TWI661592B - Secondary battery and manufacturing method thereof - Google Patents

Abstract

A secondary battery includes: a positive electrode, the positive electrode including a first current collector, a positive electrode active material layer disposed on one side of the first current collector, and a first current collector and A first carbon material layer between the positive electrode active material layer; a negative electrode disposed separately from the positive electrode, including a second current collector and a plurality of superimposed on one side of the second current collector and A composite layer formed by a physical vapor deposition method, each of which includes a second carbon material layer and a silicon-containing material layer disposed on the second carbon material layer; and a sandwich between the positive electrode and the positive electrode A separator between the negative electrodes.

Description

Secondary battery and manufacturing method thereof

The present invention relates to a secondary battery, and more particularly to a lithium battery with increased volume capacity.

Secondary battery refers to a kind of battery that can be recharged and reused after power consumption is completed, including lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and lithium batteries. In recent years, the use of lithium batteries has become the mainstream. At present, the application of secondary batteries is mainly concentrated in electronic devices, and can also be used in the fields of energy storage and power batteries, such as electric vehicles, large uninterruptible power supply (UPS), and even aerospace devices.

However, with the advancement of science and technology, the demand for electrical capacity of electronic devices has also increased compared to the past, resulting in the existing secondary batteries gradually failing to meet their needs. Many research teams have begun research to increase the capacity of secondary batteries.

The use of a negative electrode containing silicon particles is a method to increase the volume capacity. For example, the Republic of China Invention Patent Publication No. 567633 proposes an electrode material for a rechargeable lithium battery. The silicon base material powder with a specific particle size range and After mixing carbon powder, transition metal powder, tin powder, water, organic solvent, polymer, polymer monomer and other materials as an additive to form a negative electrode material fine powder, the negative electrode material powder is mixed with a binder and a solvent. A negative electrode layer is obtained by forming a paste, coating the current collector and drying it.

However, during the charge and discharge process, silicon will produce a large volume change, and the solid electrolyte interface film (SEI) formed on the silicon surface will be easily cracked and peeled off, causing the silicon particles to become smaller and smaller as the number of cycles increases. Moreover, the volume capacitance is relatively reduced, and the effect of adding silicon particles is lost. Disadvantages such as this limit the application range of this type of electrode. Therefore, there is an urgent need for a secondary battery that can improve the foregoing problems and increase the volumetric capacity.

The main purpose of the present invention is to solve the problem that the conventional secondary battery using a silicon-containing electrode material has insufficient volume capacity.

To achieve the above object, the present invention provides a secondary battery having a special positive electrode and negative electrode structure. Specifically, the secondary battery of the present invention includes a positive electrode including a first current collector, a positive electrode active material layer disposed on one side of the first current collector, and a first electrode disposed on the first current collector. A first carbon material layer between a current collector and the positive electrode active material layer; a negative electrode provided separately from the positive electrode, including a second current collector and a plurality of superimposed on the second current collector; A composite layer sequentially formed on one side of the device by a physical vapor deposition method, each composite layer including a second carbon material layer and a silicon-containing material layer disposed on the second carbon material layer; and a clip An isolation film provided between the positive electrode and the negative electrode.

The invention also provides a method for manufacturing a secondary battery, including:

Step A1: providing a first current collector and a second current collector;

Step A2: coating a first carbon material layer and a positive electrode active material layer on one side of the first current collector, so that the first carbon material layer is disposed on the first current collector and the positive electrode active material A positive electrode was prepared between the layers, and a negative electrode was prepared by forming a plurality of stacked layers on top of each other on the side of the second current collector by a physical vapor deposition method. Including a second carbon material layer and a silicon-containing material layer disposed on the second carbon material layer;

Step A3: A separator is interposed between the positive electrode and the negative electrode, and an electrolyte is added to prepare a secondary battery.

Therefore, compared with the conventional technology, the effect that the present invention can achieve is that by using the structure of the composite layer formed by the physical vapor deposition method, the weight and volume of the active material in the secondary battery can be reduced, and the efficiency can be improved. The gram capacitance and volume capacitance reduce the contact resistance between the positive electrode active material layer and the first current collector.

