Precursor solution, quasi-solid electrolyte and preparation method and application of quasi-solid electrolyte

Abstract

The invention discloses a precursor solution. The precursor solution comprises a carbonic ester solvent, a sulfate ester solvent and a conductive lithium salt, the addition amount of the sulfate solvent is 0.01-1vol% of the carbonate solvent, and the sulfate solvent and the carbonate solvent are used as a solvent system of the precursor solution; the concentration of the conductive lithium salt in the solvent system is 0.5 mol / L-5 mol / L; the method further comprises the step of adding an initiator or a catalyst, wherein the adding amount of the initiator or the catalyst in the solvent system is 0.1 mmol / L-1 mol / L; the precursor solution can be directly polymerized to prepare a quasi-solid electrolyte, has a high lithium ion transference number (greater than 0.8) and a very wide electrochemical stability window (greater than or equal to 5.4 V vs.Li < + > / Li), has excellent cycle performance under the conditions of high voltage of 4.5 V and large multiplying power of 2C, can stably work for a long time at room temperature, and even can normally work in a low-temperature environment of-30 DEG C; the invention also discloses a preparation method and application of the precursor solution and the quasi-solid electrolyte.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery electrolytes, and particularly relates to a precursor solution, a quasi-solid electrolyte and their applications. Background Art

[0002] With the continuous growth of global energy demand and the increasing awareness of environmental protection, high-performance battery technologies are increasingly widely used in fields such as electric vehicles, portable electronic devices, and large-scale energy storage systems. Among them, lithium-ion batteries have become one of the most promising electrochemical energy storage technologies due to their high energy density, long cycle life, and low self-discharge rate.

[0003] The current technological development trends of high voltage, high rate, and wide temperature range of lithium-ion batteries are in irreconcilable performance contradictions with traditional electrolyte systems. The specific analysis is as follows:

[0004] In high-voltage scenarios (>4.5V), carbonate solvents are prone to violent decomposition due to insufficient antioxidant ability, which not only causes gas production and expansion but also destroys the stability of the electrode interface. In this field, high-voltage additives are generally added to delay the decomposition of carbonate solvents, but new technical problems will arise, namely the formation of a dense passivation layer, which seriously hinders lithium-ion transport.

[0005] In low-temperature environments (-30°C), the viscosity of the electrolyte will rise sharply, resulting in a sharp drop in ionic conductivity. Although the low-temperature fluidity of the electrolyte can be improved by introducing low-freezing-point solvents, such as the electrolyte of an aqueous zinc-iodine battery disclosed in the patent document with publication number CN119542573A, which is prepared from a stabilizer, a hydrogen bond ligand, a low-freezing-point hydrogen donor solvent, and a zinc salt, low-freezing-point solvents tend to cause side reactions under high-voltage or high-current operating conditions, resulting in accelerated capacity decay.

[0006] For high-current demands (above 2C), the existing liquid electrolytes suffer from aggravated concentration polarization due to interface kinetic hysteresis, while solid electrolytes, although able to inhibit dendrite growth, cannot be practical due to the too-high solid-solid contact impedance with the electrodes. The in-situ polymerization technology developed in recent years attempts to balance liquid wettability and solid stability, but traditional thermal-initiated polymerization requires high-temperature conditions, which easily causes solvent volatilization and electrode structure damage, and the polymerization products are too rigid to adapt to the volume changes during charge and discharge processes.

[0007] The essence of the above technical problems lies in that the existing electrolytes or solid electrolytes cannot simultaneously meet: ① the dynamic stable construction of the high-voltage interface; ② the efficient conduction channel for low-temperature ions; ③ the rapid charge transfer under high current. Therefore, lithium-ion batteries containing electrolytes often have difficulty in maintaining normal operation when facing high voltage, high current, or extreme temperature conditions, and solid electrolyte technology also has many limitations in achieving high voltage, high current, and low-temperature adaptability, making it difficult to meet the actual application requirements.

[0008] In summary, the present invention aims to develop an electrolyte material with voltage tolerance, temperature adaptability, and interfacial compatibility, so that a lithium battery containing the electrolyte material can operate stably under harsh conditions. Summary of the Invention

[0009] In view of the problems in the related art, the present invention provides a precursor solution, a quasi-solid electrolyte, and their applications to overcome the above technical problems existing in the prior art. The prepared quasi-solid electrolyte can meet the usage requirements under high voltage, high current, and low temperature environments. The present invention also designs a precursor solution for preparing the quasi-solid electrolyte, a preparation method, and its application in batteries.

[0010] The technical solution of the present invention is realized as follows:

[0011] A precursor solution, comprising a carbonate solvent, a sulfate solvent, and a conductive lithium salt;

[0012] The addition amount of the sulfate solvent is 0.01 - 1 vol% of the carbonate solvent, and the two are used as the solvent system of the precursor solution;

[0013] The concentration of the conductive lithium salt in the solvent system is 0.5 mol / L - 5 mol / L;

[0014] It further comprises an added initiator or catalyst, and the addition amount of the initiator or catalyst in the solvent system is 0.1 mmol / L - 1 mol / L.

[0015] Preferably, the carbonate solvent includes but is not limited to one or more of vinylene carbonate (VC), ethylene vinylene carbonate (VEC), dimethyl carbonate (DMC), and propylene carbonate, mixed in any proportion.

[0016] More preferably, the carbonate solvent is only vinylene carbonate, or a mixture of vinylene carbonate and ethylene vinylene carbonate in any proportion.

