Solid-state battery binder, preparation method and application thereof, composite electrolyte film, and solid-state battery composite cathode

Abstract

The present application relates to the technical field of solid-state battery, and discloses a solid-state battery binder, a preparation method and application thereof, a composite electrolyte film and a solid-state battery composite positive electrode, wherein the solid-state battery binder is a product obtained by grafting a group represented by formula (I) onto a non-polar unsaturated rubber; the grafting rate of the group represented by formula (I) is 5-10%; formula (I) is -S-R-OH, wherein R is selected from C1-C6 alkylene, phenylene and tolylene; and the non-polar unsaturated rubber includes at least one of styrene-butadiene-styrene block copolymer, butadiene rubber, styrene-butadiene rubber, isoprene rubber and chloroprene rubber. The battery binder provided by the present application has strong adhesion and can be dissolved in a medium-polar solvent or a weak-polar solvent, and the solid-state battery prepared by using the binder has more excellent electrochemical performance.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, specifically to a solid-state battery binder and its preparation method and application, a composite electrolyte membrane, and a solid-state battery composite cathode. Background Technology

[0002] All-solid-state batteries, which use solid electrolytes instead of liquid electrolytes and separators, offer better safety performance and higher energy density, making them a very promising new type of battery. Among various solid electrolytes, sulfide-based solid electrolytes have become a research hotspot due to their high room-temperature ionic conductivity, even surpassing that of liquid electrolytes. However, sulfide-based all-solid-state batteries still face the challenge of combining solvents and binders in wet manufacturing processes. In polar solvents, the crystal structure of sulfide electrolytes is disrupted, leading to a decrease in ionic conductivity.

[0003] In commercially available liquid lithium-ion batteries, conventional polyvinylidene fluoride (PVDF) has become the primary binder due to its mechanical, chemical, and electrochemical stability. Currently, existing PVDF-based binder systems are only soluble in polar solvents, thus failing to meet the requirements for sulfide-based solid-state battery applications. Sulfide wet-process slurries are primarily developed based on non-polar or weakly polar solvents. Due to the principle of "like dissolves like," the limitation in solvent selection also restricts binder systems, typically resulting in non-polar or low-polarity polymer systems. However, these binders exhibit relatively weak adhesion to sulfide electrolyte particles, ternary cathode active materials, and current collectors, leading to poor processability and consequently, poor battery cycle performance.

[0004] Therefore, developing novel binders is crucial for achieving high-performance sulfide-based all-solid-state batteries. Summary of the Invention

[0005] The purpose of this invention is to provide a battery binder with strong adhesion that is soluble in moderately polar or weakly polar solvents.

[0006] To achieve the above objectives, a first aspect of the present invention provides a solid-state battery binder, which is a product obtained by grafting a group of formula (I) onto a nonpolar unsaturated rubber; the grafting rate of the group of formula (I) is 5-10%.

[0007] -SR-OH formula (I)

[0008] Wherein, R is selected from C1-C6 alkylene, phenylene, and tolylide;

[0009] The nonpolar unsaturated rubber includes at least one of styrene-butadiene-styrene block copolymer, butadiene rubber, styrene-butadiene rubber, isoprene rubber, and chloroprene rubber.

[0010] A second aspect of the present invention provides a method for preparing the solid-state battery binder described in the first aspect, the method comprising:

[0011] In the presence of benzene-based solvents and photoinitiators, a nonpolar unsaturated rubber and the compound shown in formula (II) are grafted to obtain a solid battery binder; the molar ratio of the compound shown in formula (II) to the carbon-carbon double bonds contained in the nonpolar unsaturated rubber is 0.5-5:1.

[0012] HS-R-OH formula (II)

[0013] R is selected from C1-C6 alkylene, phenylene, and tolyl groups.

[0014] A third aspect of the present invention provides the application of the solid-state battery binder described in the first aspect in a sulfide-based all-solid-state battery.

[0015] A fourth aspect of the present invention provides a composite electrolyte membrane containing a sulfide electrolyte and a solid-state battery binder; based on the total mass of the composite electrolyte membrane, the content of the sulfide electrolyte is 80-99 wt%, and the content of the solid-state battery binder is 1-20 wt%; the solid-state battery binder is the solid-state battery binder described in the first aspect above.

[0016] A fifth aspect of the present invention provides a solid-state battery composite cathode, the solid-state battery composite cathode comprising: an active material, a conductive agent, a sulfide electrolyte, and a solid-state battery binder; wherein the solid-state battery binder is the solid-state battery binder described in the first aspect above.

[0017] This invention introduces hydroxyl groups into nonpolar unsaturated rubber, which significantly improves adhesion while ensuring solubility in moderately and weakly polar solvents.

[0018] The composite electrolyte membrane prepared using this binder has better mechanical properties and flexibility, as well as higher room temperature ionic conductivity.

[0019] The composite cathode prepared using this binder forms more hydrogen bonds with the surface of the coated nickel-cobalt-manganese ternary cathode material, enhancing adhesion between the composite cathode and the active material. Even with very low binder content (<2%), no powder shedding occurs, and the coating is less prone to breakage and detachment when the electrode is bent, thus optimizing processing performance. Furthermore, the hydrogen bonding between the solid-state battery binder and the nickel-cobalt-manganese ternary active material provided by this invention can suppress the volume expansion of nickel-cobalt-manganese particles, thereby reducing particle breakage and improving the cycle performance of the nickel-cobalt-manganese cathode.

