Lithium battery

Abstract

The present invention provides a solid-state battery, preferably a pouch cell, comprising: (i) a cathode including a cathode active material containing Li ions, graphene, and optionally a binder; (ii) an electrolyte; and (iii) an anode, preferably a lithium anode, wherein the electrolyte is disposed between the cathode and the anode.

Description

Technical Field

[0001] The present invention relates to a solid battery comprising a cathode comprising graphene, a cathode active material and optionally a binder, in particular a pouch cell. The present invention also relates to a method for manufacturing a solid battery, and to the use of a solid battery in devices such as electric vehicles and portable electronic devices. Furthermore, the present invention relates to a solid cathode composition comprising a cathode active material containing Li ions, activated graphene, and optionally a binder, and to a method for manufacturing such a composition, a cathode comprising such a composition, and the use of such a composition for manufacturing a solid cathode and / or a solid battery, such as a pouch cell.

Background Art

[0002] There is a rapid transition to battery-powered vehicles for which lithium-ion batteries are the most promising technology. Conventional lithium-ion batteries have several inherent drawbacks including capacity fade during cycle life (i.e., long-term performance degradation) and safety risks. In particular, the liquid electrolytes used in such batteries can cause thermal runaway, electrolyte leakage and combustion.

[0003] These problems have led to the development of batteries with solid electrolytes. One of the main problems with solid lithium metal batteries is capacity fade over time, i.e., the battery capacity decreases during charge / discharge cycles and the battery life is shortened. In solid batteries, the solid electrolyte / electrode interface plays an important role in determining the cycle life. Therefore, current research focuses on ways to improve the interfacial resistance (e.g., discharge plasma sintering, pressure activation of pouch cells) to enable the cell to operate for longer periods at higher capacities. Such methods strive to ensure that appropriate solid electrolyte / electrode contact is achieved during the battery manufacturing process. However, these methods are costly and time-consuming.

[0004] At the same time, for example, it is highly desirable to provide a lighter battery suitable for use in electric vehicles. For this reason, research is being actively conducted in the field of pouch cells that achieve higher packing efficiency and weight reduction than any conventional type of battery. Pouch cells also offer the advantage of providing flexibility in size and shape and can be easily provided, for example, in dimensions suitable for applications with a larger surface area, such as portable electronic devices. However, an increase in the size of the pouch cell amplifies the cost and time of the complex manufacturing process. SUMMARY OF THE INVENTION

[0005] Viewed from a first aspect, the present invention provides a solid-state battery comprising: (i) a cathode comprising a cathode active material containing Li ions, graphene, and optionally a binder; (ii) an electrolyte; (iii) an anode, preferably a lithium anode, wherein the electrolyte is disposed between the cathode and the anode. Preferably, the solid-state battery is in the form of a pouch cell.

[0006] Viewed from a further aspect, the present invention provides a method for manufacturing the above-described solid-state battery, comprising:

[0007] (i) preparing a cathode comprising a cathode active material containing Li ions, graphene, and optionally a binder; (ii) preparing an electrolyte; (iii) preparing an anode; (iv) laminating the cathode, electrolyte, and anode to form the solid-state battery. (v) Viewed from a further aspect, the present invention provides a method for manufacturing a battery pack, comprising:

[0008] (i) manufacturing the battery as defined above; (ii) enclosing the battery in a package defining a port; (iii) Provided is a method for manufacturing a pouch cell according to any of the above claims, including

[0009] Viewed from a further aspect, the present invention provides for the use of the above-described solid-state battery, preferably a pouch cell, in an electronic device, such as an electric vehicle or a portable electronic device.

[0010] Viewed from a further aspect, the present invention provides a device, such as an electric vehicle, comprising the above-described solid-state battery, preferably a pouch cell.

[0011] Viewed from a further aspect, the present invention (i) a cathode comprising a cathode active material containing Li ions, (ii) activated graphene, and (iii) optionally a binder, and provides a solid cathode composition.

[0012] Viewed from a further aspect, the present invention provides a method for manufacturing the above-described solid composition, comprising mixing a cathode active material containing Li ions, activated graphene, and optionally a binder.

[0013] Viewed from a further aspect, the present invention provides a solid cathode comprising the composition defined above.

[0014] Viewed from a further aspect, the present invention provides a method for manufacturing the solid cathode defined above, comprising depositing a slurry of the solid cathode composition on a cathode current collector and drying to form the cathode.

[0015] Viewed from a further aspect, the present invention provides for the use of the composition defined above for manufacturing a solid cathode or a solid-state battery.

[0016] Definition As used herein, the term "solid-state battery" refers to a battery that includes a solid electrode and a solid electrolyte. The presence of a solid electrolyte is what differentiates it from conventional batteries that tend to have liquid or polymer gel electrolytes.

[0017] As used herein, the term "secondary battery" means a battery that can be recharged by passing an electric current through it, i.e., it can be reused. The term "secondary battery" may be used interchangeably with "storage battery".

[0018] As used herein, the term "pouch cell" refers to a battery housed in a non-rigid pouch, e.g., a non-rigid metal foil pouch.

DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention relates to (i) a cathode comprising a cathode active material containing Li ions, graphene, and optionally a binder, (ii) an electrolyte, (iii) an anode, preferably a lithium anode, and is a solid-state battery comprising wherein the electrolyte is disposed between the cathode and the anode, and relates to a solid-state battery.

[0020] Preferably, the solid-state battery is a secondary battery.

[0021] Preferably, the solid-state battery is in the form of a pouch cell.

