High-adhesion flame-retardant solid polymer electrolyte prepared by in-situ solidification and application

Abstract

The invention relates to a solid polymer electrolyte, in particular to a high-adhesion flame-retardant solid polymer electrolyte prepared through in-situ solidification and application. The solid polymer electrolyte is prepared from an electrolyte component in a porous support material through in-situ solidification; wherein the electrolyte comprises the following components: an intrinsic non-combustible phosphate organic solvent, lithium salt, a cyanoacrylate monomer and an initiator; the thickness of the solid polymer electrolyte is 3-1000 [mu] m, the room temperature ionic conductivity is 3 * 10 <-5 >-8 * 10 <-3 > S / cm, and the electrochemical window is greater than or equal to 4.6 V. The high-adhesion flame-retardant solid polymer electrolyte disclosed by the invention has extremely excellent interfacial compatibility with a positive electrode and a negative electrode and high adhesion characteristic, and can be well compatible and self-adaptive to volume change and the like of a solid-state lithium battery during long-period circulation; the method is suitable for constructing a long-life solid polymer lithium metal battery without additional stacking pressure and a solid polymer lithium ion battery with a silicon monoxide negative electrode.

Description

Technical Field

[0001] The present invention relates to a solid polymer electrolyte, in particular to a highly adhesive flame-retardant solid polymer electrolyte prepared in situ by solidification and its application in a long-life solid polymer lithium battery without the need for additional stacking pressure. Background Art

[0002] In recent years, with the rapid development of electric vehicles and renewable energy storage systems, the demand for high-energy-density and high-safety secondary batteries has surged. Solid-state lithium batteries have become a core research direction jointly focused on by academia and industry due to their energy density potential and high safety. However, traditional liquid electrolytes are based on volatile and flammable organic solvents (such as ethylene carbonate, ethyl methyl carbonate, etc.). Their high flammability makes it very easy for batteries to cause thermal runaway under conditions of high temperature or abuse such as puncture and overcharging, leading to combustion or explosion accidents. In addition, lithium dendrites formed by lithium metal anodes during repeated charge and discharge can penetrate the liquid electrolyte and diaphragm, causing internal short circuits, further exacerbating safety hazards. At the same time, the interfacial side reactions between liquid electrolytes and high-energy electrode materials (such as high-nickel ternary cathodes or lithium metal anodes) (such as uneven growth of SEI films and electrolyte decomposition) will continue to consume active lithium ions, resulting in a decrease in Coulomb efficiency and a shortened cycle life.

[0003] In this context, solid electrolytes can completely or partially replace liquid solvents, which can not only eliminate the risk of electrolyte leakage and combustion, but also inhibit the growth of lithium dendrites through a matrix with a certain mechanical strength. Solid polymer electrolytes still face multiple technical bottlenecks: limited ion conductivity. For example, traditional polymer matrices such as polyethylene oxide have low room temperature conductivity of less than 10 due to segment rigidity or low ion transport efficiency at low temperatures. -4 S / cm, which is difficult to meet the needs of practical applications; insufficient mechanical strength leads to lithium dendrite penetration, and poor interface contact triggers side reactions, significantly reducing the cycle life; the polymer matrix itself is flammable and easily decomposes or burns at high temperatures.

[0004] In addition, the practical application of solid-state batteries is hindered by certain technical issues, including the high stacking pressure required for these batteries. For example, in order to solve the problem of voids formed inside the solid electrode due to volume change and the subsequent blockage of lithium ion transmission, existing solid-state lithium batteries usually need to apply a high stacking pressure (usually tens of megapascals). The redundant pressurizing device will significantly reduce the energy density of the battery and increase the cost, which is not conducive to the practical development of solid-state lithium batteries.

[0005] In this context, in order to truly promote the large-scale application of solid-state lithium batteries, it is urgently necessary to develop highly adhesive flame-retardant solid polymer electrolytes. While ensuring the high safety and long life of solid-state lithium batteries, relying on highly adhesive flame-retardant solid polymer electrolytes can achieve the interfacial stability and high adhesiveness of solid polymer lithium batteries, thus eliminating the need for redundant pressing devices, and then constructing truly high-energy-density, high-safety and long-life solid polymer lithium batteries. Summary of the Invention

[0006] The purpose of the present invention is to provide a highly adhesive flame-retardant solid polymer electrolyte prepared by in-situ solidification and its application in a long-life solid polymer lithium battery that does not require additional stacking pressure.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A highly adhesive flame-retardant solid polymer electrolyte prepared by in-situ solidification, where the solid polymer electrolyte is obtained by in-situ solidification of electrolyte components in a porous support material; among them, the electrolyte components are intrinsically non-flammable phosphate organic solvents, lithium salts, cyanoacrylate monomers and initiators; the thickness of the solid polymer electrolyte is 3 μm - 1000 μm, the room temperature ionic conductivity is 3×10 -5 S / cm - 8×10 -3 S / cm, and the electrochemical window ≥ 4.6V.

[0009] The obtained electrolyte has characteristics such as high oxidation stability, high compatibility with the negative electrode, and intrinsic non-flammability.

[0010] The electrolyte components are calculated by weight percentage, 5% - 25% lithium salt, 15 - 47% cyanoacrylate monomers, 0.01% - 5% initiator, and the balance is intrinsically non-flammable phosphate organic solvent; among them, the lithium salt concentration is 0.5 mol / L - 1.5 mol / L in terms of the molar concentration of lithium ions.

[0011] The intrinsically non-flammable phosphate organic solvent is trimethyl phosphate shown in Formula 1;

[0012]

[0013] The lithium salt is lithium difluorooxalate borate, lithium bis(oxalato)borate, lithium difluoro(1,2-dihydroxyethane-1,1,2,2-tetracyanato)borate or lithium perfluorooctyl aluminate; preferably lithium difluorooxalate borate, lithium bis(oxalato)borate.

