Full-temperature-range polymer-based solid electrolyte, solid-state battery and preparation method

Abstract

The present invention relates to a full-temperature-range polymer-based solid electrolyte, a solid-state battery, and a preparation method. The preparation method comprises mixing an alkali metal salt, a polymer monomer, and a plasticizer to obtain an electrolyte precursor, wherein the polymer monomer comprises a fluorinated acrylate compound, and the plasticizer comprises a fluorinated carboxylate compound, a fluorinated carbonate compound, or a fluorinated amide compound; and adding an initiator to the electrolyte precursor and heating the mixture for polymerization to obtain a polymer-based solid electrolyte having a polar functional group forming a dipole group, i.e., the full-temperature-range polymer-based solid electrolyte. In the present invention, a polymer monomer having a soft long side chain is used to anchor plasticizer molecules between polymer chains, thereby reducing leakage of the plasticizer molecules and parasitic reactions between the plasticizer molecules and electrodes, thus improving the interface stability of the electrolyte in a high-temperature environment. The polar functional group in the solid electrolyte has relatively high electronegativity, and the formed dipole interacts with the alkali metal ions so that the ions are quickly decoupled from a polymer matrix, thereby improving low-temperature conductivity.

Description

A full-temperature-range polymer-based solid electrolyte, solid-state battery, and its preparation method

[0001] This application claims priority to Chinese Patent Application No. 202411615335.4, filed on November 13, 2024, entitled "A Full-Temperature Range Polymer-Based Solid Electrolyte, Solid-State Battery and Preparation Method thereof". Technical Field

[0002] This invention relates to the field of solid-state battery technology, and in particular to a full-temperature-range polymer-based solid electrolyte, a solid-state battery, and a preparation method thereof. Background Technology

[0003] With the rapid growth in demand for high-performance applications such as electric vehicles and energy storage devices, lithium batteries are finding increasingly wider applications in more complex and diverse environments. However, current carbonate-based electrolytes cannot meet the requirements of lithium batteries under harsh operating conditions. This is because their voltage window is limited to 4.3V, their operating temperature range is narrow (-20℃ to +50℃), and they are flammable. Furthermore, liquid carbonate-based electrolytes inevitably undergo parasitic reactions with metallic lithium, and the growth of lithium dendrites on the lithium anode may pose safety risks and ultimately damage the battery.

[0004] Solid electrolytes possess characteristics such as non-volatility, flame retardancy, and stability with metallic lithium, making them an effective solution for energy density and safety issues in solid-state lithium batteries. Among currently developed solid electrolytes, polymer electrolytes are considered the most promising material for solid-state battery fabrication due to their excellent flexibility, close contact with electrodes, ease of processing, and low cost. However, polymer electrolytes (e.g., polyethylene oxide (PEO)-based electrolytes) cannot achieve stable operation of solid-state batteries from low temperatures (< -20°C) to high temperatures (> +60°C), and this problem is further amplified during fast charging. This is because polymer electrolytes have low ionic conductivity, and Li... + The transport kinetics are slow, lithium deposition is uneven, and once the temperature drops below the glass transition temperature, polymer relaxation becomes very slow, and the ionic conductivity of the electrolyte decreases significantly, even approaching zero. Despite the high temperature of Li... + While the transmission rate is faster, polymer-based solid-state batteries are more prone to failure. As temperature rises, side reactions between the electrolyte and electrodes become more intense, the electrode / electrolyte interface film gradually thickens, and the "formation-degradation-reconstruction" process repeats itself, exacerbating gas production. Simultaneously, high temperatures reduce the mechanical strength of the polymer electrolyte, accelerate electrolyte aging, and lead to short-circuit risks such as direct contact between the positive and negative electrodes and dendrite growth.

[0005] Therefore, there is an urgent need to design a polymer-based solid electrolyte that meets the requirements of rapid ion conduction at low temperatures, electrolyte-electrode interface stability at high temperatures, and is applicable to the entire temperature range. Summary of the Invention

[0006] The purpose of this invention is to address the technical problems of ion transport being hindered at low temperatures (< -20℃) and electrolyte stability being insufficient at high temperatures (> +60℃) in existing polymer-based electrolytes, and to provide a full-temperature-range polymer-based solid electrolyte, solid-state battery, and preparation method, thereby obtaining a full-temperature-range polymer-based solid electrolyte and solid-state battery with an operating temperature of -40-70℃.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a full-temperature-range polymer-based solid electrolyte, comprising:

[0008] An electrolyte precursor is obtained by uniformly mixing an alkali metal salt, a polymer monomer, and a plasticizer in a specified ratio; wherein the polymer monomer includes fluorinated acrylate compounds; and the plasticizer includes one or more of fluorinated carboxylic acid ester compounds, fluorinated carbonate compounds, or fluorinated amide compounds.

