TWI664253B - Flexible battery - Google Patents

Abstract

The invention relates to a flexible battery, which includes a first active material layer, an intermediate layer, a second active material layer, a first interface between the first active material layer and the intermediate layer, or a second interface between the second active material layer and the intermediate layer. Any one of the second interfaces includes a first adhesive, and the first adhesive includes at least a first linear polymer and a first crystallization inhibitor, so that the active material layer, the intermediate layer, or the interface has sufficient energy. The adhesiveness and softness of the battery make it difficult for the electrochemical reaction objects to collapse or separate after the battery is bent, and improve the ion conductivity and electronic conductivity of the battery.

Description

Flexible battery

The present invention relates to a flexible battery, and particularly to a flexible battery that can prevent the internal components of an electrochemical reaction object from being bent or broken due to bending.

Recently, various electronic devices have been developed accordingly. In order to make this electronic device more in line with the trend of lightness and thinness, the space allocation within the electronic device has become an important issue, and a flexible battery that can be installed in a non-planar surface has brought a solution to this problem. One of the strategies. However, in the process of bending, the electrode layer often collapses, resulting in a decrease in the ion conductivity and a decrease in battery efficiency.

As far as the characteristics of the battery are concerned, the material selection of the electrode layer, the electrolyte, and the isolation layer is an important point affecting the ion conductivity and the electron conductivity. The electrode layer system mainly includes an active material layer and a current collector layer. If the active material layer and the current collector layer have better adhesion, it can effectively shorten the moving distance of electrons and ions in the electrode layer, and at the same time, make the resistance inside the electrode layer The value is reduced, and the conversion efficiency of the electrochemical is improved. In more detail, when the active material layer and the current collector layer are tightly bonded, the distance of electron and ion migration is shortened, and the interface barrier between the layers is reduced, which further improves the Coulomb efficiency. After the battery is repeatedly charged and discharged, It can still maintain its capacitance. In addition, in the selection of the adhesive in the active material layer, in addition to significantly affecting the adhesion state between the various layer structures, the content and distribution of the active material in the active material layer can be directly determined. With the connection of the active material and the adhesive, The better the relationship, the more ideal the active material content and arrangement in the active material layer, and of course the battery capacity can be increased. In addition, the adhesive in the isolation layer can not only provide the adhesion between the isolation layer and the active material layer, but also in the specific isolation layer structure, such as a ceramic isolation layer, the choice of the adhesive further affects the content of the ceramic material in the ceramic isolation layer. , The ability of electrolyte adsorption, the ability of electrical isolation ... and other characteristics of the isolation layer.

According to the foregoing point of view, at present, the general lithium battery is commonly used Polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-trichloroethylene (PVDF-HFP), styrene-butadiene rubber (styrene-butadiene (SBR)) and other flexible adhesives, these adhesives The structure is a linear structure, so it can provide a very good adhesion effect in the XY axis. However, after the adhesive is heat-treated or pressed, its polymer chain will be affected by thermal energy and pressure. A crystallization reaction occurs, in other words, a large amount of crystals are generated at the interface between the active material layer and the isolation layer to which the above-mentioned adhesive is added. After the battery is bent, due to the structure of the adhesive itself, Or the crystalline structure is damaged by external forces, which will reduce the adhesion to the active material, which will cause cracks in the electrode layer or the isolation layer, and even the separation of the active material layer from the collector layer and the isolation layer, which will eventually lead to ion and electron conduction. The degree of degradation decreases, causing a problem that the battery charge and discharge efficiency becomes poor. On the other hand, if all adhesives such as epoxy, acrylic acid, and polyacrylonitrile (PAN) are used, even if the adhesive effect is better, the rigidity is too high and the flexibility is insufficient. It is difficult to meet the requirements of battery bending.

In view of the foregoing, the present invention proposes a flexible battery in order to effectively overcome the problems mentioned above in view of the lack of the conventional technology.

The main object of the present invention is to provide a flexible battery, which can avoid the situation that the flexible battery collapses or separates due to the fracture along the crystal grain boundary after bending, and the ion conductivity and the electron conductivity caused by it Poor question.

