Battery

Abstract

The invention discloses a battery. The electrode according to the present disclosure is a battery having a positive electrode layer, an electrolyte layer containing MeFSA (dimethylaminosulfonyl fluoride) and LiFSI (lithium bis (fluorosulfonyl) imide), and a negative electrode layer containing an Si-based active material as a negative electrode active material, in this order.

Description

Technical Field

[0001] The present disclosure relates to a battery. Background Art

[0002] Regarding a battery containing a Si-based active material as a negative electrode active material as disclosed in Japanese Unexamined Patent Application Publication No. 2023-044620, various technologies have been proposed. Summary of the Invention

[0003] When a Si-based active material is used as a negative electrode active material in a liquid battery, there is room for improvement from the viewpoint of reducing the irreversible capacity.

[0004] The present disclosure has been made in view of the above actual situation, and its main object is to provide a battery capable of reducing the irreversible capacity.

[0005] That is, the present disclosure includes the following aspects.

[0006] <1>A battery having a positive electrode layer, an electrolyte layer, and a negative electrode layer in this order,

[0007] wherein the electrolyte layer contains MeFSA (dimethylaminosulfonyl fluoride) and LiFSI (lithium bis(fluorosulfonyl)imide),

[0008] and the negative electrode layer contains a Si-based active material as a negative electrode active material.

[0009] <2>The battery according to <1>, wherein the molar ratio of LiFSI to MeFSA is LiFSI:MeFSA = 1:12 to 1:3.

[0010] <3>The battery according to <1> or <2>, wherein the negative electrode active material is a porous silicon inclusion compound.

[0011] <4>The battery according to any one of <1> to <3>,

[0012] wherein the negative electrode active material is negative electrode active material particles,

[0013] and the D50 of the negative electrode active material particles is 0.7 μm or less.

[0014] <5>The battery according to any one of <1> to <4>,

[0015] wherein the negative electrode active material is negative electrode active material particles,

[0016] and the specific surface area of the negative electrode active material particles is 25 to 60 m 2 / g.

[0017] The battery of the present disclosure can reduce the irreversible capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention are described with reference to the accompanying drawings, in which like reference numerals represent like elements, and wherein:

[0019] Figure 1 It is a diagram showing the difference in the Li metal negative electrode potential in the case of a conventional electrolyte and in the case of an electrolyte using MeFSA (dimethylaminosulfonyl fluoride) as a solvent in the present disclosure.

[0020] Figure 2 It is a diagram showing the initial coulombic efficiency, average coulombic efficiency, and discharge capacity retention rate measured in Examples 7 to 9, 13 to 15, and Comparative Examples 1 to 6. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] Hereinafter, embodiments of the present disclosure will be described. Furthermore, matters necessary for implementing the present disclosure other than those specifically mentioned in this specification (for example, the general configuration and manufacturing process of a battery that do not characterize the present disclosure) can be grasped as design matters of those skilled in the art based on the prior art in the art. The present disclosure can be implemented based on the content disclosed in this specification and the common general knowledge in the art.

[0022] In the present disclosure, unless otherwise specified, the average particle diameter (D50) of the particles is the value of the particle diameter (median diameter) at the cumulative value of 50% in the volume-based particle size distribution measured by laser diffraction-scattering particle size distribution measurement.

[0023] In the present disclosure, a battery is provided, which is a battery having a positive electrode layer, an electrolyte layer, and a negative electrode layer in this order.

[0024] The electrolyte layer contains MeFSA (dimethylaminosulfonyl fluoride) and LiFSI (lithium bis(fluorosulfonyl)imide).

[0025] The negative electrode layer contains a Si-based active material as a negative electrode active material.

[0026] At the interface between the negative electrode of the battery and the electrolyte, a film formed mainly by the reductive decomposition of the electrolyte during charging, namely SEI (Solid Electrolyte Interphase), partially collapses due to the volume change during charge and discharge of the Si-based active material. During recharging after the collapse, a thick, uneven, and multi-layered SEI with a distorted shape is formed on the surface. As a result, the function of the SEI as an interface protective layer deteriorates, promoting the reductive decomposition of the electrolyte. Since the growth of the SEI continuously occurs due to repeated charge and discharge, the resistance of the battery increases with charge and discharge, resulting in a decrease in the coulombic efficiency and capacity retention rate of the battery.

