Organic-inorganic composite film and lithium battery

Abstract

To provide an organic-inorganic composite film for improving a reversible capacity of a lithium battery after several cycles and a lithium battery including the organic-inorganic composite film.SOLUTION: A lithium battery includes: a positive electrode plate; a negative electrode plate; an electrolyte disposed between the positive electrode plate and the negative electrode plate; a separator disposed in the electrolyte; and an organic-inorganic composite film disposed on a surface of the positive electrode plate, a surface of the negative electrode plate, a surface of the separator, or a combination thereof. The organic-inorganic composite film includes: 100 parts by weight of clay; 3 to 35 parts by weight of lignocellulose; and 25 to 270 parts by weight of first binder.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The technical field relates to lithium batteries, and more particularly to organic-inorganic composite films in lithium batteries. [Background technology]

[0002] The actual capacity per gram of graphite anode material is close to its theoretical value (372 mAh / g). To further increase the capacity per gram, materials with higher capacities per gram, such as silicon particles, silicon oxide, and lithium metal, can be added. Current mainstream technology involves the addition of silicon anode materials, such as silicon oxide and silicon particles. Lithium can form an alloy with silicon, rather than simply being intercalated between graphite layers. Therefore, compared to conventional graphite, the introduction of silicon as an anode material significantly increases the capacity per gram. For example, the theoretical capacities per gram of silicon oxide material and silicon particles are 1970 mAh / g and 4190 mAh / g, respectively. However, the alloying process can cause dramatic volume expansion; for example, silicon oxide and silicon particles can expand by approximately 120% and 300%, respectively. Additionally, the initial coulombic efficiency of silicon is lower than that of graphite. Volume expansion can lead to structural cracks that can disrupt the conductive pathway network, thereby shortening cycle life and seriously affecting battery quality. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Taiwan Patent No. 200733878A Specification [Patent Document 2] Taiwan Patent No. 200724603A Specification Summary of the Invention [Problem to be solved by the invention]

[0004] Novel materials and structural designs are needed to improve the reversible capacity of lithium batteries (containing silicon anodes) after several cycles. [Means for solving the problem]

[0005] One embodiment of the present disclosure provides an organic-inorganic composite membrane comprising 100 parts by weight of clay, 3 to 35 parts by weight of lignocellulose, and 25 to 270 parts by weight of a first binder.

[0006] One embodiment of the present disclosure provides a lithium battery including a positive electrode plate, a negative electrode plate, an electrolyte disposed between the positive electrode plate and the negative electrode plate, a separator disposed in the electrolyte, and an organic-inorganic composite membrane disposed on a surface of the positive electrode plate, a surface of the negative electrode plate, a surface of the separator, or a combination thereof. [Effects of the Invention]

[0007] The lithium battery containing the organic-inorganic composite film has better reversible capacity after several cycles.

[0008] This will be described in detail in the following embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0009] In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a more thorough understanding of the disclosed embodiments. However, it will be apparent that one or more embodiments may be practiced without these specific details.

[0010] One embodiment of the present disclosure provides an organic-inorganic composite membrane comprising 100 parts by weight of clay, 3 to 35 parts by weight of lignocellulose, and 25 to 270 parts by weight of a first binder. In some embodiments, the lignocellulose may be original (e.g., unmodified) lignocellulose or modified lignocellulose. Lignocellulose is primarily composed of cellulose, hemicellulose, and lignin. Lignocellulose contains multiple polar groups, such as alcohols, aldehydes, ketones, acids, phenolics, esters, and tannins. Therefore, lignocellulose can capture divalent metal ions. The organic-inorganic composite membrane can be used in energy storage devices. When used in a lithium battery, the organic-inorganic composite membrane can prevent divalent metal ions from being released from the positive electrode plate of the lithium battery, passing through the separator, and being chemically reduced and deposited as crystal nuclei on the negative electrode plate. The crystal nuclei tend to cause problems with lithium dendrites.

[0011] The layered structure of clay allows for efficient transport of monovalent ions, allowing lithium ions to pass smoothly through the clay without affecting the operation of the lithium battery. If the amount of clay is too large, the clay will not be uniformly dispersed in the organic-inorganic composite, resulting in poor performance of the organic-inorganic composite film. If the amount of clay is too small, the volume expansion and degradation of the negative electrode will not be effectively suppressed. In some embodiments, the natural clay includes montmorillonite clay, vermiculite clay, another clay with high cationic conductivity, or a combination thereof. In some embodiments, the clay diameter may be 1 micrometer or less. For example, the clay diameter may be between 0.02 micrometers and 1 micrometer. If the clay diameter is too large, it will be difficult to uniformly disperse the clay in the composite solution.

[0012] In some embodiments, the first binder effectively binds the lignocellulose and clay to form a homogeneous mixture. Using too much of the first binder can result in too little lignocellulose and / or clay, resulting in the problems described above. Using too little of the first binder can result in delamination or peeling of the lignocellulose and clay in the organic-inorganic composite. The first binder can include polyacrylic acid, polyacrylonitrile, polyethylene carbonate, polyacrylamide, polyethylene glycol, polysiloxane, polyamide, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyvinylpyrrolidone, or a combination thereof.

