All-solid-state battery

Abstract

An all-solid-state battery according to the present disclosure includes: a stack including a solid electrolyte layer, and a positive electrode layer and a negative electrode layer disposed such that the solid electrolyte layer is interposed between the positive electrode layer and the negative electrode layer; and a first encapsulation material layer and a second encapsulation material layer disposed such that the stack is interposed between the first encapsulation material layer and the second encapsulation material layer. The first layer of encapsulating material or the second layer of encapsulating material includes bentonite-based clay and ceramic glass that does not include lithium.

Description

Technical Field

[0001] The present disclosure relates to an all-solid-state battery. Background Art

[0002] Recently, devices using electric power as an energy source are increasing. As the application fields using electric power (such as smartphones, portable cameras, laptop personal computers (laptop PCs), electric vehicles, etc.) expand, attention to power storage devices using electrochemical devices is increasing. Among various electrochemical devices, rechargeable lithium batteries that can be charged and discharged and have a high operating voltage and a significantly high energy density are attracting great attention.

[0003] A rechargeable lithium battery is manufactured by coating materials capable of inserting and extracting lithium ions onto a positive electrode and a negative electrode, and then injecting a liquid electrolyte between the positive electrode and the negative electrode. Among them, according to the insertion and extraction of lithium ions at the positive electrode and the negative electrode, electric power is generated or consumed through an oxidation reaction / reduction reaction. These rechargeable lithium batteries should be substantially stable within the battery operating voltage range and have the performance of transporting ions at a sufficiently high speed.

[0004] When a liquid electrolyte (such as a non-aqueous electrolyte) is applied to these rechargeable lithium batteries, it has the advantages of high discharge capacity and high energy density. However, rechargeable lithium batteries have the following problems: it is difficult to achieve a high voltage, the electrolyte solution leaks, and there is a high risk of fire and explosion.

[0005] To solve this problem, a secondary all-solid-state battery using a solid electrolyte instead of a liquid electrolyte has been proposed as an alternative. Research on applying all-solid-state batteries to various fields is underway, and the demand for all-solid-state batteries with excellent insulation and moisture resistance is also increasing. Summary of the Invention Brief Description of the Drawings

[0007] Figure 1 is a perspective view schematically showing an all-solid-state battery according to an embodiment.

[0008] Figure 2 is a cross-sectional view of an all-solid-state battery according to an embodiment.

[0009] Figure 3 is a cross-sectional view of an all-solid-state battery in accordance with an all-solid-state battery according to another embodiment.

[0010] Figure 4 is a cross-sectional scanning electron microscope (SEM) photograph of ion-milled bentonite-based clay.

[0011] Figure 5 is a graph showing the cycle characteristics of the all-solid-state battery manufactured in Evaluation Example 1.

[0012] Figure 6 It is a graph for evaluating the cycle characteristics of the all-solid-state battery fabricated in the comparative example. Detailed implementation mode

[0013] The embodiment provides an all-solid-state battery having improved reliability due to excellent insulation and moisture resistance.

[0014] However, the objectives to be achieved by the embodiment are not limited to those mentioned above, but various extensions can be made without departing from the technical spirit of the embodiment.

[0015] The all-solid-state battery according to the embodiment includes: a stack including a solid electrolyte layer, a positive electrode layer, and a negative electrode layer, the positive electrode layer and the negative electrode layer being arranged such that the solid electrolyte layer is interposed between the positive electrode layer and the negative electrode layer; and a first encapsulation material layer and a second encapsulation material layer arranged such that the stack is interposed between the first encapsulation material layer and the second encapsulation material layer. The first encapsulation material layer or the second encapsulation material layer includes bentonite-based clay and a lithium-free ceramic glass.

[0016] Based on the total volume of the first encapsulation material layer or the second encapsulation material layer, the bentonite-based clay can be included in an amount of 10% to 70% by volume.

[0017] The average particle size of the bentonite-based clay can be 1 μm to 5 μm.

[0018] The lithium-free ceramic glass may include silicon (Si) oxide, boron (B) oxide, sodium (Na) oxide, barium (Ba) oxide, zinc (Zn) oxide, aluminum (Al) oxide, or a combination thereof.

[0019] The lithium-free ceramic glass may include SiO2, B2O3, Na2O, BaO5, ZnO, Al2O3, or a combination thereof.

[0020] The glass transition temperature (T g ) of the lithium-free ceramic glass can be 440 °C to 480 °C.

[0021] The volume ratio of the bentonite-based clay to the lithium-free ceramic glass can be 10:90 to 70:30.

[0022] The all-solid-state battery further includes: a first edge layer disposed on the same plane as the positive electrode layer; and a second edge layer disposed on the same plane as the negative electrode layer, and the first edge layer or the second edge layer may include the bentonite-based clay and the lithium-free ceramic glass.

[0023] Based on the total volume of the first edge layer or the second edge layer, the bentonite-based clay may be included in an amount of 10% to 70% by volume.

[0024] The average particle size of the bentonite-based clay in the first edge layer or the second edge layer may be 1 μm to 5 μm.

