Electrode sheet and gel battery

Abstract

The present invention relates to an electrode sheet and a gel battery. The electrode sheet comprises a current collector and an active layer. The active layer comprises an active substance, a conductive agent, and a binder; the binder comprises a silk protein component. The present invention utilizes a natural silk protein component as a binder in the electrode sheet. After hot pressing and forming the battery, the electrolyte is fixed in the binder to produce a gel battery, thereby improving battery safety.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium ion batteries and relates to an electrode sheet, in particular to an electrode sheet and a gel battery. Background Art

[0002] Lithium-ion batteries have seen rapid development in the electric vehicle sector due to their high energy density, long cycle life, and environmental friendliness. As lithium battery energy density continues to increase, mass-produced aluminum-cased batteries now exceed 245Wh / kg, soft-pack batteries exceed 270Wh / kg, and developed soft-pack batteries have already surpassed 300Wh / kg. Despite achieving high energy density, lithium battery safety performance is declining, particularly in needle penetration tests. While low-energy-density lithium iron phosphate batteries pass, high-energy-density ternary high-nickel batteries quickly catch fire and explode. Improving battery cell safety is crucial to promoting the development of electric vehicles.

[0003] The safety of lithium batteries depends primarily on the decomposition of the cathode material at high temperatures and voltages, producing oxygen. This reacts with the flammable organic electrolyte and the anode, releasing large amounts of heat and potentially causing battery failure. To address this safety issue, much research has focused on the use of non-flammable solid-state electrolytes. However, due to factors such as poor ionic conductivity and high interfacial impedance, solid-state electrolytes are unlikely to be widely adopted in the near future.

[0004] At the same time, another solution is to reduce the amount of free electrolyte inside the battery, reduce its side reactions with the positive and negative electrode materials, reduce heat generation, and improve battery safety.

[0005] Based on this, US 5296318 discloses a gel battery comprising a lithium intercalation compound electrode and a flexible polymer intercalation electrolyte containing a lithium salt dissolved in a polymer compatible solvent. The preferred components include a third lithium manganese oxide compound positive electrode, a carbon negative electrode, and a polyvinylidene fluoride copolymer electrolyte layer containing a lithium salt solution of about 20% to 70% in a medium boiling solvent, such as ethylene carbonate, propylene carbonate, and dimethyl carbonate. The electrolyte layer can be in the form of a single separator or as a coating component of a multilayer battery structure to provide up to about 10 -3 s / cm ionic conductivity.

[0006] The gel battery uses PVDF-HFP as the binder for the positive and negative electrodes, and a porous PVDF-HFP separator. After the battery is assembled, an organic electrolyte is injected. During hot pressing, the electrolyte solidifies within the polymer, reducing the amount of free electrolyte and improving battery safety. However, the PVDF-HFP separator is expensive and complex to prepare, resulting in high battery costs and prohibitive for use in the cost-sensitive electric vehicle market.

[0007] Recent research on battery thermal runaway (Journal of Power Sources, 2017, 185-192) indicates that at temperatures of 240°C, the graphite anode reacts with fluorinated binders, releasing significant heat. Therefore, the use of fluorinated binders should be avoided as much as possible to improve battery safety. Furthermore, for high-energy-density batteries (>300Wh / kg), the silicon-based materials used in the anodes have a high expansion rate. Traditional PVDF binders lack polar functional groups and have weak bonding with silicon-based materials, making them ineffective in counteracting this expansion, resulting in poor battery cycling and safety performance.

[0008] Therefore, how to improve the use of binders in gel batteries, enhance battery safety, and reduce costs is an urgent problem to be solved in the field of lithium-ion battery technology. Summary of the Invention

[0009] To solve the above technical problems, the present invention provides an electrode sheet and a gel battery. A gel battery is prepared by using the protein component of a natural substance - silk - as a binder in the electrode sheet. After the battery is hot-pressed and formed, the electrolyte is fixed in the binder, thereby achieving the purpose of improving the battery safety performance.

[0010] To achieve this object, the present invention adopts the following technical solutions:

[0011] In a first aspect, the present invention provides an electrode sheet, comprising a current collector and an active layer, wherein the material of the active layer comprises an active material, a conductive agent, and a binder;

[0012] The binder includes the protein component of silk.