[0020] The adhesive preparation method provided by this invention is simple and effective, with mild reaction conditions. The desired product can be obtained in just one step with high yield, which is of great significance for industrial production. Attached Figure Description

[0021] Figure 1 The solid-state battery binder structure fragment of this invention is a bonded-line type;

[0022] Figure 2 These are the infrared spectra of the adhesives in the various embodiments and comparative examples of this invention;

[0023] Figure 3 These are the 1H NMR spectra of SBS binder and SBS-OH binder;

[0024] Figure 4 These are the 1H NMR spectra of BR binder and BR-OH binder;

[0025] Figure 5 These are the 1H NMR spectra of SBR binder and SBR-OH binder;

[0026] Figure 6 This is a graph showing the cycle performance of batteries assembled in Application Example 1-B and Comparative Example 1-B of the present invention at 0.1C current and 25°C.

[0027] Figure 7 These are impedance diagrams of batteries assembled in Application Example 1-B and Comparative Example 1-B of the present invention after 0.1C current, 25°C, and 100 cycles.

[0028] Figure 8 These are impedance diagrams of the composite electrolyte membranes corresponding to various application embodiments and comparative examples of the present invention at 25°C.

[0029] Figure 9 This is a graph showing the cycle performance of the battery assembled using Comparative Example 5-B at 0.1C current and 25°C.

[0030] Figure 10 Impedance diagram of the battery assembled using Comparative Example 5-B after 100 cycles at 0.1C current and 25°C;

[0031] Figure 11 Impedance diagram of the composite electrolyte membrane corresponding to Comparative Example 5-A at 25°C. Detailed Implementation

[0032] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0033] The "C1-C6 alkylene" mentioned in this invention refers to an alkylene with a total number of carbon atoms of 1-6, such as -CH2-, -CH2CH2-, -CH2CH(CH3)CH2-, including straight-chain alkylene and branched-chain alkylene.

[0034] The "phenylene" mentioned in this invention refers to the group formed by removing two H atoms from any position on the benzene ring.

[0035] The "methylenetoluene" mentioned in this invention refers to the group formed by removing two H atoms from any position on the benzene ring of toluene.

[0036] It should be noted that, in all aspects of the present invention, the same components or terms in each aspect are described only once in one aspect and not repeatedly, and those skilled in the art should not understand this as a limitation of the present invention.

[0037] As previously stated, a first aspect of the present invention provides a solid-state battery binder, which is a product obtained by grafting a group of formula (I) onto a nonpolar unsaturated rubber; the grafting rate of the group of formula (I) is 5-10%.

[0038] -SR-OH formula (I)

[0039] R is selected from C1-C6 alkylene, phenylene, and tolyl groups.

[0040] The nonpolar unsaturated rubber includes at least one of styrene-butadiene-styrene block copolymer (SBS), butadiene rubber (BR), styrene-butadiene rubber (SBR), isoprene rubber (IR), and chloroprene rubber (CR).

[0041] Preferably, in formula (I), R is selected from -CH2-, -CH2CH2-, and -CH2CH2CH2-.

[0042] In a preferred embodiment, the weight-average molecular weight of the nonpolar unsaturated rubber is 50,000 to 300,000, and more preferably 120,000 to 200,000.

[0043] In some embodiments, the solid-state battery binder is a product obtained by grafting -S-CH2CH2-OH onto a styrene-butadiene-styrene block copolymer. Preferably, the weight-average molecular weight of the styrene-butadiene-styrene block copolymer is 100,000-200,000. Preferably, the styrene structural units in the styrene-butadiene-styrene block copolymer contain 25-35 wt%.

[0044] In some embodiments, the solid-state battery binder is a product obtained by grafting -S-CH2CH2-OH onto butadiene rubber. Preferably, the butadiene rubber has a weight-average molecular weight of 200,000 to 300,000.

[0045] In some embodiments, the solid-state battery binder is a product obtained by grafting -S-CH2CH2-OH onto styrene-butadiene rubber. Preferably, the weight-average molecular weight of the styrene-butadiene rubber is 50,000-80,000. Preferably, the styrene structural units in the styrene-butadiene rubber contain 20-30 wt%.

[0046] According to a preferred embodiment 1, the solid-state battery binder is a product obtained by grafting -S-CH2CH2-OH onto a styrene-butadiene-styrene block copolymer, and the molecular formula of the solid-state battery binder is (C8H8). m (CH2CH=CHCH2) n (C8H8) k (C6H 11 SOH) h [CH2CH(CH=CH2)] j , where m+k takes values ​​of 430-450, and n+h+j takes values ​​of 2500-2700.

[0047] It should be noted that the molecular formulas of solid-state battery binders include (C8H8), (CH2CH=CHCH2), (C8H8), and (C6H... 11 SOH and [CH2CH(CH=CH2)] refer to the structural units contained in the solid-state battery binder. The aforementioned arrangement of these structural units does not indicate the order of their connection relationships. m, n, k, h, and j represent the number of repeating units in each structural unit. This invention provides, exemplarily, a partial structural fragment of a solid-state battery binder, specifically as follows: Figure 1 As shown in the left figure.

[0048] According to a preferred embodiment 2, the solid-state battery binder is a product obtained by grafting -S-CH2CH2-OH onto butadiene rubber, and the molecular formula of the solid-state battery binder is (CH2CH=CHCH2). m (C6H 11 SOH) n , where m+n takes values ​​from 6100 to 6300.

[0049] It should be noted that the molecular formula of the solid-state battery binder contains (CH2CH=CHCH2) and (C6H 11 SOH refers to the structural units contained in the solid-state battery binder. The aforementioned arrangement of these structural units does not indicate the order of their connection relationships. m and n represent the number of repeating units in each structural unit. This invention provides, exemplarily, a partial structural fragment of a solid-state battery binder, specifically as follows: Figure 1 The middle image is shown in the figure.

[0050] According to a preferred embodiment 3, the solid-state battery binder is a product obtained by grafting -S-CH2CH2-OH onto styrene-butadiene rubber, and the molecular formula of the solid-state battery binder is (C8H8). m (CH2CH=CHCH2) n (C6H 11 SOH) k [CH2CH(CH=CH2)] h , where m takes values ​​of 100-150 and n+k+h takes values ​​of 900-1000.