[0025] The lithium-free ceramic glass in the first edge layer or the second edge layer may include silicon (Si) oxide, boron (B) oxide, sodium (Na) oxide, barium (Ba) oxide, zinc (Zn) oxide, aluminum (Al) oxide, or a combination thereof.

[0026] The lithium-free ceramic glass in the first edge layer or the second edge layer may include SiO2, B2O3, Na2O, BaO5, ZnO, Al2O3, or a combination thereof.

[0027] The glass transition temperature (T g ) of the lithium-free ceramic glass in the first edge layer or the second edge layer may be 440 °C to 480 °C.

[0028] The volume ratio of the bentonite-based clay in the first edge layer or the second edge layer to the lithium-free ceramic glass in the first edge layer or the second edge layer may be 10:90 to 70:30.

[0029] A all-solid-state battery according to another embodiment includes: a stack including a plurality of solid electrolyte layers, a plurality of positive electrode layers, and a plurality of negative electrode layers, the plurality of positive electrode layers and the plurality of negative electrode layers being alternately arranged with the plurality of solid electrolyte layers interposed between the plurality of positive electrode layers and the plurality of negative electrode layers; a first encapsulation material layer and a second encapsulation material layer arranged with the stack interposed between the first encapsulation material layer and the second encapsulation material layer; and a first external electrode and a second external electrode respectively provided on one surface and the other surface of the stack and respectively connected to the positive electrode layer and the negative electrode layer. The first encapsulation material layer or the second encapsulation material layer includes a bentonite-based clay and a lithium-free ceramic glass.

[0030] The all-solid-state battery may further include a plurality of edge layers respectively provided on the same plane as the plurality of positive electrode layers and on the same plane as the plurality of negative electrode layers, wherein the edge layer includes the bentonite-based clay and the lithium-free ceramic glass.

[0031] The capacity retention rate of the all-solid-state battery after 5 cycles may be greater than or equal to 70%.

[0032] A all-solid-state battery according to another embodiment includes: a stack including a solid electrolyte layer, a positive electrode layer, and a negative electrode layer, the positive electrode layer and the negative electrode layer being arranged such that the solid electrolyte layer is interposed between the positive electrode layer and the negative electrode layer; a first edge layer disposed on the same plane as the positive electrode layer; a second edge layer disposed on the same plane as the negative electrode layer; a first encapsulation material layer and a second encapsulation material layer arranged such that the stack is interposed between the first encapsulation material layer and the second encapsulation material layer; and a first external electrode and a second external electrode respectively disposed on one surface and the other surface of the stack and respectively connected to the positive electrode layer and the negative electrode layer. The first edge layer or the second edge layer includes bentonite-based clay.

[0033] The first edge layer or the second edge layer may further include a lithium-free ceramic glass.

[0034] The solid electrolyte layer may include a material different from the first encapsulation material layer and the second encapsulation material layer.

[0035] The all-solid-state battery according to the embodiment has improved battery reliability due to excellent insulation characteristics and moisture resistance.

[0036] However, various beneficial advantages and effects of the present invention are not limited to the above, and will be more easily understood during the description of specific embodiments of the present invention.

[0037] Hereinafter, various embodiments of the present invention will be described in detail with reference to the drawings, so that those skilled in the art can easily implement the present invention. The drawings and the description are considered to be illustrative rather than restrictive in nature. Throughout the specification, the same reference numerals represent the same elements. In addition, the drawings are provided only to make the embodiments disclosed in this specification easily understood, and the drawings are not to be construed as limiting the spirit disclosed in this specification, and it should be understood that the present invention includes all variations, equivalents, and alternatives without departing from the scope and spirit of the present invention. Additionally, some of the components in the drawings are exaggerated, omitted, or shown schematically, and the dimensions of each component do not fully reflect the actual dimensions.

[0038] In addition, unless explicitly described to the contrary, the word "comprising" and variations such as "including" or "having" will be understood to imply including the stated elements without excluding any other elements.

[0039] Throughout the specification, the "stacking direction" refers to the direction in which the constituent elements are sequentially stacked or the "thickness direction" perpendicular to the major surface (principal surface) of the sheet-like constituent element, which corresponds to the T-axis direction in the drawings. Additionally, the "lateral direction" refers to the direction extending parallel to the major surface (principal surface) from the edge of the sheet-like constituent element or the "plane direction", which corresponds to the L-axis direction in the drawings.

[0040] Hereinafter, various embodiments and modifications will be described in detail with reference to the drawings.

[0041] Figure 1 is a perspective view schematically showing a all-solid-state battery according to an embodiment, Figure 2 is a cross-sectional view of the all-solid-state battery according to an embodiment, and Figure 3 is a cross-sectional view of the all-solid-state battery in accordance with an all-solid-state battery according to another embodiment. Hereinafter, with reference to Figures 1 to 3 the all-solid-state battery will be described in detail.

[0042] For example, the all-solid-state battery 100 may have a substantially hexahedral shape.

