Composite positive electrode containing coated carbon fiber and all-solid-state battery equipped therewith

Abstract

A cathode composite layer for an all-solid-state battery is disclosed, which comprises particles of a cathode active material (CAM), a solid electrolyte (SE), and conductive carbon fibers coated with an oxide material. In one embodiment, the present disclosure provides an all-solid-state battery including the cathode composite layer, which has increased capacity and cycle stability due to reduced SE degradation.

Description

Description of related applications

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 389383, filed on 15 July 2022, and U.S. Provisional Patent Application No. 63 / 350665, filed on 9 June 2022, the entire contents of which are incorporated herein by reference. [Technical Field]

[0002] This disclosure relates to a cathode layer or cathode composite layer for all-solid-state batteries. [Background technology]

[0003] All-solid-state batteries (ASSBs) are considered promising candidates for future energy storage devices because they allow the use of lithium metal as the negative electrode material and would result in higher specific energy compared to conventional lithium-ion batteries based on organic liquid electrolytes. Thiophosphate-based solid electrolytes (SEs) appear particularly promising due to their high ionic conductivity, good mechanical compatibility, and relatively low cost. In general, the insufficient thermodynamic stability, chemomechanical bonding, and interfacial dynamics of SEs are the remaining major challenges. In cathode composites, side reactions include a) decomposition at the current collector / SE interface at high potential, b) reactions between the cathode active material (CAM) and SE that produce a resistive interfacial layer, and c) decomposition reactions at the carbon / SE interface if carbon conductive additives are used. Excessive decomposition of SE leads to Li in the cathode layer. + This can reduce mobility and lead to a decline in capacity over time.

[0004] Composite cathodes containing carbon fibers (CF), such as vapor-grown carbon fibers (VGCF), result in higher initial capacity compared to the corresponding ASSB without CF, because more CAM particles are electrically connected, increasing CAM utilization. However, the initial capacity is not maintained, and a rapid capacity decline is observed during cell cycling due to the rate of SE decomposition (from both the CAM / SE and / or CF / SE interfaces). When the potential is outside the potential stability range of SE, for example, LPS(Li7P3S 11Regarding the electrolyte, if the voltage is higher than 2.1V, the sulfide SE will decompose at the CAM / SE and / or CF / SE interface.

[0005] To minimize the effects of SE decomposition, it is extremely important to reduce SE decomposition in the positive electrode composite layer, especially in layers with a high CAM content, for example, 86% by mass or more, and a low SE content, for example, 14% by mass or less.

[0006] Patent Document 1 describes vapor-grown carbon fiber (VGCF) coated with an electrical insulating material such as boron nitride as a thermally conductive electrical insulating filler. However, the resistivity of the coated VGCF disclosed therein is 10 × 10 3 The resistance is greater than Ω·cm, which can block electrical connection paths required for the electrode layer.

[0007] Patent Document 2 discloses an all-solid-state battery that uses carbon fiber as a conductive agent in the CAM layer to improve initial capacity by increasing the utilization of CAM through an increased electron conduction path. Patent Document 3 discloses an all-solid-state battery that uses a conductive carbon additive in the positive electrode layer. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] U.S. Patent No. 7150911B2 [Patent Document 2] U.S. Patent Application Publication No. 2015 / 0228966A1 [Patent Document 3] U.S. Patent No. 9219271B2 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] However, in none of these cases is the coating carbon material disclosed. SE decomposition remains a problem. [Means for solving the problem]

[0010] In one embodiment, the disclosure relates to CAM particles, a sulfide solid electrolyte, and an oxide material (e.g., Li3B 11 O 18 The present disclosure provides a positive electrode layer comprising carbon fibers (CF) coated with CAM, wherein CAM particles electrically contact the CF, for example, during pressurization in manufacturing. In one embodiment, the present disclosure provides an all-solid-state battery comprising the positive electrode layer. In one embodiment, the ASSB has increased capacity and cycle stability due to reduced SE decomposition at the VGCF / SE interface. [Brief explanation of the drawing]

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0012] In one embodiment, the present disclosure provides a cathode composite layer comprising particles (1) of a cathode active material (CAM), a sulfide-based solid electrolyte (2), and carbon fibers (3) coated with an oxide material (4). In one embodiment, a typical structure is shown in FIG. 1.

[0013] In one embodiment, the sulfide solid electrolyte used in the present disclosure contains Li and S, and any sulfide solid electrolyte may be used as long as it has a desired lithium ion conductivity. The sulfide solid electrolyte may be any of a crystalline material, a glass ceramic, and a glass. Examples of sulfide solid electrolytes include Li2S - P2S5, Li2S - P2S5 - LiHa (where "Ha" is one or more halogen elements), Li2S - P2S5 - P2O5, Li2S - Li3PO4 - P2S5, Li3PS4, Li4P2S6, Li 10 GeP2S 12 、Li 3.25 Ge 0.25 P 0.75 S4、Li7P3S 11 、Li 3.25 P 0.95 S4、およびLi 7-x PS 6-x Ha x(The argyrodite-type solid electrolyte, where "Ha" is one or more halogen elements and 0.2 < x < 1.8) can be mentioned. The concentration in the positive electrode layer is between 1% by mass and 30% by mass.

