Title of Invention: Lithium-free battery, and manufacturing method thereof
technical field
[One]
Cross-Citation with Related Application(s)
[2]
This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0055157 dated May 08, 2020 and Korean Patent Application No. 10-2021-0008511 dated January 21, 2021, and All content disclosed in the literature is incorporated as a part of this specification.
[3]
The present invention relates to a lithium-free battery and a method for manufacturing the same.
background
[4]
Due to the rapid increase in the use of fossil fuels, the demand for the use of alternative energy or clean energy is increasing.
[5]
Currently, a secondary battery is a typical example of an electrochemical device using such electrochemical energy, and its use area is gradually expanding.
[6]
In recent years, as technology development and demand for portable devices such as portable computers, portable phones, and cameras increase, the demand for secondary batteries as an energy source is rapidly increasing. A lot of research has been done on an eco-friendly lithium secondary battery, and it is also commercialized and widely used.
[7]
In general, a lithium secondary battery has a structure in which a non-aqueous electrolyte is impregnated in an electrode assembly comprising a positive electrode, a negative electrode, and a porous separator. In addition, in general, the positive electrode is generally manufactured by coating a positive electrode mixture including a positive electrode active material on aluminum foil, and the negative electrode is manufactured by coating a negative electrode mixture containing a negative electrode active material on a copper foil.
[8]
Usually, the positive active material is lithium transition metal oxide, and the negative active material is a carbon-based material.
[9]
However, recently, as a negative electrode active material, a lithium metal battery using lithium metal itself has been commercialized, and further, when manufacturing an electrode, only a current collector is used as the negative electrode, lithium is supplied from the positive electrode by charging, and lithium metal is used as the negative electrode active material. Research on lithium-free batteries to be used is also being actively conducted. A lithium-free battery is considered as a battery concept that can achieve the highest energy density in terms of high energy density.
[10]
However, in the negative electrode, a lithium plate layer is formed by electro-deposition due to charging on the current collector. At this time, a lithium plate layer with a low electrodeposition density is formed on the current collector, and the electrolyte side reaction is severe, resulting in a fast lifespan characteristic. degeneration occurs.
[11]
Therefore, it is necessary to develop a lithium-free battery having an increased electrodeposition density of the lithium plate layer by solving this problem.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[12]
An object of the present invention is to solve the problems of the prior art as described above and the technical problems that have been requested from the past.
[13]
Specifically, it is an object of the present invention to provide a lithium-free battery in which a lithium plate layer having a high electrodeposition density can be formed on an anode by a simpler method.
[14]
In addition, according to this, it is an object of the lithium-free battery to prevent a side reaction of the electrolyte to improve the lifespan characteristics.
means of solving the problem
[15]
According to one embodiment of the present invention for achieving this object, as a lithium-free battery comprising a positive electrode, a negative electrode, a separator, and a lithium non-aqueous electrolyte, the negative electrode is, Mg, Ca, Al, Si, Ge, Sn, a metal substrate including at least one metal selected from the group consisting of Pb, As, Sb, Bi, Ag, Zn, Cd, P and Hg; a lithium-metal alloy layer formed on the metal substrate; and a lithium plate layer formed on the lithium-metal alloy layer, wherein the metal included in the lithium-metal alloy layer is a metal included in the metal substrate.
[16]
The lithium-metal alloy layer and the lithium plate layer may be formed by charging the lithium-free battery.
[17]
In this case, the capacity per unit area of ​​the positive electrode (mAh/cm 2 ) may be greater than the capacity per unit area of ​​the negative electrode.
[18]
The metal substrate may include one or more metals selected from the group consisting of Si, Ge, Sn, Sb, Mg, Bi, As, Pb, P, and Zn.
[19]
The metal substrate may have a thickness of 3 μm to 100 μm.
[20]
The metal substrate may have a thickness of 10 μm to 80 μm.
[21]
The lithium-metal alloy layer and the lithium plate layer may each have a thickness of at least 0.1 μm or more.