[0022] Even more preferably, the solid-state battery is a secondary battery in the form of a pouch cell.

[0023] The solid-state battery of the present invention advantageously achieves high-capacity cycle stability over a long period (e.g., more than 100 cycles). Therefore, the solid-state battery of the present invention retains at least 60% of its original capacity after about 150 cycles, and in some cases, at least 80% of its original capacity after about 150 cycles. In contrast, conventional solid-state batteries maintain only 30% of their capacity after about 40 cycles.

[0024] The solid-state battery of the present invention comprises a cathode comprising a cathode active material containing Li ions, optionally a binder, and graphene. The graphene may be powdered graphene or activated graphene. The presence of graphene in the cathode of the solid-state battery of the present invention significantly improves its high-capacity cycle stability, which means that the battery can be reused many more times than conventional secondary solid-state batteries.

[0025] Advantageously, the graphene can be added to a conventional cathode active material containing Li ions and optionally a binder to prepare the cathode of the solid-state battery. This facilitates the preparation of pouch cells, including relatively large-sized pouch cells, by the solid-state battery of the present invention. This is beneficial because it avoids the need for costly and time-consuming processes such as discharge plasma sintering and pressure activation, which are generally required during pouch cell manufacturing.

[0026] Cathode The cathode present in the solid-state battery of the present invention preferably includes a cathode current collector. Any material conventionally used for this purpose can be used. For example, the cathode current collector may be a sheet, foil, foam, or mesh containing a conductive metal, such as aluminum (Al), copper (Cu), titanium (Ti), germanium (Ge), stainless steel, or a mixture thereof. Optionally, the cathode current collector may preferably include a carbon coating over its entire surface. When a cathode current collector is present, the cathode active material containing Li ions, graphene, and optionally a binder are preferably present as a layer on the cathode current collector. Optionally, the cathode does not include a cathode current collector.

[0027] The cathode present in the solid battery of the present invention contains a cathode active material containing Li ions, graphene, and optionally a binder. Preferably, the cathode contains a binder.

[0028] The cathode active material containing Li ions may be any cathode active material capable of intercalating and deintercalating lithium ions. A considerable number of such materials are known in the art and are commercially available. Preferred cathode active materials include lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, lithium manganese oxide, lithium copper oxide, lithium vanadium oxide, lithium nickel composite oxide, lithium nickel cobalt aluminum oxide, lithium nickel manganese oxide, lithium manganese composite oxide, and Ni-Co-Mn ternary lithium metal oxide. Any known stoichiometry can be used.

[0029] Representative examples of suitable cathode active materials include lithium cobalt oxide (LiCoO2, LCO), lithium nickel oxide (LiNiO2, LiNi2O4), lithium iron phosphate (LiFePO4), lithium manganese oxide (Li 1+x Mn 2-x O4 (where x is from 0 to 0.33), for example, LiMnO3, LiMn2O3), lithium copper oxide (Li2CuO2), lithium vanadium oxide (LiV3O8), lithium nickel composite oxide (LiNi 1-x M x O2 (where M is Co, Al, Cu, Fe, Mg, B, or Ge, and x is from 0.01 to 0.3)), lithium nickel manganese oxide (LiNi 1-x Mn x O4 (where x > 0.5), for example, LiNi 0.5 Mn 1.5 O4), lithium nickel cobalt aluminum oxide (LiNi x Co y Al zO₂ (where 0 < x < 1, 0 < y < 1, and 0 < z < 1), NCA), lithium manganese composite oxide (LiMn 2-x M x O₂ (where M is Co, Ni, Fe, Cr, Zn, or Ta, and x is 0.01 - 0.1), or LiMn₃MO₈ (where M is Fe, Co, Ni, Cu, or Zn)), LiMn₂O₄ (LMO), nickel - cobalt - manganese ternary lithium metal oxide (Li[Ni x Co 1-2x Mn x O₂ (where x is greater than 0 and less than 0.5), NMC), and mixtures thereof.

[0030] Preferably, the cathode active material containing Li ions is lithium cobalt oxide (LiCoO₂, LCO), LiMn₂O₄ (LMO), lithium nickel cobalt aluminum oxide (LiNi x Co y Al z O₂ (where 0 < x < 1, 0 < y < 1, and 0 < z < 1), NCA), lithium iron phosphate (LiFePO₄), and nickel - cobalt - manganese ternary lithium metal oxide (Li[Ni x Co 1-2x Mn x O₂ (where x is greater than 0 and less than 0.5), NMC). Even more preferably, the cathode active material containing Li ions is lithium nickel cobalt aluminum oxide (LiNi x Co y Al z O₂ (where 0 < x < 1, 0 < y < 1, and 0 < z < 1), NCA, for example, LiNi 0.80 Co 0.15 Al 0.05 O₂ (NCA8155)), and nickel - cobalt - manganese ternary lithium metal oxide (Li[Ni x Co 1-2x Mn x O₂ (where x is greater than 0 and less than 0.5), NMC). Even more preferably, the cathode active material containing Li ions is of the formula Li[Ni x Co 1-2x Mn xO₂ (where x is greater than 0 and less than 0.5) is a Ni-Co-Mn ternary lithium metal oxide (NMC). Examples include LiNi 0.33 Co 0.33 Mn 0.33 O₂ (NCM333), LiNi 0.50 Co 0.20 Mn 0.30 O₂ (NCM523), LiNi 0.60 Co 0.20 Mn 0.2 O₂ (NCM622), and LiNi 0.80 Co 0.10 Mn 0.10 O₂ (NCM811). A particularly preferred cathode active material containing Li ions is Li[Ni 0.6 Co 0.2 Mn 0.2 O]₂ (NMC622).

