An in-situ solid-state battery and a method of manufacturing the same

Abstract

This invention provides an in-situ solid-state battery and its preparation method, comprising a battery cell and an in-situ solidified electrolyte precursor injected into the battery cell. The in-situ solidified electrolyte precursor is formulated according to the following mass percentages: 1-30 wt.% polymeric monomer, 0.1-1 wt.% initiator, 10-20 wt.% lithium salt, 0.1-10 wt.% redox shuttle, and the balance being an organic solvent. This invention utilizes the redox shuttle to react within the battery, converting electrical energy into heat, thereby uniformly heating the battery interior and solidifying the gel electrolyte in situ. This method provides more uniform heating and a more uniform polymerization effect, resulting in a more uniform and stable battery interface and higher cycle stability, thus producing a high-performance solid-state battery. Furthermore, this method is applicable to most polymeric monomers and achieves uniform heating within the battery without adding additional equipment.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion batteries, and more particularly to an in-situ solid-state battery and its preparation method. Background Technology

[0002] Lithium-ion batteries are widely used in electric vehicles, energy storage, and 3C products due to their high energy density, high voltage platform, and long cycle life. Currently, improving battery energy density and safety are the two core development directions in the industry. Electrolytes, represented by carbonate-based organic solvents, have achieved success in commercial applications, but their safety issues, such as easy leakage, volatility, and flammability, make the development of solid-state electrolytes particularly urgent. Solid-state electrolytes can not only significantly improve battery safety but also are compatible with lithium metal anodes, thereby greatly increasing battery energy density. Solid-state electrolytes are mainly divided into inorganic solid-state electrolytes and polymer solid-state electrolytes. Inorganic solid-state electrolytes have high ionic conductivity, a wide electrochemical window, and excellent mechanical strength; however, insufficient interfacial stability between the electrode and electrolyte, high processing difficulty, and high cost limit their further development. Polymer solid-state electrolytes have received widespread attention from the industry due to their simple processing technology and good interfacial compatibility. The non-in-situ preparation of polymer electrolytes involves externally prepared electrolyte membranes used in battery assembly. However, because the polymer electrolyte only contacts the electrode surface, the contact is not tight, resulting in low utilization of active materials and poor battery cycle performance. In-situ polymerization, on the other hand, uses a precursor solution as the electrolyte in a liquid battery. The battery is assembled according to liquid battery assembly methods. After battery encapsulation, the precursor solution is polymerized under specific conditions to obtain the polymer electrolyte. Compared to non-in-situ methods, in-situ polymerization offers advantages such as the ability of the liquid precursor to wet the positive electrode pores, facilitating the construction of a good electrode / electrolyte interface and better ion conduction in the positive electrode. Furthermore, this method is well-compatible with existing battery manufacturing processes and has promising application prospects.

[0003] In-situ polymerization of solid electrolytes involves mixing monomers, initiators, and electrolytes to form an electrolyte precursor solution. Under specific external conditions (such as thermal initiation or photoinitiation), monomer molecules polymerize in situ to obtain a polymer electrolyte capable of conducting lithium ions. Since ultraviolet light cannot penetrate outer casings such as aluminum-plastic films, photoinitiation cannot be applied to in-situ polymerization at the cell level. Therefore, thermal initiation is the most suitable polymerization method. Thermal initiation primarily uses heat conduction to heat the battery for polymerization. The outer side of the cell heats up first, and then the heat is conducted to the inside of the cell, resulting in an uneven thermal field distribution inside and outside the cell. This leads to uneven curing during thermal initiation.

[0004] Chinese patent CN116404259A discloses a method for heating a battery cell containing an in-situ solidified electrolyte precursor using pulsed current. This method utilizes the battery's internal impedance to achieve uniform heating within the cell, resulting in a more uniform polymerization effect. However, this method requires additional pulsed charging and discharging equipment, leading to additional production costs.

[0005] Chinese patent CN116093426A discloses a method for preparing an electropolymerized gel electrolyte battery that does not require the addition of an initiator, thus avoiding the adverse effects of an additional initiator on battery performance. However, the electrochemically initiated polymerization product coats the electrode surface, and the poor conductivity of the polymerization product leads to incomplete polymerization of subsequent monomers.

