific example:

[0059] Example 1

[0060] A droplet battery for energy storage is provided, the preparation of which includes the following steps:

[0061] S1. In an argon atmosphere, place the graphite liner in a 316 stainless steel battery casing and weigh 7g of lead particles as the positive electrode material and place them in the graphite liner; wherein the graphite liner is set on the inner wall and bottom of the battery casing.

[0062] S2. Heat the graphite liner to 410°C, so that the positive electrode metal material melts into a liquid state and spreads all over the bottom of the graphite liner, and then remove it and let it cool naturally.

[0063] S3. Mix the pre-dried LiCl-KCl electrolyte raw materials thoroughly at a molar ratio of 58:42. Take 40g of the mixed powder and place it in a crucible container for pre-melting for 4 hours. Then pour it into a graphite liner.

[0064] S4. Place 15g of lithium-lead alloy into a stainless steel conductive porous negative electrode membrane, and weld the porous membrane to the 316 stainless steel top cover. Then immerse the negative electrode metal completely in the molten electrolyte. The conductive porous negative electrode membrane has a pore size of 30μm and a porosity of 40%.

[0065] S5. Weld the battery top cover to the 316 stainless steel battery casing and secure it with a boron nitride insulating ceramic ring; fix the positive and negative terminals of the battery and lead out the terminals to obtain the packaged battery cell, i.e., the droplet battery, as shown in the structural diagram. Figure 1 As shown.

[0066] The resulting droplet battery was heated to 410°C and held at that temperature for 24 hours, then subjected to a 50 mA / cm² temperature control. 2 The circuit density is used to activate the battery through charge-discharge cycles. The charging cutoff voltage is set to 1.8V, the discharging cutoff voltage to 0.2V, and the charge / discharge current density to 50mA / cm². 2 .

[0067] Test results are as follows Figure 2 , Figure 3 As shown, the battery exhibits a good voltage plateau during charge and discharge, and after 50 cycles, it demonstrates an average coulombic efficiency of 97.07% per cycle.

[0068] The resulting droplet battery was heated to 410°C and held at that temperature for 24 hours, then subjected to a 50 mA / cm² temperature control. 2 The circuit density is used to activate the battery through charge-discharge cycles. The charging cutoff voltage is set to 1.8V, the discharging cutoff voltage to 0.2V, and the charge / discharge current density to 100mA / cm². 2 .

[0069] Test results are as follows Figure 4 , Figure 5 As shown, the battery exhibits a good voltage plateau during charge and discharge, and after 50 cycles, it demonstrates an average coulombic efficiency of 97.73% per cycle.

[0070] Example 2

[0071] A droplet battery for energy storage is provided, the preparation of which includes the following steps:

[0072] S1. In an argon atmosphere, place the alumina liner inside a 316 stainless steel battery casing and weigh 7g of tin granules as the positive electrode material and place them inside the alumina liner; wherein the alumina liner is located on the inner wall of the battery casing.

[0073] S2. Heat the alumina liner to 300°C, so that the positive electrode metal material melts into a liquid state and spreads to the bottom of the battery casing, then remove it and let it cool naturally.

[0074] S3. Mix the pre-dried LiCl-KCl electrolyte raw materials thoroughly at a molar ratio of 58:42. Take 40g of the mixed powder and place it in a crucible container for pre-melting for 4 hours. Then pour it into the alumina liner.

[0075] S4. Place 15g of lithium-tin alloy into a stainless steel conductive porous negative electrode membrane, and weld the porous membrane to the 316 stainless steel top cover. Then immerse the negative electrode metal completely in the molten electrolyte. The conductive porous negative electrode membrane has a pore size of 20μm and a porosity of 35%.

[0076] S5. Weld the battery top cover to the 316 stainless steel battery casing and secure it with a boron nitride insulating ceramic ring; fix the positive and negative terminals of the battery and lead out the terminals to obtain the packaged battery cell, i.e., the droplet battery, as shown in the structural diagram. Figure 2 As shown.

[0077] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A droplet battery for energy storage, characterized by, It includes the following components: battery casing, top cover, battery liner, positive electrode metal material, electrolyte, conductive porous negative electrode separator, negative electrode metal material, and insulating ceramic ring; wherein: The battery casing is provided with a battery liner; The lower part of the battery liner is a positive electrode metal material; the liner is heated to the battery's operating temperature, causing the positive electrode metal material to melt into a liquid state and spread all over the bottom, and then heating is stopped and allowed to cool naturally to room temperature; The positive electrode metal material is electrically connected to the battery casing; The electrolyte is located above the positive electrode metal material; The negative electrode metal material is located in a conductive porous negative electrode membrane and is completely immersed in the electrolyte. The porous negative electrode membrane is in contact with the negative electrode metal material and is fixedly connected to the top cover. The top cover is fixed and insulated from the battery casing by the insulating ceramic ring. The conductive porous negative electrode membrane has a pore size of 20~30 μm and a porosity of 30~40%.

2. The droplet battery for energy storage of claim 1, wherein, When the battery liner material is conductive, the battery housing has a battery liner on both the inner wall and the bottom, or only the inner wall of the battery housing has a battery liner; when the battery liner material is non-conductive, the battery housing has a battery liner on only the inner wall.

3. The droplet battery for energy storage according to claim 1, characterized in that, It also includes the positive terminal and the negative terminal.

4. The droplet battery for energy storage according to claim 1, characterized in that, The battery casing or top cover is made of either stainless steel or Kovar alloy. The battery liner material is one of graphite or ceramic material; the conductive porous negative electrode membrane material is one of graphite, metal or conductive ceramic. The insulating ceramic ring is one or more of boron nitride, aluminum nitride, silicon nitride, magnesium oxide, silicon oxide, zirconium oxide, or aluminum oxide.

5. The droplet battery for energy storage according to claim 1, characterized in that, The positive electrode metal material is one or more of the following: aluminum, zinc, gallium, germanium, arsenic, selenium, cadmium, indium, tin, antimony, tellurium, mercury, thallium, lead, and bismuth. The negative electrode metal material is one or more of alkali metals or alkaline earth metals and their alloys with positive electrode metal elements. The electrolyte material is a mixture of at least two inorganic metal halide salts.

6. A method for preparing a droplet battery for energy storage according to any one of claims 1-5, characterized in that, The entire preparation process takes place in an inert atmosphere or vacuum environment, and the specific steps are as follows: S1. Place the inner liner into the battery casing and put the positive electrode metal material used in the droplet battery into the battery inner liner; S2. Heat the inner liner to the battery's operating temperature, causing the positive electrode metal material to melt into a liquid state and spread all over the bottom. Then stop heating and let it cool naturally to room temperature. S3. Thoroughly mix the pre-dried electrolyte raw materials, pre-melt them, and then pour them into the battery liner in step S2. S4. Place the negative electrode metal material in the conductive porous negative electrode membrane, and weld the conductive porous negative electrode membrane to the top cover. Then, immerse the negative electrode metal material completely in the molten electrolyte in S3. S5. Weld the top cover of the battery to the battery casing using an insulating ceramic ring to obtain the droplet battery.

7. The preparation method according to claim 6, characterized in that, The water and oxygen content in the preparation process environment is both <10ppm.

8. The preparation method according to claim 6, characterized in that, In step S2, the battery operating temperature is 200-1000 ℃; in step S3, the electrolyte pre-melting time is 1-48h.

Images