[0009] An initiator is added to the electrolyte precursor and heated to polymerize, resulting in a polymer-based solid electrolyte with polar functional groups that form dipole groups, which is the full-temperature-range polymer-based solid electrolyte.

[0010] Preferably, in the electrolyte precursor, the mass ratio of the polymer monomer to the plasticizer is 1:10-10:1; and the concentration of the alkali metal salt in the electrolyte precursor is 0.5mol / L-2mol / L.

[0011] Preferably, the mass of the initiator is less than or equal to 1% of the mass of the electrolyte precursor;

[0012] The heating conditions for the heat polymerization are: heating at 45-80℃ for 0.05-24h.

[0013] Preferably, the alkali metal salt includes one or more of the following: lithium difluorooxalate borate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorodioxalate phosphate, lithium hexafluorophosphate, and sodium perchlorate, sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide.

[0014] The fluorinated acrylate compounds include one or more of the following: trifluoroethyl acrylate, hexafluoroisopropyl acrylate, pentafluoropropyl acrylate, butyl hexafluoroacrylate, heptafluorobutyl acrylate, heptafluoroisobutyl acrylate, nonafluoropentyl acrylate, tridecafluorooctyl acrylate, and dodecafluoroheptyl methacrylate.

[0015] The fluorinated carboxylic acid ester compounds include one or more of the following: methyl trifluoropropionate, methyl difluoroacetate, methyl tetrafluoropropionate, ethyl difluoroacetate, and ethyl trifluoropropionate.

[0016] The fluorinated carbonate compounds include one or more of the following: trifluoropropylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, methyl trifluoroethyl carbonate, and tetrafluoropropyl methyl carbonate.

[0017] The fluorinated amide compounds include one or more of N,N-diethyl-2,3,3,3-tetrafluoropropamide, 2,2,2-trifluoro-N,N-dimethylacetamide, and 2,3,3,3-tetrafluoropropamide.

[0018] Preferably, the polar functional group forming the dipole group includes one or more of the following: carbonyl (C=O), ether bond (COC), and fluorinated group (-F).

[0019] Secondly, embodiments of the present invention provide a full-temperature-range polymer-based solid electrolyte prepared by the preparation method described in one aspect above.

[0020] Preferably, the operating temperature range of the full-temperature-range polymer-based solid electrolyte is -40 to 70°C.

[0021] Thirdly, embodiments of the present invention provide a solid-state battery, including the full-temperature-range polymer-based solid electrolyte described in the second aspect above.

[0022] Preferably, the positive electrode active material of the solid-state battery includes one or more of the following: layered oxide, polyanionic compound, or Prussian blue compound;

[0023] The layered oxide includes one or more of lithium cobalt oxide, lithium nickel cobalt manganese oxide, and sodium nickel iron manganese oxide.

[0024] The polyanionic compound includes: lithium iron phosphate and / or sodium vanadium phosphate;

[0025] The Prussian blue compounds include: Prussian white;

[0026] The negative electrode active material includes one of graphite, lithium metal sheets, and sodium sheets.

[0027] Fourthly, embodiments of the present invention provide a method for preparing the solid-state battery described in the third aspect above, comprising:

[0028] After the polymer monomer and plasticizer are mixed evenly in a certain proportion, an alkali metal salt is added and completely dissolved to obtain an electrolyte precursor; an initiator is added to the electrolyte precursor to obtain a liquid precursor to be polymerized; wherein, the polymer monomer includes: fluorinated acrylate compounds; the plasticizer includes: one or more of fluorinated carboxylic acid ester compounds, fluorinated carbonate compounds, or fluorinated amide compounds.

[0029] The liquid precursor to be polymerized is injected into the space between the positive and negative electrodes inside the battery, so that the liquid precursor to be polymerized fully wets the positive and negative electrodes and the separator, and then the battery is encapsulated; or, the liquid precursor to be polymerized is dropped onto the positive electrode, the separator and the negative electrode, and then the battery is assembled.

[0030] The battery is polymerized under heating conditions to obtain the solid-state battery.