[0014] In one embodiment, the conductive carbon fibers include, without limitation, vapor-grown carbon fibers (VGCF), carbon nanotubes (CNT), multi-walled carbon nanotubes (MWCNT), carbon nanofibers, and graphite fibers. The CF has a BET measurement specific surface area between 1 and 600 m 2 / g and an electrical resistance of 0.5 Ω·cm or less. In one embodiment, the fibers have a concentration between 0.01% by mass and 5% by mass in the positive electrode layer.

[0015] In one embodiment, the oxide material is an electrical insulating material. In one embodiment, the oxide material is an inorganic oxide material. In one embodiment, the oxide material contains Li, a second element, and a third element. In one embodiment, the second element is one or more elements from Groups 15 and 16 of the periodic table such as O, N, S, P, etc. In one embodiment, the third element is one or more elements from Groups 13 and 14 of the periodic table such as B, C, Al, Si, Ga, and Ge or a transition metal. In one embodiment, the oxide material is an oxide containing Li, B, and one or two or more elements selected from the group consisting of, for example, B, Nb, Ti, Zr, Ta, Zn, W, and Al. In one embodiment, the oxide material includes, without limitation, lithium borate, alumina, lithium zirconate (Li2ZrO3), LiNbO3, Li4SiO4, Li3PO4, Li2SiO3, LiPO3, Li2SO4, Li2WO4, Li2MoO4, LiAlO2, Li2TiO3, Li4Ti5O 12 , or an inorganic oxide material containing its composite oxide. In one embodiment, the lithium borate includes, without limitation, Li3B 11 O 18 , Li3BO3, Li4B2O5, Li6B4O9, LiBO2, Li2B4O7, Li3B7O 12Examples include LiB3O5. In one embodiment, the inorganic oxide is any other material having a wide potential window of stability, for example, from 1.9V to 5.0V. For example, the inorganic oxide material is Li / Li + It has a stable potential window of at least 1.5V. In one embodiment, the inorganic oxide material is Li / Li + It has a stable potential window of at least 2.0V. In one embodiment, the inorganic oxide material is Li / Li + It has a stable potential window of at least 2.5V. In one embodiment, the inorganic oxide material is Li / Li + It has a stable potential window of at least 3.0V. In one embodiment, the inorganic oxide material is Li / Li + It has a stable potential window of at least 4.0V. In one embodiment, the inorganic oxide material is Li / Li + It has a stable potential window of at least 4.5V. In one embodiment, the inorganic oxide material is Li / Li + It has a stable potential window of at least 5.1V.

[0016] In one embodiment, the positive electrode composite layer is sandwiched between the positive electrode current collector and the solid electrolyte layer. In one embodiment, the positive electrode composite layer is sandwiched between the SE layer and the current collector, respectively, and lithium ions (Li + ) and electrons (e - ) Includes a cathode active material (CAM) that requires both connectivity and Li + Connectivity is mainly provided by small particles of sulfide-based SE in the positive electrode composite mixture, e - Connectivity is primarily provided by CF. This sulfide-based SE (such as LPS) has high Li + They have conductivity. However, they generally have Li / Li at the interfaces of CAM / SE, CF / SE, and current collector / SE. + It decomposes at potentials lower than 1.7V or higher than 2.1V. The decomposition byproduct is generally lower Li +It possesses conductivity, which, conversely, requires a higher proportion of SE in the positive electrode composite layer and a lower proportion of CAM. Therefore, decomposition narrows the battery operating voltage window and hinders the ability to create high-energy-density batteries.