[22]
According to another embodiment of the present invention, there is provided a method for manufacturing a lithium-free battery, comprising the steps of: (a) forming a positive electrode mixture layer on at least one surface of a positive electrode current collector to manufacture a positive electrode; (b) Mg, Ca, Al, Si, Ge, Sn, Pb, As, Sb, Bi, Ag, Zn, Cd, consisting of a metal substrate containing at least one metal selected from the group consisting of P and Hg preparing a preliminary negative electrode; (c) disposing a separator between the positive electrode and the preliminary negative electrode to prepare an electrode assembly; (d) embedding the electrode assembly and the lithium non-aqueous electrolyte in a battery case, sealing, and then charging the lithium-free battery, wherein the capacity per unit area of ​​the positive electrode is greater than the capacity per unit area of ​​the negative electrode A manufacturing method is provided.
[23]
The metal substrate may include one or more metals selected from the group consisting of Si, Ge, Sn, Sb, Mg, Bi, As, Pb, P, and Zn.
[24]
The metal substrate may have a thickness of 3 μm to 100 μm.
Modes for carrying out the invention
[25]
Hereinafter, the present invention will be described in more detail to help the understanding of the present invention.
[26]
The terms or words used in the present specification and claims are not to be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. It should be interpreted as meaning and concept consistent with the technical idea of ​​the present invention based on the principle that there is.
[27]
The terminology used herein is used to describe exemplary embodiments only, and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise.
[28]
In addition, throughout the specification, when a part "includes" a certain component, this means that other components may be further included, rather than excluding other components, unless otherwise stated.
[29]
[30]
According to an embodiment of the present invention, a lithium-free battery comprising a positive electrode, a negative electrode, a separator, and a lithium non-aqueous electrolyte, wherein the negative electrode is, Mg, Ca, Al, Si, Ge, Sn, Pb, As, Sb, a metal substrate comprising at least one metal selected from the group consisting of Bi, Ag, Zn, Cd, P and Hg; a lithium-metal alloy layer formed on the metal substrate; and a lithium plate layer formed on the lithium-metal alloy layer, wherein the metal included in the lithium-metal alloy layer is a metal included in the metal substrate. In this case, the metal substrate may be made of one or more metals selected from the group consisting of Mg, Ca, Al, Si, Ge, Sn, Pb, As, Sb, Bi, Ag, Zn, Cd, P, and Hg. .
[31]
In such a lithium-free battery, it is ultimately important to increase the electrodeposition density of the lithium plate layer. When the electrodeposition density is increased, the specific surface area is reduced, and thus, the electrolytic solution side reaction is minimized, thereby improving the lifespan characteristics of the lithium-free battery.
[32]
Specifically, in the negative electrode of the present application, a preliminary negative electrode is prepared using the metal substrate, a lithium-free battery is prepared using the negative electrode, and a lithium-metal alloy layer and a lithium plate layer are formed on the metal substrate through charging. form, and it is used as a cathode. Accordingly, the lithium-metal alloy layer and the lithium plate layer may be formed by charging the lithium-free battery.
[33]
When a battery is manufactured using a preliminary negative electrode made of a metal substrate and charging is performed, Li ions transferred from the positive electrode through the lithium non-aqueous electrolyte chemically react with the metal substrate to form a lithium-metal alloy layer on the metal substrate do.
[34]
Accordingly, the metal substrate should be a metal substrate capable of forming an alloy with lithium, and the above materials may be used.
[35]
On the other hand, the higher the tendency to alloy with lithium, and more specifically, the higher the volume energy density of a metal, the more the alloy layer is formed by reacting with lithium relative to the same volume. can increase
[36]
Accordingly, it is more preferable to be formed of a material that forms more lithium alloy layers due to higher bulk energy density among the metal substrates. Specifically, the metal substrates are Si, Ge, Sn, Sb, Mg, Bi. , As, Pb, P, and may be made of one or more metals selected from the group consisting of Zn. In this case, the metal substrate may be made of one or more metals selected from the group consisting of Si, Ge, Sn, Sb, Mg, Bi, As, Pb, P, and Zn. Such a metal may correspond to a material having a better lithium alloy tendency than Al, that is, a high bulk energy density.
[37]
On the other hand, since the reaction area of ​​the metal substrate is fixed, when charging is performed, a lithium-metal alloy layer is formed up to a predetermined portion, and the capacity per unit area of ​​the positive electrode (mAh/cm 2 ) is larger than the capacity per unit area of ​​the negative electrode, If charging is continued, lithium-metal alloying does not proceed any further, and a lithium plate layer is formed on the lithium-metal alloy layer, and lithium on this lithium-metal alloy layer and lithium in the lithium plate layer are used as an anode. used as an active material.