[0017] Preferably, the sulfate solvent includes but is not limited to one or more of dimethyl sulfite (DMS), diethyl sulfite (DES), ethyl thioacetate (ETFA), methyl thioacetate (MTFA), and dimethyl sulfate (DMSO), mixed in any proportion.

[0018] More preferably, the sulfate solvent is dimethyl sulfite (DMS).

[0019] Preferably, the conductive lithium salt includes, but is not limited to, one or more of lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), lithium difluoro(dioxalato)phosphate (LiDFDOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP), which are mixed in any proportion.

[0020] Preferably, the conductive lithium salt is composed of at least two of the above-mentioned conductive lithium salts mixed in any proportion.

[0021] More preferably, the conductive lithium salt is composed of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and lithium difluoro(oxalato)borate (LiDFOB) mixed in any proportion.

[0022] Preferably, the initiator includes, but is not limited to, azobisisobutyronitrile (AIBN) or benzoyl peroxide (BPO), or a mixture of the two in any proportion.

[0023] For the preparation method of the above-mentioned precursor solution, first mix the conductive lithium salt with a carbonate solvent, then add a sulfate solvent and an initiator, and mix them together to form a liquid mixture to obtain the precursor solution.

[0024] A quasi-solid electrolyte is directly polymerized from the above-mentioned precursor solution.

[0025] The quasi-solid electrolyte prepared by the present invention has a high lithium ion transference number (>0.8) and a very wide electrochemical stability window (≥5.4V vs. Li + / Li). It has excellent cycling performance under the conditions of high voltage 4.5V and high rate 2C. It can not only work stably for a long time at room temperature, but even work normally in a low-temperature environment of -30°C. Specifically, the quasi-solid electrolyte prepared by the present invention can work normally in a wide temperature range of -30°C to 30°C, effectively solving the performance bottleneck of existing electrolytes under high voltage, low temperature and high current conditions. At the same time, it also meets the requirements of dynamically stable interface construction under high voltage, efficient ion conduction channels under low temperature, and rapid charge transfer under high current. It also has voltage tolerance, temperature adaptability and interface compatibility, providing a key new electrolyte material for the development of high-energy batteries, which is of great significance for improving the performance of lithium batteries and expanding their application range.

[0026] As can be seen from the above, the preparation methods of the precursor solution and quasi-solid-state electrolyte of the present invention are simple, easy for large-scale industrial production, have broad market application prospects and great commercial value, and are expected to provide strong support for the development of lithium-ion batteries with high energy density, long cycle life and wide temperature application range, promote technological progress and industrial upgrading in fields such as electric vehicles and energy storage systems, and meet the growing high-performance energy demand.

[0027] Preferably, the precursor solution is allowed to stand at 0 to 80 °C for 0 to 24 hours for polymerization and curing to form the quasi-solid-state electrolyte.

[0028] More preferably, the precursor solution is placed in an environment temperature of at least 60 °C and kept warm for at least 12 h to complete polymerization and curing to form the quasi-solid-state electrolyte.

[0029] More preferably, the precursor solution is allowed to stand at room temperature for at least 24 h to complete polymerization and curing to form the quasi-solid-state electrolyte.

[0030] The present invention also discloses the application of the above quasi-solid-state electrolyte in a battery.

[0031] The battery includes the above quasi-solid-state electrolyte, and the quasi-solid-state electrolyte is directly formed by in-situ polymerization of the above precursor solution inside the battery.

[0032] During the in-situ polymerization process, the carbonate component as a monomer polymerizes to form an artificial solid electrolyte interface (SEI) and an artificial cathode electrolyte interface (CEI), thereby achieving good interfacial contact between the polymer electrolyte and the electrode and effectively reducing the interfacial resistance. In addition, the inorganic compound layer formed by the organic solvent containing elements such as sulfur (S), fluorine (F), boron (B), and phosphorus (P) has excellent electron delocalization effect and reactivity, and can stabilize SEI and CEI respectively in different environments of the positive electrode and the negative electrode, realizing interface optimization and performance improvement. Moreover, the low-melting-point organic solvent can still remain liquid at low temperature, providing a fast migration channel for lithium ions, significantly increasing the conductivity, reducing the interfacial impedance, and promoting the transfer of ions at the interface.

[0033] Specifically, the battery is a quasi-solid-state lithium battery, and the assembly and laying materials follow the following order:

[0034] Positive electrode case → positive electrode → coating the precursor solution → separator → coating the precursor solution → negative electrode → gasket → shrapnel → negative electrode case. The precursor solution is directly polymerized in-situ inside the quasi-solid-state lithium battery by drying or standing to form a quasi-solid-state lithium battery with a quasi-solid-state electrolyte.

[0035] Specifically, the battery is a quasi-solid-state lithium battery, and the assembly and laying materials follow the following order:

[0036] Positive electrode case → positive electrode → placing the polymerized and solidified quasi-solid electrolyte → separator → placing the polymerized and solidified quasi-solid electrolyte → negative electrode → gasket → elastic sheet → negative electrode case, to fabricate a quasi-solid state lithium battery with a quasi-solid state electrolyte.

[0037] Preferably, the preparation method of the positive electrode is as follows:

[0038] (1) Grind and mix 60 - 98 wt% of positive electrode active material, 1 - 30 wt% of conductive additive, and 1 - 30 wt% of binder evenly, and the total of the three is 100%;

[0039] (2) Prepare the ground material in step (1) into a positive electrode slurry with a solid content of 15 - 70 wt%, evenly coat the positive electrode slurry on the surface of the metal foil, and then dry it in a vacuum oven at 60 - 100 °C for 12 - 24 h to obtain the positive electrode.