[0017] In one embodiment, the disclosure discloses carbon fibers coated with an oxide material layer or coating for a positive electrode composite layer. In one embodiment, the coating is Li / Li + In contrast, Li3B has a wide voltage stability window of 1.9 to 4.7V. 11 O 18 This disclosure has found that the thickness of the oxide material layer is very important. A thick coating may completely block the electron conduction pathway (essential for enabling the operation of a solid-state battery). A thin coating may not make any difference compared to uncoated carbon fibers and cannot reduce decomposition. On the other hand, the coating has a specific thickness to provide certain electrical insulation and thereby reduce SE decomposition at the CF / SE interface. In one embodiment, the thickness is 1 nm or more. In one embodiment, the thickness is 2 nm or more. In one embodiment, the thickness is 5 nm or more. In one embodiment, the thickness is 10 nm or more. In one embodiment, the minimum thickness varies depending on several factors such as the composition of the coating, its inherent properties, and the interface between the coating and CF. On the other hand, the coating should not be too thick and should not be used for battery formation (5000 lbs / in 2It is penetrated by hard CAM particles under pressure (approximately 34.5 MPa), thereby having a thickness t that is thin enough to electrically contact the CAM particles and VGCF. In one embodiment, the thickness is 200 nm or less. In one embodiment, the thickness is 150 nm or less. In one embodiment, the thickness is 100 nm or less. In one embodiment, the thickness is 80 nm or less. In one embodiment, the thickness is 50 nm or less. In one embodiment, the thickness is 30 nm or less. In one embodiment, the maximum thickness varies depending on several factors such as the composition of the coating, its inherent properties, and the interface between the coating and CF. In one embodiment, the cathode composite layer disclosed herein significantly reduces SE decomposition and improves cycle lifetime stability while achieving high initial specific capacity with near 100% CAM utilization. In one embodiment, the coating has a thickness of 1 to 5 nm. In one embodiment, the coating has a thickness of 1 to 20 nm. In one embodiment, the coating has a thickness of 1 to 50 nm. In one embodiment, the coating has a thickness of 1 to 80 nm. In one embodiment, the coating has a thickness of 1 to 100 nm. This disclosure will be better understood by referring to the details of the experiments described below, but it will be readily apparent to those skilled in the art that the specific experiments described are for illustrative purposes only and are not intended to limit this disclosure as defined by the claims that follow.

[0018] In one embodiment, an oxide material can transport lithium ions in a cathode composite layer. While not intended to be bound by any particular theory, lithium ion conductivity is attributed to defects in the crystalline structure of the inorganic oxide and the relatively small activation energy required for the ion transfer process. (Islam, M. et al 2012 J. Phys.: Condens. Matter 24 203201).

[0019] In one embodiment, the disclosure provides a composite layer as a positive electrode for an all-solid-state battery, comprising particles of a positive electrode active material (CAM), a solid electrolyte, and carbon fibers coated with an oxide material. In one embodiment, the oxide material is an electrical insulating material.

[0020] In one embodiment, the oxide material coated on the carbon fiber has a thickness of 1 to 80 nm.

[0021] In one embodiment, the oxide material coated on the carbon fiber has a thickness of 2 to 50 nm. In several embodiments, the oxide material coated on the carbon fiber has a thickness of 1 nm to 100 nm, 1 nm to 90 nm, 1 nm to 80 nm, 1 nm to 70 nm, 1 nm to 60 nm, 1 nm to 50 nm, 1 nm to 40 nm, 1 nm to 30 nm, 1 nm to 25 nm, 1 nm to 20 nm, 1 nm to 15 nm, 1 nm to 10 nm, 2 nm to 100 nm, 2 nm to 90 nm, 2 nm to 80 nm, 2 nm to 70 nm, 2 nm to 60 nm, 2 nm to 50 nm, 2 nm to 40 nm, 2 nm to 30 nm, 2 nm to 25 nm, 2 nm to 20 nm, 2 nm to 15 nm, 2 nm to 10 nm, 5 The thickness has ranges from nm to 100 nm, 5 nm to 90 nm, 5 nm to 80 nm, 5 nm to 70 nm, 5 nm to 60 nm, 5 nm to 50 nm, 5 nm to 40 nm, 5 nm to 30 nm, 5 nm to 25 nm, 5 nm to 20 nm, 5 nm to 15 nm, 5 nm to 10 nm, 10 nm to 100 nm, 10 nm to 90 nm, 10 nm to 80 nm, 10 nm to 70 nm, 10 nm to 60 nm, 10 nm to 50 nm, 10 nm to 40 nm, 10 nm to 30 nm, 10 nm to 25 nm, 10 nm to 20 nm, 10 nm to 15 nm, or any and all and partial ranges in between. In some embodiments, the thickness is measured by observing the cross-section of the cut particles using a scanning electron microscope (SEM). In some embodiments, the thickness is measured using a transmission electron microscope (TEM).

[0022] In one embodiment, the CAM particles constitute 65% or more of the mass percentage in the composite layer.

[0023] In one embodiment, the carbon fibers coated with the oxide material have a mass percentage between 0.01% and 5.0% by mass in the composite layer.

[0024] In one embodiment, the carbon fibers coated with the oxide material have a mass percentage between 1.0 mass% and 3.0 mass% in the composite layer.

[0025] In one embodiment, the oxide material is an inorganic oxide material having a wide window of voltage stability.