[0013] The present invention adopts the protein component of natural substance - silk as a binder in the electrode sheet, fixes the electrolyte in the binder after the battery is hot-pressed, and prepares a gel battery to achieve the purpose of improving the safety performance of the battery.

[0014] Preferably, the protein component of the silk includes sericin.

[0015] Preferably, the relative molecular weight of the sericin is 1-410 kDa, for example, 1 kDa, 10 kDa, 100 kDa, 200 kDa, 400 kDa or 410 kDa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0016] Preferably, the sericin comprises any one or a combination of at least two of serine, glycine or aspartic acid. Typical but non-limiting combinations include a combination of serine and glycine, a combination of glycine and aspartic acid, a combination of serine and aspartic acid, or a combination of serine, glycine and aspartic acid.

[0017] Sericin is a binder found in natural silk, rich in polarized functional groups such as hydroxyl and carboxyl groups, and possesses strong adhesion to silicon-based negative electrode materials. Furthermore, sericin does not contain fluorine, which prevents side reactions with negative electrode materials at high temperatures, thereby improving battery safety. Furthermore, sericin is stable within a voltage range of 0 to 5V and can be used in positive and negative electrodes as well as separators. It swells in the electrolyte, thereby immobilizing the electrolyte, reducing the amount of free electrolyte, and improving battery safety.

[0018] Preferably, the serine content in the sericin is 25-40% by mole percentage, for example, 25%, 30%, 35%, 38%, or 40%, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0019] Preferably, the glycine content in the sericin is 10-20% by mole percentage, for example, 10%, 12%, 14%, 16%, 18% or 20%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] Preferably, the aspartic acid content in the sericin is 15-30% by mole percentage, for example, 15%, 20%, 25%, 27% or 30%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0021] Preferably, the electrode sheet includes a positive electrode sheet.

[0022] Preferably, the materials in the active layer of the positive electrode sheet include a positive electrode active material, a conductive agent and a binder.

[0023] Preferably, the positive electrode active material includes a core-shell high-nickel ternary material.

[0024] Preferably, the molecular formula of the core material in the core-shell high nickel ternary material is LiNi x Co y M 1-x-yO2, wherein M is any one of Mn, Al, Mg, Zr, Ti, Cu, Fe, W or B, or a combination of at least two thereof. Typical but non-limiting combinations include the combination of Mn and Al, the combination of Al and Mg, the combination of Mg and Zr, the combination of Zr and Ti, the combination of Ti and Cu, the combination of Cu and Fe, the combination of Fe and W, the combination of W and B, the combination of Mn, Al and Mg, the combination of Al, Mg and Zr, the combination of Mg, Zr and Ti, the combination of Zr, Ti and Cu, the combination of Ti, Cu and Fe, the combination of Cu, Fe and W, the combination of Fe, W and B, the combination of Mn, Al, Mg, Zr, Ti and Cu, the combination of Al, Mg, Zr, Ti, Cu, Fe and W, the combination of Al, Mg, Zr, Ti, Cu and Fe, or the combination of Mn, Al, Mg, Zr, Ti, Cu, Fe, W and B. x+y=1, 0.7≤x≤1.0, for example, it can be 0.7, 0.8, 0.9, 0.95 or 1, and 0≤y≤0.3, for example, it can be 0, 0.05, 0.1, 0.15, 0.2, 0.25 or 0.3, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] Preferably, the molecular formula of the shell material in the core-shell high nickel ternary material is LiM z Mn 2-z O4, wherein M is any one of Ni, Cu, Cr or Co or a combination of at least two thereof, typical but non-limiting combinations include a combination of Ni and Cu, a combination of Cu and Cr, a combination of Cr and Co, a combination of Ni, Cu and Cr, a combination of Cu, Cr and Co, or a combination of Ni, Cu, Cr and Co, and 0.1≤z≤0.5, for example, it can be 0.1, 0.2, 0.3, 0.4 or 0.5, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] The high nickel in the core-shell high nickel ternary material of the present invention means that the proportion of nickel in the total metal exceeds 70%.

