CN106972174B - A kind of double-layer negative electrode current collector for liquid metal battery and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of energy storage batteries, and relates to a double-layer negative electrode current collector for a liquid metal battery, which comprises an electrode rod, a foamed alloy A impregnated with lithium and a foamed alloy B not impregnated with lithium. A and foam alloy B are coaxially sleeved on the bottom of the electrode rod in sequence from top to bottom, and the foam alloy A and foam alloy B are fixed on the bottom of the electrode rod through the nut arranged on the upper part of foam alloy A and the nut in the bottom groove of foam alloy B. At the bottom of the electrode rod, the nut, foam alloy A and foam alloy B are all closely attached. The invention also discloses a preparation method of the above-mentioned double-layer negative electrode current collector. The double-layer negative electrode current collector of the present invention can effectively fix the foam alloy, the structure can be mechanically processed on a large scale, the assembly is simple, and the processing precision is controllable, which helps to improve the morphology consistency of the negative electrode current collector structure of the battery.

Description

A kind of double-layer negative electrode current collector for liquid metal battery and preparation method thereof

technical field

The invention belongs to the technical field of energy storage batteries, and relates to a double-layer negative electrode current collector for a liquid metal battery and a preparation method thereof, which can improve the morphology difference of the negative electrode current collector of the liquid metal battery and the consistency of the prepared battery performance. .

Background technique

Liquid metal battery is a new type of secondary battery for grid-level energy storage applications. Its monomer is mainly composed of positive electrode, negative electrode, electrolyte and battery shell. The negative electrode of the battery is generally a simple substance or alloy of alkali metal or alkaline earth metal, and the positive electrode is generally a transition metal simple substance, alloy, or other compound that can form an alloy with the negative electrode and has a certain potential difference with the negative electrode. The electrolyte is an inorganic salt corresponding to the negative electrode metal or a mixture thereof. When the battery is in operation, its metal electrodes and inorganic salt electrolyte melt into a liquid state at high temperature, and automatically stratify according to the difference in density. During discharge, the negative metal loses electrons and does work through an external circuit. After the negative electrode metal is ionized, it migrates to the positive electrode through the molten salt and alloys with the positive electrode metal. When charging, the battery performs the reverse process. Through the above-mentioned alloying and de-alloying processes, the liquid metal battery can complete the storage and release of electrical energy and realize energy exchange with the outside.

The negative electrode material inside the liquid metal battery is a high-temperature molten metal with good fluidity, and the battery shell is generally made of metal or alloy structure, so the contact between the two will inevitably cause a short circuit of the battery. That is to say, it is necessary to design a structure that can constrain the molten metal from contact with the battery case; the confinement structure needs to have sufficient contact area with molten lithium, easy installation, standardized production, and good consistency In addition, the negative electrode current collector is a protruding structure inside the battery and needs to have good physical stability to avoid it coming into contact with the shell or the positive electrode material inside the battery, and to provide a stable current.

At present, liquid metal batteries have not yet been industrialized; some of the existing patents use boron nitride ceramic tubes to block the contact between the negative electrode material of the battery and the casing, but this structure will increase the weight of the battery on the one hand, and on the other hand, the negative electrode material and the negative electrode The contact area of the current collector is limited, and the reaction rate is severely restricted; some patents propose to use foam alloys to bind the negative electrode material, which can perfectly solve the problem of the negative electrode material restraint and greatly improve the reaction rate of the battery, but the foam alloy cannot be combined with the negative electrode material. The negative electrode current collector rod is welded. Therefore, at present, most of the foam alloys are fixed by hand using iron wires to penetrate the foam alloys, so that the size, orientation and lower end of the prepared battery holes are inconsistent, resulting in the prepared battery. The morphological consistency of the negative current collector is poor. In addition, for a half-discharged battery, every time the foam alloy is filled with lithium, a part of lithium needs to be thrown out to ensure that the discharge capacity is within the allowable range (generally 20% to 50%), but there are two problems in manually throwing away lithium. : First, the hardness of the foamed alloy is very low at high temperature, and it is easy to cause stress damage to the foamed alloy during the lithium rejection process. It is well known that the consistency of the performance of the battery cells is very important for the grouping and systematization of the battery. Therefore, this structure cannot be used in the industrial production of liquid metal batteries.

Due to the above defects and deficiencies, there is an urgent need to make further improvements and improvements in this field, and to design a negative electrode current collector, which can solve the problems of large differences in morphology of negative electrode current collectors in liquid metal batteries and inconsistency in the performance of prepared batteries. .

SUMMARY OF THE INVENTION

In view of the above defects or improvement needs of the prior art, the present invention provides a double-layer negative electrode current collector for a liquid metal battery and a preparation method thereof. The method of fixing the foam alloy by using a nut, combined with the double-layer foam alloy structure, can effectively fix At the same time, the foamed alloy improves the quality and morphology consistency of the negative electrode current collector of the battery.