[0031] The method for preparing a full-temperature-range polymer-based solid electrolyte provided in this invention involves screening polymer monomers and plasticizers, optimizing precursor ratios, and utilizing an in-situ polymerization process to prepare a polymer-based solid electrolyte applicable to the entire temperature range. By using polymer monomers with flexible long side chains, plasticizer molecules can be effectively anchored between polymer chains, reducing plasticizer molecule leakage and effectively improving the thermal stability of the electrolyte. Simultaneously, it reduces parasitic reactions between plasticizer molecules and electrodes, enabling the solid-state battery to operate stably at high temperatures (>+60℃). The polymer monomers form a solid electrolyte containing polar groups after polymerization. Due to the high electronegativity of these polar functional groups, the interaction between the formed dipoles and alkali metal ions allows ions to decouple rapidly from the polymer matrix, reducing ion transport obstruction and contributing to improved conductivity at low temperatures (<-20℃). Furthermore, the flexible structure of the long-side-chain plasticizer exhibits good intermolecular freedom at low temperatures, further reducing barriers to ion migration and allowing the electrolyte to maintain high ionic conductivity even at low temperatures. The polymer-based solid electrolyte prepared by this invention exhibits good physicochemical properties and electrochemical performance in a working environment temperature range of -40 to 70°C, and its application can be extended from lithium batteries to sodium batteries, showing good application prospects. Attached Figure Description

[0032] Figure 1 is a flowchart of the preparation method of the full-temperature-range polymer-based solid electrolyte provided in the embodiment of the present invention;

[0033] Figure 2 shows the ionic conductivity-1 / T curve of the polymer-based solid electrolyte prepared in Example 1 of the present invention;

[0034] Figure 3 shows the thermal stability curve of the polymer-based solid electrolyte in Example 1 of the present invention;

[0035] Figure 4 shows the electrochemical window curves of the polymer-based solid electrolyte tested by voltammetry in Example 2 of this invention;

[0036] Figure 5 shows the battery performance of the solid-state battery assembled with the polymer-based solid electrolyte, NCM811 positive electrode, and lithium metal negative electrode prepared in Example 2 of the present invention at -40℃ to 70℃.

[0037] Figure 6 shows the battery performance of the solid-state battery assembled with the polymer-based solid electrolyte, NVP positive electrode, and sodium metal negative electrode prepared in Example 2 of the present invention at -40℃ to 70℃. Detailed Implementation

[0038] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0039] This invention provides a full-temperature-range polymer-based solid electrolyte, a solid-state battery, and a preparation method thereof.

[0040] First, the preparation method of the full-temperature-range polymer-based solid electrolyte will be described. Figure 1 is a flowchart of the preparation method of the full-temperature-range polymer-based solid electrolyte provided in the embodiment of the present invention. As shown in Figure 1, the preparation method of the full-temperature-range polymer-based solid electrolyte mainly includes the following steps:

[0041] Step 110: Mix the alkali metal salt, polymer monomer, and plasticizer in a specific ratio to obtain the electrolyte precursor.

[0042] The alkali metal salt can be a lithium salt or a sodium salt; the preferred alkali metal salts include one or more of the following: lithium difluorooxalate borate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorodioxalate phosphate, lithium hexafluorophosphate, and sodium perchlorate, sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide.

[0043] The polymer monomers include fluorinated acrylate compounds; preferred fluorinated acrylate compounds include one or more of the following: trifluoroethyl acrylate, hexafluoroisopropyl acrylate, pentafluoropropyl acrylate, butyl hexafluoroacrylate, heptafluorobutyl acrylate, heptafluoroisobutyl acrylate, nonafluoropentyl acrylate, tridefluorooctyl acrylate, and dodecafluoroheptyl methacrylate.

[0044] Plasticizers include one or more of the following: fluorinated carboxylic acid esters, fluorinated carbonates, or fluorinated amides. Fluorinated carboxylic acid esters include one or more of the following: methyl trifluoropropionate, methyl difluoroacetate, methyl tetrafluoropropionate, ethyl difluoroacetate, and ethyl trifluoropropionate; fluorinated carbonates include one or more of the following: trifluoropropylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, methyl trifluoroethyl carbonate, and tetrafluoropropyl methyl carbonate; fluorinated amides include one or more of the following: N,N-diethyl-2,3,3,3-tetrafluoropropionamide, 2,2,2-trifluoro-N,N-dimethylacetamide, and 2,3,3,3-tetrafluoropropionamide.