[0027] Preferably, in parts by mass, the positive electrode sheet includes 90 to 98 parts of positive electrode active material, for example, 90 parts, 92 parts, 94 parts, 96 parts or 98 parts, 1 to 5 parts of conductive agent, for example, 1 part, 2 parts, 3 parts, 4 parts or 5 parts, and 1 to 10 parts of binder, for example, 1 part, 2 parts, 4 parts, 6 parts, 8 parts or 10 parts, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] Preferably, the electrode sheet includes a negative electrode sheet.

[0029] Preferably, the materials in the active layer of the negative electrode sheet include a negative electrode active material, a conductive agent and a binder.

[0030] Preferably, the negative electrode active material includes any one or a combination of at least two of natural graphite, artificial graphite, mesophase carbon microbeads, silicon-carbon alloys, silicon oxide compounds or tin alloys. Typical but non-limiting combinations include a combination of natural graphite and artificial graphite, a combination of artificial graphite and mesophase carbon microbeads, a combination of mesophase carbon microbeads and silicon-carbon alloys, a combination of silicon-carbon alloys and silicon oxide compounds, a combination of silicon oxide compounds and tin alloys, a combination of natural graphite, artificial graphite and mesophase carbon microbeads, a combination of mesophase carbon microbeads, silicon-carbon alloys and silicon oxide compounds, a combination of silicon-carbon alloys, silicon oxide compounds and tin alloys, a combination of natural graphite, artificial graphite, mesophase carbon microbeads, silicon-carbon alloys and silicon oxide compounds, and a combination of artificial graphite, mesophase carbon microbeads, silicon-carbon alloys, silicon oxide compounds and tin alloys.

[0031] Preferably, the specific capacity of the negative electrode active material is 350 mAh / g or more, for example, it can be 350 mAh / g, 380 mAh / g, 400 mAh / g, 450 mAh / g or 500 mAh / g, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] Preferably, in parts by mass, the negative electrode sheet includes 90 to 98 parts of negative electrode active material, for example, 90 parts, 92 parts, 94 parts, 96 parts or 98 parts, 1 to 5 parts of conductive agent, for example, 1 part, 2 parts, 3 parts, 4 parts or 5 parts, and 1 to 10 parts of binder, for example, 1 part, 2 parts, 4 parts, 6 parts, 8 parts or 10 parts, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] In a second aspect, the present invention provides a gel battery, wherein the gel battery comprises the electrode sheet as described in the first aspect.

[0034] Preferably, the gel battery includes a positive electrode sheet, a negative electrode sheet and a separator.

[0035] Preferably, the diaphragm includes a diaphragm base layer and a diaphragm coating layer coated on the diaphragm base layer.

[0036] Preferably, the thickness of the diaphragm base layer is 3 to 16 μm, for example, 3 μm, 5 μm, 8 μm, 10 μm or 16 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0037] Preferably, the thickness of the diaphragm coating is 1 to 10 μm, for example, 1 μm, 2 μm, 4 μm, 6 μm, 8 μm or 10 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0038] Preferably, the material of the diaphragm base layer includes any one of polyethylene, polypropylene, polyethylene terephthalate (PET), non-woven fabric or aramid, or a combination of at least two of them. Typical but non-limiting combinations include a combination of polyethylene and polypropylene, a combination of polypropylene and PET, a combination of non-woven fabric and aramid, a combination of PET and non-woven fabric, a combination of PET and aramid, a combination of polyethylene, polypropylene and PET, or a combination of PET, non-woven fabric and aramid.

[0039] Preferably, the material of the diaphragm coating includes a coating material and a coating binder.