[0026] In one embodiment, the inorganic oxide material is B2O3, Li3B 11 O 18 , Li3BO3, Li4B2O5, Li6B4O9, LiBO2, Li2B4O7, Li3B7O 12 , LiB3O5, LiNbO3, Li4SiO4, Li3PO4, Li2SiO3, LiPO3, Li2SO4, Li2WO4, Li2MoO4, Li2ZrO3, LiAlO2, Li2TiO3, Li4Ti5O 12 or selected from the group consisting of composite oxides thereof.

[0027] In one embodiment, the inorganic oxide material is stable over a voltage range of 1.9V to 5.0V.

[0028] In some embodiments, the inorganic oxide material is Li3BO3-doped Li2CO3 (LCBO), where the ratio of Li2CO3 to Li3BO3 is Li 2+x C 1-x B xIt is represented as O3. In some embodiments, 0 <x<1、0<x≦0.90、0<x≦0.80、0<x≦0.70、0<x≦0.60、0<x≦0.50、0<x≦0.45、0<x≦0.40、0<x≦0.35、0<x≦0.30、0<x≦0.25、0<x≦0.20、0<x≦0.15、0<x≦0.10、0.10≦x<1、0.10≦x≦0.90、0.10≦x≦0.80、0.10≦x≦0.70、0.10≦x≦0.60、0.10≦x≦0.50、0.10≦x≦0.45、0.10≦x≦0.40、0.10≦x≦0.35、0.10≦x≦0.30、0.10≦x≦0.25、0.10≦x≦0.20、0.15≦x<1、0.15≦x≦0.90、0.15≦x≦0.80、0.15≦x≦0.70、0.15≦x≦0.60、0.15≦x≦0.50、0.15≦x≦0.45、0.15≦x≦0.40、0.15≦x≦0.35、0.15≦x≦0.30、0.15≦x≦0.25、0.20≦x<1、0.20≦x≦0.90、0.20≦x≦0.80、0.20≦x≦0.70、0.20≦x≦0.60、0.20≦x≦0.50、0.20≦x≦0.45、0.20≦x≦0.40、0.20≦x≦0.35、0.20≦x≦0.30、0.25≦x<1、0.25≦x≦0.90、0.25≦x≦0.80、0.25≦x≦0.70、0.25≦x≦0.60、0.25≦x≦0.50、0.25≦x≦0.45、0.25≦x≦0.40、0.25≦x≦0.35、0.30≦x<1、0.30≦x≦0.90、0.30≦x≦0.80、0.30≦x≦0.70、0.30≦x≦0.60、0.30≦x≦0.50、0.30≦x≦0.45、0.30≦x≦0.40、0.35≦x<1、0.35≦x≦0.90、0.35≦x≦0.80、0.35≦x≦0.70、0.35≦x≦0.60、0.35≦x≦0.50、0.35≦x≦0.45、0.40≦x<1、0.40≦x≦0.90、0.40≦x≦0.80、0.40≦x≦0.70、0.40≦x≦0.60、0.40≦x≦0.50、0.45≦x<1、0.45≦x≦0.90、0.45≦x≦0.80、0.45≦x≦0.70、0.45≦x≦0.60、0.50≦x<1、0.50≦x≦0.90、0.50≦x≦0.80、0.50≦x≦0.70、0.50≦x≦0.60、0.70 ≤ x < 1, 0.70 ≤ x ≤ 0.90, 0.70 ≤ x ≤ 0.80, and all and partial ranges between them.

[0029] In one embodiment, the solid electrolyte is a sulfur-containing inorganic electrolyte.

[0030] In one embodiment, the solid electrolyte is Li2S-P2S5, Li2S-P2S5-LiHa, Li2S-P2S5-P2O5, Li2S-Li3PO4-P2S5, Li3PS4, Li4P2S6, Li 10 GeP2S 12 Li 3.25 Ge 0.25 P 0.75 S4, Li7P3S 11 Li 3.25 P 0.95 S4, and Li 7-x PS 6-x Ha x Selected from the group consisting of, where "Ha" is one or more halogen elements, and 0.2 <x<1.8である。

[0031] In one embodiment, the solid electrolyte has a mass percentage between 1% and 35% by mass in the composite layer. In some embodiments, the solid electrolyte may have concentrations in the range of 1% to 35% by mass, 1% to 30% by mass, 1% to 25% by mass, 1% to 20% by mass, 1% to 15% by mass, 1% to 10% by mass, 5% to 35% by mass, 5% to 30% by mass, 5% to 25% by mass, 5% to 20% by mass, 5% to 15% by mass, 10% to 35% by mass, 10% to 30% by mass, 10% to 25% by mass, 10% to 20% by mass, 15% to 35% by mass, 15% to 30% by mass, 15% to 25% by mass, 20% to 30% by mass, or any, all, and partial ranges between these.