[0040] Specifically, the positive electrode active material that can be used for the positive electrode is divided into lithium battery positive electrode active material or sodium battery positive electrode active material.

[0041] Preferably, the lithium battery positive electrode active material includes but is not limited to lithium nickel cobalt manganese oxide (NCM), lithium iron phosphate (LFP), lithium cobalt oxide (LiCoO2), lithium nickel manganese oxide (LNMO), lithium nickel cobalt aluminum oxide (NCA), lithium-rich materials (LLOs), lithium manganese oxide (LiMn2O4), etc., and one or more of them are mixed in any proportion.

[0042] More preferably, the lithium battery positive electrode active material is lithium iron phosphate (LFP) or high-nickel ternary material (NCM90). When the quasi-solid state electrolyte is paired with these two materials, it shows more excellent electrochemical performance during cycling under high voltage and high rate conditions.

[0043] Preferably, the preparation method of the negative electrode is as follows:

[0044] (1) Grind and mix 60 - 90 wt% of negative electrode active material, 5 - 30 wt% of conductive agent Super P, and 5 - 30 wt% of polyvinylidene fluoride (PVDF) evenly, and the total of the three is 100%;

[0045] (2) Add N-methylpyrrolidone (NMP) to the ground material in step (1) to prepare a negative electrode slurry with a solid content of 15 - 70 wt%, evenly coat the negative electrode slurry on the surface of the metal foil, and then dry it in a vacuum oven at 60 - 100 °C for 12 - 24 h to obtain the negative electrode.

[0046] Specifically, the negative electrode active material that can be used for the negative electrode is divided into lithium battery negative electrode active material or sodium battery negative electrode active material.

[0047] Preferably, the lithium battery anode active material is one or more of metallic lithium, metallic lithium alloy, silicon or silicon-carbon composite material, lithium titanate, graphite, tin dioxide, and lithium metal nitride, mixed in any proportion. More preferably, the lithium battery anode active material is metallic lithium or metallic lithium alloy or a mixture of the two in any proportion. Brief Description of the Drawings

[0048] Figure 1 It is an optical photograph of the morphology of the quasi-solid electrolyte PVC-01 before polymerization according to the present invention;

[0049] Figure 2 It is an optical photograph of the morphology of the quasi-solid electrolyte PVC-01 after polymerization according to the present invention;

[0050] Figure 3 It is the cycle curve of the NCM90||PVC-01||Li battery made of the quasi-solid electrolyte of Example 1;

[0051] Figure 4 It is the cycle curve of the NCM90||PVC-02||Li battery made of the quasi-solid electrolyte of Example 2;

[0052] Figure 5 It is the cycle curve of the NCM90||PVC-03||Li battery made of the quasi-solid electrolyte of Example 3;

[0053] Figure 6 It is the cycle curve of the NCM90||PVC-04||Li battery made of the quasi-solid electrolyte of Example 4;

[0054] Figure 7 It is the cycle curve of the NCM90||PVC-05||Li battery made of the quasi-solid electrolyte of Example 5;

[0055] Figure 8 It is the cycle curve of the NCM90||PVC-06||Li battery made of the quasi-solid electrolyte of Example 6;

[0056] Figure 9 It is the cycle curve of the NCM90||PVC-07||Li battery made of the quasi-solid electrolyte of Example 7;

[0057] Figure 10 It is the cycle curve of the NCM90||LIB-005||Li battery made of the quasi-solid electrolyte of Comparative Example 1;

[0058] Figure 11 It is the cycle curve of the NCM90||LIB-200||Li battery made of the quasi-solid electrolyte of Comparative Example 2;

[0059] Figure 12 The graph for measuring the lithium ion transference number of the quasi-solid state electrolyte PVC-01 in Example 1;

[0060] Figure 13 The linear sweep voltammogram of the quasi-solid state electrolyte PVC-01 in Example 1;

[0061] Figure 14 The charge-discharge cycle performance graph of the Li||PVC-01||Li battery made of the quasi-solid state electrolyte PVC-01 in Example 1;

[0062] Figure 15 The 1C cycle curve at 30 °C of the LFP||PVC-01||Li battery made of the quasi-solid state electrolyte PVC-01 in Example 1;

[0063] Figure 16 The 0.5C cycle curve at -10 °C of the LFP||PVC-01||Li battery made of the quasi-solid state electrolyte PVC-01 in Example 1;

[0064] Figure 17 The rate graph at 30 °C and voltage range of 2.8V - 4.5V of the NCM90||PVC-01||Li battery made of the quasi-solid state electrolyte PVC-01 in Example 1;

[0065] Figure 18 The 2C cycle curve at 30 °C and voltage range of 2.8V - 4.5V of the NCM90||PVC-01||Li battery made of the quasi-solid state electrolyte PVC-01 in Example 1;

[0066] Figure 19 The 0.1C cycle curve at wide temperature range (-30 °C to 30 °C) and voltage range of 2.8V - 4.5V of the NCM90||PVC-01||Li battery made of the quasi-solid state electrolyte PVC-01 in Example 1;

[0067] Figure 20 The test result graph of stable cycle at 0.1C - 2C at wide temperature range (-10 °C to 30 °C), voltage range of 2.8V - 4.5V of the NCM90||PVC-01||Li battery made of the quasi-solid state electrolyte PVC-01 in Example 1;

[0068] Figure 21 The 0.5C cycle curve at -10 °C and voltage range of 2.8V - 4.5V of the NCM90||PVC-01||Li battery made of the quasi-solid state electrolyte PVC-01 in Example 1. Detailed implementation manners

[0069] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0070] Example 1

[0071] A precursor solution, including the following preparation steps:

[0072] (1) Place 1 ml of VC solvent in a glass bottle, and then add 0.17 g of LiDFOB and 0.11 g of LiTFSI, and dissolve all the lithium salts with a magnetic stirrer.

