Phosphorus-based cross-linking agent containing silyl ether, gel-state polymer electrolyte, solid-state pole piece and lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a silicon ether-containing phosphorus-based cross-linking agent, a gel-state polymer electrolyte, a solid-state pole piece and a lithium ion battery. Compared with the prior art, the phosphorus-based cross-linking agent containing silyl ether provided by the invention has a multi-site cross-linking structure, so that the polymerization degree of a polymer can be effectively improved; besides, singlet oxygen and HF in the charging process can be effectively removed due to the existence of a phosphate or phosphite structure in the phosphorus-based cross-linking agent, so that the battery keeps good cycling stability and safety and has high safety; moreover, the existence of silicon-oxygen bonds in the phosphorus-based cross-linking agent can promote ion mobility, and the phosphorus-based cross-linking agent has high ion conductivity, can reduce polarization and improve energy density, and is suitable for high-voltage / high-energy density batteries.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, and particularly relates to a phosphorus-based crosslinking agent containing silicon ether, a gel polymer electrolyte, a solid electrode, and a lithium-ion battery. Background Technology

[0002] In the context of carbon neutrality, lithium-ion batteries have developed rapidly, but at the same time, higher requirements have been placed on the energy density, safety, and lifespan of lithium-ion batteries.

[0003] Nickel-rich ternary cathode material LiNi x Co y Mn z O2 (x+y+z=1) has attracted widespread attention due to its high theoretical capacity and high operating voltage, resulting in high energy density. High-nickel cathode materials often improve the reversible capacity and energy density of batteries by increasing the nickel content, but they also face many challenges. For example, currently commercially available organic liquid electrolytes based on lithium hexafluorophosphate have been subject to Lewis acid PF5... - The resulting corrosion by HF, accompanied by structural and morphological degradation, along with structural and morphological deterioration such as transition metal dissolution, lattice oxygen escape during charging and discharging, and microcracks, are common failure modes of high-nickel (NCM) cathodes. Studies have shown that oxygen loss is observed at the end of charging in all layered oxide cathodes, and the onset potential of oxygen loss decreases with increasing nickel content. Oxygen loss makes transition metal atoms more mobile, promotes surface phase transitions, and damages and corrodes the cathode electrolyte interphase (CEI), leading to a series of serious consequences such as changes in cathode structure and increased impedance, ultimately causing a sharp deterioration in battery electrical and safety performance. Therefore, removing singlet oxygen generated during charging has become an urgent problem to be solved when using high-nickel ternary materials as cathodes.

[0004] Electrolytes, as the "blood" of batteries, also play a crucial role. Traditional lithium-ion batteries typically use liquid electrolytes, which, while possessing high lithium-ion conductivity, contain a large amount of alkyl carbonate solvents. These solvents are easily oxidized and decomposed under high pressure, and under various abuse conditions, can easily cause battery leakage, explosion, fire, and other safety hazards. While all-solid-state batteries can greatly improve the safety of lithium-ion batteries, technical bottlenecks such as low ionic conductivity and high interfacial impedance (between the electrode and the electrolyte) have prevented their large-scale application.

[0005] Against this backdrop, gel polymer electrolytes (GPEs) have been extensively studied. These systems utilize polymer networks to physically bind or chemically immobilize liquid solvents and lithium salts, forming a three-dimensional cross-linked gel system. GPEs not only possess superior ion transport capabilities and lower interfacial impedance compared to solid electrolytes, but also retain the safety characteristics of solid electrolytes. However, compared to liquid electrolytes, they still exhibit lower ionic conductivity, and the encapsulation of flammable solvent molecules and plasticizers within the polymer backbone poses certain safety hazards. Therefore, the flame retardancy of GPEs needs further improvement. Summary of the Invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a phosphorus-based crosslinking agent containing silicon ether, a gel polymer electrolyte, a solid electrode, and a lithium-ion battery. The phosphorus-based crosslinking agent can effectively improve the degree of polymerization and ionic conductivity of the polymer, promote ion mobility, remove singlet oxygen and HF during the charging process, and enable the battery to maintain good cycle stability and safety.

[0007] This invention provides a phosphorus-based crosslinking agent containing a silyl ether, having the structure shown in formula (I) or formula (II):

[0008] Formula (I); Equation (II);

[0009] R1 and R2 are each independently selected from substituted or unsubstituted C1~C10 alkyl, substituted or unsubstituted C2~C10 alkenyl, or substituted or unsubstituted C6~C10 aryl.

[0010] R3 is selected from substituted or unsubstituted C2~C10 alkenyl groups;

[0011] The substituents in the substituted C1-C10 alkyl, substituted C2-C10 alkenyl and substituted C6-C10 aryl groups are each independently selected from one or more of the C1-C10 alkyl, C2-C10 alkenyl and C6-C10 aryl groups.

[0012] The A is selected from O or S.

[0013] Preferably, it has the structure shown in formula (III) or formula (IV):

[0014] Formula (III); Formula (IV).

[0015] Preferably, R1 and R2 are each independently selected from substituted or unsubstituted C1-C3 alkyl, substituted or unsubstituted C2-C3 alkenyl, or substituted or unsubstituted C6-C10 aryl.

[0016] The substituents in the substituted C1-C3 alkyl, substituted C2-C3 alkenyl, and substituted C6-C10 aryl groups are each independently selected from one or more of the C1-C3 alkyl, C2-C3 alkenyl, and C6-C10 aryl groups.

[0017] Preferably, R1 and R2 are selected from methyl groups.

[0018] The present invention also provides a gel-state polymer electrolyte formed from an electrolyte precursor solution; the electrolyte precursor solution includes the above-mentioned silyl ether-containing phosphorus-based crosslinking agent, acrylate monomer, lithium salt, organic solvent and initiator.

[0019] Preferably, the total mass of the phosphorus-based crosslinking agent containing silicon ether and the acrylate monomer is 3% to 20% of the mass of the electrolyte precursor solution; the mass ratio of the phosphorus-based crosslinking agent containing silicon ether to the acrylate monomer is (1 to 4): (6 to 9).

[0020] Preferably, the mass of the lithium salt is 5% to 20% of the mass of the electrolyte precursor solution;

[0021] And / or, the initiator is 0.1% to 5% of the total mass of the silyl ether-containing phosphorus-based crosslinking agent and the acrylate monomer;

[0022] And / or, the acrylate monomers are selected from one or more of methyl acrylate, ethyl acrylate, methyl methacrylate and ethyl methacrylate;

[0023] And / or, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(oxalato)borate, lithium difluorooxalato)borate, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(fluorosulfonyl)imide.

[0024] And / or, the organic solvent is selected from one or more of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate;

[0025] And / or, the initiator is selected from azobisisobutyronitrile and / or azobisisoheptanenitrile.

[0026] The present invention also provides a solidified electrode, comprising a current collector and a modified active layer attached to at least one surface of the current collector;

[0027] The modified active layer comprises a crosslinked polymer and an active material; the raw materials for forming the crosslinked polymer include the aforementioned phosphorus-based crosslinking agent containing silicon ether and acrylate monomers; the active material is selected from positive electrode materials or negative electrode materials.