[0013] In some embodiments, the modified lignocellulose may be lignocellulose modified with a chelating agent. In some embodiments, the weight ratio of lignocellulose to chelating agent is 100:0.1 to 100:20. Lignocellulose modified with a chelating agent can further enhance the organic-inorganic composite membrane's ability to capture divalent metal ions and prevent lithium dendrite problems. If the amount of chelating agent is too small, the effect will be similar to that of lignocellulose not modified with a chelating agent. If the amount of chelating agent is too large, electrical properties will be impaired. In some embodiments, the chelating agent comprises N,N-bis(5-pyridoxal phosphate)-ethylenediamine-N,N'-diacetic acid, N,N'-bis(3-hydroxy-2-methyl-5-phosphonylmethyl)-4-pyridylmethyl)ethylenediamine-N,N'-diacetic acid (DPDP), diethylenetriaminepentaacetic acid (DTPA), cyclohexanediaminetetraacetic acid (DCTA), N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine (EDTP), 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), ethylenediaminetetraacetic acid (EDTA), 1-oxa-4,7,10-triazacyclododecanetriacetic acid (DOXA), 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid trisodium salt (DO3A), or a combination thereof.

[0014] In some embodiments, the organic-inorganic composite film may further include 0.1 to 15 parts by weight of an oxide nanopowder. The oxide nanopowder can further increase the mechanical strength of the organic-inorganic composite film and support the clay layer structure. If the amount of oxide nanopowder is too small, the effect will be similar to that of an organic-inorganic composite film without the oxide nanopowder. If the amount of oxide nanopowder is too large, an excessive amount of the oxide nanopowder will be distributed outside the clay layer structure, and too much of the inorganic material will easily peel off due to insufficient adhesion. As a result, the battery will lose its protective effect. In one embodiment, the oxide nanopowder includes aluminum oxide, silicon oxide, boehmite, titanium oxide, magnesium oxide, or a combination thereof, and the oxide nanopowder may have the configuration of particles, fibers, wires, or nets. In some embodiments, the oxide nanopowder has a diameter of 1 nm to 200 nm. If the oxide nanopowder diameter is too large, the oxide nanopowder will not be able to effectively disperse in the clay layer structure, resulting in the inability to support it and making it difficult to uniformly distribute the composite solution. This affects the conductivity of lithium ions, increases the probability of lithium dendrite formation, and reduces the effectiveness of capturing divalent ions. If the diameter of the oxide nanopowder is too small, the oxide nanopowder will aggregate because it is difficult to disperse.

[0015] In some embodiments, the thickness of the organic-inorganic composite film can be 0.1 micrometers to 10 micrometers depending on the application. When the organic-inorganic composite film is used in a lithium battery, if the organic-inorganic composite film is too thick, the ionic conductivity decreases, the impedance increases, and electrical degradation, such as a decrease in battery capacity, occurs. If the organic-inorganic composite film is too thin, the active material is not protected, delamination occurs, and the chelating effect decreases.

[0016] One embodiment of the present disclosure provides a lithium battery including a positive electrode plate, a negative electrode plate, an electrolyte disposed between the positive electrode plate and the negative electrode plate, a separator disposed in the electrolyte, and an organic-inorganic composite membrane disposed on a surface of the positive electrode plate, a surface of the negative electrode plate, a surface of the separator, or a combination thereof. For example, the organic-inorganic composite film may be (1) formed only on the surface of the negative electrode plate (with or without direct contact) and disposed between the negative electrode plate and the separator, (2) formed only on the surface of the positive electrode plate (with or without direct contact) and disposed between the positive electrode plate and the separator, (3) formed only on one surface of the separator (with or without direct contact) and disposed between the separator and the negative electrode plate, (4) formed only on one surface of the separator (with or without direct contact) and disposed between the separator and the positive electrode plate, or (5) a combination of these (e.g., formed on the surface of the negative electrode plate, the surface of the positive electrode plate, and two surfaces of the separator (with or without direct contact)). Regardless of where the organic-inorganic composite film is located, the performance of the lithium battery can be improved. In fact, the electrolyte may corrode the positive electrode plate, dissociating divalent metal ions such as manganese ions, cobalt ions, or nickel ions. If a lithium battery does not include an organic-inorganic composite film, divalent metal ions can permeate the separator and deposit on the negative electrode plate, which can easily form lithium dendrites there, degrading the performance of the lithium battery. In some embodiments, the negative electrode plate can be a silicon negative electrode plate. When an organic-inorganic composite film is formed on the silicon negative electrode plate, it helps to suppress the volume expansion of the silicon negative electrode plate during charge / discharge cycles, reducing battery degradation and extending the cycle life of the battery. In some embodiments, the negative electrode plate can be a graphite negative electrode plate.

[0017] In some embodiments, the positive electrode plate includes a lithium metal composite oxide, a first conductive additive, and a second binder, and the lithium metal composite oxide includes LiMnO2, LiMn2O4, LiCoO2, Li2Cr2O7, Li2CrO4, LiNiO2, LiFeO2, LiNi x Co 1-xO2 (0 < x < 1), LiMPO4 (M is a transition metal), LiMn 0.5 Ni 0.5 O2, LiNi x Co y Mn z O2 (x + y + z = 1), LiNi x Co y Al z O2 (x + y + z = 1), LiMc 0.5 Mn 1.5 O4 (Mc is a divalent metal), or a combination thereof is included, the first conductive additive includes carbon black, graphite, graphene, carbon nanotubes, acetylene black, nickel powder, aluminum powder, titanium powder, stainless steel powder, or a combination thereof, and the second binder includes polyvinylidene fluoride, styrene-butadiene rubber, polyamide, melamine resin, or a combination thereof.