The detailed description and technical contents of the present invention are described below with reference to the drawings:

[Figure 1] is a schematic cross-sectional view of a secondary battery according to an embodiment of the present invention. The secondary battery 1 includes a positive electrode 11, a negative electrode 12, and an isolation film 13. The negative electrode 12 is disposed separately from the positive electrode 11. The isolation film 13 is sandwiched between the positive electrode 11 and the negative electrode 12 and is in contact with the positive electrode 11 and the negative electrode 12 respectively. The positive electrode 11 includes a first current collector 111 and a positive electrode. An electrode active material layer 112 and a first carbon material layer 113, the positive electrode active material layer 112 is disposed on a side of the first current collector 111, and the first carbon material layer 113 is disposed on the first current collector 111 and Between the positive electrode active material layer 112, the material of the first current collector 111 can be a metal with high conductivity and does not exhibit activity to the battery reaction, such as aluminum, copper, iron, nickel, platinum, tungsten, molybdenum, tantalum , Niobium, vanadium, chromium, titanium, or zirconium, the material of the positive electrode active material layer 112 can be a commonly used transition metal oxide, such as lithium iron phosphate, lithium nickel cobalt, lithium nickel cobalt manganese, lithium cobaltate, nickel Lithium acid, lithium manganate, etc., and others that can be used as the material of the positive electrode active material layer 112 Is an iron oxides including other metal oxides, and the like, the material of the first carbon material layer 113 may be pure carbon, graphite, graphene, or a combination thereof.

The negative electrode 12 includes a second current collector 121 and a plurality of composite layers 122 stacked on one side of the second current collector 121. The material of the second current collector 121 can be a high conductivity and Metals that do not exhibit activity in battery reactions, such as aluminum, copper, iron, nickel, platinum, tungsten, molybdenum, tantalum, niobium, vanadium, chromium, titanium, or zirconium. In the present invention, the composite layer 122 is formed by a physical vapor deposition method. For example, the composite layer 122 may be a sputtering method, an electron beam evaporation method, or a vacuum arc deposition method. Vacuum arc deposition), each of the composite layers 122 includes a second carbon material layer (not shown in FIG. 1) and a silicon-containing material layer disposed on the second carbon material layer (not shown in FIG. 1) . The number of layers n of the composite layer 122 can be adjusted according to actual conditions. For example, n can be between 2 and 30, preferably between 3 and 20, and more preferably between 3 and 15. Integer. If the number of the composite layer 122 is too small, the capacitance cannot be effectively improved. On the other hand, if the number of the composite layer 122 is too large, the composite layer 122 may be easily caused by an internal stress caused when the composite layer 122 is formed into a film. Peeling occurs.

First embodiment

Please refer to "FIG. 2", which is a schematic structural diagram of a secondary battery according to a first embodiment of the present invention. In the first embodiment, the secondary battery 2 includes a positive electrode 21, a negative electrode 22, and a separation film 23. The negative electrode 22 is separated from the positive electrode 21, and the separation film 23 is sandwiched between the positive electrode 21 and the negative electrode 22 and is in contact with the positive electrode 21 and the negative electrode 22, respectively. The positive electrode 21 includes A first current collector 211, a positive electrode active material layer 212, and a first carbon material layer 213. The positive electrode active material layer 212 is disposed on the side of the first current collector 211, and the first carbon material layer 213 It is disposed between the first current collector 211 and the positive electrode active material layer 212. The negative electrode 22 includes a second current collector 221 and a plurality of composites stacked on one side of the second current collector 221. Layer 222. Each of the composite layers 222 includes a second carbon material layer 2221 and a silicon-containing material layer 2222 which are independent of each other. In this embodiment, both the second carbon material layer 2221 and the silicon-containing material layer 2222 are single. The sheet-like structure is stacked on one side of the second current collector 221 with three layers, and the second carbon material layer 2221 and the second carbon material layer 2221 adjacent to the composite layer 222 disposed on the second current collector 221 are adjacent to each other. The second current collector 221 is in contact.

In this embodiment, the negative electrode 22 further includes a third carbon material layer 223 formed on a side of the composite layer 222 away from the second current collector 221 such that the third carbon One side of the material layer 223 is in contact with the isolation film 23, and the other side is in contact with the adjacent silicon-containing material layer 2222. At this time, each of the silicon-containing material layers 2222 is sandwiched between the adjacent second carbon material layers 2221 or between the second carbon material layer 2221 and the third carbon material layer 223.

