KR100559364B1 - An electrode and lithium battery comprising a porous three-dimensional current collector and fabrication method thereof - Google Patents

Abstract

The present invention relates to an electrode in which an electrode active material is uniformly distributed in pores of a porous three-dimensional current collector, a lithium battery using the same, and a method of manufacturing the same. Electrode according to the present invention is excellent in conductivity, the potential distribution on the surface of the electrode is maintained constant, and the separation of the electrode active material is prevented, the utilization rate, cycle life and high rate charge and discharge characteristics of the electrode active material is excellent.

Porous 3D current collector, lithium battery, nano material, anode, cathode

Description

Electrode composed of porous three-dimensional current collector and lithium battery using same, and manufacturing method therefor {AN ELECTRODE AND LITHIUM BATTERY COMPRISING A POROUS THREE-DIMENSIONAL CURRENT COLLECTOR AND FABRICATION METHOD THEREOF}

1A and 1B are cross-sectional views of an electrode composed of a porous three-dimensional current collector of the present invention, in which the electrode active material is uniformly distributed in pores of a porous three-dimensional current collector such as copper, nickel, stainless steel, aluminum, or silver. Indicates.

Figure 2 is a graph showing the electrode capacity and the life test results of the lithium secondary battery of Examples 1, 2, 3, 4 and 5 of the present invention, and the lithium secondary battery of Comparative Example 1.

3 is a graph showing high rate discharge characteristics of the lithium secondary battery of Example 1 and the lithium secondary battery of Comparative Example 1 of the present invention.

4 is a graph showing discharge characteristics of the lithium primary battery of Example 6 and the lithium primary battery of Comparative Example 2 of the present invention.

The present invention relates to an electrode using a porous three-dimensional current collector, a lithium battery using the same, and a method of manufacturing the same. More specifically, the present invention relates to an electrode in which an electrode active material is uniformly distributed in pores of a porous three-dimensional current collector such as copper, nickel, stainless steel, aluminum, or silver, a lithium battery using the same, and a method of manufacturing the same.

Conventional lithium batteries can be roughly classified into lithium primary batteries and lithium secondary batteries. Lithium primary battery uses lithium as a negative electrode, and is divided into Li-MnO ₂ , Li- (CF) _n , Li-SOCl _2, etc. according to the type of positive electrode, and these are currently commercialized (JO Besenhard, Handbook of Battery Materials, WILEY-VCH, Weinheim (1999). Lithium primary batteries have a disadvantage in that the dislocation unevenness occurs due to the local dissolution reaction of the lithium electrode, thereby lowering the electrode utilization rate. In addition, since the anode uses an expanded foil, a punched foil, or a non-porous foil as a current collector, a two-dimensional structure, high rate discharge characteristics and utilization rates are deteriorated.

In the case of a lithium secondary battery, a battery using a carbon-based material as a negative electrode and using LiCoO ₂ or LiMn ₂ O ₄ as a positive electrode has been commercialized. However, in order to increase the performance of the battery, the production of a new electrode active material, the surface modification of the electrode active material, the performance improvement of the membrane and polymer electrolyte, the organic solvent electrolyte to increase the utilization and cycle life of the electrode active material, and to improve the high rate charge and discharge characteristics Much research has been done on the improvement of the performance.

In the case of commercially available lithium ion batteries, a thin copper current collector is used for the negative electrode, and an aluminum thin current collector is used for the positive electrode. In the case of a lithium ion polymer battery, an expanded copper foil or a punched copper foil is used for the negative electrode. In the current collector in the form of foil, a current collector in the form of expanded aluminum foil or punched aluminum foil is used for the positive electrode. These current collectors are two-dimensional current collectors, and in order to increase the binding force between the electrode active material and the current collector, a large amount of binder must be used in the manufacture of the electrode, or the surface of the current collector must be modified, and the electrode active material can be thickened. It has the same disadvantage as none. As a result, the utilization rate and cycle life of the electrode active material are exposed, and high rate charge / discharge characteristics are somewhat low, and thus improvement is necessary (D. Linden, Handbook of Batteries, McGRAW-HILL INC., New York (2002)).

