KR102176091B1 - Liquid electrolyte for lithium secondary battery and lithium manganese oxide symmetric battery system comprising the same - Google Patents

Abstract

The present invention relates to a liquid electrolyte for a lithium secondary battery having high capacity and high service life properties, and to a lithium manganese oxide symmetric battery system comprising the liquid electrolyte. The liquid electrolyte for a lithium secondary battery according to an embodiment of the present invention comprises high concentration of a sulfonylimide compound.

Description

Liquid electrolyte for lithium secondary battery and lithium manganese oxide symmetric battery system including the same TECHNICAL FIELD {LIQUID ELECTROLYTE FOR LITHIUM SECONDARY BATTERY AND LITHIUM MANGANESE OXIDE SYMMETRIC BATTERY SYSTEM COMPRISING THE SAME}

The present invention relates to a liquid electrolyte for a lithium secondary battery and a lithium manganese oxide symmetric battery system including the same.

Lithium secondary batteries are an element corresponding to the heart of the digital age, which is rapidly applied to mobile phones and notebook computers with high electromotive force and high energy density.

In general, a carbon material is mainly used as a negative electrode active material in such a lithium secondary battery, and the use of lithium metal and sulfur compounds is also considered. In addition, lithium-containing cobalt oxide (LiCoO ₂ ) is mainly used as the positive electrode active material.In addition, lithium-containing manganese oxides such as LiMnO _{2 in a} layered crystal structure and LiMn ₂ O _{4 in a} spinel crystal structure, and lithium-containing nickel oxide (LiNiO The use of ₂ ) is also being considered. In addition, as an electrolyte, a non-aqueous organic solution of a lithium salt, which is difficult to electrolyze, is used as the electrolyte because the anode material has a potential of 3 V to 4 V compared to lithium metal and the negative electrode is also less than 1 V compared to lithium metal .

However, when a battery is manufactured using the non-aqueous organic electrolyte, the manufacturing cost is high because the manufacturing process must be performed in a dry space without moisture. In addition, a porous membrane (separator) separating the electrode is also an expensive material. In terms of performance, organic electrolytes have very low ionic conductivity. In addition, the non-aqueous organic electrolyte has been pointed out as a disadvantage in terms of safety in that there is a risk of ignition or explosion due to ignition or side reactions.

In the case of power sources for electric vehicles, output and safety are required, but lithium secondary batteries that do not use organic electrolytes are difficult to satisfy these requirements, so most of the power supplies for electric vehicles currently in practical use are nickel hydride batteries using aqueous electrolytes. (Ni-metal hydride). However, in the case of a nickel hydride battery, since the output is low and the capacity is very low compared to the lithium secondary battery, research on an aqueous electrolyte lithium secondary battery that can be economically advantageous in terms of process while excluding the risk is recently being conducted.

In an aqueous lithium secondary battery, a material capable of inserting/detaching an intercalated paper, which is one of an alkali or alkaline earth metal, is used as the positive electrode and negative electrode active material, and the electrolyte is an aqueous electrolyte in which the intercalated species are dissolved. The capacity of the aqueous lithium secondary battery represents several tens of mAh/g. In the case of a lithium secondary battery using an aqueous electrolyte, it is advantageous in terms of high ionic conductivity and safety of the aqueous electrolyte, and the process and manufacturing cost are also low. In addition, in general, a battery using an aqueous electrolyte solution is advantageous in terms of environment than an organic electrolyte solution. However, the difference in the chemical potential of lithium in the anode/cathode electrode is indicated by the electromotive force.In the case of an aqueous electrolyte, since it is a reaction within a stable potential range in which decomposition of water does not occur, the energy density is low because it is 1 V-2 V, which is lower than that of the organic electrolyte The initial efficiency, reversibility, or life characteristics of the negative electrode active material having a relatively low potential are problematic.

On the other hand, lithium manganese oxides such as LiMnO ₂ and LiMn ₂ O ₄ as a positive electrode active material have advantages in that they are excellent in thermal safety and inexpensive, but there are problems in that capacity is small, cycle characteristics are poor, and high temperature characteristics are poor. In the case of spinel-based LiMn ₂ O ₄ , a relatively flat potential is shown in the 4 V region (3.7 V to 4.3 V) and the 3 V region (2.7 V to 3.1 V), but the cycle and storage characteristics are very poor in the 3 V region, It is known to be difficult to use. When using the 3 V region of spinel lithium manganese oxide, the actual capacity is generally lower than the theoretical capacity, and the C-rate characteristic is also lower.