[0043] The all-solid-state battery 100 according to an embodiment includes: a stack 110 including a solid electrolyte layer 111 and a positive electrode layer 121 and a negative electrode layer 122, the positive electrode layer 121 and the negative electrode layer 122 being arranged such that the solid electrolyte layer 111 is interposed between the positive electrode layer 121 and the negative electrode layer 122; and a first encapsulation material layer 131 and a second encapsulation material layer 132, arranged such that the stack 110 is interposed between the first encapsulation material layer 131 and the second encapsulation material layer 132.

[0044] The first encapsulation material layer 131 or the second encapsulation material layer 132 includes bentonite-based clay and a ceramic glass that does not contain lithium.

[0045] The all-solid-state battery 100 may further include a first edge layer 141 and a second edge layer 142, the first edge layer 141 being provided on the same plane as the positive electrode layer 121, and the second edge layer 142 being provided on the same plane as the negative electrode layer 122.

[0046] The first edge layer 141 or the second edge layer 142 includes bentonite-based clay and a ceramic glass that does not contain lithium.

[0047] For example, the first encapsulation material layer, the second encapsulation material layer, the first edge layer, the second edge layer, or a combination thereof includes bentonite-based clay and a ceramic glass that does not contain lithium.

[0048] Alternatively, the first encapsulation material layer and the second encapsulation material layer include bentonite-based clay and a ceramic glass that does not contain lithium, or the first edge layer and the second edge layer include bentonite-based clay and a ceramic glass that does not contain lithium.

[0049] In addition, the first encapsulation material layer, the second encapsulation material layer, the first edge layer, and the second edge layer include bentonite-based clay and include a lithium-free ceramic glass.

[0050] In this document, the bentonite-based clay and the lithium-free ceramic glass included in the encapsulation material layer or the edge layer can be the same material. Hereinafter, the bentonite-based clay and the lithium-free ceramic glass included in the encapsulation material layer or the edge layer will be described in more detail.

[0051] Figure 4 is a cross-sectional scanning electron microscope (SEM) photograph of ion-milled bentonite-based clay. Refer to Figure 4 , the bentonite-based clay (a clay mineral formed by sedimentary rock action, where volcanic ash is compacted by seawater and recrystallized) consists of nanoscale particles and has excellent cation exchange adsorption properties. Specifically, the bentonite-based clay has excellent hygroscopicity and can expand up to 12 times its original volume at most. Such bentonite-based clay can be included in the encapsulation material layer or the edge layer to prevent the intrusion of external moisture, etc., and the effects of physical and chemical shocks from the outside, thereby realizing an all-solid-state battery with excellent moisture-proof function.

[0052] For example, the types of bentonite-based clay include Na-type bentonite containing a large amount of Na + ions, Ca-type bentonite containing a large amount of Ca 2+ ions, bentonite obtained by artificially activating Ca-type bentonite into Na-type bentonite by adding some wt% sodium carbonate to Ca-type bentonite, etc.

[0053] The average particle size of the bentonite-based clay can be 1 μm to 5 μm, for example, 1 μm to 3 μm or 1 μm to 2.5 μm. When the average particle size of the bentonite-based clay is within this range, the particles can be uniformly dispersed, thereby effectively exhibiting the moisture-proof function.

[0054] Based on the total volume of the first encapsulation material layer or the second encapsulation material layer, the bentonite-based clay can be included in an amount of 10 vol% to 70 vol%, for example, 20 vol% to 60 vol% or 40 vol% to 60 vol%.

[0055] Based on the total volume of the first edge layer or the second edge layer, the bentonite-based clay can be included in an amount of 10 vol% to 70 vol%, for example, 20 vol% to 60 vol% or 40 vol% to 60 vol%.

[0056] When the bentonite-based clay is included within the said volume range, an excellent moisture-proof function can be achieved without mechanical degradation of the encapsulation material layer or the edge layer.

[0057] In the encapsulation material layer or the edge layer, an insulating material used in the art may also be included to impart an additional insulating function. Examples of the insulating material may include aluminum oxide (Al2O3), aluminum nitride (AlN), beryllium oxide (BeO), boron nitride (BN), silicon (Si), silicon carbide (SiC), silicon dioxide (SiO2), silicon nitride (Si3N4), gallium arsenide (GaAs), gallium nitride (GaN), barium titanate (BaTiO3), zirconium dioxide (ZrO2), their mixtures, oxides and / or nitrides of these materials, or any other suitable ceramic material, but not limited thereto.

[0058] The ceramic glass that does not contain lithium (Li) has low ionic conductivity and low electronic conductivity and prevents the leakage of ions and electrons in the all-solid-state battery to prevent the deterioration of the battery capacity.

[0059] The ceramic glass that does not contain lithium may include silicon (Si) oxide, boron (B) oxide, sodium (Na) oxide, barium (Ba) oxide, zinc (Zn) oxide, aluminum (Al) oxide, or a combination thereof.

[0060] The ceramic glass that does not contain lithium may include SiO2, B2O3, Na2O, BaO5, ZnO, Al2O3, or a combination thereof.