[0051] It should be noted that the molecular formula of the solid-state battery binder includes (C8H8), (CH2CH=CHCH2), and (C6H... 11 SOH and [CH2CH(CH=CH2)] refer to the structural units contained in the solid-state battery binder. The aforementioned arrangement of these structural units does not indicate the order of their connection relationships. m, n, k, and h represent the number of repeating units in each structural unit. This invention provides, exemplarily, a partial structural fragment of a solid-state battery binder, specifically as follows: Figure 1 As shown in the right figure.

[0052] As previously described, a second aspect of the present invention provides a method for preparing the solid-state battery binder described in the first aspect, the method comprising:

[0053] In the presence of benzene-based solvents and photoinitiators, a nonpolar unsaturated rubber and the compound shown in formula (II) are grafted to obtain a solid battery binder; the molar ratio of the compound shown in formula (II) to the carbon-carbon double bonds contained in the nonpolar unsaturated rubber is 0.5-5:1.

[0054] HS-R-OH formula (II)

[0055] R is selected from C1-C6 alkylene, phenylene, and tolyl groups.

[0056] Preferably, the compound represented by formula (II) includes at least one of mercaptoethanol, 3-mercapto-1-propanol, 4-mercapto-1-butanol, 3-mercapto-2-methylpentanol, 6-mercaptohex-1-ol, p-hydroxythiophenol, 2-hydroxythiophenol, 3-hydroxythiophenol, and 4-hydroxy-3-methylthiophenol; mercaptoethanol is particularly preferred.

[0057] In a preferred embodiment, the molar ratio of the compound represented by formula (II) to the carbon-carbon double bonds contained in the nonpolar unsaturated rubber is 1-2.5:1.

[0058] In some embodiments of the present invention, the photoinitiator includes at least one of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-2-phenylethyl ketone, ethyl 2,4,6-trimethylbenzoylphosphonate, and 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone; particularly preferably 1-hydroxycyclohexylphenyl ketone.

[0059] In some embodiments of the present invention, the benzene-based solvent includes at least one of benzene, toluene, o-xylene, m-xylene, p-xylene, and anisole.

[0060] Preferably, the molar ratio of the photoinitiator to the carbon-carbon double bonds contained in the nonpolar unsaturated rubber is 0.01-0.05:1, more preferably 0.01-0.02:1.

[0061] In a preferred embodiment, the grafting reaction is carried out under ultraviolet light irradiation conditions, which include: a temperature of 10-50°C, preferably 20-35°C; and a time of 10 min to 5 h, preferably 1-2 h.

[0062] In a preferred embodiment, the ultraviolet light irradiation wavelength for the grafting reaction is 365-380 nm.

[0063] According to a preferred embodiment of the present invention, the method for preparing the solid-state battery binder includes:

[0064] S1: In the presence of a benzene-based solvent, a nonpolar unsaturated rubber and the compound shown in formula (II) are first mixed to obtain an intermediate mixture;

[0065] S2: In the presence of a photoinitiator and under ultraviolet light irradiation, the intermediate mixture is subjected to the grafting reaction to obtain the solid battery binder.

[0066] The present invention does not impose any particular restrictions on the conditions of the first mixing, as long as the nonpolar unsaturated rubber can be dissolved in the benzene solvent and the compound represented by formula (II) is uniformly dispersed in the mixing system. The present invention will not elaborate further here, and those skilled in the art should not understand it as a limitation of the present invention.

[0067] The method described in this invention may further include post-processing techniques known in the art, such as extraction, washing, and drying. For example, the product in the mixed system after the grafting reaction is completed is extracted with methanol, then redissolved in a benzene-based solvent, and repeated three times to wash away any unreacted small molecules. The resulting product is then placed in a freeze dryer and dried for 24 hours to remove the solvent, yielding the solid-state battery binder. This invention will not be described in detail here, and those skilled in the art should not construe it as a limitation of the invention.

[0068] As previously stated, a third aspect of the present invention provides the application of the solid-state battery binder described in the first aspect in a sulfide-based all-solid-state battery.

[0069] In a preferred embodiment, the sulfide-based all-solid-state battery is a sulfide-based all-solid-state lithium-ion battery.

[0070] As previously stated, a fourth aspect of the present invention provides a composite electrolyte membrane containing a sulfide electrolyte and a solid-state battery binder; based on the total mass of the composite electrolyte membrane, the content of the sulfide electrolyte is 80-99 wt%, and the content of the solid-state battery binder is 1-20 wt%; the solid-state battery binder is the solid-state battery binder described in the first aspect above.

[0071] In a preferred embodiment, the thickness of the composite electrolyte membrane is 20-40 μm.

[0072] According to a preferred embodiment of the present invention, the sulfide electrolyte comprises Li7P2S8I, αLi2S-(100-α)P2S5, and Li 6-X5-X6 P 1-X6 T X6 S 5-X5-X7 G X7 Z X5+1 At least one of them;

[0073] Wherein, 70≤α≤80, 0≤X5<1, 0≤X6<1, 0≤X7<1; T is selected from at least one of Ge, Si, Sn, Sb, and As; G is O and / or Se; Z is selected from at least one of Cl, Br, and I.

[0074] According to a preferred embodiment of the present invention, the method for preparing the composite electrolyte membrane includes:

[0075] In the presence of organic solvent I, the sulfide electrolyte and solid battery binder are dispersed to obtain a dispersion; then the dispersion is sequentially cast and dried to obtain the composite electrolyte membrane.

[0076] In a preferred embodiment, the organic solvent I is selected from at least one of toluene, p-xylene, and anisole.

[0077] In a preferred embodiment, the amount of the solid-state battery binder is 0.5-5g relative to 100mL of the organic solvent I.

[0078] In a preferred embodiment, the method further includes: hot-pressing the product obtained after drying to obtain the composite electrolyte membrane.