Therefore, the study on the utilization of the 3 V region of spinel lithium manganese oxide is known to be very difficult to solve, and thus the situation is poor compared to the study on the utilization of the 4 V region.

The present invention is to solve the above-described problems, and an object of the present invention is to provide a liquid electrolyte for a lithium secondary battery having high capacity and high lifespan characteristics.

Another object of the present invention is to provide a lithium manganese oxide symmetric battery system capable of utilizing the 3 V region of lithium manganese oxide and applicable to a symmetric battery system in which the positive and negative electrodes are the same.

However, the problems to be solved by the present invention are not limited to those mentioned above, and other problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

The liquid electrolyte for a lithium secondary battery according to an aspect of the present invention includes a high concentration of a sulfonylimide compound.

In one embodiment, the molar concentration of the sulfonylimide compound may be 15 m to 25 m.

In one embodiment, the sulfonylimide compound is lithium bis (trifluoromethanesulfonyl) imide (Lithium bis (Trifluoromethanesulfonyl) imide; LiTFSI), lithium bis (perfluoroethylsulfonyl) imide (Lithium bis (perfluoroethylsulfonyl) imide; BETI), lithium bis (fluorosulfonyl) imide, lithium bis [(perfluoroalkyl) sulfonyl] imide (Lithium Bis [(perfluoroalkyl) )sulfonyl]imide), lithium poly[4,4'-(hexafluoroisopropylidene)diphenoxy]sulfonylimide (lithium poly[4,4'-(hexafluoroisopropylidene)diphenoxy]sulfonylimide; LiPHFIPSI) and lithium Bis (pentafluoroethanesulfonyl) imide (Lithium bis (pentafluoroethanesulfonyl) imide; LiPFSI) may include at least one selected from the group consisting of.

In one embodiment, the sulfonylimide-based compound may be 81% to 88% by weight of the liquid electrolyte for a lithium secondary battery.

In one embodiment, a lithium salt, an aqueous solvent, or both may be further included.

In one embodiment, the aqueous solvent may be 12% to 19% by weight in the liquid electrolyte for the lithium secondary battery.

In one embodiment, the lithium salt is 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, LiSCN, LiC(CF ₃ SO ₂ ) ₃ , chloroborane lithium, lower aliphatic lithium carboxylate, and lithium 4 phenyl borate containing at least one selected from the group consisting of I can.

A lithium manganese oxide symmetric battery system according to another aspect of the present invention includes a liquid electrolyte for a lithium secondary battery according to an aspect of the present invention; A positive electrode including lithium manganese oxide coated with a carbon-based material; And a negative electrode including the same material as the positive electrode and disposed symmetrically to the positive electrode.

In one embodiment, the carbon-based material is graphite, graphene, carbon nanotube, carbon nanorod, carbon fiber, carbon black, acetylene black, thermal black, graphite, diamond, diamond-like carbon (diamond like carbon; DLC), fullerene (C60), coke, pyrolysis carbon (pyrolitic carbon), carbon aerogel (carbon aerogel), and may include at least one selected from the group consisting of activated carbon.

In one embodiment, the carbon-based material may be 4% to 7% by weight of the positive electrode.

In one embodiment, the thickness of the carbon-based material may be 1 nm to 3 nm.

In one embodiment, the lithium manganese oxide symmetric battery system may be one in which water is not decomposed at a pH in a neutral region.

In one embodiment, the lithium manganese oxide symmetric battery system, when the charging cycle is 100 to 300 times, and the charge/discharge rate (C-rate) is 10 C, the specific capacity (capacity) is 10 mAh / g to 70 It can be mAh/g.

In one embodiment, the lithium manganese oxide symmetric battery system may have a rate-binding performance of 10C/1C≥95%, 20C/1C≥90%, and a 500 cycle capacity retention rate of ≥70%.

In the liquid electrolyte for a lithium secondary battery according to an embodiment of the present invention, water is not decomposed even at neutral pH by using an aqueous solution containing a high concentration sulfonylimide compound as an electrolyte, and the lithium manganese oxide electrode material is reversible to Li ions. Can be saved as Therefore, it shows excellent rate-limiting properties, and stability can be secured by using water as a solvent.