[0018] For example, the positive electrode plate may be manufactured as follows. For example, 65 to 75 parts by weight of a lithium metal composite oxide, which is a lithium nickel cobalt manganese metal oxide, 25 to 35 parts by weight of a solvent, such as N-methylpyrrolidone (NMP), 2 to 5 parts by weight of conductive carbon black as a conductive additive, and 0.1 to 1 part by weight of carbon nanotubes are stirred and mixed for several hours. Next, a NMP solution of PVDF (containing 1 to 5 parts by weight of PVDF) is added to the mixture, and stirring and mixing are continued for several hours to obtain a positive electrode slurry. The positive electrode slurry is applied onto a current collector (for example, an aluminum foil), heated to 150 °C for drying, and then rolled to form a positive electrode active layer with a thickness of 51 to 65 micrometers on the current collector. Thus, the positive electrode plate is completed. It should be understood that the steps of the above process are merely for illustration, and those skilled in the art can adjust the composition of the materials and the manufacturing method of the positive electrode plate if necessary, and are not limited to the above description.

[0019] In some embodiments, the separator includes polyethylene (PE), polypropylene (PP), or a multilayer structure thereof (for example, PE / PP / PE).

[0020] In some embodiments, the silicon negative electrode plate includes a silicon negative electrode active material, a second conductive additive, and a third binder. The silicon negative electrode active material includes silicon oxide, a mixture of silicon and graphite, or a combination thereof. The second conductive additive includes carbon black, graphite, graphene, carbon nanotubes, acetylene black, nickel powder, aluminum powder, titanium powder, stainless steel powder, or a combination thereof. The third binder includes polyvinylidene fluoride, styrene butadiene rubber, polyamide, melamine resin, or a combination thereof.

[0021] For example, a silicon negative electrode plate can be prepared as follows: 40 to 55 parts by weight of silicon oxide / graphite negative electrode active material SiOC, 50 to 60 parts by weight of deionized water, 0.1 to 1 part by weight of conductive carbon black (e.g., Super-P or KS6) or carbon nanotubes as a conductive additive, 0.2 to 2 parts by weight of styrene-butadiene rubber as a binder, and 0.2 to 2 parts by weight of sodium carboxymethyl cellulose (CMC) as a thickener are mixed and stirred for several hours to obtain a silicon negative electrode slurry. The silicon negative electrode slurry is then applied to a current collector (e.g., copper foil), heated to 50 to 90°C to dry, and then rolled to form a silicon negative electrode active layer with a thickness of 55 to 56 micrometers on the current collector. It should be understood that the above process steps are merely illustrative, and that those skilled in the art can adjust the material composition and preparation method of the silicon negative electrode plate as necessary, and are not limited to the above description.

[0022] In some embodiments, the graphite negative electrode plate includes a graphite negative electrode active material, a second conductive additive, and a third binder. The graphite negative electrode active material includes artificial graphite, natural graphite, modified graphite, graphitized mesocarbon microbeads (MCMB), or a combination thereof. The second conductive additive includes carbon black, graphene, carbon nanotubes, acetylene black, nickel powder, aluminum powder, titanium powder, stainless steel powder, or a combination thereof. The third binder includes polyvinylidene fluoride, styrene butadiene rubber, polyamide, melamine resin, or a combination thereof.

[0023] The electrolyte may be liquid, gel, or quasi-solid. For example, the liquid electrolyte solution consists mainly of an organic solvent, a lithium salt, and other applicable additives. The organic solvent may be γ-butyrolactone (GBL), ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), propyl acetate (PA), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), or a combination thereof. The lithium salt may be LiPF6, LiBF4, LiAsF6, LiSbF6, LiClO4, LiAlCl4, LiGaCl4, LiNO3, LiC(SO2CF3)3, LiN(SO2CF3)2, LiSCN, LiO3SCF2CF3, LiC6F5SO3, LiO2CCF3, LiSO3F, LiB(C6H5)4, LiCF3SO3, LiB(C2O4)2, or a combination thereof.

[0024] The present invention will be described in detail below with reference to exemplary embodiments, so that those skilled in the art can easily understand the present invention. However, the present invention is not limited to the exemplary embodiments shown herein, and the present invention may be embodied in various forms. [Example]

[0025] In the following examples, a positive electrode plate was fabricated as follows: 67.6 parts by weight of lithium nickel cobalt manganese metal oxide (S85E, available from LNMC, Ronbay) as a lithium metal composite oxide, 30 parts by weight of N-methylpyrrolidone (NMP), 1 part by weight of conductive carbon black Super-P (available from TAIWAN MAXWAVE CO., LTD.) as a conductive additive, and 0.25 parts by weight of single-walled carbon nanotubes (SWCNT, available from Tuball) were mixed and stirred for several hours. Next, a PVDF NMP solution (containing 1.5 parts by weight of PVDF) (Solef® 5130, available from Solvay) was added to the mixture, followed by stirring for several hours to obtain a positive electrode slurry. The positive electrode slurry was applied to aluminum foil, dried at 150°C, and then rolled to form a 60-micrometer-thick positive electrode active layer on the aluminum foil. This completed positive electrode plate was thus obtained.