[0040] Preferably, the coating material comprises any one or a combination of at least two of NASCION type solid electrolyte, LISCION solid electrolyte, garnet type solid electrolyte, perovskite type solid electrolyte, sulfide electrolyte, polymer electrolyte, Al2O3, SiO2, ZrO2, TiO2, γ-AlOOH, BaTiO3 or Mg(OH)2, typical but non-limiting combinations include a combination of NASCION type solid electrolyte and LISCION solid electrolyte, a combination of LISCION solid electrolyte and garnet type solid electrolyte, a perovskite type solid electrolyte, a sulfide electrolyte, a polymer electrolyte, Al2O3, SiO2, ZrO2, TiO2, γ-AlOOH, BaTiO3 or Mg(OH)2, a typical but non-limiting combination includes a combination of NASCION type solid electrolyte and LISCION solid electrolyte, a combination of LISCION solid electrolyte and garnet type solid electrolyte, a perovskite type solid electrolyte, a sulfide electrolyte, a polymer electrolyte, Al2O3, SiO2, ZrO2, TiO2, γ-AlOOH, BaTiO3 or Mg(OH)2, a sulfide electrolyte, a polymer ... a polymer electrolyte, a polymer electrolyte, a polymer electrolyte The combination of solid electrolyte and sulfide electrolyte, the combination of sulfide electrolyte and polymer electrolyte, the combination of Al2O3, SiO2 and ZrO2, the combination of SiO2, ZrO2 and TiO2, the combination of TiO2, γ-AlOOH and BaTiO3, the combination of γ-AlOOH, BaTiO3 and Mg(OH)2, the combination of sulfide electrolyte, polymer electrolyte, Al2O3, SiO2, ZrO2 and TiO2, the combination of garnet-type solid electrolyte, perovskite-type solid electrolyte, sulfide electrolyte, polymer electrolyte, Al2O3 and SiO2.

[0041] The coating binder includes sericin.

[0042] Preferably, a binder coating is coated on the diaphragm coating.

[0043] Preferably, the material of the adhesive coating comprises sericin.

[0044] During the battery hot pressing process, the presence of the adhesive coating allows for better contact between the positive and negative electrodes and the diaphragm, reduces internal resistance, and improves safety performance.

[0045] Sericin has good film-forming properties and can prevent the increase of battery internal resistance.

[0046] Preferably, the thickness of the adhesive coating is 0.5 to 3 μm, for example, 0.5 μm, 1 μm, 1.5 μm, 2 μm or 3 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0047] Compared with the prior art, the present invention has at least the following beneficial effects:

[0048] (1) The present invention prepares a gel battery by using the protein component of natural substance - silk as a binder in the electrode sheet, and fixing the electrolyte in the binder after the battery is hot-pressed, thereby achieving the purpose of improving the safety performance of the battery.

[0049] (2) During the hot pressing process, the sericin in the positive and negative electrodes and coated in the separator forms a three-dimensional network structure, which effectively fixes the electrolyte, reduces the amount of free electrolyte in the system, and improves the safety performance of the battery.

[0050] (3) The adhesive coating containing sericin on the surface of the diaphragm and the diaphragm coating have an isolating effect on the positive and negative electrodes, so that the diaphragm will not shrink until the temperature is above 200°C, thus avoiding the occurrence of short circuit in the battery and improving safety performance.

[0051] (4) Sericin is a waste product of industrial silk, which greatly reduces the cost. At the same time, it is compatible with the diaphragm coating and drying process, making the coating more uniform, which is beneficial to protect the positive and negative active materials of the battery from direct contact and causing short circuits. DETAILED DESCRIPTION

[0052] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0053] Example 1

[0054] This embodiment provides a gel battery, which includes a positive electrode sheet, a negative electrode sheet, and a separator.

[0055] The positive electrode sheet includes a current collector and an active layer. The material of the active layer is positive electrode active material: conductive agent: binder = 96:2:2, in terms of mass fraction. The positive electrode active material is a core-shell high nickel ternary material, and the core material is LiNi 0.83 Co 0.12 Mn 0.05 , the shell material is LiNi 0.5 Mn 1.5O4, the binder is sericin with a relative molecular weight of 25 kDa. Calculated by mole percentage, the serine content in the sericin is 30%, the glycine content is 15%, and the aspartic acid content is 30%.

[0056] The negative electrode sheet includes a current collector and an active layer. The active layer comprises a negative electrode active material: conductive agent: binder ratio of 96:1.5:2.5, calculated by mass. The negative electrode active material is artificial graphite (with a gram capacity of 355 mAh / g), and the binder is sericin with a relative molecular weight of 25 kDa. Calculated by mole percentage, the serine content in the sericin is 30%, the glycine content is 15%, and the aspartic acid content is 30%.

[0057] The total thickness of the separator is 15 μm. It comprises a separator base, a separator coating applied to the base, and a binder coating applied to the separator coating. The separator base is made of polyethylene and is 9 μm thick. The separator coating is made of γ-AlOOH and sericin as a binder and is 2 μm thick. The binder coating is made of sericin and is 1 μm thick. The sericin in the separator is the same as that used in the positive and negative electrode sheets.