[0006] To address this issue, we propose an in-situ solid-state battery and its preparation method, which improves the uniformity of the in-situ solidified polymer electrolyte by simplifying the curing process. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art. To achieve the above objective, this invention adopts the following technical solution: An in-situ solid-state battery includes a cell and an in-situ solidified electrolyte precursor injected into the cell. The in-situ solidified electrolyte precursor is formulated according to the following mass percentages: 1-30 wt.% polymerizable monomer, 0.1-1 wt.% initiator, 10-20 wt.% lithium salt, 0.1-10 wt.% redox shuttle, and the balance being an organic solvent. This invention achieves uniform in-situ polymerization by adding a redox shuttle to the in-situ solidified electrolyte precursor and utilizing the redox reaction of the redox shuttle to convert electrical energy into heat energy, thereby internally heating the battery to be solidified.

[0008] More preferably, the polymerizable monomer includes one or more combinations of monomers that do not contain unsaturated carbon-carbon double bonds; cyclic monomers that can undergo ring-opening polymerization; and monomers that contain polymerizable active functional groups.

[0009] Further preferably, the redox shuttle includes 2,5-di-tert-butyl-1,4-bis(2-methoxyethoxy)benzene, 2,5-di-tert-butyl-1,4-bis(methoxy)benzene, 2,5-di-tert-butyl-1,4-bis(2,2,2-trifluoroethoxy)benzene, 2,5-di-tert-butyl-1,4-bis(2,2,3,3-tetrafluoropropoxy)benzene, 2,5-di-tert-butyl-1,4-bis(4,4,4,3,2,2-hexafluorobutoxy)benzene, 2,7-diacetylthiathanthracene, 2,7-dibromothiathanthracene, 2,7-diisobutyrylthiathanthracene, 2-acetylthiathanthracene, 2,5-difluoro-1,4-dimethoxybenzene, and 2-(pentafluorophenyl)-tetrafluoro-1,3 The following are combinations of one or more of the following: 2-benzodioxoborane, Li2B12F12, tetraethyl-2,5-di-tert-butyl-1,4-phenylene diphosphonic acid, 1,4-bis[bis(1-methylethyl)oxophosphonyl]-2,5-dimethoxybenzene, 1,4-bis[bis(1-methyl)oxophosphonyl]-2,5-difluoro-3,6-dimethoxybenzene, pentafluorophenyl-tetrafluorobenzyl-1,2-dioxaborone, ferrocene and its derivatives, phenothiazine derivatives, N,N-dialkyl-dihydrophenazine, 2,2,6,6-tetramethylpiperidine oxide, Li2B12H12-xFx (x = 9 and 12), and lithium iodide (LiI).

[0010] More preferably, the initiator includes one or more combinations of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl, diisopropylbenzene peroxide, dibenzoyl peroxide, and ammonium persulfate.

[0011] More preferably, the battery cell is formed by winding or stacking positive electrode plates, negative electrode plates, and a separator placed between the positive electrode plates and the negative electrode plates.

[0012] More preferably, the positive electrode sheet is one or more composites of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel oxide, lithium iron phosphate, and lithium vanadium phosphate.

[0013] More preferably, the negative electrode sheet is one or more composite materials including carbon materials, silicon materials, silicon-carbon composite materials, silicon oxide materials, tin-based materials, lithium titanate, etc.

[0014] A method for preparing an in-situ solid-state battery includes the following steps: S1: Mix the polymer monomer, initiator, organic solvent, lithium salt and redox shuttle additive in proportion to obtain the in-situ solidified electrolyte precursor; S2: Inject the in-situ cured electrolyte precursor into the cell and let it stand for a period of time to obtain the battery to be cured; S3: The battery to be cured is subjected to heat insulation treatment, and the battery to be cured is charged with constant current. After reaching the self-balancing voltage, when the internal temperature of the battery to be cured rises to a certain temperature, the in-situ cured electrolyte precursor is heated and cured to obtain a semi-solid battery.

