CN113991067B - Open lithium metal negative electrode secondary battery - Google Patents

Abstract

The application relates to an open type lithium metal negative electrode secondary battery, which comprises a sealed battery shell filled with electrolyte, wherein three rolls are arranged in the sealed battery shell, the first roll is a working roll, the second roll is a positive electrode roll, the third roll is a lithium metal negative electrode roll, the three rolls are driven by one or more motors, a positive electrode belt, a lithium metal negative electrode belt and a diaphragm are wound on the working roll, the positive electrode belt, the lithium metal negative electrode belt and the diaphragm are discharged when the working roll is unreeled to rotate, and meanwhile, the positive electrode roll and the negative electrode roll are wound to rotate and are wound in the positive electrode belt and the lithium metal negative electrode belt; dendrite flattening equipment is arranged between the working roll and the lithium metal negative electrode roll, and dendrite on the surface of the lithium metal negative electrode belt is flattened through the dendrite flattening equipment when the lithium metal negative electrode belt is released and retracted to move. The battery can effectively eliminate dendrites of the lithium metal cathode.

Description

An open lithium metal negative electrode secondary battery

Technical field

The invention belongs to the technical field of lithium ion batteries, and specifically relates to an open lithium metal negative electrode secondary battery.

Background technique

Lithium metal anode secondary batteries have very high mass specific energy and have attracted research investment from many experts for more than ten years. However, the dendrite problem of lithium metal anode has not been effectively solved.

Dendrites grow during charging based on the deposition of lithium atoms. Research believes that dendrites are produced for two reasons: First, when the lithium metal anode belt is processed and produced, its surface layer cannot be ideally flat at the atomic level, which will inevitably produce the result that some atoms are high and some are low. . Electrons have peak-gathering characteristics and will first gather at high points. Therefore, many electrons are first gathered at the high point, which immediately attracts lithium ions to deposit, forming dendrites. The second reason is that the lithium ions coming from the positive electrode can only reach the surface of the lithium metal anode from the channels in the separator. However, these channels are unevenly distributed on the surface of the lithium metal anode. Wherever they come into contact with the channels, there is definitely a probability of lithium ion deposition. are all very high, so dendrites will inevitably form. When the original high points on the lithium metal belt happen to hit the channels on the diaphragm, these two reasons will definitely accelerate the growth of dendrites. Some experts believe that the force generated by the growth of dendrites pierced the membrane, but we do not think so. Our idea is that dendrites grow along the lithium ion channel in the separator and encounter the positive electrode, causing a short circuit. If the lithium ion channel of the separator is curved, then the dendrite growth is also curved. On the contrary, if the lithium ion channel of the separator is straight, then the growth of dendrites will also be straight. So as long as there is a separator, as long as there are lithium ion channels on the separator, dendrites will inevitably be produced.

How to eliminate the problem of dendrites. Currently, the methods of domestic and foreign experts are divided into three aspects: one is to physically dope and modify the surface of lithium metal, such as using an alloy of lithium and aluminum to suppress the generation of dendrites; the other is to change the electrolysis The formula of the liquid dissolves the dendrites through the electrolyte; the third is to use a solid electrolyte and use physical force to prevent the dendrites from penetrating the separator. However, in the past ten years, various studies have not yielded results, dendrites still exist, and short circuits still occur. Some experts believe that during discharge, the positively charged ions in the dendrites move toward the positive electrode, and the electrons move toward the negative electrode, and the dendrites will disappear, leaving only the interface material on the surface of the dendrites. When the number of dendrites increases and continues to occur, interface materials will accumulate and affect the conduction of lithium ions. Only by eliminating the generation of dendrites will this phenomenon not occur, because the interface layer will not grow on the original interface layer, but will only grow on the surface of new dendrites.

By analyzing the current research status, it can be seen that doping other metals on the surface of lithium metal can reduce the generation of dendrites, but this will affect the conduction of lithium ions. The composition of the electrolyte is a delicate combination. Adding dissolved matter to dissolve the dendrites will seriously affect the conduction of ions, and the dissolved lithium remaining in the electrolyte will also cause electronic short circuit conduction. The electrolyte uses a solid electrolyte with a certain hardness, hoping to block the generation of dendrites. However, any solid electrolyte must have ion channels, and dendrites grow along the channels, so the hardness of the electrolyte has nothing to do with blocking dendrite puncture. . From the analysis of the above three types of methods, we must decisively abandon the old thinking and find another way. Open the battery that has been closed for decades and release the lithium metal negative electrode strip for repair at any time, creating a new type of open and repairable battery. The latest and most effective direction is to use mechanical methods to eliminate dendrites with mechanical properties.