[0031] The cathode active material can be in any form. The cathode active material is preferably in the form of particles, and more preferably in the form of spherical particles. The average particle diameter of the cathode active material is preferably 1 nm to 100 microns, preferably 10 nm to 75 microns, more preferably 150 nm to 50 microns. For example, the average particle diameter of the cathode active material can be less than 500 nm, for example, 50 nm to 450 nm or 5 microns to 50 microns, for example, 5 microns to 20 microns. However, the advantages of the present invention are most prominent when the cathode active material has a relatively large average particle diameter such as 5 microns to 50 microns.

[0032] The cathode present in the solid battery of the present invention preferably contains 50% to 99% by weight, more preferably 65% to 90% by weight, and even more preferably 70% to 90% by weight of the cathode active material based on the total weight of the cathode.

[0033] The cathode present in the solid battery of the present invention contains graphene. Preferably, the graphene is in the form of platelets, more preferably nanoplatelets. Preferably, the platelets have an average particle size of 1 micron to 5 microns. As-supplied graphene tends to contain aggregates, which can be decomposed during processing, for example, by shearing.

[0034] In a preferred cathode of the solid battery of the present invention, the graphene is activated graphene. The activation process preferably improves the flaky form of the graphene and / or reduces the thickness of the graphene plates or flakes. Preferably, the average particle size of the activated graphene is 0.1 micron to 2 microns, more preferably 0.1 micron to 1 micron. Preferably, the average thickness of the activated graphene is 1 nm to 9 nm, more preferably 2 nm to 4 nm. Preferably, the activation process results in thinner flakes with reduced aggregation.

[0035] Preferably, the activated graphene has a specific surface area of 2 300 m 2 / g to 3000 m 2 / g, more preferably 500 m 2 / g to 800 m 2 / g, even more preferably 550 m 2 / g to 700 m

[0036] Preferably, the activation process increases the porosity of the graphene.

[0037] Preferably, the activated graphene is (a) obtained by contacting graphene with an alkaline solution to obtain alkali-treated graphene, and (b) heating the alkali-treated graphene in an inert atmosphere to obtain activated graphene. It is prepared by the following steps.

[0038] Suitable alkaline solutions include KOH, NaOH, KHCO3, K2C2O4, melamine, and mixtures thereof. Preferably, the alkaline solution is an aqueous hydroxide solution, and even more preferably KOH.

[0039] Preferably, the heating is carried out at a temperature of 600°C to 1200°C, more preferably 700°C to 1000°C, and even more preferably 800°C to 950°C. Preferably, the heating is carried out for 0.25 hours to 5 hours, more preferably 0.5 hours to 2.5 hours, and even more preferably 0.75 hours to 2 hours. Preferably, the heating is carried out at ambient pressure. Preferably, the heating is carried out in an argon atmosphere.

[0040] In a preferred preparation process of activated graphene, the alkali-treated graphene is dried (e.g., at 50°C to 100°C in a furnace) and pulverized before the heating in step (b). The pulverization can be carried out, for example, using a mortar and pestle.

[0041] In yet another preferred process, the activated graphene obtained in step (b) is washed with water, preferably deionized water, and dried (e.g., at 50°C to 100°C in a furnace). Optionally, the washed activated graphene is then heated. Preferably, the heating is carried out at a temperature of 600°C to 1200°C, more preferably 700°C to 1000°C, and even more preferably 800°C to 950°C. Preferably, the heating is carried out for 0.25 hours to 5 hours, more preferably 0.5 hours to 2.5 hours, and even more preferably 0.75 hours to 2 hours. Preferably, the heating is carried out at ambient pressure. Preferably, the heating is carried out in an argon atmosphere.

[0042] Therefore, a particularly preferred preparation process of activated graphene is (a) contacting graphene with an alkaline solution to obtain alkali-treated graphene; (b) drying and pulverizing the alkali-treated graphene to obtain pulverized alkali-treated graphene; (c) Heating the pulverized and alkali-treated graphene in an inert atmosphere to obtain activated graphene; (d) Washing the activated graphene with water and drying it; (e) Optionally, heating the activated graphene in an inert atmosphere; It includes.

[0043] Treatment with an alkaline solution followed by heating is thought to increase the porosity of graphene and improve its flaky morphology, for example, by reducing the thickness of the flakes.

[0044] As described above, the presence of graphene in the cathode of the solid battery of the present invention is considered to improve capacity retention, that is, the battery can achieve or substantially achieve its original capacity for a greater number of cycles. Without being bound by theory, graphene is thought to encapsulate cathode active particles containing Li ions and allow a certain degree of flexibility during the expansion / contraction that occurs during the charge / discharge process. This gives good mechanical stability to the cathode and thus improves the cycle performance. The presence of graphene on the surface of the cathode active particles also increases the number of contact sites with both the electrolyte and other cathode active particles. This improves the electrical contact and makes it possible to facilitate the flow of electrons from the current collector to the active material for the Li intercalation reaction, improving the electrical interconnectivity of the active material and increasing the capacity. Also, by reducing the electrical resistance, it becomes possible to use a higher current density.