[0014] The cyanoacrylate monomer is one or more of methyl 2-cyanoacrylate, ethyl 2-cyanoacrylate, n-butyl cyanoacrylate, alkoxy cyanoacrylate, octyl cyanoacrylate, and 2-octyl cyanoacrylate; preferably methyl 2-cyanoacrylate and ethyl 2-cyanoacrylate.

[0015] The initiator is one or more of caprolactam, valerolactam, butyl lithium, azobisisobutyronitrile, azobisisoheptonitrile, hydrogen peroxide, and ammonium persulfate; preferably azobisisobutyronitrile and azobisisoheptonitrile.

[0016] The porous support material is one or more of a polyethylene separator, a polypropylene separator, a polyethylene / polypropylene / polyethylene three-layer composite separator, a nylon non-woven membrane, a seaweed fiber non-woven membrane, a cellulose non-woven membrane, bacterial cellulose, a glass fiber, a polyethylene terephthalate film, a polyimide non-woven membrane, a polyamide membrane, a spandex membrane, an aramid membrane, a polytetrafluoroethylene separator, and an inorganic porous membrane. Preferably, it is a cellulose non-woven membrane, bacterial cellulose, a polyimide non-woven membrane, or an aramid membrane.

[0017] A method for preparing the high-adhesion flame-retardant solid polymer electrolyte described above,

[0018] a) In a glove box filled with argon, use a molecular sieve to remove water from the intrinsically non-flammable phosphate organic solvent.

[0019] b) Mix the solvent and lithium salt treated in step a) evenly according to the above ratio, and then add the cyanoacrylate monomer and the initiator, and stir evenly.

[0020] c) Drop the above uniformly mixed mixture onto the porous support material to make it completely infiltrated.

[0021] d) Leave the porous support material infiltrated with the mixture at 20°C - 30°C for 0.1 hrs - 30 hrs to solidify the mixture in-situ, thereby obtaining the high-adhesion flame-retardant solid polymer electrolyte.

[0022] An application of the high-adhesion flame-retardant solid polymer electrolyte described above, and the application of the solid polymer electrolyte in a long-life solid polymer lithium battery (solid polymer lithium metal battery and long-life solid polymer lithium-ion battery with a silicon suboxide negative electrode) without additional stacking pressure.

[0023] A long-life solid polymer lithium battery without additional stacking pressure, including a positive electrode, a negative electrode, and a solid polymer electrolyte between the positive and negative electrodes, and the solid polymer electrolyte is the high-adhesion flame-retardant solid polymer electrolyte described above.

[0024] The positive electrode is one of a lithium iron phosphate positive electrode, a lithium manganese iron phosphate positive electrode, a lithium cobalt oxide positive electrode, a ternary material (such as lithium nickel cobalt manganese oxide NCM, lithium nickel cobalt aluminate NCA), a lithium manganese oxide, a lithium nickel manganese oxide, and a lithium-rich manganese-based positive electrode; the negative electrode is one of a lithium metal negative electrode, a lithium alloy negative electrode, a lithium tin alloy negative electrode, a lithium silicon alloy negative electrode, a metal tin negative electrode, a silicon negative electrode, a tin-based oxide negative electrode, a silicon monoxide negative electrode, a lithium titanate negative electrode, hard carbon, soft carbon, carbon nanotubes, graphene, and iron oxide.

[0025] The lithium battery is assembled into a button-type battery, a steel-shell cylindrical battery, an aluminum-shell cylindrical battery, a steel-shell square battery, an aluminum-shell square battery, or an aluminum-plastic film soft-pack battery.

[0026] The advantages and positive effects of the present invention are:

[0027] The present invention provides a highly adhesive flame-retardant solid polymer electrolyte and a long-life solid polymer lithium battery constituted thereby without additional stacking pressure. Among them, due to its unique molecular structure and strong adhesion characteristics, cyanoacrylate has extremely strong adhesion and permeability when polymerized and matched with phosphate esters, and can enter the solid electrode to form voids and maintain good adhesion at the positive and negative electrode interfaces, synergistically solving problems such as lithium-ion transport blockage. Furthermore, it realizes the long-cycle stable operation of the solid polymer lithium battery without additional stacking external force, and at the same time solves the dilemma that conventional solid lithium batteries need additional pressure to achieve stable cycling, which is beneficial to promoting the large-scale manufacturing of solid lithium batteries; in addition, the highly adhesive flame-retardant solid polymer electrolyte is prepared by in-situ solidification, with a simple molding process, high room-temperature ionic conductivity, high oxidation stability, high compatibility with the negative electrode, and intrinsic non-flammability; it has good mechanical properties and can effectively inhibit the growth of lithium dendrites. At the same time, the highly adhesive flame-retardant solid polymer electrolyte has extremely excellent interfacial compatibility and high adhesion characteristics with the positive and negative electrodes, and can well accommodate and adapt to volume changes during long-cycle cycling of solid lithium batteries, etc. Therefore, no additional device is required to provide stacking pressure. Since the constructed solid lithium battery does not require additional pressurizing accessories, it can greatly improve the energy density of the solid lithium battery while enhancing safety, which greatly promotes the development of solid lithium batteries and is a very promising solid polymer electrolyte system.

[0028] Therefore, the highly adhesive flame-retardant solid polymer electrolyte is suitable for constructing a long-life solid polymer lithium battery (solid polymer lithium metal battery and long-life solid polymer lithium-ion battery with a silicon monoxide negative electrode) without additional stacking pressure. Description of the Drawings

[0029] Figure 1 It is a digital photo of the highly adhesive flame-retardant solid polymer electrolyte before and after polymerization provided in Example 1 of the present invention.

[0030] Figure 2 It is the ignition experiment of the strip glass fiber of the high-adhesion flame-retardant solid polymer electrolyte provided in Embodiment 1 of the present invention.

