All-solid-state battery including composite electrode, battery pack and device including the battery

Abstract

The present invention relates to an all-solid-state battery including an electrode assembly and a solid electrolyte, wherein the electrode assembly has a stacked structure of plate-shaped electrodes; the electrodes include a first electrode having the ability to generate relatively high heat and a second electrode having the ability to generate relatively low heat; and the first electrode is placed at the center of the electrode assembly. The present invention increases the temperature of the battery without adding any additional components to the battery, thereby providing an all-solid-state battery with improved performance.

Description

Technical Field

[0001] The present invention relates to an all-solid-state battery including a composite electrode, which can compensate for the low electrochemical performance of the all-solid-state battery by arranging an electrode that generates a large amount of heat at the center of an electrode assembly. Background Art

[0002] As mobile electronic devices including mobile phones are required to have various functions, the demand for lithium secondary batteries having high energy density has increased.

[0003] In addition, in order to use lithium secondary batteries in power storage devices and electric vehicles requiring high capacity and high output energy, research on safety improvement and high voltage of lithium secondary batteries has been actively conducted.

[0004] Compared with lithium manganese batteries or nickel cadmium batteries, lithium ion secondary batteries, which are one type of lithium secondary batteries, have advantages of high energy density, low self-discharge rate and long life. However, the disadvantage of lithium ion secondary batteries has been pointed out as stability problems caused by overheating.

[0005] In order to overcome the problems of lithium-ion secondary batteries, all-solid-state batteries have been proposed as an alternative. The all-solid-state battery may include an electrolyte layer containing a solid electrolyte and a positive electrode layer and a negative electrode layer including a solid electrolyte formed on both sides of the electrolyte layer, and the all-solid-state battery may be configured to have a structure in which a current collector can be connected to each of the positive electrode layer and the negative electrode layer.

[0006] When compared with conventional lithium-ion secondary batteries, all-solid-state batteries have superior safety than conventional lithium-ion secondary batteries. However, due to the low ion conductivity of the solid electrolyte, all-solid-state batteries have problems with poor performance such as capacity and output.

[0007] In order to solve the above-mentioned problems, a technology utilizing the property of an all-solid-state battery that ion conductivity greatly increases when the temperature rises has been proposed as an alternative.

[0008] In particular, Patent Document 1 discloses a secondary battery in which a heat generating unit insulated from an electrode is provided on a current collector, and the secondary battery is provided with a temperature control unit and a current carrying control unit for detecting the temperature inside the battery and controlling the current entering the heat generating unit.

[0009] When a separate heat generating unit is provided as in Patent Document 1, there are problems in that energy density is reduced due to an increase in the overall size of the battery, and energy is wasted when the external heat generating unit requires separate power.

[0010] Patent document 2 discloses a non-aqueous electrolyte secondary battery capable of suppressing heat generation in the battery, wherein a PTC layer is arranged between the positive electrode active material layer and the positive electrode current collector, wherein the PTC layer is composed of a collection of conductive particles, thereby preventing the flow of current under conditions of temperature rise due to overcharging of the battery.

[0011] Patent document 3 discloses a non-aqueous secondary battery having a structure in which a conductive layer covers an electrode current collector, the conductive layer including a crystalline thermoplastic resin, a conductive material and a binder, the crystalline thermoplastic resin having the function of a constant temperature coefficient resistor whose resistance value increases as the temperature rises.

[0012] Patent Document 2 and Patent Document 3 merely disclose a technique for preventing heat generation by blocking current when the battery temperature rises, but fail to provide a method for maintaining the heat generation state of the battery.

[0013] Patent Document 4 relates to a battery cell in which a heating element for radiating resistance heat by mutual interaction inside the battery is provided at one or two interfaces of a unit cell located at the center of an electrode assembly.

[0014] Patent Document 4 discloses a battery cell including a heating element that increases the internal temperature of the battery. However, since the thickness of the battery cell including the heating element is relatively increased or the thickness of the electrode assembly is relatively decreased, there is a problem of reduced energy density.

[0015] Therefore, there is a great need for a technology that can improve battery function by increasing the battery temperature within the all-solid-state battery while preventing a decrease in energy density in the all-solid-state battery without increasing the volume of the battery cell and adding a separate external power source.

[0016] (Prior art literature)

[0017] (Patent Document 1) Japanese Patent No. 5314872 (July 12, 2013)

[0018] (Patent Document 2) Japanese Patent Application Publication No. 2009-176599 (August 6, 2009)

[0019] (Patent Document 3) Japanese Patent Application Publication No. 2001-357854 (December 26, 2001)

[0020] (Patent Document 4) Korean Patent No. 1760647 (July 18, 2017) Summary of the invention

[0021] Technical issues

[0022] The present invention is made in view of the above problems, and an object of the present invention is to provide an all-solid-state battery, which has the characteristics of high capacity and high energy density by applying electrodes that generate a large amount of heat to part of the electrodes of the electrode assembly so that the battery temperature itself increases due to the heat generated under the normal operating environment of the battery.

[0023] Technical Solution

[0024] In order to achieve the above objectives, the present invention provides an all-solid-state battery comprising an electrode assembly and a solid electrolyte, wherein the electrode assembly comprises a structure with stacked plate electrodes; and the electrodes comprise a first electrode that generates relatively high heat and a second electrode that generates relatively low heat, wherein the first electrode is arranged at the center of the electrode assembly.