Contents of the invention

The object of the present invention is to provide an open lithium metal negative electrode secondary battery that can effectively eliminate dendrites in the lithium metal negative electrode.

In order to achieve the above object, the technical solution adopted by the present invention is: an open lithium metal negative electrode secondary battery, including a sealed battery case filled with electrolyte, and three kinds of rolls are provided in the sealed battery case. The first kind of roll It is a working roll, the second roll is a positive electrode roll, and the third roll is a lithium metal negative electrode roll. The three rolls are driven by one or more motors. The working roll is wound with a positive electrode tape, a lithium metal negative electrode tape, and a separator. , when the working roll is unwinding and rotating, the positive electrode belt, lithium metal negative electrode belt and separator are released. At the same time, the positive electrode roll and the negative electrode roll are rewinding and rotating, and the positive electrode belt and lithium metal negative electrode belt are taken in; between the working roll and the lithium metal negative electrode roll A dendrite flattening device is provided. When the lithium metal negative electrode belt is released and retracted, the dendrites on the surface of the lithium metal negative electrode belt are flattened by the dendrite flattening device.

Further, the dendrite flattening equipment is a roller equipment. The roller equipment includes upper rollers and lower rollers respectively located on the lower side of the lithium metal negative electrode belt. The lithium metal negative electrode belt is rolled from the upper and lower sides. When the roller passes through the middle, the roller generates pressure on the surface of the lithium metal negative electrode belt, thereby flattening the dendrites on the surface of the lithium metal negative electrode belt.

Further, the dendrite flattening equipment is a vibration equipment. The vibration equipment includes a vibrating plate and a fixed plate respectively located on the lower side of the lithium metal negative electrode belt. The lithium metal negative electrode belt passes between the vibrating plate and the fixed plate. At this time, the impact force and reaction force of the flat plate flatten the dendrites on both surfaces of the lithium metal negative electrode.

Further, during the production of the lithium metal negative electrode belt, both surfaces are smoothed; the thickness of the lithium metal negative electrode belt is increased, so that one lithium metal negative electrode belt and multiple positive electrode belts can be rotated to form a battery that can be charged and discharged roll.

Furthermore, the lithium-ion battery uses a large-pore diaphragm with a diameter greater than 100um; when manufacturing the positive electrode belt, graphene fragments are used instead of carbon particles to add to the positive electrode active material to increase the bending resistance of the positive electrode belt.

Further, the charger used with the lithium-ion battery is equipped with a charging counter or a battery capacity detector; when the charging time reaches the set value or the charging capacity reaches the set value, the charger issues an instruction to stop charging, and The next charge is limited to starting the lithium metal negative electrode belt flattening system to perform dendrite flattening operation, and then charging.

Further, position sensing elements are provided at both ends of the lithium metal negative electrode belt. The pole tabs on the lithium metal negative electrode tape and the pole tabs on the positive electrode tape in the working roll are electrically connected to the outside through the pole tabs and the electrical connecting piece. The elastic contact is realized.

Further, a rotation counter is provided on the reels of the three types of rolls to issue instructions when necessary to stop the unwinding and rewinding rotation of the three types of rolls in the battery.

Further, the separators are attached to both sides of the positive electrode belt, and perform unwinding and rewinding movements together with the positive electrode belt.

Further, the working roll, positive electrode roll, lithium metal negative electrode roll and drive motor are all sealed in the battery case, and the sealed space is filled with electrolyte or inert gas.

Furthermore, when the lithium-ion battery is used in high-power batteries, multiple rolls of the same type can be arranged on the reels of the three rolls to increase capacity.