[0031] Figure 3 It is the curve obtained by linear sweep voltammetry test of the lithium-on-steel battery assembled with the high-adhesion flame-retardant solid polymer electrolyte provided in Embodiment 1 of the present invention.

[0032] Figure 4 It is the long-cycle performance curve of the NCM811 / Li lithium metal battery assembled with the high-adhesion flame-retardant solid polymer electrolyte provided in Embodiment 1 of the present invention within the voltage range of 2.5V to 4.25V under the condition of 0.2C.

[0033] Figure 5 It is the long-cycle performance curve of the NCM811 / silicon monoxide lithium-ion battery assembled with the high-adhesion flame-retardant solid polymer electrolyte provided in Embodiment 2 of the present invention within the voltage range of 2.5V to 4.2V under the condition of 0.2C.

[0034] Figure 6 It is the long-cycle performance curve of the NCM622 / Li lithium metal battery assembled with the high-adhesion flame-retardant solid polymer electrolyte provided in Embodiment 4 of the present invention within the voltage range of 2.5V to 4.25V under the condition of 0.2C.

[0035] Figure 7 It is the long-cycle performance curve of the NCM811 / Li lithium metal battery assembled with the electrolyte provided in Comparative Example 1 of the present invention within the voltage range of 2.5V to 4.25V under the condition of 0.2C.

[0036] Figure 8 It is the digital photo of the ignition experiment of the electrolyte provided in Comparative Example 2 of the present invention.

[0037] Figure 9 It is the curve obtained by linear sweep voltammetry test of the lithium-on-steel battery assembled with the electrolyte provided in Comparative Example 2 of the present invention.

[0038] Figure 10 It is the long-cycle performance curve of the NCM811 / silicon monoxide lithium-ion battery assembled with the electrolyte provided in Comparative Example 2 of the present invention within the voltage range of 2.5V to 4.2V under the condition of 0.2C. Detailed Embodiments

[0039] The following further illustrates the detailed embodiments of the present invention in combination with examples. It should be noted that the detailed embodiments described herein are only for explaining and interpreting the present invention and are not limited to the present invention.

[0040] The thickness of the highly adhesive flame-retardant solid polymer electrolyte is 3 μm-1000 μm, and the room temperature ionic conductivity is 3×10 -5 S / cm-8×10 -3 S / cm, electrochemical window ≥4.6V. At the same time, the high-adhesion flame-retardant solid polymer electrolyte has extremely excellent interface compatibility and high adhesion characteristics with the positive and negative electrodes, and can be well compatible and adaptive to the volume changes of solid-state lithium batteries during long-cycle cycles, etc., so no additional device is required to provide stacking pressure. Therefore, the high-adhesion flame-retardant solid polymer electrolyte of the present invention is particularly suitable for constructing long-life solid-state polymer lithium metal batteries that do not require additional stacking pressure, and solid-state polymer lithium-ion batteries with silicon oxide negative electrodes. Since the constructed solid-state lithium battery does not require additional pressurized accessories, the energy density of the solid-state lithium battery can be greatly improved while improving safety, greatly promoting the development of solid-state lithium batteries, and is a very potential solid polymer electrolyte system.

[0041] Example 1

[0042] The entire electrolyte preparation process was carried out in an argon atmosphere glove box (H2O<0.5ppm, O2<0.5ppm). The organic trimethyl phosphate solvent was dehydrated using 4A molecular sieves and set aside. Then, the following steps were followed: Under magnetic stirring conditions, 1.2g of trimethyl phosphate solvent treated in the above dehydration method was weighed and added to a glass bottle, and then 0.10g of lithium difluorooxalate borate was added under stirring conditions. After the lithium salt was completely dissolved to obtain a phosphate base liquid, 0.98g of methyl 2-cyanoacrylate was added and continued to stir for 30 minutes until uniformly mixed, and then 0.10g of azobisisobutyronitrile initiator was added, mixed evenly as an electrolyte component, and set aside (see Figure 1 ); using eight-series ternary nickel-cobalt-manganese (NCM811) as the positive electrode, lithium metal as the negative electrode, and polypropylene as the porous support material (the mixed electrolyte components are dripped on the polypropylene to make it completely soaked), and then kept at 30°C for 20 hours to allow the electrolyte material to solidify in situ on the porous support material, to obtain a solid-state NCM811 / Li lithium battery with a 20μm thick, highly adhesive, flame-retardant solid polymer electrolyte.

[0043] Depend on Figure 1 It can be seen that the highly adhesive flame-retardant solid polymer electrolyte prepared by in-situ solidification is transparent and does not flow.

[0044] Lithium battery cycle performance test: The battery charge and discharge range is 2.5V ~ 4.25V, the charge and discharge rate is 0.2C, and the test temperature is 25℃ (see Table 1 and Figure 4 ).

[0045] Combustion test: Cut the glass fiber into thin strips, soak it with 0.5g electrolyte component, ignite it with an open flame, and record the self-extinguishing time as 0s / g after removing the fire source (see Figure 2 ).

[0046] Electrochemical window test: Li-steel cells were assembled using the prepared electrolyte. Linear sweep voltammetry was used to scan from the open circuit voltage of the cell to 6 V at 1 mV / s, and the electrochemical window was recorded as 4.70 V (see Figure 3 ).

[0047] Ion conductivity test: Using the prepared electrolyte, a steel-to-steel cell was assembled, and the impedance was measured and the room temperature ionic conductivity of the electrolyte was calculated. The recorded ionic conductivity was 1.53 mS / cm (see Table 1).