The present invention is excellent in conductivity, the potential distribution of the electrode surface is kept constant, the separation of the electrode active material is prevented, the electrode excellent in the utilization rate, cycle life and high rate charge and discharge characteristics of the electrode active material, and a lithium battery using the same, and its manufacture To provide a way.

The object of the present invention as described above is achieved by providing an electrode in which the electrode active material is uniformly distributed in the pores of the porous three-dimensional current collector, a lithium battery using the same, and a method of manufacturing the same.

In the electrode of the present invention, an electrode active material is uniformly distributed in pores of a porous three-dimensional current collector such as copper, nickel, stainless steel, aluminum, or silver. The porous three-dimensional current collector is composed of Ni, Cu, SUS, Ti, V, Cr, Mn, Fe, Co, Zn, Mo, W, Ag, Au, Ru, Pt, Ir, Al, Sn, Bi and Sb It is selected from the group, and the form may be in the form of foamed metal, metal fiber, porous metal, etched metal or uneven back and forth metal. The pore size of the porous three-dimensional current collector is suitably 1 μm-10 mm.

Any active material known in the art may be used as the positive electrode active material and the negative electrode active material used for the electrode of the present invention. For example, as a cathode active material, MnO ₂ or (CF) _n is used for a lithium primary battery, and LiCoO ₂ , LiNiO ₂ , LiNiCoO ₂ , LiMn ₂ O ₄ , LiMnO ₂ , S, and LiFePO _{4 for a} lithium secondary battery. , V ₂ O ₅ or V ₆ O ₁₃ may be used, and the negative electrode active material is carbon, tin oxide, Si, Al, Sn, Bi, Sb, mixtures or compounds thereof, lithiation of these negative electrode active materials One can be used.

In the present invention, the amount of the mixture of the electrode active material, the binder and the conductive material to be filled in the porous three-dimensional current collector is preferably 70 to 95% by weight relative to the total weight of the electrode. On the other hand, the content of each component in the mixture of the electrode active material, the binder and the conductive material is suitably 70 to 99% by weight of the active material, 0.5 to 10% by weight of the binder, 0.5 to 20% by weight of the conductive material.

On the other hand, in the case of an electrode active material of nano-size material, the effect of the present invention can be increased. In the case of a nano-size active material, since the surface area of the active material per unit weight is large, and thus the amount of the conductive material and the binder is increased, the amount of the electrode active material contained in the electrode is relatively small and the resistance is large, thereby decreasing the electrode capacity. And high rate charge / discharge characteristics may fall. However, as in the present invention, when using a porous three-dimensional current collector, since the electrode can be manufactured using a small amount of binder and the electrical conduction occurs in three dimensions, the conductive material can be used less, nano-size material active material In the case of using, the electrode capacitance and the high rate charge / discharge characteristics can be improved. Therefore, when nanomaterial active materials are developed and commercialized in the future, the role of the electrode consisting of the porous three-dimensional current collector of the present invention filled with these active materials is very important and the effect will be very large. Suitable active material particles suitable for use in the present invention preferably have a size of 10 nm-100 μm .

1A and 1B show a planar cross-sectional view and a longitudinal cross-sectional view of an electrode according to the present invention, respectively. FIG. 1A shows that the electrode active material particles 1 are uniformly distributed in the pores of the porous three-dimensional current collector 2 (solid line portion). 1B shows that the electrode active material particles 3 are uniformly distributed in the pores of the porous three-dimensional current collector 4 in the form of unevenness back and forth.

Hereinafter, a method of manufacturing an electrode according to the present invention will be described. First, the electrode active material particles are pasted together with a conductive material, a binder, and a solvent, and uniformly filled in the pores of the porous three-dimensional current collector by a paste coating method. Then, it was dried and pressed using a hot roll press or a flat plate press at a pressure of 10 kg / cm 2 -100 t / cm 2 at a temperature of 80 ° C. to 150 ° C. to obtain an electrode. The solvent may be a mixture of 1-methyl-2-pyrrolidinone and acetone, but is not necessarily limited thereto.