[0079] The present invention does not impose any particular requirements on the methods of dispersion treatment, casting, drying and hot pressing, and those skilled in the art can use methods known in the art.

[0080] As previously described, a fifth aspect of the present invention provides a solid-state battery composite cathode, which includes: an active material, a conductive agent, a sulfide electrolyte, and a solid-state battery binder; wherein the solid-state battery binder is the solid-state battery binder described in the first aspect above.

[0081] In this invention, the sulfide electrolyte preferably used in the solid-state battery composite cathode has the same definition as the fourth aspect mentioned above, and will not be repeated here.

[0082] In a preferred embodiment, the active substance comprises at least one of the compounds shown in formula (1), formula (2), formula (3), formula (4), and formula (5);

[0083] Formula (1): LiCoO2;

[0084] Equation (2): LiNi x1 Mn y1 Co 1-x1-y1 O2;

[0085] Formula (3): LiNi 1-x2-y2 Co x2 Al y2 O2;

[0086] Equation (4): LiNi x3 Mn 1-x3 O2;

[0087] Equation (5): Li 1+x4 EO2;

[0088] Among them, x1, x2, x3, x4, y1, and y2 are each independently selected from any value between 0 and 1;

[0089] E is selected from any one of Mn, Ni, Co, and Al.

[0090] The “any value from 0 to 1” mentioned in this invention includes endpoint values ​​of 0 and 1.

[0091] In a preferred embodiment, the conductive agent is selected from at least one of conductive carbon black Super-P, acetylene black, conductive carbon black Super C65, carbon fiber (VGCF), multi-walled carbon nanotubes (MWCNT), single-walled carbon nanotubes (SWCNT), and graphene.

[0092] In a preferred embodiment, the solid-state battery composite cathode further includes a cathode current collector.

[0093] According to a preferred embodiment of the present invention, the method for preparing the solid-state battery composite cathode includes:

[0094] SS1: In the presence of organic solvent II, the active material, conductive agent, sulfide electrolyte and solid battery binder are contact-mixed to obtain the positive electrode slurry;

[0095] SS2: The positive electrode slurry is coated onto the surface of the positive electrode current collector, and then dried and rolled to obtain the solid-state battery composite positive electrode.

[0096] In a preferred embodiment, the mass ratio of the active material, the sulfide electrolyte, the conductive agent, and the solid battery binder is (75-95):(5-25):(0.5-5):(0.5-3).

[0097] Preferably, the organic solvent II is a benzene-based solvent, and the organic solvent II is selected from at least one of benzene, toluene, o-xylene, m-xylene, p-xylene, and anisole.

[0098] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, all raw materials are commercially available. Unless otherwise specified, room temperature refers to 25±2℃.

[0099] The anhydrous xylene used in the following examples is a mixture of commercially available o-xylene, m-xylene, and p-xylene.

[0100] Styrene-butadiene-styrene block copolymer (SBS): weight average molecular weight Mw = 150,000, styrene structural unit content is 30wt%.

[0101] Butadiene rubber (BR): weight average molecular weight Mw = 250,000.

[0102] Styrene-butadiene rubber (SBR): weight average molecular weight Mw = 50,000, styrene structural unit content is 25wt%.

[0103] The grafting rate test or calculation method involved in the following examples is as follows: The intensity of each peak in the 1H NMR spectrum is related to the number of hydrogen atoms in the molecule. The integral represents the area ratio of different peaks, thus reflecting the number of hydrogen atoms. The grafting rate is calculated by corresponding hydrogen atoms at different positions in the molecular structure.

[0104] Example 1

[0105] Preparation of solid-state battery binder SBS-OH

[0106] (1) Weigh 1g of SBS and add it to the reaction vessel, then add 30 mL of anhydrous xylene and stir for 1 hour to completely dissolve and disperse evenly until there is no precipitate.

[0107] (2) Add 30 mg of 1-hydroxycyclohexylphenyl ketone and 1 mL of mercaptoethanol to the reaction solution, stir for 2 h, and after stirring evenly, carry out the grafting reaction for 1 h under ultraviolet light irradiation. The reaction temperature is 25℃ and the ultraviolet light wavelength is 380 nm.

[0108] (3) After the reaction is complete, the reaction solution is poured into methanol, and the precipitate is dissolved in xylene. This process is repeated three times. The precipitate is then placed in a freeze dryer and dried for 24 hours to obtain solid battery binder (SBS-OH).

[0109] The molecular formula of SBS-OH is (C8H8). m (CH2CH=CHCH2) n (C8H8) k (C6H 11 SOH) h [CH2CH(CH=CH2)] j Where m+k≈440, n+h+j≈2600; the grafting rate is 8.3%.

[0110] Figure 1 The left image shows a partial structural fragment of SBS-OH. Infrared spectrum as shown... Figure 2 As shown in (a), the characteristic is: 3300cm -1 The -OH peak near the location, the 1H NMR spectrum is as follows Figure 3 As shown, the characteristic features are two sets of peaks at 2.7 and 3.7 ppm.

[0111] Application Example 1-A

[0112] Application of binder SBS-OH in composite electrolyte membrane in Example 1

[0113] Dissolve 1 g of SBS-OH binder in 300 mL of p-xylene solution, and add 99 g of Li... 5.5 PS 4.5 Cl 0.75 Br 0.75 (LPSCB) sulfide electrolyte is added to the solution and stirred to disperse the sulfide electrolyte evenly. Finally, it is cast onto a polytetrafluoroethylene plate and the solvent is evaporated to obtain an LPSCB-(SBS-OH) composite electrolyte membrane.

[0114] Application of Comparative Example 1-A

[0115] Application of SBS binder in composite electrolyte membranes

[0116] Dissolve 1 g of SBS binder in 300 mL of p-xylene solution, and add 99 g of Li 5.5 PS 4.5 Cl 0.75 Br 0.75 The sulfide electrolyte is added to the solution and stirred to disperse it evenly. Finally, it is cast onto a polytetrafluoroethylene plate and the solvent is evaporated to obtain the LPSCB-SBS composite electrolyte membrane.