[0048] Example 2

[0049] The entire electrolyte preparation process was carried out in an argon atmosphere glove box (H2O<0.5ppm, O2<0.5ppm). The organic trimethyl phosphate solvent was dehydrated using 4A molecular sieves and set aside. Then, the following steps were followed: Under magnetic stirring, 1.2g of trimethyl phosphate solvent treated by the above dehydration method was weighed and added to a glass bottle, and then 0.2g of lithium difluorooxalate borate was added under stirring. After the lithium salt was completely dissolved to obtain a phosphate base liquid, 0.62g of The ethyl 2-cyanoacrylate was stirred for 30 minutes until it was evenly mixed, and then 0.05 g of caprolactam initiator was added and mixed evenly as an electrolyte component for standby use; the octa-series ternary nickel-cobalt-manganese (NCM811) was used as the positive electrode, silicon dioxide was used as the negative electrode, and glass fiber was used as the porous support material (the mixed electrolyte components were dripped on the glass fiber to make it completely soaked), and then kept at 30°C for 18 hours to allow the electrolyte material to solidify in situ in the porous support material, thereby obtaining a solid-state NCM811 / silicon dioxide lithium-ion battery with a 100 μm thick solid polymer electrolyte with high adhesion.

[0050] Lithium battery cycle performance test: The battery charge and discharge range is 2.5V~4.25V, the charge and discharge rate is 0.2C, and the test temperature is 25℃. (See Table 1 and Figure 5 )

[0051] Combustion test: Cut the glass fiber into thin strips, soak it with 0.5g electrolyte component, ignite it with an open flame, and record the self-extinguishing time as 0s / g after removing the fire source. (See Table 1)

[0052] Electrochemical window test: Using the prepared electrolyte, a lithium-steel battery was assembled. Linear sweep voltammetry was used to scan from the open circuit voltage of the battery to 6V at 1mV / s, and the electrochemical window was recorded as 4.81V. (See Table 1)

[0053] Ion conductivity test: Use the prepared electrolyte to assemble a steel-to-steel battery. Measure the impedance and calculate the room temperature ionic conductivity of the electrolyte. The recorded ionic conductivity is 1.78 mS / cm. (See Table 1)

[0054] Example 3

[0055] The entire electrolyte preparation process was carried out in an argon atmosphere glove box (H2O<0.5ppm, O2<0.5ppm). The organic trimethyl phosphate solvent was dehydrated using 4A molecular sieves and set aside. Then, the following steps were followed: Under magnetic stirring, 1.2g of trimethyl phosphate solvent treated by the above dehydration method was weighed and added to a glass bottle, and then 0.075g of lithium difluorooxalate borate was added under stirring. After the lithium salt was completely dissolved, a phosphate base liquid was obtained, and 0.9g of n-butyl cyanoacrylate was added to continue The mixture was stirred for 30 minutes until evenly mixed, and then 0.06 g of azobisisobutyronitrile initiator was added and mixed evenly as an electrolyte component for standby use. Lithium iron phosphate was used as the positive electrode, lithium metal as the negative electrode, and cellulose as the porous support material (the evenly mixed electrolyte components were dripped onto the cellulose to completely soak it), and then kept at 30°C for 10 hours to allow the electrolyte material to solidify in situ in the porous support material, thereby obtaining a solid lithium iron phosphate / Li lithium metal battery with a 15 μm thick, highly adhesive, flame-retardant solid polymer electrolyte.

[0056] Lithium battery cycle performance test: The battery charge and discharge range is 2.5V~3.8V, the charge and discharge rate is 1C, and the test temperature is 25℃. (See Table 1)

[0057] Combustion test: Cut the glass fiber into thin strips, soak it with 0.5g electrolyte component, ignite it with an open flame, and record the self-extinguishing time as 0s / g after removing the fire source. (See Table 1)

[0058] Electrochemical window test: Using the prepared electrolyte, a lithium-steel battery was assembled. Linear sweep voltammetry was used to scan from the open circuit voltage of the battery to 6V at 1mV / s, and the electrochemical window was recorded as 4.92V. (See Table 1)

[0059] Ion conductivity test: Use the prepared electrolyte to assemble a steel-to-steel battery. Measure the impedance and calculate the room temperature ionic conductivity of the electrolyte. The recorded ionic conductivity is 1.85 mS / cm. (See Table 1)

[0060] Example 4

[0061] The entire electrolyte preparation process was carried out in an argon atmosphere glove box (H2O<0.5ppm, O2<0.5ppm). The organic trimethyl phosphate solvent was dehydrated using 4A molecular sieves and set aside. Then, the following steps were followed: Under magnetic stirring conditions, 1.2g of trimethyl phosphate solvent treated by the above dehydration method was weighed and added to a glass bottle, and then 0.11g of lithium dioxalate borate was added under stirring conditions. After the lithium salt was completely dissolved to obtain a phosphate base liquid, 0.81g of cyanoacrylate alkoxy ester was added and continued to stir for 30 minutes until uniformly mixed. Then add 0.08g of hydrogen peroxide initiator, mix evenly and use it as an electrolyte component for standby use; use six-series ternary nickel cobalt manganese (NCM622) as the positive electrode, lithium metal as the negative electrode, and polyethylene terephthalate as the porous support material (the mixed electrolyte components are dripped on the polyethylene terephthalate to make it completely infiltrated), and then keep it at 30°C for 20 hours to allow the electrolyte material to solidify in situ in the porous support material, and obtain a 50μm thick solid-state NCM622 / Li lithium battery with a highly adhesive flame-retardant solid polymer electrolyte.