[0027] Figure 1 This is a diagram showing the difference in the Li metal negative electrode potential in the case of a conventional electrolyte and an electrolyte using MeFSA (dimethylaminosulfuryl fluoride) as a solvent in the present disclosure.

[0028] As Figure 1 shown, conventionally, the SEI compensated for the gap between the potential window of the electrolyte and the Li metal negative electrode potential. However, in the present disclosure, by bringing the Li metal negative electrode potential closer to the reduction-side potential window of the electrolyte (upshifting), the electrode reaction can proceed easily even without the formation of SEI. In addition, the reduction decomposition of the electrolyte is thermodynamically suppressed, and the state of the electrolyte is stable. The same effect can be obtained even when changing from the Li metal negative electrode to a high-capacity negative electrode (a negative electrode containing a Si-based active material).

[0029] The battery of the present disclosure sequentially includes a positive electrode, an electrolyte layer, and a negative electrode.

[0030] [Positive Electrode]

[0031] The positive electrode includes a positive electrode layer. The positive electrode optionally includes a positive electrode current collector.

[0032] [Positive Electrode Layer]

[0033] The positive electrode layer includes a positive electrode active material and may optionally include a solid electrolyte, a conductive material, a binder, etc.

[0034] Examples of the positive electrode active material include lithium, lithium nickel cobalt aluminum oxide (NCA), LiCoO2, LiNi x Co 1-x O2 (0 < x < 1), Li(Ni 0.8 Co 0.1 Mn 0.1 )O2 (NCM811), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiMnO2, LiMn2O4, LiNiO2, LiVO2, a Li-Mn spinel substituted with a foreign element, lithium titanate, lithium metal phosphate, LiCoN, Li2SiO3, and Li4SiO4, etc. The Li-Mn spinel substituted with a foreign element is, for example, LiMn 1.5 Ni 0.5 O4, LiMn 1.5 Al 0.5 O4, LiMn 1.5 Mg 0.5 O4, LiMn 1.5 Co 0.5 O4, LiMn1.5 Fe 0.5 O4 and LiMn 1.5 Zn 0.5 O4 and the like. Lithium titanate is, for example, Li4Ti5O 12 and the like. Lithium metal phosphates are, for example, LiFePO4, LiMnPO4, LiCoPO4, and LiNiPO4 and the like.

[0035] The shape of the positive electrode active material is not particularly limited and may be particulate (positive electrode active material particles).

[0036] A coating containing a Li ion conductive oxide may also be formed on the surface of the positive electrode active material. This is because the reaction between the positive electrode active material and the solid electrolyte can be suppressed.

[0037] Examples of the Li ion conductive oxide include LiNbO3, Li4Ti5O 12 and Li3PO4 and the like. The thickness of the coating is, for example, 0.1 nm or more and may be 1 nm or more. On the other hand, the thickness of the coating is, for example, 100 nm or less and may be 20 nm or less. The coverage rate of the coating on the surface of the positive electrode active material is, for example, 70% or more and may be 90% or more.

[0038] Examples of the solid electrolyte include oxide-based solid electrolytes and sulfide-based solid electrolytes.

[0039] Examples of the sulfide-based solid electrolyte include a solid electrolyte containing a Li element, an M element (M is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In), and an S element. In addition, the sulfide-based solid electrolyte may further contain at least one of an O element and a halogen element.

[0040] Examples of the sulfide-based solid electrolyte include Li2S-P2S5, Li2S-SiS2, LiX-Li2S-SiS2, LiX-Li2S-P2S5, LiX-Li2O-Li2S-P2S5, LiX-Li2S-P2O5, LiX-Li3PO4-P2S5, and Li3PS4 and the like. Furthermore, the description of "Li2S-P2S5" means a material formed using a raw material composition containing Li2S and P2S5, and the same applies to other descriptions.

[0041] In addition, "X" in the above LiX represents a halogen element. Examples of the halogen element include an F element, a Cl element, a Br element, and an I element and the like. One or two or more kinds of LiX may be included in the raw material composition containing the above LiX. In the case of including two or more kinds of LiX, the mixing ratio of the two or more kinds of LiX is not particularly limited.

[0042] The molar ratio of each element in the sulfide-based solid electrolyte can be controlled by adjusting the content of each element in the raw materials. In addition, the molar ratio and composition of each element in the sulfide-based solid electrolyte can be measured, for example, by ICP emission spectrometry.