[0117] Application Example 1-B

[0118] Application of binder SBS-OH in all-solid-state lithium-ion batteries in Example 1

[0119] According to LiNi 0.83 Co 0.11 Mn 0.06 The pulp was prepared using a mass ratio of O2:LPSCB:Super P:SBS-OH of 80:20:2:1. First, the SBS-OH binder was dissolved in anhydrous toluene, and then LiNi... 0.83 Co 0.11 Mn 0.06 O2, LPSCB sulfide electrolyte, and carbon fiber VGCF were added to the above mixture and stirred at 800 rpm for 4 hours to obtain a uniform slurry. The slurry was then cast onto aluminum foil and subsequently dried in a vacuum oven at 70°C for 12 hours to obtain a composite positive electrode sheet.

[0120] The dried positive electrode sheet was cut into 10 mm diameter positive electrode sheets on a manual slicing machine. The composite electrolyte membrane in Example 1-A was used as the intermediate electrolyte membrane layer, and lithium indium alloy was selected as the negative electrode. The battery was assembled and cycled in a glove box.

[0121] Application of Comparative Example 1-B

[0122] Application of SBS binder in all-solid-state lithium-ion batteries

[0123] According to LiNi 0.83 Co 0.11 Mn 0.06 The O2:LPSCB:Super P:SBS mass ratio was 80:20:2:1 for pulping. First, the SBS binder was dissolved in anhydrous toluene, then LiNi... 0.83 Co 0.11 Mn 0.06 O2, LPSCB sulfide solid electrolyte, and carbon fiber VGCF were added to the above mixture and stirred at 800 rpm for 4 hours to obtain a uniform slurry. The slurry was then cast onto aluminum foil and subsequently dried in a vacuum oven at 70°C for 12 hours to obtain a composite positive electrode sheet.

[0124] The dried electrode sheets were cut into positive electrode sheets with a diameter of 10 mm on a manual slicing machine. The composite electrolyte membrane in Application Example 1-A was selected as the intermediate electrolyte membrane layer, and lithium indium alloy was selected as the negative electrode. The batteries were assembled and cycled in a glove box.

[0125] Example 2

[0126] Preparation of solid-state battery binder BR-OH

[0127] (1) Weigh 2g of BR and add it to the reaction vessel, then add 50 mL of anhydrous xylene and stir for 30 min to completely dissolve and disperse evenly until there is no precipitate.

[0128] (2) Add 210 mg of phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide and 5.5 mL of mercaptoethanol to the reaction solution, stir for 3 h, and after stirring evenly, carry out the grafting reaction under ultraviolet light irradiation for 2 h. The reaction temperature is 25℃ and the ultraviolet light wavelength is 380 nm.

[0129] (3) After the reaction is complete, pour the reaction solution into methanol, dissolve the precipitate in xylene, repeat three times, and then place the precipitate in a freeze dryer to dry for 24 h to obtain modified hydroxylated butadiene rubber (BR-OH).

[0130] The molecular formula of BR-OH is (CH2CH=CHCH2). m (C6H 11 SOH) n Where m+n≈6240; the grafting rate is 6.2%.

[0131] Figure 1 The middle image shows a partial structural fragment of BR-OH. The infrared spectrum is as follows: Figure 2 As shown in (b), the feature is: 3300cm -1 The -OH peak near the location, the 1H NMR spectrum is as follows Figure 4As shown, the characteristic features are two sets of peaks at 2.7 and 3.7 ppm.

[0132] Application Example 2-A

[0133] Application of binder BR-OH in composite electrolyte membrane in Example 2

[0134] Dissolve 1 g of BR-OH binder in 300 mL of p-xylene solution, and add 99 g of Li 5.5 PS 4.5 Cl 1.5 The sulfide electrolyte was added to the solution, stirred to ensure uniform dispersion, and finally cast onto a polytetrafluoroethylene plate to evaporate the solvent, yielding Li. 5.5 PS 4.5 Cl 1.5 - (BR-OH) composite electrolyte membrane.

[0135] Application of Comparative Example 2-A

[0136] Application of binder BR in composite electrolyte membranes

[0137] Dissolve 1 g of BR binder in 300 mL of p-xylene solution, and add 99 g of Li 5.5 PS 4.5 Cl 1.5 The sulfide electrolyte was added to the solution, stirred to ensure uniform dispersion, and finally cast onto a polytetrafluoroethylene plate to evaporate the solvent, yielding Li. 5.5 PS 4.5 Cl 1.5 -BR composite electrolyte membrane.

[0138] Application Example 2-B

[0139] Application of binder BR-OH in all-solid-state lithium-ion batteries in Example 2

[0140] According to LiNi 0.9 Co 0.06 Mn 0.04 The pulp was prepared using a mass ratio of O2:LPSC:MWCNT:BR-OH of 75:25:1.5:1. First, the BR-OH binder was dissolved in anhydrous toluene, and then LiNi... 0.9 Co 0.06 Mn 0.04 O2, Li 5.5 PS 4.5 Cl 1.5 Multi-walled carbon nanotubes (MWCNTs) were added to the above mixture and stirred at 500 rpm for 4 hours to obtain a uniform slurry. The slurry was then cast onto aluminum foil and subsequently dried in a vacuum oven at 70°C for 12 hours to obtain a composite positive electrode sheet.

[0141] The dried positive electrode sheet was cut into 10mm diameter positive electrode sheets on a manual slicing machine. The electrolyte membrane in Application Example 2-A was selected as the intermediate electrolyte membrane layer, and lithium indium alloy was selected as the negative electrode. The battery was assembled and cycled in a glove box.