[0025] In a specific example, the electrode assembly may be a stacked electrode assembly; and the first electrode and the second electrode may have the same active material composition, wherein the content ratio of the solid electrolyte in the first electrode may be higher than the content ratio of the solid electrolyte in the second electrode.

[0026] Alternatively, the electrode assembly may be a laminated / stacked electrode assembly or a stacked / folded electrode assembly including a plurality of unit cells, wherein the plurality of unit cells are configured to have a first unit cell including the first electrode and a second unit cell including the second electrode. The first electrode and the second electrode may have the same composition of active material, wherein the content ratio of the solid electrolyte in the first electrode may be higher than the content ratio of the solid electrolyte in the second electrode.

[0027] In another specific example, the electrode assembly may be a stacked electrode assembly; and the active material of the first electrode and the active material of the second electrode may be a negative electrode active material that generates relatively high heat and a negative electrode active material that generates relatively low heat selected from hard carbon, soft carbon, artificial graphite, natural graphite coated with artificial graphite, natural graphite and silicon oxide.

[0028] Alternatively, the electrode assembly may be a laminated / stacked electrode assembly or a stacked / folded electrode assembly including a plurality of unit cells; the plurality of unit cells may be configured to have a first unit cell including the first electrode and a second unit cell including the second electrode; and the active material of the first electrode and the active material of the second electrode may be a negative electrode active material that generates relatively high heat and a negative electrode active material that generates relatively low heat selected from hard carbon, soft carbon, artificial graphite, natural graphite coated with artificial graphite, natural graphite and silicon oxide.

[0029] In addition, each of the first unit cell and the second unit cell may include a uniform active material.

[0030] The electrode may be a positive electrode or a negative electrode, or both a positive electrode and a negative electrode.

[0031] The solid electrolyte may be a sulfide solid electrolyte, an oxide solid electrolyte or a polymer solid electrolyte.

[0032] The temperature of the first electrode may be transferred to the second electrode to increase the internal temperature of the battery.

[0033] The all-solid-state battery may have a larger capacity at sub-zero temperatures than an all-solid-state battery composed of a single electrode and having the same capacity at room temperature.

[0034] The present invention provides a battery pack including an all-solid-state battery and a device including the battery pack. The device may be any one selected from the group consisting of a mobile electronic device, a wearable electronic device, a tablet computer, a laptop computer, an electric vehicle, and a power storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a side view showing a stacked type electrode assembly including a plurality of positive electrodes and negative electrodes.

[0036] Figure 2 is a side view showing a stacked / folded type electrode assembly according to the present invention.

[0037] Figure 3 is a side view showing a laminated / folding type electrode assembly according to the present invention.

[0038] Figure 4 is a graph showing the results according to Experimental Example 1.

[0039] Figure 5 is a graph showing the results according to Experimental Example 2.

[0040] Figure 6 is a graph showing the results according to Experimental Example 3. DETAILED DESCRIPTION

[0041] Now, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the preferred embodiments of the present invention. However, when describing in detail the operating principle of the preferred embodiments of the present invention, when the detailed description of the known functions and configurations incorporated herein will make the subject matter of the present invention unclear, the detailed description will be omitted.

[0042] In addition, the same reference numerals will be used throughout the drawings to represent components that perform similar functions or operations. Where a component is referred to as being connected to another component in the specification, not only may this component be directly connected to another component, but this component may also be indirectly connected to another component via other components. In addition, unless otherwise specified, the inclusion of a particular element does not mean that other elements are not included, but rather means that these elements may also be included.

[0043] The present invention relates to an all-solid-state battery, which comprises an electrode assembly and a solid electrolyte, wherein the electrode assembly has a structure of stacked plate electrodes.

[0044] Generally, an electrode assembly may be classified into a structure in which plate-shaped electrodes are stacked or a jelly-roll type electrode assembly structure in which long sheet-type electrodes are wound, such as a stacked type electrode assembly, a stacked / folded type electrode assembly, and a laminated / stacked type electrode assembly.

[0045] Since the jelly roll type electrode assembly includes one positive electrode and one negative electrode, the jelly roll type electrode assembly has a structure that makes it difficult to increase the variety of electrode configurations. On the other hand, since the stacking type, stacking / folding type, and lamination / stacked type electrode assemblies are configured so that a plurality of plate-shaped electrodes are stacked, various types of positive and negative electrodes can be applied.

[0046] Therefore, the electrode assembly of the all-solid-state battery according to the present invention includes a first electrode that generates relatively high heat and a second electrode that generates relatively low heat, wherein the first electrode may be disposed at the center of the electrode assembly.

[0047] The first electrode generating relatively high heat used in this specification is an electrode generating a relatively large amount of heat, and may be an electrode using an electrode active material generating high heat or an electrode having a solid electrolyte content ratio higher than that of the second electrode. The second electrode generating relatively low heat used in this specification is an electrode generating relatively low heat compared to the first electrode, and may be an electrode using an electrode active material generating low heat or an electrode having a solid electrolyte content ratio lower than that of the first electrode.

[0048] The first electrode may be located at the center of the electrode assembly, and thus, the first electrode may be disposed at the center of an electrode assembly consisting of a plurality of electrodes. Alternatively, a unit cell including or consisting of the first electrode may be disposed at the center of the electrode assembly. By placing the first electrode having a high exothermic property at the center of the electrode assembly, the temperature of the first electrode may be transferred to the second electrode, thereby increasing the internal temperature of the battery.

