Positive electrode and battery using the same

Abstract

To provide a positive electrode which can enhance the safety of a battery, and a battery using the positive electrode.SOLUTION: There are provided a positive electrode and a battery using the positive electrode. The positive electrode includes a positive electrode active layer and a first layer, and the first layer is arranged on the positive electrode active layer. The first layer includes oxide containing lithium iron phosphorus and a first binder. The electric resistance ratio of the first layer and the positive electrode active layer is at least 100.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a positive electrode and a battery using the same. [Background technology]

[0002] Lithium-ion secondary batteries are the mainstream commercial product and they are currently being developed to be lighter, smaller in volume, and safer, as well as to have higher energy capacity and longer cycle life. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 9,196,901 B2 Summary of the Invention [Problem to be solved by the invention]

[0004] Internal short circuits are a phenomenon that seriously affects the safety of lithium batteries. When an internal short circuit occurs, the resistance at the shorted point approaches zero, causing the energy contained in the battery to flow in the form of a large current and the immediate release of a huge amount of heat energy. This can cause a series of safety issues, including leakage, swelling, heat generation, smoke, combustion, or explosion, significantly limiting the usability of the battery.

[0005] The causes of short circuits include changes in the internal stress state within the battery, such as the growth of needle-like lithium dendrites or pressure on the battery, which causes electrical conduction between the positive and negative electrodes within the battery. If the occurrence of a chain reaction during a short circuit within the battery can be reduced (i.e., the period of energy release can be extended), the safety of the battery can be improved.

[0006] Therefore, new battery electrode materials and assembly designs are required to solve the above problems. [Means for solving the problem]

[0007] The present disclosure provides a positive electrode, which includes a positive electrode active layer and a first layer disposed on the positive electrode active layer. The first layer may include a lithium-iron-phosphorus-containing oxide and a first binder, and the electrical resistance ratio between the first layer and the positive electrode active layer is 100 or greater.

[0008] According to some embodiments of the present disclosure, the present disclosure provides a positive electrode. The positive electrode includes a positive electrode active layer, a first layer, and a second layer. The first layer may be disposed on the positive electrode active layer, and the second layer may be disposed on the first layer. The first layer includes a lithium iron phosphorus-containing oxide and a first binder, and the second layer includes stabilized lithium metal particles.

[0009] According to an embodiment of the present disclosure, the present disclosure also provides a battery, which includes the positive electrode of the present disclosure, a separator, and a negative electrode, the negative electrode being separated from the positive electrode by the separator. [Effects of the Invention]

[0010] The present disclosure provides a positive electrode (e.g., a positive electrode for a lithium battery) and a battery (e.g., a lithium battery) using the same. According to an embodiment of the present disclosure, the positive electrode of the present disclosure includes a positive electrode active layer and a first layer (comprising a lithium iron phosphorus-containing oxide), where the first layer exhibits relatively high resistance and thermal stability. The first layer of the present disclosure is suitable for use with the positive electrode active layer and can function as a fail-safe layer. A specific resistance ratio between the first layer and the positive electrode active layer can extend the time during which an internal short circuit occurs in a lithium battery including the positive electrode when the battery is overcharged. Furthermore, when a lithium battery including the positive electrode experiences an internal short circuit, the battery energy release can be slowed down (i.e., the energy release rate is reduced), thereby improving the safety of the lithium battery during use. The present invention can be more fully understood from the following detailed description and examples, taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view of a positive electrode of a battery according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view of a positive electrode of a battery according to another embodiment of the present disclosure. [Figure 3] FIG. 2 is a cross-sectional view of a positive electrode of a battery according to another embodiment of the present disclosure. [Figure 4] FIG. 1 is a schematic diagram of a battery including a positive electrode according to an embodiment of the present disclosure. [Figure 5] FIG. 2 is a schematic diagram of a battery including a positive electrode according to another embodiment of the present disclosure. [Figure 6] FIG. 1 is a schematic diagram of a battery including a positive electrode according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] The positive electrode of the present disclosure and a battery using the same are described in detail below. In the following detailed description, for purposes of explanation, numerous specific details and embodiments are set forth to provide a thorough understanding of the present disclosure. The specific elements and configurations described in the following detailed description are set forth to clearly explain the present disclosure. However, it will be apparent that the exemplary embodiments shown herein are used for illustrative purposes only, and that the inventive concept can be embodied in various forms without being limited to these exemplary embodiments. In addition, to clearly explain the present disclosure, similar and / or corresponding numerals may be used in the drawings of different embodiments to indicate similar and / or corresponding elements. However, the use of similar and / or corresponding numerals in the drawings of different embodiments does not imply any correlation between the different embodiments. As used herein, the term "about" in quantitative terms refers to plus or minus an amount that is common and reasonable to one of ordinary skill in the art.

[0013] It should be noted that the elements or devices in the figures of this disclosure may be present in any form or configuration known to one of ordinary skill in the art. Additionally, the phrases "a layer overlying another layer," "a layer disposed on top of another layer," "a layer disposed on another layer," and "a layer disposed above another layer" may refer to a layer that is in direct contact with another layer, and may also refer to a layer that is not in direct contact with another layer, but has one or more intermediate layers between them.

[0014] Furthermore, the use of ordinal terms in this disclosure, such as "first," "second," "third," etc., to modify elements does not, in and of itself, imply any priority, precedence, or order of one claim element relative to another, or any chronological order in which they are formed, but is merely used as a marker to distinguish one claim element having a particular name from another element having the same name (in the absence of any ordinal term), thereby distinguishing between claim elements.

[0015] The depicted figures are only schematic and non-limiting. For illustrative purposes, the size, shape, or thickness of some of the elements in the figures may be exaggerated and not drawn to scale. The dimensions and relative dimensions do not correspond to an actual location for practicing the present disclosure. While the present disclosure will be described with respect to certain embodiments and with reference to certain figures, the disclosure is not limited thereto.

[0016] According to an embodiment of the present disclosure, a positive electrode of the present disclosure includes a positive electrode active layer and a composite layer, and the composite layer exhibits relatively high resistance and thermal stability. The composite layer is suitable for use with the positive electrode active layer and functions as a fail-safe layer. Because the composite layer includes a first layer (including a lithium iron phosphorus-containing oxide) and a second layer (including stabilized lithium metal particles (SLMP)), the safety of the lithium battery (including the positive electrode of the present disclosure) can be improved, and the discharging specific capacity of the lithium battery can be increased, provided that the capacity retention rate is not reduced.

[0017] According to an embodiment of the present disclosure, the present disclosure provides a positive electrode that can function as a battery positive electrode (e.g., a positive electrode of a lithium battery). According to an embodiment of the present disclosure, as shown in FIG. 1 , a positive electrode 10 of the present disclosure may include a positive electrode active layer 12 and a first layer 14 (e.g., a fail-safe layer), and the first layer 14 may be disposed on the positive electrode active layer 12. According to an embodiment of the present disclosure, the positive electrode active layer 12 includes a positive electrode active material, and the first layer 14 includes a lithium iron phosphorus-containing oxide (e.g., lithium iron manganese phosphate (LMFP), lithium iron phosphorus (LFP), or a combination thereof). In addition, the lithium iron phosphorus-containing oxide may be further doped with nickel, cobalt, neodymium, praseodymium, erbium, yttrium, vanadium, molybdenum, or a combination thereof. In order to achieve the purpose of extending the time for an internal short circuit to occur in the battery and slowing down the release of battery energy when the battery is short-circuited, the electrical resistance ratio between the first layer and the positive electrode active layer can be greater than 100. For example, the electrical resistance ratio between the first layer and the positive electrode active layer can be between 100 and 1×10 8 For example, the electrical resistance ratio between the first layer and the positive electrode active layer is 100 to 1×10 6 (e.g., 3×10 2 , 1×10 3 , 6×10 4 , or 7 × 10 5 ). If the electrical resistance ratio between the first layer and the positive electrode active layer is too low, the safety of the battery cannot be enhanced. If the electrical resistance ratio between the first layer and the positive electrode active layer is too high, the resistance of the first layer will be higher, resulting in a significant decrease in battery performance. The resistance of the first layer and the positive electrode active layer of the present disclosure is measured using a four-probe resistance meter (DU-5211 Ohm Meter, commercially available from DELTA UNITED INSTRUMENT CO. LTD). The method includes the following steps: A sample is placed in the four-probe resistance meter; the probes are brought into contact with the surface of the sample under a pressure of 0.07 MPa; after contact, the system is allowed to stand for 3 seconds before measuring the resistance (ohms) using the four-probe resistance meter.

[0018] According to embodiments of the present disclosure, the thickness of the positive electrode active layer 12 is not limited and can be arbitrarily changed by those having ordinary knowledge in the art. For example, the thickness of the positive electrode active layer 12 may be from about 50 μm to 200 μm (for example, about 70 μm, 100 μm, 150 μm or 180 μm). According to embodiments of the present disclosure, the thickness of the first layer 14 is not limited and can be arbitrarily changed by those having ordinary knowledge in the art. For example, the thickness of the first layer 14 may be from about 1 μm to 50 μm (for example, about 2 μm, 5 μm, 10 μm, 20 μm, 30 μm or 40 μm).