[0142] Application of Comparative Example 2-B

[0143] Application of binder BR in all-solid-state lithium-ion batteries

[0144] According to LiNi 0.9 Co 0.06 Mn 0.04 The O2:LPSCB:MWCNT:BR mass ratio was 75:25:1.5:1 for pulp preparation. First, the BR binder was dissolved in anhydrous toluene, then LiNi... 0.9 Co 0.06 Mn 0.04 O2, Li 5.5 PS 4.5 Cl 1.5 Sulfide solid electrolyte and multi-walled carbon nanotubes (MWCNTs) were added to the above mixture and stirred at 500 rpm for 4 hours to obtain a uniform slurry. The slurry was then cast onto aluminum foil and subsequently dried in a vacuum oven at 70°C for 12 hours to obtain a composite positive electrode sheet.

[0145] The dried electrode sheets were cut into positive electrode sheets with a diameter of 10 mm on a manual slicing machine. The electrolyte membrane in Application Example 2-A was selected as the intermediate electrolyte membrane layer, and lithium indium alloy was selected as the negative electrode. The batteries were assembled and cycled in a glove box.

[0146] Example 3

[0147] Preparation of solid-state battery binder SBR-OH

[0148] (1) Weigh 2g of SBR and add it to the reaction vessel, then add 100 mL of anhydrous xylene and stir for 1 hour to completely dissolve and disperse evenly until there is no precipitate.

[0149] (2) Add 100 mg of 2,2-dimethoxy-2-phenylethyl ketone and 3.6 mL of mercaptoethanol to the reaction solution, stir for 1 h, and after stirring evenly, carry out the grafting reaction for 1 h under ultraviolet light irradiation. The reaction temperature is 25℃ and the ultraviolet light wavelength is 380 nm.

[0150] (3) After the reaction is complete, pour the reaction solution into methanol, dissolve the precipitate in xylene, repeat three times, and then place the precipitate in a freeze dryer to dry for 24 h to obtain modified hydroxylated styrene-butadiene rubber (SBR-OH).

[0151] The molecular formula of SBR-OH is (C8H8). m (CH2CH=CHCH2) n (C6H 11 SOH) k [CH2CH(CH=CH2)] h Where m≈120, n+k+h≈940; the grafting rate is 6.9%.

[0152] Figure 1 The right figure shows a partial structural fragment of SBR-OH. Infrared spectrum as shown... Figure 2 As shown in (c), the feature is: 3300cm -1 The -OH peak near the location, the 1H NMR spectrum is as follows Figure 5 As shown, the characteristic features are two sets of peaks at 2.7 and 3.7 ppm.

[0153] Application Example 3-A

[0154] Application of binder SBR-OH in composite electrolyte membrane in Example 3

[0155] Dissolve 1g of SBR-OH binder in 300mL of p-xylene solution, and add 99g of Li 5.6 PS 4.6 Cl 1.4 The sulfide electrolyte was added to the solution, stirred to ensure uniform dispersion, and finally cast onto a polytetrafluoroethylene plate to evaporate the solvent, yielding Li. 5.6 PS 4.6 Cl 1.4 - (SBR-OH) composite electrolyte membrane.

[0156] Application of Comparative Example 3-A

[0157] Application of SBR binder in composite electrolyte membranes

[0158] Dissolve 1 g of SBR in 300 mL of p-xylene solution, and add 99 g of Li 5.6 PS 4.6 Cl 1.4 The sulfide electrolyte was added to the solution, stirred to ensure uniform dispersion, and finally cast onto a polytetrafluoroethylene plate to evaporate the solvent, yielding Li. 5.6 PS 4.6 Cl 1.4 -SBR composite electrolyte membrane.

[0159] Application Example 3-B

[0160] Application of binder SBR-OH in all-solid-state lithium-ion batteries in Example 3

[0161] According to LiNi0.93 Co 0.03 Mn 0.04 The pulp was prepared using a mass ratio of O2:LPSC:C65:SBR-OH = 85:15:1:0.5. First, the SBR-OH binder was dissolved in anhydrous toluene, and then LiNi... 0.93 Co 0.03 Mn 0.04 O2, Li 5.6 PS 4.6 Cl 1.4 Sulfide solid electrolyte and conductive carbon black C65 are added to the above mixture and stirred at 500 rpm for 4 hours to obtain a uniform slurry. The slurry is then cast onto aluminum foil and subsequently dried in a vacuum oven at 80°C for 12 hours to obtain a composite positive electrode sheet.

[0162] The dried positive electrode sheet was cut into 10mm diameter positive electrode sheets on a manual slicing machine. The electrolyte membrane in Application Example 3-A was selected as the intermediate electrolyte membrane layer, and lithium indium alloy was selected as the negative electrode. The battery was assembled and cycled in a glove box.

[0163] Application of Comparative Example 3-B

[0164] Application of SBR binder in all-solid-state lithium-ion batteries

[0165] According to LiNi 0.93 Co 0.03 Mn 0.04 The pulp was prepared using a mass ratio of O2:LPSC:C65:SBR = 85:15:1:0.5.

[0166] First, dissolve the SBR binder in anhydrous toluene, then add LiNi 0.93 Co 0.03 Mn 0.04 O2, Li 5.6 PS 4.6 Cl 1.4 Sulfide electrolyte and conductive carbon black C65 are added to the above solvent and stirred at 500 rpm for 4 hours to obtain a uniform slurry. The slurry is then cast onto aluminum foil and subsequently dried in a vacuum oven at 80°C for 12 hours to obtain a composite positive electrode sheet.

[0167] The dried electrode sheets were cut into positive electrode sheets with a diameter of 10 mm on a manual slicing machine. The electrolyte membrane in Application Example 3-A was selected as the intermediate electrolyte membrane layer, and lithium indium alloy was selected as the negative electrode. The batteries were assembled and cycled in a glove box.