[0058] The gel battery is prepared by assembling a positive electrode sheet, a separator and a negative electrode sheet into a soft-pack battery, injecting 100g of electrolyte, performing high-temperature hot pressing at 60°C, and dividing the volume to obtain the gel battery.

[0059] Example 2

[0060] This embodiment provides a gel battery, which includes a positive electrode sheet, a negative electrode sheet, and a separator.

[0061] The positive electrode sheet includes a current collector and an active layer. The material of the active layer is positive electrode active material: conductive agent: binder = 96.5:2:1.5 by mass, wherein the positive electrode active material is a core-shell high nickel ternary material, and the core material is LiNi 0.88 Co 0.07 Mn 0.05 , the shell material is LiNi 0.5 Mn 1.5 O4, the binder is sericin with a relative molecular weight of 100 kDa. Calculated by mole percentage, the serine content in the sericin is 25%, the glycine content is 20%, and the aspartic acid content is 15%.

[0062] The negative electrode sheet includes a current collector and an active layer. The material of the active layer is negative electrode active material: conductive agent: binder = 95:2:3 by mass. The negative electrode active material is silicon carbon (SiO x / C) A composite material (gram capacity of 500 mAh / g), wherein the binder is sericin with a relative molecular weight of 100 kDa, and the sericin has a serine content of 25%, a glycine content of 20%, and an aspartic acid content of 15%, calculated in mole percentage.

[0063] The total thickness of the separator is 13 μm. It includes a separator base, a separator coating applied on the base, and a binder coating applied on the separator coating. The separator base is made of polypropylene and is 7 μm thick. The separator coating is made of a sulfide electrolyte and sericin as a binder and is 2 μm thick. The binder coating is made of sericin and is 1 μm thick. The sericin in the separator is the same as that used in the positive and negative electrode sheets.

[0064] The gel battery is prepared by assembling a positive electrode sheet, a separator and a negative electrode sheet into a soft-pack battery, injecting 100g of electrolyte, performing high-temperature hot pressing at 60°C, and dividing the volume to obtain the gel battery.

[0065] Example 3

[0066] This embodiment provides a gel battery, which differs from the embodiment 1 only in that the relative molecular weight of the sericin is 0.8 kDa.

[0067] Example 4

[0068] This embodiment provides a gel battery, which differs from the embodiment 1 only in that the relative molecular weight of the sericin is 420 kDa.

[0069] Example 5

[0070] This embodiment provides a gel battery, which differs from the first embodiment only in that the positive electrode active material is replaced with a non-core-shell ternary positive electrode material NCM811 of equal mass.

[0071] Example 6

[0072] This embodiment provides a gel battery, which differs from the first embodiment only in that the positive electrode active material is replaced with a non-core-shell ternary positive electrode material NCM622 of equal mass.

[0073] Example 7

[0074] This embodiment provides a gel battery, which differs from the embodiment 1 only in that the thickness of the binder coating is 0.4 μm and the total thickness of the separator is 13.8 μm.

[0075] Example 8

[0076] This embodiment provides a gel battery, which differs from the embodiment 1 only in that the thickness of the binder coating is 3.5 μm and the total thickness of the separator is 20 μm.

[0077] Example 9

[0078] This embodiment provides a gel battery, which differs from the embodiment 1 only in that the binder in the separator coating is PVDF 5130.

[0079] Example 10

[0080] This embodiment provides a gel battery, which differs from the embodiment 1 only in that there is no binder coating in the separator.

[0081] Example 11

[0082] This embodiment provides a gel battery, which differs from embodiment 1 only in that the sericin in the positive electrode sheet is replaced with PVDF 5130 of equal mass.

[0083] Example 12

[0084] This embodiment provides a gel battery, which differs from the embodiment 1 only in that the sericin in the negative electrode sheet is replaced with PVDF 5130 of equal mass.

[0085] Comparative Example 1

[0086] This comparative example provides a battery, which includes a positive electrode sheet, a negative electrode sheet, and a separator.

