Silane-modified polyether polyol copolymer solid polymer electrolyte and preparation method thereof

Abstract

The present invention relates to a silane-modified polyether polyol copolymer solid polymer electrolyte and a preparation method thereof. The solid polymer electrolyte comprises: (1) a silane-modified polyether polyol copolymer; (2) a lithium-containing electrolyte compound; (3) an optional crosslinking agent; and (4) an optional catalyst. In the present invention, the silane-modified polyether polyol copolymer solid polymer electrolyte exhibits good electrochemical stability, an electrochemical window greater than 4.5 V, and a room temperature ionic conductivity of 1×10 ‑5 S / cm‑1×10 ‑3 Furthermore, the cross-linked silicon-oxygen network structure formed in the solid polymer electrolyte of the present invention can produce a homogeneous membrane with good mechanical properties, and its mechanical strength is 0.5MPa-300MPa.

Description

Technical Field

[0001] The invention relates to a silane-modified polyether polyol copolymer solid polymer electrolyte and a preparation method thereof. Technical Background

[0002] Lithium-ion batteries, with their advantages of high energy density and output voltage, no memory effect, and environmental friendliness, have been widely used in electronics, aerospace, electric vehicles, and other fields. As one of the key materials, the structure and properties of lithium-ion battery electrolytes play a crucial role in improving the rate performance and thermal stability of lithium-ion batteries. They largely determine the battery's power density, cycle stability, safety, high and low temperature performance, and service life.

[0003] Traditional lithium-ion batteries typically use liquid electrolytes and polyolefin separators, such as polyethylene (PE) and polypropylene (PP). Although liquid polyelectrolytes exhibit high ionic conductivity, effectively wet the electrodes and form a stable solid electrolyte interface (SEI) film on the electrode surface, liquid electrolytes contain large amounts of flammable and volatile organic solvents. When the battery is used improperly or a short circuit occurs within the battery, heat buildup can cause the electrolyte to volatilize, leading to leakage and potentially causing safety accidents.

[0004] All-solid-state polymer electrolyte (ASPE) batteries use polymer electrolytes instead of traditional liquid electrolytes, and do not contain organic solvents. They offer advantages such as good safety, high energy density, a wide operating temperature range, and long cycle life, making them a research hotspot in the lithium-ion battery field. Currently, several ASPE systems that have been widely studied include polyethylene oxide (PEO)-based systems, polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polycarbonate (PC), and polysiloxane (PS).

[0005] Among them, PEO-based ASPEs are the earliest and most extensively studied class of ASPEs. However, these electrolytes suffer from low room-temperature ionic conductivity and a narrow electrochemical window. Electrolytes composed of PAN, PMMA, PVDF, or PVC with lithium salts typically require plasticization with an organic electrolyte to form gel polyelectrolytes, which are not fully solid-state polyelectrolytes. Polycarbonate (PC)-based fully solid-state polyelectrolytes contain highly polar carbonate groups and are amorphous at room temperature, which facilitates the dissociation of lithium salts. This reduces the interaction between anions and cations in the lithium salt, inhibits ion aggregation, and increases the free lithium ion concentration, thereby improving the electrolyte's ionic conductivity and ion transference number. However, these materials suffer from poor film-forming properties and low mechanical strength. The Si-O-Si bonds in polysiloxane have a low bond rotation potential energy (0.8 kJ / mol), resulting in strong molecular chain segment mobility and the tendency to form an amorphous structure. Furthermore, these electrolytes offer advantages such as a high electrochemical window, excellent thermal stability, and environmental friendliness.

[0006] In 1986, Brocq et al. first introduced polysiloxane side chains into oligoethylene oxide (PEO), and the resulting composite electrolyte showed higher room temperature ionic conductivity (σ≈10 -5 S / cm), but the polymer has the problem of easy hydrolysis of the side chain and poor stability. CN103208651A discloses a lithium-conducting siloxane polyelectrolyte with a room temperature lithium ion conductivity of 2×10 -5 -1×10 -4 CN106785032B mixes a silane-terminated polyether prepolymer with a conductive lithium salt electrolyte and uses an organic solvent as a plasticizer to prepare a gel solid polyelectrolyte on a non-woven fabric support with an ionic conductivity of 10 at 25°C. -4 Scm -1 Furthermore, CN108899579A combines inorganic nanoparticles or organic polymer materials with acidic and alkaline properties with end-silane-terminated polyethers and forms a self-crosslinking composite solid electrolyte with conductive lithium salts. The composite electrolyte has small shrinkage and deformation, and the ionic conductivity is 10 at 25°C. -4 Scm -1 , and the electrochemical window is greater than 5V, with strong electrochemical stability. CN108242563A reported that the solution formed by mixing alkylsilane polymer with lithium salt and additives was scraped onto a porous support material and dried at 60-80°C to prepare an alkylsilane polymer electrolyte with a mechanical strength of 0.5MPa-300MPa; its electrochemical window is greater than 4.3V, and it has good compatibility with high-voltage positive electrode materials. The room temperature ionic conductivity is 1×10 -5 S / cm-10 -3S / cm, the assembled battery has excellent long cycle performance. JPH08026162B2 compares the performance of polysiloxanes with different heteroatom side chain substitutions. At 20℃, its ionic conductivity is 10 -6 -10 -4 S / cm. KR101998119B1 discloses a polymer obtained by reacting a diol and 3-(triethoxysilyl)propyl isocyanate, and compares its room temperature conductivity at different LiTFSI salt concentrations. KR101995836B1 also discloses a polymer obtained by reacting a diol and 3-(triethoxysilyl)propyl isocyanate, and compares its room temperature conductivity at different LiTFSI salt concentrations. KR102026682B1 further discloses a polymer electrolyte obtained by reacting 2-(2-methoxyethoxy)ethanol, 3-(triethoxysilyl)propyl isocyanate and a diol or carbonate diol.