The second carbon material layer 2221, the silicon-containing material layer 2222, and the third carbon material layer 223 can be obtained by the foregoing sputtering method, the electron beam evaporation method, or the vacuum arc plating method, and The composite layers 222 are stacked to form a stack. The thickness of each of the second carbon material layer 2221, the silicon-containing material layer 2222, and the third carbon material layer 223 is independently between 10 nanometers (nm) and 200 nanometers (nm), preferably Between 50 nanometers (nm) and 100 nanometers (nm), if the thickness of the second carbon material layer 2221, the silicon-containing material layer 2222, and the third carbon material layer 223 is too thick, there is a fear of these materials. The film formation time of the layer is too long without economic benefits, and the thicker the thickness, the larger the internal stress and the unevenness, which may cause peeling. Otherwise, the second carbon material layer 2221, the silicon-containing material layer 2222, and the If the third carbon material layer 223 is too thin, it may not be enough to achieve the effect of effectively increasing the capacity of the secondary battery.

Second embodiment

Please refer to "FIG. 3", which is a schematic structural diagram of a secondary battery 3 according to a second embodiment of the present invention. In the second embodiment, the secondary battery 3 includes a positive electrode 31, a negative electrode 32, and a separator 33. The negative electrode 32 is separated from the positive electrode 31, and the separation film 33 is sandwiched between the positive electrode 31 and the negative electrode 32 and is in contact with the positive electrode 31 and the negative electrode 32, respectively. The positive electrode 31 It includes a first current collector 311, a positive electrode active material layer 312, and a first carbon material layer 313. The positive electrode active material layer 312 is disposed on the side of the first current collector 311, and the first carbon material layer 313 is disposed between the first current collector 311 and the positive electrode active material layer 312; the negative electrode 32 includes a second current collector 321 and a plurality of layers stacked on one side of the second current collector 321. Composite layer 322.

The composite layer 322 includes a second carbon material layer 3221 and a silicon-containing material layer 3222. The silicon-containing material layer 3222 is a patterned structure, such as a strip extending in a vertical direction, and is different from the foregoing. The single sheet structure of the first embodiment. The negative electrode 32 further includes a third carbon material layer 323 formed on a side of the composite layer 322 away from the second current collector 321 such that one side of the third carbon material layer 323 It is in contact with the isolation film 33. At this time, each of the silicon-containing material layers 3222 is sandwiched between the adjacent second carbon material layers 3221 or between the second carbon material layer 3221 and the third carbon material layer 323.

With this structure, more channels can be provided for an electrolyte to penetrate into the negative electrode 32, thereby avoiding the problem that the silicon battery-containing material layer 3222 of the negative electrode 32 is cracked and peeled off, causing the secondary battery to fail quickly. Accordingly, the effect of reducing the waste of ineffective space and effectively reducing the volume of the negative electrode 32 is achieved, and the electrolyte can be flow-exchanged through the pores between the patterned silicon-containing material layers 3222.

Hereinafter, a method for manufacturing the secondary battery having the above structure will be described in detail.

Please refer to "Fig. 4", taking the manufacturing method of the secondary battery 2 in the first embodiment of the "Fig. 2" of the present invention as an example for explanation. For the material selection of each component, refer to the description of the foregoing embodiment. No longer. The production method includes the following steps:

Step A1: Provide a first current collector 211 and a second current collector 221.

Step A2: A first carbon material layer 213 and a positive electrode active material layer 212 are coated on one side of the first current collector 211, so that the first carbon material layer 213 is disposed on the first current collector 211 and A positive electrode 21 is formed between the positive electrode active material layers 212. In step A2, the first carbon material layer 213 and the positive electrode active material layer 212 may be coated on one side of the first current collector 211, for example, the first carbon material layer 213 is coated first, and After being dried, the positive electrode active material layer 212 is coated on the first carbon material layer 213; coating of the first carbon material layer 213 and the positive electrode active material layer 212 can also be performed at the same time, so that the first The carbon material layer 213 and the positive electrode active material layer 212 diffuse with each other at the interface to form a gradient change. Because there is no interface between the first carbon material layer 213 and the positive electrode active material layer 212 during simultaneous coating, the method of simultaneous coating is preferred in the present invention.