By including the liquid electrolyte for a lithium secondary battery according to an embodiment of the present invention, it is possible to stably implement a lithium manganese oxide symmetric battery system having the same positive electrode and negative electrode. In particular, by including a liquid electrolyte having a high concentration, it exhibits better rate-limiting properties than when an organic electrolyte is included, and stability can be secured by using water, not a non-aqueous solvent, as a solvent.

1 is a graph showing battery life characteristics and capacity characteristics of Example (WIS), Comparative Example 1 (Org), and Comparative Example 2 (Aq) of the present invention.
2 is a graph showing battery low-temperature characteristics of Example (WIS), Comparative Example 1 (Org), and Comparative Example 3 (Ni-MH) of the present invention.
Figure 3 is a graph showing the rate characteristics results of charging and discharging the batteries of Example and Comparative Example 1 (Org) of the present invention 10 times, 20 times 30 times at 0.2C, 0.5C, 1C, 2C, 3C, 5C and 10C to be.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, terms used in the present specification are terms used to properly express a preferred embodiment of the present invention, which may vary depending on the intention of users or operators, or customs in the field to which the present invention belongs. Accordingly, definitions of these terms should be made based on the contents throughout the present specification. The same reference numerals in each drawing indicate the same members.

Throughout the specification, when a member is said to be positioned "on" another member, this includes not only the case where a member is in contact with another member, but also the case where another member exists between the two members.

Throughout the specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components.

Hereinafter, a liquid electrolyte for a lithium secondary battery of the present invention and a lithium manganese oxide symmetric battery system including the same will be described in detail with reference to Examples and drawings. However, the present invention is not limited to these examples and drawings.

The liquid electrolyte for a lithium secondary battery according to an aspect of the present invention includes a high concentration of a sulfonylimide compound.

In one embodiment, the molar concentration of the sulfonylimide compound may be 15 m to 25 m. If the molar concentration of the sulfonylimide-based compound is less than 15 m, water decomposition may be suppressed and lifespan characteristics may be poor, and if it exceeds 25 m, the conductivity may be lowered.

In the liquid electrolyte for a lithium secondary battery according to an embodiment of the present invention, water is not decomposed even at neutral pH by using an aqueous solution containing a high concentration sulfonylimide compound as an electrolyte, and the lithium manganese oxide electrode material is reversible to Li ions. Can be saved as Therefore, it shows excellent rate-limiting properties, and stability can be secured by using water as a solvent.

In one embodiment, the sulfonylimide compound is lithium bis (trifluoromethanesulfonyl) imide (Lithium bis (Trifluoromethanesulfonyl) imide; LiTFSI), lithium bis (perfluoroethylsulfonyl) imide (Lithium bis (perfluoroethylsulfonyl) imide; BETI), lithium bis (fluorosulfonyl) imide, lithium bis [(perfluoroalkyl) sulfonyl] imide (Lithium Bis [(perfluoroalkyl) )sulfonyl]imide), lithium poly[4,4'-(hexafluoroisopropylidene)diphenoxy]sulfonylimide (lithium poly[4,4'-(hexafluoroisopropylidene)diphenoxy]sulfonylimide; LiPHFIPSI) and lithium Bis (pentafluoroethanesulfonyl) imide (Lithium bis (pentafluoroethanesulfonyl) imide; LiPFSI) may include at least one selected from the group consisting of.

In one embodiment, the sulfonylimide-based compound is not particularly limited as long as it has a structure in which small lithium ions are coordinated with an anionic group having a large size. The sulfonylimide-based compound may have stable high-temperature storage and cycle characteristics as well as low-temperature characteristics.

In one embodiment, the sulfonylimide-based compound may be 81% to 88% by weight of the liquid electrolyte for a lithium secondary battery. When the sulfonylimide-based compound is less than 81% by weight of the liquid electrolyte for a lithium secondary battery, water may be decomposed, it is difficult to expect improvement of low-temperature characteristics, and when it is more than 88% by weight, a lot of lithium in the vicinity of the anode during the charging process It provides an ion supply, thereby limiting the concentration gradient and depletion of lithium ions in the electrolyte.

In one embodiment, a lithium salt, an aqueous solvent, or both may be further included. The aqueous solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move. The lithium salt acts as a source of lithium ions in the battery to enable basic lithium battery operation.