[0026] In the following examples, silicon negative electrode plates were prepared as follows: 41.6 parts by weight of silicon oxide / graphite negative electrode active material SiOC 500 (S500A, commercially available from BTR), 56.9 parts by weight of deionized water, 0.129 parts by weight of conductive carbon black Super-P (commercially available from TAIWAN MAXWAVE CO., LTD.) as a conductive additive, 0.1 parts by weight of carbon nanotubes (Water, commercially available from Tuball), 0.546 parts by weight of styrene-butadiene rubber (SBR, 451B, commercially available from Zeon) as a binder, and 0.56 parts by weight of sodium carboxymethyl cellulose (CMC) as a thickener were mixed and stirred for several hours to form a silicon negative electrode slurry. The silicon negative electrode slurry was applied to copper foil, dried at 90°C, and then rolled to form a 55-micrometer-thick negative electrode active layer on the copper foil. The silicon negative electrode plate was thus completed.

[0027] In the following examples, the separator was a tri-layer separator 2320 (PP / PE / PP, commercially available from Celgard). The FEC-containing electrolyte for NMC811 / SiOC was commercially available from Shenzhen Capchem Technology Co., Ltd.

[0028] In the following examples, lignocellulose was prepared as follows: Bamboo fiber was crushed and sintered at a high temperature of 600°C for 5 hours to carbonize it, and then crushed again to form lignocellulose. Lignocellulose modified with a chelating agent was prepared as follows: 0.9 parts by weight of DTPA (commercially available from Mitsubishi Chemical, 99%) and 9 parts by weight of lignocellulose were mixed in 90.1 parts by weight of ethanol (99.9%) under nitrogen, then placed in an oven at 110°C to dry completely, and then crushed to obtain lignocellulose modified with a chelating agent.

[0029] Comparative Example 1 1.5 g of aluminum oxide (UR-IALU001, commercially available from UNI-ONWARD Co., diameter approximately 13 nm) and 13.5 g of montmorillonite clay (commercially available from Southern Clay, diameter less than 0.5 micrometers) were dispersed in 185 g of acetone. 35 g of PVDF powder (Kynar HSV900, commercially available from ARKEM) was added to the dispersion, and the mixture was stirred to completely disperse the powder, yielding an organic-inorganic composite coating material.

[0030] The organic-inorganic composite coating material was applied to a silicon negative electrode plate and then dried, forming an organic-inorganic composite film on the surface of the silicon negative electrode plate. The positive electrode plate and silicon negative electrode plate (containing the organic-inorganic composite film on their surfaces) were each cut to an appropriate size, and a separator was placed between the positive electrode plate and the silicon negative electrode plate. The organic-inorganic composite film was placed between the silicon negative electrode plate and the separator. Electrolyte was injected into the space between the positive electrode plate and the silicon negative electrode plate, so that the separator was immersed in the electrolyte. The structure was left to stand for one day to allow the electrolyte to diffuse and impregnate the positive and negative electrodes. The structure was then charged to 4.2 V at a current of 0.1 C and then discharged to 2.5 V at a current of 0.1 C. This charge / discharge cycle was repeated three times to complete the formation process, resulting in a completed lithium battery.

[0031] The discharge capacity of the battery after one charge / discharge cycle (0.1C / 0.1C) was 183.8mAh / g. Further cycle tests were performed as follows: the battery was charged to 4.2V at a current of 0.5C and then discharged to 2.5V at a current of 0.5C to complete one cycle. The discharge capacity of the battery after one charge / discharge cycle (0.5C / 0.5C) was 149mAh / g (defined as 100% reversible capacity). The discharge capacity of the battery after 100 charge / discharge cycles (0.5C / 0.5C) was 118mAh / g (79.6% reversible capacity). The discharge capacity of the battery after 300 charge / discharge cycles (0.5C / 0.5C) was 91.5mAh / g (61.3% reversible capacity). The discharge capacity of the battery after 500 charge / discharge cycles (0.5C / 0.5C) was 68.78 mAh / g (46% reversible capacity).

[0032] Example 1 1.5 g of lignocellulose and 13.5 g of montmorillonite clay (commercially available from Southern Clay, diameter less than 0.5 micrometers) were dispersed in 185 g of acetone. 35 g of PVDF powder (Kynar HSV900, commercially available from ARKEM) was added to the dispersion, and the mixture was stirred to completely disperse the mixture, yielding an organic-inorganic composite coating material.

[0033] The organic-inorganic composite coating material was applied to a silicon negative electrode plate and then dried, forming an organic-inorganic composite film on the surface of the silicon negative electrode plate. The positive electrode plate and silicon negative electrode plate (containing the organic-inorganic composite film on their surfaces) were each cut to an appropriate size, and a separator was placed between the positive electrode plate and the silicon negative electrode plate. The organic-inorganic composite film was placed between the silicon negative electrode plate and the separator. Electrolyte was injected into the space between the positive electrode plate and the silicon negative electrode plate, so that the separator was immersed in the electrolyte. The structure was left to stand for one day to allow the electrolyte to diffuse and impregnate the positive and negative electrodes. The structure was then charged to 4.2 V at a current of 0.1 C and then discharged to 2.5 V at a current of 0.1 C. This charge / discharge cycle was repeated three times to complete the formation process, resulting in a completed lithium battery.