[0045] When activated graphene is present in the cathode, the capacity retention is most significantly improved. Again, without being bound by theory, this is thought to be due to an improved form of graphene (i.e., a more platelet-like form) that enables graphene to more effectively wrap around and conform to the cathode active particles, particularly while increasing the number of contact sites with the electrolyte. As the porosity of the activated graphene increases, it is thought to be able to provide more and / or larger pathways for Li ions to move through the cathode, while still providing a conductive network for in-plane electrical conductivity within the cathode. The mechanical stability of the cathode is also improved by the activated graphene, reducing the detrimental effects of any volume expansion and contraction that occur during the cell's charge cycles. This improves the charging performance of the battery.

[0046] The cathode present in the solid battery of the present invention preferably contains 0.5 wt% to 20 wt%, more preferably 5 wt% to 17.5 wt%, and even more preferably 5 wt% to 15 wt% of graphene, preferably activated graphene, based on the total weight of the cathode.

[0047] Optionally, the cathode present in the solid battery of the present invention contains other conductive agents. Examples of suitable conductive agents include carbon black, graphite, acetylene black, carbon fiber, carbon nanotubes, metal particles, and combinations thereof. When present, the other conductive agent is preferably present in the cathode in an amount of 0.5 wt% to 15 wt%, more preferably 2.5 wt% to 8 wt%, and even more preferably 4 wt% to 6 wt%, based on the total weight of the cathode. Preferably, the conductive agent contains carbon. Such a conductive agent may also be referred to as a carbonaceous additive.

[0048] Preferably, the cathode present in the solid battery of the present invention contains graphene nanoplatelets and one or more carbonaceous additives such as carbon black and carbon nanotubes. Advantageously, the combination of graphene nanoplatelets and the carbonaceous additive can provide a synergistic effect that improves the conductivity, performance, and stability of the solid battery.

[0049] Optionally, the cathode present in the solid battery of the present invention further contains an electrolyte material, preferably a trace amount of electrolyte material, as an additive (which may be plural). The electrolyte material may be a ceramic electrolyte material, for example, Li 1.4 Al 0.4 Ti 1.6 (PO4)3 (LATP).

[0050] Preferably, the cathode present in the solid battery of the present invention contains one or more carbonaceous additives such as graphene, preferably graphene nanoplatelets, carbon black, and carbon nanotubes, and Li 1.4 Al 0.4 Ti 1.6 (PO4)3 (LATP). The combination of graphene and LATP and / or carbonaceous additives can provide a synergistic effect to improve the stability of the solid battery.

[0051] The cathode present in the solid battery of the present invention preferably contains a binder. Any conventional binder can be used. Representative examples of suitable binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene (PE), styrene-butadiene rubber (SBR), polyethylene oxide (PEO), or combinations thereof. Preferably, the binder is polyvinylidene fluoride (PVDF). Optionally, the cathode does not contain a binder.

[0052] The cathode present in the solid battery of the present invention preferably contains a binder in an amount of 2.5% to 20% by weight, more preferably 5% to 17.5% by weight, and even more preferably 5% to 15% by weight, based on the total weight of the cathode.

[0053] Optionally, the cathode present in the solid battery of the present invention contains one or more additives. Typical additives that may be present include fillers, dispersants, stabilizers, ionic liquids (e.g., EMImTFSI), and salts (e.g., AlF3, LiF). When present, such additives are preferably present in the cathode in an amount of 1 wt% to 10 wt%, more preferably 2 wt% to 9 wt%, and even more preferably 4 wt% to 5 wt% based on the total weight of the cathode.

[0054] The cathode present in the solid battery of the present invention preferably has a total thickness of 40 microns to 1000 microns, more preferably 50 microns to 250 microns, and even more preferably 150 microns to 250 microns.

[0055] Electrolyte The solid electrolyte present in the solid battery of the present invention may be any conventional solid electrolyte. The solid electrolyte may be an ionic liquid, an inorganic solid electrolyte, a solid polymer electrolyte, or a composite electrolyte. Preferably, the solid electrolyte is a composite electrolyte. The composite electrolyte includes a polymer matrix and an inorganic filler therein, preferably an inorganic solid electrolyte.

[0056] Suitable inorganic solid electrolytes include solid sulfide electrolytes, solid oxide electrolytes, solid nitride electrolytes, and solid halide electrolytes. Solid sulfide electrolytes and solid oxide electrolytes are preferred. Representative examples of suitable solid sulfide electrolytes include LPS halogens (Cl, Br, and I), Li2S-P2S5, and Li 2- P2S 5- LiI. Representative examples of suitable solid oxide electrolytes include NASICON-type oxides, i.e., sodium superionic conductors (e.g., Li 1.5 Al 0.5 Ti 1.5 (PO4)3, Li 1.4 Al 0.4 Ti 1.6 (PO4)3), garnet-type oxides (e.g., Li7La3Zr2O 12 ) and perovskite-type oxides (e.g., LiLaTiO3).

[0057] Preferably, as the solid oxide electrolyte, Li 1.4 Al 0.4 Ti 1.6 (PO4)3 (LATP) may be mentioned.

[0058] Suitable solid polymer electrolytes include polyethylene oxide (PEO), polyethylene glycol, polypropylene oxide, polyphosphazene, polysiloxane (e.g., PDMS), polycarbonate, polyester, polynitrile (e.g., PAN), polyalcohol (PVA), polyamine (e.g., PEI), fluoropolymer (e.g., PVDF, PVDF-HFP), and copolymers thereof.