[0019] According to embodiments of the present disclosure, the positive electrode active material may be sulfur, an organic sulfide, a sulfur-carbon composite, a lithium-containing metal oxide, a lithium-containing metal sulfide, a lithium-containing metal selenide, a lithium-containing metal telluride, a lithium-containing metal silicide, a lithium-containing metal boride, or a combination thereof, and the metal is selected from the group consisting of aluminum, vanadium, titanium, chromium, copper, molybdenum, niobium, iron, nickel, cobalt and manganese. According to embodiments of the present disclosure, the positive electrode active material may be lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium cobalt manganese oxide, lithium nickel cobalt oxide, lithium nickel manganese oxide, lithium nickel manganese cobalt oxide, lithium chromium manganese oxide, lithium nickel vanadium oxide, lithium manganese nickel oxide, lithium cobalt vanadium oxide, lithium nickel cobalt aluminum oxide or a combination thereof. According to embodiments of the present disclosure, the lithium nickel manganese cobalt oxide may have a chemical structure LiNi x Co y Mn z O2, where 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1. According to embodiments of the present disclosure, the lithium nickel cobalt aluminum oxide may have a chemical structure LiNi 0.80 Co 0.15 Al 0.05According to embodiments of the present disclosure, the lithium cobalt oxide may have the chemical structure LiCoO.

[0020] According to an embodiment of the present disclosure, the positive electrode active layer 12 may further include a binder, which may include polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), carboxymethyl cellulose, sodium carboxymethyl cellulose, polyvinylidene fluoride (PVDF), styrene-butadiene copolymer, fluororubber, polyurethane, polyvinylpyrrolidone, poly(ethyl acrylate), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polybutadiene, polyacrylic acid (PAA), or a combination thereof. According to an embodiment of the present disclosure, in the positive electrode active layer 12, the weight percentage of the positive electrode active material may be about 90 wt % to 99.9 wt % (e.g., 91 wt %, 92 wt %, 93 wt %, 94 wt %, 95 wt %, 96 wt %, 97 wt %, 98 wt %, or 99 wt %), and the weight percentage of the binder may be about 0.1 wt % to 10 wt % (e.g., 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, or 9 wt %), based on the total weight of the positive electrode active material and binder. According to an embodiment of the present disclosure, the weight ratio of the binder to the positive electrode active material in the positive electrode active layer 12 may be 0.1:99.9 to 10:90 (e.g., 1:99, 2:98, 3:97, 4:96, 5:95, 6:94, 7:93, 8:92, or 9:91). According to an embodiment of the present disclosure, the positive electrode active layer 12 may consist of the binder and the positive electrode active material.

[0021] According to an embodiment of the present disclosure, the positive electrode active layer 12 may further include a conductive additive, which may be conductive carbon black, conductive graphite, fluorocarbon, reduced graphene, nitrogen-doped graphite, nitrogen-doped graphene, carbon fiber, carbon nanotube, or a combination thereof. According to an embodiment of the present disclosure, in the positive electrode active layer 12, based on the total weight of the positive electrode active material, binder, and conductive additive, the weight percentage of the positive electrode active material may be approximately 90 wt % to 99.8 wt % (e.g., 91 wt %, 92 wt %, 93 wt %, 94 wt %, 95 wt %, 96 wt %, 97 wt %, 98 wt %, or 99 wt %), the weight percentage of the binder may be approximately 0.1 wt % to 6 wt % (e.g., 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, or 5.5 wt %), and the weight percentage of the conductive additive may be approximately 0.1 wt % to 6 wt % (e.g., 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, or 5.5 wt %). According to an embodiment of the present disclosure, the weight ratio of the binder to the positive electrode active material in the positive electrode active layer 12 may be 1:99 to 5:95 (e.g., 1.5:98.5, 2:98, 3:97, 4:96, or 4.5:95.5), and the weight ratio of the conductive additive to the positive electrode active material may be 1:99 to 5:95 (e.g., 1.5:98.5, 2:98, 3:97, 4:96, or 4.5:95.5). According to an embodiment of the present disclosure, the positive electrode active layer 12 may be composed of the binder, the conductive additive, and the positive electrode active material.

[0022] According to an embodiment of the present disclosure, the lithium iron phosphorus-containing oxide may be lithium iron manganese phosphate. The chemical structure of lithium iron manganese phosphate is LiMn x Fe 1-xPO4, where 0≦x<1, for example, x may be 0.51, 0.52, 0.53, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 0.97, 0.98, or 0.99. According to an embodiment of the present disclosure, the particle size of the lithium iron phosphorus-containing oxide is not limited and can be arbitrarily changed by a person skilled in the art, and may be 1 nm to 100 μm, for example, 10 nm, 50 nm, 100 nm, 500 nm, 1 μm, 10 μm, 50 μm, or 80 μm.

[0023] According to embodiments of the present disclosure, the first layer 14 may further include a first binder, which may include polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), carboxymethyl cellulose, sodium carboxymethyl cellulose, polyvinylidene fluoride (PVDF), styrene-butadiene copolymer, fluororubber, polyurethane, polyvinylpyrrolidone, poly(ethyl acrylate), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polybutadiene, polyacrylic acid (PAA), or a combination thereof. According to an embodiment of the present disclosure, in the first layer 14, the weight percentage of the lithium iron phosphorus-containing oxide may be approximately 90 wt % to 99.9 wt % (e.g., 91 wt %, 92 wt %, 93 wt %, 94 wt %, 95 wt %, 96 wt %, 97 wt %, 98 wt %, or 99 wt %), and the weight percentage of the first binder may be approximately 0.1 wt % to 10 wt % (e.g., 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, or 9 wt %), based on the total weight of the lithium iron phosphorus-containing oxide and the first binder. According to an embodiment of the present disclosure, the weight ratio of the first binder to the lithium iron phosphorus-containing oxide in the first layer 14 may be 1:99 to 5:95 (e.g., 1.5:98.5, 2:98, 3:97, 4:96, or 4.5:95.5). According to an embodiment of the present disclosure, the first layer 14 may consist of the first binder and the lithium iron phosphorus-containing oxide.

[0024] According to embodiments of the present disclosure, the first layer 14 may further include an inorganic powder, which may be a conductive powder, a metal oxide, or a combination thereof. According to embodiments of the present disclosure, the conductive powder may be a metal, an alloy thereof, conductive carbon black, conductive graphite, fluorocarbon, reduced graphene, nitrogen-doped graphite, nitrogen-doped graphene, carbon fiber, carbon nanotubes, or a combination thereof, where the metal may be zirconium, chromium, molybdenum, tungsten, manganese, iron, osmium, cobalt, nickel, palladium, platinum, copper, silver, gold, zinc, indium, tin, lead, or aluminum. According to embodiments of the present disclosure, the metal oxide may be aluminum oxide, zirconium oxide, zinc oxide, silicon oxide, tin oxide, or a combination thereof. According to an embodiment of the present disclosure, the particle size of the inorganic powder is not limited and can be arbitrarily changed by a person skilled in the art, and may be 1 nm to 100 μm, for example, 10 nm, 50 nm, 100 nm, 500 nm, 1 μm, 10 μm, 50 μm, or 80 μm. According to an embodiment of the present disclosure, the weight percentage of the lithium iron phosphorus-containing oxide in the first layer 14 may be about 90 wt % to 99.8 wt % (e.g., 91 wt %, 92 wt %, 93 wt %, 94 wt %, 95 wt %, 96 wt %, 97 wt %, 98 wt %, or 99 wt %) with respect to the total weight of the lithium iron phosphorus-containing oxide, the first binder, and the inorganic powder. The amount percentage may be about 0.1 wt% to 6 wt% (e.g., 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or 6 wt%), and the weight percentage of the inorganic powder may be about 0.1 wt% to 4 wt% (e.g., 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 1 wt%, 2 wt%, or 3 wt%).According to an embodiment of the present disclosure, the weight ratio of the first binder to the lithium iron phosphorus-containing oxide in the first layer 14 may be 1:99 to 5:95 (e.g., 1.5:98.5, 2:98, 3:97, 4:96, or 4.5:95.5), and the weight ratio of the inorganic powder to the lithium iron phosphorus-containing oxide may be 0.1:99.9 to 1:99 (e.g., 0.2:99.8, 0.5:99.5, or 0.8:99.2). According to an embodiment of the present disclosure, the first layer 14 may consist of the first binder, the inorganic powder, and the lithium iron phosphorus-containing oxide.

[0025] According to an embodiment of the present disclosure, as shown in FIG. 2 , a positive electrode 10 of the present disclosure may include a positive electrode active layer 12, a first layer 14, and a positive electrode current collecting layer 16, where the positive electrode active layer 12 may be disposed on the positive electrode current collecting layer 16 and the first layer 14 may be disposed on the positive electrode active layer 12.

[0026] According to an embodiment of the present disclosure, a method for fabricating the positive electrode 10 shown in FIG. 2 may include the following steps: First, components of the positive electrode active layer (e.g., a positive electrode active material, a conductive additive, and a binder) are dispersed in a solvent (e.g., 1-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), pyrrolidone, N-dodecylpyrrolidone, γ-butyrolactone, or a combination thereof) to obtain a positive electrode active layer slurry. The solid content of the positive electrode active layer slurry may be approximately 30 wt % to 80 wt %. Next, a positive electrode current collecting layer 16 is prepared. A coating of the positive electrode slurry is then formed on the positive electrode current collecting layer 16 by a spreading process. The coating is then subjected to a drying process (at a temperature of 90° C. to 180° C.) to obtain a positive electrode active layer 12. Next, the components of the first layer (e.g., lithium iron phosphorus-containing oxide, inorganic powder, and first binder) are dispersed in a solvent to obtain a first slurry. A coating of the first slurry is then formed on the positive electrode active layer 12 by a coating process. The coating is then subjected to a drying process (at a temperature of about 90°C to 180°C) to obtain the first layer 14. The coating process may be screen printing, spin coating, bar coating, blade coating, roller coating, solvent casting, or dip coating.