[0062] Lithium battery cycle performance test: The battery charge and discharge range is 2.5V~4.25V, the charge and discharge rate is 0.2C, and the test temperature is 25℃. (See Table 1 and Figure 6 )

[0063] Combustion test: Cut the glass fiber into thin strips, soak it with 0.5g electrolyte component, ignite it with an open flame, and record the self-extinguishing time as 0s / g after removing the fire source. (See Table 1)

[0064] Electrochemical window test: Using the prepared electrolyte, a lithium-steel battery was assembled. Linear sweep voltammetry was used to scan from the open circuit voltage of the battery to 6V at 1mV / s, and the electrochemical window was recorded as 4.83V. (See Table 1)

[0065] Ion conductivity test: Use the prepared electrolyte to assemble a steel-to-steel battery. Measure the impedance and calculate the room temperature ionic conductivity of the electrolyte. The recorded ionic conductivity is 1.32 mS / cm. (See Table 1)

[0066] Example 5

[0067] The entire electrolyte preparation process is carried out in an argon - atmosphere glove box (H2O < 0.5 ppm, O2 < 0.5 ppm). The trimethyl phosphate solvent is dehydrated using 4A molecular sieves and set aside. Then, following the steps below: Under magnetic stirring conditions, 1.2 g of the trimethyl phosphate solvent treated by the above - mentioned dehydration method is weighed and added to a glass bottle. Then, 0.27 g of lithium bis(oxalato)borate is added under stirring conditions. After the lithium salt is completely dissolved, a phosphate - based liquid is obtained. 0.65 g of octyl cyanoacrylate is added and stirred for 30 minutes until uniformly mixed. Then, 0.05 g of ammonium persulfate is added and mixed evenly as the electrolyte component, which is set aside; Using a nine - series ternary nickel - cobalt - manganese (NCM9055) as the positive electrode, lithium metal as the negative electrode, and bacterial cellulose as the porous support material (the uniformly mixed electrolyte component is dropped onto the bacterial cellulose to make it completely infiltrated). Then, it is kept at 30 °C for 25 hours to in - situ cure the electrolyte material on the porous support material, obtaining a solid - state NCM9055 / Li lithium battery with a 10 - μm - thick highly adhesive flame - retardant solid polymer electrolyte.

[0068] Lithium - battery cycle performance test: The charge - discharge range of the battery is 2.75 V - 4.3 V, the charge - discharge rate is 1C, and the test temperature is 25 °C. (See Table 1)

[0069] Combustion test: Cut glass fibers into thin strips, soak them with 0.5 g of the electrolyte component, ignite them with an open flame, and record the self - extinguishing time as 0 s / g after removing the heat source. (See Table 1)

[0070] Electrochemical window test: Using the prepared electrolyte, assemble a lithium - on - steel battery. Using linear sweep voltammetry, scan from the open - circuit voltage of the battery to 6 V at 1 mV / s, and record the electrochemical window as 4.96 V. (See Table 1)

[0071] Ionic conductivity test: Using the prepared electrolyte, assemble a steel - on - steel battery. Measure the impedance and calculate the room - temperature ionic conductivity of the electrolyte, and record the ionic conductivity as 1.55 mS / cm. (See Table 1)

[0072] Example 6

[0073] The entire electrolyte preparation process was carried out in an argon atmosphere glove box (H2O <0.5ppm, O2 <0.5ppm). The organic trimethyl phosphate solvent was dehydrated using 4A molecular sieves and set aside. Then, the following steps were followed: Under magnetic stirring, 1.2g of trimethyl phosphate solvent treated by the above dehydration method was weighed and added to a glass bottle, and then 0.19g of lithium dioxalate borate was added under stirring. After the lithium salt was completely dissolved to obtain a phosphate base liquid, 0.78g of 2-Octyl cyanoacrylate was stirred for 30 minutes until it was evenly mixed, and then 0.02g of valerolactam was added and mixed evenly as an electrolyte component for standby use; lithium cobalt oxide was used as the positive electrode, lithium metal was used as the negative electrode, and a polyimide film was used as a porous support material (the mixed electrolyte components were dripped on the polyimide film to completely soak it), and then kept at 30°C for 16 hours to allow the electrolyte material to solidify in situ on the porous support material, thereby obtaining a 5μm thick solid-state lithium cobalt oxide / Li lithium metal battery with a highly adhesive flame-retardant solid polymer electrolyte.

[0074] Lithium battery cycle performance test: The battery charge and discharge range is 3V~4.45V, the charge and discharge rate is 0.2C, and the test temperature is 25℃. (See Table 1)

[0075] Combustion test: Cut the glass fiber into thin strips, soak it with 0.5g electrolyte component, ignite it with an open flame, and record the self-extinguishing time as 0s / g after removing the fire source. (See Table 1)

[0076] Electrochemical window test: Using the prepared electrolyte, a lithium-steel battery was assembled. Linear sweep voltammetry was used to scan from the open circuit voltage of the battery to 6V at 1mV / s, and the electrochemical window was recorded as 5.02V. (See Table 1)

[0077] Ion conductivity test: Use the prepared electrolyte to assemble a steel-to-steel battery. Measure the impedance and calculate the room temperature ionic conductivity of the electrolyte. The recorded ionic conductivity is 1.48 mS / cm. (See Table 1)

[0078] Example 7

[0079] The entire electrolyte preparation process was carried out in an argon atmosphere glove box (H2O <0.5ppm, O2 <0.5ppm). The organic trimethyl phosphate solvent was dehydrated using 4A molecular sieves and set aside. Then, the following steps were followed: Under magnetic stirring, 1.2g of trimethyl phosphate solvent treated by the above dehydration method was weighed and added to a glass bottle, and then 0.22g of lithium difluoro(1,2-dihydroxyethane-1,1,2,2-tetracyano)borate was added under stirring. After the lithium salt was completely dissolved to obtain a phosphate base liquid, 1.10g of Continue stirring 2-cyanoacrylate ethyl for 30 minutes until it is evenly mixed, then add 0.11g of azobisisoheptylnitrile, mix evenly and use it as an electrolyte component for standby use; use five-series ternary nickel cobalt manganese (NCM523) as the positive electrode, lithium metal as the negative electrode, and aramid as the porous support material (add the mixed electrolyte components onto the aramid to completely soak it), and then keep it at 30°C for 18 hours to allow the electrolyte material to solidify in situ on the porous support material, thereby obtaining a solid-state NCM523 / Li lithium metal battery with a 60μm thick, highly adhesive, flame-retardant solid polymer electrolyte.