[0007] In the existing technology, all-solid-state polymer electrolytes have superior inherent advantages and huge application prospects. However, most of the siloxane-based all-solid-state polymer electrolytes reported so far have poor film-forming properties and low mechanical strength of homogeneous films. Most of them are composited on porous supports. In addition, the catalysts used in the preparation of siloxane-based all-solid-state polymer electrolytes in the existing technology are mostly organotin catalysts, which are harmful to human health and the environment. With the increasing environmental protection requirements of the European Union, their use is gradually restricted. Therefore, there is still a need for a new type of polymer electrolyte with good electrochemical stability, film-forming properties, and membrane mechanical strength. Summary of the Invention

[0008] The purpose of the exemplary embodiments of the present invention is to address the above-mentioned and other deficiencies in the prior art and to provide a high-performance silane-modified polyether polyol copolymer solid polymer electrolyte and a preparation method thereof.

[0009] In one aspect, the present invention provides a solid polymer electrolyte comprising:

[0010] (1) Silane-modified polyether polyol copolymers;

[0011] (2) lithium-containing electrolyte compounds;

[0012] (3) optionally a cross-linking agent; and

[0013] (4) Optional catalyst.

[0014] In some embodiments of the present invention, based on the weight of the solid polymer electrolyte, the silane-modified polyether polyol copolymer is 10-65 weight %; the lithium-containing electrolyte compound is 5-90 weight %; the cross-linking agent is 0-10 weight %; and the catalyst is 0-15 weight %.

[0015] In some embodiments of the present invention, the weight average molecular weight of the silane-modified polyether polyol copolymer is 1,000-45,000.

[0016] In some embodiments of the present invention, the silane-modified polyether polyol copolymer is a polyether polyol copolymer modified with a silane containing a carbamate group.

[0017] In some embodiments of the present invention, the silane-modified polyether polyol copolymer has the general formula (I):

[0018]

[0019] In the formula, R1 is a C1-C5 alkane group, a C1-C5 olefin group or a C1-C5 alkoxy group; R2 is a C1-C10 alkane group; or a combination of any two or three thereof; wherein n is an integer selected from 1-50, and m, k and x are integers selected from 1-1000.

[0020] In some embodiments of the present invention, the lithium-containing electrolyte compound includes lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium difluorophosphate, lithium tetrafluoroborate, lithium bis(oxalatoborate) (LiBOB), lithium difluorooxalatoborate (LiDFOB), lithium trifluoromethanesulfonate (CF3SO3Li), lithium bis(trifluoromethanesulfonyl imide) (LiTFSI), lithium bis(fluorosulfonyl imide) (LiFSI), or any combination thereof.

[0021] In some embodiments of the present invention, the cross-linking agent is selected from silane coupling agents, silicate compounds and combinations thereof; preferably, it is selected from N-n-butyl-3-aminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyldimethoxysilane, diethylaminomethyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, methyl orthosilicate, ethyl orthosilicate, butyl orthosilicate and combinations thereof.

[0022] In some embodiments of the present invention, the catalyst is an organic bismuth catalyst; preferably, the catalyst is selected from bismuth (tris (2-ethylhexanoate), bismuth trioctanoate, bismuth neodecanoate, bismuth isooctanoate, bismuth laurate, bismuth cyclohexanoate, bismuth carboxylate and combinations thereof.

[0023] On the other hand, the present invention also provides a method for preparing a solid polymer electrolyte, the method comprising:

[0024] (1) dissolving a lithium-containing electrolyte compound in an organic solvent to form a lithium salt solution;

[0025] (2) adding the silane-modified polyether polyol copolymer to the lithium salt solution and stirring under sealed conditions for 1-24 hours;

[0026] (3) optionally adding a cross-linking agent and / or a catalyst and continuing to stir under sealed conditions; and

[0027] (4) forming a film at a relative humidity of 5.0-95.0% and drying at a temperature of 10-80° C. to obtain a solid polymer electrolyte comprising a silane-modified polyether polyol copolymer.

[0028] In some embodiments of the present invention, the organic solvent is selected from a combination of one or more of C1-C5 alcohols, C1-C5 nitriles, C1-C3 chloroalkanes, aliphatic N-alkyl substituted amides, and C2-C6 carbonates; preferably, the organic solvent is selected from one or more of methanol, ethanol, ethylene glycol, acetonitrile, chloroform, N-methylpyrrolidone, N,N-dimethylformamide and N,N-dimethylacetamide, dimethyl sulfoxide, dimethyl carbonate, ethylene carbonate, and propylene carbonate.