[0027] The thickness of the positive electrode current collecting layer 16 is not limited and can be arbitrarily changed by a person skilled in the art. For example, the thickness of the positive electrode current collecting layer 16 may be about 5 μm to 200 μm (e.g., about 10 μm, 30 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or 150 μm).

[0028] According to an embodiment of the present disclosure, the positive electrode current collecting layer 16 may be a conductive carbon substrate, a metal foil, or a metal material having a porous structure, such as carbon cloth, carbon felt, carbon paper, copper foil, nickel foil, aluminum foil, nickel mesh, copper mesh, molybdenum mesh, nickel foam, copper foam, or molybdenum foam. According to an embodiment of the present disclosure, the porosity of the metal material having a porous structure may be about 10% to 99.9% (e.g., 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%).

[0029] According to an embodiment of the present disclosure, as shown in FIG. 3 , a positive electrode 10 of the present disclosure may include a positive electrode active layer 12, a first layer 14, a positive electrode current collecting layer 16, and a second layer 18, where the positive electrode active layer 12 may be disposed on the positive electrode current collecting layer 16, the first layer 14 may be disposed on the positive electrode active layer 12, and the second layer 18 may be disposed on the first layer 14.

[0030] According to the embodiment of the present disclosure, the thickness of the second layer 18 is not limited and can be arbitrarily changed by a person skilled in the art. For example, the thickness of the second layer 18 may be about 10 nm to 1 μm (e.g., about 20 nm, 30 nm, 50 nm, 80 nm, 100 nm, 200 nm, 300 nm, 500 nm, 600 nm, 800 nm, or 900 nm).

[0031] According to an embodiment of the present disclosure, the second layer 18 includes an inorganic powder, which may be a metal oxide, stabilized lithium metal particles, or a combination thereof. According to an embodiment of the present disclosure, the metal oxide may be aluminum oxide, zirconium oxide, zinc oxide, silicon oxide, tin oxide, or a combination thereof. According to an embodiment of the present disclosure, the stabilized lithium metal particles have a substantially core-shell structure, including a core and a shell encapsulating the core. The core may include lithium metal or a lithium metal alloy. The shell includes a lithium salt and surrounds and encapsulates the core. The shell may be hermetically sealed, thereby preventing or substantially inhibiting contact and reaction with water or air (including oxygen) with the core. According to an embodiment of the present disclosure, the core includes elemental lithium. According to an embodiment of the present disclosure, the core may include a lithium alloy, which includes lithium and at least one element selected from the group consisting of aluminum, silicon, germanium, tin, lead, and bismuth. The shell includes a lithium salt, which may include a lithium complex, such as LiPF, LiBF, LiClO, LiAsF, LiFSO, LiCO, or a combination thereof. The stabilized lithium metal particles are substantially non-reactive or non-flammable when exposed to air, oxygen, or water. The stabilized lithium metal particles may be chemically inert under the following conditions: for example, exposure to ambient air, air, oxygen, or high-temperature water vapor. The high temperature may be greater than 50°C, 100°C, 150°C, or 200°C. According to embodiments of the present disclosure, the particle size of the inorganic powder is not limited and can be freely varied by one skilled in the art. The particle size of the inorganic powder may be 1 nm to 1 μm, for example, 5 nm, 10 nm, 20 nm, 30 nm, 50 nm, 80 nm, 100 nm, 200 nm, 300 nm, 500 nm, 600 nm, 800 nm, or 900 nm.

[0032] According to embodiments of the present disclosure, the second layer 18 may further include a second binder, which may include polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), carboxymethyl cellulose, sodium carboxymethyl cellulose, polyvinylidene fluoride (PVDF), styrene-butadiene copolymer, fluororubber, polyurethane, polyvinylpyrrolidone, poly(ethyl acrylate), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polybutadiene, polyacrylic acid (PAA), or a combination thereof. According to an embodiment of the present disclosure, in the second layer 18, the weight percentage of the inorganic powder may be about 90 wt % to 99.9 wt % (e.g., 91 wt %, 92 wt %, 93 wt %, 94 wt %, 95 wt %, 96 wt %, 97 wt %, 98 wt %, or 99 wt %), and the weight percentage of the second binder may be about 0.1 wt % to 10 wt % (e.g., 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, or 9 wt %), based on the total weight of the inorganic powder and the second binder. According to embodiments of the present disclosure, the weight ratio of the second binder to the inorganic powder in the second layer 18 may be 0.1:99.9 to 10:90 (e.g., 1:99, 2:98, 3:97, 4:96, 5:95, 6:94, 7:93, 8:92, or 9:91). According to embodiments of the present disclosure, the second layer 18 may consist of the second binder and the inorganic powder.

[0033] According to an embodiment of the present disclosure, as shown in FIG. 3 , a positive electrode 10 of the present disclosure includes a positive electrode current collecting layer 16, a positive electrode active layer 12, a first layer 14, and a second layer 18, in this order, where the first layer 14 includes a lithium iron phosphorus-containing oxide (e.g., lithium iron manganese phosphate (LMFP)), and the second layer includes stabilized lithium metal particles (SLMP). According to an embodiment of the present disclosure, the stack including the first layer 14 and the second layer 18 can function as a fail-safe layer. According to an embodiment of the present disclosure, the first layer 14 can include a first binder and a lithium iron phosphorus-containing oxide. According to an embodiment of the present disclosure, the first layer 14 can include a first binder, an inorganic powder, and a lithium iron phosphorus-containing oxide. According to an embodiment of the present disclosure, the first layer 14 can consist of a first binder and a lithium iron phosphorus-containing oxide. According to an embodiment of the present disclosure, the first layer 14 may comprise a first binder, an inorganic powder, and a lithium iron phosphorus-containing oxide. According to an embodiment of the present disclosure, the second layer 18 may comprise a second binder and stabilized lithium metal particles. According to an embodiment of the present disclosure, the second layer 18 may comprise a second binder and stabilized lithium metal particles. According to embodiments of the present disclosure, in second layer 18, the weight percentage of the stabilized lithium metal particles may be about 90 wt % to 99.9 wt % (e.g., 91 wt %, 92 wt %, 93 wt %, 94 wt %, 95 wt %, 96 wt %, 97 wt %, 98 wt %, or 99 wt %), and the weight percentage of the second binder may be about 0.1 wt % to 10 wt % (e.g., 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, or 9 wt %), based on the total weight of the stabilized lithium metal particles and second binder. According to embodiments of the present disclosure, in second layer 18, the weight ratio of second binder to stabilized lithium metal particles may be from 0.1:99.9 to 10:90 (e.g., 1:99, 2:98, 3:97, 4:96, 5:95, 6:94, 7:93, 8:92, or 9:91).

[0034] According to an embodiment of the present disclosure, a method for fabricating the positive electrode 10 shown in FIG. 3 may include the following steps: First, components of the positive electrode active layer (e.g., a positive electrode active material, a conductive additive, and a binder) are dispersed in a solvent (e.g., 1-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), pyrrolidone, N-dodecylpyrrolidone, γ-butyrolactone, or a combination thereof) to obtain a positive electrode active layer slurry. The solid content of the positive electrode active layer slurry may be 30 wt % to 80 wt %. Next, a positive electrode current collecting layer 16 is prepared. A coating of the positive electrode active layer slurry is then formed on the positive electrode current collecting layer 16 by a spreading process. The coating is then subjected to a drying process (at a temperature of about 90° C. to 180° C.) to obtain a positive electrode active layer 12. Next, the components of the first layer (e.g., lithium iron phosphorus oxide and a first binder) are dispersed in a solvent to obtain a first slurry. The first slurry is then formed on the positive electrode active layer 12 by a coating process. The coating is then subjected to a drying process (at a temperature of about 90°C to 180°C) to obtain the first layer 14. The components of the second layer (e.g., stabilized lithium metal particles) are then placed on the first layer 14 to form a powder layer. Pressure is then applied to the powder layer to obtain the second layer 18. The pressure application method may be a calendaring process or a rolling process. In some embodiments, the method of forming the second layer 18 may include the following steps after the formation of the first layer 14: The components of the second layer (e.g., stabilized lithium metal particles and a second binder) are dispersed in a solvent to obtain a second slurry. The second slurry is then formed on the first layer 14 by a coating process. The coating is subjected to a drying process (at a temperature of about 90° C. to 180° C.) to obtain the second layer 18. The application process can be screen printing, spin coating, bar coating, blade coating, roller coating, solvent casting or dip coating.