[0028] Preferably, the mass of the crosslinked polymer is 0.1% to 15% of the mass of the modified active layer;

[0029] And / or, the mass ratio of the silyl ether-containing phosphorus-based crosslinking agent to the acrylate monomer is (1~4):(6~9).

[0030] The present invention also provides a lithium-ion battery comprising the above-described gel polymer electrolyte and / or the above-described solidified electrode.

[0031] Compared with the prior art, the phosphorus-based crosslinking agent containing silicon ether provided by the present invention has a multi-site crosslinking structure, which can effectively improve the degree of polymerization of the polymer; in addition, the presence of phosphate ester or phosphite structure in the phosphorus-based crosslinking agent can effectively remove singlet oxygen and HF during charging, so that the battery maintains good cycle stability and safety, and has high safety; furthermore, the presence of silicon-oxygen bonds in the phosphorus-based crosslinking agent can promote ion mobility, have high ionic conductivity, reduce polarization, improve energy density, and be suitable for high voltage / high energy density batteries. Attached Figure Description

[0032] Figure 1 The 1H NMR spectrum of the tris(vinyldimethylsilyl)phosphate prepared in Example 1 of this invention;

[0033] Figure 2 The 1H NMR spectrum of the tris(vinyldimethylsilyl)thiophosphate prepared in Example 2 of this invention;

[0034] Figure 3 The 1H NMR spectrum of tris(vinyldimethylsilyl)phosphite prepared in Example 3 of this invention;

[0035] Figure 4 The graph shows the cycle performance results of the pouch cells obtained in Embodiment 4, Comparative Example 1, and Comparative Example 2 of the present invention. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] This invention provides a phosphorus-based crosslinking agent containing a silyl ether, having the structure shown in formula (I) or formula (II):

[0038] Formula (I); Equation (II);

[0039] Wherein, R1 and R2 are each independently a substituted or unsubstituted C1-C10 alkyl, a substituted or unsubstituted C2-C10 alkenyl, or a substituted or unsubstituted C6-C10 aryl; R3 is a substituted or unsubstituted C2-C10 alkenyl; the substituents in the substituted C1-C10 alkyl, substituted C2-C10 alkenyl, and substituted C6-C10 aryl are each independently one or more of C1-C10 alkyl, C2-C10 alkenyl, and C6-C10 aryl; and A is O or S.

[0040] In a specific embodiment of the present invention, R1 and R2 are each preferably independently substituted or unsubstituted C1-C8 alkyl, substituted or unsubstituted C2-C8 alkenyl, or substituted or unsubstituted C6-C10 aryl; the substituents in the substituted C1-C8 alkyl, substituted C2-C8 alkenyl, and substituted C6-C10 aryl are each preferably one or more of C1-C8 alkyl, C2-C8 alkenyl, and C6-C10 aryl, more preferably one or more of C1-C6 alkyl, C2-C6 alkenyl, and C6-C10 aryl, even more preferably one or more of C1-C4 alkyl, C2-C4 alkenyl, and C6-C10 aryl, even more preferably one or more of C1-C3 alkyl, C2-C3 alkenyl, and C6-C10 aryl, and most preferably one or more of methyl, ethyl, vinyl, and phenyl.

[0041] In a specific embodiment of the present invention, R1 and R2 are each preferably independently substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C2-C6 alkenyl, or substituted or unsubstituted C6-C10 aryl; the substituents in the substituted C1-C6 alkyl, substituted C2-C6 alkenyl, and substituted C6-C10 aryl are each preferably one or more of C1-C6 alkyl, C2-C6 alkenyl, and C6-C10 aryl, more preferably one or more of C1-C4 alkyl, C2-C4 alkenyl, and C6-C10 aryl, even more preferably one or more of C1-C3 alkyl, C2-C3 alkenyl, and C6-C10 aryl, and most preferably one or more of methyl, ethyl, vinyl, and phenyl.

[0042] In a specific embodiment of the present invention, R1 and R2 are each preferably independently substituted or unsubstituted C1-C4 alkyl, substituted or unsubstituted C2-C4 alkenyl, or substituted or unsubstituted C6-C10 aryl; the substituents in the substituted C1-C4 alkyl, substituted C2-C4 alkenyl, and substituted C6-C10 aryl are each preferably one or more of C1-C4 alkyl, C2-C4 alkenyl, and C6-C10 aryl, more preferably one or more of C1-C3 alkyl, C2-C3 alkenyl, and C6-C10 aryl, and even more preferably one or more of methyl, ethyl, vinyl, and phenyl.

[0043] In a specific embodiment of the present invention, R1 and R2 are each preferably independently substituted or unsubstituted C1-C3 alkyl, substituted or unsubstituted C2-C3 alkenyl, or substituted or unsubstituted C6-C10 aryl; the substituents in the substituted C1-C3 alkyl, substituted C2-C3 alkenyl, and substituted C6-C10 aryl are each preferably one or more of C1-C3 alkyl, C2-C3 alkenyl, and C6-C10 aryl, more preferably one or more of methyl, ethyl, vinyl, and phenyl.

[0044] In one specific embodiment of the present invention, R1 and R2 are each preferably methyl, ethyl, vinyl, or phenyl.

[0045] In a specific embodiment of the present invention, R3 is preferably a substituted or unsubstituted C2-C8 alkenyl group; the substituent in the substituted C2-C8 alkenyl group is preferably one or more of C1-C8 alkyl, C2-C8 alkenyl and C6-C10 aryl, more preferably one or more of C1-C6 alkyl, C2-C6 alkenyl and C6-C10 aryl, even more preferably one or more of C1-C4 alkyl, C2-C4 alkenyl and C6-C10 aryl, even more preferably one or more of C1-C3 alkyl, C2-C3 alkenyl and C6-C10 aryl, and most preferably one or more of methyl, ethyl, vinyl and phenyl.

[0046] In a specific embodiment of the present invention, R3 is preferably a substituted or unsubstituted C2-C6 alkenyl group; the substituent in the substituted C2-C6 alkenyl group is preferably one or more of C1-C6 alkyl, C2-C6 alkenyl and C6-C10 aryl, more preferably one or more of C1-C4 alkyl, C2-C4 alkenyl and C6-C10 aryl, even more preferably one or more of C1-C3 alkyl, C2-C3 alkenyl and C6-C10 aryl, and most preferably one or more of methyl, ethyl, vinyl and phenyl.

[0047] In a specific embodiment of the present invention, R3 is preferably a substituted or unsubstituted C2-C4 alkenyl group; the substituent in the substituted C2-C4 alkenyl group is preferably one or more of C1-C4 alkyl, C2-C4 alkenyl and C6-C10 aryl, more preferably one or more of C1-C3 alkyl, C2-C3 alkenyl and C6-C10 aryl, and even more preferably one or more of methyl, ethyl, vinyl and phenyl.

[0048] In one specific embodiment of the present invention, R3 is preferably a substituted or unsubstituted C2-C3 alkenyl group; the substituent in the substituted C2-C3 alkenyl group is preferably one or more of C1-C3 alkyl, C2-C3 alkenyl and C6-C10 aryl, more preferably one or more of methyl, ethyl, vinyl and phenyl.