[0015] More preferably, the settling time mentioned in S2 is 6h~72h.

[0016] More preferably, in S3, the self-balancing start-up voltage is 3.8~4.9V; and the self-balancing current is 0.1~10A.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes a redox shuttle to react within the battery, converting electrical energy into heat. This uniform heating of the battery interior facilitates in-situ solidification of the gel electrolyte. This method results in more uniform heating and a more uniform polymerization effect, leading to a more homogeneous and stable battery interface and higher cycle stability, thus enabling the fabrication of high-performance solid-state batteries. Furthermore, this method is applicable to most polymerizable monomers, achieving uniform heating within the battery without the need for additional equipment. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart of the preparation method of the present invention; Figure 2 This is a schematic diagram illustrating the heating and curing process using a redox shuttle reaction, as described in this invention. Figure 3 Photo of the battery disassembly interface for Comparative Example 1; Figure 4 Photo of the battery disassembly interface for Comparative Example 2; Figure 5 This is a photograph of the battery disassembly interface in Example 1; Figure 6 The graph shows the battery capacity retention rate versus cycle count for Comparative Example 1, Comparative Example 2, and Example 1. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0020] Reference Figures 1-2 An in-situ solid-state battery includes a battery cell and an in-situ solidified electrolyte precursor injected into the battery cell, wherein the in-situ solidified electrolyte precursor is formulated in the following mass percentages. The composition includes 1-30 wt.% monomer, 0.1-1 wt.% initiator, 10-20 wt.% lithium salt, 0.1-10 wt.% redox shuttle, and the balance being organic solvent.

[0021] The polymerizable monomers include monomers without unsaturated carbon-carbon double bonds; cyclic monomers capable of ring-opening polymerization; and combinations of one or more monomers containing polymerizable active functional groups. The redox shuttle includes 2,5-di-tert-butyl-1,4-bis(2-methoxyethoxy)benzene (DBBB), 2,5-di-tert-butyl-1,4-bis(methoxy)benzene (DDB), 2,5-di-tert-butyl-1,4-bis(2,2,2-trifluoroethoxy)benzene (DBDFB), 2,5-di-tert-butyl-1,4-bis(2,2,3,3-tetrafluoropropoxy)benzene (DBTFP), 2,5-di-tert-butyl-1,4-bis(4,4,4,3,2,2-hexafluorobutoxy)benzene (DBHFB), 2,7-diacetylthiaanthracene, 2,7-dibromothiaanthracene, and 2... 7-Diisobutyrylthiaanthracene, 2-acetylthiaanthracene, 2,5-difluoro-1,4-dimethoxybenzene (DFDB), 2-(pentafluorophenyl)-tetrafluoro-1,3,2-benzodioxoborane, Li2B12F12, tetraethyl-2,5-di-tert-butyl-1,4-phenylene diphosphonic acid (TEDBPDP), 1,4-bis[bis(1-methylethyl)oxyphosphono]-2,5-dimethoxybenzene (BPDB), 1,4-bis[bis(1-methyl)oxyphosphono]-2,5-difluoro-3,6-dimethoxybenzene (BPDFDB), pentafluorophenyl-tetrafluorobenzyl-1,2-dioxaborone (PFPTFBDB), ferrocene and its derivatives, phenothiazine derivatives, N The initiator comprises one or more combinations of N-dialkyl-dihydrophenazine, 2,2,6,6-tetramethylpiperidine oxide (TEMPO), Li₂B₁₂H₁₂-xFₓ (x = 9 and 12), and lithium iodide (LiI); the initiator comprises one or more combinations of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl, dicumyl peroxide, benzoyl peroxide, and ammonium persulfate.

[0022] The battery cell is formed by winding or stacking positive electrode plates, negative electrode plates, and a separator placed between the positive and negative electrode plates; the positive electrode plate is one or more composites of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel oxide, lithium iron phosphate, lithium vanadium phosphate, etc.; the negative electrode plate is one or more composites of carbon materials, silicon materials, silicon-carbon composite materials, silicon oxide materials, tin-based materials, lithium titanate, etc.