To achieve the above object, the present invention proposes a flexible battery including a first substrate, a second substrate, and a plastic frame. The plastic frame is sandwiched between the first substrate and the second substrate in an orthographic projection direction. Therefore, the first The substrate, the second substrate, and the rubber frame enclose an enclosed space for containing an electrochemical reaction object. The electrochemical reaction object includes a first active material layer, a second active material layer, and an intermediate layer, and the first active material A layer is disposed adjacent to and electrically connected to the first substrate, a second active material layer is disposed adjacent to and electrically connected to the second substrate, and an intermediate layer is sandwiched between the first active material layer and the second active material layer, and The middle layer system provides the function of electrical insulation. The first active material layer and the second active material layer on both sides of the interlayer, a first interface is located at the junction of the first active material layer and the intermediate layer, and a second interface is located at the junction of the second active material layer and the intermediate layer. The invention is characterized in that any one of the first active material layer, the second active material layer, the intermediate layer, the first interface or the second interface includes a first adhesive, and the first adhesive includes a first linear polymer and a first crystal. Inhibitor, and the weight percentage of the first crystallization inhibitor to the first adhesive is between 0.05 wt.% And 70 wt.%.

Detailed descriptions will be provided below through specific embodiments to make it easier to understand the purpose, technical content, features and effects of the present invention.

1‧‧‧ flexible battery

22‧‧‧first substrate

22’‧‧‧second substrate

24‧‧‧ plastic frame

30‧‧‧ Electrochemical reaction object

302‧‧‧first active material layer

302’‧‧‧second active material layer

304‧‧‧ middle layer

a‧‧‧first interface

b‧‧‧Second interface

LP‧‧‧Ladder Polymer

FIG. 1 is a schematic structural diagram of an embodiment of a flexible battery according to the present invention.

Figures 2A and 2B are partial structural diagrams of the flexible battery of the present invention when it is bent and restored.

Please refer to Figure 1 first. The flexible battery 1 includes a first substrate 22, a second substrate 22 ', and a plastic frame 24. The plastic frame 24 is sandwiched between the first substrate 22 and the second substrate 22' in an orthographic projection direction. The two substrates and the rubber frame are enclosed to form an enclosed space, and the enclosed space contains an electrochemical reaction object 30. The electrochemical reaction object 30 includes a first active material layer 302, a second active material layer 302 ', and an intermediate layer 304. The first active material layer 302 is disposed adjacent to the first substrate 22, the second active material layer 302 'is disposed adjacent to the second substrate 22', and the intermediate layer 304 is sandwiched between the first active material layer 302 and the second active material Between layers 302 '. The intermediate layer 304 provides a function of electrical insulation to electrically block the first active material layer 302 and the second active material layer 302 'located on both sides of the intermediate layer 304. There is an interface at the junction of the first active material layer 302, the intermediate layer 304, and the second active material layer 302 '. For example, there is a first interface a at the junction of the first active material layer 302 and the intermediate layer 304. There is a second interface b at the junction between the intermediate layer 304 and the second active material layer 302 '.

In the present invention, a first adhesive is added to the first active material layer 302, the intermediate layer 304, the second active material layer 302 ', the first interface a or the second interface b. The first adhesive is composed of a first linear polymer and a first crystallization inhibitor. And the weight percentage of the first crystallization inhibitor to the first adhesive is between 0.05 wt.% And 70 wt.%.

The above-mentioned first crystallization inhibitor can be any additive which can prevent the linear polymer from generating a lattice arrangement, for example, a dopant having a side chain polymer, a bridging polymer, a nanometer powder, etc., so that In addition to providing good adhesion, the first adhesive can also make the main component in the first adhesive, that is, the first linear polymer, maintain softness, thereby improving the bending resistance of the electrochemical reaction object. In this way, the overall resistance to bending or the flexibility limit of the battery can also be greatly improved.

The first linear polymer may be composed of a linear polymer having a certain degree of flexibility, and the linear polymer is selected from the group consisting of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-trichloro Ethylene (PVDF-HFP), Polytetrafluoroethene (PTFE), Acrylic Acid Glue, Epoxy, Polyethylene Oxide (PEO), Polyacrylonitrile (PAN) , Sodium carboxymethyl cellulose (CMMC), styrene-butadiene rubber (styrene-butadiene (SBR), polymethylacrylate, polyacrylamide, polyvinylpyrrolidone (PVP) ) And the above combination.