[0061] The glass transition temperature (T g ) of the ceramic glass that does not contain lithium may be 440 °C to 480 °C. When the glass transition temperature (T g ) of the ceramic glass that does not contain lithium is within this range, since the glass transition temperature (T g ) is similar to the baking temperature of the solid electrolyte, the internal and external materials of the all-solid-state battery have similar baking temperatures and shrinkages during the baking process, thus preventing thermal deformation.

[0062] Based on the total volume of the first encapsulation material layer or the second encapsulation material layer, the ceramic glass that does not contain lithium may be included in an amount of 30 vol% to 70 vol%, for example, the ceramic glass that does not contain lithium may be included in an amount of 30 vol% to 60 vol%.

[0063] When the amount of the ceramic glass that does not contain lithium included is less than 30 vol% based on the total amount of the first encapsulation material layer or the second encapsulation material layer, it may be difficult for the all-solid-state battery to maintain its shape, and when the amount of the ceramic glass that does not contain lithium included is greater than 70 vol%, there is a disadvantage of deteriorating the moisture-proof effect.

[0064] It may include a bentonite-based clay and a lithium-free ceramic glass in a volume ratio of 10:90 to 70:30. When the bentonite-based clay is included in an excessive amount, it may be difficult for the all-solid-state battery to maintain its shape, and there is a disadvantage of deteriorating moisture-proof effect.

[0065] In an embodiment, the solid electrolyte layer 111 may include an inorganic solid electrolyte, and the inorganic solid electrolyte includes an oxide-based solid electrolyte, a sulfide-based solid electrolyte, or a combination thereof.

[0066] The oxide-based solid electrolyte may be a garnet-type electrolyte, a sodium superionic conductor (NASICON)-type electrolyte, a lithium superionic conductor (LISICON)-type electrolyte, a perovskite-type electrolyte, a lithium phosphorus oxynitride (LiPON)-type electrolyte, or an amorphous (glass) electrolyte.

[0067] The garnet-based solid electrolyte may include lithium lanthanum zirconium oxide (LLZO) represented by Li a La b Zr c O 12 (such as Li7La3Zr2O 12 ), and the sodium superionic conductor (NASICON)-based solid electrolyte may include lithium aluminum titanium phosphate (LATP) (Li 1+ x Al x M 2-x (PO4)3 (LAMP) (0 < x < 2, M is Zr, Ti or Ge)-type compound (Li 1+x Al x Ti 2-x (PO4)3 (0 < x < 1)), lithium aluminum germanium phosphate (LAGP) represented by Li 1+x Al x Ge 2-x (PO4)3 (0 < x < 1) (such as Li 1.3 Al 0.3 Ti 1.7 (PO4)3 with excessive lithium introduced) and / or lithium zirconium phosphate (LZP) (LiZr2(PO4)3).

[0068] In addition, the lithium superionic conductor (LISICON)-based solid electrolyte may include a solid solution oxide represented by xLi3AO4-(1-x)Li4BO4 (A: P, As, V, and B: Si, Ge, Ti), such as Li4Zn(GeO4)4, Li 10 GeP2O 12 (LGPO), Li 3.5 Si 0.5 P 0.5O4 or Li 10.42 Si(Ge) 1.5 P 1.5 Cl 0.08 O 11.92 , or composed of Li 4-x M 1-y M' y Solid solution sulfides represented by S4 (where M: Si, Ge, and M' is P, Al, Zn, Ga), such as Li2S - P2S5, Li2S - SiS2, Li2S - SiS2 - P2S5, or Li2S - GeS2.

[0069] Perovskite - based solid electrolytes may include lithium lanthanum titanate (LLTO) represented by Li 3x La 2 / 3-x □ 1 / 3-2x TiO3 (0 < x < 0.16, □: vacancy), such as Li 1 / 8 La 5 / 8 TiO3. Lithium phosphorus oxynitride (LiPON) - based solid electrolytes may include lithium phosphorus oxynitrides, such as Li 2.8 PO 3.3 N 0.46 .

[0070] Amorphous electrolytes may include Li2O - B2O3 - SiO2 (LBSO), Li2O - B2O3 - P2O5, Li3BO3 - Li2SO4, or Li3BO3 - Li2CO3.

[0071] Sulfide - based solid electrolytes may include sulfur atoms among the electrolyte components, which are not limited to specific components, and may include one or more of crystalline solid electrolytes, amorphous solid electrolytes (vitreous solid electrolytes), or glass - ceramic solid electrolytes.

[0072] For example, sulfide - based solid electrolytes may include LPS - type sulfides containing sulfur and phosphorus (e.g., Li2S - P2S5), or may include thio - LISICON - based compounds Li 4-x Ge 1-x P x S4 (x is 0.1 to 2, or x is 3 / 4, or 2 / 3), Li 10±1 MP2X 12 (where M is Ge, Si, Sn, or Al, and X is S or Se), Li 3.833 Sn 0.833 As 0.166 S4, Li4SnS4, Li 3.25 Ge 0.25 P 0.75S4, Li2S-P2S5, B2S3-Li2S, xLi2S-100-xP2S5 (where x ranges from 70 to 80), Li2S-SiS2-Li3N, Li2S-P2S5-LiI, Li2S-SiS2-LiI, Li2S-B2S3-LiI, Li 10 SnP2S 12 or Li 3.25 Ge 0.25 P 0.75 S4.