[0059] Suitable composite electrolytes include polymers selected from polyethylene oxide, polyethylene glycol, polypropylene oxide, polyphosphazene, polysiloxane (e.g., PDMS), polycarbonate, polyester, polynitrile (e.g., PAN), polyalcohol (PVA), polyamine (e.g., PEI), fluoropolymer (e.g., PVDF, PVDF-HFP), and copolymers thereof, and inorganic fillers. Preferably, the inorganic filler is an inorganic solid electrolyte. Particularly preferably, the inorganic filler is a solid sulfide electrolyte, a solid oxide electrolyte, a solid nitride electrolyte or a solid halide electrolyte, and even more preferably a solid sulfide electrolyte or a solid oxide electrolyte. Representative examples of suitable solid sulfide electrolytes include LPS halogen (Cl, Br, and I), Li2S-P2S5, and Li 2- P2S 5- LiI may be mentioned. Representative examples of suitable solid oxide electrolytes include NASICON-type oxides, that is, sodium superionic conductors (e.g., Li 1.5 Al 0.5 Ti 1.5 (PO4)3, Li 1.4 Al 0.4 Ti 1.6 (PO4)3), garnet-type oxides (e.g., Li7La3Zr2O 12) and perovskite oxides (e.g., LiLaTiO3). One particularly preferred composite electrolyte is PVDF and Li 1.4 Al 0.4 Ti 1.6 (PO4)3.

[0060] The preferred composite electrolyte present in the solid battery of the present invention preferably contains 5% to 30% by weight, more preferably 10% to 25% by weight of the polymer, based on the total weight of the electrolyte. Correspondingly, the preferred composite electrolyte present in the solid battery of the present invention preferably contains 70% to 95% by weight, more preferably 75% to 90% by weight of the inorganic solid electrolyte, based on the total weight of the electrolyte.

[0061] Preferably, the solid electrolyte is pre-impregnated with one or more lithium salts. This is a known process, and any lithium salt conventionally used for this purpose can be used. Suitable lithium salts include lithium perchlorate (LiClO4), lithium triflate (LiCF3SO3), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiPF6), lithium trifluoromethanesulfonylimide (LiN(CF3SO2)2), or mixtures thereof.

[0062] Optionally, the electrolyte present in the solid battery of the present invention contains one or more additives. Typical additives that may be present include dispersants, stabilizers, ionic liquids (e.g., EMImTFSI), and salts (e.g., AlF3, LiF). When present, such additives are preferably present in the electrolyte in an amount of 0% to 5% by weight, more preferably 0.5% to 3% by weight, even more preferably 1% to 1.5% by weight, based on the total weight of the electrolyte. However, preferably, the electrolyte does not contain any additives.

[0063] The electrolyte present in the solid battery of the present invention preferably has a total thickness of 10 microns to 500 microns, more preferably 25 microns to 250 microns, even more preferably 50 microns to 250 microns.

[0064] Anode The anode present in the solid battery of the present invention preferably includes an anode current collector. Any material conventionally used for this purpose can be used. For example, the anode current collector may be a sheet, foil, foam or mesh containing a conductive metal such as aluminum (Al), copper (Cu), titanium (Ti), germanium (Ge), stainless steel or a mixture thereof. Preferably, the anode current collector is aluminum. Preferably, lithium is electrodeposited on the anode current collector during cycling. Advantageously, this reduces the formation of dendrites and improves the stability of the battery, for example, as compared to the use of a lithium metal anode.

[0065] Preferably, the anode present in the solid battery of the present invention can include (e.g., consist only of) lithium metal (e.g., lithium foil).

[0066] The anode present in the solid battery of the present invention optionally includes an anode active material. When present, the anode active material preferably exists as a layer between the electrolyte and the anode current collector. Examples of suitable anode active materials include carbon materials such as natural graphite and spherical graphite, silicon materials such as amorphous silica, lithium titanium oxides such as Li4Ti5O 12 and metal lithium. Carbon materials are particularly preferred.

[0067] Optionally, the anode further includes a conductive agent. Examples of suitable conductive agents include carbon black, graphite, acetylene black, carbon fibers, carbon nanotubes, metal particles and combinations thereof.

[0068] Optionally, the anode contains a binder. Suitable examples include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene (PE), styrene butadiene rubber (SBR), or combinations thereof. Preferably, the binder is polyvinylidene fluoride (PVDF).

[0069] The anode present in the solid battery of the present invention preferably has a total thickness of 20 microns to 150 microns, more preferably 25 microns to 100 microns, and even more preferably 35 microns to 50 microns.

[0070] Preparation The solid battery of the present invention can be prepared by a conventional method well established in the field of solid lithium batteries. The method includes (i) preparing a cathode comprising a cathode active material containing Li ions, graphene, and optionally a binder; (ii) preparing an electrolyte; (v) preparing an anode; (vi) laminating the above cathode, electrolyte, and anode to form the above solid battery. and includes.

[0071] Preferably, the solid battery of the present invention is prepared by separately preparing the cathode and the anode. Preferably, the electrolyte is formed on the surface of the cathode to form a cathode / electrolyte structure. Preferably, the anode is laminated on the cathode / electrolyte structure.

[0072] Regarding the preparation of the cathode, the binder (if present), the cathode active material containing Li ions, and graphene are preferably mixed in a solvent to form a slurry, and then applied to the current collector and dried. Preferably, the binder (if present) and the solvent are premixed with graphene before adding the cathode active material containing Li ions.

[0073] Regarding the preparation of the anode, the anode active material (if present) and any optional components are mixed in a solvent to form a slurry, which is then applied to the current collector and dried.

[0074] Regarding the preparation of the electrolyte, the components are mixed with a solvent to form a slurry. Next, the electrolyte slurry is applied to the cathode (or anode) active material layer and dried.