[0049] In one specific embodiment of the present invention, the silyl ether-containing phosphorus-based crosslinking agent has the structure shown in formula (III) or formula (IV):

[0050] Formula (III); Formula (IV);

[0051] R1 and R2 are the same as described above, and will not be repeated here.

[0052] In one specific embodiment of the present invention, the phosphorus-based crosslinking agent containing silyl ether has the structure shown in formula (III) or formula (IV), and R1 and R2 are both methyl.

[0053] The phosphorus-based crosslinking agent containing silicon ethers provided by this invention introduces lone pairs of electrons from phosphites or phosphates, which can effectively remove singlet oxygen, reducing gas generation in the battery. Furthermore, phosphorus compounds are also effective flame retardants. In addition, the introduced Si-O bonds provide effective lithium-ion migration channels, accelerating the migration rate of lithium ions and effectively removing harmful substances such as HF. Moreover, because electrophilic phosphorus and silicon readily remove nucleophilic lithium oxides through chemical scavenging reactions, this crosslinking agent can significantly improve the overall chemical stability of the electrolyte.

[0054] The present invention also provides a gel-state polymer electrolyte formed from an electrolyte precursor solution; the electrolyte precursor solution includes the above-mentioned phosphorus-based crosslinking agent containing silicon ether, acrylate monomers, lithium salts, organic solvents, and initiators.

[0055] The phosphorus-based crosslinking agent containing silicon ether provided by this invention has a multi-site crosslinking structure, which can rapidly polymerize with carbonates in the presence of thermal initiators / photoinitiators to achieve a high degree of polymerization. Furthermore, the lone pairs of electrons in phosphites or phosphates can effectively remove singlet oxygen generated during charging, which helps to improve the cycle stability of the battery. In addition, the contained silicon-oxygen bonds can provide an effective lithium-ion transport channel, accelerate the migration rate of lithium ions, improve ionic conductivity, and effectively remove HF, suppressing battery gas generation. Moreover, since the electrophilic phosphorus and silicon can remove nucleophilic lithium oxides through chemical removal reactions, this crosslinking agent can greatly improve the overall chemical stability of the electrolyte.

[0056] In one specific embodiment of the present invention, the total mass of the phosphorus-based crosslinking agent containing silicone ether and the acrylate monomer is preferably 3% to 20% of the mass of the electrolyte precursor solution; optionally, the total mass of the phosphorus-based crosslinking agent containing silicone ether and the acrylate monomer is preferably 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20% of the mass of the electrolyte precursor solution or a range between any two of the above values.

[0057] In a specific embodiment of the present invention, the total mass of the silyl ether-containing phosphorus-based crosslinking agent and the acrylate monomer is preferably 10% to 15% of the mass of the electrolyte precursor solution, more preferably 12% to 15%, and even more preferably 13% to 15%.

[0058] In one specific embodiment of the present invention, the preferred mass ratio of the phosphorus-based crosslinking agent containing silicone ether to the acrylate monomer is (1~4):(6~9); optionally, the mass ratio of the phosphorus-based crosslinking agent containing silicone ether to the acrylate monomer is 1:9, 2:8, 3:7, 4:6 or any two of the above ratios.

[0059] In one specific embodiment of the present invention, the acrylate monomer can be any acrylate monomer well known to those skilled in the art, and there are no special limitations, including but not limited to one or more of methyl acrylate, ethyl acrylate, methyl methacrylate and ethyl methacrylate.

[0060] In one specific embodiment of the present invention, the mass of the lithium salt is preferably 5% to 20% of the mass of the electrolyte precursor solution; optionally, the mass of the lithium salt is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20% of the mass of the electrolyte precursor solution or a range between any two of the above values.

[0061] In one specific embodiment of the present invention, the mass of the lithium salt is preferably 10% to 15% of the mass of the electrolyte precursor solution.

[0062] In one specific embodiment of the present invention, the lithium salt can be any lithium salt well known to those skilled in the art, and there are no special limitations, including but not limited to one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(oxaloyl)borate (LiBOB), lithium difluorooxaloylborate (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium bis(fluorosulfonyl)imide (LiFSI).

[0063] In one specific embodiment of the present invention, the mass of the organic solvent is preferably 50% to 85% of the mass of the electrolyte precursor solution; optionally, the mass of the organic solvent is 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% of the mass of the electrolyte precursor solution or a range between any two of the above values.

[0064] In one specific embodiment of the present invention, the mass of the organic solvent is preferably 60% to 75% of the mass of the electrolyte precursor solution.

[0065] In one specific embodiment of the present invention, the organic solvent is preferably a carbonate solvent, and more preferably includes, but is not limited to, one or more of ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC).

[0066] In one specific embodiment of the present invention, the organic solvent includes cyclic carbonates and chain carbonates; the cyclic carbonate is preferably ethylene carbonate (EC) and / or propylene carbonate (PC); the chain carbonate is preferably one or more of diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC); the volume ratio of the cyclic carbonate to the chain carbonate is preferably (1~3):(2~4); optionally, the volume ratio of the cyclic carbonate to the chain carbonate is 1:2, 1:3, 1:4, 2:2, 2:3, 2:4, 3:2, 3:4, or any two of the above ratios.

[0067] In one specific embodiment of the present invention, the organic solvent includes cyclic carbonates and chain carbonates; the volume ratio of the cyclic carbonates to the chain carbonates is preferably 2:3.

[0068] In one specific embodiment of the present invention, the mass of the initiator is preferably 0.1% to 5% of the total mass of the silyl-containing phosphorus-based crosslinking agent and the acrylate monomer; optionally, the mass of the initiator is preferably 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or any two of the above values.

[0069] In one specific embodiment of the present invention, the initiator is preferably a thermal initiator or a photoinitiator.

[0070] In one specific embodiment of the present invention, the initiator is preferably a thermal initiator, more preferably an azo initiator, and even more preferably azobisisobutyronitrile (AIBN) and / or azobisisoheptanenitrile.

[0071] In one specific embodiment of the invention, the electrolyte precursor solution preferably further includes additives; the additives can be additives well known to those skilled in the art and are not particularly limited. In this invention, it is preferred to include, but not limited to, one or more of nitrile additives, sulfonates, sulfates, fluorinated additives, unsaturated cyclic carbonates, borates, trimethylsilyl esters, and fluorinated lithium salts; the nitrile additives preferably include, but not limited to, butadione, 1,3,6-hexanetricarbonate, trans-hexenedione, 1,2-di(cyanoethoxy)ethane, 3-(trimethylsiloxy)propionitrile, and bis(cyanoethyl) sulfone; the fluorinated additives preferably include, but not limited to, fluoroethylene carbonate, trifluoropropylene carbonate, 1,1,1,3,3,3-hexafluoroisopropyl methyl ether, and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether; the sulfonic acid... The ester compounds preferably include, but are not limited to, one or more of 1,3-propanesulfonyl lactone, 1,4-butanesulfonyl lactone, methanedisulfonate, and 1,3-propenesulfonate; the sulfate ester compounds preferably include, but are not limited to, vinyl sulfate, trimethylene cyclic sulfate, methyl vinyl sulfate, 4,4'-divinyl sulfate, and propylene sulfite; the unsaturated cyclic carbonate compounds preferably include, but are not limited to, vinylene carbonate and / or vinyl vinyl carbonate; the borate ester compounds preferably include, but are not limited to, one or more of trimethyl borate, triethyl borate, tripropyl borate, tributyl borate, and triphenyl borate; the trimethylsilyl ester compounds preferably include, but are not limited to, tris(trimethylsilyl)borate, tris(trimethylsilyl)phosphate, tris(trimethylsilyl)phosphite, and tris(trimethylsilyl)trifluoromethanesulfonate; and the fluorinated lithium salt compounds preferably include, but are not limited to, lithium difluorophosphate.