[0073] The solid electrolyte may have an ionic conductivity greater than or equal to 1×10 -3 S / cm. The ionic conductivity can be measured at a temperature of 25°C. The ionic conductivity may be greater than or equal to 1×10 -3 S / cm, 2×10 -3 S / cm, greater than or equal to 3×10 -3 S / cm, greater than or equal to 4×10 -3 S / cm, or greater than or equal to 5×10 -3 S / cm, and there is no particular limitation on the upper limit of the ionic conductivity. When a solid electrolyte satisfying the range of the ionic conductivity is used, the all-solid-state battery 100 can exhibit high output.

[0074] In an embodiment, the positive electrode layer 121 of the all-solid-state battery 100 may include a positive electrode active material and a conductive material. In an embodiment, the positive electrode layer 121 of the all-solid-state battery may be an integrated positive electrode layer 121 in which the positive electrode active material and the conductive material are mixed and disposed.

[0075] The positive electrode active material may include, for example, a compound represented by the following chemical formula: Li a A 1-b M b D2 (where 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5); Li a E 1-b M b O 2-c D c (where 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE 2- b M b O 4-c D c (where 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiaNi 1-b-c Co b M c D α (where 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li aNi 1-b-c Co b M c O 2-α X α (where 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Co b M c O 2-α X2 (where 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b M c D α (where 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Mn b M c O 2-α X α (where 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b M c O 2-α X2 (where 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni b E c G d O2 (where 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d G e O2 (where 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li a NiG b O2 (where 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (where 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (where 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Lia Mn2G b O4 (where 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O2; LiRO2; LiNiVO4; Li (3-f) J2(PO4)3 (0 ≤ f ≤ 2) Li (3-f) Fe2(PO4)3 (where 0 ≤ f ≤ 2) and LiFePO4, where in the above chemical formulas, A is Ni, Co or Mn; M is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V or a rare earth element; D is O, F, S or P; E is Co or Mn; X is F, S or P; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr or V; Q is Ti, Mo or Mn; R is Cr, V, Fe, Sc or Y; and J is V, Cr, Mn, Co, Ni or Cu.

[0076] The positive electrode active material may also be LiCoO2, LiMn x O 2x (where x = 1 or 2), LiNi 1-x Mn x O 2x (where 0 < x < 1), LiNi 1-x-y Co x Mn y O2 (where 0 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.5), LiFePO4, TiS2, FeS2, TiS3 or FeS3, but not limited thereto.

[0077] The conductive agent is not particularly limited as long as its conductivity does not cause chemical changes in the all-solid-state battery 100. Examples of the conductive agent may include: graphite such as natural graphite and artificial graphite; carbon-based substances 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; carbon fluorides; metal components such as lithium (Li), tin (Sn), aluminum (Al), nickel (Ni), copper (Cu), etc.; their oxides, nitrides or sulfides; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive materials such as polyphenylene derivatives.

[0078] In the examples, the positive electrode layer 121 of the all-solid-state battery may further include a solid electrolyte component. The solid electrolyte component may use one or more of the above components and can be used as an ion conduction channel in the positive electrode layer. Thus, the interfacial resistance can be reduced.

[0079] The method for forming the positive electrode layer 121 is not particularly limited, but may include, for example: preparing a slurry by mixing a positive electrode active material, a conductive material (optionally further including a solid electrolyte layer), a binder, etc., coating such a slurry on a separate support, and curing it to form the positive electrode layer 121.

[0080] In an embodiment, the negative electrode layer 122 of the all-solid-state battery 100 may include a negative electrode active material and a conductive material. In one embodiment, the negative electrode layer 122 of the all-solid-state battery may be an integrated negative electrode layer 122 in which the negative electrode active material and the conductive material are mixed and disposed.

[0081] The negative electrode layer may include commonly used negative electrode active materials. The negative electrode active material may be a carbon-based material, silicon, silicon oxide, silicon-based alloy, silicon-carbon-based material composite, tin, tin-based alloy, tin-carbon composite, metal oxide, or a combination thereof, and may include lithium metal and / or lithium metal alloy.

[0082] The lithium metal alloy may include lithium and a metal / metalloid capable of alloying with lithium. For example, the metal / metalloid capable of alloying with lithium may include Si, Sn, Al, Ge, Pb, Bi, Sb, Si-Y alloy (where Y is an alkali metal, alkaline earth metal, Group 13 to Group 16 element, transition metal, rare earth element, or a combination thereof, and does not include Si), Sn-Y alloy (where Y is an alkali metal, alkaline earth metal, Group 13 to Group 16 element, transition metal, such as lithium titanate (Li4Ti5O 12 ), transition metal oxide, rare earth element, or a combination thereof, and does not include Sn) or M n O x (0 < x ≤ 2). The element Y may be Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof.