[38]
That is, the negative electrode uses lithium as an active material to manufacture a battery using a metal substrate and then to receive it by charging. It is essential to form even a plate layer, and it is possible by increasing the amount of lithium used as the negative electrode active material.
[39]
On the other hand, in the prior art, the electrodeposition density of the lithium plate layer is low, so there is a problem such as a side reaction of the electrolyte solution, so there is a big limitation in its use. It is possible to increase the electrodeposition density of the plate layer. Therefore, in the present invention, the capacity per unit area (mAh/cm 2 ) of the positive electrode can be configured to be larger than the capacity per unit area of ​​the negative electrode, thereby improving the overall capacity of the lithium-free battery and increasing the electrodeposition density of the lithium plate layer Lifespan characteristics can also be improved.
[40]
Here, the capacity per unit area of ​​the positive electrode can be obtained by multiplying the actual expressed capacity (mAh/g) of the positive electrode active material by the amount (g) of the active material, and dividing it by the area (cm 2 ) of the current collector.
[41]
In addition, the capacity per unit area of ​​the negative electrode means the capacity expressed while lithium and metal are alloyed. The capacity per unit area of ​​the negative electrode may be calculated based on the amount of the lithium-metal alloy layer that may be formed on the metal substrate.
[42]
The metal substrate may be made of metals as described above, and the term 'consisting of' means containing 100% of these metals, or 5% by weight or less, 3% by weight or less as an unavoidable impurity, and further It may contain up to a range containing other metals and oxides in an amount of 1 wt% or less.
[43]
The metal substrate may have a thickness of 3 μm to 100 μm, and specifically, may have a thickness of 10 μm or more and 80 μm or less, or 10 μm or more and 60 μm or less. More specifically, it may have a thickness of 30 μm or more and 60 μm or less.
[44]
Out of the above range, if the thickness is too thin, the thickness becomes too thin due to the alloying reaction with lithium, resulting in a problem of a decrease in strength, and as the lithium-metal alloy layer is formed very thin and a lot of lithium plate layers are formed, the lithium plate Since the specific surface area of ​​the layer is increased, a lot of side reactions of the electrolyte solution occur, and the effect of the present invention cannot be achieved. Conversely, when it is too thick, the overall volume increases, and the volumetric energy density decreases, which is not preferable in terms of capacity.
[45]
On the other hand, the negative electrode in the lithium-free battery according to the present invention essentially includes a lithium-metal alloy layer and a lithium plate layer, and the thickness thereof is not particularly limited, but each layer may have a thickness of at least 0.1 μm or more. And, specifically, it may have a thickness of 1 μm or more, more specifically, 3 μm or more.
[46]
This is also related to the thickness of the metal substrate and is also due to the difference in capacity per unit area between the positive electrode and the negative electrode. Accordingly, the thickness of each of the lithium-metal alloy layer and the lithium plate layer may vary depending on how the battery is configured. In addition, the thickness is also affected by the thickness of the metal substrate. Out of the above range, when the thickness of the lithium-metal alloy layer is too thin, the lithium plating layer, which is vulnerable to reaction with the electrolyte, becomes too thick, and many by-products are formed, which is not preferable because the internal resistance of the cell rapidly increases.
[47]
In addition, when the lithium plate layer is too thin, the lithium-metal alloy layer becomes too thick and the lithium-metal alloy layer and the metal substrate collapse when the alloy is lost during discharging, and when charging again, the lithium-metal alloy on the metal substrate Since this does not occur entirely, the lithium plate layer is irregularly formed, and it is difficult to increase the electrodeposition density, so life deterioration may be accelerated, which is undesirable. Of course, in this case, the capacity of the battery is also small, so it is difficult to maximize the energy density even though the lithium-free battery is an advantage.
[48]
Meanwhile, according to another embodiment of the present invention, there is provided a method for manufacturing the lithium-free battery, comprising the steps of: (a) forming a positive electrode mixture layer on at least one surface of a positive electrode current collector to manufacture a positive electrode; (b) Mg, Ca, Al, Si, Ge, Sn, Pb, As, Sb, Bi, Ag, Zn, Cd, consisting of a metal substrate containing at least one metal selected from the group consisting of P and Hg preparing a preliminary negative electrode; (c) disposing a separator between the positive electrode and the preliminary negative electrode to prepare an electrode assembly; (d) embedding the electrode assembly and the lithium non-aqueous electrolyte in a battery case, sealing, and then charging the lithium-free battery, wherein the capacity per unit area of ​​the positive electrode is greater than the capacity per unit area of ​​the negative electrode A manufacturing method is provided. In this case, the metal substrate may be made of one or more metals selected from the group consisting of Mg, Ca, Al, Si, Ge, Sn, Pb, As, Sb, Bi, Ag, Zn, Cd, P, and Hg. .