[0049] Generally, the first electrode generating high heat may damage the internal structure of the electrode or the electrode active material due to the high rate, thereby deteriorating the life characteristics. However, the second electrode generating low heat at a relatively stable rate may exhibit relatively excellent life characteristics due to less damage to the internal structure of the electrode or the electrode active material.

[0050] Therefore, in order to increase the overall temperature of the electrode assembly, when the electrode assembly includes both the first electrode generating high heat and the second electrode having stable life characteristics, the first electrode and the second electrode may complement each other's poor characteristics.

[0051] In this regard, Figure 1 is a side view showing a stacked type electrode assembly including a plurality of positive electrodes and negative electrodes.

[0052] refer to Figure 1 , Figure 1 The electrode assembly 100 of (a) is a stacked type electrode assembly having a structure in which a plurality of positive electrodes 101 and 101 ′ and a plurality of negative electrodes 102 are stacked with a solid electrolyte layer 103 interposed between the positive electrodes and the negative electrodes.

[0053] The positive electrode 101' disposed at the center of the electrode assembly 100 is a first electrode that generates high heat, and the positive electrode 101 disposed at the outside of the electrode assembly 100 is a second electrode that generates low heat. In addition, considering the performance of the battery, the two negative electrodes 102 can be simultaneously or selectively applied as the first negative electrode that generates high heat or the second negative electrode that generates low heat. As described above, by disposing the positive electrode that generates high heat at the center of the electrode assembly, heat energy can be transferred in the opposite direction based on the electrode stacking direction, thereby uniformly increasing the internal temperature of the battery.

[0054] Figure 1 The electrode assembly 110 of (b) is a stacked type electrode assembly having a structure in which a plurality of positive electrodes 111 and a plurality of negative electrodes 112 and 112 ′ are stacked with a solid electrolyte layer 113 interposed between the positive electrodes and the negative electrodes.

[0055] The negative electrode 112 ′ disposed at the center of the electrode assembly 110 may be a first negative electrode generating high heat, and the negative electrode 112 disposed at the outer side of the electrode assembly may be a second negative electrode generating low heat.

[0056] In addition, considering the performance of the battery, the two positive electrodes 111 can be simultaneously or selectively applied as the first positive electrode generating high heat or the second positive electrode generating low heat. As described above, by arranging the negative electrode generating high heat at the center of the electrode assembly, thermal energy can be transferred in the opposite direction based on the electrode stacking direction, thereby uniformly increasing the internal temperature of the battery.

[0057] In a specific example, each of the positive electrode 101 , the positive electrode 101 ′, the negative electrode 112 , and the negative electrode 112 ′ is different in the solid electrolyte content ratio, and the composition of the electrode active material may be the same.

[0058] For example, the negative electrode 112 and the negative electrode 112 ′ may be artificial graphite, natural graphite, natural graphite coated with artificial graphite, silicon oxide, hard carbon, or soft carbon.

[0059] In addition, the positive electrode 101 and the positive electrode 101 may be Ni-Co-Mn oxide (LiNCMO 2 (LiNCM)), lithium nickel oxide (LiNiO 2 (LNO)), olivine structure oxide (LFP (LiFePO 4 ) or LiMnPO 4 (LMP)), lithium cobalt oxide (LiCoO 2 (LCO) or lithium manganese oxide (LiMn 2 O 4 (LMO)).

[0060] In another specific example, the positive electrode 101 ′ and the negative electrode 112 ′ may have a form in which an electrode active material generating high heat is applied, and the positive electrode 101 and the negative electrode 112 may have a form in which an electrode active material generating low heat is applied.

[0061] When the heat generation of the negative electrode active materials is listed in order from high to low, it is hard carbon > soft carbon > artificial graphite > natural graphite coated with artificial graphite > natural graphite > silicon oxide. When the heat generation of the positive electrode active materials is listed in order from high to low, it is LMO > LCO > LiNCM > LNO > LMP, LFP.

[0062] The positive electrode 101' and the negative electrode 112' have relatively higher heat generation than the positive electrode 101 and the negative electrode 112. Therefore, considering the magnitude of the above heat generation, positive and negative electrodes generating relatively high heat and positive and negative electrodes generating relatively low heat may be selectively applied.

[0063] Alternatively, the positive electrode active material and the negative electrode active material may be selected from electrode active materials classified into a high heat generating group and a low heat generating group and used.

[0064] For example, the negative electrode 112 may be one or more selected from the group consisting of artificial graphite, natural graphite, natural graphite coated with artificial graphite, and silicon oxide, and the negative electrode 112 ′ may be one or more selected from the group consisting of hard carbon and soft carbon.

[0065] The positive electrode 101 may be a Ni-Co-Mn oxide (LiNCMO) containing more than 60% Ni. 2 , Ni>60%), lithium nickel oxide (LiNiO 2 (LNO)) and olivine structured oxide (LFP(LiFePO 4 ) or LiMnPO 4 The positive electrode 101' may be one or more selected from the group consisting of Ni-Co-Mn oxide (LiNCMO) containing 60% or less Ni. 2 , Ni<60%), lithium cobalt oxide (LiCoO 2 (LCO) and lithium manganese oxide (LiMn 2 O 4 (LMO)).