According to the present invention, the anode active material or the cathode active material can be easily filled in the pores of the porous three-dimensional current collector, the amount of the binder used can be reduced, the content of the electrode active material in the electrode can be increased, and even the amount of the conductive material may be used. The advantage is that it can be reduced.

The electrode of the present invention has an improved electrical conductivity, thereby maintaining a constant current and potential distribution in the electrode, thereby suppressing local overcharge reactions and preventing separation of the electrode active material, thereby increasing the utilization rate and cycle life of the electrode. In batteries, the effect is greater.

Electrode according to the present invention can be used as a negative electrode and / or a positive electrode in a lithium battery using a separator such as PP (polypropylene), PE (polyethylene), lithium polymer battery using a polymer electrolyte and all-solid lithium battery using a solid electrolyte Can be.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the embodiments are only examples of the present invention, and the scope of the present invention is not limited thereto.

Example 1

6.0 g of graphite and 0.2 g of polyvinylidene fluoride (hereinafter referred to as "PVdF") are mixed with an appropriate amount of 1-methyl-2-pyrrolidinone (hereinafter referred to as "NMP") and acetone, When obtained, the paste was filled into the pores of the porous three-dimensional foamed nickel current collector and dried, followed by hot rolling to obtain a carbon cathode.

5.7 g of LiCoO ₂ , 0.6 g of acetylene black (hereinafter referred to as "AB") and 0.4 g of PVdF are mixed with an appropriate amount of NMP and acetone, and when the appropriate viscosity is obtained, the paste is added to the porous three-dimensional foamed nickel current collector. Filled in the pores, dried, and rolled to obtain a LiCoO ₂ positive electrode.

A lithium _secondary battery was formed by stacking a carbon cathode, a PP separator, and a LiCoO ₂ positive electrode, injecting an EC / EMC solution in which 1M LiPF ₆ was dissolved, and then charging and discharging rate C / 2 based on the electrode capacity and cycle life. Was investigated.

Example 2

6.0 g of graphite and 0.2 g of PVdF are mixed with an appropriate amount of NMP and acetone. When a suitable viscosity is obtained, the paste is filled into the pores of a porous three-dimensional nickel fiber current collector, dried, and then heated and rolled. A carbon cathode was obtained.

5.7 g of LiCoO ₂ , 0.6 g of AB and 0.4 g of PVdF are mixed with an appropriate amount of NMP and acetone, and when the appropriate viscosity is obtained, the paste is filled into the pores of the porous three-dimensional nickel fiber current collector and dried, followed by hot rolling To obtain a LiCoO ₂ anode.

A lithium _secondary battery was formed by stacking a carbon cathode, a PP separator, and a LiCoO ₂ positive electrode, injecting an EC / EMC solution in which 1M LiPF ₆ was dissolved, and then charging and discharging rate C / 2 based on the electrode capacity and cycle life. Was investigated.

Example 3

6.0 g of graphite and 0.2 g of PVdF are mixed with an appropriate amount of NMP and acetone, and when the appropriate viscosity is obtained, the paste is cast into the pores of the porous three-dimensional porous copper current collector prepared by electroplating and dried. Then, it was heated and rolled to obtain a carbon cathode.

5.7 g of LiCoO ₂ , 0.6 g of AB and 0.4 g of PVdF are mixed with an appropriate amount of NMP and acetone, and when the appropriate viscosity is obtained, the paste is filled into the pores of the porous three-dimensional expanded nickel current collector and dried, followed by hot rolling To obtain a LiCoO ₂ anode.

A lithium _secondary battery was formed by stacking a carbon cathode, a PP separator, and a LiCoO ₂ positive electrode, injecting an EC / EMC solution in which 1M LiPF ₆ was dissolved, and then charging and discharging rate C / 2 based on the electrode capacity and cycle life. Was investigated.

Example 4

6.0 g of graphite and 0.2 g of PVdF are mixed with an appropriate amount of NMP and acetone, and when the appropriate viscosity is obtained, the paste is cast into the pores of the porous three-dimensional etched copper current collector and dried, followed by hot rolling To obtain a carbon cathode.