[0029] In the present invention, the silane-modified polyether polyol copolymer can be cross-linked to form a silicon-oxygen network structure, does not require a porous support, and can be directly formed into a film. The resulting homogeneous film has good mechanical properties and a mechanical strength of 0.5 MPa to 300 MPa. Preferably, the present invention uses a silane-modified polyether polyol copolymer containing a carbamate group (-NHCOO-) to prepare a solid polyelectrolyte membrane, wherein the -NHCOO- has a high dielectric constant and polarization density and can form more hydrogen bonds in the polymer solid electrolyte membrane, so that the prepared silane-modified polyether polyol copolymer solid polymer electrolyte shows good electrochemical stability, its electrochemical window is greater than 4.5 V, and the room temperature ionic conductivity is 1×10 -5 S / cm-1×10 - 3 S / cm, even greater than 4×10 -5 S / cm up to 1×10 -3 S / cm, far exceeding the ionic conductivity of conventional solid polymer electrolytes in the prior art. Furthermore, the organobismuth catalyst employed in this invention is highly efficient and environmentally friendly, replacing the organotin catalysts used in existing electrolyte technologies. It offers advantages such as low cost, excellent hydrolytic stability, low toxicity, and low radioactivity.

[0030] The above features and other features, aspects and advantages of the present invention will be apparent from the following detailed description. The present invention includes any combination of two, three, four or more of the above-described embodiments, as well as any combination of any two, three, four or more features or elements described herein, regardless of whether these features or elements are explicitly combined in the specific embodiments described herein. This document is intended to be read as a whole, and any separable features or elements of the invention disclosed herein in any of its various aspects and embodiments should be considered to be intended to be combinable features or elements unless the context clearly states otherwise. Other aspects and advantages of the present invention will become apparent from the following. DETAILED DESCRIPTION

[0031] The present invention is described more fully hereinafter with reference to exemplary embodiments thereof. These exemplary embodiments are described so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements.

[0032] As used herein, the terms "C1-C5 alkane" and "C1-C10 alkane" refer to an alkane group having 1 to 5 carbon atoms (C1-C5) and an alkane group having 1 to 10 carbon atoms (C1-C10), respectively. For example, the "C1-C5 alkane" includes methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, etc. The "C1-C10 alkane" includes methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl, heptyl, octyl, nonyl, decyl, etc.

[0033] As used herein, the term "C2-C5 alkene group" refers to an alkene group having 2 to 5 carbon atoms (C2-C5). For example, the "C2-C5 alkene group" may include ethenyl, propenyl, butenyl, pentenyl, and the like.

[0034] Herein, the term "C1-C5 alkoxy" refers to an alkoxy group having 1 to 5 carbon atoms (C1-C5). For example, the "C1-C5 alkoxy" includes methoxy, ethoxy, propoxy, butoxy, pentoxy, etc.

[0035] As used herein, the term "polyether polyol" refers to an oligomer having an ether bond (-R-O-R-, wherein R is an alkane group or an aromatic hydrocarbon group) in its main chain and having more than two hydroxyl groups (-OH) in its terminal or side groups.

[0036] As used herein, the term "weight average molecular weight" refers to the sum of the weight fractions of molecules of different molecular weights multiplied by their corresponding molecular weights. In the present invention, the weight average molecular weight is calculated as follows:

[0037]

[0038] Where M w is the weight average molecular weight, m i is the molecular mass, M i is the relative molecular mass, n i Is with M i The number of molecules in the mass, w i is the quality score.

[0039] Generally, methods for determining the weight average molecular weight include light scattering, ultracentrifugal sedimentation velocity, and gel chromatography.

[0040] Silane-modified polyether polyol copolymers

[0041] In the present invention, the silane-modified polyether polyol copolymer can be a commercially available copolymer or a copolymer prepared by modifying a polyether polyol with a functional silane. For example, the silane-modified polyether polyol copolymer of the present invention can be purchased from the Funpoly series of products of Suzhou Hantuo Material Technology Co., Ltd.

[0042] In the present invention, the weight average molecular weight of the silane-modified polyether polyol copolymer may be 1000-45000, 1000-40000, 1000-35000, 1000-30000, 1000-25000, 1000-20000, 1000-15000, 1000-10000, 1000-5000, 1000-3000, 3000-45000, 3000-40000, 3000-350 00, 3000-30000, 3000-25000, 3000-20000, 3000-15000, 3000-10000, 3000-5000, 5000-45000, 5000-40000, 5000-35000, 5000-30000, 5000-25000, 5000-20000, 5000-15000, 5000-10000, 1000-45000, 10,000-40,000, 10,000-35,000, 10,000-30,000, 10,000-25,000, 10,000-20,000, 10,000-15,000, 15,000-45,000, 15,000-40,000, 15,000-35,000, 15,000-30,000, 15,000-25,000, 15,000-20,000, 20,000-45,000, 20,000-40,000 , 20000-35000, 20000-30000, 20000-25000, 25000-45000, 25000-40000, 25000-35000, 25000-30000, 30000-45000, 30000-40000, 30000-35000, 35000-45000, 35000-40000, 40000-45000 or any value within the above range. In the present invention, if the weight average molecular weight of the silane-modified polyether polyol copolymer is lower than 1000, the film-forming property of the obtained solid polyelectrolyte is poor; if the weight average molecular weight of the silane-modified polyether polyol copolymer is higher than 45000, the silane-modified polyether polyol copolymer is not easily soluble, which increases the process complexity and operation difficulty.