[0083] In addition, the oxide of the metal / metalloid capable of alloying with lithium may be lithium titanate, vanadium oxide, lithium vanadium oxide, SnO2, SiO x (0 < x < 2), etc. For example, the negative electrode active material may include one or more elements selected from the elements of Group 13 to Group 16 of the periodic table. For example, the negative electrode active material may include one or more elements selected from the group consisting of Si, Ge, and Sn.

[0084] The carbon-based material can be crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon may include graphite, such as natural graphite or artificial graphite in irregular forms, plate forms, flake forms, spherical forms, or fiber forms. Additionally, the amorphous carbon may include soft carbon (low-temperature calcined carbon) or hard carbon, mesophase pitch carbonization products, calcined coke, graphene, carbon black, fullerene soot, carbon nanotubes, carbon fibers, etc., but is not limited thereto.

[0085] Silicon can be selected from Si, SiO x (0 < x < 2, for example, 0.5 to 1.5), Sn, SnO2, silicon-containing metal alloys, and mixtures thereof. For example, the silicon-containing metal alloy may include one or more of Al, Sn, Ag, Fe, Bi, Mg, Zn, In, Ge, Pb, and Ti and silicon.

[0086] In an embodiment, the negative electrode layer 122 of the all-solid-state battery 100 can use the same conductive material as in the positive electrode layer 121. Except for using the negative electrode active material instead of the positive electrode active material in the manufacturing process of the above positive electrode, the negative electrode layer 122 can be manufactured according to an almost identical method.

[0087] Referring to Figure 3 , the all-solid-state battery 100 according to another embodiment includes: a stack 100 including a plurality of solid electrolyte layers 111, a plurality of positive electrode layers 121, and a plurality of negative electrode layers 122, the plurality of positive electrode layers 121 and the plurality of negative electrode layers 122 being alternately arranged and the plurality of solid electrolyte layers 111 being interposed between the positive electrode layer 121 and the negative electrode layer 122; a first encapsulation material layer 131 and a second encapsulation material layer 132 arranged such that the stack is interposed between the first encapsulation material layer 131 and the second encapsulation material layer 132; and a first external electrode 151 and a second external electrode 152 respectively provided on one surface and the other surface of the stack 110 and respectively connected to the positive electrode layer 121 and the negative electrode layer 122. The first encapsulation material layer 131 or the second encapsulation material layer 132 includes bentonite-based clay and lithium-free ceramic glass.

[0088] The all-solid-state battery may further include a plurality of edge layers 141 and 142, the plurality of edge layers 141 being provided on the same plane as the plurality of positive electrode layers 121, and the plurality of edge layers 142 being provided on the same plane as the plurality of negative electrode layers 122.

[0089] The edge layers 141 and 142 may include bentonite-based clay and lithium-free ceramic glass.

[0090] The first external electrode 151 and the second external electrode 152 may include a conductive metal and glass.

[0091] For example, the conductive metal may include copper (Cu), nickel (Ni), tin (Sn), palladium (Pd), platinum (Pt), gold (Au), silver (Ag), tungsten (W), titanium (Ti), lead (Pb), or an alloy thereof.

[0092] The glass may have a composition in which oxides are mixed. For example, the glass may include silicon oxide, boron oxide, aluminum oxide, transition metal oxide, alkali metal oxide, alkaline earth metal oxide, or a combination thereof. In the present disclosure, the transition metal may be selected from zinc (Zn), titanium (Ti), copper (Cu), vanadium (V), manganese (Mn), iron (Fe), and nickel (Ni), the alkali metal may be selected from lithium (Li), sodium (Na), and potassium (K), and the alkaline earth metal may be selected from magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).

[0093] The method for forming the first external electrode and the second external electrode is not particularly limited. For example, the method may include dipping the unit stack in a conductive paste including a conductive metal and glass, or screen printing or gravure printing the conductive paste on the surface of the unit stack.

[0094] In addition, various methods such as coating a conductive paste on the surface of the unit stack or transferring a dry film obtained by drying the conductive paste to the unit stack may be used.

[0095] The all-solid-state battery according to the embodiment has excellent insulation and moisture-proof functions, and thus exhibits a capacity retention rate of greater than or equal to 70% after 5 cycles. Therefore, the all-solid-state battery can exhibit excellent reliability.

[0096] Hereinafter, specific embodiments of the invention are presented. However, the following embodiments are intended to specifically illustrate or explain the invention, and the scope of the invention should not be limited thereto.