[0034] The discharge capacity of the battery after one charge / discharge cycle (0.1C / 0.1C) was 185.37mAh / g. Further cycle tests were performed as follows: the battery was charged to 4.2V at a current of 0.5C and then discharged to 2.5V at a current of 0.5C to complete one cycle. The discharge capacity of the battery after one charge / discharge cycle (0.5C / 0.5C) was 156.185mAh / g (defined as 100% reversible capacity). The discharge capacity of the battery after 100 charge / discharge cycles (0.5C / 0.5C) was 138.23mAh / g (88.51% reversible capacity). The discharge capacity of the battery after 300 charge / discharge cycles (0.5C / 0.5C) was 114.65mAh / g (73.4% reversible capacity). After 500 charge / discharge cycles (0.5C / 0.5C) of the battery, the discharge capacity was 110.28mAh / g (70.61% reversible capacity).

[0035] Example 2 The organic-inorganic composite coating material of Example 1 was applied to a positive electrode plate and then dried to form an organic-inorganic composite film on the surface of the positive electrode plate. The positive electrode plate (containing the organic-inorganic composite film on its surface) and a silicon negative electrode plate were each cut to an appropriate size, and a separator was placed between the positive electrode plate and the silicon negative electrode plate. The organic-inorganic composite film was placed between the positive electrode plate and the separator. An electrolyte was injected into the space between the positive electrode plate and the silicon negative electrode plate, so that the separator was disposed in the electrolyte. The structure was left standing for one day to allow the electrolyte to diffuse and impregnate the positive and negative electrode plates. The structure was then charged to 4.2 V at a current of 0.1 C and then discharged to 2.5 V at a current of 0.1 C. This charge / discharge cycle was repeated three times to complete the formation process, resulting in a completed lithium battery.

[0036] The discharge capacity of the battery after one charge / discharge cycle (0.1C / 0.1C) was 183.60 mAh / g. Further cycle tests were performed as follows: the battery was charged to 4.2 V at a current of 0.5 C and then discharged to 2.5 V at a current of 0.5 C to complete one cycle. The reversible capacity of the battery after 100 charge / discharge cycles (0.5C / 0.5C) was 90.4%. The reversible capacity of the battery after 300 charge / discharge cycles (0.5C / 0.5C) was 81.41%. The reversible capacity of the battery after 500 charge / discharge cycles (0.5C / 0.5C) was 74.66%.

[0037] Example 3 The organic-inorganic composite coating material of Example 1 was applied to a separator and then dried to form an organic-inorganic composite film on the separator surface. A lithium iron phosphate positive electrode plate and a graphite negative electrode plate were each cut to an appropriate size, and a separator (with an organic-inorganic composite film on its surface) was placed between the positive and negative electrodes. The organic-inorganic composite film was then placed between the negative electrode plate and the separator. An electrolyte was injected into the space between the positive and negative electrodes, so that the separator was immersed in the electrolyte. The structure was left standing for one day to allow the electrolyte to diffuse and impregnate the positive and negative electrodes. The structure was then charged to 3.65 V at a current of 0.1 C and then discharged to 2.5 V at a current of 0.1 C. This charge / discharge cycle was repeated three times to complete the formation process, resulting in a completed lithium battery.

[0038] Example 4 1.5 g of lignocellulose and 13.5 g of montmorillonite clay (commercially available from Southern Clay, diameter less than 0.5 micrometers) were dispersed in 185 g of acetone. 35 g of PVDF powder (Kynar HSV900, commercially available from ARKEM) was added to the dispersion, and the mixture was stirred to completely disperse the mixture, yielding an organic-inorganic composite coating material.

[0039] The organic-inorganic composite coating material was applied to a semipermeable membrane and then dried to form an organic-inorganic composite film on the semipermeable membrane. The semipermeable membrane (containing the organic-inorganic composite film on its surface) was placed in the connecting tube between the left and right tubes. The left tube contained 500 ppm Mn 2+ The right tube contained a magenta-colored solution of ions and sodium oxalate, while the left tube contained deionized water. After 6 hours, the right tube was still clear (Mn 2+ The color of the solution in the left tube became lighter. 2+ The ions in the left tube were adsorbed. 2+ The ions were unable to permeate the organic-inorganic composite membrane. A semipermeable membrane (without the organic-inorganic composite membrane on its surface) was placed in the connecting tube between the left and right tubes. The left tube contained 500 ppm Mn 2+The right tube contained a magenta-colored solution of ions and sodium oxalate, while the left tube contained deionized water. After 6 hours, the right tube turned a pale magenta color (Mn 2+ ions were detected), and the color of the solution in the left tube became lighter. 2+ The ions were able to pass through the semipermeable membrane.

[0040] Example 5 1.5 g of lignocellulose modified with a chelating agent and 13.5 g of montmorillonite clay (commercially available from Southern Clay, diameter less than 0.5 micrometers) were dispersed in 185 g of acetone. 35 g of PVDF powder (Kynar HSV900, commercially available from ARKEM) was added to the dispersion and stirred to completely disperse the mixture, yielding an organic-inorganic composite coating material.

[0041] The organic-inorganic composite coating material was applied to a semipermeable membrane and then dried to form an organic-inorganic composite film on the semipermeable membrane. The semipermeable membrane (containing the organic-inorganic composite film on its surface) was placed in the connecting tube between the left and right tubes. The left tube contained 500 ppm Mn 2+ The right tube contained a magenta-colored solution of ions and sodium oxalate, while the left tube contained deionized water. After 12 hours, the right tube was still clear (Mn 2+ The color of the solution in the left tube became lighter. 2+ The ions in the left tube were adsorbed. 2+ The ions were unable to permeate the organic-inorganic composite membrane. A semipermeable membrane (without the organic-inorganic composite membrane on its surface) was placed in the connecting tube between the left and right tubes. The left tube contained 500 ppm Mn 2+ The right tube contained a magenta-colored solution of ions and sodium oxalate, while the left tube contained deionized water. After 12 hours, the right tube turned a pale magenta color (Mn 2+ ions were detected), and the color of the solution in the left tube became lighter. 2+ The ions were able to pass through the semipermeable membrane.