[0045] In the electrolyte precursor, the mass ratio of polymer monomer to plasticizer is 1:10-10:1, more preferably 1:5-1:1; the concentration of alkali metal salt in the electrolyte precursor is 0.5mol / L-2mol / L.

[0046] Optionally, functional additives such as fluoroethylene carbonate (FEC), fluoropropylene carbonate (FPC), fluoromethyl carbonate (FMC), ethylene carbonate (EC), or allyl sulfite (AES) can be added to the electrolyte precursor to help form an interfacial protective layer and improve interfacial stability.

[0047] Step 120: Add the initiator to the electrolyte precursor and heat to polymerize, to obtain a polymer-based solid electrolyte with polar functional groups that form dipole groups, which is a full-temperature-range polymer-based solid electrolyte.

[0048] The mass of the initiator is less than or equal to 1% of the mass of the electrolyte precursor;

[0049] The heating conditions for heat polymerization are: heating at 45-80℃ for 0.05-24h.

[0050] Preferably, the initiator used in this invention includes azobisisobutyronitrile (AIBN) or azobisisobutyronitrile (ABCN).

[0051] This invention prepares a polymer-based solid electrolyte applicable to the entire temperature range by screening polymer monomers and plasticizers and optimizing the precursor ratio, using an in-situ polymerization process.

[0052] By using polymer monomers with flexible long side chains, plasticizer molecules are anchored between polymer chains, reducing plasticizer leakage and effectively improving the thermal stability of the electrolyte. Simultaneously, it reduces parasitic reactions between plasticizer molecules and the electrode, improving the interfacial stability of the electrolyte at high temperatures, enabling solid-state batteries to operate stably at high temperatures (>+60°C). This invention primarily uses fluorinated carboxylic acid esters, fluorinated carbonates, or fluorinated amides as plasticizers. These compounds exhibit good ionic conductivity, withstand high voltage, and improve electrode / electrolyte interface performance. After addition, the polymer-based electrolyte exhibits good oxidation resistance, and the electrochemical window is widened to approximately 5.2V, enabling it to match high-voltage cathode materials and maintain interfacial chemical stability, thereby ensuring safety and stability under high-temperature conditions and achieving a high-safety, high-energy-density solid-state battery.

[0053] By polymerizing polymer monomers to form solid electrolytes containing polar groups, the interaction between the formed dipoles and alkali metal ions due to the high electronegativity of the polar functional groups allows for rapid decoupling of ions from the polymer matrix, reducing ion transport obstruction and improving conductivity at low temperatures (< -20℃). In this invention, the dipoles mainly originate from the polymer monomers used. After polymerization, the polymer monomers form a polymer backbone containing polar groups. Taking fluorinated acrylate compounds as an example, the polar groups include the following main components: 1. Carbonyl group (C=O): Fluorinated acrylate compounds typically contain a carbonyl group (C=O), which is polar and is retained in the polymer structure after polymerization. In the carbonyl group, carbon atoms and oxygen atoms are connected by a double bond. Oxygen has a significantly higher electronegativity than carbon, thus attracting more electron density, causing the electron cloud to shift towards oxygen, resulting in oxygen carrying a partial negative charge and carbon carrying a partial positive charge, forming a dipole; 2. Ether bond (COC): In the ether bond, the oxygen atom is located between two carbon atoms. Oxygen has high electronegativity, so it attracts electrons from its surroundings, resulting in a partially negative charge on the oxygen atom and a partially positive charge on the carbon atom bonded to it, thus forming a dipole in the COC bond. 3. Fluorinated groups (-F): Fluorine atoms themselves have high electronegativity. Fluorinated acrylates retain the structure with fluorinated groups after polymerization. These groups provide a significant dipole effect, giving the polymer a strong overall polarity. For example, when fluorine forms covalent bonds with carbon atoms (such as CF bonds), fluorine strongly attracts electrons within the covalent bond, resulting in a partially negative charge at the fluorine end and a partially positive charge at the carbon end, forming a strong dipole. After polymerization, these dipoles are distributed throughout the polymer chains of the solid electrolyte, interacting with ions and promoting ion conduction.

[0054] The polymer-based solid electrolyte prepared by this invention exhibits good physicochemical properties and electrochemical performance in a working environment temperature range of -40 to 70°C, and its application can be extended from lithium batteries to sodium batteries, showing good application prospects.