[0032] In one embodiment, CAM is Li x Mn 1-y M y A2, Li x Mn1-y M y O 2-z X z 、 Li x Mn2O 4-z X z 、 Li x Mn 2-y M y A4、 Li x Co 1-y M y A2、 Li x Co 1-y M y O 2-z X z 、 Li x Ni 1-y M y A2、 Li x Ni 1-y M y O 2-z X z 、 Li x Ni 1-y Co y O 2-z X z 、 Li x Ni 1-y-z Co y M z A a 、 Li x Ni 1-y-z Co y M z O 2-a X a 、 Li x Ni 1-y-z Mn y M z A a 、 Li x Ni 1-y-z Mn y M z O 2-a X a selected from the group consisting of, wherein 0.95 ≦ x ≦ 1.1, 0 ≦ y ≦ 0.5, 0 ≦ z ≦ 0.5, 0 ≦ a ≦ 2, M is selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, and rare earth elements, A is selected from the group consisting of O, F, S, and P, and X is selected from the group consisting of F, S, and P.

[0033] In some embodiments, CAM is Lix MO2, Li x Ni 1-y-z Co y M1 z O2 and Li x Ni 1-y-z Mn y M2 z At least one selected from the group consisting of O2, where M is at least one selected from the group consisting of Ni, Co, Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements, and M1 is Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, M2 is at least one selected from the group consisting of Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements, and M2 is at least one selected from the group consisting of Co, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements, with 0.95≦x≦1.1, 1-yz>0, 0 <y≦0.5、0≦z≦0.5である。

[0034] In some embodiments, CAM is Li x MO2, Li x Ni 1-y-z Co y M1 z O2 and Li x Ni 1-y-z Mn y M2 zAt least one selected from the group consisting of O2, where M is at least one selected from the group consisting of Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements, and M1 is Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W , is at least one selected from the group consisting of Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements, and M2 is at least one selected from the group consisting of Co, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements, and 0.95≦x≦1.1, 1-yz>0, 0 <y≦0.5、0≦z≦0.5である。

[0035] In some embodiments, CAM is surface-doped with a doping element selected from the group consisting of Ni, Co, Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, Si, Ge, S, P, and rare earth elements.

[0036] In some embodiments, the CAM is in the form of particles having an average diameter in the ranges of approximately 1 μm to approximately 15 μm, approximately 1 μm to approximately 12 μm, approximately 1 μm to approximately 10 μm, approximately 1 μm to approximately 7 μm, approximately 1 μm to approximately 6 μm, approximately 3 μm to approximately 15 μm, approximately 3 μm to approximately 12 μm, approximately 3 μm to approximately 10 μm, approximately 3 μm to approximately 7 μm, approximately 3 μm to approximately 6 μm, approximately 5 μm to approximately 15 μm, approximately 5 μm to approximately 12 μm, approximately 5 μm to approximately 10 μm, and all and partial ranges in between. In some embodiments, the coated CAM is approximately 50% to approximately 99% by mass, approximately 50% to approximately 95% by mass, approximately 50% to approximately 90% by mass, approximately 50% to approximately 85% by mass, approximately 50% to approximately 80% by mass, approximately 55% to approximately 99% by mass, approximately 55% to approximately 95% by mass, approximately 55% to approximately 90% by mass, approximately 55% to approximately 85% by mass, approximately 55% to approximately 80% by mass, approximately 60% to approximately 99% by mass, approximately 60% to approximately 95% by mass, approximately 60% to approximately 90% by mass, and approximately 60% The concentrations in the cathode layer may be in the range of mass% to about 85 mass%, about 60 mass% to about 80 mass%, about 65 mass% to about 99 mass%, about 65 mass% to about 95 mass%, about 65 mass% to about 90 mass%, about 65 mass% to about 85 mass%, about 65 mass% to about 80 mass%, about 70 mass% to about 99 mass%, about 70 mass% to about 95 mass%, about 70 mass% to about 90 mass%, about 70 mass% to about 85 mass%, about 70 mass% to about 80 mass%, and all and partial ranges in between. In some embodiments, the CAM particles may be polycrystalline or monocrystalline. In some embodiments, the CAM particles may have a single particle size distribution or a multi-particle size distribution.

[0037] In some embodiments, CAM contains element Ni in a mole fraction of at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, or at least 85% of all metal elements other than lithium.

[0038] In one embodiment, the particles have an average diameter of 1 to 15 μm.

[0039] In one embodiment, the present disclosure relates to an all-solid-state battery (ASSB), a) The composite layer as the positive electrode, and b) The solid electrolyte layer between the positive and negative electrodes, We provide an all-solid-state battery equipped with the following features.

[0040] In one embodiment, the solid electrolyte layer is manufactured from a second solid electrolyte, which is the same as or different from the solid electrolyte in the positive electrode composite layer.

[0041] In one embodiment, the composite layer contains at least 65% by mass of CAM particles.

[0042] In one embodiment, the ASSB has an initial discharge ratio capacity of at least 180 mAh / g at a discharge rate of 0.5C.