[0073] (2) Then add 0.1 ml of DMS solvent and 30 mg of AIBN, and continue to stir for a period of time to fully mix the components to obtain a precursor solution; take a part of the precursor solution for the following morphological change test.

[0074] A quasi-solid-state electrolyte is made in the following way:

[0075] Place the above-mentioned part of the precursor solution in an oven at 60 °C and keep it warm for 12 h to obtain the quasi-solid-state electrolyte PVC-01.

[0076] A quasi-solid-state lithium battery is assembled and laid out in the following order:

[0077] Positive electrode case → positive electrode → coat 30 μL of precursor solution → separator → coat 30 μL of precursor solution → negative electrode → gasket → shrapnel → negative electrode case; put it into an oven at 60 °C and dry for 12 h. The precursor solution directly polymerizes in situ inside the quasi-solid-state lithium battery to make a quasi-solid-state lithium battery with a quasi-solid-state electrolyte.

[0078] The preparation method of the positive electrode is as follows:

[0079] (1) Grind and mix the positive electrode active material, conductive additive, and binder evenly at 90%:5%:5%.

[0080] (2) Mix the ground material in step (1) with N-methylpyrrolidone (NMP) to prepare a positive electrode slurry with a solid content of 45%. Coat the positive electrode slurry evenly on the surface of the metal foil, and then dry it in a vacuum oven at 80 °C for 18 h to obtain the positive electrode.

[0081] The preparation method of the negative electrode is as follows:

[0082] (1) Grind and mix the negative electrode active material, conductive additive, and binder evenly at a ratio of 90%:5%:5% (the negative electrode can also be a lithium metal sheet directly);

[0083] (2) Mix the ground material from step (1) with N-methylpyrrolidone (NMP) to prepare a negative electrode slurry with a solid content of 45%. Coat the negative electrode slurry evenly on the surface of the metal foil, and then dry it in a vacuum oven at 80 °C for 18 h to obtain the negative electrode.

[0084] A quasi-solid-state lithium battery, with the positive electrode active material being LFP, and the remaining preparation steps being the same as those of the above battery.

[0085] The above preparation processes are all completed in a glove box filled with argon.

[0086] Example 2

[0087] A precursor solution, including the following preparation steps:

[0088] (1) Place 0.5 ml of VC and 0.5 ml of VEC in a glass bottle, then add 0.17 g of LiDFOB and 0.11 g of LiTFSI, and dissolve all the lithium salts with a magnetic stirrer;

[0089] (2) Then add 0.1 ml of DMS solvent and 30 mg of AIBN, and continue to stir for a period of time to fully mix all components to obtain a precursor solution; Take a part of the precursor solution for the following morphological change test.

[0090] A quasi-solid-state electrolyte is made by the following method:

[0091] Place the above precursor solution in an oven at 60 °C and keep it warm for 12 h to obtain the quasi-solid-state electrolyte PVC-02.

[0092] A quasi-solid-state lithium battery is assembled and laid out in the following order:

[0093] Positive electrode case → Positive electrode → Coat 30 μL of precursor solution → Separator → Coat 30 μL of precursor solution → Negative electrode → Spacer → Spring piece → Negative electrode case; Put it in an oven at 60 °C and dry it for 12 h. The precursor solution directly polymerizes in situ inside the quasi-solid-state lithium battery to make a quasi-solid-state lithium battery with a quasi-solid-state electrolyte.

[0094] The preparation method of the positive electrode is as follows:

[0095] (1) Grind and mix the positive electrode active material, conductive additive, and binder evenly at a ratio of 90%:5%:5%;

[0096] (2) Mix the ground material from step (1) with N-methylpyrrolidone (NMP) to prepare a positive electrode slurry with a solid content of 45%. Coat the positive electrode slurry evenly on the surface of the metal foil, and then dry it in a vacuum oven at 80 °C for 18 h to obtain the positive electrode.

[0097] The preparation method of the negative electrode is as follows:

[0098] (1) Grind and mix the negative electrode active material, conductive additive, and binder evenly at a ratio of 90%:5%:5% (the negative electrode can also be directly a lithium metal sheet);

[0099] (2) Mix the ground material from step (1) with N-methylpyrrolidone (NMP) to prepare a negative electrode slurry with a solid content of 45%. Coat the negative electrode slurry evenly on the surface of the metal foil, and then dry it in a vacuum oven at 80 °C for 18 h to obtain the negative electrode.

[0100] The above preparation processes are all completed in a glove box filled with argon.

[0101] Example 3

[0102] A precursor solution, including the following preparation steps:

[0103] (1) Place 1 ml of VEC solvent in a glass bottle, then add 0.17 g of LiDFOB and 0.11 g of LiTFSI, and dissolve all the lithium salts with a stir bar;

[0104] (2) Then add 0.1 ml of DMS solvent and 30 mg of AIBN, and continue to stir for a period of time to fully mix all components to obtain a precursor solution; Take a part of the precursor solution for the following morphological change test.