[0072] In this invention, the gel polymer electrolyte can be prepared according to methods well known to those skilled in the art. In a specific embodiment provided by this invention, it is preferably prepared by the following steps: mixing an organic solvent, a lithium salt, a phosphorus-based crosslinking agent containing a silicon ether, and an acrylate monomer, and then adding an initiator to obtain a precursor solution; injecting the precursor solution into a battery semi-finished product and polymerizing it in situ to obtain the gel polymer electrolyte. The battery semi-finished product includes a positive electrode, a negative electrode, and a separator.

[0073] The present invention also provides a solidified electrode, comprising a current collector and a modified active layer attached to at least one surface of the current collector; the modified active layer comprises a crosslinked polymer and an active material; the raw materials for forming the crosslinked polymer include the above-mentioned phosphorus-based crosslinking agent containing silicon ether and acrylate monomers; the active material is a positive electrode material or a negative electrode material.

[0074] In one specific embodiment of the present invention, the mass of the crosslinked polymer is preferably 0.1% to 15% of the mass of the modified active layer; optionally, the mass of the polymer of the silyl ether-containing phosphorus-based crosslinking agent and the acrylate monomer is 0.1%, 0.3%, 0.5%, 0.7%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% of the mass of the modified active layer or a range between the above two values.

[0075] In a specific embodiment of the present invention, the preferred mass ratio of the phosphorus-based crosslinking agent containing silane to the acrylate monomer in the crosslinked polymer is (1~4):(6~9); optionally, the mass ratio of the phosphorus-based crosslinking agent containing silane to the acrylate monomer in the polymer is 1:9, 2:8, 3:7, 4:6 or any two of the above ratios.

[0076] In a specific embodiment of the present invention, the mass of the active material is preferably 85% to 98% of the mass of the modified active layer, more preferably 90% to 98%, and even more preferably 90% to 95%.

[0077] In one specific embodiment of the present invention, the cathode material can be any cathode material well known to those skilled in the art, and there are no special limitations, including but not limited to lithium iron phosphate (LiFePO4), lithium manganese oxide (LiMnO4), lithium cobalt oxide (LiCoO2), and ternary cathode materials (LiNi). x Co y Mn z One or more of O2 and lithium-rich manganese-based (Li2MnO3), more preferably NCM811, NCM523, NCM622, LCO, LMO or LNMO.

[0078] In one specific embodiment of the present invention, the cathode material is preferably a layered cathode material.

[0079] In one specific embodiment of the present invention, the active material is a positive electrode material, the solidified electrode sheet is a solidified positive electrode sheet, and the current collector is preferably aluminum foil.

[0080] In one specific embodiment of the present invention, the negative electrode material can be any negative electrode material well known to those skilled in the art, and there are no special limitations. It includes, but is not limited to, one or more of natural graphite (NG), artificial graphite (AG), hard carbon / soft carbon, silicon carbide (SiC), etc., with SiC being preferred.

[0081] In one specific embodiment of the present invention, the active material is a negative electrode material, the solidified electrode sheet is a solidified negative electrode sheet, and the current collector is a copper foil.

[0082] In a specific embodiment of the present invention, the modified active layer preferably further includes a conductive agent; the conductive agent can be any conductive agent well known to those skilled in the art, and there are no special limitations. In the present invention, it preferably includes, but is not limited to, conductive carbon black (SuperP) and / or carbon nanotubes; the mass of the conductive agent is preferably 1% to 5% of the mass of the modified active layer.

[0083] In a specific embodiment of the present invention, the modified active layer preferably further includes an adhesive; the adhesive can be any adhesive well known to those skilled in the art and is not particularly limited, but is preferably polyvinylidene fluoride (PVDF) in the present invention; the mass of the adhesive is preferably 1% to 5% of the mass of the modified active layer.

[0084] In this invention, the solidified electrode sheet can be prepared according to methods well known to those skilled in the art, without any special limitations. In a specific embodiment provided by this invention, it can be prepared by the following method: The active material, conductive agent, and binder are mixed in a solvent, then a phosphorus-based crosslinking agent containing silicon ether, acrylate monomers, and an initiator are added, and the mixture is stirred to obtain a modified slurry; the modified slurry is transferred to at least one surface of a current collector, subjected to polymerization reaction, dried, and rolled to obtain a solidified electrode sheet; the type of initiator is the same as described above; the mass of the initiator is preferably 0.1% to 5% of the total mass of the phosphorus-based crosslinking agent containing silicon ether and the acrylate monomers; optionally, the mass of the initiator is preferably 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any two of the above values; the stirring speed is preferably 1000 to 3000 rpm, more preferably 1500 to 2500 rpm. The stirring and mixing time is preferably 10-40 min, more preferably 20-30 min, and even more preferably 25 min; when the initiator is a photoinitiator, the polymerization reaction is carried out under ultraviolet light irradiation; when the initiator is a thermal initiator, the polymerization reaction is carried out under heating; the polymerization temperature is preferably 40℃-50℃, more preferably 45℃; the polymerization time is preferably 10-60 min, more preferably 30-60 min, and even more preferably 45 min; the drying temperature is preferably 80℃-100℃, more preferably 90℃; the drying time is preferably 1-8 h, more preferably 3-6 h, and even more preferably 4-5 h.

[0085] The present invention also provides a lithium-ion battery comprising the above-described gel polymer electrolyte and / or the above-described solidified electrode.

[0086] In one specific embodiment of the present invention, the lithium-ion battery includes a positive electrode, a negative electrode, a separator, and the aforementioned gel polymer electrolyte.

[0087] In a specific embodiment of the present invention, the positive electrode preferably includes a positive electrode current collector and a positive electrode active layer coated on the surface of the positive electrode current collector; the positive electrode active layer includes a positive electrode material, a conductive agent, and a binder; the positive electrode material can be any positive electrode material well known to those skilled in the art, and there are no special limitations, including but not limited to lithium iron phosphate (LiFePO4), lithium manganese oxide (LiMnO4), lithium cobalt oxide (LiCoO2), and ternary cathode materials (LiNiO2). x Co y Mn z One or more of O2 and lithium-rich manganese-based (Li2MnO3), more preferably NCM811, NCM523, NCM622, LCO, LMO or LNMO; the conductive agent can be any conductive agent well known to those skilled in the art, and there are no special limitations. In this invention, conductive carbon black (SuperP) and / or carbon nanotubes are preferred; the binder can be any binder well known to those skilled in the art, and there are no special limitations. In this invention, polyvinylidene fluoride (PVDF) is preferred; the mass ratio of the positive electrode material, conductive agent and binder is preferably 90~98:1~5:1~5.