[0035] According to an embodiment of the present disclosure, the present disclosure also provides a battery 100, such as a lithium battery, a lithium-ion battery, or a lithium metal battery, as shown in FIG. 4. The battery 100 includes a positive electrode 10, a separator 20, and a negative electrode 30, as shown in FIG. 2. The negative electrode 30 is separated from the positive electrode 10 via the separator 20. According to an embodiment of the present disclosure, the positive electrode 10 may be in direct contact with the separator 20, and / or the negative electrode 30 may be in direct contact with the separator 20. According to an embodiment of the present disclosure, the positive electrode 10 may be spaced a specific distance from the separator 20, and / or the negative electrode 30 may be spaced a specific distance from the separator 20. According to an embodiment of the present disclosure, the battery 100 may further include a liquid electrolyte 40, which is disposed between the positive electrode 10 and the negative electrode 30. That is, the stacked structure of the positive electrode 10, separator 20, and negative electrode 30 is immersed in the liquid electrolyte 40 (i.e., the battery 100 is filled with the liquid electrolyte). According to some embodiments of the present disclosure, the positive electrode active layer 12 of the present disclosure may be disposed between the separator 20 and the positive electrode current collecting layer 16, the first layer 14 of the present disclosure may be disposed between the separator 20 and the positive electrode active layer 12, and the first layer 14 of the present disclosure may be in direct contact with the separator 20. According to embodiments of the present disclosure, the battery 100 of the present disclosure may be composed of the positive electrode 10, separator 20, negative electrode 30, and liquid electrolyte 40. According to embodiments of the present disclosure, as shown in FIG. 5, the battery 100 may include the positive electrode 10, separator 20, negative electrode 30, and liquid electrolyte 40 shown in FIG. 3.

[0036] According to embodiments of the present disclosure, separator 20 may include an insulating material, such as polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), polyamide, polyvinyl chloride (PVC), poly(vinylidene fluoride), polyaniline, polyimide, polyethylene terephthalate, polystyrene (PS), cellulose, or a combination thereof. For example, separator 20 may have a PE / PP / PE multilayer composite structure. According to embodiments of the present disclosure, the separator may have a porous structure. That is, the pores of the separator are uniformly distributed throughout the separator.

[0037] According to embodiments of the present disclosure, the liquid electrolyte 40 may include a solvent and a lithium salt (or a lithium-containing compound). According to embodiments of the present disclosure, the concentration of the lithium salt in the solvent may be about 0.8 M to 1.6 M, for example, about 0.9 M, 1.0 M, 1.1 M, 1.2 M, 1.3 M, 1.4 M, or 1.5 M. According to embodiments of the present disclosure, the solvent may be an organic solvent, such as an ester-based solvent, a ketone-based solvent, a carbonate-based solvent, an ether-based solvent, an alkane-based solvent, an amide-based solvent, or a combination thereof. According to embodiments of the present disclosure, the solvent may be 1,2-diethoxyethane, 1,2-dimethoxyethane, 1,2-dibutoxyethane, tetrahydrofuran (THF), 2-methyltetrahydrofuran, dimethylacetamide (DMAc), 1-methyl-2-pyrrolidone (NMP), methyl acetate, ethyl acetate, methyl butyrate, ethyl butyrate, methyl propionate, ethyl propionate, propyl acetate (PA), γ-butyrolactone (GBL), ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), vinylene carbonate, butylene carbonate, dipropyl carbonate, fluoroethylene carbonate, 1,3-propane sultone, or a combination thereof.According to an embodiment of the present disclosure, the lithium salt may be lithium hexafluorophosphate (LiPF), lithium perchlorate (LiClO), lithium bis(fluorosulfonyl)imide (LiN(SOF)) (LiFSI), lithium difluoro(oxalato)borate (LiBF(C0)) (LiDFOB), lithium tetrafluoroborate (LiBF), lithium trifluoromethanesulfonate (LiSOCF), lithium bis(trifluoromethane)sulfonimide (LiN(SOCF)) (LiTFSI), lithium bisperfluoroethaneethanesulfonimide (LiN(SOCFCF)), lithium hexafluoroarsenate (LiAsF), lithium hexafluoroantimonate (LiSbF), lithium tetrachloroaluminate (LiAlCl), lithium tetrachlorogallate (lithium tetrachloride), lithium tetrafluoromethanesulfonate (LiAsF), lithium hexafluoroarsenate (LiAsF), lithium hexafluoroantimonate (LiSbF), lithium tetrachloroaluminate (LiAlCl), lithium tetrachlorogallate (lithium tetrachloride), lithium tetrafluoromethanesulfonate (LiAsF), lithium hexafluoroarsenate (LiAsF), lithium hexafluoroantimonate (LiSbF), lithium tetrachloroaluminate (LiAlCl), lithium tetrachlorogallate (lithium tetrachloride), lithium tetrafluoromethanesulfonate (LiFCF ... tetrachlorogallate (LiGaCl4)), lithium nitrate (LiNO3), tris(trifluoromethanesulfonyl)methyllithium (LiC(SO2CF3)3), lithium thiocyanate hydrate (LiSCN), LiO3SCF2CF3, LiC6F5SO3, LiO2CCF3, lithium fluorosulfonate (LiSO3F), lithium tetrakis(pentafluorophenyl)borate (LiB(C6H5)4), lithium bis(oxalato)borate (LiB(C2O4)2) (LiBOB), or combinations thereof.

[0038] According to embodiments of the present disclosure, the negative electrode 30 may include a negative electrode current collecting layer 32 and a negative electrode active layer 34 disposed on the negative electrode current collecting layer 32, where the negative electrode active layer 34 includes a negative electrode active material. In some embodiments, the negative electrode active layer 34 may further include a binder. The binder may include polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), carboxymethyl cellulose, sodium carboxymethyl cellulose, polyvinylidene fluoride (PVDF), styrene-butadiene copolymer, fluororubber, polyurethane, polyvinylpyrrolidone, poly(ethyl acrylate), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polybutadiene, polyacrylic acid (PAA), or a combination thereof. According to embodiments of the present disclosure, the negative electrode 30 may include the negative electrode current collecting layer 32 and the negative electrode active layer 34. Additionally, according to embodiments of the present disclosure, the negative electrode 30 may include the negative electrode current collecting layer 32.

[0039] According to an embodiment of the present disclosure, in the negative electrode active layer 34, the weight percentage of the negative electrode active material may be about 90 wt % to 99.9 wt % (e.g., 91 wt %, 92 wt %, 93 wt %, 94 wt %, 95 wt %, 96 wt %, 97 wt %, 98 wt %, or 99 wt %), and the weight percentage of the binder may be about 0.1 wt % to 10 wt % (e.g., 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, or 9 wt %), based on the total weight of the negative electrode active material and binder. According to an embodiment of the present disclosure, the weight ratio of the binder to the negative electrode active material in the negative electrode active layer 34 may be 0.1:99.9 to 10:90 (e.g., 1:99, 2:98, 3:97, 4:96, 5:95, 6:94, 7:93, 8:92, or 9:91). According to an embodiment of the present disclosure, the negative electrode active layer 34 may be composed of the binder and the negative electrode active material. According to an embodiment of the present disclosure, the negative electrode current collecting layer 32 may be a conductive carbon substrate, a metal foil, or a metal material having a porous structure, such as carbon cloth, carbon felt, carbon paper, copper foil, nickel foil, aluminum foil, nickel mesh, copper mesh, molybdenum mesh, nickel foam, copper foam, or molybdenum foam. According to an embodiment of the present disclosure, the porosity of the metal material having a porous structure may be about 10% to 99.9% (e.g., 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%).

[0040] According to some embodiments of the present disclosure, the negative electrode active layer 34 of the present disclosure may be disposed between the separator 20 and the negative electrode current collecting layer 32. According to embodiments of the present disclosure, the negative electrode active material may include a carbon material, lithium, a transition metal oxide, a lithium-containing compound, a silicon-containing material, or a combination thereof. According to embodiments of the present disclosure, the carbon material may include metastable phase spherical carbon (MCMB), vapor-grown carbon fiber (VGCF), carbon nanotubes (CNTs), coke, carbon black, graphite, graphene, acetylene black, carbon fiber, or a combination thereof. According to embodiments of the present disclosure, the lithium-containing compound may include LiAl, LiMg, LiZn, LiBi, LiCd, LiSb, LiSi, Li 4.4 Pb, Li 4.4 Sn, LiC6, Li3FeN2, Li 2.6 Co 0.4 N, or Li 2.6 Cu 0.4 According to embodiments of the present disclosure, the silicon-containing material may include carbon-modified silicon oxide, silicon carbide, or pure silicon material. According to embodiments of the present disclosure, the transition metal oxide may include Li4Ti5O 12 Alternatively, TiNb2O may be included.

[0041] According to an embodiment of the present disclosure, as shown in Figure 6, when a battery 100 of the present disclosure includes the positive electrode shown in Figure 2, the battery 100 may further include a metal oxide layer 22 disposed on a separator 20, with the metal oxide layer 22 being disposed between the separator 20 and the positive electrode 10. The combination of the metal oxide layer 22 and the positive electrode 10 of the present disclosure can extend the time during which an internal short circuit occurs in a lithium battery including the positive electrode when the battery is overcharged. Furthermore, when an internal short circuit occurs in a lithium battery including the positive electrode, the release of battery energy can be slowed (i.e., the energy release rate is reduced), thereby improving the safety of the lithium battery during use.