[49]
Here, as described above, in detail, the metal substrate may include one or more metals selected from the group consisting of Si, Ge, Sn, Sb, Mg, Bi, As, Pb, P and Zn, and , may have a thickness of 3 μm to 100 μm. Here, the metal substrate may be made of one or more metals selected from the group consisting of Si, Ge, Sn, Sb, Mg, Bi, As, Pb, P, and Zn.
[50]
Other specific details are the same as described above.
[51]
That is, the lithium-free battery according to the present invention uses a metal substrate as a preliminary negative electrode, uses it to manufacture an electrode assembly, and then seals it in a battery case together with a lithium non-aqueous electrolyte and performs charging. A lithium-metal alloy layer and a lithium plate layer are formed on the metal substrate. In addition, as described above, in order to have such a structure, the capacity per unit area of ​​the positive electrode may be greater than the capacity per unit area of ​​the negative electrode.
[52]
Meanwhile, other components of the lithium-free battery will be described.
[53]
As described above, the positive electrode is manufactured by forming a positive electrode mixture layer on at least one surface of the positive electrode current collector. Here, the positive electrode mixture layer includes a positive electrode active material, a binder, and a conductive material, and may optionally further include a filler.
[54]
The positive electrode current collector is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or carbon, nickel, Those surface-treated with titanium, silver, etc. can be used. In addition, the positive electrode current collector may typically have a thickness of 3 to 500 μm, and may increase the adhesion of the positive electrode active material by forming fine irregularities on the surface of the current collector. For example, it may be used in various forms, such as a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven body.
[55]
The positive active material as the active material may include, for example, a layered compound such as lithium nickel oxide (LiNiO 2 ) or a compound substituted with one or more transition metals; Lithium manganese oxides such as Formula Li 1+x Mn 2-x O 4 (where x is 0 to 0.33), LiMnO 3 , LiMn 2 O 3 , and LiMnO 2 ; lithium copper oxide (Li 2 CuO 2 ); LiV 3 O 8 , LiV 3 O 4 , V 2 O 5 , Cu 2 V 2 O 7vanadium oxides such as; Ni site-type lithium nickel oxide represented by the formula LiNi 1-x M x O 2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3); Formula LiMn 2-x M x O 2 (where M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li 2 Mn 3 MO 8 (where M = Fe, Co, lithium manganese composite oxide represented by Ni, Cu or Zn; LiMn 2 O 4 in which a part of Li in the formula is substituted with an alkaline earth metal ion ; disulfide compounds; Fe 2 (MoO 4 ) 3 It may be composed of, and the like, and is not limited thereto, and materials known in the art may be used.
[56]
The binder is a component that assists in bonding of the active material and the conductive material and bonding to the current collector, and is typically 0.1 to 30% by weight, specifically 1 to 10% by weight, more specifically, based on the total weight of the positive electrode mixture layer. is added in an amount of 1 to 5% by weight. Examples of such binders include polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl alcohol. pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene ter polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, various copolymers, and the like.
[57]
The conductive material is typically added in an amount of 0.1 to 30% by weight, specifically 1 to 10% by weight, and more specifically 1 to 5% by weight based on the total weight of the positive electrode mixture layer. Such a conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery. For example, graphite such as natural graphite or artificial graphite; carbon black, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; A conductive material such as a polyphenylene derivative may be used.
[58]
The filler is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery, and for example, an olipine-based polymer such as polyethylene or polypropylene; A fibrous material such as glass fiber or carbon fiber is used.
[59]
As the separation membrane, an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 μm, and the thickness is generally 5 to 300 μm. As such a separation membrane, For example, olefin polymers, such as chemical-resistance and hydrophobic polypropylene; A sheet or nonwoven fabric made of glass fiber or polyethylene is used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.