[0088] In a specific embodiment of the present invention, the negative electrode preferably includes a negative electrode current collector and a negative electrode active layer coated on the surface of the negative electrode current collector; the negative electrode active layer includes a negative electrode material, a negative electrode conductive agent, and a negative electrode binder; the negative electrode material can be any negative electrode material known to those skilled in the art, and there are no special limitations. In the present invention, it is preferred to be one or more of natural graphite (NG), artificial graphite (AG), hard carbon / soft carbon, silicon carbide (SiC), etc., with SiC being preferred; the negative electrode conductive agent is preferably conductive carbon black (SuperP) and / or carbon nanotubes; the negative electrode binder is preferably polyvinylidene fluoride (PVDF); the mass ratio of the negative electrode material, the negative electrode conductive agent, and the negative electrode binder is preferably (94~96):1:(3~5), more preferably 95:1:4.

[0089] The diaphragm can be any diaphragm known to those skilled in the art, and there are no special restrictions. In this invention, polyethylene (PE), polypropylene (PP), ceramic diaphragm, adhesive-backed diaphragm, etc. are preferred.

[0090] In a specific embodiment of the present invention, the lithium-ion battery includes a solid-state electrode; depending on the type of active material in the solid-state electrode, the solid-state electrode is either a solid-state positive electrode or a solid-state negative electrode; the lithium-ion battery includes a solid-state positive electrode, an electrolyte, a separator, and a negative electrode; the negative electrode and the separator are as described above and will not be repeated here; the electrolyte includes a lithium salt and an organic solvent; the lithium salt and the organic solvent are as described above and will not be repeated here.

[0091] In one specific embodiment of the present invention, the lithium-ion battery includes a positive electrode, an electrolyte, a separator, and a solidified negative electrode sheet; the positive electrode, electrolyte, and separator are as described above, and will not be repeated here.

[0092] In a specific embodiment of the present invention, the lithium-ion battery includes a solidified positive electrode, an electrolyte, a separator, and a solidified negative electrode; the solidified positive electrode, electrolyte, separator, and solidified negative electrode are all as described above, and will not be repeated here.

[0093] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, describes a phosphorus-based crosslinking agent containing silicon ether, a gel polymer electrolyte, a solid-state electrode, and a lithium-ion battery provided by the present invention.

[0094] All reagents used in the following examples are commercially available.

[0095] Example 1

[0096]

[0097] Reaction process:

[0098] A 50 mL three-necked flask was selected, and argon gas was continuously purged into the sealed environment for 30 min. Dimethylvinylsilanol (vinylsilanol) (7.46 g, 0.073 mol), triethylamine (7.37 g, 0.073 mol), and tetrahydrofuran (20 mL) were weighed into the flask. Under an ice-water bath, phosphorus oxychloride (3.98 g, 0.026 mol) was slowly added dropwise to the three-necked flask. After the addition was completed, the mixture was allowed to react at room temperature for 24 h.

[0099] Post-reaction processing:

[0100] The reaction was quenched with water, and solid impurities were removed by filtration. THF was added for extraction, and the mixture was separated three times. The combined organic phase was washed repeatedly with saturated brine to further remove triethylamine hydrochloride. Anhydrous magnesium sulfate was added to the organic phase to remove water. The mixture was then filtered and concentrated by rotary evaporation to obtain a pale yellow liquid. Using pure petroleum ether as the eluent, column chromatography yielded a pale yellow transparent liquid, which was tris(vinyldimethylsilyl)phosphate (6.233 g, yield: 68.5%).

[0101] The tris(vinyldimethylsilyl)phosphate obtained in Example 1 was analyzed using nuclear magnetic resonance (NMR), and its proton NMR spectrum is shown below. Figure 1 As shown.

[0102] Example 2

[0103]

[0104] Reaction process:

[0105] A 50 mL three-necked flask was selected, and argon gas was continuously purged into the sealed environment for 30 min. Dimethylvinylsilanol (vinylsilanol) (7.46 g, 0.073 mol), triethylamine (7.37 g, 0.073 mol), and tetrahydrofuran (20 mL) were weighed into the flask. Under ice-water bath conditions, thiophosphoric chloride (4.4 g, 0.026 mol) was slowly added dropwise to the three-necked flask. After the addition was completed, the mixture was allowed to react at room temperature for 24 h.

[0106] Post-reaction processing:

[0107] The reaction was quenched with water, and solid impurities were removed by filtration. THF was added for extraction, and the mixture was separated three times. The combined organic phase was washed repeatedly with saturated brine to further remove triethylamine hydrochloride. Anhydrous magnesium sulfate was added to the organic phase to remove water. The mixture was then filtered and concentrated by rotary evaporation to obtain a pale yellow liquid. Using pure petroleum ether as the eluent, column chromatography yielded a pale yellow transparent liquid, which was tris(vinyldimethylsilyl)thiophosphate (6.584 g, yield: 69.2%).

[0108] The tris(vinyldimethylsilyl)thiophosphate obtained in Example 2 was analyzed using nuclear magnetic resonance (NMR), and its proton NMR spectrum is shown below. Figure 2 As shown.

[0109] Example 3

[0110]

[0111] Reaction process:

[0112] A 50 mL three-necked flask was selected, and argon gas was continuously purged into the sealed environment for 30 min. Dimethylvinylsilanol (vinylsilanol) (7.46 g, 0.073 mol), triethylamine (7.37 g, 0.073 mol), and tetrahydrofuran (20 mL) were weighed into the flask. Under an ice-water bath, phosphorus trichloride (3.57 g, 0.026 mol) was slowly added dropwise to the three-necked flask. After the addition was completed, the mixture was allowed to react at room temperature for 24 h.

[0113] Post-reaction processing:

[0114] The reaction was quenched with water, and solid impurities were removed by filtration. THF was added for extraction, and the mixture was separated three times. The combined organic phase was washed repeatedly with saturated brine to further remove triethylamine hydrochloride. Anhydrous magnesium sulfate was added to the organic phase to remove water. The mixture was then filtered and concentrated by rotary evaporation to obtain a pale yellow liquid. Using pure petroleum ether as the eluent, column chromatography yielded a pale yellow transparent liquid, which was tris(vinyldimethylsilyl)phosphite (6.326 g, yield: 72.8%).

[0115] The tris(vinyldimethylsilyl)phosphite obtained in Example 3 was analyzed using nuclear magnetic resonance (NMR), and its proton NMR spectrum is shown below. Figure 3 As shown.

[0116] Example 4

[0117] PVDF was dissolved in NMP at a ratio of 5% beforehand. For the positive electrode, NCM811, SP, and PVDF were mixed in a mass ratio of 90:5:5. The stirring tank was set to 2000 rpm and stirred for 25 min. The positive electrode slurry was then evenly coated onto aluminum foil. The coated positive electrode sheet was placed in a 90℃ oven and stored for 4 h. Afterward, it was rolled using a roller press to obtain the positive electrode sheet with an areal density of 0.135 mg / mm². 2 Compacted density 3.0 g / cm³ 3 .