[0097] [Example 1] The positive electrode active material (LiCoO2 (LCO)) and the solid electrolyte (Li2O-B2O3-SiO2 (hereinafter, LBSO)) were mixed at a volume ratio of 5:5 and then screen printed to form a positive electrode layer having a thickness of 12 μm. The negative electrode active material (graphite of 2 μm) and the solid electrolyte (LBSO) were mixed at a volume ratio of 5:5 and then screen printed to form a negative electrode layer having a thickness of 8 μm. The solid electrolyte of LBSO was molded to form a solid electrolyte layer having a thickness of 25 μm. 50% by volume of bentonite-based clay of 2 μm and 50% by volume of lithium-free ceramic glass (SiO2-B2O3-Na2O-BaO5-ZnO-Al2O3) were mixed to form a first encapsulation material layer and a second encapsulation material layer. As Figure 2 shown, each layer prepared above was stacked to fabricate an all-solid-state battery cell.

[0098] [Example 2] A all-solid-state battery cell is manufactured in the same manner as in Example 1, except that the first edge layer and the second edge layer are formed in the same configuration as the first encapsulation material layer and the second encapsulation material layer.

[0099] [Comparative Example] A all-solid-state battery cell is manufactured in the same manner as in Example 1, except that the first encapsulation material layer and the second encapsulation material layer are made into 20 sheets of a solid electrolyte having 100% by volume of LBSO.

[0100] [Experimental Example] (Evaluation of Cycling Characteristics) The cycling characteristics of the all-solid-state battery cells according to Example 1 and Example 2 and the Comparative Example are evaluated as follows.

[0101] Under the conditions of 90 wt% and 60 °C, the all-solid-state battery cell is charged to a maximum voltage of 4.3 V at a constant current of 0.5 C, and then discharged to a cut-off voltage of 1.0 V at a constant current of 0.5 C, and this charge and discharge cycle is repeated 5 times. Then, the ratio of the discharge capacity in the 5th cycle to the discharge capacity in the 1st cycle is obtained as the capacity retention rate. The capacity retention rate is a parameter representing the cycling characteristics, and the larger the capacity retention rate, the more excellent the cycling characteristics. The results of the cycling characteristics of the examples and the comparative example are shown in Figure 5 and Figure 6 .

[0102] Refer to Figure 5 (Example 1). Since bentonite-based clay and lithium-free ceramic glass are included in the first encapsulation material layer and the second encapsulation material layer, the capacity after 5 cycles can maintain 70% of the initial capacity, which confirms the very excellent cycling reliability characteristics of the battery cell.

[0103] In addition, even when both bentonite-based clay and lithium-free ceramic glass are included in the first encapsulation material layer, the second encapsulation material layer, the first edge layer, and the second edge layer, the capacity after 5 cycles can still maintain 70% of the initial capacity, which confirms the very excellent cycling reliability characteristics of the battery cell.

[0104] Refer to Figure 6 (Comparative Example). Since bentonite-based clay and lithium-free ceramic glass are not included in the encapsulation material layer, the cycling reliability characteristics of the battery cell are very poor.

[0105] Although the present invention has been described in connection with the content of the embodiments that are currently considered to be practical, it will be understood that the present invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0106] Industrial applicability The present disclosure relates to an all-solid-state battery having excellent insulation and moisture-proof functions and thus improved reliability, which can be used in various electrochemical devices and electronic devices.

[0107] <Description of reference numerals> 100: All-solid-state battery 110: Stack 111: Solid electrolyte layer 121: Positive electrode layer 122: Negative electrode layer 131: First encapsulation material layer 132: Second encapsulation material layer 141: First edge layer 142: Second edge layer 151: First external electrode 152: Second external electrode

Claims

1. A all - solid - state battery, comprising: A stack body, including a solid electrolyte layer, a positive electrode layer, and a negative electrode layer, wherein the positive electrode layer and the negative electrode layer are arranged such that the solid electrolyte layer is interposed between the positive electrode layer and the negative electrode layer; And A first encapsulation material layer and a second encapsulation material layer, arranged such that the stack body is interposed between the first encapsulation material layer and the second encapsulation material layer, wherein, the first encapsulation material layer or the second encapsulation material layer includes bentonite - based clay and a lithium - free ceramic glass.

2. The all - solid - state battery according to claim 1, wherein, Based on the total volume of the first encapsulation material layer or the second encapsulation material layer, the bentonite - based clay is included in an amount of 10% to 70% by volume.

3. The all - solid - state battery according to claim 1, wherein, The average particle size of the bentonite - based clay is 1 μm to 5 μm.

4. The all - solid - state battery according to claim 1, wherein, The lithium - free ceramic glass includes silicon (Si) oxide, boron (B) oxide, sodium (Na) oxide, barium (Ba) oxide, zinc (Zn) oxide, aluminum (Al) oxide, or a combination thereof.

5. The all - solid - state battery according to claim 1, wherein, The lithium - free ceramic glass includes SiO2, B2O3, Na2O, BaO5, ZnO, Al2O3, or a combination thereof.

6. The all - solid - state battery according to claim 1, wherein, The glass transition temperature (T g ) of the lithium-free ceramic glass is 440 °C to 480 °C.

7. The all - solid - state battery according to claim 1, wherein, The volume ratio of the bentonite - based clay to the lithium - free ceramic glass is 10:90 to 70:

30.