[0023] A method for preparing an in-situ solid-state battery includes the following steps: S1: Mix the polymer monomer, initiator, organic solvent, lithium salt and redox shuttle additive in proportion to obtain the in-situ solidified electrolyte precursor; S2: Inject the in-situ cured electrolyte precursor into the cell and let it stand for a period of time, the standing time being 6h~72h, to obtain the battery to be cured; S3: The battery to be cured is subjected to heat insulation treatment to avoid heat loss generated by the redox shuttle. The battery to be cured in S2 is charged with constant current until the self-balancing voltage is reached. The self-balancing start voltage is 3.8~4.9V and the self-balancing current is 0.1~10A. This raises the internal temperature of the cell. When a certain temperature is reached, the in-situ solidified electrolyte precursor is heated and cured to obtain a semi-solid battery.

[0024] Comparative Example 1 (1) The positive electrode active material lithium nickel cobalt manganese oxide (NCM622), conductive carbon black and polyvinylidene fluoride are mixed in a mass ratio of 96:2:2. After the mixture is completed, N-methylpyrrolidone (NMP) is added and the mixture is stirred and mixed thoroughly to obtain a positive electrode slurry. The slurry is then uniformly coated on aluminum foil and dried to obtain a positive electrode sheet.

[0025] (2) The NCM622 positive electrode, lithium metal negative electrode, and separator are sequentially stacked, tab welded, and top-side sealed to obtain the battery to be injected with liquid.

[0026] (3) Preparation of electrolyte: Ethylene carbonate (EC) and dimethyl carbonate (DMC) are mixed in a mass ratio of EC:DMC=3:7 and 2wt.% vinylene carbonate (VC) to obtain an organic solvent. Lithium hexafluorophosphate is then added to the organic solvent. After the lithium hexafluorophosphate is completely dissolved, the electrolyte is obtained. The mass fractions of lithium hexafluorophosphate and organic solvent are 15% and 85%, respectively.

[0027] (4) Inject the electrolyte prepared in (3) into the battery to be injected, seal it, and let it stand for 24 hours (at 25°C) to form and divide the capacity.

[0028] (5) Disassemble the battery after it has been processed and tested in (4), and observe the battery interface as follows. Figure 3 As shown, the battery after being converted and tested in (4) was subjected to cycle performance testing.

[0029] Comparative Example 2 (1) The positive electrode active material lithium nickel cobalt manganese oxide (NCM622), conductive carbon black and polyvinylidene fluoride are mixed in a mass ratio of 96:2:2. After the mixture is completed, N-methylpyrrolidone (NMP) is added and the mixture is stirred and mixed thoroughly to obtain a positive electrode slurry. The slurry is then uniformly coated on aluminum foil and dried to obtain a positive electrode sheet.

[0030] (2) The NCM622 positive electrode, lithium metal negative electrode, and separator are sequentially stacked, tab welded, and top-side sealed to obtain the battery to be injected with liquid.

[0031] (3) Preparation of in-situ cured gel electrolyte precursor: Ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed at a mass ratio of EC:DMC=3:7 and 2wt.% vinylene carbonate (VC) to obtain an organic solvent. Lithium hexafluorophosphate was then added to the organic solvent. After the lithium hexafluorophosphate was completely dissolved, an electrolyte was obtained. Methyl methacrylate and azobisisobutyronitrile were then added to the electrolyte and mixed evenly to obtain the in-situ cured gel electrolyte precursor. The mass fractions of lithium hexafluorophosphate, organic solvent, methyl methacrylate, and azobisisobutyronitrile were 15%, 64.9%, 20%, and 0.1%, respectively.

[0032] (4) Inject the electrolyte prepared in (3) into the battery to be injected, seal it, and let it stand for 24 hours (at 25°C) to obtain the battery to be cured.

[0033] (5) Place the battery to be cured in (4) in an oven and heat it at 60°C for 12 hours to obtain a semi-solid battery.

