KR100888287B1 - Secondary Battery Containing Inactivity Powder for Electrolyte - Google Patents

Abstract

The present invention relates to a secondary battery in which an electrode assembly capable of repeatedly charging and discharging is embedded in a battery case in which an electrolyte solution is impregnated, wherein an electrolyte inert powder is filled in a space between the electrode assembly and the battery case and / or an electrode. It provides a secondary battery which is coated on the outer circumferential surface of the assembly, the secondary battery can prevent the thermal contraction phenomenon of the separator due to the charge and discharge, can suppress deformation or penetration to the external impact, etc. It has the effect of absorbing external shocks.

Description

Secondary Battery Containing Electrolyte Inert Powder {Secondary Battery Containing Inactivity Powder for Electrolyte}

1 is a front perspective view of a pouch type secondary battery according to an exemplary embodiment of the present invention.

The present invention relates to a secondary battery containing an electrolyte inert powder, and more particularly, a secondary battery in which an electrode assembly capable of repeated charging and discharging is embedded in a battery case impregnated with an electrolyte solution. A secondary battery is provided, which is filled in a space between the electrode assembly and the battery case and / or is coated on an outer circumferential surface of the electrode assembly.

As the development and demand for mobile devices increases, the demand for secondary batteries as energy sources is increasing rapidly. Among them, many researches on lithium secondary batteries with high energy density and discharge voltage have been conducted and commercialized. It is widely used.

Lithium secondary batteries are classified into a rectangular or cylindrical secondary battery in which the electrode assembly is built in a rectangular or cylindrical aluminum can in shape, and a pouch type secondary battery in which the electrode assembly is embedded in a laminate sheet composed of a metal layer and a resin layer.

In general, in the secondary battery, the electrode assembly has a structure in which the electrode assembly is wound or laminated after a separator having a size slightly larger than the electrodes between the positive electrode and the negative electrode, and in order to suppress dendritic growth due to precipitation of lithium metal, A rather large cathode is used. That is, the outer circumferential surface of the electrode assembly is formed to protrude in the order of the separator> anode> anode.

Since the secondary battery including the electrode assembly is manufactured by mounting an electrode assembly as described above in a battery case of a can or pouch and injecting an electrolyte, there is some space between the electrode assembly and the battery case.

By such a space, the secondary battery has a problem that the electrode assembly is moved when an external shock such as shock or vibration is applied, thereby causing a short circuit inside the battery. In particular, the pouch-type secondary battery is made of a pouch-type battery case of weak mechanical rigidity, it is very likely to be easily deformed by external shock, dropping, etc., causing an internal short circuit.

On the other hand, Japanese Patent Application Laid-Open No. 2004-356047 includes a reinforcing agent of a metal or organic polymer in the core of a jelly-roll type electrode assembly in order to prevent deformation of the secondary battery due to expansion and contraction of the negative electrode repeated during charging and discharging. have. The above technique is effective in improving safety by suppressing deformation of a battery by chemical reaction, but has a disadvantage in that a separate device or an additional material must be installed in order to improve safety by preventing deformation due to external shock.

Therefore, there is a high demand for a technology capable of improving the safety of the battery by suppressing deformation caused by internal battery reaction as well as deformation caused by external shock.

The present invention aims to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

The present inventors, after in-depth study and various experiments, after filling or applying the electrolyte inert powder to a predetermined portion inside the battery, and manufacturing the secondary battery by injecting the electrolyte, the electrolyte inert powder is To prevent the heat shrinkage of the separator by the charge and discharge, to suppress deformation or penetration through external impact, and to absorb the external impact, to confirm the advantages of improving the electrochemical and physical safety of the battery, the present invention Came to complete.

Accordingly, the secondary battery according to the present invention is a secondary battery in which an electrode assembly capable of repeated charging and discharging is embedded in a battery case in a state in which an electrolyte solution is impregnated, and an electrolyte inert powder is disposed in a space between the electrode assembly and the battery case. And is applied on the outer circumferential surface of the electrode assembly.

When the electrolyte inert powder is filled or coated in a predetermined amount in the inside of the battery, a fine gap formed between the powders acts as a damping part of the external force, thereby buffering when an impact is applied, and emptying the inside of the battery. By filling the space, not only the electrode assembly can be prevented from moving, but also the heat shrinkage phenomenon of the separator due to heat generated during charging and discharging inside the porous separator can be suppressed. In addition, since it does not react directly with the materials inside the battery, in particular the electrolyte, it does not cause additional physicochemical action such as by-product generation, volume expansion, etc. has the advantage that does not adversely affect the operation performance of the battery.