In the following, the cross-linking polymer is used as the first crystallization inhibitor as an example, but those skilled in the art know that the first crystallization inhibitor in this case can not only bridge the cross-linking polymer, so it is clear here.

When the first crystallization inhibitor is the first cross-linking polymer, the first cross-linking polymer is composed of a cross-linking polymer, and the cross-linking polymer is selected from epoxy resin and acrylic resin. (Acrylic Acid), polyacrylonitrile (PAN) and the combination of the above-mentioned network-type bridging polymer or polyimide (PI) and its ladder-like (ladder) bridging polymer (LP).

If there is no crystallization inhibitor, when the flexible battery 1 is heat-treated, the first linear polymer in the electrochemical reaction object will be heated due to its material characteristics. Crystallization, and if pressure treatment is applied at the same time, the phenomenon of crystallization will be more significant. Once the crystal size is too large or the degree of crystallization is too high, the crystals formed will become a three-dimensional obstacle in the structure, resulting in ions inside the flexible battery 1. The channel is blocked, greatly increasing the internal impedance of the battery. In addition, the crystal size is too large or the degree of crystallinity is too high. For example, the first active material layer 302, the second active material layer 302 ', or the layer of the intermediate layer 304, the first interface, and the second interface are located at positions where crystals are generated. , Both will easily break along the grain boundary when the flexible battery 1 is bent.

However, the present invention utilizes the characteristics of the first bridge polymer having good thermal stability and heat resistance. When the flexible battery 1 is heat-treated, the first bridge polymer can withstand high temperatures without melting, and is in contact with the first wire. Compared with high-molecular polymers, the first bridge polymer has more three-dimensional branched chains in its polymer structure, so the first bridge polymer can become the first linear under high temperature (or high temperature and high pressure) process conditions. The obstacle when the polymer forms crystals limits the size of the crystals formed by the first linear polymer and the degree of crystals to reduce the three-dimensional obstacles caused by the crystals, so that the ions can pass through more smoothly.

In addition, when any one of the first active material layer 302, the second active material layer 302 ', the intermediate layer 304, the first interface a or the second interface b includes a first adhesive, any of the remaining layers or interfaces One may further have a second adhesive, the second adhesive comprising at least a second linear polymer and at least a second crystallization inhibitor, the first adhesive being different from the second adhesive. The difference may be, for example, that the first linear polymer and the second linear polymer are the same, but the first crystallization inhibitor and the second crystallization inhibitor are different, or the first crystallization inhibitor and the second crystallization inhibitor are different The weight percentages of the agents in the adhesive are different. Of course, the first linear polymer and the second linear polymer may be different, but the first crystallization inhibitor is the same as the second crystallization inhibitor, and so on.

The types of optional components of the second linear polymer and the second crystallization inhibitor and the types of components of the first linear polymer and the first crystallization inhibitor used in the first adhesive may be the same, and details are not described herein again.

For example, the first active material layer 302 has a first adhesive, the intermediate layer 304 contains a second adhesive, and the second adhesive is composed of a second linear polymer and a second adhesive. The composition of the crystallization inhibitor, and the weight percentage of the second crystallization inhibitor in the second adhesive is not less than 50%. The first linear polymer and the second linear polymer described above may be the same or different, that is, the first linear polymer and the second linear polymer may be composed of the same linear polymer. Similarly, The first crystallization inhibitor and the second crystallization inhibitor may be the same or different.

Furthermore, having a side chain crystallization inhibitor will allow the adhesive to have better adhesion in the Z-axis direction. For example, when the first interface contains a first adhesive and the first crystallization inhibitor is a first bridging polymer, the first bridging polymer closely adheres the first active material layer 302 and the intermediate layer 304 in the Z-axis direction. , So that a good electronic continuity is maintained between the first active material layer 302 and the intermediate layer 304.