[0066] Figure 2 is a side view showing a stacked / folded type electrode assembly according to the present invention.

[0067] refer to Figure 2 The electrode assembly 200 is a stacked / folded type electrode assembly in which the solid electrolyte layer 290 is compressed and dual-cell type unit cells 210, 220, 230, 240, 250, 260, 270 and 280 are arranged on one side of the solid electrolyte layer 290, and the unit cells are configured to have a structure of positive electrode / solid electrolyte layer / negative electrode / solid electrolyte layer / positive electrode or negative electrode / solid electrolyte layer / positive electrode / solid electrolyte layer / negative electrode. The electrode assembly 200 prevents the solid electrolyte layer 290 from loosening by attaching a fixing tape 291 to the end of the solid electrolyte layer 290.

[0068] The electrode assembly 200 is composed of eight unit cells. Unit cells 210, 220, 230, and 240 disposed at the center of the electrode assembly are first unit cells including a first electrode having a high exothermic property, including an electrode active material having a high solid electrolyte content ratio or generating a large amount of heat when compared with unit cells 250, 260, 270, and 280 disposed at the outside of the electrode assembly. Unit cells 250, 260, 270, and 280 are second unit cells including a second electrode generating low heat.

[0069] In particular, both the positive electrode and the negative electrode constituting the first unit cell may be a first positive electrode generating high heat and a first negative electrode generating high heat. Alternatively, the first positive electrode generating high heat or the first negative electrode generating high heat may be applied only to one of the positive electrode or the negative electrode in the first unit cell.

[0070] However, both the positive electrode and the negative electrode constituting the second unit cell may be a second positive electrode that generates low heat and a second negative electrode that generates low heat.

[0071] Respectively, in the case of (i) applying different solid electrolyte content ratios and applying the same kind of electrode active material or (ii) applying an electrode active material that generates relatively high heat and an electrode active material that generates relatively low heat, the Figure 1 The same description as in the description of is applied to the first positive electrode and the first negative electrode and the second positive electrode and the second negative electrode, respectively.

[0072] and Figure 2 , only two of the first unit cells may be applied to the center, and the second unit cells may be applied to the six unit cells other than the first unit cells. Alternatively, the second unit cells may be applied to the unit cells 270 and 280 located at the outermost portion of the electrode assembly, and the first unit cells may be applied to the remaining six unit cells.

[0073] exist Figure 2 In the electrode assembly 200 of the embodiment, the positive electrode and the negative electrode constituting the first unit cells 210, 220, 230 and 240 may be designed to have the same electrode constituent materials such as electrode active materials, conductive agents and solid electrolytes. Alternatively, the positive electrode and the negative electrode constituting the first unit cells 210, 220, 230 and 240 may be designed to selectively differ in the type and / or component ratio of the electrode constituent materials in a state where the heat generated is higher than the heat generated by the second unit cells.

[0074] In addition, the positive electrodes and negative electrodes constituting the second unit cells 250, 260, 270, and 280 may be designed to have the same electrode constituent materials such as active materials, conductive agents, and solid electrolytes. Alternatively, the positive electrodes and negative electrodes constituting the second unit cells 250, 260, 270, and 280 may be designed to selectively differ in the type and / or composition ratio of the electrode constituent materials in a state where the heat generated is lower than the heat generated by the first unit cells.

[0075] Figure 3 is a side view showing a laminated / folding type electrode assembly according to the present invention.

[0076] Reference Figure 3, the electrode assembly 300 is a laminated / stacked electrode assembly, in which dual-cell type unit cells 310, 320, 330, 340, 350, 360, 370 and 380 having a structure of positive electrode / solid electrolyte layer / negative electrode / solid electrolyte layer / positive electrode or negative electrode / solid electrolyte layer / positive electrode / solid electrolyte layer / negative electrode are stacked and a solid electrolyte layer 390 is inserted therebetween and heat-sealed.

[0077] The unit cells 330, 340, 350 and 360 located at the center of the electrode assembly 300 are provided with Figure 2 The unit cells 310, 320, 370 and 380 located on the outer periphery of the electrode assembly 300 are high heat release unit cells having properties corresponding to the unit cells 210, 220, 230 and 240 of the first unit cell. Figure 2 The unit cells 250 , 260 , 270 , and 280 of the second unit cells correspond to low heat release unit cells of a property.

[0078] Therefore, the description of the unit cells 330 , 340 , 350 , and 360 and the unit cells 310 , 320 , 370 , and 380 of the electrode assembly 300 may be applied in the same manner as the description of the unit cells 210 , 220 , 230 , and 240 and the unit cells 250 , 260 , 270 , and 280 of the electrode assembly 200 .

[0079] The solid electrolyte can be a sulfide solid electrolyte, an oxide solid electrolyte or a polymer solid electrolyte.

[0080] It is preferred that the sulfide-based solid electrolyte contains sulfur atoms (S) to exhibit ionic conductivity of a metal belonging to Group I or Group II of the periodic table and exhibit electrical insulating properties. Although it is preferred that the sulfide-based solid electrolyte contains at least Li, S, and P as elements and has lithium ion conductivity, the sulfide-based solid electrolyte may contain elements other than Li, S, and P according to the purpose or as appropriate.