[0118] The negative electrode was prepared by mixing SiC, SP, and PVDF in a mass ratio of 95:1:4. The stirring tank was set to a speed of 2000 rpm and stirred for 25 minutes. The negative electrode slurry was then uniformly coated onto copper foil. The coated negative electrode sheet was placed in a 90℃ oven and stored for 4 hours. Finally, it was rolled using a roller press to obtain the negative electrode sheet with an areal density of 0.072 mg / mm². 2 Compacted density 1.6 g / cm³ 3 .

[0119] PP diaphragms are used to separate the positive and negative electrode plates.

[0120] 1 M lithium hexafluorophosphate was dissolved in a mixture of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 2:3. Methyl methacrylate and tris(vinyldimethylsilyl)phosphite were added sequentially to the mixture in a ratio of 7:3, totaling 13% wt, followed by the addition of AIBN at a monomer content of 2% wt. The resulting liquid was stirred at room temperature until a clear, homogeneous phase was obtained, yielding the electrolyte precursor solution.

[0121] The obtained positive electrode, negative electrode, separator, and electrolyte precursor solution were assembled into a pouch cell. The assembled cell was placed in a 60°C incubator for 12 hours to initiate in-situ polymerization, thus obtaining the cell to be tested.

[0122] Example 5

[0123] PVDF was dissolved in NMP at a ratio of 5% beforehand. For the positive electrode, NCM811, SP, and PVDF were mixed in a mass ratio of 90:5:5. The stirring tank was set to 2000 rpm and stirred for 25 min. The positive electrode slurry was then evenly coated onto aluminum foil. The coated positive electrode sheet was placed in a 90℃ oven and stored for 4 h. Afterward, it was rolled using a roller press to obtain the positive electrode sheet with an areal density of 0.135 mg / mm². 2 Compacted density 3.0 g / cm³ 3 .

[0124] The negative electrode was prepared by mixing SiC, SP, and PVDF in a mass ratio of 95:1:4. The stirring tank was set to a speed of 2000 rpm and stirred for 25 minutes. The negative electrode slurry was then uniformly coated onto copper foil. The coated negative electrode sheet was placed in a 90℃ oven and stored for 4 hours. Finally, it was rolled using a roller press to obtain the negative electrode sheet with an areal density of 0.072 mg / mm². 2 Compacted density 1.6 g / cm³ 3 .

[0125] PP diaphragms are used to separate the positive and negative electrode plates.

[0126] 1 M lithium hexafluorophosphate was dissolved in a mixture of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 2:3. Methyl methacrylate and tris(vinyldimethylsilyl)thiophosphate were added sequentially to the mixture in a ratio of 7:3, totaling 13% wt, followed by the addition of AIBN at a monomer content of 2% wt. The resulting liquid was stirred at room temperature until a clear, homogeneous phase was obtained, yielding the electrolyte precursor solution.

[0127] The obtained positive electrode, negative electrode, separator, and electrolyte precursor solution were assembled into a pouch cell. The assembled cell was placed in a 60°C incubator for 12 hours to initiate in-situ polymerization, thus obtaining the cell to be tested.

[0128] Example 6

[0129] PVDF was dissolved in NMP at a ratio of 5% beforehand. For the positive electrode, NCM811, SP, and PVDF were mixed in a mass ratio of 90:5:5. The stirring tank was set to 2000 rpm and stirred for 25 min. The positive electrode slurry was then evenly coated onto aluminum foil. The coated positive electrode sheet was placed in a 90℃ oven and stored for 4 h. Afterward, it was rolled using a roller press to obtain the positive electrode sheet with an areal density of 0.135 mg / mm². 2 Compacted density 3.0 g / cm³ 3 .

[0130] The negative electrode was prepared by mixing SiC, SP, and PVDF in a mass ratio of 95:1:4. The stirring tank was set to a speed of 2000 rpm and stirred for 25 minutes. The negative electrode slurry was then uniformly coated onto copper foil. The coated negative electrode sheet was placed in a 90℃ oven and stored for 4 hours. Finally, it was rolled using a roller press to obtain the negative electrode sheet with an areal density of 0.072 mg / mm². 2 Compacted density 1.6 g / cm³ 3 .

[0131] PP diaphragms are used to separate the positive and negative electrode plates.

[0132] 1 M lithium hexafluorophosphate was dissolved in a mixture of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 2:3. Methyl methacrylate and tris(vinyldimethylsilyl)phosphate were added sequentially to the mixture in a ratio of 7:3, totaling 13% wt, followed by the addition of AIBN at a monomer content of 2% wt. The resulting liquid was stirred at room temperature until a clear, homogeneous phase was obtained, yielding the electrolyte precursor solution.

[0133] The obtained positive electrode, negative electrode, separator, and electrolyte precursor solution were assembled into a pouch cell. The assembled cell was placed in a 60°C oven for 12 hours to initiate in-situ polymerization, thus obtaining the cell to be tested.

[0134] Comparative Example 1

[0135] PVDF was dissolved in NMP at a ratio of 5% beforehand. For the positive electrode, NCM811, SP, and PVDF were mixed in a mass ratio of 90:5:5. The stirring tank was set to 2000 rpm and stirred for 25 min. The positive electrode slurry was then evenly coated onto aluminum foil. The coated positive electrode sheet was placed in a 90℃ oven and stored for 4 h. Afterward, it was rolled using a roller press to obtain the positive electrode sheet with an areal density of 0.135 mg / mm². 2 Compacted density 3.0 g / cm³ 3 .

[0136] The negative electrode was prepared by mixing SiC, SP, and PVDF in a mass ratio of 95:1:4. The stirring tank was set to a speed of 2000 rpm and stirred for 25 minutes. The negative electrode slurry was then uniformly coated onto copper foil. The coated negative electrode sheet was placed in a 90℃ oven and stored for 4 hours. Finally, it was rolled using a roller press to obtain the negative electrode sheet with an areal density of 0.072 mg / mm². 2 Compacted density 1.6 g / cm³ 3 .

[0137] PP diaphragms are used to separate the positive and negative electrode plates.

[0138] 1 M lithium hexafluorophosphate was dissolved in a mixture of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 2:3. Methyl methacrylate (13% wt) was added to the mixture. Then, AIBN (2% wt of monomer) was added. The resulting liquid was stirred at room temperature until a clear, homogeneous phase was obtained, yielding the electrolyte precursor solution.

[0139] The obtained positive electrode, negative electrode, separator, and electrolyte precursor solution were assembled into a pouch cell. The assembled cell was placed in a 60°C oven for 12 hours to initiate in-situ polymerization, thus obtaining the cell to be tested.

[0140] Comparative Example 2

[0141] PVDF was dissolved in NMP at a ratio of 5% beforehand. For the positive electrode, NCM811, SP, and PVDF were mixed in a mass ratio of 90:5:5. The stirring tank was set to 2000 rpm and stirred for 25 min. The positive electrode slurry was then evenly coated onto aluminum foil. The coated positive electrode sheet was placed in a 90℃ oven and stored for 4 h. Afterward, it was rolled using a roller press to obtain the positive electrode sheet with an areal density of 0.135 mg / mm². 2 Compacted density 3.0 g / cm³ 3 .