Furthermore, the first bridging polymer and / or the second bridging polymer can be ladder-shaped bridging polymers, such as polyimide (PI) and its derivatives. Compared with this type of bridging polymer, In terms of the aforementioned bridging polymers, the elasticity of the bridging polymers with a network structure is poor. Therefore, as shown in FIG. 2A and FIG. 2B, during the bending process of the electrochemical reaction object 30 under the external force, the ladder-shaped bridge polymer LP absorbs the stress during bending, so that the electrochemical reaction object 30 can be in the Z axis. Extending in the direction, it is not easy to crack, and after the external force received by the electrochemical reaction object 30 is removed, the ladder-shaped bridge polymer LP will return to the original state, thereby achieving repeated bending without damaging the electrochemical reaction object 30 the goal of.

The first substrate 22 and the second substrate 22 ′ described above may be a positive current collector plate or a negative current collector plate. For example, when the first substrate 22 is a positive current collector plate, the second substrate 22 ′ is a negative electrode. Current collector plate, and vice versa, the first active material layer 302 and the second active material layer 302 'can be a positive active material layer or a negative active material layer. For example, when the first active material layer 302 is a positive active material Layer, the second active material layer 302 'is a negative electrode active material layer, and vice versa.

In addition, the intermediate layer 304 is an isolation layer or an electrolyte layer in a battery, so it must have a certain degree of ionic conductivity and electronic insulation. At the same time, in order to respond to the flexible characteristics of the battery, it must also have flexibility. In addition to the second linear polymer, the second adhesive must also contain at least 50 wt.% Of the second bridging polymer, such as epoxy, acrylic acid, polyacrylonitrile, etc. (polyacrylonitrile; PAN) network-type bridging polymer, the bridging structure formed is a network, the overall structure is dense, and the second linear polymer with a linear structure will reduce the chance of the existence of large through-holes, and Improve electronic insulation. In addition, the PI of the ladder-shaped bridge structure can also be used. The ladder-shaped bridge structure can make the hole distribution state easy for ions to pass through. At the same time, the ladder-shaped bridge polymer LP has more electronic insulation properties. An appropriate ratio with the linear polymer forms a second adhesive to add the intermediate layer 304, so that the intermediate layer 304 achieves a better balance between ion conduction and electronic insulation.

Linear polymers can be used to improve adhesion on the XY plane. The first bridging polymer and the second bridging polymer are composed of bridging polymers. The bridging polymers can be used to improve the adhesion in the Z-axis direction and the ability of ion conduction, and at the same time interfere or reduce the heat treatment or lamination between the layers. The probability or degree of polymer crystals produced after processing. The adhesiveness referred to in the present invention refers to the ability of the layers (such as the substrate and the active material layer, the active material layer and the isolation layer) to adhere to each other, and the materials within the layer (such as the active material layer or the isolation layer) to each other. ability.

Further, the present invention adds a first adhesive to the first active material layer 302, the intermediate layer 304, the second active material layer 302 ', the first interface a or the second interface b, and further adds to the remaining layers. A second adhesive is added to any one, and by adjusting the ratio between the linear polymer and the bridging polymer in the first adhesive and / or the second adhesive, the active material layer and the intermediate layer in the electrochemical reaction object are adjusted. After heat treatment or compression treatment, it can still have softness, can withstand repeated bending, and avoid cracks along the grain boundary caused by the generation of crystalline particles.

At the same time, because the adhesive system with a crystallization inhibitor can make each layer have good adhesion and flexibility after heat treatment or compression treatment, the active material layer and the intermediate layer of the flexible battery of the present invention will not be easy when it is bent. The separation makes a better balance between the ion and electron continuity and the insulation, thereby improving the electrical capacity of the flexible battery.

All structures, materials, and processes disclosed in the present invention are applicable to various battery systems, for example, liquid batteries, gel batteries, solid batteries, liquid / gel batteries, liquid / solid batteries, or batteries. State / solid state mixing Integrated batteries, or so-called flexible lithium batteries, flexible lithium ion batteries, flexible lithium polymer batteries, flexible lithium metal batteries, flexible lithium ceramic batteries or flexible lithium metal ceramic batteries.

The above are merely preferred embodiments of the present invention, and are not intended to limit the scope of implementation of the present invention. Therefore, all equal changes or modifications made according to the features and spirit described in the scope of the application of the present invention shall be included in the scope of patent application of the present invention.