[0105] A quasi-solid-state electrolyte is made in the following way:

[0106] Place the above precursor solution in an oven at 80 °C and keep it warm for 12 h to obtain the quasi-solid-state electrolyte PVC-03.

[0107] A quasi-solid-state lithium battery is assembled and laid out in the following order:

[0108] Positive electrode case → Positive electrode → Coat 30 μL of precursor solution → Separator → Coat 30 μL of precursor solution → Negative electrode → Spacer → Spring piece → Negative electrode case; Put it in an oven at 60 °C and dry it for 12 h. The precursor solution directly polymerizes in situ inside the quasi-solid-state lithium battery to make a quasi-solid-state lithium battery with a quasi-solid-state electrolyte.

[0109] The preparation method of the positive electrode is as follows:

[0110] (1) Grind and mix the positive electrode active material, conductive additive, and binder evenly at a ratio of 90%:5%:5%.

[0111] (2) Mix the ground material from step (1) with N-methylpyrrolidone (NMP) to prepare a positive electrode slurry with a solid content of 45%. Coat the positive electrode slurry evenly on the surface of the metal foil, and then dry it in a vacuum oven at 80 °C for 18 h to obtain the positive electrode.

[0112] The preparation method of the negative electrode is as follows:

[0113] (1) Grind and mix the negative electrode active material, conductive additive, and binder evenly at a ratio of 90%:5%:5% (the negative electrode can also be a metal lithium sheet directly);

[0114] (2) Mix the ground material from step (1) with N-methylpyrrolidone (NMP) to prepare a negative electrode slurry with a solid content of 45%. Coat the negative electrode slurry evenly on the surface of the metal foil, and then dry it in a vacuum oven at 80 °C for 18 h to obtain the negative electrode.

[0115] The above preparation processes are all completed in a glove box filled with argon.

[0116] Example 4

[0117] A precursor solution, including the following preparation steps:

[0118] (1) Place 1 ml of VC solvent in a glass bottle, then add 0.3 g of LiDFOB, and dissolve all the lithium salts with a stir bar;

[0119] (2) Then add 0.1 ml of DMS solvent and 30 mg of AIBN, and continue to stir for a period of time to fully mix all components to obtain a precursor solution; Take a part of the precursor solution for the following morphological change test.

[0120] A quasi-solid-state electrolyte is made by the following method:

[0121] Place the above precursor solution in an oven at 80 °C and keep it warm for 12 h to obtain the quasi-solid-state electrolyte PVC-04.

[0122] A quasi-solid-state lithium battery is assembled and laid out in the following order:

[0123] Positive electrode case → Positive electrode → Coat 30 μL of precursor solution → Separator → Coat 30 μL of precursor solution → Negative electrode → Spacer → Spring piece → Negative electrode case; Put it in an oven at 60 °C and dry it for 12 h. The precursor solution directly polymerizes in situ inside the quasi-solid-state lithium battery to make a quasi-solid-state lithium battery with a quasi-solid-state electrolyte.

[0124] The preparation method of the positive electrode is as follows:

[0125] (1) Grind and mix the positive electrode active material, conductive additive, and binder evenly at a ratio of 90%:5%:5%.

[0126] (2) Mix the ground material from step (1) with N-methylpyrrolidone (NMP) to prepare a positive electrode slurry with a solid content of 45%. Coat the positive electrode slurry evenly on the surface of the metal foil, and then dry it in a vacuum oven at 80 °C for 18 h to obtain the positive electrode.

[0127] The preparation method of the negative electrode is as follows:

[0128] (1) Grind and mix the negative electrode active material, conductive additive, and binder evenly at a ratio of 90%:5%:5% (the negative electrode can also be directly a lithium metal sheet).

[0129] (2) Mix the ground material from step (1) with N-methylpyrrolidone (NMP) to prepare a negative electrode slurry with a solid content of 45%. Coat the negative electrode slurry evenly on the surface of the metal foil, and then dry it in a vacuum oven at 80 °C for 18 h to obtain the negative electrode.

[0130] The above preparation processes are all completed in a glove box filled with argon.

[0131] Example 5

[0132] A precursor solution includes the following preparation steps:

[0133] (1) Place 1 ml of VC solvent in a glass bottle, then add 0.45 g of LiTFSI, and dissolve all the lithium salts with a stir bar.

[0134] (2) Then add 0.1 ml of DMS solvent and 30 mg of AIBN, and continue to stir for a period of time to fully mix all components to obtain a precursor solution; take a part of the precursor solution for the following morphological change test.

[0135] A quasi-solid-state electrolyte is made by the following method:

[0136] Place the above precursor solution in an oven at 80 °C and keep it warm for 12 h to obtain the quasi-solid-state electrolyte PVC-05.

[0137] The above preparation processes are all completed in a glove box filled with argon.

[0138] A quasi-solid-state lithium battery is assembled and laid out in the following order:

[0139] Positive electrode case → Positive electrode → Coating 30 μL of precursor solution → Separator → Coating 30 μL of precursor solution → Negative electrode → Spacer → Spring piece → Negative electrode case; Place it in an oven at 60 °C and dry for 12 h. The precursor solution polymerizes in situ directly inside the quasi-solid-state lithium battery to produce a quasi-solid-state lithium battery with a quasi-solid-state electrolyte.