[0043] The sulfide-based solid electrolyte can be a sulfide glass, a crystallized sulfide glass (glass ceramic), or a crystalline material obtained by solid-phase reaction treatment of a raw material composition.

[0044] The crystalline state of the sulfide-based solid electrolyte can be confirmed, for example, by powder X-ray diffraction measurement using CuKα rays on the sulfide-based solid electrolyte.

[0045] The sulfide glass can be obtained by subjecting a raw material composition (for example, a mixture of Li2S and P2S5) to an amorphous treatment. Examples of the amorphous treatment include mechanical grinding.

[0046] The glass ceramic can be obtained, for example, by heat-treating the sulfide glass.

[0047] The heat treatment temperature only needs to be a temperature higher than the crystallization temperature (Tc) of the sulfide glass observed by thermal analysis, and is usually 195 °C or higher. On the other hand, the upper limit of the heat treatment temperature is not particularly limited.

[0048] The crystallization temperature (Tc) of the sulfide glass can be measured by differential thermal analysis (DTA).

[0049] The heat treatment time is not particularly limited as long as it is a time that can obtain the desired crystallinity of the glass ceramic. For example, it is in the range of 1 minute to 24 hours, and among them, the range of 1 minute to 10 hours can be cited.

[0050] The method of heat treatment is not particularly limited. For example, a method using a firing furnace can be cited.

[0051] Examples of the oxide-based solid electrolyte include substances having a garnet-type crystal structure containing a Li element, a La element, an A element (A is at least one of Zr, Nb, Ta, and Al), and an O element. As the oxide-based solid electrolyte, for example, Li2O - B2O3 - P2O5, Li2O - SiO2, Li2O - B2O3, Li 1.3 Al 0.3 Ti 0.7 (PO4)3, Li5La3Ta2O 12 , Li7La3Zr2O 12 , Li6BaLa2Ta2O 12, Li 3.6 Si 0.6 P 0.4 O4, Li4SiO4, Li3PO4, and Li 3+x PO 4-x N x (1 ≤ x ≤ 3), etc.

[0052] From the viewpoint of good processability, the shape of the solid electrolyte can be particulate.

[0053] In addition, the average particle diameter (D50) of the particles of the solid electrolyte is not particularly limited, but the lower limit can be 0.5 μm or more, and the upper limit can be 2 μm or less.

[0054] The content of the solid electrolyte in the positive electrode layer is not particularly limited, and when the total mass of the positive electrode layer is set to 100% by mass, for example, it can be in the range of 1% by mass to 80% by mass.

[0055] The solid electrolyte can be used alone or in combination of two or more. In addition, when two or more solid electrolytes are used, two or more solid electrolytes can be mixed.

[0056] As the conductive material, known conductive materials can be used, such as carbon materials and metal particles. As the carbon materials, for example, acetylene black (AB), Ketjen black (KB), furnace black, vapor grown carbon fiber (VGCF), carbon nanotubes, and carbon nanofibers can be mentioned. Among them, from the viewpoint of electron conductivity, it can be at least one selected from KB, VGCF, carbon nanotubes, and carbon nanofibers. As the metal particles, particles such as Ni, Cu, Fe, and stainless steel (SUS) can be mentioned.

[0057] The content of the conductive material in the positive electrode layer is not particularly limited.

[0058] As the binder, polyamide-based resins, acrylonitrile-butadiene rubber (ABR), butadiene rubber (BR), polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), and styrene-butadiene rubber (SBR) can be exemplified. The content of the binder in the positive electrode layer is not particularly limited.

[0059] The thickness of the positive electrode layer is not particularly limited.

[0060] The positive electrode layer can be formed by a conventionally known method.

[0061] For example, by putting the positive electrode active material and other components added as needed into a solvent and stirring, a slurry for the positive electrode layer is prepared, and by coating the slurry for the positive electrode layer on one surface of a support such as a positive electrode current collector and drying it, a positive electrode layer is obtained.

[0062] Solvents include, for example, butyl acetate, butyl butyrate, heptane, N-methyl-2-pyrrolidone, and the like.

[0063] The method of coating the slurry for the positive electrode layer on one surface of a support such as a positive electrode current collector is not particularly limited, and examples include the doctor blade method, the metal mask printing method, the electrostatic coating method, the dip coating method, the spray coating method, the roll coating method, the gravure coating method, and the screen printing method.