A negative electrode 22 is formed by forming a plurality of stacked composite layers 222 on one side of the second current collector 221 by a physical vapor deposition method. Each of the composite layers 222 includes a second carbon. The material layer 2221 and a silicon-containing material layer 2222 disposed on the second carbon material layer 2221. The physical vapor deposition method may be a sputtering method, an electron beam evaporation method, or a vacuum arc plating method.

In the present invention, the manufacturing order of the positive electrode 21 and the negative electrode 22 is not particularly limited, and the negative electrode 22 may be manufactured first, and then the positive electrode 21 may be manufactured.

Step A3: An isolation film 23 is interposed between the positive electrode 21 and the negative electrode 22. For example, a membrane having a pore structure, such as a non-woven fabric or a porous membrane of a polymer, can be selected and used as the separator 23, and the present invention is not particularly limited thereto.

After step A2, a step A2-1 is further included. A third carbon material layer 223 is formed on a side of the composite layer 222 away from the second current collector 221, so that one of the third carbon material layers 223 is formed. The side is in contact with the isolation film 23. The third carbon material layer 223 may be formed of pure carbon, graphite, graphene, or a combination thereof. In addition, after step A3, a lithium salt-containing electrolyte is added to obtain a secondary battery 2 having a structure as shown in FIG. 2.

If the secondary battery 3 of the second embodiment is to be manufactured, a mask is further used to pattern the silicon-containing material layer 3222 during the process of forming the composite layer 222 by the physical vapor deposition method, and the remaining steps are all It is the same as the foregoing, and is not repeated here.

In order to verify the technical effect of the secondary battery of the present invention, the inventor took a conventional secondary battery as a comparative example, and tested and compared it with the secondary battery 2 of the first embodiment of the present invention. The secondary battery 2 according to the first embodiment of the present invention is formed by a slurry coating method. The composite layer 222 of the negative electrode 22 is formed by the physical vapor deposition method, and the silicon-containing material layer 2222 is used. The weight of the two active materials, the volume of the active materials, the gram capacity, the volume capacity, the Coulombic efficiency and the Recyclable efficiency are shown in Table 1 below. Here, the active material refers to the first carbon material layer 213, the positive electrode active material layer 212, and the composite layer 222; the Coulomb efficiency is the first discharge capacity divided by the first charge capacity; the cycle efficiency is the second The discharge capacity is divided by the first discharge capacity, and the charge and discharge cycle is performed 100 times to observe the percentage decline of the capacity to infer its service life. Table 1

As can be seen from Table 1 above, compared with the conventional secondary battery, the secondary battery 2 of the first embodiment of the present invention not only reduces the weight of the active material by about 50%, but also significantly reduces the volume of the active material to 0.003 to 0.006. cm ³ . The secondary battery 2 of the first embodiment of the present invention is superior to conventional secondary batteries in terms of gram capacity and volume capacity, and particularly has a very significant improvement in volume capacity. In addition, compared with the conventional secondary battery, the Coulomb efficiency and cycle efficiency of the first embodiment of the present invention are not deteriorated or reduced.

Therefore, the composite layer formed by the physical vapor deposition method in the present invention can reduce the weight and volume of the active material in the secondary battery of the present invention, reduce the material volume of the negative electrode by 50% to 90%, and increase the gram. The capacitance and volume capacitance reduce the contact resistance between the positive electrode active material layer and the first current collector at the same time; and it does not sacrifice Coulomb efficiency and cycle efficiency.

It is added that the ordinal number before the element or step, such as "first", "second", "third", etc., is for the convenience of description, so that those with ordinary knowledge in the art can understand the present invention, the ordinal number "First," "second," "third," etc. are not intended to restrict the order or content of use. For example, the "first carbon material layer", the "second carbon material layer", and the "third carbon material layer" are only used to represent different carbon material layers, but the compositions forming the carbon material layers may be the same as each other. Or different. In addition, the thickness of each layer of the secondary battery illustrated in FIG. 1, FIG. 2, and FIG. 3 is for convenience of explanation only, and is not intended to limit the relationship between the thickness and thickness of each layer. Those with ordinary knowledge in the field may According to the actual situation, make appropriate adjustments on the premise that the scope of patent application of the present invention is not exceeded.