The electrolyte inert powder is not particularly limited as long as the electrolyte inert powder can absorb external shocks, fill empty spaces, and suppress movement of materials within the battery. However, the electrolyte inert powder is 50 μm to 1 in consideration of problems in the battery manufacturing process. It is preferable to have a particle diameter of mm.

In addition, the kind of powder is not particularly limited as long as it is a material that does not react with an electrolyte, particularly, an electrolyte, and may be an inorganic powder. Examples of such inorganic powders include SiO ₂ , TiO ₂ , Al ₂ O ₃ , ZrO ₂ , SnO ₂ , CeO ₂ , MgO, CaO, ZnO, Y ₂ O ₃ , Pb (Zr, Ti) O ₃ (PZT), Pb _1-x La _x Zr _1-y Ti _y O ₃ (PLZT), PB (Mg ₃ Nb _2/3 ) O ₃ -PbTiO ₃ (PMN-PT), BaTiO there may be mentioned _{3, hafnia (HfO 2),} SrTiO 3 , and combinations of two or more thereof and the like. In particular, a hygroscopic inorganic powder which can inhale a predetermined amount of electrolyte is more preferable.

In one preferred example, the electrode assembly may have a separator that extends longer than the anode and the cathode on its outer circumferential surface, and an electrolyte inert powder may be coated on at least a portion of the separator extension. In this case, the outer peripheral surface of the separator to which the electrolyte inert powder is applied may be the entire extended portion of the separator.

In the above structure, the electrolyte inert powder may be applied to the corresponding site by a binder as an adhesive component, and the binder is the same as the binder added to the electrode (a kind of binder) or may be used as the binder. It may be one of them, representative examples thereof include PVDF, PTFE, SBR, high polymerization degree polyvinyl alcohol and the like.

The electrode assembly is not particularly limited as long as it is a structure that connects a plurality of electrode tabs to form a positive electrode and a negative electrode, and is preferably a stack type in which a plurality of positive and negative electrodes having a predetermined size are stacked with a separator interposed therebetween. Or a stack / foldable structure. Details of the electrode assembly of the stack / foldable structure are disclosed in Korean Patent Application Publication Nos. 2001-0082058, 2001-0082059, and 2001-0082060, which are described in the context of the present invention. Incorporated by reference.

The secondary battery according to the present invention is applied to a laminate sheet including a metal layer and a resin layer, specifically, a pouch type secondary battery in which an electrode assembly is built in a pouch type case of an aluminum laminate sheet, or a metal can, specifically, an aluminum square Alternatively, the present invention may be applied to a rectangular or cylindrical secondary battery in which an electrode assembly is embedded in a cylindrical can. Especially, it can be preferably applied to a pouch type secondary battery.

In another aspect, the present invention, the electrode assembly of the positive electrode / separator / negative electrode structure is mounted to the housing of the battery case, and after filling the filler and / or coating liquid containing the electrolyte inert powder between the electrode assembly and the battery case, The present invention relates to a lithium secondary battery prepared by injecting an electrolyte and a method of manufacturing the same.

1 schematically illustrates a front perspective view of a pouch type secondary battery according to one embodiment of the present invention. In FIG. 1, a pouch type secondary battery is selected as an example to describe the present invention in more detail, but the scope of the present invention is not limited to the pouch type secondary battery.

Referring to FIG. 1, the pouch type secondary battery 100 includes an electrode assembly 200 in which electrode tabs or leads 211 and 221 protrude from one side, and is embedded in the pouch type battery case 300, and the electrode assembly 200. ) And the inorganic powder 400 is filled in the space 320 of the battery case 300, and then an electrolyte (not shown) is injected to seal the battery case 200.

The electrode assembly 200 is a stacked structure in which the anode 210, the cathode (not shown), and the separator 230 are sequentially stacked. The electrode assembly 200 uses a separator 230 having a somewhat larger size than the electrode 220. 230 defines an extension 231 along its outer circumferential surface. Although not shown in the figure, a part of the inorganic powder 400 filled in the separation space 320 of the electrode assembly 200 and the battery case 300 may be previously applied to the separator extension part 231.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are provided to illustrate the present invention, and the scope of the present invention is not limited thereto.

Example 1

The positive electrode was mixed with PVDF, which is a binder, and carbon black, which is a conductive agent, in a composition ratio of 85: 5: 10, stirred with NMP for 2 hours, coated on Al foil as a current collector, and then dried at 120 ° C. for 2 hours. It was prepared by.

The negative electrode was mixed with PVDF, a binder, and carbon black, a conductive material, in a composition ratio of 93: 6: 1, stirred with NMP for 2 hours, coated on Cu foil as a current collector, and then dried at 120 ° C for 2 hours. It was prepared by.