[0080] Lithium battery cycle performance test: The battery charge and discharge range is 2.5V~4.25V, the charge and discharge rate is 0.2C, and the test temperature is 25℃. (See Table 1)

[0081] Combustion test: Cut the glass fiber into thin strips, soak it with 0.5g electrolyte component, ignite it with an open flame, and record the self-extinguishing time as 0s / g after removing the fire source. (See Table 1)

[0082] Electrochemical window test: Using the prepared electrolyte, a lithium-steel battery was assembled. Linear sweep voltammetry was used to scan from the open circuit voltage of the battery to 6V at 1mV / s, and the electrochemical window was recorded as 4.92V. (See Table 1)

[0083] Ion conductivity test: Use the prepared electrolyte to assemble a steel-to-steel battery. Measure the impedance and calculate the room temperature ionic conductivity of the electrolyte. The recorded ionic conductivity is 1.56 mS / cm. (See Table 1)

[0084] Example 8

[0085] The entire electrolyte preparation process was carried out in an argon atmosphere glove box (H2O<0.5ppm, O2<0.5ppm). The organic trimethyl phosphate solvent was dehydrated using 4A molecular sieves and set aside. Then, the following steps were followed: Under magnetic stirring, 1.2g of trimethyl phosphate solvent treated by the above dehydration method was weighed and added to a glass bottle, and then 0.40g of lithium difluoro(1,2-dihydroxyethane-1,1,2,2-tetracyano)borate was added under stirring. After the lithium salt was completely dissolved to obtain a phosphate base liquid, 0.88g of cyanoacrylic acid was added. The n-butyl ester is stirred for 30 minutes until it is evenly mixed, and then 0.03g of caprolactam is added and mixed evenly as an electrolyte component for standby use; lithium manganese oxide is used as the positive electrode, lithium metal is used as the negative electrode, and a polyethylene film with a single-sided alumina coating is used as a porous support material (the mixed electrolyte components are dripped onto the polyethylene film with a single-sided alumina coating to completely soak it), and then kept at 30°C for 10 hours to allow the electrolyte material to solidify in situ on the porous support material, thereby obtaining a solid-state lithium manganese oxide / Li lithium metal battery with a 16μm thick, highly adhesive, flame-retardant solid polymer electrolyte.

[0086] Lithium battery cycle performance test: The battery charge and discharge range is 2.5V~4.2V, the charge and discharge rate is 0.2C, and the test temperature is 25℃. (See Table 1)

[0087] Combustion test: Cut the glass fiber into thin strips, soak it with 0.5g electrolyte component, ignite it with an open flame, and record the self-extinguishing time as 0s / g after removing the fire source. (See Table 1)

[0088] Electrochemical window test: Using the prepared electrolyte, a lithium-steel battery was assembled. Linear sweep voltammetry was used to scan from the open circuit voltage of the battery to 6V at 1mV / s, and the electrochemical window was recorded as 4.92V. (See Table 1)

[0089] Ion conductivity test: Use the prepared electrolyte to assemble a steel-to-steel battery. Measure the impedance and calculate the room temperature ionic conductivity of the electrolyte. The recorded ionic conductivity is 1.62 mS / cm. (See Table 1)

[0090] Example 9

[0091] The entire electrolyte preparation process is carried out in an argon - atmosphere glove box (H2O < 0.5 ppm, O2 < 0.5 ppm). The trimethyl phosphate solvent is dehydrated using 4A molecular sieves and set aside. Then, follow the steps below: Under magnetic stirring conditions, weigh 1.2 g of the trimethyl phosphate solvent treated by the above - mentioned dehydration method and add it to a glass bottle. Then, add 0.6 g of lithium perfluorooctyl aluminate under stirring conditions. After the lithium salt is completely dissolved, a phosphate - based liquid is obtained. Add 1.1 g of alkoxy - cyanoacrylate and continue stirring for 30 minutes until evenly mixed. Then, add 0.02 g of azobisisobutyronitrile and mix evenly as the electrolyte component, set aside; Use nickel - cobalt - manganese (NCM811) of the eight - series ternary as the positive electrode, lithium metal as the negative electrode, and polyethylene film with a double - sided alumina coating as the porous support material (drop the evenly - mixed electrolyte component on the polyethylene film with a double - sided alumina coating to make it fully infiltrated). Then, keep it at 30 °C for 12 hours to in - situ cure the electrolyte material on the porous support material, obtaining a lithium manganate / Li lithium - metal battery with a 20 - μm - thick highly - adhesive flame - retardant solid polymer electrolyte.

[0092] Lithium - battery cycle performance test: The charge - discharge range of the battery is 2.5 V to 4.25 V, the charge - discharge rate is 0.2 C, and the test temperature is 25 °C. (See Table 1)

[0093] Combustion test: Cut the glass fiber into thin strips, soak them with 0.5 g of the electrolyte component, ignite them with an open flame, and record the self - extinguishing time as 0 s / g after removing the heat source. (See Table 1)

[0094] Electrochemical window test: Use the prepared electrolyte to assemble a lithium - steel battery. Using linear sweep voltammetry, scan from the open - circuit voltage of the battery to 6 V at 1 mV / s, and record the electrochemical window as 4.62 V. (See Table 1)

[0095] Ionic conductivity test: Use the prepared electrolyte to assemble a steel - steel battery. Measure the impedance and calculate the room - temperature ionic conductivity of the electrolyte, and record the ionic conductivity as 1.44 mS / cm. (See Table 1)

[0096] Example 10

[0097] The entire electrolyte preparation process was carried out in an argon - atmosphere glove box (H2O < 0.5 ppm, O2 < 0.5 ppm). The trimethyl phosphate solvent was dehydrated using 4A molecular sieves. The steps were as follows: Under magnetic stirring conditions, 1.2 g of the trimethyl phosphate solvent treated by the above - mentioned dehydration method was weighed and added to a glass bottle. Then, 1.0 g of lithium perfluorooctyl aluminate was added under stirring conditions. After the lithium salt was completely dissolved, a phosphate - based liquid was obtained. 1.1 g of octyl cyanoacrylate was added and stirred for 30 minutes until evenly mixed. Then, 0.01 g of hydrogen peroxide was added and mixed evenly as the electrolyte component for use. Using a six - series ternary nickel - cobalt - manganese (NCM622) as the positive electrode, lithium metal as the negative electrode, and a polyethylene / polypropylene composite membrane as the porous support material (the evenly - mixed electrolyte component was dropped onto the polyethylene / polypropylene composite membrane to make it fully infiltrated), and then maintained at 30 °C for 15 hours to in - situ cure the electrolyte material on the porous support material, obtaining a solid NCM622 / Li lithium - metal battery with a 12 - μm - thick highly adhesive flame - retardant solid polymer electrolyte.