[0064] As the support, a self-supporting support can be appropriately selected and used, and there is no particular limitation. For example, metal foils such as Cu and Al can be used.

[0065] [Positive Electrode Current Collector]

[0066] As the positive electrode current collector, a known metal that can be used as a current collector of a battery can be used. Examples of such metals include metal materials containing one or more elements selected from Cu, Ni, Al, V, Au, Pt, Mg, Fe, Ti, Co, Cr, Zn, Ge, and In. Examples of the positive electrode current collector include SUS, aluminum, nickel, iron, titanium, and carbon.

[0067] The form of the positive electrode current collector is not particularly limited, and various forms such as foil shape and mesh shape can be adopted.

[0068] [Electrolyte Layer]

[0069] The electrolyte layer contains an electrolytic solution, and the electrolytic solution contains MeFSA (dimethylaminosulfonyl fluoride) represented by the following formula (1) as a solvent and LiFSI (lithium bis(fluorosulfonyl)imide) represented by the following formula (2) as an electrolyte salt.

[0070]

[0071] The molar ratio of LiFSI to MeFSA can be LiFSI:MeFSA = 1:12 to 1:3.

[0072] The electrolyte layer can have a separator or the like for holding the electrolytic solution and preventing contact between the positive electrode layer and the negative electrode layer. The thickness of the electrolyte layer is not particularly limited. For example, it can be 0.1 μm or more or 1 μm or more, and can be 2 mm or less or 1 mm or less.

[0073] The separator may be a separator made of resins such as polyethylene (PE), polypropylene (PP), polyester, and polyamide. The separator may be a single-layer structure or a multi-layer structure. As a multi-layer structure separator, for example, a 2-layer structure of PE / PP, or a 3-layer structure of PP / PE / PP or PE / PP / PE, etc. may be mentioned. The separator may also be made of non-woven fabrics such as cellulose non-woven fabrics, resin non-woven fabrics, and glass fiber non-woven fabrics.

[0074] [negative electrode]

[0075] The negative electrode includes a negative electrode layer and optionally includes a negative electrode current collector.

[0076] [Negative electrode layer]

[0077] The negative electrode layer contains a Si-based active material as a negative electrode active material, and contains the above-mentioned conductive material, the above-mentioned binder, and the like as necessary.

[0078] The Si-based active material may be a simple Si, Si oxide, Si-C complex, Si alloy, etc. The Si-based active material may be porous Si. The Si-based active material may be diamond-type crystalline Si, Si inclusion compound, amorphous Si, etc., and may be a porous Si inclusion compound. The Si inclusion compound may be a type I inclusion compound or a type II inclusion compound.

[0079] The negative electrode active material may be negative electrode active material particles.

[0080] The average particle size D50 of the negative electrode active material particles may be 0.5 μm or more, 2.6 μm or less, or 0.7 μm or less.

[0081] The specific surface area of ​​the negative electrode active material particles can be 1m 2 / g or more, can be 25m 2 / g or more, can be 60m 2 / g or less, can be 33m 2 / g or less.

[0082] The thickness of the negative electrode layer is not particularly limited.

[0083] [Negative electrode current collector]

[0084] The material of the negative electrode collector may be, for example, SUS, copper, and nickel. As the form of the negative electrode collector, for example, foil and plate may be mentioned. The top view shape of the negative electrode collector is not particularly limited, and for example, a circular shape, an elliptical shape, a rectangular shape, and any polygonal shape may be mentioned. In addition, the thickness of the negative electrode collector varies depending on the shape, and for example, it may be in the range of 1 μm to 50 μm, and may be in the range of 5 μm to 20 μm.

[0085] The battery includes an outer package that houses a positive electrode layer, a negative electrode layer, an electrolyte layer, etc. as needed.

[0086] The material of the outer package is not particularly limited as long as it is stable to the electrolyte, and examples include resins such as polypropylene, polyethylene, and acrylic resins.

[0087] Examples of the shape of the battery include coin type, laminated type, cylindrical type, and square type.