The present invention has been described in detail above, but the above is only a preferred embodiment of the present invention, and the scope of implementation of the present invention cannot be limited. That is, all equivalent changes and modifications made in accordance with the scope of the application of the present invention should still fall within the scope of the patent of the present invention.

1, 2, 3‧‧‧ secondary batteries

11, 21, 31‧‧‧ positive electrode

111, 211, 311‧‧‧‧First current collector

112, 212, 312‧‧‧ positive electrode active material layer

113, 213, 313‧‧‧ first carbon material layer

12, 22, 32‧‧‧ negative electrode

121, 221, 321‧‧‧Second current collector

122, 222, 322‧‧‧ composite layer

2221, 3221‧‧‧Second carbon material layer

2222, 3222‧‧‧ Silicon-containing material layer

13, 23, 33‧‧‧Isolation film

323, 223‧‧‧ Third carbon material layer

A1, A2, A3 ‧‧‧ steps

[Fig. 1] is a schematic cross-sectional view of a secondary battery according to an embodiment of the present invention. [Fig. 2] is a schematic structural diagram of a secondary battery according to the first embodiment of the present invention. [Figure 3] is a schematic structural diagram of a secondary battery according to a second embodiment of the present invention. [Fig. 4] is a schematic flow chart of manufacturing steps of a secondary battery according to an embodiment of the present invention.

Claims (9)

A secondary battery includes: a positive electrode, the positive electrode including a first current collector, a positive electrode active material layer disposed on one side of the first current collector, and a first current collector and A first carbon material layer between the positive electrode active material layer; a negative electrode disposed separately from the positive electrode, including a second current collector and a plurality of superimposed on one side of the second current collector and A composite layer sequentially formed by a physical vapor deposition method, each composite layer including a second carbon material layer and a silicon-containing material layer disposed on the second carbon material layer, wherein each of the second carbons The thickness of the material layer and the silicon-containing material layer are each independently between 10 nanometers (nm) and 200 nanometers (nm); and an isolation film sandwiched between the positive electrode and the negative electrode; wherein, The second current collector is in direct contact with the second carbon material layer closest to the composite layer of the second current collector. The secondary battery according to item 1 of the patent application scope, wherein the negative electrode further includes a third carbon material layer disposed on one side of the composite layer away from the second current collector, and the third carbon material The layer side is in contact with the isolation film. The secondary battery according to item 1 of the scope of patent application, wherein the number of layers of the composite layer is between 2 and 30. The secondary battery according to item 1 of the scope of patent application, wherein the silicon-containing material layer has a single sheet structure. The secondary battery according to item 1 of the patent application scope, wherein the silicon-containing material layer has a patterned structure. A method for manufacturing a secondary battery includes: step A1: providing a first current collector and a second current collector; step A2: coating a first carbon material layer on one side of the first current collector and A positive electrode active material layer, the first carbon material layer is disposed between the first current collector and the positive electrode active material layer to prepare a positive electrode, and a physical vapor deposition method is used on the second set A negative electrode is prepared by forming a plurality of stacked composite layers on one side of the flow device, wherein each of the composite layers includes a second carbon material layer and a silicon-containing material disposed on the second carbon material layer. Layer, so that the second current collector is in direct contact with the second carbon material layer closest to the composite layer of the second current collector, wherein each of the second carbon material layer and the silicon-containing material layer The thickness is independently between 10 nanometers (nm) and 200 nanometers (nm); Step A3: a separator is interposed between the positive electrode and the negative electrode and an electrolyte is added to prepare a secondary battery . According to the method described in item 6 of the scope of patent application, after step A2, a step A2-1 is further included, and a third carbon material layer is formed on one side of the composite layer away from the second current collector. According to the method described in item 6 of the patent application scope, in step A2, a mask is further used to pattern the silicon-containing material layer. According to the method described in item 6 of the patent application scope, the physical vapor deposition method formed in step A2 is selected from the group consisting of a sputtering method, an electron beam evaporation method, and a vacuum arc plating method.