Claims (16)

A flexible battery includes: a first substrate; a second substrate; and a plastic frame, which is sandwiched between the first substrate and the second substrate in an orthogonal projection direction to form a surrounding space; And an electrochemical reaction object located in the enclosed space, the electrochemical reaction object includes: a first active material layer, which is disposed adjacent to the first substrate and is electrically connected thereto; a second active material layer, and The second substrate is disposed adjacent to and electrically connected to the second substrate; an intermediate layer is sandwiched between the first active material layer and the second active material layer, and electrically blocks the first active material layer from the second active material layer An active material layer; a first interface located at a joint surface of the first active material layer and the intermediate layer; and a second interface located at a joint surface of the second active material layer and the intermediate layer; Any of the first active material layer, the second active material layer, the intermediate layer, the first interface, or the second interface includes a first adhesive, and the first adhesive includes at least a first linear height. Molecules and at least one first crystallization inhibitor The first crystallization inhibitor may hinder the system generates a first linear polymer lattice arrangement, the first crystallization agents typically comprise the first agent, then the weight percentage-based range of 0.05wt.% ~ 70wt.%. The flexible battery according to claim 1, wherein the first crystallization inhibitor is selected from a polymer having a side chain, a first bridging polymer, or a nano-grade powder. The flexible battery according to claim 1, wherein the first substrate and the second substrate are a positive current collector plate and a negative current collector plate. The flexible battery according to claim 1, wherein the first active material layer is a positive active material layer, and the second active material layer is a negative active material layer. The flexible battery according to claim 1, wherein the intermediate layer is an isolation layer. The flexible battery according to claim 1, wherein the intermediate layer is an electrolyte layer. The flexible battery according to claim 1, wherein the first linear polymer is selected from the group consisting of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-trichloroethylene (PVDF-HFP), Polytetrafluoroethene (PTFE), Acrylic Acid Glue, Epoxy, Polyoxyethylene (PEO), Polyacrylonitrile (PAN), Sodium Carboxymethyl Cellulose (carboxymethyl cellulose (CMC)), linear polymers of styrene-butadiene rubber (styrene-butadiene (SBR), polymethylacrylate, polyacrylamide, polyvinylpyrrolidone (PVP) and the above Combination of linear polymers. The flexible battery according to claim 2, wherein the first bridge polymer is selected from the group consisting of epoxy, acrylic acid, polyacrylonitrile (PAN), and a combination thereof. Network-type bridging polymers. The flexible battery according to claim 2, wherein the first bridge polymer is a ladder-shaped bridge polymer of polyimide (PI) and a derivative thereof. The flexible battery according to claim 1, wherein when any of the first active material layer, the second active material layer, the intermediate layer, the first interface, or the second interface includes the first adhesive , Any of the remaining layers or interfaces has a second adhesive, the second adhesive includes at least a second linear polymer and at least a second crystallization inhibitor, the first adhesive and the second Then the agents are different. The flexible battery according to claim 10, wherein the second linear polymer is selected from the group consisting of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-trichloroethylene (PVDF-HFP), and polymer. Polytetrafluoroethene (PTFE), Acrylic Acid Glue, Epoxy, Polyethylene Oxide (PEO), Polyacrylonitrile (PAN), Sodium Carboxymethyl Cellulose ( carboxymethyl cellulose (CMC), styrene-butadiene (SBR), polymethylacrylate, polyacrylamide, polyvinylpyrrolidone (PVP), and combinations thereof. The flexible battery according to claim 10, wherein the second bridging polymer is selected from the group consisting of epoxy, acrylic acid, polyacrylonitrile, and a combination thereof. Network-type bridging polymers. The flexible battery according to claim 10, wherein the second bridge polymer is a ladder-shaped bridge polymer of polyimide (PI) and derivatives thereof. The flexible battery according to claim 10, wherein the first linear polymer and the second linear polymer are the same. The flexible battery according to claim 10, wherein the first bridge polymer and the second bridge polymer are the same. The flexible battery according to claim 10, wherein a weight percentage of the first bridging polymer in the first adhesive is different from a weight percentage of the second bridging polymer in the second adhesive.