[0168] Comparative Example 1

[0169] Preparation of solid-state battery binder SBS-COOH

[0170] (1) Weigh 1g of SBS and add it to the reaction vessel, then add 30 mL of anhydrous xylene and stir for 1 hour to completely dissolve and disperse evenly until there is no precipitate.

[0171] (2) Add 30 mg of 1-hydroxycyclohexylphenyl ketone and 1 mL of mercaptoacetic acid to the reaction solution, stir for 2 h, and after stirring evenly, carry out the grafting reaction for 1 h under ultraviolet light irradiation. The reaction temperature is 25℃ and the ultraviolet light wavelength is 380 nm.

[0172] (3) After the reaction is complete, the reaction solution is poured into methanol, and the precipitate is dissolved in xylene. This process is repeated three times. The precipitate is then placed in a freeze dryer and dried for 24 hours to obtain solid battery binder (SBS-COOH).

[0173] The molecular formula of SBS-COOH is (C8H8). m (CH2CH=CHCH2) n (C8H8) k (C5H 11 SCOOH) h [CH2CH(CH=CH2)] j Where m+k≈440, n+h+j≈2600; the grafting rate is 8.2%.

[0174] Application of Comparative Example 4-A

[0175] The process was similar to that in Application Example 1-A, except that the SBS-OH binder was replaced with an equal mass of SBS-COOH binder, while all other aspects remained unchanged, to prepare the composite electrolyte membrane.

[0176] Application of Comparative Example 4-B

[0177] The process was similar to that in Application Example 1-B, except that the SBS-OH binder was replaced with an equal mass of SBS-COOH binder, while all other aspects remained unchanged, to prepare a solid-state battery.

[0178] Comparative Example 2

[0179] Preparation of solid-state battery binder SBS-OH

[0180] The process was similar to that in Example 1, except that the molar ratio of mercaptoethanol to the carbon-carbon double bonds in SBS was adjusted to prepare a solid-state battery binder SBS-OH with a grafting rate of 11.9%. The specific method is as follows:

[0181] (1) Weigh 1g of SBS and add it to the reaction vessel, then add 30 mL of anhydrous xylene and stir for 1 hour to completely dissolve and disperse evenly until there is no precipitate.

[0182] (2) Add 30 mg of 1-hydroxycyclohexylphenyl ketone and 5 mL of mercaptoethanol to the reaction solution, stir for 2 h, and after stirring evenly, carry out the grafting reaction for 1 h under ultraviolet light irradiation. The reaction temperature is 25℃ and the ultraviolet light wavelength is 380 nm.

[0183] (3) After the reaction was completed, the reaction solution was poured into methanol, and it was found that the precipitate could no longer be dissolved in xylene.

[0184] The product prepared in this comparative example has poor solubility in xylene, which does not meet the requirement that sulfide solid-state battery binders must be soluble in medium to low polarity solvents.

[0185] Comparative Example 3

[0186] The process was similar to that in Example 1, except that the molar ratio of mercaptoethanol to the carbon-carbon double bonds in SBS was adjusted to prepare a solid-state battery binder SBS-OH with a grafting rate of 3.6%. The specific method is as follows:

[0187] (1) Weigh 1g of SBS and add it to the reaction vessel, then add 30 mL of anhydrous xylene and stir for 1 hour to completely dissolve and disperse evenly until there is no precipitate.

[0188] (2) Add 30 mg of 1-hydroxycyclohexylphenyl ketone and 0.5 mL of mercaptoethanol to the reaction solution, stir for 2 h, and after stirring evenly, carry out the grafting reaction for 1 h under ultraviolet light irradiation. The reaction temperature is 25℃ and the ultraviolet light wavelength is 380 nm.

[0189] (3) After the reaction is complete, pour the reaction solution into methanol, dissolve the precipitate in xylene, repeat three times, and then place the precipitate in a freeze dryer to dry for 24 hours.

[0190] The comparative example yielded an SBS-OH binder with a low grafting rate.

[0191] Application Comparative Example 5-A

[0192] The process was similar to that of Application Example 1-A, except that the SBS-OH binder prepared in Example 1 was replaced with an equal mass of the SBS-OH binder prepared in Comparative Example 3, while all other aspects remained unchanged, to prepare a composite electrolyte membrane.

[0193] Application of Comparative Example 5-B

[0194] The process was similar to that of Application Example 1-B, except that the SBS-OH binder prepared in Example 1 was replaced with an equal mass of the SBS-OH binder prepared in Comparative Example 3, while all other aspects remained unchanged, to prepare a solid-state battery.

[0195] Test Example 1

[0196] The ionic conductivity and impedance of the sulfide composite electrolyte membranes prepared in the above examples were tested. The impedance diagram of the composite electrolyte membranes at 25°C is shown below. Figure 8 and Figure 11 As shown, where Figure 8 In the figures, (a) represents the impedance diagrams of the composite electrolyte membranes of Application Example 1-A and Application Comparative Example 1-A; (b) represents the impedance diagrams of the composite electrolyte membranes of Application Example 2-A and Application Comparative Example 2-A; and (c) represents the impedance diagrams of the composite electrolyte membranes of Application Example 3-A and Application Comparative Example 3-A. Figure 11 Impedance diagram of the composite electrolyte membrane corresponding to Comparative Example 5-A at 25°C.

[0197] Ion conductivity was tested using the following method:

[0198] (i) Take a sulfide composite electrolyte membrane with a diameter of Φ=10mm;

[0199] (ii) Stainless steel was attached to both sides of the sulfide composite electrolyte membrane as a current collector, and the sample to be tested was obtained by pressing it at 150 MPa;

[0200] (iii) The impedance of the sample I to be tested was measured using an electrochemical workstation to obtain an AC impedance spectrum, and the impedance of the sulfide composite electrolyte membrane was obtained. The impedance was then calculated using the formula σ = L / R 1 S Calculate the room temperature ionic conductivity σ of the sulfide composite electrolyte membrane, where L is the thickness of the sulfide composite electrolyte membrane (in mm), R1 is the impedance of the sulfide composite electrolyte membrane (in Ω), and S is the contact area (in cm²). 2 ).