[0081] Specifically, examples of sulfide-based solid electrolytes are as follows. For example, Li 2 SP 2 S 5 , Li 2 SP 2 S 5 -LiCl, Li 2 SP 2 S 5 -H 2 S. Li 2 SP 2 S 5 -H 2S-LiCl、Li 2 S-LiI-P 2 S 5 、Li 2 S-LiI-Li 2 O-P 2 S 5 、Li 2 S-LiBr-P 2 S 5 、Li 2 SLi 2 O-P 2 S 5 、Li 2 S-Li 3 PO 4 -P 2 S 5 、Li 2 S-P 2 S 5 -P 2 O 5 、Li 2 S-P 2 S 5 -SiS 2 、Li 2 S-P 2 S 5 -SiS 2 -LiCl、Li 2 S-P 2 S 5 -SnS、Li 2 S-P 2 S 5 -Al 2 S 3 、Li 2 S-GeS 2 、Li 2 S-GeS 2 -ZnS、Li 2 S-Ga 2 S 3 、Li 2 S-GeS 2 -Ga 2 S 3 、Li 2 S-GeS 2 -P 2 S 5 、Li 2 S-GeS 2 -Sb 2 S 5 、Li 2 S-GeS 2 -Al2 S 3 , Li 2 SSiS 2 , Li 2 S-Al 2 S 3 , Li 2 S-SiS 2 -Al 2 S 3 , Li 2 S-SiS 2 -P 2 S 5 , Li 2 S-SiS 2 -P 2 S 5 -LiI, Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -Li 4 SiO 4 , Li 2 SSiS 2 -Li 3 PO 4 or Li 10 G 2 S 12 .

[0082] An example of a method for synthesizing a sulfide solid electrolyte material is an amorphization method. Examples of amorphization methods include mechanical grinding, solution method, and melt rapid cooling method. Among these methods, mechanical grinding is preferred because it can be processed at room temperature (25°C) and has the advantage of simplifying the manufacturing process.

[0083] It is preferable that the oxide-based solid electrolyte contains oxygen atoms (S) to exhibit ionic conductivity of a metal belonging to Group I or Group II of the periodic table and to exhibit electrical insulation.

[0084] As the oxide-based solid electrolyte, for example, Li xa La ya TiO 3 (xa=0.3 to 0.7 and ya=0.3 to 0.7) (LLT), Li xb La yb Zr zb M bb mb O nb (M bbis at least one of Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, or Sn, xb satisfies 5 ≤ xb ≤ 10, yb satisfies 1 ≤ yb ≤ 4, zb satisfies 1 ≤ zb ≤ 4, mb satisfies 0 ≤ mb ≤ 2, and nb satisfies 5 ≤ nb ≤ 20), Li xc B yc M cc zc O nc (M cc is at least one of C, S, Al, Si, Ga, Ge, In, or Sn, xc satisfies 0 ≤ xc ≤ 5, yc satisfies 0 ≤ yc ≤ 1, zc satisfies 0 ≤ zc ≤ 1, and nc satisfies 0 ≤ nc ≤ 6), Li xd (Al, Ga) yd (Ti, Ge) zd Si ad P md O nd (Here, 1 ≤ xd ≤ 3, 0 ≤ yd ≤ 1, 0 ≤ zd ≤ 2, 0 ≤ ad ≤ 1, 1 ≤ md ≤ 7, and 3 ≤ nd ≤ 13), Li (3-2xe) M ee xe D ee O (xe satisfies 0 ≤ xe ≤ 0.1, M ee is a divalent metal atom, D ee denotes a halogen atom or a combination of two or more halogen atoms), Li xf Si yf O zf (1 ≤ xf ≤ 5, 0 < yf ≤ 3, and 1 ≤ zf ≤ 10), Li xg S yg O zg (1 ≤ xg ≤ 3, 0 < yg ≤ 2, and 1 ≤ zg ≤ 10), Li with a lithium superionic conductor (LISICON)-type crystal structure 3.5 Zn 0.25 GeO 4 , Li 3 BO 3 -Li 2 SO 4 , Li 2 O-B 2 O 3 -P 2 O 5 , Li 2 O-SiO 2 , Li 6 BaLa 2 Ta 2 O 12 , Li 3 PO (4-3 / 2w) Nw (w<1), La with perovskite crystal structure 0.55 Li 0.35 TiO 3 , LiTi with NaASICON crystal structure 2 P 3 O 12 , Li 1+xh+yh (Al,Ga) xh (Ti,Ge) 2- xh Si yh P 3-yh O 12 (here, 0≤xh≤1 and 0≤yh≤1) or Li with a garnet-type crystal structure 7 La 3 Zr 2 O 12 (LLZ). In addition, a phosphorus compound including Li, P and O is preferably used. For example, lithium phosphate (Li 3 PO 4 ), LiPON or LiPOD in which part of the oxygen in lithium phosphate is replaced by nitrogen 1 (D 1 is at least one selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt and Au. In addition, LiA 1 ON(A 1 is at least one selected from Si, B, Ge, Al, C and Ga).

[0085] The polymer-based solid electrolyte may be a solid polymer electrolyte formed by adding a polymer resin to an independently solvated lithium salt, or a polymer gel electrolyte formed by impregnating a polymer resin with an organic electrolyte solution containing an organic solvent and a lithium salt.