[0043] In a specific embodiment, a polyether polyol copolymer is modified with a functional silane, such as a silane containing a carbamate group (-NHCOO-). The silane containing a carbamate group (-NHCOO-) (or a silane containing an isocyanate group) can react with a polyether polyol containing a hydroxyl group, that is, the silane group is grafted onto the structure of the polyether polyol through the reaction of the NCO group with the hydroxyl group. The carbamate group has a high dielectric constant and polarization density, and can form more hydrogen bonds in the polymer solid electrolyte membrane, so that the prepared silane-modified polyether polyol copolymer solid polymer electrolyte can have good electrochemical stability, with an electrochemical window greater than 4.5V and a room temperature ionic conductivity of 1×10 -5 S / cm-1×10 -3 S / cm.

[0044] In a specific embodiment of the present invention, the silane-modified polyether polyol copolymer may have the general formula (I):

[0045]

[0046] In the general formula (I), R1 can generally be a C1-C10 alkyl group, a C2-C10 alkene group or a C1-C5 alkoxy group; or a C1-C5 alkyl group, a C2-C5 alkene group or a C1-C3 alkoxy group; or a C1-C3 alkyl group, a C2-C3 alkene group or a C2-C3 alkoxy group.

[0047] In a specific embodiment, R1 can be selected from methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl, heptyl, octyl, nonyl, decyl, vinyl, propenyl, butenyl, pentenyl, methoxy, ethoxy, propoxy, butoxy, pentoxy, etc.

[0048] In the general formula (I), R2 may be a C1-C10 alkyl group; or a C1-C5 alkyl group; or a C1-C3 alkyl group.

[0049] In a specific embodiment, R2 can be selected from methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl, heptyl, octyl, nonyl, decyl, etc.

[0050] In the general formula (I), R3 is a polyether polyol unit, which may optionally include one or more other substituents.

[0051] In a specific embodiment, R3 can be or any two or three thereof. In R3, m, k and x are each independently selected from an integer of 1-1000, 1-800, 1-600, 1-400, 1-200, 1-100, 1-50, 50-1000, 50-800, 50-600, 50-400, 50-200, 50-100, 100-1000, 100-800, 100-600, 100-400, 100-200, 200-1000, 200-800, 200-600, 200-400, 400-1000, 400-800, 400-600, 600-1000, 600-800 or 800-1000.

[0052] In formula (I), n is an integer selected from 1-50, 1-40, 1-30, 1-20, 1-10, 1-5, 5-50, 5-40, 5-30, 5-20, 5-10, 10-50, 10-40, 10-30, 10-20, 20-50, 20-40, 20-30, 30-50, 30-40 or 40-50.

[0053] In the present invention, the amount of the silane-modified polyether polyol copolymer may be 10-65 wt%, 10-60 wt%, 10-55 wt%, 10-50 wt%, 10-45 wt%, 10-40 wt%, 10-35 wt%, 10-30 wt%, 10-25 wt%, 10-20 wt%, 10-15 wt%, 15-65 wt%, 15-60 wt%, 15-55 wt%, 15-50 wt%, 10-65 wt%, 10-60 wt%, 10-55 wt%, 10-50 wt%, 10-45 wt%, 10-40 wt%, 10-35 wt%, 10-30 wt%, 10-25 wt%, 10-20 wt%, 10-15 wt%, 15-65 wt%, 15-60 wt%, 10-55 wt%, 10-50 wt%, 10-65 wt%, 10-60 wt%, 10-55 wt%, 10-50 wt%, 10-45 wt%, 10-40 wt%, 10-35 wt%, 10-30 wt%, 10-25 wt%, 10-20 wt%, 10-15 wt%, 10- 5-45 wt%, 15-40 wt%, 15-35 wt%, 15-30 wt%, 15-25 wt%, 15-20 wt%, 20-65 wt%, 20-60 wt%, 20-55 wt%, 20-50 wt%, 20-45 wt%, 20-40 wt%, 20-35 wt%, 20-30 wt%, 20-25 wt%, 25-65 wt%, 25-60 wt%, 25-55 wt%, 25-50 wt%, 25-45 wt%. %, 25-40 wt%, 25-35 wt%, 25-30 wt%, 30-65 wt%, 30-60 wt%, 30-55 wt%, 30-50 wt%, 30-45 wt%, 30-40 wt%, 30-35 wt%, 35-65 wt%, 35-60 wt%, 35-55 wt%, 35-50 wt%, 35-45 wt%, 35-40 wt%, 40-65 wt%, 40-60 wt%, 40-55 wt%, 40-5 0 wt%, 40-45 wt%, 45-65 wt%, 45-60 wt%, 45-55 wt%, 45-50 wt%, 45-45 wt%, 45-40 wt%, 45-35 wt%, 45-30 wt%, 45-25 wt%, 45-20 wt%, 45-15 wt%, 50-65 wt%, 50-60 wt%, 50-55 wt%, 55-65 wt%, 55-60 wt%, 60-65 wt% or any value therebetween.