In one embodiment, the aqueous solvent may be 12% to 19% by weight in the liquid electrolyte for the lithium secondary battery. When the aqueous solvent is less than 12% by weight of the liquid electrolyte for a lithium secondary battery, low-temperature characteristics are not good, and when it is more than 19% by weight, water as a solvent may react on the electrode surface to generate hydrogen gas.

In one embodiment, the lithium salt is 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, LiSCN, LiC(CF ₃ SO ₂ ) ₃ , chloroborane lithium, lower aliphatic lithium carboxylate, and lithium 4 phenyl borate containing at least one selected from the group consisting of I can.

The liquid electrolyte for a lithium secondary battery according to an embodiment of the present invention may be a solution having a pH of 4 to 12 stably containing lithium ions and containing water and a lithium salt. When the pH of the electrolyte is out of the above range, the oxygen generation region may have a lithium ion intercalation and desorption potential of the positive electrode active material, and the stable operation region and the hydrogen generation region may deviate from the hydrogen generation potential of the negative electrode active material.

The liquid electrolyte for a lithium secondary battery according to an embodiment of the present invention has excellent safety, high ionic conductivity, and low cost of manufacturing a battery using an aqueous electrolyte compared to an organic electrolyte. In addition, it has excellent electrical properties such as higher energy density than when using an organic electrolyte.

A lithium manganese oxide symmetric battery system according to another aspect of the present invention includes a liquid electrolyte for a lithium secondary battery according to an aspect of the present invention; A positive electrode including lithium manganese oxide coated with a carbon-based material; And a negative electrode including the same material as the positive electrode and disposed symmetrically to the positive electrode. The lithium manganese oxide symmetric battery system of the present invention may be a symmetric lithium manganese oxide (Symmetric Lithium Manganese Oxide cell; SLMO).

By including the liquid electrolyte for a lithium secondary battery according to an embodiment of the present invention, it is possible to stably implement a lithium manganese oxide symmetric battery system having the same positive electrode and negative electrode. In particular, by including a liquid electrolyte having a high concentration, it exhibits better rate-limiting properties than when an organic electrolyte is included, and stability can be secured by using water, not a non-aqueous solvent, as a solvent.

In one embodiment, the lithium manganese oxide may be used as a positive electrode active material and a negative electrode active material, has a spinel structure and a composition formula of Li _1+x Mn _2-xy M _y O ₄ [here, -0.3 <x <0.2, 0 <y <0.1, M may be one or more elements selected from the group consisting of Al, Mg, Ni, Co, Fe, Ti, V, Zr, and Zn].

In one embodiment, the carbon-based material is graphite, graphene, carbon nanotube, carbon nanorod, carbon fiber, carbon black, acetylene black, thermal black, graphite, diamond, diamond-like carbon (diamond like carbon; DLC), fullerene (C60), coke, pyrolysis carbon (pyrolitic carbon), carbon aerogel (carbon aerogel), and may include at least one selected from the group consisting of activated carbon.

In one embodiment, the carbon-based material may be 4% to 7% by weight of the positive electrode. When the carbon-based material is less than 4% by weight of the positive electrode, the efficiency may decrease, and when it exceeds 7% by weight, the capacity may decrease.

In one embodiment, since the positive electrode and the negative electrode are the same material used in a lithium manganese oxide symmetric battery system, the carbon-based material may be the same as the content contained in the negative electrode.

In one embodiment, the lithium manganese oxide without the coating of the carbon-based material is not implemented due to structural collapse in the 3 V period even when the organic carbonate-based electrolyte is used.

In one embodiment, the thickness of the carbon-based material may be 1 nm to 3 nm. When the thickness of the carbon-based material is less than 1 nm, the capacity of the 3 V region may decrease, and when the thickness of the carbon-based material exceeds 3 nm, the capacity may decrease by interfering with the infiltration/desorption of lithium ions into the active material.

As for the positive and negative electrodes, a positive electrode and a negative electrode are respectively manufactured according to a conventional method used in manufacturing a lithium battery. It may be manufactured with a 2032 coin cell. After raising the positive electrode on the cell case, after injecting the electrolyte, the separator and the negative electrode are sequentially raised, a gasket, a spacer, and a spring are put on the cap to assemble the battery.