[0086] The solid polymer electrolyte is not particularly limited as long as the solid polymer electrolyte is made of a polymer material such as an ion conductive and generally used as a solid electrolyte material for an all-solid-state battery. As examples of solid polymer electrolytes, polyether polymers, polycarbonate polymers, acrylate polymers, polysiloxane polymers, phosphazene polymers, polyethylene derivatives, alkylene oxide derivatives, phosphate polymers, poly-stirred lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, and polymers containing ionic dissociation groups can be mentioned. In a specific embodiment of the present invention, the solid polymer electrolyte may include: a branched copolymer formed by copolymerizing an amorphous polymer such as polymethyl methacrylate (PMMA), polycarbonate, polysiloxane, and / or phosphazene as a comonomer in the main chain of polyethylene oxide (PEO) as a polymer resin; a comb-like polymer resin; and a cross-linked polymer resin.

[0087] The polymer gel electrolyte includes an organic electrolyte solution containing a lithium salt and a polymer resin, wherein the amount of the organic electrolyte solution included is 60 parts by weight to 400 parts by weight based on the weight of the polymer resin. Although the polymer resin applied to the polymer gel electrolyte is not limited to a specific component, it may include PVC-based resins, polymethyl methacrylate (PMMA)-based resins, polyacrylonitrile (PAN), polyvinylidene fluoride (PVdF) and polyvinylidene fluoride hexafluoropropylene (PVdF-HFP).

[0088] Lithium salts are ionizable lithium salts that can be used with Li + X - Although the anion of the lithium salt is not particularly limited, F - , Cl - Br - ,I - 、NO 3 - ,N(CN) 2 - , BF 4 - , ClO 4 - PF 6 - ,(CF 3 ) 2 PF 4 - ,(CF 3 ) 3 PF 3 - ,(CF 3 ) 4 PF 2 - ,(CF3 ) 5 PF - ,(CF 3 ) 6 P - CF 3 SO 3 - CF 3 CF 2 SO 3 - ,(CF 3 SO 2 ) 2 N - 、(FSO 2 ) 2 N - CF 3 CF 2 (CF 3 ) 2 CO - ,(CF 3 SO 2 ) 2 CH - , (SF 5 ) 3 C - ,(CF 3 SO 2 ) 3 C - CF 3 (CF 2 ) 7 SO 3 - CF 3 CO 2 - , CH 3 CO 2 - 、SCN - or (CF 3 CF 2 SO 2 ) 2 N - .

[0089] Hereinafter, the present invention will be described with reference to the following examples. These examples are provided to make it easier to understand the present invention, and these examples should not be construed as limiting the scope of the present invention.

[0090] <Example 1>

[0091] like Figure 3 As shown in , a laminated / stacked type electrode assembly including eight unit cells is manufactured.

[0092] Among the unit cells, one unit cell generating high heat is arranged at the center of the electrode assembly, and seven unit cells generating low heat are arranged on both sides of the unit cell generating high heat, thereby completing the electrode assembly including a total of eight unit cells.

[0093] The unit cell that generates high heat includes 75% by weight of LiNi 0.8 Co 0.1 Mn 0.1 O 2 As the positive electrode active material, 5 wt% Super C as a conductive agent, 15 wt% polyethylene oxide (PEO) as a solid electrolyte, and 5 wt% polyvinylidene fluoride (PVDF) as a binder to prepare the positive electrode; and using 71 wt% artificial graphite as the negative electrode active material, 2 wt% Super C as a conductive agent, 23 wt% polyethylene oxide (PEO) as a solid electrolyte and 4 wt% styrene-butylene rubber (SBR) + carboxymethyl cellulose (CMC) as a binder to prepare the negative electrode.

[0094] The low heat generating unit cell includes 85 wt% LiNi 0.8 Co 0.1 Mn 0.1 O 2 As the positive electrode active material, 3 wt % of Super C as a conductive agent, 8 wt % of polyethylene oxide (PEO) as a solid electrolyte, and 4 wt % of polyvinylidene fluoride (PVDF) as a binder to prepare the positive electrode; and using 83 wt % of artificial graphite as the negative electrode active material, 1 wt % of Super C as a conductive agent, 13 wt % of polyethylene oxide (PEO) as a solid electrolyte and 3 wt % of styrene-butylene rubber (SBR) + carboxymethyl cellulose (CMC) as a binder to prepare the negative electrode.

[0095] A solid electrolyte layer interposed between the positive and negative electrodes was prepared and used by dissolving polyethylene oxide and LiFSI in acetonitrile at a ratio of 20 mol% and 1 mol% and casting them thinly on a glass plate, followed by vacuum drying to a thickness of 100 μm.

[0096] <Example 2>

[0097] An electrode assembly was manufactured using the same method as Example 1, except that the number of unit cells generating high heat was two and the number of unit cells generating low heat was six.

[0098] <Example 3>

[0099] An electrode assembly was manufactured using the same method as Example 1, except that the number of unit cells generating high heat was three and the number of unit cells generating low heat was five.

[0100] <Example 4>

[0101] An electrode assembly was manufactured using the same method as Example 1, except that the number of unit cells generating high heat was four and the number of unit cells generating low heat was four.

[0102] <Comparative Example 1>

[0103] like Figure 3 As shown in , a laminated / stacked type electrode assembly including eight unit cells is manufactured.

[0104] The unit cells all include electrodes having the same heat generating properties.