[0034] (6) The semi-solid battery in (5) is subjected to capacity testing and disassembly. The battery interface is observed as follows: Figure 4 As shown, the battery after formation and capacity testing was also subjected to cycle performance testing. Example

[0035] (1) The positive electrode active material lithium nickel cobalt manganese oxide (NCM622), conductive carbon black and polyvinylidene fluoride are mixed in a mass ratio of 96:2:2. After the mixture is completed, N-methylpyrrolidone (NMP) is added and the mixture is stirred and mixed thoroughly to obtain a positive electrode slurry. The slurry is then uniformly coated on aluminum foil and dried to obtain a positive electrode sheet.

[0036] (2) The NCM622 positive electrode, lithium metal negative electrode, and separator are sequentially stacked, tab welded, and top-side sealed to obtain the battery to be injected with liquid.

[0037] (3) Preparation of in-situ cured gel electrolyte precursor: Ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed at a mass ratio of EC:DMC=3:7, and 2wt.% vinylene carbonate (VC) to obtain an organic solvent. Lithium hexafluorophosphate was then added to the organic solvent. After the lithium hexafluorophosphate was completely dissolved, an electrolyte was obtained. Methyl methacrylate, azobisisobutyronitrile and 2,2,6,6-tetramethylpiperidine oxide (TEMPO) were then added to the electrolyte and mixed evenly to obtain the in-situ cured gel electrolyte precursor. The mass fractions of lithium hexafluorophosphate, organic solvent, methyl methacrylate, azobisisobutyronitrile and TEMPO were 15%, 59.9%, 20%, 0.1% and 5%, respectively.

[0038] (4) Inject the electrolyte prepared in (3) into the battery to be injected, seal it, and let it stand for 24 hours (at 25°C) to obtain the battery to be cured.

[0039] (5) The battery to be cured in (4) was heat-insulated with heat-insulating material and charged with constant current for 24 hours. The current was 0.4A and the voltage was stable at 3.52V, indicating that the redox shuttle reaction was in progress, converting electrical energy into heat energy, causing the internal temperature of the battery to rise. When a certain temperature was reached, in-situ polymerization was carried out to obtain a semi-solid battery.

[0040] (6) The semi-solid battery in (5) is subjected to capacity testing and disassembly. The battery interface is observed as follows: Figure 5 As shown, the battery after formation and capacity testing was also subjected to cycle performance testing.

[0041] By comparison Figure 3 , Figure 4 and Figure 5 It can be observed that in Comparative Example 1, most of the lithium powder generated during the formation and capacity testing of the lithium metal battery adheres to the surface of the separator. In Comparative Example 2 and Example 1, which are solidified in situ, most of the lithium powder is distributed on the surface of the negative electrode. Furthermore, Example 1, which uses redox shuttle heating, can obtain a more uniform and stable battery interface compared to Comparative Example 2, which uses oven heating.

[0042] from Figure 6 The cycling data show that the electrolyte has better cycling performance than the in-situ solidified electrolyte. This is because the gel electrolyte after in-situ solidification affects the transport of lithium ions kinetically, resulting in weaker cycling performance than the electrolyte group in Comparative Example 1. The in-situ solidified gel battery (Example 1) heated by redox shuttle effect has a higher capacity retention rate after 150 cycles at 0.33C, which is better than the in-situ solidified gel battery heated by oven heating (Comparative Example 2). This indicates that the redox shuttle effect heating method can form a more uniform electrode-electrolyte interface, which is beneficial to performance improvement.

[0043] This invention adds a redox shuttle to the in-situ solidified electrolyte precursor and uses the redox reaction of the redox shuttle to convert electrical energy into heat energy, thereby heating the inside of the cell of the battery to be solidified and achieving uniform in-situ polymerization.

[0044] This invention utilizes a redox shuttle to react within the battery, converting electrical energy into heat. This uniform heating of the battery interior facilitates in-situ solidification of the gel electrolyte. This method results in more uniform heating and a more uniform polymerization effect, leading to a more homogeneous and stable battery interface and higher cycle stability, thus enabling the fabrication of high-performance solid-state batteries. Furthermore, this method is applicable to most polymerizable monomers, achieving uniform heating within the battery without the need for additional equipment.