As described above, a porous polyethylene film (Celgard ^TM ) was sequentially laminated as a positive electrode, a negative electrode, and a separator to assemble a stacked electrode assembly, and then mounted in a pouch type battery case of an aluminum laminate sheet, as shown in FIG. 1. The battery was manufactured by filling silica powder having an average particle diameter of 200 μm into the space between the electrode assembly and the battery case, injecting an electrolyte solution, and sealing the battery case.

Comparative Example 1

A battery was manufactured in the same manner as in Example 1, except that the silica powder was not filled.

Experimental Example 1

The 20 cells prepared in Example 1 and Comparative Example 1 were charged with CC (850 mA), CV (4.25 V, 20 mA), heated to 5 ° C / min inside a hotbox, and maintained for 10 minutes.

 Tested under the conditions, the results are shown in Table 1 below.

TABLE 1

As shown in Table 1, the batteries of Example 1 according to the present invention did not cause a short circuit in the batteries in the charge and discharge experiment. That is, the silica powder, which is filled in the space between the electrode assembly and the battery case, penetrates into the porous separator to prevent thermal contraction, thereby preventing short circuits even during repeated charging and discharging. On the other hand, the cells of Comparative Example 1 were short-circuited in 3 out of 20 cells.

Experimental Example 2

20 batteries prepared in Example 1 and Comparative Example 1 were subjected to a battery drop test, and the results are shown in Table 2 below. In this experiment, 20 cells were repeatedly performed, and the drop test was performed 20 times in the direction of the terminal and 20 times in the corner direction at a height of 1.5 m.

TABLE 2

As shown in Table 2, the cells of Example 1 according to the present invention did not cause a short circuit in all 20 cells in the drop test. That is, it was confirmed that the silica powder filled in the space between the electrode assembly and the battery case absorbs the shock and prevents the movement of the electrode assembly, thereby causing a short circuit during the fall. On the other hand, the batteries of Comparative Example 1 were short-circuited in many batteries.

As described above, the secondary battery according to the present invention can prevent thermal contraction of the separator due to charge and discharge, can suppress deformation or penetration through external impact, and absorb the external impact to improve the safety of the battery. It can greatly improve.

Those skilled in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Claims (11)

An electrode assembly capable of repetitive charging and discharging is a secondary battery embedded in a battery case in which an electrolyte solution is impregnated with an electrolyte inert powder filled in (i) a space between the electrode assembly and the battery case, or ( ii) coated on the outer circumferential surface of the electrode assembly, or (iii) filled in the space between the electrode assembly and the battery case and simultaneously coated on the outer circumferential surface of the electrode assembly. The secondary battery of claim 1, wherein the electrolyte inert powder has a particle diameter of 50 μm to 1 mm. The secondary battery of claim 1, wherein the electrolyte inert powder is an inorganic powder. The secondary battery of claim 3, wherein the inorganic powder is an electrolyte hygroscopic powder. The method of claim 3, wherein the inorganic powder is SiO ₂ , TiO ₂ , Al ₂ O ₃ , ZrO ₂ , SnO ₂ , CeO ₂ , MgO, CaO, ZnO, Y ₂ O ₃ , Pb (Zr, Ti) O ₃ (PZT), Pb _1-x La _x Zr _1-y Ti _y O ₃ (PLZT), PB (Mg ₃ Nb _2/3 ) O ₃ -PbTiO ₃ (PMN-PT), A secondary battery characterized in that one or more selected from the group consisting of BaTiO ₃ , hafnia (HfO ₂ ), SrTiO ₃ and two or more thereof. The secondary battery of claim 1, wherein the separation membrane extends longer than the positive electrode and the negative electrode on the outer circumferential surface of the electrode assembly, and at least a part of the electrolyte inert powder is coated on the extension portion of the separator. The secondary battery according to claim 1, wherein the electrolyte inert powder is applied to the corresponding site by one or two or more binders selected from the group consisting of PVDF, PTFE, SBR, and high polymerization polyvinyl alcohol. The secondary battery of claim 1, wherein the electrode assembly has a stack type or a stack / fold type structure in which a plurality of positive and negative electrodes having a predetermined size are stacked with a separator interposed therebetween. The secondary battery of claim 1, wherein the battery case is formed of a laminate sheet including a metal layer and a resin layer. The secondary battery of claim 9, wherein the battery case is a pouch type case of an aluminum laminate sheet. The electrode assembly having a positive electrode / membrane / cathode structure is mounted on the housing of the battery case, and the (i) filling solution containing the electrolyte inert powder, or (ii) the coating liquid, or (iii) the filling liquid and the coating liquid A method of manufacturing a secondary battery according to any one of claims 1 to 10 by injecting an electrolyte after the injection between the assembly and the battery case.

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