[0075] Any mixing means, such as ultrasonic treatment, vacuum mixing, etc., can be used. Any application means, such as a doctor blade, etc., can be applied.

[0076] Subsequently, the cathode / solid electrolyte (or anode / solid electrolyte) is preferably laminated with the anode (or cathode) to form a solid-state battery. Optionally, the stacked cathode structure may be pressurized. Preferably, the solid-state battery of the present invention has a thickness of 70 microns to 750 microns, more preferably 100 microns to 600 microns, and even more preferably 235 microns to 550 microns.

[0077] Preferably, tabs are attached to each of the cathode current collector and the anode current collector. Preferably, the solid-state battery is packaged in a housing, preferably a pouch cell.

[0078] Pouch cell and method for preparing the same Preferably, the pouch cell includes the solid-state battery defined above and a packaging material that defines a pouch for enclosing the cathode, electrolyte, and anode. The pouch can be made of any conventional material in the art, such as laminated aluminum foil, etc.

[0079] Preferred pouch cells are multilayered. Preferred pouch cells include a plurality of cathodes, electrolytes, and anodes. Preferred pouch cells comprise from 2 to 20, more preferably from 5 to 15, and even more preferably from 6 to 12 cathodes. Preferred pouch cells include from 2 to 20, more preferably from 5 to 15, and even more preferably from 6 to 12 anodes. Preferred pouch cells include from 4 to 40, more preferably from 10 to 30, and even more preferably from 12 to 24 electrolytes.

[0080] Preferably, each cathode or cathode current collector has a protruding tab that extends outside the pouch. Preferably, the protruding tabs on the cathode / cathode current collectors are all aligned. Preferably, each anode or anode current collector has a protruding tab that extends outside the pouch. Preferably, the protruding tabs on the anode / anode current collectors are aligned. Optionally, each set of protruding tabs can be adhered to each other to provide a single thicker protruding tab for each of the plurality of cathodes and anodes. Electrical connections are made to the protruding tabs.

[0081] The pouch cell has a total weight based on the weight of the anode(s), cathode(s), electrolyte, and packaging material. It is desirable to minimize the weight contributed by elements that do not directly contribute to the function of the battery, such as the weight of inactive materials such as current collectors, binders, and additives, and the weight contributed by the packaging material.

[0082] Pouch cells have been prepared in various shapes and sizes conventionally. Preferably, the pouch cell is rectangular. Preferably, the pouch cell has dimensions of 30 mm to 250 mm × 30 mm to 250 mm, more preferably 40 mm to 200 mm × 40 mm to 200 mm, and even more preferably 40 mm to 60 mm × 40 mm to 60 mm. Optionally, the pouch cell is 1200 mm 2 ~62500 mm 2 and more preferably 1600 mm 2 ~6400 mm 2 in surface area.

[0083] The present invention relates to (i) manufacturing a battery as defined above, (ii) encapsulating the battery in a package that defines a pouch, and also relates to a method for manufacturing a pouch cell as defined above.

[0084] Performance Preferably, the solid-state battery, preferably in the form of a pouch cell, for example when tested according to the procedures described in the examples herein, achieves a capacity retention of at least 50%, more preferably at least 60%, even more preferably at least 70% after 40 cycles.

[0085] Preferably, the solid-state battery, preferably in the form of a pouch cell, for example when tested according to the procedures described in the examples herein, achieves a capacity retention of at least 50%, more preferably at least 60%, even more preferably at least 70% after 80 cycles.

[0086] Preferably, the solid-state battery, preferably in the form of a pouch cell, for example when tested according to the procedures described in the examples herein, achieves a capacity retention of at least 50%, more preferably at least 60%, even more preferably at least 70% after 100 cycles.

[0087] Preferably, the solid-state battery, preferably in the form of a pouch cell, operates at a C-rate of 0.1C to 3C. The C-rate is a unit used to measure the rate at which a battery is fully charged or discharged. For example, charging at a C-rate of 1C means that the battery is charged from 0% to 100% in 1 hour. A C-rate higher than 1C means faster charging. For example, a 3C rate is three times faster, so it is fully charged in 20 minutes.

[0088] Device The present invention also relates to a device comprising the solid battery as defined above, preferably in the form of a pouch cell. Pouch cells are attractive because they can use space efficiently, for example, achieving a packing efficiency of 90% to 95%, which is high compared to other types of batteries (e.g., cylindrical cells). Pouch cells also have the advantage of flexibility in size and shape and are generally lighter than other types of batteries by eliminating the metal casing.

[0089] Examples of devices comprising the solid battery of the present invention, preferably in the form of a pouch cell, include electric vehicles, portable electronic devices (e.g., mobile phones, tablets), robotics, aerospace devices, and stationary energy storage.

[0090] Solid Cathode Composition and Method for Preparing the Same The present invention also relates to (i) a cathode comprising a cathode active material containing Li ions, (ii) activated graphene, (iii) optionally a binder, and relates to a solid cathode composition.

[0091] Preferably, the cathode active material containing Li ions is as described above with respect to the cathode of the solid battery. Preferably, the activated graphene is as described above with respect to the cathode of the solid battery. Preferably, the solid cathode composition contains a binder. Preferably, the binder is as described above with respect to the cathode of the solid battery.

[0092] Preferably, the solid cathode composition contains 60% to 95% by weight, more preferably 65% to 90% by weight, and even more preferably 70% to 90% by weight of the cathode active material based on the total weight of the composition.