In one embodiment, the lithium manganese oxide symmetric battery system may be one in which water is not decomposed at a pH in a neutral region. When using existing aqueous electrolytes, for example, Li ₂ SO ₄ 1 M, LiNO ₃ 5 M, capacity is not realized due to water decomposition, but when the high concentration liquid electrolyte of the present invention is included, it is successfully used in the neutral pH region. Water is not decomposed and the lithium manganese oxide electrode material can reversibly store lithium ions.

In one embodiment, the lithium manganese oxide symmetric battery system, when the charging cycle is 100 to 300 times, and the charge/discharge rate (C-rate) is 10 C, the specific capacity (capacity) is 10 mAh / g to 70 It can be mAh/g.

In one embodiment, the lithium manganese oxide symmetric battery system may have a rate-binding performance of 10C/1C≥95%, 20C/1C≥90%, and a 500 cycle capacity retention rate of ≥70%.

The lithium manganese oxide symmetric battery system according to an embodiment of the present invention may be used in an electric vehicle or a mid- to large-sized battery system for a hybrid electric vehicle.

Hereinafter, the present invention will be described in detail with reference to the following Examples and Comparative Examples. However, the technical idea of the present invention is not limited or limited thereby.

[Example]

A cathode active material slurry was prepared by mixing LiMn ₂ O ₄ cathode active material, super p (conductive material), and carbon subjected to a ball mill process in N-methylpyrrolidone. The positive electrode active material slurry was applied to an aluminum foil current collector to prepare a positive electrode.

The negative electrode was also prepared from the same material as the positive electrode.

Lithium bis (trifluoromethanesulfonyl) imide (Lithium bis (trifluoromethanesulfonyl) imide; LiTFSI) was dissolved in water at a concentration of 21 m to prepare a liquid electrolyte.

It was manufactured as a 2032 coin cell. After raising the positive electrode on the cell case, injecting electrolyte, the separator and negative electrode were sequentially raised, a gasket, a spacer, and a spring were put on the cap to assemble the battery. A symmetrical lithium manganese oxide (SLMO) battery with the same positive and negative electrodes was manufactured using glass fiber as the separator.

[Comparative Example 1]

As for the electrode material, as above, a slurry was prepared using LMO active material, conductive material, and carbon that had undergone a ball mill process, and then applied to an aluminum foil current collector to prepare a positive electrode. The negative electrode was also prepared in the same manner as the positive electrode. It was manufactured with a 2032 coin cell using a PE separator.

[Comparative Example 2]

As for the electrode material, as above, a slurry was prepared using LMO active material, conductive material, and carbon that had undergone a ball mill process, and then applied to a stainless steel foil current collector to manufacture a positive electrode. The negative electrode was also prepared in the same manner as the positive electrode. It was manufactured with a 2032 coin cell using a glass fiber separator.

[Comparative Example 3]

A commercially available lithium manganese oxide (SLMO) battery was prepared.

1 is a graph showing battery life characteristics and capacity characteristics of Example (WIS), Comparative Example 1 (Org), and Comparative Example 2 (Aq) of the present invention. As shown in FIG. 1, since reversible charging and discharging is possible, it can be seen that it is useful as a lithium secondary battery.

2 is a graph showing battery low-temperature characteristics of Example (WIS), Comparative Example 1 (Org), and Comparative Example 3 (Ni-MH) of the present invention. The low-temperature characteristics are measured by measuring the discharge capacity by varying the temperature, respectively. As shown in FIG. 2, in the case of Comparative Example 1 (Org) and Comparative Example 3 (Ni-MH), the discharge capacity rapidly decreases due to the decrease in the relative capacity (Q _T / Q _25°C ) of the electrolyte in a low temperature state. There was this. However, when using a lithium ion battery to which a liquid electrolyte according to an embodiment of the present invention is applied, it can be seen that characteristics are improved compared to Comparative Examples 1 and 3 in a temperature environment of -30°C and -20°C.

Figure 3 is a graph showing the rate characteristics results of charging and discharging the batteries of Example and Comparative Example 1 (Org) of the present invention 10 times, 20 times 30 times at 0.2C, 0.5C, 1C, 2C, 3C, 5C and 10C to be. As shown in FIG. 3, it can be seen that the battery of Example 1 exhibits excellent life characteristics with little decrease in capacity during charging and discharging compared to Comparative Example 1.

The lithium manganese oxide symmetric battery system of the present invention is excellent in safety, can reduce process costs during a manufacturing process, and can provide a battery using a liquid electrolyte that has high environmental affinity and can provide excellent conductivity. In addition, a battery using a graphite surface-treated lithium manganese oxide positive electrode and negative electrode exhibits remarkably improved lifespan characteristics, capacity, and initial efficiency characteristics.