[0142] The negative electrode was prepared by mixing SiC, SP, and PVDF in a mass ratio of 95:1:4. The stirring tank was set to a speed of 2000 rpm and stirred for 25 minutes. The negative electrode slurry was then uniformly coated onto copper foil. The coated negative electrode sheet was placed in a 90℃ oven and stored for 4 hours. Finally, it was rolled using a roller press to obtain the negative electrode sheet with an areal density of 0.072 mg / mm². 2 Compacted density 1.6 g / cm³ 3 .

[0143] PP diaphragms are used to separate the positive and negative electrode plates.

[0144] 1 M lithium hexafluorophosphate was dissolved in a mixture of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 2:3. Tris(vinylmethylsilyl)phosphite was added to the mixture at a concentration of 5% wt. The resulting liquid was stirred at room temperature until a clear, homogeneous phase was obtained, which was the electrolyte.

[0145] The positive electrode, negative electrode, separator, and electrolyte obtained above are assembled into a pouch cell to obtain the battery to be tested.

[0146] The electrolytes from Examples 4, 5, 6, Comparative Example 1, and Comparative Example 2 were assembled into Kelude CR2032 button cells, and their electrochemical performance was tested. Specifically, the button cells assembled with the electrolyte precursor solutions from Examples 4, 5, 6, and Comparative Example 1 were each placed in a 60°C incubator for 12 hours to initiate in-situ polymerization before testing. The button cell assembled with the electrolyte from Comparative Example 2 could be tested directly.

[0147] Detection method:

[0148] Using an electrochemical workstation, linear sweep voltammetry (LSV) was employed to test the electrochemical window with a voltage range of 2–6 V, a voltage scan rate of 1 mV / s, and a sampling interval of 0.1 s. The results are shown in Table 1.

[0149] Electrochemical impedance spectroscopy (EIS) was used to measure the ionic conductivity by setting an AC voltage perturbation of 5mV / 10mV, a frequency test range of 100000~0.01Hz, and a sampling interval of 2s. The results are shown in Table 1.

[0150] The steady-state current method (it) was used. The test voltage was 0.01V, the test time was 3000s, and the sampling interval was 0.1s. EIS tests were performed before and after it to obtain the interfacial impedance and the ion transference number. The results are shown in Table 1.

[0151] Further, the cycle performance was evaluated by fabricating a pouch cell, and the cycle performance results are as follows: Figure 1 As shown in Table 2, the thermal runaway results obtained from the hot box test of the pouch battery are shown in Table 2.

[0152] Cyclic testing standard: The charge and discharge process is conducted in a constant temperature chamber at an ambient temperature of 25℃±2℃, with a charge / discharge rate of 1C and a voltage range of 2.75~4.2V. Capacity calibration is required before cycling: First, discharge at 1C to the termination voltage of 2.75V and rest for 10 minutes; then charge at 1C to the termination voltage of 4.2V. Once the termination voltage is reached, switch to constant voltage charging at 4.2V until the current is less than or equal to the given cutoff current of 0.05C, and rest for 10 minutes; then discharge at 1C to the termination voltage of 2.75V and rest for 10 minutes. After three such calibrated capacity cycles, the cell is subjected to a 25℃ cyclic test.

[0153] Thermal runaway test: After fully charging the test cell at a 1C rate, it is left to stand for 1 hour. Its OCV and internal resistance are measured, and then it is placed in a test chamber. The chamber is heated to 150℃±2℃ at a rate of 5℃ / min, held for 30 minutes, and then stopped. It is then left to stand for another 1 hour, and its OCV and internal resistance are measured again. The passing standard is no fire or explosion. If no explosion or fire occurs, the temperature is increased (in 10℃ increments) until fire or explosion occurs.

[0154] Depend on Figure 4 The results showed that the crosslinking agent prepared in Example 4 enabled the pouch cell to retain 95% of its capacity after 300 cycles. Since both trivalent and pentavalent phosphorus have certain flame-retardant effects, the safety performance of the electrolyte was further tested, and its thermal runaway temperature was 190°C.

[0155] Table 1. Electrochemical window, lithium-ion conductivity, and lithium-ion transport number test results of the electrolyte.

[0156]

[0157] Table 2. Results of thermal chamber test for pouch batteries

[0158]

[0159] From Table 1, Table 2 and Figure 4 It is evident that the gel polymer electrolyte prepared using the crosslinking agent prepared in Example 4 exhibits superior electrochemical performance. When tris(vinyldimethylsilyl)phosphite is used as a crosslinking agent in the gel polymer electrolyte, its electrochemical performance is significantly improved compared to gel polymer electrolytes without this crosslinking agent, and also when this crosslinking agent is used as an additive.

[0160] The pouch cells prepared in Example 4, Comparative Example 1, and Comparative Example 2 were subjected to a full-charge high-temperature storage test (60°C), and the results are shown in Table 3. Figure 3 It can be seen that the soft-pack batteries prepared in Comparative Examples 1 and 2 showed peeling after 72 and 54 days, respectively, while the soft-pack battery cell prepared in Example 4 had better hardness and no obvious gas generation. This indicates that the silicon-oxygen bonds contained in the crosslinking agent can effectively remove HF and suppress the gas generation phenomenon of the battery.

[0161] Table 3. Test results of fully charged soft-pack batteries in a heated chamber.

[0162]

[0163] Example 7

[0164] PVDF was pre-dissolved in NMP at a ratio of 5%. The positive electrode was prepared by weighing NCM811, SP, and PVDF in a 90:5:5 mass ratio and placing them in a stirred tank. Then, a mixture of 3 wt% methyl methacrylate and tris(vinylmethylsilyl)phosphite (mass ratio 6:4) was added, along with 1 wt% AIBN of monomers. The stirred tank was set to 2000 rpm and stirred for 25 min. The positive electrode slurry was then uniformly coated onto aluminum foil. The coated positive electrode sheet was first placed in a 45°C oven for 45 min to initiate monomer polymerization. Then, the electrode sheet was placed in a 90°C oven for 4 h. Finally, it was rolled using a roller press to obtain a solidified positive electrode sheet with an areal density of 0.135 mg / mm². 2 Compacted density 3.0 g / cm³ 3 .

[0165] The negative electrode was prepared by mixing SiC, SP, and PVDF in a mass ratio of 95:1:4. The stirring tank was set to a speed of 2000 rpm and stirred for 25 minutes. The negative electrode slurry was then uniformly coated onto copper foil. The coated negative electrode sheet was placed in a 90℃ oven and stored for 4 hours. Finally, it was rolled using a roller press to obtain the negative electrode sheet with an areal density of 0.072 mg / mm². 2 Compacted density 1.6 g / cm³ 3 .

[0166] PP diaphragms are used to separate the positive and negative electrode plates.

[0167] 1 M lithium hexafluorophosphate was dissolved in a mixture of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 2:3. The resulting liquid was stirred at room temperature until a transparent, homogeneous liquid was obtained, which yielded the electrolyte.

[0168] The positive electrode, negative electrode, separator, and electrolyte obtained above are assembled into a pouch cell to obtain the battery to be tested.