[0042] According to an embodiment of the present disclosure, the metal oxide layer 22 may include a metal oxide powder, such as aluminum oxide, zirconium oxide, zinc oxide, silicon oxide, tin oxide, or a combination thereof. According to an embodiment of the present disclosure, the particle size of the metal oxide powder is not limited and can be freely varied by those skilled in the art. The particle size of the metal oxide powder may be 1 nm to 5 μm, for example, 10 nm, 50 nm, 100 nm, 500 nm, 1 μm, or 3 μm. According to an embodiment of the present disclosure, the metal oxide layer 22 may further include a binder, which may include polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), carboxymethyl cellulose, sodium carboxymethyl cellulose, polyvinylidene fluoride (PVDF), styrene-butadiene copolymer, fluororubber, polyurethane, polyvinylpyrrolidone, poly(ethyl acrylate), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polybutadiene, polyacrylic acid (PAA), or a combination thereof. According to embodiments of the present disclosure, in the metal oxide layer 22, the weight percentage of the metal oxide powder may be about 90 wt % to 99.9 wt % (e.g., 91 wt %, 92 wt %, 93 wt %, 94 wt %, 95 wt %, 96 wt %, 97 wt %, 98 wt %, or 99 wt %), and the weight percentage of the binder may be about 0.1 wt % to 10 wt % (e.g., 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, or 9 wt %), based on the total weight of the metal oxide powder and binder. According to embodiments of the present disclosure, the weight ratio of binder to metal oxide powder in metal oxide layer 22 may be 0.1:99.9 to 10:90 (e.g., 1:99, 2:98, 3:97, 4:96, 5:95, 6:94, 7:93, 8:92, or 9:91). According to embodiments of the present disclosure, metal oxide layer 22 may consist of a binder and a metal oxide powder.

[0043] According to the embodiment of the present disclosure, the thickness of the metal oxide layer 22 is not limited and can be arbitrarily changed by a person skilled in the art. For example, the thickness of the metal oxide layer 22 may be about 1 μm to 10 μm (e.g., about 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, or 8 μm).

[0044]

[0030] In the following, exemplary embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily understand. The concept of the present invention is not limited to the exemplary embodiments shown herein, but can be embodied in various forms. For clarity, descriptions of well-known parts will be omitted, and similar reference numerals will denote similar components throughout. [Example]

[0045] Example 1 Lithium nickel manganese cobalt oxide (chemical structure LiNi 0.6 Mn 0.2 Co 0.2 96 parts by weight of ethylenediamine fluoride (O2) (commercially available from Ningbo Ronbay New Energy Technology Co., Ltd. under trade number NMC622), 2 parts by weight of conductive carbon black (commercially available from Timcal under trade number Super-P), and 2 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under trade number PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a positive electrode active layer slurry. The positive electrode active layer slurry was then coated onto aluminum foil (commercially available from An Chuan Enterprise Co., Ltd., with a thickness of 12 μm) to serve as the positive electrode current collector layer. After drying, a positive electrode active layer (disposed on the positive electrode current collector layer) was obtained (with a thickness of approximately 65 μm and an area weight of approximately 19 mg / cm). 2 The resistance of the resulting positive electrode active layer was measured using a four-point probe resistance meter, and was found to be approximately 0.008 Ω.

[0046] Next, 97 parts by weight of lithium iron manganese phosphate (LMFP) (commercially available from HCM CO., LTD. under the trade name GE), 0.1 parts by weight of conductive carbon black (commercially available from Timcal under the trade name Super-P), and 2.9 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under the trade name PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a lithium iron manganese phosphate slurry. The lithium iron manganese phosphate slurry was then applied onto the positive electrode active layer. After drying, a first layer (disposed on the positive electrode active layer) was obtained (with a thickness of about 18 μm and an area weight of about 4 mg / cm). 2 ) The laminate of the positive electrode current collecting layer, the positive electrode active layer, and the first layer was used as the positive electrode. The resistance of the obtained first layer was measured using a four-point probe resistance meter, and the resistance of the first layer was found to be approximately 480 Ω. After the measurement, the electrical resistance ratio between the first layer and the positive electrode active layer was approximately 6 × 10 4 It was.

[0047] Next, copper foil (available from Chang Chun Group under the trade number BFR-F) (which will serve as the negative electrode) and a polyethylene (PE) separator (available from Asahi Kasei under the trade number N9620) (approximately 16 μm thick) were prepared. The negative electrode, separator, and positive electrode were then arranged in this order (with the first layer of the positive electrode facing the separator) and sealed in an aluminum foil cell (5 mm thick x 60 mm wide x 80 mm long). A liquid electrolyte was then injected into the aluminum foil cell to form a battery. The liquid electrolyte contained LiPF6 and a solvent, which was ethylene carbonate (EC) and diethyl carbonate (DEC), with a volume ratio of EC to DEC of 1:1 and a LiPF6 concentration of 1.1 M.

[0048] The battery was then overcharged at a charge rate of 1C and the events were recorded when the battery was charged to 19V. The results are shown in Table 1.

[0049] Comparative Example 1 A laminate of the positive electrode current collecting layer and the positive electrode active layer of Example 1 was prepared.

[0050] Next, copper foil (available from Chang Chun Group under the trade number BFR-F) (which serves as the negative electrode) and a polyethylene (PE) separator (available from Asahi Kasei under the trade number N9620) (approximately 16 μm thick) were prepared. The negative electrode, separator, and positive electrode were then arranged in this order (with the first layer of the positive electrode facing the separator) and sealed in an aluminum foil cell (5 mm thick x 60 mm wide x 80 mm long). Liquid electrolyte was then poured into the aluminum foil cell to form a battery. The liquid electrolyte contained LiPF6 and a solvent, consisting of ethylene carbonate (EC) and diethyl carbonate (DEC), with a volume ratio of EC to DEC of 1:1 and a LiPF6 concentration of 1.1M.

[0051] The battery was then overcharged at a charge rate of 1C and the events were recorded when the battery was charged to 19V. The results are shown in Table 1.

[0052] [Table 1]

[0053] As shown in Table 1, compared to the battery of Comparative Example 1, when the battery (i.e., the battery of Example 1) uses the positive electrode of the present disclosure (having lithium iron manganese phosphate disposed on the positive electrode active layer), the time it takes to charge the battery to 19 V is extended, and the battery can be maintained at 19 V even during continued charging after charging the battery to 19 V, thereby preventing the battery from exploding.

[0054] Example 2 The positive electrode of Example 1, copper foil (trade number BFR-F, commercially available from Chang Chun Group) (to serve as the negative electrode), and a separator having an aluminum oxide layer (commercially available from BenQ, approximately 18 μm thick, of which the aluminum oxide layer was 2 μm thick) were prepared.

[0055] The negative electrode, separator with an aluminum oxide layer, and positive electrode were then arranged in this order (with the first layer of the positive electrode facing the aluminum oxide layer) and sealed in an aluminum foil cell (5 mm (thickness) × 60 mm (width) × 80 mm (length)). A liquid electrolyte was then poured into the aluminum foil cell to obtain a battery. The liquid electrolyte contained LiPF6 and a solvent, ethylene carbonate (EC) and diethyl carbonate (DEC), with a volume ratio of EC to DEC of 1:1 and a LiPF6 concentration of 1.1 M.

[0056] The battery was then overcharged at a charge rate of 1C and the events were recorded when the battery was charged to 19V, the results of which are shown in Table 2.

[0057] Comparative Example 2 A laminate of a positive electrode current collecting layer and a positive electrode active layer was prepared as in Example 1. A separator having a copper foil (trade number BFR-F, commercially available from Chang Chun Group) (to serve as the negative electrode) and an aluminum oxide layer as in Example 2 was prepared.

[0058] The negative electrode, separator with an aluminum oxide layer, and positive electrode were then arranged in this order (with the first layer of the positive electrode facing the aluminum oxide layer) and sealed in an aluminum foil cell (5 mm (thickness) × 60 mm (width) × 80 mm (length)). A liquid electrolyte was then poured into the aluminum foil cell to obtain a battery. The liquid electrolyte contained LiPF6 and a solvent, ethylene carbonate (EC) and diethyl carbonate (DEC), with a volume ratio of EC to DEC of 1:1 and a LiPF6 concentration of 1.1 M.

[0059] The battery was then overcharged at a charge rate of 1C and the events were recorded when the battery was charged to 19V, the results of which are shown in Table 2.

[0060] [Table 2]

[0061] As shown in Table 2, compared to the battery of Comparative Example 2, when the battery (i.e., the battery of Example 2) uses the positive electrode of the present disclosure (having lithium iron manganese phosphate disposed on the positive electrode active layer), the time it takes to charge the battery to 19 V is extended, and the battery can be maintained at 19 V during continued charging after being charged to 19 V, thereby preventing the battery from exploding.

[0062] Example 3 Lithium nickel manganese cobalt oxide (chemical structure LiNi 0.83~0.85 Mn 0.4~0.5 Co 0.11~0.12 96 parts by weight of conductive carbon black (commercially available from Ningbo Ronbay New Energy Technology Co., Ltd. under trade number NMC811), 2 parts by weight of conductive carbon black (commercially available from Timcal under trade number Super-P), and 2 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under trade number PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a positive electrode active layer slurry. The positive electrode active layer slurry was then coated onto aluminum foil (commercially available from An Chuan Enterprise Co., Ltd., with a thickness of 12 μm) to serve as the positive electrode current collector layer. After drying, a positive electrode active layer (disposed on the positive electrode current collector layer) was obtained (with a thickness of approximately 85 μm and an area weight of approximately 19 mg / cm). 2 The resistance of the resulting positive electrode active layer was measured using a four-point probe resistance meter, and was found to be approximately 0.009 Ω.

[0063] Next, 97 parts by weight of lithium iron manganese phosphate (LMFP) (commercially available from HCM CO., LTD. under the trade name GE), 0.1 parts by weight of conductive carbon black (commercially available from Timcal under the trade name Super-P), and 2.9 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under the trade name PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a lithium iron manganese phosphate slurry. The lithium iron manganese phosphate slurry was then applied onto the positive electrode active layer. After drying, a first layer (disposed on the positive electrode active layer) was obtained (with a thickness of about 18 μm and an area weight of about 4 mg / cm). 2 ) The laminate of the positive electrode current collecting layer, the positive electrode active layer, and the first layer was used as the positive electrode. The resistance of the obtained first layer was measured using a four-point probe resistance meter, and the resistance of the first layer was found to be approximately 90 Ω. After the measurement, the electrical resistance ratio between the first layer and the positive electrode active layer was approximately 1 × 10 4 It was.