[0088] The battery can be a primary battery or a secondary battery. As the use of the battery, for example, it can be used as a power source for vehicles such as hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), battery electric vehicles (BEV), gasoline vehicles, and diesel vehicles. In particular, it can be used as a driving power source for hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), or battery electric vehicles (BEV). In addition, the battery can be used as a power source for moving bodies other than vehicles (such as trains, ships, and airplanes), and can also be used as a power source for electrical products such as information processing devices.

[0089] (Reference Experimental Examples 1-5)

[0090] [Electrolyte solution]

[0091] In Reference Experimental Example 1, the first electrolyte solution containing LiFSI as an electrolyte salt and MeFSA as a solvent in a molar ratio of LiFSI:MeFSA = 1:12 was used.

[0092] In Reference Experimental Example 2, the second electrolyte solution containing LiFSI as an electrolyte salt and MeFSA as a solvent in a molar ratio of LiFSI:MeFSA = 1:8 was used.

[0093] In Reference Experimental Example 3, the third electrolyte solution containing LiFSI as an electrolyte salt and MeFSA as a solvent in a molar ratio of LiFSI:MeFSA = 1:4 was used.

[0094] In Reference Experimental Example 4, the fourth electrolyte solution containing LiFSI as an electrolyte salt and MeFSA as a solvent in a molar ratio of LiFSI:MeFSA = 1:3 was used.

[0095] In Reference Experimental Example 5, the following electrolyte solution was used as the conventional electrolyte solution. The electrolyte solution contains 1.2 M of LiPF6 as an electrolyte salt and a mixed solvent as a solvent. The mixed solvent is a mixed solvent of ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and fluoroethylene carbonate (FEC).

[0096] [Measurement of Li electrode potential]

[0097] Using a three - electrode cell, the following method was used to measure the Li electrode potential when each electrolyte of Reference Experimental Examples 1 - 5 was used.

[0098] 1 mM of ferrocene (Fc) was added to each electrolyte of Reference Experimental Examples 1 - 5, and a three - electrode cell was prepared with platinum used as the working electrode and Li metal used as the counter electrode and reference electrode.

[0099] Using the three - electrode cell, cyclic voltammetry (CV) measurements were performed in the potential range of 2.5 V - 4 V vs Li / Li + to measure the average redox potential of ferrocene on the working electrode with respect to Li.

[0100] It is known that the redox potential of ferrocene is approximately constant (about 3.2 V vs. Li / Li + ) regardless of the electrolyte concentration and type. Therefore, it is considered that the change in the ferrocene redox potential according to the electrolyte type is due to the change in the electrode potential of Li used as the reference electrode according to the electrolyte type.

[0101] Therefore, the measured "Li - based ferrocene redox potential" can be rewritten as "ferrocene - based Li electrode potential", and thus the ferrocene - based Li electrode potential is shown in Table 1.

[0102] [Calculation of average dissolution - precipitation efficiency]

[0103] Using a two - electrode coin cell, the following method was used to calculate the average dissolution - precipitation efficiency of the Li electrode when each electrolyte of Reference Experimental Examples 1 - 5 was used.

[0104] Using each electrolyte of Reference Experimental Examples 1 - 5, a two - electrode coin cell was prepared with a copper foil used as the working electrode, Li metal used as the counter electrode, and a glass filter used as the separator.

[0105] In the two - electrode coin cell, Li metal was deposited on the copper foil at a current density of 0.5 mAh / cm 2 for 1 hour, and then Li metal was dissolved at the same current density until the voltage reached 0.5 V (cut - off voltage). This process was regarded as one cycle, and the average dissolution - precipitation efficiency of the Li electrode was calculated when this cycle was repeated.

[0106] In Reference Experimental Example 1, the average dissolution and precipitation efficiency after 14 cycles was calculated. In Reference Experimental Example 2, the average dissolution and precipitation efficiency after 19 cycles was calculated. In Reference Experimental Examples 3 to 5, the average dissolution and precipitation efficiency after 20 cycles was calculated. The results are shown in Table 1.

[0107] Table 1

[0108] MeFSA / LiFSI Li Electrode Potential Average Dissolution and Deposition Efficiency (Molar Ratio) <![CDATA[(V vs.Fc / Fc + )]]> (％) Reference Experimental Example 1 12 -2.98 96.3 Reference Experimental Example 2 8 -2.92 97.3 Reference Experimental Example 3 4 -2.89 97.5 Reference Experimental Example 4 3 -2.88 98.1 Reference Experimental Example 5 - -3.14 95.4

[0109] As shown in Table 1, it can be seen that compared with Reference Experimental Example 5, the Li electrode potential increased and shifted upward in Reference Experimental Examples 1 to 4. It can also be seen that compared with Reference Experimental Example 5, the average dissolution and precipitation efficiency increased in Reference Experimental Examples 1 to 4. Therefore, by using an electrolyte solution containing LiFSI as the electrolyte salt and MeFSA as the solvent, the reactivity of the Li electrode becomes higher.