[0169] Comparative Example 3

[0170] PVDF was dissolved in NMP at a ratio of 5% beforehand. For the positive electrode, NCM811, SP, and PVDF were weighed in a 90:5:5 mass ratio and placed in a mixing tank. The mixing speed was set to 2000 rpm for 25 min. The positive electrode slurry was then evenly coated onto aluminum foil. The electrode sheet was then placed in a 90℃ oven and stored for 4 h. Finally, it was rolled using a roller press to obtain the positive electrode sheet with an areal density of 0.135 mg / mm². 2 Compacted density 3.0 g / cm³ 3 .

[0171] The negative electrode was prepared by mixing SiC, SP, and PVDF in a mass ratio of 95:1:4. The stirring tank was set to a speed of 2000 rpm and stirred for 25 minutes. The negative electrode slurry was then uniformly coated onto copper foil. The coated negative electrode sheet was placed in a 90℃ oven and stored for 4 hours. Finally, it was rolled using a roller press to obtain the negative electrode sheet with an areal density of 0.072 mg / mm². 2 Compacted density 1.6 g / cm³ 3 .

[0172] PP diaphragms are used to separate the positive and negative electrode plates.

[0173] 1 M lithium hexafluorophosphate was dissolved in a mixture of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 2:3. The resulting liquid was stirred at room temperature until a transparent, homogeneous liquid was obtained, which yielded the electrolyte.

[0174] The positive electrode, negative electrode, separator, and electrolyte obtained above are assembled into a pouch cell to obtain the battery to be tested.

[0175] The electrochemical performance of the pouch cells obtained in Example 7 and Comparative Example 3 was tested, and the results are shown in Table 4.

[0176] Cyclic testing standard: The charge and discharge process is conducted in a constant temperature chamber at an ambient temperature of 25℃±2℃, with a charge / discharge rate of 1C and a voltage range of 2.75~4.2V. Capacity calibration is required before cycling: First, discharge at 1C to the termination voltage of 2.75V and rest for 10 minutes; then charge at 1C to the termination voltage of 4.2V. Once the termination voltage is reached, switch to constant voltage charging at 4.2V until the current is less than or equal to the given cutoff current of 0.05C, and rest for 10 minutes; then discharge at 1C to the termination voltage of 2.75V and rest for 10 minutes. After three such calibrated capacity cycles, the cell is subjected to a 25℃ cyclic test.

[0177] Thermal runaway test: After fully charging the test cell at a 1C rate, it is left to stand for 1 hour. Its OCV and internal resistance are measured, and then it is placed in a test chamber. The chamber is heated to 150℃±2℃ at a rate of 5℃ / min, held for 30 minutes, and then stopped. It is then left to stand for another 1 hour, and its OCV and internal resistance are measured again. The passing standard is no fire or explosion. If no explosion or fire occurs, the temperature is increased (in 10℃ increments) until fire or explosion occurs.

[0178] Table 4. Electrical performance data of the pouch cells in Example 7 and Comparative Example 3

[0179]

[0180] The data above shows that when tris(vinyldimethylsilyl)phosphite is used as a crosslinking agent for the solidification of the positive electrode, although the impedance increases, the thermal runaway temperature and capacity retention rate are both improved. This indicates that it can effectively remove singlet oxygen generated during charging, which helps to improve the cycle stability of the battery. Furthermore, the thermal runaway temperature indicates that the solidification of the electrode improves its safety. The electrode solidification initiation method is not limited to thermal initiation, but also includes photoinitiation. The electrode solidification is not limited to being added only to the positive electrode slurry, but also includes the negative electrode slurry. The electrode solidification method is not limited to adding in-situ solidified electrolyte during the homogenization stage, but includes coating the electrode / separator surface with in-situ solidified electrolyte during the coating stage to form a fully solid structure on the porous electrode / separator surface; and includes electrode solidification methods that immerse the electrode / separator in in-situ solidified electrolyte to allow the polymer solidified electrolyte to fully penetrate between the electrode particles.

[0181] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A phosphorus-based crosslinking agent containing a silicon ether, characterized by, having a structure represented by Formula (I) or Formula (II): Formula (I); Formula (II); wherein R1 and R2 are each independently selected from substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C2-C10 alkenyl, and substituted or unsubstituted C6-C10 aryl; R3 is selected from substituted or unsubstituted C2-C10 alkenyl; the substituents in the substituted C1-C10 alkyl, substituted C2-C10 alkenyl, and substituted C6-C10 aryl are each independently selected from one or more of C1-C10 alkyl, C2-C10 alkenyl, and C6-C10 aryl; A is selected from O or S.

2. The silicon-ether-containing phosphorus-based crosslinker according to claim 1, characterized in that, having a structure represented by Formula (III) or Formula (IV): Formula (III); Formula (IV).

3. The silicon-ether-containing phosphorus-based crosslinking agent according to claim 1 or 2, characterized by R1 and R2 are each independently selected from substituted or unsubstituted C1-C3 alkyl, substituted or unsubstituted C2-C3 alkenyl, and substituted or unsubstituted C6-C10 aryl; the substituents in the substituted C1-C3 alkyl, substituted C2-C3 alkenyl, and substituted C6-C10 aryl are each independently selected from one or more of C1-C3 alkyl, C2-C3 alkenyl, and C6-C10 aryl.

4. The silicon-ether-containing phosphorus-based crosslinker according to claim 3, wherein R1 and R2 are methyl.

5. A gel polymer electrolyte, characterized by, formed from an electrolyte precursor solution; the electrolyte precursor solution comprises the silicon-ether-containing phosphorus-based crosslinking agent of any one of claims 1-4, an acrylate monomer, a lithium salt, an organic solvent, and an initiator.

6. The gel polymer electrolyte according to claim 5, wherein the total mass of the silicon-ether-containing phosphorus-based crosslinking agent and the acrylate monomer is 3%-20% of the mass of the electrolyte precursor solution; and the mass ratio of the silicon-ether-containing phosphorus-based crosslinking agent to the acrylate monomer is (1-4):(6-9).

7. The gel polymer electrolyte according to claim 5, wherein the mass of the lithium salt is 5%-20% of the mass of the electrolyte precursor solution; and / or, the mass of the initiator is 0.1%-5% of the total mass of the silicon-ether-containing phosphorus-based crosslinking agent and the acrylate monomer; and / or, the acrylate monomer is selected from one or more of methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate; and / or, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(fluorosulfonyl)imide; and / or, the organic solvent is selected from one or more of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate; and / or, the initiator is selected from azobisisobutyronitrile and / or azobisisoheptyl nitrile.

8. A solidified electrode, characterized by, comprising a current collector and a modified active layer attached to at least one surface of the current collector; the modified active layer comprises a crosslinked polymer and an active material; the raw materials for forming the crosslinked polymer comprise the silicon-ether-containing phosphorus-based crosslinking agent of any one of claims 1-4 and the acrylate monomer; and the active material is selected from a positive electrode material or a negative electrode material.

9. The solidified electrode of claim 8, wherein, the mass of the crosslinked polymer is 0.1%-15% of the mass of the modified active layer; and / or, the mass ratio of the silicon-ether-containing phosphorus-based crosslinking agent to the acrylate monomer is (1-4):(6-9).

10. A lithium-ion battery, characterized by, The gel polymer electrolyte according to any one of claims 5 to 7 and / or the solidified electrode sheet according to claim 8 or 9.

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