[0055] When applied to lithium-ion or sodium-ion solid-state batteries, solid-state batteries can be fabricated as follows:

[0056] Step 210: After mixing the polymer monomer and plasticizer in a certain proportion, add the alkali metal salt and dissolve it completely to obtain the electrolyte precursor; add an initiator to the electrolyte precursor to obtain the liquid precursor to be polymerized.

[0057] The materials used are the same as those used in the preparation of the polymer-based solid electrolytes mentioned above, and will not be described again.

[0058] Step 220: Inject the liquid precursor to be polymerized into the space between the positive and negative electrodes inside the battery, so that the liquid precursor to be polymerized fully wets the positive and negative electrodes and the separator, and then complete the battery encapsulation; or, drop the liquid precursor to be polymerized onto the positive electrode, the separator and the negative electrode, and then complete the battery assembly.

[0059] Step 230: Initiate polymerization of the battery under heating conditions to obtain a solid-state battery.

[0060] Those skilled in the art can refer to the following materials as needed to select the positive and negative electrode materials for solid-state batteries.

[0061] The positive electrode active material of solid-state batteries includes one or more of the following: layered oxides, polyanionic compounds, or Prussian blue compounds; wherein, the layered oxides include one or more of the following: lithium cobalt oxide, lithium nickel cobalt manganese oxide, and sodium nickel iron manganese oxide; the polyanionic compounds include: lithium iron phosphate and / or sodium vanadium phosphate; the Prussian blue compounds include: Prussian white; and the negative electrode active material includes one of the following: graphite, lithium metal sheets, and sodium sheets.

[0062] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0063] Example 1

[0064] This embodiment prepares a full-temperature-range polymer-based solid electrolyte.

[0065] Preparation of electrolyte precursor: The polymer monomer butyl hexafluoroacrylate (HFA) and plasticizer methyl trifluoropropionate (MTFP) were mixed in a mass ratio of 1:3, and then 10 wt% of additive fluoroethylene carbonate (FEC) was added. The mixture was stirred at 30°C for about 2 h. Then, lithium bisfluorosulfonyl imide (LiFSI) was added at 1 mol / L and stirred at 30°C for about 2 h until completely dissolved, finally obtaining a homogeneous electrolyte precursor.

[0066] Preparation of polymer-based solid electrolyte: 1% by mass of azobisisobutyronitrile (AIBN) was added to the electrolyte precursor obtained above, and the mixture was heated at 60°C for 2 hours to allow HFA to fully polymerize, thus obtaining the polymer-based solid electrolyte.

[0067] The polymer-based solid electrolyte was cured in a sealed electrolytic cell to facilitate ionic conductivity testing. Using a 200 μm thick copper sheet as the dual electrode, conductivity was measured at 10 °C intervals from -40 to 60 °C. The results are shown in Figure 2. It can be seen that the conductivity increases with increasing temperature. The room temperature ionic conductivity of the obtained solid electrolyte is 2.95 × 10⁻⁶. -3 Scm -1 At -40℃, the ionic conductivity can reach 0.27×10⁻⁶. -4 S cm -1 Meanwhile, as shown in Figure 3, the thermogravimetric results of this embodiment demonstrate good thermal stability, with the thermal degradation temperature increased to 155°C.

[0068] Example 2

[0069] This embodiment demonstrates the preparation of a lithium solid-state battery containing a polymer-based solid electrolyte.

[0070] Preparation of electrolyte precursor: The polymer monomer HFA and plasticizer MTFP were mixed in a mass ratio of 1:3, and then 10 wt% of additive FEC was added and stirred at 30°C for about 2 h until the mixture was homogeneous. Then, LiFSI was added at 1 mol / L and stirred at 30°C for about 2 h until completely dissolved to obtain the electrolyte precursor.

[0071] Preparation of polymer-based solid electrolyte and assembly of solid-state battery: 1% (w / w) of azobisisobutyronitrile (AIBN) was added to the electrolyte precursor obtained above to form a precursor solution; 15 μL of the obtained precursor solution was dropped onto LiNi... 0.8 Co 0.1 Mn 0.1On the O2 (NCM811) positive electrode, a polypropylene separator is placed on top, and 15 μL of precursor solution is added again to wet the separator. Then, a negative electrode lithium metal sheet, a gasket, and a spring are stacked. Finally, the assembled battery is placed in a heating device and heated at 60°C for 2 hours to allow HFA to polymerize and form a polymer-based solid electrolyte. At the same time, an integrated stack including a positive electrode, electrolyte, separator, and negative electrode is formed in situ. Finally, the battery is encapsulated to obtain a solid-state battery.