[0087] The positive electrode sheet includes a current collector and an active layer. The material of the active layer is positive electrode active material: conductive agent: binder = 96:2:2, in terms of mass fraction. The positive electrode active material is a core-shell high nickel ternary material, and the core material is LiNi 0.83 Co 0.12 Mn 0.05 , the shell material is LiNi 0.5 Mn 1.5 O4, the binder is PVDF 5130.

[0088] The negative electrode sheet includes a current collector and an active layer. The material of the active layer is negative electrode active material: conductive agent: binder = 96:1.5:2.5 by mass. The negative electrode active material is artificial graphite (gram capacity is 355 mAh / g), and the binder is CMC and SBR.

[0089] The total thickness of the diaphragm is 15 μm. The diaphragm includes a diaphragm base layer, a diaphragm coating applied on the diaphragm base layer, and an adhesive coating applied on the diaphragm coating layer, wherein the material of the diaphragm base layer is polyethylene with a thickness of 9 μm; the material of the diaphragm coating layer is γ-AlOOH and PVDF 5130 as an adhesive with a thickness of 2 μm; the material of the adhesive coating layer is PVDF5130 with a thickness of 1 μm.

[0090] The battery is prepared by assembling a positive electrode sheet, a separator and a negative electrode sheet into a soft-pack battery, injecting 100g of electrolyte, performing high-temperature hot pressing at 60°C, and dividing the capacity to obtain the battery.

[0091] Comparative Example 2

[0092] This embodiment provides a battery, which includes a positive electrode sheet, a negative electrode sheet, and a separator.

[0093] The positive electrode sheet includes a current collector and an active layer. The material of the active layer is positive electrode active material: conductive agent: binder = 96.5:2:1.5 by mass, wherein the positive electrode active material is a core-shell high nickel ternary material, and the core material is LiNi 0.88 Co 0.07 Mn 0.05 , the shell material is LiNi 0.5 Mn 1.5 O4, the binder is PVDF 5130.

[0094] The negative electrode sheet includes a current collector and an active layer. The material of the active layer is negative electrode active material: conductive agent: binder = 95:2:3 by mass. The negative electrode active material is silicon carbon (SiO x / C) composite material (gram capacity of 500 mAh / g), wherein the binder is polyacrylic acid.

[0095] The total thickness of the diaphragm is 13 μm. The diaphragm includes a diaphragm base layer, a diaphragm coating applied on the diaphragm base layer, and an adhesive coating applied on the diaphragm coating layer, wherein the material of the diaphragm base layer is polypropylene with a thickness of 7 μm; the material of the diaphragm coating layer is a sulfide electrolyte and PVDF 5130 as a binder with a thickness of 2 μm; the material of the adhesive coating layer is PVDF 5130 with a thickness of 1 μm.

[0096] The battery is prepared by assembling a positive electrode sheet, a separator and a negative electrode sheet into a soft-pack battery, injecting 100g of electrolyte, performing high-temperature hot pressing at 60°C, and dividing the capacity to obtain the battery.

[0097] The gel cells and batteries obtained above were tested.

[0098] To test the amount of free electrolyte, discharge the battery to 2.7V and weigh its mass (M1). Open a hole in one side of the aluminum-plastic film surrounding the battery and apply 5 tons of pressure to the surface of the cell for 1 minute. Discard any excess electrolyte and weigh the remaining battery mass (M2). Calculate the mass of the free electrolyte as M1 minus M2.

[0099] The acupuncture safety performance test is carried out in accordance with the requirements for acupuncture tests in GB / T 31485-2015.

[0100] To test the cycling performance, the battery cell was charged at 0.5C and discharged at 1C in the range of 2.75-4.25V at room temperature to calculate its capacity retention rate after 100 cycles.

[0101] Table 1

[0102]

[0103]

[0104] From the data in Table 1, we can see that:

[0105] As can be seen from Examples 1 and 2, the present invention uses the protein component of a natural substance, silk, as a binder in the electrode sheet, and fixes the electrolyte in the binder after the battery is hot-pressed to prepare a gel battery, thereby achieving the purpose of improving the battery safety performance.

[0106] The side groups on sericin have a greater impact. When the side groups are small, increasing the length of the side groups can reduce the intermolecular force, thereby reducing the bonding strength. When the side groups reach a certain length, they begin to crystallize. Increasing the length of the side chains can increase the intermolecular force, thereby increasing the bonding strength.