Claims

1. An in situ solid state battery, characterized by, It includes a battery cell and an in-situ cured electrolyte precursor injected into the battery cell, wherein the in-situ cured electrolyte precursor is formulated according to the following mass percentages. The composition includes 1-30 wt.% monomer, 0.1-1 wt.% initiator, 10-20 wt.% lithium salt, 0.1-10 wt.% redox shuttle, and the balance being organic solvent.

2. An in situ solid state battery according to claim 1, wherein, The polymerizable monomers include monomers that do not contain unsaturated carbon-carbon double bonds; cyclic monomers that can undergo ring-opening polymerization; and one or more combinations of monomers containing polymerizable reactive functional groups.

3. An in situ solid state battery according to claim 2, wherein, The redox shuttle includes 2,5-di-tert-butyl-1,4-bis(2-methoxyethoxy)benzene, 2,5-di-tert-butyl-1,4-bis(methoxy)benzene, 2,5-di-tert-butyl-1,4-bis(2,2,2-trifluoroethoxy)benzene, 2,5-di-tert-butyl-1,4-bis(2,2,3,3-tetrafluoropropoxy)benzene, 2,5-di-tert-butyl-1,4-bis(4,4,4,3,2,2-hexafluorobutoxy)benzene, 2,7-diacetylthiathanthracene, 2,7-dibromothiathanthracene, 2,7-diisobutyrylthiathanthracene, 2-acetylthiathanthracene, 2,5-difluoro-1,4-dimethoxybenzene, and 2-(pentafluorophenyl)-tetrafluoro-1,3 ,2-Benzoborane, Li2B12F12, tetraethyl-2,5-di-tert-butyl-1,4-phenylene diphosphonic acid, 1,4-bis[bis(1-methylethyl)oxyphosphonyl]-2,5-dimethoxybenzene, 1,4-bis[bis(1-methyl)oxyphosphonyl]-2,5-difluoro-3,6-dimethoxybenzene, pentafluorophenyl-tetrafluorobenzyl-1,2-dioxaborone, ferrocene and its derivatives, phenothiazine derivatives, N,N-dialkyl-dihydrophenazine, 2,2,6,6-tetramethylpiperidine oxide, Li2B12H12-xFx (x = 9 and 12) and lithium iodide, or one or more combinations thereof.

4. An in situ solid state battery according to claim 3, wherein, The initiator includes one or more combinations of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl, diisopropylbenzene peroxide, dibenzoyl peroxide, and ammonium persulfate.

5. An in situ solid state battery according to claim 1, wherein, The battery cell consists of a positive electrode, a negative electrode, and a separator placed between the positive and negative electrode, which are obtained by winding or stacking.

6. An in situ solid state battery according to claim 5, wherein, The positive electrode is one or more composites of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel oxide, lithium iron phosphate, and lithium vanadium phosphate.

7. An in situ solid state battery according to claim 5, wherein, The negative electrode sheet is one or more composite materials including carbon materials, silicon materials, silicon-carbon composite materials, silicon oxide materials, tin-based materials, lithium titanate, etc.

8. A method of making an in situ solid state battery, characterized by, Includes the following steps: S1: Mix the polymer monomer, initiator, organic solvent, lithium salt and redox shuttle additive in proportion to obtain the in-situ solidified electrolyte precursor; S2: Inject the in-situ cured electrolyte precursor into the cell and let it stand for a period of time to obtain the battery to be cured; S3: The battery to be cured is subjected to heat insulation treatment, and the battery to be cured is charged with constant current. After reaching the self-balancing voltage, when the internal temperature of the battery to be cured rises to a certain temperature, the in-situ cured electrolyte precursor is heated and cured to obtain a semi-solid battery.

9. The method of claim 8, wherein the method further comprises, The settling time mentioned in S2 is 6h~72h.

10. The method of claim 8, wherein the method further comprises, In S3, the self-balancing start-up voltage is 3.8~4.9V; the self-balancing current is 0.1~10A.

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