[0093] Preferably, the solid cathode composition contains 2.5% to 20% by weight, more preferably 5% to 17.5% by weight, and even more preferably 5% to 15% by weight of the activated graphene based on the total weight of the composition.

[0094] Preferably, the solid cathode composition contains 2.5 wt% to 20 wt%, more preferably 5 wt% to 17.5 wt%, and even more preferably 5 wt% to 15 wt% of a binder based on the total weight of the composition.

[0095] The present invention also relates to a method for manufacturing a solid cathode composition, which includes mixing a cathode active material containing Li ions, activated graphene, and optionally a binder. Any conventional mixing means can be used.

[0096] The present invention also relates to a solid cathode including the composition defined above.

[0097] The present invention also relates to a method for manufacturing the solid cathode defined above, which includes depositing a slurry of the solid cathode composition on a cathode current collector and drying it to form the cathode.

[0098] Finally, the present invention also relates to the use of the composition defined above for manufacturing a solid cathode or a solid battery.

[0099] Hereinafter, the present invention will be described with reference to the following non-limiting figures and examples.

Brief Description of the Drawings

[0100]

Figure 1

Figure 2

Figure 3

Examples

[0101] Materials Graphene powder was commercially obtained. It had an average particle size of less than 0.5 microns.

[0102] Polyvinylidene (PVDF) binder, N-methyl-2-pyrrolidone (NMP), LiNi 0.6 Mn 0.2 Co 0.2 O2 (NMC622), Li 1.4 Al 0.4 Ti 1.6 (PO4)3 (LATP), LiPF6 and aluminum foil were all commercially obtained.

[0103] Test methods Raman spectroscopy was performed using a Renishaw inVia instrument with 532 nm laser excitation.

[0104] TEM was performed using a Tecnai 20 at an acceleration voltage of 200 kV.

[0105] The specific surface area was determined by BET nitrogen absorption using a Quadrasorb EVO FVD-3 surface area and pore size analyzer.

[0106] The cycle charge / discharge test was performed by continuously charging / discharging the pouch cell at a 1C rate up to 150 cycles.

[0107] Preparation of activated graphene 2 g of graphene powder was mixed with 100 mL of 7 M KOH aqueous solution and stirred at 200 rpm for 3 hours, and then left to stand for at least 18 hours overnight. The graphene / KOH dispersion was filtered using filter paper (0.2 μm pore size) to remove the excess KOH solution. The filtered powder was dried in an oven at 65 °C for at least 18 hours. After drying, the powder was manually ground with a mortar and pestle for 5 minutes, and then placed in a tubular furnace at an argon flow rate of 150 sccm and a temperature of 800 °C (heating ramp rate of 10 °C / min). The sample was heated for 1 hour and then cooled under an argon flow. Next, the powder was removed, washed thoroughly with DI water, and filtered until the pH value reached 7. The activated graphene powder (a-GP) was heated in an oven at 65 °C for at least 18 hours, and then placed in a tubular furnace at an argon flow rate of 150 sccm and a temperature of 800 °C (10 °C / min). The sample was heated for 1 hour and then cooled under an argon flow. The average particle size of the activated graphene was less than 2 microns.

[0108] Comparison of Graphene and Activated Graphene Graphene powder and activated graphene powder were analyzed by TEM and Raman spectroscopy.

[0109] The Raman spectra are shown in Figure 1. D / I G The intensity ratio increased after activation (graphene: 0.83, activated graphene: 0.90), indicating that the introduction of pores into the graphene structure was successful. Furthermore, for the activated graphene, the intensity of the D’ peak increased significantly, and the height became approximately twice. The intensity of the D’ peak is known to be proportional to the presence of vacancy defects in graphene, thus providing further evidence that the porosity of the activated graphene has increased compared to the graphene starting material.

[0110] The TEM images are shown in Figure 2. The activated graphene powder has a cleaner and thinner morphology. The activated graphene powder is more flaky, i.e., it has a platelet structure.

[0111] The specific surface areas (using BET nitrogen adsorption) of the graphene powder and the activated graphene powder were also determined. These were 740 m 2 / g and 613.12 m 2 / g, respectively. Therefore, the activation process decreases the specific surface area of the graphene powder.

[0112] Preparation of the Cathode Composition and Cathode The polyvinylidene (PVDF) binder was dissolved by stirring in N-methyl-2-pyrrolidone (NMP) (the amount of NMP was 150% of the solid material) and heated at 80 °C for about 1 hour. Next, graphene (either powdered graphene or activated graphene powder) was stirred into the NMP solution containing PVDF. The mixture of NMP + PVDF + graphene was subjected to bath sonication for 20 minutes to 1 hour. Next, NMC was added and the mixture was placed in a vacuum mixer for 20 minutes (or until the material was completely dispersed). Additional NMP was added as needed to reduce the viscosity. The target viscosity was 5000 cP. The resulting slurry mixture was coated onto a current collector (carbon-coated aluminum) with a doctor blade and dried in a vacuum oven at 80 °C for 12 hours to form the cathode. The cathode had a wet film thickness of 200 μm.

[0113] Preparation of the Pouch Cell The solid electrolyte used was Li 1.4 Al 0.4 Ti 1.6 (PO4)3 (LATP). PVDF was dissolved by stirring in NMP (the amount of NMP was 120% of the solid material) and heated to 80 °C. LATP was added to the NMP + PVDF solution, stirred, and then placed in a vacuum mixer for 20 minutes (or until the material was completely dispersed). Next, the slurry was coated onto glass and dried in a vacuum oven at 80 °C for 12 hours. Once dried, the LATP film was removed from the glass, cut to the exact dimensions of the pouch cell, and then immersed in 1 M LiPF6 (EC / DMC), which is the battery electrolyte, for 12 hours. The wet film thickness of the solid electrolyte was 100 μm.