[0042] Example 6 1.5 g of lignocellulose modified with a chelating agent and 13.5 g of montmorillonite clay (commercially available from Southern Clay, diameter less than 0.5 micrometers) were dispersed in 185 g of acetone. 35 g of PVDF powder (Kynar HSV900, commercially available from ARKEM) was added to the dispersion and stirred to completely disperse the mixture, yielding an organic-inorganic composite coating material.

[0043] The organic-inorganic composite coating material was applied to a silicon negative electrode plate and then dried, forming an organic-inorganic composite film on the surface of the silicon negative electrode plate. The positive electrode plate and silicon negative electrode plate (containing the organic-inorganic composite film on their surfaces) were each cut to an appropriate size, and a separator was placed between the positive electrode plate and the silicon negative electrode plate. The organic-inorganic composite film was placed between the silicon negative electrode plate and the separator. Electrolyte was injected into the space between the positive electrode plate and the silicon negative electrode plate, so that the separator was immersed in the electrolyte. The structure was left to stand for one day to allow the electrolyte to diffuse and impregnate the positive and negative electrodes. The structure was then charged to 4.2 V at a current of 0.1 C and then discharged to 2.5 V at a current of 0.1 C. This charge / discharge cycle was repeated three times to complete the formation process, resulting in a completed lithium battery.

[0044] After one charge / discharge cycle (0.1C / 0.1C), the battery's discharge capacity was 187.3mAh / g. Further cycle testing was performed as follows: the battery was charged to 4.2V at a current of 0.5C, and then discharged to 2.5V at a current of 0.5C to complete one cycle. After one charge / discharge cycle (0.5C / 0.5C), the battery's discharge capacity was 163.53mAh / g.

[0045] Example 7 The organic-inorganic composite coating material of Example 6 was applied to a positive electrode plate and then dried to form an organic-inorganic composite film on the surface of the positive electrode plate. The positive electrode plate (containing the organic-inorganic composite film on its surface) and a silicon negative electrode plate were each cut to an appropriate size, and a separator was placed between the positive electrode plate and the silicon negative electrode plate. The organic-inorganic composite film was placed between the positive electrode plate and the separator. An electrolyte was injected into the space between the positive electrode plate and the silicon negative electrode plate, so that the separator was disposed in the electrolyte. The structure was left standing for one day to allow the electrolyte to diffuse and impregnate the positive and negative electrode plates. The structure was then charged to 4.2 V at a current of 0.1 C and then discharged to 2.5 V at a current of 0.1 C. This charge / discharge cycle was repeated three times to complete the formation process, resulting in a completed lithium battery.

[0046] The discharge capacity of the battery after one charge / discharge cycle (0.1C / 0.1C) was 184.02mAh / g. Further cycle tests were performed as follows: the battery was charged to 4.2V at a current of 0.5C and then discharged to 2.5V at a current of 0.5C to complete one cycle. The reversible capacity of the battery after 100 charge / discharge cycles (0.5C / 0.5C) was 99.98%. The reversible capacity of the battery after 300 charge / discharge cycles (0.5C / 0.5C) was 93.26%. The reversible capacity of the battery after 500 charge / discharge cycles (0.5C / 0.5C) was 88.31%.

[0047] Example 8 The organic-inorganic composite coating material of Example 6 was applied to a separator and then dried to form an organic-inorganic composite film on the separator surface. A lithium iron phosphate positive electrode plate and a graphite negative electrode plate were each cut to an appropriate size, and a separator (with an organic-inorganic composite film on its surface) was placed between the positive and negative electrodes. The organic-inorganic composite film was then placed between the negative electrode plate and the separator. An electrolyte was injected into the space between the positive and negative electrodes, so that the separator was immersed in the electrolyte. The structure was left standing for one day to allow the electrolyte to diffuse and impregnate the positive and negative electrodes. The structure was then charged to 3.65 V at a current of 0.1 C and then discharged to 2.5 V at a current of 0.1 C. This charge / discharge cycle was repeated three times to complete the formation process, resulting in a completed lithium battery.

[0048] After one charge / discharge cycle (0.1C / 0.1C), the charge capacity of the battery was 120.8mAh / g and the discharge capacity was 116.1mAh / g. The irreversible capacity of the battery in the first charge / discharge cycle was 3.9%, and the battery impedance was 260mohm.

[0049] Example 9 1.5 g of lignocellulose, 13.5 g of montmorillonite clay (commercially available from Southern Clay, diameter less than 0.5 micrometers), and 1.5 g of aluminum oxide powder were dispersed in 185 g of acetone. 35 g of PVDF powder (Kynar HSV900, commercially available from ARKEM) was added to the dispersion and stirred to completely disperse the mixture, yielding an organic-inorganic composite coating material.