[0105] In particular, the unit cell includes 80 wt% LiNi 0.8 Co 0.1 Mn 0.1 O 2 As the positive electrode active material, 4 wt% Super C as a conductive agent, 10 wt% polyethylene oxide (PEO) as a solid electrolyte, and 6 wt% polyvinylidene fluoride (PVDF) as a binder to prepare the positive electrode; and using 77 wt% artificial graphite as the negative electrode active material, 1.5 wt% Super C as a conductive agent, 18 wt% polyethylene oxide (PEO) as a solid electrolyte and 3.5 wt% styrene-butylene rubber (SBR) + carboxymethyl cellulose (CMC) as a binder to prepare the negative electrode.

[0106] The electrode assembly of Comparative Example 1 was designed to have the same capacity as the electrode assemblies of Examples 1 to 4 at room temperature.

[0107] <Experimental Example 1>

[0108] In order to confirm the improvement level of the low temperature capacity of the electrode assembly including the electrode generating high heat, the secondary batteries including the electrode assemblies manufactured in Examples 1 to 4 and Comparative Example 1 were fully charged and fully discharged at -10°. Figure 4 A graph indicating the ratio of the improved capacity based on the capacity of Comparative Example 1 is shown.

[0109] Reference Figure 4 ,It can be seen that the capacity of the battery increases as the number of unit cells that generate high heat increases.

[0110] Since the experiment was performed under low temperature conditions, it was confirmed that the capacity improvement effect at low temperatures is excellent in the case of the present invention.

[0111] <Example 5>

[0112] like Figure 3 As shown in , a laminated / stacked type electrode assembly including eight unit cells is manufactured.

[0113] Among the unit cells, four unit cells generating high heat are arranged at the center of the electrode assembly, and two unit cells generating low heat are provided on each side of the unit cells generating high heat, thereby completing the electrode assembly including a total of eight unit cells.

[0114] The unit cell that generates high heat includes a negative electrode prepared using 80 wt% natural graphite as a negative electrode active material, 2 wt% Super C as a conductive agent, 13 wt% polyethylene oxide (PEO) as a solid electrolyte, and 5 wt% styrene-butylene rubber (SBR) + carboxymethyl cellulose (CMC) as a binder; and a negative electrode prepared using 80 wt% LiNi 0.8 Co 0.1 Mn 0.1 O 2 The positive electrode was prepared using 4 wt % of Super C as a conductive agent, 10 wt % of polyethylene oxide (PEO) as a solid electrolyte, and 6 wt % of polyvinylidene fluoride (PVDF) as a binder as the positive electrode active material.

[0115] The unit cell generating low heat is manufactured using the same method as the unit cell generating high heat, except that artificial graphite is used instead of natural graphite as a negative electrode active material for the unit cell generating high heat.

[0116] A solid electrolyte layer interposed between the positive and negative electrodes was prepared and used by dissolving polyethylene oxide and LiFSI in acetonitrile at a ratio of 20 mol% and 1 mol% and casting them thinly on a glass plate, followed by vacuum drying to a thickness of 100 μm.

[0117] <Example 6>

[0118] An electrode assembly was manufactured using the same method as in Example 5, except that soft carbon was used instead of the natural graphite used in the negative electrode for generating high heat in Example 5.

[0119] <Example 7>

[0120] An electrode assembly was manufactured using the same method as in Example 5, except that hard carbon was used instead of natural graphite for the negative electrode that generates high heat in Example 5.

[0121] <Comparative Example 2>

[0122] like Figure 3 As shown in , a laminated / stacked type electrode assembly including eight unit cells is manufactured.

[0123] The unit cells all include electrodes having the same heat generating properties.

[0124] Specifically, an electrode assembly was manufactured using the same positive electrode and solid electrolyte as in Example 5, except that a negative electrode including artificial graphite as a negative electrode active material was applied to the unit cell.

[0125] The electrode assembly of Comparative Example 2 was designed to have the same capacity as the electrode assemblies of Examples 5 to 7 at room temperature.

[0126] <Experimental Example 2>

[0127] In order to confirm the level of improvement in low-temperature capacity by applying negative electrode active materials having different heat generating properties, secondary batteries including the electrode assemblies manufactured in Examples 5 to 7 and Comparative Example 2 were fully charged and fully discharged at -10°. Figure 5 A graph indicating the ratio of the improved capacity based on the capacity of Comparative Example 2 is shown.

[0128] Reference Figure 5 , it can be seen that there is an effect of increasing the battery capacity according to the type of negative electrode active material. In particular, it was confirmed that the capacity of the battery increased in the order of natural graphite, soft carbon, and hard carbon.

[0129] Since the experiment was performed under low temperature conditions, it was confirmed that the capacity improvement effect at low temperatures is excellent in the case of the present invention.

[0130] <Comparative Example 3>

[0131] The electrode assembly was manufactured using the same method as in Example 1, except that two unit cells that generated high heat as in Example 1 were disposed at both ends of the electrode assembly and six unit cells that generated low heat as in Example 1 were disposed at the center of the electrode assembly so as to have Figure 3 The laminated / stacked electrode assembly shown in FIG. 1 includes eight unit cells.

[0132] <Experimental Example 3>

[0133] In order to confirm the improvement level of the battery capacity according to the position of the electrode generating high heat, the secondary batteries including the electrode assemblies manufactured in Example 2 and Comparative Example 3 were fully charged and fully discharged at -10°. Figure 6 A graph indicating the ratio of the improved capacity based on the capacity of Comparative Example 1 is shown.