[60]
The lithium non-aqueous electrolyte generally includes a lithium salt and a non-aqueous solvent. The non-aqueous solvent includes, but is not limited to, a non-aqueous organic solvent, an organic solid electrolyte, an inorganic solid electrolyte, and the like.
[61]
Examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyl lactone, 1,2-dimethoxy ethane, tetrahydroxy furan (furan), 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane , acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbo An aprotic organic solvent such as a nate derivative, a tetrahydrofuran derivative, ether, methyl pyropionate, or ethyl propionate can be used.
[62]
Examples of the organic solid electrolyte include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphoric acid ester polymers, poly agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, A polymer containing an ionic dissociation group or the like can be used.
[63]
Examples of the inorganic solid electrolyte include Li 3 N, LiI, Li 5 NI 2 , Li 3 N-LiI-LiOH, LiSiO 4 , LiSiO 4 -LiI-LiOH, Li 2 SiS 3 , Li 4 SiO 4 , Nitrides , halides, sulfates, etc. of Li such as Li 4 SiO 4 -LiI-LiOH, Li 3 PO 4 -Li 2 S-SiS 2 and the like may be used.
[64]
The lithium salt is a material readily soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiAlCl 4 , CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2 ) 2NLi, lithium chloroborane, lithium lower aliphatic carboxylate, lithium tetraphenyl borate, imide-based salt and the like can be used.
[65]
In addition, lithium non-aqueous electrolytes, for the purpose of improving charge and discharge characteristics, flame retardancy, etc., for example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme (glyme), hexaphosphate tri Amide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. are added. it might be In some cases, in order to impart incombustibility, a halogen-containing solvent such as carbon tetrachloride and ethylene trifluoride may be further included, and carbon dioxide gas may be further included to improve high-temperature storage characteristics, and FEC (Fluoro-Ethylene) Carbonate), PRS (propene sultone), etc. may be further included.
[66]
The battery case is not limited as long as it has a structure capable of embedding an electrode assembly, and may be a pouch-type battery case known in the art, or a prismatic or cylindrical battery case made of a metal can.
[67]
The filling may be full filling, and then aging treatment is performed at high temperature and/or room temperature. Thus, a lithium-metal alloy layer and a lithium plate layer are formed on the metal substrate of the preliminary negative electrode.
[68]
[69]
Hereinafter, preferred examples of the present invention, comparative examples, and experimental examples for evaluating them are described. However, it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of the present description only by illustrating the present description, and it is natural that such modifications and modifications belong to the appended claims. will be.
[70]
[71]

[72]
Lithium transition metal oxide (LiNi 1/3 Co 1/3 Mn 1/3 O 2 ) was used as a positive electrode active material, PVdF as a binder and Super-P as a conductive material, and a weight ratio of positive electrode active material: binder: conductive material Rho 96: 2: 2, the active material slurry added to NMP was coated on Al foil at 4 mAh/cm 2 per side , dried in a dryer at 130° C. under an air atmosphere, and then rolled to prepare a positive electrode.
[73]
A Si foil having a thickness of 30 μm, a length of 40 mm, and a width of 60 mm was used as a preliminary negative electrode.
[74]
An SRS separator having a thickness of 20 μm was assembled on the positive electrode and the preliminary negative electrode using a stacking method, and the assembled battery was embedded in an aluminum pouch-type battery case, and 1M LiFSI was dissolved in a volume ratio of 3:7 fluoroethylene After injecting carbonate (FEC) and ethylmethyl carbonate (EMC) solutions, the battery case was sealed to prepare a monocell.
[75]
[76]

[77]
A lithium-free battery was prepared in the same manner as in Example 1, except that a Si foil having a thickness of 60 μm was used as a preliminary negative electrode in Example 1.
[78]
[79]

[80]
A lithium-free battery was prepared in the same manner as in Example 1, except that Sn foil having a thickness of 30 μm was used as a preliminary negative electrode in Example 1.
[81]
[82]

[83]
A lithium-free battery was prepared in the same manner as in Example 1, except that in Example 1, an Al foil having a thickness of 30 μm was used as a preliminary negative electrode.
[84]
[85]

[86]
A lithium-free battery was prepared in the same manner as in Example 1, except that a Cu foil having a thickness of 30 μm was used as a preliminary negative electrode in Example 1.