[0140] The preparation method of the positive electrode is as follows:

[0141] (1) Grind and mix the positive electrode active material, conductive additive, and binder evenly at 90%:5%:5%;

[0142] (2) Mix the ground material in step (1) with N-methylpyrrolidone (NMP) to prepare a positive electrode slurry with a solid content of 45%. Coat the positive electrode slurry evenly on the surface of the metal foil, and then dry it in a vacuum oven at 80 °C for 18 h to obtain the positive electrode.

[0143] The preparation method of the negative electrode is as follows:

[0144] (1) Grind and mix the negative electrode active material, conductive additive, and binder evenly at 90%:5%:5% (the negative electrode can also be directly a lithium metal sheet);

[0145] (2) Mix the ground material in step (1) with N-methylpyrrolidone (NMP) to prepare a negative electrode slurry with a solid content of 45%. Coat the negative electrode slurry evenly on the surface of the metal foil, and then dry it in a vacuum oven at 80 °C for 18 h to obtain the negative electrode.

[0146] Example 6

[0147] A precursor solution, including the following preparation steps:

[0148] (1) Place 1 ml of VC solvent in a glass bottle, and then add 0.17 g of LiDFOB and 0.11 g of LiTFSI. Use a magnetic stirrer to dissolve all the lithium salts;

[0149] (2) Then add 0.2 ml of DMS solvent and 30 mg of AIBN, and continue to stir for a period of time to fully mix all components to obtain the precursor solution; Take a part of the precursor solution for the following morphological change test.

[0150] A quasi-solid-state electrolyte is made by the following method:

[0151] Place the above precursor solution in an oven at 60 °C and keep it warm for 12 h to obtain the quasi-solid-state electrolyte PVC-06.

[0152] A quasi-solid-state lithium battery is assembled and laid out in the following order:

[0153] Positive electrode case → positive electrode → coating 30 μL of precursor solution → separator → coating 30 μL of precursor solution → negative electrode → gasket → shrapnel → negative electrode case; Place it in an oven at 60 °C and dry for 12 h. The precursor solution directly polymerizes in situ inside the quasi-solid-state lithium battery to form a quasi-solid-state lithium battery with a quasi-solid-state electrolyte.

[0154] The preparation method of the positive electrode is as follows:

[0155] (1) Grind and mix the positive electrode active material, conductive additive, and binder evenly at a ratio of 90%:5%:5%;

[0156] (2) Mix the ground material in step (1) with N-methylpyrrolidone (NMP) to prepare a positive electrode slurry with a solid content of 45%. Coat the positive electrode slurry evenly on the surface of the metal foil, and then dry it in a vacuum oven at 80 °C for 18 h to obtain the positive electrode.

[0157] The preparation method of the negative electrode is as follows:

[0158] (1) Grind and mix the negative electrode active material, conductive additive, and binder evenly at a ratio of 90%:5%:5% (the negative electrode can also be directly a lithium metal sheet);

[0159] (2) Mix the ground material in step (1) with N-methylpyrrolidone (NMP) to prepare a negative electrode slurry with a solid content of 45%. Coat the negative electrode slurry evenly on the surface of the metal foil, and then dry it in a vacuum oven at 80 °C for 18 h to obtain the negative electrode.

[0160] The above preparation process is all completed in a glove box filled with argon.

[0161] Example 7

[0162] A precursor solution, including the following preparation steps:

[0163] (1) Place 1 ml of VC solvent in a glass bottle, then add 0.17 g of LiDFOB and 0.11 g of LiTFSI, and dissolve all the lithium salts with a stir bar;

[0164] (2) Then add 0.1 ml of DES solvent and 30 mg of AIBN, and continue to stir for a period of time to fully mix the components to obtain the precursor solution; Take a part of the precursor solution for the following morphological change test.

[0165] A quasi-solid-state electrolyte is made by the following method:

[0166] Place the above precursor solution in an oven at 60 °C and keep it warm for 12 h to obtain the quasi-solid-state electrolyte PVC-07.

[0167] A quasi-solid-state lithium battery is assembled and paved in the following order:

[0168] Positive electrode case → positive electrode → coating 30 μL of precursor solution → separator → coating 30 μL of precursor solution → negative electrode → gasket → shrapnel → negative electrode case; put it into an oven and dry at 60 °C for 12 h. The precursor solution directly polymerizes in situ inside the quasi-solid-state lithium battery to make a quasi-solid-state lithium battery with a quasi-solid-state electrolyte.

[0169] The preparation method of the positive electrode is as follows:

[0170] (1) Grind and mix the positive electrode active material, conductive additive and binder evenly at 90%:5%:5%;

[0171] (2) Mix the ground material in step (1) with N-methylpyrrolidone (NMP) to prepare a positive electrode slurry with a solid content of 45%. Coat the positive electrode slurry evenly on the surface of the metal foil, and then dry it in a vacuum oven at 80 °C for 18 h to obtain the positive electrode.

[0172] The preparation method of the negative electrode is as follows:

[0173] (1) Grind and mix the negative electrode active material, conductive additive and binder evenly at 90%:5%:5% (the negative electrode can also be directly a lithium metal sheet);

[0174] (2) Mix the ground material in step (1) with N-methylpyrrolidone (NMP) to prepare a negative electrode slurry with a solid content of 45%. Coat the negative electrode slurry evenly on the surface of the metal foil, and then dry it in a vacuum oven at 80 °C for 18 h to obtain the negative electrode.

[0175] The above preparation processes are all completed in a glove box filled with argon.