[0098] Lithium - battery cycle performance test: The charge - discharge range of the battery was 2.5 V to 4.25 V, the charge - discharge rate was 0.2 C, and the test temperature was 25 °C. (See Table 1)

[0099] Combustion test: Glass fibers were cut into thin strips, infiltrated with 0.5 g of the electrolyte component, ignited with an open flame, and the self - extinguishing time was recorded as 0 s / g after removing the heat source. (See Table 1)

[0100] Electrochemical window test: Using the prepared electrolyte, a lithium - on - steel battery was assembled. Using linear sweep voltammetry, scanning from the open - circuit voltage of the battery to 6 V at 1 mV / s, the electrochemical window was recorded as 4.69 V. (See Table 1)

[0101] Ionic conductivity test: Using the prepared electrolyte, a steel - on - steel battery was assembled. The impedance was measured and the room - temperature ionic conductivity of the electrolyte was calculated, and the ionic conductivity was recorded as 1.58 mS / cm. (See Table 1)

[0102] Comparative Example 1

[0103] The entire electrolyte preparation process was carried out in an argon atmosphere glove box (H2O <0.5ppm, O2 <0.5ppm). The organic trimethyl phosphate solvent was dehydrated using 4A molecular sieves and set aside. Then, the following steps were followed: Under magnetic stirring, 1.2g of trimethyl phosphate solvent treated by the above dehydration method was weighed and added to a glass bottle, and then 0.15g of bis(fluorosulfonyl)imide lithium salt was added under stirring. After the lithium salt was completely dissolved to obtain a phosphate base liquid, 0.92g of 2-Octyl cyanoacrylate was stirred for 30 minutes until it was evenly mixed, and then 0.01 g of ammonium persulfate was added and mixed evenly as an electrolyte component for standby use; six-series ternary nickel cobalt manganese (NCM811) was used as the positive electrode, lithium metal was used as the negative electrode, and glass fiber was used as the porous support material (the mixed electrolyte components were dripped on the glass fiber to make it completely soaked), and then kept at 30°C for 20 hours to allow the electrolyte material to solidify in situ in the porous support material, thereby obtaining a solid-state NCM811 / Li lithium metal battery with a 100 μm thick, highly adhesive, flame-retardant solid polymer electrolyte.

[0104] Lithium battery cycle performance test: The battery charge and discharge range is 2.5V~4.25V, the charge and discharge rate is 0.2C, and the test temperature is 25℃. (See Table 1 and Figure 7 )

[0105] Combustion test: Cut the glass fiber into thin strips, soak it with 0.5g electrolyte component, ignite it with an open flame, and record the self-extinguishing time as 0s / g after removing the fire source. (See Table 1)

[0106] Electrochemical window test: Using the prepared electrolyte, a lithium-steel battery was assembled. Linear sweep voltammetry was used to scan from the open circuit voltage of the battery to 6V at 1mV / s, and the electrochemical window was recorded as 4.77V. (See Table 1)

[0107] Ion conductivity test: Use the prepared electrolyte to assemble a steel-to-steel battery. Measure the impedance and calculate the room temperature ionic conductivity of the electrolyte. The recorded ionic conductivity is 1.67 mS / cm. (See Table 1)

[0108] Comparative Example 2

[0109] The entire electrolyte preparation process is carried out in an argon - atmosphere glove box (H2O < 0.5 ppm, O2 < 0.5 ppm). The trimethyl phosphate solvent is dehydrated using 4A molecular sieves and set aside. Then, following the steps below: Under magnetic stirring conditions, 3 g of ethylene carbonate and 7 g of propylene carbonate are weighed and added to a glass bottle. Then, a certain mass of lithium hexafluorophosphate salt (concentration 1.0 mol / L) is added under stirring conditions. After the lithium salt is completely dissolved, stirring continues for 30 min until uniformly mixed. The uniformly - mixed solution is used as the electrolyte component and set aside; Using lithium nickel cobalt manganese oxide (NCM811) of the eight - series ternary system as the positive electrode, silicon suboxide as the negative electrode, and polypropylene membrane as the porous support material (the uniformly - mixed electrolyte component is dropped onto the polypropylene to make it fully infiltrated), and then left to stand at room temperature for 24 h until the electrolyte is fully infiltrated.