[0043] In one embodiment, the ASSB has an initial discharge ratio capacity of at least 200 mAh / g at a discharge rate of 0.1C.

[0044] In one embodiment, the ASSB has a specific capacity of at least 180 mAh / g and a capacity retention rate of at least 95% after 20 cycles at a discharge rate of 0.5C.

[0045] This disclosure will be better understood by referring to the details of the experiments described below, but it will be readily apparent to those skilled in the art that the specific experiments described are for illustrative purposes only and are not intended to limit this disclosure as defined by the claims that follow.

[0046] Note that the transitional phrase "comprising," which is synonymous with "including," "containing," or "characterized by," is comprehensive or unrestricted and does not exclude any additional unlisted elements or methods. [Examples]

[0047] Example 1 Carbon fibers coated with an oxide material were prepared using the conventional sol-gel method. Li3B 11 O 18 For the coating, stoichiometric amounts of Li precursor (lithium acetate or lithium metal, etc.) and B precursor (triisopropyl borate, etc.) were dissolved in a dry solvent (ethanol, etc.) to form a coating solution containing the lithium precursor and boron precursor. A predetermined amount of CF (VGCF-H, fiber diameter 150 nm, fiber length 10-20 μm, 13 m) was used. 2 BET surface area per gram, aspect ratio of 10 to 500, true density 2.0 g / cm³ 3 Apparent density VGCF(registered trademark) (standard type) 0.04 g / cm³ 3 Single fiber resistivity 1 × 10 -4 A coating solution was added to the Ωcm. The predetermined amount of CF was used to determine the CF BET surface area and bulk density (Li3B) of the coating phase. 11 O 18 Regarding 2.16 g / cm³ 3 The desired coating thickness is calculated based on the following. The mixture is stirred for 30 minutes, then the solvent is removed under vacuum while sonicating to produce a gel of CF coated with Li and B precursors. The CF gel is then annealed at 300°C for 1 hour under an oxygen stream to produce Li3B 11 O 18 A layer of coated carbon fiber is formed. The specific discharge capacity and cycle life retention of various cathode layers with coated and uncoated CF are summarized in Table 1. The cathode layer consists of 65 mass% CAM (NCA88), 5 mass% CF (coated or uncoated), and 30 mass% LPS. The cathode layer is electrochemically evaluated in a torque cell using Li metal on copper as the anode and LPS as the SE. At 45°C, the cell was cycled from 2.8V to 4.25V with 0.1C charge / discharge for cycles 1 and 2, 0.33C charge / discharge for cycles 3 and 4, 1.0C charge / discharge for cycle 5, and 0.5C charge / discharge for cycles 6-25.

[0048] To electrically connect all CAM particles in the positive electrode layer and achieve a high initial discharge capacity, carbon fibers or other electronically conductive materials are required. However, the decomposition of SE in contact with CF results in considerable degradation. In this disclosure, an oxide material (e.g., LBO(Li3B)) with a thickness of 2 to 50 nm is used on the CF. 11 O 18 This was addressed by the following method. The coating thickness is calculated stoichiometrically using the BET surface area of ​​the CF, the bulk density of the coating composition, and the mass / molar amount of reagent in the coating solution (assuming 100% reagent utilization). The coating thickness is confirmed by TEM analysis. A typical TEM image is shown in Figure 2.

[0049] The coated CF reduced the degradation of discharge capacity while maintaining a high level of initial battery performance. For example, for a half-cell containing uncoated CF, the initial discharge capacity was 205.33 mAh / g at a discharge rate of 0.1C. With 2, 20, and 50 nm coatings of LBO on VGCF, the initial discharge capacities were 203.91 mAh / g, 206.76 mAh / g, and 219.23 mAh / g, respectively. When the LBO thickness was 100 nm, the initial discharge capacity decreased to 178.73 mAh / g. The coated CF effectively reduced cell degradation, as is evident from the retention of cycle life capacity after 20 cycles at 0.5C in Table 1 and Figure 3, and the theoretical capacity of CAM (NCA88--LiNi 0.88 Co 0.09 Al 0.03 Regarding O2, as is evident from the increase in initial discharge capacity at a discharge rate of 0.1C, approaching 219.8mAh / g, it will be extremely important for achieving high-capacity SSB.

[0050] [Table 1] VGCF coatings are not limited to Li-containing oxides or lithium borate. Figure 4 shows 20nm B2O3 and 20nm Li3B 11 O 18The cycle performance of uncoated VGCF, along with 20nm Li3BO3 and 10nm LiNbO3, is shown. The cathode layer consists of 65 mass% CAM (NCA88), 5 mass% CF (coated or uncoated), and 30 mass% LPS. The cathode layer is electrochemically evaluated in a torque cell using Li metal on copper as the anode and LPS as the SE. The cell was cycled from 2.8V to 4.25V at 0.1C charge / discharge for cycles 1 and 2, 0.33C charge / discharge for cycles 3 and 4, 1.0C charge / discharge for cycle 5, and 0.5C charge / discharge for cycles 6-25. All coating compositions except Li3BO3 showed improved discharge capacity and capacity retention up to the 25th cycle compared to uncoated VGCF.