[0072] The NCM811 cathode described above was replaced with a stainless steel gasket, and the Li||SS battery for testing in this embodiment was assembled as described above, followed by linear sweep voltammetry (LSV) testing. The electrochemical window of the polymer-based solid electrolyte in this embodiment was obtained through testing, as shown in Figure 4. It can be seen that the electrochemical window of the polymer-based solid electrolyte in this embodiment reaches 5.2V.

[0073] The electrochemical performance of the solid-state battery with NCM811 cathode was characterized, and the results are shown in Figure 5. At -40℃ and a charge / discharge rate of 0.1C, the discharge specific capacity is 107 mAh / g, which can maintain 48% of its room temperature capacity; at a high temperature of 70℃, it can operate stably, and its discharge capacity is approximately 251 mAh / g.

[0074] Example 3

[0075] This embodiment demonstrates the preparation of a sodium solid-state battery containing a polymer-based solid electrolyte.

[0076] Preparation of electrolyte precursor: The polymer monomer HFA and plasticizer MTFP were mixed in a mass ratio of 1:3, and then 10 wt% of additive FEC was added and stirred at 30°C for about 2 h until the mixture was homogeneous. Then, sodium bis(fluorosulfonyl)imide was added at 1 mol / L and stirred at 30°C for about 2 h until completely dissolved to obtain the electrolyte precursor.

[0077] Preparation of polymer-based solid electrolyte and assembly of solid-state battery: 1% by mass of azobisisobutyronitrile (AIBN) was added to the electrolyte precursor obtained above to form a precursor solution; 15 μL of the obtained precursor solution was dropped onto the sodium vanadium phosphate (NVP) positive electrode, and then a polypropylene separator was placed on top. Another 15 μL of precursor solution was added to wet the separator. Then, a negative electrode lithium metal sheet, a gasket, and a spring were stacked. Finally, the assembled battery was placed in a heating device and heated at 60°C for 2 hours to allow HFA to polymerize and form a polymer-based solid electrolyte. At the same time, an integrated stack including a positive electrode, electrolyte, separator, and negative electrode was formed in situ. Finally, the battery was encapsulated to obtain a solid-state battery.

[0078] The electrochemical performance of the solid-state battery with the above-mentioned cathode as NVP was characterized, and the results are shown in Figure 6. It can be seen that the solid-state battery can still operate stably at temperatures ranging from -40℃ to 70℃, demonstrating good temperature adaptability.

[0079] Example 4

[0080] This embodiment demonstrates the preparation of a lithium solid-state battery containing a polymer-based solid electrolyte.

[0081] Preparation of electrolyte precursor: The polymer monomer HFA and plasticizer MTFP were mixed in a mass ratio of 1:2, and then 10 wt% of additive FEC was added and stirred at 30°C for about 2 h until the mixture was homogeneous. Then, LiFSI was added at 2 mol / L and stirred at 30°C for about 2 h until completely dissolved to obtain the electrolyte precursor.

[0082] Preparation of polymer-based solid electrolyte and assembly of solid-state battery: 1% by mass of azobisisobutyronitrile (AIBN) was added to the electrolyte precursor obtained above to form a precursor solution; 15 μL of the obtained precursor solution was dropped onto the NCM811 positive electrode, and then a polypropylene separator was placed on top. Another 15 μL of precursor solution was added to wet the separator. Then, a negative electrode lithium metal sheet, a gasket, and a spring were stacked. Finally, the assembled battery was placed in a heating device and heated at 60°C for 2 hours to allow HFA to polymerize and form a polymer-based solid electrolyte. At the same time, an integrated stack including a positive electrode, electrolyte, separator, and negative electrode was formed in situ. Finally, the battery was encapsulated to obtain a solid-state battery.

[0083] At -40℃ and a charge / discharge rate of 0.1C, this solid-state battery has a discharge specific capacity of 45mAh / g and can maintain 20% of its room temperature capacity. At a high temperature of 70℃, it can work stably with a discharge capacity of approximately 235mAh / g.

[0084] Example 5

[0085] This embodiment demonstrates the preparation of a lithium solid-state battery containing a polymer-based solid electrolyte.

[0086] Preparation of electrolyte precursor: The polymer monomer HFA and plasticizer MTFP were mixed in a mass ratio of 1:1, and then 10 wt% of additive FEC was added and stirred at 30°C for about 2 h until the mixture was homogeneous. Then, LiFSI was added at 2 mol / L and stirred at 30°C for about 2 h until completely dissolved to obtain the electrolyte precursor.

