Therefore, the problem to be solved by the present invention is to use a protective layer containing a polymer having a sulfur chain group as a protective layer of a lithium metal negative electrode to form a chemically stable sulfide-based interface on the surface of the lithium metal negative electrode. It is to provide a lithium metal secondary battery having a self-healing function that prevents rapid growth of lithium dendrites at a location and a battery module including the same.
[10]
Task resolution
[11]
The present invention has been derived to solve the above technical problem. The first aspect of the present invention relates to a lithium metal secondary battery, wherein the lithium metal secondary battery includes an electrode assembly including an anode, a cathode, and a separator interposed between the anode and the cathode; And a non-aqueous electrolyte solution impregnating the electrode assembly, the negative electrode including lithium metal, the secondary battery further comprising a protective layer interposed between the negative electrode and the separator, and the protective layer, It contains a polymer having a sulfur chain group.
[12]
The second aspect of the present invention, in the first aspect, the polymer having a sulfur chain group, a polymer having a sulfate group (SO 4 2- ) and lithium polysulfide (Li 2 S n , 0< n <10) It is the result of the nucleophilic substitution reaction.
[13]
The third aspect of the present invention, in the second aspect, the polymer having the sulfate group (SO 4 2- ) is to include a carrageenan (carrageenan) polymer.
[14]
In a fourth aspect of the present invention, in the third aspect, the carrageenan polymer includes λ-carrageenan.
[15]
In the fifth aspect of the present invention, in at least one of the first to fourth aspects, the protective layer includes a porous polymer layer or a porous mixed layer in which inorganic materials are mixed as a protective layer substrate, and the protective layer substrate contains sulfur A polymer having a chain group is introduced.
[16]
In the sixth aspect of the present invention, in at least one of the first to fifth aspects, the non-aqueous electrolyte solution further comprises LiNO 3 as an additive.
[17]
In the seventh aspect of the present invention, in at least one of the first to sixth aspects, the thickness of the protective layer is 0.1 μm to 100 μm.
[18]
In the eighth aspect of the present invention, in at least one of the first to seventh aspects, the protective layer comprises a protective layer substrate, the protective layer substrate is a polyvinylidene-based polymer comprising a vinylidene polymerization unit It contains resin.
[19]
In the ninth aspect of the present invention, in at least one of the first to eighth aspects, the protective layer further includes inorganic particles, and the inorganic particles include BaTiO 3 , SrTiO 3 , SnO 2 , CeO 2 , MgO , NiO, CaO, ZnO, ZrO 2 , Y 2 O 3 , Al 2 O 3 , TiO 2 , SiC, or two or more of these.
[20]
In the tenth aspect of the present invention, in at least one of the first to ninth aspects, the protective layer has a porosity of 5 vol% to 95 vol%.
[21]
Effects of the Invention
[22]
According to the present invention, as a protective layer of a lithium metal negative electrode, by including a polymer having a sulfur chain group, a chemically stable sulfide-based interface can be formed on the surface of the lithium metal negative electrode, thereby preventing rapid growth of lithium dendrites. It can, and ultimately, improve the safety of the battery.
[23]
Such a sulfur chain group prevents the reaction from being excessively concentrated at a specific location by causing a reduction reaction instead of lithium metal, and acts as a self-healing agent to prevent the deterioration of the protective layer.
[24]
Furthermore, these sulfur chain groups are fixed to the polymer and then only a predetermined amount necessary for the reaction is cut off and continuously participates in the reaction.
[25]
Brief description of the drawing
[26]
The following drawings attached to the present specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of ​​the present invention together with the contents of the above-described invention, so the present invention is limited to those described in those drawings. It should not be construed as limited.
[27]
1 is a view showing the color change of the lithium polysulfide solution and reactivity with the λ-carrageenan polymer through UV-VIS analysis.
[28]
2 is an XPS analysis graph before and after the reaction of the lithium polysulfide solution and the λ-carrageenan polymer.
[29]
3 is a graph showing a comparison of the number of cycles until a short circuit by dendrites occurs after driving the cells manufactured in Comparative Examples and Examples.
[30]
4 is a graph showing comparison of ionic conductivity of the protective layer prepared in Comparative Examples and Examples.
[31]
Mode for carrying out the invention
[32]
Hereinafter, the present invention will be described in detail. The terms or words used in the specification and claims should not be interpreted as being limited to ordinary or dictionary meanings, and the inventor can appropriately define the concept of terms in order to best describe his or her invention in the best way. Based on the principle of being present, it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention.
[33]
Accordingly, the embodiments described in the embodiments and the drawings described in this specification are only one of the most preferred embodiments of the present invention, and do not represent all of the technical spirit of the present invention. It should be understood that there may be equivalents and variations.
[34]
According to an aspect of the present invention, an electrode assembly including a positive electrode, a lithium metal negative electrode and a separator interposed between the positive electrode and the lithium metal negative electrode; And a non-aqueous electrolyte solution impregnating the electrode assembly, further comprising a protective layer interposed between the lithium metal negative electrode and the separator, wherein the protective layer includes a polymer having a sulfur chain group. It is characterized by.
[35]
The polymer having a sulfur chain group of the present application can form a chemically stable sulfide-based interface on the surface of the lithium metal negative electrode, thereby preventing rapid lithium dendrite growth and ultimately improving battery safety. have.
[36]
In addition, the sulfur chain group prevents the reaction from being excessively concentrated at a specific location by causing a reduction reaction instead of lithium metal, and acts as a self-healing agent to prevent the deterioration of the protective layer.
[37]
Furthermore, these sulfur chain groups are fixed to the polymer of the protective layer, and then only a predetermined amount required for the reaction is cut off, and continuously participates in the reaction.
[38]
Here, the polymer having a sulfur chain group may be a product of a nucleophilic substitution reaction between a polymer having a sulfate group (SO 4 2- ) and lithium polysulfide (Li 2 S n ). In one embodiment of the present invention, n may have a value of 0