[0114] The solid electrolyte was stacked on the cathode. Next, the current collector (aluminum foil) of the anode was placed on top of the stack. Next, this stack was inserted into a polymer laminate aluminum pouch cell, which was vacuum heat-sealed at 180°C. The dimensions of the pouch cell were 50 mm × 40 mm.

[0115] Cyclic charge / discharge test Three different cathode compositions with different carbon sources (carbon black, graphene, and activated graphene) were assembled into pouch cells as described in the above preparation method. The pouch cell with the cathode containing carbon black functions as a baseline cell. The three pouch cells were continuously charged / discharged at a 1C rate up to 150 cycles, and the capacity was measured over the test period. The results are shown in Figure 3.

[0116] It can be seen that the baseline cell with the cathode containing carbon black has its capacity reduced to about 30% of its original capacity value during the first 40 cycles. The cathode containing activated graphene is reduced to about 80% of its capacity after 150 cycles, while the powdered graphene is reduced to approximately 60% after 150 cycles.

[0117] This experiment shows that pouch cells with graphene-containing cathodes can operate at a higher capacity for a much longer time than the corresponding pouch cells with carbon black-containing cathodes, and thus can be expected to have a longer operating life.

[0118] Furthermore, in the case of solid-state batteries, the 1C rate is relatively high compared to many literature reports that cite a value of 0.05C. This improvement may be due to the higher conductivity of graphene and the excellent mechanical stability that enables it to overcome any volume expansion and contraction during cycling.

Claims

1. (i)A cathode comprising a cathode active material containing Li ions, graphene, and optionally a binder, (ii)An electrolyte, (iii)An anode, preferably a lithium anode, A solid battery, preferably a pouch cell, comprising: The electrolyte is disposed between the cathode and the anode. A solid battery.

2. The battery according to claim 1, wherein the cathode contains a cathode active material containing Li ions selected from lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, lithium manganese oxide, lithium copper oxide, lithium vanadium oxide, lithium nickel composite oxide, lithium nickel cobalt aluminum oxide, lithium nickel manganese oxide, lithium manganese composite oxide, and Ni-Co-Mn ternary lithium metal oxide.

3. The cathode active material containing Li ions is a Ni-Co-Mn ternary lithium metal oxide (Li[Ni ｘ Co １－２ｘ Mn ｘ O] ２ (wherein x is greater than 0 and less than 0.5), NMC), the battery according to claim 2.

4. The battery according to any one of claims 1 to 3, wherein the cathode contains graphene in the form of platelets, preferably nanoplatelets.

5. The battery according to claim 4, wherein the cathode contains graphene in the form of nanoplatelets, and the cathode further contains a carbonaceous additive, preferably carbon black and / or carbon nanotubes.

6. The battery according to any one of claims 1 to 5, wherein the cathode contains graphene which is activated graphene.

7. The battery according to claim 6, wherein the activated graphene has an average particle size of 0.1 micron to 2 microns, more preferably 0.1 micron to 1 micron.

8. The battery according to any one of claims 1 to 7, wherein the cathode contains a binder.

9. The battery according to any one of claims 1 to 8, wherein the electrolyte contains an ionic liquid, an inorganic solid electrolyte, a solid polymer electrolyte, or a composite electrolyte, preferably a composite electrolyte.

10. The battery according to any one of claims 1 to 9, wherein the anode contains an anode current collector.

11. The battery according to any one of claims 1 to 10, wherein the anode contains lithium metal (for example, consisting only of lithium metal).

12. The battery according to claim 11, wherein the lithium is electrodeposited on the anode current collector during cycling.

13. The cathode is Li １．４ Al ０．４ Ti １．６ (PO ４ ) ３ (LATP), preferably a trace amount of LATP, and / or one or more carbonaceous additives, preferably carbon black and / or carbon nanotubes, and further includes the battery according to any one of claims 1 to 12.

14. (i)Preparing a cathode containing a cathode active material containing Li ions, graphene, and optionally a binder, (ii) preparing an electrolyte; (iii) preparing an anode; (iv) laminating the cathode, electrolyte, and anode to form the solid-state battery; A method for manufacturing a battery according to any one of claims 1 to 13, comprising the above steps.

15. (i) manufacturing the battery according to claim 14; (ii) enclosing the battery in a package defining a pouch; A method for manufacturing a pouch cell according to any one of claims 1 to 14, comprising the above steps.

16. Use of the solid-state battery according to any one of claims 1 to 13, preferably a pouch cell, in an electronic device.

17. A device, such as an electric vehicle, comprising the solid-state battery according to any one of claims 1 to 13, preferably a pouch cell.

18. (i) a cathode comprising a cathode active material containing Li ions; (ii) activated graphene; (iii) optionally a binder; A solid cathode composition comprising the above components.

19. A method for manufacturing the solid composition according to claim 18, comprising mixing a cathode active material containing Li ions, activated graphene, and, if present, a binder.

20. A solid cathode comprising the composition according to claim 18.

21. A method for manufacturing the solid cathode according to claim 20, comprising depositing a slurry of the solid cathode composition according to claim 18 on a cathode current collector and drying it to form the cathode.

22. Use of the composition according to claim 18 for manufacturing a solid cathode or a solid-state battery.

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