[0087] Preparation of polymer-based solid electrolyte and assembly of solid-state battery: 1% by mass of azobisisobutyronitrile (AIBN) was added to the electrolyte precursor obtained above to form a precursor solution; 15 μL of the obtained precursor solution was dropped onto the NCM811 positive electrode, and then a polypropylene separator was placed on top. Another 15 μL of precursor solution was added to wet the separator. Then, a negative electrode lithium metal sheet, a gasket, and a spring were stacked. Finally, the assembled battery was placed in a heating device and heated at 60°C for 2 hours to allow HFA to polymerize and form a polymer-based solid electrolyte. At the same time, an integrated stack including a positive electrode, electrolyte, separator, and negative electrode was formed in situ. Finally, the battery was encapsulated to obtain a solid-state battery.

[0088] At -40℃ and a charge / discharge rate of 0.1C, this solid-state battery has a discharge specific capacity of 20mAh / g and can maintain 9% of its room temperature capacity. At a high temperature of 70℃, it can work stably with a discharge capacity of approximately 220mAh / g.

[0089] Example 6

[0090] This embodiment demonstrates the preparation of a lithium solid-state battery containing a polymer-based solid electrolyte.

[0091] Preparation of electrolyte precursor: The polymer monomer trifluoroethyl acrylate and the plasticizer fluoroethylene carbonate were mixed in a mass ratio of 1:5, and then 10 wt% of the additive FEC was added and stirred at 30°C for about 2 h until the mixture was homogeneous. Then, lithium difluorooxalate borate was added at 2 mol / L and stirred at 30°C for about 2 h until completely dissolved to obtain the electrolyte precursor.

[0092] Preparation of polymer-based solid electrolyte and assembly of solid-state battery: 0.5% by mass of azobisisobutyronitrile (AIBN) was added to the electrolyte precursor obtained above to form a precursor solution; 15 μL of the obtained precursor solution was dropped onto the lithium cobalt oxide positive electrode, and then a polypropylene separator was placed on top of it. Another 15 μL of precursor solution was added to wet the separator. Then, a negative electrode lithium metal sheet, a gasket, and a spring were stacked. Finally, the assembled battery was placed in a heating device and heated at 45°C for 8 hours to allow trifluoroethyl acrylate to polymerize and form a polymer-based solid electrolyte. At the same time, an integrated stack including a positive electrode, electrolyte, separator, and negative electrode was formed in situ. Finally, the battery was encapsulated to obtain a solid-state battery.

[0093] Example 7

[0094] This embodiment demonstrates the preparation of a lithium solid-state battery containing a polymer-based solid electrolyte.

[0095] Preparation of electrolyte precursor: The polymer monomer tridecylfluorooctyl acrylate and the plasticizer N,N-diethyl-2,3,3,3-tetrafluoropropionamide were mixed in a mass ratio of 2:5. Then, 10 wt% of the additive FEC was added and stirred at 30°C for about 2 hours until the mixture was homogeneous. Then, lithium difluorodioxalate phosphate was added at 0.5 mol / L and stirred at 30°C for about 2 hours until completely dissolved to obtain the electrolyte precursor.

[0096] Preparation of polymer-based solid electrolyte and assembly of solid-state battery: 0.2% by mass of azobisisobutyronitrile (AIBN) was added to the electrolyte precursor obtained above to form a precursor solution; 15 μL of the obtained precursor solution was dropped onto the lithium cobalt oxide positive electrode, and then a polypropylene separator was placed on top of it. Another 15 μL of precursor solution was added to wet the separator. Then, a negative electrode lithium metal sheet, a gasket, and a spring were stacked. Finally, the assembled battery was placed in a heating device and heated at 80°C for 2 hours to allow tridecylfluorooctyl acrylate to undergo a polymerization reaction to form a polymer-based solid electrolyte. At the same time, an integrated stack including a positive electrode, electrolyte, separator, and negative electrode was formed in situ. Finally, the battery was encapsulated to obtain a solid-state battery.

[0097] This invention utilizes an in-situ polymerization process to prepare a polymer-based solid electrolyte suitable for the entire temperature range by screening polymer monomers and plasticizers and optimizing precursor ratios. The polymer-based solid electrolyte prepared by this invention exhibits excellent physicochemical properties and electrochemical performance within an operating temperature range of -40 to 70°C, and can be applied to lithium-ion and sodium-ion batteries, showing promising application prospects.