[0110] Lithium - battery cycle performance test: The charge - discharge range of the battery is 2.5 V to 4.2 V, the charge - discharge rate is 0.2 C, and the test temperature is 25 °C. (See Table 1 and Figure 10 )

[0111] Combustion test: Cut glass fibers into thin strips, soak them in 0.5 g of the electrolyte component, ignite them with an open flame, and record the self - extinguishing time as 0 s / g after removing the heat source. (See Figure 8 )

[0112] Electrochemical window test: Using the prepared electrolyte, assemble a lithium - on - steel battery. Using linear sweep voltammetry, scan from the open - circuit voltage of the battery to 6 V at 1 mV / s, and record the electrochemical window as 4.12 V. (See Figure 9 )

[0113] Ionic conductivity test: Using the prepared electrolyte, assemble a steel - on - steel battery. Measure the impedance and calculate the room - temperature ionic conductivity of the electrolyte, and record the ionic conductivity as 9.52 mS / cm. (See Table 1) Table 1

[0114]

[0115] As can be seen from the above, due to the unique molecular structure and strong adhesion characteristics of polycyanoacrylate, the high-adhesion flame-retardant solid polymer electrolyte of the present invention has extremely strong adhesion and permeability when matched with phosphate esters. It can enter the voids formed inside the solid electrode and maintain the adhesion of the positive and negative electrode interfaces well, enabling it to have extremely excellent interfacial compatibility and high adhesion characteristics with the positive and negative electrodes. It synergistically solves problems such as lithium-ion transport blockage, and can well accommodate and adapt to volume changes during long-cycle cycling of solid-state lithium batteries. Therefore, no additional device is required to provide stacking pressure. As a result, the solid polymer lithium battery without additional stacking pressure still has an extremely excellent cycle life. Furthermore, it realizes the long-cycle stable operation of the solid polymer lithium battery without additional stacking external force, solving the dilemma that conventional solid-state lithium batteries need additional pressurization to achieve stable cycling, which is beneficial to promoting the large-scale manufacture of solid-state lithium batteries. Therefore, the high-adhesion flame-retardant solid polymer electrolyte of the present invention is particularly suitable for constructing long-life solid polymer lithium metal batteries without additional stacking pressure and solid polymer lithium-ion batteries with silicon suboxide anodes. Since the constructed solid-state lithium battery does not require additional pressurization accessories, while improving safety, it can greatly increase the energy density of the solid-state lithium battery and greatly promote the development of solid-state lithium batteries. It is a very promising solid polymer electrolyte system.

[0116] The above-described embodiments only represent several implementation manners of the present invention, and their descriptions are relatively detailed and specific, but they should not be construed as limiting the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the appended claims.

Claims

1. A highly adhesive flame-retardant solid polymer electrolyte prepared by in-situ solidification, characterized in that The solid polymer electrolyte is prepared by in-situ solidification of the electrolyte components in a porous support material; wherein, the electrolyte components are intrinsically non-flammable phosphate organic solvents, lithium salts, cyanoacrylate monomers and initiators; the thickness of the solid polymer electrolyte is 3 μm - 1000 μm, the room temperature ionic conductivity is 3×10 -5 S / cm - 8×10 -3 S / cm, and the electrochemical window is ≥4.6V.

2. The highly adhesive flame-retardant solid polymer electrolyte prepared by in-situ solidification according to claim 1, wherein The electrolyte composition, by weight percentage, comprises 5%-47% lithium salt, 15-30% cyanoacrylate monomer, 0.01%-5% initiator, and the balance is an intrinsically non-flammable phosphate organic solvent; wherein, the concentration of the lithium salt is 0.3 mol / L to 1.5 mol / L in terms of the molar concentration of lithium ions.

3. The highly adhesive flame-retardant solid polymer electrolyte prepared by in-situ solidification according to claim 1 or 2, characterized in that, The intrinsically non-flammable phosphate organic solvent is trimethyl phosphate shown in Formula 1; 4. The highly adhesive flame-retardant solid polymer electrolyte prepared by in-situ solidification according to Claim 1 or 2, characterized in that The lithium salt is lithium difluorooxalate borate, lithium bis(oxalato)borate, lithium difluoro(1,2-dihydroxyethane-1,1,2,2-tetracyanato)borate or lithium perfluorooctyl aluminate; The cyanoacrylate monomer is one or more of methyl 2-cyanoacrylate, ethyl 2-cyanoacrylate, n-butyl cyanoacrylate, alkoxy cyanoacrylate, octyl cyanoacrylate and 2-octyl cyanoacrylate; The initiator is one or more of caprolactam, valerolactam, butyllithium, azobisisobutyronitrile, azobisisoheptonitrile, hydrogen peroxide, ammonium persulfate; The porous support material is one or more of polyethylene separator, polypropylene separator, polyethylene / polypropylene / polyethylene three-layer composite separator, nylon non-woven membrane, seaweed fiber non-woven membrane, cellulose non-woven membrane, bacterial cellulose, glass fiber, polyethylene terephthalate film, polyimide non-woven membrane, polyamide membrane, spandex membrane, aramid membrane, polytetrafluoroethylene separator, inorganic porous membrane.

5. A method for preparing the highly adhesive flame-retardant solid polymer electrolyte according to Claim 1, characterized in that: a) In a glove box filled with argon, the intrinsically non-flammable phosphate organic solvent is dehydrated using a molecular sieve; b) The solvent treated in step a) and the lithium salt are mixed evenly according to the above ratio, and then the cyanoacrylate monomer and the initiator are added and stirred evenly; c) The above uniformly mixed mixture is dropped onto the porous support material to make it completely infiltrated; d) The porous support material infiltrated with the mixture is left standing at 20°C - 30°C for 0.1 hrs - 30 hrs to solidify the mixture in-situ, thereby obtaining the highly adhesive flame-retardant solid polymer electrolyte.

6. Use of the highly adhesive flame-retardant solid polymer electrolyte according to claim 1, characterized in that: The application of the solid polymer electrolyte in a long-life solid polymer lithium battery without additional stacking pressure.

7. A long-life solid polymer lithium battery without additional stacking pressure, comprising a positive electrode, a negative electrode, and a solid polymer electrolyte disposed between the positive and negative electrodes, characterized in that: The solid polymer electrolyte is the highly adhesive flame-retardant solid polymer electrolyte according to Claim 1.

8. The long-life solid polymer lithium battery without additional stacking pressure according to claim 7, characterized in that: The lithium battery is assembled into a button-type battery, a steel-shell cylindrical battery, an aluminum-shell cylindrical battery, a steel-shell square battery, an aluminum-shell square battery or an aluminum-plastic film soft-pack battery.

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