[0054] Lithium-containing electrolyte compounds

[0055] In the present invention, the lithium-containing electrolyte compound can be any lithium-containing compound used as a positive electrode material in a lithium-ion battery. The thermal decomposition temperature is greater than 160°C, and the compound is fully soluble in a mixed solvent of one or more of C1-C5 alcohols, C1-C5 nitriles, C1-C3 chloroalkanes, aliphatic N-alkyl substituted amides, or C2-C6 carbonate organic compounds. Typically, the lithium-containing compound includes, but is not limited to, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, manganese nickel cobalt composite oxide, lithium vanadium oxide, and lithium iron oxide.

[0056] In a specific embodiment, the lithium-containing compound includes but is not limited to: lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium difluorophosphate, lithium tetrafluoroborate, lithium bis(oxalatoborate) (LiBOB), lithium difluorooxalatoborate (LiDFOB), lithium trifluoromethanesulfonate (CF3SO3Li), lithium bis(trifluoromethanesulfonyl imide) (LiTFSI), lithium bis(fluorosulfonyl imide) (LiFSI), or any combination thereof.

[0057] In the present invention, the lithium-containing electrolyte compound is not particularly limited, as long as it is a lithium-containing compound positive electrode material commonly used in lithium-ion batteries in the art.

[0058] In the present invention, the amount of the lithium-containing electrolyte compound may be 5-90 wt%, 5-80 wt%, 5-70 wt%, 5-60 wt%, 5-50 wt%, 5-40 wt%, 5-30 wt%, 5-20 wt%, 20-90 wt%, 20-80 wt%, 20-70 wt%, 20-60 wt%, 20-50 wt%, 20-40 wt%, 20-30 wt%, 30-90 wt%, 30-80 wt%. %, 30-70 wt%, 30-60 wt%, 30-50 wt%, 30-40 wt%, 40-90 wt%, 40-80 wt%, 40-70 wt%, 40-60 wt%, 40-50 wt%, 50-90 wt%, 50-80 wt%, 50-70 wt%, 50-60 wt%, 60-90 wt%, 60-80 wt%, 60-70 wt%, 70-90 wt%, 70-80 wt%, 8-90 wt%, or any value therebetween.

[0059] crosslinking agent

[0060] In the present invention, the solid polymer electrolyte may not contain any cross-linking agent. In an embodiment of the present invention, in order to promote the formation of the solid polymer electrolyte, the solid polymer electrolyte may optionally contain a cross-linking agent.

[0061] In a specific embodiment, the cross-linking agent can be a silane coupling agent or a silicate compound, including but not limited to, one or more of N-n-butyl-3-aminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyldimethoxysilane, diethylaminomethyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, methyl orthosilicate, ethyl orthosilicate, and butyl orthosilicate.

[0062] In the present invention, the amount of the crosslinking agent can be 0-10 wt%, 0-6 wt%, 0-4 wt%, 0-2 wt%, 2-10 wt%, 2-6 wt%, 2-4 wt%, 4-10 wt%, 4-6 wt%, 6-10 wt%, or any value therebetween, based on the weight of the solid polymer electrolyte.

[0063] catalyst

[0064] In the present invention, the solid polymer electrolyte may not contain any catalyst. In an embodiment of the present invention, in order to promote the formation of the solid polymer electrolyte, the solid polymer electrolyte may optionally contain a catalyst. In some embodiments, the solid polymer electrolyte does not contain any organotin catalyst.

[0065] In a specific embodiment, the catalyst can be an organic bismuth catalyst, mainly including bismuth (tris (2-ethylhexanoate), bismuth trioctanoate, bismuth neodecanoate, bismuth isooctanoate, bismuth laurate, bismuth cyclohexaneate, bismuth carboxylate and any combination thereof.

[0066] In the present invention, the amount of the crosslinking agent can be 0-15 wt%, 0-10 wt%, 0-5 wt%, 0-1 wt%, 1-15 wt%, 1-10 wt%, 1-5 wt%, 5-15 wt%, 5-10 wt%, 10-15 wt%, or any value therebetween, based on the weight of the solid polymer electrolyte.

[0067] solid polymer electrolyte

[0068] In the present invention, the solid polymer electrolyte may comprise: a silane-modified polyethylene glycol polyether polyol copolymer, a lithium-containing electrolyte compound, an optional cross-linking agent, and an optional catalyst. In some embodiments, the solid polymer electrolyte may consist essentially of a silane-modified polyethylene glycol polyether polyol copolymer, a lithium-containing electrolyte compound, an optional cross-linking agent, and an optional catalyst. In some embodiments, the solid polymer electrolyte may consist essentially of a silane-modified polyethylene glycol polyether polyol copolymer, a lithium-containing electrolyte compound, an optional cross-linking agent, and an optional catalyst.