[0134] Reference Figure 6, it can be seen that the secondary battery including the electrode assembly of Example 2 has a capacity improvement effect of about 3.5% compared to the secondary battery including the electrode assembly composed only of the electrode of Comparative Example 1 which uniformly generates heat.

[0135] However, the secondary battery including the electrode assembly of Comparative Example 3 in which unit cells generating high heat are disposed only at both ends of the electrode assembly exhibits a lower battery capacity than the secondary battery including the electrode assembly of Comparative Example 1.

[0136] Therefore, it can be seen that when the number of electrodes generating high heat is the same, the capacitance increasing effect is significantly increased when the electrodes generating high heat are arranged at the center of the electrode assembly rather than at both ends of the electrode assembly.

[0137] Those skilled in the art to which the present invention pertains will appreciate that, based on the above description, various applications and modifications are possible without departing from the scope of the present invention.

[0138] (Explanation of Reference Numerals)

[0139] 100, 110, 200, 300: electrode assembly

[0140] 101, 101', 111: positive electrode

[0141] 102, 112, 112': negative electrode

[0142] 103, 113, 290, 390: Solid electrolyte layer

[0143] 210, 220, 230, 240, 250, 260, 270, 280, 310, 320, 330, 340, 350, 360, 370, 380: unit cells

[0144] 291: Fixed belt

[0145] [Industrial Applicability]

[0146] As apparent from the above description, the all-solid-state secondary battery including the composite electrode according to the present invention partially includes an electrode that generates a large amount of heat, and thus, an overall temperature increase effect can be obtained due to heat energy generated during normal use of the battery.

[0147] In addition, by applying an electrode assembly including both an electrode generating high heat and an electrode generating low heat, it is possible to maintain not only the temperature increasing effect by the electrode generating high heat but also the life improving effect by the electrode generating low heat.

[0148] In addition, since a separate heat generating member for generating heat is not added, an additional external power source is not required, so that it is possible to prevent the volume of the battery from increasing in order to provide the external power source.

[0149] CROSS-REFERENCE TO RELATED APPLICATIONS

[0150] This patent application claims the benefit of priority to Korean Patent Application No. 2019-0053694, filed on May 8, 2019, the disclosure of which is hereby incorporated by reference in its entirety.

Claims

1. An all-solid-state battery, comprising an electrode assembly and a solid electrolyte, wherein: The electrode assembly includes a structure in which a plurality of positive electrodes and a plurality of negative electrodes are stacked and a solid electrolyte layer is interposed between the positive electrodes and the negative electrodes, and The electrodes include a first electrode and a second electrode, the first electrode generating higher heat than the second electrode during charge and discharge, thereby increasing the temperature by the first electrode and improving the lifespan by the second electrode, Wherein, the first electrode is arranged at the center of the electrode assembly, Wherein, the electrode assembly is a stacked electrode assembly, and The active material of the first electrode and the active material of the second electrode are negative electrode active materials selected from hard carbon, soft carbon, artificial graphite, natural graphite coated with artificial graphite, natural graphite and silicon oxide, wherein the content ratio of the solid electrolyte in the first electrode based on the total solid content is higher than the content ratio of the solid electrolyte in the second electrode based on the total solid content.

2. The all-solid-state battery according to claim 1, wherein: The negative electrode active material of the first electrode generates higher heat than the negative electrode active material of the second electrode during charge and discharge.

3. The all-solid-state battery according to claim 1, wherein: The electrode assembly is a laminated / stacked type electrode assembly or a stacked / folded type electrode assembly including a plurality of unit cells; The plurality of unit cells are configured to have a first unit cell including the first electrode and a second unit cell including the second electrode; and During charging and discharging, the first electrode generates higher heat than the second electrode.

4. The all-solid-state battery according to claim 3, wherein: The first electrode of the first unit cell and the second electrode of the second unit cell have the same composition of negative electrode active material.

5. The all-solid-state battery according to claim 1, wherein: The solid electrolyte is a sulfide solid electrolyte, an oxide solid electrolyte or a polymer solid electrolyte.

6. The all-solid-state battery according to claim 1, wherein: The temperature of the first electrode is transferred to the second electrode to increase the internal temperature of the battery.

7. An all-solid-state battery, comprising an electrode assembly and a solid electrolyte, wherein: The electrode assembly includes a structure in which plate-shaped electrodes are stacked, and The electrodes include a first electrode and a second electrode, the first electrode generating higher heat than the second electrode during charge and discharge, thereby increasing the temperature by the first electrode and improving the lifespan by the second electrode, Wherein, the first electrode is arranged at the center of the electrode assembly, wherein the electrode assembly is a laminated / stacked electrode assembly or a stacked / folded electrode assembly including a plurality of unit cells, the plurality of unit cells being configured to have a first unit cell including the first electrode and a second unit cell including the second electrode, and The first electrode and the second electrode have the same active material composition, wherein a content ratio of the solid electrolyte in the first electrode based on the total solid content is higher than a content ratio of the solid electrolyte in the second electrode based on the total solid content.

8. A battery pack comprising the all-solid-state battery according to any one of claims 1 to 7.

9. A device comprising the battery pack according to claim 8, wherein: The device is any one selected from the group consisting of a mobile electronic device, a wearable electronic device, a tablet computer, a laptop computer, an electric vehicle, and a power storage device.

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