Compared with the existing technology, the present invention has the following beneficial effects: it provides an open lithium metal negative electrode secondary battery, which changes a closed battery into an open and repairable battery, and uses mechanical flattening equipment to eliminate mechanical properties. dendrites, more effective than all chemical elimination methods. To solve the problem of dendrites, the battery can make the lithium metal belt thicker and allow multiple positive electrode belts to alternately work with one lithium metal belt. This can exponentially increase the specific energy of the battery and make its endurance performance equal to that of gasoline fuel. The open lithium anode secondary battery can be used in various scenarios such as high-power energy storage batteries.

Description of the drawings

Figure 1 is a schematic structural diagram of an open lithium metal negative electrode secondary battery according to an embodiment of the present invention.

Figure 2 is a schematic diagram of roller equipment flattening dendrites in an embodiment of the present invention.

Figure 3 is a schematic diagram of the vibration equipment flattening dendrites in the embodiment of the present invention.

Figure 4 is a schematic structural diagram of an open lithium metal negative electrode secondary battery with multiple positive electrodes in an embodiment of the present invention.

Figure 5 is a schematic diagram of the conduction of the tab in the embodiment of the present invention.

In the picture: 1—battery casing; 2—working roll; 3—dendrite flattening equipment; 4—lithium metal negative electrode strip; 5—lithium metal negative electrode roll; 6—positive electrode roll; 7—upper roller; 8—lower Roller; 9—vibrating plate; 10—fixed plate; 11—positive electrode external electrical connecting piece; 12—positive electrode tab; 13—lithium negative electrode tab; 14—negative electrode external electrical connecting piece; 15—reel; 16—positive electrode belt.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and examples.

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meanings commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular forms are also intended to include the plural forms unless the context clearly indicates otherwise. Furthermore, it will be understood that when the terms "comprises" and/or "includes" are used in this specification, they indicate There are features, steps, operations, means, components and/or combinations thereof.

As shown in Figure 1, this embodiment provides an open lithium metal negative electrode secondary battery, including a sealed battery case filled with electrolyte. Three types of rolls are provided in the sealed battery case 1. The first type of roll It is the working roll 2, the second roll is the positive electrode roll 6, the third roll is the lithium metal negative electrode roll 5, where the working roll is a battery roll that can be charged and discharged, the three rolls are driven by one or more motors, the working roll 2 is wound with the positive electrode belt 16, the lithium metal negative electrode belt 4 and the separator. When the working roll 2 is unwinding and rotating, the positive electrode belt, the lithium metal negative electrode belt 4 and the separator are released. At the same time, the positive electrode roll 6 and the negative electrode roll 5 are rewinding and rotating. Enter the positive electrode belt and the lithium metal negative electrode belt 4; a dendrite flattening device 3 is provided between the working roll 2 and the lithium metal negative electrode roll 6. When the lithium metal negative electrode belt 4 is released and retracted, through the dendrite pressing The flattening device 3 flattens the dendrites on the surface of the lithium metal negative electrode belt.

In this embodiment, the dendrite flattening equipment may be a roller equipment. The roller equipment includes an upper roller 7 and a lower roller 8 respectively located on the lower side of the lithium metal negative electrode belt. The lithium metal When the negative electrode belt passes between the upper and lower rollers, the rollers generate pressure on the surface of the lithium metal negative electrode belt, thus flattening the dendrites on the surface of the lithium metal negative electrode belt. The dendrite flattening equipment can also be a vibration equipment. The vibration equipment includes a vibrating plate 9 and a fixed plate 10 respectively located on the lower side of the lithium metal negative electrode belt. The lithium metal negative electrode belt is moved from the middle of the vibrating plate and the fixed plate. When passing by, the impact force and reaction force of the flat plate flatten the dendrites on both surfaces of the lithium metal negative electrode.

In this embodiment, the unwinding and rewinding of the lithium metal strip are driven by a micro motor in the battery case. The power for flattening the dendrites and the power for the motor are both supplied by external power during charging. Because the hardness of lithium metal is very low, the power required to flatten the newly produced dendrites is very small, so its motor and flattening equipment are very small. The dendrite flattening equipment of a 10Ah battery only has half a unit. Pencil size. In addition to mechanical methods, there are other methods to eliminate dendrites: During the manufacturing process of the lithium metal negative electrode belt, its two surfaces are flattened and a separator with the largest pore size is used. For example, the lithium metal belt is repeatedly passed between the upper and lower rollers, and the smooth mirror-like upper and lower rollers are pressed against the upper and lower planes of the lithium metal belt while rotating. You can also choose a suitable fiber wheel to polish both surfaces of the lithium metal belt. The lithium-ion battery uses a large-pore diaphragm with a diameter greater than 100um.