In order to achieve the above object, according to one aspect of the present invention, a double-layer negative electrode current collector for a liquid metal battery is provided, characterized in that it includes an electrode rod, a foamed alloy A impregnated with lithium and a lithium-unimpregnated alloy. foam alloy B,

Wherein, the foam alloy A and foam alloy B are arranged coaxially, with threaded through holes in the middle, the inner diameter of the threaded through holes of the foam alloy A and the threaded through holes of the foam alloy B are the same, and the foam alloy B There is also a groove coaxially arranged with the threaded through hole at the bottom, the groove is used to install the nut, the shape of the groove matches the shape of the above-mentioned nut, and the inner diameter of the groove is larger than the inner diameter of the threaded through hole, The foamed alloy A and the foamed alloy B are coaxially sleeved on the bottom of the electrode rod from top to bottom, and the foamed alloy A and foam Alloy B is fixed on the bottom of the electrode rod, and the nut, foamed alloy A and foamed alloy B are in close contact.

Specifically, by means of threaded connection, a firm connection between the electrode rod and the foamed alloy can be achieved, and the consistency of the appearance can be ensured. The negative electrode current collector is prepared by using a foam alloy impregnated with lithium and a foam alloy not impregnated with lithium. The step of rejecting lithium in the later stage can ensure the consistency of the performance of the battery thus prepared.

Further preferably, the foamed alloy A impregnated with lithium is formed by soaking the foamed alloy in high-temperature molten lithium until the absorption is saturated, and then cooling.

Preferably, both the foamed alloy A and the foamed alloy B are made of iron-nickel foamed alloy, iron foamed alloy, nickel foamed alloy, cobalt-nickel foamed alloy or nickel-chromium foamed alloy, and the nuts are made of stainless steel. Many tests have shown that iron-nickel foam alloys, iron foam alloys, nickel foam alloys, cobalt-nickel foam alloys, nickel-chromium foam alloys and stainless steel have good corrosion resistance, and they can be used to prepare electrode current collectors. Corrosion caused by the environment prolongs the service life of liquid metal batteries.

Preferably, the lower end of the electrode rod is provided with a thread, and the thread is used for matching with the threaded through holes on the nut and the foam alloy A and the foam alloy B. Through the screw connection, the foam alloy can be effectively fixed, and the above structure can be mechanically processed on a large scale, and the assembly is simple and the processing precision is controllable, which helps to improve the morphology consistency of the negative electrode current collector structure of the battery.

Preferably, the bottom of the nut at the bottom of the foam alloy B is flush with the bottom end of the electrode rod.

In order to achieve the above object, according to one aspect of the present invention, there is provided a method for preparing a double-layer negative electrode current collector for a liquid metal battery as described above, which is characterized by comprising the following steps:

S1. Prepare a mold to prepare a foamed alloy with the same shape as the foamed alloy A, and a foamed alloy B with the same shape as the foamed alloy A and a groove at the bottom for use;

S2. Put the foamed alloy with the same shape as the foamed alloy A obtained in step S1 into high-temperature molten lithium and soak it until the foamed alloy is absorbed to a saturated state, and then take out and cool to obtain the foamed alloy A soaked with lithium;

S3. Put the bottom nut, foam alloy B, foam alloy A and the nut on the upper part of foam alloy A on the electrode rod in sequence from bottom to top, and rotate and tighten them one by one from bottom to top until the contact surfaces between them are in close contact. Double layer anode current collector.

Further preferably, the nut on the bottom after being tightened in step S3 is located in the groove at the bottom of the foam alloy B, and the lower surface of the nut in the bottom groove and the lower surface of the electrode rod are at the same level.

In general, compared with the prior art, the above technical solutions conceived by the present invention have the following advantages and beneficial effects:

(1) The structure design of the double-layer negative electrode current collector of the present invention adopts the method of fixing the foam alloy with a nut, which can effectively fix the foam alloy. At the same time, the structure can be mechanically processed on a large scale, and the assembly is simple and the processing accuracy is controllable, which helps to improve the negative electrode of the battery. Morphological consistency of current collector structures.

(2) The present invention adopts a double-layer foam alloy structure, one layer is impregnated with lithium, and the other is not impregnated with lithium, which can precisely control the initial discharge degree of the liquid metal battery, which not only enables the positive and negative electrodes of the battery to be processed at the same time, and improves the production efficiency; The matching records in the assembly process are avoided, and the possibility of inconsistent charging inside the battery caused by misoperation is avoided; at the same time, the stress damage of the foam and the inconsistent lithium rejection caused by the manual lithium rejection process are reduced. Multi-angle action greatly improves the assembly process of the battery and improves the consistency of the battery. And foam alloy, stainless steel and other materials have good corrosion resistance, and the use of electrode current collectors for the preparation of electrode current collectors can effectively reduce corrosion caused by liquids and prolong the service life of liquid metal batteries.