[0176] Comparative Example 1

[0177] Self-made electrolyte LIB005: 1 M LiPF6 in EC:EMC = 3:7 Vol%.

[0178] The battery assembly process follows positive electrode case → positive electrode → coating 30 μL of electrolyte → separator → coating 30 μL of electrolyte → negative electrode → gasket → shrapnel → negative electrode case; the preparation methods of the positive and negative electrodes are the same as those in Example 1.

[0179] The above preparation processes are all completed in a glove box filled with argon.

[0180] Comparative Example 2

[0181] Self-made electrolyte LIB200: 1 M LiPF6 in DEC:EC = 2:1 Vol% with 10% FEC.

[0182] The battery assembly process follows the sequence: positive electrode case → positive electrode → coating 30 μL of electrolyte → separator → coating 30 μL of electrolyte → negative electrode → gasket → shrapnel → negative electrode case; the preparation methods of the positive and negative electrodes are the same as those in Example 1.

[0183] The above preparation processes are all completed in a glove box filled with argon.

[0184] Performance Testing

[0185] 1. Morphological change test of quasi-solid electrolyte

[0186] As Figure 1 shown, the precursor solution prepared in Example 1 was placed in a glass bottle and inverted. The precursor solution flowed and aggregated to the position of the bottle cap, indicating that the precursor solution was a flowable liquid before polymerization.

[0187] As Figure 2 shown, the precursor solution in the glass bottle was allowed to stand for 24 h and then inverted. The precursor solution had polymerized and solidified at the bottom of the bottle and could not flow, indicating that the precursor solution could polymerize and solidify into a solid with a certain strength and could not flow.

[0188] The precursor solutions prepared in Examples 2 to 7 were all tested according to the above method, and the results showed that they were all flowable liquids before polymerization and polymerized and solidified into solids with a certain strength and could not flow after standing for at least 24 h.

[0189] 2. Battery cycle test

[0190] In an Ar glove box, the quasi-solid electrolytes PVC-01 to PVC-07 prepared in Examples 1 to 7 were further made into test batteries with the structure of "NCM90||quasi-solid electrolyte||Li".

[0191] In an Ar glove box, the electrolyte prepared in Comparative Example 1 was made into a test battery with the structure of "NCM90||LIB-005||Li".

[0192] In an Ar glove box, the electrolyte prepared in Comparative Example 2 was made into a test battery with the structure of "NCM90||LIB-200||Li".

[0193] Test conditions: at 30 °C, voltage range 2.8 - 4.5 V, cycling 100 times at 1C.

[0194] The results are as Figures 3 to 12 shown, and the capacity retention rates of each test battery are as follows in the table.

[0195] Test battery Capacity retention rate NCM90||PVC-01||Li 92％ NCM90||PVC-02||Li 90.03％ NCM90||PVC-03||Li 86.5％ NCM90||PVC-04||Li 88.01％ NCM90||PVC-05||Li 84.8％ NCM90||PVC-06||Li 91.04％ NCM90||PVC-07||Li 82.92％ NCM90||LIB-005||Li 72.7％ NCM90||LIB-200||Li 80.28％

[0196] 3. Lithium ion transference number test

[0197] In an Ar glove box, the "quasi-solid electrolyte PVC-01" prepared in Example 1 was placed between lithium sheets for battery assembly, and then the lithium ion transference number of this battery was tested by an electrochemical workstation.

[0198] The results are as Figure 12 shown. The lithium ion transference number of the "quasi-solid electrolyte PVC-01" prepared in Example 1 was 0.87, indicating that the lithium ion battery containing the "quasi-solid electrolyte" of the present invention has excellent fast charging ability.

[0199] 4. Redox potential test

[0200] In an Ar glove box, the "quasi-solid electrolyte PVC-01" prepared in Example 1 was placed between a stainless steel sheet and a lithium sheet for battery assembly, and then a linear sweep voltammetry test was carried out on this battery by an electrochemical workstation. The test potential range was from 0 V to 6.55 V, and the scan rate was 1 mV / s.

[0201] The results are as Figure 13 shown. The redox potential of Example 1 was as high as 5.6 V, indicating that the quasi-solid electrolyte prepared by the present invention has a wide electrochemical window.

[0202] 5. Lithium symmetric battery cycling test

[0203] In an Ar glove box, the "quasi-solid electrolyte PVC-01" prepared in Example 1 was used to fabricate a lithium symmetric battery with the structure of "Li||PVC-01||Li".

[0204] The cycling performance test was carried out in a BlueTEC (Land) test system at a current density of 0.2 mA / cm 2 (areal capacity 0.1 mAh / cm 2 , temperature -10 °C), and the charge-discharge process was alternated every half hour during the test process.

[0205] The results are as Figure 14 shown. The lithium symmetric battery assembled with the quasi-solid electrolyte prepared in Example 1 could stably cycle for 1800 h at -10 °C and 0.2 mA / cm 2 , showing good cycling performance.

[0206] 6. Cycling performance test of LFP||PVC-01||Li battery

[0207] In an Ar glove box, the "quasi-solid electrolyte PVC-01" prepared in Example 1 was used to fabricate a test battery with the structure of "LFP||PVC-01||Li".

[0208] (6.1) Test conditions: at 30 °C, voltage range 2.8 - 4 V, cycling at 1C.

[0209] The results are as Figure 15 shown. When the LFP||PVC-01||Li test battery is cycled to 550 cycles, its capacity retention rate is 96.3%.