[0064] Next, a copper foil (trade number BFR-F, commercially available from Chang Chun Group) (to serve as the negative electrode) and a separator with an aluminum oxide layer (commercially available from BenQ, approximately 18 μm thick, with the aluminum oxide layer being 2 μm thick) were prepared.

[0065] Then, the negative electrode, the separator having the aluminum oxide layer, and the positive electrode were arranged in this order (with the first layer of the positive electrode facing the aluminum oxide layer) and sealed in an aluminum foil cell (size: 5 mm (thickness) × 60 mm (width) × 80 mm (length)), and then a liquid electrolyte (commercially available from Hopax Chemicals Manufacturing Co Ltd. under trade number NDFX2) was injected into the aluminum foil cell to obtain a battery.

[0066] The battery was then overcharged at a charge rate of 1C and the events were recorded when the battery was charged to 6V, the results of which are shown in Table 3.

[0067] Comparative Example 3 A laminate of the positive electrode current collector layer and the positive electrode active layer of Example 3 was prepared. A separator having a copper foil (trade number BER-F, commercially available from Chang Chun Group) (to serve as the negative electrode) and an aluminum oxide layer of Example 3 was prepared.

[0068] Then, the negative electrode, the separator having the aluminum oxide layer, and the positive electrode were arranged in this order (with the first layer of the positive electrode facing the aluminum oxide layer) and sealed in an aluminum foil cell (size: 5 mm (thickness) × 60 mm (width) × 80 mm (length)), and then a liquid electrolyte (commercially available from Hopax Chemicals Manufacturing Co Ltd. under trade number NDFX2) was injected into the aluminum foil cell to obtain a battery.

[0069] The battery was then overcharged at a charge rate of 1C and the events were recorded when the battery was charged to 6V, the results of which are shown in Table 3.

[0070] Example 4 Lithium nickel manganese cobalt oxide (chemical structure LiNi 0.83~0.85 Mn 0.4~0.5 Co 0.11~0.12 96 parts by weight of conductive carbon black (commercially available from Ningbo Ronbay New Energy Technology Co., Ltd. under trade number NMC811), 2 parts by weight of conductive carbon black (commercially available from Timcal under trade number Super-P), and 2 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under trade number PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a positive electrode active layer slurry. The positive electrode active layer slurry was then coated onto aluminum foil (commercially available from An Chuan Enterprise Co., Ltd., with a thickness of 12 μm) to serve as the positive electrode current collector layer. After drying, a positive electrode active layer (disposed on the positive electrode current collector layer) was obtained (with a thickness of approximately 85 μm and an area weight of approximately 19 mg / cm). 2 ).

[0071] Next, 97 parts by weight of lithium iron manganese phosphate (LMFP) (commercially available from HCM CO., LTD. under the trade name GE) and 3 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under the trade name PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a lithium iron manganese phosphate slurry. The lithium iron manganese phosphate slurry was then applied onto the positive electrode active layer. After drying, a first layer (disposed on the positive electrode active layer) was obtained (18 μm thick, area weight approximately 4 mg / cm). 2 )

[0072] 10 mg of stabilized lithium metal particles (commercially available from Livent under the trade designation SLMP) were uniformly dispersed in the first layer. A pressure of 100 gf was then applied to adhere the stabilized lithium metal particles to the first layer, and a second layer (disposed on the first layer) (area weight of about 0.2 mg / cm) was then applied. 2 The stack of the positive electrode current collecting layer, the positive electrode active layer, the first layer, and the second layer constitutes the positive electrode.

[0073] A copper foil (trade number BFR-F, commercially available from Chang Chun Group) (to serve as the negative electrode) and a separator with an aluminum oxide layer (commercially available from BenQ) (approximately 18 μm thick, with the aluminum oxide layer being 2 μm thick) were prepared.

[0074] Then, the negative electrode, the separator having the aluminum oxide layer, and the positive electrode were arranged in this order (with the first layer of the positive electrode facing the aluminum oxide layer), and sealed in an aluminum foil cell (size: 5 mm (thickness) × 60 mm (width) × 80 mm (length)), and then a liquid electrolyte (commercially available from Hopax Chemicals Manufacturing Co. Ltd. under trade number NDFX2) was injected into the aluminum foil cell to obtain a battery.

[0075] The battery was then overcharged at a charge rate of 1C and the events were recorded when the battery was charged to 6V, the results of which are shown in Table 3.

[0076] [Table 3]

[0077] As shown in Table 3, when a battery (i.e., the battery of Example 3) uses a positive electrode of the present disclosure (having a lithium iron manganese phosphate layer disposed on the positive electrode active layer), compared to the battery of Comparative Example 3, the time required to charge the battery to 6 V is extended, and the battery can be maintained at 6 V even during continued charging after charging to 6 V, thereby preventing battery explosion. Also, when a battery (i.e., the battery of Example 4) uses a positive electrode of the present disclosure (having a lithium iron manganese phosphate layer and a stabilized lithium metal particle layer disposed on the positive electrode active layer), the time required to charge the battery to 6 V is extended, and the battery can be maintained at 6 V even during continued charging after charging to 6 V, thereby preventing battery explosion.

[0078] Comparative Example 4 A stack of the positive electrode current collecting layer and the positive electrode active layer of Example 3 was prepared.

[0079] 10 mg of stabilized lithium metal particles (commercially available from Livent under the trade designation SLMP) were uniformly dispersed on the positive electrode active layer. A pressure of 100 gf was then applied to adhere the stabilized lithium metal particles to the positive electrode active layer, resulting in a stabilized lithium metal particle layer (disposed on the positive electrode active layer) (area weight of about 0.2 mg / cm). 2 The stack of the positive electrode current collecting layer, the positive electrode active layer, and the stabilized lithium metal particle layer constitutes the positive electrode.

[0080] A copper foil (trade number BFR-F, commercially available from Chang Chun Group) (as the negative electrode) and a separator having an aluminum oxide layer as in Example 3 were prepared.

[0081] The negative electrode, the separator having the aluminum oxide layer, and the positive electrode were then arranged in this order (with the stabilized lithium metal particle layer of the positive electrode facing the aluminum oxide layer) and sealed in an aluminum foil cell (size: 5 mm (thickness) × 60 mm (width) × 80 mm (length)), and then a liquid electrolyte (commercially available from Hopax Chemicals Manufacturing Co Ltd. under trade number NDFX2) was injected into the aluminum foil cell to obtain a battery.

[0082] The discharge specific capacity in the first charge / discharge cycle of the batteries of Examples 3 and 4 and Comparative Examples 3 and 4 was measured at a charge rate and discharge rate of 0.1 C / 0.1 C (4.5 V to 3 V). The results are shown in Table 4.

[0083] [Table 4]

[0084] As shown in Table 4, the battery using the positive electrode of the present disclosure (having a lithium iron manganese phosphate layer disposed on the positive electrode active layer) (i.e., the battery of Example 3) exhibits sufficient discharge specific capacity. Furthermore, compared to the battery of Comparative Example 3, the battery of Comparative Example 4 exhibits a lower discharge specific capacity when the stabilized lithium metal particle layer is in direct contact with the positive electrode active layer. Compared to the battery of Comparative Example 4, the battery of Example 4 uses the positive electrode of the present disclosure (having a lithium iron manganese phosphate layer and a stabilized lithium metal particle layer disposed on the positive electrode active layer), and therefore the battery of Example 4 has an increased discharge specific capacity.

[0085] Example 5 Lithium nickel manganese cobalt oxide (chemical structure LiNi 0.6 Mn 0.2 Co 0.296 parts by weight of conductive carbon black (commercially available from Ningbo Ronbay New Energy Technology Co., Ltd. under trade number NMC622), 2 parts by weight of conductive carbon black (commercially available from Timcal under trade number Super-P), and 2 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under trade number PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a positive electrode active layer slurry. The positive electrode active layer slurry was then coated onto aluminum foil (commercially available from An Chuan Enterprise Co., Ltd., with a thickness of 12 μm) to serve as the positive electrode current collector layer. After drying, a positive electrode active layer (disposed on the positive electrode current collector layer) was obtained (with a thickness of approximately 65 μm and an area weight of approximately 19 mg / cm). 2 The resistance of the resulting positive electrode active layer was measured using a four-point probe resistance meter, and was found to be approximately 0.008 Ω.

[0086] Next, 97 parts by weight of lithium iron manganese phosphate (LMFP) (commercially available from HCM CO., LTD. under the trade name GE) and 3 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under the trade name PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a lithium iron manganese phosphate slurry. The lithium iron manganese phosphate slurry was then applied onto the positive electrode active layer. After drying, a first layer (disposed on the positive electrode active layer) was obtained (with a thickness of about 18 μm and an area weight of about 2 mg / cm). 2 ) The laminate of the positive electrode current collecting layer, the positive electrode active layer, and the first layer was used as the positive electrode. The resistance of the obtained first layer was measured using a four-point probe resistance meter, and the resistance of the first layer was found to be approximately 313 Ω. After the measurement, the electrical resistance ratio between the first layer and the positive electrode active layer was approximately 3.9 × 10 4 It was.