[0069] Specifically, the silane-modified polyether polyol copolymer solid polymer electrolyte of the present invention can be prepared mainly by reacting a mixture of a silane-modified polyether polyol copolymer, a lithium-containing electrolyte compound, a cross-linking agent, and a catalyst. Based on the weight of the mixture, the silane-modified polyether polyol copolymer accounts for 10-65 weight % or 15-55 weight % of the mixture; the cross-linking agent accounts for 0-10 weight % or 0.5-5 weight % of the mixture; the catalyst accounts for 0-15 weight % or 0.1 weight % to 6.0 weight % of the mixture; and the lithium-containing electrolyte compound accounts for 5-90 weight % or 15.0 weight % to 75.0 weight % of the mixture.

[0070] Preparation of solid polymer electrolytes

[0071] In the present invention, a solid polymer electrolyte is prepared by the following steps:

[0072] (1) dissolving a lithium-containing electrolyte compound in an organic solvent to form a lithium salt solution;

[0073] (2) adding the silane-modified polyether polyol copolymer to the lithium salt solution and stirring under a sealed condition or in an inert atmosphere;

[0074] (3) optionally adding a cross-linking agent and / or a catalyst and continuing to stir under sealed conditions; and

[0075] (4) Film formation and drying are performed to obtain a solid polymer electrolyte containing the silane-modified polyether polyol copolymer.

[0076] In some embodiments, the silane-modified polyether polyol copolymer is added to the lithium salt solution and stirred under sealed conditions for 1-24 hours, 1-16 hours, 1-8 hours, 8-24 hours, 8-16 hours, 16-24 hours, or any value therebetween.

[0077] In some embodiments, the film forming is carried out at a relative humidity of 5.0-95.0%, 5.0-80.0%, 5.0-60.0%, 5.0-40.0%, 5.0-20.0%, 20.0-95.0%, 20.0-80.0%, 20.0-60.0%, 20.0-40.0%, 40.0-95.0%, 40.0-80.0%, 40.0-60.0%, 60.0-95.0%, 60.0-80.0%, 80.0-95.0%, or any value therebetween.

[0078] In some embodiments, the drying is performed at a temperature of 10-80°C, 10-60°C, 10-40°C, 10-20°C, 20-80°C, 20-60°C, 20-40°C, 40-80°C, 40-60°C, 60-80°C, or any value therebetween.

[0079] organic solvents

[0080] In the present invention, the organic solvent used to dissolve the lithium-containing electrolyte compound and provide for the reaction is not particularly limited. In some embodiments, the organic solvent is selected from a combination of one or more of C1-C5 alcohols, C1-C5 nitriles, C1-C3 chloroalkanes, aliphatic N-alkyl substituted amides, and C2-C6 carbonates; preferably, the organic solvent is selected from one or more of methanol, ethanol, ethylene glycol, acetonitrile, chloroform, N-methylpyrrolidone, N,N-dimethylformamide and N,N-dimethylacetamide, dimethyl sulfoxide, dimethyl carbonate, ethylene carbonate, and propylene carbonate.

[0081] In a specific embodiment, the preparation method of the silane-modified polyether polyol copolymer solid polymer electrolyte comprises the following steps:

[0082] A lithium-containing electrolyte compound is dissolved in an organic solvent to prepare a conductive lithium salt solution; a corresponding weight percentage of a silane-modified polyether polyol copolymer is weighed and added to the conductive lithium salt solution, and the solution is fully stirred under a sealed state for 1-24 hours, preferably 2-12 hours; a corresponding weight percentage of a cross-linking agent and a catalyst are then added, and the solution is further sealed and stirred; a film is formed under a humidity of 5.0-95.0%, preferably 10.0-85.0%, and the film is fully dried at a temperature of 10-80°C, preferably 20-65°C, to obtain a silane-modified polyether polyol copolymer solid polymer electrolyte.

[0083] In a specific embodiment, the weight average molecular weight of the silane-modified polyether polyol copolymer is 1000-45000, preferably 2000-36000, and its structure is shown in formula (1):

[0084]

[0085] Wherein, R1 is a C1-C5 alkane group, a C1-C5 olefin group or a C1-C5 alkoxy group, R2 is a C1-C10 alkane group, and R3 is or or Or a copolymer or blend of any two or three kinds of the above, wherein n is an integer from 1 to 50, preferably an integer from 1 to 15, and m, k, and x are each an integer from 1 to 1000, preferably an integer from 3 to 500.

[0086] In the present invention, the organic solvent is one or a mixture of C1-C5 alcohols, C1-C5 nitriles, C1-C3 chloroalkanes, aliphatic N-alkyl substituted amides, or C2-C6 carbonate organic compounds. For example, one or more of methanol, ethanol, ethylene glycol, acetonitrile, chloroform, N-methylpyrrolidone, N,N-dimethylformamide and N,N-dimethylacetamide, dimethyl sulfoxide, dimethyl carbonate, ethylene carbonate, and propylene carbonate.

[0087] In the present invention, the volume of the lithium salt anion is greater than The thermal decomposition temperature is higher than 160°C, and the material can be fully dissolved in a mixed solvent of one or more of C1-C5 alcohols, C1-C5 nitriles, or C1-C3 chloroalkanes, or aliphatic N-alkyl substituted amides, or C2-C6 carbonate organic substances, for example, one or more of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium difluorophosphate, lithium tetrafluoroborate, lithium bis(oxalatoborate) (LiBOB), lithium difluorooxalatoborate (LiDFOB), lithium trifluoromethanesulfonate (CF3SO3Li), lithium bis(trifluoromethylsulfonyl imide) (LiTFSI), and lithium bis(fluorosulfonyl imide) (LiFSI).