(3) The preparation method of the negative electrode current collector structure of the present invention is simple and easy to operate, can be produced by a standardized process, has controllable processing accuracy, can greatly improve the consistency of the final product, and has high production efficiency, reduces costs, and is suitable for mass production.

Description of drawings

1 is a schematic structural diagram of a double-layer negative electrode current collector for a liquid metal battery of the present invention;

Figure 2 is a schematic view of the structure of the electrode rod of the present invention;

Fig. 3 is the nut structure schematic diagram of the present invention;

4 is a schematic structural diagram of a foamed alloy impregnated with lithium of the present invention;

FIG. 5 is a schematic structural diagram of the foam alloy without immersion in lithium of the present invention;

FIG. 6 is a schematic diagram of the charge-discharge curve of the battery assembled with the double-layer negative electrode current collector of the present invention.

Throughout the drawings, the same reference numbers are used to refer to the same elements or structures, wherein:

1- Electrode rod, 2- Nut, 3- Foam alloy A, 4- Foam alloy B.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not 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.

1 is a schematic structural diagram of a double-layer negative electrode current collector for a liquid metal battery of the present invention, as shown in FIG. 1 , which includes an electrode rod, a foamed alloy A impregnated with lithium, and a foamed alloy B not impregnated with lithium,

Wherein, the foam alloy A and foam alloy B are arranged coaxially, with threaded through holes in the middle, the inner diameter of the threaded through holes of the foam alloy A and the threaded through holes of the foam alloy B are the same, and the foam alloy B There is also a groove coaxially arranged with the threaded through hole at the bottom, the groove is used to install the nut, the shape of the groove matches the shape of the above-mentioned nut, and the inner diameter of the groove is larger than the inner diameter of the threaded through hole, The foamed alloy A and the foamed alloy B are coaxially sleeved on the bottom of the electrode rod from top to bottom, and the foamed alloy A and foam The alloy B is fixed on the bottom of the electrode rod, and the nut, the foamed alloy A and the foamed alloy B are in close contact.

In a preferred embodiment of the present invention, the lithium-impregnated foam alloy A is formed by soaking the foam alloy in high-temperature molten lithium until the absorption is saturated, and then cooling.

In another preferred embodiment of the present invention, both the foamed alloy A and the foamed alloy B are prepared from iron-nickel foamed alloy, iron foamed alloy, nickel foamed alloy, cobalt-nickel foamed alloy or nickel-chromium foamed alloy. All made of stainless steel.

In another preferred embodiment of the present invention, the lower end of the electrode rod is provided with a thread, and the thread is used for matching with the nut and the threaded through holes on the foam alloy A and the foam alloy B.

In another preferred embodiment of the present invention, the bottom of the nut at the bottom of the foam alloy B is flush with the bottom end of the electrode rod.

In order to achieve the above object, according to one aspect of the present invention, there is provided a method for preparing a double-layer negative electrode current collector for a liquid metal battery as described above, which is characterized by comprising the following steps:

S1. Prepare a mold to prepare a foamed alloy with the same shape as the foamed alloy A, and a foamed alloy B with the same shape as the foamed alloy A and a groove at the bottom for use;

S2. Put the foamed alloy with the same shape as the foamed alloy A obtained in step S1 into high-temperature molten lithium and soak it until the foamed alloy is absorbed to a saturated state, and then take out and cool to obtain the foamed alloy A soaked with lithium;

S3. Put the bottom nut, foam alloy B, foam alloy A and the nut on the upper part of foam alloy A on the electrode rod in sequence from bottom to top, and rotate and tighten them one by one from bottom to top until the contact surfaces between them are in close contact. Double layer anode current collector.

In a preferred embodiment of the present invention, the nut on the bottom after tightening in step S3 is located in the groove at the bottom of the foam alloy B, and the lower surface of the nut in the bottom groove and the lower surface of the electrode rod are at the same level.

In order to better explain the present invention, a specific embodiment is given below:

first part:

As shown in Fig. 2-5, the double-layer negative electrode current collector for liquid metal battery provided by the present invention is processed as shown in the figure. First, the electrode rod in Fig. 2 is used as the shaft, the nut in Fig. 3, and the foam filled with lithium in Fig. 4. Alloy A, Fig. 5. The foamed alloy B that has not been immersed in lithium is assembled on the electrode rod of Fig. 2 from top to bottom, and all components are screwed to the upper part of the electrode rod of Fig. 2 as much as possible; Screw the nut to the lowermost end of the electrode rod in Figure 2, and the lower surface is at the same level as the lower surface of the electrode rod in Figure 2. The third step is to drag the foam alloy that is not immersed in lithium in Figure 5 down until it fully fits with the bottom nut; rotate the foam alloy A that is full of lithium in Figure 4 down to the same level as the foam that is not immersed in lithium in Figure 5. The upper surface of the alloy is in close contact; the upper nut of Fig. 3 is rotated downward to be in contact with the upper surface of the foam alloy A impregnated with lithium in Fig. 4.