8. The all - solid - state battery according to claim 1, wherein, The all - solid - state battery further includes: a first edge layer disposed on the same plane as the positive electrode layer; and a second edge layer disposed on the same plane as the negative electrode layer, wherein, the first edge layer or the second edge layer includes the bentonite - based clay and the lithium - free ceramic glass.

9. The all - solid - state battery according to claim 8, wherein, Based on the total volume of the first edge layer or the second edge layer, the bentonite - based clay is included in an amount of 10% to 70% by volume.

10. The all - solid - state battery according to claim 8, wherein, The average particle size of the bentonite - based clay in the first edge layer or the second edge layer is 1 μm to 5 μm.

11. The all - solid - state battery according to claim 8, wherein, The lithium - free ceramic glass in the first edge layer or the second edge layer includes silicon (Si) oxide, boron (B) oxide, sodium (Na) oxide, barium (Ba) oxide, zinc (Zn) oxide, aluminum (Al) oxide, or a combination thereof.

12. The all - solid - state battery according to claim 8, wherein, The lithium - free ceramic glass in the first edge layer or the second edge layer includes SiO2, B2O3, Na2O, BaO5, ZnO, Al2O3, or a combination thereof.

13. The all - solid - state battery according to claim 8, wherein, The glass transition temperature (T g ) of the lithium-free ceramic glass of the first edge layer or the second edge layer is 440 °C to 480 °C.

14. The all-solid-state battery according to claim 8, wherein, the volume ratio of the bentonite-based clay in the first edge layer or the second edge layer to the lithium-free ceramic glass in the first edge layer or the second edge layer is 10:90 to 70:

30.

15. The all-solid-state battery according to claim 1, wherein, the capacity retention rate of the all-solid-state battery after 5 cycles is greater than or equal to 70%.

16. An all-solid-state battery, comprising: a stack including a plurality of solid electrolyte layers, a plurality of positive electrode layers, and a plurality of negative electrode layers, wherein the plurality of positive electrode layers and the plurality of negative electrode layers are alternately arranged with the plurality of solid electrolyte layers interposed between the plurality of positive electrode layers and the plurality of negative electrode layers; a first encapsulation material layer and a second encapsulation material layer arranged such that the stack is interposed between the first encapsulation material layer and the second encapsulation material layer; and a first external electrode and a second external electrode respectively provided on one surface and the other surface of the stack and respectively connected to the positive electrode layer and the negative electrode layer, wherein the first encapsulation material layer or the second encapsulation material layer includes bentonite-based clay and lithium-free ceramic glass.

17. The all-solid-state battery according to claim 16, wherein, the all-solid-state battery further includes a plurality of edge layers respectively provided on the same plane as the plurality of positive electrode layers and on the same plane as the plurality of negative electrode layers, and the edge layer includes the bentonite-based clay and the lithium-free ceramic glass.

18. The all-solid-state battery according to claim 16, wherein, the capacity retention rate of the all-solid-state battery after 5 cycles is greater than or equal to 70%.

19. An all-solid-state battery, comprising: a stack including a solid electrolyte layer, a positive electrode layer, and a negative electrode layer, wherein the positive electrode layer and the negative electrode layer are arranged such that the solid electrolyte layer is interposed between the positive electrode layer and the negative electrode layer; a first edge layer provided on the same plane as the positive electrode layer; a second edge layer provided on the same plane as the negative electrode layer; a first encapsulation material layer and a second encapsulation material layer arranged such that the stack is interposed between the first encapsulation material layer and the second encapsulation material layer; and a first external electrode and a second external electrode respectively provided on one surface and the other surface of the stack and respectively connected to the positive electrode layer and the negative electrode layer, wherein the first edge layer or the second edge layer includes bentonite-based clay.

20. The all-solid-state battery according to claim 19, wherein, the bentonite-based clay is included in an amount of 10% to 70% by volume based on the total volume of the first edge layer or the second edge layer.

21. The all-solid-state battery according to claim 19, wherein, the average particle size of the bentonite-based clay is 1 μm to 5 μm.

22. The all-solid-state battery according to claim 19, wherein, the first edge layer or the second edge layer further includes lithium-free ceramic glass.

23. The all-solid-state battery according to claim 22, wherein, The ceramic glass without lithium includes silicon (Si) oxide, boron (B) oxide, sodium (Na) oxide, barium (Ba) oxide, zinc (Zn) oxide, aluminum (Al) oxide, or a combination thereof.

24. The all-solid-state battery according to claim 22, wherein the ceramic glass without lithium includes SiO2, B2O3, Na2O, BaO5, ZnO, Al2O3, or a combination thereof.

25. The all-solid-state battery according to claim 22, wherein The glass transition temperature (T g ) of the lithium-free ceramic glass is 440°C to 480°C.

26. The all-solid-state battery according to claim 22, wherein the volume ratio of the bentonite-based clay to the ceramic glass without lithium is 10:90 to 70:

30.

27. The all-solid-state battery according to claim 19, wherein the solid electrolyte layer includes a material different from the first encapsulation material layer and the second encapsulation material layer.

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