[0210] (6.2) Test conditions: at -10 °C, 2.8 - 4 V, cycling at 0.5C.

[0211] The results are as Figure 16 shown. When the LFP||PVC-01||Li test battery is cycled to 500 cycles, its capacity retention rate is 88.2%; when cycled to 1000 cycles, its capacity retention rate is 71.9%.

[0212] 7. NCM90||PVC-01||Li battery performance test

[0213] In an Ar glove box, the "quasi-solid electrolyte PVC-01" prepared in Example 1 was made into a test battery with the structure of "NCM90||PVC-01||Li".

[0214] (7.1) Charge-discharge performance test: at 30 °C, voltage range 2.8 V - 4.5 V.

[0215] The charge-discharge curves are as Figure 17 shown. At 0.1C, 0.2C, 0.5C, 1C, and 2C rates, the test battery can provide capacities of 241 mAh·g-1, 234.5 mAh·g-1, 220.3 mAh·g-1, 209.7 mAh·g-1, and 198 mAh·g-1, indicating that the present invention can achieve fast charge cycling without additional power loss.

[0216] (7.2) Test conditions: at 30 °C, voltage range 2.8 - 4.5 V, cycling at 2C for 100 cycles.

[0217] The results are as Figure 18 shown. When the NCM90||PVC-01||Li test battery is cycled to 100 cycles, its capacity retention rate is 89%.

[0218] (7.3) Test conditions: wide temperature range from -30 °C to 30 °C (specifically -30 °C, -20 °C, -10 °C, 0 °C, and 30 °C), voltage range 2.8 - 4.5 V, stable cycling test at 0.1C.

[0219] The results are as Figure 19 shown. The NCM90||PVC-01||Li test battery can still operate stably under the harsh conditions of -30 °C low temperature and 4.5 V high voltage.

[0220] (7.4) Test conditions: wide temperature range from -10°C to 30°C (specifically -10°C, 0°C, and 30°C), voltage range 2.8 - 4.5V, cyclic stability test with cycling at 0.1 - 2C.

[0221] The results are as Figure 20 shown. The NCM90||PVC - 01||Li test battery can still operate stably under the harsh conditions of low temperature at -10°C, high rate of 2C, and high voltage of 4.5V.

[0222] (7.5) Test conditions: at -10°C, voltage range 2.8 - 4.5V, cycling 110 laps at 0.5C.

[0223] The results are as Figure 21 shown. The NCM90||PVC - 01||Li test battery has no capacity loss.

[0224] From the above test results, it can be seen that: the quasi - solid electrolyte prepared by the present invention in combination with high - nickel NCM90 can work stably under harsh conditions such as high rate of 2C and high voltage of 4.5V.

[0225] According to the disclosure and teaching of the above specification, those skilled in the art of the present invention can also make changes and modifications to the above - mentioned embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A precursor solution, characterized in that Contains a sulfate solvent, a conductive lithium salt and a carbonate solvent as a polymerization monomer; The addition amount of the sulfate solvent is 0.01 to 1 vol% of the carbonate solvent, and the two serve as the solvent system of the precursor solution; The concentration of the conductive lithium salt in the solvent system is 0.5 mol / L to 5 mol / L; The method further comprises adding an initiator or a catalyst, wherein the amount of the initiator or the catalyst added to the solvent system is 0.1 mmol / L to 1 mol / L.

2. The precursor solution according to claim 1, characterized in that The carbonate solvent is one or more of vinylene carbonate, ethylene carbonate, dimethyl carbonate, and propylene carbonate mixed in any proportion; The sulfate ester solvent is one of dimethyl sulfite, diethyl sulfite, ethyl thioacetate, methyl thioacetate, and dimethyl sulfate, or a mixture of more than one of them in any proportion.

3. The precursor solution according to claim 2, characterized in that The carbonate solvent is only vinylene carbonate, or vinylene carbonate and ethylene carbonate are mixed in any proportion; The sulfate ester solvent is dimethyl sulfite.

4. The precursor solution according to any one of claims 1 to 3, characterized in that: The conductive lithium salt is one or more of lithium hexafluorophosphate, lithium bis(trifluoromethylsulfonyl imide), lithium bis(fluorosulfonyl imide), lithium tetrafluoroborate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate in any proportion; The initiator is azobisbutyronitrile or dibenzoyl peroxide or a mixture of the two in any proportion.

5. The precursor solution according to claim 4, characterized in that The conductive lithium salt is prepared by mixing lithium bis(trifluoromethylsulfonyl)imide and lithium fluorooxalate borate in any proportion.

6. The method for preparing a precursor solution according to any one of claims 1 to 5, characterized in that: The conductive lithium salt is first mixed with a carbonate solvent, and then a sulfate solvent and an initiator are added and mixed together to form a liquid mixture to prepare a precursor solution.

7. A quasi-solid electrolyte, characterized in that: It is prepared by direct polymerization of the precursor solution described in any one of claims 1 to 5.

8. The quasi-solid electrolyte according to claim 7, characterized in that The mixture is allowed to stand at 0 to 80°C for 0 to 24 hours for polymerization and curing.

9. Use of the quasi-solid electrolyte according to claim 7 or 8 in a battery.

10. Use of the quasi-solid electrolyte in a battery according to claim 9, characterized in that: The battery comprises a quasi-solid electrolyte, and the quasi-solid electrolyte is prepared by directly in-situ polymerization of the precursor solution according to any one of claims 1 to 5 inside the battery.

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