[0087] Next, copper foil (available from Chang Chun Group under the trade number BFR-F) (which will serve as the negative electrode) and a polyethylene (PE) separator (available from Asahi Kasei under the trade number N9620) (approximately 16 μm thick) were prepared. The negative electrode, the separator with an aluminum oxide layer, and the positive electrode were then arranged in this order (with the first layer of the positive electrode facing the separator) and sealed in an aluminum foil cell (5 mm thick x 60 mm wide x 80 mm long). A liquid electrolyte was then poured into the aluminum foil cell to form a battery. The liquid electrolyte contained LiPF6 and a solvent, which was ethylene carbonate (EC) and diethyl carbonate (DEC), with a volume ratio of EC to DEC of 1:1 and a LiPF6 concentration of 1.1 M.

[0088] The battery was then overcharged at a charge rate of 1C and the events were recorded when the battery was charged to 19V, the results of which are shown in Table 5.

[0089] Example 6 Lithium nickel manganese cobalt oxide (chemical structure LiNi 0.6 Mn 0.2 Co 0.2 96 parts by weight of conductive carbon black (commercially available from Ningbo Ronbay New Energy Technology Co., Ltd. under trade number NMC622), 2 parts by weight of conductive carbon black (commercially available from Timcal under trade number Super-P), and 2 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under trade number PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a positive electrode active layer slurry. The positive electrode active layer slurry was then coated onto aluminum foil (commercially available from An Chuan Enterprise Co., Ltd., with a thickness of 12 μm) to serve as the positive electrode current collector layer. After drying, a positive electrode active layer (disposed on the positive electrode current collector layer) was obtained (with a thickness of approximately 65 μm and an area weight of approximately 19 mg / cm). 2The resistance of the resulting positive electrode active layer was measured using a four-point probe resistance meter, and was found to be approximately 0.008 Ω.

[0090] Next, 96.5 parts by weight of lithium iron manganese phosphate (LMFP) (commercially available from HCM CO., LTD. under the trade name GE), 0.5 parts by weight of VGFC, and 3 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under the trade name PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a lithium iron manganese phosphate slurry. The lithium iron manganese phosphate slurry was then applied onto the positive electrode active layer. After drying, a first layer (disposed on the positive electrode active layer) was obtained (with a thickness of about 18 μm and an area weight of about 2 mg / cm). 2 ) The laminate of the positive electrode current collecting layer, the positive electrode active layer, and the first layer was used as the positive electrode. The resistance of the obtained first layer was measured using a four-point probe resistance meter, and the resistance of the first layer was found to be approximately 92 Ω. After the measurement, the electrical resistance ratio between the first layer and the positive electrode active layer was approximately 1.1 × 10 4 It was.

[0091] Next, copper foil (available from Chang Chun Group under the trade number BFR-F) (which will serve as the negative electrode) and a polyethylene (PE) separator (available from Asahi Kasei under the trade number N9620) (approximately 16 μm thick) were prepared. The negative electrode, the separator with an aluminum oxide layer, and the positive electrode were then arranged in this order (with the first layer of the positive electrode facing the separator) and sealed in an aluminum foil cell (5 mm thick x 60 mm wide x 80 mm long). A liquid electrolyte was then injected into the aluminum foil cell to form a battery. The liquid electrolyte contained LiPF6 and a solvent, which was ethylene carbonate (EC) and diethyl carbonate (DEC), with a volume ratio of EC to DEC of 1:1 and a LiPF6 concentration of 1.1 M.

[0092] The battery was then overcharged at a charge rate of 1C and the events were recorded when the battery was charged to 19V, the results of which are shown in Table 5.

[0093] Comparative Example 5 Lithium nickel manganese cobalt oxide (chemical structure LiNi 0.6 Mn 0.2 Co 0.2 96 parts by weight of conductive carbon black (commercially available from Ningbo Ronbay New Energy Technology Co., Ltd. under trade number NMC622), 2 parts by weight of conductive carbon black (commercially available from Timcal under trade number Super-P), and 2 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under trade number PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a positive electrode active layer slurry. The positive electrode active layer slurry was then coated onto aluminum foil (commercially available from An Chuan Enterprise Co., Ltd., with a thickness of 12 μm) to serve as the positive electrode current collector layer. After drying, a positive electrode active layer (disposed on the positive electrode current collector layer) was obtained (with a thickness of approximately 65 μm and an area weight of approximately 19 mg / cm). 2 The resistance of the resulting positive electrode active layer was measured using a four-point probe resistance meter, and was found to be approximately 0.008 Ω.

[0094] Next, 96.5 parts by weight of lithium iron manganese phosphate (LMFP) (commercially available from HCM CO., LTD. under the trade name GE), 0.5 parts by weight of VGCF, 0.1 parts by weight of carbon nanotubes (commercially available from Beijing Cnano Technology under the trade name CNT), and 2.9 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under the trade name PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a lithium iron manganese phosphate slurry. The lithium iron manganese phosphate slurry was then applied onto the positive electrode active layer. After drying, a first layer (disposed on the positive electrode active layer) was obtained (with a thickness of about 10 μm and an area weight of about 2 mg / cm). 2) The laminate of the positive electrode current collecting layer, positive electrode active layer, and first layer constituted the positive electrode. The resistance of the resulting first layer was measured using a four-point probe resistance meter, and was found to be approximately 0.0196 Ω. After the measurement, the electrical resistance ratio between the first layer and the positive electrode active layer was approximately 2.5.

[0095] Next, copper foil (available from Chang Chun Group under the trade number BFR-F) (which will serve as the negative electrode) and a polyethylene (PE) separator (available from Asahi Kasei under the trade number N9620) (approximately 16 μm thick) were prepared. The negative electrode, the separator with an aluminum oxide layer, and the positive electrode were then arranged in this order (with the first layer of the positive electrode facing the separator) and sealed in an aluminum foil cell (5 mm thick x 60 mm wide x 80 mm long). A liquid electrolyte was then injected into the aluminum foil cell to form a battery. The liquid electrolyte contained LiPF6 and a solvent, which was ethylene carbonate (EC) and diethyl carbonate (DEC), with a volume ratio of EC to DEC of 1:1 and a LiPF6 concentration of 1.1 M.

[0096] The battery was then overcharged at a charge rate of 1C and the events were recorded when the battery was charged to 19V, the results of which are shown in Table 5.

[0097] [Table 5]

[0098] As shown in Table 5, compared to the battery of Comparative Example 5, when the batteries (i.e., the batteries of Examples 5 and 6) used the positive electrode of the present disclosure (having a lithium iron manganese phosphate layer disposed on the positive electrode active layer), the time required to charge the battery to 19 V was extended, and the battery could be maintained at 19 V even during continued charging after being charged to 19 V, thereby preventing battery explosion.

[0099] Example 7 96.3 parts by weight of SiO / C (a mixture of silicon oxide and carbon) (available from Kaijin New Energy Technology Co., Ltd. under the trade name KYX-2), 0.3 parts by weight of conductive carbon black (available from Timcal under the trade name Super-P), 1.5 parts by weight of styrene butadiene rubber (SBR) (available from JSR), 1.3 parts by weight of carboxymethyl cellulose (CMC) (available from Daicel Chemical Industries under the trade name CMC-2200), and 0.6 parts by weight of carbon nanotubes (available from OCSiAl under the trade name TUBALL®) were mixed and uniformly dispersed in deionized water to obtain a negative electrode active layer slurry. The negative electrode active layer slurry was then coated onto a copper foil (available from Chang Chun Group under the trade name BFR-F) (approximately 12 μm thick). After drying, a negative electrode was obtained.

[0100] The positive electrode of Example 3 and a separator having an aluminum oxide layer were prepared.

[0101] The negative electrode, the separator with the aluminum oxide layer, and the positive electrode were then arranged in this order (with the first layer of the positive electrode facing the aluminum oxide layer) and sealed in an aluminum foil cell (5 mm (thickness) × 60 mm (width) × 80 mm (length)), and then a liquid electrolyte (commercially available from Formosa Plastics Corporation under trade number LD88) was injected into the aluminum foil cell to obtain a battery.

[0102] Example 8 The negative electrode of Example 7, the positive electrode of Example 4, and the separator having the aluminum oxide layer of Example 3 were prepared.

[0103] The negative electrode, the separator with the aluminum oxide layer, and the positive electrode were then arranged in this order (with the second layer of the positive electrode facing the aluminum oxide layer) and sealed in an aluminum foil cell (5 mm (thickness) × 60 mm (width) × 80 mm (length)), and then a liquid electrolyte (commercially available from Formosa Plastics Corporation under trade number LD88) was injected into the aluminum foil cell to obtain a battery.

[0104] The discharge specific capacity in the first charge / discharge cycle of the batteries of Examples 7 and 8 was measured at a charge rate and discharge rate of 0.1 C / 0.1 C (4.2 V to 2.8 V). The results are shown in Table 6.

[0105] [Table 6]

[0106] As shown in Table 6, the battery (i.e., the battery of Example 8) uses a positive electrode of the present disclosure (having a lithium iron manganese phosphate layer and a stabilized lithium metal particle layer disposed on a positive electrode active layer), and therefore has an increased discharge specific capacity.

[0107] Next, the capacity retention rates of the batteries of Examples 7 and 8 were measured, and the results are shown in Table 7. The capacity retention rates were measured by measuring the discharge specific capacity in the first charge / discharge cycle and the discharge specific capacity in the 50th charge / discharge cycle at a charge rate and discharge rate of 0.1 C / 0.1 C and at 25°C.