[0098] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a full-temperature-range polymer-based solid electrolyte, characterized in that, The preparation method includes: An electrolyte precursor is obtained by uniformly mixing an alkali metal salt, a polymer monomer, and a plasticizer in a specified ratio; wherein the polymer monomer includes fluorinated acrylate compounds; and the plasticizer includes one or more of fluorinated carboxylic acid ester compounds, fluorinated carbonate compounds, or fluorinated amide compounds. An initiator is added to the electrolyte precursor and heated to polymerize, resulting in a polymer-based solid electrolyte with polar functional groups that form dipole groups, which is the full-temperature-range polymer-based solid electrolyte.

2. The preparation method according to claim 1, characterized in that, In the electrolyte precursor, the mass ratio of the polymer monomer to the plasticizer is 1:10-10:1; the concentration of the alkali metal salt in the electrolyte precursor is 0.5mol / L-2mol / L.

3. The preparation method according to claim 1, characterized in that, The mass of the initiator is less than or equal to 1% of the mass of the electrolyte precursor; The heating conditions for the heat polymerization are: heating at 45-80℃ for 0.05-24h.

4. The preparation method according to claim 1, characterized in that, The alkali metal salts include one or more of the following: lithium difluorooxalate borate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorodioxalate phosphate, lithium hexafluorophosphate, and sodium perchlorate, sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide. The fluorinated acrylate compounds include one or more of the following: trifluoroethyl acrylate, hexafluoroisopropyl acrylate, pentafluoropropyl acrylate, butyl hexafluoroacrylate, heptafluorobutyl acrylate, heptafluoroisobutyl acrylate, nonafluoropentyl acrylate, tridecafluorooctyl acrylate, and dodecafluoroheptyl methacrylate. The fluorinated carboxylic acid ester compounds include one or more of the following: methyl trifluoropropionate, methyl difluoroacetate, methyl tetrafluoropropionate, ethyl difluoroacetate, and ethyl trifluoropropionate. The fluorinated carbonate compounds include one or more of the following: trifluoropropylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, methyl trifluoroethyl carbonate, and tetrafluoropropyl methyl carbonate. The fluorinated amide compounds include one or more of N,N-diethyl-2,3,3,3-tetrafluoropropamide, 2,2,2-trifluoro-N,N-dimethylacetamide, and 2,3,3,3-tetrafluoropropamide.

5. The preparation method according to claim 1, characterized in that, The polar functional groups that form the dipole groups include one or more of the following: carbonyl (C=O), ether (COC), and fluorinated groups (-F).

6. A full-temperature-range polymer-based solid electrolyte prepared by any of the preparation methods described in claims 1-5.

7. The full-temperature-range polymer-based solid electrolyte according to claim 6, characterized in that, The operating temperature range of the full-temperature-range polymer-based solid electrolyte is -40 to 70°C.

8. A solid-state battery, characterized in that, The solid-state battery includes the full-temperature-range polymer-based solid electrolyte as described in claim 6.

9. The solid-state battery according to claim 8, characterized in that, The positive electrode active material of the solid-state battery includes one or more of the following: layered oxide, polyanionic compound, or Prussian blue compound; The layered oxide includes one or more of lithium cobalt oxide, lithium nickel cobalt manganese oxide, and sodium nickel iron manganese oxide. The polyanionic compound includes: lithium iron phosphate and / or sodium vanadium phosphate; The Prussian blue compounds include: Prussian white; The negative electrode active material includes one of graphite, lithium metal sheets, and sodium sheets.

10. A method for preparing a solid-state battery according to claim 8, characterized in that, The preparation method includes: After the polymer monomer and plasticizer are mixed evenly in a certain proportion, an alkali metal salt is added and completely dissolved to obtain an electrolyte precursor; an initiator is added to the electrolyte precursor to obtain a liquid precursor to be polymerized; wherein, the polymer monomer includes: fluorinated acrylate compounds; the plasticizer includes: one or more of fluorinated carboxylic acid ester compounds, fluorinated carbonate compounds, or fluorinated amide compounds. The liquid precursor to be polymerized is injected into the space between the positive and negative electrodes inside the battery, so that the liquid precursor to be polymerized fully wets the positive and negative electrodes and the separator, and then the battery is encapsulated; or, the liquid precursor to be polymerized is dropped onto the positive electrode, the separator and the negative electrode, and then the battery is assembled. The battery is polymerized under heating conditions to obtain the solid-state battery.

Images