Using the double-layer negative electrode current collector for liquid metal battery of the present invention, and adopting foam alloy to adsorb liquid lithium, on the one hand, the effective binding of liquid lithium is realized, and on the other hand, the contact area between lithium and the negative electrode current collector is increased, thereby improving the The reaction rate of the negative electrode material is improved; the nut fixing method is adopted to effectively realize the connection between the iron-nickel foam alloy and the negative electrode current collector rod, and at the same time, it can be completely completed with standardized components, which greatly reduces the error caused by manual fixing; the most important thing , The design of the double-layer iron-nickel foam alloy can effectively control the adsorption amount of lithium in the negative electrode, and avoid the stress damage caused by lithium rejection to the iron-nickel foam alloy.

the second part:

Using the double-layer negative electrode current collector and the preparation method of the present invention, a liquid metal battery capable of stable charge and discharge is prepared. As shown in Figure 6, the upper layer curve is the voltage-time curve, and the lower layer curve is the current-time curve. The results of multiple experiments prove that the performance of the batteries prepared by using the above-mentioned double-layer negative current collectors has a high consistency.

the third part:

The cycle performance test of the battery prepared by using the above-mentioned double-layer negative current collector:

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims (7)

1. a kind of double-deck negative current collector for liquid metal cell, which is characterized in that it includes electrode stem (1), is saturated with lithium Foamed alloy A (3) and not dipped lithium foamed alloy B (4),

Wherein, the foamed alloy A (3) and the foamed alloy B (4) coaxial arrangement, and centre is provided with tapped through hole, institute The tapped through hole for stating foamed alloy A (3) is identical with the internal diameter of the tapped through hole of the foamed alloy B (4), the foamed alloy B (4) bottom is there are also the groove with tapped through hole coaxial arrangement, and the groove is for installing nut, the shape of the groove and above-mentioned spiral shell Female shape matches, and the internal diameter of the groove is greater than the internal diameter of the tapped through hole；The foamed alloy A (3) and foam Alloy B (4) is sequentially coaxially set in the bottom of the electrode stem from top to bottom, by being arranged on foamed alloy A (3) top Nut and the foamed alloy B (4) bottom groove in nut, this foamed alloy A (3) and this foamed alloy B (4) is fixed In the bottom of the electrode stem, fitted closely between the nut, foamed alloy A and foamed alloy B.

2. bilayer negative current collector as described in claim 1, which is characterized in that the foamed alloy A (3) is by foamed alloy It is dipped into high-temperature fusion lithium until absorbing saturation, then cooling forms.

3. bilayer negative current collector as claimed in claim 1 or 2, which is characterized in that the foamed alloy A (3) and foam close Golden B (4) is all made of iron nickel foam alloy, iron foamed alloy, nickel foam alloy, cobalt nickel foam alloy or nickel chromium triangle foamed alloy material Preparation, the nut are all made of stainless steel preparation.

4. bilayer negative current collector as claimed in claim 3, which is characterized in that the lower end of the electrode stem (1) is provided with spiral shell Line, the screw thread are used to match with the tapped through hole on the nut and the foamed alloy A (3) and the foamed alloy B (4) It closes.

5. bilayer negative current collector as claimed in claim 4, which is characterized in that the nut bottom of foamed alloy B (4) bottom Portion is concordant with the electrode stem (1) bottom end.

6. the preparation method for the double-deck negative current collector of liquid metal cell, feature exist as claimed in claim 1 or 2 In, comprising the following steps:

S1. prepare mold, prepare foamed alloy identical with foamed alloy A shape, and the identical and bottom with foamed alloy A shape The reeded foamed alloy B (4) in portion is stand-by；

S2. foamed alloy identical with foamed alloy A shape obtained in step S1 is put into high-temperature fusion lithium and is impregnated, until The foamed alloy is absorbed into saturation state, and the foamed alloy A (3) for being saturated with lithium is made after taking out cooling；

S3. from bottom to up by the nut of bottom, foamed alloy B (4), foamed alloy A (3) and the nut on foamed alloy A (3) top It is sequentially sleeved on electrode stem (1), rotation is screwed to mutual contact surface and fits closely one by one from bottom to up, is made double-deck negative Pole collector.

7. preparation method as claimed in claim 6, which is characterized in that the nut for tightening rear bottom in step S3 is located at foam conjunction In the groove of golden B (4) bottom, and the lower surface of bottom groove inner nut and electrode stem (1) lower surface are in same level.