5.7 g of LiCoO ₂ , 0.6 g of AB and 0.4 g of PVdF are mixed with an appropriate amount of NMP and acetone, and when the appropriate viscosity is obtained, the paste is cast into pores of the porous three-dimensional etched aluminum current collector to dry After heating, it was heated and rolled to obtain a LiCoO ₂ anode.

A lithium _secondary battery was formed by stacking a carbon cathode, a PP separator, and a LiCoO ₂ positive electrode, injecting an EC / EMC solution in which 1M LiPF ₆ was dissolved, and then charging and discharging rate C / 2 based on the electrode capacity and cycle life. Was investigated.

Example 5

6.0 g of graphite and 0.2 g of PVdF were mixed with an appropriate amount of NMP and acetone, and when the appropriate viscosity was obtained, the paste was cast back and forth in the pores of the uneven copper current collector, dried and heated and rolled to obtain a carbon cathode. .

5.7 g of LiCoO ₂ , 0.6 g of AB and 0.4 g of PVdF are mixed with an appropriate amount of NMP and acetone, and when the appropriate viscosity is obtained, the paste is cast back and forth in the pores of the uneven aluminum current collector and dried, followed by hot rolling To obtain a LiCoO ₂ anode.

A lithium _secondary battery was formed by stacking a carbon cathode, a PP separator, and a LiCoO ₂ positive electrode, injecting an EC / EMC solution in which 1M LiPF ₆ was dissolved, and then charging and discharging rate C / 2 based on the electrode capacity and cycle life. Was investigated.

Example 6

5.7 g of MnO ₂ , 0.6 g of AB and 0.4 g of PVdF are mixed with an appropriate amount of NMP and acetone, and when the appropriate viscosity is obtained, the paste is filled into the pores of the porous three-dimensional expanded nickel current collector and dried, followed by hot rolling The MnO ₂ anode was obtained.

Lithium anode, PP separator and MnO ₂ positive electrode were laminated to constitute a lithium primary battery, and after discharging the PC / EMC solution in which 1M LiPF ₆ was dissolved, the discharge characteristics were investigated at a discharge rate of C / 10.

Comparative Example 1

6.0 g of graphite and 0.2 g of PVdF were mixed with an appropriate amount of NMP and acetone. When a suitable viscosity was obtained, the paste was cast on a copper foil, dried, and then heated and rolled to obtain a carbon cathode.

5.7 g of LiCoO ₂ , 0.6 g of AB and 0.4 g of PVdF are mixed with an appropriate amount of NMP and acetone, and when the appropriate viscosity is obtained, the paste is cast into an aluminum foil, dried, and then heated and rolled to LiCoO ₂ A positive electrode was obtained.

A lithium _secondary battery was formed by stacking a carbon cathode, a PP separator, and a LiCoO ₂ positive electrode, injecting an EC / EMC solution in which 1M LiPF ₆ was dissolved, and then charging and discharging rate C / 2 based on the electrode capacity and cycle life. Was investigated.

Comparative Example 2

5.7 g of MnO ₂ , 0.6 g of AB and 0.4 g of PVdF were mixed with an appropriate amount of NMP and acetone, and when a suitable viscosity was obtained, the paste was cast on a thin aluminum sheet, dried, and then heated and rolled to obtain a MnO ₂ anode.

A lithium primary battery was formed by stacking a lithium cathode, a PP separator, and an MnO ₂ anode, and the discharge characteristics were investigated at a discharge rate of C / 10 after injecting a PC / EMC solution in which 1M LiPF ₆ was dissolved.

The electrode capacities (based on the LiCoO ₂ active material) and cycle characteristics of the lithium secondary batteries prepared in Examples 1 to 5 and Comparative Example 1 are shown in FIG. 2. From this, it can be seen that the electrode capacity and cycle life characteristics of the battery according to the present invention are superior to the battery of the comparative example.