In this embodiment, the charger used with the lithium-ion battery is provided with a charging counter or a battery capacity detector. When the charging time reaches the set value or the charging capacity reaches the set value, the charger issues a command to stop charging, and restricts the next charge to start the lithium metal negative electrode belt flattening system to perform dendrite flattening operation, and then proceed. Charge. When the charger's detection instrument determines that the dendrites on the surface of the lithium metal strip need to be flattened, the flattening equipment will automatically flatten the dendrites after the charging plug is plugged in. Therefore, the battery of the present invention will not have the difficulty of dendrites penetrating the separator. The above specified value refers to the state where the dendrites have just grown into the separator holes after several charges. This is the best state for flattening the dendrites. In other words, users do not need to worry about when to flatten the lithium metal strip. Users only need to plug in the charger during use, and this product can automatically solve the above problems. Even if the present invention does not use flattening equipment, it can significantly increase the number of cycles of the lithium negative electrode secondary battery by simply smoothing the surface of the lithium metal strip and using a large-pore diaphragm. When the present invention adds mechanical flattening equipment, it can achieve the purpose of long-term circulation.

Lithium metal belts have very little resistance to lithium ions. Therefore, when manufacturing lithium metal negative electrode belts, their thickness can be thickened, so that one lithium metal belt can be rotated with multiple positive electrode belts to form a battery roll that can be charged and discharged. As shown in Figure 4. When the positive electrode strip in the working roll is fully charged, the working roll will rotate to release the positive electrode strip, and at the same time, the first positive electrode roll will retract the positive electrode strip. Next, the second positive electrode roll will release the positive electrode strip and the lithium metal strip and put it into the working roll to continue charging. When the reorganized working roll is fully charged, the working roll will rotate and release the second positive electrode strip, and at the same time, the second positive electrode roll will retract into this positive electrode strip. Finally, repeat the above process to continue charging the third positive electrode roll. This is how open lithium negative multi-positive secondary batteries work. During discharge, the multiple positive electrode coils also rotate in this way. This multi-positive electrode rotation method can increase the mass specific energy of the lithium metal battery of the present invention several times, making the cruising range equal to or exceeding the gasoline fuel level.

In this embodiment, position sensing elements such as magnetic objects are provided at both ends of the lithium metal negative electrode belt, which can issue instructions when necessary to stop the unwinding and rewinding rotation of the three types of rolls in the battery of the present invention.

In this embodiment, a rotation counter is provided on the reels of the three types of rolls to issue instructions when necessary to stop the unwinding and rewinding rotations of the three types of rolls in the battery.

In this embodiment, the separators are attached to both sides of the positive electrode belt, and perform unwinding and rewinding movements together with the positive electrode belt. This can protect the active material of the positive electrode from being damaged and keep the active material in a moist state with the electrolyte.

In this embodiment, the working roll, positive electrode roll, lithium metal negative electrode roll and drive motor are all sealed in the battery case, and the sealed space is filled with electrolyte or inert gas.

In this embodiment, when manufacturing the cathode belt, graphene fragments are used instead of carbon particles and added to the cathode active material to increase the bending resistance of the cathode belt.

In this embodiment, the external electrical connection between the tabs on the lithium metal negative electrode band and the tabs on the positive electrode band in the working roll is realized through the elastic contact between the tabs and the electrical connecting piece. The electrical connection piece includes a positive external electrical connection piece and a negative external electrical connection piece, as shown in Figure 5. Elastic contact conduction is a commonly used principle in electrical equipment, and it works safely and reliably.