As described above, although the embodiments have been described by the limited embodiments and drawings, various modifications and variations are possible from the above description by those of ordinary skill in the art. For example, even if the described techniques are performed in a different order from the described method, and/or the described components are combined or combined in a form different from the described method, or are replaced or substituted by other components or equivalents. Appropriate results can be achieved. Therefore, other implementations, other embodiments, and claims and equivalents fall within the scope of the claims to be described later.

Claims (16)

delete delete delete delete delete delete delete A liquid electrolyte for a lithium secondary battery containing a sulfonylimide-based compound having a molar concentration of 15 m to 25 m;
A positive electrode including lithium manganese oxide coated with a carbon-based material; And
A cathode comprising the same material as the anode and disposed symmetrically to the anode;
Including,
The sulfonylimide-based compound is 81% to 88% by weight of the liquid electrolyte for a lithium secondary battery,
The lithium manganese oxide includes a positive electrode active material and a negative electrode active material, has a spinel structure,
The composition formula is LiMn ₂ O ₄ or Li _1+x Mn _2-xy M _y O ₄ [here, -0.3 <x <0.2, 0 <y <0.1, M is Al, Mg, Ni, Co, Fe, Ti, V , Zr and at least one element selected from the group consisting of Zn],
Symmetric Lithium Manganese Oxide cell (SLMO),
Lithium manganese oxide symmetric battery system.
The method of claim 8,
The carbon-based material is graphite, graphene, carbon nanotube, carbon nanorod, carbon fiber, carbon black, acetylene black, thermal black, graphite, diamond, diamond like carbon (DLC) ), fullerene (C60), coke, pyrolysis carbon (pyrolitic carbon), carbon aerogel (carbon aerogel) and comprising at least one selected from the group consisting of activated carbon,
Lithium manganese oxide symmetric battery system.
The method of claim 8,
The carbon-based material is from 4% to 7% by weight of the positive electrode,
Lithium manganese oxide symmetric battery system.
The method of claim 8,
The thickness of the carbon-based material is 1 nm to 3 nm,
Lithium manganese oxide symmetric battery system.
The method of claim 8,
The lithium manganese oxide symmetric battery system is that water does not decompose at the pH of the neutral region,
Lithium manganese oxide symmetric battery system.
The method of claim 8,
The lithium manganese oxide symmetric battery system,
When the charging cycle is 100 to 300 times, and the charge/discharge rate (C-rate) is 10 C, the specific capacity (capacity) is 10 mAh/g to 70 mAh/g,
Lithium manganese oxide symmetric battery system.
The method of claim 8,
The lithium manganese oxide symmetric battery system,
The rate-binding performance is 10C/1C≥95%, 20C/1C≥90%, and the 500 cycle capacity retention rate is ≥70%,
Lithium manganese oxide symmetric battery system. The method of claim 8,
The sulfonylimide-based compound is lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium bis (perfluoroethylsulfonyl) imide (Lithium bis (perfluoroethylsulfonyl)). imide; BETI), lithium bis (fluorosulfonyl) imide), lithium bis [(perfluoroalkyl) sulfonyl] imide (Lithium Bis[(perfluoroalkyl)sulfonyl]imide), Lithium poly[4,4'-(hexafluoroisopropylidene)diphenoxy]sulfonylimide (lithium poly[4,4'-(hexafluoroisopropylidene)diphenoxy]sulfonylimide; LiPHFIPSI) and lithium bis(pentafluoroethane) Sulfonyl) imide (Lithium bis (pentafluoroethanesulfonyl) imide; LiPFSI) containing at least any one selected from the group consisting of,
Lithium manganese oxide symmetric battery system.
The method of claim 8,
The liquid electrolyte for a lithium secondary battery further includes a lithium salt, an aqueous solvent, or both,
The aqueous solvent is 12% to 19% by weight of the liquid electrolyte for a lithium secondary battery,
The lithium salt is 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, It comprises at least any one selected from the group consisting of CF ₃ SO ₃ Li, LiSCN, LiC(CF ₃ SO ₂ ) ₃ , lithium chloroborane, lithium lower aliphatic carboxylic acid, and lithium 4 phenyl borate,
Lithium manganese oxide symmetric battery system.

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