[87]
[88]

[89]
A lithium-free battery was prepared in the same manner as in Example 1, except that in Example 1, a foil containing 10 wt% of Si as a dopant in a Cu matrix having a thickness of 30 μm was used as a preliminary negative electrode.
[90]
[91]

[92]
A lithium-free battery was prepared in the same manner as in Example 1, except that in Example 1, Sn was plated to a thickness of 1 μm by electroless plating on a Ni foil having a thickness of 30 μm as a preliminary negative electrode.
[93]
[94]

[95]
The loading amounts of the positive and negative electrodes used in Examples 1 to 4 and Comparative Examples 1 to 3 were measured as follows.
[96]
The positive electrode loading amount was measured by coin punching the positive electrode manufactured in Example with 1.6 cm 2 and charging and discharging at a rate of 0.1C using a Li metal electrode as the counter electrode to measure the discharge capacity. The anode loading can be calculated by dividing the anode area by the measured discharge capacity.
[97]
The negative electrode loading amount was measured by coin punching the negative electrode produced in each Example and Comparative Example with 1.6 cm 2 and charging and discharging at a rate of 0.1C using a Li metal electrode as the counter electrode until lithium-metal alloying was performed. Measure the discharge capacity. By dividing the area of ​​the anode by the measured discharge capacity, the cathode loading can be calculated.
[98]
Table 1 shows the calculated positive electrode loading and negative electrode loading.
[99]
[Table 1]
Capacity per unit area of ​​anode (mAh/cm 2 ) Capacity per unit area of ​​anode (mAh/cm 2 )
Example 1 4.01 2.21
Example 2 2.41
Example 3 1.53
Example 4 0.91
Comparative Example 1 0
Comparative Example 2 0.35
Comparative Example 3 0.15
[100]
Referring to Table 1, it can be seen that the capacity per unit area of ​​the positive electrode is greater than the capacity per unit area of ​​the negative electrode. In a lithium-free battery manufactured by applying such a positive electrode and a negative electrode, charging is performed according to the capacity per unit area of ​​the positive electrode, a lithium-metal alloy layer is formed on the metal substrate by the capacity per unit area of ​​the negative electrode, and the remaining capacity is a lithium plate layer. can be known In addition, in the case of copper, it can be seen that alloying with lithium is not made.
[101]
[102]

[103]
After charging the lithium-free batteries prepared in Examples 1 to 4 and Comparative Examples 1 to 3 under the following conditions, the lithium-free battery was disassembled to obtain the thickness and electrodeposition density of the lithium plate layer formed on the negative electrode, and are shown in Table 2 below. indicated.
[104]
Charge: 0.2C, CC/CV, 4.25V, 1/20C cut-off
[105]
The thickness of the lithium plate layer was determined by selecting two arbitrary points and the average of the thicknesses was obtained, and the electrodeposition density of the lithium plate layer was quantified by calculating the precipitation mass and precipitation volume.
[106]
[Table 2]
Plate layer thickness (um) Deposition Density (g/cc)
Example 1 35 0.30
Example 2 30 0.33
Example 3 45 0.22
Example 4 60 0.17
Comparative Example 1 100 0.10
Comparative Example 2 77 0.13
Comparative Example 3 85 0.12
[107]
(Theoretical density of lithium metal: 0.54 g/cm 3 ) Referring to Table 2, when the metal according to Examples 1 to 4 of the present application is used, the thickness of the lithium plate layer is thin and the density is improved. It can be seen that it is densely formed. On the other hand, in Comparative Example 1 using Cu, there is almost no improvement in the electrodeposition density, and when the metal defined herein as a dopant is included (Comparative Example 2), or is formed in a very thin range (Comparative Example 3), sufficient electrodeposition density is It was confirmed that the improvement result could not be obtained. From this, in order to sufficiently increase the electrodeposition density of the lithium plate layer to improve battery performance, a sufficient amount of lithium and an alloyable metal are required, and the metal is formed as a whole to improve the electrodeposition density of the lithium plate layer over the entire area. can know that
[108]
On the other hand, Example 4 using Al has a predetermined electrodeposition density improvement effect, but the improvement effect is insignificant compared to Si or Sn of Examples 1 to 3.
[109]
[110]

[111]
The lithium-free batteries of Examples 1 to 4 and Comparative Examples 1 to 3 were charged and discharged at 0.2 C to measure the one-time discharge capacity, and after charging and discharging additionally under the following conditions, 100 times compared to the one-time discharge capacity The discharge capacity retention rate was calculated and the results are shown in Table 3 below.