Figure 3 shows the high rate discharge characteristics (1C) of the lithium secondary battery prepared in Example 1 and Comparative Example 1, the high rate discharge characteristics of the lithium secondary battery of Example 1 of the present invention is superior to the battery of Comparative Example 1 You can see that.

Figure 4 shows the discharge characteristics (0.1C) of the lithium primary battery prepared in Example 6 and Comparative Example 2, it can be seen that the discharge characteristics of the battery of Example 1 of the present invention is superior to the battery of Comparative Example 2 Can be.

According to the present invention, an electrode in which an electrode active material is uniformly distributed in pores of a porous three-dimensional current collector, a lithium battery using the same, and a method of manufacturing the same are provided. Electrode according to the present invention is excellent in electrode utilization, cycle life and high rate charge and discharge characteristics, can be applied to various industrial fields, such as for various small electronic devices, communication equipment and power supply of electric vehicles, localization, import replacement and export of various devices Increase effect can be achieved.

Claims (15)

A positive electrode for a lithium battery, wherein a mixture of a positive electrode active material, a binder, and a conductive material is uniformly filled in pores of a porous three-dimensional current collector. The positive electrode for a lithium battery according to claim 1, wherein a content of the mixture of the positive electrode active material, the binder, and the conductive material is 70 to 95 wt% based on the total weight of the positive electrode. The positive electrode for a lithium battery according to claim 1, wherein the content of the active material, the binder, and the conductive material in the mixture of the positive electrode active material, the binder, and the conductive material is 70-99 wt%, 0.5-10 wt%, and 0.5-20 wt%, respectively. The positive electrode for a lithium battery according to claim 1, wherein the porous three-dimensional current collector is in the form of a foamed metal, a metal fiber, a porous metal, an etched metal, or an uneven metal back and forth. According to claim 1, wherein the material of the porous three-dimensional current collector is Ni, Cu, SUS, Ti, V, Cr, Mn, Fe, Co, Zn, Mo, W, Ag, Au, Ru, Pt, Ir, Al , Sn, Bi and Sb is selected from the group consisting of a positive electrode for a lithium battery. The positive electrode for a lithium battery according to claim 1, wherein the positive electrode active material is a positive electrode active material for a lithium primary battery selected from the group consisting of MnO ₂ and (CF) _n . The lithium secondary battery of claim 1, wherein the cathode active material is selected from the group consisting of LiCoO ₂ , LiNiO ₂ , LiNiCoO ₂ , LiMn ₂ O ₄ , LiMnO ₂ , S, LiFePO ₄ , V ₂ O _5, and V ₆ O ₁₃ . A lithium battery positive electrode which is a positive electrode active material. delete The method of claim 1, wherein the mixture of the positive electrode active material, the conductive material and the binder, or the mixture of the positive electrode active material and the binder is pasted into a uniform state using a solvent, filled in the pores of the porous three-dimensional current collector, and then dried and hot pressed. A method for manufacturing a cathode for a lithium battery according to any one of claims 7 to 9. 10. The method of claim 9, wherein the hot pressing is performed at a pressure of 10 kg / cm 2 -100 t / cm 2 using a roll press or a flat press at a temperature of 80 ° C-150 ° C. A lithium battery comprising the positive electrode according to any one of claims 1 to 7. The lithium battery according to claim 11, which is a lithium battery using a PP or PE separator, a lithium polymer battery using a polymer electrolyte, or an all-solid lithium battery using a solid electrolyte. A lithium primary battery comprising a lithium cathode, a separator and a cathode according to claim 6 laminated. A lithium secondary battery comprising a carbon cathode, a separator and a cathode according to claim 7 laminated. Cathode, separator and LiCoO ₂ , LiNiO ₂ , LiNiCoO ₂ , including a negative electrode active material selected from the group consisting of carbon, tin oxide, Si, Al, Sn, Bi, Sb, mixtures and compounds thereof and lithiated thereof LiMn ₂ O ₄ , LiMnO ₂ , S, LiFePO ₄ , V ₂ O ₅ And V ₆ O _{13 A} lithium secondary battery comprising a laminated positive electrode comprising a positive electrode active material selected from the group consisting of.

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