[0107] If the thickness of the sericin coating is too large, the battery impedance will increase; if the thickness is too small, it will not be conducive to the fixation of the electrolyte in the binder, and the amount of free electrolyte will increase, resulting in poor cycle performance and safety performance.

[0108] If sericin is not used in the positive and negative electrodes, the contact resistance between the positive and negative electrodes and the diaphragm will increase, reducing safety performance; if sericin is not used in the diaphragm, the amount of electrolyte in the gel battery will be reduced, the amount of free electrolyte will increase, and the cycle performance and safety performance will be reduced.

[0109] While the present invention uses the above-described embodiments to illustrate the detailed process equipment and process flow of the present invention, the present invention is not limited to the above-described detailed process equipment and process flow, and does not necessarily rely on the above-described detailed process equipment and process flow for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent replacements for raw materials in the products of the present invention, additions of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A gel battery, characterized in that: The gel battery contains electrode sheets; The electrode sheets include a positive electrode sheet and a negative electrode sheet; The gel battery further includes a separator; The diaphragm includes a diaphragm base layer and a diaphragm coating layer coated on the diaphragm base layer; The thickness of the diaphragm base layer is 3 to 16 μm; the thickness of the diaphragm coating layer is 1 to 10 μm; The materials of the diaphragm coating include coating materials and coating binders; The coating binder includes sericin; The electrode sheet includes a current collector and an active layer, and the material of the active layer includes an active material, a conductive agent and a binder; The binder includes the protein component of silk.

2. The gel battery according to claim 1, characterized in that The coating material includes any one of NASCION solid electrolyte, LISCION solid electrolyte, garnet solid electrolyte, perovskite solid electrolyte, sulfide electrolyte, polymer electrolyte, Al2O3, SiO2, ZrO2, TiO2, γ-AlOOH, BaTiO3 or Mg(OH)2, or a combination of at least two thereof.

3. The gel battery according to claim 1, characterized in that An adhesive coating is applied on the diaphragm coating; the material of the adhesive coating includes sericin; The thickness of the adhesive coating is 0.5 to 3 μm.

4. The gel battery according to claim 1, characterized in that The protein component of the silk includes sericin; The relative molecular weight of the sericin is 1 to 410 kDa; The sericin protein includes any one of serine, glycine or aspartic acid or a combination of at least two thereof; The serine content in the sericin is 25-40% by mole percentage; Calculated by mole percentage, the content of glycine in the sericin is 10-20%; Calculated by mole percentage, the content of aspartic acid in the sericin is 15-30%.

5. The gel battery according to claim 1, characterized in that The materials in the active layer of the positive electrode sheet include positive electrode active material, conductive agent and binder; The positive electrode active material includes a core-shell high-nickel ternary material; The molecular formula of the core material in the core-shell high nickel ternary material is LiNi x Co y M 1-x-y O2, wherein M is any one of Mn, Al, Mg, Zr, Ti, Cu, Fe, W or B, or a combination of at least two thereof, and x+y=1, 0.7≤x≤1.0, and 0≤y≤0.3; The molecular formula of the shell material in the core-shell high nickel ternary material is LiM z Mn 2-z O4, wherein M is any one of Ni, Cu, Cr or Co or a combination of at least two thereof, and 0.1≤z≤0.

5.

6. The gel battery according to claim 5, characterized in that The positive electrode sheet contains 90 to 98 parts of positive electrode active material by mass. 1 to 5 parts conductive agent 1 to 10 parts of binder.

7. The gel battery according to claim 1, characterized in that The electrode sheet includes a negative electrode sheet; The materials in the active layer of the negative electrode sheet include negative electrode active material, conductive agent and binder; The negative electrode active material includes any one or a combination of at least two of natural graphite, artificial graphite, mesophase carbon microbeads, silicon-carbon alloy, silicon-oxygen compound or tin alloy; The specific capacity of the negative electrode active material is greater than 350 mAh / g.

8. The gel battery according to claim 7, characterized in that: The negative electrode sheet contains 90 to 98 parts of negative electrode active material by mass. 1 to 5 parts conductive agent 1 to 10 parts of binder.

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