[0108] [Table 7]

[0109] As shown in Tables 6 and 7, the battery using the positive electrode of the present disclosure has an increased discharge specific capacity, provided that the capacity retention rate does not decrease.

[0110] Example 9 Lithium nickel manganese cobalt oxide (chemical structure LiNi 0.6 Mn 0.2 Co 0.2 96 parts by weight of conductive carbon black (commercially available from Ningbo Ronbay New Energy Technology Co., Ltd. under trade number NMC622), 2 parts by weight of conductive carbon black (commercially available from Timcal under trade number Super-P), and 2 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under trade number PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a positive electrode active layer slurry. The positive electrode active layer slurry was then coated onto aluminum foil (commercially available from An Chuan Enterprise Co., Ltd., with a thickness of 12 μm) to serve as the positive electrode current collector layer. After drying, a positive electrode active layer (disposed on the positive electrode current collector layer) was obtained (with a thickness of approximately 65 μm and an area weight of approximately 19 mg / cm). 2 The resistance of the resulting positive electrode active layer was measured using a four-point probe resistance meter, and was found to be approximately 0.008 Ω.

[0111] Next, 96.5 parts by weight of lithium iron manganese phosphate (LMFP) (commercially available from HCM CO., LTD. under the trade name GE), 0.5 parts by weight of VGCF, 0.07 parts by weight of carbon nanotubes (commercially available from Beijing Cnano Technology under the trade name CNT), and 2.93 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under the trade name PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a lithium iron manganese phosphate slurry. The lithium iron manganese phosphate slurry was then applied onto the positive electrode active layer. After drying, a first layer (disposed on the positive electrode active layer) was obtained (with a thickness of about 18 μm and an area weight of about 2 mg / cm). 2) The laminate of the positive electrode current collecting layer, positive electrode active layer, and first layer was used as the positive electrode. The resistance of the resulting first layer was measured using a four-point probe resistance meter, and was found to be approximately 2.418 Ω. After the measurement, the electrical resistance ratio between the first layer and the positive electrode active layer was approximately 302.

[0112] Next, copper foil (available from Chang Chun Group under the trade number BFR-F) (which will serve as the negative electrode) and a polyethylene (PE) separator (available from Asahi Kasei under the trade number N9620) (approximately 16 μm thick) were prepared. The negative electrode, the separator with an aluminum oxide layer, and the positive electrode were then arranged in this order (with the first layer of the positive electrode facing the separator) and sealed in an aluminum foil cell (5 mm thick x 60 mm wide x 80 mm long). A liquid electrolyte was then injected into the aluminum foil cell to form a battery. The liquid electrolyte contained LiPF6 and a solvent, which was ethylene carbonate (EC) and diethyl carbonate (DEC), with a volume ratio of EC to DEC of 1:1 and a LiPF6 concentration of 1.1 M.

[0113] The battery was then overcharged at a charge rate of 1C and the events were recorded when the battery was charged to 19V, the results of which are shown in Table 8.

[0114] Example 10 Lithium nickel manganese cobalt oxide (chemical structure LiNi 0.6 Mn 0.2 Co 0.296 parts by weight of conductive carbon black (commercially available from Ningbo Ronbay New Energy Technology Co., Ltd. under trade number NMC622), 2 parts by weight of conductive carbon black (commercially available from Timcal under trade number Super-P), and 2 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under trade number PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a positive electrode active layer slurry. The positive electrode active layer slurry was then coated onto aluminum foil (commercially available from An Chuan Enterprise Co., Ltd., with a thickness of 12 μm) to serve as the positive electrode current collector layer. After drying, a positive electrode active layer (disposed on the positive electrode current collector layer) was obtained (with a thickness of approximately 65 μm and an area weight of approximately 19 mg / cm). 2 The resistance of the resulting positive electrode active layer was measured using a four-point probe resistance meter, and was found to be approximately 0.008 Ω.

[0115] Next, 96 parts by weight of lithium iron manganese phosphate (LMFP) (commercially available from HCM CO., LTD. under the trade name GE) and 4 parts by weight of polyvinylidene fluoride (PVDF) binder (commercially available from Solvay under the trade name PVDF-5130) were uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to obtain a lithium iron manganese phosphate slurry. The lithium iron manganese phosphate slurry was then applied onto the positive electrode active layer. After drying, a first layer (disposed on the positive electrode active layer) was obtained (with a thickness of about 18 μm and an area weight of about 2 mg / cm). 2 ) The laminate of the positive electrode current collecting layer, the positive electrode active layer, and the first layer was used as the positive electrode. The resistance of the obtained first layer was measured using a four-point probe resistance meter, and the resistance of the first layer was found to be approximately 5750 Ω. After the measurement, the electrical resistance ratio between the first layer and the positive electrode active layer was approximately 7.2 × 10 5 It was.

[0116] Next, copper foil (available from Chang Chun Group under the trade number BFR-F) (which will serve as the negative electrode) and a polyethylene (PE) separator (available from Asahi Kasei under the trade number N9620) (approximately 16 μm thick) were prepared. The negative electrode, the separator with an aluminum oxide layer, and the positive electrode were then arranged in this order (with the first layer of the positive electrode facing the separator) and sealed in an aluminum foil cell (5 mm thick x 60 mm wide x 80 mm long). A liquid electrolyte was then injected into the aluminum foil cell to form a battery. The liquid electrolyte contained LiPF6 and a solvent, which was ethylene carbonate (EC) and diethyl carbonate (DEC), with a volume ratio of EC to DEC of 1:1 and a LiPF6 concentration of 1.1 M.

[0117] The battery was then overcharged at a charge rate of 1C and the events were recorded when the battery was charged to 19V, the results of which are shown in Table 8.

[0118] [Table 8]

[0119] Therefore, the specific composition and structure of the positive electrode of the present disclosure can extend the time until an internal short circuit occurs in a lithium battery including the positive electrode. In addition, when a lithium battery including the positive electrode experiences an internal short circuit, the battery energy release can be slowed down (i.e., the energy release rate is reduced), thereby improving the safety of the lithium battery during use. Furthermore, a lithium battery using the positive electrode (having the specific composition and structure) of the present disclosure can increase the discharge specific capacity, provided that the capacity retention rate is not reduced.

[0120] While the present invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment. Rather, it is intended to cover various modifications and similar arrangements (which would be apparent to those skilled in the art). The scope of the appended claims, therefore, should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. [Explanation of symbols]

[0121] 10...Positive electrode 12...Cathode active layer 14. First layer 16...Positive electrode current collecting layer 18...Second layer 20. Separator 22. Metal oxide layer 30...Negative electrode 32 Negative electrode current collecting layer 34...Negative electrode active layer 40...liquid electrolyte 100...battery

Claims

1. A positive electrode, a positive electrode active layer; a first layer disposed on the positive electrode active layer; Including, the positive electrode active layer includes a positive electrode active material and a conductive additive, and the weight ratio of the conductive additive to the positive electrode active material is 1:99 to 5:95; the first layer contains a lithium iron phosphorus-containing oxide and a first binder, and the electrical resistance ratio between the first layer and the positive electrode active layer is 100 or more; the positive electrode active layer is disposed between the first layer and the positive electrode current collecting layer.

2. 10. The positive electrode of claim 1, wherein the lithium iron phosphorus-containing oxide is lithium iron manganese phosphate, lithium iron phosphate, or a combination thereof.

3. 2. The positive electrode of claim 1, wherein a weight ratio of the first binder to the lithium iron phosphorus oxide is from 1:99 to 5:

95.

4. 2. The positive electrode of claim 1, wherein the first layer further comprises a first inorganic powder, and a weight ratio of the first inorganic powder to the lithium iron phosphorus-containing oxide is from 0.1:99.9 to 1:

99.

5. 5. The positive electrode of claim 4, wherein the first inorganic powder is a conductive powder, a first metal oxide, or a combination thereof.

6. 6. The positive electrode of claim 5, wherein the conductive powder is a metal, an alloy of the metal, conductive carbon black, conductive graphite, a fluorocarbon, reduced graphene, nitrogen-doped graphite, nitrogen-doped graphene, carbon fiber, carbon nanotubes, or a combination thereof, and the metal is zirconium, chromium, molybdenum, tungsten, manganese, iron, osmium, cobalt, nickel, palladium, platinum, copper, silver, gold, zinc, indium, tin, lead, or aluminum.

7. 6. The positive electrode of claim 5, wherein the first metal oxide is aluminum oxide, zirconium oxide, zinc oxide, silicon oxide, tin oxide, or a combination thereof.

8. further comprising a second layer disposed on the first layer; 10. The positive electrode of claim 1, wherein the second layer comprises a second inorganic powder, the second inorganic powder being a second metal oxide, stabilized lithium metal particles, or a combination thereof.

9. 9. The positive electrode of claim 8, wherein the second metal oxide is aluminum oxide, zirconium oxide, zinc oxide, silicon oxide, tin oxide, or a combination thereof.

10. 9. The positive electrode of claim 8, wherein the second layer further comprises a second binder, and a weight ratio of the second binder to the second inorganic powder is from 0.1:99.9 to 10:

90.

11. A positive electrode according to any one of claims 1 to 10; A separator; a negative electrode separated from the positive electrode by the separator; Including batteries.

12. 12. The battery of claim 11, further comprising a liquid electrolyte disposed between the positive electrode and the negative electrode.

13. 12. The battery of claim 11, further comprising a metal oxide layer disposed on the separator and between the separator and the positive electrode.

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