[0088] In the present invention, the cross-linking agent is a silane coupling agent or a silicate compound, for example, one or more of N-n-butyl-3-aminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyldimethoxysilane, diethylaminomethyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, methyl orthosilicate, ethyl orthosilicate, and butyl orthosilicate.

[0089] In the present invention, the catalyst is an organic bismuth catalyst, mainly including one or more of bismuth (tris(2-ethylhexanoate), bismuth trioctanoate, bismuth neodecanoate, bismuth isooctanoate, bismuth laurate, bismuth cyclohexaneate, and bismuth carboxylate.

[0090] The present invention will be further described in detail below with reference to specific examples to make the advantages of the present invention more apparent. It should be understood that the contents herein are for illustration only and are not intended to limit the scope of the present invention. The experimental methods in the following examples, where specific conditions are not specified, were generally carried out under conventional conditions or under conditions recommended by the manufacturer.

[0091] Example 1

[0092] Weigh 15.0g of lithium hexafluorophosphate (LiPF6) and 27.86g of a silane-modified polyethylene glycol copolymer with a weight-average molecular weight of 2000, add them in sequence to a mixed solvent consisting of 35mL of acetonitrile and 5mL of propylene carbonate, stir them thoroughly for 2 hours under sealing, then add 0.22g of 3-aminopropylmethyldiethoxysilane crosslinker and 2.6g of bismuth isooctanoate catalyst, continue to seal and stir, form a film at a humidity of 10.0%, and then fully dry it at 20°C to obtain a silane-modified polyethylene glycol copolymer solid polymer electrolyte.

[0093] Example 2

[0094] Weigh 15.0g of lithium hexafluorophosphate (LiPF6) and 5.0g of a silane-modified polyethylene glycol copolymer with a weight-average molecular weight of 36,000, and add them in turn to 35mL of propylene carbonate solvent, stir them thoroughly under sealing for 12 hours, then add 0.022g of 3-aminopropylmethyldiethoxysilane crosslinker and 0.043g of bismuth isooctanoate catalyst, continue to seal and stir, and form a film at a humidity of 85.0%. After film formation, fully dry it at a temperature of 65°C to obtain a silane-modified polyethylene glycol copolymer solid polymer electrolyte.

[0095] Example 3

[0096] 15.0 g of lithium hexafluorophosphate (LiPF6) and 25.0 g of a silane-modified polypropylene glycol copolymer containing an aminoacetate group (-NHCOO-) with a weight-average molecular weight of 12,000 were weighed and added sequentially to 15 mL of ethylene carbonate solvent, stirred thoroughly for 10 hours under a sealed state, and formed into a film at a humidity of 95.0%. After film formation, the film was fully dried at a temperature of 85°C to obtain a silane-modified polypropylene glycol copolymer solid polymer electrolyte.

[0097] Example 4

[0098] 15.0 g of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and 25.0 g of a silane-modified poly(propylene oxide) copolymer with a weight-average molecular weight of 12,000 were weighed and added sequentially to 15 mL of ethylene carbonate solvent, stirred thoroughly for 10 hours under a sealed state, and formed into a film at a humidity of 95.0%. After film formation, the film was fully dried at a temperature of 85°C to obtain a silane-modified poly(propylene glycol) copolymer solid polymer electrolyte.

[0099] Example 5

[0100] Weigh 25.0 g of lithium bistrifluoromethylsulfonyl imide (LiTFSI) and 25.0 g of silane-modified polyethylene glycol-polyphenylene ether copolymer with a weight average molecular weight of 12000, add them into 15 mL of N-methylpyrrolidone solvent in sequence, stir them thoroughly under sealing for 8 hours, then add 1.0 g of ethyl orthosilicate crosslinker and 1.5 g of bismuth laurate catalyst, continue to seal and stir, form a film under humidity of 65.0%, and then fully dry it at 55°C to obtain a silane-modified polyethylene glycol-polyphenylene ether copolymer solid polymer electrolyte.

[0101] Example 6

[0102] 25.0 g of lithium bis(oxalatoborate) (LiBOB) and 15.0 g of a silane-modified polyethylene glycol-poly(propylene oxide) copolymer with a weight average molecular weight of 8000 were weighed and added sequentially to a mixed solvent consisting of 10 mL of ethanol and 5 mL of ethylene carbonate. The mixture was stirred for 7.5 hours under sealing conditions, and then 1.0 g of γ-glycidyloxypropyltrimethoxysilane crosslinker and 1.2 g of bismuth neodecanoate catalyst were added. The mixture was further sealed and stirred, and a film was formed at a humidity of 55.0%. After film formation, the film was fully dried at 50° C. to obtain a silane-modified polyethylene glycol-poly(propylene oxide) copolymer solid polymer electrolyte.