[0050] The organic-inorganic composite coating material was applied to a silicon negative electrode plate and then dried, forming an organic-inorganic composite film on the surface of the silicon negative electrode plate. The positive electrode plate and silicon negative electrode plate (containing the organic-inorganic composite film on their surfaces) were each cut to an appropriate size, and a separator was placed between the positive electrode plate and the silicon negative electrode plate. The organic-inorganic composite film was placed between the silicon negative electrode plate and the separator. Electrolyte was injected into the space between the positive electrode plate and the silicon negative electrode plate, so that the separator was immersed in the electrolyte. The structure was left to stand for one day to allow the electrolyte to diffuse and impregnate the positive and negative electrodes. The structure was then charged to 4.2 V at a current of 0.1 C and then discharged to 2.5 V at a current of 0.1 C. This charge / discharge cycle was repeated three times to complete the formation process, resulting in a completed lithium battery.

[0051] After one charge / discharge cycle (0.1C / 0.1C), the battery's discharge capacity was 188.6 mAh / g. Further cycle testing was performed as follows: the battery was charged to 4.2 V at 0.5 C and then discharged to 2.5 V at 0.5 C to complete one cycle. After one charge / discharge cycle (0.5C / 0.5C), the battery's discharge capacity was 152.16 mAh / g (defined as 100% reversible capacity). After 100 charge / discharge cycles (0.5C / 0.5C), the battery's discharge capacity was 143.4 mAh / g (94.25% reversible capacity). After 300 charge / discharge cycles (0.5C / 0.5C), the battery's discharge capacity was 121.65 mAh / g (79.95% reversible capacity). After 500 charge / discharge (0.5C / 0.5C) cycles, the discharge capacity of the battery was 114.61 mAh / g (75.32% reversible capacity).

[0052] Comparative Example 2 The positive and negative silicon plates were cut to the appropriate size, and a separator was placed between them. An electrolyte was poured into the space between the positive and negative silicon plates, ensuring that the separator was immersed in the electrolyte. The structure was left standing for one day to allow the electrolyte to diffuse and permeate the positive and negative plates. The structure was then charged to 4.2 V at 0.1 C and then discharged to 2.5 V at 0.1 C. This charge / discharge cycle was repeated three times to complete the formation process, resulting in a completed lithium battery.

[0053] After one charge / discharge cycle (0.1C / 0.1C), the discharge capacity was 183.8mAh / g. Further cycle tests were performed as follows: the battery was charged to 4.2V at a current of 0.5C and then discharged to 2.5V at a current of 0.5C to complete one cycle. After one charge / discharge cycle (0.5C / 0.5C), the discharge capacity of the battery was 149mAh / g (defined as 100% reversible capacity). After 100 charge / discharge cycles (0.5C / 0.5C), the discharge capacity of the battery was 118mAh / g (79.6% reversible capacity). After 300 charge / discharge cycles (0.5C / 0.5C), the discharge capacity of the battery was 91.5mAh / g (61.3% reversible capacity). After 500 charge / discharge cycles (0.5C / 0.5C), the discharge capacity of the battery was 68.7mAh / g (46% reversible capacity).

[0054] Comparative Example 3 A lithium iron phosphate positive electrode plate and a graphite negative electrode plate were cut to the appropriate size, and a separator was placed between the positive and negative electrodes. An electrolyte was poured into the space between the positive and negative electrodes, so that the separator was immersed in the electrolyte. The structure was left standing for one day to allow the electrolyte to diffuse and impregnate the positive and negative electrodes. The structure was then charged to 3.65 V at a current of 0.1 C and then discharged to 2.5 V at a current of 0.1 C. This charge / discharge cycle was repeated three times to complete the formation process, resulting in a completed lithium battery.

[0055] After one charge / discharge cycle (0.1C / 0.1C), the charge capacity was 118.4mAh / g and the discharge capacity was 111.3mAh / g. The irreversible capacity of the battery in the first charge / discharge cycle was 6%, and the battery impedance was 280mohm.

[0056] Comparative Example 4 15 g of montmorillonite clay (commercially available from Southern Clay, diameter less than 0.5 micrometers) was dispersed in 185 g of acetone, and 35 g of PVDF powder (Kynar HSV900, commercially available from ARKEM) was added to the dispersion and stirred to completely disperse the mixture, yielding an organic-inorganic composite coating material.

[0057] The organic-inorganic composite coating material was applied to a silicon negative electrode plate and then dried, forming an organic-inorganic composite film on the surface of the silicon negative electrode plate. The positive electrode plate and silicon negative electrode plate (containing the organic-inorganic composite film on their surfaces) were each cut to an appropriate size, and a separator was placed between the positive electrode plate and the silicon negative electrode plate. The organic-inorganic composite film was placed between the silicon negative electrode plate and the separator. Electrolyte was injected into the space between the positive electrode plate and the silicon negative electrode plate, so that the separator was immersed in the electrolyte. The structure was left to stand for one day to allow the electrolyte to diffuse and impregnate the positive and negative electrodes. The structure was then charged to 4.2 V at a current of 0.1 C and then discharged to 2.5 V at a current of 0.1 C. This charge / discharge cycle was repeated three times to complete the formation process, resulting in a completed lithium battery.