[0110] (Examples 1 to 12, Comparative Examples 1 to 3)

[0111] [Fabrication of half-cell]

[0112] In each of Examples 1 to 12 and Comparative Examples 1 to 3, a half-cell having the following negative electrode layer, negative electrode current collector, counter electrode, and electrolyte solution was fabricated.

[0113] A negative electrode layer was prepared, which contained a Si-based active material as a negative electrode active material, a polyamide-based resin as a binder, KB and VGCF as conductive materials in a ratio of 82:12:5:1 (wt%). As the polyamide-based resin, a resin obtained by thermally curing a polyamic acid solution at a high temperature was used.

[0114] As the Si-based active materials in Examples 1 to 12 and Comparative Examples 1 to 3, the Si-based active materials shown in Table 2 were used.

[0115] The particles of the first diamond-type crystalline Si shown in Table 2 had an average particle size D50 of 2.6 μm and a specific surface area of 1 m 2 / g.

[0116] The particles of the second diamond-type crystalline Si (nanosized crystalline Si) shown in Table 2 had an average particle size D50 of 0.5 μm and a specific surface area of 25 m 2 / g.

[0117] The particles of the porous type-II Si inclusion (pcSi) shown in Table 2 had an average particle size D50 of 0.7 μm and a specific surface area of 33 m 2 / g.

[0118] A Cu foil was used as the negative electrode current collector.

[0119] Li metal was used as the counter electrode.

[0120] In Examples 1 to 3, the first electrolyte used in Reference Experimental Example 1 was used.

[0121] In Examples 4 to 6, the second electrolyte used in Reference Experimental Example 2 was used.

[0122] In Examples 7 to 9, the third electrolyte used in Reference Experimental Example 3 was used.

[0123] In Examples 10 to 12, the fourth electrolyte used in Reference Experimental Example 4 was used.

[0124] In Comparative Examples 1 to 3, the conventional electrolyte used in Reference Experimental Example 5 was used.

[0125] [Calculation of the average coulombic efficiency based on 50 cycles of a half-cell]

[0126] In each of Examples 1 to 12 and Comparative Examples 1 to 3, 1200 mAh / g was defined as the charging capacity, and charge and discharge were performed for 50 cycles on each half-cell under the conditions of a temperature of 25 °C and 0.1 C, and the average coulombic efficiency of each half-cell was calculated. The results are shown in Table 2.

[0127] Coulombic efficiency (%) = (discharge capacity / charging capacity) × 100

[0128] Table 2

[0129] MeFSA / LiFSI Si-based Active Material Average Coulombic Efficiency (Molar Ratio) (％) Example 1 12 First Diamond-type Crystalline Si 99.1 Example 2 12 Second Diamond-type Crystalline Si 99.5 Example 3 12 Porous Type-II Si Inclusion 98.9 Example 4 8 First Diamond-type Crystalline Si 99.0 Example 5 8 Second Diamond-type Crystalline Si 99.5 Example 6 8 Porous Type-II Si Inclusion 99.3 Example 7 4 First Diamond-type Crystalline Si 99.3 Example 8 4 Second Diamond-type Crystalline Si 99.5 Example 9 4 Porous Type-II Si Inclusion 99.1 Example 10 3 First Diamond-type Crystalline Si 99.4 Example 11 3 Second Diamond-type Crystalline Si 99.5 Example 12 3 Porous Type-II Si Inclusion 99.4 Comparative Example 1 - First Diamond-type Crystalline Si 98.9 Comparative Example 2 - Second Diamond-type Crystalline Si 98.6 Comparative Example 3 - Porous Type-II Si Inclusion 98.8

[0130] As shown in Table 2, it was confirmed that the average coulombic efficiency in the half-cell increased by 0.1 to 0.6% compared with the conventional electrolyte.