[0103] Test Case

[0104] The properties of the silane-modified polyether polyol copolymer solid polymer electrolytes prepared in Examples 1-6 were tested. The specific testing method is as follows:

[0105] Film thickness

[0106] The thickness of the solid polymer electrolyte membrane was measured using a micrometer (accuracy 0.01 mm). Five random points were measured and the average value was calculated.

[0107] Ionic conductivity

[0108] The electrochemical impedance spectroscopy (EIS) method was used to test the ionic conductivity of the solid polymer electrolyte. Specifically, the solid polymer electrolyte membrane was sandwiched between two symmetrical stainless steel (SS) electrodes, and a 2.32 inch button cell was assembled. The impedance of the cell was measured according to the formula Calculate the ionic conductivity of the solid polyelectrolyte, where L is the thickness of the sample (cm) and S is the area of ​​the sample (cm 2 ), R is the impedance of the sample (Ω).

[0109] The test results of Examples 1-6 are shown in Table 1.

[0110]

[0111]

[0112] As can be seen from Table 1 above, the solid polymer electrolyte membranes described in Examples 1-6 have high room temperature ionic conductivities, which are higher than the ionic conductivities of conventional solid polymer electrolytes in the prior art (for example, the ionic conductivity of conventional solid polymer electrolytes is usually only σ≈10 -5 S / cm, the “2×10 -5 -1×10 -4 S / cm”). In Example 3, the room temperature ionic conductivity of the solid polymer electrolyte membrane is even as high as 1.02×10 -3 S / cm.

[0113] Moreover, Examples 1-6 of the present invention use organic bismuth catalysts to replace the organic tin catalysts used in existing electrolyte technologies. Therefore, the solid polymer electrolytes described in Examples 1-6 have the advantages of being environmentally friendly, low cost, having good hydrolysis stability, low toxicity, and low radioactivity.

Claims

1. A solid polymer electrolyte, comprising: (1) one or more silane-modified polyether polyol copolymers; (2) one or more lithium-containing electrolyte compounds; (3) optionally a cross-linking agent; and (4) optional catalyst; in, The silane-modified polyether polyol copolymer has the general formula (I): In the formula, R1 is a C1-C5 alkane group, a C1-C5 olefin group or a C1-C5 alkoxy group; R2 is a C1-C10 alkane group; R3 is or a combination of any two or three of them; wherein n is an integer selected from 1-50, and m, k and x are each an integer selected from 1-1000.

2. The solid polymer electrolyte according to claim 1, wherein Based on the weight of the solid polymer electrolyte, The silane-modified polyether polyol copolymer is 10-65% by weight; The lithium-containing electrolyte compound is 5-90% by weight; The cross-linking agent is 0-10% by weight; and The catalyst is 0-15% by weight.

3. The solid polymer electrolyte according to claim 1, wherein The weight average molecular weight of the silane-modified polyether polyol copolymer is 1,000-45,000.

4. The solid polymer electrolyte according to claim 1, wherein The lithium-containing electrolyte compound includes lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium difluorophosphate, lithium tetrafluoroborate, lithium bis(oxalatoborate) (LiBOB), lithium difluorooxalatoborate (LiDFOB), lithium trifluoromethanesulfonate (CF3SO3Li), lithium bis(trifluoromethanesulfonyl imide) (LiTFSI), lithium bis(fluorosulfonyl imide) (LiFSI), or any combination thereof.

5. The solid polymer electrolyte according to claim 1, wherein The cross-linking agent is selected from silane coupling agents, silicate compounds and combinations thereof.

6. The solid polymer electrolyte according to claim 1, wherein The crosslinking agent is selected from N-n-butyl-3-aminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyldimethoxysilane, diethylaminomethyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, methyl orthosilicate, ethyl orthosilicate, butyl orthosilicate and combinations thereof.

7. The solid polymer electrolyte according to claim 1, wherein The catalyst is an organic bismuth catalyst.

8. The solid polymer electrolyte according to claim 1, wherein The catalyst is selected from bismuth (tris(2-ethylhexanoate), bismuth trioctanoate, bismuth neodecanoate, bismuth isooctanoate, bismuth laurate, bismuth naphthenate, bismuth carboxylate, and combinations thereof.

9. A method for preparing the solid polymer electrolyte according to claim 1, comprising: (1) dissolving a lithium-containing electrolyte compound in an organic solvent to form a lithium salt solution; (2) adding the silane-modified polyether polyol copolymer to the lithium salt solution and stirring under a sealed condition; (3) optionally adding a cross-linking agent and / or a catalyst and continuing to stir under sealed conditions; and (4) Film formation and drying are performed to obtain a solid polymer electrolyte containing the silane-modified polyether polyol copolymer.

10. The method of claim 9, wherein: The organic solvent is selected from one or more combinations of C1-C5 alcohols, C1-C5 nitriles, C1-C3 chloroalkanes, aliphatic N-alkyl substituted amides, and C2-C6 carbonates.

11. The method of claim 9, wherein: The organic solvent is selected from one or more of methanol, ethanol, ethylene glycol, acetonitrile, chloroform, N-methylpyrrolidone, N,N-dimethylformamide and N,N-dimethylacetamide, dimethyl sulfoxide, dimethyl carbonate, ethylene carbonate, and propylene carbonate.

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