[0058] After one charge / discharge cycle (0.1C / 0.1C), the battery's discharge capacity was 184.2mAh / g. Further cycle tests were performed as follows: the battery was charged to 4.2V at a current of 0.5C and then discharged to 2.5V at a current of 0.5C to complete one cycle. After one charge / discharge cycle (0.5C / 0.5C), the battery's discharge capacity was 142.4mAh / g (defined as 100% reversible capacity). After 100 charge / discharge cycles (0.5C / 0.5C), the battery's discharge capacity was 116.7mAh / g (81.93% reversible capacity). After 300 charge / discharge cycles (0.5C / 0.5C), the battery's discharge capacity was 92.95mAh / g (65.3% reversible capacity). After 500 charge / discharge cycles (0.5C / 0.5C), the discharge capacity of the battery was 73.2 mAh / g (reversible capacity 51.43%).

[0059] Comparative Example 5 40 g of montmorillonite clay (commercially available from Southern Clay, diameter less than 0.5 micrometers) was dispersed in 160 g of acetone. 10 g of PVDF powder (Kynar HSV900, commercially available from ARKEM) was added to the dispersion, and the mixture was stirred to completely disperse the powder, yielding an organic-inorganic composite coating material.

[0060] The organic-inorganic composite coating material was applied to a silicon negative electrode plate and then dried, forming an organic-inorganic composite film on the surface of the silicon negative electrode plate. The positive electrode plate and silicon negative electrode plate (containing the organic-inorganic composite film on their surfaces) were each cut to an appropriate size, and a separator was placed between the positive electrode plate and the silicon negative electrode plate. The organic-inorganic composite film was placed between the silicon negative electrode plate and the separator. Electrolyte was injected into the space between the positive electrode plate and the silicon negative electrode plate, so that the separator was immersed in the electrolyte. The structure was left to stand for one day to allow the electrolyte to diffuse and impregnate the positive and negative electrodes. The structure was then charged to 4.2 V at a current of 0.1 C and then discharged to 2.5 V at a current of 0.1 C. This charge / discharge cycle was repeated three times to complete the formation process, resulting in a completed lithium battery.

[0061] After one charge / discharge cycle (0.1C / 0.1C), the battery's discharge capacity was 180mAh / g. Further cycle tests were performed as follows: the battery was charged to 4.2V at a current of 0.5C and then discharged to 2.5V at a current of 0.5C to complete one cycle. After one charge / discharge cycle (0.5C / 0.5C), the battery's discharge capacity was 99.5mAh / g (defined as 100% reversible capacity). After 100 charge / discharge cycles (0.5C / 0.5C), the battery's discharge capacity was 88.5mAh / g (94.25% reversible capacity). After 300 charge / discharge cycles (0.5C / 0.5C), the battery's discharge capacity was 79.8mAh / g (80.1% reversible capacity). After 500 charge / discharge cycles (0.5C / 0.5C), the discharge capacity of the battery was 84.6 mAh / g (reversible capacity was 85%).

[0062] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed methods and materials. It is intended that the specification and examples be considered as exemplary, with the true scope of the disclosure being indicated by the following claims and their equivalents.

Claims

1. 100 parts by weight of clay, 3 to 35 parts by weight of lignocellulose; 25 to 270 parts by weight of a first binder; An organic-inorganic composite film for a lithium battery comprising a silicon negative electrode plate comprising: The organic-inorganic composite membrane, wherein the lignocellulose is modified with a chelating agent, and the weight ratio of the lignocellulose to the chelating agent is 100:0.1 to 100:

20.

2. The organic-inorganic composite film of claim 1 , wherein the clay comprises a montmorillonite clay, a vermiculite clay, or a combination thereof.

3. 2. The organic-inorganic composite film according to claim 1, wherein the clay has a diameter of 1 micrometer or less.

4. 2. The organic-inorganic composite film according to claim 1, wherein the first binder comprises polyacrylic acid, polyacrylonitrile, polyethylene carbonate, polyacrylamide, polyethylene glycol, polysiloxane, polyamide, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyvinylpyrrolidone, or a combination thereof.

5. 2. The organic-inorganic composite film according to claim 1, wherein the chelating agent includes N,N-bis(5-pyridoxal phosphate)-ethylenediamine-N,N'-diacetic acid, N,N'-bis(3-hydroxy-2-methyl-5-phosphonylmethyl)-4-pyridylmethyl)ethylenediamine-N,N'-diacetic acid (DPDP), diethylenetriaminepentaacetic acid (DTPA), cyclohexanediaminetetraacetic acid (DCTA), N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine (EDTP), 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), ethylenediaminetetraacetic acid (EDTA), 1-oxa-4,7,10-triazacyclododecanetriacetic acid (DOXA), 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid trisodium salt (DO3A), or a combination thereof.

6. The organic-inorganic composite film according to claim 1, further comprising 0.1 to 15 parts by weight of an oxide nanopowder.

7. The organic-inorganic composite film according to claim 6 , wherein the oxide nanopowder comprises aluminum oxide, silicon oxide, boehmite, titanium oxide, magnesium oxide, or a combination thereof.

8. The organic-inorganic composite film according to claim 1 , wherein the diameter of the oxide nanopowder is 1 nm to 200 nm.

9. 2. The organic-inorganic composite film according to claim 1, wherein the thickness of the organic-inorganic composite film is from 0.1 micrometers to 10 micrometers.

10. A positive electrode plate; A silicon negative electrode plate; an electrolyte disposed between the positive electrode plate and the negative electrode plate; a separator disposed in the electrolyte; The organic-inorganic composite membrane according to claim 1 , which is disposed on a surface of the positive electrode plate, a surface of the negative electrode plate, a surface of the separator, or a combination thereof; Contains lithium batteries.