[112]
Charge: 0.2C, CC/CV, 4.25V, 1/20C cut-off
[113]
Discharge: 0.5C, CC, 3.0V, cut-off
[114]
[Table 3]
One-time capacity (mAh) 100 times capacity retention rate (%)
Example 1 61.9 97
Example 2 62.3 99
Example 3 61.5 93
Example 4 61.3 90
Comparative Example 1 60.9 50
Comparative Example 2 61.0 65
Comparative Example 3 61.2 60
[115]
Referring to Table 3, in the case of Examples 1 to 4 according to the present invention, compared with Comparative Examples 1 to 3 having a difference in metal type or composition, it can be confirmed that the density of the lithium plate layer is increased and the lifespan characteristics are excellent. In particular, it was confirmed that Example 2, in which the thickness of the metal substrate was thick, exhibited the best life characteristics. In addition, examining Examples 1 to 4, it can be seen that a material having a higher theoretical capacity to be alloyed with lithium such as Si or Sn among metal substrates is advantageous for lifespan.
[116]
[117]
Those of ordinary skill in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above contents.
Industrial Applicability
[118]
As described above, the lithium-free battery according to an embodiment of the present invention uses a metal capable of alloying with lithium as a metal substrate, thereby forming a lithium-metal alloy layer by charging on the metal substrate, Forming a lithium plate layer on the lithium-metal alloy layer has an effect of increasing the electrodeposition density of the lithium plate layer, thereby minimizing side reactions with the electrolyte to improve lifespan characteristics.
Claims
[Claim 1]
A lithium-free battery comprising a positive electrode, a negative electrode, a separator, and a lithium non-aqueous electrolyte, wherein the negative electrode is Mg, Ca, Al, Si, Ge, Sn, Pb, As, Sb, Bi, Ag, Zn, Cd, P and a metal substrate comprising at least one metal selected from the group consisting of Hg; a lithium-metal alloy layer formed on the metal substrate; and a lithium plate layer formed on the lithium-metal alloy layer, wherein the metal included in the lithium-metal alloy layer is a metal included in the metal substrate.
[Claim 2]
The lithium-free battery according to claim 1, wherein the lithium-metal alloy layer and the lithium plate layer are formed by charging the lithium-free battery.
[Claim 3]
The lithium-free battery according to claim 2, wherein the capacity per unit area of ​​the positive electrode (mAh/cm 2 ) is greater than the capacity per unit area of ​​the negative electrode.
[Claim 4]
The lithium-free battery of claim 1 , wherein the metal substrate comprises at least one metal selected from the group consisting of Si, Ge, Sn, Sb, Mg, Bi, As, Pb, P, and Zn.
[Claim 5]
The lithium-free battery of claim 1 , wherein the metal substrate has a thickness of 3 μm to 100 μm.
[Claim 6]
The lithium-free battery according to claim 5, wherein the metal substrate has a thickness of 10 μm to 80 μm.
[Claim 7]
The lithium-free battery of claim 1 , wherein the lithium-metal alloy layer and the lithium plate layer each have a thickness of 0.1 μm or more.
[Claim 8]
A method for manufacturing a lithium-free battery according to claim 1, comprising the steps of: (a) forming a positive electrode mixture layer on at least one surface of a positive electrode current collector to prepare a positive electrode; (b) Mg, Ca, Al, Si, Ge, Sn, Pb, As, Sb, Bi, Ag, Zn, Cd, consisting of a metal substrate containing at least one metal selected from the group consisting of P and Hg preparing a preliminary negative electrode; (c) disposing a separator between the positive electrode and the preliminary negative electrode to prepare an electrode assembly; (d) embedding the electrode assembly and the lithium non-aqueous electrolyte in a battery case, sealing, and then charging; Including, wherein the capacity per unit area of ​​the positive electrode is greater than the capacity per unit area of ​​the negative electrode.
[Claim 9]
The method of claim 8, wherein the metal substrate comprises at least one metal selected from the group consisting of Si, Ge, Sn, Sb, Mg, Bi, As, Pb, P, and Zn.
[Claim 10]
The method of claim 8 , wherein the metal substrate has a thickness of 3 μm to 100 μm.