[0051] [Table 2] Hereinafter, preferred embodiments of the present invention will be described item by item.

[0052] Embodiment 1 Particles of a cathode active material (CAM), a solid electrolyte, and carbon fibers coated with an oxide material, forming a composite layer.

[0053] Embodiment 2 The composite layer according to Embodiment 1, wherein the oxide material coated on the carbon fibers has a thickness of 1 to 70 nm.

[0054] Embodiment 3 The composite layer according to Embodiment 1, wherein the oxide material coated on the carbon fibers has a thickness of 2 to 50 nm.

[0055] Embodiment 4 The composite layer according to Embodiment 1, wherein the particles of CAM have a mass percentage of 65% or more in the composite layer.

[0056] Embodiment 5 The composite layer according to Embodiment 1, wherein the carbon fibers coated with the oxide material have a mass percentage between 0.01% and 5.0% in the composite layer.

[0057] Embodiment 6 The composite layer according to Embodiment 1, wherein the carbon fibers coated with the oxide material have a mass percentage between 1.0% and 3.0% in the composite layer.

[0058] Embodiment 7 The composite layer according to Embodiment 1, wherein the oxide material is an inorganic oxide material.

[0059] Embodiment 8 The inorganic oxide material is B 2 O 3 , Li 3 B 11 O 18 , Li 4 B 2 O 5 , Li 6 B 4 O 9 , LiBO 2 , Li 2 B 4 O 7 , Li 3 B 7 O 12 , LiB 3 O 5 , LiNbO 3 , Li 4 SiO 4 , Li 3 PO 4 , Li 2 SiO 3 , LiPO 3 , Li 2 SO 4 , Li 2 WO 4 , Li 2 MoO 4 , Li 2 ZrO 3 , LiAlO 2 , Li 2 TiO 3 , Li 4 Ti 5 O 12 , and is selected from the group consisting of its composite oxides. The composite layer according to Embodiment 7.

[0060] Embodiment 9 The composite layer according to Embodiment 7, wherein the inorganic oxide material is stable over a voltage range from 1.9 V to 5.0 V.

[0061] Embodiment 10 The composite layer according to Embodiment 1, wherein the solid electrolyte is a sulfur-containing inorganic electrolyte.

[0062] Embodiment 11 The solid electrolyte is selected from the group consisting of Li 2 S-P 2 S 5 , Li 2 S-P 2 S 5 -LiHa, Li 2 S-P 2 S 5 -P 2 O 5 , Li 2 S-Li 3 PO 4 -P 2 S 5 , Li 3 PS 4 , Li 4 P 2 S 6 , Li 10 GeP 2 S 12 , Li 3.25 Ge 0.25 P 0.75 S 4 , Li 7 P 3 S 11 , Li 3.25 P 0.95 S 4 , and Li 7-x PS 6-x [[ID=7th]], Ha x , where "Ha" is one or more halogen elements and 0.2 < x < 1.8. The composite layer according to Embodiment 1.

[0063] Embodiment 12 The composite layer according to Embodiment 1, wherein the solid electrolyte has a mass percentage between 1% and 35% in the composite layer.

[0064] Embodiment 13 The CAM is Li x MO 2 , Li x Ni 1-y-z Co y M1 z O 2 and Li xNi 1-y-z Mn y M2 z O 2 At least one selected from the group consisting of, wherein M is at least one selected from the group consisting of Ni, Co, Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements; M1 is at least one selected from the group consisting of Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements; M2 is at least one selected from the group consisting of Co, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements; 0.95 ≦ x ≦ 1.1, 1 - y - z > 0, 0 < y ≦ 0.5, 0 ≦ z ≦ 0.5, the composite layer according to Embodiment 1.

[0065] Embodiment 14 The composite layer according to Embodiment 1, wherein the particles have an average diameter of 1 to 15 μm.

[0066] Embodiment 15 An all-solid-state battery (ASSB) comprising: a) the composite layer according to Embodiment 1 as a positive electrode; b) a negative electrode layer, and c) a solid electrolyte layer between the positive electrode and the negative electrode. The ASSB provided with.

[0067] Embodiment 16 The ASSB according to Embodiment 15, wherein the solid electrolyte layer is the same as or different from the solid electrolyte in the positive electrode composite layer.

[0068] Embodiment 17 The ASSB according to Embodiment 15, wherein the composite layer contains at least 65% by mass of CAM particles.