[0131] (Examples 13 to 15, Comparative Examples 4 to 6)

[0132] [Fabrication of a full-cell]

[0133] In each of Examples 13 to 15 and Comparative Examples 4 to 6, a full-cell having the following negative electrode layer, positive electrode layer, and electrolyte was fabricated.

[0134] A negative electrode layer was prepared, which contained a Si-based active material as a negative electrode active material, a polyamide-based resin as a binder, KB and VGCF as conductive materials in a ratio of 82:12:5:1 (wt%).

[0135] As the Si-based active materials in Examples 13 to 15 and Comparative Examples 4 to 6, the Si-based active materials shown in Table 3 were used.

[0136] The 1st diamond-type crystal Si, the 2nd diamond-type crystal Si (nanosized crystal Si), and the porous type-II Si clathrate (pcSi) shown in Table 3 are the same as those used in the half cell shown in Table 2.

[0137] A positive electrode layer was prepared, which contained NCM811 as a positive electrode active material, PVdF as a binder, and AB as a conductive material in a ratio of 90:5:5 (wt%).

[0138] As the separator, a three-layer separator of PE / PP / PE with micropores was used.

[0139] In Examples 13 to 15, the 3rd electrolyte (LiFSI:MeFSA = 1:4 (molar ratio)) used in Reference Experimental Example 3 was used.

[0140] In Comparative Examples 4 to 6, the conventional electrolyte used in Reference Experimental Example 5 was used.

[0141] The amount of electrolyte injected into the full cell was set to 700 μl.

[0142] [Calculation of the discharge capacity retention rate after 100 cycles based on the full cell]

[0143] In each of Examples 13 to 15 and Comparative Examples 4 to 6, 1200 mAh / g was defined as the charge capacity, and charge and discharge were performed on each full cell for 100 cycles in the temperature range of 25 °C and the cut-off voltage range of 2.5 V - 4.35 V, and the discharge capacity retention rate of each full cell was calculated. The 1st, 50th, and 100th cycles were charged and discharged under the condition of 0.1 C, and the 2nd to 49th and 51st to 99th cycles were charged and discharged under the condition of 1 C. The results are shown in Table 3.

[0144] Table 3

[0145] MeFSA / LiFSI Si-based Active Material Discharge Capacity Retention Rate (Molar Ratio) (％) Example 13 4 First Diamond-type Crystalline Si 34.1 Example 14 4 Second Diamond-type Crystalline Si 56.1 Example 15 4 Porous Type-II Si Inclusion 77.7 Comparative Example 4 - First Diamond-type Crystalline Si 55.7 Comparative Example 5 - Second Diamond-type Crystalline Si 43.6 Comparative Example 6 - Porous Type-II Si Inclusion 39

[0146] Figure 2 It is a graph showing the initial Coulomb efficiency, average Coulomb efficiency, and discharge capacity retention rate measured in Examples 7 to 9, 13 to 15, and Comparative Examples 1 to 6.

[0147] As shown in Table 3, it was confirmed that the discharge capacity retention rate after 100 cycles in the full cell was increased by about 2 times compared with the conventional electrolyte.

[0148] As Figure 2It can be confirmed that in the conventional electrolyte, the discharge capacity retention rate decreases due to the increase in the specific surface area of the Si-based active material. However, in the electrolyte of the present disclosure, the irreversible capacity decreases and the discharge capacity retention rate increases due to the increase in the specific surface area of the Si-based active material, indicating a tendency opposite to that of the conventional electrolyte.

Claims

1. A battery comprising a positive electrode layer, an electrolyte layer and a negative electrode layer in sequence, The electrolyte layer comprises dimethylaminosulfonyl fluoride (MeFSA) and lithium bis(fluorosulfonyl)imide (LiFSI). The negative electrode layer contains a Si-based active material as a negative electrode active material. 2 . The battery according to claim 1 , wherein the molar ratio of the LiFSI to the MeFSA is LiFSI:MeFSA=1:12 to 1:

3. The battery according to claim 1 , wherein the negative electrode active material is a porous silicon inclusion compound.

4. The battery according to claim 1, The negative electrode active material is a negative electrode active material particle, The D50 of the negative electrode active material particles is 0.7 μm or less.

5. The battery according to claim 1, The negative electrode active material is a negative electrode active material particle, The specific surface area of ​​the negative electrode active material particles is 25 to 60 m 2 / g.

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