[0201] The physical and chemical properties of the composite electrolyte membrane are shown in Table 1.

[0202] Table 1

[0203]

[0204] The results above show that the composite electrolyte membrane prepared using the solid-state battery binder provided by this invention has low impedance and high ionic conductivity, and has better application prospects.

[0205] Test Example 2

[0206] Electrochemical performance tests were conducted on the batteries assembled in each application example and application comparison example using a constant current charge-discharge method. The test conditions were constant temperature at 25°C, voltage range of 2.4-3.7V, and cycling at a rate of 0.1C. All battery tests were performed in a glove box.

[0207] Constant current charge and discharge can control the current and voltage during the charging and discharging process, simulate the charging and discharging behavior of the battery in actual use, evaluate the battery's performance indicators such as capacity, energy density, and coulombic efficiency, and predict the battery's cycle life.

[0208] The specific results are shown in Table 2.

[0209] Table 2

[0210]

[0211] Figure 6 The diagram shows the cycle performance of batteries assembled in Application Example 1-B and Comparative Example 1-B of the present invention at 0.1C current and 25°C.

[0212] Figure 7 Impedance diagrams of batteries assembled in Application Example 1-B and Comparative Example 1-B of the present invention after 0.1C current, 25°C, and 100 cycles are shown.

[0213] Figure 9 The diagram shows the cycle performance of the battery assembled using Comparative Example 5-B at 0.1C current and 25°C.

[0214] Figure 10 The impedance diagram of the battery assembled using Comparative Example 5-B is shown after 100 cycles at 0.1C current and 25°C.

[0215] As can be seen from the above results, the sulfur-based solid-state battery prepared using the solid-state battery binder provided by this invention has a much better capacity retention rate than the comparative example after the first efficiency and 100 cycles, and has superior electrochemical performance.

[0216] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A solid-state battery binder, characterized in that, The solid-state battery binder is a product obtained by grafting a group of formula (I) onto a nonpolar unsaturated rubber; the grafting rate of the group of formula (I) is 5-10%. -SR-OH formula (I) Where R is -CH2CH2-; The nonpolar unsaturated rubber includes styrene-butadiene-styrene block copolymers and / or butadiene rubber; The solid-state battery binder is a product obtained by grafting -S-CH2CH2-OH onto a styrene-butadiene-styrene block copolymer, and the molecular formula of the solid-state battery binder is (C8H8). m (CH2CH=CHCH2) n (C8H8) k (C6H 11 SOH) h [CH2CH(CH=CH2)] j Where m+k takes values ​​of 430-450, and n+h+j takes values ​​of 2500-2700; And / or, the solid-state battery binder is a product obtained by grafting -S-CH2CH2-OH onto butadiene rubber, and the molecular formula of the solid-state battery binder is (CH2CH=CHCH2). m (C6H 11 SOH) n , where m+n takes values ​​from 6100 to 6300.

2. The solid-state battery binder according to claim 1, characterized in that, The weight-average molecular weight of the nonpolar unsaturated rubber is 50,000 to 300,000.

3. A method for preparing the solid-state battery binder according to claim 1 or 2, characterized in that, The method includes: In the presence of benzene-based solvents and photoinitiators, a nonpolar unsaturated rubber and the compound shown in formula (II) are grafted to obtain a solid battery binder; the molar ratio of the compound shown in formula (II) to the carbon-carbon double bonds contained in the nonpolar unsaturated rubber is 0.5-5:

1. HS-R-OH formula (II) Where R stands for -CH2CH2-.

4. The method according to claim 3, characterized in that, The photoinitiator includes at least one of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-2-phenylethyl ketone, ethyl 2,4,6-trimethylbenzoylphosphonate, and 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone; And / or, the benzene solvent includes at least one of benzene, toluene, o-xylene, m-xylene, p-xylene, and anisole.

5. The method according to claim 3 or 4, characterized in that, The molar ratio of the photoinitiator to the carbon-carbon double bonds contained in the nonpolar unsaturated rubber is 0.01-0.05:1; And / or, the grafting reaction is carried out under ultraviolet light irradiation, and the conditions of the grafting reaction include: a temperature of 10-50°C and a time of 10 min to 5 h.

6. The application of the solid-state battery binder according to claim 1 or 2 in sulfide-based all-solid-state batteries.

7. A composite electrolyte membrane, characterized in that, The composite electrolyte membrane contains a sulfide electrolyte and a solid-state battery binder; based on the total mass of the composite electrolyte membrane, the content of the sulfide electrolyte is 80-99 wt%, and the content of the solid-state battery binder is 1-20 wt%. The solid-state battery binder is the solid-state battery binder according to claim 1 or 2.

8. A composite positive electrode for a solid-state battery, characterized in that, The solid-state battery composite cathode includes: Active materials, conductive agents, sulfide electrolytes, solid-state battery binders; The solid-state battery binder is the solid-state battery binder according to claim 1 or 2.

9. The solid-state battery composite cathode according to claim 8, characterized in that, The active substance includes at least one of the following: the compound shown in formula (1), the compound shown in formula (2), the compound shown in formula (3), the compound shown in formula (4), and the compound shown in formula (5); Formula (1): LiCoO2; Equation (2): LiNi x1 Mn y1 Co 1-x1-y1 O2; Formula (3): LiNi 1-x2-y2 Co x2 Al y2 O2; Equation (4): LiNi x3 Mn 1-x3 O2; Equation (5): Li 1+x4 EO2; Among them, x1, x2, x3, x4, y1, and y2 are each independently selected from any value between 0 and 1; E is selected from any one of Mn, Ni, Co, and Al.

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