[0069] Embodiment 18 The ASSB according to Embodiment 17, wherein the ASSB has an initial discharge specific capacity of at least 180 mAh / g at a discharge rate of C / 2.

[0070] Embodiment 19 The ASSB according to Embodiment 17, wherein the ASSB has an initial discharge specific capacity of at least 200 mAh / g at a discharge rate of C / 10.

[0071] Embodiment 20 The ASSB according to Embodiment 17, wherein the ASSB is charged to 4.25V, discharged at 45°C at 0.1C for cycles 1 and 2, 0.33C for cycles 3 and 4, 1.0C for cycle 5, and 0.5C for cycles 6 through 20, for a total of 20 cycles, and the ASSB exhibits a specific capacity of at least 180mAh / g and a cycle life retention rate of at least 95% at the 20th cycle, the cycle life retention rate being the ratio of the discharge specific capacity at the 20th cycle to the initial discharge specific capacity at 45°C and 0.5C.

Claims

1. Particles of cathode active material (CAM), Solid electrolytes, and Carbon fibers coated with oxide material, A composite layer of positive electrodes including, The oxide material coated on the carbon fiber has a thickness of 1 to 70 nm. The aforementioned oxide material is an inorganic oxide material, A composite layer in which the inorganic oxide material is selected from the group consisting of B2O3 and Li3B11O18.

2. The composite layer according to claim 1, wherein the CAM particles constitute 65% or more of the mass percentage in the composite layer.

3. The composite layer according to claim 1, wherein the carbon fibers coated with the oxide material have a mass percentage between 0.01% by mass and 5.0% by mass in the composite layer.

4. The composite layer according to claim 1, wherein the inorganic oxide material is stable over a voltage range of 1.9V to 5.0V.

5. The composite layer according to claim 1, wherein the solid electrolyte is a sulfur-containing inorganic electrolyte.

6. where the solid electrolyte is Li ４ , ５ , ４ , ６－ｘ , ０．２５ , ４ , １２ , ３．２５ , １０ , ３ , ２ , ７ , ４ , ０．７５ , ３ , ３．２５ , ｘ , ２ , ７－ｘ , ６ , ０．９５ , １１ S - P ２ S ５ 、Li ２ S - P ２ S ５ - LiHa、Li ２ S - P ２ S ５ - P ２ O ５ 、Li ２ S - Li ３ PO ４ - P ２ S ５ 、Li ３ PS ４ 、Li ４ P ２ S ６ 、Li １０ GeP ２ S １２ 、Li ３．２５ Ge ０．２５ P ０．７５ S ４ 、Li ７ P ３ S １１ 、Li ３．２５ P ０．９５ S ４ 、and Li ７－ｘ PS ６－ｘ Ha ｘ selected from the group consisting of, where "Ha" is one or more halogen elements and 0.2 < x < 1.8, the composite layer according to claim 1.

7. The composite layer according to claim 1, wherein the solid electrolyte has a mass percentage between 1% by mass and 35% by mass in the composite layer.

8. The aforementioned CAM is Li ｘ MO ２ Li ｘ Ni １－ｙ－ｚ Co ｙ M1 ｚ O ２ and Li ｘ Ni １－ｙ－ｚ Mn ｙ M2 ｚ O ２ At least one selected from the group consisting of, where M is at least one selected from the group consisting of Ni, Co, Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements, and M1 is Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn The composite layer according to claim 1, wherein M2 is at least one selected from the group consisting of Cd, Ga, In, Sn, and rare earth elements, and M2 is at least one selected from the group consisting of Co, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements, and 0.95 ≤ x ≤ 1.1, 1 - y - z > 0, 0 < y ≤ 0.5, and 0 ≤ z ≤ 0.

5.

9. All-solid-state batteries (ASSBs) a) The composite layer according to claim 1 as the positive electrode, b) Negative electrode layer, and c) A solid electrolyte layer between the positive electrode and the negative electrode, ASSB equipped with this.

10. The ASSB according to claim 9, wherein the solid electrolyte layer is the same as or different from the solid electrolyte in the positive electrode composite layer.

11. The ASSB according to claim 9, wherein the ASSB has an initial discharge ratio capacity of at least 180 mAh / g at a discharge rate of 0.5 C.

12. The ASSB according to claim 9, wherein the ASSB is charged to 4.25V, discharged at 45°C at 0.1C for cycles 1 and 2, 0.33C for cycles 3 and 4, 1.0C for cycle 5, and 0.5C for cycles 6 through 20, for a total of 20 cycles, and the ASSB exhibits a specific capacity of at least 180mAh / g and a cycle life retention rate of at least 95% at the 20th cycle, the cycle life retention rate being the ratio of the discharge specific capacity at the 20th cycle to the initial discharge specific capacity at 45°C and 0.5C.

Images