When the present invention is applied to high-power batteries, multiple rolls of the same type can be arranged on the reels of three types of rolls to increase capacity.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any skilled person familiar with the art may make changes or modifications to equivalent changes using the technical contents disclosed above. Example. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims (9)

1. An open lithium metal negative electrode secondary battery, including a sealed battery case filled with electrolyte, characterized in that three types of rolls are provided in the sealed battery case, the first roll is a working roll, and the second roll is a working roll. The roll is a positive electrode roll, and the third roll is a lithium metal negative electrode roll. The three rolls are driven by one or more motors. The working roll is wound with a positive electrode strip, a lithium metal negative electrode strip and a separator. When the working roll is unrolled and rotated, The positive electrode belt, the lithium metal negative electrode belt and the separator are released, and at the same time, the positive electrode roll and the lithium metal negative electrode roll are rolled up and rotated to retract the positive electrode belt and the lithium metal negative electrode belt; there is a dendrite pressure between the working roll and the lithium metal negative electrode roll. When the lithium metal negative electrode belt is released and retracted, the dendrites on the surface of the lithium metal negative electrode belt are flattened by the dendrite flattening device; When the lithium metal negative electrode belt is manufactured, its two surfaces are smoothed; the thickness of the lithium metal negative electrode belt is increased, and one lithium metal negative electrode belt and multiple positive electrode belts are rotated to form a battery roll that can be charged and discharged; When the positive electrode strip in the working roll is fully charged, the working roll rotates to release the positive electrode strip, and at the same time, the first positive electrode roll is retracted into the positive electrode strip; then the second positive electrode roll is released and the positive electrode strip is retracted together with the lithium metal negative electrode strip. Enter the working roll and continue charging; when the reorganized working roll is fully charged, the working roll rotates to release the second positive electrode strip, and at the same time the second positive electrode roll is retracted into this positive electrode strip; finally, repeat the above process to continue. Charging of the third positive coil. 2. An open lithium metal negative electrode secondary battery according to claim 1, characterized in that the dendrite flattening equipment is a roller equipment, and the roller equipment includes: There are upper rollers and lower rollers on the lower side. When the lithium metal negative electrode belt passes between the upper and lower rollers, the rollers generate pressure on the surface of the lithium metal negative electrode belt, thereby flattening the dendrites on the surface of the lithium metal negative electrode belt. 3. An open lithium metal negative electrode secondary battery according to claim 1, characterized in that the dendrite flattening device is a vibration device, and the vibration device includes a lithium metal negative electrode belt and a lower side. There are vibrating flat plates and fixed flat plates. When the lithium metal negative electrode belt passes between the vibrating flat plate and the fixed flat plate, the impact force and reaction force of the flat plate flatten the dendrites on both surfaces of the lithium metal negative electrode belt. 4. An open lithium metal negative electrode secondary battery according to claim 1, characterized in that the open lithium metal negative electrode secondary battery adopts a large-pore diaphragm with a diameter greater than 100um; when manufacturing the positive electrode belt, Graphene fragments are added to the cathode active material instead of carbon particles to increase the bending resistance of the cathode belt. 5. An open lithium metal negative electrode secondary battery according to claim 1, characterized in that the charger used with the open lithium metal negative electrode secondary battery is provided with a charge counter or a battery capacity detector. ; When the charging time reaches the set value or the charging capacity reaches the set value, the charger issues a command to stop charging, and restricts the next charging to start the lithium metal negative electrode belt flattening system to perform dendrite flattening operation, and then to charge. 6. An open lithium metal negative electrode secondary battery according to claim 1, characterized in that position sensing elements are provided at both ends of the lithium metal negative electrode belt, and the electrodes on the lithium metal negative electrode belt in the working roll are The external electrical connection between the tabs and the tabs on the positive electrode band is achieved through the elastic contact between the tabs and the electrical connecting piece. 7. An open-type lithium metal negative electrode secondary battery according to claim 1, characterized in that a rotation counter is provided on the reels of the three types of rolls to issue instructions when necessary to stop the three types of batteries. Unwinding and rewinding rotation of the roll. 8. An open lithium metal negative electrode secondary battery according to claim 1, characterized in that the separator is attached to both sides of the positive electrode belt and performs unwinding and rewinding movements together with the positive electrode belt. 9. An open lithium metal negative electrode secondary battery according to claim 1, characterized in that the working roll, the positive electrode roll, the lithium metal negative electrode roll and the driving motor are all sealed in the battery casing. The space is filled with electrolyte or inert gas.